第一篇：機(jī)械工程專業(yè)英語(yǔ)第二版必考翻譯(完整版)

1.With low-power machinery or vehicles the operator can usually apply sufficient force through a simple mechanical linkage from the pedle or handle to the stationary part of the brake.In many cases, however, this force must be multiplied by using an elaborate braking system.（P5）用低能機(jī)器或傳力工具，操作者通過(guò)向踏板或把手的一個(gè)簡(jiǎn)單機(jī)械連接構(gòu)件作用足夠的力量到車(chē)閘固定的部分。大多數(shù)情況，然而，用一個(gè)詳細(xì)（復(fù)雜）的車(chē)閘系統(tǒng)使這個(gè)力量成倍增加。

2.The fundamental principle involved is the use of compressed air acting through a piston in a cylinder to set block brakes on the wheels.The action is simultaneous on the wheels of all the cars in the train.The compressed air is carried through a strong hose from car to car with couplings between cars;its release to all the separate block brake units, at the same time, is controlled by the engineer.(Braking Systems)（P5）

相關(guān)的基本原理是使用壓縮氣體，通過(guò)氣缸內(nèi)的活塞將閘塊壓在車(chē)輪起作用。列車(chē)的所有車(chē)廂上的車(chē)輪同時(shí)動(dòng)作。壓縮氣體通過(guò)一個(gè)堅(jiān)固的管道在由聯(lián)軸器連接的車(chē)廂之間傳輸；工程師控制其在同一時(shí)間釋放到所有獨(dú)立的閘塊單元。

3.When the brake pedal of an automobile is depressed, a force is applied to a piston in a

master cylinder.The piston forces hydraulic fluid through metal tubing into a cylinder in each wheel where the fluid’s pressure moves two pistons that press the brake shoes against the drum.(Braking Systems)（P5）

當(dāng)踩下汽車(chē)剎車(chē)的踏板，在主汽缸中的活塞上施加一個(gè)力。活塞驅(qū)動(dòng)液壓流體通過(guò)金屬管道進(jìn)入每個(gè)車(chē)輪氣缸，在那里液壓移動(dòng)兩個(gè)活塞將閘片壓向輪圈。

4.Machinery ontology including mechanical rack, mechanical connections and mechanical transmission, which is the basis of mechanical-electrical integration, plays a role in supporting the other functional units of the system and transmitting motion and power.Compared to purely mechanical products, the performance and functionality of integration technology in electrical and mechanical systems have been improved a lot, which requires mechanical ontology to adapt its new status in mechanical structure, materials, processing technology, as well as the areas of geometry.Accordingly, the new ontology is with high efficient, multi-functional, reliable and energy-saving, small, light-weighted and aesthetically pleasing characteristics.(Mechatronics System)（P7）

機(jī)械體包括機(jī)架、機(jī)械聯(lián)接和機(jī)械傳動(dòng)，它是機(jī)電一體化的基礎(chǔ)，作用是支撐系統(tǒng)其他功能單元，傳遞運(yùn)動(dòng)和動(dòng)力。和純機(jī)械產(chǎn)品相比，一體化技術(shù)的性能和功能在機(jī)電系統(tǒng)中大幅提高，它要求機(jī)械本體適應(yīng)在機(jī)械結(jié)構(gòu)、材料、加工技術(shù)以及這些領(lǐng)域中的幾何學(xué)下的新環(huán)境。相應(yīng)的，新的一體化具有高效、多功能、可靠、節(jié)能、小輕和美學(xué)的令人賞心悅目的特征。

5.Detecting sensor detecting sensor part includes a variety of sensors and signal detection circuit, and its function is to detect the process of mechatronic systems in the work itself and the changes of relevant parameters in external environment and transmit the information to the electronic control unit.Electronic control unit check the information and sends the corresponding control issues to the actuator.(Mechatronics System)（P7）

檢測(cè)傳感器部分包括各類傳感器、信號(hào)檢測(cè)電路，它的功能是檢測(cè)機(jī)電系統(tǒng)自身工作的工程，在外部環(huán)境下的相關(guān)參數(shù)的改變，將其信息傳給電子控制單元。電子控制單元通過(guò)檢查信息，送出相應(yīng)的指令到執(zhí)行機(jī)構(gòu)。

6.Electronic control unit, also known as ECU, is the core of mechatronic systems, responsible for the external commands and the signals output by sensors.It centralizes stores, computes and analyzes the information.Based on the results of information processing,instruction are issued according to a certain extent and pace to control the destination for the entire system.(Mechatronics System)（P7）

電子控制單元，也被稱為控制單元（ECU）控制，是機(jī)電系統(tǒng)的核心，負(fù)責(zé)外部命令和傳感器的信號(hào)輸出。它集中、存儲(chǔ)、計(jì)算并分析信息?；谛畔⑻幚淼慕Y(jié)果，按照一定的范圍和步調(diào)發(fā)出命令來(lái)實(shí)現(xiàn)控制整個(gè)系統(tǒng)的目標(biāo)。

7.It is put into a fairly standard machine tool that has had position sensing and motors on the control knobs installed.This is basically just a robot machinist.You use a rotating cutting tool to cut away all the metal that isn’t your crank.3D metal etch-a-sketch, with the computer interpolating, so the circles come out to be pretty smooth.(CNC Machining)（P9）

將數(shù)控系統(tǒng)裝入一個(gè)非常標(biāo)準(zhǔn)的機(jī)床，它在控制手柄上有位置感應(yīng)和馬達(dá)。這基本上是一個(gè)機(jī)械師。你能使用一個(gè)旋轉(zhuǎn)切削刀具切掉不是你設(shè)計(jì)的所有金屬。具有計(jì)算內(nèi)插的三維金屬蝕刻成型可以使得圓被加工得更光滑。

8.They(CNC machine)are complicated machines, full of servomechanisms, and measuring technology that can measure to 0.005mm(0.0001”)while covered in oil.A CNC machine has a minimum of 6 motors(including some to change tools, and one or more to pump oil and coolant various places).This translates to running costs that may be well over $1/minute.(The computer is not a significant part of the cost any more.)(CNC Machining)（P10）

數(shù)控機(jī)床是復(fù)雜的機(jī)器，具有伺服機(jī)構(gòu)和檢測(cè)技術(shù)，它能在覆蓋油膜狀態(tài)下檢測(cè)到0.005mm。數(shù)控機(jī)床至少有 6個(gè)馬達(dá)（包括一些用來(lái)?yè)Q刀具，一個(gè)或多個(gè)用來(lái)泵油和冷卻液的各地方）。這些化成運(yùn)行成本可能大大超過(guò)1美元/分鐘。（電腦不再是成本的一個(gè)重要部分.）

9.The smaller, denser chips can also provide speed benefits, because in high-speed devices, the length of time it takes a signal to travel a given distance can become a factor.(Integrated Circuit(IC))（P57）

小而密的芯片能提供速度優(yōu)勢(shì)，因?yàn)楦咚傺b置中，信號(hào)傳輸給定距離所需時(shí)間長(zhǎng)度是一個(gè)因素。

10．ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip.This increased capacity per unit area can be used to decrease cost and/or increase functionality-see Moore’s law which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years。（P58）

多年來(lái)集成電路持續(xù)向更小的外觀尺寸發(fā)展，允許每個(gè)芯片封裝更多的電路，這增加了單位面積的容量，可以被用于降低成本和/或增加功能。由Moore法則，用現(xiàn)代的解釋來(lái)說(shuō)，集成電路中晶體管的數(shù)量每?jī)赡隄q一倍。

11.In general, as the feature size shrinks, almost everything improves the cost per unit and the switching power consumption goes down, and the speed goes up.However, ICs with nanometer-scale devices are not without their problems, principal among which is leakage current, although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of high-k dielectrics.(Integrated Circuit(IC))（P58）一般隨著外觀尺寸的減小，幾乎任何物品的單位成本會(huì)改善（降低），轉(zhuǎn)換能源消耗會(huì)降低，速度提高。然而，納米級(jí)設(shè)備所用的 IC 芯片不是沒(méi)有問(wèn)題，其中最基本的是漏電流，盡管這些問(wèn)題不是不可克服的，它可被解決，或至少可通過(guò)引入高k值絕緣體被改善。

12.The major fabricating steps for integrated circuits include film formation, impurity doping, photolithography, etching, and packaging.（P58）

集成電路的主要的制造步驟包括薄膜形成、摻雜雜質(zhì)、微影技術(shù)、蝕刻、包裝。

13.Factory assembly line machinery is activated and monitored by a single PLC, where in the past hundreds of timers and relays would have been required to do the task.The machine or system user rarely, if ever, interacts directly with the PLC’s program.When it is necessary to either edit or create the PLC program, a personal computer is usually(but not always)connected to it.(What is a PLC?)（P61）

工廠的裝配線機(jī)械用一個(gè) PLC 就能操縱和監(jiān)控，過(guò)去需要數(shù)百的計(jì)時(shí)器和繼電器才能完成這項(xiàng)工作。這臺(tái)機(jī)器或系統(tǒng)用戶，如果有的話，很少直接與 PLC 的程序交互。當(dāng)有必要編輯或創(chuàng)建PLC程序時(shí)僅需將個(gè)人計(jì)算機(jī)（但不總是）連到 PLC 上。

14.The processes of sequencing control and interlock logic needed for automobile manufacturing was a time consuming and arduous task, which required manual updating of relays, timers and dedicated closed-loop controllers.When a new year’s model was coming off the drawing board, skilled electricians were called on to reset the production line.(What is a PLC?)（P61）汽車(chē)制造所需的時(shí)序控制、互鎖邏輯的處理是一項(xiàng)耗時(shí)、費(fèi)勁的工作，它需要手工更新繼電器、計(jì)時(shí)器和特定的閉環(huán)控制器。當(dāng)一個(gè)新年度模型脫離制圖板，熟練的電工被要求從裝生產(chǎn)線。

15.PLCs, in essence, monitor external sensory activity from additional devices.They take in the data which reports on a wide variety of activity, such as machine performance, energy output, and process impediment.They also control attached motor starters, pilot lights, values and many other devices.Both functions respond to a custom, user-created program.(What is a PLC?)（P62）

PLC，本質(zhì)上是監(jiān)控附加裝置的外部傳感活動(dòng)，他們接受數(shù)據(jù)，這些數(shù)據(jù)提供廣泛的活動(dòng)，如機(jī)器性能、能量輸出和加工障礙。它們也控制相連的馬達(dá)啟動(dòng)器、導(dǎo)航燈、閥門(mén)和許多其他裝置。所有的功能都對(duì)應(yīng)一個(gè)慣例，實(shí)用程序。

16.They(PLCs)are designed for real-time use, and often must withstand harsh environments on the shop floor.The programmable logic controller circuitry monitors the status of multiple sensor input, which control output actuators, which may be things like motor starters, solenoid, lights and displays, or valves.(What is a PLC?)（P62）

PLC 被設(shè)計(jì)為實(shí)時(shí)應(yīng)用，常常必須經(jīng)受車(chē)間惡劣環(huán)境。PLC的電路檢測(cè)很多傳感器輸入的狀態(tài)，控制輸出執(zhí)行機(jī)構(gòu)，如馬達(dá)啟動(dòng)器、螺線管、燈、顯示屏和閥門(mén)。

17.Ladder logic is essentially a Boolean logic-solving program with a graphical user interface designed to look like an elementary wiring diagram, familiar to all industrial electricians.(What is a PLC?)（P62）

梯形邏輯本質(zhì)是一個(gè)具有圖形用戶界面的布爾邏輯處理程序，設(shè)計(jì)成一個(gè)所有的工業(yè)電氣師都熟悉的基本電氣線圖。

18.PID can be described as a set of rules with which precise regulation of a closed-loop control system is obtained.Closed loop control means a method in which a real-time measurement of the process being controlled is constantly fed back to the controlling device to ensure that the value which is desired is, in fact, being realized.(What is PID Control)（P63）

PID可以用一組規(guī)則描述，通過(guò)這組規(guī)則可獲得閉環(huán)控制系統(tǒng)的精密調(diào)控。閉環(huán)控制是一種方法，用這種方法可將被控過(guò)程的實(shí)時(shí)檢測(cè)持續(xù)地反饋給控制設(shè)備以確保期望值被實(shí)現(xiàn)。

19.The most important of these(PIDs), Proportional Control, determines the magnitude of the difference between the SETPOINT and the PROCESS VARIABLE(known as ERROR), and then applies appropriate proportional changes to the CONTROL VARIABLE to eliminate ERROR.(What is PID Control)（P63）

PID中最重要的是比例控制，它決定了設(shè)定值和過(guò)程變量間的差值，然后對(duì)控制變量使用合適的比例變量以消除誤差。

20.Shafting is the machine element that supports a roller and wheel so that they can perform their basic functions of rotation.Shafting, made from round metal bars of various lengths and machined to dimension the surface, is used in a great variety of shapes and applications.Because shafts carry loads and transmit power, they are subject to the stresses and strains of operating machine parts.Standardized procedures have been evolved for determining the material characteristics and size requirements for safe and economical construction and operation.(Shafting)（P67）

軸是能支撐滾子和輪子以完成最基本的旋轉(zhuǎn)運(yùn)動(dòng)的機(jī)械元件。軸，由各類長(zhǎng)度的圓形金屬棒料制成，被加工成各類的表面尺寸，以各種形狀用于各種用途。軸因?yàn)槌休d和傳動(dòng)必經(jīng)受在工作的機(jī)器零件的應(yīng)力和應(yīng)變。已演化出的標(biāo)準(zhǔn)流程確定安全經(jīng)濟(jì)結(jié)構(gòu)操作所需的材料特性和尺寸要求。

21.Particularly in solid shafting, the shaft is stepped to allow greater strength in the middle portion with minimum diameter on the ends at the bearings.The steps allow shoulders for positioning the various parts pressed onto the shaft during the rotor assembly.(Shafting)（P67）特別是實(shí)心軸，階梯軸允許中部有更大的強(qiáng)度，端部軸承處直徑最小。階梯允許軸肩在轉(zhuǎn)子裝置期間，通過(guò)靠在軸上來(lái)定位各類零件。

22.One or more pieces of shafting joined by couplings is used to transmit power from, for example, an engine to a remotely located machine.A single engine can drive many lines of shafting, which, in turn, connect in multiple fashions to process equipment machines.Belts operate on pulleys to transmit the torque from one line to another and from the shafting to the machines.Clutches and couplings control the transfer of power from the shafting.The delivery of power to the machines in a shop has generally been converted from line shafting to individual electric motor drives for each machine.Thus, in a modern processing plant, line shafting is obsolete.（P68）

一個(gè)或多個(gè)傳動(dòng)軸件，由聯(lián)軸節(jié)接合，用來(lái)傳送能量形式，例如，一個(gè)引擎到遠(yuǎn)程機(jī)器。一個(gè)單一的引擎可以驅(qū)動(dòng)許多軸系，反過(guò)來(lái)，以多種形式連接到加工設(shè)備機(jī)器。皮帶在滑輪上運(yùn)行，從一個(gè)軸系向另一個(gè)軸系傳遞扭矩，并從軸系傳遞給機(jī)器。離合器和聯(lián)軸器控制來(lái)自軸系的動(dòng)力傳遞。

把動(dòng)力傳遞給車(chē)間里的機(jī)器一般已從用傳動(dòng)軸系變成了用獨(dú)立的電動(dòng)馬達(dá)驅(qū)動(dòng)每臺(tái)機(jī)器。因此，在一個(gè)現(xiàn)代化的加工廠里，傳動(dòng)軸系已過(guò)時(shí)。

23.Differing widely in viscosity, specific gravity, vapor pressure, boiling point, and other properties, lubricants also offer a wide range of selection for the increasingly varied needs of modern industry.But whatever their derivation or properties, the purpose of lubricants is to replace dry friction with either thin-film or fluid-film friction, depending on the load, speed, or intermittent action of the moving parts.Thin-film lubrication, in which there is some contact between the moving parts, usually is specified where heavy loads are a factor.(Lubrication)（P76）

潤(rùn)滑劑在粘度、比重、蒸汽壓、沸點(diǎn)和其他特性廣泛不同，潤(rùn)滑劑為現(xiàn)代工業(yè)的漸長(zhǎng)的各種需求提供廣泛的選擇。但無(wú)論它們的來(lái)源和特性是什么，潤(rùn)滑劑的目的是按移動(dòng)部件的載荷、速度或間歇運(yùn)動(dòng)，用薄膜或流體膜摩擦取代干摩擦。薄膜潤(rùn)滑是指移動(dòng)部件之間有部分接觸，通常特指的重載荷是一個(gè)影響因素。

24.To keep the parts separated, it is necessary that the pressure within the lubricating film balances the load on the sliding surfaces.If the lubricating film’s pressure is supplied by an external source, the system is said to be lubricated hydrostatically.If the pressure between the surface is generated as a result of the shape and motion of the surfaces themselves, however, the system is hydrodynamically lubricated.This second type of lubrication depends upon the viscous properties of the lubricants.(Lubrication)（P77）

要保證零件相互分離，必須是潤(rùn)滑油膜內(nèi)的壓力與滑動(dòng)表面的載荷平衡。如果潤(rùn)滑油膜的壓力是由外部源提供，則系統(tǒng)被稱為流體靜壓潤(rùn)滑。如果表面之間的壓力是由表面形狀和表面運(yùn)動(dòng)而形成的結(jié)果，然而這系統(tǒng)被稱為流體動(dòng)壓潤(rùn)滑。第二種潤(rùn)滑方法取決于潤(rùn)滑劑的粘性。

25.A condition that lies between unlubricated sliding and fluid-film lubrication is referred to as boundary lubrication, also defined as that condition of lubrication in which the friction between surfaces is determined by the properties of the surfaces and properties of the lubricant other than viscosity.Boundary lubrication encompasses a significant portion of lubrication phenomena and commonly occurs during the starting and stopping of machines.(Lubrication)（P77）潤(rùn)滑狀態(tài)介于干摩擦與油膜潤(rùn)滑之間的被稱為邊界潤(rùn)滑，其潤(rùn)滑狀態(tài)也被定義為表面之間的的摩擦是由表面的特性、潤(rùn)滑油粘度之外的其它特性所決定的。邊界潤(rùn)滑在潤(rùn)滑現(xiàn)象中占據(jù)相當(dāng)大的比重，并且通常發(fā)生在機(jī)器啟動(dòng)和制動(dòng)階段。

26.Shops often overlook vibration issues when installing machine tools or equipment.However, planning for vibration control, optimally before constructing a new facility or during redesign of an existing one, can save shops a lot of money in the long run.That’s because isolating machines and processes from unwanted vibration reduces future problems such as bad part-surface finished, parts out of tolerance, and even physiological damage to shop personnel.(Isolating Unwanted Vibration)（P93）

車(chē)間常在安裝機(jī)床或設(shè)備時(shí)忽視震動(dòng)問(wèn)題。然而，最好在構(gòu)造一個(gè)新設(shè)施或從新在設(shè)計(jì)一個(gè)現(xiàn)有的設(shè)施之前理想規(guī)劃震動(dòng)控制，這可從長(zhǎng)遠(yuǎn)利益上為車(chē)間節(jié)省許多費(fèi)用。這因?yàn)閷C(jī)器和加工從有害震動(dòng)中隔離可減少未來(lái)的問(wèn)題，如避免低的零件表面精度，零件超公差，甚至工作人員的生理?yè)p害。

27.Some equipment manufacturers provide allowable-vibration specifications for their machines, but most don’t, which makes choosing an isolator system difficult.The key is knowing the amplitudes of vibration frequencies that harm machinery.Fabreeka reports this is where savvy companies call in a consultant or company specializing in vibration protection.(Isolating Unwanted Vibration)（P95）

部分設(shè)備制造商給機(jī)器提供震動(dòng)許用指標(biāo)，但多數(shù)不提供，這使得選擇隔離系統(tǒng)困難，關(guān)鍵是了解損害機(jī)械的震動(dòng)頻率的幅值。Fabreeka報(bào)告說(shuō)聰明點(diǎn)的公司聘請(qǐng)了專業(yè)做震動(dòng)防護(hù)的顧問(wèn)或公司。

28.Such specialists measure vibration with highly accurate instrumentation such as real-time signal analyzers.These devices capture raw data, without bias, for post-processing and quantify amplitude and frequency of vibration.With this data, the specialist recommends the best isolation solution.Engineers then conduct acceptance test measurements after installation to verify amplitudes and the resultant transmitted vibration.(Isolating Unwanted Vibration)（P95）這類專家用高精準(zhǔn)設(shè)備檢測(cè)震動(dòng)，如實(shí)時(shí)信號(hào)分析儀。這些設(shè)備不是真地捕獲原始數(shù)據(jù)，為了后處理和量化震動(dòng)的頻率和幅值。用這些數(shù)據(jù)，專家推薦最佳的隔離方案。工程師再在安裝后進(jìn)行驗(yàn)收測(cè)試測(cè)量，驗(yàn)證幅值和由此產(chǎn)生的傳送震動(dòng)。

29.The tooling and grippers are not part of the robotic system itself;rather, they are attachments that fit on the end of the robot’s arm.These attachments connected to the end of the robot’s arm allow the robot lift parts, spot-weld, paint, arc-weld, drill, beburr, and do a variety of tasks, depending on what is required of the robot.(P135)工具及夾爪并非歸屬于機(jī)器人系統(tǒng)的本身部分，而它們是裝在機(jī)器人手臂端部的附件。這些與機(jī)器人手臂端部相連接的附件，能使機(jī)器人提起零件、點(diǎn)焊、噴漆、弧焊、鉆孔、去毛刺，還可以根據(jù)所提要求執(zhí)行各種類型的任務(wù)。

30.The robotic system can also control the work cell of the operating robot.The work cell of the robot is the total environment in which the robot must perform its task.Included within this cell may be the controller, the robot manipulator, a working table, safety features, or a conveyor.All the equipment that is required in order for the robot to do its job is included in the work cell.In addition, signals form outside devices can communicate with the robot in order to tell the robot when it should assemble parts, pick up parts, or unload parts to a conveyor.(Robot)（P135）機(jī)器人系統(tǒng)也能控制操作機(jī)器人的工作單元。機(jī)器人的工作單元是機(jī)器人須執(zhí)行其任務(wù)的總環(huán)境。在這個(gè)單元內(nèi)包含有控制器、機(jī)械手、工作臺(tái)、安裝裝置或傳送帶。為機(jī)器人完成該工作所需的所有設(shè)備被包括在該單元內(nèi)。另外，外部設(shè)備的控制信號(hào)可和機(jī)器人通信，告知機(jī)器人何時(shí)應(yīng)當(dāng)裝配零件、拿起零件或卸載零件到傳送帶。

31.At the end of the arm, a wrist is connected.The wrist is made up of addition axes and a wrist flange.The wrist flange allows the robot user to connect different tooling to the wrist for different jobs.（P136）

在手臂的端部連接著一個(gè)手腕。該手腕由附加軸及手腕法蘭組成。該手腕法蘭允許機(jī)器人用戶根據(jù)不同的工作在手腕連接不同的工具。

第二篇：機(jī)械工程專業(yè)英語(yǔ)_翻譯

spark-igniton engine 電火花式發(fā)動(dòng)機(jī) acceptance sampling 認(rèn)可采樣 accessing 訪問(wèn) accurate 準(zhǔn)確的 acoustic 聲學(xué)的 actuator 作動(dòng)器 alternator 交流發(fā)動(dòng)機(jī) analog sensor 模擬傳感器

analog-to-digital converter 模數(shù)轉(zhuǎn)換器 armature 電樞

Artificial intelligence 人工智能 artificial neural networks 神經(jīng)網(wǎng)絡(luò) as a general rule of thumb 按慣例 assumption 假設(shè)

asynchronous AC motors 異步交流電動(dòng)機(jī)asynchronous 不同時(shí)的，異步的 bargains 討價(jià)還價(jià) bear on 生成 binomial 二項(xiàng)的 Brake system 制動(dòng)系統(tǒng)

brushed/brushless motors 有刷/無(wú)刷電機(jī) built into 內(nèi)建

By the same token 出于同樣的原因 capacitor Start 電容器啟動(dòng)（電動(dòng)機(jī)）catastrophically 毀滅性地 charging circuit 充電電路 Charging system 供電系統(tǒng) chassis 車(chē)身底盤(pán)

compression-ignition engine 壓然式發(fā)動(dòng)機(jī) coil high-tension cables 線圈高壓電纜 compartment 間隔間，車(chē)廂 Compound wound 復(fù)勵(lì) concerned with 與有關(guān) concise 簡(jiǎn)潔

conductivity 傳導(dǎo)率constant load 定常負(fù)載 contracts 合同 Converter 轉(zhuǎn)換器

corporate activities 公司的行為 credited letters 對(duì)賬單 cylinder 汽缸

data acquisition 數(shù)據(jù)拾取defectives 缺陷產(chǎn)品 derived from 起源于

destructive inspection 有損檢測(cè) Detect 檢測(cè)

diesel/compression-ignition engine 柴油機(jī) Differential 差速器

dimensions of parts 零件的尺寸 dissipate 耗盡，用完 distribution 分發(fā) distributor 分電器

downgrade to a lower quality level 信用等級(jí)下調(diào) dynamic braking 動(dòng)態(tài)制動(dòng)

Electricalsystem 電氣系統(tǒng)electrical equipment 電氣裝置 electrical schematics 電氣原理圖 electrical system 供電系統(tǒng)

electromechanical system 機(jī)電系統(tǒng)electromechanical 機(jī)電的 eliminate 排除 emphasis on 強(qiáng)調(diào) equivalent 相等的 Essential 基本的 establish 建立

expert system 專家系統(tǒng)

fiber-optic sensor 光纖傳感器fiber-optic sensors 光纖傳感器 Fiber-optic 光纖 field service 現(xiàn)場(chǎng)服務(wù) flaws 有缺點(diǎn)的 flux 通量 flywheel 飛輪

fractional horsepower(rating)小功率電動(dòng)機(jī) fractional 部分的，分?jǐn)?shù)的 functional 功能的gasoline/spark-ignition engine 汽油機(jī) Gas-turbine engine汽輪機(jī) generate 產(chǎn)生 geographic 地理的Gross domestic product 總產(chǎn)值heat engines 熱機(jī) high-tension 高壓的 hood（發(fā)動(dòng)機(jī)）罩 humidity 濕度 hyperbolic 雙曲線的hysteresis motors磁滯式電動(dòng)機(jī) hysteresis 滯后作用，磁滯式 hysteresis:磁滯現(xiàn)象ignition coil 點(diǎn)火線圈Ignition system點(diǎn)火系統(tǒng) imbalance 不平衡，不均衡 imperfect 不合格的 impetus 推動(dòng)，激勵(lì) in terms of 根據(jù)

increase or decrease the slip speed of the rotor 增減轉(zhuǎn)子的滑動(dòng)速率

induction motor 感應(yīng)式電機(jī) induction 電磁感應(yīng)

information technologies 信息技術(shù) inherent 固有的initial impetus 最初的發(fā)展 Inorganic materials 無(wú)機(jī)材料 inspect 檢查

Instrument servo motor 儀表伺服電機(jī) internal combustion engine 內(nèi)燃機(jī)

internal combustion 內(nèi)燃機(jī) invoices 發(fā)票

irreversible 不可逆轉(zhuǎn)的leading power factor 超前功率因數(shù) load torque負(fù)載扭矩Logicf unction 邏輯功能 logistic support 后勤保障 log-normal 對(duì)數(shù)正態(tài)的 low-tension 低壓的 Magnetic slip 電磁轉(zhuǎn)差率 maintained 保留 makes up for 彌補(bǔ) manipulate 操縱 marginal cost 邊際成本 medium 中間，媒介

mercury thermometer 水銀溫度計(jì) Missile flight tracking導(dǎo)彈飛性追蹤 moment of inertia 轉(zhuǎn)動(dòng)慣量 monitoring 監(jiān)視

motor winding電機(jī)繞組：

national codes and standards 國(guó)標(biāo) negotiate 談判

nondestructive inspection 無(wú)損檢測(cè) nondestructive 無(wú)損檢測(cè)

Nonmentallicmaterials非金屬材料 operating practice 實(shí)際操作 permanent magnet 永磁

permanent split capacitor 固定分相的電容器 permeability 滲透性 places the order 下訂單 Poisson distributions 泊松分布 Polar inertia極慣性矩poly-phase AC motors 多相交流電動(dòng)機(jī) polyphase 多相的 Power factor功率因數(shù)

Price-performance ratio 性價(jià)比 Principal component 主要部件 proximity sensor 接近傳感器 purchase order 訂單 quality assurance 質(zhì)量保證 quality in conformance 產(chǎn)品移植性 raw materials 原材料 Rear wheel drive后輪驅(qū)動(dòng)

regenerative braking 再生制動(dòng)，反饋制動(dòng) regenerative 再生的，反饋的reluctance 磁阻repulsion induction 推斥式感應(yīng)repulsion start 推斥式啟動(dòng) reversible 可逆的 Rotational speed轉(zhuǎn)速

rotor magnetic field rotate 轉(zhuǎn)子磁場(chǎng)運(yùn)動(dòng) sampling 采樣 scheme 安排

schemes 方案 scrapped 拋棄

semi-finished parts 半成品 sensor fusion 傳感器融合Series wound串勵(lì)shaded pole 屏蔽極式 Sheet metal shell金屬板殼 Shunt wound并勵(lì) Shut-off關(guān)斷

signs the agreement 簽合同 single phase 單相的 smart sensor 智能傳感器 somewhat 稍微，有點(diǎn)

sophistication 復(fù)雜性，完善化，采用先進(jìn)技術(shù)spark plug cables 火花塞電纜 spark plug 火花塞 specifications 指標(biāo)

speed transducer 速度傳感器 split phase 分相式 squirrel cage 鼠籠式

Starting system 啟動(dòng)系統(tǒng)statistical 統(tǒng)計(jì)的 統(tǒng)計(jì)學(xué) 統(tǒng)計(jì)學(xué)的 steering systems 方向系統(tǒng) steering 轉(zhuǎn)向器 stepper motors 步進(jìn)電機(jī) strain 應(yīng)變 sufficient 足夠的surface treatment 表面處理surroundings 環(huán)境

Suspension system懸掛系統(tǒng) suspension 懸架

switch 開(kāi)關(guān)，轉(zhuǎn)換器synchronous AC motors 同步交流電動(dòng)機(jī) synchronous 同時(shí)的Tactile sensing 觸覺(jué)傳感技術(shù) technique-based decision 技術(shù)決策 tends to 傾向于 tenet 原則

tensile tests 拉伸實(shí)驗(yàn) tensile 可拉長(zhǎng)的 tensile 張力，拉力

the induction motor operates near the ferquency of the input source：感應(yīng)式電動(dòng)機(jī)在接近輸入電源頻率下運(yùn)行。The internal combustion engine 內(nèi)燃機(jī) Tolerance levels公差等級(jí) Torque 扭矩

torque-speed curves 轉(zhuǎn)矩-速度曲線 traceability 可描繪

traditional business 傳統(tǒng)商務(wù) transmission systems 傳動(dòng)系統(tǒng) transmission 變速器 trunk deck 行李箱蓋

two-value capacitor start 兩價(jià)電容器啟動(dòng)

ubiquitous 普遍存在的 ultrasonic 超聲的，超聲波 universal motor 交直流兩用電動(dòng)機(jī) utilize 利用

variability 可變的 可變性 vehicle 車(chē)輛

Visual sensing視覺(jué)傳感技術(shù) voltage regulator 電壓調(diào)整器 Weight distribution 質(zhì)量分配 Winding current繞住電流

with the emergence of digital signal processors and microcontrollers 隨著數(shù)字信號(hào)處理器和控制器的出現(xiàn) wound rotor induction motor繞線轉(zhuǎn)子電動(dòng)機(jī) wound rotor 繞線轉(zhuǎn)子

第三篇：機(jī)械工程專業(yè)英語(yǔ)文章翻譯

機(jī)

械 題目：學(xué)號(hào)：班級(jí)：數(shù)控姓名：康振平

工 程 專 業(yè) 英 語(yǔ)

Computer-Aided Design and Manufacturing 20110334304 121

Computer-Aided Design and Manufacturing

計(jì)算機(jī)輔助設(shè)計(jì)與制造

Computer-aided design（CAD）involves the use of computers to create design drawings and product models.Computer-aided design is usually associated with interactive computer graphics（known as a CAD system）.Computer-aided design systems are powerful tools and are used in the mechanical design and geometric modeling of products and components.計(jì)算機(jī)輔助設(shè)計(jì)（CAD）是指用計(jì)算機(jī)來(lái)創(chuàng)造設(shè)計(jì)圖紙和產(chǎn)品模型。計(jì)算機(jī)輔助設(shè)計(jì)通常是與交互式計(jì)算機(jī)圖形學(xué)（稱為CAD系統(tǒng)）有關(guān)系的。計(jì)算機(jī)輔助設(shè)計(jì)系統(tǒng)是功能強(qiáng)大的工具，被用于在機(jī)械設(shè)計(jì)以及產(chǎn)品和零件的幾何建模。

In CAD，the drawing board is replaced by electronic input and output devices.When using a CAD system，the designer can conceptualize the object to be designed more easily on the Graphics screen and can consider alternative designs or modify a particular design quickly to meet the necessary design requirements or changes.The designer can then subject the design to a variety of engineering analyses and can identify potential problems（such as an excessive load or deflection）.The speed and accuracy of such analyses far surpass what is available from traditional methods.在CAD（計(jì)算機(jī)輔助設(shè)計(jì)）中，傳統(tǒng)的畫(huà)圖板被電子輸入和輸出設(shè)備所替換。當(dāng)使用CAD系統(tǒng)時(shí)，設(shè)計(jì)者可以使對(duì)象概念化以便更容易在圖形屏幕上設(shè)計(jì)，并且可以考慮替代設(shè)計(jì)或快速地修改一個(gè)特定的設(shè)計(jì)來(lái)達(dá)到必要的設(shè)計(jì)要求或變化。因而設(shè)計(jì)者可以提供多種工程分析并且可以識(shí)別潛在的問(wèn)題（如過(guò)負(fù)荷或變形）。這些分析的速度和準(zhǔn)確性都遠(yuǎn)遠(yuǎn)超過(guò)了傳統(tǒng)的方法。

Draft productivity rises dramatically.When something is drawn once，it never has to be drawn again.it can be retrieved from a library ,and can be duplicated, stretched, sized, and changed in many ways without having to be redrawn。Cut and paste techniques are used as labor-saving aids.設(shè)計(jì)生產(chǎn)率的提高是顯著的。當(dāng)某些圖形被繪制一次后，就沒(méi)必要再畫(huà)第二次。它可以從圖形庫(kù)中恢復(fù)，可以被復(fù)制，拉伸，改變大小，和其他許多方面的改變而無(wú)需重新繪制。剪切和粘貼技巧作為節(jié)省勞力的助手被使用。

CAD makes possible multiview 2D drawings，and the drawings can be reproduced in different levels of reduction and enlargement.It gives the mechanical engineer the ability to magnify even the smallest of components to ascertain if assembled components fit properly.Parts with different characteristics，such as movable or stationary，can be assigned different colors on the display.CAD使二維圖紙多重視圖變?yōu)榭赡?，并且圖形可以在大小不同的圖層里重生。它使機(jī)械工程師有能力放大甚至最小的部件來(lái)確定構(gòu)件是否裝配合適。對(duì)于具有不同特性的零部件，如移動(dòng)或靜止，可以指定不同的顏色在顯示屏上標(biāo)示。

have even more freedom with the advent of 3-D parts and manipulate them in endless variations to achieve the desired results.Through finite element analysis，stresses can be applied to be a computer model and the results graphically displayed，giving the designer quick feedback on any inherent problems in a design before the creation of a physical prototype.隨著三維建模的出現(xiàn)設(shè)計(jì)師有了更多自由和無(wú)限制的修改它們以實(shí)現(xiàn)所期望的結(jié)果。通過(guò)有限元分析，應(yīng)力加到計(jì)算機(jī)模型上并且以圖形化的方式顯示其結(jié)果，在產(chǎn)品物理原型生產(chǎn)之前，對(duì)設(shè)計(jì)中的任何內(nèi)在問(wèn)題給設(shè)計(jì)者一個(gè)快速的反饋。Designers In addition to the design’s geometric and dimensional features，other information（such as a list of materials，specification，and manufacturing instructions）is stored in the CAD database.Using such information ,the designer can then analyze the economics of alternative designs.除了設(shè)計(jì)的幾何和尺寸特性之外，其他信息(比如材料清單、規(guī)格、和制造說(shuō)明)都存儲(chǔ)在CAD數(shù)據(jù)庫(kù)里。利用這些信息，設(shè)計(jì)師可以分析備選設(shè)計(jì)的經(jīng)濟(jì)性。Computer-aided manufacturing(CAM)involves the uses of computers and computer technology to assist in all the phases of manufacturing a product，including process and production planning，machining，scheduling，management，and quality control.Computer-aided design and computer-aided manufacturing are often combined into CAD/CAM systems.計(jì)算機(jī)輔助制造(CAM)包括使用計(jì)算機(jī)和計(jì)算機(jī)技術(shù)來(lái)協(xié)助制造產(chǎn)品的所有階段，包括工藝和生產(chǎn)計(jì)劃，加工，調(diào)度，管理，和質(zhì)量控制。計(jì)算機(jī)輔助設(shè)計(jì)和計(jì)算機(jī)輔助制造常常是和CAD / CAM系統(tǒng)相結(jié)合的。

This combination allow the transfer of information from the design stage into the stage of

planning for the manufacture of a product，without the need to reenter the data on part geometry manually.The database developed during CAD is stored； then it is processed further，by CAM，into the necessary data and instructions for operating and controlling production machinery，material-handling equipment，and automated testing and inspection for product quality.這種組合允許一個(gè)產(chǎn)品的信息從設(shè)計(jì)階段傳遞到加工規(guī)劃階段，而不需要手動(dòng)重新輸入幾何部件的數(shù)據(jù)。計(jì)算機(jī)輔助設(shè)計(jì)研發(fā)期間存儲(chǔ)在數(shù)據(jù)庫(kù)，然后通過(guò)計(jì)算機(jī)輔助制造進(jìn)一步處理，一直到必要的數(shù)據(jù)和指令的操作和控制生產(chǎn)機(jī)械、物料搬運(yùn)設(shè)備，自動(dòng)化測(cè)試和檢驗(yàn)產(chǎn)品質(zhì)量。

In machining operations，an important feature of CAD/CAM is its capability to describe the tool path for various operations，such as NC turning，milling，and drilling.The instructions（programs）are computer generated，and they can be modified by the programmer to optimize the tool path.The engineer or technician can then display and visually check the tool path for possible tool collisions with fixtures or other interferences.The tool path can be modified at any time，to accommodate other part shapes to be machined.在機(jī)械加工中，CAD/CAM的一個(gè)重要特征是它有可以描述刀具運(yùn)動(dòng)軌跡的能力，如數(shù)控車(chē)削，銑削，鉆孔。指令（程序）是計(jì)算機(jī)生成的，它們可以由程序員修改優(yōu)化刀具路徑。工程師或技術(shù)員可以顯示和檢查刀具路徑可能與夾具或其他干擾工具碰撞。刀具路徑可以隨時(shí)修改，以適應(yīng)其他部分的形狀被加工。

Some typical applications of CAD/CAM are：（a）programming for NC，CNC，and industrial robots；（b）design of tools and fixtures and EDM electodes；（c）quality control and inspection，for instance，coordinate-measuring machines programmed on a CAD/CAM workstation；（d）process planning and scheduling ；and（e）plant layout.CAD / CAM的一些典型應(yīng)用是：（a）數(shù)控編程，計(jì)算機(jī)數(shù)控編程和工業(yè)機(jī)器人；（b）工具和夾具以及電火花電極的設(shè)計(jì)；（c）質(zhì)量控制和檢查，例如，在CAD / CAM工作站上的坐標(biāo)測(cè)量機(jī)編程；（d）工藝規(guī)劃與調(diào)度；和（e）工廠布局。

The emergence of CAD/CAM has had a major impact on manufacturing，by standardizing product development and by reducing design effort，tryout，and prototype work；it has made possible significantly reduced costs and improved productivity.The two-engine Boeing 777 passenger airplane，for example, was designed completed by computer（paperless design）.The plane is constructed directly from the CAD/CAM software developed（an enhanced CATIA system）and no prototypes or mockups were built，such as were required for previous models.CAD/CAM的出現(xiàn)對(duì)制造業(yè)產(chǎn)生了重大影響，通過(guò)產(chǎn)品開(kāi)發(fā)的標(biāo)準(zhǔn)化和減少設(shè)計(jì)工作量，試用，和原型的工作；它有可能大大降低成本和提高生產(chǎn)力。例如雙引擎的波音777客機(jī)就是由計(jì)算機(jī)設(shè)計(jì)完成（無(wú)紙化設(shè)計(jì)）。這架飛機(jī)直接從CAD/CAM軟件開(kāi)發(fā)（增強(qiáng)CATIA系統(tǒng)）并沒(méi)有建立原型或?qū)嵨锬Ｐ偷那闆r下制造出來(lái)，如以前所需要的的模型。

第四篇：機(jī)械工程專業(yè)英語(yǔ)唐一平翻譯

Unit1 1.2Ferrous Metals and Alloys By virtue of their wide range of mechanical, physical, and chemical properties, ferrous metals and alloys are among the most useful of all metals.Ferrous metals and alloys contain iron as their base metal: the general categories are cast irons, carbon and alloy steels, stainless steels, tool and die steels.1.2黑色金屬及其合金：

由于它們的一系列廣泛的機(jī)械物理和化學(xué)的特征，黑色金屬及其合金是所有金屬中最有用的鐵是黑色金屬及其合金中的基本元素主要種類有鑄鐵，碳鋼，合金鋼，不銹鋼，工具鋼和磨具鋼

The term cast iron refers to a family of ferrous alloys composed of iron, carbon(ranging from 2.11% to about 4.5%),and silicon(up to about 3.5%).Cast irons are usually classified as follows: 1.Gray cast iron,or gray iron;2.Ductile cast iron, nodular cast iron, or spherical graphite cast iron;3.White cast iron;4.Malleable iron;5.Compacted graphite iron。（），它包含鐵碳（2.5%—4.5%）和硅（3.5%）鑄鐵的分類如下1.灰鑄鐵2.球墨鑄鐵3.白口鑄鐵4.可鍛鑄鐵5.如墨鑄鐵

The equilibrium phase diagram relevant to cast irons is shown in Fig.1.1,in which the right boundary is 100% carbon,that is pure graphite.The eutectic temperature is 1154hC(2109hF), and so cast irons are completely liquid at temperatures lower than those required for liquid steels.Consequently, iron with high carbon content can be cast at lower temperatures than can steels.有關(guān)鑄鐵的平衡相圖如圖1.1所示 其右邊界是100%的碳 那是純石墨，其共晶溫度是1154℃因此鑄鐵可以在比那些熔化鋼更低的溫度下完全液化所以含碳量較高的鑄鐵的澆注溫度比鋼低。

Carbon steels are generally classified by their proportion(by weight)of carbon content.1.Low-carbon steel, also called mild steel, has less than 1.30% carbon.It is generally used for common industrial products, such as bolts,nuts, sheet, plate, and tubes, and for machine components that do not require high strength.3.碳鋼：碳銅大體上是按碳含量的臂力來(lái)分類的

1）低碳鋼又叫做軟鋼其碳含量小于0.30%它用于普遍的工業(yè)產(chǎn)品，例如螺栓，螺母。鋼板，港片鋼管和那些強(qiáng)度要求不高的機(jī)器零件

Unit5 5.1 Introduction

Conventional machining is the group of machining operations that use single-or multi-point tools to remove material in the form of chips.Metal cutting involves removing metal through machining operations.Machining traditionally takes place on lathes, drill presses, and milling machines with the use of various cutting tools.Most machining has very low set-up cost compared with forming, molding, and casting processes.However, machining is much more expensive for high volumes.Machining is necessary where tight tolerances on dimensions and finishes are required.傳統(tǒng)機(jī)加工是利用單刃或多刃刀具以切削形式去除材料的（一組）加工方法。金屬切削就是利用機(jī)加工的方法去除材料，傳統(tǒng)機(jī)加工都是利用不用的刀具在車(chē)床，鉆床和銑床上進(jìn)行的，與成型加工，模壓制件和鑄造工藝相比，機(jī)加工的準(zhǔn)備成本還是比較低的。然而，如果是大批量生產(chǎn)，其成本要高得多，當(dāng)對(duì)零件的光潔度和尺寸公差要求較高時(shí)，機(jī)加工是必須的。

5.2 Turning and Lathe

Turning is one of the most common of metal cutting operations.In turning, a workpiece is rotated about its axis as single-point cutting tools are fed into it, shearing away excess material and creating the desired cylindrical surface.Turning can occur on both external and internal surfaces to produce an axially-symmetrical contoured part.Parts ranging from pocket watch components to large diameter marine propeller shafts can be turned on a lathe.5.1 車(chē)削與車(chē)床

沿工件進(jìn)給，切掉多余的材料，最后形成要求的圓柱型表面，車(chē)削可以加工外表面以形成軸對(duì)稱的成型零件，從懷表的零件到大型螺旋角零件軸都可以在車(chē)床上加工。

車(chē)削是金屬切削加工中最常用的方法之一。在車(chē)削過(guò)程中，一個(gè)工件繞其軸線回轉(zhuǎn)，單刃車(chē)刀 Apart from turning, several other operations can also be performed on a lathe.除了車(chē)削，一些其它的操作也可以在車(chē)床上完成。

Boring and internal turning.Boring and internal turning are performed on the internal surfaces by a boring bar or suitable internal cutting tools.If the initial workpiece is solid, a drilling operation must be performed first.The drilling tool is held in the tailstock, and the latter is then fed against the workpiece.When boring is done in a lathe, the work usually is held in a chuck or on a face plate.Holes may be bored straight, tapered, or to irregular contours.Boring is essentially internal turning while feeding the tool parallel to the rotation axis of the workpiece.鏜削和車(chē)內(nèi)圓：利用鏜桿或合適的內(nèi)圓車(chē)刀可以進(jìn)行鏜削和車(chē)內(nèi)圓。工件毛坯如果是實(shí)心的，首先要鉆孔，鉆頭安裝在尾架上，后者向工件進(jìn)給，如果在車(chē)床上進(jìn)行鏜削，工件一般安裝在卡盤(pán)活花盤(pán)上。鏜出的孔可以是盲孔、錐孔或者不規(guī)則的輪廓，當(dāng)工具與回轉(zhuǎn)軸平行進(jìn)給時(shí)，鏜削實(shí)際上是車(chē)削。

Unit7

Quality and accuracy are major considerations in making parts or structures.Interchangeable parts require a high degree of accuracy to fit together.With increasing accuracy or less variation in the dimension, the labor and machinery required to manufacture apart is more cost intensive.Any manufacturer should have a thorough knowledge of the tolerances to increase the quality and reliability of a manufactured part with the least expense.在制造機(jī)器零件和結(jié)構(gòu)的過(guò)程中，質(zhì)量和精度是最重要的因素。互換性零件需要有高精度以實(shí)現(xiàn)相互配合。隨著精度的增加和尺寸變化的減小，制造零件所需的勞動(dòng)力和機(jī)器更趨于成本密集型，制造商應(yīng)該對(duì)公差有全面的了解，并以最小的成本提高加工零件的質(zhì)量和可靠性。

An engineering drawing must be properly dimensioned in order to convey the designer’s intent to the end user.Dimensions of parts given on blueprints and manufactured to those dimensions should be exactly alike and fit properly.Unfortunately, it is impossible to make things to an exact or dimension.Most dimensions have a varying degree of accuracy and a means od specifying acceptable limitations in dimensional variance so that a manufactured part will be accepted and still function.It is necessary that the dimensions, shapes and mutual position of surfaces of individual parts are kept within a certain accuracy to achieve their correct and reliable functioning.Routine processes do not allow maintenance(or measurement)of the given geometrical properties with absolute accuracy.Actual surfaces of the produced parts therefore differ from ideal surfaces prescribed in drawings.Deviations of actual surfaces are divided into four groups to enable assessment, prescription and checking of the permitted inaccuracy during production: 1:Dimensional deviations;

2:Shape deviations;3:Position deviations;

4:Surface roughness deviations.一張工程圖應(yīng)有恰當(dāng)?shù)某叽鐦?biāo)注，來(lái)把設(shè)計(jì)師的想法傳遞給用戶，加工出的零件尺寸應(yīng)與圖紙上所標(biāo)注的零件尺寸完全一致并匹配，但是加工零件的尺寸不可能是精確的尺寸，大多數(shù)的尺寸都有一個(gè)加工范圍，這是可接受的規(guī)定尺寸變化極限的一種方法，以至于可以接受并使用這一加工零件，各個(gè)零件的尺寸精度，形狀精度，互換位置精度必須保持在一個(gè)精度范圍以內(nèi)，以便正確可靠的實(shí)現(xiàn)他們的功能，常規(guī)的加工過(guò)程不允許對(duì)具有絕對(duì)精度的給點(diǎn)的幾何特性進(jìn)行維修和測(cè)量，因此實(shí)際零件加工表面不同于圖紙中規(guī)定的理想零件表面，實(shí)際加工表面的偏差在進(jìn)行評(píng)估說(shuō)明和允許誤差的檢查過(guò)程中被分為四類：1.尺寸偏差，2.形狀偏差，3.位置偏差，4.表面粗糙度。

第五篇：機(jī)械工程英語(yǔ)第二版翻譯

第一單元

? Types of Materials

材料的類型

Materials may be grouped in several ways.Scientists often classify materials by their state: solid, liquid, or gas.They also separate them into organic(once living)and inorganic(never living)materials.材料可以按多種方法分類?？茖W(xué)家常根據(jù)狀態(tài)將材料分為：固體、液體或氣體。他們也把材料分為有機(jī)材料(曾經(jīng)有生命的)和無(wú)機(jī)材料(從未有生命的)。

For industrial purposes, materials are divided into engineering materials or nonengineering materials.Engineering materials are those used in manufacture and become parts of products.就工業(yè)效用而言，材料被分為工程材料和非工程材料。那些用于加工制造并成為產(chǎn)品組成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料則是化學(xué)品、燃料、潤(rùn)滑劑以及其它用于加工制造過(guò)程但不成為產(chǎn)品組成部分的材料。Engineering materials may be further subdivided into: ①M(fèi)etal ②Ceramics ③Composite ④Polymers, etc.工程材料還能進(jìn)一步細(xì)分為：①金屬材料②陶瓷材料③復(fù)合材料 ④聚合材料，等等。

? Metals and Metal Alloys 金屬和金屬合金

Metals are elements that generally have good electrical and thermal conductivity.Many metals have high strength, high stiffness, and have good ductility.金屬就是通常具有良好導(dǎo)電性和導(dǎo)熱性的元素。許多金屬具有高強(qiáng)度、高硬度以及良好的延展性。Some metals, such as iron, cobalt and nickel, are magnetic.At low temperatures, some metals and intermetallic compounds become superconductors.某些金屬能被磁化，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉(zhuǎn)變成超導(dǎo)體。

What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金與純金屬的區(qū)別是什么？純金屬是在元素周期表中占據(jù)特定位置的元素。例如電線中的銅和制造烹飪箔及飲料罐的鋁。

Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一種金屬元素。合金的性質(zhì)能通過(guò)改變其中存在的元素而改變。金屬合金的例子有：不銹鋼是一

種鐵、鎳、鉻的合金，以及金飾品通常含有金鎳合金。

Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.為什么要使用金屬和合金？許多金屬和合金具有高密度，因此被用在需要較高質(zhì)量體積比的場(chǎng)合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金屬合金，例如鋁基合金，其密度低，可用于航空航天以節(jié)約燃料。許多合金還具有高斷裂韌性，這意味著它們能經(jīng)得起沖擊并且是耐用的。

What are some important properties of metals? Density is defined as a material’s mass divided by its volume.Most metals have relatively high densities, especially compared to polymers.金屬有哪些重要特性？

密度定義為材料的質(zhì)量與其體積之比。大多數(shù)金屬密度相對(duì)較高，尤其是和聚合物相比較而言。Materials with high densities often contain atoms with high atomic numbers, such as gold or lead.However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由較大原子序數(shù)原子構(gòu)成，例如金和鉛。然而，諸如鋁和鎂之類的一些金屬則具有低密度，并被用于既需要金屬特性又要求重量輕的場(chǎng)合。

Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced.Metals can generally contain nicks and dents without weakening very much, and are impact resistant.A football player counts on this when he trusts that his facemask won’t shatter.斷裂韌性可以描述為材料防止斷裂特別是出現(xiàn)缺陷時(shí)不斷裂的能力。金屬一般能在有缺口和凹痕的情況下不顯著削弱，并且能抵抗沖擊。橄欖球運(yùn)動(dòng)員據(jù)此相信他的面罩不會(huì)裂成碎片。

Plastic deformation is the ability of bend or deform before breaking.As engineers, we usually design materials so that they don’t deform under normal conditions.You don’t want your car to lean to the east after a strong west wind.塑性變形就是在斷裂前彎曲或變形的能力。作為工程師，設(shè)計(jì)時(shí)通常要使材料在正常條件下不變形。沒(méi)有人愿意一陣強(qiáng)烈的西風(fēng)過(guò)后自己的汽車(chē)向東傾斜。

However, sometimes we can take advantage of plastic deformation.The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有時(shí)我們也能利用塑性變形。汽車(chē)上壓皺的區(qū)域在它們斷裂前通過(guò)經(jīng)歷塑性變形來(lái)吸收能量。The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and

electrical wires.金屬的原子連結(jié)對(duì)它們的特性也有影響。在金屬內(nèi)部，原子的外層階電子由所有原子共享并能到處自由移動(dòng)。由于電子能導(dǎo)熱和導(dǎo)電，所以用金屬可以制造好的烹飪鍋和電線。

It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因?yàn)檫@些階電子吸收到達(dá)金屬的光子，所以透過(guò)金屬不可能看得見(jiàn)。沒(méi)有光子能通過(guò)金屬。

Alloys are compounds consisting of more than one metal.Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一種以上金屬組成的混合物。加一些其它金屬能影響密度、強(qiáng)度、斷裂韌性、塑性變形、導(dǎo)電性以及環(huán)境侵蝕。

For example, adding a small amount of iron to aluminum will make it stronger.Also, adding some chromium to steel will slow the rusting process, but will make it more brittle.例如，往鋁里加少量鐵可使其更強(qiáng)。同樣，在鋼里加一些鉻能減緩它的生銹過(guò)程，但也將使它更脆。

? Ceramics and Glasses 陶瓷和玻璃

A ceramic is often broadly defined as any inorganic nonmetallic material． By this definition, ceramic materials would also include glasses;however, many materials scientists add the stipulation that “ceramic” must also be crystalline.陶瓷通常被概括地定義為無(wú)機(jī)的非金屬材料。照此定義，陶瓷材料也應(yīng)包括玻璃；然而許多材料科學(xué)家添加了“陶瓷”必須同時(shí)是晶體物組成的約定。

A glass is an inorganic nonmetallic material that does not have a crystalline structure.Such materials are said to be amorphous.玻璃是沒(méi)有晶體狀結(jié)構(gòu)的無(wú)機(jī)非金屬材料。這種材料被稱為非結(jié)晶質(zhì)材料。Properties of Ceramics and Glasses Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性

高熔點(diǎn)、低密度、高強(qiáng)度、高剛度、高硬度、高耐磨性和抗腐蝕性是陶瓷和玻璃的一些有用特性。

Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.許多陶瓷都是電和熱的良絕緣體。某些陶瓷還具有一些特殊性能：有些是磁性材料，有些是壓電材料，還有些特殊陶瓷在極低溫度下是超導(dǎo)體。陶瓷和玻璃都有一個(gè)主要的缺點(diǎn)：它們?nèi)菀灼扑椤?/p>

Ceramics are not typically formed from the melt.This is because most ceramics will crack extensively(i.e.form a powder)upon cooling from the liquid state.陶瓷一般不是由熔化形成的。因?yàn)榇蠖鄶?shù)陶瓷在從液態(tài)冷卻時(shí)將會(huì)完全破碎(即形成粉末)。

Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics.Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生產(chǎn)的簡(jiǎn)單有效的—諸如澆鑄和吹制這些涉及熔化的技術(shù)都不能用于由晶體物組成的陶瓷的生產(chǎn)。作為替代，一般采用“燒結(jié)”或“焙燒”工藝。

In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point.At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained.在燒結(jié)過(guò)程中，陶瓷粉末先擠壓成型然后加熱到略低于熔點(diǎn)溫度。在這樣的溫度下，粉末內(nèi)部起反應(yīng)去除孔隙并得到十分致密的物品。

An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光導(dǎo)纖維有三層：核心由高折射指數(shù)高純光傳輸玻璃制成，中間層為低折射指數(shù)玻璃，是保護(hù)核心玻璃表面不被擦傷和完整性不被破壞的所謂覆層，外層是聚合物護(hù)套，用于保護(hù)光導(dǎo)纖維不受損。

In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.為了使核心玻璃有比覆層大的折射指數(shù)，在其中摻入微小的、可控?cái)?shù)量的能減緩光速而不會(huì)吸收光線的雜質(zhì)或攙雜劑。

Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle.由于核心玻璃的折射指數(shù)比覆層大，只要在全內(nèi)反射過(guò)程中光線照射核心/覆層分界面的角度比臨界角大，在核心玻璃中傳送的光線將仍保留在核心玻璃中。

The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全內(nèi)反射現(xiàn)象與核心玻璃的高純度一樣，使光線幾乎無(wú)強(qiáng)度損耗傳遞長(zhǎng)距離成為可能。

? Composites

復(fù)合材料

Composites are formed from two or more types of materials.Examples include polymer/ceramic and metal/ceramic

composites.Composites are used because overall properties of the composites are superior to those of the individual components.復(fù)合材料由兩種或更多材料構(gòu)成。例子有聚合物/陶瓷和金屬/陶瓷復(fù)合材料。之所以使用復(fù)合材料是因?yàn)槠淙嫘阅軆?yōu)于組成部分單獨(dú)的性能。

For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.Two types of composites are: fiber-reinforced composites and particle-reinforced composites.例如：聚合物/陶瓷復(fù)合材料具有比聚合物成分更大的模量，但又不像陶瓷那樣易碎。復(fù)合材料有兩種：纖維加強(qiáng)型復(fù)合材料和微粒加強(qiáng)型復(fù)合材料。Fiber-reinforced Composites Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers.Fibers increase the modulus of the matrix material.纖維加強(qiáng)型復(fù)合材料

加強(qiáng)纖維可以是金屬、陶瓷、玻璃或是已變成石墨的被稱為碳纖維的聚合物。纖維能加強(qiáng)基材的模量。The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿著纖維長(zhǎng)度有很強(qiáng)結(jié)合力的共價(jià)結(jié)合在這個(gè)方向上給予復(fù)合材料很高的模量，因?yàn)橐獡p壞或拉伸纖維就必須破壞或移除這種結(jié)合。

Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.把纖維放入復(fù)合材料較困難，這使得制造纖維加強(qiáng)型復(fù)合材料相對(duì)昂貴。

Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix.纖維加強(qiáng)型復(fù)合材料用于某些最先進(jìn)也是最昂貴的運(yùn)動(dòng)設(shè)備，例如計(jì)時(shí)賽競(jìng)賽用自行車(chē)骨架就是用含碳纖維的熱固塑料基材制成的。

Body parts of race cars and some automobiles are composites made of glass fibers(or fiberglass)in a thermoset matrix.競(jìng)賽用汽車(chē)和某些機(jī)動(dòng)車(chē)的車(chē)體部件是由含玻璃纖維(或玻璃絲)的熱固塑料基材制成的。

Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis.Fiber composite manufacturers often rotate layers of fibers to avoid directional variations in the modulus.纖維在沿著其軸向有很高的模量，但垂直于其軸向的模量卻較低。纖維復(fù)合材料的制造者往往旋轉(zhuǎn)纖維層以防模量產(chǎn)生方向變化。

Particle-reinforced composites Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as

aluminum, and amorphous materials，including polymers and carbon black.微粒加強(qiáng)型復(fù)合材料

用于加強(qiáng)的微粒包含了陶瓷和玻璃之類的礦物微粒，鋁之類的金屬微粒以及包括聚合物和碳黑的非結(jié)晶質(zhì)微粒。

Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix.An example of particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.微粒用于增加基材的模量、減少基材的滲透性和延展性。微粒加強(qiáng)型復(fù)合材料的一個(gè)例子是機(jī)動(dòng)車(chē)胎，它就是在聚異丁烯人造橡膠聚合物基材中加入了碳黑微粒。

? Polymers

聚合材料

A polymer has a repeating structure, usually based on a carbon backbone.The repeating structure results in large chainlike molecules.Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.聚合物具有一般是基于碳鏈的重復(fù)結(jié)構(gòu)。這種重復(fù)結(jié)構(gòu)產(chǎn)生鏈狀大分子。由于重量輕、耐腐蝕、容易在較低溫度下加工并且通常較便宜，聚合物是很有用的。

Some important characteristics of polymers include their size(or molecular weight), softening and melting points, crystallinity, and structure.The mechanical properties of polymers generally include low strength and high toughness.Their strength is often improved using reinforced composite structures.聚合材料具有一些重要特性，包括尺寸(或分子量)、軟化及熔化點(diǎn)、結(jié)晶度和結(jié)構(gòu)。聚合材料的機(jī)械性能一般表現(xiàn)為低強(qiáng)度和高韌性。它們的強(qiáng)度通常可采用加強(qiáng)復(fù)合結(jié)構(gòu)來(lái)改善。

Important Characteristics of Polymers Size.Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性

尺寸：?jiǎn)蝹€(gè)聚合物分子一般分子量為10,000到1,000,000g/mol之間，具體取決于聚合物的結(jié)構(gòu)—這可以比2,000個(gè)重復(fù)單元還多。

The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.聚合物的分子量極大地影響其機(jī)械性能，分子量越大，工程性能也越好。

Thermal transitions.The softening point(glass transition temperature)and the melting point of a polymer will determine which it will be suitable for applications.These temperatures usually determine the upper limit for which a polymer can be used.熱轉(zhuǎn)換性：聚合物的軟化點(diǎn)(玻璃狀轉(zhuǎn)化溫度)和熔化點(diǎn)決定了它是否適合應(yīng)用。這些溫度通常決定聚合物能否使用的上限。

For example, many industrially important polymers have glass transition temperatures near the boiling point of water(100℃, 212℉), and they are most useful for room temperature applications.Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).例如，許多工業(yè)上的重要聚合物其玻璃狀轉(zhuǎn)化溫度接近水的沸點(diǎn)(100℃, 212℉)，它們被廣泛用于室溫下。而某些特別制造的聚合物能經(jīng)受住高達(dá)300℃(572℉)的溫度。

Crystallinity.Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures(semi-crystalline).結(jié)晶度：聚合物可以是晶體狀的或非結(jié)晶質(zhì)的，但它們通常是晶體狀和非結(jié)晶質(zhì)結(jié)構(gòu)的結(jié)合物(半晶體)。Interchain interactions.The polymer chains can be free to slide past one another(thermo-plastic)or they can be connected to each other with crosslinks(thermoset or elastomer).Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子鏈間的相互作用：聚合物的原子鏈可以自由地彼此滑動(dòng)(熱可塑性)或通過(guò)交鍵互相連接(熱固性或彈性)。熱可塑性材料可以重新形成和循環(huán)使用，而熱固性與彈性材料則是不能再使用的。

Intrachain structure.The chemical structure of the chains also has a tremendous effect on the properties.Depending on the structure the polymer may be hydrophilic or hydrophobic(likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.鏈內(nèi)結(jié)構(gòu)：原子鏈的化學(xué)結(jié)構(gòu)對(duì)性能也有很大影響。根據(jù)各自的結(jié)構(gòu)不同，聚合物可以是親水的或憎水的(喜歡或討厭水)、硬的或軟的、晶體狀的或非結(jié)晶質(zhì)的、易起反應(yīng)的或不易起反應(yīng)的。

第二單元

The understanding of heat treatment is embraced by the broader study of metallurgy.Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product.對(duì)熱處理的理解包含于對(duì)冶金學(xué)較廣泛的研究。冶金學(xué)是物理學(xué)、化學(xué)和涉及金屬?gòu)牡V石提煉到最后產(chǎn)物的工程學(xué)。

Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties.According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining.熱處理是將金屬在固態(tài)加熱和冷卻以改變其物理性能的操作。按所采用的步驟，鋼可以通過(guò)硬化來(lái)抵抗切削和磨損，也可以通過(guò)軟化來(lái)允許機(jī)加工。

With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior.The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.使用合適的熱處理可以去除內(nèi)應(yīng)力、細(xì)化晶粒、增加韌性或在柔軟材料上覆蓋堅(jiān)硬的表面。因?yàn)槟承┰?尤其是碳)的微小百分比極大地影響物理性能，所以必須知道對(duì)鋼的分析。

Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper.Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.合金鋼的性質(zhì)取決于其所含有的除碳以外的一種或多種元素，如鎳、鉻、錳、鉬、鎢、硅、釩和銅。由于合金鋼改善的物理性能，它們被大量使用在許多碳鋼不適用的地方。

The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels.With this process the rate of cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect.下列討論主要針對(duì)被稱為普通碳鋼的工業(yè)用鋼而言。熱處理時(shí)冷卻速率是控制要素，從高于臨界溫度快速冷卻導(dǎo)致堅(jiān)硬的組織結(jié)構(gòu)，而緩慢冷卻則產(chǎn)生相反效果。

? A Simplified Iron-carbon Diagram 簡(jiǎn)化鐵碳狀態(tài)圖

If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力集中于一般所說(shuō)的鋼上，經(jīng)常要用到簡(jiǎn)化鐵碳狀態(tài)圖。

Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted.A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.鐵碳狀態(tài)圖中靠近三角區(qū)和含碳量高于2%的那些部分對(duì)工程師而言不重要，因此將它們刪除。如圖2.1所示的簡(jiǎn)化鐵碳狀態(tài)圖將焦點(diǎn)集中在共析區(qū)，這對(duì)理解鋼的性能和處理是十分有用的。

The key transition described in this diagram is the decomposition of single-phase austenite(γ)to the two-phase ferrite plus carbide structure as temperature drops.在此圖中描述的關(guān)鍵轉(zhuǎn)變是單相奧氏體(γ)隨著溫度下降分解成兩相鐵素體加滲碳體組織結(jié)構(gòu)。

Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制這一由于奧氏體和鐵素體的碳溶解性完全不同而產(chǎn)生的反應(yīng)，使得通過(guò)熱處理能獲得很大范圍的特性。To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in Fig.2.1.At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron.When the steel cools to 727℃(1341℉), several changes occur simultaneously.為了理解這些過(guò)程，考慮含碳量為0.77%的共析鋼，沿著圖2.1的x-x’線慢慢冷卻。在較高溫度時(shí)，只存在奧氏體，0.77%的碳溶解在鐵里形成固溶體。當(dāng)鋼冷卻到727℃(1341℉)時(shí)，將同時(shí)發(fā)生若干變化。

The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution.鐵需要從面心立方體奧氏體結(jié)構(gòu)轉(zhuǎn)變?yōu)轶w心立方體鐵素體結(jié)構(gòu)，但是鐵素體只能容納固溶體狀態(tài)的0.02%的碳。The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C.In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.被析出的碳與金屬化合物Fe3C形成富碳的滲碳體。本質(zhì)上，共析體的基本反應(yīng)是奧氏體0.77%的碳→鐵素體0.02%的碳+滲碳體6.67%的碳。

Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite.Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.由于這種碳成分的化學(xué)分離完全發(fā)生在固態(tài)中，產(chǎn)生的組織結(jié)構(gòu)是一種細(xì)致的鐵素體與滲碳體的機(jī)械混合物。通過(guò)打磨并在弱硝酸酒精溶液中蝕刻制備的樣本顯示出由緩慢冷卻形成的交互層狀的薄片結(jié)構(gòu)。

This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother-of-pearl at low magnification.這種結(jié)構(gòu)由兩種截然不同的狀態(tài)組成，但它本身具有一系列特性，且因與低倍數(shù)放大時(shí)的珠母層有類同之處而被稱為珠光體。

Steels having less than the eutectoid amount of carbon(less than 0.77%)are known as hypo-eutectoid steels.Consider now the transformation of such a material represented by cooling along line y-y’ in Fig.2.1.含碳量少于共析體(低于0.77%)的鋼稱為亞共析鋼?，F(xiàn)在來(lái)看這種材料沿著圖2.1中y-y’ 線冷卻的轉(zhuǎn)變情況。At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite.Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.在較高溫度時(shí)，這種材料全部是奧氏體，但隨著冷卻就進(jìn)入到鐵素體和奧氏體穩(wěn)定狀態(tài)的區(qū)域。由截線及杠桿定律分析可知，低碳鐵素體成核并長(zhǎng)大，剩下含碳量高的奧氏體。

At 727℃(1341℉), the austenite is of eutectoid composition(0.77% carbon)and further cooling transforms the remaining austenite to pearlite.The resulting structure is a mixture of primary or pro-eutectoid ferrite(ferrite that formed above the eutectoid reaction)and regions of pearlite.在727℃(1341℉)時(shí)，奧氏體為共析組成(含碳量0.77%)，再冷卻剩余的奧氏體就轉(zhuǎn)化為珠光體。作為結(jié)果的組織結(jié)構(gòu)是初步的共析鐵素體(在共析反應(yīng)前的鐵素體)和部分珠光體的混合物。

Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon.When such steel cools, as shown in z-z’ of Fig.2.1 the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite.過(guò)共析鋼是含碳量大于共析量的鋼。當(dāng)這種鋼冷卻時(shí)，就像圖2.1的z-z’線所示，除了初步的共析狀態(tài)用滲碳體取代鐵素體外，其余類似亞共析鋼的情況。

As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉).As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature.隨著富碳部分的形成，剩余奧氏體含碳量減少，在727℃(1341℉)時(shí)達(dá)到共析組織。就像以前說(shuō)的一樣，當(dāng)緩慢冷卻到這溫度時(shí)所有剩余奧氏體轉(zhuǎn)化為珠光體。

It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated by slow cooling.With slow heating, these transitions occur in the reverse manner.應(yīng)該記住由狀態(tài)圖描述的這種轉(zhuǎn)化只適合于通過(guò)緩慢冷卻的近似平衡條件。如果緩慢加熱，則以相反的方式發(fā)生這種轉(zhuǎn)化。

However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis.然而，當(dāng)快速冷卻合金時(shí)，可能得到完全不同的結(jié)果。因?yàn)闆](méi)有足夠的時(shí)間讓正常的狀態(tài)反應(yīng)發(fā)生，在這種情況下對(duì)工程分析而言狀態(tài)圖不再是有用的工具。

? Hardening

淬火

Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.淬火就是把鋼件加熱到或超過(guò)它的臨界溫度范圍，然后使其快速冷卻的過(guò)程。

If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram.However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range.如果鋼的含碳量已知，鋼件合適的加熱溫度可參考鐵碳合金狀態(tài)圖得到。然而當(dāng)鋼的成分不知道時(shí)，則需做一些預(yù)備試驗(yàn)來(lái)確定其溫度范圍。

A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination.When the correct temperature is obtained, there will be a marked change in hardness and other properties.要遵循的合適步驟是將這種鋼的一些小試件加熱到不同的溫度后淬火，再通過(guò)硬度試驗(yàn)或顯微鏡檢查觀測(cè)結(jié)果。一旦獲得正確的溫度，硬度和其它性能都將有明顯的變化。

In any heat-treating operation the rate of heating is important.Heat flows from the exterior to the interior of steel at a definite rate.If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained.在任何熱處理作業(yè)中，加熱的速率都是重要的。熱量以一定的速率從鋼的外部傳導(dǎo)到內(nèi)部。如果鋼被加熱得太快，其外部比內(nèi)部熱就不能得到均勻的組織結(jié)構(gòu)。

If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking.The heavier the section, the longer must be the heating time to achieve uniform results.如果工件形狀不規(guī)則，為了消除翹曲和開(kāi)裂最根本的是加熱速率要緩慢。截面越厚，加熱的時(shí)間就要越長(zhǎng)才能達(dá)到均勻的結(jié)果。

Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.即使加熱到正確的溫度后，工件也應(yīng)在此溫度下保持足夠時(shí)間以讓其最厚截面達(dá)到相同溫度。

The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size.In alloy steels the kind and amount of alloying element influences only the hardenability(the ability of the workpiece to be hardened to depths)of the steel and does not affect the hardness except in unhardened or partially hardened steels.通過(guò)給定的熱處理所得到的硬度取決于淬火速率、含碳量和工件尺寸。除了非淬硬鋼或部分淬硬鋼外，合金鋼中合金元素的種類及含量?jī)H影響鋼的淬透性(工件被硬化到深層的能力)而不影響硬度。

Steel with low carbon content will not respond appreciably to hardening treatment.As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases.含碳量低的鋼對(duì)淬火處理沒(méi)有明顯的反應(yīng)。隨著鋼的含碳量增加到大約0.60%，可能得到的硬度也增加。Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state.Pearlite responds best to heat-treating operations;and steel composed mostly of pearlite can be transformed into a hard steel.高于此點(diǎn)，由于超過(guò)共析點(diǎn)鋼完全由珠光體和退火狀態(tài)的滲碳體組成，硬度增加并不多。珠光體對(duì)熱處理作業(yè)響應(yīng)最好；基本由珠光體組成的鋼能轉(zhuǎn)化成硬質(zhì)鋼。

As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same.There is a limit to the rate of heat flow through steel.即使所有其它條件保持不變，隨著要淬火的零件尺寸的增加其表面硬度也會(huì)有所下降。熱量在鋼中的傳導(dǎo)速率是有限的。

No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness.However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature.無(wú)論淬火介質(zhì)怎么冷，如果在大工件中的熱量不能比特定的臨界速率更快散發(fā)，那它內(nèi)部硬度就會(huì)受到明確限制。然而鹽水或水淬火能夠?qū)⒈淮懔慵谋砻嫜杆倮鋮s至本身溫度并將其保持或接近此溫度。

Under these circumstances there would always be some finite depth of surface hardening regardless of size.This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.在這種情況下不管零件尺寸如何，其表面總歸有一定深度被硬化。但油淬情況就不是如此，因?yàn)橛痛銜r(shí)在淬火臨界階段零件表面的溫度可能仍然很高。

? Tempering

回火

Steel that has been hardened by rapid quenching is brittle and not suitable for most uses.By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions．

快速淬火硬化的鋼是硬而易碎的，不適合大多數(shù)場(chǎng)合使用。通過(guò)回火，硬度和脆性可以降低到使用條件所需要的程度。

As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel.The operation consists of reheating quench-hardened steel to some temperature below the critical range followed by any rate of cooling.隨著這些性能的降低，拉伸強(qiáng)度也降低而鋼的延展性和韌性則會(huì)提高?；鼗鹱鳂I(yè)包括將淬硬鋼重新加熱到低于臨界范圍的某一溫度然后以任意速率冷卻。

Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would.The final structure obtained from tempering a fully hardened steel is called tempered martensite.雖然這過(guò)程使鋼軟化，但它與退火是大不相同的，因?yàn)榛鼗疬m合于嚴(yán)格控制物理性能并在大多數(shù)情況下不會(huì)把鋼軟化到退火那種程度?；鼗鹜耆阌蹭摰玫降淖罱K組織結(jié)構(gòu)被稱為回火馬氏體。

Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel.Low-temperature draws, from 300℉ to 400℉(150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains.由于馬氏體這一淬硬鋼主要成分的不穩(wěn)定性，使得回火成為可能。低溫回火，300℉到400℉(150℃~205℃)，不會(huì)引起硬度下降很多，主要用于減少內(nèi)部應(yīng)變。

As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃)the change to a structure called tempered martensite is very rapid.The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite.隨著回火溫度的提高，馬氏體以較快的速率分解，并在大約600℉(315℃)迅速轉(zhuǎn)變?yōu)楸环Q為回火馬氏體的結(jié)構(gòu)?；鼗鹱鳂I(yè)可以描述為滲碳體析出和凝聚或聚結(jié)的過(guò)程。

A substantial precipitation of cementite begins at 600℉(315℃), which produces a decrease in hardness.Increasing the temperature causes coalescence of the carbides with continued decrease in hardness.滲碳體的大量析出開(kāi)始于600℉(315℃)，這使硬度下降。溫度的上升會(huì)使碳化物聚結(jié)而硬度繼續(xù)降低。In the process of tempering, some consideration should be given to time as well as to temperature.Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.在回火過(guò)程中，不但要考慮溫度而且要考慮時(shí)間。雖然大多數(shù)軟化作用發(fā)生在達(dá)到所需溫度后的最初幾分鐘，但如果此溫度維持一段延長(zhǎng)時(shí)間，仍會(huì)有些額外的硬度下降。

Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated.通常的做法是將鋼加熱到所需溫度并且僅保溫到正好使其均勻受熱。

Two special processes using interrupted quenching are a form of tempering.In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool.These processes, known as austempering and martempering, result in products having certain desirable physical properties.兩種采用中斷淬火的特殊工藝也是回火的形式。這兩種工藝中，淬硬鋼在其被允許冷卻前先在一選定的較低溫度鹽浴淬火。這兩種分別被稱為奧氏體回火和馬氏體回火的工藝，能使產(chǎn)品具有特定所需的物理性能。

? Annealing

退火

The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.退火的主要目的是使堅(jiān)硬的鋼軟化以便機(jī)加工或冷作。

This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same.通常是非常緩慢地將鋼加熱到臨界溫度以上，并將其在此溫度下保持到工件全部均勻受熱，然后以受控的速率慢慢地冷卻，這樣使得工件表面和內(nèi)部的溫度近似相同。

This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal.Annealing also relieves internal stresses previously set up in the metal.這過(guò)程被稱為完全退火，因?yàn)樗コ艘郧敖M織結(jié)構(gòu)的所有痕跡、細(xì)化晶粒并軟化金屬。退火也釋放了先前在金屬中的內(nèi)應(yīng)力。

The temperature to which a given steel should be heated in annealing depends on its composition;for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram.When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.給定的鋼其退火溫度取決于它的成分；對(duì)碳鋼而言可容易地從局部的鐵碳合金平衡圖得到。達(dá)到退火溫度后，鋼應(yīng)當(dāng)保持在此溫度等到全部均勻受熱。

This usually takes about 45min for each inch(25mm)of thickness of the largest section.For maximum softness and ductility the cooling rate should be very slow, such as allowing the parts to cool down with the furnace.The higher the carbon content, the slower this rate must be.加熱時(shí)間一般以工件的最大截面厚度計(jì)每英寸(25mm)大約需45min。為了得到最大柔軟性和延展性冷卻速率應(yīng)該很慢，比如讓零件與爐子一起冷下來(lái)。含碳量越高，冷卻的速率必須越慢。

The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible.加熱的速率也應(yīng)與截面的尺寸及均勻程度相協(xié)調(diào)，這樣才能使整個(gè)零件盡可能均勻地加熱。

? Normalizing and Spheroidizing 正火和球化

The process of normalizing consists of heating the steel about 50℉ to 100℉

(10℃~40℃)above the upper critical range and cooling in still air to room temperature.正火處理包括先將鋼加熱到高于上臨界區(qū)50℉到100℉(10℃~40℃)然后在靜止的空氣中冷卻到室溫。This process is principally used with low-and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties.Most commercial steels are normalized after being rolled or cast.退火主要用于低碳鋼、中碳鋼及合金鋼，使晶粒結(jié)構(gòu)更均勻、釋放內(nèi)應(yīng)力或獲得所需的物理特性。大多數(shù)商業(yè)鋼材在軋制或鑄造后都要退火。

Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution.If steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time, this structure will be obtained.球化是使?jié)B碳體產(chǎn)生成類似球狀分布結(jié)構(gòu)的工藝。如果把鋼緩慢加熱到恰好低于臨界溫度并且保持較長(zhǎng)一段時(shí)間，就能得到這種組織結(jié)構(gòu)。

The globular structure obtained gives improved machinability to the steel.This treatment is particularly useful for hypereutectoid steels that must be machined.所獲得的球狀結(jié)構(gòu)改善了鋼的可切削性。此處理方法對(duì)必須機(jī)加工的過(guò)共析鋼特別有用。

? Surface Hardening 表面硬化 Carburizing The oldest known method of producing a hard surface on steel is case hardening or carburizing.Iron at temperatures close to and above its critical temperature has an affinity for carbon.滲碳

最早的硬化鋼表面的方法是表面淬火或滲碳。鐵在靠近并高于其臨界溫度時(shí)對(duì)碳具有親合力。

The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel.The carbon is gradually diffused to the interior of the part.The depth of the case depends on the time and temperature of the treatment.碳被吸收進(jìn)金屬與鐵形成固溶體使外表面轉(zhuǎn)變成高碳鋼。碳逐漸擴(kuò)散到零件內(nèi)部。滲碳層的深度取決于熱處理的時(shí)間和溫度。

Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke.It is a long process and used to produce fairly thick cases of from 0.03 to 0.16 in.(0.76~4.06mm)in depth.固體滲碳的方法是將要處理的零件與木炭或焦炭這些含碳的材料一起放入密閉容器。這是一個(gè)較長(zhǎng)的過(guò)程，用于產(chǎn)生深度為0.03到0.16 英寸(0.76~4.06mm)這么厚的硬化層。

Steel for carburizing is usually a low-carbon steel of about 0.15% carbon that would not in itself responds appreciably to heat treatment.In the course of the process the outer layer is converted into high-carbon steel with a content ranging from 0.9% to 1.2% carbon.用于滲碳的一般是含碳量約為0.15%、本身不太適合熱處理的低碳鋼。在處理過(guò)程中外層轉(zhuǎn)化為含碳量從0.9%到1.2%的高碳鋼。

A steel with varying carbon content and, consequently, different critical temperatures requires a special heat treatment.含碳量變化的鋼具有不同的臨界溫度，因此需要特殊的熱處理。

Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then cooled, thus refining the core structure.The steel should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine structure.由于在較長(zhǎng)的滲碳過(guò)程中鋼內(nèi)部會(huì)有些晶粒生長(zhǎng)，所以工件應(yīng)該加熱到核心部分的臨界溫度再冷卻以細(xì)化核心部分的組織結(jié)構(gòu)。然后重新加熱到高于外層轉(zhuǎn)變溫度再淬火以生成堅(jiān)硬、細(xì)致的組織結(jié)構(gòu)。

The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point.A third tempering treatment may be used to reduce strains.由于恰好高于低臨界溫度通常使過(guò)共析鋼奧氏體化而硬化，所以對(duì)外層采用較低的熱處理溫度。第三次回火處理可用于減少應(yīng)變。

Carbonitriding Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共滲

碳氮共滲，有時(shí)也稱為干法氰化或滲碳氮化，是一種表面硬化工藝。通過(guò)把鋼放在高于臨界溫度的氣體中，讓它吸收碳和氮。

Any carbon-rich gas with ammonia can be used.The wear-resistant case produced ranges from 0.003 to 0.030 inch(0.08~ 0.76mm)in thickness.An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels.可以使用任何富碳?xì)怏w加氨氣，能生成厚度從0.003到0.030英寸(0.08~ 0.76mm)的耐磨外層。碳氮共滲的優(yōu)點(diǎn)之一是加入氮后外層的淬透性極大增加，為使用低價(jià)鋼提供條件。

Cyaniding Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化

氰化，有時(shí)稱為液體碳氮共滲，也是一種結(jié)合了吸收碳和氮來(lái)獲得表面硬度的工藝，它主要用于不適合通常熱處理的低碳鋼。

The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case.The part is then quenched in water or oil to obtain a hard surface.需表面硬化的零件浸沒(méi)在略高于Ac1溫度熔化的氰化鈉鹽溶液中，浸泡的持續(xù)時(shí)間取決于硬化層的深度。然后將零件在水或油中淬火。

Case depths of 0.005 to 0.015in.(0.13~0.38mm)may be readily obtained by this process.Cyaniding is used principally for the treatment of small parts.通過(guò)這樣處理可以容易地獲得0.005到0.015英寸(0.13~0.38mm)的硬化深度。氰化主要用于處理小零件。Nitriding Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents.滲氮

滲氮有些類似普通表面硬化，但它采用不同的材料和處理方法來(lái)產(chǎn)生堅(jiān)硬表面成分。

In this process the metal is heated to a temperature of around 950℉(510℃)and held there for a period of time in contact with ammonia gas.Nitrogen from the gas is introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal.這種工藝中金屬加熱到約950℉(510℃)，然后與氨氣接觸一段時(shí)間。氨氣中的氮進(jìn)入鋼內(nèi)，形成細(xì)微分布于金屬表面又十分堅(jiān)固的氮化物。

Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed.氮與某些元素的硬化能力比其它元素大，因此開(kāi)發(fā)了專用的滲氮合金鋼。

Aluminum in the range of 1% to 1.5% has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent.The temperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).在鋼中含鋁1%到1.5%被證明特別合適，它能與氨氣結(jié)合形成很穩(wěn)定堅(jiān)固的成分。其加熱溫度范圍為925℉到1,050℉(495℃~565℃)。

Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range.Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths.液體滲氮利用熔化的氰化物鹽，就像氣體滲氮，溫度保持在低于轉(zhuǎn)化范圍內(nèi)。液體滲氮時(shí)在氰化物溶液中加入比氰化及滲碳都較多的氮和較少的碳。

Case thickness of 0.001 to 0.012in.(0.03~0.30mm)is obtained, whereas for gas nitriding the case may be as thick as 0.025 in.(0.64mm).In general the uses of the two-nitriding processes are similar.液體滲氮可以獲得厚度為0.001到0.012英寸(0.03~0.30mm)的硬化層，然而氣體滲氮?jiǎng)t能獲得厚0.025英寸(0.64mm)的硬化層。一般而言兩種滲氮方法的用途是類似的。

Nitriding develops extreme hardness in the surface of steel.This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening.滲氮在鋼表面獲得遠(yuǎn)遠(yuǎn)超出正常標(biāo)準(zhǔn)的硬度。其硬度范圍為900到1,100布氏硬度，這遠(yuǎn)高于普通表面硬化所獲得的硬度。

Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment.It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process.由于滲氮鋼的合金比例，它們比普通鋼更強(qiáng)，也容易熱處理。建議對(duì)這種鋼在滲氮前先機(jī)加工和熱處理，因?yàn)闈B氮后沒(méi)有剝落并不需要更多的加工。

Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is little tendency to warp, develop cracks, or change condition in any way.The surface

effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.值得慶幸的是由于滲氮處理一點(diǎn)都不影響內(nèi)部結(jié)構(gòu)和性能，也無(wú)需淬火，所以幾乎沒(méi)有任何產(chǎn)生翹曲、裂縫及變化條件的趨勢(shì)。這種表面能有效地抵御水、鹽霧、堿、原油和天然氣的腐蝕反應(yīng)。

第三單元

Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity.During or after cooling, the cast part is removed from the mold and then processed for delivery.鑄造是一種將熔化的金屬倒入或注入合適的鑄模腔并且在其中固化的制造工藝。在冷卻期間或冷卻后，把鑄件從鑄模中取出，然后進(jìn)行交付。

Casting processes and cast-material technologies vary from simple to highly complex.Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level.鑄造工藝和鑄造材料技術(shù)從簡(jiǎn)單到高度復(fù)雜變化很大。材料和工藝的選擇取決于零件的復(fù)雜性和功能、產(chǎn)品的質(zhì)量要求以及成本預(yù)算水平。

Castings are parts that are made close to their final dimensions by a casting process.With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made.通過(guò)鑄造加工，鑄件可以做成很接近它們的最終尺寸?；厮?,000年歷史，各種各樣的鑄造工藝就如同科技進(jìn)步一樣處于一個(gè)不斷改進(jìn)和發(fā)展的狀態(tài)。

? Sand Casting

砂型鑄造

Sand casting is used to make large parts(typically iron, but also bronze, brass, aluminum).Molten metal is poured into a mold cavity formed out of sand(natural or synthetic).砂型鑄造用于制造大型零件(具有代表性是鐵，除此之外還有青銅、黃銅和鋁)。將熔化的金屬倒入由型砂(天然的或人造的)做成鑄模腔。

The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance.本節(jié)討論砂型鑄造工藝，包括型模、澆注口、澆道、設(shè)計(jì)考慮因素及鑄造余量。

The cavity in the sand is formed by using a pattern(an approximate duplicate of the real part), which are typically made out of wood, sometimes metal.The cavity is contained in an aggregate housed in a box called the flask.砂型里的型腔是采用型模(真實(shí)零件的近似復(fù)制品)構(gòu)成的，型模一般為木制，有時(shí)也用金屬制造。型腔整個(gè)包含在一個(gè)被放入稱為砂箱的箱子里的組合體內(nèi)。

Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages.Cores are placed in the cavity to form holes of the desired shapes.Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold.砂芯是插入鑄模的砂型，用于生成諸如孔或內(nèi)通道之類的內(nèi)部特征。砂芯安放在型腔里形成所需形狀的孔洞。砂芯座是加在型模、砂芯或鑄模上的特定區(qū)域，用來(lái)在鑄模內(nèi)部定位和支撐砂芯。

A riser is an extra void created in the mold to contain excessive molten material.The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.冒口是在鑄模內(nèi)部增加的額外空間，用于容納過(guò)多的熔化金屬。其目的是當(dāng)熔化金屬凝固和收縮時(shí)往型腔里補(bǔ)充熔化金屬，從而防止在主鑄件中產(chǎn)生孔隙。

In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1.The parting line or the parting surface is line or surface that separates the cope and drag.在典型砂型鑄造的兩箱鑄模中，上半部分(包括型模頂半部、砂箱和砂芯)稱為上型箱，下半部分稱為下型箱，見(jiàn)圖3.1所示。分型線或分型面是分離上下型箱的線或面。

The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line.The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system.首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型線處放置澆注系統(tǒng)。然后將上型箱與下型箱裝配在一起，再把型砂倒入上型箱蓋住型模、砂芯和澆注系統(tǒng)。

The sand is compacted by vibration and mechanical means.Next, the cope is removed from the drag, and the pattern is carefully removed.The object is to remove the pattern without breaking the mold cavity.型砂通過(guò)振動(dòng)和機(jī)械方法壓實(shí)。然后從下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破壞型腔。

This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern.This is usually a minimum of 1.5mm(0.060in.), whichever is greater.The rougher the surface of the pattern, the more the draft to be provided.通過(guò)設(shè)計(jì)拔模斜度—型模垂直相交表面的微小角度偏移量—來(lái)使取出型模變得容易。拔模斜度最小一般為1.5mm(0.060in.)，只能比此大。型模表面越粗糙，則拔模斜度應(yīng)越大。

The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity.熔化的金屬?gòu)臐沧⒈⑷胄颓?，澆注杯是澆注系統(tǒng)向型腔提供熔化金屬的部分。

The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.將澆注系統(tǒng)的垂直部分與澆注杯連接的是澆注口，澆注系統(tǒng)的水平部分稱為澆道，最后到多點(diǎn)把熔化金屬導(dǎo)入型腔的稱為閘道。

Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere.除此之外，還有稱為排放口的澆注系統(tǒng)延長(zhǎng)段，它為合成氣體和置換空氣排放到大氣提供通道。

The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature.This is achieved by making the pattern oversize.To account for shrinking, the pattern must be made oversize by these factors on the average.These are linear factors and apply in each direction.型腔通常大于所需尺寸以允許在金屬冷卻到室溫時(shí)收縮。這通過(guò)把型模做得大于所需尺寸來(lái)達(dá)到。為解決收縮效應(yīng)，一般而言型模做得比所需尺寸大，必須考慮線性因素并作用于各個(gè)方向。

These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting.In addition, different parts of the casting might require different shrinkage allowances.收縮余量?jī)H僅是近似的，因?yàn)闇?zhǔn)確的余量是由鑄件的形狀和尺寸決定的。另外，鑄件的不同部分也可能需要不同的收縮余量。

Sand castings generally have a rough surface sometimes with surface impurities, and surface variations.A machining(finish)allowance is made for this type of defect.砂型鑄件一般表面粗糙，有時(shí)還帶有表面雜質(zhì)和表面變異。對(duì)這類缺陷采用機(jī)加工(最后一道工序)的余量。In general, typical stages of sand casting operation include(as shown in Fig.3.2): 1.Patterns are made.These will be the shape used to form the cavity in the sand.一般而言，砂型鑄造作業(yè)的典型階段包括(如圖3.2所示)： 1.制作型模。做成用于在型砂中形成型腔的形狀。

2.Cores may also be made at this time.These cores are made of bonded sand that will be broken out of the cast part after it is complete.3.Sand is mulled(mixed)thoroughly with additives such as bentonite to increase bonding and overall strength.2.同時(shí)還要制作砂芯。這些砂芯用粘結(jié)砂做成，等鑄件完成后將被打碎取出。3.型砂與膨潤(rùn)土之類的添加劑充分地混合以增強(qiáng)連接及整體強(qiáng)度。

4.Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed.A

compaction stage is typically used to ensure good coverage and solid molds.4.型砂在型模周?chē)尚?，并根?jù)需要安放閘道、澆道、冒口、排放口和澆注杯等。通常要采取壓緊步驟來(lái)保證良好的覆蓋和堅(jiān)固的鑄型。

Cores may also be added to make concave or internal features for the cast part.Alignment pins may also be used for mating the molds later.Chills may be added to cool large masses faster.安放砂芯來(lái)制成鑄件的凹形結(jié)構(gòu)或內(nèi)部特征。為了以后鑄模匹配還要用到定位銷(xiāo)。對(duì)大質(zhì)量鑄件可能需要加入冷卻物來(lái)使其較快冷卻。

5.The patterns are removed, and the molds may be put through a baking stage to increase strength.6.Mold halves are mated and prepared for pouring metal.5.取走型模，將鑄模烘焙以增加強(qiáng)度。6.匹配上下鑄模，做好澆鑄金屬的準(zhǔn)備。

7.Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range(we don’t want the metal solidifying before the pour is complete).The exact temperature may be closely controlled depending upon the application.7.金屬在熔爐或坩堝中預(yù)熱到高于液化溫度的一個(gè)合適范圍內(nèi)(不希望金屬在澆鑄完成前凝固)。確切的溫度要根據(jù)應(yīng)用場(chǎng)合嚴(yán)格控制。

Degassing, and other treatment processes may be done at this time, such as removal of impurities(i.e.slag).Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable.在此期間還要進(jìn)行排氣和其它處理步驟，例如去除雜質(zhì)(即熔渣)?？梢约尤胍欢吭仁沁@種金屬鑄件的廢料再融化—10%是適當(dāng)?shù)摹?/p>

8.The metal is poured slowly, but continuously into the mold until the mold is full.9.As the molten metal cools(minutes to days), the metal will shrink and the volume will decrease.During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape.8.將金屬緩慢而連續(xù)地注滿型模。

9.隨著熔化金屬的冷卻(幾分鐘到幾天)，金屬收縮體積減小。在此期間熔化金屬可能從冒口回流供給零件以保持其形狀不變。

10.Once the part starts to solidify small dendrites of solid material form in the part.During this time metal properties are being determined, and internal stresses are being generated.If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.10.在零件開(kāi)始凝固其內(nèi)部形成固態(tài)金屬的小型樹(shù)枝狀結(jié)晶期間金屬性能被確定，同時(shí)也產(chǎn)生了內(nèi)應(yīng)力。如果零件以恒定速率冷卻得足夠緩慢，最終零件將相對(duì)均質(zhì)并釋放內(nèi)應(yīng)力。

11.Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal

properties.At this point the sand is simply broken up, and the part removed.At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.11.一旦零件在共析點(diǎn)以下完全凝固，可以不考慮金屬的最后性能而將其取出。這時(shí)可以簡(jiǎn)單地打碎砂型并取出零件，但零件表面會(huì)有大量型砂粘附著，內(nèi)部還有實(shí)心的砂芯。

12.A bulk of the remaining sand and cores can be removed by mechanically striking the part.Other options are to use a vibrating table, sand/shot blaster, hand labor, etc.12.大量的剩余型砂和砂芯要通過(guò)機(jī)械敲擊零件來(lái)去除。其它的選擇還有采用振動(dòng)臺(tái)、噴砂/噴丸機(jī)、手工作業(yè)等等。

13.The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc.Grinding operations are used to remove any remaining bulk.14.The part is taken down to final shape using machining operations.And cleaning operations may be used to remove oxides, etc.13.最后零件要用刀具、噴槍等切掉澆道閘道系統(tǒng)，這樣就接近最終形狀了。再用磨削作業(yè)去除多余的部分。14.通過(guò)機(jī)加工將零件切削到最終形狀?？赡苓€要用清洗作業(yè)去除氧化物等。

? Investment casting 熔模鑄造

Investment casting is also known as the lost wax process.This process is one of the oldest manufacturing processes.The Egyptians used it in the time of the Pharaohs to make gold jewelry(hence the name Investment)some 5,000 years ago.熔模鑄造也稱為失蠟加工。這是最古老的制造工藝之一。大約在5,000年前的法老王時(shí)代，埃及人就用它制造黃金飾品(因此而得名投資)。

Intricate shapes can be made with high accuracy.In addition, metals that are hard to machine or fabricate are good candidates for this process.It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures.復(fù)雜的形狀能被高精度地制造。另外較難機(jī)加工或制作的金屬都能用此工藝。它還能用于生產(chǎn)一般制造技術(shù)無(wú)法生產(chǎn)的零件，例如有復(fù)雜形狀的渦輪葉片或必須耐得住高溫的飛機(jī)零件。

The mold is made by making a pattern using wax or some other material that can be melted away.This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin.This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.制作鑄型的型模采用石蠟或其它一些能被融化掉的材料做成。石蠟型模浸泡在耐熱漿里，讓它覆蓋型模并形成外殼，然后使其變干。重復(fù)這個(gè)浸泡、變干的過(guò)程直至獲得足夠的厚度。

After this, the entire pattern is placed in an oven and the wax is melted away.This leads to a mold that can be filled with the molten metal.Because the mold is formed around a one-piece pattern(which does not have to be pulled out from

the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.完成后把整個(gè)型模放在烤箱里融化石蠟。這樣就做成了能填充熔化金屬的鑄型。由于這種鑄型是環(huán)繞整塊型模形成的(無(wú)需像傳統(tǒng)的砂型鑄造工藝那樣拔模)，能制作十分復(fù)雜的零件和浮雕。

The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master.石蠟型模本身能用立體制版或類似的模型復(fù)制—這可以采用計(jì)算機(jī)立體模型原版制作。

The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts.For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder.對(duì)較低熔化溫度而言，用于耐熱漿的材料是石膏作粘合劑和用粉末狀硅石作耐溫材料的混合物。對(duì)較高熔化溫度而言，則采用硅線石或氧化鋁硅酸鹽作耐溫材料、無(wú)水硅酸作粘合劑。

Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied.The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry.根據(jù)最后所需光潔度也可采用硅線石和乙烷基硅酸鹽。這樣生成的鑄?？芍苯佑糜诒”阼T件或通過(guò)將其放在較大容器內(nèi)用更多耐熱漿加強(qiáng)。

Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉)to remove any residues of wax, harden the binder.The pour in the pre-heated mold also ensures that the mold will fill completely.在正要澆鑄之前，將型模預(yù)熱到約1,000℃(1,832℉)以去除剩余石蠟、硬化粘合劑。在預(yù)熱的型模中澆鑄也能保證型模完全充滿。

Pouring can be done using gravity, pressure or vacuum conditions.Attention must be paid to mold permeability when using pressure, to allow the air to escape as the pour is done.澆鑄可采用重力、壓力或真空條件來(lái)實(shí)現(xiàn)。當(dāng)使用壓力時(shí)必須注意滲透性，以便在澆鑄的同時(shí)讓空氣逸出。Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions.Castings can weigh from a few grams to 35kg(0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb).Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.)for alloys that can be cast easily.一般公差可能為長(zhǎng)度的0.5%，小尺寸可能低到0.15%。雖然通常尺寸的鑄件重量范圍為200g到約8kg(7oz到15lb)，但實(shí)際可從幾克到35kg(0.1oz to 80lb)。對(duì)容易鑄造的合金而言，通常壁厚約為1mm到0.5mm(0.040~ 0.020 in.)。

The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, stellite, hastelloys, and precious metals.Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.可以用于鑄造的材料類型有：鋁合金、青銅、工具鋼、不銹鋼、鎢鉻鈷合金、鎳基合金和貴金屬。采用熔模鑄造的零件常常不需要進(jìn)一步加工，因?yàn)槿勰ｈT造能達(dá)到精密的公差。

? Centrifugal Casting 離心鑄造

Centrifugal casting(Fig.3.3)as a category includes centrifugal casting, semi-centrifugal casting and centrifuging.In centrifugal casting, a permanent mold is rotated about its axis at high speeds(300 to 3,000rpm)as the molten metal is poured.離心鑄造(圖3.3)作為一個(gè)種類包括了離心鑄造、半離心鑄造和離心法鑄造。離心鑄造中，永久性的型模在熔化金屬澆鑄時(shí)以較高速度(300到3,000rpm)繞其軸線旋轉(zhuǎn)。

The molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling.The casting is usually a fine grain casting with a very fine-grained outer diameter, which is resistant to atmospheric corrosion, a typical situation with pipes.The inside diameter has more impurities and inclusions, which can be machined away.受離心力作用熔化金屬被拋向型模的內(nèi)壁，在那里冷卻后固化。這種鑄件通常為外徑處晶粒非常細(xì)小的細(xì)晶粒鑄件，能耐大氣腐蝕，典型的情況是管子。內(nèi)徑處則有較多的雜質(zhì)和內(nèi)含物，但可用機(jī)加工去除。

Only cylindrical shapes can be produced with this process.Size limits are up to 3m(10feet)diameter and 15m(50 feet)length.Wall thickness can be 2.5mm to 125mm(0.1~5.0in.).The tolerances that can be held on the OD can be as good as 2.5mm(0.1in.)and on the ID can be 3.8mm(0.15in.).The surface finish ranges from 2.5mm to 12.5mm(0.1~0.5in.)rms(root-mean-square).只有圓柱形才能用此工藝生產(chǎn)。尺寸限制為直徑大到3m(10feet)、長(zhǎng)度大到15m(50feet)。壁厚為2.5mm到125mm(0.1~5.0in.)。外徑公差保持在2.5mm(0.1in.)以內(nèi)，內(nèi)徑公差保持在3.8mm(0.15in.)以內(nèi)。表面粗糙度的有效值(均方根)范圍為2.5mm到12.5mm(0.1~0.5in.)。

Typical materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel.Two materials can be cast by introducing a second material during the process.Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axis-symmetric.可用此工藝鑄造的典型材料有：鐵、鋼、不銹鋼以及鋁、銅和鎳的合金。通過(guò)在生產(chǎn)過(guò)程中加入第二種材料能進(jìn)行兩種材料鑄造。采用這種工藝制造的典型零件有：管子、鍋爐、壓力容器、飛輪、汽缸襯墊和其它軸對(duì)稱零件。

Semi-centrifugal casting.The molds used can be permanent or expendable, can be stacked as necessary.The rotational speeds are lower than those used in centrifugal casting.半離心鑄造：型?？梢允怯谰眯缘幕蚴窍男缘?，可根據(jù)需要疊加。它的旋轉(zhuǎn)速度比離心鑄造低。

The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away.This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.零件的中心軸附近存在缺陷和孔隙，因此僅適用于能將這些機(jī)加工去除的零件。這種工藝被用于制造車(chē)輪、管嘴及類似的隨后可用機(jī)加工去除中心軸部分的零件。

Centrifuging.Centrifuging is used for forcing metal from a central axis of the equipment into individual mold cavities that are placed on the circumference.This provides a means of increasing the filling pressure within each mold and allows for reproduction of intricate details.This method is often used for the pouring of investment casting pattern.離心法鑄造：離心法鑄造用于迫使金屬?gòu)脑O(shè)備的中心軸進(jìn)入分布在圓周上的單獨(dú)型腔。它為每個(gè)型腔提供了一種增加填充壓力方法并允許再現(xiàn)復(fù)雜細(xì)節(jié)。這種方法常用于澆鑄熔模鑄型。

Full-mold casting is a technique similar to investment casting, but instead of wax as the expendable material, polystyrene foam is used as the pattern.The foam pattern is coated with a refractory material.The pattern is encased in a one-piece sand mold.As the metal is poured, the foam vaporizes, and the metal takes its place.實(shí)型鑄造是與熔模鑄造類似的技術(shù)，但它用做型模的消耗材料是聚苯乙烯泡沫而不是石蠟。泡沫型模用難熔材料覆蓋。型模裝入整體砂模中。當(dāng)金屬澆入時(shí)，泡沫材料蒸發(fā)，金屬取代其位置。

This can make complex shaped castings without any draft or flash.However, the pattern cost can be high due to the expendable nature of the pattern.Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions.Surface finish can be held from 2.5μm to 25μm(0.1μin.to 1.0μin.)rms(root-mean-square).它能制造沒(méi)有拔模斜度和縫脊的復(fù)雜形狀鑄件。然而由于型模的消耗特性，型模成本可能較高。最小壁厚為2.5mm，公差能保持在尺寸的0.3% 之內(nèi)。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之間。

Size limits are from 400g(1lb)to several tons.No draft allowance is required.Typical materials that can be cast with this process are aluminum, iron, steel, nickel alloys, copper alloys.Types of parts that can be made using these processes are pump housings, manifolds, and auto brake components.重量限制從400g(1lb)到數(shù)噸。無(wú)需留拔模余量。這種工藝所用的典型材料有：鋁、鐵、鋼、鎳合金、銅合金?？梢圆捎眠@些工藝制造的零件類型有泵殼、復(fù)式接頭和自動(dòng)剎車(chē)部件。

第四單元

? Introduction

引言

Forging is an important hot-forming process.It is used in producing components of all shapes and sizes, from quite small items to large units weighing several tons.鍛造是一種重要的熱成型工藝。它能用于生產(chǎn)各種形狀和尺寸、從很小到重量數(shù)噸的零件。

Forging is the process by which metal is heated and is shaped by plastic deformation by suitably applying compressive force.Usually the compressive force is in the form of hammer blows using a power hammer or a press, as shown in Fig.4.1.在鍛造過(guò)程中先將金屬加熱，然后施加合適的壓力使其塑性變形。通常壓力都是以由如圖4.1所示的動(dòng)力錘或壓力機(jī)提供的錘擊形式出現(xiàn)。

Hand forging tools comprise variously shaped hammers.The base on which the work is supported during forging is the anvil.手工鍛造工具包括各種不同形狀的錘子。在鍛造中用于支撐工件的基礎(chǔ)是鐵砧。

For the semimechanized forging of small to medium-sized components, forging hammers powered by various means are employed.The feature common to all of them is that, like the hand forging hammer, they utilize the energy of a falling weight to develop the pressure needed for shaping the metal.對(duì)小到中等尺寸零件的半機(jī)械化鍛造而言，鍛錘可采用多種動(dòng)力。就其一般特性而言，都象手工鍛錘一樣，它們均利用落重能量來(lái)產(chǎn)生金屬成型所需的壓力。

Larger components are forged by means of forging presses operated by steam or compressed air or by hydraulic or electric power.Largely automatic forging machines are used for the quantity production of engineering parts.鍛造大零件則要用到蒸汽、壓縮空氣、液力或電力驅(qū)動(dòng)的鍛壓機(jī)。大型的自動(dòng)化鍛機(jī)用于工程零件的批量生產(chǎn)。A distinction may be made between open-die forging, usually in the form of hammer forging, and closed-die forging.In hammer forging, the component is shaped by hammer blows aided by relatively simple tools.These may include open dies i.e., dies that do not completely enclose the metal to be shaped.錘鍛中常用的開(kāi)式模鍛與閉式模鍛是有區(qū)別的。在錘鍛中零件通過(guò)錘擊輔之以相對(duì)簡(jiǎn)單的工具成型。其中包括開(kāi)式鍛模，就是不完全封閉被成型金屬的模具。

One of the basic operations of hammer forging is the elongation of a piece of metal by stretching with hammer blows, causing it to become thinner and longer.In hand forging the work-piece is usually turned 90°after each blow, in order to forge it thoroughly and prevent its lateral expansion.錘鍛的基本操作之一就是通過(guò)錘擊使金屬伸長(zhǎng)，促成其變細(xì)變長(zhǎng)。手工鍛造時(shí)一般在每次錘擊后都轉(zhuǎn)過(guò)90°以充分鍛打工件并防止橫向膨脹。

The opposite of elongation is upsetting, which produces compressive shortening.For example, the diameter of a bar can be increased by heating and hammering axially.與伸長(zhǎng)相反的是鐓粗，即產(chǎn)生壓縮性縮短。例如，棒料的直徑可以通過(guò)加熱和軸向錘擊而增大。

More important is closed-die forging, very widely used for mass production in industry, in which the metal is shaped

by pressing between a pair of forging dies.The upper die is usually attached to the ram of a forging press or a forging hammer, while the lower die is stationary.更重要的是閉式模鍛，在工業(yè)上廣泛用于規(guī)模生產(chǎn)。閉式模鍛中金屬在一對(duì)鍛模之間擠壓成型。頂模通常放在鍛壓機(jī)的撞頭或鍛錘上，而底模則是固定的。

Together they form a closed die.Closed-die forging can produce components of greater complexity and accuracy, with a better surface finish than the more traditional methods not using closed dies.The dies are made of special heat-resistant and wear-resistant tool steels.兩者合在一起形成閉式鍛模。閉式模鍛能生產(chǎn)高度復(fù)雜和精確的零件，而且表面光潔度要比不用閉式鍛模的更傳統(tǒng)方法好。閉式鍛模采用特殊的耐熱、耐磨工具鋼制成。

A piece of hot metal sufficient to slightly overfill the die shape is placed in the bottom die, and the top die is forced against it, so that the metal takes the internal shape of the die.將一塊大小足以充填模腔并能稍有溢出的加熱金屬放入底模，并將頂模加壓合攏，這塊金屬便獲得該模腔的形狀。

Closed-die forging is used for the rapid production of large numbers of fairly small parts and also for very large components.For the latter, e.g., modern jet-aircraft components, giant hydraulically operated presses are used, which can develop forces of 50,000 tons and more.閉式模鍛用于相當(dāng)小的零件大批量快速生產(chǎn)，也可用于很大的零件。對(duì)后者而言，例如現(xiàn)代噴氣飛機(jī)零件，使用能產(chǎn)生50,000噸以上壓力的巨型液力鍛壓機(jī)。

One valuable feature of forging is that it improves the strength of the metal by refining the structure and making it uniform;so for heavy forgings, such as marine propeller shafts, an immensely powerful hydraulic press squeezes the metal with a force sometimes as great as 10,000 tonnes.鍛造有價(jià)值的特性之一是它通過(guò)使金屬組織均勻而改善強(qiáng)度，因此對(duì)諸如船舶螺旋槳軸之類的重型鍛件，要用能達(dá)10,000噸壓力的龐大而有力的液壓機(jī)來(lái)擠壓金屬。

Although the hydraulic forging press is a more expensive piece of equipment than a drop-forge, it has advantages beside those of giving greater strength and more uniform structure to large components.On account of the high pressure and squeezing action, it operates with less noise and vibration than a drop-forge.雖然這種液壓鍛機(jī)比落錘鍛造要昂貴得多，但它除了能給予大零件較高的強(qiáng)度和更均勻的組織外還有其它優(yōu)點(diǎn)。由于較高的壓力和擠壓作用，它比落錘鍛造噪聲及振動(dòng)都小得多。

As ingots of steel weighing 30 tonnes or more are forged in this way, manual operation is impossible and it is essential that all the manipulation of the ingot is done mechanically.由于這種情況下被鍛鋼坯重量大于30噸，人工操作是不可能的，鋼坯的所有操作都必須是機(jī)械化的。Forging refines the grain structure and improves physical properties of the metal.With proper design, the grain flow

can be oriented in the direction of principal stresses encountered in actual use.鑄造細(xì)化金屬的晶粒組織、改善其物理性能。通過(guò)適當(dāng)?shù)脑O(shè)計(jì)，可以使晶粒流動(dòng)方向與實(shí)際使用時(shí)的主應(yīng)力方向一致。

As shown in Fig.4.2, grain flow is the direction of the pattern that the crystals take during plastic deformation.Physical properties(such as strength, ductility and toughness)are much better in a forging than in the base metal, which has crystals randomly oriented.如圖4.2所示，晶粒流動(dòng)的方向就是在塑性變形期間結(jié)晶排列的方向。鍛件的物理性能(如強(qiáng)度、延展性和韌性)遠(yuǎn)好于基礎(chǔ)金屬，因?yàn)榛A(chǔ)金屬的晶粒是無(wú)序排列的。

Forgings are consistent from piece to piece, without any of the porosity, voids, inclusions and other defects.Thus, finishing operations such as machining

do not expose voids, because there aren’t any.Also coating operations such as plating or painting are straightforward due to a good surface, which needs very little preparation.鍛件各部分是連貫一致的，沒(méi)有孔隙、空洞、雜質(zhì)及其它缺陷。因此像機(jī)加工之類的精加工工序不會(huì)受空洞的影響，因?yàn)楦揪筒淮嬖?。另外由于鍛件良好的表面，像電鍍或油漆之類的涂裝工序就很簡(jiǎn)單，幾乎不需要做準(zhǔn)備工作。

Forgings yield parts that have high strength to weight ratio, thus are often used in the design of aircraft frame members.A forged metal can result in the following: 鍛造生產(chǎn)的零件具有較高的強(qiáng)度重量比，所以常被用在飛機(jī)結(jié)構(gòu)零件的設(shè)計(jì)中。鍛造金屬可以導(dǎo)致下列結(jié)果：

? Increase length, decrease cross-section, called drawing out the metal.? Decrease length, increase cross-section, called upsetting the metal.? Change length, change cross-section, by squeezing in closed impression dies.This results in favorable grain flow for strong parts.●增加長(zhǎng)度、減小橫截面，稱為延伸金屬?！駵p小長(zhǎng)度、增加橫截面，稱為鐓粗金屬?！裢ㄟ^(guò)用封閉鍛模擠壓，改變長(zhǎng)度和橫截面。這導(dǎo)致有利的晶粒流使零件堅(jiān)固。

? Common Forging Processes 常用的鍛造工藝

The metal can be forged hot(above recrystallization temperatures)or cold.金屬既可熱鍛(高于再結(jié)晶溫度)也可冷鍛。

Open die forgings/Hand forgings.Open die forgings or hand forgings are made with repeated blows in an open die, where the operator manipulates the workpiece in the die.The finished product is a rough approximation of the die.This is

what a traditional blacksmith does, and is an old manufacturing process.開(kāi)式模鍛/手工鍛：開(kāi)式模鍛或手工鍛就是操作者操縱工件在開(kāi)式鍛模中反復(fù)擊打。完成的產(chǎn)品是鍛模的粗糙近似物。這就是傳統(tǒng)鐵匠干的活，是較古老的制造工藝。

Impression die forgings/Precision forgings.Impression die forgings and precision forgings are further refinements of the blocker forgings.The finished part more closely resembles the die impression.壓模鍛/精密鍛：壓模鍛和精密鍛是雛形模鍛的進(jìn)一步改進(jìn)。完成的零件與模膛更相似。

Press forgings.Press forgings use a slow squeezing action of a press, to transfer a great amount of compressive force to the workpiece.Unlike an open-die forging where multiple blows transfer the compressive energy to the outside of the product, press forging transfers the force uniformly to the bulk of the material.壓鍛：壓鍛通過(guò)壓力機(jī)緩慢的擠壓動(dòng)作將巨大的壓力傳遞給工件。不像開(kāi)式模鍛那樣需要多次擊打把壓縮能量傳遞到零件外表面，壓鍛能將力均勻地傳遞給材料的主體。

This results in uniform material properties and is necessary for large weight forgings.Parts made with this process can be quite large as much as 125kg(260lb)and 3m(10 feet)long.這使材料性能一致，對(duì)大重量鍛件而言是十分必要的。采用此工藝生產(chǎn)的零件重量可達(dá)125kg(260lb)而長(zhǎng)度可達(dá)3m(10 feet)。

Upset forgings.Upset forging increases cross-section by compressing the length, this is used in making heads on bolts and fasteners, valves and other similar parts.頂鍛：頂鍛通過(guò)壓縮長(zhǎng)度增加橫截面，用于在螺栓等緊固件、柱塞及類似零件上制造頭部。

Roll forgings.In roll forging, a bar stock, round or flat is placed between die rollers which reduces the cross-section and increases the length to form parts such as axles, leaf springs etc.This is an essential form of draw forging.滾鍛：在滾鍛時(shí)，圓的或是扁平的棒料放在模輥之間縮小橫截面增加長(zhǎng)度制成諸如輪軸、板簧之類的零件。這是軋鍛的基本形式。

Swaging.Swaging—a tube or rod is forced inside a die and the diameter is reduced as the cylindrical object is fed.The die hammers the diameter and causes the metal to flow inward causing the outer diameter of the tube or the rod to take the shape of the die.型鍛：型鍛—將圓管或圓棒強(qiáng)制壓入鍛模，隨著圓柱形物體的被壓入其直徑減小。鍛模錘擊橫斷面使金屬向內(nèi)流動(dòng)導(dǎo)致圓管或圓棒的外徑變?yōu)殄懩５男螤睢?/p>

Net shape/Near-net shape forging.In net shape or near-net shape forging, forging results in wastage of material in the form of material flash and subsequent machining operations, as shown in Fig.4.3.This wastage can be as high as 70% for gear blanks, and even 90% in the case of aircraft structural parts.純型/近似純型鍛 ：采用純型鍛或近似純型鍛，產(chǎn)生材料損耗的主要形式是飛邊以及隨后的機(jī)加工，如圖4.3所示。齒輪毛坯材料損耗為70%，而飛機(jī)結(jié)構(gòu)零件的材料損耗甚至達(dá)90%。

Net-shape and near-net-shape processes minimize the waste by making precision dies, producing parts with very little draft angle(less than 1°).These types of processes often eliminate or reduce machining.純型鍛和近似純型鍛工藝通過(guò)制作精密模具并生產(chǎn)鍛模斜角很小(小于1°)的零件能使材料損耗最小化。此類工藝通?？梢允∪セ驕p少機(jī)加工。

The processes are quite expensive in terms of tooling and the capital expenditure required.Thus, these processes can be only justified for current processes that are very wasteful where the material savings will pay for the significant increase in tooling costs.從模具的角度而言這些工藝是相當(dāng)昂貴的，需要資金投入。因此這些工藝只有對(duì)目前很浪費(fèi)的生產(chǎn)過(guò)程，在材料節(jié)約足以補(bǔ)償模具成本的大量增加時(shí)才是合理的。

? Die Design Consideration 鍛模設(shè)計(jì)的考慮因素

? Parting surface should be along a single plane if possible, else following the contour of the part.The parting surface should be through the center of the part, not near the upper or lower edges.? 如果可能分模面應(yīng)沿著單一平面，否則就順著零件輪廓方向。分模面應(yīng)經(jīng)過(guò)零件中心，而不要靠近上下邊緣。

If the parting line cannot be on a single plane, then it is good practice to use symmetry of the design to minimize the side thrust forces.Any point on the parting surface should be less than 75°from the principal parting plane.如果分模面不能在單一平面，利用設(shè)計(jì)的對(duì)稱性來(lái)減小側(cè)向推力不失為一種好方法。分模面上任意點(diǎn)與主分模面的夾角應(yīng)小于75°。

? As in most forming processes, use of undercuts should be avoided as these will make the removal of the part difficult, if not impossible.? 如同大多數(shù)成型工藝，如果不是非用不可，盡量避免采用凹槽，因?yàn)榘疾蹠?huì)使零件難以取出。? Generous fillets and radius should be provided to aid in material flow during the forging process.Sharp corners are stress-risers in the forgings, as well as make the dies weak in service.? Ribs should not be high or narrow;this makes it difficult for the material to flow.? 應(yīng)提供盡可能大的倒角和半徑以幫助材料在鍛造過(guò)程中流動(dòng)。銳角會(huì)增加鍛件中的應(yīng)力，同時(shí)在使用時(shí)削弱鍛模。

? 加勁肋不要過(guò)高、過(guò)窄，因?yàn)檫@會(huì)造成材料流動(dòng)困難。? Tolerances

公差

? Dimension tolerances are usually positive and are approximately 0.3% of the dimension, rounded off to the next higher 0.5mm(0.020in.).? 尺寸公差通常為正，大約取為該尺寸的0.3%，并圓整到較大的0.5mm(0.020in.)。

? Die wear tolerances are lateral tolerances(parallel to the parting plane)and are roughly +0.2% for copper alloys to +0.5% for aluminum and steel.? 鍛模磨損公差為側(cè)向公差(平行于分模面)，對(duì)銅合金大約為+0.2%，對(duì)鋁和鋼大約為+0.5%。? Die closure tolerances are in the direction of opening and closing, and range from 1mm(0.040in.)for small forgings, die projection area＜150cm2(23in.2), to 6.25mm(0.25in.)for large forgings, die projection area＞6,500cm2(100in.2).? 鍛模的閉合公差處于開(kāi)閉的方向上，范圍從對(duì)較小鍛件[其投影面積＜150cm2(23in.2)]取為1mm(0.040in.)，到較大鍛件[其投影面積＞6,500cm2(100in.2)]取為6.25mm(0.25in.)。

? Die match tolerances are to allow for shift in the upper die with respect to the lower die.? 鍛模的配合公差是為了允許上模能根據(jù)下模替換。

A proper lubricant is necessary for making good forgings.The lubricant is useful in preventing sticking of the workpiece to the die, and also acts as a thermal insulator to help reduce die wear.制造良好的鍛件必須有合適的滑潤(rùn)劑。滑潤(rùn)劑對(duì)防止工件粘住鍛模很有用，還可以作為絕熱體幫助減少鍛模磨損。

第五單元

Powder metallurgy(Fig.5.1)uses sintering process for making various parts out of metal powder.The metal powder is compacted by placing in a closed metal cavity(the die)under pressure.粉末冶金(圖5.1)采用燒結(jié)工藝將金屬粉末制成各種各樣的零件。金屬粉末放在封閉的金屬腔(模具)中在壓力下被壓實(shí)。

This compacted material is placed in an oven and sintered in a controlled atmosphere at high temperatures and the metal powders coalesce and form a solid.A Second pressing operation, repressing, can be done prior to sintering to improve the compaction and the material properties.被壓實(shí)的材料置于爐內(nèi)燒結(jié)，在高溫下?tīng)t內(nèi)環(huán)境可控，金屬粉末熔合形成固體。在燒結(jié)前可以進(jìn)行二次擠壓作

業(yè)(再擠壓)以改善壓實(shí)狀態(tài)和材料性能。

Powder metallurgy is a highly developed method of manufacturing reliable ferrous and nonferrous parts.Made by mixing elemental or alloy powders and compacting the mixture in a die, the resultant shapes are then sintered or heated in a controlled atmosphere furnace.粉末冶金是一種高度發(fā)達(dá)的制造可靠鐵或非鐵零件的方法。通過(guò)混合元素或合金粉末并在模具中壓實(shí)混合物，再燒結(jié)或在環(huán)境可控爐內(nèi)加熱制成最終形狀。

? Material

材料

The majority of the structural components produced by fixed die pressing are iron-based.The powders are elemental, pre-alloyed, or partially alloyed.大多數(shù)用固定模壓制的結(jié)構(gòu)件都是鐵基的。粉末可以是單一元素、預(yù)先合金或部分合金。

Elemental powders, such as iron and copper, are easy to compress to relatively high densities, produce pressed compacts with adequate strength for handling during sintering, but do not produce very high strength sintered parts.諸如鐵、銅之類的單一元素粉末較容易被壓得相對(duì)密度較高、生產(chǎn)具備足夠強(qiáng)度的壓制物供燒結(jié)處理，但是無(wú)法制造出很高強(qiáng)度的燒結(jié)零件。

Pre-alloyed powders are harder, less

compressible and hence require higher pressing loads to produce high density compacts.However, they are capable of producing high strength sintered materials.預(yù)先合金粉末比較硬、不容易壓實(shí)，因此需要較高的擠壓力來(lái)產(chǎn)生高密度的壓制物。然而它們能生成高強(qiáng)度燒結(jié)材料。

Pre-alloying is also used when the production of a homogeneous material from elemental powders requires very high temperatures and long sintering times.The best examples are the stainless steels, whose chromium and nickel contents have to be pre-alloyed to allow economic production by powder metallurgy.如果用單一元素粉末生產(chǎn)均勻材料需要很高溫度和較長(zhǎng)燒結(jié)時(shí)間，也可用預(yù)先合金。最好的例子是不銹鋼，因含有鉻和鎳成分，所以粉末冶金必須用預(yù)先合金才經(jīng)濟(jì)。

Partially alloyed powders are a compromise approach.Elemental powders, e.g.iron with 2wt.% copper, are mixed to produce an homogeneous blend which is then partially sintered to attach the copper particles to the iron particles without producing a fully diffused powder but retaining the powder form.部分合金粉末是一種折衷的方法。單一元素粉末，例如鐵與2%的銅(重量百分比)混合均勻，經(jīng)部分燒結(jié)后銅微粒粘附到鐵微粒上而沒(méi)有產(chǎn)生充分?jǐn)U散的粉末卻保留了粉末的形態(tài)。

In this way the compressibilities of the separate powders in the blend are maintained and the blend will not segregate during transportation and use.用這種方法混合物中單獨(dú)粉末的可壓縮性得以維持，在運(yùn)送和使用期間結(jié)合將不會(huì)分離。

A similar technique is to “glue” the small percentage of alloying element onto the iron powder.This “glueing”

technique is successfully used to introduce carbon into the blends, a technique which prevents carbon segregation and dusting, producing so-called “clean” powders.另一種類似的技術(shù)是把小百分比的合金元素“粘合”到鐵微粒上。這種“粘合”技術(shù)已成功用于將碳引入結(jié)合物，一種防止碳分離并起塵的技術(shù)，生產(chǎn)所謂的“清潔”粉末。

? Powder Consolidation 粉末合成

Components or articles are produced by forming a mass of powder into a shape, then consolidating to form inter-particle metallurgical bonds.通過(guò)將大量的粉末放入模具成型為零件或物品，然后合成為內(nèi)有微粒的冶金結(jié)合物。

An elevated temperature diffusion process referred to as sintering, sometimes assisted by external pressure, accomplishes this.The material is never fully molten, although there might be a small volume fraction of liquid present during the sintering process.Sintering can be regarded as welding the particles present in the initial useful shape.提升溫度擴(kuò)散工藝被稱為燒結(jié)，有時(shí)還輔之以外界的壓力來(lái)達(dá)到目的。雖然在燒結(jié)過(guò)程中可能會(huì)有少量液態(tài)出現(xiàn)，但材料決不是全熔化。燒結(jié)可以被看作是把微粒焊接成初始的有用形狀。

As a general rule both mechanical and physical properties improve with increasing density.Therefore the method selected for the fabrication of a component by powder metallurgy will depend on the level of performance required from the part.Many components are adequate when produced at 85~90% of theoretical full density whist others require full density for satisfactory performance.作為普遍規(guī)律，隨著密度的增加機(jī)械和物理性能均改善。因此選擇何種粉末冶金方法來(lái)制作零件取決于其所需的性能級(jí)別。許多零件只需理論全密度的85~90%而其它的則需全密度才能滿足要求。

Some components, in particular bush type bearings often made from copper and its alloys, are produced with significant and controlled levels of porosity, the porosity being subsequently filled with a lubricant.Fortunately there is a wide choice of consolidation techniques available.有些零件，尤其是襯套式軸承常用銅及其合金制作，控制多孔性程度的意義重大，因?yàn)檫@些孔隨后要填充潤(rùn)滑劑。

還好有多種合成技術(shù)可供選擇。Cold Uniaxial Pressing Elemental metal, or an atomized pre-alloyed powder is mixed with a lubricant, typically lithium stearate(0.75 wt.%), and pressed at pressures of say, 600MPa(87,000lb/in.2)in metal dies.冷單向擠壓

單一元素金屬，或極小顆粒的預(yù)先合金粉末與潤(rùn)滑劑(一般是鋰硬脂酸鹽，重量百分比0.75%)混合，然后在金屬模具中施加壓力[比如600MPa(87,000lb/in.2)]擠壓。

Cold compaction ensures that the as-compacted, or “green”, component is dimensionally very accurate, as it is moulded precisely to the size and shape of the die.冷擠壓能保證被壓制或“未加工”的零件尺寸十分精確，因?yàn)樗痪_地按模具的尺寸和形狀成型。One disadvantage of this technique is the differences in pressed density that can occur in different parts of the component due to particle/particle and die wall/particle frictional effects.Typical as-pressed densities for soft iron components would be 7.0g/cc, i.e.about 90% of theoretical density.這種技術(shù)的缺點(diǎn)之一是由于微粒/微粒和模壁/微粒間的摩擦效應(yīng)，零件不同部位的壓實(shí)密度存在差異。典型的軟鐵零件壓制密度為7.0g/cc，即大約是理論密度的90%。

Compaction pressure rises significantly if higher as-pressed densities are required, and this practice becomes uneconomic due to higher costs for the larger presses and stronger tools to withstand the higher pressures.如果需要較高的壓實(shí)密度則壓實(shí)壓力要顯著提高，因?yàn)榇笮蛪毫C(jī)成本較高并且在較高壓力下模具強(qiáng)度要更高這樣就不合算。

Cold Isostatic Pressing Metal powders are contained in an enclosure e.g.a rubber membrane or a metallic can that is subjected to isostatic, which is uniform in all directions, external pressure.As the pressure is isostatic the as-pressed component is of uniform density.冷均衡擠壓

金屬粉末裝入均衡受壓的橡膠膜或金屬罐內(nèi)，其所受外壓力在各個(gè)方向都是均勻的。由于壓力是均衡的，所以壓制零件密度是均勻的。

Irregularly shaped powder particles must be used to provide adequate green strength in the as-pressed component.This will then be sintered in a suitable atmosphere to yield the required product.必須采用不規(guī)則形狀粉末微粒為壓制零件提供足夠的未加工強(qiáng)度。然后放入合適的環(huán)境中燒結(jié)成所需產(chǎn)品。Normally this technique is only used for semi-fabricated products such as bars, billets, sheet, and roughly shaped components, all of which require considerable secondary operations to produce the final, accurately dimensioned component.通常這種技術(shù)只用于制作諸如棒料、坯段、薄板及粗糙成型零件之類的半成品，所有這些都需要大量進(jìn)一步加工才能生產(chǎn)出最終尺寸精確的零件。

Again, at economical working pressures, products are not fully dense and usually need additional working such as hot extrusion, hot rolling or forging to fully density the material.此外使用經(jīng)濟(jì)工作壓力的產(chǎn)品不是充分致密的，一般需要增加諸如熱擠壓、熱軋或鍛之類的額外工序來(lái)使材料達(dá)到全密度。

Sintering

Sintering is the process whereby powder compacts are heated so that adjacent particles fuse together, thus resulting in a solid article with improved mechanical strength compared to the powder compact.燒結(jié)

燒結(jié)就是通過(guò)把粉末壓制物加熱使鄰近的微粒熔合在一起的工藝，它能生成比粉末壓制物機(jī)械強(qiáng)度更好的固體物。

This “fusing” of particles results in an increase in the density of the part and hence the process is sometimes called densification.There are some processes such as hot isostatic pressing which combine the compaction and sintering processes into a single step.微粒的“熔合”導(dǎo)致零件密度增加，因此該工藝有時(shí)被稱為致密化。還有一些工藝如熱均衡擠壓，將壓實(shí)和燒結(jié)工藝合并為單一步驟。

After compaction the components pass through a sintering furnace.This typically has two heating zones, the first removes the lubricant, and the second higher temperature zone allows diffusion and bonding between powder particles.零件壓實(shí)后通過(guò)燒結(jié)爐。一般有兩個(gè)加熱區(qū)，第一個(gè)去除潤(rùn)滑劑，第二個(gè)溫度更高的區(qū)域讓粉末微粒之間擴(kuò)散并結(jié)合。

A range of atmospheres, including vacuum, are used to sinter different materials depending on their chemical compositions.As an example, precise atmosphere control allows iron/carbon materials to be produced with specific carbon compositions and mechanical properties.根據(jù)不同材料的化學(xué)成分，燒結(jié)的環(huán)境包括真空狀態(tài)也各不相同。例如精確的環(huán)境控制可使鐵/碳材料生成特殊碳化物和機(jī)械性能。

The density of the component can also change during sintering, depending on the materials and the sintering temperature.These dimensional changes can be controlled by an understanding and control of the pressing and sintering parameters, 根據(jù)材料和燒結(jié)溫度的不同，零件的密度在燒結(jié)過(guò)程中也會(huì)改變。因?yàn)槌叽绲淖兓梢酝ㄟ^(guò)了解并調(diào)節(jié)擠壓及燒結(jié)參數(shù)進(jìn)行控制，and components can be produced with dimensions that need little or no rectification to meet the dimensional tolerances.Note that in many cases all of the powder used is present in the finished product, scrap losses will only occur when secondary machining operations are necessary.所以零件尺寸幾乎無(wú)需校正就能滿足尺寸公差?？梢钥吹皆诤芏嗲闆r下所有使用的粉末都包含在制成品中，廢料損失僅產(chǎn)生于需要輔助機(jī)加工時(shí)。

Hot Isostatic Pressing Powders are usually encapsulated in a metallic container but sometimes in glass.The container is evacuated, the powder out-gassed to avoid contamination of the materials by any residual gas during the consolidation stage and

sealed-off.熱均衡擠壓

粉末通常封裝在金屬容器內(nèi)有時(shí)也裝在玻璃容器內(nèi)。把容器抽真空，粉末抽氣是為了防止材料在合成階段和密封時(shí)被殘留氣體污染。

It is then heated and subjected to isostatic pressure sufficient to plastically deform both the container and the powder.再加熱并施加均衡壓力足以使容器和粉末都塑性變形。

The rate of densification of the powder depends upon the yield strength of the powder at the temperatures and pressures chosen.At moderate temperature the yield strength of the powder can still be high and require high pressure to produce densification in an economic time.粉末致密率取決于該粉末在選定溫度和壓力下的屈服強(qiáng)度。中等溫度下粉末的屈服強(qiáng)度仍然較高，因此需要較高壓力使其在經(jīng)濟(jì)時(shí)間內(nèi)致密化。

Typical values might be 1120℃ and 100MPa for ferrous alloys.By pressing at very much higher temperatures lower pressures are required as the yield strength of the material is lower.Using a glass enclosure atmospheric pressure(15psi)is used to consolidate bars and larger billets.對(duì)鐵合金典型的數(shù)值為1120℃和100MPa。由于很高溫度下材料的屈服強(qiáng)度較低，因此只需較低壓力就能擠壓。采用玻璃容器時(shí)可用大氣壓力(15psi)合成棒料和較大坯段。

The technique requires considerable financial investment as the pressure vessel has to withstand the internal gas pressure and allow the powder to be heated to high temperatures.因?yàn)閴毫θ萜鞅仨毥?jīng)受住內(nèi)氣壓并允許粉末加熱到較高溫度，所以這種技術(shù)需要相當(dāng)可觀的資金投入。As with cold isostatic pressing only semi-finished products are produced, either for subsequent working to smaller sizes, or for machining to finished dimensions.此工藝與采用冷均衡擠壓一樣只能生產(chǎn)半成品，可以通過(guò)后續(xù)加工至較小尺寸，也能用機(jī)加工到最終尺寸。Hot Forging(Powder Forging)Cold pressed and sintered components have the great advantage of being close to final shape(near-net shape), but are not fully dense.Where densification is essential to provide adequate mechanical properties, the technique of hot forging, or powder forging, can be used.熱鍛(粉末鍛造)冷擠壓和燒結(jié)零件主要優(yōu)點(diǎn)是接近最終形狀(近似純形)，但不是充分致密的。當(dāng)為了提供足夠的機(jī)械性能而致密化是必須時(shí)，可以采用熱鍛或粉末鍛造技術(shù)。

In powder forging an as-pressed component is usually heated to a forging temperature significantly below the usual sintering temperature of the material and then forged in a closed die.This produces a fully dense component with the shape of the forging die and appropriate mechanical properties.在粉末鍛造中，壓制零件一般加熱到遠(yuǎn)低于該材料通常燒結(jié)溫度的鍛造溫度，然后在閉模中鍛造。這能生產(chǎn)具有鍛模形狀和合適機(jī)械性能的充分致密零件。

Powder forged parts generally are not as close to final size or shape as cold pressed and sintered parts.These results from the allowances made for thermal expansion effects and the need for draft angles on the forging tools.Further, minimal machining is required but when all things are considered this route is often very cost-effective.粉末鍛造零件通常不像冷擠壓和燒結(jié)零件那樣接近最終尺寸或形狀。這是由于為熱膨脹效應(yīng)而設(shè)置允差以及在鍛模上需要拔模斜角所致。此外還需少量機(jī)加工，但全面考慮這種方法通常還是很劃算的。

Metal Injection Moulding(MIM)Injection moulding is very widely used to produce precisely shaped plastic components in complex dies.As injection pressures are low it is possible to manufacture complex components, even some with internal screw threads, by the use of side cores and split tools.金屬注塑成型(MIM)注塑成型被很廣泛地用于在復(fù)雜模具中生產(chǎn)形狀精確的塑料零件。注塑壓力較低使得制作復(fù)雜零件成為可能，通過(guò)采用側(cè)面型芯和分離工具甚至可以帶有內(nèi)螺紋。

By mixing fine, typically less than 20 μm diameter, spherical metal powders with thermoplastic binders, metal filled plastic components can be produced with many of the features available in injection moulded plastics.After injection moulding, the plastic binder material is removed to leave a metal skeleton which is then sintered at high temperature.將細(xì)小(直徑一般小于20μm)球形金屬粉末與熱塑性粘合劑混合，能生產(chǎn)具有多數(shù)注塑成型塑料特征的金屬充滿塑料零件。注塑成型后，去除塑料粘合材料剩下金屬骨架，然后在高溫下燒結(jié)。

Dimensional control can be exercised on the as-sintered component as the injected density is sensibly uniform so shrinkage on sintering is also uniform.燒結(jié)零件可以實(shí)現(xiàn)尺寸控制，因?yàn)樽⑺苊芏让黠@均勻，所以燒結(jié)收縮也是均勻的。

Shrinkage can be large, due to both the fine particle size of the powders and the substantial proportion of polymer binder used.由于所用粉末細(xì)小微粒的尺寸和聚合物粘合劑的真實(shí)比例，收縮可以比較大。

? Features

特征

? For high tolerance parts, a sintering part is put back into a die and repressed.In genera this makes the part more accurate with a better surface finish.? 對(duì)較大公差的零件，燒結(jié)后可放回模具重新擠壓。一般而言這會(huì)使零件更精確同時(shí)具有更好的表面光潔度。

? A part has many voids that can be impregnated.One method is to use an oil bath.Another method uses vacuum first, then impregnation.? 零件有許多可供填充的空間。一種方法是采用油浴。另一種方法是先抽真空然后再充滿。? A part surface can be infiltrated with a low melting point metal to increase density, strength, hardness, ductility and impact resistance.? Plating, heat treating and machining operations can also be used.? 零件表面能被低熔點(diǎn)金屬滲透以增大密度、強(qiáng)度、硬度、延展性和抗沖擊能力。? 仍然可以進(jìn)行電鍍、熱處理和機(jī)加工作業(yè)。? Advantages

優(yōu)點(diǎn)

? Good tolerances and surface finish ? Highly complex shapes made quickly ? Can produce porous parts and hard to manufacture materials(e.g.cemented oxides)? 良好的公差和表面光潔度 ? 高度復(fù)雜的形狀能快速制作

? 能制作多孔零件和難以加工材料(如粘結(jié)氧化物)? Pores in the metal can be filled with other materials/metals ? Surfaces can have high wear resistance ? Porosity can be controlled ? Low waste ? Automation is easy ? 金屬中的氣孔可用其它材料/金屬填充 ? 表面能具有較高的耐磨性 ? 孔隙率可以控制 ? 較低損耗 ? 容易自動(dòng)化

? Physical properties can be controlled ? Variation from part to part is low ? Hard to machine metals can be used easily ? No molten metals ? 物理性能可以控制 ? 零件之間的變化較小

? 難以機(jī)加工的金屬能被容易使用 ? 無(wú)需熔化金屬

? No need for many/any finishing operations

? Permits high volume production of complex shapes ? Allows non-traditional alloy combinations ? Good control of final density ? 不需要很多/任何修整作業(yè) ? 允許加工復(fù)雜形狀的大體積產(chǎn)品 ? 允許非傳統(tǒng)合金結(jié)合 ? 對(duì)最終密度能很好地控制 ? Disadvantages

缺點(diǎn)

? Metal powders deteriorate quickly when stored improperly ? Fixed and setup costs are high ? Part size is limited by the press and compression of the powder used ? 如果存放不當(dāng)金屬粉末質(zhì)量很快降低 ? 安裝和調(diào)整的成本較高

? 零件尺寸受壓力機(jī)和所用粉末壓縮的限制

? Sharp corners and varying thickness can be hard to produce ? Non-moldable features are impossible to produce ? 銳角和變厚度較難加工 ? 不適合模壓的東西不可能生產(chǎn)

第六單元

Injection molding(Fig.6.1)is the predominant process for fabrication of thermoplastics into finished forms, and is increasingly being used for thermosetting plastics, fiber-filled composites, and elastomers.注塑成型(圖6.1)是將熱塑性塑料制成最終形狀的主要工藝，并且越來(lái)越多地用于熱硬化性塑料、纖維填充合成物和人造橡膠。

It is the process of choice for tremendous variety of parts ranging in weight from 5g to 85kg.It is estimated that 25% of all thermoplastics are injection molded.它是重量范圍為5g到85kg極大一類零件可選用的工藝。估計(jì)所有熱塑性塑料中有25%是采用注塑成型的。If newer modifications, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase.如果考慮到新近的改進(jìn)(例如反作用注塑成型)和采用塑料替代金屬的高增長(zhǎng)率，注塑成型在世界范圍的工業(yè)重

要性很可能將繼續(xù)增加。

Currently, probably close to half of all major processing units is injection molding machines.In 1988, a dollar sale of new injection molding machinery in the U.S.was approximately 65% of total major polymer machinery sales volume;this included 4,600 injection molding units.當(dāng)前，大概所有主要處理設(shè)備的近一半是注塑成型機(jī)。1988年，美國(guó)新的注塑成型機(jī)械銷(xiāo)售約占全部主要聚合物機(jī)械銷(xiāo)售量的65%，其中包括4,600臺(tái)注塑成型設(shè)備。

The machines and their products are ubiquitous and are synonymous with plastics for many people.這類機(jī)械和它們的產(chǎn)品普遍存在，對(duì)許多人來(lái)說(shuō)與塑料是同義的。

A reciprocating screw injection molding machine combines the functions of an extruder and a compressive molding press.往復(fù)螺旋注射成型機(jī)把壓出機(jī)和成型壓力機(jī)的功能結(jié)合起來(lái)。

It takes solid granules of thermoplastic resin, melts and pressurizes them in the extruder section, forces the melt at high velocity and pressure through carefully designed flow channels into a cooled mold, then ejects the finished part(s), and automatically recycles.把熱塑性塑料樹(shù)脂的固體顆粒在壓出部分融化并增壓，迫使其高速融化并通過(guò)仔細(xì)設(shè)計(jì)的流動(dòng)通道進(jìn)入冷卻模具，噴射成最終零件，然后自動(dòng)再循環(huán)。

This machine is a descendant of the plunger type “stuffing machine” patented by the Hyatt brothers in 1872 to mold celluloid.In 1878, the Hyatts developed the first multicavity mold, but it was not until 1938 that Quillery(France)patented a machine incorporating a screw to plasticize the elastomer being molded.這種機(jī)械是1872年Hyatt兄弟獲得專利權(quán)的融化賽璐珞的活塞型“填充機(jī)”的派生物。1878年Hyatt兄弟開(kāi)發(fā)了第一個(gè)多槽模具，但直到1938年Quillery(法國(guó))才發(fā)明了用螺旋增塑人造橡膠并使其成型的一體化機(jī)械。

In 1956, Ankerwerk Nuremberg commercialized the modern reciprocating screw injection molding machine for thermoplastics.Today, over 50 machine manufacturers are listed in Modern Plastics Encyclopedia, offering machines to the U.S.market ranging from 2 to 6,000 tons clamping capacity.1956年，Ankerwerk Nuremberg使用于熱塑性塑料的現(xiàn)代往復(fù)螺旋注塑成型機(jī)商業(yè)化。今天，已有超過(guò)50家制造商列入現(xiàn)代塑料制品百科全書(shū)，能為美國(guó)市場(chǎng)提供壓制能力從2到6,000噸的機(jī)械。

(A machine with a 10,000-ton capacity has been built to mold 264-gallon HDPE trash containers.)A host of suppliers of auxiliary equipment, molds, instruments, and controls service this major segment of the polymer industry.(一臺(tái)能力為10,000噸用于成型264加侖高密度聚乙烯垃圾箱的機(jī)械也已制成)。許多輔助設(shè)備、模具、儀器和控制系統(tǒng)供應(yīng)商在為聚合物工業(yè)的這一主要部分服務(wù)。

Injection molding is particularly worthy of intensive study because it combines many areas of interest extrusion, mold design, rheology, sophisticated hydraulic and electronic controls, robotic accessories, design of complex products, and, of

course, the integration of materials science and process engineering.注塑成型對(duì)深入研究很有價(jià)值，因?yàn)樗Y(jié)合了許多重要領(lǐng)域，如擠壓、模具設(shè)計(jì)、流變學(xué)、完備的液壓和電子控制、機(jī)器人配件、復(fù)雜產(chǎn)品的設(shè)計(jì)，當(dāng)然還有材料科學(xué)與加工工程的綜合。

The objectives of injection molding engineers are simple enough: to obtain minimum cycle time with minimum scrap, to attain specified product performance with assurance, to minimize production costs due to downtime or any other reasons, and to steadily increase in expertise and competitiveness.注塑成型工程師的目標(biāo)很簡(jiǎn)單：在最少?gòu)U料的情況下取得最小循環(huán)時(shí)間，在有保證的情況下獲得指定產(chǎn)品性能，將由停工或其它原因產(chǎn)生的生產(chǎn)成本最小化，還有穩(wěn)定地增加專門(mén)知識(shí)和競(jìng)爭(zhēng)力。

Profit margins for custom injection molders are said to be generally skimpy;an established way to improve profits is to be selected for more demanding, higher margin jobs that demand the highest level of efficiency and competence.傳統(tǒng)的注塑成型機(jī)利潤(rùn)盈余據(jù)說(shuō)一般是不足的；為了更多需求及更高盈余工作需要選擇一種改善利潤(rùn)的確定方法，它要求最高水平的效率和能力。

This text will concentrate on the reciprocating screw machine for thermoplastics, which has largely replaced the older reciprocating plunger types except for very small-capacity machines.本文將集中論述熱塑性塑料用的往復(fù)螺旋機(jī)，除了小容量機(jī)械外它已在很大程度上取代了較老的往復(fù)活塞式機(jī)械。

? Injection Molding Materials 注塑成型材料

It is not possible to injection-mold all polymers.Some polymers like PTFE(Poly-tetra-fluoro-ethylene), cannot be made to flow freely enough to make them suitable for injection molding.要注塑成型所有聚合物是不可能的。像聚四氟乙烯之類的聚合物就不能自由流動(dòng)得足以適合注塑成型。Other polymers, such as a mixture of resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process.In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.其它聚合物，例如樹(shù)脂和編織的或墊子形的玻璃纖維的混合物，由于它們的物理性質(zhì)不適合使用此工藝。一般而言，能進(jìn)入流動(dòng)狀態(tài)的聚合物都可以注塑成型。

The vast majority of injection molding is applied to thermoplastic polymers.This class of materials consists of polymers which always remain capable of being softened by heat and of hardening on cooling, even after repeated cycling.注塑成型的絕大多數(shù)都用于熱塑性聚合物。這類材料由具有加熱軟化、冷卻硬化甚至可重復(fù)循環(huán)能力的聚合物組成。

This is because the long-chain molecules of the material always remain as separate entities and do not form chemical bonds to one another.An analogy car, be made to a block of ice that can be softened(i.e.turned back to liquid), poured

into any shape cavity, and then cooled to become a solid again.這是由于這類材料的長(zhǎng)鏈分子總是保持分離的實(shí)體并不相互形成化學(xué)連結(jié)。一輛由冰塊制成的模擬汽車(chē)，可以融化(即轉(zhuǎn)化為液態(tài))，倒入任何形狀的空腔，然后冷卻重新變成固體。

This property differentiates thermoplastic materials from thermosetting ones.In the latter type of polymer, chemical bonds are formed between the separate molecule chains during processing.In this case the chemical bonding referred to as cross linking is the hardening mechanism.這個(gè)特性將熱塑性材料與熱硬化性材料區(qū)分開(kāi)。后者在加工過(guò)程中分離的分子鏈之間形成化學(xué)連結(jié)。在此情況下作為交聯(lián)的化學(xué)連結(jié)是硬化機(jī)制。

In general, most of the thermoplastic materials offer high impact strength, corrosion resistance, and easy processing with good flow characteristics for molding complex designs.Thermoplastics are generally divided into two classes: namely crystalline and amorphous.一般而言，大多數(shù)熱塑性材料具有較高的抗沖擊強(qiáng)度、耐腐蝕性以及良好流動(dòng)性使其容易加工而適于復(fù)雜成型設(shè)計(jì)。熱塑性塑料通常分為兩類：即結(jié)晶質(zhì)的和非結(jié)晶質(zhì)的。

Crystalline polymers have an ordered molecular arrangement, with a sharp melting point.Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque.結(jié)晶質(zhì)聚合物具有規(guī)則的分子排列及明顯的熔點(diǎn)。由于規(guī)則的分子排列，結(jié)晶質(zhì)聚合物能反射大多數(shù)特定光線并一般表現(xiàn)為不透明的。

They also undergo a high shrinkage or reduction in volume during solidification.Crystalline polymers usually are more resistant to organic solvents and have good fatigue and wear-resistant properties.Crystalline polymers also generally are denser and have better mechanical properties than amorphous polymers.它們?cè)诠袒^(guò)程中收縮較大或體積減少較多。結(jié)晶質(zhì)聚合物通常多能抵御有機(jī)溶劑并具有良好的抗疲勞和磨損特性。結(jié)晶質(zhì)聚合物通常也比非結(jié)晶質(zhì)聚合物更致密并且具有更好的機(jī)械性能。

The main exception to this rule is polycarbonate, which is the amorphous polymer of choice for high quality transparent moldings, and has excellent mechanical properties.其中主要例外是聚碳酸酯，它是可選用做高質(zhì)量透明注塑件的非結(jié)晶質(zhì)聚合物，并具有卓越的機(jī)械性能。The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement.This takes the form of short-chopped fibers, a few millimeters in length, which are randomly mixed with the thermoplastic resin.就本質(zhì)而言，熱塑性塑料的機(jī)械性能低于金屬，但可以通過(guò)加入玻璃纖維強(qiáng)化予以增強(qiáng)來(lái)適應(yīng)某些運(yùn)用。常用幾毫米長(zhǎng)的短碎纖維隨機(jī)地與熱塑性樹(shù)脂混合。

The fibers can occupy up to one third of the material volume to considerably improve the material strength and stiffness.The negative effect of this reinforcement is usually a decrease in impact strength and an increase in abrasiveness.纖維可占材料體積的三分之一以極大改善材料的強(qiáng)度和硬度。這種加強(qiáng)的負(fù)作用通常是抗沖擊強(qiáng)度降低及磨損性增加。

The latter also has an effect on processing since the life of the mold cavity is typically reduced from about 1,000,000 parts for plain resin parts to about 300,000 for glass-filled parts.后者對(duì)加工過(guò)程也有影響，因?yàn)槟＞咔坏膲勖鼜牡湫偷钠胀?shù)脂零件大約1,000,000件減少到玻璃纖維填充樹(shù)脂零件的約300,000件。

Perhaps the main weakness of injection-molded parts is the relatively low service temperatures to which they can be subjected.Thermoplastic components can only rarely be operated continuously above 250℃, with an absolute upper service temperature of about 400℃.注塑成型零件的主要缺點(diǎn)或許是它們能承受的工作溫度相對(duì)較低。熱塑性塑料零件只有很少能連續(xù)運(yùn)行在250℃以上，其絕對(duì)最高工作溫度約為400℃。

The temperature at which a thermoplastic can be operated under load can be defined qualitatively by the heat deflection temperature.This is the temperature at which a simply supported beam specimen of the material, with a centrally applied load, reaches a predefined deflection.熱塑性塑料帶載運(yùn)行溫度可從質(zhì)量上定義為熱偏差溫度。這是中心承載的該材料簡(jiǎn)支梁達(dá)到預(yù)定偏差的溫度。The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test values are only really useful for comparing different polymers.其溫度值明顯取決于試驗(yàn)條件和允許偏差，因此對(duì)比較不同的聚合物而言只有試驗(yàn)數(shù)據(jù)是真正有用的。

? Cycle of Operation 作業(yè)循環(huán)

The reciprocating screw injection molding machine is considered as consisting of two halves: a fixed injection side, and a movable clamp side.往復(fù)螺旋注塑成型機(jī)被認(rèn)為由兩部分組成：一個(gè)固定注塑端和一個(gè)活動(dòng)夾具端。

The injection side contains the extruder that receives solid resin in pellet or granular form and converts it into a viscous liquid or melt that can be forced through the connecting nozzle, spine, and runners to the gates that lead into the mold cavities.注塑端包含壓出機(jī)，它接受小球或粒狀的固體樹(shù)脂，然后將其轉(zhuǎn)化為粘性液體或稱為融化，再?gòu)?qiáng)迫其通過(guò)連接噴嘴、中心和澆道到閘道進(jìn)入模具腔。

The mold is tightly clamped against injection pressure and is cooled well below the melt temperature of the thermoplastic.When the parts in the cavities have cooled sufficiently the mold halves are opened at the mold parting plane and the parts ejected by a knockout system drop into a receiving bin below.模具被緊緊地夾住以抵抗注塑壓力，并在熱塑性塑料的融化溫度以下很好地冷卻。當(dāng)模腔內(nèi)的零件充分冷卻，剖分模在模具分模面處打開(kāi)，推出系統(tǒng)將零件推出落入下面的接收容器內(nèi)。

This summarizes the overall cycle, but leaves out much vital detail that is necessary for understanding the process.However, with this introduction, it is possible to understand the advantages and disadvantages of the process.這概述了整個(gè)循環(huán)，但省略了許多對(duì)理解此工藝所必需的很重要細(xì)節(jié)。然而通過(guò)本介紹，了解這種工藝的優(yōu)缺點(diǎn)仍是可能的。

? Effects of Process Variables on Orientation

加工變量對(duì)方向性的影響

In injection molding, any variation in processing that keeps the molding resin hot throughout filling allows increased relaxation and, therefore, decreased orientation.Some of the steps that can be taken to reduce orientation are as follows.在注塑成型時(shí)，整個(gè)填料過(guò)程始終保持成型樹(shù)脂高溫的任何加工變化都會(huì)增加松弛作用而減少方向性。下面是可以用于減少方向性的若干措施。

? Faster injection(up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning;better flow to corners;and less

crystallinity all favor lower subsurface orientation.The primary effect is that the gate will freeze more quickly.At that point, orientation stops and relaxation starts.? 較快注塑(到點(diǎn))：在填料過(guò)程中冷卻較少，因此初始固化層較薄，由于剪應(yīng)變稀少而粘性較低；能較好地流到角落；結(jié)晶度較小；所有這些促成表面下的方向性也較低。主要效果是閘道將較快固化。這樣使得方向性停止產(chǎn)生而松弛作用開(kāi)始增加。

? Higher melt and mold temperatures: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.? Reduced packing time and pressure: overpacking inhibits relaxation processes.? 較高的融化和成型溫度：融化粘性較低，更容易填充，較大松弛作用促成方向性減少。? 減少擠壓時(shí)間和壓力：過(guò)度擠壓會(huì)抑制松弛過(guò)程。

? Reduced gate size: larger gates take longer to freeze off and permit increased orientation.? 減小閘道尺寸：閘道越大則固化時(shí)間越長(zhǎng)并會(huì)使方向性增加。

Excessively high injection speed can cause high surface orientation and increase susceptibility to stress cracking.For example, moldings that are to be electroplated, and will be subject to acid solutions during plating, must be made using very slow injection speeds to minimize surface orientation.過(guò)高的注塑速度會(huì)引起較高的表面方向性及增加應(yīng)力破裂的敏感性。例如，要電鍍的注塑件在電鍍時(shí)會(huì)經(jīng)受酸溶液，必須采用很低的注塑速度制造以使表面方向性最小化。

On the other hand, the transverse motion component of the melt front in most moldings can cause transverse subsurface orientation superimposed on the primary orientation, giving a desirable biaxial orientation effect.另一方面，大多數(shù)注塑件的融化前部橫向運(yùn)動(dòng)部分能導(dǎo)致在主要方向性上有層理的表面下橫向方向性，產(chǎn)生需要的雙軸方向性效應(yīng)。

Orientation can be seriously increased by obstructions to flow during filling of the cavity.Flow around an obstruction causes a decrease in melt front speed and leads to high local viscosity and reduced relaxation.This is also likely to occur near the end of the filling phase if gating is inadequate.在填充模腔時(shí)流動(dòng)受到阻礙會(huì)極大地增加方向性。圍繞障礙物流動(dòng)使融化前部的速度下降并產(chǎn)生較高的局部粘性而減少松弛作用。如果閘道不適當(dāng)，這也很可能發(fā)生在接近填充結(jié)束階段。

The molder must recognize the dangers of excessive fill speed, insufficient injection pressure, excessive melt temperature, and inadequate packing.These dangers are weighed against the opposing effects on orientation discussed above.注塑工必須認(rèn)識(shí)過(guò)快填充速度、不足注塑壓力、過(guò)高融化溫度和不充分?jǐn)D壓的危害性。這些危害性要與上述方向性的反向效應(yīng)相權(quán)衡。

Thicker parts delay cooling and increase relaxation time and tend to result in lower orientation.Thicker parts also tend to warp less.Therefore, a minimum wall thickness can be established by experience for various shapes, materials, and process combinations.較厚零件會(huì)延遲冷卻并且增加松弛時(shí)間，趨向于導(dǎo)致較低的方向性。較厚零件也有助于減少翹曲。因此，對(duì)各種形狀、材料和工藝組合能通過(guò)經(jīng)驗(yàn)來(lái)確定最小壁厚。

Lower molecular weight and broader molecular weight distribution in thermoplastics favor lower orientation and reduced internal stress in moldings.在熱塑性塑料中較小的分子量以及較寬泛的分子量分布促成方向性減少同時(shí)降低注塑件中的內(nèi)應(yīng)力。The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation;that is, it decreases as the melt or mold temperatures and cavity pressure increases.Tensile strength and stiffness increase as skin thickness ratio increases.Microscopic examination thus provides another way of studying the process efficiently.外殼厚度比受加工變量影響的方式與方向性預(yù)測(cè)一樣；也就是它能隨融化或成型溫度及模腔壓力的增加而減少。拉伸強(qiáng)度和硬度隨外殼厚度比增加而增加。因而顯微鏡檢查提供了有效研究該工藝的另一方法。

? Advantages

優(yōu)點(diǎn)

1.High production rates.For example, a CD disk can be produced with a 10~12s cycle in high melt flow index PC.1.高生產(chǎn)率：例如，一張CD盤(pán)在高融體流動(dòng)指數(shù)生產(chǎn)控制中只需10~12s一個(gè)循環(huán)就能生產(chǎn)出來(lái)。2.Relatively low labor content.One operator can frequently take care of two or more machines, particularly the moldings are unloaded automatically onto conveyors.2.相對(duì)較少的工作內(nèi)容：一個(gè)操作者經(jīng)?？梢哉湛磧膳_(tái)以上機(jī)械，尤其是當(dāng)成品能自動(dòng)卸到輸送機(jī)上時(shí)。3.Parts require little or no finishing.For example, flash can be minimized and molds can be arranged to automatically

separate runners and gates from the part itself.4.Very complex shapes can be formed.Advances in mold tooling are largely responsible.3.零件幾乎不需要修整：例如，飛邊可以最小化并且模具能被設(shè)計(jì)成自動(dòng)將澆道和閘道從零件本身分離。4.非常復(fù)雜的形狀也能成型：模具的進(jìn)步很大程度上是可靠的。

5.Flexibility of design(finishes, colors, inserts, materials).More than one material can be molded through co-injection.Foam core materials with solid skins are efficiently produced.Thermosetting plastics and fiber-reinforced shapes are injection molded.5.設(shè)計(jì)的靈活性(光潔度、顏色、插入物、材料)：通過(guò)復(fù)合注塑可以成型多于一種材料。可以高效地生產(chǎn)帶有固體外殼的泡沫型芯材料。熱硬化性塑料和纖維加強(qiáng)形狀都可以注塑成型。

6.Minimum scrap loss.Runners, gates, and scrap can usually be reground.Recycled thermoplastics can be injection molded.6.廢料損失最小化：澆道、閘道和廢料通常可以重新研磨。循環(huán)熱塑性塑料可以注塑成型。

7.Close tolerances are obtainable.Modern microprocessor controls, fitted to precision molds, and elaborate hydraulics, facilitate tolerances in the 0.1% range on dimensions and weights(but not without a high level of operational skills in constant attendance).7.能得到接近的公差：現(xiàn)代微處理器控制、合適的精密模具和精心制作的液壓設(shè)備使得尺寸和重量的公差保持在0.1% 的范圍內(nèi)(但不是沒(méi)有在持續(xù)照看時(shí)的高水平操作技能)。

8.Makes best use of the unique attributes of polymers, such as flow ability, light weight, transparency, and corrosion resistance.This is evident from the number and variety of molded plastic products in everyday use.8.充分利用聚合物諸如流動(dòng)能力、重量輕、透明和耐腐蝕等獨(dú)特屬性：從日常使用成型塑料產(chǎn)品的數(shù)量和種類就能明顯看到。

? Disadvantages and Problems 缺點(diǎn)和問(wèn)題

1.High investment in equipment and tools requires high production volumes.2.Lack of expertise and good preventive maintenance can cause high startup and running costs.1.較高的設(shè)備和模具投資需要較高生產(chǎn)量才合算。

2.缺少專門(mén)技術(shù)和良好的預(yù)防性維修會(huì)導(dǎo)致較高的啟動(dòng)和運(yùn)行成本。

3.Quality is sometimes difficult to determine immediately.For example, post-mold warpage may render parts unusable because of dimensional changes that are not completed for weeks or months after molding.3.質(zhì)量有時(shí)難以馬上確定。例如，成型后的翹曲會(huì)導(dǎo)致零件不能用，因?yàn)樵诔尚秃髱仔瞧谏踔翈讉€(gè)月尺寸變化都不能完成。

4.Attention is required on many details requiring a wide variety of skills and cross-disciplinary knowledge.5.Part design sometimes is not well suited to efficient molding.4.對(duì)許多需要廣泛多樣性技能和交叉學(xué)科知識(shí)的細(xì)節(jié)必須加以注意。5.零件設(shè)計(jì)有時(shí)不能很好地適應(yīng)有效率的成型。

6.Lead time for mold design, mold manufacture and debugging trials is sometimes very long.6.模具設(shè)計(jì)、模具制造和調(diào)試試驗(yàn)這些先導(dǎo)工作有時(shí)要花費(fèi)很長(zhǎng)時(shí)間。

第七單元

The importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.(1)In USA, more than $100 billions are spent annually on machining and related operations.機(jī)加工過(guò)程的重要性可通過(guò)日常生活使用的每件產(chǎn)品都直接或間接經(jīng)歷這一過(guò)程的事實(shí)來(lái)強(qiáng)調(diào)。(1)在美國(guó)，每年花在機(jī)加工及其相關(guān)作業(yè)上的費(fèi)用都多于千億美元。

(2)A large majority(above 80%)of all the machine tools used in the manufacturing industry have undergone metal cutting.(3)An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.(2)用于制造業(yè)的全部機(jī)床中的大多數(shù)(多于80%)都經(jīng)歷過(guò)金屬切削。(3)有估計(jì)顯示美國(guó)生產(chǎn)的所有金屬中約10到15%轉(zhuǎn)變成了切屑。

These facts show the importance of metal cutting in general manufacturing.It is therefore important to understand the metal cutting process in order to make the best use of it.這些事實(shí)說(shuō)明了金屬切削在常規(guī)制造中的重要性。因此了解金屬切削過(guò)程以充分利用它是重要的。A number of attempts have been made in understanding the metal cutting process and using this knowledge to help improve manufacturing operations which involved metal cutting.在了解金屬切削過(guò)程并運(yùn)用這些知識(shí)幫助改善與金屬切削有關(guān)的制造作業(yè)方面已經(jīng)做了許多努力。A typical cutting tool in simplified form is shown in Fig.7.1.The important features to be observed are follows.典型切削刀具的簡(jiǎn)化形式如圖7.1所示。要注意的重要特征如下。

1.Rake angle.It is the angle between the face of the tool called the rake face and the normal to the machining

direction.Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.1.前角：它是被稱為前傾面的刀具面與垂直機(jī)加工方向的夾角。前角越大，則切削越好且切削力越小，增加前角可以減少刀具前傾面上產(chǎn)生的金屬阻塞。

This reduces the strength of the tool tip as well as the heat dissipation through the tool.Thus, there is a maximum limit to the rake angle and this is generally of the order of 15°for high speed steel tools cutting mild steel.It is possible to have rake angles at zero or negative.但這會(huì)和減少通過(guò)刀具散發(fā)的熱量一樣減少刀尖強(qiáng)度。因此前角有一最大限制，用高速鋼刀具切削低碳鋼通常為15°。前角取零度或負(fù)值也是可能的。

2.Clearance angle.This is the angle between the machined surface and the underside of the tool called the flank face.The clearance angle is provided such that the tool will not rub the machined surface thus spoiling the surface and increasing the cutting forces.A very large clearance angle reduces the strength of the tool tip, and hence normally an angle of the order of 5~6°is used.2.后角：這是機(jī)加工面與被稱為后側(cè)面的刀具底面夾角。后角使刀具不產(chǎn)生會(huì)損壞機(jī)加工面的摩擦和增加切削力。很大的后角會(huì)削弱刀尖的強(qiáng)度，因此一般采用5~6°的后角。

The conditions which have an important influence on metal cutting are work material, cutting tool material, cutting tool geometry, cutting speed, feed rate, depth of cut and cutting fluid used.對(duì)金屬切削有重要影響的條件有工件材料、刀具材料、刀具幾何形狀、切削速度、進(jìn)給率、切削深度和所用的切削液。

The cutting speed, v, is the speed with which the cutting tool moves through the work material.This is generally expressed in metres per second(ms-1).切削速度v指切削刀具經(jīng)過(guò)工件材料的移動(dòng)速度。通常用米每秒(ms-1)表示。

Feed rate, f, may be defined as the small relative movement per cycle(per revolution or per stroke)of the cutting tool in a direction usually normal to the cutting speed direction.Depth of cut, d, is the normal distance between the unmachined surface and the machined surface.進(jìn)給率f可定義為每循環(huán)(每轉(zhuǎn)或每行程)切削刀具在通常為垂直于切削速度方向的次要相對(duì)運(yùn)動(dòng)。切削深度d是未加工面與已加工面之間的垂直距離。

? Chip Formation 切屑的形成

Metal cutting process is a very complex process.Fig.7.2 shows the basic material removal operation schematically.金屬切削過(guò)程是一個(gè)很復(fù)雜的過(guò)程。圖7.2用圖的形式顯示了基本材料去除作業(yè)。

The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically.This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent

metal.在刀具前傾面前的金屬直接受到壓縮，首先彈性變形然后塑性變形?？紤]到最終形狀中的材料是通過(guò)剪切從母體金屬去除的，此區(qū)域傳統(tǒng)上稱為剪切區(qū)。

The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip.Then the deformed metal(called chip)flows over the tool(rake)face.金屬的實(shí)際分離始于屈服或斷裂(視切削條件而定)，從切削刀尖開(kāi)始。然后變形金屬(稱為切屑)流過(guò)刀具(前傾)面。

If the friction between the tool rake face and the underside of the chip(deformed material)is considerable, then the chip gets further deformed, which is termed as secondary deformation.The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.如果刀具前傾面與切屑(變形金屬)底面之間的摩擦相當(dāng)大，那么切屑進(jìn)一步變形，這也叫做二次變形?；^(guò)刀具前傾面的切屑被提升離開(kāi)刀具，切屑彎曲的結(jié)果被稱為切屑卷。

Plastic deformation can be caused by yielding, in which case strained layers of material would get displaced over other layers along the slip-planes which coincide with the direction of maximum shear stress.屈服能導(dǎo)致塑性變形，在這種情況下材料變形層沿著與最大剪應(yīng)力方向一致的滑移面被其它層所取代。A chip is variable both in size and shape in actual manufacturing practice.Study of chips is one of the most important things in metal cutting.As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.在實(shí)際加工過(guò)程中切屑的尺寸和形狀都是變化的。對(duì)切屑的研究是金屬切削最重要的事情之一。如同后面將要看到的那樣，金屬切削力學(xué)極大地依賴于所產(chǎn)生切屑的形狀和尺寸。

Chip formation in metal cutting could be broadly categorised into three types:(Fig.7.3)(1)Discontinuous chip(2)Continuous chip(3)Continuous chip with BUE(Built up edge)金屬切削中的切屑形成可以寬泛地分成三個(gè)類型(圖7.3)：(1)間斷切屑(2)連續(xù)切屑

(3)帶切屑瘤的連續(xù)切屑

Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other.Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.間斷切屑：分段的切屑分散成小碎片，既可能相互附著也可能不相互附著。在靠近切削面處發(fā)生金屬的劇烈變形，導(dǎo)致在運(yùn)動(dòng)刀具前方金屬層產(chǎn)生裂縫。

Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation.With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.最后，橫過(guò)切屑的剪切應(yīng)力與材料的剪切強(qiáng)度相等，造成斷裂和分離。生成這類切屑時(shí)，切屑沿刀具面幾乎沒(méi)有相對(duì)運(yùn)動(dòng)，見(jiàn)圖7.3a。

Continuous chip.The continuous chip is characterized by a general flow of the separated metal along the tool face.There may be some cracking of the chip, but in this case it usually does not extend far enough to cause fracture.連續(xù)切屑：連續(xù)的切屑一般具有分離金屬沿刀具面流動(dòng)的特征。切屑可能有一些破裂，但在這種情況下切屑通常不會(huì)延長(zhǎng)到足以引起斷裂。

This chip is formed at the higher cutting speeds when machining ductile materials.There is little tendency for the material to adhere to the tool.The continuous chip usually shows a good cutting ratio and tends to produce the optimum surface finish, but it may become an operating hazard, Fig.7.3b.這種切屑形成于用較高切削速度機(jī)加工有延展性的材料時(shí)。材料幾乎沒(méi)有粘附刀具的傾向。連續(xù)切屑通常具有良好的切削率和趨向于產(chǎn)生最適宜的表面光潔度，但可能成為操作的危險(xiǎn)之源，見(jiàn)圖7.3b。

Continuous with a built-up edge.This chip shows the existence of a localized, highly deformed zone of material attached or “welded” on the tool face.帶切屑瘤的連續(xù)切屑：這種切屑顯示了粘合或“焊接”在刀具面上材料局部高度變形區(qū)的存在。

Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.實(shí)際上，對(duì)顯微照片的分析顯示這種切屑瘤受到靜摩擦力抑制直至它變得大到作用在它上面的外力使其移動(dòng)，一些留在機(jī)加工表面上而另一些延伸到切屑的背面，見(jiàn)圖7.3c。

? Shear Zone

剪切區(qū)

There are basically two schools of thought in the analysis of the metal removal process.One school of thought is that the deformation zone is very thin and planar as shown in Fig.7.4a.The other school thinks that the actual deformation zone is a thick one with a fan shape as shown in Fig.7.4b.在對(duì)金屬去除過(guò)程的分析中主要存在兩種思想學(xué)派。一種思想學(xué)派認(rèn)為變形區(qū)如圖7.4a所示那樣非常薄而平坦。另一學(xué)派則認(rèn)為真實(shí)變形區(qū)象圖7.4b所示那樣為一厚的帶有扇形的區(qū)域。

Though the first model(Fig.7.4a)is convenient from the point of analysis, physically it is impossible to exist.This is because for the transition from undeformed material to deform to take place along a thin plane, the acceleration across the plane has to be infinity.雖然第一種模型(圖7.4a)從分析的角度看是方便的，但實(shí)際上是不可能存在的。這是由于未變形的材料沿著剪切面發(fā)生變形，而且越過(guò)剪切面的加速度無(wú)窮大。