第一篇：機(jī)械專業(yè)英語

機(jī)械專業(yè)英語楊亞炬 20100334506

機(jī)電103班

考慮磨削力的磁懸浮磨床電主軸轉(zhuǎn)子系統(tǒng)動態(tài)特性分析

摘要:以電磁軸承支承的磨床也主軸為研究對象，建立了轉(zhuǎn)子的彈性支承模型，對其進(jìn)行了模態(tài)分析，得出轉(zhuǎn)子固有頻率隨支承剛度變化的規(guī)律;對施加磨削力時轉(zhuǎn)子的穩(wěn)態(tài)響應(yīng)特性進(jìn)行了分析，根據(jù)危險界面的節(jié)點位移，初步確定了主軸系統(tǒng)的穩(wěn)定性。

關(guān)鍵詞:電磁軸承支承系統(tǒng);磨床電主軸;模態(tài)分析;穩(wěn)態(tài)響應(yīng)特性 引言

電磁軸承具有無摩擦、元磨損、高速度、高精度及可長期免維護(hù)等優(yōu)點，因此被廣泛應(yīng)用于高速旋轉(zhuǎn)類機(jī)械中。采用電磁軸承支承的磨床電主軸是典型的機(jī)電一體化系統(tǒng)，由于磨削過程的復(fù)雜性，其支承主軸系統(tǒng)的影響與其他軸承相比更為突出[1 刀。轉(zhuǎn)子的動態(tài)特性是電磁軸承支承特性與轉(zhuǎn)子結(jié)構(gòu)動力學(xué)特性綜合作用的結(jié)果。在對轉(zhuǎn)子實施控制之前，研究轉(zhuǎn)子本身的動力學(xué)行為對控制系統(tǒng)的設(shè)計是很重要的時。本文以某電磁軸承支承的磨床電主軸為研究對象，建立了轉(zhuǎn)子的彈性支承模型，對其進(jìn)行了模態(tài)分析和施加磨削力時的穩(wěn)態(tài)響應(yīng)特性分析。軸、砂輪連接桿、前后徑向軸頸套、前后平衡環(huán)、止推盤和隔磁環(huán)等組成，其他部件與轉(zhuǎn)軸之間采用過盈連接。

轉(zhuǎn)子總重5.90kg，總長507mm，穩(wěn)定懸浮時轉(zhuǎn)子和徑向軸承之間的間隙為0.2mm，軸向軸承

1.砂輪2 傳感器3.前輔助軸承4.前徑向軸承5.轉(zhuǎn)軸6.軸向軸承7.冷卻水套

8.電機(jī)部分9.后徑向軸承10.后輔助軸承間隙為0.3mm。建立有限元模型

電磁軸承支承為典型的彈性支承，有限元分析模型采用16 個彈簧單元模擬徑向電磁軸承的16 個磁極。止推盤兩側(cè)分別采用8 個彈簧轉(zhuǎn)軸 根據(jù)轉(zhuǎn)子的結(jié)構(gòu)形式，用ANSYS 建立起轉(zhuǎn)子的實體有限元分析模型，模態(tài)分析

支承剛度對轉(zhuǎn)子固有頻率的影晌根據(jù)轉(zhuǎn)子的有限元分析模型，用ANSYS 對其進(jìn)行模態(tài)分析[5J。忽略彈簧單元的阻尼，支承剛度在5X106~lXI09N/m 范圍內(nèi)變化階模態(tài)，得到轉(zhuǎn)子的正進(jìn)動固有頻率和負(fù)進(jìn)動固有頻率，進(jìn)一步研究臨界轉(zhuǎn)速時，首先剔除負(fù)進(jìn)動固有頻率[6J。可以得到轉(zhuǎn)軸前四階固有頻率隨剛度變化曲線,轉(zhuǎn)子的正進(jìn)動固有頻率隨支承剛度的增大而增大，且轉(zhuǎn)子的低階固有頻率隨支承剛度增加的幅度較大。當(dāng)支承剛度增大到1.6X10 8 N/m 時，轉(zhuǎn)子的2~4 階固有頻率已無多

模態(tài)分析完畢后，將磨削激振力施加于砂輪 處進(jìn)行諧響應(yīng)分析，在砂輪外圓節(jié)點7746 處施加Y 方向力(實部為88.328N、虛部為1.9737N)和Z 方向力(實部為1.9737N、虛部為88.328N)，這樣磨削力為一簡諧力。COMBIN14 單元的剛度取2.0X10 7 N/m，為分析轉(zhuǎn)子在高頻段的響應(yīng)，將激振力的頻率范圍擴(kuò)大至0~1600Hz，分20 個載荷步進(jìn)行諧響應(yīng)分析。

當(dāng)主軸工作在30000r/ min(對應(yīng)額定工作頻率500.0Hz)、48 OOOr/ min(對應(yīng)最高工作頻率800.OHz)，即轉(zhuǎn)速處于一階與二階臨界轉(zhuǎn)速之間時，由轉(zhuǎn)子的二階振型(圖5)可以看出，轉(zhuǎn)子在砂輪、前保護(hù)軸承、前徑向軸承和后徑向軸承處的中心截面為危險截面。圖7~ 圖10 分別為砂輪、前保護(hù)軸承、前徑向軸承和后

徑向軸承處的振動幅值一頻率響應(yīng)后徑向軸承處節(jié)點4484 振動幅值一頻率響應(yīng)曲線移增大幅值在一階固有頻率處最小，二階固有頻率處最大，三階固有頻率處次之。

磨床電主軸的結(jié)構(gòu)參數(shù)如下:轉(zhuǎn)子與前后保護(hù)軸承的間隙為O.lmm，與前后徑向軸承的間隙為0.2mm。由表3 可知，當(dāng)激振力頻率達(dá)到轉(zhuǎn)子一階、三階固有頻率時，轉(zhuǎn)子產(chǎn)生的共振位移在轉(zhuǎn)曲線，在有限元模型上分別對應(yīng)節(jié)點7746、7818、7559 和4484 的振動幅值頻率響應(yīng)。各危險截面的節(jié)點Y 方向位移如表3 所示。當(dāng)激振力頻率達(dá)到轉(zhuǎn)子的固有頻率時，轉(zhuǎn)子的位移(振動幅值)會突然增大，通過前三階的幅頻響應(yīng)曲線可以看出，轉(zhuǎn)子位子間隙范圍之內(nèi);但達(dá)到轉(zhuǎn)子二階固有頻率時，轉(zhuǎn)子產(chǎn)生的共振位移會超出間隙要求，使得轉(zhuǎn)子與軸承碰撞，發(fā)生危險，因此應(yīng)避免激振力頻率達(dá)到轉(zhuǎn)子的二階固有頻率。由轉(zhuǎn)子的二階振型可以看出，轉(zhuǎn)子在后保護(hù)軸承處的徑向位移小于后徑向軸承處的徑向位移，故可判定后保護(hù)軸承處在Y 方向的位移小于

2.0 X 10 一7 m。各危險截面的節(jié)點位移均在間隙范圍內(nèi)，因此可初步判定轉(zhuǎn)子在額定轉(zhuǎn)速和最高

轉(zhuǎn)速下工作時，給其施加Fn = 88.328N、Ft =1.9737N 的磨削力，可穩(wěn)定工作。結(jié)論

(1)完全彈性支承下，電主軸轉(zhuǎn)子固有頻率的總體變化趨勢隨支承剛度的增大而增大，并且在支承剛度較低時，固有頻率隨支承剛度的變化較大。當(dāng)支承剛度到達(dá)一定值時，轉(zhuǎn)子的前四階固有頻率趨于穩(wěn)定，在設(shè)計控制系統(tǒng)時可控制軸承的剛度高于此值，以便轉(zhuǎn)子具有穩(wěn)定的臨界轉(zhuǎn)速。

(2)在施加了磨削激振力后，通過幅值頻率響應(yīng)分析確定了幾個危險界面的節(jié)點位移，可初步判斷主軸系統(tǒng)的穩(wěn)定性。

Dynamic Analysis for Electric Spindle Rotor System of Magnetic Levitation Grinder

Considering Grinding Force

Abstract: This paper bui1t an elastic bearing model for the rotor of grinder electric spindlesupported by electromagnet bearing and analyzed the mode of the rotor , educed the laws about therotor inherent frequencies changing along with bearing stiffness.Then, it analyzed steady stateresponse characteristics of the rotor while applying grinding force.According to the nodedisplacements of danger interface ,stability of spindle system is ensured initially.Key words: supporting system of electromagnet bearing;grinder electric spindle;mode analysis;steady state response characteristics.Introduction

Electromagnetic bearings with no friction, wear yuan, high-speed, high precision and long-term maintenance-free, etc., it is widely used in high-speed rotating machinery.The electromagnetic bearing grinder electric spindle is a typical mechatronic systems, due to the complexity of the grinding process, the supporting spindle system compared with other bearing more prominent [1 knife.The dynamic characteristics of the rotor the electromagnetic bearing characteristics and rotor structure dynamics combined result.Before control of the rotor embodiment, the study rotor dynamic behavior of the control system design is very important.An electromagnetic bearing grinder electric spindle rotor elastic support model, its modal analysis and steady-state response characteristics in the grinding force is applied.Shaft, wheel connecting rod, front and rear radial journal cover, front and rear stabilizer ring, thrust plate, and every other magnetic interference connection between the other components and the shaft.The rotor total weight of 5.90kg, Total length 507mm, stable suspension of the rotor and the radial bearing gap of 0.2mm, and the axial bearingwheel sensor 3.Former auxiliary bearing front radial bearing 5.Shaft axial bearing cooling water jacket motor section 9 after radial bearing 10 after the auxiliary bearing clearance of 0.3 mm.Finite element model

The electromagnetic bearing the typical elastic support, finite element analysis model with 16 spring element to simulate the radial magnetic bearing 16 pole.On both sides of the thrust plate 8 spring pivot

Established with ANSYS based on the structure of the rotor, the rotor solid finite element analysis model, Modal Analysis Support stiffness IMPACT natural frequency

of the rotor based on the finite element analysis model of the rotor, modal analysis using ANSYS its [5J.The damping of the spring element is ignored, the the support stiffness 5X106 ~ lXI09N / m range order modal rotor is precession natural frequencies and negative precession natural frequency, further study of the critical speed, the first natural frequency [excluding the negative precession 6J.Can get the shaft first four natural frequency of the curve with the change in stiffness of the rotor is precession natural frequency with the support stiffness increases, and the rate of increase of the low-order natural frequency of the rotor with the bearing stiffness.The 2-4 order natural frequency of the rotor Found when the supporting stiffness increases to 1.6X10 8 N / m,Modal analysis after grinding exciting force is applied at the wheel at the harmonic response analysis, the Y direction of the force applied to the wheel outer node 7746(88 328N real part, imaginary part 1 9737N), and Z directions force(the real part of 9737N, the imaginary part of the 88 328N), so that the grinding force of a simple harmonic force.COMBIN14 element stiffness take 2.0x10 7 N / m for the analysis of the response of the rotor at high frequencies, the frequency range of the excitationforce is expanded to 0 to 1600Hz, 20 load step harmonic response analysis.Spindle 30000r / min(corresponding to the nominal operating frequency 500.0Hz), of 48 OOOr / min(corresponding to the maximum operating frequency of 800 OHZ)that speed in the first-order and second-order critical speed, the second rotor vibration type(Figure 5)can be seen, the rotor wheel, the front protective bearings, the radial bearing and the rear radial bearing at the center of a sectional view of the dangerous section.Figures 7 to 10 respectively for the wheel, the front protective bearings, the front radial bearing and a radial bearing at a frequency response of the vibration amplitude of the vibration amplitude of the radial bearing at the node 4484 frequency response curve shift increased amplitude in a The natural frequencies at the minimum, followed by the natural frequency of the second-order, third-order natural frequency.Of Grinder Spindle structure parameters are as follows: rotor protection before and after bearing clearance O.lmm the front and rear radial bearing clearance of 0.2 mm.Seen from Table 3, when the frequency of the excitation force to the rotor-order, third-order natural frequency, the resonance generated by the rotor displacement in the transfer curve in the finite element model, respectively corresponding to the nodes 7746, 7818, 7559 and 4484, the amplitude of vibration frequency response.The nodes in the Y direction of the dangerous section of the displacement shown in Table 3.When the frequency of the excitation force is reached when the natural frequency of the rotor, the rotor displacement(vibration amplitude)will suddenly increases, frequency response curve of the web through the first three can be seen, within the scope of the clearance of the rotor charts;but reached rotor Second Order natural frequency of the rotor of the resonance displacement will exceed the spacing requirements, so that the rotor and the bearing collision danger, the second natural frequency of the exciting force the frequency of the rotor should therefore be avoided.By the second-order vibration of the rotor can be seen, the radial displacement of the rotor after protection of the radial displacement of the bearing

is less than the radial bearing at the displacement of the bearings in the Y direction, it can be determined after protection Smaller

2.0 X 10 a m.Of the dangerous section of the nodal displacements gap preliminary determination rotor at rated speed and maximum

Speed work when applied to its Fn = 88.328N FT = 9737N grinding force can work stably.Conclusions

(1)fully resilient support, the overall trend of the natural frequency of the electro-spindle rotor with bearing stiffness increases, and the supporting rigidity is low, the larger the change of the natural frequency with the support stiffness.When the supporting rigidity reaches a certain value, the first four natural frequencies of the rotor is stabilized in the design of the control system can control the stiffness of the bearing is higher than this value, the stability of the critical speed for the rotor having.(2)In the grinding exciting force is applied by the amplitude frequency response analysis identified several risk interface nodal displacements can determine the initial stability of the spindle system.

第二篇：大學(xué)機(jī)械專業(yè)英語總結(jié)

Unit 11 Machine tools have evoled from the early foot-powered lathes of the Egyptians and John Wilkinson’s boring mill.Most machining operations produce parts of differing geometry.Flat or plain surfaces are frequently required.Multiple-edged tools can also be used.The basic operations performed on an engine lathe are illustrated in Fig11-3.Those operations performed on external surfaces with a single point cutting tool are called turning.The objective of boring a hole in a lathe is:

1.Toenlarge the hole 2,Tomachine the hole to the desired diameter.3.To accurately locate the position of the hole.4.To obtion a smoth surface finish in the hole.Unit12 Broaching is a process for internal or external machining of falt, round, or contoured surfaces.Sawing is the parting of material by using metal disks, blades, bands, or abrasive disks as the cutting tools, Reaming is a machining process for enlarging, smoothing and/or accurately sizing existing holes by means of multiedge flutes cutting tools.Unit 13 Welding is essential to the expansion and productivity of our industries.Electroplating is a process in which a metal is deposited onto a metallic substrate.Soldering is the joining of metals by causing a lower-melting-point metal to wet or alloy with the joint surfaces and then freeze in place.Cleaning operations are performed both preparatory to and after finishing operations.Unit 14 Lathes are designed to rotate the workpiece and feed the cutting tool in the direction necessary togenerate the required machined surface.Vertical-boring machine

horizontal-boring machine

planning machine

horizontal-milling machine

vertical-milling machine Unit 15 AJM removes material through the mechanical cation of a focused stream of abrasiveladen gas.USM is a mechanical material removal process which is used to generate holes and cavities in hard or brittle workpieces.ECM is a process that removes material through the ptinciple of eiectrolysis.Unit 16 Group technology is a very important methodology in today’s manufacturing environment, particularly for batch production, and is becoming increasingly significant.For parts to be grouped based on either design characteristics and featuers or manufacturing processes, they must be classified into predetermined categories and coded for retrieval and use.Unit 17 Flexibility is an important characteristic in the modern manufacturing setting.Cellular manufacturing is the concept of organizing plant facilities and process planning for family-of-part manufactuer.Machine centers originsted out of their capability to perform a variety of machining operations on a workpiece by changing their own cutting tools.Software is the vital invisible element than actually drives the FMS.There are two basic levels of software required for an FMS: 1:operating system 2:application software Unit 18 Computer integrated manufacturing is the term used to describe the modern approach to manufacturing.Management is the process of making directing the activities of personnel to achieve stated objectives.An AGV is a computer-controlled, driverless vehicle used for transporting materials form point in a manufacturing setting.In any discussion of AGVs, three key terms are frequently used: 1:Guide path.2:Routing.3:Traffic management.Unit 19 Part acquisition time is highly dependent on the nature of the layout of the assenmbly area and the method of assembly.Assembly in the manufacturing process consists of putting together all the component parts and sub-assemblies of a given product, fastening, performing inspections and functional tests, labeling, separating good assemblies from bad, and packaging and or preparing them for final use.Unit 20

Automation is a widely used term in manufacturing.Fixed automation is what Harder was referring to when he coined the word automation.Numerical control can be defined as a form of programmable automation in which the pross is controlled by numbers, letters, and symbols.The program of instructions is the detailed step-by-step set of directions which tell the machine tool what to do.The highest degree of automation obtainable with special-purpose, multifunction machines is achieved by using transfer machines.

第三篇：大學(xué)機(jī)械專業(yè)英語情景對話

Mr.Liu:Come in ,please.劉先生：請進(jìn)。

Mr.Bao:Good afternoon,Mr.Liu.包先生：.下午好，劉先生。

Mr.Liu:Good afternoon.Have a seat,please.劉先生：下午好，請坐。

Mr.Bao:Thank you very much.包先生：非常感謝。

Mr.Liu:Are you Mr.Bao?

劉先生：您是包先生嗎？

Mr.Bao:Yes,I am.包先生：是的。

Mr.Liu:I have read your resume.I know you have worked for 3 years.Why did you choose to major in mechanical engineering?

劉先生：我看了你的簡歷，知道你已經(jīng)工作過3年。為什么你選擇了機(jī)械工程專業(yè)呢？ Mr.Bao:Many factors lead me to majoring in mechanical engineering.The most important factor is I like tinkering with machines.包先生：許多因素致使我選擇了這個專業(yè)。最重要的一個因素就是我喜歡修理機(jī)器。Mr.Liu:What are you interested in about mechanical engineering?

劉先生：關(guān)于機(jī)械工程，你最感興趣的是什么？

Mr.Bao:I like designing products and one of my designs received an award.Moreover,I am familiar with CAD.包先生：我喜歡設(shè)計產(chǎn)品，我的一份設(shè)計作品還得過獎。而且，我非常熟悉CAD。Mr.Liu:Great.Then what is your technical post title now?

劉先生：很好。那么你現(xiàn)在的技術(shù)職稱是什么？

Mr.Bao:I’m a senior mechanical design engineer.包先生：.我現(xiàn)在是高級機(jī)械設(shè)計工程師。

MrLiu:Do you take the original certificate with you?

劉先生：你把證書原件帶來了嗎？

Mr.Bao:Yes.Here it is.包先生：.是的，給。

Mr.Liu:Why did you decide to apply for this position?

劉先生：為什么你決定申請這份崗位？

Mr.Bao:Your company has a very good reputation.I’m very interested in the field of your company.包先生：.貴公司聲望很高。我對這領(lǐng)域也很感興趣。

Mr.Liu:Well，thanks.I’ll let you know the result of the interview as soon as possible,Goodbye.劉先生：那好吧，謝謝你。我會盡快告訴你面試結(jié)果的，再見。

Mr.Bao:Thank you.I do hope the answer will be favorable.Goodbye.包先生：謝謝，我希望結(jié)果順利。再見。

第四篇：機(jī)械專業(yè)英語文章中英文對照

英語原文

NUMERICAL CONTROL

Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols, The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work part or job.When the job changes, the program of instructions is changed.The capability to change the program is what makes N/C suitable for low-and medium-volume production.It is much easier to write programs than to make major alterations of the processing equipment.There are two basic types of numerically controlled machine tools：point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors, with the result that the position of the machining head Can be assured only upon completion of a movement, or while only one motor is running.Machines of this type are principally used for straight—line cuts or for drilling or boring.The N/C system consists of the following components：data input, the tape reader with the control unit, feedback devices, and the metal—cutting machine tool or other type of N/C equipment.Data input, also called “man—to—control link”, may be provided to the machine tool manually, or entirely by automatic means.Manual methods when used as the sole source of input data are restricted to a relatively small number of inputs.Examples of manually operated devices are keyboard dials, pushbuttons, switches, or thumbwheel selectors.These are located on a console near the machine.Dials ale analog devices usually connected to a syn-chro-type resolver or potentiometer.In most cases, pushbuttons, switches, and other similar types of selectors are digital input devices.Manual input requires that the operator set the controls for each operation.It is a slow and tedious process and is seldom justified except in elementary machining applications or in special cases.In practically all cases, information is automatically supplied to the control unit and the machine tool by cards, punched tapes, or by magnetic tape.Eight—channel punched paper tape is the most commonly used form of data input for conventional N/C systems.The coded instructions on the tape consist of sections of punched holes called blocks.Each block represents a machine function, a machining operation, or a combination of the two.The entire N/C program on a tape is made up of an accumulation of these successive data blocks.Programs resulting in long tapes all wound on reels like motion-picture film.Programs on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loop.Once installed, the tape is used again and again without further handling.In this case, the operator simply loads and1

unloads the parts.Punched tapes ale prepared on type writers with special tape—punching attachments or in tape punching units connected directly to a computer system.Tape production is rarely error-free.Errors may be initially caused by the part programmer, in card punching or compilation, or as a result of physical damage to the tape during handling, etc.Several trial runs are often necessary to remove all errors and produce an acceptable working tape.While the data on the tape is fed automatically, the actual programming steps ale done manually.Before the coded tape may be prepared, the programmer, often working with a planner or a process engineer, must select the appropriate N/C machine tool, determine the kind of material to be machined, calculate the speeds and feeds, and decide upon the type of tooling needed.The dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the program.A program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specifications.The control unit receives and stores all coded data until a complete block of information has been accumulated.It then interprets the coded instruction and directs the machine tool through the required motions.The function of the control unit may be better understood by comparing it to the action of a dial telephone, where, as each digit is dialed, it is stored.When the entire number has been dialed, the equipment becomes activated and the call is completed.Silicon photo diodes, located in the tape reader head on the control unit, detect light as it passes through the holes in the moving tape.The light beams are converted to electrical energy, which is amplified to further strengthen the signal.The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives.Some photoelectric devices are capable of reading at rates up to 1000 characters per second.High reading rates are necessary to maintain continuous machine—tool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operations.The reading device must be capable of reading data blocks at a rate faster than the control system can process the data.A feedback device is a safeguard used on some N/C installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine tool.An N/C machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop system.Positioning control is accomplished by a sensor which, during the actual operation, records the position of the slides and relays this information back to the control unit.Signals thus received ale compared to input signals on the tape, and any discrepancy between them is automatically rectified.In an alternative system, called an open—loop system, the machine is positioned solely by stepping motor drives in response to commands by a controllers.There is one basic type of NC motions.Point-to-point or Positional Control In point-to-point control the machine tool elements(tools, table, etc.)are moved to programmed locations and the machining operations performed

after the motions are completed.The path or speed of movement between locations is unimportant;only the coordinates of the end points of the motions are accurately controlled.This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece.Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining.It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined.This type of controlled motion is often referred to as linear control or a half-axis of control.Machines with this form of control are also capable of point-to-point control.The original N/C used the closed—loop system.Of the two systems, closed and open loop, closed loop is more accurate and, as a consequence, is generally more expensive.Initially, open—loop systems were used almost entirely for light-duty applications because of inherent power limitations previously associated with conventional electric stepping motors.Recent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applications.中文譯文

數(shù)控技術(shù)

數(shù)控是可編程自動化技術(shù)的一種形式,通過數(shù)字、字母和其他符號來控制加工設(shè)備。數(shù)字、字母和符號用適當(dāng)?shù)母袷骄幋a為一個特定工件定義指令程序。當(dāng)工件改變時,指令程序就改變。這種改變程序的能力使數(shù)控適合于中、小批量生產(chǎn),寫一段新程序遠(yuǎn)比對加工設(shè)備做大的改動容易得多。

數(shù)控機(jī)床有兩種基本形式：點位控制和連續(xù)控制(也稱為輪廓控制)。點位控制機(jī)床采用異步電動機(jī),因此,主軸的定位只能通過完成一個運動或一個電動機(jī)的轉(zhuǎn)動來實現(xiàn)。這種機(jī)床主要用于直線切削或鉆孔、鏜孔等場合。

數(shù)控系統(tǒng)由下列組件組成：數(shù)據(jù)輸入裝置,帶控制單元的磁帶閱讀機(jī),反饋裝置和切削機(jī)床或其他形式的數(shù)控設(shè)備。

數(shù)據(jù)輸人裝置,也稱“人機(jī)聯(lián)系裝置”,可用人工或全自動方法向機(jī)床提供數(shù)據(jù)。人工方法作為輸人數(shù)據(jù)唯一方法時,只限于少量輸入。人工輸入裝置有鍵盤,撥號盤,按鈕,開關(guān)或撥輪選擇開關(guān),這些都位于機(jī)床附近的一個控制臺上。撥號盤通常連到一個同步解析器或電位計的模擬裝置上。在大多數(shù)情況下,按鈕、開關(guān)和其他類似的旋鈕是數(shù)據(jù)輸入元件。人工輸入需要操作者控制每個操作,這是一個既慢又單調(diào)的過程,除了簡單加工場合或特殊情況,已很少使用。

幾乎所有情況下,信息都是通過卡片、穿孔紙帶或磁帶自動提供給控制單元。在傳統(tǒng)的數(shù)控系統(tǒng)中,八信道穿孔紙帶是最常用的數(shù)據(jù)輸入形式,紙帶上的編碼指令由一系列稱為程序塊的穿孔組成。每一個程序塊代表一種加工功能、一種操作或兩者的組合。紙帶上的整個數(shù)控程序由這些連續(xù)數(shù)據(jù)單元連接而成。帶有程序的長帶子像電影膠片一樣繞在盤子上,相對較短的帶子上的程序可通過將紙帶兩端連接形成一個循環(huán)而連續(xù)不斷地重復(fù)使用。帶子一旦安裝好,就可反復(fù)使用而無需進(jìn)一步處理。此時,操作者只是簡單地上、下工件。穿孔紙帶是在帶有特制穿孔附件的打字機(jī)或直接連到計算機(jī)上的紙帶穿孔裝置上做成的。紙帶制造很少不出錯,錯誤可能由編程、卡片穿孔或編碼、紙帶穿孔時的物理損害等形成。通常,必須要試走幾次來排除錯誤,才能得到一個可用的工作紙帶。

雖然紙帶上的數(shù)據(jù)是自動進(jìn)給的,但實際編程卻是手工完成的,在編碼紙帶做好前,編程者經(jīng)常要和一個計劃人員或工藝工程師一起工作,選擇合適的數(shù)控機(jī)床,決定加工材料,計算切削速度和進(jìn)給速度,決定所需刀具類型,仔細(xì)閱讀零件圖上尺寸,定下合適的程序開始的零參考點,然后寫出程序清單,其上記載有描述加工順序的編碼數(shù)控指令,機(jī)床按順序加工工件到圖樣要求。

控制單元接受和儲存編碼數(shù)據(jù),直至形成一個完整的信息程序塊,然后解釋數(shù)控指令,并引導(dǎo)機(jī)床得到所需運動。

為更好理解控制單元的作用,可將它與撥號電話進(jìn)行比較,即每撥一個數(shù)字,就儲存一個,當(dāng)整個數(shù)字撥好后,電話就被激活,也就完成了呼叫。

裝在控制單元里的紙帶閱讀機(jī),通過其內(nèi)的硅光二極管,檢測到穿過移動紙帶上的孔漏

過的光線,將光束轉(zhuǎn)變成電能,并通過放大來進(jìn)一步加強信號,然后將信號送到控制單元里的寄存器,由它將動作信號傳到機(jī)床驅(qū)動裝置。

有些光電裝置能以高達(dá)每秒1000個字節(jié)的速度閱讀,這對保持機(jī)床連續(xù)動作是必須的,否則,在輪廓加工時,刀具可能在工件上產(chǎn)生劃痕。閱讀裝置必須要能以比控制系統(tǒng)處理數(shù)據(jù)更快的速度來閱讀數(shù)據(jù)程序塊。

反饋裝置是用在一些數(shù)控設(shè)備上的安全裝置,它可連續(xù)補償控制位置與機(jī)床運動滑臺的實際位置之間的誤差。裝有這種直接反饋檢查裝置的數(shù)控機(jī)床有一個閉環(huán)系統(tǒng)裝置。位置控制通過傳感器實現(xiàn),在實際工作時,記錄下滑臺的位置,并將這些信息送回控制單元。接受到的信號與紙帶輸入的信號相比較,它們之間的任何偏差都可得到糾正。

在另一個稱為開環(huán)的系統(tǒng)中,機(jī)床僅由響應(yīng)控制器命令的步進(jìn)電動機(jī)驅(qū)動定位,工件的精度幾乎完全取決于絲杠的精度和機(jī)床結(jié)構(gòu)的剛度。有幾個理由可以說明步進(jìn)電機(jī)是一個自動化申請的非常有用的驅(qū)動裝置。對于一件事物,它被不連續(xù)直流電壓脈沖驅(qū)使,是來自數(shù)傳計算機(jī)和其他的自動化的非常方便的輸出控制系統(tǒng)。當(dāng)多數(shù)是索引或其他的自動化申請所必備者的時候,步進(jìn)電機(jī)對運行一個精確的有角進(jìn)步也是理想的。因為控制系統(tǒng)不需要監(jiān)聽就提供特定的輸出指令而且期待系統(tǒng)適當(dāng)?shù)胤磻?yīng)的公開-環(huán)操作造成一個回應(yīng)環(huán),步進(jìn)電機(jī)是理想的。一些工業(yè)的機(jī)械手使用高抬腿運步的馬乘汽車駕駛員,而且步進(jìn)電機(jī)是有用的在數(shù)字受約束的工作母機(jī)中。這些申請的大部分是公開-環(huán) ,但是雇用回應(yīng)環(huán)檢測受到驅(qū)策的成份位置是可能的。環(huán)的一個分析者把真實的位置與需要的位置作比較,而且不同是考慮過的錯誤。那然后駕駛員能發(fā)行對步進(jìn)電機(jī)的電脈沖,直到錯誤被減少對準(zhǔn)零位。在這個系統(tǒng)中,沒有信息反饋到控制單元的自矯正過程。出現(xiàn)誤動作時,控制單元繼續(xù)發(fā)出電脈沖。比如,一臺數(shù)控銑床的工作臺突然過載,阻力矩超過電機(jī)轉(zhuǎn)矩時,將沒有響應(yīng)信號送回到控制器。因為,步進(jìn)電機(jī)對載荷變化不敏感,所以許多數(shù)控系統(tǒng)設(shè)計允許電機(jī)停轉(zhuǎn)。然而,盡管有可能損壞機(jī)床結(jié)構(gòu)或機(jī)械傳動系統(tǒng),也有使用帶有特高轉(zhuǎn)矩步進(jìn)電機(jī)的其他系統(tǒng),此時,電動機(jī)有足夠能力來應(yīng)付系統(tǒng)中任何偶然事故。

最初的數(shù)控系統(tǒng)采用開環(huán)系統(tǒng)。在開、閉環(huán)兩種系統(tǒng)中,閉環(huán)更精確,一般說來更昂貴。起初,因為原先傳統(tǒng)的步進(jìn)電動機(jī)的功率限制,開環(huán)系統(tǒng)幾乎全部用于輕加工場合,最近出現(xiàn)的電液步進(jìn)電動機(jī)已越來越多地用于較重的加工領(lǐng)域。

第五篇：mechatronic(機(jī)電一體化)機(jī)械專業(yè)英語

Mechatronic

1.Introduction

Mechatronics is a design process that includes a combination of mechanical engineering, electronic engineering, material engineering, chemical engineering and industrial engineering.Mechatronics is a multidisciplinary field of engineering, that is to say, it rejects splitting engineering into separate disciplines.Nowadays, with the increasing of economy, Interdisciplinary research becomes an irreversible tendency.Which means mechatronic is facing unprecedented challenges.The old mechanics cannot catch the pace of new world, so they need to be changed.In order to stand steady from the competition, they must provide high value by being innovative during the process of transformation and upgrading.2.Mechatronic system application

Mechatronics are useful on so many fields, such as Machine vision, Automation and robotics, Servo-mechanics and so on.Mechatronic system apply to Machine vision(MV)

Mechatronic make the possibilities of MV, technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance in industry, came true.Mechatronic system apply to Automation and robotics

Imagine that just push some simple bottoms lightly can you control a huge, smart, intelligent robots.Is it only dreamed? No, it is reality.When mechatronic system applies to automation and robotics we can meet that easily.Mechatronic system apply to Servo-mechanics

Common type of servo provides position control.Servos are commonly electrical or partially electronic in nature, using an electric motor as the primary means of creating mechanical force.Other types of servos use hydraulics, pneumatics, or magnetic principles.Whatever type it is, it can be separate as feedback system, transducer system and control system.And all of it cannot be kept in functional order without mechatronic system engineering.3.Future challenges

Mechatronic products--products that blend mechanical, electrical and software technologies--have exploded far beyond such industries as high-tech, aerospace and consumer product goods.That means more and more product development teams that once may have been comprised of mechanical engineers and electrical engineers are now adding software to the mix.Multiple engineering disciplines are being challenged to work together in mechatronic product development, such as on this printed circuit board assembly created in PTC's Pro/Engineer.Additional challenges of mechatronic product development noted by PTC include MCAD changes not reaching electrical engineers quickly enough, ECAD designers working ahead of the mechanical engineer and failing to relay that information, and software development largely removed from the product development change management process.