第一篇:機(jī)械工程英語課文翻譯9-14
第九章 Lapping 研磨
Lapping is a finishing operation used on flat and cylindrical surfaces.The lap, shown in Fig.9.1a, is usually made of cast iron, copper, leather, or cloth.研磨是一種用于平面和圓柱面的精加工作業(yè)。研具,如圖9.1a所示,通常用鑄鐵、銅、皮革或布制成。
The abrasive particles are embedded in the lap, or they may be carried through slurry.Depending on the hardness of the workpiece, lapping pressures range from 7kPa to 140kPa(1 to 20 psi).研磨微粒嵌入研具內(nèi),或者可以通過液體攜帶。根據(jù)工件硬度,研磨壓力可在7kPa到140kPa(1到20psi)范圍中取。
Lapping has two main functions.Firstly, it produces a superior surface finish with all machining marks being removed from the surface.Secondly, it is used as a method of obtaining very close fits between mating parts such as pistons and cylinders.研磨有兩個(gè)主要作用。首先,它通過去除所有機(jī)加工痕跡能產(chǎn)生較好的表面光潔度。其次,它能用作獲得像活塞與氣缸之類配件間過盈配合的方法。
The lapped workpiece surface may look smooth but it is actually filled with microscopic peaks, valleys, scratches and pits.Few surfaces are perfectly flat.Lapping minimizes the surface irregularities, thereby increasing the available contact area.研磨后的工件表面可能看似平滑,其實(shí)布滿著微觀峰、谷、劃痕和凹陷。幾乎沒有表面是完全平整的。研磨使表面不規(guī)則最小化,因而增加了有效接觸面積。
The drawing in Fig.9.1a shows two surfaces.The upper one is how a surface might look before lapping and the lower one after lapping.Lapping removes the microscopic mountain tops and produces relatively flat plateaus.Entire microscopic mountain ranges may need to be ground down in order to increase the available contact area.圖9.1a上顯示了兩個(gè)表面。上面是研磨前表面可能的外觀模樣而下面則是研磨后的模樣。研磨去除了微觀峰頂從而產(chǎn)生相對(duì)平坦的平臺(tái)。整個(gè)微觀山脈范圍都需要磨去以增加有效接觸面積。
Production lapping on flat or cylindrical pieces is done on machines such as those shown in Fig.9.1b and 9.1c.Lapping is also done on curved surfaces, such as spherical objects and lenses, using specially shaped laps.研磨平面或圓柱面工件的生產(chǎn)過程是在如圖9.1b和9.1c那樣的機(jī)器上完成的。研磨也可采用特殊成型研具在諸如球形物體和透鏡之類的曲面上進(jìn)行。Polishing
拋光
Polishing is a process that produces a smooth, lustrous surface finish.Two basic mechanisms are involved in the polishing process:(a)fine-scale abrasive removal, and(b)softening and smearing of surface layers by frictional heating during polishing.拋光是生成平滑、有光澤表面光潔度的工藝。拋光工藝涉及兩種基本機(jī)理:(a)精細(xì)等級(jí)磨粒去除,和(b)在拋光中通過摩擦生熱軟化并抹光表面層。Electropolishing
Electropolishing is an electrochemical process similar to, but the reverse of, electroplating.The electropolishing process smoothes and streamlines the microscopic surface of a metal object.Mirror-like finishes can be obtained on metal surfaces by electropolishing.電解拋光
電解拋光是一種與電鍍相似的電化學(xué)工藝,但過程與電鍍正好相反。電解拋光工藝使金屬物體的微觀表面平滑和簡(jiǎn)單化。通過電解拋光能在金屬表面得到鏡面光潔度。
In electropolishing, the metal is removed ion by ion from the surface of the metal object being polished.Electrochemistry and the fundamental principles of electrolysis(Faraday’s Law)replace traditional mechanical finishing techniques.在電解拋光中,金屬是逐個(gè)離子地從被拋光金屬物體表面去除的。電化學(xué)和電解基本原理(Faraday定理)取代了傳統(tǒng)的機(jī)械精加工技術(shù)。
In basic terms, the object to be electropolished is immersed in an electrolyte and subjected to a direct electrical current.The object is maintained anodic, with the cathodic connection being made to a nearby metal conductor.用基本術(shù)語說,要電解拋光的物體被浸沒在電解液中并且通上直流電。該物體為陽極,陰極連接到附近的金屬導(dǎo)體上。
Smoothness of the metal surface is one of the primary and most advantageous effects of electropolishing.During the process, a film of varying thickness covers the surface of the metal.This film is thickest over micro depressions and thinnest over micro projections.金屬表面的平滑是電解拋光主要的和最有優(yōu)勢(shì)的效應(yīng)之一。在此過程中,一變化著厚度的膜覆蓋在金屬表面上。該膜在微觀凹陷處最厚而在微觀凸出處最薄。
Electrical resistance is at a minimum wherever the film is thinnest, resulting in the greatest rate of metallic dissolution.Electropolishing selectively removes microscopic high points or “peaks” faster than the rate of attack on the corresponding micro-depressions or “valleys”.電阻在膜最薄處最小,導(dǎo)致最大金屬分解率。電解拋光選擇性地去除微觀高點(diǎn)或“峰” 快于對(duì)相應(yīng)微觀凹陷處或“谷”的侵蝕速率。
Stock is removed as metallic salt.Metal removal under certain circumstances is controllable and can be held to 0.0001 to 0.0025 mm.原材料以金屬鹽的形式被去除。在特定環(huán)境下金屬的去除是可控的并且保持在0.0001 到0.0025mm范圍內(nèi)。
Chemical Mechanical Polishing
Chemical mechanical polishing is becoming an increasingly important step in the fabrication of multi-level integrated circuits.Chemical mechanical polishing refers to polishing by abundant slurry that interacts both chemically and mechanically with the surface being polished.化學(xué)機(jī)械拋光
化學(xué)機(jī)械拋光正在多層集成電路制造領(lǐng)域成為日益重要的步驟?;瘜W(xué)機(jī)械拋光是指大量拋光液與被拋光表面產(chǎn)生化學(xué)和機(jī)械作用的拋光。
During the chemical mechanical polishing process, a rotating wafer is pressed face down onto a rotating, resilient polishing pad while polishing slurry containing abrasive particles and chemical reagents flows in between the wafer and the pad.在化學(xué)機(jī)械拋光過程中,旋轉(zhuǎn)晶片面向下壓在旋轉(zhuǎn)、有回彈力的拋光襯墊上,而同時(shí)含有研磨微粒和化學(xué)反應(yīng)物的拋光液流過晶片與襯墊之間。
The combined action of polishing pad, abrasive particles and chemical reagents results in material removal and polishing of the wafer surface.Chemical mechanical polishing creates flat, damage-free on a variety of brittle materials and it is used extensively on silicon wafers in the manufacture of integrated circuits.拋光襯墊、研磨微粒和化學(xué)反應(yīng)物的共同作用導(dǎo)致晶片表面的材料去除并拋光?;瘜W(xué)機(jī)械拋光可使多種易碎材料平整且不受損害,因此在集成電路制造中被廣泛地用在硅晶片上。
Chemical mechanical polishing is a complicated multiphase process.It mainly includes the following two dynamics.First, the active component in polishing slurry reacts with the atoms of the wafer, and the process is chemical reaction step with oxidation-reductive reaction.化學(xué)機(jī)械拋光是一種復(fù)雜的多相工藝。它主要包括下列兩個(gè)動(dòng)態(tài)過程:第一,拋光液中活性成分與晶片的原子發(fā)生反應(yīng),這是帶有氧化-還原反應(yīng)的化學(xué)反應(yīng)步驟。
The second step is the process of desorption, that is to say, the resultants gradually separate from the wafer surface and new surface is exposed to polishing slurry.If chemical reactive rate is smaller, the total removal rate of the wafer is also small;furthermore, the surface degree of finish is not good.第二步是解吸附過程,即反應(yīng)產(chǎn)物逐漸從晶片表面分離并將新表面暴露給拋光液。如果化學(xué)反應(yīng)速率較小,晶片的總?cè)コ室草^小,而且表面光潔程度不夠好。
On the contrary, even if chemical reaction is very rapid, but desorption is very slow, the total removal rate is not good.Because resultants connot separate from the wafer surface, the active component in the polishing slurry cannot expose and react with the atoms on the new surface, which holds up chemical reaction.與之相反,即使化學(xué)反應(yīng)很快,但解吸附很慢,則總?cè)コ室膊粔蚝?。因?yàn)榉磻?yīng)產(chǎn)物不能從晶片表面分離,拋光液中活性成分就不能暴露并與新表面上的原子起反應(yīng),這會(huì)抑制化學(xué)反應(yīng)。
The balance and compositive effects of two steps decide the total removal rate and its surface degree of finish.這兩個(gè)步驟的平衡與合成效應(yīng)決定了總?cè)コ屎捅砻婀鉂嵆潭取?/p>
第十章 Surface Engineering 表面處理
The processes of surface engineering, or surface treatments, tailor the surfaces of engineering materials to:(1)control friction and wear,(2)improve corrosion resistance,(3)change physical property, e.g., conductivity, resistivity, and reflection,(4)alter dimension,(5)vary appearance, e.g., color and roughness,(6)reduce cost.進(jìn)行表面工程或表面處理的目的是:(1)控制摩擦和磨損,(2)改善抗腐蝕性,(3)改變物理性能,例如,傳導(dǎo)率、電阻系數(shù)和反射率,(4)修改尺寸,(5)變更外觀,例如顏色和粗糙程度,(6)降低成本。
Common surface treatments can be divided into two major categories: treatments that cover the surfaces and treatments that alter the surfaces.通常的表面處理可以分為兩個(gè)主要類型:覆蓋表面的處理和改變表面的處理。Covering the Surface覆蓋表面
The treatments that cover the surfaces include organic coatings and inorganic coatings.覆蓋表面的處理包括有機(jī)涂層和無機(jī)涂層。
The inorganic coatings perform electroplatings, conversion coatings, thermal sprayings, hot dippings, furnace fusings, or coat thin films, glass, ceramics on the surfaces of the materials.無機(jī)涂層有電鍍、轉(zhuǎn)化層、熱噴涂、熱浸漬、熔爐熔融、或在材料表面涂上薄膜、玻璃、陶瓷。
Electroplating is an electrochemical process by which metal is deposited on a substrate by passing a current through the bath.電鍍是一種在電鍍槽通上電流使金屬沉淀在基體上的電化學(xué)過程。
Usually there is an anode(positively charged electrode), which is the source of the material to be deposited;the electrochemistry which is the medium through which metal ions are exchanged and transferred to the substrate to be coated;and a cathode(negatively charged electrode)which is the substrate to be coated.通常有一個(gè)陽極(正電極),是要沉淀材料的來源;電化學(xué)反應(yīng)是使金屬離子交換并遷移到要覆蓋基體上的中間過程;以及一個(gè)陰極(負(fù)電極),即要覆蓋的基體。
Plating is done in a plating bath which is usually a non-metallic tank(usually plastic).The tank is filled with electrolyte which has the metal, to be plated, in ionic form.電鍍?cè)谕ǔ榉墙饘偃萜?一般是塑料)的電鍍槽中進(jìn)行。該容器裝滿了含有離子態(tài)被鍍金屬的電解液。
The anode is connected to the positive terminal of the power supply.The anode is usually the metal to be plated(assuming that the metal will corrode in the electrolyte).For ease of operation, the metal is in the form of nuggets and placed in an inert metal basket made out non-corroding metal(such as titanium or stainless steel).陽極與電源正極相連。陽極通常為被鍍金屬(假定該金屬能在電解液中腐蝕)。為了操作容易,該金屬呈固體小塊形式并置于由抗腐蝕金屬(如鈦或不銹鋼)制成的惰性金屬筐內(nèi)。
The cathode is the workpiece, the substrate to be plated.This is connected to the negative terminal of the power supply.The power supply is well regulated to minimize ripples as well to deliver a steady predictable current, under varying loads such as those found in plating tanks.陰極是工件,即要鍍的基體,連接到電源的負(fù)極。很好地調(diào)節(jié)電源使波動(dòng)最小化并在載荷變化情況(如同電鍍?nèi)萜髦锌吹降哪菢?下提供穩(wěn)定的可預(yù)知電流。
As the current is applied, positive metal ions from the solution are attracted to the negatively charged cathode and deposit on the cathode.As a replenishment for these deposited ions, the metal from the anode is dissolved and goes into the solution and balances the ionic potential.一旦通上電流,來自溶液的正的金屬離子被吸引到帶負(fù)電的陰極并沉淀在其上。作為這些沉淀離子的補(bǔ)充,來自陽極的金屬被溶解并進(jìn)入溶液平衡離子勢(shì)能。
Thermal spraying process.Thermal spraying metal coatings are depositions of metal which has been melted immediately prior to projection onto the substrate.The metals used and the application systems used vary but most applications result in thin coatings applied to surfaces requiring improvement to their corrosion or abrasion resistance properties.熱噴涂工藝:熱噴涂金屬涂層是金屬熔化后立即投射到基體上形成的金屬沉積層。所用的金屬和應(yīng)用系統(tǒng)都可以變化,但大多數(shù)應(yīng)用都是在要求改善抗腐蝕或耐磨性能的表面涂上薄層。
Thermal spray is a generic term for a broad class of related processes in which molten droplets of metals, ceramics, glasses, and/or polymers are sprayed onto a surface to produce a
coating, to form a free-standing near-net-shape, or to create an engineered material with unique properties.熱噴涂是用于很大一類相關(guān)工藝的一個(gè)通用術(shù)語,噴涂到表面產(chǎn)生涂層的熔化小滴可以是金屬、陶瓷、玻璃和/或聚合物,形成獨(dú)立的近似純形或產(chǎn)生具有獨(dú)特性能的設(shè)計(jì)材料。
In principle, any material with a stable molten phase can be thermally sprayed, and a wide range of pure and composite materials are routinely sprayed for both research and industrial applications.Deposition rates are very high in comparison to alternative coating technologies.大體上,有穩(wěn)定熔化狀態(tài)的任何材料都可以熱噴涂,范圍寬闊的純凈和合成材料一般都能噴涂用于研究及工業(yè)目的。其沉積率與可供選擇的涂層技術(shù)比較是很高的。
Deposit thickness of 0.1 to 1mm is common, and thickness greater than 1cm can be achieved with some materials.沉淀厚度普遍為0.1到1mm,對(duì)某些材料則沉淀厚度可以達(dá)到1cm以上。
The process for application of thermal spray metal is relatively simple and consists of the following stages.(1)Melting the metal at the gun.(2)Spraying the liquid metal onto the prepared substrate by means of compressed air.熱噴涂金屬的應(yīng)用工藝相對(duì)簡(jiǎn)單并由下列階段組成:(1)在噴槍內(nèi)熔化金屬。
(2)通過壓縮空氣將液態(tài)金屬噴涂在準(zhǔn)備好的基體上。(3)Molten particles are projected onto the cleaned substrate.There are two main types of wire application available today namely arc spray and gas spray.(3)熔化微粒投射在清潔過的基體上。
現(xiàn)在有兩種主要的金屬絲應(yīng)用類型可選用,也就是電弧噴涂和氣體噴涂。
ARC—A pair of wires are electrically energized so that an arc is struck across the tips when brought together through a pistol.Compressed air is blown across the arc to atomise and propel the autofed metal wire particles onto the prepared workpiece.電弧噴涂—當(dāng)一對(duì)金屬絲通過手持噴槍連到一起時(shí),通上電橫過其末端劃燃電弧。壓縮空氣吹過電弧使其霧化并驅(qū)使自動(dòng)送料金屬絲微粒到準(zhǔn)備好的工件上。
GAS—In combustion flame spraying the continuously moving wire is passed through a pistol, melted by a conical jet of burning gas.The molten wire tip enters the cone, atomises and is propelled onto the substrate.氣體噴涂—連續(xù)移動(dòng)的金屬絲在燃燒火焰噴射中通過手持噴槍,并被燃燒氣體的錐形噴嘴所熔化。熔化后的金屬絲頂端進(jìn)入錐體霧化并驅(qū)使其到基體上。
Thin-Film Coatings.Physical Vapor Deposition(PVD)and Chemical Vapor Deposition(CVD)are two most common types of thin-film coating methods.薄膜涂層:物理蒸發(fā)沉淀(PVD)和化學(xué)蒸發(fā)沉淀(CVD)是兩種最常見薄膜涂層方法的類型。
PVD coatings involve atom-by-atom, molecule-by-molecule, or ion deposition of various materials on solid substrates in vacuum systems.物理蒸發(fā)沉淀涂層涉及到在真空裝置內(nèi)各種各樣的材料原子緊靠原子、分子緊靠分子或離子沉淀于固態(tài)基體上。
Thermal evaporation uses the atomic cloud formed by the evaporation of the coating metal
in a vacuum environment to coat all the surfaces in the line of sight between the substrate and the target.It is often used in producing thin, 0.5μm, decorative shiny coatings on plastic parts.熱蒸發(fā)利用涂層金屬在真空環(huán)境中蒸發(fā)形成的微粒子霧將基體和靶材之間可見范圍內(nèi)所有表面覆蓋。在塑料零件上生成較薄(0.5μm)的、裝飾性的、有光澤的涂層時(shí)常常用到它。
The thin coating, however, is fragile and not good for wear applications.The thermal evaporation process can also coat a very thick, 1mm, layer of heat-resistant materials, such as MCrAIY—a metal, chromium, aluminum, and yttrium alloys, on jet engine parts.然而,這種薄涂層是易碎的并不適合用于磨損場(chǎng)合。熱蒸發(fā)工藝也能在噴氣發(fā)動(dòng)機(jī)零件上覆蓋很厚(1mm)的耐熱材料涂層,例如MCrAIY—一種金屬、鉻、鋁和釔合金。
Sputtering applies high-technology coatings such as ceramics, metal alloys, organic and inorganic compounds by connecting the workpiece and the substance to a high-voltage DC power supply in an argon vacuum system.反應(yīng)濺射法通過在氬真空設(shè)備中連接工件和具有特定成分的材料到高壓直流電來應(yīng)用諸如陶瓷、金屬合金、有機(jī)和無機(jī)化合物之類的高技術(shù)涂層。
The plasma is established between the substrate(workpiece)and the target(donor)and transposes the sputtered off target atoms to the surface of the substrate.等離子區(qū)形成于基體(工件)和靶材(原料物質(zhì))之間并將被濺射的靶材原子轉(zhuǎn)移到基體的表面上。
When the substrate is non-conductive, e.g., polymer, a radio-frequency(RF)sputtering is used instead.Sputtering can produce thin, less than 3μm(120μin), hard thin-film coatings, e.g., titanium nitride(TIN)which is harder than the hardest metal.如果基體不導(dǎo)電,例如聚合物,則采用射頻(RF)濺射代替。反應(yīng)濺射法可以生成較薄(小于3μm(120μin))的、堅(jiān)硬薄膜涂層,像比最硬金屬還硬的氮化鈦(TIN)。
Sputtering is now widely applied on cutting tools, forming tools, injection molding tools, and common tools such as punches and dies, to increase wear resistance and service life.現(xiàn)在反應(yīng)濺射法已被廣泛應(yīng)用于切削刀具、成型工具、注射模具和諸如沖頭和沖模之類的通用器具,以增強(qiáng)其耐磨性和使用壽命。
CVD is capable of producing thick, dense, ductile, and good adhesive coatings on metals and non-metals such as glass and plastic.Contrasting to the PVD coating in the “l(fā)ine of sight”, the CVD can coat all surfaces of the substrate.化學(xué)蒸發(fā)沉淀能在金屬和像玻璃和塑料之類的非金屬上生成較厚的、致密的、有延伸性的和帶良好粘性的涂層。與物理蒸發(fā)沉淀在“可見范圍”對(duì)比,化學(xué)蒸發(fā)沉淀能將基體的所有表面都覆蓋。
Conventional CVD coating process requires a metal compound that will volatilize at a fairly low temperature and decompose to a metal when it contacts with the substrate at higher temperature.常規(guī)的化學(xué)蒸發(fā)沉淀涂層工藝需要一種容易在相當(dāng)?shù)蜏囟认聯(lián)]發(fā)并且在較高溫度下與基體接觸時(shí)能分解成純金屬的金屬化合物。
The most well known example of CVD is the nickel carbonyl(NiCO4)coating as thick as 2.5mm(0.1in.)on glass windows and containers to make them explosion or shatter resistant.最為人熟知的化學(xué)蒸發(fā)沉淀例子是在玻璃窗和容器上鍍厚為2.5mm(0.1in.)的羰基鎳(NiCO4)涂層使它們能抵抗爆裂或破碎。
Diamond CVD coating process is introduced to increase the surface hardness of cutting
tools.However, the process is done at the temperatures higher than 700℃(1300℉)which will soften most tool steel.為增加切削刀具表面硬度引入了鉆石化學(xué)蒸發(fā)沉淀涂層工藝??墒谴斯に囈诟哂?00℃(1300℉)的溫度下才能實(shí)現(xiàn),這溫度會(huì)軟化大多數(shù)工具鋼。
Thus, the application of diamond CVD is limited to materials which will not soften at this temperature such as cemented carbides.因而鉆石化學(xué)蒸發(fā)沉淀的應(yīng)用受到材料限制,要求材料在此溫度下不軟化例如硬質(zhì)合金。
Plasma-Assisted CVD coating process can be performed at lower temperature than diamond CVD coatings.This CVD process is used to apply diamond coatings or silicon carbide barrier coatings on plastic films and semiconductors, including the state of the art 0.25μm semiconductors.等離子體輔助化學(xué)蒸發(fā)沉淀涂層工藝可以在比鉆石化學(xué)蒸發(fā)沉淀涂層低的溫度下操作。這種化學(xué)蒸發(fā)沉淀用于在塑料膜和半導(dǎo)體(包括人工0.25μm半導(dǎo)體的情況)上覆蓋鉆石涂層或碳化硅隔離涂層。Altering the Surfaces改變表面
The treatments that alter the surfaces include hardening treatments, high-energy processes and special treatments.改變表面的處理包括淬火處理、高能加工和特殊處理。
High-energy processes are relatively new surface treatment methods.They can alter the properties of surfaces without changing the dimension of the surface.Common high-energy processes, including electron beam treatment, ion implantation, and laser beam treatment, are briefly discussed as follows:
高能加工是相對(duì)較新的表面處理方法。它們能在不改變表面尺寸的情況下改變表面性能。通用的高能加工包括電子束處理、離子注入和激光束處理簡(jiǎn)要討論如下:
Electron beam treatment.Electron beam treatment alters the surface properties by rapid heating—using electron beam and rapid cooling—in the order of 106℃/see in a very shallow region, 100μm, near the surface.This technique can also be used in hardfacing to produce “surface alloys”.電子束處理:電子束處理在靠近表面很淺(100μm)的區(qū)域通過用電子束快速加熱并以106℃/秒等級(jí)快速冷卻來改變表面性能。這種技術(shù)也被用于表面硬化產(chǎn)生“表面合金”。
Ion implantation.Ion implantation uses electron beam or plasma to impinge gas atoms to ions with sufficient energy, and embed these ions into atomic lattice of the substrate, accelerated by magnetic coils in a vacuum chamber.The mismatch between ion implant and the surface of a metal creates atomic defects that harden the surface.離子注入:離子注入采用電子束或等離子體通過真空室內(nèi)磁性線圈加速以足夠的能量將氣體原子撞擊為離子,并把這些離子嵌入基體的原子點(diǎn)陣中。離子注入和金屬表面之間的錯(cuò)配產(chǎn)生了硬化表面的原子瑕疵。
Laser beam treatment.Similar to electron beam treatment, laser beam treatment alters the surface properties by rapid heating and rapid cooling in a very shallow region near the surface.It can also be used in hardfacing to produce “surface alloys”.激光束處理:與電子束處理類似,激光束處理通過在靠近表面很淺的區(qū)域快速加熱和快速冷卻來改變表面性能。它也可以用于表面硬化產(chǎn)生“表面合金”。
The results of high-energy processes are not well known or very well controlled.But the
preliminary results look promising.Further development is needed in high-energy processes, especially in implant dosages and treatment methods.高能加工的結(jié)果不能充分地了解或很好地控制。但初步結(jié)果看來是有前途的。高能加工需要進(jìn)一步的開發(fā),特別是注入劑量和處理方法。
第十一章 Lathe 車床
The Lathe and Its Construction車床及其結(jié)構(gòu)
A lathe is a machine tool used primarily for producing surfaces of revolution and flat edges.車床是主要用于生成旋轉(zhuǎn)表面和平整邊緣的機(jī)床。
Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows: 根據(jù)它們的使用目的、結(jié)構(gòu)、能同時(shí)被安裝刀具的數(shù)量和自動(dòng)化的程度,車床—或更確切地說是車床類的機(jī)床,可以被分成以下幾類:
(1)Engine lathes(2)Toolroom lathes(3)Turret lathes(4)Vertical turning and boring mills(5)Automatic lathes(6)Special-purpose lathes(1)普通車床(2)萬能車床(3)轉(zhuǎn)塔車床(4)立式車床(5)自動(dòng)車床(6)特殊車床
In spite of that diversity of lathe-type machine tools, they all have common features with respect to construction and principle of operation.These features can best be illustrated by considering the commonly used representative type, the engine lathe.Following is a description of each of the main elements of an engine lathe, which is shown in Fig.11.1.雖然車床類的機(jī)床多種多樣,但它們?cè)诮Y(jié)構(gòu)和操作原理上具有共同特性。這些特性可以通過普通車床這一最常用的代表性類型來最好地說明。下面是關(guān)于圖11.1所示普通車床的主要部分的描述。
Lathe bed.The lathe bed is the main frame, involving a horizontal beam on two vertical supports.It is usually made of grey or nodular cast iron to damp vibrations and is made by casting.車床床身:車床床身是包含了在兩個(gè)垂直支柱上水平橫梁的主骨架。為減振它一般由灰鑄鐵或球墨鑄鐵鑄造而成。
It has guideways to allow the carriage to slide easily lengthwise.The height of the lathe bed should be appropriate to enable the technician to do his or her job easily and comfortably.它上面有能讓大拖板輕易縱向滑動(dòng)的導(dǎo)軌。車床床身的高度應(yīng)適當(dāng)以讓技師容易而舒適地工作。
Headstock.The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guideways(the slide surface of the bed).The spindle is driven through the gearbox, which is housed within the headstock.主軸箱:主軸箱固定在車床床身的左側(cè),它包括軸線平行于導(dǎo)軌的主軸。主軸通過裝在主軸箱內(nèi)的齒輪箱驅(qū)動(dòng)。
The function of the gearbox is to provide a number of different spindle speeds(usually 6 up to 18 speeds).Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional ,electrical ,or hydraulic drives.齒輪箱的功能是給主軸提供若干不同的速度(通常是6到18速)。有些現(xiàn)代車床具有采用摩擦、電力或液壓驅(qū)動(dòng)的無級(jí)調(diào)速主軸箱。
The spindle is always hollow, i.e., it has a through hole extending lengthwise.Bar stocks can be fed through that hole if continuous production is adopted.主軸往往是中空的,即縱向有一通孔。如果采取連續(xù)生產(chǎn),棒料能通過此孔進(jìn)給。Also, that hole has a tapered surface to allow mounting a plain lathe center.The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the like.同時(shí),此孔為錐形表面可以安裝普通車床頂尖。主軸外表面是螺紋可以安裝卡盤、花盤或類似的裝置。
Tailstock.The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill.The lower base is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the workpiece.尾架:尾架總成基本包括三部分,底座、尾架體和套筒軸。底座是能在車床床身上沿導(dǎo)軌滑動(dòng)的鑄件,它有一定位裝置能讓整個(gè)尾架根據(jù)工件長度鎖定在任何需要位置。The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock.The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the intermediate part as required.尾架體為一能橫向運(yùn)動(dòng)的鑄件,它可以調(diào)整尾架軸線與主軸箱軸線成一直線。第三部分,套筒軸是一淬硬鋼管,它能根據(jù)需要在尾架體中縱向進(jìn)出移動(dòng)。
This is achieved through the use of a handwheel and a screw, around which a nut fixed to the quill is engaged.The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars.The quill can be locked at any point along its travel path by means of a clamping device.這通過使用手輪和螺桿來達(dá)到,與螺桿嚙合的是一固接在套筒軸上的螺母。套筒軸開口端的孔是錐形的,能安裝車床頂尖或諸如麻花鉆和鏜桿之類的工具。套筒軸通過定位裝置能沿著它的移動(dòng)路徑被鎖定在任何點(diǎn)。
The carriage.The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds.It is actually an H-shaped block that slides on the lathe
bed between the headstock and tailstock while being guided by the V-shaped guideways of the bed.大拖板:大拖板的主要功能是安裝刀具和產(chǎn)生縱向和/或橫向進(jìn)給。它實(shí)際上是一由車床床身V形導(dǎo)軌引導(dǎo)的、能在車床床身主軸箱和尾架之間滑動(dòng)的H形滑塊。
The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw.大拖板能手動(dòng)或者通過溜板箱和光桿(進(jìn)給桿)或絲桿(引導(dǎo)螺桿)機(jī)動(dòng)。
When cutting screw threads, power is provided to the gearbox of the apron by the lead screw.In all other turning operations, it is the feed rod that drives the carriage.The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron.在切削螺旋時(shí),動(dòng)力通過絲桿提供給溜板箱上的齒輪箱。在其余車削作業(yè)中,都由光桿驅(qū)動(dòng)大拖板。絲桿穿過一對(duì)固定在溜板箱后部的剖分螺母。
When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage, along the bed.When the lever is disengaged, the half nuts are released and the carriage stops.當(dāng)開動(dòng)特定操作桿時(shí),剖分螺母夾在一起作為單個(gè)螺母與旋轉(zhuǎn)的絲桿嚙合,并帶動(dòng)拖板沿著床身提供進(jìn)給。當(dāng)操作桿脫離時(shí),剖分螺母釋放同時(shí)大拖板停止運(yùn)動(dòng)。
On the other hand, when the feed rod is used, it supplies power to the apron through a worm gear.The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole length.另一方面,當(dāng)使用光桿時(shí)則通過蝸輪給溜板箱提供動(dòng)力。蝸輪用鍵連接在光桿上,并與溜板箱一起沿光桿運(yùn)動(dòng),光桿全長范圍開有鍵槽。
A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears.It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers.現(xiàn)代車床一般在主軸箱下裝備快速變換齒輪箱,通過一系列齒輪由主軸驅(qū)動(dòng)。它與光桿和絲桿連接,能容易并快速地通過簡(jiǎn)單轉(zhuǎn)換適當(dāng)?shù)牟僮鳁U選擇各種進(jìn)給。
The quick-change gearbox is employed in plain turning, facing and thread cutting operations.Since that gearbox is linked to the spindle, the distance that the apron(and the cuttingtool)travels for each revolution of the spindle can be controlled and is referred to as the feed.快速變換齒輪箱可用于普通車削、端面切削和螺旋切削作業(yè)中。由于這種齒輪箱與主軸相連,主軸每轉(zhuǎn)一圈溜板箱(和切削刀具)運(yùn)動(dòng)的距離能被控制,這距離就可以被認(rèn)為是進(jìn)給。
Lathe Cutting Tools車床切削刀具
The shape and geometry of the lathe tools depend upon the purpose for which they are employed.車床刀具的形狀和幾何參數(shù)取決于它們的使用目的。
Turning tools can be classified into two main groups, namely, external cutting tools and internal cutting tools.Each of these two groups include the following types of tools: 車削刀具可以分為兩個(gè)主要組別,即外部切削刀具和內(nèi)部切削刀具。這兩組中的每一組都包括以下類型刀具:
Turning tools.Turning tools can be either finishing or rough turning tools.Rough turning tools have small nose radii and are employed when deep cuts are made.車削刀具:車削刀具可以是精車刀具或粗車刀具。粗車刀具刀尖半徑較小,用于深
切削。
On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut.Rough turning tools can be right-hand or left-hand types, depending upon the direction of feed.They can have straight, bent, or offset shanks.而精車刀具刀尖半徑較大,用于通過微量進(jìn)刀深度來獲得具有較好表面光潔度的最終所需尺寸。粗車刀具按其進(jìn)給方向可以是右手型的或是左手型的。它們可以有直的、彎的或偏置的刀桿。
Facing tools.Facing tools are employed in facing operations for machining plane side or end surfaces.There are tools for machining left-hand-side surfaces and tools for right-hand-side surfaces.Those side surfaces are generated through the use of the cross feed, contrary to turning operations, where the usual longitudinal feed is used.端面刀具:端面刀具用在端面作業(yè)中加工平板側(cè)面或端部表面,也有加工左右側(cè)表面之分。與一般采用縱向進(jìn)給的車削作業(yè)相反,那些側(cè)表面通過采用橫向進(jìn)給產(chǎn)生。
Cutoff tools.Cutoff tools, which are sometimes called parting tools, serve to separate the workpiece into parts and/or machine external annular grooves.切斷刀具:切斷刀具,有時(shí)也稱為分割刀具,用于將工件分割成若干部分和/或加工外部環(huán)形槽。
Thread-cutting tools.Thread-cutting tools have either triangular, square, or trapezoidal cutting edges, depending upon the cross section of the desired thread.Also, the plane angles of these tools must always be identical to those of the thread forms.螺紋切削刀具:螺紋切削刀具根據(jù)所需螺紋的橫截面,有三角形的、矩形的或梯形的切削刃。同時(shí),這些刀具的平面角必須始終與螺紋形狀的平面角保持一致。
Thread-cutting tools have straight shanks for external thread cutting and are of the bent-shank type when cutting internal threads.車外螺紋的螺紋切削刀具為直刀桿,而車內(nèi)螺紋的螺紋切削刀具則是彎刀桿。
Form tools.Form tools have edges especially manufactured to take a certain form, which is opposite to the desired shape of the machined workpiece.成形刀具:成形刀具有專門制成特定形狀的刀刃,這種刀刃形狀與被加工工件所需外形正好相反。
An HSS tool is usually made in the form of a single piece, contrary to cemented carbides or ceramic, which are made in the form of tips.The latter are brazed or mechanically fastened to steel shanks.
高速鋼刀具通常以單件形式制造,而硬質(zhì)合金或陶瓷刀具則以刀尖形式制造。后者用銅焊或機(jī)械方法固定于鋼質(zhì)刀桿上。
Fig.11.2 indicates an arrangement of this latter type, which includes the carbide tip, the chip breaker, the pad, the clamping screw(with a washer and a nut), and the shank.圖11.2所示為機(jī)械式固定布置方式,它包括了硬質(zhì)合金刀尖、斷屑槽、襯墊、卡裝螺桿(帶有墊圈和螺母)及刀桿。
As the name suggests, the function of the chip breaker is to break long chips every now and then, thus preventing the formation of very long twisted ribbons that may cause problems during the machining operation.顧名思義,斷屑槽的功能就是不時(shí)地折斷長切屑,以防形成很長的可能會(huì)在機(jī)加工操作中引起問題的纏繞切屑條。
The carbide tips(or ceramic tips)can have different shapes, depending upon the machining operations for which they are to be employed.The tips can either be solid or with a central through hole, depending on whether brazing or mechanical clamping is employed for mounting the tip on the shank.硬質(zhì)合金刀尖(或陶瓷刀尖)根據(jù)采用它們的機(jī)加工操作,可以有不同的形狀。根據(jù)將刀尖裝配在刀桿上是通過用銅焊還是機(jī)械卡裝,刀尖可以是實(shí)心的或是帶有中心通孔的。Lathe Operations車床操作
In the following section, we discuss the various machining operations that can be performed on a conventional engine lathe.在下面這節(jié)中,要討論的是能在傳統(tǒng)普通車床上進(jìn)行的各種機(jī)加工作業(yè)。
It must be borne in mind, however, that modern computerized numerically controlled lathes have more capabilities and can do other operations, such as contouring, for example.Following are conventional lathe operations.然而,必須記住現(xiàn)代計(jì)算機(jī)數(shù)控車床具有更多的功能并且可以進(jìn)行其它操作,例如仿型。下面是傳統(tǒng)車床的操作。
Cylindrical turning.Cylindrical turning is the simplest and the most common of all lathe operations.A single full turn of the workpiece generates a circle whose center falls on the lathe axis;this motion is then reproduced numerous times as a result of the axial feed motion of the tool.圓柱面車削:圓柱面車削是所有車床操作中最簡(jiǎn)單也是最普通的。工件旋轉(zhuǎn)一整圈產(chǎn)生一個(gè)圓心落在車床主軸上的圓;由于刀具的軸向進(jìn)給運(yùn)動(dòng)這種動(dòng)作重復(fù)許多次。
The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed.Consequently, the machined surface is always cylindrical.所以,由此產(chǎn)生的機(jī)加工痕跡是一條具有很小節(jié)距的螺旋線,該節(jié)距等于進(jìn)給。因此機(jī)加工表面始終是圓柱形的。
The axial feed is provided by the carriage or the compound rest, either manually or automatically, whereas the depth of cut is controlled by the cross slide.軸向進(jìn)給通過大拖板或復(fù)式刀架手動(dòng)或自動(dòng)提供,然而切削深度則由橫向滑板控制。In roughing cuts, it is recommended that large depths of cuts(up to 0.25in.or 6mm, depending upon the workpiece material)and smaller feeds would be used.On the other hand, very fine feeds, smaller depths of cut(less than 0.05in, or 0.4mm), and high cutting speeds are preferred for finishing cuts.粗車中,推薦使用較大切削深度(根據(jù)工件材料可達(dá)0.25英寸或6毫米)和較小進(jìn)給。另一方面,精車則最好采用很小的進(jìn)給、較小的切削深度(小于0.05英寸或0.4毫米)和較高的切削速度。
Facing.The result of a facing operation is a flat surface that is either the whole end surface of the workpiece or an annular intermediate surface like a shoulder.During a facing operation, feed is provided by the cross slide, whereas the depth of cut is controlled by the carriage or compound rest.端面車削:端面車削操作的結(jié)果是將工件整個(gè)端部表面或者像軸肩之類的中間環(huán)形表面加工平整。在端面車削操作中,進(jìn)給由橫向滑板提供,而切削深度則通過大拖板或復(fù)式刀架控制。
Facing can be carried out either from the periphery inward or from the center of the workpiece outward.It is obvious that the machining marks in both cases take the form of a spiral.端面車削既可以從外表面向內(nèi)切削也可以從工件中心往外切削。很明顯在這兩種情況下機(jī)加工痕跡都是螺線形式。
Usually, it is preferred to clamp the carriage during a facing operation, since the cutting force tends to push the tool(and, of course, the whole carriage)away from the workpiece.In most facing operations, the workpiece is held in a chuck or on a face plate.通常在端面車削作業(yè)時(shí)習(xí)慣于采用夾住大拖板,這是因?yàn)榍邢髁A向于將刀具(當(dāng)然包括整個(gè)大拖板)推離工件。在大多數(shù)端面車削作業(yè)中,工件被支撐在卡盤或花盤上。
Groove cutting.In cut-off and groove-cutting operations, only cross feed of the tool is employed.The cut-off and grooving tools, which were previously discussed, are employed.開槽:在切斷和開槽操作中,刀具只有橫向進(jìn)給。要采用前面已經(jīng)討論過的切斷和開槽刀具。
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.鏜孔和內(nèi)部車削:鏜孔和內(nèi)部車削通過鏜桿或合適的內(nèi)部切削刀具在內(nèi)表面進(jìn)行。如果初始工件是實(shí)心的,則必須首先進(jìn)行鉆孔作業(yè)。鉆孔刀具安裝在尾架上,然后對(duì)著工件進(jìn)給。
Taper turning.Taper turning is achieved by driving the tool in a direction that is not parallel to the lathe axis but inclined to it with an angle that is equal to the desired angle of the taper.Following are the different methods used in taper-turning practice:
錐面車削:錐面車削通過沿著與車床主軸不平行而傾斜成一個(gè)等于錐面所需角度的方向進(jìn)刀來實(shí)現(xiàn)。下面是在實(shí)際錐面車削中采用的不同方法:
(1)Rotating the disc of the compound rest with an angle equal to half the apex angle of the cone.Feed is manually provided by cranking the handle of the compound rest.This method is recommended for taper turning of external and internal surfaces when the taper angle is relatively large.(1)將復(fù)式刀架盤旋轉(zhuǎn)一個(gè)等于圓錐體頂角一半的角度。通過搖動(dòng)復(fù)式刀架操縱柄手動(dòng)提供進(jìn)給。當(dāng)錐角相對(duì)較大時(shí)切削外錐面和內(nèi)錐面推薦使用這種方法。
(2)Employing special form tools for external, very short, conical surfaces.The width of the workpiece must be slightly smaller than that of the tool, and the workpiece is usually held in a chuck or clamped on a face plate.In this case, only the cross feed is used during the machining process and the carriage is clamped to the machine bed.(2)對(duì)很短的外錐面采用特殊的成型刀具。工件的寬度必須略小于刀具的寬度,并且工件通常由卡盤支撐或夾緊在花盤上。在這種情況下,機(jī)加工作業(yè)時(shí)只有橫向進(jìn)給而大拖板則夾緊在床身上。
(3)Offsetting the tailstock center.This method is employed for external taper turning of long workpieces that are required to have small taper angles(less than 8°).The workpiece is mounted between the two centers;then the tailstock center is shifted a distance S in the direction normal to the lathe axis.(3)偏移尾架頂尖。對(duì)需要較小錐角(小于8°)的較長工件外錐面車削采用這種方法。工件安裝于兩頂尖之間;然后將尾架頂尖朝垂直于車床主軸方向移動(dòng)一距離S。
(4)Using the taper-turning attachment.This method is used for turning very long workpieces, when the length is larger than the whole stroke of the compound rest.The procedure followed in
such cases involves complete disengagement of the cross slide from the carriage, which is then guided by the taper-turning attachment.(4)采用錐面車削附加裝置。這種方法用于車削很長的工件,其長度大于復(fù)式刀架的整個(gè)行程。在這種場(chǎng)合下要遵循的步驟是將橫向滑板完全脫離大拖板,然后通過錐面車削附加裝置進(jìn)行引導(dǎo)。
During this process, the automatic axial feed can be used as usual.This method is recommended for very long workpieces with a small cone angle, i.e., 8°through 10°.在此作業(yè)中,能照常使用自動(dòng)軸向進(jìn)給。對(duì)具有較小錐角(即8°到10°)的很長工件推薦采用這種方法。
Thread cutting.When performing thread cutting, the axial feed must be kept at a constant rate, which is dependent upon the rotational speed(rpm)of the workpiece.The relationship between both is determined primarily by the desired pitch of the thread to be cut.螺紋切削:在螺紋切削作業(yè)時(shí),軸向進(jìn)給必須保持恒定速率,這取決于工件的轉(zhuǎn)速(rpm)。兩者之間的關(guān)系基本上由被切削螺紋所需的節(jié)距決定。
As previously mentioned, the axial feed is automatically generated when cutting a thread by means of the lead screw, which drives the carriage.When the lead screw rotates a single revolution, the carriage travels a distance equal to the pitch of the lead screw.如前所述,當(dāng)依靠驅(qū)動(dòng)大拖板的絲桿切削螺紋時(shí)軸向進(jìn)給是自動(dòng)產(chǎn)生的。絲桿旋轉(zhuǎn)一圈,大拖板就行進(jìn)等于絲桿節(jié)距的一段距離。
Consequently, if the rotational speed of the lead screw is equal to that of the spindle(i.e., that of the workpiece), the pitch of the resulting cut thread is exactly equal to that of the lead screw.因此如果絲桿的旋轉(zhuǎn)速度等于心軸的轉(zhuǎn)速(即工件的轉(zhuǎn)速),生成切削螺紋的節(jié)距就正好等于絲桿的節(jié)距。
The pitch of the resulting thread being cut therefore always depends upon the ratio of the rotational speeds of the lead screw and the spindle: Pitch of the lead screw/ Desired pitch of workpiece=rpm of the workpiece/rpm of lead screw=spindle-to-carriage gearing ratio.所以被切削生成螺紋的節(jié)距總是取決于絲桿和心軸的轉(zhuǎn)速比:絲桿的節(jié)距/工件所需節(jié)距=工件轉(zhuǎn)速/絲桿轉(zhuǎn)速=心軸到大拖板的傳動(dòng)比。
This equation is useful in determining the kinematic linkage between the lathe spindle and the lead screw and enables proper selection of the gear train between them.這公式在決定車床心軸和絲桿之間的運(yùn)動(dòng)學(xué)關(guān)系時(shí)很有用,并且提供了正確挑選它們之間輪系的方法。
In thread cutting operations, the workpiece can either be held in the chuck or mounted between the two lathe centers for relatively long workpieces.The form of the tool used must exactly coincide with the profile of the thread to be cut, i.e., triangular tools must be used for triangular threads, and so on.在螺紋切削作業(yè)中,工件既能支撐于卡盤中,對(duì)相對(duì)較長的工件也能安裝在兩個(gè)車床頂尖之間。使用的刀具外形必須正好與要切削螺紋的輪廓一致,即三角形刀具必須用于三角形螺紋等等。
Knurling.Knurling is mainly a forming operation in which no chips are produced.It involves pressing two hardened rolls with rough filelike surfaces against the rotating workpiece to cause plastic deformation of the workpiece metal.滾花:滾花主要是一種不產(chǎn)生切屑的成型操作。它使用兩個(gè)帶有粗銼式表面的淬火滾輪壓在旋轉(zhuǎn)的工件上使工件金屬產(chǎn)生塑性變形。
Knurling is carried out to produce rough, cylindrical(or conical)surfaces, which are usually used as handles.Sometimes, surfaces are knurled just for the sake of decoration;there are different types of patterns of knurls from which to choose.滾花用于生成粗糙的圓柱(或圓錐)面,通常用來作手柄。有時(shí)表面滾花只為裝飾之故;有不同的滾花圖案類型可供選擇。Cutting Speeds and Feed切削速度和進(jìn)給
The cutting speed, which is usually given in surface feet per minute(SFM), is the number of feet traveled in the circumferential direction by a given point on the surface(being cut)of the workpiece in 1 minute.切削速度,通常用每分鐘表面英尺給出,就是一分鐘內(nèi)工件(被切削)表面給定點(diǎn)在圓周方向上行進(jìn)的英尺數(shù)。
The relationship between the surface speed and rpm can be given by the following equation:
SFM=πDN Where D=the diameter of the workpiece in feet N=the rpm 表面速度與轉(zhuǎn)速之間的關(guān)系可以用下式給出:
SFM=πDN 式中
D=用英尺表示的工件直徑 N=轉(zhuǎn)速
The surface cutting speed is dependant primarily upon the material being machined as well as the material of the cutting tool and can be obtained from handbooks, information provided by cutting tool manufacturers, and the like.表面切削速度主要由被切削材料和切削刀具材料決定,可以從手冊(cè)、切削刀具生產(chǎn)商提供的資料及類似的東西上查取。
Generally, the SFM is taken as 100 when machining cold-rolled or mild steel, as 50 when machining tougher metals, and as 200 when machining softer materials.For aluminum, the SFM is usually taken as 400 or above.There are also other variables that affect the optimal value of the surface cutting speed.一般而言,SFM當(dāng)機(jī)加工冷軋或低碳鋼時(shí)取100,機(jī)加工較堅(jiān)韌的金屬時(shí)取50,而機(jī)加工較軟材料時(shí)取200。對(duì)鋁而言,SFM通??扇?00以上。也還存在其它一些變量影響表面切削速度的最佳值。
These include the tool geometry, the type of lubricant or coolant, the feed, and the depth of cut.As soon as the cutting speed is decided upon, the rotational speed(rpm)of the spindle can be obtained as follows:
N=SFM/(πD)
其中包括刀具形狀、潤滑劑或冷卻液的類型、進(jìn)給和切削深度。切削速度一旦確定,心軸轉(zhuǎn)速(rpm)就能按下式得到:
N=SFM/(πD)
The selection of a suitable feed depends upon many factors, such as the required surface finish, the depth of cut, and the geometry of the tool used.Finer feeds produce better surface finish, whereas higher feeds reduce the machining time during which the tool is in direct contact with the workpiece.合適進(jìn)給的選擇取決于許多因素,例如所需表面光潔度、切削深度和所用刀具的幾何形狀。進(jìn)給越小生成的光潔度越好,而在刀具與工件直接接觸時(shí)進(jìn)給越大則可以減少機(jī)加工時(shí)間。
Therefore, it is generally recommended to use high feeds for roughing operations and finer feeds for finishing operations.Again, recommended values for feeds, which can be taken as guidelines, are found in handbooks and in information booklets provided by cutting tool manufacturers.所以對(duì)粗車一般推薦使用較大進(jìn)給,而精車則用較小進(jìn)給。再者,作為指導(dǎo)方針的進(jìn)給推薦值可以從手冊(cè)和切削刀具生產(chǎn)商提供的資料小冊(cè)子上找到。
第十二章 Drilling and Milling 鉆削
Drilling and Drills鉆削和鉆頭
Drilling involves producing through or blind holes in a workpiece by forcing a tool, which rotates around its axis, against the workpiece.鉆削就是通過迫使繞自身軸線旋轉(zhuǎn)的切削刀具進(jìn)入工件而在其上生成通孔或盲孔。Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole.In practice, two symmetrical cutting edges that rotate about the same axis are employed.因此,從旋轉(zhuǎn)軸線開始的切削范圍等于所需孔的半徑。實(shí)際上,使用的是兩條圍繞相同軸線旋轉(zhuǎn)的對(duì)稱切削刃。
Drilling operations can be carried out by using either hand drills or drilling machines.The latter differ in size and construction.Nevertheless, the tool always rotates around its axis while the workpiece is kept firmly fixed.This is contrary to drilling on a lathe.鉆削作業(yè)既能采用手鉆也能采用鉆床來實(shí)現(xiàn)。鉆床在尺寸和結(jié)構(gòu)上雖有差別,然而始終都是切削刀具圍繞自身軸線旋轉(zhuǎn)、工件穩(wěn)固定位的形式。這正好與在車床上鉆孔相反。Cutting Tool for Drilling Operation
In drilling operations, a cylindrical rotary-end cutting tool, called a drill, is employed.The drill can have either one or more cutting edges and corresponding flutes, which can be straight or helical.用于鉆削作業(yè)的切削刀具
在鉆削作業(yè)中,要用到被稱為鉆頭的圓柱形回轉(zhuǎn)端切削刀具。鉆頭可以有一條或多條直的或是螺旋狀的切削刃以及相應(yīng)的出屑槽。
The function of the flutes is to provide outlet passages for the chips generated during the drilling operation and also to allow lubricants and coolants to reach the cutting edges and the surface being machined.Following is a survey of the commonly used drills.出屑槽的功能是給鉆削作業(yè)中產(chǎn)生的切屑提供排出通道,并允許潤滑劑和冷卻液到達(dá)切削刃和正在被加工的表面。下面是常用鉆頭的概述。
Twist drill.The twist drill is the most common type of drill.It has two cutting edges and two helical flutes that continue over the length of the drill body, as shown in Fig.12.1.The drill also consists of a neck and a shank that can be either straight or tapered.麻花鉆:麻花鉆是最常用的鉆頭類型。它有兩條切削刃和兩條沿鉆頭體全長連續(xù)的螺旋狀出屑槽,如圖12.1所示。麻花鉆還包括鉆頸和鉆柄,鉆柄可以是直的也可以是錐形的。
In the latter case, the shank is fitted by the wedge action into the tapered socket of the spindle and has a tang, which goes into a slot in the spindle socket, thus acting as a solid means for transmitting rotation.錐形鉆柄通過楔入動(dòng)作安裝在主軸的錐形軸孔中,鉆柄上還有柄舌插入主軸軸孔中的插槽,從而作為傳遞轉(zhuǎn)動(dòng)的可靠方法。
On the other hand, straight-shank drills are held in a drill chuck that is, in turn, fitted into the spindle socket in the same way as tapered shank drills.另一方面,直柄鉆頭用鉆頭卡盤夾住,接下來鉆頭卡盤則象錐形鉆柄鉆頭一樣安裝在主軸軸孔內(nèi)。
As can be seen in Fig.12.1, the two cutting edges are referred to as the lips, and are connected together by a wedge, which is a chisel-like edge.The twist drill also has two margins, which enable proper guidance and locating of the drill while it is in operation.如圖12.1所示,兩條切削刃就是鉆唇,通過鑿子狀邊緣的楔形體連在一起。麻花鉆還有兩條導(dǎo)向邊,用于作業(yè)中鉆頭的正確導(dǎo)向和定位。
The tool point angle(TPA)is formed by the two lips and is chosen based on the properties of the material to be cut.The usual TPA for commercial drills is 118°, which is appropriate for drilling low-carbon steels and cast irons.兩條鉆唇形成鉆頂角,并根據(jù)被鉆削材料的性能來選取其大小。商品化鉆頭的鉆頂角一般為118°,這適用于鉆削低碳鋼和鑄鐵。
For harder and tougher metals, such as hardened steel, brass and bronze, larger TPAs(130°or 140°)give better performance.The helix angle of the flutes of the commonly used twist drills ranges between 24°and 30°.When drilling copper or soft plastics, higher values for the helix angle are recommended(between 35°and 45°).對(duì)于更硬更韌的金屬,諸如淬火鋼、黃銅和青銅,更大的鉆頂角(130°或140°)才能有更好的效果。麻花鉆常用的出屑槽螺旋角范圍為24°到 30°。鉆削紫銅或軟塑料時(shí),推薦采用更大的螺旋角(35°到45°)。
Twist drills are usually made of high-speed steel, although carbide-tipped drills are also available.The sizes of twist drills used in industrial practice range from 0.01 up to 3.25 in.(i.e., 0.25 up to 80 mm).雖然也有硬質(zhì)合金刀尖的鉆頭,麻花鉆一般用高速鋼制成。工業(yè)實(shí)際中使用的麻花鉆尺寸范圍為0.01到3.25英寸(即0.25到80毫米)。
Core drills.A core drill consists of the chamfer, body, neck, and shank, as shown in Fig.12.2.This type of drill may have either three or four flutes and equal number of margins, which ensure superior guidance, thus resulting in high machining accuracy.空心鉆:空心鉆包括斜面、鉆頭體、鉆頸和鉆柄,如圖12.2所示。這類鉆頭可以有三條或四條出屑槽及相同數(shù)量的保證良好導(dǎo)向的導(dǎo)向邊,這樣使得加工有高精度。
It can also be seen in Fig.12.2 that a core drill has flat end.The chamfer can have three or four cutting edges or lips, and the lip angle may vary between 90°and 120°.在圖12.2中同樣能看到,空心鉆具有平坦的端部。斜面可以有三或四條切削刃或鉆唇,并且鉆唇角可以在90°到120°之間變化。
Core drills are employed for enlarging previously made holes and not for originating holes.This type of drill is characterized by greater productivity, high machining accuracy, and superior quality of the drilled surfaces.空心鉆用于擴(kuò)大已有的孔而不是打孔。這類鉆頭具有較大生產(chǎn)率、高加工精度和優(yōu)良鉆削表面質(zhì)量的特性。
Gun drills.Gun drills are used for drilling deep holes.All gun drills are straight-fluted, and each has a single cutting edge.A hole in the body acts as a conduit to transmit coolant under considerable pressure to the tip of the drill.深孔鉆:深孔鉆用于鉆深孔。所有深孔鉆都是直出屑槽的,并且均為單切削刃。鉆頭體中有個(gè)孔作為導(dǎo)管在相當(dāng)大的壓力下將冷卻液傳送到鉆頭頂端。
There are two kinds of gun drills, namely, the center-cut gun drill used for drilling blind holes and the trepanning drill.The latter has a cylindrical groove at its center, thus generating a solid core, which guides the tool as it proceeds during the drilling operation.深孔鉆有兩種類型,即用于鉆盲孔的中心切削深孔鉆和套孔鉆。后者在其中心有一圓柱形溝槽,這樣能生成整體芯在鉆孔作業(yè)過程中引導(dǎo)鉆頭。
Spade drills.Spade drills are used for drilling large holes of 3.5 in.(90mm)or more.Their design results in a marked saving in cost of the tool as well as a tangible reduction in its weight, which facilitates its handling.Moreover, this type of drill is easy to grind.扁平鉆:扁平鉆用于鉆削3.5英寸(90毫米)或更大的大孔。其設(shè)計(jì)使得鉆頭成本明顯節(jié)省、重量切實(shí)減輕,重量輕又使操作更方便。此外這種鉆頭容易磨利。Milling and Milling Cutter銑削和銑刀
Milling is a machining process that is carried out by means of a multiedge rotating tool known as a milling cutter.銑削是采用被稱為銑刀的多刃旋轉(zhuǎn)刀具完成的機(jī)加工作業(yè)。
In this process, metal removal is achieved through combining the rotary motion of the milling cutter and linear motions of the workpiece simultaneously.Milling operations are employed in producing flat, contoured and helical surfaces as well as for thread-and gear-cutting operation.在此工藝中,金屬去除是通過銑刀的旋轉(zhuǎn)運(yùn)動(dòng)和工件的直線運(yùn)動(dòng)的組合實(shí)現(xiàn)的。銑削作業(yè)既可用于生成平面、輪廓面和螺旋面,也可用于切削螺紋和齒輪。
Each of the cutting edges of a milling cutter acts as an individual single-point cutter when it engages with the workpiece metal.Therefore, each of those cutting edges has appropriate rake and relief angles.在銑刀切削工件金屬時(shí),銑刀的每條切削刃都象一單獨(dú)的單刃刀具一樣作用。所以每條切削刃都適當(dāng)?shù)那昂蠼恰?/p>
Since only a few of the cutting edges are engaged with the workpiece at a time, heavy cuts can be taken without adversely affecting the tool life.In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling.由于同一時(shí)間只有部分切削刃切削工件,因此可以在對(duì)刀具壽命沒有不利影響的情況下承擔(dān)重型切削。事實(shí)上,銑削允許的切削速度和進(jìn)給比車削或鉆削高三到四倍。
Moreover, the quality of the surfaces machined by milling is generally superior to the quality of surfaces machined by turning, shaping, or drilling.此外,由銑削加工的表面質(zhì)量通常優(yōu)于車削、刨削或鉆削加工的表面質(zhì)量。
A wide variety of milling cutters is available in industry.This, together with the fact that a milling machine is a very versatile machine tool, makes the milling machine the backbone of a machining workshop.工業(yè)上可采用的銑刀類型眾多。連同銑床是極通用機(jī)床的事實(shí),使得銑床成為機(jī)加工車間的支柱。
As far as the direction of cutter rotation and workpiece feed are concerned, milling is performed by either of the following two methods.至于涉及到銑刀轉(zhuǎn)動(dòng)的方向和工件的進(jìn)給,銑削可以通過下列兩種方法之一進(jìn)行。
Up milling(conventional milling).In up milling the workpiece is fed against the direction of cutter rotation, as shown in Fig.12.3a.As we can see in that figure, the depth of cut(and consequently the load)gradually increases on the successively engaged cutting edges.逆銑(傳統(tǒng)銑削):在逆銑中,工件逆著銑刀轉(zhuǎn)動(dòng)的方向進(jìn)給,如圖12.3a所示。就像在此圖中能看到的那樣,切削深度(及作為結(jié)果的載荷)隨著切削刃持續(xù)進(jìn)入切削而逐漸增加。
Therefore, the machining process involves no impact loading, thus ensuring smoother operation of the machine tool and longer tool life.The quality of the machined surface obtained by up milling is not very high.Nevertheless, up milling is commonly used in industry, especially for rough cuts.所以,這種工藝沒有沖擊載荷,從而保證了機(jī)床的較平穩(wěn)運(yùn)行和較長壽命。通過逆銑所得機(jī)加工表面質(zhì)量不是很高。然而逆銑仍經(jīng)常被用在工業(yè)上,尤其是粗切削時(shí)。
Down milling(climb milling).As can be seen in Fig.12.3b, in down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the workpiece.It can also be seen that the maximum depth of cut is achieved directly as the cutter engages with the workpiece.順銑(同向銑削):如同在圖12.3b中看到的那樣,在順銑時(shí)刀具與工件之間接觸點(diǎn)上銑刀旋轉(zhuǎn)與進(jìn)給方向一致。還可以看到當(dāng)?shù)毒哌M(jìn)入工件切削時(shí)直接達(dá)到最大切削深度。This results in a kind of impact, or sudden loading.Therefore, this method cannot be used unless the milling machine is equipped with a backlash eliminator on the feed screw.The advantages of this method include higher quality of the machined surface and easier clamping of workpieces, since the cutting forces act downward.這會(huì)導(dǎo)致一種沖擊,或突然加載。因此,這種方法只有當(dāng)銑床在進(jìn)給螺栓上配備間隙消除器時(shí)才采用。這種方法的優(yōu)點(diǎn)包括機(jī)加工表面質(zhì)量較高和工件由于切削力向下作用而較容易夾緊。
Types of Milling Cutters
There is a wide variety of milling cutter shapes.Each of them is designed to perform effectively a specific milling operation.銑刀的類型
銑刀的形狀類型很多。其中每種都是為有效進(jìn)行特定的銑削作業(yè)而設(shè)計(jì)的。
Generally, a milling cutter can be described as a multiedge cutting tool having the shape of a solid of revolution, with the cutting teeth arranged either on the periphery or on an end face or on both.Following is a quick survey of the commonly used types of milling cutters.通常,銑刀可以被描述為具有旋轉(zhuǎn)實(shí)體形狀并將切削齒安裝在周邊或一到兩個(gè)端面上的多刃切削刀具。下面是常用銑刀類型的快速綜覽。
Plain milling cutter.A plain milling cutter is a disk-shaped cutting tool that may have either straight or helical teeth, as shown in Fig.12.4a.This type is always mounted on horizontal
milling machines and is used for machining flat surfaces.平面銑刀:平面銑刀是一種盤狀切削刀具,它可以具有直齒或螺旋齒,如圖12.4a所示。這類銑刀總是安裝在臥式銑床上,用于機(jī)加工平面。
Face milling cutter.A face milling cutter is also used for machining flat surfaces.It is bolted at the end of a short arbor, which is in turn mounted on a vertical milling machine.Fig.12.4b indicates a milling cutter of this type.端面銑刀:端面銑刀也可用于機(jī)加工平面。它用螺栓固定在短刀桿的端部,而短刀桿則依次安裝于立式銑床上。圖12.4b顯示了這類銑刀。
Plain metal slitting saw cutter.Fig.12.4c indicates a plain metal slitting saw cutter.we can see that it actually involves a very thin plain milling cutter.平面金屬開槽鋸刃銑刀:圖12.4c顯示了一種平面金屬開槽鋸刃銑刀。可以看到它其實(shí)是一種很薄的平面銑刀。
Side milling cutter.A side milling cutter is used for cutting slots, grooves, and splines.As shown in Fig.12.4d, it is quite similar to the plain milling cutter, the difference being that this type has teeth on the sides.As is the case with the plain cutter, the cutting teeth can be straight or helical.側(cè)銑刀:側(cè)銑刀用于切削狹槽、凹槽和花鍵槽。正如圖12.4d所示,它與平面銑刀十分相似,差別在于此類銑刀齒在側(cè)面。象平面銑刀的情況一樣,切削齒既可以是直的也可以是螺旋的。
Angle milling cutter.An angle milling cutter is employed in cutting dovetail grooves, ratchet wheels, and the like.Fig.12.4e indicates a milling cutter of this type.傾斜銑刀:傾斜銑刀用于切削燕尾槽、棘輪之類的。圖12.4e顯示了這類銑刀。
T-slot cutter.As shown in Fig.12.4f, a T-slot cutter involves a plain milling cutter with an integral shaft normal to it.As the name suggests, this type is used for milling T-slots.T型槽銑刀:如圖12.4f所示,T型槽銑刀包括了一個(gè)平面銑刀和一根垂直于它的整體軸。正像其名字所表明的,這類銑刀用于銑削T型槽。
End mill cutter.End mill cutters find common applications in cutting slots, grooves, flutes, splines, pocketing work, and the like.Fig.12.4g indicates an end mill cutter.The latter is always mounted on a vertical milling machine and can have two or four flutes, which may be either straight or helical.端面銑刀:端面銑刀在切削狹槽、凹槽、長凹槽、花鍵槽、凹狀工件之類時(shí)均能發(fā)現(xiàn)其普遍應(yīng)用。圖12.4g為端面銑刀。它總是安裝在立式銑床上,并具有兩到四條既可是直的也可是螺旋的長凹槽。
Form milling cutter.The teeth of a form milling cutter have a certain shape, which is identical to the section of the metal to be removed during the milling operation.Examples of this type include gear cutters, gear hobs, convex and concave cutters, and the like.From milling cutters are mounted on horizontal milling machines.成形銑刀:成形銑刀的齒具有特定的形狀,這個(gè)形狀與銑削時(shí)要切削的那部分金屬的形狀一致。這類銑刀的例子包括齒輪銑刀、齒輪滾刀、凸形和凹形銑刀等等。成形銑刀安裝在臥式銑床上。
Materials of Milling Cutters
The commonly used milling cutters are made of high-speed steel, which is generally adequate for most jobs.銑刀的材料
普通使用的銑刀用高速鋼制造,這對(duì)一般大多數(shù)工作已足夠。
Milling cutters tipped with sintered carbides or cast nonferrous alloys as cutting teeth are usually employed for mass production, where heavier cuts and/or high cutting speeds are required.對(duì)大規(guī)模生產(chǎn)而言,因?yàn)槠湫枰匦颓邢骱?或高切削速度,銑刀頂端常裝有燒結(jié)碳化物或有色金屬碳合金作為切削齒。
第十三章 Jigs and Fixtures
Introduction
導(dǎo)言
It has already been stated that the workpiece must be located relative to the cutting tool, and be secured in that position.After the workpiece has been marked out, it is still necessary to position it with respect to the machine movements, and to clamp it in that position before machining is started.已經(jīng)說明了工件必須相對(duì)于切削刀具定位并確保到位。工件劃線后,仍有必要將其相對(duì)于切削運(yùn)動(dòng)定位,并在機(jī)加工開始前把它裝夾到位。
When several identical workpieces are to be produced the need to mark out each part is eliminated by the use of jigs and fixtures, but if a casting or forging is involved, a trial workpiece is marked out, to ensure that the workpiece can be produced from it, and to ensure that ribs, cores, etc.have not become misplaced.當(dāng)要加工若干同樣的工件時(shí),使用鉆模和夾具可以不必在每個(gè)工件上劃線;但對(duì)鑄件或鍛件而言,還需取一試驗(yàn)工件劃線以保證照此加工不會(huì)將加強(qiáng)肋、型芯等放錯(cuò)位置。
Jigs and fixtures are alike in that they both incorporate devices to ensure that the workpiece is correctly located and clamped, but they differ in that jigs incorporate means of tool guiding during the actual cutting operation, and fixtures do not.鉆模和夾具的相似點(diǎn)是它們都把保證工件正確定位和夾緊的裝置相結(jié)合,它們的不同在于鉆模在實(shí)際切削作業(yè)中還能與刀具導(dǎo)向方法相結(jié)合,而夾具則不能。
In practice, the only cutting tools that can be guided while actually cutting are drills, reamers, and similar cutters;and so jigs are associated with drilling operations, and fixtures with all other operations.Fixtures may incorporate means of setting the cutting tools relative to the location system.實(shí)際上,在真實(shí)切削中能被導(dǎo)向的切削刀具只有鉆頭、鉸刀和類似的刀具;因此鉆模用于鉆削作業(yè),而夾具用于其余作業(yè)。夾具可以與切削刀具相對(duì)定位系統(tǒng)裝夾的方法結(jié)合在一起。
The advantages of jigs and fixtures can be summarised as follows:
1)Marking out and other measuring and setting out methods are eliminated;
2)Unskilled workers may proceed confidently and quickly in knowledge that the workpiece can be positioned correctly, and the tools guided or set;
鉆模和夾具的優(yōu)點(diǎn)可歸納如下:
1)可以省去劃線和其它測(cè)量及放樣程序;
2)在知道工件能正確定位、刀具能恰當(dāng)導(dǎo)向或裝夾的情況下,不熟練的工人也能自信而快速地操作;
3)the assembly of parts is facilitated, since all components will be identical within small limits, and “trying” and filing of work is eliminated;
4)The parts will be interchangeable, and if the product sold over a wide area, the problem of spare parts will be simplified.3)由于所有零件在較小極限范圍內(nèi)是相同的,可以省掉工件的‘試裝’和銼削,所以零件裝配很方便;
4)零件具有互換性,這樣如果產(chǎn)品在較大范圍內(nèi)銷售的話,備件問題將簡(jiǎn)單化。
Bolt holes often have 1.5mm or even 3.0mm clearance for the bolt, and the reader may doubt the necessity of making precision jigs for such work.It must be remembered that the jigs, once made, will be used on many components, and the extra cost of an accurately made jig is spread over a large output.螺栓孔常給螺栓留出1.5毫米或甚至3.0毫米的間隙,讀者可能會(huì)懷疑為這樣的工作制造精密鉆模的必要性。但要記住,這種鉆模一旦造好,可用于許多零部件,精確制造鉆模的額外成本可分?jǐn)傇诖罅慨a(chǎn)品上。
Furthermore, it is surprising how small errors accumulate in a mechanism during its assembly.When a clearance is specified, it is better to ensure its observance, rather than to allow careless marking out and machining to encroach upon it.
此外,這樣做在裝配機(jī)械裝置時(shí)其累積誤差之小也是令人驚訝的。在確定一個(gè)間隙時(shí),最好能保證它的習(xí)慣要求,而不是隨便劃線和機(jī)加工使其超出正常的界限。
1)The location of workpiece.Fig.13.1 represents a body that is completely free in space.In this condition it has six degrees of freedom.Consider these freedoms with respect to the three mutually perpendicular axes XX, YY, and ZZ.1)工件的定位:圖13.1表示一個(gè)在空間完全自由的物體,在這種情況下它具有六個(gè)自由度。相對(duì)于三根互相垂直的坐標(biāo)軸XX、YY和ZZ來考慮這些自由度。
The body can move along any of these axes;it therefore has three freedoms of translation.It can also rotate about any of the three axes;it therefore has three freedoms of rotation.The total number of freedoms is six.When work is located, as many of these freedoms as possible must be eliminated, to ensure that the operation is performed with the required accuracy.此物體能沿三根坐標(biāo)軸的任意一根移動(dòng);這樣就具有三個(gè)平移自由度。它也能圍繞三根坐標(biāo)軸的任意一根回轉(zhuǎn);這樣它又具有三個(gè)旋轉(zhuǎn)自由度。總的自由度數(shù)目是六個(gè)。當(dāng)工件被定位時(shí),必須盡可能多地消除這些自由度,以保證作業(yè)按要求精度進(jìn)行。
Accuracy is ensured by machining suitable location features as early as possible, and using them for all location, unless other considerations mean that other location features must be used.If it is necessary, the new location features must be machined as a result of location from the former location features.除非有必要采用另外定位要素的其它考慮,精度可通過盡可能早地加工合適的定位要素并采用它們進(jìn)行所有定位來保證。如果必要的話,新的定位要素必須作為先前的定位要素的定位結(jié)果來加工。
2)The clamping of the workpiece.The clamping system must be such that the workpiece is held against the cutting forces, and the clamping forces must not be so great as to cause the workpiece to become distorted or damaged.2)工件的裝夾:裝夾系統(tǒng)必須使工件對(duì)著切削力夾持,而且裝夾力又不能大得引起
工件變形或損壞。
The workpiece must be supported beneath the point of clamping, to ensure that the forces are taken by the main frame of the jig or fixture, and on to the machine table and bed.When jigs and fixtures are designed, the clamping system is designed to ensure that the correct clamping force is applied, and that the clamps can be operated quickly but with safety.工件必須在裝夾點(diǎn)下被支撐,以保證這些力由鉆模或夾具的主框架來承受并傳遞給機(jī)器臺(tái)和床身。在設(shè)計(jì)鉆模和夾具時(shí),要同時(shí)設(shè)計(jì)裝夾系統(tǒng)來保證提供恰當(dāng)?shù)难b夾力,并使裝夾操作快速而安全。
Definition of a Drill Jig鉆模的定義
A drill jig is a device for ensuring that a hole to be drilled, tapped, or reamed in a workpiece will be machined in the proper place.鉆模是一種確保在工件正確位置進(jìn)行鉆孔、攻絲或鉸孔加工的裝置。
Basically it consists of a clamping device to hold the part in position under hardened-steel bushings through which the drill passes during the drilling operation.The drill is guided by the bushings.它基本上由在淬硬鋼襯套下將零件夾持到位的夾持裝置組成,鉆孔作業(yè)中鉆頭穿過這些襯套,通過它們來導(dǎo)向。
If the workpiece is of simple construction, the jig may be clamped on the workpiece.In most cases, however, the workpiece is held by the jig, and the jig is arranged so that the workpiece can be quickly inserted and as quickly removed after the machining operation is performed.如果工件結(jié)構(gòu)比較簡(jiǎn)單,鉆??蓨A持在工件上。然而大多數(shù)情況下,工件由鉆模來夾持,并且把鉆模設(shè)計(jì)成能將工件迅速裝入而在加工后同樣能很快取出。
Jigs make it possible to drill, ream, and tap holes at much greater speeds and with greater accuracy than when the holes are produced by conventional hand methods.Another advantage is that skilled workers are not required when jigs are used.Responsibility for the accuracy of hole location is taken from the operator and given to the jig.相對(duì)于用常規(guī)的手工方法加工孔,鉆模使得鉆孔、鉸孔和攻絲速度快很多而且精度更高成為可能。另一個(gè)優(yōu)點(diǎn)是采用鉆模時(shí)不需要熟練工人。保證孔定位精度的責(zé)任從操作者身上轉(zhuǎn)移到了鉆模上。
The term jig should be used only for devices employed while drilling, reaming, or tapping holes.It is not fastened to the machine on which it is used and may be moved around on the table of the drilling machine to bring each bushing directly under the drill.Jigs physically limit and control the path of the cutting tool.鉆模這個(gè)術(shù)語只用在服務(wù)于鉆孔、鉸孔或攻絲的裝置上。它不固定在使用它的鉆床上,它能在鉆床工作臺(tái)上到處移動(dòng)以使每個(gè)襯套都直接位于鉆頭下。鉆模有形地限制和控制鉆削刀具的路徑。
If the operation includes machining operations like milling, planing, shaping, turning, etc., the term fixture should be used.A fixture holds the work during machining operations but does not contain special arrangements for guiding the cutting tool ,as drill jigs do.如果作業(yè)還包括其它象銑削、刨削、成型、車削等機(jī)加工,則應(yīng)采用夾具這一術(shù)語。夾具在機(jī)加工作業(yè)時(shí)夾持工件,但它不象鉆模那樣包含引導(dǎo)切削刀具的特殊布置。Typical Jigs and Fixtures典型的鉆模和夾具
Typical drill jig.Figure 13.2 illustrates a drilling jig for drilling four holes in the flange of a workpiece that has been completed except for the four holes.典型的鉆模:圖13.2所示為一個(gè)能在某工件的法蘭上鉆四個(gè)孔的鉆模,該工件除了這四個(gè)孔外已全部完成。
The workpiece has an accurately machined bore, and is located from the bore and the end face, from a cylindrical post.There is no need to control the rotational position about the axis of the bore, because up to the time when the holes are drilled, it is symmetrical about that axis.此工件有一精確機(jī)加工的大孔,因此通過一圓柱體采用該孔和工件端面定位。由于直至鉆這些小孔時(shí),工件都對(duì)稱于大孔軸線,所以沒必要控制圍繞大孔軸線回轉(zhuǎn)的位置。
The four bushes used to control the drill are held in the drill plate, which, with the hand nut, is used to clamp the workpiece against the base of the fixture.四個(gè)控制鉆頭的襯套裝在鉆板里,連同手?jǐn)Q螺母一起用于靠著夾具基座夾持工件。
Typical milling fixture.Figure 13.3 illustrates a simple milling fixture for milling the slot in the otherwise completed workpiece shown.The workpiece is located from two of the four holes in its base, and from the underside of the base.典型的銑削夾具:圖13.3所示為一用于在圖示其它工序都完成的工件上銑槽的簡(jiǎn)單銑削夾具。此工件采用其基座上四孔中的兩孔和基座的底面定位。
The workpiece is clamped in position, and cutter is located against the setting block, which provides setting or cutter position and depth of cut.工件被夾持到位,銑刀靠著提供安裝或銑刀位置及切削深度的安裝臺(tái)定位。
The fixture must be positioned relative to the machine table, this is done by engaging the two tenons at the bottom of the fixture in the slot in the machine table.The fixture is secured to the machine table with T-bolts, also engaging in the slots in the table(Fig.13.3).夾具必須相對(duì)于銑床工作臺(tái)定位,這可通過把夾具底部的兩個(gè)凸榫插入工作臺(tái)上的槽中來實(shí)現(xiàn)。夾具用T型螺栓固定于銑床工作臺(tái),同時(shí)與工作臺(tái)上的槽接合(圖13.3)。
Dimensioning 標(biāo)注尺寸
The design of a machine includes many factors other than those of determining the loads and stresses and selecting the proper materials.機(jī)械設(shè)計(jì)除了計(jì)算載荷和應(yīng)力、選擇合適的材料外,還包括許多其它因素。
Before construction or manufacture can begin, it is necessary to have complete assembly and detail drawings to convey all necessary information to the shop men.The designer frequently is called upon to check the drawings before they are sent to the shop.Much experience and familiarity with manufacturing processes are needed before one can become conversant with all phases of production drawings.在建造或制造開始前,完成裝配圖和零件圖以把必要信息傳達(dá)給車間工人是必須的。在送往車間前設(shè)計(jì)者常常被召集來檢查圖紙。而在精通生產(chǎn)圖紙的所有情況之前,需要有許多經(jīng)驗(yàn)
并熟悉制造工藝。
Drawings should be carefully checked to see that the dimensioning is done in a manner that will be most convenient and understandable to the production departments.It is obvious that a drawing should be made in such a way that it has one and only one interpretation.圖紙必須仔細(xì)檢查其尺寸是否按生產(chǎn)部門最方便易懂的方式標(biāo)注。很明顯圖紙應(yīng)該只有唯一的解釋。
In particular, shop personnel should not be required to make trigonometric or other involved calculations before the production machines can be set up.Dimensioning is an involved subject and long experience is required for its mastery.尤其是不能要求車間工人在生產(chǎn)機(jī)械安排前進(jìn)行三角或其它復(fù)雜的計(jì)算。
尺寸標(biāo)注是一項(xiàng)復(fù)雜的工作,要掌握它需要有豐富的經(jīng)驗(yàn)。
Tolerances must be placed on the dimensions of a drawing to limit the permissible variations in size because it is impossible to manufacture a part exactly to a given dimension.由于要把零件加工到正好為給定尺寸是不可能的,因此圖紙的尺寸必須加上公差以限制其可允許的變化。
Although small tolerances give higher quality work and a better operating mechanism, the cost of manufacture increases rapidly as the tolerances are reduced, as indicated by the typical curve of Fig14.1.It is therefore important that the tolerances be specified at the largest values that the operating or functional considerations permit.雖然較小公差能得到較高加工質(zhì)量和較好操作機(jī)構(gòu),但隨著公差的減小制造成本會(huì)迅速增加,如圖14.1的典型曲線所示。因此公差被定為從操作或功能考慮允許的最大值是重要的。
Tolerances may be either unilateral or bilateral.In unilateral dimensioning, one tolerance is zero, and all the variations are given by the other tolerance.In bilateral dimensioning, a mean dimension is used which extends to the midpoint of the tolerance zone with equal plus and minus variations extending each way from this dimension.公差既可以是單向的也可以是雙向的。單向標(biāo)注有一公差為零,所有變化都由另一公差給定。而雙向標(biāo)注則采用一平均尺寸,它將公差帶中點(diǎn)從該尺寸雙向擴(kuò)展為相等的正負(fù)變化范圍。
The development of production processes for large-volume manufacture at low cost has been largely dependent upon interchangeability of component parts.Thus the designer must determine both the proper tolerances for the individual parts, and the correct amount of clearance or interference to permit assembly with the mating parts.大規(guī)模低成本制造生產(chǎn)工藝的發(fā)展很大程度取決于組成零件的互換性。因此設(shè)計(jì)者必須確定單個(gè)零件的合適公差以及配合零件裝配允許的正確間隙或過盈量。
The manner of placing tolerances on drawings depends somewhat on the kind of product or type of manufacturing process.If the tolerance on a dimension is not specifically stated, the drawing should contain a blanket note which gives the value of the tolerance for such dimensions.在圖紙上標(biāo)注公差的方法相當(dāng)程度上依賴于產(chǎn)品的性質(zhì)或制造工藝的類型。如果尺寸公差沒有特別注明,圖紙應(yīng)該包含一個(gè)給出這些尺寸公差值的普遍適用注釋。
However, some companies do not use blanket notes on the supposition that if each dimension is considered individually, wider tolerances than those called for in the note could probably be specified.In any event it is very important that a drawing be free from ambiguities and be subject only to a single interpretation.然而有些公司不采用普遍適用注釋,假定每個(gè)尺寸是單獨(dú)被考慮的,可能會(huì)規(guī)定出比注釋中
要求的更寬的公差。在任何情況下圖紙不模棱兩可并只服從于單一的解釋是十分重要的。Dimension and Tolerance尺寸和公差
In dimensioning a drawing, the numbers placed in the dimension lines represent dimension that are only approximate and do not represent any degree of accuracy unless so stated by the designer.在圖紙標(biāo)注尺寸時(shí),除非設(shè)計(jì)者有意標(biāo)明,注在尺寸線上的數(shù)字代表的尺寸僅僅是近似的,并不代表任何精度等級(jí)。
To specify a degree of accuracy, it is necessary to add tolerance figures to the dimension.Tolerance is the amount of variation permitted in the part or the total variation allowed in a given dimension.為了詳細(xì)標(biāo)明精度等級(jí),有必要在尺寸上增加公差數(shù)字。公差是零件允許的變動(dòng)量或給定尺寸允許的總變動(dòng)。
A shaft might have a nominal size of 2.5in.(63.5mm), but for practical reasons this figure could not be maintained in manufacturing without great cost.Hence, a certain tolerance would be added and, if a variation of±0.003in.(±0.08mm)could be permitted, the dimension would be stated 2.500±0.003(63.5±0.08mm).一根軸可能的名義尺寸為2.5in.(63.5mm),但由于實(shí)際原因不用大成本是不能在制造中保持這個(gè)數(shù)字的,因此要增加確定的公差。如果允許有±0.003in.(±0.08mm)的變化,則此尺寸可表達(dá)為2.500±0.003(63.5±0.08mm)。
Dimensions given close tolerances mean that the part must fit properly with some other part.Both must be given tolerances in keeping with the allowance desired, the manufacturing processes available, and the minimum cost of production and assembly that will maximize profit.具有緊密公差的尺寸表示該零件必須恰當(dāng)?shù)嘏c某些其它零件配合。所采用的制造工藝和使利潤最大化的最小生產(chǎn)及裝配成本都要求給定公差以保持所需允差。
Generally speaking, the cost of a part goes up as the tolerance is decreased.If a part has several or more surfaces to be machined, the cost can be excessive when little deviation is allowed from the nominal size.一般而言,零件的成本隨著公差的減小而上升。如果一個(gè)零件有若干或較多表面要機(jī)加工,且?guī)缀醪辉试S偏離名義尺寸,則成本會(huì)超過正常合理的界限。
Allowance, which is sometimes confused with tolerance, has an altogether different meaning.It is the minimum clearance space intended between mating parts and represents the condition of tightest permissible fit.允差,有時(shí)會(huì)跟公差混淆,但其具有完全不同的含義。它是配合零件之間最小的預(yù)期間隙空間,代表著允許的最緊配合條件。
If a shaft, size 1.498-0.003, is to fit a hole of size 1.500+0.003, the minimum size hole is 1.500 and the maximum size shaft is 1.498.Thus the allowance is 0.002 and the maximum clearance is 0.008 as based on the minimum shaft size and maximum hole dimension.如果一根尺寸為1.498-0.003的軸與尺寸為1.500+0.003的孔配合,孔的最小尺寸為1.500而軸的最大尺寸為1.498。這樣允差就是0.002,而由最小軸尺寸和最大孔尺寸形成的最大間隙為0.008。
Tolerances may be either unilateral or bilateral.Unilateral tolerance means that any variation is made in only one direction from the nominal or basic dimension.Referring to the previous example, the hole is dimensioned 1.500+0.003, which represents a unilateral tolerance.公差可以是單向的也可以是雙向的。單向公差意味著任何變動(dòng)都是只從名義或基本
尺寸出發(fā)向一個(gè)方向變動(dòng)的。引用前例,孔的尺寸標(biāo)注為1.500+0.003,它表示了一個(gè)單向公差。
If the dimensions were given as 1.500±0.003, the tolerance would be bilateral;that is, it would vary both over and under the nominal dimension.The unilateral system permits changing the tolerance while still retaining the same allowance or type of fit.如果尺寸標(biāo)為1.500±0.003,就是雙向公差;即它可以在名義尺寸之上或之下變化。單向體系允許在依然保留相同允差或配合類型的情況下改變公差。
With the bilateral system, this is not possible without also changing the nominal size dimension of one or both of the two mating parts.In mass production, where mating parts must be interchangeable, unilateral tolerances are customary.To have an interference or force fit between mating parts, the tolerances must be such as to create a zero or negative allowance.而雙向體系在不同時(shí)改變一個(gè)或兩個(gè)配合零件名義尺寸的情況下,這是不可能做到的。大規(guī)模生產(chǎn)中配合零件必須能互換,單向公差是經(jīng)常遇到的。為了使配合零件之間具有過盈或強(qiáng)制配合,公差必須產(chǎn)生零或負(fù)允差。
Tolerances, Limits and Fits公差、極限和配合
The drawing must be a true and complete statement of the designer’s requirements expressed in such a way that the part is convenient to manufacture.圖紙必須按方便制造零件的方式將設(shè)計(jì)者的要求真實(shí)和完整地表達(dá)出來。
Every dimension necessary to define the product must be stated once only and not repeated in different views.Dimensions relating to one particular feature, such as the position and size of a hole, should, where possible, appear on the same view.對(duì)每一描述產(chǎn)品所需的尺寸都只須標(biāo)注一次而不必在不同的視圖中重復(fù)。有關(guān)同一特性的尺寸,諸如孔的位置和大小,如果可能應(yīng)出現(xiàn)在同一視圖上
There should be no more dimensions than are absolutely necessary, and no feature should be located by more than one dimension in any direction.除絕對(duì)需要的尺寸外,不應(yīng)該有更多的尺寸;而在任意方向上,只能在一個(gè)尺寸上標(biāo)注特性要求。
It may be necessary occasionally to give an auxiliary dimension for reference, possibly for inspection.When this is so, the dimension should be enclosed in a bracket and marked for reference.Such dimensions are not governed by general tolerances.偶爾也可能為了檢查而必須給出供參考的輔助尺寸。在這種情況下,尺寸應(yīng)該用括號(hào)括起來,以便參考。這樣的尺寸不受通用公差控制。
Dimensions that affect the function of the part should always be specified and not left as the sum or difference of other dimensions.影響零件功能的尺寸總是應(yīng)該標(biāo)注的而不要留作其它尺寸的和或差。
If this is not done, the total permissible variation on that dimension will form the sum or difference of the other dimensions and their tolerances, and this will result in these tolerances having to be made unnecessarily tight.The overall dimension should always appear.如果不是這樣,那尺寸允許的總的變化將形成其它尺寸及它們的公差的和或差,這會(huì)導(dǎo)致這些公差不得不定得過緊。總尺寸一般應(yīng)該標(biāo)注。
All dimensions must be governed by the general tolerance on the drawing unless otherwise stated.Usually, such a tolerance will be governed by the magnitude of the dimension.Specific tolerances must always be stated on dimensions affecting function or interchangeability.除非另行說明,所有尺寸都必須受圖上的通用公差控制。一般這樣的公差受到尺寸量值的控制。在影響功能或互換性的尺寸上必須標(biāo)注專門的公差。
A system of tolerances is necessary to allow for the variations in accuracy that are bound to occur during manufacture, and still provide for interchangeability and correct function of the part.為了允許在制造過程中必然會(huì)發(fā)生的精度變化,并提供零件的互換性和正確功能,一個(gè)公差系統(tǒng)是必需的。
A tolerance is the difference in a dimension in order to allow for unavoidable imperfections in workmanship.The tolerance range will depend on the accuracy of the manufacturing organisation, the machining process and the magnitude of the dimension.公差是為了允許工藝上不可避免缺陷而存在的尺寸上的不同。公差范圍取決于制造機(jī)構(gòu)的精度、機(jī)加工過程和尺寸的量值。
The greater the tolerance range, the cheaper the manufacturing process.A bilateral tolerance is one where the tolerance range is disposed on both sides of the nominal dimension.A unilateral tolerance is one where the tolerance zone is on one side only of the nominal dimension, in which case the nominal dimension may form one of the limits.公差范圍越大,則制造過程的成本就越低。雙向公差是在公稱尺寸兩側(cè)都有公差帶的公差。單向公差是僅在公稱尺寸一側(cè)有公差帶的公差,在這種情況下公稱尺寸成了兩個(gè)極限中的一個(gè)。
Limits are the extreme dimensions of the tolerance zone.For example, nominal dimension
30mm tolerance
limits
極限是公差帶的極限尺寸。例如公稱尺寸30毫米 公差
極限
Fits depend on the relationship between the tolerance zones of two mating parts, and may be broadly classified into a clearance fit with positive allowance, a transition fit where the allowance may be either positive or negative(clearance or interference), an interference fit where the allowance is always negative.配合取決于兩配合零件公差帶之間的關(guān)系,并且可以概括地分為具有正允差的間隙配合,允差可以是正或負(fù)的過渡配合和總是負(fù)允差的過盈配合。Type of Limits and Fits極限和配合的類型
The ISO System of Limits and Fits, widely used in a number of leading metric countries, is considerably more complex than the ANSI system.在一些最主要采用公制的國家中廣泛使用的ISO的極限和配合系統(tǒng),比ANSI的極限和配合系統(tǒng)要復(fù)雜得多。
In this system, each part has a basic size.Each limit of size of a part, high and low, is defined by its deviation from the basic size, the magnitude and sign being obtained by subtracting the basic size from the limit in question.The difference between the two limits of size of a part is called the tolerance, an absolute amount without sign.在這個(gè)系統(tǒng)中,每個(gè)零件都有基本尺寸。零件尺寸的每一極限,不管大小,都通過對(duì)基本尺寸的偏差來定義;其量值和符號(hào)由正被討論的極限減去基本尺寸得到。零件尺寸的兩個(gè)極限之差稱為公差,這是一個(gè)沒有符號(hào)的絕對(duì)量值。
There are three classes of fits: 1)clearance fits, 2)transition fits(the assembly may have either clearance or interference), and 3)interference fits.存在三種配合:1)間隙配合,2)過渡配合(裝配后可以有間隙或過盈),和3)過盈配合。
Either a shaft-basis system or a hole-basis system may be used.For any given basic size, a range of tolerances and deviations may be specified with respect to the line of zero deviation,called the zero line.基軸制或基孔制均可采用。對(duì)任何給定的基本尺寸,公差范圍和偏差可以相對(duì)于被稱為零線的零偏差線來確定。
The tolerance is a function of the basic size and is designated by a number symbol, called the grade—thus the tolerance grade.公差是基本尺寸的函數(shù) 并通過一個(gè)被稱為等級(jí)的數(shù)字符號(hào)標(biāo)明—即公差等級(jí)。
The position of the tolerance with respect to the zero line also a function of the basic size—is indicated by a letter symbol(or two letters), a capital letter for holes and a lowercase letter for shafts.Thus the specification for a hole and shaft having a basic size of 45 mm might be 45H8/g7.公差相對(duì)于零線的位置同樣為基本尺寸的函數(shù)通過一個(gè)或兩個(gè)字母符號(hào)表達(dá),大寫字母表示孔而小寫字母表示軸。這樣基本尺寸為45毫米的一個(gè)孔和軸配合規(guī)格可能是45H8/g7。
Twenty standard grades of tolerances are provided, called IT01, IT0, IT1~18, providing numerical values for each nominal diameter, in arbitrary steps up to 500mm(for example 0~3, 3~6,6~10,......, 400~500 mm).ISO規(guī)定了二十種標(biāo)準(zhǔn)的公差等級(jí),稱之為IT01,IT0,IT1~18,給在直至500毫米強(qiáng)行分段(例如0~3,3~6,6~10,......, 400~500毫米)中的公稱直徑提供具體數(shù)值。
The value of the tolerance unit, i, for grades 5~16 isWhere i is in microns and D in millimeters.對(duì)5~16級(jí)而言,公差單位i的值可用下式計(jì)算這里i的單位是微米,而D的單位是毫米。
Standard shaft and hole deviations similarly are provided by sets of formulas, however, for practical application, both tolerances and deviations are provided in three sets of rather complex tables.標(biāo)準(zhǔn)的軸和孔偏差同樣都由若干公式提供;然而對(duì)實(shí)際應(yīng)用,公差和偏差都在三張相當(dāng)復(fù)雜的表格中規(guī)定了。
Additional tables give the values for basic sizes above 500 mm and for “Commonly Used Shafts and Holes” in two categories—“General Purpose” and “Fine Mechanisms and Horology”.對(duì)基本尺寸大于500毫米和在“一般用途”和“精密機(jī)械和鐘表”兩個(gè)類別中的“常用的軸和孔”而言,由附加的表格給出數(shù)值
第二篇:英語課文翻譯
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? 參考譯文
第一單元
與自然力量抗?fàn)?課文A 就拿拿破侖和希特勒兩人來說吧,他們所向披靡,便以為自己戰(zhàn)
冰雪衛(wèi)士
奈拉·B·史密斯
1812年,法國皇帝拿破侖·波拿巴率大軍入侵俄羅斯。他準(zhǔn)備好俄羅斯人民會(huì)為保衛(wèi)祖國而奮勇抵抗。
他準(zhǔn)備好在俄羅斯廣袤的國土上要經(jīng)過長途跋涉才能進(jìn)軍首都莫斯科。但他沒有料到在莫斯科他會(huì)遭遇勁敵——俄羅斯陰冷凄苦的寒冬。
1941年,納粹德國元首阿道夫·希特勒進(jìn)攻當(dāng)時(shí)被稱作蘇聯(lián)的俄羅斯。希特勒的軍事實(shí)力堪稱無敵。
他的戰(zhàn)爭(zhēng)機(jī)器掃除了歐洲絕大部分地區(qū)的抵抗。希特勒希望速戰(zhàn)速?zèng)Q,但是,就像在他之前的拿破侖一樣,他得到的是痛苦的教訓(xùn)。仍是俄羅斯的冬天助了蘇維埃士兵一臂之力。拿破侖發(fā)起的戰(zhàn)役
1812年春,拿破侖在俄國邊境屯兵60萬。這些士兵受過良好訓(xùn)練,作戰(zhàn)力強(qiáng),裝備精良。這支軍隊(duì)被稱為大軍。拿破侖對(duì)馬到成功充滿自信,預(yù)言要在5個(gè)星期內(nèi)攻下俄國。
不久,拿破倉的大軍渡過涅曼河進(jìn)入俄國。拿破侖期盼著的速?zèng)Q速勝遲遲沒有發(fā)生。令他吃驚的是,俄國人并不奮起抵抗。相反.他們一路東撒,沿途焚毀莊稼和民居。大軍緊追不舍,但它的長驅(qū)直入很快由于糧草運(yùn)輸緩慢而停頓下來。
到了8月,法俄兩軍在斯摩棱斯克交戰(zhàn),這一戰(zhàn)役中,雙方各有上萬人陣亡??墒嵌韲巳阅茉谧约旱膰辽侠^續(xù)后撤。拿破侖未能取得決定性的勝利。此刻他面臨著一個(gè)重要抉擇。是繼續(xù)追擊俄國軍隊(duì),還足把軍隊(duì)駐扎在斯摩棱斯克,在那兒度過將到的冬天?
拿破侖孤注一擲,決定向遠(yuǎn)在448公里之外的莫斯科進(jìn)發(fā)。1 812年9月7日,法俄兩軍在莫斯科以西112公里外的鮑羅季諾激戰(zhàn),夜幕降臨時(shí),3萬名法國士兵以及4萬4千名俄國士兵或傷或亡,倒在了戰(zhàn)場(chǎng)上。
俄國軍隊(duì)再次撤往安全之處。拿破侖順利進(jìn)入莫斯科,然而,對(duì)該市的占領(lǐng)成為毫無意義的勝利。俄國人棄城而走。法國人進(jìn)城不久,一場(chǎng)熊熊大火燒毀丁整個(gè)城市的三分之二。拿破侖向亞歷山大一世提出停戰(zhàn),但沙皇深知他可以等待時(shí)機(jī):“且讓俄羅斯的嚴(yán)冬為我們戰(zhàn)斗吧?!?/p>
拿破侖很快意識(shí)到,他無法在冬天向遠(yuǎn)在莫斯科的軍隊(duì)供應(yīng)糧草、提供御寒衣物和宿營之地。1812年10月,他命令大軍撤出莫斯科。
法軍的撤離成為一場(chǎng)噩夢(mèng)。俄國人出沒于田野與森林,采用打了就跑的戰(zhàn)術(shù),向法國人發(fā)起攻擊。剛出莫斯科城,氣溫就降到攝氏零下4度。11月3目降了初雪。困乏的馬匹倒地而死。大炮陷入雪中。裝備只得被用作燃料焚燒。士兵們?nèi)静鏊?。法國士兵拖著腳步行進(jìn),一路上留下無數(shù)死尸。
正當(dāng)俄羅斯軍隊(duì)集聚兵力之時(shí),法國人卻不得不逃離俄國,以避免注定的失敗。在別列茲那河,俄國人焚燒了漲水的河道上的橋粱,差點(diǎn)將后撤的法軍團(tuán)于河邊。僥幸的是,拿破侖居然突擊造起兩座橋。成千上萬法國士兵得以逃脫,但卻損失了5萬人。渡過別列茲拿河,潰不成軍的幸存者一瘸一拐地向維爾紐行進(jìn)。
拿破侖發(fā)兵60萬進(jìn)入俄國,只有不到10萬士兵返回。元?dú)獯髠姆▏婈?duì)在歐洲繼續(xù)西撤。不久,英國、奧地利、俄國以及普魯士組成強(qiáng)大的聯(lián)盟,攻擊這些 1 ? ?
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散兵游勇。1814年3月,巴黎被攻占。拿破侖退位去過流放生活,他締造的帝國隨之滅亡。希特勒的入侵
到1941年初,納粹德國元首阿道夫·希特勒已經(jīng)控制了歐洲大部分地區(qū)。希特勒的德意志帝國的東部與蘇聯(lián)毗鄰。1941年6月22曰,希特勒不宣而戰(zhàn),入侵蘇聯(lián),發(fā)動(dòng)了歷史上規(guī)模最大的一場(chǎng)陸地戰(zhàn)役。希特勒自信能速戰(zhàn)速?zèng)Q,預(yù)計(jì)這一戰(zhàn)役不會(huì)超過3個(gè)月。他計(jì)劃采用征服了歐洲其余地區(qū)的閃電式戰(zhàn)略。入侵汁劃包含三大目標(biāo):向列寧格勒與莫斯科進(jìn)攻,并橫掃烏克蘭。
蘇聯(lián)領(lǐng)導(dǎo)人約瑟夫·斯大林被打了個(gè)措手不及,他指示全國人民在德國入侵者到來之前實(shí)行“焦土”政策。農(nóng)場(chǎng)和工廠被焚燒毀壞,或被弄得無法運(yùn)轉(zhuǎn)。在入侵的最初10個(gè)星期內(nèi),德國人一路東進(jìn)。俄國人傷亡人數(shù)多達(dá)一百多萬。
在北方,德國人包圍了列寧格勒。盡管忍受著極大困苦,列寧格勒的人民絕不投降。列寧格勒保衛(wèi)戰(zhàn)一直持續(xù)到冬季,此時(shí)該市的處境變得危急。由于食品匱乏.人們死于饑餓與疾病。到了1941年和1942年之間的寒冬,幾乎每天有4千人死于饑餓。列寧格勒之圍造成近百萬人死亡。
在俄國中部,希特勒的目標(biāo)是占領(lǐng)莫斯科。由于德國人指望速戰(zhàn)速?zèng)Q,他們沒有準(zhǔn)備過冬的補(bǔ)給。IO 月來臨,大雨不停?!澳酀魧④姟蓖涎恿说聡碎W電式進(jìn)攻的行動(dòng)。
正當(dāng)希特勒的軍隊(duì)逼近莫斯科時(shí),寒冷的冬季早早地降臨蘇聯(lián),那是多年不遇的嚴(yán)寒。氣溫降到攝氏零下48度。大雪紛飛。對(duì)俄國的嚴(yán)寒冬季毫無思想準(zhǔn)備的德國士兵身著單薄的夏裝,一個(gè)個(gè)被凍傷。德國人的坦克掩埋往深深的雪堆中。俄羅斯的冬季阻止了德國人的攻勢(shì)。
到1942夏天,希特勒又發(fā)起兩場(chǎng)新的攻勢(shì)。往南方,德國人占領(lǐng)了塞瓦斯托波爾。希特勒隨后向東推進(jìn)到斯大林格勒,那是沿伏爾加河綿延48公里的一座大工業(yè)城市。盡管艱苦卓絕,蘇聯(lián)抵抗者拒絕放棄斯大林格勒。
到1942夏天,希特勒又發(fā)起兩場(chǎng)新的攻勢(shì)。往南方,德國人占領(lǐng)了塞瓦斯托波爾。希特勒隨后向東推進(jìn)到斯大林格勒,那是沿伏爾加河綿延48公里的一座大工業(yè)城市。盡管艱苦卓絕,蘇聯(lián)抵抗者拒絕放棄斯大林格勒。
1942年11月,俄國人發(fā)起了一場(chǎng)反攻。德國軍隊(duì)在斯大林格勒城內(nèi)外幾乎沒有擋風(fēng)避寒的地方,食品和補(bǔ)給的匱乏更使其元?dú)獯髠?。直?943年1月德國人才放棄圍城。進(jìn)攻斯大林格勒的30萬德國人只剩下9萬忍饑挨餓的士兵。斯大林格勒一戰(zhàn)的失利最終使希特勒時(shí)乖運(yùn)蹇。部分地由于俄羅斯的冬季,德國人走向失敗了。
在1943年與1944年期間,蘇聯(lián)軍隊(duì)將德軍陣線往西逼退。在北方,1944年1月15日,紅軍發(fā)起突然襲擊,解除了列寧格勒長達(dá)3年之久的圍困。列寧格勒那些英勇無畏的幸存者看著入侵者在兩個(gè)早期內(nèi)全部撤離。到了1944年3月,烏克蘭的農(nóng)村又回到了蘇維埃手中。1944年5月9日,塞瓦斯托波爾從德國人手中被解放出來。至此,俄國人向柏林進(jìn)發(fā)。
就希特勒而言,對(duì)蘇聯(lián)的入侵成為一場(chǎng)軍事災(zāi)難。對(duì)俄羅斯人民來說,這場(chǎng)入侵帶來了無法形容的苦難。蘇維埃在第一次世界大戰(zhàn)中死亡的人數(shù)幾乎達(dá)到2千3百萬。
俄羅斯的冰雪衛(wèi)士
任何軍事行動(dòng)都必須考慮到自然的因素。拿破侖和希特勒都低估了俄羅斯冬季的嚴(yán)酷。冰雪和極低的氣溫使兩支侵略軍付出慘重的代價(jià)。對(duì)俄羅斯人民而言,嚴(yán)冬是他們的冰雪衛(wèi)上。? ? ? ? ? ? ? ?
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第二單元
智能汽車 課文A
能看、能聽,有知覺、具嗅覺、會(huì)說話的智能汽車?還能自動(dòng)駕駛?這聽起來或許像是在做夢(mèng),但計(jì)算機(jī)革命正致力于把這一切變?yōu)楝F(xiàn)實(shí)。
智能汽車
米基奧.卡庫
即便是過去70年間基本上沒有多少變化的汽車工業(yè),也將感受到計(jì)算機(jī)革命的影響。
汽車工業(yè)是20世紀(jì)最賺錢,最有影響力的產(chǎn)業(yè)之一。目前世界上有5億輛車,或者說每 lo人就有l(wèi)輛車。汽車工業(yè)的銷售額達(dá)一萬億美元左右,從而成為世界上最大的制造業(yè)。
汽車及其行駛的道路,將在主2l世紀(jì)發(fā)生重大變革。未來“智能汽車”的關(guān)鍵在于傳感器。我們會(huì)見到能看、能聽,有知覺,具嗅覺、會(huì)說話并能采取行動(dòng)的車輛與道路,”正在設(shè)計(jì)未來智能汽車和智能道路的通用汽車公司ITS項(xiàng)目的技術(shù)主任比爾·斯普雷扎預(yù)言道。
美國每年有大約4萬人死于交通事故。在汽車事故中死亡或嚴(yán)重受傷的人數(shù)太多,我們已經(jīng)不屑在報(bào)紙上提及。這些死亡的人中至少有半數(shù)是酒后開車者造成的,另外許多死亡事故是駕駛員不小心所導(dǎo)致。智能汽車能消除絕大多數(shù)這類汽車事故。它能通過會(huì)感測(cè)空氣中的酒精霧氣的電子傳感器撿測(cè)開車者是否喝醉酒,并拒絕啟動(dòng)引擎。這種車還能在遇竊后通報(bào)警方,告知車輛的確切地點(diǎn)。
能監(jiān)控行車過程以及周圍行車狀況的智能汽車已經(jīng)建造出來。藏在保險(xiǎn)杠里的微型雷達(dá)能對(duì)周圍的汽車作掃描。如果你發(fā)生重大行車失誤(如變道時(shí)有車輛在你“盲點(diǎn)”內(nèi)),計(jì)算衛(wèi)星從高空經(jīng)過時(shí)發(fā)出能被汽車卜計(jì)算機(jī)里的接收器辨認(rèn)的無線電信號(hào)。汽車上的計(jì)算機(jī)就會(huì)根據(jù)信號(hào)傳來所花的時(shí)間汁算出衛(wèi)星有多遠(yuǎn)。由于光速為人熟知,接收衛(wèi)星信號(hào)時(shí)的任何時(shí)間遲緩都能折算出距離的遠(yuǎn)近。
在日本,具有某種導(dǎo)航能力的汽車已有一百萬輛之多。(有些導(dǎo)航裝置通過將方向盤的轉(zhuǎn)動(dòng)與汽車在地圖上的位置并置來測(cè)定汽車的方位。)
隨著微芯片價(jià)格的大幅度下降,未來對(duì)全球衛(wèi)星定位系統(tǒng)的應(yīng)用幾乎是無限的?!爸圃爝@一商品的工業(yè)定會(huì)飛速發(fā)展,”生產(chǎn)導(dǎo)航系統(tǒng)的麥哲倫航儀公司的蘭迪·霍夫曼說。盲人可以在手杖里裝配全球衛(wèi)星定位系統(tǒng)傳感器,飛機(jī)可以通過遙控著陸,徒步旅行者可以測(cè)定自己在林中的方位——其潛在的應(yīng)用范圍是無止境的。
全球衛(wèi)星定位系統(tǒng)其實(shí)只是叫做“遠(yuǎn)程信息學(xué)”的這一更大行動(dòng)的一部分,這一行動(dòng)最終將把智能汽車送上智能高速公路。這種高速公路的樣品已經(jīng)在歐洲問世,加州也在進(jìn)行試驗(yàn),在高速公路上安裝計(jì)算機(jī)芯片、傳感器和無線電發(fā)射機(jī),以便向汽車報(bào)告交通擁擠堵塞情況。
在圣迭戈以北10英里的15號(hào)州際公路一段8英里長的路面上,交通工程師正在安裝一個(gè)由麻省理工學(xué)院設(shè)計(jì)的引進(jìn)“自動(dòng)司機(jī)”系統(tǒng)。這一計(jì)劃要求計(jì)算機(jī)在公路上埋設(shè)的數(shù)千
個(gè)3英寸長的磁釘?shù)膮f(xié)助下,在車輛極多的路段完全控制車輛的運(yùn)行。車輛會(huì)編成10輛或12輛一組,車距僅6英尺,在計(jì)算機(jī)的控制下一齊行駛。
這種計(jì)算機(jī)化的公路的倡導(dǎo)者對(duì)其未來的應(yīng)用充滿希望。到2010年,遠(yuǎn)程信息? ? ? ? ?
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? ? 技術(shù)很可能應(yīng)用于美國的一條主要公路。如果成功的話,到2020年,當(dāng)微芯片的價(jià)格降到一片一美分以下時(shí),遠(yuǎn)程信息技術(shù)就會(huì)應(yīng)用在美國成千上萬英里的公路上。這對(duì)環(huán)保也會(huì)很有利,能節(jié)省燃油,減輕交通阻塞,減少空氣污染污染,還可用作公路擴(kuò)建的替代辦法。
第三單元
求職面試
課文A
自己經(jīng)營公司的哈維麥凱經(jīng)常對(duì)求職者進(jìn)行面試。文中他告訴我們關(guān)于雇主看重 什幺樣品質(zhì)的秘密,并提出4點(diǎn)建議,幫助你顯得比眾人突出。
得到你想要的工作
哈維·B·邁克
我經(jīng)營著一家有350名左右員工的制造公司,我本人常常要對(duì)求職者進(jìn)行面試,決定是否聘用。我喜歡與可能成為營業(yè)員的人交談,因?yàn)樗麄儠?huì)是我們與顧客聯(lián)系的紐帶。
不久前一個(gè)新近畢業(yè)的大學(xué)生到我辦公室謀求一份銷售工作。我問他為這次面試做過哪些準(zhǔn)備。他說他在什么地方看到過有關(guān)本公司的些情況。
他有沒有給麥凱信封公司的人打過電話,好了解更多有關(guān)我們的情況?沒打過。他有沒有給我們的供應(yīng)廠商打過電話?還有我們的客戶?都沒有。
他可曾在就讀的大學(xué)里查問過有沒有校友在本公司就職,以便向他們了解一些情況’他可曾請(qǐng)朋友向他提問,對(duì)他進(jìn)行模擬面試?可曾去圖書館查找過有關(guān)本公司的剪報(bào)?
他事先有沒有寫封信來介紹自己,告訴我們自己為這次面試在做哪些準(zhǔn)備,自己何以能勝任此項(xiàng)工作?面試之后他是否打算再寫一封信,表明自己加盟本公司的誠意?這封信會(huì)不會(huì)在面試后的24小時(shí)之內(nèi)送到我們手上,也許甚至是親自送來?
他對(duì)上述每一個(gè)問題的回答全都一樣:沒有。這樣我就只剩一個(gè)問題要問了:如果此人代表本公司去見可能成為我們客戶的人,他準(zhǔn)備工作會(huì)做得怎樣?答案不言自明。在筆者看來,如欲被聘用,應(yīng)注意四個(gè)要訣:
1.準(zhǔn)備去贏。“一日不練,自己知道,”音樂家中自這樣的說法?!皟扇詹痪?,音樂評(píng)論家
知道。三日不練,觀眾知道?!?/p>
我們?cè)谟^看世界級(jí)音樂家或頂尖運(yùn)動(dòng)員的表演時(shí),看到的并不是使他們變成出類拔萃人物的長年苦練。世界上諸如邁克爾-喬丹這樣的頂尖人物無疑具有非凡才能,但他們?cè)谒{(lán)球場(chǎng)上也是第一個(gè)到,最后一個(gè)走。同樣的苦練適用于人類的各項(xiàng)活動(dòng)。若想被聘用,就要準(zhǔn) 備去贏。
我大學(xué)畢業(yè)時(shí),我極有可能終身從事同一個(gè)工作。當(dāng)時(shí)情況也的確如此。但如今已不再
是一生被聘去做一個(gè)工作了。指導(dǎo)就業(yè)的專家認(rèn)為.今天的大學(xué)畢業(yè)生在他們的生涯中可能
|會(huì)經(jīng)歷多達(dá)10次的職業(yè)變動(dòng)。
聽上去似乎壓力不小。然而,如果你作了準(zhǔn)備,壓力就是別人的——那些沒做準(zhǔn)備的人。
你不可能得到你想要的每份工作。最好的售貨員也不可能每次都成交。邁克爾喬丹投籃
命中率勉強(qiáng)過半。但認(rèn)真準(zhǔn)備一次面試的時(shí)間不會(huì)多于馬馬虎虎準(zhǔn)各五次面試的時(shí)間,而你
成功的可能性要多得多。
2永不中斷學(xué)習(xí)。最近我和一位90高齡的老者搭檔打雙人網(wǎng)球。我琢磨著那會(huì)是什么結(jié)局;可我的擔(dān)心是多余的。我們6:l擊敗對(duì)手。是6:1啊!
j
我們交換場(chǎng)地打第三局時(shí),他對(duì)我說“我打反手擊球你不介意吧?我向來喜歡多練練自
己的弱點(diǎn)。”好一個(gè)永不中斷學(xué)習(xí)的精彩實(shí)例。順便說一下,我們6:l贏 4 ?
? ? ? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ? ? 了第三局。
走出賽場(chǎng),我那90高齡的搭檔笑著說:“你也許想知道我在85歲以上年齡段的美國網(wǎng)球雙打排名第一!”他想的不是年屆90,想的甚至也不是85歲高齡。他想的是第一。
如果你努力克服自己的弱點(diǎn),發(fā)揮自己的優(yōu)勢(shì).你同樣可以做得那么好。要有能力競(jìng)爭(zhēng) 就得終生學(xué)習(xí)。
3.相信自己,那怕沒人相信你。還記得那4分鐘跑英里的往事嗎?幾百年來,運(yùn)動(dòng)員
們一直試圖實(shí)現(xiàn)這一目標(biāo),最終認(rèn)定人類的身體無法做到。我們的骨結(jié)構(gòu)不適應(yīng),我們的肺活量跟不上。
可是,有個(gè)人證明那些專家錯(cuò)了。奇跡中的奇跡是,在羅杰·班尼斯特打破4分鐘一
英里的紀(jì)錄6個(gè)星期之后,約翰-蘭迪又以幾乎快出整整2秒的成績打破了班尼斯特的紀(jì)錄。
此后,有大約800多名運(yùn)動(dòng)員打破了4分鐘一英里的記錄。
幾年前,我和女兒米米參加了紐約馬拉松比賽。發(fā)令槍一響.23,000名運(yùn)動(dòng)員沖出起跑線——最后有21,244名運(yùn)動(dòng)員到達(dá)終點(diǎn)。第一名是一位以2小時(shí)l1分鐘零1秒跑完全程的肯尼亞人。第21,244名運(yùn)動(dòng)員是一位越戰(zhàn)老兵。他用了3天9小時(shí)37分鐘跑完全程。沒有雙腿的他堅(jiān)持跑完了26.2英里。我和女兒在比賽的最初幾分鐘內(nèi)超過了他.當(dāng)時(shí)頓覺勇氣倍增,定要跑完全程。
別聽旁人說你不能實(shí)現(xiàn)自己的目標(biāo)。誰說你不比你的競(jìng)爭(zhēng)對(duì)手更堅(jiān)強(qiáng)、更努力、更能干?
要知道,所謂目標(biāo)就是有最后限期的夢(mèng)想:寫成文字,可測(cè)量,可確認(rèn),可實(shí)現(xiàn)。
4.想方設(shè)法顯得與眾不同。在我看來,紐約大多數(shù)的出租車司機(jī)即使不算無禮透頂.至
少也是不友好的。車輛大都十分骯臟,幾乎所有的車都觸目地裝有難以穿透的防彈隔離裝置。
可近日我在拉瓜迪亞機(jī)場(chǎng)跳上了一輛出租車,你猜怎么樣?車子竟然干干凈凈。放著優(yōu)美的音樂,而且沒有隔離裝置。
“請(qǐng)到帕克街酒店,”我對(duì)司機(jī)說。他笑容滿面地說:“你好,我叫沃利,”他說著遞給我一份保證書。一份保證書!上面寫著他將安全、札貌、準(zhǔn)時(shí)地將我送到目的地。
車開后,他拿出幾份報(bào)紙說:“請(qǐng)隨意翻閱?!彼€讓我隨意品嘗后座籃子里的水果。接著他又拿出手機(jī)說:“您要是想打電話,每分鐘1美元?!?/p>
我大吃一驚,脫口問道:“你這么做有多久了?”他回答說:“有三、四年了?!?/p>
“我知道不該問,”我說,“可是,你能多掙多少小費(fèi)?”
“一年12.000到14,000美元左右,”他得意地回答說。
他不知道他成了我心目中的英雄。他就是一個(gè)生動(dòng)的例證,說明你總是可以爭(zhēng)取到成功的機(jī)會(huì)。
我的良師益友柯特·卡爾森是明尼蘇達(dá)州的首富,擁有一家酒店和旅行社,營業(yè)收入約達(dá)90億美元。一次我要去紐約赴會(huì),柯特慷慨地請(qǐng)我乘坐他的私人飛機(jī)。碰巧那天明尼蘇達(dá)州遭受多年不遇的暴風(fēng)雪襲擊。明尼阿波利斯·圣保羅國際機(jī)場(chǎng)幾十年來第一次關(guān)閉。
? ? ?
雖然暴風(fēng)雪仍在肆虐,機(jī)場(chǎng)還是特地為小型飛機(jī)清出了一條跑道。我們正在跑道上滑行準(zhǔn)各起飛時(shí),柯特轉(zhuǎn)過頭來興奮地說:“看哪,哈維,雪地上沒有痕跡啊!”
柯特·卡爾森,當(dāng)時(shí)年屆70,富甲一方,竟然還會(huì)因?yàn)樽约菏堑谝粋€(gè)而如此興奮。
在我看來,這些正是關(guān)鍵之所在,準(zhǔn)備去贏。永不中斷學(xué)習(xí)。相信自己,哪怕沒人相信你。想方設(shè)法顯得與眾不同。然后就出發(fā),在雪地上留下你自己的足跡。
第三篇:英語課文翻譯
Unit 5PA奉告學(xué)子:教育是關(guān)鍵
比爾·蓋茨
每年都有數(shù)以百計(jì)的學(xué)生給我發(fā)電子郵件,要我就接受教育給他們提建議。他們想知道該學(xué)些什么,或者可不可以從大學(xué)輟學(xué),因?yàn)槲揖蜎]有讀完大學(xué)。
也有不少家長給我寫信,為子女尋求指導(dǎo)。他們問:“我們?cè)鯓硬拍馨押⒆右虺晒χ???/p>
我的基本忠告很簡(jiǎn)單,而且是發(fā)自內(nèi)心的:全力獲得最佳教育,充分利用高中和大學(xué),學(xué)會(huì)如何學(xué)習(xí)。不錯(cuò),為創(chuàng)建微軟,我未完成大學(xué)學(xué)業(yè),不過輟學(xué)之前我已經(jīng)在哈佛呆了三年,而且我真心希望有一天能重返校園。以前我也說過,誰也不應(yīng)該輟學(xué),除非他堅(jiān)信自己正面臨著一個(gè)一生僅有一次的機(jī)會(huì),但就算在那個(gè)時(shí)候也還是應(yīng)該深思熟慮。
Unit 6PA永不放棄
人們勸他引退,說他天分不夠,但是花樣滑冰選手保羅·懷利拒絕放棄。
1992年冬奧會(huì)閉幕后,保羅·懷利抵達(dá)華盛頓。走下飛機(jī)時(shí),歡迎的人群開始鼓掌。他差點(diǎn)停下了腳步。誰在后面呀?他心里嘀咕。雖說有銀牌在囊中,他怎么也不敢相信這掌聲是獻(xiàn)給他的。從那一刻起,保羅意識(shí)到自己的生活從此永遠(yuǎn)地改變了。
這位27歲的花樣滑冰運(yùn)動(dòng)員在法國的阿爾貝維爾獲得了銀牌,從此走向全新的生活。1988年的卡爾加里冬奧會(huì)上,他表現(xiàn)平平,只得了第10名,可如今他再也不是在大型賽事中舉止失措的無名小卒了;1991年的世界錦標(biāo)賽上,保羅比賽完后,裁判建議他退出冰壇,“給年輕選手讓位”,如今再也聽不到這樣的建議了。
Unit 7PA父親的教誨
三位成功人士講述父親怎樣塑造我們的人生。
瑞貝卡·洛伯:充滿愛心
自小我就知道,父親和母親深深相愛。只要單獨(dú)出門,他們總會(huì)吻別,我們兄妹幾個(gè)覺得挺肉麻的,可結(jié)婚時(shí),我卻滿心希望所找到的這個(gè)人,能像父親愛母親那樣愛著我。在我家,愛無處不在,我成長的過程很有安全感,真是妙不可言。
我上大學(xué)時(shí),母親在與乳腺癌作斗爭(zhēng)。父親自己憂心忡忡,卻是我們的精神支柱,對(duì)母親而言尤其如此。做了乳房切除術(shù)之后,母親決定不接受乳房再造術(shù),以免再受手術(shù)之苦,母親告訴我,在他們一起走過的日子里,父親甚至不曾叫她改變發(fā)型。相反,他總是對(duì)她說,她是多么的美麗動(dòng)人。正因?yàn)檫@樣,與癌癥作斗爭(zhēng),對(duì)她而言,倒也并不是多么可怕的事。她深知,不管發(fā)生什么事,父親和他的愛總是會(huì)和她在一起。
注:瑞貝卡·洛伯曾當(dāng)選全美“大學(xué)最佳球員”,曾是美國女子職業(yè)籃球協(xié)會(huì)的紐約自由女神隊(duì)球員。
理查德·布蘭森:鼓勵(lì)
我和幾個(gè)姐妹在英格蘭的一個(gè)小村莊長大。父親是個(gè)律師,為了生計(jì)而奔波,我卻一直就認(rèn)為他與眾不同。他從不指責(zé)我們,只是表揚(yáng),把我們的長處發(fā)揮出來。他會(huì)說:“給花澆水,花就會(huì)茂盛;不澆水,花就會(huì)死。”
我還記得我小的時(shí)候,說了別人幾句不好聽的話,父親便說,“說別人的壞話,反映的是你自身的品質(zhì)?!彼€解釋說,看到旁人的長處,別人也會(huì)看我的長處。我在經(jīng)營公司時(shí),一直盡量遵循這個(gè)原則。父親還一向通情達(dá)理。15歲那年,我辦了一本雜志,花了大量的時(shí)間,校長讓我自己作決定:要么繼續(xù)學(xué)業(yè),要么輟學(xué)去辦雜志。
約翰·路易斯:希望
小時(shí)候,我住在阿拉巴馬州的特洛伊,我經(jīng)常抱怨每天要起很早去農(nóng)場(chǎng)干活。一天,父親把我拉到一邊說:“孩子,我們這么做,也是為了日子好過呀。堅(jiān)持一下,情況總會(huì)好起來的。”
父親生性樂觀,對(duì)未來滿懷希望,這種態(tài)度對(duì)我有潛移默化的影響。他還教導(dǎo)我們說,我們不能只顧自己,還應(yīng)該關(guān)心別人。
在我看來,父親總是在奉獻(xiàn),在分享。我們自己條件也不寬裕,沒有很多可供奉獻(xiàn)或分享,但父親堅(jiān)信,一切都會(huì)好的,即使在極其艱難的條件下也會(huì)如此。當(dāng)年阿拉巴馬有許多事情令人可怕:種族隔離很厲害;我們用的噴泉式飲水器上面標(biāo)著“黑人使用”字樣;上街時(shí)我們只能走街道的一邊。但他挺過了這一切,沒有怨,沒有怒,沒有憎。
Unit 8PA你是最薄弱的環(huán)節(jié),再見
還記得美好的往日時(shí)光嗎?在那樣的純真年代,我們共享文檔和可執(zhí)行文件,根本沒有半點(diǎn)顧慮。不錯(cuò),每隔一個(gè)月左右你可能會(huì)碰到一個(gè)引導(dǎo)扇區(qū)病毒,不過這些很容易對(duì)付,就算殺毒軟件沒有把它查出來也不要緊。
那些長長的夏日,悠閑自得,可惜消逝得太快。宏病毒使IT管理者們迅速成長起來,他們意識(shí)到有的病毒能迅速擴(kuò)散到整個(gè)機(jī)構(gòu)。一家公司里的數(shù)百臺(tái)計(jì)算機(jī)感染了通過電子郵件附件傳播的病毒,也是十分平常的事。公司各部門中身體最好的當(dāng)屬IT員工,因?yàn)樗麄儽甲哂诟髋_(tái)計(jì)算機(jī)之間,清理病毒。
防病毒得想個(gè)更好的辦法才行。各家公司現(xiàn)在都意識(shí)到病毒并不是“現(xiàn)代神話”,而確實(shí)會(huì)嚴(yán)重影響到公司的運(yùn)作。他們投資殺毒軟件,安裝在計(jì)算機(jī)、服務(wù)器以及電子郵件網(wǎng)關(guān)上,甚至還采取措施確保使用最新的檢查程序,隨時(shí)更新殺毒軟件。
聽起來好像各公司已經(jīng)采取了充分的措施防范病毒??墒聦?shí)真的如此嗎?
第四篇:英語課文及翻譯專題
英語課文及翻譯
第一單元
第三段 成名者之所以成名,大多是因?yàn)榘l(fā)揮了自己在歌唱、舞蹈、繪畫或?qū)懽鞯确矫娴奶亻L,并能形成自己的風(fēng)格。
為了能迅速走紅,代理人會(huì)極力吹捧他們這種風(fēng)格。他們青云直上的過程讓人看不清楚。
他們究竟是怎么成功的,大多數(shù)人也都說不上來。
盡管如此,藝術(shù)家仍然不能閑下來。
若表演者、畫家或作家感到無聊,他們的作品就難以繼續(xù)保持以前的吸引力,也就難以保持公眾的注意力。
公眾的熱情消磨以后,就會(huì)去追捧下一個(gè)走紅的人。
有些藝術(shù)家為了不落伍,會(huì)對(duì)他們的寫作、跳舞或唱歌的風(fēng)格稍加變動(dòng),但這將冒極大的失寵的危險(xiǎn)。
公眾對(duì)于他們藉以成名的藝術(shù)風(fēng)格以外的任何形式都將不屑一顧。
第九段
對(duì)那些孤注一擲的追名逐利之徒,我要說:祝你們好運(yùn)。
但是,遺憾的是,你會(huì)發(fā)現(xiàn)這不是你想得到的。
狗自逐其尾所得到的只是一條尾巴而已。
獲得成功的人常常發(fā)現(xiàn)成功對(duì)他來說弊大于利。
所以要為真實(shí)的你、為自己的所為感到高興,而不是拼命去獲得成功。
做那些你為之感到驕傲的事情。
可能在有生之年你默默無聞,但你可能創(chuàng)作了更好的藝術(shù)。
第二單元
第四段
事實(shí)上,當(dāng)卓別林再也無法抵制有聲電影,不得不為他的“流浪漢”尋找“合適的聲音”時(shí),他確實(shí)很頭疼。
他盡可能地推遲那一天的到來:在 1936 的《摩登時(shí)代》里,他第一次在影片里發(fā)聲唱歌。在片中,他扮演一名侍者,滿口胡言亂語,聽起來不像任何國家的語言。
后來他說,他想象中的“流浪漢”是一位受過大學(xué)教育,但已經(jīng)沒落的紳士。
但假如他在早期那些短小的喜劇電影中能操一口受教育人的口音,那么他是否會(huì)聞名世界就難說了,而英國人也肯定會(huì)覺得這很“古怪”。沒有人知道卓別林這么干是不是有意的,但這促使他獲得了巨大的成功。
第四單元
第四段 然而毋庸?fàn)庌q,通信技術(shù)將是區(qū)分輸贏的關(guān)鍵因素。
看一看俄羅斯的情況吧。
由于其堅(jiān)實(shí)的數(shù)學(xué)和科學(xué)教育基礎(chǔ),它應(yīng)該在信息時(shí)代有繁榮的發(fā)展。
問題是,它的國內(nèi)電話系統(tǒng)是一堆生銹的20世紀(jì)30年代的老古董。
為了解決這一問題,俄羅斯已經(jīng)開始鋪設(shè)光纖電纜,并制定了投入400億美元建設(shè)多項(xiàng)通信工程的戰(zhàn)略計(jì)劃。
但是由于其經(jīng)濟(jì)陷于低迷,幾乎沒有資金來著手解決最基本的問題。
第五段
與俄羅斯相比,在未來10年中,中國大陸計(jì)劃對(duì)通信設(shè)備投入1,000億美元。
從某種意義上說,中國的落后成了一種有利因素,因?yàn)檫@一發(fā)展正好發(fā)生在新技術(shù)比銅線電纜系統(tǒng)更便宜的時(shí)候。
到1995年底,中國除了拉薩以外的省會(huì)都將有數(shù)字轉(zhuǎn)換器和高容量的光纖網(wǎng),這意味著其主要城市正在具備必需的基礎(chǔ)設(shè)施,成為信息高速公路的主要部分,使人們能夠進(jìn)入系統(tǒng),獲得最先進(jìn)的服務(wù)。
第六單元
第三段
高尚的道德標(biāo)準(zhǔn)說起來容易,但實(shí)際上人們?cè)谶@種情況下究竟會(huì)怎么做呢?
早些時(shí)候,一家英國汽車制造商被指控利用一筆基金行賄,并進(jìn)行其他一些可疑運(yùn)作,如給代理商和客戶高額回扣、提供額外折扣、向一些在瑞士銀行開的匿名賬戶匯款等。
這家汽車公司否認(rèn)了這些指控,后來指控也被撤銷了。
然而,當(dāng)時(shí)英國汽車業(yè)里就有人準(zhǔn)備私下里說:“瞧,我們這一行競(jìng)爭(zhēng)激烈,每年我們汽車的海外銷售額超過10億英鎊。
如果花幾百萬英鎊能讓一些客戶高興,誰會(huì)有損失呢?
我們不這樣干,別人也會(huì)這樣干的。
第八單元
第五段
身邊總有人提醒我自己是奴隸的后代,但這并沒有使我沮喪。
奴隸制是60年前的事了。
解放黑奴的這場(chǎng)手術(shù)很成功,病人的情況也不錯(cuò),謝謝。
這場(chǎng)使我從黑奴變?yōu)槊绹竦目膳聭?zhàn)爭(zhēng)喊道“各就位!”
內(nèi)戰(zhàn)后的那段時(shí)期說“預(yù)備!”我的上一代人則喊“跑!”
就像一場(chǎng)賽跑一樣,我飛速起跑,決不可中途停步,傷心回望。
身為黑奴是我為文明生活所付出的代價(jià),而作出這一選擇的并不是我。
世界上再?zèng)]有什么人有過比這更大的爭(zhēng)取榮耀的機(jī)會(huì)了。
想想將要獲得的新生活,而且我們不會(huì)有任何損失。不管我做什么,都可能得到雙倍的嘉獎(jiǎng),或是雙份的責(zé)難。想想這一點(diǎn),知道這一點(diǎn)都令人激動(dòng)不已。
占據(jù)國內(nèi)舞臺(tái)的中心可真刺激,而臺(tái)下的觀眾則不知是喜是憂。
第十單元
第三段
《時(shí)代周刊》最近的封面故事列舉了目前關(guān)于智能的一些看法,報(bào)道說:“新的人腦研究表明,衡量人的智能的真正尺度可能是情感,而不是智商?!?/p>
《時(shí)代周刊》稱之為“情商”的情感智能的根本意義可從企業(yè)管理專家卡倫?波爾斯頓的話中窺見一斑:“顧客對(duì)企業(yè)說?我可不在乎是否你的每個(gè)員工都畢業(yè)于哈佛,我只愿意與能理解我、尊重我的企業(yè)打交道。?”
第八段
綜合考慮他人的看法。
大腦研究表明,人們對(duì)外界的看法受到遺傳基因及個(gè)人經(jīng)歷的局限。
學(xué)會(huì)吸納他人有用的觀點(diǎn)是一種擴(kuò)大自己見識(shí)的方式。
下次如果有人對(duì)某件事與你有不同的看法,比如對(duì)某個(gè)有爭(zhēng)議的政治事件,停下來想想這其實(shí)是生活閱歷使然,應(yīng)把它看作一種感知能力的饋贈(zèng)。
第五篇:英語課文翻譯
Unit 1 Section A 我哥哥吉米出生時(shí)遇上難產(chǎn),因?yàn)槿毖鯇?dǎo)致大腦受損。兩年后,我出生了。從此以后,我的生活便圍繞我哥哥轉(zhuǎn)。伴隨我成長的,是“到外面去玩,把你哥哥也帶上?!辈粠纤?,我是哪里也去不了的。因此,我慫恿鄰居的孩子到我家來,盡情地玩孩子們玩的游戲。我母親教吉米學(xué)習(xí)日常自理,比如刷牙或系皮帶什么的。我父親宅心仁厚,他的耐心和理解使一家人心貼著心。我則負(fù)責(zé)外面的事,找到那些欺負(fù)我哥哥的孩子們的父母,告他們的狀,為我哥哥討回公道。父親和吉米形影不離。他們一道吃早飯,平時(shí)每天早上一道開車去海軍航運(yùn)中心,他們都在那里工作,吉米在那搬卸標(biāo)有彩色代號(hào)的箱子。晚飯后,他們一道交談,玩游戲,直到深夜。他們甚至用口哨吹相同的曲調(diào)。所以,父親1991年因心臟病去世時(shí),吉米幾乎崩潰了,盡管他盡量不表現(xiàn)出來。他就是不能相信父親去世這一事實(shí)。通常,他是一個(gè)令人愉快的人,現(xiàn)在卻一言不發(fā),無論說多少話都不能透過他木然的臉部表情了解他的心事。我雇了一個(gè)人和他住在一起,開車送他去上班。然而,不管我怎么努力地維持原狀,吉米還是認(rèn)為他熟悉的世界已經(jīng)消失了。有一天,我問他:“你是不是想念爸爸?”他的嘴唇顫抖了幾下,然后問我:“你怎么看,瑪格麗特?他是我最好的朋友?!苯又覀z都流下了眼淚。六個(gè)月后,母親因肺癌去世,剩下我一人來照顧吉米。吉米不能馬上適應(yīng)去上班時(shí)沒有父親陪著,因此搬來紐約和我一起住了一段時(shí)間。我走到哪里他就跟到哪里,他好像適應(yīng)得很好。但吉米依然想住在我父母的房子里,繼續(xù)干他原來的工作。我答應(yīng)把他送回去。此事最后做成了。如今,他在那里生活了11年,在許多人的照料下,同時(shí)依靠自己生活得有聲有色。他已成了鄰里間不可或缺的人物。如果你有郵件要收,或有狗要遛,他就是你所要的人。當(dāng)然,母親的話沒錯(cuò):可以有一個(gè)家,既能容納他的缺陷又能裝下我的雄心。事實(shí)上,關(guān)照像吉米這樣一個(gè)深愛又感激我的人,更加豐富了我的生活,其他任何東西都不能與之相比。這一點(diǎn),在9·11災(zāi)難后幾天更顯真切。那天是吉米57歲生日。我在紐約自己的家里為他舉辦生日宴會(huì),但是我們家的人都沒能來參加,因?yàn)榻煌ɡщy,而且災(zāi)難帶來的恐懼使他們依然心有余悸。我邀請(qǐng)了我的好友,請(qǐng)他們來幫忙把宴會(huì)弄得熱鬧些,增加點(diǎn)歡快氣氛,沒去理會(huì)他們多數(shù)人在情感上都有些疲憊這一事實(shí)。于是我一反常態(tài),沒說“請(qǐng)不要帶禮物”,而是向他們喊“請(qǐng)帶禮物來”。我的朋友──吉米認(rèn)識(shí)他們多年了──帶來了中意的禮物:鄉(xiāng)村音樂CD、一件長袖運(yùn)動(dòng)衫、一條有“吉米”字樣的皮帶、一頂編織的羊毛帽,還有一套牛仔服。那天晚上,我們先是送禮物,然后是切從他喜歡的面包店里買來的巧克力蛋糕,當(dāng)然還唱了“生日歌”,否則宴會(huì)就不算完整了。吉米一次次地問:“該切蛋糕了吧?”等用完餐和送完禮物后,吉米再也控制不住了。他焦急地等著點(diǎn)上蠟燭,然后在我們“生日快樂”的歌聲中,一口長氣吹滅了蠟燭。戶然而吉米對(duì)我們的努力還是感到不滿足。他縱身跳到椅子上,直挺著身子,雙手食指朝天,一邊喊一邊指揮我們唱歌:“再──來──次!”我們?nèi)σ愿暗爻?。待我們唱完時(shí),他翹起兩個(gè)拇指喊道:“好極了!”本來我們想讓他知道,無論世上有多難的事情,總是有人來關(guān)心他。現(xiàn)在反倒是提醒了我們自己。對(duì)于吉米來說,我們唱歌時(shí)的愛心,是他心中額外的禮物,但是他原先更想看到的,是別人再次感到快樂。有如父親的去世一夜之間改變了吉米的世界,9·11也改變了我們的生活;我們熟悉的世界不復(fù)存在了。但是,當(dāng)我們?yōu)榧壮?,相互緊擁,祈禱全球和平時(shí),我們也意識(shí)到,朋友、家人間永恒的愛和支持可以讓我們克服生活中的任何困難。吉米以樸素的方式為我們協(xié)調(diào)了眼前的一切,他做到這一點(diǎn)并不令人吃驚。吉米的愛可以征服一切,這是任何東西都限制不了的。
Unit 4 sectionA
自由女神像
19世紀(jì)70年代中期,法國藝術(shù)家弗里德里克·奧古斯特·巴托爾迪正在設(shè)計(jì)一個(gè)大項(xiàng)目,名為“自由照耀世界”。這是一座慶祝美國獨(dú)立和美法聯(lián)盟的紀(jì)念碑。
與此同時(shí),他愛上了一位他在加拿大認(rèn)識(shí)的女子。他母親不贊成自己的兒子和一個(gè)她沒有見過的女子戀愛,然而巴托爾迪不為所動(dòng),和心中所愛于1876年結(jié)為伉儷。
同年,巴托爾迪組裝完雕像的右臂和火炬,并將它們陳列在費(fèi)城。
據(jù)說,他用了妻子的手臂為模本,但覺得她的臉太漂亮,不適合做雕像模本。
他需要這樣一個(gè)女人:面容滄桑卻不失堅(jiān)定,莊重多于美麗。
他選擇了自己的母親。1886年,自由女神像在紐約灣北部落成。
雕像綜合了他母親的臉和他妻子的身材,不過巴托爾迪稱之為“我的女兒,自由之神”。
芭比娃娃
在現(xiàn)今銷售的各式各樣的芭比娃娃之前,原本部門只有一種芭比娃娃。
實(shí)際上,她的名字叫芭芭拉。
芭芭拉·漢德勒是馬特爾玩具公司的聯(lián)合創(chuàng)始人艾略特和魯思·漢德勒夫婦的女兒。
魯思是在見到女兒玩紙娃娃之后才想到做芭比娃娃的。
芭比娃娃的三維模特是一個(gè)德國洋娃娃,一個(gè)哄成年人開心的禮物,被描繪成具有“風(fēng)塵女子”的模樣。
馬特爾公司將這個(gè)娃娃做了一番改造,變成了體面而地道的美國版本,盡管胸圍有些夸張。它以當(dāng)時(shí)10多歲的少女芭芭拉的名字命名。
自從1959年面世,芭比娃娃就成了全球公認(rèn)的“娃娃女王”。
馬特爾公司說,一般的美國女孩擁有10個(gè)芭比娃娃,全球每秒鐘就有兩個(gè)芭比娃娃售出。
如今芭芭拉已有60多歲了,她拒絕接受采訪,但據(jù)說她非常喜歡芭比娃娃。她可能是當(dāng)今世上最著名的不為人知的人物了。1961年,芭比娃娃的男朋友面世,按芭芭拉的弟弟肯的名字命名。
真正的肯于1994年去世。他對(duì)令自己全家名揚(yáng)天下的娃娃極為厭惡。
他在1993年說:“我可不想讓我的孩子玩這洋娃娃?!?/p>
《美國哥特人》
1930年,格蘭特·伍德因其畫作《美國哥特人》一舉成名。此畫體現(xiàn)了美國農(nóng)民莊嚴(yán)的自豪,常常被人復(fù)制。
畫面展示了一位神色嚴(yán)肅的男子和一位女子站立在農(nóng)舍之前。
伍德深受中世紀(jì)藝術(shù)家的影響,他的靈感來自于一所古老農(nóng)舍的哥特式窗戶,但最令世界注目的是畫中人物的臉。
伍德喜歡畫他熟悉的臉。為畫神色嚴(yán)肅的農(nóng)夫,他選擇了他那表情木訥的牙醫(yī),至于站在他身邊的農(nóng)婦,他選擇了自己的姐姐南。他把模特的脖子稍稍畫長了一些,但無疑能看出誰是畫像的原型。
南后來說道,《美國哥特人》帶給她的名譽(yù)使她擺脫了一種非常乏味的生活。
野牛鎳幣今天,美國的硬幣都用來紀(jì)念美國政府的杰出人物,其中大部分是著名的前總統(tǒng)。
但1913至1938年間發(fā)行的野牛鎳幣,卻是為了紀(jì)念由美國拓居引起的兩起相互關(guān)聯(lián)的悲劇──野牛群的滅絕和美洲印第安人的毀滅。此前一直是白人被用作美國鎳幣上的模特,而著名的藝術(shù)家詹姆斯·厄爾·弗雷澤卻反傳統(tǒng)而行之,起用了三名真正的美洲印第安人作為自己創(chuàng)作的原型。由于大草原上不再有野牛漫步,弗雷澤為了鎳幣另一面上的野牛,只好到紐約中央公園的動(dòng)物園里素描一只老野牛。兩年后,即1915年,此牛以100美元的價(jià)格售出,然后被宰殺取肉、剝皮,牛角制成了墻上的裝飾品。
山姆大叔
美國獨(dú)立戰(zhàn)爭(zhēng)時(shí)期,14歲的山姆·威爾遜離家出走,加入父親和哥哥們的行列,為美國殖民地獨(dú)立于英國而戰(zhàn)。
23歲時(shí),他開始從事肉類加工業(yè),并因?yàn)槿苏\實(shí)、工作勤奮而贏得聲譽(yù)。
此后在1812年的戰(zhàn)爭(zhēng)中,威爾遜獲得了一個(gè)職位,為美國軍隊(duì)檢驗(yàn)肉食。他的合伙人和美國政府簽訂了一份合同,給軍隊(duì)提供肉食。送到軍隊(duì)的肉桶上面都印有EA-US標(biāo)志,EA代表公司名,US代表原產(chǎn)國。
傳說有一回,有個(gè)政府官員來參觀加工廠,問及這些字母的含義,一個(gè)想象力豐富的雇員告訴他,“US”是“山姆大叔”威爾遜的縮寫。很快,士兵們都說所有的軍需品都來自“山姆大叔”。戰(zhàn)后,政治漫畫里開始出現(xiàn)一個(gè)名叫“山姆大叔”的人物。他的原型是一個(gè)早期漫畫人物,名叫喬納森大哥,此人在美國獨(dú)立戰(zhàn)爭(zhēng)時(shí)期非常出名。
很快,山姆大叔就取代了喬納森大哥,成了最受美國人歡迎的象征。
最令人難忘的山姆大叔的畫像是由畫家詹姆斯·蒙哥馬利·弗拉格創(chuàng)作的,用在兩次世界大戰(zhàn)期間他畫的很多著名的征兵招貼畫上。山姆大叔的形象是:高個(gè)子,白頭發(fā),下巴上有一小撮白胡子,身著深藍(lán)色外套,頭戴一頂高帽,上有星星點(diǎn)綴。這模樣其實(shí)就是弗拉格的自畫像。Unit 2
運(yùn)動(dòng)醫(yī)學(xué)專家經(jīng)過多年的觀察,發(fā)現(xiàn)耐力運(yùn)動(dòng)員,特別是女性,經(jīng)常會(huì)缺鐵。普渡大學(xué)研究人員進(jìn)行的一項(xiàng)新的研究表明:即使是適度的鍛煉,也可能會(huì)降低女性血液中的鐵含量?!拔覀儼l(fā)現(xiàn),那些通常不運(yùn)動(dòng)的女性一旦開始適度的鍛煉,就會(huì)出現(xiàn)鐵含量下降的跡象,”普渡大學(xué)羅斯安妮· M.萊爾副教授說。她對(duì)62 名婦女進(jìn)行了研究,并將研究結(jié)果發(fā)表在《體育運(yùn)動(dòng)醫(yī)學(xué)與科學(xué)》雜志上。這些婦女原先不怎么運(yùn)動(dòng),后來開始了為期6個(gè)月、每周3次的鍛煉。萊爾指出:“那些增食肉類食品或服用鐵質(zhì)補(bǔ)劑的女性能夠恢復(fù)到健康狀態(tài)。
但突然參加鍛煉卻仍沿用舊食譜的人則顯示出鐵含量降低。”缺鐵在女性中是很常見的,每四個(gè)十幾歲的少女中有一人缺鐵,每五個(gè)18至45歲的女性中有一人缺鐵。而在積極鍛煉的婦女中這一比例更高,女耐力運(yùn)動(dòng)員中,缺鐵者比例則高達(dá)80%。萊爾說,這意味著 “太多女性忽視了自己攝入的鐵含量”。育齡女性危險(xiǎn)最大,因?yàn)樵陆?jīng)是鐵流失的重要原因之一。此外,許多保健意識(shí)太強(qiáng)的女性也很危險(xiǎn),因?yàn)樗齻兙芙^食用牛肉或羊肉,而這些肉中含有的鐵最易被吸收。而且,由于女性常常為了控制體重而節(jié)食,從而未能攝取足夠的含鐵豐富的食物,結(jié)果可能導(dǎo)致缺鐵。另一名專家指出,“普通女性每天攝入的鐵只是應(yīng)攝入量的三分之二?!彼赋?,“對(duì)于那些已經(jīng)缺鐵的女性,任何因鍛煉而產(chǎn)生的更多鐵質(zhì)流失都足以導(dǎo)致體內(nèi)缺鐵狀況的惡化?!边\(yùn)動(dòng)可能通過多種機(jī)制導(dǎo)致鐵流失。有些鐵隨汗液流失。另外,由于某些未知的原因,高強(qiáng)度的耐力運(yùn)動(dòng)有時(shí)會(huì)引起消化系統(tǒng)內(nèi)出血。運(yùn)動(dòng)員從事跑步之類高強(qiáng)度劇烈運(yùn)動(dòng),也可能會(huì)因?yàn)樽悴垦苁а默F(xiàn)象而使鐵質(zhì)流失。缺鐵分為三個(gè)階段:第一也即最常見的階段,是鐵質(zhì)儲(chǔ)量不足。這一階段一般沒有癥狀。到了缺鐵的第二階段,就會(huì)出現(xiàn)疲倦和力不從心,此時(shí)體內(nèi)已沒有足夠的鐵來形成血蛋白分子,將氧輸至運(yùn)動(dòng)肌肉。在第三即最后階段,人常常感到虛弱、疲乏無力、喘不過氣,運(yùn)動(dòng)成績大打折扣?!叭藗冋J(rèn)為,只要不到第三階段就不會(huì)有什么問題。這種想法是不對(duì)的?!睅椭O(shè)計(jì)普渡大學(xué)研究的約翰·L.比爾德說?!爸挥挟?dāng)你的鐵儲(chǔ)量為零時(shí),你才會(huì)進(jìn)入第三階段。而你若坐等到這個(gè)時(shí)候,你的麻煩就大了?!比欢?,比爾德指出,大多數(shù)鐵質(zhì)儲(chǔ)量低的人并未意識(shí)到自己缺鐵,因?yàn)閭鹘y(tǒng)的檢測(cè)血液中鐵含量的方法──檢驗(yàn)血液中輸送氧氣的血蛋白的含量──是不夠的。其實(shí),有必要檢查血液中另一種混合成分的含量,它可以顯示血液中的鐵含量。他還指出,雖然積極鍛煉的育齡婦女最有可能鐵含量低,“但男性也并非不缺鐵,尤其是在他們不吃肉類而又從事高強(qiáng)度的體力活動(dòng)的情況下?!保ü烙?jì)有 15%的男性長跑運(yùn)動(dòng)員鐵含量低。)比爾德和其他專家都說,對(duì)這些人而言,最好每年驗(yàn)一次血,以測(cè)定血液中的鐵含量。如果鐵含量低,就要去看醫(yī)生,以確定是否該通過調(diào)整飲食或服用鐵質(zhì)補(bǔ)劑來校正不足。一般說來,解決問題的最好方法是在食譜中增加含鐵豐富的食物,因?yàn)殍F質(zhì)補(bǔ)劑可能存在嚴(yán)重缺陷?!胺描F質(zhì)補(bǔ)劑可能使人想嘔吐,有時(shí)甚至還會(huì)引起中毒。最好的鐵來源,以及唯一最易為身體所吸收的鐵來源,是肉、雞和魚。其他較好的鐵質(zhì)來源包括棗、豆類和一些多葉綠色蔬菜?!薄斑x擇那些標(biāo)有?加鐵?字樣的面包和麥片,”運(yùn)動(dòng)營養(yǎng)專家南?!た死藢懙溃斑@些增加的鐵質(zhì)補(bǔ)充了谷物中自然含鐵量的不足。將這些食物與含有大量維生素
C的食物一起食用──比如吃麥片時(shí)喝橘子汁,或在三明治內(nèi)夾上番茄──可以促進(jìn)鐵質(zhì)吸收?!笨死诉€建議用鐵鍋烹食,因?yàn)榕胝{(diào)過程中食物能從鐵鍋中吸收鐵質(zhì)。她寫道,“在鐵鍋內(nèi)烹煮了
3個(gè)小時(shí)的番茄汁,其鐵含量大大提高,增加到原來的30倍左右?!彼f,鐵含量可能低的人,吃飯時(shí)應(yīng)避免喝咖啡或飲茶,因?yàn)檫@些飲料中所含的物質(zhì)會(huì)妨礙身體對(duì)鐵質(zhì)的吸收?!斑\(yùn)動(dòng)女性應(yīng)特別注意選擇飲食?!逼斩纱髮W(xué)的萊爾總結(jié)說:“如果你在鐵含量流失之前就注意到了警告信號(hào),你就可以在它真正成為問題之前彌補(bǔ)鐵質(zhì)的不足?!?/p>
第六單元 人如其名
在她人生最初的24年里,人們一直叫她戴比──一個(gè)和她的漂亮容貌和優(yōu)雅舉止不相配的名字?!拔业拿挚偸鞘刮矣X得自己應(yīng)該是一個(gè)廚子,”她抱怨道“我真的不想要戴比這個(gè)名字。”
一天,在填寫一份出版工作職位的申請(qǐng)表時(shí),這位小姐一時(shí)沖動(dòng),用她的中名林恩替換了她的名字戴比?!斑@是我一生中干得最漂亮的一件事,”現(xiàn)在她對(duì)人這樣說,“一旦我不再稱自己為戴比,我就感到好多了?? 而且其他人也開始更認(rèn)真地對(duì)待我了?!表樌赝ㄟ^那次工作面試兩年后,這位昔日的女服務(wù)員現(xiàn)在成了一位成功的雜志編輯。朋友和同事們都叫她林恩。
當(dāng)然,戴比(或林恩)的職業(yè)成就并不是改名帶來的,但是這肯定給她帶來了好處,雖說改名僅使她對(duì)自己的才能增加了一點(diǎn)點(diǎn)自信。社會(huì)科學(xué)家認(rèn)為你叫什么名字會(huì)影響你的生活。從古至今,名字不僅被用來識(shí)別人,而且也被用來描述人?!妒ソ?jīng)》上說:人如其名。此外,《韋伯斯特大詞典》也對(duì)名字作了如下的定義:表達(dá)某種特點(diǎn)的一個(gè)或幾個(gè)字,這種特點(diǎn)被認(rèn)為反映了某人或某事的本質(zhì),或描述了某人某事,常表示嘉許或不贊成的意思。請(qǐng)好好注意這幾個(gè)詞:“嘉許或不贊成”。不管是好是壞,諸如友好或拘謹(jǐn)、相貌平平或漂亮嫵媚等特征已經(jīng)在你的名字中有所暗示,甚至他人在見到你本人之前就已經(jīng)知道你的這些特征了。
名字是與特定形象相關(guān)聯(lián)的,任何一個(gè)被稱為“相貌平常的簡(jiǎn)”或“普普通通的喬”的人都能證明這一點(diǎn)。后面的那個(gè)名字特別使我煩惱,因?yàn)槲乙步袉獭S行┤苏J(rèn)為這個(gè)名字使我更適合于做一名棒球運(yùn)動(dòng)員而不是別的什么職業(yè),比如說藝術(shù)評(píng)論家。然而,盡管有此局限,我確實(shí)曾一度設(shè)法成為了一名藝術(shù)評(píng)論家。即便如此,一家著名雜志一直拒絕把“喬”作為我的文章署名,而是用我名字的首字母 J.S.來代替。我懷疑,假如我的名字是比較文雅的阿瑟或艾德里安的話,我的名字早已完整地出現(xiàn)在雜志上了。
當(dāng)然,有積極含義的名字對(duì)你是有好處的,甚至能促進(jìn)你結(jié)交新朋友。最新調(diào)查表明:美國男士認(rèn)為蘇珊是最有吸引力的女性名字,而女士則認(rèn)為理查德和戴維是最有吸引力的男性名字。我認(rèn)識(shí)一位女士,她就拒絕了一次與一位叫哈里的男人見面,因?yàn)椤斑@人的名字聽上去沒勁”。可就在幾天后的一個(gè)晚間聚會(huì)上,她走到我身邊,催我把她介紹給一位氣度不凡的男人;他們倆人整個(gè)晚上都在互送秋波?!芭?,”我說:“你指的是哈里呀?!彼犃撕蟾械胶軐擂巍?/p>
雖然我們中大多數(shù)人會(huì)認(rèn)為自己沒有這樣的偏見,但在某種程度上,我們都多多少少對(duì)名字產(chǎn)生過成見。說實(shí)話,你碰到一個(gè)名叫奈杰爾的木匠會(huì)不會(huì)感到驚訝呢?或是一個(gè)叫伯莎的物理學(xué)家?抑或是一個(gè)叫梅爾的教皇?正如我的一位女性朋友在照看托兒所里四歲的兒童時(shí)所發(fā)現(xiàn)的那樣,我們常常把由名字引起的固有想法加到他人身上?!霸谕袃核?,有一次我想讓一個(gè)很活躍的名叫朱利安的小男孩靜靜地坐下來看書,而把一個(gè)喜歡沉思、名叫羅里的孩子推出去打球。因?yàn)樗麄兊拿?,我把他們的性格給搞混了!”
很明顯,這樣的偏見也會(huì)影響課堂成績。在一項(xiàng)由圣迭戈州立大學(xué)的赫伯特·哈拉里及喬治亞州立大學(xué)的約翰·麥克戴維主持的研究中發(fā)現(xiàn),教師總是給署名為埃爾默和休伯特的作文打較低的分?jǐn)?shù),但當(dāng)把這兩篇作文的署名改為邁克爾和戴維時(shí),老師給的分?jǐn)?shù)就要高些。但是教師的偏見不是造成課堂成績差別的唯一原因。坦普爾大學(xué)的托馬斯·V·布塞博士和路易莎·瑟拉里達(dá)里安發(fā)現(xiàn):那些名叫琳達(dá)、黛安、芭芭拉、卡羅爾及辛迪之類的女孩們?cè)谠u(píng)分較客觀的智力測(cè)驗(yàn)和學(xué)業(yè)成績測(cè)驗(yàn)中的表現(xiàn)比那些名字不太有吸引力的女孩要好。(一個(gè)與之相關(guān)的研究表明:女孩受同伴歡迎的程度也與她們的名字受歡迎的程度有關(guān)系,雖然對(duì)男孩來說這種關(guān)系不太明顯。)
雖然你父母很可能想讓你的名字伴隨你一輩子,但記住,他們選這個(gè)名字的時(shí)候幾乎還沒有見到你呢。而且,他們?cè)谶x名字時(shí)所看重的希望和夢(mèng)想也許并不符合你的希望和夢(mèng)想。如果你的名字看上去已不再適合你,不要苦惱;你不必一輩子用這個(gè)名字。影星們就經(jīng)常改名,下點(diǎn)決心,你也可以這樣做。
第七單元
減輕負(fù)擔(dān),拯救生命
如果你常常生氣、身心疲乏,好像你生活中的壓力正在快速地積聚,將要失去控制,那么你可能是在損害你的心臟了。假如你不想損害自己的心臟,你就需要努力學(xué)會(huì)在力所能及的范圍內(nèi)控制自己的生活──并且承認(rèn)有許多東西你是無法控制的。
這是羅伯特·S.埃利奧特博士的觀點(diǎn)。他是內(nèi)布拉斯加大學(xué)的臨床醫(yī)學(xué)教授,新書《從壓力到力量:怎樣減輕你的負(fù)擔(dān),拯救你的生命》的作者。
埃利奧特說在這個(gè)世界上有一類他稱之為“熱核反應(yīng)堆式的人”(即易怒的人)。對(duì)這些人來說,緊張會(huì)導(dǎo)致他們血壓大幅度迅速上升。
埃利奧特說,研究人員已經(jīng)發(fā)現(xiàn),有壓力的人除了其他癥狀外,膽固醇的含量也較高?!拔覀円呀?jīng)做了多年研究,證明過分憂慮或緊張所產(chǎn)生的化學(xué)物質(zhì)的確會(huì)損傷心肌纖維。這種情況發(fā)生時(shí)往往很快,不到5分鐘。它會(huì)造成許多短路,而且這種短路會(huì)引起嚴(yán)重的心律不齊。
心臟跳起來不像一個(gè)泵,而像一只裝著蠕蟲的袋子(雜亂而又綿軟無力)。當(dāng)這種情況發(fā)生時(shí),我們就活不成了。”
現(xiàn)年64歲的埃利奧特,在44歲時(shí)曾有過一次心臟病發(fā)作,他把那次心臟病發(fā)作的部分原因歸于壓力。多年來,他一直是一個(gè)“熱核反應(yīng)堆式的人”。表面上,他顯得沉著、冷靜、泰然自若,但他內(nèi)心深處的壓力使他筋疲力盡。他現(xiàn)在身體狀況很好。他說,壓力破壞性程度的主要預(yù)測(cè)指標(biāo)是FUD因素──FUD指的是恐懼、猶豫和懷疑──再加上可察覺到的缺乏控制力。
對(duì)許多人來說,壓力的根源是憤怒,而對(duì)付憤怒的訣竅是找出怒從何來。埃利奧特問道:“這種憤怒是否來自這么一種感覺:希望一切事物都必須完美無缺?”
“這在職業(yè)女性中是很常見的原因。她們覺得要讓人人感到她們無所不能,而且要把樣樣事情都做得完美無缺。她們認(rèn)為,‘我應(yīng)該這樣,我必須這樣,我不得不這樣?!非笸昝烙罒o止境。完美主義者事必躬親。他們生氣是因?yàn)樗麄儾坏貌话咽裁词虑槎伎冈谧约杭缟?,還為之發(fā)脾氣。隨后他們就感到內(nèi)疚,接著他們就再把整個(gè)過程重復(fù)一遍?!?/p>
“還有的人生氣是因?yàn)樗麄兊纳顩]有方向。他們把交通阻塞看得和家庭糾紛一樣重,” 他說:“如果你生氣超過5分鐘──如果你生悶氣,沒有安全的發(fā)泄渠道的話──你就必須弄清你為何生氣。” “此時(shí)就會(huì)發(fā)生這種情況──人們由于心理壓力在生理上變得越發(fā)激動(dòng),他們的身體就越可能因?yàn)槟撤N心臟病而崩潰?!?/p>
讓自己平靜下來的做法就是承認(rèn)你存在這種傾向。通過改變你的某些看法和消極思想,學(xué)會(huì)對(duì)事物不再抱有那么強(qiáng)烈的敵視態(tài)度。
埃利奧特建議人們控制自己的生活。“如果有什么能取代壓力,那就是控制。
你所需要的不是FUD因素而是NICE因素──NICE是指新的、使人感興趣的、有挑戰(zhàn)性的歷。” “你必須確定你能控制自己生活中的哪些部分,”他說:“停下你的腳步,對(duì)自己說,‘我要把指南針拿出來,弄明白自己需要什么?!?/p>
他建議人們寫下他們覺得自己生活中最重要的、最想做成的6件事。本·富蘭克林在32歲時(shí)就是這樣做的?!八麑懴铝怂胍龅氖虑?,諸如要做一個(gè)更慈愛的父親、更體貼的丈夫、經(jīng)濟(jì)上獨(dú)立、思維上活躍,而且還要保持性情平和──這一點(diǎn)他也做得不好?!?/p>
埃利奧特說,你可以先列出12件事,然后壓縮到6件,要確定輕重緩急。“別讓自己去做不可能做到的事。要做那些會(huì)影響你的個(gè)性、控制能力和自我價(jià)值的事情?!?/p>
“把它們記在一張可以隨身攜帶的卡片上,需要的時(shí)候看看。既然我們無法讓一天有26個(gè)時(shí),我們就得確定先做哪些事情。”
請(qǐng)記?。弘S著時(shí)間的推移,優(yōu)先要做的事會(huì)有所改變?!昂⒆訒?huì)長大,狗會(huì)死去,你所優(yōu)先考慮做的事也會(huì)改變。”
根據(jù)埃利奧特的觀點(diǎn),控制壓力的另一關(guān)鍵因素是“要承認(rèn)你生活中還有一些棘手的、你幾乎無法或完全無法控制的東西──比如經(jīng)濟(jì)以及政客們。”
你必須認(rèn)識(shí)到,有時(shí)候像交通阻塞、最后期限及討厭的老板這類事情,“你無法抗?fàn)?,也無法逃避。你必須學(xué)會(huì)如何與之相容?!?/p>
第九單元
不要做生活的逃兵
“孩子,起來,做個(gè)有出息的人!”雖然母親已經(jīng)過世,但她的話依然清晰地在我腦海中回響,就如我在孩提時(shí)代聽到的一樣。
她心里也許是為我好,但那時(shí)依我看來,她那毫不溫柔的為母之道就如同用竹條鞭笞一般嚴(yán)厲?!疤炷?!”我叫道:“我已經(jīng)是個(gè)有出息的人了。我有權(quán)晚點(diǎn)起床了?!?/p>
“要是有什么我不能忍受的東西,那就是逃兵?!彼穆曇粼谖夷X海中回響,讓我無法拒絕,于是我從床上爬了起來。我的父親在婚后5年就過世了。他死后,我母親沒有錢。她要撫養(yǎng)三個(gè)孩子,還有一身的債務(wù)。當(dāng)時(shí)母親剛上大學(xué),卻不得不輟學(xué)去找工作。幾個(gè)月后,我們失去了房子,母親一無所有,只有支離破碎的生活殘局等著她去收拾。我那奄奄一息的精神失常的祖母不得不被送往瘋?cè)嗽海覀円仓荒芗木佑谒艿馨瑐惖募抑?。最終,母親找到了一份超市售貨員的工作,每周工資10美元。
雖然母親期望我能成為百萬富翁,但她很清楚我的能力,在這一點(diǎn)上,她從不欺騙自己。因此,從我很小的時(shí)候起,她就鼓勵(lì)我向文字工作的方向發(fā)展。
母親的家庭與文字素有淵源。最顯著的證據(jù)就是我母親最年長的堂兄埃德溫。他是《紐約時(shí)報(bào)》的執(zhí)行編輯,因報(bào)道古巴導(dǎo)彈危機(jī)而聲名大噪。她常用埃德溫的例子來告訴我一個(gè)有雄心的人能走多遠(yuǎn),即使他沒什么天賦?!鞍5聹亍ふ材肥侩m然打字速度比較快,但他并不比其他人聰明,你看,他現(xiàn)在多么功成名就,”我母親總是一遍又一遍地說。
她早就認(rèn)定我有文字天賦,從那時(shí)起,她就有了目標(biāo),她的整個(gè)生命便開始圍繞著幫助我開發(fā)天賦而運(yùn)轉(zhuǎn)。雖然很窮,她還是為我們訂了一套適合中高級(jí)水平讀者閱讀的讀物。每個(gè)月都會(huì)有一本書郵寄過來,價(jià)值39美分。
然而,我感興趣的卻是報(bào)紙。我貪婪地汲取每一條消息:駭人聽聞的罪行、可怕的事故、在遙遠(yuǎn)地區(qū)發(fā)生的戰(zhàn)爭(zhēng)對(duì)人們犯下的令人發(fā)指的罪行,以及不得不背井離鄉(xiāng)的難民的消息。警察貪污以及兇手死于電椅的報(bào)道令我著迷。
1947年,我從約翰斯·霍普金斯大學(xué)畢業(yè),向《巴爾的摩太陽報(bào)》應(yīng)聘警事記者一職。他們?yōu)楹芜x擇了我是個(gè)謎。工資是一周30美元。我抱怨薪水太低,這對(duì)一個(gè)有學(xué)問的人來說是侮辱,但母親卻不認(rèn)同?!叭绻闩ψ龊眠@份工作,”她說,“說不定能夠做出些名堂來?!?不久,我被委派去采訪非洲各國駐美大使館的外交官。工作七年后,《太陽報(bào)》派我去白宮采訪。對(duì)于一個(gè)記者來說,能夠從橢圓型辦公室發(fā)回報(bào)道已經(jīng)是達(dá)到職業(yè)的頂峰了。當(dāng)我把這個(gè)消息告訴母親時(shí),我期待著從她的臉上看到喜悅。但要是我能夠考慮到她為我設(shè)定的不斷向前邁進(jìn)、向上攀升的人生路線,我就不該有這種期待了?!昂茫?,” 她說:“要是你努力做好這份白宮的工作,你有可能會(huì)有所成就?!?/p>
母親并沒有對(duì)我取得的成就予以充分肯定。無論我做什么,我取得的成就在她看來都是微不足道的。這往往會(huì)讓我心煩。她從不向我道賀,從不承認(rèn)我做得很棒。即使在我成功的時(shí)候,她也是說一些否定的話?!凹词鼓愕竭_(dá)了巔峰,你還得留神。”她總是尖刻地指出,“成就越大,摔下來也越重?!?在我剛剛成為記者的幾年中,舅舅埃德溫的成就常??M繞在我腦中,揮之不去。我常想,要是《紐約時(shí)報(bào)》雇用我,該是件多么令人興奮的事情啊,那樣我就可以向母親一勞永逸地證明我的價(jià)值了。后來,連孩提時(shí)代也沒想過的是,《紐約時(shí)報(bào)》竟然自己來敲門了??上У氖牵?dāng)我去《紐約時(shí)報(bào)》工作時(shí)埃德溫舅舅已經(jīng)離開了那里。最后,我終于被委任了一個(gè)記者能夠夢(mèng)想得到最具榮譽(yù)性的工作:《紐約時(shí)報(bào)》的一個(gè)固定專欄的評(píng)論員。這證明了我母親在我小時(shí)候制定的、鼓勵(lì)我從事筆墨生涯的計(jì)劃是完全正確的。1979年,我達(dá)到了事業(yè)的頂峰,獲得了一個(gè)重大獎(jiǎng)項(xiàng)──普利策獎(jiǎng)。不幸的是,在這前一年,我母親的神志和健康狀況都完全崩潰了,她住進(jìn)了療養(yǎng)院,從此與世隔絕。她從來不知道我的普利策獎(jiǎng)。我大概可以猜到她會(huì)做出怎樣的反應(yīng)?!安诲e(cuò),孩子??磥?,要是你努力工作,總有一天你會(huì)成為一個(gè)出色的人?!?/p>