這是一個(gè)關(guān)于機(jī)械工程專業(yè)英語(yǔ)翻譯PPT課件，主要介紹機(jī)械工程的專業(yè)英語(yǔ)的相關(guān)內(nèi)容。機(jī)械工程 專業(yè)英語(yǔ)課程介紹學(xué)習(xí)專業(yè)英語(yǔ)的重要性學(xué)習(xí)目的為何在大三開(kāi)設(shè)這門課程專業(yè)英語(yǔ)的英文名稱“專業(yè)英語(yǔ)”----- English for Special Purpose Specified English for ……. “機(jī)械工程專業(yè)英語(yǔ)” Specified English for Mechanical Engineering 專業(yè)英語(yǔ)和普通英語(yǔ)的區(qū)別 一. 詞義特點(diǎn) 1. 根據(jù)詞類辨明詞義 e.g: (1) Round (adj.) surface reflector is a key unit for the solar energy device. 曲面反射器是太陽(yáng)能裝置的關(guān)鍵元件。 ( 2) This is the whole round (n.) of knowledge. 這是全部知識(shí)范圍。 2. 區(qū)分場(chǎng)合確定詞義（不同的場(chǎng)合，詞義也不一樣。要根據(jù) 上下文和語(yǔ)言環(huán)境來(lái)確定詞義） e.g: (1) pig: 豬 ~ iron 生鐵 (機(jī)械專業(yè)) ~ metal 金屬錠 ~ copper 生銅 (2) dog: 狗 (機(jī)械專業(yè)) ~ 雞心夾頭, 擋塊 3. 按照習(xí)慣搭配詞義 e.g: (1) I have a short memory. (2) This biscuit eats short. (3) Indeed he has a short temper. 4. 聯(lián)系上下文活用詞義 e.g: (1) There is no physical contact between tool and workpiece. 工具和工件之間沒(méi)有有形（直接）的接觸。 (2) High-speed grinding does not know this disadvantage 高速磨削不知道（存在）這個(gè)缺點(diǎn)，歡迎點(diǎn)擊下載機(jī)械工程專業(yè)英語(yǔ)翻譯PPT課件哦。

機(jī)械工程專業(yè)英語(yǔ)翻譯PPT課件是由紅軟PPT免費(fèi)下載網(wǎng)推薦的一款學(xué)校PPT類型的PowerPoint.

機(jī)械工程 專業(yè)英語(yǔ)課程介紹學(xué)習(xí)專業(yè)英語(yǔ)的重要性學(xué)習(xí)目的為何在大三開(kāi)設(shè)這門課程專業(yè)英語(yǔ)的英文名稱 “專業(yè)英語(yǔ)”----- English for Special Purpose Specified English for ……. “機(jī)械工程專業(yè)英語(yǔ)” Specified English for Mechanical Engineering 專業(yè)英語(yǔ)和普通英語(yǔ)的區(qū)別 一. 詞義特點(diǎn) 1. 根據(jù)詞類辨明詞義 e.g: (1) Round (adj.) surface reflector is a key unit for the solar energy device. 曲面反射器是太陽(yáng)能裝置的關(guān)鍵元件。 ( 2) This is the whole round (n.) of knowledge. 這是全部知識(shí)范圍。 2. 區(qū)分場(chǎng)合確定詞義（不同的場(chǎng)合，詞義也不一樣。要根據(jù) 上下文和語(yǔ)言環(huán)境來(lái)確定詞義） e.g: (1) pig: 豬 ~ iron 生鐵 (機(jī)械專業(yè)) ~ metal 金屬錠 ~ copper 生銅 (2) dog: 狗 (機(jī)械專業(yè)) ~ 雞心夾頭， 擋塊 3. 按照習(xí)慣搭配詞義 e.g: (1) I have a short memory. (2) This biscuit eats short. (3) Indeed he has a short temper. 4. 聯(lián)系上下文活用詞義 e.g: (1) There is no physical contact between tool and workpiece. 工具和工件之間沒(méi)有有形（直接）的接觸。 (2) High-speed grinding does not know this disadvantage 高速磨削不知道（存在）這個(gè)缺點(diǎn)。 二. 句子結(jié)構(gòu)特點(diǎn) 1. 句子長(zhǎng) 2. 被動(dòng)語(yǔ)態(tài)多 e.g: The rate at which work is done is called power. 3. 后置定語(yǔ)多 4. 名詞化結(jié)構(gòu)多 e.g: to control the machine ---- the control of the machine 學(xué)習(xí)方法與教學(xué)方法工具書的介紹 1. 收詞不足，收詞量有限 2. 收詞面廣 3. 例證豐富 4. 釋義地道， 全面 5. 詞的用法說(shuō)明較詳細(xì) Lesson 1 Introduction for Materials Designers and engineers are usually more interested in the behavior of materials under load or when in a magnetic field than in why they behave as they do. 1. are …. more interested in…. than in 對(duì)…..比對(duì)…..更興趣 2. under load ：承載時(shí) Yet the better one understands the nature of materials and the reasons for their physical and mechanical properties the more quickly and wisely will he/she be able to choose the proper material for a given design. 1. the better…. the more quickly and wisely : 越….越….. 2. a given design: 某個(gè)設(shè)計(jì) Generally， a material property is the measured magnitude of its response to a standard test performed according to a standard procedure in a given environment. 1. the measured magnitude: 測(cè)定的大小 2. response to: 對(duì)…..的反應(yīng) In engineering materials the properties are recorded in handbooks or， for new materials， are made available by the supplier. make sth. + 形容詞(sth. be make =形容詞): 使….怎么樣 the properties are made available : 使……可獲得 Frequently such information is tabulated for room-temperature conditions only， so when the actual service conditions are at subfreezing or elevated temperatures， more information is needed. 1. room-temperature conditions: 室溫狀態(tài) 2. the actual service conditions：實(shí)際工作狀態(tài) 3. elevated temperatures：高溫 The properties of materials are sometimes referred to as structure sensitive， as compared to structure-insensitive properties. 1. be referred to as， be known as : 稱為 2. (as) compared to (with): 與…相比， 同….比較起來(lái)， 與…相對(duì)應(yīng) 3. structure sensitive， structure-insensitive properties 結(jié)構(gòu)敏感性， 結(jié)構(gòu)不敏感性 In this case structure-insensitive properties include the traditional physical properties: electrical and thermal conductivity， specific heat， density， and magnetic and optical properties. electrical and thermal conductivity: 導(dǎo)熱性與導(dǎo)電性 specific heat: 比熱 specific weight: 比重 The structure-sensitive properties include the tensile and yield strength， hardness， and impact， creep， and fatigue resistance. 1. the tensile (strength) and yield strength: 拉伸強(qiáng)度和屈服強(qiáng)度 2. impact， creep， and fatigue resistance: 抗沖擊性，抗蠕性，抗疲勞性 It is recognized that some sources maintain that hardness is not a true mechanical property， because it varies somewhat with the characteristics of the indenter and therefore is a technological test. It is recognized that…. 認(rèn)出，識(shí)別， 考慮 (認(rèn)識(shí)) 到 some sources maintain: 一些資料(文件) It is well known that other mechanical properties vary significantly with rate of loading， temperature， geometry of notch in impact testing， and the size and geometry of the test specimen. 1. rate of loading: 載荷大小 2. geometry of notch in impact testing: 試驗(yàn)中缺口的幾何形狀 Furthermore， since reported test values of material properties are statistical averages， a commercial material frequently has a tolerance band of ±5 percent or more deviation from a given published value. 1. reported test values: 所報(bào)道的測(cè)量值 2. statistical averages: 統(tǒng)計(jì)平均值 3. commercial material: 商用材料 4. tolerance band: 公差帶 5. deviation from: 與….的偏差 6. a given published value: 某個(gè)公布的值 The properties of materials are sometimes referred to as structure sensitive， as compared to structure-insensitive properties. be referred to as: 指的是….; 叫做; be known as : 稱為; 叫做 In this case structure-insensitive properties include the traditional physical properties: electrical and thermal conductivity， specific heat， density， and magnetic and optical properties. 1. electrical and thermal conductivity: 導(dǎo)熱性與導(dǎo)電性 2. specific heat: 比熱 specific weight: 比重 The structure-sensitive properties include the tensile and yield strength， hardness， and impact， creep， and fatigue resistance. 1. tensile and yield strength tensile (strength) and yield strength 2. impact， creep， and fatigue resistance impact (resistance)， creep (resistance)， and fatigue resistance 抗沖擊性，抗蠕變性和抗疲勞性 It is recognized that some sources maintain that hardness is not a true mechanical property， because it varies somewhat with the characteristics of the indenter and therefore is a technological test. 1. It is recognized that ….. It is known that….. It is said that ….. 2. ….vary with…… Furthermore， since reported test values of material properties are statistical averages， a commercial material frequently has a tolerance band of ±5 percent or more deviation from a given published value. …..has a tolerance band of ±5 percent or more deviation from… … Any particular material can be described by its behavior when subjected to external conditions. …. described by behavior when (any particular material ) subjected to external condition ( 外力作用) Thus， when it is loaded under known conditions of direction， magnitude， rate， and environment， the resulting responses are called mechanical properties. When it is loaded under known conditions of direction， magnitude， rate， and environment …. Mechanical properties such as yield strength， impact strength， hardness， creep and fatigue resistance are strongly structure-sensitive， i.e.， they depend upon the arrangement of the atoms in the crystal lattice and on any imperfections in that arrangement， whereas the physical properties are less structure-sensitive. arrangement of the atoms: 原子排列 These include electrical， thermal， magnetic， and optical properties and do depend in part upon structure; for example， the resistivity of a metal increases with the amount of cold work. 1. in part: 部分 2. increases with: 隨著….而提高 3. cold work: 冷作; 冷成型，冷加工 Physical properties depend primarily upon the relative excess or deficiency of the electrons that establish structural bonds and upon their availability and mobility. 1. excess or deficiency: 超過(guò)或不足 2. structural bonds: 結(jié)構(gòu)鍵 Between the conductors with high electron mobility and the insulators with no free electrons， precise control of the atomic architecture has created semiconductors that can have a planned modification of their electron mobility. 1. high electron mobility: 高電子遷移率 2. the conductors with high electron mobility :高電子遷移率的導(dǎo)體 3. the insulators with no free electrons: 無(wú)自由電子的絕緣體 4. semiconductors that can have a planned modification of their electron mobility 有計(jì)劃改變電子遷移的半導(dǎo)體 Similarly， advances in solid-state optics have led to the development of the stimulated emission of electromagnetic energy in the microwave spectrum (masers) and in the visible spectrum (lasers). 1. solid-state optics: 固態(tài)光學(xué)器件 2. the stimulated emission: 激射 In studying the general structure of materials， one may consider three groupings; first， atomic structure， electronic configuration， bonding forces， and the arrangement of the aggregations of atoms; second， the physical aspect of materials， including properties such as electrical and thermal conductivity， specific heat， and magnetism; and third， their macroscopic properties， such as their mechanical behavior under load， which can be explained in terms of impurities and imperfections in the lattice structure and the procedures used to modify that behavior. 1. bonding forces: 結(jié)合力 2. aggregations of atoms: 原子團(tuán) 3. in terms of: 用….語(yǔ)言來(lái)…. 專業(yè)英語(yǔ)的特點(diǎn)專業(yè)英語(yǔ)（specified English）是在自然科學(xué)和工程技術(shù)的專業(yè)領(lǐng)域中使用的一種英語(yǔ)文體。它是在專業(yè)技術(shù)的不斷發(fā)展中逐漸形成并與專業(yè)技術(shù)同步發(fā)展的。由于專業(yè)技術(shù)的要求語(yǔ)言表述能客觀、嚴(yán)謹(jǐn)?shù)胤从晨茖W(xué)研究的內(nèi)容，所以，專業(yè)英語(yǔ)的特點(diǎn)，除了包含一些實(shí)驗(yàn)數(shù)據(jù)、公式推導(dǎo)和數(shù)學(xué)符號(hào)以外，在詞匯含義、語(yǔ)法結(jié)構(gòu)、句型使用和修辭手法等方面與日常英語(yǔ)、文學(xué)英語(yǔ)有不同的特點(diǎn)。這誠(chéng)如著名科學(xué)家錢三強(qiáng)指出的：專業(yè)英語(yǔ)“無(wú)論在語(yǔ)法結(jié)構(gòu)或詞匯方面都逐漸形成它特有的習(xí)慣用法、特點(diǎn)與規(guī)律”。不學(xué)習(xí)和掌握這些特點(diǎn)與規(guī)律，就很難搞好專業(yè)英語(yǔ)的閱讀、翻譯和寫作。為了掌握這些特點(diǎn)和規(guī)律，本章及下一章節(jié)將主要介紹專業(yè)英語(yǔ)的語(yǔ)法特點(diǎn)和詞匯特點(diǎn)。 一．專業(yè)英語(yǔ)的語(yǔ)法特點(diǎn) 1． 無(wú)人稱（Impersonal）（無(wú)生命的第三人稱語(yǔ)氣或非人稱語(yǔ)氣） 科技文體第一個(gè)顯著的特點(diǎn)就是較多地使用無(wú)生命的第三人稱語(yǔ)氣。 例如： Stepper motors are useful wherever accurate control of movement is required. They are used extensively in robotics and in printers， plotters and computer disk drives， all of which require precise positioning or speed. 凡需要精確控制運(yùn)動(dòng)的地方，步進(jìn)電機(jī)都非常有用。他們廣泛用于機(jī)器 人技術(shù)，打印機(jī)， 繪圖儀和計(jì)算機(jī)磁盤驅(qū)動(dòng)器，這些需要精確的定位或速度。 2．被動(dòng)語(yǔ)態(tài) ( Passive Voice ) 由于專業(yè)英語(yǔ)文獻(xiàn)側(cè)重?cái)⑹潞屯评�，陳述的�?duì)象是客觀事物。讀者重視的是作者的觀點(diǎn)和發(fā)明的內(nèi)容，而不是作者本人。因此在語(yǔ)言表述中必然較多地使用以客觀事物為主體的被動(dòng)語(yǔ)態(tài)。 專業(yè)英語(yǔ)中的被動(dòng)語(yǔ)句不一定要說(shuō)出行為主體，特別當(dāng)行為主體是人 時(shí)。但有時(shí)也用“by”引出行為者。這些行為者除了人、機(jī)構(gòu)、物質(zhì)以 外 ，還包括完成該動(dòng)作的方法、原因或過(guò)程等。例如： The temperature of the liquid is raised by the application of heat. 加熱可以提高液體溫度。 The rate at which work is done is called power. 3．非謂語(yǔ)動(dòng)詞 動(dòng)詞非謂語(yǔ)形式有：動(dòng)名詞、分詞、動(dòng)詞不定式及它們的復(fù)合結(jié)構(gòu)。 專業(yè)英語(yǔ)中，動(dòng)詞的非謂語(yǔ)形式應(yīng)用廣泛，這是因?yàn)閷�業(yè)英語(yǔ)要求準(zhǔn)確、精煉，而動(dòng)詞的非謂語(yǔ)形式可以很好地實(shí)現(xiàn)這些要求。比如采用這一形式能用擴(kuò)展的成分對(duì)所修飾的詞進(jìn)行嚴(yán)格的說(shuō)明和限定。其中每一個(gè)分詞定語(yǔ)都能代替一個(gè)從句，從而可使很長(zhǎng)的句子勻稱， 避免復(fù)雜的主從符合結(jié)構(gòu)，并省略動(dòng)詞時(shí)態(tài)的配合，使句子即不累贅又語(yǔ)意明確。 3. 1 分詞的使用 在專業(yè)英語(yǔ)中，分詞短語(yǔ)被大量地用作定語(yǔ)、狀語(yǔ)和獨(dú)立分詞結(jié)構(gòu)，取代被動(dòng)態(tài)或主動(dòng)態(tài)的關(guān)系從句，使句子結(jié)構(gòu)得到簡(jiǎn)化。例如： 1. Rammers driven by compressed air can increase the production rates. 壓縮空氣驅(qū)動(dòng)的舂砂器可以提高生產(chǎn)效率。 2. Originally designed for rapid， automatic production of screws and similar threaded parts， the automatic screw machine has long since exceeded the confines of this narrow field， and today plays a vital role in the mass production of a variety of precision parts. 自動(dòng)螺絲車床最初是用來(lái)對(duì)螺釘和類似的帶有螺紋的零件進(jìn)行自動(dòng) 化快速加工的。但是，這種車床的用途早就超過(guò)了這個(gè)狹窄的范圍�，F(xiàn) 在，它在許多種類的精密零件的大批量生產(chǎn)中起著重要的作用。 分詞獨(dú)立結(jié)構(gòu)，即： 名詞或代詞＋分詞短語(yǔ)，是一種主謂結(jié)構(gòu)，在句 中的作用相當(dāng)于并列分句或從句。例如： 3. Agitation is critical， the aim being to distribute silicon carbide particles homogeneously throughout the aluminum melt. 攪拌至關(guān)重要，其目的是將碳化硅顆粒均勻地分布在整個(gè)鋁液中。 分詞獨(dú)立結(jié)構(gòu)前加with (without) 變成起狀語(yǔ)作用的介詞短語(yǔ)，用于當(dāng) 分詞的邏輯主語(yǔ)與句子主語(yǔ)不一致時(shí)。 4. In the heat exchanger of blast furnace the air flows through the outside pipe， the gas through the inside pipe， with heat exchange taking place through the wall. 在高爐熱交換器中，空氣流過(guò)外管，燃?xì)饬鬟^(guò)內(nèi)管，熱交換通過(guò)管 壁進(jìn)行。 3. 2 動(dòng)名詞的使用 動(dòng)名詞構(gòu)成的介詞短語(yǔ)可取代狀語(yǔ)從句或簡(jiǎn)化陳述句，在英語(yǔ)中廣泛 應(yīng)用。例如： In redesigning an experimental part for production， economical tolerances should be used. 為了生產(chǎn)而重新設(shè)計(jì)試件時(shí)， 必須使用經(jīng)濟(jì)公差。 3. 3 不定式的使用 不定式在專業(yè)英語(yǔ)中的使用也十分頻繁，在句中常用來(lái)替換表示目的功能的從句，使句子結(jié)構(gòu)簡(jiǎn)練。例如： 1. To insure manufacture quality of electrodes， the American Welding Society has set up certain requirements for electrodes. 為了確保電極的制造質(zhì)量，美國(guó)焊接學(xué)會(huì)規(guī)定了電極必須具備的一些條件。 2. There is high requirement of skill in carrying out this operation to produce products with high performances. 進(jìn)行這項(xiàng)操作時(shí)需要很高的技巧，以生產(chǎn)出具有高性能的產(chǎn)品。 4. 名詞化結(jié)構(gòu) “表示動(dòng)作意義的名詞＋of＋名詞＋修飾語(yǔ)”叫做名詞化結(jié)構(gòu)。名詞化結(jié)構(gòu)具有文字明了、用詞簡(jiǎn)潔、結(jié)構(gòu)緊湊、表意客觀、信息容量大等特點(diǎn)，在專業(yè)英語(yǔ)中經(jīng)常用它代替主、謂結(jié)構(gòu)作各種句子成分，使句子結(jié)構(gòu)簡(jiǎn)化。例如: 用普通英語(yǔ)表達(dá)這樣一句話： The ultrasonic metal inspection is to apply ultrasonic vibrations to materials with elastic properties and to observe the resulting action of the vibrations in the materials. 用名詞化結(jié)構(gòu)如下表述： The ultrasonic metal inspection is the application of ultrasonic vibrations to materials with elastic properties and the observation of the resulting action of the vibrations in the materials. 金屬超聲波探傷是將超聲振動(dòng)施于具有彈性的材料，并觀察振動(dòng)在材料中產(chǎn)生的作用。 二．專業(yè)英語(yǔ)的詞匯特點(diǎn)專業(yè)英語(yǔ)詞匯的組成專業(yè)技術(shù)詞匯： polymerization 聚合作用 diathermometer 熱阻測(cè)定儀 mechatronics 機(jī)電一體化，機(jī)械電子學(xué) lathe 車床半專業(yè)技術(shù)詞匯： power 力量， 權(quán)力 （日常英語(yǔ)） 動(dòng)力 （機(jī)械專業(yè)） 電力 （電力專業(yè)） 冪 ( 數(shù)學(xué)專業(yè)） 功率 （物理專業(yè)） 爆發(fā)力 （體育專業(yè)） 構(gòu)詞法 英語(yǔ)的構(gòu)詞法包括轉(zhuǎn)化、合成、派生三種形式。轉(zhuǎn)化 (conversion) 如： melt 熔液——to melt熔化 finish光潔度——to finish精加工、拋光 alloy 合金——to alloy 使成合金復(fù)合法 (composition) 如： waveform 波形 ballbearing 滾珠軸承 workshop 車間 toolroom 工具室派生或詞綴 (derivation) 如： unavoidable 不可避免的 inaccuracy 不精確 詞匯縮略首字詞縮略: 它是由原詞組的每個(gè)詞首字母組成，在閱讀中首字詞要逐字母讀.例如： NC 數(shù)控 AC 自適應(yīng)控制 PLC 可編程控制器 AIEE American Institute of Electrical (Electronic) Engineers 美國(guó)電氣（電子）工程師學(xué)會(huì) 首字詞拼音: 把一個(gè)詞組中的首字母拼湊成一個(gè)詞.例如 laser — light amplification by stimulated emission of radiation 激光 ROM —— read only memory 只讀存儲(chǔ)器 AIDS —— acquired immune deficiency syndrome 愛(ài)滋病 節(jié)略詞: 某些詞使用頻率高，為了方便，在發(fā)展過(guò)程逐漸用 它們的前幾個(gè)字母來(lái)表示。例如： ref. —— reference 參考文獻(xiàn) lab. —— laboratory 實(shí)驗(yàn)室 in. —— inch 英吋 ft. —— foot 英呎 縮寫詞 例如： etc. — et cetera 等等 i.e — that is 即 e.g. — for example 例如 vs. — versus 對(duì)… 拼綴: 即以組成復(fù)合詞的各個(gè)詞中各抽取一或兩個(gè)詞綴相 拼合。例如： transeiver ( transistor ＋ receiver) 收發(fā)機(jī) mechatronics ( mechanics ＋ electronics) 機(jī)電一體化 distinguish 區(qū)別；區(qū)分 distort: 變形 by means of : 借助于 permanent: 永久的 coefficient: 系數(shù) steel mill: 鋼廠 expansion ：膨脹 roll: 軋錕 react to: 對(duì)….起作用; 對(duì)….的反應(yīng) crack: 裂開(kāi)，裂紋，破裂 in connection with: 與…..有關(guān) gradually: 逐漸地 five broad categories: 五大類 elasticity: 彈性 ductility: 延展性 toughness: 韌性 elevator: 升降機(jī) cable: 電纜 beam: 橫梁 penetration: 壓痕，凹痕 abrasion: 磨損 elongate: 延長(zhǎng)，伸長(zhǎng) Lesson 2 Metals and Ferrous Metals ferrous a. 鐵類的，黑色的 nonferrous a. 有色的 two general types 兩大類 broad main However， some nonferrous metals may contain a small amount of iron as an impurity. a small amount of: 少量的 a large amount of: 大量的 varying amounts: 不同數(shù)量的 Steel and cast iron are the most common ferrous metals in general use. cast iron 鑄鐵 general use 普通的用途 Steel is an alloy containing chiefly iron，…… and certain other elements in varying amounts. A wide range of physical properties may be obtained in steel by controlling the amount of carbon and other alloying elements and by subjecting the steel to various heat treatment. a wide range of: 各種各樣的，形形色色的 be subjected to : 易受到，承受 subject sth. to……: 使….承受….. Alloy steels are formed by the addition of one or more of the following elements. by far: 迄今 It is the amount of carbon present which largely determines the maximum hardness obtainable. It is + 強(qiáng)調(diào)部分 + which…….. The higher the carbon content， the higher the tensile strength and the greater the hardness to which the steel may be heat-treated. → The steel may be heat-treated to the hardness. …….parts requiring a great deal of forming. a great deal of……: 大量 Medium-carbon steels are used for forgings and other applications where increased strength and a certain amount of ductility are necessary. Alloy steels have special properties determined by the mixture and the amount of metals added. mixture: 混合物→金屬種類 To the metallurgist who works in metal mining and manufacturing， steels containing very small quantities of elements other than carbon， phosphorus， sulphur， and silicon are known as alloy steels. work in： 從事 other than：除了…….. be known as……: 叫做，稱為 be known for….: 因….而著名 be known to……: 被知道 Each alloy steel has a personality of its own. Tool-and-die steels are a large group of steels used when careful heat-treating must be done. These steels are used for parts such as chisels， hammers， screwdrivers， springs， and tools and dies used to cut and form metals. Tool steels with certain alloying elements are designed for specific uses. be designed to ….. 設(shè)計(jì)成能(做)， 用來(lái)…， 目的是使… be designed for….. 用做…用途; 為….而設(shè)計(jì) specific: a. 1.比率，單位的 e. g: specific heat， specific weight 2. 特殊(定，有，種)的; 專門的; 具體的，明確的 The most common kinds of tool steels include high-speed tool steels， hot work tool steels， cold work tool steels and special-purpose tool steels. hot work tool steels 熱加工工具鋼 cold work tool steels 冷加工工具鋼 special-purpose 專用的 special-purpose machines general-purpose 通用的 general-purpose machines Rolled steel， which includes bar， rod， and structural steels， is produced by rolling the steel into shape. bar 扁鋼 rod 圓鋼 by rolling the steel into shape 軋制成形的方法…. Hot-rolled steels are formed into shape while the metal is red-hot. are formed into shape 成形 The metal passes through a series of rollers， each a little closer to the next one. roller: 軋錕 each， one ---- a series of rollers As the steel passes through the last rollers， hot water is sprayed over it， forming a bluish scale. a bluish scale 淡藍(lán)色的氧化層 This steel is fairly uniform in quality and is used for many different kinds of parts. uniform a. 均勻 Hot-rolled bars of the best quality are used to produce cold-finished steels. cold-finished steels 冷精軋鋼 Cold- finished steels are used when great accuracy， better surface finish， and certain mechanical properties are needed. surface finish 表面光潔度 The most common results in what is called cold-worked steel. the most common (way): 最常見(jiàn)的方法 results in: 導(dǎo)致，引起，產(chǎn)生 what is called cold-worked steel: 所謂的冷作鋼 After the scale from the hot-rolled bars is removed， one of two techniques is employed. (1) The bars are cold-drawn， that is， drawn through dies a few thousandths smaller than the original bar. cold-drawn： 冷拔 die： 拉模 (2) The steel is cold-rolled， that is， rolled cold to the exact size. cold-rolled: 冷軋 Drill rod is a grade of high-carbon tool steel or high-speed steel. drill rod：鉆桿 a grade of：一種 It is finished by grinding and polishing so that the outside is smooth and very accurate in size. it:指 drill rod finish: v. 精加工 n. 光潔度 You can identify drill rod by its shiny surface， which is much smoother than any of the other steels used in the shop. identify……by…. 通過(guò)(用)……來(lái)識(shí)別 shop: 車間 Drill-rod bars are generally made in 3-ft lengths and come in round， hexagonal， and square shapes. Cast iron is used for the heavy parts of many machines. Cast iron is low in cost and wears well. It is very brittle， however， and cannot be hammered or formed. hammered or formed. 鍛壓成形 The basic kinds of cast iron are white iron， gray iron， and malleable iron. Malleable iron is a particular kind of cast iron， made more malleable by an annealing procedure. an annealing procedure 退火工序 Malleable-iron castings are not so brittle or hard. They can stand a great deal hammering. Many plumbing fixtures are made of malleable iron. plumbing fixtures: 管接頭 Nodular iron is a kind of cast iron that is even better for withstanding shocks， blows， and jerks. nodular iron 球墨鑄鐵 Lesson 3 Gears spur (gears) and helical gears 直齒輪與斜齒輪 A gear having tooth elements that are straight and parallel to its axis is known as a spur gear. A spur pair can be used to connect parallel shafts only. Parallel shaft， however， can also be connected by gears of another type， and a spur gear can be mated with a gear of a different type (Fig. 3-1). mate， mesh : 嚙合 To prevent jamming as a result of thermal expansion， to aid lubrication， and to compensate for unavoidable inaccuracies in manufacture， all power-transmitting gears must have backlash. power-transmitting gears：動(dòng)力傳動(dòng)齒輪 This means that on the pitch circles of a mating pair， the space width on the pinion must be slightly greater than the tooth thickness on the gear， and vice versa. a mating pair ：一對(duì)嚙合齒輪 vice versa：反之亦然 On instrument gears， backlash can be eliminated by using a gear split down its middle， one half being ratable relative to the other. eliminate：消除 split：裂開(kāi) relative to：相對(duì)于 A spring forces the split gear teeth to occupy the full width of the pinion space. Helical gears have certain advantages; for example， when connecting parallel shafts they have a higher loadcarrying capacity than spur gears with the same tooth numbers and cut with the same cutter. with the same tooth numbers spur gears cut with the same cutter. Because of the overlapping action of the teeth， they are smoother in action and can operate at higher pitch-line velocities than spur gears. the overlapping action: 交錯(cuò)重疊作用 at …… velocities : 以….的速度 Since the teeth are inclined to the axis of rotation， helical gears create an axial thrust. be inclined to: 向…..傾斜 If used singly， this thrust must be absorbed in the shaft bearings. If used singly : if the single helical gear is used， absorb : 吸收 承受 The thrust problem can be overcome by cutting two sets of opposed helical teeth on the same blank. two sets of opposed helical teeth on the same blank. 在同一個(gè)坯件上切削兩組相反的斜齒 Depending on the method of manufacture， the gear may be of the continuous-tooth herringbone variety or a double-helical gear with a space between the two halves to permit the cutting tool to run out. continuous-tooth herringbone variety: 連續(xù)人字形 a double-helical gear: 雙斜齒輪 Double-helical gears are well suited for the efficient transmission of power at high speeds. Helical gears can also be used to connect nonparallel， non-intersecting shafts at any angle to one another. Ninety degrees is the commonest angle at which such gears are used. 最常用的角度為90· worm and worm gears 蝸桿蝸輪 In order to achieve line contact and improve the loadcarrying capacity of the crossed-axis helical gears， the gear can be made to curve partially around the pinion， in somewhat the same way that a nut envelops a screw. 為了使交叉軸斜齒輪獲得線接觸和提高承載能力，可以把大齒輪作成部分繞小齒輪彎曲，就象螺母套在螺桿上一樣. The result would be a cylindrical worm and gear. 結(jié)果就形成一個(gè)柱形蝸桿和蝸輪 Worm gears provide the simplest means of obtaining large ratios in a single pair. means: 方法，手段 large ratios in a single pair 一對(duì)大速比齒輪 They are usually less efficient than parallel-shaft gears， however， because of an additional sliding movement along the teeth. an additional sliding movement 附加滑動(dòng) Because of their similarity， the efficiency of a worm and gear depends on the same factors as the efficiency of a screw. Single-threads worms of large diameter have small lead angles and low efficiencies. single-threads worm 單頭蝸桿 multiple-thread worm 多頭蝸桿 lead angle 導(dǎo)角 For transmitting rotary motion and torque around corners， bevel gears are commonly used. ….transmitting rotary motion and torque around corners … 傳遞旋轉(zhuǎn)運(yùn)動(dòng)以及繞著一個(gè)角度傳遞扭距…. The connected shafts， whose axes would intersect if extended， are usually but not necessarily at right angles to one another. axis (單數(shù)) ， axes (復(fù)數(shù)) not necessarily 不一定 to one another， to the other 相互 When adapted for shafts that do not intersect， spiral bevel gears are called hypoid gears. When (spiral bevel gears) adapted for shafts….. The pitch surfaces of these gears are not rolling cones， and the ratio of their mean diameters is not equal to the speed ratio. Consequently， the pinion may have few teeth and be made as large as necessary to carry the load. The profiles of the teeth on bevel gears are not involutes; they are of such a shape that the tools for cutting the teeth are easier to make and maintain than involute cutting tools. Since bevel gears come in pairs， as long as they are conjugate to one another they need not be conjugate to other gears with different tooth numbers. Comment on Exercise one One material can often be distinguished from another by means of physical properties， such as color， density， specific heat， coefficient of thermal expansion， thermal and electrical conductivity， magnetic properties， and melting point. 一種材料與另一種材料的區(qū)別經(jīng)�？梢酝ㄟ^(guò)其物理性能，如……. 一種材料經(jīng)�？梢酝ㄟ^(guò)其物理性能與另一種材料區(qū)別開(kāi)來(lái)， 如….. 熱膨脹系數(shù)，導(dǎo)熱性和導(dǎo)電性 Some of these， for example thermal conductivity， electrical conductivity， and density， may be of prime importance in selecting material for certain specific uses. 其中一些性能，如:……… In + v.-ing : 在…..時(shí)候 ………….在為某些特定用途選擇材料的時(shí)候…….. Those properties that describe how a material react to mechanical usage are often more important to the engineer in selecting materials in connection with design. 描述材料如何對(duì)機(jī)械使用起反應(yīng)的 那些性能對(duì)…..更重要. 在選擇與設(shè)計(jì)有關(guān)的材料時(shí)，…. These mechanical properties relate to how the material will react to the various loading during service. 材料在使用中(如何)對(duì)各種載荷的反應(yīng) relate to: 與….有關(guān) Mechanical properties are the characteristic responses of a material to applied forces. responses of A to B ----- A respond to B A對(duì)B的反應(yīng) applied forces 外力 the characteristic responses 特性的反應(yīng) These properties fall into five broad categories: strength， hardness， elasticity， ductility， and toughness. fall into : 變 (分) 成; 分解 five broad ( main， major )categories : 五大類 1. Strength is the ability of a material which resists applied forces. Elevator cables and buildingss beams all must have this property. applied forces: 施加的力 外力 2. Hardness is the ability of a material which resists penetration and abrasion. Cutting tools must resist abrasion， or wear. Metal rolls for steel mills must resist penetration. abrasion， or wear：磨損 mate or mesh : 嚙合 3. Elasticity is the ability of a metal to return to its original shape after being elongated or distorted， when the forces are released. All springs should have this quality. 4. Ductility is the ability to undergo permanent changes of shape without breaking. A metal having high ductility， (such as copper or soft iron， ) will fail or break gradually as the load on it is increased. A metal of low ductility，( such as cast iron， ) fail suddenly by cracking when subjected to a heavy load. 5. Toughness is the ability to absorb mechanically applied energy. Strength and ductility determine a material’s toughness. Toughness is needed in railroad cars， automobile axles， hammers， and similar products. 第二章 專業(yè)英語(yǔ)翻譯理論 2. 1 翻譯的定義 語(yǔ)言是人類交流思想的一種手段，使用不同語(yǔ)言的人們要交流思想， 必須借助翻譯。 所謂“翻譯”就是一種語(yǔ)言文字的思想內(nèi)容和風(fēng)格用另一種語(yǔ)言的習(xí)慣表達(dá)方式確切而完整地重新表達(dá)出來(lái)的過(guò)程。 2. 2 翻譯的本質(zhì) 語(yǔ)言實(shí)際上就是一種語(yǔ)碼，英語(yǔ)名叫code。Code 這個(gè)詞既可以是明碼，也可以是密碼。人們用語(yǔ)言進(jìn)行交流的過(guò)程，就是“用（Encode）和“解碼”(Decode) 的過(guò)程。所謂“用碼”就是人們把自己想描述的客觀事實(shí)，想要的表達(dá)的思想情感，轉(zhuǎn)換成語(yǔ)碼，即用語(yǔ)碼來(lái)表達(dá)。所謂“解碼”，就是用語(yǔ)言表達(dá)出來(lái)的信息，理解后還原成所表達(dá)的客觀事物或思想情感。所以，翻譯的本質(zhì)就是一個(gè)對(duì)原語(yǔ)的密碼進(jìn)行破譯，也即“解碼”，對(duì)譯語(yǔ)用明碼進(jìn)行表達(dá)，即“用碼”的語(yǔ)言活動(dòng)。 2. 3 翻譯的標(biāo)準(zhǔn) 翻譯的標(biāo)準(zhǔn)既是衡量譯文質(zhì)量的尺度，也是指導(dǎo)翻譯實(shí)踐的準(zhǔn)則，因此翻譯的標(biāo)準(zhǔn)一直是翻譯工作者關(guān)注的問(wèn)題，其中最有影響的是清末著名的翻譯家嚴(yán)復(fù)先生在1898年提出的“信、達(dá)、雅三原則。由于這個(gè)提法嚴(yán)謹(jǐn)準(zhǔn)確，歷來(lái)為后人所推崇，至今仍有很大影響。只是隨著時(shí)代的發(fā)展，人們對(duì)翻譯標(biāo)準(zhǔn)的認(rèn)識(shí)，已有了一些進(jìn)一步的見(jiàn)解。就科技英語(yǔ)的翻譯而言，人們更趨向于劉重德教授提出的“信、達(dá)、切”標(biāo)準(zhǔn)。 2. 4 翻譯的基本方式及其選擇 2.4.1翻譯的基本方式 翻譯的基本方式有直譯，意譯，音譯，闡譯四種． 1. 直譯 所謂直譯，就是既忠實(shí)于原文的內(nèi)容，又忠實(shí)于原文的形式的翻譯方式．英漢兩種語(yǔ)言，其句子的主干成份的語(yǔ)序在基本句型中是一致的．這便為直譯這種翻譯的基本方式奠定了基礎(chǔ)．如英語(yǔ)中的：Two plus two equals four.　 譯成漢語(yǔ)便是： 二加二等于四． 可以看出，在上述句型中，兩種語(yǔ)言的語(yǔ)序是完全一致的．因此，可以用直譯的方式． 直譯是最為重要的方式，也是所有翻譯方式的基礎(chǔ)。但應(yīng)該指出的是，直譯并不等于死譯，不能望文生義。 如前所述，直譯能保證或基本保證與原文在形式上的一致，從而具有更忠實(shí)于原文的效果。所以翻譯時(shí)首選直譯。 意譯 所謂意譯，就是只忠實(shí)于原文的內(nèi)容，不拘泥于原文的形式的一種翻譯方式。也就是說(shuō)，當(dāng)譯文與原文在神似與形似不能統(tǒng)一時(shí)，只得重神似而不重形似了，這便是意譯。試以下述兩句為例。 a. Though a translation may be like oil wine in new bottles or a woman in man’s clothing， the results can be both tasteful and alive. 盡管一篇譯文猶如新瓶裝舊酒或是女扮男裝，但它們的效果仍舊可 以甘醇香甜和楚楚動(dòng)人 b. A translation may preserve old content in new form with all its taste and liveliness. 一篇譯文可以以新形式傳達(dá)原文的內(nèi)容，并保持原文的色彩和風(fēng)姿。 上述兩句深層語(yǔ)義相通但表層結(jié)構(gòu)的簡(jiǎn)繁，選詞的色彩卻相去甚遠(yuǎn)。如果把 b句的譯文作為 a 句的譯文，這在翻譯上就稱之為意譯。 應(yīng)當(dāng)指出：采用意譯方式時(shí)，應(yīng)注意的是一定要以神似為原則，不能意譯過(guò)頭。意譯不等于自由翻譯。意譯過(guò)頭，就是翻譯上的自由主義。 Lesson 4 Shafting and Couplings Shafting is the machine member that supports a roller and wheel so that they can perform their basic functions of rotation. Shafting：傳動(dòng)軸 the machine member， the mechanical element: 機(jī)械構(gòu)件，機(jī)械零件 support: 支持， 支撐 basic functions of rotation: 基本的旋轉(zhuǎn)功能 傳動(dòng)軸是支撐滾輪和輪子機(jī)械零件以便它們能夠完成基本的轉(zhuǎn)動(dòng)功能 傳動(dòng)軸是支撐滾輪和輪子使它們能夠完成基本轉(zhuǎn)動(dòng)功能的機(jī)械零件。 Shafting， made from round metal bars of various lengths and machined to dimension the surface， is used in a great variety of shapes and applications. a great variety of 各種各樣的 round metal bars 金屬棒 machine n. 機(jī)床 v. 加工 dimension n. 尺寸 v. 標(biāo)尺寸，定尺寸 Because shafts carry loads and transmit power， they are subject to the stresses and strains of operating machine parts. be subject to : 承受 the stresses and strains：應(yīng)力與應(yīng)變 machine parts：機(jī)器零件 Standardized procedures have been evolved for determining the material characteristics and size requirements for safe and economical construction and operation. standardized procedures 標(biāo)準(zhǔn)化的步驟 evolve: 改進(jìn) safe and economical construction and operation 結(jié)構(gòu)和操作的安全性 和經(jīng)濟(jì)性 Most shafting is rigid and carries bending loads without appreciable deflection. rigid：adj. 剛性的 rigidity n. bending loads 彎曲載荷 deflection 撓度 Some shafting is highly flexible. It is used to transmit motion around corners. flexible：柔性 motion around corners 繞著角度運(yùn)動(dòng) solid shafting 實(shí)心軸 The normal form of shafting is a solid bar. Solid shafting is obtainable commercially in round bar stock up to 15 cm in diameter; it is produced by hot-rolling and cold-drawing or by machine-finishing with diameters in increments of 6mm or less. For larger sizes， special rolling procedures are required， and for extremely large shafts， billets are forged to the proper shape. special rolling procedures : 專門的軋制工序 extremely large shafts：特大軸 Particularly in solid shafting， the shaft is stepped to allow greater strength in the middle portion with minimum diameter on the ends at the bearings. The steps allow shoulders for positioning the various parts pressed onto the shaft during the rotor assembly. shoulder：軸肩 position ：位置 定位 the rotor assembly ：轉(zhuǎn)子裝配 hollow shafting， solid shafting To minimize weights， solid shafting is bored out or drilled， or hollow pipes and tubing are used. bore: 鏜孔 drill: 鉆孔 pipe：空心管 tubing：管材 Hollow shafts also allow internal support or permit other shafting to operate through the interior. internal support : 內(nèi)部支撐 interior ：內(nèi)部（側(cè)），里面 The main shaft between the air compressor and the gas turbine in a jet aircraft engine is hollow to permit an internal speed reduction shaft with the minimum requirement of space and weight. air compressor ：空氣壓縮機(jī) gas turbine：燃?xì)馕佪?jet aircraft engine：噴氣式飛機(jī)發(fā)動(dòng)機(jī) internal speed reduction shaft：內(nèi)部減速軸 A hollow shaft， to have the same strength in bending and torsion， has a larger diameter than a solid shaft， but its weight is less. to have the same strength in bending and torsion 不定式短語(yǔ)表示目的 The center of large shafts made from ingots are often bored out to remove imperfections and also to allow visual inspection for forging cracks. visual inspection：目測(cè) forging cracks：鍛造裂縫 Another important aspect of shaft design is the method of directly connecting one shaft to another. This is accomplished by devices such as rigid and flexible couplings. rigid coupling 剛性聯(lián)軸器 flexible couplings 柔性聯(lián)軸器 A coupling is a device for connecting the ends of adjacent shafts. adjacent shafts：相鄰的軸 In machine construction， couplings are used to effect a semipermanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machine， but it can be broken and restored in an emergency or when worn parts are replaced. sense：意義 worn parts：磨損件 a flanged rigid coupling：法蘭盤剛性聯(lián)軸器 Torque is transmitted directly through this type of connector ; therefore， the two shafts must have straight， collinear centerlines. This type allows for no linear or angular misalignment. linear or angular misalignment：直線或角度偏差 A flange is keyed to each of the connection shafts; then a series of through bolts is used to connect the flanges. key：n.鍵 vt. 用鍵連接（定位） through bolts 貫穿螺栓，穿釘 The bolt holes are usually counterbored to prevent the fasteners from projecting beyond the face of the flange; this reduces a potential safely hazard. fastener：緊固件 a potential safely hazard：隱患 To calculate the size of through bolt required， the size of the bolt circle must be known， as well as the number of bolts， the allowable stress， and the torque to be transmitted. the bolt circle：螺栓分布圓 allowable stress：許用應(yīng)力 the sleeve coupling 套筒聯(lián)軸器 This is merely a sleeve that connects the two shafts; the shafts must be correctly aligned， since there is no flexibility to the coupling. The sleeve is then fastened with setscrews to the two shafts. The amount of torque that can safely be handle depends on the holding power of the setscrews. ….. that can safely be handle（定語(yǔ)從句)精確地控制(確定) holding power: 夾持力 Sometimes a drive pin (pin with grooved slots) is used; in that case， a hole is drilled through the sleeve and shaft. Because of manufacturing tolerances in the fabrication and mounting of parts， perfect shaft alignment is almost impossible to achieve. the fabrication and mounting of parts: 零件的制造與安裝 When two shafts are connected with rigid couplings， any misalignment (linear or angular) has detrimental effects on several parts of the assembly. Some of these effects are (1) reversed flexure on shafts， (2) unexpected and excessive loads on bearings， and (3) excessive vibration. reversed flexure on shafts 軸的逆向扭曲 Flexible couplings can eliminate some of these problems， provided the amount of misalignment is not too great. provided (that) + 從句; providing (that) + 從句 Fig.4-3 shows a type of coupling suitable for linear misalignment， although a certain amount of angular error can also be handled. an Oldham-type coupling: 十字聯(lián)軸器 The end sections are rigidly attached to the shafts. Be attached to: 與…..相連 Both end sections contain a rectangular slot that faces the center section; the “floating” central section is provided with a rectangular projection on each side that engages the slots in the end pieces. the “floating” central section: 中間的鏈接部分 engage: 配合; 嚙合 The two rectangular projections are at right angles to each other. This “floating” section will slide in the grooves of the end pieces as the shaft rotates. The middle section is usually made of a material unlike that of the end sections; nylon or one of the sintered powdered metals (containing a lubricant) is often used. the sintered powdered metals: 燒結(jié)粉末金屬 Use of a suitable material for the “floating” section can do much to reduce the amount of friction caused by the sliding action. Commons on Exercises 1. Translate the following words into Chinese: 1) sizes of spur-gear teeth 2) the tangency point 3) the radial distant 4) a line perpendicular to the centerlines 5) rack-and-pinion drives 6) an involute curve 7) the average number of teeth in contact 8) center distance between two meshed gears 2. Translate the following sentences into Chinese: Pressure angles for spur gears are usually 14.5 or 20 degrees， although other values can be used. Meshing gears must have the same pressure angles. Worm gears are used where high ratios are desired and where the shafts are nonintersecting and at right angles. Bevel gears are often used when two shafts are at right angles to each other and their centerline extensions intersect; however， some bevel gears are at angles other than 90 degrees. The shape of the space between gear teeth is complex and varies with the number of teeth on the gear as well as tooth module， so most gear manufacturing methods generate the tooth flank instead of forming. 增譯法 1. 英語(yǔ)復(fù)數(shù)名詞的增譯： 復(fù)數(shù)名詞前可增加適當(dāng)?shù)谋硎緩?fù)數(shù)概念的詞，如“一些”、“許多”、“一批”、“各種”等詞，使其復(fù)數(shù)意義更加明確。例如：（1）After a series of experiments important phenomena have been ascertained. 經(jīng)一系列實(shí)驗(yàn)后，查明了_______ 重要現(xiàn)象。 2. 英語(yǔ)中表示動(dòng)作意義名詞的增譯： 在翻譯英語(yǔ)文獻(xiàn)時(shí)，常須根據(jù)上下文的意義來(lái)補(bǔ)充一些表示動(dòng)作意義的名詞，如“作用”、“現(xiàn)象”、“效應(yīng)”、“方法”、“過(guò)程”等等。例如： Oxidation will make iron and steel rusty. 氧化_______ 會(huì)使鋼鐵生銹。 3 添加概括性的詞引起的增譯： 在句中列舉幾種情況時(shí)，可根據(jù)并列成分?jǐn)?shù)量的多少，增譯數(shù)、量詞表示概括。例如： The factors， voltage， current and resistance， are related to each other. 電壓、電流和電阻這_______ 因素是相互關(guān)聯(lián)的。 4. 添加語(yǔ)氣連貫性詞引起的增譯： 為了使譯文的上下文措詞連貫，也就是使譯文表達(dá)通順，使詞與詞、句與句之間前后連貫，有時(shí)要增譯語(yǔ)氣連貫性的詞，使前后語(yǔ)氣加強(qiáng)聯(lián)系，主要是連詞、介詞和副詞。 例如： Many persons learned to program with little understanding of computers and their applications. ________許多人對(duì)計(jì)算機(jī)及其應(yīng)用沒(méi)有多少了解______卻學(xué)會(huì)了編程序。 5. 被動(dòng)語(yǔ)態(tài)引起的增譯 英漢翻譯中，有時(shí)會(huì)將被動(dòng)語(yǔ)態(tài)譯成主動(dòng)語(yǔ)態(tài)。這時(shí)原文中沒(méi)有出現(xiàn)的行為主體便會(huì)在譯文中出現(xiàn)，因而也就引起增譯。例如： Rubber is found a good material for the insulation of cable. ________發(fā)現(xiàn)橡膠是一種用于電纜絕緣的理想材料。 The mechanical energy can be changed back into electrical energy by means of a generator. 利用發(fā)電， _______ 機(jī)械能轉(zhuǎn)換成電能. Lesson 5 Bearings A bearing can be defined as a member specifically designed to support moving machine components. moving machine components 運(yùn)動(dòng)著的機(jī)器零件 The most common bearing application is the support of a rotating shaft which is transmitting power from one location to another; one example is the crankshaft bearings of the automotive engine; another example is the shaft bearing used in all types of electric motors. the crankshaft bearings 曲軸軸承 the automotive engine 汽車引擎 electric motors 電機(jī) Since there is always relative motion between a bearing and its mating surface， friction is involved. relative motion 相對(duì)運(yùn)動(dòng) friction is involved 涉及到摩檫 In many instances， such as the design of pulleys， brakes and clutches， friction is desirable. pulleys， brakes and clutches 滑輪， 剎車和離合器 However， in the case of bearings， the reduction of friction is one of the prime considerations. in the case of 就…….而言 Friction results in loss of power， the generation of heat and increased wear of mating surfaces. results in 導(dǎo)致， 引起 result from 由于 Journal and antifriction bearings are the two general types of bearings in existence. Journal and antifriction bearings 軸頸軸承和減摩軸承 in existence 現(xiàn)有的， 存在的， 現(xiàn)存的 Journal bearings operate with sliding contact， whereas antifriction bearings experience predominantly rolling contact. whereas， while : 然而 The amount of sliding friction in journal bearings depends on the surface finishes， materials， sliding velocities and the type of lubricant used. The principal motion-retarding effect in antifriction bearings is called rolling resistance rather than rolling friction. motion-retarding effect 運(yùn)動(dòng)阻滯效應(yīng) rolling resistance 滾動(dòng)阻力 rolling friction 滾動(dòng)摩檫 This is so because the resistance of motion is essentially due to the deformation of the rolling elements and， hence， it is not a sliding phenomenon. To reduce the problems associated with sliding friction in journal bearings， a lubricant is used in conjunction with compatible mating materials. in conjunction with 和…..一起(共同，會(huì)合)， 連同…..一起 compatible mating materials 相容的配合材料 When selecting the lubricant and mating materials， one must take into account bearing pressures， temperatures and also rubbing velocities. take into account 把….考慮進(jìn)去 bearing pressures 承受的壓力 The principal function of the lubricant in sliding contact bearings is to prevent physical contact between the rubbing surfaces. rubbing surfaces 磨檫面 Thus the maintenance of an oil film under varying loads， speeds and temperatures is the prime consideration in sliding contact bearings. oil film 油膜 Journal bearing， in its simple form， is a cylindrical bushing made of a suitable material and containing properly machined inside and outside diameters. made of a suitable material a cylindrical bushing 圓柱形軸瓦 containing properly machined inside and outside diameters 包含適當(dāng)加工的內(nèi)徑和外徑 The journal is usually the part of a shaft or pin that rotates inside the bearing. journal：軸徑 the part of a shaft or pin：那部分軸或銷 Fig 5-1 shows such a bearing， which is also commonly called a sleeve bearing. a sleeve bearing：套筒軸承 Notice the oil hole that leads to an axial oil groove. lead to: 通向 an axial oil groove：軸向油槽 Such a bearing is designed to provide lubrication to reduce friction. The bore (inside diameter) of a journal bearing is machined to accept a rotating shaft， as shown in Fig. 5-2 (a). bore：v. 鏜孔 n. 內(nèi)徑 The bearing outside diameter is supported in a properly machined bore of a fixed housing. a properly machined bore of a fixed housing: 適當(dāng)加工的內(nèi)孔 固定的殼體 An oil cup is shown attached to one side of the housing， where a passageway leads to the oil hole of the bushing. one side of the housing: 殼體的一側(cè) passageway: 通路 Notice that the axial oil groove in the bushing does not extend all the way to the ends of the bearing. extend all the way to: 延伸到 This prevents undue loss of oil from the bearing. undue loss Moreover， notice the annular groove in the bushing in Fig. 5-2 (a); such grooves ensure more complete distribution of the lubricant. Since there will normally be a load R coming into the bearing， a normal force N and friction force F will exist between the shaft and bushing， as shown in Fig. 5-2 (b). Even though bearings are usually lubricated， there is friction and some wear. With time， the friction will result in wearing down of the bushing bore. wearing down of the bushing bore 軸瓦內(nèi)徑向下磨損 Proper selection of bearing materials is an important design consideration. Ball and roller bearings can be designed to absorb thrust loads in addition to radial loads， whereas needle bearings are limited to radial load applications only. thrust loads 軸向載荷 radial loads 徑向載荷 be limited to 局限于 Antifriction bearings operate with rolling elements (either balls or rollers) and， hence， rolling resistance， rather than sliding friction， predominates. operate with rolling elements: 利用滾動(dòng)體來(lái)工作 The cause of rolling resistance is the deformation of the mating surfaces of the rolling elements and raceways. The three basic types of antifriction bearing are (a) ball bearings; (b) roller bearings; (c) needle bearings. One of the principal advantages of antifriction (rolling contact) bearings is the almost complete elimination of friction. Therefore， the main function of antifriction-bearing lubricants is to help prevent corrosion and dirt contamination. corrosion 腐蝕 dirt contamination 灰塵污染 Since some friction does exist， especially between the rolling elements and their separator， the lubricant must also remove the heat caused by this sliding action. separator 保持架 remove the heat As a result， although there is minimal friction present， a lubricant is still absolutely essential. Fatigue， which is the cause of failure of a properly lubricated antifriction bearing， is a stress reversal phenomenon which takes place on the contacting surfaces of the raceways and rolling elements. a stress reversal 交變應(yīng)力 Hence， the life of an antifriction bearing is measured by the number of shaft revolutions which occur prior to fatigue failure. is measured by…. : 以…. 來(lái)衡量 shaft revolutions: 軸的旋轉(zhuǎn) prior to: 在…..之前 The greater the bearing load， the shorter will be its life in revolutions; also， the greater the shaft speed， the shorter will be its life in revolutions; also， the greater the shaft speed， the shorter will be the bearing life. Since fatigue is a statistical occurrence， the percent probability of failure must also be considered. a statistical occurrence: 統(tǒng)計(jì)學(xué)應(yīng)考慮的事情 percent probability: 百分比概率 It is essential to know the advantages and disadvantages of the various types of bearings， as well as their salient features. salient features : 突出的特點(diǎn) For example， ball and roller bearings can be of the self- aligning type to allow for shaft misalignment and deflections. self-aligning type: 自定位型 Also， shields and seals are available to protect the bearing from foreign contaminants. shields and seals： 防塵罩與密封圈 foreign contaminants： 外來(lái)污染物 Some antifriction bearings contain a permanently sealed lubricant which is administered by the manufacturer and lasts for the life of the bearing. 一些滾動(dòng)軸承有永久密封在內(nèi)的潤(rùn)滑劑，這些潤(rùn)滑劑是由制造商給予的并在軸承壽命期內(nèi)連續(xù)使用。 be appropriate for ….: 對(duì)....適合 installation: 裝置，設(shè)置，安裝，配合 inner race: 內(nèi)圈 outer race: 外圈 rub: 摩檫 ubiquitous: 普遍存在，處處都有 diverse: 各種各樣的 Bearing are used to hold shafts that must rotate relative to supports that are fixed – for instance， the housing of a motor， gearbox， or transmission. A wide variety of bearings exist， which are classified into two broad groups – rolling contact and journal. Each particular type is appropriate for a different set of installation and operating conditions. In this section we discuss only rolling contact bearing. Rolling contact bearings typically comprise an inner race; an outer race; rolling elements in the form of balls， cylinders， or cones; and a separator that prevents the rolling elements from rubbing against one another. They are ubiquitous in machine design， and are found in applications as diverse as bicycle wheels， robotic joins， and automobile transmissions. A sample installation of a rolling contact bearing is illustrated in Figure 4.9. the shaft and the bearing’s inner race rotate together， while the out race and the transmission’s housing are stationary. 減譯法 所謂減譯，即把英語(yǔ)原文中的一些詞如冠詞、代詞和介詞等在譯成漢語(yǔ)時(shí)可省略不譯。 在下面三種情況中所省略的詞語(yǔ)在英語(yǔ)中是必不可的。但譯成漢語(yǔ)是多余的，常采用減譯：英語(yǔ)句子中，有的詞從語(yǔ)法結(jié)構(gòu)上講是必不可少的，但并無(wú)什么實(shí)際意義， 只是在句中起單純的語(yǔ)法作用；有的詞在英語(yǔ)中用的非常普遍，但在漢語(yǔ)中卻很少使用甚至根本不用；有的詞或成分如果照字面一一譯出又顯得多余、累贅，甚至?xí)�造成譯文邏輯不通或修辭不當(dāng)。 冠詞的減譯： 英語(yǔ)冠詞是附在普通名詞前的一種虛詞，是使用頻率最高的功能詞之一，但其本身沒(méi)有獨(dú)立的詞匯意義，只對(duì)名詞起限定和輔助說(shuō)明的作用。漢語(yǔ)中沒(méi)有冠詞，也沒(méi)有與之相應(yīng)的詞類，因此在將英語(yǔ)譯成漢語(yǔ)時(shí)，除少數(shù)情況外，冠詞一般都應(yīng)減去不譯。例如： A liquid metal becomes a gas at or above its boiling point. 在沸點(diǎn)或沸點(diǎn)以上，金屬液會(huì)變成氣體。 但有兩種情況例外：當(dāng)不定冠詞具有明顯的數(shù)字概念或與單數(shù)可數(shù)名詞連用，表示單位數(shù)量時(shí)，一般必須譯出。例如： Double ladling is an old method and used only to a limited extent. 雙包法是一種古老的方法，它僅在一個(gè)有限的范圍內(nèi)使用 （2）定冠詞在起著特指某具體事物的作用時(shí)，通常也必須譯出。例如： The ease with which the two surfaces “wet” each other， and the composition of the initial charge and the temperature will determine the carbon solubility in the iron. 這兩個(gè)表面互相“濕潤(rùn)”的容易程度，初始爐料的化學(xué)成分以及溫度，將決定碳在鐵中的溶解度。介詞的減譯： 英語(yǔ)介詞豐富，使用頻繁。它通過(guò)用來(lái)表示名詞或代詞等和句中其他詞之間的關(guān)系。漢語(yǔ)中也有介詞，但數(shù)量有限，使用也不多，詞與詞之間的關(guān)系主要是通過(guò)詞序和意會(huì)來(lái)區(qū)分。因此在英譯漢時(shí)，介詞除了轉(zhuǎn)譯為漢語(yǔ)等詞類外，減譯的情況較多。例如： It is necessary to develop our computer science at high speed. 必須高速發(fā)展我國(guó)的計(jì)算機(jī)科學(xué)。 What is the different between a mixture and a compound? 混合物與化合物的區(qū)別何在？連詞的減譯： 英語(yǔ)在句法構(gòu)造上采用形合法，所以連詞在英語(yǔ)中使用頻率較高。漢語(yǔ)的句法構(gòu)造主要采用意合法，故連詞用得較少。多數(shù)漢語(yǔ)句子是按時(shí)間順序和邏輯關(guān)系排列的，語(yǔ)序固定，各成分之間 的關(guān)系較清楚，因此在英譯漢時(shí)，往往可以，有時(shí)甚至必須將英語(yǔ)中的某些連詞減譯。例如： These metals usually require a certain amount of preheating before welding and then allowed to cool slowly after the weld is completed. 這些金屬通常要求在焊接前進(jìn)行一定的預(yù)熱，在焊接完成后緩慢冷卻 （2）Give him an inch， and he will take a mile. 他得寸進(jìn)尺。代詞的減譯：人稱代詞的減譯：在一段文字中，如果緊連的兩個(gè)句子主語(yǔ)相同，漢語(yǔ)習(xí)慣其中一句可以不用主語(yǔ)。而英語(yǔ)則每句必有主語(yǔ)，常在后一句中用人稱代詞表示和前句相同的主語(yǔ)這樣使用的英語(yǔ)人稱代詞則減譯。例如： When carbon burns it unites with oxygen from the air. 碳燃燒時(shí)與空氣中的氧結(jié)合。 人稱代詞中的we和you，在專業(yè)文章中往往是泛指，具有“概括”或“不定”的意義，翻譯時(shí)大多不需譯出。 Before you begin to work the instrument， first read the instruction carefully. 在開(kāi)始使用本儀器前，請(qǐng)首先仔細(xì)閱讀說(shuō)明書。 Given the weight and the specific gravity of a body， we can calculate its volume. 給出物體的重量和密度，就能求出其體積。物主代詞的減譯： 英語(yǔ)中的物主代詞一般不能省略。而漢語(yǔ)中在關(guān)系已經(jīng)明確的情況下不必再用物主代詞來(lái)明確所屬關(guān)系。因此漢譯時(shí)減譯英語(yǔ)物主代詞的情況十分常見(jiàn)。例如： Ventilation is one way of reducing emissions in the workshop， however， you cannot depend on this alone to solve your dust problem. 反身代詞的減譯 根據(jù)漢語(yǔ)的習(xí)慣，某些作賓語(yǔ)或同位語(yǔ)的反身代詞往往是可以減譯的。不定代詞、連接代詞也�？蓽p譯。例如： Like zinc， iron also converts itself into a vapor at high temperature. 像鋅一樣，鐵在高溫下也會(huì)變成蒸汽。（反身代詞itself減譯） 同義詞或近義詞的減譯： 在專業(yè)英語(yǔ)著作中，常有兩個(gè)同義詞連用的現(xiàn)象，即對(duì)同一概念用兩個(gè)詞重復(fù)表達(dá)。這兩個(gè)詞中前一個(gè)往往是專業(yè)詞匯，后一個(gè)往往是普通詞匯。兩者在語(yǔ)法上是同位關(guān)系，�？捎眠B詞“or”連接。作者這樣做往往是出于強(qiáng)調(diào)或?yàn)榱诉m應(yīng)不同層次讀者的需要。但在譯成漢語(yǔ)時(shí)，為了使概念準(zhǔn)確，避免文字重復(fù)或含糊不清，只需要譯出其中一個(gè)漢語(yǔ)中通用的名稱就可以了。例如： The force of gravity acts vertically downwards and gives an object “weight or heaviness”. 重力垂直向下作用，使物體具有“重量”。（weight和heaviness重復(fù)，減譯） 上面介紹了減詞譯法常見(jiàn)的一些情況，可見(jiàn)其應(yīng)用十分廣泛。減譯的目的是為了使譯文簡(jiǎn)潔明快、嚴(yán)謹(jǐn)精煉，即達(dá)到所謂“削枝強(qiáng)干”。 減譯后的譯文雖然在詞量上和原文不盡一致，但在意思和精神上都應(yīng)該和原文一樣是絕對(duì)完整的，即所謂“減詞不減意”。在使用減詞法時(shí)值得注意的是，在減譯中決不能更改或漏譯原文的內(nèi)容，更不能“濫砍濫伐”，借減譯之名隨意刪去難懂難譯的詞句。 A shaft is a rotating or stationary member， usually of circular cross section， having mounted upon it such elements as gears， pulleys， flywheels， cranks， sprockets， and other power transmission elements. Shafts may be subjected to bending， tension， compression， or torsional loads， acting singly or in combination with one another. When they are combined， one may expect to find both static and fatigue strength to be important design considerations， since a single shaft may be subjected to static stresses， completely reversed， and repeated stresses， all acting at the same time. The word “shaft” covers numerous variations， such as axles and spindles. An axle is a shaft， either stationary or rotating， not subjected to torsion load. A short rotating shaft is often called a spindle. When either the lateral or the torsional deflection of a shaft must be held to close limits， the shaft must be sized on the basis of deflection before analyzing the stresses. The reason for this is that， if the shaft is made stiff enough so that the deflection is not too large， it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are safe; it is almost always necessary to calculate them so that he knows they are within acceptable limits. Whenever possible， the power-transmission elements， such as gears or pulleys， should be located close to the supporting bearings. This reduces the bending moment， and hence the deflection and bending stress. Lesson 6 Engineering Tolerancing Designers typically specify a component’s nominal dimensions such that it fulfils requirements. 1. typically : 特有地，獨(dú)特地，典型地 通常地 2. specify: 規(guī)（指，給，確）定 3. nominal dimension: 公稱尺寸 In reality， components cannot be made repeatedly to nominal dimensions， due to surface irregularities and the intrinsic surface roughness. in reality: in fact 實(shí)際上 Some variability in dimensions must be allowed to ensure manufacture is possible. variability：變化 However， the variability permitted must not be so great that the performance of the assembled parts is impaired. the performance of the assembled parts：裝配件的工作性能 The allowed variability on the individual component dimensions is called the tolerance. The term tolerance applies not only to the acceptable range of component dimensions produced by manufacturing techniques， but also to the output of machines or processes. 1. applies to: 適用于 2. the acceptable range of component dimensions: 3. process: 過(guò)程，處理，加工 For example， the power produced by a given type of internal combustion engine varies from one engine to another. internal combustion engine：內(nèi)燃機(jī) In practice， the variability is usually found to be modeled by a frequency distribution curve， for example the normal distribution (also called the Gaussian distribution). 1. a frequency distribution curve: 頻率分配曲線 2. the normal distribution( the Gaussian distribution)：正態(tài)分布（高斯分布）譯：實(shí)際上，我們常常發(fā)現(xiàn)這種變化模型是頻率分配曲線…… One of the tasks of the designer is to specify a dimension on a component and the allowable variability on this value that will give acceptable performance. Control of dimensions is necessary in order to ensure assembly and interchangeability of components. interchangeability: 互換性 Tolerances are specified on critical dimensions that affect clearances and interference fits. 1. critical dimensions: 關(guān)鍵尺寸 2. clearances and interference fits: 間隙與過(guò)盈配合 Tolerances on critical dimensions that affect clearances and interference fits are specified. One method of specifying tolerances is to state the nominal dimension followed by the permissible variation， so a dimension could be stated as 40.000±0.003mm. state: 指(標(biāo))出，表明， 確(指，規(guī))定 be stated as: 用….表示 This means that the dimension should be machined so that it is between 39.997 and 40.003 mm. Where the variation can vary either side of the nominal dimension， the tolerance is called a bilateral tolerance. a bilateral tolerance: 雙向公差 For a unilateral tolerance， one tolerance is zero， e.g.40.000 +0.006. a unilateral tolerance: 單向公差 Most organizations have general tolerances that apply to dimensions when an explicit dimension is not specified on a drawing. 1. organizations: 機(jī)構(gòu)，組織 2. general tolerances: 通用公差 3. explicit : 明白(顯，確，晰)的，清楚的 explicit function 顯函數(shù) For machined dimensions a general tolerance may be ±0.5 mm. So a dimension specified as 15.0 mm may range between 14.5 mm and 15.5mm. Other general tolerances can be applied to features such as angles， drilled and punched holes， castings， forgings， weld beads and fillets. punched holes: 沖孔 When specifying a tolerance for a component， reference can be made to previous drawings or general engineering practice. 1. make a reference to :參考….. 2. general engineering practice: 一般工程慣例 Tolerances are typically specified in bands as defined in British or ISO standards. The table gives a guide for the general applications of tolerances. 1. a guide : 向?qū)�，指南，入門 2. the general applications of tolerances: 一般公差應(yīng)用 For a given tolerance， e.g. H7/s6， a set of numerical values is available from a corresponding chart for the size of component under consideration. 1. a set of numerical values: 一組數(shù)值 2. a corresponding chart: 對(duì)應(yīng)的圖表 3. the size of component under consideration: 正在考慮的零件尺寸 The section following gives specific examples of this for a shaft or cylindrical spigot fitting into a hole. 1. specific examples : 具體例子 2. cylindrical spigot: 柱形銷 A standard engineering task is to determine tolerances for a cylindrical component， e.g. a shaft， fitting or rotating inside a corresponding cylindrical component or hole. The tightness of fit will depend on the application. For example， a gear located on to a shaft would require a “tight” interference fit， where the diameter of the shaft is actually slightly greater than the inside diameter of the gear hub in order to be able to transmit the desired torque. Alternatively， the diameter of a journal bearing must be greater than the diameter of the shaft to allow rotation. alternatively: 換句話說(shuō)，另一方面，要不 Given that it is not economically possible to manufacture components to exact dimensions， some variability in sizes of both the shaft and hole dimension must be specified. However，the range of variability should not be so large that the operation of the assembly is impaired. Rather than having an infinite variety of tolerance dimensions that could be specified， national and international standards have been produced defining bands of tolerances， examples of which are listed in Table ， e.g. H11/C11. To turn this information into actual dimensions corresponding tables exist， defining the tolerance levels for the size of dimensions under consideration. In order to use this information the following list and Fig. 6-1 give definitions used in conventional tolerancing. Usually the holebased system is used， as this results in a reduction in the variety of drill， reamer， broach and gauge tooling required within a company. variety: 變化，種類，品種 Size: a number expressing in a particular unit the numerical value of a dimension. a particular unit: 專用單位 Actual size: the size of a part as obtained by measurement. Limits of size: the maximum and minimum sizes permitted for a feature. feature: 特點(diǎn)，性能， 特征， 零部件 Maximum limit of size: the greater of the two limits of size. Minimum limit of size: the smaller of the two limits of size. Basic size: the size by reference to which the limits of the size are fixed. by reference to: 參考(照，看) Deviation: the algebraic difference between a size. Actual deviation: the algebraic difference between the actual size and the corresponding basic size. Upper deviation: the algebraic difference between the maximum limit of size and the corresponding basic size. Lower deviation: the algebraic difference between the minimum limit of size and the corresponding basic size. Tolerance: the difference between the maximum limit of size and the minimum limit of size. Shaft: the term used by convention to designate all external features of a part. by convention: 按照慣例 Hole: the term used by convention to designate all internal features of a part. 2. Fit Fits are concerned with the relationship between two parts. Consider a shaft and hole combination: if the shaft is larger than the hole， the condition is said to be of interference; and if smaller than the hole， the condition is said to be of clearance. In order that the precise condition is ensured， the limits of size of both the shaft and the hole must be stipulated. Fits can be classified as follows: clearance fit， interference fit， and transitional fit. Hole-based system and shaft-based system In order to obtain a range of degrees of clearance， and thedegrees of interference， it is necessary to use a wide variation of hole sizes and shaft sizes. For example， a manufacturing company could be making a number of parts， all of a nominal 25 mm diameter， but which all slightly different in actual limits of size， to suit the actual fit required of each pair of parts. This situation could mean that a large number of drills， reamers， gauges， etc. were required It is logical that， to reduce this number， a standard hole could be used for each nominal size， and variation of fit be obtained by making the mating shaft smaller or larger than the hole. This is known as a hole-based system. Exercise 6 Translate the following sentences into Chinese: (1)Since it is impossible to machine a part to an exact size， a designer must specify an acceptable range of size that will permit the part to fit and function as intended. 2）The maximum and minimum sizes in part dimensions that are acceptable are limits between which the actual part dimension must fall. 3）Tolerance on drawing is often indicated by specifying a limit， or by plus and minus notations. With plus and minus tolerancing， when the tolerance is both above and below the nominal (true theoretical ) size， it is said to be bilateral (two sides). 4）Although a machinist is not usually concerned with establishing tolerance and limit specifications， you can easily see how fit problems can be created by overlapping tolerances discussed in this example. 5) Many times a machinist is concerned with press or interference fits. In this case two parts are forced together usually by mechanical or hydraulic pressing. 6) Although standardized measurement is essential to modern industry， perhaps even more important are the design specifications that indicate the dimension of a part. Lesson 7 Lathes The lathe removes material by rotating the workpiece against a cutter to produce external or internal cylindrical or conical surfaces. conical ：圓錐的 Parts to be machined can be held between centers， attached to a faceplate， supported in a jaw chuck， or held in a draw-in chuck or collet. 1. center: n. 中心，頂尖 v. 定中心，找中心，打中心孔 2. faceplate：面板，花盤 3. a jaw chuck： 帶爪卡盤 4. a draw-in chuck: 內(nèi)拉卡盤 5. collet: 筒夾 Though this machine is particularly adapted to cylindrical work， It is also commonly used for the production of flat surfaces by facing， in which the workpiece is rotated while the cutting tool is moved perpendicularly to the axis of rotation. cylindrical work :外圓加工 facing: 端面加工 perpendicular to：垂直于…. parallel to: 平行于…… Plain surfaces can be obtained by supporting the work on a faceplate or in a chuck. plain:簡(jiǎn)單的，清楚的，普通的，平滑的， Work held in this manner can likewise be centered， drilled， bored， or reamed. likewise: adv 同樣，也，又 In addition， the lathe can be used for cutting threads and turning tapers; with the proper attachments， it can be adapted to simple milling or grinding operations. 1. in addition :此外 2. thread: 螺紋 3. attachments :輔助裝置 4. milling:銑削 5. grinding:磨削 It is probably the oldest of all the machine tools as well as the most important machine in modern production. machine tools: 機(jī)床 The engine lathe is the basic turning machine from which other turning machines have been developed. engine lathe: 普通車床 turning machines， lathe : 車床 The drive motor is located in the base and drives the spindle through a combination of belts and gears， which provides the spindle speeds from 25 to 1500 rpm. base: 基座 belt: 皮帶 The spindle is a sturdy hollow shaft， mounted between heavy-duty bearings， with the forward end used for mounting a drive plate to impart positive motion to the workpiece. sturdy : 堅(jiān)固的， 結(jié)實(shí)的 heavy-duty : 重型的 drive plate: 驅(qū)動(dòng)盤 impart …. to : 把…給予 ; 把….傳給 positive motion : 確動(dòng) The drive plate may be fastened to the spindle by threads， by a cam lock mechanism， or by a threaded collar and key. thread : 螺紋 a cam lock mechanism : 凸輪鎖定機(jī)構(gòu) a threaded collar and key : 螺紋凸緣與鍵 The turret lathe is basically an engine lathe with certain additional features to provide for semiautomatic operation and to reduce the opportunity for human error. The carriage of the turret lathe is provided with T-slots for mounting a tool-holding device on both sides of the lathe ways with tools properly set for cutting when rotated into position. carriage: 拖板 tool-holding device: 刀具夾緊裝置 The carriage is also equipped with automatic stops that control the tool travel and provide good reproduction of cuts. The tailstock of the turret lathe is of hexagonal design， in which six tools can be mounted . tailstock : 尾架 Although a large amount of time is consumed in setting up the tools and stops for operation， the turret lathe， once set， can continue to duplicate operations with a minimum of operator skill until the tools become dulled and need replacing. setting up: 安裝，調(diào)整 Thus， the turret lathe is economically feasible only for production work， where the amount of time necessary to prepare the machine for operation is justifiable in terms of the number of part to be made. in terms of ：從….觀點(diǎn)來(lái)看; 在….方面 (意義) (上) Tracing and duplicating lathes are equipped with a duplicating device to automatically control the longitudinal and cross feed motions of the single-point cutting tool and provide a finished part of required shape and size in one or two passes of the tools. passes of the tools: 走刀 The single-spindle automatic lathe uses a vertical turret as well as two cross slides. cross slide: 橫拖板 The work is fed through the machine spindle into the chuck， and the tools are operated automatically by cams. chuck: 卡盤 The multispindle automatic lathe is provided with four， five， six， or eight spindles， with one workpiece mounted in each spindle. The spindles index around a central shaft， with the main tool slide accessible to all spindles. Each spindle position is provided with a side tool-slide operated independently. Since all of the slides are operated by cams， the preparation of this machine may take several days， and a production run of at least 5000 parts is needed to justify its use. justify: 證明…..是正當(dāng)(正確，合理)的; 認(rèn)為…..有理由 The principal advantage of this machine is that all tools work simultaneously， and one operator can handle several machines For relatively simple parts， multispindle automatic lathes can turn out finished products at the rate of 1 every 5 sec. turn out : 生產(chǎn) finished products : 成品 Exercises 5 The concern of a machine designer with ball and roller bearings is fivefold as followings: (a) life in relation to load; (b) stiffness， i.e. deflections under load; (c) friction; (d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will usually secure satisfactory performance. The deflection of the bearing elements will become important where loads are high， although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants， and sealing arrangements must be chosen with regard to the hostility of the environment. Exercises 7 Translate the following passage into Chinese: A machine tool performs three major functions: (1) it rigidly supports the workpieces or its holder and the cutting tool; (2) it provides relative motion between the workpiece and the cutting tool; (3) it provides a range of feeds and speeds. Machines used to remove metal in the form of chips are classified in four general groups: those using single-point tools， those using multipoint tools， those using random-point tools (abrasive)， and those that are considered special. Machines using basically the single-point cutting tools include: (1) engine lathes， (2) turret lathes， (3) tracing and duplicating lathes， (4) single-spindle automatic lathes， (5) multi-spindle automatic lathes， (6) shapers and planers， (7) boring machines. Machines using multipoint cutting tools include: (1) drilling machines， (2) milling machines， (3) broaching machines， (4) sawing machines， (5) gear-cutting machines. Machines using random-point cutting tools include: (1) cylindrical grinder， (2) centreless grinders， (3) surface grinders. Special metal removal methods include: (1) chemical milling， (2) electrical discharge machining， (3) ultrasonic machining. the maximum size of bar stock gear box a V-belt or silent-chain drive carbide and ceramic tools the inner ways of the bed tailstock quill a graduated scale in the direction normal to the axis of rotation of the work manual movement of the carriage per revolution of the spindle Translate the following sentences into Chinese: 1. The main components of a lathe are the headstock and tailstock at opposite ends of a bed， and a tool-post between them which holds the cutting tool. 2. The size of a lathe is designated by two dimensions. The first is known as the swing. This is the maximum diameter of work that can be rotate on a lathe. The second size dimension is the maximum distance between centers. 3. Although engine lathe are versatile and useful because of the time required for changing and setting tolls and for making measurements on the workpiece， they are not suitable for quantity production. 4. However， much of the operator’s time is consumed by simple， repetitious adjustments and in watching chips being made. 5. Consequently， to reduce or eliminate the amount of skilled labor that is required， turret lathes， screw machines， and other types of semiautomatic and automatic lathes have been highly developed and are widely used in manufacturing. A machine tool performs three major functions: (1) it rigidly supports the workpieces or its holder and the cutting tool; (2) it provides relative motion between the workpiece and the cutting tool; (3) it provides a range of feeds and speeds. holder : 夾具，夾持器，保持架，支架 feed ：v. 喂食，進(jìn)給 n. 進(jìn)給量 Machines used to remove metal in the form of chips are classified in four general groups: those using single-point tools， those using multipoint tools， those using random-point tools (abrasive)， and those that are considered special. single-point : 單刃 multipoint : 多刃 random ：任意的，隨機(jī)的，不規(guī)則的 abrasive ：磨粒 chip: 片，切屑 Machines using basically the single-point cutting tools include: (1) engine lathes， (2) turret lathes， (3) tracing and duplicating lathes， (4) single-spindle automatic lathes， (5) multi-spindle automatic lathes， (6) shapers and planers， (7) boring machines. engine lathes 車床 turret lathes 轉(zhuǎn)塔車床 tracing and duplicating lathes 仿形車床 shapers and planers 牛頭刨床與龍門刨床 boring machines 鏜床 Machines using multipoint cutting tools include: (1) drilling machines， (2) milling machines， (3) broaching machines， (4) sawing machines， (5) gear-cutting machines. broaching machines：拉床 sawing machines： 鋸床 Machines using random-point cutting tools include: (1) cylindrical grinder， (2) centreless grinders， (3) surface grinders. cylindrical grinder：外圓磨床 centreless grinders： 無(wú)心磨床 surface grinders：平面磨床 Special metal removal methods include: (1) chemical milling， (2) electrical discharge machining， (3) ultrasonic machining. chemical milling ：化學(xué)蝕刻 electrical discharge machining：放電加工 ultrasonic machining：超聲波加工Sex紅軟基地

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