机械工程专业英语翻译PPT课件下载

这是一个关于机械工程专业英语翻译PPT课件，主要介绍机械工程的专业英语的相关内容。机械工程 专业英语课程介绍学习专业英语的重要性学习目的为何在大三开设这门课程专业英语的英文名称“专业英语”----- English for Special Purpose Specified English for ……. “机械工程专业英语” Specified English for Mechanical Engineering 专业英语和普通英语的区别 一. 词义特点 1. 根据词类辨明词义 e.g: (1) Round (adj.) surface reflector is a key unit for the solar energy device. 曲面反射器是太阳能装置的关键元件。 ( 2) This is the whole round (n.) of knowledge. 这是全部知识范围。 2. 区分场合确定词义（不同的场合，词义也不一样。要根据 上下文和语言环境来确定词义） e.g: (1) pig: 猪 ~ iron 生铁 (机械专业) ~ metal 金属锭 ~ copper 生铜 (2) dog: 狗 (机械专业) ~ 鸡心夹头, 挡块 3. 按照习惯搭配词义 e.g: (1) I have a short memory. (2) This biscuit eats short. (3) Indeed he has a short temper. 4. 联系上下文活用词义 e.g: (1) There is no physical contact between tool and workpiece. 工具和工件之间没有有形（直接）的接触。 (2) High-speed grinding does not know this disadvantage 高速磨削不知道（存在）这个缺点，欢迎点击下载机械工程专业英语翻译PPT课件哦。

机械工程专业英语翻译PPT课件是由红软PPT免费下载网推荐的一款学校PPT类型的PowerPoint.

机械工程 专业英语课程介绍学习专业英语的重要性学习目的为何在大三开设这门课程专业英语的英文名称 “专业英语”----- English for Special Purpose Specified English for ……. “机械工程专业英语” Specified English for Mechanical Engineering 专业英语和普通英语的区别 一. 词义特点 1. 根据词类辨明词义 e.g: (1) Round (adj.) surface reflector is a key unit for the solar energy device. 曲面反射器是太阳能装置的关键元件。 ( 2) This is the whole round (n.) of knowledge. 这是全部知识范围。 2. 区分场合确定词义（不同的场合，词义也不一样。要根据 上下文和语言环境来确定词义） e.g: (1) pig: 猪 ~ iron 生铁 (机械专业) ~ metal 金属锭 ~ copper 生铜 (2) dog: 狗 (机械专业) ~ 鸡心夹头， 挡块 3. 按照习惯搭配词义 e.g: (1) I have a short memory. (2) This biscuit eats short. (3) Indeed he has a short temper. 4. 联系上下文活用词义 e.g: (1) There is no physical contact between tool and workpiece. 工具和工件之间没有有形（直接）的接触。 (2) High-speed grinding does not know this disadvantage 高速磨削不知道（存在）这个缺点。 二. 句子结构特点 1. 句子长 2. 被动语态多 e.g: The rate at which work is done is called power. 3. 后置定语多 4. 名词化结构多 e.g: to control the machine ---- the control of the machine 学习方法与教学方法工具书的介绍 1. 收词不足，收词量有限 2. 收词面广 3. 例证丰富 4. 释义地道， 全面 5. 词的用法说明较详细 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 对…..比对…..更兴趣 2. under load ：承载时 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: 某个设计 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: 测定的大小 2. response to: 对…..的反应 In engineering materials the properties are recorded in handbooks or， for new materials， are made available by the supplier. make sth. + 形容词(sth. be make =形容词): 使….怎么样 the properties are made available : 使……可获得 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: 室温状态 2. the actual service conditions：实际工作状态 3. elevated temperatures：高温 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 : 称为 2. (as) compared to (with): 与…相比， 同….比较起来， 与…相对应 3. structure sensitive， structure-insensitive properties 结构敏感性， 结构不敏感性 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: 导热性与导电性 specific heat: 比热 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: 拉伸强度和屈服强度 2. impact， creep， and fatigue resistance: 抗冲击性，抗蠕性，抗疲劳性 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…. 认出，识别， 考虑 (认识) 到 some sources maintain: 一些资料(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: 载荷大小 2. geometry of notch in impact testing: 试验中缺口的几何形状 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: 所报道的测量值 2. statistical averages: 统计平均值 3. commercial material: 商用材料 4. tolerance band: 公差带 5. deviation from: 与….的偏差 6. a given published value: 某个公布的值 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 : 称为; 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: 导热性与导电性 2. specific heat: 比热 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 抗冲击性，抗蠕变性和抗疲劳性 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: 随着….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: 超过或不足 2. structural bonds: 结构键 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: 高电子迁移率 2. the conductors with high electron mobility :高电子迁移率的导体 3. the insulators with no free electrons: 无自由电子的绝缘体 4. semiconductors that can have a planned modification of their electron mobility 有计划改变电子迁移的半导体 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: 固态光学器件 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: 结合力 2. aggregations of atoms: 原子团 3. in terms of: 用….语言来…. 专业英语的特点专业英语（specified English）是在自然科学和工程技术的专业领域中使用的一种英语文体。它是在专业技术的不断发展中逐渐形成并与专业技术同步发展的。由于专业技术的要求语言表述能客观、严谨地反映科学研究的内容，所以，专业英语的特点，除了包含一些实验数据、公式推导和数学符号以外，在词汇含义、语法结构、句型使用和修辞手法等方面与日常英语、文学英语有不同的特点。这诚如著名科学家钱三强指出的：专业英语“无论在语法结构或词汇方面都逐渐形成它特有的习惯用法、特点与规律”。不学习和掌握这些特点与规律，就很难搞好专业英语的阅读、翻译和写作。为了掌握这些特点和规律，本章及下一章节将主要介绍专业英语的语法特点和词汇特点。 一．专业英语的语法特点 1． 无人称（Impersonal）（无生命的第三人称语气或非人称语气） 科技文体第一个显著的特点就是较多地使用无生命的第三人称语气。 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. 凡需要精确控制运动的地方，步进电机都非常有用。他们广泛用于机器 人技术，打印机， 绘图仪和计算机磁盘驱动器，这些需要精确的定位或速度。 2．被动语态 ( Passive Voice ) 由于专业英语文献侧重叙事和推理，陈述的对象是客观事物。读者重视的是作者的观点和发明的内容，而不是作者本人。因此在语言表述中必然较多地使用以客观事物为主体的被动语态。 专业英语中的被动语句不一定要说出行为主体，特别当行为主体是人 时。但有时也用“by”引出行为者。这些行为者除了人、机构、物质以 外 ，还包括完成该动作的方法、原因或过程等。例如： The temperature of the liquid is raised by the application of heat. 加热可以提高液体温度。 The rate at which work is done is called power. 3．非谓语动词 动词非谓语形式有：动名词、分词、动词不定式及它们的复合结构。 专业英语中，动词的非谓语形式应用广泛，这是因为专业英语要求准确、精炼，而动词的非谓语形式可以很好地实现这些要求。比如采用这一形式能用扩展的成分对所修饰的词进行严格的说明和限定。其中每一个分词定语都能代替一个从句，从而可使很长的句子匀称， 避免复杂的主从符合结构，并省略动词时态的配合，使句子即不累赘又语意明确。 3. 1 分词的使用 在专业英语中，分词短语被大量地用作定语、状语和独立分词结构，取代被动态或主动态的关系从句，使句子结构得到简化。例如： 1. Rammers driven by compressed air can increase the production rates. 压缩空气驱动的舂砂器可以提高生产效率。 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. 自动螺丝车床最初是用来对螺钉和类似的带有螺纹的零件进行自动 化快速加工的。但是，这种车床的用途早就超过了这个狭窄的范围。现 在，它在许多种类的精密零件的大批量生产中起着重要的作用。 分词独立结构，即： 名词或代词＋分词短语，是一种主谓结构，在句 中的作用相当于并列分句或从句。例如： 3. Agitation is critical， the aim being to distribute silicon carbide particles homogeneously throughout the aluminum melt. 搅拌至关重要，其目的是将碳化硅颗粒均匀地分布在整个铝液中。 分词独立结构前加with (without) 变成起状语作用的介词短语，用于当 分词的逻辑主语与句子主语不一致时。 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. 在高炉热交换器中，空气流过外管，燃气流过内管，热交换通过管 壁进行。 3. 2 动名词的使用 动名词构成的介词短语可取代状语从句或简化陈述句，在英语中广泛 应用。例如： In redesigning an experimental part for production， economical tolerances should be used. 为了生产而重新设计试件时， 必须使用经济公差。 3. 3 不定式的使用 不定式在专业英语中的使用也十分频繁，在句中常用来替换表示目的功能的从句，使句子结构简练。例如： 1. To insure manufacture quality of electrodes， the American Welding Society has set up certain requirements for electrodes. 为了确保电极的制造质量，美国焊接学会规定了电极必须具备的一些条件。 2. There is high requirement of skill in carrying out this operation to produce products with high performances. 进行这项操作时需要很高的技巧，以生产出具有高性能的产品。 4. 名词化结构 “表示动作意义的名词＋of＋名词＋修饰语”叫做名词化结构。名词化结构具有文字明了、用词简洁、结构紧凑、表意客观、信息容量大等特点，在专业英语中经常用它代替主、谓结构作各种句子成分，使句子结构简化。例如: 用普通英语表达这样一句话： 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. 用名词化结构如下表述： 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. 金属超声波探伤是将超声振动施于具有弹性的材料，并观察振动在材料中产生的作用。 二．专业英语的词汇特点专业英语词汇的组成专业技术词汇： polymerization 聚合作用 diathermometer 热阻测定仪 mechatronics 机电一体化，机械电子学 lathe 车床半专业技术词汇： power 力量， 权力 （日常英语） 动力 （机械专业） 电力 （电力专业） 幂 ( 数学专业） 功率 （物理专业） 爆发力 （体育专业） 构词法 英语的构词法包括转化、合成、派生三种形式。转化 (conversion) 如： melt 熔液——to melt熔化 finish光洁度——to finish精加工、抛光 alloy 合金——to alloy 使成合金复合法 (composition) 如： waveform 波形 ballbearing 滚珠轴承 workshop 车间 toolroom 工具室派生或词缀 (derivation) 如： unavoidable 不可避免的 inaccuracy 不精确 词汇缩略首字词缩略: 它是由原词组的每个词首字母组成，在阅读中首字词要逐字母读.例如： NC 数控 AC 自适应控制 PLC 可编程控制器 AIEE American Institute of Electrical (Electronic) Engineers 美国电气（电子）工程师学会 首字词拼音: 把一个词组中的首字母拼凑成一个词.例如 laser — light amplification by stimulated emission of radiation 激光 ROM —— read only memory 只读存储器 AIDS —— acquired immune deficiency syndrome 爱滋病 节略词: 某些词使用频率高，为了方便，在发展过程逐渐用 它们的前几个字母来表示。例如： ref. —— reference 参考文献 lab. —— laboratory 实验室 in. —— inch 英吋 ft. —— foot 英呎 缩写词 例如： etc. — et cetera 等等 i.e — that is 即 e.g. — for example 例如 vs. — versus 对… 拼缀: 即以组成复合词的各个词中各抽取一或两个词缀相 拼合。例如： transeiver ( transistor ＋ receiver) 收发机 mechatronics ( mechanics ＋ electronics) 机电一体化 distinguish 区别；区分 distort: 变形 by means of : 借助于 permanent: 永久的 coefficient: 系数 steel mill: 钢厂 expansion ：膨胀 roll: 轧锟 react to: 对….起作用; 对….的反应 crack: 裂开，裂纹，破裂 in connection with: 与…..有关 gradually: 逐渐地 five broad categories: 五大类 elasticity: 弹性 ductility: 延展性 toughness: 韧性 elevator: 升降机 cable: 电缆 beam: 横梁 penetration: 压痕，凹痕 abrasion: 磨损 elongate: 延长，伸长 Lesson 2 Metals and Ferrous Metals ferrous a. 铁类的，黑色的 nonferrous a. 有色的 two general types 两大类 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: 不同数量的 Steel and cast iron are the most common ferrous metals in general use. cast iron 铸铁 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: 各种各样的，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 + 强调部分 + 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→金属种类 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： 从事 other than：除了…….. be known as……: 叫做，称为 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 ….. 设计成能(做)， 用来…， 目的是使… be designed for….. 用做…用途; 为….而设计 specific: a. 1.比率，单位的 e. g: specific heat， specific weight 2. 特殊(定，有，种)的; 专门的; 具体的，明确的 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 热加工工具钢 cold work tool steels 冷加工工具钢 special-purpose 专用的 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 扁钢 rod 圆钢 by rolling the steel into shape 轧制成形的方法…. 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: 轧锟 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 淡蓝色的氧化层 This steel is fairly uniform in quality and is used for many different kinds of parts. uniform a. 均匀 Hot-rolled bars of the best quality are used to produce cold-finished steels. cold-finished steels 冷精轧钢 Cold- finished steels are used when great accuracy， better surface finish， and certain mechanical properties are needed. surface finish 表面光洁度 The most common results in what is called cold-worked steel. the most common (way): 最常见的方法 results in: 导致，引起，产生 what is called cold-worked steel: 所谓的冷作钢 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: 冷轧 Drill rod is a grade of high-carbon tool steel or high-speed steel. drill rod：钻杆 a grade of：一种 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. 光洁度 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…. 通过(用)……来识别 shop: 车间 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. 锻压成形 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: 管接头 Nodular iron is a kind of cast iron that is even better for withstanding shocks， blows， and jerks. nodular iron 球墨铸铁 Lesson 3 Gears spur (gears) and helical gears 直齿轮与斜齿轮 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 : 啮合 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：动力传动齿轮 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 ：一对啮合齿轮 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：裂开 relative to：相对于 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: 交错重叠作用 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…..倾斜 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. 在同一个坯件上切削两组相反的斜齿 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: 连续人字形 a double-helical gear: 双斜齿轮 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. 最常用的角度为90· worm and worm gears 蜗杆蜗轮 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. 为了使交叉轴斜齿轮获得线接触和提高承载能力，可以把大齿轮作成部分绕小齿轮弯曲，就象螺母套在螺杆上一样. The result would be a cylindrical worm and gear. 结果就形成一个柱形蜗杆和蜗轮 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 一对大速比齿轮 They are usually less efficient than parallel-shaft gears， however， because of an additional sliding movement along the teeth. an additional sliding movement 附加滑动 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 单头蜗杆 multiple-thread worm 多头蜗杆 lead angle 导角 For transmitting rotary motion and torque around corners， bevel gears are commonly used. ….transmitting rotary motion and torque around corners … 传递旋转运动以及绕着一个角度传递扭距…. The connected shafts， whose axes would intersect if extended， are usually but not necessarily at right angles to one another. axis (单数) ， axes (复数) 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. 一种材料与另一种材料的区别经常可以通过其物理性能，如……. 一种材料经常可以通过其物理性能与另一种材料区别开来， 如….. 热膨胀系数，导热性和导电性 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…..时候 ………….在为某些特定用途选择材料的时候…….. 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. 描述材料如何对机械使用起反应的 那些性能对…..更重要. 在选择与设计有关的材料时，…. These mechanical properties relate to how the material will react to the various loading during service. 材料在使用中(如何)对各种载荷的反应 relate to: 与….有关 Mechanical properties are the characteristic responses of a material to applied forces. responses of A to B ----- A respond to B A对B的反应 applied forces 外力 the characteristic responses 特性的反应 These properties fall into five broad categories: strength， hardness， elasticity， ductility， and toughness. fall into : 变 (分) 成; 分解 five broad ( main， major )categories : 五大类 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：磨损 mate or mesh : 啮合 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 专业英语翻译理论 2. 1 翻译的定义 语言是人类交流思想的一种手段，使用不同语言的人们要交流思想， 必须借助翻译。 所谓“翻译”就是一种语言文字的思想内容和风格用另一种语言的习惯表达方式确切而完整地重新表达出来的过程。 2. 2 翻译的本质 语言实际上就是一种语码，英语名叫code。Code 这个词既可以是明码，也可以是密码。人们用语言进行交流的过程，就是“用（Encode）和“解码”(Decode) 的过程。所谓“用码”就是人们把自己想描述的客观事实，想要的表达的思想情感，转换成语码，即用语码来表达。所谓“解码”，就是用语言表达出来的信息，理解后还原成所表达的客观事物或思想情感。所以，翻译的本质就是一个对原语的密码进行破译，也即“解码”，对译语用明码进行表达，即“用码”的语言活动。 2. 3 翻译的标准 翻译的标准既是衡量译文质量的尺度，也是指导翻译实践的准则，因此翻译的标准一直是翻译工作者关注的问题，其中最有影响的是清末著名的翻译家严复先生在1898年提出的“信、达、雅三原则。由于这个提法严谨准确，历来为后人所推崇，至今仍有很大影响。只是随着时代的发展，人们对翻译标准的认识，已有了一些进一步的见解。就科技英语的翻译而言，人们更趋向于刘重德教授提出的“信、达、切”标准。 2. 4 翻译的基本方式及其选择 2.4.1翻译的基本方式 翻译的基本方式有直译，意译，音译，阐译四种． 1. 直译 所谓直译，就是既忠实于原文的内容，又忠实于原文的形式的翻译方式．英汉两种语言，其句子的主干成份的语序在基本句型中是一致的．这便为直译这种翻译的基本方式奠定了基础．如英语中的：Two plus two equals four.　 译成汉语便是： 二加二等于四． 可以看出，在上述句型中，两种语言的语序是完全一致的．因此，可以用直译的方式． 直译是最为重要的方式，也是所有翻译方式的基础。但应该指出的是，直译并不等于死译，不能望文生义。 如前所述，直译能保证或基本保证与原文在形式上的一致，从而具有更忠实于原文的效果。所以翻译时首选直译。 意译 所谓意译，就是只忠实于原文的内容，不拘泥于原文的形式的一种翻译方式。也就是说，当译文与原文在神似与形似不能统一时，只得重神似而不重形似了，这便是意译。试以下述两句为例。 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. 尽管一篇译文犹如新瓶装旧酒或是女扮男装，但它们的效果仍旧可 以甘醇香甜和楚楚动人 b. A translation may preserve old content in new form with all its taste and liveliness. 一篇译文可以以新形式传达原文的内容，并保持原文的色彩和风姿。 上述两句深层语义相通但表层结构的简繁，选词的色彩却相去甚远。如果把 b句的译文作为 a 句的译文，这在翻译上就称之为意译。 应当指出：采用意译方式时，应注意的是一定要以神似为原则，不能意译过头。意译不等于自由翻译。意译过头，就是翻译上的自由主义。 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：传动轴 the machine member， the mechanical element: 机械构件，机械零件 support: 支持， 支撑 basic functions of rotation: 基本的旋转功能 传动轴是支撑滚轮和轮子机械零件以便它们能够完成基本的转动功能 传动轴是支撑滚轮和轮子使它们能够完成基本转动功能的机械零件。 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 各种各样的 round metal bars 金属棒 machine n. 机床 v. 加工 dimension n. 尺寸 v. 标尺寸，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：应力与应变 machine parts：机器零件 Standardized procedures have been evolved for determining the material characteristics and size requirements for safe and economical construction and operation. standardized procedures 标准化的步骤 evolve: 改进 safe and economical construction and operation 结构和操作的安全性 和经济性 Most shafting is rigid and carries bending loads without appreciable deflection. rigid：adj. 刚性的 rigidity n. bending loads 弯曲载荷 deflection 挠度 Some shafting is highly flexible. It is used to transmit motion around corners. flexible：柔性 motion around corners 绕着角度运动 solid shafting 实心轴 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 : 专门的轧制工序 extremely large shafts：特大轴 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：轴肩 position ：位置 定位 the rotor assembly ：转子装配 hollow shafting， solid shafting To minimize weights， solid shafting is bored out or drilled， or hollow pipes and tubing are used. bore: 镗孔 drill: 钻孔 pipe：空心管 tubing：管材 Hollow shafts also allow internal support or permit other shafting to operate through the interior. internal support : 内部支撑 interior ：内部（侧），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 ：空气压缩机 gas turbine：燃气蜗轮 jet aircraft engine：喷气式飞机发动机 internal speed reduction shaft：内部减速轴 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 不定式短语表示目的 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：目测 forging cracks：锻造裂缝 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 刚性联轴器 flexible couplings 柔性联轴器 A coupling is a device for connecting the ends of adjacent shafts. adjacent shafts：相邻的轴 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：意义 worn parts：磨损件 a flanged rigid coupling：法兰盘刚性联轴器 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：直线或角度偏差 A flange is keyed to each of the connection shafts; then a series of through bolts is used to connect the flanges. key：n.键 vt. 用键连接（定位） through bolts 贯穿螺栓，穿钉 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：紧固件 a potential safely hazard：隐患 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：螺栓分布圆 allowable stress：许用应力 the sleeve coupling 套筒联轴器 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（定语从句)精确地控制(确定) holding power: 夹持力 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: 零件的制造与安装 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 轴的逆向扭曲 Flexible couplings can eliminate some of these problems， provided the amount of misalignment is not too great. provided (that) + 从句; providing (that) + 从句 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: 十字联轴器 The end sections are rigidly attached to the shafts. Be attached to: 与…..相连 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: 中间的链接部分 engage: 配合; 啮合 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: 烧结粉末金属 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. 增译法 1. 英语复数名词的增译： 复数名词前可增加适当的表示复数概念的词，如“一些”、“许多”、“一批”、“各种”等词，使其复数意义更加明确。例如：（1）After a series of experiments important phenomena have been ascertained. 经一系列实验后，查明了_______ 重要现象。 2. 英语中表示动作意义名词的增译： 在翻译英语文献时，常须根据上下文的意义来补充一些表示动作意义的名词，如“作用”、“现象”、“效应”、“方法”、“过程”等等。例如： Oxidation will make iron and steel rusty. 氧化_______ 会使钢铁生锈。 3 添加概括性的词引起的增译： 在句中列举几种情况时，可根据并列成分数量的多少，增译数、量词表示概括。例如： The factors， voltage， current and resistance， are related to each other. 电压、电流和电阻这_______ 因素是相互关联的。 4. 添加语气连贯性词引起的增译： 为了使译文的上下文措词连贯，也就是使译文表达通顺，使词与词、句与句之间前后连贯，有时要增译语气连贯性的词，使前后语气加强联系，主要是连词、介词和副词。 例如： Many persons learned to program with little understanding of computers and their applications. ________许多人对计算机及其应用没有多少了解______却学会了编程序。 5. 被动语态引起的增译 英汉翻译中，有时会将被动语态译成主动语态。这时原文中没有出现的行为主体便会在译文中出现，因而也就引起增译。例如： Rubber is found a good material for the insulation of cable. ________发现橡胶是一种用于电缆绝缘的理想材料。 The mechanical energy can be changed back into electrical energy by means of a generator. 利用发电， _______ 机械能转换成电能. Lesson 5 Bearings A bearing can be defined as a member specifically designed to support moving machine components. moving machine components 运动着的机器零件 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 曲轴轴承 the automotive engine 汽车引擎 electric motors 电机 Since there is always relative motion between a bearing and its mating surface， friction is involved. relative motion 相对运动 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 滑轮， 刹车和离合器 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 导致， 引起 result from 由于 Journal and antifriction bearings are the two general types of bearings in existence. Journal and antifriction bearings 轴颈轴承和减摩轴承 in existence 现有的， 存在的， 现存的 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 运动阻滞效应 rolling resistance 滚动阻力 rolling friction 滚动摩檫 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，会合)， 连同…..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….考虑进去 bearing pressures 承受的压力 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 圆柱形轴瓦 containing properly machined inside and outside diameters 包含适当加工的内径和外径 The journal is usually the part of a shaft or pin that rotates inside the bearing. journal：轴径 the part of a shaft or pin：那部分轴或销 Fig 5-1 shows such a bearing， which is also commonly called a sleeve bearing. a sleeve bearing：套筒轴承 Notice the oil hole that leads to an axial oil groove. lead to: 通向 an axial oil groove：轴向油槽 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. 镗孔 n. 内径 The bearing outside diameter is supported in a properly machined bore of a fixed housing. a properly machined bore of a fixed housing: 适当加工的内孔 固定的壳体 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: 壳体的一侧 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 轴瓦内径向下磨损 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 轴向载荷 radial loads 径向载荷 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: 利用滚动体来工作 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 腐蚀 dirt contamination 灰尘污染 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 交变应力 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…. 来衡量 shaft revolutions: 轴的旋转 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: 统计学应考虑的事情 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 : 突出的特点 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： 防尘罩与密封圈 foreign contaminants： 外来污染物 Some antifriction bearings contain a permanently sealed lubricant which is administered by the manufacturer and lasts for the life of the bearing. 一些滚动轴承有永久密封在内的润滑剂，这些润滑剂是由制造商给予的并在轴承寿命期内连续使用。 be appropriate for ….: 对....适合 installation: 装置，设置，安装，配合 inner race: 内圈 outer race: 外圈 rub: 摩檫 ubiquitous: 普遍存在，处处都有 diverse: 各种各样的 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. 减译法 所谓减译，即把英语原文中的一些词如冠词、代词和介词等在译成汉语时可省略不译。 在下面三种情况中所省略的词语在英语中是必不可的。但译成汉语是多余的，常采用减译：英语句子中，有的词从语法结构上讲是必不可少的，但并无什么实际意义， 只是在句中起单纯的语法作用；有的词在英语中用的非常普遍，但在汉语中却很少使用甚至根本不用；有的词或成分如果照字面一一译出又显得多余、累赘，甚至会造成译文逻辑不通或修辞不当。 冠词的减译： 英语冠词是附在普通名词前的一种虚词，是使用频率最高的功能词之一，但其本身没有独立的词汇意义，只对名词起限定和辅助说明的作用。汉语中没有冠词，也没有与之相应的词类，因此在将英语译成汉语时，除少数情况外，冠词一般都应减去不译。例如： A liquid metal becomes a gas at or above its boiling point. 在沸点或沸点以上，金属液会变成气体。 但有两种情况例外：当不定冠词具有明显的数字概念或与单数可数名词连用，表示单位数量时，一般必须译出。例如： Double ladling is an old method and used only to a limited extent. 双包法是一种古老的方法，它仅在一个有限的范围内使用 （2）定冠词在起着特指某具体事物的作用时，通常也必须译出。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. 这两个表面互相“湿润”的容易程度，初始炉料的化学成分以及温度，将决定碳在铁中的溶解度。介词的减译： 英语介词丰富，使用频繁。它通过用来表示名词或代词等和句中其他词之间的关系。汉语中也有介词，但数量有限，使用也不多，词与词之间的关系主要是通过词序和意会来区分。因此在英译汉时，介词除了转译为汉语等词类外，减译的情况较多。例如： It is necessary to develop our computer science at high speed. 必须高速发展我国的计算机科学。 What is the different between a mixture and a compound? 混合物与化合物的区别何在？连词的减译： 英语在句法构造上采用形合法，所以连词在英语中使用频率较高。汉语的句法构造主要采用意合法，故连词用得较少。多数汉语句子是按时间顺序和逻辑关系排列的，语序固定，各成分之间 的关系较清楚，因此在英译汉时，往往可以，有时甚至必须将英语中的某些连词减译。例如： These metals usually require a certain amount of preheating before welding and then allowed to cool slowly after the weld is completed. 这些金属通常要求在焊接前进行一定的预热，在焊接完成后缓慢冷却 （2）Give him an inch， and he will take a mile. 他得寸进尺。代词的减译：人称代词的减译：在一段文字中，如果紧连的两个句子主语相同，汉语习惯其中一句可以不用主语。而英语则每句必有主语，常在后一句中用人称代词表示和前句相同的主语这样使用的英语人称代词则减译。例如： When carbon burns it unites with oxygen from the air. 碳燃烧时与空气中的氧结合。 人称代词中的we和you，在专业文章中往往是泛指，具有“概括”或“不定”的意义，翻译时大多不需译出。 Before you begin to work the instrument， first read the instruction carefully. 在开始使用本仪器前，请首先仔细阅读说明书。 Given the weight and the specific gravity of a body， we can calculate its volume. 给出物体的重量和密度，就能求出其体积。物主代词的减译： 英语中的物主代词一般不能省略。而汉语中在关系已经明确的情况下不必再用物主代词来明确所属关系。因此汉译时减译英语物主代词的情况十分常见。例如： Ventilation is one way of reducing emissions in the workshop， however， you cannot depend on this alone to solve your dust problem. 反身代词的减译 根据汉语的习惯，某些作宾语或同位语的反身代词往往是可以减译的。不定代词、连接代词也常可减译。例如： Like zinc， iron also converts itself into a vapor at high temperature. 像锌一样，铁在高温下也会变成蒸汽。（反身代词itself减译） 同义词或近义词的减译： 在专业英语著作中，常有两个同义词连用的现象，即对同一概念用两个词重复表达。这两个词中前一个往往是专业词汇，后一个往往是普通词汇。两者在语法上是同位关系，常可用连词“or”连接。作者这样做往往是出于强调或为了适应不同层次读者的需要。但在译成汉语时，为了使概念准确，避免文字重复或含糊不清，只需要译出其中一个汉语中通用的名称就可以了。例如： The force of gravity acts vertically downwards and gives an object “weight or heaviness”. 重力垂直向下作用，使物体具有“重量”。（weight和heaviness重复，减译） 上面介绍了减词译法常见的一些情况，可见其应用十分广泛。减译的目的是为了使译文简洁明快、严谨精炼，即达到所谓“削枝强干”。 减译后的译文虽然在词量上和原文不尽一致，但在意思和精神上都应该和原文一样是绝对完整的，即所谓“减词不减意”。在使用减词法时值得注意的是，在减译中决不能更改或漏译原文的内容，更不能“滥砍滥伐”，借减译之名随意删去难懂难译的词句。 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，独特地，典型地 通常地 2. specify: 规（指，给，确）定 3. nominal dimension: 公称尺寸 In reality， components cannot be made repeatedly to nominal dimensions， due to surface irregularities and the intrinsic surface roughness. in reality: in fact 实际上 Some variability in dimensions must be allowed to ensure manufacture is possible. variability：变化 However， the variability permitted must not be so great that the performance of the assembled parts is impaired. the performance of the assembled parts：装配件的工作性能 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: 适用于 2. the acceptable range of component dimensions: 3. process: 过程，处理，加工 For example， the power produced by a given type of internal combustion engine varies from one engine to another. internal combustion engine：内燃机 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: 频率分配曲线 2. the normal distribution( the Gaussian distribution)：正态分布（高斯分布）译：实际上，我们常常发现这种变化模型是频率分配曲线…… 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: 互换性 Tolerances are specified on critical dimensions that affect clearances and interference fits. 1. critical dimensions: 关键尺寸 2. clearances and interference fits: 间隙与过盈配合 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(标)出，表明， 确(指，规)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: 双向公差 For a unilateral tolerance， one tolerance is zero， e.g.40.000 +0.006. a unilateral tolerance: 单向公差 Most organizations have general tolerances that apply to dimensions when an explicit dimension is not specified on a drawing. 1. organizations: 机构，组织 2. general tolerances: 通用公差 3. explicit : 明白(显，确，晰)的，清楚的 explicit function 显函数 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: 冲孔 When specifying a tolerance for a component， reference can be made to previous drawings or general engineering practice. 1. make a reference to :参考….. 2. general engineering practice: 一般工程惯例 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 : 向导，指南，入门 2. the general applications of tolerances: 一般公差应用 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: 一组数值 2. a corresponding chart: 对应的图表 3. the size of component under consideration: 正在考虑的零件尺寸 The section following gives specific examples of this for a shaft or cylindrical spigot fitting into a hole. 1. specific examples : 具体例子 2. cylindrical spigot: 柱形销 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: 换句话说，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: 变化，种类，品种 Size: a number expressing in a particular unit the numerical value of a dimension. a particular unit: 专用单位 Actual size: the size of a part as obtained by measurement. Limits of size: the maximum and minimum sizes permitted for a feature. feature: 特点，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: 参考(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: 按照惯例 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 ：圆锥的 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，顶尖 v. 定中心，找中心，打中心孔 2. faceplate：面板，花盘 3. a jaw chuck： 带爪卡盘 4. a draw-in chuck: 内拉卡盘 5. collet: 筒夹 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 :外圆加工 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:简单的，清楚的，普通的，平滑的， Work held in this manner can likewise be centered， drilled， bored， or reamed. likewise: adv 同样，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: 螺纹 3. attachments :辅助装置 4. milling:铣削 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: 机床 The engine lathe is the basic turning machine from which other turning machines have been developed. engine lathe: 普通车床 turning machines， lathe : 车床 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: 皮带 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 : 坚固的， 结实的 heavy-duty : 重型的 drive plate: 驱动盘 impart …. to : 把…给予 ; 把….传给 positive motion : 确动 The drive plate may be fastened to the spindle by threads， by a cam lock mechanism， or by a threaded collar and key. thread : 螺纹 a cam lock mechanism : 凸轮锁定机构 a threaded collar and key : 螺纹凸缘与键 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: 刀具夹紧装置 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: 安装，调整 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 ：从….观点来看; 在….方面 (意义) (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: 横拖板 The work is fed through the machine spindle into the chuck， and the tools are operated automatically by cams. chuck: 卡盘 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: 证明…..是正当(正确，合理)的; 认为…..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 : 生产 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 : 夹具，夹持器，保持架，支架 feed ：v. 喂食，进给 n. 进给量 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 : 单刃 multipoint : 多刃 random ：任意的，随机的，不规则的 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 车床 turret lathes 转塔车床 tracing and duplicating lathes 仿形车床 shapers and planers 牛头刨床与龙门刨床 boring machines 镗床 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： 锯床 Machines using random-point cutting tools include: (1) cylindrical grinder， (2) centreless grinders， (3) surface grinders. cylindrical grinder：外圆磨床 centreless grinders： 无心磨床 surface grinders：平面磨床 Special metal removal methods include: (1) chemical milling， (2) electrical discharge machining， (3) ultrasonic machining. chemical milling ：化学蚀刻 electrical discharge machining：放电加工 ultrasonic machining：超声波加工Sex红软基地

机械工程材料ppt作品：这是机械工程材料ppt作品，包括了绪论，工程材料的力学性能，金属材料的基础知识，金属的塑性变形与再结晶，钢的热处理，金属材料，非金属材料，机械零件的失效与选材，新材料和新工艺等内容，欢迎点击下载。

机械工程测试技术ppt：这是机械工程测试技术ppt，包括了绪论，信息信号，测量误差的分类，测试装置的基本特性，常用传感器与敏感元件，信号调理与记录，振动的测试等内容，欢迎点击下载。

机械工程材料论文PPT课件：这是一个关于机械工程材料论文PPT课件，主要介绍了金属材料的主要性能、金属和合金的晶体结构与结晶、铁碳合金、常用金属材料、其他工程材料、机械零件选材的一般原则等内容。第二章 机械工程材料基础第一节 金属材料的主要性能第二节 金属和合金的晶体结构与结晶第三节 铁碳合金第四节 常用金属材料第五节 其他工程材料第六节 机械零件选材的一般原则 拉伸试验 1. 屈服点——材料产生屈服点的最小应力。 表征金属发生明显塑性变形的抗力。2. 抗拉强度——材料在拉断前所承受的最大应力。表示材料抵抗均匀塑性变形的最大能力。（三）硬度 ——指工程材料抵抗更硬的物体压入其表面内的能力，表示材料抵抗局部塑性变形或破坏的性能，是一个综合反映材料弹性、塑性、强度和韧性的机械性能指标。70~85HRA 25~100HRB 20~70HRC 一、金属的晶体结构（一）晶体 特点：1. 具有规则的外形；2. 具有固定的熔点；3. 具有各向异性。（二）晶格 ——描述原子在晶体中规则排列方式的空间几何图形，欢迎点击下载机械工程材料论文PPT课件哦。