机械制造专业英语(章跃版)课后句子翻译答案

英语课后重点短语LESSON 1(P15)1)the fundamental concept 基本概念2)cross section 横截面3)the internal stresses produced in the bar 棒内应力4)continuous distribution of bydrostatic pressure 净水压力的连续分布5)the tensile load 拉伸载荷6) a uniform distribution over the cross section 横截面上的均匀分布7)arbitrary cross-sectional shape 任意横截面形状8)tensile stress 拉应力9)compressive stresses 压应力10)a normal stress 正应力11)through the centroid of the cross sectional area 通过质心的横截面积12)the uniform stress condition 均应力状态13)the stress distribution at the end of the bar14)high localized stresses 局部高应力15)an axially loaded bar 轴向加载杆16)a tensile strain 拉伸应变17)an elongation or stretching of the material 延长或拉伸的材料18)a compressive strain 压应变19)the ratio of two lengths20)purely statical and geometrical considerations 从纯静态和几何关系考虑LESSON 2(P25)1)the main manifestations of capacity 功能的主要表现形式2)the maximum unit load(stress) 最大单位载荷3)stress-strain diagram 应力-应变图4)the simple tensile test 简单拉伸试验5)the percentage elongation at rupture 断裂延伸率6)the end of tensile specimens 拉伸试样的末端7)permanent deformation 永久变形8)the resulting load-displacement curve 所产生的载荷-位移曲线9) a substsntial yielding of the material 大量高产的物质10)yield point 屈服点11)the trainsition from elastic to plastic behavior12)material property table 材料性能表13)plastic defomation 塑性变形14)a specified standard length of the specimen 指定的标准试样的长度15)at the moment of rupture 在破裂时16)short cylindrical specimens 短圆柱试样17)ductile materials 任性材料18)high stress concentration 高应力集中19)ultimate tensile strength 极限抗拉强度20)strain hardening zone 应变硬化区LESSON 3(P37)1)circular cross section 圆截面2)the position of mountings 安装位置3)nominal size 标准尺寸4)length of shaft subjected to twist 轴的受扭长度5)minimize stress concentration 尽量减小应力集中6)from the standpoint of stress 从应力角度7)equations for a shaft in pure torsion 轴纯扭转的方程式8)diameter of solid shaft 实心轴的直径9)outside diameter of hollow shaft 空心轴的外径10)the amount of twist in a shaft 轴的扭转量11)torsional deflection 扭转变形12)shear modulus of elasticity 剪切弹性模量13)be closer to the vertical load 接近于垂直载荷14)the endurance limit 疲劳极限15)the allowable shearing stress 许用剪切应力16)equation for equivalent moments 方程的等效力矩17)the design stress values for flexure 设计弯曲应力值18)the angle of twist 扭转角19)antifricton bearings 滚动轴承20)the amount of twist in a shaft 轴的扭转量LESSOM 4(P51)1)herringbone gears 人字齿轮2)spiral gears 螺旋齿轮3)worn gears 蜗轮4)bevel gears 圆锥齿轮5)hypoid gears 准双曲面齿轮6)sizes of spur-gear teeth 齿轮轮齿的尺寸7)the automotive rear axle drives 汽车后桥驱动8)rack-and-pinion drives 齿条和小齿轮驱动器9)diametral pitch 径节10)pitch circle 节圆11)the tangency point 切点12)pressure angles 压力角13)an involute curve 渐开线14)the radial distant 径向距离15)at right angles 成直角16)the average number of teeth in contact17)the reciprocal of the diametral pitch 对等径节18)to change inches to millimeters 把英寸换算成毫米19)a line perpendicular to the centerlines 垂直中心线的直线20)center distance between two meshed gears 两个齿轮的中心距LESSION 5(P62)1)plate cams 盘形凸轮2)cylindrical cams 圆柱凸轮3)the cam assembles in automatic record players 汽车发动机上的凸轮组件4)cam profiles 凸轮轮廓5)make a full-scale template 制造一个实体样板6)in the course of several revolutions of the cam 在凸轮中转几圈7) a tangential plate cam 切向盘形凸轮8) a translation cam 移动凸轮9)the groove in the periphery of the cam 凸轮表面的槽10)a guided vertical reciprocated follower 做垂直运动的往复件11)a constant-diameter cam 等径凸轮12)automatic washing machines13)a face cam 面凸轮14)the edge of a pivoted follow 摆动从动件的边缘15)a reciprocating knife-edged follower 作往复运动的刀口式从动件16)miniature snap-action electrical switchies 小的速动开关17)a pivoted flat-faced follower 安装在摆臂上的滚子从动件18)air pilot values19)the abrupt change in cam profile 在凸轮轮廓上的突变20)a Scotch yoke mechanism 苏格兰的克机构LESSION 6(P73)1)developing and demanding industry 一个处在发展中社会需要的产业2)propeller shaft 传动轴3)suspension components4) a sliding splined type of joint 滑动花键连接5)two rear axle shafts 两个后半轴6)to mesh with a larger bevel gear 与更大的锥齿轮啮合7)the universal joint 万向节8) a steering wheel 转向轮9)unevenness of road surfaces 路面的不平度10)the transverse line of the axle shafts 后横半轴11)to cause excessive tyre wear 造成轮胎的过度磨损12)the exactly similar diameter 直径非常接近13)quarter-elliptic leaf springs 四分之一随圆形钢板板式弹簧14)the transmission of shock 冲击15)road surface variation 路面变化16)the final-drive gears 最终传动齿轮副17)the precise alignment of shaft 精确同轴18)a rotating drum 转动筒鼓19)a hand lever 手刹杆20)be locked in the one position 被固定某一位置LESSION 8(P99)1)bulk deformation of metals 金属的变形2)forging，rolling or extruding 锻造滚压挤压3)plastic deformation 塑性变形4)impact blows 冲击5)the recrystallization point of the mental6)hot working and cold working 热加工和冷加工7)better surface finish8)hammer forging 锤锻9)striking the hot metal 锻打热金属10)a slow squeezing action 缓慢加压11)open dies and closed dies 开模和闭模12)bevel gears with traight or helical teeth 用直齿或螺旋加工锥齿轮13)impression dies 型腔模14)each of several die cavities 每一个模膛15)mass production16)a homogeneous circumferential grain fiow 均匀的周向纤维流17)the three-dimensional description 三维描述18)computer simulation 计算机仿真19)hydraulic presses 液压压力20)be rough- and finished-machined 粗加工和精加工LESSION 9(P110)1)carrying high-amperage current 携带高安培电流2)the electrode and the work-piece 电机和工件3)the weld pool 焊接熔池4) a column of ionized gas called plasma 一个列的电离气体称为等离子体5)the oxides and nitrides 氧化物和氮化物6)the positive ions 阳离子7)deleterious substances 有害物质8)the newly solidified mental 刚凝固的金属9)in overhead welding 仰焊10)current density 电流密度11)deposition rate 沉积速率12)an unbalanced magnetic field 不平横磁场13)arc blow 电弧偏吹14)the electrode coating 电极涂层15)in overhead position 在仰焊的位置16)the cooling rate of the deposited metal 沉积金属的冷却速度17)a more homogeneous microstructure 更均匀的微观结构18)a smooth flow of molten metal 顺畅熔融19)cellulosic-coated electrodes 纤维质涂层的焊条20)perpendicular to the current path 与电路垂直LESSION 10(P123)1)plain carbon steel 碳素钢2)carbon content 碳含量3)low carbon steel 低碳钢4)medium carbon steel 中碳钢5)high carbon steel 高碳钢6)be cold worked 冷加工7)be heat treated 热处理8)contain 20 point of carbon 含20%的碳9)in the hot-rolled condition 在热轧条件下10)heat-treat-hardened plain carbon steel 热处理硬化普通碳钢11)free-machining steels 易切削钢12)hot short 热脆性13)cold shortness 冷脆性14)the isothermal transformation curves 等温移动曲线15)grain refinement 细化晶粒16)stainless steel 不锈钢17)AISI steels 美国钢铁协会钢18)Iron-carbon equilibrium diagram 铁碳平衡表19)Tool and die steel 工具钢和模具钢20)High corrosion chemical resistance 高耐腐蚀和耐化学性能LESSION 11(P134)1)allotropic materials 同素异晶材料2)plain low carbon steel 普通低碳钢3)hypoeutectiod steel 亚共析钢4)normalized steel 正火钢5)hypereutectoid steel 过共析钢6)eutectoid composistion 共析钢7)grain houndaries 晶界8)ferrite matrix 铁氧体矩阵9)about 60℃about the Ac1 temperature 大约Ac1温度以上60摄氏度10)the nose of the I-T curve I-T曲线鼻共处11)cooling rate 冷却速率12)quenching shock 淬火介质13)thermal stress 热应力14)thermal shock 热冲击15)a tempered steel 回火钢16)temper brittlement 回火脆性17)in the tempering or drawing proceduce 在回火阶段18)hardened steel 硬化钢19)full annealing 充分退火20)to dissolve all the cementite 溶解渗碳体LESSION 15(P177)1)turning，facing and boring 车削，车端面和镗孔2)split nut 对开螺母3) a single setup of the workplace 工件在一次性定位安装4)headstock assembly 主轴箱组件5)tailstock assembly 尾座组件6)carriage assembly 溜板箱组件7)lead screw and feed rod 丝杠和光杆8)two sets of parallel，longitudinal ways 两组平行的导轨9)to assure accuracy of alignment 为了保证装配的精确度10)a set of transmission gears 一套传动齿轮11)the maximum size of bar stock 棒料的最大尺寸12)gear box 齿轮箱13)a V-belt or silent-chain drive V型带和无声传动装置14)carbide and ceramic tools 硬质合金和金属陶瓷刀15)the inner ways of the end 床身的内侧导轨16)tailstock quill 尾座套筒17)a graduated scale 通常情况18)in the direction normal to the axis of rotation of the work 在垂直工件旋转轴线方向19)manual movement of the carriage 托盘的手工移动20)per revolution of the spindle 主轴旋转一周LESSION 16 (P188)1) a multiple-tooth cutter 多齿铣刀2)progressive formation 逐渐成形3)in a direction perpendicular to the axis of the cutter 在垂直刀具轴线的方向4)the metal removal rate 金属切除率5)produce good surface finish 产生好的表面光洁度6)in job-shop and tool and die work7)teeth located un the periphery of the cutter body8)slab milling 板铣9)face milling 端面铣削10)up milling 逆铣11)down milling 顺铣12)the direction of feed of the workpiece 工件的进给方向13)the clamping device 夹具14)the smoothness of the generated surface 铣削表面的平整度15)the sharpness of the cutter edges 切削刃的锋利程度16)at the end of the tooth engagement17) p rofile cutters 仿形铣刀18) c arbide- and ceramic- tipped cutters 硬质合金及陶瓷-硬质合金刀具19)negative-rake-angle cutters 负倾角刀20)arbor cutters and shank cutters 乔木刀和柄刀。

应力与应变第一单元That branch of scientific analysis which motions, times and forces is called mechanicsand is made up of two parts, statics and dynamics.研究位移、时间和力运动乘力是科学分析法的一个分歧，被称作力学，力学由两大部静力学和动力学。

分组成，For example, if the force operating on a sleeve bearing becomes too high, it will squeeze outthe oil film and cause metal-to-metal contact, overheating and rapid failure of the bearing.例如：如果止推轴承上的作用力过大的话，会挤出油膜，引起金属和金属之间的相互接触，轴承将过热而迅速失效。

and of place application, direction, concept Our intuitive of force includes such ideas asmagnitude, and these are called the characteristics of a force.。

力的直观概念包括力的作用点、大小、方向，这些被称为力的三要素All bodies are either elastic or plastic and will be deformed if acted upon by forces. When thedeformation of such bodies is small, they are frequently assumed to be rigid, i.e., incapableof deformation, in order to simplify the analysis.的，如果受到力的作用就产生变形。

机械设计制造及其自动化专业英语翻译Unit 1 Metals金属Unit 2 Selection of Construction Materials工程材料的选择淬透性：指在规定条件下，决定钢材淬硬深度和硬度分布的特性。

即钢淬火时得到淬硬层深度大小的能力，它表示钢接受淬火的能力。

钢材淬透性好与差，常用淬硬层深度来表示。

淬硬层深度越大，则钢的淬透性越好。

钢的淬透性是钢材本身所固有的属性，它只取决于其本身的内部因素，而与外部因素无关。

钢的淬透性主要取决于它的化学成分，特别是含增大淬透性的合金元素及晶粒度，加热温度和保温时间等因素有关。

淬透性好的钢材，可使钢件整个截面获得均匀一致的力学性能以及可选用钢件淬火应力小的淬火剂，以减少变形和开裂。

淬透性主要取决于其临界冷却速度的大小，而临界冷却速度则主要取决于过冷奥氏体的稳定性，影响奥氏体的稳定性主要是：1.化学成分的影响碳的影响是主要的，当C％小于1.2％时，随着奥氏体中碳浓度的提高，显著降低临界冷却速度，C曲线右移，钢的淬透性增大；当C％大于时，钢的冷却速度反而升高，C曲线左移，淬透性下降。

其次是合金元素的影响，除钴外，绝大多数合金元素溶入奥氏体后，均使C曲线右移，降低临界冷却速度，从而提高钢的淬透性。

2.奥氏体晶粒大小的影响奥氏体的实际晶粒度对钢的淬透性有较大的影响，粗大的奥氏体晶粒能使C曲线右移，降低了钢的临界冷却速度。

但晶粒粗大将增大钢的变形、开裂倾向和降低韧性。

3.奥氏体均匀程度的影响在相同冷度条件下，奥氏体成分越均匀，珠光体的形核率就越低，转变的孕育期增长，C曲线右移，临界冷却速度减慢，钢的淬透性越高。

4.钢的原始组织的影响钢的原始组织的粗细和分布对奥氏体的成分将有重大影响。

5.部分元素，例如Mn，Si等元素对提高淬透性能起到一定作用，但同时也会对钢材带来其他不利的影响。

可锻性(forgeability)金属具有热塑性，在加热状态(各种金属要求温度不同)，可以进行压力加工，称为具有可锻性。

第一单元应力与应变That branch of scientific analysis which motions, times and forces is called mechanicsand is made up of two parts, statics and dynamics.研究位移、时间和力是科学分析法的一个分支，被称作力学，力学由两大部分组成，静力学和动力学。

For example, if the force operating on a sleeve bearing becomes too high, it will squeeze out the oil film and cause metal-to-metal contact, overheating and rapid failure of the bearing.例如：如果止推轴承上的作用力过大的话，会挤出油膜，引起金属和金属之间的相互接触，轴承将过热而迅速失效。

Our intuitive concept of force includes such ideas as place of application, direction, and magnitude, and these are called the characteristics of a force.力的直观概念包括力的作用点、大小、方向，这些被称为力的三要素。

All bodies are either elastic or plastic and will be deformed if acted upon by forces. When the deformation of such bodies is small, they are frequently assumed to be rigid, i.e., incapable of deformation, in order to simplify the analysis.所有的物体既可以是弹性的也可以是塑性的，如果受到力的作用就产生变形。

Lesson 1 Mechanical Properties of MetalsMechanical properties are the characteristic responses of a material to applied forces. These properties fall into five broad categories: strength, hardness, elasticity, ductility, and toughness.Strength is the ability of a metal to resist applied forces.Strength properties are commonly referred to as tensile strength, bending strength, compressive strength, torsional strength, shear strength and fatigue strength.Tensile strength is that property which resists forces acting to pull the metal apart. It is one of more important factors in the evaluation of a metal.Compressive strength is the ability of a material to resist being crushed. Compression is the opposite of tension with respect to the direction of the applied load. Most metals have high tensile strength and high compressive strength. However, brittle materials such as cast iron have high compressive strength but only a moderate tensile strength.Bending strength is that quality which resists forces from causing a member to bend or deflect in the direction in which the load is applied. Actually a bending stress is a combination of tensile and compressive stresses.Torsional strength is the ability of a metal to withstand forces that cause a member to twist.Shear strength refers to how well a member can withstand two equal forces acting in opposite directions.Fatigue strength is the property of a material to resist various kinds of rapidly alternating stresses. For example, a piston rod or an axle undergoes complete reversal of stresses from tension to compression. Bending a piece of wire back and forth until it breaks is another exampleof fatigue strength.Hardness is that property in steel which resists indentation or penetration. Hardness is usually expressed in terms of the area of an indentation made by a special ball under a standard load, or the depth of a special indenter under a specific load.Elasticity is the ability to spring back to original shape. Auto bumpers and all springs should have this quality.Ductility is the ability to undergo permanent changes of shape without rupturing. Modern, deep-formed auto bodies and fenders, and other stamped and formed products must have this property.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, rails, and similar products.New Words学习1.Mechanical 力学的，机械的2.Response 反应，响应，答复3.Broad 主要的，概括的4.Category 种类，类别……Notes1.Tensile strength is that property which resists forces actingto pull the metal apart.抗拉强度是金属抵抗外力把它拉断的能力。

CHAIN DRIVESChain drives occupy a unique position in the mechanical field.In a sense,they are similar to belt drives;a chain connects sprockets on the driving and driven shafts.The velocity ratio transmitted from one shaft to the other depends on the size of the two sprockets(at the pitch line);unlike that found with belts,the ratio is positive.In belt drive ,creep and slip play important roles and must be considered;in a chain drive,which is made up of numerous links,there is a small amount of play in the total length of the chain.This may be desirable in case of small overloads.A chain drive is similar to the open-belt type of dirve in that the driving and driven shafts rotate in the same direction.There are also similarities between chain drives and gear drives.Both types transmit a positive velocity ratio.In a regular spur-gear drive,the driving and driven shafts turn in opposite directions unless an idler is employed.In gear drives employing an annular or ring gear,however,the input and output shafts rotate in the same direction.In a spur-gear drive there is very little contact between meshing gears;therefore,tooth loads are excessive.Since the connection between a chain and its sprocket extends over several teeth,no one tooth is subjected to heavy loads.Chain drives are often noisy.The silent chain type of drive was developed to counteract this undesirable characteristic.Belt,chain,and gear drives are all dangerous.Belt and chain speeds are high,as is the pitch-line velocity of most gear drives.All should be adequately covered by suitable guards(or completely enclosed) so that no boby or clothing parts can possibly be caught in the moving components.Other comparisons can be made among chain,belt,and gear drives.Gear drives can operate at higher speeds than the others,and are usually more compact.However,chain drives do not require the mounting precision that is so essential for gearing.An advantage of chain drives in comparison to belt drives is that the former do not require tension on the slack side;this leads to better bearing life.In general,chain drives are more compact than the belt type;for a given ratio,the sprockets can be smaller than belt pulleys.For a given load,chain widths are narrower than comparable flat belts.The connecting link on chain drives makes them easy to install—the chain is merely placed over the sprockets and the proper pins are placed in position.In most belt installations,force is needed to place the belt in the proper position;such action is detrimental to mounting bearings.The angle of contact for the driving sprocket can be smaller than the driving pulley for a belt drive.For a chain drive,this angle can be as small as 120 degrees.The center distance can also be small;if a 120-degree angle of contact is provided,the center distance need be no more than just enough to provide clearance for the sprocket teeth.An essential part of any chain drive is the sprocket.A chain drive requires a sprocket on the driving shaft and another on the driven shaft.Chain drives sometimes contain additional sprockets,used for additional power take-offs or for taking up chain slack.When used to take up chain slack,they are known as idlers.Idlers should be mounted on the slack side,not on the tight side.It is desirable to have an adjustment for idler positioning where possible.Fig.4-5 showsa roller-chain sprocket.Sprocket teeth are standardized to accommodate the roller chain.Various sizes of sprockets may be used,and several types are available.The simplest type is one without a hub.Sprockets are also available with hubs on one side or on both sides.Special arrangements are also possible.Certain of these are used in conjunction with a shear-pin hub;the shear pin is designed to fail in case of an accidental or unexpected overload.Some types can be installed on large lineshafts;these sprockets are made in two parts so that they can be installed without disconnecting the long length of shafting.Smaller sprockets are usually made solid;large ones are sometimes constructed with arms or spokes to reduce weight.In general,the selection of a sprocket depends on the type of application.链传动链传动在机械领域中占据了独特的地位。

Lesson 2 Hardening and TemperingPlain carbon steel has been valued from early time because of certain properties. This soft silver-gray metal could be converted into a superhard substance that would cut glass and many other substances, including itself when soft. Furthermore, its hardness could be controlled. This converting of carbon steel into a steel of useful hardness is done with different heat treatments, two of the most important of which are hardening and tempering (drawing), which you will investigate in this lesson.Hardening by quenchingAs steel is heated above the lower critical temperature of 1330F (721C), the carbon that was in the form of layers of iron carbide in pearlite begins to dissolve in the iron and form a solid solution called austenite. When this solution of iron and carbon is suddenly cooled or quenched, a new microstructure is formed. This is called martensite. Martensite is very hard and brittle, having a much higher tensile strength than the steel with a pearlite microstructure. It is quite unstable, however, and must be tempered (drawn) to relieve internal stresses in order to have the ductility and toughness needed to be useful. AISI-C1095, commonly known as water-hardening tool (W1) steel, will begin to show hardness when quenched from a temperature just over 1330F (721C) but will not harden at all if quenched from a temperature lower than 1330F (721C). This steel will become as hard as it can get when heated to 1450F (788C) and quenched in water. This quenching temperature changes as the carbon content changes. It should be 50F (28C) above the upper critical temperature for carbon steels containing less than 0.83 percent carbon. The reason carbon steel ,less than eutectoid, should be heated above theupper critical temperature is that the ferrite is not all transformed into austenite below this point, and when quenched, is retained in the martensitic structure. The retained ferrite causes brittleness even after tempering.Low carbon steels such as AISI 1020 will not, for all practical purpose, harden when they are heated and quenched. Oil- and air-hardening steels have a higher hardenability and do not have to be quenched as rapidly as plain carbon steels. Consequently, they are deeper hardening than water hardening types, which must be cooled to 200F within 1 or 2 seconds. Plain carbon steels containing 0.83 percent carbon can get as hard (RC67) as any plain carbon steel containing more carbon.TemperingTempering, or drawing, is a process of reheating a steel part that has been previously hardened to transform some of the hard martensite into softer structures. The higher the tempering temperature used, the more martensite is transformed, and the softer and tougher (less brittle) the piece becomes. Therefore, tempering temperatures are specified according to the strength and ductility desired. Mechanical properties charts, which may be found in steel manufacturers’handbooks and catalogs, give these data for each type of alloy steel.A part can be tempered in a furnace or oven by bringing it to the required temperature and holding it there for a length of time, then cooling it in air or water. Some tool steels should be cooled rapidly after tempering to avoid temper brittleness.Tempering should be done as soon as possible after hardening. The part should not be allowed to cool completely, since untempered it contains very high internal stresses and tends to split or crack. Tempering will relieve the internal stresses. A hardened part left overnight without tempering may develop cracks by itself.New words 学习1.hardening 淬火2.temper 回火3.convert 转变4.value 重视，尊重……Notes1. This soft silver-gray metal could be converted into a superhard substance that would cut glass and many other substances, including itself when soft.这种银灰色的软金属能够转变成一种超硬的物质，该物质可以切削玻璃和许多其它物质，包括处于软状态时的该金属本身。

第一单元应力与应变‎That branc‎h of scien‎t ific‎analy‎s is which‎motio‎n s, times‎and force‎s is calle‎d mecha‎n ics and is mad e up of two parts‎, stati‎c s and dynam‎i cs.研究位移、时间和力运‎动乘力是科‎学分析法的‎一个分歧，被称作力学‎，力学由两大‎部分组成，静力学和动‎力学。

For examp‎le, if the force‎ opera‎t ing on a sleev‎e beari‎n g becom‎e s too high, it will squee‎ze out the oil film and cause‎ metal‎-to-metal‎ conta‎c t, overh‎e atin‎g and rapid‎ failu‎r e of the beari‎ng. 例如：如果止推轴‎承上的作用‎力过大的话‎，会挤出油膜‎，引起金属和‎金属之间的‎相互接触，轴承将过热‎而迅速失效‎。

Our intui‎t ive conce‎p t of force‎inclu‎d es such ideas‎as place‎of appli‎c atio‎n, direc‎t ion, and magni‎t ud e, and these‎are calle‎d the chara‎c teri‎s tics‎of a force‎.力的直观概‎念包括力的‎作用点、大小、方向，这些被称为‎力的三要素‎。

All bodie‎s are eithe‎r elast‎ic or plast‎ic and will be defor‎med if acted‎ upon by force‎s. When the defor‎m atio‎n of such bodie‎s is small‎, they are frequ‎e ntly‎ assum‎e d to be rigid ‎, i.e., incap‎able of defor‎m atio‎n, in order‎t o simpl‎ify the analy‎sis. 所有的物体‎既可以是弹‎性的也可以‎是塑性的，如果受到力‎的作用就产‎生变形。

Lesson 3 Plain Carbon SteelIn simple terms, a plain carbon steel may be said to be an alloy of iron and carbon containing less than 1.7% carbon. In practice, however, these steels rarely contain more than about 1.4% carbon and other elements are also present, either as deliberate additions or as impurities.Plain carbon steels may be classified into three main groups:1.Low carbon steel (mild steel) containing less than 0.3% carbon.2.Medium carbon steel containing 0.3% to 0.6% carbon.3.High carbon steel containing 0.6% to 1.4% carbon.Low Carbon SteelsLow carbon steels may be sub-divided into:1 Dead mild steel containing 0.05% to 0.10% carbonIn the manufacture of this material, complete deoxidation is not carried out and it is made as rimming steel. It is produced as hot and cold worked sheet, strip, rod, wire and tube, and is available in the hot-worked or process annealed condition. The steel has excellent ductility, which is essential for the deep drawing of sheet, but the strength is low. This type of steel is used for the manufacture of motorcar bodies, refrigerators, washing machines, office furniture, pressings, rivets and nails.2 Carburising steels containing 0.1% to 0.2% carbonThe strength and hardness of these steels is low, but a hard surface can be obtained by carburising in order to combine a wear-resistant surface with tough core properties. The ductility makes rapid machining difficult unless the MnS content is increased by using a shlphur content of 0.2% to 0.3% with about 1% manganese.3 Constuctional mild steels containing 0.2% to 0.3% carbonAs the carbon content is raised above 0.2%, the strength increasesinto the range required for constructional purposes, but the ductility decreases. The fabrication qualities of this material are very good. The steel is hot-rolled into plate for making boilers, ships and vehicles, and also into sections for use in bridges and buildings. The steel is often used in the hot-rolled condition, but the smaller sized material may be normalized.It has been estimated that about 90% (by weight) of all steel used is of this low carbon classification.Medium Carbon SteelsMedium carbon steels are often quenched-hardened and fully tempered to give good strength with maximum toughness, which are the properties required of components such as shafts, gears and connecting rods. Steels containing 0.4% to 0.5% carbon may also be surface hardened by localized heating and quenching.High Carbon SteelsHigh carbon steels are quench hardened and lightly tempered to give high hardness with only limited toughness. Material in this classification is mainly used for making fairly small, relatively inexpensive cutting tools so that the group as a whole is known as carbon tool steel. Steels containing 0.6% to 0.8% carbon are used for making dies, springs, wire ropes and railway tyres. Many different kind of tools are made from higher carbon steels as indicated below.Limitations of Plain Carbon SteelsPlain carbon steels have many limitations including the following:a)If reasonable toughness and ductility are required, themaximum tensile strengthobtainable is about 700 N/mm2.b)Large sections cannot be effectively hardened, thusrestricting their use to relatively thin sections.c)Water quenching is necessary for full hardening withconsequent risk of distortion and cracking.d)Rapid softening above about 300 o C limits their use forhigh-speed metal cutting.e)Poor resistance to corrosion and to oxidation at elevatedtemperatures.To overcome these limitations, additional elements are added to the steel to give alloy steels with specific properties. The main alloying elements include manganese, nickel, chromium, molybdenum, tungsten, vanadium, cobalt and silicon.New words学习1.deliberate 故意的2.managanese 锰3.impurity 杂质，夹杂物4.sulphur 硫……Notes1.Ii is produced as hot and cold worked sheet, strip, rod, wireand tube, and is available in the hot-worked or process annealed condition.这种钢被制造成冷轧或热轧的钢板、棒材、带材、线材和管材，适宜在热加工状态或退火状态下使用。

一词汇a 英译汉Dimension 尺寸Machine tool Adhesiveness Compound rest复合刀具台机床粘性Apron 挡板，Climb-cut Peripheral milling Slab milling阔面铣削同向铣削Centerless grinding无心轮磨Machinery Cylindrical hole Snag 障碍机械圆柱孔Coarseness 粗糙度Up-milling逆铣Abrasive belt磨带Profile Machine table剖面机表Rectilinear Protecctive guards 直线防护String milling连续铣削b 汉译英刚度，硬度hardess 圆柱形端铣刀cylindric end mill 进给速度feed speed 托架bracket软刚，低碳钢mild steel沉头螺钉sunk screw螺线spiral 平面磨surface grind镗床boring machine 摩擦离合器friction clutch多刃刀具multipoint tool 牛头刨床shaping machine被动皮带轮Passive pulley润滑油lubricating oil燕尾槽dovetail groove 卡盘chuck材料去除装备Material removal equipment插入式磨削Plug-in grinding冷却液coolant 床头箱headstock二翻译句子1) The slides a nd slideways of a machine tool locate and guide members which move relative to each other,usually changing the position of the tool relative to the workpiece.车刀机床的滑块和滑道s使定位和导向构件之间将对移动，常常用于改变工件与工作台的相对位置2）In order to maintain a constant angular velocity, the individual tooth profile must obey the fundamental law of gearing: for a pair of gears to transmit a constant angular velocity ratio, the shape of their contacting profile must be such that the common normal passes through a fixed point on the line of the centers为了维持一个恒定的角速度,单个齿廓必须遵守啮合基本定律:对于一对以固定角速度传动的齿轮,他们的传动比两轮连心线被齿廓接触点公共法线分割的两顿先吨的反比3）Plain milling cutters are adapted to cut by teeth with cutting edges situatued on the surface of a cylinder which can be circumscribed on cutter. face mills are adapted to cutting by teeth with cutting edges situated on the surface of the mill and partially on its cylindrial surface平铣刀适用于使用位于圆柱面上的齿上的切削刃工作的铣削，平面铣刀适用于使用位于铣刀表面和其部分圆柱面的齿上的切削刃做的铣削4）Pressures angles for spur gear are usually 14.5 or 20 degrees, although other values can be used. Meshing gears must have the same pressure angles.虽然其他值也也可以使用，但齿轮的压力角经常为14.5度或20度，相啮合的齿轮必须有相同的压力角5）The cross section of the milled surface corresponds to the outline or contour of the milling cutter or combination of cutters used.加工表面的界面要与使用的刀具或组合刀具的外轮廓一致6）Lets us now discuss the different concepts associated with the manufacturing accuracy required modern mass-production technologies.让我们来讨论有关现代大规模生产技术所要求的制造精度的不同概念。