机械专业英语(第三版)第4章
机械专业英语第三版课后答案
机械专业英语第三版课后答案1、There is _______ meat in the fridge.Lets go and buy some. [单选题] *A. little(正确答案)B. a littleC. fewD. a few2、85．You’d better? ? ? ? ? a taxi, or you’ll be late. [单选题] * A．take(正确答案)B．takingC．tookD．to take3、The rain is very heavy _______ we have to stay at home. [单选题] *A. butB. becauseC. so(正确答案)D. and4、--Why are you late for school today?--I’m sorry. I didn’t catch the early bus and I had to _______ the next one. [单选题] *A. wait for(正确答案)B. ask forC. care forD. stand for5、Ladies and gentlemen, please fasten your seat belts. The plane _______. [单选题] *A. takes offB. is taking off(正确答案)C. has taken offD. took off6、Look! There are some boats ______ the river.（）[单选题] *A. on(正确答案)B. overC. betweenD. in7、She passed me in the street, but took no（）of me. [单选题] *Attention (正确答案)B. watchC. careD. notice8、The story has _______ a lot of students in our class. [单选题] *A. attracted(正确答案)B. attackedC. appearedD. argued9、This is the news _______ you want to know. [单选题] *A. that(正确答案)B. whatC. whenD. who10、—Is this ______ football, boy? —No, it is not ______.（）[单选题] *A. yours; myB. your; mine(正确答案)C. your; meD. yours; mine11、If you don’t feel well, you’d better ask a ______ for help. [单选题] *A. policemanB. driverC. pilotD. doctor(正确答案)12、We had ____ wonderful lunch last Saturday. [单选题] *A. /B. theC. oneD. a(正确答案)13、67．—What can I do for you?—I'm looking at that dress.It looks nice.May I ________？[单选题] *A．hold it onB．try it on(正确答案)C．take it offD．get it off14、During the Spring Festival, people in Northern China usually eat _______ as a traditional Chinese food. [单选题] *A. pizzaB. dumplings(正确答案)C. hamburgersD. noodles15、26．There’s some fruit in the kitchen. We ________ buy any. [单选题] *A．need toB．needn’t toC．don’t needD．don’t need to(正确答案)16、We have _______ a double room with a bath for you in the hotel. [单选题] *A. boughtB. reserved(正确答案)C. madeD. taken17、—______ Tom play the piano?—Yes, very well. （）[单选题] *A. Can(正确答案)B. MayC. MustD. Should18、My dog is very _______. It is safe to touch it if you want to. [单选题] *A. luckyB. deliciousC. friendly(正确答案)D. helpful19、When Max rushed to the classroom, his classmates _____ exercises attentively. [单选题] *A. didB. have doneC. were doing(正确答案)D. do20、What time _______ he get home every day? [单选题] *A. isB. does(正确答案)C. doD. am21、—What can I do to help at the old people’s home?—You ______ read stories to the old people. （）[单选题] *A. could(正确答案)B. mustC. shouldD. would22、( )He gave us____ on how to keep fit. [单选题] *A. some advicesB. some advice(正确答案)C. an adviceD. a advice23、Our campus is _____ big that we need a bike to make it. [单选题] *A. veryB. so(正确答案)C. suchD. much24、—Tony, it’s cold outside. ______ wear a jacket?—OK, mom.（）[单选题] *A. Why not(正确答案)B. Why don’tC. Why did youD. Why do you25、What did you _______ at the meeting yesterday? [单选题] *A. speakB. tellC. say(正确答案)D. talk26、—What’s wrong with you, Mike?—I’m really tired because I studied for today’s test ______ midnight last night. （）[单选题] *A. althoughB. unlessC. until(正确答案)D. so that27、--_______ does Ben go to school?--By bus. [单选题] *A. How(正确答案)B. WhatC. WhereD. Why28、37．—What will you be ___________?—I'm not sure. Maybe I'll be a doctor like my father. [单选题] *A．right nowB．in the future(正确答案)C．at onceD．at the moment29、The family will have _______ good time in Shanghai Disneyland. [单选题] *A. theB. a(正确答案)C. anD. /30、32．There are about __________ women doctors in this hospital. [单选题] *A．two hundred ofB．two hundreds ofC．two hundredsD．two hundred (正确答案)。
机械专业英语3-4[59P][2.47MB]
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Unit6 Nontraditional Machining Processes
• The main attraction of EDM over traditional machining processes such as metal cutting using different tool and grinding is that this technique utilizes thermoelectric process to erode undesired materials from the workpiece by a series of rapidly recurring discrete electrical sparks between workpiece and electrode. 相比利用不同刀具进行金属切削和磨削的常规加工而言，电火花 加工的吸引人之处在于它利用工件和电极之间一系列重复产生的 （脉冲）离散电火花所产生的热电作用从工件表面通过电腐蚀去 除掉多余的材料。
Scientific notation
• • • • 103 :ten to the power of three. 7.39×106 :seven point three nine times ten to the power of six. 82600=8.26×10×10×10×10=8.26×104 This is an equation, which reads eighty-two thousand, six hundred equals eight point two six times ten, times ten, times ten, times ten equals eight point two six times ten to the power of four. • 3×10-5: three times ten to the power of minus five.
机械专业专业英语词汇
《机械工程专业英语》词汇Chapter One Mechanics Components 第一章机械构件 Lesson One 第一课齿轮 Words and Expressions1.spur gear 直齿轮2.thermal expansion 热膨胀3.lubrication润滑4.backlash倾向间隙5.the pitch circles节圆6.space width间隙宽度7.instrument gear仪表齿轮8.the split gear拼合齿轮9.helical gear斜齿轮10.pitch-line velocities节线速度11.an axial thrust轴向推力12.blank 坯件13.double-helical gears 人字齿轮14.non-intersecting不相交的15.worm gears蜗轮蜗杆16.bevel gears伞齿轮17.crossed-axis交叉轴18.nut 螺母19.screw丝杠螺钉rge rations 大速比21.parallel-shaft gears平行轴齿轮22.single-thread worms单线蜗杆23.lead angles导角24.multiple-thread worms多线蜗杆25.hypoid gear偏轴伞齿轮26.rolling Cones滚锥27.involutes渐开线，Lesson Two Rolling Guides and Bearings 第二课滚动导轨和轴承Words and Expressions1.rolling guides (rolling guideways) 滚动导轨2.plain guides普通导轨3.a roller chain滚柱链4.cape保持架5.guide surfaces导轨面6.stiffness 刚性7.load-carrying capacity 载荷能力8.rolling-contact bearings滚动轴承9.ball bearing球轴承10.an inner race 内座圈11.an outer race外座圈12.separator 隔离环13.curvature曲率14.notch 凹槽15.thrust load 推力负载16.a radial ball bearing经向球轴承17.sections断面18.an axial-thrust bearing轴向推力轴承19.washer 垫圈20.roller bearing 滚子轴承21.tapered 锥形的22.spherical球面的23.retaining shoulder 定位肩24.needle bearing滚针轴承25.tapered roller bearings锥形滚子轴承26.spherical roller bearings 球面滚子轴承27.concave凹面的28.convex凸面的Lesson Three Clutches第三课离合器Word and Expressions1.coaxial (coaxial) 同轴的，共轴的2.a rotatable shaft (driven shaft) 从动轴3.a rotating shaft (driving shaft) 主动轴4.friction clutches磨擦离合器5.ring-shaped环形的6.spring弹簧7.a conical spool锥形短管轴8.coefficient of friction磨擦系数9.facing衬片10.dry clutches干式离合器11.wet clutches 湿式离合器12.a multiple-plate disc clutch多片式圆盘离合器13.spline花键14.pivot枢轴15.magnetic clutches电磁离合器16.an annular gap环状间隙17.powder iron铁粉18.graphite石墨19.direct-current control coil直流控制线圈20.slippage滑动Lesson Four Ball screw and nuts 第四课滚珠丝杠螺母副Words and Expressions1.precision ball screw assembly 精密滚珠丝杠副2.auto-drafting machines自动制图机3.valves阀门4.metallurgical machinery冶金机械5.satellite tracers卫星跟踪仪6.steering gears转向机构7.stick-slip 爬行循环8.rolling guideways滚动导轨9.recirculating-ball screw滚珠丝杠10. feed mechanisms 进给机构11. wear 磨损12. damping property 阻尼性13. tangential 切向的14. circumferential 圆周的15. thread pitch螺距16. a ball-return track回珠滚道17. a return tube回珠管18. shock-free无冲击19. stiffness刚性20. freedom from免除21. pre-load预载Chapter Two Constructure and Technology of Machine Tools第二章机床结构及工艺Lesson One Size, Bed and Tailstock of Engine lathe第一课普通车床的尺寸、床身及尾架Words and Expressionsthe (turning lathe, engine lathe, tuning machine) 车床2.the live center point 活顶尖3.swing 回转直径4.bed 床身5.ways导轨6.Carriage 床鞍7.Cross-feed slide 横进给刀架8.Headstock主轴箱9.tailstock. 尾架10. rack 齿条11. pinion gear小齿轮12. handwheel 手轮13. hardened steel 淬火钢14. flame-hardened ways 火焰淬火导轨15. the distance between centers项尖距16. taper shank锥形车削17. tailstock spindle 尾架锥柄18. taper shank 套筒19. three-jaw chuck三爪卡盘20. roller bearing滚子轴承21. lubrication润滑22. workpiece工件Lesson Two Headstock of Engine Lathe第二课普通车床的主轴箱Words and Expressions1.spindle 主轴2.taper sleeve锥套3.live center轴心活顶针4.the threaded spindle nose螺纹主轴头5.the cam lock spindle nose凸轮锁紧主轴头6.the long taper key drive spindle nose长锥键传动主轴头7.flange法兰盘8.Chuck卡盘9.Cam lock stud、凸轮锁紧短轴10. Collar 轴环11. faceplate套圈12. keyway花盘，键槽13. back gear背轮14. bull gear 大齿轮15. sliding pit滑动槽16. groove、槽17. step pulley塔轮18. drive pulley主动轮19. driven pulley被动轮20. gear box齿轮变速箱Lesson Three Carriage, Feeding and Threading Mechanism of Engine Lathe第三课普通车床的床鞍、进给和车螺纹机构 Words and Expressions1.Saddle鞍座2.Apron 滑板箱3.Cross slides 横向滑板，横刀架pound rest 复合刀架（转盘）5.tool post小刀架6.tool holder 刀夹7.Clutch 离合器8.Facing 车端面9.Cutoff 切断机动进给10. power feed 动力进给11. split nut (half-nut) 开合螺母12. dovetail way 燕尾导轨13. micrometer collar 千分尺套圈摇柄14. rocker 摇臂15. threading 车螺纹16. gear box 齿轮箱，传动箱17. ring collar 刻度环18. an index chart 指示图19. lead screw丝杠20. feed rod 光杠21. Cross-feed横进给22. Longitudinal feed 纵向进给23. acme threads 梯形螺纹24. right-hand thread右旋螺纹25. left-hand thread 左旋螺纹Lesson Four Word-holding attachments for the lathe and Rough turning第四课车床工件夹紧附件和粗车Words and Expressions1.attachment 附件2.four-jaw independent chuck 四爪单动卡盘3.Collar chuck 套爪卡片4.follower rest 跟刀架5.reducing sleeve 中心架the dog 异径套筒7.bent-tail dog 车床卡爪8.Rough turning 曲尾卡爪9.Rough turning粗车white lead白铅粉Center height中心高end副后角relief后角Clearance angle留隙角 back rake 纵向前角tangent切线caliper卡尺trial cut试切overload过载、Lesson Five Milling Shaper, Planer and Grinding Machines第五课铣床、刨床和磨床Words and Expressionsling machines 铣床ling cutter 铣刀刀杆3.arbor 心轴4.spacer 垫圈、垫片5.bushing套6.yoke 支座7.starting lever 起动手柄8.Knee升降台9.elevating screw 升降丝杆10. index head分度头11. foot stock 分度头支座12. Universal Milling Machine 万能铣床13. Shaper牛头刨床14. plane 龙门刨床15. ram 滑轨16. vise 台钳17. fixture 夹具18. notched wheel or ratchet 棘轮19. pawl 棘爪20. cross rail 横梁21. grinding machine 磨床22. grinding wheel 砂轮23. finish 光洁度24. Cutter grinder 工具磨床25.surface grinder 平面磨床26.centreless grinder 无心磨床27.internal grinder 内圆磨床28.external grinder 外圆磨床29.Wheel head磨头Lesson Six Machine Tool Tests, Accuracy checking and Maintenance 第六课机床试验，精度检验及保养Words and Expressions1.acceptance tests 验收试验2.certificate data 检验证数据3.geometrical accuracy几何精度4.surface roughness 表面粗糙度5.vibration-proof 防振6.straightness 平直度7.flatness 平面度8.upright立柱9.base plate 底板10. deviation 偏差11. parallelism 平行度12. squareness垂直度13. servicing 维修14. inspection检查15. repairs 检修16. maintenance 保养17. rapidly wearing components 易损件18. post-inspections repairs 后检查修理19. periodic repairs定期检修20. routine servicing 日常维修21. general overhaul 大修22. restoration修复Chapter Three Modern Manufacturing Engineering &Development第三章现代制造技术及其发展Lesson One The development of NC 第一课数字控制的发展 Words and Expressions1.vacuum tube 真空管2.electrical relay 继电器3.interface 接口4.integrated circuit(IC) 集成电路5.hardware 硬件6.Read Only Memory(ROM) 只读存储器7.Machining Center 加工中心8.Turning Center车削中心9.electrical discharge machining电火花加工10.drafting制图11.printed circuit(PC) 印刷电路12.robot机械手，机器人13.Subroutine子程序14.tape reading纸带读数15.alarm 报警16.diagnostic message诊断信息17.Constant surface speed control 恒线速控制18.polar coordinate 极座标19.interpolation插补20.microprocessor微处理机21.servo drive伺机服驱动22.pre-amplifier前置放大器23.point-to-point点位24.contouring轮廓控制25.bubble memory磁泡存储器26.macro宏指令27.canned cycle固定循环Lesson Two Open-loop and closed-loop servo drives第二课开环和闭环伺服驱动Words and Expressionsrmation command section 信息命令段2.punched tape code穿孔带码3.magnetic tape code 磁带码4. input data 输入数据5.open-loop开环6.closed-loop 闭环7.automatic washing machine自动洗衣机8.power supply level电源电平9.feedback 反馈10. resolution清晰度11. deterioration恶化，变坏12. discrepancy差误13. subtract logic减法逻辑14. command position counter 指令位置计数器15. drive signal amplifier 伺服信号放大器16. transducer 传感器17. synchro 同步机18. shaft digitizer轴数字读出器19. analog模拟量digital数字式self-correcting自动修正light interruption光中断photo cell光电管electric pulse电脉冲increment增量encoder编码器binary二进制Gray code格雷码Segmentation扇区Lesson Three Hydraulic motors and servo motors第三课液压马达和伺服电机Words and Expressions1.hydraulic motor 液压马达2.oil sump 油箱，油槽3.oil pressure pump 油压力泵4.hydraulic cylinder 液压缸5.valve 阀6.oil flow 油流7.hydrostatic drives 水力驱动，静压驱动8.variable-delivery pump9.piston 活塞10. reciprocating movement 往复运动11. supply line 供应线12. return line 回程线13. the filling cycle14. servomotors 伺服电机15. input command signals 输入命令符号16. step-by-step motors 步进电机17. Phase-shifted18. Amplifier 放大器19. Contact 触点，接头20. Electromagnet 电磁铁。
机械工程专业英语__第4课
2）形容词或“形容词+介词”转换为 动词
We are also familiar with other transformations of energy.
我们还熟悉别的能量转换现象。
The force is perpendicular to the surface. 此力垂直于表面。
翻译的基本方法 – 转换词性 Skills of Translation –transform part of speech
转换词性是根据翻译的需要将英语某一词性的词译为汉语 另一词性的方法。
例：The workers have succeeded in making high quality semiconductor devices of all types.
1. 转换为名词
1）动词转换为名词
Has the house been wired for electricity? 这房子的电线装好了吗？（动词wired 译为“装
线”“给…装电线”） Vacuum rectifiers are characterized by the following. 真空整流器具有如下的特性。 Properties of non-metals vary widely. 非金属材料的各种性能有很大的差异。(不宜译为
3) 副词转换为名词
Sodium and copper have one electron in the outer shells and are chemically similar.
钠和铜在外壳上具有一个电子，因而其化学性 质相似。（不说“化学地相似”而是将 chemically 译为“化学性质”）
2. 转换为动词
4机械工程专业英语第四课
4机械工程专业英语第四课翻译的基本方法–增词与减词Skills of Translation –adding and reducing words三、增词与减词（一）增词译法:在对英文进行翻译时，若按字面翻译，句子的结构不完善，或句子的含义不明确，或词汇的概念不清晰时，需要增加某些词语，以便更完善、清楚地表达英语句子的内容。
例：Efficiency costs money, safety adds complexity, performanceincreases weight.直译：效率花费金钱，安全增加复杂性，性能增加重量。
增词译法：对设备(或器件)来说，要提高效率就要增加成本，要想保证安全势必要增加其复杂程度，而要改善性能就要增加其重量。
1. 增加表示时态的概念的词英语中表达时态的词往往是没有词义的，翻译时必须用一些中文词将其表达出来：Balloons were (and are) usually filled with hydrogen.气球过去（和现在）一般都用氢气来充气。
翻译的基本方法–增词与减词Skills of Translation –adding and reducing wordsWe can learn what we did not know.我们能够学会我们原来不懂的东西。
（过去时）The generator set will start working tomorrow.这台发电机组将于明天开始运行。
（将来时）An object is said to possess kinetic energy if it if moving.如果一个物体在运动，就可以说它有了动能。
（进行时）We have learned how to fit the computer.我们已经学会了怎样安装电脑。
（完成时）Reamers are used to finish drilled holes.绞刀用来将已经钻好了的孔进行精加工。
机械专业英语Unit4-教案
机器人专业英语机器人专业英语主要教学步骤和教学内容课程回顾：回顾Surface Roughness相关方面的内容新课讲授：In the early days of engineer, the mating of parts was achieved by machining one part as nearly as possible to the required size, machining the mating part nearly to size , and then completing its machining, continually offering the other part to it, until the desired realatin-ship was obtained 1 . If it was inconvenient to offer one part to the other part during machining, the final work was done at the bench by a fitter, who scraped the mating parts until the dessired fit was obtained, the fitter therefore being a “fitter” in the literal sense.在早期的工程（问题）中，配合零件获得的方法是，首先尽可能把一个零件加工到所需尺寸，再将与它配合的零件加工到接近所需尺寸，不断将这两个零件进行试赔，再进一步加工纸获得所需配合的尺寸。
假若在加工中不便于将一个零件与另外一个零件进行试配，那么最后的工作是有钳工在钳工台上完成，钳工刮削配合零件直至达到所需配合，所以“钳工”一词在英语中的意思为“装配者”。
It is obvious that the two parts would have to remain have to remain together, and in the event of one having to be replacecd, the fitting would have to be done all over again. In these days, we expect to be able to purchase a replacement for a broken part, and for it to function correctly without the need for scraping and other fitting operations.显然，两个配合件应该总在一起（工作），当其中任意一个需要替换时，所有的适刮削工作有要从头重做。
电子课件英语第三版Unit4
Why do we learn English? We learn English because it is one of the world’s most widely used languages. It is not only the language of Britain but also of Canada, the U.S.A., Australia and New Zealand. It is used by millions of people in Africa and Asia as well. Today, it is the international language of trade, and most important of all, the language of service. With the help of English, we can communicate with people of many countries.
But how can we learn English well? Think of what a child does. He/She listens to what people say and he tries to copy what he hears. He/She uses the language, talks and thinks in it all the time. It is important to remember that we learn language by listening. It is best to learn all the new words by ear. We can read them, spell them and write them later. If we work hard at it, we can certainly overcome all the difficulties and learn English well.
机械工程专业英语Unit 4
❖ One of the basic operations of hammer forging is the elongation of a piece of metal by stretching with hammer blows, causing it to become thinner and longer. 锤锻中常用开式模锻。在锤锻中零件通过锤击辅之以相对简单的 工具成型。其中包括开式锻模。锤锻的基本操作之一就是通过锤击使 金属伸长，促成其变细变长。
❖ Advantage：can produce components Байду номын сангаасf greater complexity and accuracy, with a better surface finish, than the more traditional methods not using closed dies. 优点：闭式模锻能生产高度复杂和精确的零件，而且表面光洁度要 比不用闭式锻模的更传统方法好。
它们均利用下落重量来产生金属成型所需的压力。锻造大零件则要 用到蒸汽、压缩空气、液压或电力驱动的锻压机。大型的自动化锻机用 于工程零件的批量生产。
open-die forging &closed-die forging 开式锻模和闭式锻模
1. open-die forging 开式锻模
❖ open-die forging, usually in the form of hammer forging.
Unit 4 Forging Processes
机械专业英语董建国第4章
Unit 4
backlash eliminate recommend cast [5bAklAF] [I5lImIneIt] [rekE5mend] [kB:st; (?@) kAst] n. 间隙，轮齿隙 vt. 排除，消除 vt. 推荐，介绍 n. 铸件 v. 铸造 casting forge [fC:dV] n. 铸造，铸件 n. 锻工车间
Unit 4
NEW WORDS AND EXPRESSIONS
conventional [kEn5venFEn(E)l] adj. 一般的，常规的
VS=versus
climb
[5vз:sEs]
[klaIm]
prep. 对，与…相对
v.&n. 攀登，爬
i.e.=that is
regard recognize acceptable [rI5^B:d] [5rekE^naIz] [Ek5septEb(E)l]
Unit 4
These supports are of great rigidity.
这些支架具有很大的刚性。 This machine is not of a heavy-duty type. 这台机器不属于重型的。
Unit 4
EXERCISES
1．Discuss the following questions in English: (1) What is the conventional milling?
above its critical range and then quenching it in a suitable medium such as water, brine, oil, or some other liquid. Having been hardened, the metal must be given a tempering treatment which consists of reheating the hardened steel to a temperature below the critical range, thus producing the required physical properties. Mr. Liu: And what is critical temperature?
机械工程专业英语P33-英文版
Engineering drawing is a graphical language used by engineers and other technical personnelassociated with the engineering profession. The purpose of engineering drawing is to conveygraphically the ideas and information necessary for the construction or analysis ofmachines ,structures，or systems.In colleges and universities，engineering drawing is usually treated in courses with titleslike Engineering Graphics．Sometimes these courses include other topics，such as computergraphics and NomographyThe basis for much engineering drawing is orthographic representation (projection). Objectsare depicted by front, top, side, auxiliary, or oblique views, or combinations of these.The complexity of an object determines the number of views shown. At times, pictorial viewsare shown.Engineering drawings often include such features as various types of lines, dimensions,lettered notes, sectional views, and symbols. They may bein the form of carefully plannedand checked mechanical drawings, or they may be freehand sketches. Usually a sketchprecedes the mechanical drawing. Final drawings are usually made on tracing paper, cloth orMylar film, so that many copies can be made quickly and cheaply by such processes as,blueprinting, ammonia-developed printing, or lithography.Many objects have complicated interior details which cannot be clearly shown by means offront, top, side, or pictorial views. Section views enable the engineer or detailer to showthe interior detail in such cases. Features of sectiondrawings are cutting-plane symbols,which show where imaginary cutting planes are passed to produce the sections, and section-lining (sometimes called cross-hatching), which appears in the section view on all portionsthat have been in contact with the cutting plane. When only a part of the object is to beshown in section, conventional representation such as a revolved, rotated, or broken-outsection is used. Details such as flat surface, knurls, and threads are treatedconventionally, which facilities the making and reading of engineering drawings byexperienced personnel. Thus, certain engineering drawings will be combinations of top andfront views, section and rotated view, and partial or pictorial views.In addition to describing the shape of objects, many drawings must show dimensions, so thatworkers can build the structure or fabricate parts that will fit together. This isaccomplished by placing the required values (measurements) along dimension lines (usuallyoutside the outlines of the object) and by giving additional information in the form ofnotes which are referenced to the parts in question byangled lines called leaders. Indrawings of large structures the major unit is the foot, and in drawings of small objectsthe unit is the inch. In metric dimensioning, the basic unit may be the meter, or themillimeter, depending upon the size of the object or structure.Working types of drawings may differ in styles of dimensioning, lettering (inclinedlowercase, vertical uppercase, and so on), positioning of the numbers (aligned, orunidirectional –a style in which all numbers are lettered horizontally), and in the typeof fraction used (common fractions or decimal fractions).If special precision is required,and upper and lower allowable limit are shown. Such tolerance, or limit, dimensioning isnecessary for the manufacture of interchangeable mating parts, but unnecessarily closetolerances are very expensive.Layout Drawings Layout drawings of different types are used in different manufacturingfields for various purposes.One is the plant layout drawing,in which the outline of the building,work areas, aisles, and individual items of equipment areall drawn to scale. Another typeis the aircraft, or master,layout, which is drawn on glass cloth or on steel or aluminum sheets.The object is drawn to full size with extreme accuracy. The completed drawing is photographed with great precision, and a glass negative made. Fromthis negative,photo templates are made on photosensitized metal in various sizes and for differentpurposes,thereby eliminating the need for many conventional detail drawings.Another type of layout, or preliminary assembly, drawing is the design layout, which establishes the position and clearance of parts of anassembly.A set of working drawings usually includes detail drawings of all parts and an assemblydrawing of the complete unit. Assembly drawings vary somewhat in character according totheir use, as design assemblies or layouts; working drawing assemblies; general assemblies;installation assemblies; and check assemblies. A typical general assembly may includejudicious use of sectioning and identification of each part with a numberedballoon. Accompanying such a drawing is parts list, in which each part is listed by numberand briefly described; the number of pieces required isstated and other pertinentinformation given. Parts lists are best placed on separate sheets and typewritten to avoidtime-consuming and costly hand lettering.Schematic or diagrammatic drawings make use of standard symbols and single lines betweensymbols which indicate the direction of flow. In piping and electrical schematic diagrams,symbols recommended by the American National Standards Institute (ANS I), other agencies,or the Department of the Defense (DOD) are used. The fixtures or components are not labeledin most schematics because readers usually know what the symbols represent.Additional information is often lettered on schematic drawing, for example, theidentification of each replaceable electrical component. Etched-circuit drawing hasrevolutionized the wiring of electronic components. By means of such drawing, the wiring ofan electronic circuit is photographed on a copper-clad board, and unwanted areas are etchedaway. On electrical and other types of flow diagrams, all single lines (often with arrowsshowing direction of flow) are drawn horizontally or vertically; there are few exceptions.In some flow diagrams, rectangular enclosures are used for all items. Lettering is usuallyplaced within the enclosuresStructural Drawings Structural drawings include design and working drawings for structuressuch as buildings, bridges, dams, tanks, and highways. Such drawings form the basis oflegal contracts. Structural drawings embody the same principles as do other engineeringdrawings, but use terminology and dimensioning techniques different from those shown inprevious illustrations.1工程图是一种图形语言使用的工程师和其他技术人员与工程相关的职业。
新编英语教程第三版unit4
新编英语教程第三版unit4Unit 4Language StructureMain Teaching Points:1.Modal auxiliaries may/might used to express “possibility”eg. It may/might be fine tomorrow.2.Modal auxiliaries should/ ought to expressing “obligation”eg. He should/ought to get up early and take some exercise every day. 3.Modal auxiliaries would rather expressing “preference”eg. I would rather do some reading.4.Modal auxiliaries must and can’t used to express “strong probability”and “impossibility” respectivelyeg. He must be in the gym. // He can’t be there.Useful Expressionsgo-mountain climbing be in good healthtake notice of be weak in / be poor insuffer from sth. live transmission of sports eventsDialogue A Trip to ChinaA. Listening to the recordingB. Questions on specific detailsC. Broad questions:1. Describe the changes in China’s rural areas, particularly in the coastal areas.2. What are the ways in which Chinese farmers get up-to-dateinformation?3. Why college education important for modern farmers?4. Do you believe in “You get what you put in”?D. Language Points1. Fancy meeting you here.=It’s a surprise to meet you here.2. world-renowned/ world-famous世界闻名的eg. 1) Shanghai is a world-renowned cosmopolitan metropolis.上海是国际知名的大都会。
机械专业英语课件4
Paragraph 7:
Washers(垫片、垫圈) are often used with threaded fasteners to provide a better bearing surface for nuts and bolt heads, to provide a bearing surface over large clearance holes(光孔) or slots, to distribute the load over a larger area, to prevent marring of parts during assembly, to improve torque-tension ratio (by reducing friction), and to provide locking, in some cases through spring action.
Thus the connection remains tight unless some external influence such as vibration or temperature change overrides the initial condition.
这样只要没有像振动、温度变化这些外部因素改变初 始条件，这种联接就能维持紧固的状态。
1
Paragraph 1
Threaded fasteners perform the function of locating, clamping, adjusting and transmitting force from one machine member to another.
螺纹紧固件起着定位、加紧、调整和从一个机器零 件向另一个传递力的作用。
机械专业英语(第三版)第4章
Unit 4
2．The more carbon the steel contains and the quicker the cooling is, the harder it becomes. 钢的含碳量越高，冷却速度越快，钢就变得越硬。
Unit 4
High carbon steels may be hardened by heating it to a certain temperature and then quickly cooling in water. The more carbon the steels contains and the quicker the cooling is, the harder it becomes. Because of its high strength and hardness this grade of steel may be used for tools and working parts of machines.
Unit 4
2．Alloy steels (1) Special alloy steel, such as nickel, chromium steel; (2) High-speed steel also known as self-hardening steel. Carbon steels are the most common steels used in industry. The properties of these steels depend only on the percentage of carbon they contain. Low carbon steels are very soft and can be used for bolts and for machine parts that do not need strength. Medium carbon steels are a better grade and stronger than low carbon steels. It is also more difficult to cut than low carbon steels.
机械类专业英语应用Unit 4
• compass [ˈkʌmpəs] n.
• perplex [pəˈpleks] vt. • mechanism [ˈmekənizəm] n.
罗盘； 指南针； 圆规； 界限
使迷惑， 使混乱； 使复杂化 机构； 机械装置
words and expressions
• oblique views • pictorial views
描述；描绘，描画
斜视图 插图， 视图
• sectional views
• mylar ['maiˌlɑ:] n. • blueprint [ˈblu:print] n.& vt.
剖视图
聚脂薄膜 蓝图，设计图；为…制蓝图
words and expressions
words and expressions
• auxiliary view • orthographic view
辅助视图 正视图
• allow for
• perpendicular [ˌpiəːp(ə)n'dikjulə] adj.& n. • isometric view
允许有； 考虑到； 体谅； 留出
• • • • • • • • ammonia [əˈməuniə] n. ammonia-developed diazo [dai'æzəu] n. & adj. lithography [liˈθɔgrəfi] n. section-lining/ cross-hatching knurl [nə:l] n. thread [θred] n. & vt. dimension [diˈmenʃən] n. & adj. & vt. 氨； 氨水； 氨气 氨水显影的 重氮基；二氮化合物的 石印； 平版印刷术 剖面线 滚花； 硬节 螺纹； 线；将（针、线等）穿过… 尺寸； 维； 标出尺寸
机械英语阅读 Unit Four (4)
学习单元4-1
（1）According this passage, the correct answers are
□ Every product we use in our daily life has undergone machining process.
□ Most machining cost is spent annually on machining and related operations.
□ Machine tools used in the manufacturing industry have all undergone metal cutting.
□ Metal cutting is very important in general manufacturing.
□ Different requirement selects different machining methods.
[rɪˈvɜ:s] 倒退，反向，反面 lathe [leɪð] 车床，机床 beneath [bɪˈni:θ] 在….下方 shaper [‘ʃeɪpə] 塑造者 planer [ˈpleɪnə(r)] 刨床 extremely [ɪkˈstri:mli] 非常的，极端的 circular saw [ˈsə:kjulə sɔ:] 圆锯 slot [slɒt] 槽，插槽 variety [vəˈraɪəti] 多样，种类，变化
➢ Step2：学生要完成专业词汇的中英文配对训练 （ Maching the Terms ）。
➢Step3：正确使用常用专业英文短语（ Working with the Expressions ）。
➢ Step4：用简单语句正确表达复杂语句的信息 （ Rewriting the Complex Sentences ）。
2019年机械工程专业英语教程课后题翻译_1-4单元.doc
Unit 1Two methods of designating limit dimensions are considered as standard .One method is the maximum material method in which the large dimensions is placed above the smaller dimension for male parts, and the reverse is true for female parts. This method is well suited for small lot quantities because it is likely that the machinist himself may check the dimensions of the parts. In so doing, he will be verifying initially the larger dimension of the male part and the smaller dimension of the female part. The other method is the maximum number method and is preferred by production and quality control departments. In this method of designating a dimension, the larger number is always placed above the smaller number, regardless of whether the part is male or female.这两种极限尺寸方法指定为标准。
一个方法是最大的材料的方法，大尺寸放在上面的较小尺寸的凸圆零件，而相反的是真正的凹槽部分或内孔零件。
机械工程专业英语 第四课文及阅读材料
Lesson 5 lathe, shaper, grinding andmilling machine1, lathes and lathe operationsLathes are generally considered to be the oldest machine tools . although woodworking lathes were originally developed during the period 1000-1 B.C., metalworking lathes with lead screws were not built until the late 1700s .the most common lathe (figure 2.1) was originally called engine lathe because it was powered with overhead pulleys and belts from nearby engines . today these lathes are set up with individual electric motors.1)Lathe componentsLathes are equipped with a variety of components and accessories . the basic components of a common lathe are described below.i)BedThe bed supports all major components of the lathe. Beds have a large mass and are rigidly built ,usually from gray or nodular cast iron . the top portion of the bed has two ways , with various cross-sections ,that are hardened and machined for wear resistance and dimensional accuracy during use .ii)CarriageThe carriage ,or carriage assembly ,slides along the ways and consists of an assembly of the cross-slide , tool post ,and apron .thecutting tool is mounted on the tool post ,usually with a compound rest that swivels for tool positioning and adjustment . the cross-slide moves radially in and out ,controlling the radial position of the cutting tool in operations such as facing. The apron is equipped with mechanisms for both manual and mechanized movement of the carriage and the cross-slide by means of the lead screw .iii)HeadstockThe headstock is fixed to the bed and is equipped with motors , pulleys , and V-belts that supply power to the spindle at various rotational speeds . the speeds can be set through manually-controlled selectors .most headstocks are equipped with a set of gears ,and some have various drives to provide a continuously variable speed range to the spindle. Headstock have a hollow spindle to which workholding devices ,such as chucks and collets ,are attached , and long bars or tubing can be fed through for various turning operations .iv)TailstockThe tailstock ,which can slide along the ways and be clamped at any position ,supports the other end of the workpiece . it is equipped with a tailstock center that may be fixed (dead tailstock center) or may be free to rotate with the workpiece (live tailstock center ) . drills and reamers can be mounted on the tailstock quill(a hollow cylindrical part with a tapered hole ) to drill axial holes in theworkpiece.v)f eed rod and lead screwthe feed rod is powered by a set of gears from the headstock .it rotates during the operation of the lathe and provides movement to the carriage and the cross-slide by means of gears ,a friction clutch , and a keyway along the length of the rod . closing a split nut around the lead screw engages it with the carriage . it is also used for cutting threads accurately.vi)Workholding devicesWorkholding devices are particularly important in machine tools and machining operations .in a lathe , one end of the workpiece is clamped to the spindle by a chuck , collets , face plate , or mandrel.vii)AccessoriesSeveral devices are available as accessories and attachments for lathes. Among these devices are the following:Carriage and cross-slide stop with various designs to stop the carriage at a predetermined distance along the bed.Devices for turning parts with various tapers or radiiMilling , sawing, gear-cutting, and grinding attachments ,and various attachments for boring ,drilling ,and thread cutting .2)Lathe turningIn a typical turning, the workpiece is clamped by any workholdingdevices described. Long and slender parts should be supported by a steady rest and follow rest placed on the bed ,otherwise, the part will deflect under the cutting forces. These rests are usually equipped with three adjustable fingers or rollers , which support the workpiece while allowing it to rotate freely . steady rests are clamped directly on the ways of the lathe , whereas follow rests are clamped on the carriage and travel with it .The cutting tool ,attached to the tool post , which is driven by the lead screw ,removes material by traveling along the bed , a right-hand tool travels toward the headstock , and a left-hand tool toward the tailstock. Facing cutting are done by moving the tool radially with the cross-slide, and clamping the carriage for better dimensional accuracy. 2,milling machine and millingMilling includes a number of highly versatile machining operations capable of producing a variety of configurations (figure 2.2) with the use of a milling cutter , a multitoothed cutter that produces a number of chips in one revolution .1)Milling operationsi)slab millingin slab milling ,also called peripheral milling , the axis of cutter rotation perpendicular to the workpiece surface to be machined (figure2.2(a)) . the cutter ,generally made of high-speed steel , has anumber of teeth along its circumference, each tooth acting like a single-point cutting tool called a plain millii)face millingin face milling ,the cutter is mounted on a spindle having an axis of rotation perpendicular to the workpiece surface(figure 2.2(b)) . because of the relative motion between the cutting teeth and the workpiece , a face-milling cutter leaves feed marks on the machined surface similar to those left by turning operations . note that surface roughness of the workpiece depends on insert corner geometry and feed per tooth.iii)End millngFlat surfaces as well as various profiles can be produced by end milling . the cutter in end milling is shown in figure 2.2(c) . it has either straight or tapered shanks for smaller and larger cutter sizes , respectively . the cutter usually rotates on an axis perpendicular to the workpiece ,although it can be tilted to machine-tapered surfaces.In conventional milling ,also called up milling ,the maximum chip thickness is at the end of the cut (figure 2.3(a )). The advantages to conventional milling are that (a ) tooth engagement is not a function of workpiece surface characteristics , and (b) contamination or scale on the surface does not affect tool life . this is the more common method of milling . the cutting process is smooth , provided that the cutter teeth are sharp . however , there may be a necessitating properclamping.In climb milling ,also called down milling ,cutting starts at the surface of the workpiece. Where the chip is at its thickest(figure 2.3(b)) . the advantage is that the downward component of the cutting forces holds the workpiece in place, particularly for slender parts. Because of the resulting high-impact forces when the teeth engage the workpiece , however ,this operation must have a rigid setup, and backlash must be eliminated in the table feed mechanism . climb milling is recommended, in general , for maximum cutter life in using computer numerical controlled (CNC) machine tools.2)types of milling machinei)column-and-knee type machinesused for general-purpose milling , column-and-knee type machines are the most common milling machines , the spindle on which the milling cutter is mounted may be horizontal for slab milling , or vertical for face and end milling , boring , and drilling operations . The basic components of these machines are as follows:A work table ,on which the workpiece is clamped using t-slots .the table moves longitudinally relative to the saddle .A saddle ,which supports the table and moves in the transverse direction.A knee , which supports the saddle and gives the table verticalmovement so that the depth of cut can be adjusted.An overarm in horizontal machines , which is adjustable to accommodate different arbor lengths .A head, which contains the spindle and cutter holders. In vertical machines , the head may be fixed or it can be vertically adjustable, and it can be swiveled in a vertical plane on the column for cutting tapered surfaces .ii)bed-type machinesin bed-type machines .the work table is mounted directly on the bed ,which replaces the knee and can move only longitudinally . these milling machines are not as versatile as other types ,but they have great stiffness and are used for high-production work . the spindles may be horizontal or veritical , and of duplex or triplex types—that is ,with two or three spindles ,respectively , for the simultaneous machining of two or three workpiece surfaces.iii)other types of milling machinesplaner-type milling machines, which are similar to bed-type machines , are equipped with several heads and cutters to mill various surfaces. They are used for heavy workpieces and are more efficient than planers when used for similar purposes. Rotary-table machines are similar to vertical milling machines and are equipped with one or more heads for face-milling operations.Various milling-machine components are being rapidly replaced by computer numerical control machines . these machine tools are versatile and capable of milling ,drilling ,boring , and tapping with repetitive accuracy.Reading material1,planting and shapingPlaning is a relatively simple cutting operation by which flat surfaces ,as well as various cross-sections with grooves and notches, are produced along the length of the workpiece. Planing is usually done on large workpieces-as large as 25mx 15m(75ftx 40ft).In a planer, the workpiece is mounted on a table that travels along a straight path. A horizontal cross-rail , which can be moved vertically along the ways in the column ,is equipped with one or more tool heads . the cutting tools are attached to the heads, and machining is done along a straight path. Because of the reciprocating motion of the workpiece, elapsed noncutting time during the return stroke is significant .Consequently , these operations are neither efficient nor economical , except for low-quantity production . the efficiency of the operation can be improved by equipping planers with tool holders and tools that cut in both directions of table travel .In order to prevent tool cutting edges from chipping when theyrub along a workpiece during the return stroke , tools are either tilted away or lifted mechanically or hydraulically . because of the length of the workpiece, it is essential to equip cutting tools with chip breakers . otherwise , the chips produced can be very long , interfering with the operation as well as becoming a safety hazard .Shaping is used to machine parts , which is much like planing , unless the parts are smaller . cutting by shaping is basically the same as by planing . in a horizontal shaper , the tool travels along a straight path , and the workpiece is stationary . the cutting tool is attached to the tool head , which is mounted on the ram .The ram has a reciprocating motion . in most machines , cutting is done during the forward movement of the ram (push cut ). But in others ,it is done during the return stroke of the ram (draw cut ). Vertical shapers (slotters) are used to machine notches, keyways , and dies. Because of low production rates , only special-purpose shapers , such as gear shapers , are in common use today .2,grinding operations and machinesGrinding is carried out with a variety of wheel-workpiece configurations . the selection of a grinding process for a particular application depends on part shape and size , ease of fixturing , and the production rate required .The basic types of grindings—surface, cylindrical , internal , andcenterless grinding—are described in this section. The relative movement of the wheel may be along the surface of the workpiece (traverse grinding , through feed grinding , cross-feeding ), or it may be radially into the workpiece (plunge grinding ) . surface gringers are comprised the largest percentage of grinders used in industry , followed by bench grinders (usually with two wheels at each end of the spindle ), cylindrical grinders , and tool and cutter grinders . the least common are internal grinders.Grinding machines are available for various workpiece geometries and sizes . modern grinding machines are computer controlled , with features such as automatic workpiece loading and unloading , clamping , cycling , gaging , dressing , and wheel shaping . grinders can also be equipped with probes and gages for determining the relative position of the wheel and workpiece surfaces as well as with tactile sensing features whereby diamond dressing-tool breakage , if any , can readily be detected during the dressing cycle .1)surface grindingsurface grinding involves grinding flat surfaces and is one of the most common grinding operations . typically , the workpiece is secured on a magnetic chuck attached to the work table of the grinder . nonmagnetic materials generally are held by vises , special fixtures, vacuum chucks ,or double-sided adhesive tapes.A straight wheel is mounted on the horizontal spindle of the grinder . traverse grinding occurs as the table reciprocates longitudinally and feeds laterally after each stroke . in plunge grinding , the wheel is moved radially into the workpiece ,as it is grindinga groove2). cylindrical grindingin cylindrical grinding ,also called center-type grinding, the external cylindrical surfaces and shoulders of the workpiece are ground . typical applications include crankshaft bearings , spindles , pins, bearing rings , and rolls for rolling mills .the rotating cylindrical workpiece reciproca t es laterally along its axis. In grinders used for large and long workpieces , the grinding wheel reciprocates ; called a roll grinder , it is capable of grinding rolls as large as 1.8m (72in) in diameter for rolling mills .the workpiece in cylindrical grinding is held between centers or in a chuck , or it is mounted on a faceplate in the headstock of the grinder . for straight cylindrical surfaces , the axes of rotation of the wheel and workpiece are parallel. Separate motors drive the wheel and workpiece at different speeds . long workpieces with two or more diameters are also ground on cylindrical grinders . cylindrical grinding can produce shapes (form grinding and plunge grinding) in which the wheel is dressed to the form to be ground.In universal grinders, both the workpiece and the wheel axes can be moved and swiveled around a horizontal plane , permitting the grinding of tapers and other shapes. These machines are equipped with computer controls , reducing labor and producing parts accurately and repetitively.3)internal grindingin internal grinding , a small wheel is used to grind the inside diameter of the part , such as to bushings and bearing races . the workpiece is held a rotating chuck and the wheel rotates at 30000 rpm or higher . internal profiles can also be ground with profile- dressed wheels that move radially into the workpiece . the headstock of internal grinders can be swiveled on a horizontal plane to grind tapered holes .4)centerless grindingcenterless grinding is a high-production process for continuously grinding cylindrical surfaces in which the workpiece is supported not by centers(hence the term “centerless”) or chucks , but by a blade . typical parts made by centerless grinding are roller bearings , piston pins , engine valves, camshafts, and similar components. This continuous production process requires little operator skill.In internal centerless grinding , the workpiece is supported between three rolls and is internally ground . typical applications are sleeve-shaped parts and rings.。
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Unit 4
1．Carbon steels (1) Low carbon steel containing from 0.05 to 0.15 percent carbon; this steel is also known as machine steel. (2) Medium carbon steel containing from 0.15 to 0.60 percent carbon. (3) High carbon steel containing from 0.6 to 1.50 percent carbon; this steel is sometimes called “tool steel”.
Unit 4
High carbon steels may be hardened by heating it to a certain temperature and then quickly cooling in water. The more carbon the steels contains and the quicker the cooling is, the harder it becomes. Because of its high strength and hardness this grade of steel may be used for tools and working parts of machines.
Unit 4
Unit 4
TEXT LEARN TO SPEAK NEW WORDS AND PHRASES NOTES EXERCISES READING MATERIAL PROFESSIONAL WORDS AND PHRASESຫໍສະໝຸດ Unit 4TEXT
Kinds of Steel
There are two general kinds of steels: carbon steel and alloy steel. Carbon steel contains only iron and carbon, while alloy steel contains some other “alloying elements” such as nickel, chromium, manganese, molybdenum, tungsten, vanadium, etc.
因为合金元素能提高钢的韧性、强度和硬度(在碳钢的 基础上)。有些合金元素能提高钢的耐蚀性，这种钢称做不 锈钢。
句中的“make”和“cause”均为及物动词，它们的宾语 分别为“them”和“steel”。宾语“them”的补足语是形容词 比较级“tougher, stronger, harder”等，而宾语“steel”的补足 语是不定式短语“to resist corrosion”。“stainless steels”是主 语“such steel”的补足语。
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Heat-resistant steel is made by adding some tungsten and molybdenum, while manganese increases the wear resistance of steel. Vanadium steels resist corrosion and can stand shocks and vibration.
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Some special alloy steels should be used for such parts because the alloying elements make them tougher, stronger, or harder than carbon steels. Some alloying elements cause steel to resist corrosion, and such steels are called stainless steels. Stainless steels contain a high percentage of chromium. Chromium also makes steel harder. Nickel is used in steel to increase strength and toughness. Some alloying elements (such as chromium and tungsten) make the grain of steel finer, thus increasing the hardness and strength of steel, because the finer the grain is, the stronger the steel becomes.
Tools made of high-speed steel containing tungsten, chromium, vanadium, and carbon, may do the work at much higher speeds than carbon tool steels.
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3．because the alloying elements make them tougher, stronger or harder than carbon steels. Some alloying elements cause steel to resist corrosion, and such steel are called stainless steels.
“the+比较级…(从句)+the+比较级…(主句)”结构表示 “越……越……”之意。
本句中的比较状语从句为“The more carbon the steel contain and the quicker the cooling is”，主句为“the harder it becomes”。句中第一个“the”和第二个“the”均为副词，分 别引出两个并列的比较状语从句。在这种情况下，第一个 “the”相当于“by so much”，第二个“the”相当于“by that much”。
LEARN TO SPEAK
Mr. Yang: Morning! Mr. Smith: Morning! Mr. Yang: Do you know about the kinds of steels? Mr. Smith: Yes, there are two general kinds of steels: carbon steel and alloy steel. Mr. Yang: Could you describe it in detail? Mr. Smith: OK. Carbon steel contains only iron and carbon, while alloy steel contains some other “alloying elements” such as nickel, chromium, etc.
“made of high-speed steel”作为分词短语，修饰 “Tools”，而“containing tungsten, chromium, chromium, vanadium and carbon”是另一分词短语作后置短语，修饰 “high-speed steel”。
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NOTES
1.high-speed steel also known as self-hardening steel 还有 通称为自硬钢的高速钢 “also known as self-hardening steel” 为分词短语作定语，修饰 “high-speed steel”。
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2．Alloy steels (1) Special alloy steel, such as nickel, chromium steel; (2) High-speed steel also known as self-hardening steel. Carbon steels are the most common steels used in industry. The properties of these steels depend only on the percentage of carbon they contain. Low carbon steels are very soft and can be used for bolts and for machine parts that do not need strength. Medium carbon steels are a better grade and stronger than low carbon steels. It is also more difficult to cut than low carbon steels.
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Mr. Yang: What can the carbon steel be used for? Mr. Smith: The carbon steel contains low, medium and high carbon steel, and can be used for bolts, tools and working parts of machines. Mr. Yang: Then, what can the alloy steel be used for? Mr. Smith: Alloy steel can be used for gears, bearings, springs and wires, etc. Because the alloying elements make them tougher, stronger, or harder than carbon steel. Mr. Yang: How about the tools which made of high speed steel? Mr. Smith: The tools made of high-speed steel of alloy steel containing tungsten, chromium, vanadium and carbon, may do the work at much higher speeds than carbon tool steels.