机械专业英语董建国 第2章

1、Unit 2TEXT READING MATERIAL Unit 2Unit 2TEXTPrimary Motion and Feed Motion Broadly speaking，two kinds of relative motion must be provided by a machine toolthe primary motion and the feed motionCombination of these two motions will lead to a chip removal and the creation of machined surface with desi

2、red geometry. As a rule，the primary motion absorbs most of total power which is required to perform a machining operation. The feed motion may proceed by steps or continuously and absorb a small proportion of the total power Unit 2 Turning means machining a piece of rotating metal by pressing a hard

3、ened cutting tool against it. The work is given the primary motion while the tool is fed continuously. The process of planing and shaping is removing metal in a series of straight cuts. In planing, the work is given a linear motion while the tool remains motionless during the cutting stroke and is p

4、rovided with a lateral feeding movement during the return stroke. In the case of the shaper, the kinematic relationship between work and tool is reversed; however, the cutting action principle is the same. Drilling consists of rotating a cutting tool and advancing the tool along its own axis into a

5、stationary work-piece to produce a round hole. Of the two functions，advancing the tool along its axis is the major consideration in the design of drilling machines. Rotating the drill is, by comparison, a simple matter.Unit 2Fig. 2-1 Primary motion and feed motion Unit 2 LEARN TO SPEAK John：How do y

6、ou do! My name is John. Miss Li:How do you do! John：Are there any vacancies in your factory? Miss Li:Yes. We need some new workers. What subject was your major? John：I majored in mechanical manufacturing, and I think I am good at operating milling machine.Unit 2Miss Li:What sort of job do you like t

7、o do?John：I would like to be milling worker. I think I can do my best to it. Miss Li:Great! What time can you start to work?John：Anytime.Miss Li:Very nice. How much do you expect in salary?John：800 yuan.Miss Li:OK! Please fill in this form. If anything turns, Ill contact with you.John：Thank you!Miss

8、 Li:Youre welcome. Unit 2NEW WORDS AND EXPRESSIONSprimary 5praImErI adj. 第一位的，初级的broad brC:d adj. 宽的broadly adv. 概括地，大致地removal rI5mu:v(E)l n. 移动，切除geometry dVI5RmItrI n. 几何形状，几何学absorb Eb5sC:b vt. 吸收，吸引proceed prE5si:d vi. 进行，发生continuous kEn5tInjJEs adj. 连续的，持续的continuously adv. 连续不断地Unit 2proport

9、ion prE5pC:F(E)n n. 比例，部分linear 5lInIE(r) adj. 直线的，线性的motionless 5mEJF(E)nlIs adj. 不动的，静止的lateral 5lAtEr(E)l adj. 横(向)的return rI5tE:n v.&n. 返回，退回kinematic kB:nI5mAtIk adj. 运动学(上)的relationship rI5leIFEnFIp n. 关系reverse rI5vE:s v.&n. 相反，背面，倒退 Unit 2adj. 相反的reversely adv. 相反principle 5prInsIp(E)l n. 原则

10、，原理advance Ed5vB:ns; (?) Ed5vAnsv. 前进，推进axis 5AksIs n. 轴axes 5AksIz n. 轴(复数)round raJnd adj. 圆的prep. 围着adv. 围绕着Unit 2 consideration kEnsIdE5reIF(E)n n. 考虑comparison kEm5pArIs(E)n n. 比较matter 5mAtE(r) n. 事件，物质mechanical mI5kAnIk(E)l adj. 机械的manufacturing 9mAnjJ5fAktFErIN n. 制造业vacancy 5veIkEnsI n. 空缺

11、Unit 2 primary motion 主运动broadly speaking 概括地讲lead to 导致as a rule 通常，照例by steps 逐步地a small proportion of 小部分linear motion 线性运动lateral feeding movement 横向进给运动return stoke 返回行程take into consideration 对加以考虑，考虑到by comparison 比较起来Unit 2NOTES 1. Broadly speaking，two kinds of relative motion must be provid

12、ed by a machine toolthe primary motion and the feed motion概括地讲，机床必须提供两种相对运动主运动与进给运动。 “Broadly speaking”是插入语，这里可译为“一般讲”。破折号后面的内容“the primary motion and the feed motion”实际上是解释“two kinds of relative motion”，不要认为破折号在“a machine tool”后面，就误以为“the primary motion and the feed motion”是解释“a machine tool”的。在英语中

13、，很多场合使用被动语态，宾语放在了前面，而主语放在了后面，造成了中心词与解释中心词的内容从形式上看被分开了，因而在翻译时要特别引起注意。 Unit 2 2. As a rule，the primary motion absorbs most of total power which is required to perform a machining operation.通常，主运动要消耗切削加工所需要的总功率中的大部分。 “as a rule”作为一个整体，其含义为“通常”。“which”引导的是定语从句，用来进一步解释“total power”是用来干什么的。 Unit 2 3. The

14、work is given the primary motion while the tool is fed continuously. 工件做主运动，而刀具则做连续进给运动。 “be given” (被给)常可译成“得到”、“获得”。例如： I am given a book. 我得到一本书。 In turning, the work is given the primary motion. 车削时，工件获得主运动。 Unit 2 4. Of the two functions，advancing the tool along its axis is the major considerat

15、ion in the design of drilling machines. 在这两种功用中，使钻头沿自身的轴线进给是设计钻床时主要考虑的问题。 “Of” 放在句首表示“在中”，例如： Of all machine tools, the lathe is the most common one. 在所有的机床中，车床是最普通的一种。 Of all metals, steel is the most widely used in engineering. 在所有的金属中，钢在工程上用得最普遍。Unit 2 有时把句子从英文翻译成中文时要根据上下文的意思适当地加词，以使句子读起来通俗易懂。本句在

16、翻译时，在两种功用的前面加上了一个定语“加工出一个孔的”，虽然本句中没有对应的英文，但从上一句讨论的钻削中，我们就可以知道是在讲加工一个孔。 Unit 2EXERCISES 1Discuss the following questions in English: (1) What is the primary motion? (2) What is the feed motion? (3) What is turning? (4) What is drilling?Unit 2 2Use English for replacing Chinese or use Chinese for repl

17、acing English. (1) 相对运动 (2) 加工表面 (3) 机械制造 (4) Desired geometry (5) A machining operation (6) Rotating a cutting toolUnit 2READING MATERIALPower in The Workshop The processes of cutting metal generally require some power so that the application of power to workshop processes is importantEnergy is req

18、uired in various forms by machine tools，for example，reciprocating motion to a planer table，longitudinal feed to a lathe carriage, rotational motion to a drill，etc., but it is nearly always supplied to the machine in the form of rotational energy at the pulleyOne of the functions of the machine is to

19、 convert the rotational energy into the required formEnergy is supplied to most of our workshops in the form of electricity，and it is converted to rotational energy by means of an electric motor. Unit 2 Early machine tools were driven by a reciprocating steam engine through a system of pulleys, belt

20、s，and clutchesUsually，a single steam engine provided the power for several machine tools in the workshopLater, a single electric motor replaced the steam engine to drive a group of machine toolsIn modern workshops，most of the machine tools are provided with individual motor driveEach machine has its own el