机械工程专业英语讲课教案

机械工程专业英语

Lesson1

1、the branch of scientific analysis, which deals with motions, time, and forces, is called mechanics and is made up of two parts, statics and dynamics. Statics deals with the analysis of stationary systems, i.e., those in which time is not a factor, and dynamics deals with systems, which change with time.

对运动时间和作用力作出科学分析的分支成为力学。他由静力学和动力学两部分组成。静力学对静止系统进行分析，即在其中不考虑时间这个引述，动力学对事件而变化的系统进行分析。

2、Any two such forces acting on a body constitute

a couple. The arm of the couple is the perpendicular distance between their lines of action, and the plane of the couple is the plane containing the two lines of action.

作用在一个刚体上的两个这样的的里构成一个力偶。力偶臂是这两个条作用线之间的垂直距离，力偶面是包含着两条作用线的平面。

3、Mechanics deal with two kinds of quantities: scalars and vectors. Scalar quantities are those with which a magnitude alone is associated. Examples of scalar quantities in mechanics are time, volume, density, speed, energy, and mass. Vector quantities, on the other hand, possess direction as well as magnitude. Examples of vectors are displacement, velocity, acceleration, force, moment, and momentum.

力学涉及两种类型的量，标量和矢量。标量是那些只有大小的量。在力学中标量的例子有时间、体积、密度、速率、、能量和质量。另一方面，矢量既有大小又有大小又有方向。矢量的例子有位移、速度、加速度、力、力矩、动量。Lesson2（此课后面没翻译，翻译的不太准确谅解）

1 、The turning of a part in a lathe is another example of several forces in action.（as shown in figure1）

车床车削是一些力在起作用的另一个例子。figure1(如图)。

2 、If this workpiece is held between the centers of the lathe, the centers exert a compressive force against the work.

如果这个工件在放在车床中心之间,中心车床对工作产生压力。

3、 Rotary motion is required to drill holes, turn parts in a lathe, mill surfaces, or drive a generator or fan belt.

扶轮运动需要去钻孔，在车床上转换两件,表面,或驱动发电机或风扇皮带

4 、Harmonic and Intermittent Motion（谐和运动和间歇运动）: Any simple vibration, such as the regular back, and forth movement of the end of a pendulum, is simple harmonic motion.

Lesson4

1 、Virtually all machines contain shafts. The most common shape for shafts is circular and the cross section can be either solid or hollow.

仅供学习与交流，如有侵权请联系网站删除谢谢2

实际上，几乎所有的机器中都装有轴。轴的最常见的形状是圆形，其截面可以是实心的，也可以是空心的（空心轴可以减轻重量）。有时也采用矩形轴，例如，螺丝起子的头部.套筒扳手和控制旋钮的杆。

2、 A shaft must have adequate torisonal strength to transmit torque and not be over stressed it must also be torsional stiff enough so that one mounted component does not deviate excessively from its original angular position relative to a second component mounted on the same shaft.

为了在传递扭矩时不发生过载，轴应该有适当的抗扭强度。轴还应该具有足够的抗扭强度，以使在同一轴上的两个传动零件之间的相对转角不会过大。

3 、Components such as gears and pulleys are mounted on shafts by means of key. The design of the key and the corresponding keyway in the shaft must be properly evaluated. For example, stress concentrations occur in shafts due to keyways, and the material removed to from the keyway further weakens the shaft.

齿轮和皮带轮等零件通过键连接在轴上。在键及轴上与之相对应的键槽的设计中，必须进行认真的计算。例如，轴上的键槽会引起应力集中，由于键槽的存在会使轴的横截面积减小，会进一步减弱轴的强度。

4、Another important aspect of shaft design is the method of directly connecting one shaft to another. Devices such as rigid and flexible couplings accomplish this.

轴的设计工作中的另一个重要方面是一根轴与另一根轴之间的直接连接方法。这是由刚性或者弹性联轴器来实现的。

Lesson5

1、The term shaft usually refers to a relatively long member of round cross section that rotates and transmits power. One or more members such as gears ,sprockers,pullys,and cams are usually attached to the shaft by means of pins,

keys,splines,snap rings,and other devices . These latter members are among the "associated parts" consedered in this text,as ate couplings and universal joints , which serve to connect the shaft to the source of power or load.

2、It is apparent that shafts can be subjected to various combinations of axial,bending,and torsional loads,and that these loads may be static or fluctuating.

3、Torsional defection can affect the accuracy of a cam or gear driven mechanism .Furthermore,the greater the flexibility -either lateral or torsional-the lower the corresponding critical speed.

4、A gear can be gripped axially between a shoulder on the shaft and a spacer ,with torque being transmitted through a keyways.

Lesson7

1、Fasteners are devices which permit one part to be joined to a second part and ,hence,they are involved in almost all designs . The acceptability of any product depends not only on the selected components , but also on the means by which they are fastened together. The principal purposes of fasteners are to provide the following design features;

仅供学习与交流，如有侵权请联系网站删除谢谢3

紧固件是将一个零件与另一个零件进行连接的零件。因此，几乎在所有的设计中都要用到紧固件。人们对于任何产品的满意程度不仅取决于其组成部件，还取决于其连接方式。

2、The importance of fasteners can be realized when referring ro any complex product,In the case of the automobile,there are literally thousands of parts which are fastened together to produce the total product.The failure or loosening of a single fastener could result in a simple nuisance such as a door rattle or in a serious situation such as a wheel coming off.

Such possibilities must be taken into account in the selection of the type of fatener for the specific application.

通过任何一个复杂的产品，都可以认识到紧固件在其中的重要性。以汽车为例，它是由数千个零件连接在一起而成为一辆车。一个紧固件的失效或松脱可能会带来像车门嘎嘎响这类小麻烦，也可能造成像车轮脱落这种严重的后果。因此，在为一个特定的用途选择紧固件时，应该考虑到上述各种可能性。

Lesson8

1、Threaded fasterners perform the function of locating ,clamgping ,adjusting ,and transmiting force from one machine member to another .They are thoroughly standardized and generally designed for use in mass production of machines.

2、 Matching external and internal threads so that they are may be assembled is the key to all thread fasteners.

3、 A particular SAE grade specilication can be met by a number of different steels, thus faster manufacturers have some latitude in selecting the materials best suited to their specific production faclities.

4、 For moderate loads and speedes the correct selection of a standard of the bearing on the basis of load rating will usually secure satisfactory performance. 对于中等载荷和转速，根据额定负

荷选择一个标准轴承，通常都可以保证其具有令

人满意的工作性能。

5、The deflection of less magnitude than that of the shafts or other components associated with the bearing .当载荷较大时，轴承零件的变形，尽管它通常小于轴和其它与轴承一起工作的零部件的变形，将会变得重要起来。

Lesson9

1、Where speeds are high special cooling arrangements become necessary which may increase frictional drag .

在转速高的场合需要有专门的冷却装置，而这

可能会增大摩擦阻力。

2、It is not surprising that ,owing to the high stresses involved,a predominant form of failure shouls be metal fatigue,and a good deal of work is currently in progress intended to improve the reliability of this type of bearing .

滚动轴承由于在工作中会产生高的应力，其主要失效形式是金属疲劳，这一点并不奇怪，目前

仅供学习与交流，如有侵权请联系网站删除谢谢4

正在进行大量的工作以求改进这种轴承的可靠性。

3、 The fit of the bearing races onto the shaft or onto the housing is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit.

轴承套圈与轴或轴承座的的配合非常重要，因为它们之间的配合不仅应该保证所需要的过盈量，而且也应该保证轴承的内部间隙。

4、The inner race is frequently located axially by abutting against a shoulder .Aradius at this point is essential for the avoidance of stress concentration and ball races rae providede with a radius or chamfer to allow space for this .

内圈通常是通过紧靠在轴肩上进行轴向定位的。轴肩出的圆弧半径主要是为了避免应力集中。在轴承内圈上加工出一个圆弧或者倒角，用来提供容纳轴肩处圆弧半径的空间。

5、Where life is not the determing factor in design ,it is usual to determine maximum loading by the amount to which a bearing will deflect under load .

在使用寿命不是设计中的决定因素的场合，通常根据轴承受载荷时产生的变形量来确定其最大载荷。

Lesson13

1、One of the primary considerations in designing any machine or structure is that the strength must be sufficiently greater that the stress to assure both safety and reliability. To assure that mechanical parts do not fail in service, it is necessary to learn why they sometimes do fail. Then we shall be able to relate the stresses with the strengths to achieve safety.

在设计任何机器或者结构时，所考虑的主要事项之一是其强度应该比它所承受的应力要大得多，以确保安全与可靠性。要保证机械零件在使用过程中不发生失效，就必须知道它们在某些时候会失效的原因，然后，才能将应力与强度联系起来，以确保其安全。

2、Ideally, in designing any machine element, the engineer should have at his disposal the results of a great many strength tests of the particular material chosen. These tests should have been made on specimens having the same heat treatment, surface roughness, and size as the element he proposes to design, and the tests should be made under exactly the same loading conditions as the part will experience in service.

设计任何机械零件的理想情况为，工程师可以利用大量的他所选用的这种材料的强度试验数据。这些试验应该在与所设计的零件有相同的热处理，表面粗糙度和尺寸大小的试件进行，而且试验应该在与零件使用过程中承受的载荷完全相同的情况下进行。

3、Most hardness-testing systems employ a standard load which is applied to a ball or pyramid in contact with the material to be tested. The hardness is then expressed as a function of the size of the resulting indentation. This means that hardness is an easy property to measure, because the

仅供学习与交流，如有侵权请联系网站删除谢谢5

test is nondestructive and test specimens are not required. Usually the test can be conducted directly on an actual machine element.

大多数硬度试验系统是将一个标准的载荷加在与被试验材料相接触的小球或者棱锥上。因此，硬度可以表示为所产生的压痕尺寸函数。这表明由于硬度是非破坏性试验，而且不需要专门的试件，因而硬度是一个容易测量的性能。通常可以直接在实际的机械零件上进行硬度试验。Lesson17

1、The first step in the manufacture of any product is design, which usually takes place in several distinct stages: (a) conceptual; (b) functional;

(c) production design. During the conceptual

design stage, the designer is concerned primarily with the functions the product is to fulfill.

制造任何产品的第一步工作都是设计。设计通常可以分为几个明确的阶段；（a）概念设计；b 功能设计 c 生产设计。在概念设计阶段，设计者着重考虑产品应该具有的功能。

2、Often a prototype or working model is made that can be tested to permit evaluation of the product as to function, reliability, appearance, serviceability, and so on.

通常要制造出样机或着实物模型，并对其进行实验，评价产品的功能、可靠性、外观和维修保养性等

3、As manufacturing progresses, it is inevitable that situations will arise that may require modifications of the materials being used. Experience may reveal that substitution of cheaper materials can be made.

在制造过程中，不可避免地会出现对使用中的材料做一些更改的情况。经验表明，可以采用某些便宜材料作为代替。

24/27课

Working drawings are the drawings from which a design is implemented. All principles of orthographic projection and techniques of graphics can be used to communicate the details of a project in working drawings. A detail drawing is a working drawing of a single part (or detail) within the set

of working drawings.

工作图是将设计变为实际产品所依据的图样。所有的正投影原理和绘图技术都可以用来在工作图中表达一个项目中的细节。零件图是在一整套工作图中关于一个零件（或细节）的工作图。Title Blocks In practice, title blocks usually contain the title or part name, drafter, date, scale, company, and sheet number. Other information, such as tolerances, checkers, and materials, also may be given. Any modifications or changes added after the first version to improve the design is shown in the revision

blocks.

标题栏在实践中，标题栏中通常包括标题或零件名称、制图员、日期、比例、公司和图号。另外，还可以包含公差、审核人员和材料等信息。在第一次制图之后，任何为了改进设计方案而作的修改和更正都应该在修改栏中标

明。

仅供学习与交流，如有侵权请联系网站删除谢谢6