机械工程专业外语试卷

机械工程专业外语试卷
《机械工程专业英语》测验题(15-17)
一、将下列词组译成汉语
1. kinematic chain（运动链）
2. skeleton diagram（草图，示意图，简图）
3. Gear system/Cam system（齿轮传动系统/凸轮系统）
4. uniform motion/nonuniform motion（匀速运动/非匀速运动）
5. nonlinear motion（非线性运动）
6. kinematic analysis（运动分析）
7. schematic diagram（运动简图）
8. textile machinery（纺织机械）
9. Kinematic design/ kinematic syntheses （运动设计/运动合成）
10. machine design（机械设计）
11. Gear trains/ Cam mechanisms（轮系，齿轮传动链/凸轮机构）
12. dynamic force/inertia force/ static
force（动力/惯性力/静力）
13. relative velocity/ absolute velocity （相对速度/绝对速度）
14. angular acceleration/ tangential acceleration/ centripetal acceleration/ velocity vector（角加速度/切向
加速度/向心加速度/速度矢量）
15. binary link/ ternary link（二杆组/三杆组）
二、将下列短语译成汉语
1. Plane and spatial linkages（平面和空间连杆）
2. constrained kinematic chain/unconstrained kinematic chain（约束运动链/非约束运动链）
3. closed-loop linkage（闭环运动链）
4. four-bar linkage（四连杆机构）
5. slider-crank (or crank and slider) mechanism（曲柄滑块机构）
6. internal combustion engine（内燃机）
7. the kinematic analysis of mechanisms（机构运动分析）
8. degree of freedom of the mechanism（机构自由度）
9. kinematic analysis process /kinematic synthesis process（运动分析步骤/运动合成步骤）
10. input angular velocity（输入角速度）
11. input angular acceleration（输入角加速度）
12. automatic packaging machinery（自动包装机）
13. cam-contour dimensions/cam-follower diameters（凸轮轮廓尺寸/凸轮从动件直径）14. mechanical analog computer（机构模拟计算机）
15. dead-center position（死点位置）
16. crank-rocker linkage/double-rocker
linkage/double-crank (drag-link) linkage （曲柄摇杆机构/双摇杆机
构/双曲柄机构）
17. maximum force component/ resulting output force or torque（最大的力量组成/输出的最大力或力矩）
18. output motion variables/input motion variable（输出运动变量/输入运动变量）
19. absolute angular positions（绝对角位置）
20. velocity polygon method（速度的多边形的方法）
21. instantaneous center method/instant center method（瞬心法/即时瞬心法）
22. inertia-force analysis of mechanisms and machines（机构和机器的惯性力分析）23. one and the same coordinate system /inertia frame of reference（惯性参考系）24. systematic design of mechanisms（机械设计的系统）
25. cam-contour dimensions/cam-follower diameters（凸轮轮廓尺寸/凸轮从动件直径）三、将下列单词译成汉语
1
1. Mechanism（机械，机构，机构学）
2. configuration（外形，构造，结构）
3. displacement（位移）
4. velocity（速度）
5. acceleration（加速度）
6. gear（齿轮）
7. sprocket（链轮）
8. pulley（带轮）
9. kinematician /dynamics（运动/动力学，力学）10. kinematician（运动）
四．翻译下列句子
1. The simplest closed-loop linkage is the four-bar linkage, which has three moving links (plus one fixed link) and four pin joints.（最简单的封闭式的连杆机构就是四杆机构，四杆机构有三个运动构件（加上一个固定构件）并且有四个销轴。

）
2. Although the four-bar linkage and
slider-crank mechanism are very useful and found in thousands of applications, we can see that these linkages have limited performance level.( 虽然四杆机构和曲柄滑块机构是非常有用而且在成千上万的应用中都可找到。

但是我们还看到，这些连杆机构其性能水平的发挥已经受到限制。

)
3. The process of drawing kinematic diagrams and determining degrees of freedom of mechanisms are the
first steps in both the kinematic analysis and synthesis process.（画运动图和确定机构自由度的过程，就是运动分析和综合过程的第一个阶段。

）
4. The ability to visualize relative motion, to reason why a mechanism is designed the way it is, and the ability to improve on a particular design are marks of a successful kinematician.（设想相对运动的能力，能推想出之所以这样设计一个机构的原因和对一个具体设计进行改进的能力是一个成功的机构学家
的标志。

）
5. Kinematic inversion is the process of fixing different links of a chain to create different mechanisms.（这个过程的动态反演是固定的,不同的连接创造出不同的机制。

）
6.There are three customary tasks for kinematic synthesis: function generation, path generation and motion generation.（对于运功的综合，惯例上有三个任务:函数的生成、轨迹生成和运动生成。

）
五．翻译下列短文
1.A kinematic chain is a system of links, that is, rigid bodies, which are either jointed together or are in contact with one another in a manner that permits them to move relative to one another. If one of the links is fixed and the movement of any other link to a new position will cause each of the other links to move to definite predictable position, the system is a constrained kinematic chain. If one of the links is held
fixed and the movement of any other link to a new position will not cause each of the other links to move to a definite predictable position, then the system is an unconstrained kinematic chain.
（运动链是一个构件系统装置即若干个刚体，它们或者彼此铰接或者互相接触，方式上是允许它们彼此间产生相对运动。

如果构件中的某一构件被固定而使任何其他一个构件运动到新的位置将会引起其他各个构件也运动到确定的预期的位置上的话，该系统装置就是一个可约束的运动链。

如果构件中的某一构件仍保持固定而使任一运动到达一新的位置而不会使其他各个构件运动到一个确定的预期的位置上的话，则该系统装置是一个非约束运动链。

）
2. A mechanism or linkage is a constrained kinematic chain, and is a mechanical device that has the
purpose of transferring motion and/or force from a source to an output. A linkage consists of links (or bars), 2
generally considered rigid, which are connected by joints, such as pin (or revolute) or prismatic joints, to form open or closed chains (or loops). Such kinematic chains, with at least one link fixed, become (1) mechanisms if at least two other links remain mobility, or (2) structures if no mobility remains. In other words, a mechanism permits relative motion between its "rigid links"; a structure does not. Since linkages make simple mechanisms and can be designed to perform complex tasks, such as nonlinear motion and force transmission, they will receive much attention in mechanism study.
（机构或连杆构件是一个可约束的传动链而且是一个从输入到输出以传递运动和（或）力为目的的机械装置。

连杆机构是由通常被认为是刚体构件或杆组成的，它们是以销轴铰接的，例如用柱销（圆形的）或棱柱体销轴铰接，以便成形开式或闭式（回环式）的运动链。

这样的运动链在至少有一个构件被固定的条件下：（1）如果至少
有两个构件能保持运动，就变为机构，（2）如果没有一个构件能够运动，则就成为结构。

换句话说，机构是允许其“刚性构件”之间相对运动，而结构则不能。

由于连杆机构做成一简单机构而且能设定实现复杂的任务，例如非线性运动和力的传递运动。

它们在机构学研究中将受到更多的关注。

）
3. The four-bar linkage may take form of a so-called crank-rocker or a double-rocker or a double-crank (drag-link) linkage, depending on the range of motion of the two links connected to the ground link. The input crank of a crank-rocker type can rotate continuously through 360, while the output link just "rocks" (or oscillates). As a particular case, in a parallelogram linkage, where the length of the input link equals that of the output link and the lengths of the coupler and the ground link are also the same, both the input and output link may rotate entirely around or switch into a crossed configuration called an
antiparallelogram linkage. [1] Grashof's criteria states that the sum of the shortest and longest links of a planar four-bar linkage cannot be greater than the sum of the remaining two links if there is to be continuous relative rotation between any two links.（四杆机构可具有一种称作曲柄摇杆机构的形式，一种双摇杆机构，一种双曲柄（拉杆）机构，致于称作哪一种形式的机构，取决于跟机架（固定构件）相连接的两杆的运动范围。

曲柄摇杆机构的输入构件，曲柄可旋转通过360°并连续转动，而输出构件仅仅作摇动（即摇摆的杆件）。

作为一个特例，在平行四杆机构中，输入杆的长度等于输出杆的长度，连接杆的长度和固定杆（机架）的长度，也是相等的。

其输入和输出都可以作整周转动或者转换成称作反平行四边形机构的交叉结构。

格拉肖夫准则（定理）表明：如果四杆机构中，任意两杆之间能作连续相对转动，那么，其最长杆长度与最短杆长度之和就小于或等于其余两杆长度之和。

）4. Besides having knowledge of the extent of the rotations of the links, it would be
useful to have a
measure of how well a mechanism might "run" before actually building it. Hartenberg mentions that "run" is a term that means effectiveness with which motion is imparted to the output link; it implies smooth operation, in which a maximum force component is available to produce a force or torque in an output
member. Although the resulting output force or torque is not only a function of the geometry of the linkage, but is generally the result of dynamic or inertia force, which are often several times as large as the static force. For the analysis of low-speed operations or for an easily obtainable index of how any mechanism might run, the concept of the transmission angle is extremely useful. During the motion of a mechanism, the transmission angle changes in value. A transmission angle of 0 degree may occur at
a specific position, on which the output link will not move regardless of how large a force is applied to the input link. In fact, due to friction in the joints, the general rule of thumb, is to design mechanisms with transmission angle of larger than a specified value. Matrix-based definitions have been developed which measure the ability of a linkage to transmit motion. The value of a determinant (which contains derivatives of output motion variables with respect to an input motion variable for a given linkage geometry[2] ) is a measure of the movability of the linkage in a particular position.
3
（除了具备关于构件回转范围的知识之外，还要具备如何使机构在制造之前就能“运转”的良好措施，那将是很有用的。

哈登伯格（Hartenberg）说到：“运转”是一个术语，其意义是传给输出构件的运动的有效性。

它意味着运转平稳，其中
能在输出构件中产生一个力或扭矩的最大分力是有效的。

虽然最终的输出力或扭矩不仅是连杆几何图形的函数，而且一般也是动力或惯性力的结果，那常常是大到如静态力的几倍。

为了分析低速运转或为了易于获得如何能使任一机构“运转”的指数，传动角的概念是非常有用的。

在机构运动期间，传动角的值在改变。

传动角0°可发生在特殊位置上。

在此特殊位置上输出杆将不运动而与施加到输入杆上的力多大无关。

事实上，由于运动副摩擦的影响，一般根据实际经验，用比规定值大的传动角去设计机构。

衡量连杆机构传递运动能力的矩阵基础的定义已经研究出来。

一个决定性因素的值（它含有对于某个给定机构图形，位置的输出运动变量对输入变量的导数）是该连杆机构在具体位置中的可动性的一个尺度。

）
5. Mechanisms form the basic geometrical elements of many mechanical devices including automatic packaging machinery, typewriters, mechanical toys, textile machinery, and others. A mechanism typically is designed to create a desired
motion of a rigid body relative to a reference member. Kinematic design, or kinematic syntheses, of mechanisms often is the first step in the design of a complete machine. When forces are considered, the additional problems of dynamics, bearing loads, stresses, lubrication, and the like are introduced, and the larger problem becomes one of machine design.
（机构是形成许多机械装置的基本几何结构单元，这些机械装置包括自动包装机、打印机、机械玩具、纺织机械和其他机械等。

典型的机构要设计成使刚性构件相对基准构件产生所希望的运动。

机构的运动设计即运动的综合，第一步常常是先设计整部机器。

当考虑受力时，要提出动力学方面的问题，轴承的荷载、应力、润滑等类似的问题，而较大的问题是机器结构问题。

）6. A kinematician defined kinematics as "the study of the motion of mechanisms and methods of creating them." The first part of this definition deals with kinematic
analysis. Given a certain mechanism, the motion
characteristics of its components will be determined by kinematic analysis. The statement of the tasks of analysis contains all principal dimensions of the mechanism, the interconnections of its links, and the specification of the input motion or method of actuation. The objective is to find the displacements, velocities, accelerations, shock or jerk (second acceleration), and perhaps higher accelerations of the various members, as well as the paths described and motions performed by certain elements. In short, in kinematic analysis we determine the performance of a given mechanism. The second part of definition may be paraphrased in two ways:
（运动学家把运动学定义为“研究机构的运动和创建机构的方法”。

这个定义的第一部分就涉及运动学分析。

已知一个机构，其构成的运动特性
将由运动学分析来确定。

叙述运动分析的任务包含机构的主要尺寸、构件间的相互连结和输入运动的技术特性或驱动方法。

目的是要找出位移、速度、加速度、冲击或跳动（二次加速度），和可能发生的各构件的高阶加速度以及所描述径迹和由某些构件来实现的运动。

定义的第二部分可用以下两方面来解释：）
(1) The study of methods of creating a given motion by means of mechanisms
(2) The study of methods of creating mechanisms having a given motion.
In either version, the motion is given and the mechanism is to be found. This is the essence of kinematic synthesis. Thus kinematic synthesis deals with the systematic design of mechanisms for a given performance. The area of synthesis may be grouped into two categories.
1．研究借助机构来产生给定运动的方法
42．研究建造能产生给定运动机构的方法
在两个方案中，运动是给定的而机构是创建的。

这就是运动综合的本质。

这样运动综合涉及到为给定性能的机构的系统设计。

运动综合方面又可归结为以下两类
(1) Type synthesis. Given the required performance, what type of mechanism will be suitable? (Gear trains? Linkages? Cam mechanisms?) Also, how many links should the mechanism have? How many degrees of freedom are required? What configuration is desirable? And so on. Deliberations involving the number of links and degrees of freedom are often referred to as the province of a subcategory of type synthesis called number synthesis.
(2) Dimensional synthesis. The second major category of kinematic synthesis is best defined by way of its objective : Dimensional synthesis seeks to determine the significant dimensions and the starting position of a mechanism of preconceived type
for a specified task and prescribed performance.
1．类型综合。

规定所要求的性能，怎样一种类型的机构才是合适的？（齿轮系，连杆机构？还是凸轮机构？）而机构应具有多少构件？需要多少个自由度？怎样的轮廓结构才是所希望的？等等。

关于杆件数目和自由度的考虑通常被认为是类型综合中被称作为数量综合的一个分支领域。

2．尺寸综合。

运动综合的第二个主要类型是通过目标法来确定的最佳方法。

尺寸综合试图确定机构的重要尺寸和起动位置，该机构是为着实现规定的任务和预期的性能而事先设想的。

of their contacting profiles must be such that the common normal passes through a fixed point on the line of the centers. 齿轮是借助于轮齿成功啮合来传递运动的机器零件。

齿轮从一根回转轴到另一回转轴传递运动或传递运动到一传动齿条。

多数应用中都以恒定角速比（或常定扭矩比）而存在。

恒定角速比应用中必定是轴向传动。

在各种各样有用的齿轮类
型基础上，输入轴和输出轴需要在一直线上或需要互相平行都不受什么限制。

由于使用非圆齿轮，非线性角速比也是很有用的。

为了保持恒定的角速度，各个齿轮齿廓必须服从齿轮啮合的基本规律：为了一对齿能传递恒定角速比，他们接触齿廓的形状必须是要这样：公法线通过两齿轮中心连线上的固定点。

《机械工程专业英语》测验题(18-22)
四、将下列词组译成汉语
16. the base circle（基圆）17. the pitch curve （啮合曲线）18. the contact force（接触力）19. the intermittent motion（间歇运动）20. the common normal（公法线）
21. the conjugate profiles（共轭齿廓）22. the cycloidal profiles （摆线齿形）
23. the involute profiles（渐开线齿形）24. the spur gear（直齿轮）
25. the herringbone gears（双螺旋齿轮）26. the face gear（端面齿轮）
27. the radial distance（径向距离）28. the addendum circle（齿顶圆）
29. The tooth thickness（齿厚）30. the tooth space（齿间隙）
31. the cap screws（螺钉）32. the setscrews （固定螺丝钉）
33. the engineering graphics（工程力学）34. mechanical design（机械设计）
35. the installation techniques（安装技术）
36. the bolted joint（螺栓连接）
37. the hardened washers（强化垫圈）38. the fatigue resistance（抗疲劳强度）
39. the modulus of elasticity（弹性模量） 40. the antifriction bearing（减摩轴承）
41. the rolling bearing（滚动轴承） 42. the rolling contact （滚动接触）
43. the sliding contact（滑动触电） 44. the corrosion resistance（抗腐蚀性）
45. the machining tolerances（加工公差）
46. the fatigue loading（疲劳载荷）
47. the radial loads（径向负荷） 48. the thrust loads逆负荷
49. the ball bearing球轴承 50. the roller bearing滚子轴承
51. the single-row bearings单沟轴承 52. the double-row bearing双沟轴承
53. the needle bearing滚针轴承 54. the bearing life轴承寿命
55. The rating life额定寿命 56. the axis of rotation旋转轴
57. The helix angle螺旋角58. a right-hand helix 右旋
59. a left-hand helix左旋60. an involute helicoids螺旋面
61. an involute curve渐开线 62. the shaft centerlines轴中心线
63. worm gear蜗轮 64. the hypoid gear 准双曲面齿轮
65. right angle直角 66. worm gearing蜗杆传动
67. the lead angle导角 68. shaft angle 轴线角度
69. bending load弯曲载荷 70. tension load 张力负荷
71. compression load压缩负载72. torsional load扭转负荷
73. the bending moment弯矩74. the bending stress弯曲应力
75. the shot peening喷丸法
76. the actuating force工作力 77. the coefficient of friction摩擦系数
78. An electromagnetic coil电磁线圈 79. the magnetic circuit磁路
五、将下列短语译成汉语
26. disk or plate translating (two-dimensional or planar) 盘形传动凸轮（两维的，即平面的）
27. cylindrical (three-dimensional or spatial) cams圆柱形凸轮（三维的，即空间的）机构
28. a radial (in-line) translating roller follower一个对心直动滚子从动件
29. a constant angular velocity ratio旋转角速度的比例
30. a constant torque ratio一个恒转矩比
31. Nonlinear angular velocity ratios非线性角速度比率
32. the parallel helical gear平行斜齿轮
33. the crossed helical gear交叉斜齿轮
34. the straight bevel gear直锥齿轮
35. the spiral bevel gear弧齿锥齿轮
36. the skew bevel gear大角度斜交锥齿轮
37. the hexagon head screws六角头螺钉
38. the fillister head screws槽头螺钉
39. the flat head screws 平头螺钉
40. the hexagon socket head screws内六角沉头螺钉。

41. the external tensile load外部拉伸载荷
42. the external shear load外部剪切负荷
43. The single-row deep-groove bearing单列深沟轴承
44. The angular-contact bearing角接触轴承
45. the self-aligning bearings自动调心轴承
46. the straight roller bearings直滚子轴承
47. the spherical-roller thrust bearing球形辊止推轴承
48. the tapered roller bearings圆锥滚子轴承
49. the condition of statical equilibrium 浅析条件下平衡
50. the positive-contact clutches强制接触离合器
51. the overload-release clutches超载释放保护离合器
52. the overrunning clutches超越离合器
53. the magnetic fluid clutches磁流变离合器
六、将下列单词译成汉语
11. cam凸轮 12. camshaft凸轮轴 13. accuracy精度
14. dependability可靠性 15. pulley滑轮16. flywheel飞轮 17. crank曲柄 18. sprocket链轮
19. axle心轴 20. spindle主轴 21. clutche离合器
7
22. brake制动
四．翻译下列句子
1．Although a cam and follower may be designed for motion, path, or function
generation, the majority of applications utilize the cam and follower for function generation.
虽然可以把凸轮和它的从动件设计为用于运动变换，路径变换或者函数变换，但大多数用途是利用凸轮和它的从动件做函数变换。

2. In the case of a disk cam with a radial (in-line) translating roller follower the smallest circle that can be drawn tangent to the cam surface and concentric with the camshaft is the base circle. 对于一个对心直动滚子从动件盘形凸轮，可画出的与凸轮表面相切且与轮轴同心的最小圆是基圆
译文 P40 [1]
3. Numerous applications in automatic machinery require intermittent motion. A typical example will call for a rise-dwell-return and perhaps another dwell period of a specified number of degrees each, together with a required follower displacement measured in centimeters or
degrees.
在自动化机械中的许多应用需要间歇运动。

一个典型的例子将要求一个含有上升一停歇一返回和可能另一个停歇的周期，每阶段经过一个指定的角度，伴随着一个所要求的从动件的位移，这个位移以厘米或度来度量。

译文 P40 [2]
4．Any two mating tooth profiles that satisfy the fundamental law of gearing are called conjugate profiles.
任何满足齿轮传动基本定律的一对相互啮合齿廓称之为共轭齿廓。

5. Although there are many tooth shapes possible in which a mating tooth could be designed to satisfy the fundamental law, only two are in general use: the cycloidal and involute profiles.
虽然可以设计出有很多齿廓来满足传动装置的基本定律，但通常所使用的只有两种：即摆线齿廓和渐开线齿廓。

6. Typical methods of fastening and joining parts include the use of such items as bolts, nuts, cap screws, setscrews, rivets, locking devices and keys.
紧固和联结零部件的典型方法包含使用这些零件：螺栓，螺母，有头螺钉、定位螺钉，铆钉，锁紧装置和键。

7. Methods of joining parts are extremely important in the engineering of a quality design, and it is necessary to have a thorough understanding of the performance of fasteners and joints under all conditions of use and design.
在质量设计工程中，联结零部件的方法非常重要，因此，彻底了解紧固零件和联结零件在所有使用和设计条件下的性能是非常必要的。

8. When a connection is desired which can be disassembled without destructing the parts assembled and which is strong enough to resist both external tensile load and shear load, or a combination of these, then the
simple bolted joint using hardened washers is a good solution.
当想要一个可以被拆开又不破坏被联接零件的联接时，而且这个联接又要有足够的强度以承受外拉力和剪力或这两种力的结合，使用淬火垫圈的简单螺栓联结是一个很好的方法。

译文 P43 [2]
9. The problem of the specialist in mechanical design is not how to design a rolling bearing but, rather, how to select one.
在机械设计中，专家所面临的问题，不是如何设计轴承，而是如何挑选轴承。

10. The term antifriction bearing is used to describe that class of bearing in which the main load is transferred through elements in rolling contact rather than in sliding contact.
减摩轴承这个词被用于描述这样一类轴承，其主要载荷是通过滚动接触而不是滑动接触的元件
传递的．
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11. It is this gradual engagement of the teeth and the smooth transfer of load from one tooth to another, which give helical gears the ability to transmit heavy loads at high speeds．
正是螺旋齿轮，从一个齿到另一个齿的逐渐啮合和载荷的平稳传递，给了螺旋齿轮在高速下传递重载荷的能力．
12. A shaft is a rotating or stationary member, usually of circular cross section, having mounted upon it such elements as gears, pulleys, flywheels, cranks, sprockets, and other power-transmission elements.
轴是一个固定或转动的零件，通常是圆截面的，在它上面安装了如齿轮，带轮，飞轮，曲柄，链轮等零件和其他动力传递零件．
13. Roughing, for which the metal removal
rate, and consequently the cutting force, is high, but the required dimensional accuracy relatively low.
粗加工，通常金属切削率和切削力高，但所要求的尺寸精度相对低。

14. Machines using basically the single-point cutting tools include: (1) engine lathes, (2) turret lathes,
(3) tracing and duplicating lathes, (4) single-spindle automatic lathes, (5) multi-spindle automatic lathes, (6) shapers and planers, (7) boring machines.
使用单刃切削刀具的机床主要包括：(1)普通车床，(2)六角车床，(3)仿形车床，(4)单轴自动车床，(5)多轴自动车床，(6)牛头刨床和龙门刨床, (7)镗床。

15. Upright drilling machines or drill presses are available in a variety of sizes and types, and are equipped with a sufficient range of spindle speeds and
automatic feeds to fit the needs of most industries.
立式钻床或钻孔压力机，具有各种各样的尺寸和类型，为了适合大多数工业的需求，这些机床都装配有充足的轴速范围和自动进给量。

16. Chemical milling is controlled etching process using strong alkaline or acid etchants. Aluminum, titanium, magnesium, and steel are the principal metals processed by this method.
化学蚀刻，通过使用强碱或强酸蚀刻剂来控制蚀刻过程，铝，钛，镁和钢是用这种方法处理的主要金属。

17. Antifriction bearings are used in a great variety of products, toys, household products, refrigerators, roller stakes, garage doors, trucks, industrial machinery, dental equipments and guided missiles, for example.
减摩轴承使用在各种各样的产品中，例如：玩具，
家用产品，电冰箱，轧辊座，汽车门，卡车，工业机械，牙医设备和导弹等等。

18. The important difference between the two is that area contact exists between the teeth of double-enveloping gears while only line contact between those of single-enveloping gears.
这两者之间的重要区别是：在双包围蜗轮组的轮齿间有面接触，而在单包围蜗轮组的轮齿间只有线接触。

19. Although positive clutches are not used to the extent of the frictional-contact type, they do have important applications [3] where synchronous operation is required. 虽然强制接触离合器不像摩擦离合器用得那么广泛，但在需要同步操作时，它们确实有着非常重要的应用。

20. Finishing, for which the metal removal rate, and consequently the cutting force, is low, but the required dimensional accuracy
and surface finish relatively high.
精加工，通常金属切削率和切削力低，但所要求的尺寸精度和表面光洁度相对高。

21. Machines using multipoint cutting tools include: (1) drilling machines, (2) milling machines, (3) broaching machines, (4) sawing machines, (5) gear-cutting machines. 使用多刃切削刀具的机床包括：(1)钻床，(2)铣床，(3)拉床，(4)锯床，(5)齿轮切削机床。

22. Tracer milling is characterized by coordinated or synchronized movements of either the paths of the cutter and tracing elements, or the paths of the workpiece and model.
仿形铣床的特点是刀具和跟踪元件的轨迹运动的协调或同步，或者是工件和模型的轨迹运动的协调或
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同步。

23. The problem of the specialist in mechanical design is not how to design a rolling bearing but, rather, how to select one.
在机械设计中，专家所面临的问题，不是如何设计轴承，而是如何挑选轴承。

24. The ultrasonic machining process is applied to both conducting and non-conducting material, and relies entirely upon abrasive action for metal removal.
超声波加工工艺既应用于导体材料，也用于非导体材料，并且完全依赖于磨损作用进行金属切削。

五．翻译下列短文
1. Numerous applications in automatic machinery require intermittent motion. A typical example will call for a rise-dwell-return and perhaps another dwell period of a specified number of degrees each,
together with a required follower displacement measured in centimeters or degrees. [2] The designer's job is to lay out the cam accordingly. The first decision to be made is to choose the cam follower type. The specified application may dictate the combination of the cam and follower. Some factors that should enter into the decision are: geometric considerations, dynamic considerations, environmental considerations and economic matters. Once a type of cam and follower pair has been selected, the follower motion must be chosen. Therefore, the velocity, acceleration, and in some cases further derivatives of the displacement of the follower are of great importance.
在自动化机械中的许多应用需要间歇运动。

一个典型的例子将要求一个含有上升一停歇一返回和可能另一个停歇的周期，每阶段经过一个指定的角度，伴随着一个所要求的从动件的位移，这个位移以厘米或度来度量。

设计者的工作就是相
应地设计出该凸轮。

首先要做的决策就是要选择凸轮从动件的类型。

规定的应用可能要求凸轮和从动件相结合。

转化为决策的某些因素有：几何形状条件，动力条件，环境条件和经济因素。

一旦凸轮与从动件运动副类型被选定，则从动件运动就必定选定。

因此，速度、加速度和在某些情况下，从动件位移的进一步的方案实属极端重要。

2. Gears are machine elements that transmit motion by means of successively engaging teeth. Gears transmit motion from one rotating shaft to another, or to a rack that translates. Numerous applications exist in which a constant angular velocity ratio (or constant torque ratio) must be transmitted between shafts. Based on the variety of gear types available, there is no restriction that the input and the output shafts need be either in-line or parallel. Nonlinear angular velocity ratios are also available by using noncircular gears. 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 《机械工程专业英语》测验题(23-26)
七、将下列词组译成汉语
80. the design specifications中国设计规范
81. the industrial engineering工业工程
82. the machining industry加工行业 83. the machine shops机器商店
84. machine tool机床85. angular displacements角位移
86. The electric motor电机87. transmission Linkage传输连接
88. the cutting force切削力 89. the static loads静态负荷
90. the dynamic loads动态载荷 91. the grinding wheel砂轮
92. lubricating oil润滑油93. the
cutting fluids切削液
94. protective guards防护装置 95. the cutting tool刀具
96. the range of feeds进给量 97. engine lathes普通车床
98. turret lathes六角车床99. the boring machine镗床
100. the drilling machines钻床 101. the milling machines铣床
102. the broaching machines绞孔机；拉床103. the sawing machines锯床
104. the cylindrical grinder外圆磨床105. the centreless grinders无心磨床106. the surface grinders平面磨床 107. the chemical milling铣削
108. the ultrasonic machining超声波加工109. a tool holder刀架
110. a compound rest复式刀架 111. the feed screw丝杆。