机器零件--机械类英语考试

Mechanical Components

机械零件

1. Shaft

Solid Shaft AS a machine computer, a shaft is commonly a cylindrical bar that supports and rotates with devices for receiving and delivering rotary motion and torque.

Flexible Shaft Compared with solid shafts, flexible shafts can be bent too much smaller radii without being overstressed.

1. 轴

实心轴：作为一个机械零件，它通常是一根圆柱形的棒，它支撑各种装置并随其旋转，借以接受和传递旋转运动及转矩。

柔性轴：与实心轴相比，它可以弯曲至更小的半径而不会产生过应力。

2. Shaft Accessories

Keys, Splines, and Pins The primary purpose of keys, splines, and pins is to prevent relative rotary movement.

A commonly used type of key has a square cross section and is sunken half in the shaft and half in the hub of the other member. Another common type of key has a rectangular cross section with a depth to width ratio 0.75.Both of these keys may either be straight or tapered in depth.

Splines are permanent keys integral with the shaft, fitting in key ways cut in the hub. The dimensions of spline fittings are standardizes for both permanent (press) fits and sliding fits.

Tapered circular pins can be used to restrain shaft-mounted members from both axial and rotational movement.

2.轴的附件

键、花键和销：键、花键和销的主要用途是阻止零件之间相对转动。 一种常用类型的键有正方形截面，且一半陷入轴里而一半则在另一半的轮毂里。另一类常见的键有深宽比为0.75的矩形截面。这两种类型键可以是直的，也可以在高度上有锥度。

花键是与轴做成一体的永久键，与轮毂里切出的键槽相配合。静配合和动配合的花键配合尺寸都已标准化。

有锥度的圆销可用于限制安装在轴上的元件作轴向运动和旋转运动。

3. Clutches

A clutch is a device for quickly and easily connecting or disconnecting a rotary shaft with a rotating coaxial shaft. Clutches are usually placed between the input to a machine and the output shaft from the driving motor, and provide a convenient means for starting and stopping the machine and permitting the driver or engine to be started in an unload state.

A mechanical clutch may provide either a positive drive with no slip or the torque transmitted may depend on friction.

3.离合器

离合器是一种可快速方便地接合或分离一个转轴和另一个旋转着的同心轴的组件。离合器通常安装在机器的输入轴和驱动马达的输出轴之间，它提供了启动和停止机器的一种方便而快捷的方法，同时允许驱动马达或发动机在空载状态下启动。

机械离合器既可提供无滑动的强制传动又可依靠摩擦而传输转矩。

4. Screws

Screws have been used as fastener for a long time, a screw consists of a circular cylinder (or truncated cone) with a helical groove in it. Screws with screwdriver slots have heads of several shapes, such as flat, oval and round.

Screws with hexagonal heads are usually known as cap screws. These screws are used to clamp machine parts together when one of the parts has an internal thread. If neither parts is threaded a bolt must be used, which consists of a screw with a hexagonal head, a nut (hexagonal ring with an internal thread), and usually a washer (flat ring).

4.螺钉

螺钉长期以来作紧固件作用。螺钉由带有螺旋状凹槽的圆柱体或斜截头圆锥构成。

带有螺钉起子槽的螺钉有几种形状的顶端，如平的、椭圆形的、圆形的。 带有六角形顶端的螺钉通常称为有头螺钉。这类螺钉用于当零件之一有内螺纹时把机器的零件加紧在一起。如果零件上未切出螺纹，则必须使用螺栓。螺栓由带有六角形顶端的螺钉、螺母（是一个有内螺纹的六角环）、通常还有一个垫圈组成。

5. Springs

A spring is a load-sensitive, energy-storing device, the chief characteristics of which are an ability to tolerate large deflections without failure and to recover its initial size and shape when loads are removed.

Springs are used for a variety of purposes, such as supplying the motive power in clocks and watches, cushioning transport vehicles, measuring weights, making resilient connections, and providing shock protection for delicate instruments during shipment.

5.弹簧

弹簧是一个对载荷敏感、可储存能量的元件，其主要特性是允许大的变形而不失效，且卸载之后能恢复到初始尺寸和形状。 弹簧可用于多种途径，如在钟和手表里提供动力，对运输车辆减震，称重，作弹性连接以及在装运过程中对精密机械提供抗震保护。

6. Ball Bearings

Ball bearings are used in almost every kind of machine and device with rotating parts. The bearing must be provided with adequate mounting, lubrication, and sealing.

A ball bearing usually consists of four parts: an inner ring, an outer ring, the ball and the cage or the separator. To increase the contact area and permit larger loads to be carried, the ball runs in curvilinear grooves in the rings. The radius of the groove is slightly larger than the radius of the ball and a very slight amount of radial play must be provided. The bearing is thus permitted to adjust itself to small amount of angular misalignment in the assembled shaft and mounting. The separator keeps the balls evenly spaced and prevents them from touching each other.

Ball bearing is made in a wide variety of types and sizes. The radial bearing is able to carry a considerable amount of axial thrust. However, when the load is directed entirely along the axis, the thrust type of bearing should be used. The angular contact bearing will take care of both radial and axial loads. The self-aligning ball bearing will take care of large amount of angular misalignment.

6.球轴承

球轴承几乎用于每一种带有旋转零件的机器装置中。它必须适当地安装、润滑和密封。

一个球轴承通常由四部分组成：内圈、外圈、钢球和保持架。为了增加接触面积且允许承受更大的载荷，钢球在环的曲线形凹槽内运动，凹槽的半径稍大于钢球的半径且有微量径隙，因此允许球轴承在装配好的轴与支座之间将其自身调整至少量角度误差。保持架使钢球均匀地分布且防止钢球间彼此接触。

球轴承可被制成各种各样的类型和尺寸。径向轴承能承受相当大的轴向推力；但当载荷完全沿着轴向时，则应采用止推轴承。角接触球轴承既能承受径向载荷，又能承受轴向载荷。自调节球轴承可容许较大的角误差 。

7. Cams

A cam is a machine member that drives a follower through a specified motion. By the proper design of a cam, any desired motion to a machine member can be obtained. As such, cams are widely used in almost all machinery. They include internal combustion engines, a variety of machine tools, compressors and computers. In general, a cam can be designed in two ways.

(1) The profile of a cam is so designed to give a desired motion to the follower. (2) To choose a suitable profile to ensure a satisfactory performance by the

follower.

A rotary cam is a part on a machine, which changes cylindrical motion to straight-line motion.

The purpose of a cam is to transmit various kinds of motion to other parts of machine.

Practically every cam must be designed and manufactured to fit special requirements. Though each cam appears to be quite different from the other, all of them work in similar way. In each case as the cam is rotated or turned, another part is connected with the cam, called a follower, is moved either right or left, up and down, or in and out. The follower is usually connected to other parts on the machine to accomplish the desired action. If the follower loses contact with the cam, it will fail to work.

Cams are classified according to their basic shapes. (1) Plate Cam

(2) Translation Cam (3) Cylindrical Cam (4) Face Cam

7.凸轮

凸轮是一个驱动从动件实现某一具体的机械运动。通过恰当的凸轮结构设计，可使机器零件获得任何想要的运动。这样便使凸轮广泛地用于几乎所有的机械设备中，包括内燃机、各种机床、压缩机和计算机。一般一个凸轮可按两种方式设计。

（1）把凸轮的轮廓设计成所要的运动传给从动件。 （2）选择合适轮廓，保证从动件满足运动要求。

凸轮的用途是把各种各样运动传输到机器的其它零件。 实际上每一个凸轮必须适应于特殊需要来设计和制造。虽然每一个凸轮看起来与其它的凸轮有很大的不同，但是所有的凸轮以相似的方式工作。在每一种情况下，当凸轮旋转或转动时，与凸轮接触的另一个零件叫做从动件。如果从动件与凸轮不接触，就不能工作。 凸轮是按照它们的基本形状来分类的。 1 板（盘形）凸轮 2 楔形凸轮 3 圆柱形凸轮 4端面凸轮

8. Gears

The transmission of rotary motion from one shaft to anther occurs in nearly every machine one can imagine. Gears constitute one of the various means available for transmitting this motion.

A gear is virtually a wheel with very accurately shaped teeth. These teeth mesh with teeth of another gear, thus providing as positive-motion drive. The speed ratio between shafts carrying a pair of gears depends upon the numbers of teeth in the gears. For example, a 20-teeth gear drives a gear of 50 teeth, the smaller gear will have to turn 2.5 times to cause the larger one to make 1 turn.

Various types of gearing have been developed for different purposes. If the shafts are parallel, any of three types may be used, spur, bevel, or herringbone. Spur gears are the simplest and least expensive type. They are generally used on drives requiring moderate speed. Bevel gears serve to transmit power between two intersecting shafts. Rack-and-pinion drives are used where it is desirable to transmit the rotary motion of one part into linear motion for the other part or vice versa.

Spur gears are used to transmit rotary motion between parallel shafts; they are usually cylindrical, and the teeth are straight and parallel to the axis of rotation.

8.齿轮

从一个轴向另一个轴传递旋转运动在几乎所能想象的每一种机器中都存在，齿轮便是能够用来传递这种运动的各种方式方法中最好的方法之一。

齿轮实质上是带有精确成型齿的轮子，这些齿与另一个齿轮的齿啮合，因而就提供了强制的驱动。装有一对齿轮的轴之间的转速比取决于齿轮的齿数。例如，如果一个20齿的齿轮驱动一个50齿的齿轮，较小的齿轮转2.5圈，可使较大的齿轮旋转1圈。 为了不同的用途，人们已研制出不同类型的齿轮。如果两个轴平行，可采用直齿圆柱齿轮、斜齿轮或人字齿轮三类齿轮中任意一

种。直齿圆柱齿轮是最简单和最经济的，它一般用在需要中速驱动的装置。锥齿轮用在两个交叉轴之间传递动力。如希望把一个零件的旋转运动转换为其它零件的线性运动时可采用齿条与小齿轮驱动，反之亦然。

直齿圆柱齿轮用于平行轴之间传递旋转运动；它们通常是圆柱形的，且齿是直的并且平行于旋转轴。

9. Worm Gear Pairs

Worm gear pairs transmit motion between two shafts. The shafts are usually at right angles to each other but do not lie in the same plane. The teeth on the worm slide against the teeth of the worm wheel, producing a rolling action. The worm turns the worm wheel.

The worm is the member having the screw-like thread, and worm teeth are frequently spoken of as threads. Worms which are commonly used have 1 to 8 teeth. There is no definite relation between the desired of teeth and the pitch diameter of a worm. Threads of worm may be made with either right-hand or left-hand threads, depending upon the desired direction of rotation of the worm gear pairs.

Worm wheel are similar to bevel gears and are generally used to connect skew shafts (generally at right angles) transmitting high velocity ratios. The worm wheel give line contact between mating teeth unlike a point contact in the case of bevel gears. This improves the load carrying capacity of the gear train.

The load carrying capacity can further be improved by using an enveloping worm.

9.涡轮

涡轮副在两个轴之间传递运动。轴通常彼此成直角，但不在一个平面内。蜗杆的齿在涡轮的齿上滑动，产生滚动运动。蜗杆驱动涡轮转动。

蜗杆是有螺旋状螺纹的部件，蜗杆的齿数经常被叫做头数。常用的蜗杆有1至8个齿，齿与蜗杆节圆直径之间没有确切的关系。蜗杆上的螺纹可制成右旋又可制成左旋，这取决与涡轮预定的旋转方向。

涡轮类似于锥齿轮，通常用于连接斜交轴（通常是90°），传递高的速度比。涡轮在两啮合齿间是线接触，不像某些情况下的斜齿是点接触。这提高了齿轮承载能力。

承载能力可以通过包络线蜗杆进一步提高。

10. Couplings

A coupling is a device for connecting the ends of adjacent shafts. In machine construction, couplings are used to effect a semi-permanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machine, but it can be broken and restored in an emergency or when worm parts are replaced.

There are several types shaft couplings; their characteristics depend on the purpose for which they are used. If an exceptionally long shaft is required for a line shaft in the manufacturing plant or a propeller shaft on ship, it is made in sections that are coupled together with rigid couplings.

In connecting shafts belonging to separate devices (such as an electrical motor and gearbox), precise aligning of the shafts is difficult and a flexible coupling is used.

This coupling connects the shafts in such a way as to minimize the harmful effects of shaft misalignment. Flexible couplings also permit the shafts to defect under their separate systems of loads and to move freely (float) in the axial direction without interfering with one another. Flexible couplings can also serve to reduce the intensity of shock load and vibrations transmitted from one shaft to another.

10.连轴器

连轴器是连接相邻轴末端的装置。在机构结构里，连轴器用来在相邻的旋转轴之间起到半永久连接作用，联轴器在机器的有效寿命里不被破换，在此意义上连接是永久的，但是在紧急情况或替换损坏部件时，可以断开和复原。

有几种类型的联轴器，它们的特点取决于其使用目的。如果一个特别长的轴需要在制造厂中做动力轴或在船上做螺旋桨，则它们被分段制造，各部分用刚性联轴器连接。

在联接属于分离机构的轴时（如电动机与齿轮箱），轴的精确调整困难，可使用柔性联轴器。这种联轴器以把轴偏差的有害作用降低至最小的方式连接轴。同样联轴器也允许轴在它们各自系统的载荷作用下偏移，并且在轴向自由移动（漂移），而不影响另一个轴。柔性轴联轴器也可用来降低冲击载荷的强度和从一个轴传递到另一个轴的震动。