机械设计制造及其自动化专业英语

机械设计制造及其自动化专业英语

Chapter One Materials and Mechanical Elements Lesson 1Introduction for Materials Designers and engineers are usually more interested in the behavior of materials under load or when in amagnetic field in why they behave as they do.Yet the better one understands the nature of materials and the reasons for their physical and mechanical properties the more quickly and wisely will he/she be able to choose the proper material for agiven design.Generally,a material property is the measured magnitude of its response to astandard test performed according to astandard

procedure in agiven environment.In engineering materials the loads are mechanical or physical in nature and the properties are recorded in handbooks or,for new materials,are made available by the

supplier.Frequently such information is tabulated for room-temperature conditions only,so when the actual service conditions are at subfreezing or elevated temperatures,more information is needed. 第一章材料和机械零件 第一课材料介绍

设计者和工程师们通常都会对在加载状态下或处于磁场中的材料的性能更感兴趣，而不关心它们为什么具有这个性能。然而，一个人若能更好地理解这些材料的性质和它们的物理和机械的性能原因，了解得越清楚，他/她就能更快速和准确地选择合适的材料。通常，材料性能是在给定的环境条件下按照规定的方法进行的标准试验所获得的测定值。事实上，工程材料中的加载实质上是机械的或物理的加载，并且性能是记录在手册上的，或者，对于新材料来说，是应由供应商来提供性能手册的。一般来说类似的信息仅仅是在室温条件下被列表显示的，因此，当实际的操作条件是在冰点以下或在高温条件下，则会需要更多的信息。

Lesson 4Gears Helical gears have certain advantages；for example,when connecting parallel shafts they have ahigher loadcarrying capacity than spur gears with the same tooth numbers and cut with the same

cutter.Because of the overlapping action of the teeth,they are smoother in action and can operate at higher pitch-line velocities than spur gears.The pitch-line velocity is the velocity of the pitch circle.Since the teeth are inclined to the axis of rotation,helical gears create an axial thrust.If used singly,this thrust must be absorbed in the shaft bearings.The thrust problem can be overcome by cutting two sets of opposed helical teeth on the same blank.Depending on the method of

manufacture,the gear may be of the continuous-tooth herringbone variety or adouble-helical gear with aspace between the two halves to permit the cutting tool to run out.Double-helical gears are well suited for the efficient transmission of power at high speeds. 第四课齿轮

斜齿轮有某些优点；例如，在具有相同齿数且用同样的刀具来加工的情况下，连接平行轴的斜齿轮的承载能力要比直齿轮更高一些。由于轮齿的重叠作用，斜齿轮在运动中比直齿轮更平稳，并且能够以更高的节线速度来运行。节线速度就是节圆的线速度。由于轮齿向轴线的旋转方向倾斜，故斜齿轮产生了一个轴向推力。如果是单个的齿轮，这个推力必定会被轴向轴承吸收。通过在同一个坯件上切削两组相对的斜齿轮，能够克服推力的问题。根据不同的制造方法，齿轮可以是连续的人字形齿轮，或者是在两列斜齿之间留一间隙的双斜齿形齿轮，以便切削刀具通过。双斜齿形齿轮更适合以高速度进行高效地传送。

Lesson 6Dimensioning The design of amachine includes many factors other than those of determining the loads and stresses and selecting the proper materials.Before construction or manufacture can begin,it is necessary to have complete assembly and detail drawings to convey all necessary information to the shop men.The designer frequently is called upon to check the drawings before they are sent to the shop.Much experience and familiarity with manufacturing processes are needed

before one can become conversant with all phases of production drawings. Drawings should be carefully checked to see that the dimensioning is done in amanner that will be most convenient and understandable to the production departments.It is obvious that adrawing should be made in

such away that it has one and only one interpretation.In particular,shop personnel should not be required to make trigonometric or other involved calculations before the production machines can be set up. 第六课标注

要设计一个机床除了要考虑那些已确定的负载和应力并且选择合适的材料以外，还包括很多其他的因素。在构造和加工开始以前，必须要把完整的装配图和详细的零件图的全部有用的信息传达给工人。设计者经常要在图纸未被送到车间以前检查核对图纸。每个人在熟悉生产图纸的各个阶段之前都必须具有丰富的经验并精通加工工艺。

应该仔细检查图纸，为生产部门作标注时须用一种最合适和最易理解的方式进行，很明显，一张图纸应该是有且只有一种解释的。尤其是不能要求车间工人先进行三角或其他复杂的计算后才能去调整机床。

Chapter Two Machine Tool,Cutting Tool,Jig and Fixture Lesson 1Engine Lathe(Center Lathe)

An engine lathe is shown diagrammatically in Fig.2.1a：it consists of ahorizontal bed supporting the headstock,the tailstock,and the

carriage.All machine tools must have ameans of supporting or holding the workpiece.In Fig.2.1 the workpiece is gripped at one end by achuck

mounted on the end of the main spindle of the machine and is supported at the other end by acenter mounted in the tailstock.The tailstock can be clamped at various positions along the bed to accommodate workpieces of various lengths.Short workpieces need only be gripped by the chuck. Primary motion,the rotation of the workpiece(motion C'),is provided by the movement of aseries of gears driving the main spindle,the gears

being driven by an electric motor mounted at the rear of the machine.The main spindle and the gears are all mounted in the headstock.Levers on the front of the headstock allow various rotational speeds to be sele cted.

第二章机床，切削刀具，钻模和夹具 第一课车床(普通车床)

一个普通车床的结构如图2.1a所示：它由支撑着主轴箱的卧式床身、尾座以及拖板三部分组成。所有的机床必须都要有一种支撑或夹紧工件的方式。在图2.1中，工件通过安装在机床主轴末端的卡盘在一端被夹紧，并且由装配在尾架上的顶尖在另一端被支撑。根据被加工工件长度的不同，尾架沿着床身被装夹在不同的位置。短的工件仅需要由卡盘夹紧。

主运动，即工件的旋转运动(也就是C'点的运动)，是由轮系驱动主轴实现工件旋转的，齿轮通过装夹在车床尾部的电机来带动它旋转。主轴和齿轮都装夹在主轴箱中。主轴箱前部的手柄能够根据实际需要选择不同的旋转速度。 Lesson 2Horizontal Milling Machine(Horizontal Miller)

There are two main types of milling machines：horizontal and vertical.These words again refer to the orientation of the main

spindle.In the horizontal-milling machine shown in Fig.2.5 the milling

cutter is mounted on ahorizontal arbor driven by the main spindle.The tools are therefore rotated(motion C)and the work fed continuously(motions X'or Y').

The simplest operation,slab milling,is used to generate ahorizontal surface on the workpiece,as shown in Fig.2.5.The figure shows the

conventional slab-milling operation；if the workpiece had been fed in the opposite direction,it would tend to climb onto the work surface,and this type of slab milling is called\that the forces and power consumption are less in climb milling than in conventional milling.However,high rigidity of the machine tool and work and tool-holding devices is required for this operation. 第二课卧式铣床

铣床有两种主要类型：卧式和立式。这两种铣床再一次提到了主轴的方向。如图2.5所示的卧式铣床，铣刀被装在水平方向的刀杆上，这个刀杆由主轴来驱动。刀具因此是旋转的(C运动)，并且工件是连续地进给(X'、Y'方向的运动)。 平面铣的加工方式最简单，用来加工工件的水平表面，如图2.5所示。该图给出了平面逆铣加工；如果工件以相反的方向进给，刀具就像在工件表面上爬行一样，这种类型的平面铣也叫\顺\铣。一些证据表明，顺铣中的力和功率的消耗比逆铣中的少。然而，这就要求机床、工件和夹具要具有更高的硬度。 Lesson 3Shaping Machine(shaper)

The shaper is asmall machine on which the primary motion is

linear(Fig.2.17).The single-point tool is gripped in atoolhead mounted on the end of aram.The ram is made to move backward and forward(X motion)either by amechanical drive system or ahydraulic piston and cylinder.The cutting stroke is the forward stroke,and with either

mechanical or hydraulic shapers the forward ram speed is slower than the speed on the return stroke,causing the production time to be reduced as much as possible.A quick-return mechanism often used in mechanical

shapers is shown in Fig.2.18.In all shapers the length of the stroke can be adjusted to suit the particular workpiece being machined.The feed is applied to the workpiece in increments at the end of the return stroke of the ram by arachet-and-pawl mechanism driving the lead screw in the crossrail.

Shapers are most commonly used to machine flat surfaces on small components and are only suitable for low-baton quantities.For the

machining of ahorizontal surface(Fig.2.17),the workpiece is fed horizontally(Y'motion)；for vertical surfaces,the workpiece is fed vertically(Z'motion). 第三课牛头刨床(成型机)

牛头刨床是一个小型机床，它的主运动是直线运动(图2.17)。它的单刃刨刀被夹紧在刀架上，装卡在滑枕的末端。机械的驱动或者液压的活塞缸使得滑枕在X轴方向上进行前后移动。它向前供进的行程即为切削行程，并伴随着机械或者液压的成型机，滑枕向前的速度要比它回程的速度慢得多，这就会使加工时间尽可能的快，以提高工作效率。通常，用在机械牛头刨床的快回机械如图2.18所示。在所有的牛头刨床中，回程的长度均可根据需要做出相应的调整以适应不同的待加工工件。在滑枕返程的末端，进给被应用于工件的增量上，通过横导轨内的丝杆来驱动棘轮棘爪机构。

牛头刨床大多用于加工普通的小零件的平面表面，并且仅适合小批量加工生产。对于一个机件的水平表面的加工(图2.17)，工件沿水平方向进行进给(沿Y'轴方向运动)；对于垂直表面的加工，工件以垂直的方向进给(Z'轴方向)。

Lesson 4Automatic Machines Afinal class of automatic lathe is the multispindle automatic.These lathes are basically flexible,rotary-transfer machines where each spindle holding acollet or chuck is indexed around the various tooling positions so that during each indexing cycle acompleted component is produced.Drum cams instead of disk cams are used in these machines.

Another class of machine tool that can be mechanized is the internal or external cylindrical grinder.When fitted with mechanisms for loading

workpieces automatically and with automatic wheel-dressing devices,these machines can continually produce finished components.The workpieces are often stacked in amagazine,and the operator simply ensures that the magazine is replenished with workpieces at suitable intervals.Because the components are small and the machining forces light,magnetic chucks are often employed to facilitate automatic work holding. 第四课自动机床

最后一组的自动车床是多主轴自动机床。这类机床基本上是灵活的旋转自动机，它的每一根轴上都有一个夹头或卡盘，可以绕不同位置的刀具转位，因此，每转位一次就加工出一个零件。在这类机床中，凸轮轴取代了盘形凸轮被使用。