机械专业英语..ppt

1、机械专业英语,学习要求,1、了解科技英语的表达方式和方法,能够阅读和翻译较简单的本专业相关的科技文章。 2、了解英语科技文章的结构，掌握与本专业有关的英语词汇和专业术语。 3、在学习专业英语的同时，掌握获取外文专业资料及阅读能力。,Part 1 Materials it can provide parts with uniform physical and mechanical properties through out and , depending on the particular material being cast, the design of the part, and the

2、 quantity being produced, its economic advantages can surpass other processes.,Lesson 11 Forging,Vocabulary： press 压力机；压锻 forging 锻造，锻造的 closed impression dies 封闭式型腔模具 stroke 冲程 冲击 ram 锤头；冲头 dies 模具，模子 cavity 腔；中空 block 坯料；毛坯 drop forging 落锤锻 roughly 粗糙地；大体上,Vocabulary： desire 愿望；要求 shape 形状；模形 exac

3、t 精确的；强制要求 the finished piece 成品 drawing the dies together 使两模合拢 forced to take this form 压力成形 brass 黄铜；黄铜制品 hydraulic 液压的；液压传动装置 instead of 代替着；而不是 draft 牵引力 complicate 使复杂化 extrude 挤压，模压 impact 碰撞；冲击,Vocabulary： hammer 落锤，锤头 symmetrical 对称的 irregular 不规则的 sizing operations 精锻工艺 indicate 指示；显示 by a

4、 press goes deeper 深度持续施压 can take 能处理（拿下） rolling 压光，扎制 the final forging 终锻；精锻 overheat 过热 judge 判断 furnace （熔，炼，高）炉 pyrometer 高温计,Forging Processes Metal flow during the forging process normally falls into two categories:upsetting and extrusion. Upsetting occurs when the metal is compressed paral

5、lel to the longitudinal axis of the workpiece. This action enables the metal to flow freely in one direction as in open-die forging, or it can be restrained as in impression-die forging. Extrusion occurs when the metal is compressed parallel to the longitudinal axis of the workpiece and allowed to f

6、low through an orifice(孔) in the die cavity. 锻造工艺中，金属流动通常分为两类：镦粗和挤压。当金属沿平行于工件纵轴线方向被压缩时是镦粗。这一行为使金属能沿一个方向自由流动如开式模锻，或者方向被限制如模膛模锻。当金属沿平行于工件纵轴线被压缩且允许沿模腔的孔流动时是挤压。,自主学习安排,翻译 Lesson 12 下次上课上交 预习 Lesson 15 and Lesson 18,Lesson 15 Introduction of Mechanism,mechanism kinematic kinematic chain link definite con

7、strained unconstrained linkage joint pin revolute prismatic nonlinear,four-bar-linkage prime mover coupler pivot configuration inversion slider-crank mechanism multiloop sketch skeleton diagram envision binary ternary,ternary links quaternary quaternary links cam can followers gear sprocket belt pul

8、ley spherical helical three-dimensional intuitively synthesis kinematician innate,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. 运动链是一个构件系统装置，即若干刚体，它们或

9、者互相铰接或者互相接触，方式上是允许它们彼此间产生相对运动。 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. 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或力为目的的机械装置。,3. The simplest closed-loop linkage is the four-bar lin

10、kage, 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（加一个固定构件）并且有四个销轴。,四杆构件,The link that is connected to the power source or prime mover and has one moving pivot and one ground pivot is called the input link. 连接动力源或第一动件并且具有一个移动铰和一个固定铰的构件叫做输入构件。

11、The slider-crank(or crank and slider) mechanism is a four-bar chain with a slider replacing an infinitely long output link. 曲柄滑块（即曲柄和滑块）机构是一个以一个滑块替换一个无限长的输出件的四杆机构.,The skeleton diagram serves a purpose similar to that of the electrical schematic or circuit diagram in that it displays only the essent

12、ial skeleton of the mechanism, which, however, embodies the key dimensions that affect its motion. 示意图用于电路图解类似的目的，即仅仅表示机构本质的意图，然而，它要体现影响其运动的关键的尺寸。 By degree of freedom we mean the number of independent inputs required to determine the position of all links of the mechanism with respect to ground. 依据

13、自由度，我们可以预定需要的独立输入的数目，以确定所有构件相对于地面的位置，,In kinematic analysis, a particular given mechanism is investigated based on the mechanism geometry plus possibly other known characteristics(such as input angular velocity, angular acceleration, etc) 在运动分析中，根据机构的几何形状加上可能知道的其他特性（如输入角速度，角加速度等）来研究确定一个具体的机构。 8. The

14、 ability to visualize relative motion, to reason why a mechanism is designed the way it is, and the ability to impove on a particular design are marks of a successful kinematician. 想象相对运动的能力，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机构学家的标志。,Four-bar mechanism,When one of the members of a constrained li

15、nkage is fixed, the linkage becomes a mechanism capable of performing a useful mechanical function in a mechine. On pin-connected to the fixed link; the input and output links are usually pivotally connected to the fixed link;the connecting links(couplers) are usually neither inputs nor outputs. Sin

16、ce any of the links can be fixed, if the links are of different lengths, four mechanisms,each with a different input-output relationship, can be obtained with a four-bar linkage. These four mechanisms are said to be inversions of the basic linkage. 当受约束的连杆机构的一个构件被固定时，连杆机构就变成机器里一个可能完成某种有用机械功能的机构。在销接的

17、连杆机构上，输入和输出连杆通常铆接在固定连杆上，连接连杆通常即不是输入连杆也不是输出连杆。由于任一连杆都可以固定，如果连杆长度不同，通过一个四连杆机构可以获得4种机构，每种机构都有不同的输入输出关系。这4种机构可以说是基本连杆的转换。,Lesson 16 Movement Analysis,1、The four-bar linkage may take form of a so-called crank-rocker or a double-rocker or a double-crack(drag-link) linkage, depending on the range of motion

18、 of the two links connected to the ground link. 四杆机构可具有一种被称为曲柄摇杆机构的形式，或者双摇杆机构，或者双曲柄（拉杆）机构，致于称作那一种形式的机构，取决于跟固定构件相连接的两杆的运动范围。,Lesson 18 Cams and gears,cam gear groove mate normal complement collinear lateral stem guide intermittent dwell inertial engage rack conjugate cycloidal involute tolerance spur

19、 gear,offset disk cam tangent concentric camshaft pitch curve herringbone intersect parallel helical gear crossed helical gear worm skew bevel hypoid gear addendum project clearance didendum tooth space backlash,In the case of a disk cam with a radial(in-line) translating roller follower the smalles

20、t 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，可以画出的与凸轮表面相切且与凸轮轴同心的最小圆是基圆。 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 require

21、d follower displacement measured in centimeters or degrees. 一个典型的例子将要求一个含上升停歇返回和可能的另外一个停歇周期，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测量。,3. 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

22、 angular velocity ratio, the shape of their contacting profiles must be such that the common normal passes through a fixed point on the line of the centers. 为了保持恒定角速度，各个齿轮齿廓必须服从齿轮啮合的基本规律：对于一对传递恒定角速度比的齿轮，它们接触齿廓的形状必须是这样：公法线经过两齿轮中心连线的固定点。 The clearance is the amount by which the dedendum (tooth height

23、below the pitch circle) in a given gear exceeds the addendum of its mating gear. 间隙是一个给定齿的齿根高（节圆以下的齿高）大于与其相啮合齿轮的齿顶高的差值。,Gears,Gears are direct-contact bodies,operating in pairs, that transmit motion and force from one rotating shaft to another, or from a shaft to a slide (rack), by means of successi

24、vely engaging projections called teeth. There are four main types of gears: spur, helical,worm,and bevel. 齿轮是直接接触的物体，成对工作。它利用被称为齿的渐进啮合的突出物将运动和力从一个旋转轴传递到另一个，或从旋转轴传递到滑板（齿条）。齿轮有四种类型：直齿轮，斜齿轮，蜗轮蜗杆和锥齿轮。,Lesson 23 Fundamental of machine tools,1.A machine tool provides the means for cutting tools to shape a

25、 workpiece to required dimensions; the machine supports the tool and workpiece in a controlled relationship througth the functioning of its basic members. 机床通过切削工具去使得工件成型以达到所需要的尺寸提供了手段；它通过基础构件的功能作用，以控制相互关系方式支持（夹紧）工具和工件。 2. Angular displacements take place about an axis of rotation; the position of t

26、his axis must be constant within extremely fine limits in machine tools, and is ensured by the provision of precision spindles and bearings. 角位移是围绕一个旋转轴线产生的；该轴线的位置必须在机床中极端精确的限度内保持恒定，而且是靠精密的主轴和轴承来提供保证。,3. The degree of precision achieved in any machining process will usually be influenced by the magn

27、itude of the deflections, which occur as a result of the force acting. 任何加工过程所获得的精度通常将受到由于力的作用所引起的变形量的影响。 The movement generally takes the form of translation in a straight line,but is sometimes angular rotation, e.g. tilting the wheel-head of a universal thread-grinding machine to an angle correspo

28、nding with the helix angle of the workpiece thread. 运动一般采取在直线上运动，但有时是旋转，例如，对应于工件螺纹螺旋角方向而翻转万能螺纹磨床上砂轮头一个角度。,5. To facilitate assembly,maintain accuracy and eliminate “play” between sliding members after wear has taken place, a strip is sometimes inserted in the slides. 为了便于装配、保持精度和发生磨损后减小滑移构件之间的“窜动”，有

29、时在拖板里加入扁条。 Hence in practice slide surfaces are either ground using the edge of a cup wheel,or scraped. （注意：ground是grind 的过去分词） 因此在实践中滑移表面是使用凹面砂轮的刃进行磨削或者刮削。,Lesson 24 Lathes,It is commonly used for the production of flat surface by facing, in which the workpiece is rotated while the cutting tool is

30、moved perpendicularly to the axis of rotation. 车床借助端面切削也普遍用于加工平面，在端面切削加工中，工件旋转，而刀具作垂直于旋转轴方向的移动。 The cross feed is provided with a hand wheel and feed screw for moving the compound rest perpendicular to the lathe way. 以手轮和使小刀架垂直于车床导轨移动的拉杆来提供横向进给。,3. Although a large amount of time is consumed in sett

31、ing up the tools and stops for operation, the turret lathe, once set, can continue to duplicate operations with a minimum of operator skill until the tools become dulled and need replacing. 虽然装刀和加工准备要花费很多时间，但转塔车床一次装刀无需熟练工人就可以连续加工直到刀具变钝需要更换为止。,Lesson 30 Wears of Cutting Tool,1、On the major cutting edge, which is responsible for bulk metal removal, this results in increased cutting forces and higher temperatures which if left unchecked can lead to vibration of the tool and