机械工程专业课件.ppt

1、机械工程专业英语 Specified English for Mechanical Engineering组组 长长：专业英语和普通英语的区别一.词义特点1.根据词类辨明词义 e.g (1)Round(adj)surface reflector is a key unit for the solar engrgy device.曲面反射器是太阳能装置的关键元件。（2）This is the whole round(n)of knowledge.这是全部知识范围。2.区分场合确定词义（不用场合，词义不同，要根据上下文和语言环境来确定词义）e.g:(1)pig:猪 iron 生铁（机械专业）met

2、al 金属锭 copper 生铜 （2）dog：狗（机械专业）鸡心夹头，挡块3.联系上下文活用词义 e.g：（1）There is no physical contact between tool and workpiece.工具和工件之间直接的接触。（2）High-speed gringding does not know this disadvantage.高速磨削不存在这个缺点。4.非谓语动词多 动名词 分词：现在分词和过去分词 不定式e.g：（1）To be a true professional requires lifelong learning.要成为一个名副其实的内行，需要学到

3、老。（2）Heating water does not change its chemical composition.把水加热并不会改变水的化学成分。（3）Matter is anything having weight and occupying space.任何具有重量并占有空间的东西都是物质。5.被动语态多 （1）No work can be done without energy.没有能量决不能做功。（2)All sorts of necessaries of live can be made of plastics.塑 料组成了各种各样的生活必需品。Gear Manufacturi

4、ng MethodsTermionlogy 术语Text tour文本之旅TerminologyAnnularShaped like or forming a ring.环形的，轮状的：形状像环或形成环状。Annular gear 内齿轮,齿圈（也称为internal gear）Hliecal gear 斜齿轮Hob 滚刀Worm 蜗杆Worm gear 1.A gear consisting of a spirally threaded shaft and a wheel with marginal teeth that mesh into it蜗轮蜗杆副2.The toothed whee

5、l of this gear,a worm wheel蜗轮Broach 拉刀Swarf Fine metallic filings or shavings removed by a cutting tool.小铁屑：用锉或剃等加工方法去除的细小金属屑。DressingDressing is the process of conditioning worn grains on the surface of a grinding wheel by producing sharp new edges on grains so that they can cut more efficiently.砂轮

6、修整：使砂轮表面磨钝的磨粒上产生新的锋利的切削刃，使其能够更有效地进行切削工作。Text tourGear planing uses a reciprocating rack,stroking in the direction of the helix on a gear with a gradual generation of form as the rack effectively rolls round the gear blank.The rack is relieved out of contact for the return stroke as in normal shaping

7、 or planing.刨齿采用往复运动的齿条刀，当齿条刀绕齿轮坯料滚切并沿其螺旋线方向运动时，齿形就会被逐渐展成。与普通的刨削加工相同，在回程中齿条刀与齿轮脱离接触。Gear shaping is inherently similar to gear planing but uses a circular cutter instead of a rack and the resulting reduction in the reciprocating inertia allows much higher stroking speeds.插齿加工在本质上与刨齿加工类似，只是采用了圆形刀具来取代

8、齿条刀。Gear shaping（插齿）（插齿）inherently（内在的；固有的）（内在的；固有的）gear planing（刨齿加工）（刨齿加工）circular cutter(圆形刀具）圆形刀具）instead of a rack（齿条刀）（齿条刀）reciprocating inertia（运动惯性）（运动惯性）stroking speeds（行程速度）（行程速度）插齿插齿(gear shaping)：在插齿机上用插齿刀加工在插齿机上用插齿刀加工 齿形的过程。齿形的过程。原理：原理：刀具和工件的运动相当于一对圆柱齿刀具和工件的运动相当于一对圆柱齿 轮传动。轮传动。For helica

9、l gears,a helical guide is required to impose a rotational motion on the stroking motion;such helical guides cannot be produced easily or cheaply so the method is only suitable for long runs with helical gears since special cutters and guides must be manufactured for each different helix angle.加工斜齿轮

10、时，需要有一个能够产生绕插齿运动行程本身旋转的螺旋导轨。这种螺旋导轨不易制造，或者说其制造成本较高。由于对每一种不同螺旋角的齿轮，应该制造不同参数的插齿刀和螺旋导轨，因此这种方法仅适用于斜齿轮的大批量加工。helical gear helical gear 螺旋齿轮；螺旋齿轮；斜齿轮be required to 被要求被要求rotational adj.adj.转动的；回转的；转动的；回转的；helical guide 螺旋导件螺旋导件guide 导轨导轨 n.n.指南；向导；入门书指南；向导；入门书 vtvt.引导；引导；带领；操纵带领；操纵 vi.vi.担任向导担任向导 long runs

11、 大批量加工大批量加工 adj.adj.长期的长期的 n.n.最后最后Gear hobbing,the most used metal cutting method,uses the rack generating principle but avoids slow reciprocation by mounting many“racks”on a rotating cutter.The“racks”are displaced axially to form a gashed worm.Metal removal rates are high since no reciprocation of

12、 hob or workpiece is required.滚齿是最常见的金属切削方法。它采用齿条展成原理，但是通过安装在旋转刀具上的许多“齿条”来避免缓慢的往复运动。这些“齿条”轴向排布，形成了有缝的蜗杆。由于滚刀和工件均不作往复运动，因此滚齿加工时的金属切削率很高。Rack齿条Reciprocation往复A gear shaving cutter looks like a gear which has extra clearance at the root(for swarf and coolant removal)and whose tooth flanks have been gro

13、oved to give cutting edges.It is run in mesh with the rough gear with crossed axes so that there is in theory point contact with a relative velocity along the teeth giving scraping action.剃齿刀形如齿轮，在刀齿的根部有一附加的凹槽(用于排除切屑和冷却液)，在齿面上开许多小槽以形成切削刃。剃齿刀与经过粗加工的齿轮成交错轴啮合传动。这样在理论上沿着轮齿有一个具有相对速度的点接触，从而产生刮削作用。clearanc

14、e 间隙,清杆,清仓swarf 削屑,油污金属切屑,金属切销屑removal 除去,注销注册商标,消除velocity 速度,速率,周转速度Scraping 刮擦,刮削,刮边flanks 拱侧翼,侧面,两侧 Gear grinding is extremely important because it is the main way hardened gears are machined.When high accuracy is required it is not sufficient to pre-correct for heat treatment distortion and gri

15、nding is then necessary.磨齿是非常重要的，因为它是加工淬硬齿轮的主要方法。当对于热处理变形的预先校正达不到齿轮所要的高精度时，就必须采用磨削加工。The fastest gear grinding method uses the same principle as gear hobbing but replaces a gashed and relieved worm by a grinding wheel which is a rack in section.Only single start worms are cut on the wheel but gear rotation speeds are high,100 rpm typically,so it is difficult to design the drive system to give accuracy and rigidity.最快的磨齿齿方法采用与滚齿相同的原理，但是使用截面为齿条的砂轮来取代有排屑槽的蜗杆形滚齿刀。砂轮只能被切削成单头蜗杆形，由于齿轮的转速通常高达100 r/min，因此设计具有所需要的精度和刚度的驱动系统是困难的。