九江学院械工程专业英语期末复习..doc

机械工程专业英语作业及期末复习 作业一 1.Most machining has very low set-up cost compared with forming, molding, and casting processes. However, machining is much more expensive for high volumes. 译文：与成型加工、锻压和铸造工艺相比，大多数机械加工的生产准备成本都较低，然而如果是大批量生产，其成本要高得多。 Turning can occur on both external and internal surfaces to produce an axially-symmetrical contoured part. 译文：车削可以加工外面和内表面以形成具有轴对称的成形工件。 Facing is the producing of a flat surface as the result of a tool’s being fed across the end of the rotating workpiece. 译文：车端面可以加工出一个平面，它是当车刀沿回转工件的端面横向进给的结果。 Threading can be considered as turning since the path to be travelled by the cutting tool is helical. 译文： 车螺纹可以看作是车削，只是车刀所形成的加工轨迹是螺旋线。 many types of lathes are used for production turning . According to purposes and construction ,lathe-type machine tools can be classified as follows: 译文：许多种类的车床都可以用于车削，根据它的目的和结构，车床可以分为以下几种类型。 Engine lathes 普通车床 Vertical lathes 立式车床 Turret lathes 转塔车床 Single-or mulitple-spindle automatic or semi-automatic lathes 单或多轴自动或半自动车床 Contouring lathes 仿形车床 Universal lathes 万能车床 Special-purpose lathes such as crankshaft lathes camshaft lathes ,car wheel lathes and backing-off lathes,etc 专用车床，如曲轴车床、凸轮轴车床、汽车车轮车床、铲齿车床等 作业二 Quality and accuracy are major considerations in making machine parts or structures. Interchangeable parts require a high degree of accuracy to fit together. 译文： 在制造机器零件和结构的过程中，质量和精度是最重要的因素。互换性零件需要有高精度以实现相互配合. Deviations of actual surfaces are divided into four groups to enable assessment, prescription and checking of the permitted inaccuracy during production: 译文:实际加工表面的偏差在进行评估说明和允许误差的检查过程中被分为四类 1. Dimensional deviations; 1尺寸偏差; 2. Shape deviations; 2形状的偏差; 3. Position deviations; 3位置偏差; 4. Surface roughness deviations. 4表面粗糙度的偏差。 Unnecessarily tight tolerances lead to high cost of manufacture resulting from more expensive manufacturing methods and higher reject rates. 译文：不必要的紧公差会导致由于昂贵的制造方法和较高的废品率所带来的高的制造成本。 Transition fit. It is a fit where (depending on the actual sizes