机电技术专业英语-Lesson-9-机械零件含译文

Lesson NineMachine ElementsHowever simple, any machine is a combination of individual components generally referred to as machine elements or parts. Thus, if a machine is completely dismantled, a collection of simple parts remains such as nuts, bolts, springs, gears, cams and shaftsthe building block of all machinery. A machine element is, therefore, a single unit designed to perform a specific function and capable of combining with other elements. Sometimes certain elements are associated in pairs, such as nuts and bolts or keys and shafts. In other instances, a group of elements is combined to form a subassembly, such as bearings, couplings and clutches.The most common example of machine elements is a gear, which, fundamentally, is a combination of the wheel and the lever to form a toothed wheel. The rotation of this gear on a hub or shaft drives other gears that may rotate faster or slower, depending upon the number of teeth on the basic wheels.Other fundamental machine elements have evolved from wheel and lever. A wheel must have a shaft on which it may rotate. The wheel is fastened to the shafts with couplings. The shaft must rest in bearings, may be turned by a pulley with a belt or a chain connecting it to a pulley on a second shaft. The supporting structure may be assembled with bolts or rivets or by welding. Proper application of these machine elements depends upon knowledge of the force on the structure and the strength of the materials employed.The individual reliability of machine elements becomes the basis for estimating the overall life expectancy of a complete machine.Many machine elements are thoroughly standardized. Testing and practical experience have established the most suitable dimensions for common structural and mechanical parts. Through standardization, uniformity of practice and resulting economies are obtained. Not all machine parts in use are standardized, however. In the automotive industry only fasteners, bearings, bushings, chains, and belts are standardized. Crankshafts and connecting rods are not standardized.Vocabularycombinationn. 组合individualadj. 单独的，各个的，个别的，特殊的componentn. 元件，构件，部件dismantlen. 分解（机器），拆开，拆卸nutn. 螺母springn. 弹簧，板簧，簧片；弹力，弹性；v. 弹回，弹跳gearn. 仪器，装置；（机动车辆的）传动装置，排档齿轮boltn. 螺栓；（门、窗等的）插销camn. 凸轮，偏心轮；样板，靠模，仿形板levern. 杠杆，控制杆，操作杆shaftn. 柱身；连杆；传动轴的旋转轴machineryn. 机器associatevt. 联合，结合，参加，连带keyn. 键，电键，开关；楔，销；钥匙subassemblyn. 段；组件；局部装配couplingn. 联轴节，联轴器；联结器，联合器clutchn. 离合器，联轴器；夹紧装置fundamentallyadv. 基本上hubn. 轮rotatevi. （使某物）旋转或转动evolvevt. 进化，演变；开展，发展，展开assemblevt. 安装，装配，组合；集合，集中；n. 组件pulleyn. 滑轮（组）；滑车；皮带轮rivetn. 铆钉；v. 铆接，铆weldv. & n. 焊接，熔焊reliabilityn. 可靠性，安全性，准确性estimatevt. 估计，估算，计算，测定，评价expectancyn. 期望，预期thoroughlyadv. 完全地，充分地，彻底地standardizevt. 标准化，统一标准；标定，校准establishvt. 确定，制定；建立，创办，产生；使固定dimensionn. 尺寸，尺度；范围，方面bushingn. (=bush) 衬套；轴衬；轴瓦；电(绝缘)套管uniformityn. 均匀性，一致性automotiveadj. 自动的，自动车的crankn. 曲柄refer to指的是，称为，涉及，关于combine with与结合机械零件无论何种简单的机床，都是由单一的元件即机械零件或部件组成的。因此，假如把机床完全拆卸，就可得到像螺母、螺栓、弹簧、齿轮、凸轮和轴等简单零件，这些零件是所有机器的组合元件。所以，机械零件就是用来设计可以执行某种具体功能，而且能与其他零件配合的简单零件。 有时候某些特定的元件必须成对地工作，例如螺栓与螺母，键与轴。在其他情况下，一组零件组成一装配体，比如轴承、联轴器与离合器。机械零件中最常见的是齿轮，它实际上是由轮子和杆组合成的有齿的轮子。在轴套或轴上旋转的齿轮驱动其他齿轮作加速还是减速运动取决于主动齿轮的齿数。其他基本机械零件包括轮子和杆。轮子必须装在轴上才可以转动。轮子用联轴器夹紧固定在轴上，轴必须安装在轴承里，由带或链条与第二根轴相连，并带动第二根轴转动。支承结构可用螺栓、铆钉或通过焊接固定装配在一起。这些机械零件能否正确使用，取决于是否懂得作用于结构上的力和所用材料的