英语考题00.docVIP

陕西航空职业技术学院 2010~2011学年第二学期《机电专业英语》结课作业 班级： 学号： 姓名： 成绩： 1.将给定的英文材料抄写在下边，然后翻译成汉语。 English: Passage4: Characteristics and Selection of Machining Centers The major Characteristics of machining centers are summarized here: 1 Machining centers are capable of handling a wide variety of part sizes and shapes efficiently , economically, repetitively ,and with high dimensional accuracy with tolerances in the order of +0.0025mm. 2 These machining are versatile and capable of quick changeover from one type of product to another. 3 The time required for loading and unloading workpieces, changing tools , gauging of the part , and troubleshooting is reduced. Therefore productivity is improved,thus reducing labor requirements (particularly skilled labor) and minimizing production costs. 4 These machines are equipped with tool-condition monitoring devices for the detection of tool breakage and wear as well as probes for tool-wear compensation and for tool positioning . In-process and post-process gauging and inspection of machined workpieces are now features of machining centers. 5 These machines are relatively compact and highly automated and have advanced control systems, so one operator can attend to two or more machining centers at the same time , thus reducing labor costs. Because of the high productivity of machining centers ,large amounts of chips are produced and must be collected and disposed of properly;this is referred to as chip management.Several designs are available for chip collection with one or more spiral (screw) or chain conveyors that collect the chips along troughs in the machine and deliver them to a collecting point. Machining centers are available in a wide variety of sizes and features, and their costs range from about $50000 to $1 million and higher . Typical capacities range up to 75KW. Maximum spindle speeds are usually in the range of 4000 to 8000rpm,and some are