【正文】 experience downtime. This problem led to the development of puter numerical control. The development of the microprocessor allowed for the development of programmable logic controllers (PLCs) and microputers. These two technologies allowed for the development of puter of puter numerical control (CNC). Whit CNC, each machine tool has a PLC or a microputer that serves the same purpose. This allows programs to be input and stord at each individual machine tool. It also allows programs to be devsloped offline and downloaded at the individual machine tool. CNC solved the probiems associated with downtime of the host puter, but it introduced another problem known as data management. The same program might be loaded on ten different microputers with no munication among them. This problem is in the process of being solved by local area works that connect microputers for better data management. 三 、 Programmers Skillful partprogrammers are a vital requirement for effective utilization of NC machine tools. Upon their efficiency of those machines and the financial payback of the significant investment in the machines themselves, the piant’s NCsupport facilities, and the overhead costs involved. Skillful NC partprogrammers are scarce. This reflects not only the general shortage of experienced people in the meyalworking industries but also the increasing demand for programmers as industry turns more to the use of numerically controlled machines to increase the capability, versaility, and productivity of manufacturing. On an industrywide basis,the obvious answer is to create new programmers by training themand there are a number of sources for such training. But first,what qualifications should programmers have, and what must programming trainees learn? According to the National Machine Tool Builder’s Assn booklet ―Selecting an Appropriate NC programming Method,‖the principal qualifications for manual programmers are as follows: Manufacuring Experience Programmers must have a thorough understading of the capabilities of the NC machines being programmed, as well as an understanding of the basic capabilities of the other machines in the shop. They must have an extensive knowledge of, and sensitivity to, metalcutting principles and practices and practices, cutting capabilities of the tools, and workholding fixtures and techniques. Programmers properly trained in these manufacturingengineering techniques can significantly reduce production costs. Spatial Visualization Programmers must be able to visualize parts in there dimensions, the cutting motions of the machine, and potential interferences between the cutting tool, workpiece, fixture, or the machine itself. 機(jī)械專業(yè)中英文文獻(xiàn)翻譯 Mathematics A working knowledge of arithmetic, algebraic, trigonometric, and geometric operations is extremely important. A knowledge of higher mathematics, such as advanced algebra, calculus,etc, is not normally required. Attention to Details It is essential that programmers be acutely observant and meticulously accurate individuals. Programmers errors discovered during machine setup can be very expensive and timeconsuming to correct. “ Manual programmer,” the booklet nots elsewhere, ―requires the programmer to have moredetailed knowledge of the machine and contril, maching practices, and methods of pution than dose puteraided programming. Computeraided programming, on the other hand, requires a knowledge of the puter programming language and the puter system in order to process that language. In general, manual programmer is more tedious and demanding because of the detail involved. In a puter –aided programming system, this detail knowledge is embodied in the puter system(processor, postprocessor, etc).‖ Experts in the NC and training fields typically agree on these qualifications and requirementsadding such subsidiary details as a knowledge of blueprint reading, machinability of different metals, use of shop measuring instruments, tolerancing methods, and practices. Where should you look for candidates? First of all, in your own plantout on the shop floor. Edward F. Schloss, a Cincinnati Milacron sales vice president, puts it this way: ―We’ve had excellent success with good lathe operators and good boringmill hands. They don’t know it, but they’ve been programming most of their working lives, and they know basic shop math and trigonometry. You can teach them programming rather handily. Conversely, though, it’s