1、机械专业中英文文献翻译 中文 4935 字 Modern Design and Manufacturing 一、 The Computer and Manufacturing The computer is bringing manufacturing into the Information Age. This new tool, long a familiar one in business and management operations, is moving into the factory, and its advent is changing manufacturing as c
2、ertainly as the steam engine changed it 100 years ago. The basic metalworking processes are not likely to change fundamentally, but their organization and control definitely will In one respect, manufacturing could be said to be coming full circle. The fist manufacturing was a cottage industry: the
3、designer was also the manufacturer, conceiving and fabricating products one at a time. Eventually, the concept of the interchangeability of parts was developed, production was separated into specialized functions, and identical parts were produced thousands at a time . Today, although the designer a
4、nd manufacturer may not become one again, the functions are being drawn close in the movement toward an integrated manufacturing system. It is perhaps ironic that, at a time when the market demands a high degree of product diversification, the necessity for increasing productivity and reducing coats
5、 is driving manufacturing toward inegration into a coherent system, a continuous process in which parts do not spent as much as 95% of production time being moved around or waiting to be worked on . The computer is the key to each of these twin requirements. It is the only tool that can provide the
6、quick reflexes, the flexibility and seed, to meet a diversified market. And it is the only tool that enables the detailed analysis and the accessibility of accurate data necessary for the integration of the manufacturing system. It may well be that, in the future, the computer may be essential to a
7、companys survial. Many of todays businesses will fade away to be replaced by more-productive combinations. Such more-productive combinations are superquality, superproductivity plants. The goal is to design and operate a plant that would produce 100% satisfactory parts wich good productivity. A soph
8、isticated, competitive world is requiring that manufacturing begin to settle for more, to become itself sophisticated. To meet competition, for example, a company will have to meet the somewhat conflicting demands for greater product diversification, higher quality, improved productivity , higher qu
9、ality, improved productivity and prices. The company that seeks to meet these demands will need a sophisticated tool, one that will allow it to respond quickly to customer needs while getting the most out of its manufacturing resources. The computer is that tool. Becoming a superquality, superproduc
10、tivity plant requires the integration of an extremely complex system .This can be accomplished only when all extremely complex system. This can be accomplished only when all elements of manufacturing-design, fabrication and assembly, quality assurance, management, materials handing-are computer inte
11、grated. In product design, for example, interactive computer-aided-design(CAD) systems allow the drawing and analysis tasks to be performed in a fraction of the time allow the drawing and 机械专业中英文文献翻译 analysis tasks to be performed in a fration of the time previously required and greater accuracy. An
12、d programs for prototype testing testing and evaluation further speed the design process. In manufacturing planning, computer-aided process planning permits the selection, from thousands of possible sequences and schedules,of the optimum process. On the shop floor, distributed intlligence in the for
13、m of microprocessors controls, runs automated loading and unloading equipment, and collects data on current shopconditions. But such isolated revolutions are not enough. What is nended is a totally automated system, linked by common software from front door to back. Essentially, computer integration
14、 provides widely and instantaneously available, accurate information, improving communication between departments, permitting tighter control, and generally enhancing the overall quality and efficiency of the entire system. Improved communication can mean, for example, designs that are more producib
15、le. The NC programmer and the tool designer have a chang to influence the product designer, and vice versa. Engineering changes,can be reduced,and those that are required can be handled more efficiently.Not only dose the computer permit them to be specicified more quickly, but it also alers subseque
16、nt users of the data to the fact that a change has been made. The instantaneous updating of production-control data permits better planning and more-effective scheduling . Expensive equipment, therefore, is used more productively, and parts move more efficiently through production, reducing work-in-
17、process coats. Product quality, too, can be improved. Not only are more-accurate designs produced, for example,but the use of design data by the quality-assurance department helps eliminate errors due to misunderstandings. People are enabled to do their jobs better.By eliminating tedious calculation
18、s and paperworknot to mention time wasted searching for informationthe computer not only allows workers to be more productive but also frees them to do what only human being can do: think creatively. Computer integration may also lure new people into manufacturing. People are attracted because they
19、want to work in a modern, technologically sophisticated enviroment. In manufacturing engineering, CAD/CAM decreases tool-design,NC-programming, and planning times while speeding the response rate, which will eventually permit in-hous staff to perform work that is currently being contracted out. 二 、
20、Numerical Control One of the most fundamental concepts in the area of advanced mannufacturing technologies is numerical control(NC). Prior to the advent of NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tolls. Perhaps no
21、ne is more prominent than the limitation of operator skills. With manual control, the quality of the peoduct is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools. Numerical control means the contr
22、ol of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instrutions. Rather than operating a machine tool, an NC technician writes a program that issues operating a machine tool, an NC technician weites a program that issues operational instructions to th
23、e machine tool. 机械专业中英文文献翻译 Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines,they can produce parts more uniformly, they are fastre, and the long-run tooling costs are lower
24、. The development of NC led to the development of several other innovations in manufacturing technology: 1.Electrical discharge machining. 2.Laser cutting. 3.Electron beam welding. Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine t
25、ool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible form an economic perspective using manually cont
26、rolled machine tools and processes. Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U.S.Air Force. The APT(Automatically Programmed Tools)language was des
27、igned at the Servomechanism laboratory of MIT in 1956. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a maj
28、or step forward in the further development of NC technology. The original NC systems were vastly different form those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. A tape reade
29、r was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development. A major problem was the fragility of the punched pa
30、per tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool, the paper tape carrying the programmed instuctions had to be
31、 rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use. This led to th
32、e development of a special magnetic plastic tape. Whereas the paper tape carried the progtammed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper tape, which solved the prob
33、lem of frequent tearing and breakage. However, it still left two other problems. The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instuctions,it was necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape though the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problems of NC asociated with punched paper and plastic tape.
