机械类英文论文

1、Manufacturing Technology Facing the 21st Century1Agile Manufacturing Rapid, severe, and uncertain change is the most unsettling market reality that companies and people must cope with today. New products, even whole markets, appear, mutate and disappear within shorter and shorter periods of time. Th

2、e pace of innovation continues to quicken, and the direction of innovation is often unpredictable. Product variety has proliferated to a bewildering degree (Seiko markets 3000 different watches; Philips sells more than 800 color TV models). Agility is a comprehensive response to the challenges posed

3、 by a business environment dominated by change and uncertainty. For a company, to be agile is to be capable of operating profitably in a competitive environment of continually and unpredictably changing customer opportunities. For an individual, to be agile is to be capable of contributing to the bo

4、ttom line of a company that is constantly reorganizing its human and technological resources in response to unpredictably changing customer opportunities. But marketplace change is only one dimension of the competitive pressures that companies and people are experiencing today. At a deeper level, we

5、 are changing from a competitive environment in which mass-market products and services were standardized, long-lived, information-poor and exchanged in one-time transactions to an environment in which companies compete globally with niche market products and services that are individualized, short-

6、lived, information-rich, and exchanged on an ongoing basis with customers. Only those companies that respond to the deeper structural changes taking place in the commercial competition will be able to make sense of and profit from -the superficially chaotic changes occurring at the level of the mark

7、etplace. A more complete definition of agility, then, is that it is a comprehensive response to the business challenges of profiting from rapidly changing and continually fragmenting global markets for high quality, high performance, customer configured goods and services.Agility is, in the end, abo

8、ut making money in and from a turbulent, intensely competitive business environment.2A New Manufacturing Strategy Reforms introduced by companies since the early 1980s to improve their competitiveness just-in-time logistics, the quality movement, "lean" manufacturing-have been tactical res

9、ponses to marketplace pressures. These reforms aim to improve how companies are doing what they are already doing. Although these efforts are appropriate and valuable, they reflect an acceptance of the status quo, rather than a recognition of the need to confront a new competitive reality, one that

10、challenges what companies ought to be doing, not just how they can do a better job of what they are already doing. As a matter of fact, most companies have adopted a succession of tactical initiatives without anchoring the rationale for their implementation in new ends that mandate fundamental chang

11、es, true paradigm shifts in how those companies operate. The result is that, in company after company, managerial reforms has invariably set in. however. Innovative tactics will always be short-lived unless they are embedded in comprehensive organizational change that is in turn anchored in new stra

12、tegic goals.Agility challenges the prevailing modes of organization, management, production, and competitiveness. It is explicitly strategic rather than tactical, taking no established practices for granted. Agile competition demands that the processes that support the creation, production, and dist

13、ribution of goods and services be centered on the customer-perceived value of products. This is very different from building a customer-centered company. Enhancing the satisfaction that a customer experiences in dealing with a company adds value and can improve focus and even efficiency. But custome

14、r-centered operations are fully consistent with the mass -production mode. Centering a company on product lines that enrich customers products whose prices are determined by the value that customers perceive those products to have for themmoves beyond the traditional mass-production system, however

15、efficient it may be.Successful agile companies, therefore, know a great deal about individual customers and interact with them routinely and intensively. Neither knowledge of individual customers nor interaction on this level was relevant to mass-production-era competitors. As suppliers of standardi

16、zed, Uniform goods and services, mass-production-era competitors relied on market surveys that created an abstraction: the "average" or "typical" customer. However, individuality could not be accommodated in a mass -production competitive environment.By contrast, offering individ

17、ualized products not a bewildering list of options and models but a choice of ordering a product configured by the vendor to the particular requirements of individual customers is the feature of agile competition. Success entails formulating customer-value-based business strategies for competing in

18、the highest-value-added markets, that is, in what are today the most profitable, and the most competitive markets.Iteration. Just like the automotive industry, manufacturers often put new product models into market. With RP&M technology, it is possible to go through multiple design iterations wi

19、thin a short time and substantially reduce the model development time.3 Design Engineering Visualization. Conceptual models are very important in product design. Designers use CAD to generate computer representations of their design concepts. However, no matter how well engineers can interpret blue

20、prints and how excellent Some errors may still escape from the review of engineers and designers. The touch of the physical objects can reveal unanticipated problems and sometimes spark a better design. With RP&M, the prototype of a complex part can be built in short time, therefore engineers ca

21、n evaluate a design very quickly.Verification and optimization. Improving product quality is always a important issue of manufacturing. With the traditional method, developing of prototypes to validate or optimize a design is often time consuming and costly. In contrast, an RP&M prototype can be

22、 produced quickly without substantial tooling and labour cost. Consequently, the verification of design concepts becomes simple: the product quality can be improved within the limited time frame and with affordable cost. Iteration. Just like the automotive industry, manufacturers often put new produ

23、ct models into market. With RP&M technology, it is possible to go through multiple design iterations within a short time and substantially reduce the model development time.4Manufacturing We can use the RP&M prototype for producibility studies. By providing a physical product at an earlier d

24、esign stage, we can speed up process planning and tooling design. In addition,by accurately describing complex geometry, the prototype can help reduce problems in interpreting the blue prints on the shop floor. Another application is tooling development for moulds. The prototypes can also be used as

25、 master patterns for castings.Polyurethane bicycle tyres have gained popularity in recent yeas. A Calgary tyre manufacturing company is manufacturing such tyres using casting methods. In order to produce moulds for casting,a master tyre pattern must be first developed.The master pattern is used to p

26、roduce a temporary mould that produces a number of casting patterns.These casting patterns are then used to make the final moulds. After the moulds are manufactured, these patterns are also destroyed. However, the master pattern is preserved and it can be used again to produce casting moulds. The en

27、tire process including design, pattern development and mould manufacturing takes 6-8 weeks to produce a set of moulds.In order to reduce lead time and economically produce moulds, we have developed a computer-integrated design and manufacturing system and the rapid production technique of complex pa

28、tterns. The traditional method of making the master patterns uses machines to cut the initial rough shapes of the tyre patterns and complete other features by machining, then manually finishes the tread patterns. Because of the complexity of tread patterns of bicycle tyres, it usually takes days to

29、make such patterns and the quality is also a problem, especially the consistency of the tread patterns.According to the description of Cubital Ltd. , the machine can produce models with 0.1% (or 0. 002") dimensional accuracy in x,y and z directions. Cubital's CAD interface accepts both indu

30、stry-standard STL files and Universal files developed by Structural Dynamics Research Corp. (SDRC); the latter allows precise curve-fitting techniques to be used.5Conclusions Product features, quality, cost and time to market are important factors for a manufacturer to remain competitive. Rapid prototyping systems offer the opportunities to make products faster, and usually at lower costs than using convention