外文翻译文献翻译CADCAM的发展精选.docVIP

The Evolution of CAD/CAM Introduction Given the fact machine tool automation really began only with the development of numerical in the 1950s-less than 40 years age- it is amazing that there exist today manufacturing plants that are almost completely automated. Granted, these installations produce relatively few varieties of product, but it is clear that the physical components for a sophisticated automated enterprise are available. Before beginning to discuss these capabilities, we must identify what we will mean by “manufacturing plants” in this book, since there are several categories of manufacturing (or production) that could be considered. We will consider manufacturing in three broad areas (1) continuous-process production, (2) mass production, and (3) job-shop production. In an even broader classification, the latter two categories could be considered as discrete-item production. Continuous-process Production product that flows in a continuous stream falls into this manufacturing category. Typical processes include petroleum, cement, steel rolling, petrochemical, and paper production, as well as many others. An obvious attribute of these is that the production equipment is utilized for a relatively small group of similar products. Combining this attribute with the continuous-flow characteristic allowed investment in automated equipment that realized benefits well before such advantages were seen in the other two categories of production. This text will not be oriented toward continuous-process production, though. This text will not be oriented toward continuous-process production, though many of the topics will be as germane to this category as to other two. Mass production This entails the production of discrete units of production at very high rates of speed. Discrete-item production is used for such goods as automobiles, television sets, refrigerators, electronic components, and so on. Mass production attempts to emulate the characteristics of conti