计算机辅助设计外文翻译---cadcam的应用范围(编辑修改稿)

计算机辅助设计外文翻译---cadcam的应用范围(编辑修改稿)内容摘要：

e the part geometry dictates the machining required, kno,ing the part shape can allow for (semi)automatic partprograrn preparation. CAD data can also be used for automated process planning. It is interesting to note that twenty years ago if a part of reasonable geometric and manufacturing sophistication was created, hundreds of design and drafting hours would be required. After the part was specified, marlufacture would begin. ll1is planning would normally require some minor design changes (back to the designer and draftsman), and might take as long as the original design process. Special tooling, fixturing, etc., might also be specified during the plarming for manufacture. In all, the entire process of product and process design could take several weeks or months. With today39。 s CAD systems, designing (againg a rea.39。 \onably sophisticated ponent) and generating manufacturing plans, preparing paIt programs and producing the pm is possible in days rather than weeks. In general, the tatal en!?ineering aI1d manufacturing time has been markedly using integrated CAD/CAM methodalogies. 2 Computer Aided lVIanufacturing The scientific study of metalcutting and autamatian techniques are pnxlucts af the twentieth century. Two. pianeers of these techniques were Frederick Taylar and Henry Ford. During tl1e early 1900s, the improving U. S. standard af living brought a new high in penlOnal wealth. 39。 Ille majar result wa。 the increased demand far durable goods. This increased demand meant that manufacturing cauld no. longer be treated as a blacksmith trade, aIld the use af scientific study was emplayed in manufacturing analysis. Taylar pianeered studies in scientific ITlaI1agement in which methods far productian by both men and machines were studied. Taylar also condueted meatalcutting experiments at the Midvale Steel Campai1y that lasted 26 yeaIS and produced 400 tans af metal chips. The result af Taylar39。 s metalcutting experiments was the develapment af the Taylar toollife equation that is still used in industry today. This toollife equatian is still the basis af detennining ecanamic metal cutting and has been used in adaptive canhulled machining. Henry Ford39。 s contributions took a different turn from Taylor39。 s. Ford refined and developed the use of assembly lines for the major ponent manufacturer of his automobile. Ford felt that every American family sh~d have an automobile, and if they could be manufactured inexpensively enough then every family would buy one. Several mechanisms were developed at Ford to acmodate assembly lines. The automation that Ford developed was built into the hardware, and Ford realized that significant demand was necessary to offset the, initial development and production costs of such systems. Although manufacturing industries continued to evolve, it was not until the 1950s that the next major development occurred. For some time, strides to reduce human involvement in manufacturing were being taken. Speciality machines using carns and other hardwired logic controllers had been developed. The U. S. Air Force recognized the development time required to produce this special equipment and that the time required to make only small sequence changes was excessive. As a result, the Air Force missioned the Massachusetts Institute of Technology to demonstrate programmable or numerically controlled (NC) machines (also knO\\l1 as softwired machines). With this first demonstration in 1952 came the beginning of a new era in manufacturing. Since then, digital puters have been used to produce input either。