數(shù)控機(jī)床中英文翻譯資料-數(shù)控設(shè)計(jì)(存儲(chǔ)版)
【正文】 te their thinking to stay petitive. The inherent accuracy and repeatability of these machine tools have helped quality process tools such as statistical process control gain a foothold in machine shops. EVOLUTION OF THE NC/CNC MACHINE Numerical control is nothing new. As early as 1808 weaving machines used metal cards with holes punched in them to control the pattern of the cloth being produced. Each needle on the machine was controlled by the presence or absence of a hole on the punched cards. The cards were the program for the machine. If the cards were changed, the pattern changed. The players piano is also an example of numerical control. The player piano uses a roll of paper with holes punched in it. The presence or absence of a hole determined if that note was played. Air was used to sense whether a hole was present. The invention of the puter was one of the turning points in numerical control. In 1943 the first puter, called ENIAC (Electronic Numerical Integrator and Computer) was built. The ENIAC puter was very large. It occupied more than 1500 square feet and used approximately 18,000 vacuum tubes to do its calculations. The heat generated by the vacuum tubes was a constant problem. The puter could operate only a few minutes without a tube failing. In addition, the puter weighed many tons and was very difficult to program. ENIAC was programmed through the use of thousands of switches. The $15 calculator available today is much more powerful than this early attempt. The real turning point in puter technology was the invention of the transistor in 1948. The transistor was the replacement for the vacuum tube. It was very small, cheap, dependable, used very little power, and generated very little heat: the perfect replacement for the vacuu
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