| NC machine tools is the integrated products of typical electromechanics collecting mechanical manufacturing technology and computer, hydraulic pressure, measure sensing, information processing, optical-mechanical-electrical integration,etc. technologies in an organic whole. It has well solved the processing problems of complex shape and structure,high precision,small batch and changeable parts,and can stabilize the processing quality of the products, reduce worker's labour intensity, improve production efficiency by a large margin. The engineering level of NC machine tools and owning amount have already become one of the important signs of weighing a national industry's modernized level. About 4 million of total amount of the machine tools at present of our country,of which a total of NC machine tools are only 200,000 sets. Our enlistment age 10 years over the machine total of 60%,and the enlistment age to 10 years of machine tools,automatic / semi-automatic machine tools less than 20%.Such equipments are used for processing the products prevalence of poor quality, lack of variety and high cost,availability such a long period, therefore is uncompetitive on world and domestic markets.For enterprises,relying solely on the purchase of new NC machine tools,a large initial investment required,resulting in many enterprises,especially small and medium-sized private enterprises felt helpless.If carrying on the NC transformation to the old machine tools, it is with little investment, with instant effect, is an effective way of improving numerical control rate of our country in a short time.This subject comes from the common lathe numerical control transformation project of Ningbo technical school. This thesis has explained thought and method of NC transformation of CA6140 common lathe from machinery and electric two respects on the basis of summarizing state of development of NC technology. The full thesis is divided into six chapters, the main contents of every chapter is sketched as follows:Chapter one, introduction part, has mainly explained development trend, history and current situation of NC machine tools in China,and then has explained the significance of NC transformation, significance of selected topics and the contents of research.Chapter two, has mainly explained the overall scheme of NC transformation. Expounding the spindle pulse encoder on the installation, anti-backlash gear structure, automatic tools rest and the choice of NC system.Chapter three, has mainly described the characteristics of SINUMERIK 802S base line NC system, electric cupboard design, power and grounding for attention, connection of every part of NC system and the interface design of PLC,the selection of the frequency converter of spindle and the design of main control circuit.Chapter four, has mainly explained the calculation of cutting force on the turning and facing, the calculation and selection of vertical and horizontal ball screws, the design of vertical and horizontal deceleration gears and the calculation and selection of stepper motors,etc.Chapter five, has explained PLC and lathe parameters setting and the test of geometirc, positioning and cutting precision after transforming and has compared with the machining accuracy of the lathe before transforming through processing a working shaft.Chapter six, has done the summary to the full thesis and has looked into the distance to subsequent research work.The transformed lathe had been put into the Industrial Training Center of our school and has run over two years, the machining accuracy is high, size consistency is good, performance is steady, has not presented the great trouble, has made the great technological economic benefits.
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