Modeling And Analysis Of Motion Error Of Vertical Heavy Duty Machining Center

Vertical Heavy duty machining center plays an important role as a kind of typical heavy duty machine tools in the fields of shipbuilding, metallurgy and other heavy industry. However, there is still a great gap between the domestic products and the foreign advanced products in machining precision. As one of the most important actors that affect the accuracy of CNC machine tools, motion error is complicated and difficult to measure, related research has not formed systemly yet. Because of the vertical heavy duty machining center’s large mass, large load, long stroke and other characteristics, motion error influences it more obviously. Therefore, the main purpose of this article is to analyze the main factors affecting the motion error through establishing the servo feed system’s theoretical model of the vertical heavy duty machining center.According to the characteristic of large mass, large load, long stroke of vertical heavy duty machining center, establishing the theoretical model of the screw feed system in consideration of the effect of friction, backlash and the lateral displacement. The servo feed system theoretical model is established according to the three-loop servo drive model of 611 D driver of Siemens 840 D CNC system. Finally established the theoretical model based on the interference factor.of vertical heavy machining center servo system.Based on the theoretical model of the servo feed system, the single and double axis closed loop simulation model is built in Simulink. The pattern of how these factors influence the motion error is found out by simulation. Then analyze the influence of the main factors of motion error by simulation method.In order to verificaty the resultness of the theoretical model, appropriate verification experiment is designed. The validity of the theoretical servo drive model is verified through the comparison between the Bode diagram of theoretical servo drive model and the Siemens 840 D CNC system. The necessity of friction model is verified through the comparison of the critical crawling speed between the theory and experience. The correctness of the theoretical model of servo system is verified by comparing the result between motion error theoretical model simulation and measured.