볼나사 이송계의 동적 최적 설계에 관한 연구
(A) Study on Dynamic Design Optimization of a Ball Feed Drive System
볼나사 이송계 진동해석 최적 설계;
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Recent trend in machine tools is pursuing the high precision and high speed facility. But during high-speed running of machine tools, serious vibrations may occur in their feed-drive systems. Therefure, it is necessary to reduce vibrations of faed-drive systems in order to increase the high precision positioning accuracy in machine tools. In this paper, we analyze the dynamic characteristics and vibrations of a ball screw feeding drive system and perform its dynamics parameter design optimization using genetic algorithm. Prior to design optimization, a ball screw drive system has been mathematically modeled as a 6 degree-of-freedom model (2 rotational motions plus 4 translational motions), whose natural frequency and modeshapes are calculated. Furthermore, its transient vibrations due to a specific motor speed control input are analyzed by MATLAB Simulink. In the design optimization, design variable includes the moment of inertia of ball screw, mass of nuL stiHness and damper of ball screw, stiffness and damper of nut stiffness of motor mounting panal. The unique objective function is obtained by weighted multi-objective functions, such as maximum amplitude, RMS of displacement, overshoot, and settling time. The constraint are maximum critical speed limit and maximum head vibration limit. Optimization result showed all the maximum amplitude, RMS displacement overshoot, and settling time have been reduced after optimization.