Axial dynamic characteristic parameters identification of rolling joints in machine tool feed drive unit

In allusion to the problem that the existing methods for joint's parameters identification cannot accurately identify the dynamic characteristic parameters of rolling joints in assembled ball screw feed drive unit, a novel method to identify the axial stiffness and damping parameters of rolling joints was proposed. In the method, the screw was simplified as an elastic rod and the axial vibration equations of the feed drive unit under the excitation of harmonic force were derived, the identification model of the joints' axial stiffness and damping parameters was created, the identification equations were established based on measuring the distance between supporting points of the screw, the frequency and amplitude of harmonic exciting force, and the amplitude of axial vibration velocity at the screw end section, and then the axial stiffness and damping parameters of the rolling joints were identified by solving the identification equations using genetic algorithm. Taking a self-designed ball screw feed drive test bench as the research object, the axial stiffness and damping parameters of its ball screw assembly, and its left and right bearing groups were identified by using the proposed method, and the correctness of identified results was verified by experiments. The results demonstrate that the proposed method is correct and effective, and the absolute error of axial vibration velocity at screw end section between the calculated and tested values is within 7.7 μm/s, which achieves high identification accuracy. ©, 2015, Chinese Vibration Engineering Society. All right reserved.