Effect of the Stiffness of the Turntable Bearing Joint on the Dynamic Characteristics of the Five-Axis Machine Tool Rotary System

Abstract

The positioning accuracy and machining performance of the five-axis machine tool are significantly impacted by the dynamic characteristics of the rotary system of the two-axis rotary table machine. In this study, first, the stiffness of the joint bearing of the rotary table system is calculated, and the effect of bearing clearance and external load on the stiffness is analyzed. Second, considering the stiffness characteristics of the joint, the natural frequency and mode shapes of the turntable system are calculated. Finally, the influence of turntable angle and bearing stiffness on the dynamic characteristics of the turntable system is analyzed. The results show that the natural frequency of the rotary table system does not change obviously with the axial stiffness of the turntable bearing joint, but increases significantly with the increase in the radial stiffness. The first order natural frequency of the turntable decreases with the increase in the swing angle, and the change in the first order natural frequency is 77.43 Hz. The research results provide theoretical basis and guidance for machine tool design and use.