Research on the dynamics of ball screw feed system with high acceleration

For the ball screw feed system with high acceleration, the large inertial force derived from the moving components may change the real contact state of the system kinematic joints, resulting in the changes of the contact stiffness and hence the dynamic characteristics of the feed system. In this study, an equivalent dynamic model of the ball screw feed system is established using lumped parameter method considering the influence of the acceleration. Equivalent axial stiffnesses of screw-nut joints and bearing joints are both derived based on the contact state due to the variation of inertial force. The experiments on the ball screw feed system driven with different accelerations are also performed to verify the dynamic model proposed. The variation of the contact stiffness of the kinematic joints, transmission stiffness and natural frequency of the feed system are discussed with acceleration and the results show that they all reveal sudden changes when acceleration reaches a certain value. Total load, rated dynamic load and screw tension force have a great effect on the system natural frequency at different accelerations. The largest acceleration the feed system can reach is determined by the smaller one of the two critical accelerations for nut joints and bearing joints.