基于运动学分析的行星滚柱丝杠副应力循环规律

The movement and force transmission of planetary roller screw mechanism (PRSM) are realized by the planetary motion of multiple rollers and the meshing of their helical surfaces between the screw and the nut. Based on the characteristics of spatial helical surface of screw, nut and roller, the kinematic analysis model of PRSM is established by using the parametric equations of the screw, nut and roller in this paper. The positions of contact points are obtained according to the principle of continuous tangency. Then, the relationship between the structural parameters of PRSM is deduced from the kinematics characteristics of the contact points. On this basis, the spatial motion trajectories of the screw, nut and roller are simulated, and the stress cycle behaviors on their threads are further obtained. Furthermore, the working life of the PRSM is predicted. The results show that there is a relative velocity at the contact point of the screw and roller, and the contact point of the nut and roller is the instantaneous center; and that each specific contact point on the roller and nut bears stable pulsating cyclic contact stress, while each specific contact point on the screw is subjected to cyclic contact stress with periodic amplitude variation.