Study on the meshing theory of the ring-shaped roller screw mechanism

环形牙滚柱丝杠啮合机理研究

Received: 1 September 2022

Abstract

Based on the structural characteristics of ring-shaped roller screw mechanism (RRSM), helical equations of the screw, roller and nut are derived. Meshing equations at the screw-roller and nut-roller interfaces are developed, which can be used to calculated contact positions of thread teeth. The equations of axial clearances in the RRSM are also derived and zero-clearance design values of the thread thicknesses are given. By comparing the contact positions and clearances obtained from a previously published numerical model, the feasibility of the proposed model is validated. The influence of structural parameters on the meshing characteristics of the RRSM is analyzed. When the nominal radius of the screw is increased or that of the roller is decreased, the contact point at the screw-roller interface will move towards to the tangential-point of pitch circles. The difference between the value of the screw flank angle and that of the screw flank angle has great influence on contact positions. When the values of the nut and roller flank angles are equal, the contact points will lie on the tangential-point of pitch circles and the zero-clearance design value of the thread thickness at the nut-roller interface is equal to the half of the screw pitch. The radius of the roller thread profile has little influence on the zero-clearance design values of thread thickness.

摘要

基于环形牙滚柱丝杠结构特点, 推导了丝杠、滚柱和螺母的曲面方程, 建立了计算丝杠和滚柱以及螺母和滚柱之间接触位置的啮合方程, 给出了环形牙滚柱丝杠的轴向间隙计算公式和零间隙牙厚设计量。通过与现有数值模型接触位置和间隙计算结果的对比, 验证了所建模型的正确性, 分析了结构参数对环形牙滚柱丝杠啮合特性的影响规律。分析结果表明: 较大的丝杠名义半径和较小的滚柱名义半径有利于接触点接近两零件中径切点位置; 丝杠和滚柱的接触位置对两零件的牙侧角差值十分敏感; 当螺母和滚柱牙侧角相同时, 接触点位于两者的中径切点且零间隙牙厚设计量等于螺距的一半; 滚柱牙型轮廓半径对丝杠和滚柱的零间隙牙厚设计量几乎无影响。