Studies on meshing clearance of thread pairs of planetary roller screw mechanism in different directions

不同方向上行星滚柱丝杠螺纹副啮合侧隙研究

Shaanxi Engineering Laboratory for Transmissions and Controls, Northwestern Polytechnical University, Xi'an 710072, China

Received: 16 May 2023

Abstract

The helix surface model of planetary roller screw mechanism (PRSM) is established by utilizing the parametric equations of space surface according to the structural features of screw, roller and nut. The helix surface model of PRSM is improved in consideration of the PRSM assembly relationship. The normal vector equations of helix surfaces are obtained based on the helix surface model. The meshing clearance models of PRSM in axial, radial and circumferential directions are built considering the movement direction of parts utilizing surface meshing conditions. The influence of structural parameters on the meshing clearance of PRSM is also analyzed. The results show that the meshing points between the roller and the screw in three directions are not in the middle diameter. The meshing points in the three directions of the roller and the nut are in the middle diameter of the roller. The pitch, tooth angle and tooth thickness of the thread all have an influence on the meshing clearance of PRSM. Only by increasing the tooth thickness of the thread can the meshing clearance in the three directions be reduced at the same time. The pitch and tooth angle should be selected properly to meet the practical requirements.

摘要

根据丝杠、滚柱以及螺母结构特征, 利用空间曲面参数方程分别建立了行星滚柱丝杠各个零件的螺旋曲面模型, 并结合行星滚柱丝杠装配关系, 得到行星滚柱丝杠空间啮合曲面方程。在此基础上, 获得螺旋曲面法向量, 基于曲面啮合条件, 考虑零件运动方向, 建立了行星滚柱丝杠在轴向、径向以及周向上的啮合侧隙模型, 并讨论了结构参数对行星滚柱丝杠啮合侧隙的影响规律。结果表明, 滚柱与丝杠侧在3个方向上的啮合点均不在螺纹中径, 滚柱与螺母侧3个方向上的啮合点均在滚柱螺纹中径位置; 螺距、牙侧角以及螺纹牙厚均对行星滚柱丝杠啮合侧隙有影响, 只有增大螺纹牙厚才能同时减小3个方向上的啮合侧隙, 螺距和牙侧角应根据实际需要选择合适的参数。