凸凹接触式行星滚柱丝杠的啮合承载特性

Meshing and bearing characteristics of convex-concave contact planetary roller screw mechanism

摘要:

为提高行星滚柱丝杠的承载能力,分析优化行星滚柱丝杠的螺纹牙型,提出一种基于凸凹接触的啮合方式。设计凹圆弧的丝杠和螺母牙型轮廓,基于空间啮合理论推导螺纹曲面方程、空间啮合方程,并基于赫兹接触理论和变形协调方程建立负载分布模型；采用数值计算的方法对啮合点位置、轴向间隙和接触应力进行求解,系统揭示了牙侧角、螺距等参数对啮合点位置、轴向间隙和负载分布的影响规律,并对比分析标准式和凸凹式行星滚柱丝杠的接触应力。结果表明:牙侧角对轴向间隙的影响最大,丝杠和螺母的凹圆弧半径变化对接触点位置和轴向间隙几乎没有影响,但对承载能力影响十分明显；与标准式相比,凸凹接触式行星滚柱丝杠的承载能力有较大的提高,丝杠和螺母凹圆弧半径越小承载能力提高越明显。本研究为研制高承载、高使用寿命的行星滚柱丝杠提供了优化设计和分析的依据。

Abstract:

This paper optimizes the thread profile of the planetary roller screw mechanism to improve the bearing capacity of the planetary roller screw mechanism. A meshing method based on convex-concave contact is proposed and the thread profile of screw and nut with a concave arc is designed. Based on the space meshing theory, the thread surface equation and the space meshing equation are derived, and the load distribution model is established based on the Hertz contact theory and the deformation coordination equation. The contact point position, the axial clearance and the contact stress are calculated by the numerical calculation method, and the law of the flank angle, pitch and other parameters on the contact point position, the axial clearance and the load distribution are revealed systematically. The contact stress between the standard and the convex-concave contact planetary roller screw mechanism is compared. The results show that the flank angle has the greatest influence on the axial clearance. The changes of the concave arc radius of the screw and nut make little difference to the contact point position and the axial clearance, but have a great impact on the bearing capacity. The bearing capacity of the convex-concave contact planetary roller screw mechanism is greatly improved compared with the planetary roller screw mechanism. The smaller the concave arc radius of the screw and nut, the more obvious the improvement of the bearing capacity. This research provides a basis for optimal design and analysis for the development of the planetary roller screw mechanism with high load capacity and long service life.