行星滚柱丝杠螺纹副-齿轮副同步啮合动态接触载荷特性

Dynamic Contact Load Characteristics of Synchromesh Between Screw Pair and Gear Pair in the Planetary Roller Screw

为揭示行星滚柱丝杠螺纹副-齿轮副同步啮合动态接触载荷特性,采用有限元方法建立了行星滚柱丝杠数值模型。根据行星滚柱丝杠运动原理,推导了螺母轴向速度和位移理论计算公式,并给出了螺纹牙静载荷分布模型,分别从运动学和静动载荷的角度将数值结果与理论值进行了对比,相对误差均小于5%,从而验证了模型的正确性。基于数值模型,分析了不同螺母负载、丝杠转速、摩擦系数对行星滚柱丝杠各接触副动态接触载荷的影响规律。研究结果表明:丝杠转速增大,各接触载荷曲线波动增大,同时齿轮副和滚柱轴端与保持架接触载荷曲线波动周期性减小;螺纹副稳态接触载荷受螺纹副-齿轮副同步啮合及齿轮副啮合激励的共同影响呈现微幅波动;螺母负载增大,除齿轮副外各接触副接触载荷成正比增加,其中螺纹副和保持架分担了齿轮副部分载荷,导致齿轮副接触载荷减小;摩擦系数增大,接触载荷增幅明显,且各接触载荷曲线波动变大。

A numerical model of planetary roller screw is established by using the finite element method to reveal the dynamic contact load characteristics of synchromesh between the thread pair and gear pair in the planetary roller screw.According to the motion principle of planetary roller screw,the theoretical calculation formulas of the axial speed and displacement of nuts are derived,and the static load distribution model of thread tooth is provided.The numerical results are compared with the theoretical values in terms of kinematics and static loads,and the relative errors are both less than 5%,which verifies the correctness of the model.Based on the numerical model,the influence of different nut loads,screw speeds and friction coefficients on the dynamic contact load of each contact pair of planetary roller screw is analyzed.The results show that the fluctuation of contact load curves increases with the increase of screw speed,and the fluctuation of contact load curves between gear pair and roller shaft end and cage decreases periodically.The steady state contact load of the screw pair fluctuates slightly under the influence of the synchromesh of thread pair and gear pair and the meshing excitation of the gear pair.As the nut load increases,the contact load of all contact pairs(but the gear pair)increases in direct proportion.The thread pair and the cage share partial load of the gear pair,leading to the reduction of the contact load of the gear pair.As the friction coefficient increases,the contact load increases obviously,and the fluctuation of each contact load curve becomes larger.