Abstract: The active design of PRSM tolerance was essential to improve the transmission performance and processing feasibility. A PRSM travel error and axial clearance model was established by integrating the thread coaxiality errors, pitch errors and mid-diameter errors of the screw, roller and nut, and the sensitivity index of each error factors was calculated. Based on the expert judgment hierarchical analysis method of triangular fuzzy number, processing weights, and initially assigning the tolerance of each error terms of PRSM travel accuracy were calculated. The tolerances of each error terms of axial clearance tolerances were optimized based on the sequential quadratic programming algorithm. And the effectiveness of the method was verified by taking the standard PRSM as an example. The results show that the method of optimizing the tolerances of each error terms for the stroke accuracy and axial clearance balances the stroke accuracy and axial clearance extremely well, and relaxes the width of the key tolerance zones, which improves the machining feasibility of the parts. The example shows that after optimization, the minimum value of axial clearance in the complete cycle is changed from -25 μm to 0 to avoid thread interference; after optimization, the amount of V300 stroke variation is basically unchanged, and the width of tolerance zone is increased by 65% on average, which ensures PRSM grade 5 accuracy index, improves the machining feasibility of key parts, reduces machining costs and may provide reference for PRSM tolerance active design theory.

Key words:  , planetary roller screw mechanism(PRSM), tolerance matching, machining error, itinerary accuracy, axial clearance

摘要： 行星滚柱丝杠（PRSM）公差主动设计对提高其传动性能与加工可行性有着至关重要的作用。建立了综合考虑丝杠、滚柱、螺母的螺纹同轴度误差、螺距误差与中径误差的PRSM行程误差及轴向间隙模型，计算得到各误差因素敏感性指数；基于三角模糊数的专家评判层次分析法，计算各误差因素加工权重，初步分配PRSM行程精度各误差项公差；基于序列二次规划算法对轴向间隙各误差项公差进行优化；以标准型PRSM为例，验证了该方法的有效性。结果表明：针对行程精度与轴向间隙各误差项进行公差优化的方法，不仅极好地平衡了行程精度与轴向间隙，且增加了关键公差带宽度，提高了零件加工可行性，算例表明，优化后完整周期内轴向间隙最小值由-25 μm变为0，避免螺纹干涉发生；优化后V300行程变动量基本不变，公差带宽度平均增加65%，保证PRSM 5级精度指标的同时提高了关键零件加工可行性，降低了加工成本，可为PRSM公差主动设计理论提供参考。

关键词: 行星滚柱丝杠机构, 公差匹配, 加工误差, 行程精度, 轴向间隙