高速重载行星滚柱丝杠滑滚界面摩擦行为与抗磨损研究

Because of the high power density, the planetary roller screw mechanism (PRSM) becomes the first choice of linear servo system instead of the ball screw. Compared with the same size of ball screw, the PRSM’s carrying capacity is six times larger. The straight-line velocity of nut could reach to 2m/s, and the acceleration could reach to 3g. In extremely demanding conditions that high speed, large load, high acceleration and loop start-stop, the PRSM would difficult to hold on the full film fluid lubrication state at the contact interface that it would easy to wear, which would influence its dynamic property as stability and lifetime. In this program, a dynamical model of PRSM in view of creep effect at the thread contact interface would be established, to get the mapping relation of friction moment, transmission efficiency and the stiffness. This program would study the dynamic characteristic and interface lubrication state coupling mechanism of PRSM in the loop start-stop working condition, and further on, uncover the transformation law of the wear development and performance degradation. The optimum design method of PRSM would be put forward base on the uniform loading optimization, hardness matching, and thread backlash control, which could be used to restrain the influence that thread wearing on the performance degradation. The results of this program would provide the technical support to the development and evaluation of PRSM with high-stiffness, low friction and high reliability, and the results of this program would be with important theoretical significance and application value.

行星滚柱丝杠具有高功率密度的特点，在高端装备中已逐步取代滚珠丝杠，成为直线伺服系统的首选零部件。与相同丝杆直径的滚珠丝杠相比承载能力提高6倍，螺母直线速度可达2m/s、加速度达3g。在高速、重载和高加速循环启停苛刻工况下，行星滚柱丝杠螺纹接触界面难以保持全膜流体润滑状态，极易发生磨损，影响其动态性能的稳定性和精度寿命。本项目建立考虑螺纹接触界面蠕滑效应的动力学模型，获得螺纹滑滚界面接触摩擦行为与摩擦力矩、传动效率和刚度的关联规律；研究高加速换向启停过程中行星滚柱丝杠动力学特性与界面润滑状态耦合作用机理，揭示螺纹接触界面磨损发展和动态性能退化的演变规律；提出基于均载优化、硬度匹配和螺纹副间隙控制的行星滚柱丝杠综合优化设计方法，抑制螺纹接触界面磨损对其动态性能退化的影响。为发展高刚度、低摩擦和高可靠性的行星滚柱丝杠和性能评价体系提供技术支持，具有重要的理论意义和应用价值。

随着装备制造业和国防工业的飞速发展，对直线伺服执行机构提出了高效高精度高可靠性的技术需求，行星滚柱丝杠以其独特结构和优异性能，得到了快速发展和应用，并逐步成为直线伺服机构的核心零部件。但是在高速、重载和高加速循环启停苛刻工况下，行星滚柱丝杠螺纹接触界面相对滑动速度和接触载荷存在波动，使其接触界面难以保持全膜流体润滑状态，极易发生磨损，影响其动态性能的稳定性，进而导致直线伺服执行机构的运转精度和服役寿命明显下降。本项目开展了高速重载行星滚柱丝杠滑滚界面摩擦行为与抗磨损研究，建立了考虑螺纹接触界面蠕滑效应的行星滚柱丝杠动力学模型，获得了螺纹滑滚界面接触摩擦行为与动态性能的关联规律；研究了换向冲击过程中工况条件和润滑剂流变性能对接触界面润滑状态转变的影响，揭示了行星滚柱丝杠动力学特性与界面润滑状态耦合作用机理；提出了行星滚柱丝杠综合优化设计方法，抑制螺纹接触界面磨损对其动态性能退化的影响。为提高行星滚柱丝杠运行稳定性和可靠性奠定了重要的理论基础。. 研究结果表明：丝杆转速对稳态时的摩擦力矩和效率无影响；摩擦力随横向和纵向蠕滑率的增大而非线性增大，横向切向力随着自旋率的增大而减小，纵向切向力随着自旋率的增大而增大。丝杆转速增大，油膜厚度随之增大，接触载荷比和接触面积比降低，润滑性能得到改善。负载增加和表面粗糙度增大，均导致油膜厚度降低，粗糙峰直接接触区域增大，摩擦系数增大，润滑性能变差，易造成磨损。丝杆转速、外载荷和磨损时间的增大均会导致螺纹接触区磨损量的增加；而磨损则会造成螺纹接触载荷的不均匀和波动程度加大；磨损时间和外载荷的增加导致螺纹螺距轴向偏差量增大，使得行星滚柱丝杠传动精度下降。. 在本项目资助下，发表学术论文9篇，其中SCI检索8篇、EI检索1篇；申请国家发明专利8件，已授权2件；培养硕士研究生3名，均已顺利毕业；研制了2个尺寸型号，共计4套试验样机。