谐波齿轮大变位柔轮滚齿误差分析及滚刀设计

Hobbing Error Analysis of Harmonic Gear Large Modified Flexspline and Hob Design

基于滚齿仿真计算研究大变位柔轮成形机制,分析其齿面理论加工误差值及产生原因,重新设计滚刀以提高大变位柔轮滚齿精度。建立滚刀系列切削刃参数方程,根据滚刀与工件的几何参数及加工参数确定滚刀与工件相互位置和空间运动关系,进行滚齿切削仿真;根据滚刀多刃切削的成形特点,建立齿面理论加工误差评价模型,对滚齿误差进行仿真计算;基于滚齿加工时滚刀与齿轮法向基节相等原理,重新设计滚刀以减小滚齿齿面偏差。研究发现,标准滚刀加工齿数较多的大变位柔轮时,会因滚刀切削刃数不足而在齿顶处出现欠切削,致使加工误差大;模数、压力角不同于标准滚刀的新滚刀仅需较少切削刃即可实现大变位柔轮的完全切削,且齿面加工误差比标准滚刀完全切削齿面时产生的加工误差略小。研究结果可为大变位柔轮滚齿精度控制研究及滚刀参数选择等提供重要参考。

The forming mechanism of large modified flexspline is studied based on hobbing simulation cal⁃culation,the theoretical machining error of tooth surface and its causes are analyzed,and the hob is redesigned to improve the hobbing accuracy of large modified flexspline.The parameter equation of a series of hob cutting edges is established,the mutual position and spatial motion relationship of the hob and the workpiece are deter⁃mined according to the geometric parameters of hob and workpiece and machining parameters,and the gear hob⁃bing simulation is carried out.According to the forming characteristics of hob multi-edge cutting,the theoretical machining error evaluation model of tooth surface is established to simulate the hobbing error.The hob is rede⁃signed based on the principle that the normal base pitch of hob is equal to that of gears during hobbing to reduce the hobbing tooth surface error.It is found that the tooth profile error near the tooth top will be large when the standard hob is used to machine the large modified flexspline,because the number of cutting edges of standard hob is insufficient and the tooth top will be under-cut;the new hob which module and pressure angle are differ⁃ent from that of the standard hob can realize the complete cutting of each tooth of large modified flexspline with only a few cutting edges,and the machining error of the tooth surface is smaller than that of the standard hob when the tooth surface is completely cut.The research results can provide important reference for the study of hobbing accuracy control of large modified flexspline and the selection of hob parameters.