摆线轮轮廓高速周铣工艺系统的弹性铣削力预测方法

Modeling Methodology of Flexible Milling Force for Cycloid Gear on High Speed Peripheral Milling Process System

为了提高高速铣削过程中复杂薄壁结构件的加工精度,针对高速铣削摆线轮轮廓的工艺特点,建立摆线轮刚性轮缘和弹性轮缘的铣削力模型。该模型基于弯扭耦合弹性力学理论,建立薄壁轮缘的铣削变形模型;并结合周铣摆线轮轮廓时曲率沿路径连续变化的特点,基于工件—刀具的铣削变形,建立工艺几何模型;在此基础上推导出切削啮合角和瞬时切削厚度的表达式,采用改进的Newton-Raphson迭代算法,仿真出铣削摆线轮轮廓的铣削力。研究表明工件和刀具共同引起的径向综合变形是工艺系统变形的主要因素,并引起铣削力的变化;随着轮廓形状呈现周期性的变化,对应于摆线轮轮廓上的每齿进给量也呈现周期性的变化,使得铣削力呈现周期性变化。最后,经铣削试验验证,实测结果和仿真结果具有较好的一致性。

To improve the machining accuracy of complex thin-walled structural components during high speed milling process, a flexible force model suitable for both thin-wall tooth profile and rigid tooth profile of cycloid gear is proposed. The model is based on identifying key processing characteristics that influence deflection of low-rigidity process system. Based on the application of bending-torsional coupled theory, a new mathematical model suitable for static machining deflection prediction of thin-walled tooth profile is proposed due to bending deflection and shear deflection. Taking into account the deflections of workpiece and cutter the expressions are derived for process geometries parameters in peripheral milling where curvature varies continuously along the tool path. Then modified cutting teeth immersion angle and undeformed chip thickness are introduced due to the deflections and process geometries. In machining workpiece geometries, the milling force distribution for thin-wall tooth profile of cycloid gear is solved by the modified Newton-Raphson iterative algorithm. Researches indicate that the milling forces are influenced strongly by workpiece-cutter defection in the radial direction and vary periodically along the cutting profile. This is attributed to the periodic variation of gear profiles and feed per tooth along the gear tooth path. Finally, the force model is experimentally validated and the results show good consistency between predicted and measured deflection values.