Abstract: In the double five-axis mirror milling processes, due to the singular problems caused by the sudden change of the rotation axis, the surface processing quality and processing efficiency of thin-walled parts were reduced. Based on the analysis of the causes of the singularity problems, a method was proposed for optimizing the machining paths in the singularity regions. Based on the concept of C-space, under the boundary constraints of the singular areas, the tool axis vector in the mirror milling processes were kept perpendicular to the workpiece surface, and the alternative tool axis vector was determined by the minimum tool axis vector distance, the tool axis vectors in the singular region was locally corrected. Then, B-spline curve fitting was performed on the entire processing path, and an optimization model was established based on the minimum parameter curve strain energy. By adjusting the parameter curve, the smoothness of the path was improved, the processing efficiency was ensured, and the processing quality was improved. Finally, the effectiveness of the proposed method was verified through simulation experiments and actual machining results. The results show that minimum wall thickness error is reduced by 50%, the maximum wall thickness error is reduced by 75%, and the overall wall thickness error range is reduced by 68.75%. At the same time, the complete path processing time is decreased by 2.1%.

Key words: mirror milling machining, singular problem, tool axis vector, path optimization

摘要： 在双五轴镜像铣削加工中，由于旋转轴运动突变带来的奇异问题，导致薄壁件表面加工质量以及加工效率降低。在分析奇异问题产生原因的基础上，提出一种奇异区域加工路径优化的方法。基于C-空间的概念，在奇异区域边界约束条件下，同时满足镜像铣削加工中刀轴矢量与工件表面保持垂直，以最小刀轴矢量距离确定备选刀轴矢量，对奇异区域的刀轴矢量进行局部修正。然后对整条加工路径进行B样条曲线拟合，基于最小参数曲线应变能建立优化模型，通过对参数曲线的调整，提高路径的光顺性，保证加工效率，提高加工质量。最后，通过仿真实验和实际加工结果验证所提方法的有效性。研究结果表明，最小壁厚误差减小50%，最大壁厚误差减小75%，整体壁厚误差范围缩小了68.75%，同时完整的路径加工时间缩短了2.1%。

关键词: 镜像铣削加工, 奇异问题, 刀轴矢量, 路径优化