关键词: 五轴加工, 奇异问题, 刀轴矢量, 非线性误差, 样条插补

Abstract: Tool orientation is very complicated for the 5-axis machining.At the singularity point of a 5-axis machine,there is no solution to the inverse kinematics when the post-processing is performed by CAM software,which leads to acute change of rotation axis.As a result,the non-linear error increases while the machining quality decreases.By taking a Table (C-axis)-tilting (A-axis) 5-axis machine as an example,the C-axis rotation was proved to be the reason of the singularity problem by studying the tool axis movement.Then a novel k-value method of cutter location data was proposed for detecting whether the tool axis vector is located in singular region.A scheme based on tool axis vector planar interpolation and spline curve fitting to control non-linear error was also proposed.Through the S surface test,the proposed method was demonstrated much better than the linear interpolation.Experiment results showed that the non-linear errors in singularity area declined significantly,the surface was smoother and the machining accuracy and efficiency were also improved.

Key words: five-axis machining, singularity, tool axis vector, non-linear error, spline interpolation