A workpiece setup optimization method for 5-axis machining with motion coherence and stiffness enhancement

In 5-axis machining, the workpiece clamping setup, including the position and the orientation, can lead to significant performance differences, especially for complex curved workpieces. The current research usually only focuses on kinematic performance optimization to solve the singularity phenomenon and the incomplete accessibility of the machining space, failing to consider the machining motion mutation of both the rotary and linear axes, and ignoring the differences in machining stiffness performance of tool path corresponding to the different position and orientation when the workpiece setup changes. A workpiece setup optimization method for 5-axis machining with motion coherence and stiffness enhancement is proposed in this paper. The kinematic constraints for machining singularity avoidance and full accessibility of machining space are constructed, and the static stiffness analytical model and compliance matrix facing 3+2 machining space are established respectively. The motion coherence degree of the five axes and static stiffness deformation level of the machine tool during the machining process were considered as coupling objectives, and optimization was performed on the six (position and orientation) variables for curved workpiece setup. Through the simulation of blade machining on a vertical 5-axis machine tool with B-C tilting rotary table, the results show that the proposed method can reduce the incoherent degree of multi-axis motion by 25.96 %, and the cumulative stiffness deformation of the tool path consisting of 3575 cutter points is reduced by 3290 mu m. The machining motion coherence and stiffness performance and the machining quality of the workpiece surface are effectively improved.