Improving the dynamics of five-axis machining through optimization of workpiece setup and tool orientations

Existing works in optimization of five-axis machining mainly focus on the machining efficiency and precision, while the dynamic performance of the machine tools has not been fully addressed, especially in high-speed machining, in which the rotary actuators have limited dynamic ability. In this paper, a study is reported on how to generate a tool path so that the maximal angular accelerations of the rotary axes of the five-axis machine can be reduced. Two independent methods are proposed for this task: (1) by optimizing the setup of the workpiece on the machine’s table, and (2) by finding better tilt and yaw angles for the tool orientations. In this paper, the setup parameters of the workpiece are incorporated into the inverse kinematic equations, and angular acceleration functions are established according to the numerical solutions of those equations. While varying the tool orientations unquestionably would affect the surface quality of the machining, we introduce the so called Domain of Geometric Constraints that will restrict the allowable tilt and yaw angle of the tool at the cutter contact points on the part surface, so to ensure the satisfaction of the requirement of both local-gouging-free and cusp-height. For the first method–finding the optimal workpiece setup–a heuristic-based approach, i.e., the Genetic Algorithm (GA), is adopted, whereas for the second method–the constrained optimization of tool orientations–we present an elaborate algorithm based on the results from the analysis conducted by the authors. At the end of the paper, computer simulation experiments are reported that demonstrate the effectiveness of our proposed methods and algorithms.

► Kinematic model and inverse dynamic solutions of specific five-axis machines. ► Efficient methods for improving dynamic performances of machine’s rotary axes. ► Optimal workpiece setup to improve the dynamics for a same tool path. ► Tool orientation optimization to improve the dynamics of the five-axis machine. ► Preliminary experiments showing potential of the proposed solutions.