The Tool-path Trajectory Generation And Setup Optimization Of Workpiece Surface For Five-axis CNC Machine Tools

Five-axis computer numerical control(CNC)machining is one of the most effective methods for machining freeform surface parts,and it is widely used in aerospace,automotive and mold industries.Compared with traditional three-axis machining,fiveaxis CNC machining can simultaneously control the tool orientation and location,which can ensure the consistency of the surface machining process,and significantly improve the machining efficiency and accuracy.Since the real-time calculation in parametric curve interpolation is time-consuming and it is difficult to generate curved tool path,most freeform surface parts are machined with linear interpolation and the tool path is approximated by a large number of G01 segments in five-axis machine.However,due to the existence of the two additional rotary axis,there are nonlinear relationship between the workpiece coordinate system(WCS)and machine coordinate system(MCS),resulting the tool tip error and tool orientation error in G01 machining.These factors make it difficult for the five-axis machine to satisfy the characterization accuracy of the machining tool path.To cope with this problem,the following work is done:(1)Generalized kinematics modeling for five-axis machine tools.For three types of machine tools,the generalized kinematic model is established by using the homogeneous matrix.It includes forward kinematics from the WCS to the MCS and inverse kinematics from the MCS to the WCS.(2)Irredundant G01 path generation for five-axis machine tools.According to the given parameter surface,the theoretical tool path of the five-axis machine tool is generated based on the iso-scallop.For the theoretical path that has been generated,the tool tip error model and tool orientation model is proposed,and the irredundant G01 tool path generation method is developed;by using this method,the G01 tool path used in actual machining is generated according to the kinematics model of the five-axis machine tool.(3)The workpiece setup optimization for five-axis machine tools.For the G01 tool path which is stored with the form of cutter location(CL)data,a nonlinear error model is established based on the kinematics model of the five-axis machine tools,and the particle swarm optimization algorithm is used to optimize the workpiece setup,finally the local nonlinear error is controlled and the overall nonlinear error is minimized,therefore the surface quality of the part is ensured.(4)The simulation and experiment for five-axis machine tools.For the above part,Vericut software is used for simulation;the actual machining is carried out on the fiveaxis machining platform,which further proves the correctness and effectiveness of the proposed method.