A novel surface topography prediction method for hybrid robot milling considering the dynamic displacement of end-effector

Abstract

Abstract There are extremely high requirements for the surface quality and integrity of parts in the automotive, aerospace and die/mold industry. Meanwhile, due to the advantages of large workspace, strong flexibility and low cost, the hybrid robots have shown broad application prospects in the above fields of machining or manufacturing. However, limited by the stiffness of robot joints and links, the surface topography of milled workpiece is more susceptible to the dynamic response caused by the variation of robot postures and cutting forces. The simulation of the surface topography in the robotic milling process remains a challenging goal. This paper focuses primarily on the dynamic displacement of end-effector for the TriMule hybrid robot as well as its impact on the topography of milled surface. In this paper, a framework model for predicting the topography of milled surface is developed first, and then further perfected by incorporating the dynamic displacement of the robot-tool system in the machining process. In this method, the dynamic model of the robot milling process is developed based on the stiffness of the TriMule hybrid robot within the entire workspace. After that, the finite element method is introduced to discretize the tool and workpiece, and the topography of the milled surface can be regenerated through the Boolean operations and the Z-MAP method. Finally, a series of validation experiments are conducted and the results indicate that the proposed model can be used to predict the topography of the surface milled by the hybrid robot in different postures.