A novel method to predict surface topography in robotic milling of directional plexiglas considering cutter dynamical displacement

Abstract

Recently, industrial robots have been applied to the machining of non-metallic materials because of the advantages of low cutting force requirements, low cost, and high flexibility, etc. Due to the limited static/dynamic stiffness of robot joints and links, the accuracy of robotic machining, especially the surface topography, is more susceptible to the cutting forces and dynamic vibrations, compared with CNC machining. To provide clear insights into the formation process of surface topography in robotic machining of oriented Plexiglas and choose reasonably the machining parameters, a method to predict the surface topography in the robotic machining of oriented plexiglas is presented, considering fully the tool dynamic vibrations. In this method, the dynamic intersection behavior in the cutting zones of the robotic machining process is first modeled, which is then used to determine the dynamic displacements. The gained vibration displacements are integrated into the sweep surfaces of the cutter cutting edges by changing the theoretical equations of cutting edges, in order to more accurately calculate the machining scallop points in the presence of tool vibrations. After that, between the discrete sweep surfaces and the workpiece, a mapping-based intersecting method is proposed to compute the intersections with the lowest scallop heights, and these intersections are used to construct the 3D graph, which can represent the topography of the resulting machined surface. Finally, the computer simulation and machining experiments are conducted, and it is shown that the predicted and physically measured surface topography have a good agreement.