Application of Geometric Simulation for Determination of Dynamic Undeformed Chip Thickness in Milling

Abstract

Self-excited vibration is a significant constraint on productivity and production quality, which makes various forms of virtual machining widely used to find stable conditions before starting the actual machining operation. Numerical simulation of self-excited vibration, although much slower than analytical solutions, makes it possible to consider the nonlinearity of the process and its continuous variation. In 5-axis milling, predicting the instantaneous cross-sections of the uncut chip is very difficult, so geometric simulation is readily used to check the correctness of the NC program and the obtained shape of the workpiece. However, the known solutions take into consideration only programmed movements of the tool relative to the workpiece without considering vibrations, and those in which attempts have been made to consider vibrations have significant limitations. This paper uses a Geometric Simulator that determines the nominal positions of the tool relative to the workpiece, to which the displacements due to vibration, determined by the Dynamic Simulator, are added, making it possible to effectively determine the dynamic thickness of the cut layer and the trace on the workpiece material left by the vibrating tool. The use of geometric simulation, in which the material is represented by discrete voxels, introduces signal quantization, that is, the limited resolution of undeformed chip thickness and trace left on the machined surface. The paper presents the effect of voxel dimension on the accuracy of the simulation of self-excited vibrations