Tool path adaption for compensation of thermal workpiece deflections based on virtual machining

In this paper, a method for the adaption of tool path to prevent temperature induced shape deviations is presented. A virtual machining simulation model is developed that includes material cutting, thermomechanical load and thermoelastic deformation simulation. A dexel based material removal simulation is extended by thermomechanical data and is linked to a FE-model for the calculation of the current thermomechanical workpiece state. A contact zone analysis is established to compute the workpiece load including the current deformation of the part. This thermomechanical load is discretized in the contact zone, so that individual heat sources and forces can be predicted depending on local cutting conditions like undeformed chip thickness or cutting speed. The contact zone analysis is extended by algorithms to calculate the currently generated shape error of the workpiece based on the extended thermomechanical data. Further, the information of the currently generated shape errors is used to find an optimal tool path with a minimum resulting shape error. Therefore, the dexel model is extended by a reference geometry as a target for the tool path optimization. A fast heuristic optimization algorithm is used for the fitting of the tool path. The presented approach leads to a significant reduction of the resulting shape deviations.