Simulation of Thermomechanically Caused Workpiece Deformations for the NC Milling Process

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In the roughing process of NC milling, a significant amount of heat is introduced into the workpiece due to energy conversion during the chip formation process. This in turn leads to global thermo-mechanical deformations of the workpiece. These deformations remain present in the subsequent finishing process and may consequently cause strong deviations of the workpiece surface from its designed shape after cooling. As a result, critical fabrication tolerances may be exceeded.One aspect of this project is the compensation of the thermo-mechanical deformations introduced by the milling process. This is to be achieved through the use and extension of the hybrid simulation system developed in the previous two project phases. In order to enable multiple simulation series, the overall computation time required for a single simulation needs to be reduced. For this purpose, the simulation system must be augmented to allow an adaptive level of detail simulation with respect to the process state and requirements. To enable a more exact representation of the workpiece contours, the fictitious domain method must be extended to consider high order boundary descriptions. A further aspect to be investigated by simulation and experiment is the avoidance of introduction of heat into the workpiece by comparison of varying process parameter values and different milling strategies.In accordance with the overall goal of the priority program, the intent of this project is the development and validation of a method which, by avoidance of heat introduction and compensation of unavoidable thermo-mechanical workpiece deformation, computes an NC path that will yield the designed shape in the as-built part and remain within the specified fabrication tolerances.