| Summary: | This thesis presents a novel geometric modeling methodology of cutter-workpiece engagement extraction for general milling processes. Cutter-workpiece engagement (CWE) geometry is the instantaneous contact area between the cutter and the in-process workpiece. It defines how the cutting edge enters and exits the workpiece. It plays a crucial role for process simulation and directly effects the calculation of cutting force, torque and et cetera. Based on the result of physical simulation, the milling process can be optimized and the machining performance can be improved. Successful optimization depends on the accuracy of the extracted CWE.
The difficulty and challenge of CWE extraction comes from various types of cutters, changing geometry of in-process workpiece and multi-axis tool path of cutter movement. Existing methods confront difficulty to be available for general milling processes, which means for any type of cutter, any shape of in-process workpiece and any tool path, even with self-intersections. To fulfill the requirement of generality, this thesis proposes to model all geometries as triangle meshes throughout the simulation and certain strategy of CWE extraction is applied. Our methodology adopts ball pivoting algorithm for cutter swept volume generation. Octree space partition method is applied to speed up triangle-to-triangle intersection calculation which is used for Boolean operation between meshes. The reported method has been tested on several case studies of different complexity. The effectiveness of the proposed methodology shows its potential for further applications.
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