Triple-ray-rep model based geometric modeling simulation with voxelized removal volumes in NC machining

Abstract

Geometric modeling techniques presented in this study target the important problem of improving the quality of milling processes through simulation-assisted research and development. Geometric modeling capabilities include generating the tool swept volumes for each tool motion, subtracting these from a dynamically changing in-process workpiece model, and calculating the instantaneous cutter engagements. In this study, the workpiece has been represented with a series of evenly distributed vectors oriented in three directions of the Cartesian coordinate system. Thus, sampling in multiple directions, called the triple-ray rap-based method, overcomes the problems associated with z-Map-based techniques, in which sampling only along one direction misses surface portions such as sharp edges and vertical walls. In addition, since the tool-swept volumes are regarded as envelope surfaces in the vector model-based techniques, the intersection calculations have been reduced to line/surface intersections. In the tool engagement extractions, the tool removal volumes represented by the vectors have been utilized instead of the in-process workpiece to reduce memory usage and the program runtime. Later, these removal volumes were voxelized at the predetermined resolutions for performing the arc and voxel intersections. In this research, the milling tools have been modeled as the surface of revolutions. Thereby, the method has been broadened to use more than just the APT type cutters, and it can be generalized for other types of cutting tools.

Keywords

• Triple-ray rep model
• Voxel-based tool engagements
• Indirect workpiece update
• 3+2 axis NC milling