Efficient numerical-control simulation for multi-axis machining based on three-level grids
摘要
This paper presents an accurate and efficient method for computing machined part geometry and determining cutter-workpiece engagement (CWE) in multi-axis milling. The proposed method is based on volumetric models, with three types of three-level data structures proposed to represent a solid workpiece voxel model for a sparse and memory-efficient implementation. At each cutter location, every coarse workpiece voxel is efficiently updated from the top to the lower level, and the vertex states and edge intersection points inside each bottom-level voxel crossed by the cutter envelope surface continue to be updated using the dynamic marching cube algorithm. Meanwhile, the finest intersecting voxels are projected onto the cutter surface such that the projected engagement patches connect to form the required engagement map. Finally, according to the lookup table, a triangular mesh of the machined part is built by reconstructing and fusing the approximation polygons inside the bottom-level workpiece surface voxels. Quantitative comparisons of the proposed method against the two-level grid and the tri-dexel model demonstrated the high accuracy and considerable ability of the proposed method to provide more significant and stable efficiency improvement without being affected by a large branching factor owing to its more efficient spatial partitioning.