Parallel processing for 2-1/2D machining simulation

Abstract

Continued progress in the area of solid modeler based machining process simulation is hindered by the complexity growth that occurs for a large number of tool paths n. For this reason, many researchers have adopted the Z-buffer approach. Boundary-representation (B-rep), however, remains the dominant choice for commercial modelers. This paper begins by reviewing the current state of solid modeler based machining simulation. Using an industrial example, the growth rate, for a simple feed rate scheduling application, is estimated to be O(n1.5). It is shown that round robin parallel scheduling quickly becomes inefficient due to the fraction of time spent on tool swept volume Boolean subtractions. The tool path sequence is next heuristically subdivided into nearly equal size neighbor groups. Only the Boolean subtractions required for accurate simulation are included in the group. Each group is then simulated in parallel, achieving a greatly reduced wall clock running time. Computational geometry methods are described that permit rapid identification of tool path neighbors. It is shown that, under practical assumptions, the total number of tool path neighbor pairs is O(n), justifying the benefit of parallel processing. Both dual CPU and networked parallel solutions are implemented. Geometric images and running time plots are included to illustrate. Discussion is included, with proposed steps to further reduce calculation time.