NC Tool-Path Generation And Milling Simulation For Triangular Bézier Surface

To improve efficiency of the tool path generation for triangular Bezier surface and solve the issues of tool-path interference, poor adaptability to tool and single form of tool-path as well as other issues that tool-path doesn't meet the actual machining demand, algorithms for generating tool-path based on triangular Bezier surface and numerical control milling simulation are proposed. The intersection of triangular Bezier surface and the NC tool-path generation based on triangular Bezier surface were studied in this paper. An algorithm of rapidly getting intersection curves for triangular Bezier surface is proposed. Based on triangular Bezier surface model, the method for obtaining the interference-free cut location points for flat end tool and ball end tool was researched. With an eye on different driving-model, the method for finishing toolpath generation and that of roughing tool-path and the algorithms for numerical control milling simulation are also given. The main achievements and innovations are as follows(1) The dynamic spatial indexing structure named R*S tree was introduced to orgnize topological structure of triangular Bezier surface models. so that the triangular Bezier patches are located quickly and exactly, the efficient method for triangular Bezier surface intersection was studied, thus the efficiency of NC tool path generation are improved:(2) An in-depth analysis of the geometric feature of triangular Bezier surface was made. based on triangular Bezier surface, the interference-free cut location points for flat head tool and ball head tool were obtained, the drive-points of cut location were planed according to the particular shape of the workpiece, At last, different forms of finishing NC tool path like direction-parallel finishing NC tool path, circle finishing NC tool path as well as helix and cylinder finishing NC tool path were generated.;(3) The principle of NC tool-path generation and the form of NC tool-path were analized, the roughing tool-path for direction-parallel and contour-parallel were achieved. then the tool-path post-processing mechanism which were developed by our laboratory was used to generate the NC code to meet the three-axis CNC machining centers VB-825A and the multi-axis CNC machining centers DMU70ev;(4) NC milling simulation based on the the discrete triangular mesh model for Bezier surface models was studied, the R*S tree index for upper-surface nodes of mesh model was constructed, based on which the nodes within cutting region can be obtained quickly. The tool path segments within cutting projection region of node were computed. the minimum adjustment height of node within cutting projection region was calculated and then the z-value of node was changed. Thus, the real-time dynamic display of NC milling simulation was realized.