Tool-Path Generation And NC Machining Simulation Of Recursive Subdivision Surface Model

As a highly efficient and succinct scheme, the subdivision surface has been widely used in the field of computer graphics and 3D surface modeling. To extend its application in industry, the tool path generation algorithm and simulation for 3-axis NC machining of the subdivision surface model is studied. Two interference-free tool-path generation algorithm using ball-end mills in 3-axis machining are developed.This thesis presents methods to generate tool-path for the rough machining and finish machining of subdivision surfaces. Firstly, tool-path for rough machining is generated through setting cutting depth, machining allowance and other parameters. Interferences are resolved through raising the z-components of the generated CL point according different kind of situations. And then two methods to generate tool-path for finish machining is presented. The first one is based on the offset surface of subdivision model. Through mapping the original mesh node by node, the offset surface is generated. It can get the interference free tool-path directly from the offset surface without complex interference check and process. But this method can't be used to generate tool-path for the kind of surfaces whose curvature varies sharply, since singularity may appear when creating the offset surface. It is computation expensive to resolve the singularity. In order to generate tool-path quickly, another method is presented. It can generate interference free tool-path directly from the section line of the triangulated surface model. Search each vertex of the model to get the triangles which may be interfered using the radius of the cutter. Get the interference-free CL point through offsetting the original CL point.In order to ensure the correctness of the tool-path, a NC machining simulation method is presented, and error analysis is given to the cutting result to make sure the tool-path can obtain the given precision. At last convert the cutter location data into NC code which can be used on the Siemens 802D NC system through post processing.