A STUDY ON NC-CUTTER PATH GENERATION FOR SUBDIVISION SURFACES

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In this study we proposed methodologies and algorithms of slice-cut and finish-cut tool path generation through which a 3-axis NC cutter path can be generated for subdivision surface model automatically. At the beginning, suitable subdivision scheme in order to satisfy industrial requirements, and then a process planning is determined. Next we employ a Z-map model that grid interval of x/y direction can be decided by cutting tolerance and tool parameter to set up mesh points from limit subdivision surface in order to reduce the use of computer memory and raise the computing speed. For work pieces we present a slice-cut tool path generation method with flat-end mills, we generate a cover mesh and set up a Z-map model for it, calculated their cutter contact points and cutter location points and adjust the cutter height to achieve tool paths for every slice. For finish-cut tool path generation we use ball-end mill, and achieve the path by calculating the cutter contact paths with projection points between the limit surface and the Z-map model, and then offset them to cutter location paths. Finally we implement the method and present some examples. For these two kinds of paths, we calculated curvature radius of the limit surface in order to avoid gouging. All of these cutter paths are computed automatically if there is no problem in parameter setting for the desired NC path plan, and the implementation shows that these paths are generated rapidly.