NURBS Tool Path Generation Using Dominant Cutter Location Points for Triangular Mesh Surface Machining

To improve efficiency and accuracy of NC machining,an algorithm for NURBS tool path generation using dominant cutter location(CL) points is put forward.CL points of line tool paths are first obtained by intersecting the offset surface of triangular mesh model with a series of sections.Curvature radii in the direction of the line tool paths and that perpendicular to the line tool paths are estimated by vertexs' curvatures of the offset surface.The tool path intervals are determined by cusp height and the curvature radii.Then,an improved algorithm for NURBS curve fitting based on the dominant CL points is proposed.The initial dominant CL points are selected by the method of threshold partition.New dominant CL points are determined by the rule of maximal angle of adjacent lines segments,and the parameters of the dominant points are adjusted by the parameters of the projected points,which correspond to the CL points.Finally,the CL points are fitted into NURBS curves,and NURBS transition is performed between adjacent tool paths so that the file size of NC program is reduced and tool path smoothness is improved.Experimental result indicates that the NURBS tool paths generated by the proposed algorithm have fewer control points,higher fitting accuracy and better smoothness.