Research On Tool Path Planning And NC Program Generation Of Freeform Surface

Freeform surface, also called sculptured surfaces, have been widely used in variousengineering applications. Freeform surfaces are usually designed to meet or improve anaesthetic and functional requirementsuch as turbine blades, dental restoration and so on.The efficient machining of freeform surfaces is an important issue in modern industry.With the development of three-dimensional measurement technology and reverse engi-neering, the CNC machining technology of discrete mesh surfaces has been developingrapidly. So the article has conducted in-depth research the CNC machining technologybased on triangular mesh surfaces.In view of the low computational efficiency of traditional cutting plane method, theintersection based on adjacency of mesh surfaces was designed and the redundant cut-ter contact point data was removed. The situations of mesh surface intersecting withcutting plane were analyzed. Fully considering the adjacency relationship,the adjacentintersection point was found., concurrently,the sort work of which was done. On thisbasis, the contour parallel tool path generation algorithm,which took the vertex-basedoffset method,constructed local intersection plane and done clipping operation by theintersection-point-based judgment method of contour loop direction,was designed, gen-erated the constant cusp contour parallel tool path and reduced the length of tool path.For tool positioning of five axis NC machining,the paper studies the algorithm foroptimized tool axis vector overall in a configuration space(C-space) of fillet tool orienta-tion angle without interference. Cutter contact points are calculated by section method.Accordingtolocalinterference,rearinterferenceandglobalinterferenceofthetool,thetoolC-space was calculated. In the C-space,allowing for the kinematics performance of themachine tool,the algorithm took the directed graph of the shortest path Dijkstra algorithmwith the adjacent cutter contact angle of the two variation of velocity as a weight,achievedthe tool axis vector overall optimization. Two angular velocity and acceleration variationof the tool was more uniform.The standard APT file format was analyzed,tool-path file using the APT file as tool-path information carrier were output and the post processing algorithm for five axis CNCsystem DMU50V with a tilt table was used to generate NC code. According to the CNCmachining process, the framework of NC automatic programming system based on trian- gular mesh model was developed. The paper verified the validity of the function modules,generated the NC program and done VERICUT simulation to verifies the correctness ofprogram.