Research On Tool Path Generation Technology For Triangular Mesh Surface CNC Machining

Complex geometric parts with free form surfaces are widely used in aerospace,automotive and die-mold industries. The CNC machining of these sculptured parts isof one of the key technologies during production. Triangular mesh surface isbecoming popular in CAD/CAM and CAE systems owing to its simple data structureand topological flexibility. The research of tool-path planning on triangular meshsurface is important for scattered data points NC machining and realizing theintegration of CAE and CAM，which can shorten the manufacturing cycle.Tool-path planning method on triangular mesh surface is studied in this paper. Inorder to get constant scallop-height tool path，a three-dimensional scallop-heightmodel is set up by using the tool envelope，and constant scallop-height tool path isobtained. Some details investigated in this paper are stated as follows.(1) The quick positioning of an arbitrary point on the triangular mesh and itslocal coordinate representation is discussed. The computing method of normal vectorand curvature of the cutter contact point are discussed based on the proposedpositioning method.(2) The envelope surface of the tool is calculated directly from CL-data. And athree-dimensional scallop-height model is set up based on the envelope surface andcutting theory, the scallop-height between two neighboring paths is calculated basedon the proposed scallop-height model. A constant scallop-height tool path withoutinterference planning algorithm based on triangular mesh surface is proposed.(3) The machining precision and efficiency of the proposed algorithm is analyzedand tested with different triangular mesh surfaces. Comparative results between othercommon tool path planning methods indicate that the presented algorithm is of higheraccuracy, it can obtain constant scallop-height and shorter tool path withoutinterference.