Path Generation for CNC Incremental Secondary Extrusion Forming Based on Scallop Height

In order to improve the contour dimension accuracy and surface quality of the formed parts in CNC incremental forming, a method for generating the secondary extrusion forming path was proposed, which can be applied to correct the dimension errors and eliminate the scallop height. First of all, the first extrusion forming path was generated by cutting the cutter location surface according to a certain layer distance, which was obtained by the equidistant offset of the inner surface of the sheet metal part to be formed with a distance of the extrusion forming tool head radius. Then the cutter location points were determined by recognizing the peaks of the scallop height. Finally the secondary extrusion forming path was generated by cutting the cutter location surface according to the height of the average value of the Z coordinate of the cutter location points on the same layer. The digital simulation and experimental results show that the method can improve the contour dimension accuracy and reduce the surface roughness effectively.