A Study On Forming Path Generation For Sheet Metal 5-Axis CNC Incremental Forming

The sheet metal incremental forming technique is a kind of recently developed flexible and dieless forming technology, which can directly fabricate the sheet pieces from CAD model date quickly and economically. With the advantage of the short production cycle and the low production cost, the technique is adapted for product trial-manufacture and development, research and small batch, many varieties personalized production requirements, so it has wide application prospects in the fields of aerospace, shipbuilding, automobile and so on. In this paper, the study on forming path generation for sheet metal 5-axis CNC incremental forming has the important practical significance to improve forming quality and accuracy, and popularize the 5-axis CNC sheet incremental forming technique. The main research comments are as follows:First of all, to ensure the reasonable gap value between the press tool head and support, this paper researches the algorithm to generate the surface model of cutter contact points base on the non-equidistant offset algorithm of STL model. That is to find out the direction of the best offset vector that was microscale modified by offset vector which was estimated by mass vertexes on STL model, and joint the vertexes along the direction of its offset vectors to regenerate the surface of cutter contact points. At the same time, in order to create noninterference calculation surface of cutter location points and improve its precision, this paper also puts forward a equidistant offset algorithm base on vertexes offset of subdivision surface. Secondly, the paper presents a minimum spiral path interval generation method base on scallop height. The minimum path intervals in the spiral path rising direction and the rotation direction are calculated base on scallop height and the radius of press tool, and then, on the basic of the nonuniform cutting in the spiral path rising direction and the inequality angle revolving cutting in the rotation direction, according to the amont of revolving cutting, every two adjacent horizontal cutting layers were subdivided and cut, and finally, link two adjacent intersections which was intersected between the line of subdivision cutting and line of inequality angle cutting to create the spiral path. Thirdly, by using the finite element analysis softwave of ANSYS/LS-DYNA, the effect of pressing directions on forming precision in the 5 axis CNC incremental forming was studied, which is provided a theoretical bases for confirming the pressing directions of 5 axis CNC incremental forming. At last, this paper provides a method to calculate the tilt angle of pressing tool for 5 axis CNC incremental forming, and the process of pressing tool motion in 5 axis CNC incremental forming was simulated by this paper.