Sheet Metal Straight-wall Parts' Forming Mechanism And Process Research Based On Digital Incremental Forming

As a digital flexible manufacturing technology, sheet metal numerical control single-point incremental forming was proposed firstly by a Japanese researcher whose name is Shigeo MATSUBARA in the 1990's. Without dies and punches which are necessary in the traditional plastic forming for sheet metal, the new technology is especially suitable for the sheet metal part forming in the course of developing new products such as articles of daily use and covering parts of automobile. At the same time, it is widely believed that applying to the technology can get shortened cycle of product development, reduced cost and less investment risk.However, the taller straight-wall parts can not be produced directly, which is the most difficult problem to be resolved. In this paper, the general process based on digital incremental forming is discussed firstly. Two basic deformation models are used to analyze the whole process of deformation. The sheet metal is subjected to bending and unbending with stretching, which are repeated in the course of forming process. Then, the deformation mechanism of bending and unbending is developed. According to the mechanism, why taller straight-wall parts can not be produced directly is explained clearly. Secondly, the possibility of multi-pass forming is discussed.According to the character of CNC forming, route planning method is most important for straight-wall parts' forming. Two got route planning methods are compared. A new planning method is designed to make metal flow easily. The change of straight-wall's thickness is researched. The changed marks on the part's down surface of three stages, that is, the first pass, one of the passes between the first pass and the last pass, and the last pass are compared. In the last, metal flow rules are summarized. Some process parameters affecting the quality of forming are in return discussed.