Research On Springback Control Of Sheet Metal Stamping Using Die Face Compensation

Springback is a common phenomenon in sheet metal forming, caused by the elastic redistribution of the internal stresses during unloading. It has been recognized that springback is essential for the design of tools used in sheet metal forming operations because it affects the dimensional accuracy. Traditionally, process design and die optimization based on trial and error method is a long cycle and high cost process, which restricts the development of mould industry. If accurate springback prediction is available for compensating shape deviation before designing die, it may reduce the expensive time consuming.At present, the numerical simulation as a modern technology is more and more employed. However, springback is the last stamping step, the accurateness of predicting springback is not only subject to the forming simulation, but also related to springback simulation. Therefore, how to improve its computational accurateness and to research die compensation strategy based on springback numerical simulation are one of the difficulties in sheet metal forming and become the main task of this paper.The followings are the main content done in this paper:1) The theories of springback, the factors affecting the springback and the measures decreasing springback are demonstrated. The key technologies of springback are analyzed. The algorithm of die face compensation is studied.2) Taking example for U benchmark at the NUMISHEET'93 Conference. Firstly springback is predicted effectively and controlled using process method on the basis of optimized numerical simulation, then springback control measure of U shape part using die compensation by PAM-STAMP 2G is studied. The numerical simulation method of die face compensation is set up. The results of springback control and existing questions are demonstrated. Finally the way to redesign compensated die CAD is discussed by the optimized design mean PANELSHOP and the integrative measure of die face CAD design, CAE springback compensation and compensated die redesign.3) On the basis of the method of U shape part, the complicated screw vane in stamping industry is investigated. Firstly the finite element model is set up and the optimization method is analyzed. Then springback is studied and predicted effectively using numerical simulation and bending test. Finally the control effect of the shape erro is analyzed. To sum up, the springback problem of the intricate part is virtually solved through die compensation.