Study Of The Effect Of Punch Speed On Sheet Metal Forming

Deep drawing is an important method for sheet metal forming. The benefit of drawing, such as quality, cost and efficiency can not be comparable replaced by other processes. Traditional forming process often deeply depends on the accumulation of experiences of practitioners, during which various process parameters need to be modified repeatedly. With the development of computer technology and CAE method, the finite element method has been widely used for sheet metal drawing forming process simulation.In the present study, the dynamic explicit algorithm was utilized as the FEM solving method. The Johnson-Cook constitutive equation including strain rate effect was used for simulating the cylindrical cup drawing under different punch speeds. The round sheet model was meshed into different regions with the S4R element. The contact friction was based on surface-to-surface contact of penalty function method. The damage and failure criteria was established by the forming limit curve (FLC) deduced by analytical method.The effects of constant and variable punching methods on forming were investigated with different punch speeds. The von-Mises strain and stress fields and variety of section thickness were studied. Finally, the forming limit diagram was analyzed.Based on the damage and evolution criteria of FLD, the golden section method was carried out to simulate the limit drawing rate and the effect of drawing methods and speed on the rate.The simulation results show that in a certain range of punch speed, with the increased speed, the differences of the effects on the sheet deep drawing under variable speed and constant speed decrease. The limit drawing ratio can be obtained by simulation and there is no obvious difference from two speed mode, the limit drawing ratio decreases with the increased punch speed.