The Technical Research Of The Effect Of Drawbead On The Drawing Forming And Springback

The forming defects appear in the car cover process of forming,such as wrinkling,cracking,springback and other phenomena.Engineers often set by drawbead to improve the sheet forming quality.The traditional drawbead is simplification and leads to the terrible blank forming quality.In this paper,based on the theory of sheet metal plastic forming,designing of five different combinations of drawbead,the material of HSLA350 and AL6061 is analyzed by finite element numerical simulation method.The forming limit graph and the thinning rate of the six models were obtained respectively.The results show that the the drawbead apart from 40 mm can change the stress distribution of sheet metal and improve the quality of sheet metal forming.In the six models,the principal stress of the sheet in the drawbead apart from 40 mm model is the smallest as well as thinning rate.In the springback numerical simulation,the springback and sidewall angle of all U-shaped models are predicted.The results show that the drawbead can effectively restrain the springback of the side wall,and the sheet springback of the drawbead apart from 40 mm model is the smallest.It reveals the relationship between the angle of the U-shaped side wall and the stress gradient of the sheet.The drawbead apart from 40 mm can change the stress gradient and its gradient value is the smallest.It is proved that the hardened material in drawbead apart from 40 mm does not flow into the cavity again,so as to improve the warping of U-shaped side wall.This paper designs the U-shaped stamping experiment mold,and completes the stamping experiment of six models for two materials.The experimental results show that the sheet forming quality in the drawbead apart from 40 mm model is the best,without wrinkling or cracking.In the results of thinning of the sidewall,the thinning rate of drawbead apart from 40 mm model of HSLA350 is the smallest,and the thinning rate of all models of AL6061 is close.In the results of the warping of the sidewalls,the angle of the drawbead apart from 40 mm model in the two materials is smaller than that of the other groups,and the accuracy of the simulation results are verified.