스프링백 저감을 위한 초기블랭크 설계

In this study, the methodology to design initial blanks considering the reduction of both springback and flange trimming amounts is introduced. First, the dimensional forming analysis of a trial blank is carried out tsing FEM program and the tentative initial blank shape is determined by cutting the outer edge of the trial blank whose shape is nearly matched with the trimming line. During the shaping the blank edge, the movement of blank outer line is described with a random variables to reduce the sensitivity of initial blank geometry. Next, after performing 2-D FEM forming and springback simulations for the selected sections and optimizing the trimming and springback amounts in terms of section length of the blank, the initial blank is determined. The springback of the initial blank determined by following the proposed method in a stepped s-rail die is tremendously reduced.