曲がりハット材の捩れスプリングバック予測に及ぼす金型・プレス機弾性体モデル化範囲の影響

―金型弾性変形考慮によるスプリングバック予測の高精度化 第1報―

抄録

It is difficult to predict springback, particularly in torsion, with high accuracy by finite-element (FE) simulation. Generally, more accurate springback prediction has been achieved mainly as a result of improved material models such as the Bauschinger effect and plastic anisotropy models. In this study, FE analysis of press forming taking account of tool deformations was carried out in addition to considering an accurate material model in order to improve springback prediction. Die deformations were measured to verify the accuracy of FE analysis. Press forming of curved hat-shaped products was carried out and the effect of the die stroke on torsion springback was examined. The effect of the elastically modeled parts of a press machine on springback prediction was investigated to improve the prediction of the relationship between the die stroke and torsion springback. It was demonstrated that the larger the number of elastically modeled parts, the better the correlation between the experimental results and the numerically simulated results. The differences in the torsion springback predictions between FE simulations with three different combinations of elastic and rigid parts were small although elastically modeled simulations have much better agreement with experimental results than the simulations with the fully rigid tool model.