薄板材料のプレス成形における成形限界の予測と加工硬化特性の影響

抄録

The necking limit diagram NLD and the forming limit diagram FLD under the wide-range bi-axial tensile stress conditions were obtained by using various sheet metals of steels, Al-alloys and a copper. The good correlation between the limited strain values of NLD and FLD and the mechanical properties of total elongation and r-value etc. were obtained. Moreover, the strain dependency of the work hardening coefficient n-value in higher strain area was different according to each material. The complex value of n-value and r-value was defined as the equivalent work hardening coefficient n_eq-value in higher strain area. And when the n_eq-value was substituted to Gotoh's modeling of localized necking limited strain, FLD that accuracy is high was able to be predicted.