部材端部のフランジアップ成形性に及ぼす稜線曲率半径および引張特性の影響

抄録

The numerical analyses and experiments of press-forming were carried out in order to clarify the mutual effects of the punch shoulder radius R_p, flange height H and mechanical properties on flange-up formability for the flange in the longitudinal edge. The results showed that the formability is strongly mutually affected by not only R_p and H but also the r value and plastic tangent modulus normalized by yield stress H’/YP. When R_p is small and H is high, the r value and H’/YP also significantly affect the formability. As a result, the formability of high-tensile-strength steels, whose r value and H’/YP are relatively small, is inferior to that of mild steel. Moreover, it was clarified that when R_p is small and H is high, the bending radius of sheets around the base of the flange becomes smaller than R_p during forming, which causes strain concentration in the flange edge. Therefore, it is suggested that the bending radius of sheets during forming should be controlled to be larger than R_p to obtain good formability.