Development of Shape Fixing Press Forming Technology for High Strength Steel Sheet

New press forming method was developed for ensuring shape-accuracy of draw parts with high strength steel sheet(HSS) of very high tensile strength such as 780MPa. In the new method, step drawing method was combined with crash forming method by applying cam flange die structure to drawing dies. Furthermore, the die structure in the method is simple. At the trial press-forming by the model die even with 780MPa high strength steel sheets, the side wall warps in particular were restrained within a specified tolerance, that is ±0.00067[1/mm] of the variation of curvature(Δ 1/ ρ). Now the method is applied to press-forming some automotive body parts, such as front side member, etc.