Development of shape-fixing, press-forming technology for high-strength steel sheet

摘要

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 780 MPa. 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 780 MPa 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 (Δ1/ρ). Now the method is applied to press-forming some automotive body parts, such as front side member, etc.