Development of Hot Stamping for Automotive Panel Parts with Step-Shaped Wall

Abstract

We developed a hot stamping method for panel parts with a step-shaped wall. The die-set for the developed method divides the punch at a step-shaped wall into an outer punch and an inner punch. The outer punch is placed first. In addition, an opening is added to the blank of the developed method. The developed method makes it possible to change the main forming type from draw forming to cylindrical stretch flange forming in the middle of a forming stroke. The stretch flange forming can prevent a fall in temperature at a hole edge, because the hole edge does not come into contact with the die-set during forming and because the high ductility of high-temperature materials can be used, making it advantageous for hot stamping. If the preceding amount of the outer punch is large with the developed method, the effect of suppressing wrinkles is large but the sheet thickness reduction that can cause cracking rises. If the preceding amount of the outer punch is small, the rate of sheet thickness reduction ratio is greatly restrained, but the wrinkles become larger. By setting an appropriate preceding amount of the outer punch with the developed method, forming without cracks or wrinkles is possible.

Best Papers Awarded by JILM and JSTP in <i>Materials Transactions</i>

“…Articles of 10-20 are annually published through JSTP in Materials Transactions: for example, 16 articles in 2021-2022. 4,5,[94][95][96][97][98][99][100][101][102][103][104][105][106][107] The awarded paper of Takahashi et al 1,60) through JILM is concerned with measurements of interdiffusion and impuritydiffusion coefficients in multicomponent Ti alloys, which are fundamental quantities to understand phenomena occurring at elevated temperatures. Indeed, comprehensive study was presented on the Ti-Al-Zr ternary system following their earlier studies on the Ti-Al-X (X = V, Cr, Fe, Co) ternary systems.…”