角筒成形における部分熱処理材の軟化領域の最適化

抄録

To improve the press formability of aluminum alloy sheets, method using partially softened blanks, such as tailored heat-treated blanks method, have been investigated, in which aluminum alloy sheets whose strength has been distributed are formed. In square-cup forming, it is known that the softening corner flanges improves drawability, but it was not clear which region of the blank should be softened to improve drawability. In this study, the optimal region to be softened for the deep drawing of a square cup was investigated by experimental and numerical analyses. The A6061-T6 sheets were locally solution-treated and softened. Then, square-cup drawing tests were performed. Six types of softened region were prepared to investigate the effects of the distance from the center to the boundary of the softened region at the corner and of the softened region ratio in straight sections. In the blank with the widest softened region in straight sections, the shrinkage deformation of the corner flange was suppressed. Therefore, there was an appropriate range for the softened region ratios of straight sections and corners. The formability of blanks with appropriate softened regions was improved by 1.2 times compared with that of T6 sheets. In addition, a similar optimal value was obtained by optimization by numerical analysis.