抄録
This study was aimed at developing a new prehole shearing process to promote excellent formability of the subsequent hole- expansion process for manufacturing automobile wheel disks made of high-tensile-stress steel. A “simplified opposed-dies shearing process” was newly proposed for forming a prehole for the hole-expansion process, since the original opposed-dies shearing process requires relatively complicated tool sets regardless of its excellent properties for hole expansion. As a result of the series of experiments with the simplified opposed-dies shearing process as the prehole forming process for the hole expansion process, the simplified opposed-dies shearing process was found to show an improvement of 0.3 in the expansion ratio over that in the case of the conventional shearing process.
