公开(公告)号：US20220241838A1

公开(公告)日：2022-08-04

申请号：US17626321

申请日：2020-07-10

Applicant: NIPPON STEEL CORPORATION

Inventor： Jun NITTA ,  Takashi YASUTOMI ,  Ryo TABATA

IPC: B21D28/34 ,  B21D28/14 ,  B23D15/08

Abstract: The present invention has as its technical problem to provide a punching method able to stably secure a stretch-flangeability equal to or greater than the case of using a punch having a flat blade at its bottom surface. The punching method of the present invention is a method of punching a metal sheet using a punching and shearing device provided with a punch having an upper blade having a horizontal part with respect to the cutting line in part and having parts other than the horizontal part comprised of inclined parts and a die having a lower blade wherein the upper blade used for the punching process has a shape where the inclined parts first contact the metal sheet at the time of a punching process.