公开(公告)号：US20210220897A1

公开(公告)日：2021-07-22

申请号：US16755504

申请日：2017-12-25

Applicant: NIPPON STEEL CORPORATION

Inventor： Yasunori SAWA ,  Masahiro SAITO ,  Shigeru YONEMURA ,  Akira EGAMI ,  Kohki NAKAMURA

IPC: B21D28/26 ,  B21D53/88

Abstract: In a method for producing an outer panel having a character line, a punch includes a projecting portion for forming a bent surface of the character line at a punch top portion, and a punch shoulder R portion. A contact pressure applied to a blank by at least one of the projecting portion and the punch shoulder R portion is higher than a contact pressure applied to the blank by a remaining portion of the punch which excludes the projecting portion and the punch shoulder R portion. A static friction coefficient of a first portion of the punch which includes at least one of the projecting portion and the punch shoulder R portion with respect to the blank is larger than a static friction coefficient of a second portion of the punch which excludes the first portion with respect to the blank.