公开(公告)号：US20210229153A1

公开(公告)日：2021-07-29

申请号：US17054031

申请日：2019-08-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Koichi KURODA ,  Shuji OTAO

IPC: B21D3/10

Abstract: Method for bend straightening in which a steel pipe having a bend is placed in a state where the steel pipe is convex upward, the steel pipe is pressed from above by a press unit at a target load value, whereby the steel pipe is straightened, the method including: (a) measuring a bottom-dead-center load value Pk when the press unit is at a bottom dead center in the pressing; (b) measuring an amount of change 46 in amount of bend between an amount of bend of the steel pipe before the pressing in step (a) and an amount of bend of the steel pipe after the pressing in the step (a); (c) repeating step (a) and step (b) a plurality of times to create a relational expression Pk=(Δδ); and (d) determining a target load value for next pressing from the relational expression Pk =(Δδ).