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).

公开(公告)号：US20230054014A1

公开(公告)日：2023-02-23

申请号：US17758049

申请日：2020-09-28

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazuhiro SHIMODA ,  Kouji YAMANE ,  Koichi KURODA ,  Yuji INOUE ,  Shusuke SHIMOOKA ,  Kazuyuki MURAKAMI ,  Kota SHINDO

IPC: B21B19/04 ,  B21B27/02

Abstract: A method disclosed herewith is a method for producing a first seamless metal tube with a first wall thickness and a second seamless metal tube with a second wall thickness by using a three-roll-type inclined rolling mill, and the method includes a first inclination rolling step (#5), a setting changing step (#10), and a second inclination rolling step (#15). At the first inclination rolling step, a first workpiece is rolled by the inclined rolling mill. At the setting changing step, a setup condition of the inclined rolling mill is changed in a manner (a) or (b) as described below. At the second inclined rolling step, a second workpiece is rolled by the inclined rolling mill under the changed condition. (a) When the second wall thickness is smaller than the first wall thickness, the cross angle of each of the inclined rolls is made greater than the cross angle set for the first inclination rolling step. (b) When the second wall thickness is larger than the first wall thickness, the cross angle of each of the inclined rolls is made smaller than the cross angle set for the first inclination rolling step.