Method for manufacturing hot-rolled steel sheet, steel sheet cutting location setting device, steel sheet cutting location setting method, and steel sheet manufacturing method

Patent metadata

Field	Value
Publication number	US-10730088-B2
Application number	US-201515314744-A
Country	US
Kind code	B2
Filing date	May 13, 2015
Priority date	May 30, 2014
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

A method for manufacturing a hot-rolled steel sheet having a large thickness and a large width, a larger sheet width and a lower temperature can stably be cut at a cutting load equal to that of a conventional steel sheet having a usual sheet thickness, a usual sheet width and a usual temperature. In a rough rolling step, the steel sheet is formed so that the shortest length L (mm) from a concave portion bottom to a convex portion top of the fishtail shape satisfies Equation (1) mentioned below, and an intermediate portion between the concave portion bottom and the convex portion top, defined as a desired cutting location, is cut:

(2 X +30)≤ L ≤300  (1),

in which X is a maximum deviation (mm) of the cutting location of a crop cutting machine and 0≤X≤90.

First claim

The invention claimed is:

1. A method for manufacturing a hot-rolled steel sheet which comprises a rough rolling step and a finish rolling step and in which after the rough rolling step and before the finish rolling step, a crop portion of a front end of a steel sheet in a conveying direction is cut with a crop cutting machine, and then the steel sheet is finish-rolled in the finish rolling step to manufacture the hot-rolled steel sheet,
wherein in the rough rolling step, a shape of the crop portion formed at the front end of the steel sheet in the conveying direction is adjusted into a fishtail shape, in which both ends of the steel sheet in a width direction project in the conveying direction with respect to a central portion of the steel sheet in the width direction, by width rolling of a width rolling machine and horizontal rolling of a horizontal rough rolling machine, the steel sheet is formed so that the shortest length L (mm) from a concave portion bottom to a convex portion top of the fishtail shape satisfies Equation (1) mentioned below, and an intermediate portion between the concave portion bottom and the convex portion top, defined as a desired cutting location, is cut:
(2 X+ 30)≤ L≤ 300  (1),

in which X is a maximum deviation (mm) of the cutting location of the crop cutting machine and 0≤X≤90.

2. The method for manufacturing the hot-rolled steel sheet according claim 1 ,
wherein in the rough rolling step, in addition to the crop portion formed at the front end of the steel sheet in the conveying direction, a shape of a crop portion formed at a rear end of the steel sheet in the conveying direction is adjusted into a fishtail shape that satisfies Equation (1) mentioned above, and an intermediate portion between a concave portion bottom and a convex portion top of the fishtail shape, defined as a desired cutting location, is cut.

3. The method for manufacturing the hot-rolled steel sheet according to claim 1 ,
wherein the desired cutting location is set to a portion between a location of (X+20) mm from the concave portion bottom toward the convex portion top of the fishtail shape and a location of (X+5) mm from the convex portion top toward the concave portion bottom.

4. The method for manufacturing the hot-rolled steel sheet according to claim 1 ,
wherein in the rough rolling step, a width rolling amount W R (mm) by the width rolling machine is from 30 to 50 mm.

5. The method for manufacturing the hot-rolled steel sheet according to claim 1 ,
wherein in the rough rolling step, the steel sheet is subjected to width reduction by a sizing press prior to the width rolling by the width rolling machine.

6. The method for manufacturing the hot-rolled steel sheet according to claim 5 ,
wherein in the rough rolling step, a width pressing amount W P (mm) of the sizing press is from 150 to 250 mm and a width rolling amount W R (mm) by the width rolling machine is 10 mm or more and smaller than 40 mm.

7. The method for manufacturing the hot-rolled steel sheet according to claim 5 ,
wherein in the rough rolling step, a width pressing amount W P (mm) of the sizing press is smaller than 150 mm or in excess of 250 mm and 400 mm or less and a width rolling amount W R (mm) by the width rolling machine is from 30 to 50 mm.

Assignees

• Jfe Steel Corp

Inventors

• Goto Hiroto
• Nakata Naoki
• Kimura Yukio
• Miyake Masaru
• Ueoka Satoshi
• Nishiura Nobuo
• Shirasaki Sonomi
• Kato Takaomi

Classifications

• B21B1/22 Primary

  for rolling {plates, strips,} bands or sheets of indefinite length (B21B1/42 takes precedence) · CPC title

• B21B1/224

  Edge rolling of flat products · CPC title

• B21B38/006

  for measuring temperature · CPC title

• B21B2263/20

  End shape; fish tail; tongue · CPC title

• B21B2001/225

  by hot-rolling · CPC title