US-12623264-B2 - Manufacturing method and manufacturing equipment of cold-rolled steel sheet

Abstract

A manufacturing method of a cold-rolled steel sheet in which the method uses a full-width heating device that heats a steel sheet over an entire area in a width direction of the steel sheet, an edge heating device that heats end portions in the width direction of the steel sheet, and a cold rolling mill that rolls the steel sheet and that is arranged on a downstream side in a rolling direction with respect to the full-width heating device and the edge heating device, the method includes: heating the steel sheet by using the full-width heating device and the edge heating device in such a manner that temperatures of the end portions in the width direction becomes higher than a temperature of a central portion in the width direction of the steel sheet on an entry side of the cold rolling mill.

Inventors

• Daiki HIOKA
• Yukihiro Matsubara
• NORIKI FUJITA
• Masaki Hino
• Tetsuya Arakawa
• Miwa OHASHI

Assignees

• JFE STEEL CORPORATION

Dates

Publication Date

20260512

Application Date

20211215

Priority Date

20210430

Claims (8)

1. 1 . A manufacturing method of a cold-rolled steel sheet in which the method uses a full-width heating device that heats a steel sheet over an entire area in a width direction of the steel sheet, an edge heating device that heats end portions in the width direction of the steel sheet, and a cold rolling mill that rolls the steel sheet and that is arranged on a downstream side in a rolling direction with respect to the full-width heating device and the edge heating device, the method comprising: heating the steel sheet by using the full-width heating device and the edge heating device in such a manner that temperatures of the end portions in the width direction becomes higher than a temperature of a central portion in the width direction of the steel sheet on an entry side of the cold rolling mill, wherein the temperatures of the central portion in the width direction and the end portions in the width direction of the steel sheet on the entry side of the cold rolling mill are calculated from following expressions (1) and (2), the temperatures calculated from the expressions (1) and (2) being configured to change depending on an Si content α: T C ≥0.1α 4.5 +15 (1) T E ≥0.1α 4.8 +15 (2) T C : Steel sheet temperature of a central portion in a width direction of a steel sheet on entry side of a rolling mill [° C.] T C ≤200° C. T E : Steel sheet temperatures of end portions in a width direction of a steel sheet on entry side of a rolling mill [° C.] T E ≤200° C. α:Si content [%] 0<α≤4.5.
2. 2 . The manufacturing method of the cold-rolled steel sheet according to claim 1 , wherein heating the steel sheet over the entire area in the width direction of the steel sheet by the full-width heating device, heating the end portions in the width direction of the steel sheet by the edge heating device, and rolling the steel sheet by the cold rolling mill are performed in this order.
3. 3 . The manufacturing method of the cold-rolled steel sheet according to claim 1 , wherein heating the end portions in the width direction of the steel sheet by the edge heating device, heating the steel sheet over the entire area in the width direction of the steel sheet by the full-width heating device, and rolling the steel sheet by the cold rolling mill are performed in this order.
4. 4 . Manufacturing equipment of a cold-rolled steel sheet, the equipment comprising: a full-width heating device that heats a steel sheet over an entire area in a width direction of the steel sheet; an edge heating device that heats end portions in the width direction of the steel sheet; and a cold rolling mill that rolls the steel sheet and that is arranged on a downstream side in a rolling direction with respect to the full-width heating device and the edge heating device, wherein the full-width heating device and the edge heating device heat the steel sheet in such a manner that temperatures of the end portions in the width direction becomes higher than a temperature of a central portion in the width direction of the steel sheet on an entry side of the cold rolling mill, wherein the full-width heating device and the edge heating device heat the temperatures of the central portion in the width direction and the end portions in the width direction of the steel sheet on the entry side of the cold rolling mill to temperatures that are calculated from following expressions (1) and (2), the temperatures calculated from the expressions (1) and (2) being configured to change depending on an Si content α: T C ≥0.1α 4.5 +15 (1) T E ≥0.1α 4.8 +15 (2) T C : Steel sheet temperature of a central portion in a width direction of a steel sheet on entry side of a rolling mill [° C.] T C ≤200° C. T E : Steel sheet temperatures of end portions in a width direction of a steel sheet on entry side of a rolling mill [° C.] T E ≤200° C. α:Si content [%] 0<α≤4.5.
5. 5 . The manufacturing equipment of the cold-rolled steel sheet according to claim 4 , wherein the full-width heating device and the edge heating device are installed at positions within 10 m from the entry side of the cold rolling mill.
6. 6 . The manufacturing equipment of the cold-rolled steel sheet according to claim 4 , wherein the full-width heating device is a solenoid-type induction heating device.
7. 7 . The manufacturing equipment of the cold-rolled steel sheet according to claim 4 , wherein the full-width heating device and the edge heating device are arranged in this order from an upstream side in the rolling direction of the cold rolling mill.
8. 8 . The manufacturing equipment of the cold-rolled steel sheet according to claim 4 , wherein the edge heating device and the full-width heating device are arranged in this order from an upstream side in the rolling direction of the cold rolling mill.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This is the U.S. National Phase application of PCT/JP2021/046317, filed Dec. 15, 2021, which claims priority to Japanese Patent Application No. 2021-077586, filed Apr. 30, 2021, the disclosures of these applications being incorporated herein by reference in their entireties for all purposes. FIELD OF THE INVENTION The present invention relates to a manufacturing method and manufacturing equipment of a cold-rolled steel sheet. BACKGROUND OF THE INVENTION Conventionally, a single-stand reverse mill such as a Sendzimir mill, or a tandem mill having a plurality of stands is used in cold rolling. In any case, a steel sheet temperature on an entry side of a rolling mill in a first path is often a room temperature. Incidentally, in cold rolling of a silicon steel sheet (electrical steel sheet) having a high Si content, brittle fracture of the steel sheet is likely to be generated in a case where a steel sheet temperature is low. As a fracture form at this time, there are a case where the steel sheet is fractured from end portions in a width direction, a case where the steel sheet is fractured from a central portion in the width direction, and the like. In any case, as a measure against the fracture, it is effective to increase the steel sheet temperature during the cold rolling. From such a background, a method of controlling the fracture of the silicon steel sheet by heating the silicon steel sheet before the cold rolling has been proposed. For example, Patent Literature 1 discloses a method of heating end portions in a width direction of a steel sheet in such a manner that a target temperature designated on an entry side of a rolling mill is reached. Furthermore, Patent Literature 2 discloses a method of uniformly heating and rolling an entire area of a steel sheet. PATENT LITERATURE Patent Literature 1: Japanese Patent Application Laid-open No. 2012-148310Patent Literature 2: Japanese Patent Application Laid-open No. 2011-79025 SUMMARY OF THE INVENTION As described above, a technology of controlling generation of brittle fracture when a silicon steel sheet having a high Si content is cold-rolled has been proposed. However, in a technology of heating only end portions in a width direction of a steel sheet, there is a possibility that brittle fracture at a central portion in the width direction is generated since a steel sheet temperature near the central portion in the width direction is low. In addition, in a technology of uniformly heating an entire area in a width direction of a steel sheet, there is a possibility that the entire steel sheet is heated by application of more energy than necessary, and it is considered that there is room for reviewing from a viewpoint of SDGs (sustainable development goals). Aspects of the present invention have been made in view of the above problems, and an object thereof is to provide a manufacturing method and manufacturing equipment of a cold-rolled steel sheet, which are capable of stably rolling a silicon steel sheet with a low environmental load. In order to achieve the above object, the inventors of the present invention have intensively conducted studies, and found that a fracture control temperature (steel sheet temperature having a high fracture control effect) is higher at end portions in a width direction than at a central portion in the width direction. Thus, the inventors have conceived that it is very effective to combine a full-width heating device that heats an entire area in a width direction of a steel sheet and an edge heating device that heats end portions in the width direction of the steel sheet and to appropriately control and use output of the both in terms of fracture control and environment, and have arrived at the following invention. A manufacturing method of a cold-rolled steel sheet according to aspects of the present invention is the method that uses a full-width heating device that heats a steel sheet over an entire area in a width direction of the steel sheet, an edge heating device that heats end portions in the width direction of the steel sheet, and a cold rolling mill that rolls the steel sheet and that is arranged on a downstream side in a rolling direction with respect to the full-width heating device and the edge heating device. The method includes: a step of heating the steel sheet by using the full-width heating device and the edge heating device in such a manner that temperatures of the end portions in the width direction becomes higher than a temperature of a central portion in the width direction of the steel sheet on an entry side of the cold rolling mill. The temperatures of the central portion in the width direction and the end portions in the width direction of the steel sheet on the entry side of the cold rolling mill may change according to an Si content of the steel sheet. The temperatures of the central portion in the width direction and the end portions in the width direction of the