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 transverse-type full-width heating device that heats a steel sheet over an entire area in a 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 transverse-type full-width heating device, the method includes: heating the steel sheet by using the transverse-type full-width heating device in such a manner that temperatures of 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.

1 .- 7 . (canceled) 
     
     
         8 . A manufacturing method of a cold-rolled steel sheet in which the method uses a transverse-type full-width heating device that heats a steel sheet over an entire area in a 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 transverse-type full-width heating device, the method comprising:
 heating the steel sheet by using the transverse-type full-width heating device in such a manner that temperatures of 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.   
     
     
         9 . The manufacturing method of the cold-rolled steel sheet according to  claim 8 , 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 change according to an Si content of the steel sheet. 
     
     
         10 . The manufacturing method of the cold-rolled steel sheet according to  claim 8 , 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 
 
     
     
         11 . The manufacturing method of the cold-rolled steel sheet according to  claim 9 , 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 
 
     
     
         12 . Manufacturing equipment of a cold-rolled steel sheet, the equipment comprising:
 a transverse-type full-width heating device that heats a steel sheet over an entire area in a 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 transverse-type full-width heating device, wherein   the transverse-type full-width heating device heats the steel sheet in such a manner that temperatures of 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.   
     
     
         13 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 12 , wherein the transverse-type full-width heating device changes 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 according to an Si content of the steel sheet. 
     
     
         14 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 12 , wherein the transverse-type full-width heating device heats 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 
 
     
     
         15 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 13 , wherein the transverse-type full-width heating device heats 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 
 
     
     
         16 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 12 , wherein the transverse-type full-width heating device is installed at a position within 10 m from the entry side of the cold rolling mill. 
     
     
         17 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 13 , wherein the transverse-type full-width heating device is installed at a position within 10 m from the entry side of the cold rolling mill. 
     
     
         18 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 14 , wherein the transverse-type full-width heating device is installed at a position within 10 m from the entry side of the cold rolling mill. 
     
     
         19 . The manufacturing equipment of the cold-rolled steel sheet according to  claim 15 , wherein the transverse-type full-width heating device is installed at a position within 10 m from the entry side of the cold rolling mill.