Manufacturing apparatus of hot-rolled steel sheet and manufacturing method of hot rolled steel sheet

1. A manufacturing apparatus of a hot-rolled steel sheet comprising:

a row of hot finishing mills;

an immediate rapid-cooling device, which is disposed on an exit side of a final stand in the row of hot finishing mills, and at least a part of which is disposed inside the final stand so as to be capable of spraying cooling water;

a device for measuring a temperature on an entry side of a final stand, which is arranged in a manner capable of measuring a surface temperature of a steel sheet on an entry side of the final stand;

a device for measuring a steel sheet passing speed, which is arranged in a manner capable of measuring a passing speed of the steel sheet on the entry side of the final stand;

a device for predicting a rapid-cooling stopping temperature, which calculates a predicted rapid-cooling stopping temperature based on: the surface temperature of the steel sheet measured by the device for measuring a temperature on an entry side of a final stand; the steel sheet passing speed measured by the device for measuring the steel sheet passing speed; and the water supply volume or water supply pressure of the immediate rapid-cooling device; and

an immediate rapid-cooling control device, which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device such that the predicted rapid-cooling stopping temperature matches a targeted rapid-cooling stopping temperature.

2. A manufacturing method of a hot-rolled steel sheet using the manufacturing apparatus of a hot-rolled steel sheet according to claim 1 , wherein with a measured value of the steel sheet temperature on the entry side of the final stand as an initial value, the predicted rapid-cooling stopping temperature is calculated based on the surface temperature of the steel sheet and the water supply volume or water supply pressure of the immediate rapid-cooling device; and

the water supply volume or water supply pressure of the immediate rapid-cooling device is corrected such that the predicted rapid-cooling stopping temperature matches a targeted rapid-cooling stopping temperature.

3. A manufacturing apparatus of a hot-rolled steel sheet comprising:

a row of hot finishing mills;

an immediate rapid-cooling device, which is disposed on an exit side of a final stand in the row of hot finishing mills, and at least a part of which is disposed inside the final stand so as to be capable of spraying cooling water;

a device for measuring a temperature on an entry side of a final stand, which is arranged in a manner capable of measuring a surface temperature of a steel sheet on an entry side of the final stand;

a device for measuring a temperature on an exit side of an immediate rapid-cooling device, which is arranged in a manner capable of measuring the surface temperature of the steel sheet on an exit side of the immediate rapid-cooling device;

a device for measuring a steel sheet passing speed, which is arranged in a manner capable of measuring a passing speed of the steel sheet on the entry side of the final stand;

a device for predicting a rapid-cooling stopping temperature, which calculates a predicted rapid-cooling stopping temperature based on the surface temperature of the steel sheet measured by the device for measuring a temperature on an entry side of a final stand, the steel sheet passing speed measured by the device for measuring a steel sheet passing speed, and the water supply volume or water supply pressure of the immediate rapid-cooling device; and

an immediate rapid-cooling control device, which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device such that the predicted rapid-cooling stopping temperature matches a targeted rapid-cooling stopping temperature, until a top portion of the steel sheet passes through the immediate rapid-cooling device, and which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device, or the steel sheet passing speed such that the temperature measured by the device for measuring a temperature on an exit side of an immediate rapid-cooling device matches the targeted rapid-cooling stopping temperature, after the top portion of the steel sheet passes through the immediate rapid-cooling device.

4. A manufacturing method of a hot-rolled steel sheet using the manufacturing apparatus of a hot-rolled steel sheet according to claim 3 , wherein until the top portion of the steel sheet passes through the immediate rapid-cooling device, with a measured value of the steel sheet temperature on the entry side of the final stand as an initial value, the predicted rapid-cooling stopping temperature is calculated based on the surface temperature of the steel sheet and the water supply volume or water supply pressure of the immediate rapid-cooling device, and the water supply volume or water supply pressure of the immediate rapid-cooling device is corrected such that the predicted rapid-cooling stopping temperature matches a targeted rapid-cooling stopping temperature; and

after the top portion of the steel sheet passes through the immediate rapid-cooling device, the water supply volume or water supply pressure of the immediate rapid-cooling device, or the steel sheet passing speed is corrected such that the measured value by the device for measuring a temperature on an exit side of an immediate rapid-cooling device matches the targeted rapid-cooling stopping temperature.

5. A manufacturing apparatus of a hot-rolled steel sheet comprising:

a row of hot finishing mills;

an immediate rapid-cooling device, which is disposed on an exit side of a final stand in the row of hot finishing mills, and at least a part of which is disposed inside the final stand so as to be capable of spraying cooling water;

a hot-run cooling device, which is disposed on an outer side of the immediate rapid-cooling device;

a device for measuring a temperature on an entry side of a final stand, which is arranged in a manner capable of measuring a surface temperature of a steel sheet on an entry side of the final stand;

a device for measuring a steel sheet passing speed, which is arranged in a manner capable of measuring a passing speed of the steel sheet on the entry side of the final stand;

a device for predicting a rapid-cooling stopping temperature/coiling temperature, which calculates a predicted rapid-cooling stopping temperature and predicted coiling temperature based on: the surface temperature of the steel sheet measured by the device for measuring a temperature on an entry side of a final stand; the steel sheet passing speed measured by the device for measuring a steel sheet passing speed; the water supply volume or water supply pressure of the immediate rapid-cooling device; and the water supply volume of the hot-run cooling device; and

an immediate rapid-cooling/hot-run cooling control device, which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device such that the predicted rapid-cooling stopping temperature and predicted coiling temperature match a targeted rapid-cooling stopping temperature and targeted coiling temperature.

6. A manufacturing method of a hot-rolled steel sheet using the manufacturing apparatus of a hot-rolled steel sheet according to claim 5 , wherein with a measured value of the steel sheet temperature on the entry side of the final stand as an initial value, the predicted rapid-cooling stopping temperature and predicted coiling temperature are calculated based on the surface temperature of the steel sheet, the water supply volume or water supply pressure of the immediate rapid-cooling device, and the water supply volume of the hot-run cooling device; and

the water supply volume or water supply pressure of the immediate rapid-cooling device is corrected and the water supply volume of the hot-run cooling device is corrected, such that the predicted rapid-cooling stopping temperature and predicted coiling temperature match a targeted rapid-cooling stopping temperature and targeted coiling temperature.

7. A manufacturing apparatus of a hot-rolled steel sheet comprising:

a row of hot finishing mills;

an immediate rapid-cooling device, which is disposed on an exit side of a final stand in the row of hot finishing mills, and at least a part of which is disposed inside the final stand so as to be capable of spraying cooling water;

a hot-run cooling device, which is disposed on an outer side of the immediate rapid-cooling device;

a device for measuring a temperature on an entry side of a final stand, which is arranged in a manner capable of measuring a surface temperature of a steel sheet on an entry side of the final stand;

a device for measuring a temperature on an exit side of an immediate rapid-cooling device, which is arranged in a manner capable of measuring the surface temperature of the steel sheet on an exit side of the immediate rapid-cooling device;

a device for measuring a steel sheet passing speed, which is arranged in a manner capable of measuring a passing speed of the steel sheet on the entry side of the final stand;

a device for predicting a rapid-cooling stopping temperature/coiling temperature, which calculates a predicted rapid-cooling stopping temperature and predicted coiling temperature based on: the surface temperature of the steel sheet measured by the device for measuring a temperature on an entry side of a final stand; the steel sheet passing speed measured by the device for measuring a steel sheet passing speed; the water supply volume or water supply pressure of the immediate rapid-cooling device; and the water supply volume of the hot-run cooling device; and

an immediate rapid-cooling/hot-run cooling control device, which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device and the water supply volume of the hot-run cooling device such that the predicted rapid-cooling stopping temperature and predicted coiling temperature match a targeted rapid-cooling stopping temperature and targeted coiling temperature, until a top portion of the steel sheet passes through the immediate rapid-cooling device, and which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device, or the steel sheet passing speed such that the temperature measured by the device for measuring a temperature on an exit side of an immediate rapid-cooling device matches the targeted rapid-cooling stopping temperature, and corrects the water supply volume of the hot-run cooling device such that the predicted coiling temperature matches the targeted coiling temperature, after the top portion of the steel sheet passes through the immediate rapid-cooling device.

8. A manufacturing method of a hot-rolled-steel sheet using the manufacturing apparatus of a hot-rolled steel sheet according to claim 7 , wherein until the top portion of the steel sheet passes through the immediate rapid-cooling device, with a measured value of the steel sheet temperature on the entry side of the final stand as an initial value, the predicted rapid-cooling stopping temperature and predicted coiling temperature are calculated based on the surface temperature of the steel sheet, the water supply volume or water supply pressure of the immediate rapid-cooling device, and the water supply volume of the hot-run cooling device; and the water supply volume or water supply pressure of the immediate rapid-cooling device is corrected and the water supply volume of the hot-run cooling device is corrected, such that the predicted rapid-cooling stopping temperature and predicted coiling temperature match a targeted rapid-cooling stopping temperature and targeted coiling temperature; and

after the top portion of the steel sheet passes through the immediate rapid-cooling, the water supply volume or water supply pressure of the immediate rapid-cooling device, or the steel sheet passing speed is corrected such that the temperature measured by the device for measuring a temperature on an exit side of an immediate rapid-cooling device matches the targeted rapid-cooling stopping temperature, and the water supply volume of the hot-run cooling device is corrected such that the predicted coiling temperature matches the targeted coiling temperature.