JP2001259723A - Method for controlling cooling of rolled stock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate the speed of response of cooling rate control in a cooling area. SOLUTION: When a steel sheet 2 which presses through the cooling area 3 on the outlet side of a hot finishing mill 1 is coiled by a coiling device 4, the surface temperature and average temperature in the thickness direction of the steel sheet 2 in the position of a thermometer 6 are estimated from the surface temperature and average temperature in the thickness direction of the steel sheet 2 in the cooling completing position in the cooling area 3 and the conveyance time to the steel sheet 2 from the cooling completing position to the thermometer 6 installed on the outlet side of the cooling area. Next, after correcting the estimated value of temperature in the position of the thermometer 6 by using the actual surface temperature of the steel sheet 2 measured with the thermometer 6, the surface temperature and average temperature in the thickness direction of the steel sheet 2 in the position of the coiling thermometer 5 are estimated on the basis of this correction value and the predicted conveyance time from the thermometer 6 to a coiling thermometer 5 and the cooling rate in the cooling area 3 is controlled so that the estimated value of temperature in the position of the coiling thermometer 5 coincides with the target coiling temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a cooling amount of a cooling area disposed on an outlet side of a hot finishing mill.

[0002]

2. Description of the Related Art Conventionally, when a steel sheet that has passed through a cooling area on the exit side of a hot finishing mill is wound by a winding device, a winding thermometer is located at a predetermined distance from the cooling area toward the winding device. (Usually a radiation thermometer), and the cooling amount of the cooling area (the amount of operation of an actuator or the like) is adjusted so that the measured surface temperature of the steel sheet measured by the winding thermometer matches the target winding temperature. I try to control.

[0003] The winding temperature is one of the indices of quality assurance of a steel sheet. In order to withstand the quality assurance, a stable winding temperature under various rolling conditions such as a steel sheet thickness, a rolling speed, and a cooling position is required. Measurement is required. For example, immediately after cooling in the cooling area, since the surface temperature of the steel sheet is relatively low, especially in a thick steel sheet, the heat inside the steel sheet is conducted to some extent in the thickness direction, and the temperature distribution in the thickness direction is in a quasi-steady state ( The measurement must be performed after the boundary condition (assuming atmospheric cooling). Therefore, the installation position of the winding thermometer needs to be a position sufficiently separated from the cooling area to the winding device side (for example, 20 to 30 m or more downstream from the cooling area).

[0004]

However, if the winding thermometer is installed at a position sufficiently separated from the cooling area to the winding device side as described above, a feedback control system for controlling the cooling amount of the cooling area is required. The constant (delay time) increases and the control gain cannot be increased, resulting in a disadvantage that the response speed of the cooling amount control becomes slow.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a disadvantage, and an object of the present invention is to provide a method for controlling the cooling of a rolled material, which can increase the response speed of controlling the amount of cooling in a cooling area.

[0006]

In order to achieve the above object, a method for controlling the cooling of a rolled material according to the present invention is directed to a rolled material passed through a cooling area on an outlet side of a hot finishing mill. In the method of controlling the cooling amount in the cooling area so that the temperature of the rolled material at a reference position separated from the cooling area by a predetermined distance from the cooling area to the winding device at the reference position matches the target winding temperature, From the surface temperature and the average temperature in the thickness direction of the rolled material at the cooling end position, and the transport time of the rolled material from the cooling end position to the thermometer installed on the cooling area exit side, the rolled material at the thermometer position After estimating the surface temperature and the average temperature in the thickness direction, and then correcting the estimated temperature at the thermometer position using the actual surface temperature of the rolled material measured by the thermometer, this correction value, From thermometer to the reference position The surface temperature and the average temperature in the thickness direction of the rolled material at the reference position are estimated based on the estimated transport time of the rolled material, and the temperature is cooled so that the estimated temperature at the reference position matches the target winding temperature. It is characterized in that the amount of cooling in the area is controlled.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram for explaining an example of equipment for implementing a cooling control method according to an embodiment of the present invention, FIG. 2 is a graph showing an example of a temperature history of a steel sheet,
FIG. 3 is a graph for explaining a calculation example of the temperature estimation value at the cooling area outlet thermometer position, and FIG. 4 is a graph for explaining a correction example of the temperature estimation value at the cooling area outlet thermometer position. FIG. 5 and FIG. 5 are graphs for explaining a calculation example of the estimated value of the steel sheet temperature at the position of the winding thermometer.

In FIG. 1, reference numeral 1 denotes a hot finish rolling mill. A steel sheet 2 having passed through the rolling mill 1 passes through a cooling area 3 and is wound by a winding device 4. The cooling of the steel sheet 2 in the cooling area 3 is performed using a part of the cooling area 3, and the winding temperature of the steel sheet 2 is controlled by adjusting the amount of cooling water. Further, the winding temperature is measured and managed by a winding thermometer 5 installed in a quasi-steady state region, which will be described later, upstream of the winding device 4. In this embodiment, the installation position of the winding thermometer 5 is defined as a reference position according to the present invention.

In this embodiment, a thermometer 6 is installed immediately downstream of the cooling area 3 on the outlet side, and a controller (not shown) uses the measured value of the thermometer 6 to control the temperature in the cooling area 3. The amount of cooling water is controlled by adjusting the operation amount of the cooling actuator. FIG. 2 shows an example of the history of the average temperature in the thickness direction and the surface temperature of the steel sheet 2 after passing through the rolling mill 1.

As can be seen from this figure, both the average temperature in the thickness direction and the surface temperature of the steel sheet 2 are lowered by water cooling in the cooling area 3, and the amount of temperature drop at this time is larger for the surface temperature. When the water cooling of the steel sheet 2 in the cooling area 3 is completed, the average temperature in the thickness direction of the steel sheet 2 further decreases though it is small to a small degree due to the air cooling, but the surface temperature of the steel sheet 2 from the center in the thickness direction of the steel sheet 2 decreases. Conduction wins over atmospheric cooling,
Rise for a while. After a certain time elapses, the boundary condition becomes a quasi-steady state in the air cooling, and the average temperature and the surface temperature in the thickness direction of the steel plate 2 both decrease while asymptotically approaching. In this embodiment, the surface temperature of the steel plate 2 is measured by the thermometer 6 on the cooling area outlet side before the boundary condition becomes a quasi-steady state in the air cooling.
The amount of cooling water in the cooling area 3 is operated by the controller using the measured values of the above.

Next, the operation of the controller will be described. First, referring to FIG. 3, the average temperature 1a ₁ and surface temperature Θs ₁ in the thickness direction of steel sheet 2 at the water-cooling end position are set as initial values, and steel sheet 2 at the cooling area outlet thermometer 6 positions after water cooling is ended. Transfer time, ie, a function of time t _{1 obtained} by subtracting the water cooling end time from the measurement time (current time) of the steel sheet temperature measured by the cooling area outlet thermometer 6 and the cooling specification (cooling rate, etc.) The average temperature 計算 a ₂ and the surface temperature Θs _{2 in} the thickness direction of the steel plate 2 at the installation position of the cooling area outlet thermometer 6 using the heat transfer calculation model formula having parameters such as
Is estimated. The average temperature Θa ₁ and the surface temperature Θs _{1 in} the thickness direction of the steel sheet 2 at the water cooling end position can be calculated using the heat transfer calculation model formula from the water cooling results such as the amount of water cooling in the cooling area 3 and the transfer time. as a method, the cooling rate of water cooling the steel sheet, the steel sheet thickness, the difference between the average in the thickness direction temperature .THETA.a ₁ and the surface temperature .THETA.s ₁ of the steel plate 2 (Θa ₁ -Θs
₁ ) can be easily calculated. Incidentally, in the later calculations, it is sufficient that the difference between the average temperature Θa _{1 in} the steel sheet thickness direction and the surface temperature Θs ₁ can be calculated for the time being.

Next, referring to FIG. 4, the estimated average temperature Θa ₂ and the estimated surface temperature Θs ₂ in the thickness direction of the steel sheet 2 at the installation position of the cooling area outlet thermometer 6 are measured by the cooling area outlet thermometer 6. Measured value of steel plate 2 surface (actual surface temperature) Θf
It corrected using the, .THETA.s corrected mean temperature .THETA.a ₂ in the thickness direction 'and the corrected surface temperature _{Θs 2' 2 '= Θf,} Θa 2' = Θ
It is calculated by _{a 2 + (Θs 2 '-Θs} 2).

Next, referring to FIG. 5, the corrected average temperature Θa ₂ ′ and the corrected surface temperature Θs ₂ ′ in the thickness direction of the steel plate 2 at the installation position of the cooling area outlet thermometer 6 are used as initial values. The average temperature in the thickness direction of the steel sheet 2 at the installation position of the winding thermometer 5 based on the value and the predicted transport time t ₂ of the steel sheet 2 from the cooling area outlet thermometer 6 to the winding thermometer 5 Θa ₃ And the surface temperature Δs ₃ are estimated. Note that the predicted transport time t ₂ can be easily estimated by calculating the expected arrival time of the steel sheet 2 at the position of the winding thermometer 5 using the speed pattern prediction model formula from the rolling conditions of the steel sheet.

Next, the steel sheet 2 at the installation position of the winding thermometer 5
In order to eliminate the deviation by comparing the estimated average temperature Θa _{3 in} the thickness direction with the target winding temperature, the operation amount of the cooling actuator in the cooling area 3 is adjusted to control the amount of cooling water and thus the winding temperature. As described above, in this embodiment, the amount of cooling in the cooling area 3 is controlled using the measurement value of the thermometer 6 installed on the outlet side of the cooling area 3, so that the time constant of the feedback control system is controlled. (Delay time) is reduced, and the control gain can be increased. As a result, the response speed of the cooling amount control can be significantly increased.

[0015]

As is apparent from the above description, according to the present invention, it is possible to increase the response speed of the cooling amount control in the cooling area arranged on the outlet side of the hot finishing mill. can get.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining an example of equipment for implementing a cooling control method according to an embodiment of the present invention.

FIG. 2 is a graph showing an example of a temperature history of a steel sheet.

FIG. 3 is a graph for explaining a calculation example of a temperature estimation value at a cooling area outlet thermometer position.

FIG. 4 is a graph for explaining a correction example of a temperature estimation value at a cooling area outlet thermometer position.

FIG. 5 is a graph for explaining a calculation example of an estimated value of a steel sheet temperature at a winding thermometer position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hot finishing rolling mill 2 ... Steel plate (rolled material) 3 ... Cooling area 4 ... Winding device 5 ... Winding thermometer 6 ... Cooling area outlet thermometer

Claims (1)

[Claims] When a rolled material that has passed through a cooling area on an outlet side of a hot finishing rolling mill is wound by a winding device, the rolled material at a reference position separated from the cooling area by a predetermined distance to the winding device side. In a method for controlling a cooling amount in a cooling area so that a temperature matches a target winding temperature, a surface temperature and a thickness direction average temperature of a rolled material at a cooling end position of the cooling area, and a cooling area from the cooling end position. From the transport time of the rolled material to the thermometer installed on the outlet side, the surface temperature and the average thickness direction temperature of the rolled material at the thermometer position are estimated, and then the estimated temperature value at the thermometer position is calculated. After correcting using the actual surface temperature of the rolled material measured by the thermometer, based on this correction value and the estimated transport time of the rolled material from the thermometer to the reference position, Surface temperature and thickness of rolled material The average temperature is estimated and cooling control method of the rolled material to a temperature estimate at the reference position and controls the amount of cooling in the cooling area to match the target coiling temperature.