JP2001334305A - Method for controlling finishing temperature of steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling the finishing temperature of a steel sheet for making the finishing temperature of the whole steel sheet more accurately coincide with the target value of the finishing temperature. SOLUTION: The target value of temperature on the inlet side of a heating device 2 is calculated from the target value of the finishing temperature of a rough bar 1 on the outlet side of a finishing rolling mill 3 and the deviation between this target value of temperature and the value of temperature detected with a temperature detecting device 5 which is installed on the inlet side of an induction heating device 2 is calculated. In the case that this deviation is positive, the temperature of the rough bar 1 is raised with the induction heating device 2 and, in the case that the temperature rise exceeds the temperature raising capacity of the induction heating device 2, the amount of cooling spray from cooling sprays 4 is reduced. In the case that the deviation is negative, the amount of the cooling spray from the cooling sprays 4 is increased. In this manner, the finishing temperature of the rough bar 1 is controlled so as to make it coincide with the target value of the finishing 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 finishing temperature of a steel sheet.

[0002]

2. Description of the Related Art In continuous hot finish rolling, it is well known that the metallurgical and mechanical properties of a steel strip vary greatly depending on the rolling temperature. In particular, when a slab made of carbon steel is continuously hot-rolled, from the viewpoint of securing the material, the rolling temperature in the finish rolling mill is set to the ferrite transformation start temperature (A
r3 temperature). Ar3 during rolling
If the temperature is lower than the transformation temperature, properties such as strength, ductility, and toughness of the steel strip may deteriorate due to accumulation of coarse grains and strain.

In recent years, continuous hot finish rolling tends to be longer in order to improve productivity. For this reason, it is said that a reduction in the rolling temperature in the longitudinal direction of the steel strip can be prevented to some extent by shortening the time required to pass between rolling mills.

In Japanese Patent Application Laid-Open No. 55-30338, an induction heating furnace is provided between the exit side of a rough rolling mill and the entrance side of a finishing rolling mill to heat a rear end portion of a steel strip in a longitudinal direction. There is disclosed a method for preventing a decrease in temperature. Here, a method is employed in which an induction heating furnace having a small heating time constant is used, and the temperature is controlled according to the deviation between the finishing temperature delivery side and its target temperature.

[0005]

In accelerated rolling, the rolling speed reaches the upper limit at the trailing end of a long slab, and it cannot be completely solved.

On the other hand, the method disclosed in Japanese Patent Application Laid-Open No. 55-30338 can solve the situation caused by the accelerated rolling to some extent. In order to control the induction heating furnace, the temperature cannot be controlled until the leading end of the rolled material leaves the finishing mill.

[0007] Further, there is a situation that it is extremely difficult to match the finishing temperature target value over the entire longitudinal direction because a control delay is large and a control system with good response cannot be made.

[0008] Further, no consideration is given to a control method when a heating amount exceeding the heating capacity of the induction heating device is required, or when the temperature of the coarse bar is high and cooling is required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for controlling a finishing temperature of a steel sheet which can more accurately match the finishing temperature of the entire steel sheet to a target finishing temperature value. To provide.

[0010]

In order to achieve the above object, a method for controlling a finishing temperature of a steel sheet according to the present invention comprises:
In the aspect, the target temperature at the entrance of the heating device is calculated from the target temperature of the finishing temperature at the exit of the finishing mill, and the target temperature and the temperature detected by the temperature detector installed at the entrance of the heating device are calculated. Calculate the deviation from the detected value. If the deviation is positive, increase the heating amount of the heating device that heats the steel plate, and decrease the cooling amount of the cooling device if a heating amount that exceeds the heating capability of the heating device is required. Let it. On the other hand, when the deviation is negative, the cooling amount of the cooling device is increased.

[0011] According to such a steel sheet finishing temperature control method, according to the deviation between the target temperature of the steel sheet at the entrance of the heating device and the detected temperature of the steel plate actually detected at the entrance of the heating device, The heating amount of the heating device and the cooling amount of the cooling device are determined. For this reason, it is possible to more accurately match the finishing temperature of the entire steel sheet with the finishing temperature target value.

In a second aspect of the method for controlling a finishing temperature of a steel sheet according to the present invention, a target temperature value at a heating device output side is calculated from a finishing temperature target value at a finishing rolling mill output side, and the heating device is controlled. An estimated temperature value at the outlet of the heating device is calculated from a detected temperature value detected by a temperature detector installed on the inlet side, and a deviation between the estimated temperature value and the target temperature value is calculated. If the deviation is positive, increase the heating amount of the heating device that heats the steel plate, and decrease the cooling amount of the cooling device if a heating amount that exceeds the heating capability of the heating device is required. Let it. On the other hand, when the deviation is negative, the cooling amount of the cooling device is increased.

[0013] According to such a steel sheet finishing temperature control method, the heating device is raised in accordance with the deviation between the estimated temperature of the steel plate on the exit side of the heating device and the target temperature of the steel sheet on the entrance side of the heating device. The amount of heat and the amount of cooling of the cooling device are determined.

In particular, depending on the estimated temperature at the outlet of the heating device,
Since the temperature of the entire steel sheet is controlled so as to coincide with the finish temperature target value, the accuracy is further improved.

In a third aspect of the method for controlling the finishing temperature of a steel sheet according to the present invention, the finishing temperature target value on the exit side of the finishing rolling mill and the temperature detected by the temperature detector installed on the exit side of the finishing rolling mill are detected. Calculate the deviation from the detected temperature value. And
If the deviation is positive, the heating device is feedback-controlled in the direction in which the heating amount increases, and if the heating amount including this feedback amount exceeds the heating capability of the heating device, the cooling amount of the cooling device is Decrease. On the other hand, when the deviation is negative, the heating device is feedback-controlled in a direction in which the heating amount decreases, and when the heating amount including the feedback amount becomes zero or lower than the minimum heating amount, the heating device is cooled. Increase equipment cooling.

According to such a steel sheet finishing temperature control method, the deviation between the finishing temperature target value on the exit side of the finishing rolling mill and the temperature detection value detected by the temperature detector installed on the finishing rolling mill exit side. , The amount of temperature rise of the heating device and the amount of cooling of the cooling device are determined.

In particular, the heating device and the cooling device are feedback-controlled in accordance with the detected temperature value actually detected on the heating device outlet side. The finishing temperature can be made to match the finishing temperature target value. For this reason, the accuracy is controlled by the first mode in which the temperature is controlled in accordance with the temperature detection value actually detected in the heating device, or the second mode in which the temperature is controlled in accordance with the temperature estimation value estimated in the heating device. It is higher than in the second embodiment.

In the fourth aspect of the method for controlling the finishing temperature of a steel sheet according to the present invention, the finishing temperature target value on the exit side of the finishing rolling mill is detected by a temperature detector installed between the finishing rolling mills. The deviation from the detected temperature value is calculated. When the deviation is positive, the heating device is feedback-controlled in a direction in which the heating amount increases, and when the heating amount including the feedback amount exceeds the heating capability of the heating device,
Reduce the amount of cooling in the cooling device. On the other hand, when the deviation is negative, the heating device is feedback-controlled in a direction in which the amount of temperature rise is reduced, and when the amount of temperature rise including this feedback amount becomes zero or lower than the minimum amount of temperature rise, the cooling device is controlled. Increase the amount of cooling.

According to such a steel sheet finishing temperature control method, the deviation between the finishing temperature target value on the exit side of the finishing rolling mill and the temperature detection value detected by the temperature detector installed between the finishing rolling mills. The amount of temperature rise of the heating device and the amount of cooling of the cooling device are determined in accordance with the deviation from.

In particular, since the heating device and the cooling device are feedback-controlled in accordance with the detected temperature value actually detected in the finishing mill, the finishing of the steel sheet can be performed while responding to the actual temperature change in the finishing mill. The temperature can be matched to the finishing temperature target. For this reason, the accuracy is controlled by the first mode in which the temperature is controlled in accordance with the temperature detection value actually detected in the heating device, or the second mode in which the temperature is controlled in accordance with the temperature estimation value estimated in the heating device. It is higher than in the second embodiment.

In a fifth aspect of the method for controlling the finishing temperature of a steel sheet according to the present invention, a target temperature value at a heating device outlet side is calculated from a finishing temperature target value at a finishing rolling mill outlet side. A deviation between the target value and a temperature detection value detected by a temperature detector installed on the outlet side of the heating device is calculated. When the deviation is positive, the heating device is feedback-controlled in a direction in which the heating amount increases, and when the heating amount including the feedback amount exceeds the heating capability of the heating device, the cooling device is controlled. Reduce the amount of cooling. On the other hand, when the deviation is negative, the heating device is feedback-controlled in a direction in which the heating amount decreases, and when the heating amount including the feedback amount becomes zero or lower than the minimum heating amount, the heating device is cooled. Increase equipment cooling.

According to such a steel sheet finishing temperature control method, a temperature target value at the outlet of the heating device and a temperature detected value detected by a temperature detector installed at the outlet of the heating device are determined in accordance with a deviation. , The heating amount of the heating device and the cooling amount of the cooling device are determined.

In particular, the heating device and the cooling device are feedback-controlled in accordance with the detected temperature value actually detected on the heating device outlet side. The finishing temperature can be made to match the finishing temperature target value. For this reason, the accuracy is controlled by the first mode in which the temperature is controlled in accordance with the temperature detection value actually detected in the heating device, or the second mode in which the temperature is controlled in accordance with the temperature estimation value estimated in the heating device. It is higher than in the second embodiment.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steel sheet finishing temperature control apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a view showing a basic configuration of a steel plate rolling apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the coarse bar 1 is heated while moving in the induction heating device 2. Induction heating device 2
Is installed on the entry side of the finishing mill group 3. The rough bar 1 that has passed through the induction heating device 2 is finally rolled by the finishing mill group 3 to the thickness of the product. Finishing rolling mill group 3
Is provided with a cooling spray 4 and is used to cool the coarse bar 1 while rolling. The cooling spray 4
Specifically, they are installed between the finishing mills and before and after the finishing mills, respectively. A temperature detector 5 for detecting the temperature of the coarse bar 1 is installed near the inlet side of the induction heating device 2.

When the tip of the coarse bar 1 passes through the temperature detector 5, the detected temperature is usually 900 ° C. or higher. For this reason,
By constantly monitoring the detected temperature value, the passage of the coarse bar 1 can be determined. At this time, the moving distance of the coarse bar 1 can be calculated by using a speed detected by a transport speed detector (not shown) of the coarse bar 1 and integrating the speed.
Until the moving distance of the coarse bar 1 reaches a predetermined length, temperature detection is performed at a constant sampling cycle, and when the length reaches the predetermined length, an average of all sampled temperature detection values is calculated. Is the representative temperature of the predetermined length.
This process is performed until the rear end of the rough bar 1 passes through the temperature detector 5.

On the other hand, the tip of the rough bar 1 continues to move,
Although the movement reaches the induction heating device 2, by continuing to calculate the movement distance, it is possible to detect the timing at which the leading end and the subsequent predetermined length portion enter the induction heating device 2.
By tracking the position of the rough bar 1 in this way, when the rough bar 1 enters the induction heating device 2, the corresponding portion can be heated at a predetermined temperature rising amount.

Further, in order to calculate the amount of temperature rise in the induction heating device 2 and the amount of temperature decrease in the cooling spray 4, the induction heating device 2 is calculated based on the finishing temperature target value at the exit side of the finishing mill group 3. Calculate the temperature target value at the entry side of. For example, as described in “Sheet Rolling Theory and Practice (edited by the Iron and Steel Institute of Japan), pp. 141-160”, the following can be obtained.

Since the length of the steel sheet at the time of hot rolling is sufficiently longer than the thickness and the width, the temperature distribution of the steel sheet only needs to be considered in the thickness direction. The heat conduction equation considering only the thickness direction is

[0031]

(Equation 1)

## EQU2 ##

Where α _s = λ _s / (σ _ε c _s ),
T _s : temperature of steel sheet, λ _s : thermal conductivity, ρ _s : density, c _s : specific heat, q: calorific value per unit volume / unit time, t: time, y: coordinate in the thickness direction of the steel sheet, It is.

Heat generation and heat removal during hot rolling are given as follows.

1) Temperature drop in the air cooling section

[0036]

(Equation 2)

[0037]

(Equation 3)

Where q _{r is the} heat flux due to radiant heat transfer,
ε: emissivity, T _su : surface temperature, T _a : atmospheric temperature, σ: Stefan-Boltzmann constant, q _c : heat flux by convective heat transfer, h _c : convective heat transfer coefficient.

2) Temperature drop in water cooling section

[0040]

(Equation 4)

Here, q _w : heat flux by water cooling, h _w : heat transfer coefficient of water cooling, Tw: water temperature.

3) Heat generated during processing The heat generated during processing when the sheet thickness is rolled from h ₁ to h ₂ is represented by the following equation.

[0043]

(Equation 5)

Where Q _{p is the} amount of heat generated by plastic deformation,
A: heat equivalent of work, k: two-dimensional deformation resistance.

4) Heat generation due to friction The heat generated by friction due to relative slip between the steel sheet and the roll during rolling is represented by the following equation.

[0046]

(Equation 6)

Here, Q _{f is the} amount of heat generated by friction, μ is the coefficient of friction, and p _{m is the} average rolling pressure. Ν ⁻ _r is
The average value of the absolute value of the relative speed between the roll and the steel sheet, which is expressed by the following equation.

[0048]

(Equation 7)

[0049]

(Equation 8)

Here, ν _R : roll peripheral speed, f: advance rate, b: reverse rate, r: reduction rate. Further, t
_r is the contact time between the roll and the steel sheet, and is calculated using the following approximate expression.

[0051]

(Equation 9)

Here, R is a roll radius.

5) Contact heat conduction by roll The amount of heat conducted from the steel plate to the roll is represented by the following equation.

[0054]

(Equation 10)

[0055]

[Equation 11]

[0056]

(Equation 12)

Where, Q _R : calorific value of the contact heat conduction by the roll, T _so : initial temperature of the steel sheet, π: circumference, λ _R : thermal conductivity of the roll, ρ _R : roll density, c _R : specific heat of the roll. ,.

That is, using these equations (1) to (12), the rough bar temperature estimation calculation from the induction heating device outlet side to the finish rolling mill outlet side is performed. Further, in order to calculate the temperature target value at the outlet side of the induction heating device 2 from the finishing target temperature, an appropriate induction heating device outlet side temperature is given, and the estimated temperature at the finish rolling mill outlet side becomes the finishing target temperature. Convergence calculation is performed so that they match.

When a certain part of the coarse bar passes through a temperature detector installed on the inlet side of the induction heating device, when the deviation between the target temperature of the part and the temperature detected by the temperature detector is positive,
This deviation is the amount of temperature rise in the induction heating device. That is,

[0060]

(Equation 13)

When ΔT _ie > 0,

[0062]

[Equation 14]

Is obtained.

When ΔT _ie <0,

[0065]

(Equation 15)

Is expressed as follows. Where ΔT _ie : temperature deviation,
T _ir : target temperature at the induction heating device entrance side, T _ij : detected temperature at the induction heating device entrance side, ΔT _BH : temperature rise amount at the induction heating device, ΔT _sp : cooling temperature at the spray.

At this time, the electric energy in the induction heating device is given by, for example, the following equation.

[0068]

(Equation 16)

[0069] However, Q _r: power supplied to the induction heating device, S _b: cross-sectional area of the coarse bar, [nu _b: rough bar heating device passing speed, s: coarse bar density, c _p: crude Bar Specific heat.

[0070] However, if the power amount Q _r becomes a value above the ability of the induction heating device, the heating becomes insufficient, it will not reach the target temperature finish finishing temperature. Therefore, if the power amount Q _r exceeds the heating capacity of the induction heating device reduces the cooling spray amount of rolling mill finishing Atsushi Nobori of the heating shortfall, reducing the temperature drop in the finishing rolling mill Thereby, the temperature at the exit side of the finishing rolling mill is made to coincide with the target temperature.

That is, when ΔT _BH > ΔT _MAX ,

[0072]

[Equation 17]

Assume that: Here, ΔT _MAX is the maximum amount of temperature rise in the induction heating device. This makes it possible to control the temperature of the entire rough bar 1 so as to match the finishing temperature.

Hereinafter, some embodiments of the present invention will be described.
The following description focuses on the differences from the first embodiment.

[Second Embodiment] FIG. 2 is a view showing a basic configuration of a steel sheet rolling apparatus according to a second embodiment of the present invention.

As shown in FIG. 2, a temperature detector 5 for detecting the temperature of the coarse bar 1 is installed near the inlet side of the induction heating device 2.

From the target temperature value of the rough bar 1 at the output side of the finishing mill 3, the target temperature value at the output side of the induction heating device 2 is estimated using the above equations (1) to (12). Then, when a predetermined portion of the coarse bar 1 passes through the temperature detector on the input side of the induction heating device 2, the rough bar temperature on the output side of the induction heating device 2 is calculated from the temperature detection value according to the equations (1) to (1). Estimate using 3). The deviation between the target temperature at the outlet side of the induction heating device 2 and the estimated temperature at the outlet side of the induction heating device 2 is calculated. When the deviation is positive, the deviation is the amount of temperature rise in the induction heating device 2. That is,

[0078]

(Equation 18)

When ΔT _be > 0,

[0080]

[Equation 19]

Is obtained. When ΔT _be <0,

[0082]

(Equation 20)

Is represented by Where ΔT_be: Temperature deviation,
T_br: Induction heating device outlet side target temperature, T _br： Induction heating device
Estimated outlet temperature, ΔT_BH： Temperature rise in induction heating device, ΔT
_sp: Cooling temperature in spray.

At this time, the electric energy in the induction heating device is given by the following equation, for example.

[0085]

(Equation 21)

Where Q _{r is the} amount of electric power supplied to the heating device,
S _b : cross-sectional area of the heated material, ν _b : speed of the heated material passing through the heating device, s: density of the heated material, c _p : specific heat of the heated material.

[0087] However, if the power amount Q _r becomes a value above the ability of the induction heating device, the heating becomes insufficient, it will not reach the target temperature finish finishing temperature. Therefore, if the power amount Q _r exceeds the heating capacity of the induction heating device reduces the cooling spray amount of rolling mill finishing Atsushi Nobori of the heating shortfall, reducing the temperature drop in the finishing rolling mill Thereby, the temperature at the exit side of the finishing rolling mill is made to coincide with the target temperature.

That is, when ΔT _BH > ΔT _MAX ,

[0089]

(Equation 22)

Assume that Here, ΔT _MAX is the maximum amount of temperature rise in the induction heating device. This makes it possible to control the temperature of the entire rough bar 1 so as to match the finishing temperature.

[Third Embodiment] FIG. 3 is a view showing a basic configuration of a steel sheet rolling apparatus according to a third embodiment of the present invention.

As shown in FIG. 3, a temperature detector 6 for detecting the temperature of the rough bar 1 is provided near the exit side of the finishing mill group 3.

Immediately after the leading end of the steel material passes through the finishing mill group 3, the temperature detected by the temperature detector 6 installed on the outlet side of the finishing mill group 3, the target temperature assumed on the rough bar 1, and Is calculated, and the output of the induction heating device 2 is fed back. That is,

[0094]

(Equation 23)

The feedback amount is

[0096]

(Equation 24)

Is represented by Here, ΔT _fb : feedback heating amount, T _fr : finishing target temperature, T _fj : finishing temperature detection value, P _fb : feedback power amount, _KBH : feedback gain.

At this time, if the amount of temperature rise in the induction heating device including the feedback amount exceeds the heating capability of the induction heating device, the amount of insufficient heating is reduced by reducing the amount of cooling spray between the finishing mills. By reducing the temperature drop in the finishing mill, the temperature at the exit side of the finishing mill is made to coincide with the target temperature.

That is, when ΔT _BH + ΔT _fb > ΔT _MAX ,

[0100]

(Equation 25)

It is assumed that Here, ΔT _BH is the set temperature increase in the induction heating device, ΔT _MAX is the maximum temperature increase in the induction heating device, and ΔT _sp is the temperature adjustment by the spray.

Therefore, the spray amount is as follows.

[0103]

(Equation 26)

Here, u _sp : spray amount, u ₀ : spray set amount, K _sp : spray amount feedback gain.

When the output of the induction heating device including the feedback amount is negative or smaller than the minimum output, the power of the induction heating device is set to zero or the minimum set power, and the spray amount is increased.

That is, when ΔT _BH + ΔT _fb <ΔT _MIN ,

[0107]

[Equation 27]

It is assumed that

Thus, the spray amount is as follows.

[0110]

[Equation 28]

Where u _sp : spray amount, u ₀ : spray set amount, and K _sp : spray amount feedback gain. This makes it possible to control the temperature of the entire rough bar 1 so as to match the finishing temperature.

[Fourth Embodiment] FIG. 4 is a diagram showing a basic configuration of a steel sheet rolling apparatus according to a fourth embodiment of the present invention.

As shown in FIG. 4, between the finishing mills 3, a temperature detector 7 for detecting the temperature of the rough bar 1 is provided.

From the target finishing temperature of the rough bar 1, the target temperature at the position of the temperature detector 7 installed between the finishing mills 3 is calculated by using the equations (1) to (12).

Immediately after the leading end of the steel material passes through the temperature detector 7 installed between the finishing mills 3, the temperature detected by the temperature detector 7 and the target temperature assumed on the rough bar 1 are compared. The deviation is calculated, and the output of the induction heating device 2 is fed back. That is,

[0116]

(Equation 29)

The feedback amount is

[0118]

[Equation 30]

Are represented as follows. Here, ΔT _fb : feedback heating amount, T _mr : target temperature, T _mj : detected temperature value,
P _fb : feedback power amount, K _BH : feedback gain.

At this time, if the power amount of the induction heating device including the feedback amount exceeds the capability of the induction heating device, the heating becomes insufficient and the finishing temperature cannot be secured. Therefore, the spray amount is reduced by that amount, and the temperature drop in the finish rolling mill is reduced, so that the temperature on the exit side of the finishing rolling mill is made to coincide with the target temperature.

That is, when ΔT _BH + ΔT _fb > ΔT _MAX ,

[0122]

(Equation 31)

It is assumed that Here, ΔT _BH is the set temperature increase in the induction heating device, ΔT _MAX is the maximum temperature increase in the induction heating device, and ΔT _sp is the temperature adjustment by the spray.

Therefore, the spray amount is as follows.

[0125]

(Equation 32)

Where u _sp : spray amount, u ₀ : spray set amount, and K _sp : spray amount feedback gain.

When the output of the induction heating device including the feedback amount is negative or smaller than the minimum output, the power of the induction heating device is set to zero or the minimum set power, and the spray amount is increased.

That is, when ΔT _BH + ΔT _fb <ΔT _MIN ,

[0129]

[Equation 33]

It is assumed that

Therefore, the spray amount is as follows.

[0132]

(Equation 34)

Here, u _sp : spray amount, u ₀ : spray set amount, and K _sp : spray amount feedback gain. This makes it possible to control the temperature of the entire rough bar 1 so as to match the finishing temperature.

[Fifth Embodiment] FIG. 5 is a diagram showing a basic configuration of a steel sheet rolling apparatus according to a fifth embodiment of the present invention.

As shown in FIG. 5, a temperature detector 8 for detecting the temperature of the coarse bar 1 is provided near the outlet side of the induction heating device 2.

The target temperature at the position of the temperature detector 8 installed on the outlet side of the induction heating device 2 is calculated from the finishing temperature target value of the rough bar 1 by using equations (1) to (12).

Immediately after the tip of the steel material passes through the temperature detector 8 provided on the exit side of the induction heating device 2, the temperature detected by the temperature detector 8 and the target temperature assumed on the rough bar 1 Is calculated, and the output of the induction heating device 2 is fed back. That is,

[0138]

(Equation 35)

The feedback amount is

[0140]

[Equation 36]

Is represented as follows. Here, ΔT _fb : feedback heating amount, T _br : target temperature on the outlet side of the induction heating device, T _bj :
The detected temperature value of the temperature detector on the outlet side of the induction heating device, P _fb : feedback electric energy, _KBH : feedback gain.

At this time, if the power amount of the induction heating device including the feedback amount exceeds the capacity of the induction heating device, the heating becomes insufficient and the finishing temperature cannot be secured. Therefore, the spray amount is reduced by that amount, and the temperature drop in the finish rolling mill is reduced, so that the temperature on the exit side of the finishing rolling mill is made to coincide with the target temperature.

That is, when ΔT _BH + ΔT _fb > ΔT _MAX ,

[0144]

(37)

It is assumed that Here, ΔT _BH is the set temperature increase in the induction heating device, ΔT _MAX is the maximum temperature increase in the induction heating device, and ΔT _sp is the temperature adjustment by the spray.

Thus, the spray amount is as follows.

[0147]

(38)

Here, u _sp : spray amount, u ₀ : spray set amount, and K _sp : spray amount feedback gain.

If the output of the induction heating device including the feedback amount is negative or smaller than the minimum output, the power of the induction heating device is set to zero or the minimum set power, and the spray amount is increased.

That is, when ΔT _BH + ΔT _fb <ΔT _MIN ,

[0151]

[Equation 39]

It is assumed that

Thus, the spray amount is as follows.

[0154]

(Equation 40)

Here, u _sp : spray amount, u ₀ : spray set amount, and K _sp : spray amount feedback gain. Thereby, it is possible to control the temperature of the entire rough bar 1 so as to match the finishing temperature.

[0156]

As described above, according to the present invention, it is possible to provide a steel sheet finishing temperature control method capable of making the finishing temperature of the entire steel sheet match the finishing temperature target value with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a view showing a basic configuration of a steel sheet rolling apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a basic configuration of a steel plate rolling apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a basic configuration of a steel plate rolling apparatus according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a basic configuration of a steel plate rolling apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a basic configuration of a steel plate rolling apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coarse bar, 2 ... Induction heating device, 3 ... Finishing rolling mill group, 4 ... Cooling spray, 5 ... Temperature detector (Induction heating device entrance side), 6 ... Temperature detector (Finishing rolling mill exit side), 7 ... temperature detector (between finishing mills), 8 ... temperature detector (induction heating device exit side).

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Sekine 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Seiji Nakano 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Yoichi Honashiki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4E024 BB07 BB08 BB09 FF10 GG05

Claims (5)

[Claims] 1. A finishing mill for rolling a steel sheet, a heating device installed on the entrance side of the finishing mill, cooling devices installed between the finishing mills and before and after the finishing mill, Using a temperature detector installed on the inlet side of the heating device, in a steel sheet finishing temperature control method of controlling the temperature of the steel sheet to a finishing temperature target value on the finishing rolling mill outlet side, from the finishing temperature target value Calculate a temperature target value at the heating device input side, calculate a deviation between the temperature target value at the heating device input side and a temperature detection value detected by a temperature detector installed at the heating device input side. If the deviation is positive, the steel plate is heated by the heating device, and if the amount of temperature rise exceeds the heating capability of the heating device, the cooling amount of the cooling device is reduced, Is negative, the cooling device Finishing temperature control method of steel plate and controlling so 却量 increase the match finishing temperature of the steel sheet to the finishing temperature target value. 2. A finishing mill for rolling a steel sheet, a heating device installed on the entrance side of the finishing mill, cooling devices installed between the finishing mills and before and after the finishing mill, Using a temperature detector installed on the inlet side of the heating device, in a steel sheet finishing temperature control method of controlling the temperature of the steel sheet to a finishing temperature target value on the finishing rolling mill outlet side, from the finishing temperature target value Calculating a temperature target value at the heating device outlet side; calculating a temperature estimation value at the heating device outlet side from a temperature detection value detected by a temperature detector installed at the heating device inlet side; Calculate the deviation between the temperature target value on the outlet side and the estimated temperature value on the outlet side of the heating device, and when the deviation is positive, raise the temperature of the steel sheet by the heating device, and the amount of this temperature increase When exceeding the heating capacity of the heating device The cooling amount of the cooling device is reduced, and when the deviation is negative, the cooling amount of the cooling device is increased so that the finishing temperature of the steel sheet is controlled to match the finishing temperature target value. Characteristic steel sheet finishing temperature control method. 3. A finishing mill for rolling a steel sheet, a heating device installed on the entrance side of the finishing mill, cooling devices installed between the finishing mills and before and after the finishing mill, Using a temperature detector installed on the exit side of the finishing mill, the method for controlling the finishing temperature of the steel sheet to control the temperature of the steel sheet to a finishing temperature target value on the exit side of the finishing mill, wherein the finishing temperature target value And a deviation between a temperature detection value detected by a temperature detector installed on the exit side of the finishing rolling mill, and when the deviation is positive, the heating device is fed back in a direction in which the amount of temperature rise increases. If the heating amount including the feedback amount exceeds the heating capability of the heating device, the cooling amount of the cooling device is reduced.If the deviation is negative, the heating device is raised. Temperature decrease If the temperature increase including the feedback amount becomes zero or lower than the minimum temperature increase amount, the cooling amount of the cooling device is increased to set the finishing temperature of the steel sheet to the finishing temperature target value. A method for controlling a finishing temperature of a steel sheet, wherein the method is controlled so as to match the temperature. 4. A finishing mill for rolling a steel sheet, a heating device installed on the entrance side of the finishing mill, cooling devices installed between the finishing mills and before and after the finishing mill, Using a temperature detector installed between finishing mills, in a steel sheet finishing temperature control method of controlling the temperature of the steel sheet to a finishing temperature target value at the finish rolling mill exit side, the finishing temperature target value Calculate the deviation between the temperature target value at the temperature detector position calculated from the temperature detection value detected by the temperature detector installed between the finishing rolling mill, if the deviation is positive, the heating The apparatus performs feedback control in a direction in which the amount of temperature increase increases, and when the amount of temperature increase including the amount of feedback exceeds the heating capability of the heating device, the amount of cooling of the cooling device is reduced, and the deviation But In the case of a negative value, feedback control of the heating device is performed in a direction in which the amount of temperature increase is reduced. A method for controlling the finishing temperature of a steel sheet, wherein the finishing temperature of the steel sheet is controlled to be equal to the target value of the finishing temperature by increasing the amount. 5. A finishing mill for rolling a steel sheet, a heating device installed on the entrance side of the finishing mill, cooling devices installed between the finishing mills and before and after the finishing mill, Using a temperature detector installed on the exit side of the heating device, in the method for controlling the finish temperature of the steel sheet to control the temperature of the steel sheet to the finish temperature target value on the finish rolling mill exit side, from the finish temperature target value Calculating a temperature target value at the heating device outlet side, calculating a deviation between the temperature target value and a temperature detection value detected by a temperature detector installed at the heating device outlet side, when the deviation is positive; Performs feedback control of the heating device in a direction in which the heating amount increases, and if the heating amount including the feedback amount exceeds the heating capability of the heating device, decreases the cooling amount of the cooling device. Let said When the difference is negative, the heating device is feedback-controlled in a direction in which the amount of temperature rise is reduced, and when the amount of temperature rise including this feedback amount becomes zero or lower than the minimum amount of temperature rise, the cooling device And controlling the finishing temperature of the steel sheet so as to match the finishing temperature target value by increasing the cooling amount of the steel sheet.