JPH10277627A - Method for controlling outlet temperature of hot rolling mill and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the outlet temperature of a rolling stock precisely within an allowable range by changing the rolling temperature based on the difference between an inlet temperature of the rolling stock measured at an inlet of a hot rolling mill and a target inlet temperature. SOLUTION: The amount of cooling of a hot rolled sheet is obtained from the difference between a target inlet temperature and a target outlet temperature. An initial rolling velocity is set prior to the entrance of a rolling stock into the finishing rolling mill. Based on the set values of the rolling velocity and the amount of cooling, the command of rolling from a velocity controller 9 and the command of the amount of cooling from a temperature controller 10 are sent to the finishing rolling mill to execute rolling. After a prescribed period, an inlet temperature is measured by an inlet side thermometer 6, and a required amount of cooling to the target finishing outlet temperature is calculated, and a new rolling velocity is revisedly set. In the case the finishing temperature is lower than the initial set value, the initial set velocity is raised and rolling time is shortened to decrease the descending amount of air cooling. In the case the finishing temperature is higher than the initial set value, the rolling time is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outlet temperature control method for controlling an outlet temperature of a hot rolling mill and a control device therefor. For example, in a final stage of a hot-rolled steel sheet rolling plant, a plurality of rolling stands are provided. The present invention relates to a finish-rolling-side temperature control for controlling the temperature of a steel sheet after rolling at the finish-rolling mill output side to a preset target temperature in a finish rolling mill that rolls a steel sheet to a predetermined product sheet thickness. .

[0002]

2. Description of the Related Art In order to obtain a good material in hot rolling, it is necessary to keep the finishing temperature within an allowable range from a required target temperature. FIG. 11 shows the configuration of a typical finishing mill in hot rolling. In the drawing, reference numeral 1 denotes a finishing mill comprising N stands, 2
Is an entrance thermometer installed on the entrance side of the finishing mill, and 3 is an exit thermometer installed on the exit side of the finishing mill. Reference numeral 4 denotes a stand-to-stand spray installed between the stands of the finishing mill, which is equipment for cooling the hot-rolled steel sheet 11 by water cooling.

[0003] The hot-rolled steel sheet 11 at the time of entering the finishing mill 1 has a uniform temperature distribution over almost the entire length. By the time the hot-rolled steel sheet 11 passes through the finishing inlet thermometer 2 and enters the finishing mill 1 where it is rolled, and reaches the finishing outlet thermometer 3, the temperature drops mainly by air cooling and the temperature drop by spray water cooling. In addition, there are temperature change phenomena such as a temperature drop due to heat conduction to a roll during rolling, and a temperature rise due to processing heat generated by rolling.

Normally, the leading end of the hot-rolled steel sheet 11 is bitten by a finishing mill at a certain speed, and when all the stands of the finishing mill are in the passing state, the rolling speed is accelerated to the highest possible rolling speed. Change. When the rolling speed changes, the passage time between the finishing mills changes, so that the amount of air cooling temperature drop during this period changes, and as a result, the finishing outlet temperature changes. Also,
The speed is slower on the entrance side of the finishing mill than on the exit side of the finishing mill in which the speed is increased by the thickness reduction by the rolling, and the rolling speed decreases toward the tail end in the longitudinal direction of the hot-rolled steel sheet 11. The waiting time before being bitten by the machine is prolonged, and during this time the steel sheet is cooled by air cooling, and as a result, the finish-side temperature decreases over time. Due to such a temperature change factor, it is complicated to keep the finishing temperature within an allowable range in the longitudinal direction of the steel sheet.

[0005] In the conventional method, for example,
Japanese Patent Application Laid-Open No. 58-181407 discloses a method in which the passing time between finishing mills is changed by changing the rolling speed, and the finishing temperature is adjusted by changing the air cooling temperature drop. In the publication, there is a method in which the number of strip coolants by the inter-stand spray is changed to change the water cooling temperature drop amount to adjust the finishing side temperature.

In the conventional method of controlling the finish-side temperature, the rolling speed and the spray between stands are determined by the time the hot-rolled steel sheet reaches the finish-rolling mill from the finish-side temperature to the required finish-side target temperature. Rolling speed and stand-to-stand spraying using the air cooling temperature drop calculation formula and water cooling temperature drop calculation formula based on heat transfer theory, etc. based on the cooling temperature drop required to reach Determine the amount.

Then, the hot rolled steel sheet is rolled by a finishing mill at the end of the hot rolled steel sheet at the determined rolling speed and spray water amount. Next, from the start of rolling, from the actual finish-side temperature measured by the finish-side thermometer installed on the finish-rolling mill output side, see the deviation from the finish-side target temperature, the deviation In order to reduce the size, a method of adjusting the rolling speed or the amount of spray water between stands dynamically is adopted.

[0008]

According to the conventional control method, the finish-side temperature of the hot-rolled steel sheet is dynamically controlled in accordance with the level of the deviation between the actual finish-side temperature value and the target temperature. The mainstream method was to change the rolling speed and the amount of spray water stepwise. However, with this method, the amount of cooling can be controlled only stepwise, so that it is not possible to obtain an appropriate rolling rate or a change in the amount of spray water according to the magnitude of the temperature deviation on the finishing side. There was a problem that the good control could not be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to satisfy the temperature of a steel sheet after rolling at the exit side of a finishing rolling mill within an allowable range from a predetermined required target temperature. It is an object of the present invention to provide an optimum finishing-side temperature control method for achieving the following.

[0010]

[Means for Solving the Problems]

(1) An outlet temperature control method for a hot rolling mill according to the present invention is a method for controlling an outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands. The rolling speed is changed according to the difference between the entrance temperature of the rolled material and the target entrance temperature to control the exit temperature of the rolled material within an allowable range.

(2) In the outlet temperature control method for a hot rolling mill according to the above (1), the outlet temperature of the rolled material is compared with a target outlet temperature, and the next rolling is performed according to the comparison result. The rolling speed of the material is modified.

(3) In a method for controlling the outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, the inlet temperature of a rolled material and the target inlet side are controlled. The amount of cooling by the spray is changed according to the difference from the temperature to control the outlet temperature of the rolled material within an allowable range.

(4) In the outlet temperature control method for a hot rolling mill according to the above (3), the outlet temperature of the rolled material is compared with a target outlet temperature, and the next rolling is performed according to the comparison result. The amount of cooling by the spray for discharging the cooling water of the material is modified.

(5) In the method for controlling the outlet temperature of a hot rolling mill according to any one of the above (1) to (4), the inlet temperature is a temperature between the rolling stands close to the inlet. It is a temperature.

(6) In the method for controlling the outlet side temperature of a hot rolling mill according to any one of the above (1) to (5), the control based on the change in the rolling speed or the control based on the change in the cooling amount by spraying is performed by: The process is executed when the entrance temperature of the rolled material is out of a predetermined allowable range.

(7) In the method for controlling the outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, a method of controlling a rolling speed with respect to an amount of change in the outlet temperature in advance. The amount of change in the acceleration rate is determined as a first influence coefficient, and according to the required amount of change in the acceleration rate obtained by multiplying the deviation between the exit temperature of the rolled material and the target exit temperature by the first influence coefficient. The rolling speed is changed to control the outlet temperature within an allowable range.

(8) In the outlet temperature control method for a hot rolling mill according to the above (7), the rolling speed is changed by changing the rolling speed in accordance with the result of multiplying the required acceleration rate change amount by a predetermined tuning rate. The outlet temperature of the material is controlled within an allowable range, and the tuning rate is adjusted according to the actual accuracy of the outlet temperature by this control.

(9) In the outlet temperature control method for a hot rolling mill having a spray for discharge, the amount of change in the amount of spray water with respect to the amount of change in the outlet temperature is determined in advance as a second influence coefficient. The spray water amount is changed in accordance with a required water amount change amount obtained by multiplying a deviation between the outlet temperature of the target and the target outlet temperature and the second influence coefficient so as to control the outlet temperature within an allowable range. It was done.

(10) In the outlet temperature control method for a hot rolling mill according to the above (9), the amount of spray water is changed in accordance with the result of multiplying the required amount of water change by a predetermined tuning rate, and the rolled material is changed. Is controlled within an allowable range, and the tuning ratio is adjusted in accordance with the actual accuracy of the output temperature by this control.

(11) The above (9) or (10)
The control by the step change of the spray cooling amount is performed by the outlet temperature control method of the hot rolling mill, and the control between the respective steps is controlled by the outlet temperature control of the hot rolling mill according to the above (7) or (8). The rolling speed is changed and controlled according to the method.

(12) If the outlet temperature of the rolled material is higher than the target outlet temperature, or if the outlet temperature exceeds a predetermined upper limit of the allowable range, the above (9) or (1)
Control is performed by changing the spray cooling amount using the outlet temperature control method of the hot rolling mill of 0), and when the outlet temperature of the rolled material is lower than the target outlet temperature, or when the outlet temperature is lower than the target outlet temperature. When the temperature is lower than the lower limit of the predetermined allowable range, the control is performed by changing the rolling speed using the outlet temperature control method of the hot rolling mill described in (7) or (8).

(13) An output temperature control device for a hot rolling mill using the output temperature control method for a hot rolling mill described in (1) to (12).

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention will be described. FIG. 1 is a diagram illustrating a control mode according to the first embodiment, and is a configuration diagram of a finishing mill. In the drawing, reference numeral 5 denotes a finishing outlet thermometer on the exit side of the finishing mill final stand, 6 denotes a finishing inlet thermometer on the inlet side of the finishing mill first stand, and 7 denotes a finishing rolling mill final stand.

Reference numeral 8 denotes a stand-to-stand spray provided between the rolling stands for cooling the hot-rolled steel sheet 11, and this spray can be individually controlled separately, and the spray is turned on / off. Because it can only be done, very fine control is not possible. Reference numeral 9 denotes a speed controller, which is a control device for controlling the rolling speed of the finishing mill.
Is a temperature controller, which is a control device for controlling spray between cooling stands provided in the finishing mill.

According to the conventional method, a target finishing temperature (hereinafter abbreviated as FDT) is predicted while observing the rolling conditions, and an initial set rolling speed and an initial spray cooling amount are determined. Control while changing the rolling speed, acceleration pattern, and spray cooling amount so that it reaches the target finish output temperature. Did not go.

In the first embodiment, the target finishing temperature (hereinafter abbreviated as FET) is measured at a certain fixed period, and the rolling speed setting is corrected on the finishing side to obtain a higher value than the conventional control method. It is intended to control the accuracy.

Hereinafter, a specific control method will be described.
FIG. 2 is a flowchart of a main part of a control method for one control cycle in this embodiment. (1) The difference between the FET (the target finish-side temperature) and the FDT (the target finish-side temperature) is the sum of the amount of air-cooled drop cooled by outside air and the amount of water-cooled drop cooled by water. That is, FET-FDT = TAIR (V) + TW (V) --- (1.1) where, TAIR (V) is the amount of air cooling drop, and TW (V) is the amount of water cooling drop. Find the quantity.

(2) The initial rolling speed is set by the equation (1.1) before the rolled material enters the finishing mill. (3) The rolling speed command value from the speed controller 5 based on the speed setting / cooling amount setting and the temperature controller 1
From 0, the command value of the cooling amount is sent to the finishing mill, and the rolling is performed.

(4) Thereafter, after a certain period, the finishing-side temperature is measured again (S1), and (5) the required cooling amount to the target FDT is calculated by the equation (1.1) (S2). (6) The rolling speed is recalculated by replacing the numerical value of the FET (S3). (7) The rolling speed is reset and corrected (S4).

That is, if the finishing inlet temperature is lower than at the time of the initial setting, the initial setting speed is increased, the rolling time in the finishing mill is shortened, and the amount of air-cooled drop of the rolled material, that is,
Reduce TAIR (V). On the other hand, if the finishing temperature is higher than the initial setting, lower the initial setting speed,
The rolling time in the finishing mill is lengthened, and the amount of air-cooled fall of the rolled material is increased.

If the cycle for performing this control is shortened, the finishing temperature is measured in a shorter cycle than in the conventional control, and the measured temperature is reflected in the control. Control can be performed, and the finishing temperature can be accurately controlled.

The control cycle depends on the processing capability of the control device, but substantially continuous control is performed by improving the performance of the microprocessor. For example, the control is performed in a short cycle of about 100 msec.

As described above, conventionally, the rolling speed set when the hot-rolled steel sheet bites into each stand sequentially from the finish rolling mill entry side and the initial value of the spray water amount between the stands are hot rolling. It is calculated and determined for the tip of the steel plate,
After that, in the first embodiment of the present invention, a correction resetting calculation is performed based on the actual temperature at the finishing entrance side of the hot-rolled steel sheet sequentially collected at the entrance side of the finishing mill. By controlling the rolling speed by correcting the rolling speed, it is possible to perform dynamic control in consideration of fluctuations in the finishing-side temperature, and to control the finishing-side temperature with high accuracy.

Further, as a modified example of the above embodiment, when the finishing inlet side temperature is out of a predetermined allowable range, the above-described recalculation may be performed and controlled.

Embodiment 2 Next, a second embodiment will be described. In this embodiment, in addition to the first embodiment, the ratio of the actual FDT obtained from the front end to the tail end of the rolled material after rolling and the target FDT is used as a learning coefficient, and is used as a setting for each acceleration region of the rolling speed. It is multiplied as a coefficient of the rolling speed.

Hereinafter, the second embodiment will be described with reference to FIG. FIG. 3A shows a typical speed change of a rolled material in a finish rolling mill. The horizontal axis indicates time T, and the vertical axis indicates speed V. The shorter time is the speed on the leading end side of the rolled material, and the longer time is the tail end speed of the rolled material. As shown in this drawing, the speed is in a steady state for a while after being engaged with the first stand of the finishing mill. Thereafter, there is a portion where the rolled material accelerates, which is called a first acceleration region. After that, there is a portion to be newly accelerated, which is called a second acceleration region.

FIG. 3B shows a change in FDT from the leading end to the tail end of the rolled material at that time. Here, the ratio between the actual FDT and the target FDT in each speed range, that is, the learning coefficient μ is obtained. Then, a certain number of learning coefficients are measured in each of the three speed regions, and the average is used as the learning coefficient of the speed region.

That is, μ _I = 1 + (ΔFDT / FDT ₀ )-(2.1) ΔFDT = FDT-FDT ₀ ----- (2.2)

[0039]

(Equation 1)

However, K = 1, 2, 3 K is the speed region No. Learning coefficient at the FDT actual FDT FDT ₀ goals FDT mu _I learning coefficient mu ₀ ^K speed region K

The learning method will be described below. (1) The initial setting method and the control method are the same as those in the first embodiment. (2) M learning points are set in advance at predetermined intervals (at predetermined time intervals) of learning coefficient extraction points in each speed region.

(3) Then, after rolling, the actual FDT and the target FDT at the I-th learning point in the first acceleration region of the material of a certain layer (material discrimination based on the material, width, and thickness of the steel sheet) A in the first acceleration region from ₀ to determine the learning coefficient mu _I from equation (2.1). That is, the I-th actual FDT of the material in the first acceleration region is higher (or lower) than the target FDT by (μ _I −1) · FDT ₀ (= ΔFDT).

(4) This learning coefficient is integrated at M learning coefficient extraction points provided in the first acceleration region, and the equation (2.
An average learning coefficient is obtained as in 3). (5) Then, by using the learning coefficient of each layer and the number N of the materials of the layer A which have been stored so far in the file for each layer and each acceleration area, a new layer is newly added. The learning coefficient μ _X and the number N _A of lines flowing up to this time are calculated by the following equations.

Μ _X = (μ _A · N + μ ₀ ¹ ) / (N + 1) −−−− (2.4) N _A = N + 1 −−−− (2.5)

(6) Next, when rolling a material having the same stratified number, a value obtained by multiplying the target FDT by the learning coefficient μ _X is used as a new target FDT when performing a setting calculation. That is, the target FDT FDT _1, when the target FDT and FDT _X used for setting calculation, the _{FDT X = μ X · FDT 1} ----- (2.6).

(7) The target FDT used for the setting calculation (for each control target point of the rolled material) is calculated every time using the expression (2.6), and the passing speed is changed using the target FDT. Go. This control method is also applied to other speed regions such as the steady state and the second acceleration region, and performs the same control method.

By performing control using the control method taking into account the learning effect as described above, the accuracy of calculating the amount of cooling from the FET to the FDT is improved, and more accurate finishing-side temperature control can be performed.

Embodiment 3 Next, a third embodiment will be described. In the first embodiment, the rolling speed setting is recalculated and corrected on the finishing side while watching the FET at regular intervals while watching the rolling conditions, thereby realizing high-precision control.

In this case, however, the fact that the rolling speed changes dynamically due to the fluctuation of the FETs taken at regular intervals may make the operation unstable and may not lead to a stable operation. Therefore, the third embodiment is a control for securing the target FDT by changing the cooling amount of the inter-stand spray provided between the rolling stands for cooling the hot-rolled steel sheet without changing the rolling speed or the acceleration rate thereof. .

The specific control will be described below. FIG.
3 is a flowchart of a main part of a control method for a certain control cycle. (1) The initial rolling speed and acceleration pattern are set before the rolled material enters the finishing mill. (2) The speed setting of (1) and the formula (1.
The cooling amount is set according to 1), and based on the speed setting and the cooling amount setting, a passing speed command value from the speed controller 9 and a cooling value command value from the temperature controller 10 are sent to the finishing mill, and rolling is performed. Done.

(3) Thereafter, after a certain period, the finishing-side temperature is measured again (T1), and (4) the required cooling amount to the target FDT is calculated in the above-mentioned equation (1.1) ( T2), (5) Replace the numerical value of the FET and recalculate the cooling amount again (T3), (6) Reset and correct the spray cooling amount (T4).

That is, if the temperature on the finishing side is lower than that at the time of the initial setting, the cooling amount is reduced and the setting is corrected, while the temperature on the finishing side is higher than at the time of the initial setting. If so, the setting is corrected by increasing the current cooling amount.

If the cycle of performing this control is shortened, the finish-out side temperature control can be performed in a stable operation state as compared with the first embodiment, and the finish-in side temperature control can be performed in a shorter cycle than the conventional control. By measuring the temperature and reflecting it in the control, the finishing temperature can be controlled with high accuracy.

Embodiment 4 Next, a fourth embodiment will be described. This embodiment is different from the third embodiment in that
After rolling, the FD sampled from the tip to the tail end of the rolled material
The ratio of the actual T to the target FDT is used as a learning coefficient, and the learning coefficient is multiplied by the newly set cooling amount as a coefficient.

That is, in the case where the rolling speed is controlled by changing the rolling speed in the first embodiment, the rolling speed is corrected by learning according to the second embodiment. The result based on the cooling amount is learned and corrected. Therefore, the learning method is performed in the same manner as in the second embodiment.

The fourth embodiment will be described with reference to FIG. 3 used in the second embodiment. FIG. 3A shows a change in speed of a rolled material in a finishing mill. The horizontal axis indicates time T, and the vertical axis indicates speed V. The shorter time is the speed on the leading end side of the rolled material, and the longer time is the tail end speed of the rolled material. As shown in this drawing, the speed is in a steady state for a while after being engaged with the first stand of the finishing mill. Thereafter, there is a portion where the rolled material accelerates, which is called a first acceleration region. After that, there is a portion to be newly accelerated, which is called a second acceleration region.

FIG. 3B shows the change in FDT from the leading end to the tail end of the rolled material at that time. Here, the ratio between the actual FDT and the target FDT in each speed range, that is, the learning coefficient μ is obtained. Then, a certain number of learning coefficients are measured in each of the three speed regions, and the average is used as the learning coefficient of the speed region.

That is, μ _I = 1 + (ΔFDT / FDT ₀ )-(4.1) ΔFDT = FDT-FDT ₀ ----- (4.2)

[0059]

(Equation 2)

However, K = 1, 2, 3 K is the speed region No. Learning coefficient at the FDT actual FDT FDT ₀ goals FDT mu _I learning coefficient mu ₀ ^K speed region K

The equations (4.1), (4.2), (4.
3) is the same as equations (2.1), (2.2), and (2.3).

The learning method will be described below. (1) The initial setting method and control method are the same as those in the third embodiment. (2) M learning points are set in advance at predetermined intervals (at predetermined time intervals) of learning coefficient extraction points in each speed region.

(3) After rolling, the result F at the I-th learning point in the first acceleration region of the material of a certain layer A is obtained.
From the DT and the target FDT ₀ , the learning coefficient μ is obtained from Expression (4.1)
_Ask for _I. That is, the material I in the first acceleration region
The second actual FDT is higher (or lower) than the target FDT by (μ _I −1) · FDT ₀ (= ΔFDT).

(4) The learning coefficients are integrated at M learning coefficient extraction points provided in the first acceleration region, and the equation (4.
An average learning coefficient is obtained as in 3). (5) Then, by using the learning coefficient of each layer and the number N of the materials of the layer A which have been stored so far in the file for each layer and each acceleration area, a new layer is newly added. The learning coefficient μ _X and the number N _A of lines flowing up to this time are calculated by the following equations.

Μ _X = (μ _A · N + μ ₀ ¹ ) / (N + 1) −−−− (4.4) N _A = N + 1 −−−− (4.5)

[0066] (6) Next, when rolling the same stratification number of materials, the value obtained by multiplying the learning coefficient mu _X to the target FDT as a new target for FDT, used when the setting calculation. That is, the target FDT FDT _1, when the target FDT and FDT _X used for setting calculation, the _{FDT X = μ X · FDT 1} ----- (4.6). Equations (4.4), (4.5), (4.6)
Is the same as the expressions (2.4), (2.5), and (2.6).

(7) The target FDT used for the setting calculation (for each control target point of the rolled material) is calculated each time using the expression (4.6), and the cooling amount is changed using the target FDT. . This control method is also applied to other speed regions such as the steady state and the second acceleration region, and performs the same control method.

When the control is performed by the control method as described above, the accuracy of the calculation of the cooling amount from the FET to the FDT is improved by adding learning, and more accurate finishing-side temperature control can be performed.

Embodiment 5 Next, a fifth embodiment will be described. In the first embodiment, the finishing inlet temperature (hereinafter abbreviated as FET) is measured at certain fixed intervals, the rolling speed setting is corrected and recalculated on the finishing inlet side, and control with higher accuracy than the conventional control method is performed. It was going to be.

However, the FET measured by the finishing thermometer of the actual rolling plant is exposed to the outside air until the hot-rolled steel sheet reaches the finishing thermometer, and is affected by the scale on the rolled material. A sufficiently reliable FET cannot be measured. If this finishing inlet thermometer is installed downstream of the scale breaker installed on the finishing inlet side, the scale is not mounted on the rolled material, and accurate FET measurement can be performed.

Therefore, in the fifth embodiment, the finishing inlet thermometer installed on the finishing inlet is installed immediately after the finishing first stand, and the FET measured therefrom is used to perform rolling on the finishing inlet. The speed setting is corrected and re-calculated to realize a control with higher precision than in the first embodiment.

FIG. 5 is a configuration diagram of a finishing mill facility in this embodiment. Here, the finishing inlet thermometer 6 is the first
It is installed immediately after the stand, and controls the actual temperature sampled by the thermometer 6 as the finishing temperature. The specific calculation control method is the same as in the first embodiment.

When control is performed by the control method as described above, it is possible to measure FETs with higher reliability than in the first embodiment, and as a result, it is possible to perform finishing temperature control with improved control accuracy. It can be carried out.

Embodiment 6 FIG. Next, a sixth embodiment will be described. In the sixth embodiment, the finishing inlet thermometer installed on the entrance side of the finishing mill is installed immediately after the finishing first stand, and the rolling speed setting on the finishing inlet side is performed by using the FET measured therefrom. Is corrected and recalculated to realize high-precision control, and after rolling, the ratio between the actual FDT obtained from the front end to the tail end of the rolled material and the target FDT is used as a learning coefficient, which is set for each acceleration region. It is multiplied as a coefficient of the rolling speed. A specific calculation control method is described in Embodiment 2.
Is the same as

When control is performed by the control method as described above, it becomes possible to measure FETs with higher reliability than in the fifth embodiment, and by adding a learning function, a high-precision finish can be obtained. Side temperature control can be performed.

Embodiment 7 Next, a seventh embodiment will be described. In the third embodiment, the finishing-side temperature (hereinafter abbreviated as FET) is measured at certain fixed intervals, and the cooling amount of the inter-stand spray provided between the rolling stands for cooling the hot-rolled steel sheet is changed to achieve the target. Control to secure the FDT to be performed.

However, as described above, the FET measured by the finishing thermometer of the actual rolling plant is exposed to the outside air until the hot-rolled steel sheet reaches the finishing thermometer. A sufficiently reliable FET cannot be measured due to the influence of the scale. If this finishing inlet thermometer is installed downstream of the scale breaker installed on the finishing inlet side, the scale is not mounted on the rolled material, and accurate FET measurement can be performed.

Therefore, in the seventh embodiment, the finishing inlet thermometer installed on the finishing inlet is installed immediately after the first finishing stand, and the FET measured therefrom is used to cool the hot-rolled steel sheet. In this embodiment, the amount of cooling of the inter-stand spray provided between the rolling stands is changed to realize more accurate control than in the third embodiment. The specific calculation control method is the same as in the third embodiment.

When control is performed by the control method as described above, it is possible to measure FETs with higher reliability than in the third embodiment, and as a result, it is possible to perform finishing temperature control with improved control accuracy. It can be carried out.

Embodiment 8 FIG. Next, an eighth embodiment will be described. In the eighth embodiment, the finishing inlet thermometer installed on the finishing inlet is installed immediately after the first finishing stand, and the FET measured from there is used to cool the spray between stands on the finishing inlet. The amount is corrected and recalculated, high-precision control is realized, and after rolling, the ratio between the actual FDT obtained from the front end to the tail end of the rolled material and the target FDT is set as a learning coefficient, and is newly set. The cooling amount is multiplied as a coefficient. The specific calculation control method is the same as in the fourth embodiment.

When control is performed by the control method as described above, it is possible to measure FETs with higher reliability than in the seventh embodiment, and by adding a learning function, it is possible to obtain a highly accurate finish. Side temperature control can be performed.

Embodiment 9 FIG. In Embodiments 1 to 8,
The embodiment of the feedforward control for controlling the rolling speed and the amount of spray water between stands from the actual value of the finishing inlet temperature (FET) has been described. Next, the actual value of the finishing outlet temperature (hereinafter referred to as FDT) will be described. An embodiment of feedback control for controlling the rolling speed will be described.

In this embodiment, conventionally, when the FDT deviates from the target FDT and a deviation occurs, the magnitude of the deviation amount is divided into several steps, and the acceleration rate is stepwisely adjusted according to each step. The control accuracy is made finer by continuously changing the changed one using the influence coefficient.

FIG. 6 is a flowchart for explaining this control method. Hereinafter, this embodiment will be described. (1) First, influence coefficient of change rate of required acceleration rate a to FDT deviation

[0085]

(Equation 3)

Is calculated in advance (U1). As a method of obtaining the influence coefficient, there are two formulas for calculating a temperature drop when passing through a finishing mill and a formula for calculating a temperature drop due to air cooling on the finishing side, and calculating a finish-out side temperature. From the equation, it can be obtained by partial differential calculation.

(2) Next, the actual performance of the FDT during the rolling acceleration is measured (U2), and (3) the deviation ΔFDT from the target FDT is calculated (U2).
3), (4) When the deviation ΔFDT occurs, the following equation (9.1) is used.
(U4), the change rate Δa of the appropriate acceleration rate a according to the amount of ΔFDT is obtained.

[0088]

(Equation 4)

(5) As shown in equation (9.2), the rolling speed is controlled so that the corrected acceleration rate a 'is obtained by adding the above-mentioned Δa to the current acceleration rate a (U5). a ′ = a + Δa −−−−−−−−−−−−− (9.2) (6) The calculation processing of (9.1) and (9.2) was repeated for each control cycle. Perform feedback control.

As described above, by performing the feedback control, even if the FDT deviation continuously changes, an appropriate acceleration rate variation ΔA corresponding to the magnitude of the deviation ΔFDT is obtained.
a can be obtained, and the finishing temperature control with improved control accuracy can be realized.

Embodiment 10 FIG. In the ninth embodiment,
Pre-calculated influence coefficient

[0092]

(Equation 5)

The method of controlling the rolling speed by calculating the appropriate change rate Δa of the acceleration rate a using the above-described method for each control cycle has been described. Where the influence coefficient

[0094]

(Equation 6)

Is constant and has the same value in each control cycle. Therefore, if the influence coefficient

[0096]

(Equation 7)

If an error occurs between the predicted calculated value and the actual value, the calculated value of the corrected acceleration rate using the influence coefficient of the predicted calculated value also includes an error. It will come off.

Therefore, in the formula for calculating the corrected acceleration rate, F is multiplied by the tuning rate in addition to the influence coefficient.
An example in which the control accuracy is improved by automatically adjusting the tuning rate in accordance with the performance of the DT control accuracy is considered.

FIG. 7 explains the flow of operation of this embodiment. Note that V1 to V1 in this flowchart
V5 is the same as U1 to U5 in FIG. 6 of the ninth embodiment, and therefore the description will focus on the differences.

(1) The calculation formula of the change rate Δa of the acceleration rate a expressed by the formula (9.1) of the ninth embodiment is as follows:
0.1) (V1).

[0101]

(Equation 8)

Here, α is a tuning rate, and α =
When 1.0, influence coefficient

[0103]

(Equation 9)

Corresponds to the fact that has not been corrected.

(2) First, the initial value of the tuning rate is set to 1.0, and control is performed on one rolled steel sheet at the initial value of the tuning rate. (3) At the same time as performing the control, the actual finisher temperature is also collected (V2). (4) When the control of the entire rolled steel sheet is completed (V2
ＶV5), (5) The finishing temperature accuracy is calculated from the actual temperature of the rolled steel sheet (for example, a standard deviation value from the finishing temperature target temperature over the entire length of the steel sheet) (V6).

(6) Next, the tuning ratio is adjusted based on the finishing temperature accuracy (V7). If the temperature accuracy on the finishing side deteriorates, the tuning rate is lowered and used for controlling the next rolled steel sheet. Conversely, when the temperature accuracy on the finishing side is improved, the tuning rate is increased and used for controlling the next rolled steel sheet.

By automatically adjusting the tuning ratio in this manner, control can always be performed with the optimum tuning ratio.

Embodiment 11 FIG. In the ninth embodiment,
Although the feedback control for changing the rolling speed in accordance with the FDT deviation has been described, this may be a method of changing the spray water amount between stands according to the FDT deviation.

FIG. 8 illustrates this control method. Hereinafter, this embodiment will be described. (1) First, the influence coefficient of the change rate of the required stand-to-stand spray water amount Q to the FDT deviation

[0110]

(Equation 10)

Is calculated in advance (W1). As a method of obtaining the influence coefficient, it can be obtained by a partial differential calculation from a calculation formula for calculating a temperature drop due to spray water cooling between stands when passing through a finishing mill.

(2) Next, the actual performance of the FDT during the rolling acceleration is measured (W2), and (3) the deviation ΔFDT from the target FDT is calculated (W2).
3), (4) When a deviation ΔFDT from the target FDT occurs, an appropriate change rate ΔQ of the inter-stand spray water amount Q according to the amount of ΔFDT is obtained according to the following equation (11.1) (W
4).

[0113]

[Equation 11]

(5) As shown in the equation (11.2), the spray water amount is controlled so as to be a corrected water amount Q ′ obtained by adding ΔQ obtained above to the current inter-stand spray water amount Q. Q ′ = Q + ΔQ …………………………… (11.2)

(6) The feedback control in which the calculation processing of (11.1) and (11.2) is repeated every control cycle is performed.

By performing the above-described feedback control, even if the FDT deviation continuously changes, it is possible to obtain an appropriate inter-stand spray water amount variation ΔQ in accordance with the magnitude of the variation ΔFDT. Finishing-side temperature control with improved control accuracy can be realized.

Embodiment 12 FIG. In the eleventh embodiment, the influence coefficient calculated in advance

[0118]

(Equation 12)

Appropriate inter-stand spray water volume Q using
The method of controlling the rolling speed by calculating the rate of change ΔQ for each control cycle has been described.

Here, the influence coefficient

[0121]

(Equation 13)

Is constant and has the same value in each control cycle.

Therefore, if the influence coefficient

[0124]

[Equation 14]

If an error occurs between the predicted calculated value and the actual value, the calculated value of the corrected acceleration rate using the influence coefficient of the predicted calculated value also includes an error. It will come off.

Therefore, in the formula for calculating the corrected spray water amount, an example in which the control accuracy is increased by automatically adjusting the tuning ratio in accordance with the actual performance of the FDT control accuracy as a form in which the tuning ratio is multiplied in addition to the influence coefficient. Can be considered.

FIG. 9 illustrates this embodiment. It should be noted that X1 to X5 in this flowchart are the same as W1 to W5 in FIG.

(1) In the eleventh embodiment, (11.1)
A calculation formula of the change rate ΔQ of the spray water amount Q expressed by the formula is set as the following formula (12.1).

[0129]

(Equation 15)

Here, α is a tuning rate, and α =
When 1.0, influence coefficient

[0131]

(Equation 16)

(X)
1).

(2) First, the initial value of the tuning rate is set to 1.0, and control is performed on one rolled steel sheet at the initial value of the tuning rate. (3) At the same time as performing the control, the actual finisher temperature is also collected (X2). (4) When the control of the entire rolled steel sheet is completed (X2
ＸX5), (5) The finishing temperature accuracy is calculated from the actual temperature of the rolled steel sheet (for example, a standard deviation value from the finishing output target temperature over the entire length of the steel sheet) (X6).

(5) Next, the tuning rate is adjusted based on the temperature accuracy on the finishing side (X7). If the temperature accuracy on the finishing side deteriorates, the tuning rate is lowered and used for controlling the next rolled steel sheet. Conversely, when the temperature accuracy on the finishing side is improved, the tuning rate is increased and used for controlling the next rolled steel sheet.

By automatically adjusting the tuning ratio in this manner, control can always be performed with the optimum tuning ratio.

Embodiment 13 FIG. In the ninth to twelfth embodiments, the feedback control for controlling either the rolling speed or the amount of spray water between stands based on the deviation of the actual temperature on the finishing side has been described. Can be in control.

First, in the control method based on the change in the amount of spray water between stands, the effect of temperature cooling is greater in water cooling than in air cooling. In general, it is possible to change the amount of water by switching on and off the spray. In this case, the amount of water can be adjusted only discretely, and therefore, the amount of water cooling temperature drop can only be discretely controlled stepwise.

On the other hand, in the control method by changing the rolling speed,
The rolling speed can be changed continuously and continuous control is possible.

(1) First, the influence coefficient of the change rate of the required acceleration rate a on the FDT deviation

[0140]

[Equation 17]

Influence coefficient of change rate of required stand-to-stand spray water amount Q to FDT deviation

[0142]

(Equation 18)

Are calculated in advance.

(2) Next, when a deviation ΔFDT occurs in the FDT during rolling acceleration, an appropriate change rate ΔQ of the inter-stand spray water amount Q according to the amount of ΔFDT is obtained according to the following equation (13.1). .

[0145]

[Equation 19]

(3) As shown in the equation (13.2), the on / off pattern closest to the corrected water amount Q ′ obtained by adding ΔQ obtained above to the water amount Q in the current inter-stand spray on / off pattern is determined. Q ′ = Q + ΔQ ……………………………… (13.2)

(4) The FDT correction amount obtained by changing the above-mentioned uncorrected spray-on / off pattern to the corrected on-off pattern is defined as ΔFDT ′. Correction amount ΔFD that cannot be corrected by changes
T ″ is calculated by the following equation (13.3). ΔFDT ″ = ΔFDT−ΔFDT ′ (13.3)

(5) Next, the change rate Δa of the acceleration rate a required to correct the correction amount ΔFDT ″ is obtained from the following formula (13.4).

[0149]

(Equation 20)

(6) Control is performed based on the spray-on / off correction pattern obtained as described above and the correction acceleration rate.

In this way, fine control can be performed by selectively using the control such that the change in the rolling speed is added to the change in the spray water amount in a corrective manner.

Embodiment 14 FIG. In this embodiment, a description will be given of finishing temperature control by using both the stand-to-stand spray control and the rolling speed control so that the productivity of the hot-rolled steel sheet is as high as possible.

FIG. 10 illustrates this control method. (1) First, the finish-rolling delivery side temperature is measured, and this is set as the actual finish delivery side temperature. (2) When the actual finish output temperature is lower than the lower tolerance limit of the target finish output temperature, the acceleration rate is increased by the rolling speed changing method according to the ninth to tenth embodiments.
The finishing temperature is increased to the target finishing temperature.

(3) On the other hand, when the actual finish output temperature becomes higher than the upper limit of the tolerance of the target finish temperature, the water amount is increased by the water amount changing method according to Embodiments 11 to 12 to increase the finish output side temperature. Reduce the temperature to the target finish output temperature.

As described above, the method of controlling the target finish-side temperature during the rolling acceleration is to increase the acceleration rate when the temperature decreases, and to increase the spray water amount when the temperature increases, as described above. By using such a combination method, it is possible to minimize the time required to reach the maximum speed without reducing the acceleration rate, and to perform control giving priority to productivity.

Embodiment 15 FIG. Embodiments 1 to 14 above
In the above, the method of controlling the finishing temperature has been described, but a finishing temperature control device to which these methods are applied can be configured.

[0157]

【The invention's effect】

(1) As described above, according to the present invention, the feed-forward control is performed by changing the rolling speed or the spray cooling amount according to the deviation between the actual inlet temperature and the target inlet temperature. Temperature can be controlled accurately.

(2) The feedback control is performed by changing the rolling speed and / or the amount of spray water in accordance with the result of multiplication of the deviation of the outlet temperature and the influence coefficient, so that the outlet temperature is accurately controlled. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a finish rolling mill facility according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart of a control method according to the first embodiment of the present invention.

FIG. 3 is a view showing a second embodiment and a third embodiment of the present invention;
FIG. 4 is a diagram showing a change in the speed of the rolled material of the finish rolling mill and a change in the finish delivery side temperature in FIG.

FIG. 4 is a flowchart of a control method according to Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram of finishing mill equipment according to Embodiment 3 of the present invention.

FIG. 6 is a flowchart of a control method according to Embodiment 9 of the present invention.

FIG. 7 is a flowchart of a control method according to Embodiment 10 of the present invention.

FIG. 8 is a flowchart of a control method according to Embodiment 11 of the present invention.

FIG. 9 is a flowchart of a control method according to Embodiment 12 of the present invention.

FIG. 10 is an explanatory diagram showing a control method according to Embodiment 14 of the present invention.

FIG. 11 is a configuration diagram of a finish rolling mill in conventional hot rolling.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Finish rolling mill 2 Finishing thermometer 3 Finishing thermometer 4 Spray between stands 5 Finishing thermometer 6 Finishing thermometer 7 Finishing final stand 8 Stand spray 9 Speed controller 10 Temperature controller 11 Hot rolled steel sheet

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenichiro Sasamoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (13)

[Claims] 1. A method for controlling an outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, comprising: An outlet temperature control method for a hot rolling mill, wherein a rolling speed is changed according to a difference to control an outlet temperature of the rolled material within an allowable range. 2. The outlet temperature control method for a hot rolling mill according to claim 1, wherein the outlet temperature of the rolled material is compared with a target outlet temperature, and the next rolled material is controlled in accordance with the comparison result. A method for controlling an outlet temperature of a hot rolling mill in which a rolling speed is corrected. 3. A method for controlling an outlet side temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, comprising: An outlet temperature control method for a hot rolling mill, wherein an amount of cooling by the spray is changed according to a difference to control an outlet temperature of the rolled material within an allowable range. 4. The outlet temperature control method for a hot rolling mill according to claim 3, wherein the outlet temperature of the rolled material is compared with a target outlet temperature, and the next rolled material is controlled in accordance with the comparison result. An outlet temperature control method for a hot rolling mill in which the amount of cooling by spraying cooling water is corrected. 5. The outlet side temperature control method for a hot rolling mill according to claim 1, wherein the inlet side temperature is a temperature between the rolling stands near the inlet side. A method for controlling the outlet temperature of a hot rolling mill. 6. The method for controlling the outlet temperature of a hot rolling mill according to claim 1, wherein the control by changing the rolling speed or the control by changing the cooling amount by spraying is performed.
An outlet-side temperature control method for a hot rolling mill, which is executed when an inlet-side temperature of a rolled material is out of a predetermined allowable range. 7. A method for controlling an outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, wherein a change in an acceleration rate of a rolling speed with respect to a change amount of an outlet temperature in advance. The rolling speed is determined in accordance with a required acceleration rate change obtained by multiplying the deviation between the outlet temperature of the rolled material and the target outlet temperature by the first influence coefficient. An outlet side temperature control method for a hot rolling mill, wherein the outlet side temperature is changed to control the outlet side temperature within an allowable range. 8. The method for controlling the outlet temperature of a hot rolling mill according to claim 7, wherein the rolling speed is changed according to a result of multiplying a required acceleration rate change amount by a predetermined tuning rate. An outlet temperature control method for a hot rolling mill, wherein the outlet temperature is controlled within an allowable range, and the tuning ratio is adjusted according to the actual accuracy of the outlet temperature by this control. 9. A method for controlling an outlet temperature of a hot rolling mill having a plurality of continuous rolling stands and a spray for discharging cooling water between the rolling stands, wherein a change in spray water amount with respect to a change in outlet temperature is determined in advance. The spraying water amount is changed according to the required water amount change amount obtained by multiplying the deviation between the outlet side temperature of the rolled material and the target outlet side temperature and the second influence coefficient. An outlet temperature control method for a hot rolling mill, wherein the outlet temperature is controlled within an allowable range. 10. The method for controlling the outlet temperature of a hot rolling mill according to claim 9, wherein a spray water amount is changed according to a result of multiplying a required water amount change amount by a predetermined tuning rate, and a rolled material is output. While controlling the side temperature within the allowable range,
An outlet temperature control method for a hot rolling mill, wherein the above-mentioned tuning ratio is adjusted according to the actual accuracy of the outlet temperature by this control. 11. The method according to claim 9 or 10, wherein control is performed by changing the spray cooling amount stepwise by the outlet temperature control method of the hot rolling mill, and control between the steps is performed. An outlet side temperature control method for a hot rolling mill, wherein the outlet side temperature control method according to claim 8 is used to control the outlet speed by changing the rolling speed. 12. The hot working according to claim 9, wherein the outlet temperature of the rolled material is higher than the target outlet temperature, or when the outlet temperature exceeds a predetermined allowable upper limit. Control by changing the spray cooling amount using the outlet temperature control method of the rolling mill, if the outlet temperature of the rolled material is lower than the target outlet temperature, or if the outlet temperature is lower than the predetermined allowable range lower limit If the temperature is lower, an outlet temperature control method for a hot rolling mill, wherein control is performed by changing the rolling speed using the outlet temperature control method for a hot rolling mill according to claim 7 or 8. 13. An outlet temperature control device for a hot rolling mill using the outlet temperature control method for a hot rolling mill according to any one of claims 1 to 12.