Control system and control method for continuous rolling machine

Abstract

The art of the present disclosure is applied to a control system for a continuous rolling machine comprising a rolling stand. The control system according to the present disclosure comprises a storage device for holding training data calculated on the basis of time-series data acquired during rolling. The control system calculates a set value of the roller speed of the rolling stand on the basis of the training data, acquires a correction command value performed on the set value while the steel sheet is passing through the continuous rolling mill, and updates the training data on the basis of the acquired correction command value.

Description

Continuous rolling mill control system and control method

[0001] The present disclosure relates to a control system and a control method for a continuous rolling mill having rolling stands.

[0002] In technical fields such as hot finish rolling, a continuous rolling mill equipped with a plurality of rolling stands is used. Patent Document 1 discloses a control device for a hot tandem rolling mill that controls a hot rolling mill equipped with a plurality of rolling stands and controls values ​​such as the tension of a steel plate to desired values.

[0003] Patent No. 5783925

[0004] In a continuous rolling mill, when the leading edge of a steel plate fed from an upstream rolling stand is caught in a downstream rolling stand, if the downstream rolling stand pulls the steel plate in slowly, the plate may loosen between the rolling stands, causing problems with threading. Conversely, if the downstream rolling stand pulls the steel plate in slowly, the steel plate may be pulled between the rolling stands, causing a width defect known as width shrinkage. Therefore, in order to maintain an appropriate tension in the steel plate, it is necessary to control the roll speed of each rolling stand to an appropriate value.

[0005] The present disclosure has been made in view of the above-mentioned problems, and one object of the present disclosure is to provide a technique capable of improving the control accuracy of the roll speed of a rolling stand when a steel plate passes through a continuous rolling mill.

[0006] The technology of the present disclosure is applied to a control system for a continuous rolling mill. The control system of the present disclosure includes one or more processors and a storage device that stores learning data calculated based on time-series data acquired during rolling. The one or more processors calculate a set value for the roll speed of a rolling stand based on the learning data, acquire a value of a correction command made to the set value while the steel plate is passing through the continuous rolling mill, and update the learning data based on the acquired value of the correction command.

[0007] The technology of the present disclosure is applied to a control method for a continuous rolling mill. The control method of the present disclosure is characterized by including: calculating a set value of the roll speed of a rolling stand based on learning data calculated from time-series data acquired during past rolling; acquiring a value of a correction command made to the set value while the steel plate is passing through the continuous rolling mill; and updating the learning data based on the acquired value of the correction command.

[0008] According to the control system and control method of the present disclosure, the roll speed of a rolling stand is set based on learning data. The learning data is also updated based on the value of a correction command. The value of the correction command is the value of a correction command made to the set value of the roll speed while the steel sheet is passing through the continuous rolling mill. By using the learning data updated in this manner, it is possible to set a roll speed that will provide an appropriate tension when the steel sheet passes through the continuous rolling mill, without relying on the accuracy of the rolling model. This makes it possible to improve the control accuracy of the roll speed.

[0009] FIG. 1 is a block diagram showing an example configuration of a control system according to an embodiment of the present disclosure. FIG. 2 is a block diagram showing an example configuration of functions possessed by a control system according to an embodiment of the present disclosure. FIG. 3 is a diagram for explaining the operation of a rolling stand and a looper when a steel plate passes through a continuous rolling mill. FIG. 4 is a block diagram showing an example of information flow in a setting step. FIG. 5 is a block diagram showing an example of information flow in a control step in the first embodiment. FIG. 6 is a block diagram showing another example of information flow in a control step in the first embodiment. FIG. 7 is a block diagram showing an example of information flow in a learning step. FIG. 8 is a block diagram showing an example of information flow in a control step in the second embodiment. FIG. 9 is a block diagram showing an example of information flow in a control step in the third embodiment. FIG. 10 is a block diagram showing an example of information flow in a control step in the fourth embodiment. FIG. 11 is a block diagram showing an example of information flow in a control step in the fifth embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0011] 1. Configuration of the Control System The system according to this embodiment is a control system for controlling a continuous rolling mill. The configuration of the control system will be described with reference to FIGS. 1 and 2.

[0012] The continuous rolling mill 200 comprises a plurality of rolling stands F1 to Fn and one or more loopers LP1 to LPm. n is any natural number equal to or greater than 2, and m is any natural number equal to or greater than 1. The rolling stands F1 to Fn and loopers LP1 to LPm are arranged so that one or more loopers are installed between each rolling stand. Note that, hereinafter, the symbols F1, F2, ... Fn will be used to indicate a specific rolling stand, but the symbol F will be used to refer to any rolling stand or to refer collectively. Similarly, the symbol L will be used to indicate a looper when referring to any looper or to refer collectively.

[0013] The control system 100 controls at least the roll speed of each rolling stand F. The control system 100 may also control the roll position of the rolling stand F and the looper angle of the looper LP. The control system 100 is connected to each rolling stand F and each looper LP via a control network 30.

[0014] 1 shows an example of the hardware configuration of a control system 100. The control system 100 includes a processor 101, a program memory 102, a data storage memory 103, a communication module 104, and a user interface 105. The processor 101 may be a CPU, a RISC, a DSP, an FPGA, an ASIC, a PLD, or another processing unit, may be a combination of two or more of these, or may be a dedicated processor for the control system 100. Although the present embodiment includes one processor 101, the control system 100 may include multiple processors 101.

[0015] The program memory 102 is communicatively coupled to the processor 101. The program memory 102 stores a program made up of a plurality of instructions INST that can be executed by the processor 101. The program made up of the instructions INST can be acquired using a computer-readable non-transitory storage medium or via a network. The program memory 102 may be built into the processor 101.

[0016] The data storage memory 103 is communicatively coupled to the processor 101. Learning data DATA is registered in the data storage memory 103. The learning data DATA is data for correcting the set value of the roll speed of the rolling stand F. The learning data DATA is calculated based on time series data acquired during past rolling. The time series data used to calculate the learning data DATA includes time series data on the value of the correction command. The data storage memory 103 may be built into the processor 101.

[0017] The communication module 104 is communicatively coupled to the processor 101. The communication module 104 is provided for communication with external devices, including a host computer 40 that determines rolling-related parameters such as product thickness.

[0018] The user interface 105 is communicatively coupled to the processor 101. The user interface 105 is provided so that an operator who manages the rolling line can input information. The operator can also input correction commands, which will be described later, via the user interface 105.

[0019] The functions of the control system 100 configured as described above will be explained using Figure 2. However, here, two adjacent rolling stands F and their associated functions are shown as representative of a continuous rolling mill. The control system 100 includes a rolling stand controller 2, a looper controller 3, a setting device 4, and a learning device 10. The functions of these devices are realized by reading instructions INST from a program memory 102 and executing them in a processor 101. The functions of each device may be configured by independent hardware, or one piece of hardware may have the functions of multiple devices.

[0020] A rolling stand controller 2 is provided for each rolling stand F. Only two rolling stand controllers 2 corresponding to two adjacent rolling stands F are shown in FIG. 2. The rolling stand controller 2 controls the rolling stands F. The rolling stand controller 2 includes at least a roll speed control unit 21 that controls the roll speed of the rolling stand F. The rolling stand controller 2 may also include a roll gap position control unit 22 that controls the roll gap position of the rolling stand F.

[0021] A looper control device 3 is provided for each looper LP. Fig. 2 shows only one looper control device 3 corresponding to the looper LP provided between two adjacent rolling stands F. The looper control device 3 controls the looper LP. For example, the looper control device 3 acquires the tension of the steel plate detected by the looper LP, and controls the looper angle and torque of the looper LP based on the acquired tension.

[0022] One setting device 4 is provided in the control system 100. All rolling stand controllers 2 and looper controllers 3 in the control system 100 are connected to this one setting device 4. The setting device 4 sets the roll speed of at least each rolling stand F and outputs the set values ​​to the roll speed control unit 21 corresponding to each rolling stand F. The setting device 4 may also set the roll gap position of each rolling stand F and the target angle value and target tension value of each looper LP, and output the set values ​​to the roll gap position control unit 22 corresponding to each rolling stand F and the looper controller 3 corresponding to each looper LP.

[0023] One learning device 10 is provided in the control system 100 corresponding to the setting device 4. The learning device 10 and the setting device 4 do not necessarily need to be separate devices and may be a single device. The learning device 10 includes a learning value storage unit 11, a learning value calculation unit 12, and a data collection unit 13. The learning value storage unit 11 stores, as learning data, learning values ​​for correcting the roll speed managed in the stratification table. Stratification is a concept of classifying rolling conditions such as the steel type, thickness, width, target thickness, and rolling stand number of the steel plate. For example, if there are m categories for steel type and n categories for width, the stratification table will be composed of m × n cells. The learning values ​​are coefficients for correcting the roll speed of each rolling stand, which are set based on a rolling model, and are calculated based on rolling results obtained in the past and stored in the learning value storage unit 11.

[0024] The learning value calculation unit 12 calculates a learning value for updating the learning data. The calculation by the learning value calculation unit 12 is performed every time rolling is completed, and the calculated learning value is recorded by updating the value of the cell that matches the rolling conditions of the material. The data collection unit 13 collects data for updating the learning data.

[0025] The operation of rolling stands F1 to Fn and loopers LP1 to LPm when a steel plate passes through the continuous rolling mill will be described with reference to Figure 3. In Figure 3, the left side is the upstream side of the continuous rolling mill and the right side is the downstream side. The vertical arrows indicate the passage of time.

[0026] The steel sheet is rolled to a predetermined thickness while moving from the upstream side to the downstream side of the continuous rolling mill. The steel sheet 1 fed into the continuous rolling mill is first engaged in rolling stand F1, then sent out from rolling stand F1 and engaged in rolling stand F2. Similarly, for rolling stand F2 and below, the steel sheet 1 sent out from rolling stand F is engaged in the adjacent rolling stand F on the downstream side, and this process is repeated until the steel sheet 1 is engaged up to rolling stand Fn.

[0027] Let us consider the tension of the steel sheet 1 between rolling stand Fi and rolling stand Fi+1 after the steel sheet 1 has been gripped by rolling stand Fi+1. i is any natural number satisfying the condition 1≦i≦n−1. The tension of the steel sheet 1 is determined by the balance of the delivery speeds of rolling stand Fi and rolling stand Fi+1. In other words, if the speed at which rolling stand Fi+1 draws in the steel sheet 1 is slower than the speed at which rolling stand Fi delivers the steel sheet 1, the steel sheet 1 will sag, and if it is faster, the steel sheet 1 will tensed. The delivery speed of rolling stand F is determined by the roll speed. Excessive sagging or tensing of the steel sheet 1 may cause threading problems, so the roll speed of rolling stand F is controlled so that the tension of the steel sheet 1 is appropriate.

[0028] Furthermore, in order to mitigate changes in the tension of the steel sheet 1, a looper LP is provided between the rolling stand Fi and the rolling stand Fi+1, and by changing the looper angle of the looper LPi, it is possible to increase or decrease the path length of the steel sheet 1 as it passes between the rolling stand Fi and the rolling stand Fi+1. After the steel sheet 1 has been caught in the rolling stand Fi+1, the looper LPi provided between the rolling stand Fi and the rolling stand Fi+1 rises up to adjust the path length of the steel sheet 1 between the rolling stand Fi and the rolling stand Fi+1.

[0029] The roll speed of the rolling stand F is determined based on a set value calculated before the steel sheet 1 is fed into the rolling stand F1 and the value of a correction command received during rolling. The set value is calculated by a setting device 4 and sent to the rolling stand control device 2. In addition, the correction command is issued from the looper LP or the adjacent rolling stand F.

[0030] Regarding the correction command issued from the looper LP, after the looper LP has risen, a correction command is issued to correct the roll speed of the rolling stand Fi located upstream of the looper LP or the rolling stand Fi+1 located downstream of the looper LP, based on the angle of the looper LP or the tension detected in the looper LP.

[0031] Furthermore, if the roll speed of any of the rolling stands F is corrected after the steel sheet 1 has been gripped by the rolling stands F3 and onwards, the tension between the rolling stands F further upstream or downstream will also change accordingly. Therefore, the roll speed correction must be carried out in a chain reaction on the rolling stands further upstream or downstream. A correction command is issued from the rolling stand F in such a situation.

[0032] The chain of roll speed corrections is performed with the pivot stand at the center. The pivot stand is a main stand, and any one of the multiple rolling stands F1 to Fn can be the pivot stand. Changes in the roll speeds of the rolling stands F1 to Fn throughout the continuous rolling mill are reflected throughout the entire continuous rolling mill by changing the roll speed starting from the pivot stand and propagating a speed correction command to adjacent rolling stands. Furthermore, when a correction command for tension control is issued upstream (or downstream) of the pivot stand, the correction command is propagated to rolling stands further upstream (or downstream) away from the pivot stand.

[0033] By adjusting the roll speed of the rolling stand Fi or Fi+1 in this manner, the tension of the steel sheet 1 between the rolling stand Fi and the rolling stand Fi+1 is controlled.

[0034] 2. First Embodiment A control system 100 in a first embodiment will be described. The operations performed by the control system 100 can be divided into three steps, a setting step, a control step, and a learning step, depending on the operation timing. The setting step is a step performed before the leading edge of the steel plate 1 reaches the continuous rolling mill. The control step is a step that starts after the leading edge of the steel plate 1 reaches the continuous rolling mill and ends after the tail end of the steel plate 1 has passed through the continuous rolling mill. The learning step is a step that is performed after the tail end of the steel plate 1 has passed through the continuous rolling mill.

[0035] 4 shows the flow of information in the setting step. In the setting step, in order to realize various product requirements regarding steel type, dimensions, etc., calculations are performed using a rolling model and learning data, and a set value for the roll speed of the rolling stand F is calculated. In the setting step, set values ​​for the roll gap position of the rolling stand F, and the target angle and target tension of the looper LP may also be calculated.

[0036] The set value is calculated by the setting device 4. The setting device 4 inputs stratification information to a learned value storage unit 11. The stratification information is stored in a stratification information memory of the setting device 4. Upon receiving the stratification information, the learned value storage unit 11 searches a stratification table based on the stratification information and outputs the obtained learned value to the setting device 4. The setting device determines the set value by calculation using a rolling model or by table indexing, based on the learned value and the steel plate specifications provided by the upper computer 40.

[0037] The setting device 4 calculates the roll position and roll speed of the rolling stand F, as well as the target value of the looper angle of the looper LP and the target value of the tension of the steel plate 1 in the looper LP, based on the calculation results from the rolling model and the learning values ​​acquired from the learning device 10, and outputs them to the rolling stand control device 2 and the looper control device 3.

[0038] 5 and 6 are diagrams showing the flow of information in the control steps. Here, the explanation will be given on the assumption that the pivot stand is the final rolling stand Fn, i.e., that the more upstream the rolling stand, the farther it is from the pivot stand. However, any rolling stand F other than the final rolling stand Fn may be used as the pivot stand.

[0039] In the control step, the roll speed of the rolling stand F is controlled. The roll speed control section 21 of the rolling stand control device 2 calculates a speed correction command for controlling the roll speed of the rolling stand F based on the roll speed setting value given by the setting device 4 in the setting step and the value of the correction command given during the control step, and controls the roll speed of the rolling stand F based on the calculation result. The speed correction command is calculated, for example, as a ratio of the speed change amount to the roll speed setting value.

[0040] The speed correction command is output from the looper control device 3, which controls the looper LP located behind the rolling stand F, and the roll speed control unit 21 of the rolling stand control device 2, which controls the adjacent downstream rolling stand F, in order to control the tension of the steel plate 1.

[0041] 5 shows a scene where a correction command is output from the looper control device 3. The looper control device 3 controls the torque of the looper LP based on target values ​​for at least one of the looper angle and the tension of the steel sheet 1 in the looper LP given by the setting device 4 before rolling and actual values ​​for at least one of the looper angle and the tension of the steel sheet 1 acquired from the looper LP during the control step, and outputs a correction command to the rolling stand control device 2 that controls the upstream rolling stand F when the target values ​​do not match the actual values. The looper LP is controlled, for example, by PI control using only the looper angle or ILQ control using both the looper angle and the tension.

[0042] In addition, the rolling stand control device 2 outputs a new correction command to the rolling stand control device 2 that controls the adjacent upstream rolling stand F, in accordance with the speed change amount changed based on the correction command.

[0043] 6 shows a scene in which a correction command is output from an adjacent rolling stand controller 2. When the adjacent downstream rolling stand controller 2 receives the correction command and corrects the roll speed of the rolling stand F, a correction command is output from the adjacent downstream rolling stand F to the rolling stand F.

[0044] In this case too, the rolling stand control device 2 outputs a new correction command to the rolling stand control device 2 that controls the adjacent upstream rolling stand F, in accordance with the amount of speed change that has been changed based on the correction command.

[0045] Furthermore, during the control step, the data collection unit 13 of the learning device 10 constantly collects and stores performance data of speed correction commands for tension control from the rolling stand control device 2.

[0046] The same applies to the case where the pivot stand is a rolling stand other than the final rolling stand Fn. In this case, the output destination of the correction command from the rolling stand controller 2 and the looper controller 3 is the rolling stand controller 2 on the side farther from the pivot stand.

[0047] 7 is a diagram showing the flow of information in the learning step. In the learning step, the learning values ​​of the learning data are updated. The learning value calculation unit 12 of the learning device 10 calculates a learning value for correcting the roll speed of each rolling stand F based on the performance data stored by the data collection unit 13 during the control step.

[0048] The calculation of the learning value is performed, for example, as follows: First, the learning value calculation unit 12 acquires time-series data of the speed correction command for tension control of the rolling stand F from the data collection unit 13, and calculates the average value of the speed correction command in a pre-specified sample section as the learning value for the material. This calculation is expressed by equation (1).

[0049]

[0050] Next, the learned value used for the material is obtained from the learned value storage unit 11 and an updated learned value is calculated using, for example, equation (2).

[0051]

[0052] Finally, the learning value calculation unit 12 outputs the updated learning value to the learning value storage unit 11. The learning value storage unit 11 searches the stratification table based on the stratification information of the steel sheet 1 that has been rolled in the control step, and updates the learning value in the corresponding stratification table with the updated learning value provided by the learning value calculation unit 12.

[0053] The control system 100 in the first embodiment has been described above. Below, second to fifth embodiments will be described as other embodiments of the control system 100. In the second to fifth embodiments described below, values ​​acquired in the control steps are different. Other configurations are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0054] 3. Second Embodiment Fig. 8 is a diagram for explaining the control steps in the second embodiment. In the second embodiment, during the control steps, the data collection unit 13 not only collects actual data from the rolling stand control device 2 every moment, but also collects and stores actual data of the looper angle from the looper control device 3 every moment. Then, in the learning step, the stored actual data is output to the learning device 10.

[0055] In the second embodiment, instead of specifying the sample interval in advance in the calculation of the learning value by the learning value calculation unit 12, the sample interval is determined to be an interval in which the fluctuation of the looper angle is small, i.e., an interval in which the tension control is stable. For example, the fluctuation of the looper angle is evaluated based on the equations (3) to (5), and the k where the evaluation value is minimum is determined. ｓｔａｒｔ Here, the length of the sample section may be specified in advance, or multiple lengths may be prepared and the length that minimizes the evaluation value may be selected.

[0056] The calculations for determining the sample interval are expressed by the following equations (3) to (5).

[0057]

[0058] Furthermore, since the mass flow situation changes during threading when the reduction position is changed for thickness control, it is better to position the sample section closer to the leading edge. Therefore, calculations may be performed using equations (6) and (7), which add a term f(k) that guides the leading edge to equation (3). Any function that increases with increasing k can be used for f(k). In the example of equation (7), f(k) is a linear function of coefficient α, where α is an adjustment coefficient.

[0059]

[0060] 4. Third Embodiment Fig. 9 is a diagram for explaining the control steps in the third embodiment. The third embodiment is a modified example of the second embodiment. In the third embodiment, the sample section is determined based on the actual data of the looper tension instead of the looper angle used in the calculations of equations (3) to (7). During the control steps, the data collection unit 13 not only collects actual data from the rolling stand control device 2 every moment, but also collects and stores actual data of the looper tension every moment from the looper control device 3.

[0061] The acquired performance data is output to the learning device 10 in the learning step.

[0062] 5. Fourth Embodiment Fig. 10 is a diagram for explaining the control steps in a fourth embodiment. During the control steps, the roll speed control unit 21 of the rolling stand control device 2 generates a speed correction command in response to a speed change manually performed by an operator, and calculates a speed correction command for final tension control based on the generated speed correction command, thereby controlling the roll speed of the rolling stand F. The fourth embodiment can be combined with any of the first to third embodiments.

[0063] 6. Fifth Embodiment Figure 11 is a diagram for explaining the control steps in the fifth embodiment. When the roll gap position of the rolling stand F is changed during the control steps, the roll gap position control unit 22 acquires the changed roll gap position. Then, a roll speed correction command for tension control corresponding to the changed roll gap position is generated, and the correction command value is provided to the roll speed control unit 21 in the rolling stand control device 2 in which the roll gap position control unit 22 is provided. The roll speed control unit 21 of the rolling stand control device 2 generates a speed correction command corresponding to the correction command value provided by the roll gap position control unit 22, and calculates a speed correction command for final tension control based on the generated speed correction command, thereby controlling the roll speed of the rolling stand F.

[0064] The fifth embodiment can be combined with the first to fourth embodiments.

[0065] 7. Effects Each embodiment of the present invention has been described above. As described above, in the present invention, the roll speed is not set based on the constant mass flow law, but rather the roll speed correction amount obtained in past rolling operations is used. This makes it possible to optimize the tension of the steel plate between rolling stands without relying on the accuracy of the rolling model, thereby realizing an increase in production volume by reducing plate threading problems and an improvement in yield by preventing excessive tension.

[0066] DATA Learning data INST Instruction F Rolling stand LP Looper 1 Steel plate 2 Rolling stand control device 3 Looper control device 4 Setting device 10 Learning device 11 Learning value storage unit 12 Learning value calculation unit 13 Data collection unit 21 Roll speed control unit 22 Rolling position control unit 30 Control network 40 Host computer 100 Control system 101 Processor 102 Program memory 103 Data storage memory 104 Communication module 105 User interface 200 Continuous rolling mill

Claims

1. A control system for a continuous rolling mill, comprising one or more processors and a storage device that holds learning data calculated based on time-series data acquired during rolling. The one or more processors calculate a set value for the roll speed of a rolling stand based on the learning data, acquire a value of a correction command made with respect to the set value while a steel sheet is passing through the continuous rolling mill, and update the learning data based on the acquired value of the correction command. A control system characterized by the above.

2. The control system according to claim 1, wherein the rolling stand includes a first rolling stand and a second rolling stand adjacent to the first rolling stand on the side opposite to the pivot stand. The one or more processors control the roll speed for each of the first rolling stand and the second rolling stand based on the set value of the roll speed, and generate speed correction information for correcting the roll speed of the second rolling stand based on speed correction information given to the first rolling stand. The correction command includes speed correction information for correcting the roll speed of the second rolling stand. A control system characterized by the above.

3. The control system according to claim 1, wherein the one or more processors generate speed correction information for correcting the roll speed of the rolling stand based on a difference between a target value and an actual value of a loop angle for controlling a loop located on the side of the pivot stand with respect to the rolling stand, or a difference between a target value of the tension of a steel sheet passing through the continuous rolling mill and an actual value acquired at the loop. The correction command includes speed correction information for correcting the roll speed of the rolling stand. A control system characterized by the above.

4. The control system according to claim 1, wherein the correction command includes a correction command for the roll speed manually input by an operator. A control system characterized by the above.

5. The control system according to claim 1, wherein the one or more processors generate speed correction information for correcting the roll speed corresponding to the changed screw-down position when the screw-down position of the rolling stand is changed while the steel sheet is passing through the continuous rolling mill, and the correction command includes the speed correction information for correcting the roll speed. A control system characterized by the above.

6. The control system according to any one of claims 1 to 5, wherein the one or more processors acquire time-series data of the looper angle of a looper located on the side of the pivot stand with respect to the rolling stand while the steel sheet is passing through the continuous rolling mill, and based on the time-series data of the looper angle, determine a sample section for acquiring the correction command for updating the learning data. A control system characterized by the above.

7. The control system according to any one of claims 1 to 5, wherein the one or more processors acquire time-series data of the tension of the steel sheet obtained in a looper located on the side of the pivot stand with respect to the rolling stand while the steel sheet is passing through the continuous rolling mill, and based on the time-series data of the tension, determine a sample section for acquiring the correction command for updating the learning data. A control system characterized by the above.

8. A control method for a continuous rolling mill, comprising calculating a set value of the roll speed of a rolling stand based on learning data calculated based on time-series data acquired during past rolling, acquiring a value of a correction command performed on the set value while the steel sheet is passing through the continuous rolling mill, and updating the learning data based on the acquired value of the correction command. A control method characterized by the above.

9. The control method according to claim 8, wherein the rolling stand includes a first rolling stand and a second rolling stand adjacent to the first rolling stand on the side opposite to the pivot stand, and the control method includes: controlling the roll speed for each of the first rolling stand and the second rolling stand based on the set value of the roll speed; and generating speed correction information for correcting the roll speed of the second rolling stand based on the speed correction information given to the first rolling stand. The correction command includes speed correction information for correcting the roll speed of the second rolling stand. A control method characterized by the above.

10. The control method according to claim 8, further including generating speed correction information for correcting the roll speed of the rolling stand based on the difference between the target value and the actual value of the loop angle for controlling the loop located on the side of the pivot stand with respect to the rolling stand, or based on the difference between the target value of the tension of the steel sheet passing through the continuous rolling mill and the actual value obtained in the loop. The correction command includes speed correction information for correcting the roll speed of the rolling stand. A control method characterized by the above.

11. The control method according to claim 8, wherein the correction command includes a correction command for the roll speed manually input by an operator. A control method characterized by the above.

12. The control method according to claim 8, further including generating speed correction information for correcting the roll speed corresponding to the changed reduction position when the reduction position of the rolling stand is changed while the steel sheet is passing through the continuous rolling mill. The correction command includes speed correction information for correcting the roll speed. A control method characterized by the above.

13. The control method according to any one of claims 8 to 12, further including: acquiring time-series data of the loop angle of the loop located on the side of the pivot stand with respect to the rolling stand while the steel sheet is passing through the continuous rolling mill; and determining a sample section for acquiring the correction command for updating the learning data based on the time-series data of the loop angle. A control method characterized by the above.

14. The control method according to any one of claims 8 to 12, further comprising: obtaining time-series data of the tension of the steel sheet acquired in a looper located on the side of the pivot stand with respect to the rolling stand while the steel sheet is passing through the continuous rolling mill; and determining a sample section for obtaining the correction command for updating the learning data based on the time-series data of the tension. A control method characterized by the above.

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