Leveling control method in hot rolling, leveling control device, hot rolling equipment, and method for manufacturing hot rolled steel strip

Abstract

To provide a leveling control method in hot rolling which dissolves a meander factor before meandering appears, prevents meander of a rolled material, and can stabilize passing of the rolled material.SOLUTION: A leveling control method in hot rolling includes: a first leveling correction amount calculation step (step S3) of calculating a first leveling correction amount ΔLv1 in a rolling machine Fn that is an object to be controlled, on the basis of a width direction deviation ΔT of tension in a steady part of a rolled material S, while a tail end of the rolled material S passes through a rolling machine Fn-1 in the preceding stage after a tip of the rolled material S has passed through the rolling machine Fn that is the object to be controlled; and a second leveling correction amount calculation step (step S7) of calculating a second leveling correction amount ΔLv2 in the rolling machine Fn that is the object to be rolled, on the basis of a meander amount δi of the rolled material, and a differential load ΔP between the work side and the drive side of the rolling machine Fn that is the object to be controlled, while the tail end of the rolled material S passes through a meander amount detection device 15 after having passed through the rolling machine Fn-1 in the preceding stage.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a leveling control method in hot rolling, a leveling control device, a hot rolling facility, and a method for producing a hot rolled steel strip. [Background technology]

[0002] Generally, in a hot rolling facility, a slab (rolled material) is heated to a predetermined temperature in a heating furnace, the heated slab (rolled material) is roughly rolled to a predetermined thickness in a roughing mill to form a sheet bar (rolled material), and then the sheet bar (rolled material) is finish-rolled to the predetermined thickness in a finishing rolling facility equipped with multiple rolling mills. The finish-rolled sheet bar (rolled material) becomes a hot-rolled steel strip of a predetermined thickness, and is cooled in a run-out table (cooling facility) installed downstream of the finishing rolling facility. The hot-rolled steel strip is then wound into a coil by a winder to be manufactured.

[0003] Here, when a rolled material is rolled in a finishing rolling facility equipped with a plurality of rolling mills, a phenomenon may occur in which the position of the rolled material in the width direction meanders toward the working side or the driving side with respect to the center of the rolling mill. The driving side is the side where the driving motor for the rolling rolls is attached, and the working side is the side opposite to the driving side. When meandering of the rolled material occurs, the width end of the rolled material comes into contact with the side guide, and the rolled material is rolled in a buckling state, resulting in a squeezing phenomenon. When the squeezing phenomenon occurs, scratches are caused on the rolling rolls, and maintenance work or replacement work for the rolling rolls is required, resulting in a decrease in productivity. Therefore, a technology for controlling the meandering of the rolled material during continuous rolling and passing the sheet through the mill center (the center of the rolling mill) as much as possible is essential in order to prevent the above-mentioned troubles, and is important from the viewpoints of improving productivity and suppressing production costs. In particular, meandering and squeezing of the rolled material occurs when the tail end of the rolled material passes through the rolling mill preceding the rolling mill to be controlled and the constraint between the rolling mills is removed, and therefore control of the meandering of the rolled material after the tail end of the rolled material passes through the preceding rolling mill becomes particularly important.

[0004] As methods for controlling the meandering of such rolled material, there are known in the prior art a method for controlling the meandering of a rolled material as disclosed in Patent Document 1, a method for controlling the meandering of a rolled steel plate as disclosed in Patent Document 2, and a hot rolling method as disclosed in Patent Document 3.

[0005] The method for controlling the meandering of a rolled material shown in Patent Document 1 includes a sensor-based meandering control process in which feedback control is performed based on the meandering amount of the rolled material detected by the meandering amount detection sensor from when the tail end of the rolled material passes a first point until it passes a point where the meandering amount detection sensor is provided between the rolling mill to be controlled and the rolling mill located one stage before the rolling mill to be controlled, thereby controlling the reduction amounts of the drive side and the work side of the rolling mill to be controlled; and a differential load type meandering control process in which feedback control is performed based on the differential load between the drive side and the work side of the rolling mill to be controlled, from when the tail end of the rolled material passes a second point, which is a point downstream of the first point and upstream of the point where the meandering amount detection sensor is provided, until it passes the point where the rolling mill to be controlled is located. In the sensor-based meandering control process, feedback control is performed with a second control gain smaller than the first control gain from when the tail end of the rolled material passes the first point until when it passes the second point, and feedback control is performed with the first control gain from when the tail end of the rolled material passes the second point until when it passes the point where the meandering amount detection sensor is provided. In the differential load-based meandering control process, feedback control is performed with a fourth control gain smaller than the third control gain from when the tail end of the rolled material passes the second point until when it passes the point where the meandering amount detection sensor is provided, and feedback control is performed with the third control gain from when the tail end of the rolled material passes the point where the meandering amount detection sensor is provided until when it passes the point where the rolling mill to be controlled is located.

[0006] Moreover, in the method for controlling the meandering of a rolled steel sheet shown in Patent Document 2, the amount of meandering is detected by a meandering meter provided on the entry side of the rolling mill, and the leveling amount is changed to an amount obtained by multiplying the amount of meandering by a control gain, in which the control gain is determined according to the rolling load.

[0007] In addition, the hot rolling method shown in Patent Document 3 includes a plurality of split rolls between rolling mills that can come into contact with a steel strip, and when the split rolls come into contact with the steel strip, a torque detector detects the torque acting on both the left and right ends of the split rolls, and based on the detected torque, adjusts the rolling leveling of the rolling mill to control the meandering of the steel strip and the plate shape. The meandering of the steel strip occurs due to the difference in the reduction ratio between the working side and the driving side of the rolling rolls, and the tension between the rolling mills is smaller on the side with a larger reduction ratio. For this reason, in the hot rolling method shown in Patent Document 3, the detected torque difference (tension difference) between both the left and right ends (the working side and the driving side end) is detected by the split rolls (looper rolls) between the rolling mills, and the leveling amount is controlled so that the detected torque difference (tension difference) between the left and right ends is eliminated, thereby preventing the occurrence of meandering. Leveling refers to the difference in the opening between the roll gap on the working side and the roll gap on the driving side of a rolling mill. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2013-212523 A [Patent Document 2] JP 2004-306125 A [Patent Document 3] International Publication No. 2012 / 086043 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the conventional method for controlling the meandering of a rolled material disclosed in Patent Document 1, the method for controlling the meandering of a rolled steel sheet disclosed in Patent Document 2, and the hot rolling method disclosed in Patent Document 3 have the following problems. That is, in the case of the method for controlling the meandering of a rolled material shown in Patent Document 1, meandering control using the meandering meter method (sensor-type meandering control process) is performed from when the tail end of the rolled material passes a first point until it passes a point where a meandering amount detection sensor is provided, and meandering control using the differential load method (differential load type meandering control process) is performed from when the tail end of the rolled material passes a second point until it passes a point where a rolling mill to be controlled is located. The meandering amount in this meandering meter type meandering control is detected by the meandering amount detection sensor after the meandering of the rolled material becomes apparent, and the differential load in the meandering control using the differential load method is detected as a result of the meandering amount detected after the meandering becomes apparent. For this reason, the method of controlling meandering of a rolled material shown in Patent Document 1, which performs meandering control using a meander meter type meandering control, which corrects the leveling control of the rolling mill to be controlled based on the amount of meandering, and a differential load type meandering control, which corrects the leveling control of the rolling mill to be controlled based on a differential load, has the problem that it is difficult to prevent meandering of the rolled material in advance.

[0010] Furthermore, the method of controlling the meandering of a rolled steel sheet shown in Patent Document 2 also involves the same problems as the method of controlling the meandering of a rolled material shown in Patent Document 1, since the meandering control is performed using a meander gauge. On the other hand, the response of leveling control can be made faster by setting large the control gains for the meandering amount and the differential load in the method for controlling the meandering of a rolled material shown in Patent Document 1, and by setting large the control gain for the meandering amount in the method for controlling the meandering of a rolled steel plate shown in Patent Document 2. However, when these control gains are set large to control leveling in the rolling mill to be controlled, over-control often occurs, making the threading of the rolled material unstable.

[0011] In hot finish rolling, as described above, meandering of the rolled material occurs and squeezing occurs when the constraint between the rolling mills is removed after the tail end of the rolled material passes through the rolling mill that is the previous stage of the rolling mill that is the controlled mill. Therefore, if the tail end of the rolled material is rolled by the controlled rolling mill with the leveling amount corrected in the steady part of the rolled material from when the front end of the rolled material passes through the controlled rolling mill until the tail end of the rolled material passes through the rolling mill that is the previous stage of the controlled rolling mill according to the hot rolling method shown in Patent Document 3 (i.e., with the differential tension control), the tail end has a different load from the steady part, so meandering may occur.

[0012] Therefore, the present invention has been made to solve these conventional problems, and an object of the present invention is to provide a leveling control method in hot rolling, a leveling control device, hot rolling equipment, and a manufacturing method for hot rolled steel strip, which can eliminate the causes of meandering before the meandering becomes apparent, thereby preventing the meandering of the rolled material, and stabilize the passing of the rolled material to reduce the amount of meandering of the rolled material. [Means for solving the problem]

[0013] In order to solve the above-mentioned problems, a leveling control method in hot rolling according to one aspect of the present invention is a leveling control method in hot rolling for controlling meandering of a rolled material rolled in a finishing rolling facility equipped with a plurality of rolling mills, the method comprising the steps of: controlling a meandering of a rolled material being rolled in a finishing rolling facility equipped with a plurality of rolling mills; and controlling a width direction distribution of a tension in a steady portion of the rolled material, the width direction distribution of a tension in a steady portion of the rolled material being detected by a tension detector installed between the rolling mill in the preceding stage and the rolling mill in the preceding stage, during a period from when a front end of the rolled material passes through a rolling mill to be controlled among the plurality of rolling mills until a tail end of the rolled material passes through a rolling mill in the preceding stage with respect to the rolling mill in the preceding stage, the tension in a steady portion of the rolled material being detected by a tension detector installed between the rolling mill in the preceding stage and .... a first leveling correction amount calculation step of calculating a first leveling correction amount in the rolling mill to be controlled based on a width direction deviation of tension in a steady portion of the rolled material; and a second leveling correction amount calculation step of calculating a first leveling correction amount in the rolling mill to be controlled based on a meandering amount of the rolled material detected by a meandering amount detection device installed between the rolling mill to be controlled and a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, the difference load being detected by a load detector installed in the rolling mill to be controlled, during a period from when the tail end of the rolled material passes through the rolling mill to when it passes through the meandering amount detection device installed between the rolling mill to be controlled and the work side and the drive side of the rolling mill to be controlled. a second leveling correction amount calculation step of calculating a second leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, which are detected by the load detector during a period from when the tail end of the rolled material passes through the meandering amount detection device until when it passes through the rolling mill to be controlled; and a third leveling correction amount calculation step of calculating a third leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, which are detected by the load detector during a period from when the front end of the rolled material passes through the rolling mill to be controlled until when the tail end of the rolled material passes through the rolling mill to be controlled. a leveling correction of the first leveling correction amount by adding the second leveling correction amount to the first leveling correction amount in a second control section from when the tail end of the rolled material passes through the previous rolling mill to when it passes through the meandering amount detection device; and a leveling correction of the first leveling correction amount and the second leveling correction amount by adding the third leveling correction amount to the first leveling correction amount and the second leveling correction amount in a third control section from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled.and a leveling control step of controlling the leveling of the rolling mill to be controlled.

[0014] A leveling control device in hot rolling according to another aspect of the present invention is a leveling control device in hot rolling that controls the meandering of a rolled material being rolled in a finishing rolling facility equipped with a plurality of rolling mills, and includes a leveling control device that controls the meandering of a rolled material being rolled in a finishing rolling facility equipped with a plurality of rolling mills, and controls a width direction distribution of tension in a steady portion of the rolled material calculated from a width direction distribution of tension in the steady portion of the rolled material detected by a tension detector installed between the preceding rolling mill and the preceding rolling mill during a period from when a leading end of the rolled material passes through a controlled rolling mill among the plurality of rolling mills to when a tail end of the rolled material passes through a preceding rolling mill with respect to the controlled rolling mill. a first leveling correction amount calculation unit that calculates a first leveling correction amount at the rolling mill to be controlled based on a directional deviation; and a second leveling correction amount at the rolling mill to be controlled based on a meandering amount of the rolled material detected by a meandering amount detection device installed between the rolling mill to be controlled and a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled detected by a load detector installed in the rolling mill to be controlled, during a period from when the tail end of the rolled material passes through the rolling mill to when it passes through the meandering amount detection device installed between the rolling mill to be controlled and the work side and drive side of the rolling mill to be controlled detected by a load detector installed in the rolling mill to be controlled. a third leveling correction amount calculation unit which calculates a third leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, detected by the load detector, during a period from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled; and a third leveling correction amount calculation unit which calculates a third leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, detected by the load detector, during a period from when the tail end of the rolled material passes through the rolling mill to when it passes through the rolling mill to be controlled. and a leveling control unit that controls leveling of the rolling mill to be controlled so that in a second control section from when the tail end of the rolled material passes through the rolling mill to when it passes through the meandering amount detection device, a leveling correction amount obtained by adding the second leveling correction amount to the first leveling correction amount is performed, and in a third control section from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled, a leveling correction amount obtained by adding the first leveling correction amount and the second leveling correction amount to the third leveling correction amount.

[0015] A hot rolling facility according to another aspect of the present invention includes the above-mentioned leveling control device. Furthermore, a method for producing a hot rolled steel strip according to another aspect of the present invention is characterized in that it includes a finish rolling step in which the meandering of the rolled material is controlled using the above-mentioned leveling control method and the rolled material is finish rolled. Effect of the Invention

[0016] According to the leveling control method in hot rolling, leveling control device, hot rolling equipment, and method for manufacturing hot rolled steel strip of the present invention, differential tension control is performed in the steady portion of the rolled material from when the front end of the rolled material passes through the rolling mill to be controlled to when the tail end of the rolled material passes through the rolling mill preceding the rolling mill to be controlled, thereby eliminating the cause of meandering before it becomes apparent, and after the rolled material has passed through the rolling mill preceding the rolling mill to be controlled, meandering control using a meander meter system and meandering control using a differential load system are performed to control meandering that occurs when the cause of meandering cannot be completely eliminated by differential tension control, thereby stabilizing the passing of the plate. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a hot rolling facility equipped with a leveling control device according to an embodiment of the present invention. [Diagram 2] 2 is a first half of a flowchart for explaining a process flow of the leveling control device shown in FIG. 1. [Diagram 3] 2 is a flow chart illustrating the second half of the process performed by the leveling control device shown in FIG. 1; [Figure 4] 2 is a diagram showing how a meandering amount prediction model is generated by a meandering amount prediction model generating unit of the leveling control device shown in FIG. 1. FIG. [Diagram 5] FIG. 13 is a diagram showing a processing flow of a meandering amount prediction model which is a neural network model. [Figure 6] FIG. 2 is a diagram for explaining leveling control in a rolling mill that is a control target and that performs leveling correction by the leveling control device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not limited to the following embodiments in terms of the materials, shapes, structures, arrangements, etc. of the components. In addition, the drawings are schematic, and therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc. may differ from the actual relationship between thickness and planar dimensions, and the drawings may include parts in which the relationship between dimensions and ratios differ from one another.

[0019] FIG. 1 shows a schematic configuration of a hot rolling facility equipped with a leveling control device according to one embodiment of the present invention. 1 includes a heating furnace 2 for heating a slab (rolled material) S to a predetermined temperature, a roughing mill 3 for rough rolling the slab (rolled material) S heated in the heating furnace 2 to a predetermined plate thickness to produce a sheet bar (rolled material) S, and a finish rolling facility 4 for finish rolling the sheet bar (rolled material) S to a predetermined plate thickness. The roughing mill 3 includes M rough rolling stands R1 to RM (M is a natural number of 2 or more).

[0020] The hot rolling equipment 1 also includes a runout table 5 for cooling the finish-rolled hot-rolled steel strip (rolled material) S, and a winder 6 for winding the cooled hot-rolled steel strip (rolled material) S into a coil. Here, the finishing rolling facility 4 is equipped with N rolling mills F1 to FN (N is a natural number of 4 or more), which finish roll the sheet bar (rolled material) S to a specified thickness by tandem rolling. Each of the rolling mills F1 to FN is equipped with a leveling device 7 (only the leveling device 7 installed in the rolling mill FN is shown) that adjusts the reduction amount on the operation side and the drive side. The rolled material S runs (is transported) in the direction shown by the arrow in FIG. 1. Note that the drive side of each of the rolling mills F1 to FN is the side where the drive motor for the rolling rolls is attached, and the working side is the opposite side to the drive side.

[0021] The finishing rolling facility 4 is also provided with a leveling control device 10 that controls the meandering of the rolled material S. The leveling control device 10 controls the meandering of the rolled material S by "means control using a differential tension method" at the controlled rolling mill Fn in a first control section A in a steady portion of the rolled material S from when the leading end of the traveling rolled material S passes through the nth (n is any number from 1 to N) controlled rolling mill Fn from the beginning to when the tail end of the rolled material S passes through the rolling mill Fn-1 preceding the controlled rolling mill Fn.

[0022] In addition, in the second control section B from when the tail end of the rolled material S passes through the upstream rolling mill Fn-1 until when it passes through the meandering amount detection device 15, which is installed between the upstream rolling mill Fn-1 and the controlled rolling mill Fn and will be described later, the leveling control device 10 controls the meandering of the rolled material S by using a combination of ``meandering control using a meandering meter method'' and ``meandering control using a differential load method'' at the controlled rolling mill Fn. Furthermore, the leveling control device 10 controls the meandering of the rolled material S at the controlled rolling mill Fn by "differential load type meandering control" in the third control section C from when the tail end of the rolled material S passes through the aforementioned meandering amount detection device 15 until it passes through the controlled rolling mill Fn.

[0023] Here, in this embodiment, the "wandering control using differential tension method" corrects the leveling amount (roll gap difference, which is the difference in the roll gap opening between the operating side and driving side in the rolling mill Fn) Lv in the controlled rolling mill Fn by a leveling correction amount proportional to the widthwise deviation of the tension in the steady portion of the rolled material S (tension difference between both widthwise ends (driving side and working side ends) in the steady portion of the rolled material S) calculated from the widthwise distribution of the tension in the steady portion of the rolled material S detected by a tension detector 11 described later, which is installed between the upstream rolling mill Fn-1 and the controlled rolling mill Fn. Specifically, as shown in FIG. 6, in the first control section A from when the front end of the rolled material S passes through the controlled rolling mill Fn to when the tail end of the rolled material S passes through the preceding rolling mill Fn-1, the leveling amount Lv at the controlled rolling mill Fn is corrected by a first leveling correction amount ΔLv1=α (α is a control gain in meandering control using a differential tension method)×ΔT, which is proportional to the widthwise deviation ΔT of the tension in the steady portion of the rolled material S calculated from the widthwise distribution of the tension in the steady portion of the rolled material S detected by a tension detector 11 installed between the preceding rolling mill Fn-1 and the controlled rolling mill Fn, to set the widthwise deviation of the tension to zero.

[0024] In the present embodiment, the "wandering control by the meandering meter method" corrects the leveling amount Lv of the rolling mill Fn to be controlled by a leveling correction amount proportional to the meandering amount detected by the meandering amount detection device 15 installed between the preceding rolling mill Fn-1 and the rolling mill Fn to be controlled. Specifically, as shown in Fig. 6, the leveling amount Lv of the rolling mill Fn to be controlled is corrected by adding a leveling correction amount γ (γ is a control gain in the meandering control by the meandering meter method) × δi, which is proportional to the meandering amount δi of the second leveling correction amount ΔLv2 detected by the meandering amount detection device 15, to the first leveling correction amount ΔLv1 in the second control section B from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 to when it passes through the meandering amount detection device 15, with respect to the preset leveling amount (lock-on value) LvL.

[0025] In addition, in this embodiment, the "wandering control using differential load method" corrects the leveling amount Lv of the rolling mill Fn to be controlled by a leveling correction amount proportional to a differential load (the difference between the rolling load on the working side and the rolling load on the driving side) calculated from the rolling loads on the working side and the driving side detected by a load detector 16 (described later) installed on the rolling mill Fn to be controlled. Specifically, as shown in FIG. 6, in the second control section B from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 to when it passes through the meandering amount detection device 15, the leveling amount Lv of the controlled rolling mill Fn is corrected by adding a leveling correction amount β (β is the control gain in meandering control using the differential load method) × ΔP / Mi (Mi is the parallel stiffness of the controlled rolling mill) which is proportional to the differential load ΔP calculated from the rolling loads on the working side and the driving side detected by the load detector 16 among the second leveling correction amount ΔLv2 to the first leveling correction amount ΔLv1 with respect to the preset leveling amount (lock-on value) LvL. Also, as shown in FIG. 6, in the third control section C from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled, the leveling amount Lv at the controlled rolling mill Fn is corrected by adding a third leveling correction amount ΔLv3=β×ΔP / Mi, which is proportional to the differential load ΔP calculated from the rolling loads on the working side and the driving side detected by the load detector 16, to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 with respect to the preset leveling amount (lock-on value) LvL.

[0026] If the meandering of the rolled material S occurs on the operating side, the leveling amount Lv is corrected (to the "-" side) so that the operating side closes, and if the meandering of the rolled material S occurs on the drive side, the leveling amount Lv is corrected (to the "+" side) so that the drive side closes. The leveling amount Lv is the difference in opening between the roll gap on the operation (OP) side of the rolling mills F1 to FN and the roll gap on the drive (DR) side. If the roll gap between the upper and lower work rolls on the operation (OP) side of the rolling mills F1 to FN is Lv_0p and the roll gap between the upper and lower work rolls on the drive (DR) side of the rolling mills F1 to FN is Lv_dr, then Lv is defined as Lv = Lv_0p - Lv_dr.

[0027] The leveling control device 10 will be described in detail below. As shown in FIG. 1, the leveling control device 10 includes a tension detector 11, a tension deviation calculation unit 12, a meandering amount detection device 15, a load detector 16, a differential load calculation unit 17, a first leveling correction amount calculation unit 18, a second leveling correction amount calculation unit 19, a third leveling correction amount calculation unit 20, a meandering amount prediction model generation unit 21, a meandering amount prediction unit 22, a judgment unit 23, a leveling correction amount correction unit 24, and a leveling control unit 25.

[0028] The tension detectors 11 are installed between each of the rolling mills from the first rolling mill F1 to the last rolling mill FN (only tension detectors 11 installed between the rolling mill Fn to be controlled and the rolling mill Fn-1 preceding it, and between the rolling mill Fn-1 preceding it and the rolling mill Fn-2 preceding it are shown in FIG. 1), and detect the widthwise distribution of the tension of the passing rolled material S. Each tension detector 11 is composed of a looper load cell equipped with load cells at both ends of the looper roll in the widthwise direction, and detects the load at one end of the rolled material S in the widthwise direction and the load at the other end of the rolled material S in the widthwise direction by the load cells installed at both ends of the looper roll in the widthwise direction, and calculates the widthwise distribution of the tension of the rolled material S from the two detected loads. The tension detector 11 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 detects the widthwise distribution of tension in the steady portion of the running rolled material S from the time when the leading end of the rolling material S passes through the rolling mill Fn to be controlled until the tail end of the rolling material S passes through the preceding rolling mill Fn-1.

[0029] The tension deviation calculation unit 12 is connected to each tension detector 11. The tension deviation calculation unit 12, connected to the tension detector 11 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1, calculates a width direction deviation of tension ΔT in the steady portion of the rolled material S (a tension difference between both width direction ends (drive side and work side ends) in the steady portion of the rolled material S) based on the width direction distribution of tension in the steady portion of the rolled material S detected by the tension detector 11 during the period from when the leading end of the rolled material S passes through the rolling mill Fn to be controlled until the tail end of the rolled material S passes through the preceding rolling mill Fn-1.

[0030] The meandering amount detection device 15 is installed between each rolling mill from the first rolling mill F1 to the last rolling mill FN (in Figure 1, only the meandering amount detection device 15 installed between the rolling mill Fn to be controlled and the rolling mill Fn-1 preceding it is shown), and is equipped with an imaging device 13 and a meandering amount calculation unit 14. A meandering amount detection device 15 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 detects a meandering amount δi of the rolling material S from when the tail end of the rolling material S passes through the preceding rolling mill Fn-1 until it passes through the meandering amount detection device 15. The imaging device 13 is composed of a line sensor camera or an area sensor camera, and captures an image of the surface of the traveling rolling material S. The meandering amount calculation unit 14 detects the positions of both ends (the driving side and working side ends) of the rolling material S in the width direction based on the captured image obtained by the imaging device 13, calculates the position of the width direction center of the rolling material S from the detected positions of both ends of the rolling material S in the width direction, and calculates the distance from the center of each of the rolling mills F1 to FN in the width direction to the calculated position of the width direction center of the rolling material S as the meandering amount δi of the rolling material S.

[0031] Further, a load detector 16 is installed on each of the rolling mills from the first rolling mill F1 to the last rolling mill FN (only the load detector 16 installed on the rolling mill Fn to be controlled is shown in FIG. 1). The load detector 16 installed on the rolling mill Fn to be controlled detects the rolling loads on the work side and drive side of the rolling mill Fn to be controlled from the time the tail end of the rolled material S passes through the previous rolling mill Fn-1 to the time it passes through the meandering amount detection device 15, and the rolling loads on the work side and drive side of the rolling mill Fn to be controlled from the time the tail end of the rolled material S passes through the meandering amount detection device 15 to the time it passes through the rolling mill Fn to be controlled.

[0032] Moreover, the differential load calculation unit 17 is connected to each load detector 16. The differential load calculation unit 17 connected to the load detector 16 installed in the rolling mill Fn to be controlled calculates a differential load ΔP, which is a difference between the rolling load on the working side and the rolling load on the driving side, based on the rolling loads on the working side and the driving side detected by the load detector 16 during the period from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 to when it passes through the meandering amount detection device 15 and during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled.

[0033] Each of the first leveling correction amount calculation unit 18, the second leveling correction amount calculation unit 19, the third leveling correction amount calculation unit 20, the meandering amount prediction model generation unit 21, the meandering amount prediction unit 22, the judgment unit 23, the leveling correction amount correction unit 24, and the leveling control unit 25 is a computer system having a calculation function, and each function of the first leveling correction amount calculation unit 18, the second leveling correction amount calculation unit 19, the third leveling correction amount calculation unit 20, the meandering amount prediction model generation unit 21, the meandering amount prediction unit 22, the judgment unit 23, the leveling correction amount correction unit 24, and the leveling control unit 25 (steps S3, S7, and S10 to S16 described later) is executed on software in accordance with instructions of various dedicated computer programs pre-stored in hardware.

[0034] The first leveling correction amount calculation unit 18 calculates the first leveling correction amount ΔLv1 at the controlled rolling mill Fn based on the widthwise deviation ΔT of the tension in the steady portion of the rolled material S calculated by the tension deviation calculation unit 12 connected to a tension detector 11 installed between the controlled rolling mill Fn and the previous rolling mill Fn-1, based on ``differential tension type meandering control'' from the time when the front end of the rolled material S passes through the controlled rolling mill Fn to the time when the tail end of the rolled material S passes through the previous rolling mill Fn-1.

[0035] Here, the first leveling correction amount ΔLv1 of the rolling mill Fn to be controlled is calculated by the following equation (1) in relation to the width direction deviation ΔT of the tension in the steady portion of the rolled material S calculated by the tension deviation calculation unit 12. ΔLv1=α×ΔT …(1) α is a control gain in meandering control using the differential tension method, and is determined in advance taking into consideration the inlet and outlet plate thickness, plate width, and steel type of the rolled material S of the rolling mill Fn to be controlled.

[0036] In addition, the second leveling correction amount calculation unit 19 calculates a second leveling correction amount ΔLv2 at the controlled rolling mill based on the meandering amount δi of the rolled material S detected by the meandering amount detection device 15 installed between the controlled rolling mill Fn and the previous rolling mill Fn-1, based on the ``meandering control using a meandering meter method'' and the ``meandering control using a differential load method'', during the period from when the tail end of the rolled material S passes through the previous rolling mill Fn-1 to when it passes through the meandering amount detection device 15 installed between the controlled rolling mill Fn and the previous rolling mill Fn-1.

[0037] Here, the second leveling correction amount ΔLv2 in the rolling mill Fn to be controlled is calculated by equation (2) in relation to the above-mentioned meandering amount δi of the rolled material S and the load difference ΔP between the work side and the drive side of the rolling mill Fn to be controlled. ΔLv2=β×ΔP / Mi+γ×δi…(2) β is the control gain in the meandering control using the differential load method, Mi is the parallel stiffness of the rolling mill Fn to be controlled, and γ is the control gain in the meandering control using the meandering gauge method. β and γ are determined in advance taking into consideration the inlet and outlet strip thickness and strip width of the rolling mill Fn to be controlled, and the steel grade of the rolled material S.

[0038] In addition, the third leveling correction amount calculation unit 20 calculates the third leveling correction amount ΔLv3 at the controlled rolling mill Fn based on the differential load ΔP between the work side and drive side of the controlled rolling mill Fn calculated by the differential load calculation unit 17 connected to the load detector 16 provided on the controlled rolling mill Fn, based on ``differential load type meandering control'' from the time the tail end of the rolled material S passes through the controlled rolling mill Fn and the previous stage rolling mill Fn-1 until it passes through the controlled rolling mill Fn.

[0039] Here, the third leveling correction amount ΔLv3 in the rolling mill Fn to be controlled is calculated by equation (3) in relation to the load difference ΔP between the work side and drive side of the rolling mill Fn to be controlled. ΔLv3=β×ΔP / Mi …(3) β is the control gain in the meandering control of the differential load method, and Mi is the parallel stiffness of the rolling mill Fn to be controlled. As described above, β is determined in advance taking into consideration the inlet and outlet thicknesses and widths of the rolling mill Fn to be controlled, and the steel grade of the rolled material S.

[0040] 4, the meandering amount prediction model generation unit 21 uses as input data information on the size of the rolled material S in the past, information on the temperature of the rolled material S in the past, information on the work rolls of the finishing rolling facility 4, information on the finish rolling tension of the rolled material S in the past, the actual first leveling correction amount at the rolling mill Fn to be controlled in the past, the actual second leveling correction amount at the rolling mill Fn to be controlled in the past, and the actual third leveling correction amount at the rolling mill to be controlled in the past as input data, and performs machine learning on a plurality of learning data in which the actual meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN in the finishing rolling facility 4 in the past for this input data is output data, thereby generating a meandering amount prediction model 210. Note that the plurality of learning data in generating the meandering amount prediction model 210, i.e., the plurality of past learning data, means data based on a plurality of results before the present.

[0041] Here, examples of "information about the size of the rolled material S" include the dimensions of the product (thickness, width, length), the dimensions of the slab extracted from the heating furnace 2 (thickness, width, length), and the camber amount at the front and rear ends of the rolled material S after rough rolling. Examples of "information about the temperature of the rolled material S" include the temperature of the slab when it is extracted from the heating furnace (average value in the sheet width direction, temperature at the center in the sheet width direction, and temperature at the ends in the sheet width direction), and the temperature of the sheet bar after rough rolling is completed (average value in the sheet width direction, temperature at the center in the sheet width direction, and temperature at the ends in the sheet width direction). Examples of "information about the work rolls of the finishing rolling facility 4" include the number of rolls after the work rolls are changed in each of F1 to FN, the type of work rolls in each of F1 to FN, the rolling tonnage after the work rolls are changed in each of F1 to FN, and the mill rigidity difference in each of F1 to FN. In addition, examples of "information regarding the finishing rolling tension of the rolled material S" include the widthwise distribution of the tension of the rolled material S detected by tension detectors 11 installed at least between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1, and between the preceding rolling mill Fn-1 and the preceding rolling mill Fn-2.

[0042] Further, the "rear stage rolling mill" for which the meandering amount of the tail end of the rolled material S is predicted means, in a case where the finishing rolling facility 4 has N (N is a natural number equal to or greater than 4) rolling mills F1 to FN, at least one of the rolling mills after the N / 2th rolling mill, counting sequentially from the front in the transport direction of the rolled material S. In this embodiment, the final rolling mill FN, which is the Nth mill from the front, is the "rear stage rolling mill" for which the meandering amount of the tail end of the rolled material S is predicted. Here, the meandering amount of the rolled material S refers to the distance from the center of the width direction of each of the rolling mills F1 to FN (the same direction as the width direction of the rolled material S) to the center of the width direction of the rolled material S. And the meandering amount of the tail end of the rolled material S refers to the distance from the center of the width direction of each of the rolling mills F1 to FN (the same direction as the width direction of the rolled material S) to the center of the width direction of the tail end of the rolled material S.

[0043] In addition, the multiple learning data read into the meandering amount prediction model generation unit 21 (information regarding the past size of the rolled material S, information regarding the past temperature of the rolled material S, information regarding the past work rolls of the finishing rolling equipment 4, information regarding the past finish rolling tension of the rolled material S, the actual first leveling correction amount at the rolling mill Fn that is the past object of control, the actual second leveling correction amount at the rolling mill Fn that is the past object of control, the actual third leveling correction amount at the rolling mill that is the past object of control, and the actual meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN in the finishing rolling equipment 4) are input to the meandering amount prediction model generation unit 21 from the upper computer 26.

[0044] In this embodiment, since a neural network is adopted as a machine learning technique, a neural network model is generated as the meandering amount prediction model 2100. That is, the meandering amount prediction model generation unit 21 creates a neural network model as the meandering amount prediction model 210 that links input actual data in the learning data (information on the size of the rolled material S in the past, information on the temperature of the rolled material S in the past, information on the work rolls of the finishing rolling facility 4 in the past, information on the finish rolling tension of the rolled material S in the past, the actual first leveling correction amount at the rolling mill Fn to be controlled in the past, the actual second leveling correction amount at the rolling mill Fn to be controlled in the past, and the actual third leveling correction amount at the rolling mill to be controlled in the past) and output actual data (the actual meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN in the finishing rolling facility 4 in the past). The neural network model is expressed, for example, by a function formula.

[0045] Further, the meandering amount prediction unit 22 inputs information on the size of the rolled material S in the current rolling pass, information on the temperature of the rolled material S in the current rolling pass, information on the work rolls of the finishing rolling equipment 4 in the current rolling pass, information on the finish rolling tension of the rolled material S in the current rolling pass, the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20 into the meandering amount prediction model 210 generated by the meandering amount prediction model generation unit 21, and performs processing to predict the meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN.

[0046] Here, among the information regarding the size of the rolled material S in the current rolling pass input to the meandering amount prediction model 210, information regarding the product dimensions (thickness, width, length) and the slab dimensions (thickness, width, length) extracted from the heating furnace 2 are input from the host computer 26 to the meandering amount prediction unit 22. In addition, among the information on the size of the rolled material S in the current rolling pass input to the meandering amount prediction model 210, the camber amount of the front and rear ends of the rolled material S after rough rolling is information on the camber amount (lateral bending amount) of the front and rear ends of the rolled material S detected by a shape detector 29 installed between the rough rolling mill 3 and the finish rolling equipment 4. The shape detector 29 is equipped with an imaging device 27 and an image processing device 28 installed between the rough rolling mill 3 and the finish rolling equipment 4. The imaging device 27 is composed of an area sensor camera, and captures an image of the surface of the running rolled material S with the area sensor camera. Then, information on the captured image captured by the area sensor camera is sent to the image processing device 28, and the image processing device 28 detects the positions of both ends of the rolled material S in the width direction from the luminance distribution in the rolling material running direction and the direction perpendicular to the rolling material S based on the captured image, and calculates the camber amount of the front and rear ends of the rolled material S based on the detected positions of both ends of the rolled material S in the width direction.

[0047] Furthermore, among the information regarding the temperature of the rolled material S in the current rolling pass input to the meandering amount prediction model 210, the temperature of the slab at the time of removal from the heating furnace (average value in the plate width direction, temperature at the center in the plate width direction, and temperature at the ends in the plate width direction) is input from the host computer 26 to the meandering amount prediction unit 22, and the temperature of the sheet bar after completion of rough rolling (average value in the plate width direction, temperature at the center in the plate width direction, and temperature at the ends in the plate width direction) is input to the meandering amount prediction unit 22 from a thermometer 30 installed on the exit side of the roughing mill 3.

[0048] Further, information regarding the work rolls of the finishing rolling equipment 4 in the current rolling pass is input from the host computer 26 to the meandering amount prediction unit 22 . In addition, information regarding the finishing rolling tension of the rolled material S in the current rolling pass is input to the meandering amount prediction unit 22 in the form of the widthwise distribution of the tension of the rolled material S detected by tension detectors 11 installed at least between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 and between the preceding rolling mill Fn-1 and the preceding rolling mill Fn-2.

[0049] FIG. 5 shows a process flow of the meandering amount prediction model 210, which is a neural network model. The meandering amount prediction model 210, which is a neural network model, is a machine learning model that predicts the meandering amount of the tail end of the rolled material S at the rear rolling mill FN in the finishing rolling equipment 4, and includes, from the input side, an input layer 211, an intermediate layer 212, and an output layer 213. The input layer 211 stores information regarding the size of the rolled material S in the current rolling pass, information regarding the temperature of the rolled material S in the current rolling pass, information regarding the work rolls of the finishing rolling equipment 4 in the current rolling pass, information regarding the finish rolling tension of the rolled material S in the current rolling pass, information regarding the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, information regarding the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and information regarding the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20.

[0050] The intermediate layer 212 is composed of multiple hidden layers, and multiple neurons are arranged in each hidden layer. The number of hidden layers configured in the intermediate layer 212 is not particularly limited, but it is preferable that the number of hidden layers is 5 or less because, empirically, if there are too many hidden layers, the prediction accuracy decreases. The output layer 213 combines the neuron information transmitted by the intermediate layer 212 and outputs the information as a predicted meandering amount of the tail end of the rolled material S at the rear rolling mill FN in the final finishing rolling equipment 4.

[0051] Further, the judgment unit 23 judges whether or not the predicted meandering amount of the tail end portion of the rolled material S in the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 is smaller than a predetermined threshold value. The predetermined threshold value is set to, for example, about 30 mm which is the average value of the difference between the width of the rolled material S and the distance in the width direction of the rolled material between a pair of side guides (not shown) installed on the inlet side of the finishing rolling equipment 4. In addition, when the judgment result of the judgment unit 23 is that the predicted meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 is equal to or greater than a predetermined threshold value, the leveling correction amount correction unit 24 corrects the first leveling correction amount ΔLv1 at the controlled rolling mill Fn calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the controlled rolling mill Fn calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 calculated by the third leveling correction amount calculation unit 20 so that the predicted meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 becomes smaller than the aforementioned predetermined threshold value.

[0052] Specifically, when the above-mentioned predicted meandering amount is equal to or greater than a predetermined threshold, the leveling correction amount corrector 24 corrects the control gain α in the first leveling correction amount ΔLv1=α×ΔT to calculate a first leveling correction correction amount ΔLv1', corrects the control gains β and γ in the second leveling correction amount ΔLv2=β×ΔP / Mi+γ×δi to calculate a second leveling correction correction amount ΔLv2', and corrects the control gain β in the third leveling correction amount ΔLv3=β×ΔP / Mi to calculate a third leveling correction correction amount ΔLv3'.

[0053] In addition, when the judgment result of the judgment unit 23 indicates that the predicted meandering amount of the tail end of the rolled material S at the rear-stage rolling mill FN predicted by the meandering amount prediction unit 22 is smaller than the above-mentioned predetermined threshold value, as shown in FIG. 6, in the rolling mill Fn to be controlled, in the first control section A from when the front end of the rolled material S passes through the rolling mill Fn to be controlled to when the tail end of the rolled material S passes through the front-stage rolling mill Fn-1, the leveling control unit 25 calculates the leveling correction of the first leveling correction amount ΔLv1 calculated by the first leveling correction amount calculation unit 18 in the second control section A from when the tail end of the rolled material S passes through the front-stage rolling mill Fn-1 to when it passes through the meandering amount detection device 15. The leveling control is performed by controlling the leveling device 7 provided in the rolling mill Fn to be controlled so that in a third control section C from when the tail end of the rolled material passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled, a leveling correction is performed by adding a second leveling correction amount ΔLv2 calculated by the second leveling correction amount calculation unit 19 to the first leveling correction amount ΔLv1, and a third leveling correction amount ΔLv3 calculated by the third leveling correction amount calculation unit 20 to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2.

[0054] That is, when the judgment result of the judgment unit 23 indicates that the predicted meandering amount of the tail end of the rolling material S in the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 is smaller than the above-mentioned predetermined threshold value, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the first leveling correction amount ΔLv1 calculated by the first leveling correction amount calculation unit 18 to the leveling amount (lock-on value) LvL previously set by the setup calculation in the first control section A. Also, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the leveling correction amount obtained by adding the first leveling correction amount ΔLv1 to the second leveling correction amount ΔLv2 calculated by the second leveling correction amount calculation unit 19 to the leveling amount (lock-on value) LvL previously set by the setup calculation in the second control section B. Furthermore, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding a leveling correction amount obtained by adding a third leveling correction amount ΔLv3 calculated by the third leveling correction amount calculation unit 20 to the leveling amount (lock-on value) LvL previously set by the setup calculation in the third control section C, and the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2.

[0055] Here, the leveling amount (lock-on value) LvL previously set in the setup calculation is set to a value that maximizes the wobbling effect among the median values ​​of the wedge variations previously evaluated. The tracking information of the rolled material S is sent to the leveling control unit 25, and the leveling control unit 25 constantly grasps the position of the tail end of the rolled material S. Then, the leveling control unit 25 performs leveling control of the controlled rolling mill Fn with a leveling amount LvL set in advance by a setup calculation until the front end of the rolled material S passes through the controlled rolling mill Fn, performs leveling control of the controlled rolling mill Fn as described above from when the front end of the rolled material S passes through the controlled rolling mill Fn until the tail end of the rolled material S passes through the controlled rolling mill Fn, and performs leveling control of the controlled rolling mill Fn with the leveling amount LvL at which the tail end of the rolled material S passes through the controlled rolling mill Fn.

[0056] Furthermore, when the leveling control unit 25 corrects the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20, the leveling correction amount correction unit 24 corrects the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20, In the above-mentioned first control section A, no leveling correction is performed for the first leveling correction amount ΔLv1, no leveling correction is performed for the leveling correction amount obtained by adding the second leveling correction amount ΔLv2 to the first leveling correction amount ΔLv1 in the second control section B, and no leveling correction is performed for the leveling correction amount obtained by adding the third leveling correction amount ΔLv3 to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 in the third control section C. Instead, the leveling control unit 25 controls the leveling device 7 provided in the rolling mill Fn to be controlled so as to perform leveling control in the rolling mill Fn to be controlled, so as to perform leveling correction of the first leveling correction correction amount ΔLv1′ corrected by the leveling correction amount correcting unit 24 in the first control section A described above, leveling correction of the leveling correction amount obtained by adding the second leveling correction correction amount ΔLv2′ corrected by the leveling correction amount correcting unit 24 to the first leveling correction correction amount ΔLv1′ in the second control section B, and leveling correction of the leveling correction amount obtained by adding the third leveling correction correction amount ΔLv3′ corrected by the leveling correction amount correcting unit 24 to the first leveling correction correction amount ΔLv1′ and the second leveling correction correction amount ΔLv2′ in the third control section C.

[0057] In other words, in the leveling correction amount correction unit 24, when the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20 are corrected, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the first leveling correction amount ΔLv1' to the leveling amount (lock-on value) LvL set in advance by setup calculation in the first control section A. Moreover, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding a leveling correction amount obtained by adding a first leveling correction correction amount ΔLv1' and a second leveling correction correction amount ΔLv2' to a leveling amount (lock-on value) LvL previously set by a setup calculation in the second control section B. Furthermore, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding a leveling correction amount obtained by adding a first leveling correction correction amount ΔLv1' and a second leveling correction correction amount ΔLv2' and a third leveling correction correction amount ΔLv3' to a leveling amount (lock-on value) LvL previously set by a setup calculation in the third control section C.

[0058] In addition, in Figure 6, examples are shown in which the roll gap is tightened on the work (OP) side for each of the first leveling correction amount ΔLv1, the second leveling correction amount ΔLv2, the third leveling correction amount ΔLv3, the first leveling correction correction amount ΔLv1', the second leveling correction correction amount ΔLv2', and the third leveling correction correction amount ΔLv3'. Next, the flow of processing by the leveling control device 10 will be described with reference to the flowcharts shown in FIGS.

[0059] First, in step S1, a tension detector 11 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 detects the widthwise distribution of tension in the steady portion of the running rolled material S from when the leading end of the rolling material S passes through the rolling mill Fn to be controlled until the tail end of the rolling material S passes through the preceding rolling mill Fn-1 (tension widthwise distribution detection step). Next, in step S2, a tension deviation calculation unit 12 connected to a tension detector 11 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 calculates a widthwise deviation ΔT of the tension in the steady portion of the rolled material S based on the widthwise distribution of tension in the steady portion of the rolled material S detected by the tension detector 11 in step S1 from the time when the leading end of the rolled material S passes through the rolling mill Fn to be controlled until the tail end of the rolled material S passes through the preceding rolling mill Fn-1 (tension widthwise deviation calculation step).

[0060] Next, in step S3, the first leveling correction amount calculation unit 18 calculates a first leveling correction amount ΔLv1 at the controlled rolling mill Fn based on the width-wise deviation ΔT of the tension in the steady portion of the rolled material S calculated in step S2 by the tension deviation calculation unit 12 connected to the tension detector 11 installed between the controlled rolling mill Fn and the preceding rolling mill Fn-1, from the time when the front end of the rolled material S passes through the controlled rolling mill Fn to the time when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 (first leveling correction amount calculation step).

[0061] Here, the first leveling correction amount ΔLv1 in the rolling mill Fn to be controlled is calculated by the above-mentioned formula (1). Next, in step S4, the meandering amount detection device 15 installed between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1 detects the meandering amount δi of the rolled material S from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 until it passes through the meandering amount detection device 15 (meandering amount detection step). Next, in step S5, the load detector 16 installed in the rolling mill Fn to be controlled detects the rolling load on the working side and driving side of the rolling mill Fn to be controlled from the time when the tail end of the rolled material S passes through the previous rolling mill Fn-1 to the time when it passes through the meandering amount detection device 15 (rolling load detection step).

[0062] Next, in step S6, the differential load calculation unit 17 connected to the load detector 16 installed in the rolling mill Fn to be controlled calculates the differential load ΔP, which is the difference between the rolling load on the working side and the rolling load on the driving side, based on the rolling loads on the working side and the driving side detected by the load detector 16 in step S5 during the period from when the tail end of the rolled material S passes through the previous rolling mill Fn-1 to when it passes through the meandering amount detection device 15 (differential load detection step).

[0063] Next, in step S7, the second leveling correction amount calculation unit 19 calculates a second leveling correction amount ΔLv2 at the controlled rolling mill based on the meandering amount δi of the rolled material S detected by the meandering amount detection device 15 installed between the controlled rolling mill Fn and the preceding rolling mill Fn-1 in step S4 from the time when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 until it passes through the meandering amount detection device 15 installed between the controlled rolling mill Fn and the preceding rolling mill Fn-1, and the differential load ΔP between the work side and the drive side of the controlled rolling mill Fn calculated by the differential load calculation unit 17 connected to the load detector 16 provided in the controlled rolling mill Fn in step S6 (second leveling correction amount calculation step).

[0064] Here, the second leveling correction amount ΔLv2 in the rolling mill Fn to be controlled is calculated by the above-mentioned formula (2). Next, in step S8, the load detector 16 installed in the rolling mill Fn to be controlled detects the rolling load on the work side and drive side of the rolling mill Fn to be controlled from the time when the tail end of the rolled material S passes through the meandering amount detection device 15 to the time when it passes through the rolling mill Fn to be controlled (rolling load detection step).

[0065] Next, in step S9, the differential load calculation unit 17 connected to the load detector 16 installed in the rolling mill Fn to be controlled calculates the differential load ΔP, which is the difference between the rolling load on the working side and the rolling load on the driving side, based on the rolling loads on the working side and the driving side detected by the load detector 16 in step S8 during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled (differential load detection step). Next, in step S10, the third leveling correction amount calculation unit 20 calculates the third leveling correction amount ΔLv3 at the controlled rolling mill Fn based on the differential load ΔP between the work side and drive side of the controlled rolling mill Fn calculated by the differential load calculation unit 17 connected to the load detector 16 provided on the controlled rolling mill Fn in step S9, during the period from when the tail end of the rolled material S passes through the controlled rolling mill Fn and the preceding rolling mill Fn-1 until it passes through the controlled rolling mill Fn (third leveling correction amount calculation step).

[0066] Here, the third leveling correction amount ΔLv3 in the rolling mill Fn to be controlled is calculated by the above-mentioned formula (3). Next, in step S11, the meandering amount prediction model generation unit 21 uses information on the size of the rolled material S in the past, information on the temperature of the rolled material S in the past, information on the work roll of the finishing rolling facility 4 in the past, information on the finish rolling tension of the rolled material S in the past, the actual first leveling correction amount in the rolling mill Fn to be controlled in the past, the actual second leveling correction amount in the rolling mill Fn to be controlled in the past, and the actual third leveling correction amount in the rolling mill to be controlled in the past as input data, and generates a meandering amount prediction model 210 by machine learning a plurality of learning data in which the actual meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN in the finishing rolling facility 4 in the past for this input data is output data (meandering amount prediction model generation step). Note that the plurality of learning data in the generation of this meandering amount prediction model 210, i.e., the plurality of past learning data, means data based on a plurality of actual results before the present, as described above.

[0067] Here, as described above, examples of the "information on the size of the rolled material S" include the dimensions (thickness, width, length) of the product, the dimensions (thickness, width, length) of the slab extracted from the heating furnace 2, and the camber amount at the front and rear ends of the rolled material S after rough rolling. In addition, examples of the "information on the temperature of the rolled material S" include the temperature of the slab when it is extracted from the heating furnace (average value in the sheet width direction, temperature at the center in the sheet width direction, temperature at the ends in the sheet width direction), and the temperature of the sheet bar after rough rolling is completed (average value in the sheet width direction, temperature at the center in the sheet width direction, temperature at the ends in the sheet width direction). In addition, examples of the "information on the work rolls of the finishing rolling facility 4" include the number of rolls after the work rolls are changed in each of F1 to FN, the type of work rolls in each of F1 to FN, the rolling tonnage after the work rolls are changed in each of F1 to FN, and the mill rigidity difference in each of F1 to FN. In addition, examples of "information regarding the finishing rolling tension of the rolled material S" include the widthwise distribution of the tension of the rolled material S detected by tension detectors 11 installed at least between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1, and between the preceding rolling mill Fn-1 and the preceding rolling mill Fn-2.

[0068] Furthermore, as described above, the "rear stage rolling mill" for which the meandering amount of the tail end of the rolled material S is predicted means, in a case where the finishing rolling facility 4 has N (N is a natural number equal to or greater than 4) rolling mills F1 to FN, at least one of the rolling mills after the N / 2th rolling mill, counting sequentially from the front in the transport direction of the rolled material S. In this embodiment, the final rolling mill FN, which is the Nth from the front, is the "rear stage rolling mill" for which the meandering amount of the tail end of the rolled material S is predicted.

[0069] In addition, the multiple learning data read into the meandering amount prediction model generation unit 21 (information regarding the past size of the rolled material S, information regarding the past temperature of the rolled material S, information regarding the past work rolls of the finishing rolling equipment 4, information regarding the past finish rolling tension of the rolled material S, the actual first leveling correction amount at the rolling mill Fn that is the past object of control, the actual second leveling correction amount at the rolling mill Fn that is the past object of control, the actual third leveling correction amount at the rolling mill that is the past object of control, and the actual meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN in the finishing rolling equipment 4) are input into the meandering amount prediction model generation unit 21 from the host computer 26, as described above.

[0070] Next, in step S12, the meandering amount prediction unit 22 inputs information on the size of the rolled material S in the current rolling pass, information on the temperature of the rolled material S in the current rolling pass, information on the work rolls of the finishing rolling equipment 4 in the current rolling pass, information on the finish rolling tension of the rolled material S in the current rolling pass, the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20 into the meandering amount prediction model 210 generated in step S11, and performs a process of predicting the meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN (meandering amount prediction step).

[0071] Here, among the information regarding the size of the rolled material S in the current rolling pass input to the meandering amount prediction model 210, information regarding the product dimensions (thickness, width, length) and the slab dimensions (thickness, width, length) extracted from the heating furnace 2 are input from the host computer 26 to the meandering amount prediction unit 22, as described above. In addition, among the information regarding the size of the rolled material S in the current rolling pass input to the meandering amount prediction model 210, the camber amount at the front and rear ends of the rolled material S after rough rolling is, as described above, information on the camber amount (amount of lateral bending) at the front and rear ends of the rolled material S detected by the shape detector 29 installed between the roughing rolling mill 3 and the finishing rolling equipment 4 is input.

[0072] Furthermore, among the information regarding the temperature of the rolled material S in the current rolling pass that is input to the meandering amount prediction model 210, the temperature of the slab at the time of removal from the heating furnace (average value in the plate width direction, temperature at the center in the plate width direction, and temperature at the ends in the plate width direction) is input from the host computer 26 to the meandering amount prediction unit 22, as described above, and the temperature of the sheet bar after completion of rough rolling (average value in the plate width direction, temperature at the center in the plate width direction, and temperature at the ends in the plate width direction) is input to the meandering amount prediction unit 22 from the thermometer 30 installed on the exit side of the roughing mill 3.

[0073] Moreover, information regarding the work rolls of the finishing rolling equipment 4 in the current rolling pass is input from the host computer 26 to the meandering amount prediction unit 22, as described above. As described above, information regarding the finishing rolling tension of the rolled material S in the current rolling pass is input to the meandering amount prediction unit 22 in the form of the widthwise distribution of the tension of the rolled material S detected by the tension detector 11 installed at least between the rolling mill Fn to be controlled and the preceding rolling mill Fn-1, and between the preceding rolling mill Fn-1 and the preceding rolling mill Fn-2.

[0074] Next, in step S13, the judgment unit 23 judges whether or not the predicted meandering amount of the tail end portion of the rolled material S in the rear-stage rolling mill FN predicted in step S12 is smaller than a predetermined threshold value (judgment step). As described above, the predetermined threshold value is set to, for example, about 30 mm, which is the average value of the difference between the width of the rolled material S and the distance in the width direction of the rolled material between a pair of side guides (not shown) installed on the inlet side of the finishing rolling equipment 4. If the determination result in step S13 is YES, the process proceeds to step S14, and if the determination result in step S13 is NO, the process proceeds to step S15.

[0075] In step S14, the leveling control unit 25 determines that the judgment result in the judgment unit 23 is that the predicted meandering amount of the tail end of the rolled material S at the rear-stage rolling mill FN predicted by the meandering amount prediction unit 22 is smaller than the above-mentioned predetermined threshold value, and performs leveling correction of the first leveling correction amount ΔLv1 in the first control section A from when the front end of the rolled material S passes through the controlled rolling mill Fn to when the tail end of the rolled material S passes through the front-stage rolling mill Fn-1, and performs leveling correction of the first leveling correction amount ΔLv1 in the second control section B from when the tail end of the rolled material S passes through the front-stage rolling mill Fn-1 to when it passes through the meandering amount detection device 15. The leveling device 7 provided in the rolling mill Fn to be controlled is controlled to perform leveling control by performing a leveling correction of a leveling correction amount obtained by adding the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 to the third leveling correction amount ΔLv3 in a third control section C from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled (leveling control step).

[0076] That is, in step S14, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the first leveling correction amount ΔLv1 calculated in step S3 to the leveling amount (lock-on value) LvL previously set by the setup calculation in the first control section A, assuming that the predicted meandering amount of the tail end of the rolling material S in the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 is smaller than the above-mentioned predetermined threshold value. Also, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the leveling correction amount obtained by adding the first leveling correction amount ΔLv1 to the second leveling correction amount ΔLv2 calculated in step S7 to the leveling amount (lock-on value) LvL previously set by the setup calculation in the second control section B. Furthermore, in the third control section C, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding a leveling correction amount obtained by adding a third leveling correction amount ΔLv3 calculated in step S10 to the leveling amount (lock-on value) LvL previously set by the setup calculation to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2.

[0077] On the other hand, in step S15, the leveling correction amount correction unit 24 determines that the judgment result in the judgment unit 23 is that the predicted meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 is equal to or greater than a predetermined threshold, and corrects the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated in step S3, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated in step S7, and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated in step S10 so that the predicted meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN predicted in step S12 is smaller than the aforementioned predetermined threshold (leveling correction amount correction step).

[0078] Specifically, when the above-mentioned predicted meandering amount is equal to or greater than a predetermined threshold, the leveling correction amount corrector 24 corrects the control gain α in the first leveling correction amount ΔLv1=α×ΔT to calculate a first leveling correction correction amount ΔLv1', corrects the control gains β and γ in the second leveling correction amount ΔLv2=β×ΔP / Mi+γ×δi to calculate a second leveling correction correction amount ΔLv2', and corrects the control gain β in the third leveling correction amount ΔLv3=β×ΔP / Mi to calculate a third leveling correction correction amount ΔLv3'.

[0079] Then, in step S16, since the leveling control unit 25 corrected the first leveling correction amount ΔLv1, the second leveling correction amount ΔLv2, and the third leveling correction amount in step S15, it does not perform leveling correction of the first leveling correction amount ΔLv1 in the first control section A, does not perform leveling correction of the leveling correction amount obtained by adding the second leveling correction amount ΔLv2 to the first leveling correction amount ΔLv1 in the second control section B, and does not perform leveling correction of the leveling correction amount obtained by adding the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 to the third leveling correction amount ΔLv3 in the third control section C. Instead, in step S16, the leveling control unit 25 controls the leveling device 7 provided in the rolling mill Fn to be controlled so as to perform leveling control in the rolling mill Fn to be controlled, so as to perform leveling correction of the first leveling correction correction amount ΔLv1′ corrected by the leveling correction amount correcting unit 24 in the first control section A described above, leveling correction of the leveling correction amount obtained by adding the second leveling correction correction amount ΔLv2′ corrected by the leveling correction amount correcting unit 24 to the first leveling correction correction amount ΔLv1′ in the second control section B, and leveling correction of the leveling correction amount obtained by adding the third leveling correction correction amount ΔLv3′ corrected by the leveling correction amount correcting unit 24 to the first leveling correction correction amount ΔLv1′ and the second leveling correction correction amount ΔLv2′ in the third control section C (leveling control step).

[0080] That is, in step S16, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the first leveling correction correction amount ΔLv1' to the leveling amount (lock-on value) LvL previously set by the setup calculation in the first control section A. Also, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the leveling correction amount obtained by adding the first leveling correction correction amount ΔLv1' to the second leveling correction correction amount ΔLv2' to the leveling amount (lock-on value) LvL previously set by the setup calculation in the second control section B. Furthermore, the leveling control unit 25 performs leveling control of the rolling mill Fn to be controlled with a corrected leveling Lv obtained by adding the leveling amount (lock-on value) LvL previously set by setup calculation in the third control section C to the leveling correction amount obtained by adding the first leveling correction correction amount ΔLv1', the second leveling correction correction amount ΔLv2' and the third leveling correction correction amount ΔLv3'.

[0081] This ends the processing by the leveling control device 10. In this way, according to the leveling control device 10 and the leveling control method of this embodiment, the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled is calculated based on the width direction deviation ΔT of the tension in the steady portion of the rolled material S calculated from the width direction distribution of the tension in the steady portion of the rolled material S detected by the tension detector 11 installed between the rolling mill Fn-1 of the previous stage and the rolling mill Fn to be controlled, during the period from when the front end of the rolled material S passes through the rolling mill Fn to be controlled until the tail end of the rolled material S passes through the rolling mill Fn-1 of the previous stage with respect to the rolling mill Fn to be controlled. a corrective amount calculation unit 18 (first leveling correction step: step S3); and a second leveling correction amount calculation unit 19 (second leveling correction amount calculation step: step S7) that calculates a second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled based on the meandering amount δi of the rolling material S detected by the meandering amount detection device 15 during the period from when the tail end of the rolling material S passes through the preceding rolling mill Fn-1 until when it passes through the meandering amount detection device 15 and the differential load ΔP calculated from the rolling loads on the working side and the driving side of the rolling mill Fn to be controlled detected by the load detector 16 provided in the rolling mill Fn to be controlled; A third leveling correction amount calculation unit 20 (third leveling correction amount calculation step: step S10) calculates a third leveling correction amount ΔLv3 at the rolling mill to be controlled based on a differential load ΔP calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, which is detected by a load detector 16, during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill to be controlled; A leveling correction of ΔLv1 is performed by adding the first leveling correction amount ΔLv1 to the second leveling correction amount ΔLv2 in a second control section B from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 to when it passes through the meandering amount detection device 15, and a leveling correction of the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 to the third leveling correction amount ΔLv3 is performed in a third control section C from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled.and a leveling control unit 25 (leveling control step: step S14) that controls the leveling of the rolling mill Fn to be controlled.

[0082] As a result, meandering control by the differential tension method is performed in the steady portion of the rolled material S from when the front end of the rolled material S passes through the rolling mill Fn to be controlled to when the tail end of the rolled material S passes through the rolling mill Fn-1 preceding the rolling mill Fn to be controlled, eliminating the cause of meandering before it becomes apparent, and it is possible to prevent meandering of the rolled material S in advance. Then, from when the tail end of the rolled material S passes through the rolling mill Fn-1 preceding the rolling mill Fn to be controlled to when it passes through the meander amount detection device 15, meandering control by the meander meter method and meandering control by the differential load method are used in combination to control meandering that occurs because the meandering cause cannot be completely eliminated by the control by the differential tension method, and after the tail end of the rolled material S passes through the meander amount detection device 15, meandering control by the differential load method is performed to stabilize the threading and reduce the amount of meandering.

[0083] In addition, according to the leveling control device 10 and the leveling control method of this embodiment, there is provided a meandering amount prediction model generation unit 21 (meandering amount prediction model generation step: step S11) that uses as input data information on the past size of the rolled material S, information on the past temperature of the rolled material S, information on the past finish rolling tension of the rolled material S, information on the past work rolls of the finishing rolling equipment 4, the past actual first leveling correction amount at the rolling mill Fn to be controlled, the past actual second leveling correction amount at the rolling mill Fn to be controlled, and the past actual third leveling correction amount at the rolling mill Fn to be controlled, and uses as output data the past actual meandering amount of the tail end of the rolled material S at the rear rolling mill FN in the finishing rolling equipment 4 for this input data as machine learning to generate a meandering amount prediction model 210.

[0084] In addition, according to the leveling control device 10 and the leveling control method of this embodiment, the meandering amount prediction model 210 includes information on the size of the rolled material S in the current rolling pass, information on the temperature of the rolled material S in the current rolling pass, information on the finish rolling tension of the rolled material S in the current rolling pass, information on the work rolls of the finish rolling equipment 4 in the current rolling pass, the first leveling correction amount in the rolling mill Fn to be controlled calculated by the first leveling correction amount calculation unit 18 (first leveling correction amount calculation step: step S3), and The system is equipped with a meandering amount prediction unit 22 (wandering amount prediction step: step S12) that predicts the meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN by inputting the tailing correction amount ΔLv1, the second leveling correction amount ΔLv2 at the rolling mill Fn to be controlled calculated by the second leveling correction amount calculation unit 19 (second leveling correction amount calculation: step S7), and the third leveling correction amount ΔLv3 at the rolling mill Fn to be controlled calculated by the third leveling correction amount calculation unit 20 (third leveling correction amount calculation step: step S10).

[0085] As a result, in the rolling mill Fn to be controlled, in the first control section A from when the leading end of the rolled material S passes through the rolling mill Fn to be controlled until the tail end of the rolled material S passes through the preceding rolling mill Fn-1, the first leveling correction amount ΔLv1 is applied as the leveling correction, and in the second control section B from when the tail end of the rolled material S passes through the preceding rolling mill Fn-1 until it passes through the meandering amount detection device 15, the second leveling correction amount ΔLv1 is applied as the first leveling correction amount ΔLv1. The amount of meandering of the tail end of the rolled material S at the rear stage rolling mill FN can be predicted when leveling correction by adding a third leveling correction amount ΔLv3 to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 is performed in the third control section C from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the rolling mill Fn to be controlled.

[0086] In addition, the leveling control device 10 and the leveling control method according to this embodiment are provided with a judgment unit 23 (judgment step: step S13) that judges whether the predicted meandering amount of the tail end of the rolled material S at the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 (meandering amount prediction step: step S12) is smaller than a predetermined threshold value.

[0087] According to the leveling control device 10 and the leveling control method of the present embodiment, when the judgment result of the judgment unit 23 (judgment step: step S13) is that the predicted meandering amount of the tail end of the rolled material S at the rear-stage rolling mill FN predicted by the meandering amount prediction unit 22 (meandering amount prediction step: step S12) is equal to or greater than a predetermined threshold value, the first leveling correction amount calculation unit 18 (first leveling correction amount calculation unit 21) calculates a meandering amount of the tail end of the rolled material S at the rear-stage rolling mill FN predicted by the meandering amount prediction unit 22 (meandering amount prediction step: step S12) so that the predicted meandering amount of the tail end of the rolled material S at the rear-stage rolling mill FN is smaller than the predetermined threshold value. The control unit 20 includes a leveling correction amount correcting unit 24 (leveling correction amount correcting step: step S15) that corrects the first leveling correction amount ΔLv1 at the rolling mill Fn to be controlled calculated in the second leveling correction amount calculating unit 19 (second leveling correction amount calculating step: step S7), and the third leveling correction amount ΔLv3 calculated in the third leveling correction amount calculating unit 20 (third leveling correction amount calculating step: step S10).

[0088] As a result, when the predicted meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN is greater than or equal to a predetermined threshold value, the calculated first leveling correction amount ΔLv1, second leveling correction amount ΔLv2, and third leveling correction amount ΔLv3 can be corrected so that the predicted meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN becomes smaller than the predetermined threshold value.

[0089] Moreover, according to the leveling control device 10 and the leveling control method of this embodiment, when the judgment result of the judgment unit 23 (judgment step: step S13) is that the predicted meandering amount of the tail end of the rolled material S in the rear stage rolling mill FN predicted by the meandering amount prediction unit 22 (meandering amount prediction step: step S12) is smaller than a predetermined threshold value, in the first control section A, the leveling correction of the first leveling correction amount ΔLv1 calculated by the first leveling correction amount calculation unit 18 (first leveling correction amount calculation step: step S3) is calculated as the second control correction amount ΔLv1. The leveling of the controlled rolling mill Fn is controlled so that in section B, a leveling correction is performed by adding the second leveling correction amount ΔLv2 calculated in the second leveling correction amount calculation unit 19 (second leveling correction amount calculation step: step S7) to the first leveling correction amount ΔLv1, and in the third control section C, a leveling correction is performed by adding the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 to the third leveling correction amount calculation unit 20 (third leveling correction amount calculation step: step S10).

[0090] On the other hand, when the leveling control unit 25 (leveling control step: step S16) corrects the first leveling correction amount ΔLv1, the second leveling correction amount ΔLv2, and the third leveling correction amount ΔLv3 in the leveling correction amount correction unit 24 (leveling correction amount correction step: step S15), instead of the leveling correction of the first leveling correction amount ΔLv1 in the first control section A, the leveling correction of the leveling correction amount obtained by adding the second leveling correction amount ΔLv2 to the first leveling correction amount ΔLv1 in the second control section B, and the leveling correction of the leveling correction amount obtained by adding the third leveling correction amount ΔLv3 to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2 in the third control section C, The leveling of the rolling mill Fn to be controlled is controlled so that, in the second control section B, leveling correction of the first leveling correction correction amount ΔLv1' corrected by the leveling correction amount correction unit 24 (leveling correction amount correction step: step S15) is performed, in the second control section B, leveling correction of the leveling correction amount obtained by adding the second leveling correction correction amount ΔLv2' corrected by the leveling correction amount correction unit 24 (leveling correction amount correction step: step S15) to the first leveling correction correction amount ΔLv1', and in the third control section C, leveling correction of the leveling correction amount obtained by adding the first leveling correction correction amount ΔLv1' and the second leveling correction correction amount ΔLv2' to the leveling correction amount correction unit 24 (leveling correction amount correction step: step S15).

[0091] This makes it possible to appropriately adjust the leveling correction amounts in the first control section A, the second control section B, and the third control section C for the rolling mill Fn to be controlled, and reliably suppress the amount of meandering of the tail end of the rolled material S in the rear stage rolling mill FN to within a predetermined threshold value. The manufacturing method of the hot rolled steel strip according to the present embodiment includes a finish rolling process in which the meandering of the rolled material S is controlled using the above-mentioned leveling control method to finish roll the rolled material S, a cooling process in which the rolled material S that has been finish rolled into a hot rolled steel strip is cooled by a run-out table (cooling equipment), and a winding process in which the cooled hot rolled steel strip is wound into a coil shape by a winder. This makes it possible to reduce the amount of meandering of the rolled material S that is finish rolled, and improve the productivity and yield in the hot rolling of the hot rolled steel strip.

[0092] Although the embodiment of the present invention has been described above, the present invention is not limited to this and various modifications and improvements can be made. For example, in the leveling control device 10 and the leveling control method according to the present embodiment, the meandering amount prediction model generating unit 21 (meandering amount prediction model generating step: step S11), the meandering amount predicting unit 22 (meandering amount predicting step: step S12), the determining unit 23 (determining step: step S13), and the leveling correction amount correcting unit 24 (leveling correction amount correcting step: step S15) are omitted, and prediction, determination, and correction of the meandering amount are not performed, and the leveling control unit 25 (leveling control step: step S14) uses the first leveling correction amount calculated by the first leveling correction amount calculating unit 18 (first leveling correction amount calculating step: step S3) in the first control section A. The leveling of the rolling mill Fn to be controlled may be controlled so that, in the second control section B, a leveling correction of the first leveling correction amount ΔLv1 is performed by adding the second leveling correction amount ΔLv2 calculated in the second leveling correction amount calculation unit 19 (second leveling correction amount calculation step: step S7) to the first leveling correction amount ΔLv1, and, in the third control section C, a leveling correction of the third leveling correction amount ΔLv3 calculated in the third leveling correction amount calculation unit 20 (third leveling correction amount calculation step: step S10) to the first leveling correction amount ΔLv1 and the second leveling correction amount ΔLv2.

[0093] Furthermore, the rolling mill Fn to be controlled is not limited to the n-th rolling mill Fn from the top, but may be any one or more of a plurality of (N) rolling mills. In addition, the "rear stage rolling mill" for which the amount of meandering of the tail end of the rolled material S is predicted means at least one of the rolling mills after the N / 2th rolling mill, counting sequentially from the front in the transport direction of the rolled material S, when the finishing rolling equipment 4 has N (N is a natural number greater than or equal to 4) rolling mills F1 to FN, and is not limited to the case where the "rear stage rolling mill" for which the amount of meandering of the tail end of the rolled material S is predicted is the Nth and final rolling mill FN from the front.

[0094] Furthermore, in the leveling control device 10 and the leveling control method according to this embodiment, the machine learning technique is a neural network, and the meandering amount prediction model 210 is a prediction model constructed by a neural network, but any machine learning method may be used, for example, a decision tree. EXAMPLES

[0095] 1, in a finishing rolling facility 4 equipped with seven (N=7) rolling mills F1 to F7, to verify the effect of the leveling control method according to the present invention, the amount of meandering at the rear-stage rolling mill F7 was measured in each of Comparative Example 1, Comparative Example 2, Inventive Example 1, and Inventive Example 2. In each of Comparative Example 1, Comparative Example 2, Inventive Example 1, and Inventive Example 2, the rolling mill Fn to be controlled is F7, which is the same as the rear-stage rolling mill F7.

[0096] In comparative example 1, from the time when the front end of the rolled material S passes through the controlled rolling mill F7 to the time when the tail end of the rolled material S passes through the upstream rolling mill F6, the first leveling correction amount ΔLv1 at the controlled rolling mill F7 is not calculated based on the widthwise deviation ΔT of the tension in the steady portion of the rolled material S calculated from the widthwise distribution of the tension in the steady portion of the rolled material S detected by the tension detector 11 installed between the upstream rolling mill F6 and the controlled rolling mill F7, and in the first control section A, leveling correction is not performed, and the leveling of the controlled rolling mill F7 is controlled by a predetermined leveling amount. Then, during the period from when the tail end of the rolled material S passes through the upstream rolling mill F6 to when it passes through the meandering amount detection device 15 installed between the upstream rolling mill F6 and the controlled rolling mill F7, a second leveling correction amount ΔLv2 at the controlled rolling mill F7 is calculated based on the meandering amount δi of the rolled material S detected by the meandering amount detection device 15 and the differential load ΔP calculated from the rolling loads on the working side and drive side of the controlled rolling mill F7 detected by the load detector 16 provided on the controlled rolling mill F7, and leveling of the controlled rolling mill F7 is controlled so as to perform leveling correction of the calculated second leveling correction amount ΔLv2 in the second control section B. Furthermore, during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the controlled rolling mill F7, a third leveling correction amount ΔLv3 at the controlled rolling mill F7 is calculated based on the differential load ΔP calculated from the rolling loads on the work side and drive side of the controlled rolling mill F7 detected by the load detector 16, and in the third control section C, the leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction by adding the calculated third leveling correction amount ΔLv3 to the held second leveling correction amount ΔLv2.

[0097] In addition, in comparative example 2, from the time when the front end of the rolled material S passes through the controlled rolling mill F7 to the time when the tail end of the rolled material S passes through the upstream rolling mill F6, a first leveling correction amount ΔLv1 at the controlled rolling mill F7 is calculated based on the widthwise deviation ΔT of the tension in the steady portion of the rolled material S calculated from the widthwise distribution of the tension in the steady portion of the rolled material S detected by a tension detector 11 installed between the upstream rolling mill F6 and the controlled rolling mill F7, and leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction of the first leveling correction amount ΔLv1 in the first control section A. Then, during the period from when the tail end of the rolled material S passes through the preceding rolling mill F6 to when it passes through the meandering amount detection device 15 installed between the preceding rolling mill F6 and the controlled rolling mill F7, the second leveling correction amount ΔLv2 at the controlled rolling mill F7 is not calculated based on the meandering amount δi of the rolled material S detected by the meandering amount detection device 15 and the differential load ΔP calculated from the rolling loads on the working side and driving side of the controlled rolling mill F7 detected by the load detector 16 provided in the controlled rolling mill F7, and the leveling of the controlled rolling mill F7 is controlled so as to perform the leveling correction of the held first leveling correction amount ΔLv1 in the second control section B. The leveling of the controlled rolling mill F7 was controlled. Furthermore, during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the controlled rolling mill F7, the leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction of the held first leveling correction amount ΔLv1 in the third control section C without calculating the third leveling correction amount ΔLv3 at the controlled rolling mill F7 based on the differential load ΔP calculated from the rolling loads on the work side and drive side of the controlled rolling mill F7 detected by the load detector 16.

[0098] In addition, in Example 1 of the present invention, from the time when the front end of the rolled material S passes through the controlled rolling mill F7 to the time when the tail end of the rolled material S passes through the upstream rolling mill F6, a first leveling correction amount ΔLv1 at the controlled rolling mill Fn is calculated based on the widthwise deviation ΔT of the tension in the steady portion of the rolled material S calculated from the widthwise distribution of the tension in the steady portion of the rolled material S detected by a tension detector 11 installed between the upstream rolling mill F6 and the controlled rolling mill F7, and leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction of the first leveling correction amount ΔLv1 in the first control section A. Then, during the period from when the tail end of the rolled material S passes through the upstream rolling mill F6 to when it passes through the meandering amount detection device 15 installed between the upstream rolling mill F6 and the controlled rolling mill F7, a second leveling correction amount ΔLv2 at the controlled rolling mill F7 is calculated based on the meandering amount δi of the rolled material S detected by the meandering amount detection device 15 and the differential load ΔP calculated from the rolling loads on the working side and driving side of the controlled rolling mill F7 detected by the load detector 16 provided in the controlled rolling mill F7, and the leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction by adding the calculated second leveling correction amount ΔLv2 to the held first leveling correction amount ΔLv1 in the second control section B. Furthermore, during the period from when the tail end of the rolled material S passes through the meandering amount detection device 15 to when it passes through the controlled rolling mill F7, a third leveling correction amount ΔLv3 at the controlled rolling mill F7 is calculated based on the differential load ΔP calculated from the rolling loads on the work side and drive side of the controlled rolling mill F7 detected by the load detector 16, and in the third control section C, the leveling of the controlled rolling mill F7 is controlled so as to perform a leveling correction by adding the calculated third leveling correction amount ΔLv3 to the held first leveling correction amount ΔLv1 and second leveling correction amount ΔLv2.

[0099] In addition, in Example 2 of the present invention, from the time when the front end of the rolled material S passes through the controlled rolling mill F7 to the time when the tail end of the rolled material S passes through the upstream rolling mill F6, the first leveling correction amount ΔLv1 at the controlled rolling mill F7 is calculated based on the width-wise deviation ΔT of the tension in the steady portion of the rolled material S calculated from the width-wise distribution of the tension in the steady portion of the rolled material S detected by the tension detector 11 installed between the upstream rolling mill F6 and the controlled rolling mill F7. In addition, the second leveling correction amount ΔLv2 at the rolling mill F7 to be controlled was calculated based on the meandering amount δi of the rolling material S detected by the meandering amount detection device 15 installed between the rolling mill F6 to be controlled and the differential load ΔP calculated from the rolling loads on the work side and the drive side of the rolling mill F7 to be controlled detected by the load detector 16 installed in the rolling mill F7 to be controlled, during the period from when the tail end of the rolling material S passed through the previous rolling mill F6 to when it passed through the previous rolling mill F6 and the rolling mill F7 to be controlled. Furthermore, the third leveling correction amount ΔLv3 at the rolling mill F7 to be controlled was calculated based on the differential load ΔP calculated from the rolling loads on the work side and the drive side of the rolling mill F7 to be controlled detected by the load detector 16, during the period from when the tail end of the rolling material S passed through the meandering amount detection device 15 to when it passed through the rolling mill F7 to be controlled. Furthermore, in Example 2 of the present invention, a meandering amount prediction model generation step (step S11), a meandering amount prediction step (step S12), a judgment step (step S13), a leveling control step (step S14), a leveling correction amount correction step (step S15), and a leveling control step (step S16) were executed.

[0100] In the present invention example 2, in the meandering amount prediction model generation step (step S11), the meandering amount prediction model 210 was generated by machine learning using Chainer, a known deep learning framework. As learning data, 30,000 operation performance data were used. During the machine learning, a batch normalization method (wherein the batch size was set to 256) was used, and the Adam method was used to set the learning rate. The input performance data for the learning data includes information on the size of the rolled material S in the past (product dimensions (thickness, width, length), dimensions of the slab extracted from the heating furnace 2 (thickness, width, length), and the amount of camber at the front and rear ends of the rolled material S after rough rolling), information on the temperature of the rolled material S in the past (slab temperature at the time of extraction from the heating furnace (average value in the width direction, temperature at the center in the width direction, temperature at the ends in the width direction), and temperature of the sheet bar after rough rolling (average value in the width direction, temperature at the center in the width direction, temperature at the ends in the width direction)), information on the work rolls of the finishing rolling facility 4 in the past (number of rolls after changing the work rolls in each of F1 to F7, F The information on the past finishing rolling tension of the rolled material S was "the width direction distribution of the tension of the rolled material S detected by the tension detector 11 installed between the rolling mill F7 to be controlled and the rolling mill F6 in the previous stage and between the rolling mill F6 in the previous stage and the rolling mill F5 in the stage before previous," the actual first leveling correction amount in the rolling mill F7 to be controlled in the past, the actual second leveling correction amount in the rolling mill F7 to be controlled in the past, and the actual third leveling correction amount in the rolling mill F7 to be controlled in the past. The output actual data of the learning data was the actual meandering amount of the tail end of the rolled material S in the rear rolling mill F7 in the finishing rolling facility 4.

[0101] In the present invention example 2, in the meandering amount prediction step (step S12), the meandering amount prediction model 210 generated in the meandering amount prediction model generation step (step S11) is input with information on the size of the rolled material S in the current rolling pass "the dimensions of the product (thickness, width, length), the dimensions of the slab extracted from the heating furnace 2 (thickness, width, length), and the camber amount at the front and rear ends of the rolled material S after rough rolling", information on the temperature of the rolled material in the current rolling pass "the temperature of the slab at the time of extraction from the heating furnace (average value in the plate width direction, temperature at the center in the plate width direction, temperature at the ends in the plate width direction), and the temperature of the sheet bar after rough rolling (average value in the plate width direction, temperature at the center in the plate width direction, temperature at the ends in the plate width direction)", information on the work rolls of the finishing rolling equipment 4 in the current rolling pass "the work rolls in each of F1 to F7" The amount of meandering of the tail end of the rolled material S at the rear-stage rolling mill F7 was predicted by inputting "the number of rolled pieces after the work roll change, the type of work rolls at each of F1 to F7, the rolling tonnage after the work roll change at each of F1 to F7, and the mill stiffness difference at each of F1 to F7," information on the finish rolling tension of the rolled material S in the current rolling pass "the width direction distribution of the tension of the rolled material S detected by the tension detector 11 installed between the controlled rolling mill F7 and the preceding rolling mill F6 and between the preceding rolling mill F6 and the preceding rolling mill F5," the calculated first leveling correction amount ΔLv1 at the controlled rolling mill F7, the calculated second leveling correction amount ΔLv2 at the controlled rolling mill F7, and the calculated third leveling correction amount ΔLv3 at the controlled rolling mill F7.

[0102] In addition, in Example 2 of the present invention, the predetermined threshold value applied in the judgment step (step S13) was set to 30 mm, which is the average value of the difference between the widthwise spacing of the rolled material S and the spacing of a pair of side guides (not shown) installed on the inlet side of the finishing rolling equipment 4. Table 1 shows the measurement results of the amount of meandering of the tail end of the rolled material S in the rear rolling mill F7 when leveling control was performed for 100 pieces of rolled material S with a finishing thickness of 4 mm or less and a width of 1,600 mm or less in Comparative Example 1, Comparative Example 2, Invention Example 1, and Invention Example 2.

[0103] [Table 1]

[0104] In Table 1, absolute values ​​were used to calculate the average value μ (mm) and standard deviation 3σ of the amount of meandering of the tail end of the rolled material S in the rear-stage rolling mill F7. This is because meandering of x mm to the work side and meandering of x mm to the drive side have the same risk of drawing trouble. As shown in Table 1, in the case of Example 1 and Example 2 of the present invention, both the average value μ and the standard deviation 3σ of the amount of meandering of the tail end of the rolled material S in the rear-stage rolling mill F7 were improved compared to the case of Comparative Example 1 and Comparative Example 2, confirming the effect of reducing the amount of meandering of the rolled material S in the rear-stage rolling mill F7.

[0105] Furthermore, in the case of Example 2 of the present invention, the average value μ and standard deviation 3σ of the meandering amount of the tail end of the rolled material S in the rear stage rolling mill F7 were both improved compared to Example 1 of the present invention, and it was confirmed that the meandering amount of the rolled material S was further reduced by executing the meandering amount prediction model generation step (step S11), the meandering amount prediction step (step S12), the judgment step (step S13), and the leveling correction amount correction step (step S15). In addition, according to the manufacturing method of hot-rolled steel strip of the present invention, the amount of meandering of the rolled material S being finish-rolled can be reduced, and the productivity and yield in the hot rolling of the hot-rolled steel strip can be improved. [Explanation of symbols]

[0106] 1. Hot rolling equipment 2 Furnace 3 Roughing mill 4. Finishing rolling equipment 5 Runout Table 6 Winder 7 Leveling device 10 Leveling control device 11 Tension detector 12 Tension deviation calculation section 13 Imaging device 14. Meander amount calculation section 15 Meandering amount detection device 16 Load detector 17 Differential load calculation section 18 First leveling correction amount calculation unit 19 Second leveling correction amount calculation unit 20 Third leveling correction amount calculation unit 21. Mean-flow prediction model generation section 22 Meander amount prediction section 23 Judgment section 24 Leveling correction amount correction section 25 Leveling control section 26 Upper computer 27 Imaging Device 28 Image Processing Device 29 Shape detector 30 thermometer 210 Meander volume prediction model A First control section B. Second control section C. Third control section R1~RM Roughing stand F1~FN rolling mill Fn Rolling mill to be controlled S rolled material

Claims

1. A leveling control method in hot rolling for controlling meandering of a rolled material rolled in a finishing rolling facility equipped with a plurality of rolling mills, comprising: a first leveling correction amount calculation step of calculating a first leveling correction amount at the rolling mill to be controlled based on a width direction deviation of tension in a steady portion of the rolled material calculated from a width direction distribution of tension in the steady portion of the rolled material detected by a tension detector installed between the rolling mill to be controlled and the rolling mill to be controlled, during a period from when the front end portion of the rolled material passes through a rolling mill to be controlled among the plurality of rolling mills to when the tail end portion of the rolled material passes through a rolling mill to be controlled a second leveling correction amount calculation step of calculating a second leveling correction amount at the rolling mill to be controlled based on a meandering amount of the rolled material detected by a meandering amount detection device installed between the rolling mill to be controlled and a differential load calculated from the rolling loads on the working side and the driving side of the rolling mill to be controlled, detected by a load detector installed at the rolling mill to be controlled, during a period from when the tail end of the rolled material passes through the rolling mill to when it passes through the meandering amount detection device installed between the rolling mill to be controlled and the rolling mill to be controlled; a third leveling correction amount calculation step of calculating a third leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, which are detected by the load detector during the period from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled; and a leveling control step of controlling leveling of the rolling mill to be controlled so that a leveling correction by the first leveling correction amount is performed in a first control section from when the front end of the rolled material passes through the rolling mill to when the tail end of the rolled material passes through the previous rolling mill, a leveling correction by a leveling correction amount obtained by adding the second leveling correction amount to the first leveling correction amount is performed in a second control section from when the tail end of the rolled material passes through the previous rolling mill to when it passes through the meandering amount detection device, and a leveling correction by a leveling correction amount obtained by adding the first leveling correction amount and the second leveling correction amount to the third leveling correction amount is performed in a third control section from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled.

2. 2. The leveling control method for hot rolling according to claim 1, further comprising a meander amount prediction model generation step of: using as input data information on the past size of the rolled material, information on the past temperature of the rolled material, information on the past finish rolling tension of the rolled material, information on the work rolls of the finish rolling facility, a past actual first leveling correction amount at the rolling mill to be controlled, a past actual second leveling correction amount at the rolling mill to be controlled, and a past actual third leveling correction amount at the rolling mill to be controlled, and using as output data an actual meander amount of the tail end of the rolled material at a rear stage rolling facility in the finish rolling facility in response to the input data, by machine learning to generate a meander amount prediction model.

3. 3. The leveling control method for hot rolling according to claim 2, further comprising a meandering amount prediction step of predicting a meandering amount of the tail end portion of the rolled material at the rear stage rolling mill by inputting, into the meandering amount prediction model, information on the size of the rolled material at a current rolling pass, information on the temperature of the rolled material at the current rolling pass, information on the finish rolling tension of the rolled material at the current rolling pass, information on the work rolls of the finish rolling equipment at the current rolling pass, a first leveling correction amount at the rolling mill to be controlled calculated in the first leveling correction amount calculation step, a second leveling correction amount at the rolling mill to be controlled calculated in the second leveling correction amount calculation step, and a third leveling correction amount at the rolling mill to be controlled calculated in the third leveling correction amount calculation step.

4. 4. The leveling control method for hot rolling according to claim 3, further comprising a determination step of determining whether or not a predicted meandering amount of the tail end portion of the rolled material in the rear stage rolling mill predicted in the meandering amount prediction step is smaller than a predetermined threshold value.

5. 5. The leveling control method for hot rolling according to claim 4, further comprising a leveling correction amount correcting step of correcting a first leveling correction amount for the rolling mill to be controlled calculated in the first leveling correction amount calculating step, a second leveling correction amount for the rolling mill to be controlled calculated in the second leveling correction amount calculating step, and a third leveling correction amount calculated in the third leveling correction amount calculating step, so that the predicted meandering amount of the tail end of the rolled material in the rear stage rolling mill predicted in the meandering amount predicting step becomes smaller than the predetermined threshold value when a judgment result in the judging step is that the predicted meandering amount of the tail end of the rolled material in the rear stage rolling mill predicted in the meandering amount predicting step is equal to or greater than the predetermined threshold value.

6. In the leveling control step, when the judgment result in the judgment step is that the predicted meandering amount of the tail end portion of the rolled material in the rear-stage rolling mill predicted in the meandering amount prediction step is smaller than the predetermined threshold value, the leveling of the rolling mill to be controlled is controlled so as to implement, in the first control section, a leveling correction of the first leveling correction amount calculated in the first leveling correction amount calculation step, in the second control section, a leveling correction of a leveling correction amount obtained by adding the second leveling correction amount calculated in the second leveling correction amount calculation step to the first leveling correction amount, and in the third control section, a leveling correction of a leveling correction amount obtained by adding the first leveling correction amount and the second leveling correction amount to the third leveling correction amount calculated in the third leveling correction amount calculation step. In the leveling correction amount correction step, when the first leveling correction amount, the second leveling correction amount, and the third leveling correction amount are corrected, 6. The method for controlling leveling in hot rolling according to claim 5, characterized in that, instead of the leveling correction of the correction amount, the leveling correction of the leveling correction amount obtained by adding the second leveling correction amount to the first leveling correction amount in the second control section, and the leveling correction of the leveling correction amount obtained by adding the third leveling correction amount to the first leveling correction amount and the second leveling correction amount in the third control section, the leveling correction of the first leveling correction correction amount corrected in the leveling correction amount correction step is performed in the first control section, the leveling correction of the leveling correction amount obtained by adding the second leveling correction correction amount corrected in the leveling correction amount correction step to the first leveling correction correction amount in the second control section, and the leveling correction of the third leveling correction correction amount obtained by adding the first leveling correction correction amount and the second leveling correction correction amount to the first leveling correction correction amount and the second leveling correction correction amount in the third control section.

7. A leveling control device in hot rolling that controls the meandering of a rolled material being rolled in a finishing rolling facility equipped with a plurality of rolling mills, a first leveling correction amount calculation unit that calculates a first leveling correction amount at the rolling mill to be controlled based on a width direction deviation of tension in a steady portion of the rolled material calculated from a width direction distribution of tension in the steady portion of the rolled material detected by a tension detector installed between the rolling mill to be controlled and the rolling mill to be controlled, during a period from when a front end portion of the rolled material passes through a rolling mill to be controlled among the plurality of rolling mills to when a tail end portion of the rolled material passes through a rolling mill to be controlled a second leveling correction amount calculation unit that calculates a second leveling correction amount at the rolling mill to be controlled based on a meandering amount of the rolled material detected by a meandering amount detection device installed between the rolling mill to be controlled and a differential load calculated from the rolling loads on the working side and the driving side of the rolling mill to be controlled, the meandering amount of the rolled material detected by a load detector installed at the rolling mill to be controlled, during a period from when the tail end of the rolled material passes through the rolling mill to when it passes through the meandering amount detection device installed between the rolling mill to be controlled and the rolling mill to be controlled; a third leveling correction amount calculation unit that calculates a third leveling correction amount at the rolling mill to be controlled based on a differential load calculated from the rolling loads on the work side and the drive side of the rolling mill to be controlled, which are detected by the load detector during a period from when the tail end of the rolled material passes through the meandering amount detection device to when it passes through the rolling mill to be controlled; and a leveling control unit that controls leveling of the rolling mill to be controlled so as to perform leveling correction by the first leveling correction amount in a first control section from when the front end of the rolled material passes through the rolling mill to be controlled and when the tail end of the rolled material passes through the previous rolling mill, a leveling correction by a leveling correction amount obtained by adding the second leveling correction amount to the first leveling correction amount in a second control section from when the tail end of the rolled material passes through the previous rolling mill and when it passes through the meandering amount detection device, and a leveling correction by a leveling correction amount obtained by adding the first leveling correction amount and the second leveling correction amount to the third leveling correction amount in a third control section from when the tail end of the rolled material passes through the meandering amount detection device and when it passes through the rolling mill to be controlled.

8. 8. The leveling control device for hot rolling according to claim 7, further comprising a meander amount prediction model generation unit which generates a meander amount prediction model by machine learning a plurality of learning data in which past information on the size of the rolled material, past information on the temperature of the rolled material, past information on the finish rolling tension of the rolled material, past information on the work rolls of the finish rolling facility, past actual first leveling correction amounts at the rolling mill to be controlled, past actual second leveling correction amounts at the rolling mill to be controlled, and past actual third leveling correction amounts at the rolling mill to be controlled are used as input data, and past actual meander amounts of the tail end portion of the rolled material at a rear stage rolling mill in the finish rolling facility for this input data are used as output data.

9. 9. The leveling control device in hot rolling according to claim 8, further comprising a meandering amount prediction unit that predicts a meandering amount of the tail end portion of the rolled material at the rear stage rolling mill by inputting, into the meandering amount prediction model, information about the size of the rolled material at a current rolling pass, information about the temperature of the rolled material at the current rolling pass, information about the finish rolling tension of the rolled material at the current rolling pass, information about the work rolls of the finish rolling equipment at the current rolling pass, a first leveling correction amount at the rolling mill to be controlled calculated by the first leveling correction amount calculation unit, a second leveling correction amount at the rolling mill to be controlled calculated by the second leveling correction amount calculation unit, and a third leveling correction amount at the rolling mill to be controlled calculated by the third leveling correction amount calculation unit.

10. 10. The leveling control device for hot rolling according to claim 9, further comprising a judgment unit that judges whether a predicted meandering amount of the tail end portion of the rolled material in the rear stage rolling mill predicted by the meandering amount prediction unit is smaller than a predetermined threshold value.

11. 11. The leveling control device for hot rolling according to claim 10, further comprising a leveling correction amount correction unit that corrects a first leveling correction amount at the rolling mill to be controlled calculated by the first leveling correction amount calculation unit, a second leveling correction amount at the rolling mill to be controlled calculated by the second leveling correction amount calculation unit, and a third leveling correction amount calculated by the third leveling correction amount calculation unit, when a judgment result by the judgment unit indicates that a predicted meandering amount of the tail end of the rolled material at the rear stage rolling mill predicted by the meandering amount prediction unit is equal to or greater than the predetermined threshold value.

12. The leveling control unit controls the leveling of the rolling mill to be controlled so as to implement, when the judgment result of the judgment unit is that the predicted meandering amount of the tail end of the rolled material in the rear stage rolling mill predicted by the meandering amount prediction unit is smaller than the predetermined threshold value, a leveling correction of the first leveling correction amount calculated by the first leveling correction amount calculation unit in the first control section, a leveling correction of a leveling correction amount obtained by adding the second leveling correction amount calculated by the second leveling correction amount calculation unit to the first leveling correction amount in the second control section, and a leveling correction of a leveling correction amount obtained by adding the first leveling correction amount and the second leveling correction amount to the third leveling correction amount calculated by the third leveling correction amount calculation unit in the third control section, and when the leveling correction amount correction unit corrects the first leveling correction amount, the second leveling correction amount, and the third leveling correction amount, a leveling correction of the first leveling correction amount in the first control section is implemented.

12. The leveling control device for hot rolling according to claim 11, characterized in that the leveling control device controls the leveling of the rolling mill to be controlled so that, instead of the leveling correction of a leveling correction amount obtained by adding the second leveling correction amount to the first leveling correction amount in the second control section, and the leveling correction of a leveling correction amount obtained by adding the third leveling correction amount to the first leveling correction amount and the second leveling correction amount in the third control section, a leveling correction of a leveling correction amount obtained by adding the second leveling correction correction amount corrected by the leveling correction amount correction unit to the first leveling correction correction amount in the first control section, a leveling correction of a leveling correction amount obtained by adding the second leveling correction correction amount corrected by the leveling correction amount correction unit to the first leveling correction correction amount in the second control section, and a leveling correction of a leveling correction amount obtained by adding the first leveling correction correction amount and the second leveling correction correction amount to the third control section.

13. A hot rolling facility comprising the leveling control device according to any one of claims 7 to 12.

14. A method for producing a hot rolled steel strip, comprising: a finish rolling step of finish rolling the rolled strip by controlling the meandering of the rolled strip using the leveling control method according to any one of claims 1 to 6.

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