JP7736017B2 - Rolled material meandering amount prediction device, meandering amount control device, meandering amount prediction method, meandering amount control method, and metal strip manufacturing method - Google Patents

Description

The present invention relates to a device for predicting the meandering amount of a rolled material, a device for controlling the meandering amount, a method for predicting the meandering amount, a method for controlling the meandering amount, and a method for manufacturing a metal strip.

In hot finishing rolling mills, the material being rolled does not remain stable in the widthwise center of the rolls, and as rolling progresses, it can meander toward the widthwise edges of the rolls, creating a problem. When meandering occurs, the tail end of the material being rolled may collide with the side guides as it leaves the rolling stand, causing the widthwise edges of the material to bend and rolled, resulting in an operational problem known as "squeezing." When squeezing occurs, roll defects occur in the rolls, leading to problems such as reduced operation rates due to sudden roll changes, worsening roll consumption, and reduced yields due to the generation of semi-finished material.

To address this issue, it is common to adjust the leveling of the rolling mill (the difference in the roll gap between the drive side and work side of the rolling mill) to control meandering of the rolled material. However, once meandering of the rolled material occurs, a difference in rolling load (differential load) occurs between the drive side and work side of the rolling mill, resulting in a difference in the roll gap between the drive side and work side of the rolls. This creates a difference in the amount of roll reduction of the rolled material between the drive side and work side, increasing the curvature of the rolled material and further accelerating meandering. In other words, once meandering of the rolled material occurs, the amount of meandering of the rolled material increases, leading to squeezing. Against this background, a method has been proposed in which the factors that could cause meandering of the rolled material are identified in advance and the leveling of the rolling mill is adjusted before rolling.

For example, Patent Document 1 describes a method for suppressing meandering of the rolled material during the early stages of rolling in a tandem rolling mill equipped with multiple rolling stands. Specifically, this method first detects the entry off-center amount of the rolled material in the first rolling stand, the exit off-center amount of the rolled material in the final rolling stand, and the rolling load, differential load, and single-side reduction (leveling amount) for each rolling stand. Next, this method estimates the exit off-center amount of the rolled material in each rolling stand based on the detected values. This method then calculates a single-side reduction correction amount (leveling correction amount) so that the estimated exit off-center amount of the rolled material in each rolling stand is zero, and adjusts the leveling of each rolling stand according to the calculated single-side reduction correction amount before starting rolling of the next material.

Furthermore, Patent Document 2 describes a method for preventing meandering of a rolled material in both cases where the rolled material is off-center overall but not cambered, and where the rolled material is cambered. Specifically, this method first measures the amount of off-centering at the tip of the rolled material at the entry side of the first rolling stand of the finishing mill, and the amount of camber (bending) at each longitudinal position of the rolled material after rough rolling. Next, this method sets the leveling of the first rolling stand based on the measured amount of off-centering until the tip of the rolled material passes the first rolling stand of the finishing mill. Then, after the tip of the rolled material passes the first rolling stand, this method adjusts the leveling of the first rolling stand based on the measured amount of camber. Furthermore, this method also adjusts the roll gap from the second rolling stand onwards of the finishing mill based on the rolling conditions and the difference in mill stiffness between the left and right sides of each rolling stand to equalize the roll gap between the work side and the drive side.

Japanese Patent Application Publication No. 9-201613 Japanese Patent Application Laid-Open No. 2015-157317

The method described in Patent Document 1 uses the entry-side off-center amount of the tip of the material being rolled in the first rolling stand of a tandem rolling mill and the exit-side off-center amount of the tip of the material being rolled in the final rolling stand to suppress the off-center amount of the next material being rolled. Therefore, if the rolling conditions, such as material quality, thickness, and width, of the current and next rolled material are the same, a certain degree of meandering suppression effect can be expected. However, if the rolling conditions of the current and next rolled material are different, it may not be possible to suppress the off-center amount. Furthermore, it is difficult to suppress the off-center amount of the first rolled material after rearranging the roll rolls of a tandem rolling mill. On the other hand, the method described in Patent Document 2 achieves a certain degree of effectiveness when meandering of the rolled material occurring in the first rolling stand of a finishing mill is caused by camber or off-center of the rolled material at the entry side of the finishing mill. However, if the material being rolled has a wedge (deviation in thickness in the width direction) at the entry side of the finishing mill, or if the first rolling stand causes the material to meander, sufficient effectiveness cannot be achieved.

The present invention has been made to solve the above-mentioned problems, and its object is to provide a device and method for predicting the meandering amount of a rolled material, which are capable of predicting the amount of meandering at the tail end of the rolled material. Another object of the present invention is to provide a device and method for controlling the meandering amount of a rolled material, which are capable of reducing the amount of meandering at the tail end of the rolled material. Still another object of the present invention is to provide a method for manufacturing a metal strip, which is capable of producing a metal strip with reduced camber (bending) at the tail end.

The device for predicting the meandering amount of a rolled material according to the present invention is a device for predicting the meandering amount of the tail end of a rolled material in a rolling stand that constitutes a hot finishing rolling mill, and includes an entry wedge specifying unit that specifies the wedge amount of the tip end of the rolled material at the entry side of the rolling stand; an entry camber specifying unit that specifies the camber amount of the tip end of the rolled material at the entry side of the rolling stand; an exit camber specifying unit that specifies the camber amount of the tip end of the rolled material at the exit side of the rolling stand; and a tail end meandering amount prediction unit that predicts the meandering amount of the tail end of the rolled material in the rolling stand using the wedge amount of the tip end of the rolled material specified by the entry wedge specifying unit, the camber amount of the tip end of the rolled material specified by the entry camber specifying unit, and the camber amount of the tip end of the rolled material specified by the exit camber specifying unit.

The device for controlling the amount of meandering of a rolled material according to the present invention comprises a leveling setting value calculation unit that calculates a leveling setting value for the rolling stand based on the amount of meandering of the tail end of the rolled material predicted by the device for predicting the amount of meandering of a rolled material according to the present invention, and a leveling setting unit that sets the leveling of the rolling stand based on the leveling setting value calculated by the leveling setting value calculation unit during rolling of the steady portion of the rolled material.

The method for predicting the meandering amount of a rolled material according to the present invention is a method for predicting the meandering amount of the tail end of a rolled material in a rolling stand constituting a hot finishing mill, and includes an entry wedge identification step for identifying the wedge amount of the tip end of the rolled material at the entry side of the rolling stand; an entry camber identification step for identifying the camber amount of the tip end of the rolled material at the entry side of the rolling stand; an exit camber identification step for identifying the camber amount of the tip end of the rolled material at the exit side of the rolling stand; and a tail end meandering amount prediction step for predicting the meandering amount of the tail end of the rolled material in the rolling stand using the wedge amount of the tip end of the rolled material identified in the entry wedge identification step, the camber amount of the tip end of the rolled material identified in the entry camber identification step, and the camber amount of the tip end of the rolled material identified in the exit camber identification step.

The tail end meandering amount prediction step preferably includes a step of predicting the amount of meandering of the tail end of the rolled material in the rolling stand using a tail end meandering amount prediction model trained by machine learning, which includes as input the wedge amount of the tip end of the rolled material identified in the entry wedge identification step, the camber amount of the tip end of the rolled material identified in the entry camber identification step, and the camber amount of the tip end of the rolled material identified in the delivery camber identification step, and outputs the amount of meandering of the tail end of the rolled material in the rolling stand.

The method for controlling the meandering amount of a rolled material according to the present invention includes a leveling set value calculation step for calculating a leveling set value for the rolling stand based on the meandering amount of the tail end of the rolled material predicted by the method for predicting the meandering amount of a rolled material according to the present invention, and a leveling setting step for setting the leveling of the rolling stand based on the leveling set value calculated in the leveling set value calculation step during rolling of the steady portion of the rolled material.

The method for manufacturing a metal strip according to the present invention includes the step of manufacturing a metal strip using the method for controlling the meandering amount of a rolled material according to the present invention.

The rolled material meandering amount prediction device and meandering amount prediction method of the present invention make it possible to predict the meandering amount of the tail end of the rolled material. Furthermore, the rolled material meandering amount control device and meandering amount control method of the present invention make it possible to reduce the meandering amount of the tail end of the rolled material. Furthermore, the metal strip manufacturing method of the present invention makes it possible to manufacture a metal strip with reduced camber at the tail end.

FIG. 1 is a schematic diagram showing an example of the configuration of a hot rolling line including a hot finishing mill to which the present invention is applied. FIG. 2 is a schematic diagram showing an example of the configuration of a hot finishing mill to which the present invention is applied. FIG. 3 is a diagram showing an example of the configuration of one rolling stand that constitutes a hot finishing mill. FIG. 4 is a block diagram showing the configuration of a rolled material meandering amount prediction device according to one embodiment of the present invention. FIG. 5 is a diagram for explaining the definition of the wedge amount. FIG. 6 is a diagram for explaining the definition of the camber amount. FIG. 7 is a diagram for explaining the definition of the amount of meandering. FIG. 8 is a flowchart showing the flow of a method for predicting the meandering amount of a rolled material according to one embodiment of the present invention. FIG. 9 is a block diagram showing the configuration of a rolled material meandering amount control device according to one embodiment of the present invention. FIG. 10 is a flowchart showing the flow of a method for controlling the meandering amount of a rolled material according to one embodiment of the present invention. FIG. 11 is a block diagram showing the configuration of a tail-end meandering amount prediction model generation unit according to one embodiment of the present invention. FIG. 12 is a schematic diagram showing the configuration of a tail-end meandering amount prediction model using a neural network.

Below, with reference to the drawings, a device for predicting the meandering amount of a rolled material, a meandering amount control device, a meandering amount prediction method, a meandering amount control method, and a method for manufacturing a metal strip will be described in detail, which are embodiments of the present invention.

[Configuration of hot finishing rolling mill]
First, with reference to FIGS. 1 to 3, the configuration of a hot finishing mill (hereinafter sometimes simply referred to as a "finishing mill") to which the present invention is applied will be described.

FIG. 1 is a schematic diagram showing an example of the configuration of a hot rolling line including a hot finishing mill to which the present invention is applied. As shown in FIG. 1, the hot rolling line 1 includes a heating furnace 2, a descaling unit 3, a width reduction press unit 4, a roughing mill 5, a finishing mill 6, a cooling unit 7, and a coiler (winder) 8. A cast slab (not shown) is charged into the heating furnace 2, heated to a predetermined temperature, and extracted from the heating furnace 2 as a hot slab. The hot slab extracted from the heating furnace 2 has primary scale formed on its surface removed by the descaling unit 3, and then reduced in width to a predetermined width by the width reduction press unit 4. The reduced-width slab is then rolled to a predetermined thickness in the roughing mill 5 to form a rough bar (roughly rolled material), which is then transported to the finishing mill 6. In the finishing mill 6, the rough bar, which serves as the material to be rolled according to the present invention, is rolled to a product thickness using a continuous rolling mill equipped with five to seven rolling stands. Downstream of the finishing mill 6, a cooling device 7 is installed in a facility called a run-out table, and the material to be rolled is cooled to a predetermined temperature before being wound into a coil by a coiler 8.

Figure 2 is a schematic diagram showing an example configuration of a hot finishing rolling mill to which the present invention is applicable. As shown in Figure 2, the finishing rolling mill 6 is equipped with seven rolling stands (sometimes simply referred to as rolling mills), F1 to F7. An entry transport roll 10 is located on the entry side of the finishing rolling mill 6 (upstream in the direction of travel of the rolled material S), and a crop shear (not shown) is located further upstream of the entry transport roll 10 to cut and remove crops (irregularly shaped portions at the leading and trailing ends) of the rolled material S. The rolled material S, from which the crops at the leading and trailing ends have been removed by the crop shear, is passed sequentially through rolling stands F1 to F7. When the leading end of the rolled material S passes through the final rolling stand (final rolling stand) F7, "steady-state rolling" is achieved in which the rolled material S is being rolled in all of the rolling stands F1 to F7. The tail end of the rolled material S then passes through the rolling stands F1 to F7 in order, and the finish rolling of the rolled material S is completed when the tail end of the rolled material S passes through the final rolling stand F7. In this case, the process in which the front end of the rolled material S passes through the rolling stands F1 to F7 in order is called "threading," and the process in which the tail end of the rolled material S passes through the rolling stands F1 to F7 in order is called "tail removal." The present invention predicts and reduces the amount of meandering (off-center amount) of the rolled material S during the tail removal process in which the tail end of the rolled material S passes through each of the rolling stands F1 to F7 in order.

An exit transport roll 11 is located at the exit side of the finishing mill 6 (downstream in the direction of travel of the rolled material S). Together with the entry transport roll 10, it defines a pass line PL, which is the reference position in the vertical direction along which the rolled material S is transported. The pass line PL also serves as the reference position in the vertical direction when the rolled material S is rolled in each of the rolling stands F1-F7. Meanwhile, an interstand looper 12 is located between the rolling stands of the finishing mill 6 (between adjacent rolling stands). The interstand looper 12 is a device for adjusting the balance between the speed of the rolled material S being discharged from the upstream rolling stand and the speed of the rolled material S being charged into the downstream rolling stand. The height of the tip of the interstand looper 12 (looper roll) relative to the pass line PL is adjustable, and control is performed to maintain the tension applied to the rolled material S within a predetermined range during steady-state rolling of the rolled material S. However, during the process of threading the rolled material S, the looper rolls are already lowered to the height of the pass line PL, and control of the inter-stand looper 12 (looper control) is performed once the leading edge of the rolled material S reaches the downstream rolling stand. Also, during the process of the rolled material S passing through the tail end of the rolled material S, looper control is performed so that the looper rolls are lowered to the height of the pass line PL when the tail end of the rolled material S passes through the upstream rolling stand.

In this embodiment, for each rolling stand F1 to F7, the upstream side in the direction of travel of the rolled material S is referred to as the "entrance side," and the downstream side in the direction of travel of the rolled material S is referred to as the "exit side." In this case, the entry side of rolling stand F3 refers to the area between rolling stand F2 and rolling stand F3, which are the upstream rolling stands, and the exit side of rolling stand F3 refers to the area between rolling stand F4 and rolling stand F3, which are the downstream rolling stands. Note that the entry side of rolling stand F1, which is the first rolling stand, refers to the area between rolling stand F1 and the crop shear located upstream of it. On the other hand, the exit side of rolling stand F7, which is the final rolling stand, refers to the area between rolling stand F7 and the run-out table located downstream of it.

The finishing mill 6 is equipped with a programmable logic controller (PLC) 90 for controlling each piece of equipment constituting the finishing mill 6, and a control computer (process computer) 91 for issuing control commands to the control controller 90. The hot rolling line 1 is also equipped with a host computer 92 for issuing production instructions to each piece of equipment, including the finishing mill 6. Rolling control in the finishing mill 6 is carried out by the control computer 91 setting operating conditions for the material S to be rolled based on the host computer 92 or production instructions from the host computer 92. The control controller 90 also has the function of collecting information obtained from various sensors (thickness gauge, width gauge, thermometer, etc.) installed in the finishing mill 6 at a predetermined sampling period and outputting this information to the control computer 91.

Figure 3 illustrates an example of the configuration of one rolling stand that makes up the finishing rolling mill 6. As shown in Figures 3(a) and (b), the rolling stand has a pair of work rolls 61a, 61b arranged vertically on either side of the pass line PL. The work rolls 61a, 61b are supported by backup rolls 62a, 62b, respectively. One end of each of the work rolls 61a, 61b is connected to a drive motor via a coupling or a reducer. The drive motor rotates the work rolls 61a, 61b. In this case, the side of the rolling stand on which the drive motor is located is sometimes called the drive side (DS), and the opposite side is sometimes called the work side (WS).

Backup rolls 62a, 62b are supported by bearing housings (backup roll chocks) 63a, 63b located at their axial ends. The rolling load applied to the rolled material S is transmitted to housings 64a, 64b via backup roll chocks 63a, 63b. Load cells 65a, 65b, which act as load detectors, are located between the housings 64a, 64b and the backup roll chocks 63a, 63b, allowing the rolling load applied to the rolled material S to be measured. In this case, the sum of the measurements taken by load cell 65a and load cell 65b is called the rolling load or sum load, and the difference between the measurements taken by load cell 65a and load cell 65b is sometimes called the differential load.

Screw reduction devices 66a, 66b are located on the work side and drive side of the rolling stand. The screw reduction devices 66a, 66b adjust the gap (also called the roll gap or roll opening) between the work rolls 61a and 61b by vertically displacing the backup roll chocks 63a, 63b, respectively. The vertical positions of the backup roll chocks 63a, 63b are typically configured so that they can be measured using a displacement gauge (not shown). Because it is difficult to actually measure the gap between the work rolls 61a and 61b, the roll opening is conventionally set by the vertical position of the backup roll chocks 63a, 63b.

The screw-down devices 66a, 66b are equipped with electric or hydraulic screw-down mechanisms. Hydraulic screw-down mechanisms (also called hydraulic screw-downs) displace the backup roll chocks 63a, 63b up and down by controlling the hydraulic pressure of a hydraulic cylinder. Electric screw-down devices (also called electric screw-downs) displace the backup roll chocks 63a, 63b up and down by rotating an electric motor for the screw-down device and moving the screw-down screws up and down via gears. The screw-down devices 66a, 66b are not limited to a system that displaces the backup roll 62a up and down from the top of the housings 64a, 64b, but may also be a system that displaces the backup roll 62b up and down from the bottom of the housings 64a, 64b.

The screw-down devices 66a, 66b typically set the vertical positions of the backup roll chocks 63a, 63b so that the gap between the work rolls 61a and 61b is the same on the work side and the drive side. However, the vertical positions of the backup roll chocks 63a, 63b may be set differently. Setting the vertical positions of the backup roll chocks 63a, 63b to be different is called leveling, and the difference in the vertical positions of the backup roll chock 63a on the work side and the backup roll chock 63b on the drive side is sometimes called the leveling amount. Leveling is intended to create a difference in the roll gap between the work side and the drive side work rolls, but in reality it is performed by creating a difference in the vertical positions of the backup roll chocks 63a, 63b, as described above.

[Meandering amount prediction device]
Next, the configuration of a rolled material meandering amount prediction device according to one embodiment of the present invention will be described with reference to FIGS.

Figure 4 is a block diagram showing the configuration of a rolled material meandering amount prediction device, which is one embodiment of the present invention. As shown in Figure 4, a rolled material meandering amount prediction device 20, which is one embodiment of the present invention, includes an entry wedge identification unit 21, an entry camber identification unit 22, an exit camber identification unit 23, and a tail end meandering amount prediction unit 24.

The entry wedge determination unit 21 determines the wedge amount of the tip of the rolled material S at the entry side of the rolling stand F that constitutes the finishing rolling mill 6. The wedge of the rolled material S refers to a state in which the rolled material S has a thickness deviation in the width direction. The thickness deviation in the width direction of the rolled material S is called the wedge amount. Specifically, the wedge amount is defined as the difference between the thickness h1 of the rolled material S at a predetermined distance We from the work-side width end and the thickness h2 of the rolled material S at a distance We from the drive-side width end in the cross-sectional shape of the rolled material S shown in Figure 5. In this case, a positive wedge amount may be defined as a case in which the thickness h1 at the work-side width end is greater than the thickness h2 at the drive-side width end, and a negative wedge amount may be defined as a case in which the thickness h1 at the work-side width end is smaller than the thickness h2 at the drive-side width end. The distance We from the width end, which serves as the basis for the wedge amount, is set, for example, in the range of 15 to 200 mm.

Returning to Figure 4, the entry wedge identification unit 21 may be configured to install a wedge meter 31 on the entry side of the rolling stand F and identify the wedge amount at the leading end of the rolled material S based on measurements taken by the wedge meter 31. The wedge meter 31 may be, for example, a thickness gauge using X-rays or gamma rays, installed in multiple locations across the width of the rolled material S, and measure the thickness h1 of the rolled material S at the widthwise end of the work side and the thickness h2 of the rolled material S at the widthwise end of the drive side. The wedge meter 31 may also be configured to scan the thickness gauge across the width of the rolled material S to measure the widthwise thickness distribution of the rolled material S and calculate the wedge amount from the measured thickness distribution. Furthermore, laser scanning distance meters may be installed on the front and back sides of the rolled material S, and the thickness of the rolled material S may be calculated from the difference between the distance information obtained on the front side and the distance information obtained on the back side using distance information measured by the distance meters at each position across the width of the rolled material S.

In this embodiment, the entry wedge identifier 21 identifies the wedge amount obtained at the leading edge of the rolled material S. Here, the "leading edge" of the rolled material S in this embodiment refers to the area of the rolled material S that exists between the rolling stands from the time the rolled material S passes through one rolling stand until it is engaged with the next rolling stand during the sheet threading process of the finishing rolling mill 6. In this case, the area of the rolled material S that exists between the rolling stands from when the leading edge of the rolled material S (the foremost part of the rolled material S) passes through the rolling stand F-1 upstream of the rolling stand F to when it reaches the next rolling stand F is referred to as the leading edge of the rolled material S on the entry side of the rolling stand F. Furthermore, the area of the rolled material S that exists between the rolling stands from when the leading edge of the rolled material S passes through the rolling stand F to when it reaches the next rolling stand F+1 is referred to as the leading edge of the rolled material S on the exit side of the rolling stand F.

Meanwhile, in this embodiment, the "tail end" of the rolled material S refers to the range of the rolled material S that exists between the rolling stands during the tail-out process of the finishing rolling mill 6, from when the tail end (the tailmost part of the rolled material S) of the rolled material S leaves one rolling stand until the tail end of the rolled material S leaves the next rolling stand. In this case, the range of the rolled material S that exists between the rolling stands from when the tail end of the rolled material S leaves the upstream rolling stand F-1 to when it reaches rolling stand F is referred to as the tail end of the rolled material S on the entry side of rolling stand F. Furthermore, the range of the rolled material S that exists between the rolling stands from when the tail end of the rolled material S leaves rolling stand F until the tail end of the rolled material S leaves the downstream rolling stand F+1 is referred to as the tail end of the rolled material S on the exit side of rolling stand F.

The entry camber determination unit 22 determines the amount of camber at the tip of the rolled material S at the entry side of the rolling stand F. The exit camber determination unit 23 determines the amount of camber at the tip of the rolled material S at the exit side of the rolling stand F. The amount of camber (amount of curvature) at the tip of the rolled material S refers to the difference between the widthwise center position at the tip of the rolled material S and the widthwise center position at a position a predetermined distance away from the tip of the rolled material S. The amount of camber of the rolled material S is sometimes referred to as the amount of lateral curvature.

As shown in FIG. 6 , the camber amount Cam of the tip of the rolled material S is expressed as the difference between the distance y1 and the distance y2, where _y1 is the distance between the widthwise center position P0 of the rolling stand F and the widthwise center position of the tip of the rolled material S, and y2 is the distance between the widthwise center position P0 of the rolling stand F and the widthwise center position of the rolled material S at a position a distance _z away from the tip of the rolled material S. In this case, _positive and negative camber amounts may be defined depending on the direction of the bend of the rolled material S, with a positive camber amount being defined when the rolled material S is bent toward the work side and _a negative camber amount being defined when the rolled material S is bent toward the drive side. The distance z from the tip of the rolled material S, which serves as the basis for the camber amount, may be set arbitrarily, with the distance between the rolling stands as an upper limit. Specifically, the distance z is set in the range of 500 to 6000 mm.

Returning to Figure 4, the entry camber determination unit 22 and the exit camber determination unit 23 can be fitted with measuring devices capable of measuring the leading edge of the rolled material S and the widthwise position of the rolled material S at a position a distance z from the leading edge. The entry camber determination unit 22 and the exit camber determination unit 23 can be configured, for example, by providing an entry camera 32 on the entry side of the rolling stand F that images the leading edge of the rolled material S from the top or bottom, and an exit camera 33 on the exit side of the rolling stand F that images the leading edge of the rolled material S from the top or bottom, and applying image processing to the images of the leading edge of the rolled material S captured by the entry camera 32 and the exit camera 33 to determine the camber amount of the rolled material S. In this case, the entry camera 32 should be positioned so that it can image the surface of the leading edge of the rolled material S from above between the rolling stands on the entry side of the rolling stand F. Additionally, the exit camera 33 should be positioned so that it can photograph the surface of the leading edge of the rolled material S from above between the rolling stands on the exit side of the rolling stand F. This allows the entry camera 32 and the exit camera 33 to capture an image of the leading edge of the rolled material S, as shown in Figure 6.

Returning to Figure 4, the entry camber determination unit 22 and the exit camber determination unit 23 extract the contour shape of the rolled material S by image processing from the images of the leading edge of the rolled material S acquired by the entry camera 32 and the exit camera 33, respectively, and determine the camber amount of the rolled material S based on the extracted contour shape of the rolled material S. In this case, in order to convert the dimensions of the images acquired by the cameras to an actual scale, the correspondence between the distance between pixels and the actual distance is determined in advance.

The timing at which the wedge amount determined by the entry wedge determination unit 21, the camber amount determined by the entry camber determination unit 22, and the camber amount determined by the exit camber determination unit 23 are acquired differs depending on the locations of the respective measuring instruments and imaging devices. In this case, the control controller 90 constantly tracks the leading edge of the rolled material S to control the threading process of the rolled material S. Therefore, it is advisable to use the tracking information generated by the control controller 90 to adjust the timing at which the wedge amount of the rolled material S is measured by the wedge meter 31 and the timing at which the entry camera 32 and the exit camera 33 capture images of the rolled material S.

The tail end meandering amount prediction unit 24 predicts the amount of meandering of the tail end of the rolled material S in the rolling stand F using the wedge amount specified by the entry wedge specifying unit 21, the camber amount specified by the entry camber specifying unit 22, and the camber amount specified by the delivery camber specifying unit 23. Meandering of the tail end of the rolled material S refers to the deviation of the widthwise center position of the rolled material S from the widthwise center position of the rolling stand F (also referred to as off-center) when the tail end of the rolled material S passes through the rolling stand F, and the amount of meandering means the amount of deviation (also referred to as off-center amount). As shown in Figure 7(a), the amount of meandering of the tail end of the rolled material S can be defined by the difference _yc between the widthwise center position P0 of the rolling stand F and the widthwise center position of the tail end of the rolled material S when the tail end of the rolled material S tails out of the rolling stand F. Furthermore, as shown in FIG. 7( b), the amount of meandering of the tail end of the rolled material S may be defined as the difference _yc between the widthwise center position of the tail end of the rolled material S at a position a predetermined distance _zc away upstream of the rolling stand F and the widthwise center position P0 of the rolling stand F. Either of these is an index representative of the meandering behavior of the tail end of the rolled material S. In this case, the distance _zc for specifying the amount of meandering can be set arbitrarily, with the distance between the rolling stands as its upper limit. For example, the distance _zc may be set in the range of 0 to 6000 mm. Furthermore, as with the amount of camber, the direction of meandering may be defined as positive or negative depending on the direction in which the tail end of the rolled material S is deviated, with a positive meandering amount being defined when the rolled material S is deviated toward the work side and a negative meandering amount being defined when the rolled material S is deviated toward the drive side. Note that the case in which the distance _zc in FIG. 7( b) is set to zero corresponds to the state shown in FIG. 7( a).

Meandering of the rolled material S occurs when there is a difference in the reduction amount or reduction rate between the drive side and the work side of the rolled material S, resulting in a distribution of the progress speed in the width direction of the rolled material S. In particular, when the tail end of the rolled material S passes through rolling stand F, the rolled material S is constrained by the work rolls in the downstream rolling stand F+1, whereas the tail end of the rolled material S passes through the upstream rolling stand F-1 and is not constrained in its displacement in the width direction. For this reason, the tail end of the rolled material S passing through rolling stand F is more susceptible to meandering than the steady portion. As a result, meandering of the tail end of the rolled material S occurs at the entry side of rolling stand F, where the tail end is about to pass. The difference in the amount or rate of reduction between the drive side and the work side of the rolled material S can occur because the leveling of the rolling stand is not set properly, or because even if the leveling is generally correct, there is a wedge in the rolled material S, which causes a difference in reduction between the work side and the drive side.

The tail end meandering amount prediction unit 24 estimates the actual leveling value of the rolling stand F based on the wedge at the front end of the rolled material S and the camber amount at the entry and exit sides of the rolling stand F (leveling estimation step). Then, if the estimated actual leveling value is maintained until the steady-state rolling and tailing out process of the rolled material S, the tail end meandering amount prediction unit 24 predicts the amount of meandering of the tail end that will occur when the rolled material S tails out (meandering amount prediction step).

As mentioned above, rolling stand leveling refers to imparting a difference in roll gap between the work rolls on the work side and the drive side. In practice, however, this is set by imparting a difference in the vertical positions of the backup roll chocks 63a, 63b on the work side and the drive side (command leveling). However, due to the effects of thermal expansion and wear on the backup rolls 62a, 62b and work rolls 61a, 61b that make up the rolling stand, the command leveling set by the screw down devices 66a, 66b does not necessarily coincide with the difference in the roll gap between the work rolls 61a, 61b on the work side and the drive side. In this embodiment, the tail end meandering amount prediction unit 24 estimates the actual value of the difference in the roll gap between the work rolls 61a, 61b on the work side and the drive side during the threading process of the leading edge of the rolled material S, and calculates the estimated actual value of leveling as the estimated leveling value. The tail end meandering amount prediction unit 24 then uses the calculated leveling estimate value to predict the amount of meandering at the tail end of the rolled material S.

The leveling estimation value _Sd estimated by the leveling estimation step can be calculated by the function formula f shown in the following formula (1) using the wedge amount _Hd (mm) specified by the entry wedge specifying unit 21, the camber amount _Ci (mm) specified by the entry camber specifying unit 22, and the camber amount _Co (mm) specified by the exit camber specifying unit 23.

Here, H is the thickness (mm) of the rolled material S at the entry side of the rolling stand F, h is the thickness (mm) of the rolled material S at the exit side of the rolling stand F, z is the distance (mm) from the tip of the rolled material S to determine the camber amount, _Kp is the parallel rigidity (kN/mm) of the rolling stand F, M is the plasticity coefficient (kN/mm), P is the rolling load (kN), λ is the elongation rate of the rolled material S by the rolling stand F (the elongation rate of the material length at the exit side relative to the material length at the entry side), b is the width (mm) of the rolled material S, and L is the distance between the screw down devices 66a and 66b that screw down the backup roll chocks 63a and 63b on the work side and drive side (see Figure 3).

The parallel stiffness _Kp is an index showing how easily the work rolls 61a and 61b can be maintained in parallel when a differential load occurs between the work rolls 61a and 61b, and in the case of a four-high rolling mill, for example, it can be calculated by the following equation (2):

where K is the mill constant (kN/mm), _kr is the spring constant (kN/mm) representing the flattening deformation between the work roll and the backup roll, _ks is the spring constant (kN/mm) representing the flattening deformation of the work roll that occurs between the work roll and the material S to be rolled, and _Lb is the barrel length of the work roll (m).

The plasticity coefficient M is an index that represents the change in rolling load relative to the change in thickness of the rolled material S, and can be calculated using the following formula (3):

Further, as an index representing a change in differential load relative to a change in the wedge amount on the entry side and the wedge amount on the delivery side of the rolling stand F, the parallel plastic coefficient _Mp can be defined as shown in the following mathematical formula (4).

Here, the above-mentioned function formula f will be specifically derived. For example, if it is assumed that the curvature (camber) of the leading end of the rolled material S can be approximated by a parabola (quadratic equation) along the longitudinal direction of the rolled material S, and the distribution of the rolling load along the width direction of the rolled material S can be approximated by a straight line, the estimated leveling value _Sd can be obtained as shown in the following formula (5).

Here, _a0 , _a1 , and _a2 are parameters that represent the shape of the camber when the camber (curvature) at the front end of the rolled material S is approximated by a parabola (quadratic equation) along the longitudinal direction of the rolled material S. Specifically, _a0 , _a1 , and _a2 are determined by the relationship shown in the following equation (6) using the distances _y1 and _y2 shown in Figure 6.

On the other hand, a numerical analysis method such as the finite element method may be used to perform a plurality of calculations by changing each parameter regarding the relationship between the wedge amount _Hd , the camber amount _Ci , and the camber amount _Co and the estimated leveling value _Sd of the rolling stand F. Then, from the results of the obtained numerical calculations, a regression equation may be calculated in which the wedge amount _Hd , the camber amount _Ci , and the camber amount _Co are used as input variables and the estimated leveling value _Sd of the rolling stand F is used as an output variable, and the estimated leveling value _Sd of the rolling stand F may be obtained using the calculated regression equation. In this case, numerical analysis may be performed by changing rolling conditions such as the thickness H of the rolled material S at the entry side of the rolling stand F, the thickness h of the rolled material S at the delivery side of the rolling stand F, the deformation resistance of the rolled material S, and the friction coefficient of the rolling stand F, and these may be included as input variables in the regression equation.

In this manner, the actual leveling value (estimated leveling value S _d ) of the rolling stand F is estimated based on the information acquired during the process of threading the leading end of the rolled material S.

Next, the tail end meandering amount prediction unit 24 estimates the amount of meandering of the tail end of the rolled material S in the case where the estimated leveling estimated value _Sd is maintained until the tailing out process of the rolled material S. Specifically, assuming that the leveling estimated value _Sd is maintained during the tailing out process and the wedge amount _Hd of the rolled material S at the entry side of the rolling stand F is the same at the front end and the tail end of the rolled material S, the wedge amount _hd of the rolled material S at the delivery side of the rolling stand F can be calculated by the following equation (7).

The wedge amount h _d of the rolled material S at the delivery side of the rolling stand F calculated in this manner is used to calculate the wedge ratio change of the rolled material S that occurs in the rolling stand F. The wedge ratio change is an index that represents the change in the wedge amount of the rolled material S at the entry side and delivery side of the rolling stand F. Specifically, the wedge ratio Ψ ₁ of the rolled material S at the entry side of the rolling stand F and the wedge ratio Ψ ₂ of the rolled material S at the delivery side of the rolling stand are defined by the following equation (8), and the wedge ratio change ΔΨ is defined by the following equation (9).

From this, the wedge ratio change ΔΨ at the tail end that occurs when the rolled material S tails off can be calculated using the following formula (10):

The change in wedge ratio ΔΨ of the tail end portion that occurs when the rolled material S tails out represents the rotational behavior within the plane of the rolled material S, and therefore the amount of meandering _yc of the tail end portion that occurs when the rolled material S tails out can be calculated using the following formula (11): However, formula (11) is calculated on the assumption that the meandering of the tail end portion that occurs when the rolled material S tails out occurs after the tail end of the rolled material S leaves the upstream rolling stand F-1, and that the rolled material S is constrained at the delivery side of the downstream rolling stand.

Here, d is the distance between the rolling stand F and the upstream stand F-1. In this case, if the distance _zc is set to zero as shown in FIG. 7(a), the amount of meandering _yc is expressed by the following formula (12).

[Meandering amount prediction method]
Next, a method for predicting the meandering amount of a rolled material according to one embodiment of the present invention will be described with reference to FIG.

8 is a flowchart showing the flow of a method for predicting the meandering amount of a rolled material according to one embodiment of the present invention. As shown in FIG. 8, in the method for predicting the meandering amount of a rolled material according to one embodiment of the present invention, first, the entry wedge specifying unit 21 specifies the wedge amount _Hd of the leading edge of the rolled material S obtained at the entry side of the rolling stand F (step S1). Next, the entry camber specifying unit 22 specifies the camber amount _Ci of the leading edge of the rolled material S obtained at the entry side of the rolling stand F (step S2). Next, the delivery camber specifying unit 23 specifies the camber amount _Co of the leading edge of the rolled material S obtained at the delivery side of the rolling stand F (step S3). Next, based on this information specified during the threading process of the leading edge of the rolled material S, the tail end meandering amount predicting unit 24 calculates an estimated leveling value _Sd of the rolling stand F (step S4). Then, the tail end meandering amount predicting unit 24 predicts the meandering amount _yc of the tail end portion of the rolled material S using the estimated leveling value _Sd (step S5).

[Meandering amount control device]
Next, the configuration of a device for controlling the amount of meandering of a rolled material according to one embodiment of the present invention will be described with reference to FIG.

Figure 9 is a block diagram showing the configuration of a rolled material meandering amount control device according to one embodiment of the present invention. As shown in Figure 9, a rolled material meandering amount control device 40 according to one embodiment of the present invention includes a leveling set value calculation unit 41 and a leveling setting unit 42. The leveling set value calculation unit 41 calculates a leveling set value for reducing meandering at the tail end of the rolled material S based on the amount of meandering at the tail end of the rolled material S in the rolling stand F predicted by the meandering amount prediction device 20. The leveling setting unit 42 sets the leveling of the rolling stand F based on the leveling set value calculated by the leveling set value calculation unit 41 while the rolling stand F is rolling the steady portion of the rolled material S.

[Meandering amount control method]
Next, a method for controlling the meandering amount of a rolled material according to one embodiment of the present invention will be described with reference to FIG.

FIG. 10 is a flowchart showing the flow of a method for controlling the meandering amount of a rolled material according to one embodiment of the present invention. In this method, a limit value (limit meandering amount) for the meandering amount of the tail end of the rolled material S is preset in the leveling set value calculation unit 41. As shown in FIG. 10, in this method, the meandering amount prediction device 20 first predicts the meandering amount (predicted meandering amount) of the tail end of the rolled material S at the entry side of the rolling stand F (step S11). Next, the leveling set value calculation unit 41 determines whether the predicted meandering amount is equal to or less than the limit meandering amount (step S12). If the result of the determination is that the predicted meandering amount is equal to or less than the limit meandering amount (step S12: Yes), the leveling set value calculation unit 41 determines a leveling set value so as to maintain the current leveling setting (initial leveling setting) (step S13). On the other hand, if the predicted meandering amount exceeds the limit meandering amount (step S12: No), the leveling setting value calculation unit 41 determines the leveling setting value as follows (step S14).

First, the leveling set value calculation unit 41 determines whether the predicted meandering amount is positive or negative, and determines whether the tail end of the rolled material S will meander toward the work side or the drive side of the rolling stand F. If it is predicted that the tail end of the rolled material S will meander toward the work side, the leveling set value calculation unit 41 sets a new leveling set value so that the roll gap on the work side is narrower than the commanded leveling that is set in advance. On the other hand, if it is predicted that the tail end of the rolled material S will meander toward the drive side, the leveling set value calculation unit 41 sets a new leveling set value so that the roll gap on the drive side is narrower than the commanded leveling. For example, if a meandering amount of 10 to 100 mm is predicted, the leveling set value calculation unit 41 may set a new leveling set value so that the commanded leveling is changed by approximately 0.01 to 0.1 mm.

On the other hand, the leveling set value calculation unit 41 may determine the leveling set value so as to make the predicted meandering amount zero. In this case, the leveling set value calculation unit 41 calculates the wedge ratio change (target wedge ratio change) ΔΨ _aim of the rolled material S for making the predicted meandering amount zero by the following formula (13). Then, the leveling set value calculation unit 41 calculates a leveling correction amount _ΔSd for the leveling estimated value _Sd from the condition that satisfies the following formula (14).

This enables the leveling set value calculation unit 41 to determine the leveling correction amount _ΔSd for setting the predicted meandering amount to zero. Then, the leveling set value calculation unit 41 determines the leveling amount by adding the leveling correction amount _ΔSd to the current leveling set value (command leveling) as the new leveling set value. The limit meandering amount is determined as the limit meandering amount at which squeezing due to meandering of the rolled material S does not occur. Specifically, the relationship between the meandering amount of the tail end of the rolled material S at the inlet side of the rolling stand F and the occurrence rate of squeezing may be investigated in advance, and the maximum meandering amount of the tail end at which squeezing does not occur may be set as the limit meandering amount. Alternatively, since squeezing occurs when the rolled material S collides with the side guides, the limit meandering amount may be determined based on the distance between the side guides.

Finally, the leveling setting unit 42 sets the leveling of the rolling stand F based on the leveling setting value calculated by the leveling setting value calculation unit 41 while the rolling stand F is rolling the steady portion of the rolled material S (step S15). The change to the new leveling setting value is performed during steady rolling of the rolled material S. This updates the leveling setting to one suitable for the tail end of the rolled material S to tail off before the tail end of the rolled material S begins to tail off, reducing meandering when the tail end of the rolled material S tails off. Furthermore, even if the leveling setting for the rolled material S is performed during steady rolling, continuous rolling of the rolled material S is being performed in the rolling stands upstream and downstream of the rolling stand F. Therefore, the constraint of the rolled material S by each rolling stand is less likely to promote meandering of the rolled material S during steady rolling.

The leveling setting unit 42 receives tracking information regarding the biting and tailing of each rolling stand generated by the control controller 90, and after the threading process of the rolled material S is completed and the steady rolling process begins, sends a command to the control controller 90 for a new leveling setting value for the rolling stand F. This causes the control controller 90 to send a command to the screw down devices 66a, 66b of the rolling stand F to achieve the set leveling.

[Modification]
The entry wedge specifying unit 21 may estimate the entry wedge amount of a rolling stand downstream of the first rolling stand, using the entry wedge amount of the first rolling stand specified using the wedge meter 31 and the leveling estimated value of the rolling stand specified in the leveling estimation step. In this case, the entry wedge specifying unit 21 utilizes the wedge amount on the delivery side of rolling stand F to calculate the entry wedge amount _Hd2 of rolling stand F+1 using the following equation (15):

The tail end meandering amount prediction unit 24 may predict the meandering amount of the tail end of the rolled material S using a tail end meandering amount prediction model that predicts the meandering amount of the tail end of the rolled material S through learning using machine learning. The tail end meandering amount prediction model can be one learned through machine learning, which includes as input the wedge amount identified by the entry wedge identification unit 21, the camber amount identified by the entry camber identification unit 22, and the camber amount identified by the exit camber identification unit 23, and outputs the meandering amount of the tail end of the rolled material S at the entry side of the rolling stand.

Now, with reference to Figure 11, the configuration of the tail end meandering amount prediction model generation unit, which is one embodiment of the present invention, will be described. As shown in Figure 11, the tail end meandering amount prediction model generation unit 100, which is one embodiment of this embodiment, includes a database unit 101 and a machine learning unit 102. The database unit 101 accumulates actual data on the wedge amount identified by the entry wedge identification unit 21, actual data on the camber amount identified by the entry camber identification unit 22, actual data on the camber amount identified by the exit camber identification unit 23, and actual data on the meandering amount of the tail end of the material S to be rolled at the entry side of the rolling stand F. The actual data on the meandering amount of the tail end of the material S to be rolled at the entry side of the rolling stand F can be obtained by obtaining the amount of deviation of the material S from the center position in the width direction of the rolling mill when the camber amount is identified using the entry camber identification unit 22.

The database unit 101 may, as necessary, store one or more pieces of actual data selected from the rolling operation parameters of the rolling stand F. The rolling operation parameters of the rolling stand F are operation parameters that specify the rolling conditions at the front end of the rolled material S in the rolling stand F, and may include, for example, the rolling load, differential load, entry thickness, exit thickness, interstand tension during steady rolling, and the deformation resistance and temperature of the rolled material. This is because the rolling load and differential load of the rolled material S affect the elastic deformation of each rolling roll constituting the rolling stand F and affect the roll gap distribution in the width direction of the work rolls 61a, 61b. Other operation parameters also indirectly affect the rolling load. Furthermore, the database unit 101 may, as necessary, store one or more pieces of actual data selected from operation parameters related to the temperature change in the longitudinal direction of the rolled material S. The operation parameters related to the temperature change in the longitudinal direction of the rolled material S are parameters that affect the temperature change from the front end to the tail end of the rolled material S. Specifically, these include the length, weight, rolling speed, and acceleration rate of the material S to be rolled. These affect the rolling time in the rolling stand F from when the material S is threaded until it reaches the bottom, and affect the temperature change from the front to the tail end of the material S to be rolled. The temperature change from the front to the tail end of the material S to be rolled affects the thermal expansion of the work rolls not only in the rolling stand F but also in the upstream stands. This causes fluctuations in the wedge amount from the front to the tail end of the material S to be rolled, which affects the amount of meandering at the tail end of the material S to be rolled.

Furthermore, the database unit 101 may store one or more pieces of actual data selected from the rolling operation parameters of the roughing mill 5, as necessary. The rolling operation parameters of the roughing mill 5 refer to parameters that specify the rolling conditions of the roughing mill 5 before the material S to be rolled is loaded into the finishing mill 6. Specifically, these include the number of rolling passes by the roughing mill 5, the rolling load, differential load, and off-center amount in each rolling pass of the roughing mill 5, and the width reduction amount by the edger placed in the roughing mill 5. The number of rolling passes, rolling load, differential load, and off-center amount by the roughing mill 5 affect the longitudinal temperature distribution and wedge amount changes of the rough bar transported to the finishing mill 6. Furthermore, if the rolled material S is off-center during horizontal rolling by the roughing mill 5, the width reduction amount by the edger will differ between the work side and the drive side, affecting the change in the wedge amount in the longitudinal direction of the rough bar being transported to the finishing mill 6. This causes the wedge amount from the front to the tail end of the rolled material S to fluctuate, which affects the amount of meandering at the tail end of the rolled material S.

The performance data stored in the database unit 101 may be acquired as appropriate from the host computer 92, the control computer 91, or the control controller 90. Alternatively, a data acquisition unit 103 may be provided to collect this performance data, and the performance data may be temporarily stored in the data acquisition unit 103, and a data set in which multiple types of performance data are associated may be generated and then stored in the database unit 101. Since the data stored in the database unit 101 may be acquired at different times, it is possible to configure data sets in which the multiple types of performance data are associated with each other in the data acquisition unit 103.

The tail-end meandering amount prediction model generation unit 100 is preferably provided in the meandering amount prediction device 20. The tail-end meandering amount prediction model generation unit 100 can also be provided in the control computer 91, or in an independent computer capable of communicating with other devices. The tail-end meandering amount prediction model generation unit 100 may also be configured as a device separate from the database unit 101, using a device capable of receiving the data sets stored in the database unit 101. The database unit 101 stores 100 or more data sets. Preferably, 1,000 or more, and more preferably 10,000 or more data sets are stored in the database unit 101. The data stored in the database unit 101 may be screened as necessary.

The machine learning unit 102 uses the data set accumulated in the database unit 101 to generate a tail end meandering amount prediction model M that predicts the meandering amount of the tail end of the rolled material S at the entry side of the rolling stand F through machine learning using multiple learning data, including as input actual data the wedge amount identified by the entry wedge identification unit 21, the camber amount identified by the entry camber identification unit 22, and the camber amount identified by the exit camber identification unit 23, and the amount of meandering of the tail end of the rolled material S at the entry side of the rolling stand F as output actual data. The tail end meandering amount prediction model M may also be generated using as input actual data actual data on rolling operation parameters at the front end of the rolled material S, actual data on operation parameters related to temperature changes in the longitudinal direction of the rolled material S, and actual data on rolling operation parameters of the roughing mill 5.

Any machine learning model can be used to generate the tail end meandering amount prediction model M, as long as it provides sufficient prediction accuracy for the amount of meandering at the tail end for practical use. For example, commonly used neural networks (including deep learning and convolutional neural networks), decision tree learning, random forests, support vector regression, etc. can be used. An ensemble model combining multiple models can also be used. For example, the tail end meandering amount prediction model M can be generated by machine learning using a general neural network such as the one shown in Figure 12. In particular, deep learning does not require consideration of the problem of multicollinearity, and other operational parameters that are correlated with the amount of meandering at the tail end of the rolled material S can be freely selected as inputs, thereby improving the prediction accuracy for the amount of meandering at the tail end. For example, a neural network with two to three intermediate layers, three to five nodes, and a sigmoid function as the activation function can be used.

The machine learning unit 102 may improve the accuracy of estimating the tail end meandering amount by dividing the data set stored in the database unit 101 into training data and test data and performing learning on the data. For example, the machine learning unit 102 may use the training data to learn the weight coefficients of the neural network, and generate the tail end meandering amount prediction model M by appropriately changing the neural network structure (number of intermediate layers and number of nodes) so as to increase the accuracy rate of the tail end meandering amount in the test data. The weight coefficients can be updated using an error propagation method. Note that the tail end meandering amount prediction model M may be updated to a new model by re-learning, for example, every six months or once a year. This is because the more data stored in the database unit 101, the more accurate the tail end meandering amount can be predicted. By updating the tail end meandering amount prediction model M based on the latest data, it is possible to generate a tail end meandering amount prediction model that reflects changes in the manufacturing conditions of hot-rolled steel sheets manufactured using a hot rolling line.

As an example of the present invention, an example in which the present invention is applied to a finishing rolling mill consisting of seven rolling stands arranged in a hot rolling line will be described. In this example, the objective was to reduce the amount of meandering at the tail end of the rolled material S in the second rolling stand of the finishing rolling mill. Specifically, an entry wedge specifying unit 21 that specifies the wedge amount at the front end of the rolled material S at the entry side of the second rolling stand (rolling stand F2), an entry camber specifying unit 22 that specifies the camber amount at the front end of the rolled material S at the entry side of rolling stand F2, and an exit camber specifying unit 23 that specifies the camber amount at the front end of the rolled material S at the exit side of rolling stand F2 were arranged, constituting a meandering amount prediction device 20 having a tail end meandering amount prediction unit 24 as shown in FIG. 4. The entry wedge specifying unit 21 was equipped with thickness gauges arranged on the work side and drive side of the rolled material S, and determined the wedge amount at the front end of the rolled material S from the thickness data obtained from the thickness gauges. In addition, the entry camber identification unit 22 and the exit camber identification unit 23 use an area camera to capture an image of the planar shape of the leading edge of the rolled material S, and perform image processing on the captured image to identify the widthwise ends of the rolled material S, thereby identifying the widthwise center position of the rolled material S.

In this example, a low-carbon steel plate with a width of 1250 mm was used as the material S to be rolled. The entry thickness of the material S in rolling stand F2 of the finishing rolling mill was 20 mm, and the exit thickness was 13 mm. In this example, a zero point adjustment was performed in advance to ensure that the command leveling of rolling stand F2 was set appropriately, and the material S was then rolled. The wedge amount and camber amount at the leading edge of the material S were determined as the leading edge of the material S passed through rolling stand F1 and reached rolling stand F2. The camber amount at the leading edge of the material S was also determined as the leading edge of the material S passed through rolling stand F2 and reached rolling stand F3. As a result, the wedge amount at the leading edge of the material S at the entry side of rolling stand F2 was 0.05 mm. In addition, the camber amount at the tip of the rolled material S at the entry side of rolling stand F2 was 0 mm, and the camber amount at the tip of the rolled material S at the exit side of rolling stand F2 was -20 mm.

Then, the tail end meandering amount prediction unit 24 predicted the meandering amount of the tail end of the rolled material S in the rolling stand F2. In predicting the meandering amount of the tail end of the rolled material S, a leveling estimation step was performed to estimate an estimated leveling value _Sd at the front end of the rolled material S using formula (5). As a result, the estimated leveling value _Sd was −0.35 mm. Then, a meandering amount estimation step was performed to predict the meandering amount _yc of the tail end of the rolled material S using formula (11). As a result, the meandering amount _yc was predicted to be −28 mm. Meanwhile, by using the inlet camber determination unit 22, the width direction center position of the tail end of the rolled material S could also be determined, and the determined meandering amount of the tail end of the rolled material S was −25 mm. This confirmed that the meandering amount of the tail end of the rolled material S can be predicted with high accuracy by the meandering amount prediction device 20 of this embodiment.

Next, an example of meandering amount control for reducing the amount of meandering at the tail end of a rolled material S of the same dimensions will be described. In this example, a meandering amount control device 40 is provided, and the meandering amount _yc of the tail end of the rolled material S predicted by the meandering amount prediction device 20 installed in the rolling stand F2 is received, and a leveling set value is sent to the control controller 90 as a command value for the reduction device of the rolling stand F2. In this case, the leveling set value calculation unit 41 calculates a leveling set value for reducing meandering at the tail end of the rolled material S, and the leveling set unit 42 sends a control command to the control controller 90 to set the leveling set value while the steady portion of the rolled material S is being rolled in the rolling stand F2.

Table 1 shows an example of controlling the amount of meandering at the tail end of the rolled material S using this embodiment. In the example shown in Table 1, the wedge amount at the front end of the rolled material S at the entry side of rolling stand F2 was 0.05 mm, the entry-side camber amount at the front end of the rolled material S was 0 mm, and the exit-side camber amount was -21 mm. In this case, the meandering amount prediction device 20 predicted the amount of meandering at the tail end of the rolled material S to be -30 mm. However, the leveling set value calculation unit 41 had previously set the limit meandering amount to an absolute value of 10 mm, and since the predicted meandering amount exceeded the limit, the leveling setting was determined to be 0.06 mm. Then, the leveling setting unit 42 set the leveling set value calculated while rolling the steady portion of the rolled material S in rolling stand F2, and performed tailing of the tail end of the rolled material S. The meandering amount at the tail end of the rolled material S was found to be a satisfactory -5 mm.

Meanwhile, Table 1 also shows a comparative example in which control of the amount of meandering at the tail end of the rolled material S was not performed. In the comparative example, the wedge amount at the front end of the rolled material S at the entry side of rolling stand F2 was 0.03 mm, the entry-side camber amount at the front end of the rolled material S was -1 mm, and the exit-side camber amount was -19 mm. In the comparative example, because control of the amount of meandering at the tail end of the rolled material S was not performed, the leveling setting value was set to 0 mm, and rolling was performed with the preset command leveling. As a result, the amount of meandering at the tail end of the rolled material S was -24 mm, which was larger than in the example. From the above, it was confirmed that this example can effectively reduce the amount of meandering at the tail end of the rolled material S.

The above describes an embodiment of the invention developed by the inventors, but the present invention is not limited to the descriptions and drawings that form part of the disclosure of the present invention according to this embodiment. In other words, all other embodiments, examples, and operational techniques that are developed by those skilled in the art based on this embodiment are included within the scope of the present invention.

1 Hot rolling line 2 Heating furnace 3 Descaling device 4 Width reduction press device 5 Roughing mill 6 Finishing mill 7 Cooling device 8 Coiler (winder)
REFERENCE SIGNS LIST 10 Entry-side transport roll 11 Exit-side transport roll 12 Inter-stand looper 20 Meandering amount prediction device 21 Entry-side wedge identification unit 22 Entry-side camber identification unit 23 Exit-side camber identification unit 31 Wedge meter 32 Entry-side camera 33 Exit-side camera 40 Meandering amount control device 41 Leveling set value calculation unit 42 Leveling setting unit 61a, 61b Work rolls 62a, 62b Backup rolls 63, 63a, 63b Bearing box (backup roll chock)
64, 64a, 64b Housing 65, 65a, 65b Load cell 66, 66a, 66b Screw down device 90 Control controller 91 Control computer 92 Host computer F, F1 to F7 Rolling stand PL Pass line S Rolled material

Claims (6)

A meandering amount prediction device for a rolled material that predicts the meandering amount of a tail end portion of a rolled material in a rolling stand that constitutes a hot finishing rolling mill, comprising:
an inlet wedge specifying unit that specifies a wedge amount of the tip end of the rolled material at the inlet side of the rolling stand;
an entry camber specifying unit that specifies the amount of camber at the tip end of the rolled material at the entry side of the rolling stand;
an outlet camber specifying unit that specifies the amount of camber at the tip end of the rolled material at the outlet side of the rolling stand;
a tail end meandering amount prediction unit that predicts the amount of meandering of the tail end of the material to be rolled in the rolling stand, using the wedge amount of the front end of the material to be rolled specified by the entry-side wedge specifying unit, the camber amount of the front end of the material to be rolled specified by the entry-side camber specifying unit, and the camber amount of the front end of the material to be rolled specified by the delivery-side camber specifying unit;
A device for predicting the meandering amount of a rolled material, comprising: a leveling set value calculation unit that calculates a leveling set value of the rolling stand based on the meandering amount of the tail end portion of the rolled material predicted by the rolled material meandering amount prediction device according to claim 1;
a leveling setting unit that sets the leveling of the rolling stand based on the leveling set value calculated by the leveling set value calculation unit during rolling of the steady portion of the rolled material;
A meandering amount control device for a rolled material comprising: A method for predicting the meandering amount of a rolled material, the method comprising:
an inlet wedge specifying step of specifying a wedge amount of the tip end portion of the rolled material at the inlet side of the rolling stand;
an entry camber specifying step of specifying a camber amount of a leading end portion of the rolled material at the entry side of the rolling stand;
an outlet camber specifying step of specifying a camber amount of a leading end portion of the rolled material at the outlet side of the rolling stand;
a tail end meandering amount prediction step of predicting a meandering amount of the tail end of the material to be rolled in the rolling stand using the wedge amount of the front end of the material to be rolled specified in the entry-side wedge specifying step, the camber amount of the front end of the material to be rolled specified in the entry-side camber specifying step, and the camber amount of the front end of the material to be rolled specified in the delivery-side camber specifying step;
A method for predicting the amount of meandering of a rolled material, comprising: The method for predicting the meandering amount of a rolled material according to claim 3, wherein the tail end meandering amount prediction step includes a step of predicting the meandering amount of the tail end of the rolled material in the rolling stand using a tail end meandering amount prediction model trained by machine learning, which includes as input the wedge amount of the tip end of the rolled material identified in the entry wedge identification step, the camber amount of the tip end of the rolled material identified in the entry camber identification step, and the camber amount of the tip end of the rolled material identified in the delivery camber identification step, and outputs the meandering amount of the tail end of the rolled material in the rolling stand. a leveling set value calculation step of calculating a leveling set value of the rolling stand based on the meandering amount of the tail end portion of the rolled material predicted by the method for predicting the meandering amount of the rolled material according to claim 3 or 4;
a leveling setting step of setting the leveling of the rolling stand based on the leveling set value calculated in the leveling set value calculation step while rolling the steady portion of the rolled material;
A method for controlling the amount of meandering of a rolled material, comprising: A method for manufacturing a metal strip, comprising the step of manufacturing a metal strip using the method for controlling the meandering amount of a rolled material described in claim 5.