JP6663872B2 - Rolling mill control device, rolling mill control method, and rolling mill control program - Google Patents

Description

  The present invention relates to a control device for a rolling mill, a control method for a rolling mill, and a control program for a rolling mill.In particular, a control device for a rolling mill suitable for suppressing a thickness variation caused by a variation in hardness of a base material, The present invention relates to a method for controlling a rolling mill and a control program for a rolling mill.

  A rolling mill is known as a plant that efficiently produces thin metal materials. In this rolling mill, a plurality of rolling stands are arranged and rolled in order, or, by rolling back and forth with one rolling stand repeatedly, the material to be rolled is gradually rolled to adjust to a desired thickness. .

  In general, based on the detection result of the thickness gauge provided on the exit side of the rolling stand, by controlling the rolling force applied to the material to be rolled or the tension applied to the material to be rolled, a desired thickness is obtained. Adjust to a value. There is a so-called monitor control as one of control methods for obtaining a desired plate thickness. In this monitor control, integral control is performed based on the measurement value of the exit thickness gauge. Such a technique is described in, for example, JP 2013-193102 A (Patent Document 1).

JP 2013-193102 A

In a rolling mill that is a plant that efficiently produces a thin metal material, a sheet thickness defect due to uneven hardness of a material to be rolled may occur. Hardness unevenness refers to the case where the hardness (deformation resistance) of the material to be rolled is not uniform. If there is unevenness in the hardness in the longitudinal direction (rolling direction), the material to be rolled is crushed differently, so the thickness at the exit side of the rolling mill. Thickness fluctuation occurs.
By the integral control based on the detection result of the thickness gauge, the thickness deviation on the output side is usually kept close to 0. However, when disturbances other than the thickness on the entrance side such as unevenness in hardness of the material occur, the thickness deviation Occurs. For example, if there is a high hardness part, rolling must be performed by strongly tightening the reduction, but the high hardness part will remain as a high hardness part in the next rolling, and the unevenness in hardness will be caused by multiple rolling. Continue to remain after.

  In particular, when the disturbance continues to change in a ramp shape or over time, the deviation cannot be completely removed by the integral control, and a certain offset remains in the delivery side plate thickness during that time.

  As described above, in the related art, it is difficult to remove the thickness deviation due to the uneven hardness because the variation in deformation resistance is not considered.

  An object of the present invention is to provide a control device of a rolling mill, a control method of a rolling mill, and a control program of a rolling mill capable of removing a thickness deviation caused by uneven hardness.

  In order to achieve the above object, in the present invention, a continuous rolling mill configured by several rolling mills, or a reverse rolling mill that performs rolling a plurality of times in a specific rolling mill, The hardness information is calculated and stored in the hardness data table based on the load applied to the material to be rolled by the rolls at a predetermined pass or at a predetermined level, in correspondence with the position information corresponding to the longitudinal length of the material to be rolled. And a roll gap that is an interval between the rolls based on hardness unevenness information read from the hardness data table in accordance with a rolling position in a pass after the predetermined pass or a stage after the predetermined stage. Is configured to have a control unit for controlling.

  Alternatively, the rate of change in hardness unevenness is predicted from the rolling result of the preceding stand of tandem rolling or the preceding pass of reverse rolling, a correction amount capable of canceling the rate of change in integral control is calculated, and the subsequent pass of the latter stand or reverse rolling is calculated. Correction is made to the integral control of.

  Further, a minimal offset due to an error in the prediction control can be removed by a correction output by the double integrator.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress the influence which it has on the delivery side plate thickness by hardness unevenness.

The figure which shows the example of a control structure of the single stand rolling mill to which this invention is applied. The figure which shows the outline of the entrance side thickness control device 20 and the new exit side thickness control device 51. The figure which shows the mode of the rolling performed between upper and lower work rolls. Diagram showing the outline of application of the present invention in a reversible rolling mill The figure which shows calculation and storage of the hardness unevenness coefficient using the transfer process of a state quantity. The figure which shows a hardness unevenness coefficient data table. The figure which shows extraction of the hardness unevenness coefficient from a data table. FIG. 4 is a control block diagram of the new-side sheet thickness control of the present invention.

  As an embodiment of the present invention, a case where the present invention is applied to a single stand rolling mill including one rolling mill, an entrance tension reel, and an exit tension reel as shown in FIG. 1 will be described.

  FIG. 1 shows a control configuration of a single stand rolling mill. The single-stand rolling mill has an input side TR (tension reel) 2 on the input side and an output side TR3 on the output side with respect to the rolling direction of the rolling mill 1 (from left to right in the case of this drawing). After the material to be rolled out from the entrance TR2 is supplied to the rolling mill 1 via the rollers 210 and rolled, it is wound up on the exit TR3 via the rollers 211. The rolling mill 1 includes an upper work roll 121A, a lower work roll 121B, an upper intermediate roll 122A, a lower intermediate roll 122B, an upper backup roll 123A, and a lower backup roll 123B from the rolled material 30 side with the rolled material 30 interposed therebetween. Then, by changing the roll gap between the upper and lower work rolls, the roll gap control device 7 for controlling the thickness of the material to be rolled and the mill speed control for controlling the speed of the rolling mill 1 The device 4 is installed. The entrance TR2 and the exit TR3 are driven by an electric motor, and an entrance TR controller 5 and an exit TR controller 6 are provided as devices for driving the electric motor and the electric motor.

  The functions shown in each block in the control configuration of the single stand rolling mill shown in FIG. 1 may be configured as a program executed by a computer. In this case, the function described as each “... Device” is stored as software in a storage area of the computer and executed by the computer. The control of the single-stand rolling mill shown in FIG. 1 can be executed by one computer, and can be executed in a distributed manner by a plurality of computers.

  During rolling, a speed command is output from the rolling speed setting device 10 to the mill speed control device 4, and the mill speed control device 4 performs control such that the speed of the rolling mill 1 is kept constant. On the entry side and the exit side of the rolling mill 1, rolling is performed stably and efficiently by applying tension to the material to be rolled. The entrance tension setting device 11 and the exit tension setting device 12 calculate the tension required for that purpose. Based on the input and output tension set values calculated by the tension setting devices 11 and 12, a current value for obtaining a motor torque required to apply the set tension to the material to be rolled is converted to an input tension current conversion device 15 Further, it is obtained by the output side tension current converter 16 and provided to the input side TR controller 5 and the output side TR controller 6. The entry side TR control device 5 and the exit side TR control device 6 control the motor current so as to be a given current, and a predetermined value is applied to the material to be rolled by the motor torque applied to the entry side TR2 and the exit side TR3 from the motor current. Give tension.

  The input-side tension current converter 15 and the output-side tension current converter 16 calculate a current set value (a motor torque set value) to be a tension set value based on a model of the TR mechanical system and the TR control device. Since the model includes an error, the actual tension measured by the entrance tension meter 8 and the exit tension meter 9 installed on the entrance side and the exit side of the rolling mill 1 are used to control the entrance tension control device 13 and the exit side. The tension control device 14 corrects the tension set value and applies the correction to the input-side tension current converter 15 and the output-side tension current converter 16 to set the current value to be set in the input TR controller 5 and the output TR controller 6. To change.

  Further, since the thickness of the material to be rolled is important in terms of product quality, the thickness is controlled. The sheet thickness on the delivery side of the rolling mill 1 is determined by the new delivery side thickness control device 51 based on the actual thickness (thickness deviation) detected by the delivery side thickness gauge 17 to determine the roll gap of the rolling mill 1. It is controlled by using and operating. In addition, the sheet thickness on the entry side of the rolling mill 1 is controlled by the entry-side sheet thickness control device 20 from the actual sheet thickness (sheet thickness deviation) detected by the entry-side sheet thickness gauge 19 so that the exit-side sheet thickness of the rolling mill is constant. It is controlled by operating the roll gap of the rolling mill 1 using the roll gap control device 7.

  Here, in the case where unevenness in hardness, which is a change in deformation resistance of a material to be rolled in a single-stand rolling mill, occurs, a control method for minimizing a thickness variation caused by unevenness in hardness will be examined.

Rolling is performed by crushing the material to be rolled between upper and lower work rolls, as shown in FIG. At this time, the rolled material 30 is pulled by the entry side tension T _b and outgoing side tension T _f, gap between the upper and lower work rolls is determined by the (roll gap) S, entry side by being crushed by the rolling load P The thickness H is the delivery side plate thickness h. At the same time, the rolling speed causes the incoming plate speed to be lower than the work roll speed, and the outgoing plate speed to be higher. In the case of the work roll speed V _R, the entry-side speed V _e and exit-side speed V _o. A work roll speed V _R, the relationship of the inlet-side velocity V _e and the exit-side speed V _o, as shown in FIG. 3, can be expressed using the forward slip f and the reverse ratio b.

FIG. 2 shows an outline of the entry-side plate thickness control device 20. The entry-side sheet thickness control device 20 performs a transfer processing operation 201 on the entry-side sheet thickness deviation ΔH (deviation between the target sheet thickness and the actual sheet thickness) measured by the entry-side sheet thickness gauge 19 to a position immediately below the rolling mill 1, and The feedforward control is performed by multiplying the thickness deviation and the roll gap conversion gain Q / M 202 and the control gain G _FF 203, and the control output is output to the roll gap control device 7 of the rolling mill 1. Here, T _FF is the time obtained by subtracting the control delay of the entry side thickness control from the transfer time from the entry side thickness gauge to immediately below the mill, and the block of e- ^T _FF ^{* S} indicates the measured value of the entry side thickness gauge This is the process of transferring to immediately below.

In the new delivery side thickness control 51, the delivery side thickness deviation Δh (deviation between the target thickness and the actual thickness) measured by the delivery side thickness gauge 17 is added to the conversion gain (M + Q) Feedback control for integrating by _multiplying / M and control gain G _FB is performed as main control.

  On the other hand, the cold-rolled material may have uneven hardness depending on the manufacturing process in the upper process, and the change in hardness of the material is one of the disturbances in the rolling phenomenon, and the material is rolled under the same pressure. However, the thickness of the product on the delivery side varies. When the slab after hot rolling is cooled, supports are arranged at regular intervals, and the temperature drop speed is high at the point of contact with this support, and the temperature unevenness occurs compared to the place where it does not, resulting in a high hardness part May come. This temperature unevenness appears as a long-period, ramp-shaped disturbance in a cold-rolled material coil in several places within one coil, and monitor control causes a certain offset in the exit side plate thickness. Has become.

  Rolling is performed with the aim of rolling the plate thickness to a certain target plate thickness, so if there is unevenness in the hardness of the material, the places with high hardness should be rolled by tightening the reduction more strongly to increase the thickness And For this reason, a portion having a high hardness remains as a portion having a high hardness even in the next rolling, and the hardness unevenness of the material continues to remain after a plurality of rollings.

  Therefore, in the new delivery side sheet thickness control 51, in addition to the feedback control for integrating based on the delivery side sheet thickness deviation Δh, the unevenness of the hardness of the material is detected, and the correction control of the sheet thickness control to be used for the next and subsequent rollings is performed.

  As this correction control, since the reversible rolling mill switches the rolling direction and performs rolling a plurality of times, when the rolling is performed from left to right in the nth pass as shown in FIG. The outline of control when rolling is performed from right to left will be described.

  At the time of rolling in the n-th pass in FIG. 4, in order to use the information of the hardness unevenness obtained by the rolling in the n-th pass in the (n + 1) -th pass, an n-th pass hardness unevenness variation data table 506-2 is prepared. In the n-th pass, hardness unevenness variation data is calculated and stored in the n-th pass hardness unevenness variation data table 506-2 together with the position of the coil wound on the output side TR3.

  In the (n + 1) th pass, hardness unevenness variation data is extracted from the nth pass hardness unevenness variation data table 506-2 according to the position of the coil unwound from the delivery side TR3, and the thickness control is corrected. At this time, an n + 1-th pass hardness unevenness variation data table 506-2 is created on the entry side TR2 at the same time for use in the (n + 2) -th pass. Accordingly, in the second and subsequent passes except for the first pass, it is possible to correct the thickness control using the hardness variation data of the previous pass.

  In order to correct the thickness control in the n-th pass, in the (n-1) -th pass, the hardness non-uniformity variation data table 506-1 is stored in the n-1 th pass non-uniformity variation data table 506-1 along with the rolling operation in the (n-1) th pass. The fluctuation data is stored.

  Here, the n-1th pass hardness unevenness variation data table 506-1, the nth pass hardness unevenness variation data table 506-2, and the n + 1th pass hardness unevenness variation data table 506-3 are collectively referred to as hardness unevenness variation data. It is called a table 506. In the hardness unevenness variation data table 506, the (n-1) th pass, the nth pass, and the (n + 1) th pass are representative data tables, and the hardness unevenness variation data table before the (n-1) th pass, A hardness unevenness variation data table after the +1 pass is also stored as needed.

  Hereinafter, a method of creating the hardness unevenness variation data table and a method of using the thickness variation control for correction will be described in detail.

  FIG. 8 shows a control configuration of the new-side sheet thickness control device 51.

In the new delivery side thickness control 51, the delivery side thickness deviation Δh measured by the delivery side thickness gauge 17 is input, the disturbance correction amount Δh _int is added, and the product calculation unit 512 calculates the delivery side thickness deviation to the roll gap. Is multiplied by the conversion gain (M + Q) / M, the control gain G _FB is multiplied by the product calculation unit 513, T _PLC / _TD is multiplied by the product calculation unit 514, and double integration is performed by the feedback control unit 515. Feedback control for integration processing is performed, and a roll gap control amount ΔS _MN is calculated. Further, the roll gap control amount ΔS _MN and the roll gap correction amount Δs _Q are added and output to the roll gap control device 7 of the rolling mill 1 as an output value of the new-side sheet thickness control 51. The roll gap control device 7 performs control such that the actual roll gap matches the control command value received from the entry-side thickness control device 20 and the new-out-side thickness control device 51. The variation in the exit side thickness of the rolling mill 1 cannot be detected immediately below the rolling mill 1 at the position where the variation occurs, and is detected by the exit side thickness gauge 17 installed at a position away from the rolling mill 1. There is a dead time until detection. Therefore, the feedback control is usually an integral control.
In integral control, the response speed at which the actual value approaches the target value increases as the integral gain G _FB increases, but when it is set to 0.4 or more, the actual value overshoots or undershoots the target value and returns. As a result, it takes time as a result. For this reason, setting the gain to about 0.3 provides a stable and high response.

  The hardness unevenness estimation unit 504 and the hardness unevenness variation data storage / output unit 505 in the hardness unevenness estimation device 50 will be described with reference to FIGS.

The hardness unevenness estimation unit 504 estimates the hardness unevenness of the material based on the variation in deformation resistance. Equation (1) as the variation follows the uneven hardness coefficient K (x) indicating the in deformation resistance k _m (x) at position x of the coil wound on the outlet side TR3, defined. Here, km _{, n} : Average deformation resistance based on n-pass rolling settings.

As an expression for obtaining the rolling load, k _m: Mean deformation resistance ^{(kN / mm 2), b} : plate width (mm), R ': a flat work roll radius (mm), Q _P: correction term by tension, D _P: Equations using the friction coefficient, the correction term relating to the rolling reduction, and P: rolling load (kN) are as shown in Equation 2.

Here, as shown in Equation 3, in the same rolling, the input / output tension, the coefficient of friction, the reduction (rate), and the sheet width are assumed to be constant, and the rolling load and the deformation resistance (hardness unevenness of the material) are considered to be proportional. .

As a result, the hardness unevenness coefficient K (x) is calculated based on the rolling load _Pn based on the n-pass rolling setting and the load P (x) at the position x of the coil wound on the delivery side TR3 as shown in Expression 4. Then, the calculation can be performed by the following equation.

  When there is a load meter in the equipment, calculation can be performed using the actual load. However, when there is no load meter, the actual load is estimated by the load estimating unit 502 in FIG. In the load estimating unit 502, the value of the roll gap of the mill measured by the roll gap measuring device 54 is transferred by the transfer processing device 501 to the position of the exit thickness gauge. In the load estimating unit 502, based on the roll gap s transferred, the mill constant M determined by the equipment and the roll, and the exit thickness deviation Δh measured by the exit thickness gauge 17, the load P is calculated by the following equation (5). (x) is derived. Here, href indicates a set value (mm) of the delivery side thickness gauge.

Further, by using the measured value ΔH of the inlet thickness gauge and the measured value Δh of the outlet thickness gauge transferred to the position of the outlet thickness gauge that has been transferred to the hardness unevenness estimating unit 504 in the transfer processing device 503, , D _P : Correction term relating to friction coefficient and rolling reduction, R ': Deformation resistance can be derived in consideration of the amount of change in flat work roll radius (mm).

  The hardness unevenness variation data storage unit / output unit 505 has a function of storing the hardness unevenness variation data as a function (1), and is used by the correction circuit at the time of rolling in the next pass. The hardness unevenness coefficient K (x) is calculated based on the resistance.

  FIG. 5 shows a hardness unevenness variation data table 506. In the hardness unevenness variation data table 506, a storage area for the coil position x, a storage area for the hardness unevenness coefficient K (x), and a storage area for the hardness unevenness coefficient differential value dK (x) / dx are associated with each pass. And a storage area for a ramp-shaped disturbance occurrence section flag f (x).

  The calculated hardness unevenness coefficient K (x) is linked to the position x of the coil wound on the output side TR3 obtained by the output side tension reel turn number calculation device 53, and is calculated for each path as shown in FIG. A hardness unevenness variation data table 506 is created. The output side tension reel turn number calculation device 53 calculates the number i of turns of the tension reel based on the detection value of the rotation detector of the motor of the output side TR3. Based on the number of turns i, the position x of the coil wound around the output side TR3 can be calculated by the following equation (6).

Here, D _O : coil outer diameter (mm), DI: coil inner diameter (mm), h _n : outlet plate thickness of the nth pass (mm), L _{DTR ~ MILL} : distance from MILL to outlet TR (m) ), X: indicates the position (m) of the coil wound around the output side TR.
The hardness unevenness coefficient K (x), the hardness unevenness coefficient differential value dK (x) / dx, and the ramp-shaped disturbance occurrence section flag f (x) stored in the hardness unevenness variation data table 506 are based on the following equation (7). Perform the operation. The calculation of the data to be stored in the table is performed every time the position of the coil wound on the output side TR advances by Δx m. The ramp-type disturbance occurrence section flag f (x) is based on the differential value dK (x) / dx of the hardness unevenness coefficient, which is the amount of change in the hardness unevenness coefficient per meter, when the threshold value TH is exceeded. The determination is made as a section in which a ramp-shaped disturbance has occurred.

  Next, the hardness unevenness variation data storage / output unit 505 will be described with reference to FIG.

  The hardness unevenness variation data storage / output unit 505 has an output function of hardness unevenness variation data as a function (2), and is unwound from the delivery side TR3 from the hardness unevenness variation data table 506 created in the previous pass. The position corresponding to the position x of the coil is read out, and the hardness unevenness coefficient K (x) and the ramp-shaped disturbance section occurrence flag f (x) are output to the new-side sheet thickness variation device 51. The output side tension reel turn number calculation device 53 calculates the number i of turns of the tension reel based on the detection value of the rotation detector of the motor of the output side TR3. The position x of the coil unwound from the output side TR is obtained by the following equation 8 based on the number i of turns of the output side TR as in the winding operation.

Here, H _{n + 1} : the thickness of the entrance side of the (n + 1) th pass, which is equal to the thickness of the exit side of the previous pass (the nth pass).

In FIG. 8, the new-side sheet thickness control device 51 has a hardness unevenness variation FF correction unit 511 and a ramp-shaped disturbance correction circuit 512 as a correction function for the hardness unevenness variation of the material. The new output side sheet thickness control device 51 calculates the roll gap operation amount Δs _MN based on the output side sheet thickness deviation Δh of the output side sheet thickness gauge 17 and the output Δh _int of the ramp-shaped disturbance correction circuit 512 to obtain a hardness unevenness FF correction unit. The output Δs _Q of 511 is added and output to the roll gap control device 7.

The hardness unevenness FF correction unit 511 calculates the GAP correction operation amount Δs _Q using the hardness unevenness coefficient K (x) detected in the previous pass in advance. As the rate of change of deformation resistance before path is taken over to the material of the subsequent pass, the deformation resistance at the position x of the coil is unwound from the delivery side TR3 k _m (x) is rolling (n + 1) Path Using the average deformation resistance km _{, n + 1} based on the setting, it is derived by the following equation (9).

At this time, the increase / decrease ΔP of the load due to the change in the deformation resistance can be calculated by the following expression 10 using the set load _{Pset, n + 1} based on the rolling setting of (n + 1) passes.

The relationship between the load, the delivery side plate thickness, and the mill gap can be expressed by a gauge meter equation of the following equation 11 using the mill constant M.

Rearranging the above equation into a form for calculating the delivery side plate thickness gives the following equation (12).

Here, the GAP operation amount Δs _Q for canceling the variation of the exit side plate thickness when the load resistance ΔP is generated due to the variation in the deformation resistance is obtained as Equation 13 by solving the above equation with Δh = 0. Can be

The GAP operation amount Δs _Q obtained in this way is added to the GAP operation amount ΔS _MN by the output side thickness control to correct the thickness variation due to the uneven hardness.

Next, the ramp-shaped disturbance correction circuit 512 will be described. The ramp-shaped disturbance correction circuit 512 integrates the measured value Δh of the exit side thickness gauge by the integration unit 5122, further processes the vertical limit unit 5123, and outputs the disturbance correction amount Δh _int .

  The ramp-shaped disturbance correction circuit 512 performs correction by a double integrator in a section in which a ramp-shaped disturbance due to hardness unevenness in which the ramp-shaped disturbance occurrence section flag f (x) from the hardness unevenness estimating device 50 becomes 1 is generated. Is output.

  The output using the double integrator is effective for removing the offset in the section where the disturbance changes like a ramp with a constant slope, but on the other hand, when the disturbance stops or a different change occurs. Itself becomes a control disturbance. If this amount is large, the control causes overshoot or undershoot, so that the output of the double integral term must be made to function as small as possible.

Here, as a countermeasure to prevent the output of the double integrator from acting as a disturbance in the control system to cause overshoot or undershoot of the thickness control, a ramp-shaped disturbance occurrence section flag f (x) is set. In the section where the value is 0, the output Δh ′ _int of the double integrator is set to 0 by the disturbance section outside reset circuit 5121. Further, in order to prevent the control from becoming unstable due to the output of the double integrator, an upper / lower limiter 5123 is provided for the final output amount Δh _int of the ramp-shaped disturbance correction circuit 512.

Δh ′ _int and Δh _int are calculated by the following equation (14). Here, x ₁ is the position of the ramp-like disturbance occurrence section flag f (x) is 0 or more x, which indicates the number of turns TR located in the unwinder side of generation starting position of the ramp-like disturbances . Max and min indicate the upper and lower limits of the upper and lower limit circuits.

As described above, the ramp disturbance correction circuit 512 calculates the correction term Δh _int using the double integrator based on the ramp disturbance occurrence section flag f (x) from the previous pass as described above, Is realized.

  In the present embodiment, the control configuration of the single stand rolling mill has been described as an example.However, in the tandem rolling mill, the gap between the work rolls of the subsequent stand may be controlled based on the rolling performance of the preceding stand. Of course.

Outgoing tension roll 3
Roll gap control device 7
Delivery side thickness gauge 17
Hardness unevenness estimation unit 50
New delivery side thickness control device 51
Hardness unevenness data table 506
Outgoing side tension roll turn number calculation device 53

Claims (11)

A continuous rolling mill configured by a plurality of rolling mills, or a rolling device configured as a reverse rolling mill that performs rolling a plurality of times with a specific rolling mill, wherein a roll is formed in a predetermined pass or a predetermined stage. A calculating unit that calculates hardness information and stores the calculated hardness information in a hardness data table based on a load applied to the material to be rolled, in accordance with position information corresponding to a longitudinal length of the material to be rolled; in the path or stage after said predetermined stage, and a control unit for controlling the roll gap is a gap of the roll based on the hardness unevenness information read in accordance with the rolling position from the hardness data table lamp by uneven hardness And a ramp-shaped disturbance correction circuit for correcting an offset error of the exit side plate thickness caused by the shape disturbance . In claim 1, the control device of the rolling mill control of the roll gap, characterized in that it is adapted to remove the influence of the uneven hardness. According to claim 1, wherein the output so as to remove the offset error of the side thickness performs double integration, rolling mill control apparatus characterized by comprising a control unit for controlling the roll gap based on the double integral .   2. The control device according to claim 1, wherein the hardness information is obtained based on a rolling load based on a rolling setting and an actual load. According to claim 4, wherein the hardness information, rolling mill control device which is a hardness unevenness factor based on the average deformation resistance.   2. The control of a rolling mill according to claim 1, wherein when the rate of change of the hardness information is larger than a predetermined value, an integrated value corresponding to a deviation between the target thickness and the actual thickness is used as an input side of the feedback control. apparatus. Based on the load applied to the material to be rolled by the roll in a predetermined pass or a predetermined step, the hardness unevenness information is calculated and stored in a hardness unevenness data table in accordance with the position information corresponding to the length from the tip, A continuous rolling mill composed of a plurality of rolling mills based on hardness unevenness information read from the hardness unevenness data table in accordance with a rolling position in a pass after the predetermined pass or in a stage after the predetermined stage. Or controlling the roll gap, which is the interval between the rolls in a rolling mill configured as a reverse rolling mill that performs a plurality of rolling in a specific rolling mill , offset error of the exit side plate thickness caused by a ramp-shaped disturbance due to uneven hardness. Control method of the rolling mill to correct the pressure. Based on the load applied to the material to be rolled by the roll in a predetermined pass or a predetermined step, the hardness unevenness information is calculated and stored in a hardness unevenness data table in accordance with the position information corresponding to the length from the tip, A continuous rolling mill composed of a plurality of rolling mills based on hardness unevenness information read from the hardness unevenness data table in accordance with a rolling position in a pass after the predetermined pass or in a stage after the predetermined stage. Or controlling the roll gap, which is the interval between the rolls in a rolling mill configured as a reverse rolling mill that performs a plurality of rolling in a specific rolling mill , offset error of the exit side plate thickness caused by a ramp-shaped disturbance due to uneven hardness. Control program for a rolling mill to be executed by a computer so as to correct the pressure. 2. The apparatus according to claim 1, further comprising a flag generation unit configured to generate a flag for controlling an operation of the ramp-shaped disturbance correction circuit based on the hardness unevenness information, wherein the ramp-shaped disturbance correction circuit executes the correction based on the flag. And a non-execution switch. The control method for a rolling mill according to claim 7, wherein a flag for determining the ramp-shaped disturbance is generated based on the hardness unevenness information, and the correction is switched between execution and non-execution based on the flag. 9. The control program according to claim 8, wherein a flag for determining the ramp-shaped disturbance is generated based on the hardness unevenness information, and the correction is switched between execution and non-execution based on the flag.

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