JP6750599B2 - Gauge meter Plate thickness error estimation method, plate thickness control method, rolled material manufacturing method, and plate thickness control device - Google Patents

Description

The present invention relates to a technique for rolling a metal plate to a target plate thickness by a rolling mill by gauge gauge type plate thickness control.

In a line where steel strips are continuously rolled, automatic strip thickness control is performed in order to keep the precision of the finished strip thickness within the tolerance.
The automatic strip thickness control includes, for example, feedback control (monitor AGC) that uses the deviation of the actual value of the strip thickness gauge installed on the delivery side of the rolling mill from the target value as a control input, gauge gauge type strip thickness control (gauge meter). AGC), feedforward control based on strip thickness deviation on the rolling mill entrance side, and the like. This plate thickness control is performed by changing the rolling load (roll-down control amount) and the inter-stand tension (tension control amount).

In the gauge meter type plate thickness control described above, the rolling mill itself is treated as a plate thickness gauge to perform plate thickness control. That is, the gauge meter type plate thickness control is based on the measured values of the roll opening S and the rolling load P, and the gauge meter which is the plate thickness immediately after leaving the roll gap is calculated from the gauge meter formula represented by the following formula. The roll opening is operated by estimating Δh from the reference value of the plate thickness h. In the gauge meter type plate thickness control, the rolling load is changed with the roll opening S as an operation amount to adjust the plate thickness.
h=S+(P/M)
Or Δh=ΔS+(ΔP/M)
Here, M is a mill rigidity coefficient.

Further, Δh=h ₀ −h, ΔS=S ₀ −S, ΔP=P ₀ −P, and h ₀ , S _O , and P ₀ are reference values set in advance.
The deviation term Δd is added to the gauge meter equation as in the following equation to improve the accuracy of sheet thickness estimation.
Δh=ΔS+(ΔP/M)+Δd
Further, there is a plate thickness control method described in Patent Document 1 as a conventional technique for improving the accuracy of plate thickness control. In this thickness control, the output side thickness deviation is expressed by a linear sum of the input side thickness deviation and the control amount deviation, and the Kalman filter is applied to the input side thickness deviation and the control amount deviation to obtain the output side thickness deviation. Calculate the entrance side plate thickness influence coefficient and the control amount influence coefficient that minimize. Then, by correcting (sequentially updating) the entrance side thickness influence coefficient and the control amount influence coefficient, the estimation accuracy of the thickness deviation is improved. Here, in the case of calculating the above-mentioned inlet side plate thickness influence coefficient and control amount influence coefficient, when controlling with the reduction amount, the control amount becomes the reduction control amount. Further, in the case of controlling by both the tension and the reduction amount, the control amount is the tension control amount and the reduction control amount.

JP 61-193716A

The deviation term Δd added to the gauge meter formula is expressed by, for example, a fixed function with tension as a variable, but the gauge meter plate thickness is a disturbance caused by differences in the amount of rolling oil sprayed or the deformation resistance of rolling material. Affected by ingredients. Therefore, it is assumed that the plate thickness cannot be accurately estimated by the conventional deviation term using the fixed function, and there is a possibility that the plate thickness deviation due to the line speed acceleration/deceleration may remain. At this time, it is possible to suppress deviation from the tolerance by combining with feedback control, but since there is a conveyance delay of the material to be rolled to the thickness gauge on the exit side of the rolling mill, deviation from the thickness deviation that occurs at the moment of acceleration/deceleration Cannot be canceled.

Further, in the method of Patent Document 1, since the timing difference between the time of estimating the sheet thickness deviation (time-varying step) and the time of observing the sheet thickness deviation (innovation step) due to the conveyance delay of the material to be rolled is not considered, the conveyance time It may not be possible to deal with cases in which the change in
The present invention has been made paying attention to the above points, and in the gauge meter type plate thickness control, it is possible to suppress the plate thickness accuracy error even if there is a sharp change in the line speed. The purpose is to provide.

In order to solve the problem, one aspect of the present invention, when determining the gauge meter plate thickness of the rolling mill exit side from the roll opening of the rolling mill for rolling the material to be rolled and the measured value of the rolling load. The roll gauge of the rolling roll of the rolling mill, the tension of the material to be rolled on the rolling mill entrance side, and the tension of the material to be rolled on the rolling mill exit side, the gauge meter for the true plate thickness It is characterized in that the plate thickness error of the plate thickness is estimated.

According to one aspect of the present invention, when estimating the plate thickness error, the roll peripheral speed, by using each tension of the material to be rolled on the rolling mill entrance side and exit side as variables, a steep line speed change Even if there is, it is possible to suppress the influence on the plate thickness error. As a result, it is possible to improve the accuracy of the plate thickness control by accurately estimating the plate thickness immediately below the delivery side of the rolling mill.

It is a figure explaining the control method which concerns on embodiment based on this invention. It is a figure which shows the relationship with a line speed when board|plate thickness error is calculated|required from tension. It is a figure explaining the apparatus structure concerning the embodiment based on this invention. It is a figure explaining the result of an Example.

Next, an embodiment of the present invention will be described with reference to the drawings.
<Plate thickness control method>
First, the plate thickness control method of this embodiment will be described with reference to FIG.
The gauge meter plate thickness h _GM is expressed by the following gauge meter formula (1).
h _GM =S+(P/M) (1)
When the gauge meter plate thickness h _GM is represented by the deviation Δh _GM from the reference value h _GM0 , the gauge meter formula is represented by the following formula.
Δh _GM =ΔS +(ΔP/M)
Here, the setting of the roll opening at the start of rolling is calculated in advance, and the roll opening setting and the observed rolling load at the moment when the material to be rolled 2 is bitten into the rolling mill 1 are the reference values (also referred to as lock-on values). During rolling, the operation amount of the control system is calculated from the deviation from the lock-on value.

When the roll opening at lock-on (reference time) is S ₀ and the rolling load is P ₀ , the gauge meter plate thickness h _GM0 at lock-on is described below.
h _GM0 = S ₀ + P ₀ /M (2)
Then, from the formulas (1) and (2), the deviation Δh _GM of the gauge meter plate thickness h _GM from the standard gauge meter plate thickness h _GM0 is determined by the roll opening S and the observed rolling load P.
_{Δh GM = h GM - h GM0} = (S -S 0) + (P -P 0) / M
=ΔS+(ΔP/M)
Is expressed as
Here, when the target plate thickness is hr and the deviation Δhr of the target plate thickness hr from the reference gauge meter plate thickness h _GM0 is defined as the plate thickness target value, the plate thickness target value Δhr and the current gauge meter plate thickness deviation Δh The deviation Δhe from _GM is expressed by the following formula.
_{Δhe = (hr- h GM0) -Δh} GM = Δhr - Δh GM

Then, the thickness control is performed using the deviation Δhe from the target value of the gauge meter plate thickness, and the roll opening ΔS _r, which is the manipulated variable, is set by, for example, the following equation (3) (in FIG. 1, Reference numeral 22).
ΔSr=α・((M+Q)/M)・Δhe (3)
here,
Q: Plasticity coefficient,
α: gain (0 to 1)
Is.

In addition to the above control, the manipulated variable ΔSr can be determined by a general-purpose control system such as PID control. Further, a plate thickness gauge such as an X-ray plate thickness gauge is installed at a place slightly away from the rolling mill 1 on the output side of the rolling mill 1, and feedback control based on the true value of the plate thickness is configured by PI control or the like. There is also feedback control in which the roll opening of the rolling mill 1 is operated based on the deviation between the target value and the actual plate thickness value. This feedback control includes dead time, and since the feedback is based on the true value (measured value) of the plate thickness, a control system mainly composed of integration is often constructed.
The control system of the present embodiment is a model (error estimation) that estimates the difference (plate thickness error) between the plate thickness estimation value (h _GM0 +Δh _GM ) immediately below the work roll 1 a due to the gauge meter plate thickness and the true plate thickness. Equation) is set, and the estimated plate thickness error is reflected in the plate thickness control.

Next, a method for estimating the plate thickness error (error of gauge meter plate thickness) will be described.
Assuming that the gauge thickness error of the gauge meter plate thickness is Δd and the true plate thickness is h, the plate thickness error Δd is described below.
Δd=h−h _GM =h−(S+P/M)
This equation can be replaced with the following equation.
h=h _GM +Δd=S+P/M+Δd
Further, the deviation Δh of the true plate thickness h from the reference gauge meter plate thickness h _GM0 can be expressed by the following equation (4). Then, Δh obtained by the equation (4) is used as Δhe in the equation (3) (see reference numerals 21 and 22 in FIG. 1).
Δh = Δh _GM + Δd
= Δs + ΔP/M + Δd (4)
If the plate thickness error Δd can be estimated by some method, the accuracy of the gauge meter plate thickness estimation, which is the plate thickness estimation immediately below the plate thickness, is improved, and the plate thickness control accuracy using the gauge meter formula is improved.

In the present embodiment, the plate thickness error Δd is represented by an error estimation formula such as formula (5).
Δd=a×ΔMRH+b×ΔTui+c×ΔTuo (5)
This error estimation formula is used to calculate the plate thickness error Δd between the deviation ΔMRH of the roll peripheral speed of the work roll 1a of the rolling mill 1 with respect to the preset reference roll peripheral speed and the rolling mill 1 entry side with respect to the preset reference inlet tension. Formula of linearly combining the deviation ΔTui of the tension of the material 2 to be rolled and the deviation ΔTuo of the tension of the material 2 to be rolled on the output side of the rolling mill 1 with respect to the preset reference output tension by the time-varying parameters a, b and c It is represented by.
Here, the preset reference roll peripheral speed ΔMRH0, the preset reference inlet tension ΔTui0, and the preset reference outlet tension ΔTuo0 are reference values. In this embodiment, each reference value is a value acquired at the time of lock-on.

By using the plate thickness error Δd as a function in which the roll peripheral speed and the tension are variables, it is possible to obtain an estimated value corresponding to the acceleration/deceleration of the conveyance speed of the material 2 to be rolled. Here, it has been conventionally known that there is a change in plate tension on the inlet side and the outlet side of a rolling mill as a cause of an error in the gauge meter plate thickness. However, as confirmed by the inventors, when the thickness error of the gauge meter plate thickness is estimated using only the inlet tension and the outlet tension as variables, the estimated thickness error changes significantly every time the line speed is changed. Then, the finding was obtained (see FIG. 2). Therefore, in this embodiment, the plate thickness error Δd is estimated by linear combination of line speeds in addition to tension. This is because it is considered that when the line speed changes, the dynamic friction coefficient between the plate thickness and the work roll 1a also changes, the load is also affected, and the plate thickness changes.

However, if fixed values are used as the coefficients a, b, and c, the estimation accuracy may not necessarily be good. Therefore, in the present embodiment, the coefficients a, b, and c are used as time-varying parameters, and the coefficients a, b, and c are sequentially estimated using the Kalman filter (see reference numeral 20 in FIG. 1 ). The coefficients a, b, and c may be optimized by using an optimization method other than the Kalman filter.
It is possible to improve the estimation accuracy of the plate thickness error by sequentially estimating (sequentially updating) the coefficients a, b, and c of the plate thickness error Δd using the Kalman filter. Furthermore, in this embodiment, the control is further improved by combining the dead time compensation of the actual thickness measurement and performing the thickness control while estimating the correct thickness immediately below the work roll 1a of the rolling mill 1.

In the present embodiment, by using the plate thickness measurement value hm on the delivery side of the rolling mill 1 as the observed value, the gauge meter plate thickness compensated by the plate thickness error Δd to which the coefficients a, b, and c sequentially estimated by the Kalman filter are applied. The Kalman gain is adjusted using the difference from the sheet thickness measurement value on the delivery side of the rolling mill 1 (see reference numeral 20 in FIG. 1). At this time, dead time compensation is performed on the measurement of the actual plate thickness value to estimate the plate thickness Δd(t-L) immediately below the work roll 1a of the rolling mill 1.
Below, the example of the application method is described.
The Kalman filter estimates [a b c ] ^T .

Let a, b, and c at time k be a(k), b(k), and c(k), and define the parameter vector θ(k) by the following equation.
θ(k)=[a(k) b(k) c(k)] ^T
The discrete state equation for parameter estimation is as follows.
θ(k+1)=θ(k)+b _p v(k)
y(k)=φ(k) ^T θ(k)+w(k)
Where φ(k) ^T =[ΔMRH(k) ΔTui(k) ΔTuo(k)]
y(k)=Δd(k)
Is.

Further, v(k) and w(k) define system noise variances σ _v ² and σ _w ² , respectively.
Here, the observed value y(k) is an estimated value on the outlet side of the rolling mill 1 because it is observed by the plate thickness gauge 5 installed at a position separated from the outlet side of the rolling mill 1 by a predetermined distance. There is a dead time for the meter plate thickness.
When the measurement position of the plate thickness gauge 5 is set to the plate thickness h _m (t) with respect to the plate thickness h(t) immediately below the rolling mill 1, the following relationship is established if the dead time L until observation is used.
_{h m (t) = h (} t-L)
As described above, there is a dead time in observing the estimated plate thickness error.
If the actual value Δdm(t) of Δd(t) and the plate thickness error Δd(t) immediately below the rolling mill 1 are used and the dead time is L, then Δd _m (t) = Δd(t-L)
Can be expressed as

Here, the ^dead time can be described as e ^{−Ls in the} transfer function (s is a Laplace operator), but can be described as a rational function by using an approximate polynomial of Pade, and can be expressed as a linear model. The dead time compensation is not limited to the Pade approximation. You may make it compensate using a well-known state prediction method.
The order of the rational function can be set from the first order, but if the Pade approximation is approximated by the third order, the order is as follows.

In this example, since it is a third-order system, the state equation has a third-order state quantity and can be expressed in the following format having a direct term.

When this is discretized, it will be described below.
x _p (k+1) =A _d x _p (k) +B _d u(k)
y _p (k)=C _d x _p (k) +D _d u(k)
Here, A _d , B _d , Cd, and D _d are coefficient matrices of the discretized state equation.
The expanded equation of state is
θ(k+1) = θ(k) +b _p v(k)
x _p (k+1) =A _d x _p (k) +B _d u(k)
=A _d x _p (k)+B _d d _m (k)
=A _d x _p (k)+B _d (φ(k) ^T θ(k) +w(k))
=A _d x _p (k)+B _d φ(k) ^T θ(k) +B _d w(k)
y _p (k) =C _d x _p (k) +D _d d _m (k)
=C _d x _p (k) +D _d (φ(k) ^T θ(k) +w(k))
=C _d x _p (k) +D _d φ(k) ^T θ(k) +D _d w(k)

Here, x^(k) is calculated in the following update step by the Kalman filter.
Is successively estimated as.
here,

である

Is

Estimated values (a^(k), b^(k), c^(k)) of parameters (a(k), b(k), c(k)) included in the estimated x^(k). Using,
The estimated value Δd^(k) of the plate thickness error Δd is estimated by the following formula.

By giving this as Δd in equation (4) and using it for plate thickness control while compensating (updating) the gauge meter plate thickness, the error of the gauge meter plate thickness can be minimized and the accuracy of the plate thickness control system is improved. To do.
That is, the Kalman filter can successively estimate the parameters a, b, and c for estimating the plate thickness error of the gauge meter plate thickness, and can eliminate the plate thickness error of the gauge meter plate thickness formula.
Further, in the present embodiment, the plate thickness error of the gauge meter plate thickness can be estimated based on the true plate thickness also by using the dead time compensation model. Further, since the error of the gauge meter plate thickness is estimated, the accuracy of the control system immediately below the rolling is directly improved, so that the compensation amount can be calculated without delay of dead time, and a high-speed response can be secured.

<Device>
Next, an example of a device configuration to which the plate thickness control method of the present embodiment is applied will be described with reference to FIG.
In the present embodiment, a case where a steel strip as the material to be rolled 2 is rolled by a rolling mill 1 having a plurality of stages will be described as an example.
Each rolling mill 1 includes a pair of work rolls 1a, a backup roll 1b, and a reduction device 6 for operating the work roll 1a gap of the work rolls 1a.

Further, on the exit side of the rolling mill 1, an exit side plate thickness measuring unit 5 for measuring the plate thickness of the steel strip (rolled material 2) is arranged. The exit-side plate thickness measuring unit 5 is composed of, for example, an X-ray plate thickness meter. The entrance-side plate thickness measuring unit and the exit-side plate thickness measuring unit 5 output the measured plate thickness detection information to the plate thickness control unit 10.
Further, an inlet side tension measuring section 3 and an outlet side tension measuring section 4 for measuring the tension of the steel strip 2 are provided on the inlet side and the outlet side of the rolling mill 1. The entrance-side tension measuring unit 3 and the exit-side tension measuring unit 4 are, for example, tension detecting rolls. The inlet side tension measuring unit 3 and the outlet side tension measuring unit 4 output the measured measured tension information to the plate thickness control unit 10.

A roll peripheral speed measuring unit 8 for measuring the roll peripheral speed of the work roll 1a of the rolling mill 1 is provided. The roll peripheral speed measuring unit 8 is composed of, for example, an encoder, and detects, for example, the number of rotations of the upper work roll 1a and outputs it to the plate thickness control unit 10.
The rolling load measuring unit including the rolling load measuring unit 7 that measures the rolling load of the rolling mill 1 is composed of, for example, a load cell, and outputs the measured load information to the plate thickness control unit 10.
The plate thickness control unit 10 includes a control start time information acquisition unit 10A, a gauge meter plate thickness calculation unit 10B, a plate thickness error estimation unit 10C, and a roll opening operation unit 10D.

The control start time information acquisition unit 10A stores each reference value for control at the time of lock-on at the start of control.
The gauge meter plate thickness calculating unit 10B calculates the gauge meter plate thickness based on the rolling load measured by the rolling load measuring unit 7.
The roll opening operation unit 10D is a control unit main body, and is based on a correction value obtained by correcting the gauge meter plate thickness calculated by the gauge meter plate thickness calculation unit 10B with the plate thickness error estimated by the plate thickness error estimation unit 10C. Operate the roll opening of 1.
The plate thickness error estimation unit 10C performs a process of estimating a plate thickness error of the gauge meter plate thickness calculated by the gauge meter plate thickness calculation unit 10B with respect to the true plate thickness.
The plate thickness error estimation unit 10C of the present embodiment estimates the plate thickness error from each measurement measured by the entrance tension measurement unit 3, the exit tension measurement unit 4, and the roll peripheral speed measurement unit 8 and the error estimation formula. ..

The error estimation formula is, as shown in the following formula, the plate thickness error Δd, the deviation ΔMRH of the roll peripheral speed of the work roll 1a of the rolling mill 1 from the preset reference roll peripheral speed, and the rolling with respect to the preset reference inlet tension. The deviation ΔTui of the tension of the material 2 to be rolled on the inlet side of the rolling mill 1 and the deviation ΔTuo of the tension of the material 2 to be rolled on the outlet side of the rolling mill 1 with respect to the preset reference outlet tension are time-varying parameters a, b, c. It is expressed by the formula linearly combined with.
Δd=a×ΔMRH+b×ΔTui+c×ΔTuo
Here, the preset reference roll peripheral speed MRH0, the preset reference entrance tension Tui0, and the preset reference exit tension Tuo0 are, for example, the values at the start of rolling of the target rolled material 2.
M is a mill rigidity coefficient. Delta] h ₌ h 0 -h, is _{ΔS = S 0 -S, ΔP =} P 0 -P, h 0, S O, P 0 is the respective value at the start rolling of the rolled material 2.

Further, the plate thickness control unit 10 has a parameter optimization unit 10E and a plate thickness compensation unit 10F.
The parameter optimum part is a value obtained by adding the plate thickness error estimated by the plate thickness error estimating part 10C to the gauge meter plate thickness obtained by the gauge meter plate thickness calculating part 10B and the outlet side of the rolling mill 1 measured by the outlet side plate thickness measuring part 5. The coefficients a, b and c which are time-varying parameters are optimized based on the difference from the measured value of the plate thickness of the material to be rolled 2 in.
In the parameter optimizing unit 10E of the present embodiment, the time-varying parameters a, b, and c are estimated by configuring a Kalman filter in which the measured value of the plate thickness of the material 2 to be rolled on the exit side of the rolling mill 1 is used as the observed amount. To optimize.
The strip thickness compensating unit 10F performs dead time compensation on the strip thickness measurement value measured by the delivery side strip thickness measuring unit 5 and converts it into strip thickness at the position of the rolling mill 1.

<Other effects>
According to the present embodiment, the coefficient of the estimated plate thickness error (time-varying parameter) is estimated from the inlet side tension, the outlet side tension, and the line speed, and the roll opening is manipulated in the direction to cancel the plate thickness error. Thus, it is possible to suppress deviation of the plate thickness tolerance when acceleration/deceleration occurs.
Further, by performing dead time compensation on the plate thickness measurement value, the plate thickness error coefficient to be estimated (time-varying parameter), that is, the plate thickness error is sequentially estimated by the Kalman filter while considering the plate conveyance delay. Further, the control accuracy is improved.
The plate thickness control of the present embodiment is performed by combining it with feedback control (monitor AGC) or the like, which uses a deviation of the actual value of the plate thickness gauge installed on the output side of the rolling mill 1 from a target value as a control input. Is also good.

A simulation study was conducted on the case where the practicality of the control method of the present invention was applied to the first stand under the following conditions.
・Inlet plate thickness setting: 0.2 mm
・Output side plate thickness setting: 0.16 mm
・Inlet unit tension setting value: 9 kgf/mm ²
・Output tension setting: 14 kgf/mm ²
・Rolling line speed: 100 m/min to 700 m/min

The examination results are shown in FIG.
As can be seen from FIG. 4, the plate thickness error of the gauge meter plate thickness that changes due to acceleration/deceleration can be successively estimated with an accuracy of ±5% or less.
Here, the estimation result shown in FIG. 4 shows the result of estimating the error of the gauge meter equation directly below the first stand by the above estimation method. In Fig. 4, the actual error is evaluated based on the thickness gauge installed on the outlet side of the first stand, and the estimated error value (directly below the rolling mill 1) can be calculated quickly by the dead time required for observation. I know that
Further, “accuracy within ±5%” means 5% or less (0.008 mm) with respect to the target plate thickness (output side plate thickness setting value: 0.16 mm).

1 Rolling Mill 1a Work Roll 2 Rolled Material 3 Entry Side Tension Measuring Section 4 Exit Side Tension Measuring Section 5 Exit Side Sheet Thickness Measuring Section 6 Rolling Down Device 7 Rolling Load Measuring Section 8 Roll Peripheral Speed Measuring Section 10 Sheet Thickness Control Section 10A Control Start Time information acquisition unit 10B Gauge meter plate thickness calculation unit 10C Plate thickness error estimation unit 10D Roll opening operation unit 10E Parameter optimization unit 10F Plate thickness compensation unit P Rolling load S Roll opening a, b, c Time-varying parameters (coefficients) )
h _GM gauge meter thickness Δd Thickness error

Claims (9)

When obtaining the gauge meter plate thickness on the rolling mill exit side from the roll opening of the rolling mill for rolling the material to be rolled and the measured value of the rolling load,
Acquired lock-on or rolling start, roll peripheral speed of the rolling rolls of the rolling mill, the tension of the rolled material at the entry side of the rolling mill, and the tension of the rolled material at the rolling mill exit side, respectively, standard It is set in advance as the roll peripheral speed, reference inlet tension, and reference outlet tension.
The estimated plate thickness error of the gauge meter plate thickness with respect to the true plate thickness, the deviation of the roll peripheral speed of the rolling roll with respect to the reference roll peripheral speed, and the material to be rolled at the rolling mill entry side with respect to the reference entry side tension. Of the deviation of the tension of the, the deviation of the tension of the material to be rolled at the rolling mill exit side to the reference exit side tension is represented by an error estimation formula that is linearly combined with a time-varying parameter,
Based on the deviation and the gauge meter thickness was compensated by the thickness error was the estimated, the thickness measurement of the material to be rolled at the delivery side of the rolling mill, you characterized by optimizing the varying parameters during the gain Jimeta plate thickness error estimation method. The gauge meter according to claim 1 , wherein the time-varying parameter is optimized by constructing and estimating a Kalman filter in which the measured value of the thickness of the material to be rolled on the outlet side of the rolling mill is an observed amount. Estimation method of plate thickness error. The method according to claim 1 or claim 2, characterized in that dead time compensation is performed on the measured value of the thickness of the material to be rolled at the rolling mill exit side, and the measured value of the thickness is converted into the thickness at the position of the rolling mill. The method for estimating a gauge meter plate thickness error described in 2 . Fixed gauge meter thickness successively by the thickness error of estimating a gauge meter thickness error estimation method according to any one of claims 1 to 3, the roll angle on the basis of the gauge meter thickness of the modified A method for controlling the plate thickness, which comprises: A method for manufacturing a material to be rolled, the thickness of which is controlled by the thickness control method according to claim 4 . An entry side tension measurement unit that measures the tension of the material to be rolled on the entry side of the rolling mill,
An outlet tension measuring unit that measures the tension of the material to be rolled on the outlet side of the rolling mill,
Roll peripheral speed measuring unit for measuring the roll peripheral speed of the rolling roll of the rolling mill,
A rolling load measuring unit for measuring the rolling load of the rolling mill,
Based on the rolling load measured by the rolling load measuring unit, a gauge meter plate thickness calculating unit for obtaining a gauge meter plate thickness,
A plate thickness error estimating unit that estimates a plate thickness error of the gauge meter plate thickness calculated by the gauge meter plate thickness calculating unit,
The gauge meter plate thickness calculated by the gauge meter plate thickness calculation unit, a roll opening operation unit that operates the roll opening of the rolling mill based on a correction value corrected by the plate thickness error estimated by the plate thickness error estimation unit, Equipped with
The plate thickness error estimation unit,
Obtained at the time of lock-on or at the start of rolling, the roll peripheral speed of the rolling roll of the rolling mill, the tension of the material to be rolled on the rolling mill entrance side, and the tension of the material to be rolled on the rolling mill exit side are each a reference. Set as roll peripheral speed, reference inlet tension, and reference outlet tension,
The thickness error, a roll peripheral speed difference of the rolling rolls with respect to the reference roll peripheral speed, the deviation of the tension of the rolled material at the entry side of the rolling mill relative to the reference entry side tension, rolling against the reference outlet side tension The deviation of the tension of the rolled material on the exit side is expressed by an error estimation formula that is linearly combined with a time-varying parameter,
A plate thickness control device, wherein a plate thickness error is estimated from each measurement value measured by the inlet side tension measuring unit, the outlet side tension measuring unit and the roll peripheral speed measuring unit and the error estimating formula. An output side plate thickness measurement unit that measures the plate thickness of the material to be rolled on the output side of the rolling mill,
A value obtained by adding the plate thickness error estimated by the plate thickness error estimation unit to the gauge meter plate thickness calculated by the gauge meter plate thickness calculation unit and the rolling material on the rolling mill output side measured by the output side plate thickness measurement unit. Based on the difference with the plate thickness measurement value, a parameter optimization unit for optimizing the time-varying parameter,
The plate thickness control device according to claim 6 , further comprising: The parameter optimization unit is characterized by optimizing the time-varying parameter by constructing and estimating a Kalman filter having a measured value of the plate thickness of the material to be rolled on the rolling mill exit side as an observed amount. Item 7. The plate thickness control device described in item 7 . Performing the dead time compensation to the thickness measurements the delivery side thickness measuring section has measured, according to claim 7 or claim 8, characterized in that it comprises a plate thickness compensating portion for converting the thickness of the rolling machine position The plate thickness control device described in 1.

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