JPH0815609B2 - Roll thickness control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip thickness control method for a rolling mill.

[0002]

2. Description of the Related Art As a method for controlling the thickness of a rolling mill of this type,
For example, the one disclosed in Japanese Examined Patent Publication No. 3-66044 is known. In this conventional one, the roll gap (reduction ratio) is controlled according to the change in the inlet side plate thickness so that the plate thickness on the outlet side of the rolling mill becomes constant.

[0003]

In the rolling of spring steel or the like, it is important to make the material hardness (hardness) uniform while the plate thickness is constant. That is, if a hard portion and a soft portion are mixed in the longitudinal direction of the rolled material, the spring will be a defective product. However, when the conventional plate thickness constant control is performed, there is a problem that the hardness of the rolled material becomes uneven in the longitudinal direction.

That is, in order to keep the plate thickness constant, the reduction ratio must be controlled, but if the reduction ratio is different, the material hardness changes, and it is impossible to roll to a uniform hardness. Therefore, conventionally, in order to eliminate the difference in hardness, heat treatment such as annealing must be performed, and an extra step for that has been required. Therefore, an object of the present invention is to provide a plate thickness control method for a rolling mill that can keep the material hardness constant.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the feature of the present invention according to claim 1 resides in that the output side plate thickness deviation target value Δhc of the rolled material is obtained from the target reduction ratio R and the input side plate thickness deviation ΔH by Δhc = (1-R) ΔH, and , An error Δhe from the outlet side plate thickness deviation Δh is obtained by Δhe = Δh−Δhc, and the roll gap control amount ΔS is calculated based on the error Δhe.

[0006]

[Expression 5] ΔS = {(M + m) / M} · {Δhe + (1 /
T2) ∫Δhe dt} However, M: Mill constant m: Deformation resistance coefficient T2: Integration time.

According to a second aspect of the present invention, the roll gap control amount ΔS is based on the error Δhe.
To

[0008]

[Equation 6] ΔS = {(M + m) / M} · (1 / T2) ∫Δ
he dt However, it is at a point determined by M: Mill constant m: Deformation resistance coefficient T2: Integration time.

According to a third aspect of the invention, the feed-forward control is performed by measuring the entrance-side thickness deviation ΔH and multiplying the measured entrance-side thickness deviation ΔH by a predetermined control gain value A. The roll gap ΔS

[0010]

[Expression 7] ΔS = A · (m / M) · ΔH, where m is the plastic constant of the rolled material, M is the mill constant, and the actual rolling reduction R _j of the rolled material is controlled by the mill constant. A deviation ΔR _j = R _j between the calculated reduction ratio R _j and the preset target reduction ratio R.
-R is calculated, and the control gain value A is changed according to A = C · (1-ΔR _j ), where C is a constant.

In the present invention as set forth in claim 3, the actual inlet side thickness deviation average value ΔH 'and the actual outlet side thickness deviation average value Δh' are obtained by measurement, and both of the sheet thickness deviation average values are obtained. From the target inlet side plate thickness H and the target outlet side plate thickness h, the actual rolling reduction R _j of the rolled material is calculated.

[0012]

R _j = {(H + ΔH ′) − (h + Δh ′)} /
It is purposeful to calculate based on (H + ΔH '). Further, the entry-side rolling speed V and the exit-side rolling speed v were measured, and the actual rolling reduction R _j of the rolled material was calculated based on R _j = 1-V / v from the measured both rolling speeds. The rolling reduction may be used.

[0013]

According to the first aspect of the invention, the monitor AGC is used to control the output side plate thickness deviation required to keep the reduction rate constant to the output side plate thickness deviation target. It becomes possible and the material hardness can be made constant. That is, the target reduction rate R is given by the following equation.

[0014]

[Equation 9] R = (H−h) / H (1) where, H: inlet side plate thickness set value h: outlet side plate thickness set value Further, the actual rolling reduction R ′ can be calculated by the following formula.

[0015]

R '= {H + ΔH- (h + Δh)} / (H +
ΔH) (2) where ΔH: deviation of thickness of inlet side Δh: deviation of thickness of outlet side Therefore, the condition for setting the actual reduction ratio R ′ to the target reduction ratio R is R = R ′. That is,

[0016]

(H−h) / H = {H + ΔH− (h + Δ
h)} / (H + ΔH) In summary, h / H = Δh / ΔH (3) Substituting equation (3) into equation (1) and solving for Δh, Δh = (1-R) · ΔH (4), which becomes the control principle formula.

In the equation (4), the target rolling reduction R is known, and the inlet side plate thickness deviation value ΔH can be measured by the inlet side thickness gauge. Therefore, if the output side plate thickness deviation Δh is controlled so as to satisfy the above equation (4), it is possible to control the actual reduction rate to the target reduction rate. Therefore, a system is constructed so that the deviation Δh of the outgoing side plate thickness satisfies the above expression (4).

Δh calculated by the equation (4) is a target value. Δh in equation (4) is set as Δhc, and this is set as the output side plate thickness deviation target value. That is,

[0019]

[Formula 12] Δh c = (1−R) · ΔH (5) The actual outlet side plate thickness deviation Δh is measured by the outlet side plate thickness gauge. If the error between the actual value Δh and the target value Δhc is Δhe, Δhe is given by the following equation.

.DELTA.he = .DELTA.h-.DELTA.hc (6) In the above equation (6), control may be performed so that .DELTA.he = 0. Then, substituting equation (5) into equation (6),

[0021]

[Formula 13] Δhe = Δh-Δhc = Δh- (1-R) · ΔH (7) However, in the equation (7), the inlet plate thickness deviation ΔH is a value at the same point as the outlet plate thickness deviation Δh.

This system can be realized by applying the equation (7) to the control equation of the monitor AGC to control the roll gap. The control equation of the monitor AGC is given by the following equation.

[0023]

[Expression 14] ΔS = {(M + m) / M} · {Δh + (1 /
T2) ∫Δhdt} (8) where ΔS: roll gap control amount M: mill constant m: deformation resistance coefficient Δh: delivery side plate thickness deviation T2: integration time The target value of the equation (8) is Δh = 0. Therefore, Δ in Eq. (8)
Δhe in equation (7) can be substituted for h. That is,

[0024]

[Expression 15] ΔS = {(M + m) / M} · {Δhe + (1
/ T2) ∫ Δhe dt} (9) By controlling the roll gap based on the control equation, it is possible to control the rolling reduction constant. It is to be noted that the invention according to claim 2 uses the following equation in place of the equation (9).

[0025]

[Expression 16] ΔS = {(M + m) / M} · (1 / T2) ∫
Δhe dt (9) 'The invention according to claims 1 and 2 relates to constant rolling reduction control in the monitor AGC control.
The described invention relates to constant reduction control in feed forward control.

That is, the invention according to claim 3 is a feed
Forward AGC control type

[0027]

[Expression 17] ΔS = A · (m / M) · ΔH where ΔS: roll gap control amount m: plastic constant of rolled material M: mill constant A: control gain value ΔH: control gain value A at inlet side plate thickness deviation To

[0028]

A = C · (1−ΔR _j ) where C: constant ΔR _j = R _j −R R _j : actual reduction ratio R: reduction ratio deviation (1−ΔR _j ) such as target reduction ratio Since it is changed in proportion, it is possible to perform control with a constant reduction rate. Since the rolling reduction is constant, the hardness of the rolled material is constant.

The reason why the rolling reduction becomes constant is as follows. When the actual reduction rate R _j matches the target reduction rate R (R _j = R), ΔR _j = R _j −R = 0, so A = C · (1−ΔR _j ) = C. And A =
It is controlled by the control gain value of C. The actual rolling reduction R _j is larger than the target rolling reduction R (R _j
> R) is when the plate is crushed too much, so the control gain value A needs to be smaller than A = C. Therefore, in A = C · (1−ΔR _j ), ΔR _j > 0, so C · (1−ΔR _j ) <C, and if an appropriate C is given, the control gain value A becomes A <C. Become. This eliminates over-squashing and gives R _j = R. The actual rolling reduction R _j is smaller than the target rolling reduction R (R _j
In the case of <R), it is necessary to further crush the plate, so the control gain value A needs to be larger than A = C. Therefore, in A = C · (1-ΔR _j ), ΔR _j
Since <0, C · (1−ΔR _j )> C, and by giving an appropriate C, A> C. This allows for more crushing and gives R _j = R.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of a plate thickness control device for a rolling mill used in the method of the present invention to which the monitor AGC control system is applied, in which a rolled material 21 is fed from an inlet side reel 22 and an outlet side reel 23. It is rolled by a rolling mill 24 while being wound into the.

On the entrance side of the rolling mill 24, there is provided an entrance side plate thickness gauge 25 for measuring the plate thickness H _i of the entrance side rolled material 21 and outputting it as the entrance side plate thickness deviation ΔH. Here, the entrance side plate thickness deviation ΔH
Means the difference between the set entrance side plate thickness H and the actual entrance side plate thickness H _i . (Hereinafter, the terms “setting” and “target” are used as synonyms.) At the exit side of the rolling mill 24, the strip thickness h _i of the strip 21 on the exit side is measured, and the strip thickness deviation Δh An output side plate thickness gauge 26 for outputting as is provided. Here, the outlet side plate thickness deviation Δh means a difference between the target outlet side plate thickness h and the actual outlet side plate thickness h _i . The subscript i
Means the number of samplings.

Further, on the entrance side of the rolling mill 24, there is provided an entrance speed detector 27 for detecting the entrance speed of the rolled material 21.
The speed detector 27 is composed of a pulse generator. The rolling mill 24 is provided with a rolling down device 28 for adjusting the gap between a pair of upper and lower work rolls. Further, a control device 29 for controlling the reduction device 28 is provided.

The control device 29 inputs the signals from the entrance side plate thickness gauge 25 and the speed detector 27 to track the entrance side plate thickness deviation, and a numerical setting device 31 for setting various target values. And a control calculator 32 for performing various calculations based on signals and data from the tracking circuit 30, the numerical setting device 31, and the output side plate thickness gauge 26, and a PI (differential integration) controller
33, and is configured to output a predetermined control amount to the reduction device 29.

The control unit 29 is composed of a control electronic computer composed of hardware such as a CPU and a memory, and software consisting of a program for controlling the hardware. The control for making the rolling reduction of the rolled material 21 constant by using the apparatus having the above-described configuration will be described below.

When the control is started, in the first step, the control calculator 32 reads the input side plate thickness set value H and the output side plate thickness set value h from the numerical value setter 31. In the second step,
The control calculator 32 calculates the target reduction rate R based on the following equation.

[0036]

[Formula 19] R = (H−h) / H (1) where H: Incoming plate thickness setting value h: Outgoing plate thickness setting value In the third step, the deviation of the incoming plate thickness ΔH in the tracking circuit 30 is calculated. Tracking is done.

In the fourth step, the outlet side plate thickness deviation Δh is read into the control calculator 32. In the fifth step, the read-out output thickness deviation Δh and the input-side thickness deviation ΔH at the same point are read into the control calculator 32. Then, in the sixth step, the calculation of the output side target thickness deviation value Δhc is performed by the control calculator 32 based on the following equation.

[0038]

[Formula 20] Δhc = (1−R) · ΔH (5) In the seventh step, the error Δhe between the actual output side plate thickness deviation value Δh and the target deviation value Δhc is calculated by the control calculator 32 as follows. It is calculated by the formula. Δhe = Δh−Δhc (6) In the eighth step, the PI controller 33 calculates the roll gap control amount ΔS based on the following equation.

[0039]

[Expression 21] ΔS = {(M + m) / M} · {Δhe + (1
/ T2) ∫Δhe dt} (9) where M: Mill constant m: Deformation resistance coefficient T2: Integral time and in the ninth step, the roll gap control amount ΔS is output to the rolling down device 28 to generate the roll gap. Is controlled.

According to the above-mentioned embodiment, as explained in the section of the above-mentioned operation, the control is such that the equations (1) and (2) are equal, so that the actual reduction rate R'is equal to the target reduction rate R. It becomes equal and the rolling reduction becomes constant. The same effect can be obtained by using the following formula instead of the formula (9).

[0041]

[Expression 22] ΔS = {(M + m) / M} · (1 / T2) ∫
Δhe dt (9) 'FIG. 4 is a block diagram of a plate thickness control device of a rolling mill used in the method of the present invention which employs feed forward AGC control. While being unrolled from the reel 2 and wound on the reel 3 on the delivery side, the rolling mill 4 rolls the rolled reel.

On the entrance side of the rolling mill 4, there is provided an entrance side plate thickness gauge 5 for measuring the plate thickness H _i of the entrance side rolled material 1 and outputting it as an entrance side plate thickness deviation ΔH. Here, the entrance side plate thickness deviation ΔH
Means the difference between the set entrance side plate thickness H and the actual entrance side plate thickness H _i . On the output side of the rolling mill 4, the strip thickness gauge 6 for measuring the strip thickness h _i of the strip 1 on the strip side and outputting it as the strip thickness deviation Δh 6
Is provided. Here, the outlet side plate thickness deviation Δh means a difference between the target outlet side plate thickness h and the actual outlet side plate thickness h _i . The subscript i means the sampling number.

Further, on the entrance side of the rolling mill 4, there is provided an entrance speed detector 7 for detecting the entrance speed of the rolled material 1.
This speed detector 7 is composed of a pulse generator. The input side speed detector 7 is connected to an output timing circuit 8 which delays a signal by a considerable time in consideration of the running time of the rolled material 1 from the input thickness gauge 5 of the rolled material 1 to the rolling mill 4. The output timing circuit 8 is connected to a reduction control device 9 that changes the roll gap ΔS of the rolling mill 4 to control the outlet plate thickness of the rolled material 1. The outlet plate thickness gauge
Reference numeral 6 is connected to a feedback control device 10 which feedback-controls the integrated amount of the outlet side plate thickness deviation to the reduction control device 9.

The output timing circuit 8 is a control arithmetic unit.
Connected to 11. The control computer 11 is a control electronic computer including hardware such as a CPU and a memory, and software including a program for controlling the hardware, and includes a numerical value setting means 12 and a first arithmetic means.
It has 13, a second computing means 14, a memory 15, and an AGC control means 16. AGC is an abbreviation for Automatic Gauge Control.

The numerical value setting means 12 presets the plastic constant m of the rolled material 1 and the mill constant M of the rolling mill 4. The first calculation means 13 is connected to the numerical value setting means 12 and the entrance side plate thickness gauge 5, receives the entrance side plate thickness deviation ΔH, and multiplies it by (m / M). The second computing means
Reference numeral 14 is connected to the first calculating means 13 and the memory 15, calculates the roll gap ΔS of the rolling mill 4 based on ΔS = A · (m / M) · ΔH, and outputs it to the output timing circuit 8. It is a thing. Here, A is a control gain value, which is stored in the memory 15.

The AGC control means 16 is the entrance side plate thickness gauge.
5 and the output side thickness gauge 6, the control gain value A is calculated from the measurement value of the input side thickness gauge 5 and the measurement value of the output side thickness gauge 6 and is output to the memory 15. Below, the A
The calculation procedure by the GC control means 16 will be described with reference to FIGS. First, in step 1, the dead zone value E, the target entrance side plate thickness H, and the target exit side plate thickness h are set.

In step 2, a preset rolling reduction (hereinafter referred to as "rolling reduction set value") R is calculated by the following equation. R = (H−h) / H In step 3, the entrance side thickness deviation average value ΔH ′ is calculated. This step 3 is processed by the subroutine shown in FIG.

That is, the inlet side plate thickness deviation value ΔH _i is obtained by ΔH _i = H _i −H, and the inlet side plate thickness deviation average value ΔH ′ is

[0049]

(23) ΔH ′ = (ΔH ₁ + ΔH ₂ + ... + ΔH _n ) / n Note that n is the number of samplings, and this sampling is performed in a predetermined cycle. That is, the entry side thickness gauge
By reading the signal No. 5 at a predetermined sampling pitch, the actual entrance side plate thickness H _i is read, the entrance side plate thickness deviation value ΔH _i is obtained, and the entrance side plate thickness deviation average value ΔH ′ is obtained.
Is required.

At step 4, the average value Δ of the deviation of the plate thickness on the outgoing side is obtained.
Calculate h '. This step 4 is processed by the subroutine shown in FIG. First, the entrance side plate thickness deviation ΔH _i
Is tracked by the signal of the inlet speed detector 7 to find the point where the same point on the rolled material 1 reaches the outlet plate thickness gauge 6. Then, the entrance side plate thickness deviation ΔH _i and the exit side plate thickness deviation Δh _i at the same point are read. Then, the outlet plate thickness deviation Δh _i
The average value Δh ′ of is calculated.

The output side thickness deviation Δh _i and its average value Δh ′ are determined by the above-mentioned input side thickness deviation ΔH _i ,
Also, since it is the same as the method of obtaining the average value ΔH ′ of the entrance side plate thickness deviation, the description thereof will be omitted. In step 5, the actual rolling reduction R _j is calculated. This reduction ratio R _j is

[0052]

R _j = {(H + ΔH ′) − (h + Δh ′)}
It is calculated based on / (H + ΔH '). The subscript j is a control cycle of the rolling reduction calculation device, and the control cycle j and the plate thickness measurement sampling cycle i are different from each other. In step 6,
The rolling reduction error ΔR _j is calculated. The rolling reduction error ΔR _j is the difference between the actual rolling reduction R _j and the preset rolling reduction R and is given by the following equation.

ΔR _j = R _j -R In step 7, it is judged whether or not the error ΔR _{j in the} reduction rate is within the dead zone E. When ΔR _j <E, a sufficient reduction rate is obtained, so the control gain value A is not changed and the process skips to step 9 described later.

When ΔR _j ≧ E, a sufficient reduction ratio is not obtained, so the control gain value A is changed and the process proceeds to the next step 8 in order to bring the reduction ratio closer to the set value R. In step 8, the control gain value A is changed by the following equation. A = C · (1−ΔR _j ) where C is a fixed gain.

The changed control gain value A is stored in the memory 15
It is replaced with the control gain value A stored in. This new control gain value A is called by the second calculating means 14. In step 9, whether or not to continue the calculation is determined by referring to the switch on the operation panel. To continue, return to step 3 above. When not continuing, go to the end and end.

Next, the operation of the above embodiment will be described.
First, in order to facilitate understanding of the operation of the embodiment of the present invention, a conventional plate thickness control (described in Japanese Patent Publication No. 3-66044) will be described with reference to FIGS. 9 and 10. FIG. 9 shows the behavior of the entrance side plate thickness deviation, and FIG. 10 shows the behavior with respect to the entrance side plate thickness of FIG.
The behavior of the outlet side plate thickness deviation when the conventional feedforward AGC is executed is shown. Points A and B in FIG. 9 correspond to points A ′ and B ′ in FIG. 10.

In the conventional plate thickness control, the plate thickness on the delivery side is controlled to a constant value. Therefore, when feedforward AGC is executed, the deviation in the plate thickness on the delivery side becomes zero. In this case, the target reduction ratio R is

[0058]

[Formula 25] R = (H-h) / H = (0.2-0.1) /0.2=
If it is 0.5, the actual reduction ratio R _A '(the reduction ratio at point A) is

[0059]

R _A '= {(H + ΔH)-(h + Δh)} /
(H + ΔH) = {(0.2 + 0.01)-(0.1 + 0.0)} / (0.2 + 0.01) = 0.502, which causes a deviation of 0.002 from the target rolling reduction R = 0.5. Similarly, the rolling reduction R _B 'at the point _B is

[0060]

R _B '= {(H + ΔH)-(h + Δh)} /
(H + ΔH) = {(0.2-0.005)-(0.1 + 0.0)} / (0.2-0.005) = 0.487, which deviates from the target reduction rate. That is, in the conventional method, the deviation of the plate thickness on the delivery side can be controlled to zero, but the reduction ratio cannot be controlled to the target value, resulting in a difference in hardness.

In contrast to the conventional plate thickness constant control described above, in this embodiment, the roll gap ΔS control formula is the same as the conventional one.

[0062]

[Expression 28] ΔS = A · (m / M) · ΔH where m: plastic constant of rolled material M: mill constant is used, but the control gain value A is A = C · (1-ΔR _j ) C: It changes based on a constant. If this control is performed, the deviation of the plate thickness on the delivery side becomes as shown in FIG.

That is, the delivery side plate thickness is not constant as in the conventional case, and the plate thickness accuracy is slightly deteriorated, but the reduction ratio matches the target value and the hardness is constant. That is, the entrance side plate thickness is as shown in FIG.
In the present embodiment, the rolling reduction error ΔR _{j at the} point A ′ is as shown in FIG.

[0064]

[Number 29] Since the _{ΔR j = R A '-R =} 0.502 -0.5 = 0.002,

[0065]

Equation 30] A = C · (1-ΔR j) = 0.998 C next, by using the control gain value A, by controlling the roll gap [Delta] S, the state shown in FIG. 11. That is,
The deviation Δh of the outgoing side plate thickness at the point A ”is +0.005.

The actual rolling reduction R _A "at point _A " is

[0067]

R _A "= {(H + ΔH)-(h + Δh)} /
(H + ΔH) = {(0.2 + 0.01)-(0.1 + 0.005)} / (0.2 + 0.01) = 0.5, and _RA "= R, the reduction ratio becomes the target value, and the hardness becomes uniform. What is shown is a block diagram of a plate thickness control device used in another embodiment of the present invention.

In the apparatus shown in FIG. 12, an exit speed detector 17 for detecting the speed of the exit rolled material 1 is provided on the exit side of the rolling mill 4, and the exit speed detector 17 is the AGC. Control means
It differs from that shown in FIG. 4 in that it is connected to 16.
The AGC control means 16 is different from the above embodiment in that the following processing is performed.

That is, in this embodiment, the actual reduction ratio R _j
Is calculated based on R _j = 1−V / v. Here, V is the incoming speed detector 7
Is the incoming rolling speed, and v is the outgoing rolling speed detected by the outgoing speed detector 17. Next, the relational expression is derived.

The rolling reduction is

[0071]

R _j = {(H + ΔH) − (h + Δh)} / (H + ΔH), which is defined as

[0072]

[Expression 33] R _j = {(H + ΔH)-(h + Δh)} / (H + ΔH) = 1- (h + Δh) / (H + ΔH). Here, the volume of the incoming side rolled material and the outgoing side rolled material, from the same conditions,

[0073]

(H + ΔH) · V = (h + Δh) · v ∴ (h + Δh) / (H + ΔH) = V / v Therefore,

[0074]

R _j = {(H + ΔH)-(h + Δh)} /
(H + ΔH) = 1- (h + Δh) / (H + ΔH) = 1-V / v.

Therefore, in this embodiment, the AGC control means 16 processes according to the procedure shown in FIG. In place of steps 3 to 5 of the above-mentioned embodiment, this embodiment is different from the above embodiment in that the inlet and outlet velocities V and v are read and the values are used to calculate the actual rolling reduction R _j. The other steps are the same.

In the above embodiment, the calculation of the actual rolling reduction is
Since it is obtained from the signals of the inlet and outlet plate thickness gauges 5, 6,
Especially on the exit side, there is a problem that it takes time for the rolled material 1 immediately below the rolling mill 4 to reach the exit side plate thickness gauge 6, and the detection is delayed. However, in this embodiment, since the speed on the input side and the speed on the output side are used, detection delay does not occur, and accurate control can be performed.

The present invention is not limited to the above embodiments.

[0078]

According to the present invention, since the rolling reduction can be brought close to the target value, the rolling reduction can be controlled to be constant, so that the hardness of the rolled material can be made uniform.

[Brief description of drawings]

FIG. 1 is a first half of a flow chart showing a processing procedure of the present invention.

FIG. 2 is the latter half of the flow chart.

FIG. 3 is a block diagram of an apparatus using the method of the present invention.

FIG. 4 is a configuration diagram of a plate thickness control device used in another embodiment of the present invention.

FIG. 5 is a first part of a flowchart showing a processing procedure of another embodiment of the present invention.

FIG. 6 is a second part of a flowchart showing a continuation of the flowchart.

FIG. 7 is a flow chart showing a subroutine for obtaining an average value of deviations of sheet thickness on the entrance side.

FIG. 8 is a flowchart showing a subroutine for obtaining an average value of the outlet side plate thickness deviation.

FIG. 9 is a graph showing an entrance-side plate thickness deviation.

FIG. 10 is a graph showing the deviation of the outlet plate thickness when the conventional method is performed.

FIG. 11 is a graph showing the deviation of the outlet plate thickness according to the method of the present invention.

FIG. 12 is a configuration diagram of a plate thickness control device used in another embodiment of the present invention.

FIG. 13 is a flowchart showing a processing procedure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 4 Rolling mill 5 Input side thickness gauge 6 Output side thickness gauge 7 Input side speed detector 11 Control calculator 16 AGC control means 17 Output side speed detector 21 Rolled material 24 Rolling machine 25 Input side thickness gauge 26 Output side plate Thickness gauge 28 Roll-down device 29 Control device

Claims (5)

[Claims] 1. The target value Δhc of the strip thickness deviation of the rolled material is calculated from the target reduction ratio R and the strip thickness deviation ΔH of the entry side by Δhc = (1−R) ΔH, and the error Δhe from the strip thickness deviation Δh of the exit side is calculated. , Δhe = Δh−Δhc, and based on the error Δhe, the roll gap control amount ΔS is given by: ΔS = {(M + m) / M} · {Δhe + (1 /
T2) ∫Δhe dt} where M: Mill constant m: Deformation resistance coefficient T2: Integral time. 2. A target value Δhc of the strip thickness deviation of the rolled material is obtained from the target reduction ratio R and the strip thickness deviation ΔH of the entry side by Δhc = (1−R) ΔH, and further, an error Δhe with the strip thickness deviation Δh of the exit side is obtained. , Δhe = Δh−Δhc, and based on the error Δhe, the roll gap control amount ΔS is given by: ΔS = {(M + m) / M} · (1 / T2) ∫Δhe dt where M: mill constant m : Deformation resistance coefficient T2: Sheet thickness control method for rolling mills, which is obtained by integration time. 3. A roll gap ΔS is calculated by feedforward control using a value obtained by measuring an inlet side thickness deviation ΔH and multiplying the measured inlet side thickness deviation ΔH by a predetermined control gain value A. A · (m / M) · ΔH However, in the strip thickness control method of the rolling mill controlled by m: plastic constant of rolled material, M: mill constant, the actual rolling reduction R _j of the rolled material is calculated and obtained. Deviation ΔR _j between the calculated rolling reduction R _j and the preset target rolling reduction R
= R _j −R is calculated, and the control gain value A is changed based on A = C · (1−ΔR _j ) where C: a constant. 4. An actual inlet side thickness deviation average value ΔH ′ and an actual outlet side thickness deviation average value Δh ′ are measured and obtained, and both of these sheet thickness deviation average values, the target inlet side thickness H and the target output thickness are calculated. From the side plate thickness h, the actual rolling reduction R _j of the rolled material can be calculated as follows: R _j = {(H + ΔH ′) − (h + Δh ′)} /
The strip thickness control method for a rolling mill according to claim 2, wherein the strip thickness is calculated based on (H + ΔH '). 5. An incoming rolling speed V and an outgoing rolling speed v are measured, and the actual rolling reduction R _j of the rolled material is calculated from the measured rolling speeds based on R _j = 1-V / v. The sheet thickness control method for a rolling mill according to claim 2, wherein