JPS62289312A - Control device for rolling mill - Google Patents

Abstract

PURPOSE:To detect the eccentric amount of a roll with high accuracy and to improve the plate thickness accuracy by performing a Fourier analysis based on the plate thickness deviation signal of a rolling stock. CONSTITUTION:The output of an adder 22 is subjected to a sampling with the output timing of mark pulse oscillators 4A, 4B and sampling pulse oscillators 5A, 5B by an arithmetic storing means 17, arithmetic means 18, Fourier convertor 19 and arithmetic means 20, subjected to a Fourier convertion, outputting roll eccentric piece amplitudes XA, XB and phase angles phiA, phiB. A roll eccentricity reproducing means 12 reproduces a roll eccentric amount SE taking into consideration the phase as well based on the current azimuthes thetaA, thetaB of the backup rolls 2A, 2B of the output of a turning angle arithmetic means and the roll eccentric piece amplitudes XA, XB and phase angles phiA, phiB.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for eliminating the influence of roll eccentricity of a rolling mill for rolling steel plates and the like.

(Prior art) In a rolling mill that rolls steel plates, etc., plate thickness fluctuations or tension fluctuations due to fluctuations in the O-ru gap due to eccentricity of the backup roll can improve product quality and ensure stable rolling operations. There is a big disturbance at the top.

Particularly in recent years, rolling mills equipped with hydraulic rolling devices with fast response speed have come into use, and in order to take advantage of this high-speed response characteristic and produce products with excellent plate thickness accuracy, roll eccentricity must be eliminated. Must.

As a typical example of a method for detecting roll eccentricity, JP-A-60-14
There is a method disclosed in Japanese Patent No. 1321. this is,
This is a method in which the rolling load signal is subjected to Fourier analysis to individually detect the eccentricity m of the upper and lower backup rolls.

FIG. 4 is a block diagram of a conventional control device that eliminates the influence of roll eccentricity based on a rolling load signal. IA, 1
B are upper and lower work rolls, 2A and 2B are upper and lower backup rolls, 3 is a rolling load detector, 4A,
4B is a mark pulse transmitter that generates one pulse with each rotation of the upper and lower backup rolls, 5A and 5B are sampling pulse generators that each generate N pulses with one rotation of the upper and lower backup rolls, and 6 is a signal between the upper and lower work rolls. Hydraulic reduction control device to control the roll gap of
Reference numeral 7 denotes a roll eccentricity detection means, and reference numeral 8 indicates a roll gap variation due to roll eccentricity based on the half amplitudes xA, XB and phase angles φA, φB of the eccentricity of the upper and lower backup rolls detected by the roll eccentricity detection means 7. Roll eccentricity regeneration 1 (11111 means) calculates the roll gap control length ΔSo in the canceling direction and outputs it to the hydraulic compression lower side m+ device 6.

Generally, roll eccentricity includes harmonic components, but in the following explanation, only the fundamental wave component of one cycle of one rotation of the backup roll will be considered.

Roll eccentricity ΔsA of the upper and lower backup rolls.

ΔSB is expressed by equations (1) and (2), respectively.

ΔS, =XA -5in (θ + φ8) ・
(1) ΔSB=×8・sin (θB+φ3) −
(2) Here XA: Upper backup roll 2A+7)
Eccentric piece amplitude XB: Eccentric piece amplitude θA of the lower backup roll 2B: Rotation angle θB of the upper backup roll 2A: Rotation angle φA of the lower backup roll 2B Phase angle of the second upper backup roll 2A with respect to the mark pulse generation position φB: Lower backup The variation in the phase angle roll gap with respect to the mark pulse generation position of the roll 2B appears as a combination of the eccentricities of the upper and lower backup rolls 2A and 2B.

ΔS[=ΔSA+ΔSB ・-・・・・(3) Also, if the variation speed of rolling load due to roll eccentricity is ΔP, then in the so-called kiss roll state where the upper and lower work rolls are tightened without rolling, ΔP= -M・ΔSE
Town...(4). In addition, when the material is being rolled, it is expressed as .

Here, M: Mill constant m: Plasticity coefficient of material The roll eccentricity detection means 7 shown in FIG. 5B
The rolling load signal is sent to the rolling load detector 3 in correspondence with the rotation angle of the upper and lower backup rolls calculated from the pulse signal of
By detecting this and performing Fourier analysis, (1)
Equation (2) Eccentric single width XA, XB and phase angle φA of the roll.

Detect φB.

The roll eccentricity regeneration control means 8 includes a mark pulse transmitter 4A.
, 4B and the pulse signals from the sampling pulse sources 5A, 5B are input, and the upper and lower backup rolls 2A,
Calculate the rotation angles θ, θ and B phase angle of 2B, reproduce the eccentricity of the upper and lower backup rolls using equations (1) and (2), and calculate the gear shift based on the combined roll eccentricity using equation (3). ! ! It_ffi is set, and a roll gap l1llllffiΔSo in which the roll gap operates in a direction to cancel this is calculated and outputted to the hydraulic pressure reduction control device 6. Therefore, the eccentric single imaging width XA of the roll is ×8 and the phase angle φ5. If φB is detected correctly,
It is possible to eliminate roll eccentricity and improve plate thickness accuracy.

Conventionally, the rolling load signal detected by the rolling load detector 3 has been used to detect O-ru eccentricity. Therefore, roll eccentricity detection accuracy largely depends on rolling load detection accuracy.

The detection accuracy of currently used rolling load detectors is limited to ±0.5% with respect to the rated load of the rolling load detector.

For example, if rolling load detectors are installed on the drive side and work side of a rolling mill, and the sum of those detected values is used as the rolling load detection value, the rated load of the rolling load detector used is 1000.
In other words, the detection accuracy is ±10 tons.

On the other hand, in cold rolling mills for thin plates, etc., the required plate thickness accuracy is extremely strict, being several μm or less.

For example, when attempting to roll to a plate thickness variation of ±1 μm, the roll gap variation ΔS is the mill constant M = 500 tons/
If the plasticity coefficient m of the material is 500 tons/m, then 500+500 = xo, ooi
=0.002, which means that only a variation of ±2 μm is allowed.

The amount of variation ΔP in rolling load due to this ±2 μm roll gap variation is 500+500 =0.5, that is, ±0.5 ton from equation (5).

This value is much smaller than the detection accuracy of the rolling load detector mentioned above, and there is a limit to the detection accuracy of the existing method of detecting roll eccentricity using the rolling load detector. There is a limit.

(Problems to be Solved by the Invention) The present invention can improve plate thickness accuracy by detecting roll eccentricity with high accuracy based on the plate Jl eccentricity signal of the rolled material and removing its influence. The purpose is to provide a control device for a rolling mill.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a rolling mill equipped with a pair of upper and lower work rolls, a pair of upper and lower backup rolls, and a hydraulic rolling control device. Mark pulse oscillator that outputs one pulse per rotation and Nil per rotation! a sampling pulse oscillator that outputs a pulse of 1; A plate thickness deviation detection means detects the plate thickness of the rolled material on the output side of the rolling mill, and outputs the deviation of the detected plate thickness from the set value of the thickness of the rolled material, and the plate thickness deviation detection means detects the thickness of the rolled material. roll gap change amount calculation means for converting the detected deviation into a roll gap change amount of the rolling mill;
a speed detector for detecting the moving speed of the rolled material, a delay means, an addition means for calculating the sum of the output of the delay means and the output of the roll gap change amount calculation means, the mark pulse generator and the sampling pulse. Fourier transform calculating means for calculating the eccentric amplitude and phase angle of the roll by sampling the output of the adding means at the output timing of the transmitter and performing Fourier transform; and the output of the Fourier transform calculating means and the rotation angle calculating means. A roll eccentricity regeneration means for regenerating the amount of roll eccentricity based on the output of the roll eccentricity regeneration means, and a roll gap control [
1, and outputs a control signal to the hydraulic pressure reduction control device so as to cancel the amount of change in the roll gap due to roll eccentricity of the rolling mill, and the delay means includes: Based on the output of the speed detector, the moving time of the rolled material between the roll of the rolling mill and the plate thickness deviation detecting means is calculated, and the output of the roll eccentricity regenerating means is delayed by the moving time. It is characterized in that it is output to an adding means.

(Principle and operation of R-light) The plate thickness deviation amount Δh of the rolled material due to the roll gap change ΔSE due to roll eccentricity is expressed by equation (6).

In the present invention, a plate thickness deviation detector is installed on the rolling exit side to detect the plate thickness deviation, and the roll eccentricity ΔS is determined from the relationship of equation (6).

Currently commonly used plate thickness deviation detectors, such as XI
The detection accuracy of the two thickness gauges is ±1.0 μm or more. Therefore, the problem with the conventional method, which is the limit in roll eccentricity detection accuracy due to the detection accuracy of the rolling load detector, is solved.

FIG. 3 is a diagram showing the arrangement relationship between the rolling mill and the plate thickness deviation detector. A rolling material 10 is rolled by a rolling mill consisting of a pair of work rolls 1A, 1B and backup rolls 2A, 2B. A plate thickness deviation detector 9 for detecting plate thickness deviation of the rolled material 10 is installed on the exit side of the rolling mill. Further, 4A and 4B are mark pulse generators that generate one pulse per rotation of the upper and lower backup rolls 2A and 2B, respectively. 5A and 5B are backup rolls 2A.

This is a sampling pulse oscillator that generates N sampling pulses per 2B rotation.

Now, if the upper and lower backup rolls 2A and 2B have roll eccentricity shown by equations (1) and (2),
The resulting variation in plate thickness appears in the plate directly below the roll.

Therefore, when detecting plate thickness variation due to roll eccentricity using the plate thickness deviation detector 9, there is a delay corresponding to the time required for the rolled material 10 to move from the rolling mill to the plate thickness deviation detector 9.

Here, the distance between the rolling mill and the plate thickness deviation detector 9 is determined, and the 0 diameter of the upper and lower backup rolls 2A and 2B is DA.

If D8, the phase delay due to the detection delay γA, γ
B is represented by .

Therefore, the amount of roll eccentricity with respect to the plate thickness deviation detected by the plate thickness deviation detector 9 is expressed by equations (9) and (10).

ΔS =XA-sin (OA+φA7A)...
...(9) ΔS =XB -5in (θB+φ37B)...
(10) FIG. 2 is a diagram showing the relationship between the upper and lower backup roll eccentricity waveforms and mark pulses. (A) is the upper backup roll mark pulse, (B) is the upper backup roll eccentric waveform, (C) is the lower backup roll mark pulse,
(D) is a lower back-up propagation eccentric waveform.

Now consider the timing at which the upper backup roll mark pulse m1 occurs. At this time, the state of roll eccentricity when the rolled material directly below the plate thickness deviation detector 9 is directly below the rolling mill is defined as timing U. The phase lag of U with respect to ml on the upper backup roll rotation angle is γ4, and the phase lag on the lower backup roll rotation angle is γ8.

Similarly, if the roll eccentricity corresponding to the rolled material 10 immediately below the plate thickness deviation detector 9 at the timing when the lower back up roll mark pulse n3 is generated is .largecircle., then the phase delays during this period are also .gamma. and .gamma.8.

In Fig. 2, φABI is the phase angle between the upper backup roll mark pulse m1 and the lower backup 0-roll eccentricity ΔS, and φ = φ + θ (11)
It is expressed as ABI B It . Here, .theta.1 is the phase angle between ml and the lower back-up roll mark pulse (nl in FIG. 2) generated before ml at the timing closest to ml. At the same time, φ is the phase angle between the lower back A3 up roll mark pulse n3 and the upper back up roll eccentricity mΔSA, φ8A3=φ, +θ
. 3 It is expressed as (12).

Here, θn3 is n3 and n3 at the timing closest to n3.
This is the phase angle between the upper backup roll mark pulse (m3 in FIG. 2) which occurred earlier than the upper backup roll mark pulse (m3 in FIG. 2). θ, θ.

is a known value that can be calculated by measuring the rotational speed of the upper and lower back signal up rolls and the time between mark pulses.

Next, the roll eccentricity m detected by the plate thickness deviation detector 9 when the arbitrary upper backup roll mark pulse mi generation timing is used as a reference (θ, = O2θ8 = 0) is ΔS1
1, Δ5H=X71-5in (θA+φA-7A)+X
-3in(θB+φABi ”B)・・・・・・(1
3) ΔS1 is the roll spacing based on the mj occurrence timing.
j, then ΔS =X −5in(θA+φA 7A)+j
A X −3in(θ +φ −γ )B
a ABjB・・・・・・(14
).

Similarly, any lower backup roll mark pulse nk
The amount of roll eccentricity based on the occurrence timing is ΔS
2, ΔS 2 = X p, Sin (θ^+φBAk
7A)+XBS! n(θ8+φ, -78) ・
(15) If the roll eccentricity based on the timing of II occurrence is ΔS, then N Δ821− XM Sln (θA+φ −7A)+
AJI XBsin(θB+φBTB)−(16).

Here, φAB is the phase angle of the lower backup roll eccentricity with respect to the upper backup roll mark pulse, φBA is the phase angle of the upper backup roll eccentricity with respect to the lower backup roll mark pulse, and φ ・=φ8+θ□i・・・・・・・・・(1
7) AB+φ,=φ+θ, ・・・・・・・・・(1
8) ABJ B IIIJ φ =φ +θ. k ・・・・・・・・・(1
9) BAk A φBAN ””φA+θ. G・・・・・・・・・
・Represented by (20).

Here θmj”θl1li+α ・・・・・・・・・
(21) θ. g=θ. k+β・・・・・・・・・
...(22), substitute equations (17), (18), and (21) into equation (14), and substitute equations (19), (20), and (22) into equation (16), and obtain (Δ511 −ΔS,j) and (
When Δ521) is calculated for ΔS2, equations (23) and (24) are obtained.

α = 2XBsin (--)cos (θB+φB+
α ・・・・・・・・・(23) θ, i-γs-T β = 2X A sin <--E) cos <
θ = φ = β. 8-γ. +5) ・・・・・・・・・(24) This δ1. When δ2 is Fourier transformed, 61 =
X 1 stn (θB+01) −・・−(2
5) δ = X2 sin (θ, +02> ・−・・−(
26) Eccentric piece amplitude x 1. x2 and phase angle θ1. θ2 is obtained.

Therefore, from equations (23) and (25), α π φ = θ −θ1+γ1■+7 ・・・・・・(28)
is obtained, and from equations (24) and (26), β π φ =θ −θ. k”A 2+wo ・・・・・・(3
0) is obtained.

As described above, by detecting the plate thickness deviation on the exit side of the rolling machine with the plate thickness deviation detector, converting this into a roll gap change amount, and further performing Fourier analysis, the upper and lower backup rolls 2A,
It has been described that the magnitude and phase of the O-le eccentricity of 2B can be detected. However, the above is a case where the roll gap is not operated by roll eccentricity removal control.

Next, a case where roll eccentricity removal control is performed will be described. If the roll gap operation amount due to roll eccentricity removal control is ΔSE, the gap change amount ε due to roll eccentricity is ε−ΔSE−ΔSE (3
1). Therefore, the amount of plate thickness change due to roll eccentricity detected by the plate thickness deviation detector is due to ε.

Therefore, in the present invention, the sum of the roll gap change 8ε obtained from the detected sheet thickness deviation and the roll gap operation amount ΔSE by the roll eccentricity removal control is defined as the roll eccentricity amount, and the above-mentioned Fourier analysis is performed and the upper and lower backup rolls 2A ,
Detect roll eccentricity m and phase of 2B. This allows ε=
0, that is, the amount of roll eccentricity and phase are corrected so that the amount of change in plate thickness due to roll eccentricity is eliminated, and the plate thickness accuracy is improved.

Next, the roll diameter D of the upper and lower backup rolls 2A and 2B
If the difference between A and DB is small or absent, the above method cannot be adopted because no relative phase shift occurs between the upper and lower backup rolls 2A and 2B. Therefore, if the difference in diameter between the upper and lower backup rolls is small, it is detected as composite roll eccentricity of the upper and lower backup rolls. for example,
The composite roll eccentricity based on the mark pulse 2A of the upper backup roll is expressed as Δ3E=X-sin(θA+φ) (32)
becomes. X and φ in equation (29) are determined by Fourier analysis of the amount of change in the roll gap determined from the detected plate thickness deviation.

(Example) FIG. 1 is a block diagram showing one embodiment of the present invention.

The control device according to this embodiment has a pair of upper and lower workpieces 0-1.
A, 1B, a pair of upper and lower backup rolls 2A, 2B,
and a mark pulse transmitter 4A in a rolling mill equipped with a hydraulic reduction control device 6.

4B, sampling pulse transmitters 5A, 5B, rotation angle calculation means 11, plate thickness deviation detector 9, roll gap change amount calculation means 16, adder 22, speed detector 15, delay means 14, Fourier transform calculation means 21, A roll eccentricity reproducing means 12 and a delay compensation calculation means 13 are provided.

The Fourier transform calculation means 21 includes a calculation storage means 17 , a calculation means 18 , a Fourier transformer 19 , and a calculation means 20 .

The mark pulse generators 4A and 4B are provided on the upper and lower backup rolls 2A and 2B, respectively, and generate one pulse per rotation of each backup roll. Sampling pulse transmitters 5A and 5B are provided on upper and lower backup rolls 2A and 2B, respectively,
Each backup roll generates N pulses in one rotation. In other words, the mark pulse interval is divided into 1/N equal parts of 36
Outputs one pulse at a pitch of 0/N degrees.

The rotation angle detection means 11 includes mark pulse transmitters 4A and 4B.
Input the pulse signals of the sampling transmitters N5A and 5B and perform the upper and lower backup rolls 2A.

Calculate the rotation angles θ and θ of 2B.

B Rotation angles θ and θ detected by the rotation angle calculation means 11
B is output to the roll eccentricity reproducing means 12.

The roll eccentricity reproducing means 12 uses the roll eccentricity amplitudes X, X3, phase angles φA, φB1 calculated by the calculating means 20, and rotation angles θ, θ8 which are the outputs of the rotation angle calculating means 11.
Using equations (1), (2), and (3), the roll eccentricity ΔS is reproduced and output to the delay compensation calculation means 13. The delay compensation calculation means 13 mainly has a function of compensating for the response delay of the hydraulic pressure reduction control system, and when the transfer function of the hydraulic pressure reduction control system is GH(S) (S is a Laplace operator),
The delay compensation calculation means 13 calculates the formula (33),
The roll gap control amount ΔSC is output to the hydraulic pressure reduction control device 6.

As a result, the roll gap has a truly opposite phase to the roll eccentricity, and it is possible to improve the eccentricity removal accuracy.

The plate thickness deviation Δh detected by the plate thickness deviation detector 9 is
It is input to the roll gap calculation means 16 and converted into a roll gap change factor ε.

The output ΔSE of the roll eccentricity regeneration means 12 is sent to the delay means 14 to simulate the delay from the rolling mill to the plate thickness deviation detector 9. The speed of the rolled material 10 detected by the speed detector 15 is input to the delay means 14 in order to calculate the moving distance of the material.

The output ΔSE of the delay means 14 is the roll eccentricity removal control amount when the rolled material 10 located directly below the plate thickness deviation detector 9 is directly below the rolling mill, and is added to the output ε of the roll gap change amount calculation means 16. calculation storage means 17
is input.

The mark pulse and the sampling pulse are input to the arithmetic storage means 17, which stores the roll gap change amount (ε+ΔSE*) at each upper backup roll sampling pulse generation timing based on the mark pulse, and also stores the lower backup roll mark pulse. As a reference, the roll gap change amount (ε+ΔSE) is stored at each lower back-up roll sampling pulse generation timing. At the same time, the phase angle θ, θ between the upper and lower mark pulses. is calculated and stored using the mark pulse and sampling pulse of the input upper leakage back-up roll.

The calculation means 18 calculates θ stored by the calculation storage means 17.
, θ, and select θ such that α and β shown in equations (21) and ■ n (22) are, for example, 60″ or more.
・, 0 ・ θ Determine θ and θ1゜m+
nJ゛ nk゛ nJ) θ ・ Mark pulse IJ corresponding to θ and θ” nkλ n
l Sampling value Δ of roll eccentricity after the timing of occurrence of
S11. ΔS1j and ΔS ΔS21 are input from the calculation storage means 17, and the difference δ between ΔS11 and ΔS1j is
The difference δ2 between Δ8241 and ΔS2 is calculated and output to the Fourier transformer 19. The Fourier transformer 19 converts δ
, δ2 data is subjected to Fourier analysis, and the single amplitude of eccentricity x
, X and the phase angles θ and θ are outputted to the calculation means 20.

The calculation means 20 receives the signal θ1゜θ α from the calculation means 18.
, β, (27), (28), nk. (29), (30), the eccentric width XA, X8 and phase angle φ of the upper and lower backup rolls. .

φB is calculated and output to the roll eccentricity reproducing means 12.

Now, the 0-le eccentricity is lifted ΔS by the 0-le eccentric regeneration means 12.
Suppose that E is played. This roll eccentricity ΔSE is determined by the delay compensation calculation means 13 as a zero-le gap control amount ΔS.
c and is output to the hydraulic pressure reduction t, lj 60 device 6 to eliminate the influence of roll eccentricity.

The hydraulic pressure reduction control device 6 is a roll gap control IImΔSc.
Based on Backup Roll 2A.

2B, work rolls-A, and 1B are operated to cancel the influence of roll eccentricity on plate thickness variation of the rolled material 10.

Then, the plate thickness variation of the rolled material 10 becomes smaller, and this is detected by the plate thickness deviation detection means 9 after a certain time delay (
(Because the rolling mill and the plate thickness deviation detection means 9 are placed at a certain distance). This plate thickness deviation Δh is converted into a roll gap change amount ε by the roll gap change calculation means 16, and is output to the adder 22.

Further, the roll eccentricity amount ΔSE, which is the output of the roll eccentricity regeneration means 12, is input to the delay means 14, and is outputted from the delay means 14 after a certain time delay based on the speed of the rolled material detected by the speed detector 15. be done. This output ΔS is input to the adder 22, and the roll gap change amount calculation means 1
It is added to the output ε of 6. That is, the detected and calculated roll gap change amount ε and the calculated roll eccentricity Δ
The SE phases are matched and added.

The output of the adder 22 is sampled by the calculation storage means 17, the calculation means 18, the Fourier transformer 19 and the calculation means 20 at the output timing of the mark pulse transmitters 4A, 4B and the sampling pulse transmitters 5A, 5B. After conversion, O-ru eccentric single imaging width X,
8 and phase angle φ. , φ8 is output.

The roll eccentricity reproducing means 12 reproduces the roll eccentricity piece amplitude xA, x
B and the phase angle φ, the current rotation angle θ of the backup rolls 2A, 2B which is the output of the means to φB and the rotation angle performance. , θB, the roll eccentricity ΔS is reproduced with consideration also to the phase. As a result, the roll eccentricity regenerating means 12 uses the roll eccentricity piece amplitude X that had been used until then.
,XB and phase angles φ, ,φ, are updated.

Therefore, by repeating the above series of operations at certain intervals, the plate thickness variation Δh due to roll eccentricity can be made zero.

Although only the fundamental wave has been described above, roll eccentricity can be detected using the same concept for harmonic components, and its influence can be removed.

(Effects of the Invention) The rolling mill W control device according to the present invention can detect the eccentricity of the roll with high accuracy by performing Fourier analysis on the plate thickness deviation signal of the rolled material. Furthermore, by converting this into roll gap control and operating the roll gap of the rolling mill, the influence of roll eccentricity can be removed, and the plate thickness accuracy can be improved.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2 is a diagram showing the relationship between the eccentric waveform of the upper and lower backup rolls and mark pulses, and Figure 3 is a diagram showing the relationship between the rolling mill and the plate thickness deviation detector. FIG. 4 is a block diagram of a conventional control device that eliminates the influence of roll eccentricity based on a rolling load signal. 1A, IB... Work roll, 2A, 2B... Backup roll, 4A, 4B... Mark pulse transmitter, 5A, 5B... Sampling pulse transmitter, 6...
・In the hydraulic reduction control device, 9...plate thickness deviation detector, 10.
...Rolled material, 11...Rotation angle calculation means, 12...Roll eccentricity regeneration means, 13...Delay compensation calculation means, 14
...Delay means, 15. Speed detector, 16. Roll gap change amount calculation means, 17. Calculation storage means, 18.20. Calculation means, 19. Fourier transformer, 21... Fourier transform calculation means, 22... adder. Applicant's representative Sa knee - male UV Figure 2 Fan Figure 3

Claims (1)

[Claims] In a rolling mill equipped with a pair of upper and lower work rolls, a pair of upper and lower backup rolls, and a hydraulic reduction control device, a mark pulse transmitter that outputs one pulse per rotation provided on each of the backup rolls; a sampling pulse oscillator that outputs N pulses in one rotation, and a rotation angle calculation means that calculates the rotation angle of each of the backup rolls based on the outputs of the mark pulse oscillator and the sampling pulse oscillator; detecting the plate thickness of the rolled material on the output side of the rolling mill;
A plate thickness deviation detection means outputs the deviation between the detected plate thickness and the set value of the plate thickness of the rolled material, and the deviation detected by the plate thickness deviation detection means is converted into a roll gap change amount of the rolling mill. a speed detector for detecting the moving speed of the rolled material; a delay means; and an addition means for calculating the sum of the output of the delay means and the output of the roll gap change amount calculation means. , Fourier transform calculating means for calculating the eccentric amplitude and phase angle of the roll by sampling the output of the adding means at the output timing of the mark pulse transmitter and the sampling pulse transmitter and performing Fourier transform; Roll eccentricity reproducing means for reproducing the eccentricity of the roll based on the output of the means and the output of the rotation angle calculating means;
A roll gap control amount that converts the output of this roll eccentricity regeneration means into a roll gap control value and outputs a control signal to the hydraulic pressure reduction control device so as to cancel the amount of change in the roll gap due to the roll eccentricity of the rolling mill. converting means, and the delay means is configured to convert, based on the output of the speed detector,
A moving time of the rolled material between the roll of the rolling mill and the plate thickness deviation detecting means is calculated, and the output of the roll eccentricity regenerating means is delayed by the moving time and output to the adding means. A control device for a rolling mill.