JP5818511B2 - Automatic plate thickness control method - Google Patents

Description

The present invention relates to an automatic gauge control how.

As is well known, when cold rolling a rolled material such as a steel plate, a multi-stage rolling mill equipped with a pair of work rolls is used. On the other hand, when cold-rolling rolled materials such as stainless steel, titanium, special steel, copper, etc., a cluster group of multi-stage rolling mills (cluster rolling Is generally used.
When rolling a rolled material with a multi-stage rolling mill such as a cluster rolling mill, first, the plate thickness of the rolled material is measured, the roll gap is calculated based on the measured plate thickness, and the roll gap is controlled by a reduction device. The thickness of the rolled material is automatically controlled by

  Various techniques for controlling the plate thickness have already been developed. For example, Patent Document 1 discloses that a thickness deviation (referred to as a plate thickness deviation) is predetermined sampling when rolling a rolled material. The control gain value is calculated by using the obtained thickness deviation detected by the period, the reciprocal of the calculated control gain value is multiplied by the calculated roll gap, and the value obtained by the multiplication is reduced by the reduction device An automatic plate thickness control device that performs feedforward control by outputting to the above is disclosed.

  Patent Document 2 discloses an automatic plate thickness control apparatus that controls a plate thickness by sending a control signal to a main motor used for driving a work roll and feedforward controlling the rolling speed (number of rotations). A technique is disclosed in which the output timing of the control signal is accelerated by the time required for the response of the main motor.

JP-A-3-254309 JP-A-4-361816

The techniques disclosed in Patent Documents 1 and 2 have not yet reached the point where high-precision automatic plate thickness control can be realized.
As one of the causes, the measurement result of the plate thickness deviation used for the automatic plate thickness control includes a noise component in addition to the component due to the plate thickness variation. It is not easy to distinguish these noise components from components caused by fluctuations in plate thickness. If these noise components are superimposed on the plate thickness deviation signal used for automatic plate thickness control, It becomes difficult to control the plate thickness with accuracy.

The present invention has been made in view of the above-described problems, and performs automatic plate thickness control with high accuracy by using a plate thickness deviation in which noise components other than components caused by plate thickness fluctuations are eliminated. and to provide an automatic gauge control how capable.

In order to achieve the above-mentioned object, the following technical measures were taken.
The automatic sheet thickness control method of the rolling mill according to the present invention measures the sheet thickness deviation of the rolled material, calculates the roll gap of the work roll that rolls the rolled material based on the measured sheet thickness deviation, and calculates this An automatic sheet thickness control method for controlling a reduction device in accordance with a roll gap, measuring a sheet thickness deviation of a rolled material at at least two rolling speeds, and decomposing the measured sheet thickness deviation into frequency components. By comparing the frequency components at the at least two rolling speeds, a component that does not depend on the rolling speed is excluded as a noise component from the plate thickness deviation, and the rolled material is removed based on the plate thickness deviation from which the noise component is eliminated. The roll gap of the work roll to be rolled is calculated.

Preferably, the following (i) to (v) may be performed when eliminating the frequency components that do not depend on the rolling speed as noise components from the decomposed frequency components.
(i) “Rate of change in speed”, which is the rate of change in rolling speed before and after the change in rolling speed, is calculated.
(ii) The thickness deviation is measured before and after the rolling speed is changed, and the measured deviation is decomposed into frequency components.

(iii) Multiply the calculated frequency change rate by the frequency of each frequency component before the change in rolling speed to obtain a multiplication frequency component.
(iv) Focusing on each frequency component after the change in rolling speed, a frequency component equal to the multiplication frequency component obtained in (iii) is extracted.
(v) With respect to the extracted frequency component, the amplitude of the frequency component from which the noise component is eliminated is obtained by subtracting the amplitude before the rolling speed change from the amplitude after the rolling speed change.

Moreover, the most preferable form of the automatic sheet thickness control method of the rolling mill of the present invention is to measure the sheet thickness deviation of the rolled material, and to determine the roll gap of the work roll that rolls the rolled material based on the measured sheet thickness deviation. calculated, an automatic gauge control method for controlling a screw down device in accordance with the calculated roll gap, the rolling speed of the "before change" and "changed", the rolled material on one side of the rolling device the thickness deviation is measured by decomposing the measurement was thickness deviation into frequency components, and compares the frequency components in rolling speed of the decomposed the "before change" and "changed", the "change A component that does not depend on the rolling speed before and after the change is eliminated as a noise component from the thickness deviation, and a roll gap of the work roll that rolls the rolled material based on the thickness deviation from which the noise component is eliminated is defined. To calculate And butterflies.

According to the automatic gauge control how the present invention, by using a thickness deviation noise components other than the component due to the thickness variation is eliminated, it is possible to perform highly accurate automatic gauge control Become.

It is the schematic of a cluster rolling mill provided with the automatic plate | board thickness control apparatus. It is a block diagram which shows the automatic board thickness control apparatus of this invention. It is a flowchart which shows the automatic plate | board thickness control method of this invention. It is the figure which divided and showed the frequency component which decomposed | disassembled the thickness deviation measured before the rolling speed change into the noise component and the frequency component of the thickness deviation which does not contain noise. It is the figure which divided and showed the frequency component which decomposed | disassembled the thickness deviation measured after the change of the rolling speed into the noise component and the frequency component of the thickness deviation which does not contain noise. It is the figure which compared and showed the frequency component which decomposed | disassembled plate | board thickness deviation before and behind the change of a rolling speed.

Hereinafter, an embodiment of a rolling mill 2 provided with an automatic sheet thickness control unit 1 of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the rolling mill 2 according to the present embodiment is a cluster rolling mill configured by combining a plurality of upper and lower pairs of work rolls 3, intermediate rolls 4, and backup rolls 5. In the cluster rolling mill, the arrangement of each roll is like a bunch of straw in a side view. In the cluster rolling mill 6 shown in the figure, four intermediate rolls 4 (two above and below) are arranged around a pair of upper and lower work rolls 3, and six backup rolls 5 (up and down) are arranged around the intermediate roll 4. This is a 12-high rolling mill in which three pieces are arranged. The cluster rolling machine 6 cold-rolls rolled material W such as stainless steel, titanium, special steel, and copper into a thin plate material, and is required to perform automatic plate thickness control with high accuracy. Therefore, it is preferable to apply the automatic sheet thickness control method of the present invention to the cluster rolling mill. However, the rolling mill 2 to which the present invention is applied may be a cluster rolling mill other than 12 stages (for example, a 20-stage rolling mill) or a rolling mill other than the cluster rolling mill.

  The rolling mill 6 is provided with a reduction device 7 that changes a roll gap between the work rolls 3 and 3. Although not shown, the reduction device 7 includes a wedge that changes the roll gap between the work rolls 3 supported by the backup roll 5 and a moving mechanism (for example, a hydraulic cylinder) that moves the wedge. ing. The wedge is formed in a wedge shape, and is configured to move the backup roll 5 in the upward or downward direction by moving in the horizontal direction.

On the entry side (left side in FIG. 1) and the exit side (right side in FIG. 1) of the rolling mill 6, there are provided an unwinding reel 8 for unwinding the rolled material W and a take-up reel 9 for winding the rolled material W. It has been.
Furthermore, an entrance side thickness gauge 10 for measuring the thickness of the rolled material W is provided on the entry side of the rolling mill 6, and the thickness of the rolled material W is also measured on the exit side of the rolling mill 6. A side plate thickness meter 11 is provided. The entrance side thickness gauge 10 and the exit side thickness gauge 11 are configured by a non-contact type thickness gauge (for example, an X-ray thickness gauge). The reels 8 and 9 and the thickness gauges 10 and 11 have opposite functions when rolled in the opposite direction.
Furthermore, the rolling mill 2 has an automatic sheet thickness control unit 1 that controls the roll gap between the upper and lower work rolls 3. The automatic plate thickness control unit 1 includes a feedforward control unit 12 and a feedback control unit 13, and is configured by an electrical control device such as a process controller, a sequencer, and a PLC.

The rolling mill 2 described above is rolled by passing the rolled material W between the work rolls 3, and at that time, the automatic sheet thickness control unit 1 controls the roll gap between the upper and lower work rolls 3. Thus, the rolled material W having a desired thickness can be rolled.
As shown in FIG. 2, the feed forward control unit 12 of the automatic plate thickness control unit 1 conceptually includes an input side plate thickness deviation tracking unit 14, an output timing adjustment unit 15, an output amount calculator 16 and a multiplier 17. It is configured. However, these means do not need to be physically independent devices, and only need to have these functions.

  In the feedforward control unit 12, first, the input side plate thickness deviation tracking means 14 causes the input side plate thickness gauge 10 to perform the predetermined sampling cycle Ts based on the pulse signal generated by the pulse generator 18 connected to the input deflector roll. An entrance-side plate thickness deviation ΔHi, which is the difference between the measured plate thickness Hi of the rolled material W and the set plate thickness Hs, is captured and held. Thereafter, when the position (measurement point) on the rolled material W corresponding to the measurement point arrives immediately below the work roll 3, the input side sheet thickness deviation ΔHi is output from the output timing adjusting means 15, and similarly, the output amount calculator 16 outputs a coefficient based on the mill constant of the rolling mill. Both outputs are multiplied by a multiplier 17 to calculate a roll gap change amount ΔS (roll gap change amount) for correcting the entry-side plate thickness deviation ΔHi and output it as a command value to the reduction device 7.

The control performed by the feedforward control unit 12 is normally employed in the automatic plate thickness control technique, and is a technique disclosed in, for example, Japanese Patent Application Laid-Open No. 3-254309.
Since this feedforward control is an open loop, the excess / deficiency of the correction amount is measured by the outlet side thickness gauge 11 and feedback control based on the measured value is also used in the feedback control unit 13.

By the way, as shown in FIGS. 1 and 2, the automatic plate thickness control unit 1 of the present invention includes an input side plate thickness deviation correction calculation unit 19 between the feedforward control unit 12 and the input side plate thickness meter 10. It is characterized by being.
The entrance side thickness deviation correction calculation unit 19 decomposes the thickness deviation based on the entrance side plate thickness measured by the entrance side thickness gauge 10 into frequency components, and the value after once removing the noise component in the frequency space. Is input to the feedforward control unit 12 (entrance side thickness deviation tracking means 14).

Hereinafter, the characteristics of the signal processing in the entry side thickness deviation correction calculation unit 19, in other words, the automatic plate thickness control method of the present invention will be briefly described with reference to FIGS.
4 and 5 show the concept of the processing of the present invention.
That is, as shown in FIG. 4 (a), when decomposed into frequency components by FFT processing thickness at entrance side deviation [Delta] H _A taken from the entry side thickness gauge 10, the five [P1] ~ [P5] Assume that a frequency component is obtained. These five frequency components include the frequency components (true thickness deviation) [P6] and [P7] of the plate thickness deviation not including noise shown in FIG. 4B and the noise component [P] shown in FIG. P8] to [P11]. That is, if attention is paid to [P2] in FIG. 4A, the amplitude is the sum of the amplitude of [P6] in FIG. 4B and the amplitude of FIG. 4C [P9]. Only the result of [P2] obtained as data cannot be separated into [P6] and [P9] (only the noise component is extracted).

On the other hand, FIG. 5 shows the frequency component (FFT processing result) of the entry side plate thickness deviation ΔH _B obtained when the rolling speed of the same rolled material W as in FIG. 4 is changed, for example, twice. The FIGS. 5 (a) As is apparent from, and a four frequency components of the frequency components of the entry side thickness deviation [Delta] H _B also like the _{ΔH A [P12] ~ [P15} ]. Focusing on the noise component shown in FIG. 5 (c), [P18] to [P21] have the same amplitude and frequency as in FIG. 4 (c), but include the noise shown in FIG. 5 (b). If attention is paid to the frequency component (true plate thickness deviation) of the plate thickness deviation that is not present, the generated frequencies of [P16] and [P17] are different from those in FIG.

  That is, the frequency component of the plate thickness deviation not including these noises has a generated frequency twice as the rolling speed changes twice. In other words, regarding the frequency component of the thickness deviation, “The frequency of the frequency component of the thickness deviation that does not include noise changes at the same rate of change (10Hz → 20Hz, 15Hz → 30Hz) according to the rate of change of the rolling speed. The frequency of the noise component does not change with the same rate of change even if the rolling speed changes. Therefore, if this characteristic is used, it is possible to extract only the frequency component of the plate thickness deviation that excludes the noise component and does not include the noise.

However, since the noise components shown in FIGS. 4C and 5C are actually unknown and are not understood, in the present embodiment, in the following procedure (S1 to S11 in FIG. 3), The frequency component of the plate thickness deviation not including noise (true plate thickness deviation), in other words, the corrected plate thickness deviation is extracted. The processes of S1 to S11 in FIG.
First, in S1 of FIG. 3, the rolling speed V of the rolled material W is measured. The measurement of the rolling speed V may be calculated based on the rotation speed of the work roll 3, or may be measured using a speed sensor or the like. Here, a case is considered where the rolling speed V = 100 mpm is measured based on the rotation speed of the work roll 3 (more precisely, the intermediate roll 4 of the work roll 3). After the rolling speed V is thus measured, the process proceeds to S2.

Next, in S <b> 2, the plate thickness at the entry side of the rolled material W is measured using the entry side plate thickness meter 10. Thereafter, by subtracting the set plate thickness Hs from a thickness which is measured to calculate the thickness at entrance side deviation [Delta] H _A. Note that this thickness at entrance side deviation [Delta] H _A, the noise component is contained in a inseparable state. Therefore, the process proceeds to S3, to decompose the thickness at entrance side deviation [Delta] H _A into frequency components, separating the noise component by utilizing the characteristics described above in a state of being decomposed into frequency components.

In S3, performs FFT processing on the entry side thickness deviation [Delta] H _A calculated in S2, is divided into frequency components. Here, entry side thickness deviation [Delta] H _A, as shown in FIG. 6 (a), is divided into five frequency components of [P1] ~ [P5].
[P1] Amplitude 0.01μm, Frequency 1Hz
[P2] Amplitude 0.83μm, Frequency 10Hz
[P3] Amplitude 0.90μm, frequency 15Hz
[P4] Amplitude 0.04μm, Frequency 20Hz
[P5] Amplitude 0.02μm, frequency 30Hz
The entry side thickness deviation [Delta] H _A is as shown in equation (1) is used the above-described [P1] ~ [P5].

Incoming side thickness deviation ΔH _A = 0.01sin (2π × 1 × t) + 0.83sin (2π × 10 × t) + 0.9sin (2π × 15 × t)
+ 0.04sin (2π × 20 × t) + 0.02sin (2π × 30 × t) (1)

Once this way entry side thickness deviation [Delta] H _A is divided into respective frequency components, the process proceeds to S4.

In S4 of FIG. 3, it is determined whether “the rolling speed V of the rolled material W has been changed” measured in S1.
Specifically, whether a change in the rolling speed V of the rolled material W is taken in every predetermined sampling period Ts, and whether there is a change more than a predetermined change amount between the measurement results of the continuously taken rolling speed V. Judging. When the rolling speed V changes by a predetermined change amount or more, it is determined that “the rolling speed V has been changed” and the process proceeds to S5. When the rolling speed V is less than the predetermined change amount, “the rolling speed V has been changed. It is determined that there is not, and the process returns to the beginning of S4.

  In S5, the change rate of the rolling speed is calculated with the changed rolling speed as V '. That is, when the rolling speed V ′ = 200 mpm of the rolled material W is measured in the same manner as S1, the change in rolling speed is measured using the measured rolling speed V ′ and the rolling speed V measured in S1. The magnification (rate of speed change) is calculated as (change magnification) = V ′ / V = 2.0. When the change rate V '/ V of the rolling speed is obtained in this way, the process proceeds to S6.

In S6, the thickness deviation is measured again with respect to the changed rolling speed. That is, the entry side thickness deviation ΔH _B is calculated in the same procedure as in S2. The entry side plate thickness deviation ΔH _B calculated in S6 in this way is also included in a state where the noise component cannot be separated. Therefore, the process proceeds to S7 so that the noise component can be easily removed, and the entry side plate thickness deviation ΔH _B is set. FFT processing is performed to separate the frequency components.

In S7, as in S3, the entry-side plate thickness deviation ΔH _B measured in S6 is separated into frequency components by FFT processing. Here, as shown in FIG. 6B, the entry side thickness deviation ΔH _B is separated into four frequency components [P12] to [P15].
[P12] Amplitude 0.01μm, Frequency 1Hz
[P13] Amplitude 0.03μm, frequency 10Hz
[P14] Amplitude 0.84μm, Frequency 20Hz
[P15] Amplitude 0.92μm, frequency 30Hz

That is, the entry side plate thickness deviation ΔH _B is expressed as in equation (2).

Entry side thickness deviation ΔH _B = 0.01sin (2π × 1 × t) + 0.03sin (2π × 10 × t)
+ 0.84sin (2π × 20 × t) + 0.92sin (2π × 30 × t) (2)

When this way is thickness at entrance side deviation [Delta] H _B is divided into respective frequency components, measured proceeds to S8, comparing the frequency components of the entry side thickness deviation [Delta] H _A frequency component and thickness at entrance side deviation [Delta] H _B To do.

In S8, “the generation frequency of the frequency component of the thickness deviation not including noise changes at the same change rate according to the change rate of the rolling speed, but the generation frequency of the noise component is the same even if the rolling speed changes. Using the characteristic that “the rate of change does not change”, the noise component is separated from the obtained frequency component, and only the frequency component of the plate thickness deviation not including noise is extracted.
Specifically, attention is first focused on the change rate (speed change rate) of the rolling speed. Since in the above example is the change ratio V '/ V = 2.0, the frequency 1Hz frequency components of the entry side thickness deviation [Delta] H _A occurs, 10Hz, 15Hz, 20Hz, to 30 Hz (see FIG. 6 (a)) The Multiply by the speed change rate (2.0 times) to obtain frequencies of 2Hz, 20Hz, 30Hz, 40Hz, 60Hz (multiplication frequency component). It is checked whether the frequency component of the entry side thickness deviation ΔH _B is generated at the obtained frequency.

As shown in FIG. 6B, the frequency components of the entry side thickness deviation ΔH _B after the rolling speed is changed are generated at frequencies of 1 Hz, 10 Hz, 20 Hz, and 30 Hz. Therefore, the frequencies of 20 Hz and 30 Hz are used. since but corresponds to "those frequency components of the entry side thickness deviation [Delta] H _a is obtained by multiplying the fold change in frequency generated (multiplied frequency components)", to extract these frequency components.
That is, the frequency component of the plate thickness deviation that does not include noise is included in [P14] of the frequency 20 Hz and [P15] of the frequency 30 Hz. However, since there are many possibilities that noise components are included in [P14] and [P15], the process proceeds to S9 to eliminate the noise components.

In S9, only the noise component is excluded from the entry side plate thickness deviation ΔH _B. That is, in FIG. 6A, attention is paid to frequency components generated at positions of 20 Hz and 30 Hz. If these frequency components are not noise components, they should occur at the multiplication frequencies of 40 Hz and 60 Hz. However, no frequency component is generated at 40 Hz or 60 Hz. That is, the frequency component generated at 20 Hz or 30 Hz in FIG. 6B is nothing but a noise component. Therefore, by subtracting the amplitudes of [P4] and [P5] from the amplitudes of [P14] and [P15], the frequency component of the thickness deviation that does not contain noise (as shown in equation (3)) is obtained. Can be obtained.

Thickness deviation without noise ΔH = 0.84sin (2π × 20 × t) + 0.92sin (2π × 30 × t)
-0.04sin (2π × 20 × t) -0.02sin (2π × 30 × t)
= 0.80sin (2π × 20 × t) + 0.9sin (2π × 30 × t) (3)

In this way, if the sheet thickness deviation ΔH from which the noise component is eliminated is input to the feedforward control unit 12 to control the roll gap ΔS, the influence of the noise component is surely eliminated and highly accurate automatic sheet thickness control is performed. Can be performed.

In this way, the plate thickness deviation ΔH from which the noise component has been eliminated in S10 is input as a “corrected plate thickness deviation” to the feedforward control unit 12 (incoming plate thickness deviation tracking means 14), and the roll gap change amount ΔS is input. If controlled, it is possible to reliably eliminate the influence of noise components and perform highly accurate automatic plate thickness control.
In S11, it is determined whether or not the processes in S1 to S10 described above are performed again. The processes of S1 to S10 can be performed every time when the rolling speed is changed a plurality of times, and noise can be eliminated each time, and more accurate automatic plate thickness control can be performed.

  By the way, although the process of above-mentioned S1-S11 was an example whose change rate of a rolling speed is 2 times, it is not necessary to actually change a rolling speed so that a change rate becomes 2 times. Further, this process may be performed, for example, when a speed change occurs during rolling, that is, when one rolled material W is accelerated or decelerated. This process may be performed in advance to obtain noise components (waveforms and amplitudes corresponding to FIGS. 4C and 5C) in advance.

In summary, in the entry side thickness deviation correction calculation unit 19,
(i) Calculate the "speed change rate", which is the ratio of the change in rolling speed before and after the change in rolling speed,
(ii) For each of the rolling speed before and after the change, measure the deviation of the sheet thickness and decompose the measured deviation into frequency components;
(iii) Multiply the calculated frequency change rate by the frequency of each frequency component before the change in rolling speed to obtain a "multiplication frequency component".
(iv) Focusing on each frequency component after the change of the rolling speed, extracting a frequency component equal to the multiplication frequency component obtained in (iii),
(v) For the extracted frequency component, subtract the amplitude before the rolling speed change from the amplitude after the rolling speed change to obtain the amplitude of the frequency component from which the noise component has been eliminated.
By performing the process, it is possible to obtain the plate thickness deviation ΔH from which the noise component is eliminated, and to perform automatic plate thickness control with high accuracy.

In the said embodiment, although the plate | board thickness deviation in two different rolling speeds was measured, you may measure by measuring three or more rolling speeds.
In the above-described embodiment, matters not explicitly disclosed, for example, operating conditions and operating conditions of the rolling mill, various parameters, dimensions, weights, volumes, etc. of the components are usually implemented in this technical field. It is sufficient to adopt a certain value.

DESCRIPTION OF SYMBOLS 1 Automatic sheet thickness control part 2 Rolling mill 3 Work roll 4 Intermediate roll 5 Backup roll 6 Rolling mill (cluster rolling mill)
DESCRIPTION OF SYMBOLS 7 Rolling device 8 Unwinding reel 9 Take-up reel 10 Incoming side thickness gauge 11 Outlet side thickness gauge 12 Feed forward control part 13 Feedback control part 14 Incoming side thickness deviation tracking means 15 Output timing adjustment means 16 Output amount calculator 17 Multiplier 18 Pulse generator 19 Entry side thickness deviation correction calculation section W Rolled material

Claims (2)

Automatic plate thickness that measures the thickness deviation of the rolled material, calculates the roll gap of the work roll that rolls the rolled material based on this measured thickness deviation, and controls the reduction device according to the calculated roll gap A control method,
In rolling speed of "before change" and "changed", the thickness deviation of the strip is measured on one side of the rolling apparatus to decompose the the measured thickness deviation into frequency components,
By comparing the frequency components in rolling speed of the decomposed the "before change" and "changed", thickness of the component that does not depend on the rolling speed of the "before change" and "changed" as a noise component Eliminate from deviation,
An automatic plate thickness control method characterized in that a roll gap of a work roll for rolling the rolled material is calculated based on a plate thickness deviation from which the noise component is eliminated. 2. The automatic sheet thickness control method according to claim 1, wherein the following (i) to (v) are performed when a component that does not depend on the rolling speed is excluded as a noise component from the decomposed frequency component.
(i) “Rate of change in speed”, which is the rate of change in rolling speed before and after the change in rolling speed, is calculated.
(ii) The thickness deviation is measured before and after the rolling speed is changed, and the measured deviation is decomposed into frequency components.
(iii) Multiply the calculated frequency change rate by the frequency of each frequency component before the change in rolling speed to obtain a multiplication frequency component.
(iv) Focusing on each frequency component after the change in rolling speed, a frequency component equal to the multiplication frequency component obtained in (iii) is extracted.
(v) With respect to the extracted frequency component, the amplitude of the frequency component from which the noise component is eliminated is obtained by subtracting the amplitude before the rolling speed change from the amplitude after the rolling speed change.