JPH0366044B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for automatically controlling the thickness of a rolled material in a rolling mill, and particularly relates to a feed-forward type thickness control method. be.

[Prior art] The method of automatic plate thickness control in a conventional rolling mill is as follows:
Generally, a feedback method is adopted. However, in the feedback method, it is difficult to perform highly accurate control without delay due to a time delay in the plate thickness detection signal or a time delay in the operating mechanism.

To solve this problem, feedforward control may be introduced.

Feedforward control of the rolling mill is performed as follows.

ΔS = (m/M) ΔH … (1) or ΔS = A (m/M) ΔH … (2) where ΔS: between rolls m: plastic constant of material M: mill constant ΔH: entrance side plate thickness deviation A : Correction coefficient (control gain value) The plate thickness deviation signal from the plate thickness gauge at the entrance of the rolling machine is multiplied by ΔS between rolls as shown in equation (1).
The plastic constant m and mill constant M of the material are constants for calculation and are set in advance, but the plastic constant m of the material changes depending on the temperature and degree of plastic working even for the same material. It is difficult to fully understand the reason.

Therefore, a control gain value A is provided as a correction coefficient,
The roll distance ΔS is calculated by equation (2), which is multiplied by the right side of equation (1), and control accuracy is improved by separately providing a means for automatically slightly correcting the value of the control gain value A. It's getting older.

An example of an automatic plate thickness control method for a rolling mill using feedforward control is shown in FIGS. 4 and 5.
FIG. 4 is a block diagram of a conventional automatic plate thickness control method for a rolling mill, in which 1 is a rolled material, 2 is an entry reel that supplies the rolled material 1, 3 is an exit reel that winds up the rolled material 1, and 4 is a rolling roll that rolls the rolled material 1.

5 is an entry side plate thickness meter that measures the thickness of the rolled material 1 before rolling and outputs it as an entry side plate thickness deviation, and 6 is an exit side plate thickness meter that measures the plate thickness of the rolled material 1 after rolling and outputs it as an exit side plate thickness deviation. In total, 7 is a pulse generator that detects the entrance speed of the rolling mill, and 8 is an output timing that delays the signal by a considerable amount of time in consideration of the running time between the entrance side plate thickness meter 5 of the rolled material 1 and the rolling roll 4. circuit,
9 is a rolling mill hydraulic pressure reduction control device that controls the thickness of the rolled material 1 by changing the distance between the rolls; 10 is a feedback control device that feeds back the integral amount of exit side thickness deviation to the rolling mill hydraulic pressure reduction device 9; The input side plate thickness deviation is temporarily stored, and when the same point of the rolled material 1 passes the output side plate thickness gage 6, the input side plate thickness deviation data and the data at that time are recalled by arithmetic processing of the signal of the pulse generator 7. This is a tracking circuit that outputs the output side plate thickness deviation value in pairs.

Reference numeral 12a denotes a control calculator which calculates the reduction amount and updates the control gain value in response to the measured value of the entrance plate thickness meter 5.The hardware is a control electronic computer consisting of a CPU, memory, etc., and the control program will be described later. However, a block diagram corresponding to the function is shown in FIG.

In Fig. 4, 13 is a numerical setting device for setting the value of M and m used in the above-mentioned formula (2), and 14 is a first computing device that receives the entry side plate thickness deviation ΔH and multiplies it by (m/M). , 15 is a second arithmetic unit that calculates the feed forward output amount ΔS by multiplying the control gain value A, 16 is a memory that holds the value of the aforementioned control gain value A, and 17 is an input in the tracking circuit 11. The value in the memory 16 is increased or decreased based on the entrance side plate thickness deviation and exit side plate thickness deviation at the same point of the rolled material that has become a side and exit side pair.
It is an AGC controller.

The flowchart of the control program of the computing unit 12a is shown in the fifth figure.
Shown in Figures a and b. This program mainly consists of main routines A51 to A51, which mainly perform AGC operations, which will be described later.
A60, and interrupt routines A61 to A63 which mainly perform the calculation of equation (2) above.

The procedure of this conventional automatic plate thickness control method is performed as follows.

A rolled material 1 is supplied from an input reel 2, rolled by a rolling roll 4, and wound onto an output reel 3. The entry side plate thickness deviation ΔH is input from the entry side plate thickness meter 5 to the calculator 12a. In the computing unit 12a,
The interrupt routine is started, and in step A61, the entry side plate thickness deviation ΔH is taken in. In step A62, constants m and M and the control gain value A are multiplied and divided by equation (2) to calculate the roll-to-roll distance ΔS, and in step A63, Send the roll interval ΔS to the output timing circuit 8.

The above roll interval calculated in the interrupt routine
After a delay time corresponding to the traveling time of the rolled material 1, ΔS is outputted as a signal by the output timing circuit 8 to the rolling mill hydraulic pressure reduction control device 9 to control the roll reduction amount.

Note that the feedback control is an open loop and cannot correct the zero point of the exit side plate thickness deviation, so the feedback control device 10 is also used.

Since the optimal value of the control gain value A differs depending on the material and dimensions of the rolled material 1, it is set and inputted prior to rolling as described later, and automatic gain adjustment is performed as an adjustment means during rolling.
Control (hereinafter referred to as AGC) is performed.

In this AGC method, for example, the exit side plate thickness deviation Δh measured by the exit side plate thickness gauge 6 and the input side plate thickness deviation ΔH are sequentially temporarily stored by the tracking circuit 11 so that the same point on the rolled material 1 is With the input side plate thickness deviation data ΔH recalled at the time of passing 6,
The purpose is to increase or decrease the value of the control gain value A based on both values.

This AGC operation is performed in the main routine A51 to A60 in the arithmetic unit 12a, and step A51 is the initial setting of the entire program.
The constants used to calculate formula (2) are set by keyboard input, etc., and in step A52 the input of the input side plate thickness deviation data ΔH recalled is waited for, in step A53 the exit side plate thickness deviation data Δh is read, and in step A54 it is output. If the absolute value of the side plate thickness deviation Δh is smaller than the dead band width E, do nothing and proceed to step A60.
The sign of the entrance thickness deviation ΔH is checked in step A55, and if it is positive, the sign of the exit thickness deviation Δh is checked in step A56, and if it is negative, the sign of the exit thickness deviation ΔH is checked.

In step A58, when the signs on the input and output sides are the same, the value of the control gain value A is increased by a fixed number, for example, 0.1, and in step A59, when the signs are different, the value of A is decreased by a fixed number, for example, 0.1.

At step A60, refer to the switches on the operation panel, and if the calculation is to be continued, return to step A52.

The AGC operations in steps A54 to A59 above are summarized as follows.

(1) If the absolute value of the exit plate thickness deviation Δh is less than the dead band value E, the control gain value A is not changed.

(2) If the absolute value of the exit side plate thickness deviation Δh is greater than or equal to the dead band value E, and the sign of the input side plate thickness deviation data ΔH and the sign of the output side plate thickness deviation Δh are the same, then the difference between rolls 〓ΔS
It is determined that the adjustment amount of
increase.

(3) If the absolute value of the exit side plate thickness deviation Δh is greater than the dead band value E, and the sign of the input side plate thickness deviation data ΔH and the sign of the output side plate thickness deviation Δh are different, it is determined that the adjustment amount of ΔS between rolls is large. , in order to reduce this, the control gain value A is decreased by a certain amount (for example, 0.1).

In this way, the excess or deficiency of the control gain value A set and held in the variable area is adjusted to obtain the optimal feedforward control operating point.

[Problem to be solved] In the conventional plate thickness control method described above, the control gain value A is adjusted to increase or decrease depending on the sign of the inlet side plate thickness deviation ΔH and the sign of the outlet side plate thickness deviation Δh. When an error occurs in tracking the deviation, the direction of increase/decrease in the control gain value A may be reversed, and the exit side plate thickness deviation may be increased instead.

However, since it is difficult in actual operation to always make the tracking error zero at various rolling speeds, it may not be possible to control the exit plate thickness with high accuracy.

The present invention is intended to solve the above-mentioned problems, and aims to provide an automatic plate thickness control method for a rolling mill that does not result in poor control results even if there is some tracking error.

[Means for Solving the Problems] The automatic plate thickness control method for a rolling mill of the present invention is such that when the average amplitude value of the plate thickness deviation on the outlet side of the rolling mill is not within a predetermined dead band value, the average amplitude value of the plate thickness deviation on the outlet side of the rolling mill is The present invention is characterized in that the feedforward control gain value is corrected depending on the direction of change in the ratio of the amplitude value to the average amplitude value of the entrance side plate thickness deviation before and after the passage of time.

[Operation] Assuming that the temporal variation of the entrance plate thickness deviation is a sine wave, the waveform characteristic value after tracking that changes depending on the presence or absence of a tracking error is only the phase, and the amplitude does not change.

This fact that the amplitude does not change is true even if the waveform is not a sine wave.

From the above-mentioned viewpoint, the present invention attempts to determine the control state based on the average amplitude value that is not subject to tracking errors, and the present invention attempts to determine the control state based on the average amplitude value that is not subject to tracking errors. (1) When the average amplitude value of the exit plate thickness deviation is sufficiently small (within the predetermined dead band value), it is determined that the plate thickness control is functioning well, and the current situation is continued. do. Or, (2) When the average amplitude value of the exit side plate thickness deviation is relatively large (not within the predetermined dead band value), the ratio of the average amplitude value of the exit side plate thickness deviation to the average amplitude value of the inlet side plate thickness deviation. The feed forward control gain value is increased or decreased by increasing or decreasing the control gain value depending on whether it has an increasing tendency or a decreasing tendency.

The amplitude value of the plate thickness deviation can be calculated accurately by calculating the interval standard deviation, but in the case of rolling control, since the sign and negative of the plate thickness deviation are nearly symmetrical, the amplitude value of the plate thickness deviation can be calculated using the root mean square,
Alternatively, the average calculated absolute value can be used as the average amplitude value.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. Note that the reference numerals already mentioned indicate the same parts, and the explanation will be omitted.

FIG. 2 is a block diagram of a control device according to an automatic plate thickness control method for a rolling mill as an embodiment, and numeral 12 calculates the rolling reduction amount and corrects the control gain value in response to the measured value of the entrance plate thickness meter 5. A control calculator 18 is an AGC that calculates a control gain value from the measured value of the inlet side plate thickness gauge 5 and the measured value of the outlet side plate thickness gauge 6 and outputs it to the memory 16.
It is a calculation controller.

1A to 1E are flowcharts showing the control operation of the AGC calculation controller 18.

Figure 1a is a flowchart of the main program, and in step A1, a dead zone value E is set.

In step A2, the average value of the entrance plate thickness deviation is calculated as the average amplitude value of the entrance plate thickness deviation.

In step A3, the average value of the exit plate thickness deviation is calculated as the average amplitude value of the exit plate thickness deviation.

In step A4, the plate thickness deviation attenuation rate Xj is calculated. This Xj is a determination value for determining whether to increase or decrease the control gain value A, and serves as an index of the degree of unsuitability of the control gain value A.

In step A5, it is determined whether the average value of the exit plate thickness deviation is within the dead zone E. When <E, that is, when it is within the dead zone, sufficient plate thickness accuracy has been obtained, so the control gain value A is not changed. Go to step A7 immediately.

In step A6, when ≧E, that is, when the dead zone E is not reached, and sufficient plate thickness accuracy is not obtained, the control gain value A is changed to improve the plate thickness accuracy.

In step A7, a decision is made as to whether to continue the calculation or not by referring to a switch on the operation panel. To continue, return to step A2. If you do not want to continue, proceed to the end and exit.

FIG. 1b is a flowchart of the first subprogram for calculating the average value of the entrance side plate thickness deviation, and in step A8, the input side plate thickness deviation ΔHi is read. That is, the signal from the entrance plate thickness gauge 5 is read at a predetermined sampling pitch.

In step A9, the entry side plate thickness deviation ΔHi is converted into an absolute value. This is preprocessing for calculating the average value in the next step.

ΔHi→|ΔHi| In step A10, the average value ΔH of the entrance side plate thickness deviation ΔHi is determined. Here, n is the number of samples.

= (1/n) (|ΔH ₁ | + | ΔH ₂ | +…+ | ΔHn |) Figure 1c is a flowchart of the second subprogram that calculates the average value of exit side plate thickness deviation, and Step A11 Now, by tracking the entrance side plate thickness deviation ΔHi using the signal from the pulse generator 7,
Find the point at which the material at the same point reaches the outlet thickness gauge 6.

In step A12, the inlet side plate thickness deviation ΔHi and the outlet side plate thickness deviation Δhi at the same point are read.

In step A13, the exit plate thickness deviation Δhi is converted into an absolute value.

Δhi→|Δhi| In step A14, the average value Δh of the exit plate thickness deviation Δhi is determined. Here, n is the same as the number of samples n in step A10.

= (1/n) (|Δh ₁ | + | Δh ₂ | +... + | Δhn |) Figure 1d is a flowchart of the third subprogram for calculating the plate thickness deviation attenuation rate Xj, and the steps are as follows: In A15, the plate thickness deviation attenuation rate is determined by the following formula from the average value of the thickness deviation on the entrance side obtained in step A10 and the average value of the plate thickness deviation on the exit side obtained in step A14.
Find Xj.

It can be said that the smaller the value of Xj=/Xj is, the more appropriate the value of the control gain value A is, and the smaller the exit side plate thickness deviation is.

In step A16, it is determined whether Xj is the first value _X1 . If Yes, there is no previous Xj, so the comparison of Xj > Xj _-1 , which is performed in step A17, cannot be performed. Return and proceed to step A7. If no, step
Proceed to A17.

FIG. 1e is a flowchart of the fourth subprogram for changing the control gain value A, and in step A17 it is determined that Xj>Xj _-1 . Xj _-1
is Xj that was previously calculated and temporarily stored.
It is determined whether the current plate thickness deviation attenuation rate Xj has become larger than the previous plate thickness deviation attenuation rate Xj _-1 , that is, whether the current outlet side plate thickness deviation has become worse than the previous one.

When the answer is “Yes”, it is when things have gotten worse and there is a step.
Proceed to A19. If no, it means that the patient has improved, so proceed to step A18.

In step A18, it is determined whether the previous control gain value was lowered. When Yes, the previous control gain value was lowered and the plate thickness deviation attenuation rate Xj became smaller. Furthermore, Xj
In order to reduce this, the control gain value A is lowered this time as well. Proceed to step A21.

When No, the previous control gain value A was increased and Xj became smaller. In order to further reduce Xj, the control gain value A is increased this time as well. Proceed to step A20.

Also in step A19, it is determined whether the previous control gain value A was lowered. When Yes, the previous control gain value A was lowered and Xj became larger. In other words, the thickness deviation on the exit side became larger and worse. Therefore, this time, the control gain value A is increased, contrary to the previous time. Proceed to step A20.

When No, the previous control gain value A was increased and the plate thickness deviation attenuation rate Xj became large. In other words, the thickness deviation on the exit side became larger and worse. Therefore, this time, the control gain value A is lowered, contrary to the previous time. Proceed to step A21.

In step A20, the control gain value A is increased by 0.02. The current control gain value A is obtained by adding 0.02 to the previous control gain value A. In this example, it is set to 0.02, but other values may be used. Return and proceed to step A7.

In step A21, the control gain value A is decreased by 0.02. The current control gain value A is obtained by subtracting 0.02 from the previous control gain value A. In this example, it is set to 0.02, but other values may be used. Return and step A7
Proceed to.

Here, the relationship between tracking error and average amplitude will be explained using a graph. FIG. 3 is a graph showing the relationship between the tracking error and the amplitude of the plate thickness deviation signal.

In Fig. 3, a is the entrance side thickness deviation signal, b is the exit side thickness deviation signal, c is the entrance side thickness deviation signal after tracking when tracking is normal, and d is the input side thickness deviation signal after tracking when there is a tracking error. This is the side plate thickness deviation signal. In addition, “+,” written below the horizontal axis
0,-'' are signs indicating the sign of the signal at that moment.

The conventional method of correcting the control gain value depends on the instantaneous sign relationship between the outgoing plate thickness deviation signal and the incoming plate thickness deviation signal, and determines whether c or d is used as the incoming plate thickness deviation signal. Therefore, the sign relationship is different, which causes abnormal operation.

The present invention is a method of comparing the average amplitude of the thickness deviation on the entrance side and the exit side. In Fig. 3, the entrance side thickness deviation signal c, after tracking when tracking is normal and when tracking is abnormal, It can be seen that the average amplitude of d is the same.

When the average amplitude is calculated as the average of the absolute values, the calculated average value will vary slightly depending on how the data collection section is taken, but this will not be a problem if it is several wavelengths or more.

The control device according to the automatic plate thickness control method for a rolling mill of this embodiment is configured as described above, and operates as described below.

The entry side plate thickness deviation signal ΔHi from the entry side plate thickness gauge 5 installed at the entrance side of the rolling mill is read every predetermined run of the rolled material, and the input side plate thickness deviation signal ΔHi is read at every predetermined run of the rolled material, and is temporarily held until the same point of the rolled material reaches the position of the exit side plate thickness gauge 6. After being memorized, it is output,
The average deviation value is calculated together with the exit side plate thickness deviation signal, and the input side plate thickness deviation average value and the output side plate thickness deviation average value are calculated.

The exit side plate thickness deviation average value is compared with a preset dead zone value E, and if it is smaller, the control condition is determined to be good, and there is no need to modify the control conditions, and the current state is maintained.

When the average outlet plate thickness deviation value is larger than the dead zone value E, the value of the ratio Xj between the average inlet plate thickness deviation value and the average outlet plate thickness deviation value is obtained as an index of the degree of unsuitability of the control gain value A, and this It is checked whether the value of Xj is increasing or decreasing. If the value of Change the gain value.

In this way, the control device of this embodiment allows
Even when there is a tracking error, the exit side plate thickness deviation does not become significantly large (hunting), and good exit side plate thickness accuracy can be obtained.

[Effects of the Invention] The automatic plate thickness control method for a rolling mill of the present invention is such that when the average amplitude value of the outlet plate thickness deviation of the rolling mill is not within a predetermined dead band value, the average amplitude value of the outlet plate thickness deviation and the inlet plate thickness deviation are Since the feedforward control gain value is corrected according to the direction of change in the ratio of the thickness deviation to the average amplitude value before and after the passage of time, it is not affected by tracking errors and allows highly accurate automatic thickness control. It can be implemented and has great effects in terms of both product quality and productivity.

[Brief explanation of drawings]

1A to 1E are flowcharts showing the operation of the AGC calculation controller of the control device according to the automatic plate thickness control method for a rolling mill in one embodiment, FIG. 2 is a block diagram of the control device in the same embodiment, and FIG. The figure is a graph showing the relationship between the tracking error and the amplitude of the plate thickness deviation signal.
The figure is a program diagram of a conventional automatic plate thickness control method for a rolling mill, and FIGS. 5a and 5b are flowcharts of a control program for a computing unit according to the conventional control method. 1...Rolled material, 2...Enter side reel, 3...Outlet reel, 4...Rolling roll, 5...Enter side plate thickness gauge,
6...Exit side plate thickness gauge, 7...Pulse generator,
8... Output timing circuit, 9... Rolling machine hydraulic pressure reduction control device, 10... Feedback control device,
12... Control calculator, 13... Numerical setting device, 1
4, 15...first and second arithmetic units, 16...memory, 18...AGC arithmetic controller.

Claims (1)

[Claims] 1. Incorporate the entry side plate thickness deviation at the entrance side of the rolling machine of the plate material to be rolled, and change the roll reduction amount using the result of multiplying the input side plate thickness deviation and a predetermined control gain value to flatten the plate thickness of the plate material. In an automatic plate thickness control method for a rolling mill that performs eid-forward control, when the average amplitude value of the outlet plate thickness deviation of the rolling mill is not within a predetermined dead band value, the average amplitude value of the outlet plate thickness deviation and the input plate An automatic plate thickness control method for a rolling mill, characterized in that the control gain value is corrected depending on the direction of change in the ratio of the thickness deviation to the average amplitude value before and after the passage of time.