JP2000084609A - Method and device for automatic plate thickness control of rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for automatically controlling the plate thickness of a rolling mill capable of automatically controlling a gain, preventing output from haunting based on the high gain and realizing high plate thickness precision. SOLUTION: In this automatic plate thickness control method in which an outlet side plate thickness deviation of a rolling material 7 is detected at the outlet side of a rolling mill 1, output X1 which is arithmetic-processed at a controller 8 based on a prescribed control action using this detected outlet side plate thickness value ΔH as an input signal, is inputted to a screw down controller 5 of the rolling mill 1 and a roll gap of the rolling mill is adjusted, by comparing the outlet side plate thickness deviation value and the output value X1 of the controller, when both cycles are synchronous, a control gain of the controller 8 is made smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for automatically controlling the thickness of a rolling mill.

[0002]

2. Description of the Related Art In the thin rolling of steel, aluminum, copper and the like, automatic thickness control is performed. This automatic thickness control is performed by measuring a delivery thickness deviation by a thickness gauge installed at a position away from a rolling position on a delivery side of a rolling mill, inputting the measurement result to a controller, and performing a predetermined measurement by the controller. (E.g., PI operation) to output a manipulated variable to control the rolling device of the rolling mill.

However, in this automatic thickness control, since the rolling position and the thickness deviation detection position are separated from each other, a detection delay time, that is, a dead time occurs, so that accurate control cannot be performed. Therefore, a high-accuracy control is performed by compensating for the dead time to realize high plate thickness accuracy. For example, Japanese Patent Publication No. 47-47983 and Japanese Patent Publication No. 3-63443 disclose such a technique. I have.

[0004]

In the above prior art,
In order to achieve higher plate thickness accuracy, a controller attempts to realize a high gain control system. However, when the gain is increased, the control system becomes vibratory, and the plate thickness accuracy is rather deteriorated. There was a problem of doing. Accordingly, the present invention provides an automatic thickness control method and an apparatus for a rolling mill capable of automatically controlling a gain, preventing output hunting based on a high gain, and achieving high thickness accuracy. Aim.

[0005]

In order to achieve the above object,
The present invention has taken the following measures. That is, the feature of the present invention is that the exit side thickness deviation of the rolled material is detected at the exit side of the rolling mill, and the detected exit side thickness deviation value is used as an input signal, and the controller performs the control based on a predetermined control operation. In the automatic thickness control method of adjusting the roll gap of the rolling mill by inputting the calculated output to the rolling device of the rolling mill, the output side thickness deviation value is compared with the output value of the controller. When the period is synchronous, the control gain of the controller is reduced.

That is, the fact that the fluctuation period of the detected value of the sheet thickness deviation of the rolled material and the fluctuation value of the output value of the controller coincide with each other means that the detected value acts as a disturbance. Means that the control gain is too high. Therefore, in such a case, the hunting of the output is prevented by automatically lowering the gain.

In the above method, it is determined whether or not the output side sheet thickness deviation value is oscillating, and when the output side sheet thickness deviation value is oscillating, the output side sheet thickness deviation value is compared with the output value of the controller. Is preferred. Further, the comparison between the output side sheet thickness deviation value and the output value of the controller is performed in consideration of a dead time based on the distance between the rolling position and the output side sheet thickness deviation detection position, and a cross-correlation coefficient between the two is obtained. When the correlation coefficient is larger than a predetermined value, it is preferable to determine that the periods match.

Further, the automatic thickness control apparatus for a rolling mill according to the present invention is characterized in that a thickness gauge for detecting an exit thickness deviation of a rolled material at an exit side of the rolling mill, and a thickness gauge based on the thickness gauge. A controller that outputs a manipulated value by performing arithmetic processing based on a predetermined control operation and outputs a manipulated value based on a detected value of the exit side plate thickness deviation as an input signal, A dead time calculating means for calculating a dead time based on a distance between the rolling position and the thickness gauge; and a dead time from the output from the controller, the detected value from the thickness gauge and the dead time from the dead time calculating means. It is characterized in that it comprises a judging means for judging whether or not the cycle of the detected value and the cycle of the output of the controller are synchronized, and gain control means for adjusting the gain of the controller based on the judging means.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a control system of a rolling mill. On both sides of the rolling mill 1, tension reels (rewinding / winding machines) 2, 2 are arranged to form a reverse type rolling equipment. On the exit side of rolling mill 1,
A thickness gauge 3 is provided at a distance L from the rolling position, and a rolling speed detector 4 is provided on the deflector roll. The rolling mill 1 is provided with a rolling reduction device 5 for adjusting a roll gap.

[0010] The control system has an automatic thickness control device 6 provided on the outlet side. In this example, the rolled material 7 moves to the right of the arrow, and the control system also adjusts to the moving direction. However, when the rolled material 7 moves in the direction opposite to the arrow shown in the figure, this control system is configured to operate on the outlet side. The automatic thickness control device 6 includes the thickness gauge 3
, And calculates the manipulated variable x1 based on a predetermined control operation (proportional operation, integral operation, differential operation, etc.), and outputs the manipulated variable x1 to the rolling-down control device 5. A controller (a PI controller in this embodiment) 8 is provided. This automatic thickness control device 6 is called a so-called monitor automatic thickness control (monitor AGC), and is constituted by a negative feedback system.

That is, the outlet thickness deviation value ΔH detected by the thickness gauge 3 is compared with the outlet thickness deviation set value ΔH ₀ by the comparator 9, and the result is inputted to the PI controller 8. ing. The PI controller 8 is provided with a gain control means 10 for increasing and decreasing the PI gain.

Further, the automatic thickness control device 6 has a comparator 11. The comparator 11 includes a PI controller 8
Output, that is, the roll gap command value x1, the exit side thickness gauge 3
And outputs the output side thickness deviation value ΔH and the rolling speed v output from the rolling speed detector 4 to the gain controller 10 of the PI controller 8 after performing predetermined processing. It is.

That is, the comparator 11 determines whether or not ΔH is oscillating. If it is oscillating, it compares x1 with ΔH, and if the periods match, the control gain of the PI controller 8 increases. It is determined that the time has passed, and a command to reduce the control gain to the PI controller 8 is output. More specifically, the comparator 11 has a dead time calculation unit 12, a vibration determination unit 13, a cross-correlation coefficient calculation unit 14, and a determination unit 15, and operates according to the flow shown in FIG.

That is, as a step, the output signal x1 of the PI controller 8 is read. Here, x1 is actually "x1 (i)" i = 1, 2, 3, 4,..., N, and reading is performed at regular time intervals Δt. In the step, the exit side plate thickness deviation value ΔH is read. Where ΔH is
Actually, “ΔH (j)” j = 1, 2, 3, 4,..., N, and reading is performed at regular time intervals Δt.

In the step, the exit rolling speed v is read. Here, v is actually “v (k)” k = 1, 2,
3, 4,... N, and reading is performed at regular time intervals Δt. In the step, the dead time calculating means 12 calculates the dead time tl (k). That is, since the distance from the rolling position to the thickness gauge 3 is an L meter, tl (k) = L / v (k).

The dead time is represented by x1 (i), i of ΔH (j),
An auxiliary operation for adjusting the phase of j, m = tl / Δt
Then, it can be expressed as i = j−m. In the step, the vibration judging means 13 judges whether or not the exit side plate thickness deviation value ΔH is vibratory. This determination is made based on whether or not the detected value ΔH of the thickness deviation periodically changes with time.

If it is oscillating, the gain of the PI controller 8 may be too large, so proceed to the next step. If it is non-oscillating, the gain of the PI controller 8 will not be too large. Return. In the step, it is checked whether or not the periods of x1 and ΔH match. This check is first performed by obtaining the cross-correlation coefficient φ between x1 and ΔH by the following equation by the cross-correlation coefficient calculation means 14.

[0018]

(Equation 1)

When the correlation function φ is larger than a certain value C, the judgment means 15 judges that the periods of x1 and ΔH are coincident. In this case, since the gain of the PI controller 8 needs to be reduced, the process proceeds to the next step. X1 and ΔH when the correlation function φ is smaller than a certain value C
Are determined not to match. In this case, the process returns to the step.

In the step, the gain of the PI controller 8 is reduced by about 10 to 20%. In the step,
If the calculation is stopped, the process proceeds to the end. If the calculation is continued, the process returns to the step. According to the embodiment of the present invention having the above configuration, in consideration of the dead time in the monitor AGC, which causes hunting of the control system, the roll gap command is issued when the exit side thickness deviation is oscillating. x1 is compared with the exit side sheet thickness deviation .DELTA.H of the rolled material 7 tracking the same.
Is automatically determined to be too large, and the control gain is reduced until it becomes non-oscillating.

Therefore, according to the present embodiment, rolling can be performed with the gain of the controller 8 set to the maximum, thereby improving the thickness accuracy. It should be noted that the present invention is not limited to the embodiments described above.

[0022]

According to the present invention, the hunting of the control system can be prevented in the automatic thickness control, and the gain can be maximized. It is possible to improve the follow-up performance in the acceleration / deceleration section, to speed up the convergence in the portion where the exit side plate thickness deviation is large, and to greatly reduce the off-gauge portion.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic thickness control device for a rolling mill according to the present invention.

FIG. 2 is a flowchart of an automatic thickness control method for a rolling mill according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolling machine 3 Thickness gauge 4 Rolling speed detector 5 Reduction control device 6 Automatic thickness control device 7 Rolled material 8 Controller 10 Gain control means 11 Comparator 12 Dead time calculation means 13 Vibration judgment means 14 Cross-correlation coefficient calculation means 15 Judgment means

Claims (4)

[Claims] 1. An output side thickness deviation of a rolled material is detected at an output side of a rolling mill, and an output processed by a controller based on a predetermined control operation using the detected output side thickness deviation value as an input signal, In an automatic thickness control method for adjusting a roll gap of a rolling mill by inputting to a rolling reduction device of a rolling mill, comparing the output side sheet thickness deviation value and an output value of the controller, the periods of both are synchronous. An automatic thickness control method for a rolling mill, wherein the control gain of the controller is reduced. 2. The method according to claim 1, further comprising: judging whether or not the output side plate thickness deviation value is oscillating, and comparing the output side plate thickness deviation value with an output value of the controller when the output side plate thickness deviation value is oscillating. The method for automatically controlling a thickness of a rolling mill according to claim 1. 3. The comparison between the output side sheet thickness deviation value and the output value of the controller is performed by taking into account a dead time based on the distance between a rolling position and an output side sheet thickness deviation detection position. 3. The method according to claim 1, wherein when the correlation coefficient is larger than a predetermined value, it is determined that the periods match. 4. A thickness gauge for detecting an exit thickness deviation of a rolled material at an exit side of a rolling mill, and a detected value of the exit thickness deviation from the thickness gauge as an input signal and based on a predetermined control operation. A controller that outputs a manipulated variable by performing arithmetic processing, a rolling-down control device that adjusts a roll gap of a rolling mill based on an output from the controller, and a wasteful time that calculates a dead time based on a distance between a rolling position and a thickness gauge. A time calculating means, an output from the controller, a detection value from the thickness gauge, and a dead time from the dead time calculating means, the detection value of the thickness gauge and the cycle of the output of the controller are synchronized. An automatic sheet thickness control device for a rolling mill, comprising: a determination unit configured to determine whether the controller is operating; and a gain control unit configured to adjust a gain of the controller based on the determination unit.