JPS62292212A - Automatic shape control method for rolling mill - Google Patents

Abstract

PURPOSE:To restrain an increase of setting length accompanying with an increase of rolling velocity and to perform an automatic shape control with high accuracy by setting a proportional gain and an integral times of a controller according to the rolling velocity. CONSTITUTION:Based on the momentary rolling velocity (v) detected by a velocimeter 11, the proportional gain and the integral times of the controller 9a and 9b are calculated momentarily and set by a velocity correcting arithmetic device 12. In this way, a response time is reduced accompanying with the increase of the rolling velocity, an optimum response is allowed to get at each rolling velocity to perform the automatic shape control with high accuracy.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an automatic shape control method for a rolling mill that automatically controls the shape of a rolled material.

<Prior art> Fig. 4 is a block diagram of a four-high rolling mill that implements a conventional automatic shape control method, in which 1 is a rolling mill, 2 is a backup roll, 3 is a work roll, 4 is a roll bending device,
5 is a rolling device, 6 is a rolled material, 7 is a shape detector, 8 is a shape calculation device, and 9a and 9b are controllers, respectively.

According to this rolling mill, the rolled material 6 detected by the shape detector 7
From the elongation rate distribution in the board width direction, the 1st blowing component A1 and the 2nd water component A
2 is calculated by the shape calculation device 8. In addition, 1 water component AI and 2
As shown in the figure, water component A2 represents the magnitude of asymmetrical elongation and symmetrical elongation, respectively, and the method for determining these components A, A, from the elongation rate distribution in the sheet width direction is as follows: For example, a method using an orthogonal function as shown in Japanese Patent Application No. 60-97980, and a method using a power series as shown in Japanese Unexamined Patent Publication No. 55-194 are known.

Then, the above-mentioned 1-blow component A is
The pressure 1 device 5 is driven by the controller 9a so that the elongation rate on the drive side is large relative to the target value, and the pressure increase on the drive side is released. .

The controller 9b is controlled so that the first working forceps are pressed down so that A,=A,''.The controller 9b is also controlled so that the second blowing component A2 becomes the target value A29 (usually set as A2''=0).
to drive the roll bending device 4. For example, if the edge is slightly elongated with respect to the target value, the roll bending device 4 is driven in a direction to increase the convex crown of the work roll 3, and control is performed so that A2=A2'.

Incidentally, the controllers 9a and 9b are normally P■ controllers, and the proportional gain and integral time of the controllers 9a and 9b have conventionally been constant values.

<Problems to be Solved by the Invention> The conventional automatic shape control device described above has the following problems.

FIG. 5 is a block diagram showing the control system for the two-blow component A2, and 9b in the figure is the proportional gain Kp.

4 shows a control system of a PI controller having an integral time TI, and 4 shows a control system of a roll bending device. The control system 4 of the roll bending device controls the command to the roll bending device (i), the primary lag T representing the response of the shape change (component A2) to F, and the dead time due to the transfer delay from the rolling mill 1 to the shape detector 7. , constants K and S.

Here, the distance between the rolling mill 1 and the shape detector 7 is usually 2
~3m, so if the rolling speed is 100mpm, the dead time is 1.2~1.8secF? , degrees. Furthermore, since the time constant T is about 0.5 sec due to the responsiveness of the roll bending device 4, shape detector 7, etc., the control system shown in FIG. 5 is a system dominated by dead time when the rolling speed is low. . In such a control system, the proportional gain K of the PI controller 9b when the dead time is dominant
The optimum values of p and integration time T1 change depending on the dead time L (ie, rolling speed). - For example, the following methods are known to obtain the minimum settling time without overshoot or to obtain the minimum settling time with 20% overshoot.

However, in the conventional automatic shape control method, the proportional gain Kp and the integral time T.

Since is a constant value regardless of the rolling speed, 2 and T,
The value of should be set to the optimum value at the lowest rolling speed (maximum dead time) in view of the stability of the control system. Therefore, even if the rolling speed becomes high and the dead time becomes small, the response (settling time) is almost the same as at low speed, so the settling length (rolling speed/settling time) at high speed becomes longer, resulting in higher accuracy. There was a problem that automatic shape control could not be achieved. This situation also applies to the control of the one-blow component A.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a method for achieving highly accurate automatic shape control regardless of changes in rolling speed.

<Means for Solving the Problems> The automatic shape control method for a rolling mill according to the present invention automatically determines the shape of the rolled material by feeding back detection signals from a shape detector installed remotely on the downstream side of the rolling mill. The rolling mill to be controlled is characterized in that the rolling speed is detected and the proportional gain and integral time of the control system are set in accordance with the rolling speed.

<Function> When the proportional gain and integral time are set according to the rolling speed, the response time becomes shorter as the rolling speed becomes higher, and an optimal response can be obtained at each rolling speed.

<Example> An example in which the present invention is applied to a four-high rolling mill will be described with reference to the drawings.

FIG. 1 is a block diagram of a four-high rolling mill.

Incidentally, the same parts as in the prior art are given the same reference numerals, and redundant explanations will be omitted. In FIG. 1, 11 is a speedometer, and 12 is a speed correction calculation device. time T
, is calculated and set every moment.

Here, V is the standard rolling speed. , the optimal values of the proportional gain and integral time at the standard rolling speed Vo are Kp O
+ Ti O, there are several methods to obtain the proportional gain 2 and the integral time Ti from the rolling speed V as follows.

That is, Kp=Kpo・ □ ・・・・・・・・・・・・ (1
)O Kp” K po・, D[・・・・・・・・・・・・ (
2) O T + -T + o-door ・・・・・・・・・-(3
), the proportional gain Kp is increased in proportion to the rolling speed V or the square root of the rolling speed 6, and the integral time T is decreased in inverse proportion to the rolling speed V or the square root of the rolling speed - J''W. .Also, as shown in Fig. 2, there is a method of obtaining the relationship between the rolling speed V, the optimum proportional gain Kp, and the optimum integration time TI, which are obtained through experiments, using an approximate equation. How to ask.

- As an example, one-blow component A when the proportional gain and integral time T- are determined by equations (2) and (3).
Figure 3 shows the responsiveness of the control system of . In Figure 3,
Column a) shows the response when a step-like target value A+" with an amplitude of 2 x 10-' is manually applied to the control system of 1 water component A1 at rolling speed v = 100 mp111, and as shown in the enclosed graph, Dead time is 1.5 sec (transfer distance is 2.5 m) and 90% rise time is 7.5 sec.
It is c. Note that the constant KPo of the PI controller 9a at this time is K. In Fig. 3, b
) and C) columns are rolling speed v = 200 mpm, respectively.
, v = 400 mpm, and the 90% rise time is as short as 4.2 sec and 2.4 sec, respectively, which indicates that the correction by equations (2) and (3) is effective. It can also be seen that the correction using Equation 11 is more effective than Equations (4) and (5) for sailing speed. It is also clear that the correction using FIG. 2 is also effective.

In the second embodiment, the present invention is applied to a four-high rolling mill, but the present invention can of course be applied to other types of rolling mills.

<Effects of the Invention> According to the present invention, in an automatic shape control system in which dead time caused by transfer delay between a rolling mill and a shape detector is dominant, the proportional gain and integral time of the controller are adjusted according to the rolling speed. Since this setting is made, the response time can be shortened as the rolling speed increases. Therefore,
Settling length due to increase in rolling speed (Rolling speed/Settling time)
It is possible to suppress the increase in the number of shapes and achieve highly accurate automatic shape control.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a four-high rolling mill to which the present invention is applied;
The figure is a characteristic diagram showing the optimum proportional gain and optimum integration time with respect to rolling speed, Figure 3 is a detailed explanatory diagram of the present invention, and Figure 4 is a configuration diagram of a four-high rolling mill implementing the conventional automatic shape control method. , FIG. 5 is a block diagram showing a conventional control system. In the drawings, 1 is a rolling mill, 6 is a rolled material, 7 is a shape detector, 11 is a speedometer, and 12 is a speed correction calculation device.

Claims (1)

[Claims] In a rolling mill that automatically controls the shape of the rolled material by feeding back detection signals from a shape detector installed downstream of the rolling mill, the rolling speed is detected and the proportional gain and integral time of the control system are calculated. An automatic shape control method for a rolling mill, characterized by setting the shape according to the rolling speed.