JPS61144208A - Control method of meandering in rolling mill - Google Patents

Abstract

PURPOSE:To prevent the meandering of a rolling stock while stably correcting the amount of off-center by detecting the difference between the amount of off-center and rolling reduction of a rolling stock and adjusting the difference in rolling reduction by using both detected values. CONSTITUTION:Rolling-load detectors 20, 22 are provided to both ends of a lower backup roll 18, and their outputs are inputted to an adder 24 and a subtractor 26 respectively. The adder 24 outputs the load sum of rolling rolls at the driving and operating sides and the subtractor 26 outputs the load difference between them, to an arithmetic and control unit 28. On the other hand, rolling reduction devices 30, 32 with rolling-reduction detectors are provided to both ends of an upper backup roll 18, and the outputs of them are inputted to an subtractor 34. The difference in rolling reduction between both ends of an upper backup roll 16 i.e. the amount of leveling is outputted to the unit 28 to operate the amount of off-center as well as to estimate the internal variables of meandering phenomenon, and the sum of the estimated value and the amount of off-center multiplied respectively by a gain i.e. the changing amount of leveling is operated to output the results to the devices 30, 32 in order to correct the amount of off-center.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling meandering of a rolled material in a rolling mill for rolling steel plates.

More specifically, by operating the rolling devices on the driving side and operating side of the rolling mill independently on both sides to create a difference in the amount of rolling, the meandering and rolling of the rolled material can be prevented.
In particular, the present invention relates to a method of preventing meandering at the rear end of a rolled material.

BACKGROUND OF THE INVENTION Conventionally, meandering of materials on a rolling line has been a problem since it not only impairs the dimensional accuracy of rolled products but also damages equipment attached to the rolling mill.

However, there is no suitable method for detecting meandering in a rolled material, and the method has relied on visual inspection and manual operation.

In recent years, attempts have been made to automate this, and various methods have been proposed. In this process, the deviation in the running position of the rolled material, that is, the off-center amount, is detected based on the difference in load between the drive side and the operation side of the rolling mill (hereinafter referred to as differential load), and the roll gap difference between the drive side and the operation side (hereinafter referred to as differential load) is detected. A method for adjusting the leveling (hereinafter referred to as leveling) is disclosed in Japanese Patent Application Laid-Open No. 160817/1983. However, according to this method, in addition to the load difference caused by the off-center of the rolled material, the load difference caused by leveling is added, making control complicated and difficult to apply to actual rolling control.

In addition, leveling can be adjusted by detecting the off-center amount of rolled material at the entrance of the rolling stand using an optical detection method, or by installing a pressure detector on the artificial side guide of the rolling mill and using the contact force between the side guide and the rolled material. Detects the off-center amount of rolled material and adjusts leveling.
A method for correcting off-center I is disclosed in Japanese Patent Application Laid-Open No. 51-50263.
It is disclosed in the publication No.

In any of the above methods for detecting the amount of off-center, it is not possible to stably correct the amount of off-center by simply adjusting the leveling in proportion to the amount of off-center. It is not possible to prevent the rear end from meandering.

That is, ``Meandering of the rolled material occurs particularly at the rear end, and when it is severe, the end of the material is pressed against the side guide and rolled in a triple bite state, damaging the rolls and stopping the mill line. This may cause serious problems such as

Regarding this, JP-A-56-160817 states:
As shown in the schematic control system diagram of FIG. 2, it has been proposed to use a differential element to differentiate the off-center amount and determine the leveling correction amount to perform stable control. However, as is well known, the method using differential elements cannot operate normally in a noisy system. In particular, in the method described in the publication that uses rolling force for human control, the frequency of 3 to 20 Hz
There are rolling load fluctuations due to roll eccentricity, and the use of differential elements is practically difficult.

Problems to be Solved by the Invention As stated above, the method of controlling the meandering of the rolled material by knowing the off-center amount of the rolled material based on the differential load and controlling the off-center amount is difficult because the differential load is applied due to leveling. Moreover, the control was complicated, and it was not possible to follow rolling load fluctuations, making effective meandering control impossible.

Therefore, the present invention solves the problems of the prior art described above, and
Using the off-center amount detection value and the leveling amount detection value,
The object is to provide a method for stably controlling the amount of off-center by adjusting the leveling.

A means for solving the problem, that is, according to the present invention, is to control the off-center amount of the rolled material by operating the rolling devices on the driving side and the operating side of the rolling mill that rolls the steel plate, respectively, and making a difference in the rolling amount. In this method, the amount of off-center is detected and the difference in the amount of reduction is detected, the internal variables of the meandering phenomenon are estimated from these two signals, and a gain is applied to the estimated value and the amount of off-center, respectively. Provided is a meandering control method characterized in that the difference in the amount of rolling reduction is controlled based on the sum of the sum of the values multiplied by .

Function The method for controlling the meandering of a rolled material as described above is shown in a control system diagram as shown in FIG. As can be seen from FIG. 1, the off-center amount y and the leveling amount S df of the rolled material are detected, and based on these, the internal state estimated value 2 is estimated by, for example, an observer. The estimated internal state value 2 is expressed by the following equation.

2=λy+I ...(1) Here, ...(2) β is a constant determined by the rolling conditions, ■ is the speed at which the rolled material enters the rolling mill, λ is any positive value, and, for example, , a leveling amount change value U is determined from the off-center amount y and the above-mentioned internal state estimated value 2 using the optimum regulator. The leveling amount change value U is expressed by the following equation, assuming that the control gain is 1 and K2.

u=Kl-202.y (3) Thus, control is possible without a differential term, and control is possible without being affected by alternating current disturbances.

PRINCIPLE OF THE INVENTION Next, before describing embodiments of the method for controlling meandering of a rolled material according to the present invention, the present invention will be explained in detail.

First, the meandering function will be explained with reference to FIG. In FIG. 3, the rolled material 1 is moved by the arrow 3 by the pair of work rolls 2.
The figure shows the state of being rolled in the direction of . In the figure, the X-axis indicates the rolling direction coordinate, and the y-axis indicates the sheet width direction coordinate. Therefore, if the entrance speed of the rolled material 1 into the rolling mill is V, the rotational speed on the plate surface of the rolled material is ω, and the plate width of the rolled material is b, the following equation holds true.

vb v b v Here, the subscript indicates the operating side, and the subscript indicates the driving side (the same applies hereinafter).

By the way, if the roll circumferential speed is ■ and the backward movement rate is ψ, then the following equation (5) holds true.

■=(1+ψ)■...(5)vW
=(1+ψ,)■...(5).

VD= (1+ψ.)■ ・ ・
(5)'' Therefore, from equation (4), the following holds true. By the way, if the thickness difference in the sheet width direction at the roll exit side, that is, the amount of the thickness wedge of the plate is hdf, then The amount hdf is the leveling amount Sdf
and the off-center amount y, it can be expressed by the following formula.

On the other hand, the off-center amount y at time t can be expressed as follows using the rotational angular velocity ω and the entrance velocity V of the rolled material.

1y
(t)= ,l” ω(τ)(vt-vr)di I
＠α口If we differentiate this with respect to time t, we get (8) (9) (11) from Equation 2. Here, g) h dr ′ay From Equation (12), the meandering phenomenon is doubly an integral element. It can be seen that the control is extremely unstable as is well known.

The present inventor came up with the idea of implementing the control method for the above as follows.

If we express Equation (12) in a state space, we get: Therefore, the state X is estimated from the human power U and the output y using an observer. Letting the estimated value of x2 be Z, Z is given by the following formula.

At this time, from equations (15), (16), and (17), d Therefore, if λ〉0, It is. Also, from equation (15), xl is equal to y.

Therefore, by setting hdr Sdf as the command value of the leveling amount, stable control by state feedback can be realized. This command value S df is the leveling amount change amount U.

Here, as a method for determining the feedback gain of 1 and K2, for example, an optimal regulator method may be used.

That is, J'(y2(t)+ru"(t))dt-"
. . . 1, K2 may be obtained by a known method for the gain that becomes (20).

EXAMPLE Hereinafter, a meandering control method according to the present invention will be explained with reference to the accompanying drawings.

FIG. 4 shows a control device for a rolling mill that implements the meandering control method according to the present invention. In FIG. 4, the rolled material 10
are routed between work rolls 12 and 14, which work rolls 12 and 14 respectively are backed up by backup roll 1.
6 and 18 are pressed and supported. Rolling load detectors 2 are installed at both ends of the lower back-up roll 18.
0 and 22 are provided, and the outputs of the rolling load detectors 20 and 22 are input manually to an adder 24 and a subtracter 26. Therefore, the adder 24 outputs the sum of the loads P on the drive side and the operation side of the mill roll to the calculation/control device 28, such as a computer. Further, the subtracter 26 outputs the difference between the loads on the drive side and the operation side of the rolling roll, that is, the differential load Pdf, to the calculation/control device 28 .

On the other hand, at both ends of the upper backup roll 18 there are provided rolling down devices 30 and 32 with rolling down amount detectors, and the output from the rolling down amount detectors is input manually to a subtractor 34. Therefore, the subtracter 34 outputs the difference in the reduction amount between both ends of the upper backab roll 16, that is, the leveling amount Sdf, to the arithmetic/control device 28.

Thus, the calculation/control device 28 calculates the off-center amount y based on the following equation (21).

a P, +r d 5df y=□ (21) Here, a is a coefficient determined by the dimensions of the rolling mill, and d is a coefficient determined by the conditions of the rolling mill, such as plate width and hardness.

Next, the estimated state value 2 is calculated from the above equation (17), and the leveling change amount U is calculated from the above equation (19), and outputted to the lowering devices 30 and 32.

The control system for the above control is shown in detail in FIG. 5.

In addition, as a leveling amount detection device, instead of determining the difference (differential load) between the driving side and the operating side of the rolling load mentioned above,
It can be determined using an optical sensor or the like.

Effects of the Invention FIG. 6 is a graph showing changes in the off-center amount when the meandering control method according to the present invention is implemented and when it is not implemented. This graph has a width of 1250 mm and a thickness of 2.3 mm.
This is a simulation of the effect of implementing the present invention on a rolled material of This is in good agreement with the situation. On the other hand, when the present invention is implemented, the stability is achieved in a very short time, and the result is clear.

[Brief explanation of the drawing]

1st r! i! J is a control system diagram showing the principle of the meandering control method according to the present invention. FIG. 2 is a control system diagram showing the principle of a conventional meandering control method. FIG. 3 is a schematic diagram showing the relationship between the rolling rolls and the rolled material. FIG. 4 is a schematic configuration diagram of a rolling mill that implements the meandering control method according to the present invention. FIG. 5 is a control system diagram for implementing the meandering control method according to the present invention. FIG. 6 is a graph showing changes in the off-center amount when the meandering control method according to the present invention is implemented and when it is not implemented. [Main reference numbers] 1...Rolled material, 2...Work roll, 10...Rolled material, 12.14...Work roll, 16.
・Upper backup roll, 18..Lower backup roll, 20.22..Rolling load detector, 24.34..Adder, 26..Subtractor, 28..Calculation/control device, 30.3
2. Reduction device

Claims (1)

[Claims] In a rolling mill for rolling steel plates, a method for controlling meandering of a rolled material by controlling the off-center amount of the rolled material by controlling the amount of reduction by controlling the rolling reduction devices on the drive side and operation side of the rolling mill, respectively. , the off-center amount is detected, and the difference in the reduction amount is detected, and the internal variables of the meandering phenomenon are estimated from these two signals, and based on the amount obtained by multiplying the estimated value and the off-center amount by a gain, and calculating the sum thereof. A meandering control method characterized by manipulating the difference in the amount of rolling reduction.