JPS62104614A - Control method for rolling plate thickness - Google Patents

Abstract

PURPOSE:To improve the productivity of the plate with high accuracy by estimating the plate speed variation at the inlet side from the plate thickness variation at the inlet side and by controlling the plate feeding speed so as to constrain the fluctuation in the tension at the inlet side to be caused by the plate speed variation thereof. CONSTITUTION:The plate thickness at the inlet side, if varies, is detected by a plate thickness gage 3, the signal thereof is transmitted to a control device 4 and the device 4 transmits a signal to a servo valve 5, transmitting the signal to the control device 10 of the inlet side tension reel 9 as well. The generation of the fluctuation in the inlet side tension is then controlled by controlling the inlet side plate feeding speed of the tension reel 9 by changing the armature current of the DC motor 11 for reel.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rolled plate thickness control method for automatically controlling the thickness of a rolled plate to a predetermined value in rolling a plate such as a copper strip. It is related to.

(Prior art) Conventionally, the rolling mill's rolling machine had a slow rolling speed.
The control cycle had to be long, and plate tension fluctuations did not pose a problem in plate thickness control.

However, in recent years, with the spread of hydraulic drafting, the reduction speed has increased, and it is no longer possible to further improve the accuracy of automatic plate thickness control unless changes in plate tension, which were not a problem in the past, are taken into account.

Japanese Patent Publication No. Sho Go-21008 shows a method to remove the influence of tension fluctuations by sampling the exit steel strip after the tension fluctuations have stabilized and starting the next rolling process. Since plate thickness control is not performed while tension fluctuations are stabilized, plate thickness deviations that change in a relatively short period cannot be removed.

FIG. 2 shows how a plate 1 is rolled by work rolls 2 in a rolling mill. When the law of constant volumetric flow rate is applied to the rolling phenomenon, the equation (1,) is obtained.

Vl hl = V2 h2 ・・・・・・・・・
...... (1) However, v and +hl indicate the plate speed and plate thickness on the inlet side, and v2+h2 indicate the plate speed and plate thickness on the outlet side.

Solving this for vl yields equation (2).

The minute change Δv1 in vl is expressed by equation (3) by linear approximation.

However, Δv2, Δh2, and Δhl respectively indicate minute changes in the plate speed, plate thickness, and inlet side plate thickness on the exit side.Here, the variation Δv2 in the plate thickness on the outlet side makes the plate thickness on the outlet side constant. Control I] Ding',・Yu,'T? is small, so by finding it and substituting it into equation (3), we get Δh1 ・・・・・・・・・・・・・・・(4
) By rearranging equation (4) using equation (2), equation (5) is obtained.

This formula represents the minute change in the entrance plate speed when the entrance plate thickness and exit plate thickness change minutely.

The minute changes in the preliminary grinding wheel and entry tension are expressed as ΔS and Δ, respectively.
If it is set as T, then the minute change Δh2 in the thickness of the exit side plate is:
Using linear approximation, the equation (6) is generally expressed as % where α, β, and γ are the influence coefficients of the entrance plate thickness, rolling reduction, and tension, respectively. Furthermore, the tension reel and plate on the entry side can be seen as a vibration system made up of weights and springs. FIG. 1 shows this and equations (5) and (6) collectively expressed as a transfer function. Here, k is the spring constant of the board on the entry side, 'NZ is the speed 1 at which the reel sends out the board.
m is the moment of inertia of the inlet reel, motor, etc. divided by the square of the inlet coil radius, and S is the Laplace operator. Further, A and B are constants.

(Problems to be Solved by the Invention) In FIG. 1, when the inlet plate thickness ■ changes, the outlet plate thickness ■ tends to change via the inlet plate thickness influence coefficient α.
The conventional plate thickness control is feed forward control, which determines the amount of reduction (■) such that ■+■−〇 so that the exit side plate thickness does not change. However, here the exit side board thickness■
Another path to change -'0→\suppression)→(hr→
■Exists. In other words, when the inlet plate thickness changes, the inlet plate velocity v1 changes due to the constant volumetric flow rate law.

The DC motor for the tensile reel on the entry side has constant torque control, but because it has a large moment of inertia, it cannot follow the increase in the speed of the entry plate, and only changes in the speed of the entry plate occur, and the output plate It ( Change ψ.

The influence of this +) on the fluctuation in the frequency changes the frequency characteristic of plate thickness control.In other words, if the change in plate thickness on the inlet side is gradual, the change in plate speed on the inlet side will be gradual. can be followed even with constant torque control, but if the change in plate thickness on the inlet side is fast, the tension/reel cannot be followed, so even if it has a response characteristic of, for example, a rolling down device 6 or an IDH2, 0.I Hz. The result is that only the following plate thickness variations are sufficiently removed.

The purpose of the present invention is to suppress the occurrence of changes in the speed of the inlet side plate and to control the outlet side plate thickness to be constant even when the inlet side plate thickness changes rapidly.

(Means for Solving Problems and Problems) The present invention predicts an increase in board speed on the entry side from a change in board thickness on the entry side, and adjusts the board feeding speed so as to suppress fluctuations in tension on the entry side caused by this change in board speed. By controlling this, the entry tension can be kept constant and the characteristics in a relatively high frequency range during plate thickness control can be improved.

In the following, rolling of a steel strip using a reversible rolling mill will be described.

An application example of the present invention will be explained with reference to the drawings.

FIG. 3 shows the steel strip 1 being rolled from left to right. Changes in the entrance side plate thickness are detected by the plate thickness gauge 3 and transmitted to the control device 4. The change in the exit side plate thickness is detected by the plate thickness gauge 6 and similarly transmitted to the control device jδ4.

Here, if the plate thickness on the entry side changes, this is plate thickness work 13
is detected, the signal is processed by the control device 4,
When that part of the plate approaches the work roll 2, a signal is sent to the servo valve 5, and the reduction cylinder 7 changes the coal gap. The amount of movement of the reduction cylinder 7 is constantly detected by a reduction detector 8, so that the reduction is made by the required amount, and whether or not the exit side plate thickness is controlled is detected by a plate thickness meter 6. Ru.

Here, in the present invention, when the entrance side plate thickness changes, the control device 4 sends a signal to the servo valve 5 as before, and also sends a signal to the control device 10 of the entrance side tension reel 9, so that the reel DC motor 11 il) By changing the seed current and controlling the speed at which the tension reel 9 feeds out the inlet side plate, the occurrence of changes in the inlet side plate speed is suppressed.

(Function) To explain using the m1 diagram, when the inlet plate thickness changes by Δh1, as shown within the dotted line in the figure, due to foot forward control, the minute change in the outlet plate thickness that occurs in the path (■) is caused by the rolling down device. If the roll gear control layer (■) is an appropriate value, the change in (■) can be ignored because it is almost canceled out by this (■). In this case, the minute change Δv1 in the entrance plate feed caused by the path (■) is expressed by equation (7).

Therefore, if the board feeding speed v2 on the entry side is changed by the same amount as Δv1 so as to cancel the speed increase ΔV on the entry side, the tension fluctuation on the entry side can be suppressed as follows. In the case of a rolling mill with a tension reel on the entry side, in order to change the plate feed speed, add '+1!' to the armature of the reel driving DC motor. The flow must be done as shown in equation (8).

I=(Tension setting゛Ni flow) 1ΔI ・・・・・・・・・
(8) Here, ΔI that makes the tension fluctuation on the entry side zero is 6.

As you can see from Figure 1, ΔVR=ΔV】 ・・・・・・・・・・・・・・・ (
9) The minute change in the entrance plate feed speed Δv8 should be determined as follows: ΔVR; @ B salary Δt (
10) Since m kai S , by substituting equations (7) and (10) into equation (9) and finding ΔI, equation (11) is obtained.

It is obtained by this equation (11). By adding tiIft, the value Δ■ to the tension setting TL flow value and applying it to the electric motor 11, a desired speed change can be applied to the inlet tension reel.

Note that the above explanation is based on the roll gear control i using the rolling down device.
We have shown when n is an appropriate value, but when it is not an appropriate value,
It can be easily imagined that tension fluctuations can be suppressed by predicting changes in plate feed on the entrance side of the rolling mill using FIG. 1 based on the control amount of reduction and changes in plate thickness on the entrance side.

Moreover, although the above description has shown application to a reversible rolling mill, it is also applicable to automatic plate thickness control of a tandem rolling mill.

(Effects of the Invention) As explained above, according to the present invention, the high frequency characteristic of plate thickness control, which cannot be solved no matter how fast the rolling device is increased, is the cause of the problem. Since the improvement is achieved by eliminating tension changes, high-speed rolling can eliminate fine changes in plate thickness, which until now had no other option than lowering the rolling speed. Therefore, it is possible to improve the productivity of plates that require high precision.

[Brief explanation of drawings]

FIG. 1 is a blow diagram showing the flow of signals for explaining the rolled plate thickness control method according to the present invention. FIG. 2 shows the volume t and quantity rules in rolling phenomena, and FIG. 3 is a system diagram of an automatic plate thickness control device to which the rolled plate thickness control method according to the present invention is applied. ■...Steel strip, 2...Work roll, 3.6...Plate thickness gauge, 4...Control device, 5...Servo/< loop, 7
...Reduction cylinder, 8...Reduction amount detector, 9...
Tension reel 10... Reel control device, 11.
・Directly fixed motive for reel.

Claims (1)

[Claims] A method for controlling plate thickness in a rolling mill, comprising predicting a change in plate speed on the entering side based on a change in plate thickness on the entering side, and controlling plate feeding speed so as to suppress fluctuations in tension on the entering side caused by the change in plate speed.