JPH04319014A - Method for automatically controlling plate thickness by optimum monitor - Google Patents

Abstract

PURPOSE:To improve quick responsiveness to plate thickness control by transferring the errors of calculated plate thickness from the final rolling mill to a plate thickness meter in hot rolling and using the representative value of them for correction of a draft position. CONSTITUTION:The plate thickness meter is mounted on the outlet side of a continuous rolling mill, a roll opening drive device to hole an accurate opening at a target draft position and an arithmetic unit for plate thickness errors obtained from a rolling load and a roll opening are prepared respectively, when the plate thickness is controlled by a deviation signal from the plate thickness meter, a calculated plate thickness error from the final rolling mill to the plate thickness meter is transferred and their representative value is used for correcting the draft position. In this way, the responsiveness for plate thickness control can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic plate thickness control method using an optimum monitor.

0002

BACKGROUND OF THE INVENTION In strip rolling using a continuous hot rolling mill, an automatic thickness control system (hereinafter abbreviated as AGC) has traditionally been used to make the thickness distribution of the strip uniform in the longitudinal direction. There is. This AGC detects load fluctuations or sheet thickness fluctuations during rolling using the rolling load or roll reduction position, changes the roll gap amount of the rolling stand through feedforward or feedback using a mathematical model, and changes the exit side sheet thickness. (
For example, Japanese Patent Application Laid-open No. 59-153512).

[0003] Furthermore, in Japanese Patent Application Laid-Open No. 2-165807, when rolling a steel strip using a rolling mill, a rolling device is operated based on a plate thickness deviation signal sent from a plate thickness gauge that measures the thickness of the steel strip. In the plate thickness control method, in which the thickness of the steel strip is feedback-controlled using the feedback control method, when the plate thickness deviation exceeds the preset upper and lower limits, control is performed using the Smith compensation method, and the plate thickness deviation is adjusted between the upper and lower limits. A thickness control method in a steel strip rolling mill has been proposed that performs proportional/integral control when the thickness is between the two.

0004

[Problems to be Solved by the Invention] Conventionally, in plate thickness control using AGC, a dead time t1 is required from the time when the top of the material to be rolled passes through the final rolling mill until the start of control based on plate thickness detection. The plate thickness deviation cannot but become large. As shown in FIG. 5(a), when the integral gain P is large, the operations x1 and x2 for canceling the integral term
occurred, and when the integral gain P was small, a plate thickness deviation Δh remained as shown in (b). The present invention solves these problems and provides an optimal monitor automatic plate thickness control method that significantly improves quick response and improves top plate thickness accuracy.

[0005]

[Means for Solving the Problems] The present invention provides a roll opening drive device that installs a plate thickness gauge on the outlet side of a continuous rolling mill, and maintains the roll opening accurately at a target rolling position, and a rolling load. This device has a calculation device for the plate thickness error calculated from the roll opening and the roll opening degree, and corrects and controls the plate thickness based on the deviation signal from the plate thickness gauge. , and these representative values are used to correct the rolling position.

The present invention will be explained below with reference to the drawings. Figure 1
FIG. 2 is an explanatory diagram of an application example of the present invention. In the figure, 1 is an exit X-ray plate thickness gauge, 2 is a roll opening drive device, 3 is a rolling load meter, 4 is a work roll, 5 is a backup roll, and 6 is a monitor AGC control device. That is, with respect to the monitor AGC control device 6, the plate thickness deviation h(o) and the roll speed v1
, rolling load p, and roll opening degree s are inputted, and a roll opening degree command u is outputted to the roll opening degree driving device 2 .

According to experiments conducted by the present inventors, the dead time t1 included in the control loop from the passing of the top of the material to be rolled through the final rolling mill and the turning on of the load relay of the rolling load cell 3 is 0.25 seconds. there were. The plate thickness deviation Δh at this time was actually measured to be 100 μm, and it took time t2 (10 seconds) for the plate thickness deviation to be resolved by AGC.

The present invention not only performs proportional-integral control, but also transfers and uses calculation errors from the final rolling mill to the plate thickness gauge, thereby greatly improving the responsiveness of the monitor AGC. FIG. 2 shows a flowchart using a shift register. The rolling load p, the roll opening degree s, the roll speed v, and the measured plate thickness h(o) based on xRay are used to input the measured values, and the gauge meter error calculation is performed using equation (1). εh=s+(p/M)−href……(1
) Here, the gauge meter error εh is stored in a shift register, and then shifted by tracking of the register. That is, we obtain equation (2). R(i+1) =R(i) ……………………
(2) Here, R is the register number. i=L/v However, the distance correction value △uk from L:xRay to the final rolling mill is calculated by formula (3), and the integral output is calculated by formula (
4) is calculated.

[0009]

[Math 1]

[0010] Thus, the command value uk is synthesized using equation (5). u(k) =I(k) +△u(k)...(5)

00
11] FIG. 3 is a block diagram of digital control in the present invention. In the figure, 10 is a proportional integral term calculation, 11 is a plate thickness disturbance, 12 is a shift register, 13 is a deviation εh calculated from a gauge meter formula, and 14 is a data memory corresponding to a state corresponding to dead time. There is. Z is the sampling period, and K is the number of times of data, for example, K1 is the data from one time before, and K2 is the data from two times before.

The deviation εh is stored in the shift register 12 as follows:
From t4 to tn corresponding to the dead time, the data is shifted in accordance with the roll speed and made to match the detected plate thickness h. The plate thickness deviation εh is k2, k3
, ki are the correction values. That is, in the present invention, plate thickness deviation information in the dead time area is used.

[0013]

[Example] Hot rolling was carried out in a finishing mill of a hot rolling mill according to the following specifications. Plate thickness: Target plate thickness href = 1.83mm Plate width: B = 1
500mm Mill constant: M=500 ton/mm Plastic constant: Q=2000 ton/mm Plate thickness disturbance (due to skid marks): Load fluctuation value d=50μm (load Pd=25t) Measured value input: p=700t (rolling reduction rate )+25t725ts=1.83
mm v=700mpm xRay Plate thickness deviation: 50μm (dead time 0.25se
c) Gauge meter type error: εh=1.83+(25/500)-1.83=0.0
5. Shift register input and shift (tracking): The above was repeated during the dead time. The shift registers were shifted in the order in which they were input at the same time. Calculation of correction values: h1 = 0.716, k2 = 0.1615, etc. were calculated in advance. △u=+0.176,×0.05+0
．． 1615×0.048+…
=0.01655 Calculation of integral output: k(o) =0.0076 was determined in advance. Initial value I (
o) = 0. I(1) = I(o) +k(o) ×εh(o) =
0.0076×0.05 =0.00038 Command value composition: k=It u(k) =0.0165
5+0.00038=0.01693According to the present invention,
As shown in Fig. 4(b), after dead time t1, t2 =
It was possible to control the deviation to the target within 0.5 seconds. In contrast, the conventional example required t2 = 10 seconds.

[0014]

[Effects of the Invention] The present invention transfers calculated plate thickness errors from the final rolling mill to the plate thickness gauge, and uses these representative values to correct the rolling position. The thickness can be controlled to the target thickness.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is a flowchart of the present invention.

FIG. 3 is a block diagram of the present invention.

FIGS. 4(a) and 4(b) are graphs of plate thickness deviation versus time.

FIGS. 5(a) and 5(b) are graphs of plate thickness deviation versus time.

[Explanation of symbols]

1 Plate thickness gauge 2 Roll opening drive device 3 Rolling load cell 4 Work roll 5 Monitor AGC control device

Claims (1)

[Claims] [Claim 1] A plate thickness gauge is installed on the exit side of the continuous rolling mill,
It has a roll opening drive device that accurately maintains the roll opening at the target rolling position, and a calculation device for the plate thickness error calculated from the rolling load and roll opening. An optimal monitor automatic plate thickness control method, characterized in that the calculated plate thickness error is transferred from the final rolling mill to the plate thickness gauge, and these representative values are used to correct the rolling position.