JPS61162220A - Plate thickness automatic control method - Google Patents

Abstract

PURPOSE:To perform the plate thickness control with high accuracy and high stability by controlling a roll opening adjusting device, etc. with using the influence coefficient of the deviation in roll openings against the plate thickness deviation at the outlet side calculated from the signal transmitted from a plate thickness gate and roll opening detector. CONSTITUTION:The device is composed of the X ray plate thickness gage 2 to measure the plate thickness of a strip 1, various rolls 3, 4, a roll opening detector 5, arithmetic unit 8, roll opening adjusting device 9 and rolling reduction screw driving device 7, etc. The plate thickness deviation at the outlet side and roll opening deviation are taken up to an arithmetic unit 8 from the thickness gage 2 of stand outlet side. The opening command value for making the plate thickness deviation at the outlet side in zero from the arithmetic equation is outputted to the opening adjusting device 9. The opening adjusting device 9 takes up the opening deviation and controls the roll opening so as to make the command value = deviation via the rolling reduction screw driving device 7. The plate thickness automatic control of high accuracy and high stability can be thus performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to automatic sheet thickness control (AG) used in cold rolling mills.
C) Regarding the method.

(Conventional technology and problems) In recent years, users' demands for quality in the steel industry have become more or less obscure. On the other hand, since the oil crisis in recent years, energy conservation has been promoted and various measures have been taken, but the GORERA glue I measures (low temperature heating, increased bar thickness, etc.) tend to deteriorate strip quality. be.

In the cold rolling process, the shape and thickness of the strip product are determined, so conventionally the height of the automatic sheet control device is 1.8i.
Improvements in functionality and high response have been made. FIG. 3 shows an example of an automatic plate thickness control device, in which 1 is an IJ knob, and 2 is an X-ray plate thickness meter for measuring the thickness of the strip. 10 is a rolling stand, 3 is its warp +:r-roll, 4 is a backup roll, 5 is a roll opening degree detector, 6 is an automatic double plate thickness control (AGC) device, and 7 is a rolling screw drive device It is. As is well known, there are two types of automatic plate thickness control (AGC) systems: the Bisla method and the monitor method.
The rolling load P when the plate thickness is the desired value is determined by the roll gap S
In a tandem mill, the load is calculated from the mill constant M, and in a tandem mill, the rolling load is locked on when the final stage exit plate thickness reaches a predetermined value. ), during rolling, the rolling load is measured and the roll gap is corrected according to the deviation from the set value, so that the thickness of the sheet at the exit side remains constant. This Bisla method does not calculate the actual plate thickness δIl+, so there is no need for a plate thickness gauge, and it also has the advantage of not introducing a delay time corresponding to the strip running time from the roll to the plate thickness gauge to detect the plate thickness. Since the plate thickness is determined by calculation, it is difficult to respond to changes in the values of the parameters used and tends to deviate from the actual value. In this regard, in the monitor method, the plate thickness is actually measured and the pressure F is controlled according to the deviation from the desired value to achieve the desired outlet plate thickness, so although there is a gap where a plate thickness of 81 is required, There is no problem of deviation from the actual value. FIG. 3 shows a monitor system in which the AGC device 6 takes in the actual plate thickness at the exit side of the stand from the plate thickness gauge 2, calculates the deviation from the desired value (pj), and uses the deviation to determine the thickness of the plate via the screw drive unit 7. The ib control of the LJ-small gap is carried out using this method.The transfer function diagram of the mechanical system of the AC and C systems is shown in FIG.

In Fig. 4, 11 indicates the transfer function of the reduction system (reduction screw drive system;
13 indicates the transfer function of the stand 10. The rolling control system generates a roll gap correction amount ΔS in response to a control signal SS from an AGC device 6 or the like, and this changes the exit side plate thickness, the degree of which is represented by a block 12. That is, M/ to ΔS
The value multiplied by (M+Q) is the outlet side plate thickness deviation -Δh1. Output 1ull plate thickness deviation occurs even if the input side plate thickness changes, and the amount due to this Δh2 becomes hl(i - Q/ (M + Q) if the input side plate thickness deviation is Δt(i). Therefore, the overall output The side plate thickness deviation Δh is Δ 11+−Δ 112−Δ hl. From this formula (1), to make the exit side plate thickness deviation Δh zero, set the right side of the il1 formula to O, that is, ΔS=Q・Δ!I
i/M... (2) should be used. Calculation of ΔS using equation (2) requires knowing the mill stiffness constant M and the strip average deformation resistance Q. The former changes due to roll changes, etc., and the rear t changes due to skin 1' marks, etc., so it is necessary to know the mill stiffness constant M and strip average deformation resistance Q. values are not easily obtained.

Therefore, it is common practice to set these values to constant values, but of course this introduces errors.

In recent years, in order to reduce the performance deterioration of the control device due to changes in the strip average deformation resistance at the top, bottom, gap, and mark portions of the slip, the average strip deformation resistance has been estimated in recent years, and the estimated A method has been proposed to adaptively modify the equivalent gain of the controller based on the results. Although this method is effective, it is necessary to install strip thickness gauges at the front and rear of the cold rolling mill.
If the strip plate thickness 1 is present only on the 18th surface of the cold rolling jl as shown in the figure, the above correction method cannot be adopted. A rolling mill having a plate thickness of 81 only on the rear surface of the rolling mill is found in stand-alone rolling mills or first-stage rolling mills of tandem mills.

The present invention has been made to improve these points, and aims to provide a high-precision automatic plate thickness control device that can be applied even when the strip thickness is 81 only at the rear of the cold rolling mill. .

[Means for solving problems]

The present invention provides an automatic plate thickness control method for a cold rolling mill that is equipped with a roll opening adjustment device, a roll opening detector, and a plate thickness gauge on the exit side of the rolling machine. The signal from the detector is taken in, and the influence coefficient of the roll opening deviation on the outlet side plate thickness deviation and the plate thickness disturbance are calculated using an arithmetic formula, and the roll opening that makes the outlet side plate thickness deviation zero is calculated from the calculated influence coefficient and plate thickness disturbance. A rolling mill equipped with a roll opening adjustment device, a roll opening detector, and a plate thickness gauge on the exit side of the rolling mill. In the automatic plate thickness control method, the plate thicknesses 81 and 1.
The signal from the J-ru opening rolling device is taken in, and the influence coefficient of the roll opening deviation on the exit side plate thickness deviation is calculated using the f4 formula. This system is characterized by adaptively correcting the loop gain of the automatic plate thickness control system by adjusting the rolling reduction including the following.

〔Example〕

When the outlet side, inlet side plate thickness deviation, and roll opening degree deviation of the above +1j equation are expressed as a time function (focusing on ΔS and ΔHi), the following equation (3) is obtained. Here, I is a time parameter.

Since M and Q in this equation (3) change from time to time, it is changed to equation (4).

Δh (1) - ΔH (1) -a (I) Δ5 (1) 10 δ
(1)=・・・-(41ΔI+(+)−ΔHi(1)・
Q/(M〇)a (1)-M/ (M+Q) δ (1): Why 1-Noise This equation (4) expresses the time-varying M/ (M+Q) by Δ
Influence coefficient a (1) of Δ5(1) on h (1)
This is an attempt to determine this using the Kalmar filter method. White (・noise δ white) is Δ5 (
1), etc., and has the property of ``E(δ(+) δ(J))-σ2δ1'', and in this case, E(δ(■))-〇. do. Here, E is the uniform average, σ is the standard deviation, and J is the time distant from I. Regarding the parameters a(I) and ΔI+(1), equation (5) is assumed.

These f41. The following equation (6) can be obtained from the i51 equation (this derivation process is quite complicated, so only the results are shown).

(A h(1) -A r((1-'1) +
A S ([) 2゛ (1-1)) (6) That is, if you know ΔS (1) and Δh (1), you can calculate the entry side plate thickness deviation ΔH (1) and the influence coefficient a (1 ) can be obtained, and once these are obtained, the exit side plate thickness deviation Δh (
The roll opening command value Δ5(1)r for making 1) zero is determined as shown in the following formula.

ΔS(+)r−ΔI((1)/a(1)
・=・f? FIG. 1 shows an AGC system that performs the following control. In this figure, the same parts as in FIG. 3 are given the same reference numerals, and 8 is a calculation device (corresponding to the AGC device 6 in FIG. 3). N
) and the roll opening deviation ΔS from the roll opening detector 5.
Take in (1) and calculate ΔH(1) using equation (6).
and a (1), and further calculates equation (7) to set the opening command value Δ5(1) to 0.
) outputs r. Reference numeral 9 denotes a roll opening degree adjusting device, which takes in the command value Δ5(1)r and the roll opening degree deviation ΔS (1), and converts it via the reduction screw drive device 7 to ΔS (1) =
The roll opening degree is controlled so that Δ5(1)r.

A, which is conventionally performed using the influence coefficient a (1)
Figure 2 shows the configuration of the GC system. Block 16, addition point, and plate thickness disturbance ΔI ((1) indicates the rolling mill 10, and the input signal of block 16 is the roll opening deviation ΔS
(1). Block 14 shows the transfer function of the roll opening adjustment device 9, block 15 shows the transfer function of the reduction screw drive device 7, Δh ref is the target value for changing the thickness of the outlet side of the stand 10, and Δh(1) is the deviation of the thickness of the outlet side. is the actual measured value, and Δh(1) is negatively fed back to the roll opening adjustment device 9,
The output of said device 9 operates the reduction screw drive device 7.
However, a roll opening deviation Δ5(1) is produced.

In such an automatic plate thickness control system, if the influence coefficient a (1)=M/<M→Q) is estimated as shown in −F, then the gain G of the adjustment device 9 and the influence coefficient a(1) Tono G
If the gain G is adjusted so that -a(1) is constant, the loop gain of this automatic plate thickness system becomes constant, and stability and/or coordination can be improved. In this case, only a (1) of Δ11 (1), a (1) calculated by the arithmetic unit △ △ Δ 8 is used, but since the only change is G in Fig. 2, the existing automatic plate thickness control system can be used. There is almost no need to modify (just make the gain of the amplifier of adjustment device 9 variable)
There is an advantage. Note that the gain adjustment is done using the register and I)
Using a /A converter and an amplifier whose gain is controlled by the analog output of the converter, it is easy to input the required value into the register using a calculator. For this gain adjustment, the method in Figure 1 is Δ5(1)r in Figure 2.
and Δ5(1) is input into block 15, and block 1
4 and the W operator of (Δhref−Δh(+)) are removed,
Some modifications will be required. However, in Fig. 1, the plate thickness disturbance ΔH(+) is calculated by ΔS (1), which cancels it, and the reduction control is immediately performed, so the exit side plate thickness does not change over time (△h(1) = 0), but in Figure 2, Δh(1) is generated by Δ11(1), which is then negatively fed back and corrected to 0, so Δh(1)iJ Let's make a change that first rises and then disappears.

(Effects of the Invention) As explained above, in the present invention, the influence coefficient of the roll opening adjustment on the exit side plate thickness is calculated by the thickness disturbance (inlet side plate thickness deviation) using the actually measured exit side plate thickness deviation and the same roll opening deviation. The required roll opening correction amount is calculated using the formula W along with the exit side Fj and WJ deviation), and the required roll opening correction amount is calculated using the 11y correct amount to adjust the opening of one coil, or the influence calculated above The loop gain of the automatic plate thickness control system due to rolling reduction is adaptively controlled to a constant value by the coefficient, so automatic plate thickness control with high precision and high stability can be achieved despite fluctuations in the mill stiffness coefficient and slip average deformation resistance. In addition, since the signals to be captured are only the exit side plate thickness and roll opening degree, the input side plate 7 words and 1
It can also be applied to rolling mills that do not have

[Brief explanation of drawings]

1 and ff12 are explanatory diagrams and block diagrams for explaining the present invention, and FIGS. 3 and 4 are explanatory diagrams and block diagrams for a conventional AGC system. In the drawing, 9 is a roll opening adjustment device, 5 is a roll opening detector, 2 is a plate thickness 81, and Δ5(1)' is a roll opening command value.

Claims (2)

[Claims] (1) Equipped with a roll opening adjustment device and a roll opening detector,
In addition, in an automatic plate thickness control method for a cold rolling mill equipped with a plate thickness gauge on the exit side of the rolling mill, signals from the plate thickness gauge and roll opening detector are taken in, and a calculation formula is used to determine the roll opening deviation of the exit side plate. Calculate the influence coefficient and plate thickness disturbance on the thickness deviation, determine the roll opening command value that makes the exit side plate thickness deviation zero from the calculated influence coefficient and plate thickness disturbance, and give the command value to the roll opening adjustment device. An automatic plate thickness control method characterized by: (2) Equipped with a roll opening adjustment device and a roll opening detector,
In addition, in an automatic plate thickness control method for a cold rolling mill equipped with a plate thickness gauge on the exit side of the rolling mill, signals from the plate thickness gauge and roll opening detector are taken in, and a calculation formula is used to determine the roll opening deviation of the exit side plate. An automatic plate thickness control method characterized by calculating an influence coefficient on thickness deviation and adaptively correcting the loop gain of an automatic plate thickness control system by rolling reduction adjustment including a roll opening adjustment device and a rolling mill using the calculated influence coefficient. .