JPS58163517A - Method and device for controlling sheet thickness in rolling mill - Google Patents

Abstract

PURPOSE:To keep responsiveness constant and to maintain a stable operation and the accuracy of sheet thickness, by obtaining the spring constant of a material to be rolled from the changes of a rolling down force and a roll gap, etc., and changing the gain of a sheet thickness controlling system. CONSTITUTION:The outputs of a pulse genertor 16, a load cell 6, a deviation signal device 8, a roll gas detector 5, etc. are inputted to a command changing device 14. The device 14 calculates a spring constant and also calculates the gain of a servoamplifier 10 by using the spring constant respectively to output a gain changing command to the servo-amplifier 10. Thus the responsiveness is kept constant, and a stable operation and the accuracy of sheet thickness are maintained because the loop gain of the controlling system is kept in a optimum state by changing the gain of the servoamplifier 10 even if the spring constant of sheet is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling the thickness of a plate applied to a rolling mill.

An example of a conventional rolling mill and plate thickness control is shown in Figures 1 and 2 WA.
Explain with reference to. As a hydraulic rolling mill, there is a work roll l and a backup to reinforce this work roll l -
It has a hydraulic cylinder 4 for changing the sail gap in order to control the thickness of the strip 3 rolled between the work mills 1, and a single gap detector 5 attached to the hydraulic cylinder 4. Furthermore, a four-door seventh lever 6 is provided for the backup wheel 2 to detect the rolling blade, and a deviation signal is output from the load cell 6 to generate a deviation signal by subtracting a constant value from the output hitting the rolling blade. connected to device 8;
It is then connected to a coefficient multiplier 9 that multiplies the deviation signal by a constant value. A circuit amplifier 10 is arranged after the coefficient unit 9, and a circuit amplifier 10 is arranged after the coefficient unit 9. The amplifier 10 obtains the O output from the coefficient unit 9, the sum of the deviation between the roll gap current value obtained from the roll gap detector 5, and the target value 11, and changes the sir I current. The scissor controls the opening and closing of the valve 7 by the current of the sergian 7"10, thereby adjusting the amount of oil to the hydraulic cylinder 4.

In an apparatus having this structure, when the target value 11 is set to the required roll gap amount in the absence of the strip 3, the relationship between the work roll l becomes the amount specified by the target value 11. At this time, since there is no strike V-tube 3, the output of the deviation signal device 8 is zero.

In other words, when there is no strip 3, the valve is controlled according to the target value 11, the hydraulic cleaner 4 is moved, and control is performed until the signal from the roll gap detector 5 matches the target value 11. Next, when the strip 3 is placed between the work rolls 1) and the thickness at the exit side of the rolling mill reaches the target thickness, the output of the p-docel 6 is memorized and the deviation signal device 8 is used to determine the target value. is further subtracted from the input output of the load cell 6, and the value is output to the coefficient unit 9.

If the exit plate thickness deviates from the target plate thickness during rolling, the output of the load cell 6 will change and the output from the deviation signal device 8 will no longer be zero], and a difference will occur in the manual power of the amplifier 10, causing the sensor f.
When the electric current R is generated, the valve 7 is opened and the hydraulic cylinder 40 is moved to change the roll gap and control the plate thickness.

FIG. 2 shows the fys of the plate thickness control system based on the configuration shown in FIG. 1. In this block diagram, the same numbers as in FIG. 1 indicate the same parts. In the figure, S.

is the q-le gap setting amount at no load, 8 is the actual roll gap amount at no load, h is the outlet plate thickness, H1i inlet plate thickness, P is the rolling blade, and h is the value when the outlet plate thickness is a predetermined value. reduction blade,
- is the spring constant of the rolling mill, KQ is the spring constant of the cylinder,
f (Rh) is the positive arc property of the material, -1 is the sir? Amplifier 1
0 gain, KV is the flow rate gain of the Ner I valve 7, A is the categorical product of the hydraulic cylinder 4, D is the ulrus operator, and K company's tuner ratio. As a result, the following equation is obtained.

(1) Rolling characteristics of plate P = f (H, h) − (1) (
2) Characteristics of rolling mill h = 8 10P/KM ・” (2
) (3) Characteristics of rolling down device and plate thickness control system ~ 5 P 15 (-P+Po)+o-8) -+ -=8AD
K.

...(3) When the inlet plate thickness is horse and the no-load roll gap is 80, the rolling blade is Po and the outlet plate thickness is.

Then, outside the wound (tl, (21, (3)) becomes as follows.

Also, JP=P−Po ΔH=H-hiki Δh=hh.

When ΔS″β−8o, the following equation is obtained.

(1) From equation (4), jp = KlB (ΔH−jh) −
...(7) (2) From equations (5), (3) From equations (6), As a result, Zino P and ΔS are eliminated according to equations (7), (8), and (9).

Here, the spring constant of the K-plate is the reciprocal of the coefficient of D in the denominator of the above equation using loop dyne.

As can be seen from the formula, this loop die y[ depends on the flow rate gain of the inner valve 7, the plate spring constant 4, the rolling mill constant 4, the cylinder spring constant 4, and the chain cylinder k. ), which governs the stability and responsiveness of the control system.

In order to improve the stability and responsiveness of the conventional system, the circuit adjusts the loop 1 dyne K by changing the gain control of the amplifier 7' IO in response to changes in the chain-inder ratio, and the circuit adjusts the gain control of the valve 7'
In response to changes in the flow rate gain KV, A method of adjusting the loop gain K by changing the gain of the amplifier 10 has been proposed. It is also possible to correct the loop gain KO by setting the spring constant of the rolling mill to 4 and the spring constant of the cylinder to 4.

An object of the present invention is to provide a plate thickness control method and device that optimizes the loop 1 dyne by changing the gain of the amplifier in response to changes in the plate O spring constant 4.

In order to achieve this object, the present invention (1) determines the spring constant of the rolled material from changes in rolling force, roll gap, and plate thickness during rolling and the spring constant of the rolling mill measured in advance; It is characterized by changing the gain of the plate thickness control system depending on the value of the spring constant of the rolled material, (2) Calculating the spring constant of the rolled material from the output of a load cell for detecting rolling force and a detector for roll gap. and a device that changes the control gain of the jIl plate thickness control system according to the spring constant of the rolled material.

The present invention will now be described in detail with reference to FIG. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals. 1
2 is the work roll, 2 is the tool 10-tool, reinforcing pack far, 4 is the hydraulic cylinder, 5 is the roll gap detector, 6 is the load cell, and 8 is the output from the load cell] A deviation signal for subtracting the target value 9 is a coefficient unit, 10 is a sensor amplifier, 11 is a target plate thickness value, and 7 is a valve. Of these, the sirian 110 has a function of adjusting the dyne using a signal from a change command device, which will be described later.

A pulse generator 16 is connected to the electric motor 15 that drives the work roll 1.
The output of is connected to the change command device 1'4. In addition to the output of the pulse generator 16, the change command device 14 receives the output of the load cell 6, the output of the deviation signal device 8, the output of the roll wear detector S, etc. Then, this change command device x+i performs respective calculations for the sir amplifier 100 dyne Kh using 3 and 4 for the spring constant of the plate, and outputs a gain change command to the sir I amplifier 10. Another input to this change command device 14 is the plate thickness value 1.
7 and chain-ender rate 18.

The calculation of the spring constant of the plate in this change command device 14 will be explained. One formula is given as a calculation formula for the spring constant of the plate, 4'.

1 (-10-) no p = j3 + jsM + no S6
··· uK, KM To apply this formula al), the spring constant of the rolling machine is determined in advance as a function of the plate width and the rolling blade.

That is, it is determined from the plate width value of 17 and the output of 60 in -doce. 8) 1 is the oil film thickness of the bearing of the take-up four reel 2, which is a function of the rolling blade and reel rotation speed.
It can be determined from the rotational speed based on the output of the f-lux generator 56 and the output of the four-wheel drive generator 56. Although it is impossible to directly calculate the roll eccentricity jS of the roll 2, this Se is a periodic function of the rotation angle of the backup roll 2, and the output ΔP of the deviation signal device 8.

- Difference ΔS between the output of the gap detector 5 and the set value 11
, oil film thickness Δ8H'%/f Lus Generator 160 output Periodically, a plurality of points are memorized during one rotation of the backup roll 2, and can be removed by taking the average. As a result of the above, k * jp, *s, Ja
n, js・ are specified, and the average value JP, js
, Δ axis and -! 1 and ΔS@WO can be substituted into the aD formula to obtain the spring constant 4 of the plate.

Next, when calculating the gain KAO of the energy amplifier lO, apply the Hiro set and calculate the spring constant of the round plate 4 according to the above.
The spring constant K of the cylinder as a function of the oil column determined from the spring constant of the rolling mill and the chain cylinder ratio 3g input from the outside, and the output S of the a-le gap detector sO. This occurs in the conventional example where the servo changes the dyne of the amplifier 10 in response to a change in the flow rate gain of the valve 7, that is, when the hydraulic cylinder 4 rises and falls, respectively. - In other words, the change in the differential pressure of the I valve 7 is the reduction force, which is obtained from the load cell 6, and is stored in advance as 9 ru and 1 dyne, and the cross-sectional area of the cylinder 40 as the servo? The guim of the amplifier lO is found.

After the above-mentioned calculations are performed by the change command device 14, the signal yKA is inputted to the amplifier IO to change its gain.

According to the above-described principles and embodiments, even if the spring constant of the plate changes, the loop gain of the control system can be maintained optimally by changing the rate of change, so that self-stable operation and plate thickness accuracy can be maintained with constant response.

[Brief explanation of the drawing]

1 and 2 are simplified block diagrams and diagrams of rounding in conventional plate thickness control, and FIG. 311 is a simplified block diagram of an apparatus for explaining the plate thickness control method according to the present invention. In the drawing, reference numeral 5 is a Rollseyep detector, 8 is a deviation signal device, 10 is a sensor amplifier, and 14 is a change command device. Patent applicant: Mitsubishi Heavy Industries, Ltd., sub-agent Patent attorney: Shibu Mitsuishi (and 1 other person) Figure 1 Figure 2

Claims (2)

[Claims] (1) Changes in rolling force and roll gap during rolling,
The spring constant of the rolled material is determined from the plate thickness change and the spring constant of the rolling mill in advance, and the plate thickness control system Or-in is changed according to the value of the spring constant of the rolled material. A method for controlling plate thickness in a rolling mill. (2) A device that calculates the spring constant of the rolled material from the outputs of a load cell for detecting rolling force and a detector for the roll gap, and a control gain of the plate thickness control system that changes according to the spring constant of the rolled material. A plate thickness control device comprising: