JPH06114426A - Rolling down device for rolling mill - Google Patents

Abstract

PURPOSE:To control a position stably and with high accuracy irrespective of elongation of stroke of a hydraulic cylinder. CONSTITUTION:A position setting equipment 2 gives a position command of a hydraulic cylinder 10 through a signal from an automatic sheet thickness controller 1 to a subtraction circuit 3 as a target value. The position of the piston of the hydraulic cylinder 10 is detected by the position detector 11 and given to the subtraction circuit 3 as an oil pillar S. A motion control signal E is given to a servo amplifier 8 through a controller 4 having a transfer function K and an oil pillar compensatory circuit 7 having a compensatory coefficient of alpha. A servo valve 9 is actuated by an output from the servo amplifier 9 to displace the hydraulic cylinder 10. The compensatory coefficient alpha in the hydraulic pillar compensatory circuit 7 is generated by a compensatory value generating circuit 6 responding to the oil pillar S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic rolling apparatus for a rolling mill for rolling a thin sheet hot or cold.

[0002]

2. Description of the Related Art Conventionally, in hot and cold rolling mills for thick and thin plates, hydraulic type rolling-down devices are superior in position control accuracy and responsiveness and have a simple structure. It is the mainstream. A prior art relating to a hydraulic type pressure reducing device is disclosed in, for example, Japanese Patent Publication No. 53-12265.
Publication, Japanese Patent Publication No. 60-20089 and Japanese Patent Publication No. 3
No. 80561, for example.

In recent rolling mills, a mill capable of switching between large and small diameter rolls has been proposed in order to enable the production of a wide variety of products. In order to enable switching between large and small diameter rolls, the stroke length of the hydraulic cylinder must exceed 100 mm.
Also, even when not switching between large and small diameter rolls,
A stroke length may differ by 100 mm or more between a new roll and a roll subjected to repeated polishing.

[0004]

In conventional hydraulic pressure rolling mills, there are few rolling cylinders having long stroke lengths. If the stroke length is long, the oil column, which is the height of the hydraulic oil in the cylinder, rises, and the air bubbles mixed in the hydraulic oil contract, so the apparent volume of the hydraulic oil decreases and the cylinder response increases. The phenomenon of slowing down occurs. The difference in response speed due to the difference in stroke length makes stable and highly accurate control over a wide range of stroke lengths difficult.

In the prior art disclosed in Japanese Patent Publication No. 53-12265 and Japanese Patent Publication No. 60-20089, the control is compensated based on the pressure of the hydraulic oil.
In the prior art disclosed in Japanese Examined Patent Publication No. 3-80561, compensation is performed based on the control speed. In these prior arts, it is expected that stable and high-precision control can be performed on an oil column in a narrow range, but it is difficult to perform stable and high-precision control over a wide range of stroke length.

An object of the present invention is to provide a hydraulic rolling reduction device for a rolling mill capable of preventing the position control performance from varying depending on the stroke length of the rolling down means.

[0007]

According to the present invention, in order to displace the work roll by the rolling-down means using the cylinder, the position of the piston of the cylinder is used as a control amount so that the difference from a preset target value becomes small. In a hydraulic pressure reduction device for a rolling mill, which is feedback-controlled to, a gain compensating means for setting the proportional gain in the feedback control to be larger as the supply amount of hydraulic oil to the cylinder is larger, that is, the oil column is higher. Is a hydraulic pressure reducing device for a rolling mill.

[0008]

According to the present invention, the hydraulic pressure reducing device for a rolling mill displaces the work roll by the pressure reducing means using the cylinder. This displacement is controlled by the position of the cylinder piston,
It is performed so that the difference from the preset target value becomes small. In this feedback control, the gain compensating means is set so that the proportional gain increases as the amount of hydraulic oil supplied to the cylinder increases. As the amount of hydraulic oil supplied to the cylinder increases, the response delay due to bubbles in the hydraulic oil increases, but the proportional gain in feedback control also increases, so compensate for the response delay due to a longer stroke. You can

[0009]

1 is a block diagram showing a control system of a hydraulic pressure reducing device for a rolling mill according to an embodiment of the present invention. Into the automatic strip thickness control device (abbreviation “AGC”) 1, the outgoing strip thickness rolled by the rolling mill and the rolling load are input.
The automatic plate thickness control device responds to the delivery side plate thickness, rolling load, etc., and gives the position setting device 2 a signal for designating the position of the piston of the cylinder in order to displace the work roll. The position setting device 2 gives a position command representing the position set by the automatic plate thickness control device 1 to the subtraction circuit 3 as a target value. From the subtraction circuit 3, a control operation signal E representing the difference between the position command and the control amount is given to the controller 4. The controller 4 has a characteristic represented by the transfer function K and outputs a product KE of the control operation signal E and the transfer function K. This output is compensated by the compensation coefficient α from the gain compensation means 5.

FIG. 2 shows the relationship between the value of the compensation coefficient α generated from the compensation value generating circuit 6 in the gain compensating means 5 and the value of the oil column at that time. The compensation coefficient α is equal to 1.0 when the oil column is 0 to So. When the oil column increases from So to Sm, the compensation coefficient α also increases from 1.0 to αm. Figure 1
The illustrated compensation value generation circuit 6 operates as a function generator that generates a function as shown in FIG. Oil column compensation circuit 7
Derives the product of α generated by the compensation value generation circuit 6 and the output generated by the controller 4 as a hydraulic pressure compensation value.

The servo amplifier 8 controls the servo valve 9 operated by hydraulic pressure in response to the hydraulic pressure compensation value. The hydraulic oil is supplied to the hydraulic cylinder 10 or returned from the hydraulic cylinder 10 by the operation of the servo valve 9. The movement of the hydraulic oil with respect to the hydraulic cylinder 10 causes a change in the piston position within the cylinder. The piston position is detected by the position detector 11, and the signal S representing the position is derived. The signal S representing the position is given to the compensation value generation circuit 6 and the subtraction circuit 3. In the compensation value generation circuit 6, the output S from the position detector 11 is used as an oil column to obtain a compensation coefficient α and apply it to the oil column compensation circuit 7. In the subtraction circuit 3, the output S from the position detector 11 is used as a control amount to obtain a control deviation with respect to a position command that is a target value in the subtraction circuit 3 and output as a control operation signal E.

FIG. 3 shows a schematic mechanical structure of a rolling mill using the embodiment shown in FIG. Portions corresponding to the electrical configuration shown in FIG. 1 are designated by the same reference numerals. Hydraulic cylinder 1
0 has an oil column length S corresponding to the piston position. The position of the piston of the hydraulic cylinder 10 is detected by the position detector 11. Rolled material 12 rolled by a rolling mill 12
The outgoing side plate thickness t of is detected by the plate thickness detector 13.
The load cell 14 detects a rolling load.

Each mechanism is housed in the rolling mill frame 15. The load cell 14 is attached to the upper part of the frame 15, and the hydraulic cylinder 10 is installed to the lower part. Between the load cell 14 and the hydraulic cylinder 10, large-diameter reinforcing rolls 16 and 17, intermediate rolls 18 and 19, and small-diameter work rolls 20 and 21 are provided. Work rolls 20, 21
Preferably has a small diameter in order to increase the rolling reduction of the rolled material 12. Since the rigidity is insufficient when the work rolls 20 and 21 have a small diameter, they are backed up by the intermediate rolls 18 and 19 and the reinforcing rolls 16 and 17.

FIG. 4 shows response characteristics with the oil column S in the hydraulic cylinder 10 shown in FIG. 3 as a parameter. For example, when the oil column S is 40 mm and the piston in the hydraulic cylinder 10 is displaced by +50 μm, the response characteristic is as shown by the solid line. When the oil column S is 60 mm,
Even if it is displaced by 50 μm, the response characteristic is as shown by the chain double-dashed line. As the oil column S becomes larger, the response speed becomes slower. According to the present embodiment, the delay of the response speed due to the operation of the oil column S is generated by the compensation value generation circuit 6 and the oil column compensation circuit 7 is provided with the compensation coefficient α represented as a function as shown in FIG. By compensating for the proportional gain of the feedback control, stable and highly accurate control is possible even if the hydraulic cylinder 10 is delayed in operation.

FIG. 5 is a block diagram showing a control system of a hydraulic pressure reducing device according to another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1, and the corresponding parts are designated by the same reference numerals. It should be noted that the compensation value generation circuit 6 is given a position command as a target value from the position setting device 2. On the other hand, in the embodiment shown in FIG. 1, the value of the oil column S, which is the control amount from the position detector 11, is given to the compensation value generation circuit 6. According to the present embodiment, when the stroke length is switched from the short stroke state to the long stroke state, the proportional gain increases even if the stroke length is short, so that the time required to reach the desired stroke length can be shortened. .

As described above, in each of the embodiments, the stroke length is obtained by detecting the position of the piston of the hydraulic cylinder to perform oil column compensation, but the amount of hydraulic oil supplied to the hydraulic cylinder is detected. Of course, the oil column compensation may be performed.

[0017]

As described above, according to the present invention, even if the amount of hydraulic oil supplied to the cylinder increases and the response becomes slow,
Since the proportional gain in the feedback control is set to be large by the gain compensating means, highly accurate and stable control can be performed even if the stroke length is largely changed. Further, since the delay of the response due to the increase of the stroke length can be compensated with a simple structure, it is easy to realize a mill capable of switching between large and small diameter rolls. Further, since a constant response performance can be obtained regardless of the height of the oil column corresponding to the position of the piston of the cylinder, it is easy to realize the automatic plate thickness control in the rolling mill.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system of a hydraulic pressure reducing device for a rolling mill according to an embodiment of the present invention.

FIG. 2 is a graph showing characteristics of a compensation value generation circuit 6 shown in FIG.

FIG. 3 is a schematic cross-sectional view showing a mechanical configuration of a rolling mill using the hydraulic pressure reduction device shown in FIG.

FIG. 4 is a graph showing response characteristics with the length of an oil column in the hydraulic cylinder 10 shown in FIG. 1 as a parameter.

FIG. 5 is a block diagram showing a control system of a hydraulic pressure reducing device for a rolling mill according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic plate thickness control device 2 Position setting device 3 Subtraction circuit 4 Controller 5 Gain compensation means 6 Compensation value generation circuit 7 Oil column compensation circuit 8 Servo amplifier 9 Servo valve 10 Hydraulic cylinder 11 Position detector 12 Rolled material 13 Plate thickness detector 14 Load cell 20,21 Work roll

Claims (1)

[Claims] 1. A rolling mill which is feedback-controlled so that a difference between the work roll and a position of a piston of the cylinder is a control amount so that a difference from a preset target value becomes small in order to displace the work roll by a rolling means using the cylinder. A hydraulic pressure reducing device for a rolling mill, comprising: a gain compensating means for setting a proportional gain in feedback control such that the proportional gain increases as the amount of hydraulic oil supplied to the cylinder increases.