JPH1147814A - Method for controlling meandering of steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the abrupt meandering which occurs when the front end of a steel sheet passes by a fore stage stand by detecting the thrust force of work rolls under hot finish rolling and controlling the rolling down position difference between the work side and drive side of the work rolls so as to make the thrust force zero. SOLUTION: At the time of meandering control, selector valves 6 of axial shift cylinders 4 of the work rolls 2 are closed and the pressure changes of right and left hydraulic chambers are detected by pressure detectors 5. The thrust force acting on the work rolls 2 is then calculated based on the detect value by arithmetic units 9 and rolling down position controllers (chocks) 10 of backup rolls 3 are commanded to control the rolling down position difference so as to make the thrust force zero. As a result, the meandering detection and rolling down position judgment in a short period of about 0.3 to 1.0 second are made possible and the perfect prevention of meandering is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a meandering control method for a steel sheet in a tandem rolling mill.

[0002]

2. Description of the Related Art In hot rolling, a steel sheet tends to meander when there is a difference between a reduction ratio of a work side and a reduction ratio of a drive side in a rolling stand. When the steel plate is being rolled at the preceding stage of the stand, a backward tension is generated, and the meandering amount can be suppressed. However, when the tail end passes through the front stand, the rear tension is lost, and the steel sheet suddenly meanders. When the meandering amount increases, the steel plate hits the side guide, and the edge part is broken and rolled, or the steel plate is bent, resulting in damage to the roll of the rolling mill and flaws in the product during the next material rolling And defective products are generated. In addition, the production efficiency is reduced due to the roll change. For this reason, conventionally, various techniques for preventing meandering of a steel sheet in a hot rolling finishing mill have been proposed.

In general, the amount of meandering is detected by a difference in rolling load between the work side and the drive side (Japanese Patent Laid-Open No. Sho 60-6 / 1985).
No. 213), a meandering amount is measured using an optical meter, and based on the measurement, the rolling positions of the work side and the drive side are instantaneously controlled to suppress the meandering. Japanese Patent Application Laid-Open No. Sho 61-144209 discloses that while a rolled steel strip is constrained by front and rear stands, a thrust force acting on a work roll of a front stand is continuously measured, and rolling is performed. Predicts the meandering direction of the tail end of the rolled steel strip when the tail end of the steel strip passes through the former stand, and based on that, corrects the lowering of the rear stand so that the thrust force of the work roll of the former stand becomes zero. A method for preventing meandering of the tail end of a rolled steel strip is disclosed. In this technology, the thrust force (thrust, axial force) of the work roll of the front stage stand
Is controlled by applying a reverse thrust force in the next stage so that is zero, so that the thrust force is not released, and the meandering control after the tail end of the steel sheet has passed through the previous stand in the final stand cannot be performed. There is.

[0004]

In the prior art for detecting the occurrence of meandering and controlling the meandering after the tail end of the steel sheet passes through the front stand, the meandering is performed in a short time such as 0.3 to 1.0 second. It is necessary to perform the detection and the determination of the rolling position, which has the effect of suppressing the meandering amount. However, the meandering cannot be completely prevented, and it is impossible to completely prevent the breaking of two steel plates to 100%. Was.

[0005] Means for controlling the thrust force of the preceding stand to zero to zero cannot control the meandering in the final stand after passing through the preceding stand. An object of the present invention is to overcome the above-mentioned drawbacks of the prior art, suppress the meandering of the steel sheet in the final stand, and completely prevent the two sheets from breaking.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and detects the thrust force of a roll during rolling in a finishing mill of hot rolling, and this thrust force becomes zero. Thus, a meandering control method for a steel sheet is characterized by controlling the difference between the roll-down positions of the work roll and the drive side of the work roll. That is, the thrust force generated in the work roll of the stand before the tail end of the steel sheet passes through the preceding stand is detected, and the work side and the drive side of the work roll of the stand of the rolling mill are set so that the thrust force becomes zero. By controlling the difference in the rolling position of the steel sheet, meandering of the steel sheet, which is suddenly generated when the tail end of the steel sheet passes through the preceding stand, is prevented. The thrust force measuring means in the present invention can be detected, for example, from the pressure of the shift cylinder of the work roll shift device.

[0007]

According to the present invention, the thrust force acting on a work roll during rolling is detected by, for example, the pressure of a work roll shift cylinder, and the meandering generated when the tail end of the steel sheet passes through the front stand is detected. By detecting in advance and controlling the difference in the rolling position between the work side and the drive side of the work roll so that the thrust force of the work roll becomes zero, abrupt change that occurs when the tail end of the steel sheet passes through the preceding stand. Meandering can be prevented.

Hereinafter, description will be made with reference to the drawings. FIG.
It is a figure showing the meandering control device of the present invention. The steel plate 1 is rolled by the work roll 2. The work roll 2 is backed up by the backup roll 3, and the rolling position control device (chock) 10 controls the rolling position of the backup roll.

The shift cylinder 4 is provided with a hydraulic pump 7,
The work roll 2 is shifted in the axial direction by the hydraulic tank 8 and the switching valve 6. When the thrust force of the work roll 2 is detected by the pressure detection of the present invention, the switching valve 6 is closed, and the thrust force is detected from the change in the pressure on the left and right of the shift cylinder and the cross section of the hydraulic chamber of the cylinder. That is, the hydraulic pressure of the shift cylinder 4 is detected by the pressure detector 5 and input to the arithmetic unit 9. The arithmetic unit 9 calculates a thrust force acting on the work roll 2 based on the detected pressure value. The reduction control device 10 is set so that the thrust force becomes zero.
And outputs the command of the rolling position difference to control the rolling position difference.
Thereby, it is possible to prevent the occurrence of meandering when the tail end of the steel plate 1 passes through the front stand.

FIG. 2 is a graph showing meandering control according to an embodiment of the present invention. Open circles indicate the case where the control of the present invention is not performed, and black circles indicate the case where the control is performed. By implementing the present invention, meandering of the steel sheet could be effectively prevented.

[0011]

According to the present invention, it is possible to greatly reduce the amount of meandering at the tail end of the steel sheet, to prevent the steel sheet from breaking due to meandering beforehand, and to perform useless roll replacement. It has become possible to operate stably without the need. In addition, no product flaws occurred before the roll replacement, and the yield was improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a meandering control device of the present invention.

FIG. 2 is a graph showing meandering control according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 2 Work roll 3 Backup roll 4 Shift cylinder 5 Pressure detector 6 Switching valve 7 Hydraulic pump 8 Hydraulic tank 9 Computing device 10 Rolling-down position control device

Claims (1)

[Claims] In a finishing mill for hot rolling, a thrust force of a roll being rolled is detected, and a difference between a reduction position of a work side and a reduction position of a drive side of the work roll is controlled so that the thrust force becomes zero. A meandering control method for a steel sheet.