JPH11197707A - Method for correction shape of tip part of hot-rolled steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a tip part of steel plates having various thickness into an appropriate shape by regulating the spray pressure of high-pressure spray water to be spray on the tip part of the steel plate according to the thickness of a hot-rolled steel plate. SOLUTION: The information on the thickness of a steel plate 3 is transmitted to a spray pressure control device 9 as the signal from a computing unit to control the operational condition, etc., of a hot rolling mill, and the spray pressure of high-pressure spray water 8 from a spray header 4 is regulated by controlling the operation of a valve 5 or a pump 6 of a high-pressure spray device 7 based on the information on the thickness. Because the high-pressure spray water is sprayed by changing the spray pressure according to the thickness of the steel plate, an operation case is avoided where the upward of the tip part if promoted due to excessively high spray pressure on a thin steel plate, or the shape correction of the tip part becomes insufficient due to excessively low spray pressure on a thick steel plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the shape of a hot-rolled steel sheet after finish rolling at the tip.

[0002]

2. Description of the Related Art In a hot rolling process for a steel sheet, as shown in FIG. 5, a hot-rolled steel sheet 3 (hereinafter simply referred to as a steel sheet) that has been finish-rolled by a finishing mill 1 is subjected to the finishing mill. The roller 1 travels on a transfer table 2 (hereinafter, referred to as a run-out table) on an output side of the roller 1 and is wound into a coil by a winder 10 via a pinch roll 11. Here, the tip of the steel sheet after the finish rolling is likely to be warped. If the tip of the steel sheet is wound around the winder 10 in a state in which the warpage is generated, the head may be wound in a state where the tip is broken, or the head may be warped. If the degree is severe, the winder 10 cannot be wound around, leading to an accident. Therefore, normally, on the exit side of the finishing mill 1, the upward warpage is corrected by injecting high-pressure spray water 8 from the spray header 4 installed above the run-out table 2 toward the tip. ing.

[0003]

However, a steel plate having a small thickness is about 1 mm, and a steel plate having a thickness of about 20 mm.
The method of spraying high-pressure spray water with a conventional high-pressure spray device at a constant pressure is difficult to perform appropriate shape correction in the same manner regardless of thin or thick materials. there were.

[0004] That is, if a pressure and water amount spraying device suitable for correcting the shape of a thick material is used for a thin material, the pressure and the water amount are too large. As a reaction, the tip of the steel plate jumps upward from the pass line, and the tip is warped. Conversely, if a pressure and water volume spray device suitable for shape correction of thin materials is used for thick materials, the pressure and water volume are small,
Sufficient tip shape correction cannot be performed.

[0005] It is an object of the present invention to propose a technique capable of appropriately correcting the shape of the distal end portion of steel plates having various thicknesses.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for correcting the shape of a steel plate tip by spraying high pressure spray water from above onto the tip of the steel sheet at the outlet side of the hot finishing mill. And adjusting the injection pressure according to the thickness of the hot-rolled steel sheet.

Here, two or more sets of high-pressure spray devices having different injection pressures of high-pressure spray water are arranged on the exit side of the hot finishing mill, and these high-pressure spray devices are selectively used according to the thickness of the steel sheet. Is also possible.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a final stand 1 comprising a backup roll 1a and a work roll 1b and a run-out table 2 on the exit side in a finishing mill of a hot rolling facility. A high-pressure spray device 7 for spraying high-pressure spray water 8 on the tip of the passed steel plate 3 is arranged. The high-pressure spray device 7 includes a spray header 4,
A valve 5 and a pump 6 are provided, and the high-pressure spray water 8 is sprayed from the spray header 4 to correct the shape of the tip. At that time, it is important to adjust the injection pressure of the high-pressure spray water 8 according to the thickness of the steel plate 3.

That is, the injection pressure of the high-pressure spray water is controlled by the injection pressure control device 9 in the high-pressure spray device. Information about the thickness of the steel sheet 3 is transmitted as a signal from a computing unit (not shown) for controlling the operating conditions of the hot rolling equipment to the injection pressure control device 9 and based on the thickness information, the high-pressure spray device 7 is used. By controlling the operation of the valve 5 or the pump 6, the injection pressure of the high-pressure spray water 8 from the spray header 4 is adjusted. Incidentally, the time when the tip of the steel plate 3 passes through the spray header 4 is detected by a plate detector (not shown) such as a photo sensor installed on the exit side of the finishing mill, and based on this detection signal. To operate the high-pressure spray device 7.

Therefore, since the injection pressure of the high-pressure spray water is changed and sprayed depending on the thickness of the steel sheet, the injection pressure is too high for the thin steel sheet to promote the upward curving shape at the tip, and conversely, the injection pressure for the thick steel sheet is increased. The conventional operating case, in which the tip is too low and the tip shape correction is insufficient, is avoided.

Further, the adjustment of the injection pressure of the high-pressure spray water is not limited to the above example, but may be performed by using two or more sets of high-pressure spray devices as shown in FIG. That is, on the exit side of the final stand 1 of finish rolling, a plurality of sets of high pressure spray water having different injection pressures, two sets of high pressure spray devices 7a and 7b in the illustrated example, are arranged, and an appropriate injection pressure according to the thickness of the steel sheet. As a result, it is possible to variously change the injection pressure of the high-pressure spray water by selectively using the high-pressure spray device 7a or 7b. In this example, since the injection pressure of each high-pressure spray device may be constant, it is advantageous in that the structure of the high-pressure spray device can be simplified.

In order to set the injection pressure of the high-pressure spray water in accordance with the thickness of the steel sheet, the operation is performed in advance by changing the injection pressure of the spray water for steel sheets of various thicknesses. The injection pressure at which the rate becomes the lowest may be determined for each plate thickness. FIG. 3 shows the relationship between the injection pressure of the high-pressure spray water and the occurrence rate of breakage in the case where the thickness of the steel plate is 2 mm or less and in the case where it exceeds 2 mm. From FIG. 3, when the thickness of the steel plate is 2 mm or more,
The injection pressure is preferably from 7 to 13 kgf / cm ^2, and when the thickness of the steel plate is more than 2 mm, the injection pressure is preferably at least 17 kgf / cm ² .

[0013]

EXAMPLE As shown in FIG. 1, hot rolling was performed while correcting the shape of the tip of a steel sheet. That is, when hot rolling a thin material having a thickness of 2.0 mm or less, the injection pressure of the high-pressure spray water is 10 kgf / cm ² , and the thickness is 2.
For a thick material exceeding 0 mm, the spray pressure of high-pressure spray water was set to 20 kgf / cm ² and sprayed to the tip (length 30 m) of each steel plate.

Further, for comparison, in the same hot rolling, the spray pressure of the high-pressure spray water was set to 15 kgf / cm ² for the steel plates of all the thicknesses, and the steel plates were sprayed to the tips of the steel plates.

FIG. 3 shows the results of an investigation on the incidence of shape defects at the tip of the steel sheet when hot rolling 100 steel sheets under the above conditions. In addition, the shape of the front end of the steel plate was inspected by a rewinding line in the next step, and when the head was broken at the front end, it was determined to be defective. As shown in FIG. 4, it can be seen that the incidence of defective shape at the tip of the steel sheet is extremely low by the method of the present invention.

The high-pressure spray device 7a shown in FIG.
The injection pressure of high pressure spray water at 10kgf / cm^Two, That
And the injection pressure of the high-pressure spray water in 7b is 20 kg
f / cm ^TwoHigh-pressure steel for thin materials with a thickness of 2.0 mm or less.
Playing device 7a, and a thick material having a plate thickness exceeding 2.0 mm
The high-pressure spray device 7b was applied to the material.
Alternatively, the same result as the result shown in FIG. 3 was obtained.

[0017]

According to the present invention, irrespective of the thickness of the steel plate, the shape of the front end can be properly corrected, and the defective shape of the front end of the steel plate can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a method for correcting the shape of a steel plate tip portion according to the present invention.

FIG. 2 is a schematic view showing another shape correction method of the present invention.

FIG. 3 is a graph showing the effect of the injection pressure of a high-pressure spray on the incidence of head breakage of a steel plate.

FIG. 4 is a graph showing the results of a survey on the incidence of shape defects at the tip of a steel plate.

FIG. 5 is a schematic diagram showing an arrangement of equipment from a hot finish rolling mill outlet side to a winding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Final stand 2 Runout table 3 Steel plate 4 Spray header 5 Valve 6 Pump 7, 7a, 7b High-pressure spray device 8 High-pressure spray water 9 Injection pressure control device

Claims (2)

[Claims] On the outlet side of a hot finish rolling mill, when the high-pressure spray water is sprayed from above onto the tip of a hot-rolled steel sheet to correct the shape of the tip of the steel sheet, the injection pressure of the high-pressure spray water is increased by: A shape correcting method for a tip of a hot-rolled steel sheet, wherein the shape is adjusted according to a thickness of the hot-rolled steel sheet. 2. The high-pressure spray device according to claim 1, wherein two or more sets of high-pressure spray devices having different injection pressures of high-pressure spray water are arranged on the outlet side of the hot finishing mill. A method for correcting the shape of the tip of a steel sheet, which is selectively used.