JP2002079304A - Method and equipment for hot rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing the generation of the heat crown of rolling rolls when performing the cooling of the surface of the rolled stock just before the roll bite in a hot finishing mill and uniforming finished thickness in the width direction of a rolled stock and equipment which is suitable to perform the method. SOLUTION: In a hot-rolling method by which rolling is performed after cooling the surfaces of the rolled stock just before the roll bites in the hot finishing mill, by supplying a cooling medium onto the surface of the rolling rolls by such a cooling medium supply distribution in the axial direction of the roll eliminating a temperature distribution in the axial direction of the roll, generated on the surface of the rolling rolls caused by the cooling, the rolling rolls are cooled. In this hot-rolling equipment, the nozzles of a rolling roll cooling device are arranged in the axial direction of the roll in a different spraying arrangement against a spraying arrangement in the width direction of a sheet of the nozzles of a rolled stock cooling device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling method and equipment for producing a hot rolled steel sheet or the like.

[0002]

2. Description of the Related Art For the purpose of preventing roughening of rolling rolls and defects of scale, there are known several techniques for cooling the surface of a rolled material immediately before a roll bite and then rolling.

[0003] The technique described in Japanese Patent Application Laid-Open No. 4-200903 discloses a technique in which a hot-rolled material is brought into contact with a refrigerant immediately before it enters a roll bite for the purpose of suppressing the roughening of the rolling roll. This is a method in which hot rolling is performed while the surface is cooled.

The technique described in Japanese Patent Application Laid-Open No. 5-50131 is a technique for removing secondary scale to prevent scale flaws, and discloses a descaling device provided between finishing stands of a hot finishing mill. Have been. This descaling device is understood to be a kind of cooling device.

Japanese Patent Application Laid-Open No. 7-68310 includes a rolled material cooling header for cooling a rolled material immediately before a roll bite, an oil rolling header for supplying a lubricant to a rolling roll for performing lubricating rolling, and a roll cooling header. A hot rolling facility is disclosed.

[0006]

As shown in the above-mentioned publication, the cooling device installed immediately before the rolling roll includes a header pipe 2 as shown in FIG.
In general, the one in which a large number of injection nozzles 2b are attached to a is used. FIG. 7 schematically shows the cooling power distribution on the surface of the object to be cooled which is cooled by the cooling device shown in FIG. 4, where the cooling power is highest immediately below the nozzles, and the cooling power is between the adjacent nozzles. Water interferes with each other and the cooling capacity is reduced.
As shown in FIG. 5, when the rolled material is cooled immediately before the hot finishing mill roll bite using such a cooling device, a part of the cooling water directly hits the rolling rolls. As a result, a temperature distribution (temperature unevenness) having a waveform as shown in FIG. 6 occurs in the axial direction of the rolling roll corresponding to the position of the nozzle of the rolled material cooling device. Then, the heat crown of the rolling roll corresponding to such a temperature distribution is transferred to the thickness of the rolled material, and the finished plate thickness in the width direction of the rolled material is changed as shown in FIG.
The waveform shown in FIG. That is, since the diameter of the rolling roll is large in the high-temperature portion and thin in the low-temperature portion, the thickness of the rolled material rolled in the high-temperature portion of the rolling roll is thin, and the thickness of the rolled material rolled in the low-temperature portion of the rolling roll is small. It gets thicker.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to prevent the occurrence of heat crown of a roll when a surface of a rolled material is cooled immediately before a roll bite of a hot finishing mill. Another object of the present invention is to provide a method capable of equalizing a finished plate thickness in a rolled material plate width direction and an apparatus suitable for carrying out the method.

[0008]

Means for Solving the Problems In order to solve the above problems, the hot rolling equipment and method of the present invention have the following features.

(1) In a hot rolling method in which the surface of a rolled material is cooled just before a hot finishing rolling mill roll bite and then rolling is performed, a temperature distribution in a roll axis direction generated on the surface of the rolling roll due to the cooling. A hot-rolling method, characterized in that a cooling medium is supplied to a surface of a rolling roll with a cooling medium supply distribution in a roll axis direction so as to solve the problem, and the rolling roll is cooled.

(2) A hot-rolling facility characterized in that the nozzles of the rolling roll cooling device are arranged in the roll axis direction with a different spraying arrangement than the spraying arrangement of the nozzles of the rolled material cooling device in the plate width direction. .

(3) The nozzles of the rolling roll cooling device are arranged in the roll axis direction such that the nozzles of the rolled material cooling device are alternately staggered with respect to the spraying arrangement of the nozzles in the plate width direction. Item 3. The hot rolling equipment according to item 2.

[0012]

FIG. 1 is a side view showing an embodiment of the hot rolling equipment of the present invention, and FIG. 2 is a view taken along the line AA in FIG. The hot rolling equipment of the present invention has a rolled material cooling device 2 for cooling the rolled material 5 and a rolling roll cooling device 1 for cooling the rolling roll 3 immediately before the roll bite of the hot finishing mill.

The rolled material cooling device 2 is for cooling the rolled material 5 immediately before the roll bite of the hot finish rolling mill. In this example, the rolled material cooling device 2 cools the rolled material 5 just before the roll bite of the hot finish rolling mill. It comprises a header 2a arranged along the width direction and a plurality of nozzles 2b provided at appropriate intervals along the longitudinal direction of the header 2a.

The rolling roll cooling device 1 includes a rolling roll 3
In this example, the header 1a is arranged along the axial direction facing the roll and a plurality of nozzles 1b provided at appropriate intervals along the longitudinal direction of the header 1a. Be composed. Here, as shown in FIG. 2, the rolling roll cooling nozzle 1b is disposed so as to be located between the rolled material cooling nozzles 2b in the rolling roll axial direction.

According to the positional relationship between the two nozzles,
The temperature distribution (temperature unevenness) of the waveform in the roll axis direction generated on the surface of the rolling roll 3 by the cooling water from the rolled material cooling device 2 can be eliminated by the cooling water from the rolling roll cooling device 1. In addition, components commonly used before and after the rolling roll 3, such as a roll cooling water drainer 4, a side guide and a stripper guide (not shown), may be used together within a range that does not hinder the implementation of the present invention. Is perfectly acceptable. However, it is necessary that the wiper 4 for the roll cooling water always has a width that covers at least the width of the rolled material 5.

In the hot rolling method of the present invention, the generation of heat crown of the roll 3 when cooling the surface of the rolled material 5 immediately before the roll bite of the hot finishing mill is prevented, It has the basic effect of making the finished plate thickness uniform in the plate width direction, and furthermore, the rolled material 5 is cooled just before the roll bite of the hot finish rolling mill to lower its surface temperature, so that the surface roughness of the roll 3 is reduced. I do. In addition, the growth of the secondary scale is suppressed, and the effect of descaling is added, so that the scale defects are reduced. It should be noted that the present invention and hot lubrication may be performed simultaneously. Supplying the lubricant to the rolling roll 3 also has a cooling effect of the rolling roll 3, and is used to generate the cooling water of the rolled material 5 used immediately before the roll bite of the hot finishing mill. Roll 3
It is also possible to eliminate the heat crown pattern.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a hot finishing mill will be described. The hot finish rolling mill of the present embodiment is provided with a finishing mill group including seven rolling mills, and a rough bar having a thickness of 30 to 40 mm is finish-rolled by a finishing rolling mill.
mm hot-rolled steel sheet. A rolled material cooling device 2 as shown in FIG. 1 was installed immediately before the first to fifth roll bites of the finishing mill.

As shown in FIG. 3 of the comparative example, the nozzle 2b of the rolled material cooling device 2
When arranged so as to be directly below b, the finished plate thickness in the width direction of the rolled material sheet became corrugated in accordance with the arrangement of the nozzle 2b of the rolled material cooling device 2. Here, the widthwise nozzle arrangement pitch of the nozzles 2b of the rolled material cooling device 2 is 130 mm, and the number of nozzles is 15. The nozzle 2b of the rolled material cooling device 2
Was exactly the same as the pitch of the nozzle 1b of the rolling roll cooling device 1. In the case of a hot-rolled steel strip having a finished plate thickness of 3 mm, the height of the wave peak in the width distribution of the finished plate thickness is 10 to 1
It reached 5 μm.

Therefore, the arrangement of the nozzles 2b of the rolled material cooling device 2 is changed so that the nozzles 2b of the rolled material cooling device 2 are located between the nozzles 1b of the rolling roll cooling device 1 as shown in FIG. When the staggered arrangement was used, the waveform pattern disappeared from the finished plate thickness in the rolled material plate width direction.

[0020]

According to the present invention, by cooling the rolled material immediately before the roll bite, it is possible not only to reduce the surface roughness and scale defects of the roll, but also to generate the heat generated in the roll by the cooling of the rolled material. Since the crown can be eliminated by cooling the rolling rolls, the finished plate thickness in the plate width direction of the rolled material can be made uniform.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the hot rolling equipment of the present invention.

FIG. 2 is a view of the hot rolling plant shown in FIG. 1 taken along line AA.

FIG. 3 is a side view of a rolling roll cooling device and a rolled material cooling device of a hot rolling facility of a comparative example.

FIG. 4 is a side view showing a general cooling device.

FIG. 5 is a side view showing a conventional hot rolling equipment.

FIG. 6 is a diagram showing an axial temperature distribution of a rolling roll generated by cooling of a rolled material and a finished plate thickness distribution in a strip width direction of the rolled material.

FIG. 7 is a diagram showing distribution of cooling power generated by a general cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll roll cooling device 1a Roll roll cooling header 1b Roll roll cooling nozzle 2 Rolled material cooling device 2a Rolled material cooling header 2b Rolled material cooling nozzle 3 Roll roll 4 Drain wiper 5 Rolled material 6 Rolled material traveling direction

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Kamioka 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Koichi Tsutsumi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (3)

[Claims] In a hot rolling method for cooling a surface of a rolled material just before a hot finish rolling mill roll bite and then performing rolling, a temperature distribution in a roll axis direction generated on a rolling roll surface due to the cooling is determined. A hot rolling method comprising supplying a cooling medium to the surface of a rolling roll with a cooling medium supply distribution in a roll axis direction to eliminate the cooling, and cooling the rolling roll. 2. A hot-rolling facility wherein the nozzles of a rolling roll cooling device are arranged in the roll axis direction with different spraying arrangements than the spraying arrangement of the nozzles of the rolled material cooling device in the plate width direction. 3. The roll roll cooling device nozzles are arranged in the roll axis direction such that the nozzles of the rolled material cooling device are staggered alternately with respect to the spraying arrangement of the nozzles in the plate width direction. 3. The hot rolling equipment according to 2.