JPH105804A - Method for controlling dimension of wide-flange steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the bias of web of a wide-flange steel by cooling a flange lower part on the bottom part or the top part of the wide flange steel and controlling the dimension of the flange width in a process after intermediate rolling and before finishing rolling. SOLUTION: This cooling device is composed of three cooling zones, and each zone is arranged with many cooling jetting nozzles in the rolling direction of this H-shape steel. When the bias is made larger, cooling is increased, when the bias is made smaller, cooling is reduced. The power of cooling depends on its jetting time of a cooling water, the H-shape steel is cooled during movement of the steel, and the cooling time is controlled by on/off of the cooling water per each zone unit. The position to jet the cooling water is aimed at the flange lower part of the H-shape steel. In the flange lower part of the next process finishing by cooling the lower part, the longitudinal elongation of the steel is restricted, the steel is elongated to the width direction of the flange and this is acted to the direction of solving the web bias.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently improving the sectional dimensional accuracy of an H-section steel manufactured by continuous rolling using a universal mill.

[0002]

2. Description of the Related Art Generally, an H-section steel is roughly formed by a breakdown rolling mill, rolled by several intermediate coarse universal rolling mills and an edger rolling mill, and hot-rolled to a predetermined size by a finishing universal rolling mill. It is formed and cut to a predetermined length by a hot sawing machine. FIG. 1 shows the cross-sectional dimensions of an H-section steel. However, in the case of continuous rolling by a universal mill, there is no constraint on the upper and lower sides of the flange, so a problem occurs in that a dimensional difference (web deviation) between a and b in the figure occurs. Was out.

[0003] In the case of a <b, the table before the mill is raised to raise the bite angle downward, but in the case of a> b, the upper and lower horizontal rolls of the finishing mill roll are conventionally moved. This problem has been dealt with by performing a so-called pass line adjustment that shifts in the rolling (horizontal) direction.

[0004]

However, the above countermeasures have the following problems.

(1) The mill must be stopped in order to reset the rolls in the horizontal direction, and the line must be stopped.

(2) Since the roll itself is adjusted, it also acts on the middle portion where there is no web deviation, and conversely, the web becomes uneven in the middle portion.

That is, the cause of the occurrence of the web deviation is that when the H-section steel is continuously rolled, since the top and bottom portions are rolled in a cantilever state, a free state occurs at the end of the steel material. As described above, since the upper and lower portions of the flange are not constrained by the rolling roll, web deviation often occurs at the top portion or the bottom portion.

[0008]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and the gist of the present invention is to provide a method for controlling the cross-sectional dimension of an H-section steel in a process after intermediate rolling and before finishing rolling. A method for controlling the cross-sectional dimension of an H-beam, comprising cooling a lower portion of a flange of the H-beam for the purpose of preventing web deviation.

[0009] In the above-mentioned method for controlling the sectional size of an H-section steel, the lower portion of the flange of the H-section steel is cooled at the bottom and / or top of the steel material.
This is a method for controlling the cross-sectional dimension of a section steel.

That is, in the present invention, in the continuous rolling step of the H-section steel, when the lower section of the flange is cooled after the intermediate rolling and the finish rolling is performed, the extension of the lower section of the flange in the rolling direction of the H-section steel is suppressed, and the flange width direction is reduced. It is based on the finding that it extends.

The details will be described below with reference to the drawings.

FIG. 2 is a diagram showing one embodiment of a cooling device to which the present invention is applied.

The cooling device is composed of three cooling zones of about 7 m, each having a number of cooling water discharge nozzles arranged in the rolling direction of the H-section steel. The reason for dividing the zone into multiple zones is that depending on the degree of web deviation, it is necessary to control the strength of cooling.If the deviation is large, the cooling must be increased, and if the deviation is small, the cooling must be reduced. There is. The strength of the cooling depends on the time of spraying the cooling water.
The cooling of the section steel is performed during the movement of the steel material. Therefore, the cooling time is controlled by turning on and off the cooling water in each zone. Here, the on / off operation is performed in units of zones.

The position where the cooling water is blown is aimed at the lower part of the flange of the H-section steel as shown in FIG. By cooling the lower part of the flange, the lower part of the flange is restrained from extending in the longitudinal direction of the steel material, extends in the width direction of the flange, and acts in a direction in which the web deviation is eliminated at the time of finishing the next step.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[0016]

The results of applying the method of the present invention on an actual machine are shown below.

The applied steel material has a web height of 200
mm × flange width 200 mm, web thickness 8 mm, flange thickness 12 mm, length of about 220 m, and about 220 m in length. As a cooling device, about 7 m per zone, cooling zone of 3 zones, 34 zones per side of one zone Nozzles are installed. 1
The water volume on one side of the zone is about 3000 l / min.

When the above-mentioned steel material was finish-rolled without cooling, the web deviation at the top and bottom portions was +5 mm. After cooling with cold water for 13 seconds and performing finish rolling, the web bias was zero.

[0019]

According to the method of the present invention, when preventing the deviation of the web of the H-section steel, there is no need to stop the line as in the prior art, the rate of occurrence of the steel material having the improper web deviation is reduced to 1/10 of the conventional, and the yield is improved. And also contributed to the improvement of the operation rate.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the cross-sectional dimensions of an H-section steel.

FIG. 2 is a diagram showing an example of a cooling device for applying the method of the present invention.

FIG. 3 is a diagram showing an aspect in which cooling water is sprayed on an H-section steel.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Akihiro Nishi, Kimitsu Works, Kimitsu City, Nippon Steel Co., Ltd. Inside Nippon Steel Corporation Kimitsu Works (72) Inside the steelworks

Claims (1)

[Claims] 1. A method for controlling a cross-sectional dimension of an H-section steel, comprising: a step of controlling a bottom portion and / or a top portion of an H-section steel in a step after intermediate rolling and before finish rolling for the purpose of preventing web deviation. A method for controlling a cross-sectional dimension of an H-section steel, characterized by cooling the steel.