JP2004009134A - Method for rolling wide flange shape having narrow flange width - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To roll a wide flange shape having narrow flange width the flange width of which is 1/4 to 1/10 of the web height at high efficiency. <P>SOLUTION: A product having target dimensions is obtained by reducing the web and the flanges with a universal mill and the flange width with an edger mill after making a slab of a base stock having a rectangular section into a rough shape slab by rolling by one approximately H-shaped caliber. When making the rough shape slab by rolling by one approximately H-shaped caliber, rolling is carried out without rotating the slab of the base stock. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for rolling an H-section steel having a narrow flange width having a flange width in a range of 1/4 to 1/10 of a web height, and more particularly, to a high-efficiency rolling.
[0002]
[Prior art]
A section steel having a flange such as an H-section steel is generally manufactured in a rolling line having a breakdown rolling mill, a universal rolling mill, and an edger rolling mill. The raw steel slab that has exited the heating furnace is first rolled by a breakdown rolling mill BD, which is a double rolling mill, into a shape suitable for the target product dimensions. Subsequently, the thickness is reduced and the flange end is formed in the coarse universal rolling mill group including the rough universal rolling mill U and the edger rolling mill E. Further, the flange is formed at a right angle by the finishing universal rolling mill F, and an H-shaped product is obtained.
[0003]
As a steel slab as a material, a steel slab having an H-shaped cross section called a beam blank, a slab having a rectangular cross section, or the like is generally used. Among them, a method disclosed in Japanese Patent Publication No. 7-61482, for example, is known as a method of obtaining a roughly H-shaped steel slab using a slab as a raw material. This technique involves, as shown in FIG. 6, for example, reducing the short side of the slab with a plurality of holes to increase the thickness in the vicinity of the reduced portion, thereby bringing the cross-sectional shape closer to the H-shape. The slab is turned by 90 ° and rolled with a pair of substantially H-shaped cavities to obtain a coarse shaped slab having a desired cross-sectional shape.
[0004]
Further, conventional H-section steels generally have a dimensional ratio in which the flange width is 1/3 or more of the web height. Particularly, in a large-section H-section steel having a web height of 500 mm or more, 1/4 of the web height is required. There is no example in which an H-section steel having the following flange width has been commercialized. Therefore, a rolling method suitable for such a narrow flange width H-section steel has not been studied so far.
[0005]
[Problems to be solved by the invention]
The present inventors have rolled out a conventional method of rolling a crude steel slab of H-section steel using a slab as a material in order to roll a narrow flange width H-section steel having a flange width of 1/4 of the web height. The application of the technology of JP-A-7-61482 was examined. As a result, it became clear that there were the following problems.
[0006]
First, it has been found that in the conventional technique, the short side of the slab is rolled using a plurality of holes, so that there is a problem that the number of rolling passes is large and the rolling efficiency is poor. Furthermore, even if the short side of the slab is pressed down to bring the cross-sectional shape closer to the H-shape, the cross-sectional area of the portion of the slab that hits the flange is reduced by rolling it 90 ° and rolling it with a substantially H-shaped hole. It turned out to be. Since the reduction in the cross-sectional area of the flange is larger than that of the conventional H-section steel, it is necessary to form the flange in consideration of this reduction when rolling down the short side of the slab. Since the number of times was required, there was a concern that the rolling efficiency would be further deteriorated.
[0007]
As described above, there are many problems in applying the conventional H-beam breakdown rolling method to a narrow flange width H-beam as it is, and it has become clear that a new rolling method needs to be developed.
[0008]
However, the H-section steel with a flange width smaller than 1/10 of the web height is more likely to be rolled in a state where the material to be rolled is shifted left and right with respect to the roll in rough and universal rolling, and the torsion of the material to be rolled is high. In reality, mass production is not possible because there is a possibility that the shape defect such as, or the like, or the flange portion is rolled between horizontal rolls to cause roll damage. For this reason, the narrow flange width H-section steel requiring the above-mentioned new rolling method is intended to have a flange width of 1/4 to 1/10 of the web height.
[0009]
Therefore, the present invention provides a method for rolling a narrow flange width H-section steel which enables highly efficient rolling of a narrow flange width H-section steel having a flange width of 1/4 to 1/10 of the web height. The purpose is to:
[0010]
[Means for Solving the Problems]
The present inventors have developed a method for efficiently rolling a crude steel slab of a narrow flange width H-section steel by using a numerical calculation or a model rolling mill having a size several times smaller than that of an actual machine. As a result of conducting a rolling experiment and a rolling test using an actual machine and conducting various studies, a rolling method of the present invention having the following features has been invented.
[0011]
(1) A raw steel slab having a rectangular cross section is rolled into a roughly shaped steel slab by using one substantially H-shaped die, and then the web and flange are reduced by a universal rolling mill, and the flange width is reduced by an edger rolling mill. Method of rolling narrow flange width H-section steel to obtain products of target dimensions.
[0012]
(2) A method for rolling a narrow flange width H-section steel in which a raw steel slab is rolled without rolling when a rough slab is rolled using one substantially H-shaped die.
[0013]
(3) After rolling the short side of the raw steel slab having a rectangular cross section with a pair of dies to adjust the width of the raw slab, rolling the raw steel slab with one substantially H-shaped die and forming a coarse steel slab Method of rolling narrow flange width H-section steel.
[0014]
(4) A method for rolling a narrow flange width H-section steel in which rolling with one substantially H-shaped die is completed before the increase in flange leg length is saturated.
[0015]
(5) The rolling with one hole having a substantially H shape is completed in a state where the flange leg length is smaller than the product, and the flange reduction rate is made smaller than the web reduction rate in several successive passes from the first pass of the rough universal rolling. A method of rolling a narrow flange width H-section steel in which the flange width is increased to the product leg length by rolling with a larger size.
[0016]
(6) A method for rolling a narrow flange width H-section steel in which the rolling reduction is made at least 5% larger than the web rolling reduction.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 2 is an overall configuration diagram showing an example of a section steel rolling facility provided for the rolling method of Embodiment 1 of the present invention. In this section steel rolling equipment, the raw material slab that has exited from the heating furnace is first rolled by a breakdown rolling mill BD, which is a double rolling mill, into a shape suitable for the target product dimensions. In the rough universal rolling mill group including the rolling mill U and the edger rolling mill E, the thickness is reduced and the flange end is formed. Further, the flange is formed at a right angle by the finishing universal rolling mill F to obtain an H-shaped product.
[0018]
In the first embodiment, a slab having a rectangular cross section is used as a material, and a rough rolling of a shape suitable for a narrow flange width H-section steel is performed by a breakdown rolling mill BD provided with a pair of rolls having a pair of substantially H-shaped holes. Roll shaped slabs.
[0019]
FIGS. 1A and 1B are explanatory views showing rolling states by the breakdown rolling mill BD and the coarse universal rolling mill U in FIG. The raw steel slab 10 having a width substantially equal to the width of the die is rolled by one die 20 having a substantially H shape shown in FIG. At this time, as shown in FIG. 1A, only the hole-shaped web portion 11 of the raw steel slab is reduced, and the flange portion 12 passes between the rolls without being reduced. Although the flange portion 12 is stretched by stretching of the web portion and its thickness is reduced, the thickness is larger than that of the web portion 11, so that the cross-sectional shape of the raw steel slab approaches the H shape.
[0020]
As described above, the number of passes is greatly reduced by performing rolling with only one substantially die-shaped die 20 without reducing the short side of the slab except for adjusting the slab width. In the prior art, it was common to use a plurality of molds for rolling down the short side of the slab and perform rolling of two or more passes in each case. However, in the first embodiment by eliminating such a rolling pass, The number of passes can be reduced to less than half of the conventional method, and the rolling efficiency has been greatly improved.
[0021]
FIG. 3 is a characteristic diagram showing a change in the flange leg length HE in the breakdown rolling mill BD. When multi-pass rolling is performed with one substantially H-shaped hole die 20 as described above, the flange leg length HE, which is the distance between the web surface and the flange tip, increases as the number of rolling passes increases, as shown in FIG. However, the amount of increase gradually decreased, and it was found that the amount of saturation became saturated at a certain number of passes or more, and the amount of increase became zero. For this reason, when rolling down the breakdown rolling mill BD, it is preferable to perform rolling with a smaller number of passes than the number of passes at which the increase is saturated.
[0022]
FIG. 4 is a characteristic diagram showing a change in flange leg length HE when a raw steel slab rolled by a breakdown rolling mill BD is rolled by a rough universal rolling mill U. Before the increase of the flange leg length HE is saturated, or even if the roll is rolled in a substantially H-shaped hole form until it is substantially saturated, the flange leg HE of the crude steel slab at the end of rolling by the breakdown rolling mill BD is determined by the flange of the product. The leg length may be smaller than the leg length HEp, but in such a case, the length of the flange leg is increased by the subsequent coarse universal rolling mill U to make the dimension longer than the flange length of the product. In the rolling by the coarse universal rolling mill U, in order to effectively increase the flange leg length HE, rolling is performed under the condition that the flange draft is larger than the web draft, as shown in FIG. An increase can occur (after 6 passes).
[0023]
Here, in the rolling by the coarse universal rolling mill U, if the rolling reduction of the flange is made 5% or more larger than the rolling reduction of the web, the target flange leg length can be obtained with a small number of passes. The relationship of the draft is
Flange reduction rate ≥ Web reduction rate Desirably, flange reduction rate ≥ Web reduction rate + 5%
And Accordingly, in the coarse universal rolling mill U, as shown in FIG. 1B, the web portion 11 is relatively lightly reduced and the flange portion 12 is strongly reduced.
[0024]
In the first embodiment, rolling for increasing the flange leg length is performed in several passes from the first pass of the rolling of the rough universal rolling mill U. This is because, by increasing the flange leg length before the sheet thickness of the material to be rolled becomes thin, the material to be rolled stably passes between the rolls of the rough universal rolling mill U. Assuming that the path for increasing the flange leg length is other than the initial stage of the rolling of the rough universal rolling mill U, when a rolled material having a small flange leg length and a thin flange thickness passes between the rolls of the rolling mill, the flange falls down and the It is not preferable because an accident such as rolling between the sheets easily occurs.
[0025]
Embodiment 2. FIG.
By the way, it is ideal that the width of the slab to be the material is almost equal to the width of the die. However, there are many cases where the width of the material slab is actually cast every 100 mm, etc. In some cases, a slab wider than the width of the hole type is used instead of a suitable slab width. Embodiment 2 corresponds to such a case.
[0026]
FIG. 5 is an explanatory diagram of the rolling method according to the second embodiment. The short side of the slab 10 is reduced by using a pair of dies, preferably a concave dies 15 of the breakdown rolling mill BD, and the slab width is adjusted so that the width of the slab 10 becomes substantially equal to the width of the dies. . Subsequent processing is the same as in the first embodiment.
[0027]
【Example】
Embodiment 1 FIG.
Example 1 As a first example of the present invention, a narrow flange width H-section steel was rolled using the hot rolling equipment for section steel shown in FIG. Here, target product dimensions were a web height of 800 mm, a flange width of 100 mm, a web thickness of 10 mm, and a flange thickness of 18 mm. The dimensions of the material slab were 1000 mm in width and 250 mm in thickness. This slab was rolled for 7 passes with a substantially H-shaped hole die 20 having a hole width of 1020 mm and a web portion width of 764 mm to obtain a web thickness of 100 mm. A roughly H-shaped rough steel piece having a flange width of 170 mm and a flange thickness of 118 mm was obtained. Could be rolled. The rough billet is continuously rolled for a total of 12 passes by a rough universal rolling mill U and an edger rolling mill E, and finally is rolled for one pass by a finishing universal rolling mill F, whereby a narrow flange width H having a target size is obtained. The shape steel could be rolled.
[0028]
Embodiment 2. FIG.
Further, as a second embodiment of the present invention, a product having the same dimensions as in the first embodiment was rolled by using a raw slab having a width of 1050 mm and a thickness of 250 mm using the hot rolling equipment for shaped steel shown in FIG. 1. . First, the short side of the slab was reduced by a pair of concave molds 15 shown in FIG. 5 to make the slab width 1000 mm. Thereafter, by performing the same rolling as in Example 1, a product having a target size could be rolled. At this time, the number of passes of the breakdown rolling was 2 passes for the concave die 15 and 7 passes for the substantially H-shaped die 20 for a total of 9 passes.
[0029]
Embodiment 3 FIG.
Next, as a third embodiment of the present invention, using a hot rolling facility for shaped steel shown in FIG. 1, using a material slab having a width of 1100 mm and a thickness of 250 mm, a web height of 800 mm, a flange width of 200 mm, and a web thickness of A narrow flange width H-section steel having a flange thickness of 12 mm and a flange thickness of 18 mm was rolled. First, rolling was performed for 7 passes with a substantially H-shaped hole die 20, and when the web thickness was 100 mm, a roughly H-shaped rough steel slab having a flange width of 178 mm and a flange thickness of 156 mm was obtained. In the rolling in the seventh pass, the increase in the flange leg length was as small as about 1 mm, and it was expected that the increase in the flange leg length would be saturated in the next pass. Therefore, at this point, the rolling in the substantially H-shaped die 20 was completed, and the roll was conveyed to the rough universal rolling mill U. In performing the rough universal rolling, when the rolling was performed at a rolling reduction of about 5% higher than the web rolling reduction in the first five passes, the flange width increased to 250 mm. Thereafter, rolling is performed by a rough universal rolling mill U and an edger rolling mill E for 10 passes under the condition that the rolling reduction of the flange and the web is substantially equal in the rough universal rolling, and finally, one pass rolling is performed by the finishing universal rolling mill F to form an H-shape. When steel was used, a narrow flange width H-section steel having a target size could be rolled.
[0030]
Comparative Example 1
On the other hand, as a comparative example, as shown in FIG. 6, three dies for rolling the short side of the slab were used, and a product having the same dimensions was rolled by a method of rolling with a substantially H-shaped dies. The dimensions of the material slab were 1200 mm in width and 250 mm in thickness. The number of passes required for rolling the short side of the slab was 2 passes for the hole shape K-1, 4 passes for the hole shape K-2, 4 passes for the hole shape K-3, and 9 for the substantially H-shaped hole shape K-4. There were a total of 19 passes. The rough slab after the breakdown rolling was universally rolled in the same manner as in Example 1, and a product having desired dimensions was obtained in a total of 32 passes including the coarse universal rolling 12 passes, the finishing universal rolling 1 pass, and the breakdown rolling. . However, the number of rolling passes in the breakdown rolling was twice or more that of the method of the present invention, and the rolling efficiency was greatly reduced due to the large number of passes in the breakdown rolling.
[0031]
【The invention's effect】
As described above, according to the present invention, a narrow flange width H-section steel having a flange width of 1/4 to 1/10 of the web height can be rolled with high efficiency, and a great effect on reduction of manufacturing cost. Is obtained.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram illustrating an example of a section steel rolling facility provided for a rolling method according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a rolling state by a breakdown rolling mill BD and a rough universal rolling mill U of FIG. 1;
FIG. 3 is a characteristic diagram showing a change in flange leg length HE in a breakdown rolling mill BD.
FIG. 4 is a characteristic diagram showing a change in flange leg length HE when groove rolling is completed before the increase in flange leg length is saturated by breakdown rolling and universal rolling is performed.
FIG. 5 is an explanatory diagram showing a roll having a concave hole shape and a rolled state used in a rolling method according to a second embodiment of the present invention.
FIG. 6 is a schematic view showing a form of a prior art breakdown rolling mill.
[Explanation of symbols]
BD breakdown rolling mill, U rough universal rolling mill, E edger rolling mill,
F Finishing universal rolling mill.
10 Slab, 11 Web part, 12 Flange part, 15 Recessed hole type,
20 H-shaped hole type.

Claims (6)

A raw steel slab having a rectangular cross section is rolled into a roughly shaped steel slab by using a substantially H-shaped die, and the web and flange are reduced by a universal rolling mill, and the flange width is reduced by an edger rolling mill to achieve a target. A method for rolling an H-section steel having a narrow flange width, characterized by obtaining a product having a dimension as described below. 2. The method for rolling a narrow flange width H-section steel according to claim 1, wherein the raw steel slab is rolled without rolling when rolling into a crude steel slab by using one substantially H-shaped die. . After rolling the short side of the raw material slab having a rectangular cross-section with a pair of holes to adjust the width of the raw material slab, rolling the raw material slab with one approximately H-shaped hole into a coarse steel slab. The method for rolling an H-section steel having a narrow flange width according to claim 1, characterized in that: The method for rolling a narrow flange width H-section steel according to any one of claims 1 to 3, wherein rolling with one substantially H-shaped hole is completed before the increase in flange leg length is saturated. Rolling in one hole having a substantially H-shape is completed with the flange leg length smaller than the product, and the flange reduction rate is made larger than the web reduction rate in several passes from the first pass of the rough universal rolling. The method for rolling a narrow flange width H-section steel according to any one of claims 1 to 4, wherein the flange width is increased to a product leg length by rolling. 6. The method for rolling a narrow flange width H-section steel according to claim 5, wherein the rolling is performed with the flange reduction ratio being at least 5% larger than the web reduction ratio.

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