JPH05269501A - Method for rolling roughly shaped slab for h-shape steel with thick flange - Google Patents

Abstract

PURPOSE:To eliminate insufficient thickness in the inside of flanges at the time of roughly shaping a roughly shaped slab for a H-shape steel having ultrathick flanges using a continuously cast slab as a base stock by making the grooves of rolling roll into proper shapes. CONSTITUTION:The sectional shape of a double roll forming groove G40 which is brought into contact with the web and inside faces of flanges of a material to be rolled is formed into an approximately circular arc or poligon, the expansion (X direction) in the direction of web height is restrained by making an angle theta that is formed by the tangent of the section of groove at one half of the depth of groove and the vertical line so as to be in the relation of tan theta>=0.35 and the roughly shaped slab without insufficient thickness in the inside of the flanges is shaped. By using this roughly shaped slab, the product of the H-shape steel having the ultrathich flanges of which thickness is over 75mm can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an H-section steel, and more particularly to a method for rolling a rough-shaped billet in the production of an H-section steel having a super-thick flange from a slab cast by continuous casting.

[0002]

2. Description of the Related Art In recent years, as a material for rolled H-section steel, slabs cast by continuous casting (hereinafter referred to as CC slabs) have been frequently used from the viewpoint of process omission, energy saving, yield and quality stabilization. It was However, since the CC slab is originally a plate material and has a wide, thin and flat rectangular shape, there are many problems to be solved in forming an H-section steel having a large cross section from the CC slab, and various CCs are conventionally used. Has been proposed.

The H-section steel that can be produced from CC slabs in the present technology is up to a size called a so-called extra-thick H-section steel with a flange thickness of 30 mm or more and 75 mm or less, and an H-section steel with a flange thickness of more than 75 mm ( In the present invention, hereinafter, this is referred to as an ultra-thick H-section steel), it is said that molding from a CC slab is impossible.

A typical shaping means for producing a rough billet for H-section steel from a conventional CC slab is, for example, Japanese Patent Publication No. 58-37.
A rolling method called a wedge method or a berry method proposed in Japanese Patent Publication No. 042, Japanese Patent Publication No. 59-42563, etc. is well known. In this modeling method, triangular chevron portions P _{1 to} P ₃ are provided in the center of the bottom of the box cavities G1 to G3 engraved in the pair of upper and lower rolling rolls 1a and 1b shown in FIG.
Then, a concave groove is formed in the center of the slab in the thickness direction, and in the next hole type G2, width reduction is performed at the mountain portion to divide the flange corresponding portion and expand it into a dog bone shape, and then a box with a substantially flat hole type bottom. The recessed portion of the material is erased by the hole die G3, and then rolling is performed by the finish hole die G4 to form a required rough shaped steel piece.

The disadvantage of this rolling method is that when the finished material of the hole type G3 is rolled by the hole type G4 as shown in FIG.
It has been found from field experiments that a gap q is generated between the inner surface of the roll of No. 4 and the inner surface of the flange of the rolled material, and the hole-shaped G4 finished material has an excessively dented meat shortage on the inner side of the flange. .. In FIG. 7, the insufficient thickness width of the void q at the position of 1/2 of the die depth D from the die surface corresponding to the web surface of the rolled material to the die bottom corresponding to the flange tip of the rolled material. A has the relationship of the formula (2) with the reduction amount ΔH of the web thickness in the hole type G4.

[0006]

[Equation 1] In addition, the rough billet shape finished by this method is then rolled by a universal rolling mill, but in the case of ultra-thick H-section steel, the amount of reduction of the flange portion from rough rolling to finish universal rolling is the usual H type. Since it is smaller than steel, it has also been found that the aforementioned lack of meat inside the flange remains in the final product. In addition, as a result of the field test, if the total reduction amount ΔF of the flange portion from the rough-shaped steel slab to the final product and the meat shortage width A of the flange of the rough-shaped steel slab are within the range satisfying the formula (3), the meat is insufficient. Was found to be resolved. A / ΔF ≦ 0.05 (3)

In the case of producing a rough steel slab of ultra-thick H-section steel, the thickness ratios of the flange portion and the web portion of the rough steel slab are such that the stretch ratios to the final H-section steel product are almost equal. Need to be specified. This is because in the universal rolling process, when the stretch ratio of the web portion becomes larger than the stretch ratio of the flange portion per pass, the flange portion is reduced due to the stretch of the web portion, and various product defects such as meat shrinkage may occur. Will grow. Therefore, when the thickness of the slab, which is the material, is 250 to 280 mm, the flange thickness of the rough shaped steel slab obtained through the first and second steps of rough rolling is at most 1.
Since it is about 65 mm, and the web thickness of the rough steel slab corresponding to this flange thickness is about 100 to 120 mm, the hole type G
The reduction amount in No. 4 is from 130 mm to 180 mm, and the meat shortage width A is 4.5 mm or more from the above formula (2), and in order to eliminate this meat shortage A from the above formula (3), the universal rolling process is performed. The amount of reduction of the flange is required to be at least 90 mm or more. However, if the above-mentioned reduction amount for eliminating the meat shortage A is secured, a product with a flange thickness of at most 75 mm can be manufactured, and it is impossible to manufacture an ultra-thick H-section steel having a flange thickness larger than that. there were.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the shape of a roll hole die in a rough shaping step in a method for shaping a rough shaped billet for a super thick section steel using a CC slab. SUMMARY OF THE INVENTION It is an object of the present invention to provide a rolling method for a rough-shaped steel slab that solves the above-described conventional method, which eliminates the lack of meat inside the flange of the product.

[0009]

[Means and Actions for Solving the Problems] The gist of the present invention is as follows.
Double roll forming, following the first step in which the slab is cut in the width direction by a rolling roll having a plurality of box holes with a triangular chevron in the center of the bottom of the hole to sequentially widen the flange corresponding part of the H-section steel. A method of rolling a rough steel slab for H-section steel by a second step of finishing into a predetermined rough steel slab with a hole die, wherein the rolled material web and the flange inner surface side of the double roll forming hole die in the second step The cross-sectional shape of the part that comes into contact with is a substantially arc shape with a single or multiple curvatures,
It is formed into a polygonal shape having a plurality of corners or a shape in which a substantially arcuate shape and a polygonal shape are combined, and the tangent line of the hole die cross section and the vertical line at the hole die depth 1/2 of the forming die. A method for rolling a rough-shaped billet for a thick-walled flange H-section steel, which is formed into a shape having an angle θ formed by the following formula (1) and rolled: tan θ ≧ 0.35 (1) Further, Step 2 Double Roll Forming Multiple times of rolling with a hole die, the portion corresponding to the flange outer side of the H-section steel is rolled in the direction of reducing the web height, and the in-web normal dimension of the material to be rolled is set in the 2nd step double roll. The method is for rolling a rough-shaped billet for thick-walled flange H-section steel, which is made smaller than the lateral width dimension W of the web body of the forming hole die, and is then rolled again in the second step double roll forming hole die.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic view of a roll hole type used in the present invention. The box hole type G1 engraved on the pair of upper and lower rolling rolls 1a and 1b is a CC slab having a rectangular cross section, which is pressed down in the width direction to a width direction end portion. This is the first hole type for causing swelling and forming a dogbone-shaped intermediate rough shaped material. In the center of the bottom of the hole mold G1, a triangular mountain-shaped portion P ₁ formed by a gently sloping surface is provided so that the dog bone can be efficiently formed. The rolling roll pair having this hole type G1 is engraved integrally if the roll width of the roll pair of the breakdown mill sharing the box hole types G2 to G40 described later has a margin, but the existing CC slab sizing is performed. Of course, the width edging roll of the mill may be used as it is.

In the box hole molds G2 and G3, the flange-corresponding portion of the intermediate rough molding material roughly modeled by the box hole mold G1 is interrupted in the width direction by the triangular chevron portions P ₂ and P _{3 to} be expanded and reduced. The box hole type G4 is a finishing hole type, and is a hole type for finishing into a predetermined rough steel slab after forming with the hole type G3.

In the present invention, the step of expanding the flange-corresponding portion of the H-section steel by cutting the slab in the width direction by using the above-mentioned hole molds G1 to G3 is the first process, and the finishing hole mold G40 is performed after the first process. The step of finishing into a predetermined rough steel slab is called the second step. The feature of the present invention is that the portion Q in contact with the rolled material web of the groove G40 and the inner surface of the flange in the second step.
Is to specify the cross-sectional shape of and to finish-roll into a predetermined rough-shaped steel slab using this hole die.

FIG. 2 shows an example of the shape of the hole type G40 used in the method of the present invention, and FIG. 2 (a) is an arc in which the portion Q in contact with the web to be rolled and the inner surface of the flange is formed with one curvature. shape is a cross-sectional shape to Q _1, FIG. 2 (b) cross-sectional shape Q ₂ arc shape formed by a plurality of curvatures q ₁ to q _3,
In FIG. 2C, the nodes S _{1 to} S _n are connected by a straight line and have a polygonal cross-sectional shape Q ₃ or, as shown in FIG. 2D, an arc shape having the curvature q ₁ described above. Contact point S
A shape Q that combines a polygonal shape in which _{1 to} S ₃ are connected by a straight line
_{Use 4} .

Now, when the web of the material to be rolled is pressed down by the hole G40 having the hole shape as described above, FIG.
The amount of web reduction Δh shown in (a) and the spread ΔB of the web in the direction shown by arrow X can be expressed by equation (4). ΔB = C · Δh (4) Here, C is a constant and is known to be about 0.35. On the other hand, as shown in FIG. 3B, when the roll position is reduced from R ₁ indicated by the solid line to R ₂ indicated by the alternate long and short dash line, the positional change ΔW in the width direction of the roll surface due to the reduction is expressed by the equation (5). be able to. α is a value determined by the hole shape. ΔW = (tan θ · Δh / 2) + α (5)

Therefore, ΔW ≧ ΔB / 2, that is, ta
If nθ ≧ C−2α / Δh, the inner surface of the flange can be shaped by the hole-shaped side surface. That is, as shown in FIG. 4, the distance from the web pressing surface to the bottom of the die in the second step of contacting the web of the rolled material of the hole die G40 and the inner surface of the flange is D, and the position of 1 / 2D If the angle formed by the hole-shaped surface and the vertical line is at θ, the inner surface of the flange can be shaped if the relationship of equation (6) is satisfied. tan θ ≧ 0.35 (6) If the value of tan θ is less than 0.35, the amount of spread in the web height direction becomes large and it becomes difficult to form the inner surface of the flange. That is, by defining the tan θ of the hole shape G40 in the second step, it is possible to suppress the generation of voids between the roll and the material to be rolled.

Further, in order to reliably produce a rough-shaped steel slab without a lack of meat, it is necessary to suppress the generation of voids to a small amount. To this end, edging rolling is performed with the groove G3 shown in FIG. 1 in the course of rolling a plurality of times with the hole G40, and the groove G4 shown in FIG.
Assuming that the distance between two hole bottoms of 0 is W and the distance between the inner ends of the left and right flanges of the rolled material is S, the web height of the rolled material and the in-web method are calculated so as to satisfy the relationship of equation (7). The web of the material to be rolled and the portion corresponding to the inner side of the flange can be finished into a shape along the roll hole die by reducing the size and then performing finish rolling again with the hole die G40. W ≧ S (7)

[0017]

According to the present invention, as compared with the case where the conventional hole type G4 is used, the metal flow in the web height direction of the portion corresponding to the web is suppressed, and the thickness of the flange can be sufficiently secured. Became. Further, even in the edging rolling in the second step, conventionally, only the rolling up to the shaping rolling (so-called edge rolling) of the protruding portion on the outer side of the flange was possible, while the large rolling edging rolling was performed. After that, it became possible to roll the web while widening the inside of the flange with the hole type G40. At this time, the material to be rolled can be shaped not only on the outside of the flange but also on the inside of the flange, and the inside of the flange can have a shape that conforms to the roll hole die, and it is possible to supply rough-shaped steel slabs inside the flange without lack of thickness. ,
CC thick flange H-section steel with flange thickness exceeding 75 mm
It has become possible to easily manufacture from a slab.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rolling roll hole die for carrying out the present invention.

2 (a) to (d) are schematic cross-sectional views of a roll hole type showing an example of the hole type G4 in FIG.

FIG. 3 (a) is a sectional view of a hole type for explaining the present invention, and FIG. 3 (b).
[Fig. 4] is a partially enlarged view of a portion S in (a).

FIG. 4 is a detailed explanatory view of a hole type G4.

FIG. 5 is an explanatory view showing rolling conditions of the hole G3 and the hole G4 in the present invention.

FIG. 6 is a schematic cross-sectional view of a conventional rolling roll hole type.

FIG. 7 is a schematic view showing a lack of meat inside the flange portion that occurs in the hole type G4.

[Explanation of symbols]

1a, 1b vertically rolling rolls G1~G4 according to the caliber G40 present invention finishing grooved P ₁ to P ₃ chevrons q gaps A meat insufficient width

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Nakatsuji 1 No. 1 Tsukiko Hachimancho, Sakai City, Osaka Prefecture Nippon Steel Corporation Sakai Steel Works Co., Ltd.

Claims (2)

[Claims] 1. A first step of successively expanding the flange corresponding portion of the H-section steel by cutting the slab in the width direction by a rolling roll having a plurality of box cavities each having a triangular chevron at the center of the bottom of the cavities. A method of rolling a rough billet for an H-section steel by a second step of finishing a predetermined rough billet with a double roll shaping punch, wherein a rolled material of the double roll shaping punch of the second step Form the cross-sectional shape of the part that contacts the web and the inner surface of the flange into a substantially arcuate shape with a single or multiple curvatures, a polygonal shape with a plurality of corners, or a combined shape of the substantially arcuate shape and the polygonal shape. At the same time, the forming die is formed into a shape having an angle θ formed by a tangent line of the die cross section and a vertical line at a die depth of 1/2 and having a relationship of the following formula (1), and rolling is performed. Thick flange for rough steel billet for H-section steel Extension method. tan θ ≧ 0.35 (1) 2. The second step, in the course of multiple rolling by means of a double roll forming die, the portion corresponding to the outside of the flange of the H-section steel is rolled in the direction of reducing the web height, and the in-web normal dimension of the rolled material is set. The thickness according to claim 1, wherein after the width of the web body portion of the second step double roll forming hole die is made smaller than W, the rolling is performed again by the second step double roll forming hole die. Rolling method for rough-shaped billet for thick flange H-section steel.