JPH0199701A - Method for rough rolling h shape - Google Patents

Abstract

PURPOSE:To manufacture large size H shape from a thin slab with high efficiency at a low cost by forming a V-shape notch in the central part of a flange of a beam blank formed by rolling a slab stock and opening and flattening the notch. CONSTITUTION:A stock slab 1 is rolled by drafting the web of the slab by use of caliber so that a beam blank 11 whose web 11-2 is thined is formed. Then, a V-shaped notch 12 having a depth (l) determined by (l)>=0.6X{B/2-(T-S)} is formed at both the edge face center of a flange part 11-1 of the blank 11. (In the equation, (l): depth of a V-shaped notch, mm, B: flange width of H shape product, mm, T: width of flange part 11-1, mm, S: thickness of web 11-2, mm). Next, the notch 12 is pressed and opened by caliber to obtain a beam blank 14 having a recess part 13 with a large flange width; then, a beam blank 15 is formed by opening and flattening the recess part 13. The beam blank 15 is finishing rolled to obtain an H shape whose flange width is wider than that of the rough slab stock.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for rough rolling H-section steel, and more particularly, to a method capable of producing H-section steel having a larger dimension than a narrow rough-section steel piece with high efficiency and at low cost.

[Conventional technology]

In recent years, from the viewpoint of energy saving and yield, it has become common to roll H-beams from continuously cast slabs. In other words, in the conventional general manufacturing process, continuously cast rough-shaped steel pieces (slabs, beam blanks) are heated through a heating process.
H-section steel is manufactured through a rough rolling process, an intermediate rolling process, an etching process, and a finishing rolling process. However, in this H-beam manufacturing method, a rough-shape steel piece is rolled into a dogbone shape in the rough rolling process, so a very large rolling reduction is required in the case of a wide H-shape steel. For this reason, a large fishtail occurs at the leading and trailing ends of the rough-shaped steel piece, and the amount of crop cut-off after rough rolling becomes large, leading to a decrease in rolling yield. Further, since rolling in the width direction requires a considerable number of passes, there is a problem in that the rolling efficiency is also significantly reduced. Therefore, as a way to solve the above problem,
Publication No. 18124 describes a bond in which V-shaped splits (2) are made on both side end faces of a rough-shaped steel slab (1), and the splits are made deeper in order, as shown in Figure 3, and a bond is created in which the splits are expanded to form a beam. A method of forming a blank (3) is disclosed. According to this method, large fishtails do not occur at the front and rear ends of the rough-shaped steel billet, so the yield is improved, the flange width width is improved, the number of rolling buses can be reduced, and the rolling efficiency is improved. Even when manufacturing a large-sized H-beam from a thin flat steel piece, it is possible to manufacture it by heating only once. [Problems with Prior Art] However, the conventional method of forming a beam blank by inserting the above-mentioned cracks has the following problems. In the case of large-sized H-section steel, the slab is erected in the rough rolling process and both ends are pushed apart by strong width reduction to form a beam blank, so the required slab width is very large. For example, @900mmX300
When rolling mm, the slab width is at least 1300m
m or more is required. For this reason, there was a problem that the number of rough rolling passes increased. That is, in the web rolling process performed after the splits placed in the centers of both end faces of the slab are pushed open, the width of the flange 2 is significantly reduced as the web is rolled down. This is because the volume of the flange is small compared to the volume of the web being rolled down, so metal flows from the flange to the web. For this reason, it is necessary to compensate for the flange width due to web reduction, and the slab width has to be increased.
The depth of the glyph divisions also inevitably becomes deeper. Therefore, the number of rough rolling passes increases. Furthermore, as the width of the slab increases, the number of slabs accommodated in the heating furnace decreases, and the heating efficiency also decreases. That is, when the number of furnaces is small, the heating efficiency decreases because the slab thickness is thin. Therefore, the rolling efficiency of large-sized H-beams from wide slabs is extremely low even though the unit weight of other small- and medium-sized H-beam products is greater. This invention was made in order to solve the problems of an increase in the number of rough rolling baths and a decrease in heating efficiency in the conventional manufacturing method of H-beam steel with V-shaped splits. The purpose of the present invention is to propose a rough rolling method that can produce thin continuous cast slabs or rough shaped steel slabs with higher efficiency and lower cost. (Means for Solving the Problems) The present invention involves rolling a slab of material or a continuously cast rough beam blank to form a beam blank with a thinner wear in the rough rolling process of H-section steel. By inserting a V-shaped split with a depth of 2 determined by the formula below from both sides in the center of the flange end face, and then pushing the V-shaped split open and flattening it, a beam with a width of both side flanges larger than that of the rough shaped steel piece is created. It is characterized by forming a blank. A≧0.6 (B/2-(T-3))...
(1) 2: Depth of V-shaped split (mJ) B: 7-lunge width of H-shaped steel product (mm) T: Flange width of beam blank into which V-shaped split is placed (mm) S: Beam blank into which V-shaped split is placed web thickness (mm > In other words, in the process of rough rolling an H-section steel with a larger size than a rough-shaped steel slab, the present invention performs wear rolling directly from the rough-shaped steel slab, and then creates a V-shaped split in the 7 flange portions of both the contacting sides. This is a method to obtain a flange width larger than that of the rough-shaped steel slab by inserting the H-shaped steel slab into the rough-shaped steel slab. Etching rolling (width reduction of slab or beam blank) (B) Shape rolling (web thickness reduction) The conventional process shown in Fig. 3 is (A>■Blank rolling - (B)
) It was shape rolling. In the case of this method, since the width reduction effect of the 7-lunge in shaping rolling is large, the amount of edging becomes large, and a rough-shaped steel billet with a large number of edge buses and a wide width is required. Therefore, in this invention, the order of (A>Edging rolling and (B) Shaping rolling is reversed, so that (B) Shaping rolling-(A>Edging rolling). Figure 1 shows the rough rolling process of this invention. It is a schematic diagram.Here, explanation will be given taking a slab as an example.That is, in this invention, as the first step of rough rolling, a beam blank (11) with a thin web thickness is formed by subjecting the slab (10) to web rolling using a groove die. When the web is rolled down directly from the slab, the volume of the web (11-2) and the flange portion (11-2) are reduced because the width of the slab is not reduced.
There is no big difference in the volume of 1), and the decrease in flange width due to web rolling is extremely small. In addition, the beam blank (
The web thickness in 11) is preferably made as thin as possible within a range that does not buckle when the V-shaped sides inserted into the flange portion in the subsequent process are expanded. For example, in the case of a slab whose material width is approximately 400 to 500 mm larger than the web height of the H-beam product, the width must be at least 150 mm or less. That is, if a beam blank having a web thickness of 150 mm or more is intermediate rolled in the universal mill group, the number of passes in the universal mill group increases and productivity decreases. Next, the beam blank (11) obtained by shape rolling
On the other hand, the above-mentioned (1
) Insert a V-shaped divider (12) with a depth of 2 determined by the formula. This V-shaped split is achieved by turning the beam blank (11) through 90 degrees and using a split hole with an apex angle of about 60 degrees in the center of the hole. The depth of the V-shaped split is defined as the depth l determined by equation (1) above, which was derived from the results of many experiments by this inventor, and the depth l that satisfies this condition is It has been found that the effect of increasing the flange width is greatest by adding this. Next, a beam blank (14) with a concave portion (13) having a large flange width is created by expanding the V-shaped split (12) with a split hole mold having the same apex angle as above but with an arcuate tip. form. Next, the recesses (13) of the recessed beam blank (14) are erased and flattened using a box hole mold having a flat hole shape to obtain a beam blank (15). The effect of widening the flange portion in this process is the same as that of the conventional method. However, since the present invention does not include a shaping rolling process in which the web is rolled down after the edging rolling, the width of the flange can be increased by about 172mm compared to the conventional method. In other words, the amount of etching is only about 172. Therefore, the required slab width can be reduced by 200 mm or more compared to the conventional method. For example, H400+nmX 400+++m with thickness 25
When manufacturing from a 0 mm slab by the conventional method, the above (
In formula 1), ding = S - 250mm. In other words, in the case of direct slab etching, 2≧120+++m. On the other hand, in the case of the method of the present invention, a slab having a thickness of 250 mm is rolled to a web thickness of 120 rnTrl by shape-hole rolling. The flange width at this time is still 230 mm. In other words, (230mm>-3(120mm) = 110m
m, and 2≧54 mm, which is 50% or less compared to the conventional 2. Therefore, the slab width can be reduced by 100 to 200 mm, and the number of rough rolling passes can be reduced by 20% or more. In the case of this invention, since the vertical and horizontal symmetry of the flange portion of the beam blank is obtained after etching, the uniformity may be slightly inferior. For this reason, it is preferable to carry out finishing rolling in one pass in which the flange shape is made uniform without substantially rolling down the web. Furthermore, if the universal mill group has the capacity, it is also possible to carry out only shape rolling for web rolling and V-shaped splitting rolling in the rough rolling, and to widen the V-shaped splitting with the universal mill group. [Example] A 1-1700×300 H-section steel was manufactured by the manufacturing process having the layout shown in FIG. In Figure 2, (2
0) is a heating furnace, (21) is a reversible double rough rolling mill, (22
) shows the universal rough rolling mill II, (23) shows the double shaping rolling mill, (24) shows the universal finishing rolling mill, and (25) shows the crop saw, respectively. A continuous cast slab with material dimensions of 250 mm thick x 1200 mm wide is heated to 1250°C in a heating furnace (20), and then reversible double rough rolling II (21) is performed to create a flange thickness that is approximately the same as the conventional forming hole type and approximately A dogbone-shaped beam blank with a web thickness of 82 mm and a flange width of 240 n++r+ was obtained using a forming hole mold with a thickness of approximately 100 w+m in 14 baths.Then, a beam blank with a depth of 90 mIr1 was obtained using an edging hole mold for cutting with an apex angle of 60 degrees. A V-shaped split was made in two passes.The flange width at this time was about 240 mm, the same as after shape rolling.Next, two passes were rolled using an edging hole mold with an arcuate tip, and the flange was rolled in two passes. Width from 240mm to 320m
The depth of the V-shaped split was 60 mm, making it shallow and smooth. After that, the flange width was changed from 320mm to 365mm by 2-pass rolling using a box hole die.
mm, and the depth of the V-shaped split was reduced to 20 mm.Finally, one pass of rolling was performed in a finishing hole die to flatten the flange end face, and rough rolling was completed in a total of 21 passes. In addition, the web reduction in rolling with the finishing hole die was only a few M. On the other hand, in the conventional method, the material size is 2501 TIm thickness x 1
A slab with a width of 400 mm is required, and a V with a depth of 12,011 m (depth of 90 mm in the present invention) is formed on both end faces of this slab.
Insert the glyph split and edge this to make the flange width 54
A beam blank of 0 mm was formed. In order to form this final beam blank, the conventional method uses initial etching 1.
Rough rolling was completed in a total of 29 passes: 1 pass and 18 passes for shaping and tentering. Therefore, compared to the method of the present invention, the conventional method increases the flange width by 29 On++n by etching, whereas the method of the present invention increases the flange width from 240 mm to 365 mm.
All you need to do is increase it by 125mm. This is because in the conventional method, the flange width decreases significantly due to web reduction during shaping rolling, which reduces the effect of increasing flange width during slab etching, whereas in the method of the present invention, the flange width decreases due to web reduction. This is because the effect of increasing the flange width is large because the amount is very small. [Effects of the Invention] As explained above, according to the method of the present invention, the amount of decrease in the flange width due to web rolling in shaping rolling is small, and the flange width in the edging rolling process can be increased, so that narrow-width rough-shaped steel pieces can be Larger sized H-section steel can be efficiently rolled and produced with fewer passes. In addition, the width of the slab can be reduced (and the number of slabs that can be accommodated in the heating furnace can be increased), which improves productivity and lowers costs by increasing heating efficiency. It has a great effect on the production of H-type steel.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the rough rolling process of the present invention. FIG. 2 is a schematic diagram showing the equipment layout in an embodiment of the present invention. FIG. 3 is a schematic diagram showing a conventional rough rolling process. 10... Slab 11... Beam blank 11 obtained by shape rolling
-1...Flange part 11-2...Web 1
2...V-shaped split applicant Sumitomo Metal Industries, Ltd. Figure 2 I 2 2 3

Claims (1)

[Claims] In the rough rolling process of H-beam steel, after rolling a slab of material or a continuously cast rough beam blank to form a beam blank with a thinner web, the center of the flange end face of the beam blank is rolled from both sides. Depth l determined by the following formula
A beam blank having a width of both side flanges larger than that of the rough-shaped steel piece is formed by inserting a V-shaped split, and then pushing the V-shaped split open and flattening it.
Rough rolling method for section steel. l ≧0.6 Flange width (
mm) S: Web thickness of the beam blank into which the V-shaped split is inserted (mm)
m)