JP3617085B2 - Coarse slab rolling method for wide thick H-section steel - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for rolling a rough slab of H-section steel having a wide flange width and a thick wall made of a continuously cast slab.
[0002]
[Prior art]
In general, large H-section steel is rolled by an ingot-rolling method (see, for example, JP-A-53-57167) in which an ingot is formed into an H-shaped rough section, or from a flat slab to an H-shaped rough section. There is a slab width rolling method for forming (see, for example, Japanese Patent Laid-Open Nos. 55-70402, 56-95402, and 60-21101).
[0003]
By the way, if the H-shaped steel has a wide flange width and a thick cross section, for example, in the case of a thick wall size of H500 × 500 or H400 × 400 due to the width limitation from the flat slab and the thickness restriction of the dogbone, the split rolling method. Is a general rolling method.
[0004]
[Problems to be solved by the invention]
However, as described above, in the conventional method, since the wide and thick H-shaped steel is manufactured by using the ingot-making material by the ingot rolling method, from the aspect of cost reduction such as stable quality or improved yield. Continuous casting was desired.
However, when trying to obtain a rough H section for large H-section steel from a conventional flat slab made of continuous casting, a factor that restricts the width of the dogbone that is generated due to the slab end pressure reduction. As
(1) In order to suppress the extension in the rolling direction and make it wider, the spreading efficiency decreases as the spread increases, and the desired width cannot be achieved.
(2) Although the spread occurs when the height is reduced, the material collapses and the symmetry of the shape collapses as the height reduction proceeds.
Etc.
[0005]
In addition, regarding the flange thickness, the thickness near the tip of the dogbone shape is thin and the root is thick, so it is difficult to ensure the thickness near the tip of the H-shaped steel after sizing.
An object of the present invention is to provide a rough slab rolling method when rolling a wide and thick H-section steel using a continuous cast slab that solves the problems of the prior art as described above. .
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention effectively utilizes the phenomenon that the inclination angle of the flange inner surface is raised when the web is stretched by reducing the web height, thereby improving the width-curing efficiency and the flange tip by reducing the leg length. This is a combination of increasing the thickness of the part and finishing to an H-shaped rough cross-section with a small thickness difference of the flange.
[0007]
That is, the end of a continuous cast slab is widened to form a dogbone shape, then sizing into an H-shaped rough cross section by rough rolling, and a wide thick wall having a predetermined web thickness, flange thickness and width by a universal rolling mill In the rough rolling process when forming and rolling into H-section steel, first, the flange leg length is obtained by perforating rolling in which the flange inner surface inclination θ is increased to the same degree as the dogbone inclination. Next, the second step of rolling down the web height direction a plurality of times while causing the flange inner surface inclination, and forming the material into a rough cross-sectional shape for flange wide H-shaped steel. The third step, and the fourth step of raising the inner surface by rolling down in the web height direction and the same width as in the second step, and then performing flange leg length reduction rolling to produce the flange End thickness is the fifth step, wide thick rough shaped steel strip rolling method meat H-beams, characterized in that it consists of performing the hole molding rolled to thickness increasing as approaching the base thickness.
[0008]
[Operation]
According to the present invention, the reduction in the web height direction is carried out in three steps, so that the restriction of collapse is reduced, the ratio of the slab width / thickness is increased, and the maximum manufacturable flange width is increased. can do. In addition, when roughly forming the web height and flange width into a series that is slightly smaller, the tip corner is thickened so that the difference between the tip of the flange thickness and the base is reduced, so that the tip corner at the next universal rolling is reduced. It becomes easy to satisfy, and the maximum flange thickness that can be manufactured can be increased.
[0009]
Hereinafter, the operation of each step will be described in detail with reference to FIG.
(1) Effect of rough forming: For the purpose of forming all the dog bones at the end of the slab into a flange cross section, as shown in FIG. In the first pass, the dogbone shape is left unconditionally (FIG. 1 (b)). Further, the inclination θ of the inner surface of the flange makes it easy for a portion that is not reduced when the web is reduced to remain as a root portion of the flange. The inclination θ at this time is an angle close to the shape of the dogbone, that is, 20 to 30 °.
(2) Action during web height reduction: As shown in FIG. 1 (c), an angle of Δθ in which the amount of cross-sectional movement differs between the portion a receiving the reaction force caused by the web and the portion b receiving the reaction force is small. A change and a width change of ΔB occur.
(3) As shown in FIG. 1 (d), when the angle θ of the inner surface decreases and the flange width D increases, the widest flange width that can be produced is obtained by sizing the flange shape close to that shape.
(4) In order to increase the flange tip thickness, further reduction is applied in the web height direction, causing the angle and width to change by the same action as in step (2).
(5) Flange tip thickening action: If the shape of the hole shape is reduced as shown in Fig. 1 (e) and the leg length is pressed down, pressing the c section will fill the d section of the gap in the c section where the location is limited by metal flow. The thickness is increased and there is almost no difference in thickness from the flange base.
(6) Since the thickness reduction of the flange tip is obtained from the first pass as shown in FIG. 1 (f) in the rough universal rolling mill, non-contact due to the roll angle and material angle difference as shown in FIG. 1 (g). There is no problem that the portion does not easily satisfy the extension of the rolled material, and the corner of the flange tip portion can be easily shaped.
[0010]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a schematic diagram showing the arrangement of rolling mills to which the method of the present invention is applied. In the figure, 1 is a soaking furnace, 2 is a batch rolling mill, 3 is a continuous heating furnace, 4 is a breakdown rolling mill, 5 is a down cut saw, 6 is a rough universal rolling mill, 7 is an edger rolling mill, and 8 is Finishing universal rolling mill.
[0011]
First, for example, a continuous casting slab 10 having a thickness of 310 mm × width of 1800 mm is heated to 1250 ° C. to 1300 ° C. in the soaking furnace 1 and is subjected to rough forming rolling by the block mill 2. The segment roll 2a used in the segment mill 2 is a No. 2 shown in FIG. 1-No. 4, the continuous cast slab 10 shown in FIG. 1 is provided with a belly groove A as shown in FIG. 2 to widen the belly groove A to the guide as shown in (c) to form a dogbone B. No. 3 is used to carry out the stepping out as shown in (d) through several passes step by step. 4 is used to perform rough forming of the rough rolled material 11 shown in (e).
[0012]
Hole type No. In the rough forming process according to No. 4, the web thickness is reduced to increase the inclination angle θ of the flange portion to increase the degree of filling. Returning to step 3, a pass for edge shaping edging is performed, and the sheet is rolled to a predetermined web thickness. In this case, the hole type No. 4 width: H ₄ is a hole type No. of a breakdown roll 4a in FIG. Width 5: H ₅ (= 800 mm) is widened by the amount of height reduction in the next process, but considering the occurrence of tilting and twisting,
H ₄ ≈H ₅ + (Web thickness of hole type No. 4) −990 mm
Then, rolling is possible without problems.
[0013]
At this stage, the rough rolled material 11 is once cooled, and after steel piece care such as scraping and cutting the defective portion of the leading end, it is again heated to 1250 ° C to 1300 ° C in the continuous heating furnace 3, In the breakdown rolling mill 4, the No. 1 shown in FIG. 5-No. 7 is sequentially rolled using a breakdown roll 4a having three hole types.
First, the web height of the rough rolled material 11 is set to the hole type No. 6, as shown in FIG. 5 _Width: multiple paths rolled up slightly smaller width for example 760～ 770 mm than H 5 (= 800 mm) put are as _{H 5.} In this rolling, as shown in FIG. 1 (c), the phase shift of the inner surface shape of the flange b having a small rolling reaction force is different, and the flange inner surface angle occurs by Δθ. In an extreme case, the part a hardly changes, and the part b changes the position of the amount close to Δw, so that the flange inner surface is raised by the angle Δθ.
[0014]
Next, the punched No. 1 was designed so as to leave the leg length as much as possible for the rough rolled material 11 which was raised at an angle and flanged. Rolled with 5 to shape the shape of the flange.
As a result, the leg length L shown in FIG. 1 (d) is 225 mm, for example, and the flange thickness D is 115 mm, for example. Therefore, this is sent to the universal rolling mill groups 6 to 8 for universal rolling. Thus, it becomes possible to roll-form H-section steel having a flange thickness of 90 mm in the H500 × 500 series.
[0015]
In addition, the hole type No. 5, the rough rolled material 11 sized to the maximum flange width size as shown in FIG. No. 6 was used to perform flange inner surface angle raising and flange width rolling by reduction in the web height direction shown in FIG. The leg length is reduced by 7 and the rough H-section material 12 with the increased thickness at the flange tip as shown in FIG. 5D is rolled. At this time, as shown in FIG. 1 (e), the c portion at the tip indented portion is deformed so that the hole-shaped gap d portion is filled by the metal fluctuation due to the reduction.
[0016]
By this method, the difference in the thickness D of the flange of the rolled rough H-section material 12 can be reduced between the tip portion and the web root portion. This has the effect that a parallel flange shape can be achieved at an early stage of universal rolling as shown in FIG. 1 (f), and the flange tip as shown in FIG. The ratio of the maximum flange thickness that can be made to the product with respect to the thickness of the coarse H-section material 12 can be increased as compared to the case where the contact with the roll is delayed due to the extension of the portion. Thereby, in the Example of this invention, it becomes possible to roll-form to flange thickness 150mm by H400 * 400 series.
[0017]
【The invention's effect】
As described above, according to the present invention, when rolling H-section steel from a continuous cast slab, the technology for increasing the width spreading efficiency and the technology for increasing the thickness of the dogbone are combined. It is possible to produce a thick H-section steel.
In addition, by rationally combining the flange width and web height, the wide width H500 × 500 series and H400 × 400 (H14 ″ × 16 ″) series that are currently rolled in Japan are made of the same material. There is also an effect that it is possible to manufacture the same lump roll and breakdown roll.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the operation of the present invention.
FIG. 2 is a schematic diagram showing the arrangement of rolling mills to which the method of the present invention is applied.
FIG. 3 is a partial front view showing (a) a lump roll and (b) a breakdown roll used for carrying out the method of the present invention.
FIG. 4 is an explanatory view showing a rolling process with a split roll of the method of the present invention.
FIG. 5 is an explanatory diagram showing a rolling process with a breakdown roll according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Soaking furnace 2 Split mill 2a Split roll 3 Continuous heating furnace 4 Breakdown rolling mill 4a Breakdown roll 5 Down cut saw 6 Rough universal rolling mill 7 Edger rolling mill 8 Finish universal rolling mill 10 Continuous casting slab 11 Rough rolled material 12 Rough H section material

Claims (1)

After widening the end of the continuous cast slab into a dogbone shape, sizing it into an H-shaped rough section by rough rolling, and using a universal rolling mill, a wide and thick H-shape with a predetermined web thickness, flange thickness and width In the rough rolling process when forming and rolling steel,
First, the first step of adjusting the flanges at four locations by taking out the flange leg length by perforating rolling in which the flange inner surface inclination θ is increased to the same degree as the dogbone inclination,
Next, a second step of performing width-developing while causing the flange inner surface to be inclined by reducing the web height direction a plurality of times,
A third step in which the material is molded and die-rolled into a rough cross-sectional shape for flange wide H-section steel;
Further, through the fourth step of raising the inner surface and reducing the width by the reduction in the web height direction as in the second step,
Then, the fifth step of performing the hole forming and rolling to increase the thickness so that the flange tip thickness approaches the root thickness by performing flange leg length reduction rolling,
A method for rolling a rough shaped steel slab of a wide thick H-shaped steel.

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