JPH07148504A - Method for increasing inner width of web of wide flange shape - Google Patents

Abstract

PURPOSE:To easily and correctly bite a rolled stock in a finishing universal mill by extending the tip of the rolled stock in the fan-shaped manner in executing the rolling by a universal roughing mill. CONSTITUTION:In a method for increasing the inner width of the web by setting the horizontal roll width of a universal finishing mill 7 to be wider than that of a universal roughing mill 5 after a rolled stock 8 is successively rolled by a break-down mill 2 and the universal roughing mill 5, the tip of the rolled stock 8 is cut and aligned so that the whole sections of the flange and web may be the cutting section before executing the rolling by the universal roughing mill 5 after executing the rolling by the break-down mill. Rolling is executed under the condition where the total draft before the final rolling pass of the universal roughing mill 5 in the following process satisfies the inequality of (draft of flange)>(draft of web), and the total draft at the final rolling pass satisfies the inequality of (draft of web)>(draft of flange).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for hot-rolling the height of a H-section steel web in a size-free manner, and more particularly to a method for widening the inner width of the web.

[0002]

2. Description of the Related Art As a method for rolling the web height of H-section steel in a size-free manner, a reduction rolling method using vertical rolls of a finish universal rolling machine and a method of widening the inner width of the web during or after rough universal rolling are used. A method is generally known in which after widening with a dedicated mill, finish rolling is performed. On the other hand, as another technique of these, there is also a technique of widening the web by a finish universal rolling mill, which is disclosed in JP-A-60-1183.
No. 01, JP-A-58-135705, JP-A-3-258401 and the like. Therefore,
An example of a rolling mill train in which web widening is performed by a finishing u universal mill is shown in FIG. 2, and an example of generally manufacturing H-section steel will be described below based on FIGS. 2 to 5.

First, in the heating furnace 1, 1250 ° C. to 13 ° C.
The rolling material (normally H-shaped rough billet or continuous casting slab) heated and soaked at 20 ° C is H-shaped with the cross section shown in Fig. 3 (a) by the breakdown mill (rough rolling mill) 2. Coarse sized. At that time, as shown in FIG. 4 (a), the crop shape of the front and tail ends of the rolling material 8 causes a difference in extension between the web and the flange, and generally, the web portion having a large reduction rate during rough rolling extends to form a tongue. It becomes the shape called (tongue). And this tongue is usually a tongue
Is cut at the positions indicated by AA and CC in FIG. Subsequently, the H-shaped rough rolling material 8 from which the tongue has been cut and removed is sent to the rough universal mill 5 and the edger mill 6 in the next step, and reciprocal rolling is performed a plurality of times between both mills. After finishing, Universal Mill 7
Where it is finally formed and rolled into an H-section steel. At that time, as the upper and lower horizontal rolls 7a and 7b of the finish universal mill 7, rolls of variable width are used.
The inner width W ₂ of the web can be freely changed as shown in FIG.

However, when the above-described tongue cutting method is adopted and the rolling material 8 is rolled by the conventional rough universal mill, the following problems occur. That is, as shown in FIG. 5A, since the horizontal roll width W ₂ of the finishing universal mill 7 is set wider than the roll width W ₁ of the rough universal mill 5, the bending of the tip of the material and the inside of the web Narrowing often occurs. In addition,
FIG. 5A is a plan view, in which the horizontal rolls 7a and 7b are drawn by dotted lines and the vertical rolls 7c and 7d are drawn by solid lines. In the finishing universal mill 7, the n-part of the web tang (Fig.
(See (a)), but the horizontal rolls 7a, 7
In the state of being pressed down by b and being unable to move in the height direction of the web, the flange tip m portion (see FIG. 5A) is caught in the web-corresponding portion of the horizontal rolls 7a and 7b (FIG. 5A). (See), there were often troubles that made rolling impossible. This is the shape of the tip of the rolled material (tongue)
Is a non-steady region, and there is local deformation such as material bending, left / right flange extension length differences, and cracks. Therefore, a material with an H-shaped cross-section is a finishing universal mill with a wider horizontal roll. This is because it is difficult to correctly lead to 7.

[0005]

In view of the above situation, the present invention uses a horizontal roll having a wider width by expanding the H-shaped cross-sectional shape of the leading end of the material to be rolled into a fan shape when rolling in a coarse universal mill. It is an object of the present invention to provide a method for widening the inner width of an H-section steel web that allows a rolled material to be easily and properly bitten into a finishing universal mill.

[0006]

Means for Solving the Problems The inventor has conducted extensive studies to achieve the above object and obtained the following findings. A general universal mill for H-shaped steel rolling has a structure in which driven horizontal rolls and vertical left and right rolls which are not driven are positioned substantially coaxially. The rolling material has a reduction rate difference between its web portion and flange portion. It deforms after rolling due to the difference in the extension length of the tip portion, and in particular, the shape when the tip portion of the rolled material 8 comes out of the mill changes variously. The present invention has been made in view of effectively utilizing this deforming property.

That is, according to the present invention, after rolling a rolling material in sequence with a breakdown mill and a rough universal mill, the horizontal roll width of the finishing universal mill is set wider than the horizontal roll width of the rough universal mill. In the method for widening the inner width of the H-section steel web described above, the flange and the entire cross section of the web become cut surfaces before the rolling of the tip end of the above-mentioned rolling material in the rough universal mill after rolling in the breakdown mill. Cut and align, coarse universal in the next process
The total rolling reduction before the final rolling pass of the mill is (flange rolling reduction)> (web rolling reduction), and in the final rolling pass of the rough universal mill, (web rolling reduction)> (flange rolling reduction) It is a method for widening the inner width of the H-section steel web, which is characterized in that Further, in order to promote the effect, the present invention, during rolling in a breakdown mill,
The method for widening the inner width of an H-section steel web according to claim 1, wherein the web thickness is made thinner than only the rearmost portion of the rolled material.

[0008]

According to the present invention, the unevenness of the leading end of the rolling material caused by rough rolling in the breakdown mill is trimmed to reduce the amount of flange reduction until the final rolling pass of the rough universal mill in the next process. Since the rolling is made larger than the amount, the flange has a so-called negative tongue shape (see FIG. 6A) extending from the web. In addition, in the present invention, a rolled material having a tip of this shape is
In the final rolling pass of the mill, the amount of web reduction was set to be larger than the amount of flange reduction, so that the extended flange portion spreads left and right at the exit of the rolling mill along the vertical roll. Furthermore, since the web is continuously strongly pressed, the web is restrained from extending in the longitudinal direction by the flange portion, and acts to restore its height and thickness.

As a result, the tip of the H-shaped cross section of the rolled material is
At the same time as the distribution of the inner width of the web spreading like a fan, the inner width of the web is slightly widened in the steady region. Therefore, if a rolling material with such a tip is rolled with a finish universal mill, the inner width of the web at the tip can be made larger than the horizontal roll width that is much larger than the inner width of the web in the steady region. Is. Then, the position where the horizontal roll spreads the inner surface of the flange is a position where the rolling material has been introduced to some extent, and the flange does not bite into the position corresponding to the web of the horizontal roll, and the tip of the rolling material to the horizontal roll. It becomes possible to bite.

In addition, when it is difficult to control the roll balance between the web and the flange during rolling in a coarse universal mill and it is difficult to control the tip crop shape because of the stability of the flange width in the longitudinal direction and the shape, a break occurs. If the web is thinned only at the tip of the rolling material in the rough rolling stage with a down mill and the edges are cut and aligned, the initial stage of the rough universal rolling (flange reduction )> (Web reduction ratio) occurs at the tip, so it is possible to adjust to a web negative shape. In the present invention, this phenomenon is also utilized as the second present invention. Hereinafter, the contents of the present invention will be captured and described in the embodiments of the drawings.

According to the present invention, the tongue cut at the tip is shown in FIG.
Cut so that the entire cross-section of the rolling material tip including the flange becomes the cut surface at position BB in (a), and the reduction ratio between the web and the flange in the coarse universal mill is flange> web. As a result, the cropped shape of the tip portion is a so-called web negative. At that time, as an application means for controlling the amount of the web negative, only the tip portion is thinly bite-back rolled by rolling in the breakdown mill 2 and after the tip thin web crop 9 as shown in FIG. It is more effective if the tongue is cut so that the entire cross section becomes a cut surface and the tip shape shown in FIG.

Further, in the present invention, in the final rolling pass in the rough universal mill, if the web reduction is increased within the range of the reduction balance that does not generate the web wave under the condition of the web reduction ratio> the flange reduction ratio, as shown in FIG. It is possible to obtain a cropped shape in which the tip end spreads in a fan shape as shown in FIG. With this shape, even if the roll width W ₂ of the finish universal mill 7 is wider than the roll width W ₁ of the rough universal mill 5, as shown in FIG. Does not bite into the web-corresponding parts of the horizontal rolls 7a and 7b, and moreover, even if there is a bend, the vertical rolls 7c and 7d come into early contact with each other, so that the so-called self-centering property is improved and the left and right flange tips m, m Even if the position of 'is deviated, it is possible to prevent the horizontal rolls 7a and 7b from being caught in the web-corresponding portions.

[0013]

EXAMPLE As a specific example, a slab of steel type SM490 was used, and the cross-sectional size was 650 × 200 × 9 × 12.
H-section steel (unit: mm) was manufactured. The numerical values of the size of the rolled material 8 in each rolling process are as follows. The web thickness tw ₀ before rolling in the coarse universal mill is 70.0 m.
m, the average flange thickness tf ₀ is 102.0 mm, the web thickness tw ₁ before the final rolling pass in the same rough universal mill is 9.3 mm, and the flange thickness tf ₁ is 12.8.
mm. Then, in the reciprocating rolling a plurality of times in the rough universal mill during this period, the relationship between the web reduction ratio and the flange reduction ratio is 86.7% <87.5%. On the other hand, in the final rolling pass in the rough universal mill, the web thickness tw ₁ = 9.1 mm and the flange thickness tf ₁ = 1.75.
mm, and the rolling reduction in this final pass is 2.15% for the web.
>> Flange 0.39%.

Further, the horizontal roll width W ₂ of the finishing universal mill is set to 630.4 mm, as opposed to 621.0 mm of the rough universal W ₁ , and the rough universal rolling is finished and the finished universal mill is fed to the finishing universal rolling mill. In the web width of the rolled material, X ₀ is about 621.7 at the position shown in FIG. 7.
mm, X ₁ was about 634.9Mm (Netsusun converted value).

As a result of carrying out the method for widening the inner width of the web according to the present invention under the above conditions, the width change angle θ of the flange tip becomes larger than the conventional angle shown in FIG.
As shown in (a), the flange tip has a horizontal roll 7a,
It was possible to operate smoothly by suppressing biting into 7b.

[0016]

As described above, according to the present invention,
After rough rolling with a breakdown mill, the tip of the rolled material was spread out in a fan shape by trimming the crop at the tip of the rolled material so that the entire cross section became the cut surface, and by appropriately adjusting the reduction of the flange and web in rough universal rolling. Because of the distribution of the inner width of the web, even a finishing universal rolling mill roll having a wider width than that of the rough universal rolling can be easily bited, and the rolling to increase the inner width of the web of the rolled material can be performed. Further, if the web thickness is made thin by carrying out bite-back only in the rough rolling, it is possible to control the so-called rolling material tip into a negative-shaped web even when rolling in a rough universal mill. Furthermore, according to the present invention, the rising angle of the flange width of the front end of the rolling material is increased, and the flange can be prevented from being wedged into the web-corresponding portion of the horizontal roll of the finishing universal rolling mill.

[Brief description of drawings]

FIG. 1 is an explanatory view of a crop shape after rough rolling in a breakdown mill according to the present invention, where (A) is a perspective view before cutting and (A) is a perspective view after cutting.

FIG. 2 is a diagram showing an example of a mill arrangement used for manufacturing an H-section steel.

FIG. 3 shows a cross section and a roll shape of a rolling material rolled by each rolling mill according to the conventional method.
After mill rolling, (a) shows the situation during rough universal mill rolling, (c) shows the situation at the final rolling pass in the rough universal mill, and (d) shows the situation at the finish universal mill.

FIG. 4 is an explanatory view of a crop shape after rough rolling in a breakdown mill, (A) is a perspective view, (A) is a perspective view.
Is a plan view.

5A and 5B are explanatory views of a situation in which a flange tip bites into a horizontal width variable roll by rolling in a finishing universal mill according to a conventional method, FIG. 5A is a plan view, and FIG. 5A is a side view.

6A and 6B are diagrams showing self-centering property in a finishing universal mill according to the application of the present invention, in which FIG. 6A is a plan view and FIG. 6A is a side view.

FIG. 7 is a web shape diagram of the tip end of a rolled material obtained in the final rolling stage in a coarse universal mill by applying the present invention.

[Explanation of symbols]

1 heating furnace 2 rough rolling mill 3 tongue cut saw 5 rough universal mill 6 edger mill 7 finishing universal mill 8 rolling material 9 crop tongue 2a, 2b horizontal roll for breakdown mill 5a, 5b for rough universal mill Horizontal rolls 5c, 5d Vertical rolls for coarse universal mills 6a, 6b Vertical rolls for edger mills 7a, 7b Variable horizontal width rolls for finishing universal mills 7c, 7d Vertical rolls for finishing universal mills θ Flange width Rise angle m Flange tip n Webtang tip tip tw Web thickness tf Flange thickness W ₁ , W ₂ Roll width X ₀ , X ₁ Web inner width

Claims (2)

[Claims] 1. An H-section steel in which a rolled material is sequentially rolled by a breakdown mill and a coarse universal mill, and then the horizontal roll width of the finishing universal mill is set to be wider than the horizontal roll width of the coarse universal mill. In the method of widening the inner width of the web, the leading end of the above-mentioned rolling material is cut and aligned so that the flange and the entire cross section of the web become the cut surface before rolling in the rough universal mill after rolling in the breakdown mill, and in the next step. The total rolling reduction of the rough universal mill before the final rolling pass is (flange rolling reduction)> (web rolling reduction), and the final rolling pass of the rough universal mill is (web rolling reduction)> (flange rolling reduction). Rate) is used for rolling, and a method for widening the inner width of the H-section steel web. 2. The method for widening the inner width of the H-section steel web according to claim 1, wherein the thickness of the web is made thinner at only the frontmost portion of the rolled material during rolling in the breakdown mill than at the rear portion thereof. .