JP2004114160A - Rolling method for shaped steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the rough rolling method for the shaped steel which can control an elongated bellows-like shape produced at the end portion of a rolled material in the last rolling stage following the rough rolling or in the intermediate rolling stage preceding the last rolling stage. <P>SOLUTION: In the rolling method which produces a shaped steel product by rolling a workpiece having rectangular section, the rough rolling process which can perform at least more than single pass level rolling and cross direction rolling is provided and, by estimating an ideal end shape in the rough rolling process from a difference in rolling reduction applied to each section of the rolled material in the shape rolling following the rough rolling process, the rough rolling is performed so that the workpiece may have such ideal end shape as is estimated. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for forming and rolling section steel.

FIG. 11 is an explanatory diagram of an example of the layout of the small-sized I-section steel rolling equipment.
Equipment used for rolling section steel is, from the upstream side, a heating furnace 1 for heating a material to be rolled such as bloom, a breakdown mill 3 for roughly rolling the material to be heated, and a hole shape for shaping an I-shaped steel. Double rolling mill 5 equipped with rolls, universal rolling mill group 7 comprising horizontal and vertical rolls and consisting of universal rolling mill and edger rolling mill, universal rolling mill 9 for finishing, tongue elongation and cut formed at the end Hot tong cut-and-sew 11.

An outline of the steps in the case of rolling an I-beam with the above equipment will be described.
As a material to be rolled, a bloom 13 as shown in FIG. 12 is heated in the heating furnace 1, and the heated bloom 13 is passed through upper and lower rolling rolls 17 and 18 having shaping holes 15 and 16 as shown in FIG. It is rolled and formed into a coarse shaped slab 19 (coarse angle) as shown in FIG.
Then, the subsequent double rolling mill 5 having the shaping die 21 as shown in FIG. 15, the universal rolling mill group 7 and the universal rolling mill 9 for finishing, the flange 25 and the web 27 as shown in FIG. Stretch-shaping and rolling until the product shape of the I-shaped steel 23 consisting of

Table 1 shows an example of the current rolling schedule for I-section steel in breakdown mill rolling.
The one shown in Table 1 is obtained by rolling a 200 mm × 100 mm (× 7 mm × 10 mm) I-beam from a bloom having a cross section of 250 mm × 310 mm.

ブ As shown in Table 1, the bloom 13 conveyed from the heating furnace 1 is first horizontally rolled by the molding die 15 (pass 1). Next, the bloom 13 is turned upright and edging-rolled in the opposite direction by the shaping die 16 (pass 2). Again, the bloom 13 is rolled to perform horizontal rolling (pass 3), and thereafter, similarly, horizontal rolling and edging rolling are alternately repeated, and a total of 5 passes are performed. That is, horizontal rolling is performed in odd passes, and edging rolling is performed in even passes.

At the time of rolling, at the front and rear ends of the material to be rolled, there occurs a phenomenon that the central portion in the width direction extends beyond both ends. Then, the ratio of the tongue elongation occurs on the front end side 1 and on the rear end side 3 in the rolling direction.
Therefore, focusing on the rear end side in the rolling direction where the tongue elongation is large, changes in the shape of the front and rear end portions of each pass are shown in FIG.
In FIG. 17, the state of the tongue elongation at the center in the width direction when viewed from a plane is indicated by "V" by taking a letter of the tongue, and the state of the tail fin shape of the fish at both ends extending beyond the center. Is displayed as "F" by taking one character of "Fish". In addition, the names of the front and rear ends of the bloom 13 are based on pass 1, the front end side of pass 1 is hereinafter referred to as the front end, and the rear end side of pass 1 is hereinafter referred to as the rear end.

In FIG. 17, H means horizontal rolling, and E means edging rolling. Furthermore, the arrows indicate the direction of rolling. Symbols such as E × 2 in the lowermost column indicate the number of times of rolling (E × 2 means edging rolling is twice). The same applies to FIGS. 1, 2, 5, 6, and 10 described later.

で は In pass 1, a tongue-extended shape is formed at the rear end (V). In pass 2, a tail fin shape is formed at the tip (F). In pass 3, the tongue extending shape at the rear end is further amplified (bebe). In pass 4, the shape of the tail fin at the tip is amplified (FF). In pass 5, the tongue shape at the rear end is further amplified (betty).

As a result, as shown in FIG. 18, the end portion of the crude steel slab 19 is shaped such that the rear end portion 29 has a tongue-extended shape and the front end portion 31 has a tail-fin shape.
When the rough slab 19 having such an end portion shape is stretched and shaped and rolled to the product shape by the subsequent double rolling mill 5, the universal rolling mill group 7, and the universal rolling mill 9 for finishing, FIG. Since the rolling reduction of the web portion is larger than that of the flange portion as shown in FIG. 20, large tongue elongation is formed at the rear end portion 29 of the material to be rolled as shown in FIG. Specific tongue elongation dimensions are L dimensions shown in FIG. 21, and the numerical values are as shown in Table 1.

ベ ロ Such a tongue-extended portion may cause vertical bending of the end of the material to be rolled, and may cause a reduction in rolling stability.

が Although the above description is for an I-section steel, the same applies to other sections. As another example, the case of unequal-sided unequal angle irons will be described. In the case of rolling unequal-sided unequal angle irons, the universal rolling mill group 7 and the finishing universal rolling mill 9 in FIG. Subsequent double rolling mills having a shaping die 33 as shown in FIG. 22 and finishing double rolling mills having a die shape closer to the product shape, thereby reducing the wall thickness as shown in FIG. Stretching and rolling are performed until the product shape of the unequal-sided angle steel 38 having the side 35 and the thin long side 37 is obtained.

In the rolling of the unequal-sided unequal thickness angle steel 38 as well, as in the case of the above-mentioned I-shaped steel, as shown in FIG.

In the case of unequal-sided unequal thickness angle steel, especially in the case of a large size (such as NAB500 × 150), at the stage of the breakdown mill 3, stretch forming rolling is performed so that the reduction ratio of the web portion is larger than the reduction ratio of the flange portion. Therefore, at the time of finishing the breakdown mill, the tongue elongation as shown in FIG. 24 is generated particularly at the rear end.
When this tongue stretched portion is rolled by a subsequent double rolling mill, it induces vertical bending and bending at the end of the material to be rolled, giving out a lap-like flaw on the surface and causing a surface defect of the product. Will be invited. For this reason, after the breakdown mill rolling, it is necessary to cut and remove the tongue-extended portion with a tongue cut saw, which requires extra man-hours and causes waste of material.

As described above, in rolling in a conventional breakdown mill, horizontal rolling and edging rolling were sequentially repeated without paying particular attention to the end shape of the material to be rolled. There is a problem that a tongue-extended shape is formed at the end of the steel sheet, and this is further amplified in the subsequent rolling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and is intended to reduce the shape of a profiled steel capable of suppressing the tongue elongation shape generated at the end of the material to be rolled in the final rolling stage following the rough rolling or in the intermediate rolling stage before the rough rolling. The aim is to obtain a rolling method.

The rolling method according to the present invention is a rolling method for rolling and manufacturing a shaped steel product from a rectangular cross-section material, comprising a rough rolling step capable of at least one pass of horizontal rolling and width rolling, and forming and rolling following the rough rolling step Predicting a suitable end shape in the rough rolling step from a difference in reduction rate applied to each part of the material to be rolled in the above, and performing the rough rolling so as to have the predicted preferable end shape. Things.

(4) In the rough rolling step, at least one step in which the end of the material to be rolled on the rear end side in the horizontal rolling is also on the rear end side in the width direction rolling is characterized in that it is characterized by having at least one step.

Further, when there is a difference in the number of passes in each direction of horizontal rolling, the end of the material to be rolled on the rear end side in the rolling direction with a large number of passes of horizontal rolling is rolled as the rear end side in the width direction rolling. And a reduction amount in the step is set to be larger than a reduction amount in another width direction rolling.

{Circle around (1)} The characteristic is that the ratio w / t of the width: w and the thickness: t of the rectangular section material is set in the range of 1.3 to 2.1.

Furthermore, the angle of engagement with the rectangular section material is adjusted.

Furthermore, the pair of roll hole shapes used for the width direction rolling are asymmetric.

As described above, in the present invention, a rolling method for rolling and manufacturing a shaped steel product from a material having a rectangular cross section includes a rough rolling step capable of performing horizontal rolling and width direction rolling of at least one pass or more, and shaping rolling subsequent to the rough rolling step. Predicting a suitable end shape in the rough rolling step from a difference in reduction rate applied to each part of the material to be rolled in the above, and performing the rough rolling so as to have the predicted preferable end shape. As a result, it is possible to reduce the tongue elongation in the subsequent shaping and rolling.
Thereby, troubles in the rolling process such as poor rolling bite in the subsequent forming rolling can be reduced, and the rolling stability can be improved.

Embodiment 1 FIG.
The present embodiment relates to rolling of an I-section steel.
In the rolling of an I-section steel, since the rolling amount of the web is larger than that of the flange portion in a double rolling mill or the like subsequent to the breakdown mill, the central portion of the material to be rolled is extended to have a tongue-stretched shape. Therefore, in the finished state of the breakdown mill, by forming both ends flat, preferably in the shape of a tail fin, it is possible to suppress the occurrence of tongue elongation.
Therefore, in the present embodiment, the occurrence of tongue elongation at the end of the material to be rolled is suppressed by adjusting the rolling schedule in the breakdown mill.

Specifically, in the conventional example, horizontal rolling and edging rolling were performed alternately, but this schedule was changed so that the tongue elongation formed by horizontal rolling was corrected to flat or tail fin shape by edging rolling. It is.
Table 2 shows the path schedule according to the present embodiment.

Table 2 shows the cross-sectional dimensions, rolling reduction, and tongue elongation dimensions for each pass. As shown in Table 2, in the present embodiment, horizontal rolling is performed in pass 1, edging rolling in pass 2, edging rolling in pass 3, edging rolling in pass 4, and horizontal rolling in pass 5. In addition, the tongue elongation dimension shows the range by measuring the tongue elongation as a result of several rolling experiments.

FIG. 1 is a diagram showing a change in the shape of the front and rear ends of each path according to the path schedule of the present embodiment shown in Table 2.
The shape of the end of the material to be rolled in each pass will be described with reference to FIG. First, in pass 1, tongue elongation is formed on the rear end side of the material to be rolled. The names of the front and rear ends of the material to be rolled are referred to as the rear end of the material to be rolled in the pass 1 and the front end of the material to be rolled in the pass 1 in the same manner as described in the conventional example.
In pass 2, a tail-fin shape is formed on the tip side (F). In pass 3, a tail fin shape is added to the tongue elongation on the rear end side of the material to be rolled formed in pass 1, and the material is corrected in a flat direction (be F). Since the amount of reduction of the pass 3 is increased, the shape of the tail fin is slightly overcome by overcoming the tongue-extended shape.
In pass 4, the tail fin shape of the tip formed in pass 2 is returned to a substantially flat state (F). In pass 5, the tail fin shape of the rear end formed in pass 3 is returned to a substantially flat state (be-F-be).

As described above, according to the pass schedule of the present embodiment, the shape of both ends becomes substantially flat. As shown in Table 2, the front and rear end portions of the end product at the final product finishing stage in which this was rolled by a subsequent double rolling mill or the like have a Velo elongation of 200 mm to 250 mm at the front end and 220 mm to 270 mm at the rear end. , And the total is 420 mm to 520 mm.

When this result is compared with the conventional example, the tongue elongation is 50 mm larger than that of the conventional example at the front end portion, but the tongue elongation is 130 mm smaller at the rear end portion, and the tongue elongation dimension is reduced by 80 mm in total. .

As can be seen from the results, in the present embodiment, by adjusting the rolling schedule, the shape of both ends of the material to be rolled can be flattened, and when rolling is performed by a subsequent double rolling mill or the like. Velo growth at the front and rear ends can be suppressed.
By reducing the tongue elongation, it is possible to prevent vertical bending and bending of the material to be rolled in a subsequent double rolling or universal mill comprising an edger and a group of universal rolling mills, and it is equipped before and after the rolling mill. There is also an expected effect of reducing the lap flaws and scratches of the material to be rolled caused by contact with the guiding guide and the table, thereby contributing to the improvement of the product yield.

Embodiment 2 FIG.
In the second embodiment, the pass schedule as in the first embodiment is adopted, and the width of the bloom is increased to increase the width-to-thickness ratio (w / t). Specifically, the width of the bloom W is 310 mm in the conventional and the first embodiment, but is changed to 330 mm in the second embodiment. While the width / thickness ratio of the conventional and the first embodiment is w / t = 310/250 = 1.24, in the present embodiment, w / t = 330/250 = 1.32. 6% larger.

The specific path schedule of the present embodiment is as shown in Table 2 above. As shown in Table 2, the tongue elongation is 150 mm to 200 mm at the front end and 170 mm to 220 mm at the rear end, for a total of 320 mm to 420 mm.
Comparing this with the conventional example, the front end side is the same as the conventional example, and the rear end side is greatly improved to 180 mm, and the total is greatly improved to 180 mm. Also, compared to the first embodiment, there is an improvement in all of the front end side, the rear end side, and the total.

From this result, by increasing the width-to-thickness ratio (w / t) of the bloom, the amount of reduction by edging rolling is increased, and a tail fin is easily formed. As a result, a shape suitable for manufacturing an I-shaped steel is obtained. Things.
In the above example, it was proved that the effect was obtained when the width-to-thickness ratio (w / t) was set to 1.32, but in short, the width-to-thickness ratio (w / t) was made larger than that of the conventional one. This has a certain effect. However, a practical range of the width-thickness ratio (w / t) is 1.3 to 2.1.

Embodiment 3 FIG.
This embodiment relates to the rolling of unequal-sided unequal thickness angle steel.
In the rolling of unequal-sided unequal thickness angle steel, the amount of reduction on the thin long side is larger than that on the short side in the double rolling mill following the breakdown mill. It is greatly stretched and becomes a tongue stretched shape.
In order to prevent this, in the finished state of the breakdown mill (in the case of a large product, before stretching and rolling), the both ends are flat, and preferably, the thickness is set to the side that is the thinner side in the product state. By securing the amount, it is possible to suppress the occurrence of the velo growth.
Therefore, in the present embodiment, by adjusting the rolling schedule in the breakdown mill, the end of the material to be rolled is made almost flat, thereby suppressing the occurrence of the tongue elongation.

　表３に示した例は、２５０ｍｍ×３１０ｍｍの断面を有する素材ブルームから２５０ｍｍ×９０ｍｍ（×１０ｍｍ×１５ｍｍ）の不等辺不等厚山形鋼を圧延する場合である。
　図２は表３に示した本実施の形態のパススケジュールによる各パスの先後端部の形状の変遷を、従来例と対比して示した図である。
　図２に基づいて、各パスにおける被圧延材の端部形状を、本実施の形態を中心に従来法と比較しつつ説明する。 Table 3 shows a comparison between the conventional method and the present embodiment.

The example shown in Table 3 is a case where a 250 mm × 90 mm (× 10 mm × 15 mm) unequal unequal thickness angle steel is rolled from a material bloom having a cross section of 250 mm × 310 mm.
FIG. 2 is a diagram showing a change in the shape of the front and rear end portions of each path according to the path schedule of the present embodiment shown in Table 3 in comparison with a conventional example.
Based on FIG. 2, the shape of the end portion of the material to be rolled in each pass will be described focusing on the present embodiment while comparing with the conventional method.

{Circle over (1)} In pass 1, a tongue elongation is formed on the rear end side of the material to be rolled (V). In pass 2, a tail-fin shape is formed on the tip side (F). Up to this point, the conventional method and the present embodiment are the same.

In pass 3, a tail fin shape is added to the rear end shape (be) of the material to be rolled formed in pass 1 (be F). In particular, since the amount of reduction of the pass 3 is increased, the shape of the tail fin is weakened by overcoming the tongue-extended shape.
On the other hand, in the conventional method, the tongue elongation is added to the tongue elongation formed in pass 1 (bebe).
In pass 4, the tip shape (F) formed in pass 2 is added to the tongue extension to return to a substantially flat state (F).
On the other hand, in the conventional method, the tail fin shape is further added to the tail fin shape (F) formed at pass 2 (FF).

In pass 5, the back end shape (bevel F) formed in pass 3 is added with tongue extension to return to a substantially flat state (between f).
On the other hand, in the conventional method, the back end (bebe) formed in pass 3 is further increased in belo (bebebe).
In pass 6, the tip (F) tail fin shape formed in pass 4 is added, resulting in a weak tail fin shape (F). The tip is the final shape in the breakdown mill.
On the other hand, in the conventional method, a tail fin shape is further added to the tip portion shape (FF) formed in pass 4 (FFF).

In pass 7, the rear end shape (bevel F) formed in pass 5 is further increased in tongue (bevel F).
On the other hand, in the conventional method, the rear end portion (bebebe) formed by the pass 5 is further added with a tongue-extended shape (bebebebe).

From the above, the final shape of the breakdown mill of the present embodiment has a rear end portion of (bevel F-bebe), a weak velvet extension shape, and a front end portion of (F-bevel) with a weak tail fin shape.
On the other hand, in the conventional method, the rear end portion is (bebebebe), and the front end portion is (FFF) and has a strong tail fin shape.

Table 3 (column of Embodiment 3) shows the tongue elongation of the end when the material to be rolled having the above-described end shape is rolled by the subsequent double rolling mill.
As can be seen from Table 4, an improvement of 100 mm was observed at both the front and rear ends, and a total improvement of 200 mm was observed.

As described above, in the present embodiment, the rolling schedule in the breakdown mill was adjusted to bring the end of the material to be rolled closer to flat, thereby suppressing the occurrence of tongue elongation.

Embodiment 4 FIG.
This embodiment relates to the rolling of unequal-sided unequal thickness angle steel.
In the present embodiment, it is intended to suppress the tongue elongation by securing in advance the thickness of the flange on the flange side where the elongation is small at the time of finishing the breakdown mill.

Specifically, the thickness short side of the unequal-sided unequal thickness angle steel has a small elongation in the subsequent rolling, so that the thickness of this portion is secured in advance at the time of finishing the breakdown mill.
That is, as shown in FIG. 3, by raising the height of the rolled material 13 with respect to the rolls 17 and 18, the bite angle between the rolls 17 and 18 forming a pair, that is, the bite of the rolled material 13 is increased. A difference is made in the metal flow at the end, a difference in elongation is generated in the width of the biting end, and a protrusion 43 (deco 43) as shown in FIG.

FIG. 5 is a diagram showing the transition of the shape of the front and rear ends of each path according to the path schedule of the present embodiment.
Hereinafter, the end shape of the material to be rolled in each pass will be described with reference to FIG. The pass schedule itself (the order of horizontal rolling and edging rolling) is the same as in the conventional example.
N in the lowermost column of FIG. 5 means rolling that causes a difference in elongation in the width of the biting end described above.

{Circle over (1)} In pass 1, a tongue elongation is formed on the rear end side of the material to be rolled (V). In pass 2, a tail-fin shape is formed on the tip side (F). Further, in pass 2, the roll height is adjusted, and the rear end side is the front side in the traveling direction, so that the deco shown in FIG. 4 is formed on the upper side of the rear end side. Therefore, on the rear end side, a deco is formed in addition to the tongue elongation of the pass 1 (bed).

In pass 3, tongue elongation is added to the shape (bed) of the rear end of the material to be rolled formed in pass 2 (bed).
In the pass 4, a tail fin shape is further added to the tip shape (F) formed in the pass 2 (FF). Also, the deco is formed at the rear end portion, and the deco is formed at the rear end side in addition to (Bedbede) of the path 3 (Bedebede).

In pass 5, the trailing edge (bed-bede) formed in pass 4 is further increased in tongue (bed-be-deve).
In pass 6, the tail fin shape is further added to the tip shape (FF) formed in pass 4 (FFF). Further, the deco is further formed at the rear end portion, and the deco is formed at the rear end side in addition to the (development) of the path 5 (development).
In pass 7, the rear end shape (bed-be-be-be-de) formed in pass 6 is further increased in tongue (bed-be-be-be-be).

か ら From the above, the final shape of the breakdown mill of the present embodiment is (flat) at the rear end, almost flat, and the front end is the same as the conventional method (FFF) and has a strong tail fin shape.

　表４からわかるように、先端側は従来法と同じであるが、後端側で２００ｍｍの改善がみられ、合計では２００ｍｍの改善がみられる。 Table 4 (Embodiment 4 column) shows the tongue elongation dimension of the end when the material to be rolled having the above-mentioned end shape is rolled by the subsequent double rolling mill.

As can be seen from Table 4, the front end side is the same as the conventional method, but the rear end side has an improvement of 200 mm and a total improvement of 200 mm.

As described above, in the present embodiment, it is possible to suppress the tongue elongation by previously securing the thickness of the flange side with a small elongation at the time of finishing the breakdown mill.

Embodiment 5 FIG.
This embodiment relates to the rolling of unequal-sided unequal thickness angle steel.
In the present embodiment, the pass schedule shown in the third embodiment is implemented, and the bite angle shown in the fourth embodiment is adjusted.

FIG. 6 is a diagram showing a change in the shape of the front and rear end portions of each path according to the path schedule of the present embodiment. In FIG. 6, the symbols attached to the shapes of the front and rear ends are the same as those shown in the first to fourth embodiments.
The description of the end shape in each pass is omitted, but in the final stage, the front end side is (F-development F), and the upper end side is slightly protruding. Further, the rear end side is (bed F bed) and has a substantially flat shape.

Looking at the tongue elongation dimension of this embodiment, it can be seen that, compared to the conventional example, the tongue elongation is reduced by about 150 mm to 200 mm on the front end side and 200 mm to 250 mm on the rear end side, for a total of about 350 mm to 450 mm. .

In Embodiments 4 and 5 described above, an example in which the height of the material to be rolled is adjusted in all edging rolling has been described, but the present invention is not limited to this, and any one of edging rolling is applicable. Even if the height is adjusted in the pass, a certain effect can be obtained.

Embodiment 6 FIG.
This embodiment also relates to rolling of unequal-sided unequal thickness angle steel.
In the present embodiment, as in the fourth embodiment, the thickness of the flange on the side of the flange having a small expansion is secured in advance at the time of finishing the breakdown mill, thereby suppressing the tongue expansion.
Specifically, by using a vertically asymmetric roll in the edging rolling, a difference is caused in the thickness of the material to be rolled, and in the subsequent horizontal rolling, a difference in elongation is generated in the width direction of the front and rear ends of the material to be rolled, and in the final product, The thickness of the flange on the side of the flange with a small extension is secured in advance at the time of finishing the breakdown mill.

FIG. 7 shows a vertically asymmetric roll in a breakdown mill. By rolling with the asymmetric rolls 45 and 47 shown in FIG. 7, the lower side can be formed into a thick trapezoidal cross section as shown in FIG. By horizontally rolling this, as shown in FIG. 9, a projection 49 can be formed in the axial direction at the end on the thick side.
As a result, the thickness of the unequal-sided unequal thickness angle steel on the flange side where the elongation is small can be secured in advance at the time of finishing the breakdown mill.

FIG. 10 is a diagram showing the transition of the shape of the front and rear ends of each path according to the path schedule of the present embodiment.
The shape of the end of the material to be rolled in each pass will be described with reference to FIG.
In addition, the symbol of non-E in the lowermost column of FIG. 10 means edging rolling with a vertically asymmetric roll.

First, in horizontal rolling in pass 1, a tongue elongation is formed on the rear end side of the material to be rolled (V).
In the edging rolling of pass 2, a vertically asymmetric roll is used, and a difference in thickness (denoted as “thickness difference” in the drawing) occurs vertically. In this case, the leading end portion on the rolling bite-releasing side has a tail fin shape smaller than that of normal edging rolling—strictly, a shape in which the upper end portion of the narrow upper and lower asymmetrical rolls slightly extends—is formed ( f).

In pass 3 edging rolling, a further thickness difference occurs. Further, the trailing end portion on the rolling bite release side has a tail fin shape smaller than that of ordinary edging rolling in the trailing end shape (V) of the material to be rolled formed in pass 1-strictly speaking, a vertically asymmetric roll. The shape in which the upper end having a small width is slightly extended is added (bef).
In the horizontal rolling of pass 4, the tip side is the side where the tongue elongation occurs, but the thickness difference formed in passes 2 and 3 is crushed, and a convex portion is formed at the tip end on the thicker side. (F convex).

In the horizontal rolling of pass 5, since the rear end side is the side where the tongue elongation occurs, the tongue elongation formed by pass 3 plus a small tail fin shape is further amplified to the tongue elongation (bef B).
In the edging rolling of the pass 6, a thickness difference occurs, and a small tail fin shape is added to the tip side (f convex f).
In the horizontal rolling of the pass 7, the rear end side is the side where the tongue elongation occurs, but the thickness difference formed in the pass 6 is crushed, and a convex portion is formed at the rear end portion of the thicker side. (Bef convex).

From the above, the final shape in the breakdown mill of the present embodiment is (f convex f 2) on the front end side, is a suitable shape convex on the upper end, and is (convex convex) on the rear end side, Although the degree of protrusion is smaller than the tip side, it is still a suitable shape.

Table 4 (column of the sixth embodiment) shows the tongue elongation of the end when the material to be rolled having the above-mentioned end shape is rolled by the subsequent double rolling mill.
As can be seen from Table 4, an improvement of 200 mm to 250 mm on the front end side and 200 mm on the rear end side, that is, an improvement of 400 mm to 450 mm in total is observed as compared with the conventional example.

As described above, in the present embodiment, while adjusting the rolling schedule in the breakdown mill, and using a vertically asymmetric roll in the edging rolling, the thickness of the flange side with a small end elongation in the final product is reduced. At the time of finishing the breakdown mill, it could be secured in advance, and as a result, the occurrence of toroidal elongation could be suppressed.

In the above description, the I-section steel and the unequal-sided unequal thickness angle steel have been described as examples. However, the present invention is not limited to these, and it can be similarly applied to other shapes of section steel. Needless to say.

FIG. 7 is a diagram illustrating a change in the shape of the front and rear ends of each path according to the path schedule according to the embodiment of the present invention. It is a figure showing transition of the shape of the front-and-rear end part of each pass by the pass schedule of other embodiments of the present invention. It is an explanatory view of an apparatus of another embodiment of the present invention. It is explanatory drawing of the shape of the edge part of the to-be-rolled material of the rolling result by other embodiment of this invention. It is a figure showing transition of the shape of the front-and-rear end part of each pass by the pass schedule of other embodiments of the present invention. It is a figure showing transition of the shape of the front-and-rear end part of each pass by the pass schedule of other embodiments of the present invention. It is an explanatory view of an asymmetric roll of another embodiment of the present invention. It is explanatory drawing of the shape in the middle of rolling of the to-be-rolled material of other embodiment of this invention. It is explanatory drawing of the shape in the middle of rolling of the to-be-rolled material of other embodiment of this invention. It is a figure showing transition of the shape of the front-and-rear end part of each pass by the pass schedule of other embodiments of the present invention. It is explanatory drawing which shows an example of the layout of the I-shaped steel rolling equipment of small size. It is explanatory drawing of the external shape of a bloom. It is explanatory drawing of the up-down rolling roll of a breakdown mill. It is explanatory drawing of the external shape of a crude steel slab. It is explanatory drawing of the upper and lower roll of a double type rolling mill. It is explanatory drawing of the product shape of an I-beam. It is a figure showing transition of the shape of the front-and-rear end part of each pass by the pass schedule of the conventional method. It is explanatory drawing of the edge part shape of the rough shaped steel slab after rolling by the conventional method. It is explanatory drawing of the subject of this invention. It is explanatory drawing of the subject of this invention. It is explanatory drawing of the subject of this invention. It is explanatory drawing of the subject of this invention (explanatory drawing of the roll hole type of unequal-sided unequal thickness angle steel). BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the subject of this invention (explanation drawing of the product shape of unequal-sided unequal thickness angle steel). It is explanatory drawing of the subject of this invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Heating furnace 3 Breakdown mill 5 Double rolling mill 7 Universal rolling mill group 9 Universal rolling mill for finishing 11 Hot tong cut-sew 13 Bloom 15, 16 Modeling die 17, 18 Vertical rolling roll 19 Coarse steel slab 21 Modeling hole Mold 23 I-shaped steel 25 Flange 27 Web 29, 39 Rear end 31, 41 Tip 33 Molding hole 35 Thick short side 37 Thin long side 38 Irregular unequal thickness angle steel 43 Deco 49 Convex part

Claims (6)

In a rolling method of rolling and manufacturing a shaped steel product from a rectangular cross-section material, a rough rolling step capable of at least one pass of horizontal rolling and width rolling is provided, and each part of a material to be rolled in shaping rolling subsequent to the rough rolling step Rolling method, wherein a suitable end shape in the rough rolling step is predicted from a difference in reduction ratio applied to the rough rolling, and the rough rolling is performed so as to have the predicted preferable end shape. 2. The rolling method according to claim 1, wherein the rough rolling step includes at least one step in which the end of the material to be rolled on the rear end side in horizontal rolling is also on the rear end side in width direction rolling. In the case where there is a difference in the number of passes in each direction of the horizontal rolling, the step of rolling the end of the material to be rolled on the rear end side in the rolling direction with a large number of passes of the horizontal rolling as the rear end side in the width direction rolling. 3. The rolling method according to claim 2, wherein the reduction amount in the step is set to be larger than the reduction amount in another width direction rolling. The ratio w / t of the width: w and the thickness: t of the rectangular cross-section material is set so as to be in a range of 1.3 to 2.1. Rolling method. 5. The rolling method according to any one of claims 1 to 4, wherein a biting angle with respect to the rectangular section material is adjusted. The rolling method according to any one of claims 1 to 4, wherein the pair of roll hole shapes used in the width direction rolling are asymmetric.

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