WO2017014047A1

WO2017014047A1 - Method for manufacturing shaped steel

Info

Publication number: WO2017014047A1
Application number: PCT/JP2016/069937
Authority: WO
Inventors: 高嶋　由紀雄; 寛人後藤
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2015-07-23
Filing date: 2016-07-05
Publication date: 2017-01-26

Abstract

When manufacturing shaped steel in which the configuration of a cross-section perpendicular to the long direction has: a web extending in one direction; a first flange formed on one end of the web; and a second flange formed on the other end of the web, the second flange being wider that the first flange, universal rolling is performed such that the reduction of the first flange is made larger than the reduction of the second flange, and the reduction of the first flange is no less than the reduction of the web.

Description

Manufacturing method of shape steel

The present invention relates to a method for producing a shape steel using universal rolling.

Usually, the cross-sectional shape perpendicular to the longitudinal direction of the rail is a shape having an abdomen extending in one direction, a head and a foot formed at both ends of the abdomen, and a cross-sectional shape of the head and the foot. Is different. For this reason, the rail has an asymmetric cross-sectional shape on the right side and the left side in the horizontal direction with the abdomen as a boundary in a sideways state where the abdomen is horizontal. In the following, a shape steel having an asymmetric cross-sectional shape in the horizontal direction with the web being horizontal is referred to as a left-right asymmetric shape steel.

In recent years, a hot rolling method using a universal rolling mill has become widespread as a method for producing a shape steel having a left-right asymmetric cross-sectional shape such as a rail. In general, a universal rolling mill has four rolls, an upper and lower horizontal roll to be driven and left and right vertical rolls that are not driven, and these roll axes are arranged on the same plane perpendicular to the rolling direction. . In the shape steel rolled using such a universal rolling mill (also called “universal rolling”), the horizontal portion rolled between the upper and lower horizontal rolls is called a web, and the side of the horizontal roll and the side roll The vertical part rolled in between is called the flange. That is, when rolling the rail with a universal rolling mill, the abdomen corresponds to the web, the head corresponds to the flange on one end, and the foot corresponds to the flange on the other end. For example, Patent Document 1 discloses a method of performing universal rolling in a left-right asymmetric posture in which a rail web is horizontal as a technique for manufacturing a rail.

Japanese Patent Publication No.46-17575

However, when rolling an asymmetrical shape steel, the left and right flanges have different shapes, and thus bending may occur in the left-right direction. If this bending is large, the rolled material may jump out of the transport line, or the rolled material may not be properly guided between the rolls of the next rolling mill and may collide with surrounding equipment. There is. In the method described in Patent Document 1, the rolling condition for reducing the horizontal bending is not clarified, and thus the horizontal bending may occur.
Then, this invention is made | formed paying attention to said subject, and provides the manufacturing method of the shape steel which can suppress the bending in the left-right direction when manufacturing an asymmetrical shape steel by universal rolling. The purpose is that.

According to one aspect of the present invention, a cross-sectional shape perpendicular to the longitudinal direction is formed in a web extending in one direction, a first flange formed at one end of the web, and at the other end of the web, When manufacturing a shape steel having a shape having a second flange wider than the first flange, the reduction rate of the first flange is made larger than the reduction rate of the second flange, and the first There is provided a method for producing a shape steel, characterized in that universal rolling is performed under a condition in which a reduction rate of the flange is equal to or higher than the reduction rate of the web.

According to one aspect of the present invention, when a left-right asymmetric shape steel is produced by universal rolling, bending in the left-right direction can be suppressed.

It is a front view which shows the universal rolling mill which concerns on one Embodiment of this invention. It is sectional drawing which shows the rolling material before universal rolling. It is sectional drawing which shows the cross-sectional shape of a rail.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
<Configuration of rolling equipment>
With reference to FIG.1 and FIG.3, the rolling equipment which concerns on one Embodiment of this invention is demonstrated. In the present embodiment, the rail S is manufactured as a left-right asymmetric shape steel by a rolling facility including the universal rolling mill 1.

As shown in FIG. 3, the rail S has a shape in which a cross-sectional shape perpendicular to the longitudinal direction is composed of a head S1, an abdominal part S2, and a foot part S3. The abdomen S2 is a part extending in the left-right direction with respect to the paper surface of FIG. The head S1 is formed at one end of the abdomen S2 (right end with respect to the paper surface of FIG. 3), and extends in a direction perpendicular to the direction in which the abdomen S2 extends (up and down direction with respect to the paper surface of FIG. 3). The foot S3 is formed at the other end of the abdomen S2 (the left end with respect to the paper surface of FIG. 3) and extends in a direction perpendicular to the direction in which the abdomen S2 extends. Further, the foot part S3 is formed so as to have a width (length in the vertical direction with respect to the paper surface of FIG. 3) longer than the head part S1.

In addition to the universal rolling mill 1, the rolling equipment of this embodiment includes a heating furnace (not shown), a rough rolling mill, and a forming rolling mill. The heating furnace is a device for heating a steel piece such as a rectangular cross section that is a material of the rail S, and is disposed on the most upstream side of the production line. The rough rolling mill is a rolling mill that rolls the steel slab heated in the heating furnace into a cross-sectional shape suitable for universal rolling in the universal rolling mill 1, and is downstream of the heating furnace and upstream of the universal rolling mill 1. Arranged. The forming rolling mill is a rolling mill in which upper and lower perforated rolls are incorporated, and is arranged in the vicinity of the universal rolling mill 1 as in Patent Document 1. The rough rolling mill, the forming rolling mill, and the universal rolling mill 1 may be repetitively arranged on the production line according to rolling conditions.

The universal rolling mill 1 has a pair of

horizontal rolls

2a, 2b, a first roll 3 and a second roll 4 as shown in FIG. FIG. 1 shows a state of universal rolling according to the present embodiment, and shows a front view of the universal rolling mill 1 at the center of the roll axis as viewed from the rolling direction. In this embodiment, the rail S is rolled in a state in which the cross-sectional shape is asymmetric in the horizontal direction (left-right direction with respect to the paper surface in FIG. 1) and symmetrical in the vertical direction (up-down direction with respect to the paper surface in FIG. 1). For this reason, a pair of

horizontal rolls

2a and 2b have the same roll shape according to the shape of the desired rail S. On the other hand, the first reed roll 3 and the second reed roll 4 have different roll shapes according to the desired shape of the rail S. Further, the pair of

horizontal rolls

2a and 2b has an opening degree corresponding to the position of the

horizontal rolls

2a and 2b in the vertical direction, and the first roll 3 and the second roll 4 have positions of the

rolls

3 and 4 in the horizontal direction. The opening degree is configured to be set independently. Thereby, since the universal rolling mill 1 is comprised so that adjustment of the rolling reduction of the head S1, the abdominal part S2, and the foot | leg part S3 of the rail S is possible independently, it can implement universal rolling of the conditions mentioned later easily. it can.

<Method for producing shape steel>
In the universal rolling, there is a problem that when a shape steel that is asymmetrical like the rail S is rolled, bending is likely to occur in the left-right direction. Bending in the left-right direction causes a major trouble as described above. In addition, when the bending in the left-right direction occurs, the rolling material is rolled in the left-right direction from the roll in further downstream rolling, so that a desired cross-sectional shape cannot be obtained and a dimensional defect may occur.

Therefore, as a result of earnestly researching the relationship between the rolling conditions of the universal rolling mill 1 and the bending in the left-right direction, the present inventors set the relationship between the rolling reduction ratios in the left-right direction, thereby making the bending in the left-right direction. We found that it is possible to reduce. Furthermore, in order to implement smooth rolling, the inventors have obtained the knowledge that the relationship between the rolling ratio between the abdominal part S2 and the head part S1 rolled by the upper and lower horizontal rolls is important, and these The appropriate relationship of the rolling reduction was derived.

A method for manufacturing a shape steel according to this embodiment based on the above knowledge will be described. In this embodiment, first, the steel material is heated in a heating furnace until it reaches a predetermined temperature. Next, the heated steel material is roughly rolled by a roughing mill, so that the cross-sectional shape of the steel material is suitable for universal rolling. Furthermore, the rail S of desired cross-sectional shape is manufactured by carrying out the intermediate rolling and the finish rolling of the rough-rolled steel raw material in the universal rolling mill 1 and the forming rolling mill. Detailed conditions of universal rolling will be described later. These hot rolling by the rough rolling mill, the universal rolling mill 1 and the forming rolling mill are performed in the order of a predetermined hole shape in accordance with a desired cross-sectional shape and reduction ratio, and multiple times by the same rolling mill ( Multiple passes) may be performed.

In the universal rolling, rolling is performed under the condition that the rolling reduction of the head S1 of the rail S is larger than the rolling reduction of the foot S3 and equal to or more than the rolling reduction of the abdominal part S2. In addition to this rolling reduction condition, it is preferable that the rolling reduction difference obtained by subtracting the rolling reduction of the foot S3 from the rolling reduction of the head S1 is 8% or less. The reduction ratios of the head S1, the foot S3, and the abdomen S2 are independently adjusted by adjusting the opening degree of the first heel roll 3, the second heel roll 4, and the pair of

horizontal rolls

2a and 2b. Is done.

The rolling reduction is preferably calculated from the average plate thickness at the head S1 and the foot S3. However, in the case of a shape steel configured with a curve like the rail S, representative of each part shown in FIG. It may be calculated using the thickness. FIG. 2 is a diagram illustrating a cross-sectional shape of the rail S that is a rolled material before universal rolling. As shown in FIG. 2, even before universal rolling, the rail S is formed at the abdomen S2 extending in the horizontal direction and at one end of the abdomen S2, as in FIG. It is roughly divided into three parts: S1 and a foot part S3 which is formed at the other end of the abdominal part S2 and has a thinner plate thickness than the head part S1. The abdomen S2 is rolled with a pair of

horizontal rolls

2a and 2b, the head S1 is rolled with a first heel roll 3, and the foot S3 is rolled with a second heel roll 4. Here, when the width (height in the vertical direction) of the head S1 is A [mm], the representative thickness d ₁ [mm] of the head S1 is A in the width direction from the center in the width direction of the head S1. The thickness at the position of / 4 [mm] (the length in the horizontal direction). Further, when the width (height in the vertical direction) of the foot part S3 is B [mm], the representative thickness d ₂ [mm] of the foot part S3 is B / B in the width direction from the center in the width direction of the foot part S3. It is the thickness (the length in the horizontal direction) at a position of 4 [mm]. Furthermore, the representative thickness w [mm] of the abdominal part S2 is the thickness at the position where the thickness (the length in the vertical direction) of the abdominal part S2 is the thinnest. In this embodiment, the rolling reduction is calculated from these representative thicknesses before and after universal rolling.

The reason why the bending in the left-right direction can be suppressed by the relationship of the rolling reduction between the head S1 and the foot S3 will be described below. As shown in FIG. 2, the cross-sectional shape of the rail S is such that the width A of the head S1 is narrower than the width B of the foot S3. In this case, since the head S1 has a smaller contact width with the roll than the foot S3, friction in the width direction is smaller in the head S1. For this reason, in the universal rolling, the head S1 is more easily deformed in the width direction, so that the widening deformation in the head S1 is increased. That is, even if rolling is performed at the same sheet thickness reduction rate, the larger the width spread, the smaller the stretching in the rolling direction. For this reason, the stretch amount on the head S1 side becomes smaller than the stretch amount on the foot S3 side, and as a result, a lateral bending toward the head S1 side occurs.

However, as described above, by making the rolling reduction rate of the head S1 larger than the rolling reduction rate of the foot S3, unevenness in the stretching amount of the head S1 and the foot S3 is corrected, so that the bending in the left-right direction is performed. Can be reduced. However, if the rolling reduction rate of the head S1 is excessively increased with respect to the foot S3, it may be difficult to bite into the roll on the head S1 side, and universal rolling is unstable. Therefore, smooth operation may be hindered. For this reason, it is preferable that the rolling reduction difference between the head S1 and the foot S3 is 8% or less.

Next, the reason why the bending in the left-right direction can be suppressed by the relationship between the reduction ratios of the head S1 and the abdomen S2 will be described below. The abdominal part S2 is characterized in that it is difficult to cause widening due to universal rolling because both ends in the horizontal direction are surrounded by the head part S1 and the foot part S3. However, during universal rolling, metal flow from the abdominal part S2 to the head part S1 or the foot part S3 may occur, and the present inventors investigated in detail the relationship between these rolling reductions.

As a result of the investigation, the present inventors performed universal rolling under the condition that the rolling reduction of the abdominal part S2 is larger than the rolling reduction of the head S1, regardless of the magnitude of the rolling reduction between the head S1 and the foot S3. It was confirmed that the bending in the left-right direction was large. That is, it is necessary to make the reduction rate of the head S1 equal to or higher than the reduction rate of the abdomen S2. Thereby, a stable universal rolling with few bending in the left-right direction can be realized. However, when the rolling reduction of the abdomen S2 is excessively smaller than the rolling reduction of the head S1, the abdomen S2 is stretched by tension due to the stretching of the head S1, so that rolling may become unstable. . For this reason, it is desirable that the reduction ratio difference obtained by subtracting the reduction ratio of the abdominal part S2 from the reduction ratio of the head S1 is less than 15%.

<Modification>
Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the claims encompass these modifications and embodiments that fall within the scope and spirit of the present invention.

For example, in the above embodiment, the shape steel is the rail S, but the present invention is not limited to such an example. For example, a shape steel having a shape other than the rail may be used. In this case, the cross-sectional shape perpendicular to the longitudinal direction is formed on the web extending in one direction, the first flange (short side flange) formed at one end of the web, and the other end of the web. The shape needs to have a second flange (long side flange) wider than the first flange. In addition, the web, the 1st flange, and the 2nd flange in this shape steel are equivalent to the abdominal part S2, the head part S1, and the foot part S3 in the rail S, respectively.
Moreover, in the said embodiment, in the rolling equipment, the finish rolling mill of the roll structure different from the universal rolling mill 1 is provided further downstream of the universal rolling mill 1 and the forming rolling mill, and the finish rolling of the rail S is performed by the finishing rolling mill. May be performed.

<Effect of embodiment>
(1) A method for manufacturing a shaped steel according to one aspect of the present invention includes a web having a cross-sectional shape perpendicular to the longitudinal direction extending in one direction, a first flange formed at one end of the web, and other webs. When manufacturing a steel having a shape formed at the end and having a second flange wider than the first flange, the reduction rate of the first flange is larger than the reduction rate of the second flange; and Universal rolling is performed under the condition that the reduction ratio of the first flange is equal to or higher than the reduction ratio of the web.

According to the configuration of (1) above, since the reduction ratio of the sheet thickness at the three locations of the web and the first and second flanges in the universal rolling is set in an appropriate range, it is possible to suppress bending in the left-right direction. It becomes. Furthermore, since bending in the left-right direction is suppressed, universal rolling can be performed stably, and productivity can be improved. Moreover, according to the structure of said (1), the rolling in the state shifted | deviated to the left-right direction in subsequent rolling can be prevented by suppressing the bending in the left-right direction, and a cross-sectional shape with a high dimensional accuracy is obtained. be able to. Thereby, the defect rate by the defect of a cross-sectional shape can be reduced, and a shaped steel can be manufactured efficiently.

(2) In the method for manufacturing a shape steel of (1), the difference in rolling reduction obtained by subtracting the rolling reduction of the second flange from the rolling reduction of the first flange is set to 8% or less.
According to the configuration of (2) above, universal rolling can be performed more stably, so that the smoothness of operation can be improved.
(3) In the method for manufacturing a shape steel of the above (1) or (2), a rolling reduction difference obtained by subtracting the rolling reduction of the web from the rolling reduction of the first flange is less than 15%.
According to the configuration of (3) above, universal rolling can be performed more stably, so that the smoothness of operation can be improved.

(4) In the method for manufacturing a shape steel according to any one of (1) to (3) above, the shape steel is equivalent to the web, the first flange and the second flange, and the abdomen S2, the head S1, and the foot S3, respectively. Rail S to be used.
According to the configuration of (4) above, in the rolling of the rail S having a left-right asymmetric shape, it is possible to suppress bending in the left-right direction.

Next, examples performed by the present inventors will be described. In the example, the rail S which is a shape steel left-right asymmetric like the said embodiment was manufactured, and the universal rolling mill 1 shown in FIG. 1 was used by intermediate rolling. And the rolling reduction of the head S1, the abdominal part S2, and the foot | leg part S3 was changed in the universal rolling of intermediate rolling, and the bending and cross-sectional shape of the manufactured rail S were evaluated. Regarding the cross-sectional dimensions of the rail S before universal rolling, the width A of the head S1 was about 90 mm, and the width B of the foot S3 was 160 mm. The width of the rolled material was about 220 mm. Furthermore, universal rolling was performed in the same manner for the comparative example in which the rolling reduction condition was different from that of the above embodiment, and the bending and the cross-sectional shape were evaluated.

Table 1 shows the conditions of reduction ratio and reduction ratio in Examples and Comparative Examples, as well as evaluation of bending, good / bad cross-sectional shape, and comprehensive evaluation. In Table 1, the “head-foot” is the difference between the reduction of the head S1 and the reduction of the foot S3, and the “head-abdomen” is the reduction of the head S1. This is the difference in rolling reduction obtained by subtracting the rolling reduction of the abdominal part S2 from the rate. In the evaluation of the bend, the bend was judged in three stages of “large”, “medium”, and “small” based on the amount of bending in the left-right direction. In the evaluation of whether the cross-sectional shape is good or bad, the cross-sectional shape of the manufactured rail S was measured and judged in three stages, “◯”, “Δ”, and “×”. The judgment criteria for bending are `` Small '' when it is almost straight when viewed from the front, `` Medium '' when there is a bending but there is no problem with rolling, and `` When there is a bending and there is a risk of jumping out of the line '' "Large". The criteria for determining the cross-sectional shape are “◯” when there is no problem in the shape, “△” when a slight defect occurs, and “X” when a clear defect (flange collapse, etc.) occurs. It was. In the comprehensive evaluation, the bending evaluation is “medium” or “small”, and the evaluation of the cross-sectional shape is “O”, and the evaluation of the bending is made when the cross-sectional shape evaluation is other than “O”. Was “small” for an acceptable condition (Δ), and other conditions were evaluated as poor (×).

As shown in Table 1, it was confirmed that the bending in the left-right direction was relatively small under any of the conditions of Examples 1 to 7. In Examples 1 to 6, in which the rolling reduction difference between the head S1 and the foot S3 is 8% or less and the rolling reduction difference between the head S1 and the abdominal part S2 is less than 15%, It was also confirmed that the cross-sectional shape was satisfactory to the extent that there was no problem. On the other hand, under the conditions of Comparative Example 1, Comparative Example 3, and Comparative Example 4, excessive bending occurred in the left-right direction. Further, under the conditions of Comparative Examples 1 to 4, bending in the right and left direction was generated at the “medium” level or higher, and the dimension of at least one portion after rolling was defective.
As described above, according to the present invention, bending in the left-right direction can be suppressed. Furthermore, by limiting the reduction rate difference between the head S1 and the foot S3 and the reduction rate difference between the head S1 and the abdomen S2, dimensional accuracy can be ensured satisfactorily. For this reason, the target shape steel product can be manufactured stably and efficiently.

DESCRIPTION OF SYMBOLS 1

Universal rolling mill

2a, 2b Horizontal roll 3 1st roll 4 4 2nd roll S rail (section steel)
S1 head S2 abdomen S3 foot

Claims

A cross-sectional shape perpendicular to the longitudinal direction has a web extending in one direction, a first flange formed at one end of the web, a second flange formed at the other end of the web, and wider than the first flange. When manufacturing a shape steel having a shape with two flanges,
Universal rolling under the condition that the reduction rate of the first flange is larger than the reduction rate of the second flange, and the reduction rate of the first flange is equal to or higher than the reduction rate of the web. Steel manufacturing method.
2. The method for producing a shape steel according to claim 1, wherein a difference in rolling reduction obtained by subtracting the rolling reduction of the second flange from the rolling reduction of the first flange is 8% or less.
The method for producing a shape steel according to claim 1 or 2, wherein a difference in rolling reduction obtained by subtracting the rolling reduction of the web from the rolling reduction of the first flange is less than 15%.
4. The rail according to any one of claims 1 to 3, characterized in that the shape steel is a rail in which the web, the first flange, and the second flange correspond to an abdomen, a head, and a foot, respectively. A method for producing the shape steel described.