JP3864606B2 - Rolling method of rough steel slab for H-section steel and shaping hole mold thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a rolling method of a rough slab for H-section steel and a shaping hole mold used in the rolling, and particularly relates to a shaping rolling technique for a coarse slab when producing a large H-section steel.
[0002]
[Prior art]
In general, as shown in FIG. 4, hot rolling of H-section steel is performed by using a rough mill 22, a rough universal mill group 23, an intermediate universal mill group 24, and a finishing universal mill 25, as shown in FIG. Done. In particular, in the case of a large H-section steel, rolling uses a slab 20a having a cross-sectional shape in FIG. 5 (a) or a H-section steel slab (beam blank) 20b having a cross-sectional shape in FIG. 5 (b). When a slab 20a is used as shown in FIG. 6, the upper and lower rolls of a rough mill in which a plurality of vertically symmetrical box hole molds 31 to 33 and one or a plurality of modeling hole molds 34 are engraved. In 2 and 3, it is shaped into the shape of a predetermined rough shape steel piece 40 for H-section steel. In FIG. 6, reference numerals 35 to 37 are protrusions for interrupting the slab short side.
The rough shaped steel slab 40 formed by the coarse mill is subjected to multiple passes of reciprocating rolling in the coarse unibar mill group 23 in FIG. 4 and then in the intermediate universal mill group 24, and then the finished unibar mill 25. Is formed in one pass and rolled into an H-section steel.
[0003]
In such a rolling process of the H-section steel, if the product dimensions are determined, the roll dimensions of the finishing universal mill and the roll dimensions of each rolling mill before the finishing universal mill are determined. That is, the web equivalent part width W1 during modeling rolling shown in FIG. 7A, the web equivalent part width W2 during rough rolling shown in (b), the web equivalent part width W3 during intermediate rolling shown in (c), and In general, it is designed so that the web-corresponding portion width W4 and the like during finish rolling shown in FIG. Therefore, when the dimensions of the product, especially the web equivalent width W4 in FIG. 7 (d), are changed, it is usually necessary to change the horizontal roll dimensions of each rolling mill in addition to the rough mill shaping hole mold. Will occur.
The method of determining such dimensions is the same in rolling large H-section steel using slab as a raw material, and the web equivalent part width in the forming hole mold of the coarse mill is the same as the web equivalent part width (inner web width) of the product. The dimensions are almost the same.
[0004]
In the rolling of large H-section steel, as described above, the steel piece 30 after edging is rolled by a plurality of times or a reciprocating pass over 10 passes or more with a vertically symmetrical shaping hole die 34, and a predetermined H shape is obtained. Since it is necessary to form into the shape of the rough steel piece 40 for steel, an overfill 45 is generated on the side surface of the flange due to the widening 44 due to the web reduction of the hole type as shown in FIG. In general, when rolling is performed continuously, the material is pressed against the rolled material, and as shown in FIG. 8B, it becomes a ridge 46 and remains as a product defect. In order to prevent this, it is necessary to perform a break-in edging with a box hole mold in the middle of modeling rolling, and in order to do so, the rolled material must be rotated 90 °, with an increase in the number of passes, This results in a significant increase in idle time between each path. Moreover, since the temperature of a rolling material also falls by it, rolling conditions will worsen also with respect to rolling after a rough mill.
[0005]
[Problems to be solved by the invention]
In rolling of conventional H-section steels, particularly large H-section steels using slabs, there are problems as listed below.
[0006]
(1) For example, in the case of a large H-shaped steel such as H800 × 300, H900 × 300, H400 × 400, H500 × 500 having a wide flange width, a thickness of 200 to 300 mm, a width of about 1400 to 1500 mm, or more Using a wide slab, as shown in Fig. 6, the bottom of the box hole type is flat, or a protrusion is carved into the bottom of the box hole type, and edging is performed while interrupting the short side of the slab, and the flange Although a method for forming the corresponding portion 38 is generally known, there is a case where a slab having a width that is originally required cannot be used in terms of restrictions on equipment. For example, when the upper and lower roll opening of the coarse mill is small, when trying to roll a slab of the width that is originally required, the roll diameter, especially the diameter of the hole bottom must be reduced, the rolling load, the roll strength, etc. As a result, the result cannot be rolled.
[0007]
(2) When a large H-shaped steel is rolled using a narrow slab, the amount of slab edging by the box hole mold is generally the same as or slightly narrower than the width of the molding hole mold. 9A, when the width is narrow and the edging amount is small as shown in S2 with respect to the originally required slab width S1 as shown in FIG. 9A, the flange after completion of edging as shown in FIG. 9B. The height h and the thickness t will be insufficient. Therefore, it is impossible to fill the flange-corresponding portion 38 even by rolling with a shaping hole mold, and as a result, a shape with a large underfill 47 is generated as shown in FIG. 9C. Therefore, it becomes impossible to make a product without problems by rolling after the coarse mill.
[0008]
(3) In modeling rolling performed after box rolling (edging), the reduction of the web surface is mainly performed, and the slab width of 200 to 300 mm is reduced to a web thickness suitable for universal rolling performed next. This reduction on the web surface has two actions: stretching the rolled material in the longitudinal direction (stretching) and expanding the width of the rolled material (widening). The central portion excluding the front and rear ends of the rolled material is the web reduction. Since the flange portion is drawn by stretching due to stretching, overfilling to the outer surface of the rolled material flange does not occur, but the leading and trailing end portions of the rolled material as shown in FIG. On the contrary, the influence of the widening 44 becomes strong, and the flange portion of the rolled material is pushed down by the side wall of the hole-type flange portion, so that the overfill 47 is likely to occur.
In order to prevent this, it is only necessary to perform one or more break-in edging with a box hole mold during modeling rolling to prevent the molding hole mold from being pushed down on the flange side wall. The idle time between the passes is greatly increased, and the temperature of the rolled material is lowered accordingly. Therefore, the rolling conditions are deteriorated even for rolling after the rough mill. Further, at the time of break-in, as the web thickness is reduced, as shown in FIG. 10, the web buckling 48 or the collapse 49 of the rolled material occurs, and there is a risk that the rolling cannot be continued.
[0009]
In Japanese Patent Publication No. 58-37042, as proposed for preventing these problems and performing stable rolling, the metal flow of the material is not applied to the flange side wall with a hole mold at the side of the flange of the rolled material during modeling rolling. Although the technology to introduce the flange from the web has been introduced, in this case, there is no restriction of the rolled material by the all-pass co-hole type side wall at the time of shaping rolling, so the stability at the time of rolling is poor, and H after the shaping rolling is completed There is a possibility that the entire width (web height) of the rough shaped steel slab for shape steel changes depending on the rolling reduction, temperature, material, etc., and there is a problem that the dimensional accuracy of the product is lowered during actual rolling. As a measure for improvement, Japanese Patent Publication No. 2-14121 discloses a method in which a metal flow from a narrow slab is actively performed from the web to the flange side by making the shaped hole type web surface a curved surface. In addition, it is possible to secure stability by restraining the flange side surface with a hole mold. However, although the width spread due to web reduction is weaker than that of the conventional method, it is difficult to eliminate the occurrence of overfill 47 at the trailing end of the rolling destination.
[0010]
The present invention has been made to solve the above-described problems, and in the case of forming and rolling a rough steel slab for H-section steel from a slab of a material, the rolling stability is good and product defects are generated. An object of the present invention is to provide a method for rolling a rough steel slab for H-section steel that can be shaped and rolled without making it, and a shaped hole mold used for the shaped rolling.
[0011]
[Means for Solving the Problems]
The first rolling method of the rough shaped steel slab for H-section steel according to the present invention is the method of shaping and rolling the rough shaped steel slab for H-shaped steel from the slab of the material by a box hole mold and a modeling hole mold, Forming hole mold in which the hole web surface is flattened without changing the entire width of the hole mold, and the width corresponding to the hole web, which is the width of the hole web surface, is 50 to 200 mm narrower than the inner web width of the product. Is characterized by forming and rolling a rough shaped steel slab for H-section steel.
[0012]
The width of the perforated web surface that reduces the plate thickness of the slab (the width corresponding to the perforated web) is generally used for a perforated mold that forms a rough steel slab for H-section steel using a slab produced by continuous casting. In the universal rolling after modeling rolling, an extra portion is formed from the flange to the web accompanying the widening of each pass in the universal rolling after modeling rolling. . This surplus portion has the same function as the metal flow by the curved surface provided on the web surface of the shaping hole type disclosed in Japanese Examined Patent Publication No. 2-14121, and at the time of universal rolling performed after rough rolling, this surplus portion The metal flow from the web to the flange by rolling down increases the restraining force of the flange part, and in order to stabilize the formability and dimensional shape, especially in the case of large H-section steel, etc. become. However, when the width corresponding to the perforated web of the modeling hole mold is narrowed beyond 200 mm, the surplus portion generated due to the above-mentioned widening becomes excessive, and the biting performance is deteriorated and the number of passes is reduced during the next universal rolling. It is not appropriate because it tends to cause quality increase due to an increase or excessive reduction of the surplus part, and it is not appropriate, and the rolling of only the center part of the web increases during modeling rolling in rough rolling. There is a possibility that the balance of the growth of the balance is not balanced and trouble may be caused.
[0013]
In general, the width of the edging completion material to be subjected to modeling rolling is substantially the same as the width of the modeling hole mold. However, in rolling by the modeling hole mold according to the present invention, the edging amount by the box hole mold is set to the modeling hole mold. To the limit of the perforated web equivalent part width (for example, in the case of a modeling perforation with a perforated web equivalent part width narrowed by 100 mm, the edging amount can be increased to 100 mm as compared with the conventional). Not only does it impair stability during modeling and rolling. This is because the web surface of the rolled material can be preformed by performing light reduction rolling approximately the same as the slab thickness or about 10 mm at the initial stage of modeling rolling, and then rolling by actual reduction can be performed. This is because the flange side face does not hit the side wall of the shaping hole mold in the initial stage, but after pre-rolling, the web is widened to hit the hole side wall and restrained. Therefore, according to the first rolling method, the edging amount in the box hole mold can be increased even if the slab having the same width as the conventional one is used, so that it is extremely effective when the width and thickness of the flange are required. is there. In addition, when the width and thickness of the flange are not so great depending on the rolling size, it is possible to reduce the width of the slab as a raw material, in other words, to reduce the amount of edging (including reduction of the pass).
[0014]
Second rolling method of H-shaped steel for rough shaped steel strip of the present invention, further, the radius 100 originating from the inside of the grooved flange corner away 10~30mm than the caliber full width of the shaped grooved The rough shape steel slab for H-section steel is shaped and rolled by a shaping hole mold provided with a 500 mm hole-shaped arc portion.
[0015]
The total width of the shaping hole mold is roughly determined by a value obtained by adding the thickness of the flange (both flange thicknesses) necessary for universal rolling to the inner width of the product web. In the method, as described above, in order to suppress overfilling at the time of modeling rolling that is likely to occur at the front and rear end portions of the rolled material, the corners of the hole mold flanges that are 10-30 mm away from the entire width of the mold hole mold are started. Since it is a modeling hole mold provided with a hole arc portion having a radius of 100 to 500 mm, the restraining force of the side face of the rolled material flange by this modeling hole mold is weakened by the arc portion, thereby reducing the material pressing during rolling. The occurrence of overfill can be suppressed, break-in edging, which was necessary in the past, is no longer necessary, and the number of passes can be reduced. Further, since the material flange portion is not pushed down by the side wall of the modeling hole mold, the material can easily enter the flange width direction, and the formability in modeling rolling is improved.
[0016]
The modeling hole mold used in the first and second rolling methods of the present invention is a modeling hole mold used in the final step of modeling rolling of the H-shaped steel rough steel slab without changing the full width of the hole mold. The radius corresponding to the mold web is about 50 to 200 mm narrower than the web inner width of the product that is generally required, and the radius is 100 to 50 mm starting from the inner corner of the mold flange that is 10 to 30 mm away from the full width of the mold. It has a 500 mm hole arc portion.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross-sectional shape of a shaped hole mold according to the present invention and a cross-sectional shape of a rough steel slab for H-section steel produced by the shaped rolling. In addition, the broken line in a figure shows the shape of a prior art example.
The modeling hole mold 1 illustrated here has a cross-sectional shape which is formed in a circumferential groove shape symmetrically on the upper roll 2 and the lower roll 3 of the rough mill. The cross-sectional shape includes a hole-shaped flange outer surface 4, a hole It is formed from a continuous shape of the mold flange end surface 5, the hole mold inner surface 6, and the hole web surface 7. And, the perforated web corresponding portion width W corresponding to the perforated web surface 7 does not change the total perforated width W0 (the W0 dimension is the same as the conventional dimension), and the web of the product generally required. It is formed to be 50 to 200 mm smaller than the inner width. Further, the hole arc portion 8 corresponding to the inner surface 6 of the hole flange has a radius R starting from a hole flange corner portion 9 formed 10 to 30 mm inside the hole width W0. Is formed in an arc shape of 100 to 500 mm. The inner and outer hole-type flange corners 9 and 10 and the hole-type opening end 11 are each provided with an appropriate radius.
[0018]
The rolling of the H-section steel is carried out in a rolling facility having a mill arrangement as shown in FIG. In FIG. 4, 21 is a heating furnace, 22 is a rough mill, 23 is a rough universal mill group, 24 is an intermediate universal mill group, and 25 is a finishing universal mill. The modeling hole mold 1 used in the present invention is equipped in the rough mill 22 and used in the final process of modeling rolling.
Since the width W of the perforated web surface (web-corresponding portion) 7 of the modeling perforation mold 1 is made narrower than before in the case of modeling rolling, the amount of edging in the box perforations 31 to 33 shown in FIG. 6 is increased. As long as the edging amount is not increased beyond the value obtained by narrowing the web surface width, there will be no problems (such as poor biting) when performing molding and rolling. As shown in (b), the height h and thickness t of the flange-corresponding portion 41 are increased compared to the conventional case, and the width and thickness of the flange portion are required, including formability in modeling rolling. Very effective for size.
[0019]
In modeling rolling, after pre-forming at the initial stage of rolling, rolling is performed under actual pressure. Due to the widening of the material web portion due to rolling, a gap 13 is formed inside the hole-shaped flange portion 12 as shown in FIG. Will occur. However, this is because the hole-shaped web surface width has been reduced, and it can be said that this phenomenon is intentionally generated. In other words, this gap 13 needs to be generated in order to obtain a rough shaped steel slab 40 for H-section steel that can be rolled without problems in a universal mill as the next process. It is necessary to determine how much the width W of the perforated web surface 7 is reduced within a range of 50 to 200 mm in consideration of the edging amount from the edge. In designing the hole shape, the amount of reduction in the web surface width is determined with reference to the size and thickness of the rolling object, the width and thickness of the slab to be used, and the target edging amount, but it exceeds 200 mm as described above. If the width of the web surface is reduced, it becomes a problem during rolling in the universal mill, so care must be taken.
[0020]
When rolling is performed with the shaping hole mold 1 according to the present invention, the surplus portion 43 is generated at the base portion of the flange portion 41 and the web portion 42 as shown in FIG. This is because the flange portion 41 is pushed out in the direction of the hole side wall due to the widening of the web under pressure, so that the web unpressed lower portion remains. As shown in FIG. When rolling down in the mill, when the flange portion 41 of the material is rolled down by the upper and lower horizontal rolls 26, 27 and the eaves roll 28, an action of assisting the metal flow 44 in the flange width direction is generated by reducing the surplus portion. Therefore, it is extremely effective for large sizes such as H400 × 400 and H500 × 500, which have a large flange width and are not easy to secure and stabilize in rolling.
[0021]
As described above, the arc portion 8 provided on the inner surface 6 of the mold flange of the modeling hole mold 1 shortens the surface length where the material and the hole mold come into contact with each other by making the inner wall portion of the hole mold a gentle arc shape. This is a method of weakening the binding force of the material by the hole type. As a result, the overfill that occurred at the time of modeling rolling could be eliminated.
As described above, in the past, it was extremely difficult to roll a large H-section steel using a wide slab in terms of equipment restrictions, but the reduction of the width W corresponding to the web of the shaping hole mold 1 according to the present invention. With the accompanying increase in the edging amount in the box hole mold and the addition of the arc portion 8 to the inner wall of the molding hole mold, it has become possible to manufacture a large H-section steel from a narrow slab without generating wrinkles or the like. .
[0022]
【Example】
Examples of the present invention will be described below. In this embodiment, a modeling hole mold 1 shown in FIG.
Conventionally, when a product having a large flange width and a large thickness such as H400 × 400 or H500 × 500, such as H400 × 400 or H500 × 500, is rolled using a slab, it is engraved on a roll of a coarse mill as shown in FIG. Since it is necessary to perform edging in the slab width direction using a plurality of provided box hole molds 31 to 33 and to secure the width and thickness of the H-shaped steel flange equivalent part before shaping rolling, A slab of 300 mm and a width of 1400 to 1500 mm was required.
However, in the present invention, paying attention to the widening due to web reduction during modeling rolling, the edging amount even from a narrow slab by making the width narrower than the web surface width of the modeling hole mold generally required Therefore, even a slab having a width of 1300 mm can cope with a flange thickness of up to 80 mm. In addition, by utilizing the fact that the surplus portion 43 is generated from the web to the flange root due to the widening during shaping rolling, the flange width is insufficient and the plate thickness is poor (unevenness) which is likely to occur during rolling in the universal mill after the rough mill. The occurrence of meat, etc.) can also be prevented. Further, as an effect of the circular arc portion 8 provided on the side wall portion of the shaping hole as a measure for reducing wrinkles, a crimp-shaped wrinkle that has always occurred at the front and rear end portions of the rolled material at the center of the flange side surface of the conventional product. However, as a result of applying the present invention, none has been achieved.
[0023]
【The invention's effect】
As described above, according to the present invention, the forming hole mold is rolled by a forming hole mold whose width corresponding to the hole-shaped web of the forming hole mold is 50 to 200 mm narrower than the inner width of the web of the product that is generally required. Therefore, it is possible to perform stable forming and rolling of a rough slab for a large H-section steel without generating product defects even from a narrow slab. In addition, since a narrow slab can be used, rolling can be performed safely without problems in terms of rolling equipment restrictions, particularly roll strength problems resulting from restrictions on the opening degree of the upper and lower rolls of the coarse mill.
[Brief description of the drawings]
FIG. 1 is a diagram showing the cross-sectional shapes of a shaping hole mold and a rough steel slab for H-section steel according to the present invention.
FIG. 2 is a view showing a situation in which a surplus part is formed at the time of shaping rolling by the shaping hole mold of the present invention.
FIG. 3 is a diagram showing an effect of width expansion due to surplus portion reduction during universal rolling.
FIG. 4 is a layout diagram of rolling equipment.
FIG. 5 is a diagram showing material types.
FIG. 6 is a diagram showing a cross-sectional view of a box hole mold and a modeling hole mold in a rough mill and a rough rolling process using a slab.
FIG. 7 is a diagram showing widths corresponding to webs during modeling rolling, rough rolling, intermediate rolling, and finish rolling.
FIG. 8 is a diagram showing a state of occurrence of defects during conventional modeling rolling.
FIG. 9 is a diagram showing a situation of defects that occur when a slab width is short in a conventional rolling method.
FIG. 10 is a diagram showing a situation of defects that occur when a web is thin in a conventional rolling method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Modeling hole type | mold 2 Upper roll 3 Lower roll 4 Hole type | mold flange outer surface 5 Hole type | mold flange end surface 6 Hole type | mold flange inner surface 7 Hole type | mold web surface (web equivalent part)
8 Hole-type arc part 9 Hole-type flange corner part 10 Hole-type flange corner part 11 Hole-type opening part 12 Hole-type flange part 13 Gap 20a Slab 20b Beam blank 21 Heating furnace 22 Coarse mill 23 Coarse universal mill group 24 Intermediate universal mill group 25 Finishing Universal Mill 26 Upper Horizontal Roll 27 Lower Horizontal Roll 28 Collar Roll 30 Edging Finished Materials 31, 32, 33 Box Hole Type 34 Modeling Hole Type 35, 36, 37 Protrusion 40 Coarse Steel Piece 41 for H-Shaped Steel Flange 42 Web part 43 surplus part

Claims (3)

In the method of forming and rolling a rough shaped steel slab for H-section steel from a material slab by a box hole mold and a modeling hole mold,
The hole-shaped web surface was flattened without changing the hole width of the modeling hole mold, and the width of the hole-shaped web surface corresponding to the width of the hole-shaped web surface was reduced by 50 to 200 mm from the inner width of the product web. A method for rolling a rough shaped steel slab for H-section steel, comprising shaping and rolling a rough shaped steel slab for H-section steel using a shaping hole mold. Coarse shaped steel slab for H-shaped steel by a modeling hole mold provided with a hole arcuate part having a radius of 100 to 500 mm starting from the inner corner of the mold hole flange 10 to 30 mm away from the full width of the mold hole mold The method for rolling a rough shaped steel slab for H- section steel according to claim 1, wherein the steel is shaped and rolled. The shaping hole mold used in the final step of shaping rolling of the H-shaped steel rough shape slab flattenes the hole web surface without changing the hole width, and the hole diameter is the width of the hole web surface. The web-corresponding portion width is 50 to 200 mm narrower than the web inner width of the product, and has a hole arc portion having a radius of 100 to 500 mm starting from the inner hole flange corner portion 10 to 30 mm away from the hole width. A shaped hole mold of a rough steel slab for H-section steel, characterized in that.

Images