JP3769245B2 - Rough rolling method for H-section steel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rough rolling method for H-section steel, and in particular, large H-section steel with a web height or flange width exceeding 800 × 300 is efficient and inexpensive without using a particularly large material section or equipment. The rolling method to manufacture is provided.
[0002]
[Prior art]
For example, as shown in FIG. 9, a manufacturing process of a senior size H-section steel by hot rolling includes a double roughing mill 31 (hereinafter referred to as “rough rolling mill”), a pair of upper and lower horizontal rolls, and a pair of A first rough universal rolling mill group comprising a first rough universal rolling mill 32 having left and right side rolls, an edger rolling mill 33 disposed in the vicinity of the first rough universal rolling mill 32, and a second rough universal rolling The rolling machine is formed by a rolling device array composed of a second rough universal rolling mill group including a mill 34 and an edger rolling mill 35 disposed in the vicinity of the second rough universal rolling mill 34 and a finishing universal rolling mill 36. The
[0003]
As a material of the H-shaped steel, a slab or a beam blank that is generally manufactured by continuous casting is used. When the slab is used as a raw material, the roughing mill 31 is provided with edging hole molds 311 to 313 for reducing in the slab width direction and a shaping hole mold 314 for reducing the web thickness as shown in FIG. The dogbone steel piece 37 is formed by sequentially rolling down the short side of the slab with a plurality of passes from above and below by a plurality of passes by the edging hole molds 311 to 313 having protrusions at the center of the hole mold. At this time, the web inner method Hi is reduced to the outer web method Ho such that the inner method Hi is substantially equal to or slightly smaller than the inner width of the product. Further, the flange width of the dog bone steel piece 37, that is, the hole bottom width B of the third edging hole mold 313 is determined in consideration of the deformation amount of the flange in the shaping hole mold 314 and the universal rolling mill group.
[0004]
Next, the dog bone steel piece 37 is turned 90 ° or 270 ° to reduce the web thickness and shape the flange shape. Here, the inner width Wi and the outer width Wo of the shaping hole mold 314 are substantially equal to the inner web method Hi and the outer web method Ho of the dogbone steel piece 37, and the hole flange portion depth d is the product depth. The length is approximately equal to the length from the web surface to the flange tip (hereinafter referred to as “flange leg length”). The forming hole mold 314 performs reduction in a plurality of passes to form a rough steel piece 38 in which the ratio tf / tw of the flange thickness tf to the web thickness tw and the flange leg length L are substantially close to the product thickness ratio and the flange leg length.
[0005]
In the first and second rough universal rolling mills, the obtained rough shaped steel slab 38 is subjected to thickness reduction in a state in which the reduction ratio of the web and the flange is substantially balanced by the coarse universal rolling mill, and at the edger rolling mill. The flange width is reduced and the flange width and tip shape are shaped. Then, with respect to the material to be rolled which has been shaped to almost the product dimensions, the finishing universal rolling machine 36 makes the flange perpendicular to the web and finishes the thickness to the final dimension.
[0006]
Thus, depending on the product series of H-section steel, the approximate dimensions of the main parts of the H-section steel are almost determined by the roughing mill 31, and the cross-section of the dogbone steel piece 37 is determined from the deformation characteristics of the shaping hole mold. The dimensions are almost determined naturally. The flange width that can be formed by edging rolling is almost determined by the reduction amount in the slab width direction, that is, the difference between the slab width and the outer web method at the end of edging rolling, and the slab width is determined so that the required flange width can be formed by edging rolling. The
[0007]
In recent years, the needs for H-section steels with larger web heights and flange widths have increased with the increase in the height and span of buildings. In order to manufacture such H-section steels, For this reason, a larger slab width is required. Moreover, the dimension of each hole type | mold of the rough rolling mill 1 corresponding to a product dimension becomes large, and the roll trunk | drum length for arrange | positioning the required number of hole types becomes large.
[0008]
For example, in order to produce and roll an H-section steel with a web height of 1000 mm and a flange width of 400 mm by the above rolling method, a slab width of 1800 mm or more and a roll body length of a rough rolling mill of 3300 mm or more are required. In such a facility, the amount of roll lift and the length of the roll body are limited, and it is necessary to modify the facility. On the other hand, a so-called two-heat rolling is also possible, in which a batch mill is required or rough rolling is performed halfway, and then the rolls of the roughing mill are rearranged and reheated to roll the product. High cost and energy loss due to decrease in performance and fuel intensity, and increase in the number of rolls are major problems. As described above, it is difficult to produce an H-section steel having a large web height and a large flange width in a limited material section, roll body length, and number of hole types.
[0009]
In response to these problems, Japanese Patent No. 2534223 proposes a rolling method that expands the web height without reducing the web thickness with three or more shaping hole molds that share the web portion as shown in FIG. ing.
In Japanese Patent Laid-Open No. 2000-271601, a rough rolling material or continuous cast beam blank is shown in FIG. After passing through a roll having a plurality of hole types that share a part of the flange equivalent part, such as adjusting the flange shape and reducing the web thickness, the web height is increased or the web height is reduced, the flange A rolling method has been proposed in which at least one of the width reductions is performed.
[0010]
[Problems to be solved by the invention]
However, when the present inventors examined in detail about the widening rolling method of the in-web method in an experiment, the web height was widened by inserting into a hole mold having a larger inner width than the in-web method of the material to be rolled. In this case, generally, the web thickness of the crop portion is smaller than that of the steady portion, so that it is difficult to be crushed. As shown in FIG. Here, the central angle between the straight line m connecting the contact start portion 39 and the roll center O when the material to be rolled is caught and the straight line n vertically lowered from the roll center O is the bite angle ψ, The tangent angle between the material to be rolled and the hole mold is θ (the material to be rolled is locally deformed when it comes into contact, so it can be seen that it is almost equal to the inclination angle of the hole mold), and the direction of the friction force is the roll circumferential speed direction. In order for the material to be rolled to overcome the force pushed back by the roll and be drawn into the roll bite, the following equation is established from the relationship of the force in the rolling direction.
μPcosθ ・ cosψ> Psinθ ・ sinψ
ψ <tan ^-1 (μ / tanθ) (1)
In fact, it has been found that it becomes difficult to bite suddenly under conditions that exceed this angle.
[0011]
The in-web method represented by Japanese Patent Publication No. 55-30921, Japanese Patent No. 2534223, and Japanese Patent Laid-Open No. 62-50002 widens the in-web method from a small beam blank or coarse pressure material with multiple hole types. The conventional rolling method is intended for H-section steel with a conventional web height of up to about 900 mm and a flange width of 300 mm, that is, a flange leg length of less than 150 mm. Even if the portion and its peripheral portion are brought into contact with each other, the problem that the material does not bite into the roll does not occur because the biting angle is relatively small. However, in the case of a H-shaped steel with a wide flange having a web height of more than 800 mm to about 1200 mm and a flange width of 300 mm, that is, a flange leg length of more than 150 mm. Since the biting angle exceeds the rolling limit when they come into contact with each other, the in-web method widening amount per hole mold cannot be increased. In addition, when biting from the vicinity of the flange tip, the reduction of the flange width becomes large, so that it is difficult to secure the flange width with the H-shaped steel having a large flange width targeted by the present invention.
[0012]
In the technology described in Japanese Patent No. 2534223, there is no special idea in the web widening hole mold shape, and the web height is simply inserted through a hole mold larger than the in-web method of the material to be rolled without reducing the web thickness. If a large in-web widening is performed, the roll starts to come into contact with the flange tip side, the biting angle increases, and not only the biting becomes difficult, but the flange inner surface is lowered to the corner. It is easy to generate folds. For this reason, the amount of widening per hole mold is limited to a small number, and a large number of hole molds are required, or in order not to generate wrinkles, it is necessary to widen the web after making the web thickness very small. There is a problem that the extension length cannot be made sufficiently large, or that the rolling time for each rolling process varies greatly and efficiency is lowered. Moreover, it does not consider about manufacturing the product of a different flange width series by the same roll.
[0013]
In the technique described in Japanese Patent Application Laid-Open No. 2000-271601, in order to take a plurality of types of steps with the same roll, there is one in-web method widening hole mold disposed on the rough rolled material. In the example, the in-web widening amount is about 100 mm. Therefore, in order to manufacture a product having a large web height, it is necessary to use a beam blank or a slab having a large cross section in advance. Also in this case, when the slab is used as a raw material, there is a problem that a lump mill is necessary due to the roll lift restriction of the rough rolling mill, or two-heat rolling is caused due to the roll body length restriction. In addition, the inclination angle of the flange equivalent part in the first hole type is preferably set to 20 ° or more with respect to the flange length direction. This is because the flange inclination is reduced when the web height is reduced in the third hole type. This is to prevent wrinkles such as folding due to an increase in the flange thickness when the angle is reduced and the flange width is reduced with the fourth hole mold. That is, nothing is mentioned about the conditions related to the in-web method widening rolling, and there is no special contrivance.
[0014]
The present invention breaks through such problems and limitations of the prior art, and provides a rough rolling that efficiently and inexpensively produces a product with a large cross section within the limited slab width, beam blank cross section and rolling equipment that can be used at present. A method is provided.
[0015]
[Means for Solving the Problems]
That is, the present invention provides a method for rough rolling of an H-section steel in which the in-web method is wide-rolled by a hole mold, and the inclination angle of the inner surface with respect to the vertical line of at least one wide-hole hole mold is measured before rolling with the hole mold. It is a rough rolling method for H-section steel, characterized in that it is formed smaller than the flange inclination angle of the rolled material and is subjected to in-web widening rolling.
[0016]
Further, according to the present invention, in the rough rolling method of the H-section steel in which the in-web method is sequentially widened by a plurality of hole molds, the inclination angle of the inner surface of the hole mold with respect to the vertical line is formed larger than the flange inclination angle of the material to be rolled. After rolling with the first hole mold, expanding the flange inclination angle and widening the in-web method, the inclination angle of the inner surface with respect to the vertical line of at least one wide hole mold is the same as that before rolling with the hole mold. It is a rough rolling method for H-section steel, characterized in that it is formed smaller than the flange inclination angle of the rolled material and is subjected to in-web widening rolling.
[0017]
In addition, in order to perform large in-web method widening, a thickened portion is provided in the area from the web periphery to the corner of the material to be rolled in the in-web widening rolling or in the center of the web, and the thickened portion is reduced. However, the method is characterized by carrying out in-web widening rolling.
Furthermore, the present invention provides a method for forming an in-web method with a widened hole mold after forming a rough steel slab having a smaller in-web method than the in-web method of the product by an edging hole mold and a shaping hole mold arranged in a rough rolling mill. In the rough rolling method of H-section steel for widening rolling, the edging hole mold is formed into a shape having a protrusion in the center of the hole bottom, and the flange is formed by reducing the roll in the web height direction of the rolled material. The H-section steel is characterized by forming a thickened portion in the region from the corner portion to the corner portion or in the central portion of the web, and then rolling in the web by expanding the thickened portion with the in-web widened hole mold. It is a rough rolling method.
[0018]
And in order to produce different flange width series and thickness H-shaped steel from the same roll, the web thickness for finishing rolling with the shaping hole mold is changed according to the flange width or flange thickness of the product, A rough rolling method for H-section steel, characterized in that the thickness of the web is reduced while expanding the in-web method with a hole mold.
Alternatively, when at least two or more hole molds having different flange depths from the hole inner web method are arranged and rolled with a large flange width, when rolling with a hole mold with a small flange depth. After in-web widening rolling with a gap between the web and the hole mold, in-web widening rolling is performed while rolling down the uncompressed lower part of the corner with a hole mold having a large flange depth. When rolling a small size, after rolling with a hole mold with a small flange depth, contact the web with the hole mold and perform flange width reduction and in-web widening rolling, then a hole mold with a large flange depth. In this method, the in-web widening rolling is performed without reducing the flange width. Therefore, the flange part depth of one or a plurality of widening hole types is made smaller than the flange part depth of the final widening hole type.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail with reference to FIG. FIG. 1 shows that when a material to be rolled in the web smaller than the method in the web of the product is inserted and widened through a plurality of in-web widened hole molds, the inner width W of the hole mold is the in-web method of the rolled material. The drawing shows the state of biting when rolling through a hole mold that is larger than α by α. In this case, the inclination angle θ of the inner surface of the hole mold with respect to the vertical line (hereinafter referred to as “hole inclination angle”) θ is greater than the inclination angle of the inner surface of the flange of the material to be rolled (hereinafter referred to as “flange inclination angle”) δ. By making it smaller, the biting angle becomes smaller and the biting becomes easy even if the in-web method widening amount is larger than the limit widening amount when both the inclination angles are substantially the same. Moreover, since the amount of reduction in the vicinity of the corner portion is larger than in other parts, the metal is smoothly supplied in the web height direction, and in the steady portion, the web internal method increases on the roll bite entry side due to pre-deformation. The contact area on the inner side of the flange becomes smaller than the geometrical relationship, and it is difficult for the inner surface of the flange to be lowered. In addition, there is an effect of reducing the flange width reduction and rolling load. Although it is desirable to make the flange inclination angle δ larger by about 5 to 15 ° than the hole inclination angle θ, there is an effect before and after this.
[0020]
When performing in-web method widening with a plurality of hole molds, it is effective if the rolling is performed with at least one or more widened hole molds. Even when the rolling is performed with one or more hole molds, it is preferable to include a final widened hole mold. The reason for including the final widened hole mold is that after the flange inclination angle is reduced, the inclination angle is increased again, or when the inclination angle is kept small, the widening amount that can be widened by the single hole mold is reduced. Because. The relationship between the necessary widening amount and the hole shape may be determined in consideration of the above-described equation (1).
[0021]
FIG. 2 shows a hole arrangement and a hole shape when performing in-web method widening rolling with two hole molds. When the limit widening amount of the two-hole type is evaluated based on the relationship between the flange inclination angle of the material to be rolled and the hole inclination angle of each hole type, when the flange inclination angle δ of the material to be rolled 6 is small, as shown in FIG. A hole smaller than the hole inclination angle θ1 of the first hole mold 21 after the in-web widening rolling is performed with the hole inclination angle θ1 of the first hole mold 21 larger than the flange inclination angle δ of the material 6 to be rolled. Although rolling with the second hole mold 22 having the mold inclination angle θ2 has a smaller limit widening amount in the first hole mold, the second is due to the relationship between the bite angle and the occurrence of the lowering wrinkle inside the flange. It has been clarified that the limit widening amount in the hole type greatly increases and the total widening amount in the two hole type increases.
[0022]
The expansion of the flange inclination angle in the first hole mold is particularly effective when the flange inclination angle of the material to be rolled is smaller than about 20 °, and the flange inclination angle of the material to be rolled exceeds 20 ° in particular. In such a case, in-web widening rolling may be performed with the hole inclination angle smaller than the flange inclination angle of the material to be rolled even in the first hole mold.
[0023]
FIG. 3 shows the cross-sectional shape of the material 6 to be rolled according to the present invention and the contact area at the time of biting in the in-web widening rolling. Usually, a web crop is formed at the stage of in-web method widening rolling, and in order to increase the in-web method widening amount beyond the bite limit of the flange, as shown by shading 8 in FIG. The corner R of the web / flange boundary portion of the material 6 to be rolled is enlarged so that the reduction from the web peripheral portion to the corner portion starts before the contact (shaded portion 9 in the figure) near the flange inner end. In addition, a thickened portion 7 is provided so that the thickness gradually increases from the vicinity of the center to the end of the web, and the reduction is performed during the in-web widening. In general, the rolling limit angle after biting is larger than the limit angle at the time of biting, and the biting limit angle inside the flange can be increased when the material to be rolled is drawn into the roll bite by web reduction. By rolling down the thickened portion 7, there is also an effect that the internal web method is enlarged on the roll bite entry side by pre-deformation and the biting angle inside the flange is reduced. The appropriate amount of the thickened portion 7 from the corner R and the peripheral portion of the web to the corner portion may be determined by the targeted in-web widening amount.
[0024]
Moreover, the same effect is acquired even if the thickening part 10 is provided in the center part of a web like FIG. 4, or web thickness is reduced over the whole web. When a thickened part is provided at the center of the web and the inner web method is widened while this part is being reduced, the web reduction is performed in the stationary part while a tensile force is applied in the web height direction by the inner web method. Therefore, there is an effect that the metal at the center of the web moves in the web height direction and the widening of the web inner method becomes easy.
Further, by performing multi-pass rolling in the same in-web method widened hole mold, the web inner method is expanded beyond the inner width of the hole mold in the second pass and the subsequent in-web inward widened hole mold is bitten. It becomes easy.
[0025]
In a plurality of in-web widening hole molds, the hole corner R is gradually reduced, or the hole shape corresponding to the portion from the web peripheral part to the corner R part is gradually flattened, or By performing both of them, if the above-mentioned thickened portion is stepped down by the in-web method widening hole type, the effect is obtained in all widening rolling, and the total widening amount is further increased.
[0026]
FIG. 5 shows a typical example of a rolling device array to which the present invention is applied when a slab is used as a material. In this case, the first rough rolling mill 1, the second rough rolling mill 2, the rough universal rolling mill 3, the edger rolling mill 4 and the finishing universal rolling mill 5 are configured. The above-mentioned in-web method widening rolling is performed by the second roughing mill 2. An example of the hole type of each roughing mill is shown in FIG. In the 1st rough rolling mill 1, first, a slab is crushed in the width direction by the edging hole molds 11 to 13 having the protrusions 11a to 13a at the center of the hole bottom, a flange is generated, and a dog bone steel piece is obtained. At that time, in order to secure the flange thickness corresponding to the large H-section steel, rolling is performed until the portion corresponding to the in-web method becomes smaller than the in-web method of the product. At this time, if the widths A2 and A3 of the bottoms of the protrusions in the edging hole molds 12 and 13 are increased within a range not exceeding the thickness of the slab, the flange generation efficiency is increased. Next, the web thickness is reduced with the shaping hole mold 14 to form a rough steel slab, and the inner width W of the shaping hole mold 14 is set to be approximately equal to or slightly larger than the web inner method of the dog bone steel slab. The part 15 from the part to the corner part is composed of a plurality of arcs and straight lines and has a gently inclined shape. By these effects, when the web thickness is reduced, the shrinkage of the flange is suppressed, and a sufficient flange thickness can be secured.
[0027]
Subsequently, two in-web method widening hole molds similar to those in FIG. 2 described above are arranged in the second rough rolling mill 2, and in-web method widening rolling is sequentially performed. Here, when the flange inclination angle of the rough steel slab is small, the first widened hole mold 21 in which the hole inclination angle θ1 is larger than the flange inclination angle of the rough steel slab formed by the first rough rolling mill 1, In-web widening rolling is performed while rolling down the thickened part. Subsequently, in the second widened hole mold 22, large in-web method widening rolling can be performed by performing the in-web method widening rolling with the hole inclination angle θ 2 smaller than that in the first widened hole mold 21. This makes it possible to manufacture an H-shaped steel product having a large web height and flange width in one heat from a slab having a relatively small cross section.
[0028]
Moreover, if the web thickness which complete | finishes rolling with the 1st rough rolling mill 1 is enlarged, when the web internal method is widened with the 2nd rough rolling mill 2, the amount of flange wall shrinkage will become large, and the 1st with a large hole-type inclination angle. By continuously reducing the web thickness with the widened hole mold 21, the amount of flange wall shrinkage increases. On the contrary, if the web thickness at which the rolling is finished with the first roughing mill is reduced, the flange thickness of the rough shaped steel slab is relatively increased, and the flange is also increased when the inner web method is widened with the second roughing mill. The amount of meat shrinkage decreases. By controlling the web thickness at the end of rolling in the first roughing mill in this way, series with different flange widths and large H-section steels with a wide ratio of flange thickness to web thickness are manufactured from the same roll. can do.
[0029]
When a continuously cast beam blank or a rough rolled rough shape is heated and manufactured, the second rough rolling machine in FIG. 5 is omitted, and in-web widening is performed by the first rough rolling machine. Of course, by using both the first rolling mill and the second rough rolling mill, the enlargement of the flange inclination angle and the widening of the in-web method can be repeated, so that the in-web method can be further expanded. It becomes possible to manufacture H-shaped steel products having a large height and flange width.
[0030]
The above has been described with an example of up to two in-web widening hole molds, but it goes without saying that more than three in-web method widening hole types are more effective. For example, due to the roll body length restriction, even when the web part and the flange part are shared with each other as shown in FIG. Is a first hole mold 21 in which a thickened part is provided from the web peripheral part to the corner part, and the hole inclination angle is larger than the flange inclination angle of the material to be rolled. Increase in width and web widening rolling, and then in-web method widening rolling with the second hole mold 22 and the third hole mold 23 gradually decreasing the hole inclination angle, the biting property and the inside of the flange It is possible to perform rolling while increasing the amount of widening per hole mold without causing the problem of the lowering wrinkles.
[0031]
In addition, as shown in FIGS. 8A and 8B, one or a plurality of hole types excluding the final hole type, in FIG. 8A, the flange portion depth D1 of the first hole type 21 is shown in FIG. ), The flange depth D2 of the second hole mold 22 is made smaller than the flange depths D2 and D3 of the final hole mold, respectively, and the roll gap is adjusted when performing in-web method widening rolling with the hole mold. Can control the amount of flange width reduction, and different flange width series H-section steel can be manufactured with the same roll.
[0032]
Specifically, the flange depth of the first hole mold of FIG. 8 (a) and the second hole mold of FIG. 8 (b) is made to correspond to the smallest series among the flange width series manufactured with the same roll, When the flange width is small, the flange width is greatly reduced, and when the flange width is large, a gap is provided between the web and the hole mold to increase the width in the web. In this case, the depth of the flange part of the final hole mold is made to correspond to the product with the largest flange width, and when rolling a small flange width size, the in-web widening rolling is performed without reducing the flange width. Do. On the other hand, when rolling a size having a large flange width, the in-web widening rolling is performed while rolling down the uncompressed corner portion with a hole mold having a small flange depth. In addition, when expanding the width of the flange with a large gap between the web and the hole mold, the corner of the material to be rolled is used to prevent generation of a freckle at the rolling boundary of the flange base. It is preferable to provide the front part with an inclined part having a height corresponding to the gap.
[0033]
Although the explanation was omitted, when rolling the web inner method stepwise with a plurality of in-web method widening hole molds, if rough rolling is finished with the intermediate widening hole mold and then rolling is performed with a universal rolling mill Needless to say, large H-section steels having different web heights can be produced by the same roll. In addition, when manufacturing a web height series in which the inner web method is in the middle of the wide hole mold, the roll gap of the bore body is reduced when the inner web widening rolling is performed with a larger hole mold than the inner method of the series. Is set to be larger than the web thickness, and the widening rolling is performed to the middle of the flange piece width, and the unrolled corner portion is reduced by the subsequent universal rolling mill group. This makes it possible to manufacture multi-series products with the same roll.
[0034]
【Example】
An example in the case of manufacturing an H-section steel having a large web height and a large flange width by the rough rolling method of the present invention will be described.
<Example 1>
Using a 1350 width × 250 slab as a raw material, a 900 × 400 series H-section steel was manufactured by the rolling process shown in FIG. The in-web method of the product is around 840mm. The hole arrangement of the first rough rolling mill and the second rough rolling mill is as shown in FIG. 6, and two in-web widening hole molds were arranged in the second rough rolling mill. The edging hole mold of the first rough rolling mill was used to reduce the web height to 880 mm, and the web thickness was reduced to 80 mm using a molding hole mold having an inner width of 540 mm. The flange inclination angle at this time was 23 °. A thickened portion composed of a plurality of rounds was provided from the periphery of the shaped hole type web to the corner portion. In this case, even in the first hole mold, the hole inclination angle is made smaller than the flange inclination angle of the material to be rolled, the first hole mold has an inner width W1 = 700 mm, the inclination angle θ1 = 18 °, and the second hole mold has an inner width. W2 = 820 mm and inclination angle θ2 = 13 ° were set. In each hole type, in-web method widening rolling was performed while reducing the increased thickness portion in the first pass, and subsequently the web thickness was reduced in 1 to 3 passes using the same hole type. Next, in the coarse universal rolling process, the web inner method was slightly widened, the flange angle and the plate thickness were shaped, and the finished universal rolling mill was used as the final product. As a result, it was possible to produce a good product without any biting failure, generation of flaws for lowering the threads, and excessive or insufficient flange thickness.
[0035]
<Example 2>
Using a 1500 width x 300 thickness slab as a raw material, a 1000 x 400 series H-section steel was manufactured. The product web internal law is around 940mm. The hole type arrangement of the first roughing mill and the second roughing mill is as shown in FIG. The web height was reduced to 980 mm with an edging hole mold of the first rough rolling mill, and the web thickness was reduced to 80 mm with a shaping hole mold having an inner width of 640 mm. A thickened portion composed of a plurality of rounds was provided from the periphery of the shaped hole type web to the corner portion. In this case, in the first hole type of the second roughing mill, the inclination angle is 5 ° larger than the flange inclination angle of the material to be rolled to widen the inner web method by 80 mm, and in the second hole type, the inclination angle is set to the first hole type. The in-web method was widened 180 mm by making it 10 ° smaller than the mold inclination angle. Other than that, rolling was carried out in the same manner as in Example 1, and a good product could be produced without the occurrence of biting defects, generation of fretting down flaws, excess or deficiency of the flange thickness.
Also, the web thickness at the end of rolling in the first roughing mill is set to 120 mm, and the width of the flange in the web is increased and the web thickness is reduced by the second roughing mill. 350 series H-section steel was manufactured. Furthermore, by reducing the flange depth of the first widened hole mold by 25mm compared to the flange width of the second widened hole mold and reducing the flange width with the first widened hole mold, the 1000x300 series can be formed. Also, it is possible to make 1000 × 400 series from the same roll.
[0036]
<Example 3>
1100 x 400 series H-section steel was manufactured using 1500 width x 300 thickness slabs. In the second rough rolling mill, three in-web method widening hole molds are arranged as shown in FIG. 7, and after the flange inclination angle of the material to be rolled is expanded by the first hole mold, the second and third hole molds are formed. The tilt angle was reduced. Further, in-web widening rolling was performed while stepping down the increased thickness portion in each hole mold. And when it was made into a final product by the rough universal rolling process and the finishing universal rolling mill, a good product could be manufactured.
In addition, when manufacturing the product demonstrated in Examples 1-3 using the beam blank made from continuous casting as a raw material, the beam blank of the substantially same dimension as the rough-shaped cross section manufactured with each 1st rough rolling mill should be prepared. For example, the first rough rolling step can be omitted and the web can be easily manufactured by in-web method widening rolling in the second rough rolling step of the embodiment.
On the other hand, when the slabs having the same dimensions as the above-mentioned examples are produced by the conventional in-web widening rolling method, the biting property becomes a problem, and the in-web widening amount per hole mold is limited to about 100 mm. In both cases, because of the restriction on the number of widening hole types that can be arranged in the second roughing mill, the required in-web method widening amount could not be ensured and the product could not be manufactured. As described above, in the prior art, the in-web method widening amount per hole mold was about 100 mm, but the technique of the present invention enables widening up to about 180 mm as in the embodiment, and the small number of holes We have widened the target in-web method by the number of types.
[0037]
【The invention's effect】
According to the present invention, an H-section steel having a large web height and a large flange width can be efficiently and inexpensively manufactured without using a particularly large material section or equipment.
[Brief description of the drawings]
FIG. 1 is an explanatory view of an in-web widening rolling method for H-section steel according to the present invention.
FIG. 2 is an explanatory diagram of an in-web widening rolling method using two hole molds according to the present invention.
FIG. 3 is an explanatory view of a cross-sectional shape and a biting state of a thickened portion according to the present invention.
FIG. 4 is a schematic view of a material to be rolled with a thickened portion formed at the center of the web.
FIG. 5 is a representative rolling device train of the present invention.
FIG. 6 is an explanatory view of a rough rolling method for H-section steel using a slab according to the present invention as a raw material.
FIG. 7 is a hole diagram of a roughing mill in which a number of in-web method widening hole molds are arranged.
FIGS. 8A and 8B are hole diagrams of a roughing mill for separately producing products having different flange widths.
FIG. 9 shows a conventional representative rolling device array.
FIG. 10 is an explanatory diagram of a conventional rough rolling method for H-section steel.
FIG. 11 is a hole diagram of a roughing mill in a conventional in-web widening rolling method.
FIG. 12 is a hole pattern diagram of a roughing mill that separates H-section steels having different web heights and flange widths.
FIG. 13 is an explanatory diagram of a state of biting inside the flange in the in-web method widening rolling.

Claims (8)

In the rough rolling method of H-section steel, in which the in-web method is widened by a hole mold, the inclination angle of the inner surface with respect to the vertical line of at least one wide hole mold is the flange inclination angle of the material to be rolled before rolling with the hole mold. A method of rough rolling of H-section steel, characterized in that the method is in- web widening rolling in a state where the hole mold starts to contact from the inside of the flange according to the relationship of formula (1) .
ψ <tan ⁻¹ (μ / tan θ) (1)
Here, the central angle between the straight line connecting the contact start portion and the roll center when the material to be rolled is caught and the straight line vertically lowered from the roll center is the bite angle ψ, the hole inclination angle θ, the friction coefficient μ. In the rough rolling method of H-section steel, in which the in-web method is sequentially widened and rolled by a plurality of hole molds, the first hole mold in which the inclination angle of the inner surface of the hole mold with respect to the vertical line is larger than the flange inclination angle of the material to be rolled. After rolling, expanding the flange inclination angle, and widening the in-web method, the inclination angle of the inner surface with respect to the vertical line of at least one wide hole mold is the flange inclination angle of the material to be rolled before rolling with the hole mold. A method of rough rolling of H-section steel, characterized in that the method is in- web widening rolling in a state where the hole mold starts to contact from the inside of the flange according to the relationship of formula (1) .
ψ <tan ⁻¹ (μ / tan θ) (1)
Here, the central angle between the straight line connecting the contact start portion and the roll center when the material to be rolled is caught and the straight line vertically lowered from the roll center is the bite angle ψ, the hole inclination angle θ, the friction coefficient μ. In the in-web method widening rolling, a thickened part is provided in the area from the periphery of the web to the corner of the material to be rolled or in the center of the web, and the in-web method is widened while rolling down the thickened part with the in- web method widening hole type. The rough rolling method for H-section steel according to claim 1 or 2, wherein the rolling is performed.   An H-shaped steel that is subjected to widening rolling in the in-web method using a widened hole mold after forming a rough steel slab having a smaller in-web method than the in-web method of the product by an edging hole mold and a shaping hole mold disposed in a rough rolling mill. In the rough rolling method, the edging hole mold is formed in a shape having a protrusion in the center of the hole bottom to reduce the rolled material in the web height direction to generate a flange, and the area from the web peripheral part to the corner part with the modeling hole mold Alternatively, after the thickened portion is formed in the center of the web, the in-web method widening rolling is performed while the thickened portion is being reduced by an in-web method widening hole mold. Rough rolling method.   The web thickness at which rolling is finished with the shaping hole mold is changed according to the flange width or flange thickness of the product, and the web thickness is reduced while the in-web method is expanded with the in-web method widening hole mold. The rough rolling method of the H-section steel according to claim 4.   In the rough rolling method for H-section steel, in which the in-web method is sequentially widened and rolled by a plurality of perforations, at least two perforations with different flange depths from the perforation in-web method are arranged to increase the size of the flange. In the case of rolling, when rolling with a hole mold with a small flange part depth, a gap is provided between the web and the hole mold, and then in-web widening rolling is performed, and then a corner part with a hole mold with a large flange part depth is provided. When rolling in the web while rolling down the uncompressed lower part of the web and rolling a small flange width, when rolling with a hole mold with a small flange depth, the web and the hole mold are brought into contact with the flange. A rough rolling method for H-section steel, characterized by performing in-web method widening rolling without reducing the flange width with a hole mold having a large flange depth after width reduction and in-web widening rolling.   If there are at least two hole molds with different flange depths from the inner diameter method of the hole mold and rolling with a large flange width, when rolling with a hole mold with a small flange depth, the web and hole After in-web widening rolling with a gap between the mold, in-web widening rolling while rolling down the uncompressed lower portion of the corner with a hole mold with a large flange depth, rolling to a smaller flange width When rolling with a hole mold with a small flange depth, contact the web and the hole mold to reduce the flange width and widen in the web, and then increase the flange width with a hole mold with a large flange depth. 6. The rough rolling method for H-section steel according to any one of claims 1 to 5, wherein in-web widening rolling is performed without reduction.   The rough rolling method for H-section steel according to claim 6 or 7, wherein the flange portion depth of one or a plurality of widened hole molds is made smaller than the flange depth of the final widened hole mold.

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