Manufacturing method for H-beams

Abstract

To perform flat molding rolling of a large-sized rough shape-material made possible by improving generation efficiency of a flange, while conquering the equipment problem such as a roll barrel length, in a flat molding rolling performed after edging-rolling.SOLUTION: An H-shaped steel manufacturing method comprises a rough rolling step, an intermediate rolling step and a finishing rolling step. The rough rolling step and the intermediate rolling step include: an edging rolling step of rolling-molding a rolled material into a prescribed substantially dog-bone shape; a flat rolling step of forming a protrusion part at a web part center by rotating, by 90° or 270°, the rolled material after completing the edging rolling step; and a protrusion part erasing step of erasing by pressing down the protrusion part. Therein, at least the protrusion part erasing step is performed by an intermediate universal rolling machine that performs the intermediate rolling step, and the flat rolling step includes a widening rolling step of performing an inner size widening on a web part of the rolled material after forming the protrusion part.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a manufacturing method for manufacturing H-shaped steel using a slab or the like having a rectangular cross-section as a raw material.

Background Art

[0002] When manufacturing H-shaped steel, a raw material such as a slab or bloom extracted from a heating furnace is shaped into a rough shape (a so-called dog bone-shaped rolled material) by a rough rolling mill (BD), and the thickness of the web and flange of the rough shape is reduced by an intermediate universal rolling mill. At the same time, width reduction, end surface forging, and shaping are performed on the flange of the rolled material by an edger rolling mill close to the intermediate universal rolling mill. Then, an H-shaped steel product is shaped by a finishing universal rolling mill.

[0003] In such a manufacturing method of H-shaped steel, when shaping a rough shape of a so-called dog bone shape from a slab raw material having a rectangular cross-section, after making an indentation in the slab end surface in the first pass of the rough rolling process, the indentation is widened or the depth of the indentation is increased in the second and subsequent passes, and a technique for eliminating the indentation on the slab end surface in the subsequent passes is known (see, for example, Patent Document 1).

[0004] In addition, in the manufacture of H-shaped steel, after so-called edging rolling for edging the end surface (slab end surface) of a raw material such as a slab, the rolled material is rotated 90° or 270°, and flat shaping rolling for reducing the web equivalent part is known. In this flat shaping rolling, while reducing the web equivalent part, the flange equivalent part is also reduced and shaped. However, in recent years, in view of the demand for large-sized H-shaped steel products, when using a large-sized raw material as the rolled material, in general flat shaping rolling, various problems such as elongation in the web height direction and deformation of the flange equivalent part may occur, and shape correction may be required. Specifically, there has been a concern about a phenomenon in which, as the web equivalent part is reduced, the web equivalent part extends in the longitudinal direction, and the flange equivalent part is also stretched in the longitudinal direction by the stretching, resulting in a decrease in the thickness of the flange equivalent part.

[0005] Regarding this type of planar rolling, for example, Patent Document 2 discloses a technique for selectively reducing the web portion, which involves creating an unrolled portion in the center of the web portion, then erasing the subsequently formed protrusion (corresponding to the raised portion of the present invention), and widening the web portion, thereby efficiently manufacturing large H-shaped steel beams. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-88501 [Patent Document 2] Japanese Patent Application Publication No. 57-146405 [Overview of the project] [Problems that the invention aims to solve]

[0007] As mentioned above, in recent years, with the increasing size of structures and other materials, there has been a demand for the manufacture of large H-beam products. In particular, there is a demand for products with wider flanges than conventional ones, as these flanges contribute significantly to the strength and rigidity of H-beams. In order to manufacture H-beam products with wider flanges, it is necessary to create rolled material with wider flanges than conventional materials from the rough rolling process.

[0008] However, in the technology disclosed in Patent Document 1, for example, there are limitations to widening the flange in a method that involves making incisions in the end face (slab end face) of a material such as a slab, edging the end face, and performing rough rolling using the resulting widening. That is, in conventional rough rolling methods, techniques such as wedge design (design of incision angle), reduction adjustment, and lubrication adjustment are used to improve the widening of the flange, but none of these methods contribute significantly to the flange width. Therefore, the widening ratio, which indicates the ratio of the amount of flange width widening to the amount of edging, is only about 0.8 even under the conditions where the efficiency in the initial stage of edging is highest, and under conditions where edging is repeated with the same hole type, it is estimated that this ratio decreases as the amount of flange width widening increases, and eventually reaches about 0.5. It is also conceivable to enlarge the material itself, such as a slab, and increase the amount of edging, but there are equipment limitations in terms of the size of the rough rolling mill and the amount of reduction, so there is a risk that sufficient widening of the product flange may not be achieved.

[0009] Furthermore, when manufacturing large H-beam steel products, large rough profiles are sometimes rolled and shaped during the rough rolling process. If large rough profiles are rolled and shaped using a method different from conventional methods, and the shape of the rough profile is made to be closer to that of an H-beam, then performing planar rolling using the technology described in Patent Document 2 above may cause problems such as elongation in the web height direction and deformation of the flange-equivalent portion.

[0010] In addition, when performing the planar rolling described above, it is conceivable that holes will be needed to remove the unrolled lower portion, and it is necessary to design the roll hole arrangement for engraving these holes. However, since the equipment used for rough rolling processes, including planar rolling, has equipment limitations such as roll shell length, it is not possible to perform a sufficient roll design, and two-heat rolling must be performed.

[0011] The inventors of the present invention have evaluated the flange thickness increase performance using a consistent process that includes a preceding process in which a recess is created in the web to generate an unpressed lower portion (a raised portion described later), and a subsequent process in which the unpressed lower portion is removed. Specifically, as will be explained in the embodiments of the present invention described later, for example, when using a 300mm thick slab as the material, they have found that the flange generation efficiency can be increased by setting the width of the unpressed lower portion to a width of 25% to 50% of the width of the web portion of the rolled material, leading to the present invention.

[0012] In view of the above circumstances, the object of the present invention is to provide a technology that improves the efficiency of flange formation while overcoming equipment problems such as roll shell length in flat rolling performed after edging rolling, and that enables flat rolling of large rough materials to efficiently and stably manufacture large H-beam steel products. [Means for solving the problem]

[0013] To achieve the above objective, the present invention provides a method for manufacturing H-shaped steel comprising a rough rolling step, an intermediate rolling step, and a finish rolling step, wherein the rough rolling step includes an edging rolling step in which the rolled material is rolled into a predetermined substantially dogbone shape, and a flat rolling step in which the rolled material is rotated by 90° or 270° after the completion of the edging rolling step to form a raised portion in the center of the web portion, the intermediate rolling step includes a raised portion removal step in which the raised portion is reduced and removed in an intermediate universal rolling mill, and in either or both of the flat rolling step and the raised portion removal step, a widening rolling step is performed to widen the inner width of the web portion of the rolled material. In the aforementioned flat rolling process, the raised portion is not reduced or removed. In the step of eliminating the raised portion, the vertical roll gap of the intermediate universal rolling mill is enlarged in accordance with the web height expansion due to the reduction of the raised portion, and rolling is performed to provide a method for manufacturing H-shaped steel. Furthermore, according to the present invention, a method for manufacturing H-shaped steel comprising a rough rolling step, an intermediate rolling step, and a finish rolling step, wherein the rough rolling step includes an edging rolling step in which the rolled material is rolled and shaped into a predetermined substantially dogbone shape, and a flat rolling step in which the rolled material is rotated by 90° or 270° after the completion of the edging rolling step to form a raised portion in the center of the web portion, the intermediate rolling step includes a raised portion removal step in which the raised portion is reduced and removed in an intermediate universal rolling mill, and in either or both of the flat rolling step and the raised portion removal step, a widening rolling step is performed to widen the inner width of the web portion of the rolled material. In the aforementioned flat rolling process, the raised portion is not reduced or removed. A method for manufacturing H-shaped steel is provided, characterized in that, in the step of eliminating the raised portion, the rolling process is carried out while keeping the vertical roll gap of the intermediate universal rolling mill constant.

[0014] The rolling process in the aforementioned raised portion removal step is performed in multiple passes, and in at least one of these passes, the rolling process may be performed with the inner surface of the flange of the material to be rolled in contact with the horizontal roll.

[0019] In the raised portion removal process, the roll opening of the vertical rolls of the intermediate universal rolling mill may remain constant until the removal of the raised portion is completed.

[0020] The width of the raised portion formed in the flat rolling process may be set to 25% to 50% of the internal width of the web portion of the rolled material. [Effects of the Invention]

[0021] According to the present invention, in flat rolling performed after edging rolling, it is possible to overcome equipment problems such as roll shell length, improve the efficiency of flange formation, perform flat rolling of large rough materials, and efficiently and stably manufacture large H-beam steel products. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram illustrating the manufacturing line for H-shaped steel. [Figure 2]It is a schematic explanatory diagram of the pass configuration of the rough rolling mill. [Figure 3] It is a schematic explanatory diagram of the fifth pass. [Figure 4] It is a schematic explanatory diagram showing the roll configuration of the intermediate universal rolling mill. [Figure 5] It is a schematic explanatory diagram when removing the raised portion in the intermediate universal rolling mill. [Figure 6] It is a graph showing the relationship between the escape rate and the increase / decrease rate of the flange width after forming the H-shaped rough material. [Figure 7] It is an explanatory diagram regarding the numerical values in Tables 6 and 7.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions are omitted.

[0024] (Schematic of the production line) FIG. 1 is an explanatory diagram of a production line L for H-shaped steel including a rolling facility 1 according to the present embodiment. As shown in FIG. 1, in the production line L, a heating furnace 3, a rough rolling mill 4, an intermediate universal rolling mill 5, and a finishing universal rolling mill 8 are arranged in order from the upstream side. Further, an edger rolling mill 9 is provided in the vicinity of the intermediate universal rolling mill 5. Hereinafter, for the sake of explanation, the steel material in the production line L will be collectively referred to as "rolled material A", and its shape may be appropriately illustrated using broken lines, slashes, etc. in each figure.

[0025] As shown in Figure 1, in the manufacturing line L, the rolled material, such as a slab 11, coming out of the heating furnace 3 is roughly rolled by the roughing mill 4, and then intermediate rolled in the intermediate universal rolling mill 5. During this intermediate rolling, the flange tip of the rolled material is reduced by the edger rolling mill 9 as needed. Typically, the rolls of the roughing mill 4 are engraved with 4 to 6 holes, and an H-shaped rough material 13 is formed by reverse rolling in multiple passes through these holes. The H-shaped rough material 13 is then similarly reverse-rolled in multiple passes using a rolling mill array consisting of the intermediate universal rolling mill 5 and the edger rolling mill 9 to form an intermediate material 14. The intermediate material 14 is then finish-rolled into the product shape in the finishing universal rolling mill 8 to produce an H-shaped steel product 16.

[0026] Here, the slab thickness of the slab 11 extracted from the heating furnace 2 is within the range of, for example, 230 mm to 310 mm, which is used in the manufacture of ordinary H-beams. The slab width is arbitrarily selected according to the flange width and web height of the product.

[0027] (Outline of the pore structure) Next, the hole configuration and hole shape of the roughing mill 4 shown in Figure 1 will be described below with reference to the drawing. Note that the heating furnace 3, finishing universal rolling mill 8, and edger rolling mill 9 in the rolling line L are common devices that have been used in the manufacture of H-beams for a long time, and their device configurations are known, so their description will be omitted in this specification. Furthermore, the rolling process in the intermediate rolling process at the intermediate universal rolling mill 5 will be described separately as the intermediate rolling process according to the present invention.

[0028] Figure 2 is a schematic diagram illustrating the die configuration of a roughing mill 4 that performs the roughing process, and is a schematic cross-sectional view of the die cut into the roughing mill 4. Although Figure 2 shows a case where four die cuts are cut into the roll of the roughing mill 4, this is just one example of a die configuration, and generally, a roughing mill roll has, for example, 4 to 6 die cuts. Also in Figure 2, the shape of the rolled material A (at the end of the first pass) formed in each die cut is shown by dashed lines.

[0029] As shown in Figure 2, the roughing mill 4 is equipped with a pair of horizontal rolls, an upper-hole roll 33 and a lower-hole roll 34, which are supported by the housing 30. Four holes K1, K2, K3, and K4 are engraved in the gap between these upper-hole roll 33 and lower-hole roll 34 (from left to right in Figure 2, these are holes K1, K2, K3, and K4). For the purposes of explanation, these holes will be referred to as the first hole K1, the second hole K2, the third hole K3, and the fourth hole K4 below. In typical roughing of H-beams, multi-pass rolling is performed in each of the first to fourth holes K4.

[0030] Although not shown in Figure 2, the roughing mill 4 is also provided with a hole mold in addition to the first to fourth hole molds K1 to K4, which transforms the rolled material A, which has been reduced in the fourth hole mold K4, into a so-called dogbone-shaped H-shaped rough material 13. This hole mold will be described separately with reference to Figure 3.

[0031] The first hole type K1 to the fourth hole type K4 are configured such that the groove bottom width of the hole type becomes progressively wider, with the groove bottom width B1 of the first hole type K1, the groove bottom width B2 of the second hole type K2, the groove bottom width B3 of the third hole type K3, and the groove bottom width B4 of the fourth hole type K4 increasing in this order (i.e., B1 <B2<B3<B4)。

[0032] Furthermore, projections are formed in the center of the bottom and top surfaces of each of the first to fourth hole types K1 to K4. Hereinafter, the projections formed on the bottom and top surfaces of the first hole type K1 will be referred to as projections 40, those formed on the bottom and top surfaces of the second hole type K2 as projections 41, those formed on the bottom and top surfaces of the third hole type K3 as projections 42, and those formed on the bottom and top surfaces of the fourth hole type K4 as projections 43. Each projection has a tapered shape, protruding upward from the bottom surface of the hole type and downward from the top surface of the hole type, and its dimensions, such as the length of the protrusion, are the same for the bottom and top surfaces. Here, the projection 43 of the fourth hole type K4 may be substantially flat and may have a function to flatten the slab end surface.

[0033] The above-mentioned protrusions 40 to 43 have different widths and heights. Specifically, the width of the protrusions increases in the order of 40 to 43. In terms of height, protrusion 41 is the tallest, and the height decreases as you move towards the later stages. With this configuration, as shown in Figure 2, in the first hole mold K1, the rolled material A has a cutout 50 made by the protrusion 40 on the slab end face. As rolling progresses from the second hole mold K2 to the fourth hole mold K4, the cutout 50 becomes shallower, and the slab end face is widened, so that the width of the slab end face of the rolled material A (also called the flange width) is progressively wider. The slab end face formed in this way corresponds to the flange portion in an H-beam. Therefore, in the following explanation, the widened slab end face will also be called the flange portion 80, and its width will be referred to as the flange width.

[0034] As described above, as the rolled material A is sequentially rolled in the first to fourth hole molds K1 to K4, the slab end face (flange portion 80) is widened. In this embodiment, the slab end face widths during the first pass in each hole mold (first to fourth hole molds) are b0, b1, b2, and b3. In the first hole mold K1, the slab end face is not widened, and only the indentation 50 is made, so the end face width b0 is the same as the thickness of the material slab. The slab end face widths in each hole mold are, in order, b0 <b1<b2<b3となる。

[0035] The rolling process using the first to fourth holes K4, as described above with reference to Figure 2, is also called the edging rolling process, which shapes the rolled material A into a predetermined approximate dogbone shape, and is carried out with the rectangular cross-section material slab standing upright. After the edging rolling process, the rolled material A is rotated by 90° or 270° and sent to the fifth hole K5, where it is rolled into an H-shaped rough material 13 with a so-called dogbone shape.

[0036] Figure 3 is a schematic diagram of the fifth hole type K5. The fifth hole type K5 consists of a pair of horizontal rolls, an upper hole type roll 85 and a lower hole type roll 86. As shown in Figure 3, in the fifth hole type K5, the rolled material A formed up to the fourth hole type K4 is rotated by 90° or 270°, and the flange portions 80 that were located at the upper and lower ends of the rolled material A up to the fourth hole type K4 are positioned to lie on the rolling pitch line. Then, in the fifth hole type K5, the web portion 82, which is the connecting portion between the two flange portions 80, is reduced.

[0037] Here, the upper and lower hole type rolls 85 and 86 of the fifth hole type K5 have a shape in which recessed portions 85a and 86a of a predetermined length L1 are formed in the center of the roll body length. With this hole type configuration shown in Figure 3, the reduction of the web portion 82 is performed partially, and after reduction, the web portion 82 will have reduced portions 82a at both ends in the web height direction and a raised portion 82b in the center as an unreduced portion. In this way, rolling is performed to form a raised portion 82b on the web portion 82 of a rolled material with a so-called dogbone shape. In this fifth hole mold K5, a rolling process is performed that partially reduces the web portion 82 to form a raised portion 82b. Therefore, this hole mold is also referred to as a "raised portion generating hole mold" or a "web partial rolling hole mold." The width length of the formed raised portion 82b is the same as the width length L1 of the recessed portions 85a and 86a (relief amount L1, described later). Here, as shown in the enlarged view of Figure 3, the width length L1 of the recessed portions 85a and 86a in this specification is defined as the width length at a depth of 1 / 2 of the depth hm of the recessed portions 85a and 86a, and the relief amount L1, described later, is defined in the same way.

[0038] The rolling process using the fifth-hole mold K5 is carried out in an approximately H-shaped position, with the rolled material A formed in the etching rolling process rotated by 90° or 270°, and is therefore also called the flat rolling process.

[0039] (Outline of the intermediate rolling process according to the present invention) In the H-shaped rough material 13 with a raised portion 82b formed on the web portion 82 in the fifth hole type K5 described above, rolling is then performed in the intermediate universal rolling mill 5 (see Figure 1). Figure 4 is a schematic diagram showing the roll configuration of the intermediate universal rolling mill 5, and a cross-section of the rolled material A is also shown in the figure. Figure 5 is a schematic diagram showing the removal of the raised portion in the intermediate universal rolling mill, where (a) shows the state in which the inner surface of the flange portion is not in contact with the outer surface of the horizontal roll, and (b) shows the state in which the inner surface of the flange portion is in contact with the outer surface of the horizontal roll. The dashed lines in the figures indicate the roll axis of each roll.

[0040] As shown in Figure 4, the intermediate universal rolling mill 5 is equipped with a pair of upper and lower horizontal rolls 105a and 105b and a pair of left and right vertical rolls 106a and 106b. In this intermediate universal rolling mill 5, for example as shown in Figure 5(b), the web portion 82 including the raised portion 82b is reduced by the horizontal rolls 105a and 105b while the outer surface of the flange portion 80 is restrained by the vertical rolls 106a and 106b (raised portion removal process). In this raised portion removal process, it is preferable that the rolling process is performed with the inner surface of the flange portion 80 in contact with the sides of the horizontal rolls 105a and 105b. The state in which the inner surface of the flange portion 80 is in contact with the sides of the horizontal rolls 105a and 105b may be in all passes when the rolling process is performed in multiple passes, or it may be in some passes. In other words, it is sufficient that the inner surface of the flange portion 80 is in contact with the sides of the horizontal rolls 105a and 105b during at least one pass of the rolling process.

[0041] In the state shown in Figure 5(a), the flange portion 80 is unrestrained when the raised portion 82b is removed, but rolling stability can be ensured because the outer surface of the flange is restrained by the vertical rolls. Also, in the state shown in Figure 5(b), the flange portion 80 is restrained when the raised portion 82b is removed by adjusting the roll opening of the vertical rolls, so that flange material imbalance and poor centering do not occur when widening the web interior, and rolling stability can be ensured.

[0042] In addition, along with this raised portion removal process, a rolling process (widening rolling process) may be performed in which horizontal rolls 105a and 105b are brought into contact with the inner surface of the flange portion 80 to widen the inner dimensions of the web portion 82. That is, in the intermediate universal rolling mill 5, a rolling process may be performed in which the raised portion 82b is removed while the inner dimensions of the web portion 82 are widened.

[0043] The rolling process in this intermediate universal rolling mill 5 promotes the expansion in the web height direction and metal flow to the flange portion 80 as the raised portion 82b is reduced, making it possible to perform the rolling process with minimal reduction in flange surface area.

[0044] Furthermore, for the rolled material A formed by rolling in the first to fifth hole molds K1 to K5 and the intermediate universal rolling mill 5 described above, further widening of the web portion 82 may be performed as needed. In this case, for example, a separate hole mold for widening may be provided in the roughing mill, or a separate universal rolling mill may be provided to perform the widening, or the widening of the web portion 82 may be performed in the edger rolling mill 9 or the finishing universal rolling mill 8 shown in Figure 1.

[0045] Using the first to fifth hole molds K1 to K5 described above, an H-shaped rough material 13 with raised portions 82b is formed. The H-shaped rough material 13 thus formed is subjected to multiple passes of reverse rolling using a rolling mill train consisting of two rolling mills, an intermediate universal rolling mill 5 and an edger rolling mill 9, to remove the raised portions 82b and form an intermediate material 14. The intermediate material 14 is then finished-rolled into the product shape in a finishing universal rolling mill 8 to produce an H-shaped steel product 16 (see Figure 1).

[0046] In this embodiment, after edging rolling, a process is performed to form a raised portion 82b in the fifth hole mold K5, and then the raised portion 82b is removed in the intermediate universal rolling mill 5, and the inner width of the web portion 82 is widened. This makes it possible to roll and shape an intermediate material 14 with a larger flange width than conventional methods, and as a result, it becomes possible to manufacture H-shaped steel products with a larger flange width than conventional methods. Furthermore, by adopting a process that removes the raised portion 82b after it has been formed, the process design is such that the hole mold related to the flat rolling process is limited to only the raised portion generation hole mold (fifth hole mold K5 in this embodiment), and the removal of the raised portion is performed in the intermediate rolling process, thereby suppressing the equipment constraint load related to the roll shell length of the rough rolling mill, etc. (rough rolling mill 4 in this embodiment).

[0047] Here, the inventors investigated the preferred conditions for generating raised portions in a rough rolling process (fifth hole mold K5) and eliminating those raised portions in an intermediate rolling process (intermediate universal rolling mill 5), as described in this embodiment, and obtained the findings described below. These findings will be explained below with reference to the drawings, etc.

[0048] (Conventional flat rolling process and widening rolling) Table 1 below shows the roll die specifications for a conventional die design using the web widening rolling method, illustrating an example of the conditions for widening the web interior using flat rolling and widening rolling without forming raised sections during flat rolling. Furthermore, Table 2 below shows the roll die specifications for a conventional die design using a web partial rolling method employing raised-area generation rolling and raised-area removal rolling. It illustrates an example of the conditions under which raised areas are formed and removed using a die engraved on a roughing mill as part of a flat rolling process.

[0049] [Table 1] [Table 2]

[0050] As shown in Table 1, when widening the web interior without forming a raised section in planar rolling, the interior must be finished to a product-equivalent level by the intermediate universal rolling stage. In this case, since no raised section is formed, the effect of promoting the expansion in the web height direction due to the reduction of the raised section 82b and the metal flow to the flange section 80, and performing rolling with minimal flange reduction, cannot be obtained, and there is a risk that sufficient flange thickness will not be secured. In other words, the flange generation efficiency cannot be improved, and it becomes difficult to manufacture products with wider flanges than conventional methods.

[0051] Furthermore, as shown in Table 2, if the internal dimensions of the raised section generation hole type and the raised section removal hole type are set to be the same, it is necessary to match them with the internal dimensions of the next process, Universal No. 1. As a result, the internal dimensions of the fourth hole type K4, which is the edging finish, are large, and the amount of edging cannot be secured, thus limiting the amount of material that can be added.

[0052] (Flat rolling process and widening rolling according to the present invention) Tables 3 and 4 below show the roll die specifications for the die design according to the present invention, and illustrate an example of the conditions when the raised portion is formed using a die engraved in the roughing mill as part of a flat rolling process, and the raised portion is removed in a subsequent intermediate universal rolling process.

[0053] [Table 3] [Table 4]

[0054] In the configuration shown in Table 3, the rough rolling mill performs both raised section formation rolling and widening rolling processes during die rolling. Subsequently, the intermediate universal rolling mill performs raised section reduction (raised section removal process). As a result, the outer dimensions of the fourth die K4 with edging can be designed in the same way as the conventional rolling method shown in Table 1, allowing for a larger edging amount and increased flange thickness. Furthermore, the reduction of the raised section 82b promotes expansion in the web height direction and metal flow to the flange section 80, enabling rolling and molding with minimal flange reduction. In other words, the flange formation efficiency is improved. Furthermore, comparing the hole configurations in Tables 1 and 3, the number of holes engraved in the roughing mill (2Hi) is the same, and the arrangement is also similar. This allows for the maintenance of rolling stability by performing web widening rolling while avoiding equipment constraints such as insufficient roll shell length, and improves flange generation efficiency through the creation and elimination of the raised portion 82b.

[0055] In the configuration shown in Table 4, the roughing mill performs raised section formation rolling and widening rolling during die rolling, and the subsequent intermediate universal rolling mill performs both raised section reduction (raised section removal process) and widening rolling processes. This promotes the expansion in the web height direction and metal flow to the flange section 80 as the raised section 82b is reduced, allowing the rolling process to be carried out with minimal flange reduction, thereby improving flange formation efficiency while avoiding equipment constraints such as insufficient roll shell length. In addition, because widening rolling is performed in the intermediate universal rolling mill, the amount of web internal width widening during widening rolling in the roughing mill can be kept small, thereby suppressing flange pulldown.

[0056] Here, the rolling condition that impairs rolling stability when removing raised sections in an intermediate universal rolling mill is the occurrence of flange thickness imbalance during the removal of raised sections 82b. To avoid this, it is considered necessary that the inner surface of the flange section 80 and the outer surface of the horizontal roll remain in contact for at least one pass during the removal of raised sections. When the inner surface of the flange section 80 and the outer surface of the horizontal roll make contact during the raised section removal rolling process, the left-right deformation of the flange section 80 is equalized, thereby maintaining rolling stability. At this time, it is desirable to keep the inner surface of the flange section 80 and the outer surface of the horizontal roll in contact, and to keep the roll opening (distance between the left and right vertical rolls) of the intermediate universal rolling mill constant at a predetermined opening until the removal of raised sections is complete.

[0057] As described above, in the processes with the hole configurations shown in Tables 3 and 4, the raised portion is reduced (removed) in the intermediate universal rolling mill. When employing a process in which the raised portion 82b is formed and then removed, the removal of the raised portion 82b is performed in the intermediate universal rolling mill, thus constraining of the rolled material A by the left and right vertical rolls is achieved. Therefore, dimensional deterioration does not occur when the web height expands due to the removal of the raised portion, and rolling stability is maintained. In addition, since the roll gap of the vertical rolls can be freely changed in the intermediate universal rolling mill, rolling of the flange inner surface, which is prone to scratches, can be performed under conditions in which the flange inner surface easily makes contact, thereby improving rolling stability and reducing dimensional variations.

[0058] (An example of a path schedule according to the present invention) Tables 5 and 6 below show an example of a specific pass schedule for the raised section removal process according to the present invention. Figure 7 is an explanatory diagram of the numerical values ​​in Tables 5 and 6, where (a) is the dimensions of the rolled material and (b) is the universal rolling roll gap. The dashed lines in the figure indicate the roll axis of each roll. Here, as shown in Figure 7(a), the dimensions of the rolled material at the end of the flat rolling stage were a web thickness of 100 mm, a raised section thickness of 200 mm (50 mm on one side), a web height of 1300 mm, and a web inner width of 900 mm. Also, as shown in Figure 7(b), the H gap shown in Tables 6 and 7 below is the upper and lower horizontal roll gap (horizontal roll gap), and the V gap is the roll gap between the horizontal roll and the vertical roll (vertical roll gap).

[0059] [Table 5] [Table 6]

[0060] The two pass schedules shown in Tables 5 and 6 both have the same total number of passes (7), and the H-gap compression patterns are identical. The pass schedule in Table 5 is an example of fabricating a larger H-beam product by utilizing the reduction of the raised portion 82b to widen the web interior. As the raised portion 82b is reduced, the web height is increased with each pass. In the pass schedule in Table 5, the raised portion 82b is reduced to narrow the H gap, and the V gap is widened as the web height increases. In this pass schedule, the amount of web interior widening due to pressing the inner surface of the flange by the horizontal roll in the same pass is greater than the amount of web interior widening due to the reduction of the raised portion 82b. In addition, in this pass schedule, the web interior widening is performed while the widening of the web height is constrained by the vertical roll. As a result, when the raised portion 82b is removed (during the 7th pass), the web height becomes 1360 mm.

[0061] Furthermore, the pass schedule in Table 6 is an example of reducing the raised portion 82b without increasing the web height with each pass. Specifically, the V-gap is kept constant from the third pass onward, and only the raised portion 82b is reduced, resulting in a final web height of 1260 mm. Referring to Tables 5 and 6, the pre-rolling materials used are of the same dimensions (see Figure 7(a)). In other words, by adjusting the pass schedule when removing raised sections in the intermediate universal rolling mill, it is possible to roll materials of the same dimensions into rolled materials with different dimensions and shapes, thereby producing different dimensions for the final H-beam products.

[0062] (Ratio of relief amount (width of raised area formation) in the web method) As described above, in the fifth hole type K5 according to this embodiment (see Figure 3), a raised portion 82b is formed in the center of the web portion 82 of the rolled material A, and the formed raised portion 82b is removed in the subsequent rolling process. Then, widening rolling of the web is performed as needed during or after the removal of the raised portion to form an intermediate material. However, in order to manufacture large H-shaped steel products with a larger flange width than conventional methods, it is desirable to make the flange width of the H-shaped rough material as large as possible. The inventors have found that changing the width and length L1 of the raised portion 82b formed in the fifth hole type K5, which is a raised portion generation hole type (i.e., the amount of relief in the web method during rolling in the fifth hole type K5), results in a difference in the final flange width. This is because, while increasing the width and length of the raised portion 82b makes it easier to secure flange material, the flange width decreases due to the longitudinal stretching action of the rolled material A during the subsequent removal of the raised portion.

[0063] Therefore, in order to determine a suitable range for the web relief amount (hereinafter also simply referred to as "relief amount L1") in the rolling process using the fifth hole mold K5, the inventors focused on the relationship between the relief rate and the increase or decrease in flange width after the H-shaped rough material was formed, and derived a suitable numerical range for the relief rate. The relief rate is a value defined by the following formula (1). Escape rate [%] = (Escape amount L1 / Web area L2) × 100 ... (1)

[0064] Figure 6 is a graph showing the relationship between the relief ratio and the increase / decrease rate of flange width after fabrication of the H-shaped rough material. In Figure 6, the flange width increase / decrease rate is the value showing the flange width for each relief ratio (12% to 55%), with the flange width when the relief ratio is 0% being set as the base value (1.000).

[0065] As shown in Figure 6, the flange width of the H-shaped rough material tends to increase as the relief ratio increases, but in the region where the relief ratio is approximately 25% or more, the increase or decrease in flange width remains almost constant (see the dashed line in the graph). As shown in Figure 6, when manufacturing large H-shaped steel products with wider flanges than conventional products, it is desirable to use a rolling process that increases the flange width of the H-shaped rough material. Therefore, it is desirable to set the relief ratio within a range of 25% to 50%.

[0066] Although an example of an embodiment of the present invention has been described above, the present invention is not limited to the illustrated form. It will be clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the idea described in the claims, and these will naturally also fall within the technical scope of the present invention.

[0067] For example, in the above embodiment, a technique was described in which the rolled material A is formed using four dies, the first to fourth dies K1 to K4, and then the intermediate material is rolled using the fifth die K5 and an intermediate universal rolling mill. However, the number of dies used for the rough rolling process is not limited to this, and the rolling process shown in the first to fourth dies K4 may be carried out using even more dies. In other words, the dies configuration shown in the above embodiment is just one example, and the number of dies engraved in the rough rolling mill 4 can be changed arbitrarily and appropriately to the extent that the rough rolling process can be carried out suitably.

[0068] Furthermore, in the above embodiment, the first to fourth hole molds K1 to K4 describe a method for forming H-shaped rough materials (so-called dogbone materials) as represented in Patent Document 1. However, the rolling molding technology in the fifth hole mold K5 and the intermediate universal rolling mill according to the present invention is not only applicable to rolled material A formed by such technology, but can also be applied to molding methods in which incisions are made in the upper and lower ends (slab end faces) of rolled material A, and the parts separated to the left and right by these incisions are bent to the left and right to form flange portions 80.

[0069] (Other embodiments of the present invention) Furthermore, although the above embodiment describes a configuration in which raised section generation rolling and widening rolling are performed by hole-type rolling in a roughing mill (BD), the scope of application of the present invention is not limited to this. For example, it is also possible to set up two rolling mills (two stands) that perform intermediate universal rolling, and in these two rolling mills, raised section generation rolling is performed in the first mill, and then raised section removal rolling is performed in the second mill. In other words, it is also possible to perform both raised section generation and raised section removal entirely by universal rolling. Note that these two rolling mills may be arranged in tandem.

[0070] In this case, the horizontal rolls of the universal rolling mill that perform the raised portion generation rolling will have recesses formed in a shape corresponding to the shape of the fifth hole type (raised portion generation hole type) described in the above embodiment.

[0071] Table 7 below shows the specifications of a roll hole type according to another embodiment of the present invention, and illustrates an example of the conditions when the formation and removal of the raised portion is performed using two intermediate universal rolling mills.

[0072] [Table 7]

[0073] In the configuration shown in Table 7, the formation and reduction (removal) of the raised portion are performed in two intermediate universal rolling mills. This promotes the expansion in the web height direction and metal flow to the flange portion 80 as the raised portion 82b is reduced, and rolling can be performed with minimal flange reduction. In other words, the flange formation efficiency is improved. In addition, since the material to be rolled A is restrained by the left and right vertical rolls, dimensional deterioration does not occur when the web height expands as the raised portion is removed, and rolling stability is maintained. [Industrial applicability]

[0074] This invention can be applied to a manufacturing method for producing H-shaped steel using, for example, a slab with a rectangular cross-section as the material. [Explanation of Symbols]

[0075] 1…Rolling equipment 3...Heating furnace 4...Roughing mill 5…Intermediate Universal Rolling Mill 8…Finishing Universal Rolling Mill 9… Edger rolling mill 11…Slab 13...H-shaped rough profile 14…Intermediate material 16...H-shaped steel products 30… cabinet 33…Top-hole type roll 34…Pre-drilled roll 40, 41, 42, 43...Protrusion 50...Interruption 80...Flange section 82...Web Department 82a...Reduction part 82b...Protuberant part (unpressed part) 85... Upper-hole type roll (5th hole type) 85a... recessed area 86... Pre-drilled roll (5th hole type) 86a... recessed area 105a, 105b…(a pair of upper and lower) horizontal rolls 106a, 106b… (a pair of left and right) vertical rolls K1…First Hole Type K2…Second Hole Type K3…Third Hole Type K4…4th hole type K5… Fifth type of hole (hole type generated in the raised part) L…manufactured by Rakuno A…pressure-extended material

Claims

1. A method for manufacturing H-shaped steel, comprising a rough rolling process, an intermediate rolling process, and a finish rolling process, In the rough rolling process, An edging rolling process in which the rolled material is rolled into a predetermined approximate dogbone shape, A flat rolling process is performed in which the rolled material, after the edging rolling process is completed, is rotated 90° or 270° to form a raised portion in the center of the web. In the aforementioned intermediate rolling process, The raised portion removal process, in which the raised portion is reduced and removed, is performed in the intermediate universal rolling mill. In either or both of the above flat rolling process and the raised portion removal process, widening rolling is performed to widen the inner width of the web portion of the rolled material. In the aforementioned flat rolling process, the raised portion is not reduced or removed. A method for manufacturing an H-shaped steel, characterized in that, in the raised portion removal step, the vertical roll gap of the intermediate universal rolling mill is enlarged in accordance with the web height expansion due to the reduction of the raised portion, and rolling is performed.

2. A method for manufacturing H-shaped steel, comprising a rough rolling process, an intermediate rolling process, and a finish rolling process, In the rough rolling process, An edging rolling process in which the rolled material is rolled into a predetermined approximate dogbone shape, A flat rolling process is performed in which the rolled material, after the edging rolling process is completed, is rotated 90° or 270° to form a raised portion in the center of the web. In the aforementioned intermediate rolling process, The raised portion removal process, in which the raised portion is reduced and removed, is performed in the intermediate universal rolling mill. In either or both of the above flat rolling process and the raised portion removal process, widening rolling is performed to widen the inner width of the web portion of the rolled material. In the aforementioned flat rolling process, the raised portion is not reduced or removed. A method for manufacturing H-shaped steel, characterized in that, in the step of eliminating the raised portion, the rolling process is carried out while keeping the vertical roll gap of the intermediate universal rolling mill constant.

3. The rolling process in the aforementioned raised portion removal step is performed in multiple passes. A method for manufacturing an H-shaped steel beam according to claim 1 or 2, characterized in that, in at least one of the multiple passes, the rolling process is carried out with the inner surface of the flange of the material to be rolled in contact with the horizontal roll.

4. The method for manufacturing an H-shaped steel beam according to claim 2, characterized in that, in the step of removing the raised portion, the roll opening of the vertical rolls of the intermediate universal rolling mill remains constant until the removal of the raised portion is completed.

5. The aforementioned flat rolling process A method for manufacturing an H-shaped steel beam according to any one of claims 1 to 4, characterized in that the width of the raised portion formed therein is set to 25% or more and 50% or less of the internal width of the web portion of the rolled material.

Images