JP6627641B2 - Method for manufacturing H-section steel - Google Patents

Description

  The present invention relates to a manufacturing method for manufacturing an H-section steel from a slab or the like having a rectangular cross section, for example.

  In the case of manufacturing an H-section steel, materials such as slabs and blooms extracted from a heating furnace are formed into a rough material (a so-called dog-bone-shaped material to be rolled) by a rough rolling machine, and the above-mentioned material is formed by an intermediate universal rolling machine. The thickness of the web or flange of the crude material is reduced, and at the same time, the flange of the material to be rolled is subjected to width reduction and forging and shaping of the end face by an edger rolling mill close to the intermediate universal rolling mill. Then, an H-section steel product is formed by the finishing universal rolling mill.

  In such a method of manufacturing an H-section steel, when forming a so-called dogbone-shaped rough material from a slab material having a rectangular cross section, an interruption is made in the slab end face in the first die in the rough rolling process. Later, a technique is known in which the interruption is expanded in the second and subsequent dies, or the edging rolling is performed by increasing the interruption depth, and the interruption of the slab end face is eliminated in the subsequent dies. Patent Document 1).

JP-A-7-88501

  In recent years, with the enlargement of structures and the like, the manufacture of large H-shaped steel products has been desired. In particular, there is a demand for a product in which a flange that greatly contributes to the strength and rigidity of the H-section steel is made wider than before. In order to manufacture an H-shaped steel product having a wide flange, it is necessary to form a material to be rolled having a larger flange width than in the past from the shaping in the rough rolling process.

  However, for example, in the technique disclosed in the above-mentioned Patent Document 1, in a method of interrupting an end face (a slab end face) of a material such as a slab, edging the end face, and performing rough rolling using the width expansion, There is a limit to widening the flange. In other words, in order to increase the width of the flange in the conventional rough rolling method, the width is improved by techniques such as wedge design (design of an interruption angle), rolling reduction, and lubrication adjustment. Since it does not contribute significantly, the width expansion ratio, which indicates the ratio of the amount of expansion of the flange width to the amount of edging, is about 0.8 even under the condition where the efficiency of the initial stage of edging is the highest, and edging is performed with the same hole type. Under repeated conditions, it is known that the value decreases as the amount of expansion of the flange width increases, and finally reaches about 0.5. It is also conceivable to increase the edging amount by increasing the size of the raw material such as slabs, but it is not possible to achieve a sufficient width of the product flange because the equipment scale and rolling reduction of the rough rolling mill are limited. There are circumstances.

  Further, when manufacturing a large H-shaped steel product, rolling shaping is performed in a plurality of passes in order to perform shaping of a flange, a web, and the like, but it is desirable that the number of passes is small. This is because the slab width must be increased in order to manufacture a large H-shaped steel product, in particular, to increase the width of the flange. However, when the slab width is increased, the edging amount in edging rolling increases. This is because there is a concern that the number of passes increases because the amount of reduction per pass is limited. In addition, when the slab width is increased, the slab width / slab thickness ratio in the material is increased, and buckling is liable to occur during edging rolling. Since the bending is suppressed, the number of passes may increase.

  In view of such circumstances, an object of the present invention is to provide a rough rolling process using a die in the manufacture of an H-section steel, in which a sharp end-shaped projection on the end face of a material such as a slab interrupts the interruption. In addition to suppressing the occurrence of shape defects in the material to be rolled by sequentially bending the formed flange portion, the material width in the process is made smaller than before, and the shape of the protrusion is made suitable. Accordingly, it is an object of the present invention to provide an H-beam manufacturing technique capable of realizing a reduction in the number of passes at the time of rolling molding as compared with the related art and efficiently and stably manufacturing an H-beam product having a large flange width. .

  In order to achieve the above object, according to the present invention, there is provided a method for producing an H-beam including a rough rolling step, an intermediate rolling step, and a finish rolling step, wherein the rough rolling step is performed on a rectangular cross-sectional material. The machine is engraved with a plurality of four or more molds for shaping the material to be rolled. In the plurality of molds, one or more passes of the material to be rolled are formed. In the mold and the second mold, a projection is formed to insert an interruption vertically in the width direction of the material to be rolled. In the molding in the second mold, the depth of the interruption formed in the first mold is formed. In the third and subsequent molds of the plurality of molds, a step of sequentially bending the divided portions formed by the interruption is performed, and the protrusions formed on the second molds are formed. The tip angle is 25 ° or more and 40 ° or less, and the tip of the projection An end section radius is designed to be 30 mm or less, and a method for producing an H-section steel is provided.

  When the radius of curvature of the tip of the protrusion formed in the second mold is designed to be 20 mm or less, the rolling reduction per rolling molding pass in the second mold may be set to a maximum of 180 mm.

  When the radius of curvature of the tip of the protrusion formed in the second mold is designed to be 30 mm or less, the rolling reduction per rolling shaping pass in the second mold may be set to 90 mm at the maximum.

  According to the present invention, in a rough rolling process using a groove when manufacturing an H-section steel, a sharp interruption is formed deeply on an end face of a material such as a slab by a projection having an acute-angled tip shape, and thus formed. By successively bending the flanges, it is possible to suppress the occurrence of shape defects in the material to be rolled, and in the process, make the material width smaller than before and make the shape of the projections more suitable, so that the rolling molding can be made as compared to the conventional one By reducing the number of passes at the time, an H-shaped steel product having a large flange width can be efficiently and stably manufactured.

It is an outline explanatory view about a production line of H section steel. It is a schematic explanatory drawing of a 1st hole type. It is a schematic explanatory drawing of a 2nd hole type. It is a schematic explanatory drawing of a 3rd hole type. It is a schematic explanatory drawing of a 4th hole type. It is a schematic explanatory drawing of a 5th hole type (flat molding hole type). It is a schematic explanatory drawing which shows the state of the to-be-rolled material in the intermediate | middle pass of the rolling shaping in a 2nd die. It is a graph which shows the relationship between wedge tip curvature radius R and rolling load t in the 2nd die. It is a graph which shows the relationship between the amount of edging per pass and the amount of buckling of the material to be rolled in the second die. It is explanatory drawing regarding the amount of buckling.

  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 function and configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an explanatory diagram of an H-section steel production line T including a rolling facility 1 according to the present embodiment. As shown in FIG. 1, a heating furnace 2, a sizing mill 3, a rough rolling mill 4, an intermediate universal rolling mill 5, and a finishing universal rolling mill 8 are arranged in the manufacturing line T in order from the upstream side. An edger rolling mill 9 is provided near the intermediate universal rolling mill 5. In the following, for the sake of explanation, the steel materials on the production line T are collectively referred to as “rolled material A”, and the shape of the steel material may be appropriately illustrated using broken lines, diagonal lines, or the like in each drawing.

  As shown in FIG. 1, in a production line T, a material having a rectangular cross section (a material to be rolled A), for example, a slab 11 extracted from a heating furnace 2 is roughly rolled in a sizing mill 3 and a rough rolling mill 4. Next, intermediate rolling is performed in the intermediate universal rolling mill 5. At the time of the intermediate rolling, the edge of the flange (the flange corresponding portion 12) of the material to be rolled is reduced by the edger rolling machine 9 if necessary. In the normal case, the rolls of the sizing mill 3 and the roughing mill 4 are engraved with a so-called flat molding die for reducing the thickness of the edging die and the web portion and forming the shape of the flange portion. Then, an H-shaped rough shaped material 13 is formed by reverse rolling in a plurality of passes, and the H-shaped rough shaped material 13 is formed by using a rolling mill row including two rolling mills of the intermediate universal rolling mill 5 and the edger rolling mill 9. , A plurality of passes are applied, and the intermediate member 14 is formed. Then, the intermediate material 14 is finish-rolled into a product shape in the finishing universal rolling mill 8 to produce an H-shaped steel product 16.

  Here, the slab thickness T of the slab 11 extracted from the heating furnace 2 is, for example, in the range of 240 mm or more and 310 mm or less. This is a slab dimension used when manufacturing a general H-shaped steel product.

  Next, a description will be given of a groove configuration and a groove shape engraved in the sizing mill 3 and the rough rolling mill 4 shown in FIG. 1 with reference to the drawings. FIGS. 2 to 6 are schematic explanatory diagrams of the sizing mill 3 for performing the rough rolling process and the dies formed in the rough rolling mill 4. Here, the first to fourth molds to be described may be, for example, all engraved on the sizing mill 3, and the sizing mill 3 and the roughing mill 4 are provided with five first to fifth molds. The hole shape may be separately engraved. That is, the first die to the fifth die may be engraved on both the sizing mill 3 and the rough rolling mill 4 or may be engraved on one of the rolling mills. In the rough rolling process in the production of a normal H-section steel, modeling in one or a plurality of passes is performed in each of these molds.

  Further, in the present embodiment, a case where five holes are engraved will be described as an example, but the number of holes is not necessarily five holes, and the number of holes is not less than five. It may be. That is, any hole-shaped structure suitable for forming the H-shaped rough material 13 may be used. In addition, in FIGS. 2 to 6, the outline final path shape of the material A to be rolled at the time of molding in each die is indicated by a broken line.

  FIG. 2 is a schematic explanatory view of the first die K1. The first die K1 is engraved on a pair of horizontal rolls, an upper die roll 20 and a lower die roll 21. In the gap between the upper die roll 20 and the lower die roll 21, the material A to be rolled is formed. Pressed and shaped. Further, on the peripheral surface of the upper hole type roll 20 (that is, on the upper surface of the first hole type K1), a projection 25 protruding toward the inside of the hole type roll is formed. Further, a projection 26 protruding toward the inside of the mold is formed on the peripheral surface of the pilot mold roll 21 (that is, the bottom surface of the first mold K1). The projections 25 and 26 have a tapered shape, and the dimensions such as the projection length are the same for the projection 25 and the projection 26. The height (projection length) of the projections 25 and 26 is h1, and the tip angle is θ1a.

  In the first die K1, the projections 25 and 26 are pressed against the upper and lower ends (slab end faces) of the material A to be rolled, and interruptions 28 and 29 are formed. Here, it is desirable that the tip angle (also referred to as a wedge angle) θ1a of the protrusions 25 and 26 is, for example, 25 ° or more and 40 ° or less.

  Here, it is preferable that the die width of the first die K1 is substantially equal to the thickness of the rolled material A (that is, the slab thickness). Specifically, by making the width of the groove at the tip end of the projections 25 and 26 formed in the first groove K1 and the slab thickness the same, the right and left centering property of the material A to be rolled is appropriately secured. Is done. Further, by adopting such a configuration of the groove shape, as shown in FIG. 2, at the time of shaping with the first groove shape K1, the upper and lower ends (slab end faces) of the material A to be rolled have the protrusions. The portions 25 and 26 and a part of the side surfaces (side walls) of the die are in contact with the material A to be rolled, and the first hole is formed in the upper and lower ends of the slab divided into four elements (parts) by the interrupts 28 and 29. It is preferable that active reduction is not performed on the upper and lower surfaces of the mold K1. This is because the reduction by the upper surface and the lower surface of the groove shape causes the material A to be rolled to elongate in the longitudinal direction, and lowers the efficiency of forming a flange (a flange portion 80 described later). That is, in the first die K1, the projections 25 and 26 are pressed against the upper and lower ends (slab end faces) of the material A to be rolled, and the projections 25 and 26 when the interruptions 28 and 29 are formed are reduced. The amount (the amount of reduction of the wedge tip) is sufficiently larger than the amount of reduction at the upper and lower ends of the slab (the amount of reduction of the slab end surface), thereby forming interruptions 28 and 29.

  FIG. 3 is a schematic explanatory view of the second hole type K2. The second die K2 is engraved on an upper die roll 30 and a lower die roll 31, which are a pair of horizontal rolls. On the peripheral surface of the upper hole type roll 30 (that is, the upper surface of the second hole type K2), a projection 35 projecting toward the inside of the hole type is formed. Further, a projection 36 projecting toward the inside of the mold is formed on the peripheral surface of the pilot mold roll 31 (that is, the bottom surface of the second mold K2). The projections 35 and 36 have a tapered shape, and the dimensions of the projections 35 and 36 are equal to each other. It is desirable that the tip angles of these projections 35 and 36 be wedge angles θ1b of 25 ° or more and 40 ° or less.

  The wedge angle θ1a of the first die K2 is set to be equal to the wedge angle of the second die K2 at the subsequent stage in order to secure the thickness of the front end of the flange-equivalent portion, increase the inductivity, and ensure the stability of rolling. It is preferable that the angle is the same as θ1b.

  The height (projection length) h2 of the projections 35 and 36 is higher than the height h1 of the projections 25 and 26 of the first hole type K1, and h2> h1. In addition, it is preferable in terms of rolling dimensional accuracy that the tip angles of the projections 35 and 36 are the same as the tip angles of the projections 25 and 26 of the first die K1. In the gap between the upper hole type roll 30 and the lower hole type roll 31, the material A to be rolled after passing the first hole type K1 is further formed.

Here, the height h2 of the projections 35 and 36 formed on the second die K2 is higher than the height h1 of the projections 25 and 26 formed on the first die K1. Similarly, the penetration length into the upper and lower ends (slab end faces) of the second hole type K2 is longer. The penetration depth of the projections 35 and 36 into the material A to be rolled in the second die K2 is the same as the height h2 of the projections 35 and 36. That is, the penetration depth h1 'of the projections 25 and 26 into the material A to be rolled in the first die K1 and the depth of penetration of the projections 35 and 36 into the material A to be rolled by the second die K2. h2 has a relationship of h1 ′ <h2.
The angle θf formed between the upper surfaces 30a, 30b and the lower surfaces 31a, 31b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the projections 35, 36 is shown in FIG. Each of the four points shown is formed at about 90 ° (substantially right angle).

  As shown in FIG. 3, since the intrusion length of the protrusion when pressed against the upper and lower ends (slab end faces) of the material A to be rolled is long, in the second mold K2, the first mold K1 is used. The shaping is performed so that the interruptions 28 and 29 formed in are deeper, and interruptions 38 and 39 are formed. The width of the flange piece at the end of the flange forming step in the rough rolling step is determined based on the dimensions of the interruptions 38 and 39 formed here.

Further, the molding with the second hole die K2 shown in FIG. 3 is performed by multiple passes. In this multi-pass molding, holes are formed at the upper and lower ends (slab end faces) of the material A to be rolled except for the projections 35 and 36. The mold and the material to be rolled A are not in contact with each other, and the rolling material A is not actively reduced in these passes. This is because the rolling reduction causes the material A to be rolled to elongate in the longitudinal direction, thereby lowering the efficiency of forming a flange equivalent portion (corresponding to a flange portion 80 described later).
However, it is not indispensable that the contact is made in all the passes. For example, only in the final pass, the upper and lower ends (slab end faces) of the material A to be rolled contact the inside of the die, and the slab end face reduction amount ΔE is a positive value. (ΔE> 0). This is because if the upper end of the material A to be rolled and the inside of the die are not in contact with each other in all passes of the second die K2, a flange equivalent part (a flange part 80 to be described later) is formed asymmetrically. This is because there is a possibility that such a shape defect may occur, and there is a problem in terms of material permeability.

  FIG. 4 is a schematic explanatory view of the third hole type K3. The third hole type K3 is engraved on an upper hole type roll 40 and a lower hole type roll 41 which are a pair of horizontal rolls. On the peripheral surface of the upper hole type roll 40 (that is, the upper surface of the third hole type K3), a projection 45 projecting toward the inside of the hole type is formed. Further, on the peripheral surface of the pilot hole type roll 41 (that is, the bottom surface of the third hole type K3), a projection 46 projecting toward the inside of the hole type is formed. The projections 45 and 46 have a tapered shape, and the dimensions such as the length of the projection are the same for the projection 45 and the projection 46.

The tip angle θ2 of the protrusions 45 and 46 is wider than the angle θ1b, and the depth h3 of the protrusions 45 and 46 into the material A to be rolled is the depth of penetration of the protrusions 35 and 36. Is shorter than h2 (that is, h3 <h2). The angle θ2 is preferably, for example, 70 ° or more and 110 ° or less.
The angle θf formed between the upper surfaces 40a, 40b and the lower surfaces 41a, 41b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the projections 45, 46 is shown in FIG. Each of the four points shown is formed at about 90 ° (substantially right angle).

  As shown in FIG. 4, in the third die K3, the material A to be rolled after passing through the second die K2 is formed at the upper and lower ends (slab end faces) of the material A to be rolled in the second die K2. The interrupts 38 and 39 are interrupted 48 and 49 when the protrusions 45 and 46 are pressed. That is, in the final pass in the molding with the third hole die K3, the deepest part angle of the interruptions 48 and 49 (hereinafter also referred to as interruption angle) becomes θ2. In other words, in the second hollow mold K2, the shaping is performed such that the divided portion (the portion corresponding to the flange portion 80 described later) formed along with the formation of the interrupts 38 and 39 is bent outward.

In addition, the molding with the third die K3 shown in FIG. 4 is performed by at least one pass, and at least one pass of the at least one pass includes the upper and lower ends (slab end surfaces) of the material A to be rolled and the inside of the die (the first die). The top and bottom surfaces of the three-hole type K3 need to be in contact. However, it is not desirable that all the passes are in contact with each other. For example, only the final pass makes contact between the upper and lower ends (slab end faces) of the material A to be rolled and the inside of the die, and the slab end face reduction amount ΔE is a positive value. (ΔE> 0). This is because if the upper end of the material A to be rolled and the inside of the die are not in contact with each other in all the passes of the third die K3, the flange equivalent portion (a flange portion 80 described later) is formed asymmetrically. This is because there is a possibility that such a shape defect may occur, and there is a problem in terms of material permeability.
On the other hand, in the other passes, except for the protrusions 45 and 46, the hole shape and the material to be rolled A are not in contact with each other at the upper and lower ends (slab end surfaces) of the material A to be rolled. The material A is not actively reduced. This is because the rolling reduction causes the material A to be rolled to elongate in the longitudinal direction, thereby lowering the efficiency of forming a flange equivalent portion (corresponding to a flange portion 80 described later).

  FIG. 5 is a schematic explanatory view of the fourth hole type K4. The fourth hole type K4 is engraved on an upper hole type roll 50 and a lower hole type roll 51 which are a pair of horizontal rolls. On the peripheral surface of the upper hole type roll 50 (that is, the upper surface of the fourth hole type K4), a projection 55 projecting toward the inside of the hole type is formed. Further, on the peripheral surface of the pilot hole type roll 51 (that is, the bottom surface of the fourth hole type K4), a projecting portion 56 projecting toward the inside of the hole type is formed. The projections 55 and 56 have a tapered shape, and the dimensions such as the projection length are the same for the projection 55 and the projection 56.

The tip angle θ3 of the protrusions 55 and 56 is wider than the angle θ2, and the depth h4 of the protrusions 55 and 56 into the material A to be rolled is equal to the depth of penetration of the protrusions 45 and 46. Is shorter than h3 (that is, h4 <h3).
The angle θf formed between the upper surfaces 50a, 50b and the lower surfaces 51a, 51b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the projections 55, 56 is the third angle. Similar to the hole type K3, all of the four points shown in FIG. 5 are configured at about 90 ° (substantially right angle).

  In the fourth hole type K4, the interruptions 48 and 49 formed in the third hole type K3 at the upper and lower ends (slab end surfaces) of the material A after the third hole type K3 pass through the material A to be rolled. , And the projections 55 and 56 are pressed and spread, so that interruptions 58 and 59 are obtained. That is, in the final pass in the molding with the fourth hole die K4, the deepest part angle of the interruptions 58 and 59 (hereinafter also referred to as interruption angle) becomes θ3. In other words, in the third hole mold K3, the shaping is performed such that the divided portion (the portion corresponding to the flange portion 80 described later) formed along with the formation of the interrupts 48 and 49 is further bent outward. The upper and lower end portions of the material A to be rolled thus formed are portions corresponding to a flange of a later H-shaped steel product, and are referred to as a flange portion 80 here.

In addition, the molding with the fourth hole die K4 shown in FIG. 5 is performed by at least one pass, and at least one pass of the multi-pass molding is performed by forming the upper and lower ends (slab end faces) of the material A to be rolled with the holes. The inside of the mold (the top and bottom surfaces of the fourth hole mold K4) needs to be in contact. However, it is not desirable that all the passes are in contact with each other. For example, only the final pass makes contact between the upper and lower ends (slab end faces) of the material A to be rolled and the inside of the die, and the slab end face reduction amount ΔE is a positive value. (ΔE> 0). This is because if the upper end of the material A to be rolled and the inside of the die are not in contact with each other in all the passes of the fourth die K4, the flange equivalent portion (a flange portion 80 described later) is formed asymmetrically. This is because there is a possibility that such a shape defect may occur, and there is a problem in terms of material permeability.
On the other hand, in the other passes, except for the protrusions 55 and 56, the hole shape and the material to be rolled A are not in contact with each other at the upper and lower ends (slab end faces) of the material A to be rolled. The material A is not actively reduced. This is because the rolling reduction causes the material A to be rolled to elongate in the longitudinal direction, thereby lowering the generation efficiency of the flange portion 80.

  FIG. 6 is a schematic explanatory view of the fifth hole type K5. The fifth hole type K5 includes a pair of horizontal rolls, an upper hole type roll 85 and a lower hole type roll 86. As shown in FIG. 6, in the fifth die K5, the material A to be rolled formed up to the fourth die K4 is rotated 90 ° or 270 °, and the material A to be rolled up to the fourth die K4. The arrangement is such that the flange portions 80 located at the upper and lower ends come on the rolling pitch line. In the fifth hole type K5, the dimension of the flange width is adjusted by rolling down the web portion 82, which is a connecting portion connecting the two flange portions 80, and rolling down the flange tip portion of the flange portion 80. Thus, a so-called dogbone-shaped H-shaped rough material (H-shaped rough material 13 shown in FIG. 1) is formed. In addition, since this 5th hole type | mold K5 reduces the thickness of the web part 82 by pressing down, it is also called a web thickness reduction type | mold or a flat-shaped hole type.

  Reverse rolling of a plurality of passes is performed on the H-shaped rough material 13 formed in this manner by using a rolling mill row including two rolling mills, an intermediate universal rolling mill 5 and an edger rolling mill 9, which are known rolling mills. Is added, and the intermediate material 14 is formed. Then, the intermediate material 14 is finish-rolled into a product shape in the finish universal rolling mill 8, and an H-shaped steel product 16 is manufactured (see FIG. 1).

  As described above, the upper and lower ends (slab end faces) of the material A to be rolled are interrupted by using the first to fourth hole types K1 to K4 according to the present embodiment, and each of the left and right portions is divided by the interrupt. By shaping the portion to the left and right to form the flange portion 80, the shaping of the H-shaped rough material 13 can be performed without substantially vertically pressing down the upper and lower end surfaces of the material A (slab) to be rolled. It can be carried out. That is, it is possible to form the H-shaped rough material 13 by widening the flange width as compared with the conventional rough rolling method in which the end face of the slab is constantly reduced, and as a result, the final product having a large flange width ( H-section steel).

  Here, in the shaping method using the first to fourth shaping molds K1 to K4 described above, in particular, in the rolling shaping in the first and second shaping molds K1 and K2, in principle, the upper and lower sides of the material A to be rolled are At the end (end surface of the slab), the mold is not brought into contact with the material to be rolled A as much as possible, and no positive rolling is performed. This is to prevent the material A to be rolled from elongating in the longitudinal direction due to the reduction and to prevent the generation efficiency of the flange equivalent portion (that is, the later flange portion 80) from decreasing.

  That is, the rolling shaping in the first die K1 and the second die K2 is performed by the contact between the material A to be rolled and the projections 25 and 26 (or the projections 35 and 36) formed in the die. . FIG. 7 is a schematic explanatory view showing the state of the material A to be rolled in the intermediate pass of the rolling shaping in the second die K2, and illustrates the upper half of the material A to be rolled. In the rolling shaping in the second die K2, only the protrusions 35 and 36 as shown in FIG. 7 are in contact with the material A to be rolled in the middle of the pass, and the flange equivalent portion is subjected to shear deformation by shear deformation. The rolling load (rolling load) is extremely small because of the purpose of dividing. Therefore, the amount of reduction per pass can be increased without greatly increasing the rolling load. In addition, the amount of reduction (the amount of edging) per pass can be appropriately changed by making the tip shape (the radius of curvature R of the wedge tip) of the projections 25 and 26 (or the projections 35 and 36) suitable. It is.

  The present inventors, as described above, in the first die K1 and the second die K2, except for the projections, since the material to be rolled A and the die are rolled as much as possible without contact, It is thought that it is possible to reduce the rolling load and make the rolling reduction per one pass large as compared with the conventional method and to perform the large rolling reduction. As a result, the number of passes can be significantly increased as compared with the conventional method without causing shape defects. It has been found that reduction can be achieved.

  In view of such knowledge, the present inventors have focused on edging rolling on the material A to be rolled, which is performed in the above-described grooved configuration, and particularly focused on rolling shaping with the first grooved die K1 and the second grooved die K2. The present inventors have conducted intensive studies on the preferable conditions of the rolling molding in each of the molds. Note that the conditions of the rolling molding focused on here are “amount of reduction (amount of edging)” and “radius of curvature R at the tip of the projection”, and the amount of reduction (amount of edging) per pass is particularly important. Hereinafter, preferable conditions for the rolling molding will be described.

  First, in the method of manufacturing the H-section steel according to the present embodiment, the relationship between the wedge tip curvature radius R and the rolling load t in the second die K2 was verified. FIG. 8 is a graph showing the relationship between the wedge tip radius of curvature R and the rolling load t in the second die K2. Here, the graph of FIG. 8 shows that the slab having a width of 1800 × 300 was used as a material, the wedge angle of the second hole type K2 was 30 °, and the reduction amount per pass was 180 mm. It shows the change of the rolling load t when performing multiple pass rolling (1 pass to 5 passes) with 10 mm, 20 mm, and 30 mm.

As shown in FIG. 8, the rolling load fluctuates by changing the wedge tip radius of curvature R. For example, the rolling load t decreases as the wedge tip radius of curvature R of the second hole type K2 decreases. I understand. That is, as the wedge tip radius of curvature R of the second die K2 is reduced, the rolling load can be suppressed and the rolling shaping can be performed, so that the rolling reduction can be increased. However, the wedge tip curvature radius R has a lower limit in terms of equipment. For example, if the radius is less than 5 mm, there is a concern that the roll may be damaged.
In the rough rolling step in the production of the conventional H-section steel product, for example, a rolling load of about 300 t is applied at a rolling reduction of 65 mm, and in comparison with this, the rolling load t is reduced at a rolling reduction of 180 mm shown in FIG. The value is about 350 t to 500 t, which indicates that the rolling load is reduced under the conditions of the present invention.

FIG. 9 is a graph showing the relationship between the amount of edging per pass and the amount of buckling of the material A to be rolled in the second die K2. The graph of FIG. 9 shows that the slab having a width of 1800 × 300 was used as the material, the wedge angle of the second hole type K2 was 30 °, and the reduction amount (edging amount) per pass was 180 mm. The data are obtained when a plurality of passes (1 pass to 5 passes) are performed with R set to 10 mm, 20 mm, and 30 mm (split method R10, R20, R30 in the figure). FIG. 9 also shows the amount of buckling of the material to be rolled in the edging rolling (conventional method R20) in the conventional rough rolling process.
FIG. 10 is an explanatory diagram relating to the amount of buckling. The absolute value of ab (= | ab |) shown in FIG. 10 is the buckling amount. In addition, the buckling of the material A to be rolled as shown in FIG. Are known.

If the numerical value of the buckling amount shown in FIG. 9 is increased, the thickness of the flange portion 80 at four points varies in the subsequent process, the dimensional accuracy is reduced, and there is a possibility that the rolling cannot be continued.
As shown in FIG. 9, in the conventional rough rolling process, the rolling force has a wide range over the central portion of the material to be rolled, and is likely to be affected by a small asymmetry due to a temperature variation, a biting variation, or the like. When the rolling reduction per hit exceeds about 60 mm, there is a characteristic that the dimensional accuracy is rapidly reduced (the amount of buckling is increased).
On the other hand, when the wedge tip radius of curvature R of the second hole type K2 is set to 10 mm or 20 mm in the technology according to the present embodiment, the buckling stability is extremely low because the rolling reduction effect by edging rolling is small. It has increased and the amount of buckling has remained at a low value. Specifically, even when the edging amount per pass is 180 mm, the buckling amount is kept low and the shape is not deteriorated, so that it can be seen that stable rolling can be performed.
Further, in the technology according to the present embodiment, when the wedge tip radius of curvature R of the second hole type K2 is 30 mm, if the edging amount per pass exceeds 90 mm, the buckling amount increases, and the shape deteriorates. Becomes remarkable.

Note that the buckling amount is within an allowable range if it is within 30 mm, for example. As described above, the change in the rolling load t shown in FIG. 8 shows a result when the slab thickness is 300 mm, and produces a large final product such as a web height of 1000 mm or more and a flange width of 400 mm or more. At this time, the slab thickness is reduced to about 20 mm of the product thickness (that is, the total drawing is reduced by about 15 times). Here, since the slab thickness hardly changes in the edging rolling, the reduction of the slab thickness is mainly performed in a process after the edging finish.
On the other hand, since the tolerance of the deviation of the product corresponding to the buckling amount is, for example, about 4 mm, it is considered that the variation of the tolerance limit in the rough molding stage (rough rolling stage) is about 60 mm (4 mm × 15 times). In consideration of the process capability in this value, for example, the buckling amount allowable as industrial production is set to 30 mm or less.

As described above with reference to FIG. 9, in the technology according to the present embodiment, when the wedge tip curvature radius R of the second die K2 is 20 mm or less, the amount of buckling is suppressed and stable rolling is performed. At this time, it can be seen that the amount of reduction per pass can be arbitrarily set up to a maximum of 180 mm.
When the wedge tip radius of curvature R of the second die K2 is 30 mm or less, the rolling reduction per pass is set to a maximum of 90 mm in order to reduce the buckling amount and perform stable rolling. It turns out that it is necessary to

  That is, in the conventional rough rolling process, if the reduction amount per pass exceeds about 60 mm, it is difficult to increase the reduction amount per pass to more than 60 mm because the dimensional accuracy rapidly decreases. On the other hand, in the technology according to the present embodiment, by setting the wedge tip curvature radius R of the second hole type K2 to 20 mm or less, it is possible to expand and set the rolling reduction per pass up to 180 mm. Become. Further, by setting the wedge tip radius of curvature R of the second hole mold K2 to 30 mm or less, the amount of reduction per pass can be expanded and set to a maximum of 90 mm. Thus, by increasing the rolling reduction per pass, efficiency such as reduction in the number of passes at the time of rolling molding can be improved.

  As described above, the wedge tip radius of curvature R of the second hole type K2 is preferably set to 20 mm or less from the viewpoint of increasing the rolling reduction per pass up to 180 mm. However, as shown in FIG. 9, in the technology according to the present embodiment, even when the wedge tip radius of curvature R of the second hole type K2 is set to 30 mm, the rolling reduction per pass is increased to a maximum of 90 mm. Since the effect of reducing the amount of buckling can be seen when setting, the wedge tip curvature radius R of the second hole type K2 may be 30 mm or less.

  Here, in view of the fact that the rolling molding with the second die K2 is performed after the rolling molding with the first die K1, the wedge of the second die K2 is compared with the wedge tip radius of curvature R of the first die K1. By reducing the radius of curvature R at the tip, it is expected that the shearing effect in the rolling shaping in the second die K2 increases, and the rolling load is further reduced. For example, the rolling radius can be reduced by designing the wedge tip curvature radius R of the first die K1 to be 30 mm and the wedge tip curvature radius R of the second die K2 to be 20 mm.

In the conventional technology for manufacturing an H-section steel, unlike the method according to the present embodiment, rolling molding mainly based on shear deformation is not employed, and the entire slab width direction is reduced. Has penetrated in the center direction of the slab, and for example, buckling of the unsteady portion of the slab (particularly, the rolled end) and increase in the thickness of the web have been problems. Due to such a problem, the conventional limit of the amount of reduction per pass (rolling limit) has been less than about 70 mm.
However, as can be seen with reference to FIGS. 8 and 9, according to the method according to the present embodiment, when the wedge tip curvature radius R of the second hole type K2 is set to 20 mm or less, the reduction per pass is reduced. Even if the amount is up to 180 mm, the amount of buckling does not increase, the rolling load can be kept small, and stable and effective rolling shaping can be performed. Also, even when the rolling reduction per pass is set to a maximum of 180 mm, it can be seen that the rolling load is suppressed to about 500 t or less, so that the rolling reduction per pass is a maximum of 180 mm and a rolling load of 500 t or less. Roll molding can be performed under the following conditions.

As described above, the wedge tip in the first die K1 is related to the edging rolling on the material A to be rolled, which is performed in the die configuration described above, and particularly in the roll molding with the first die K1 and the second die K2. It is desirable that the wedge tip curvature radius R in the second hole type K2 be smaller than the curvature radius R.
In addition, in the method according to the present embodiment, the reduction amount per pass can be set to a maximum of 180 mm, and the reduction amount per pass can be set to a maximum of 180 mm. From the viewpoint that reduction is desirable in terms of rolling efficiency, it is desirable that the rolling reduction per pass be as large as possible. A specific example of the amount of reduction per pass is described in Examples described later.

  According to the method of manufacturing the H-section steel according to the present embodiment described above, the upper and lower ends (slab end faces) of the material A to be rolled are interrupted using the first to fourth hole types K1 to K4. By performing a process of bending right and left parts which are divided into right and left by these interruptions and forming a flange portion 80, the amount of reduction of the upper and lower end surfaces of the material A (slab) to be rolled can be minimized. , H-shaped raw material 13 can be formed. That is, it is possible to form the H-shaped rough material 13 by widening the flange width as compared with the conventional rough rolling method in which the slab end face is constantly reduced, and as a result, for example, the web height is 1000 mm or more, Large end products (H-section steel products) with a flange width of 400 mm or more can be manufactured.

  Further, as described above, the rolling load is reduced by making the wedge tip radius of curvature R of the second die K2 smaller than the radius of curvature R of the wedge tip of the first die K1 (for example, 30 mm or less). Even if the amount of reduction per pass is set to be increased to 180 mm at the maximum, it is possible to carry out the rolling molding without any problem. Also, since the amount of reduction per pass can be increased, the number of passes can be reduced as compared with the conventional case.

  As described above, an example of the embodiment of the present invention has been described, but the present invention is not limited to the illustrated embodiment. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the idea described in the appended claims, and these naturally belong to the technical scope of the present invention. It is understood.

  In the above-described embodiment, a technique in which the material A to be rolled is formed by using the four molds of the first mold K1 to the fourth mold K4, and thereafter, flat molding rolling is performed by using the fifth mold K5. However, the number of dies for performing the rough rolling process is not limited to this, and the rolling molding process shown in the first dies K1 to the fourth dies K4 is performed using more dies. May be. In other words, the configuration of the die shown in the above embodiment is an example, and the number of die formed in the sizing mill 3 or the rough rolling mill 4 can be arbitrarily changed, and the rough rolling process is preferably performed. It is appropriately changed to the extent that it can be performed.

  As an example of the present invention, the following verification was performed. First, as Comparative Example 1, Table 1 shows an example of a pass schedule in a case where rolling shaping is performed in the first to third dies (G1 to G3) by the conventional rough rolling method in which the end face of the slab is constantly reduced. Show. In Comparative Example 1, a slab having a width of 2300 mm was used as a raw material, and rolling molding was performed until the web height became 1200 mm, and the reduction amount per pass was 60 mm or less. As an example of the conventional rough rolling method, for example, a method utilizing the width expansion of a material to be rolled by edging rolling as described in Japanese Patent No. 3457362 is exemplified. In such a method, since the material to be rolled in the mold is poor in guideability, the amount of reduction per pass has to be limited to 60 mm or less.

  As shown in Table 1, in Comparative Example 1, rolling modeling of a total of 21 passes is required to form a material to be rolled having a predetermined web height.

  On the other hand, as Example 1, the following Table 2 shows an example of a pass schedule in a case where the rolling shaping is performed in the first die to the third die (G1 to G3) by the method described in the above embodiment. . However, from the viewpoint that the operator needs to monitor the schedule of the rolling molding, the number of passes is set to an even number of passes, and the pass schedule in Table 2 is the roll axis direction of the material to be rolled in front of the rolling mill. The schedule is configured to be changed using a device that can change the position (for example, a side guide, a manipulator, or the like). In the first embodiment, as described in the above embodiment, since a material to be rolled having a predetermined web height can be obtained from a slab having a smaller width than the conventional one, a slab having a width of 2000 mm is used as a raw material. Roll molding is performed until the thickness becomes 1200 mm.

  In the pass schedule shown in Table 2, as described in the above embodiment, the amount of reduction per pass can be increased, so that the reduction amount is set to 70 mm or more and 180 mm at the maximum in some passes. Therefore, a total of 12 passes are required to form a material to be rolled having a predetermined web height.

  In addition, as Example 2, a pass schedule in a case where the rolling shaping is performed in the first to third shaping molds (G1 to G3) by the method described in the above-described embodiment, wherein the material to be rolled is rolled. Table 3 below shows a schedule configuration in which both the front and rear surfaces of the machine are turned. In the second embodiment, for the same reason as in the first embodiment, a slab having a width of 2000 mm is used as a raw material, and rolling molding is performed until the web height becomes 1200 mm.

  In the pass schedule shown in Table 3, since the amount of reduction per pass can be increased, the reduction amount is set to a maximum of 180 mm with a reduction amount of 70 mm or more in some passes, and therefore, the material to be rolled having a predetermined web height is formed. However, there are 9 passes in total.

  Comparing Comparative Example 1 in Table 1 with Examples 1 and 2 in Tables 2 and 3, firstly, the upper and lower ends (slab end faces) of the material A to be rolled using the first to fourth hole types K1 to K4. , The width of the slab as a material can be reduced by adopting the molding of forming the flange part 80 by bending each part divided to the left and right by the interruption to the left and right. Thus, it can be seen that the number of passes is reduced. In addition, it can be seen that in Examples 1 and 2 as compared with Comparative Example 1, the amount of reduction per pass could be increased, thereby further reducing the number of passes.

Further, in the method of manufacturing the H-section steel according to the above-described embodiment, the shape of the flange portion 80 of the rough-rolled material A to be rolled is changed to the shape of the flange portion before flat-hole molding in the conventional manufacturing method. In comparison, the shape is close to the shape of the product flange. This is due to the adoption of a shaping technology that bends a divided portion (flange portion 80) formed by inserting an interrupt without changing the end shape of the material (slab) having a rectangular cross section used as the material. to cause.
Therefore, compared with the conventional manufacturing method, the thickness of the web for flowing the metal flow into the flange portion 80 is not significantly required to be reduced.
The thickness reduction of the web is mainly performed in the flat molding die (fifth die K5 according to the above-described embodiment). Here, a specific example of the pass schedule of the flat molding is described as a comparative example. 2, described as Example 3.

  Comparative Example 2 shown in Table 4 below is an example of a pass schedule in a case where a 300-mm thick slab is used as a raw material in a flat molding hole die (G4) and a material to be rolled having a web thickness of 300 mm is reduced to a web thickness of 70 mm. It is. As shown in Table 4, particularly in the latter pass, the web draft is increased, so the reaction force is increased, and the reduction amount per pass has to be reduced. For example, the reduction amount per pass is about 5 mm. It becomes. As a result, the number of passes increases, and the schedule in Table 4 has 17 passes.

  On the other hand, Example 3 shown in Table 5 below shows a pass schedule in the case where a 300 mm thick slab is used as a raw material in a flat molding hole die (G4) and a material to be rolled having a web thickness of 300 mm is reduced to a web thickness of 100 mm. This is an example. The schedule shown in Table 5 is flat shaping rolling in the case where the method for manufacturing an H-section steel according to the above embodiment is adopted, and it is not required to reduce the web thickness to 70 mm. Therefore, the number of passes is limited to 12 passes.

  As described above, Tables 1 to 5 show specific examples of the pass schedules according to Comparative Examples 1 and 2 and Examples 1 to 3. According to this, if the conventional rough rolling method of constantly reducing the end face of the slab is adopted, 38 passes, which is the number of passes obtained by adding the comparative example 1 and the comparative example 2, are required. On the other hand, when the method of manufacturing the H-section steel according to the present invention described in the above embodiment is adopted, 24 passes, which is the number of passes obtained by adding the first and third embodiments, or the second embodiment and the third embodiment are added. It can be seen that the rough rolling process can be completed in 21 passes, which is the number of passes. From these results, according to the method of manufacturing an H-section steel according to the present invention, it is possible to realize a reduction in the number of passes at the time of rolling molding as compared with the conventional method, and to efficiently and stably manufacture an H-section steel product having a large flange width. It is shown that you can.

  INDUSTRIAL APPLICABILITY The present invention is applicable to, for example, a manufacturing method of manufacturing an H-section steel using a slab having a rectangular cross section as a raw material.

DESCRIPTION OF SYMBOLS 1 ... Rolling equipment 2 ... Heating furnace 3 ... Sizing mill 4 ... Rough rolling mill 5 ... Intermediate universal rolling mill 8 ... Finishing universal rolling mill 9 ... Edger rolling mill 11 ... Slab 13 ... H-shaped rough shaped material 14 ... Intermediate material 16 ... H-shaped steel products 20 ... Top hole type roll (first hole type)
21 ... pilot hole type roll (first hole type)
25, 26: Projecting portion (first hole type)
28, 29 ... Interruption (1st hole type)
30 ... Top hole type roll (second hole type)
31 ... pilot hole type roll (second hole type)
35, 36 ... Projection (second hole type)
38, 39 ... Interruption (2nd hole type)
40 ... Top hole type roll (third hole type)
41 ... pilot hole type roll (third hole type)
45, 46... Projection (third hole type)
48, 49… Interruption (3rd hole type)
50 ... Top hole type roll (4th hole type)
51 ... pilot hole type roll (fourth hole type)
55, 56: Projection (fourth hole type)
58, 59: Interruption (4th hole type)
80: flange portion 82: web portion 85: upper hole type roll (fifth hole type)
86 ... pilot hole type roll (fifth hole type)
K1 ... first hole type K2 ... second hole type K3 ... third hole type K4 ... fourth hole type K5 ... fifth hole type (flat molding hole type)
T: Production line A: Rolled material

Claims (3)

A method for producing an H-section steel comprising a rough rolling step, an intermediate rolling step, and a finish rolling step,
A rolling mill that performs the rough rolling process on a rectangular cross-section material is engraved with a plurality of four or more molds for forming a material to be rolled,
In the plurality of molds, one or more passes of the material to be rolled are formed,
The first and second molds among the plurality of molds are formed with a protrusion for vertically interrupting the width direction of the material to be rolled,
In the shaping in the second mold, shaping is performed to increase the depth of interruption formed in the first mold,
In the third and subsequent molds of the plurality of molds, a step of sequentially bending the divided portion formed by the interruption is performed,
The H-shaped steel is characterized in that the tip angle of the projection formed in the second mold is not less than 25 ° and not more than 40 °, and the tip radius of curvature of the projection is designed to be 30 mm or less. Production method. When the radius of curvature of the tip of the protrusion formed in the second mold is designed to be 20 mm or less, the rolling reduction per rolling molding pass in the second mold is set to a maximum of 180 mm. The method for producing an H-section steel according to claim 1. When the radius of curvature of the tip of the protrusion formed in the second mold is designed to be 30 mm or less, the rolling reduction per rolling molding pass in the second mold is set to a maximum of 90 mm. The method for producing an H-section steel according to claim 1 or 2, wherein: