JP2018008279A - Manufacturing method of h-shaped steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and stably manufacture an H-shaped steel product larger in a flange width than usual, by restraining the occurrence of shape failure in a rolled material.SOLUTION: A projection part for vertically interrupting to the width direction of a rolled material, is formed in a first caliber and a second caliber among a plurality of calibers, and draft is execute in a state of contacting an end surface of the rolled material and a caliber peripheral surface in molding of at least one path or more on and after the second caliber among the plurality of calibers, and a bending molding process is executed for successively bending a divided part molded by interruption on and after a third caliber among the plurality of calibers, and when a thickness of a rectangular cross-sectional raw material is 290 mm-310 mm, the flange width expansion ratio being the ratio of a rolled material flange width after molding in the second caliber and a rolled material flange width in the final shape of the bending molding process is determined by the following expression (2). The flange width expansion ratio=a×Δθ+b...(2).SELECTED DRAWING: Figure 9

Description

  The present invention relates to a manufacturing method for manufacturing H-section steel using, for example, a slab having a rectangular cross section as a raw material.

  When manufacturing H-section steel, raw materials such as slabs and blooms extracted from a heating furnace are formed into a rough shape (so-called dogbone-shaped material to be rolled) by a roughing mill (BD), and intermediate universal rolling is performed. The thickness of the rough profile web and flange is reduced by a machine, and the edge reduction mill near the intermediate universal rolling mill is subjected to width reduction and forging and shaping of the flange of the material to be rolled. . And an H-section steel product is modeled by a finishing universal rolling mill.

  In such a method for manufacturing an H-shaped steel, when forming a so-called dogbone-shaped rough shape material from a slab material having a rectangular cross section, an interruption was applied to the slab end face in the first hole mold of the rough rolling process. Thereafter, a technique is known in which the interrupt is widened in the second and subsequent hole molds, or the interrupt depth is increased, and the interrupt of the slab end face is erased in the subsequent hole molds (see, for example, Patent Document 1). ).

  Further, for example, Patent Document 2 discloses a technique in which an interruption is applied to the end face of the slab and the interruptions are gradually deepened and then expanded in a box hole type to form a flange-corresponding portion of H-shaped steel.

JP-A-7-88501 Japanese Patent Laid-Open No. 60-21101

  In recent years, with the increase in size of structures and the like, production of large H-shaped steel products has been desired. In particular, a product having a wider flange than the conventional one that greatly contributes to the strength and rigidity of the H-shaped steel is desired. 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 that of the prior art from modeling in the rough rolling process.

  However, for example, in the technique disclosed in Patent Document 1 described above, in the method of interrupting the end face of a material such as a slab (slab end face), edging the end face, and performing rough rolling using the width expansion, There is a limit to widening the flange. That is, in order to increase the width of the flange in the conventional rough rolling method, the width can be improved by techniques such as wedge design (interrupt angle design), reduction adjustment, and lubrication adjustment. Since it does not contribute significantly, the width expansion ratio indicating the ratio of the flange width expansion amount to the edging amount is about 0.8 even under the highest efficiency in the initial stage of edging. Under repeated conditions, it is known that the flange width decreases as the amount of expansion increases, and finally becomes about 0.5. In addition, it is conceivable to increase the edging amount of the material itself such as the slab, but there is an equipment limit on the equipment size, reduction amount, etc. of the roughing mill, so that it is not possible to realize a sufficiently wide product flange. There are circumstances.

  Further, for example, in the technique disclosed in Patent Document 2, edging rolling is immediately applied to a material such as an interrupted slab by using a box hole mold having a flat bottom surface without particularly changing the shape of the interrupt. The flange equivalent part is modeled, and in such a method, a shape defect associated with abruptly changing the shape of the material to be rolled tends to occur. In particular, the shape change of the material to be rolled in such shaping is determined by the relationship between the force of the contact portion between the material to be rolled and the roll and the bending rigidity of the material to be rolled, and has a larger flange width than conventional. When manufacturing H-section steel, there exists a problem that a shape defect tends to arise more.

  In view of the above circumstances, the object of the present invention is to deeply interrupt with a protrusion having an acute tip shape on the end face of a rectangular cross-section material such as a slab in a rough rolling process using a hole mold when manufacturing H-section steel. It is possible to efficiently and stably manufacture H-shaped steel products with a larger flange width than before, by suppressing the occurrence of shape defects in the material to be rolled by sequentially bending the flange portions formed thereby. Another object of the present invention is to provide a method for manufacturing such an H-shaped steel.

In order to achieve the above object, according to the present invention, there is provided a method for producing an H-section steel comprising a rough rolling step, an intermediate rolling step, and a finish rolling step, wherein the rough rolling step is performed on a rectangular cross-section material. The machine is engraved with a plurality of four or more hole molds for modeling the material to be rolled. In the plurality of hole molds, one or a plurality of passes of the material to be rolled are formed, and the first of the plurality of hole molds. The hole mold and the second hole mold are formed with protrusions that interrupt vertically with respect to the width direction of the material to be rolled. The rolling is performed in a state where the end face of the rolled material and the peripheral surface of the hole mold are in contact with each other, and the divided holes formed by the interruption are sequentially bent after the third hole mold among the plurality of hole molds. The thickness of the rectangular cross-section material is 290 mm or more and 310 m In the case of the following, the flange width expansion ratio, which is the ratio of the rolled material flange width after shaping in the second hole mold and the rolled material flange width in the final shape of the bending shaping process, is expressed by the following equation: There is provided a method for producing an H-section steel characterized by being defined in (2).
Flange width expansion ratio = a × Δθ + b (2)
However, a and b are predetermined constants, and Δθ is a bending angle in the bending modeling step.

  The plurality of hole molds are four hole molds of a first hole mold to a fourth hole mold for modeling a material to be rolled, and among the plurality of hole molds, the third hole mold and the fourth hole mold include: A protrusion that bends the divided part by pressing against the divided part is formed, and a tip angle of the protruding part formed in the first hole mold and the second hole mold is 25 ° or more and 40 ° or less, The flange width expansion rate may be determined based on the formula (2) within a range where the bending angle Δθ in the bending modeling process in the three-hole mold and / or the fourth hole mold is 30 ° or more and 150 ° or less. .

Based on the flange width expansion rate defined by the equation (2), the value of the flange width of the material to be rolled after the folding modeling process is predicted, and the predicted flange width of the material to be rolled and the bending modeling process are performed. The hole flange width of the fourth hole mold may be designed so that the relationship with the fourth hole mold satisfies the following expression (3).
Predicted bending hole flange width−hole flange width = c × θ−d (3)
However, c and d are predetermined constants, and θ is the tip angle of the protrusion formed in the fourth hole mold.

  According to the present invention, in a rough rolling process using a hole mold when manufacturing an H-section steel, a deep-interrupted protrusion is formed on an end face of a rectangular cross-section material such as a slab, thereby forming By sequentially bending the formed flange portions, it is possible to suppress the occurrence of shape defects in the material to be rolled, and to efficiently and stably manufacture H-shaped steel products having a larger flange width than in the past.

It is a schematic explanatory drawing about the production line of H-section steel. It is a schematic explanatory drawing of a 1st hole type | mold. It is a schematic explanatory drawing of a 2nd hole type | mold. It is a schematic explanatory drawing of a 3rd hole type | mold. It is a schematic explanatory drawing of a 4th hole type | mold. It is a schematic explanatory drawing explaining the mode of modeling in the 2nd hole type. It is a graph which shows the relationship between a bending angle and a flange width expansion rate. It is the analysis figure which performed the comparison of the flange width in the case where bending modeling is made into two steps, and the case where it made it into three steps. The horizontal axis is the wedge angle of the folding hole mold, and the vertical axis is the difference between the predicted flange width value after bending and the hole width setting value of the actually designed folding hole mold. It is the graph which evaluated rolling stability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, components having substantially the same functional 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 roughing mill 4, an intermediate universal rolling mill 5, and a finishing universal rolling mill 8 are arranged in order from the upstream side on the production line T. Further, an edger rolling mill 9 is provided in the vicinity of the intermediate universal rolling mill 5. In the following description, the steel materials in the production line T will be collectively referred to as “rolled material A” for the sake of explanation, and the shape may be appropriately illustrated using broken lines, diagonal lines, etc. in each drawing.

  As shown in FIG. 1, in the production line T, a material A to be rolled such as a slab 11 extracted from the heating furnace 2 is roughly rolled in a sizing mill 3 and a roughing mill 4. Next, intermediate rolling is performed in the intermediate universal rolling mill 5. During the intermediate rolling, the edger rolling machine 9 applies a reduction to the end of the material to be rolled (flange corresponding portion 12) as necessary. Usually, the rolls of the sizing mill 3 and the roughing mill 4 are engraved with about 4 to 6 hole shapes in total, and the H-shaped rough profile is formed by reverse rolling in a plurality of passes via these. 13 is formed, and the H-shaped rough material 13 is subjected to a plurality of passes of rolling by using a rolling mill row composed of two rolling mills of the intermediate universal rolling mill 5-edger rolling mill 9. Modeled. Then, the intermediate material 14 is finish-rolled into a product shape in the finish universal rolling mill 8 to produce an H-section steel product 16.

  Here, the slab width T of the slab 11 extracted from the heating furnace 2 is, for example, in a range of 290 mm to 310 mm. This is a slab size used when manufacturing a general H-shaped steel product.

  Next, the hole configuration and the hole shape formed in the sizing mill 3 and the roughing mill 4 shown in FIG. 1 will be described with reference to the drawings. In addition, in addition to the 1st hole type-4th hole type demonstrated below, the rough rolling mill 4 usually uses the so-called dogbone-shaped H-shaped rough shape material for the material A to be rolled. A hole type 13 is further provided. Since this hole type is already known, illustration and description in this specification will be omitted. The heating furnace 2, the intermediate universal rolling mill 5, the finishing universal rolling mill 8, the edger rolling mill 9 and the like in the production line T are general apparatuses conventionally used for manufacturing H-section steel. Since the configuration and the like are known, the description is omitted in this specification.

  2-5 is a schematic explanatory drawing about the hole type | mold engraved in the sizing mill 3 and the rough rolling mill 4 which perform a rough rolling process. Here, the first hole type to the fourth hole type to be described may be all engraved in the sizing mill 3, for example, and the four types of the first hole type to the fourth hole type may be provided in the sizing mill 3 and the roughing mill 4. The hole mold may be engraved separately. That is, the first hole type to the fourth hole type may be engraved over both the sizing mill 3 and the rough rolling mill 4, or may be engraved in either one of the rolling mills. In the rough rolling process in the manufacture of normal H-section steel, modeling is performed in one or a plurality of passes in each of these perforations.

  Further, in the present embodiment, a case where there are four hole types engraved will be described as an example. However, the number of hole types is not necessarily a four-hole type, and the number of hole types is not less than four. It may be. In other words, any hole configuration suitable for modeling the H-shaped rough member 13 may be used. 2 to 5, the approximate final path shape of the material A to be rolled at the time of shaping in each hole mold is illustrated by a broken line.

  FIG. 2 is a schematic explanatory view of the first hole mold K1. The first hole mold K1 is engraved in the upper hole roll 20 and the lower hole roll 21 which are a pair of horizontal rolls, and the material A to be rolled is placed in the roll gap between the upper hole roll 20 and the lower hole roll 21. Reduced and shaped. Further, on the peripheral surface of the upper hole type roll 20 (that is, the upper surface of the first hole type K1), a protruding portion 25 that protrudes toward the inside of the hole type is formed. Further, a projection 26 is formed on the peripheral surface of the lower hole roll 21 (that is, the bottom surface of the first hole mold K1) protruding toward the inside of the hole mold. These projecting portions 25 and 26 have a tapered shape, and the projecting length and other dimensions are equal between the projecting portion 25 and the projecting portion 26. The height (projection length) of the protrusions 25 and 26 is h1, and the tip angle is θ1a.

  In the first hole mold K1, the protrusions 25 and 26 are pressed against the upper and lower ends (slab end surfaces) of the material A to be rolled, and interrupts 28 and 29 are formed. Here, the tip end angle (also referred to as wedge angle) θ1a of the protrusions 25 and 26 is preferably, for example, 25 ° or more and 40 ° or less.

  Here, the hole width of the first hole mold K1 is preferably substantially equal to the thickness of the material A to be rolled (that is, the slab thickness). Specifically, by making the hole mold width and the slab thickness the same at the tip portions of the projections 25 and 26 formed in the first hole mold K1, the right and left centering property of the material A to be rolled is suitably obtained. Secured. Moreover, by setting it as such a hole-type dimension, as shown in FIG. 2, at the time of modeling with the 1st hole type K1, in the upper-lower-end part (slab end surface) of the to-be-rolled material A, the said protrusion The first holes are formed on the upper and lower ends of the slabs, which are partly in contact with the material A to be rolled, and divided into four elements (parts) by interruptions 28 and 29. It is preferable that no positive reduction is performed on the top and bottom surfaces of the mold K1. This is because the reduction by the top and bottom surfaces of the hole mold causes the material A to be elongated in the longitudinal direction, thereby reducing the generation efficiency of the flange (flange portion 80 described later). That is, in the first hole type K1, the protrusions 25 and 26 are pressed against the upper and lower ends (slab end surfaces) of the material A to be rolled, and the reduction in the protrusions 25 and 26 when the interrupts 28 and 29 are formed. The amount (wedge tip reduction amount ΔT) is sufficiently larger than the reduction amount (slab end surface reduction amount ΔE) at the upper and lower ends of the slab, whereby interrupts 28 and 29 are formed.

  FIG. 3 is a schematic explanatory diagram of the second hole mold K2. The 2nd hole type | mold K2 is engraved by the upper hole type | mold roll 30 and the lower hole type | mold 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 protruding portion 35 that protrudes toward the inside of the hole type is formed. Further, a projection 36 that protrudes toward the inside of the hole mold is formed on the peripheral surface of the lower hole roll 31 (that is, the bottom surface of the second hole mold K2). These projecting portions 35 and 36 have a tapered shape, and the projecting length and other dimensions are configured to be equal between the projecting portion 35 and the projecting portion 36. It is desirable that the tip end angle of the projections 35 and 36 is a wedge angle θ1b of 25 ° or more and 40 ° or less.

  The wedge angle θ1a of the first hole mold K1 is preferably the same angle as the wedge angle θ1b of the second hole mold K2 in the subsequent stage in order to enhance the inductivity and ensure the stability of rolling.

  Further, 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 mold K1, and h2> h1. Here, as described above, the tip angle (wedge angle θ1b) of the projections 35 and 36 is the same as the tip angle of the projections 25 and 26 of the first hole mold K1 (that is, θ1a = θ1b). It is preferable. In the roll gap between the upper hole roll 30 and the lower hole roll 31, the material A to be rolled after the first hole K1 passing material is further shaped.

Here, the height h2 of the protrusions 35 and 36 formed on the second hole mold K2 is higher than the height h1 of the protrusions 25 and 26 formed on the first hole mold K1, and the material A to be rolled A Similarly, the length of penetration into the upper and lower ends (slab end face) of the second hole mold K2 is longer. The penetration depth of the projections 35 and 36 into the material to be rolled A in the second hole mold K2 is the same as the height h2 of the projections 35 and 36. That is, the penetration depth h1 ′ of the protrusions 25 and 26 into the rolled material A in the first hole mold K1, and the penetration depth of the protrusions 35 and 36 into the rolled material A in the second hole mold K2. h2 has a relationship of h1 ′ <h2.
Further, an angle θf formed by the hole top surfaces 30a and 30b and the hole bottom surfaces 31a and 31b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the protrusions 35 and 36 is shown in FIG. The four locations shown are each configured at about 90 ° (substantially at right angles).

  As shown in FIG. 3, since the intrusion length of the protrusion when pressed against the upper and lower ends (slab end face) of the material A is long, in the second hole type K2, the first hole type K1. Modeling is performed so that the interrupts 28 and 29 formed in step 1 are further deepened, and interrupts 38 and 39 are formed.

In addition, the second hole mold K2 shown in FIG. 3 is formed by multiple passes, and at least one of the multiple pass formations includes the upper and lower ends (slab end surfaces) of the material to be rolled A and the hole mold. The inside (the upper surface and the bottom surface of the second hole mold K2) needs to be in contact. However, it is not desirable that all the passes are in contact. For example, the upper and lower ends (slab end surface) of the material A to be rolled contact with the inside of the hole mold only in the final pass, and the slab end surface reduction amount ΔE is a positive value. (ΔE> 0) is desirable. This is because when the upper end of the material A to be rolled and the inside of the hole mold are not in contact with each other in the second hole mold K2, a flange equivalent part (a flange part 80 to be described later) is shaped asymmetrically. This is because a shape defect such as this may occur, and there is a problem in terms of material permeability.
On the other hand, in the other passes, the hole mold and the material to be rolled A are not in contact with each other except for the projections 35 and 36 at the upper and lower end portions (slab end surfaces) of the material to be rolled A. Material A is not actively reduced. This is because the rolling causes elongation of the material A to be rolled in the longitudinal direction and reduces the generation efficiency of a flange-corresponding portion (corresponding to a flange portion 80 described later).

  That is, in multi-pass modeling with the second hole mold K2, the upper and lower ends (slab end surfaces) of the material A to be rolled are brought into contact with the inside of the hole mold in the minimum necessary path (for example, only the final path) to perform the reduction. In other passes, it is preferable to set a pass schedule that does not perform active reduction. Also in the second hole mold K2, similarly to the first hole mold K1, the amount of reduction at the protrusions 35 and 36 (wedge tip reduction amount ΔT) is the amount of reduction at the upper and lower ends of the slab (slab end surface reduction amount ΔE). Which is sufficiently larger than this, and interrupts 38 and 39 are formed. The second hole type K2 is also referred to as “interrupt hole type” because it is a hole type that forms the interrupts 38 and 39 in this way.

  FIG. 4 is a schematic explanatory diagram of the third hole mold K3. The third hole type K3 is engraved in the upper hole type roll 40 and the 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 protrusion 45 that protrudes toward the inside of the hole type is formed. Further, a projection 46 is formed on the peripheral surface of the lower hole roll 41 (that is, the bottom surface of the third hole mold K3) protruding toward the inside of the hole mold. The protrusions 45 and 46 have a tapered shape, and the protrusion 45 and the protrusion 46 have the same dimensions such as the protrusion length.

The tip end angle θ2 of the projections 45 and 46 is configured to be wider than the angle θ1b, and the penetration depth h3 of the projections 45 and 46 into the material to be rolled A is the penetration depth of the projections 35 and 36. The length is shorter than h2 (that is, h3 <h2). Further, the tip end angle θ2 of the protrusions 45 and 46 is desirably 70 ° or more and 110 ° or less.
Further, an angle θf formed by the hole top surfaces 40a and 40b and the hole bottom surfaces 41a and 41b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the protrusions 45 and 46 is shown in FIG. The four locations shown are each configured at about 90 ° (substantially at right angles).

  As shown in FIG. 4, in the 3rd hole type | mold K3, it forms in the 2nd hole type | mold K2 in the upper and lower end part (slab end surface) of the to-be-rolled material A with respect to the to-be-rolled material A after 2nd hole type | mold K2 passing material. The interrupts 38 and 39 thus generated become interrupts 48 and 49 when the projections 45 and 46 are pressed against each other. That is, in the final pass in modeling with the third hole mold K3, the deepest part angle of the interrupts 48 and 49 (hereinafter also referred to as the interrupt angle) is θ2. In other words, in the second hole type K2, modeling is performed such that a divided part (a part corresponding to a flange part 80 described later, also referred to as a flange-corresponding part) formed with the interruptions 38 and 39 is bent outward. Is called.

In addition, the shaping with the third hole mold K3 shown in FIG. 4 is performed by at least one pass, and at least one of these passes is the upper and lower ends (slab end surface) of the material A to be rolled and the inside of the hole mold (second The top surface and bottom surface of the three-hole type K3 must be in contact. However, it is not desirable that all the passes are in contact. For example, the upper and lower ends (slab end surface) of the material A to be rolled contact with the inside of the hole mold only in the final pass, and the slab end surface reduction amount ΔE is a positive value. (ΔE> 0) is desirable. This is because when the upper limit end of the material A to be rolled and the inside of the hole mold are not in contact with each other in the third hole mold K3, a flange-corresponding portion (flange portion 80 described later) is shaped asymmetrically. This is because a shape defect such as this may occur, and there is a problem in terms of material permeability.
On the other hand, in the other passes, the hole mold and the material to be rolled A are not in contact with each other except for the protrusions 45 and 46 at the upper and lower end portions (slab end surfaces) of the material to be rolled A. Material A is not actively reduced. This is because the rolling causes elongation of the material A to be rolled in the longitudinal direction and reduces the generation efficiency of a flange-corresponding portion (corresponding to a flange portion 80 described later).

  FIG. 5 is a schematic explanatory view of the fourth hole type K4. The 4th hole type | mold K4 is engraved by the upper hole type | mold roll 50 and the lower hole type | mold roll 51 which are a pair of horizontal rolls. On the peripheral surface of the upper hole roll 50 (that is, the upper surface of the fourth hole mold K4), a protrusion 55 is formed that protrudes toward the inside of the hole mold. Further, a projection 56 that protrudes toward the inside of the hole mold is formed on the peripheral surface of the lower hole roll 51 (that is, the bottom surface of the fourth hole mold K4). These projecting portions 55 and 56 have a tapered shape, and the projecting length and other dimensions are configured to be equal between the projecting portion 55 and the projecting portion 56.

The tip end angle θ3 of the projections 55 and 56 is configured to be wider than the angle θ2, and the penetration depth h4 of the projections 55 and 56 into the rolled material A is the penetration depth of the projections 45 and 46. The length is shorter than h3 (that is, h4 <h3). Further, it is desirable that the tip end portion angle θ3 of the protrusions 55 and 56 is 130 ° or more and 170 ° or less.
Further, the angle θf formed by the hole top surfaces 50a and 50b and the hole bottom surfaces 51a and 51b facing the upper and lower ends (slab end surfaces) of the material A to be rolled and the inclined surfaces of the protrusions 55 and 56 is the third angle. As with the hole type K3, the four locations shown in FIG. 5 are each configured at about 90 ° (substantially perpendicular).

In the fourth hole mold K4, the interruptions 48 and 49 formed in the third hole mold K3 at the upper and lower end portions (slab end surfaces) of the material A to be rolled with respect to the material A to be rolled after passing the third hole mold K3. When the projections 55 and 56 are pressed against each other, they are expanded and interrupts 58 and 59 are generated. That is, in the final pass in modeling with the fourth hole mold K4, the deepest part angle of the interrupts 58 and 59 (hereinafter also referred to as the interrupt angle) is θ3. In other words, in the third hole mold K3, there is a modeling in which a divided part (a part corresponding to a flange part 80 to be described later, also referred to as a flange equivalent part) formed along with the formation of the interrupts 48 and 49 is further bent outward. Done. The portions of the upper and lower end portions of the material A to be rolled thus formed are portions corresponding to the flanges of the subsequent H-shaped steel product, and are referred to as flange portions 80 here.
In addition, since the 3rd hole type | mold K3 and the 4th hole type | mold K4 demonstrated above shape the flange part 80 by bending modeling, they are also called a "folding hole type."

  The interrupt angle θ3 of the fourth hole type K4 is desirably set to an angle slightly smaller than 180 °, and is set to an angle of 130 ° to 170 °, for example. This is because if the interruption angle θ3 is set to 180 °, when the web thickness is reduced in the flat shaping hole mold which is the next process, the outside of the flange portion 80 is expanded, and in the rolling with the flat shaping hole mold, This is because the protrusion is likely to occur. That is, since the amount of expansion on the outside of the flange portion 80 is determined according to the shape of the flat shaping hole mold and the web thickness reduction in the next process, the interrupt angle θ3 here is the shape and web thickness of the flat shaping hole mold. It is desirable that the amount is suitably determined in consideration of the amount of reduction.

Further, the modeling with the fourth hole mold K4 shown in FIG. 5 is performed by at least one pass or more, and at least one or more of the multi-pass modeling includes the upper and lower ends (slab end face) and the hole of the material A to be rolled. The inside of the mold (the upper surface and the bottom surface of the fourth hole mold K4) needs to be in contact. However, it is not desirable that all the passes are in contact. For example, the upper and lower ends (slab end surface) of the material A to be rolled contact with the inside of the hole mold only in the final pass, and the slab end surface reduction amount ΔE is a positive value. (ΔE> 0) is desirable. This is because when the upper limit end of the material A to be rolled and the inside of the hole mold are not in contact with each other in the fourth hole mold K4, a flange-corresponding portion (a flange portion 80 described later) is shaped asymmetrically. This is because a shape defect such as this may occur, and there is a problem in terms of material permeability.
On the other hand, in the other passes, the hole mold and the material to be rolled A are not in contact with each other except for the projections 55 and 56 at the upper and lower ends (slab end surfaces) of the material to be rolled A. Material A is not actively reduced. This is because the rolling material A is elongated in the longitudinal direction and the generation efficiency of the flange portion 80 is lowered.

  The material A to be rolled formed by the first hole mold K1 to the fourth hole mold K4 described above is further reduced and formed using a known hole mold, and the H-shaped rough shape which is a so-called dogbone shape. The material 13 is shaped. Usually, after this, the web thickness is reduced by a flat shaping hole mold which reduces the thickness corresponding to the slab thickness. Thereafter, using a rolling mill row composed of two rolling mills of the intermediate universal rolling mill 5-edger rolling mill 9 shown in FIG. Then, the intermediate material 14 is finish-rolled into a product shape in the finish universal rolling mill 8 to produce an H-section steel product 16.

  As described above, the upper and lower ends (slab end surfaces) of the material A to be rolled are interrupted using the first hole mold K1 to the fourth hole mold K4 according to the present embodiment, and each divided into right and left by these interrupts. Forming the H-shaped rough shape 13 without substantially rolling down the upper and lower end surfaces of the material A (slab) to be rolled by forming the flange portion 80 by performing a process of bending the portion left and right. It can be carried out. That is, compared with the conventional rough rolling method in which the end face of the slab is always squeezed, the flange width can be widened to form the H-shaped rough shape 13, and as a result, a final product having a large flange width ( H-shaped steel) can be manufactured. In addition, since the H-shaped rough shape 13 can be formed without being affected by the apparatus limit in the amount of reduction or equipment size in the sizing mill 3 or the rough rolling mill 4, the slab size of the material is conventionally reduced. In comparison, the size can be reduced (the slab width can be reduced), and a final product having a large flange width can be efficiently manufactured.

By the way, in the present embodiment, the wedge angle θ2 of the third hole mold K3 (the tip angle θ2 of the protrusions 45 and 46) is set to 70 ° to 110 °, and the wedge angle θ3 of the fourth hole mold K4. By constructing (the tip portion angle θ3 of the protrusions 55 and 56) to be 130 ° or more and 170 ° or less, the flange-corresponding portion (the rear flange portion 80) of the material A is rolled.
As a result of intensive studies on the so-called folding modeling performed in the third hole mold K3 and the fourth hole mold K4, the present inventors have found that the deformation of the portion corresponding to the flange of the material A to be rolled is performed in these folding modeling. It has been found that bending deformation becomes dominant, a tensile force acts on the outer surface portion of the flange contacting the roll (hole type), and a compressive force acts on the inner surface portion of the flange. According to such a tensile force and compressive force, it was found that the width and length of the flange-corresponding portion (hereinafter also simply referred to as the flange width) is expanded according to the bending angle in the folding modeling.

On the other hand, as described above, in the rolling modeling with the third hole mold K3 and the fourth hole mold K4, from the viewpoint of material permeability, the upper and lower ends of the material A to be rolled by rolling modeling of at least one pass ( The slab end face) and the inside of the hole mold (the upper surface and the bottom surface of the hole mold) are required to be in contact with each other.
That is, in the rolling modeling in the third hole mold K3 and the fourth hole mold K4 according to the present embodiment, while considering the expansion of the flange width, and from the viewpoint of ensuring the material permeability and flange dimension accuracy, It is required to realize a hole design in which the upper and lower ends of the material A to be rolled are brought into contact with the inside of the hole mold and the flange width is maximized as much as possible.

Therefore, in the following, conditions for the hole dimensions that are suitably designed based on the above-described knowledge will be described with reference to the drawings. First, the definition of the interrupt line length L that is the basis of the flange width will be described. FIG. 6 is a schematic explanatory view for explaining the modeling in the second hole mold K2, and is an enlarged view of a part (upper half) of FIG. Specifically, the upper half of the second hole mold K2 shown in FIG. 3 is enlarged and illustrated.
As shown in FIG. 6, the width of the flange equivalent part (the rear flange part 80), that is, the flange width is determined based on the length of the interrupt line length L of the interrupt 38. The interrupt line length L is the sum of the lengths L1 and L3 of the straight line portions on the side walls on both sides of the interrupt 38 and the curve length L2 of the portion having the curvature at the depth end of the interrupt 38. That is, L = L1 + L2 + L3.

  In the bending modeling in the third hole mold K3, modeling is performed while the interruption line length L is enlarged. Furthermore, in the bending modeling in the fourth hole mold K4, the flange equivalent part bent in the third hole mold K3 is further bent. The inventors of the present invention analyzed to find a predetermined law in the extension of the interrupt line length L, and obtained the knowledge described below with reference to FIG.

FIG. 7 shows a case where the interrupts 38 and 39 formed in the modeling with the second hole mold K2 are expanded by the folding modeling with one or a plurality of folding hole molds (for example, the third hole mold K3 and the fourth hole mold K4). It is a graph which shows the relationship between bending angle (DELTA) (theta) (angle change amount (DELTA) (theta) by a projection part), and a flange width expansion rate. FIG. 7 shows a case where the thickness of the material slab is about 300 mm (290 mm to 310 mm), and a case where the bending angle is in the range of about 30 ° to 150 °.
The flange width expansion rate is the ratio of the flange width (interrupt line length) after the rolling modeling finish in the second hole type K2 (interrupt hole type) and the flange width (interrupt line length) after bending modeling. It is a value shown by the following formula (1).
Flange width expansion ratio = Folded hole type finished width / Interrupt hole type finished width (1)

As shown in FIG. 7, when the material slab thickness is 300 mm within the range of the bending angle Δθ of about 30 ° to 150 °, the flange width expansion rate increases almost in proportion to the bending angle. That is, the flange width expansion rate can be expressed by the following equation (2) when the slope a and the intercept b are given as predetermined constants in the graph shown in FIG.
Flange width expansion ratio = a × Δθ + b (2)

  In addition, the data shown in FIG. 7 does not depend on the number of hole molds to be folded, but the general case where the bending is performed by various methods such as one stage, two stages, or three stages or more. It is data. Specifically, for example, the present invention can also be applied to a case where folding modeling is performed in two stages of the third hole mold K3 and the fourth hole mold K4 according to the present embodiment. For example, it may be performed in three stages. In that case, in addition to the hole mold configuration according to the present embodiment, the number of hole molds to be bent is increased by one.

  FIG. 8 is an analysis diagram in which the flange width is compared between the case where the bending modeling is performed in two stages and the case where the folding modeling is performed in three stages. The broken line shown in FIG. 8 indicates the case where the folding modeling is in two stages, and the solid line indicates the case where the bending modeling is in three stages. The rolling conditions in FIG. 8 are the case where the amount of reduction at the tip of the wedge (projection) is 900 mm, and the folding modeling in two stages is performed at a folding angle of 30 °, 90 °, 120 °, and in three stages. The folding modeling is performed when the bending angles are 30 °, 60 °, 90 °, and 120 °. In addition, the analysis figure shown in FIG. 8 expands and shows the 1/4 cross section of a to-be-rolled material.

  As shown in FIG. 8, the shape of the rolled material of the broken line and the shape of the rolled material of the solid line are substantially the same shape, and it is considered that the influence on the flange width due to the number of stages of bending shaping is extremely small. From this result, in the rough rolling process according to the present embodiment, the wedge angle of the interrupt hole type (first hole type K1 and second hole type K2) is designed to be a predetermined angle, for example, 25 ° to 40 °. Thus, it is presumed that the H-shaped rough shaped member 13 having a constant flange width is formed regardless of the progress (number of steps, etc.) in the bending modeling.

  As described above, when the material slab thickness is 300 mm, the flange width expansion rate increases substantially in proportion to the bending angle, so that the flange width value after the bending modeling is a predictable value (see FIG. 7). That is, based on such characteristics, the flange width after bending modeling is predicted, and based on the predicted value, the front end (slab end surface) of the flange-corresponding portion and the inside of the hole mold (over the entire length in the longitudinal direction of the material A to be rolled) By designing the hole types of the third hole type K3 and the fourth hole type K4 so that the hole type rolls are in contact with each other, the width of the flange is maximized as much as possible while ensuring the material permeability and flange dimension accuracy. Folding shaping is realized, and it becomes possible to roll-shape an H-shaped rough shape material for producing an H-shaped steel product having a larger flange width than before.

  The present inventors have further studied a method for setting a specific hole width of a hole mold (fourth hole mold K4 in the present embodiment) that performs final folding modeling when the material slab thickness is 300 mm. Went. FIG. 9 shows the predicted value of the flange width after bending modeling, with the wedge angle (θ3 in the present embodiment) of the folding hole mold (for example, the fourth hole mold K4 in the present embodiment) as the horizontal axis. 6 is a graph obtained by evaluating the rolling stability under each condition with the vertical axis being the difference from the hole width setting value of the bent hole mold designed in this embodiment (for example, the fourth hole mold K4 in the present embodiment). That is, FIG. 9 is data showing evaluation of rolling stability (material passing characteristics) according to the bending angle per one hole type of the bent hole mold.

As shown in FIG. 9, when the wedge angle of the folding hole mold is a predetermined angle, the predicted flange width value after the bending modeling, and the hole width setting value of the actually designed folding hole mold, If the difference is equal to or greater than a predetermined value, rolling stability (♦ in the graph) is achieved.
On the other hand, when the wedge angle of the folding hole mold is a predetermined angle, the difference between the predicted flange width value after folding modeling and the hole width setting value of the actually designed folding hole mold is a predetermined value. If it is below, rolling will become unstable (x in the graph).
The reason why the rolling becomes unstable is that the centering action on the material A to be rolled decreases as the wedge angle of the bent hole mold increases. As a specific example of rolling instability, rolling material inductivity is lowered, and rolling failure such as buckling occurs.

That is, the larger the wedge angle of the folding hole mold, the narrower the design of the hole mold width than the predicted value of the flange width after the folding modeling, thereby restraining the material A to be rolled. Is required to be realized. Also, the smaller the wedge angle of the folding hole mold, the better the centering property of the material A to be rolled. Therefore, the design of the hole mold width is not designed to be so small with respect to the predicted flange width value after folding modeling. It can be seen that rolling stability is ensured.
For example, from FIG. 9, when the wedge angle of the folding hole mold is 90 ° or less, the centering property of the material A to be rolled is sufficient, so that the front end (slab end face) of the flange equivalent part in the folding hole mold It can be seen that rolling stability is realized without bringing the inside of the hole mold (hole roll) into contact and restraining the material A to be rolled.

On the other hand, in the present invention, since the purpose is to produce an H-shaped steel product having a larger flange width than the conventional one, it is desirable that the design of the hole width of the bent hole type is set as large as possible. It is clear. Therefore, the condition that the flange width is maximized within the range in which the rolling stability shown in FIG. 9 is realized, that is, the design of the hole width is set as large as possible with respect to the predicted flange width value after bending modeling. It is desirable to do.
From the above, from the viewpoint of designing the hole width of the bent hole mold under the condition satisfying the following expression (3), the flange width value should be as large as possible and the rolling stability should be ensured. desirable.
Predicted bending hole flange width−hole flange width = c × θ−d (3)
Here, c is the slope of the graph shown in FIG. 9, d is the intercept of the graph shown in FIG. 9, and is a predetermined constant. Further, θ is a wedge angle of a bent hole type which is a design target of the hole type width.

  As described above, from the relationship between the bending angle (Δθ) and the flange width expansion rate shown in FIG. 7, the flange width value of the material to be rolled after bending modeling is predicted, and the predicted flange width value is obtained. Based on this, the hole width is calculated by the method for designing the hole width of the bent hole type described above with reference to FIG. 9 so that the rolling stability is ensured and the flange width is as large as possible. By using the folding hole mold designed to the hole mold width calculated in this way as the final hole mold at the time of bending modeling (fourth hole mold K4 in the present embodiment), the rolling stability is ensured, and It is possible to roll shape a H-shaped rough shape material for manufacturing an H-shaped steel product having a flange width as large as possible and having a flange width larger than that in the past.

  As mentioned above, although an example of embodiment of this invention was demonstrated, this invention is not limited to the form of illustration. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

For example, in the said embodiment, although demonstrated as what shape | molds the to-be-rolled material A by engraving four hole types, the 1st hole type K1-the 4th hole type K4, in order to implement a rough rolling process However, the number of hole types is not limited to this. That is, the number of hole molds engraved in the sizing mill 3 or the rough rolling mill 4 can be arbitrarily changed, and is appropriately changed to such an extent that the rough rolling process can be suitably performed.
In addition, regarding the case where the hole mold for performing folding modeling is multi-staged, as described with reference to FIG. 8 in the above embodiment, the influence on the flange width by the number of stages of folding modeling is extremely small. The technology of the present invention can be applied regardless of the number of hole-type stages for performing bending modeling.

  Moreover, although the slab was illustrated and demonstrated as a raw material (rolled material A) at the time of manufacturing H-section steel, naturally this invention is applicable also to the other raw material of a similar shape. That is, for example, the present invention can also be applied to the case where an H-shaped steel is manufactured by shaping a beam blank material.

  The present invention can be applied to a manufacturing method for manufacturing H-section steel using, for example, 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 12 ... Flange corresponding part 13 ... H-shaped rough shape material 14 ... Intermediate material 16 ... H-shaped steel product 20 ... Upper hole type roll (first hole type)
21 ... Preliminary hole type roll (first hole type)
25, 26 ... Projection (first hole type)
28, 29 ... Interrupt (first hole type)
30 ... Upper hole type roll (second hole type)
31 ... Pilot hole roll (second hole type)
35, 36... Projection (second hole type)
38, 39 ... Interrupt (second hole type)
40 ... Upper hole type roll (third hole type)
41 ... pilot hole type roll (third hole type)
45, 46 ... Projection (third hole type)
48, 49 ... Interrupt (3rd hole type)
50 ... Upper hole type roll (4th hole type)
51. Pre-hole type roll (fourth hole type)
55, 56 ... Projection (fourth hole type)
58, 59 ... Interrupt (4th hole type)
80 ... Flange K1 ... 1st hole type K2 ... 2nd hole type K3 ... 3rd hole type K4 ... 4th hole type T ... Production line A ... Rolled material

Claims (3)

A method for producing an H-section steel comprising a rough rolling process, an intermediate rolling process, and a finish rolling process,
A rolling mill that performs the rough rolling process on a rectangular cross-section material is engraved with a plurality of four or more perforations that form the material to be rolled,
In the plurality of hole molds, one or a plurality of passes of the material to be rolled are formed,
Among the plurality of hole molds, the first hole mold and the second hole mold are formed with protrusions that vertically interrupt the width direction of the material to be rolled,
After the second hole mold among the plurality of hole molds, the rolling is performed in a state where the end surface of the material to be rolled and the peripheral surface of the hole mold are in contact with each other in modeling of at least one pass.
Of the plurality of hole molds, after the third hole mold, a bending molding process is performed in which the divided parts formed by the interruption are sequentially bent,
When the thickness of the rectangular cross-section material is 290 mm or more and 310 mm or less, the ratio of the rolled material flange width after shaping in the second hole mold and the rolled material flange width in the final shape of the bending shaping process A certain flange width expansion rate is defined by the following formula | equation (2), The manufacturing method of H-section steel characterized by the above-mentioned.
Flange width expansion ratio = a × Δθ + b (2)
However, a and b are predetermined constants, and Δθ is a bending angle in the bending modeling step. The plurality of hole molds are four hole molds of a first hole mold to a fourth hole mold for forming a material to be rolled,
Among the plurality of hole molds, the third hole mold and the fourth hole mold are formed with a protrusion that bends the divided part by pressing against the divided part,
The tip angle of the protrusions formed in the first hole mold and the second hole mold is 25 ° or more and 40 ° or less,
The flange width expansion rate is determined based on the formula (2) when the bending angle Δθ in the bending modeling process in the third hole mold and / or the fourth hole mold is in the range of 30 ° to 150 °. The manufacturing method of the H-section steel of Claim 1 characterized by these. Based on the flange width expansion rate determined by the equation (2), predict the flange width value of the material to be rolled after the folding shaping process,
Designing the hole flange width of the fourth hole mold so that the relationship between the predicted flange width of the material to be rolled and the fourth hole mold performing the bending shaping process satisfies the following expression (3): The method for producing an H-section steel according to claim 2, wherein the method is characterized in that:
Predicted bending hole flange width−hole flange width = c × θ−d (3)
However, c and d are predetermined constants, and θ is the tip angle of the protrusion formed in the fourth hole mold.

Images