JP6668963B2 - Method of manufacturing H-section steel - Google Patents

Description

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

  In the case of manufacturing an H-section steel, materials such as slabs and blooms extracted from a heating furnace are formed into a coarse 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 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, the H-shaped 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 was made in the slab end face in the first die in the rough rolling process. After that, a technique is known in which the interruption is expanded in the second and subsequent cavities, or the edging rolling is performed by increasing the interruption depth, and the interruption of the slab end face is eliminated in the subsequent cavities (for example, Patent Document 1).

  In such an H-section steel manufacturing technique, it is known that a flattening pass called a so-called “gearing” is introduced at the time of flat forming rolling for reducing the thickness of the web, as described in Patent Document 2, for example. Have been. This is done in order to suppress the cropping part caused by flat forming rolling and to prevent biting during flat forming rolling by adopting a pass schedule that alternately repeats edging rolling and flat forming rolling in flat forming rolling. Is what is done.

JP-A-7-88501 JP-A-1-186201

  In recent years, with the enlargement of structures and the like, production 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 wider 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 in which an end face of a material such as a slab (an end face of a slab) is interrupted, the end face is edged, and rough rolling is performed 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. In addition, it is conceivable to increase the edging amount by increasing the size of the material itself such as slabs.However, there is a limit to the equipment scale and rolling reduction of the rough rolling mill, so that a sufficient product flange cannot be widened. There are circumstances.

  Further, when performing a shape shaping pass called so-called “earing” as disclosed in the above-mentioned Patent Document 2, a die for performing edging rolling (an edging die) and a die for performing flat forming rolling are provided. (A flat molding hole type) is repeatedly used. At that time, when the material to be rolled once subjected to flat forming rolling is returned to the edging hole again, the flange width of the material to be rolled is short, and the material to be rolled by the edging hole is sufficiently restrained. And there is a risk that the timber will be unstable. Also, in flat forming rolling, since the stretching of the web is extremely large compared to the stretching of the flange, the material to be rolled is likely to bend up and down, and in the subsequent ear rolling, the material to be rolled turns 90 ° or 270 °, Rolling is started from a state in which the material to be rolled before rolling has a large left-right bend, and there is a problem in that the hole-like shape having an extremely low inductivity originally tends to cause troubles in the material passing. In addition, in the shape shaping pass called “ear picking”, since rolling in different hole types (edging hole type and flat-shaped hole type) is repeated, the amount of change in the roll gap of the hole type becomes extremely large, and productivity and There is a concern that efficiency will decline.

  In view of the above circumstances, an object of the present invention is to insert a deep interrupt into the end face of a material such as a slab with a projection having an acute-angled tip in a rough rolling step using a die when manufacturing an H-section steel, By successively bending the formed flange portion, the occurrence of shape defects in the material to be rolled is suppressed, and the rough rolling process is performed without performing the conventional shape shaping pass called ear trimming. It is an object of the present invention to provide a technique for manufacturing an H-section steel capable of improving the quality.

In order to achieve the above object, according to the present invention, there is provided a method for producing an H-section steel including a rough rolling step, an intermediate rolling step, and a finish rolling step, wherein a rolling mill for performing the rough rolling step includes A plurality of five or more molds for rolling and shaping the rolled material are engraved, and one or more passes of the material to be rolled are performed on the plurality of molds, and a first mold and a first mold of the plurality of molds are formed. The two-hole type is provided with a projection which is formed vertically at the width direction of the material to be rolled to form a divided portion at the end of the material to be rolled. After the three-hole type, a projection that abuts on the interruption and sequentially bends the formed divided portion is formed, and the final one of the plurality of die types is a flat-type die. Is a continuous multiple pass using only the flat molding die by reverse rolling. Made by casting and said at flat shaped caliber, the corner portion opposing portion which faces the connecting portion inside the web portion and the flange portion of the material to be rolled, the rolled material has been introduced into the flat shaped grooved web A relief portion is provided as means for reducing the amount of reduction with respect to the inside of the connection portion between the portion and the flange portion, and the shape of the relief portion is introduced into the flat molding die during the multiple pass rolling by the flat molding die. H-shaped, characterized in that, in a state where the center position of the web portion of the material to be rolled and the flat-shaped grooved roll are in contact with each other, the inside of the connection portion between the web portion and the flange portion is not lowered. A method for producing steel is provided.

  As the front mold of the flat molding mold, a box mold for expanding the interruption of the material to be rolled and shaping the outside of the formed divided portion into a substantially flat shape may be further provided.

  The rolling mill for performing the rough rolling step is composed of two or more rolling stands, and among the plurality of dies, the dies except the final dies, and the final dies are engraved on different rolling stands. Is also good.

  In the rolling mill performing the rough rolling step, in addition to the plurality of molds, a widening mold for performing in-web widening rolling of the material to be rolled is further engraved at a later stage of the roll molding with the plurality of molds. The widening die may be engraved on the same rolling stand as the flat molding die.

  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 surface of a material such as a slab by a projection having an acute-angled tip shape, and thus formed. By sequentially bending the flanges, it is possible to suppress the occurrence of shape defects in the material to be rolled, and to carry out the rough rolling process without performing the conventional shape shaping pass called ear trimming, thereby improving rolling efficiency. Can be.

It is a schematic 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 explanatory drawing which compares the shape of the flange part after the edging rolling in the conventional manufacturing method, and the shape of the flange part formed by the 1st to 4th molds based on this Embodiment. It is a schematic sectional drawing which shows the mode of rolling by the flat shaping | molding die of a flange part. It is a schematic enlarged explanatory drawing regarding the corner part opposition part of a flat molding type | mold. It is explanatory drawing regarding the difference of the rolling shape of the stationary part and the non-stationary part at the time of the edging rolling in the manufacturing method of the conventional H-section steel. It is a schematic explanatory drawing of a box hole type.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the 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 thereof may be appropriately illustrated in each drawing using broken lines, oblique lines, and the like.

  As shown in FIG. 1, in a production line T, a material having a rectangular cross section, for example, a slab 11 extracted from a heating furnace 2 (a material to be rolled A) 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. During the intermediate rolling, the edge end of the flange (the flange corresponding portion 12) of the material to be rolled is reduced by the edger rolling machine 9 as necessary. In the usual 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 of 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 finish universal rolling mill 8, and an H-shaped steel product 16 is manufactured.

  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, the configuration and shape of the groove formed in the sizing mill 3 and the rough rolling mill 4 shown in FIG. 1 will be described with reference to the drawings. FIGS. 2 to 6 are schematic explanatory diagrams of the sizing mill 3 that performs 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 rough rolling mill 4 may include five first to fifth molds. The hole shape may be separately engraved. That is, the first die to the fourth die may be engraved over 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, molding in one or a plurality of passes is performed in each of these molds.

  Further, in the present embodiment, a description will be given by exemplifying a case in which five holes are engraved. However, 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 configuration suitable for shaping 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 is rolled. Pressed 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 projection 25 protruding toward the inside of the hole shape is formed. Further, on the peripheral surface of the pilot hole roll 21 (that is, the bottom surface of the first die K1), a projection 26 projecting toward the inside of the die is formed. 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 interrupts 28 and 29 are formed. Here, the tip angle (also referred to as a wedge angle) θ1a of the projections 25 and 26 is desirably, for example, not less than 25 ° and not more than 40 °.

  Here, it is preferable that the die width of the first die K1 is substantially equal to the thickness of the material A to be rolled (that is, the slab thickness). Specifically, by making the width of the groove at the tip of the projections 25 and 26 formed on 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 surfaces) 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 upper and lower ends of the slab divided into four elements (parts) by the interrupts 28 and 29 have first holes. 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 causes the material A to be rolled to elongate in the longitudinal direction, thereby lowering 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 reduction in the projections 25 and 26 when the interruptions 28 and 29 are formed. 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 diagram of the second hole type K2. The second hole type K2 is engraved on an upper hole type roll 30 and a lower hole type 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 protruding 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 such as the projection length are the same for the projection 35 and the projection 36. It is desirable that the tip angles of these projections 35 and 36 are wedge angles θ1b of 25 ° or more and 40 ° or less.

  The wedge angle θ1a of the first hole mold K1 is used to secure the thickness of the front end of the flange-equivalent portion, to enhance the inductivity, and to 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, 36 is higher than the height h1 of the projections 25, 26 of the first hole type K1, and h2> h1. In addition, it is preferable from the viewpoint 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 roll 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.
Further, 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. The four locations shown are all 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, the first mold K1 is used in the second mold K2. The shaping is performed so that the interruptions 28 and 29 formed in are further deepened, and interruptions 38 and 39 are formed. The width of the flange piece at the end of the flange forming process in the rough rolling process is determined based on the dimensions of the interruptions 38 and 39 formed here.

  Further, the molding with the second die K2 is performed by multiple passes. In the multi-pass modeling, the upper and lower ends (slab end surfaces) of the material A to be rolled in the final pass and the die upper surface 30a opposed thereto. , 30b and the hole-shaped bottom surfaces 31a, 31b are formed. This is because if the upper and lower ends of the material A to be rolled and the inside of the groove are not in contact with each other in all the passes of the second groove K2, the flange equivalent portion (the portion corresponding to the flange portion 80 described later) is asymmetric. This is because there is a possibility that a shape defect such as molding 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, on 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 projection length are the same for the projection 45 and the projection 46.

The tip angle θ2 of the projections 45 and 46 is wider than the angle θ1b, and the depth h3 of penetration of the projections 45 and 46 into the workpiece A is the depth of penetration of the projections 35 and 36. Is shorter than h2 (that is, h3 <h2). This 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. The four locations shown are all 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 on the upper and lower ends (slab end faces) of the material A to be rolled in the second die K2. The interrupts 38, 39 are interrupted 48, 49 by the projections 45, 46 being 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) is θ2. In other words, in the second hollow mold K2, modeling 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 faces) of the material A to be rolled and the inside of the die (the first die). This is performed in a state where the upper surface and the lower surface of the three-hole type K3 are in contact with each other. When the upper and lower ends (slab end faces) of the material A to be rolled are in contact with the inside of the die, it is preferable that the ends be lightly reduced.

  FIG. 5 is a schematic explanatory view of the fourth hole die 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, on 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 protruding 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 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, interrupts 48 and 49 formed in the third hole type K3 at the upper and lower ends (slab end faces) of the material A to be rolled with respect to the material A after passing through the third hole type K3. , And the projections 55 and 56 are pressed and spread, and interrupts 58 and 59 are formed. 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, molding 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.

  The shaping with the fourth die K4 shown in FIG. 5 is performed by at least one or more passes, and at least one or more of these passes includes the upper and lower ends (slab end faces) of the material A to be rolled and the inside of the die (the fourth die). This is performed in a state where the upper surface and the lower surface of the mold K4 are in contact with each other. When the upper and lower ends (slab end faces) of the material A to be rolled are in contact with the inside of the die, it is preferable that the ends be lightly reduced.

  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 rolled material A formed up to the fourth die K4 is rotated by 90 ° or 270 °, and the rolled material A is 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 dimensional adjustment of the flange width is performed by lowering the web portion 82, which is a connecting portion connecting the two flange portions 80, and lowering the flange tip portion of the flange portion 80. In this way, 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 by reducing the web part 82, it is also called a web thickness reduction type | mold or a flat molding type | mold.

  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 shaped material 13 by widening the flange width as compared with the conventional rough rolling method of constantly rolling down the end face of the slab, and as a result, the final product having a large flange width ( H-section steel).

  Here, in the method of manufacturing the H-section steel according to the present embodiment, the shape of the flange portion 80 of the material A to be rolled formed by the above-described first to fourth hole types K1 to K4 is the same as that of the conventional manufacturing method. The shape is close to the shape of the product flange as compared to the shape of the flange portion before the flat-hole molding in the method. This is due to the adoption of a shaping technique that bends a divided part (flange part 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. FIG. 7 is an explanatory diagram for comparing the shape of the flange portion after the edging rolling in the conventional manufacturing method with the shape of the flange portion 80 formed by the above-described first die K1 to fourth die K4. . FIG. 7 also shows that the shape of the flange formed by the method of manufacturing an H-section steel according to the present embodiment is a shape close to the shape of the product flange.

  As shown in FIG. 7, the shape of the flange portion after edging rolling is greatly different between the conventional manufacturing method and the method according to the present embodiment. According to the study of the present inventors, due to such a difference in the shape of the flange portion, the deformation of the material A to be rolled is reduced in the subsequent step of the rolling molding with the flat molding die (fifth die K5). It turns out there is a difference.

  FIG. 8 is a schematic cross-sectional view showing a state in which the flange portion is rolled by the flat molding die, and FIG. 8A shows a state in which the flange portion is rolled by the flat molding die in the conventional manufacturing method; (b) shows a state in which the flange portion formed by the manufacturing method according to the present embodiment is rolled by the flat molding die. In addition, in FIG. 8, for simplification of description, a quarter portion of the material A to be rolled is shown in an enlarged manner.

As shown in FIG. 7, since the conventional manufacturing method is a rolling method using the width expansion of the flange portion due to the reduction, the vertical reduction of the material to be rolled easily penetrates, and the corner portion easily increases in thickness. There are features. Here, the corner portion is the inside of the connection point between the web portion and the flange portion in the material to be rolled, which is indicated by a broken line in FIG. As described above, when the roll molding by the flat molding die is performed in a state where the corner portion is thickened, the corner portion in the thickened state is pressed down, and the metal is easily spread outward. . As a result, a shape defect called “biting out” is likely to occur at a biting out position indicated by a solid line in FIG. 8A.
For the material to be rolled in which "biting out" has occurred, for example, as described in Patent Literature 2, a die for performing edging rolling (an edging die) and a die for performing flat forming rolling (Flat molding hole type) and a shape shaping pass called so-called “ear picking” in which molding is repeatedly performed by using the “shape molding die”, thereby normalizing shape defects.

  On the other hand, as shown in FIG. 7, in the manufacturing method according to the present embodiment, the penetration of the material to be rolled in the vertical direction is small, and the corner portion is not increased by the rolling molding. For this reason, when rolling shaping is performed by the flat shaping die, the amount of spread of the metal to the outside is small, and the above-described shape defect such as so-called “biting out” is unlikely to occur.

  As described with reference to FIGS. 7 and 8, according to the method of manufacturing the H-section steel according to the present embodiment, it is possible to suppress a shape defect when performing the rolling shaping by the flat shaping die. After the edging rolling, the rough rolling step can be completed by multiple-pass rolling using only the flat molding die (the fifth die K5 in the present embodiment). That is, the rough rolling step can be completed without introducing the shape shaping pass referred to as the so-called “ear picking” described above.

  In addition, since it is not necessary to introduce a shape shaping pass called so-called “ear picking”, a final shaping die having the edging hole (the fourth hole K4 according to the present embodiment) and a flat-shaped shaping die (the present embodiment). The fifth die K5) according to the embodiment does not need to be engraved on the same die roll (that is, the same rolling stand), and the die die design flexibility is improved. In the actual operation, for example, there are cases where the operation is performed by using one of the edging hole type and the flat molding type with the automatic operation and the other as the manual operation. In such a case, an efficient operation can be realized by using a separate stand for the rolling stand for engraving the edging mold and the flat molding mold.

  Further, for example, in the production of particularly large H-section steel products having a web height of 900 mm or more, further suppression of shape defects may be required. That is, as described above, in the present embodiment, it has been described that the corners of the material to be rolled are not increased by the rolling molding, but particularly when a large H-shaped steel product is manufactured. Since the ratio of the web portion in the cross section of the material to be rolled is large, the absolute value of the web height expansion amount due to the web reduction is large, and only the technology according to the above-described embodiment has a sufficient shape defect. It is considered that suppression may not be realized in some cases.

  Therefore, the present inventors, in order to further suppress the shape defect that occurs in the material A to be rolled, in the flat molding die (see FIG. 6) corresponding to the fifth die K5 in the present embodiment, We proposed to improve the shape of the hole-shaped corner opposing part in a suitable manner, and examined its specific shape.

  The fifth hole type K5 according to the present embodiment is a so-called “web thinned hole type” or “flat-shaped hole type” in which the web portion 82 is pressed down to reduce the thickness, and a conventional H-shaped. It has a known hole shape that has been used in steel production. The shape of the corner-facing portion in the flat molding die is a so-called double R, which is formed by continuously connecting curved portions having two types of curvatures, large or small, or a tapered straight portion and a curved portion. It is common to have any one of the following types of curved shape portions: a continuous configuration. In addition, the shape of the flat molding die shown in FIG. 8 is a so-called double R, which is formed by continuously connecting curved portions having two types of curvatures, large and small.

  Regarding the flat molding die (fifth hole die K5) configured as described above, the fifth hole is formed in order to prevent the metal from spreading outward due to the reduction of the corner portion as described above with reference to FIG. In the mold of the mold K5 (flat molding mold), a relief portion is provided at a location opposed to the corner, and in the first pass rolling molding with the fifth mold K5, the shape is formed at the corner of the material A to be rolled. On the other hand, it is conceivable to adopt a shape that satisfies the condition that the roll hardly comes into contact.

Hereinafter, a specific shape of the relief portion will be described below with reference to FIG. 9. FIG. 9 is a schematic enlarged explanatory view showing a corner facing portion of a flat molding die (the fifth die K5 in the present embodiment), and FIG. (B) is an explanatory view showing a preferred shape of the escape portion.
As shown in FIG. 9A, the corner portion C of the material A to be rolled is a portion shown by a broken line in the figure, which is off the intersection of the extension of the inner surface of the web portion 82 and the extension of the inner surface of the flange portion 80. Is defined as Then, the groove height design of the fifth hole die K5 according to the present embodiment is made such that the reduction amount of the corner portion C is reduced at the reduction start position of the web portion 82, so that the web height during flat forming rolling is reduced. The spread amount can be suppressed, and the shape defect can be suppressed.

That is, as shown in FIG. 9A, it is desirable to design a hole shape in which a relief portion 90 (a broken line portion in the figure) is formed as a reduction amount reduction means for reducing the reduction amount with respect to the corner portion C. With such a groove design, as described above, the amount of web height expansion during flat forming rolling can be suppressed, and shape defects can be suppressed.
Further, it is preferable that the detailed shape of the relief portion 90 as the reduction amount reduction means is determined as follows. That is, as shown in FIG. 9 (b), in a state where the roll-shaped roll and the web portion 82 are in contact with no gap at the center position of the web portion 82, the corner portion C is formed so as not to be pressed down. Is desirable.
The roll molding with the fifth die K5 is usually performed in a plurality of passes, and if the roll does not contact the corner C in all the passes of the plurality of passes, there is a problem that the roll molding of the corner C is not performed at all. In the rolling molding after the first pass, a hole-shaped design may be adopted in which the roll suitably contacts the corner portion C. That is, it is desirable that the shape of the relief portion 90 be determined based on the position where the hole-shaped roll and the web portion 82 are in contact with no gap at the center position of the web portion 82. By forming the relief portion 90 in such a shape, the amount of reduction in the corner portion C can be reduced, so that the spread of the web height during flat forming rolling can be suppressed.

  According to the manufacturing method according to the embodiment of the present invention described above, after the edging rolling, the rough rolling step is performed by the multiple-pass rolling using only the flat molding die (the fifth die K5 in the present embodiment). By doing so, the rough rolling step can be completed without causing a so-called "begging" shape defect. Further, in particular, in the case of manufacturing an H-section steel product having a web height of 900 mm or more, by using a flat-shaped die having a “relief portion” as shown in FIG. Is normalized.

By the way, it is known that in a rough rolling process in the production of an H-shaped steel product, the rolling shape differs between a steady portion and an unsteady portion (end portion) in the longitudinal direction of the material A to be rolled.
FIGS. 10A and 10B are diagrams illustrating a difference in rolling shape between a steady portion and an unsteady portion during edging rolling in a conventional method for manufacturing an H-section steel. FIG. 10A illustrates a steady portion, and FIG. Is shown. As shown in FIG. 10A, the thickness tw of the web portion in the steady portion of the material to be rolled is substantially the same as the thickness of the material slab. Further, as shown in FIG. 10B, the maximum thickness tw0 of the web portion in the unsteady portion of the material to be rolled increases and becomes larger than the thickness of the material slab.
This is due to the fact that the edging rolling in the conventional manufacturing method is a process utilizing the width expansion by the edging rolling, so that the reduction reaches the web portion of the material to be rolled. In particular, in the unsteady portion corresponding to the longitudinal end portion of the material to be rolled, the metal flow in the longitudinal direction is easily generated during the rolling molding, so that the thickness of the central portion of the web portion increases and becomes larger than the material slab thickness.
When the unsteady portion of the material to be rolled, in which the thickness of the central portion of the web is greater than the thickness of the material slab as shown in FIG. 10B, is introduced into the flat molding die, the rolling in the flat molding die is performed. In the modeling pass (especially, the initial pass), the spread amount of the metal to the hole-shaped side wall is increased, and there is a possibility that a shape defect such as so-called “biting out” may occur.

On the other hand, in the edging rolling in the method of manufacturing the H-section steel according to the present embodiment, as described with reference to FIGS. 2 to 6, interruptions are made at the upper and lower ends (slab end faces) of the material A to be rolled. By shaping each part which is divided into right and left by these interruptions to form the flange part 80, the upper and lower end surfaces of the material to be rolled A (slab) edging without being pressed down substantially in the vertical direction. Rolling. Therefore, the dimensional change in the longitudinal direction of the material to be rolled is small, and the deformation of the web portion is extremely small. That is, the thickness of the web portion hardly changes between the steady portion and the non-steady portion of the material A to be rolled, and the material is introduced into the flat mold cavity with a thickness close to the thickness of the material slab.
From such a viewpoint, in the manufacturing method according to the present embodiment, in particular, the unsteady portion of the material A to be rolled is also subjected to the rough rolling process by a plurality of pass rolling using only the flat molding die after the edging rolling. Thus, the rough rolling step can be completed without causing a shape defect referred to as so-called "biting out". As a result, productivity and yield can be improved.

  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 concept described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

  In the above-described embodiment, a technique of shaping the material A to be rolled using the four molds of the first mold K1 to the fourth mold K4, and then performing flat forming rolling 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. That is, the configuration of the groove shown in the above embodiment is an example, and the number of grooves formed in the sizing mill 3 and 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.

  For example, between the fourth die K4 and the fifth die K5, the interrupts 58 and 59 formed on the material A to be rolled after the fourth die K4 pass through are spread out, and the divided portions (the later) It is also possible to provide a groove for forming the flange portion 80) so as to be bent further outward so as to have a substantially flat surface in the final pass. That is, it is also possible to carry out modeling such that the deepest part angle θ3 of the interrupts 58 and 59 formed by the fourth hole die K4 becomes substantially 180 °.

  FIG. 11 is a schematic explanatory view of a box mold 100 that can be further provided between the fourth mold K4 and the fifth mold K5. The box die 100 includes a pair of horizontal rolls, an upper roll 110 and a lower roll 111. The upper hole type roll 110 and the lower hole type roll 111 have a roll peripheral surface that is horizontal to the material A to be rolled. In this box hole die 100, the pressure is reduced to such an extent that the interrupts 58 and 59 formed in the fourth hole die K4 described in the above embodiment can be erased. Specifically, the depth of the interrupts 58 and 59 formed in the fifth hole mold K5 (that is, the depth h4 at which the protrusions 55 and 56 penetrate into the material A to be rolled) is about 50 mm to one pass. It is preferable to apply a reduction of about 60 mm.

  In the box mold 100 shown in FIG. 11, the formed interrupts 58 and 59 are pushed and spread on the material A to be rolled after the fourth mold K4 has passed through, and the divided portion (flange portion 80) is further bent outward. Then, in the final pass, modeling is performed so as to have a substantially flat surface. That is, modeling is performed such that the deepest part angle θ3 of the interrupts 58 and 59 formed by the fourth hole die K4 becomes substantially 180 ° (substantially flat) by the forming with the box die 100.

  By further providing such a box mold 100 shown in FIG. 11 between the fourth mold K4 and the fifth mold K5, the flat molding by the latter flat mold (ie, the fifth mold K5) is performed. At the time of rolling, the contact area between the groove side wall and the material A to be rolled can be increased. In particular, when manufacturing a large H-section steel product having a product height of 900 mm or more, the width of the product due to the web reduction becomes extremely large because the method in the web of the product is large relative to the slab thickness of the material. The shape defect (see FIG. 8) such as the so-called "biting out" described in (1) becomes remarkable. In such a case, if the box mold 100 is provided between the fourth mold K4 and the fifth mold K5, it is possible to further suppress the occurrence of shape defects.

Further, in the above embodiment, since it is not necessary to introduce a shape shaping pass which is called “ear picking”, the final shaping type of the edging hole type (the fourth hole type K4 according to the above embodiment) and the flat molding It is not necessary to engrave the mold (the fifth mold K5 according to the above-described embodiment) on the same mold roll (that is, the same rolling stand), and the mold design freedom is improved. explained.
On the other hand, particularly in the production of a large H-shaped steel product, there is a case where rolling shaping is carried out by using in-web widening rolling. In-web widening rolling is a method generally performed conventionally in the manufacture of H-section steel products. Usually, a new rolling stand is provided, or the number of dies is secured by two heat rolling, and the web is rolled. It is known to perform internal widening rolling.

In such a situation, as described above, in the present invention, since it is not necessary to engrave the final shaping die and the flat shaping die in the same rolling stand, the degree of freedom in designing the die is improved. Accordingly, in the rolling mill (or row of rolling mills) that performs the rough rolling process, in the same equipment space as before, a new rolling stand is not provided, and a measure such as performing two-heat rolling is performed without taking measures to increase the width of the web inside the web. A wide hole die for rolling can be engraved to increase the efficiency of manufacturing large H-section steel products.
For example, in the rolling line T (see FIG. 1) according to the above-described embodiment, the sizing mill 3 and the rough rolling mill 4 are provided as rolling mill rows for performing the rough rolling process. It is possible to engrave the molds (K1 to K4), and to engrave the flat-molded mold (K5) and, if necessary, the widening mold for performing the in-web widening rolling in the rough rolling mill 4.

  In addition, although the slab was illustrated and illustrated as a raw material (rolled material A) at the time of manufacturing an H-section steel, it can be applied to other rectangular cross-sectional raw materials. That is, the technology of the present invention can be applied to, for example, manufacturing an H-section steel by shaping a beam blank material.

As an example of the present invention, a pass schedule of flat shaping rolling in a conventional method of manufacturing an H-beam (comparative example) and a pass schedule of flat shaping hole type in a method of manufacturing an H-beam according to the present invention (example) And each were formulated, and both were compared. In addition, the flat shaping rolling in the conventional method for manufacturing an H-section steel refers to a method of performing a shape shaping pass referred to as a so-called “ear picking” as described in Patent Document 2, for example.
Here, in the examples and comparative examples, a pass schedule was formulated by taking, as an example, a case where flat forming rolling was performed on a material to be rolled having a web thickness of 300 mm, and flat forming rolling was performed up to a web thickness of 90 mm.
In the present example, a slab having a width of 1500 mm and a thickness of 300 mm is used as a raw material to exemplify a flat molding die for manufacturing an H-section steel product having a web height of 1000 mm and a flange width of 400 mm, and a hole used in flat molding rolling. The shape of the corner-facing portion of the mold was a so-called double R shape, and was formed by continuously connecting curves having curvatures of R1000 and R70.

  Table 1 is a table showing a pass schedule of flat forming rolling according to the comparative example, and Table 2 is a table showing a pass schedule of flat forming rolling according to the example. Table 3 is a table comparing the number of passes and the rolling time between the comparative example and the example. In Tables 1 and 2, G4 indicates rolling in the flat molding die, and G3 indicates an edging die which is a stage preceding the flat molding die (G4).

As shown in Table 1, in the comparative example, in the third pass, the fourth pass, the seventh pass, and the eighth pass, the material to be rolled was returned from the flat molding die to the edging die, and a shape shaping pass was performed. (So-called "ears"). This is to suppress the occurrence of a shape defect called “biting out” described with reference to FIGS. 7 and 8 in the above embodiment.
On the other hand, as shown in Table 2, in the embodiment, a shape shaping pass called so-called “ear picking” is not performed, and the pass schedule is designed using only the flat molding hole type (G4).
That is, as shown in Table 3, in the pass schedule according to the example, the number of passes is reduced from 17 times to 13 times as compared with the pass schedule according to the comparative example. In addition, the rolling time when the same flat forming rolling is performed is also reduced, and it can be seen that the efficiency of the flat forming rolling is improved. In particular, in the pass schedule according to the embodiment, a roll setup time for performing a shape shaping pass called “ear picking” is not required, so that a significant reduction in rolling time is realized.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a manufacturing method for manufacturing an H-section steel using a slab or the like 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 ... Finish universal rolling mill 9 ... Edger rolling mill 11 ... Slab 13 ... H-shaped rough shaped material 14 ... Intermediate material 16 ... H-section 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 ... Upper 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)
Reference numeral 90: relief portion 100: box hole type 110 ... upper hole type roll (of box hole type) 111 ... lower hole type roll (of box hole type) K1: first hole type K2 ... second hole type K3 ... third hole Mold K4: Fourth hole type K5: Fifth hole type (flat molding hole type)
T: Production line A: Rolled material

Claims (4)

A method for producing an H-section steel comprising a rough rolling step, an intermediate rolling step, and a finish rolling step,
In the rolling mill performing the rough rolling step, five or more molds for rolling and shaping the material to be rolled are engraved,
In the plurality of molds, one or more passes of the material to be rolled are formed,
In the first and second molds of the plurality of molds, a projection is formed to form a divided portion at an end of the material to be rolled by vertically interrupting the width direction of the material to be rolled,
Of the plurality of molds, the third mold and the subsequent molds other than the final mold are formed with a projection that abuts on the interruption and sequentially bends the formed divided portion,
The final mold of the plurality of molds is a flat mold mold,
Rolling molding in the flat molding die is performed by continuous multiple pass rolling using only the flat molding die by reverse rolling ,
In the flat molding die, at the corner portion facing the inside of the connection portion between the web portion and the flange portion in the material to be rolled, the web portion and the flange portion of the material to be rolled introduced into the flat molding die are A relief portion as means for reducing the amount of reduction with respect to the inside of the connection point is provided,
The shape of the relief portion, during the multiple pass rolling by the flat molding die, in the state where the web portion center position of the material to be rolled introduced into the flat molding die, the flat molding die roll is in contact. A method for manufacturing an H-section steel , wherein the inside of a connection portion between the web portion and the flange portion is designed not to be lowered . A box die which spreads out the interruption of the material to be rolled and forms the outside of the formed divided part into a substantially flat shape is further provided as a front die of the flat molding die. 2. The method for producing an H-section steel according to item 1. The rolling mill for performing the rough rolling step includes two or more rolling stands, and among the plurality of dies, the dies except for the last dies, and the final dies are engraved on different rolling stands. The method for producing an H-section steel according to claim 1 or 2, wherein: In the rolling mill performing the rough rolling step, in addition to the plurality of molds, a widening mold for performing in-web widening rolling of the material to be rolled is further engraved at a later stage of the roll molding with the plurality of molds. The method for manufacturing an H-section steel according to claim 3, wherein the widened die is engraved on the same rolling stand as the flat molding die.