JPH07178402A - Production of shape steel for steel-made continuous wall - Google Patents

Abstract

PURPOSE:To economically produce a shape steel for steel-made continuous wall having good rolled shape and quality and a horizontally asymmetric circu lar joints by setting a pass-schedule in a rough rolling process so as to satisfy a specific condition. CONSTITUTION:In the rough rolling process producing a rough rolled stock 21 having a horizontally asymmetric dog bone shape through a break-down mill BD, the asymmetricity of the rough rolled stock is increased successively to prevent the development of large warp. The pass schedule is specified and the ratio L1/L2 of L1 elongation rate of the short side of a flange per one pass to L2 elongation rate of the long side of the flange per one pass is made to be <=1.1 to suppress the warp. Succeedingly, the rough rolled stock is formed to almost a horizontally asymmetric H-beam through universal mills U1, U2 and edgers E1, E2 as the same way as the production of the approximately H-beam. Further, the flange parts are bent as an arc having the diameter larger than the product shape through a finishing mill F in a forming process, and formed to the circular joints to make the aimed product shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a steel wall section steel used as a member for a deep-sea retaining wall or the like, and particularly to a steel wall section steel having a left-right asymmetric circular joint. The present invention relates to a manufacturing method by rolling.

[0002]

2. Description of the Related Art A steel connecting wall is a steel underground connecting member made in a factory and built into the ground to form an underground connecting wall, which is thinner than the conventional reinforced concrete underground wall. -It is possible to easily reduce the construction site space and save labor. In addition, it has excellent characteristics such as good installation accuracy and water-stopping property as compared with normal H-section steel installation. As the steel section wall for connecting walls, a straight section steel having joints at both ends is generally used. The so-called caliber rolling method shown in FIG. 7 is generally widely used as a method for producing a straight section steel having such a joint.

In FIG. 7, the rough shaped steel pieces that have passed through the hole forming B in the roughing process are sequentially processed in the first pass Kal. 10th-10th pass Ka
l. It becomes a product through each step of 1. In such a rolling method, the depth of the roll die is large, and especially in the closed die, the amount of roll refurbishment is large due to the wear of the die, the roll unit is high, and the roll cooling water and Rolling oil is hard to spread to each part, so roll surface roughening, heat cracks, hole type local wear, cracks in mating joints on both edges of the product, etc. easily occur, making the product shape unstable and mass production impossible Further, there is a problem that it is relatively difficult to form the double-edged joint portion of the straight shaped steel. In addition, the above method requires a large number of holes, so even if an attempt is made to roll a large shaped steel, there is a problem that a sufficient number of holes cannot be prepared due to restrictions of the roll cylinder length and the number of mills. It was

As a solution to the problem of forming the joint portion in the above-described caliber rolling method using a hole type, a rolling method for steel sheet pile by universal rolling is disclosed in Japanese Patent Publication No. 47-4.
No. 7784. A typical example of this universal rolling is shown in FIG. In this method, a universal rolling method is introduced into the intermediate rolling process to directly apply reduction to the material forming the joint. However, even in this method, the cross-sectional shape of the steel sheet pile to be rolled is vertically asymmetrical with respect to the longitudinal axis of the steel sheet pile. It uses molds and could not completely solve the above problems.

Therefore, as a method for producing a linear steel sheet pile by making the product shape suitable for the universal rolling method and reducing the hole depth in the universal rolling, Japanese Patent Laid-Open No. 55-1913 shown in FIG. There is a technique disclosed in the publication. However, according to the publication, since the shape of the universal rolling roll is an arc shape, the thickness of the web and the joint is limited to a narrow range. In addition, since it is necessary to prepare dedicated rolls in all steps after the rough rolling step, it is not possible to sufficiently improve the roll unit.

[0006] On the other hand, as a conventional technique for making the H-shaped steel manufacturing universal rolling and sharing the roll, there is a method disclosed in, for example, Japanese Patent Application Laid-Open No. 2-200302. As shown in FIG. 10, this method uses a roll similar to a horizontal roll used for rolling H-section steel in a universal mill in an intermediate rolling step, and the roll is shared to improve the roll unit. However, the hard roll uses a flat roll without a taper, and complete sharing with the H-section steel rolling roll has not been achieved. Further, as a method of bending the flange outward, a skew roll mill, which is not commonly used as a shape rolling mill, is used, so it is necessary to introduce new equipment, resulting in an increase in manufacturing cost.

Therefore, as an example of using a preforming mill or the like instead of the skew roll mill, for example, Japanese Patent Laid-Open No. 4-757.
There is a series of methods for manufacturing a straight-section steel typified by Japanese Patent Publication No. The one disclosed in the same publication does not require a large capital investment as in the case of using a skew roll mill, but as shown in FIG. It is the same as that of the -200302 gazette, and the complete sharing with the H-section steel rolling roll is not achieved. The method disclosed in Japanese Patent Laid-Open No. 4-75702 is a technique for rolling a shaped steel having a vertically symmetrical shape, as shown in FIG.

As a method of rolling asymmetrical straight steel bars, for example, there is a technique disclosed in Japanese Patent Laid-Open No. 4-330113. As shown in FIG. 12, the rolling method disclosed in the publication is one in which one end side of the shaped steel is formed in a female shape and the other end side is formed in a male shape, and the fitting mode of the joint is limited to one type. Therefore, there is a drawback that the degree of freedom in construction is limited when the steel connecting wall is constructed.

In contrast to the above-mentioned technique, there is a method for manufacturing an asymmetric linear steel sheet pile disclosed in Japanese Patent Publication No. 55-11921 filed by the present applicant. The method disclosed in the publication includes the primary and secondary intermediate rolling steps by the upper and lower horizontal rolls of the universal mill and the pair of vertical rolls and the upper and lower rolls of the edger mill in the rolling step, respectively. The formation of the web is performed by the upper and lower horizontal rolls of each universal mill, and the formation of both fitting parts is performed by directly applying the reduction by the vertical roll of each universal mill. Then, in order to form the female fitting portion, the angle of the vertical roll on the female fitting portion side of the universal mill is tilted 5 to 20 degrees outward from the vertical direction in the rolling profile in the primary intermediate rolling process, and the secondary intermediate rolling is performed. In the rolling step, the female fitting portion is similarly tilted by 20 to 40 degrees, and in the subsequent finishing rolling step, the female fitting portion is finish-formed by the upper and lower two-stage horizontal roll stands.

Further, as a technique relating to a rough shaping rolling for producing a left-right asymmetric rough shaping material by a break down mill, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 57-68202. In the publication, as shown in FIG. 13, as the hole type, the material is stood and edged,
A plurality of vertically asymmetrical hole dies 41, 42, 43 having an asymmetrical dogbone shape, and a left-right asymmetrical hole die 4 for rolling a dogbone-shaped material to a material for universal rolling.
4 and are used. Then, the plate-shaped slab is rolled in the slab width direction by a rolling roll having upper and lower asymmetrical hole dies 41, 42, 43, whereby intermediate materials having different flange shapes are formed at both end portions in the width direction of the slab. After that, the rolled material is rotated by 90 ° and rolled by a rolling roll having a left-right asymmetric hole die 44 to obtain a predetermined rough steel for asymmetric shape steel.

According to the method disclosed in Japanese Patent Publication No. 55-11921 described above, the method shown in FIG.
It is possible to manufacture a left-right asymmetrical steel section wall steel for wall. Then, this shaped steel is used as box-shaped steel sheet piles 50 and 51 having an H-shaped cross section by welding plates to two webs of shaped steel as shown in FIG. In the shaped steel having the asymmetrical circular joint, the joint on the small diameter side is commonly used for both male and female members, and therefore various connecting modes are possible as shown in FIG.
In the connection mode 52, joints having different left and right diameters are directly fitted, and in the connection modes 53 and 54, the joint portions are connected via H-section steel. As described above, the left-right asymmetrical steel sectional wall steel shown in FIG. 14 can facilitate fine adjustment of the wall length in the construction of the continuous wall by combining with the H-section steel. There is an excellent advantage that the flexibility of construction is high.

[0012]

However, the above-mentioned conventional method for manufacturing a steel section wall for steel wall is mainly intended for a symmetrical or asymmetrical shaped steel having a male joint on one side, and the above-mentioned left-right asymmetric There are few documents that clearly disclose a method for manufacturing a steel section wall steel. Further, even in the method for producing a steel wall section steel having a left-right asymmetric circular joint, the method disclosed in Japanese Unexamined Patent Publication No. 2-200302 can achieve complete sharing with H-section rolling rolls. In addition, as a method of bending the flange outward, an oblique roll mill, which is not generally used as a shape rolling mill, is used, which causes a problem of high manufacturing cost.

Further, according to the method of Japanese Patent Publication No. 55-11921, the left-right asymmetric straight-section steel can be rolled by the same roll as the conventional H-section steel until the first intermediate universal rolling. In the secondary intermediate universal rolling, the angles of the horizontal rolls, vertical rolls and edger rolls are tilted outwardly from the vertical direction by 20 to 40 degrees in the rolling profile, so a dedicated roll is required and the cost increases. Further, there is a problem in that the size of the joint that can be formed is limited because there is a pair of finish forming cavities and molding defects such as waviness occur in the joint when forming a large-diameter thin-walled joint. Further, the publication does not disclose any technique of rolling into a roughly shaped material by using a breakdown mill.

Further, the method of manufacturing a left-right asymmetric rough modeling material using a breakdown mill disclosed in Japanese Patent Laid-Open No. 57-68202 has the following problems. That is, when the slab is edged in a vertically asymmetrical hole shape, a difference occurs in the longitudinal elongation of the upper and lower flange forming portions of the slab due to the asymmetry, and the rolled material 47 is warped as shown in FIG. Then, as shown in FIG. 18, when the edging is performed in a state where the upper hole die 45 is filled and the lower hole die 46 is unfilled as shown in FIG. 18, the widening deformation on the filled side is restrained. Since the elongation in the longitudinal direction becomes large, it occurs particularly remarkably. When the warp is small, it is possible to arrange the narrow-width die on the upper side so that the warp of the rolled material faces downward and press the rolled material against the transport table to correct the warp.

However, when a large warp occurs,
The roll biting becomes unstable and the load on the equipment becomes heavy, causing serious trouble such as damage to the lower strip guide. For this reason, asymmetrical edging rolling is not possible simply by arranging the holes. When edging is repeatedly performed in such a state, warpage is accumulated, and it becomes impossible to continue rolling. In addition, the rolled material with a large warpage due to edging is used in the subsequent die 44 (see FIG. 1).
In (3), the center of the rolled material is rolled in a biased manner with respect to the center of the die, so that the flange portion of the rolled material deviates from the pass line and a defective shape occurs. Although suppressing the warp of the rolled material during edging is very important in the rough rolling process, no effective solution to this has been proposed so far.

The present invention has been made to solve the above problems, and prevents the rolled material from warping in the rough rolling step and utilizes the manufacturing process of the H-section steel rolling as much as possible to obtain a left-right asymmetric circular shape. An object of the present invention is to provide a method for inexpensively manufacturing a steel section wall steel having a joint.

[0017]

SUMMARY OF THE INVENTION A method for manufacturing a steel continuous wall section steel according to the present invention is a break mill having a pair of upper and lower horizontal rolls having an asymmetrical hole shape in a continuously cast steel piece such as a slab. With the rough rolling process of rolling to asymmetrical dog-bone shaped rough shaped material with a left and right, and the same universal mill and the same reduction setting of the flange toe as those used for the H shaped steel manufacturing, the rough shaped material rolled in the step is set. An intermediate rolling step of forming a left-right asymmetric H-shaped steel having a predetermined shape by performing reverse rolling by a plurality of right-left asymmetric edgers, and a left-right asymmetric hole in the flange portion of the H-shaped steel rolled in the step. Circular bending process of bending into an arc shape by a finishing mill having a pair of upper and lower horizontal rolls having a mold, and a flange part bent into an arc shape in the process is almost equal to a target product shape A finish forming step of forming a circular joint which is a product shape by a finish mill having a pair of upper and lower horizontal rolls having an unshaped hole die, and the pass schedule in the rough rolling step is defined by the condition of the following formula (1). It is set to satisfy. L ₁ / L ₂ ≦ 1.1 (1) where L _{1 is the} elongation ratio of the short side of the flange per pass L _{2 is the} elongation ratio of the long side of the flange per pass

[0018]

FIG. 1 is an explanatory view of an embodiment of the present invention, and FIG. 2 is an explanatory view for explaining the arrangement of rolling mills when the method shown in FIG. 1 is carried out. 1 and 2, B
D is a breakdown mill used in a rough rolling process for forming a thin rolled slab as a raw material into a rough rolled material, and R1 and R2 are rough rolled materials formed in the rough rolling step and shaped into a left-right asymmetric H-shaped steel. It is a group of rough rolling mills used in the intermediate rolling process. The rough rolling mill groups R1 and R2 are respectively composed of a rough universal mill U1 and an edger E1, and a rough universal mill U2 and an edger E2. F is a forming mill used in a forming step of forming the flange portion into a circular joint shape. First, the device used in each step will be described.

The break mill BD used in the rough rolling step has a plurality of upper and lower asymmetric hole molds B1 in which the material is erected and edged to form an asymmetric dogbone shape.
~ B3 and at least one left-right asymmetrical hole type Kal., Which rolls a dogbone-shaped material by edging to a rough rolled material for universal rolling. 0. It consists of Here, in order to prevent the occurrence of the above-mentioned warpage, it is necessary to make the vertical asymmetric hole die used for edging into a shape in which the asymmetry of the rolled material is gradually strengthened. Therefore, in this embodiment, the shapes of the upper and lower asymmetric hole shapes B1 to B3 are set as follows. That is, the hole mold B1 has a shape in which the vertical width w is the same and the projecting heights h of the projecting portions 18 and 19 are different in the vertical direction, and the hole mold B2 is different in both the projecting height h and the hole width w in the vertical direction. Further, the hole type B3 has a shape such that the vertical asymmetry is larger than that of the hole type B2.

FIG. 3 is a graph showing the relationship between the reduction amount and the ratio of the flange width and the elongation ratio of the rolled material in the case of edging rolling with the above-mentioned vertically asymmetrical hole dies B1 to B3. The vertical axis of the upper graph in FIG. 3 represents the flange width, and the vertical axis of the lower graph represents the ratio L1 / L2 of the elongation ratio L1 of the upper flange portion and the elongation ratio of the lower flange portion (hereinafter simply referred to as "elongation ratio L2").
Ratio L1 / L2 ”. ) Is shown. Here, the elongation ratio means the length of the rolled material after rolling divided by the length before rolling. The horizontal axis shows the total reduction amount ΔH (mm) in both the upper and lower graphs. Here, the total reduction amount ΔH is
As shown in FIG. 4, the difference between the height H0 of the original rolled material and the height H of the rolled material after rolling is shown. As can be seen from FIG. 3, the upper and lower flange widths increase at a constant rate in any of the hole types (B1, B2, B3) (elongation ratio is almost constant),
There is no filling condition on only one side.

On the other hand, in FIG. 5, the edging corresponding to the machining in the hole dies B1 and B2 is performed in the vertically symmetrical hole type, and the edging corresponding to the machining in the hole die B3 is performed in the vertically asymmetric hole type. By this, it is a graph when the asymmetry of the rolled material is sharply increased by the edging corresponding to the processing in the hole type B3. As can be seen from FIG. 5, in this example, the filling is non-uniform in the upper and lower hole types, so when non-uniform filling occurs, the ratio L1 / L2 of the elongation ratio L1 of the upper flange portion to the elongation ratio L2 of the lower flange portion. Is an extremely large value. As is clear from such comparison, it was confirmed that the shapes of the above-described hole dies B1 to B3 used in this example have an effective effect in preventing warpage of the rolled material in the rough rolling step. In addition, in order to suppress the warpage of the rolled material, it is important to select an appropriate rolling pass schedule together with the shape of the hole shape, which will be described later.

Vertically asymmetrical hole types B1 to B3 for edging
Indicates a small hole width B1U to B3U (the upper hole type is indicated by U, and the lower hole type is indicated by L). Is the same as above), and the hole molds B1L to B3L having a large hole mold width are arranged on the lower side. This is because when asymmetric edging is performed as described above, the extension of the end of the rolled material rolled by the narrow die is larger than the extension of the end of the rolled material rolled by the wider die. Therefore, the rolled material warps, but by arranging the vertical asymmetrical hole molds B1 to B3 as described above, the rolled material warps downward and the rolled material is pressed against the transport table to correct the warp. This is because rolling can be performed without any trouble.

The rolling mills used in the intermediate rolling process are coarse universal mills U1 and U2 and edgers E1 and E2. The coarse universal mill U1 and edger E1 and the universal mill U2 and edger E2 form a pair, respectively. It is arranged as shown in. Here, the horizontal roll 13H of the rough universal mill U1 has a flat surface for rolling the web of the rolled material, the roll side surface for rolling the inner side surface of the flange is inclined outward at an inclination angle θ, and the outer circumference of the roll is longer. Use a shape with a short length. The same applies to the horizontal roll 14H of the coarse universal mill U2. Further, the hard roll 13V of the rough universal mill U1 that rolls the outer surface of the rolled material flange portion projects at the central portion of the outer peripheral surface and inclines from the central portion to the upper and lower ends of the roll. A shape having the same θ as the side surface inclination angle θ is used. The inclination angle θ of these rolls is 3 to 10 degrees as in the case of a normal H-shaped steel rolling roll, and rolling is performed so that the thickness of the flange portion is constant in the width direction. As a result, the universal rolling roll can be shared with an ordinary H-shaped steel rolling roll, and the roll cost can be greatly reduced and the number of rolls held can be reduced. Further, the horizontal rolls incorporated in the edgers E1 and E2 have a hole shape in which the reduction setting of the flange toes is asymmetric so that the target flange width of the asymmetric intermediate rolled material can be obtained.

The forming mill F used in the forming step has a hole having a flat portion having a width substantially equal to the inner width of the web of the intermediate rolled material, and arc-shaped joint forming portions having different diameters on the left and right sides at both ends of the flat portion. Use a mold. In this hole die, the radius of the joint forming portion of the final finish forming hole die 17 is made substantially equal to the target product shape, and the radius of the joint forming portion of the circular bending work hole die 16 of the flange portion preceding this is Use a larger one. With this, the amount of bending work per hole die when forming the flange of the intermediate rolled material into the joint with the hole die is adjusted,
Molding defects such as wavy joints can be prevented.

Next, a method for manufacturing a steel section wall steel having a left and right asymmetric circular joint using the above apparatus will be described. First, in the rough rolling process, using a continuously cast steel slab such as a slab as a rolling material, a left and right asymmetric dogbone-shaped rough shaped material is manufactured with a break down mill BD having a pair of upper and lower horizontal rolls having an asymmetric hole shape. To do. That is, as shown in FIG. 1, with the hole type B1, interrupts of different depths are inserted,
The hole type B2 enlarges the interruption, and the hole type B3 smoothes the interrupted portion. At this time, according to the cavities B1 to B3 used in the present embodiment, edging rolling can be performed so that the asymmetry of the rolled material is gradually strengthened, so that the filling in the upper and lower cavities becomes uniform and a large warp occurs. It can be prevented from occurring.

In order to suppress the warpage of the rolled material,
It is important to choose an appropriate rolling pass schedule as well as the shape of the hole. FIG. 6 shows the hole types B1 to B3 of this embodiment.
4 is a graph showing the relationship between the reduction amount and the ratio of the flange width and the elongation ratio of the rolled material when edging rolling is performed by using the same hole type as that of FIG. 3 and changing the reduction amount per pass from the case of FIG. 3. . Fig. 3 when the reduction is done with an appropriate pass schedule
As shown in Fig. 5, the non-uniform filling does not occur and the ratio of elongation ratio L
While 1 / L2 is almost constant, when the pass schedule is improper, as shown in FIG. 6, the variation of the elongation ratio L1 / L2 is large, and a partly extremely large value. Has become. In this way, the ratio L of the elongation ratio of the upper and lower flanges
If 1 / L2 increases, the warpage of the rolled material increases and the load on the equipment increases. Therefore, the ratio of elongation ratio L1 /
It is necessary to suppress L2 to a certain value or less and minimize the warpage of the rolled material. For that purpose, the ratio of elongation ratio L1 /
It is necessary to find the relationship between L2 and the warpage of the rolled material. Therefore, the relationship between the elongation ratio L1 / L2 and the warp of the rolled material was obtained by an experiment. As a result, when the elongation ratio L1 / L2 exceeds 1.1, the warp cannot be corrected well. , I found that there is a risk of equipment damage.

From this, it was found that the condition under which stable edging can be carried out is to carry out rolling with a pass schedule satisfying the following expression (1). L ₁ / L ₂ ≦ 1.1 (1) where L _{1 is the} elongation ratio of the short side of the flange per pass L _{2 is the} elongation ratio of the long side of the flange per pass

As described above, the edging hole molds B1 to B3
If the ratio of the elongation ratios of the upper and lower flanges of the rolled material is within the range of formula (1) by rolling the steel sheet into a shape with gradually increasing asymmetry and rolling with the appropriate pass schedule described above, warpage is suppressed. At the same time, it is possible to form a rough rolled material that is vertically asymmetric. When the smoothing of the interruption portion is completed, the rolled material is rotated by 90 degrees, and the left and right asymmetrical hole type Kal.
0. Then, it is rolled to a rough rolled material 21 which is a material for universal rolling.

Next, in the intermediate rolling step, the rough rolled material 21 is alternately reverse-rolled by the rough universal mill U1 and the edger E1, and further by the rough universal mill U2 and the edger E2 alternately by reverse rolling. The tip of the flange is pressed down by the hole die of the edger arranged so as to be paired with the universal mill, and molded into a predetermined flange width,
A left-right asymmetric H-shaped steel is formed. At this time, by adjusting the reduction amount of the left and right hard rolls of the rough universal mills U1 and U2 as necessary, it is possible to manufacture a left-right asymmetric H-shaped rolled material having different flange thicknesses. When a substantially H-shaped steel having a predetermined thickness and shape is formed by the intermediate rolling step, the forming step is performed. In the forming process, first, the flange portion is bent into an arc shape having a diameter larger than the target product shape by the circular bending hole die 16, and finally, the target product shape is formed by the finish forming hole die 17. .

Through the above steps, the steel section wall forming steel shown in FIG. 14 can be smoothly manufactured. The web thickness tw of this shaped steel
The size of the joint is adjusted by adjusting the reduction of the horizontal roll of the universal mill, and the thickness tf of the joint is adjusted by adjusting the reduction of the hard roll of the universal mill. Thus, according to the method of the present invention,
By taking advantage of the characteristics of the universal mill, it is possible to manufacture products with various plate thicknesses without changing the rolls.

In the above embodiment, the number of edging hole types is set to 3 pairs, but the number of hole types may be 2 pairs as long as edging rolling satisfying the condition of the above formula (1) is possible. Conversely, if 3 pairs cannot meet the condition, 4
It may be a pair or more.

Further, in the present embodiment, an example was shown in which two sets of intermediate rolling mills were arranged with one set of the rough universal mill and one of the edger as one set, but one set or three sets were provided. Even in the rolling line where the above mills are installed, the intermediate rolled material can be manufactured by the same method.

Further, the example in which the forming mold has two pairs of holes for circular bending and finish forming has been shown. However, if a larger number of holes are used as necessary, a joint having a thinner wall and a larger diameter can be obtained. Can be molded, and the range of product plate thickness that can be manufactured can be expanded. In addition to the finishing mill, if there is a mill having upper and lower horizontal rolls that can be used, the hole die may be divided into two or more mills. Further, if a plurality of pairs of hole dies are formed on one horizontal roll in parallel or superposed, it is possible to increase the number of hole dies with respect to the number of mills.

[0034]

As described above, in the present invention, since the same universal mill as in the H-section steel production is used in the intermediate rolling step, it becomes possible to utilize the H-section rolling process and the universal mill. Since the roll used in the mill can be shared with the conventional H-section steel, it is possible to inexpensively manufacture a steel wall section steel having a left-right asymmetric circular joint.

Further, since the pass schedule in the rough shaping process is set so that the ratio L1 / L2 of the elongation ratio is 1.1 or less, it is possible to shape the asymmetrical rough rolled material while suppressing the warp.

Further, since the forming process for forming the joint portion into a circle is divided into the circular bending process and the finish forming process,
The amount of bending work can be adjusted, forming defects such as corrugation of the joint can be prevented, and a steel shape for steel wall having a right and left asymmetric circular joint with good rolling shape and quality can be manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the invention.

FIG. 2 is an explanatory diagram illustrating the arrangement of rolling mills when the method shown in FIG. 1 is performed.

FIG. 3 is a graph showing the relationship between the reduction amount and the ratio of the flange width and the elongation ratio of the rolled material in this example.

FIG. 4 is an explanatory diagram illustrating a total reduction amount ΔH in the present embodiment.

FIG. 5 is a graph showing the relationship between the reduction amount and the ratio of the flange width and the elongation ratio of the rolled material in the comparative example.

FIG. 6 is a graph showing the relationship between the reduction amount and the ratio of the flange width and the elongation ratio of the rolled material in another comparative example.

FIG. 7 is an explanatory view illustrating a method of manufacturing a shaped steel having a joint by a conventional caliber rolling method.

FIG. 8 is a rolling process diagram of a conventional technique in which a universal rolling method is introduced in an intermediate rolling process.

FIG. 9 is a rolling process diagram of a straight-section steel by conventional universal rolling.

FIG. 10 is a rolling process diagram of a conventional rolling method in which the H-shaped steel is subjected to universal rolling and roll sharing.

FIG. 11 is a rolling process diagram of a conventional method for rolling straight and vertically symmetric linear shaped steel.

FIG. 12 is a rolling process diagram of a conventional method for rolling asymmetrical straight-section steel.

FIG. 13 is an explanatory diagram illustrating a conventional rolling method in a rough rolling step.

FIG. 14 is an outline view of a steel sectional wall steel having a left-right asymmetric circular joint manufactured as an embodiment of the present invention.

FIG. 15 is an explanatory view illustrating an example of a box-shaped steel sheet pile manufactured by assembling the steel wall-formed steel for steel wall manufactured by the present invention.

16 is an explanatory diagram illustrating an example in which the box-shaped steel sheet piles of FIG. 15 are connected to form a continuous wall.

FIG. 17 is an explanatory diagram illustrating the occurrence of warpage of a rolled material in a conventional example.

FIG. 18 is an explanatory diagram illustrating a hole-type unbalanced filling state in a conventional example.

[Explanation of symbols]

BD Breakdown mill R1 Rough 1st rolling mill group R2 Rough 2nd rolling mill group U1, U2 Rough universal mill E1, E2 Edger F Forming mill B1-B3 Edging hole type of breakdown mill Kal. 0-Kal. 10 Hole type 12U, 12L Horizontal roll of edger E1 13HU, 13HL Horizontal roll of universal mill U1 13VU, 13VL Hard roll of universal mill U1 14HU, 14HL Horizontal roll of universal mill U2 14VU, 14VL Hard roll of universal mill U2 15U, 15L Edger E2 horizontal roll 16U, 16L Circular bending hole die 17U, 17L Finish forming hole die 18, 19 Projection 21 Rough rolled material 22, 23, 24, 25 Intermediate rolled material 26 Circular bent rolled material 27 Final product

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuo Higashi 1-2 Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. Main Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A rough rolling step of rolling a continuous cast steel slab such as a slab into a left-right asymmetric dogbone-shaped rough forming material by a breakdown mill having a pair of upper and lower horizontal rolls having an asymmetrical hole shape, and The rolled roughly shaped material is subjected to multiple reverse rolling by a universal mill similar to that used for manufacturing H-section steel and an edger in which the reduction setting of the flange toe is asymmetrical. An intermediate rolling step of forming into steel, and a circular bending step of bending the flange portion of the substantially H-shaped steel rolled in the step into an arc shape by a finishing mill having a pair of upper and lower horizontal rolls having an asymmetric hole shape A finishing mill having a step and a pair of upper and lower horizontal rolls having a hole shape having a shape substantially equal to a target product shape of a flange portion bent in an arc shape in the step. And a finish forming step of forming a circular joint that is a product shape according to the following formula (1).
The method for manufacturing a steel section wall steel wall, characterized in that it is set so as to satisfy the above condition. L ₁ / L ₂ ≦ 1.1 (1) where L _{1 is the} elongation ratio of the short side of the flange per pass L _{2 is the} elongation ratio of the long side of the flange per pass