Method for manufacturing steel sheet piles

Abstract

To suppress change in an angle generated in a joint corresponding part of a rolled material by bending, and change in an opening width, and efficiently manufacture a steel sheet pile having a good joint shape.SOLUTION: A method for manufacturing a steel sheet pile, which subjects a rolled material having at least a flange correspondence part, an arm correspondence part connected to one or both ends of the flange correspondence part and a joint correspondence part connected to the tip of the arm correspondence part to rough rolling, intermediate rolling and finish rolling by hot rolling, and then hot-bends the rolled material, performs pre-molding of changing the shape of the joint correspondence part to a shape different from the product in the pre-stage of bending.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a method for manufacturing steel sheet piles such as hat-shaped steel sheet piles, U-shaped steel sheet piles, and Z-shaped steel sheet piles.

Background Art

[0002] The manufacturing of steel sheet piles having joints at both ends, such as hat-shaped steel sheet piles, U-shaped steel sheet piles, and Z-shaped steel sheet piles, is performed by a pass rolling method as shown in, for example, Patent Document 1. Specifically, as a general process of the pass rolling method, it is known that a rectangular material heated to a predetermined temperature in a heating furnace is first rolled in order by a rough rolling mill, an intermediate rolling mill, and a finishing rolling mill equipped with passes.

[0003] Also, particularly when manufacturing large and asymmetric products such as hat-shaped steel sheet piles, in order to manufacture them with the above-mentioned rough rolling mill, intermediate rolling mill, and finishing rolling mill, a large number of passes are required, large-scale equipment is required, the shaping method becomes complicated, and shape variations and shape defects of the products are likely to occur. Furthermore, a large number of rolls are required to manufacture steel sheet piles of different shapes. On the other hand, as shown in Patent Document 2, after rolling and manufacturing a steel sheet pile by hot rolling, bending (hereinafter also referred to as bending forming) is performed by cold working by roll forming, and a steel sheet pile with a width wider than the rolling equipment and a steel sheet pile with a high cross-sectional height are manufactured.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional pass rolling method exemplified in Patent Document 1 above, since rolling is performed in one pass with one pass rolling while performing pass shift in the intermediate rolling process to the finish rolling process, the total elongation of the material to be rolled is restricted according to the number of passes for rolling, and there is a problem that the elongation length of the product is small. Further, particularly when the plate thickness is thin, there are also problems such as the collapse of the shape of the end portion due to pass shift, and the elongation balance of each part in the cross section cannot be achieved during reverse rolling, resulting in warping and changes in the line length within the cross section. Furthermore, when manufacturing large steel sheet piling products by the conventional pass rolling method, the number of passes that can be arranged on one roll decreases, raising concerns about a decrease in manufacturing efficiency. Also, due to the increase in the peripheral speed difference between each roll, the friction between the material to be rolled and the roll becomes strong, causing scratches.

[0006] Also, in the method for manufacturing steel sheet piling as exemplified in Patent Document 2 above, bending is performed by cold working, and since the configuration is such that the corner portion of the material to be rolled is not directly pressed down using a backup roll which is a flat roll, it is difficult for direct plastic deformation to be applied to the corner portion, and there are problems such as ineffective bending being unable to be performed, and springback after forming being likely to increase because it is cold working. Also, when forming the web and flange at different timings using a plurality of forming rolls (backup rolls), there is a problem that the efficiency of bending forming decreases because the fulcrum shifts in the longitudinal direction of the material to be rolled. Also, in the method for manufacturing steel sheet piling described in Patent Document 2, the temperature during bending by cold working is set to a temperature below the A1 transformation temperature or a temperature below the recrystallization temperature. When bending is performed in such a temperature range, there may be problems such as a large processing load, deterioration of the material such as a decrease in elongation and toughness, and an increase in residual stress. Therefore, in order to improve these problems, it becomes necessary to arrange a large number of forming rolls, leading to problems such as an increase in the size of the equipment and complexity of the structure.

[0007] In order to solve the above problems, the inventors of the present invention conducted intensive research on bending forming for cross-sectional forming after rolling and manufacturing steel sheeting by hot rolling, and as a result, the following was clarified. In bending forming, angle changes occur in each part of the joint corresponding part of the material to be rolled (i.e., the part that becomes the joint of the product), and furthermore, the opening width of the joint corresponding part changes. Such changes in the angle and opening width of the joint corresponding part lead to deterioration of the joint shape when the steel sheeting is manufactured as a product. In steel sheeting products, if the joint shape collapses with respect to the desired shape, there are concerns such as an increase in driving resistance during construction and the detachment of the joint, which may cause problems in workability.

[0008] Therefore, in view of the above circumstances, an object of the present invention is to suppress changes in the angle and opening width that occur in the joint corresponding part of the material to be rolled by bending forming when manufacturing steel sheeting by bending forming, and to efficiently manufacture a steel sheeting product with a good joint shape.

Means for Solving the Problems

[0009] In order to achieve the above object, according to the present invention, at least a flange corresponding part, an arm corresponding part connected to one or both ends of the flange corresponding part, and a joint corresponding part connected to the tip of the arm corresponding part, for a material to be rolled having these parts, after performing rough rolling, intermediate rolling, and finish rolling by hot rolling, a method for manufacturing steel sheeting that performs bending forming in the hot state, wherein in the stage prior to the bending forming Final rolling preforming is performed in which the shape of the joint corresponding part is changed to a shape different from that of the product In the pre-forming of the shape of the joint corresponding part, the angle θ formed between the tip part and the bottom part of the joint corresponding part 1 , the angle θ formed between the reference plane parallel to the arm corresponding part and the bottom part of the joint corresponding part 2 , the angle θ formed between the connecting part of the arm corresponding part and the joint corresponding part and the bottom part of the joint corresponding part 3 , with respect to at least one or more dimensions of at least any one of the width M of the opening of the joint corresponding part, perform at least one or more of the following pre-formings (1) to (4). In the bending forming, at least at the corner part which is the boundary between the flange corresponding part and the arm corresponding part, bending is applied by upper and lower hole-type rolls so as to reduce the angle formed between the flange corresponding part and the arm corresponding part. A method for manufacturing a steel sheet pile, characterized by this. (1) The angle θ formed between the tip part and the bottom part of the joint corresponding part 1 is bent to a predetermined angle θ 1-1 predetermined based on the angle change caused by the bending forming (2) The angle θ formed between the reference plane parallel to the arm corresponding part and the bottom part of the joint corresponding part 2 is bent to a predetermined angle θ 2-1 predetermined based on the angle change caused by the bending forming (3) The angle θ formed between the connecting part of the arm corresponding part and the joint corresponding part and the bottom part of the joint corresponding part 3 is bent to a predetermined angle θ 3-1 predetermined based on the angle change caused by the bending forming (4) The width M of the opening of the joint corresponding part is set to a predetermined length M1 which is a value predetermined based on the length change caused by the bending forming

[0010] Here, the hot state means the temperature before the transformation of the material to be rolled is completed after hot rolling.

[0011] In the pre-forming of the shape of the joint corresponding part, with respect to at least one or more dimensions of at least any one of the angle θ formed between the tip part and the bottom part of the joint corresponding part and the width M of the opening of the joint corresponding part, perform at least one or more of the following pre-formings (1) to (4). The method for manufacturing a steel sheet pile according to claim 1, characterized by this. 1 (1) Pre-forming to make the angle θ in the joint corresponding part where the roll contacts the tip part larger than that of the product 1 (2) Pre-forming to make the angle θ in the joint corresponding part where the roll contacts the bottom part smaller than that of the product 1 (3) Pre-forming to make the width M of the opening in the joint corresponding part where the roll contacts the tip part larger than that of the product (4) Pre-forming to make the width M of the opening in the joint corresponding part where the roll contacts the bottom part smaller than that of the product ​

[0013] The predetermined angle θ in the state where the pre-forming of (1) to (3) above is performed 1-1 , θ 2-1 , θ 3-1 is the angle θ corresponding to the angle θ 1-1 , θ 2-1 , θ 3-1 in the desired product shape. The angle θ is an angle obtained by adding a value with the same magnitude but opposite sign to the change in the angles θ1, θ2, and θ3 caused by the bending forming with respect to the angle θ 1-2 , the angle θ 2-2 , the angle θ 3-2 in the desired product shape, the predetermined length M1 of the opening in the state where the pre-forming of (4) above is performed may be a length obtained by adding a value with the same magnitude but opposite sign to the change in the width M of the opening caused by the bending forming with respect to the length M2 of the opening in the desired product shape.

[0014] The predetermined angle θ in the pre-forming of (1) to (3) above 1-1 , θ 2-1 , θ 3-1 , and the predetermined length M1 in the pre-forming of (4) above may be based on at least one or more parameter changes of the following (5) to (8). (5) The change in the angle θ1 formed between the tip and the bottom surface of the joint corresponding part caused by the bending forming (6) The change in the angle θ2 formed between the reference plane parallel to the arm corresponding part and the bottom surface of the joint corresponding part caused by the bending forming (7) Change in the angle θ3 formed between the connecting portion of the arm corresponding portion and the joint corresponding portion generated by the bending forming, and the bottom surface portion of the joint corresponding portion (8) Change in the width M of the opening of the joint corresponding portion generated by the bending forming

[0016] A relief portion may be provided in a portion of the hole die roll of the bending forming machine that performs the bending forming, which faces the joint corresponding portion on the upper claw side and / or the lower claw side.

[0017] The steel sheet pile is a hat-shaped steel sheet pile, and in the bending forming, bending may be applied by upper and lower pass rolls so as to reduce the angle formed by the web corresponding portion and the flange corresponding portion at the corner portion which is the boundary between the web corresponding portion and the flange corresponding portion of the material to be rolled. The bending forming may be performed by changing the angle formed between the flange corresponding portion and the web corresponding portion of the rolled material, and the angle formed between the flange corresponding portion and the arm corresponding portion, and increasing the height of the rolled material to a desired product height by bending.

[0018] The steel sheet pile may be a Z-shaped steel sheet pile. The bending forming may be performed by changing the angle formed between the flange corresponding portion and the arm corresponding portion of the rolled material, and increasing the height of the rolled material to a desired product height by bending.

Advantages of the Invention

[0019] According to the present invention, it is possible to suppress the angle change and the change in the opening width generated in the joint corresponding portion of the rolled material by bending forming, and efficiently manufacture a steel sheet pile product with a good joint shape.

Brief Description of the Drawings

[0020]

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Figure 17

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the case of manufacturing a hat-shaped steel sheet pile as a steel sheet pile product will be described.

[0022] (Configuration of Rolling Line) FIG. 1 is an explanatory view of a rolling line L (dashed-dotted line in the figure) for manufacturing a hat-shaped steel sheet pile according to an embodiment of the present invention, and rolling mills and the like provided in the rolling line L. In FIG. 1, the rolling progress direction of the rolling line L is the direction indicated by the arrow, the material to be rolled flows in this direction, and rolling and bending forming are performed in each rolling mill and bending forming machine on the line, and the product is shaped. Further, in FIG. 1, a rolling method (so-called multi-pass rolling) in which the material to be rolled is reciprocated a plurality of times in the same rolling mill is also shown by a dashed-dotted line.

[0023] As shown in FIG. 1, a rough rolling mill 10, a first intermediate rolling mill 13, a second intermediate rolling mill 16, a finishing rolling mill 19, and a bending forming machine 20 are arranged in order on the rolling line L from the upstream. Further, an edger rolling mill 14 is arranged adjacent to the upstream side of the first intermediate rolling mill 13, and an edger rolling mill 17 is arranged adjacent to the downstream side of the second intermediate rolling mill 16.

[0024] In the rolling line L, a rectangular material (material to be rolled) heated in a heating furnace (not shown) is sequentially hot-rolled in the rough rolling mill 10 to the finishing rolling mill 19, and further formed by the bending forming machine 20 in the hot state to become a final product. Hereinafter, for the sake of explanation, the material to be rolled rolled by the rough rolling mill 10 is also called a rough shape material, the material to be rolled rolled by the first intermediate rolling mill 13 to the second intermediate rolling mill 16 is called an intermediate material, and the material to be rolled rolled by the finishing rolling mill 19 is also called a finishing material 19a. That is, the material obtained by forming (changing the cross section) the finishing material 19a by the bending forming machine 20 becomes the final product (that is, a hat-shaped or U-shaped steel sheet pile product).

[0025] Here, since the rough rolling mill 10, the first intermediate rolling mill 13, the second intermediate rolling mill 16, the finishing rolling mill 19 arranged on the rolling line L, and the edger rolling mills 14 and 17 arranged therewith are general facilities conventionally used in the manufacture of steel sheet piles, the description of their detailed device configurations and the like is omitted in this specification.

[0026] (Configuration of the bending forming machine) Next, the detailed configuration of the bending forming machine 20 will be described with reference to the drawings. FIG. 2 is a schematic side cross-sectional view of the bending forming machine 20, and FIG. 3 is a schematic front view of the bending forming machine 20. The bending forming machine 20 shown in FIGS. 2 and 3 bends the finished material 19a finish-rolled by the finishing rolling mill 19. Note that FIG. 3 shows a schematic front view of the first stand 22 included in the bending forming machine 20 described below. Here, in the present embodiment, the case where the bending forming machine 20 is composed of two forming stands (the forming stands 22 and 23 described below) is illustrated and described, but the bending forming machine 20 may be composed of a single stand or any plurality of stands.

[0027] As shown in FIG. 2, the bending forming machine 20 according to the present embodiment includes two forming stands 22 and 23 (hereinafter also referred to as the upstream first stand 22 and the downstream second stand 23) arranged adjacent to each other in series. Further, as shown in FIG. 3, forming passes (passes 45 and 55 described later) composed of an upper pass roll and a lower pass roll are engraved on each of the stands 22 and 23, and the pass shapes are different between the first stand 22 and the second stand 23.

[0028] Here, the roll configurations and pass shapes of the first stand 22 and the second stand 23 will be described. FIG. 4 is a schematic enlarged front view showing the pass shape of the first stand 22, and FIG. 5 is a schematic enlarged front view showing the pass shape of the second stand 23. Note that in FIG. 4, the cross-sectional shape of the finish material 19a in the state before forming by the bending machine 20 is illustrated by a dashed line, and in FIG. 5, the cross-sectional shape of the finish material 19a' in the state before forming at the second stand 23 is illustrated by a dashed line. Also, hereinafter, the case of bending and forming a rolled material having a substantially hat-shaped cross-section in an upward-opening posture (with the web corresponding portion described later facing downward and the arm corresponding portion positioned upward) will be exemplified and described.

[0029] As shown in FIGS. 3 and 4, in the first stand 22, an upper pass roll 40 and a lower pass roll 41 are provided and supported by a housing 44, and a pass 45 is formed by the upper pass roll 40 and the lower pass roll 41. The shape of the pass 45 from the portion corresponding to the flange to the portion corresponding to the joint is one step before the shape of a hat-shaped steel sheet pile product (i.e., a substantially hat-shaped steel sheet pile product shape). The pass 45 changes the angles formed by the portion corresponding to the flange of the finish material 19a (i.e., the flange corresponding portion), the portion corresponding to the web of the finish material 19a (i.e., the web corresponding portion), and the portion corresponding to the arm of the finish material 19a (i.e., the arm corresponding portion), respectively, and bends and forms the height and width of the finish material 19a into a predetermined shape (i.e., a cross-sectional shape approximated to the product). Particularly when manufacturing a hat-shaped steel sheet pile, the rolled material (rough material to finish material 19a) is rolled in a shape with a low height in the roughing mill 10 to the finishing mill 19, and a method is adopted in which the bending machine 20 bends and forms the height of the rolled material to the desired product height. Thereby, it becomes possible to manufacture a large-sized hat-shaped steel sheet pile product.

[0030] Also, as shown in FIG. 5, an upper pass roll 50 and a lower pass roll 51 are provided on the second stand 23 and supported by a housing 54, and a pass 55 is formed by the upper pass roll 50 and the lower pass roll 51. This pass 55 has a shape close to the desired product shape, and changes the angles formed by the portion corresponding to the flange formed at the first stand 22 of the bending machine 20 (i.e., the flange corresponding portion) and the portion corresponding to the web of the finishing material 19a (i.e., the web corresponding portion), and the portion corresponding to the arm (i.e., the arm corresponding portion), respectively, to form the flange shape, the arm shape, and the joint shape into a predetermined shape (i.e., the product shape). That is, at this second stand 23, forming is performed to deform the inclination angle of the flange corresponding portion, which was insufficient with respect to the product shape in the forming at the first stand 22, to an angle corresponding to the product shape.

[0031] Here, the roll gaps in the above-described pass 45 and pass 55 during bending (the roll gap between the upper pass roll 40 and the lower pass roll 41 and the roll gap between the upper pass roll 50 and the lower pass roll 51) are configured to be larger than the thicknesses of the flange corresponding portion and the web corresponding portion of the finishing material 19a. That is, in the bending machine 20, no thickness reduction of the finishing material 19a is performed, and the pass rolls of the first stand 22 and the second stand 23 and the finishing material 19a are configured to come into contact and perform bending only at some predetermined locations (see FIG. 7) described later.

[0032] (Bending of the material to be rolled) Next, the forming of the material to be rolled in the above-described stands 22 and 23 will be described. FIG. 6 is an explanatory view of the shape change of the material to be rolled (finished material 19a) bent and formed in the first stand 22 and the second stand 23. (a) is a schematic cross-sectional view before processing in the first stand 22, (b) is a schematic cross-sectional view during processing in the first stand 22, and (c) is a schematic cross-sectional view during processing in the second stand 23. As shown in FIG. 6(a), the finished material 19a has a substantially hat shape, and includes a web corresponding portion 60 that is substantially horizontal, flange corresponding portions 62 and 63 connected by corner portions 70 at both ends of the web corresponding portion 60 at a predetermined angle (shown as angle α in the figure) larger than the product shape, and arm corresponding portions 65 and 66 connected to different ends of each of the flange corresponding portions 62 and 63 via corner portions 71 on the side different from the connection side with the web corresponding portion, and joint corresponding portions 68 and 69 formed at the tips of the arm corresponding portions 65 and 66. Further, the thickness of the finished material 19a has become substantially the thickness of the product by rolling in the finishing rolling mill 19, and the shapes of the joint corresponding portions 68 and 69 have also become substantially the product joint shape.

[0033] The finished material 19a shown in FIG. 6(a) is bent and formed in the pass die 45 of the first stand 22 so that the angle α formed by the web corresponding portion 60 and the flange corresponding portions 62 and 63 becomes smaller (becomes the angle α1 shown in FIG. 6(b)), and has a height close to the desired product height as shown in FIG. 6(b). That is, in the first stand 22, bending forming is performed so that the height of the finished material 19a increases.

[0034] Next, as shown in FIG. 6(c), in the pass die 55 of the second stand 23, the finished material 19a is bent and formed into a substantially product shape.

[0035] (Contact portion with the pass roll in bending forming) FIG. 7 is an explanatory view of the contact portions of the finishing material 19a in the bending machine 20, and FIGS. 7(a) and 7(b) each show an example of the contact portion. In FIG. 7, the contact portion is illustrated by a thick line. In the pass die 45 of the first stand 22 and the pass die 55 of the second stand 23, each pass die roll and the finishing material 19a are in contact only at a part of a predetermined location, and no reduction in plate thickness is performed. Here, "contact" means that at least the material and the pass die roll are in contact, and it may also be in a state where a force for pressing the material is applied.

[0036] Specific contact locations between the pass die roll and the finishing material 19a are, for example, as shown in FIG. 7(a), the inner corners 70a, 70b of the boundary between the web corresponding portion 60 and the flange corresponding portions 62, 63, and the inner corners 71a, 71b of the boundary between the flange corresponding portions 62, 63 and the arm corresponding portions 65, 66. In addition, by bringing the lower central portion 60a of the lower surface of the web corresponding portion 60 shown in FIG. 7(a) into contact, the bending of the angle formed by the flange corresponding portions 62, 63 and the web corresponding portion 60 can be efficiently performed. Also, during bending, since the web corresponding portion 60 tends to warp downward in the figure, by bringing the lower pass die rolls 41, 51 into contact with the lower central portion 60a, which is a position away from both sides of the web corresponding portion 60 (i.e., the corner portions 70), a bending moment can be effectively applied to the corner portions 70.

[0037] Also, at least in the second stand 23, which is the final stand, the upper surfaces (outer surfaces) 65a, 66a of the arm corresponding portions 65, 66 become contact portions in order to make the arm corresponding portions 65, 66 substantially horizontal. In addition, as shown in FIG. 7(a), in the pass die 45 of the first stand 22 and the pass die 55 of the second stand 23, the upper inner portions 62a, 63a of the flange corresponding portions 62, 63 of the finishing material 19a are brought into contact with the upper pass die rolls 40, 50, and the lower outer portions 62b, 63b of the flange corresponding portions 62, 63 are brought into contact with the lower pass die rolls 41, 51. By bringing the locations shown in FIG. 7(a) into contact, three-point bending due to the pass die roll shape is generated at the corner portions 70, 71, and high-precision bending can be performed.

[0038] Also, as shown in Fig. 7(b), in addition to the location described in Fig. 7(a) above, the upper surfaces (outer surfaces) 68a and 69a of the joint corresponding portions 68 and 69 may be brought into contact with the upper hole rolls 40 and 50. By bringing the location shown in Fig. 7(b) into contact, forming can be performed such that the joint corresponding portions 68 and 69 are also substantially horizontal, and furthermore, highly accurate bending forming can be performed.

[0039] (Deterioration of the shape of the joint corresponding portion) Here, when performing the bending forming of the finishing material 19a as described with reference to Figs. 6 and 7, as the bending forming angle increases, the force (pressure) associated with the contact from the upper surfaces of the arm corresponding portions 65 and 66 and the joint corresponding portions 68 and 69 becomes stronger. As a result, there is a problem that the shape after the bending forming deteriorates in the joint corresponding portions 68 and 69. Hereinafter, this problem will be described with reference to Figs. 8, 9 and Table 1.

[0040] Fig. 8 is an explanatory diagram showing an enlarged view of the desired shape of the shape of the joint corresponding portion 69 having an upward opening shape. As shown in Fig. 8, the joint corresponding portion 69 is composed of a joint connecting portion 69a which is a connecting portion with the arm corresponding portion 66, a joint bottom surface portion 69b constituting the joint shape, and a joint tip portion 69c. Further, an opening 69d is provided in the joint corresponding portion 69.

[0041] Here, as shown in FIG. 8, in the joint corresponding portion 69, the joint bottom surface portion 69b and the joint tip portion 69c are connected at a desired angle θ1 (hereinafter also referred to as the tip angle θ1). Further, the joint bottom surface portion 69b shows a state inclined with respect to the arm corresponding portion 66 (here, in the horizontal direction), and this inclination angle will be described as θ2 (hereinafter also referred to as the joint bottom angle θ2). In the case of a hat-shaped steel sheet pile, the desired angle of the arm corresponding portion 66 is 0° (horizontal), and this inclination angle θ2 is also defined as the angle θ2 formed between the joint bottom surface portion 69b and a reference plane (here, the horizontal line: the broken line in the figure) parallel to the arm corresponding portion 66. However, this joint bottom angle θ2 may be 0° before bending when the desired product is 0° (that is, the joint bottom surface portion 69b is horizontal). Also, the joint connecting portion 69a and the joint bottom surface portion 69b are connected at a desired angle θ3 (hereinafter also referred to as the connecting portion angle θ3).

[0042] Further, FIG. 9 is an explanatory view of the shape of the joint corresponding portion 68 having a downward-opening shape. As shown in FIG. 9, similar to the above joint corresponding portion 69, the joint corresponding portion 68 is composed of a joint connecting portion 68a, a joint bottom surface portion 68b, and a joint tip portion 68c. Also, an opening portion 68d is provided. The various angles in the joint corresponding portion 68 are basically the same as those shown in FIG. 8, and the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 are configured as shown in the figure respectively.

[0043] The inventors of the present invention confirmed that by bending, the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening widths M of the opening portions 68d and 69d shown in FIGS. 8 and 9 change, and the joint shape changes from the desired shape. Therefore, the inventors verified the respective values of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M during the bending of the hat-shaped steel sheet pile. Note that the tip angle θ1 before bending in this verification is 36°, the joint bottom angle θ2 is 0°, and the connecting portion angle θ3 is 105.8°, and these values are the desired values in the hat-shaped steel sheet pile product. Note that in the following verification, the "lower claw side" refers to the joint corresponding portion 68 having a downward-opening shape (see FIG. 9), and the "upper claw side" refers to the joint corresponding portion 69 having an upward-opening shape (see FIG. 8).

[0044] The following Table 1 shows the changes in the tip angle θ1, joint bottom angle θ2, connecting part angle θ3, and opening width M in the bending forming without pre-forming.

[0045]

Table 1

[0046] As shown in Table 1, the tip angle θ1 before bending forming (after finish rolling) is 36° on both the upper claw side and the lower claw side. However, due to the bending forming, on the upper claw side, the tip of the joint corresponding part contacts the roll, causing θ1 on the upper claw side to decrease to 31.2°, and on the lower claw side, the joint bottom of the joint corresponding part contacts the roll, resulting in θ1 on the lower claw side increasing to 37.4°. Since the desired tip angle θ1 for the product shape is 36°, the shape change of the joint corresponding part as shown in Table 1 leads to deterioration of the product shape and is thus undesirable.

[0047] Also, as shown in Table 1, the joint bottom angle θ2 before bending forming is 0° on both the upper claw side and the lower claw side. During the bending forming, along with the change in the angle formed by the web corresponding part 60 and the flange corresponding parts 62, 63, the arm corresponding parts 65, 66 and the joint corresponding parts 68, 69 greatly incline upward with respect to the horizontal plane, and then the upper surfaces (outer surfaces) of the arm corresponding parts 65, 66 and the joint corresponding parts 68, 69 contact the upper hole die roll and change in the horizontal direction. As a result, this joint bottom angle θ2 fluctuates greatly during the bending forming. Although it almost returns to 0° (-0.2°) on the lower claw side after the bending forming, on the upper claw side where the tip of the joint corresponding part contacts the roll, it does not become horizontal and is inclined upward by 1.9°. Since the desired joint bottom angle θ2 for the product shape is 0°, the change in the joint bottom angle θ2 is undesirable.

[0048] Also, as shown in Table 1, the connecting part angle θ3 before bending forming is 105.8° on both the upper claw side and the lower claw side. In contrast, it can be seen that after the bending forming, the upper claw side changes slightly to 105.5° and the lower claw side changes slightly to 105.9°.

[0049] Also, due to the changes in the tip angle θ1 and the joint bottom angle θ2 described above, as shown in Table 1, the amount of change in the opening width M in bending is -1.5 mm on the upper claw side and 0.7 mm on the lower claw side, and any opening width M fluctuates due to bending. That is, it has changed from the value of the opening width M desired as the product shape, and there may be cases where a good joint shape cannot be obtained in the product.

[0050] As described above with reference to FIGS. 8 and 9 and Table 1, in bending, there is a problem that the shape of the joint corresponding portion changes, and as a result, a desired product shape cannot be obtained.

[0051] (Pre-forming) Regarding changes in various dimensions such as the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M, in bending, since the rolled material is configured to include a portion that does not directly contact the roll, simply changing the groove shape of the grooved roll for bending may not result in a product with an appropriate desired shape.

[0052] Therefore, the inventors of the present invention have conducted intensive research on the shape change of the joint corresponding portion in bending, and considering the shape change of the joint corresponding portion in the above-described bending, it has been found that a desired joint shape can be obtained after bending by changing the shape of the joint corresponding portion in advance at a stage prior to bending. Specifically, in finish rolling, a process is performed to bend the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 of the joint corresponding portion to a predetermined angle θ 1-2 、θ 2-2 、θ 3-2 different from the angles θ 1-1 、θ 2-1 、θ 3-1 in the product shape. Also, a process is performed to change the opening width M of the joint corresponding portion to a length M1 different from the length M2 of the opening width in the product. Thereby, after bending, a joint corresponding portion having a desired shape (i.e., a substantially product shape) can be obtained.

[0053] In the process of pre-bending the tip angle θ1, the suitable bending angle is determined according to the angle change of the tip angle θ1 that occurs in the bending forming. Specifically, for example, an angle of the same magnitude as the angle change that occurs in the tip angle θ1 during bending forming, but with the opposite sign (the direction that cancels out the angle change that occurs in the bending forming), is basically pre-bent to a predetermined angle θ 1-1 That's all. That is, the tip angle θ1 is pre-formed, and it is set to a predetermined angle θ 1-1 which is a value predetermined based on the angle change caused by the bending forming. Referring to Table 1 above for explanation, the angle change in the bending forming of the tip angle θ1 on the upper claw side is -4.8° (changing from 36° to 31.2°), and the angle change in the tip angle θ1 on the lower claw side is 1.4° (changing from 36° to 37.4°). Therefore, when the angle of the tip angle θ1 after bending forming is desired to be a desired angle (for example, the tip angle θ 1―2 ) of the product, for the tip angle θ1 on the upper claw side, an angle change of approximately 5° (strictly 4.8°) is imparted in advance with respect to the desired angle, and for the tip angle θ1 on the lower claw side, an angle change of approximately -1.5° (strictly -1.4°) is imparted in advance with respect to the desired angle, so that the above-mentioned predetermined angle θ 1-1 is set.

[0054] That is, when imparting an angle change to the tip angle θ1, when an angle change occurs such that the angle decreases in the bending forming, an angle should be imparted in advance so that θ1 is larger than the desired angle after the bending forming. When an angle change occurs such that the angle increases in the bending forming, it is necessary to impart an angle in advance so that θ1 is smaller than the desired angle after the bending forming. That is, in the case shown in Table 1 above, since the tip angle θ1 on the upper claw side decreases from 36° to 31.2°, it is necessary to impart an angle change that increases the tip angle θ1 in advance at the joint corresponding part on the upper claw side. On the other hand, since the tip angle θ1 on the lower claw side increases from 36° to 37.4°, it is necessary to impart an angle change that decreases the tip angle θ1 in advance at the joint corresponding part on the lower claw side.

[0055] Also, regarding the joint bottom angle θ2, when it increases by 1.9° on the upper claw side as shown in Table 1, it is necessary to give an angular change such that the joint bottom angle θ2 is decreased in advance at the joint corresponding part on the upper claw side. That is, the joint bottom angle θ2 is preformed, and a predetermined angle θ which is a value determined in advance based on the angular change caused by the bending forming is used. 2-1 This is all that is necessary.

[0056] Regarding the connecting part angle θ3 as well, an angular change may be given in advance in the same way. However, when the amount of change is small as shown in Table 1 (for example, when the amount of change is less than 0.5°), it is not necessary to give an angular change in advance. That is, the connecting part angle θ3 is preformed, and a predetermined angle θ which is a value determined in advance based on the angular change caused by the bending forming is used. 3-1 This is all that is necessary.

[0057] Table 2 below shows the changes in the tip angle θ1, joint bottom angle θ2, connecting part angle θ3, and opening width M in the bending forming when the preforming according to the present invention is performed. Here, the values shown as "after finish rolling" in Table 2 are the above-mentioned predetermined angles θ 1-1 , θ 2-1 , θ 3-1 and the predetermined length M1. Note that Table 2 was measured for the same joint corresponding part as shown in Table 1 above, and the tip angle in the desired product shape is 36°.

[0058]

Table 2

[0059] As described above, since it is desirable that the angular change pre-given to the tip angle θ1 is the same magnitude as the angular change that occurs during the bending forming and has the opposite sign, a 5° angular change is pre-given to the tip angle θ1 on the upper claw side, and a -1.5° angular change is pre-given to the tip angle θ1 on the lower claw side. Specifically, the tip angle θ1 on the upper claw side is set to 41° (36° + 5°) in advance, and the tip angle θ1 on the lower claw side is set to 34.5° (36° - 1.5°) in advance.

[0060] As shown in Table 2, when bending and forming is performed after imparting an angular change in advance and setting the tip angle θ1 on the upper claw side to 41° and the tip angle θ1 on the lower claw side to 34.5°, the tip angle θ1 on both the upper claw side and the lower claw side becomes approximately 36° (strictly 35.7°, 35.9°), which is the desired angle, after the bending and forming. That is, as described above, it can be understood that by imparting the previously measured angle to the tip angle θ1 of the joint corresponding portion before the bending and forming and changing the angle, the tip angle θ1 of the joint corresponding portion after the bending and forming can be made the desired angle.

[0061] Also, as shown in Table 2, the joint bottom angle θ2 in the desired product shape is 0°. As pre-forming, an angle of -2° (downward from the horizontal) was imparted to the joint bottom angle θ2 on the upper claw side in advance to the joint corresponding portion, and the lower claw side was left at 0°. When bending and forming is performed from this state, both the upper claw side and the lower claw side become approximately 0° (strictly -0.1°, -0.2°) after the bending and forming, and the desired joint bottom angle θ2 is obtained. When the joint bottom angle θ2 on the lower claw side changes from the desired angle, since the joint bottom surface portion on the lower claw side contacts the upper die rolls 40 and 50 during the bending and forming, the joint bottom angle θ2 can be corrected by changing the die shape of the corresponding portions (contact portions) of the upper die rolls 40 and 50 in the direction opposite to the change amount of the joint bottom angle θ2. This point will be described later.

[0062] Also, as shown in Table 2, regarding the connecting portion angle θ3 of the joint corresponding portion, since the change amount of the angle was minute under the current conditions (see Table 1), no angular change was imparted in advance. In that case, the connecting portion angle θ3 changes slightly during the bending and forming. Of course, if pre-forming is performed on the connecting portion angle θ3, the connecting portion angle θ3 of the joint corresponding portion can be made closer to the desired angle (here 105.8°).

[0063] Also, when a process of changing the opening width M of the joint corresponding portion to a length different from the length of the opening width in the product is performed in advance before bending, the suitable length for the change is determined according to the length change of the opening width M that occurs during bending. Specifically, it is preferable to set the length that is substantially the same as the length change of the opening width M that occurs during bending and has the opposite sign as the length to be changed in advance. Taking the case of Table 1 as an example, the length change of the opening width M on the upper claw side during bending is -1.5 mm, and the length change of the opening width M on the lower claw side during bending is 0.7 mm. Therefore, when the opening width M after bending is desired to be a desired length (for example, the opening width M2 of the product), a length change of 1.5 mm may be given to the opening on the upper claw side in advance, and a length change of -0.7 mm may be given to the opening on the lower claw side in advance. That is, the opening width M may be preformed and set to a predetermined length M1, which is a value determined in advance based on the length change caused by bending.

[0064] That is, when a length change is given to the opening in advance, when the opening width M becomes shorter (narrower) during bending, a length change that makes the opening width M larger (wider) than the desired length after bending should be given in advance. On the other hand, when the opening width M becomes longer (wider) during bending, it is necessary to give a length change that makes the opening width M smaller (narrower) than the desired length after bending.

[0065] As described above, since the length change given to the opening in advance is desirably substantially the same as the length change of the opening width that occurs during bending and has the opposite sign, a length change of 1.5 mm is given to the opening width M on the upper claw side in advance (that is, the opening is widened), and a length change of -0.7 mm is given to the opening width M on the lower claw side in advance (that is, the opening is narrowed). Specifically, while the desired opening width of the opening in the final product is 14 mm, the opening width M on the upper claw side is set to 15.5 mm, and the opening width M on the lower claw side is set to 13.3 mm.

[0066] As shown in Table 2, when the opening width of the opening is changed in advance and bending forming is performed with the opening width M on the upper claw side being 15.5 mm and the opening width M on the lower claw side being 13.3 mm, after bending forming, the opening width M of both the upper claw side and the lower claw side openings becomes approximately the desired width (13.8 mm close to the opening width of the product shape). That is, it can be understood that by imparting a change in the opening width of a predetermined length measured in advance to the joint corresponding portion, the opening width of the joint corresponding portion after bending forming can be made the desired length (width). Of course, since the opening width M also changes when the values of the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 change, it is preferable to adjust the opening width M in combination with changes in the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 of the joint corresponding portion.

[0067] Also, with respect to the pre-forming amounts of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M, the magnitudes of the changes in these during bending forming may not be completely equal. This is because a change in one angle or length somewhat affects the changes in other angles. Therefore, the values of the angle changes and length changes in the present invention may include these errors.

[0068] (Function and effect) As described above, by changing the shape of the joint corresponding portion in advance, specifically, the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M, in the stage before bending forming, a desired joint shape can be obtained after bending forming. Therefore, it is possible to suppress the poor joint shape of the product associated with changes in the angle and opening width of the joint corresponding portion, which is a problem in the manufacturing method of steel sheet piles using bending forming, and it is possible to efficiently manufacture steel sheet pile products with a good joint shape.

[0069] In addition, in the above-described embodiments, when changing the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M by pre-forming, only one of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M may be changed, or two or more of these four parameters may be selected and changed. Note that, regarding the opening width M, the opening width M also changes by changing the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3. Therefore, except for the case where only the opening width M is changed, the value of the opening width M may be adjusted by changing at least one of the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3. Further, in the case where only the opening width M is changed, the length of the joint tip portion may be adjusted at the stage of the material to be rolled.

[0070] More specifically, the correlation between the changes in the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M is obtained by bending, and based on this correlation, the amount of angle change applied to the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 in pre-forming and the amount of change in the length of the opening width M may be determined. As described above, when any one of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M is changed, the other values also change. Therefore, when the actual measured values of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M are measured after bending, for example, when only the value of the tip angle θ1 does not reach the desired value, if an angle change based on the actual measured value is applied only to the tip angle θ1 in pre-forming, the other values will change and the other values may also deviate from the desired values. Therefore, when applying an angle change to the tip angle θ1, it is preferable to consider the correlation with the other joint bottom angle θ2, connecting portion angle θ3, and opening width M, and also apply changes to the joint bottom angle θ2, connecting portion angle θ3, and opening width M so that all values including the tip angle θ1 ultimately become the desired values. Specifically, for example, when changing the tip angle θ1, it may be possible to obtain in advance by simulation or the like how the other joint bottom angle θ2, connecting portion angle θ3, and opening width M change. In practice, since the product has a certain dimensional tolerance, an adjustment amount may be set within a certain range for the angle of the joint corresponding portion and the amount of change in the opening width M in bending so that it falls within the tolerance of the product.

[0071] 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 form. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope of the idea described in the claims, and it is naturally understood that those also belong to the technical scope of the present invention.

[0072] In the above-described embodiment, although it has been described that the angular change and the opening width change to be pre-given to the joint corresponding portion are carried out in the stage before the bending forming, specifically, when performing the joint bending by the finishing rolling mill, it is preferable to give the angular change and the opening width change. Thereby, compared with the prior art, it is possible to manufacture a steel sheet pile product with a good joint shape without increasing the manufacturing process and without introducing new equipment or the like. Therefore, the productivity and the yield can be improved, and furthermore, the cost increase can be suppressed.

[0073] In addition to the above-described embodiment, when the tip angle θ1 on the upper claw side and / or the joint bottom angle θ2 on the lower claw side changes from the desired angle, it may be dealt with by changing the shape of at least one of the upper hole-type rolls 40 and 50 of each stand constituting the bending forming machine 20. That is, pre-forming may be performed with respect to at least one of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M in the bending forming, and different means (changing the hole shape) may be used to deal with the tip angle θ1 and / or the joint bottom angle θ2. Specifically, in any of the upper hole-type rolls 40 and 50, the portion where the joint corresponding portion on the upper claw side and / or the lower claw side contacts is changed to a hole shape corresponding to the change in the tip angle θ1 or the joint bottom angle θ2. For example, the gap between the joint tip and the roll may be changed on the upper claw side. Further, the portion where the joint bottom on the lower claw side contacts may be changed in the direction opposite to the direction in which the joint bottom angle θ2 changes, in accordance with the amount of change, to correct the joint bottom angle θ2. Hereinafter, specific embodiments of the change in the hole shape will be described.

[0074] FIG. 14 is a schematic explanatory view showing an example of a hole shape in which the shape is changed with respect to the change in the tip angle θ1 on the upper claw side. FIG. 15 is a schematic explanatory view showing an example of a hole shape in which the shape is changed with respect to the change in the joint bottom angle θ2 on the lower claw side. That is, FIGS. 14 and 15 are schematic enlarged views showing an example of the configuration in the vicinity of the joint corresponding portion of the upper hole-type rolls 40 and 50 of the bending forming machine 20.

[0075] As shown in Fig. 14, in either of the upper hole-type rolls 40 and 50, a relief portion 80 may be provided at a portion facing the joint corresponding portion on the upper claw side (the joint corresponding portion 69 shown in Fig. 8). The relief portion 80 is configured, for example, by making the gap L2 between the joint corresponding portion 69 and the roll larger than the gap L1 between the arm corresponding portion 66 and the roll as shown in the drawing (i.e., L1 < L2). The difference between L2 and L1 may be about 0.5 mm to 2 mm, for example. Thereby, when the reduction in the tip angle θ1 and the opening width M of the joint corresponding portion on the upper claw side is large, it is possible to mitigate the increase in the preforming amounts of the tip angle θ1 and the opening width M in the preforming.

[0076] Also, as shown in Fig. 15, in either of the upper hole-type rolls 40 and 50, a relief portion 81 may be provided at a portion facing the joint corresponding portion on the lower claw side (the joint corresponding portion 68 shown in Fig. 9). As a specific configuration of the relief portion 81, for example, a configuration in which the distance between the portion in contact with the arm corresponding portion 65 of the upper hole-type rolls 40 and 50 and the portion in contact with the joint bottom surface portion 68b of the joint corresponding portion 68 is larger than the distance between the arm corresponding portion 65 and the joint bottom surface portion 68b of the finishing material 19a can be mentioned.

[0077] As shown in Fig. 15, the roll shape of the relief portion 81 may be, for example, an arc shape having a predetermined radius of curvature in a cross-sectional view. Also, in addition to the arc shape, a straight line or a combination of a straight line and an arc may be used. In response to the change in the joint bottom angle θ2 in the joint corresponding portion 68 on the lower claw side, the joint bottom angle θ2 can be formed into a desired angle by moving the portion facing the joint corresponding portion 68 in the outer direction (the direction away from the joint corresponding portion 68).

[0078] Note that the configuration provided with the relief portions 80 and 81 described above may be applied to at least one of the upper hole-type rolls 40 and 50 of each stand of the bending machine 20, and preferably, it may be applied to the final stand (here, the second stand 23). Also, when providing the relief portion 81 in the hole-type roll of the bending machine 20, it is preferable not to perform the preforming regarding the joint bottom angle θ2 on the lower claw side according to the present embodiment.

[0079] In addition, in the above-described embodiment, the case of manufacturing the hat-shaped steel sheet pile product in an upward-opening posture (with the arm-corresponding portion above the web-corresponding portion) has been exemplified and described. However, the present invention can also be applied to the case of manufacturing in the reverse downward-opening posture (with the arm-corresponding portion below the web-corresponding portion). In this case, it may be considered that the opening direction of the joint (or the joint-corresponding portion) is arranged in the reverse direction.

[0080] In addition, in the above-described embodiment, the case of manufacturing a hat-shaped steel sheet pile as the final product has been exemplified and described. However, the application scope of the present invention is not limited to this. For example, it can be applied to any steel sheet pile product having a joint with an opening, such as a U-shaped steel sheet pile or a Z-shaped steel sheet pile.

[0081] (Modification example) In the above-described embodiment, the description has been made based on the shape of the joint provided in a general hat-shaped steel sheet pile. However, there are various shapes of joints for steel sheet piles. For example, there is a so-called "flat joint" in which the left and right joints are asymmetrically configured, one is a so-called straight joint, the other is a so-called bent joint, and when a plurality of steel sheet piles are connected, the outer surface becomes flat by fitting these joints. FIG. 10 is an explanatory diagram showing an example of a steel sheet pile having a flat joint, (a) is a hat-shaped steel sheet pile having a flat joint, and (b) is a schematic cross-sectional view of a Z-shaped steel sheet pile having a flat joint. In the following modification examples, the case where the present invention technology is applied to each of a Z-shaped steel sheet pile and a hat-shaped steel sheet pile provided with a flat joint will be described. In the following modification examples, components having the same functional configuration as those in the above-described embodiment may be denoted by the same reference numerals, and the description thereof may be omitted.

[0082] (First modification example) The bending of the Z-shaped steel sheet pile is also carried out by a bending machine equipped with upper and lower pass rolls in the same manner as in the above embodiment. Since only the pass shape is different from the above embodiment, the detailed description of the bending during the manufacture of the Z-shaped steel sheet pile is omitted here, and only the outline description is given. FIG. 11 is an explanatory view of the contact portion of the material (finished material) in the bending, and (a), (b), and (c) show examples of the contact portion, respectively. The portion shown by the thick line in FIG. 11 is the contact portion between the pass roll and the material during bending.

[0083] Here, as shown in FIGS. 10(b) and 11, in the bending of the Z-shaped steel sheet pile provided with the flat joint, the left and right joint corresponding portions are respectively the straight joint corresponding portion 75 and the bent joint corresponding portion 76. Further, the Z-shaped steel sheet pile has a flange corresponding portion 77 with a substantially linear cross section at its center. And it has a left arm corresponding portion 72 connecting the flange corresponding portion 77 and the straight joint corresponding portion 75, and further has a right arm corresponding portion 73 connecting the flange corresponding portion 77 and the bent joint corresponding portion 76.

[0084] When manufacturing the Z-shaped steel sheet pile using bending, when reducing the flange-arm angle and expanding the height (the vertical distance between the left arm corresponding portion 72 and the right arm corresponding portion 73), there is a problem that the shape after bending deteriorates due to the bending moment acting on the straight joint corresponding portion 75 and the bent joint corresponding portion 76. Hereinafter, this problem will be described with reference to FIGS. 12, 13, and Table 3.

[0085] FIG. 12 is an enlarged explanatory view of the shape of the straight joint corresponding portion 75, and FIG. 13 is an enlarged explanatory view of the shape of the bent joint corresponding portion 76. As shown in FIG. 12, the straight joint corresponding portion 75 is composed of a joint connecting portion 75a which is a connecting portion with the left arm corresponding portion 72, a joint bottom surface portion 75b and a joint tip portion 75c constituting the joint shape. Further, an opening 75d is provided in the straight joint corresponding portion 75. As shown in FIG. 13, the bent joint corresponding portion 76 is similarly composed of a joint connecting portion 76a, a joint bottom surface portion 76b, a joint tip portion 76c, and an opening 76d.

[0086] Here, as shown in FIG. 12, in the straight joint corresponding portion 75, the joint bottom surface portion 75b and the joint tip portion 75c are connected at a desired angle θ1 (tip angle θ1). Further, the joint bottom surface portion 75b is shown in an inclined state with respect to the left arm corresponding portion 72, and the inclination angle, which is the angle between the joint bottom surface portion 75b and the left arm corresponding portion 72, will be described as θ2 (joint bottom angle θ2). This inclination angle θ2 is also defined as the angle θ2 formed between the joint bottom surface portion 75b and the extension line of the left arm corresponding portion 72 (or a reference plane parallel to the left arm corresponding portion 72). However, this joint bottom angle θ2 may be 0° before bending when it is 0° in a desired product. Also, the joint connecting portion 75a and the joint bottom surface portion 75b are connected at a desired angle θ3 (connecting portion angle θ3). The joint tip portion 75c and the joint connecting portion 75a are separated by a desired opening width M. Note that in the bent joint corresponding portion 76 shown in FIG. 13 as well, the configurations of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M are the same as those of the straight joint corresponding portion 75.

[0087] In order to confirm that by bending, the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M of the opening 75d shown in FIG. 12 change, and the joint shape changes from the desired shape, the present inventors verified the respective values of the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M during the bending of the Z-shaped steel sheet pile. In this case, the change in the flange-arm angle is 22° in the direction in which the angle becomes smaller. Note that before bending in this verification, the tip angle θ1 is 42°, the joint bottom angle θ2 is 0°, and the connecting portion angle θ3 is 95.7°, and these values are the desired values in the Z-shaped steel sheet pile product. Also, in this verification, the same verification was performed for the bent joint corresponding portion 76.

[0088] Table 3 below shows the changes in the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M in the bending of the Z-shaped steel sheet pile for the straight joint corresponding portion 75 and the bent joint corresponding portion 76 without performing pre-forming.

[0089]

Table 3

[0090] As shown in Table 3, the tip angle θ1 before bending is 42° for both the straight joint corresponding part 75 and the bent joint corresponding part 76. However, it can be seen that by bending, the tip angle θ1 increases to 42.4° in the straight joint corresponding part 75 and decreases to 41.5° in the bent joint corresponding part 76. Since the desired tip angle θ1 as the product shape is 42°, the shape change of the joint corresponding part leads to deterioration of the product shape, which is not desirable.

[0091] Also, as shown in Table 3, the joint bottom angle θ2 before bending is 0° for both the straight joint corresponding part 75 and the bent joint corresponding part 76. Although this joint bottom angle θ2 hardly changes for the straight joint corresponding part 75, it tilts upward by 1.2° after bending for the bent joint corresponding part 76. Since the desired joint bottom angle θ2 as the product shape is 0°, the change in the joint bottom angle θ2 is not desirable.

[0092] Also, as shown in Table 3, the connecting part angle θ3 before bending is 95.7° for both the straight joint corresponding part 75 and the bent joint corresponding part 76. However, it can be seen that by bending, θ3 hardly changes in the straight joint corresponding part 75, while it decreases to 93.1° in the bent joint corresponding part 76. Since the desired connecting part angle θ3 as the product shape is 95.7°, the change in the connecting part angle θ3 is not desirable.

[0093] Also, due to the changes in the tip angle θ1, the joint bottom angle θ2, and the connecting part angle θ3 described above, as shown in Table 3, the change amount of the opening width M in bending is 0.5 mm in the direction in which the opening width M opens in the straight joint corresponding part 75, and 1 mm ( - 1.0 mm in the table) in the direction in which the opening width M closes in the bent joint corresponding part 76, indicating that it fluctuates by bending. That is, it has changed from the value of the opening width M desired as the product shape, and there may be a case where a good joint shape cannot be obtained in the product.

[0094] As described above with reference to FIGS. 12 and 13 and Table 3, in bending forming, there is a problem that the shape of the joint corresponding portion changes, and as a result, a desired product shape cannot be obtained. Further, through such studies, the inventors of the present invention clarified the influence on the changes in the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M due to bending forming.

[0095] The inventors of the present invention have intensively verified to solve this problem. After considering the shape change of the joint corresponding portion in bending forming, it was confirmed that a desired joint shape can be obtained after bending forming by changing the shape of the joint corresponding portion in advance at a stage prior to bending forming. Specifically, in finish rolling, a process is performed in which the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 of the joint corresponding portion are bent at a predetermined angle to an angle different from the angle in the product shape. Further, a process is performed in which the opening width M of the joint corresponding portion is also changed to a length different from the length of the opening width in the product, so that a joint corresponding portion having a desired shape (that is, a substantially product shape) can be obtained after bending forming. Hereinafter, the pre-forming according to this modification will be described.

[0096] The pre-forming is performed, for example, in the finish rolling mill 19 before performing the bending forming in the bending forming machine 20. In the process of pre-bending the tip angle θ1 by a predetermined angle, the suitable bending angle is determined according to the angle change of the tip angle θ1 that occurs in the bending forming. Specifically, basically, an angle having the same magnitude as the angle change occurring in the tip angle θ1 during bending forming but with the opposite sign may be used as the predetermined angle to be pre-bent. That is, taking the case of Table 3 as an example, the angle change in the bending forming of the bent joint corresponding portion 76 is a change of -0.5° from 42° to 41.5°, and the angle change of the straight joint corresponding portion 75 is a change of 0.4° from 42° to 42.4°. Therefore, when it is desired to set the angle of the tip angle θ1 after bending forming to a desired angle, an angle change of 0.5° may be imparted in advance to the tip angle θ1 of the bent joint corresponding portion 76 with respect to the desired angle, and an angle change of -0.4° may be imparted in advance to the tip angle θ1 of the straight joint corresponding portion 75 with respect to the desired angle.

[0097] That is, when imparting an angular change to the tip angle θ1 by pre-forming, when an angular change occurs such that the angle decreases in bending, it is necessary to impart an angle such that θ1 is larger than the desired angle after bending in advance, and when an angular change occurs such that the angle increases, it is necessary to impart an angle such that θ1 is smaller than the desired angle after bending in advance. That is, in the case shown in Table 3 above, since the tip angle θ1 of the bend joint corresponding portion 76 decreases from 42° to 41.5°, it is necessary to impart an angular change that increases the tip angle θ1 in advance in the bend joint corresponding portion 76. On the other hand, since the tip angle θ1 of the straight joint corresponding portion 75 increases from 42° to 42.4°, it is necessary to impart an angular change that decreases the tip angle θ1 in advance in the straight joint corresponding portion 75. Regarding what kind of angular change is imparted in pre-forming, the same concept can be applied to the joint bottom angle θ2 and the connecting portion angle θ3.

[0098] Also, regarding the opening width M of the joint corresponding portion, when a process of changing it to a length different from the length of the opening width in the product is performed in advance before bending, the suitable length for the change is determined according to the length change of the opening width M that occurs in bending. Specifically, it is preferable to set a length that is substantially the same size as the length change that occurs in the opening width M during bending and has the opposite sign as the length to be changed in advance. That is, taking the case of Table 3 as an example, since the length change in the bending of the opening width M of the bend joint corresponding portion 76 is 1.0 mm in the direction in which the opening width M closes, when the opening width M after bending is desired to be a desired length, a length change of 1.0 mm in the opening direction may be imparted to the opening 75d in advance. On the other hand, since the length change in the bending of the opening width M of the straight joint corresponding portion 75 is 0.5 mm in the direction in which the opening width M opens, when the opening width M after bending is desired to be a desired length, a length change of 0.5 mm in the closing direction may be imparted to the opening 76d in advance.

[0099] When imparting a length change to the opening in advance, in the case where the opening width M decreases (narrows) in the bending process, a length change that makes the opening width M larger (wider) than the desired length after the bending process may be imparted in advance. On the other hand, in the case where the opening width M increases (widens) in the bending process, a length change that makes the opening width M smaller (narrows) than the desired length after the bending process may be imparted in advance. Of course, since the opening width M also changes when the values of the tip angle θ1, the joint bottom angle θ2, and the connecting part angle θ3 change, it is preferable to adjust the opening width M in combination with the change of the tip angle θ1, the joint bottom angle θ2, and the connecting part angle θ3 of the joint corresponding part.

[0100] Table 4 below shows the changes in the tip angle θ1, the joint bottom angle θ2, the connecting part angle θ3, and the opening width M in the bending process when the pre-forming according to this modification example is performed. Note that Table 4 was measured for the same joint corresponding part as shown in Table 3 above, and the tip angle in the desired product shape is 42°.

[0101]

Table 4

[0102] According to this modification example, as shown in Table 4, by changing the tip angle θ1, the joint bottom angle θ2, the connecting part angle θ3, and the opening width M by pre-forming, a desired joint shape can be obtained after the bending process. Therefore, it is possible to suppress the poor joint shape of the product associated with the angle change and the opening width change of the joint corresponding part, which is a problem in the manufacturing method of the steel sheet pile using the bending process of the Z-shaped steel sheet pile with a flat joint. Thus, a steel sheet pile product with a good joint shape can be efficiently manufactured.

[0103] Regarding the tip angle θ1 of the bent joint corresponding portion 76 and the joint bottom angle θ2 of the straight joint corresponding portion 75, in the bending machine, it may be dealt with by changing the groove shape according to the change in the same manner as in the above embodiment. FIG. 16 is a schematic explanatory view showing an example of the groove shape for changing the shape in response to the change in the tip angle θ1 of the bent joint corresponding portion 76 and the joint bottom angle θ2 of the straight joint corresponding portion 75 in the Z-shaped steel sheet pile. As shown in FIG. 16, a relief portion 90 may be provided in a portion of the groove roll of the bending machine that faces the bent joint corresponding portion 76 and the right arm corresponding portion 73. Further, a relief portion 91 may be provided in a portion that faces the straight joint corresponding portion 75 and the left arm corresponding portion 72. The shapes of the relief portions 90 and 91 are arbitrary. For example, in the groove roll, it may be configured in an arc shape having a predetermined radius of curvature outward from the middle of the portion facing the left arm corresponding portion 72 or the right arm corresponding portion 73.

[0104] The shapes of the relief portions 90 and 91 may be a straight line or a combination of a straight line and an arc other than an arc shape. For example, by relieving the straight joint corresponding portion 75 in the outer direction according to the change in the joint bottom angle θ2, the joint bottom angle θ2 can be formed into a desired angle. Note that the configuration provided with such relief portions 90 and 91 may be applied to at least one of each stand of the bending machine 20, and preferably, it may be applied to the final stand.

[0105] From the examination results in the above embodiment and the modified example, when performing bending forming to reduce the angle formed by the web corresponding portion and the flange corresponding portion, even if the cross-sectional shape changes, if reverse deformation of the same magnitude as the magnitude of the change caused by the bending forming is preformed on the material to be rolled by a finishing rolling machine or the like, it can be seen that a good joint shape can be obtained. That is, it is also applicable to the hat-shaped steel sheet pile having a flat joint as shown in FIG. 10(a). For example, when manufacturing a hat-shaped steel sheet pile having such a configuration in the U posture, the straight joint where the upper roll contacts the joint bottom surface portion and the bent joint where the joint tip portion contacts are deformed in the same manner as the joint of the Z-shaped steel sheet pile shown in FIG. 10(b). Therefore, the target product shape can be obtained by applying the preforming described in the first modified example. Hereinafter, the case where the technology of the present invention is applied to a hat-shaped steel sheet pile having a flat joint will be described as a second modified example.

[0106] (Second Modified Example) The hat-shaped steel sheet pile having the flat joint shown in Fig. 10(a) has joint corresponding parts similar to the straight joint corresponding part 75 and the bent joint corresponding part 76 described in the above first modified example, and its shape is as described above with reference to Figs. 12 and 13. Further, the bending of the hat-shaped steel sheet pile having the flat joint is performed by a bending machine equipped with upper and lower hole dies in the same manner as in the above embodiment. Therefore, the detailed description of the bending is omitted here.

[0107] In order to confirm that the tip angle θ1, the joint bottom angle θ2, the connecting part angle θ3, and the opening width M of the opening 75d change due to the bending during the manufacture of the hat-shaped steel sheet pile having the flat joint, and the joint shape changes from the desired shape, the inventors verified the respective values of the tip angle θ1, the joint bottom angle θ2, the connecting part angle θ3, and the opening width M during the bending. Note that the tip angle θ1 before the bending in this verification is 36.0°, the joint bottom angle θ2 is 0°, the connecting part angle θ3 is 100.5° for the bent joint, and 105.0° for the straight joint, and these values are the desired values in the hat-shaped steel sheet pile product having the flat joint.

[0108] Regarding the tip angle θ1 of the bent joint corresponding part 76 and the joint bottom angle θ2 of the straight joint corresponding part 75, similar to the first modified example, it may be dealt with by changing the hole die shape according to the changes in the tip angle θ1 and the joint bottom angle θ2 in the bending machine. Fig. 17 is a schematic explanatory view showing an example of the hole die shape for changing the shape in response to the changes in the tip angle θ1 and the joint bottom angle θ2 in the hat-shaped steel sheet pile having the flat joint. Fig. 17(a) is an explanatory view of the hole die shape corresponding to the bent joint corresponding part 76, and Fig. 17(b) is an explanatory view of the hole die shape corresponding to the straight joint corresponding part 75.

[0109] As shown in Fig. 17, in the pass roll of the bending machine, relief portions 93 and 94 may be provided in the same manner as in the above modification. Specifically, it may be configured in an arc shape having a predetermined radius of curvature outward from the middle of the portion facing the left arm corresponding portion 72, and the gap L2 between the bend joint corresponding portion 76 and the roll may be made larger than the gap L1 between the right arm corresponding portion 73 and the roll (i.e., L1 < L2). The shape of the relief portion 94 is arbitrary. For example, in the pass roll, it may be configured in an arc shape having a predetermined radius of curvature outward from the middle of the portion facing the left arm corresponding portion 72.

[0110] The shape of the relief portion 94 may be a straight line or a combination of a straight line and an arc other than an arc shape. By moving the straight joint corresponding portion 75 outward in response to the change in the joint bottom angle θ2, the joint bottom angle θ2 can be formed into a desired angle. Note that the configuration with such a relief portion 94 provided may be applied to at least one of each stand of the bending machine 20, and preferably, it may be applied to the final stand. Further, when providing the relief portion 94 in the pass roll of the bending machine 20, it is preferable not to perform the pre-forming regarding the joint bottom angle θ2 according to this modification.

[0111] Table 5 below shows the changes in the tip angle θ1, joint bottom angle θ2, connecting portion angle θ3, and opening width M in the bending forming when no pre-forming is performed for the straight joint corresponding portion 75 and the bend joint corresponding portion 76 of the hat-shaped steel sheet pile having a flat joint. Here, verification was performed for the case where 27° bending forming was performed by two stands. In this case, in both of the two-stand bending forming rolls in advance, the gap L2 between the bend joint corresponding portion 76 and the roll was made 1 mm larger than the gap L1 between the right arm corresponding portion 73 and the roll.

[0112]

Table 5

[0113] As shown in Table 5, the tip angle θ1 before bending forming is 36.0° for both the straight joint corresponding part 75 and the bent joint corresponding part 76. However, it can be seen that by bending forming, the tip angle θ1 increases to 38.2° at the straight joint corresponding part 75 and decreases to 32.2° at the bent joint corresponding part 76. Since the desired tip angle θ1 as the product shape is 36.0°, the shape change of the joint corresponding part leads to deterioration of the product shape, which is not desirable.

[0114] Also, as shown in Table 5, the joint bottom angle θ2 before bending forming is 0° for both the straight joint corresponding part 75 and the bent joint corresponding part 76. This joint bottom angle θ2 is inclined by -1.0° after bending forming for the straight joint corresponding part 75 and inclined by -0.8° after bending forming for the bent joint corresponding part 76. Since the desired joint bottom angle θ2 as the product shape is 0°, the change of the joint bottom angle θ2 is not desirable.

[0115] Also, as shown in Table 5, the connecting part angle θ3 before bending forming is 105.0° for the straight joint corresponding part 75 and 100.5° for the bent joint corresponding part 76. However, it can be seen that by bending forming, although θ3 hardly changes at the straight joint corresponding part 75, θ3 increases to 101.2° at the bent joint corresponding part 76. The desired connecting part angle θ3 as the product shape is 105.0° for the straight joint corresponding part 75 and 100.5° for the bent joint corresponding part 76, and the change of the connecting part angle θ3 is not desirable.

[0116] Also, due to the changes in the tip angle θ1, the joint bottom angle θ2, and the connecting part angle θ3, as shown in Table 5, the change amount of the opening width M in bending forming is 1.2 mm in the opening direction of the opening width M at the straight joint corresponding part 75 and 1 mm ( -1.0 mm in the table) in the closing direction of the opening width M at the bent joint corresponding part 76, indicating that it fluctuates by bending forming. That is, it has changed from the value of the opening width M desired as the product shape, and there may be a case where a good joint shape cannot be obtained in the product.

[0117] Similar to the above-described Modification Example 1, after considering the shape change of the joint corresponding portion in the bending forming, it was confirmed that by changing the shape of the joint corresponding portion in advance in the stage prior to the bending forming, a desired joint shape can be obtained after the bending forming. In addition, it was confirmed that by changing the shape of the upper hole die roll facing the straight joint corresponding portion 75 in the bending forming, a desired joint shape can be obtained after the bending forming.

[0118] Specifically, in the finish rolling, a process is performed in which the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 of the joint corresponding portion are bent to angles different from the angles in the product shape, and also a process is performed in which the opening width M of the joint corresponding portion is changed to a length different from the length of the opening width in the product. As a result, a joint corresponding portion having a desired shape (i.e., substantially the product shape) can be obtained after the bending forming. Further, with respect to the joint bottom angle θ2 of the straight joint corresponding portion 75, a relief portion (see the relief portion 94 in FIG. 17) is provided in the hole die roll of the bending forming machine so as to cancel the change from the desired angle, whereby a joint corresponding portion having a desired shape can be obtained. Hereinafter, the pre-forming according to this modification example will be described.

[0119] Table 6 below shows the changes in the tip angle θ1, the joint bottom angle θ2, the connecting portion angle θ3, and the opening width M in the bending forming when the pre-forming according to this modification example is performed. Note that Table 6 was measured for the same joint corresponding portion as that shown in Table 5 above.

[0120]

Table 6

[0121] According to this modification, as shown in Table 6, by changing the tip angle θ1, the joint bottom angle θ2, the connecting part angle θ3, and the opening width M by pre-forming, a desired joint shape can be obtained after bending. In particular, compared with the normal hat-shaped steel sheet pile described in the above embodiment, changes were observed in the joint bottom angle θ2 of the straight joint corresponding part 75 and the connecting part angle θ3 during bending. Therefore, in this modification, an angular change of -1.0° was given as pre-forming to θ3 in the bent joint. In addition, in the upper die roll 50 of the bending machine 20, a relief part (see Fig. 17(b)) with an arc of a radius of curvature of 3000 mm was added from the middle of the left arm corresponding part 65 to the part facing the joint bottom surface 75b of the straight joint corresponding part 75.

[0122] By performing pre-forming as shown in Table 6, it is possible to suppress the defective joint shape of the product associated with the angular change and the opening width change of the joint corresponding part, which are problems in the manufacturing method of the steel sheet pile using the bending of the hat-shaped steel sheet pile with a flat joint, and it is possible to efficiently manufacture a steel sheet pile product with a good joint shape.

Example

[0123] (Example 1) As Example 1 of the present invention, bending was performed by using a bending machine hot-rolled according to the manufacturing method of the hat-shaped steel sheet pile described in the above embodiment, and a simulation analysis was performed on the deformation of the material to be rolled during bending. The hat-shaped steel sheet pile product to be manufactured was a 900 mm wide hat-shaped steel sheet pile with a second moment of area of 45000 cm 4 . The conditions and results of this simulation analysis are also shown in Tables 1 and 2 referred to in the above embodiment, and here, Tables 1 and 2 above are cited for explanation.

[0124] First, after finishing the material to be rolled to the desired product thickness and joint shape by finish rolling, bending with a flange angle change of 29° was performed using a two-stunt bending machine. As a result, it was found that the deformation of each part of the joint as shown in Table 1 above occurred.

[0125] Therefore, for the same rolled material, pre-forming was carried out under the conditions shown in Table 2 above in finish rolling, and bending was carried out under the same conditions. As a result, as shown in Table 2, it was found that the joint shape as intended was obtained.

[0126] Note that the pre-forming amount may be determined based on the results of simulation analysis as in Example 1, or alternatively, tests may be conducted on an actual machine (actual rolling and bending equipment), and the amount of deformation associated with bending may be calculated from a comparison of the shape of the rolled material and the joint shape before and after finish rolling and bending, and the pass design for finish rolling may be modified. Also, here, the tip angle θ1, joint bottom angle θ2, connecting part angle θ3, and opening width M of the product manufactured by bending are each shown as constant values. However, in reality, the tip angle θ1, joint bottom angle θ2, connecting part angle θ3, and opening width M of the product manufactured by bending vary slightly in the longitudinal direction, and the amount of change in the tip angle θ1, joint bottom angle θ2, connecting part angle θ3, and opening width M caused by bending also varies slightly in the longitudinal direction. Therefore, these values may be determined based on, for example, the respective average values within a predetermined range.

[0127] (Example 2) As Example 2 of the present invention, bending was carried out using a hot bending machine by the method for manufacturing a Z-shaped steel sheet pile described in the above modification example, and a simulation analysis was performed on the deformation of the rolled material in bending. The Z-shaped steel sheet pile product to be manufactured was a Z-shaped steel sheet pile having a hat-shaped cross section corresponding to a section modulus of 5200 cm 3 / m and a width of 1400 mm in a butted state of two sheets. Note that the conditions and results of this simulation analysis are also shown in Tables 3 and 4 referred to in the above modification example, and here, Tables 3 and 4 above are cited for explanation.

[0128] The angular change pre-applied to the tip angle θ1 is desirably of the same magnitude as the angular change occurring during bending and of the opposite sign. Therefore, in the straight joint corresponding portion 75, an angular change of -0.5° is pre-applied to the tip angle θ1, and in the bent joint corresponding portion 76, an angular change of 0.5° is pre-applied to the tip angle θ1. Specifically, the tip angle θ1 of the straight joint corresponding portion 75 is set to 41.5° (42° - 0.5°) in advance, and the tip angle θ1 of the bent joint corresponding portion 76 is set to 42.5° (42° + 0.5°) in advance.

[0129] As shown in Table 4, when bending is performed with the angular change pre-applied and the tip angle θ1 of the straight joint corresponding portion 75 being 41.5° and the tip angle θ1 of the bent joint corresponding portion 76 being 42.5°, after bending, the tip angle θ1 of both the straight joint corresponding portion 75 and the bent joint corresponding portion 76 becomes the desired angle of approximately 42° (strictly 41.9°, 42.0°). That is, it was found that by applying and changing the angle by giving the predetermined angle measured in advance as shown in Table 3 to the tip angle θ1 of the joint corresponding portion before bending, the tip angle θ1 of the joint corresponding portion after bending can be made the desired angle.

[0130] Also, in the straight joint corresponding portion 75, no pre-angular change was applied to the joint bottom angle θ2, and in the bent joint corresponding portion 76, a pre-angular change of -1.0° was applied to the joint bottom angle θ2. By performing bending from this state, it was found that after bending, both the straight joint corresponding portion 75 and the bent joint corresponding portion 76 become approximately 0° (strictly 0.1°, 0.2°), and the desired joint bottom angle θ2 can be obtained.

[0131] Also, in the straight joint corresponding portion 75, no pre-angular change was applied to the connecting portion angle θ3 in advance, and in the bent joint corresponding portion 76, a pre-angular change of 2.5° was applied. By performing bending from this state, it was found that after bending, both the straight joint corresponding portion 75 and the bent joint corresponding portion 76 become 95.6°, and generally the desired connecting portion angle θ3 can be obtained.

[0132] Also, as described above, it is desirable that the length change pre-applied to the opening is approximately the same magnitude as the length change of the opening width that occurs during bending, and has the opposite sign. Therefore, a length change of 0.5 mm in the closing direction is pre-applied to the opening width M of the straight joint corresponding portion 75, and a length change of 1.0 mm in the opening direction is pre-applied to the opening width M of the bent joint corresponding portion 76. Note that the change amount of this opening width M is the amount including the change of the opening width M due to the adjustment amounts of θ1 to θ3 described above.

[0133] By changing the opening widths M of the openings 75d and 76d in advance, reducing the opening width M of the straight joint corresponding portion 75 by 0.5 mm, and increasing the opening width M of the bent joint corresponding portion 76 by 1.0 mm, and then performing bending, the opening width M of the opening of the bent joint corresponding portion 76 also becomes approximately the desired width after bending. That is, it was confirmed that by pre-applying an opening width change of a predetermined length measured in advance to the joint corresponding portion, the opening width of the joint corresponding portion after bending can be made the desired length. From the above results, it was confirmed that a Z-shaped steel sheet pile product with high dimensional accuracy can be manufactured by the manufacturing method of the Z-shaped steel sheet pile according to the present embodiment. Of course, the adjustment of the opening width M may be performed by changing any one or two or more of the tip angle θ1, the joint bottom angle θ2, and the connecting portion angle θ3 as described above.

Industrial Applicability

[0134] The present invention can be applied to a method for manufacturing steel sheet piles.

Explanation of Signs

[0135] 10… Rough rolling mill 13… First intermediate rolling mill 14… Edger rolling mill 16… Second intermediate rolling mill 17… Edger rolling mill 19… Finishing rolling mill 19a… Finishing material 20… Bending forming device 22… First stand 23… Second stand 40… Upper pass roll 41…Lower pass roll 44…Housing 45…Pass 50…Upper pass roll 51…Lower pass roll 54…Housing 55…Pass 60…Web corresponding part 62, 63…Flange corresponding part 65, 66…Arm corresponding part 68, 69…Joint corresponding part 68a, 69a…Joint connecting part 68b, 69b…Bottom part of joint 68c, 69c…Tip part of joint 68d, 69d…Opening 70, 71…Corner part 72…Left arm corresponding part (of Z-shaped steel sheet pile) 73…Right arm corresponding part (of Z-shaped steel sheet pile) 75…Straight joint corresponding part 76…Bent joint corresponding part 77…Flange corresponding part (of Z-shaped steel sheet pile) θ1…Tip angle θ2…Bottom angle of joint θ3…Angle of connecting part M…Opening width L…Rolling line

Claims

1. A method for manufacturing a steel sheet pile, which has at least a flange corresponding part, an arm corresponding part connected to one or both ends of the flange corresponding part, and a joint corresponding part connected to the tip of the arm corresponding part, and which performs rough rolling, intermediate rolling, and finish rolling by hot rolling on the material to be rolled, and then performs bending forming hot, wherein: In the finish rolling, which is the stage before the bending forming, pre-forming is performed to change the shape of the joint corresponding part to a shape different from that of the product. In the pre-forming of the shape of the joint corresponding part, for at least one or more of the dimensions of the angle θ1 formed between the tip part and the bottom part of the joint corresponding part, the angle θ2 formed between a reference plane parallel to the arm corresponding part and the bottom part of the joint corresponding part, the angle θ3 formed between the connecting part of the arm corresponding part and the joint corresponding part and the bottom part of the joint corresponding part, and the width M of the opening of the joint corresponding part. At least one or more of the following pre-formings (1) to (4) are performed. In the bending forming, at least at the corner part, which is the boundary between the flange corresponding part and the arm corresponding part, bending is applied by upper and lower pass rolls so as to reduce the angle formed between the flange corresponding part and the arm corresponding part. A method for manufacturing a steel sheet pile. (1) The angle θ1 formed between the tip part and the bottom part of the joint corresponding part is set to a state bent to a predetermined angle θ1-1 determined in advance based on the angle change caused by the bending forming. (2) The angle θ2 formed between a reference plane parallel to the arm corresponding part and the bottom part of the joint corresponding part is set to a state bent to a predetermined angle θ2-1 determined in advance based on the angle change caused by the bending forming. (3) The angle θ3 formed between the connecting part of the arm corresponding part and the joint corresponding part and the bottom part of the joint corresponding part is set to a state bent to a predetermined angle θ3-1 determined in advance based on the angle change caused by the bending forming. (4) The width M of the opening of the joint corresponding part is set to a predetermined length M1, which is a value determined in advance based on the length change caused by the bending forming.

2. The method for manufacturing a steel sheet pile according to claim 1, wherein in the pre-forming of the shape of the joint corresponding part, at least one or more of the following pre-formings (1) to (4) are performed on at least one or more of the dimensions of the angle θ1 formed between the tip part and the bottom part of the joint corresponding part and the width M of the opening of the joint corresponding part. Pre-forming to make the angle θ1 at the joint corresponding part where the roll contacts the tip part larger than that of the product Pre-forming to make the angle θ1 at the joint corresponding part where the roll contacts the bottom part smaller than that of the product Pre-forming to make the width M of the opening at the joint corresponding part where the roll contacts the tip part larger than that of the product Pre-forming to make the width M of the opening at the joint corresponding part where the roll contacts the bottom part smaller than that of the product

3. The predetermined angles θ1-1, θ2-1, θ3-1 in the state where the pre-forming of (1) to (3) is performed are angles obtained by adding a value with the same magnitude but opposite sign to the change in the angles θ1, θ2, θ3 caused by the bending forming, with respect to the angles θ1-2, θ2-2, θ3-2 which are the angles corresponding to the angles θ1-1, θ2-1, θ3-1 in the desired product shape, The predetermined length M1 of the opening in the state where the pre-forming of (4) is performed is a length obtained by adding a value with the same magnitude but opposite sign to the change in the width M of the opening caused by the bending forming, with respect to the length M2 of the opening in the desired product shape. The manufacturing method of the steel sheet pile according to claim 1 is characterized in that.

4. The predetermined angles θ1-1, θ2-1, θ3-1 in the pre-forming of (1) to (3), and the predetermined length M1 in the pre-forming of (4) are based on at least one or more parameter changes of the following (5) to (8). The manufacturing method of the steel sheet pile according to claim 1 is characterized in that. (5) The change in the angle θ1 formed between the tip part and the bottom part of the joint corresponding part caused by the bending forming (6) The change in the angle θ2 formed between the reference plane parallel to the arm corresponding part and the bottom part of the joint corresponding part caused by the bending forming (7) The change in the angle θ3 formed between the connecting part between the arm corresponding part and the joint corresponding part and the bottom part of the joint corresponding part caused by the bending forming (8) The change in the width M of the opening of the joint corresponding part caused by the bending forming

5. The hole-type roll of the bending forming machine for performing the bending forming is provided with a relief part at a portion facing the joint corresponding part on the upper claw side and / or the lower claw side. The manufacturing method of the steel sheet pile according to any one of claims 1 to 4 is characterized in that. **Claim 6**: The steel sheet pile is a hat-shaped steel sheet pile. In the bending forming, bending is applied by upper and lower pass rolls so as to reduce the angle formed between the web corresponding portion and the flange corresponding portion of the material to be rolled at the corner portion which is the boundary between the web corresponding portion and the flange corresponding portion of the material to be rolled. The method for manufacturing a steel sheet pile according to any one of claims 1 to 5. **Claim 7**: The bending forming is characterized in that the angles formed between the flange corresponding portion and the web corresponding portion, and between the flange corresponding portion and the arm corresponding portion of the material to be rolled are changed, and bending forming is performed so as to increase the height of the material to be rolled to a desired product height. The method for manufacturing a steel sheet pile according to claim 6. **Claim 8**: The steel sheet pile is a Z-shaped steel sheet pile. The method for manufacturing a steel sheet pile according to any one of claims 1 to 5. **Claim 9**: The bending forming is characterized in that the angle formed between the flange corresponding portion and the arm corresponding portion of the material to be rolled is changed, and bending forming is performed so as to increase the height of the material to be rolled to a desired product height. The method for manufacturing a steel sheet pile according to claim 8.

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