Steel sheet pile manufacturing method and manufacturing device

Abstract

To provide a method for producing a steel sheet pile which suppresses a forming load and the deterioration of material quality during bending, and reduces spring back after forming, thereby being able to produce the steel sheet pile with high production efficiency.SOLUTION: In a method for producing a steel sheet pile, a material to be rolled is subjected to rough rolling, intermediate rolling, and finish rolling by hot rolling, and is then subjected to bending. The rolled material after the finish rolling at least includes: a web corresponding part; two flange corresponding parts which have one end parts connected to both end parts of the web corresponding part, and which each have a wider angle than a finished product; and corner parts which are connection parts between the web corresponding part and the respective flange corresponding parts. In the bending, upper and lower grooved rolls are used. In a hot state, the upper and lower grooved rolls are partly brought into contact with the insides of the corner parts, thereby bending the corner parts.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing steel sheet piles such as hat-shaped steel sheet piles and U-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 and U-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 sequentially rolled by a roughing mill, an intermediate rolling mill, and a finishing rolling mill equipped with a pass.

[0003] In particular, when manufacturing large and asymmetric products such as hat-shaped steel sheet piles, in order to manufacture them using the above-mentioned roughing 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 variations and defects in the shape of the product 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 to manufacture a steel sheet pile with a width wider than that of the rolling equipment and a steel sheet pile with a high cross-sectional height. In addition, as shown in Patent Document 3, a technique is known in which the rolling process and the bending process are separated, and a universal mill and a two-high mill are used in the bending process.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

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 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 to be rolled, and there is a problem that the elongation length of the product is small. In addition, 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 a large steel sheet pile product 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. There is also a problem that the friction between the material to be rolled and the roll becomes strong due to an increase in the peripheral speed difference between the rolls, resulting in scratches.

[0006] In addition, in the manufacturing method of steel sheet piles as exemplified in Patent Document 2 above, bending is performed by cold working, and since the corner portion of the material to be rolled is not directly pressed down using a support 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 tends to be large because it is cold working. Also, when forming the web and flange at different timings with a plurality of forming rolls (support rolls), there is a problem that the bending forming efficiency decreases because the fulcrum shifts in the longitudinal direction of the material to be rolled.

[0007] In addition, in the manufacturing method of steel sheet piles 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, the processing load is large, and problems such as deterioration of the material such as a decrease in elongation and toughness and an increase in residual stress may occur. 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 a complication of the structure.

[0008] In addition, Patent Document 3 discloses a technique in which a material is linearly rolled to a predetermined thickness and a joint claw is formed, and then bending is performed to obtain a predetermined shape. In this technique, large bending of the flange is performed using the vertical roll of a universal rolling mill, which requires a large and complex mechanism mill. Also, in order to manufacture a product from a linearly shaped material to be rolled, multiple mills are required in the bending process. Further, since the shape of the material to be rolled after rolling is linear, when there is a large thickness difference depending on the part as in a general hot-rolled steel sheet pile, the distribution of the reduction ratio in the width direction becomes large in the rolling process, making it difficult to apply such a product. Moreover, when manufacturing a large steel sheet pile product, in the technique of Patent Document 3, the width of the material to be rolled in the rolling process becomes too large, resulting in poor manufacturing efficiency.

[0009] In addition, in the technique of Patent Document 3, it is difficult to accommodate the sheet thickness distribution and tolerance of the material to be rolled in the previous rolling process. When such sheet thickness distribution and tolerance of the material to be rolled occur, the subsequent bending process becomes difficult. Also, when bending from a flat state, it is difficult to correct abnormalities such as offset during biting in the bending process.

[0010] Therefore, in view of the above problems, an object of the present invention is to provide a method and apparatus for manufacturing a steel sheet pile that can suppress the forming load (load and torque) and material deterioration during bending, reduce springback after forming, and manufacture a large steel sheet pile with high manufacturing efficiency.

Means for Solving the Problems

[0011] To achieve the above object, according to the present invention, there is provided a method for manufacturing a steel sheet pile in which rough rolling, intermediate rolling, and finish rolling are performed on a material to be rolled by hot rolling, and then bending forming is performed. After the finish rolling, the material to be rolled includes at least a web corresponding portion, two flange corresponding portions each having one end connected to both ends of the web corresponding portion and having an angle extending wider than the product, and a corner portion that is a connecting portion between the web corresponding portion and each of the flange corresponding portions. In the bending forming,The roll gaps of the portions of the upper and lower profiled rolls that face the web corresponding portion and the flange corresponding portion are configured to be larger than the thicknesses of the web corresponding portion and the flange corresponding portion, respectively. Using an upper and lower pass roll, a part of the upper and lower pass roll is brought into contact with the inside of the corner portion during hot working to bend the corner portion. bringing a part of the upper and lower profiled rolls into contact with the other end or the vicinity thereof of the flange corresponding portion There is provided a method for manufacturing a steel sheet pile, characterized by the above. Here, hot working means the temperature before the transformation of the material to be rolled is completed after hot rolling.

[0012] In the bending forming, the upper and lower pass roll may be brought into contact so that a force is applied to the other end or the vicinity thereof of the flange corresponding portion in a direction that balances the force applied with the contact of the upper and lower pass roll with the corner portion.

[0014] Corresponding to the changes in the thickness of the web corresponding portion and the flange corresponding portion, the roll gaps of the portions of the upper and lower pass roll facing the web corresponding portion and the flange corresponding portion may be set to be larger than the respective thicknesses.

[0015] In the hot rolling, the material to be rolled is rolled so that the plate thickness of the corner portion is thicker than the product plate thickness, and in the bending forming, the corner portion may be pressed down by the upper and lower pass roll.

[0016] In the bending forming, only one of the upper and lower pass rolls may be driven.

[0017] In the bending forming, the contact portion between the material to be rolled and the upper and lower pass roll may be lubricated.

[0018] The bending forming machine that performs the bending forming and the finishing rolling machine that performs the finishing rolling may be tandem.

[0019] The rolled material after the finish rolling is provided with an arm corresponding portion that connects to the other end of the flange corresponding portion, and the upper and lower pass rolls may be brought into contact with a part of the upper and lower pass rolls inside the corner portion to bend the corner portion, and the upper and lower pass rolls may be brought into contact with another corner portion that is a connection portion between the flange corresponding portion and the arm corresponding portion so that a force is applied in a direction that balances with the force applied due to the contact of the upper and lower pass rolls with the corner portion.

[0020] In the bending forming, a pass roll facing the web corresponding portion may be brought into contact with the outside of the web corresponding portion, and a pass roll facing the arm corresponding portion may be brought into contact with the outer surface of the arm corresponding portion.

[0021] The rolled material after the finish rolling is provided with a joint corresponding portion formed at the tip of the arm corresponding portion, and in the bending forming, a pass roll facing the joint corresponding portion may be brought into contact with the outer surface of the joint corresponding portion so that the joint corresponding portion becomes substantially horizontal.

[0022] In the hot rolling, the rolled material may be rolled so that the plate thickness of the other corner portion becomes thicker than the product plate thickness, and in the bending forming, the other corner portion may be pressed down by the upper and lower pass rolls.

[0023] The steel sheet pile may be a hat-shaped steel sheet pile.

[0024] The rolled material after the finish rolling is provided with a joint corresponding portion formed at the tip of the flange corresponding portion, and in the bending forming, a pass roll facing the joint corresponding portion may be brought into contact with the outer surface of the joint corresponding portion so that the joint corresponding portion becomes substantially horizontal.

[0025] The steel sheet pile may be a U-shaped steel sheet pile.

[0026] According to another aspect of the present invention, there is provided a manufacturing apparatus for steel roof sheets, which has a bending machine for performing bending after rough rolling, intermediate rolling, and finish rolling on a material to be rolled by hot rolling. After the finish rolling, the material to be rolled includes at least a web corresponding portion, two flange corresponding portions each having one end connected to both ends of the web corresponding portion and having an angle extending wider than the product, and a corner portion which is a connecting portion between the web corresponding portion and each of the flange corresponding portions. The bending machine has upper and lower pass rolls, and bends the corner portion hot using the upper and lower pass rolls. The roll gaps of the portions of the upper and lower profiled rolls that face the web corresponding portion and the flange corresponding portion are configured to be larger than the thicknesses of the web corresponding portion and the flange corresponding portion, respectively, during bending. The bending machine is configured to bend the corner portion by bringing a part of the upper and lower profiled rolls into contact with the inside of the corner portion while hot using the upper and lower profiled rolls, and bringing a part of the upper and lower profiled rolls into contact with the other end or the vicinity thereof of the flange corresponding portion. There is provided a manufacturing apparatus for steel roof sheets, characterized by the above.

[0027] The upper and lower pass rolls may have a shape such that when a part of the upper and lower pass rolls contacts the inside of the corner portion, a force is applied to the other end or the vicinity of the other end of the flange corresponding portion in a direction that balances the force applied with the contact.

[0029] Corresponding to changes in the thickness of the web corresponding portion and the flange corresponding portion, the roll gaps of the portions of the upper and lower pass rolls facing the web corresponding portion and the flange corresponding portion may be set to be larger than each thickness.

Advantages of the Invention

[0030] According to the present invention, it is possible to suppress the forming load and material deterioration during bending, reduce the springback after forming, and manufacture large steel roof sheets with high production efficiency.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification and the drawings, for components having substantially the same functional configuration, the same reference numerals are given and redundant description is omitted. In this embodiment, the case of manufacturing a hat-shaped steel sheet pile as a steel sheet pile product will be described.

[0033] 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 on 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 by 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 described by a dashed-dotted line.

[0034] As shown in FIG. 1, on the rolling line L, 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 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.

[0035] 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 the final product. Hereinafter, for the sake of explanation, the material to be rolled rolled by the rough rolling mill 10 is also referred to as a rough-shaped material, the material to be rolled rolled by the first intermediate rolling mill 13 to the second intermediate rolling mill 16 is also referred to as an intermediate material, and the material to be rolled rolled by the finishing rolling mill 19 is also referred to as a finishing material 19a. That is, the one 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).

[0036] 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 accordingly are general facilities conventionally used in the manufacture of steel sheet piles, the description of the detailed device configuration and the like is omitted in this specification.

[0037] Next, the detailed configuration of the bending machine 20 will be described with reference to the drawings. FIG. 2 is a schematic side cross-sectional view of the bending machine 20, and FIG. 3 is a schematic front view of the bending machine 20. The bending machine 20 shown in FIGS. 2 and 3 bends (bending forming) the finished material 19a finish-rolled by the finish rolling machine 19. Note that FIG. 3 shows a schematic front view of the first stand 22 included in the bending machine 20 described below. Here, in the present embodiment, the case where the bending machine 20 is composed of two forming stands (the forming stands 22 and 23 described below) is illustrated and described, but the bending machine 20 may be composed of a single stand or any plurality of stands.

[0038] As shown in FIG. 2, the bending 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 die holes (die holes 45 and 55 described later) composed of an upper die roll and a lower die roll are engraved in each of the stands 22 and 23, and the die hole shapes are different between the first stand 22 and the second stand 23.

[0039] Here, the roll configuration and die hole shape of the first stand 22 and the second stand 23 will be described. FIG. 4 is a schematic enlarged front view showing the die hole shape of the first stand 22, and FIG. 5 is a schematic enlarged front view showing the die hole shape of the second stand 23. Note that FIG. 4 shows the cross-sectional shape of the finished material 19a in a state before forming by the bending machine 20 with a dashed line, and FIG. 5 shows the cross-sectional shape of the finished material 19a' in a state before forming by the second stand 23 with a dashed line. Further, hereinafter, the case where a rolled material having a substantially hat shape is bent and formed in an upward-opening posture (with the web corresponding portion described later downward and the arm corresponding portion upward) will be illustrated and described.

[0040] As shown in FIGS. 3 and 4, an upper pass roll 40 and a lower pass roll 41 are supported by a housing 44 on the first stand 22, 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 a shape one step before the 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 finishing material 19a (i.e., the flange corresponding portion), the portion corresponding to the web of the finishing material 19a (i.e., the web corresponding portion), and the portion corresponding to the arm of the finishing material 19a (i.e., the arm corresponding portion), respectively, and bends the height and width of the finishing 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 shape - finishing material 19a) is rolled in the rough rolling mill 10 to the finishing rolling mill 19 with a shape having a low height, and a bending process is performed in the bending forming machine 20 to increase the height of the rolled material to the desired product height. This enables the production of large-sized hat-shaped steel sheet pile products.

[0041] Also, as shown in FIG. 5, an upper pass roll 50 and a lower pass roll 51 are supported by a housing 54 on the second stand 23, and a pass 55 is formed by the upper pass roll 50 and the lower pass roll 51. The 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 forming machine 20 (i.e., the flange corresponding portion), 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, a forming process 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.

[0042] Here, the roll gaps in the above-mentioned hole dies 45 and 55 during bending (the roll gap between the upper hole die roll 40 and the lower hole die roll 41 and the roll gap between the upper hole die roll 50 and the lower hole die 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, the thickness reduction of the finishing material 19a is not performed, and the hole die rolls of the first stand 22 and the second stand 23 and the finishing material 19a are configured to be in contact and perform bending only at some predetermined locations described later.

[0043] Also, as described later, during bending, the hole die rolls of the first stand 22 and the second stand 23 and the finishing material 19a may be subjected to pressing in addition to contact at some predetermined locations. In this specification, "contact" means a state in which only one of the upper surface or the lower surface of a specific location of the finishing material 19a abuts against the peripheral surface of the hole die roll in the bending machine 20. On the other hand, "pressing" means a state in which both the upper surface and the lower surface of a specific location of the finishing material 19a abut against the hole die roll and a force is applied to reduce the thickness in the bending machine 20.

[0044] For example, it is preferable that the above-mentioned roll gaps in the web corresponding portion and the portion facing the flange corresponding portion are about 0.5 mm to 3 mm larger than the thicknesses of the flange corresponding portion and the web corresponding portion of the finishing material 19a. In addition, also at the locations where the finishing material 19a in the arm corresponding portion in the above-mentioned hole dies 45 and 55 is applied, the roll gap may be configured to be larger than the thickness of the arm corresponding portion over the entire cross section. When the allowance range of the above-mentioned roll gap is smaller than 0.5 mm, there is a possibility that the load on the bending machine 20 increases due to the thickness reduction caused by the variation in the plate thickness of the finishing material 19a, and when it is larger than 3 mm, there is a possibility that the inclination angle of the flange corresponding portion cannot be formed into the target angle.

[0045] Here, the inventors conducted a more detailed examination of the allowance range of the roll gap at the web corresponding portion and the portion facing the flange corresponding portion, as well as the forming machine load characteristics (changes in load and torque) and formability (accuracy of bending angle). FIG. 10 is a graph showing the relationship between the "roll gap - material thickness (i.e., the allowance value of the roll gap)" during the bending forming of the finishing material 19a and the "load, torque" applied to the bending forming machine 20. Further, FIG. 11 is a graph showing the relationship between the "roll gap - material thickness (i.e., the allowance value of the roll gap)" during the bending forming of the finishing material 19a and the "angle between the web and the flange" after bending forming.

[0046] Note that the graphs in FIGS. 10 and 11 show the case where the dimensional conditions are such that the finishing material 19a after finish rolling has a substantially hat-shaped steel sheet shape with a width of 1400 mm, a web thickness of 14.7 mm, a flange thickness of 11.4 mm, and a flange angle of 40° (web-flange angle of 140°), and is bent and formed at the first stand 22 with a target flange angle of 56° (web-flange angle of 124°). FIG. 12 is a schematic explanatory diagram showing the dimensional relationship during the bending forming at the first stand 22. The examination here was carried out by taking the values of "T1 - t1", "T2 - t2", and "T3 - t3", which are the differences between the roll gaps T1, T2, T3 at each of the web corresponding portion, flange corresponding portion, and arm corresponding portion shown in FIG. 12 and the thicknesses t1, t2, t3 of the finishing material 19a at each location, as the allowance values of the roll gap.

[0047] As shown in FIG. 10, when the allowance value of the roll gap is 0.5 mm or more during bending forming, the changes in load and torque are gentle. On the other hand, when the allowance value of the roll gap is less than 0.5 mm, especially less than 0.2 mm, the increase rates of load and torque become large, and the increase at 0 mm or less (i.e., thickness reduction) is remarkable. From this result, it can be seen that in order to keep the forming load (load and torque) of the bending forming machine 20 low, it is preferable to set the allowance value of the roll gap to 0.5 mm or more considering the actual thickness variation.

[0048] Also, as shown in Fig. 11, if the allowance value of the roll gap is 0.5 mm to 3 mm during bending forming, the bending forming can be carried out at approximately the desired target angle (i.e., about 124° ± 1° which is the target web-flange angle). On the other hand, when the allowance value of the roll gap exceeds 3 mm, the pushing-in by the pass roll becomes smaller, the bending becomes weaker, and the web-flange angle tends to become larger than the target value. Therefore, in some cases, a large correction of the flange angle is required in the finishing process after bending forming. That is, particularly in the final stand, it is preferable that the upper limit of the allowance value of the roll gap is 3 mm.

[0049] Subsequently, 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 from the connecting side with the web corresponding portion in each of the flange corresponding portions 62 and 63 via corner portions 71, 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 product thickness by rolling in the finishing rolling mill 19, and the shapes of the joint corresponding portions 68 and 69 also have substantially the product joint shape.

[0050] Here, the plate thickness of the corner portion 70 (hereinafter also referred to as the web-flange corner portion 70) may be dimensionally designed to be thicker than the product plate thickness. The plate thickness of the web-flange corner portion 70 can be rolled to a desired plate thickness according to the rolling conditions and rolling design in hot rolling performed by the rough rolling mill 10, the first intermediate rolling mill 13, the second intermediate rolling mill 16, the finishing rolling mill 19, etc. (see Fig. 1).

[0051] Similarly, the thickness of the corner portion 71 (hereinafter also referred to as the flange-arm corner portion 71) may be dimensioned to be thicker than the product thickness. The thickness of the flange-arm corner portion 71 can be rolled to a desired thickness according to the rolling conditions and rolling design in hot rolling performed by the roughing mill 10, the first intermediate rolling mill 13, the second intermediate rolling mill 16, the finishing mill 19, etc. (see FIG. 1).

[0052] The finished material 19a shown in FIG. 6(a) is bent and formed so that the angle α formed by the web corresponding portion 60 and the flange corresponding portions 62, 63 in the pass 45 of the first stand 22 becomes smaller (becomes the angle α1 shown in FIG. 6(b)), and has a desired height as shown in FIG. 6(b). That is, in the first stand 22, bending is performed so that the height of the finished material 19a increases.

[0053] Next, as shown in FIG. 6(c), in the pass 55 of the second stand 23, the finished material 19a is bent and formed into a substantially product shape.

[0054] FIG. 7 is an explanatory diagram of the contact portions of the finished material 19a in the bending machine 20, and (a) to (d) each show an example of a contact portion. In FIG. 7, the contact portions are shown by thick lines. In the pass 45 of the first stand 22 and the pass 55 of the second stand 23, each pass roll and the finished material 19a are in contact only at a predetermined part of a part, and no reduction in thickness is performed. Specific contact portions between the pass roll and the finished material 19a are, for example, the inner corners 70a, 70b of the corner at the boundary between the web corresponding portion 60 and the flange corresponding portions 62, 63, and the inner corners 71a, 71b of the corner at the boundary between the flange corresponding portions 62, 63 and the arm corresponding portions 65, 66, as shown in FIG. 7(a). Here, "contact" means that at least the material and the pass roll are in contact, and a state where a force for pressing the material is further applied may also be acceptable.

[0055] As shown in Fig. 7(a), the contact points 70a and 70b are inside the corner part 70 at the boundary between the web corresponding part 60 and the flange corresponding parts 62 and 63. On the other hand, the contact points 71a and 71b are inside the corner part 71 at the boundary between the flange corresponding parts 62 and 63 and the arm corresponding parts 65 and 66. At the contact points 71a and 71b, reaction forces are generated in directions that balance the reaction forces at 70a and 70b, respectively.

[0056] Here, by bringing the central part 60a on the lower surface (outer side) of the web corresponding part 60 shown in Fig. 7(b) into contact with the lower hole-type rolls 41 and 51 facing it, the bending of the angle formed by the flange corresponding parts 62 and 63 and the web corresponding part 60 can be efficiently performed. During the bending forming, since the web corresponding part 60 tends to bend downward in the figure, by bringing the lower hole-type rolls into contact with the central part 60a of the lower surface, which is away from both sides (corner part 70) of the web corresponding part 60, a bending moment can be effectively applied to both ends of the web corresponding part 60.

[0057] Also, at least in the second stand 23, which is the final stand, the upper surfaces (outer surfaces) 65a and 66a of the arm corresponding parts 65 and 66 become contact points in order to make the arm corresponding parts 65 and 66 substantially horizontal. In addition, by appropriately setting the allowance value of the roll gap as described above, as shown in Fig. 7(c), in the pass 45 of the first stand 22 and the pass 55 of the second stand 23, the upper inner portions 62a and 63a of the flange corresponding parts 62 and 63 of the finishing material 19a are brought into contact with the upper hole-type rolls 40 and 50, and the lower outer portions 62b and 63b of the flange corresponding parts 62 and 63 are brought into contact with the lower hole-type rolls 41 and 51. By bringing the portions shown in Fig. 7(c) into contact, it is possible to perform highly accurate bending forming by causing three-point bending due to the pass roll shape at the corner parts 70 and 71.

[0058] Further, as shown in Fig. 7(d), in addition to the portions described in Figs. 7(a) to 7(c) 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 dies 40 and 50. By bringing the portions shown in Fig. 7(d) into contact, the joint corresponding portions 68 and 69 can be formed to be substantially horizontal, and further highly accurate bending forming can be performed.

[0059] Here, the contact state between the finished material 19a and the hole die during the bending forming shown in Fig. 7(d) will be described in more detail with reference to Fig. 15. In Fig. 15, the contact portions of the hole die corresponding to the contact locations of the finished material 19a in Fig. 7(d) are shown surrounded by a broken line. Rounding (curved portions) are usually formed at the corner portions 90 (90a to 90d) of the upper hole die and the lower hole die facing the corner portions at the boundary between the web corresponding portion 60 and the flange corresponding portions 62 and 63 of the finished material 19a, and at the corner portions 94 (94a to 94d) of the upper hole die and the lower hole die facing the corner portions at the boundary between the flange corresponding portions 62 and 63 and the arm corresponding portions 65 and 66. The corner portions 90a and 90c of the upper hole die 40 (or 50) facing the inner sides 70a and 70b of the corner portions at the boundary between the web corresponding portion 60 and the flange corresponding portions 62 and 63 of the finished material 19a are brought into contact therewith. At that time, the outer sides of the corner portions at the boundary between the web corresponding portion 60 and the flange corresponding portions 62 and 63 and the corner portions 90b and 90d of the lower hole die 41 (or 51) facing them are not in contact. The lower hole die 41 (or 51) is in contact with the portion facing the central portion 60a of the lower surface (outer side) of the web corresponding portion 60 of the finished material 19a and the portions facing the outer lower portions 62b and 63b of the flange corresponding portions 62 and 63.

[0060] Further, the corner portions 94b and 94d of the lower hole die roll 41 (or 51) facing the inner sides 71a and 71b of the corner portions at the boundaries between the flange corresponding portions 62 and 63 and the arm corresponding portions 65 and 66 of the finishing material 19a are brought into contact therewith. At this time, the outer sides of the corner portions at the boundaries between the flange corresponding portions 62 and 63 and the arm corresponding portions 65 and 66 do not contact the corner portions 94a and 94c of the upper hole die roll 40 (or 50) facing thereto. The upper hole die roll is in contact with the portions facing the upper surfaces (outer surfaces) 65a and 66a of the arm corresponding portions 65 and 66 of the finishing material 19a and the portions facing the upper inner portions 62a and 63a of the flange corresponding portions 62 and 63. Further, the upper surfaces (outer surfaces) 68a and 69a of the joint corresponding portions 68 and 69 are in contact with the corresponding portions of the upper hole die roll 40 (or 50). Here, the contact state with the upper and lower hole die rolls corresponding to FIG. 7(d) has been described. However, for FIGS. 7(a) to (c), the corresponding hole die rolls may be similarly brought into contact with the contact portions of the finishing material 19a.

[0061] In addition, although the suitable contact portions for the finishing material 19a in the bending process have been described with reference to FIGS. 7(a) to (d) and FIG. 15, as shown in FIGS. 7 and 15, the respective contact portions in the bending process are not configured to reduce the thickness of the finishing material 19a. Specifically, a specific portion of the finishing material 19a is not configured to be pressed (i.e., reduced in thickness) from both sides by both the upper and lower hole die rolls, and the roll gap between the upper and lower hole die rolls is configured to be larger than the thickness of the finishing material 19a, so that the thickness reduction is not performed. If the web corresponding portion 60 and the flange corresponding portions 62 and 63 are not reduced in thickness, it is not necessary to unnecessarily increase the reduction reaction force.

[0062] Also, in FIGS. 7 and 15, an example of the configuration in which a part of each hole die roll is brought into contact with each corner portion 70 and 71 has been illustrated and described. However, the contact portions of each hole die roll in the present invention are not limited thereto. That is, in addition to the contact portions described above with reference to FIG. 7, further contact portions may be provided.

[0063] FIG. 13 is an explanatory view of the contact portion of the finished material 19a in the bending machine 20, and (a) to (d) show another example of the contact portion. Here, the same reference numerals are given to the same contact portions as in FIG. 7, and the description thereof is omitted. As shown in FIG. 13, as the contact portions, in addition to those shown in FIG. 7, the outer sides 70c, 70d (hereinafter also referred to as the outer sides 70c, 70d of the web-flange corner portion) of the corner portions 70 at the boundaries between the web corresponding portion 60 and the flange corresponding portions 62, 63, and the outer sides 71c, 71d (hereinafter also referred to as the outer sides 71c, 71d of the flange-arm corner portion) of the corner portions 71 at the boundaries between the flange corresponding portions 62, 63 and the arm corresponding portions 65, 66 may be provided.

[0064] That is, when the contact portions between each hole pattern roll and the finished material 19a are the portions shown in FIG. 13, the web-flange corner portion 70 and the flange-arm corner portion 71 of the finished material 19a are in contact with both the upper and lower hole pattern rolls, and are in a positional configuration where they are pressed down from both sides.

[0065] As described above, in hot rolling (rough rolling, intermediate rolling, finish rolling, etc.), which is an upstream process of bending, after the web-flange corner portion 70 and the flange-arm corner portion 71 are rolled so that their plate thicknesses are thicker than the product plate thickness, they may be conveyed to the bending machine 20. And the roll gap of the upper and lower hole pattern rolls at the portions facing the web-flange corner portion 70 and the flange-arm corner portion 71 of the finished material 19a may be set to be the product plate thickness. In such a dimensional configuration, in the bending machine 20, the web-flange corner portion 70 and the flange-arm corner portion 71 of the finished material 19a, which are in a state where their plate thicknesses are thicker than the product plate thickness, are pressed down by both the upper and lower hole pattern rolls, and the entire material is bent and formed.

[0066] Thus, although pressing is not generally performed during the bending of the finishing material 19a, pressing may be performed at only a predetermined partial location (see Fig. 13). When pressing is performed on the finishing material 19a, the entire thickness direction of the pressed region undergoes plastic deformation. Due to the plastic deformation caused by pressing, the stress distribution within the thickness due to bending shifts overall towards compression, and the bending moment acting on the corner portion becomes smaller. Therefore, the springback after bending becomes extremely small within the range where the entire thickness direction undergoes plastic deformation.

[0067] That is, as shown in Fig. 13, when bending is performed while pressing the web-flange corner portion 70 and the flange-arm corner portion 71, although the forming load increases compared to the case where the web-flange corner portion 70 and the flange-arm corner portion 71 are not pressed, it is possible to reduce the tensile stress on the outer side while suppressing an increase in the compressive stress on the inner side in the thickness direction of the corner portions 70 and 71 of the finishing material 19a during bending. This can reduce the springback after forming and minimize fluctuations in the dimensional shape in the longitudinal direction of the finishing material 19a. As a result, rolling can be performed in an optimal shape without being restricted by the product shape (angle), improving productivity and yield. Also, a product with a large cross-section and excellent dimensional accuracy can be manufactured at low cost without being restricted by the roll diameter of the rolling mill. Furthermore, compared to cold processing, the equipment can be made smaller, and dimensional shape and material stability can be achieved.

[0068] In the bending forming with the configuration shown in Fig. 13, if the pressing rate of the web-flange corner portion 70 and the flange-arm corner portion 71 exceeds 20%, the stretching balance of each part within the cross-section cannot be achieved, and the shape may collapse. Therefore, the pressing rate in bending forming is preferably 20% or less, more preferably 2 - 10%. Even if the pressing is 2%, the entire thickness direction of the web-flange corner portion 70 and the flange-arm corner portion 71 becomes a plastic region, making it possible to reduce the springback after bending. However, it is necessary to adjust the thickness of the web-flange corner portion 70 and the flange-arm corner portion 71 of the material to be rolled in the rolling process so as to satisfy such pressing rate conditions.

[0069] Also, when the bending machine 20 is composed of multiple stands, it is possible to perform pressing down of the corner portions 70 and 71 at all stands. However, if the corner portions 70 and 71 are pressed down at least at the final stand (the second stand 23 in this embodiment), the effect of reducing the springback after forming can be enjoyed.

[0070] According to the configuration described above with reference to FIGS. 7 and 13, the roll gap in each of the upper and lower pass rolls of the bending machine 20 is set to be larger than the thickness of the flange corresponding portion and the web corresponding portion of the finishing material 19a. Thus, for example, even if a difference occurs in the thickness of the left and right flange corresponding portions of the material to be rolled due to the displacement in the thrust direction of the upper and lower pass rolls in the rolling process (rough rolling to finish rolling), it is possible to avoid a situation where only one side of the flange corresponding portion is bent and formed with thickness reduction, and the material passing becomes unstable.

[0071] Furthermore, as described above, the bending is performed hot. Preferably, the finishing rolling mill 19 and the bending machine 20 are arranged in tandem, and the finishing rolling and the bending are continuously performed hot, so that the temperature drop of the material to be rolled is reduced. Here, hot finishing rolling and bending refer to rolling and forming at a temperature before the transformation of the material to be rolled is completed. By performing bending under such conditions, compared with the conventional cold bending, the forming load applied to the bending machine 20, material deterioration such as elongation and toughness reduction associated with bending, and residual stress can be reduced.

[0072] In this way, bending is performed as shown in Fig. 6, and the hat-shaped steel sheet pile, which is the product, is manufactured. In the bending machine 20, the finishing material 19a is formed by the pass rolls, and a three-point bending moment is generated at the corner portion due to the shape of the pass rolls, and the corner portion is further bent to approach the product shape. At this time, each pass roll contacts only at a predetermined position of the finishing material 19a shown in Fig. 7 or Fig. 13. Although the forming performed by the respective pass rolls 45 and 55 has been described with reference to Figs. 6(b) and 6(c), these bending processes are continuously performed on a single material (finishing material 19a), and usually, a single material is formed in a state where it passes through both the first stand 22 and the second stand 23 simultaneously (i.e., in a tandem state).

[0073] In the method for manufacturing a steel sheet pile according to the present embodiment, bending is performed using the bending machine 20 configured as described above, and a hat-shaped steel sheet pile product can be efficiently manufactured without using a large and complex mechanism mill or multiple mills. In addition, it can be applied without problems even when manufacturing a large hat-shaped steel sheet pile product. In the present embodiment, bending is performed hot by directly connecting the bending machine 20 after the finishing rolling mill 19. By this, compared with cold bending, the bending reaction force is small, the springback is small, and the number of bending steps can be reduced.

[0074] 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.

[0075] For example, in the above-described embodiment, the case where the bending machine 20 is composed of the first stand 22 and the second stand 23 has been illustrated and described, but the present invention is not limited thereto. For example, the bending machine 20 may be a single stand, or may be composed of any number of multiple stands. When the bending machine 20 is composed of multiple stands, since bending can be shared at each stand, it is possible to reduce the shape change of the joint corresponding portions 68 and 69 associated with bending. The number of stands is preferably determined from the balance between the bending angle and the capital investment. For example, if the bending angle is about 20° to 30°, two stands are preferable.

[0076] Also, in the above-described embodiment, the upper and lower pass rolls of the bending machine 20 may be configured such that only one of the upper and lower rolls is driven and the other is not driven. By adopting a configuration in which only one of the upper and lower pass rolls is driven, when bending is performed in a tandem state of multiple stands, it becomes easier to balance the speed of the material passing through, and the generation of tension on the material to be rolled due to the imbalance of the speed balance between multiple stands is suppressed, and the stabilization of the material passing through and the suppression of unnecessary shape changes of the material to be rolled are achieved. In addition, since the drive mechanisms such as the motor, spindle, and gears for driving the rolls can be simplified, downsizing of the equipment and reduction of the equipment cost are realized.

[0077] Also, in the above-described embodiment, the bending machine 20 and the finishing rolling mill 19 may perform material passing in a tandem state. By adopting a tandem configuration, the tip of the material to be rolled can be pushed into the bending machine 20 by the finishing rolling mill 19, and the biting stability of the material to be rolled in the bending machine 20 is achieved. In this case, it is preferable that the height of the upper surface of the table roller of the finishing rolling mill 19 and the height of the upper surface of the web corresponding portion of the lower pass roll in the bending machine 20 are substantially the same.

[0078] Further, in the bending forming machine 20 described in the above embodiment, it is preferable to supply a lubricant or the like to the contact portion between the material to be rolled (finished material 19a) and each pass roll for lubrication. In particular, the lower surface of the web corresponding portion 60 and the upper surfaces of the arm corresponding portions 65 and 66 locally contact the pass roll, and the relative sliding speed is high. Therefore, scratch marks are likely to occur in this region of the product after bending forming. Accordingly, it is necessary to lubricate particularly the contact portions between the lower surface of the web corresponding portion 60 and the upper surfaces of the arm corresponding portions 65 and 66 and the pass roll. By performing such lubrication, it becomes possible to manufacture a product of good quality without scratch marks.

[0079] Further, the rolling line L described in the above embodiment is preferably configured to be able to cope with the production of products of different thicknesses. Also in the bending forming machine 20 of this rolling line L, it is preferable not to perform thickness reduction of the finished material 19a in the same manner as in the above embodiment. That is, after performing a rolling process (rough rolling to finish rolling) to make the thickness of the finished material 19a the thickness dimension of the product, the finished material 19a is formed into a cross-sectional shape approximated to the product by the bending forming machine 20 without performing thickness reduction of the finished material 19a. In such a case, in the bending forming machine 20, the roll gap in the pass 45 and the pass 55 is adjusted so as to cope with the change in the thickness of the web corresponding portion 60 and the flange corresponding portions 62 and 63 of the finished material 19a.

[0080] Here, for example, as shown in FIG. 8, in the pass 45, the roll gap of the portion 45a facing the web corresponding portion 60 (hereinafter referred to as the web portion 45a) is set as tw, the roll gap of the portion 45b facing the flange corresponding portions 62 and 63 (hereinafter referred to as the flange portion 45b) is set as tf, and further the angle of the flange portion 45b with respect to the web portion 45a (hereinafter referred to as the flange angle) is set as θ. When the roll gap of the pass 45 is increased by Δ in the vertical direction, as shown by the dotted line in FIG. 8, the roll gap of the web portion 45a is increased by Δtw (=Δ), and the roll gap of the flange portion 45b is increased by Δtf (=Δcosθ).

[0081] Since the flange angle of the pass in the rolling mill (rough rolling mill 10 to finish rolling mill 19) in the rolling process is different from the flange angle θ in the bending machine 20, even if the roll gaps of the rolling mill and the bending machine 20 are adjusted by the same amount, the change amount Δtf of the flange portion 45b in these rolling mill and bending machine 20 will be different. Specifically, since the flange angle θ in the bending machine 20 is larger than the flange angle of the finish rolling mill 19, the change amount Δtf in the bending machine 20 is smaller than the change amount Δtf in the finish rolling mill 19. Then, there is a possibility that the plate thickness of the finished material 19a is reduced in the flange portion 45b in the bending machine 20. For this reason, it is necessary to individually set the change amount of the roll gap in the rolling mill and the change amount of the roll gap in the bending machine 20 according to the change in the thickness of the product.

[0082] That is, the change amount of the roll gap in the rolling mill is set so that the thickness of the finished material 19a becomes the thickness dimension of the product.

[0083] On the other hand, the change amount of the roll gap in the bending machine 20 is set so that the finished material 19a of all assumed thicknesses is not subjected to plate thickness reduction when the finished material 19a is formed by the bending machine 20. In other words, the roll gap in the bending machine 20 is set to be larger than all these assumed thicknesses corresponding to the change in the thickness of the finished material 19a. Specifically, when the roll gap of the web portion 45a of the pass 45, for example, in the bending machine 20 is set to be A larger than the product thickness of that portion (product thickness + A) so that the finished material 19a is not subjected to plate thickness reduction in the web portion 45a, the roll gap of the flange portion 45b is set to be B larger than the product thickness of that portion so that the finished material 19a is not subjected to plate thickness reduction in the flange portion 45b either (product thickness + B). These A and B are each larger than 0, preferably 5 mm or less, and more preferably 0.5 mm to 3 mm. And the upper pass roll 40 and the lower pass roll 41 forming the pass 45 are designed so that the above roll gap can be set.

[0084] In the above description, the roll gap of the flange portion 45b is set to the product thickness + B. However, in the hole die 45, the roll gap of the arm portions facing the arm corresponding portions 65 and 66 is also set to the product thickness + C. Similar to A and B, C is greater than 0, preferably 5 mm or less, and more preferably 0.5 mm to 3 mm. In the case of a hat-shaped steel sheet pile, since the web corresponding portion and the arm corresponding portion of the product are horizontal, A and C are substantially the same. Also, the roll gap of the other hole die 55 is set in the same manner as the roll gap of the hole die 45.

[0085] According to this embodiment, while enjoying the same effects as the above-described embodiment, by adjusting the roll gap using the same upper and lower hole die rolls of the bending machine 20, products of different thicknesses can be manufactured. Therefore, the degree of freedom in the producible product size can be improved.

[0086] In the above embodiments and their modifications, the case of manufacturing a 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 that case, it may be considered that the direction of the joint and the upper and lower hole die rolls are arranged in reverse. Also, in the description regarding the above embodiments and their modifications, the case of manufacturing a hat-shaped steel sheet pile as the final product has been exemplified and described. However, the present invention is not limited to this, and it can also be applied, for example, to the manufacture of steel sheet pile products such as U-shaped steel sheet piles.

[0087] For example, since the U-shaped steel sheet pile does not have an arm corresponding portion unlike the hat-shaped steel sheet pile, when performing the bending forming according to the present invention on the U-shaped steel sheet pile, it may be brought into contact with the hole-shaped roll at the position shown by the thick line in FIG. 14. Further, similar to the hat-shaped steel sheet pile in the above embodiment, in addition to the contact with the hole-shaped roll, each corner portion may be pressed down and bent. As a result, similar to the case of performing bending while pressing down on the corner portion 70 and the corner portion 71 during the manufacture of the hat-shaped steel sheet pile, also in the U-shaped steel sheet pile, while suppressing an increase in the compressive stress on the inner side in the thickness direction of the corner portion of the finishing material during bending, the tensile stress on the outer side can be reduced, the springback after forming can be decreased, and the dimensional shape variation in the longitudinal direction of the finishing material can be reduced. Further, by performing bending on the outer surface of the joint corresponding portion formed near the other end of the flange corresponding portion and its tip without thickness reduction, it becomes possible to perform even more accurate bending.

[0088] In addition, in the above embodiment, the hole-shaped roll may be divided in the roll axis direction. For example, as shown in FIG. 9, the upper hole-shaped roll 40 is divided into two equal parts, the divided hole-shaped rolls 40a and 40b, in the horizontal direction via the spacer 110, and the lower hole-shaped roll 41 is divided into two equal parts, the divided hole-shaped rolls 41a and 41b, in the horizontal direction via the spacer 110. However, it is desirable that this spacer 110 does not come into contact with the material to be rolled. By inserting the spacer 110 in this way and further adjusting the horizontal width of the spacer 110, the length of the web of the steel sheet pile as the product can be adjusted. In the case of the hole-shaped roll in FIG. 9, instead of the contact portion 60a at the center of the lower surface of the web corresponding portion 60 in FIGS. 7(b) to (d), it may be brought into contact with the lower surface of the web corresponding portion 60 of the material to be rolled by the hole-shaped portions 42a and 42b outside the spacer 110 of the hole-shaped rolls 41a and 41b.

Example

[0089] (Example 1) According to the method for manufacturing a steel sheet pile according to the present invention, after hot finish rolling, hot bending forming at 20° is performed by a bending forming machine composed of two consecutive stands to manufacture a hat-shaped steel sheet pile. As a conventional technique, a comparison was made with the case where a hat-shaped steel sheet pile was manufactured by cold working using a plurality of supporting rolls made of flat rolls for bending forming.

[0090] According to the method for manufacturing a steel sheet pile according to the present invention, after cutting the rolled material after bending forming to the product length, the angle formed by the flange and the web increased by approximately 0.5° at most due to springback. Also, the total width difference in the longitudinal direction of the product at this time was approximately 4.5 mm.

[0091] On the other hand, according to the method for manufacturing a steel sheet pile according to the conventional technique, after cutting the rolled material after bending forming to the product length, the angle formed by the flange and the web increased by approximately 2.2° at most due to springback. Also, the total width difference in the longitudinal direction of the product at this time was approximately 25 mm.

[0092] (Example 2) Also, as Example 2 of the present invention, a first hat-shaped steel sheet pile product (steel sheet pile 1 in the table) with a web thickness of 15.0 mm, a flange thickness of 11.3 mm, and an arm thickness of 14.5 mm, and a second hat-shaped steel sheet pile product (steel sheet pile 2 in the table) with a web thickness of 17.0 mm, a flange thickness of 12.8 mm, and an arm thickness of 16.5 mm were manufactured from the same bending forming rolls. Therefore, with the dimensional conditions shown in Table 1 below, the rolls of the finish rolling mill and the two-stand bending forming machine were shared respectively, and by only adjusting the roll gap, hot bending forming was performed for manufacturing.

[0093]

Table 1

[0094] As shown in Table 1, bending forming was carried out with the roll gap of both the first stand and the second stand of the bending forming machine being 1.9 mm to 2.8 mm larger than the thickness of the finishing material (i.e., the roll gap of the finish rolling mill). As a result, a good product could be manufactured by adjusting the roll gap with a very low forming load compared to finish rolling.

Industrial Applicability

[0095] The present invention can be applied to, for example, a manufacturing method and a manufacturing apparatus for steel sheet piles such as hat-shaped steel sheet piles and U-shaped steel sheet piles.

Explanation of Signs

[0096] 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 machine 22... First stand 23... Second stand 40... Upper pass roll 41... Lower pass roll 44... Housing 45... Pass 45a... Web part 45b... Flange part 50... Upper pass roll 51... Lower pass roll 54... Housing 55... Pass 60... Web corresponding part 62, 63... Flange corresponding parts 65, 66... Arm corresponding parts 68, 69... Joint corresponding parts 70... Corner part 70a, 70b... Inner side of corner part 70c, 70d... Outer side of corner part 71... Corner part 71a, 71b... Inner side of corner part 71c, 71d... Outer side of corner part 110... Spacer L... Rolling line

Claims

1. A method for manufacturing a steel corrugated sheet, comprising performing hot rolling including rough rolling, intermediate rolling, and finish rolling on a material to be rolled, and then performing bending forming, wherein: the material to be rolled after the finish rolling includes at least a web corresponding portion, two flange corresponding portions each having one end connected to both ends of the web corresponding portion and having an angle extending wider than the product, and a corner portion that is a connection portion between the web corresponding portion and each of the flange corresponding portions; in the bending forming, the roll gaps of the upper and lower pass rolls corresponding to the web corresponding portion and the portions facing the flange corresponding portions are configured to be larger than the thicknesses of the web corresponding portion and the flange corresponding portions, respectively; a method for manufacturing a steel corrugated sheet, characterized in that a part of the upper and lower pass rolls is brought into contact with the inside of the corner portion by hot rolling using the upper and lower pass rolls to bend the corner portion, and a part of the upper and lower pass rolls is brought into contact with the other end of the flange corresponding portion or the vicinity thereof.

2. The method for manufacturing a steel corrugated sheet according to claim 1, characterized in that in the bending forming, the upper and lower pass rolls are brought into contact with the other end of the flange corresponding portion or the vicinity thereof so that a force is applied in a direction balancing the force applied due to the contact of the upper and lower pass rolls with the corner portion.

3. The method for manufacturing a steel corrugated sheet according to claim 1 or 2, characterized in that the roll gaps of the upper and lower pass rolls corresponding to the web corresponding portion and the portions facing the flange corresponding portions are set to be larger than the respective thicknesses in correspondence with changes in the thicknesses of the web corresponding portion and the flange corresponding portions.

4. In the hot rolling, the material to be rolled is rolled so that the plate thickness of the corner portion is thicker than the product plate thickness, The method for manufacturing a steel corrugated sheet according to any one of claims 1 to 3, characterized in that in the bending forming, the corner portion is pressed down by the upper and lower pass rolls.

5. The method for manufacturing a steel corrugated sheet according to any one of claims 1 to 4, characterized in that in the bending forming, only one of the upper and lower pass rolls is driven.

6. The method for manufacturing a steel corrugated sheet according to any one of claims 1 to 5, characterized in that in the bending forming, the contact portion between the material to be rolled and the upper and lower pass rolls is lubricated.

7. The manufacturing method of a steel corrugated sheet according to any one of claims 1 to 6, characterized in that the bending machine for performing the bending forming and the finishing rolling machine for performing the finishing rolling are tandem.

8. The rolled material after the finishing rolling is provided with an arm corresponding portion that connects to the other end of the flange corresponding portion. The manufacturing method of a steel corrugated sheet according to any one of claims 1 to 7, characterized in that the upper and lower pass rolls contact a part of the upper and lower pass rolls inside the corner portion to bend the corner portion, and the upper and lower pass rolls are contacted so that a force is applied to another corner portion, which is the connection portion between the flange corresponding portion and the arm corresponding portion, in a direction that balances with the force applied due to the contact of the upper and lower pass rolls with the corner portion.

9. In the bending forming, a pass roll facing the web corresponding portion is contacted outside the web corresponding portion. The manufacturing method of a steel corrugated sheet according to claim 8, characterized in that a pass roll facing the arm corresponding portion is contacted on the outer surface of the arm corresponding portion.

10. The rolled material after the finishing rolling is provided with a joint corresponding portion formed at the tip of the arm corresponding portion. The manufacturing method of a steel corrugated sheet according to claim 9, characterized in that in the bending forming, a pass roll facing the joint corresponding portion is contacted on the outer surface of the joint corresponding portion so that the joint corresponding portion becomes substantially horizontal.

11. In the hot rolling, the rolled material is rolled so that the plate thickness of the other corner portion becomes thicker than the product plate thickness. The manufacturing method of a steel corrugated sheet according to any one of claims 8 to 10, characterized in that in the bending forming, the other corner portion is pressed down by the upper and lower pass rolls.

12. The manufacturing method of a steel corrugated sheet according to any one of claims 1 to 11, characterized in that the steel corrugated sheet is a hat-shaped steel corrugated sheet.

13. The rolled material after the finishing rolling is provided with a joint corresponding portion formed at the tip of the flange corresponding portion. The manufacturing method of a steel corrugated sheet according to any one of claims 1 to 7, characterized in that in the bending forming, a pass roll facing the joint corresponding portion is contacted on the outer surface of the joint corresponding portion so that the joint corresponding portion becomes substantially horizontal.

14. The manufacturing method of a steel corrugated sheet according to claim 13, characterized in that the steel corrugated sheet is a U-shaped steel corrugated sheet.

15. A manufacturing apparatus for steel roofing sheets, which has a bending machine that performs rough rolling, intermediate rolling, and finish rolling on a material to be rolled by hot rolling and then performs bending forming. After the finish rolling, the material to be rolled includes at least a web corresponding portion, two flange corresponding portions each having an angle with one end connected to both ends of the web corresponding portion and extending wider than the product, and a corner portion that is a connecting portion between the web corresponding portion and each of the flange corresponding portions. The bending machine has upper and lower pass rolls and bends the corner portion hot using the upper and lower pass rolls. The roll gaps of the portions of the upper and lower pass rolls facing the web corresponding portion and the flange corresponding portion are configured to be larger than the thicknesses of the web corresponding portion and the flange corresponding portion, respectively, during bending forming. The bending machine is configured to bend the corner portion by bringing a part of the upper and lower pass rolls into contact with the inside of the corner portion hot using the upper and lower pass rolls, and bringing a part of the upper and lower pass rolls into contact with the other end of the flange corresponding portion or the vicinity thereof. A manufacturing apparatus for steel roofing sheets, characterized in that.

16. The manufacturing apparatus for steel roofing sheets according to claim 15, wherein the upper and lower pass rolls have a shape such that when a part of the upper and lower pass rolls is brought into contact with the inside of the corner portion, a force is applied to the other end of the flange corresponding portion or the vicinity thereof in a direction that balances the force applied due to the contact.

17. The manufacturing apparatus for steel roofing sheets according to claim 15 or 16, wherein the roll gaps of the portions of the upper and lower pass rolls facing the web corresponding portion and the flange corresponding portion are set to be larger than the respective thicknesses in correspondence with changes in the thicknesses of the web corresponding portion and the flange corresponding portion.

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