Method for manufacturing steel sheet piles

Abstract

To alleviate a load on a steel sheet by a cut member during cutting of a steel sheet, and a load on the cut member.SOLUTION: A manufacturing method of a steel sheet pile includes: uncoil step S1 of unwinding a belt-like steel sheet out of a coil roll; press molding step S2 of performing press working on two side end parts of the steel sheet extending along the unwinding direction, and forming at least one hole; roll molding step S3 of performing roll molding on the side end parts where the holes are formed respectively, and forming a joint part by folding the steel sheet so as to face each other with a predetermined interval in the side end parts; and cut step S4 of inserting a lower blade member into a position that is not overlapped with the holes, making an upper blade member approach the steel sheet from the side opposite to the lower blade member at the position of the holes in the side end part, and cutting the steel sheet in the width direction. In roll molding step S3, the steel sheet is folded in such a manner that the side end parts are overlapped with the holes in the approach direction of the upper blade member in cut step S4 including side edges.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing steel sheet piles.

Background Art

[0002] Steel sheet piles are known in which the joints are fitted together and driven into the ground. Steel sheet piles are formed of strip-shaped steel plates and are widely used as earth retaining walls when constructing underground structures or as temporary partitions when constructing port and water area facilities (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, generally, a steel sheet pile is formed by unwinding a coil roll formed by winding a strip-shaped steel plate with an uncoiler, and the unwound steel plate is formed into a predetermined cross-sectional shape by passing through a roll forming machine. The steel plate 1000 formed by the roll forming machine has a web portion 1100, a flange portion 1200, and a joint portion 1300, as shown in FIG. 12. The joint portion 1300 is formed by rounding and folding back the end portion of the steel plate in the width direction W.

[0005] The steel plate 1000 that has undergone a roll forming process to manufacture a steel sheet pile is cut to a predetermined length. In FIG. 13 showing the time of cutting the steel plate 1000, in order to prevent the joint portion 1300 from being crushed, the lower blade member 310 is inserted into the joint portion 1300 to support the steel plate 1000 from below. Next, the upper blade member 320 is brought close to the steel plate 1000 in the approaching direction A toward the steel plate 1000 from the side opposite to the lower blade member 310 to cut the steel plate 1000 in the width direction W.

[0006] Since the joint part 1300 is folded by roll forming, it becomes a portion 1400 where the plate materials overlap in plan view. The lower blade member 310 is pressed from above by the steel plate 1000 that is cut by the upper blade member 320. Therefore, there is a concern that an excessive load is applied to the neck portion 313 of the lower blade member 310 inserted into the joint part 1300 during cutting, shortening the life of the lower blade member 310.

[0007] Further, since the upper blade member 320 cuts the overlapping portion 1400 of the plate materials, the load on the upper blade member 320 during cutting has been large.

[0008] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a technique for reducing the burden on the blade member during cutting of a steel plate when manufacturing a corrugated steel sheet.

Means for Solving the Problems

[0009] In order to solve the above problems, according to the present invention, an uncoiling step of unwinding a strip-shaped steel plate from a coil roll, a press forming step of performing press working on two side end portions of the steel plate extending along the unwinding direction to form at least one hole, a roll forming step of performing roll forming on each of the side end portions where the holes are formed to bend the steel plate so as to face each other with a predetermined interval at the side end portions to form a joint part, and a cutting step of inserting a lower blade member at a position not overlapping the hole and approaching the upper blade member from the side opposite to the lower blade member at the position of the hole at the side end portion to cut the steel plate in the width direction, and in the roll forming step, the steel plate is bent so that the side end portion overlaps the hole in the approaching direction of the upper blade member in the cutting step including the side edge.

[0010] Further, in the press forming step, two holes may be formed side by side in the width direction of the steel plate at each side end portion, and in the roll forming step, the steel plate may be bent so that the two holes do not overlap each other in the approaching direction of the upper blade member.

[0011] Also, in the press forming step, a plurality of slits may be formed across the width direction of the steel plate between the holes at the two side ends.

[0012] Also, in the press forming step, circular holes may be formed.

Advantages of the Invention

[0013] According to the present invention, the load on the cutting member during cutting of the steel plate can be reduced.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

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Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a plan view of a steel sheet pile 100 manufactured by the method according to the first embodiment. For convenience of explanation, the length direction of the steel sheet pile 100 is defined as the “extending direction L”, and the direction intersecting the extending direction L is defined as the “width direction W”.

[0017] The steel sheet pile 100 is used, for example, in various construction works such as quay wall construction, earth retaining construction, and foundation construction. The steel sheet pile 100 is driven into the ground along the extending direction L.

[0018] FIG. 2 is a perspective view of the tip portion of the steel sheet pile 100 shown in FIG. 1. The steel sheet pile 100 includes a web portion 110, a pair of flange portions 120, and a pair of joint portions 130. The web portion 110 extends in the width direction W of the steel sheet pile 100. The web portion 110 has two flat portions 111 and a raised portion 112. The raised portion 112 is located between the two flat portions 111. The raised portion 112 extends along the extending direction L. The raised portion 112 is formed in a substantially U shape when the steel sheet pile 100 is viewed in the extending direction L.

[0019] The pair of flange portions 120 extend along the extending direction L at both ends in the width direction W of the web portion 110. The flange portion 120 is bent so as to stand upright with respect to the web portion 110. The flange portion 120 is bent toward the side where the raised portion 112 bulges.

[0020] The ends of the respective flange portions 120 on the side opposite to the web portion 110 are bent away from each other to form a joint portion 130. The joint portion 130 is folded back toward the side of the web portion 110. The cross-sectional shape of the joint portion 130 is substantially U-shaped. Adjacent steel sheet piles 100 are connected to each other via the joint portion 130.

[0021] The joint portion 130 has an extension portion 131, a curved portion 132, and an opposing portion 133. The extension portion 131 is folded back on the side opposite to the raised portion 112 in the width direction W with respect to the flange portion 120. The extension portion 131 extends substantially parallel to the flat portion 111 of the web portion 110 in the width direction W.

[0022] The curved portion 132 extends from one end of the extension portion 131 on the side opposite to the flange portion 120 toward the web portion 110. The curved portion 132 is convex and rounded toward the side opposite to the raised portion 112 in the width direction W.

[0023] The opposing portion 133 extends from one end of the curved portion 132 on the side opposite to the extension portion 131 toward the flange portion 120. The opposing portion 133 faces the extension portion 131 with a predetermined interval therebetween. A space S is defined by the flange portion 120 and the joint portion 130. The surface of the opposing portion 133 facing the width direction W is spaced apart from the flange portion 120. In the present embodiment, the joint portion 130 includes the extension portion 131, the curved portion 132, and the opposing portion 133.

[0024] When connecting the steel sheet piles 100 in the width direction W, the steel sheet piles 100 with the directions in which the raised portions 112 are raised being opposite to each other are connected. By the opposing portion 133 of one joint portion 130 entering into the mutual space S, the adjacent steel sheet piles 100 are connected to each other.

[0025] At the edge of the joint portion 130 in the extending direction L, a notch 134 is formed. The notch 134 is formed along the extending direction of the substantially U-shaped joint portion 130. The extending direction of the notch 134 extends along the extending direction L from the end face 140 facing the extending direction L of the steel sheet pile 100 and turns in the width direction W so as to be rounded.

[0026] Next, a method for manufacturing the steel sheet pile 100 will be described. FIG. 3 is a flowchart showing the manufacturing steps of the steel sheet pile 100. The manufacturing method according to the present embodiment includes an uncoiling step S1 of unwinding a strip-shaped steel plate 200 from a coil roll, a press forming step S2 of performing press working on two side end portions 210 of the steel plate 200 extending along the unwinding direction (extending direction) L to form at least one hole 220, a roll forming step S3 of performing roll forming on each of the side end portions 210 where the holes 220 are formed to bend the steel plate 200 so as to face each other with a predetermined interval at the side end portions 210 to form the joint portion 130, and a cutting step S4 of inserting a lower blade member 310 at a position that does not overlap with the hole 220 and bringing an upper blade member 320 closer to the steel plate 200 from the side opposite to the lower blade member 310 at the position of the hole 220 at the side end portion 210 to cut the steel plate 200 in the width direction W. In the roll forming step S3, the steel plate 200 is bent so that the side end portion 210 overlaps with the hole 220 in the approaching direction A of the upper blade member 320 in the cutting step S4 including the side edge 211. Hereinafter, the manufacturing method of the steel sheet pile 100 will be specifically described.

[0027] A coil roll (not shown) formed by winding a long steel plate 200 into a roll shape is set on an uncoiler. First, the steel plate 200 is unwound from the coil roll by the uncoiler (uncoiling step S1). The steel plate 200 unwound from the uncoiler is sequentially processed on the production line.

[0028] The unrolled steel sheet 200 is sent to a press device. In the press device, holes 220 (pre-notches) are formed in the steel sheet 200 (press forming step S2). FIG. 4 is a plan view of the steel sheet 200 after the press forming step S2. By performing press working on the steel sheet 200 with the press device, the holes 220 are processed in two side end portions 210 of the steel sheet 200 in the width direction W.

[0029] The holes 220 are substantially oval in plan view. Here, the "oval" means a shape in which parallel sides spaced apart from each other by a predetermined interval in the extending direction L are connected by an arc in the width direction W. Note that the shape of the holes 220 is not limited to oval, and may be circular or elliptical.

[0030] The interval between the sides of the holes 220 that are separated in the extending direction L and extend in the width direction W is, for example, equal to or greater than the thickness of the cutting blade (upper blade member 320), and the maximum interval between the arc portions of the holes 220 in the width direction W is, for example, within a range of 2 to 4 times the thickness of the cutting blade. The position where the holes 220 are formed in the extending direction L is determined according to the length of the steel corrugated sheet 100 to be manufactured.

[0031] The holes 220 respectively formed in the side end portions 210 of the steel sheet 200 in the width direction W are formed at the same position in the extending direction L. The holes 220 are formed, for example, at a predetermined interval from the side edge 211 of the steel sheet 200 along the extending direction L.

[0032] The steel sheet 200 in which the holes 220 are formed through the press forming step S2 is sent to a roll forming machine. FIG. 5 is a plan view of the steel sheet 200 after the roll forming step S3. By performing roll forming on the steel sheet 200 with the roll forming machine, a web portion 110 (ridge portion 112), a flange portion 120, and a joint portion 130 are formed in the steel sheet 200 (roll forming step S3).

[0033] While bending the tip side of the side end portion 210 in the width direction W outward with respect to the flange portion 120, further bend it toward the web portion 110, and then fold back the tip of the side end portion 210 so that the side edges 211 of the two side end portions 210 face each other in the width direction W.

[0034] As a result, the side end portions 210 of the steel plate 200 face each other with a predetermined interval in the thickness direction of the steel plate 200. Thereby, the joint portion 130 is formed on the steel plate 200. A space S is formed inside the joint portion 130. When connecting the steel sheet piles 100 in the width direction W, the joint portions 130 of adjacent steel sheet piles 100 are connected through each other's spaces S.

[0035] The joint portion 130 is formed by bending the steel plate 200 so that the side end portion 210 overlaps the hole 220 including the side edge 211 in the approaching direction A in which the upper blade member 320 approaches the steel plate 200 in the cutting step S4 described later. In a state where the joint portion 130 is formed, the side edge 211 of the steel plate 200 is located outside the edge of the hole 220 located on the center side of the steel plate 200 in the width direction W.

[0036] The hole 220 in the joint portion 130 starts from the flange portion 120 and extends from the extending portion 131 to the curved portion 132 of the joint portion 130. The opposing portion 133 of the joint portion 130 does not face any part of the steel plate 200 in the approaching direction A at the position of the hole 220, and is exposed through the hole 220 in the extending portion 131 and the curved portion 132.

[0037] The steel plate 200 in which the joint portion 130 is formed through the roll forming step S3 is sent to a cutting machine. In the cutting machine, individual steel sheet piles 100 are cut from the steel plate 200 by cutting the steel plate 200 to a predetermined length (cutting step S4). FIG. 6 is a schematic diagram for explaining the cutting method of the steel plate 200 in the cutting step S4. The steel plate 200 is cut by the cutting machine along a virtual line V1 (see FIG. 5) connecting the two holes 220 in the width direction W.

[0038] The cutting machine is provided with blade members (lower blade member 310 and upper blade member 320). The steel plate 200 sent to the cutting machine is supported from below by the lower blade member 310. The lower blade member 310 has a support main body portion 311 and an insertion portion 312. The support main body portion 311 supports mainly the web portion 110 and the flange portion 120 of the steel plate 200 from below.

[0039] The insertion portion 312 is inserted into the space S of the joint portion 130. In a state where the insertion portion 312 of the lower blade member 310 is inserted into the space S of the joint portion 130, the insertion portion 312 does not expose through the hole 220 of the steel plate 200. That is, the insertion portion 312 is covered by the joint portion 130.

[0040] The upper blade member 320 approaches the steel plate 200 supported by the lower blade member 310 from below. In the cutting step S4, the lower blade member 310 is inserted into the space S of the joint portion 130, and the upper blade member 320 is brought close to the steel plate 200 from the side opposite to the lower blade member 310 to cut the steel plate 200. The approaching direction A of the upper blade member 320 to the steel plate 200 and the lower blade member 310 is, for example, a direction from above to below in the vertical direction.

[0041] As shown in FIG. 7 which is a flowchart showing the conventional manufacturing steps of the steel sheet pile, the conventional manufacturing method includes an uncoiling step S10, a roll forming step S30, and a cutting step S40, and does not include a step corresponding to the press forming step S2 according to the above embodiment. Therefore, as shown in FIG. 13, the hole 220 formed in the steel plate 200 in the above embodiment is not formed in the steel plate 1000. That is, in the joint portion 1300 of the steel plate 1000, the extending portion 1311 and the opposing portion 1313 are always opposed to each other in the approaching direction A along the extending direction L of the steel plate 1000.

[0042] In the cutting step S40 of the conventional manufacturing method, the upper blade member 320 first cuts the extending portion 1311, then cuts the curved portion 1312, and finally cuts the opposing portion 1313. Therefore, during a single cutting operation, the load on the lower blade member 310 by the upper blade member 320 is first transmitted to the insertion portion 312 when cutting the extending portion 1311, and then transmitted to the insertion portion 312 via the extending portion 1311 when cutting the opposing portion 1313.

[0043] In the conventional cutting step S40, the upper blade member 320 is at the same location and must cut two locations, namely the extending portion 1311 and the opposing portion 1313 of the joint portion 430, in a single cutting step S40. Therefore, the portion of the upper blade member 320 that cuts the extending portion 1311 and the opposing portion 1313 of the joint portion 1300 is under a greater load during cutting compared to other portions.

[0044] Also, in the lower blade member 310, the transition portion (neck portion) 313 from the support body portion 311 to the insertion portion 312 has a thinner wall thickness compared to other portions. The two impacts caused by cutting the extending portion 1311 and the opposing portion 1313 in a single cutting step S40 will be transmitted to the transition portion 313. As the cutting step S40 is repeated, the accumulation of fatigue in the neck portion 313 of the lower blade member 310 also tends to increase.

[0045] On the other hand, according to the manufacturing method according to the present embodiment, in the cutting step S4, since the upper blade member 320 cuts the steel plate 200 at the position of the hole 220, it does not cut the extending portion 131 that covers the insertion portion 312 of the lower blade member 310. Therefore, the portion that the upper blade member 320 cuts in the joint portion 130 is mainly the opposing portion 133.

[0046] Also, for example, when the hole 220 is formed in a quadrilateral such as a rectangle, stress concentrates at the corners during cutting, and there is a risk of unintended cracks occurring in the steel plate 200. The hole 220 formed in the press forming step S2 of the manufacturing method according to the above embodiment is oval and thus has no corners. Therefore, it is possible to avoid stress concentration at the edge of the hole 220 during cutting.

[0047] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments and includes all aspects included in the concept of the present invention and the scope of the claims. Hereinafter, the differences from the manufacturing method according to the first embodiment will be mainly described, and the same parts will be denoted by the same reference numerals and the description thereof will be omitted.

[0048] The manufacturing method according to the second embodiment will be described with reference to FIG. 8. FIG. 8 is a plan view of a steel plate 200 in which slits 230 are formed in the press forming step S2 in the method according to the second embodiment.

[0049] In the manufacturing method according to the second embodiment, in the press forming step S2, a plurality of slits 230 are formed across the width direction W of the steel plate 200 between the holes 220 at the two side end portions 210. The steel plate 200 in which the slits 230 are formed is then sent to the roll forming step S3 and finally sent to the cutting step S4.

[0050] Each slit 230 is formed at a predetermined interval from each other in the width direction W. In the cutting step S4, the steel plate 200 is cut by a cutting machine along a virtual line V2 passing through the two holes 220 and the slits 230 in the width direction W.

[0051] By providing the slits 230, the load on the upper blade member 320 and the load on the steel plate 200 by the upper blade member 320 can be reduced.

[0052] The manufacturing method according to the third embodiment will be described with reference to FIG. 9. FIG. 9 is a plan view of a steel plate 200 in which two holes 240 are formed in the press forming step S2 in the method according to the third embodiment. In the press forming step S2, two holes 240 are formed side by side in the width direction W of the steel plate 200 at each side end portion 210.

[0053] The hole 240 is substantially oval in plan view. Here, the "oval shape" means a shape in which parallel sides spaced apart from each other by a predetermined interval in the extending direction L are connected by an arc in the width direction W. Note that the shape of the hole 240 is not limited to an oval shape, and it may be circular or elliptical.

[0054] The interval between the sides of the hole 240 that are separated in the extending direction L and extend in the width direction W is, for example, equal to or greater than the thickness of the cutting blade (upper blade member 320). The maximum interval between the arc portions of the hole 240 in the width direction W is, for example, within the range of 1 to 1.5 times the thickness of the cutting blade. The position where the hole 240 is formed in the extending direction L is determined according to the length of the steel sheet pile 100 to be manufactured. The interval in the width direction W between the holes 240 at each side end portion 210 is, for example, 10 mm, and it may be 10 mm or more.

[0055] The holes 240 formed at the side end portions 210 of the steel plate 200 in the width direction W are formed at the same position in the extending direction L. The hole 240 is formed at a predetermined interval, for example, from the side edge 211 of the steel plate 200 along the extending direction L.

[0056] In the roll forming step S3, the side edge portion 210 of the steel plate 200 is bent so that the two holes 240 do not overlap each other to form the joint portion 130. FIG. 10 is a plan view of the steel plate 200 after the roll forming step S3.

[0057] FIG. 11 is a schematic diagram for explaining the cutting method of the steel plate 200 in the cutting step S4. One of the two holes 240 is formed in the extending portion 131, and the other hole 240 is formed at the transition portion from the curved portion 132 to the opposing portion 133. The two holes 240 do not overlap in the approaching direction A, and the tip of the opposing portion 133 overlaps the hole 240 in the extending portion 131. Thereby, the steel plate 200 of the joint portion 130 at the cutting position does not overlap in the approaching direction A of the upper blade member 320.

[0058] Since the cutting amount of the steel plate 200 by the upper blade member 320 can be reduced in the approaching direction A, the loads applied to the lower blade member 310 and the upper blade member 320 can be reduced.

[0059] Note that each configuration of the above-described embodiments may be appropriately and selectively combined so as to achieve at least some of the above-described problems and effects.

Explanation of Reference Numerals

[0060] 100 Steel sheet pile, 110 Web portion, 120 Flange portion, 130 Joint portion, 200 Steel plate, 210 Side edge portion, 211 Side edge, 220, 240 Hole, 230 Slit, 310 Lower blade member, 320 Upper blade member

Claims

1. An uncoiling step of uncoiling a strip-shaped steel plate from a coil roll, a press forming step of performing press working on two side end portions of the steel plate extending along the uncoiling direction to form at least one hole, a roll forming step of bending the steel plate so that portions forming the side end portions face each other with a predetermined interval in the thickness direction of the steel plate by performing roll forming on each of the side end portions where the holes are formed, thereby forming a joint portion, a cutting step of arranging the lower blade member such that an insertion portion, which is a part of the lower blade member, is covered by the joint portion in a state where the insertion portion is inserted into the space inside the joint portion, and then approaching the upper blade member from the side opposite to the lower blade member in the thickness direction at the position of the hole in the side end portion, which is a position shifted from the position where the lower blade member is arranged in the uncoiling direction, to cut the steel plate in the width direction, comprising in the roll forming step, bending the steel plate so that a portion including a side edge of the side end portion overlaps the hole in the approaching direction of the upper blade member in the cutting step A method for manufacturing a corrugated steel sheet, characterized by the above.

2. In the press forming step, two holes are formed side by side in the width direction of the steel plate at each side end portion, in the roll forming step, bending the steel plate so that the two holes do not overlap each other in the approaching direction The manufacturing method according to claim 1, characterized by the above.

3. The manufacturing method according to claim 1 or 2, characterized in that in the press forming step, a plurality of slits are formed across the width direction of the steel plate between the holes at the two side end portions.

4. The manufacturing method according to any one of claims 1 to 3, characterized in that in the press forming step, circular holes are formed.

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