KR20200112098A - Pipe haved dual type using corrugated plate and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a steel pipe with a double structure using a corrugated steel plate and a manufacturing method thereof, and more specifically, to a steel pipe having a double structure by being formed by a single corrugated steel plate and a manufacturing method thereof. In particular, the steel pipe with a double structure using a corrugated steel pipe of the present invention is formed by using a single corrugated steel plate to reduce fabrication costs. In addition, a first closed space and a second closed space extended in a longitudinal direction are alternately formed to provide a high strength against external pressure and to provide an evenly formed inside to facilitate the smooth movement of fluid. Furthermore, according to the method for manufacturing a steel pipe with a double structure using a corrugated steel pipe of the present invention, a single corrugated steel plate is shaped such that a ridge and a ridge may come in contact with each other in order to form a pipe with a double structure, thereby providing economic feasibility through simple fabrication processes and reduction in fabrication costs. In addition, the first closed space and the second closed space are formed to be alternately located, thereby fabricating a steel pipe with the inner circumferential surface formed in an even manner to provide a high strength of external pressure and to allow the smooth movement of fluid. To this end, the present method comprises: an uncoiling step; a corrugated steel plate shaping step; a corrugated steel pipe shaping step; a double structure steel pipe forming step; and a steel pipe cutting step.

Description

Steel pipe having a double structure using corrugated steel plate and a manufacturing method thereof {Pipe haved dual type using corrugated plate and manufacturing method thereof}

The present invention relates to a steel pipe having a double structure using a corrugated steel plate and a method for manufacturing the same, and to a steel pipe having a double structure by being formed from a single corrugated steel plate and a method for manufacturing the same.

In roads, ports, and sewage treatment plants, concrete fume pipes are usually used as a method to move fluids, but concrete fume pipes are difficult to transport and handle due to the increase in their own weight and volume. There was a cause of lengthening the air due to the decrease in workability due to the installation and disassembly of the wall and the increase in the connection part.

In addition, although the strength of the concrete fume pipe was high, it was easily damaged by a small impact applied from the outside during the transport and construction process.

As a solution to these causes, steel pipes with high external pressure strength, durability, and workability have been proposed, and lock seams having a hook shape are formed on both edges of a steel plate having a predetermined thickness, so that the lock seams are engaged with each other. Papyeong steel pipes with lighter load overall than concrete fume pipes are used to have the shape of a combined flat pipe.

However, these corrugated steel pipes have corrugated valleys repeatedly formed in the circumferential direction, and are bent at almost right angles with respect to the flow direction of water and sewage, and the pipe diameter has to be designed large due to the adverse function that hinders the normal flow of rainwater and sewage. There is a problem

To compensate for this problem, a lining is inserted inside as disclosed in Korean Patent Registration No. 10-1208203, or an inner tube is inserted as disclosed in Korean Utility Model Publication No. 20-0428386 to smooth the flow of fluid. I am doing it.

However, this structure has a problem in that the manufacturing process and the connection structure are complex, and the cost is increased because a separate member such as an inner tube or lining is required in addition to the corrugated steel sheet.

Republic of Korea Patent Publication No. 10-1208203: Lining double corrugated steel pipe and lining and manufacturing method thereof Republic of Korea Utility Model Publication No. 20-0428386: Corrugated steel pipe with a smooth inside

The present invention has been created to improve the above problems, and provides a steel pipe having a dual structure using a corrugated steel pipe having a double structure using a single corrugated steel plate, and a corrugated steel pipe formed smoothly and smoothly to move the fluid inside, and a method for manufacturing the same. I want to.

The steel pipe having a double structure using the corrugated steel pipe of the present invention to achieve the above object is the corrugated steel plate so that the locking seam connection portions bent in opposite directions to each other at both edges in the width direction of the corrugated steel plate formed with mountains and valleys It is formed through a lock shim formed by pressing the lock shim connection part that is mutually hung while winding in this spiral, and the mountain formed on the outer circumferential surface and the mountain formed on the inner circumferential surface are mutually closed so that the valleys adjacent to each other in the width direction of the corrugated steel sheet are in contact. A first closed space in which the inner and outer circumferential surfaces are helically extended in the longitudinal direction by being pressed in the adjacent direction and a second closed space helically extended in the longitudinal direction around the first closed space are formed. When the mountain formed on the side and the mountain formed on the other side are pressed in a direction adjacent to each other, the first closed space and the second closed space are formed, so that the width of the open side of the valley is narrower than the width of the closed side. Or it is characterized in that it has a curvature in a form in which the width of the lower end of the mountain is narrower than that of the upper part.

The corrugated steel sheet may have uneven portions formed on both sides so as to increase the frictional force between the mountains formed on one side and the mountains formed on the other side in a direction adjacent to each other so as to increase friction between the mountains mutually in contact with each other in the width direction.

Further, a method of manufacturing a steel pipe having a double structure using a corrugated steel pipe of the present invention includes an uncoiling step of unwinding a steel sheet wound on an uncoiler; A corrugated steel sheet forming step of forming the unwound steel sheet into a corrugated steel sheet having a continuous corrugation of valleys and mountains and bending at both edges in the width direction in opposite directions to form a locking seam connection portion capable of being engaged with each other; A corrugated steel pipe forming step of forming a corrugated steel pipe by forming a lock shim by pressing the lock shim connection portions which are in contact with each other while spirally winding the corrugated steel plate; The first closed space spirally extended in the longitudinal direction by pressing the mountains formed on the outer circumferential surface of the corrugated steel pipe and the mountains formed on the inner circumferential surface to close the valleys by contacting the mountains adjacent to each other in the longitudinal direction of the corrugated steel pipe. A double structure steel pipe forming step of forming a steel pipe having a double structure in which a second closed space is formed spirally extending in a longitudinal direction at a position opposite to the first closed space; It characterized in that it comprises a; steel joint cutting step of cutting the steel pipe to a predetermined length.

The corrugated steel sheet forming step is a corrugated steel sheet curvature of increasing the curvature of the corrugated steel sheet such that the width of the open side of the corrugated steel sheet is narrower than the width of the closed side, or the width of the lower end side of the mountain is narrower than the upper side. It is preferred to include an increasing step.

It is preferable that the method for manufacturing a steel pipe having a double structure using a corrugated steel pipe of the present invention further comprises a steel plate irregularity forming step of forming an irregularity on the outer peripheral surface of the steel sheet that has been unwound before the corrugated steel sheet forming step.

The steel pipe having a double structure using the corrugated steel pipe of the present invention is formed using one corrugated steel plate, so the manufacturing cost can be lowered, and the first closed space and the second closed space extended in the longitudinal direction are formed alternately to provide high external pressure strength. It has the advantage that the inside is formed smoothly, so that the fluid moves smoothly.

In addition, the manufacturing method of a steel pipe having a dual structure using a corrugated steel pipe of the present invention is economical because the manufacturing process is simple and the manufacturing cost can be lowered because the acid and the acid are formed in contact with each other using a single corrugated steel plate. And, since the first closed space and the second closed space are formed to be located alternately, there is an advantage that it is possible to manufacture a steel pipe having a smooth inner circumferential surface with high external pressure strength and smooth fluid movement.

1 is a side view of a corrugated steel pipe forming machine for manufacturing a double structure steel pipe according to an embodiment of the present invention,
2 is a front view of a corrugated steel sheet in which a corrugation is formed by a corrugated steel pipe forming machine according to an embodiment of the present invention,
3 is a front view showing a state in which the corrugated steel sheet of FIG. 2 is formed to increase the curvature,
FIG. 4 is a view showing a state in which the corrugated steel sheet is formed to have an increased curvature by the second roller part of the corrugated steel pipe forming machine of FIG. 3,
FIG. 5 is a view showing a state in which lock seam connection portions of the corrugated steel sheet of FIG. 4 interlock;
6 is a view showing a state in which a lock seam connection part is pressed to form a corrugated steel pipe by winding a corrugated steel sheet in a spiral according to an embodiment of the present invention,
FIG. 7 is a diagram showing a state in which an outer mountain and an inner mountain of the corrugated steel pipe of FIG. 6 are pressed in a direction adjacent to each other,
8 is a partial cross-sectional view of a steel pipe having a dual structure using a corrugated steel sheet according to an embodiment of the present invention,
9 is a block diagram of a method of manufacturing a steel pipe having a dual structure using a corrugated steel sheet according to an embodiment of the present invention,
10 is a perspective view of a steel pipe having a dual structure using a corrugated steel sheet according to an embodiment of the present invention,
11 is a perspective view of a steel pipe having a dual structure using a corrugated steel plate according to another embodiment of the present invention,
12 is a partial perspective view showing a state in which irregularities are formed on a corrugated steel plate applied to a steel plate having a dual structure using a corrugated steel plate according to another embodiment of the present invention.

Hereinafter, a steel pipe having a dual structure using a corrugated steel sheet according to a preferred embodiment of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

A typical corrugated steel pipe (not shown) has a disadvantage in that the fluid flow is not smooth because the mountains and valleys are continuously formed on the inner circumferential surface. A method of manufacturing a steel pipe having a dual structure using a corrugated steel plate according to an embodiment of the present invention is to manufacture a steel pipe having a double structure using a single corrugated steel plate, so that the inside is formed smoothly and fluid movement is smooth.

1 to 10 are views illustrating a steel pipe having a dual structure using a corrugated steel sheet and a method of manufacturing the same according to an embodiment of the present invention.

A steel pipe having a dual structure using a corrugated steel sheet according to an embodiment of the present invention and a method of manufacturing the same, refer to FIG. 9, an uncoiling step (S1), a corrugated steel sheet forming step (S2), and a corrugated steel pipe forming step. It includes (S5), a step of forming a steel pipe having a dual structure (S8), and a step (S9) of a joint end.

The uncoiling step (S1) is a step in which the steel sheet 100 wound around the uncoiler 10 is unwinded at a constant speed and supplied to the roll forming unit 20.

The corrugated steel sheet forming step (S2) includes a corrugated steel sheet forming step (S3) of forming a corrugation on the steel sheet, and a corrugated steel sheet curvature increasing step (S4) of increasing the curvature of the corrugated steel sheet.

In the steel plate corrugation forming step (S3), the steel plate 100 is passed through the roll forming unit 20 to form a wave shape, and both edges of the steel plate 100 are bent in opposite directions to lock seam connection portions 113 and 114 that are mutually engaging. Is the step of forming.

Referring to FIG. 1, the roll forming part 20 includes a first forming part in which a pair of first upper forming rollers and first lower forming rollers 22 and 23 disposed vertically are disposed in a plurality of steel plate extension directions ( 21), and second upper forming rollers 27 and second upper forming rollers 28 arranged vertically and in a plurality of second forming portions 26 arranged in a direction of extending the steel plate.

The first upper forming rollers and the first lower forming rollers 22 and 23 of the first forming part 21 are not specifically formed, but they are interlocked with the steel plate 100 interposed therebetween, so that the ribs 118 ) And mountains 119 are formed, and upper and lower pressing portions (not shown) that can pressurize the steel plate are formed, respectively, so that one and the other locking seam connection portions 113 and 114 bent in opposite directions at both edges are formed.

The shape of the upper and lower pressing parts is to press the steel plate so that a plurality of valleys 118 and mountains 119 extending in the longitudinal direction are formed on the steel plate 100, and one and the other locking seam connection parts 113 and 114 are formed on both sides of the steel plate. It is not limited if possible, but it is preferably formed to pressurize the steel plate 100 such that two to three valleys or mountains are formed between the two locking shim connection portions 103 and 104.

As shown in FIG. 3, the corrugated steel pipe curvature increasing step (S4) is performed by passing the corrugated steel plate 110 on which the valleys 118 and ridges 119 are formed through the second shaping unit 26, This is a step of increasing the curvature of the corrugated steel sheet so that the width of the open side of) is narrower than the width of the closed side, or the width of the lower end of the mountain 119 is narrower than the upper part.

The second upper forming roller 27 and the second lower forming roller 28, which are arranged up and down in the second molding part 26 to form a group, are arranged in a plurality of pairs in the longitudinal direction of the second molding part 26. Although not shown as, the corrugated steel sheets formed at the positions that are mutually intersected in the longitudinal direction to form the first corrugation in the first forming part 21 are sequentially formed in the width direction.

As shown in Fig. 4, the second upper forming roller 27 and the second lower forming roller 28 are formed so that the end in the radial direction from the center of rotation has a curved surface, but the width is tapered to become thinner from the edge side to the center side. It is preferably formed in a true form. This is to increase the curvature of the corrugated steel sheet so that the width of the open side of the valley 118 of the corrugated steel sheet formed in the first molding part is narrower than the width of the closed side, or the width of the bottom side of the mountain 119 becomes narrower than the upper part. It is for sake.

In the corrugated steel pipe forming step (S5), by supplying the corrugated steel plate 110 with increased curvature to the steel pipe forming machine 30, winding the corrugated steel plate 110 in a spiral shape and pressing the one side and the other side lock seam connection parts 113 and 114 in contact with each other. This is a step of forming the lock shim 125 to form a corrugated steel pipe 120.

Prior to the description of the corrugated steel pipe forming step (S5), the steel pipe forming machine 30 will be described first. The steel pipe forming machine 30 spirally rolls the corrugated steel plate 110 having a plurality of valleys 118 and 119 formed therein in a longitudinal direction, so that the one side and the other side lock seam connection parts 113 and 114 are connected to the lock seam 125 ) To form a cylindrical shape.

The process of forming the corrugated steel plate 110 into the corrugated steel pipe 120 by passing through the steel pipe forming machine 30 is as follows. As the tip of the corrugated steel plate 110 passes through the steel pipe molding machine 30, it is spirally rolled by the front guide roller 31 and the rear guide roller 32, which are components of the steel pipe molding machine 30, and is also in the process of rolling. As shown in Fig. 5, the one side lock shim connection part 113 and the other side lock shim connection part 114, which are the boundary parts, are close to each other so as to be able to be bitten.

In the steel pipe forming machine 30, an upper lock shim roller 33 and a lower lock shim roller 35 for forming a lock shim are axially coupled between the front guide roller 31 and the rear guide roller 32, so that the adjacent lock shim connection part (113, 114) is bitten and compressed while passing between the upper lock seam roller 33 and the lower lock seam roller 35, thereby forming a lock seam at the boundary of the spiral-shaped corrugated steel plate 110 A completely cylindrical corrugated steel pipe 120 is formed.

In addition, the steel pipe forming machine 30 has a first pressing roller (not shown) located outside the corrugated steel pipe 120 to form a dual structure steel pipe by pressing the mountain and the mountain of the corrugated steel pipe 120, and the corrugated steel pipe 120 ) Is provided with a second pressing roller (not shown) located inside.

The corrugated steel pipe forming step (S5) includes a corrugated steel sheet winding step (S6) and a lock shim forming step (S7). In the corrugated steel sheet winding step (S6), the front end of the corrugated steel sheet 110 is passed through the steel pipe molding machine 30 and is spirally formed by the front guide roller 31 and the rear guide roller 32, which are components of the steel pipe molding machine 30. This is a step of winding the corrugated steel sheet 110 by rolling.

The lock shim forming step (S7) includes the upper lock shim roller 33 and the lower lock shim roller 35 of the steel pipe forming machine 30 respectively positioned at the upper and lower sides of the lock shim connection parts 113 and 114 that are in contact with each other when the corrugated steel sheet 110 is wound. It is a step of forming the corrugated steel pipe 120 by forming the lock shim 125 by pressing using.

In the step of forming a steel pipe having a dual structure (S8), the peaks 119 and valleys 188 formed in the corrugated steel pipe are formed so that the valleys 118 are closed by contacting the mountains 119 adjacent to each other in the longitudinal direction of the corrugated steel pipe 120. This is a step of forming a steel pipe 130 having a double structure in which the first closed space 131 and the second closed space 133 spirally extended in the longitudinal direction by pressing in a direction adjacent to each other are formed.

Although not specifically shown, the first pressing roller and the second pressing roller of the steel pipe forming machine 30 are formed to be longer than the length apart from each other. The first pressing roller and the second pressing roller are respectively located on the outside and inside of the corrugated steel pipe 120 at the front side in the direction in which the lock shims formed on the upper lock shim roller 33 and the lower lock shim roller 35 are discharged. Each rotates in opposite directions. In addition, the first pressing roller and the second pressing roller are pressed so that the convex outward peaks 119 of the corrugated steel pipe 120 and the valleys 118 drawn inward are adjacent to each other, in the longitudinal direction of the corrugated steel pipe 120 They are in contact with the mountains on the same line of the same line, and the valleys of the same line are separated from each other by a distance that can be pressed so that they can be formed in contact with each other.

The corrugated steel pipe 120 pressurized by the first pressing roller and the second pressing roller is a steel pipe having a double structure having a first closed space 131 and a second closed space 133 because the mountains are folded or the valleys are in contact with each other. It is formed with 130.

The steel pipe cutting step (S9) is a step of cutting the formed pipe steel pipe 130 into a predetermined length by a cutter (not shown) in the steel pipe forming machine 30. The steel pipe 120 that is continuously formed in the steel pipe forming machine 30 extends in a direction orthogonal to the direction in which the corrugated steel plate 110 enters the steel pipe forming machine 30, and the cutter (not shown) is The extended steel pipe 120 is cut in the longitudinal direction.

The double structure using the corrugated steel sheet manufactured using the manufacturing method according to the present invention as described above, the steel pipe 130 is shown in Figs. 8 and 10, the mountains adjacent to each other in the width direction of the corrugated steel sheet 110. The first closed space 131 and the first closed space helically extended in the lengthwise direction are pressed in a direction in which the outwardly convex mountain and the inwardly convex mountain are adjacent to each other so that the 119 are in contact with each other so that the valleys 118 are closed. A second closed space 133 helically extending in the longitudinal direction is formed around the circumference 131.

The first closed space 131 and the second closed space 133 are formed at mutually intersecting positions from the center side of the steel pipe 130 in the radial direction, and are extended parallel to each other and rotated to pressurize the corrugated steel pipe 120. As shown in FIG. 9, the first pressing roller and the second pressing roller may have a rectangular shape.

In addition, the outer circumferential surface of the steel pipe 130 is formed as a smooth surface extending in the same line as the outer circumferential surface of the lock shim 125 is covered by the mutually contacting mountains 119.

The steel pipe 130 having a double structure using a corrugated steel plate according to an embodiment of the present invention is formed of a single corrugated steel plate 120, but has a double structure and is formed smoothly on the inside, so that the flow of fluid is easy. have.

In addition, since the steel pipe 130 having a double structure using a corrugated steel pipe according to an embodiment of the present invention is formed using a single corrugated steel plate, the manufacturing cost can be reduced, and the first closed space and the second closed space extending in the longitudinal direction Closed spaces are formed alternately and have high external pressure strength, and the interior is formed smoothly, so that fluid movement is smooth.

And, the manufacturing method of a steel pipe having a double structure using a corrugated steel pipe according to an embodiment of the present invention is formed by forming a tube having a double structure by forming a pipe having a double structure by forming a pipe having a double structure using a single corrugated steel plate, and the manufacturing cost is simplified. It is economical because it can be lowered, and there is an advantage that the first closed space and the second closed space are formed to be located alternately, so that the external pressure strength is high, and the inner circumferential surface is smoothly formed while the fluid moves smoothly.

In the steel pipe 130 having a double structure using a corrugated steel plate according to an embodiment of the present invention, the corrugated steel plate is wound so that the lock shim 125 is located inside and the side facing the outside is covered by the mutually contacting mountains 119 However, as another embodiment according to the present invention, as shown in Fig. 11, the steel pipe 230 having a double structure using a corrugated steel plate according to the present invention is a lock shim 125 The corrugated steel plate 120 is wound so as to be located on the outside and covers the inner side of the lock shim 123 so that the inner circumferential surface may be smoothly formed.

A method of manufacturing a steel pipe 230 having a double structure using a corrugated steel plate according to another embodiment of the present invention is a steel pipe such that the lock seam connection portions 104 and 105 of the corrugated steel plate 120 are positioned at the top in the corrugated steel sheet winding step (S6). Except for winding the corrugated steel sheet 120 while being placed on the molding machine 30, the method of manufacturing the steel pipe 230 having a double structure using the corrugated steel sheet according to an embodiment of the present invention is used.

That is, the steel pipe 230 having a dual structure using a corrugated steel plate according to another embodiment of the present invention is a corrugated steel plate 110 in a state in which the lock seam connection portions 113 and 114 of the corrugated steel plate 110 are positioned above the mountain. The lock shim 125 is positioned outside by winding and pressing through the first and second pressing rollers, and the inner circumferential surface thereof is formed smoothly by covering the inner side of the lock shim 125.

On the other hand, Figure 12 is a partial perspective view showing a state in which the uneven portion 201 is formed on the steel plate 100 in order to implement a steel pipe having a dual structure using a corrugated steel plate and a method for manufacturing the same according to another embodiment of the present invention. to be.

The steel pipe having a double structure using a corrugated steel plate according to another embodiment of the present invention is the same as the structure of the steel pipe 130 having a double structure using a corrugated steel plate according to an embodiment of the present invention, but irregularities are formed on both sides. have.

In addition, a method of manufacturing a steel pipe having a dual structure using a corrugated steel plate according to another embodiment of the present invention is a method of manufacturing a steel pipe having a dual structure using a corrugated steel plate according to an embodiment of the present invention. It further includes a molding step (not shown).

The step of forming the unevenness of the steel plate is a step of forming the unevenness of the steel plate 100 by passing the unevenness of the uncoiled steel sheet 100 to the unevenness forming unit 220 for forming.

The concave-convex forming unit 220 includes a first forming roller 221 and a second forming roller 225 overlapping vertically and rotating in opposite directions. The first forming roller 221 and the second forming roller 225 may be rotated by the conveying force of the steel plate. Alternatively, the uneven portion forming unit 220 is mounted on a forming roller support frame (not shown) that rotatably supports the first forming roller 221 and the second forming roller 225 and A first roller rotation motor (not shown) and a second roller rotation motor (not shown) for rotating the two forming roller 225 in the opposite direction may be provided.

The first forming roller 221 and the second forming roller 225 have irregularities 222 and 226 formed continuously on their outer circumferential surfaces. Each shape of the unevenness 222 of the first molding roller 221 and the unevenness 226 of the second molding roller 225 is the outer circumferential surface of the first molding roller 221 or the second molding roller 225 as shown. It may be formed by a plurality of ribs (203, 204, 227, 228) protruding and extending to cross each other, but is not limited thereto.

The steel plate 100 entered between the first forming roller 221 and the second forming roller 225 is pressed against the first forming roller 221 and the second forming roller 225 to have concave and convex shapes on both sides. The uneven portion 201 is formed.

A steel pipe having a double structure using a corrugated steel plate according to another embodiment of the present invention has uneven portions 201 formed on both sides, so that the peaks 119 and the valleys 118 of the corrugated steel plate are pressed in a direction adjacent to each other. Since friction between the mountains 119 that are in contact with each other in the width direction is improved, the external pressure strength may be improved.

Above, a steel pipe having a double structure using a corrugated steel sheet according to the present invention and a manufacturing method thereof have been described with reference to the embodiment shown in the drawings, but this is only exemplary, and those of ordinary skill in the art From this, it will be understood that various modifications and other equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical idea of the appended registration claims.

10: uncoiler 20: roll forming machine
21: first forming part 22: first upper forming roller
23: first lower forming roller 26: second forming part
27: second upper forming roller 28: second upper forming roller
30: corrugated steel pipe forming machine 33: upper lock seam roller
35: lower lock shim roller 100: steel plate
110: corrugated steel plate 120: corrugated steel pipe
125: Locksim
130: Steel pipe having a dual structure using corrugated steel plate
131: first closed space 133: second closed space
S1: Uncoiling step
S2: Corrugated steel sheet forming step
S3: Steel plate wave formation step
S4: Corrugated steel sheet curvature increasing step
S5: Corrugated steel pipe forming step
S6: Corrugated steel sheet winding step
S7: lock shim formation step
S8: Forming step of steel pipe with double structure
S9: Steel pipe cutting step

Claims (5)

An uncoiling step of unwinding the steel sheet wound on the uncoiler;
A corrugated steel sheet forming step of forming the unwound steel sheet into a corrugated steel sheet having a continuous corrugation of valleys and mountains and bending at both edges in the width direction in opposite directions to form a locking seam connection portion capable of being engaged with each other;
A corrugated steel pipe forming step of forming a corrugated steel pipe by forming a lock shim by pressing the lock shim connection portions which are in contact with each other while spirally winding the corrugated steel plate;
The first closed space spirally extended in the longitudinal direction by pressing the mountains formed on the outer circumferential surface of the corrugated steel pipe and the mountains formed on the inner circumferential surface to close the valleys by contacting the mountains adjacent to each other in the longitudinal direction of the corrugated steel pipe. A double structure steel pipe forming step of forming a steel pipe having a double structure in which a second closed space is formed spirally extending in a longitudinal direction at a position opposite to the first closed space;
A method of manufacturing a steel pipe having a double structure using a corrugated steel plate, comprising: a step of cutting the steel pipe into a predetermined length. The method of claim 1, wherein the corrugated steel sheet forming step
Including a step of increasing the curvature of the corrugated steel sheet so that the width of the open side of the corrugated steel sheet is narrower than the width of the closed side or the width of the lower end side of the mountain is narrower than the upper side. A method of manufacturing a steel pipe having a double structure using a corrugated steel plate as characterized. The method of claim 1,
Before the corrugated steel sheet forming step,
Method for manufacturing a steel pipe having a double structure using a corrugated steel sheet, characterized in that it further comprises a steel plate uneven forming step of forming an uneven portion on the outer circumferential surface of the unwinding steel sheet The corrugated steel plate is spirally wound so that the locking seam connection portions bent in opposite directions at both edges in the width direction of the corrugated steel plate with valleys and valleys are mutually engaged, and the locking seam connection portions that are mutually caught are pressed and formed through lock shims. The first in which the mountains formed on the outer circumferential surface and the mountains formed on the inner circumferential surface are pressed in a direction in which the mountains adjacent to each other in the width direction of the corrugated steel sheet are in contact with each other so that the valleys are closed. A closed space and a second closed space helically extending in the longitudinal direction are formed around the first closed space,
The corrugated steel sheet is
When the mountain formed on one side and the mountain formed on the other side are pressed in a direction adjacent to each other, the first closed space and the second closed space are formed, so that the width of the open side of the valley is greater than the width of the closed side. A steel pipe having a double structure using a corrugated steel plate, characterized in that it has a curvature of a narrower shape or a narrower width of the mountain than the upper portion.
The method of claim 4, wherein the corrugated steel sheet
Having a double structure using a corrugated steel plate, characterized in that the uneven portions are formed on both sides so that the mountain formed on one side and the mountain formed on the other side are pressed in a direction adjacent to each other to increase the frictional force between the mountains mutually in contact with each other in the width direction. Steel pipe.

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