Spiral pipe

Abstract

To provide a spiral pipe which is light-weight and achieves high mechanical strength.SOLUTION: A spiral pipe 1 has a spiral structure and includes: a main pipe part 10 which is formed by winding a belt-like metal plate 11 spirally and in which sides, which are located adjacent to each other in a spiral state, are joined; and a sub pipe part 20 in which a sheet 21 formed in a belt-like form by a fiber material is spirally wound around an outer peripheral surface of the main pipe part 10 so that the sides located adjacent to each other in the spiral state are overlapped and the sheet 21 is fastened to the main pipe part 10 by a synthetic resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spiral pipe having a helical structure. [Background technology]

[0002] In bridges, pipes for passing long materials such as water pipes and optical cables, and in ships, pipes for passing long materials and air, are preferably lightweight, but also require a certain level of mechanical strength. In particular, pipes arranged horizontally are subject to bending stress and therefore require high mechanical strength. For example, standardized metal pipes such as steel pipes, as this type of pipe, have a problem in that they cannot be made lightweight because their wall thickness is set. On the other hand, pipes made of a strip-shaped metal plate wound in a spiral shape can be made lightweight by setting the thickness of the metal plate, but there is a risk that sufficient mechanical strength cannot be obtained. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of the above circumstances, an object of the present invention is to provide a spiral pipe that is lightweight and has high mechanical strength. [Means for solving the problem]

[0004] In order to solve the above problems, the spiral pipe according to the present invention comprises: "It is a spiral pipe with a helical structure, a main pipe portion in which a strip-shaped metal plate is wound in a spiral shape, and adjacent sides of the main pipe portion are joined together in the spiral shape; a secondary pipe portion in which a sheet formed in a band shape from a fibrous material is wound in a spiral shape around the outer circumferential surface of the main pipe portion so that adjacent sides in the spiral shape overlap each other, and the sheet is fixed to the main pipe portion by a synthetic resin; "It is equipped with the following features."

[0005] The spiral pipe of this configuration comprises a main pipe section made of a metal plate and a secondary pipe section made of a sheet of fiber material and synthetic resin. Since the fiber material and synthetic resin that make up the secondary pipe section have a smaller specific gravity than metal, it can be made lighter than a pipe made of a metal plate wound in a spiral shape with a thickness that combines the thickness of the main pipe section and the thickness of the secondary pipe section.

[0006] According to this configuration, the secondary pipe portion fixed to the outer circumferential surface of the main pipe portion is made of a fiber material and a synthetic resin. That is, the secondary pipe portion is made of a fiber-reinforced resin. Since the fiber material has high strength (tensile strength, tensile modulus) in the longitudinal direction of the fiber, by spirally winding a sheet made of the fiber material, the longitudinal component of the fiber forming the sheet includes components in the axial direction of the spiral pipe and in the circumferential direction centered on the axial core of the spiral pipe, so that the mechanical strength of the secondary pipe portion is increased, and the mechanical strength of the main pipe portion can be reinforced by the secondary pipe portion. At this time, the sheet of the secondary pipe portion is wound in a state where adjacent sides overlap each other in a spiral shape, so that the outer circumferential surface of the main pipe portion is covered by the sheet without any gaps, and the entire main pipe portion can be reliably reinforced by the secondary pipe portion. As a result, the secondary pipe portion can reinforce the main pipe portion, and the mechanical strength can be increased compared to the case of only the main pipe portion.

[0007] In addition to the above configuration, the spiral pipe according to the present invention has the following features: "The sheet of the secondary pipe portion is The main pipe portion may be spirally wound in a direction opposite to the spiral direction of the main pipe portion.

[0008] According to this configuration, the sheet of the secondary pipe portion is made of carbon fiber. As described in detail below, carbon fiber has a higher specific tensile strength and specific tensile modulus than other fibers, so that the sheet can be made lighter and have higher mechanical strength than sheets made of glass fiber or other fibers.

[0009] In addition to the above configuration, the spiral pipe according to the present invention has the following features: "The sheet of the secondary pipe portion is The main pipe portion may be spirally wound in a direction opposite to the spiral direction of the main pipe portion.

[0010] According to this configuration, the belt-shaped sheet constituting the secondary pipe section is wound in the opposite direction to the spiral direction of the metal plate in the primary pipe section, so that the mechanical strength against internal pressure can be increased. More specifically, since the metal plate of the primary pipe section and the sheet of the secondary pipe section are each wound in a spiral shape, when the internal pressure tries to increase the inner diameter of the spiral pipe, a force acts on each of the metal plate and the sheet in a direction that unwinds the spiral. At this time, since the spiral directions of the metal plate and the sheet are opposite to each other, the forces acting on each act to cancel each other out, and the inner diameter is prevented from increasing. This allows the mechanical strength against internal pressure to be increased compared to when the metal plate and the sheet are each wound in a spiral shape in the same direction. Effect of the Invention

[0011] As described above, according to the present invention, a spiral pipe that is lightweight and has high mechanical strength can be provided. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a spiral pipe according to an embodiment of the present invention with a portion of a secondary pipe portion removed to expose a portion of a main pipe portion. FIG. [Diagram 2] 2 is an enlarged cross-sectional view of a main portion of the spiral pipe of FIG. 1 cut along a plane parallel to the axis thereof to show an enlarged view of a joint portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A spiral pipe 1 according to one embodiment of the present invention will be described in detail below with reference to the drawings. The spiral pipe 1 of this embodiment has a helical structure, and is used to protect long materials such as water pipes, optical cables, electric wires, communication lines, and gas pipes that are inserted through the spiral pipe. The spiral pipe 1 includes a cylindrical main pipe 10 formed by helically winding a strip-shaped metal plate 11, and a secondary pipe 20 that covers the outer circumferential surface of the main pipe 10. In FIG. 1, the secondary pipe 20 is shaded.

[0014] The main pipe 10 is formed by joining adjacent sides of the metal plate 11 in a spiral shape. More specifically, in the band-shaped metal plate 11, joints 11a and 11b are set within a range of a predetermined distance from each of a pair of sides extending in the longitudinal direction. For example, the joint 11a is folded back to the outside of a tube formed by the spiral, and the joint 11b is folded back to the inside of the tube, and the joint 11a of one of the adjacent sides and the joint 11b of the other side are engaged with each other and crimped (pressed together) to join the joints 11a and 11b to form a tube.

[0015] The secondary pipe 20 is composed of a sheet 21 formed in a band shape from a fiber material and a synthetic resin impregnated in the sheet 21. The sheet 21 is spirally wound around the outer circumferential surface of the main pipe 10 in a state where adjacent sides in the spiral state overlap each other in a reverse direction to the spiral direction of the main pipe 10. The sheet 21 is fixed to the main pipe 10 by the impregnated and hardened synthetic resin. The secondary pipe 20 may be formed by winding the sheet 21 around the main pipe 10 and then impregnating it with synthetic resin and hardening it, or may be formed by winding the sheet 21 impregnated with unhardened synthetic resin around the main pipe 10 and then hardening it.

[0016] Examples of the metal plate 11 constituting the main pipe portion 10 include a stainless steel plate, a galvanized steel plate, and an aluminum plate.

[0017] Examples of the fibers of the fiber material constituting the sheet 21 in the secondary pipe section 20 include carbon fiber, aramid fiber, ultra-high molecular weight polyethylene fiber, polyparaphenylene benzobis oxazole fiber (PBO fiber), high-strength polyarylate fiber, glass fiber, aluminum fiber, and titanium fiber. These fiber materials have high strength in the length direction of the fiber (tensile strength, tensile modulus). Table 1 shows the specific tensile strength and specific tensile modulus, which are the ratios of tensile strength and tensile modulus to the specific gravity, for the main fiber materials. In other words, the above fiber materials are lightweight yet have high mechanical strength. Examples of the fiber form when forming the sheet 21 include single wire, twisted wire, and parallel wire. Examples of the sheet 21 include woven fabric, nonwoven fabric, and unidirectional prepreg sheet in which the length direction of the fiber is unidirectionally impregnated with a curable resin and semi-cured. In the case of a unidirectional prepreg sheet, the curable resin serves both to bond the fibers together to form a sheet and to fix the sheet 21 to the main pipe section 10. Examples of the weaving method of the woven fabric include twill weave, plain weave, and satin weave.

[0018] [Table 1]

[0019] Examples of the synthetic resin that constitutes the secondary pipe portion 20 include epoxy resin, phenol resin, and polyester resin.

[0020] Incidentally, in this embodiment, the metal plate 11 of the main pipe section 10 is a stainless steel plate with a thickness of 0.5 mm and a width of 100 mm, and is wound in a spiral shape with a diameter of 200 mm, with a range of a predetermined distance from both sides (the width of each of the joints 11a and 11b) being 7.5 mm. The sheet 21 of the secondary pipe section 20 is made of 3K (3000 filament) carbon fiber twill weave, has a width of 100 mm, and is treated so that both ends do not unravel. The synthetic resin of the secondary pipe section 20 is a two-component epoxy resin, and FLOWRESS RESIN (registered trademark) is used. In this embodiment, the sheet 21 is wrapped around the main pipe section 10 with an overlap of 15 mm from the sides, and then coated with synthetic resin.

[0021] The spiral pipe 1 of this embodiment comprises a main pipe 10 made of a metal plate 11, and a secondary pipe 20 made of a sheet 21 formed of a fiber material and a synthetic resin. Since the fiber material and synthetic resin that make up the secondary pipe 20 have a smaller specific gravity than metal, it can be made lighter than a pipe made of a metal plate wound in a spiral shape with a thickness equal to the combined thickness of the main pipe 10 and the secondary pipe 20.

[0022] Furthermore, according to the spiral pipe 1 of this embodiment, the secondary pipe 20 fixed to the outer circumferential surface of the main pipe 10 is made of a fiber material and a synthetic resin. In other words, since the secondary pipe 20 is made of fiber-reinforced resin, the main pipe 10 can be reinforced by the secondary pipe 20. At this time, since the sheet 21 of the secondary pipe 20 is wound in a spiral shape with adjacent sides overlapping each other, the outer circumferential surface of the main pipe 10 is covered with the sheet 21 without any gaps, and the entire main pipe 10 can be reliably reinforced by the secondary pipe 20, and the mechanical strength is higher than that of the main pipe 10 alone.

[0023] More specifically, the fibers in the fiber material have a higher tensile strength in the length direction than the bending strength in the direction perpendicular to the length direction. In the present spiral pipe 1, the sheet 21 formed of the fiber material is wound in a spiral shape around the outer circumferential surface of the main pipe portion 10, so that the length direction of each fiber constituting the sheet 21 has a length component in the axial direction of the main pipe portion 10 and a length component in the circumferential direction. For example, when the present spiral pipe 1 is arranged horizontally and bending stress acts, the axial length of the part farther from the center of the arc of the arc-shaped curve on the outer circumferential surface of the spiral pipe 1 (here, the part facing downward) tends to become longer, so that tensile stress acts in the axial direction, and each fiber resists the tensile stress with its axial length component in its length direction. In addition, for example, when internal pressure acts on the present spiral pipe, the inner diameter of the spiral pipe tends to become larger, so that tensile stress acts in the circumferential direction, and each fiber resists the tensile stress with its circumferential length component in its length direction. In this way, the fiber material (fibers) of the sheet 21 constituting the secondary pipe section 20 resists the bending stress and internal pressure acting on the spiral pipe 1, so that the presence of the secondary pipe section 20 can reinforce the main pipe section 10 and increase the mechanical strength against bending stress, internal pressure, etc.

[0024] In addition, according to the spiral pipe 1 of this embodiment, the belt-like sheet 21 constituting the secondary pipe section 20 is wound in the opposite direction to the spiral direction of the metal plate 11 in the main pipe section 10, so that the strength against internal pressure can be increased. In detail, since the metal plate 11 of the main pipe section 10 and the sheet 21 of the secondary pipe section 20 are each wound in a spiral shape, when the internal pressure tries to increase the inner diameter of the spiral pipe 1, a force acts on each of the metal plate 11 and the sheet 21 in a direction that unwinds the spiral. At this time, since the spiral directions of the metal plate 11 and the sheet 21 are opposite to each other, the forces acting on each act to cancel each other out, and the inner diameter is prevented from increasing. As a result, the strength against internal pressure is increased compared to when the metal plate 11 and the sheet 21 are each wound in a spiral shape in the same direction. Therefore, when a long material such as a water pipe or optical cable is inserted into the spiral pipe 1 to protect it, the inserted long material comes into contact with the inner surface of the spiral pipe 1, and even if the load of the long material is applied to the inner surface and bending stress acts on the spiral pipe 1, the spiral pipe 1 is unlikely to bend.

[0025] Furthermore, since the spiral pipe 1 of this embodiment is difficult to bend as described above, the intervals between the attachment members for attaching the spiral pipe 1 to the bridge can be made longer than before. This makes it possible to reduce the number of attachment members compared to before, thereby suppressing increases in the cost of attachment to the bridge.

[0026] In addition, according to the spiral pipe 1 of this embodiment, a stainless steel plate is used for the main pipe portion 10, which has superior weather resistance, chemical resistance, rust resistance, strength, etc., and has a good balance with weight, compared to when an aluminum plate is used.

[0027] Furthermore, according to the spiral pipe 1 of this embodiment, the sheet 21 of the secondary pipe portion 20 is made of carbon fiber. As shown in Table 1, carbon fiber has a significantly higher specific tensile strength than other fibers, and a higher specific tensile modulus than other fibers. Therefore, compared to when the sheet 21 is made of other fibers such as glass fiber, it is possible to make it lighter and to increase the mechanical strength.

[0028] Furthermore, according to the spiral pipe 1 of this embodiment, a two-component epoxy resin, which is made by mixing a base resin and a hardener, is used as the synthetic resin for the secondary pipe section 20. This allows the resin to harden at room temperature, eliminating the need for equipment for heating and hardening the synthetic resin, and thus suppressing increases in manufacturing costs.

[0029] Furthermore, according to the spiral pipe 1 of this embodiment, the outer peripheral surface of the main pipe section 10 is covered by the secondary pipe section 20. Therefore, even if water leakage occurs at a joint in the main pipe section 10, the secondary pipe section 20 on the outside can prevent the water leakage, resulting in higher watertightness (airtightness) than when there is only the main pipe section 10.

[0030] Furthermore, according to the spiral pipe 1 of this embodiment, when forming the secondary pipe section 20, a strip-shaped sheet 21 is wound spirally around the outer peripheral surface of the main pipe section 10. This eliminates the need to prepare a large sheet corresponding to the length of the spiral pipe 1 or to wind multiple sheets, as compared to the case of winding a sheet in a circular ring shape, thereby suppressing increases in the costs of manufacturing the spiral pipe 1.

[0031] The present invention has been described above with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention, as described below.

[0032] For example, in the above embodiment, the main pipe portion 10 is formed by joining adjacent joint portions 11a, 11b together by crimping a strip-shaped metal plate in a spiral shape, but this is not limited to this, and the main pipe portion 10 may also be formed by joining the joints by welding such as continuous welding or spot welding.

[0033] In addition, in the above embodiment, the sheet 21 of the secondary pipe section 20 is wound spirally in the opposite direction to the spiral direction in which the metal plate 11 of the main pipe section 10 is wound, but this is not limited to this, and the sheet 21 may be wound spirally in the same direction as the spiral direction in which the metal plate 11 is wound.

[0034] In addition, in the above embodiment, the spiral pipe 1 is shown as being used to protect long materials such as water pipes and optical cables in bridges, but the present invention is not limited to this and may be used as a duct for intake and exhaust, air conditioning, etc. in ships, buildings, tunnels, etc., or as a pipe for water supply, drainage, gas, etc. [Explanation of symbols]

[0035] 1 Spiral Pipe 10 Main pipe section 11 Metal plate 11a Joint 11b Joint 20 Sub pipe section 21 sheets

Claims

1. A spiral pipe having a helical structure, a main pipe portion in which a strip-shaped metal plate is wound in a spiral shape, and adjacent sides of the main pipe portion are joined together in the spiral shape; a secondary pipe portion in which a sheet formed in a band shape from a fibrous material is wound in a spiral shape around the outer circumferential surface of the main pipe portion so that adjacent sides in the spiral shape overlap each other, and the sheet is fixed to the main pipe portion by a synthetic resin; A spiral pipe comprising:

2. The secondary pipe portion is The sheet is made of carbon fiber.

2. The spiral pipe according to claim 1 .

3. The sheet of the secondary pipe portion is The main pipe is wound in a spiral shape in a direction opposite to the spiral direction of the main pipe.

3. The spiral pipe according to claim 1 or 2.

Images