Composite pipe

Abstract

To provide a composite pipe of a novel structure which does not exist conventionally.SOLUTION: A composite pipe 1 includes a pipe body 11 as a water channel, a corrugated pipe 12 formed of a resin material to cover the outer periphery of the pipe body 11, and a coating pipe 14 arranged radially outward of the corrugated pipe 12 and formed of a resin material, the corrugated pipe 12 being formed in a bellows shape with crest parts 21 and trough parts 22 each of which has an outer diameter and an inner diameter smaller than those of the crest part 21 alternately provided in the axial direction, and so extendable in the axial direction, the coating pipe 14 being formed in a bellows shape with crest parts 31 and trough parts 32 each of which has an outer diameter and an inner diameter smaller than those of the crest part 31 alternately provided in the axial direction, and so extendable in the axial direction, independently from the corrugated pipe 12.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a composite pipe using a corrugated pipe. [Background technology]

[0002] Patent Documents 1 to 8 disclose corrugated pipes (coating layers) in which peaks and valleys are alternately formed in the axial direction. The corrugated pipes are made of a resin material such as low-density polyethylene, and are capable of expanding and contracting in the axial direction. A porous layer such as urethane foam is disposed on the inside of the corrugated pipe separately from the corrugated pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-219149 A [Patent Document 2] JP 2017-219150 A [Patent Document 3] JP 2018-105405 A [Patent Document 4] JP 2018-105406 A [Patent Document 5] JP 2019-105323 A [Patent Document 6] JP 2019-105328 A [Patent Document 7] JP 2019-215010 A [Patent Document 8] JP 2020-180627 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a composite pipe having a novel structure that has not existed in the past. [Means for solving the problem]

[0005] In order to achieve the above object, the composite pipe of the invention of claim 1 has an accordion-like shape in which crests and valleys, the outer diameter and inner diameter of which are smaller than those of the crests, are alternately arranged in the axial direction, and is capable of expanding and contracting in the axial direction, and comprises a corrugated pipe made of a resin material, a water-passing tubular body inserted into the corrugated pipe, and a coating layer made of a resin material and disposed radially outward on the corrugated pipe, wherein the coating layer has an accordion-like shape in which crests and valleys, the outer diameter and inner diameter of which are smaller than those of the crests, are alternately arranged in the axial direction, and is capable of expanding and contracting in the axial direction separately from the corrugated pipe.

[0006] The invention of claim 2 is similar to claim 1 in that the arrangement interval of the ridge portions of the coating pipe in the axial direction is the same as the arrangement interval of the ridge portions of the corrugated pipe, and the inner peripheral portion of the valley portions in the coating layer is located on the outer peripheral portion of the ridge portions of the corrugated pipe.

[0007] The invention of claim 3 is similar to claim 1 in that the arrangement interval of the ridge portions of the coating pipe in the axial direction is the same as the arrangement interval of the ridge portions of the corrugated pipe, and the inner peripheral portion of the valley portion of the coating layer is located at the valley portion of the corrugated pipe. Effect of the Invention

[0008] The composite pipe of the present invention is novel. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a half cross-sectional view showing a composite pipe. [Diagram 2] FIG. 1 is a schematic diagram showing a manufacturing apparatus for a composite pipe. [Diagram 3] FIG. 4 is a half cross-sectional view showing another example of a composite pipe. [Figure 4] FIG. 4 is a schematic diagram showing another example of a composite pipe manufacturing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described in which the present invention is embodied in a composite pipe for supplying hot and cold water. As shown in FIG. 1, a compound pipe 1 includes a pipe body 11 as a water passage, and a corrugated pipe 12 as a protective pipe covering the outer periphery of the pipe body 11.

[0011] The pipe body 11 is made of a resin material. Examples of the resin material include polyolefins such as polybutene, polyethylene, cross-linked polyethylene, and polypropylene, as well as vinyl chloride. Only one of these resin materials may be used, or two or more of them may be used in combination. The resin material constituting the pipe body 11 may contain other additives. In this embodiment, the pipe body 11 is made of cross-linked polyethylene. The pipe body 11 has a nominal diameter of 13A.

[0012] The corrugated pipe 12 has a bellows shape in which peaks 21 and valleys 22, each of which has an outer diameter and an inner diameter smaller than those of the peaks 21, are alternately arranged in the axial direction (the left-right direction in FIG. 1), and is capable of expanding and contracting in the axial direction. The vertical cross-sectional area of ​​the peaks 21 is larger than that of the valleys 22.

[0013] The corrugated pipe 12 is made of a resin material. Examples of the resin material include polyurethane, polystyrene, polyethylene, polypropylene, ethylene propylene diene rubber, and mixtures thereof. The resin material may contain other additives.

[0014] The corrugated pipe 12 is made of a porous foamed resin of the closed-cell type or open-cell type (cells are indicated by "K"). If it is the closed-cell type, the corrugated pipe 12 has excellent heat insulation and shock absorption properties. If it is the open-cell type, the corrugated pipe 12 has excellent shrinkage properties and excellent sound absorption properties for water hammer sounds and the like generated in the pipe body 11.

[0015] In this embodiment, the corrugated pipe 12 is made of closed-cell foamed polyethylene. A coloring agent is added to the resin material constituting the corrugated pipe 12. The coloring agent causes the corrugated pipe 12 to be colored blue, which is suitable for a composite pipe 1 for water supply, red, which is suitable for a composite pipe 1 for hot water supply, or white, which is common for composite pipes 1 used for connecting to equipment such as water heaters. The corrugated pipe 12 has a porous layer visible from the outer surface side, so that it has a mottled color and no gloss, and therefore has excellent color compatibility with the surrounding colors of the construction site.

[0016] The corrugated pipe 12 is composed only of a porous layer. Therefore, the corrugated pipe 12 has a porous layer exposed radially outward (outer surface) and also exposed radially inward (inner surface). Therefore, a person handling the composite pipe 1 comes into direct contact with the porous layer of the corrugated pipe 12, and the unevenness of the porous layer makes it difficult to slip, making it easy to handle. In addition, the pipe body 11 comes into direct contact with the porous layer of the corrugated pipe 12, and the contact area is small, making it easy to slide against the corrugated pipe 12, making it easy to perform an operation such as contracting the corrugated pipe 12 to expose the pipe body 11.

[0017] Next, a manufacturing apparatus 40 for the composite pipe 1 of this embodiment will be described. 2, the manufacturing device 40 manufactures the composite pipe 1 by moving the pipe body 11 from the left side to the right side of the drawing and forming the corrugated pipe 12 around the outer periphery of the pipe body 11. This manufacturing method is called in-line molding.

[0018] The manufacturing apparatus 40 includes a payout machine 41, an extruder 42, a cross die 43, a corrugator 44, a cooling tank 45, and a take-up machine 46. The payout machine 41 pays out the tube 11 toward the cross die 43. The extruder 42 extrudes a molten resin material toward the cross die 43 to form the corrugated tube 12. A foaming agent that promotes a foaming reaction of the resin material is injected or kneaded into the resin material. As the foaming agent, a chemical foaming agent or a physical foaming agent may be used. Alternatively, a chemical foaming agent and a physical foaming agent may be used in combination as the foaming agent.

[0019] In this embodiment, low-density polyethylene is used as the main resin material (principal material) for forming the corrugated pipe 12, and polystyrene (foaming agent master batch) containing a foaming agent such as butane or pentane, and a color master batch containing a blue pigment as a coloring agent are mixed with the resin material. The mass ratio of the main material to the foaming agent master batch and the color master batch is 100:5:5.

[0020] When the tube 11 passes through the cross die 43, the resin material is extruded in a cylindrical shape onto the outer periphery of the tube 11. As a result, a resin material covering the outer periphery of the tube 11 is formed.

[0021] The corrugator 44 has a known configuration for circulating a mold block (metal mold) not shown. When the pipe body 11 covered with the resin material passes through the corrugator 44, the resin material foams and deforms along the shape of the mold block, forming a bellows-like corrugated pipe 12 in which peaks 21 and valleys 22 are alternately provided in the axial direction. Since the corrugated pipe 12 is porous, the contact area with the pipe body 11 can be reduced, and the hot corrugated pipe 12 can be prevented from sticking to the pipe body 11. This is particularly effective in realizing in-line molding of the composite pipe 1.

[0022] In this embodiment, of the resin materials for forming the corrugated pipe 12, the resin material located at the peaks 21 has an expansion ratio of 2.2, and the resin material located at the valleys 22 has an expansion ratio of 1.4. In other words, of the resin materials for forming the corrugated pipe 12, the resin material located at the peaks 21 has a higher expansion ratio than the resin material located at the valleys 22.

[0023] If the foaming ratio of the resin material used to form the corrugated pipe 12 is low, the difference in inner diameter between the peaks 21 and the valleys 22 becomes clear; in other words, the bellows shape on the inner surface of the corrugated pipe 12 becomes clear, so that the elasticity of the corrugated pipe 12 can be well maintained, and there is little difference in appearance from conventional (non-foamed) corrugated pipes, making it feel natural.

[0024] In order to achieve such an expanded state, of the resin materials for forming the corrugated pipe 12, the resin material located at the peaks 21 preferably has an expansion ratio of 2.0 to 2.4 times, more preferably 2.1 to 2.3 times, and the resin material located at the valleys 22 preferably has an expansion ratio of 1.2 to 1.6 times, more preferably 1.3 to 1.5 times.

[0025] Now, the pipe body 11 and the corrugated pipe 12 that have passed through the corrugator 44 are cooled as they pass through the cooling tank 45. This causes the corrugated pipe 12 to harden, and the composite pipe 1 is formed. The formed composite pipe 1 is taken up by a take-up machine 46 and wound up by a winding machine (not shown).

[0026] (Example of change) The above embodiment may be modified as follows. In the corrugated pipe 12, the porous layer is exposed only on the inner side of the outer and inner sides in the radial direction. In other words, a coating layer made of a resin material is disposed on the outer side in the radial direction of the corrugated pipe 12.

[0027] For example, in the composite pipe 2 shown in Figure 3, the coating layer 14 of the coating pipe has a bellows shape in which ridges 31 and valleys 32, each of which has an outer diameter and an inner diameter smaller than those of the ridges 31, are alternately arranged in the axial direction (the left-right direction in Figure 3), and the coating pipe 14 is capable of expanding and contracting in the axial direction.

[0028] The arrangement interval of the peaks 31 in the axial direction may be the same as the arrangement interval of the peaks 21 of the corrugated pipe 12 as shown in Fig. 3, or may be different as shown in Fig. 3. Moreover, the covering pipe 14 may be non-porous as shown in Fig. 3, or may be porous as shown in Fig. 3. Furthermore, the inner peripheral portion of the valleys 32 of the covering pipe 14 may be located on the outer periphery of the peaks 21 of the corrugated pipe 12 as shown in Fig. 3, or may be located in the valleys 22 of the corrugated pipe 12 as shown in Fig. 3, or may even extend into the valleys 22 as shown in Fig. 3.

[0029] Since the configuration of the composite pipe 2 other than the cladding pipe 14 is the same as that of the composite pipe 1 shown in FIG. 1, the same components are designated by the same reference numerals and the description thereof will be omitted.

[0030] To manufacture the composite pipe 2, for example, a manufacturing apparatus 50 shown in Fig. 4 is used. In the manufacturing apparatus 50, a separate cross die 51 is disposed between the cooling tank 45 and the take-up machine 46 in the manufacturing apparatus 40 shown in Fig. 2. A separate extruder 52 extrudes a molten resin material (polyethylene in this embodiment) for forming the covering pipe 14 toward the cross die 51. When the tube body 11 and the corrugated pipe 12 pass through the cross die 51, the cross die 51 extrudes the resin material in a cylindrical shape onto the outer periphery of the corrugated pipe 12. As a result, a resin material covering the outer periphery of the corrugated pipe 12 is formed.

[0031] Another corrugator 53 is disposed between the cross die 51 and the take-off machine 46. When the corrugated pipe 12 covered with the resin material passes through the corrugator 53, the resin material covering the outer periphery of the corrugated pipe 12 is deformed along the shape of the mold block, and a bellows-shaped covering pipe 14 in which peaks 31 and valleys 32 are alternately provided in the axial direction is formed.

[0032] Another cooling tank 54 is disposed between the corrugator 53 and the take-up machine 46. The pipe body 11, the corrugated pipe 12, and the cladding pipe 14 are cooled while passing through the cooling tank 54. As a result, the cladding pipe 14 hardens, and the composite pipe 2 is formed.

[0033] In the corrugated pipe 12, the porous layer is exposed only on the outer side of the radially outer and inner sides. In other words, by disposing an intermediate layer on the radially inner side of the corrugated pipe 12, the porous layer of the corrugated pipe 12 does not come into direct contact with the pipe body 11.

[0034] The intermediate layer may be a foam layer or a film layer. In particular, in order to prevent the high-temperature resin material forming the corrugated pipe 12 from adhering to the pipe body 11, it is preferable to use a layer having an effect of suppressing the adhesion for the intermediate layer.

[0035] In the corrugated pipe 12, the porous layer is not exposed both radially outward and radially inward. In other words, in the corrugated pipe 12, a coating layer is disposed radially outward and an intermediate layer is disposed radially inward.

[0036] In the above embodiment, the composite pipe 1 is formed by forming the corrugated pipe 12 on the outer circumferential surface of the pipe body 11 by so-called in-line molding. However, this can be changed so that the composite pipe 1 is manufactured by forming only the corrugated pipe 12 by the corrugator 44, and then inserting the pipe body 11 into the corrugated pipe 12 in a subsequent pipe passing process. Even in this case, the pipe body 11 comes into direct contact with the porous layer of the corrugated pipe 12, so that the pipe body 11 slides smoothly against the corrugated pipe 12, and the pipe body 11 can be easily inserted into the corrugated pipe 12.

[0037] Of the resin materials used to form the corrugated pipe 12, the foaming ratio of the resin material located at the peaks 21 is set to be lower than the foaming ratio of the resin material located at the valleys 22.

[0038] This can be realized in a corrugated pipe 12 corresponding to a pipe body 11 having a nominal diameter of 16A. In this case, among the resin materials for forming the corrugated pipe 12, the resin material located at the peaks 21 may have an expansion ratio of 1.7 times, and the resin material located at the valleys 22 may have an expansion ratio of 1.1 times.

[0039] If the foaming ratio of the resin material used to form the corrugated pipe 12 is low, the difference in inner diameter between the peaks 21 and the valleys 22 becomes clear; in other words, the bellows shape on the inner surface of the corrugated pipe 12 becomes clear, so that the elasticity of the corrugated pipe 12 can be well maintained, and there is little difference in appearance from conventional (non-foamed) corrugated pipes, making it feel natural.

[0040] In order to achieve such an expanded state, of the resin materials for forming the corrugated pipe 12, the resin material located at the peaks 21 preferably has an expansion ratio of 1.5 to 1.9 times, more preferably 1.6 to 1.8 times, and the resin material located at the valleys 22 preferably has an expansion ratio of 1.05 to 1.15 times, more preferably 1.075 to 1.125 times.

[0041] (Additional Note) The technical ideas that can be understood from the above embodiment will be described. (1) A composite pipe in which a water-passing pipe is inserted into the corrugated pipe according to claim 1, wherein a coating layer is formed on the outer periphery of the corrugated pipe, and the coating layer is an accordion-shaped coating pipe in which peaks and valleys having an outer diameter and an inner diameter smaller than those of the peaks are alternately arranged in the axial direction, and the coating pipe is capable of expanding and contracting in the axial direction.

[0042] (2) The corrugated pipe according to claim 1, wherein the porous layer is made of a low foaming resin.

[0043] (3) A corrugated pipe as described in claim 1 or technical idea (2) having uneven color shading.

[0044] (4) The corrugated pipe according to technical idea (2), wherein the porous layer has an expansion ratio of the peaks higher than that of the valleys, making the peaks of the corrugated pipe less slippery when directly touched by a person handling the composite pipe, and making the composite pipe easier to handle.

[0045] (5) A corrugated pipe according to technical idea (2), in which the porous layer has an expansion ratio at the peaks lower than that at the valleys. In a composite pipe using such a corrugated pipe, the contact area between the valleys of the corrugated pipe and a pipe body can be narrowed, improving the sliding of the pipe body relative to the corrugated pipe and facilitating, for example, the task of contracting the corrugated pipe to expose the pipe body. [Explanation of symbols]

[0046] 1…Composite pipe 2…Composite pipe 11...Body 12...Corrugated pipe 14…cladding tube 21…Yamabe 22. Valley 31…Yamabe 32…Valley 40...Manufacturing equipment 41...Payloader 42…Extruder 43…Cross Die 44…Corrugator 45...Cooling tank 46...Removal machine 50...Manufacturing equipment 51...Cross Die 52...Extruder 53…Corrugator 54…Cooling tank

Claims

1. a corrugated pipe made of a resin material, the corrugated pipe having a bellows shape in which peaks and valleys having an outer diameter and an inner diameter smaller than those of the peaks are alternately provided in an axial direction, the corrugated pipe being expandable and contractible in the axial direction; A water-passing pipe inserted into the corrugated pipe; a coating layer disposed radially outward of the corrugated pipe and made of a resin material; A composite pipe comprising: The coating pipe serving as the coating layer is a bellows-shaped composite pipe in which peaks and valleys, each of which has an outer diameter and an inner diameter smaller than those of the peaks, are arranged alternately in the axial direction, and which is capable of expanding and contracting in the axial direction independently of the corrugated pipe.

2. 2. The compound pipe according to claim 1, wherein an arrangement interval of the ridge portions of the covering pipe in the axial direction is the same as an arrangement interval of the ridge portions of the corrugated pipe, and an inner peripheral portion of the valley portion of the covering layer is located on an outer peripheral portion of the ridge portions of the corrugated pipe.

3. 2. The compound pipe according to claim 1, wherein an arrangement interval of the crest portions of the covering pipe in the axial direction is the same as an arrangement interval of the crest portions of the corrugated pipe, and an inner peripheral portion of the valley portion of the covering layer is located at the valley portion of the corrugated pipe.

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