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

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[0005] To achieve the above objective, the composite pipe of the invention of claim 1 comprises a corrugated pipe made of a resin material, having a bellows-like shape in which peaks and valleys having smaller outer and inner diameters than the peaks are alternately provided in the axial direction, and being expandable and contractible in the axial direction; a water-conducting pipe inserted into the corrugated pipe; and a coating layer made of a resin material, arranged radially outward in the corrugated pipe, wherein the coating pipe as the coating layer has a bellows-like shape in which peaks and valleys having smaller outer and inner diameters than the peaks are alternately provided in the axial direction, and is expandable and contractible in the axial direction independently of the corrugated pipe.

[0006] The invention of claim 2 is as described in claim 1, wherein the spacing of the peaks in the axial direction of the coating tube is the same as the spacing of the peaks of the corrugated pipe, and the inner circumference of the valleys in the coating layer is located on the outer circumference of the peaks of the corrugated pipe.

[0007] The invention of claim 3 is as described in claim 1, wherein the spacing of the peaks in the axial direction of the cladding tube is the same as the spacing of the peaks of the corrugated pipe, and the inner circumference portion of the valleys in the cladding layer is located in the valleys of the corrugated pipe. [Effects of the Invention]

[0008] The composite pipe of the present invention is novel. [Brief explanation of the drawing]

[0009] [Figure 1] A half-section view showing a composite pipe. [Figure 2] A schematic diagram showing the manufacturing equipment for composite pipes. [Figure 3] A half-section diagram showing another example of a composite pipe. [Figure 4] A schematic diagram showing a manufacturing apparatus for a composite pipe, as in another example. [Modes for carrying out the invention]

[0010] One embodiment of the present invention, implemented in a composite pipe for water supply and hot water supply, will be described. As shown in Figure 1, the composite pipe 1 comprises a pipe body 11 as a waterway and a corrugated pipe 12 as a protective pipe that covers the outer circumference of the pipe body 11.

[0011] The pipe body 11 is made of a resin material. Examples of such resin materials include polyolefins such as polybutene, polyethylene, crosslinked polyethylene, and polypropylene, as well as vinyl chloride. Only one of these resin materials may be used, or two or more 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 crosslinked polyethylene. The pipe body 11 has a nominal diameter of 13A.

[0012] The corrugated pipe 12 has a bellows-like structure with alternating peaks 21 and valleys 22, each with a smaller outer and inner diameter than the peaks 21, arranged in the axial direction (left-right direction in Figure 1), allowing for expansion and contraction in the axial direction. The longitudinal cross-sectional area of ​​the peaks 21 is larger than the longitudinal cross-sectional area of ​​the valleys 22.

[0013] The corrugated tube 12 is made of a resin material. Examples of such resin materials include polyurethane, polystyrene, polyethylene, polypropylene, and ethylene propylene diene rubber, as well as mixtures thereof. The resin material may also contain other additives.

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

[0015] In addition, in this embodiment, the corrugated tube 12 is made of foamed polyethylene of the closed-cell type. Further, a coloring agent is added to the resin material constituting the corrugated tube 12. Due to the coloring agent, the corrugated tube 12 is colored blue suitable for the composite pipe 1 for water supply, red suitable for the composite pipe 1 for hot water supply, or white which is common for the composite pipe 1 used for connection to devices such as water heaters. The corrugated tube 12 has a porous layer visible from the outer surface side, resulting in uneven shades of color and no gloss, and is excellent in color compatibility with the colors around the construction location.

[0016] The corrugated tube 12 is composed only of the porous layer. Therefore, the porous layer is exposed on the outer side (outer surface) in the radial direction and the porous layer is also exposed on the inner side (inner surface) in the radial direction of the corrugated tube 12. Thus, a person handling the composite pipe 1 comes into direct contact with the porous layer of the corrugated tube 12, and due to the unevenness of the porous layer, it is difficult to slip and easy to handle. Also, since the pipe body 11 comes into direct contact with the porous layer of the corrugated tube 12, the contact area is small and the slipperiness with respect to the corrugated tube 12 is good. For example, the operation of shrinking the corrugated tube 12 to expose the pipe body 11 becomes easy.

[0017] Next, the manufacturing apparatus 40 for the composite pipe 1 of this embodiment will be described. As shown in FIG. 2, the manufacturing apparatus 40 manufactures the composite pipe 1 by forming the corrugated tube 12 on the outer circumference of the pipe body 11 while moving the pipe body 11 from the left side to the right side of the drawing. This manufacturing method is called in-line molding.

[0018] The manufacturing apparatus 40 comprises a feeder 41, an extruder 42, a cross die 43, a corrugator 44, a cooling tank 45, and a take-up machine 46. The feeder 41 feeds the pipe body 11 toward the cross die 43. The extruder 42 extrudes molten resin material toward the cross die 43 to form the corrugated pipe 12. The resin material is injected or mixed with a blowing agent to promote the foaming reaction of the resin material. A chemical blowing agent or a physical blowing agent may be used as the blowing agent. Alternatively, a chemical blowing agent and a physical blowing agent may be used in combination.

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

[0020] As the tube 11 passes through the cross die 43, the cross die 43 extrudes the resin material in a cylindrical shape toward the outer circumference of the tube 11. This forms a resin material that covers the outer circumference of the tube 11.

[0021] The corrugator 44 has a well-known configuration for circulating a mold block (mold) (not shown). As the tube 11 covered with the resin material passes through the corrugator 44, the resin material foams and deforms along the mold shape of the mold block, forming a bellows-shaped corrugated tube 12 with alternating peaks 21 and valleys 22 in the axial direction. Because the corrugated tube 12 is porous, the contact area with the tube 11 can be reduced, and the high temperature corrugated tube 12 can be prevented from sticking to the tube 11. This is particularly effective in realizing in-line molding of the composite tube 1.

[0022] In this embodiment, among the resin materials used to form the corrugated pipe 12, the resin material located at the peaks 21 has an expansion ratio of 2.2 times, while the resin material located at the valleys 22 has an expansion ratio of 1.4 times. In other words, among the resin materials used to form 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-like shape on the inner surface of the corrugated pipe 12 becomes clear, which allows the expansion and contraction of the corrugated pipe 12 to be maintained well, and the appearance is less different from conventional (non-foamed) corrugated pipes, so there is no sense of incongruity.

[0024] In order to achieve this foamed state, among the resin materials used to form the corrugated pipe 12, the foaming ratio of the resin material located in the peaks 21 is preferably 2.0 to 2.4 times, more preferably 2.1 to 2.3 times, and the foaming ratio of the resin material located in the valleys 22 is preferably 1.2 to 1.6 times, more preferably 1.3 to 1.5 times.

[0025] Now, the pipe body 11 and corrugated pipe 12 that have passed through the corrugator 44 are cooled as they pass through the cooling tank 45. As a result, the corrugated pipe 12 hardens and a composite pipe 1 is formed. The formed composite pipe 1 is taken up by the 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 radially outer side. In other words, a coating layer made of resin material is placed on the radially outer side of the corrugated pipe 12.

[0027] For example, in the composite pipe 2 shown in Figure 3, the coating pipe 14, which serves as the coating layer, has a bellows-like shape in which peaks 31 and valleys 32, each with a smaller outer and inner diameter than the peaks 31, are alternately arranged in the axial direction (left-right direction in Figure 3), allowing for expansion and contraction in the axial direction.

[0028] The spacing of the peaks 31 in the axial direction may be the same as the spacing of the peaks 21 of the corrugated pipe 12, as shown in Figure 3, or it may be different, although this is not shown. Also, the cladding pipe 14 may not be porous, as shown in Figure 3, or it may be porous, although this is not shown. Furthermore, the inner circumference of the valleys 32 in the cladding pipe 14 may be located on the outer circumference of the peaks 21 of the corrugated pipe 12, as shown in Figure 3, or it may be located in the valleys 22 of the corrugated pipe 12, or it may even extend into the valleys 22, although this is not shown.

[0029] In addition, since the components of composite pipe 2 other than the cladding pipe 14 are the same as those of composite pipe 1 shown in Figure 1, the same component numbers are assigned to identical components and their explanations are omitted.

[0030] For the manufacture of the composite pipe 2, for example, the manufacturing apparatus 50 shown in Figure 4 is used. In the manufacturing apparatus 50, a separate cross die 51 is positioned between the cooling tank 45 and the take-up machine 46 in the manufacturing apparatus 40 shown in Figure 2. Another extruder 52 extrudes molten resin material (polyethylene in this embodiment) toward the cross die 51 to form the coated pipe 14. As the pipe 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 toward the outer circumference of the corrugated pipe 12. This forms a resin material that covers the outer circumference of the corrugated pipe 12.

[0031] A separate corrugator 53 is positioned between the cross die 51 and the take-up machine 46. As the corrugated pipe 12 covered with the resin material passes through the corrugator 53, the resin material covering the outer circumference of the corrugated pipe 12 is deformed to conform to the mold shape of the mold block, forming a bellows-shaped covering pipe 14 with alternating peaks 31 and valleys 32 in the axial direction.

[0032] A separate cooling tank 54 is positioned between the corrugator 53 and the take-up machine 46. The pipe body 11, corrugated pipe 12, and cladding pipe 14 are cooled as they pass through the cooling tank 54. This causes the cladding pipe 14 to harden, forming the composite pipe 2.

[0033] ○ In the corrugated pipe 12, the porous layer is exposed only on the outer side of the radially outward and inward sides. In other words, by placing an intermediate layer radially inward in 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 foamed layer or a film layer. In particular, it is preferable to use an intermediate layer that has an effect of suppressing adhesion in order to prevent the high-temperature resin material forming the corrugated tube 12 from adhering to the tube body 11.

[0035] ○ In the corrugated pipe 12, the porous layer should not be exposed on either the radially outward or radially inward side. In other words, in the corrugated pipe 12, the coating layer should be placed on the radially outward side, and the intermediate layer should be placed on the radially inward side.

[0036] In the above embodiment, the composite pipe 1 was formed by molding a corrugated pipe 12 onto the outer surface of a pipe body 11 by so-called in-line molding. This was changed to a method in which only the corrugated pipe 12 is molded in a corrugator 44, and then the pipe body 11 is inserted into the corrugated pipe 12 in a subsequent pipe-fitting process to manufacture the composite pipe 1. In this case as well, since the pipe body 11 is in direct contact with the porous layer of the corrugated pipe 12, the sliding of the pipe body 11 against the corrugated pipe 12 is improved, making it easier to insert the pipe body 11 into the corrugated pipe 12.

[0037] ○ The foaming ratio of the resin material located at the peaks 21 of the corrugated pipe 12 is made lower than that of the resin material located at the valleys 22.

[0038] This should be implemented in a corrugated pipe 12 corresponding to a pipe body 11 with a nominal diameter of 16A. In this case, the resin material used to form the corrugated pipe 12 should have an expansion ratio of 1.7 times for the resin material located in the peaks 21 and an expansion ratio of 1.1 times for the resin material located in the valleys 22.

[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-like shape on the inner surface of the corrugated pipe 12 becomes clear, which allows the expansion and contraction of the corrugated pipe 12 to be maintained well, and the appearance is less different from conventional (non-foamed) corrugated pipes, so there is no sense of incongruity.

[0040] In order to achieve this foamed state, among the resin materials used to form the corrugated pipe 12, the foaming ratio of the resin material located in the peaks 21 is preferably 1.5 to 1.9 times, and more preferably 1.6 to 1.8 times, while the foaming ratio of the resin material located in the valleys 22 is preferably 1.05 to 1.15 times, and more preferably 1.075 to 1.125 times.

[0041] (Note) The technical concepts that can be understood from the above embodiments are described below. (1) A composite pipe having a water-conducting pipe body inserted through a corrugated pipe as described in claim 1, wherein a coating layer is formed on the outer circumference of the corrugated pipe, and the coating layer is a bellows-shaped coating pipe having alternating peaks and valleys in the axial direction, with the outer diameter and inner diameter being smaller than the peaks, respectively, and the coating pipe is a composite pipe that can expand and contract 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) Corrugated pipe according to claim 1 or technical idea (2), wherein the color intensity is uneven.

[0044] (4) The porous layer is a corrugated pipe as described in technical concept (2), wherein the foaming ratio of the peaks is higher than that of the valleys. In this way, the peaks of the corrugated pipe that are directly in contact with the person handling the composite pipe become less slippery, making it easier to handle the composite pipe.

[0045] (5) The corrugated pipe described in technical concept (2), wherein the porous layer has a lower foaming ratio in the peaks than in the valleys. In a composite pipe using such a corrugated pipe, the contact area between the valleys of the corrugated pipe and the pipe body can be reduced, the sliding of the pipe body against the corrugated pipe is improved, and for example, the work of shrinking the corrugated pipe to expose the pipe body becomes easier. [Explanation of Symbols]

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

Claims

[Claim 1] A corrugated tube made of resin material has a bellows-like shape in which peaks and valleys, each with a smaller outer and inner diameter than the peaks, are alternately arranged in the axial direction, and which can be expanded and contracted by hand in the axial direction, A water-conducting pipe inserted into the aforementioned corrugated pipe, In the corrugated pipe, a coating layer made of resin material is arranged radially outward. A composite pipe comprising, The coating tube, which serves as the coating layer, has a bellows-like shape in which peaks and valleys, each having a smaller outer and inner diameter than the peaks, are alternately arranged in the axial direction. The corrugated pipe is a composite pipe in which the corrugated pipe can be expanded and contracted in the axial direction independently of the corrugated pipe by a person, such that the corrugated pipe does not have a ridge on the back side of the ridge of the corrugated pipe, and the corrugated pipe does not have a valley on the back side of the valley of the corrugated pipe.

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