Composite pipe

Abstract

To enhance the degree of adhesion between a base pipe and a coating layer constituting a corrugated pipe.SOLUTION: A composite pipe 10 includes a pipe body 11, and a corrugated pipe 12 covering the outer periphery of the pipe body 11, the corrugated pipe 12 having a base pipe 20 formed of a resin material, and a covering layer 30 formed of a resin material to coat the outer peripheral face pf the base pipe 20, the base pipe 20 being formed in a bellows shape with crest parts 21 and a trough parts 22 each of which has an outer diameter smaller than that of the crest part 21 provided alternately in the axial direction of the base pipe 20. Between the corner of the trough part 22 and the coating layer 30, an air layer S is formed.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, there is a composite pipe that includes a pipe body and a corrugated pipe that covers the outer periphery of the pipe body (see, for example, Patent Document 1). The corrugated pipe has a base pipe made of a resin material and a coating layer that is also made of a resin material and coats the outer periphery of the base pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] 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. [Means for solving the problem]

[0005] A composite pipe for achieving the above-mentioned object comprises a pipe body and a corrugated pipe covering the outer periphery of the pipe body, the corrugated pipe having a base pipe made of a resin material and a coating layer made of a resin material and thinner than the base pipe that covers the outer periphery of the base pipe, the base pipe being bellows-shaped in which peaks and valleys having an outer diameter smaller than the peaks are alternately arranged in the axial direction of the base pipe, and an air layer is formed between the corners of the valleys and the coating layer.

[0006] In addition, a composite pipe for achieving the above-mentioned object comprises a pipe body and a corrugated pipe covering the outer periphery of the pipe body, the corrugated pipe having a base pipe made of a resin material and a coating layer made of a resin material and thinner than the base pipe that covers the outer periphery of the base pipe, the base pipe having a bellows shape in which peaks and valleys having an outer diameter smaller than the peaks are alternately arranged in the axial direction of the base pipe, and an air layer is formed only between the corners of the valleys and the coating layer between the valleys and the coating layer, and there are portions between the valleys and the coating layer where no air layer is formed. Effect of the Invention

[0007] According to the present invention, a composite pipe having a novel structure can be obtained. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view showing a composite pipe according to one embodiment. [Diagram 2] FIG. 2 is a half cross-sectional view showing the composite pipe of the embodiment. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing a part of FIG. 2. [Figure 4] Cross-sectional view taken along line 4-4 in Figure 2. [Diagram 5] FIG. 2 is a schematic diagram showing a manufacturing apparatus for a composite pipe according to the embodiment. [Figure 6] FIG. 2 is a plan view showing a molding surface of a die of the corrugator according to the embodiment. [Figure 7] FIG. 4 is a half cross-sectional view showing a connecting pipe passing through a corrugator. [Figure 8] 4 is a half cross-sectional view showing how a coating layer is formed on the outer circumferential surface of a connecting pipe. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment will be described with reference to FIGS. First, the structure of the composite pipe 10 will be described. As shown in FIGS. 1 to 4, a composite pipe 10 includes a pipe body 11 and a corrugated pipe 12 that covers the outer periphery of the pipe body 11.

[0010] The tube 11 is made of a resin material. Examples of the resin material constituting the tube body 11 include polyolefins such as polybutene, polyethylene, cross-linked polyethylene, and polypropylene, and vinyl chloride. The above-mentioned resin materials may be used alone or in combination of two or more. The resin material constituting the tube body 11 may also contain other additives.

[0011] The pipe body 11 in this embodiment is made of cross-linked polyethylene. The corrugated pipe 12 has a base pipe 20 made of a resin material, and a coating layer 30 made of a resin material and coating the outer circumferential surface of the base pipe 20 .

[0012] The connecting pipe 20 has a bellows shape in which peaks 21 and valleys 22 having an outer diameter smaller than that of the peaks 21 are alternately provided in the axial direction of the connecting pipe 20 . The peak portion 21 has a groove portion 23 that connects the peak portion 21 to two adjacent valley portions 22 .

[0013] A plurality of grooves 23 (six in this embodiment) are provided at intervals from one another in the circumferential direction of the connecting pipe 20 in the ridge portion 21. The plurality of grooves 23 are provided at equal intervals in the circumferential direction in the ridge portion 21.

[0014] 4, the groove 23 has a V-shaped cross section. The bottom surface of the groove 23 is located radially outward of the bottom surfaces of the valleys 22. Examples of the resin material constituting the connecting pipe 20 include polyurethane, polystyrene, polyethylene, polypropylene, ethylene propylene diene rubber, and mixtures thereof. The resin material may contain other additives.

[0015] The connecting tube 20 is preferably made of foam. The connecting pipe 20 in this embodiment is made of closed-cell foamed polyethylene. As shown in FIG. 3, an air layer S is formed between the corner of the valley portion 22 and the covering layer 30.

[0016] Examples of the resin material constituting the coating layer 30 include polyolefins such as polybutene, polyethylene, cross-linked polyethylene, and polypropylene, and vinyl chloride. The above resin materials may be used alone or in combination of two or more. The resin material constituting the coating layer 30 may contain other additives.

[0017] The covering layer 30 in this embodiment is made of polyethylene. A gap is formed between the pipe 11 and the main pipe 20. For example, when the nominal diameter of the pipe 11 is 13A, the size of the gap between the pipe 11 and the main pipe 20 is preferably 1.25 mm to 1.75 mm. In this embodiment, the size of the gap is 1.5 mm.

[0018] Next, the manufacturing apparatus 40 for the composite pipe 10 will be described. 5, the manufacturing apparatus 40 manufactures the composite pipe 10 by moving the pipe body 11 from the left side to the right side of the figure while forming the corrugated pipe 12 around the outer periphery of the pipe body 11. Hereinafter, the moving direction of the pipe body 11 is referred to as moving direction A.

[0019] The manufacturing apparatus 40 includes an extruder 41, a die 41A, a payout machine 46, an extruder 42, a die 42A, a corrugator 44, an extruder 43, a die 43A, a cooling tank 45, and a take-up machine 47, in this order from the upstream side in the moving direction A. The extruder 41 is disposed above the die 41A. The extruder 42 is disposed above the die 42A. The extruder 43 is disposed above the die 43A.

[0020] The unwinding machine 46 unwinds the tube 11 downstream along the moving direction A. The extruder 41 extrudes the adhesion suppressant toward the die 41A. The die 41A applies the adhesion suppressant to the outer peripheral surface of the tube 11 when the tube 11 passes through the die 41A. The adhesion suppressant suppresses adhesion of the base pipe 20 to the outer peripheral surface of the tube 11, and is, for example, silicone oil. The adhesion suppressant may be omitted.

[0021] The extruder 42 extrudes the molten resin material for forming the base pipe 20 toward the die 42A. A foaming agent for promoting the foaming reaction of the resin material is injected or mixed into the resin material. The foaming agent may be a chemical foaming agent or a physical foaming agent. Alternatively, the foaming agent may be a combination of a chemical foaming agent and a physical foaming agent. When the tube 11 passes through the die 42A, the die 42A extrudes the resin material in a cylindrical shape onto the outer periphery of the tube 11. This forms the resin material 20A that covers the outer periphery of the tube 11.

[0022] As shown in Fig. 6, the corrugator 44 has a mold 49 divided into two parts, left and right. Note that in the figure, a molding surface 50 of one of the molds 49 is shown. Although not shown, the corrugator 44 has a plurality of molds 49 arranged side by side along circulation paths provided on both the left and right sides. The corrugator 44 circulates the plurality of molds 49 in synchronization with the movement of the tube 11.

[0023] The molding surface 50 has a semicircular arc shape in cross section. Semicircular ring-shaped recesses 51 for forming the peaks 21 of the base pipe 20 and semicircular ring-shaped protrusions 52 for forming the valleys 22 are alternately provided in the axial direction on the molding surface 50.

[0024] The recess 51 is provided with three protrusions 53 spaced apart from one another in the circumferential direction to form the groove 23. The protrusions 53 are provided on the molding surface 50 of the die 49 in a portion other than the parting surface.

[0025] The recess 51 is provided with a suction groove 54 for sucking air from within the recess 51 by a suction device (not shown). The corrugator 44 brings two dies 49, one on the left and one on the right, close to each other and brings the molding surface 50 into contact with the resin material 20A. The dies 49 mold the resin material 20A while compressing the resin material 20A with the molding surface 50, and move the resin material 20A and the pipe body 11 downstream in the moving direction A by circulating the dies 49.

[0026] 7, the air in the recess 51 of the mold 49 is sucked in by a suction device through the suction groove 54, creating a negative pressure in the recess 51 of the mold 49. As a result, the resin material 20A is deformed radially outward and shaped by the recess 51. Then, a bellows-shaped base pipe 20 is formed in which the peaks 21 and valleys 22 are alternately provided in the axial direction.

[0027] 5 and 8, the extruder 43 extrudes a molten resin material for forming the coating layer 30 toward the die 43A. When the base pipe 20 and the pipe body 11 pass through the die 43A, the die 43A extrudes the resin material in a cylindrical shape onto the outer periphery of the base pipe 20. As a result, the resin material 30A covering the outer periphery of the base pipe 20 is formed.

[0028] At this time, as shown by the arrows in Fig. 8, a suction device (not shown) provided in the die 43A sucks air between the resin material 30A and the base pipe 20. As a result, the resin material 30A deforms radially inward and adheres to the peaks 21 and valleys 22 of the base pipe 20. As a result, a coating layer 30 that coats the outer circumferential surface of the base pipe 20 is formed. In other words, the corrugated pipe 12 is formed.

[0029] 5, the corrugated pipe 12 and the pipe body 11 are cooled when passing through a cooling tank 45. This causes the base pipe 20 and the coating layer 30 that constitute the corrugated pipe 12 to harden. This forms the composite pipe 10.

[0030] The composite pipe 10 is taken up by a take-up machine 47 and wound up by a winding machine (not shown). Next, the operation of this embodiment will be described.

[0031] Since the grooves 23 are provided in the peaks 21 of the base pipe 20, the covering layer 30 is easily mechanically bonded to the base pipe 20 in the circumferential direction of the base pipe 20. In other words, an anchor effect is easily exerted between the base pipe 20 and the covering layer 30 in the circumferential direction of the base pipe 20 (above, action 1).

[0032] When air is sucked in from between the resin material 30A for forming the coating layer 30 extruded into a cylindrical shape from the extruder 43 and the base pipe 20, the air present in the valley portion 22 of the base pipe 20 is easily sucked in through the groove portion 23 of the peak portion 21 (above, effect 2).

[0033] Next, the effects of this embodiment will be described. (1) The peaks 21 have grooves 23 that connect the peaks 21 to two adjacent valleys 22 . According to this configuration, the above-mentioned effect 1 is achieved, and therefore the degree of adhesion between the connecting pipe 20 and the covering layer 30 is improved.

[0034] (2) The plurality of grooves 23 are provided in the ridge portion 21 at intervals in the circumferential direction of the connecting pipe 20 . According to this configuration, since the plurality of grooves 23 are provided in the ridges 21 of the connecting pipe 20 in the above-mentioned manner, the covering layer 30 is more easily mechanically bonded to the connecting pipe 20 in the circumferential direction. Therefore, the degree of adhesion between the connecting pipe 20 and the covering layer 30 is further improved.

[0035] (3) The multiple grooves 23 are provided on the ridges 21 at equal intervals in the circumferential direction. According to this configuration, since the plurality of grooves 23 are provided in the ridges 21 of the connecting pipe 20 in the above-described manner, it is possible to suppress variation in the degree of adhesion between the connecting pipe 20 and the covering layer 30 in the circumferential direction.

[0036] (4) An air layer S is formed between the corners of the valley portions 22 and the covering layer 30. By having such an air layer S, the heat insulating effect of the corrugated pipe 12 can be improved. (5) Since the above-mentioned effect 2 is achieved, the covering layer 30 can be adhered closely to the connecting pipe 20 .

[0037] Furthermore, by changing the number and size of the grooves 23 and the positions of the bottom surfaces of the grooves 23 in the radial direction, it is possible to change how easily the air present in the valleys 22 is sucked in. For example, the further outward the bottom surface of the groove portion 23 is in the radial direction, the more difficult it becomes for air present in the valley portion 22 of the base pipe 20 to be sucked through the groove portion 23 when sucking air from between the resin material 30A and the base pipe 20. For this reason, an air layer S is more likely to be formed between the corners of the valley portion 22 and the covering layer 30. In this way, the degree of adhesion between the base pipe 20 and the covering layer 30 can be easily changed.

[0038] (6) The protrusions 53 that form the grooves 23 are provided on the molding surface 50 of the die 49 at a portion other than the parting surface. According to this configuration, when the pair of left and right dies 49 are separated from each other and released from the connecting pipe 20, interference of the groove portion 23 with the dies 49, that is, so-called forced removal, can be suppressed.

[0039] (7) A gap is formed between the pipe 11 and the connecting pipe 20 . With this configuration, in the manufactured composite pipe 10, the pipe body 11 can be easily inserted into and removed from the corrugated pipe 12.

[0040] <Example of change> The above embodiment can be modified as follows, for example. The present embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0041] By closely adhering the covering layer 30 to the corners of the valley portions 22, it is possible to prevent the air layer S from being formed. The radial position of the bottom surface of the groove portion 23 can be changed as appropriate. For example, the bottom surface of the groove portion 23 can be set at the same radial position as the bottom surface of the valley portion 22, or can be set radially inward from the bottom surface of the valley portion 22.

[0042] The multiple grooves 23 may be provided at uneven intervals in the circumferential direction. There may be one or more grooves 23 in the circumferential direction. The manufacturing method of the composite pipe 10 according to the present invention is not limited to the method exemplified in the above embodiment. For example, a manufacturing method similar to that of the composite pipe 10 described in Patent Document 1, that is, a method in which a resin material for forming the base pipe 20 and a resin material for forming the coating layer 30 are extruded upstream of the corrugator 44, may be used. Even in this case, an effect similar to effect (1) of the above embodiment can be achieved. [Explanation of symbols]

[0043] 10…Composite pipe 11...Body 12...Corrugated pipe 20…Base tube 20A…Resin material 21…Yamabe 22. Valley 23…Groove 30…Covering layer 40...Manufacturing equipment 41...Extruder 41A…Die 42…Extruder 42A…Die 43…Extruder 43A…Die 44…Corrugator 45...Cooling tank 46...Payloader 47...Pick-up machine 49…Mold 50…molding surface 51…Recess 52…Convex part 53…Protrusion 54...Suction groove S: Air layer

Claims

1. A tube body; A corrugated tube covering an outer periphery of the tube body, the corrugated pipe includes a base pipe made of a resin material, and a coating layer made of a resin material and thinner than the base pipe, the coating layer coating an outer circumferential surface of the base pipe, the connecting pipe has a bellows shape in which peaks and valleys having an outer diameter smaller than that of the peaks are alternately provided in an axial direction of the connecting pipe, An air layer is formed between the corners of the valleys and the coating layer. Composite tube.

2. A tube body; A corrugated tube covering an outer periphery of the tube body, the corrugated pipe includes a base pipe made of a resin material, and a coating layer made of a resin material and thinner than the base pipe, the coating layer coating an outer circumferential surface of the base pipe, the connecting pipe has a bellows shape in which peaks and valleys having an outer diameter smaller than that of the peaks are alternately provided in an axial direction of the connecting pipe, An air layer is formed only between the corners of the valley portion and the coating layer among the areas between the valley portion and the coating layer, and there is a portion between the valley portion and the coating layer where no air layer is formed. Composite tube.

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