JPH0868487A - Composite pipe connecting structure and pipe end treatment method - Google Patents

Abstract

PURPOSE: To provide an end part treatment method that can improve the durability of a composite pipe and prevent the infiltration of a fluid into the fiber layer of the composite pipe. CONSTITUTION: A composite pipe having an outer surface resin layer 6, an inner surface resin layer 3 and a reinforced fiber layer 5 in between is used. Groove machining is applied to the end face of the composite pipe, and the outer surface resin layer 6 and the inner surface resin layer 3 are softend by heating and bent to cover the end face of the reinforced fiber layer 5 so as to prevent the reinforced fiber layer 5 from getting wet. The composite pipe is then jointed to another member 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure for connecting a composite pipe having a fiber reinforced layer to a valve, a socket, a strainer and other members. The present invention also relates to a method for treating a pipe end portion of a composite pipe having a fiber reinforced layer.

[0002]

2. Description of the Related Art Conventionally, steel pipes have been commonly used as pipes for transporting high-pressure fluid. However, since steel pipes are very heavy, they are difficult to construct, and may corrode depending on the properties of the fluid to be transported, so in recent years, composite pipes are often used instead of steel pipes. Here, the composite pipe is a pipe mainly composed of a resin, and a fiber layer for reinforcement is arranged around the resin pipe (Japanese Patent Laid-Open No. 2-11988, et al.). In many cases, a resin layer is provided on the outermost layer of the composite pipe.

By the way, in the case of performing piping construction using a composite pipe, it is necessary to connect other members such as a valve and a socket to the composite pipe. However, the connection structure peculiar to the composite pipe is not generally popularized, and the composite pipe is currently connected to other members by the same means as a normal pipe. The connection structure of the composite pipe of the prior art is as shown in FIG.
The connection procedure is generally as follows. That is, when connecting the composite pipe 100, the composite pipe 100 is first cut into a predetermined size at a site or a factory. Then, if necessary, the end portion is tapered about 1/30 to 1/45 (not shown in FIG. 14).

Further, the opening of the socket 101 and the like is preliminarily taper-processed (not shown in FIG. 14).
When the resin material of the composite pipe 100 is, for example, a vinyl chloride resin, an appropriate adhesive is applied to the outer periphery 102 of the end of the composite pipe 100, and the end is inserted into the opening of another member for adhesive connection. . When the resin material of the composite pipe 100 is a polyolefin resin such as polyethylene resin, heat fusion is performed instead of the above-mentioned adhesive. In addition to these measures, a pipe screw may be provided on the outer surface of the composite pipe 100 and the composite pipe 100 may be connected by a mechanical fitting means.

However, in the connection structure of the composite pipe 100 of the prior art, the pipe end surface 103 of the composite pipe 100 is not processed at all, no matter which of the above-mentioned measures is adopted. That is, in the prior art, the tube end of the composite tube 100 is in a so-called “cut and cut” state, and the reinforcing fiber layer 105 is exposed from the tube end surface 103.

[0006]

The composite pipe connection structure of the prior art has a simple structure and is easy to install, but has a problem of poor durability. That is, in the connection structure of the composite pipe of the conventional technique, the fiber layer 105 was exposed from the pipe end surface 103 of the composite pipe 100, so the fluid flowing through the composite pipe 100 directly wets the exposed surface of the fiber layer 105. Then, the fluid enters the fiber layer 105. Therefore, during long-term use of the pipe, delamination may occur between the fiber layer 105 and the resin layers inside and outside the fiber layer 105, and the composite pipe 100 may be damaged.

The present invention focuses on the above-mentioned problems of the prior art, and an object thereof is to provide a connecting structure for a composite pipe having excellent durability. In addition, the present invention also provides a fiber layer 10 of a composite pipe.
It is an object of the present invention to provide a method for treating an end portion of a composite pipe, which is capable of preventing fluid from entering the inside of the container 5.

[0008]

The present invention for achieving the above object provides a composite pipe having a thermoplastic resin layer on an outer surface and an inner surface and a fiber layer in an intermediate portion and another member having an opening. In the connecting structure of the composite pipe to be connected, the end surface of the composite pipe is grooved, and at least one of the thermoplastic resin layers on the outer surface and the inner surface of the composite pipe closes the groove formed by the groove processing. Is bent so that the thermoplastic resin layer wraps the fiber layer in the middle portion of the composite pipe, and at least one of the thermoplastic resin layers on the outer surface and the inner surface of the composite pipe is the inner surface of the opening provided in the other member. Alternatively, it is a connection structure for a composite pipe, which is in close contact with at least one of the outer surfaces.

A desirable method for pipe end treatment of a composite pipe for achieving the above-mentioned connection structure is a pipe end treatment method for a composite pipe having a thermoplastic resin layer on an outer surface and an inner surface and a fiber layer in an intermediate portion. A groove is formed on the end surface of the composite pipe, and at least one of the thermoplastic resin layers on the outer surface and the inner surface is heated and softened, and the thermoplastic resin layer is bent to include the end surface of the fiber layer and the thermoplastic resin layer. Is welded to the other thermoplastic resin layer, which is a pipe end treatment method for a composite pipe.

Another aspect of the present invention for attaining the above object is to connect a composite pipe having a resin layer on an outer surface and an inner surface and a fiber layer at an intermediate portion to another member having an opening. In the structure, the resin layer on the outer surface and the fiber layer on the middle portion are removed at the tip of the composite pipe, while the other members have steps inside the opening, and the large diameter portion near the opening end and the small diameter portion inside The outer surface of the tip end of the composite pipe is adhered or fused to the inner surface of the small diameter part of the other member, and the outer surface near the tip end of the composite pipe is adhered or fused to the inner surface of the large diameter part of the other member. It is a connecting structure of a composite pipe characterized in that.

[0011]

According to the first aspect of the invention, the end surface of the composite pipe is grooved, and at least one of the thermoplastic resin layers inside and outside the composite pipe is bent so as to close the groove. As a result, the fiber layer in the central portion of the composite pipe is wrapped by the bent thermoplastic resin layer, and the fiber layer is not exposed to the outside. Since the thermoplastic resin layer on the outer surface or the inner surface of the composite tube in this state is in close contact with at least one of the inner surface and the outer surface of the opening provided in the other member, The layer does not come into contact with the fluid flowing through the tube.

In the pipe end treatment method of the composite pipe according to the second aspect, first, the end face of the composite pipe is grooved. Here, since the fiber layer exists in the middle portion of the composite pipe, the end face of the fiber layer is slightly inside from the end face of the composite pipe due to the groove processing. Then, at least one of the thermoplastic resin layers on the inner and outer surfaces is heated and softened. Further, the thermoplastic resin layer is bent and welded to the other thermoplastic resin layer. However, since part or all of the fiber layer at the tip portion is removed by the groove processing performed earlier, the heat of the inner and outer layers is reduced. The plastic resin layers are in direct contact with each other. Further, as described above, since the end surface of the fiber layer is slightly inside from the end surface of the composite pipe, the end surface of the fiber layer is included by the bent thermoplastic resin layer. Therefore, the fiber layer is not exposed from the end surface of the composite pipe.

According to the composite pipe connecting structure of the third aspect, the resin layer on the outer surface and the fiber layer on the intermediate portion are removed at the tip of the composite pipe. Therefore, the exposed surface of the fiber layer appears between the removed portion and the non-removed portion. Then, in the composite pipe connection structure of the present invention, the other member is provided with a step in the opening and is divided into a large diameter portion and a small diameter portion, and the outer surface of the distal end portion of the composite pipe is bonded to the inner surface of the small diameter portion of another member or The outer surface in the vicinity of the tip of the composite pipe is fused and adhered or fused to the inner surface of the large diameter portion of the other member. Therefore, the portion where the exposed surface of the fiber layer communicates with the inside of the composite tube is completely sealed by the connection between the outer surface of the tip of the composite tube and the inner surface of the small diameter portion of the other member. Further, the portion where the exposed surface of the fiber layer communicates with the outside of the composite pipe is blocked by the connection between the outer surface near the tip of the composite pipe and the inner surface of the large diameter portion of the other member. Therefore, the exposed surface of the fiber layer is completely disconnected from the inside and outside of the composite pipe, and the fluid flowing through the composite pipe and the rainwater outside do not come into contact with the fiber layer.

[0014]

EXAMPLES Specific examples of the present invention will be described below. FIG. 1 is a cross-sectional view of a composite pipe to which the composite pipe connection structure of the present invention is applied. FIG. 2 is a cross-sectional view of the composite pipe when grooving the end surface of the composite pipe. 3 and 4 are cross-sectional views of the composite pipe when the end portion of the composite pipe is heated. Figure 5
It is sectional drawing of a composite pipe at the time of welding the thermoplastic resin layers of an inner surface and an outer surface. FIG. 6 is a cross-sectional view showing a connecting structure of a composite pipe in a specific embodiment of the present invention. FIG. 7 is a cross-sectional view of a composite pipe showing a modified example of grooving the end face of the composite pipe.
FIG. 8 is a cross-sectional view of a composite pipe showing a modified embodiment when welding the thermoplastic resin layers on the inner and outer surfaces. 9 and 1
0 is a cross-sectional view showing a connecting structure of a composite pipe in a specific embodiment of the present invention.

A composite pipe 1 to which the present invention can be applied is, for example, as shown in FIG. 1, and is made of a polyvinyl chloride resin, a polyethylene resin, a polyphenylene sulfide (PPS) resin, a polyvinylidene fluoride resin (PVDF) or the like. It has an inner resin layer 3 of a plastic resin. A reinforcing fiber layer 5 is arranged outside the inner surface resin layer 3. There is no limitation on the material constituting the reinforcing fiber layer 5, and typical examples thereof include glass fiber and carbon fiber.

The fiber may be in the form of a mat, a cloth, whiskers, or long fibers arranged side by side. The orientation of the fibers is known to be such that the fibers surround the inner surface layer 3 in a spiral shape, or are arranged in the longitudinal direction. In the composite pipe 1, the outer surface resin layer 6 is provided on the outer periphery of the reinforcing fiber layer 5. The material of the outer surface resin layer 6 is the same thermoplastic resin as the inner surface resin layer 3 described above. In the present embodiment, in order to facilitate the description, a three-layer structure including the inner surface resin layer 3, the reinforcing fiber layer 5 and the outer surface resin layer 6 will be described as an example. Further, it may be more complicated, for example, a plurality of reinforcing fiber layers 5 may be provided, or another resin layer or a foam layer may exist between the reinforcing fiber layers 5.

The connection structure of the composite pipe and the pipe end treatment method of this embodiment will be described below in accordance with the piping construction procedure. First, when connecting the composite pipe 1, the composite pipe 1 is cut into a required length. Therefore, the end surface of the composite pipe 1 at this time is perpendicular to the outer peripheral surface as shown in FIG.
Next, the end surface of the composite pipe 1 is grooved. The shape of the groove 7 provided on the end face is preferably V-shaped. By forming the groove 7, the reinforcing fiber layer 5 on the end face is formed as shown in FIG.
Are removed, and the inner surface resin layer 3 and the outer surface resin layer 6 having sharp edges appear at the ends of the composite pipe 1. Then, the end portion of the reinforced resin layer 5 exists at a position slightly recessed from the end surface of the composite pipe 1. Further, a V-shaped groove is also formed in the reinforced resin layer 5 itself.

Here, a method of forming the groove 7 on the end surface of the composite pipe 1 will be described. It is desirable that the groove processing is performed by a cutting means such as a cutting tool. More specifically, it is recommended to employ the groove carving device 10 as shown in FIG. The structure of the groove carving device 10 includes a slide portion 11, a rotary shaft 12 and cutting teeth 13. Slide part 11
Has a tubular shape slightly smaller than the inner diameter of the composite pipe 1, and the ball 15 is rotatably mounted on the outer peripheral surface thereof. In addition, in the hole 17 provided at the center of the slide portion 11, the rotary shaft 12
Has been inserted. Since the rotary shaft 12 is inserted into the slide portion 11 via the ball bearing 18, the rotary shaft 12 is
It is rotatable with respect to the slide portion 11, but moves integrally in the axial direction.

The cutting teeth 13 are of milling type,
A large number of cutting blades 20 having a triangular cross section are provided on one surface of a disk-shaped base 22 by drawing a circle. The diameter of the circle formed by the cutting blade 20 is equal to the average of the inner diameter and the outer diameter of the composite pipe 1 to be processed. The cutting teeth 13 are integrally attached to the rotary shaft 12.

When the groove 7 is provided on the end surface of the composite pipe 1 by using the groove engraving device 10, the slide portion 1 of the groove engraving device 10 is used.
1 is inserted into the pipe of the composite pipe 1 and the cutting blade 20 is inserted into the composite pipe 1
The cutting tooth 13 is rotated while contacting the end surface of the cutting tooth 13. Then, the reinforcing fiber layer 5 exposed on the end face of the composite pipe 1 is scraped off, and the groove 7 having a V-shaped cross section is formed on the end face of the composite pipe 1. Since balls are provided on the outer peripheral surface of the slide portion 11, the slide portion moves in the axial direction in the composite pipe 1 along with cutting, and the cutting teeth 13 are fed.

The method of providing the groove 7 on the end surface of the composite tube 1 may be achieved by pressing the disk-shaped heater 23, which will be described later, very strongly against the end surface and then heating the end surface of the composite tube 1 in addition to the above-mentioned method. It is possible.

When the grooving of the end surface of the composite pipe 1 is completed by a method such as cutting, the grooved end surface is heated next.
The heating of the end face is performed by pressing a disk-shaped heater 23 as shown in FIG. 3 against the end face of the composite pipe 1. The disc-shaped heater 23 is formed by providing a disc-shaped heat-generating base 25 with an annular projection 26 that matches the groove 7. An electric heater (not shown) is built in the heat generating base 25. Materials for the heat generating base 25 and the annular projection 26 are preferably excellent in heat conduction, and aluminum or copper alloy is recommended, but of course, stainless steel or steel may be used. It is desirable that the heat generating substrate 25 and the annular projection 26 be coated with a resin having excellent releasability such as polytetrafume ethylene so that the resin of the composite tube 1 does not adhere thereto.

The heating of the end face is performed by the inner resin layer 3 and the outer resin layer 6
To the extent that heat fusion is possible. The degree of heating is performed by appropriately adjusting the temperature of the disk heater 23 and the time for pressing the disk heater 23 against the composite tube 1. A specific value such as the temperature of the disk-shaped heater 23 should be arbitrarily selected depending on the material of the resin forming the inner surface resin layer 3 and the like, the outside air temperature and the like. When the inner resin layer 3 is made of vinyl chloride resin, the disk-shaped heater 2
The temperature of 3 is maintained at about 260 ° C, and the disk-shaped heater 23
When was pressed against the composite tube 1 for about 15 seconds, good results could be obtained.

After the inner surface resin layer 3 and the outer surface resin layer 6 are sufficiently heated, both the inner surface resin layer 3 and the outer surface resin layer 6 are bent so that they are brought into contact with each other and fused. It is desirable to use a dedicated jig 27 as shown in FIG. 5 for bending work and fusing work of the inner surface resin layer 3 and the outer surface resin layer 6. The jig 27 is
It is a disk-shaped member, and a groove 28 having a V-shaped cross section is provided in an annular shape on one surface. It is desirable that the jig 27 is also coated with a resin having excellent releasability, such as polytetrafluoroethylene, so that the resin of the composite pipe 1 does not adhere to it. When the jig 27 is used, the groove 28 of the jig 27 is aligned with the end surface of the composite pipe 1, and the end surface is pressed slowly.

Then, the end portions of the composite pipe 1, that is, the end portions of the inner surface resin layer 3 and the outer surface resin layer 6 which have an acute angle contact the groove 28 of the jig 27, and the inner surface resin layer 3 and the outer surface resin layer 6 are separated from each other. The tips are guided by the V-shape on the side surface of the groove 28, and the tips gradually approach each other. That is, the V groove 7 on the end surface of the composite pipe 1 is gradually closed, and finally the inner surface resin layer 3 and the outer surface resin layer 6 are matched and fused. Further, since the end surface of the reinforcing fiber layer 5 exists at a position slightly recessed from the end surface of the composite pipe 1, when the inner resin layer 3 and the outer resin layer 6 are fused, the end surface of the reinforcing fiber layer 5 is completely removed. It is wrapped in the inside resin layer 3 and the outside resin layer 6.

An adhesive is applied to the outer peripheral surface of the composite pipe 1 whose end has been treated as described above, the composite pipe 1 is inserted into the opening 31 of the other member 2 such as a valve, and the composite pipe 1 is bonded through the adhesive. The outer peripheral surface and the inner peripheral surface of the other member 2 are brought into close contact with each other. In the structure of the composite pipe 1 and the other member 2 connected in this way, the end portion of the composite pipe 1 is grooved as shown in FIG. 6, and the inner surface resin layer 3 and the outer surface of the composite pipe 1 are formed. The resin layers 6 are bent together so that the groove 7 is closed. Therefore, the end portion of the reinforcing fiber layer 5 is wrapped by the inner resin layer 3 and the outer resin layer 6. The outer peripheral surface of the composite pipe 1 in this state is adhered to the inner surface of the other member 2. The member numbered 29 in FIG. 6 is a resin annular member, and is inserted between the composite pipe 1 and the other member 2 for the purpose of reducing the change in the flow path and reducing the pressure loss. ..

Therefore, the composite pipe 1 is substantially solid and the other member 2
It is connected to the. In addition, all the end faces of the reinforcing fiber layer 5 are covered with the inner surface resin layer 3 and the outer surface resin layer 6, and no portion is exposed to the outside.

In the above embodiments, the groove formed on the end face of the composite pipe 1 has a V-shaped cross section, but of course it may have another cross section. However, in view of the ease of bending the inner resin layer 3 and the outer resin layer 6 and the beauty of the finished shape, it is desirable that the cross-sectional shape of the groove be gradually deeper toward the center. In addition to the V-shape described above, the cross-sectional shape satisfying such conditions includes an arc-shaped groove 9 as shown in FIG. Further, in the above-mentioned embodiment, the structure in which both the inner surface resin layer 3 and the outer surface resin layer 6 are bent and the inner surface resin layer 3 and the outer surface resin layer 6 are made to coincide with each other is shown in FIG. By using such a jig in which one wall surface has a linear groove, only one resin layer can be bent and welded to the other.

The connecting means between the composite pipe 1 and the other member 2 is
In this embodiment, the adhesive is used as an example, but other known methods as described in the prior art can be applied. For example, when the outer surface resin layer 6 of the composite pipe 1 is a polyolefin resin as shown in FIG. 9, it is desirable to connect them by heat fusion. At that time, the heating wire 65 is embedded inside the other member 2. The inner surface of the other member 2 may be melted by the heat generated by the heating wire 65 to connect the composite pipe 1 and the other member 2.

Of course, as shown in FIG. 10, the outer peripheral surface of the composite pipe 1 is threaded, and the composite pipe 1 and the other member 2 are threaded through the screw.
It is also possible to connect.

In the previous embodiment, the jig 27 was described as being made of a simple metal member, but it is desirable to add a heat retaining function to the jig 27 by incorporating a heating wire into the jig 27. In some cases. That is, depending on the type of resin forming the composite pipe 1, internal stress may remain due to rapid cooling. Therefore, when this type of resin is used, the jig 27 is placed at about 40 ° C to 80 ° C. It is desirable to keep it at.

Next, another invention for achieving the same object as the above-mentioned invention will be described with reference to FIGS. 11 to 13. FIG. 11 is a perspective view of the tip of the composite pipe. FIG. 12 is an exploded cross-sectional view showing a connecting structure for a composite pipe in a specific example of the present invention. FIG. 13 is a cross-sectional view showing a connecting structure of a composite pipe in a specific example of the present invention.

In the connection structure of this embodiment, the tip end of the composite pipe 70 is peeled off, and the other member 71 having steps 72 and 73 is used. That is, in the connection structure of the present embodiment, the outer surface resin layer 6 and the reinforcing fiber layer 5 are removed from the distal end portion of the composite pipe 70, and the inner surface resin layer 3 is exposed as shown in FIG. A step 74 is provided between the tip of the composite pipe 70 and the portion not subjected to the peeling process. Therefore, the reinforcing fiber layer 5 is exposed at the step 74.

On the other hand, the other member 71 is provided with two steps 72 and 73 in the opening as shown in FIG. 12, and the inside of the opening is divided into three inner diameter portions. That is, the large-diameter portion 75 having the largest inner diameter is formed at the portion closest to the opening end. The inner diameter of the large diameter portion 75 is equal to the outer diameter of the composite pipe 70.
A portion 76 continuing from the large diameter portion 75 via the step 72 has an inner diameter smaller than that of the large diameter portion 75. The portion functions as the small diameter portion 76. The outer shape of the small-diameter portion 76 is the composite pipe 7 described above.
It is equal to the outer diameter of the tip portion of 0, that is, the outer diameter of the exposed inner surface resin layer 3. The inner portion of the small diameter portion 76 further inside has a smaller inner diameter than the small diameter portion 76, and the portion functions as a flow path 78 through which the fluid passes. The inner diameter of the flow path 78 is equal to the inner diameter of the composite pipe 70.

In the composite pipe connecting structure of the present embodiment, the tip end of the composite pipe 70 and a portion adjacent to the tip end are inserted into the opening of the other member 71. The tip of the composite pipe 70 is in contact with the small diameter portion 76 of the other member 71, and the outer diameter of the composite pipe 70 is in contact with the large diameter portion 75 of the other member 71. An adhesive 80 is interposed between the tip of the composite pipe 70 and the small diameter portion 76 of the other member 71, and the two are in close contact with each other by the adhesive 80. Similarly, the outer diameter portion of the composite pipe 70 and the other member 7
The adhesive 81 is also applied between the large diameter portions 75 of No. 1 so that the two are firmly brought into close contact with each other.

Therefore, in the connecting structure of the composite pipe of this embodiment,
The composite pipe 70 is connected to the other member 71, and a continuous flow path is formed between them. In the connection structure according to the present embodiment, the tip of the composite pipe 70 and the small diameter portion 76 of the other member 71 are in close contact with each other, and the outer diameter portion of the composite pipe 70 and the large diameter of the other member 71 are important. The portions corresponding to the stepped portion 72 of the other member 71 are
It is completely isolated from both the flow path and the outside. Here, in the present embodiment, the reinforcing fiber layer 5 of the composite pipe 70 is the other member 71.
It is exposed at a portion corresponding to the stepped portion 72. Therefore, the exposed portion of the reinforcing fiber layer 5 is completely isolated from both the flow path and the outside and does not communicate with the outside. Therefore, the reinforcing fiber layer 5 does not come into contact with the fluid flowing through the flow path and does not come into contact with external rainwater or the like. Further, according to the connection structure of the present embodiment, a sufficient bonding area can be secured both at the tip of the composite pipe 70 and at the outer diameter part of the composite pipe 70, so that the reinforcing fiber layer 5 can be completely isolated. is there.

In this embodiment, as a means for bringing the distal end portion of the composite pipe 70 and the small diameter portion 76 of the other member 71 into close contact with each other, a method using an adhesive has been described. Of course, as described in the previous invention. A heat fusion means is also effective.

[0038]

According to the connection structure of the composite pipe of claim 1,
The fiber layer in the central portion of the composite pipe is wrapped by the thermoplastic resin layer, and the fiber layer is not exposed to the outside. Therefore, according to the connecting structure of the composite pipe of the present invention, the fiber layer does not come into contact with the fluid flowing through the pipe, and the delamination is less likely to occur, and the durability is excellent.

In the pipe end treatment method for a composite pipe according to the present invention, since the end face of the fiber layer is included by the bent thermoplastic resin layer, the fiber layer is not exposed from the end face of the composite pipe. . Therefore, the fiber layer does not communicate with the flow path or the outside when connected to other members by using a known method in combination. Therefore, the composite pipe which has been subjected to the method for treating the end of the composite pipe according to claim 2 has an effect of having a long life.

In the composite pipe connecting structure according to the third aspect, the front and rear portions of the exposed surface of the fiber layer are in close contact with the large diameter portion and the small diameter portion of the other member, respectively. Therefore, in the structure of the present invention, the exposed portion of the fiber layer is completely disconnected from the inside and outside, and the fluid flowing through the composite pipe and the rainwater outside does not come into contact with the fiber layer. Therefore, in the composite pipe connecting structure according to the third aspect, there is an effect that delamination of the composite pipe with time does not easily occur, and the durability is excellent.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a composite pipe to which a composite pipe connection structure of the present invention is applied.

FIG. 2 is a cross-sectional view of the composite pipe when grooving the end surface of the composite pipe.

FIG. 3 is a cross-sectional view of the composite pipe when the end portion of the composite pipe is heated.

FIG. 4 is a cross-sectional view of the composite pipe when the end portion of the composite pipe is heated.

FIG. 5 is a cross-sectional view of the composite pipe when the thermoplastic resin layers on the inner and outer surfaces are welded to each other.

FIG. 6 is a cross-sectional view showing a connecting structure of a composite pipe in a specific example of the present invention.

FIG. 7 is a cross-sectional view of a composite pipe showing a modified example of grooving the end face of the composite pipe.

FIG. 8 is a cross-sectional view of a composite pipe showing a modified example when the thermoplastic resin layers on the inner and outer surfaces are welded to each other.

FIG. 9 is a cross-sectional view showing a connecting structure of a composite pipe in a specific example of the present invention.

FIG. 10 is a cross-sectional view showing a connection structure for a composite pipe in a specific example of the present invention.

FIG. 11 is a perspective view of a distal end portion of a composite pipe.

FIG. 12 is an exploded cross-sectional view showing a connecting structure for a composite pipe in a specific example of the present invention.

FIG. 13 is a cross-sectional view showing a connecting structure for a composite pipe in a specific example of the present invention.

FIG. 14 is a cross-sectional view showing a prior art composite pipe connection structure.

[Explanation of symbols]

 1,70 Composite pipe 2,71 Other member 3 Inner surface resin layer 5 Reinforcing fiber layer 6 Outer surface resin layer 7,9 Groove 10 Groove engraving device 23 Disc heater 25 Heat generating base 26 Annular protrusion 27 Jig 75 Large diameter portion 76 Small diameter portion

Claims (3)

[Claims] 1. In a connecting structure of a composite pipe for connecting a composite pipe having a thermoplastic resin layer on an outer surface and an inner surface and having a fiber layer in an intermediate portion to another member having an opening, an end portion of the composite pipe is provided at an end surface. Groove processing is performed, and at least one of the thermoplastic resin layers on the outer surface and the inner surface of the composite pipe is bent so as to close the groove formed by the groove processing, and the thermoplastic resin layer forms an intermediate portion of the composite pipe. Of the composite pipe, wherein at least one of the thermoplastic resin layers on the outer surface and the inner surface of the composite pipe is in close contact with at least one of the inner surface and the outer surface of the opening provided in the other member. Pipe connection structure. 2. A pipe end treatment method for a composite pipe having a thermoplastic resin layer on the outer surface and the inner surface and a fiber layer in the middle part, wherein a groove is formed on the end surface of the composite pipe to form a thermoplastic resin on the outer surface and the inner surface. At least one of the resin layers is softened by heating, the thermoplastic resin layer is bent to include the end face of the fiber layer, and the thermoplastic resin layer is welded to the other thermoplastic resin layer. Pipe end treatment method. 3. A composite pipe connecting structure for connecting a composite pipe having a resin layer on an outer surface and an inner surface and having a fiber layer in an intermediate portion to another member having an opening, wherein a resin on the outer surface is provided at a front end portion of the composite pipe. The layer and the fiber layer in the middle part are removed, while the other member has a step inside the opening and is divided into a large diameter part near the opening end and a small inside diameter part, and the outer surface of the tip of the composite pipe is another member. A connecting structure for a composite pipe, wherein the inner surface of the small-diameter portion is adhered or fused, and the outer surface near the tip of the composite pipe is adhered or fused to the inner surface of the large-diameter portion of another member.