JPH0718511B2 - Connection structure between composite pipe and pipe joint - Google Patents

Description

The present invention relates to a composite pipe in which at least an inner peripheral surface of a metal pipe is coated with a heat-meltable synthetic resin layer, and a pipe joint to which the composite pipe is connected. Regarding connection structure with.

(Prior Art) Synthetic resin pipes used for water supply pipes, hot water supply pipes, gas pipes, etc. are used in order to increase the connection strength with the pipe joint to be connected
Recently, a method of connecting both by heat fusion has been adopted. Such a structure for connecting a pipe and a pipe joint by heat fusion is disclosed in Japanese Utility Model Publication No. 60-23596 and Japanese Patent Publication No. 55-500479. In the connection structures for pipes and pipe joints disclosed in these publications, the outer peripheral surface of the end portion of the synthetic resin pipe to be connected is arranged on the inner peripheral surface of the pipe joint into which the end portion is fitted. By heating with a heating element, the outer peripheral surface of the end portion of the synthetic resin pipe and the inner peripheral surface of the pipe joint are fused.

(Problems to be solved by the invention) Recently, since the composite pipe in which the inner peripheral surface and the outer peripheral surface of the metal pipe are coated with a synthetic resin layer has excellent corrosion resistance and durability,
Used for hot water supply pipes, etc. In the case of connecting such a composite pipe to a pipe joint, as in the prior art, in the structure in which the pipe outer peripheral surface and the pipe joint inner peripheral surface are connected by heat fusion, the water flowing in the composite pipe is There is a risk that the metal pipe may corrode from the end face to penetrate into the interface between the metal pipe and the synthetic resin layer.

When the synthetic resin layer on the outer peripheral side of the composite pipe and the inner peripheral surface of the joint body are heat-sealed, they are firmly bonded together. On the other hand, the adhesiveness between the synthetic resin layer on the inner circumference side of the composite pipe and the metal pipe is poor, and when tensile force is applied between the pipe joint and the composite pipe, the composite material on the outer periphery side fused to the pipe joint is The resin layer may peel off from the metal pipe together with the pipe joint.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a composite pipe and a pipe joint in which the composite pipe and the pipe joint are firmly adhered to each other and corrosion of the metal pipe in the composite pipe can be surely prevented. To provide the connection structure of. Another object of the present invention is to provide a connecting structure for connecting a composite pipe and a pipe joint which is not likely to be broken even if a tensile force is applied between the connected composite pipe and the pipe joint and has excellent durability. To do.

(Means for Solving the Problem) The present invention provides a connection structure of a composite pipe in which at least an inner peripheral surface of a metal pipe is covered with a heat-meltable synthetic resin layer, and a pipe joint to which the composite pipe is connected. And has an end portion of the composite pipe whose diameter is gradually increased toward the end surface side and an outer peripheral surface that can fit in the end portion of the composite pipe and can be in close contact with the inner peripheral surface of the end portion, And a joint main body made of a heat-meltable synthetic resin for a pipe joint having a heating element disposed therein, wherein the end portion of the composite pipe and the joint main body of the pipe joint are melted by the heat generation of the heating element. It is characterized by wearing, and the above-mentioned object is achieved by it.

Further, the pipe joint has a holding tool for holding the end portion of the composite pipe fitted in the joint body of the pipe joint together with the joint body, thereby achieving the above object.

(Example) Hereinafter, the present invention will be described with reference to Examples.

As shown in FIG. 1, the connecting structure of the composite pipe and the pipe joint according to the present invention comprises a composite pipe 10 and a pipe joint 20 to which an end of the composite pipe 10 is connected.

In the composite pipe 10, for example, an inner peripheral surface and an outer peripheral surface of a metal pipe 11 made of aluminum are coated with heat-meltable synthetic resin layers 12 and 13, respectively. The end portion of the composite pipe 10 connected to the pipe joint 20 is subjected to a diameter expansion process (flare process) so that the diameter gradually increases toward the end face side.

The pipe joint 20 is used, for example, to connect the flanged pipe 30 having the flange portion 31 at the end and the composite pipe 10 described above. The flanged pipe 30 includes an inner peripheral surface of the pipe and a flange portion.
The end surface of 31 is covered with the synthetic resin layer 32.

The pipe joint 20 includes a joint main body 22 having an annular connecting portion 22b capable of being fitted to the expanded end portion of the composite pipe 10, and the connecting portion 22b of the joint main body 22 and the expanded end portion of the composite pipe 10. And a holding tool (23) for holding.

The joint body 22 is made of a heat-meltable synthetic resin and has a connecting portion.
A flange portion 22a is provided at the base end portion of 22b. The flange portion 22a is brought into contact with the flange portion 31 of the flanged pipe 30 via the gasket 21.

A connection 22 that can be fitted into the enlarged end of the composite pipe 10.
The outer peripheral surface of b is tapered so that the diameter becomes smaller toward the tip end side so that the outer peripheral surface of b can come into close contact with the inner peripheral surface of the expanded end portion of the composite pipe 10 to be connected. A heating element 22c made of, for example, a nichrome wire is embedded along the outer peripheral surface of the connecting portion 22b. The heating element 22c is wound along the outer peripheral surface of the connecting portion 22b so as not to overlap each other, and each end of the heating element 22c is led out through the flange portion 22a. The heating element 22c may be provided in a zigzag shape without being wound. When a voltage is applied between the ends of the heating element 22c, the heating element 22c generates heat.

A holding tool 23 for holding the end portion of the composite pipe 10 fitted to the connecting portion 22b of the joint body 22 together with the joint body 22 is fitted with the expanded end portion of the composite pipe 10 to be connected. Obtaining tubular clamp
23b and a flange portion 23 provided at the base end portion of the pressing portion 23b.
have a and. The flange portion 23a is brought into contact with the flange portion 22a of the joint body 22. The clamp 23, the joint body 22, and the respective flange portions 23a, 22a of the flanged pipe 30.
A plurality of bolts 24 are inserted into the bolt 31, and a nut 25 is screwed onto the bolts 24 and tightened, whereby the holding tool 23 and the joint body 22 are integrally attached to the flanged pipe 30.

The pressing portion 23b of the holding tool 23 has a smaller diameter toward the tip so that the inner peripheral surface thereof can be in close contact with the enlarged outer peripheral surface of the end portion of the composite pipe 10 to be connected except for the tip portion thereof. It has a tapered shape. The tip portion of the pressing portion 23b is externally fitted to a tubular portion continuous with the expanded end portion of the composite pipe 10,
Has a constant inner diameter. The outer peripheral surface of the pressing portion 23b is tapered parallel to the outer peripheral surface of the end portion of the composite pipe 10 where the diameter is enlarged.

A predetermined gap is formed between the tapered inner peripheral surface of the pinching portion 23b and the tapered outer peripheral surface of the connecting portion 22b of the joint body 22 facing the inner peripheral surface. The gap is set to be slightly smaller than the wall thickness of the composite pipe 10 when the clamp 23, the joint body 22, and the flanged pipe 30 are integrally tightened by the bolt 24 and the nut 25.

A retaining ring 26 is attached to the tapered inner peripheral portion of the pressing portion 23b. The slip-out preventing ring 26 is provided with an annular protrusion on its inner peripheral surface so as to protrude from the inner peripheral surface of the pressing portion 23b. The number of ridges is not limited to one, and a plurality of ridges may be provided.

The composite pipe 10 and the flanged pipe 30 are connected as follows. First, on the flange portion 31 of the flanged pipe 30, the gasket 21, the flange portion 22a of the joint body 22 of the pipe joint 20, the expanded end portion of the composite pipe 10, and the flange portion of the clamp 23 are provided.
The 32a are sequentially brought into contact with each other, the bolts 24 are inserted through them, and the nuts 25 are screwed and tightened. As a result, the expanded end of the composite pipe 10 is strongly pressed against the connecting portion 22b of the joint body 22 by the pressing portion 23b of the holding tool 23. still,
In order to make the clamp 23 cover the expanded end of the composite pipe 10, the clamp 23 is fitted on the composite pipe 10 before the end of the composite pipe 10 is expanded, and then the pipe end is closed. The part may be expanded. If the end opposite to the enlarged end is not expanded, the opposite end may be fitted. In such a state, the heating element 22c arranged on the outer peripheral surface of the connecting portion 22b is energized to generate heat in the heating element 22c. As a result, the outer peripheral surface of the connection portion 22b of the joint body 22 made of the heat-meltable synthetic resin is heated and melted, and the heat-meltable synthetic resin layer 12 on the inner peripheral surface of the composite pipe 10 contacting the connection portion 22b is also melted. They are heated and melted, and both are fused. Which results in the joint body 22 and composite pipe
10 and are integrally joined.

The end of the composite pipe 10 is expanded, and the end is clamped by the clamp 23 and the joint body 22. Moreover, the end of the composite pipe 10 is connected to the connecting portion 22b of the joint body 22 by the protrusion of the slip-out preventing ring 26 arranged in the pressing portion 23b of the holding tool 23.
Since it is strongly pressed against the pipe joint body 20 and the composite pipe
Even if a tensile force is applied between the composite pipe 10 and
There is no danger of getting out.

If the end portion of the composite pipe 10 is expanded so that the diameter of the end surface becomes large, the inclination angle of the end portion becomes large, and it is strongly clamped by the clamp 23 and the joint body 22, which is preferable. However, since the diameter expansion processing is restricted by the type, elongation, wall thickness, and strength of the welded portion of the metal pipe 11 in the composite pipe 10, when the metal pipe 11 is made of aluminum, the pipe end surface has an inner diameter of 10 mm.
The diameter expansion process is performed so that the diameter becomes larger.

As the axial length of the end portion of the composite pipe 10 to be expanded is longer, the contact area between the composite pipe 10 and the connecting portion 22b of the joint body 22 is larger, and thus the fusion area is larger and the composite area is larger. The joint strength between the pipe 10 and the joint body 22 is improved. However, in the case where the pipe end surface is expanded so as to have a predetermined inner diameter, if the portion to be expanded is lengthened, the inclination angle of the expanded end becomes small, and the composite pipe end The gripping force between the gripping tool (23) and the joint body (22) is weakened.

As the synthetic resin layers 12 and 13 covering the inner peripheral surface and the outer peripheral surface of the metal pipe 11 in the composite pipe 10, an olefin resin such as polyethylene, polypropylene or polybutene, or a mixture or copolymer of these resins is used. . In particular, the cross-linking olefin resin has a large adhesive force with metal,
It is suitable.

The joint body 22 of the pipe joint 20 is made of the same synthetic resin as the synthetic resin layers 12 and 13 of the composite pipe 10.

In the above embodiment, the joint body 22 and the clamp 23 in the pipe joint 20 are tightened with the bolt 24 and the nut 25,
Although the end portion of the composite pipe 10 is clamped by the both, it is not limited to such an embodiment, and for example, the second
As shown in the figure, the joint main body 22 and the clamp 23 are configured to be screwed together, and the clamp 23 is screwed onto the joint main body 22 so that both ends of the composite pipe 10 are connected to each other. It may be configured to be clamped by.

In the above embodiment, the case where the composite pipe 10 is connected to the flanged pipe 30 by the pipe joint 20 has been described.
As shown in FIG. 3, if the joint body 22 has a pair of connecting portions 22b and a pair of clamps 23 and 23 are used,
The composite pipes 10 may be connected to each other.

(Effect of the invention) The connection structure between the composite pipe and the pipe joint of the present invention is as described above.
Since the synthetic resin layer of the composite pipe in which the inner peripheral surface of the metal pipe is covered with the synthetic resin layer is fused to the joint body of the pipe joint, the composite pipe and the joint body are firmly joined and The inner peripheral surface of the joint is reliably sealed. As a result, there is no risk of water infiltrating the interface between the metal tube and the synthetic resin layer in the composite tube, and there is no risk of corrosion of the metal tube.

Further, in the present invention, the end portion of the composite pipe is expanded, and the end portion is clamped by the joint main body and the clamp tool in the pipe joint. Even if tensile force is applied, there is no risk of the composite pipe breaking, and the composite pipe and the pipe joint are firmly joined.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an example of a connecting structure of a composite pipe and a pipe joint of the present invention, and FIGS. 2 and 3 show a composite pipe and a pipe joint of another embodiment of the present invention, respectively. It is a principal part sectional view which shows a connection structure. 10 …… Composite tube, 11 …… Metal tube, 12,13 …… Synthetic resin layer, 20…
… Pipe joint, 22 …… Coupling body, 22b …… Joining part, 23 …… Clamping device, 23 …… Clamping part, 30 …… Flanged pipe.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F16L 47/02

Claims (2)

[Claims] 1. A connection structure of a composite pipe in which at least an inner peripheral surface of a metal pipe is coated with a heat-meltable synthetic resin layer, and a pipe joint to which the composite pipe is connected, wherein The end portion of the composite pipe is gradually expanded in diameter, and the outer peripheral surface is fitted inside the end portion of the composite pipe so as to be in close contact with the inner peripheral surface of the end portion. And a joint body made of a heat-meltable synthetic resin for the pipe joint, wherein the end portion of the composite pipe and the joint body of the pipe joint are fused by heat generation of the heating element. Connection structure between pipe and pipe joint. 2. The composite pipe and the pipe joint according to claim 1, wherein the pipe joint has a holding tool for holding the end portion of the composite pipe fitted in the joint body of the pipe joint together with the joint body. Connection structure.