JPH05256392A - Electric fision type plastic pipe joint - Google Patents

Abstract

PURPOSE:To prevent damage due to unnecessary heating, use an inner cylindrical member commonly, and facilitate production by providing the inner cylindrical member made of thermalplastic resin on which an electric heater wire is wound on the inner peripheral surface of a pipe fitting zone at the end of a pipe joint, and connecting the electric heater wire at the outside of the pipe joint. CONSTITUTION:A connecting member 10 is made by injection-molding an outer cylindrical member 13 on the outer surface of an inner cylindrical member 12 on which one line of electric heater wire 11 is wound, and resin pipes 21 and 22 are installed in the inner surface of it. The inner cylindrical member 12 is made of a thermoplastic resin such as polyethylene, etc., and its outer surface is provided with spiral grooves 14 for receiving the electric heater wire 11. The connecting member 10 and an intermediate member 20 are heated by another heating panel, etc., and, when each end of them becomes fused, the both ends are pressed each other quickly to thermal-fuse together. The connecting members 10 and 10 on each end is provided with two connector pins 15 and 16. Each one of the connector pins 16 and 16 is connected together by a covered lead 3 on the outer surface of the pipe joint. As a result, the connecting member 10 and inner cylindrical member 12 can be used commonly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion type plastic pipe joint in which a heating wire is embedded on the inner surface side of the pipe joint for connecting a thermoplastic resin pipe.

[0002]

2. Description of the Related Art Conventionally, there is an electric fusion type plastic pipe joint shown in FIG. 4 disclosed in Japanese Patent Laid-Open No. 57-69015. This product has a groove on the outer surface from one end to the other end, and an electric charge is applied to the groove of the inner member provided so that the wall thickness between the bottom portion and the inner surface of the groove is gradually increased toward the center side in the axial direction. This is an electrofusion-type plastic pipe joint in which a heating wire is provided and the inner member and the heating wire are surrounded by an outer member.

[0003]

In the above prior art, an inner member having substantially the same axial length as the outer member forming the pipe joint body is provided, and the inner member has a larger size in the central portion in the axial direction. It has a wall thickness with the inner surface and prevents damage to the pipe joint caused by heating of the heating wire without completely fitting the resin pipe into the pipe joint. However, since the heating wire has an increased wall thickness between the bottom of the groove and the inner surface of the internal member at the center of the pipe fitting, the effect of heating the heating wire on the inner surface of the fitting is due to the wall thickness at the center. However, the effect of heating when the resin pipe is completely installed inside the pipe joint is also small at the end side of the installed resin pipe, and fusion bonding with the resin pipe even in the completely installed state Occurs in the mounting area of the resin pipe, which is not uniform.

Further, the heating wire is buried from one end to the other end of the pipe joint, and melting is performed inside the pipe joint even in the central portion where the resin pipe is not mounted, which is not preferable for the pipe joint. Furthermore, the inner member requires a thin inner member having a shape corresponding to the joint shape of each socket, elbow, cheese, etc.
In addition, a heating wire must be provided in the groove of this internal member,
Due to the molding of the inner member, it is difficult for the molten resin to spread in the mold,
Further, the larger the size of the process of winding the heating wire around the inner member, the more difficult it is, and there are many manufacturing problems. The present invention solves the above problems and melts and joins the resin pipe mounted by heating the inner surface of the pipe joint with a heating wire only in the resin pipe mounting region where the resin pipe is mounted in the pipe joint body, and also the resin pipe. The area inside the pipe joint body where no is attached is not heated at all, thus ensuring the fusion bonding between the pipe joint and the resin pipe, and eliminating the adverse effect on the pipe joint body due to heating and facilitating the manufacture of the pipe joint. The present invention provides an electric fusion type plastic pipe joint.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a pipe joint in which a thermoplastic resin pipe is mounted on the inner surface of an end portion and melt-bonded,
On the inner peripheral side of the pipe mounting area that receives the resin pipe to the inner surface of the end of the pipe joint, a tubular inner cylindrical member made of a thermoplastic resin around which a heating wire of one system is wound is provided corresponding to the mounting area. The electric fusion-bonding plastic pipe joint is characterized in that the heating wire of each inner cylinder member provided in the pipe mounting area is connected outside the pipe joint. In the above, it is characterized in that a cover made of a thermoplastic resin is covered on the connecting portion connected to the outside of the pipe joint to seal the surface of the pipe joint.

[0006]

Since the present invention has the above-mentioned structure, the inner tubular member is arranged only in the mounting area of the resin pipe to the pipe joint, and therefore the heating wire is buried only in the mounting area of the pipe, and the mounting area of the pipe is No heating wire is embedded in the members except. Therefore, the heating by the heating wire is effectively utilized only for the fusion connection with the resin pipe, and the heating of the heating wire prevents an adverse effect on the pipe joint body. Further, also in the production of the joint, it is possible to commonly use the inner cylinder member corresponding to the diameter of the resin pipe to be connected regardless of the shape of the joint. Therefore, even in the production of a joint having a different shape or a joint having a different caliber, heat fusion is performed using a member having no embedded heating wire, or the outer cylinder member is integrally molded on the outer surface of the inner cylinder member. Pipe fittings can be easily manufactured. Further, also in the connection work with the resin pipe, since the connection work can be performed by simultaneously energizing the heating wire in which the pipe joint is buried, the connection work can be performed easily in a short time. Also, since the connecting portion is sealed by the cover on the surface of the pipe joint, there is no risk of causing electrical problems due to contact with soil or water during connection with the pipe, and good connection work can be performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an electric fusion type plastic pipe joint 1 showing an embodiment of the present invention. In the figure, reference numeral 20 denotes a tubular intermediate member provided with a thermoplastic resin that forms the central portion of the pipe joint of the present embodiment, and although it has an elbow shape in the figure, it may be a socket type according to the shape of various pipe joints. The same is true for the teeth type. The intermediate member 20 forms a portion excluding the mounting area of the resin pipes 21 and 22, and may be formed by injection molding in advance. Further, as will be described later, after the inner cylinder members 12 and 12 are manufactured, the inner cylinder members are manufactured. It may be formed integrally with 12 by injection molding.

The connecting member 10 is formed by injection-molding an outer cylinder member 13 in a mold on the outer surface of an inner cylinder member 12 around which a heating wire 11 of one system is wound, and a resin pipe 2 connected to this inner surface.
1, 22 are mounted. The inner cylindrical member 12 is a thin-walled cylindrical shape made of a thermoplastic resin such as polyethylene, the inner surface has an inner diameter for receiving the thermoplastic resin tube to be connected, and the outer surface has a spiral groove 14 for receiving the heating wire 11. A heating wire 11 made of stainless steel, copper, or the like for resistance heating is wound around the groove 14, and both ends of the heating wire 11 are connected to connector pins 15 and 16 installed on outer surfaces of both ends of the inner tubular member 12.

A heating wire 11 of one system is embedded in the connecting member 10 provided in the mounting area where the resin pipes 21 and 22 are mounted in the pipe joint 1, and the central portion where the resin pipes 21 and 22 are not mounted is the above-mentioned portion. It is provided by the intermediate member 20. For example, both end faces facing each other are heated by separate heating plates, etc., and when each end face reaches a molten state, the heating plates are removed and both end faces are quickly pressed. As a result, the connecting member 10 is integrally heat-sealed to the end portion side of the intermediate member 20.
Two connector pins 15 and 16 respectively project from the connecting members 10 and 10 on each end side, and one connector pin 16 and 16 of these connector pins 16 and 16 are provided on the outer surface of the pipe joint by the covered conductor 3. It is connected. The outer surface of the coated wire 3 is covered with a cover made of a thermoplastic resin, and the periphery of the cover is heat-sealed to the surface of the pipe joint to be integrally joined, and the connection wire portion is completely shielded from the external environment. I am doing it. Since the connecting member 10 is provided only in the mounting area of the resin pipes 21 and 22, it is only necessary to prepare one that corresponds to the diameter of the resin pipes 21 and 22 to be connected. Therefore, it is necessary to prepare one having the shape of the entire pipe joint 1. Therefore, the connecting member 10 and the inner cylinder member 12 can be made common in the same pipe diameter size.

The intermediate member 20 and the connecting member 10 may be integrated by heat fusion as described above, and as another embodiment, as shown in FIG. 2, a tooth-shaped groove 71 is provided on the inner surface of the intermediate member 70. The sleeve 45 of the connecting member 40 is fitted into the tooth-shaped groove 71 through the packing 73, and a metallic stay funner 41 such as a copper pipe is attached to the fitted inner surface side to form the stay funner.
The diameter of 41 may be increased, and the intermediate member 70 and the connecting member 40 may be integrated in a sealed state. Further, instead of the tooth-shaped groove 71, screws that are screwed with each other may be provided, and the intermediate member 70 and the connection member 40 may be screwed together in a sealed state to be integrated. After being integrated, the connector pins 16, 1 of the both-end connecting members 40, 40
6 is connected by the covered conductor 3. Also in this case, as described above, the cover is joined to the surface of the pipe joint at the connection portion by the covered conductor 3 to seal the connection connection portion and to shield it from the external environment.

Further, FIG. 3 is a sectional view for explaining another embodiment. The mold 60 of the injection molding machine is composed of two halves each having a cavity 61, and mandrels 62 and 63 are mounted in the cavity 61. Mandrels 62, 6
3 is an inner cylinder member 12, 12 around which the heating wire 11 is wound.
Is attached to each mandrel 62, 63. The connector pins 15 and 16 are fixed by a mold 60 so as not to move. In this state, a molten thermoplastic resin such as polyethylene is injected from the runner 64 from the injection cylinder of the injection molding machine, and the inner surface of the cavity 61 and the outer surfaces of the inner cylinder members 12 and 12 around which the heating wire is wound. The outer cylinder member 17 is molded between the above and. Due to the injected molten resin of the outer cylinder member 17, the outer surfaces of the inner cylinder members 12 and 12 are separated from each other.
Is integrally heat-bonded to each connector-pin 15, 1
6 projects from the outer surface of the outer cylinder member 17 and is integrated. After molding in this way, the connector pins 16 and 1
6 is connected to the outside of the pipe joint to form an electro-fusion type plastic pipe joint 1.

In connection with the resin pipe, as shown in FIG. 1, a resin pipe 21, which is connected to the inner surfaces of both ends of the pipe joint 1,
After inserting 22, the electric power from the controller 30 is applied to the connector pins 15 and 16 protruding to the outer surfaces of both ends of the pipe joint 1. Electric power from the controller is supplied from one heating wire 11 to the other heating wire 11 via the coated conductor 3. Since the heating wire 11 is embedded only in the portion of the pipe joint where the resin pipes 21 and 21 are mounted, the outer peripheral surface of the mounted resin pipes 21 and 22 is heated to efficiently control the controller.
Power from 30 is consumed. The connector pins 15 and 16 are connected in parallel to each other on the outer surface of the pipe joint,
Electric power from the controller may be applied to each heating wire 11.

[0013]

As described above, in the electric fusion-bonding type plastic pipe joint of the present invention, the heating wire is not buried in the portion excluding the mounting region of the resin pipe to be connected, and therefore the heating is not performed.
The heating energy by the heating wire is efficiently and effectively utilized only for fusion connection with the resin pipe. Further, since the excess portion in the pipe joint is not heated, damage due to unnecessary heating in the pipe joint is prevented. Also, since it is possible to standardize the inner cylinder members with the same pipe diameter size, it is not necessary to provide an inner cylinder member for each joint shape as in the conventional case, and the manufacture of joints of various shapes and different diameters can be made accordingly. It can be done simply by providing. Further, since the connecting portion is cut off from the outside, no electrical problem occurs and good connection can be performed.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric fusion type plastic pipe joint showing an embodiment of the present invention.

FIG. 2 is a sectional view of a plastic pipe joint of another embodiment.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a plastic pipe joint according to another embodiment.

FIG. 4 is a partial sectional view of a plastic pipe joint showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrofusion type plastic pipe joint 3 Coated conducting wire 10, 40, 50 Connection member 11 Heating wire 12 Inner cylinder member 13, 17 Outer cylinder member 14 Groove 15, 16 Connector pin 20, 70 Intermediate member 30 Controller 41 Three-wheel Boo 45 Stay funner 60 Mold 61 Cavity 62, 63 Mandrel 64 Runner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Kato 2 Daifuku, Kuwana City, Mie Prefecture Hitachi Metals Co., Ltd. Kuwana Factory

Claims (2)

[Claims] 1. A pipe joint in which a thermoplastic resin pipe is mounted on an inner surface of an end portion and melt-bonded to each other, and the inner peripheral side of a pipe mounting area for receiving the resin pipe to the inner surface of the end portion of the pipe joint corresponds to the mounting area. Then, a cylindrical inner cylinder member made of a thermoplastic resin around which one line of heating wire is wound is provided, and the heating wire of each inner cylinder member provided in the pipe mounting area is connected outside the pipe joint. An electric fusion type plastic pipe joint characterized by. 2. The electrofusion-type plastic pipe joint according to claim 1, wherein a cover made of a thermoplastic resin is covered on a connecting portion connected to the outside of the pipe joint to seal the surface of the pipe joint. ..