JP2000213684A - Electrodeposited coupling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeposited coupling capable of providing a one- side receiving resin pipe preventing water leakage from a socket for a long period of time. SOLUTION: It is an electrodeposited coupling 2 to be fused on one end of a polyethylene pipe 1 and used to form a socket 22 incorporating a heating resistant wire 23, constituted of a thin cylindrical bobbin body 25 on an outer peripheral surface of which spiral grooves 251 are continuously provided, the heating resistant wire 23 spirally wound around and arranged in the inside of the groove 251 of this bobbin body 25 and a coupling main body 20 injection- molded and formed around the bobbin body 25 on the side where this heating resistant wire 23 is positioned, and one end of the bobbin body 25 is extended to one end of the coupling main body 20, and a ring projection 27 formed on an outer peripheral surface of this extended part 26 is fused and integrally formed on an inner peripheral surface of the coupling main body 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric welding joint used by being welded to one end of a thermoplastic resin pipe such as a polyethylene pipe, which is a piping material used in the field of clean water and sewage.

[0002]

2. Description of the Related Art Conventionally, as a means for connecting polyethylene pipes, an electric welding joint having a built-in and arranged heating resistance wire such as a nichrome wire on the inner surface side of a receiving port has been used. As the electric welding joint, there is known an electric welding joint using a coated wire in which the periphery of the heating resistance wire is insulated and coated with the same resin material as the joint, or using a bare heating resistance wire as it is. For example, an electric welding joint using a covered wire is illustrated in Japanese Patent Application Laid-Open No. 5-50531, while an electric welding joint using a bare heating wire is illustrated in Japanese Patent Publication No. 1-454510.

As shown in FIG. 4, instead of connecting adjacent polyethylene pipes using the electric welding joint, one end 11 of one polyethylene pipe 1 is fused to one end 21 of the small diameter side of the electric welding joint 2 as shown in FIG. By connecting, a single-sided polyethylene pipe P is manufactured.
The end portion 31 of the other polyethylene pipe 3 is inserted into the receiving port 22, and a means for connecting the polyethylene pipes by applying a current to the heating resistance wire 23 existing on the inner surface side of the receiving port 22 is adopted. In addition, 24, 24 are connection terminals for energization, and are electrically connected to both ends of the heating resistance wire 23.

[0004]

However, single-sided polyethylene pipes manufactured using the above-mentioned electric welding joints have the following problems. In the case of an electro-welded joint using the above-mentioned covered wire as a heating resistance wire, when heating the wire, the covering resin layer covering the wire is melted and integrated with the joint body, so that the polyethylene pipes Although there is no problem such as water leakage at the fusion splicing portion, there is a problem in that the cost of the coated wire is high, so that the electric welding joint is expensive.

On the other hand, in the case of an electric welding joint using a bare heating wire, as shown in FIG. 5, the interface between the cylindrical bobbin body 25 and the joint main body 20 has poor adhesion. When a predetermined internal water pressure is always applied to the inside of the pipe, such as a pipe, a gap S is formed between the bobbin body 25 and the joint body 20. There was a problem that leakage occurred.

In this case, as shown in FIG. 6, one end of the bobbin body 25 is extended to one end 21 on the small diameter side of the joint body 20, and the end face of the extended portion 26 is connected to one end 21 of the joint body 20.
It is possible to prevent short-term water leakage from occurring by melt-connecting the polyethylene pipe with one end face together with the face.

However, the extending portion 26 of the bobbin body 25
Is simply flat, the outer peripheral surface of the extending portion 26 of the bobbin body 25 is not substantially melted and integrated with the inner peripheral surface of the joint body 20. For this reason, when the internal water pressure is constantly applied in the pipeline for a long period of time, as shown in FIG. 6, a crack C is generated in the inclined portion of the extending portion 26, and the crack C is used to cause the bobbin 25 A gap S is generated between the connection terminal 24 and the joint body 20, and water leaks from the portion of the connection terminal 24 for energization through the gap S as in the case of FIG. 5 described above.

[0008] An object of the present invention is to provide an electric welded joint capable of obtaining a one-sided receiving tube which does not cause water leakage from the receiving port for a long time.

[0009]

According to the present invention, there is provided an electric welding joint which is used by being welded to one end of a thermoplastic resin pipe to form a receiving port having a built-in heating resistance wire, A thin cylindrical bobbin body having a spiral groove continuously provided on the outer peripheral surface, a heating resistance wire spirally wound in the groove of the bobbin body, and the heating resistance wire are located. And one end of the bobbin body is extended to one end of the joint body to be welded to one end of a thermoplastic resin pipe, and the extension is provided. The uneven portion formed on the outer peripheral surface of the portion is fused and integrated with the inner peripheral surface of the joint body.

In the present invention, the material of the joint body and the bobbin body constituting the electric welding joint may be a thermoplastic resin such as polyethylene, polypropylene, and vinyl chloride resin. Preferably, the joint body is made of high-density polyethylene, and the bobbin body is made of medium-density polyethylene. The joint body may have a bridge structure.

(Function) In the electric welding joint according to the first aspect of the present invention, one end of the thin cylindrical bobbin extends to one end of the joint main body, and irregularities formed on the outer peripheral surface of the extending portion. Since the portion is melt-integrated with the inner peripheral surface of the joint main body, a water path such as a crack which causes water leakage does not occur in the interface region between the bobbin body and the joint main body due to a load such as water pressure. For this reason, it is possible to obtain a thermoplastic resin tube having a receiving port that does not leak water for a long time.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part showing a first embodiment of the electric welding joint of the present invention, FIG. 2 is a cross-sectional view of a main part showing a modification of FIG. 1, and FIG. 3 shows a manufacturing process of the electric welding joint of FIG. FIG.

In FIG. 1, the electric welding joint 2 has basically the same structure as that shown in FIG. 6, and is formed by injection molding around the bobbin body 25, the heating resistance wire 23, and the bobbin body 25. And the joint body 20. The bobbin body 25 is a thin-walled cylindrical member injection-molded from medium-density polyethylene, and a spiral groove 251 is continuously provided on the outer peripheral surface of the large diameter portion. A heating resistance wire 23 not covered with insulation is spirally wound and arranged in the groove 251, and both ends of the heating resistance wire 23 are connected to a connection terminal 2 for conducting electricity.
4, 24 are electrically connected. The joint body 20 is made of high-density polyethylene.

One end of the bobbin 25 extends to one end 21 of the joint body 20 on the small diameter side. The extending portion 26 includes a large-diameter portion 261, an inclined portion 262, and a small-diameter portion 263.
A large number of annular projections 27 are integrally provided on the outer peripheral surfaces of the inclined portion 262 and the small diameter portion 263 at predetermined intervals.
The cross-sectional shape of the annular projection 27 may be a rectangular shape or a mountain-shaped cross-sectional shape as shown in FIG.

Then, around the bobbin body 25 in which the heating resistance wire 23 is spirally wound in the groove 251, molten polyethylene to be the joint body 20 is injection-molded, and the inner peripheral surface of the joint body 20 is formed. Is fused and integrated with the outer peripheral surfaces of a large number of annular projections 27 of the bobbin body 25 to form the electric welding joint 2 of the present invention.

As described above, in the electric welding joint 2 shown in FIGS. 1 and 2, the rectangular or chevron-shaped cross-section projecting from both outer peripheral surfaces of the inclined portion 262 and the small-diameter portion 263 as the extending portion 26 of the bobbin body 25 is provided. Since a large number of annular projections 27 are likely to be in a molten state by the heat of the resin of the molten polyethylene to be injection-molded, the melt adhesion between the bobbin body 25 and the joint body 20 is extremely good. For this reason, as shown by the broken line in FIG. 1 or FIG. 2, even if the one end surface 21 on the small diameter side of the electric welding joint 2 is melt-connected to the one end surface of the polyethylene pipe 1, long-term water leakage is prevented. be able to.

Next, a method of manufacturing the electric welding joint 2 of the above embodiment will be described with reference to FIG. First, FIG.
As shown in (a), the movable outer dies 51, 51 and the fixed outer dies 5
The cavity of the mold 5 composed of the inner mold 4 and the inner mold 52 is filled with a medium-density polyethylene melted from a gate by an injection molding machine (not shown), cooled and solidified.
Is opened vertically to obtain a thin-walled cylindrical bobbin body 25 having a continuous spiral groove 251 around the inner mold 52. Note that the movable outer mold 51 is divided in the vertical direction in the figure.

Next, as shown in FIG. 3 (b), using a winding machine (not shown), the heating resistance wire 23 is inserted into the groove 251 of the cylindrical bobbin body 25 with the inner die 52 attached. , And connecting terminals 24, 2
4 are electrically connected.

Then, as shown in FIG.
The second movable outer molds 53, 53 are arranged so that a predetermined space is formed around the inner mold 52 with the bobbin body 25 on which the heating resistance wire 23 is arranged and mounted in 1, and the bobbin is formed. A cavity formed by the outer peripheral surface of the body 25 and the inner peripheral surface of the second movable outer mold 53 is filled with a high-density polyethylene melted from a gate portion by an injection molding machine (not shown) to form a joint body. Form the layer. Then, after cooling and solidification, the upper and lower movable outer mold 53 and inner mold 52 are removed from the mold, thereby obtaining the electrofusion joint 2 as shown in FIG. In this case,
The fixed outer mold 54 is the same as that in the case of FIG.
I also use it.

[0020]

According to the first aspect of the present invention, one end of the bobbin is extended to one end of the joint body to be welded to one end of the thermoplastic resin pipe, and the outer periphery of the extended portion is provided. Since the uneven portion formed on the surface is melt-integrated with the inner peripheral surface of the joint main body, a gap serving as a source of water leakage does not occur in an interface region between the bobbin body and the joint main body due to a load such as water pressure. As a result, it is possible to obtain a thermoplastic resin tube having a receiving port that does not leak water for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a first embodiment of an electric welding joint of the present invention.

FIG. 2 is a sectional view of a main part showing a modification of FIG. 1;

FIG. 3 is a schematic explanatory view showing a manufacturing process of the electric welding joint of FIG. 1;

FIG. 4 is a schematic explanatory view showing a polyethylene pipe to which a conventional electric welding joint is welded.

FIG. 5 is an enlarged sectional view of a main part showing a use state of the polyethylene pipe of FIG. 4;

FIG. 6 is an enlarged sectional view of a main part showing a use state of another conventional electric welding joint.

[Explanation of symbols]

 P Single-sided polyethylene pipe 1, 3 Polyethylene pipe 2 Electro-welding joint 20 Joint body 21 One end on the small diameter side 22 Receptacle 23 Heating resistance wire 24 Connection terminal for energization 25 Bobbin body 251 Spiral groove 26 Extended part 261 Large diameter part 262 Inclined part 263 Small diameter part 27 Annular projection (irregular part) 5 Mold 51, 53 Moving outer mold 52 Inner mold 54 Fixed outer mold

Claims (1)

[Claims] 1. An electric welding joint which is used by being welded to one end of a thermoplastic resin pipe to form a receiving port having a built-in heating resistance wire, wherein a spiral groove is continuously provided on an outer peripheral surface. A thin cylindrical bobbin body, a heating resistance wire spirally wound in a groove of the bobbin body, and an injection molding formed around the bobbin body on which the heating resistance wire is located. One end of the bobbin body is extended to one end of the joint body to be welded to one end of the thermoplastic resin pipe, and the uneven portion formed on the outer peripheral surface of the extended portion is An electrically welded joint characterized by being melt-integrated with the inner peripheral surface of the joint.