JPH07145897A - Electrodeposition coupling - Google Patents

Abstract

PURPOSE:To provide an electrodeposition coupling which enables uniform deposition on a periphery in a state that the axes of a coupling body and a pipe are accurately held and an uniform gap is provided between the inner surface of a socket and an outer surface of a pipe. CONSTITUTION:A thin protrusion piece 8 brought into contact with the outer periphery of a pipe and holding a pipe in an annular shape is formed on the pipe socket 4 of an electric fusion coupling made of thermoplastic resin having a heat generating substance disposed on the inner surface of the pipe socket 4 of a coupling body 1. A taper inner surface 5 brought into contact with the outer surface of the end part of an inserted pipe and concentrically holding the pipe end part with the coupling body 1 is formed on the deep part of the pipe socket 4. A gap between the inner surface of the socket and the outer surface of the pipe is held in a uniform state and molten resin is prevented from being escaped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion joint for connecting thermoplastic synthetic resin pipes such as polybutene and polyethylene. More specifically, the mutual positional relationship between the joint body and the pipe is correct during the electric fusion connection work. The present invention relates to an electric fusion joint capable of performing fusion work while maintaining the state.

[0002]

2. Description of the Related Art Conventionally, there is the one shown in FIG. 2 disclosed in, for example, Japanese Patent Laid-Open No. 19494/1992. In this one, a plurality of fastening portions 24 are provided at the receiving end portion of the joint body, and the outer surface of the pipe 14 inserted into the receiving port is fastened to prevent the pipe from slipping out and moving. This is omitted.

[0003] As another prior art, the actual Kaihei 3-126
There is one shown in FIG. 3 disclosed in Japanese Patent Publication No. 96. In this product, a plurality of centering ribs 15 having a diameter smaller than the outer diameter of the pipe are provided on the end side of the inner surface of the joint main body to prevent the pipe P2 from coming out and center the pipe, and to omit the clamp jig. It is the one.

[0004]

In all of the above-mentioned prior arts, a clamp jig used for fusion splicing is omitted, and a projecting piece or a centering rib is provided on the end side of the receiving port. This prevents the pipe from slipping out, but when there is a gap between the inner surface of the receiving port and the outer surface of the pipe, that is, when the outer diameter of the pipe is small or the pipe is distorted in an elliptical shape, Alternatively, the pipe may tilt in the pipe receiving opening of the main body with the centering rib as a base point, and the distance between the receiving opening inner surface and the pipe outer peripheral surface may not be uniform.

When the pipes are thus connected in a state where the pipes are inclined in the receiving port of the joint body, uniform fusion splicing is not performed,
On the circumference of the pipe, an excessively large melted portion and an insufficient melted portion occur. There is also a problem in that the axis of the connection is wrong and the appearance is not good. The conventional technique shown in FIG. 3 has a problem that the mandrel cannot be removed during molding. The present invention solves the above problems and provides an electric fusion joint capable of accurately holding the axial center of the joint body and the pipe and evenly welding them circumferentially with a uniform gap between the inner surface of the receiving port and the outer surface of the pipe. It is provided.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is, in an electrofusion joint made of thermoplastic synthetic resin, in which a heating element is disposed on the inner surface of the pipe receiving port of the joint body, the outer circumference of the pipe inserted into the pipe receiving port. A thin-walled projection that abuts against the pipe to hold the pipe in an annular shape is formed at the end of the pipe receiving port, and contacts the outer surface of the end of the pipe inserted in the pipe receiving port to fix the pipe end to the joint body. It is an electric fusion splicing joint characterized in that a tapered inner surface for holding it concentrically is formed in the inner depth of the pipe receiving opening.

[0007]

Since the present invention has the above-mentioned structure, when the thermoplastic synthetic resin pipe connected to the inner surface of the receiving port of the joint body is inserted,
The outer surface of the end portion of the tube abuts the inner surface of the taper formed in the inner portion of the receiving port and simultaneously receives a diameter reducing action. Therefore, the flatness in the case where the pipe end is aligned with the axial center of the receiving port and the pipe is flat is corrected to a perfect circle and held. On the other hand, at the receiving end of the joint body, there is also formed a thin-walled annular projecting piece that comes into contact with the outer surface of the pipe and holds the pipe body concentrically with respect to the joint body. It is held concentrically with the joint body.

Therefore, since the pipe is held concentrically at both the inner depth and the end of the joint body receiving port, the inner face of the receiving port and the outer face of the pipe are circumferentially and longitudinally (axially) relative to the inner face of the receiving port. The gap is uniformly maintained, and the entire circumference of the inserted tube is fusion-bonded uniformly by the heat generated by the heating element arranged on the inner surface of the receiving port.

Further, since the circumference of the pipe is held in an annular shape by the inner back portion of the receiving port and the end portion on the inlet side, the resin melted in the joint body due to the heat generation of the heating element causes the inner rear portion of the receiving port or the inlet side of the end portion to be melted. There is no sticking out, and the molten resin acts as a heat quantity for fusing the outer surface of the pipe without waste, so that the fusing of the pipe can be reliably performed and fusion splicing can be performed. Further, the clamp jig for holding the tube, which has been used in the past, becomes unnecessary.

[0010]

FIG. 1 is a sectional view of an electric fusion joint showing an embodiment of the present invention. In the figure, 1 is a joint body made of a thermoplastic resin made of the same material as the resin pipe 7 to be connected, and a heating wire 2 which is a heating element is embedded in the inner surface. The heating wire 2 is connected to connector pins 3 protruding from the outer surfaces of both ends of the joint body 1. Reference numeral 4 denotes a receiving port for a pipe that receives the connecting resin pipe, and the inner back portion of the receiving port 4 is formed as a tapered inner surface 5. When the resin pipe 7 to be connected is inserted into the tapered inner surface 5, the outer surface of the end portion of the pipe 7 abuts, and the inner diameter of the small diameter side on the inner side is smaller than the specified minimum dimension of the pipe 7. There is. An annular stopper 6 for restricting the insertion depth of the pipe is formed at the center of the joint body at the inner side of the inner surface of the taper.

A thin annular projecting piece 8 is provided at the inlet end of the receiving port 4. The inner diameter of the projecting piece 8 is slightly smaller than the outer diameter of the pipe 7, and the inlet side of the end is A trumpet-shaped guide portion 9 is provided so that the tube 7 can be easily inserted. Since the projecting piece 8 is thin, the inner diameter of the projecting piece 8 is expanded when the tube 7 is inserted. Further, the inner diameter of the projecting piece 8 is expanded even during molding, so that the mandrel for molding the inside of the joint body 1 can be easily pulled out.

The electrofusion joint of this embodiment is as described above, and when the pipe 7 is inserted into the receiving port 4 of the joint body 1 at the time of fusion splicing, the end of the pipe 7 abuts on the inner surface of the taper to some extent. It is held on the axial center of the receiving port while being subjected to the diameter reducing action, and at the same time, it is also held on the axial center of the receiving port by the projecting piece 8 on the inlet side. Therefore, it is held on the inner surface of the receiving port of the joint body in the circumferential and longitudinal directions at the axial center, and even when the pipe 7 is flat, it is held in a state corrected by the tapered inner surface and the projecting piece. Therefore, the inner surface of the receiving port 4 and the outer surface of the tube 7 inserted into the receiving port are held in a uniform gap as a whole.

When the current from the controller is applied to the connector pin 3 after inserting the tube 7 in this way, the heating wire 2 embedded in the inner surface of the receiving port 4 generates heat and the resin of the joint body around the heating wire is melted. The molten resin expands to the outer surface side (inner diameter side) of the tube 7 to fill the gap with the outer surface of the tube 7, and melts the outer surface of the tube 7 with the expanded molten resin pressure. At this time, since the molten resin is in contact with the inner rear portion of the receiving port 4 and the outer peripheral surface of the inlet-side end common pipe 7, the molten resin is prevented from protruding to the rear side or the inlet side of the receiving port. For this reason, the expansion pressure of the molten resin effectively acts on the melting of the outer surface of the pipe, and it is combined with the uniform gap of the receiving port to perform reliable and accurate fusion splicing.

[0014]

As described above, the electric fusion splicing joint of the present invention enables reliable and accurate fusion splicing. Moreover, the conventional clamp jig for holding the pipe is not required.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electric fusion joint showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a conventional technique.

FIG. 3 is a partial cross-sectional view showing another conventional technique.

[Explanation of symbols]

 1 Joint body 2 Connector pin 3 Heating wire 4 Pipe receiving port 5 Taper inner surface 6 Stopper 7 Connection resin pipe 8 Projection piece 9 Guide part

Claims (1)

[Claims] 1. An electrofusion joint made of a thermoplastic synthetic resin in which a heating element is arranged on the inner surface of a pipe receiving opening of a joint body, and the pipe is held in an annular shape by abutting on the outer circumference of the pipe inserted in the pipe receiving opening. A thin projecting piece is formed at the end of the pipe receiving opening, and a tapered inner surface that abuts the outer surface of the end of the pipe inserted in the pipe receiving opening and holds the pipe end concentrically with respect to the joint body An electric fusion splicing joint, characterized in that it is formed in the inner part of the receiving port.