JP2698007B2 - Manufacturing method of electrofusion joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrofusion joint by injection molding.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 10, a heating wire a is wound in a cylindrical shape to form a cylindrical body b, and the cylindrical body b is set in a mold c and a resin material d is injection-molded. There is known a method of manufacturing an electro-fusion joint e (see, for example,
278919).

In the step of forming the cylindrical body b, the heating wire end f at the other end of the cylindrical body b is folded back to one end, and both heating wire ends f are positioned at one end of the cylindrical body b. By making it in the state of being made, an electric fusion joint e having a current-carrying terminal g on the same end side is manufactured.

[0004]

However, in the case of the above-mentioned conventional manufacturing method, since the heating wire end f at the other end of the cylindrical body b is simply folded back to one end, a resin material is not required during injection molding. Due to the fluid pressure d, there is a disadvantage that the folded portion h is exposed on the surface of the electrofusion joint e.

[0005] As a result, an electrofusion joint e having a poor appearance is caused, and there is a danger that an electric shock will be caused if the exposed portion i is brought into contact during the energization of the fusion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing an electro-fusion joint which can prevent a heating wire from being exposed to an outer surface of the electro-fusion joint. And

[0007]

According to the present invention, there is provided a method for manufacturing an electrofusion joint, comprising: forming a cylindrical body by winding a heating wire into a cylindrical shape; An electric fusion joint in which the end of the heating wire is folded back to one end, and both ends of the heating wire are positioned at one end of the cylindrical body, and the cylindrical body is set in a mold and a resin material is injection-molded. In the manufacturing method, the folded portion of the heating wire to be folded back to one end of the cylindrical body is positioned and fixed to the outer peripheral surface of the cylindrical body.

[0008]

According to the present invention, the folded portion of the heating wire to be folded back to one end of the cylindrical body is positioned and fixed on the outer peripheral surface of the cylindrical body, so that the cylindrical body is set in a mold and the resin material is set. When the injection molding is performed, the injection molding is performed without the flow of the folded portion that is positioned and fixed.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show a process of manufacturing the electrofusion joint 1.

That is, the method of manufacturing the electric fusion joint 1 is a method of arranging the cylindrical body 20 formed by the heating wire 2 in the mold 3 and injection molding the resin material 4.
The heating wire end 21 at the other end of the cylindrical body 20 is folded back to one end of the cylindrical body 20, and the folded portion 22 is positioned and fixed 5 on the outer surface of the cylindrical body 20.

The heating wire 2 is composed of a heating wire main body 23 made of metal.
Is formed of a coated conductor having a coating resin 24 on the outer surface thereof. As shown in FIG. 1, the heating wire 2 is spirally wound around the outer peripheral surface of a cylindrical molding die 6 to form the cylindrical body 2.
It is formed as 0. The cylindrical body 20 is configured so that the coating resin 24 between the adjacent heating wires 2 is ironed 25 to maintain the shape of the cylindrical body 20 without dispersing the whole. Further, in a state where the cylindrical body 20 is formed, the heating wire end 21 located on the other end side is folded back to one end side so that both of the heating wire ends 21 are located on one end side of the cylindrical body 20. Formed. Further, the folded portion 22 is provided with a spot ironing 5
It is positioned and fixed by such as. Thereby, both the heating wire ends 21 are formed in a state where they are located at one end side of the cylindrical body 20 and the whole cylindrical body 20 is substantially unified without being separated.

Next, after the cylindrical body 20 thus formed is provided with an energizing terminal 26 at the end 21 of the cylindrical body 20,
The resin fusion material 1 is manufactured by injecting the resin material 4 in a state where the resin material 4 is taken out from the cylindrical mold 6 and placed in the mold 3. However, as shown in FIG. 3, at this time, it is also possible to arrange the cylindrical mold 6 together with the mold 3 and perform injection molding.

The electric fusion joint 1 thus manufactured
For example, as shown in FIG. 4, the product is butt-connected to a resin tube 10 to be a product as an electro-fused resin tube 11.

According to this manufacturing method, since the cylindrical body 20 is substantially integrated, the folded portion 22 which is particularly susceptible to the flow pressure of the resin material 4 flows and the electrofusion joint 1
Is prevented from being exposed on the outer surface.

In the present embodiment, the folded portion 22 is positioned and fixed to the outer peripheral surface of the cylindrical body 20 by the spot ironing stopper 5, but the positioning and fixing is not limited to such a method. For example, as shown in FIG.
The folded portion 22 may be positioned and fixed to the outer peripheral surface of the cylindrical body 20 by covering the outer peripheral surface of the cylindrical body 20 with the ring 7 formed of an elastic body or the like. However, it is preferable that the ring 7 is made of an insulating material, particularly of the same material as the resin material 4.

As shown in FIG. 6, a ring 8 is provided on the outer peripheral surface of the cylindrical body 20 in advance.
May be configured to be positioned and fixed by inserting the turned-back portion 22 into the insertion hole 81 provided in the second portion. In this case, the insertion hole 81 provided in the ring 8
By adjusting the position of, the outer surface of the cylindrical body 20 and the folded portion 22 can be separated from each other, so that it is possible to prevent the cylindrical body 20 and the folded portion 22 from contacting and short-circuiting when energized. Can also.

Further, in this embodiment, a case is described in which the cylindrical body 20 is formed by a coated conductor having the coating resin 24 on the outer surface of the heating wire main body 23. However, the cylindrical shape shown in FIGS. By using the resin body 9 described above, a cylindrical body 90 consisting only of the heating wire main body 23 can be formed. That is, the resin body 9 has a spiral groove 91 formed on the outer peripheral surface thereof, a positioning portion 92 protruding from a substantially central portion thereof, and a folded portion formed in an insertion hole 93 provided in the positioning portion 92. The heating wire main body 22 can be inserted therethrough. That is, as shown in FIG. 8, the heating wire main body 23 is wound along the groove 91, and the heating wire main body 23, which is the base end of the folded portion 22, is connected to the resin body 9.
After ironing 94 on the outer peripheral surface of the folded portion 22
Is inserted into the insertion hole 93 to form the cylindrical body 90.

Furthermore, in this manufacturing method, the shape of the electrofusion joint 1 to be manufactured is particularly limited as long as the above-described cylindrical body 20 is arranged in the mold 3 and the resin material 4 is injection-molded. Instead, for example, as shown in FIG. 8, it can be manufactured as an electrofusion joint 12 having a cylindrical body 20 at both ends.

[0020]

As described above, according to the present invention, since the injection molding is performed without flowing the folded portion that is positioned and fixed, when the heating wire is exposed on the outer surface of the electrofusion joint, it is almost impossible to perform the injection molding. Can be prevented. As a result, it is possible to prevent the appearance from deteriorating and to prevent electric shock during energization.

[Brief description of the drawings]

FIG. 1 is a process chart showing a manufacturing process of a cylindrical body.

FIG. 2 is a process diagram showing a state in which a cylinder is placed in a mold and injection molding is performed.

FIG. 3 is a process chart showing another embodiment of the injection molding.

FIG. 4 is a front view, a plan view, and a cross-sectional view showing a product state of the electrofusion joint.

FIG. 5 is a sectional view and a front view showing another embodiment of the cylindrical body.

FIG. 6 is a sectional view and a front view showing still another embodiment of the cylindrical body.

FIGS. 7A and 7B are a cross-sectional view and a front view showing a resin body used for manufacturing another cylindrical body. FIGS.

FIG. 8 is a process chart showing still another embodiment of the cylindrical body made of the resin body of FIG. 7;

FIG. 9 is a front view, a plan view, and a sectional view showing another embodiment of the electrofusion joint.

FIG. 10 is a sectional view showing a state of injection molding of a conventional electrofusion joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric fusion joint 2 Heating wire 20 Cylindrical body 21 Heating wire end 22 Folding part 3 Die 4 Resin material 5 Pointing iron (positioning fixation)

Claims (1)

(57) [Claims] An electric heating wire is wound into a cylindrical shape to form a cylindrical body, an end of the heating wire at the other end of the cylindrical body is folded back to one end, and both ends of the heating wire are connected to one end of the cylindrical body. In a method of manufacturing an electric fusion joint in which this cylindrical body is set in a mold and a resin material is injection-molded in a state where is positioned, the folded portion of the heating wire that is to be folded back to one end side of the cylindrical body, A method for manufacturing an electric fusion joint, comprising positioning and fixing the outer peripheral surface of a cylindrical body.