JPH0740376A - Manufacture of electric welding joint - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for easily manufacturing an electric fusion joint in which a heating wire is embedded at a constant interval and a depth on an inner peripheral surface of a receiving port. [Structure] The ring body 3 made of synthetic resin, in which the columns 32 are provided upright on the outer peripheral surface, is externally fitted to both ends of the core 2. Next, heating wire 4
One end of the ring body 3 is entangled with the support 32 of the ring body 3, the heating wire 4 is wound around the outer peripheral surface of the core 2 between the ring body 3 and the other ring body 3, and the other end is Engage with the column 32 of the ring body 3. Then, the terminal pins 5 are attached to the columns 32 of the respective ring bodies 3, the outer peripheral side of the core 2 is covered with a dividable outer mold 1 and the mold is closed, and then the inside of the cavity formed by the outer mold 1 and the core 2. The molten resin is injected into. [Effect] The mold can be easily closed, and the electric fusion joint in which the heating wire is embedded in the inner peripheral surface of the receiving opening at a constant interval and depth can be easily manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electric fusion joint in which a heating wire is embedded in a spiral shape on the inner peripheral surface of a synthetic resin joint body.

[0002]

2. Description of the Related Art Conventionally, for connecting gas pipes, water supply pipes, hot water supply pipes and the like, there has been used an electric fusion joint in which a heating wire is embedded in an inner peripheral surface of a receiving opening of a joint body. As an example of a method for manufacturing this electric fusion joint, for example, Japanese Patent Publication No. 3-75795,
Preforms with struts standing on the outer peripheral surfaces of both ends are externally fixed to the core, then one end of the heating wire is entangled with one of the struts, and then the heating wire is wound around the outer peripheral surface of the preform. A manufacturing method has been proposed in which the end portion is entangled with the other strut, the outer peripheral surface of the core is covered with a separable outer mold, the mold is closed, and molten resin is injected into the cavity formed by the outer mold and the core. ing.

[0003]

However, in the case of this manufacturing method, the heating wire which is not covered with the insulating resin is heated and wound around the outer peripheral surface of the preform, and then a predetermined tension is applied to the preform. Since the heating wire is embedded in the outer peripheral surface of the molded product, the intervals of the heating wire spirally wound may become uneven. Also, since the embedded depth of the heating wire is not constant depending on the heating temperature, tension, etc. of the heating wire, the gap between the heating wires is not constant, and when the heating wire is heated, the inner peripheral surface of the receptacle is May not melt uniformly.

The present invention has solved the above problems and provides a method for easily manufacturing an electric fusion joint in which heating wires are embedded in the inner peripheral surface of a receiving opening at regular intervals and depths. .

[0005]

According to the present invention, first, a synthetic resin ring body in which columns are erected on the outer peripheral surface is externally fitted to both ends of a core forming the inner peripheral surface of the joint body. Then, one end of the heating wire covered with an insulating resin is entangled with the support of one ring body, and the heating wire is wound around the outer peripheral surface of the core between the ring body and the other ring body, The other end of the heating wire is entangled with the support of the other ring body. Thereafter, terminal pins are attached to the columns of each ring body, the outer peripheral side of the core is covered with a dividable outer mold, and the mold is closed, and then molten resin is injected into the cavity formed by the outer mold and the core. It is characterized by

[0006]

Since the synthetic resin ring body is externally inserted into the core and the terminal pins are attached to the columns of the ring body, the outer die can be easily closed. Further, since the heating wire covered with the insulating resin is wound around the outer peripheral surface of the core, the interval and the depth of the adjacent heating wires are constant.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a mold device used in the present invention, and FIG. 2 is a cross-sectional view of an electric fusion joint manufactured by the present invention, in which 1 is a dividable member. The mold 2 is a pair of left and right cores. Reference numeral 3 is a ring body made of synthetic resin such as polyethylene or polybutene, and 4 is a heating wire.

The manufacturing method of the present invention comprises the steps of winding the heating wire 4 around the outer peripheral surface of the core 2, closing the outer peripheral side of the core 2 with the mold 1, and closing the mold 1 and the core 2. And the step of injecting a molten resin into the cavity formed by the above. In the present invention, the heating wire 4 whose outer surface such as a nichrome wire is covered with an insulating resin such as polyethylene or polybutene is used. The thickness of the insulating resin can be appropriately set according to the wire diameter of the nichrome wire or the like, but is usually 0.2 mm to
It may be set appropriately within the range of 3.0 mm.

In the step of winding the heating wire 4, first, the ring body 3 made of synthetic resin is prepared, and the ring body 3 is externally attached to each core 2. A support rod 62 made of a conductive metal is erected on the outer peripheral surface of the synthetic resin ring body 3. The ring body 3 is externally inserted into the core 2 and a positioning recess 31 is provided on the side edge thereof. The protrusion 21 provided on the core 2 is fitted and fixed so as not to rotate. Next, the tips of the cores 2 are butted and held concentrically, and the columns 32 that are erected on the outer peripheral surface of the ring body 3 are fixed so that they are located on the same axis. Therefore, the pair of left and right cores 2 is set on a rotation shaft (not shown).

Next, one end of the heating wire 4 wound on a bobbin or the like is pulled out, the insulating resin at the end is peeled off, and then entangled with the support column 32 of one ring body 3 and fixed by welding or the like. To do. Therefore, while rotating the pair of left and right cores 2 about the axis, the outer peripheral surface of the core 2 extends from the side edge of one ring body 3 in which one end of the heating wire 4 is entangled to the side edge of the other ring body 3. Wind the heating wire 4. At this time, the heating wire 4 is wound in a coil shape while applying a constant tension to the heating wire 4 so that the adjacent heating wires are in close contact with each other. Then, while measuring the winding length of the heating wire 4 with a counter or the like, the winding wire is wound around the core 2 for a predetermined length, and then the heating wire 4 is cut, and the insulating resin at the tip portion thereof is peeled off, and the other ring body 3 is cut. It is entwined with the support column 32 and fixed by welding or the like.

When the heating wire 4 is wound, an electric heating iron or the like is pressed against the outer peripheral surface of the heating wire 4 wound in a coil shape to melt the insulating resin covering the outer surface of the heating wire 4. If the adjacent heating wires 4 are partially fused, the heating wires 4
It is possible to reliably prevent the positional deviation of the.

After the heating wire 4 is wound around the outer peripheral surface of the core 2 in this manner, the terminal pins 5 are fitted and fixed to the columns 32 of the respective ring bodies 3, and the terminal holding member 11 is attached to the terminal pins 5. Mounting. Therefore, the outer peripheral side of the core 2 is covered with the mold 1, and the mold 1 is fitted and inserted while aligning the fitting hole 12 provided in the mold 1 and the terminal holding member 11 mounted on the terminal pin 5. Close the mold. At this time, since the terminal pin 5 and the terminal holding member 11 are fixed to the column 32, the mold closing of the mold 1 can be performed very easily.

Finally, a molten resin such as polyethylene or polybutene is injected into the cavity formed by the outer mold 1 and the core 2. Then, when the mold 1 is opened after waiting for the hardening of the molten resin and the core 2 and the terminal holding member 11 are pulled out from the joint body, an electric fusion joint as shown in FIG. 2 is obtained. That is, the receiving ports 61 are provided at both ends of the joint body 6, and the heating wire 4 is embedded in a spiral shape on the inner peripheral surface of each of the receiving ports 61, and both ends of the heating wire 4 are connected to the joint body 6. An electric fusion splicing joint is obtained in which the terminal pins 5 of the plug 63 protruding from the outer peripheral surface are connected.

When the synthetic resin pipes are connected to each other by using this electric fusion joint, the ends of the synthetic resin pipes are fitted into the respective receptacles 61 and then the power cords are connected to the terminal pins 5 to connect the heating wires 4 to each other. Heat up. Then, the inner peripheral surface of the receiving port 61 and the outer peripheral surface of the end portion of the synthetic resin pipe are simultaneously melted and fusion-bonded.
In the electric fusion-bonded joint according to the present invention, since the heating wire is embedded in the inner peripheral surface of the receiving port at a constant interval and at a constant depth, the fusion-bonded surface is uniformly melted uniformly to obtain a strong fusion-bonded joint. To be

In the above-mentioned embodiment, the column made of conductive metal is erected on the outer peripheral surface of the synthetic resin ring body, but the column is integrally made of the same kind of synthetic resin as the ring body. It may be injection molded. In this case,
The terminal pin may be attached to the support of the ring body, and the end of the heating wire may be connected and fixed to the terminal pin.

[0016]

As described in detail above, according to the present invention, since the ring body made of synthetic resin is externally fitted to the core and the terminal pins are attached to the columns of the ring body, the mold closing can be performed very easily. The molding cycle can be significantly shortened as compared with the conventional manufacturing method, and the automation of joint manufacturing becomes extremely easy. In addition, since the heating wire covered with insulating resin is wound around the outer peripheral surface of the core, adjacent heating wires do not come into contact with each other and short-circuit, and the heating wire has a constant interval and depth on the inner peripheral surface of the receiving port. It is possible to easily manufacture the electric fusion-bonded joint embedded in.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a mold device used in the present invention.

FIG. 2 is a cross-sectional view of an electric fusion joint manufactured according to the present invention.

[Explanation of symbols]

 1 Mold 2 Core 3 Ring Body 4 Heating Wire 32 Strut

Claims (1)

[Claims] Claims: 1. Receptacles are provided at both ends of a synthetic resin joint body, and heating wires are spirally embedded in the inner peripheral surfaces of the respective joints, and both ends of the heating wire are projected on the outer peripheral surface of the joint body. In manufacturing the electric fusion splicer connected with the terminal pin
A method for manufacturing an electric fusion joint, which comprises the following forming steps. First, a synthetic resin ring body with standing columns on the outer peripheral surface is externally inserted to both ends of the core forming the inner peripheral surface of the joint body, and then one end of the heating wire covered with the insulating resin is attached to one ring. After wrapping the heating wire around the outer surface of the core between the ring body and the other ring body, tie the other end of the heating wire to the other ring body struts, After that, attach the terminal pins to the columns of each ring body, cover the outer peripheral side of the core with an outer mold that can be divided, close the mold, and then inject the molten resin into the cavity formed by the outer mold and the core. ,