JPH08338587A - Covered electric heating wire and manufacture of electrofusion joint using same - Google Patents

Abstract

PURPOSE: To provide a covered electric heating wire which can easily integrally incorporate a covered electric heating wire wound in a coil-like shape. CONSTITUTION: A covered electric heat wire 1 is composed of a ridge 4 formed on the outer surface of a resin layer 3 with which an electric heat wire is covered, and a groove 5 formed in the outer surface of the resin layer 3 on the side remote from the ridge 4, for receiving the ridge 4, the ridge 4 and the groove 5 extending in the longitudinal direction of the electric heating wire 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated heating wire coated with a synthetic resin and a method for producing an electrofusion joint using the same.

[0002]

2. Description of the Related Art An electrofusion joint has been recently developed as a pipe joint for plastic pipes used for water and sewer pipes and gas pipes. This joint consists of a molded product in which a coated heating wire that generates heat when energized is coiled and embedded inside.To connect with a pipe, insert the pipe from both sides of the joint and energize to heat and melt the connection surface. It is supposed to be done by doing so. A method for manufacturing such a pipe joint is described in, for example, Japanese Patent Application Laid-Open No. 1-164889.

As a conventional method for manufacturing an electrofusion joint, a coated heating wire is wound on a cylinder in a coil shape so that adjacent heating wires are in close contact with each other, set in a mold, injection molded, and wound on the cylinder. Apply a heater to the heating wire to fuse the surface and integrate it, then pull out from the cylinder,
A method of inserting the obtained coil-shaped heating wire into a pipe joint and assembling it is known.

However, since the above method of applying a heater to the coated heating wire to fuse and fuse them together requires a lot of work, in the method of manufacturing the joint described in the above publication, one of the coated heating wire and the cylinder or By heating both of them to a temperature at which the resin softens, the coated heating wires are brought into close contact with each other. The coated heating wire used in the above conventional manufacturing method has a cross-sectional shape such as a circular shape, a trapezoidal shape, a semicircular shape, or a rectangular shape.

[0005]

However, in the prior art described in the above publication, a special device such as a heating device and a pressing roller for closely contacting with each other is required, and the column is covered with a heating wire so that the heating wire does not adhere to the column. There is a problem in that the manufacturing apparatus is complicated and expensive because it is necessary to take a special treatment to coat the surface of the product with Teflon.

The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a coated heating wire capable of easily integrating a coated heating wire wound in a coil shape. A second object of the present invention is to provide a method of manufacturing an electrofusion joint including a winding process that can easily integrate a coated heating wire wound in a coil shape.

[0007]

The present invention has been made to achieve the above object, and a coated heating wire according to the invention of claim 1 has a convex portion on the surface of a resin layer coated with the heating wire. And a concave portion into which the convex portion can be fitted is provided in the longitudinal direction on the surface of the resin layer opposite to the surface on which the convex portion is provided.

A method for manufacturing an electrofusion joint according to a second aspect of the present invention is a method for manufacturing an electrofusion joint, which comprises a winding step of winding a coated heating wire in a coil shape on an outer peripheral surface of a cylinder or a cylinder. The winding step is characterized in that the coated heating wire according to claim 1 is wound around an outer peripheral surface of a cylindrical body or a cylinder in a coil shape, and a convex portion of the coated heating wire is fitted into a concave portion of an adjacent coated heating wire. It is a thing.

In the method of manufacturing the electrofusion joint according to the second aspect of the present invention, the coated heating wire is wound in a coil shape on the outer peripheral surface of the cylindrical body or the cylinder, and the coiled coated heating wire is extracted from the cylindrical body or the cylinder. It is mounted on a core in a mold and injection-molded, or a cylindrical body or a cylinder is set in the mold while the coated heating wire is wound and injection-molded, or it is extracted from the cylinder or the cylinder. Whether to assemble the coiled heating wire inside the joint, or
Either may be used.

[0010]

According to the coated heating wire of the present invention, a convex portion is formed on the surface of the resin layer coated with the heating wire, and the convex portion is formed on the surface of the resin layer opposite to the surface where the convex portion is provided. Since the recesses that can be fitted are provided in the longitudinal direction, the covered heating wire is wound in a coil shape, and the protrusions of the covered heating wire are fitted into the recesses of the adjacent covered heating wire, so that they are easily integrated. can do.

In the method for manufacturing an electrofusion joint according to the invention of claim 2, in the winding step, the coated heating wire according to claim 1 is wound around the outer peripheral surface of the cylindrical body or the cylinder in a coil shape to form a convex portion of the coated heating wire. Since the wires are fitted in the recesses of the adjacent covered heating wires, the winding step is provided so that the covered heating wires can be easily integrated.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. 1 to 3 show one embodiment of a method for manufacturing a coated heating wire and an electrofusion joint of the present invention, FIG. 1 is a perspective view of the coated heating wire, and FIG. 2 (a) is a front view of a winding machine. FIG. 3B is a side view, FIG. 3A is a cross-sectional view of the coated heating wire wound in a coil shape, and FIG. 3B is an enlarged cross-sectional view of a portion A of FIG. FIG. 4 to FIG. 7 are cross-sectional views of coated heat insulating wires having different shapes, which are other embodiments of the coated heating wire of the present invention.

First, an embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 is a coated heating wire, 2 is a heating wire, 3 is a resin layer, 4 is a convex portion, 5 is a concave portion, and 6 is a cylindrical body. As shown in FIG. 1, the coated heating wire 1 has a substantially T-shaped convex portion 4 continuously provided in the longitudinal direction on the surface of the resin layer 3 covering the heating wire 2. A substantially T-shaped concave portion 5 is continuously provided in the longitudinal direction on the surface of the resin layer 3 opposite to the surface on which the convex portion 4 is provided, and the inner peripheral surface of the concave portion 5 is formed. The shape of is substantially the same as the shape of the outer peripheral surface of the convex portion 4, and the convex portion 4 can be fitted into the concave portion 5.

The heating wire 2 generates heat when energized by a nichrome wire or the like, and the resin layer 3 covering the periphery of the heating wire 2 is made of a synthetic resin such as polyethylene, polybutene, polypropylene or the like. . The cross-sectional shape of the resin layer 3 is a substantially quadrangular shape, but it may be a semi-cylindrical shape whose upper side is an arc, a rhombic shape, or a circular shape.

The coated heating wire 1 shown above is wound into a coil by the winding machine shown in FIG. In this winding machine, a rotary shaft 7 is provided at one end of a cylindrical body 6, and the cylindrical body 6 can be rotated via the rotary shaft 7 by a drive device (not shown). An insertion hole 8 is formed on the outer peripheral surface of the cylindrical body 6, the resin layer 3 at the end of the coated heating wire 1 is removed to expose the heating wire 2, and the exposed heating wire 2 is inserted into the insertion hole. 8 and insert a wedge (not shown) to fix it.

Next, the cylindrical body 6 is rotated and the coated heating wire 1 is wound around the outer peripheral surface of the cylindrical body 6 so as to be adjacent to each other in a coil shape, and the convex portion 4 of the coated heating wire 1 is formed adjacent to the coated heating wire 1. Recess 5
Fit in. At this time, when the convex portion 4 is pressed against the concave portion 5 and wound while being fitted, the adjacent covered heating wires 1 can be easily integrated. Alternatively, once the coated heating wire 1 is wound around the outer peripheral surface of the cylindrical body 6, the convex portion 4 is replaced by the concave portion 5
Even if it is driven into and fitted in, it can be easily integrated.

Coated heating wire 1 wound in the above coil shape
As shown in FIG. 3, since the convex portion 4 is fitted in the concave portion 5, the convex portion 4 does not come apart even if it is extracted from the cylindrical body 6. The work of fusing and fixing can be omitted.

Connecting terminals are attached to both ends of the coiled heating wire 1 obtained in the above winding step, the coated heating wire 1 is attached to the core in the mold, and the connecting terminals are held to secure the connection of polyethylene or the like. By injection molding a synthetic resin, it is possible to obtain an electrofusion joint in which the coated heating wire is embedded in the inner peripheral surface.

At this time, the cylindrical body 6 is set in a mold while the coated heating wire 1 is wound and injection molding is performed, or alternatively, the coiled coated heating wire 1 extracted from the cylindrical body 6 is provided in a joint. Also, as a method of assembling, the coated heating wire 1 is integrated with each other, so that the electrofusion joint can be manufactured without any trouble.

Next, another embodiment of the coated heating wire of the present invention will be described with reference to FIGS. Covered heating wire 1 of FIG.
In a, the resin layer 3a covering the heating wire 2a has a semi-cylindrical cross section, and an arrow-shaped convex portion 4a is continuously provided in the longitudinal direction on the surface of the resin layer 3a. Further, a concave portion 5a in the shape of an arrow, into which the convex portion 4a can be fitted, is continuously provided in the longitudinal direction on the surface of the resin layer 3a opposite to the surface on which the convex portion 4a is provided. .

When the coated heating wire 1a is wound into a coil in the same manner as in the above embodiment and the convex portion 4a is fitted into the recess 5a of the adjacent coated heating wire 1a, the coiled coated heating wire is easily integrated. The heating wire 1a can be obtained.

In the coated heating wire 1b shown in FIG. 5, the resin layer 3b covering the heating wire 2b has a quadrangular cross section, and the resin layer 3b has a substantially L-shape downward from the upper edge of the surface thereof. Convex portion 4b is continuously provided in the longitudinal direction. Then, a concave portion 5b into which the convex portion 4b can be fitted is provided continuously in the longitudinal direction from the lower end edge of the surface of the resin layer 3b opposite to the surface on which the convex portion 4b is provided, to the upper side. There is.

The coated heating wire 1c shown in FIG.
The resin layer 3c covering c has a quadrangular cross-sectional shape, and a substantially L-shaped convex portion 4c is continuously provided in the longitudinal direction downward from the upper edge of the surface of the resin layer 3c. There is. Further, a concave portion 5c is continuously provided in the longitudinal direction from the central portion of the surface of the resin layer 3c on the side opposite to the surface on which the convex portion 4c is provided, to the upper side.

Further, in the coated heating wire 1d shown in FIG. 7, the resin layer 3d covering the heating wire 2d has a quadrangular cross-section, and the resin layer 3d is substantially downward from the center of the surface of the resin layer 3d. The L-shaped convex portion 4d is continuously provided in the longitudinal direction. A recess 5d is continuously provided in the longitudinal direction from the lower end of the surface of the resin layer 3d opposite to the surface on which the projection 4d is provided, upward.

The coated heating wire 1b shown in FIGS.
In the same manner as in the above-mentioned embodiment, each of 1c and 1d is wound in a coil shape, and when the respective convex portions are fitted into the concave portions of the adjacent covered heating wire, the coiled covered heating wire is easily integrated. be able to.

[0026]

The coated heating wire according to the invention of claim 1 is easily integrated by winding the coated heating wire in a coil shape and fitting the convex portion of the coated heating wire into the concave portion of the adjacent coated heating wire. As a result, it is possible to save the time and labor required to fuse the coating resin layers to each other by using an electric trowel or a heater as in the prior art, and to improve work efficiency.

In the method for manufacturing an electrofusion joint according to the second aspect of the present invention, the winding step includes winding the coated heating wire according to claim 1 in a coil shape around the outer peripheral surface of the cylindrical body or column to form a convex portion of the coated heating wire. Since it is equipped with a winding process that fits in the recess of the adjacent covered heating wire and can easily integrate the covered heating wire, the equipment for the winding process should be relatively simple and compact. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a perspective view of a coated heating wire according to an embodiment of the present invention.

FIG. 2A is a front view of the winding machine, and FIG. 2B is a side view.

3A is a cross-sectional view of a coated heating wire wound in a coil shape, and FIG. 3B is an enlarged cross-sectional view of a portion A of FIG.

FIG. 4 is a cross-sectional view of covered insulation wires having different shapes.

FIG. 5 is a cross-sectional view of covered insulation wires having different shapes.

FIG. 6 is a cross-sectional view of covered insulation wires having different shapes.

FIG. 7 is a cross-sectional view of covered insulation wires having different shapes.

[Explanation of symbols]

 1, 1a, 1b, 1c, 1d Covered heating wire 2, 2a, 2b, 2c, 2d Heating wire 3, 3a, 3b, 3c, 3d Resin layer 4, 4a, 4b, 4c, 4d Convex portion 5, 5a, 5b 5c, 5d recess 6 cylinder

Claims (2)

[Claims] 1. Longitudinal portions each having a convex portion on a surface of a resin layer coated with a heating wire and a concave portion capable of fitting the convex portion on a surface of a resin layer opposite to a surface on which the convex portion is provided. Covered heating wire characterized by being provided in the direction. 2. A method for manufacturing an electrofusion joint, comprising a winding step of winding a coated heating wire around an outer peripheral surface of a cylindrical body or a cylinder in a coil shape, wherein the winding step is the coated heating wire according to claim 1. Is wound around the outer peripheral surface of a cylindrical body or a cylinder in a coil shape, and the convex portion of the coated heating wire is fitted into the concave portion of the adjacent coated heating wire.