JPH0230508A - Manufacture of weld joint - Google Patents

Abstract

PURPOSE:To arrange a conductive wire in an inner circumferential part of a joint body at a uniform depth and fixed space, by a method wherein a coated conductive wired is heated, wound spirally round an inner circumferential molding surface of a core while melting a thermoplastic resin layer, and thermoplastic resin is injection-molded within a mold. CONSTITUTION:A coated conductive wire 2 is supplied to a heater 3 from a bobbin 4, the coated conductive wire 2 is heated and wound spirally round an inner circumferential molding surface 12a of a core 12 at fixed tension while melting its thermoplastic resin layer 22. Since the thermoplastic resin layers 22 are welded to each other at parts of a coated conductive wire 2 adjoining to each other following to winding-up, the one coated conductive wire 2 is formed cylindrically after completion of the winding-up. The core 12 is arranged at a fixed position of a mold 1, a gap 13 between an outer tool 11 and the core 12 is filled with thermoplastic resin of the same material as the thermoplastic resin layer 22 of the coated conductive wire 2 and injection molding is performed. The filled out thermoplastic resin is unified with the resin of the thermoplastic resin layer 22 of the coated conductive wire 2 by becoming soluble in each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a joint for welding and joining synthetic resin gas pipes and water pipes.

(Prior Art) Conventionally, as a method for manufacturing a joint for joining synthetic resin pipes by welding, a method as described in, for example, Japanese Unexamined Patent Publication No. 59-13180 is known.

This conventional method includes a cylindrical body forming step of molding a cylindrical cylindrical body, an installation step of installing the cylindrical body in the core of a mold,
The winding process involves wrapping a heated conductive wire around the outer periphery of the cylindrical body, installing the core with the conductive wire and the cylindrical body in a mold, and filling the mold with thermoplastic resin to form the joint. It consisted of a joint forming process using injection molding.

(Problem to be solved by the invention) However, in such conventional manufacturing methods,
In the winding process, the conductive wire was heated, the outer periphery of the cylindrical body was melted by the heat of the conductive wire, and the conductive wire was encapsulated in the cylindrical body as it was wound, resulting in variations in temperature and tension of the conductive wire. Therefore, there was a problem in that the depth of encapsulation of the conductive wires varied. That is, a welded joint is manufactured in which the conductive wire is buried at a non-uniform depth in the inner circumference of the joint body.

Also, it requires sophisticated techniques to wrap conductive wires at regular intervals, and short circuits may occur if sufficient care is not taken.

As described above, welded joints in which conductive wires are buried at uneven depths or arranged at uneven intervals have the problem that it is difficult to obtain a uniform welded state when welding them to synthetic resin pipes. was there.

Furthermore, this conventional method was comprised of a cylindrical body forming process, an installation process, a winding process, and a joint forming process, and the manufacturing process was complicated, requiring a lot of manufacturing effort.

The present invention focuses on the above-mentioned problems, and provides a method for manufacturing a welded joint that simplifies the manufacturing process, allows conductive wires to be buried at a uniform depth in the inner circumference of the joint body, and can be arranged at regular intervals. It provides:

(Means for Solving the Problems) The present invention was made for the purpose of solving the problems such as "double series", and in order to achieve this purpose, the method for manufacturing a welded joint of the present invention A method for manufacturing a welded joint in which a heating element is embedded in the inner periphery of a main body, which includes: a mold provided with a core having an inner periphery forming surface for forming the inner periphery of the joint main body; and a conductive mold as a heating element. Wrapping in which the coated conductive wire is coated with a thermoplastic resin layer, and the coated conductive wire is heated to melt the thermoplastic resin layer while being wound spirally around the inner molded surface of the core. This method consists of a molding step in which a thermoplastic resin is filled into a mold in which a core around which a coated conductive wire is wound is installed, and injection molding is performed.

(Function) In manufacturing a welded joint, first the coated conductive wire is heated and the thermoplastic resin layer is melted and wound spirally around the inner molded surface of the core.

During winding, the thermoplastic resin layers of adjacent portions of the covered conductive wire are welded to each other, so that the coated conductive wire is formed into a cylindrical shape after winding is completed.

Here, the distance between the inner peripheral molded surface of the core and the conductive wire and the winding interval of the conductive wire are determined by the thickness of the thermoplastic resin layer and are therefore always kept constant.

(Wrapping process).

Next, the core around which the coated conductive wire is wound is placed in a predetermined position in a mold, the mold is filled with a molten thermoplastic resin, and the joint is injection molded (molding process).

In this way, it is possible to manufacture a welded joint in which the conductive wires are buried at a uniform depth in the inner circumference of the joint body and are arranged at regular intervals.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the first embodiment shown in FIGS. 1 to 3 will be explained.

In this embodiment, a socket A as shown in FIG. 3 is taken as an example of a joint, and a method of molding this socket A will be explained.

In the method for manufacturing socket A of this embodiment, a mold 1,
A covered conductive wire 2 and a heater 3 are used.

As shown in FIG. 6, the mold 1 includes, for example, an outer mold 11 and a core (inner mold) 12 that are divided into two parts. An outer peripheral molding surface 11a for molding the outer peripheral surface of the socket main body 10 is formed inside the outer mold 11, and an outer peripheral molding surface 11a for molding the outer peripheral surface of the socket main body 10 is formed on the outer peripheral surface of the core 12. An inner peripheral molding surface 12a is formed. Furthermore, core 12
is installed in the mold l so that a certain gap 13 is secured between the outer peripheral molding surface 11a and the inner peripheral molding surface L2a. Further, the material of the core 12 is preferably one having high thermal conductivity, such as aluminum.

The covered conductive wire 2 is a conductive wire 21 made of a Cu wire or the like as a heating element and covered with a thermoplastic resin layer 22 such as a polyethylene resin.

Note that the thermoplastic resin layer 22 is not limited to polyethylene resin, and thermoplastic resins such as polypropylene resin, polyvinyl chloride resin, or polybutene can be used. The coating thickness is preferably 04 to 1.0 mm.

Further, the conductive wire 21 is not limited to a Cu wire, but also a Ni wire M n N
i alloy wire etc. can be used. Its diameter is 02~
0.9 mm is desirable.

Next, a method of manufacturing socket A using these will be explained. This manufacturing method is performed in the order of a winding process and a molding process.

(Winding process) First, the coated conductive wire 2 is supplied from the pobbin 4 to the heater 3,
While heating the coated conductive wire 2 and melting the thermoplastic resin layer 22 using the heater 3, the inner peripheral molding surface 12 of the core I2 is heated.
Wrap it spirally around a with a constant tension (see Figure 1).

As the winding is completed, the thermoplastic resin layers 22 of adjacent portions of the covered conductive wire 2 are welded to each other, so that the coated conductive wire 2 is formed into a cylindrical shape after winding is completed.

Here, the distance between the inner peripheral molding surface 12a of the core 12 and the conductive wire 21 and the winding interval of the conductive wire 21 are determined by the thermoplastic resin layer 2
Since it is determined by the thickness of 2, it is always kept constant.

(Molding process) Next, the terminal pins 6 are connected to both ends of the conductive wire 2 by the fixing jig 5, and the core 12 provided with the covered conductive wire 2 and the terminal pins 6 is installed in a predetermined position of the mold 1. Then, the gap 13 between the outer mold 11 and the core 12 is filled with thermoplastic resin of the same material as the thermoplastic resin layer 22 of the covered conductive wire 2, and injection molding is performed. (See FIG. 2) The filled thermoplastic resin is compatible with and integrated with the resin of the thermoplastic resin layer 22 of the coated conductor II2.

The thermoplastic resin filled in the gap 13 does not necessarily have to be the same material as the thermoplastic resin layer 22 of the covered conductive wire 2, as long as they are compatible with each other.
Different types of resins may be combined. Examples of combinations of compatible resins include using ABS resin for the thermoplastic resin layer 22 and using PVC resin for the socket body 10, or using PVC elastomer resin for the thermoplastic resin layer 22 and pvce. Another example is a combination in which fat is used for the socket body IO.

Through the above steps, the socket A in which the conductive wire 21 is embedded in the inner circumference of the socket body 10 is manufactured (third
(see figure).

In the method of this embodiment, since the coated conductive wire 2 is wound around the core 12 in the winding process, a socket A is manufactured in which the conductive wire 21 is buried at a uniform depth throughout and is placed at regular intervals. be able to.

As shown in FIG. 3, this socket A is a synthetic resin pipe P.
is inserted into the inside of the end, a constant voltage is applied from the terminal pin 6 to generate heat in the conductive wire 21, and the inner circumference of the socket A and the outer circumference of the synthetic resin pipe P are melted, and the socket is closed. It is possible to weld and join A and the synthetic resin pipe P to each other. As described above, in the socket A, the conductive wire 21 is buried at a uniform depth throughout, and
Since they are arranged at regular intervals, the inner peripheral part of the socket A and the outer peripheral part of the synthetic resin pipe P can be uniformly melted, thereby achieving a uniform welded state.

In addition, the method of this embodiment can eliminate the cylindrical body forming step and the installation step in the conventional method, so by simplifying the manufacturing process, welded joints can be manufactured efficiently in a short time with high productivity. I can do it.

Next, a manufacturing method of the second embodiment shown in FIG. 4 will be explained.

In the method of this embodiment, the coated conductive wire 2 is wound around the inner molded surface 12a of the core 12 while the core 12 is heated in the winding step. The thermoplastic resin layer 22 is melted and adjacent portions are welded together.

In addition, the next molding process and the mold 1 used in this molding process
etc. are the same as those in the first embodiment, so drawings and explanations will be omitted. Furthermore, since the operation is similar to that of the first embodiment, the explanation will be omitted.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, a socket is used as an example of a joint, but by changing the shape of the core, the present invention can also be applied to manufacturing elbows, cheeses, reducers, etc. other than sockets.

(Effects of the Invention) As explained above, in the method for manufacturing a welded joint of the present invention, conductive wires can be buried at a uniform depth in the inner circumference of the joint body, and can be arranged at regular intervals. Therefore, it is possible to manufacture a welded joint that can obtain a uniform welded state when welded and joined to a synthetic resin pipe.

Furthermore, since the manufacturing process is greatly simplified, welded joints can be manufactured efficiently and with high productivity in a short period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating the winding process in the socket manufacturing method according to the first embodiment of the present invention, FIG. 2 is a longitudinal sectional view illustrating joint forming in the direction of the first embodiment, and FIG. FIG. 4 is a longitudinal sectional view showing a socket manufactured by the method of the second example, and a perspective view illustrating the winding step in the method of the second example. A...-Socket (joint) 10...-Socket body (joint body) L...-Mold 12--Core 12a--Inner periphery molding surface 2--Coated conductive wire 21--Conductive wire 22...Thermoplastic resin layer patent application Hiro 1) Kaoru Sekisui Chemical Co., Ltd. Representative

Claims (1)

[Claims] 1) A method for manufacturing a welded joint in which a heating element is embedded in the inner periphery of a joint body, comprising: a core having an inner periphery molding surface that molds the inner periphery of the joint body. Using a mold and a coated conductive wire as a heating element, in which the conductive wire is covered with a thermoplastic resin layer, the coated conductive wire is heated and the thermoplastic resin layer is melted while being applied to the inner peripheral molding surface of the core. It is characterized by consisting of a winding process in which the wire is wound spirally, and a molding process in which a thermoplastic resin is filled into a mold in which a core around which the coated conductive wire is wound is installed and injection molding is performed. Method of manufacturing welded joints.