JPH0739119B2 - Manufacturing method of welded joint - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a joint for welding and joining a synthetic resin gas pipe or a water pipe.

(Prior Art) Conventionally, as a method for manufacturing a branch joint for welding and joining synthetic resin pipes, for example, a method described in JP-A-58-65624 is known.

In this conventional method, a sheet forming step of forming a resin sheet having a spiral groove on one surface, a conductive wire inserting step of inserting a conductive wire into the groove of the resin sheet, and fixing so that the conductive wire does not deviate from the groove The step of fixing the conductive wire, the step of installing the mat completed in the above step on the core of the mold, and the step of molding the joint by injection of the thermoplastic resin into the mold with the core installed in the mold It was composed of a process and.

(Problems to be solved by the invention) However, in such a conventional method for manufacturing a welded joint, since the manufacturing process is complicated and labor-intensive, tension is applied to the conductive wire in the conductive wire insertion step,
There is a problem that the conductive wire is easily broken.

The present invention pays attention to the above problems, can simplify the manufacturing process and can manufacture a welded joint in a short time, and can prevent disconnection and can reliably manufacture a joint having a welding function. It provides a method.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the method for manufacturing a welded joint of the present invention is A method for manufacturing a welded joint in which a conductive material is disposed on an inner peripheral portion, wherein a core having an inner peripheral molding surface for molding an inner peripheral surface of a joint main body is provided as a mold of the joint. Using a mold, and using a conductive nonwoven fabric as the conductive material, the conductive nonwoven fabric is placed on the inner peripheral molding surface of the core, and after the step,
A molding step of filling the mold with a thermoplastic resin and performing injection molding.

The conductive non-woven fabric used in the present invention is preferably a paper sheet containing a conductive fiber, the conductive fiber alone or a mixture of the conductive fiber and the non-conductive fiber in a suitable liquid medium such as water. It is obtained by dispersing, making up with an appropriate binder, fixing the fibers by adhesion, and forming a nonwoven fabric.

Here, the electrically conductive fiber preferably has an electrical resistance of 10 ⁻² Ωcm or less, and examples thereof include metal fiber such as steel fiber and stainless fiber, and carbon fiber, and carbon fiber is preferably used. When the conductive fiber is solely made into paper, the length thereof is 10 to 200 mm, preferably 15 to 100 mm, and when it is out of the above range, it is generally difficult to obtain a paper sheet having a uniform thickness. However, when papermaking is performed using a mixture with non-conductive fibers, the length may be about 3 mm. Further, the thickness of the conductive fiber is too large, a large amount of fiber is required, and it becomes difficult to uniformly disperse it in the medium, and it is not possible to obtain a paper sheet having a uniform basis weight distribution. Or less, preferably
It is 25 μ or less.

The basis weight of the paper sheet thus obtained is 10 to 500 g.
/ m ² , preferably 20 to 300 g / m ² .

(Operation) When manufacturing the welded joint, a conductive non-woven fabric having a shape corresponding to the inner peripheral surface of the joint body is used, and the conductive non-woven fabric is installed on the inner peripheral molding surface of the core of the mold.

Next, the core is set at a predetermined position of the mold, the molten thermoplastic resin is filled in the mold, and the joint is injection-molded.

In the joint manufactured in this manner, the conductive non-woven fabric is arranged in the inner peripheral portion of the joint main body, and a constant voltage is applied to the conductive non-woven fabric in a state where the synthetic resin pipe is inserted inside the joint main body. It is possible to weld and join synthetic resin pipes by energizing over them.

(Examples) Examples of the present invention will be described in detail below with reference to the drawings.

First, the structure of the first embodiment shown in FIGS. 1 to 8 will be described.

In this embodiment, the socket A as shown in FIG. 7 is taken as an example of the joint, and the manufacturing method of the socket A will be described.

In the method of manufacturing the socket A of this embodiment, the mold 1
The conductive nonwoven fabric 2 and the resin sheet 3 are used.

The mold 1 includes a first outer mold 11 as shown in FIGS.
And a second outer die 12, and a core (inner die) 13 installed in a space formed by the first outer die 11 and the second outer die 12. The outer peripheral molding surface 11 for molding the outer peripheral surface of the socket body 10 is provided on the facing surfaces of the first outer mold 11 and the second outer mold 12.
a and 12a are formed, and the inner peripheral molding surface 13a for molding the inner peripheral surface of the socket body 10 is formed on the outer peripheral surface of the core 13.
Are formed. The core 13 has outer peripheral molding surfaces 11a and 12a.
It is installed so that a constant gap 14 is secured between the inner peripheral molding surface 13a and the inner peripheral molding surface 13a.

As the conductive nonwoven fabric 2, for example, carbon fiber is used. As shown in FIG. 1, the conductive non-woven fabric 2 is cut into a rectangular shape having a thickness of 0.5 to 1.0 mm, and is preferably punched uniformly at an area ratio of 20 to 40%.
21 is opened. The punch hole 21 is given a circular shape, an elliptical shape, a quadrangular shape, or the like.

The resin sheet 3 is made of, for example, a thermoplastic resin such as polyethylene and has a substantially same shape as the conductive nonwoven fabric 2 and is formed into a sheet shape having a thickness of 0.3 to 0.8 mm.

Next, a method of manufacturing the socket A using these will be described. This manufacturing method is performed in the order of an installation step and a molding step.

(Installation process) First, the resin sheet 3 and the conductive non-woven fabric 2 are placed on the resin sheet 3
Is placed on the inner peripheral molding surface 13a of the core 13 with the inside facing. The resin sheet 3 and the conductive nonwoven fabric 2 are installed by winding them around the core 13 (see FIGS. 2 and 3).

After installing the resin sheet 3 and the conductive nonwoven fabric 2 on the core 13,
The terminal pin 4 is set using the fixing jig 15 so that the lower part of the conductive non-woven fabric 2 contacts the conductive non-woven fabric 2 (see FIG. 4).
Two terminal pins 4 are installed at both ends of the conductive nonwoven fabric 2.

The terminal pin 4 and the conductive non-woven fabric 2 may be connected using a conductive wire.

(Molding Step) Next, the core 13 is installed at a predetermined position of the mold 1, and the thermoplastic resin of the same material as the resin sheet 3 is placed in the gap 14 between the core 13 and the first outer mold 11 and the second outer mold 12. Filling and injection molding,
Reference numeral 15 is a fixing jig for fixing the terminal pin 4 at a predetermined position, which is fixed to the core 13 in advance and installed in the mold 1 integrally with the core 13 (see FIGS. 5 and 6). ).

The resin is injected into the gap 14 from the spool 16 and is also filled in the punch holes 21 of the conductive nonwoven fabric 2.

At this time, the pressure generated by the injection of the resin ensures the winding of the resin sheet 3 and the conductive nonwoven fabric 2 around the core 13. Then, the socket body 10 is molded on the outer side of the conductive nonwoven fabric 2.

The resin material filled in the gap 14 is not necessarily the same as the material of the resin sheet 3, and different types of resins may be combined as long as they are compatible with each other. As a combination of compatible resins, for example, ABS resin is used for the resin sheet 3 and PVC resin is used for the socket body 10, or PVC elastomer resin is used for the resin sheet 3 and PVC resin is used for the socket body. The combination etc. used for 10 are mentioned.

The socket A is manufactured through the above steps.

Since the conductive nonwoven fabric 2 is used in the manufacturing method of the present embodiment, the conductive wire insertion (or winding) step and the conductive wire fixing step, which have been performed by the conventional method, can be omitted, and the manufacturing process is greatly simplified. can do.

Further, in the socket A manufactured by the method of this embodiment, as shown in FIG. 7 and FIG. 8, the conductive nonwoven fabric 2 is laminated on the inner peripheral portion of the socket body 10 by the inner layer material 101 and the outer layer material 102. It is arranged by. And these inner layer materials 101
The outer layer material 102 and the outer layer material 102 are connected to each other by a plurality of pillar portions 103 formed of resin filled in the punch holes 21 of the conductive nonwoven fabric 2.

In this way, the conductive nonwoven fabric 2 is laminated with the inner layer material 101 and the outer layer material 102, and the inner layer material 101 and the outer layer material 102 are composed of a plurality of pillars.
Since they are connected by 103, there is no risk of peeling from the socket body 10.

In addition, the socket A is a synthetic resin pipe by applying a constant voltage from the terminal pins 4 and 4 to the conductive non-woven fabric 2 with the synthetic resin pipe (not shown) inserted inside the end. However, since the conductive nonwoven fabric 2 is used, it is possible to reliably energize and to weld the synthetic resin pipes to each other.

Next, a second embodiment shown in FIGS. 9 to 13 will be described.

In this embodiment, a branch joint B as shown in FIG. 13 is taken as an example of the joint, and a method for manufacturing the branch joint B will be described.

The die 5 used for manufacturing the branch joint B includes a female die 51 and a core 51 as shown in FIG. 12, and the female die 51 is
The upper mold 511, the first slide mold 512, and the second slide mold 513 are included.

In the branch joint B, a branch connecting portion 40 is provided in the middle of a joint body 30 having a saddle portion 20, and the first slide die 512 and the second slide die 513 are joint bodies with respect to the upper die 511. The core 52 is installed through a molding gap 53.
Is installed with respect to the first slide mold 512 and the second slide mold 513 via a gap 54 for molding the joint body. Further, the second slide mold 513 is formed with a gap 55 for molding a branch connection portion, which is continuous with the gap 54 for molding the joint body. Incidentally, 52a is a saddle portion inner peripheral molding surface for molding the inner peripheral surface of the saddle portion 20.

Further, as the conductive non-woven fabric 6 and the resin sheet 7, those which are formed in a donut shape as shown in FIG. 9 are used.
Incidentally, 61 is a punch hole.

The manufacturing method is performed in the order of the installation step and the molding step, as in the method of manufacturing the socket A described in the first embodiment.

The details are shown only in the drawings, and the description thereof is omitted.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope not departing from the gist of the present invention, it is included in the present invention. Be done.

For example, in the examples, in forming the branch joint, a conductive non-woven fabric cut in a donut shape was used,
You may use electroconductive nonwoven fabrics, such as an ellipse and a square.

Further, in the embodiment, the resin sheet is installed inside the conductive nonwoven fabric in the step of installing on the core, but only the conductive nonwoven fabric may be installed on the core without using the resin sheet. In this case, a joint in which the conductive nonwoven fabric is exposed on the inner peripheral surface is obtained. In this case, it is preferable to prevent the peeling from the joint body by providing a plurality of punch holes in the conductive nonwoven fabric.

(Effects of the Invention) As described above, in the method for manufacturing a welded joint of the present invention, since the manufacturing process is greatly simplified,
A welded joint can be manufactured efficiently in a short time with good productivity.

Further, since the conductive non-woven fabric is used, it is possible to manufacture a fusion-bonded joint which can surely weld-bond the synthetic resin pipes without disconnection.

[Brief description of drawings]

FIG. 1 is a view showing a conductive non-woven fabric used in a method for manufacturing a socket according to a first embodiment of the present invention, FIGS. 2 to 6 are sectional views for explaining the method of the first embodiment, and FIG. FIG. 8 is a vertical sectional view showing a socket manufactured by the embodiment method, and FIG.
FIG. 9 is an enlarged view of an essential part, FIG. 9 is a view showing a conductive non-woven fabric used in a method for manufacturing a branch joint according to a second embodiment of the present invention, and FIGS. 10 to 12 are cross-sectional views for explaining the second embodiment method. FIG. 13 and FIG. 13 are longitudinal sectional views showing a branch joint manufactured by the method of the second embodiment. A …… Socket (fitting) 10 …… Socket body (fitting body) B …… Branch fitting (fitting) 30 …… Fitting body 1,5 …… Mold 13,52 …… Core 13a, 52a …… Inner peripheral molding Surface 2, 6 ... Conductive non-woven fabric

Claims (1)

[Claims] 1. A method for manufacturing a welded joint in which a conductive material is arranged on the inner peripheral portion of a joint body, wherein an inner peripheral molding surface for molding the inner peripheral surface of the joint body is used as a mold of the joint. Using a mold provided with a core having, and using a conductive non-woven fabric as the conductive material, and placing the conductive non-woven fabric on the inner peripheral molding surface of the core, and after the process, the mold And a molding step of performing injection molding by filling a thermoplastic resin therein.