JPH0584829A - Method of joining pipe body - Google Patents

Abstract

PURPOSE:To provide a pipe joining method capable of joining heat resistance thermoplastic resin pipe bodies accurately and easily. CONSTITUTION:An annular magnetic body 1 is interposed between a pipe body 2 and a pipe body 3, and the pipe 2 is arranged with an inductance coil 4 at the outside or Inside thereof, wherein a high-frequency magnetic field is generated by a high-frequency oscillator and, by the heating of the magnetic body 1, the heat-melted parts are joint-welded while the pipe end surfaces are heat- melted or after heat-melted, subsequently subjected to a cool-hardening process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining heat-resistant thermoplastic resin pipes mainly used in the plant field.

[0002]

2. Description of the Related Art As one of the methods for joining pipes, as shown in FIG. 4, the pipes 2 and 3 are brought into close contact with the left and right sides of a heated hot plate 9, and the end faces of the pipes 2 and 3 are softened and melted. The butt welding method in which the melted portions are pressure-bonded to each other and then cooled and solidified is widely used for joining a polyethylene resin pipe for gas or the like.

[0003]

The hot plate used in this butt welding method is made of polytetrafluoroethylene resin (PTF) to prevent molten resin from adhering to it.
A non-adhesive fluororesin or the like such as E) is coated.

However, polyetheretherketone resin (PEEK), polyphenylene sulfide resin (PP
The melting temperature of the heat resistant thermoplastic resin such as S) is higher than the melting temperature of the coated fluororesin, so that it is not appropriate to use this hot plate as a hot plate for butt welding of the heat resistant thermoplastic resin or the like. ..

As a means for solving this problem, the tubes 2 and 3 are placed in the vicinity of the heating plate 10 without directly contacting the tubes 2 and 3 with the heating plate 10, and the end faces are heated by convection of heat. ,
A method of pressure-bonding the melted portion (FIG. 5) (JP-A-1-123).
No. 728) is considered, but in this case, the heating temperature of the hot plate needs to be set considerably higher than the melting temperature of the resin, and the heating time also becomes long. Further, with such a heating method, it is difficult to accurately control changes in the outside air temperature that greatly affect the temperature rise of the tube end surface, the distance between the hot plate and the tube, the direction of convective heat flow, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide a joining method of pipes which can join the pipes made of heat resistant thermoplastic resin accurately and easily.

[0007]

According to the method of joining pipes of the present invention, an annular magnetic body is provided between the pipes, and an induction coil is arranged inside or outside the pipes, and a high frequency wave is provided. A high-frequency magnetic field is generated by a transmitter, and the tube end surface is heated and melted by heat generation of a magnetic material, or after heating and melting, the melted portion is butt-welded and then cooled and solidified. ..

In the present invention, the tubular body means a pipe or a pipe joint. Examples of the material of the tubular body used in the present invention include polyether ether ketone resin (PEEK), polyphenylene sulfide resin (PPS), polyether sulfone resin (PES), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT). ), A polyimide resin (PI), a polysulfone resin, or the like is preferably used as the heat-resistant thermoplastic resin.

Vinyl chloride resin (PVC), polypropylene resin (PP), polyethylene resin (PE), A
It can also be used for a general-purpose thermoplastic resin such as BS resin (ABS), or a composite material or polymer alloy in which a filler or the like is filled in the general-purpose thermoplastic resin.

Ferromagnetic materials such as iron, stainless steel, iron alloys and aluminum are preferably used as the material of the magnetic material. In addition to this, as the magnetic body, 1) one in which the same kind of thermoplastic resin as the thermoplastic resin pipe body to be joined is coated on the outside of an annular body made of iron, stainless steel, iron alloy, aluminum, etc. 2) iron, stainless steel, iron alloy,
A spherical or fibrous filler made of aluminum or the like may be mixed with a thermoplastic resin of the same kind as the thermoplastic resin tube to be joined, and molded into an annular body.

As the shape of the magnetic body, it is desirable that the rod-like body having a circular or rectangular cross section is formed into an annular shape. As a method of providing the magnetic body between the pipe bodies, a groove is provided at the center of the joint surface of the pipe bodies, or a protrusion for disposing the magnetic body is provided on the pipe body. It is desirable to do.

Further, it is desirable that the magnetic body is arranged so as to be located in the central portion of the tube thickness of the tube body. The shape of the induction coil may be a single-turn type, a multi-turn type, a hairpin type, a pancake type, or the like.

[0013]

The magnetic material is heated by the high-frequency magnetic field generated by the high-frequency oscillator, and the end surface of the tubular body is heated and melted. The end faces of the heat-melted pipes are butted against each other to join the pipes.

Since the magnetic body generates heat without coming into contact with the heat source, the heat source and the pipe body do not come into contact with each other, and problems such as adhesiveness between the heat source and the pipe body or releasability do not occur. Further, since the magnetic body is provided between the pipe bodies, the magnetic body is hardly affected by the outside air temperature, and the pipe body is uniformly heated in the circumferential direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pipe connecting method of the present invention will be described below with reference to the drawings. 1 and 2 show respective embodiments of the tube connecting method of the present invention. FIG. 1 shows the case where the induction coil is arranged inside the tube, and FIG. 2 shows the induction coil outside the tube. FIG. 6 is a partial cross-sectional view of an example in which it is arranged in the.

In FIG. 1, reference numerals 2 and 3 denote pipes to be joined, and an annular groove 8 is formed in each of the central portions of the pipes 2 and 3 in the pipe thickness.
Is provided. Reference numeral 1 is an annular magnetic body made of iron, which is a tubular body 2.
It is placed in the groove 8 of 3 and is sandwiched by the tubes 2, 3.

Reference numeral 4 is an induction coil, which is arranged inside the tubes 2 and 3 by a known method and is connected to a high-frequency oscillator (not shown). Next, a method of joining the pipe bodies 2 and 3 will be described.

When a high-frequency magnetic field is generated in the induction coil 4 by the high-frequency oscillator, the magnetic body 1 is heated and the tube end faces of the tubes 2 and 3 in contact with the magnetic body 1 are heated and melted. While the end faces of the pipes are being heated and melted (or after being melted by heating), the pipe bodies 2 and 3 are pressed in the directions of the joint surfaces 6 and 7 and butt welded. Then, the high frequency magnetic field is released and the mixture is cooled and solidified. After cooling and solidifying, the induction coil 4 is removed.

Since the magnetic body 1 is disposed in the annular groove 8 provided in the central portion of the tube thickness of each of the tube bodies 2 and 3,
When the magnetic body 1 generates heat, the tubes 2 and 3 are melted from the central portion of the tube thickness to the outer surface and the inner surface. As a result, the fluidity of the resin decreases from the central portion of the pipe thickness to the outer surface and the inner surface, and the beads generated on the inner and outer surfaces during joining of the pipes decrease.

In FIG. 2, reference numeral 5 is an induction coil fixed to the outside of the pipes 2 and 3, and the other components are the same as those in FIG. The pipes 2 and 3 are joined by the same method as in FIG.

FIG. 3 is an explanatory view of various shapes of the induction coil which can be used in the method of the present invention. (A) is a single-turn induction coil 11, (B) is a multi-turn induction coil 12, and (C) is a hairpin-type induction coil 1.
3 and (D) is a pancake type induction coil 13.

[0022]

The high-frequency magnetic field causes the magnetic material to generate heat, which heats and melts the end faces of the pipe body, and the end faces of the heat-melted pipe body are butt welded to each other, so that the heat source and the pipe body come into contact with each other. As a result, problems such as adhesiveness between the heat source and the tube or releasability do not occur.

Therefore, it is not necessary to use a hot plate or the like coated with fluororesin or the like so that the molten resin does not adhere,
Butt welding of heat-resistant thermoplastic resin pipes having a melting temperature higher than that of fluororesins can be easily performed.

Further, since the magnetic body is provided between the pipes, it is hardly affected by the outside air temperature, the pipes can be heated uniformly in the circumferential direction, and the circumferential joining can be made uniform. It can be carried out.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an embodiment of the method of the present invention in which an induction coil is arranged inside a tubular body.

FIG. 2 is a partial cross-sectional view of another embodiment of the method of the present invention in which the induction coil is arranged outside the tubular body.

FIG. 3 is an explanatory view of various shapes of an induction coil that can be used in the method of the present invention.

FIG. 4 is an explanatory diagram of a conventional tube body connecting method.

FIG. 5 is an explanatory diagram of another conventional method of connecting pipes.

[Explanation of symbols]

 1 Magnetic material 2,3 Tubular body 4,5,11,12,13,14 Induction coil 6,7 Bonding surface 8 Groove 9.10 Heat plate

Claims (1)

[Claims] 1. A ring-shaped magnetic body is provided between pipe bodies, an induction coil is arranged outside or inside the pipe bodies, and a high-frequency magnetic field is generated by a high-frequency oscillator to generate heat by the magnetic bodies. A method for joining pipes, characterized in that the end faces of the pipes are heated and melted, or after being heated and melted, the melted portions are butt-welded and then cooled and solidified.