JPH07117130A - Plastic tube connecting method - Google Patents

Abstract

PURPOSE:To connect a plastic tube and a joint even when the joint does not have a self fusing property, as well as in the case that the joint has the self heat fusing property equipped with a heating wire or a heating element embedded therein. CONSTITUTION:A thermoplastic resin tape 2 in which a ferrite powder is mixed is wound on a tube end of a plastic tube 1 and inserted into a socket joint 3 from both sides. By using a heating device 4 consisting of a high-frequency generating device, an electrode core and an excitation coil, an alternating field of 1-400kHz is generated so as to heat the ferrite powder in the tape and to fuse it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method for joining plastic pipes using a joint.

[0002]

2. Description of the Related Art Conventionally, the joining of plastic pipes has been accomplished by heating and melting the contact surfaces of the joint and the plastic pipe with a heater, and then inserting the joint into the end of the plastic pipe or pressing it against the outer peripheral surface of the plastic pipe from the side. Although it was performed by heat fusion, in recent years, using an electrofusion joint in which a heating wire is embedded in a coil shape inside the joint body,
A method has been developed in which, after being attached to a plastic pipe, power is supplied to the joint for a set period of time to heat and melt by the heat generated by the heating wire.

As a method of joining a plastic pipe using a self-heat-sealing joint that heat-seals by heat generation, as described in Japanese Patent Laid-Open No. 56-50036, the inner surface of the joint is cut. A conductive material made of a thermoplastic polymer mixed with ferromagnetic metal powder having a Curie point within the melting temperature range of the resin is embedded in the provided annular groove, and a frequency of 10 to 500 KHz is generated by an induced current generator. A method of generating an alternating magnetic field having the above and thereby generating an eddy current in the metal powder to heat the powder, as disclosed in JP-A-1-325261, comparison of induction loss coefficients having an induction loss coefficient of 0.1 or more. Made of a kneaded material of 30 to 60% by weight of high resin and a thermoplastic resin material of the same material as the plastic pipe, and an annular core preformed by injection molding is in contact with the outer peripheral surface of the plastic pipe. Only, a method of heating is heating the core by microwave irradiation is known. Regarding the resin containing a heating element, there is known Japanese Patent Laid-Open No. 3-285924 in which magnetic powder is mixed with resin to generate heat by magnetic hysteresis loss due to an alternating magnetic field applied by a magnetic field generator.

[0004]

According to the method for joining plastic pipes using a self-heat-welding joint, the joint and the plastic pipe are heated and melted by a heater, and then the joint is formed into a plastic pipe. Compared with the method of attaching and heat-sealing, the connection work can be performed easily and quickly, the work efficiency is improved, and the joining can be performed relatively reliably. Special fittings must be used, such as fittings with embedded hot wires or heating elements.

An object of the present invention is to use a thermoplastic joint in which a heating wire or a heating element is not buried, and to join it with a plastic pipe in the same manner as when using a self-heat-welding joint. It is intended to provide a simple joining method.

[0006]

The method for joining plastic pipes according to the present invention is a sheet or a sheet made of a thermoplastic resin mixed with magnetic powder (hereinafter referred to as magnetic powder) composed of magnetic iron oxide powder, ferrite powder or a mixture thereof. Wrap the sheet around the end of the plastic pipe with tape (hereinafter simply referred to as the sheet) and insert it into the joint, or press the seat against the outer peripheral surface of the plastic pipe and press the saddle joint to fix it. After that, an alternating magnetic field of 1 to 400 KHz is generated using a heating device composed of a high frequency generator, an electrode core and an exciting coil, and heat fusion is caused by heat generation of the magnetic powder.

Another joining method is to use a sheet or the like made of a thermoplastic resin mixed with ferromagnetic metal powder having a Curie point within the melting temperature range of the resin, and wind the sheet or the like around the end of the plastic pipe. 10) by using an induced current generator after inserting the sheet into the joint or pressing a sheet etc. to the outer peripheral surface of the plastic pipe and pressing it to the saddle joint to fix it.
It is characterized in that an alternating magnetic field having a frequency of 500 KHz is generated to generate an eddy current in the metal powder to generate heat and thermally fuse.

Yet another method is to construct a sheet or the like from a thermoplastic resin material containing 30 to 60% by weight of a resin having an inductive loss coefficient of 0.1 or more, and irradiate the sheet with microwaves from an induced current generator. It is characterized in that the above materials are heated and heat-sealed.

[0009]

[Function] When an alternating magnetic field is generated using an induction heating device, magnetic powder mixed in a sheet or the like causes magnetic hysteresis loss, or metal powder heats up due to eddy current, and an induction loss occurs when microwave is applied. Resin with a high coefficient generates heat. The magnetic properties of the magnetic powder mixed in the sheet used in the present invention are such that the saturation magnetization Os is 50 emu / g or more, the coercive force Hc is 50 Oe or more, and the mixing ratio with the resin is such that the coercive force Hc of the magnetic powder is In the case of 50-200 Oe,
The magnetic powder is 50 to 90% by weight, preferably 50 to 85% by weight. In this case, when the magnetic powder is less than 50% by weight, it is difficult to obtain a heat generating material having a maximum magnetic flux density Br of 1000 G or more, and the heat generating effect in a short time is low. 90 magnetic powder
When the content exceeds the weight%, it becomes difficult to fill and disperse the magnetic powder in the resin.

When the coercive force Hc of the magnetic powder exceeds 200 Oe, the mixing ratio with the resin is less than 50% by weight of the magnetic powder,
It is preferably 5 to 30% by weight. 50% by weight of magnetic powder
If it exceeds, the heat generation effect is too large, and there is a high possibility that the resin may be deteriorated in some cases. Considering the amount of magnetic powder required to obtain effective heat generation, the lower limit value is 0, 1% by weight.

The shape of the magnetic powder may be cubic, spherical, hexagonal or needle-like. Spherical and cube-shaped ones have an average diameter of 0.1 μm
The above is preferable, and the needle-shaped one has a major axis of 0.1 μm.
As described above, it is desirable that the minor axis is 0.01 μm or more.
Examples of the thermoplastic resin used for the joint and the plastic pipe of the present invention include polyolefins such as polypropylene and polyethylene, polyvinyl chloride, polystyrene, and copolymers thereof. Among them, the number of carbon atoms is 2 to 2.
0 polyolefin, especially ethylene, propylene, butene-1,4-methylpentene-1 having 2 to 12 carbon atoms
Preferred examples include α-olefin homopolymers and copolymers.

The sheet made of resin mixed with magnetic powder is
It has an insulating property, a coercive force Hc of 50 Oe or more, and a maximum magnetic flux density B _M of 1000 G or more, preferably 1200 G or more. When the coercive force Hc is less than 50 Oe, the magnetic hysteresis loss is too small, and when the maximum magnetic flux density B _M of the magnetic powder is less than 1000 G, or the residual magnetic flux density Br / coercive force Hc of the magnetic powder is less than 1.3. In this case, the magnetic hysteresis loss becomes small, and sufficient heat generation may not be obtained. Therefore, when the residual magnetic flux density Br / coercive force Hc has a magnetism of 1.3 or more, good results are often obtained.

The applied alternating magnetic field during fusion is about 1 to 15 times the coercive force of the magnetic material. When the applied alternating magnetic field is less than 1 time the coercive force of the magnetic substance, the heat generation efficiency decreases,
Moreover, even if an alternating magnetic field exceeding 10 times is applied, the heat generation efficiency is not significantly affected. Considering the energy saving of heating and the scale of the heating device, it is about 2 to 10 times, preferably 5 to
About 10 times is desirable.

When a sheet containing a resin having a high induction loss coefficient is used instead of the sheet containing magnetic powder,
As the resin having a high induction loss coefficient, a resin having a melting point of 180 ° C. or higher and an induction loss coefficient of 0.1 or higher is used.
The mixing ratio is 30 to 60% by weight. If it is less than 30% by weight, the heat generated by the induced current is insufficient,
If the content exceeds 50% by weight, the strength after fusion becomes weak. Further, the use of a resin having a melting point of 180 ° C. or higher facilitates the kneading of the resin.

As the resin having an inductive loss coefficient of 0.1 or more, for example, nylon 6 having an inductive loss coefficient of 0.1,
Examples include phenolic resins having an induction loss coefficient of 0.2.

[0016]

1 and 2 show an example of a method for joining a plastic pipe and a socket joint. First, a thermoplastic resin in which ferrite powder is mixed in the end portion of a plastic pipe 1 made of a thermoplastic resin. After winding the tape 2 (FIG. 1), the pipe ends of the plastic pipe 1 on which the tape 2 is wound are inserted into the socket joint 3 from both sides. Then, an alternating magnetic field of 1 to 400 KHz is generated by using the heating device 4 composed of the high frequency generator, the electrode core and the exciting coil, whereby the ferrite powder of the tape 2 is heated and fused.

In FIG. 3, a saddle joint 7 is attached to the outer peripheral surface of a plastic pipe 6 from the side via a thermoplastic resin sheet 8 mixed with ferrite powder, and a tape 2 is wrapped around the pipe end. It shows an example in which the tube 9 is inserted and attached.

[0018]

According to the method for joining plastic pipes of the present invention, even in a joint having no self-heat-sealing property, a tape or the like is wound around the plastic pipe, or an alternating magnetic field is applied by interposing the tape or the like, Alternatively, by irradiating with a microwave, it is possible to join the plastic pipe and the joint in the same manner as when the joint having the self-heat fusion property is used.

[Brief description of drawings]

FIG. 1 is a perspective view of a pipe end portion of a plastic pipe on which a tape is wound.

FIG. 2 is a cross-sectional view showing when a plastic pipe is joined by a socket joint.

FIG. 3 is a sectional view when a saddle joint is used.

[Explanation of symbols]

1, 6, 9 ... Plastic tube 2 ...
Tape 3 ・ ・ ・ Socket joint 4 ・ ・ ・
Heating device 7 ... Saddle joint 8 ...
Sheet

Claims (3)

[Claims] 1. A sheet or tape made of a thermoplastic resin mixed with magnetic powder of magnetic iron oxide powder, ferrite powder, or a mixture thereof is used, and the sheet or the like is wound around the end of the plastic pipe, and the joint is attached to the joint. 1-400K using a heating device consisting of a high frequency generator, an electrode core and an exciting coil after pressing or fixing a saddle joint from the outer surface of the plastic tube
A method for joining plastic pipes, characterized in that an alternating magnetic field of Hz is generated, and heat fusion is caused by heat generation of magnetic powder. 2. A sheet or the like made of a thermoplastic resin mixed with a ferromagnetic metal powder having a Curie point within the melting temperature range of the resin is used, and the sheet or the like is wound around the end portion of the plastic pipe and is attached to the joint. Insert or press a sheet etc. on the outer peripheral surface of the plastic pipe and press it to the saddle joint to fix it, then generate an alternating magnetic field with a frequency of 10 to 500 KHz by the induced current generator to generate an eddy current in the metal powder. A method for joining plastic pipes, which is characterized in that the plastic pipes are caused to generate heat and thermally fused. 3. The sheet or tape is made of a thermoplastic resin material containing 30 to 60% by weight of a resin having an inductive loss coefficient of 0.1 or more, and microwaves are emitted from an induction current generator to heat the sheet or the like. The method for joining plastic pipes according to claim 2, wherein the heat treatment is performed by heat fusion.