JPH0932981A - Pipe joining method and joint therefor - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a pipe joining method in which joints can be evenly bonded and which is less likely to be damaged, and a joint therefor. SOLUTION: In a method of setting pipes 1 and 2 to be joined to a tubular joint 3 and emitting high frequency to the joints to join the pipes 1 and 2 through the joint 3 by high frequency heating, the joint 3 and the pipes are joined together. A tape 4 in which fibers or particles of a substance that generates heat in a high-frequency magnetic field is kneaded with a resin is arranged between the joint surfaces 1 and 2, or heat is generated in the high-frequency magnetic field on the pipe joint surface side as a joint. A joint having a resin layer in which fibers or particles of the substance to be mixed are kneaded is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joining method and a joint therefor.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride pipes have been commonly used for water pipes and gas pipes. However, it is considered that pipes made of polyethylene, polypropylene, etc., which are more flexible than vinyl chloride and less likely to be broken or damaged, will rapidly increase in the future, for example, in response to earthquakes.

However, polyethylene or the like has a property that it is difficult to bond with an adhesive. Therefore, as a method of joining pipes made of such materials, a method of bonding by utilizing high frequency induction heating is known. That is, a tubular joint is used, a pipe is inserted into the joint, and a heater material that is easily induction-heated by a high frequency is arranged between the facing surfaces, and a high frequency is emitted to heat-weld the same. Is a method of joining pipes through a joint.

As a typical method, a method using a mesh-shaped heater material is known from Japanese Patent Laid-Open No. 6-278211.

[0005]

However, in the above method, the joint portion of the pipe which is not in contact with the mesh portion may not be sufficiently adhered. Further, there is a fear that the pipe is damaged such that only the pipe portion in contact with the mesh portion is excessively heated and carbonized.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for joining pipes in which the joints can be evenly bonded and the pipes are less likely to be damaged, and a joint therefor. To do.

[0007]

According to a first aspect of the present invention, there is provided a method for setting a pipe to be joined to a tubular joint, and emitting a high frequency to the pipe to join the pipe through the joint by high frequency induction heating. A resin layer in which fibers or particles of a substance (typically a metal) that generates heat in a high frequency magnetic field is kneaded with a resin is arranged between the joint surfaces of the joint and the pipe. This resin layer may be provided in any manner. For example, the resin layer is formed in a sheet shape or the like in advance, and is arranged between the joint surfaces of the joint and the pipe.
In other words, after the morphology of the resin layer is formed, the arrangement is performed. Alternatively, the arrangement of the resin layer and the morphological formation thereof may be performed at the same time, such as by spray coating.

The first invention is typically a method of setting a pipe to be joined to a tubular joint, and emitting a high frequency to the pipe to join the pipe through the joint by high frequency induction heating. It is characterized in that a sheet in which a material fiber or particles that generate heat in a high frequency magnetic field is kneaded with a resin is arranged between the joint surfaces of the pipes.

In the present invention, since the resin layer such as the tape can be uniformly provided on the entire joint surface of the joint and the pipe, a uniform adhesion is completed at the joint portion of the joint and the pipe.

A second aspect of the present invention is a method of setting a pipe to be joined in a tubular joint, and emitting high frequency to the pipe to join the pipe through the joint by high frequency induction heating. A joint having a resin layer in which fibers or particles of a substance that generates heat in a high-frequency magnetic field is kneaded is used on the joint surface side.

In this method, the fibers or particles of the substance that generate heat in the high-frequency magnetic field generate heat, and the resin layer containing the heat is melted accordingly, and uniform bonding is completed at the joint between the joint and the pipe. .

The present invention also provides a tubular joint having a resin layer, on the pipe joint surface side, in which fibers or particles of a substance that generates heat in a high frequency magnetic field are kneaded.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings while referring to the drawings.

FIG. 1 is a sectional view showing an embodiment of the pipe joining method of the first invention. As shown in the drawing, the pipes 1 and 2 to be joined are inserted from the respective openings of the tubular joint 3. The inner surface of the joint 3 has a very gentle taper shape so that the diameter becomes smaller toward the central portion. This makes it easier to insert the pipes 1 and 2 into the joint 3. In addition, a ring-shaped protrusion 3A is provided at the center of the inside of the joint 3 so as to extend over the inner circumference. To this, the pipes 1, 2 can be positioned most efficiently for joining with the abutment joint 3.

The inner surface of the joint 3, that is, the pipe 1,
A tape 4 prepared by kneading a metal fiber, which generates heat in a high frequency magnetic field, with a resin is arranged between the two bonding surfaces. That is, two tapes 4 each having a width of about half the length of the joint 3 and a length substantially equal to the outer peripheral length of the pipes 1 and 2 are wound in a cylindrical shape and inserted from the respective openings of the joint 3, It is arranged so as to cover its inner surface (excluding the portion of the protrusion 3A).

The length and width of the tape and the arrangement of the tape on the inner surface of the joint 3 can be freely selected, and the joint surface of the inner surface of the joint 3 with the pipes 1 and 2 (preferably the tape) can be selected by one or more tapes. It is enough to be able to cover the whole).

The resin, which is one of the materials for the tape 4, is
Any material that contributes to the adhesion between the pipes 1 and 2 and the joint 3 when heat is applied, or any kind that does not interfere with the adhesion may be used, but the pipes 1 and 2 or the joint 3 may be used. The same material as is preferable.

The metal fibers kneaded in the tape 4 are various ferromagnetic metals (for example, Fe, which generate heat in a high frequency magnetic field).
Fe-Ni, Ni and their alloys).

The thickness of the tape 4 is usually 0.2 to 1.0 m.
m, preferably 0.3 to 0.5 mm.

The metal fibers are usually contained in the tape in an amount of 30 to 30.
80% by weight, preferably 40-60% by weight. The metal fibers are preferably kneaded so that they are dispersed in the resin as homogeneously as possible.

The metal fibers are needle-shaped and the thicker they are, the higher the heat efficiency is. However, from the viewpoint of the workability of the tape (to avoid the difficulty of cutting, to prevent the fibers from being conspicuously exposed, etc.), it is usually 100 μm. Below, preferably 30 to 90 μm
It is. The length of the metal fiber is usually 3 mm or less, preferably 2 mm or less, from the viewpoint of tape processability and feedability to the molding machine.

The joined body of the pipes 1 and 2 and the cylindrical joint 3 as described above is set in the high frequency generator 5 including the work coil 5A and the high frequency oscillator 5B.

In this state, when a high frequency magnetic field is generated by the high frequency oscillator 5B via the work coil 5A, an eddy current is generated in the metal fiber by electromagnetic induction and heating is started. Immediately after heating, the pipes 1 and 2 should be
Insert it all the way so that it hits A. This operation is performed by pressing the pipes 1 and 2 immediately after the tape 4 is melted so that the melted tape 4 is melted into the pipes 1 and 2 and the joint 3
The reason is that the pipes 1 and 2 can be fitted to the adhered part and a strong joint can be obtained, but the pipes 1 and 2 may be inserted from the beginning to the back.

When the heating is continued, the pipes 1 and 2 and the joint 3 are joined to each other via the heat-welded tape.

In this embodiment, since the metal fibers to be heated are dispersed in the entire joint between the pipes 1 and 2 and the joint 3, the heating can be carried out uniformly. Therefore, the bonding can be performed uniformly over the entire joint portion. Moreover, a part of the pipes 1 and 2 is not damaged.

The tape 4 may be set on the pipes 1 and 2 in advance, and the pipes 1 and 2 may be inserted into the joint 4.

An embodiment of the pipe joining method of the second invention will be described. In that form, a joint 6 as shown in FIG. 2 is used. That is, the core layer 6A on the inner surface side,
The joint 6 which is a two-layer structure with the outer layer 6B on the outer surface side is used. The core layer 6A is made of a material obtained by kneading a metal fiber with a resin. On the other hand, the outer layer 6B is made of resin. Although not essential to the present invention, the inner side of the joint 6 may be tapered or a protrusion may be provided at the center of the joint 6, as shown in FIG. 1.

The resin of the core layer 6A and the metal to be kneaded are
The same tape as that used for the tape 4 can be used.

Since the core layer 6A is for adhesion by high frequency induction heating, its thickness can be selected from any range as long as it fulfills its function. The ratio of the thickness to the joint thickness is also the same. The thickness of the core layer 6A is, for example, 0.5 to 1.0 mm.

The joint 6 may be manufactured by any method, but for example, simultaneous extrusion molding of two layers and two layer molding by injection can be preferably used.

In the same manner as described with reference to FIG. 1, the joint 6 can be used to join the pipes by using high frequency induction heating.

In this embodiment, the pipe and the joint 6
Since the metal fibers are dispersed in the entire core layer 6A corresponding to the portion facing with, heating can be performed uniformly.

This embodiment is also particularly effective for joining pipes made of polyethylene, polypropylene, etc., which are difficult to bond with an adhesive as in the above embodiment. However, it is also possible to apply an adhesive agent which exhibits adhesiveness by heat between the pipe and the joint 6. This is particularly effective for joining resin pipes that are easily bonded by an adhesive. In this case, since the resin material of the core layer does not need to consider adhesiveness to the pipe, there is an advantage that the material can be selected from a wide range.

As a joint, a semi-cylindrical molded product 7 obtained by dividing a cylinder into two as shown in FIG. 3 is used.
The two may be used in combination as shown in FIG. This molded product 7
Also has a core layer 7A and an outer layer 7B, and a layer similar to the core layer 7A is provided on the surface where the molded products 7 are joined together. With this layer, the molded products 7A can be heated and welded to each other at a high frequency at the same time when the joint and the pipe are joined. This aspect has the advantage that the joining operation is easy to carry out.

The first and second aspects of the present invention are not limited to the above-described modes, but can take various modes.

For example, instead of metal fibers, metal particles can be used. In this case, the particle size is usually 50 to 300 μm.
m, preferably 100 to 200 μm.

Further, the joint may be three-pronged or the like. Further, the inner peripheral surface of the pipe may be fitted to the outer peripheral surface of the joint. In that case, in the case where the joint has a multi-layered structure, the outermost layer may be a resin layer in which metal fibers or the like are kneaded.

[0038]

【Example】

Example 1 40% by weight of linear low-density polyethylene has an average diameter of 50 μm.
60% by weight of iron needle filler of m is premixed with a tumbler, extruded and granulated, and then a T-die molding is performed with a single-screw extruder to form a sheet with a thickness of 0.5 mm. It was cut into 24 mm to obtain a tape for high frequency induction heating adhesion. The pipe, the joint and the high frequency induction device shown in FIG. 1 were prepared, and the tape was cut to obtain two tapes having a length substantially equal to the outer peripheral length of the pipe. They were formed into a cylindrical shape, inserted through each opening of the joint, and set on the inner surface of the joint.

The outer diameter of the pipe is 33 mm, the inner diameter of both ends of the joint is 34.4 mm, and the inner diameter of the central portion beside the protrusion is 34 mm.

Pipes were inserted from both ends of the joint, set in a work coil, and heated for 15 seconds by a high frequency oscillator having an oscillation frequency of 400 KHz and an output of 1 KW. Immediately after heating, the pipe was pushed inside the joint so that it hits the protrusion in the center. Bonding was completed in a cooling time of about 30 seconds. Example 2 40 wt% of high-density polyethylene and 60 wt% of iron-nickel alloy needle filler having an average diameter of 60 μm were pelletized in the same manner as in Example 1, and this and high-density polyethylene were used as raw materials for uniaxial An inner core layer for high-frequency induction heating adhesion made of pellets and an outer layer made of polyethylene as a raw material were simultaneously extruded by an extruder to form the joint shown in FIG. The joint inner diameter was 33.5 mm. Two pipes having an outer diameter of 33 mm were inserted into this joint from both ends, and the same work coil as that used in Example 1 was set. A high-frequency oscillator having an oscillation frequency of 400 KHz and an output of 1 KW was used for heating time of 15 seconds and cooling time of 30 seconds. Joined in seconds. Example 3 Using the pellets produced in Example 2, as shown in FIG. 3, it is a semi-cylindrical shape obtained by dividing a cylinder into two, a core layer for high-frequency induction heating bonding having a thickness of 1 mm, and a high density on the outside. Two molded articles having a two-layer structure having a polyethylene layer were obtained by two-layer injection molding. These are piled up as shown in Fig. 4 to form a joint, a pipe is inserted inside, set in the work coil, and joined with a high-frequency oscillator with an oscillation frequency of 400 KHz and an output of 1 KW in a heating time of 20 seconds and a cooling time of 40 seconds. I went.

In all of Examples 1 to 3, strong and practical pipe joining was achieved.

[0042]

According to the present invention, the joint surfaces of the pipes can be evenly bonded and the pipes can be joined with high reliability. Moreover, the joint surface of the pipe is not damaged by the joint. The present invention is particularly suitable for the use of pipes such as polyethylene and polypropylene whose use is expected to increase rapidly in the future.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pipe joining method of the present invention.

FIG. 2 is an external view showing an example of a joint that can be used in the method of the present invention.

FIG. 3 is an external view showing a semi-cylindrical molded product that constitutes a joint that can be used in the method of the present invention.

FIG. 4 is an end view in which a joint is formed by combining two of the above semi-cylindrical molded products.

[Explanation of symbols]

 1, 2 Pipes 6, 7 Joints 3 Joints 6A, 7A Core layer 4 Tapes 6B, 7B Outer layer 5 High frequency generator

Claims (4)

[Claims] 1. A method of setting a pipe to be joined to a tubular joint, and emitting a high frequency wave to the pipe to join the pipe through the joint by high frequency induction heating. In the method, a high frequency magnetic field is provided between the joint surfaces of the joint and the pipe. A method for joining pipes, characterized in that a resin layer is prepared by kneading fibers or particles of a substance that generates heat therein with a resin. 2. A method in which a pipe to be joined is set in a tubular joint and a high frequency is emitted to the pipe to join the pipe through the joint by high frequency induction heating, in which a high frequency magnetic field is applied between the joint surfaces of the joint and the pipe. A method for joining pipes, characterized in that a tape obtained by kneading fibers or particles of a substance that generates heat therein is mixed with a resin. 3. A method of setting a pipe to be joined to a tubular joint, and emitting a high frequency wave to the pipe to join the pipe through the joint by high frequency induction heating. A method for joining pipes, which comprises using a joint having a resin layer in which fibers or particles of a substance that generates heat in a high frequency magnetic field are kneaded. 4. A tubular joint having a resin layer in which fibers or particles of a substance that generates heat in a high frequency magnetic field are kneaded on the pipe joint surface side.