JP2736804B2 - Manufacturing method of synthetic resin pipe joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used, for example, as a gas pipe joint, in which a joint body made of a synthetic resin and a synthetic resin pipe to be connected to the joint body are fused to each other. The present invention relates to a method for manufacturing a synthetic resin pipe joint to be joined.

[Prior art] Gas pipes are made of polyethylene with excellent gas corrosion resistance, etc.
Although it is often formed of an olefin-based synthetic resin such as polybutene, it is difficult to bond such an olefin-based synthetic resin with an adhesive. For this reason, such a connection of the synthetic resin pipe generally employs means for fusing the joint surface between the synthetic resin pipe and the pipe joint body.

Conventionally, such fusion as described above heats in advance the outer peripheral surface of the insertion portion of the synthetic resin pipe into the pipe joint body and the corresponding inner peripheral surface of the pipe joint body to a temperature at which these can be fused. At that point, the process was performed by press-fitting a synthetic resin pipe into the pipe joint body. However, in this way,
When the work place is outdoors, reliable fusion may not be performed depending on weather conditions such as rain, wind, or temperature, and a large and expensive fusion machine must be used, resulting in high cost. There was a problem of sticking.

For this reason, a synthetic resin pipe joint has recently been proposed in which a spirally wound metal wire is embedded in a synthetic resin. This synthetic resin pipe joint generates heat by energizing the metal wire with the synthetic resin pipe inserted,
The above-mentioned fusion is performed by melting the joint surface with the synthetic resin pipe.

[Problems to be Solved by the Invention] However, in a synthetic resin pipe joint in which a metal wire spirally formed as described above is installed, the internal portion of the metal wire rises during heat generation due to the restoring force of the metal wire, or the entire pipe joint is raised. There is a problem that distortion may occur, which hinders accurate joining. Further, since the coefficient of linear expansion between the synthetic resin and the metal wire constituting the joint body of the pipe joint is different, a gap may be generated between the metal wire and the joint body after the fusion is completed. The fluid may leak out.

Furthermore, when the interior metal wire is heated to melt the joint surface, if the heat generation time is excessively long, heat is transmitted to portions other than the necessary portions, and there is a possibility that the trouble for the above-described joining may be further increased. As a general method for solving this problem, a method has been considered in which a temperature sensor is built in the pipe joint, and when the temperature sensor detects a set temperature, the power supply to the metal wire is stopped. However, such a method has a problem in that the apparatus is expensive and the overall cost increases due to the auxiliary equipment.

The present invention has been made in view of the above-described circumstances, and has a problem in that a gap is formed between a joint body and a heating element disposed inside the joint body, or distortion is generated in an inner peripheral portion of the heating element. It is another object of the present invention to provide a method of manufacturing a synthetic resin pipe joint that can easily embed a heating element in a form that can reliably and accurately join the joint body and the resin pipe into the joint body.

[Means for Solving the Problems] In order to achieve the above object, a method for manufacturing a synthetic resin pipe joint according to the present invention comprises fusing a synthetic resin joint body to a synthetic resin pipe to be connected thereto. A method for manufacturing a synthetic resin pipe joint, in which carbon fibers are stuck on a synthetic resin film, and then the synthetic resin film is formed into a cylindrical shape to form a heating element constituent part. Then, the synthetic resin film of the cylindrical heating element constituting portion is integrated as a part of the synthetic resin constituting the joint body and embedded in the joint body.

[Function] According to the present invention, since the heating element disposed inside the joint body is formed by molding a synthetic resin film on which carbon fibers are adhered into a cylindrical shape, the heating element and the joint are formed. The difference in the coefficient of linear expansion from the synthetic resin that constitutes the main body becomes smaller,
After the fusion is completed, there is no gap between the heating element and the joint body that causes fluid leakage. Further, since the carbon fiber and the synthetic resin film constituting the heating element are weak against shearing force, the synthetic resin portion inside the arrangement portion of the heating element expands due to the heat generated when the heating element is energized. Displaced to the heating element side, the heating element is electrically disconnected by the pressing force due to the displacement, and excessive heating is automatically stopped,
It is possible to prevent thermal deformation of the joint main body such as distortion occurring in the peripheral portion of the heating element interior, whereby the joint main body and the resin tube can be reliably and accurately joined by fusion. In addition, by forming the heating element using a synthetic resin film, it is possible to easily form the carbon fiber, which is a conductive material, into a cylindrical shape. If it is a body, by arranging it in a mold and pouring the synthetic resin constituting the joint body into the mold, it is possible to easily embed the heating element in the joint body, as described above. It is easy to manufacture a synthetic resin pipe joint that exhibits fusion bonding performance.

Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a synthetic resin pipe joint manufactured by the manufacturing method according to the present invention. The joint body 1 of the synthetic resin pipe joint shown in FIG. 1 is made of an olefin-based synthetic resin such as polyethylene and polybutene.
As shown in FIG. 2, each of which is formed separately by joining together a cylindrical joint outer part 1a and a joint inner part 1b, and these cylindrical joint outer part 1a and joint inner part 1b are formed. A heating element 2 formed in a cylindrical shape as shown in FIG. Further, the joint outer portion 1a
As shown in FIG. 4A, an annular recess 4 extending in the circumferential direction is formed at an intermediate portion in the axial direction, and the bottom of the recess 4 is formed on the inner peripheral side of the heating element 2 due to the presence of the recess 4. An annular thin portion 5 serving as an outer peripheral surface is formed. further,
Electrodes 6, 7 exposed to the outside of the joint body 1 are connected to both ends of the cylindrical heating element 2 embedded in the joint body 1, respectively.

The heating element 2 is formed by arranging a large number of carbon fiber groups 2a in parallel on a synthetic resin film (not shown) made of the same material as that of the joint body 1 or a thermosetting resin such as epoxy resin. Then, the synthetic resin film is formed into a cylindrical shape such that the carbon fiber groups 2a are parallel to the axial direction, thereby forming a heating element constituting portion 2A as shown in FIG. Metal-deposited portions 2b, 2b connected to the electrodes 6, 7 are formed in a band shape at both axial ends of the heating element constituting portion 2A.

Then, in a state where the cylindrical heating element constituting section 2A is arranged in a mold (not shown), the synthetic resin forming the joint body 1 is poured into the mold, whereby the synthetic resin film is connected to the joint body. The synthetic resin pipe joint in which the cylindrical heating element 2 is embedded in the joint main body 1 is manufactured as a part of the synthetic resin constituting the synthetic resin 1.

With the synthetic resin pipe A inserted into the joint body 1 of the synthetic resin pipe joint manufactured as described above, the two electrodes 6, 7
A voltage is applied to the heating element 2 to energize it, and the heating element 2 generates heat, so that the joint surface between the joint body 1 and the synthetic resin pipe A is fused. At the time of such fusion, as shown in FIG. 4B, the synthetic resin material of the deformed and expanded annular thin portion 5 mainly escapes to the concave portion 4 side and presses the heating element 2 from the inside in the entire circumferential direction. . Then, when the pressing proceeds further with the elapse of the heating time, as shown in FIG. 4C, the heating element 2 is electrically disconnected by the synthetic resin material that has escaped to the concave portion 4, and the joint body 1 is thermally deformed by overheating. The heat is automatically turned off before the

FIG. 5 shows a cylindrical heating element constituting part of the synthetic resin pipe joint shown in FIG. 2 which is a cylindrical heating element 2 buried in the joint body 1 and which is substituted for the heating element constituting part 2A of FIG. 2A ', the heating element constituting portion 2' is formed by sticking a woven fabric of carbon fiber on a synthetic resin film and then molding the synthetic resin film into a cylindrical shape. The heating element constituting section 2A 'is also embedded in the joint main body 1 through the same process as that of the heating element constituting section 2 described above. In the case of using the heating element 2 made of such a woven fabric of carbon fibers, since the carbon fibers cross each other, it is not necessary to provide an electrode formed of a metal deposition portion particularly at both ends in the axial direction.
By applying a voltage to both ends of the heating element 2, it is possible to uniformly generate heat as a whole.

In the above-mentioned synthetic resin pipe joint, since the heating elements 2 embedded in the joint body 1 are both made of carbon fiber and a synthetic resin film, the difference in the linear expansion coefficient between the heating element 2 and the joint body 1 is small. When both are fused together for bonding with the synthetic resin tube A, there is almost no distortion in the periphery of the heating element interior, and there is almost no gap between the first and second parts after fusion.

The material of the joint body 1 of the synthetic resin pipe joint may not be an olefin-based synthetic resin, but may be another thermoplastic synthetic resin.

[Effects of the Invention] As described above, according to the present invention, since a heating element formed by molding a synthetic resin film having carbon fibers adhered therein into a cylindrical shape is embedded in the joint body, a synthetic resin pipe is provided. The difference in the degree of expansion between the heating element and the synthetic resin forming the joint body during fusion bonding of the joint body is reduced, so that a gap that causes fluid leakage does not occur between the two after completion of fusion. Also,
Since the carbon fiber and the synthetic resin film constituting the heating element are both weak to shearing force, when the heating element is energized and heat is generated, the heat is applied to the heating element side due to the expansion of the synthetic resin portion inside the arrangement portion of the heating element. Excessive heat generation is automatically stopped by electrically disconnecting the heating element by the pressing force due to the displacement, thereby preventing thermal deformation of the joint body such as distortion occurring around the heating element interior. As a result, the resin tube of the joint body can be reliably and accurately joined by fusion. In addition, by using a synthetic resin film and carbon fibers as components of the heating element, it is possible to easily form the carbon fiber, which is a conductive material, into a cylindrical shape, and the heating element formed into such a cylindrical shape. Can be easily embedded in the joint body by a simple method such as placing it in a mold and pouring the synthetic resin constituting the joint body into the mold,
Therefore, there is an effect that a synthetic resin pipe joint having excellent fusion bonding performance as described above can be easily manufactured and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a synthetic resin pipe joint manufactured by the manufacturing method according to the present invention, FIG. 2 is a longitudinal sectional view of the synthetic resin pipe joint of FIG. 1, and FIG. 4A to 4C are perspective views of a heating element embedded in a synthetic resin pipe joint shown in FIGS. 4A to 4C. FIG. 4A to FIG. 4C are main parts for explaining a disconnection process of the heating element during fusion bonding with a synthetic resin pipe due to heat generation of the heating element. FIG. 5 is an enlarged vertical sectional view, and FIG. 5 is a perspective view showing a modification of the heating element. 1 Joint body 2 Cylindrical heating element 2A, 2A 'Heating element component 2a Carbon fiber

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Claims (1)

(57) [Claims] 1. A method of manufacturing a synthetic resin pipe joint in which a synthetic resin joint body and a synthetic resin pipe to be connected thereto are fused and joined to each other. A carbon fiber is adhered, and then the synthetic resin film is formed into a cylindrical shape to form a heating element constituting part. The synthetic resin film of the cylindrical heating element constituting part is part of the synthetic resin constituting the joint body. A method of manufacturing a synthetic resin pipe joint, wherein the pipe is integrated and embedded in a joint body.