JP3003003B2 - Synthetic resin pipe fittings - 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 synthetic resin joint body and a synthetic resin pipe are fused and joined to each other. The present invention relates to a resin pipe joint.

[Prior Art] Synthetic resin pipes made of olefinic synthetic resins such as polyethylene and polybutene are widely used for gas pipes because of their excellent gas corrosion resistance and the like. On the other hand, since this kind of synthetic resin pipe has poor adhesiveness with an adhesive, a means of fusing a joint surface between a synthetic resin pipe joint and a synthetic resin pipe fitted thereto may be employed for the connection. Many. For the connection by fusion, a method is adopted in which the outer peripheral surface of the synthetic resin pipe and the inner peripheral surface of the synthetic resin pipe joint are heated and softened in advance and then press-fitted to each other.
However, this method has a drawback that in the case of outdoor work, reliable fusion bonding may not be performed depending on weather conditions such as wind and rain and temperature.

Therefore, recently, a synthetic resin pipe joint has been proposed in which a heating wire made of a metal wire that generates heat by energization is spirally wound and embedded in a cylindrical joint body made of a synthetic resin. When the joint body and the synthetic resin tube are fitted together, and the heating wire is energized to generate heat, the heat softens the synthetic resin of the joint body and the synthetic resin tube, and the joint surface of them is melted. Because it is worn, it has the advantage that it is hardly affected by wind and rain and temperature even in outdoor work.

[Problems to be Solved by the Invention] However, in the above-described pipe joint in which a heating wire made of a metal wire is spirally wound and embedded, the restoring force of the metal wire which is going to return to the original shape is a joint. Since it is constantly applied to the body, when the heating of the heating wire softens the joint body, the location where the heating wire is embedded rises and the pipe joint is distorted as a whole. Due to the difference in the linear expansion coefficient between the heating wire and the heating wire, a gap may be formed between the two after the fusion, and the fluid may leak out of the gap. In addition, the heating time of the heating wire often becomes longer than necessary, and in this case, the joint body and the synthetic resin pipe are excessively softened both in a range and a degree, so that the above-mentioned inconvenience is further reduced. It will be noticeable.

As a general measure to solve this problem, a temperature sensor is built in the pipe joint, and when the temperature sensor detects the set temperature, the power to the heating wire is stopped to heat the joint body and the synthetic resin pipe. A method of discontinuing was considered. However, in this method, there is a problem that the total cost increases due to additional equipment such as a temperature sensor.

The present invention has been made in view of the above circumstances, and in causing the heating wire to generate heat and softening the synthetic resin of the joint body, disconnecting the heating wire at a reasonable timing using a change in the state of the synthetic resin. By terminating the heating of the synthetic resin, local swelling and overall distortion of the joint main body and excessive softening of the synthetic resin of the joint main body do not occur. An object of the present invention is to provide a synthetic resin pipe joint in which a gap is not generated between the joint body and the heating wire after fusion with the resin pipe.

Means for Solving the Problems A synthetic resin pipe joint according to the present invention is a linear aggregate of carbon fibers or conductive powder that heats and softens the synthetic resin of the joint body inside the joint body corresponding to the joint surface. And a cavity facing the above-mentioned heating wire is formed at an appropriate position in the joint body, and a portion near the cavity forming portion bulges toward the inside of the cavity as the synthetic resin is heated and softened. A chip that is sometimes pushed toward the heating wire side by the bulging portion and breaks the heating wire is interposed in the cavity.

A through hole is formed in the chip, and a synthetic resin pipe joint in which a heating wire is inserted through the through hole, or a carbon fiber of the heating wire is a long fiber or a short fiber, and the carbon fiber has a linear shape. Synthetic resin pipe joints in which the aggregate is covered with the same synthetic resin as the joint body are also included in the scope of the present invention.

[Operation] In the above-described configuration, when the thin portion is bulged by heating the heating wire to soften the synthetic resin of the joint body, the heating wire is broken by the tip pushed by the bulging portion, and the wire is broken. Thereafter, the heating of the synthetic resin by the heating wire is stopped. When a heating wire is inserted through the through hole of the chip, the heating wire is reliably broken at a certain timing because the heating wire locally follows the chip when the chip is pushed and moved. Is done. In addition, when the carbon fibers of the heating wire are long fibers or short fibers, and the linear aggregate of carbon fibers is covered with a synthetic resin of the same quality as the joint body, handling of the heating wire is easy, and When the wire generates heat, the coating of the synthetic resin is softened and integrated with the joint body, and the heating wire is easily broken with a small force, so that a gap is created between the synthetic resin and the heating wire. Things are less likely to occur.

[Example] FIG. 1 is a perspective view of a synthetic resin pipe joint A according to an embodiment of the present invention, in which a part of the pipe joint A is cut away, FIG. 2 is a cross-sectional view in which main parts are enlarged, and FIG. FIG. 3 is a cross-sectional view showing a connection state with a synthetic resin tube 8.

The joint body 1 of the synthetic resin pipe joint A shown in the figure is made of an olefin-based synthetic resin such as polyethylene or polybutene in a tubular shape, and a heating wire 2 is spirally wound around an inner peripheral portion of the joint body 1 and embedded. Has been entered. The heating wire 2 is formed by covering the linear aggregate 21 of carbon long fibers with the same synthetic resin having compatibility with the synthetic resin of the joint body 1. The coating 22 is adapted to soften.

The heating wire 2 is embedded in the inner peripheral portion of the joint main body 1 by a method described below. That is, the heating wire 2 is spirally wound with almost no gap, and the outer resin portion 1a is formed outside the spiral. According to this method, since the heating wire 2 is easily wound in the shape as designed, the softened state of the synthetic resin of the joint body 1 due to the heat generation of the heating wire 2 can be easily made uniform. There is.

A cavity 3 facing the heating wire 2 is formed at an appropriate position of the joint body 1. Numeral 4 is a chip movably accommodated in the cavity 3, and a flange portion having a diameter slightly smaller than the diameter of the cavity 3.
The heating wire 2 is inserted into a through hole 43 formed in the leg 42 and a leg 42 integrally protruding from the flange 41. The tip 4 is made of a synthetic resin having a softening temperature higher than that of the synthetic resin of the joint body 1 or another material having electrical insulation. When the heating wire 2 is embedded in the joint body 1 by the above-described method, the through-hole of the chip 4 is required in the step of winding the heating wire 2.
The heating wire 2 may be inserted through 43, and the cavity 3 may be formed at the same time when the outer resin portion 1a is formed. In addition, a notched circular portion is formed in the through hole 43 of the chip 4, and the through hole 43 of the chip 4 is later added to the circular hole and the leg 42.
You may make it fit in the heat generating wire 2 using the elasticity of.

In FIG. 1, reference numeral 5 denotes a partition provided in the center of the joint body 1 in an annular shape, which regulates the insertion width of the synthetic resin pipe 8 inserted from the left and right ends.
Is an electrode connected to the heating wire 2 and protrudes outside the joint body 1.

When the end of the synthetic resin pipe 8 is inserted into the pipe joint A having the configuration described above and a voltage is applied to the electrode 6, the heating element 2 generates heat, and the heat softens the coating 22 and the heat is applied to the joint body 1 And the softened portion is transmitted to the synthetic resin tube 8 and the softened portions are integrated by heat fusion. In this process, as the peripheral portion of the cavity 3 of the joint body 1 is softened by heating, the synthetic resin swells to escape into the cavity 3 as shown in FIG. Is pushed and moves inside the cavity 3 as shown in FIG. When the chip 4 moves inside the cavity 3 in this manner, the linear assembly 21 of the heating wires 2 locally follows the chip 4 and when the movement width of the chip 4 becomes large to some extent, the linear assembly 21 Is cut off by the chip 4, the current is stopped, and the heating of the synthetic resin by the linear assembly 21 is automatically stopped. For this reason, when the joint body 1 and the synthetic resin pipe 8 are moderately softened, the heating of the joint body 1 and the synthetic resin pipe 8 is stopped. Gap is less likely to occur. This effect is further promoted by the use of long carbon fibers for the linear aggregate 21. The linear assembly 21 is torn by the chip 4 to be disconnected, or the through-hole of the chip 4
Since the hole 43 is sheared at the hole edge 43a to break the wire, if the hole edge 43a is formed in a sharp shape such as a right angle, the shearing is performed reliably and favorably. Further, when the surrounding synthetic resin is softened by the heat generated by the linear assembly 21, the linear assembly 21 loses a restoring force to return to its original shape, and therefore the joint body 1 locally swells or has an overall distortion. Is unlikely to occur.

In the embodiment described above, the linear aggregate 21 is made of long carbon fibers, but instead of short carbon fibers, carbon black, or a metal powder such as copper powder or aluminum powder. Is also good.

FIGS. 4A and 4B show an example in which the chip 4 is housed in the cylindrical body 43. FIG. The cylindrical body 43 is housed and held in the cavity 3 at an appropriate position of the joint body 1 described above.
You can move within 43. 4A is an explanatory diagram when the heating wire 2 is not generating heat, and FIG. 4B is a diagram illustrating a state in which the heating wire 2 is disconnected due to the movement of the chip 4 in the cylindrical body 43 due to the heating of the heating wire 2. FIG.

FIG. 5 shows a synthetic resin pipe joint A according to another embodiment of the present invention.
6 is a cross-sectional view in which a main part thereof is enlarged, and FIG. 7 is a cross-sectional view taken along line VII-VII of FIG.

The difference between this embodiment and those shown in FIGS. 1 to 3 is that the heating wire 2 is spirally wound and embedded inside the joint body 1 and is formed at an appropriate position in the joint body 1. The point where the thin portion 12 is formed in the joint main body 1 by the hollow 3 is that the tip 4 has a disk shape, and the whole tip 4 is the cavity 3 between the thin portion 12 of the joint main body 1 and the heating wire 2. And the heating wire 2 has no coating.

The method for embedding the heating wire 2 is not particularly limited, but in the illustrated example, the following method is used. That is, the inner layer resin portion 1a corresponding to the inner layer portion of the joint body 1 is first molded,
This is a method in which the heating wire 2 is wound using the spiral groove 11 formed on the outer periphery of the inner resin portion 1b, and then the outer resin portion 1a is formed outside the heating wire 2. According to this method, the heating wire 2
Is easily wound into a shape as designed, so that there is an advantage that the molten state of the synthetic resin of the joint body 1 due to the heat generation of the heating wire 2 can be easily made uniform. In FIG. 6, a boundary line before the outer resin portion 1a and the inner resin portion 1b are fused and integrated is indicated by a virtual line A.

According to this embodiment, the thin portion 12 of the joint body 1 bulges into a state of escaping into the cavity 3 with the heating and softening,
When the chip 4 is pushed from the position indicated by the solid line to the position indicated by the imaginary line C in FIG. Since the heating is not performed, the heating of the synthetic resin by the heating wire 2 is automatically stopped. Other items are the same as those described with reference to FIGS. 1 to 3, and thus the same or corresponding portions are denoted by the same reference characters and will not be described in detail.

[Effects of the Invention] According to the present invention, when the degree of softening of the synthetic resin of the joint body becomes moderate, the heating wire is disconnected and the heating by the heating wire is stopped. Not only is it difficult for a gap to be formed between the resin and the resin, but also a situation in which the synthetic resin is excessively softened is prevented, and local swelling and overall distortion of the joint body are less likely to occur. And since the disconnection of the heating wire is performed not by the bulging portion of the thin portion of the joint body but by the chip pushed by the bulging portion, the heating wire is surely broken at an appropriate timing, and There is an effect that it is easy to set an appropriate timing for disconnection. This effect is more remarkably exhibited by the inventions of claims 2 and 3.

[Brief description of the drawings]

1 is a perspective view of a synthetic resin pipe joint according to an embodiment of the present invention in which a part is cut away, FIG. 2 is an enlarged cross-sectional view of a main part thereof, and FIG. FIG. 4A is an explanatory view showing a state in which a heating wire in another embodiment does not generate heat, and FIG. 4B is a sectional view showing a state in which a chip moves due to heating of the heating wire in another embodiment and the heating wire is disconnected. FIG. 5 is a perspective view in which a part of a synthetic resin pipe joint according to another embodiment of the present invention is cut away, FIG. 6 is a cross-sectional view in which main parts thereof are enlarged, and FIG. FIG. 7 is a sectional view taken along line VII-VII of FIG. 6. A ... synthetic resin pipe joint, 1 ... joint body, 2 ... heating wire, 3 ... cavity, 4 ... chip, 8 ... synthetic resin pipe, 12
... Thin section of the joint body, 12a ... bulge, 43 ... Tip through hole.

Claims (3)

(57) [Claims] 1. A synthetic resin pipe joint in which a synthetic resin joint body and a synthetic resin pipe to be connected to the joint body are fused and joined to each other, wherein a joint is provided inside a joint body corresponding to a joint surface. A heating wire, which is a linear aggregate of carbon fibers or conductive powder for heating and softening the synthetic resin of the main body, is embedded, and a cavity facing the heating wire is formed at an appropriate position in the joint body, and the cavity is formed. When a portion near the point swells toward the inside of the cavity due to the softening of the synthetic resin due to heating and softening, a chip that is pushed back toward the heating wire side by the swelling portion and breaks the heating wire is interposed inside the cavity. A synthetic resin pipe joint characterized by being made. 2. The synthetic resin pipe joint according to claim 1, wherein a through hole is formed in the chip, and a heating wire is inserted through the through hole. 3. The synthetic resin according to claim 1, wherein the carbon fiber of the heating wire is a long fiber or a short fiber, and the linear aggregate of the carbon fibers is covered with a synthetic resin of the same quality as the joint body. Pipe fittings.