JPH071074B2 - Pipe fitting - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pipe joint for connecting pipes made of a thermoplastic synthetic resin, and in particular, a heating wire is spirally formed on an inner peripheral surface of a pipe receiving port. The present invention relates to an improvement of the electric fusion-bonding type pipe joint provided in the.

(Prior Art) For the piping of thermoplastic synthetic resin such as polyethylene pipe, as shown in JP-B-60-23596 and JP-A-58-131025, the inner circumference of the pipe socket of the pipe joint is The heating wire is spirally provided along the surface, both ends are connected and buried in the connector connection terminal, and the heating wire is heated by electricity while the tube is inserted in this tube receiving port. The outer peripheral surface of the inserted tube is melted and the tube is fused inside the tube receiving port.

(Problems to be Solved by the Invention) In the above conventional electric heating fusion-bonding type pipe joint, the heating wire is embedded in the thermoplastic synthetic resin, and the heating wire is energized at the time of fusion with the pipe. , Melt the resin around it,
The heating wire expands when heated and contracts when cooled, so that a void is formed between the heating wire and the surrounding resin. Further, since the resin does not easily adhere to the heating wire, it serves as a passage for the pressurized liquid even in the contact state. Furthermore, since the heating wire is embedded in the inner surface of the pipe receiving hole in a spiral shape with a certain depth, the heating wire remains aligned on the cylindrical surface that is the fusion interface even after fusion with the pipe. . Therefore, after the fusion of the pipe joint and the pipe, when bending stress acts on this joint portion, cracks occur at the fusion interface, that is, at the surface where the heating wires are lined up, and the tip of the pipe (the pipe receiving port Liquids such as water and chemicals and gases such as city gas that flow through the pipe from the inner part) through the gap around the heating wire to the part of the connector connection terminal and the end of the pipe receiving port may leak.

(Means for Solving the Problems) This invention was made in order to solve the drawbacks of the above-mentioned conventional electric heating fusion-bonding type pipe joint, and the first invention is that the heating wire provided in the pipe joint has a fusing part. It is characterized by being provided. This fusing part is designed to normally energize when heating and heating the heating wire, but to fuse when an excessive current flows.Even if the heating wire is thin in part, It may be one that is connected.

Furthermore, in the second invention, the heating wire is provided with a fusing part, and the heating wire spirally wound is provided on the inner peripheral surface of the pipe receptacle in a twisted state so as to reduce the diameter. It is a feature.

(Operation) In using the pipe joint of the present invention, the pipe body is inserted and fitted and held in the pipe receiving port, and a predetermined current is passed between the terminals to heat the heating wire. Due to the heating of the heating wire, the inner peripheral surface of the pipe receiving port and the outer peripheral surface of the tubular body are melted and integrally fused. The heating wire is normally energized when energized and heated, but it has a fusing part that melts when an excessive current is applied.Therefore, energize the heating wire for a sufficient time to melt and weld the pipe socket The fusing part is blown by controlling the current so that an excessive current flows in the heating wire.

When a part of the heating wire is blown, the molten resin flows at the fusing position to close the void. Thereby, the gap generated along the heating wire is blocked, and the leakage generated along the heating wire can be prevented.

Further, in the case where the heating wire spirally wound with the fusing part is embedded in a state of being twisted so as to reduce its diameter, it is given to the heating wire by fusing the fusing part. Since the twist is released, the molten resin is restored and moved so as to have a large diameter. Due to the movement of the heating wire, the heating wire does not exist at the fusion interface between the tube receiving port and the tubular body, and the molten resins of both sides are fused together, so that a strong joint can be made.

(Example) Next, the pipe joint of this invention is demonstrated with reference to drawings.

FIG. 1 is a sectional view showing an example of the pipe joint of the present invention.
Is a pipe joint body, 2 is a heating wire, and 3 is a pipe body to be connected.
Pipe receiving ports 11 and 11 are provided on both sides of the pipe joint body 1, and projections 12 that regulate the insertion depth of the pipe body are provided on the inner side. The heating wire 2 is provided in a spiral shape along the inner surfaces of both tube receiving ports 11, 11 and both ends are terminals 2 provided outside the main body 1.
It is connected to 1,21.

It suffices that the heating wire 2 is provided along the inner surface of the pipe receiving port 11. Even if the heating wire coated with the thermoplastic synthetic resin is arranged in a spiral shape, Even if it is slightly buried, a groove may be provided in the inner peripheral surface of the pipe receiving port 11 and the groove may be arranged in this groove. When the heating wire 2 is covered or buried, the thickness of the resin layer from the inner surface of the pipe receiving port to the heating wire is 0.5 mm or less.
When the thickness is made thicker than this, when the heating wire is energized and the inner surface of the pipe receiving port and the outer surface of the inserted pipe are melt-bonded, the outer surface of the pipe is not sufficiently melted and the fusion is insufficient. This is because.

And in this invention, the fusing part 22 is provided in at least one place of the said heating wire 2. The fusing part 22 may be provided anywhere, but is preferably provided on the spiral winding portion located on the opening side or the inner side of the pipe receiving port 11. Further, as shown in FIG. 1, in a case where continuous heating wires 2 are provided in both tube receiving ports 11 and 11 and the tube bodies inserted in both tube receiving ports are simultaneously fused, It suffices to provide a fusing part in the middle of both pipe receiving ports.

The fusing part 22 can pass an electric current for conducting and heating the heating wire 2 without abnormality, but it is sufficient if the fusing part 22 blows when an electric current larger than this electric current, for example, 1.5 times or more of the electric heating current flows. Even if a part of the heating wire 2 is partially thinned, for example, a notch-shaped notch portion such that a part of the heating wire 2 has a diameter of 0.2 mm or less is provided, the heating wire 2 is cut, and the heating wire 2 has a predetermined excessive size. It may be connected by a fuse that is blown by an electric current.

Further, in the second invention, the spirally wound heating wire is twisted so as to reduce its diameter, and the pipe socket 11
Is provided on the inner peripheral surface of the. For example, heating wire 11
A spiral coil having a diameter of several mm or more larger than that of the spiral heating wire 2 provided in the coil is formed, and the coil is twisted so that the coil has a predetermined small diameter.
It is fixed to the inner surface of 11.

Then, in connection with the pipe body 3, as shown in FIG. 2, the pipe body 3 is inserted and fitted into the pipe receiving ports 11 and 11, and a predetermined current is applied between both terminals 21 and 21 for a predetermined time. Then, the molten resin layer 13 on the pipe port side
And the molten resin layer 31 on the tube side are fused at the fusion interface 14.
When an excessive current is momentarily passed after a predetermined time, the fusing part 22 melts and the heating wire 2 is de-energized. The surrounding molten resin flows into the melted and cut portion and closes the portion.

In the second invention, as shown in FIG. 3, the melting of the heating wire 2 releases the twist applied to the heating wire 2, so that the spiral diameter of the heating wire 2 is restored to be large. Moving. Due to the movement of the heating wire 2, the heating wire 2 moves so as to have a large diameter within the molten resin layer 13 on the inner peripheral surface of the pipe receiving port 11. Therefore, the molten resin layer 13 on the pipe receiving port 11 side and the tube body 3 are moved. The molten resin layer 31 on the side can be fused to the fusion interface 14 without interposing the heating wire 2 therebetween. Further, due to the restoration movement of the heating wire, the space between the both ends 23, 23 of the heating wire of the fusing part is greatly expanded, and the closed portion is lengthened.

FIG. 4 is a sectional view showing another example of the present invention. In this example, separate heating wires 2 and 2 are provided in both tube receiving ports 11 and 11, and both ends of each heating wire are connected in parallel to two terminals 21 and 21. In addition, the fusing part 2
2,22 are formed. The heating wires 2, 2 are provided on the inner peripheral surfaces of the pipe receiving ports 11, 11 in a state in which the heating wires spirally wound are twisted so as to reduce the diameter. In this example, there is a separate heating wire for each
Since the fusing parts 22 are provided, the fusing part 22 can be provided at the optimum position, and the heating wire 2 can be restored and moved more reliably after the breaking.

In addition, in this example, when the pipe body 3 is used so as to be separately connected to the respective pipe receiving ports 11, 11, it is assumed that each end of the heating wire 2, 2 is connected to a separate terminal. Good.

Further, although the socket is described in the above example, an elbow, cheese, reducer or the like may be used. Further, the pipe receiving port according to the present invention may be formed at one or both ends of the pipe body.

Further, in the present invention, by selecting the shape, size, and material of the fusing part, it is possible to fuse the heating wire by energizing the heating wire for a time required for fusing.

(Effects of the Invention) Since the pipe joint of the present invention is configured as described above and the heating wire is provided with the fusing part, the pipe body is inserted and fitted, and the pipe receiving port inner peripheral surface and the pipe body outer surface are sufficiently formed. When an excessive current is supplied after energization and heating for a period of melting, the heating wire is melted at the melting portion.
When the heating wire melts, the molten resin around it flows to the melted portion and closes the gap, so that the gap generated along the heating wire is blocked, and the leakage generated along the heating wire can be prevented.

Further, in the case where the heating wire spirally wound with the fusing part is embedded in a state of being twisted so as to reduce its diameter, it is given to the heating wire by fusing the fusing part. The twisting is released, and the heating wire is restored and moved so that the diameter of the helix becomes large in the molten resin, and this movement causes the gap between the molten resin layer on the inner peripheral surface side of the pipe receiving port and the molten resin layer on the outer surface side of the pipe body. The fusion wire can be fused without intervening the heating wire at the fusion interface, and strong joining can be performed, and the fusing ends of the heating wire spread at the fusing portion to reliably block the gap along the heating wire.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the present invention, FIG. 2 is a front view showing an example of an embodiment of the present invention in a partial cross section, and FIG. 3 is a front view showing another embodiment in a partial cross section, FIG. 4 is a sectional view showing another example of the present invention. 1 ... Pipe joint body, 11 ... Pipe receiving port, 13 ... Molten resin layer on pipe receiving side, 2 ... Heating wire, 21 ... Terminal, 22 ... Fusing part,
3 ... Tube, 31 ... Molten resin layer on the tube side.

Claims (2)

[Claims] 1. An electric heating fusion-bonding type pipe joint in which a heating wire is provided in a spiral shape on the inner peripheral surface of a pipe receiving port made of a thermoplastic synthetic resin, and a fusing portion is provided in the heating wire. Pipe fittings characterized by. 2. An electric heating fusion-bonding pipe joint in which a heating wire is spirally provided on an inner peripheral surface of a pipe receiving port made of a thermoplastic synthetic resin, and the heating wire is provided with a fusing part and a spiral shape. A pipe joint characterized in that the heating wire wound around the pipe is provided on the inner peripheral surface of the pipe receiving port in a state of being twisted so as to reduce its diameter.