JPH10246381A - Electrofusion joint for synthetic resin pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it easily installable, in addition to being lighter in weight as well as to secure the excellent joining strength of pipe ends to each other. SOLUTION: In an electrofusion joint for a synthetic resin pipe, equipped with a joint body 10, of the same material as this synthetic resin pipe, being held between two pipe ends 13A and 13B of both synthetic resin pipes to be butted with each other and an energized heating element 11 embedded in this joint body 10, which is formed into a hollow truncated conical shape, and an inner circumferential surface of the pipe end 13A on one side is made to adhere close to an outer circumferential surface of this joint body 10, which an outer circumferential surface of the pipe end 13B on the other is made to adhere to an inner circumferential surface of the joint body 10, so that they are formed on respective tapered surface shapes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion joint for a synthetic resin pipe, and more particularly to an electric fusion joint which can be easily mounted, lightweight,
The present invention relates to an electric fusion joint for a synthetic resin pipe that can obtain a high joining strength between pipe ends.

[0002]

2. Description of the Related Art Conventionally, there is an electric fusion joint for a synthetic resin pipe as a joint for a polyethylene resin pipe used for a water pipe or the like. As shown in FIG. 2, the electric fusion joint for a synthetic resin pipe has a thick-walled tubular joint body 2 made of polyethylene resin which is attached across both pipe ends 1, and is embedded in the joint body 2. And a heating element 3 made of a coiled nichrome wire. A current flows from the power supply 5 to the energizing heating element 3 via the terminal 4. The current is controlled by the controller 6.

In order to join the pipe ends 1 by the above-mentioned conventional joint, the following is performed. That is, the outer surface of the pipe end 1 is cut to remove a portion degraded by oxidation or the like. Next, the joint main body 2 is mounted over both pipe ends 1. Then, electricity is supplied to the electric heating element 3 to heat and melt the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint body 2. Thus, the two tube ends 1 are fused and joined together.

[0004] As shown in FIG. 3, the joint body 2 is provided with an indicator 7 for managing the molten state of the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint body 2. The indicator 7 is formed of a rod inserted into a through hole 8 formed in the joint body 2. When the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint main body 2 are melted by energization, the interface pressure at the contact portion between the pipe end 1 and the joint main body 2 increases, so that the indicator 7 rises. By monitoring the amount of protrusion, the molten state of the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint body 2 can be managed. When the indicator 7 rises above the surface of the joint body 2 as shown in FIG. 4, it is determined that the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint body 2 have completely melted, and the energization is stopped.

[0005]

However, the above-mentioned conventional electric fusion joint for a synthetic resin pipe has the following problems. Since the inner diameter of the joint body 2 and the outer diameter of the pipe end 1 are substantially equal, it is difficult to mount the fitting on the pipe end 1. In particular, the larger the diameter of the pipe, the more the weight increases, making it difficult to mount. If the fusion area between the outer peripheral surface of the pipe end 1 and the inner peripheral surface of the joint body 2 is not large, the joining strength is low. Therefore, it is necessary to lengthen the joint body 2 to some extent. However, the weight increases as the joint body 2 becomes longer. Since the inner peripheral surface of the joint main body 2 is a parallel cylindrical surface, the abutting portion of the pipe end 1 can be connected to the joint main body 2 without any means such as forming a ring-shaped ridge 9 on the inner peripheral surface of the joint main body 2. 2 cannot be located at the center.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electric fusion splice for a synthetic resin pipe which can be easily mounted, is lightweight, and has a high joining strength between the pipe ends.

[0007]

According to the first aspect of the present invention,
Electric fusion for a synthetic resin pipe, comprising a joint body of the same material as the synthetic resin pipe, sandwiched between pipe ends of the synthetic resin pipe butted against each other, and a current-carrying heating element embedded in the joint body. In the joint, the joint main body is formed in a hollow truncated cone shape, one inner peripheral surface of the pipe end is in close contact with an outer peripheral surface of the joint main body, and the other outer peripheral surface of the pipe end is
The joint body is formed in a tapered shape so as to be in close contact with an inner peripheral surface of the joint body.

According to a second aspect of the present invention, the joint body includes:
It is characterized in that it has a saddle that straddles the outer peripheral surfaces of the two pipe ends and is in close contact therewith. The invention according to claim 3 is characterized in that the electric heating element is made of a nichrome wire or an electric heating fiber.

A fourth aspect of the present invention is characterized in that a stiffener is fitted into the inner peripheral surfaces of the two pipe ends joined via the joint body.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the electric fusion joint for a synthetic resin pipe of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a pipe end joined by an electric fusion joint for a synthetic resin pipe according to the present invention. In FIG. 1, reference numeral 10 denotes a joint main body formed of the same material as a synthetic resin pipe to be joined, which is formed in a hollow truncated cone shape. The joint body 10 does not cover the outer peripheral surface of the pipe end unlike the conventional joint described above, so that the joint body 10 can be thin and light. Moreover, since the joining surface is a tapered surface, the joining area is wider than the parallel cylindrical surface of the conventional joint. Therefore,
The joining strength increases by this amount. Reference numeral 11 denotes an energizing heating element buried in the joint body 10, and an energizing terminal 12
Is provided. The inner peripheral surface of one pipe end 13A is in close contact with the outer peripheral surface of the joint body 10, and the outer peripheral surface of the other tube end 13B is in a tapered surface so as to be in close contact with the inner peripheral surface of the joint body 10. Is formed. The joint body 10 is formed with a saddle 10A that straddles the outer peripheral surfaces of the two pipe ends 13A and 13B. The saddle 10A has an effect of facilitating the positioning of the pipe end. Reference numeral 14 denotes a stiffener made of SUS or the like which is fitted to the inner peripheral surfaces of both pipe ends 13A and 13B joined via the joint body 10.
It functions to prevent a part of 0 from rising inside the pipe end. Although not shown, an indicator for monitoring the above-mentioned melting state is also provided. The saddle 10
A and the stiffener 14 are provided as needed.

As the electric heating element 11, an electric heating fiber composed of a micro metal fiber and an aramid fiber can be used other than the nichrome wire. The current-carrying heating fiber has substantially the same electric heat characteristics as the nichrome wire, has the advantage that there is no risk of disconnection, and that it can be easily embedded in the joint body 10.

According to the electric fusion joint for a synthetic resin pipe of the present invention thus constructed, the pipe ends 13A and 13B are joined together as follows. That is, the pipe end 13
A and the outer peripheral surface of the pipe end 13B
Of these, each is cut into a tapered surface so as to match the shape of the outer peripheral surface. This makes it possible to remove a portion degraded by oxidation or the like. Next, the pipe ends 13A and 13B are butted through the joint body 10. In this case, since the pipe ends 13A and 13B are formed in a tapered surface shape, positioning can be performed reliably without providing a stopper or the like, and the pipe ends can be abutted with each other. This is particularly effective for a large-diameter tube. Then, an energizing cable (see FIG. 3) is connected to the terminal 12, and the energizing heating element 11 is energized to heat and melt the pipe ends 13A, 13B and the joint body 10. As a result, the tube ends 13A and 13B are fused and joined to each other.

A stiffener 14 is provided in the pipe ends 13A and 13B.
When inserting the pipe ends 13A, 13A
The stiffener 14 is inserted into B.

[0015]

As described above, according to the present invention, the following effective effects can be obtained by forming the joint main body in which the electric heating element is buried into a hollow truncated cone shape. Since the pipe end formed in the tapered surface shape is inserted into the joint body, the joint body can be easily mounted. Since it does not cover the outer peripheral surface of the pipe end unlike a conventional joint, it can be thin and light. Since the joining surface is a tapered surface, the joining area is wider than the parallel cylindrical surface of the conventional joint. Therefore, the joining strength is increased accordingly.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pipe end joined by an electric fusion joint for a synthetic resin pipe of the present invention.

FIG. 2 is a cross-sectional view showing a conventional electric fusion joint for a synthetic resin pipe attached to a pipe end.

FIG. 3 is a cross-sectional view showing a fusion state between an outer surface of a pipe end and an inner surface of a joint body.

FIG. 4 is a cross-sectional view showing a protrusion of the indicator.

[Explanation of symbols]

 1: pipe end 2: joint body 3: energized heating element 4: terminal 5: power supply 6: controller 7: indicator 8: through hole 9: ring-shaped projection 10: joint body 10A: saddle 11: energized heating element 12: terminal 13A: One pipe end 13B: The other pipe end 14: Stiffener

Claims (4)

[Claims] 1. A synthetic resin comprising a joint body made of the same material as the synthetic resin pipe and sandwiched between pipe ends of the synthetic resin pipes butted with each other, and a current-carrying heating element embedded in the joint body. In the pipe electric fusion joint, the joint body is formed in a hollow truncated cone shape, one inner peripheral surface of the pipe end portion is in close contact with the outer peripheral surface of the joint main body,
An electric fusion joint for a synthetic resin pipe, wherein the other outer peripheral surface of the pipe end is formed in a tapered surface shape so as to be in close contact with an inner peripheral surface of the joint main body. 2. The electric fusion joint for a synthetic resin pipe according to claim 1, wherein said joint main body has a saddle straddling over the outer peripheral surfaces of both pipe ends. 3. The heating element according to claim 1, wherein the heating element is made of a nichrome wire or a heating fiber.
Or an electric fusion joint for a synthetic resin pipe according to 2 above. 4. The stiffener according to claim 1, wherein a stiffener is fitted into the inner peripheral surfaces of the two pipe ends joined via the joint body. Electric fusion joint for synthetic resin tubes.