JPH05106775A - Electrically heating body incorporated pipe joint - Google Patents

Abstract

PURPOSE:To improve the workability of joint construction while restraining scattering in the performance of thermally fused parts in a pipe joint composed of electrically heating body generating Joule heat for thermally fusing a joint main body and a connected part of pipe, the electrically heating body being burried in the inner circumferential part of the joint main body made of thermoplastic resin and provided with a fitting part where a pipe made of thermoplastic resin is fitted. CONSTITUTION:A pipe slip off preventing means A for preventing a pipe 8 from being slipped off while it bites the joint main body 1 in association with the movement of the pipe 8 to be slipped off is provided, in the inner circumferential part of the joint main body 1, at a cold zone C being off from a heat zone H where an electrically heating body 4 is burried and heat is thereby generated when current is supplied thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric heating element-containing pipe joint, and more specifically, to an inner circumference of a joint body which is provided with a fitting portion into which a pipe made of a thermoplastic resin is fitted and which is made of a thermoplastic resin. The present invention relates to a pipe joint with an electric heating element, wherein a heat zone in which an electric heating element that generates Joule heat for fusing the joint body and the connected portion of the pipe is embedded is formed in the section.

[0002]

2. Description of the Related Art In such a pipe joint, as shown in FIGS.
As shown in FIG. 2, the connected portion (pipe end portion) of the pipe 8 to be connected is fitted into the fitting portion of the joint body 1 and the state is fixed.
While being fixedly held by using, the electric heating element 4 embedded in the joint body 1 is energized to generate Joule heat, and the heat heats the peripheral portion of the electric heating element 4 to soften the peripheral portion. Thermal expansion (thermal expansion in the radial direction), and
By the thermal expansion, the peripheral portion and the pipe end are brought into contact with each other to transfer the heat to the pipe end, and the pipe end is heated to be softened / thermally expanded (thermal expansion in the radial direction). The fusion of the joint body 1 and the connected portion of the pipe 8 has been performed.

[0003]

However, since the outer diameter of the connected portion (pipe end) of the pipe 8 varies,
Even if the pipe 8 having the end portion internally fitted to the fitting portion of the joint body 1 is fixed and held by using the fixing device 10, the clearance between the pipe end portion and the fitting portion of the joint body 1 becomes large. There is a risk that variations will occur and the relative position of the pipe end portion and the fitting portion of the joint body 1 in the axial direction will collapse.
Due to these, there is a problem that the performance of the fusion-bonded portion between the joint body 1 and the connected portion of the pipe 8 (hereinafter referred to as fusion-bonding performance) varies. Further, since the pipe 8 is fixed and held by using the fixing device 10, there is a problem that it is troublesome and the workability is poor, and a space for installing the fixing device 10 is required. If the outer peripheral surface of the pipe end is ground in advance to remove dirt,
The above-mentioned problem of fusion performance becomes more prominent because the outer diameter dimension varies more greatly. Further, since the conventional pipe joint is not provided with a sealing means for preventing the passage of foreign matters or gas, it is possible to prevent the fusion between the joint body 1 and the connected portion of the pipe 8. When foreign matter is mixed in the fitting part, or when the pipe 8 to be jointed is a gas pipe, etc., the gas that flows during the joint work (flows beyond the gas seal portion which is temporarily installed near the joint work place in the gas pipe). There was a problem that gas could leak. The present invention has been made by paying attention to such an actual situation, and a first object thereof is to solve the above-mentioned problems of variations in fusion bonding performance and workability of joint work all at once. Furthermore,
A second object is to solve the above-mentioned problems and also to solve the problems such as the inclusion of foreign matter in the fusion-bonded portion and the leakage of passing gas during joint work.

[0004]

A pipe joint containing an electric heating element according to the present invention has an inner peripheral portion of the joint body, a cold zone separated from the heat zone, and a movement in the pulling direction of the pipe. The first characteristic configuration is that the pipe withdrawal preventing means including the bite member that bites into the joint body to prevent the pipe from coming off is provided.

Further, a packing is provided in the cold zone together with the pipe withdrawal preventing means as a second characteristic structure.

[0006]

According to the first characteristic configuration, once the pipe having the connected portion internally fitted in the joint body tries to move in the pulling direction, the biting member bites into the joint body. Based on the bite, even if there is variation in the clearance between the connected portion and the fitting portion of the joint main body (the outer peripheral surface of the pipe is preliminarily shaved and removed, and the outer diameter dimension thereof has a larger variation. However, the relative positions of the two in the radial direction are fixed, and the pipe is prevented from coming off (that is, the relative positions of the both in the axial direction are prevented from collapsing). .. Therefore, the postures of the both when the fusion is performed are securely fixed and held without using the fixing device.
The workability at the time of constructing the pipe joint is improved as compared with the conventional one, and variations in the fusion bonding performance can be suppressed. Moreover, since the pipe withdrawal preventing means including the bite member is provided in the cold zone, the softening / deformation / thermal expansion of the resin in that portion is suppressed, and as a result, the pipe is prevented from coming off by the bite member. It is possible to prevent the action from disappearing, and to prevent the resin protruding and solidifying from the portion to the outside to prevent the appearance of the pipe joint after the construction from being impaired.

According to the second characteristic structure, since the packing is provided in the cold zone together with the pipe retaining means, the above-described actions of the pipe retaining means occur and, in addition, foreign matter and gas caused by the packing are prevented. Due to the sealing action, foreign matter is prevented from being mixed into the fusion-bonded portion and leakage of the passing gas during the joint work is avoided.

[0008]

According to the first characteristic configuration, as described above,
The problem of workability during the joint work and the problem of variation of the fusion bonding performance are solved all at once, and thus the first problem is achieved.

According to the second characteristic configuration, as described above, the problem of workability during the joint work and the problem of variation in the fusion bonding performance are solved, and foreign matter is mixed into the fusion bonding portion and the joint. Problems such as leakage of overcoming gas during construction are also solved, and thus the second problem is solved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a pipe joint containing an electric heating element according to the present invention, and the pipe joint is used as a joint when connecting pipes such as gas pipes. In the drawings, the portions denoted by the same reference numerals as the conventional example indicate the same or corresponding portions.

In FIG. 1, reference numeral 1 is a tubular joint body made of thermoplastic polyethylene resin, and the joint body 1 is a gas pipe 8 to be connected (specifically, a gas pipe 8 made of polyethylene resin). And hereinafter referred to simply as tube 8)
Fitting portions into which the connected portion (that is, the pipe end portion) is fitted are provided on both left and right sides.

At the inner peripheral portion of the joint body 1, an electric heating body 4 (specifically, a heating wire wound in a spiral shape) which generates Joule heat when energized is connected to the joint body 1. A central portion (the central portion usually corresponds to the outer periphery of the abutting portion of the pipe 8 in which a gap is generated, and that portion is partially expanded in diameter) and both end portions (both end portions thereof are in a cold zone C described later). It is embedded except for (corresponding), and the embedded portion is a heat zone H that generates heat by the Joule heat so as to fuse the joint body 1 and the fitting portion of the pipe 8 to each other. The reason why the electric heating body 4 is not embedded in the central portion of the joint body 1 is that the electric heating body 4 is overheated because the gap exists inside the central portion. In addition, the diameter of the central portion is slightly increased in order to avoid the overheating. Then, the outer peripheral side 2 of both ends of the electric heating body 4
An energizing terminal 5 to which a conductive wire 7 drawn from an external power source 11 shown in FIG. 3 is connected is provided at the location in an outwardly protruding state. Reference numeral 12 in FIG. 3 is a control box for controlling the conditions for energizing the electric heating element 4.

Two cold zones C separated from both ends of the joint body 1, that is, from the heat zone H to both ends.
Each of the inner peripheral portions thereof is provided with a pipe withdrawal preventing means A for retaining the pipe 8 once it has been inserted in the withdrawal direction. Specifically, the pipe retaining means A has an annular concave portion 22 formed in the inner peripheral portion of the cold zone C and having a conical surface whose inner diameter is reduced toward both ends as an inner bottom surface. A C-shaped steel biting member 21 (see FIG. 2) in side view is fitted therein. The biting member 21 has an annular protrusion 21a whose inner peripheral portion has a distal end protruding direction deflected toward the central portion of the joint body.
Are formed in parallel or in a spiral shape, and the bite member 2
1 is an annular projection 2 of which the rear surface is pressed against the inner bottom surface of the recess 22 as the tube 8 moves in the pulling direction.
1a bites into the outer peripheral surface of the pipe 8, and the pipe 8 is prevented from coming off based on the biting. The side view shape of the biting member 21 is
Other shapes may be used as long as they have the functions described above.

In the inner peripheral portion of the cold zone C of the joint body 1, foreign matter or gas passes between the joint body 1 and the pipe 8 at a position outside the installation position of the pipe retaining means A. A packing 31 (specifically, an O-ring having a circular cross section) that suppresses the above is provided. In addition, the packing 31 has a structure in which the pipe 8 is inserted into the annular recess 32 formed in the inner peripheral portion of the joint body 1 in a state where the pipe 8 is allowed to be inserted.
It is housed so as to be in close contact with the outer peripheral surface thereof, and its cross-sectional shape can be variously changed other than circular.

When the pipe 8 is connected using such a pipe joint, as shown in FIG. 3, the connected portions (pipe end portions) of the pipe 8 to be connected are fitted to the fitting portions on both sides of the joint body 1. While fitting and holding the state by the action of the pipe removal preventing means A,
The electric heating element 4 is energized to generate Joule heat,
The heat heats the peripheral portion of the electric heating body 4 to soften / thermally expand (thermally expand in the radial direction) the peripheral portion, and further, the thermal expansion causes the peripheral portion and the pipe end to come into contact with each other. The heat is transmitted to the pipe end portion, and the pipe end portion is heated to be softened / thermally expanded (thermal expansion in the radial direction), whereby the joint body 1 and the connected portion of the pipe 8 are connected. Fuse it.

Thus, when performing joint work, even if the pipe 8 having the connected portion internally fitted to the joint body 1 tries to move in the pull-out direction, the biting member 21 causes the outer periphery of the joint body 1 to move. As a result, the joint body 1 and the pipe 8 are prevented from collapsing in the radial relative position and the axial relative position between the joint body 1 and the pipe 8. Therefore, the postures of the both when the fusion is performed are securely held without using the conventional fixing device 10 (see FIG. 5), and thus workability at the time of fitting the pipe joint is improved as compared with the conventional case. In addition, variations in the fusion performance can be suppressed. Further, since the pipe disengagement prevention means A is provided in the cold zone C, the resin in that portion, that is, the annular recess 22 and the bite member 2 is provided.
1 is suppressed from being softened and deformed, the retaining action of the pipe 8 by the biting member 21 is prevented from being lost, and further, softening and thermal expansion of the resin in the portion is suppressed, and the resin from the portion to the outside is suppressed. The protrusion is suppressed and the appearance of the pipe joint after construction is not impaired. When the pipe 8 to be connected is a gas pipe buried underground, the conventional fixing device 1
Since it is not necessary to provide 0 (see FIG. 5), it is possible to reduce the size of a hall (not shown) that is recessed in the ground as a work space for performing joint work and the like. In addition, the packing 31 prevents foreign matter or gas from leaking into the fusion-bonded portion or leaking gas during the joint work due to the sealing action of foreign matter or gas.

Next, another embodiment of the present invention will be described. The pipe retaining means A is configured such that the biting member 21 is pivotally supported on the joint body 1 so as to be swingable when the connected portion of the pipe 8 is inserted, and the retaining function can be exerted. May be That is, the annular recess 22
There may be an embodiment in which the joint body 1 is not recessed. Further, the electric heating element 4 embedded in the joint body 1 may be a cylindrically-shaped integral heater separately arranged on both left and right sides.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a pipe joint containing an electric heating element according to the present invention together with a pipe to be connected.

FIG. 2 is a vertical cross-sectional view showing a main part of a pipe slip-out prevention means in the pipe joint.

FIG. 3 is an explanatory view showing a state in which pipe connection is performed by the pipe joint.

FIG. 4 is a vertical cross-sectional view showing a conventional pipe joint with an electric heating element together with a pipe to be connected.

FIG. 5 is an explanatory view showing a state in which a conventional pipe joint is used for pipe connection.

[Explanation of symbols]

 1 Joint body 4 Electric heating body 8 Pipe 21 Biting member 31 Packing A Pipe retaining means C Cold zone H Heat zone

Claims (2)

[Claims] 1. A joint main body (1) is provided on an inner peripheral portion of a joint main body (1) which is provided with a fitting portion into which a pipe (8) made of a thermoplastic resin is fitted and which is made of a thermoplastic resin. Said tube (8)
An electric heating element-containing pipe joint in which a heating zone (H) in which an electric heating element (4) for generating Joule heat for fusing with a connected part of is joined is formed, the joint body (1) of In the inner peripheral portion, in the cold zone (C) separated from the heat zone (H), the joint body (1) is moved along with the movement of the pipe (8) in the pulling direction.
A pipe joint containing an electric heating element, which is provided with a pipe withdrawal preventing means (A) comprising a bite member (21) which bites into the pipe to prevent the pipe (8) from coming off. 2. The electric heating element-containing pipe joint according to claim 1, wherein the cold zone (C) is provided with a packing (31) together with the pipe retaining means (A).