JPH1113982A - Electrically fused joint provided with clamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically fused joint capable of surely and firmly fusing the joint with a plastic pipe without a fixing tool used. SOLUTION: A male screw 7 and a tapered inner surface 8 tapered inwardly, are formed in the end part 6 of a joint main body 2, the female screw 11 of a fixing body 9 having an inner annular part 12 formed with an inner circumferential surface 16, in which an outer annular part 10 formed with a female screw 11, a tapered inner surface 13, and a plastic pipe 20 are inserted, is screwed in the male screw 7 of the joint main body 2 so as to allow the tapered outer surface 13 to be brought into contact with the tapered inner surface 8, furthermore, it is screwed in much more so as to allow the inner annular part 12 to be contracted in diameter, and the outer surface 21 of the plastic pipe 20 is intensively pressed by the inner circumferential surface 16 of the inner annular part 12, so that the plastic pipe 20 is thereby fixed to an electrically fused joint 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-fusion joint for electro-fusion with a thermoplastic resin pipe, and more particularly, to a joint body made of a thermoplastic resin and a fixed body formed of a rigid resin. The present invention relates to an electric fusion joint in which an electric heating element is buried in a joint inner surface of the joint main body and is electrically fused to a thermoplastic resin pipe.

[0002]

2. Description of the Related Art There are various types of pipe joints to be connected to a thermoplastic resin pipe. An electric heating element such as a nichrome wire is buried in a joint inner surface, and a thermoplastic resin pipe is inserted into this. An electric fusion joint is widely used in which an electric current is applied to the joint to generate heat to fuse the joint to the pipe.

However, there is naturally an allowable error in the outer diameter of the connection end of the thermoplastic resin pipe, and therefore the inner diameter of the inner surface of the joint of the electrofusion joint is determined to be large, and further processed to this size. Tolerance is added. For this reason, when the resin tube is inserted into the electrofusion joint, a gap is generated between the tube and the joint, and the tube and the joint are not kept coaxial or the positioning in the axial direction is uncertain.

In this state, when the electric heating element is energized to heat and melt the inner surface of the joint of the electrofusion joint and the outer surface of the resin tube facing the same, there is no gap between the inner surface of the joint and the outer surface of the resin tube. Due to the uniformity, the melting on the outer surface of the resin tube becomes uneven, and a defective fusion portion may be generated when the molten resin is cooled and solidified. Further, before the molten resin is cooled to a temperature lower than the crystallization temperature, the joint or the resin pipe may move due to the pressure or external force of the molten resin, and the connection interface may move to make it impossible to perform a firm fusion connection.

[0005] In order to prevent such defective fusion, fusion is often performed by using a fusion tool 31 as shown in FIG. In FIG. 5, reference numeral 32 denotes an electric fusion joint, and reference numerals 33 and 34 denote thermoplastic resin tubes.

[0006] The fusing tool described above has many problems as described below.
As shown in JP-A-5083 and JP-A-7-251456, a wedge is inserted between the joint inner diameter and the outer surface of the resin tube at the connection end of the electric fusion joint to insert the resin tube into the electric fusion joint. As shown in the fixing method and Japanese Patent Application Laid-Open No. 7-329186, a female screw is provided on the inner peripheral surface of the electric fusion joint, and a male screw processed at the tip of the resin pipe is screwed into the female screw to perform electric fusion. A method of fixing a resin pipe to a joint has been proposed.

[0007]

As described above, in order to prevent defective fusion, a tool 3 for fusion work as shown in FIG.
When using No. 1, it is necessary to prepare these tools for each size of the resin pipe. Also, it takes a considerable amount of time to cool to a temperature below the crystallization temperature at which sufficient adhesive strength can be obtained, and during this time, the tool for the fusion work cannot be removed from the resin pipe, so proceed to the next step. Disappears. For this purpose, it is necessary to prepare a plurality of tools for the same size of the resin pipe. Therefore, the method using the welding tool is expensive.

Further, the method using the welding tool is inconvenient to use in a narrow working space, not only requires a lot of man-hours for mounting work, but also takes time and effort to collect the tool after cooling. Many man-hours are required for piping work.

Next, as shown in JP-A-6-265083 and JP-A-7-251456, a wedge is inserted between the inner diameter of the joint and the outer surface of the resin pipe at the connection end of the electric fusion joint. In the method of fixing the resin tube to the electric fusion joint, the former uses a retaining member having a tapered stiffener portion as a wedge, and the retaining member has a peculiar shape and is expensive. is there. Also, in the latter, a plurality of wedges are individually driven and inserted into the same circumferential portion, and a plurality of wedges are formed so that a gap between the electric fusion joint and the resin pipe is uniform. Is a very cumbersome task, especially in confined workspaces.

[0010] Further, as shown in JP-A-7-329186, a female screw is provided on the inner peripheral surface of the electrofusion joint,
In the method of fixing the resin pipe to the electric fusion joint by screwing the male thread processed at the tip of the resin pipe into this, the male thread must be processed after cutting the resin pipe to the length according to the piping site Not only that, work on site becomes troublesome.

The problem to be solved by the present invention is the above-mentioned various problems when performing electric fusion splicing with a resin pipe using various conventional electric fusion joints.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and has an electric heating element embedded in a joint inner surface of a thermoplastic resin joint body and inserted into the joint body. In the electrofusion joint to be electrofused with the thermoplastic resin pipe, a male screw is formed on an outer peripheral surface of an end portion of the joint body, and a tapered inner surface which becomes thinner inward is formed on an inner peripheral surface. A fixed body formed of a rigid resin having an outer ring portion formed with a female thread to be screwed with a male screw, an inner ring portion formed with a tapered outer surface in contact with the tapered inner surface, and an inner peripheral surface into which the resin tube is inserted. The female thread is screwed into the male thread and screwed in, and the inner peripheral surface of the inner ring portion is pressed against the outer surface of the inserted resin pipe by the two tapered surfaces to fix the resin pipe.

In this case, it is preferable to provide a plurality of radial cutting grooves which are opened in the distal direction in parallel with the axial direction of the inner ring portion of the above-mentioned fixed body and are substantially equally spaced in the circumferential direction. In addition, the tapered inner surface of the joint body and the tapered outer surface of the inner ring portion of the fixed body are formed of two tapered surfaces with different taper angles, and the taper angle of the inner ring portion distal end is set to the far side. It is preferable that the taper angle is larger than the taper angle, and that the taper inner surface and the taper outer surface are in contact with each other at the smaller taper angle.

Further, it is preferable that a plurality of streak-like projections having a substantially triangular or trapezoidal cross section are provided on the inner peripheral surface of the fixed body in parallel with or inclined to the axial direction of the fixed body, or circumferentially. Further, a plurality of projections or grooves having a substantially rectangular or trapezoidal cross section may be provided on the outer peripheral surface of the outer ring portion of the fixed body in parallel with the axial direction of the fixed body.

[0015] With the above structure, first, the female screw of the outer ring portion of the fixed body formed of a rigid resin is screwed into the external thread of the outer peripheral surface of the thermoplastic resin joint main body. When a thermoplastic resin tube is inserted into this electrofusion joint with clamp, which has a fixed body attached to it, with the fixed body slightly loosened, and the fixed body is screwed in, the tapered outer surface of the inner ring of the fixed body becomes a joint. When the fixed body is further screwed in contact with the tapered inner surface of the inner peripheral surface at the end of the main body, the inner ring portion of the fixed body is deformed to reduce the diameter by the action of the two tapered surfaces that are in contact with each other. The outer surface of the resin tube into which the inner peripheral surface is inserted is strongly pressed to fix the resin tube to the electrofusion joint.

In this case, since the inner ring portion of the fixed body is reduced in diameter in the same state as the joint body, the joint body and the resin pipe are fixed concentrically. In this state, when an electric heating element embedded in the inner surface of the joint of the joint body is energized to generate heat, the outer surface of the thermoplastic resin pipe facing the inner surface of the joint of the thermoplastic resin joint body is melted. When the power is turned off and heat is released and cooled, the molten resin crystallizes and is fixed below the crystallization temperature, and the joint body and the pipe are firmly connected. And since both were fixed concentrically by the fixed body, the melting and solidification of the resin between the two was uniform, and there was no movement between the two, so they solidified without defects, and the joint and the pipe were concentric. It is surely fusion spliced.

Further, since the inner ring portion of the fixed body is provided with a plurality of split grooves substantially equally spaced in the circumferential direction, when the fixed body is screwed into the joint body, the inner ring portion of the fixed body is formed. Can be very easily reduced in diameter by the action of both tapered surfaces.

The contact surface between the tapered inner surface of the joint main body and the tapered outer surface of the inner ring portion of the fixed body first occurs on the inner side of the inner ring portion having a small taper angle, and these two surfaces are formed by screwing the fixed body into the joint body. The inner ring portion is reduced in diameter by the action of the tapered surface, and the outer peripheral surface of the resin tube having a normal outer diameter is strongly pressed against the inner peripheral surface of the inner ring portion of the fixed body, thereby fixing the resin tube to the joint body.

However, in the case of a resin pipe having a relatively small outer diameter, it may not be possible to fix the resin pipe to the joint body by reducing the diameter of the inner ring portion due to the action of the two tapered surfaces having a small taper angle. is there. In this case, when the fixed body is further screwed into the joint body, and the tapered outer surface is brought into contact with the tapered inner surface of the joint body at the distal end portion of the inner ring portion having a large taper angle, the inner ring portion is reduced in diameter. Due to the large angle, the degree of diameter reduction is large, and the resin pipe having a relatively small outer diameter is also reliably fixed to the joint body by the inner ring part whose diameter is greatly reduced.

The plurality of stripe-like projections having a substantially triangular or trapezoidal cross section provided on the inner peripheral surface of the fixed body support the resin pipe even before the fixed body is screwed to fix the resin pipe and the joint. For arranging the resin pipe and the joint almost concentrically,
When connecting a resin tube with a relatively large outer diameter, when the resin tube is inserted, the portion where the streak-like projections hinder
Since its volume is relatively small, it is easily crushed by the inserted resin tube.

Since the outer peripheral surface of the outer ring portion of the fixed body is provided with a projection or groove having a substantially rectangular or trapezoidal cross section, the fixed body can be easily screwed into the joint body by using a tool. .

[0022]

Next, an embodiment of the present invention will be described. FIG. 1 is a partial longitudinal sectional view showing one embodiment of an electrofusion joint with a clamp of the present invention, and shows a state where a resin pipe is inserted into the joint. 2 is an enlarged partial longitudinal sectional view of FIG. 1, and FIG. 3 is a perspective external view of the fixed body shown in FIG. FIG. 4 is a partial longitudinal sectional view showing a state where the resin pipe of the joint shown in FIG. 1 is not inserted.

1 to 4, reference numeral 1 denotes an electrofusion joint with a clamp, and 2 denotes a joint body made of a thermoplastic resin.
An electric heating element 4 is embedded in the inner surface 3 of the joint.
5 is the connection terminal. A male screw 7 is formed on the outer peripheral surface of the end portion 6 of the joint main body 2, and a tapered inner surface 8 tapering inward is formed on the inner peripheral surface. The tapered inner surface 8
Is composed of two tapered inner surfaces having different taper angles indicated by 8a and 8b in FIG.
The taper inner surface α of a is smaller than the taper angle β of the taper inner surface 8b.

Reference numeral 9 denotes a fixed body. The outer ring 10 has a female screw 11 screwed to the external thread 7 of the joint body 2, and the inner ring 12 has a tapered inner surface 8 of the joint body 2. The tapered outer surface 13 is formed in contact with the outer surface. The tapered outer surface 13 is also composed of two tapered outer surfaces 13a and 13b, and the respective taper angles are α and β, similarly to the tapered inner surfaces 8a and 8b. However, the contact surface between the tapered inner surface 8a and the tapered outer surface 13a is the tapered inner surface 8b.
And comes into contact before the contact surface with the tapered outer surface 13b.

Further, as shown in FIG. 3, a radial cutting groove 15 which is parallel to the axial direction and is opened in the direction of the tip 14 is formed on the inner ring portion 12 of the fixed body 9 in the circumferential direction at substantially equal intervals. A plurality of them (four in the fixed body 9 shown in FIG. 3) are provided apart from each other.

Further, as shown in FIG. 4, the fixed body 9 has a plurality of stripe-shaped projections 17 having a substantially triangular cross section on the inner peripheral surface 16 in the axial direction (four in the example shown in FIG. 4). A projection 19 having a substantially rectangular cross section is provided on the outer peripheral surface 18 of the outer ring portion 10 of the fixed body 9 as shown in FIG.

Next, the operation of the above-described embodiment shown in FIGS. 1 to 4 will be described. The female thread 11 of the fixed body 9 is screwed into the external thread 7 of the outer peripheral surface 18 of the joint body 2,
A fixed body 9 is attached to the joint body 2. As shown in FIGS. 1 and 2, the thermoplastic resin pipe 20 is inserted in a state where the fixed body 9 is slightly loosened, and the fixed body 9 is screwed. 9 is the tapered inner surface 8 of the joint body 2
When the fixing body 9 is further screwed in,
Due to the action of both the tapered surfaces 3 and 8, the inner ring portion 12 of the fixed body 9 is deformed so as to reduce the diameter, and the inner peripheral surface 16 strongly presses the outer surface of the resin tube 20 into which the resin tube is inserted. 20 is fixed to the electrofusion joint 1.

In this case, the diameter of the inner ring portion 12 of the fixed body 9 is reduced concentrically with the joint body 2, so that the joint body 2 and the resin pipe 2
Zero is fixed concentrically. In this state, when the electric heating element 4 embedded in the joint inner surface 3 of the joint body 2 is energized to generate heat, the joint inner surface 3 of the joint body 2 made of thermoplastic resin and the thermoplastic resin pipe 20 facing the joint inner surface 3 Is melted.

When the power is turned off and the heat is released and cooled, the molten resin crystallizes and solidifies at a temperature lower than the crystallization temperature, and the joint body 2 and the resin pipe 20 are firmly connected. Since the two are completely concentrically fixed by the fixing body 9, the resin is solidified and melted and solidified uniformly between the two. Are firmly and fusion-bonded concentrically.

The inner ring 12 of the fixed body 9 is provided with a plurality of split grooves 15, so that when the fixed body 9 is screwed into the joint body 2, the inner ring 12 of the fixed body 9 is tapered. 8 and 1
By the action of 3, the diameter can be reduced very easily.

The above-mentioned contact surface between the tapered inner surface 8 and the tapered outer surface 13 is first formed at the tapered inner surface 8a and the tapered outer surface 13a having a small taper angle α.
The inner ring portion 12 is reduced in diameter by the action of the two tapered surfaces 8a and 13a by screwing into the inner surface, and the inner peripheral surface 16 of the fixed body 9 is strongly pressed against the outer surface 21 of the resin tube 20 having a normal outer diameter. Then, the resin pipe 20 is fixed to the joint body 2.

However, the resin tube 2 whose outer diameter is relatively small
At 0, the diameter of the inner ring portion 12 due to the action of the two tapered surfaces 8a and 13a having a small taper angle α may not be enough to fix the resin pipe 20 to the joint body 2.
In this case, if the fixed body 9 is further screwed into the joint body 2 and the tapered outer surface 13b having a large taper angle β is brought into contact with the tapered inner surface 8b to reduce the diameter of the inner ring portion 12, the taper angle β is large. The resin tube 20 having a large diameter reduction and a relatively small outer diameter is also securely fixed to the joint body 2 by the inner ring 12 having a large diameter reduction.

The plurality of strip-shaped projections 17 provided on the inner peripheral surface 16 of the fixed body 9 support the resin pipe 20 even before the fixed body 9 is screwed to fix the resin pipe 20 and the joint 1. For arranging the pipe 20 and the joint 1 almost concentrically,
When the resin pipe 20 having a relatively large outer diameter is connected, a portion of the hindrance of the streak-like projection 17 is relatively small when the resin pipe 20 is inserted. 20 for easy crushing.

Since the projection 19 is provided on the outer peripheral surface 18 of the outer ring portion 10 of the fixed body 9, the fixed body 9 can be easily screwed into the joint body 2 by using a tool.

[0035]

According to the electrofusion joint with a clamp of the present invention, when the resin tube is inserted into the joint, the two are already almost concentric, and the two can be easily and reliably fixed in the concentric state. Wearing will surely be strong. Moreover,
This fixation does not require special fixing tools or wedge-shaped retaining members.It is easy to work even in a narrow work space, and there is no need to process screws or the like on the resin pipe, which reduces the number of work steps. It requires less and is extremely economical.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing one embodiment of an electrofusion joint with a clamp of the present invention.

FIG. 2 is an enlarged partial longitudinal sectional view of FIG.

FIG. 3 is a perspective external view of the fixed body shown in FIG. 1;

FIG. 4 is a partial longitudinal sectional view showing a state where a resin pipe of the joint shown in FIG. 1 is not inserted.

FIG. 5 is a perspective external view showing a state in which the joint and the resin pipe are fixed by using a welding tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric fusion joint with clamp 2 Joint main body 3 Joint inner surface 4 Electric heating element 6 End part 7 Male thread 8, 8a, 8b Tapered inner surface 9 Fixed body 10 Outer ring part 11 Female thread 12 Inner ring part 13, 13a, 13b Taper Outer surface 14 Tip 15 Cut groove 16 Inner peripheral surface 17 Streak-like projection 18 Outer peripheral surface 19 Projection 20 Resin tube 21 Outer surface

Claims (5)

[Claims] 1. An end portion of a joint body made of a thermoplastic resin, wherein an electric heating element is embedded in an inner surface of the joint body made of a thermoplastic resin, and is electrically fused to a thermoplastic resin tube inserted into the joint body. An external thread is formed on the outer peripheral surface, and an inner peripheral surface is formed with a tapered inner surface that becomes thinner inward, and an outer ring portion formed with a female screw that is screwed with the external thread and a tapered outer surface that comes into contact with the tapered inner surface And a fixed body formed of a rigid resin having an inner ring portion formed with an inner peripheral surface into which the resin tube is inserted,
The female screw is screwed into the male screw and screwed in, and the inner peripheral surface of the inner ring portion is pressed against the outer surface of the inserted resin tube by the both tapered surfaces to fix the resin tube. Electrofusion joint with clamp. 2. A radial split groove which is opened in a tip direction parallel to an axial direction of an inner ring portion of the fixed body,
2. The electrofusion joint with clamp according to claim 1, wherein a plurality of the joints are provided at substantially equal intervals in a circumferential direction. 3. The tapered inner surface of the joint body and the tapered outer surface of the inner ring portion of the fixed body are each formed of two tapered surfaces having different taper angles, and the taper angle of the tip portion of the inner ring portion is adjusted. The electrofusion joint with a clamp according to claim 1 or 2, wherein the taper angle is larger than the taper angle on the back side, and the tapered inner surface and the tapered outer surface are configured such that the smaller taper angle comes in contact with the tapered inner surface first. . 4. A plurality of streak-like projections having a substantially triangular or trapezoidal cross section are provided on the inner peripheral surface of the fixed body in parallel with or inclined to the axial direction of the fixed body, or circumferentially. An electric fusion joint with a clamp according to any one of claims 1 to 3. 5. The fixed body according to claim 1, wherein a plurality of projections or grooves having a substantially rectangular or trapezoidal cross section are provided on an outer peripheral surface of an outer ring portion of the fixed body in parallel with an axial direction of the fixed body. Electric fusion joint with clamp.