JP2001141168A - Electric fusion joint, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric fusion joint which can easily join composite pipes with excellent internal pressure resistance in a condition excellent in internal pressure resistance, and its manufacturing method. SOLUTION: In the electric fusion joint 10 in which a socket 10A is provided on both ends, and a bobbin 20 comprising an electric heating wire spirally wound over a predetermined length is embedded in a thermoplastic resin wall forming the sockets 10A, a cylindrical body 112 comprising a wound oriented thermoplastic resin sheet is embedded in the thermoplastic resin wall across the bobbins 20 outside thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrofusion joint suitably used for connecting composite pipes having excellent internal pressure resistance and a method for producing the same.

[0002]

2. Description of the Related Art Pipes, hoses, and other pipes used for flowing and transporting various substances such as liquids and gases are required to have internal pressure resistance so that they are not damaged by the pressure of the substances flowing inside. You. In particular, like oil-resistant pipes, water supply pipes, etc.
When conveying a high-pressure fluid, high internal pressure resistance is required.

[0003] Since synthetic resin generally has lower tensile strength and the like than metal, the synthetic resin pipe is made thicker in order to secure strength against internal pressure and the like. Therefore, the cost may increase depending on the internal pressure condition and the bore size.

[0004] For example, in Japanese Patent Application Laid-Open No. H08-11250, a fiber reinforcing layer and a wire reinforcing layer are provided between an inner layer and an outer layer each formed of a flexible material such as a synthetic resin. A composite tube is disclosed.

In such a composite pipe, the provision of the fiber reinforcing layer and the wire reinforcing layer improves the internal pressure resistance or the external pressure resistance. However, since the fiber reinforcing layer is arranged by braiding a fiber having an appropriate thickness or wound in a spiral shape, there is a problem that the fiber reinforcing layer itself becomes thick. Further, the fiber reinforcing layer formed by bundling the fibers also has a problem that the axial strength along the longitudinal direction of each fiber is greater than the strength in the circumferential direction. Moreover, since the wire reinforcing layer is laminated on the fiber reinforcing layer, the overall thickness is large, and the overall weight is large, so that the handling is not easy.
There is also a problem that economic efficiency is impaired.

Accordingly, the present inventors have filed a Japanese Patent Application No. 11-95.
No. 451, a composite having excellent internal pressure resistance in which an intermediate layer formed by spirally winding a stretched olefin-based resin sheet between inner and outer pipes made of synthetic resin is laminated without increasing the wall thickness. Suggested tube. When the composite pipes are connected to each other using an electric fusion joint in which a heating wire is embedded in conventional polyethylene to form a conduit, the composite pipe portion is reinforced with a stretched olefin-based resin sheet. Although the internal pressure resistance is high, the internal pressure resistance of the electro-fused joint is insufficient unless the thickness is considerably increased. This is problematic in that molding tends to occur and molding is difficult.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and allows a composite pipe having excellent internal pressure resistance to be formed by a simple operation in a state having excellent internal pressure resistance. An object of the present invention is to provide an electric fusion joint that can be joined and a method of manufacturing the same.

[0008]

The invention according to claim 1 of the present application (the present invention 1) has receiving ports provided at both ends, and a predetermined length is provided in a thermoplastic resin wall forming the receiving ports. An electric fusion joint in which a bobbin made of a spirally wound heating wire is embedded, and the stretched thermoplastic resin is stretched over the two bobbins in a thermoplastic resin wall outside thereof. This is an electrofusion joint in which a tubular body made of a rolled sheet is embedded.

The invention described in claim 2 of the present application (Invention 2)
Is a composite pipe structure in which a portion in which the tubular body is embedded has a composite tubular structure in which a tubular body composed of a roll of a stretched thermoplastic resin sheet is laminated between inner and outer layers formed of a thermoplastic resin. It is an electrofusion joint of Invention 1.

The invention described in claim 3 of the present application (the present invention 3)
Forming a pair of bobbins connected in series by spirally winding a heating wire, and forming the pair of bobbins by winding a stretched thermoplastic resin sheet between inner and outer layers formed of a thermoplastic resin. A step of mounting in a composite pipe in which a cylindrical body composed of is laminated, and inserting this into an injection molding die,
And a step of injecting a thermoplastic resin into the injection molding die.

The invention described in claim 4 of the present application (Invention 4)
Forming a pair of bobbins connected in series by spirally winding a heating wire, and winding a stretched thermoplastic resin sheet outside the pair of bobbins so as to straddle the pair of pobbins; Producing an electrofusion joint comprising: forming a shaped body; inserting the pair of bobbins and the cylindrical body into an injection mold; and injecting a thermoplastic resin into the injection mold. Is the way.

In the present invention, polyethylene is preferably used as the thermoplastic resin constituting the joint body of the electrofusion joint. However, the thermoplastic resin is not limited to polyethylene. For example, olefin resins other than polyethylene, vinyl chloride resins ,
Polyamide or the like may be used.

In the present invention, as the thermoplastic resin constituting the stretched thermoplastic resin sheet forming the cylindrical body, for example, polyethylene is preferably used, but an olefin-based resin other than polyethylene and other stretchable thermoplastic resins can be used. It may be a thermoplastic resin. The thermoplastic resin is a resin of the same kind as the thermoplastic resin forming the joint body of the electric fusion joint, and preferably has a fusion compatibility.

[0014]

According to the first aspect of the present invention, there is provided an electro-fusion joint comprising a roll of a stretched thermoplastic resin sheet in a thermoplastic resin wall which straddles both bobbins to form a joint body outside thereof. When the pipe is formed as a joint that connects the composite pipes that are excellent in internal pressure resistance and that are excellent in internal pressure resistance by the electric fusion method by embedding the shape body, There is no risk of breakage even if the fluid flows at high pressure, and the thermoplastic resin layer exists on the tubular body, so the tubular body is protected from external force, and the tubular body may be damaged by external force. ,
There is no risk of damage.

[0015] In the electrofusion joint according to the second aspect of the present invention, the portion in which the tubular body is embedded is a tubular body formed by winding a stretched thermoplastic resin sheet between inner and outer layers formed of a thermoplastic resin. Due to the laminated composite pipe structure, the internal pressure resistance is further improved.

According to a third aspect of the present invention, there is provided a method for manufacturing a fusion spliced joint, comprising the steps of spirally winding a heating wire to form a pair of bobbins connected in series, and forming the pair of bobbins of a thermoplastic resin. Mounting in a composite pipe in which a tubular body made of a roll of a stretched thermoplastic resin sheet is laminated between the inner and outer layers, and inserting the same into an injection molding die; By including the step of injecting the plastic resin, an electro-fusion joint having excellent internal pressure resistance can be manufactured by simple operations.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an electro-fusion joint, comprising: a step of spirally winding a heating wire to form a pair of bobbins connected in series; Winding a stretched thermoplastic resin sheet outside thereof to form a tubular body, inserting the pair of bobbins and the tubular body into an injection mold, and inserting a thermoplastic resin into the injection mold. By including the step of injecting the resin, it is possible to easily manufacture an electrofusion joint having excellent internal pressure resistance by a simple operation.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of the electrofusion joint of the present invention. As shown in FIG. 1, the electrofusion joint 10 of this example is a socket-type joint having sockets 10A at both ends.

The wall constituting the electrofusion joint 10 is a cylindrical body 1 made of a roll of a stretched polyethylene sheet between an inner layer 111 and an outer layer 113 formed of polyethylene.
The composite pipe 11 includes an injection molded layer 12 laminated by injection molding inside the composite pipe 11.

As shown in FIG. 7, the inner layer 1 of the composite pipe 11 is
The cylindrical body 112 laminated between the outer layer 11 and the outer layer 113 is
A stretched polyethylene sheet in the shape of a strip with an appropriate width dimension,
It is spirally wound so as to have an inclination angle of 30 to 90 ° with respect to the axial direction of the inner layer 111, and further, a stretched polyethylene sheet is spirally wound so that the inclination direction is opposite to that of the drawn polyethylene sheet. It is formed in a layer structure.

The composite pipe 11 having such a structure is a cylindrical body 112 in which a stretched polyethylene sheet having excellent tensile strength is spirally wound around a polyethylene inner layer 111.
Are laminated, the inner layer 111 is
Has been reinforced. Therefore, the composite pipe 11 has excellent internal pressure resistance.

In the composite tube 11, since the outer layer 113 made of polyethylene is laminated on the tubular body 112, the tubular body 112 is protected from external force, and the tubular body 112 may be damaged by external force. There is no risk of damage.

In the polyethylene wall forming the injection molding layer 12 of the sockets 10A, 10A of the electrofusion joint 10, a pair of bobbins 20, which are formed by a spirally wound resin-coated heating wire 22 over a predetermined length, are provided. 20 are buried for a certain length.

The electric fusion joint 10 comprises two bobbins 20, 20.
The tubular body 112 made of a roll of a stretched polyethylene sheet is embedded in the composite pipe 11 constituting the outer wall of the tubular body so as to straddle.

At both ends of the electric fusion joint 10, terminals 25, 25 connected to the pair of bobbins 20, 20 are provided.
Indicator part 1 formed integrally with injection molding layer 12
21 and 121 are provided so as to be exposed on the outer peripheral surface.

An example of a method for manufacturing the electrofusion joint 10 shown in FIG. 1 will be described below with reference to FIGS. First, as shown in FIG. 2, a resin-coated heating wire 22 is spirally wound on a winding core 21 by rotating the winding core 21 in the circumferential direction. Heating wire 23
To form a pair of windings 20 ', 20' connected to each other, and fix the resin-coated heating wires 22 adjacent to the windings 20 ', 20' by ironing stops 24.

Next, as shown in FIG.
After removing the resin coating layers at the ends of the resin-coated heating wires 22 at both ends of 0 'and 20' to expose the metal wires, and connecting the terminals 25 and 25 to the metal wires,
To obtain a pair of bobbins 20, which are made of a spirally wound resin-coated heating wire.

Next, as shown in FIG. 4, the pair of bobbins 20 shown in FIG. The composite pipe 11 has terminal forming holes 11 at both ends.
4,114 and indicator forming holes 115,115
Are provided. Terminal forming holes 114, 11
By inserting terminals 25, 25 connected to the pair of bobbins 20, 20 from inside into the pair 4, the pair of bobbins 20, 20 are fixed in the composite pipe 11.

In the inserted terminals 25, 25,
Screws 116, 116 are screwed in from the outside, and external indicator pins 117, 117 are inserted into the indicator forming holes 115, 115, and the indicators are closed. At the tips of the indicator pins 117, 117, holes for forming an indicator are provided.

Next, as shown in FIG. 5, the composite pipe 11 in this state and a pair of bobbins 2 fixed in the composite pipe 11 are formed.
0 and 20 are inserted into the outer mold 31 of the injection mold 30. In this open state, the inner die 32 is in a reduced diameter state. Next, as shown in FIG. 6, the inner die 32 is advanced to the outer die 31, and the inner die 32 is expanded so that the inner die 32 is clamped.

After an example of injection molding in which polyethylene is injected into the injection mold 30 composed of the outer mold 31 and the inner mold 32, the mold is opened and the mold is removed, screws 116 and 11 are formed.
6 and the indicator pins 117, 117, the injection molded layer 12 is laminated inside the composite pipe 11, as shown in FIG. 1, and the spiral of the resin-coated heating wire 22 over a predetermined length in the polyethylene wall. The electric fusion joint 10 in which the pair of bobbins 20 and 20 made of a spirally wound material are embedded is obtained.

The electric fusion joint 10 includes two bobbins 20,
A tubular body 112 made of a roll of a stretched polyethylene sheet is embedded in a composite tube 11 that straddles the 20 and forms an outer wall thereof. For this reason, this electrofusion joint 10 is excellent in internal pressure resistance,
When a pipe is formed by using a composite pipe similar to that shown in FIG. 7 as a joint for connecting the pipes by an electric fusion method, there is no possibility that the pipe may be broken even if a fluid flows through the pipe at a high pressure. In addition, since the outer layer 113 made of polyethylene is laminated on the tubular body 112, the tubular body 112 is protected from external force, and there is no possibility that the tubular body 112 is damaged or damaged by the external force.

FIG. 8 is a sectional view showing another example of the electrofusion joint of the present invention. As shown in FIG. 1, the electrofusion joint 40 of this example is a socket-type joint having sockets 40A, 40A provided at both ends.

In the polyethylene wall 41 forming the receiving ports 40A, 40A of the electrofusion joint 40, a pair of bobbins 50, 50 made of a spirally wound resin-coated heating wire 52 are provided over a predetermined length. Buried across.
A cylindrical body 60 made of a rolled stretched polyethylene sheet is embedded in the polyethylene wall 41 of the electric fusion joint 40 so as to straddle both bobbins 50 and 50.

Terminals 55, 55 connected to the pair of bobbins 50, 50 are provided at both ends of the electrofusion joint 40, respectively.
Indicator portions 42, 42 are provided so as to be exposed on the outer peripheral surface.

Hereinafter, an example of a method for manufacturing the electrofusion joint 40 shown in FIG. 8 will be described with reference to FIGS. First, as shown in FIG. 9A, on the core 71,
The resin-coated heating wire 52 is spirally wound so that the core 71 is rotated in the circumferential direction, and the pair of windings 50 ′, 50 ′ are connected by the connecting resin-coated heating wire 53.
Is formed, and the space between the resin-coated heating wires 52 adjacent to the windings 50 ′, 50 ′ is fixed by an iron stop 54.

Next, as shown in FIG. 9B, the resin-coated heating wires 52, 52 at both ends of the pair of windings 50 ', 50'.
The metal wire is exposed by peeling off the resin coating layer at the end of the pair, and terminal pins 55, 55 are connected to the metal wire to form a pair of bobbins 50, 5 made of a spirally wound resin-coated heating wire.
Get 0. A stretched polyethylene sheet is wound around the bobbins 50, 50 so as to straddle both bobbins 50, 50, and a tubular body 60 made of the stretched polyethylene sheet is laminated. At this time, since the core 71 is used as the inner mold of the injection mold, it is left attached.

Next, as shown in FIG.
Then, the handle 72 is fixed so that the support portions 721 and 721 are connected to both ends thereof. At both ends of the handle 72, terminal pin fixing portions 722, 722 extending toward both the pobins 50, 50, and indicator pins 117, 1
17 are provided. Terminal pin fixing part 72
2, 722 are fixed by inserting the upper ends of the terminal pins 55, 55, and are prevented from being covered with a thermoplastic resin at the time of injection molding around the upper ends. Indicator pins 117, 117
Is provided with a hole into which a thermoplastic resin enters during injection molding for forming the indicator portion.

Next, as shown in FIG. 10, the core 71 to which the handle 72 is fixed is attached to the outer mold 73 of the injection mold 70.
Inserted into the mold, clamped, and the injection mold 70
After performing a series of injection molding in which a thermoplastic resin is injected into the mold, the mold is opened, and the core 71 is removed, the handle 72 is removed to form a polyethylene formed by injection molding as shown in FIG. In the wall 41, a pair of bobbins 50, 50 made of a spirally wound winding of the resin-coated heating wire 52 are embedded over a predetermined length.
An electro-fusion joint 40 is obtained in which a tubular body 60 made of a roll of a stretched polyethylene sheet is embedded in a polyethylene wall 41 outside thereof so as to straddle 0, 50. A pair of bobbins 50, 5 are provided at both ends of the electric fusion joint 40.
Terminal pins 55, 55 connected to 0 and indicator portions 42, 42 are provided so as to be exposed on the outer peripheral surface.

Since the electrofusion joint 40 is reinforced by a tubular body 60 made of a roll of a stretched polyethylene sheet, it has excellent internal pressure resistance, and is similar to that shown in FIG. When a conduit is formed by using the composite pipes as joints for connecting by electric fusion, there is no possibility of breakage even if a fluid flows at a high pressure in the conduit. In addition, since the layer of the polyethylene wall 41 exists on the cylindrical body 40, the cylindrical body 40 is protected from external force, and there is no possibility that the cylindrical body 40 is damaged or damaged by external force.

[0041]

According to the electrofusion joint of the present invention having the above-described structure, composite pipes having excellent internal pressure resistance are joined to each other by a simple operation in a state having excellent internal pressure resistance. can do.

Since the method for manufacturing an electro-fusion joint of the present invention has the above-described structure, an electro-fusion joint having excellent internal pressure resistance can be manufactured by simple operations.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one example of an electrofusion joint of the present invention.

FIG. 2 is a front view illustrating a first half of a step of forming a pair of bobbins in an example of the method for manufacturing an electro-fusion joint according to the present invention.

FIG. 3 is a front view illustrating the latter half of the step of forming a pair of bobbins in an example of the method for manufacturing an electro-fusion joint according to the present invention.

FIG. 4 is a partial cross-sectional view illustrating a step of mounting a pair of bobbins in a composite pipe in an example of the method for manufacturing an electrofusion joint of the present invention.

FIG. 5 is a cross-sectional view illustrating a step of inserting a composite pipe and a pair of bobbins into an outer mold in an example of the method for manufacturing an electrofusion joint of the present invention.

FIG. 6 is a cross-sectional view illustrating an injection molding step in an example of the method for manufacturing an electro-fusion joint of the present invention.

FIG. 7 is a perspective view showing an example of a composite pipe used in an example of the electrofusion joint and the method of manufacturing the same according to the present invention.

FIG. 8 is a partial sectional view showing another example of the electrofusion joint of the present invention.

FIGS. 9A and 9B are explanatory views of the steps in the method for manufacturing an electro-fusion joint according to the present invention, wherein FIG. 9A is a front view illustrating the first half of a step of forming a pair of bobbins, and FIG. FIG. 7C is a front view illustrating a process of connecting a handle to a core, and FIG.

FIG. 10 shows a method for manufacturing an electro-fusion joint of the present invention.
It is sectional drawing explaining an injection molding process.

[Explanation of symbols]

 10, 40 electrofusion joint 10A, 40A socket 11 composite pipe 111 inner layer 60, 121 cylindrical body 123 outer layer 12 injection molded layer 20, 50 bobbin 22, 52 heating wire 41 thermoplastic resin wall 30, 70 injection mold 31 Inner mold 32,73 Outer mold 71 Core

Claims (4)

[Claims] 1. An electrofusion device comprising a plurality of receiving ports provided at both ends, and a bobbin comprising a helical winding of a heating wire embedded in a thermoplastic resin wall forming the receiving ports over a predetermined length. A wearing joint, wherein a tubular body made of a roll of a stretched thermoplastic resin sheet is embedded in a thermoplastic resin wall outside the bobbin so as to straddle both bobbins. Electric fusion joint. 2. A portion in which the tubular body is embedded has a composite pipe structure in which a tubular body made of a roll of a stretched thermoplastic resin sheet is laminated between inner and outer layers formed of a thermoplastic resin. The electrofusion joint according to claim 1, wherein: 3. A step of spirally winding a heating wire to form a pair of bobbins connected in series, and connecting the pair of bobbins between inner and outer layers formed by a thermoplastic resin. A step of mounting the tubular body made of the wound material in the laminated composite pipe, inserting the same into an injection mold, and injecting a thermoplastic resin into the injection mold. A method for producing an electric fusion joint. 4. A step of spirally winding a heating wire to form a pair of bobbins connected in series, and winding a stretched thermoplastic resin sheet outside the pair of bobbins so as to straddle the pair of pobbins. Forming a cylindrical body by turning, inserting the pair of bobbins and the cylindrical body into an injection mold, and injecting a thermoplastic resin into the injection mold. Method for producing an electric fusion joint.