JPH07253186A - Tube fitting containing heating wire and its manufacture - Google Patents

Abstract

PURPOSE:To provide a tube fitting containing heating wires which are hardly short-circuited, even though the tube fitting is heated. CONSTITUTION:In this tube fitting containing heating wires, numerous nonconductive heating wire isolating members 4 which maintain the separating condition of neighboring heating wires 2, and consist of a high softening temperature material whose softening temperature is higher than that of a thermal plastic resin are buried in the condition placing between the neighboring heating wires 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a joint body from a thermoplastic resin that can be heat-sealed to a pipe made of a thermoplastic resin, and an electric wire is provided near the surface of the joint body facing the pipe. The present invention relates to a heating wire-equipped pipe joint formed by embedding heat wires in a plurality of rows arranged in parallel at intervals along the facing surface to form a heat-sealed portion, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Heretofore, a pipe fitting with a heating wire of this kind has been constructed in such a manner that the heating wire is simply buried in a plurality of rows arranged in parallel with each other at intervals along the facing surface, and is usually a medium-sized pipe. The heating wire was wound around the joint, and the thermoplastic resin was introduced into the accommodation space between the middle mold, the outer mold, and the outer mold for molding the joint body to form the joint body.

[0003]

According to the above-mentioned conventional pipe joint with heating wire, if the pipe is closely adhered to the heat-sealed portion while the pipe is opposed and a current is passed through the heating wire, the vicinity of the heating wire is Although the thermoplastic resin of the heat fusion part is melted, adheres to the opposing pipe, and then is cooled, the pipe is fusion-bonded to the pipe joint, but the heating wire When the nearby thermoplastic resin is in a molten state, the heating wire becomes movable and heat-expands due to heating, so that the embedded position of the heating wire moves and adjacent heating wires come into contact with each other. The heating wire may be short-circuited and the melting efficiency for melting the thermoplastic resin may be lowered, and the heat fusion performance may be reduced, and a pipe fitting with a heating wire that is more reliable in heat fusion is desired. Was there. Further, such a phenomenon is considered to be more prominent in the case where the heating wire has a "bent gusset", and was considered to be a cause of defective fusion. Furthermore, when molding such a pipe joint, a thermoplastic resin is poured into the mold to mold it, but when the thermoplastic resin is poured into the mold, the heating wire to be fixed in the mold is It has also been considered that the flow of the thermoplastic resin causes pressure to deform and short circuit.

Therefore, in view of the above-mentioned drawbacks, an object of the present invention is to provide a heating wire-containing pipe joint in which heating wires are less likely to be short-circuited even when heated.

[0005]

The characteristic constitution of the first invention for attaining this object is to provide a large number of materials having a softening temperature higher than that of the thermoplastic resin for maintaining the separated state of adjacent heating wires. The heating wire isolation member is embedded in a state of being interposed between the adjacent heating wires. Further, the characteristic means of the second invention is to prepare a columnar middle die and an outer die for molding a joint body for forming a housing space for the thermoplastic resin on the outer side of the middle die, and forming a thermoplastic resin layer on the outer peripheral portion. The heating wire is wound in a spiral shape in the middle size, and is attached in a state where the heating wire separating member is inserted between the adjacent heating wires, and in that state, in the accommodation space, on the outer peripheral portion of the heating wire. A thermoplastic resin of the same type as that of the formed thermoplastic resin layer is introduced to mold the joint body. The characteristic means of the third invention is that a T-shaped middle mold and a thermoplastic resin on the outside of the middle mold. An outer die for molding a T-shaped joint body that forms a resin accommodation space is prepared, and a heating wire having a thermoplastic resin layer formed on the outer peripheral portion is spirally arranged around the branch portion of the middle die. In addition, the heating wire isolation member is inserted between the adjacent heating wires. The mounting, in the accommodation space in that state, by introducing a thermoplastic resin of the thermoplastic resin layer and the same kind formed on the outer peripheral portion of the heating wire is to molding the coupling body. These actions and effects are as follows.

[0006]

That is, according to the structure of the first invention, even if the heating wire is heated and melts the surrounding thermoplastic resin, the heating wire separating member is positioned between the heating wires without melting. , Even if the heating wire is thermally expanded, the heating wire is not in contact with each other by the heating wire isolation member,
There is no short circuit.

At this time, in forming the heating wire separating member, a shaft portion is provided in the heat fusion portion along the juxtaposed direction of the heating wires, and a large number of protrusions that can respectively penetrate between the adjacent heating wires. If the shaft portion is connected to the shaft portion, the protrusions can be easily inserted between the heating wires only by arranging the heating wires in parallel and then mounting the shaft portion along the parallel direction of the heating wires. It is possible to do so, and even if the heating wire contacts the heating wire separating member, it is difficult for the heating wire separating member to move and the heating wires easily come into contact with each other. If the fence member extending along the heating wire is formed, it is possible to reliably prevent adjacent heating wires from contacting each other in the longitudinal direction of the heating wire.

Further, if a shaft member is provided along the direction in which the tube is arranged with respect to the heat fusion portion and a plurality of barrier members are provided along the heating wire to form the heating wire separating member, After arranging the heating wires in parallel, by simply attaching the shaft portion along the arranging direction of the heating wires, the projections can easily be inserted between the heating wires, and at the same time, surely in the longitudinal direction of the heating wires. It is possible to prevent contact between adjacent heating wires.

Further, if a coating layer around the heating wire is formed to form the heating wire isolation member, the heating wire is simply buried in the heat-sealed portion, and the heating wire is electrically connected between the heating wires. It can be arranged such that the heat ray isolating member is located.

If the shaft portion is arranged on the side opposite to the facing surface in the wall thickness direction of the joint body with respect to the heating wire, the thermoplastic resin in the vicinity of the heating wire is melted. In addition to melting the opposing thermoplastic resin pipes and performing heat fusion, the heat generated from the heating wire is easily transferred to the thermoplastic resin pipes, and the fusion performance can be maintained at a high level. There is less a risk that the shaft portion will enter the surface facing to and reduce the heat fusion performance.

In the above structure, if the thermoplastic resin is low-density polyethylene and the heating wire separating member is made of polyimide, the heat fusion property is high, and the polyethylene is melted by heating the heating wire. However, the polyimide is not melted, the heating wires can be surely prevented from contacting with each other, and the polyethylene and the polyimide are less likely to be peeled off from each other, so that the situation of impairing the airtightness is unlikely to occur.

Further, according to the structure of the second invention or the third invention, the heating wires are surely arranged in a plurality of rows in the heat-sealing portion at intervals along the surface facing the tube. While being buried in the state, since the heating wire separating member is arranged between the adjacent heating wires, the manufactured heating wire-equipped pipe joint has the function of the configuration of the first invention. In addition to being able to reliably exhibit, since the heating wire is formed with a thermoplastic resin layer made of the same kind of thermoplastic resin as the joint body, when winding the heating wire around the middle size, Adjacent heat wires cannot contact each other, and even if the thermoplastic resin is poured into the mold, it is possible to obtain a state in which the heat wires are arranged side by side with certain intervals.

Further, if the surface of the heating wire isolation member is coated with the thermoplastic resin in advance, the heating wire isolation member will be attached to the pipe when the heating wire isolation member is interposed between the heating wires. It is rarely exposed on the facing surface and impairs the fusion performance between the pipe and the joint body.

[0014]

Therefore, the heating wires do not touch each other,
Since there is no short circuit, the tube and the heat-sealed portion can be reliably heat-sealed. As a result, even if the connecting pipe is a gas pipe, it can be connected with high airtightness and can be used with high reliability.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pipe fitting with a heating wire of the present invention (hereinafter simply referred to as pipe fitting) will be described below with reference to the drawings.

[Straight pipe type pipe joint] As shown in FIGS.
A tubular joint body 1 is formed from low-density polyethylene, and a heating wire 2 made of nichrome is spirally embedded near the inner surface of the joint body 1 facing the pipe P to form a heat-sealing portion 3. A comb-shaped heating wire separating member 4 made of polyimide is embedded in a state of being interposed between the adjacent heating wires 2.

As shown in FIG. 3, the heating wire separating member 4 is provided with a plurality of protrusions 4b in a comb shape on a shaft portion 4a along the longitudinal direction of the joint body 1, and the respective protrusions 4b are arranged in the plurality of rows. Will be installed side by side.

Further, connecting terminals 5 for supplying a current to the heating wire 2 are provided on the joint body 1 at both ends of the heating wire 2, and a current is passed from the outside of the joint body 1 to the heating wire 2 to generate heat. It is freely configured.

The pipe joint is manufactured as shown in FIG. (1) First, the heating wire 2 and the heating wire isolation member 4 are coated with the low density polyethylene. (2) The heating wire 2 is wound around the outer periphery of the middle mold 6 for molding the joint body 1. (3) A plurality of heating wire separating members 4 are attached to the middle mold 6 from the outer side of the heating wire 2 so that the protrusions 4b are located between adjacent wound heating wires 2 (Fig. 3 ( B)). (4) The middle mold 6 is covered with the outer mold 7, low-density polyethylene in a molten state is injected into the accommodation space 8 between the middle mold 6 and the outer mold 7, and the mixture is cooled and solidified to mold the joint body 1 ( See FIG. 3B). At this time, both ends of the heating wire 2 are
The connection terminal 5 is formed so as to be connectable.

In the pipe joint manufactured in this manner, the projection 4b is provided between the heating wires 2, and
The heating wires 2 and the heating wire separating member 4 are integrally formed in a state in which the heating wires 2 and the heating wire separating member 4 are buried without being exposed on the surface facing the pipe P, while being arranged side by side.

When the pipe ends are connected to each other using such a pipe joint, the following process is performed. (1) First, the skin of the pipe ends to be connected is scraped off using a plane or the like. (2) The pipe ends are attached to the pipe joint so as to abut each other in the joint body 1. At this time, the heat-sealed portion 3 of the joint body 1 and the outer surface of the pipe end face each other in a state of being in close contact with each other. (3) A connection terminal 5 is attached to the joint body 1, the connection terminal 5 is connected to a power source, and an electric current is passed through the heating wire 2 to generate heat. (4) When the low-density polyethylene of the heat-sealed portion 3 of the joint body 1 and the thermoplastic resin of the pipe end portion (preferably made of low-density polyethylene of the same material as the joint body 1) are melted by the heat generated by the heating wire 2. , The ends of both pipes are fused with the joint body 1,
The pipe ends can be connected and connected.

Therefore, the pipe ends are densely filled with the melted thermoplastic resin, that is, they are connected to each other so that a high airtight state can be maintained.

[Saddle Type Pipe Joint] As shown in FIGS. 4 and 5, a T-shaped joint body 1 is formed from low density polyethylene, and a heating wire 2 made of nichrome is provided near the inside of the surface facing the pipe P. The heat-sealing portion 3 is formed by being embedded in a spiral shape, and a comb-shaped heating wire separating member 4 made of polyimide is embedded in a state of being interposed between the adjacent heating wires 2.

The heating wire separating member 4 is formed by providing a number of protrusions 4b in a comb shape on a shaft portion 4a along the longitudinal direction of the joint body 1 and arranging the respective protrusions 4b in parallel in the plurality of rows.

Further, connection terminals 5 for supplying current to the heating wire 2 are provided on the joint body 1 at both ends of the heating wire 2, and a current is passed from outside the joint body 1 to the heating wire 2 to generate heat. It is freely configured.

The pipe joint is manufactured as follows. (1) First, the heating wire 2 and the heating wire isolation member 4 are coated with the low density polyethylene. (2) The heating wire 2 is wound around the branch portion 6a of the middle mold 6 for molding the joint body 1. (3) The heating wire 2 is attached to the middle die 6 from the outer side of the heating wire 2 so that the protrusion 4b is located between the adjacent heating wires 2. (4) The middle mold 6 is covered with the outer mold 7, low-density polyethylene in a molten state is injected into the accommodation space 8 between the middle mold 6 and the outer mold 7, and the mixture is cooled and solidified to mold the joint body 1.
At this time, both ends of the heating wire 2 are formed so that the connection terminals 5 can be connected.

In the pipe joint manufactured in this manner, the projection 4b is arranged between the heating wires 2,
The heating wire 2 and the heating wire separating member 4 are integrally formed in a state in which the heating wire 2 and the heating wire separating member 4 are embedded without being exposed at the surface facing the pipe P of the heat fusion portion 3 while being arranged side by side. It

When the branch pipe p can be connected to the side peripheral portion of the pipe P using such a pipe joint, it is carried out as follows. (1) First, the skin of the portion of the pipe P to be connected is scraped off using a plane or the like. (2) The heat-sealed portion 3 of the joint body 1 is butted against the skin-cut portion of the pipe P and attached to the pipe joint. At this time, the heat-sealed portion 3 of the joint body 1 and the outer surface of the pipe P face each other in a state of being in close contact with each other. (3) A connection terminal 5 is attached to the joint body 1, the connection terminal 5 is connected to a power source, and an electric current is passed through the heating wire 2 to generate heat. (4) When the low-density polyethylene of the heat-sealing portion 3 of the joint body 1 and the thermoplastic resin of the pipe P are melted by the heat generated by the heating wire 2, the pipe P is fused with the joint body 1 and the side wall of the pipe P is formed. It is possible to form the connecting portion 1a for connecting the branch pipe p.

Therefore, the pipe P and the pipe joint are tightly filled with the molten thermoplastic resin, that is, the pipe joint can be fixed to the outer peripheral surface of the pipe P, so that the branch pipe p can be connected to the pipe P freely. become.

[Other Embodiments] In the previous embodiment, the heating wire separating member 4 is formed in a comb shape, but it may be formed in a rail shape or a cover layer shape. An example in which those heating wire isolation members 4 are applied to a straight pipe type pipe joint will be shown below.

[Rail Type Heating Wire Separating Member] <1> As shown in FIG. 6, a large number of semicircular fence members 4c are formed on the shaft portion 4a along the longitudinal direction of the joint body 1 in plan view. 4a and the fence member 4c intersect each other, the rail members 4c are provided in a rail shape that forms a gap between the fence members 4c, and the fence members 4c are arranged in parallel in the plurality of rows to form the heating wire separating member 4. To do.

When a pipe joint is manufactured using this heating wire separating member 4, it is carried out as follows. (1) First, the heating wire 2 and the heating wire isolation member 4 are coated with the low density polyethylene. (2) The heating wire 2 is wound around the outer periphery of the middle mold 6 for molding the joint body 1. (3) From the direction in which the heating wire separating member 4 is opposed to the middle mold 6 from the outer side of the heating wire 2 so that the fence member 4c is located between adjacent ones of the wound heating wires 2. Install two. (4) The middle mold 6 is covered with the outer mold 7, low-density polyethylene in a molten state is injected into the accommodation space 8 between the middle mold 6 and the outer mold 7, and the mixture is cooled and solidified to mold the joint body 1.

<2> As shown in FIG. 7, a strip-shaped fence member 4c along the heating wire 2 is spirally formed in the joint body 1.
The heating wire isolation member 4 is configured.

When a pipe joint is manufactured using this heating wire separating member 4, it is carried out as follows. (1) First, the heating wire 2 and the fence member 4c are coated with the low density polyethylene. (2) The fence member 4c is wound around the outer periphery of the middle mold 6 for molding the joint body 1. At this time, the fence member 4c
A rail-shaped gap is formed in the winding direction. (3) Wind it so that the heating wire 2 is located in the gap. (4) The middle mold 6 is covered with the outer mold 7, low-density polyethylene in a molten state is injected into the accommodation space 8 between the middle mold 6 and the outer mold 7, and the mixture is cooled and solidified to mold the joint body 1.

According to the above rail type structure, the heating wire 2
However, the heating wire separating member 4 is separated over substantially the entire length, and the heating wire 2 can be reliably prevented from being short-circuited even in a heated state.

[Coating Layer Type Heating Wire Separating Member] As shown in FIG. 8, a coating layer 4d made of polyimide is formed on the heating wire 2,
The heating wire separating member 4 is formed with the coating layer 4d.

When a pipe joint is manufactured using this heating wire separating member 4, it is carried out as follows. (1) First, the heating wire separating member 4 integrated with the heating wire 2 is coated with the low density polyethylene. (2) Heating wire separating member 4 integrated with the heating wire 2
Is wound around the outer circumference of the middle mold 6 for molding the joint body 1. (3) The middle mold 6 is covered with the outer mold 7, low-density polyethylene in a molten state is injected into the accommodation space 8 between the middle mold 6 and the outer mold 7, and the mixture main body 1 is molded by cooling and solidifying.

According to the above-mentioned coating layer type structure, the heating wire separating member 4 reliably maintains the state where the heating wires 2 are isolated from each other, so that the heating wires 2 can be reliably prevented from being short-circuited even in the heated state.

[Modification] In any of the above embodiments, the heating wire separating member 4 is made of polyimide, the thermoplastic resin is made of low density polyethylene, and the heating wire 2 is made of nichrome, but the material is not limited to these. , For example, the heating wire isolation member 4
May be made of polyethylene terephthalate, and the thermoplastic resin may be plasticized polyvinyl chloride. According to the above-mentioned constitution, the softening temperatures of the heating wire separating member 4 and the thermoplastic resin are 220 ° C. and 75 ° C., respectively. According to the configuration described later, since the heating wire 2 is heated to 150 ° C. and 60 ° C., the thermoplastic resin is melted by heating the heating wire 2, and the heating wire separating member 4 is not melted easily, and the fusion bonding is achieved. It becomes easy and it is possible to prevent the heating wires 2 from coming into contact with each other and being short-circuited even when the heating wires 2 deform. Needless to say, the heating wire 2 may be any metal or alloy having a large electric resistance.

When the heating wire 2 or the heating wire isolation member 4 is wound around the middle die 6, the outer surface of the heating wire 2 is coated with a thermoplastic resin in advance, but it is not always necessary.
It is preferable that the middle mold 6 and the heating wire 2 or the heating wire separating member 4 be spaced apart from each other and fixed in the accommodation space. However, the heating wire 2 is wound around the middle mold 6 as it is to form the joint body 1. You may resin-mold.

It goes without saying that the rail type or coating layer type heating wire isolation member 4 shown above can be applied to a saddle type pipe joint.

Further, the comb-shaped or rail-shaped heating wire separating member 4 is provided.
May be provided in any number in the direction in which the heating wires 2 are arranged in parallel, for example, a heating wire in which a rail-type heating wire isolation member 4 is spirally wound using a one-third circular fence member 4c. Two heating wires 2 may be provided in the outer peripheral portion of the heat-sealing portion 3 to keep the heating wires 2 in an isolated state over the entire circumference of the heat-sealing portion 3.

In the claims, reference numerals are given 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 vertical sectional side view of a straight pipe type pipe joint.

FIG. 2 is a cross-sectional side view of a straight pipe type pipe joint.

[Fig. 3] Manufacturing process drawing of straight pipe type pipe joint

FIG. 4 is a vertical sectional side view of a saddle type pipe joint.

FIG. 5 is a transverse side view of a saddle type pipe joint.

FIG. 6 is a manufacturing process diagram of a pipe fitting with heating wire in another embodiment.

FIG. 7 is a manufacturing process diagram of a pipe fitting with heating wire according to another embodiment.

FIG. 8 is a manufacturing process diagram of a pipe fitting with heating wire according to another embodiment.

[Explanation of symbols]

 P pipe 1 Joint body 2 Heating wire 3 Heat fusion part 4 Heating wire isolation member 4a Shaft part 4b Protrusion 4c Fence member 4d Cover layer 6 Medium size 7 Outer frame 8 Storage space

Claims (10)

[Claims] 1. A joint body (1) is formed from a thermoplastic resin that can be heat-sealed to a pipe (P) made of a thermoplastic resin, and the joint body (1) faces the pipe (P). A heating-wire-equipped pipe joint in which a heating wire (2) is buried near a surface in a plurality of rows in parallel at intervals along the facing surface to form a heat-sealed portion (3). Therefore, a large number of non-conductive heating wire separating members (4) made of a material having a softening temperature higher than that of the thermoplastic resin are maintained for the adjacent heating wires (2) while keeping the adjacent heating wires (2) separated from each other. A pipe fitting with a heating wire embedded so as to be interposed between the heating wires (2). 2. A shaft portion (4a) is provided in the heat fusion portion (3) along the juxtaposed direction of the heating wire (2), and a large number of pieces can be inserted between adjacent heating wires (2). The heating-wire-included pipe joint according to claim 1, wherein a projection (4b) is continuously provided on the shaft portion (4a) to form the heating-wire isolation member (4). 3. The heating wire separating member (4) is formed by forming a fence member (4c) extending along the heating wire (2) between the adjacent heating wires (2). The pipe fitting with a heating wire according to 1. 4. The heating wire (2) is provided with a shaft portion (4a) provided along the arrangement direction of the pipe (P) with respect to the heat fusion portion (3).
The heating wire-containing pipe joint according to claim 1 or 3, wherein a plurality of fence members (4c) are provided along the heating wire to form the heating wire isolation member (4). 5. The pipe fitting with heating wire according to any one of claims 1 to 4, wherein the heating wire separating member (4) comprises a coating layer (4d) formed around the heating wire (2). 6. The shaft portion (4a) is arranged on the side opposite to the facing surface in the wall pressure direction of the joint body (1) with respect to the heating wire (2). A pipe fitting with a heating wire according to any one of 1. 7. The pipe fitting with heating wire according to claim 1, wherein the thermoplastic resin is low-density polyethylene, and the heating wire (2) and the heating wire separating member (4) are made of polyimide. . 8. The method for manufacturing a pipe fitting with a heating wire according to claim 1, wherein the column-shaped middle mold (6) and a thermoplastic resin accommodating space outside the middle mold (6). An outer mold (7) for molding a joint body forming (8) is prepared, and a heating wire (2) having a thermoplastic resin layer formed on the outer peripheral portion is spirally wound around the middle mold (6). At the same time, the heating wire separating member (4) was attached between the adjacent heating wires (2) in such a state that it was formed in the accommodation space (8) at the outer peripheral portion of the heating wire (2). A method for producing a pipe joint with a heating wire, in which the same type of thermoplastic resin as the thermoplastic resin layer is introduced to mold the joint body (1). 9. A method for manufacturing a pipe fitting with a heating wire according to claim 1, comprising a T-shaped middle mold (6) and a thermoplastic resin on the outside of the middle mold (6). An outer mold (7) for molding a T-shaped joint body that forms the accommodation space (8) is prepared, and the heating wire (2) having a thermoplastic resin layer formed on the outer peripheral portion thereof is connected to the middle mold (6). The heating wire separating member (4) is arranged in a spiral shape around the branching portion, and the heating wire separating member (4) is inserted between the heating wires (2) adjacent to each other. A method for manufacturing a pipe fitting with heating wire, wherein the same type of thermoplastic resin as the thermoplastic resin layer formed on the outer peripheral portion of the heating wire (2) is introduced to mold the fitting body (1). 10. The surface of the heating wire isolation member (4) is previously coated with the thermoplastic resin before the heating wire isolation member (4) is arranged between the heating wires (2). 8. The method for manufacturing the pipe joint according to any one of 8 and 9.