JPH079559A - Manufacture of electric fusion-bonding plastic tube joint - Google Patents

Abstract

PURPOSE:To easily obtain a large bore tube joint by preparing two elements obtained by inserting a mandrel of one heating member into a faucet of a pipe obtained by winding it with a coated electric heating wire, then energizing it to fusion-bond it to form an electric fusion-bonded connecting member, and then removing the mandrel, and heating to melt end faces having no faucet. CONSTITUTION:An electric heating wire 3 coated with thermoplastic resin material is densely wound on a mandrel 4 as a heating member 30, the mandrel 4 is inserted into a faucet 121 of a thermoplastic pipe 1, the wire 3 is energized to heat the member 30, resin in which an inner surface of the faucet 121 is brought into contact with the member 30 is fusion-bonded and integrally mounted. After the fusion-bonded part is cooled, only the mandrel 4 is drawn to form an electric fusion-bonded connecting member 1A containing the member 30. Entirely the same electric fusion-bonded connecting member 2A as the member 1A is prepared. ends 15, 25 of the sides having no faucet are heated, and press-bonded to be connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric fusion type plastic pipe joint in which a plastic pipe to be connected has a relatively large nominal diameter.

[0002]

2. Description of the Related Art As a conventional method for manufacturing an electric fusion type plastic pipe joint (hereinafter sometimes simply referred to as a pipe joint), Japanese Patent Publication No. 1-45410 discloses a thermoplastic resin having a thread groove on its outer surface. Disclosed is a method for manufacturing an electric fusion-bonded plastic pipe joint by injection-molding an inner cylinder member, winding a heating wire around a screw groove, and then integrally injection-molding an outer cylinder member on the outside of the inner cylinder member. Has been done.

In Japanese Patent Publication No. 61-41293, a pipe obtained by injection molding or extrusion molding is heated and maintained at a temperature below the remelting temperature, while a heating wire coated with a thermoplastic resin is wound on a diameter-expanding mandrel. And the inner surface of the heated pipe is expanded by the expanding mandrel to press-fit the threaded coil, so that the threaded coil is attached to the inner surface of the pipe. A method of manufacturing a pipe joint is disclosed.

In Japanese Patent Laid-Open No. 63-71323, heating wires are wound around a mandrel in advance, connector pins are connected to the mandrel, a mold is set on the outside of the mandrel, and an outer cylinder body is injection-molded on the mold. Then, a mandrel is pulled out after that, and as a result, a method for producing an electric fusion type plastic pipe joint containing a heating wire is disclosed.

[0005]

Each of the above manufacturing methods has merits and demerits, but the problem here is to manufacture a large-diameter pipe joint having a nominal diameter of, for example, 150 mm or more to be connected. This is a problem when doing. That is, all of the above manufacturing methods require an injection molding machine or a heating / press-fitting device. If a large size of 150 mm or more is to be injection molded, it is necessary to have a high injection pressure of the injection molding machine itself and a high mold clamping force, and the existing equipment such as an injection molding machine for small diameters is diverted. I can't do it. Therefore, a new large-capacity injection molding machine and a mold are required, and the investment amount becomes large.

The present invention solves such a problem, and provides a method capable of easily and inexpensively producing a large-diameter electrofusion-type plastic pipe joint without using an injection molding machine. To aim.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a method for producing an electric fusion type plastic pipe joint comprising a pipe made of a thermoplastic resin and a heating wire coated with the thermoplastic resin.
A step of forming an inner surface of one end of the pipe in a receiving portion for receiving the coated heating wire; a step of closely winding the coated heating wire around a mandrel to form one heating member; and a mandrel including the heating member A step of inserting the pipe into the receiving portion of the pipe, a step of energizing the heating wire to fuse the heating member to the inner surface of the pipe receiving portion to form the electric fusion connecting member,
A step of removing the mandrel after the fused portion is cooled, a step of preparing two of the above-mentioned electric fusion connecting members, heating and melting the end faces of the electric fusion connecting members which are not the receiving portions, and crimping and joining them. Is an electric fusion type plastic pipe joint.

Further, in the above, a heating sheet obtained by printing a conductive metal on a thermoplastic sheet material is used in place of the coated heating wire, and this is attached to the inner surface of the receiving portion by fusion bonding in the same manner as described above. Type plastic pipe joints may be used. Further, although the above-mentioned pipe joint is intended for a socket type, for example, if the electric fusion-bonding member is heated and pressure-bonded to the T-shaped or L-shaped intermediate member via an intermediate member, an elbow-shaped or Q-shaped electric joint, respectively. A fusion type plastic pipe joint can be obtained.

[0009]

According to the above electric fusion type plastic pipe joint, the joint main body portion is a commercially available pipe (for example, a polyethylene pipe) obtained by extrusion molding or the like, which is used as it is, and an additional process is appropriately performed. Can be manufactured easily and inexpensively. Further, as the heating member which is another element, a known member such as a resin-coated heating wire or a resin sheet on which a conductive metal is printed by printing is used as a single body, but here, by utilizing the fact that the member itself can generate heat and melt, The pipe is inserted and arranged on the inner surface of the receiving port via a mandrel or the like, and then electrically heated to be fused and attached integrally to the inner surface of the receiving port. As described above, it is possible to obtain an electric fusion type connection member having a heating means built therein. Next, butt joining is performed according to the type of pipe joint that requires this connecting member. That is, in the case of a socket, the end faces of the connection member that are not the receiving ports are thermocompression bonded (bad fusion). When an elbow or a chi is required, a connecting member may be similarly thermocompression bonded to the L-shaped and T-shaped intermediate members via the intermediate members. As described above, the electrofusion-type plastic pipe joint can be easily and inexpensively manufactured without using an injection molding machine or the like. It is especially convenient for pipes with a nominal diameter of 150 mm or more that are difficult to make, such as pipe joints.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, which is an example of using a coated heating wire as a heating member. The approximate manufacturing process is shown in (A) to (E). (A) of FIG. 1 (hereinafter referred to as 1- (A), (B) ...) is a thermoplastic pipe that will later become the main body of the electric fusion type plastic pipe joint,
A commercially available polyethylene pipe is used here. 1
Although 2 and 13 are through holes, this diameter may be machined as necessary to match the outer diameter of the polyethylene pipe to be connected. In 1- (B), one end 14 side of the pipe 1 is additionally processed to have a diameter such that a heating member composed of a coated heating wire, which will be described later, is fitted to form a receiving portion 121 of a polyethylene pipe. is there. 1- (C) shows a state in which the heating wire 3 coated with the thermoplastic resin material is tightly wound around the mandrel 4 to form one heating member 30. Here, it is preferable that the heating wire 3 is wound in two strands so that both ends of the heating wire can be taken out from one end located outside the pipe as shown in the figure through an insulating material.

1- (D) inserts the mandrel 4 as it is into the receiving portion 121 of the pipe, and in that state, the heating wire 3
Is energized to heat the heating member 30, the inner surface of the receiving portion 121 and the resin portion where the heating member 30 contacts each other are melted and fused, and the heating member 30 is transferred to the inner surface of the receiving portion 121 of the pipe 1. Install integrally. After that, when the fused portion is cooled, only the mandrel 4 is pulled out and removed. By the above, heating member 30
The electro-fusion-bonding member 1A containing the is molded. Next, 1- (E) is the electrofusion-bonding member 1 obtained above.
A and the same electric fusion splicing member 2A as this are prepared,
The end faces of the respective non-receptive portions, that is, the end faces 15 and 25 are heated by a heating plate or the like to be in a molten state and then pressure-bonded to each other (butt fusion). Socket-type electric fusion type plastic pipe fitting 10
Is completed. Reference numeral 6 in the drawing denotes a recessed hole for an indicator, which may be machined as required.

When joining the electro-fusion type plastic pipe joint and the polyethylene pipe, after inserting the polyethylene pipe into one of the receiving portions, an external controller and a heating wire are connected to energize each nominal size. After deciding the time and the like, the two are fusion-bonded by heating by energization. After that, fusion bonding is similarly performed on the other receiving portion.

FIG. 2 shows another embodiment of the present invention, in which a heating sheet is used as the heating member. The approximate manufacturing process is shown in (A) to (D).
Since the subsequent process of (D) is the same as that of (E) of FIG. 1, it is omitted. The same parts as those in FIG. 1 are designated by the same reference numerals. Therefore, the only difference from FIG. 1 is that the heating member shown in (C ′) is used. As shown in (C '), a heating member is obtained by printing a conductive metal 8 on a thin film sheet made of a thermoplastic resin. Although various printed patterns of the conductive metal 8 can be considered, both ends thereof are provided in parallel toward the outside of the pipe.

Although all of the above examples are socket type pipe joints, when an elbow or a chi is required, the above-mentioned electric fusion splicing member is attached to an intermediate member made of L type or T type thermoplastic resin. Each can be appropriately manufactured by thermocompression bonding.

[0015]

According to the present invention, it is possible to obtain an electric fusion splicing member in which a heating member such as a coated heating wire is integrally mounted on the inner surface of a pipe without using an injection molding machine.
Then, if the electric fusion-bonding members are joined by thermocompression bonding through the intermediate member, the electrofusion-type plastic pipe joint can be easily manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a drawing for explaining the manufacturing process of the embodiment of the present invention.

FIG. 2 is another embodiment of the present invention, which is also a drawing for explaining the manufacturing process thereof.

[Explanation of symbols]

 1, 2 ... Polyethylene pipe 1A, 2A ... Electric fusion splicing member 3 ... Heating wire coated with thermoplastic resin 4 ... Mandrel 5 ... Thermocompression bonding part 6 ... Indicator hole 7 ... Thermoplastic resin heating sheet 10 ... Electricity Fusion-bonded plastic pipe fittings 12, 13 ... Pipe receiving part 14, 24 ... Receiving side end face 15, 25 ... Crimping joining side end face 30 ... Heating member

Claims (3)

[Claims] 1. A method of manufacturing an electrofusion-type plastic pipe joint comprising a thermoplastic resin pipe and a heating wire coated with the thermoplastic resin, wherein an inner surface of one end of the pipe receives the coating heating wire. Forming a receiving portion, forming a single heating member by closely winding the coated heating wire around a mandrel, inserting a mandrel including the heating member into the receiving portion of the pipe, The process of energizing the heating wire and fusing the heating member to the inner surface of the pipe receiving part to form the electric fusion splicing member, the process of removing the mandrel after the fused part is cooled, and the electric fusion obtained by the above Two of the fusion-splicing members are prepared, and the end faces of these electro-fusion-bonding members that are not the receiving portion are heated and melted, and they are pressure-bonded to each other to form an electro-fusion-type plastic pipe joint. And a method for manufacturing an electric fusion type plastic pipe joint. 2. A method for producing an electric fusion-bonding type plastic pipe joint comprising a thermoplastic resin pipe and a heating sheet formed by printing a conductive metal on a thermoplastic resin sheet, the pipe comprising: A step of forming an inner surface of one end into a receiving portion for receiving the heating sheet, a step of winding the heating sheet around a mandrel, a step of inserting a mandrel including the heating sheet into the receiving portion of the pipe, and the conductivity. The process of energizing the metal to fuse the heating sheet to the pipe receiving part to form the electric fusion splicing member, the process of removing the mandrel after the fused portion is cooled, and the electric fusion splicing obtained as above Two members are prepared, and the end faces of the electric fusion-bonding members that are not the receiving portions are heated and melted, and they are pressure-bonded to each other to form an electrofusion-type plastic pipe joint. A method for producing an electric fusion-bonded plastic pipe joint, which is characterized in that: 3. A plurality of the electric fusion splicing members are prepared,
The method for producing an electrofusion-type plastic pipe joint according to claim 1 or 2, wherein the electrofusion-bonding members are thermocompression-bonded to each other via an intermediate member made of a thermoplastic resin.