JP3203770B2 - Method of manufacturing plastic electrothermal fusion joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plastic electric fusion fittings relates to a method for producing a (electric fusion joint, EF joint abbreviated below). More specifically, the present invention relates to a method of manufacturing an EF joint excellent in workability, capable of performing electrothermal fusion for each mouth, particularly suitable for connection of a large-diameter pipe or a joint having a large number of mouths.

[0002]

2. Description of the Related Art There are various methods for connecting plastic pipes, but a mechanical joint method, a heat fusion method, and an adhesive method are mainly used. The mechanical joint method is a connection method using a metal joint and is simple in construction, but lacks some reliability. The heat fusion method is a method in which the joint is made of plastic like the pipe, and the bonding surfaces (the inner surface of the joint and the outer surface of the pipe) are melted by a heater or the like before joining, and then fused. Although this method has high reliability, it has disadvantages such as a large fusing machine, difficulty in construction, skill, and a large difference in finish among individuals. The adhesive method is a method of connecting with an adhesive,
There is a problem in that it cannot be used for pipes using an olefin-based resin which is non-polar and hard to be wet by an adhesive because there is a great difference between individuals in the construction.

A joint that compensates for these disadvantages is an electrothermal fusion joint, that is, an EF joint. An EF joint is a joint having a structure in which a heating metal wire (wire) is coiled around the inner surface of the joint and embedded therein. The wire is wound around a core in a coil shape, attached to a mold, and then used with an injection molding machine. And can be manufactured by insert molding. In an EF joint, after inserting a pipe into the joint, a wire is connected to a controller that controls the amount of electricity from the power supply, and electricity is supplied to the coil on the inner surface of the joint to generate heat, thereby melting the joint surface between the joint and the pipe. Bonding is performed.

[0004] As a conventional method of connecting a controller of an EF joint to a controller, a pin serving as a plug is set on the joint body and an outlet of the controller is connected to the pin to energize, or a lead wire is taken out from the joint and connected to the controller. Has been adopted in which a lead wire is sandwiched between clips by a clip or the like.

[0005]

In the conventional EF joint,
Since the joint of each joint port is performed at once for one joint,
In the case of three or more joints, all joints could not be converted into EF joints. Further, since the large-diameter pipe is large and heavy, it is difficult to connect the joint ports at a time with a conventional EF joint.

[0006] Regarding the connection method, the method of setting up a pin on the joint is difficult when the connection with the controller is narrow, and when the outlet is disconnected immediately after energization, the plastic inside the joint is still in a molten state. In some cases, the metal wire was pulled out without being fixed, so that it was not possible to immediately proceed to the next operation after energization. On the other hand, in the method in which the lead wire is sandwiched by the clip at the connection part of the controller, the contact resistance between the clip and the lead wire is not constant, so that the pipe cannot always be fused under the same energizing condition, and the reliability of the fusion Had declined.

[0007] An object of the present invention is to be able to carry out electrothermal fusion separately for each joint port, to have a high connection reliability, and to easily construct even a narrow place or a large diameter pipe, and to connect the pipe in a short time. An object of the present invention is to provide an EF joint excellent in workability to be completed.

[0008] Another object of the present invention is to provide the above-mentioned E, which is capable of smoothly insert-molding a joint with a multi-cavity mold.
An object of the present invention is to provide a method for manufacturing an F joint.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by developing an EF joint having a structure capable of electrodeposition and fusion at each joint port of one joint. That is, the present invention is directed to the next Abstract.

[0010]

[0011]

[0012] A method of manufacturing a plastic electric fusion fitting by insert injection molding using a core and mold wound metals lines, core and mold, for each their respective joint port portion, The lead wire forming portion, the metal wire drawing portion, and the joint forming portion are provided at positions corresponding to the core and the mold in order from the end side; the outer diameter of the core is such that the joint forming portion and the lead wire forming portion have the joint diameter. The diameter corresponding to the inside diameter of the mouth and the lead-out portion are diameters when the metal wire is wound around a core substantially equivalent to the inside diameter of the joint, and a wire having the same width and depth as the metal wire diameter is provided on the core surface of the draw-out portion. Two drawing grooves are provided; the inner diameter of the mold is such that the joint forming portion has a diameter corresponding to the outer diameter of the joint port, the drawing portion has a diameter corresponding to the outer diameter of the core drawing portion, and the lead wire forming portion has a joint port. A diameter separated by a sufficient margin from a diameter of the metal wire wound around a core corresponding to the inner diameter; (A) After winding another metal wire for each joint port around the joint forming section, lead-out section, and lead wire forming section of each joint port, a core is mounted in the mold, and the core of the joint forming section and the mold characterized by injecting a resin into the gap,
Method for producing a conductive heat fusion joints.

In a preferred embodiment, the metal wire is covered with a braid of a heat-resistant insulating fiber material such as glass fiber in order to reliably prevent a short circuit during energization. Also <br/>, metal wire used for the winding-out put, it is preferable to further coat the outer circumference of a resin material of the joint body and the like. Scratch
Then, according to the present invention, the heating metal wire is embedded in the inner peripheral portion.
This is a plastic heat-sealed joint that is embedded in each joint port.
The embedded metal wire and the metal wire embedded in other joint openings
Connection is not made.
Thus, a plastic electrothermally welded joint can be obtained.
Furthermore, according to the present invention, there is provided the above-mentioned joint, wherein
Equipped with a pair of lead wires covered with drawn out heat insulating material,
Connector for controller connection at the end of each pair of lead wires
An electrothermally welded joint with the ー was installed.

[0014]

The connection between the plastic pipe and the joint must be easily performed irrespective of the diameter of the pipe, the type of the joint, and the conditions of the construction place. In particular, large-diameter pipes are large and heavy, so that it is desirable to be able to fuse them one by one, and it is indispensable that work in narrow places and the like is difficult and often dangerous. According to the present invention, a metal wire serving as a heating wire is arranged independently of each other for each joint port (without being connected to a metal wire of another joint port), and preferably, a lead wire of each joint port is connected to each other. Covered with thermal insulation drawn from the joint opening
With a pair of lead wires.
An EF joint that satisfies these conditions can be obtained by configuring the controller connection connector .

FIG. 1 shows one example of the EF joint of the present invention.
This shows a straight pipe type joint. The shape of the EF joint of the present invention is not limited to the illustrated one. That is, as long as the structure of the present invention is such that the heating wire is independent for each joint port, the shape and structure of the EF joint can be changed. For example,
The joint may be a curved pipe type two-port joint or a branch pipe type three-port or more multi-port joint. The present invention is particularly suitable for a multiport joint having three or more ports and a large diameter joint.

The joint body 1 of the EF joint shown in FIGS. 1A and 1B comprises a sleeve 2 made of resin and a metal wire 3 for heating embedded in an inner peripheral portion thereof. The metal wires 3 are arranged at the portions B and B 'of the respective joint ports A and A' where the heat welding with the plastic pipe is performed, but the metal wires of the respective joint ports are not connected to the metal wires of the other joint ports. Independent of each other. In the illustrated example, as shown in FIG.
A metal wire 3 in which the inner peripheral surface of (eg, joint port a) is wound inward from the end 1a side by the length of the welded portion B.
Turns at the inner end 1b of the fused portion B, is wound outward again, and returns to the end 1a. In order to melt the resin uniformly, the metal wire is wound as uniformly as possible. The winding interval of the metal wire may be selected so that there is no danger of short-circuit, and the desired resin can be melted and heated in a short time.

The material of the joint may be the same as that of a conventional EF joint. That is, the sleeve 2 is usually made of the same type of thermoplastic resin as the plastic pipe that is the pipe to be joined. For example, polyethylene, polybutene and the like are exemplified. The metal wire 3 is made of a metal or an alloy such as Ni, Cu, Cu-Ni, Ni-Cr that can be efficiently resistance heated.

The metal wire 3 is preferably covered with a covering material formed by braiding a heat-resistant insulating fiber material such as glass fiber. As a result, it is possible to reliably prevent the occurrence of a short circuit during energization, which causes a fusion defect. The coating for this purpose may be a relatively thin coating.

According to a preferred embodiment of the present invention, at each joint port of the joint body 1, a pair of lead wires 4 is connected from its end 1a.
a, 4b are drawn out. The lead wires 4 a and 4 b are extensions of both ends of the metal wire 3. The lead wires 4a, 4b
Although it can be pulled out from an arbitrary position of each joint port, it is convenient from the end of the joint port as shown in the drawing for manufacturing.

When the EF joint is energized, the lead wire is also heated, and the outside lead wire becomes high temperature, which may cause a burn or fire hazard to the worker. Therefore, the lead wires 4a and 4b are covered with the heat insulating material 5. Thus, it is preferable to avoid this danger. The heat insulating material is preferably flexible so that the lead wire can be bent. Suitable heat insulating materials include heat-resistant fiber materials such as glass fiber, carbon fiber, and rock wool fiber.

More specifically, the lead wire is passed through a tube formed by braiding these heat-resistant fiber materials to cover the metal wire at the lead wire portion. The type and thickness of the heat insulating material coating are not particularly limited as long as the surface temperature of the lead wire portion can be reduced to an extent sufficient to avoid the above danger. When the metal wire is coated with a heat-resistant insulating fiber material (eg, glass fiber) for insulation as described above, the metal wire is further coated with a heat-resistant fiber material for heat insulation, if necessary. If desired, the periphery of the thermal insulation coating can be further covered with another protective coating.

During energization, the metal wire is heated to a high temperature, and its resistance changes. At this time, if there is no heat insulating material, the resistance value may change due to the influence of wind or the like, so it is difficult to control the fusion temperature.However, if the heat insulating material covers the lead wire, heat radiation from the metal wire can be prevented. Such a change in resistance is suppressed, and it becomes easy to control the fusion temperature to be constant.

As shown in FIG. 1 (a), the ends of a pair of lead wires 4a and 4b drawn out from the ends of each joint port are connected to a connector 6 for connecting to a controller. The connector 6 has a shape adapted to the connection part of the controller. For example, when the connection portion is an outlet, the connection portion has a plug shape as illustrated.

The EF joint of the present invention can be used in the same manner as a conventional product. That is, as shown in FIG. 1 (b), after two pipes (plastic pipes) 7, 7 'are inserted into the joint from the joint ports A, A' on both sides of the joint, a controller serving as a power supply is provided. A predetermined current is supplied to the metal wire by connecting the connector 6 provided at the end of the lead wire of the joint to the connection portion of. The resin near the interface between the joint and the pipe to be connected is melted by the heat generated by the metal wire, and the joint and the pipe to be connected are fused.

According to the present invention, since each joint port is an independent electric heating circuit, all joint ports can be EF joints even if the joint is a multiport joint having three or more joints.
In addition, since each joint port is separately energized and fused with the pipe to be joined, even if the joint has a complicated shape or the pipe to be joined has a large diameter and is heavy or extremely long, it is difficult to work. Since the joining pipes need only be fused one by one, the work becomes easy.

Further, as shown in FIG. 1, by making the connection portion with the controller a lead wire and making it long, it is easy to perform construction in a place where work is difficult such as a narrow place.
Also, a connector attached to the end of the lead wire
(E.g., a plug) ensures reliable connection to the controller, stabilizes the amount of current, and increases connection reliability. That is, workability is remarkably improved as compared with the conventional one, and moreover, a stable connection result can be reliably obtained.

After energization, the lead wire is cut so that the next operation can be performed without affecting the joint during cooling and solidification. In addition, by cutting the lead wire at the root, it is possible to prevent an unnecessary protruding portion from remaining in the joint after construction.

The EF joint of the present invention can be manufactured by insert injection molding using a dedicated injection mold having a core and a mold, as in the prior art. Insert injection molding is performed by winding a wire around a core in a desired winding manner such as a coil shape, mounting the core in a mold, and injecting a resin into a gap between the core and the mold. E of the present invention
To manufacture the F-joint, one wire is wound at each joint mouth portion of the core such that the surplus portions (extended portions) at both ends are pulled out from the same position. Preferably, a pair of lead wires is formed using the extended portions on both sides drawn from the same position, and after injection molding, each lead wire is covered with a suitable heat insulating material, and the tips are connected to a connector. .

The wire used for manufacturing the EF joint is braided and coated with a heat-resistant insulating fiber material to prevent a short circuit.
Further, it is preferable to use a double-coated metal wire (hereinafter, referred to as a coated wire) coated with a jacket made of the same kind of plastic material as the resin constituting the joint body. In this way, short-circuits are reliably prevented, and by tightly winding the covered wire, metal wires can be wound at uniform intervals, the heat generation performance of the joints is homogenized, and product quality is stabilized. I do. The thickness of the plastic covering of the covering wire to be used can be determined according to the winding interval of the metal wire of the EF joint and the diameter of the joint. Since the plastic jacket of the covered wire is integrated with the injected molten resin during the injection molding, the manufactured joint has a structure in which the metal wire is embedded in the resin as shown in FIG. 1 (b). .

In the production of the EF joint of the present invention, it is preferable to extend the extended portions at both ends of the wire not embedded in the joint so that a lead wire is formed at each joint port. The extended portion of this long wire is liable to cause problems such as being caught in a mold during injection molding, and it is necessary to prevent resin from adhering to this portion during injection molding, which hinders a smooth molding operation. There is fear. In addition, in order to keep the extended portion of the wire long, it is necessary to perform injection molding with one or two-piece dies in a usual manner.

According to the present invention, there is no possibility of a defect such as pinching the wire by using insert injection molding using a metal wire, preferably a core wound with the above-mentioned covered wire and a mold. EF that can use multi-cavity molds
A method of manufacturing a joint is also provided. This manufacturing method will be described with reference to FIGS.
This will be described below.

The core and the mold to be used are arranged such that the lead wire forming part, the metal wire lead-out part, and the joint forming part are arranged at positions corresponding to the core and the mold in order from the end side for each joint opening. Have.

Specifically, as shown in FIG. 2, the outer diameter of each joint port of the core 10 is a diameter corresponding to the inner diameter of the joint port of the joint to be manufactured by the joint forming part 11, and the drawer part 12 is The diameter when the metal wire (covered wire) used for the core equivalent to the bore diameter is wound, or slightly larger than the diameter, so that the lead wire forming section 13 also has a diameter equivalent to the inside diameter of the joint port like the joint forming section. It has a unique shape. By winding the covered wire around the lead wire forming portion 13, the danger of pinching the covered wires at both ends, which become the lead wire, in the mold is eliminated. Therefore, the length of the lead wire forming portion is sufficient to wind a covered wire having a necessary length as a lead wire. On the core surface of the lead portion 12, two wire lead grooves 14 having the same width and the same depth as the diameter of the covered wire are formed in order to pass the covered wire in both directions. Preferably, the central part 15 of the joint forming part 11 of the core is
As shown in FIG. 2, the diameter is reduced. The small-diameter central portion 15 forms an annular protrusion of the joint that serves as a stopper when the joint is inserted. The core 10 may be a divided type divided for each joint port or an integral type.

As shown in FIG. 3, a covered wire is individually wound around each joint port of the core 10 one by one. That is, the coated wire 16
Is the lead wire forming part located on the end side of each joint port of the core
After the wire is wound inward from the end on the joint 13, the wire is passed through one of the wire drawing grooves 14 of the drawer portion 12 to the joint forming portion 11, and further wound inward around the joint forming portion. Turn the covered wire at the innermost part of the joint forming part, wind it in the opposite direction (outward), and pass the lead wire forming part through the
Return to 12, and further wrap it outward, keeping the beginning and end of winding at the end of the joint opening. Actually, the coated wire cut to the required length is first folded back at the center to make two wires,
Starting from the turn (turn) portion, the two covered wires are wound around the core outward from the innermost (center) side of each joint opening of the core as shown in FIG. If it goes through another groove), it can be wound easily. The covered wire is thus wound around all the joint ports.

On the other hand, the inner diameter of each joint opening of the mold 20 is
As shown in FIG. 4, the joint forming portion 21 has a diameter corresponding to the outer diameter of the joint, the lead portion 22 has a diameter corresponding to the outer diameter of the lead portion 11 of the core,
The lead wire forming part 23 has a shape having a diameter sufficiently separated from the diameter of the core wire equivalent to the joint inner diameter by winding the covered wire with a sufficient margin. Although not shown, the mold is naturally composed of two or more divided portions, and the joint forming portion 21 is provided with a resin injection port.

When the core is inserted into the mold, as shown in FIG. 5, the drawn portion 22 of the mold comes into close contact with the drawn portion 12 of the core, so that the resin 30 injected into the joint forming portion by injection molding.
Is prevented from flowing out. To prevent the resin from flowing out of the gap between the covering wire and the groove in the groove 14 of the drawer,
It is preferable that the lengths of the lead portions 12 and 22 be 15 mm or more. Even if a small amount of resin flows out of the coated wire drawing part,
Since there is enough space 31 in the lead wire forming part,
Almost no adhesion of the resin to the coated wire occurs. After injection molding the resin into the gap between the core and the mold of the joint forming part, remove the two covered wires wound around the lead forming part of each joint opening of the core to form a lead wire, and insulate each as necessary. The EF joint of the present invention is obtained by covering with a material and attaching a connector to the ends of the two covered wires.

When the core and the mold are used, the long end portions of the covered wire forming the lead wire are wound around the lead wire forming portion of the core. Obstacles at the time of injection molding such as sandwiching both ends of the wire between the molds are eliminated. Furthermore, since all of the covered wires are wound around the core, it is possible to take multiple pieces and improve production efficiency.

Next, the present invention will be specifically illustrated by way of examples.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the manufacturing method of the present invention, four joints each having a joint forming part, a covered wire lead-out part and a lead wire forming part are provided.
An EF joint having an outer diameter of 45 mm was manufactured by an insert injection molding method using an individual core and a mold. The resin used was polybutene, and as the coated wire, a Ni wire having a diameter of 0.5 mm was coated with a glass fiber braid, and further coated with a 0.6 mm thick polybutene. The dimensions of each part of the core and the mold were as follows.

Core (outer diameter) Mold (inner diameter) Length (mm) Joint forming part 34.5 46.5 65 Small diameter part at the center of joint forming part 25.5 46.5 5 Coated wire lead-out part 40 40 15 Lead wire forming part 34.5 50 25 The drawing portion was provided with two grooves for drawing a covered wire having a width and a depth of 2 mm and a lower half having a semicircular cross section.

After the coated wire was wound around the core as shown in FIG. 3, the core was fitted into a mold. At this time, there was no problem such as entrapment of the covered wire, and the multi-cavity core and the mold could be smoothly fitted. Next, the molding temperature of 195
The resin was injected into the joint forming section under the conditions of ° C, a molding pressure of 300 kg / cm ² , a mold temperature of 15 ° C, and a cycle time of 3 minutes to mold an EF joint. When this injection molding was repeated, a small amount of resin sometimes flowed out to the lead wire forming part, but the resin did not adhere to the covered wire in this part, and the lead wire was disturbed by removing it from the core after molding. It could be formed without.

After molding, the lead wires on both sides of each joint were
cm, and the lead wire was covered with a tubular heat insulating material having a length of 45 mm and a thickness of about 0.5 mm made of a braided glass fiber, and then a plug was connected to the end of the lead wire to complete an EF joint.

This EF joint could be easily and reliably constructed even in a narrow place simply by connecting the plug at the end of the lead wire to the outlet of the controller. Further, after energization, the next operation can be started promptly by cutting the lead wire at the root, and formation of an obstructive projection on the outer surface of the joint was avoided.

[0044]

According to the EF joint of the present invention, even if it is a multi-port joint having three or more ports, all the joint ports can be made EF joints, and workability is very good. That is, in the conventional EF joint, it is difficult to work on a narrow place or a large-diameter pipe. In addition, current can be supplied simply by connecting the connector at the end of the lead wire to the connection portion of the controller, so that the power supply state is stable and there is no variation in the fusion result. Moreover, by cutting the lead wires, the operation can be immediately shifted to the next operation without waiting for the cooling of the resin, thereby shortening the operation time.

The method of manufacturing an EF joint according to the present invention enables the injection molding operation to be performed smoothly, and also allows a large number of pieces to be formed. Thus, possible defects during injection molding can be avoided and the efficiency of the molding operation is significantly improved.

[Brief description of the drawings]

FIG. 1 (a) is an explanatory view of an EF joint of the present invention, FIG.
(b) is a schematic partial enlarged cross-sectional view of the EF joint of the present invention in a state where a pipe to be joined is inserted.

FIG. 2 is an explanatory diagram showing an outer shape of a core.

FIG. 3 is an explanatory view showing a state where a covered wire is wound around a core.

FIG. 4 is an explanatory sectional view showing an inner surface shape of a mold.

FIG. 5 is an explanatory view showing a state in which the core shown in FIG. 3 is mounted on the mold shown in FIG. 4 and then a resin is injected.

[Explanation of symbols]

1: Joint body 2: Resin sleeve A, A ': Joint port B, B': Fused portion 3: Metal wire 4a, 4b: Lead wire 5: Heat insulating material coating 6: Connector 7, 7 ': Pipe to be joined 10 : Core 16: Insulated wire 20: Die 11, 21: Joint forming part 12, 22: Insulated wire lead-out part 13, 23: Lead wire forming part 14: Insulated wire lead-out groove 30: Resin 31: Leading part space

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-140593 (JP, A) JP-A-2-11997 (JP, A) JP-A-2-256997 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F16L 47/00-47/02 B29C 65/36

Claims (1)

(57) [Claims] 1. A method for manufacturing a plastic electrothermally welded joint by insert injection molding using a core around which a metal wire is wound and a mold, wherein the core and the mold are provided at each joint opening. The lead wire forming portion, the metal wire drawing portion, and the joint forming portion are provided at positions corresponding to the core and the mold in order from the end side, and the outer diameter of the core is determined by the joint forming portion and the lead wire forming portion. The diameter corresponding to the inner diameter of the joint port, the lead portion is the diameter when the metal wire is wound around a core substantially equivalent to the inner diameter of the joint port, and the core surface of the lead portion has the same width and depth as the metal wire diameter. Two wire drawing grooves are provided, and the inner diameter of the mold is such that the joint forming portion has a diameter equivalent to the outer diameter of the joint port,
The lead-out portion has a diameter corresponding to the outer diameter of the lead-out portion of the core, and the lead wire forming portion has a diameter sufficiently separated from the diameter of the metal wire wound around the core corresponding to the inside diameter of the joint opening. After winding another metal wire for each joint port around the joint forming section, drawer section, and lead wire forming section,
The core is mounted in a mold, characterized by injecting a resin in the core and the mold gap of the joint forming portion, plastic-made electric welding joint method of manufacturing.