JPH0642689A - Mat, manufacture of electrofusion saddle joint and joint - Google Patents

Abstract

PURPOSE:To prevent electrical heater wires from making contact with each other, and to prevent the electrical heater wires from floating up to the outer surface of a disc-like mat in which the heating wires are spirally coiled, and made of a thermoplastic resin sheet which is radially fused by a heated blade, by shifting the inner peripheral ends of the heater wires from the diametrical lines on which the outer peripheral ends thereof are positioned. CONSTITUTION:The inner peripheral ends of electrical heater wires 6 adapted to be fused by a heated blade are shifted from diametrical lines on which the outer peripheral ends of the heater wires 6 are positioned, laterally by a predetermined distance. In order to separate the inner peripheral ends of the electrical heater wires away from the diametrical lines on which the outer peripheral ends thereof are positioned, jumper wires 11 extending from the inner peripheral ends fused and secured, for example, on the equator of a mat 7 are prolonged circumferentially so as to be shifted from the equator, and are then fused and secured by the heated blade. Further, after the mat 7 is fitted in dies, the jumper wires 11 extending from the fixed positions at the inner and outer terminal ends are stretched with no slack and are connected to terminal pins 8, and indicator pins 9 are inserted before injection molding. Thereby, it is possible to prevent the jumper wires from making contact with the heating wires so as to cause short-circuiting, and to prevent them from floating up to the outer surface of the mat 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in the manufacture of an electrofusion saddle joint, and uses a disc-shaped mat made of a thermoplastic resin sheet in which a heating wire or a covered wire is wound in a spiral shape, and this mat. The present invention relates to a method of manufacturing an electrofusion saddle joint.

[0002]

2. Description of the Related Art An electrofusion joint has been recently developed as a joint for plastic pipes used for water and sewer pipes and gas pipes, and one of them is an electrofusion joint used to connect a branch pipe to a main pipe. There is a saddle joint. This joint consists of a molded product in which a heating wire is embedded in a spiral shape at the joint around the opening leading to the branch pipe of the saddle pressed against the main pipe. After pressing the joint to the side surface of the joint and connecting the connector at the cord end connected to the power source to each terminal of the joint, energize for a certain period of time to heat and melt the joint.

As shown in FIG. 1, an electrofusion joint is formed with a protruding indicator 2 which reaches the joint surface from a heating wire 1 which is buried inside, and the indicator 2 melts to confirm fusion when energized. In the electrofusion joint, the above-mentioned indicator is generally formed on the parting line separating the mold together with the terminal.

As a conventional method for manufacturing an electrofusion saddle joint having such an indicator, as shown in FIGS. 2 and 3, a vortex-like shape is formed around an opening 4 on one side of a disk 3 made of a thermoplastic resin sheet. Forming the groove 5 of
A heating wire or a covered wire (hereinafter simply referred to as a heating wire) 6 is inserted into the groove 5 in a vortex difference shape, and then a mat 7 is used to fix the heating wire 6 by fusing the heating blade radially at appropriate intervals. (1 in the figure
(0 indicates a fused portion), as shown in FIG. 4, this mat 7 is attached to a mold, and heating wires extending from the inner and outer peripheral ends fixed on the equator line are connected to terminal pins 8, respectively, and A method is known in which the indicator pin 9 is inserted until it reaches the mat, and then injection molding is performed.

In such a joint, in order to secure a space for inserting the connector around the terminal, the terminal is provided at a distance from the inserting portion into which the branch pipe is inserted. Therefore, when connecting the heating wire of the mat to the terminal pin, even if the heating wire connected to the outer peripheral edge can be extended straight up and connected to one terminal pin,
The heating wire connected to the inner peripheral edge must be extended to the outer peripheral side and connected to the other terminal pin. When the heating wire is wound around the mat, the winding is generally started from the inner circumference on the equator line and ended at the outer circumference, and the inner and outer circumference ends are located on the diameter line of the mat and the inner circumference end To connect the connecting heating wire to the terminal pin, pull it straight out to the outer peripheral side, and when the indicator pin is inserted, the wire connecting to the terminal pin is pushed down by the indicator pin and wound into the mat in a spiral shape. Molded in contact with heating wire,
After that, it will short-circuit when the power is turned on.

In order to avoid this problem, conventionally, before mounting on the mold, the connecting wire 11 connected to the inner peripheral end of the mat 7 is bent as shown in FIG.
I was trying to avoid.

[0007]

As described above, when the mating wire is bent and then the mat is attached to the mold and injection molding is performed, the bent mating wire is in a slackened state. May come into contact with the heating wire wound on the mat,
It floats and becomes exposed on the product surface. The present invention is
An object of the present invention is to provide a mat capable of solving the above problems, a method for manufacturing an electrofusion saddle joint using the mat, and a joint obtained by the manufacturing method.

[0008]

According to the mat of the present invention, the inner peripheral end of the heating wire fused and fixed by the hot blade is displaced a certain distance laterally from the diameter line where the outer peripheral end is located. It is characterized by. As the hot blade used in the present invention,
For example, a cartridge heater or a plate heater whose temperature can be controlled is used, and the shape and size of these heaters are slightly different depending on the target product.

Further, in order to separate the inner peripheral end of the heating wire from the diameter line where the outer peripheral end is located, for example, a mat as shown in FIG. 2 is used, and it extends from the inner peripheral end fused and fixed on the equator line. As shown in FIG. 6, the wire 11 is extended in the circumferential direction by a certain amount, shifted from the equator line, and then fused and fixed with a hot blade. When winding the heating wire in a spiral in the groove of the mat, It is possible to adopt a method in which the winding start position is shifted from the equator line 13 and the winding end is performed on the equator line, and the heat blade radially fuses.

According to the mat of the present invention, as shown in FIG. 7, the connecting wire 11 can be connected to the terminal pin 8 straightly without slack by avoiding the indicator pin 9 from the fastening position at the inner peripheral end. . The method for manufacturing an electrofusion saddle joint of the present invention is characterized by using the above mat, mounting it on a mold, and performing injection molding as in a conventional method.

That is, the mat is attached to a mold, the connecting wires extending from the fastening points at the inner and outer peripheral ends are straightly connected to the terminal pins without slack, and the indicator pins are inserted, followed by injection molding. It consists of The electrofusion saddle joint of the present invention is characterized by being obtained by the above manufacturing method using the above mat.

It should be noted that, at the time of injection molding, the fixing portion by the hot blade is melted, but the heating wire is not loosened by this. Incidentally, when the present inventors conducted a fluoroscopic experiment using X-rays at the time of molding, no deviation of the heating wire or the transfer wire was observed.

[0013]

The present invention is constructed as described above and has the following effects. According to the mat of claim 1, the indicator pin can be avoided by simply extending the connecting wire extending from the fastening portion at the inner peripheral end without slack and connecting it to the terminal pin, and there is no slack in the connecting wire. Therefore, it does not come into contact with other wires or rise during molding.

According to the manufacturing method of the second aspect, by using the mat according to the first aspect of the invention, the electrofusion saddle joint is prevented from causing the conductor wire to come into contact with the heating wire to cause a short circuit or float on the surface. Can be obtained. According to the joint as set forth in claim 3, the fusion wire does not come into contact with the heating wire to cause a short circuit or float on the surface during fusion.

[Brief description of drawings]

FIG. 1 is a sectional view of an indicator portion of an electrofusion joint.

FIG. 2 is a plan view of a conventionally used mat.

3 is an enlarged sectional view taken along line AA of FIG.

FIG. 4 is a cross-sectional view showing the positional relationship between the mat, the terminal pins, and the indicator pins when the mat is attached to the mold.

FIG. 5 is a plan view of a mat used in a conventional method.

FIG. 6 is a plan view of the mat according to the present invention.

FIG. 7 is a view showing a positional relationship among a connecting wire, an indicator pin and a terminal pin in the method of the present invention.

[Explanation of symbols]

2 ... Indicator 3 ...
Disk 4 ... Opening 6 ...
Heating wire 7 ... Mat 8 ...
Terminal pin 9 ... Indicator pin 11 ...
・ Passing line 13 ... Equator

Claims (3)

[Claims] 1. A disk made of a thermoplastic resin sheet, which is used when manufacturing an electrofusion saddle joint, in which a heating wire or a covered wire is spirally wound, and a required portion is radially fused with a hot blade. In the mat-like mat, the inner peripheral end of the heating wire that is fused and fixed by a hot blade is shifted a certain distance laterally from the diameter line where the outer peripheral end is located. 2. The mat according to claim 1 is attached to a mold, and connecting wires extending from the fastening points at the inner and outer peripheral ends are straightly connected to the terminal pins without any slack, and the mat of A method for manufacturing an electrofusion saddle joint, comprising inserting a pin for forming an indicator pin into a cavity of a mold and then performing injection molding. 3. An electrofusion saddle joint manufactured using the mat of claim 1 by the method of claim 2.