JP2513876Y2 - Heating mat - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating mat used for a branch welding joint which is welded and joined in the middle of a pipeline such as a gas pipe or a water pipe made of synthetic resin.

[0002]

2. Description of the Related Art Conventionally, as a heating mat used in a branch welding joint, for example, one described in JP-A-58-65624 is known.

In this conventional heating mat, a conductive wire is inserted inside a spiral groove formed on one surface of a resin sheet, and one end of the conductive wire traverses the spiral groove from the inner end of the spiral groove. Was pulled out to the outside.

[0004]

However, in such a conventional heating mat, since one end of the conductive wire crosses the spiral groove, the conductive wire in the spiral groove is dislocated from the groove and protrudes. If this happens, the protruding portion may come into contact with one end of the conductive wire that crosses the spiral groove and cause a short circuit during energization. When the conductive wire is short-circuited, the resin around the conductive wire is excessively overheated, which causes a defective welding when used in the branch welding joint. It is also possible to make the spiral groove deeper to increase the distance between the conductive wire in the spiral groove and the end of the conductive wire that crosses the spiral groove. In addition to being disadvantageous in terms of surface, it is difficult to perform work such as bending the heating mat along the core when forming the branch welding joint. Further, if the spiral groove is deepened, there is a problem that the work of inserting the conductive wire becomes difficult.

In view of the above-mentioned conventional problems, the present invention aims to provide a heating mat in which a short circuit does not occur between the conductive wire in the spiral groove and the end of the conductive wire traversing the spiral groove. .

[0006]

To achieve the above object, in the heating mat of the present invention, the heating mat is embedded in the branch welding joint, and is swirled on one side of a resin sheet made of a thermoplastic resin. A groove is formed, a conductive wire as a heating element is inserted inside the spiral groove, and one end of the conductive wire is drawn out from the inner end of the spiral groove to the outside of the spiral groove. In the heating mat, the end portion of the conductive wire that crosses the spiral groove is covered with an insulating tube.

[0007]

In the heating mat of the present invention, since the end of the conductive wire that crosses the spiral groove is covered with the insulating tube, even if the conductive wire in the spiral groove protrudes from the spiral groove, One end of the conductive wire that traverses the spiral groove is maintained in an insulating state by an insulating tube.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. First, the configuration of the first embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing a heating mat of this embodiment, and FIG. 2 is a sectional view taken along line II-II of FIG. 1, in which 1 is a resin sheet, 2 is a conductive wire, and 3 is an insulating tube.

The resin sheet 1 is made of polyethylene resin, which is a thermoplastic resin, and has a rectangular shape. A hole 11 is formed in the center of the resin sheet 1, and a spiral groove 12 is formed on one surface of the resin sheet 1 so as to surround the hole 11 so as to cover almost the entire surface. The resin sheet 1 may be made of a thermoplastic resin, such as polyethylene resin, polypropylene resin,
You may use polyvinyl chloride resin, polybutene resin, ABS resin, etc.

The conductive wire 2 serves as a heating element and is inserted into the spiral groove 12 of the resin sheet 1, and one end thereof is connected to the terminal pin 15 from the outer end of the spiral groove 12, and the other end. The end portion is drawn from the inner end of the spiral groove 12 across the spiral groove 12 to the outside of the spiral groove 12 and is connected to the terminal pin 16. For the conductive wire 2, a wire for general resistance such as iron chrome, nichrome, chromel, copper nickel, copper manganese nickel can be used. The conductive wire 2 preferably has a wire diameter of 0.3 to 1.5 mm. In that case, the spiral groove 1 formed in the resin sheet 1
It is preferable that the depth of the wire 2 is 1.2 to 3 times the wire diameter of the conductive wire 2 and the width thereof is wider than the wire diameter of the conductive wire 2 by about 0.01 to 0.03 mm.

The insulating tube 3 is put on the end of the conductive wire 2 that crosses the spiral groove 12 of the resin sheet 1. The insulating tube 3 is formed in a cylindrical shape, and as shown in FIG. 3, the slit 31 is narrower than the diameter of the conductive wire 2.
Is formed so as to extend in the axial direction so that the end portion of the conductive wire 2 can be covered even after the conductive wire 2 is connected to the terminal pins 15 and 16.

The insulating tube 3 preferably has an inner diameter equal to or larger than the diameter of the conductive wire 2 and a thickness of 2 mm or more. The length of the insulating tube 3 needs to be at least long enough to cross the spiral groove 12 of the resin sheet 1, and preferably, the spiral groove 12 is preferable.
The length required to cross the + is about 10 mm. Further, the material of the insulating tube 3 may be a synthetic resin, but the same material having the same color as the resin sheet 1 is preferable.

In order to prevent the conductive wire 2 from protruding from the spiral groove 12 of the resin sheet 1, after inserting the conductive wire 2 into the spiral groove 12, a heater is applied from above the spiral groove 12. Alternatively, the surface of the resin sheet 1 may be slightly melted, and the conductive wire 2 and the resin sheet 1 may be welded. As a means for melting the resin sheet 1, a high frequency wave or an ultrasonic wave can be used instead of the heater.

As described above, in the heating mat of this embodiment, since the insulating tube 3 is covered on the end of the conductive wire 2 which crosses the spiral groove 12 of the resin sheet 1, the spiral groove 12 is formed.
Even if the inner conductive wire 2 protrudes from the spiral groove 12, the protruding portion and one end of the conductive wire 2 that crosses the spiral groove 12 are maintained in an insulating state by the insulating tube 3. Therefore, it is possible to prevent a short circuit from occurring between the conductive wire 2 inside the spiral groove 12 and the end portion of the conductive wire 2 that crosses the spiral groove 12 during energization.

Next, the configuration of the second embodiment will be described with reference to FIG. The heating mat of this embodiment is an insulating tube 3.
a is formed in a cylindrical shape having no slit. In this case, a hollow gate that remains when the resin sheet 1 is injection-molded can be used as the insulating tube 3a. Further, the insulating tube 3a needs to cover the end of the conductive wire 2 before connecting the end of the conductive wire 2 that crosses the spiral groove 12 of the resin sheet 1 to the terminal pins 15 and 16. Then, after covering the end portion of the conductive wire 2, it is desirable to weld the resin sheet 1 from above the spiral groove 12. Since the structure other than the insulating tube 3a is the same as that of the first embodiment, the drawing and description thereof are omitted.

FIG. 5 is a sectional view showing a welded branch saddle. The heating mat M is a saddle portion 10 of this welded branch joint S.
It is used by embedding it in the inner peripheral part of. Therefore, the outer diameter of the insulating tubes 3 and 3a used for the heating mat M is
In order to prevent the insulating tubes 3 and 3a from appearing on the surface of the product, the thickness of the saddle part 10 is set to 0.8 or less.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Is also included in the present invention. For example, although the resin sheet has a square shape in the embodiment, it has a circular or elliptical shape.
It may be polygonal or the like. Further, in the embodiment, the insulating tube has a cylindrical shape, but it may have a polygonal tube shape such as a square tube shape or a triangular tube shape. Further, the heating mat can be used, for example, in a welding and branching service station, in addition to the welding and branching saddle.

[0018]

As described above, in the heating mat of the present invention, even if the conductive wire in the spiral groove protrudes from the spiral groove, the protruding portion and one end of the conductive wire that crosses the spiral groove. Since the insulating portion maintains the insulating state by the insulating tube, it is possible to prevent a short circuit from occurring between the conductive wire in the spiral groove and the end of the conductive wire that crosses the spiral groove during energization. Is obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a heating mat according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view showing an insulating tube used in the heating mat of the first embodiment.

FIG. 4 is a perspective view showing an insulating tube used in the heating mat of the second embodiment.

FIG. 5 is a cross-sectional view showing a branch welding saddle.

[Explanation of symbols]

 M heating mat 1 resin sheet 12 spiral groove 2 conductive wire 3 insulating tube S welding branch saddle (welding branch joint)

Claims (1)

(57) [Scope of utility model registration request] 1. A heating mat embedded in a branch welding joint, wherein a spiral groove is formed on one surface of a resin sheet made of a thermoplastic resin, and a conductive wire as a heating element is inserted inside the spiral groove. In the heating mat which is attached and one end of the conductive wire is drawn out from the inner end of the spiral groove to the outside of the spiral groove, an insulating tube is provided at the end of the conductive wire that crosses the spiral groove. A heating mat characterized by being covered with.