JPS6346548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a planar heating element in which heating wires are sandwiched between sheets of heat-fusible synthetic resin, such as silicone rubber, into a pipe shape having any desired cross-sectional shape. It is something.

Planar heating elements, especially silicone rubber heaters (product name) using sheets of silicone rubber, have excellent thermal response, are extremely thin and flexible with a thickness of 0.8 mm (standard type), and have a long life. It is large, safe, moisture resistant, weather resistant, chemical resistant, and has wide temperature characteristics from -70°C to 260°C, making it suitable for a wide range of applications from household electrical equipment and medical equipment to aviation equipment. Used for needs. A sheet heating element is generally used by heating it by placing it in close contact with a metal surface, and it has been desired to form the sheet heating element into a pipe shape with an arbitrary cross-sectional shape. Since pressurization and heating were performed only by pressing, there was a limit to molding, and sheet heating elements could only be molded into relatively simple cross-sectional shapes such as circular pipes. Moreover, in the case of a circular pipe, since it was formed using two molds, one above and the other, lines were formed in the part that corresponds to the parting surface of the mold, and the heating wire was bent along the lines, making it easy for the heating wire to break. There was a problem.

The present invention is intended to solve the above-mentioned problems, and aims to provide a molding method that can satisfactorily mold a sheet heating element into a pipe shape having any desired cross-sectional shape. be.

That is, in the present invention, positioning pins are planted in a mold having self-holding force, heating wires are wired to the positioning pins on the upper surface of the mold, and then a heating wire with good releasability is placed on the positioning pins and heating wires. A first heat-welding resin sheet is placed and heated under pressure between the mold and a hot plate to bond and transfer the heating wire to the first heat-welding resin sheet, and at the same time, the positioning pin is pushed into the mold. A bonding transfer step in which the heating wires are bonded and transferred is turned over, and a second heat bonding resin sheet with good mold releasability is applied onto the transferred first heat bonding resin sheet. A sandwich adhesion step in which welding resin sheets are overlapped and heated under pressure between the mold and a hot plate, and the planar heating element preformed by the bonding transfer step and the sandwich adhesion step in a sealed mold is shaped into a desired curved surface. A molding step is performed in which a pipe having a square or square cross-sectional shape is heated under pressure using synthetic rubber and molded into a pipe having an arbitrary desired cross-sectional shape.

According to the above configuration, by performing the bonding transfer process and the clamping adhesion process, it is not necessary to drill holes in the resin sheet for passing pins, so that the planar heating element having a completely waterproof structure can be preformed. be done. Then, by performing the above-mentioned molding process using synthetic rubber, the sheet heating element can be well formed into a pipe shape without any lines and having any desired cross-sectional shape, and the heating wire can be formed along the lines. It will not bend and the heating wire will not break. Furthermore, according to the molding method of the present invention, the first and second heat-welded resin sheets made of, for example, silicone rubber have good mold releasability, so it is easy to make the heat-welded resin sheets after molding from the synthetic rubber used in the molding process. It can be peeled off.

The present invention will be described below with reference to an embodiment shown in the drawings. In FIG. 1, 1 is a lower mold, 2 is an intermediate mold, 3 is an upper mold, 4 is synthetic rubber, and 5 is a preformed sheet heating element, which is made of heat-welding resin with good mold release properties. A nickel alloy heating wire is sandwiched between sheets, for example, silicone rubber sheets with a thickness of 0.4 mm. 6 indicates a circular pipe, and 7 indicates a core metal.
A flow hole 2a is bored in the lower part of the intermediate mold 2.

In the above configuration, first the intermediate mold 2 is filled with synthetic rubber 4, and when the upper mold 3 and the lower mold 1 are pressurized from above and below with a hot plate of a heat press (not shown), the synthetic rubber 4 is It is pressurized between the mold 2 and gradually flows through the flow holes 2a, filling the lower mold 1. Then, the planar heating element 5 inside the lower mold 1
The synthetic rubber 4 presses the entire circumference toward the pipe 6 evenly and strongly, and the hot plate heats the sheet heating element 5, so that the sheet heating element 5 can be moved along the surface shape of the pipe 6 without creating any streaks. Can be formed into a good circular pipe shape. Note that the synthetic rubber 4 is peeled off from the heat-welding resin sheet after being pressurized and heated and discarded.

Furthermore, the planar heating element 5 can be formed by using a pipe 6 having any desired cross-sectional shape such as a triangle, U-shape, chevron-shape, or narrow inverted U-shape as shown in FIGS. 2a, b, c, and d. These special shapes can be molded in the same manner, and any other shapes can also be molded.

In addition, the method of preforming is shown in FIGS. 3a, b, c, d, and e. In the heating wire wiring process shown in FIG. 3a, 8 is a mold that has a self-holding force by sandwiching a rubber plate 8a. 9 is pin, 10
is the heating wire wired to pin 9. In the transfer process shown in FIG. 3b, 11 is a silicone rubber sheet reinforced with glass cloth, and when the mold 8 and the silicone rubber sheet 11 are pressurized and heated from above and below using a hot press, the heating wire 10 is attached to the silicone rubber sheet 11. Since the pins 9 are bonded by transfer and are buried in the mold 8, the heating wires 10 can be easily separated from the pins 9. Subsequently, in the clamping adhesion step shown in FIG. 3c, another silicone rubber sheet 12 is placed on top of the silicone rubber sheet 11 to which the heating wire 10 has been transferred and bonded, and heated under pressure using a hot press. In the terminal connection process shown in Figure 3d,
A lead wire 14 such as a Teflon wire is connected to the end of the heating wire 10 via a terminal plate 13. Finally, in the terminal protection step shown in FIG.
A preformed planar heating element can be obtained by placing the heating element on the heating element and applying pressure and heating using a hot press.

In addition, in the embodiment shown in FIG.
When performing a similar molding process with an adhesive or primer applied between the and the sheet heating element 5,
The planar heating element 5 can be formed into a good circular pipe shape without streaks, and at the same time, the heating element 5 can be brought into close contact with the pipe 6 for strong adhesion,
The fluid passed through the pipe 6 can be efficiently heated.

As described above, according to the present invention, the planar heating element can be well formed into a pipe shape having any desired cross-sectional shape without streaks, the heating wire does not break, and the heated pipe The heat-welding resin sheet can be molded so that it adheres closely to the outside of the synthetic rubber, has high heating efficiency, and has good mold releasability and can be easily peeled off from the synthetic rubber after the molding process. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the method of this invention, FIGS. 2a, b, c, and d are schematic sectional views showing other examples of special shapes obtained by the method of this invention, and FIG.
Figures a, b, c, d, and e are perspective views showing an example of a method for preforming a sheet heating element. 1...Lower mold, 2...Middle mold, 3...Upper mold, 4...
... Synthetic rubber, 5 ... Planar heating element, 6 ... Circular pipe, 7 ... Core metal.

Claims (1)

[Claims] 1. After installing positioning pins in a mold having self-holding force and wiring heating wires to the positioning pins on the upper surface of the mold, a wire with good mold releasability is placed on the positioning pins and heating wires. A first heat-welding resin sheet is arranged and heated under pressure between the mold and a hot plate to join and transfer the heating wire to the first heat-welding resin sheet, and at the same time, the positioning pin is inserted into the mold. A bonding transfer step in which the heating wires are bonded and transferred is turned over, and a second heat-fusible resin sheet with good mold releasability is placed on top of the transferred first heat-fusible resin sheet. A sandwich adhesion step in which the heat-welding resin sheets are overlapped and heated under pressure between the mold and the hot plate, and the planar heating element preformed by the bonding transfer step and the sandwich adhesion step in the sealed mold is shaped into the desired shape. A method for forming a planar heating element, comprising the steps of pressurizing and heating a pipe having a curved or angular cross-sectional shape using synthetic rubber, and forming the pipe into a pipe having an arbitrary desired cross-sectional shape. .