JPS588115B2 - Hatsunetsoshino Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a heating element that radiates far infrared rays by electrical heating, and is used, for example, to heat and dry substances that easily absorb far infrared rays (such as water). used for

Conventionally, there are those in which a metal resistance heating wire is inserted into a quartz tube or glass ceramic tube, and those in which a metal resistance heating wire is embedded in a ceramic.

As an example of the latter, in order to eliminate cracks in the ceramic due to the difference in thermal expansion between the metal resistance heating wire and the ceramic, a heating wire wrapped in thin paper is buried in the ceramic and the thin paper disappears at the same time as the ceramic is fired. Method of creating a gap between ceramic and ceramic (Special Publication No. 36-15839)
In addition, a heating wire is submerged in an oily resin liquid, the resin liquid adhering to the surface is hardened, and after being buried in ceramic,
A method to make ceramic disappear at the same time as it is fired (Tokuko Sho 4
0-3351).

In these known methods, when thin paper is used, the thin paper is easily damaged by moisture in the ceramic during the process of embedding it in the ceramic, and it is often impossible to obtain the desired space.

Furthermore, if the diameter of the heating wire is small, the space created will be larger than the diameter of the heating wire, and from the point of view of thermal efficiency, there will be condensation, so it is recommended to wrap thin paper around a thin wire of about 0.1 mm. is also extremely difficult.

In order to solve the above problem to some extent, if a method is used in which a heating wire is submerged in an oily flammable resin liquid and the resin liquid that reaches the surface is cured, the resin liquid is cured from the submerged state. During the process, the oily resin adhering to the surface of the heating wire flows downward due to its own weight, which often results in uneven thickness of the resin film covering the surface of the heating wire.

Moreover, if the heating wire is made into a coil shape with a small pitch, the coating resin will adhere to each other, creating a so-called tubular shape. If the heating wire becomes soft due to electrical heating, there is a concern that adjacent coils may come into contact with each other, which is extremely dangerous.

In order to solve the above-mentioned problems, the present invention coats the surface of a metal resistance heating wire with flammable resin powder to form a combustible resin film, and then coats the surface of a metal resistance heating wire with a flammable resin film, which is then placed inside a moist ceramic material. After burying and press-molding the ceramic powder and drying and solidifying it, the solidified heating wire is energized and the flammable resin film disappears, making it possible to reduce the thickness of the resin regardless of the shape and size of the heating wire. The object of the present invention is to provide a method of manufacturing a heat generating element that not only has uniformity but also allows control of the thickness and is inexpensive in terms of cost.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in Figure 1, metal resistance heating wire 1 processed into a coil shape
into the epoxy powder, apply a voltage of 100V to this heating wire 1 for 10 seconds to make the epoxy powder adhere to the surface of the heating wire 1, then take it out from the epoxy powder and continue until the epoxy powder hardens. A voltage of 100 V is applied for 5 seconds to form a combustible resin film 2 with a thickness of 0.05 mm on the surface of the heating wire 1 (see FIG. 2).

10-35 mesh cordierite 46wt% and 20
19% SiOz sol 30% solution was added to 800g of ceramic powder mixed with 54wt% of silicon nitride of 0 mesh or less.
Add 0ml and knead.

This ceramic slurry is filled into a mold (not shown), a heating wire 1 having a flammable resin film 2 formed by the above-mentioned powder coating is embedded, and the mold is pressed under a pressure of 100 kg/cm2.

Then, the molded product 3 obtained after pressing (see Fig. 3) was removed from the mold, dried indoors for 12 hours, and further dried for 12 hours.
Dry in a hot air dryer at ℃ for 5 hours to solidify.

After that, a voltage of 200V is applied to the heating wire 1 for about 10 minutes to make the flammable resin film 2 disappear, and a minute gap corresponding to the thickness of the combustible resin film 2 is created between the ceramic 4 and the heating wire 1. Made.

In the above embodiment, epoxy resin, which is a thermosetting resin, was used as the material for the combustible resin film 2, but it may also be a polyethylene resin, which is a thermosetting resin, for example.
Any resin may be used as long as the resin powder adheres to the surface when combustible resin powder is applied, the resin powder adhering to the excess portion easily falls off (fluidity), and the resin hardens when energized.

Furthermore, the ceramic powder is not limited to the mixture of cordierite and silicon nitride in the above embodiment, and of course, for example, alumina powder may be used.

As in the above example, when a coarse-grained ceramic powder with a small thermal expansion coefficient and a fine-grained ceramic powder with a large thermal expansion coefficient, such as a mixture of cordierite and silicon nitride, are kneaded and molded, the resulting molded Since the coefficient of thermal expansion of the material depends on the coefficient of thermal expansion of the coarse ceramic powder, it is advantageous against cracking due to thermal stress caused by temperature differences in the ceramic molded body itself.

As described above, in the present invention, the surface of the metal resistance heating wire is powder coated with flammable resin powder to form a flammable resin film, so the shape and diameter of the metal resistance heating wire are The flammable resin film can be coated with a uniform thickness on the surface of the metal resistance heating wire regardless of its size, and therefore the thickness of the flammable resin film covering the surface of the metal resistance heating wire can be reduced as in the conventional latter one. Various problems caused by unevenness can be solved.

In addition, by simply controlling the energization time of the metal resistance heating wire, it is possible to appropriately control the amount of flammable resin powder coated on the surface of the metal resistance heating wire. The thickness of the film can be controlled.

Furthermore, in the present invention, the moistened ceramic material is only dried and solidified without being fired, so a high-temperature treatment step during firing is unnecessary, which is very advantageous in terms of cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a metal resistance heating wire used in the present invention;
FIG. 2 is a partially broken sectional view showing the metal resistance heating wire shown in FIG. 1 covered with a flammable resin film, and FIG. 3 is a perspective view showing the heating element obtained by the present invention. 1... Metal resistance heating wire, 2... Flammable resin film, 3... Ceramic.

Claims (1)

[Claims] 1. The process of powder coating the surface of the metal resistance heating wire with flammable resin powder to form a flammable resin film, and embedding the metal resistance heating wire from this process in a moist ceramic material and pressurizing it. It is characterized by comprising a step of molding, a step of drying and solidifying the press-molded product, and a step of energizing the metal resistance heating wire after the solidifying step to burn out the combustible resin film on the surface of the metal resistance heating wire. A method for manufacturing a heating element.