JPS62110285A - Sheath heater molding material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heater used as a heating source in a wide range of product fields such as general cooking utensils and heating equipment. The present invention relates to a sealing material for a sheathed heater used to seal both ends of a pipe.

Conventional technology Sheathed heaters are simple, safe, and have excellent corrosion resistance, making them suitable for use in ovens, microwave ovens, rice cookers, and hot plates.

It is widely used as a heating source for cooking appliances such as electric stoves and heating appliances.

This sheathed heater generally consists of inserting a coiled heating wire with terminal bars at both ends into the center of a metal pipe, filling the metal pipe with electrically insulating powder made of magnesia powder, and then It is manufactured by sealing both ends with a sealing material for a sheathed heater, and then reducing the diameter by rolling.

Conventionally, cardboard has been mainly used as a sealing material for such a sheathed heater.

This is because it is extremely low cost and can flexibly respond to shrinkage during rolling diameter reduction.

Problems to be Solved by the Invention However, in the manufacturing process of a sheathed heater, heat treatment is sometimes performed after rolling to reduce the diameter due to the following two reasons.

(1) In order to bend metal pipes work-hardened by rolling diameter reduction into various shapes, metal pipe i1050°C ~
Solid solution treatment is carried out in a reducing atmosphere of 110°C.

(2) When magnesia powder to which silicone resin is added is used as the electrical insulating powder, water repellency treatment is performed in the air at 200 to 300°C.

When such heat treatment (200°C to 1100°C) is carried out, the conventional sealing material for sheathed heaters made of cardboard easily carbonizes, resulting in damage between the metal pipe and the heating wire. Electrical characteristics deteriorate significantly.

Therefore, after the heat treatment, the carbonized sealing material for the sheathed heater is removed by a method such as air blowing, which is very difficult.

The present invention solves these problems and provides a sealing material for a sheathed heater that does not require removal even if a heat treatment process of 200°C or higher is performed after diameter reduction by rolling. The purpose is to

Means for Solving the Problems In order to solve all of the above problems, the present invention is constructed using inorganic fiber paper containing at least alumina fiber or silica fiber as a main component.

Function The main component of cardboard conventionally used as a sealing material for sheathed heaters is straw, and the temperature is 1050°C to 110°C.
In a reducing atmosphere of 0C or in an air atmosphere of 200°C to 300°C, carbonization occurs without being completely oxidized.
Adversely affects electrical properties.

However, since the sealing material for a sheathed heater of the present invention is composed of an inorganic material whose main component is at least alumina fiber or silica fiber, it is not easily carbonized even under the above-mentioned heat treatment conditions.

Furthermore, even if a small amount of organic matter contained as a binder is carbonized, the organic matter content is significantly lower than that of cardboard, which is a conventional sealing material for sheathed heaters, so no significant deterioration in electrical properties is observed. .

For this reason, there is no need to particularly remove the sheathed heater sealing material after heat treatment, and as a result, the manufacturing process can be greatly simplified.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

A heating wire 2 made of a coiled nichrome wire with terminal rods 1 at both ends is prepared, this heating wire 2 is inserted into the center of a metal pipe 3 made of 5US304, and the heating wire 2 is made of magnesia powder added with silicone resin. Electrical insulation powder 4 was filled.

After this filling is completed, both ends of the metal pipe 30 are sealed using the sheathed heater sealing material 5 of the present invention, which is made of inorganic fiber paper mainly composed of alumina fibers, as shown in FIGS. 1 and 2. , then perform rolling diameter reduction, and then 250°
A water repellent treatment was performed for 1 hour using C, and 10 sheathed heaters shown in FIG. 3 were completed, and the sample numbers were designated as 11 to 2Q.

On the other hand, for comparison, 10 sheathed heaters were completed in the same manner as described above using a conventional sealing sheet for sheathed heaters made of cardboard, and the sample number was 10.

In addition, after the heat treatment by water repellent treatment at 250° C. for 1 hour, the sheathed heater sealing material 5 was not particularly removed by air blowing or the like for any of the sheathed heaters.

We measured the electrical characteristics of the completed sheathed heater,
The results are shown in the table below.

(Left below) As is clear from the table, in the sheathed heaters of sample numbers 1 to 10 using the conventional sheathed heater sealing material 5 made of cardboard, the withstand voltage is 1000V or less, and the insulation resistance is 200MΩ or less. Unfortunately, it couldn't withstand actual use as it was.

However, in the sheathed heaters of sample numbers 11 to 2o using the sealing material 5 for sheathed heaters of the present invention made of inorganic fiber paper containing alumina fiber as a main component, the withstand voltage was 260.
It exhibited very excellent electrical properties, with an insulation resistance of 0 V or more and an insulation resistance of 2000 MΩ or more.

In this way, by using inorganic fiber paper whose main component is alumina fiber, which is extremely resistant to carbonization, as a sealing material for sheathed heaters, it can be used as a sealing material for sheathed heaters. It becomes possible to obtain a sheathed heater with excellent electrical characteristics without removing the sealing material for the sheathed heater.

In the examples of the present invention, inorganic fiber paper containing alumina fiber as the main component was used, but the invention is not limited to this, and other inorganic fiber paper or alumina fiber and silica fiber may be used. It may be the main component.

Furthermore, although the heat treatment conditions were 260'C for 1 hour, similar effects can be obtained by other solid solution treatment in a reducing atmosphere of 1000C-1100C.

Effects of the Invention As is clear from the above explanation, according to the present invention, since the sealing material for a sheathed heater is composed of inorganic fiber paper whose main component is at least alumina fiber or silica fiber, rolling diameter reduction is possible. After that, even if a heat treatment process of 200°C or higher is performed, the sealing material for the sheathed heater will not carbonize, and as a result, there is no need to remove the sealing material for the sheathed heater. This simplifies the process.

[Brief explanation of drawings]

FIG. 1 is a front view of a sealing material for a nose heater showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the same sealing material for a nose heater.
FIG. 3 is a sectional view of a sheathed heater employing the same nose heater sealing material. Sealing material for 6...7 heaters.

Claims (1)

[Claims] A sealing material for a sheathed heater, characterized in that it is constructed using inorganic fiber paper containing at least alumina fiber or silica fiber as a main component.