JPS589061B2 - Glass Compound Niyor Fuushihouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing method in which a portion of an object to be sealed is sealed with a glass compound.

Conventionally, in the manufacture of a sealed object, such as a sheathed heater, the end of a metal protection tube housing an electric heating element is sealed with silicone rubber, silicone varnish, epoxy resin, glass, or the like.

This product has the drawback that the airtightness and mechanical strength of the closed portion are insufficient, and the closed portion tends to deteriorate, crack, and peel due to long-term use.

Therefore, the inventor of the present invention considered sealing the end of the tube with a glass compound such as Micalex (trade name) manufactured by Tokyo Shibaura Electric Co., Ltd.

Although this product has the advantage of overcoming the drawbacks of the prior art described above, it has been found that the manufacturing process is complicated and requires a lot of labor.

That is, in mica glass sealing, mica powder and glass powder are mixed in a predetermined ratio, for example, 4 to 6 of the former to 6 of the latter.
The mixture is mixed at a weight ratio of 1 to 4, and a small amount of water is added to the kneaded mixture, which is then filled into the end of the tube, dried thoroughly, and then hot pressed at a temperature above the melting point of glass to close the end of the tube. It is something to do.

In this way, micarex sealing is not a blur that is difficult to work with, but due to the pressure difference with the inside of the protective tube during hot pressing,
Air-tight sealing is difficult due to the formation of air bubbles or pores within the compound or between it and the protective tube.

The present invention was made based on the above circumstances, and it is an object of the present invention to provide a sealing method using glass compound that is easy to manufacture, saves labor, is easy to hermetically seal, and is free from cracks and peeling. The purpose and gist of the object is to fill the part of the object to be sealed with a high melting point powder, then supply bonding glass to the part to be sealed, and in a molten state, add the high melting point powder to the part to be sealed. The powder is infiltrated to form a glass compound, and the glass compound is welded to the area to be sealed to seal it.

The details of the invention will be explained below with reference to the illustrated embodiments.

The figures show, in order of steps, a method for sealing the tube end of a sheathed heater to which the present invention is applied.

First, as shown in the first diagram, the outer diameter is 10 mm and the wall thickness is 0.5 m.
m of sealed body, that is, a mild steel protective tube 1, with a diameter of 2 nm.
A nichrome wire heating element 3 connected to the tip of a rod-shaped terminal 2 made of mild steel is arranged approximately along the center line of the protective tube 1, and the terminal 2 is connected to the center of the portion 4 to be sealed at the end of the protective tube 1. Penetrate along the line.

Next, electrically insulating high melting point powder 5, for example, 40 to 200 mesh molten magnesium oxide powder, is filled in the protective tube 1 without any gaps to fix the heating element 3, and the end edge of the protective tube 1 is fixed. It is located at a portion slightly closer to the center than the scheduled sealing portion 4, that is, the end surface.

Next, as shown in the second figure, a suitable amount of bonding glass powder 6, for example B20s-S1
02-BaO glass (thermal expansion coefficient 107X10-7/'
Filled with powder with a softening point of 581°C.

Next, as shown in the third figure, the outer surface of the portion 4 to be sealed of the protection tube 1 is heated to about 800° C. with burners 7, 7.

Then, the part to be sealed 4 is heated, and the heat is transferred to the high melting point powder 5 and the bonded glass powder 6 in the part to be sealed 4.
conducts and heats.

As a result, the bonded glass powder 6 melts and gradually penetrates into the high melting point powder 5, expels the air existing between the powder 6, fills the powder 6, and welds to the particles of the powder 6. It is welded to the inner surface of the portion to be sealed 4 and the terminal 2.

After about 3 minutes, a part of the bonded glass 6 becomes a high melting point powder 5.
When a thin layer 6' of less than 1 mm remains on the surface, the burners 7, 7 are removed and allowed to cool.

Then, as shown in FIG. 4, the high melting point powder 5 in the sealing portion 4 of the protection tube 1 is hermetically bonded with the bonding glass 6 to form a glass compound 8 having a desired thickness, for example, 5 mm.
A part of the bonding glass 6 of this compound 8 is hermetically welded to the inner surface of the part 4 to be sealed and the terminal 2, and is also coated with a thin layer on the surface of the glass compound 8, so that the part to be sealed is sealed. Section 4 is hermetically sealed and electrically insulated.

The terminals of the sheathed heater are usually taken out from both ends of the protection tube, and once one end is sealed, the other end is sealed in the same way, thereby completely sealing the sheathed heater.

This sealing is done by infiltrating the bonded glass liquid between the particles of the high melting point powder, so even if there is a slight difference in the outside air between the inside and outside of the sheathed heater, it can be reliably sealed, and the internal pressure of the sheathed heater can be reduced during sealing. It was found that lowering the temperature by several mmHg was effective.

The glass compound 8 formed in this way does not contain bubbles and is highly airtight, has improved heat resistance, is resistant to thermal and mechanical shock, and has a different coefficient of thermal expansion from the protective tube 1. It also withstands distortion well and does not cause peeling or cracking.

Therefore, this sealing structure is completely hermetically sealed, durable, and thermally and mechanically robust.

Furthermore, this method requires only filling the high melting point powder 5 into the protective tube 1, filling it with the bonding glass powder 6, and heating it, so sealing does not require special equipment and requires special skill. It does not require much labor or effort, and therefore can be manufactured at low cost.

Note that after filling the high melting point powder 5 in the above-described method, the bonding glass powder 6 may be gradually supplied while heating the portion 4 to be sealed.

It is necessary to adjust the amount of bonding glass powder 4 so that the obtained glass compound 8 has an appropriate thickness; if it is too thin, the mechanical strength will be insufficient.

In addition, the glass thin layer 6' on the surface of the glass conbound 8 is 1
If the thickness exceeds 1 mm, it will easily peel off, so it is necessary to adjust the heating temperature and heating time appropriately so that the thickness of the thin glass layer 6' is 1 mm or less.

In addition, although the bonding glass was supplied in the form of powder in the above embodiments, the present invention is not limited to this. For example, after filling a high melting point powder, the portion to be sealed is filled with molten bonding glass that is heated to a low viscosity. The bonding glass may be welded to the surface of the high melting point powder layer by infiltrating into the high melting point powder, and then heated to infiltrate the bonding glass into the high melting point powder.

In addition, after filling the high melting point powder, the area to be sealed is heated,
Injecting molten bonding glass allows the bonding glass to be supplied and penetrated at the same time.

Furthermore, in the present invention, the high melting point powder is formed into a pellet by binding powder such as magnesium oxide, aluminum oxide, or miryoku with a binder, and the pellet is filled into the area to be sealed. It's okay.

Furthermore, although the above-mentioned embodiment described the tube end sealing of a sheathed heater, the present invention is not limited to this, but can be applied to sealing of all objects to be sealed, and has similar effects. If electrical insulation is not required, the high melting point powder does not necessarily have to be electrically insulating.

Furthermore, depending on the application purpose, the high melting point powder does not necessarily need to be filled into the entire object to be sealed; for example, it may be filled only into the part of the object to be sealed, and the entire filled powder may be formed into a glass compound. It's okay.

There are no restrictions on the shape and material of the sealed body.

As described in detail above, the present invention fills the high melting point powder into the part to be sealed of the object to be sealed, then supplies the bonding glass to the part to be sealed, and melts the glass into the high melting point powder. Since it is formed into a glass compound by penetrating the powder and is welded to the area to be sealed, it is easy to manufacture and saves labor, and it is easy to seal hermetically and there is no risk of cracking or peeling. We can provide a sealing method using a strong and durable glass compound.

[Brief explanation of drawings]

1 to 4 are explanatory diagrams illustrating one embodiment of the sealing method using a glass pound of the present invention in the order of steps. 1... Body to be sealed, 4... Part to be sealed,
5... High melting point powder, 6... Bonded glass, 8... Glass combined.

Claims (1)

[Claims] 1 Filling a portion of the object to be sealed with high melting point powder, then supplying bonding glass to the portion to be sealed, and infiltrating this glass in a molten state into the high melting point powder to form a glass compound. A method of sealing using a glass compound, characterized in that the glass compound is sealed by welding to the portion to be sealed.