JPS6167565A - Joining method of ceramics pipe and metallic pipe - Google Patents

Abstract

PURPOSE:To prevent ceramics from being damaged, by using a metallic bellows as an intermediate joint. CONSTITUTION:A ceramics pipe 1 consisting of alumina, silica, etc. and a metallic pipe 2 of a stainless steel pipe, etc. are joined by using a metallic bellows 3 as a joint between them. That is to say, the end part of the ceramics pipe 1 is joined to one end 4 of the metallic bellows 3, and the end part of the metallic pipe 2 is joined to the other end 5. The ceramics pipe 1 and the metallic bellows 3 are joined by a vacuum brazing method, etc., and the end part of the ceramics pipe 1 is brought to metallized processing. Also, the metallic pipe 2 and the bellows 3 are joined by TIG welding, etc. According to this method, a distortion force of the joint of the ceramics pipe 1 and the metallic pipe 2 is absorbed by deformation of the bellows 3, and damage of the ceramics can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a method for joining a ceramic tube and a metal tube.

(Prior Art and Problems to be Solved) Ceramic tubes and metal tubes are increasingly being used in conjunction with each other in piping and the like that require partial heat resistance. In such cases, conventionally the ceramic tube 12 and the metal tube 14 have been brazed directly in a vacuum as shown in Figure 2, but since ceramics are brittle, brazing may occur due to differences in heat and expansion. Connections are prone to damage due to strain forces. On the other hand, as shown in FIG.
3, the joint 15 of the umbrella-shaped thin metal plate 11b and the metal tube 14 is joined by vacuum brazing as before, and is opposite to this.
For example, in TIG welding, plasma welding is performed, and the umbrella-shaped metal thin Fj, lla and 11b are brought into contact with each other at their peripheral edges 16, and an expansion pipe joint that is TIG or plasma welded is used to connect a ceramic pipe and a metal pipe. A method has been proposed to provide a helical joint between thin plates, but it is technically difficult to weld helical joints of thin plates.
In particular, in the case of aluminum thin plates, it is even more difficult to obtain a welded part with high airtightness.

Furthermore, in order to avoid heat load on the ceramic pipe, this type of expansion pipe joint requires a long flange that extends outward from the pipe periphery, making it suitable for piping with severe spatial restrictions around the pipe. There are problems such as difficulty.

It is an object of the present invention to solve the above-mentioned problems and provide a joining method that causes less damage due to stress.

(Means for solving problems) The present invention uses a metal bellows as an intermediate joint in a method of joining a ceramic tube and a metal tube,
The present invention relates to a method for joining a ceramic tube and a metal tube, characterized in that a ceramic tube is joined to one end of the ceramic tube and a metal tube is joined to the other end.

The present invention will now be described in detail with reference to FIG. 1 of the accompanying drawings. A metal bellows 3 is jointed between the ceramic tube 1 and the metal tube 2, the end of the ceramic tube 1 is joined to one end 4 of the metal bellows, and the end of the metal tube 2 is connected to the other end 5 of the metal bellows 3. Join. It is convenient to make the end portion 5 of the metal bellows thicker because it facilitates welding.

That is, in this case, the reliability of the joint can be improved by employing, for example, an automatic welding method.

As the ceramic tube, a ceramic such as alumina or silica is used to ensure electrical insulation, corrosion resistance, or a uniform magnetic field, and as the metal tube, a stainless steel tube, an aluminum tube, or a steel tube is used.

Also, the metal bellows used as a joint is usually made of the same material as the gold mud pipe, but depending on the purpose, the combination of the metal pipe and the bellows can be made of stainless steel and Kovar, copper and brass, or titanium. Can be used in combination with stainless steel, etc.

The ceramic tube and the metal bellows are preferably joined by a conventional vacuum brazing method, and the joining end of the ceramic tube is preferably subjected to a customary metallization treatment to facilitate the joining. However, the joining of the ceramic tube and the metal bellows is not limited to brazing, and any other suitable method may be used, such as diffusion bonding, as long as it can prevent damage to the joint.

A known welding method such as 770 can be used to weld the metal pipe and the metal bellows.

It is desirable for the metal bellows to have a thin plate and a large number of ridges to increase the distance to the ceramic tube, so as to minimize the conduction of welding heat to the ceramic tube.

(Example) Next, an example will be described.

Aluminum (JISA30
Regarding the case of using bellows manufactured by 04), the joint end of the alumina tube is metallized as usual, and then an aluminum plating sheet is used as the soldering material, and the bellows is heated in an atmosphere of reduced pressure to about 1 Torr.
The alumina tube and aluminum bellows were joined together by heating to 0.5°C, and then cooled to room temperature. The aluminum bellows and aluminum tube were conventionally welded by TIG welding.

A vacuum leak test was conducted on the joint, and there was no leak, and good results were obtained when applied to the vacuum piping of an electron accelerator.

(Effects) As described above, according to the method of the present invention, there is no distortion caused by the difference in thermal expansion coefficients that occurs when the ceramic tube and the metal tube are directly brazed, and the ceramic tube and the metal tube are The strain force caused by the connection with the metal bellows is absorbed by the deformation of the metal bellows, that is, the bellows-type expansion joint, and damage to the ceramic can be prevented.

General welding can be applied to join the metal pipe and metal bellows, and automatic welding can prevent defects such as leaks and increase the reliability of the joint. Also, by making the metal bellows thin and having a sufficiently large number of threads, the shadow K of welding heat can be prevented. Moreover, since the metal rose is used as an expansion pipe joint, the shape of the connection part is WJ.
Since it is simple and has no protruding parts, it has extremely great practical effects, such as allowing piping to be installed in narrow spaces.

[Brief Description of the Drawings] Fig. 1 is a partially fragmented front view showing a state of joining by the method of the present invention, Fig. 2 is a sectional view showing a state of joining by conventional brazing of a ceramic pipe and a metal pipe, FIG. 3 is a partially exploded front view showing a state in which a conventional expansion pipe joint made of a thin metal plate is interposed between the joints. 1...Ceramics tube, 2...Metal tube, 3...Metal herwels, 4...Ceramics pipe joint end of metal bellows, 5...Metal pipe joint end of metal herwels, applicant's agent Patent Attorney Kamoshi 1) Second son Figure 2 Figure 3 Figure 1

Claims (1)

[Claims] A method for joining a ceramic tube and a metal tube, the method comprising using a metal bellows as an intermediate joint, and joining a ceramic tube to one end of the bellows and a metal tube to the other end.