JPS59100889A - Insulating flange joint - 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 The present invention relates to an insulating flange joint, for example, an insulating flange joint suitable for use in a joint between a vacuum pump boat and a vacuum pump of a nuclear fusion device.

For example, in a tokamak type nuclear fusion device, a high magnetic field is used to stably confine plasma within a vacuum vessel. In order to form this high magnetic field, two mutually perpendicular magnetic field coils, that is, a toroidal magnetic field coil and a boroidal magnetic field coil, are arranged around the torus-shaped container.

The plasma confined within the container by these coil magnetic fields is required to have high temperature and high density in order to cause nuclear fusion. For this reason, it is necessary to exhaust impurities other than the fusion fuel inside the vessel, so the vessel is baked to remove impurities from the inner wall of the vessel, and the gas inside the vessel is evacuated to avoid contamination of the plasma with impurities. There is.

By the way, at the joint between the exhaust pipe coming out of the exhaust boat on the container side and the manhold on the exhaust pump side, it is necessary to insulate the induced current in the exhaust pipe which is in a high magnetic field and to prevent thermal deformation in the high temperature environment during baking. It is necessary to avoid concentration.

Conventionally, in this joint shown in Fig. 1, a 7-lunge joint was used, in which a disk-shaped flange with a similar coefficient of linear expansion was used as the joining metal 3, and this was brazed to the metal flange 1 on the alumina ceramic 2. This provides insulation and connection to the exhaust pipe at the same time.

However, due to the difference in linear expansion coefficient during exhaust baking,
Adhesion point on metallized layer 4 of alumina ceramics 2,
A difference in thermal expansion occurs between the brazing bonding points of the joining metal 3 and the metal 7 flange 1. As a result, elongation deformation occurs in the bonding metal 3 in the radial direction 7, which may cause yield fracture of the bonding metal 3 or brittle fracture of the sialumina ceramics due to concentration of shear core force at the bonded portion of the metallized layer 4. As a result, the high temperature and vacuum evacuation function will be impaired.

Furthermore, a connection structure for a vacuum vessel having a longer dimension in the axial direction than the diameter has been proposed as in JP-A-54-142496, but this metal plate structure with one end U-shaped (or 7-shaped) As can be seen from the fact that it uses the bellows effect, it is not suitable when the thermal expansion in the radial direction is much larger than that in the axial direction.

The present invention was made in view of the above-mentioned drawbacks, and its purpose is to reduce the thermal stress generated at the joints of mechanical parts, maintain insulation properties and high vacuum, and provide strong insulation 7.
To provide lunge fittings.

The present inventors have confirmed through analysis and experiments that in a joint that connects an insulating member such as ceramics and a metal part through a disk-shaped collar, the insulating member and the metal part are The difference in thermal expansion causes radial deformation of the flange, causing shear failure at the joint between the insulating member and the flange. This is because the radial in-plane rigidity of the plate-shaped brim is high, causing deformation to concentrate at the joint, and for a certain radial deformation,
Since the in-plane bending rigidity is small, if radial deformation is absorbed by bending deformation, concentration of deformation at the joint part of the flange, where the reaction force at the joint part of the collar is small against a certain deformation, can be avoided.

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

Note that the same reference numerals are used for the same parts as in the past.

Embodiment of the present invention In FIG. 2, 1 is a metal 7 flange;
Reference numeral 2 is made of alumina ceramics, and when the metal flanges 1 are joined together, they are electrically insulated from each other. 3 is a cup-shaped bonding metal that has almost the same linear expansion characteristics as the alumina ceramic 2 and has a small modulus of longitudinal elasticity; 4 is the bond between the alumina ceramic 2 and the bonding metal 3; the alumina is made of molybdenum, zirconium, titanium, etc. A metallized layer 5, which is formed by reducing the surface area of the ceramic 20 to form a bonding layer, is a soldering part between the metal flange 1 and the bonding metal 3, and is used together with the metallized wear bonding part 4 for vacuum sealing.

In this embodiment, a cylindrical portion 6 having an appropriate length is formed by bending or the like in advance on the joining metal 3 of the metal flange 1 and the alumina ceramics 2.

In the embodiment shown in FIG. 3, the structure of the bonding metal 3 is as follows:
A circular tube 6' made of the same material is brazed to the outer circumference of a disc-shaped flange bonded to the alumina ceramics 2, and the other end of the core circular tube 6' is brazed to the metal flange 1. A cylindrical portion is formed between the metal flange 1 and the alumina ceramics 2. According to these embodiments, the difference in thermal expansion that occurs in the radial direction between the metal flange 1 and the alumina ceramics 2 is absorbed by the bending deformation of the joined metal cylindrical part 6, and the shear applied to the brazing part 4 at the end of the joined metal is absorbed. It has the effect of relieving stress and allowing the joint to have high strength and be used at high temperatures and high vacuum.

According to the analysis by the present inventors, as shown in FIG. 4, in these embodiments, the effective length of the cylindrical portion is
By making the length between each bonded part between the metal and the alumina ceramic 2 about 2 to 4 times, the stress generated in the bonded metal and the bonded part of the metal and the alumina ceramic can be reduced compared to the conventional structure. It is confirmed that it can be reduced to 1/4 to 115 times.

According to the present invention, when a thermal expansion difference occurs in the insulated connection part, the radial deflection rigidity of the bonded metal is small, and the stress in the bonded part can be reduced at the same time as the metal base material, resulting in high vacuum sealing. It is possible to provide an insulating flange joint that is durable and can be used at high temperatures.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional insulated 7-lunge joint structure, Fig. 2 is a sectional view showing an embodiment of the insulated 7-lunge joint of the present invention, and Fig. 3 is a sectional view showing another embodiment of the present invention. 4 are characteristic diagrams showing the relationship between the cylindrical length of the structure of the present invention and the maximum stress generated in the bonded metal. Engineering: metal flange, 2: alumina ceramics, 3: bonding metal, 4: metallized layer, 5:
Brazing part, 6... Joined metal cylindrical part.

Claims (1)

[Claims] 1. An alumina ceramic having a metallized layer on a part of the surface of the metal flange ends, and a joining metal having one end brazed to the metallized layer of the alumina ceramic and having a coefficient of linear expansion approximately equal to that of the alumina ceramic. An insulated 7-lunge joint that is integrated via a 7-ring insulated joint, characterized in that the joining metal has a cylindrical flange, and an end of the flange is joined to the metal 7-lange. .