JPH03190025A - Manufacture of vacuum interrupter - Google Patents

Abstract

PURPOSE:To prevent the metal having a low melting point from intruding into the junction interface and improve the junction strength by making electrodes of the copper material including the metal having a low melting point, and making both ends of an insulating cylinder of a copper material, and jointing them with a brazing material mainly composed of Ag and Al. CONSTITUTION:Brazing materials 43, 44 are formed on junction parts of lead bars 12, 22 and electrodes 11, 21 of a fixed side member 1 and a movable side member 2. Brazing materials 42, 47 are also formed on the junction parts of auxiliary members 131, 231 provided on both ends of the insulating part 3 and the members 1, 2. The electrodes 11, 21 are made of the material mainly composed of copper and including the metal having a low melting point, and the members 131, 231 are made of the material mainly composed of copper. The brazing materials 42, 43, 44, 47 are made of an alloy mainly composed of Ag and Al, and they are brazed at a relatively low temperature in non-oxidizing atmosphere, and furthermore, they are heated for exhaust to obtain a vacuum interrupter. The metal having a low melting point is thereby prevented from intruding into the junction interface to improve the junction strength.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for manufacturing a vacuum interrupter, and particularly to a method for manufacturing a vacuum interrupter whose electrodes are mainly composed of copper.

B9 Summary of the Invention The present invention uses a brazing material mainly composed of Ag-Al for the brazing part in the final assembly stage of a vacuum interrupter, and by heating and exhausting it in a vacuum, the brazing strength and airtight seal are improved. The aim is to improve the

C0 Prior Art FIG. 3 is a schematic diagram of a conventional vacuum interrupter of this type.

In the figure, l is a fixed side member, and main members are a lead rod 12 having a fixed electrode 11 at the inner end and a fixed side end plate 13. 2 is a movable member;
The main members are a lead rod 22 having a movable electrode 21 at its inner end, a movable end plate 23, and a bellows 24. 3 is an insulating cylinder made of a member such as ceramics, and 31 is a metal shield provided inside the insulating cylinder.

The vacuum interrupter configured in this way has a movable electrode 21
The electric current is switched on and off by moving up and down in the figure.

A vacuum interrupter having such a configuration is generally manufactured by the following method.

■ As shown in Figure 3, solder metals 41 to 47 made of plate solder and wire solder are placed at the joints of each constituent member and temporarily assembled, and this is placed in a vacuum furnace to perform heating exhaust and brazing at the same time. Vacuum interrupters are manufactured in bulk.

■ Part or all of the fixed side member 1 and the movable side member 2 are manufactured in advance in a previous process, and then brazed in a vacuum with a brazing material 42, 47 interposed between them and the insulating cylinder 3. A vacuum interrupter is manufactured by simultaneously performing heating and evacuation.

In the case of (2) above, the same brazing material (for example, Cu
In the case of (2), it is common to use brazing materials with different melting points (for example, Cu-based and Ag-based).

D0 Problems to be Solved by the Invention Conventionally, in order to satisfy the various characteristics required for vacuum interrupters, electrodes were made of Cu (copper) as a main component, and a low melting point metal such as Bi (bismuth) was added to this by 0.1 It is generally practiced to contain up to 20% by weight.

However, when the electrode contains such a low melting point metal, it is known that a part of the low melting point metal evaporates from the electrode at the temperature (700 to 1000° C.) during brazing. This evaporated metal not only adheres to the internal materials of the vacuum container, but also partially enters the molten solder and may adversely affect the brazing joint.

Although the degree of such adverse effects is partly related to the content of low-melting point metals, the hermetic seal joints are particularly problematic.

In other words, even if the mechanical bonding strength is sufficient, there is a risk that the hermetic sealing bond may be insufficient.

Such hermetic seal joints correspond to the brazing metal positions 41, 42, 45, 46, and 47 in Fig. 3 mentioned above. This applies to all of these brazing metal locations.

■If the fixed side and movable side members are manufactured in advance in the previous process and then integrated in the next process, the brazing material part 42.47 corresponds to this.

91 Means for Solving the Problems As a result of various experiments, the inventors found that if Cu (copper) members are joined together using a brazing material made of Ag and Al, a low melting point metal is added to the brazed part. It has been found that airtight brazing can be achieved without any intrusion. In other words, it has been found that reliable brazing can be achieved by using Ag-Al brazing material to braze and join Cu or components mainly composed of Cu in a vacuum interrupter. In addition, when a material that forms a eutectic with Ag or Al is added, Ag.

It has also been found that the Al diffusion layer can be stabilized and the bonding can be made more reliable.

In other words, the existence of a diffusion layer of Ag and Al in the brazed area effectively prevents these metals from entering the brazed joint interface, even if the electrodes and other components contain low-melting point metals that are difficult to evaporate. It was found that this can be prevented and stable brazing can be performed.

Therefore, the present invention uses an Ag-Al alloy brazing material as a brazing material for joining Cu members together in a vacuum interrupter.

(1) The composition of the Ag-Alo material is 50 to 80% by weight of Ag and 20 to 50% by weight of Al.

Field C2> In order to prevent Cu (copper) from being eaten away, it is preferable to add Cu that forms a eutectic with either Ag or Al. In this case, the composition is 25 to 80% by weight of Ag.
, Al is 14 to 75% by weight, and Cu is 14 to 30% by weight. Desirably, Ag is 30 to 58% by weight and Al is 2% by weight.
6 to 60% by weight, and Cu is 10 to 25% by weight.

However, Ag, Al, and Cu are outside the above range (less than,
In the case of (and exceeding), the characteristics of each component become remarkable, and the brazing properties and bonding properties sharply deteriorate.

(3) As the low melting point metal, for example, Bi (bismuth)
, Sb (antimony), and other low melting point metals that are added to improve welding resistance and severability.

(4) The conditions for using the brazing material are Ag-Al or A
Approximately 650°C, which is higher than the eutectic point temperature of g-Al-ICu
This is also desirable from the viewpoint of reducing evaporation and scattering of low melting point metals.

(5) When integrating a vacuum interrupter, (1) a fixed side member and a movable side member are formed separately, and these are integrated with an insulating cylinder.

■When one of the fixed side member and the movable side member is integrated with the insulating cylinder in advance, and then the whole is integrated.

Any of the following applies.

(6) The electrode may be brazed to the lead rod in advance in the previous step. Furthermore, in the case of joining an electrode with a low content of low melting point metal and a lead rod, instead of the Ag-A10 material used in the present invention, the conventionally commonly used Cu-Mn-
A brazing material such as Ni may also be used. However, it is desirable to use the AgAt brazing material used in the present invention.

(7) In the present invention, the joint portion may be made of Cu;
The entire member does not need to be made of Cu or a material containing Cu as a main component.

F9 action The existence of a diffusion layer of Ag and Al in the brazed joint of Cu members can effectively prevent low melting point metals from entering the joint interface, and even if the electrode contains low melting point metals, the vacuum The brazing joint strength and airtight seal joint of the interrupter can be ensured and highly reliable.

G. Example The present invention will be explained in detail based on the following examples.

First, we will explain the results of experiments that investigated the properties of brazing filler metal.

(Experimental Example-■) This is an example of joining a metal member containing a low melting point metal and oxygen-free steel, which is composed of 50% by weight of Cu, 40% by weight of Cr, and 10% by weight of Bi.

(a) For parts containing low melting point metals: Approximately 160 g of Cr (chromium) powder with a particle size of 100 mesh is placed in an alumina container (inner diameter 68 m11), and Cu powder is placed on top of this Cr powder.
- B1 alloy (approximately 400 g) is placed, the container is covered with a lid, and the container is degassed and heat treated at a temperature below the melting point of the Cu-B1 alloy in a vacuum furnace to first diffuse bond the Cr particles. to form a porous infiltration matrix.

Thereafter, the temperature is raised to infiltrate Cu and Bi into the infiltration base material.

At this time, the inside of the alumina container becomes an atmosphere containing Bi vapor, and a composite metal containing a large amount of Bi is obtained.

The metal material thus obtained is removed from the container and its outer surface is machined into a predetermined size and shape.

(b) About the brazing material ■ The Ag-A component ratio is approximately Ag + Al = 70: 30 (wt%)
Weighed so that the particle size is 325 mesh or less (-
325 mesh) Ag powder (140g) and Al powder (
60g) and thoroughly mix these powders with a mixer. From the resulting mixed powder approx. , 5 g was taken out, filled uniformly into a mold with a diameter of 40xx, and pressure-molded at 30 tons to obtain a circular thin plate-shaped brazing material with a thickness of 0.411 mm.

■ The Ag-Al-Cu brazing material component ratio is approximately Ag:Al:Cu=40:40:20 (
Ag powder (80 g) with a particle size of 325 mesh or less (-325 mesh) and Al
A powder (160 g) and a Cu powder (40 g) are prepared, and these powders are thoroughly mixed with a mixer.

Approximately 1.5 g was collected from the obtained mixed powder, and the diameter was 4011.
The mixture was uniformly filled into a mold of No. 1 and press-molded at 30 tons to obtain a circular thin plate-shaped brazing material with a thickness of 0.4 mm.

(c) About brazing The brazing materials (Ag-Al and Ag-Al-Cu) are placed between the Cu-Cr-B1 alloy member and the member made of oxygen-free copper, and these are placed in an alumina container. It was placed, covered, and heat-treated in a vacuum furnace (650° C., 15 minutes) to bond.

(d) Results of brazing It was confirmed that the bonded product obtained as described above was firmly bonded, and that the brazing material was sufficiently fluid.

In addition, when observing the cross section of the joint with an X-ray microanalyzer, it was found that the diffusion layer of Ag and Al (and Cu)
It was confirmed that precipitation of Bi at the interface was prevented and a stable brazed bonding layer was formed.

(Comparative Experimental Example) For comparison, commonly known Ag-Cu-1n
Brazing was attempted using a Cu-Mn-Ni-based brazing material and a Cu-Mn-Ni-based brazing material, with the temperature conditions being 800°C for the former and 950°C for the latter, and the other conditions being the same as in Example-1 above. , both peeled off and could not be brazed.

(One Example) From the above results, it was found that a brazing material containing Ag-Al can provide sufficient bonding strength even when directly bonding a Cu member containing a low melting point metal. A vacuum interrupter shown in FIG. 1 was constructed using this brazing material.

That is, when constructing the vacuum interrupter shown in FIG. 1, first, the fixed side member 2 shown in FIG. 2(a) and the movable side member 2 shown in FIG. 2(b) are formed in a pre-process.

The fixed side member l includes a fixed side end plate 13 made of Cu (copper),
A lead rod 12 made of Cu, an exhaust pipe 14 made of Cu,
Between each of these members, 35Cu-3
A brazing material (plate brazing material, linear brazing material) consisting of 5Ti-30Al (wt%) is arranged and temporarily assembled, and heated to a temperature of approximately 980°C in a non-oxidizing atmosphere (vacuum). to form a bond.

Moreover, the movable side member 2 includes a fixed side end plate 23 made of Cu,
A lead rod 22.5 made of Cu (stainless steel) is made of bellows 24, and between each of these members,
A Cu--Mn--Ni brazing material is placed and temporarily assembled, and a bond is formed by heating to a temperature of about 1000° C. in a non-oxidizing atmosphere (vacuum).

Fixed side member l and movable side member 2 formed in advance as described above
As shown in FIG. , Bi is 10
% by weight) and temporarily assemble. Also, C at both ends.
They are temporarily assembled to the insulating tube 3 provided with auxiliary members 131 and 231 made of u (copper) via brazing materials 42 and 47 (plate-shaped soldering materials), respectively.

These brazing materials (42, 43, 44, 47) are 70Ag
-30Al (wt%), in a non-oxidizing atmosphere (vacuum) at a temperature lower than the brazing temperature in the previous process, approximately 650°C
A predetermined vacuum interrupter is integrally constructed by brazing and joining, and the desired vacuum interrupter is obtained by heating and exhausting.

In the vacuum interrupter thus formed, the electrodes 11.21 and the lead rods 12, 22 are joined, and the end plate 1
3.23 and the auxiliary fittings 131, 231 are firmly joined. In particular, the end plate 13.23 and the auxiliary fittings 131, 231
As a result of investigating the joint with the Helilum leak detector, it was confirmed that there was no leakage at all.

Note that the brazing material of Cu-Mn-Ni, which has been commonly used in the past, was used between the bellows, the lead rod, and the end plate in the AKA I (Ag-A I-
This is due to the fact that SUS brazing is not stable with Cu), and when configuring the movable side member 2 with the above-mentioned configuration, this brazing material part will not be adversely affected by Bi. This is because there are almost none.

Effects of the H0 Invention Since the present invention uses a brazing material mainly composed of Ag and Al, a diffusion layer of Ag and Al is formed in the brazed part, and this diffusion layer flows to the bonding interface of low melting point metals. Even if the electrode contains a low melting point metal (
0.1 to 20% by weight), the electrode and lead rod can be reliably bonded.

Moreover, even if the low melting point metal evaporated into the airtight seal joint part is scattered, it will not invade the brazed joint, making it possible to ensure the strength of the airtight seal joint.

Moreover, when Cu is added, which forms a eutectic with Ag and Al, Cu
The phenomenon of members being eaten away can be effectively prevented, and brazing joints can be performed more stably.

Further, since the brazing material has a relatively low brazing temperature of about 650° C., the thermal influence on the joining member and other constituent members can be reduced.

Therefore, the reliability and durability of the vacuum interrupter can be improved, contributing to quality improvement.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a vacuum interrupter according to an embodiment of the present invention, FIGS. 2(a) and (b) are partial assembly diagrams of the vacuum interrupter in FIG. 1, and FIG. 3 is a conventional vacuum interrupter. FIG. 2 is a schematic configuration diagram of an interrupter. l... Fixed side member, 2... Movable side member, 42, 43
゜44.47・・・Brazing material. 2 outside officers and 1 standing officer

Claims (2)

[Claims] (1) A fixed side member including at least a lead rod and an end plate, a movable side member including at least a lead rod and a bellows, an insulating cylinder to which the end plates of these members are hermetically joined, and each lead rod. A method for manufacturing a vacuum interrupter whose main component is an electrode provided at an inner end, including a first step of forming the fixed side member and the movable side member in advance, and insulating the formed fixed side member and the movable side member. The second step is to assemble a vacuum interrupter by brazing and joining an electrode to the inner end of the lead rod, and heating and evacuating it in a vacuum to obtain a vacuum interrupter. Formed from a material whose main component is
At least the end portion of the member to be the brazed portion in the second step is formed of a material containing copper as a main component, and a brazing material containing Ag and Al as main components is used for at least the airtight joint in the second step. A method for manufacturing a vacuum interrupter characterized by: (2) The method for manufacturing a vacuum interrupter according to claim 1, characterized in that in the first step, at least one of the electrodes is brazed to the inner end of the lead rod.