JPH0410321A - Manufacture of vacuum interrupter - Google Patents

Abstract

PURPOSE:To reduce the area to be exposed in a vacuum to restrict evaporation of metal having a low melting point from electrodes by forming a pair of electrodes so as to abut on each other at the time of brazing. CONSTITUTION:A fixed side member 1, a movable side member 2, an insulating cylinder 3, and electrodes 11, 21 are assembled temporarily through wax materials 41-44. This temporarily assembled member is positioned in a vacuum furnace so that the fixed side member 1 is positioned in the lower side, and a pair of electrodes are made to abut on each other by dead-weight of the movable side member 2, and exhaust and brazing are performed simultaneously under this condition. Bonding of the electrodes 11, 21 and lead bars 12, 22 and bonding of end plates 13, 23 and auxiliary fitting 31, 36 are performed firmly. The exposed area in a vacuum is reduced by making a pair of electrodes to abut on each other, and evaporation of metal having a low melting point is restricted effectively.

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 contain a low melting point metal.

B. Summary of the Invention The present invention provides a vacuum interrupter whose electrodes contain a low melting point metal, which is produced by brazing a pair of electrodes against each other in a vacuum and evacuating. This prevents the evaporation and scattering of the solder, and improves the brazing strength and airtight joint.

C9 Prior Art FIGS. 3 to 5 are schematic diagrams of the conventional vacuum interrupter.

In the figure, ■ is a stationary side member, which is composed of a lead rod I2 having a stationary electrode 11 at its inner end and a stationary side end plate 13 as main members. 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, 3a and 3b are sealing fittings provided at the ends of the insulating cylinder, and 31
is a metal shield provided inside the insulating tube.

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.

There are various ways to manufacture a vacuum interrupter having such a structure, but especially when the electrode contains a low melting point metal, it is usually manufactured by the following method.

That is, the fixed side member l and the movable side member 2 are manufactured in advance in the previous process, and the brazing material 41 is placed between the insulating cylinder 3 and the fixed side member l and the movable side member 2.
interposed between the pair of electrodes, brazing in a vacuum at a relatively low temperature (about 700°C) with the gap between the pair of electrodes, and then evacuation through the exhaust pipe 14 to produce a vacuum interrupter. There is.

D1 Problems to be Solved by the Invention Conventionally, in order to satisfy the various characteristics required for vacuum interrupters, electrodes generally contain 0.1 to 20% by weight of a low melting point metal, such as Bi (bismuth). It is being done.

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. For this reason, ■ The manufacturing of vacuum interrupters equipped with electrodes containing low-melting point metals improves productivity because each component of the vacuum interrupter is formed by brazing and then vacuumed as described above. was bad.

Moreover, since it contains a low melting point metal, it has the following problems.

(2) Bi, which is a component of the electrode, evaporates and scatters at the brazing heating temperature, making it impossible to reliably obtain the desired performance of welding resistance and low cutting current characteristics.

(2) This evaporated metal not only adheres to the internal materials of the vacuum container, but some of it also enters the brazed joints and has no adverse effect, which poses a problem.

Although the degree of this adverse effect is partly related to the content of low-melting point metals, it is especially problematic at hermetic seal joints.

In other words, even if the mechanical bonding strength is sufficient, there is a risk that the bonding will be insufficient as an airtight seal.

An example of such an airtight seal joint is the final airtight joint, such as the brazing material portion 4I in FIG. 3 described above.

E8 Means for Solving Problem The inventors conducted various experiments and found that by keeping a pair of electrodes against each other during brazing, the exposed area in vacuum is minimized and Bi is removed from the electrodes. We tried to see if we could suppress evaporation and scattering.

As a result, the results shown in FIG. 2 were obtained.

In Figure 2, the vertical axis shows the evaporation amount of Bi (wt%), the horizontal axis shows the heating temperature (°C), the 〇-〇 line shows the case where a pair of electrodes are butted against each other, and the ... line shows the case where a pair of electrodes are butted against each other. This is the case when the electrodes are spaced apart (conventional method).

That is, it was found that when a pair of electrodes are butted against each other, the evaporation of Bi is almost slight at a heating temperature of about 800°C, and begins to increase slightly from about 900°C.

On the other hand, when there is a gap between a pair of electrodes as in the conventional case,
It has become clear that the temperature increases rapidly from around 700°C.

Therefore, in the present invention, when the electrodes contain a low melting point metal, a vacuum interrupter is manufactured by brazing a pair of electrodes against each other in a vacuum and evacuating the electrodes.

In addition, as the (+) low melting point metal, for example, Bi (bismuth)
, Sb (antimony), and other metals that are well known as low melting point metals.

(2) The abutting force between the pair of electrodes may be small; for example, a pressing force of about the same force as the movable member's own weight with the movable member facing upward may be sufficient.

(3) To integrate the vacuum interrupter by brazing, ■ Form the fixed side member and the movable side member separately, and integrate these with the insulating cylinder, and at the same time, solder join the electrode and lead rod in vacuum. and when heating and exhausting is performed.

(2) When one of the fixed side member and the movable side member and the insulating cylinder are integrated in advance, and then, at the same time as the whole is integrated, the electrode lead rod is soldered in a vacuum, and the heat exhaust is performed.

■ When each component is brazed and joined in a vacuum and heated and evacuated.

Any of the following applies.

In addition, in the case of ■2■, the brazing material in the post-process is kept at a temperature of about 800°C, which is a temperature at which the evaporation and scattering of low-melting point metals does not become active.
It is most desirable to use a brazing material that can be brazed at a temperature below.

F9 action Since the pair of electrodes are butted against each other, the area exposed to the vacuum is reduced, and as a result, the evaporation and scattering of the low melting point metal is effectively suppressed.

Therefore, the adverse effect on the hermetic brazing material is improved, the electrode performance can be maintained at the target value, and a highly reliable vacuum interrupter can be obtained.

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

In the figure, reference numeral 1 denotes a stationary side member, which consists of a lead rod 12 and a stationary side end plate 13 as main members, and is formed in advance in a previous process.

2 is a movable side member, which includes a lead rod 22 and a movable side end plate 2.
3 and a bellows 24 as the main members, which are formed in advance in a previous step.

3 is an insulating cylinder made of a member such as ceramics, and 3a
, 3b is a sealing fitting provided at the end of the insulating tube, and 31 is a metal shield provided inside the insulating tube.

The brazing material used to form each of these members is, for example, Cu-Mn-Ni, and the brazing temperature is approximately 1000
'C.

41, 42, 43, and 44 are brazing materials, respectively, and the fixed side member 1, movable side member 2, insulating cylinder 3, and electrodes 11, 21 are temporarily assembled via these brazing materials.

Then, the fixed side member 1 is placed in a vacuum furnace with the lower side, and the pair of electrodes are brought into contact with each other by the weight of the movable side member 2, and in this state, evacuation and brazing are simultaneously performed to manufacture a vacuum interrupter.

These brazing materials are, for example, AgCu-In.

A brazing material such as Cu-In, which requires a relatively low brazing temperature of about 700° C., was used. Further, the electrode is composed of components of 50% by weight of Cu, 40% by weight of Cr, and 10% by weight of Bi.

In the vacuum interrupter thus formed, the electrode 11.21 and the lead rod 12.22 are joined, and the end plate 1
3, 23 and the auxiliary metal fittings 3a, 3b are firmly joined. In particular, the joints between the end plates 13 and 23 and the auxiliary fittings 3a and 3b were investigated using a helium leak detector, and it was confirmed that there was no leakage at all.

H3 Effects of the Invention In the manufacturing method of the present invention, a pair of electrodes containing a low melting point metal are brazed in abutted state, so that the surface area of the electrodes exposed in vacuum can be reduced accordingly.

Therefore, the amount of low melting point metal that evaporates and scatters can be suppressed, and the intrusion of low melting point metal into the brazed part can therefore be suppressed.
) Also in a vacuum interrupter equipped with an electrode, it is possible to ensure a reliable and stable hermetic seal connection.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a vacuum interrupter according to an embodiment of the present invention, FIG. 2 is a relationship diagram between heating temperature and Bi evaporation amount, and FIG. 3 is a schematic configuration diagram of a conventional vacuum interrupter. 4 and 5 are partially assembled configuration diagrams of a conventional vacuum interrupter. l... Fixed side member, 2... Movable side member, 3... Insulating cylinder, 41.42, 43.44... Brazing material. Figure 1 back ratio ° J/) To the drug bribery class map Karo east to jL ha (and B1 Koshi Wabi 1 anlffil east exit 2 people ka 0 舛; 1 - skin ('C1

Claims (1)

[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. In a method for manufacturing a vacuum interrupter whose main components include an electrode containing a low melting point metal provided at the inner end, the pair of electrodes are held in abutted state and each component is joined by brazing. A method for manufacturing a vacuum interrupter, characterized in that: