JPH042018A - Manufacture of vacuum interrupter - Google Patents

Abstract

PURPOSE:To effectively prevent evaporating and scattering a low melting point metal so as to form a vacuum interrupter in the structure of reliable and stable airtight seal union by using a soldering material consisting chiefly of Au-In. CONSTITUTION:A stationary-side member 1 is composed of a stationary-side end-plate 13, a reed rod 12 and an exhaust tube 14 all made of respectively of Cu, and it is unitedly formed by arranging a soldering material between the respective members to be temporarily assembled and then heating the resultant assembly. A movable-side member 2 is composed of a stationary-side end-plate 23 made of Cu, a reed rod 22 made of Cu and a bellows 24, and it is unitedly formed by arranging the soldering material between the respective members to be temporarily assembled and then heating the resultant assembly. The members 1 and 2 are temporarily assembled together by mounting electrodes (components of Cu, Cr and Bi) 11, 21 respectively onto the inner-end portions of the respective reed rods 12, 22 via respective corresponding soldering-materials 43, 44. Also, the members are temporarily assembled to an insulating cylinder 3 via respective corresponding soldering materials 42, 47. Each of these soldering materials is made of 67 of Au-33 of In(wt.%), and then a desired vacuum interrupter can be obtained by soldering and uniting the members together at a temperature of about 500 deg.C lower than a soldering temperature, heating the resultant unit and at the same time vacuumizing the inside of the unit to exhaust the air thereof via the exhaust tube 14.

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.

B8 Summary of the Invention The present invention provides the use of Au in the airtight port part in the final assembly stage of a vacuum interrupter whose electrodes contain a low melting point metal.
The brazing strength and airtightness are improved by using an axle material containing -In as a main component and by vacuuming after assembly at a brazing temperature of 700° C. or less.

C9 Prior Art FIG. 5 is a schematic diagram of a conventional vacuum interrupter of this type.

In the figure, reference numeral 1 denotes a stationary member, and its main members include a lead rod 12 having a fixed electrode 11 at its inner end, and a stationary 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 5, soldering materials 41 to 47 consisting of plate soldering and wire soldering 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.

■ As shown in Fig. 5, soldering materials 41 to 47 made of sheet soldering and wire soldering are placed at the joints of each constituent member and temporarily assembled, and then brazed in a non-oxidizing atmosphere (for example, a hydrogen atmosphere). After that, the vacuum interrupter is manufactured by heating and exhausting in the atmosphere through an exhaust pipe (not shown).

■ The fixed side member 1 and the movable side member 2 are manufactured in advance in the previous process, and a brazing material 42.47 mm is placed between the insulating cylinder 3
Brazing is performed in a vacuum with the help of Alternatively, a vacuum interrupter is manufactured by vacuuming after brazing.

In addition, in the cases of (1) and (2) above, the same brazing material (for example, Cu-based brazing material) is placed in each location, and in the case of (2), brazing materials with different melting points (for example, Cu-based and Ag-based brazing material) are used. is common.

D0 Problems to be Solved by the Invention Conventionally, in order to satisfy the various characteristics required for vacuum interrupters, it has been common to contain 0.1 to 20% by weight of a low melting point metal, such as Bi (bismuth), in the electrode. 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. This evaporated metal not only adheres to the internal materials of the vacuum container, but also partially enters the molten solder, which poses a problem of adversely affecting 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 parts 41, 42, 45, 46, and 47 in Fig. 4 mentioned above.■ When assembling in a vacuum furnace, This applies to all of these brazing metal locations. Moreover, in the case of batch brazing in a vacuum, the inside of the vacuum interrupter becomes completely hermetically sealed under the high temperature heating state, so there is a problem that evaporated Bj tends to be trapped inside, further deteriorating the airtight joint characteristics.

■ 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.

As a result of various experiments, the inventors focused on the temperature at which evaporation and scattering of Bi becomes active in a metal containing a low melting point metal (eg, Bi).

Figure 4 shows 50Cu-40Cr-10Bf (wt%)
The relationship between the heating temperature (horizontal axis) and weight loss rate (vertical axis) in a metal member with the composition of inert atmosphere (vacuum)
This is what I investigated.

From this figure, it was found that the weight suddenly decreased from around 700°C, that is, the evaporation and scattering of Bi became active from around 700°C. In other words, it was found that when brazing is performed at a temperature of 700° C. or lower, there is almost no evaporation and scattering of Bi, and there is no adverse effect.

(2) Based on the above (2), we have found that if Au-In is used as a brazing material that can be brazed at a temperature of 700° C. or lower, stable brazing bonding can be achieved. That is, Au
-If the brazing material is made of In, there will be no evaporation and scattering of Bi7.
It was found that not only can brazing be performed at temperatures below 00°C, but also that there is an Au-In diffusion layer in the brazing area, which suppresses the intrusion of low-melting point metals into the bonding interface, allowing stable brazing. .

(2) Furthermore, it has been found that the hermetic seal bonding characteristics are more stable if the vacuum interrupter is manufactured by brazing and then evacuating (vacuuming) instead of manufacturing the vacuum interrupter all at once in a vacuum.

Therefore, the present invention uses a brazing material having a composition range shown in FIG.
A wax material made of 6% by weight.

■A brazing material made of 38 to 53% by weight of Au and In.

(2) At a temperature of 500°C or higher, which is the temperature above the eutectic point of Au and In, and at a temperature of 700"C or lower, at which the evaporation and scattering of this low-melting point metal in a metal member containing a low-melting-point metal does not become active. This is a method of brazing at high temperatures.

However, if the proportions of Au and In or the temperature deviate from the above relationships, a stable brazed joint could not be obtained.

(1) 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) Copper is a metal containing a low melting point metal.

Metals with high conductivity such as copper alloy, silver, and silver alloy 1 fall under this category.

(3) It is preferable to mix powders of each component in predetermined amounts and process the brazing material into a predetermined shape so that the characteristics of each component can be utilized.

Further, the desired brazing material can be easily formed by compression molding into a ring shape or disk shape using a mold, or by first compression molding into a plate shape and then using a laser or the like.

Alternatively, an organic binder may be mixed with the mixed powder to form a paste and then applied. In addition, the powder is -
A particle size of 100 mesh or less (149 μm or less) is preferable.

(4) 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.

(5) The electrode may be brazed to the lead rod in advance in the previous step. In addition, in the case of joining with an electrode lead rod containing a small amount of low melting point metal, instead of using the In-containing brazing material used in the present invention, the conventionally commonly used Cu-Mn-Ni brazing material is used.
There is no problem even if it is a brazing material such as. However, it is desirable to use the brazing material containing In used in the present invention.

(6) 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.

Since the brazing temperature for F1 action is approximately 700℃ or less, there is little scattering of low-melting point metals, and since the inside of the vacuum interrupter is not completely sealed during brazing, evaporated low-melting point metals will not be trapped inside the vacuum interrupter. Decrease. Moreover, the existence of a diffusion layer of Au and In in the brazed joint can suppress the intrusion of low-melting point metals into the joint interface, ensuring airtight sealing of vacuum interrupters equipped with electrodes containing low-melting point metals. It can be made highly reliable.

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

First, we will explain the results of an experiment 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 copper, which is composed of 50% by weight of Cu, 40% by weight of Cr, and 10% by weight of Bi.

(a) For a member containing a low melting point metal, approximately 160 g of Cr (chromium) powder with a particle size of 100 mesh is placed in an alumina container (inner diameter 68 mm), and Cu-
Place B1 alloy (approximately 400 g) and cover the container with a lid.
This is degassed and heat treated in a vacuum furnace at a temperature below the melting point of the Cu-B1 alloy to first diffusely bond the Cr particles to form a porous infiltrated base material.

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) For the brazing material, prepare Au and In powders with a particle size of 325 mesh,
Thoroughly mix 53 g of U and 27 g of In using a mixer.

Approximately 1.5 g was collected from the obtained mixed powder, and the diameter was 40 m.
The mixture was uniformly filled into a mold of 300 m in diameter and press-molded at 30 tons to obtain a circular thin molded product with a thickness of about 0.4 mm.

(c) Regarding brazing, the brazing material (Au-In) is placed between the Cu-CrB1 alloy member and the member made of oxygen-free copper, and these are placed in an alumina container and covered with a lid. They were bonded by heat treatment (500° C., 15 minutes) in a vacuum furnace.

(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.

Furthermore, when observing the cross section of the joint using an X-ray microanalyzer, it was confirmed that the diffusion layer of Au and In prevented Bi from precipitating at the interface, forming a stable brazed joint layer. .

(Other Experimental Examples) Under the same conditions as the above-mentioned experimental examples, brazing joints were investigated by changing the components of the brazing material. The results showed that the same results as in the above case can be obtained if the structure is in the vicinity of the eutectic points (a) and (b) shown in FIG. That is, it has been found that the brazing material may be formed of AuIn, and the In content may be 21 to 36% by weight and 38 to 53% by weight.

(Comparative Experimental Example) For comparison, commonly known 63Ag-27C
U-1,01n brazing material and Cu-Mn-Ni-based brazing material were used, and the temperature conditions were 800°C for the former and 950°C for the latter.
℃ and other conditions were the same as in the above experiment, but peeling occurred and brazing could not be performed.

(One Example) From the above results, it was found that a brazing material containing Au-In can provide sufficient bonding strength even when directly bonding a Cu (copper) 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 1 shown in FIG. 2(a) and the movable side member 2 shown in FIG. 2(b) are each formed in a pre-process.

The fixed side member l includes a fixed side end plate 13 made of Cu (copper),
It consists of a lead rod 12 made of Cu and an exhaust pipe 14 made of Cu, and a brazing material (plate-shaped brazing material, linear brazing material) is placed between these parts for temporary assembly. The bond is formed by heating to a temperature of about 1000° C. in an atmosphere (vacuum).

Moreover, the movable side member 2 includes a fixed side end plate 23 made of Cu,
It consists of a lead rod 22.5 made of Cu (stainless steel) and a bead 24 made of stainless steel.A brazing material is placed between these parts to temporarily assemble them, and then they are placed in a non-oxidizing atmosphere (vacuum). The bond is formed by heating to a temperature of approximately 1000°C.

Note that the above-mentioned brazing material used was a Cu-MnNi brazing material.

Fixed side member l and movable side member 2 formed in advance as described above
As shown in FIG. , a component containing 10% by weight of Bi) and temporarily assembled. Also, Cu is added to both ends.
The insulating tube 3 is temporarily assembled to the insulating cylinder 3 provided with auxiliary members 131 and 231 made of (copper) via brazing materials 42 and 47 (plate-shaped brazing materials), respectively. These brazing materials 42.43.44.47 are 67
Au-33In (wt%), in a non-oxidizing atmosphere (vacuum) at a temperature lower than the brazing temperature in the previous step, about 5%.
A predetermined vacuum interrupter is integrally formed by brazing and joining at 00°C, and then heated and evacuated through the exhaust pipe 14, and the desired vacuum interrupter is obtained by pinching off the exhaust pipe 14. .

The end plates 13, 23 and the auxiliary fittings 131, 231 in the vacuum interrupter thus formed were firmly joined, and an investigation using a helium leak detector confirmed that there was no leakage at all.

H1 Effects of the Invention Since the brazing material according to the present invention has Au-In as its main component, the brazing material can be heated at a temperature of 700°C or less, which effectively prevents the evaporation and scattering of low-melting point metals. This prevents low melting point metals from entering the brazing filler metal. Moreover, since a diffusion layer of Au and In is formed in the brazing material, this diffusion layer can suppress the intrusion of low melting point metals into the bonding interface.
, 1 to 20% by weight) can also provide a reliable and stable hermetic seal connection.

Further, since the brazing material has a relatively low temperature of about 700° C. or less, the thermal influence on the joining member and other structural members can be reduced.

Furthermore, after the vacuum interrupter is integrated with the brazing material, it is evacuated through an exhaust pipe to obtain the desired vacuum interrupter. The accumulation of metals such as Bi inside is reduced, and the hermetic seal joint can be made more reliable and stable.

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

[Brief explanation of the drawing]

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 diagram of a vacuum interrupter according to an embodiment of the present invention. FIG. 4 is a diagram showing the relationship between heating temperature and weight reduction rate, and FIG. 5 is a schematic diagram of a conventional vacuum interrupter. Figure 311 Mud sucking #I4 Jin Peng' External 2 people Figure 2 (-) Setsubunta Jiangheigun Jiji Figure 2 Figure 1 Law description of the present invention 1; ! ('/,) n

Claims (4)

[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, and an insulating cylinder in which the end plates of these members are hermetically joined;
A method for manufacturing a vacuum interrupter whose main component is an electrode provided at the inner end of each lead rod, comprising: a first step of forming the fixed side member and the movable side member; and the formed fixed side member and the movable side member. A second step of assembling a vacuum interrupter by brazing and joining the members and the insulating cylinder and an electrode to the inner end of each lead rod, and a second step of evacuating the inside of the assembled vacuum interrupter to obtain a vacuum interrupter. The electrode is formed of a material containing a low melting point metal, at least the end portion of the member to be brazed in the second step is formed of a copper material, and at least the airtight joint in the second step is Au-I on the part
A method for manufacturing a vacuum interrupter, characterized in that a brazing material containing n as a main component is used, and the brazing heating temperature is 700° C. or less. (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. (3) 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, and an insulating cylinder in which the end plates of these members are hermetically joined;
A method for manufacturing a vacuum interrupter whose main component is an electrode provided at the inner end of each lead rod, comprising: a first step of forming either the fixed side member or the movable side member; and the fixed side member. or a second step of brazing the other member of the movable side member to one end of the insulating tube, and brazing the other end of the insulating tube to the member obtained in the first step; The third step consists of joining and brazing an electrode to the inner end of each lead rod to form a vacuum interrupter, and the fourth step consists of evacuating the inside of the vacuum container of the assembled vacuum interrupter to obtain a vacuum interrupter. , the electrode is formed of a material containing a low melting point metal, at least the end of the member that will be the brazed part in the third step is formed of a copper material, and at least the airtight joint part in the third step is made of Au-I.
A method for manufacturing a vacuum interrupter, characterized in that a brazing material containing n as a main component is used, and the brazing heating temperature is 700° C. or less. (4) Claim 3 characterized in that at least one of the electrodes is brazed to the inner end of the lead rod in the first step and the second step.
The method for manufacturing the vacuum interrupter described in Section 1.