Vacuum valve manufacturing method

Abstract

To provide a manufacturing method of a vacuum valve, capable of reducing a manufacturing cost, and improving a same core level.SOLUTION: In a manufacturing method of a vacuum valve, a brazing material (4) is heated in vacuum and is welded after the brazing material is arranged and temporally assembled to between one end of an insulation cylinder (3a) and a fixing side metal end board (2b), and between the other end of the insulation cylinder (3a) and a movable side metal end board (1b), and an air tight sealing between the one end of the insulation cylinder (3a) and the fixing side metal end board (2b), and the other end of the insulation cylinder (3a) and the movable side metal end board (1b) is made. A divided brazing material piece (4a) obtained by dividing the plurality of brazing materials (4) is temporally assembled, a claw part (4b) formed in the divided brazing material piece (4a) is contacted to a cylinder surface of the insulation cylinder (3a) to position each brazing material (4), and the air tight sealing is made.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present application relates to a method for manufacturing a vacuum valve. [Background technology]

[0002] Vacuum interrupters are used in the arc extinguishing chambers of vacuum circuit breakers and vacuum switchgears. They consist of a moving assembly, a fixed assembly, and an insulating cylinder. The moving assembly and fixed assembly each consist of a metal end plate, an electrode rod, and contacts. Both ends of the insulating cylinder are metallized.

[0003] During temporary assembly, brazing material is placed between each metal end plate and the metallized surface of the insulating cylinder. The temporary assembly is heated in a vacuum furnace, which evacuates the gas inside the insulating cylinder before the brazing material melts. After evacuation, the brazing material melts and solidifies, sealing the metal end face and the end face of the insulating cylinder in an airtight seal, completing the vacuum valve. A bellows is attached to the moving assembly, allowing opening and closing operations to be performed while maintaining the vacuum inside the insulating cylinder.

[0004] Patent Document 1 discloses a brazing filler metal with multiple protrusions that abut against the outer or inner surfaces of the insulating cylinder and metal end plate to position them during pre-assembly. The formed protrusions enable the insulating cylinder and metal end plate to be positioned while maintaining concentricity in the pre-assembly state without using a special jig, reducing manufacturing costs and improving quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2-195618 [Patent Document 2] Japanese Patent Application Publication No. 10-321094 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional vacuum valve manufacturing method described above, the brazing filler metal is mainly made of silver or other materials, which are very expensive. The brazing filler metal disclosed in Patent Document 1 is pressed into a ring shape, resulting in a large amount of scrap material. This has resulted in the problem of high manufacturing costs.

[0007] Furthermore, if the dimensions of the insulating tube are large and the tolerance of the insulating tube is large, the insulating tube and the protruding portion of the brazing material do not come into contact with each other, which causes a problem of misalignment in concentricity.

[0008] The present application discloses a technique for solving the above-mentioned problems, and its object is to provide a method for manufacturing a vacuum interrupter that reduces manufacturing costs and has good concentricity. [Means for solving the problem]

[0009] The method for manufacturing a vacuum valve disclosed in the present application is a method for manufacturing a vacuum valve in which brazing filler metal is placed between one end of the insulating cylinder and the fixed side metal end plate, and between the other end of the insulating cylinder and the movable side metal end plate, and then the brazing filler metal is vacuum heated and welded to hermetically seal one end of the insulating cylinder to the fixed side metal end plate, and the other end of the insulating cylinder to the movable side metal end plate, respectively.The brazing filler metal is divided into multiple pieces, which are temporarily assembled into a ring shape, and the claw portions formed on the divided brazing filler metal pieces are abutted against the cylindrical surface of the insulating cylinder to position the brazing filler metal and hermetically seal it. [Effects of the Invention]

[0010] According to the method for manufacturing a vacuum valve disclosed in the present application, it is possible to obtain a method for manufacturing a vacuum valve that reduces manufacturing costs and improves concentricity. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a vacuum interrupter to which the vacuum interrupter manufacturing method according to the first embodiment is applied. [Figure 2] 1 is a perspective view showing a brazing material in a manufacturing method for a vacuum interrupter according to Embodiment 1. FIG. [Figure 3] 3 is an explanatory view showing the arrangement of slits in the brazing filler metal of FIG. 2 in the method for manufacturing the vacuum interrupter according to the first embodiment. FIG. [Figure 4] 3 is a cross-sectional view showing a fitting portion between a brazing filler metal and a metal end plate in the method for manufacturing a vacuum interrupter according to the first embodiment. FIG. [Figure 5] 3 is a cross-sectional view showing a main part of a fitting portion between a brazing material and an insulating cylinder in a manufacturing method for a vacuum interrupter according to the first embodiment. FIG. [Figure 6] 1 is a perspective view showing a state in which brazing filler metals are combined in a method for manufacturing a vacuum interrupter according to the first embodiment. [Figure 7] 7 is a plan view showing a fitting portion of the brazing material of FIG. 6 in the method of manufacturing the vacuum interrupter according to the first embodiment. FIG. [Figure 8] FIG. 10 is a perspective view showing a brazing material in a manufacturing method of a vacuum interrupter according to a second embodiment. [Figure 9] FIG. 10 is a perspective view showing a state in which brazing filler metals are combined in a manufacturing method for a vacuum interrupter according to a second embodiment. [Figure 10] 10 is a plan view showing the fitting portion of the brazing material of FIG. 9 in the method of manufacturing the vacuum interrupter according to the second embodiment. FIG. [Figure 11] FIG. 10 is a perspective view showing a brazing material used in a conventional method for manufacturing a vacuum interrupter. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiment 1 A first embodiment of the present invention will be described below with reference to FIGS. 1 to 7, with the same or corresponding components and parts being designated by the same reference numerals in each drawing. FIG. 1 is a cross-sectional view of a vacuum interrupter to which a manufacturing method for a vacuum interrupter according to the first embodiment is applied. FIG. 2 is a perspective view showing a brazing filler metal in the manufacturing method for a vacuum interrupter according to the first embodiment. FIG. 3 is an explanatory diagram showing the slit arrangement of the brazing filler metal of FIG. 2 in the manufacturing method for a vacuum interrupter according to the first embodiment. FIG. 4 is a cross-sectional view showing a fitting portion between the brazing filler metal and a metal end plate in the manufacturing method for a vacuum interrupter according to the first embodiment. FIG. 5 is a cross-sectional view showing a main part of the fitting portion between the brazing filler metal and an insulating sleeve in the manufacturing method for a vacuum interrupter according to the first embodiment. FIG. 6 is a perspective view showing the assembled state of the brazing filler metal in the manufacturing method for a vacuum interrupter according to the first embodiment. FIG. 7 is a plan view showing the fitting portion of the brazing filler metal of FIG. 6 in the manufacturing method for a vacuum interrupter according to the first embodiment.

[0013] As shown in Figure 1, the vacuum interrupter is broadly composed of a moving-side assembly 1, a fixed-side assembly 2, and an insulating cylinder assembly 3. In the moving-side assembly 1, a moving-side electrode rod 1a having a moving-side contact 1e is joined to a moving-side metal end plate 1b via a bellows 1c and a bellows cover 1d. The bellows 1c is flexible and can expand and contract in the axial direction, and plays a role in expanding and contracting in accordance with the movement of the moving-side electrode rod 1a during contact opening and closing operations.

[0014] Meanwhile, the fixed-side assembly 2 has a fixed-side metal end plate 2b joined to a fixed-side electrode rod 2a having a fixed-side contact 2c. The insulating cylinder assembly 3 is composed of an insulating cylinder 3a and a shield 3b, and both end surfaces of the insulating cylinder 3a are metallized. A brazing filler metal 4, which is made by temporarily assembling multiple divided brazing filler metal pieces 4a into an annular shape, is placed between the fixed-side metal end plate 2b and one end of the insulating cylinder 3a, and between the movable-side metal end plate 1b and the other end of the insulating cylinder 3a, and the brazing filler metal 4 is vacuum-heated and welded to form an airtight seal. The shield 3b prevents metal vapor generated by the arc between the two electrodes from adhering to the inner surface of the insulating cylinder 3a, thereby preventing a decrease in the dielectric strength between the electrodes.

[0015] 2 and subsequent figures will be described mainly with reference to the temporary assembly of the fixed metal end plate 2b, one end of the insulating tube 3a, and the brazing filler material 4. As shown in Fig. 2, the width of the divided brazing filler material pieces 4a of the divided brazing filler material 4 is approximately the same as the thickness of the insulating tube 3a. A normal brazing filler material has the shape of an annular brazing filler material 5 as shown in Fig. 11, but in order to reduce scrap in the press working, in this embodiment 1 the annular brazing filler material is divided into a plurality of pieces, for example, four divided fan-shaped divided brazing filler material pieces 4a.

[0016] The central angle α of the fan-shaped divided brazing material pieces 4a is 360° ÷ the number of divisions + β°. β can be varied by changing the number and spacing of the multiple slits that make up the second engagement portions 4d. The central angle in Figure 2 is α = 100° because it shows a case where the brazing material is divided into four and β = 10°. The divided brazing material pieces 4a of the brazing material 4 have claw portions 4b that are perpendicular to the circumferential direction and abut against the cylindrical surface, for example the inner peripheral surface, of the insulating tube 3a.

[0017] Although not shown in detail, the movable side metal end plate 1b, the other end of the insulating tube 3a, and the brazing material 4 have the same structure as the fixed side metal end plate 5, one end of the insulating tube 3a, and the brazing material 4.

[0018] A first engagement portion 4c consisting of a protrusion perpendicular to the circumferential direction is provided on one side of the divided brazing material piece 4a of the brazing material 4, and a second engagement portion 4d consisting of a plurality of slits is provided on the other side of the divided brazing material piece 4a, and the protrusion, which is the first engagement portion 4c, is fitted into the slit, which is the second engagement portion 4d, to form a ring-shaped brazing material 4.

[0019] The center points of the slits, which are the second engagement portions 4d of the divided brazing filler metal pieces 4a, are positioned as follows: They are on the circumference of a circle whose center is the center point of the protruding piece, which is the first engagement portion 4c in Fig. 3, and whose radius is the straight line connecting the center point of the protruding piece, which is the first engagement portion 4c, and the center point of the slit, which is the second engagement portion 4d.

[0020] Hereinafter, unless otherwise specified, "annular brazing filler metal 5" refers to a brazing filler metal having a general annular shape, and "brazing filler metal 4" refers to a brazing filler metal in which fan-shaped divided brazing filler metal pieces 4a are arranged in a ring shape, as shown in this disclosure. Although the division method is described as being divided into four, it is sufficient to divide it into at least two or more, and it is not limited to equal divisions, as long as it forms a ring when combined.

[0021] The temporarily assembled brazing filler metal 4 is placed at both ends of the insulating tube 3a, and then the movable-side metal end plate 1b and the fixed-side metal end plate 2b are placed on top of the brazing filler metal 4. When the brazing filler metal 4 is placed, the claw portions 4b of the divided brazing filler metal pieces 4a are brought into contact with the circumferential surface, for example the inner circumferential surface, of the insulating tube 3a to position the brazing filler metal 4, and the protruding pieces that are the first engaging portions 4c of the divided brazing filler metal pieces 4a are brought into contact with the circumferential surface, for example the inner circumferential surface, of the movable-side metal end plate 1b, and the circumferential surface, for example the inner circumferential surface, of the fixed-side metal end plate 2b to obtain a restraining force.

[0022] Generally, the movable-side metal end plate 1b and the fixed-side metal end plate 2b are press-formed products, and the dimensional tolerance of the inner surfaces is within ±0.5 mm as required by JIS B 0408-A. Therefore, a stable restraining force can be obtained using only the protruding pieces that form the first engaging portions 4c of the divided brazing filler metal pieces 4a. As shown in Figure 4, the protruding pieces that form the first engaging portions 4c of the divided brazing filler metal pieces 4a face upward so that they abut against the inner surfaces of the movable-side metal end plate 1b and the fixed-side metal end plate 2b.

[0023] 5, the claw portions 4b of the divided brazing filler metal pieces 4a face downward so as to abut against the circumferential surface, for example, the inner circumferential surface, of the insulating tube 3a. As described above, the claw portions 4b of the divided brazing filler metal pieces 4a and the protruding pieces serving as the first engaging portions 4c of the divided brazing filler metal pieces 4a are rectangular in shape and abut against the inner circumferential surfaces of the movable-side metal end plate 1b, the fixed-side metal end plate 2b, and the insulating tube 3a, respectively, as shown in FIGS. 4 and 5. However, this is not limited thereto, and the claw portions 4b of the divided brazing filler metal pieces 4a and the protruding pieces serving as the first engaging portions 4c of the divided brazing filler metal pieces 4a may also abut against the outer circumferential surfaces of the movable-side metal end plate 1b, the fixed-side metal end plate 2b, and the insulating tube 3a, respectively. Furthermore, the shapes of the claw portions 4b of the divided brazing filler metal pieces 4a and the protruding pieces serving as the first engaging portions 4c of the divided brazing filler metal pieces 4a may be circular, triangular, or elliptical, for example, and the same effect will be achieved.

[0024] Figure 6 is an enlarged perspective view of the brazing filler metal 4, which is a temporary annular assembly of the fan-shaped brazing filler metal pieces 4a shown in Figures 2 and 3. Figure 11 shows that the resulting shape is similar to that of a conventional annular brazing filler metal 5. The inner diameter tolerance of the insulating tube 3a varies greatly due to individual differences. The inner diameter dimensional tolerance of the insulating tube 3a is generally ±0.5 mm or more, and the tolerance increases as the diameter increases. For this reason, when temporary assembly is performed using the annular brazing filler metal 5 shown in Figure 11, as shown in Figures 2 and 4, the claw portions 4b of the divided brazing filler metal pieces 4a, which should be in contact with the inner surface of the insulating tube 3a, do not all abut the inner surface of the insulating tube 3a. This creates a gap between the inner surface of the insulating tube 3a and the claw portions 4b of the divided brazing filler metal pieces 4a. Since the annular brazing filler metal 5 and the insulating tube 3a are not coaxial, a misalignment occurs. However, in the case of the fan-shaped brazing filler metal 4 of the present application, when the brazing filler metal 4 is temporarily assembled, it is possible to adjust the fitting position between the protrusion piece, which is the first engagement portion 4c of the split brazing filler metal piece 4a, and the multiple slits, which are the second engagement portion 4d of the split brazing filler metal piece 4a, so that the claw portions 4b of all the split brazing filler metal pieces 4a abut against the inner surface of the insulating tube 3a, thereby minimizing the gap between the inner surface of the insulating tube 3a and the claw portions 4b of the split brazing filler metal pieces 4a.

[0025] Fig. 7 is an enlarged plan view showing the fitting portion between the protruding piece, which is the first engagement portion 4c of the split brazing filler metal piece 4a shown in Fig. 6, and the slit 4d, which is the second engagement portion 4d of the split brazing filler metal piece 4a and is located at the end-most side of the multiple slits. When the dimensional tolerance of the inner diameter of the insulating tube 3a is large, fitting the protruding piece, which is the first engagement portion 4c of the split brazing filler metal piece 4a, into the slit 4d, which is located at the end-most side of the second engagement portion 4d of the split brazing filler metal piece 4a, as shown in Fig. 7, allows the claw portion 4b of the split brazing filler metal piece 4a to abut against the inner circumferential surface of the insulating tube 3a, while the protruding piece, which is the first engagement portion 4c of the split brazing filler metal piece 4a, to abut against the inner circumferential surfaces of the movable-side metal end plate 1b and the fixed-side metal end plate 2b at all times.

[0026] Furthermore, if the dimensional tolerance of the inner diameter of the insulating tube 3a is small, by fitting the protruding piece that is the first engaging portion 4c of the split brazing filler metal piece 4a into the innermost slit 4d that is the second engaging portion 4d of the split brazing filler metal piece 4a, the claw portion 4b of the split brazing filler metal piece 4a can abut the inner peripheral surface of the insulating tube 3a, while the protruding piece that is the first engaging portion 4c of the split brazing filler metal piece 4a can also abut the inner peripheral surfaces of the movable-side metal end plate 1b and the fixed-side metal end plate 2b at all times. Note that the number of slits that are the second engaging portions 4d of the split brazing filler metal piece 4a is not limited to the number disclosed in the present disclosure and can be adjusted according to the dimensional tolerance of the inner diameter of the insulating tube 3a.

[0027] As described above, the claw portion 4b of the split brazing material piece 4a abuts against the inner surface of the insulating tube 3a, and the protrusion piece which is the first engagement portion 4c of the split brazing material piece 4a abuts against the inner surfaces of the movable side metal end plate 1b and the fixed side metal end plate 2b, making it possible to position the movable side metal end plate 1b, the fixed side metal end plate 2b and the insulating tube 3a concentrically without using a special positioning jig, thereby improving the concentricity accuracy of the vacuum valve.

[0028] In addition, in order to reduce scrap during press processing, the shape of the brazing filler metal is changed from a ring to multiple fan-shaped divided brazing filler metal pieces, and the divided brazing filler metal pieces are temporarily assembled into the ring-shaped brazing filler metal, which makes it possible to manufacture using the minimum amount of material necessary and significantly reduce manufacturing costs.

[0029] Embodiment 2 A second embodiment of the present invention will be described with reference to Figures 8 to 10, with the same or corresponding components and parts being designated by the same reference numerals in each figure. Figure 8 is a perspective view showing a brazing material in a manufacturing method for a vacuum interrupter according to the second embodiment. Figure 9 is a perspective view showing an assembled state of the brazing material in a manufacturing method for a vacuum interrupter according to the second embodiment. Figure 10 is a plan view showing the fitting portion of the brazing material in Figure 9 in a manufacturing method for a vacuum interrupter according to the second embodiment.

[0030] In this second embodiment, similarly to the first embodiment, the brazing filler metal 4 is temporarily assembled into a ring shape by dividing, for example, four divided brazing filler metal pieces 4a, and the width of the divided brazing filler metal pieces 4a of the divided brazing filler metal 4 is approximately the same as the thickness of the insulating tube 3a. The divided brazing filler metal pieces 4a of the brazing filler metal 4 have claw portions 4b that are perpendicular to the circumferential direction and come into contact with the cylindrical surface, for example the inner peripheral surface, of the insulating tube 3a.

[0031] A convex engaging portion 4e is provided on one side of the divided brazing filler metal piece 4a of the brazing filler metal 4, and a concave engaging portion 4f is provided on the other side of the divided brazing filler metal piece 4a, and the convex engaging portion 4e is fitted into the concave engaging portion 4f to temporarily assemble the annular brazing filler metal 4. The method of arranging the convex engaging portion 4e and the concave engaging portion 4f is the same as that described in the first embodiment above, with the center point as the reference point.

[0032] The divided brazing filler metal pieces 4a are provided with, for example, rectangular bent pieces 4g, 4h that are perpendicular to the circumferential direction, and the bent piece 4g is arranged to abut against the inner peripheral surfaces of the movable-side metal end plate 1b and the fixed-side metal end plate 2b, while the bent piece 4h is arranged to abut against the outer peripheral surfaces of the movable-side metal end plate 1b and the fixed-side metal end plate 2b. Furthermore, the shapes of the claw portions 4b of the divided brazing filler metal pieces 4a, the bent pieces 4g of the divided brazing filler metal pieces 4a, and the bent pieces 4h of the divided brazing filler metal pieces 4a may be, for example, circular, triangular, or elliptical, and the same effect will be achieved.

[0033] Fig. 9 is a perspective view showing the brazing filler metal 4 obtained by temporarily assembling the fan-shaped divided brazing filler metal pieces 4a shown in Fig. 8 into an annular shape. As shown in Fig. 11, this results in a shape similar to that of a conventional annular brazing filler metal piece 5. Fig. 10 is an enlarged plan view showing the fitting portion between the convex engaging portion 4e of the divided brazing filler metal piece 4a shown in Fig. 9 and the concave engaging portion 4f of the divided brazing filler metal piece 4a.

[0034] One difference from the first embodiment described above is that in the second embodiment, when the fan-shaped divided brazing filler metal pieces 4a are temporarily assembled into an annular shape, no steps are created, resulting in a shape similar to that of the conventional annular brazing filler metal 5. The advantage of having steps is that they provide the exhaust groove function of the exhaust conductance, but the disadvantage is that they result in a loss of flatness, which risks compromising the flatness of the finished product. If the exhaust conductance is insufficient, as described in the background art above, the brazing filler metal will melt and solidify before the gas inside the insulating tube is sufficiently exhausted, resulting in a vacuum interrupter with poor vacuum integrity. In the second embodiment, when temporarily assembled into an annular shape, no steps are created, and gaps are created in the mating parts, so flatness is not lost while maintaining the exhaust groove function.

[0035] The convex engagement portion 4e of the split brazing material piece 4a is configured to be circular, and the concave engagement portion 4f of the split brazing material piece 4a is configured to be a rectangular elliptical slit, and it is possible to adjust the engagement position between the circular convex engagement portion 4e and the concave engagement portion 4f consisting of a rectangular elliptical slit, thereby minimizing the gap between the inner surface of the insulating tube 3a and the claw portion 4b of the split brazing material piece 4a.

[0036] The shapes of the convex engagement portion 4e of the split brazing material piece 4a and the concave engagement portion 4f of the split brazing material piece 4a are not limited to the shape shown in Figure 10, and may be any shape that allows adjustment of the engagement position between the convex engagement portion 4e of the split brazing material piece 4a and the concave engagement portion 4f of the split brazing material piece 4a.

[0037] As described above, the claw portion 4b of the split brazing material piece 4a abuts against the inner surface of the insulating tube 3a, the bent portion 4g of the split brazing material piece 4a abuts against the inner surfaces of the movable side metal end plate 1b and the fixed side metal end plate 2b, and the bent portion 4h of the split brazing material piece 4a abuts against the outer surfaces of the movable side metal end plate 1b and the fixed side metal end plate 2b.This makes it possible to position the movable side metal end plate 1b, the fixed side metal end plate 2b and the insulating tube 3a concentrically without using a special positioning jig, thereby improving the concentricity accuracy of the vacuum valve.

[0038] In addition, in order to reduce scrap during press processing, the shape of the brazing filler metal is changed from a ring to multiple divided fan-shaped brazing filler metal pieces, and the divided brazing filler metal pieces are temporarily assembled into a ring to form the brazing filler metal, which can be produced using the minimum amount of material necessary, resulting in a significant reduction in manufacturing costs.

[0039] In each of the above-mentioned embodiments, the claw portions 4b of the split brazing material pieces 4a are described as being in contact with the inner surface of the insulating tube 3a, but this is not limited to this, and it is also possible to configure the claw portions 4b of the split brazing material pieces 4a to be in contact with the outer surface of the insulating tube 3a, which will achieve the same effect.

[0040] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in the present specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Industrial Applicability]

[0041] The present invention is suitable for realizing a method for manufacturing a vacuum valve that can reduce manufacturing costs and improve concentricity. [Explanation of symbols]

[0042] 1. Movable side assembly, 1a. Movable side electrode rod, 1b. Movable side metal end plate, 1c. Velcro, 2. Fixed side assembly, 2a. Fixed side electrode rod, 2b. Fixed side metal end plate, 3. Insulation tube assembly, 3a. Insulation tube, 4. Segmented material, 4a. Segmented material sheet, 4b. Claw, 4c. First connecting part, 4d. Second connecting part, 4e. Convex connecting part, 4f. Concave connecting part, 4g, 4h. Folded piece

Claims

1. A method for manufacturing a vacuum valve, comprising the steps of: disposing and temporarily assembling brazing filler metal between one end of an insulating cylinder and a fixed-side metal end plate, and between the other end of the insulating cylinder and a movable-side metal end plate; and then vacuum-heating and fusing the brazing filler metal to hermetically seal the one end of the insulating cylinder to the fixed-side metal end plate, and the other end of the insulating cylinder to the movable-side metal end plate, A method for manufacturing a vacuum valve, characterized in that the brazing material is divided into multiple pieces, which are temporarily assembled into a ring shape, and the claw portions formed on the divided brazing material pieces are abutted against the cylindrical surface of the insulating tube to position the brazing material and seal it airtight.

2. A method for manufacturing a vacuum valve as described in claim 1, characterized in that a first engaging portion is provided on one side of the divided brazing material piece, a second engaging portion is provided on the other side of the divided brazing material piece, and the first engaging portion is engaged with the second engaging portion to temporarily assemble into a ring shape.

3. A method for manufacturing a vacuum valve as described in claim 2, characterized in that the first engagement portion of the divided brazing material piece is formed as a protrusion piece, the second engagement portion of the divided brazing material piece is formed as a slit, and the protrusion piece is engaged with the slit to temporarily assemble into a ring shape.

4. A method for manufacturing a vacuum valve as described in claim 3, characterized in that the protruding pieces of the divided brazing material pieces abut against the peripheral surfaces of the fixed side metal end plate and the movable side metal end plate to hold the fixed side metal end plate and the movable side metal end plate.

5. 3. A method for manufacturing a vacuum valve as described in claim 2, characterized in that the first engaging portion of the divided brazing material piece is configured as a convex engaging portion, the second engaging portion of the divided brazing material piece is configured as a concave engaging portion, and the convex engaging portion is engaged with the concave engaging portion to temporarily assemble into a ring shape.

6. A method for manufacturing a vacuum valve as described in claim 5, characterized in that a bent piece formed on the divided brazing material piece is abutted against the peripheral surfaces of the fixed side metal end plate and the movable side metal end plate to hold the fixed side metal end plate and the movable side metal end plate.

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