JP3028968B2 - Method of manufacturing contacts for vacuum valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

The present invention relates to a method for manufacturing a contact for a vacuum valve.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing the internal structure of a general vacuum valve. As shown in FIG.
A substantially cylindrical insulating container 1 made of an insulating material and metal end plates 4 and 5 mounted on both end surfaces of the insulating container via sealing fittings 2 and 3 constitute an insulating container. Is formed. A first conductive rod 7 is fixedly provided in the cut-off chamber 6 through the end plate 4 in an airtight manner, and a second conductive rod 8 is provided movably in the axial direction through the end plate 5. ing. A fixed electrode 10 having a contact 9 and a movable electrode 12 having a contact 11 are attached to opposing ends of the first conductive rod 7 and the second conductive rod 8 so as to face each other. The bellows 1 is provided between the second conductive rod 8 and the end plate 5 to maintain airtightness between the two.
3 is attached. Further, the bellows 13 is provided with an arc shield 14 for protection from arc vapor generated between the two contacts 9 and 11. The opening and closing operation as a vacuum valve is performed by a second drive mechanism (not shown).
Through the conductive rod 8.

FIG. 8 shows a conventional Cu—Cr alloy.
It is sectional drawing of an alloy contact. As shown in FIG.
The r-alloy contact is formed of a particle-like arc-resistant Cr16 and a surrounding conductive material of Cu17. Cu
The amount of other elements in the solid solution is usually kept low in consideration of conductivity.

[0004] Further, a contact in which 18 layers having a fine structure (fine structure layer) are formed on the surface of the Cu-Cr alloy contact is also used. The cross section is shown in FIG. 9 and the microstructure layer is shown in FIG. As can be seen in FIG. 10, the fine structure layer is composed of Cr particles 19 of about several μm and Cu phase between the particles.
20 .

[0005]

From the viewpoint of restriking characteristics, the above-mentioned vacuum valve contacts are required to have a smooth contact surface and high mechanical strength of the contacts.

In the case of the above-mentioned contact point shown in FIG. 8, the contact surface is in a state of being processed, so that the contact surface is very rough microscopically. Further, Cu and Cr hardly form a solid solution in a solid phase state, and even in a liquid phase state, the liquid phase is separated into two phases by a usual dissolution method. For this reason, the alloy contacts as shown in FIG. 8 are generally produced by the solid phase sintering method or the infiltration method, and the mechanical strength of the contacts is not so large, so that they are not always satisfactory for suppressing restriking. is not.

[0007] In order to improve the smoothness and mechanical strength of the contact surface, a heat treatment is performed on the contact surface to form a fine tissue layer on the contact surface. By forming such a fine layer,
The contact surface becomes fairly smooth. This fine layer is formed by melting and then solidifying a part or the whole of the contact surface. However, as described above, the Cu-Cr alloy has a two-layer separation region in the liquid phase region and a difference in melting point of Cu and Cr of 800 ° C. or more. It changes greatly depending on conditions. As shown in FIG. 10, the fine layer seen on the contact surface according to the conventional method has Cr fine particles 19 in a Cu layer 20.
Are sparsely dispersed, and the main component of the fine layer is a Cu layer. For this reason, there is a problem that the conventional contacts are not yet satisfactory in terms of mechanical strength.

An object of the present invention is to provide a Cu—C having a fine tissue layer having a very smooth surface and a very high mechanical strength.
An object of the present invention is to provide a method for manufacturing a vacuum valve contact for obtaining an r alloy contact. [Configuration of the Invention]

[0009]

In order to achieve the above object, the present invention provides a first phase composed of Cr particles having a diameter of 10 to 150 μm, a Cu phase surrounding the particles, and a 0.1 phase having a diameter of 0.1 μm.
A second phase composed of fine Cr particles of about 5 μm and a Cu phase surrounding the fine particles, and the contact surface has a small thickness.
High energy sufficient to produce a second phase of 10 μm each.
Irradiating a laser having an energy density of
微細 of the Cr particle diameter in the fine Cr particles
Production of contacts with highly dispersed Cr particles having a diameter of 00
In the manufacturing method, a maximum of 4.5 J / pal
Irradiation of laser beam with an overlap rate of 50% or more
It is characterized in that.

[0010]

The method for manufacturing a contact for a vacuum valve according to the present invention is, as described above, a laminate of a Cu plate and a Cr plate, a laminate of a Cu plate and Cr particles, a mixture of Cu particles and Cr particles, and a compact. , Cu
-High energy density over the entire contact surface of the Cr alloy body
Irradiates a sharp laser and has a very high peak temperature
Give heat history.

The above-mentioned extremely high peak temperature is a temperature far exceeding the upper limit temperature of the liquid-phase two-phase separation region determined by the contact phase formation, and a temperature at which the liquid phase can be homogenized within a very short time (that is, 2000 ° C.). Higher temperature ) , and the rapid thermal history means that the time required for cooling to pass through the liquid-phase two-phase separation temperature region is extremely short, and the extremely fine structure as described above is formed. It means that the cooling rate is high (ie, faster than 103 ° C./sec). As a result, an extremely fine structure having extremely large mechanical strength is provided on the contact surface, so that occurrence of restriking can be prevented and cutoff characteristics are improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An abrupt and extremely high peak temperature thermal history is applied to the contact surface of a Cu--Cr alloy as shown in FIG. 8 and the contact surface has an extremely fine structure as shown in FIG. 5 and FIG. Layer is formed.

The manufacturing method of the present invention is characterized in that a thermal history is given by irradiating a laser to the contact surface. Laser irradiation conditions are 4.5 J maximum energy density.
/ Pulse YAG laser, pulse width 9msec
The repetition frequency was 10 Hz. The overlap rate was set to 50% or more in order to perform laser irradiation on the entire surface.
An overlap rate of 50% means that irradiation is performed so that the length of the laser radius on the contact surface during one laser irradiation overlaps with the next irradiation. That is, by overlapping the laser irradiation, the thermal history by the laser can be given to the entire contact surface. After the laser irradiation, the re-ignition characteristics of the contacts were evaluated. The evaluation results are shown in Table 1 below.

[0015]

[Table 1] For comparison with the embodiment described above, a fine tissue layer as shown in FIGS. 9 and 10 was formed on the contact surface, and the re-ignition characteristics were evaluated.

In this case, a heat history having a lower peak temperature than that of the embodiment was given to the contact surface by arc discharge. The discharge conditions were DC 50A, gap length 5mm, arc time 10
Repeated 50 times at ms. After the discharge, the re-ignition characteristics of the contacts were similarly evaluated. This is shown in Table 1 in Comparative Example-1.
As shown. The re-ignition characteristics were also evaluated for the as-processed contacts, and the results are shown in Table 1 as Comparative Example-2.

Also, a case where a structure having the same structure as that of FIGS. 5 and 6 but having different dimensions was formed on the contact surface was evaluated, and the result is shown as Comparative Example-3. In this case, as compared with the embodiment, the contact temperature can be easily formed by giving a heat history to the contact surface having the same or higher peak temperature and a relatively slow cooling rate. Here, as an example, a Cu—Cr alloy body irradiated with laser under the conditions according to the manufacturing method of the present invention is placed in a vacuum at 95%.
The case where re-heating was performed at 0 ° C. to grow fine Cr grains was shown.

Further, although the structure and dimensions were the same as those in FIG. 6, a case where the contact was formed only on a small portion of the contact surface was evaluated and shown as Comparative Example 4. Such a state can be easily realized by performing the same heat treatment as that of the example or the comparative example by halving the number of repetitions. (Example-1)

After laminating a 30 μm thick Cr plate 31 and a 30 μm Cu plate 32 to form a Cu—Cr laminate 30 (FIG. 1), the laminate 30 is set together with a Cu substrate 33 in a laser oscillator 34. One of the surfaces of the laminated body 30, for example, the surface of the Cr plate 31, was irradiated with laser light 35 having a predetermined energy (FIG. 4) (irradiation conditions: 4 J / pulse, pulse width 9 msec, overlap ratio 50%).

By irradiation, the Cr plate 31 and the Cu plate 32 were alloyed and the interface 35 between a part of the alloy and the Cu base 33 was integrated. As a result of the investigation of the metal organization, in the region of about 30 μm deep from the surface layer, the diameter was 0.1 to 5 μm.
And a Cu phase surrounding the fine Cr (second phase), and in the region deeper than 30 μm, Cr particles having a diameter larger than 10 μm were present (first phase). Furthermore, the Cu base 33 was present as it was inside. The Cu-Cr alloy thus obtained was used as a test contact piece. Incidentally, in the fine Cr particles in the second phase,
Finer Cr particles having a diameter of 1/2 to 1/100 of the diameter of the fine Cr particles are highly dispersed. (Example-2)

After mixing Cu having an average particle diameter of 44 μm and Cr having an average particle diameter of 74 μm in a ball mill for 2 hours, 4 tons / c
m ² To obtain a molded body 57 having a diameter of 42 mm and a thickness of 3 mm (FIG. 2).

The molded body 50 was set in a laser oscillator 34, and one surface of the molded body 40 was irradiated with a laser beam 35 having a predetermined energy (condition: 3 J / pulse, pulse width 9).
msec, overlap rate 50%). By irradiation
Cu particles and Cr particles which were simply mixed were alloyed.

As a result of the investigation of the metal structure, fine Cr having a diameter of 0.1 to 5 μm exists in a region at a depth of about 40 μm from the irradiated surface, and is composed of a Cu phase surrounding the fine Cr (second phase). Phase), in a region deeper than 40 μm,
Cr particles having an average particle diameter of 74 μm used initially and a Cu phase surrounding the particles were present (first phase). The Cu-Cr alloy thus obtained was used as a test contact piece. The fine Cr particles in the second phase contain finer Cr having a diameter of 1/2 to 1/100 of the diameter of the fine Cr particles.
Particles are highly dispersed. (Example-3)

The compact 41 used in Example 2 was sintered at 1100 ° C. in vacuum, and Cu was infiltrated into the remaining void at 1150 ° C. to obtain a 50% Cr—Cu alloy body 60 (FIG. 3). ). The alloy body 60 is set in the laser oscillation device 34, and a laser beam 35 having a predetermined energy is applied to one surface of the alloy body 50.
(Conditions: 3 J / pulse, 4 ms between pulses)
c, overlap rate 50%). As a result of the investigation of the metal tissue, the region having a depth of about 50 μm
５5 μm of fine Cr exists and C surrounding the fine Cr
In a region having a depth of more than 50 μm, the first particle having a mean particle size of 74 μm is used.
r particles and a surrounding Cu phase were present (first phase). The Cu-Cr alloy thus obtained was used as a test contact piece. Further, finer Cr particles having a diameter of 1/2 to 1/100 of the diameter of the fine Cr particles are highly dispersed in the fine Cr particles in the second phase.

As can be seen from Table 1, the re-ignition probability is about 2% in the conventional contacts (Comparative Examples 1 and 2), whereas the contact manufacturing method of the present invention (Example 1). ~
In 3), the occurrence of restriking is extremely small, the restriking characteristics are remarkably improved, and the breaking characteristics are also improved. Even if the structure of the fine layer is the same, the structure is coarse. In Comparative Example 3 and Comparative Example 4 in which the formation of a fine layer was insufficient, no sufficient improvement was observed. In this example and the comparative example, the investigation was performed using a Cu-50 wt% Cr alloy contact. However, the production method according to the present invention is effective for other Cr contents.

The welding resistance of a vacuum valve using a contact formed by the manufacturing method of the present invention with a reinforced surface layer is low because the expectation that the surface layer will be released by welding and the contact will be lowered. In particular, when it is required to consider welding resistance, it is effective to add a welding resistance improving component such as Bi, for example, in an amount that does not increase restriking. In this case, destruction occurs from the matrix of FIGS. The evaluation conditions of the cutoff characteristics in the above-mentioned Examples and Comparative Examples are as follows.

A disk-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm was mounted on a demountable vacuum valve, and the breaking characteristics were evaluated by a synthetic breaking test. The circuit conditions were such that the recovery voltage was constant at 10 KV and the cutoff current was increased.

Table 1 shows the relative value of Comparative Example 2 as 100%, and shows the average value of two conditions. When mounting the contacts, baking heating (450 ° C., 30 ° C.)
Min), but no brazing material was used and no heat treatment was performed. The evaluation conditions of the restriking characteristic in the above-described examples and comparative examples are as follows.

A disk-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm was mounted on a demountable vacuum valve,
The frequency of occurrence of restriking when the circuit of × 500 A was interrupted 2,000 times was obtained (three vacuum valves). When mounting the contacts, only baking heating (450 ° C, 30 minutes) is performed.
No brazing material was used and no accompanying heating was performed.

[0030]

Since the contact of the present invention has an extremely fine structure having extremely high mechanical strength on the contact surface, the probability of occurrence of restriking is kept small and the breaking characteristics are improved. Therefore, according to the present invention, it is possible to provide a method of manufacturing a contact for a vacuum valve with further improved reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an arrangement of a Cu—Cr laminate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an arrangement of a Cu—Cr compact according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an arrangement of a Cu—Cr alloy according to an embodiment of the present invention.

FIG. 4 is a layout diagram of a laser oscillation device according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of the vacuum valve contact of the present invention.

FIG. 6 is an enlarged cross-sectional view of a surface microstructure layer of the vacuum valve contact of the present invention.

FIG. 7 is a sectional view showing the configuration of a vacuum valve.

FIG. 8 is a sectional view of a conventional Cu—Cr contact.

FIG. 9 is a cross-sectional view of a conventional vacuum valve contact having a fine layer.

FIG. 10 is an enlarged sectional view of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 30 ... Cu-Cr laminated body 33 ... Cu-Cr base 34 ... Laser oscillation device 50 ... Cu-Cr molded body 60 ... Cu-Cr alloy body

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Tamagawa 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Corporation Hamakawasaki Plant (72) Inventor Mitaka Honma 1-Toshiba-cho, Fuchu-shi, Tokyo East Shiba Fuchu Plant (72) Inventor Seichiro Kimura 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Plant Co., Ltd. (56) References JP-A-2-226623 (JP, A) JP-A-59-143031 ( JP, A) JP-A-54-56178 (JP, A) JP-A-63-141226 (JP, A) JP-A-1-258330 (JP, A) JP-A-3-254020 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01H 33/66 H01H 11/04

Claims (1)

(57) [Claims] 1. A first phase composed of Cr particles having a diameter of 10 to 150 μm, a Cu phase surrounding the particles, and a first phase having a diameter of 0.1 μm.
It consists of a second phase composed of fine Cr particles of 1 to 5 μm and a Cu phase surrounding it, and the contact surface has a small thickness.
A high energy sufficient to produce a second phase of at least 10 μm.
The second phase is irradiated by irradiating a laser having an energy density.
In the fine Cr particles in the middle, approximately 1/2 to 1/1 /
Of highly dispersed contacts with Cr particles having a diameter of 100
In the manufacturing method, a maximum of 4.5 J / p
Lus laser light with an overlap ratio of 50% or more.
Method of manufacturing a contact for a vacuum valve, characterized in that the morphism.