JPS61190817A - Electric contact - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrical contact with excellent welding resistance, and more particularly to an electrical contact used in a power relay, for example.

[Background technology]

Electric contacts are known that have a plurality of regions on a contact surface having different contact characteristics, such as a region with good arc resistance characteristics and a region with good current conduction characteristics (low contact resistance when energized). The principle of the connecting and disconnecting operation of the composite electrical contact of the present invention will be explained with reference to FIG. The fixed side contact 1 is provided with a contact in which a region 1a with good arc resistance characteristics is formed on the back half of the region 1b with good current conduction characteristics, and on the other hand, the movable side contact 2 is also provided with a region 1a with good current conduction characteristics. A contact is provided in which a region 2a having good arc resistance characteristics is formed on the back half of the good region 2b. When the contact is closed, as shown in Figure 4(a),
First, regions 1a and 2a with good arc resistance properties are bonded, and then, as shown in Figure 4 (bl), regions 1a and 2a with good current carrying properties are bonded.
b and 2b are bonded to each other and enter a steady energized state. Conversely, when the contacts are opened, regions 1a, 2a are the last to separate.

Due to this mechanism, arc generation naturally concentrates mainly at the time of first contact and last time of separation, but since regions 1a and 2a have good arc resistance, welding of the contacts is prevented. - Can avoid wear and tear. On the other hand, since the contact resistance of regions 1a and 2a is low, temperature rise is prevented during normal energization.

The following is known as a conventional example of this composite contact. In other words, materials with good arc resistance (e.g. tungsten) and materials with low contact resistance (e.g. silver)
By using the so-called gravitational sedimentation method that utilizes the difference in specific gravity (tungsten: 19°3, silver: 10.49), the composition ratio of tungsten is significantly higher at one end of the contact, and the composition ratio of tungsten gradually decreases as you move away from this end. This is an electrical contact obtained by making a mixture, compression molding this mixture, and then sintering it. However, these conventional electrical contacts have difficulties in process control to continuously change the distribution of the composition ratio as desired, variations in the continuous distribution state for each manufacturing loft, and welding resistance due to local uneven distribution of silver. There were problems in terms of manufacturing process and performance, such as a decrease in performance.

In order to solve this problem, three types of composition pieces 1)a and 1)b with different composition ratios are prepared in which different amounts of carbon are uniformly dispersed in the eyes.

1) Make c separately and sort them in order of carbon content (composition piece 1) as shown in Figure 5.
A composite electrical contact has been proposed in which the two components are lined up and integrally bonded using an ultrasonic bonding method, and then this integrally bonded product is brazed to the pedestal 12. However, in this conventional example, in order to perform ultrasonic bonding of three very small composition pieces 1) a, llb, and llc with different composition ratios, an integrally bonded piece with sufficient bonding dimensional accuracy and bonding strength is required. It is difficult to obtain, and its dimensions and strength are not necessarily sufficient. Furthermore, since integrally bonded products with stepwise different composition ratios are further brazed to the pedestal 12, the adhesive strength varies depending on the composition piece and the pedestal 12 and Adhesion with integrally bonded objects also becomes unstable. Therefore, there was a problem in that the reliability and durability when operated as an electrical contact were insufficient.

[Purpose of the invention]

In order to solve the above-mentioned problems, this invention provides a composite electrical contact that has extremely strong bonding strength between different areas, is homogeneous without uneven distribution of materials, and is highly durable and reliable. With the goal.

[Disclosure of the invention]

To achieve the above object, the present invention provides an electrical contact comprising a plurality of regions having different contact characteristics, wherein at least one of the regions is formed by thermal spraying a contact material. The gist is: Hereinafter, the present invention will be explained based on FIG. 1, which shows the manufacturing process of an embodiment of the electrical contact of the present invention in order, and FIG. 2, which mainly shows the schematic structure of the electrical contact of this embodiment. Explain.

The base material 31 shown in FIG. 1(a) is made of a material such as silver, which has poor arc resistance but very good current-carrying properties.
Cut grooves 32 as shown in . To cut the grooves 32, any suitable known method such as milling or laser machining can be used. Alternatively, a mold may be prepared in advance and the base material 31 with the grooves 32 may be made from the beginning. Next, a high melting point metal material with good arc resistance is thermally sprayed into the groove 32. The specific thermal spraying operation will be explained in detail later. At this time, in order to cover the surfaces 31a and 31b adjacent to the groove 32, a metal slit, which is open at the groove 32, is placed on the surface of the base material 31. In this way, surfaces 31a, 31b
Prevent high melting point metal materials from adhering to the As a result of this thermal spraying, as shown in FIG. 1(C), a region 33 with good arc resistance characteristics is bonded within the region 31 with good current conduction characteristics.

Then, it is cut along the cutting line 35 shown in FIG. 1 (dl) to the required size, and finally, the contacts are arranged in the desired shape as shown in FIG. 1 (e). As a result, a contact area 3 with good arc resistance characteristics is formed by thermal spraying on the step-shaped notch provided in the area 31 with good current conduction characteristics.
3 was formed as a bond. Next, as shown in FIG. 2, the base material 31 is brazed onto the pedestal 34 to complete the contact.

In this way, in this invention, the area with good arc resistance characteristics is bonded to the area with good current carrying characteristics by melting the contact material at high temperature by thermal spraying and spraying it onto the base material. Therefore, it is bonded to the base material, that is, other areas, with a very strong adhesive force, and has a homogeneous composition without uneven distribution of the base material on the surface.

In the embodiment, since the surface that is brazed to the pedestal 34 is only the lower surface of the base material 31, there is no positional irregularity in the adhesive force and it is strongly bonded to the pedestal 34.

According to the above manufacturing method, at the position defined by the metal slit,
Since separate areas are formed by thermal spraying, the composite contact can be finished with extremely high dimensional accuracy. Compared to the conventional gravity sedimentation method and the ultrasonic bonding method of divided composition pieces described above, the number of steps is smaller, so the manufacturing period can be shortened. Next, based on FIG. 3, a method of spray bonding the high melting point arc-resistant contact metal material to the substrate 31 by plasma spraying will be specifically explained.

When a high voltage of the illustrated polarity is applied by a power source 43 between a tungsten cathode 41 and a copper anode 42, an arc is generated. A working gas (single gas or mixed gas of Ar, N2, and H2) is introduced into this arc part from the gas inlet 44 to cause ionization, and the surrounding area of the conductive gas ionized by this arc is cooled, and the current When concentrated, an extremely high temperature condition is generated, the gas expands, and an extremely high temperature plasma jet 46 is generated. This plasma jet 4
6 is ejected from the opening 45, and high melting point metal (tungsten) powder is supplied from the supply pipe 47 with an inert gas into the high temperature region 46a of the plasma jet 46 formed near the opening 45. . The tungsten particles melted in this high temperature region 46a are transferred to the metal slit 48 of the base material 31.
A region 33 with good arc resistance is bonded within the groove 32 which is not blocked by the arc. If excess bonding material adheres to the area 33 and bulges, scrape it to make it flat.
The surfaces 31a and 31b of the base material 31 are made to be on the same plane. In the above description of thermal spraying, the plasma spraying method was used as an example, but it goes without saying that the present invention is not limited to this, and other thermal spraying methods may be used. For example, H2 gas.

The spray powder is placed in a supersonic combustion flame formed by either propylene gas or propane gas and N2 gas.
There are supersonic thermal spraying methods that use an inert gas such as gas, low-kite process thermal spraying that sprays by placing a rod-shaped spray material at the base of a high-temperature plasma jet, and the well-known explosive thermal spraying method. These are thermal spray materials,
It is used appropriately depending on the type of base material to be thermally sprayed. In the explanation so far, W (tungsten) has been exemplified as a high melting point metal material with good arc resistance, but other materials such as molybdenum may also be used, and the material is not limited to tungsten. Next, a more specific example will be explained. Base material 3
As Example 1, a silver plate having a thickness of 1 dragon, 9 width, 8 cranes, and a length of 50 m was used, and a groove 32 with a depth of 0.2 m and a width of 41 was cut into this silver plate using a milling machine. A copper plate was used as the slit plate 48, and tungsten powder was plasma sprayed thereon.

The gas for forming the plasma jet in this thermal spraying was H2 gas, and the thermal spray particles were accelerated to 600 m/sec with an input power of 50 KW. After thermal spraying, the first figure (4 in width and 4 fi in length)
It was cut and shaped into the shape shown in el and brazed to the copper pedestal 34 with solder.

The electrical contacts made in this way were incorporated into a power relay, and a rush current IKA welding resistance test and a 200V, 15A AC1 test as specified in JIS 8325 (7, 9) were conducted to examine changes in contact resistance. Ta. As shown in Figure 1, the power relay under test has a built-in mechanism in which the arc during opening and closing is interrupted in the contact region with good arc resistance characteristics, and energization during steady state is carried out in the region with good current conduction characteristics. It is. As a result of the test, it was confirmed that the welding resistance was very high, there was almost no increase in the contact resistance value, and the initial low contact resistance was maintained.

In the contact area, there was no falling off of the sprayed joints due to opening/closing operations, and no peeling of the brazed surfaces of the base.

〔Effect of the invention〕

As described in detail above, in this invention, at least one of the plurality of regions having different contact characteristics is bonded by thermal spraying of contact material, so the bonded regions are strongly adhered to each other, and moreover, local It has a uniform composition with no uneven distribution of materials. Therefore, according to the present invention, an electrical contact with high durability and reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining step by step the manufacturing process of an embodiment of the present invention, FIG. 2 is a perspective view showing a schematic structure of an electrical contact of an embodiment of the invention, and FIG. is a schematic explanatory diagram when plasma spraying a high-melting-point arc-resistant contact material onto a base material, FIG. 4 is an explanatory diagram for explaining the principle of attachment/detachment operation of an electric contact according to the present invention, and FIG. FIG. 1 is a perspective view of a conventional composite electrical contact. 31... Base material 32... Groove 33... Area with good arc resistance properties 34... Pedestal 41... Cathode
42... Anode 43... Power supply 44... Gas inlet 46... Plasma jet agent Patent attorney Takehiko Matsumoto Figure 1 Figure 4 Figure 5

Claims (7)

[Claims] (1) An electrical contact comprising a plurality of regions having different contact characteristics, wherein at least one of the regions is formed by thermal spraying a contact material. (2) The electrical contact according to claim 1, wherein the plurality of regions having different contact characteristics are a region with good arc resistance characteristics and a region with good current conduction characteristics. (3) The electrical contact according to claim 2, wherein the region with good arc resistance is formed by thermal spraying of a high melting point metal material onto the region with good current conduction properties made of silver. (4) The electrical contact according to claim 3, wherein the high melting point metal is tungsten. (5) The electrical contact according to claim 3, wherein the high melting point metal is molybdenum. (6) The electrical contact according to any one of claims 1 to 4, wherein the thermal spraying is plasma spraying. (7) Claims 1 to 5, in which the thermal spray bonding region is formed in a stepped notch formed in another region.
Electrical contacts described in any of the preceding paragraphs.