JPS5913811B2 - Manufacturing method of switch movable body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a switch movable body, and more specifically, to a method of manufacturing a switch movable body that is moved by a magnetic field to perform a switch operation.

As an example in which the above-mentioned switch movable body is used, the first
There is a switch as shown in the figure.

In this switch, a switch movable body made of a permanent magnet made of porous sintered body is used to electrically conduct or cut off two sets of fixed electrodes 3a and 3b and 4a and 4b made of soft magnetic material. 1 is the fixed electrode 3 a t 3 b
4a and 4b are moved at high speed by a magnetic field coil (not shown) and brought into colliding contact with each other by rare and magnetic attraction.

In order for the movable body 1 to move at high speed due to the action of the magnetic field coil, the movable body 1 has fixed electrodes 3a, 3b or 4a, 4.
impacting contact with b.

By the way, although soft magnetic materials have a high degree of rigidity, permanent magnet materials generally have brittle properties, and rare earth cobalt magnets, which have excellent magnetic properties, are particularly brittle.

Therefore, the switch movable body 1 made of a permanent magnetic material is subject to chipping during use, and the chipping limits the life of the switch.

In order to suppress this chipping,
No. 11 Patent Application No. 12799/1979 ``Switch''
submitted.

This method involves forming a soft metal layer such as nickel, copper, or tin on a permanent magnet, and then forming a hard contact layer such as rhodium or tungsten on the metal layer. It diffuses heat.

According to this, since the soft metal layer absorbs the impact force when the contact layer collides with the fixed electrode, the permanent magnet is less likely to crack or chip, and as a result, chipping can be reduced.

By the way, in order to prevent this chipping, it is necessary to make the soft metal layer sufficiently thick to at least 50 μm or more, but in general, plating treatment is suitable for depositing metal thickly.

However, when nickel or tin, in particular, is used as a soft metal and is plated on a permanent magnet to a thickness of, for example, 50μ or more, the soft metal swells by 11 times when thermally diffused! The results of the experiment showed that 1 is generated and peeling becomes easier.

The present invention provides a method for manufacturing a switch movable body in which the soft metal layer is sufficiently thick for shock absorption, has an effective chipping prevention effect, and has effective adhesion.

In the present invention, a movable body made of a porous sintered permanent magnet is enclosed in a container, and a fixed electrode made of a soft magnetic material is sealed at both ends of the movable body, and the movable body is attached to the enclosed end of the fixed electrode. The switch is electrically opened and closed by magnetically adsorbing collision contact with the permanent magnet, and the entire surface of the permanent magnet is covered with a soft metal layer that absorbs the collision energy at the time of the collision contact, and the soft metal layer is coated with a soft metal layer. In the method for manufacturing a switch movable body, a hard contact metal layer is formed on the permanent magnet and the soft metal layer, and an adhesion layer is formed between the permanent magnet and the soft metal layer by heat diffusion between the two. Formed with a silver plating film of 50μ or more, and before forming the silver plating film, a base layer made of a soft metal film having a thickness that allows the permanent magnet and the silver plating film to thermally diffuse and to which silver can be attached. It is characterized in that it is formed on the permanent magnet by dry coating.

In the present invention, as the base film to be formed before depositing the silver plating film, for example, nickel is deposited by dry coating such as sputtering, preferably to a thickness of 10μ or less, so that the permanent magnet and the silver plating film can be thermally diffused. is used.

The use of this base film has the advantage that the electrolyte will not be mixed into the permanent magnet (porous body) when silver is plated on the permanent magnet in the next step.

Tin, copper, etc. may be used for the base film.

The silver plating film is formed on the entire surface of the switch movable body, that is, on the surface in contact with the fixed electrode and on the surface not in contact with it, so that the former covers the latter.

Since the plating film on the surface not in contact with the fixed electrode supports and reinforces the plating film on other surfaces, it is thought that chipping of the contact surface and resulting peeling are less likely to occur.

The thickness of the silver plating film is 50μ to prevent chipping.
The above shall apply.

As a plating method, known silver electrolytic or electroless plating is used.

When plating small moving objects, it is difficult to handle the materials using general plating methods, so the materials to be treated are placed in a stainless steel cage, and the basket is connected to a power source for plating. The Palermecki method is useful.

If the permanent magnet is a rare earth or cobalt magnet, the movable body on which the silver plating film is formed by the above method has a magnetization of 500 to 850.
C., preferably 700 to 820.degree. C., to cause diffusion between the silver plating film and the permanent magnet.

This diffusion ensures the adhesion of the plating film and also slightly reduces the film thickness.

If the diffusion temperature is less than 500°C, diffusion will not proceed sufficiently, and if it exceeds 850°C, the properties of the permanent magnet will deteriorate significantly.

Diffusion treatment is performed in vacuum or in an inert gas atmosphere.

The reason for this is that the oxide layer on the surface impairs contact performance or impairs adhesion when a film is further formed.

The object of the present invention is that since the fixed electrode has a slight rigidity, the collision energy of the movable body is not sufficiently absorbed by the fixed electrode side, and chipping etc. occur on the movable body covering part. It's a switch.

In the present invention, since the collision energy when opening and closing the switch is extremely high, noble metal contacts lack strength, wear resistance, and impact resistance, so hard metals such as rhodium and tungsten are used for the contact surfaces.

It is also important that a considerable thickness of silver plating remains in the final product, and that the adhesion strength of the film is increased by diffusion.

Next, if necessary, a hard contact metal such as rhodium or tungsten, which is commonly used as a contact, is formed on the silver plating film by sputtering or plating.

The present invention will be described below based on Examples and Comparative Examples.

In this example and comparative example, rare earth cobalt magnet SmCo
5 was sintered into a cylindrical shape with a diameter of 3.5 mm and a thickness of 2 mm, and this sintered body was subjected to the surface treatment described below to form the movable body 1.

Incidentally, this movable body 1 is actually applied to a switch as shown in FIG.

This switch has a movable body 1 enclosed in an insulating container 2 such as a glass tube, and a soft magnetic material such as 5
Two sets of fixed electrodes 3a + 3b and 4a r consisting of 270
4b and are formed by sealing each other.

Then, the switch is connected to two sets of fixed electrodes 3a by the coil magnetic field.
, 3b and 4 a t 4 b as A, A' or B respectively.

The movable body 1 is simultaneously magnetized in the direction (1) and moved left and right by the magnetic force of repulsion and attraction, and the movable body 1 is attracted to one of the fixed electrodes, so that the fixed electrodes 3a and 3b or 4a and 4b
becomes conductive via the movable body 1, and a switching operation is performed.

[Comparative example]

A nickel plating film was formed on the surface of the permanent magnet to a thickness of 50 μm (FIG. 2A), and this was heated in a vacuum at 750° C. for 1 hour for diffusion (FIG. 2B).

As understood from this comparative example, nickel appears to be in close contact with the permanent magnet before being diffused, but when heated, it "bulges" as shown in Figure B.

This blistering phenomenon is thought to be caused by thermal stress, but only partially occurred when the plating thickness was 50 μm.

However, as the plating thickness increased to 60 μm, 70 μm, etc., this blistering phenomenon occurred everywhere and became more severe.

Further, when the thickness was 50 μm or less, 11 bulges 11 hardly occurred.

[Example 1] First, a nickel base layer of 6 μm was formed on the surface of the permanent magnet by sputtering, and then a silver plating film was formed on the base layer to a thickness of 50 μm. Therefore, it was heated at 750°C for 1 hour in a vacuum (Fig. 3B).
.

Incidentally, the silver plating films of Examples 1 and 2 were formed under the following conditions.

Plating solution composition' A g CN 50 F! / 1
3? KCN60 g/it K2 CO35
9/l.

KOH 10g/l Bath temperature: room temperature Current density = 0.2-0.3 A/dm Stirring:
Yes Anode: Silver As is clear from this example, in the movable body according to the present invention, nickel is used as the base layer and a silver plating film is used as the metal layer that acts as a shock absorbing member. Even if the plating thickness is 50μ or more, a plating film with good adhesion can be obtained without causing blistering I+.

Also, of course, if a hard contact layer of tungsten, rhodium, etc. is formed on the movable body and applied to a switch as shown in Figure 1, silver has a lower hardness than nickel and must be plated sufficiently thickly. Since the switch is movable, chipping can be further reduced and the life of the switch can be extended.

As described above, according to the present invention, a movable body having a sufficient chipping prevention effect and a long life can be obtained, and the effect is extremely remarkable.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an example of a switch in which a movable body manufactured by the method of the present invention is used. Figure 2A. B is a micrograph showing the structure of a cross section of a conventional movable body, where A shows the state before diffusion and B shows the state after diffusion. FIG. 3 is a micrograph showing the structure of a cross section of a movable body according to an embodiment of the present invention, where A shows the state before diffusion and B shows the state after diffusion. [Explanation of symbols] 1...Movable body, 2...
- Insulating container, 3a, 3b, 4a, 4b...Fixed electrode.

Claims (1)

[Claims] 1. A movable body made of a porous sintered permanent magnet is enclosed in a container, and a fixed electrode made of a soft magnetic material is sealed at both ends of the movable body, and the movable body is made of a porous sintered permanent magnet. A switch that is electrically opened and closed by colliding contact with the enclosed end by magnetic attraction,
The entire surface of the permanent magnet is covered with a soft metal layer that absorbs the collision energy at the time of collision contact, and a hard contact metal layer is formed on the soft metal layer, and the permanent magnet and the soft metal layer are formed on the soft metal layer. In the method for manufacturing a switch movable body in which an adhesion layer is formed between the layers by thermal diffusion of both layers, the soft metal layer is formed with a silver plating film having a thickness of 50 μ or more, and before forming the silver plating film, A movable switch body characterized in that a base layer made of a soft metal film having a thickness that allows thermal diffusion of the permanent magnet and the silver plating film and to which the silver plating can be attached is formed on the permanent magnet by dry coating. manufacturing method.