JPS6161306A - Contact mechanism - 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 (a) Field of Industrial Application The present invention relates to a contact machine (in other words, a contact structure in which a noble metal layer is formed on the surface of a contact base material).

(B) Prior art and its problems Conventionally, in order to obtain electrical conductivity and corrosion resistance of the contact, it has been widely practiced to clad or plate the surface of the contact base material with a noble metal. In particular, in contact mechanisms with low contact loads, contacts coated with, for example, pure gold plating or pure gold cladding are used in order to maintain contact stability.

However, since pure gold has low hardness, it is prone to sticking and transfer, and has short contact life.

Therefore, in order to extend the contact life, which is the drawback mentioned above, for example, the surface of the contact base material is coated with a highly hard gold-silver alloy cladding or gold-cobalt alloy plating to prevent sticking and transfer while maintaining the stability of contact resistance. are doing.

However, in contact mechanisms with low contact loads, the high hardness of precious metals makes it difficult for plastic deformation of the contact surfaces to occur.
The disadvantage is that the contact area is small and the contact resistance is unstable.

(c) Purpose of the Invention The purpose of the present invention was made in view of the above-mentioned drawbacks, and is to provide a contact machine (11j) having a long contact life and excellent contact stability.

(d) Structure of the Invention In order to achieve the above object, the contact mechanism according to the present invention has the following features:
In a contact mechanism that opens and closes by touching and separating the contacts, there is a hardness difference between the hardness of the precious metal layer formed on the surface of one contact base material and the hardness of the precious metal layer formed on the surface of Ikegata's contact base material. This is the configuration provided.

(E) Description of Embodiments Embodiments according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention, in which a hard plating layer 3 of gold-cobalt alloy is formed on the surface of a contact base material 2 provided on one contact piece 1, and This is a case where pure gold soft plating WJ6 is formed on the surface of the contact base material 5.

The hardness of the hard plating layer is suitably 100 to 1508 on the Knoop hardness, and the hardness of the soft plating layer is suitably 50 to 90Hk on the Knoop hardness. If the Knoop hardness of the hard plating layer is 150 or more, the contact resistance becomes unstable and the soft plating layer suffers from increased wear. On the other hand, if the Knoop hardness of the soft plating layer is 508 or less, adhesion and transfer may occur. This is because there is a problem in that it is more likely to occur.

Next, an experimental example of the contact mechanism according to the above embodiment will be explained.

Experimental Example 1 This experimental example relates to the contact stability of the contact mechanism according to the present invention.

In the contact mechanism according to the present invention, the surface of the base material of the movable contact is plated with a gold-cobalt alloy of high hardness to form a hard plating layer, while the surface of the base material of the fixed contact is plated with pure gold of low hardness to form a soft plating layer. It is constructed by forming layers.

For reference, in addition to the products of the present invention, experimental results of comparative products in which gold-cobalt alloy was plated on the base material surfaces of fixed contacts and movable contacts are also shown. The Knoop hardness of the noble metal layer of the present invention product and the comparative product is as shown in Table-1. Further, the hardness of the noble metal plating layer made of gold-cobalt alloy was adjusted by adjusting the pH of the plating bath and the content of cobalt salt.

The numbers in parentheses in Table 1 are the cobalt eutectoid rate (%
), and when the cobalt eutectoid rate is (0%), it indicates pure gold plating.

The measurement results of the correlation between the contact load (g) and the contact resistance (IIIΩ) of the contact mechanism under the above conditions are shown in FIGS. 2 to 5.

Comparison product 1 (Fig. 3) and comparison product 2 (Fig. 4) both have hardness of the precious metal plating layer on the fixed contact and the movable contact of 1808 or more, and have a high overall contact resistance and a low contact resistance. Since there is a large variation in contact resistance in the load range (approximately 4 g), it can be seen that the contact state is unstable.

Comparative product 3 (Fig. 5) has the following characteristics compared to comparative products 1 and 2 described above.
Although it shows a relatively stable state, it shows high contact resistance overall.

However, the product of the present invention (FIG. 2) has much smaller variation in contact resistance than the comparative product.

Moreover, in the low contact load region where the contact load is approximately 4g,
Since the contact resistance is 50 mΩ or less, it can be seen that the contact resistance is stable from the high contact load region to the low contact load region.

From the above experimental results, it was found that the contact points (some structures) of the product of the present invention had excellent contact stability.

Experimental Example 2 This experimental example concerns the contact life of the contact optic according to the present invention.

In this experiment, the contact life was investigated by continuously opening and closing a contact mechanism with a structure similar to that of Experiment 1. The experimental conditions and results are shown in Table 2.
Shown below.

Table 2 From the above experimental results, it can be seen that the contact mechanism according to the present invention has excellent adhesion resistance and transfer resistance, and therefore has a long contact life. Furthermore, since no significant change was observed in the contact resistance before and after the experiment, it was found that excellent contact stability could be maintained for a long period of time.

FIG. 6 shows a second embodiment of the present invention, in which a noble metal plating layer is formed on the surface of the contact base material provided on the contact pieces in the first embodiment, whereas the contact pieces 1 and 4 are This is a case where noble metal cladding layers 3 and 6 are formed on the contact surfaces of contact base materials 2 and 5 provided on the contact base materials 2 and 5.

In addition, the noble metal according to the present invention includes gold-cobalt alloy,
It may be a gold-silver alloy, a gold-nickel alloy, a gold-palladium alloy, etc., and the hard plating or soft plating may be either a fixed contact or a movable contact. Furthermore, it goes without saying that the noble metal plating layer and the noble metal cladding layer may be combined as appropriate.

(F) Effects of the Invention As is clear from the above explanation, according to the contact mechanism according to the present invention, the hardness of the noble metal layer formed on the surface of one contact base material is the same as the hardness of the noble metal layer formed on the surface of the other contact base material. Since the hardness of the noble metal layer is higher than that, sticking and transfer of the noble metal layer is less likely to occur than in the case of a contact mechanism in which either the hardness of the noble metal layer or both are low, and the contact life is extended.

Moreover, since the hardness of the other precious metal layer is lower than that of the other, when the contacts are brought into contact and separated, plastic deformation occurs on the contact surface of the other precious metal layer, increasing the contact area and stabilizing the contact resistance. This has the effect of improving stability.

[Brief explanation of the drawing]

FIG. 1 shows a cross section 1lfD#If of the first embodiment according to the present invention.
2 to 5 are graphs showing the measurement results for Experimental Example 1 of the contact mechanism according to the present invention, and FIG. 2 is a graph for the product according to the present invention, and FIGS. FIG. 5 is a graph diagram of comparative products 1 to 3, and FIG. 6 is a cross-sectional perspective view of a second embodiment of the present invention. Patent applicant: Tateishi Electric Co., Ltd. Agent
Patent attorney Blue and white 葆 Two idiots Figure 1 Figure 6 Figure 2 υ 1υ Sゑ鴇1 (9) Figure 3 tj54 Figure 5 Item N, Genus 1 (9)

Claims (3)

[Claims] (1) In a contact mechanism that opens and closes by connecting and separating contacts, there is a difference in hardness between the hardness of the noble metal layer formed on the surface of one contact base material and the hardness of the noble metal layer formed on the surface of the other contact base material. A contact mechanism characterized by having a difference. (2) The contact mechanism according to claim 1, wherein the noble metal layer is a noble metal plating layer. (3) The contact mechanism according to claim 1, wherein the noble metal layer is a noble metal cladding layer.