Rivet-type contact and method for manufacturing the same

Abstract

A rivet-type contact of the present invention has a head part made of a contact material, and a leg part narrower than the head part in width and configured to be deformed at fixation. The leg part includes a flange part larger than the leg part in diameter, in an end part of the side of the head part, the flange part is embedded in the head part such that a lower end surface of the flange part and a lower end surface of the head part become approximately flat, and a length (l) between an endmost part of the flange part and a starting point of the leg part satisfies l<L with respect to a length (L) between an endmost part of the head part and the starting point of the leg part. Specifically, it is favorable that l satisfies 0.5 L≤l≤0.9 L with respect to L.

Claims

1. A rivet-type contact comprising: a rivet having a head part and a leg part, wherein the head part and the leg part share a longitudinal axis; the head part is made of a contact material and having a height Y in the direction of the longitudinal axis and having a width, wherein the contact material comprises Ag or an Ag alloy; the head part is formed from a deformed billet made of the contact material; and the leg part having a narrower width than that of the head part, the leg part deformed such that a diameter of the leg part becomes larger than that of a hole drilled in a base when the rivet is fixed to the base and comprises Cu or a Cu alloy, wherein when the rivet-type contact is fixed to the base, the leg part has, in an end part of a side of the head part, a flange part having a larger width than that of the leg part, and having a smaller width than that of the head part, the flange part preventing the contact material from coming into contact with the hole of the base, the flange part is embedded in the head part to a depth X in the direction of the longitudinal axis, such that a lower end surface of the flange part and a lower end surface of the head part are approximately flat and coplanar, and a ratio X/Y is between 1/3 and 1/10.

2. A rivet-type contact comprising: a rivet having a head part and a leg part, wherein the head part and the leg part share a longitudinal axis; the head part made of a contact material and having a height Y in the direction of the longitudinal axis and having a width, wherein the contact material comprises Ag or an Ag alloy; the head part is formed from a deformed billet made of the contact material; and the leg part having a narrower width than that of the head part, the leg part deformed such that a diameter of the leg part becomes larger than that of a hole drilled in a base when the rivet is fixed to the base and comprises Cu or a Cu alloy, wherein when the rivet-type contact is fixed to the base, the leg part has, in an end part of a side of the head part, a flange part having a larger width than that of the leg part and having a smaller width than that of the head part, the flange part preventing the contact material from coming into contact with the hole of the base, the flange part is embedded in the head part to a depth X in the direction of the longitudinal axis, and a ratio X/Y is between 1/3 and 1/10, such that an undersurface of the flange is not covered by the contact material and the uncovered undersurface of the flange and an adjoining portion of the leg form a single material contact surface for contacting a surface to be riveted.

3. The rivet-type contact according to claim 1, wherein the contact material of the rivet-type contact is an Ag alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram for describing occurrence of caulked wrinkles in a conventional two-layer rivet-type contact.

(2) FIG. 2 is a diagram for describing a configuration of a two-layer rivet-type contact according to the present invention.

(3) FIGS. 3(a) to 3(c) are diagrams for describing examples of configurations of the two-layer rivet-type contact according to the present invention.

(4) FIGS. 4(A) to 4(C) are diagrams for describing a process of manufacturing the rivet-type contact of the present embodiment.

(5) FIG. 5 is a diagram illustrating durability test results of the present embodiment and a comparative example.

(6) FIG. 6 is a photograph of a head part (contact material) of the comparative example after the durability test.

(7) FIGS. 7(a) and 7(b) are diagrams for describing configurations of the conventional two-layer rivet-type contact.

DESCRIPTION OF EMBODIMENTS

(8) Hereinafter, a favorable embodiment of the present invention will be described. FIG. 4 illustrates a process of manufacturing a rivet-type contact according to the present embodiment. First, a columnar first billet (dimensions: ϕ 1.4 mm, 0.87 mm) was cut from wire of an Ag alloy (Ag—SnO.sub.2—In.sub.2O.sub.3 alloy), and a columnar second billet (dimension: ϕ 1.4 mm, 1.10 mm) was cut from wire of Cu.

(9) Then, as illustrated in FIG. 4(A), the first billet and the second billet were layered, inserted into a joining dice, and pressure-welded, so that a joined material was obtained. The joining dice is made of cemented carbide and has a bore diameter of ϕ 1.45 mm. Further, a load for joining was 0.9 ton.Math.f. Note that, in the present embodiment, the first billet and the second billet were inserted into the joining dice, and the joining was performed. This is because adequate constraint is provided to the joined material in a cross direction so that the joined material is not excessively deformed, in addition to convenience that molding processing can be performed without any change. Here, the bore diameter of the dice into which the first billet and the second billet are inserted is favorably larger by 0.05 to 0.15 mm than the diameter of the billets.

(10) Next, a joining punch was set on the joining dice, and the joined material was processed into a rivet shape, as illustrated in FIG. 4(B). The joining punch is made of cemented carbide, and has a disk-shaped space with a curved side surface (dimensions: an upper surface ϕ 1.68 mm, a lower surface ϕ 1.8 mm, and the height 0.7 mm). In this process, the joined material was pressed into the space of the joining punch from a lower side of the joining dice at once, and the first billet part was deformed into a head part shape. At this time, a joined surface of the joined material was deformed following the deformation of the first billet part, and formed an outer shape of a flange part.

(11) After the creation of the rivet-type contact with a molding, the joining punch was moved, and an upper surface of the head part was pressed and molded, as illustrated in FIG. 4(C). Dimensions of the rivet-type contact manufactured as described above are as follows: the head part has ϕ 2.5 mm and the thickness of 0.35 mm, the leg part has ϕ 1.5 mm and the length of 0.8 mm, and the flange part has ϕ 2.0 mm and the height of 0.1 mm on the lower end surface of the head part.

(12) Then, the durability was evaluated with respect to the manufactured rivet-type contact. Durability evaluation was performed such that the rivet-type contact was attached to a hinge-type alternating current general relay, as a fixed contact, opening/closing operations were repeated in a state of a current load, and the number of times of opening/closing of the durability life until occurrence of failure was measured. In this evaluation test, as a comparative example, a rivet-type contact in which an Ag alloy that has the same shape as FIG. 7(a), and is the same as the present embodiment was joined with a Cu base material as the contact material was tested. Test conditions in the evaluation test are as follows.

(13) Test Voltage: AC 100 V

(14) Test Current: 10 A

(15) Load: Resistance load

(16) Frequency of opening/closing: ON for one second/OFF for 10 seconds

(17) Contact force: 1.96×10.sup.−1N (20 gf)

(18) Movable Contact Dimensions: ϕ 3.0 mm×t 0.35 mm

(19) The durability test was conducted with a plurality of relay test machines, and the numbers of times of opening/closing of the durability life, at which failure occurred in each relay, was plotted on a Weibull probability paper. Results are illustrated in FIG. 5. From FIG. 5, a characteristic life of each rivet-type contact was about 340,000 times in the present embodiment, and about 300,000 times in the comparative example. Therefore, it has been confirmed that the rivet-type contact of the present embodiment is excellent in the durability life.

(20) FIG. 6 is an enlarged photograph of a head part of the rivet-type contact of the comparative example after the durability test. In an end part of the contact material, the consumption is severe, and separation of the contact material is seen.

INDUSTRIAL APPLICABILITY

(21) The two-layer rivet-type contact according to the present invention suppresses the separation/dropout of the contact material in the use process. In the present invention, improvement of the durability life is added to the primary characteristic of the two-layer rivet-type contact, which is the decrease in the amount of use of the contact material and the suppression of the member cost.