GB2112312A

GB2112312A - Contact/base welded joint and method of producing same

Info

Publication number: GB2112312A
Application number: GB08230829A
Authority: GB
Inventors: Werner Minks
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1981-10-28
Filing date: 1982-10-28
Publication date: 1983-07-20
Also published as: DE3142692A1; GB2112312B

Abstract

In a welded joint consisting of a contact body (1) and a base (3) welded thereto, which are joined together by employing the so-called point-projection welding process, one or more projections (4) are embossed into the base. The supporting surface (2) of the contact body is plane and smooth. The basal area of the projections (4) is smaller than the supporting surface (2) of the contact body. In this way metal is prevented from squirting on to adjacent surfaces during the welding process. <IMAGE>

Description

SPECIFICATION Contact welded joint and method of producing same This invention relates to a contact welded joint between a contact body and a base using a welding projection, in particular for relay contacts.

It is already known, for example, from the technical journal "Elecktronik", no. 15, 1981, page 58, Fig. 9, and from DE-OS 1 920 620, to join contact bodies to a base by using the socalled point-projection welding process. In so doing, the supporting surfaces of the contact bodies are provided with one or two welding projections or with staggered rhombic welding embossments which serve the contacting and the fusing with the base during the electrical welding process.

Contact bodies are often cut in the required length from strips of contact material, and welded on to the base. In the case of strips with welding projections or embossments, the latter end at the cutting edges. Thus, during the welding process, it often happens that the welding zone extends to outside the basal area of the contact body. This often causes the squirting of molten metal particles during the welding process which easily melt or burn into the adjacent surfaces including the contact surface.

It is an object of the invention to avoid such squirting of molten metal particles while welding and to enable the use of strips of contact material which are as inexpensive as possible.

According to the invention there is provided a welded joint between a contact body and a base using a welding projection, in particular for relay contacts, wherein the one or each welding projection is so formed into the base that the basal area or areas are smaller than the supporting surface of the contact body, wherein the supporting surface of said contact body is smooth and plane, and wherein said one or more welding projections are located within the supporting surface of the contact body. Thus it is possible to use strips of contact material which do not have any welding projections or embossments but whose bottom surface is smooth and plane.

Therefore the manufacture of these strips is cheapened. This also needs less expensive weldable base metal for the contact bodies, because the embossments may be omitted.

Moreover, metal particles are substantially prevented from being squirted on to the contact surface. Also, the area around the contact body is practically kept free from burnt in molten metal beads fused thereon.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a side view of a base embodying the invention, and of a contact body prior to the welding process, Fig. 2 is a top view on to the base, Fig. 3 is a side view in section of the contact connection after the welding process, and Fig. 4 shows a further embodiment of the invention in a top view.

In Fig. 1, reference 1 indicates a square or rectangular contact body which is e.g. cut from a strip of contacts, whose supporting surface 2 is quite smooth and preferably of plane design. This contact body is intended to be welded on to a base 3 of a suitable material. Welding uses the socalled point-projection welding process, with the welding projection 4 formed, e.g. embossed or impressed into the base 3. This may be effected, for example, by a die mark 5.

The basal area 6 of the welding projection 4, see the shaded portion in Fig. 2, is smaller than the supporting surface 2 of the contact body 1 and reaches at no point the edge thereof. As a rule, the basal area 6 of the one or each welding projection 4 may correspond to 0.2 to 0.04 times the size of the supporting surface 2. Preferably, this value ranges between 0.1 and 0.07. For a round contact body 1 and a round welding projection 4, the diameter of the latter amounts to about one quarter of the diameter of the body 1. The circular bodies 1 may, for example, be punched out of the contact strip.

Fig. 3 shows the lenticular welding zone 7 which occurs during welding and which, at no point, extends beyond the contact body 1 or the supporting surface 2 thereof.

Fig. 4 shows a rectangular contact body 1 whose welding zone 7 has an elliptical shape, as indicated by the dashline. This shape can be formed by two or more round welding projections 4 arranged "in series", or else by one oblong, e.g.

elliptical welding projection as indicated by the dot- and dashline 8, or any other suitably shaped welding projections or embossments may be provided for on the base 3.

1. A welded joint between a contact body and a base using a welding projection, in particular for relay contacts, wherein the one or each welding projection (4) is so formed into the base (3) that the basal area or areas (6) are smaller than the supporting surface (2) of the contact body (1), wherein the supporting surface (2) of said contact body (1) is smooth and plane, and wherein said one or more welding projections (4) are located within the supporting surface (2) of the contact body (1).

2. A joint as claimed in claim 1, wherein the welding projections (4) are round, and in particular designed as a spherical cap.

3. A joint as claimed in claim 1, wherein the welding projections have an elliptical shape.

4. A joint as claimed in any one of claims 1 to 3, wherein the basal area (6) of said one or more welding projections (4) has a size ranging between 0.2 and 0.04, particularly between 0.1 and 0.07 times the size of said supporting surface (2) to be contacted.

5. A method of producing a contact welded joint in which a contact body, by the use of the point-projection welding process, is welded on to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Contact welded joint and method of producing same This invention relates to a contact welded joint between a contact body and a base using a welding projection, in particular for relay contacts. It is already known, for example, from the technical journal "Elecktronik", no. 15, 1981, page 58, Fig. 9, and from DE-OS 1 920 620, to join contact bodies to a base by using the socalled point-projection welding process. In so doing, the supporting surfaces of the contact bodies are provided with one or two welding projections or with staggered rhombic welding embossments which serve the contacting and the fusing with the base during the electrical welding process. Contact bodies are often cut in the required length from strips of contact material, and welded on to the base. In the case of strips with welding projections or embossments, the latter end at the cutting edges. Thus, during the welding process, it often happens that the welding zone extends to outside the basal area of the contact body. This often causes the squirting of molten metal particles during the welding process which easily melt or burn into the adjacent surfaces including the contact surface. It is an object of the invention to avoid such squirting of molten metal particles while welding and to enable the use of strips of contact material which are as inexpensive as possible. According to the invention there is provided a welded joint between a contact body and a base using a welding projection, in particular for relay contacts, wherein the one or each welding projection is so formed into the base that the basal area or areas are smaller than the supporting surface of the contact body, wherein the supporting surface of said contact body is smooth and plane, and wherein said one or more welding projections are located within the supporting surface of the contact body. Thus it is possible to use strips of contact material which do not have any welding projections or embossments but whose bottom surface is smooth and plane. Therefore the manufacture of these strips is cheapened. This also needs less expensive weldable base metal for the contact bodies, because the embossments may be omitted. Moreover, metal particles are substantially prevented from being squirted on to the contact surface. Also, the area around the contact body is practically kept free from burnt in molten metal beads fused thereon. Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a side view of a base embodying the invention, and of a contact body prior to the welding process, Fig. 2 is a top view on to the base, Fig. 3 is a side view in section of the contact connection after the welding process, and Fig. 4 shows a further embodiment of the invention in a top view. In Fig. 1, reference 1 indicates a square or rectangular contact body which is e.g. cut from a strip of contacts, whose supporting surface 2 is quite smooth and preferably of plane design. This contact body is intended to be welded on to a base 3 of a suitable material. Welding uses the socalled point-projection welding process, with the welding projection 4 formed, e.g. embossed or impressed into the base 3. This may be effected, for example, by a die mark 5. The basal area 6 of the welding projection 4, see the shaded portion in Fig. 2, is smaller than the supporting surface 2 of the contact body 1 and reaches at no point the edge thereof. As a rule, the basal area 6 of the one or each welding projection 4 may correspond to 0.2 to 0.04 times the size of the supporting surface 2. Preferably, this value ranges between 0.1 and 0.07. For a round contact body 1 and a round welding projection 4, the diameter of the latter amounts to about one quarter of the diameter of the body 1. The circular bodies 1 may, for example, be punched out of the contact strip. Fig. 3 shows the lenticular welding zone 7 which occurs during welding and which, at no point, extends beyond the contact body 1 or the supporting surface 2 thereof. Fig. 4 shows a rectangular contact body 1 whose welding zone 7 has an elliptical shape, as indicated by the dashline. This shape can be formed by two or more round welding projections 4 arranged "in series", or else by one oblong, e.g. elliptical welding projection as indicated by the dot- and dashline 8, or any other suitably shaped welding projections or embossments may be provided for on the base 3. CLAIMS

5. A method of producing a contact welded joint in which a contact body, by the use of the point-projection welding process, is welded on to a base, wherein the base (3) has at least one welding projection (4), with the basal area (6) or areas thereof being less than the supporting surface (2) of the contact body (1), wherein the contact body (1 ) has a plane supporting surface at (2), and is so placed on the welding or projections (4) that the basal areas (6) thereof, when looked at from above, are within the supporting surface (2), and wherein thereafter the welding is effected by a current impulse by simultaneously pressing together the base (3) and the contact body (1).

6. A contact welded joint substantially as described with respect to Figs. 1 to 3, or Fig. 4, of the accompanying drawings.

New claims or amendments to claims filed on 7/2/83 New or amended claims

7. A method of welding an electrical contact to a contact support such as a relay contact strip, wherein the contact has a body with a plane surface which is to be welded to the contact strip, wherein the contact strip has one or more welding projections at the region to which the contact is to be welded, the area of the projection or projections being less than the area of the contact's flat surface, the area of the projection or projections lying in the range of 0.1 to 0.07 times the area of the plane surface, and wherein the method involves so placing the contact on the strip that the welding projection or projections is or are wholly within the area of the contact's plane surface, and thereafter effecting the welding by the point-projection process by the application to the contact and the strip of a current impulse while the contact and the strip are pressed together.