W.c. Heraeus Gmbh

W.c. Heraeus Gmbh & Co Kg

Heinrich Wolf

Dieter Feldmer

Rudolf Schnabl

Holger Eisentraut

For the profile kneading of workpiece in strand from (semiproducts) which are transported along a central axis into a working station (profile kneading machine) at least two dies situated opposite one another in pairs for working on the surface of the workpiece are driven by rams at their extremity remote from the axis; the rams are driven radially toward the axis by rolls (cylinders, balls) moving on a circular path relative to outer guiding surfaces of the rams; at the same time at least two pairs of dies, whose radial driving directions are displaced from one another by a given angle (90.degree.), are driven successively by the rolls in a radial direction by means of the guiding surfaces of the rams; the edge length of the dies in each working step is greater than the targeted edge length of the workpiece (semiproduct) that is to be worked.

Method for profile-kneading workplaces

Intermediate material in the form of a metal strip with a contact area is provided with a projection on the bottom surface of its core area, i.e., on the surface to be joined to a contact carrier strip of copper or a copper alloy. The bottom surface of the strip facing the contact carrier strip is plated with a material which consists essentially of silver, and the melting point of the core area of the metal strip is above the melting point of silver. For the production of a semifinished product for electrical contacts, the metal strip is welded by its silver-coated bottom surface to the contact carrier strip, consisting essentially of copper. The silver from the coating on the core area of the metal strip and the copper from the contact carrier strip mix with each other and thus form an alloy which corresponds or is very close to the eutectic alloy with 28 wt. % of copper and the remainder of silver.

Welding process

To manufacture a starting material for electrical contacts, such as relay contacts, a contact sandwich in the form of a metal strip made of a material of good electrical conductivity is bonded to a contact support strip consisting essentially of copper by resistance welding. The bonding surface of the metal strip has wales or ridges running lengthwise, the crests of the ridges being tapered in cross section and being provided with a coating consisting essentially of silver. To produce an electrical contact, the ridges are pressed against a copper contact support and a high heat is produced at the crests of the ridges by a welding circuit. This results in the melting of the silver coating, which is forced between the ridges by the pressure applied through the electrodes of the welding circuit, where it forms a silver-copper alloy with a melting point close to the eutectic. The surface of the strip which is to be the working contact is disposed on the side of the strip opposite the side provided with the ridges.

Manufacture of electrical contacts

To permit direct bonding of a composite electric contact-and-bonding material to a carrier, such as a reed, magnetic strip, or the like, by thermo-electric heating, the side of the contact-and-bonding material is formed with projections, preferably projecting ridges, ribs, or beads, and a bonding or solder material in wire form is adhered, by rolling on to the valley between the projecting ridges, the bonding or soldering material leaving space free between adjacent ridges or ribs and not filling the entire recess, but projecting outwardly at least as far as the projections or ridges, and preferably slightly therebeyond. The soldering or bonding wire may have round or polygonal, preferably triangular cross section with a pointed tip extending outwardly to provide for concentration of heat upon resistance heating the contact material against the carrier strip.

Growing community of inventors

Hailer, Germany

Heinrich Wolf