Bimetallic contact element for electrical switch - comprises noble metal core which is cast in centre of half toric crown of less expensive metal

摘要

A bimetallic switch has a contact using 60-70% less precious metal than normal and has a conductor leaf (4) to which one end of a wire is soldered under pressure. The wire has a core (11) of precious metal or alloy such as silver, and an outer layer (12) of cheap metal or alloy such as copper. The wire is snipped (2-2) to leave a stub which is pressed such that the copper forms a half-torus (120) with the silver spreading out to form a part spherical or elliptical cover (110) over the torus. The contact thus formed uses a minimum of precious metal to the maximum advantage over the maximum contact area.