Mandrel and method of manufacturing same

Details Mandrel and method of manufacturing same Mandrel and method of manufacturing same

1976-06-04

1977-09-20

Larson, Lowell A.

Wireworking

Article making or forming

Electric lamp or electric space discharge device electrode

204 44, B21F 304

Patent

active

040490246

ABSTRACT:
A mandrel and a method for its manufacture and its use in manufacturing filament coils for electric lamps is disclosed. The mandrel, having a base core containing iron, is protected from diffusion of iron into a filament wire wound thereabout by a first coating of copper and a second coating of tungsten over the first, base metal. The process of coating the tungsten over the copper coating is improved by employing small amounts of copper ion contaminant in the electroplating solution. After a filament wire is wound around and annealed over this mandrel, the mandrel is selectively dissolved leaving the shaped filament coil, substantially free of extraneous metal impurities.

REFERENCES:
patent: 2145241 (1939-01-01), Armstrong et al.
patent: 2145745 (1939-01-01), Armstrong et al.
patent: 3662789 (1972-05-01), Koo et al.

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