Method of dimensionally stabilizing a tungsten filament
AssigneeGeneral Electric Company
InventorsRonald J. Olwert, John T. Pastir
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Abstract
A method of establishing coil dimensional stability by thermally stress relieving the tungsten filament prior to mounting in a lamp. The filament is manipulated into the desired position by coiling it first around a primary mandrel, then a retractable secondary mandrel. After the secondary mandrel is removed, the filament is held in place by a pair of electrical contacts. A current is passed through the primary coil, which heats the tungsten and causes it to recrystallize. The recrystallization provides the desired dimensional stability.
Claims23
A method of dimensionally stabilizing a tungsten filament prior to installation in a lamp comprising the steps of:
- providing a tungsten filament which has been wound around a primary mandrel to provide a primary coil in contact with said primary mandrel,
- contacting said filament-wound primary mandrel with a first electrical contact adjacent a first end of said filament and with a second electrical contact adjacent a second end of said filament,
- inducing a current in the primary mandrel between said first and second electrical contacts, said current being effective to heat the tungsten filament wound around and in contact with said primary mandrel to a temperature sufficient to recrystallize tungsten therein, and
- maintaining the current until the tungsten filament at least partially recrystallizes.
Dependencies are inferred from the claim text.