The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 22, 1986
Filed:
Apr. 27, 1984
Alfred E Feuersanger, Framingham, MA (US);
James P Drummey, Jr, Norwood, MA (US);
GTE Laboratories Incorporated, Waltham, MA (US);
Abstract
This invention provides a method of electric current welding in a flowing inert gas atmosphere of an electric feedthrough assembly for an electric lamp, and an apparatus for performing such welds. The method and apparatus are well suited to welding refractory metals, e.g., a molybdenum-titanium-nickel alloy feedthrough body a tungsten electrode for use in an alumina arc tube of a high-pressure sodium lamp, and a molybdenum lead-in wire pin. When the tungsten electrode is inserted into a receiving cavity in the feedthrough body and appropriate pressure applied, the electrical resistance of the solid-to-solid rough interface is greater than that of either the electrode pin or feedthrough so that application of an appropriate electrical pulse causes melting to occur only in the immediate vicinity of the interface whereby extensive recrystallization of the feedthrough body does not occur. A welding electrode in the form of a plate having a thickness approximately equal to the insertion depth of the lamp electrode into the feedthrough body has a cylindrical hole into which the feedthrough body is mounted so that the electrical current applied during the welding process flows primarily radially through the feedthrough body whereby the feedthrough body is further protected against extensive heating during the welding process. Provision of welding electrodes of substantial mass and high thermal conductivity draws heat from the feedthrough during and after the weld so that the feedthrough body is further protected from extensive heating.