William G Mcgee

US Patent:

54710316, Nov 28, 1995

Filed:

Nov 29, 1993

Appl. No.:

8/158331

Inventors:

J. R. Dailey - Washington DC
William F. McGee - Decatur AL
Daniel J. Rybicki - Huntsville AL

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

B23K 1000

US Classification:

21912146

Abstract:

A method and apparati are presented for non-chamber root side purging in fusion welding of oxygen reactive metals which require that the molten weld zone and local solid areas of the weld seam remaining at high temperatures be shielded from normal atmosphere to prevent degradation of the welded area. The apparatus provides an inert atmosphere to the root side of a weld joint through a porous medium whereby the jet-like thrust of the plasma arc actually draws the continuously supplied inert atmosphere into the path of the molten or high temperature solid weld zone. The porous medium is configured so it can be placed at the borders of the weld seam and substantially parallel to the seam without restricting the view of the root side of the seam. The inert gas is dispersed evenly through the porous media and across the weld seam, at the point of arc penetration and in front of and behind the arc. The apparatus can be constructed so as to limit the amount of inert gas flow and can be mobile and travel synchronously with the welding arc.