Patent ID: 6478213
Filing Date: 2002-11-12
Classification: B23K,F16L

Abstract:
A method of fabricating a multi-tubular structure without the use of a brazing flux, comprising the steps of:providing an inner tube; providing a bottom outer tube having a flared upper end; providing a top outer tube; providing a mass of braze material having a braze-material melting point; assembling a brazing assembly having no flux and having a brazing fixture with a movable portion and a stationary portion, the inner tube mounted to the stationary portion of the brazing fixture, the bottom outer tube overlying the inner tube, the top outer tube overlying the inner tube, wherein the top outer tube and the bottom outer tube are coaxial along a tube axis but longitudinally spaced apart along the tube axis, and wherein one of the bottom outer tube and the top outer tube is mounted to the movable portion of the brazing fixture and the other is mounted to the stationary portion of the brazing fixture, and the mass of braze material overlying the inner tube and residing within the flared upper end of the bottom outer tube; brazing the brazing assembly in a vacuum, the step of brazing including the steps of heating the braze material to a temperature above the braze-material melting point, and simultaneously moving the movable portion of the brazing fixture so the top outer tube and the bottom outer tube move toward each other along the tube axis toward an adjacent, end to end relation with each other.