Mark J Pruitt

US Patent:

58902856, Apr 6, 1999

Filed:

Aug 23, 1996

Appl. No.:

8/702288

Inventors:

Mark O. Pruitt - Florissant MO
Christopher A. Ross - University City MO

Assignee:

McDonnell Douglas Corporation - St. Louis MO

International Classification:

B23P 1500

US Classification:

2988972

Abstract:

A method for forming a hollow structure having a predetermined shape from a sheet of superplastic material. The sheet is initially formed into a preform configuration. A reusable fluid inlet tube is placed in the preform configuration to define a port in fluid communication with the interior portion of the preform configuration. The preform configuration is disposed in a containment die, which defines a cavity having the predetermined desired shape. Force is applied to the containment die to temporarily seal the edges of the preform configuration without the use of welding or diffusion bonding. Once its edges are sealed, the preform configuration becomes a gas-tight envelope capable of holding fluid that is introduced through the fluid inlet tube. Fluid (e. g. , argon) is fed through the tube to apply internal pressure to the gas-tight preform configuration under superplastic conditions (including appropriate heating) while it is still being held in the containment die so that it superplastically expands in the die cavity (deforms) into a hollow structure having the predetermined shape. The hollow structure may be an aeronautical member, e. g.