| abstract |
A superplastically formed, diffusion bonded sandwich structure (30) having integral metal hardpoints (40), made by joining two superplastic metal core sheets (36) together into a core pack (38) by welding or diffusion bonding along a pattern of lines which form junction lines between the core sheets (36) when the pack (38) and metal inserts (40) are interposed between the face sheets (32, 34) and the core (38). All of the sheets in the pack (30) are sealed together around an outside peripheral edge to create a gas tight envelope. The pack (30) is heated to superplastic temperatures in a cavity of a die, and the top and bottom face sheets (32, 34) are diffusion bonded to top and bottom surfaces of the metal inserts (40) by application of heat and pressure from top and bottom inner surfaces of the die cavity. While at superplastic temperatures, the pack (30) is inflated by gas pressure against inside surfaces of a die to form an expanded metal sandwich structure (30) having integral webs (36) and having integral hardpoints (40) formed by the metal inserts (40). After forming, the gas pressure is reduced to near atmospheric, the die is opened and the part (30) is removed from the die. |