Method of making diffusion bonded and superplastically formed structures

Abstract

An improvement is disclosed to the method of making metallic structures from a plurality of stacked workpieces or blanks by joining first portions, preferably by diffusion bonding, of the stack and by clamping the joined stack at its periphery between forming members and superplastically forming second portions of said plurality of stacked blanks by the selective application of fluid under pressure. The improvement is a method of coupling the fluid to the second portions of the stack which comprises providing a first port through one of the outer blanks at the periphery of the stack. At least one stopoff path is provided for coupling the first port to the second portions of the stacked blanks, which are to be superplastically formed. A second port is provided in one of the forming members, which couples the first port to a source of pressurized fluid. Where there are at least three blanks in the stack, a slot is provided within the inner blank or blanks of the stack coupling the first port to the at least one stopoff path. Additionally, a hollow tubular member may be inserted into the slot. A hole is drilled through one wall of the tubular member, thus, coupling the interior thereof to the first port. In another embodiment, a groove in the second forming member aligned with the first port is provided, such that upon the application of pressure to the first port, the second blank is expanded within the groove forming an additional passageway coupling the first port to the at least one stopoff path.