Apparatus and a method for fabricating superplastically formed structures
AssigneeBritish Aerospace PLC
InventorsBrian Ginty, Stephen H. Johnston, Duncan R. Finch
Life of this patent
Estimating the term…
Abstract
A superplastic forming apparatus is described in which a blank of superplastic material is formed onto a die located in a pressure cavity. The die, which is preferably made of ceramic material, is removable from the cavity and requires no special connections for gas or vacuums ducts and therefore is cheap to manufacture. The use of a separate die also allows accurate monitoring and control of the pressure on the die side of the superplastic blank.
Claims17
An apparatus for forming articles from predominantly superplastic materials, which apparatus comprises:
- (1) a containment vessel having a container portion and a cover portion that between them form an enclosed cavity, the container portion and the cover portion being releasable to open the cavity;
- (2) means for clamping a sheet or blank of predominantly superplastic material across the cavity between the container portion and the cover portion;
- (3) a die that is removably located in the cavity of the container portion and that has an interior, an exterior and a bore extending between the interior and the exterior,
- (4) a space between the exterior of the die and the cavity wall, whic space is in fluid communication via the bore with the interior of the die,
- (5) ducts for feeding gas into the cavity on respective sides of the blank and for exhausting gas from the cavity on respective sides of the blank for establishing a pressure differential across the blank between a first side of the blank adjacent to the container portion and a second side adjacent to the cover protion, the arrangement being such that the pressure on both sides of the blank during the forming operation is greater than atmospheric pressure but the pressure on the second side is greater than that on the first side
- (6) means to heat the blank to a temperature at which superplastic forming can take place.
A method of forming an article from predominantly superplastic materials, which method comprises:
- (a) opening a containment vessel having a container portion and a cover portion that between them form an enclosed cavity,
- (b) placing into the container portion a die having an interior, an exterior and a bore extending between the said interior and the said exterior, the die being so dimensioned that there is a space between the exterior of the die and the cavity wall, which space is in fluid communication via the bore with the interior of the die,
- (c) clamping a blank of predominantly superplastic material across the cavity between the container portion and the cover portion,
- (d) heating the blank to a temperature at which the material of the blank exhibits superplastic properties, and establishing a pressure differential across the blank between a first side of the blank adjacent to the said container portion and a second side adjacent to the cover portion such that there is a positive pressure on both sides of the blank to avoid cavitation in the material but the pressure on the second side is greater than that on the first side, thereby urging the blank material into the die,
- (e) returning the pressure within the vessel to atmospheric pressure, and
- (f) opening the containment vessel, separating the formed article from the die and removing the article from the containment vessel.
Dependencies are inferred from the claim text.