Importance

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Abstract

An improved method of superplastic forming comprises the steps of selecting a relatively larger driver sheet and a relatively smaller part blank, both being made of Titanium, Titanium alloy or other metal capable of exhibiting superplasticity. A ceramic die is placed on a bottom wall of an upwardly opening ceramic forming chamber having sidewalls with upper edges. The ceramic chamber has an outer supporting steel jacket. The part blank is positioned over the die. The driver sheet is positioned over the part blank so that the peripheral edges of the driver sheet rest on the upper edges of the sidewalls of the forming chamber. A cover is provided for closing the chamber. It has a peripheral seal extending from an underside thereof. The cover and the chamber are clamped together in order to impinge the seal into a periphery of the driver sheet. The driver sheet and part blank are then heated to a predetermined temperature at which they exhibit superplasticity. Next a pressurized inert gas is introduced into an interior formed by the closed cover and chamber and thereafter released so that the driver sheet presses and forms the part blank around the die. The peripheral edges of the part blank are free to draw in during the forming to thereby avoid any undesired necking or thinning. The cover is lifted from the chamber and the formed driver sheet and part blank are removed.

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First Claim