Patent ID: 6997025

Claim:
A super-plastic forming tool for forming a heated sheet of metal having a first rate of thermal expansion by applying gas pressure to the sheet in a die having a second rate of thermal expansion that is less than the first rate, comprising: a first die having a peripheral portion that engages the aluminum alloy sheet; a second die having a peripheral portion that mates with the peripheral portion of the first die, the second die having a forming surface against which the aluminum alloy sheet is pressed; and a sealing bead formed on the peripheral portion of the first die; a peak formed on the sealing bead that is defined as the portion of the sealing bead that extends away from the peripheral portion of the first die to the greatest extent; an inner section of the sealing bead being defined as the portion of the sealing bead that is inboard of the peak; an outer section of the sealing bead being defined as the portion of the sealing bead that is outboard of the peak, the outer section is wider than the inner section as measured from the peak; and wherein the heated sheet of metal shrinks more rapidly as it cools than the first die to thereby facilitate separating the sheet of metal from the first die.