Apparatus for superplastic forming of large cylindrical structures

An apparatus for superplastic forming of large generally cylindrical structures, comprising:

• a generally cylindrical ceramic die having a radially inwardly facing surface defining the contour of a structure to be formed from a cylindrically rolled sheet positioned radially inwardly therefrom, the sheet being made of a metal selected from the group consisting of Titanium and Titanium alloy;
• generally cylindrical jacket means surrounding the ceramic die for reinforcing the same against radially outwardly directed loading forces;
• first radiant heating means positioned radially inwardly of the rolled metal sheet for heating a medial portion thereof to a temperature of between approximately at least 1600.degree.-1700.degree. F. at which it achieves a superplastic condition;
• an upper horizontal generally cylindrical metal support member having a radially outwardly facing surface for expanding and contacting an upper portion of the rolled metal sheet so that it contacts the radially inwardly facing surface of the ceramic die;
• an upper generally cylindrical metal seal member adjacent the upper horizontal support member and having a radially outwardly facing surface for expanding and contacting the upper portion of the rolled metal sheet so that it contacts the radially inwardly facing surface of the ceramic die;
• a lower horizontal generally cylindrical metal support member having a radially outwardly facing surface for expanding and contacting a lower portion of the rolled metal sheet so that it contacts the radially inwardly facing surface of the ceramic die;
• a lower generally cylindrical metal seal member adjacent the lower horizontal support member and having a radially outwardly facing surface for expanding and contacting the lower portion of the rolled metal sheet so that it contacts the radially inwardly facing surface of the ceramic die;
• a vertically extending generally cylindrical metal support positioned radially inwardly of, and connecting, the upper and lower horizontal support members;
• a round cross-section upper seal ring made of Copper positioned between the upper horizontal support member, the upper seal member and an upper radially inwardly facing surface of the rolled metal sheet;
• a round cross-section lower seal ring made of Copper positioned between the lower horizontal support member, the lower seal member and a lower radially inwardly facing surface of the rolled metal sheet;
• the upper horizontal support member and the upper seal member having a pair of inclined opposing surfaces, at least one of which terminates adjacent the rolled metal sheet with a shoulder for receiving the upper seal ring;
• the lower horizontal support member and the lower seal member having a pair of inclined opposing surfaces, at least one of which terminates adjacent the rolled metal sheet with a shoulder for receiving the lower seal ring;
• second radiant heating means for heating the upper and lower seal rings so that they soften, including a first pair of ceramic heater support rings on opposite sides of the upper horizontal support member and a second pair of ceramic heater support rings on opposite sides of the lower horizontal support member;
• the die, support members, seal members and radiant heating means being segmented along radial lines intersecting a central axis of the apparatus;
• water filled heat exchanger means adjacent the jacket means for preventing excessive heat build-up;
• and
• means for introducing a pressurized gas to force the medial portion of the rolled metal sheet radially outwardly against the ceramic die when the seal rings are softened to
• provide substantially gas impervious seals and the medial portion of the rolled metal sheet has been heated to a superplastic condition.