Importance

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Abstract

A method for preparing rings having an integral stiffening geometric pattern on its outer surface is disclosed. The method employs a variation of the drum rolling process, but it incorporates unique tooling for providing the pattern, preferably comprising a plurality of segments which fit together to define a ring, the inner surface of which presents the desired pattern toward the center of the ring. A unique drum arrangement includes inner and outer components for locking the segments in place and for providing the structural integrity required for the final drum rolling operation. A cylinder, for example an aluminum or aluminum alloy cylinder, is placed in the drum, the cylinder being preformed and presized to fit concentrically within the segment defining ring. Following heating of the assembly to forming temperature, the cylinder is radially expanded using a sizing tool, and the assembly is then placed over a mandrel in preparation for drum rolling. In the illustrated embodiment, an isogrid pattern of recesses is formed in the segments, so that upon completion of drum rolling and disassembly of the drum and segments, a raised, integral isogrid stiffening pattern is provided on the outer ring cylinder surface.

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First Claim