US Patent 7661473 Expansion enhancement device

Nested articulated split rings move relatively to each other to enlarge their outer dimension for a grip on a surrounding tubular or the wellbore. The rings can be articulated to enlarge their outside dimension with relative movement that can be initiated by dimensional expansion from within the tubular or manipulation of the tubular that creates the desired relative movement. The relative movement can be locked in after it is made to secure the grip. Different shape profiles that magnify the radial outer dimension in excess of the percentage dimensional change in the underlying tubular are contemplated.