US Patent 7320375 Split cone bit

A roller cone drill bit and a method for designing thereof. The roller cone drill bit includes a bit body configured to be coupled to a drill string and a journal depending from the bit body. A split roller cone is rotatably attached to the journal. The split roller cone includes an upper section and a lower section. The upper section has a plurality of cutting elements disposed at selected positions thereon. The lower section has a plurality of cutting elements disposed at selected positions thereon. The lower section is able to rotate independently of the upper section.