A drill bit that includes a bit body, at least one roller cone attached to the bit body and able to rotate with respect to the bit body, a plurality of cutting elements disposed on the at least one roller cone, and a barrel axis is disclosed. At least one of the plurality of cutting elements includes a first area defining a secondary wear surface, wherein the first area is formed as a convex surface on the trailing edge, a second area proximate the first area defining a main wear surface, wherein the second area is formed as a convex curved surface having a radius of curvature substantially equal to a radius of a borehole, and a third area defining a spherical cutting surface. Further, at least one of the plurality of cutting elements includes a non-spherical transition zone disposed between the third area and the first and second areas, wherein the barrel axis intersects the transition zone.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application No. 60/423,561 filed on Nov. 4, 2002. That application is incorporated by reference in its entirety.
A drill bit having a bit body, at least one roller cone attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on the at least one roller cone is disclosed. At least one of the plurality of cutting elements includes a first area defining a trailing edge, a second area proximate the first area defining a main wear surface, and a third area proximate the second area and defining a leading edge relief zone. Further, an insert for a drill bit having a contact portion adapted to contact an earth formation, the contact portion including a first area defining a relieved trailing edge, a second area defining a main wear surface, and a third area proximate the second area and defining a leading edge relief zone.
