| 摘要 |
A drill bit having a bit body, at least one blade extending radially from the bit body, a plurality of blade cutting elements disposed on each blade, at least one journal extending downwardly and radially outward from a longitudinal axis of the drill bit, a roller cone or roller disc mounted rotatably to each journal, and a plurality of cutting elements disposed on each roller cone or roller disc, and methods for making the drill bit are disclosed. |
