ROLLER CONE DRILL BIT ASSEMBLY WITH VARYING RADIUS BEARING SURFACES

摘要

A roller cone drill bit assembly with a bearing shaft having an outer bearing surface and defining a rotational axis. The outer bearing surface includes a necked portion having a varying radius with respect to the rotational axis. A roller cone is coupled about the bearing shaft and includes an outer cutting structure and an inner bearing surface. The inner bearing surface includes a necked portion proximate to and closely conforming to the necked portion of the outer bearing surface.