Patent ID: 7410015

Claim:
An expandable drill bit comprising: a body for mounting on a support string, a plurality of drill arms coupled to the body and extending along a central longitudinal axis, at least one drill arm supporting cutting elements, and the plurality of drill arms being pivotable between a retracted configuration and an expanded configuration, the retracted configuration defining an expandable drill bit having a first cutting diameter, the expanded configuration defining an expandable drill bit having a second cutting diameter greater than the first cutting diameter, wherein the drill arms are driven from the retracted configuration into the expanded configuration when the expandable drill bit is rotated at a speed of rotation at least equal to a determined expanding speed of rotations, and wherein: the drill arms comprise at least two main drill arms, and at least two intermediate drill arms, the main drill arms defining an end of a drill bit internal conduit coaxial to the central longitudinal axis, in the retracted configuration, each main drill arm contacts another main drill arm, and the intermediate drill arms are positioned within the end of the drill bit internal conduit, and in the expanded configuration, the main drill arms and the intermediate drill arms pivot laterally so that each intermediate drill arm fits between two main drill arms.