Patent ID: 8567530
Filing Date: 2013-10-29
Classification: E21B

Abstract:
1. An apparatus comprising: a cutter bit which has front and rear ends defining therebetween an axial direction and which rotates during operation about an axis which extends in the axial direction; the cutter bit adapted to rotate within an underground casing having a cylindrical inner surface of a first inner diameter; a base of the cutter bit; a plurality of rock cutters configured for cutting rock when the cutter bit is rotated about the axis; a plurality of movable cutter mounts each of which is mounted on the base, carries one of the cutters and is non-pivotally movable radially inwardly and outwardly between a collapsed position in which the respective cutter is entirely radially inward of the first inner diameter and an expanded position in which the respective cutter is at least partially radially outward of the first inner diameter whereby the cutter bit is adapted to be withdrawn through the casing in the collapsed position and to cut rock forward of the casing in the expanded position; and a drive section of the cutter bit adapted to be rotationally driven by an auger having a helical flight; and wherein the movable cutter mounts move radially in response to rotation of the drive section about the axis relative to the base.