Patent ID: 7942217
Filing Date: 2011-05-17
Classification: E21B

Abstract:
1. A cutting apparatus for a drill head section, the cutting apparatus comprising: a front cutting rotor having a central hub defining a central cavity that extends completely through the central hub and is adapted to receive a drill shaft, the central cavity having flats adapted to engage corresponding flats of the drill shaft to allow torque to be transferred from the drill shaft to the front cutting rotor, the front cutting rotor also including a plurality of cutting bars having lengths, widths and depths, the depths extending in a front to back orientation along an axis of rotation of the front cutting rotor and the lengths projecting radially outwardly from the central hub, the lengths being longer than the depths, the lengths being longer than the widths, the widths being oriented perpendicular relative to the lengths and the depths, and the cutting bars including surfaces at which a plurality of cutting teeth are mounted; and a front retainer that mounts at a front side of the front cutting rotor for retaining the front cutting rotor on the drill shaft, the front retainer including a front cutting surface and also including a rear internally threaded opening into which a threaded end portion of the drill shaft is threaded.