Earth drilling knobby bit

Abstract

A partially solid head bit having a flow passage therethrough located at approximately the center of the bit is shown. The bit is designed for use in conjunction with a hammer action drilling apparatus. The flow passage extends through a shank of the bit to the bottom thereof. Surrounding the shank is a substantially hemispherical spiraled burr having an opening therethrough. The burr pushes against a shoulder of the shank during drilling. The mating surfaces of the shank and burr are lubricated by a suitable oil reservoir. On spirals of the burr and on the lower end of the shank are mounted hardened inserts for impacting against and breaking up the formation through which the bit may drill. The bottom of the shank may be even with, extend through, or be recessed with respect to the lower edge of the burr. The shank is angled a few degrees off the centerline of the drilling string to cause a wobbling action upon rotating the drill bit.

Dependencies are inferred from the claim text.