Importance

Loading Importance Indicators...

Abstract

A modular drill bit mounts legs within recesses in a body which are parallel to the central axis of the body using threaded studs with tapered outer portions, in conjuction with an attached pin having recesses therein receiving the upper ends of the legs. The lower ends of the legs terminate in spindles of open face configuration rotatably receiving cones thereon for rotation via a arrangement of bushings, roller bearings and thrust bearings, and a plurality of seals which slide and therefore rotate relative to both the leg spindle and the cone with the help of pressure compensating apparatus. A bushing disposed in the cone-leg spindle interface has oil-lubricated rubber rods disposed in apertures therein to prevent lock-up on an adjacent bearing surface. The cone is held on the leg spindle by a lock nut forming one end of a race for receiving rollers of a roller bearing, in conjunction with a ring-nut secured to an extended portion of the cone protecting the leg from wear and damage. The cone-leg spindle interface is lubricated by oil containing Teflon and molybdenum and which is pumped by a main thrust bearing for recirculation through radiator apparatus in the side of the leg. Such apparatus cools the oil in response to mud sprayed by an asymmetrical arrangement of adjustable ceramic nozzles mounted in a bottom surface of the body. Each cone is provided with cutting teeth which are inclined in the direction of cone rotation and which cover the cone surface in a manner which provides scraping of substantially the entire bottom surface of the hole being drilled and in a manner providing efficient scraping and crushing action. The cutting teeth are mounted in holes in the cone and then brazed in place, as are a plurality of ceramic buttons mounted within the extended portion of the cone to protect such portion and to provide backup gauging for a row of large cutting teeth mounted on an outer rim of the cone and having the cutting edges thereof inclined in alternating fashion.

Loading the Abstract Image...

First Claim