A SINGLE CONE BIT WITH OFFSET AXIS AND COMPOSITE CONES

摘要

This invention relates to a single cone bit with offset axis and compositecones for oil and gas drilling, mining and other subterranean drillingoperations.The bit consists of a head body and a cone. The cone section has a shape ofcomposite cones. The outer circumference of the cone is composed of fromback face of the cone to top of the cone an extended gage surface, an outercone surface and a main cone surface. A plurality of cutting elements ismounted onto each cone surface. A head journal at lower end of the head bodyis for rotatablely connection with the cone. Between the axis of head journaland the axis of the bit, there is an offset value d along rotating directionof thecone. A gage pad is arranged on head body at a location opposite to the offsetdirection of the head journal. The gage pad is fitted with inserts orhardfacedwith wear resistant alloy to prevent bit from whirling and prevent head bodyfrom being worn out and to ensure gage protection. Junk slots are machinedalong the side of head body and jet ports are arranged at lower bevel of thehead body to guarantee cuttings removal and effective cleaning results. Thisinvention improves the bit's ability to break rocks through impact forspecificuse in hard formations. The bit performance is obviously improved and overalldrilling cost reduced.