DRILL BIT CUTTER AND METHOD FOR REDUCING PRESSURE LOADING OF CUTTINGS

摘要

A drag-type drill bit for boring an earth formation having a plurality of cutting elements (20) formed thereon. Each cutting element includes a cutting surface (30) having a cutting edge (34) formed thereon. During boring, the cutting edge is embedded into an earth formation (36) so that the formation is received against a portion of the cutting surface. As the cutting surface advances against the formation, a chip forms. The chip has a first surface (62) directed generally toward the cutting surface and a second surface (64) directed generally in the direction of cutting element travel. A number of different embodiments are disclosed which include means formed on and in the cutting surface for communicating drilling fluid pressure via slots or discontinuities (42) to a location on the cutting surface relatively close to the cutting edge. Drilling fluid pressure across the chip is thus equalized thereby preventing the chip from being urged against the cutting surface due to the difference between the formation pressure and the drilling fluid pressure.