| 主权项 |
1. A drill bit for drilling a subterranean formation, comprising:
a bit body having a shank secured thereto for affixing the bit to a drill string; and a plurality of cutting elements secured to the bit body, at least one of the cutting elements having a longitudinal axis and comprising:
a substantially planar table of superabrasive material substantially facing a direction of intended bit rotation, a plane of the table extending perpendicular to the longitudinal axis of the cutting element, the plane of the table oriented at a backrake angle with respect to an axis of the drill bit, the superabrasive table having a cutting face, a side surface and a peripheral edge therebetween, the peripheral edge being defined at least in part by:at least one chamfer between the side surface and the cutting face oriented at an acute angle to the side surface;an arcuate surface extending directly between an outermost boundary of the cutting face and an innermost boundary of a chamfer of the at least one chamfer; anda sharp, angular transition between an outermost boundary of a chamfer of the at least one chamfer and the side surface; wherein the acute angle of a radially outermost chamfer of the at least one chamfer with respect to the side surface of the table is approximately the same as or slightly more than the backrake angle of the plane of the table with respect to the axis of the drill bit; and wherein an included angle between the cutting face and the at least one chamfer is greater than about 135°. |
