A hybrid rotary cone drill bit includes a plurality of legs. A bearing shaft extends from each leg, and a rotary cone is rotationally coupled to each bearing shaft. At least one rotary cone includes a nose row of cutting structures, an inner row of cutting structures, and a gage row of cutting structures. The nose row and the inner row of cutting structures are formed of milled teeth. The gage row of cutting structures is formed of cutter inserts.

A hybrid rotary cone drill bit includes a plurality of legs. A bearing shaft extends from each leg, and a rotary cone is rotationally coupled to each bearing shaft. At least one rotary cone includes a nose row of cutting structures, an inner row of cutting structures, and a gage row of cutting structures. The nose row and the inner row of cutting structures are formed of milled teeth. The gage row of cutting structures is formed of cutter inserts.

An earth-boring drill bit is described, the bit having a bit body having a central longitudinal axis that defines an axial center of the bit body and configured at its upper extent for connection into a drill string; at least one primary fixed blade extending downwardly from the bit body and inwardly toward, but not proximate to, the central axis of the drill bit; at least one secondary fixed blade extending radially outward from proximate the central axis of the drill bit; a plurality of fixed cutting elements secured to the primary and secondary fixed blades; at least one bit leg secured to the bit body; and a rolling cutter mounted for rotation on the bit leg; wherein the fixed cutting elements on at least one fixed blade extend from a center of the bit outward toward a gage region of the bit but do not include a gage cutting region, and wherein at least one roller-cone cutter portion extends from substantially the drill bit's gage region inwardly toward the center of the bit, an apex of the roller-cone cutter being proximate to the terminal end of the at least one secondary fixed blade, but does not extend to the center of the bit.

An earth-boring drill bit is described, the bit having a bit body having a central longitudinal axis that defines an axial center of the bit body and configured at its upper extent for connection into a drill string; at least one primary fixed blade extending downwardly from the bit body and inwardly toward, but not proximate to, the central axis of the drill bit; at least one secondary fixed blade extending radially outward from proximate the central axis of the drill bit; a plurality of fixed cutting elements secured to the primary and secondary fixed blades; at least one bit leg secured to the bit body; and a rolling cutter mounted for rotation on the bit leg; wherein the fixed cutting elements on at least one fixed blade extend from a center of the bit outward toward a gage region of the bit but do not include a gage cutting region, and wherein at least one roller-cone cutter portion extends from substantially the drill bit's gage region inwardly toward the center of the bit, an apex of the roller-cone cutter being proximate to the terminal end of the at least one secondary fixed blade, but does not extend to the center of the bit.

A cutting element may include a substrate including a plurality of metal carbide particles and a first metal binder having a first metal binder content; an outer layer of polycrystalline diamond material at an end of the cutting element, the polycrystalline diamond material including a plurality of interconnected diamond particles; and a plurality of interstitial regions disposed among the interconnected diamond particles, the plurality of interstitial regions containing a second metal binder having a second metal binder content. The cutting element also includes at least one transition zone between the substrate and the outer layer, the at least one transition zone including a plurality of refractory metal carbide particles and a third metal binder having a third metal binder content, the third metal binder content being less than the first metal binder content and the second metal binder content.

A cutting element may include a substrate including a plurality of metal carbide particles and a first metal binder having a first metal binder content; an outer layer of polycrystalline diamond material at an end of the cutting element, the polycrystalline diamond material including a plurality of interconnected diamond particles; and a plurality of interstitial regions disposed among the interconnected diamond particles, the plurality of interstitial regions containing a second metal binder having a second metal binder content. The cutting element also includes at least one transition zone between the substrate and the outer layer, the at least one transition zone including a plurality of refractory metal carbide particles and a third metal binder having a third metal binder content, the third metal binder content being less than the first metal binder content and the second metal binder content.

A cutting element (30) includes a substrate (40); and a body of superhard polycrystalline material (34) bonded to the substrate (40) along an interface, the body of superhard polycrystalline material having a peripheral side edge (42). The body of superhard polycrystalline material has a cutting surface (34); a plurality of spaced apart cutting edges (36) extending to the cutting surface (34) through respective chamfer portions (38), the cutting edges being spaced around the peripheral side edge; a plurality of recesses/regions (48) extending from the cutting surface (34) towards the substrate, adjacent cutting edges (36) being spaced apart by a respective one of said recesses/regions (48); and a protrusion or recessed region extending from the cutting surface about a central longitudinal axis of the cutting element. A method of making such a cutting element is also disclosed.

A method of manufacturing a roller cone includes machining a cone blank and thereby defining one or more land surfaces and one or more insert grooves on the cone blank, surface hardening the cone blank, and milling a plurality of recesses into at least one of the one or more land surfaces. The method further includes subjecting the cone blank to a quenching process, forming an insert hole at each recess, and inserting an insert into each insert hole.

A method of manufacturing a roller cone includes machining a cone blank and thereby defining one or more land surfaces and one or more insert grooves on the cone blank, surface hardening the cone blank, and milling a plurality of recesses into at least one of the one or more land surfaces. The method further includes subjecting the cone blank to a quenching process, forming an insert hole at each recess, and inserting an insert into each insert hole.

A cutting element assembly includes a sleeve, a lining extending a distance axially from an end of the sleeve, and an inner cutter. The inner cutter has a cutting end, wherein the cutting end extends a depth from a cutting face, a side surface, and a body, wherein the body is at least partially disposed within the sleeve, and wherein the side surface of the cutting end interfaces with an interfacing surface of the lining.