Abstract: A mechanical seal for rotary rock bits with a uniquely formed hydrodynamic wave geometry on the sealing faces. The sealing faces are first manufactured flat and smooth, then upon assembly are elastically deformed into a hydrodynamic geometry by an energizing system. After a smooth flat sealing surface is formed, the mechanical seal face elastically deforms into a hydrodynamic wave geometry. The typical deformation has a magnitude greater than about three helium light bands more than the original surface. The region of the sealing surface at the outer periphery of the seal does not have a wave geometry. Rather the portion of the seal face at the periphery is flat and parallel to its mating seal ring to exclude abrasives and eliminate lubricant leakage.

Abstract: A rolling cutter drill bit has at least one roller cutter mounted on a cantilevered bearing shaft with a sealed bearing and lubrication system, lubricant pressure balancing means, lubricant pressure relief means, and a volume compensating rigid face seal assembly axially movable through an operating range. The face seal assembly comprises two cooperating face seal rings, one ring mounted on the bearing shaft and the other ring mounted in the cutter; a first energizer for the seal ring mounted on the bearing shaft, having a stiffness K1; and a second energizer for the seal ring mounted in the cutter, having a stiffness K2. In order to minimize the variation in the sealing face force as the assembly moves through its operating range, the stiffness K2 is less than half, and preferably less than 0.2, of the stiffness K1.

Abstract: A moth type rolling cutter drill bit has a plurality of rolling cutters mounted on legs, each rolling cutter having a back face portion and a gage face portion, and a high velocity fluid nozzle which directs a stream of high velocity fluid toward the cutter. Each cutter has a row of gage teeth to cut the gage of the borehole, and at least one of the cutters has a plurality of flow channels spaced apart around its gage face portion to provide fluid communication from the back face of the cutter and between and around pairs of adjacent gage teeth. Each flow channel is inclined at an angle to a radius of the cutter so as to be oriented towards the stream of fluid from the high velocity nozzle as the teeth adjacent to the flow channel engage the formation being drilled.

Abstract: A method of manufacturing a rolling cutter drill bit comprising a bit body which carries cutter assemblies each of which includes a cutter journal on the bit body, a cutter rotatably mounted on the journal, and a threaded retention ring screwed onto the cutter to retain the cutter on the journal while permitting a limited degree of axial displacement of the cutter relative to the journal. The method comprises the steps of predetermining a desired magnitude of maximum permitted axial displacement between the cutter and the journal, and then employing components for the cutter assembly which are so dimensioned as to provide, when assembled to form the cutter assembly, a maximum permitted axial displacement which is not greater than the predetermined magnitude. The appropriately dimensioned components may be specifically manufactured to the required size, or may be selected from a stock of components of differing sizes.

Abstract: A rotary drill bit (10) has fluid discharge nozzles (36A, 36B, 36C) positioned between adjacent pairs of roller cutters (20A, 20B, 20C). A fluid discharge nozzle (36A) provides a stream of drilling fluid (44) directed toward an adjacent roller cutter (20A) and slanted toward the bore hole side wall away from a radial direction at a slant impact angle B for first impacting the side wall (34), and then sweeping in a high velocity stream along the corner surface (33) and inwardly across the bore hole bottom (32) at cutting element engagement locations (39).

Abstract: A rotary drill bit (10) has fluid discharge nozzles (36A, 36B, 36C) positioned between adjacent pairs of roller cutters (20A, 20B, 20C). A fluid discharge nozzle (36A) provides a stream of drilling fluid (44) toward an adjacent roller cutter (20A) inclined radially outwardly toward the side wall (34) of the bore hole (30) and slanted toward the roller cutter (20A) for first striking the side wall (34), and then sweeping inwardly across the bore hole bottom (32) in a flat high velocity stream tangential to bit rotation and beneath the cutting elements (26) during cutting engagement of the gage row (28D) with the formation.

Abstract: A rotary drill bit (10) having a roller cutter (28) retained on a journal (24) by an externally threaded retainer ring (52) mounted within an annular groove (48) in the journal (24). The radii (R1, R2) formed at the inner and outer corners of the groove (48) are designed by suitable formulas to provide adequate strength for the journal (24) including the flange (50) adjacent the groove (48).

Abstract: A roller cutter (28) of a drill bit (10) is retained on a journal (24) for rotation by a retainer ring (82) having external screw threads (88) which are threaded onto mating screw threads (108) on the roller cutter (28) for rotation therewith. The retainer ring (82) is mounted within a semicircular groove (68) on the journal (24) and has an inner periphery formed of a smooth arcuate surface contacting the annular groove at a position spaced at least 10.degree. from the entrance opening of the groove thereby to reduce bending stresses exerted against the root (74) of the groove (68).