Abstract: A roller cone bit may be used as a rotating drag bit by treating the roller cones as carriers for a plurality of distinguishable types of drag cutters. The roller cones are each coupled to a mechanism which selectively allows rotation of the roller cones. The roller cones are otherwise fixed and as the bit is rotated, the drag cutters are brought into engagement with the rock. However, where the roller cones are selectively allowed to rotate, rotation of the drag bit rotates the roller cones to bring a second set of drag cutters into a configuration for cutting the rock formation. A mechanism then selectively locks the roller cones to prevent further rotation, keeping the second set of drag cutters fixed in place. By selectively permitting and preventing rotation of the roller cones, a plurality of sets of drag cutters can be brought into a configuration for cutting the rock.

Abstract: A rotary drill bit, for use in subsurface formations, comprises a bit body, a passageway for drilling fluid within the body, communicating with nozzles in the external surface of the body, preform cutting elements mounted on the body for cutting or abrading the formation, and a number of elongate fences upstanding from the external surface of the body to control the flow of fluid from the nozzles and past cutting elements. Each fence is resiliently deformable, for example being in the form of a brush having metal bristles, so that, in use, the free elongate edge of the fence is urged resiliently into contact with the surface of the formation being cut or abraded by the cutting elements. Since each fence is resiliently deformable it will at all times firmly engage the formation to provide an effective seal, regardless of variations in depth of cut of the cutting elements.

Abstract: A drill bit comprises a bit body having an operating end face. A plurality of self-sharpening cutters are mounted in the bit body and extend through the operating end face. The cutters have cutting faces adapted to engage an earth formation and cut the earth formation to a desired three-dimensional profile. The cutting faces define surfaces have back rake angles which decrease with distance from the profile. The individual cutting faces may be inwardly concave in a plane parallel to the intended direction of motion of the cutter in use. Each of the cutting members has a stud portion disposed in a respective recess in the bit body and defining the inner end of the cutting member, the cutting face being generally adjacent the outer end and having an outer cutting edge. The centerline of the stud portion is rearwardly inclined, from the outer end to the inner end, with respect to the direction of movement in use, taken at the midpoint of the cutting edge, at a first angle from 80.degree. to 30.degree. inclusive.

Abstract: A drill bit comprises a bit body having an operating end face. A plurality of self-sharpening cutters are mounted in the bit body and extend through the operating end face. The cutters have cutting faces adapted to engage an earth formation and cut the earth formation to a desired three-dimensional profile. The cutting faces define surfaces having back rake angles which decrease with distance from the profile. The individual cutting faces may be inwardly concave in a plane parallel to the intended direction of motion of the cutter in use.

Abstract: A self-sharpening rotary drag bit assembly comprises:(a) a carrier body adapted to be rotated about a first axis, and having a drilling end,(b) cutters carried by the body to be exposed for cutting at the drilling end of the body, the cutters having thereon layers of hard materials defining cutting edges to engage and cut the drilled formation as the body rotates, the cutters also including reinforcement material supporting said layers to resist deflection thereof under cutting loads,(c) said body and said reinforcement material being characterized as abradable by the formation as the bit drilling end rotates in engagement with the formation.

Abstract: A drill bit for drilling a subterranean bore hole which includes a housing having a cap plate adapted for connection to a drill pipe and a base block axially aligned with and spaced from the cap plate by guide members. A plurality of elongated drill rod impact members are carried by a drill rod holder plate disposed between the cap plate and base block for movement longitudinally of the housing. The free ends of the drill rods extend through guide bores in the base block to define exposed working ends for chipping and crushing the formation upon rotation of the drill bit and the introduction of drilling fluid into the housing in a manner to effect a hammer-like action of the drill rods and progressively move them longitudinally outwardly from the base block as they undergo wear.

Abstract: A continuous chain bit for hard rock drilling is capable of downhole cycling. A drill head assembly moves axially relative to a support body while the chain on the head assembly is held in position so that the bodily movement of the chain cycles the chain to present new composite links for drilling. A pair of spring fingers on opposite sides of the chain hold the chain against movement. The chain is held in tension by a spring-biased tensioning bar. A head at the working end of the chain supports the working links. The chain is centered by a reversing pawl and piston actuated by the pressure of the drilling mud. Detent pins lock the head assembly with respect to the support body and are also operated by the drilling mud pressure. A restricted nozzle with a divergent outlet sprays drilling mud into the cavity to remove debris.

Abstract: A method of fabricating a rock bit insert which has improved wear characteristics is disclosed. Selected surfaces of the insert are implanted with a harder grade of tungsten carbide and sintered thereto. The special insert then would find application in the gage row of, for example, a roller cone rock bit.

Abstract: A drill bit including a support member and a plurality of concentrically positioned, hollow, cylindrical cutting members connected to the support member is disclosed. Each of the cutting members includes a beveled edge obliquely extending between the inner and outer surfaces thereof. The beveled edges are aligned so that a tapered cutting surface is defined.

Abstract: There is disclosed an ablatible drill comprising a soft or frangible matrix having embedded therein a multiplicity of hard inclusions which act as cutting teeth. During drilling, the matrix gradually wears away so that worn inclusions are circulated out of the hole and fresh inclusions are exposed as new cutting teeth. A plurality of joints of the ablatible drill are interconnected on the bottom of a drill string. The comminuted material of each joint of the ablatible drill provides a characteristic distinguishable from the comminuted material of adjacent joints so that in examination of the circulated returns provides an indication of which joint is then being drilled.

Abstract: A drill having plural forwardly projecting circumferentially spaced cutting bits includes a hydraulic motor operated at full drilling fluid pressure to drive the cutting bits in unison through a first one-way clutch in a drilling mode. A centrifugal device responding to higher speed rotation of the drill operates a reversing valve connected with the hydraulic motor to reverse it at required times to incrementally advance the cutting bits of the drill in unison to compensate for wear and present a new sharp cutting face on each bit for continued drilling. The reversal of rotation of the bits is transmitted from the hydraulic motor through a second one-way clutch of the single revolution type which drives a pinion common to and in mesh with drive gears individual to the several cutting bits and matching the shapes of their flutes and being axially slidable relative thereto.

Abstract: A diamond drill bit for drilling bore holes in earth formations having a body connectible to a drilling string, and provided with a matrix portion of hard metals in which diamonds are surface set at the outer gage portion and adjacent to the bit axis, the hard metal matrix having preformed grooves in which preformed diamond impregnated segments are inserted, which are a mixture of diamonds and hard metals, and secured to the matrix portion by brazing material. During bit rotation in the bore hole, the segments cut the major portion of the hole, the diamonds being dispersed throughout the mass of each segment for selective release from the segment as the diamonds become damaged and lost, thereby exposing new diamonds in the segment at a controlled rate, and thereby producing continual resharpening of the segments. As a result, the drilling rate of the bit is increased, as well as the length of hole drilled.

Abstract: An improved rotary drill bit comprised of two or more elongated generally cylindrical drill members the lower ends of which form a cutting face. Each of the drill members includes a plurality of vertically spaced rows of diamond-shaped openings disposed, or formed, in the sides, or wall, thereof, the openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as the lower ends of the drill member wear away, cutting edges are continuously formed thereon by the diamond-shaped openings.

Abstract: An improved rotary drill bit comprised of two or more elongated generally cylindrical drill members, the lower ends of which form a cutting face. A plurality of vertically spaced rows of rotatable cutting members are positioned around and between the drill members and are journaled thereto whereby as the lowermost row of the rotatable cutting members and the lower ends of the drill members wear away, the next adjacent row of cutting members is exposed.

Abstract: A rotary abrasive drilling bit disclosed herein is of a construction wherein teeth are equipped on the fore part of a bit body attached to a rotary drill pipe, each of said teeth is composed of a plurality of chips which are made of cemented tungstencarbide and the matrix thereof which is soft and inferior in abrasion resistance relative to said cutting elements or chips, each chip is shaped like a thin stick and extends along the cutting direction of said bit body, the matrix surrounds said chips, and in the matrix of each tooth the chips are orderly arranged to leave a desired interspace along the direction of radius as well as the direction of circumference of the bit body.

Abstract: A diamond drill coring bit having an annular crown and inner and outer concentric side surfaces. The crown is formed from a number of radially extending composite segments spaced apart circumferentially by a circumferential spacer material, all integrally bonded together. Each composite segment consists of a number of diamond impregnated segments spaced radially from each other by a radial spacer material. The diamond impregnated segments have greater abrasion resistance than that of the radial spacer material such that the radial spacer material will wear at a controlled rate greater than that of the diamond impregnated segments. The radial spacer material has greater abrasion resistance than that of the circumferential spacer material such that the circumferential spacer material will wear at a controlled rate greater than that of the radial spacer material but not so great as to prematurely expose the composite segments.

Abstract: An abrasive member providing a working surface characterized by having a multiplicity of upstanding angularly extending ridges. Particles of an abrasive material, such as diamond, are affixed to the ridges in a manner so that as the tops of the ridges wear down, fresh particles of the abrasive material will become reembedded therein, thereby continually presenting a fresh cutting surface.