Abstract: A drill bit has a bit body and at least one roller cone rotatably mounted on the bit body. The cone has a plurality of milled teeth at selected locations on the cone. At least one of the milled teeth has a substrate having a convex crest and a layer of hardfacing applied to the convex crest. The convex crest is adapted to produce at least one of a convex axial stress distribution, a substantially even axial stress distribution, and a substantially smooth axial stress distribution.

Abstract: Roller cone drilling wherein the bit optimization process equalizes the downforce (axial force) for the cones (as nearly as possible, subject to other design constrain). Bit performance is significantly enhanced by equalizing downforce.

Abstract: A rolling cone drill bit is provided that has gage inserts on the first row from the bit axis to cut to full gage diameter that have a cutting portion enhanced with a layer of super abrasive material. The gage cutting surface has a center axis that is canted to be more normal to the gage curve such that the its point of contact at gage is away from the thinner portion of the layer of super abrasive material.

Abstract: A rotary cone bit, having a functionally-engineered surface of this invention, comprises a bit body having at least one leg extending therefrom, and a cone that is rotatably disposed on the leg. The cone typically comprises a plurality of cutting elements that project outwardly therefrom. The cutting elements comprises a cermet material selected from the group consisting of refractory metal carbides, nitrides, borides, carbonitrides and mixtures thereof. A functionally-engineered material is disposed over a surface portion of at least one of the cutting elements to form a wear resistant surface thereon. The wear resistant surface has a hardness that is different than that of the underlying cutting element. The wear resistant surface is provided by forming a conformable material mixture by combining one or more powders selected from the group consisting of cermets, carbides, borides, nitrides, carbonitrides, refractory metals, Co, Fe, Ni, and combinations thereof, with an applying agent.

Abstract: A hardfacing material is applied to cutting elements formed on the surface of cutters of an earth-boring bit. The hardfacing material forms the outer surface of the teeth, and also substantially forms scrapers on the shell of each of the cutters. The adding of the hardfacing material to the outer surface of the teeth and the forming of the scrapers is accomplished through welding. The hardfacing material is machined from its “as-welded” state to have a smoother surface finish.

Abstract: A novel rolling cone rock bit includes a plurality of PDC or other cutters mounted to the leg of the drill bit and positioned to cut the troublesome corner of the bottomhole. The plurality of cutters may be the primary cutting component at gage diameter, or may be redundant to gage teeth on a rolling cutter that cut to gage diameter. Consequently, the occurrence of undergage drilling from the wear and failure of the gage row on a rolling cutter is lessened. Another inventive feature is the inclusion of a mud ramp that creates a large junk slot from the borehole bottom up the drill bit. The resulting pumping action of the drill bit ramp speeds up the removal of chips or drilling cuttings from the bottom of the borehole, reduces the level of hydrostatic pressure at the bottom of the borehole and minimizes the wearing effect of cone inserts regrinding damaging drill cuttings.

Abstract: Disclosed are a variety of arcuate-shaped inserts for drill bits, and in particular, for placement in rolling cone cutters of drill bits. The arcuate inserts include 360 degree or ring-shaped inserts, as well as inserts of smaller arcuate length. The arcuate inserts may include stress relieving discontinuities such that, upon assembly into the cone, the arcuate inserts fragment in a controlled and predicted manner into shorter arcuate lengths. The arcuate inserts are suitable for use in all surfaces of the rolling cone cutter, and in other locations in drill bits, and may have specialized cutting surfaces and material enhancements to enhance their cutting duty performance.

Abstract: An insert for a rock bit that includes tungsten carbide particles, and a cobalt binder disposed around the particles, wherein a grain size of the tungsten carbide particles and a content of the cobalt binder are selected to provide a fracture toughness of at least about 18 ksi (in)0.5, a wear number of at least about 2, and a hardness of 85 to 87 Ra is disclosed.

Abstract: A hardfacing composition for a drill bit is disclosed which includes a carbide phase made from about 80% to less than 100% by weight of a combination of sintered carbide pellets and crushed cast carbide and from more than 0% to about 20% by weight of carburized tungsten carbide. The composition includes a binder alloy. A roller cone drill bit includes a bit body and at least one roller cone rotatably mounted to the bit body. The at least one roller cone includes at least one cutting element. The cutting element has on its exterior surface a hardfacing. The hardfacing on the cutting element was formed with a hardfacing composition that includes a binder alloy and a carbide phase, which includes from about 80% to less than 100% by weight of a combination of sintered carbide pellets and crushed cast carbide, and from more than 0% to about 20% by weight of carburized tungsten carbide.

Abstract: A cutting insert for a gauge row of a percussion drill bit includes a generally cylindrical mounting portion extending along a central axis and a cutting head extending from the mounting portion. The cutting head has an exposed surface forming a non-symmetrical dome shape such that the working portion of the cutting head is enlarged with respect to a standard dome shape and a trailing portion of the cutting head is reduced with respect to a standard dome shape. The cutting head has an inner edge and an outer edge. The exposed surface is non-symmetrical along a central plane which bisects the working portion and the trailing portion. The exposed surface is symmetrical in a second plane perpendicular to the central plane such that the exposed surface forms an arc of constant radius from the inner edge to the outer edge in the second plane.

Abstract: A fracture and wear resistant rock bit is disclosed, which includes a bit body, and at least one roller cone disposed on the bit body adapted such that at least one row of cutting elements disposed on the at least one roller cone defines a gage row. At least one cutting element disposed on the gage row has a fracture toughness of at least 20 ksi (in)0.5 and a wear number of at least 1.5.

Abstract: Hardfacing is deposited on a PDC-equipped steel body rotary drag bit and forms substantially protruding structural elements, such as wear knots or chip breakers. Hardfacing may also be applied to features such as gage pads, wherein at least two different hardfacing compositions are utilized and specifically located in order to exploit the material characteristics of each type of hardfacing composition employed. The use of multiple hardfacing compositions may further be employed as a wear-resistant coating on various elements of the drill bit. The surfaces to which hardfacing is applied may include machined slots, cavities or grooves providing increased surface area for application of the hardfacing. Additionally, such surface features may serve to effect a desired residual stress state in the resultant hardfacing layer or other structure.

Abstract: An insert for a drill bit is disclosed which includes an exposed surface having a contact portion adapted to periodically contact earthen formation. The contact portion includes a polycrystalline diamond material having a hardness in the range of about 2000 HV to about 3000 HV. In some embodiments, the polycrystalline diamond material includes a composite having a first phase material including polycrystalline diamond and a second phase material selected from the group of oxide particulates metal carbides, and metallic particulates, nitrides, and mixtures of thereof.

Abstract: A rolling cone drill bit is provided that has gage inserts on the first row from the bit axis to cut to full gage diameter that have a cutting portion enhanced with a layer of super abrasive material. The gage cutting surface has a center axis that is canted to be more normal to the gage curve such that its point of contact at gage is away from the thinner portion of the layer of super abrasive material.

Abstract: A cutter element for a drill bit has a non-rectilinear crest. The cutter element has a base portion and an extending portion and the extending portion has either a zero draft or a negative draft with respect to the base portion. The non-positive draft allows more of the borehole bottom to be scraped using fewer cutter elements. The cutter elements having non-positive draft can be either tungsten carbide inserts or steel teeth.

Abstract: In one embodiment, a hardfacing composition for a drill bit, including a carbide phase including from about 50% to about 80% by weight of the hardfacing composition of a combination of 80 to 200 mesh macro-crystalline tungsten carbide and 80 to 200 mesh crushed cast carbide, the crushed cast carbide being about 5% to 50% of the total weight of the carbide phase, and a binder alloy comprising about 20% to about 50% by weight of the hardfacing composition is disclosed. A hardfacing composition for a drill bit, including a carbide phase composed of sintered tungsten carbide having a particle size from about 80 to 200 mesh that is about 50% to about 80% by weight of the hardfacing composition, and a binder alloy forming about 20% to about 50% by weight of the hardfacing composition.

Abstract: Rock bits comprising wear and fracture resistant surface of this invention include a steel bit body having at least one leg extending therefrom. A steel cone is rotatably disposed on the leg. The steel cone includes a plurality of steel cutting elements that each projecting outwardly a distance therefrom. At least a portion of the cone comprises a wear resistant surface formed from a wear resistant composite material. The wear resistant composite material is made by the process of combining powders selected from the group consisting of carbides, borides, nitrides, carbonitrides, refractory metals, cermets, Co, Fe, Ni, steel, and combinations thereof, to form a material mixture. The material mixture is applied onto a designated surface of the cone, in one form or another, when the cone is in a pre-existing rigid state. Depending on the particular application, the material mixture can be applied in as a slurry to the designated surface of the cone to form a coating thereon.

Abstract: A method for applying hardfacing to teeth on a drill bit is disclosed. The method includes applying the hardfacing to at least one of the teeth so as to have a thickness selected to correspond to a position about exterior surface of the tooth. In one embodiment, the hardfacing thickness is increased near the crest of the tooth, and is decreased near the root of the tooth on at least one flank of the tooth. In one embodiment, the thickness is selected by controlling the powder flow rate in a plasma transferred arc welding system. In another embodiment an angle subtended by flanks of the tooth is selected to provide increased strength to the tooth, and the hardfacing is applied to the tooth to cause exterior surfaces of the hardfacing corresponding to the flanks to subtend an angle selected to provide increased penetration of the tooth through earth formations while drilling.

Abstract: An earth-boring bit has a bit body that is threaded at one end for connection into a drill string. At least one cantilevered bearing shaft depends inwardly and downwardly from the bit body. A cutter is mounted for rotation on each bearing shaft and includes a plurality of cutting elements arranged in generally circumferential rows. At least one wear-resistant element is secured to the bit body between the lower end of the bit body and the threaded end, the wear-resistant element being elongate or generally oblong in cross-section.

Abstract: A drill bit including a roller cone and a plurality of cutting elements. The roller cone is affixed to a bit body and is arranged circumferentially about a bit axis of rotation. In one aspect, the cutting elements are arranged so that the crests of at least half of the cutting elements are within about 10 degrees of perpendicularity to the bit axis when each of these cutting elements is in a downwardmost rotary orientation. In another aspect, the roller cone and the cutting elements are arranged so that crests on the cutting elements define a substantially flat profile. Substantially flat in this aspect includes the profile having an endmost angle, either at the gage side or the centerline side, with respect to perpendicular to the bit axis, of less than about 11 degrees.

Abstract: A gage trimmer and a bit incorporating such a gage trimmer are provided. The gage trimmer has an ultra hard material layer having a circumferential surface including a cylindrical portion and a flat surface for bearing against a circumferential wall of a hole drilled by the bit. The ultra hard material layer is formed over a substrate interface surface. The flat surface does not extend to the interface surface.

Abstract: Disclosed is a polycrystalline diamond or diamond-like element with greatly improved wear resistance without loss of impact strength. These elements are formed with a binder-catalyzing material in a high-temperature, high-pressure (HTHP) process. The PCD element has a body with a plurality of bonded diamond or diamond-like crystals forming a continuous diamond matrix that has a diamond volume density greater than 85%. Interstices among the diamond crystals form a continuous interstitial matrix containing a catalyzing material. The diamond matrix table is formed and integrally bonded with a metallic substrate containing the catalyzing material during the HTHP process. The diamond matrix body has a working surface, where a first portion of the interstitial matrix in the body adjacent to the working surface is substantially free of the catalyzing material, and a second portion of the interstitial matrix in the body adjacent to the working surface contains the catalyzing material.

Abstract: A three cone roller bit with rolling cone cutters that are provided with both primary and secondary cutting elements. The primary cutting elements extend outwardly from lands on the outer surface of the cutter body. The secondary cutting elements are disposed within grooves on the cutter body so as to either protrude with its cutting surface from the bottom of the groove or be flush or slightly recessed within it. During normal operation, the primary cutter elements of the rolling cone cutters engage the borehole formation. The secondary cutters do not engage the formation. After substantial wear has occurred to the primary cutter elements, and wear begins to occur to the body of the cone cutters, the secondary cutter elements serve as a secondary cutting structure that engages and cuts into the formation.

Abstract: The invention concerns a self-penetrating drilling method and a thrust-generating tool: the tool (1) comprises N blades (2a, 2b, 2c, 2d). Each blade comprised K drill bits (3a, 3b, 3c, 3d). The shapes, positions and orientations of said drill bits are determined in the following manner: the kth drill bit of the last blade drills, at the (q−1)th of the tool rotational cycle, a cut in the rock downstream of the one produced by the (k+1)th drill bit of the first blade at the qth rotational cycle of the tool; the kth drill bit of the nth blade drills, at the q?th rotational cycle of the tool, a cut in the rock downstream of the one produced by the kth drill bit of the (n+1)th blade at the qth rotational cycle of the tool; the normal to the leading edge of the drill bit has a component along the axis of rotation oriented towards upstream.

Abstract: The invention is a roller cone drill bit including a seal adapted to seal between the bit body and a roller cone on the drill bit. The seal includes a seal body formed from a material that is adapted to energize the seal after compression of the seal. A first dynamic seal surface formed on the seal body and is adapted to seal against the bit body. A second dynamic seal surface is formed the seal body and is adapted to seal against the roller cone. The first and second dynamic seal surfaces are formed from a material adapted to withstand relative motion between the first dynamic seal surface and the bit body and between the second dynamic seal surface and the roller cone.

Abstract: A rotary cone bit, having a functionally-engineered surface of this invention, comprises a bit body having at least one leg extending therefrom, and a cone that is rotatably disposed on the leg. The cone typically comprises a plurality of cutting elements that project outwardly therefrom. The cutting elements comprises a cermet material selected from the group consisting of refractory metal carbides, nitrides, borides, carbonitrides and mixtures thereof. A functionally-engineered material is disposed over a surface portion of at least one of the cutting elements to form a wear resistant surface thereon. The wear resistant surface has a hardness that is different than that of the underlying cutting element. The wear resistant surface is provided by forming a conformable material mixture by combining one or more powders selected from the group consisting of cermets, carbides, borides, nitrides, carbonitrides, refractory metals, Co, Fe, Ni, and combinations thereof, with an applying agent.

Abstract: A graphite or silicate plug is coated with a refractory metal and positioned in the cutter pocket of a steel bodied bit as molten hardfacing material is applied to the bit surface under high temperature conditions. The refractory metal cooperates with the hardfacing material to act as a wetting agent that draws the hardfacing material into intimate contact with the body of the displacement plug. The plug is removed leaving a composite pocket opening formed by the steel body and the hardfacing material. A PDC cutter inserted into the composite pocket opening closely adheres to the sides of the opening to reduce the gap between the cutter and the hardfacing material to hereby minimize the effects of erosion in the area of the gap. The wetting material on the displacement plug permits the hardfacing material to flow into and remain in position immediately adjacent the displacement body and in the small surface area between adjacent cutter pockets.

Abstract: Using inserts which are welded in place allows the use of hardfacing in the immediate vicinity of the inserts. Areas of high wear, such as cutting structures and gage areas, can use a combination of ultra-hard inserts with hardfacing for protection against wear. The inserts slows wear, while the hardfacing prevents erosion around the inserts.

Abstract: A hardfacing composition for a drill bit is disclosed which includes a carbide phase made from about 80% to less than 100% by weight of a combination of sintered carbide pellets and crushed cast carbide and from more than 0% to about 20% by weight of carburized tungsten carbide. The composition includes a binder alloy. A roller cone drill bit includes a bit body and at least one roller cone rotatably mounted to the bit body. The at least one roller cone includes at least one cutting element. The cutting element has on its exterior surface a hardfacing. The hardfacing on the cutting element was formed with a hardfacing composition that includes a binder alloy and a carbide phase, which includes from about 80% to less than 100% by weight of a combination of sintered carbide pellets and crushed cast carbide, and from more than 0% to about 20% by weight of carburized tungsten carbide.

Abstract: In one embodiment, a method of increasing a durability of a drill bit having a bit body with at least one blade disposed thereon, at least one cutter pocket disposed on the blade, and at least one cutter disposed in the cutter pocket is disclosed. The method includes brazing the at least one cutter to the at least one cutter pocket so that a braze material disposed between the at least one cutter pocket and the at least one cutter comprises an exposed surface, and overlaying at least a portion of the exposed surface with a hardfacing material, wherein the hardfacing material includes a binder having a melting point selected to avoid damaging the cutter.

Abstract: A three cone roller bit with rolling cone cutters that are provided with both primary and secondary cutting elements. The primary cutting elements extend outwardly from lands on the outer surface of the cutter body. The secondary cutting elements are disposed within grooves on the cutter body so as to either protrude with its cutting surface from the bottom of the groove or be flush or slightly recessed within it. During normal operation, the primary cutter elements of the rolling cone cutters engage the borehole formation. The secondary cutters do not engage the formation. After substantial wear has occurred to the primary cutter elements, and wear begins to occur to the body of the cone cutters, the secondary cutter elements serve as a secondary cutting structure that engages and cuts into the formation.

Abstract: A novel and improved roller cone drill bit and method of design are disclosed. A roller cone drill bit for drilling through subterranean formations having an upper connection for attachment to a drill string, and a plurality cutting structures rotatably mounted on arms extending downward from the connection. A number of teeth are located in generally concentric rows on each cutting structure. The actual trajectory by which the teeth engage the formation is mathematically determined. A straight-line trajectory is calculated based on the actual trajectory. The teeth are positioned in the cutting structures such each tooth having a designed engagement surface is oriented perpendicular to the calculated straight-line trajectory.

Abstract: A roller cone drill bit in which the orientations of the teeth are varied within a single row, and/or between the heel row of one cone and the heel row of another cone, to prevent tracking.

Abstract: A drill bit comprising a bit body, at least one roller cone rotatably mounted on the bit body. The cone has a plurality of milled teeth at selected locations on the cone. At least one of the milled teeth comprises a substrate having a convex crest and a layer of hardfacing applied to said convex crest. The convex crest is adapted to produce at least one of a convex axial stress distribution, a substantially even axial stress distribution, and a substantially smooth axial stress distribution.

Abstract: A rotary drag bit and method for drilling subterranean formations including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: A rolling cone bit includes at least one cone cutter having a gage row of cutter elements and a first inner row of near but off-gage cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty so as to enhance bit durability, maintain borehole diameter and improve ROP. The off-gage distance of the first inner row of cutter elements is defined for various bit sizes to optimize the division of cutting duty. The distance that the first inner row of cutter elements are off-gage may be constant for all the cones on the bit or may be varied among the various cones to balance the durability and wear characteristics on all the cones of the bit.

Abstract: An insert for a rolling cone earth-boring bit has a cylindrical base that interferingly presses into a mating hole formed in a cone of the bit. The insert has a convex end that extends from the base. A polycrystalline diamond cap is bonded to the convex end. The body is formed of at least two layers of carbide material having different mechanical properties, particularly a different modulus of elasticity. The first layer may have a metallic binder with a lesser percentage than the binder of the second layer to reduce the stress at the interface between the first layer and the diamond cap. The layers may have different average carbide grain sizes, with finer average grain sizes adjoining the diamond cap. Further, the layers may have different binders, with cobalt being the binder in the layer adjoining the diamond cap and either nickel or a nickel-cobalt alloy in another layer.

Abstract: A drill bit for drilling casing in a well bore. The drill bit is constructed from a combination of relatively soft and relatively hard materials. The proportions of the materials are selected such that the drill bit provides suitable cutting and boring of the well bore while being able to be drilled through by a subsequent drill bit. Methods of applying hard materials to a soft material body are provided.

Abstract: A drill bit for drilling a borehole, the drill bit comprising a bit body 10 having an axis of rotation 12, a leading face, a plurality of blades 26 upstanding from the leading face, at least one of the blades terminating in a gauge pad 28 having a gauge surface 29 arranged, in use, to face a wall 30 of the borehole 32, the gauge surface 29 being devoid of cutting elements, the gauge surface 29 terminating at an end thereof remote from the blade at a junction 58 with a gauge pad end wall 56, wherein the gauge pad 28 carries a single cutter 62 having a face 64 and a cutting edge 65 located radially inward of the gauge surface 29, and wherein the junction 58 of the gauge surface 29 and the gauge pad end wall 56 crosses, radially, between the face 64 of the cutter 62 and the wall 30 of the borehole 32.

Abstract: A drill bit for drilling a borehole having a bit body with an axis of rotation, a leading face, and a plurality of blades upstanding from the leading face. At least one of the blades terminates in a gauge pad having a gauge surface arranged, in use, to face a wall of the borehole. The gauge surface being devoid of cutting elements and terminating at an end remote from the blade at a junction with a gauge pad end wall. The gauge pad carries a cutter having a face and a cutting edge located radially inward of the gauge surface, and the junction of the gauge surface and the gauge pad end wall crosses, radially, between the face of the cutter and the wall of the borehole. The gauge surface may be a substantially continuous surface, and may have at least one additional cutter located angularly between two adjacent blades of the drill bit.

Abstract: A boronized wear-resistant material that includes a boron-containing composition is disclosed. The boron-containing composition includes tungsten carbide and a compound represented by the formula W3MB3, where M is selected from the group consisting of iron, nickel, cobalt and alloys thereof. Particularly, a boride layer containing WC and W3CoB3 may be formed over a cemented tungsten carbide substrate by a suitable boronizing process. Additional compounds present in the boride layer include CoB, W2CoB2, and WB. A relatively thick and uniform boride layer may be obtained over a carbide substrate to form a wear-resistant body. Such a wear-resistant body may be used to manufacture cutting tools, drawing dies, inserts for an earth-boring bit, face seals, bearing surfaces, nozzles, and so on.

Abstract: Rock bits comprising wear and fracture resistant surface of this invention include a steel bit body having at least one leg extending therefrom. A steel cone is rotatably disposed on the leg. The steel cone includes a plurality of steel cutting elements that each projecting outwardly a distance therefrom. At least a portion of the cone comprises a wear resistant surface formed from a wear resistant composite material. The wear resistant composite material is made by the process of combining powders selected from the group consisting of carbides, borides, nitrides, carbonitrides, refractory metals, cermets, Co, Fe, Ni, steel, and combinations thereof, to form a material mixture. The material mixture is applied onto a designated surface of the cone, in one form or another, when the cone is in a pre-existing rigid state. Depending on the particular application, the material mixture can be applied in as a slurry to the designated surface of the cone to form a coating thereon.

Abstract: A method is disclosed for applying hardfacing to a shirttail portion of a roller cone drill bit, including masking around the shirttail portion of the bit and operating a high pressure/high velocity oxygen fuel torch to apply the hardfacing to the shirttail portion.

Abstract: A rolling cone bit includes at least one cone cutter having a gage row of cutter elements and a first inner row of near but off-gage cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty so as to enhance bit durability, maintain borehole diameter and improve ROP. The off-gage distance of the first inner row of cutter elements is defined for various bit sizes to optimize the division of cutting duty. The distance that the first inner row of cutter elements are off-gage may be constant for all the cones on the bit or may be varied among the various cones to balance the durability and wear characteristics on all the cones of the bit.

Abstract: A variety of large diameter PDC cutters for use in drill bits are disclosed. Specifically, various PDC cutters having a diameter between 19.0 mm and 25.0 mm are disclosed. The various PDC cutters disclosed include an elliptical PDC cutter, wherein a major diameter of the elliptical cutter is selected from a range of 19.0 mm to 25.0 mm, a circular PDC cutter, wherein a diameter of the circular cutter falls between 19.0 mm and 25.0 mm, and a non-planar substrate cutter, wherein a diameter of the non-planar cutter falls between 19.0 mm and 25.0 mm. Additionally, the thickness of the diamond table is increased as compared to prior art PDC cutters. The increase in diamond table thickness results in improved durability and performance.

Abstract: A new and useful purpose/process for Technogenia® and all its associated products. This applies to its use and application in Horizontal Directional Drilling (HDD) industry, vertical drilling, oil field industry, utility construction, mining industry, road/highway construction. The use and application applies to all tooling associated with these industries.

Abstract: Polycrystalline diamond (PCD) carbide composites of this invention have a microstructure comprising a plurality of granules formed from PCD, polycrystalline cubic boron nitride, or mixture thereof, that are distributed within a substantially continuous second matrix region that substantially surrounds the granules and that is formed from a cermet material. In an example embodiment, the granules are polycrystalline diamond and the cermet material is cemented tungsten carbide. PCD carbide composites of this invention display improved properties of fracture toughness and chipping resistance, without substantially compromising wear resistance, when compared to conventional pure PCD materials.

Abstract: A rotary-type drill bit for drilling subterranean formations having areas or components having surfaces exhibiting a relatively low adhesion, preferably nonwater-wettable, surface over at least a portion thereof.

Abstract: A design for a gage tooth of the milled tooth variety is provided. The gage facing surface of each tooth is shaped so that only a narrow surface of each tooth contacts the borehole wall. Adjacent areas on each tooth slope away from the wall. The narrow gage facing surfaces, the sloping areas, and other areas are all covered with a suitable hard metal facing material.

Abstract: The invention is a drill bit that has a bit body, at least one roller cone attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on the at least one roller cone. At least one bit design parameter is selected so that the cutting elements wear in a selected manner when drilling an earth formation.