Abstract: Hardfacing is used to protect wear surfaces of drill bits and other downhole tools. A hardfacing member can be formed by heating a metal matrix material, e.g., via a laser process, injecting a plurality of particles into the heated metal matrix material, disposing the mixture on at least a portion of a substrate thereby forming a hardfacing member having a particle-embedded metal matrix material, and attaching the hardfacing member to a main body.

Abstract: Embodiments disclosed herein relate to polycrystalline diamond compacts that have a substrate including a cementing constituent constituting less than 13 weight percent (wt %) of the substrate, the cementing constituent including a cobalt alloy having and at least one alloying element, wherein the at least one alloying element constitutes less than 12 wt % of the substrate and wherein the cobalt constitutes less than 12 wt % of the substrate; and methods of making the same.

Abstract: Polycrystalline diamond cutting elements having enhanced thermal stability, drill bits incorporating the same, and methods of making the same are disclosed herein. In one embodiment, a cutting element includes a substrate having a metal carbide and a polycrystalline diamond body bonded to the substrate. The polycrystalline diamond body includes a plurality of diamond grains bonded to adjacent diamond grains by diamond-to-diamond bonds and a plurality of interstitial regions positioned between adjacent diamond grains. At least a portion of the plurality of interstitial regions comprise a non-catalyst material, a catalyst material, metal carbide, or combinations thereof. At least a portion of the plurality of interstitial regions comprise non-catalyst material that coats portions of the adjacent diamond grains such that the non-catalyst material reduces contact between the diamond and the catalyst.

Abstract: A cutting element for an earth-boring tool includes a volume of superabrasive material on a substrate. The cutting element has an elongated shape in a lateral dimension parallel to a front cutting face of the cutting element, and has a maximum lateral width in a first direction parallel to the front cutting face of the cutting element and a maximum lateral length in a second perpendicular direction parallel to the front cutting face of the cutting element. The maximum lateral length is significantly greater than the maximum lateral width. An earth-boring tool includes one or more such cutting elements mounted to a body of the earth-boring tool. A method of forming such an earth-boring tool includes selecting at least one such cutting element and mounting the cutting element to a body of an earth-boring tool.

Abstract: An improved tooth for a roller crusher is presented. The tooth can include a first tungsten carbide overlay layer plasma-transfer arc welded on a recessed hemispherical end of the tooth, which is covered by a wearable cap placed over the first overlay layer, the cap welded to the tooth. A second tungsten carbide overlay layer can then be plasma-transfer arc welded over the cap to, thereby, provide a tooth having two tungsten carbide overlay wear layers.

Abstract: The present invention relates to a system and method for automated or “robotic” application of hardfacing to the surface of a steel-toothed cutter of a rock bit. In particular, the system incorporates a grounded adapter plate and chuck mounted to a robotic arm for grasping and manipulating a rock bit cutter beneath an electrical or photonic energy welding source, such as a plasma arc welding torch manipulated by a positioner. In this configuration, the torch is positioned substantially vertically and oscillated along a horizontal axis as the cutter is manipulated relative along a target path for the distribution of hardfacing. Moving the cutter beneath the torch allows more areas of more teeth to be overlayed, and allows superior placement for operational feedback, such as automatic positioning and parameter correction. In the preferred embodiment, sensors provide data to the control system for identification, positioning, welding program selection, and welding program correction.

Abstract: A hardfacing composition essentially consisting of from about 50 to 75 percent by weight of a carbide phase having a particle size distribution of ±20% or less of a median particle size; and from about 25 to 50 percent by weight of binder phase is disclosed. Drill bits having such hardfacing compositions disposed thereon are also disclosed.

Abstract: A modular cutting-teeth drill bit with controllable drilling specific pressure comprises a module (1), a modular unit (2), a bit body (3), conventional cutting teeth (4) and a nozzle (5). According to mechanical performance of the rocks in the strata drilled and requirements of drilling well, a combination of shapes, sizes and numbers of the module and the modular unit is optimized; effective abrasion edge length of the cutting element on a certain portion of the bit is controlled; and a constant specific pressure of the cutting element of the bit during the drilling process is maintained. The modular cutting-teeth bit substantially improves the effective abrasion volume of the cutting element, and improves the effective utilization rate of the cutting element.

Abstract: A hardfacing is provided to protect surfaces of drill bits and other downhole tools. The hardfacing may include tungsten carbide particles or pellets formed with an optimum weight percentage of binding material and dispersed within and bonded to a matrix deposit. The tungsten carbide particles may be formed by sintering or other appropriate techniques. The tungsten carbide particles may have generally spherical shapes, partially spherical shapes or non-spherical shapes.

Abstract: A reactive foil is used to assemble the components of rock bit cutters and to affix cutting elements to rock bit bodies. A small pulse of localized energy ignites the foil in a fraction of a second to deliver the necessary amount of heat energy to flow solder or braze and form a strong, true metallic joint. The reaction in the foil may be activated using optical, electrical, or thermal sources.

Abstract: A rotary drill bit includes a bit body substantially formed of a particle-matrix composite material having an exterior surface and an abrasive wear-resistant material disposed on at least a portion of the exterior surface of the bit body. Methods for applying an abrasive wear-resistant material to a surface of a drill bit are also provided.

Abstract: A rotary cone earth boring bit has at least one bit leg with a cone retaining ball passage that intersects an outer surface of the bit leg and is closed by a ball plug. An upwardly curved lower hardfacing bead is on the outer surface of the bit leg at least partially below the ball plug. A downwardly curved upper hardfacing bead is on the outer surface of the bit leg at least partially above the ball plug. The upper hardfacing bead has leading and trailing ends that join the lower hardfacing bead. The upper and lower hardfacing beads define a generally elliptical perimeter surround the ball plug. At least one transverse bead is above the upper hardfacing bead and leads generally upwardly and circumferentially from a leading edge of the bit leg to a trailing edge of the bit leg.

Abstract: An earth boring drill bit comprising a milled cutter having rows of teeth hardfacing guides on the cutter. Hardfacing is applied between adjacent teeth hardfacing guides to form a cutting element. The hardfacing may include an annular body with ridges that outwardly project from the body.

Abstract: An earth-boring bit has at least one steel tooth with a scoop-shaped profile. The scoop-shaped profile is formed by milling and hardfacing a tooth to have at least one flank with a concave profile. Additionally, the tooth may contain one flank with a concave profile and another with a convex profile. The centerline axis of the tooth may be moved to alter the angle between the flanks and the centerline to vary the manner in which the tooth engages the formation.

Abstract: A drill bit having a bit body having at least one blade thereon, at least one cutter pocket disposed on the at least one blade, at least one cutter disposed in the at least one cutter pocket, hardfacing applied to at least a selected portion of the drill bit is shown and described. The hardfacing includes a first hardfacing layer disposed on the selected portion of the drill bit, a second hardfacing layer disposed on the first hardfacing layer, wherein the first hardfacing layer has a hardness different than a hardness of the second hardfacing layer.

Abstract: A roller cone drill bit includes a bit body and at least one leg extending downward from the bit body. Each leg includes an outer surface, a ball hole plug located in the outer surface, a shoulder, a shirttail, and a roller cone rotatably mounted to the leg. The outer surface of each leg is surface processed by friction stirring.

Abstract: The present invention relates to a system and method for automated or “robotic” application of hardfacing to the surface of a steel-toothed cutter of a rock bit. In particular, the system incorporates a grounded adapter plate and chuck mounted to a robotic arm for grasping and manipulating a rock bit cutter beneath an electrical or photonic energy welding source, such as a plasma arc welding torch manipulated by a positioner. In this configuration, the torch is positioned substantially vertically and oscillated along a horizontal axis as the cutter is manipulated relative along a target path for the distribution of hardfacing. Moving the cutter beneath the torch allows more areas of more teeth to be overlayed, and allows superior placement for operational feedback, such as automatic positioning and parameter correction. In the preferred embodiment, sensors provide data to the control system for identification, positioning, welding program selection, and welding program correction.

Abstract: A hardfacing composition for a drill bit, including a carbide phase comprising from about 50% to about 75% by weight of the hardfacing composition of a combination of 16 to 40 mesh cemented tungsten carbide and 80 to 200 mesh super dense tungsten carbide cobalt particles, wherein about 5% to about 50% by weight of the carbide phase comprises the super dense tungsten carbide cobalt particles, and a binder alloy including about 25% to about 50% by weight of the hardfacing composition.

Abstract: An abrasive wear-resistant material includes a matrix and sintered and cast tungsten carbide pellets. A device for use in drilling subterranean formations includes a first structure secured to a second structure with a bonding material. An abrasive wear-resistant material covers the bonding material. The first structure may include a drill bit body and the second structure may include a cutting element. A method for applying an abrasive wear-resistant material to a drill bit includes providing a bit, mixing sintered and cast tungsten carbide pellets in a matrix material to provide a pre-application material, heating the pre-application material to melt the matrix material, applying the pre-application material to the bit, and solidifying the material. A method for securing a cutting element to a bit body includes providing an abrasive wear-resistant material to a surface of a drill bit that covers a brazing alloy disposed between the cutting element and the bit body.

Abstract: An ultra-hard and metallic construction comprises an ultra-hard component that is attached to a metallic component via a braze joint. The braze joint is interposed between the ultra-hard component and the metallic component, and comprises a first braze material bonded to a surface of the ultra-hard component. The braze joint includes an intervening layer in direct contact with the first braze material, and that is formed from a rigid material. The braze joint further comprises a second braze material that is interposed between the intervening layer and the metallic component, and that is different from the first braze material. Configured in this manner, the use of the braze joint operates to provide an optimum level of bond strength within the construction to enable its use in certain demanding wear and/or cutting applications.

Abstract: Roller cone bits 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 project outwardly a distance therefrom. At least one of the cutting elements comprises a steel base portion that is integral with the cone and that projects a distance therefrom. A cutting element end portion is attached to the base portion and extends therefrom to form a tip of the cutting element. The base and end portions are permanently attached together when the cone and base are in a preexisting rigid state. The cutting element end portion is formed from a wear resistant material having a material microstructure comprising a first phase of grains selected from the group of carbides, borides, nitrides, and carbonitrides of W, Ti, Mo, Nb, V, Hf, Ta, and Cr refractory metals; and a second phase of a binder material selected from the group consisting of Co, Ni, Fe, and alloys thereof.

Abstract: Composite constructions comprise a plurality of granules that are arranged together in a randomly-oriented manner. The granules each comprise an ordered arrangement of a first material phase and a second material phase, wherein the first and second material phases are each continuous, and each occupy different and distinct regions of the granule. At least a portion of the first and second material phases of each granule are in contact with one another. The first material phase comprises a material selected from the group consisting of cermet materials, polycrystalline diamond, polycrystalline cubic boron nitride, and mixtures thereof. The second material phase comprises a material that is relatively softer, e.g., more ductile, than the first material phase.

Abstract: A drill bit having a bit body having at least one blade thereon, at least one cutter pocket disposed on the at least one blade, at least one cutter disposed in the at least one cutter pocket, hardfacing applied to at least a selected portion of the drill bit is shown and described. The hardfacing includes a first hardfacing layer disposed on the selected portion of the drill bit, a second hardfacing layer disposed on the first hardfacing layer, wherein the first hardfacing layer has a hardness different than a hardness of the second hardfacing layer.

Abstract: An earth-boring bit has a body with three bit legs. A cone is rotatably mounted to each of the bit legs. Each of the cones has an outer row and an inner row of teeth machined on it. Each of the teeth has a rectangular root with inner, outer and lateral boundaries. A layer of hardfacing is applied to each tooth and on an exterior portion of each of the cones surrounding the inner, outer and lateral boundaries of each of the teeth. Conical surfaces between the inner and outer rows contain at least portions of the hardfacing.

Abstract: Composite constructions comprise a plurality of granules that are arranged together in a randomly-oriented manner. The granules each comprise an ordered arrangement of a first material phase and a second material phase, wherein the first and second material phases are each continuous, and each occupy different and distinct regions of the granule. At least a portion of the first and second material phases of each granule are in contact with one another. The first material phase comprises a material selected from the group consisting of cermet materials, polycrystalline diamond, polycrystalline cubic boron nitride, and mixtures thereof. The second material phase comprises a material that is relatively softer, e.g., more ductile, than the first material phase.

Abstract: Roller cone bits include a steel bit body having a leg extending therefrom. A steel cone is disposed on the leg and includes steel cutting elements projecting outwardly therefrom. One of the cutting elements comprises a steel base integral with the cone and that projects therefrom. A cutting element end is attached to the base portion and extends to form a cutting element tip. The base and end portions are attached when the cone base are in a preexisting rigid state. The end portion comprises a wear resistant material having a material microstructure comprising a first phase of grains selected from the group of carbides, borides, nitrides, and carbonitrides of W, Ti, Mo, Nb, V, Hf, Ta, and Cr refractory metals; and a second phase of a binder material selected from the group consisting of Co, Ni, Fe, and alloys thereof.

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: A method for manufacturing drill bits in segments, using a single key which is nowhere concave in its axial profile to position all three segments together for welding; and drill bits so made.

Abstract: A drill bit employing a plurality of discrete, post-like diamond grit impregnated cutting structures extending upwardly from abrasive particulate-impregnated blades defining a plurality of fluid passages therebetween on the bit face. PDC cutters with faces oriented in the general direction of bit rotation are placed in the cone of the bit, which is relatively shallow, to promote enhanced drilling efficiency through softer, non-abrasive formations. A plurality of ports, configured to receive nozzles therein are employed for improved drilling fluid flow and distribution. The blades may extend radially in a linear fashion, or be curved and spiral outwardly to the gage to provide increased blade length and enhanced cutting structure redundancy.

Abstract: A method of facing a substrate comprises the steps of first welding a body of a hard facing material to the substrate and then filling a space around the body with a molten metal. The method can be used in the hard facing of metal components with, for example, hard facing materials such as tungsten carbide. The substrate can comprise a metal surface, which can, for example, be the surface of any suitable component, tool, or implement subject to wear in use. The method is particularly suitable for hard facing the wear surfaces of components for use in drill strings in down-hole drilling technology, for example, drill stabilizers.

Abstract: An automated hardfacing system useful for hardfacing roller cones is disclosed. The automated system includes a robot with an arm, a positioner, and a controller which co-ordinates the alignment of the robot and the positioner. The robot holds a hardfacing torch and is capable of movement in three axes of movement. These axes are the x, y, and z axes of the Cartesian co-ordinate system. The positioner holds a roller cone and is capable of movement in at least two axes of movement. The movement includes tilting and rotation about a Cartesian axis. The hardfacing coating produced by the automated system has improved quality and consistency as compared to the one obtained by a manual process.

Abstract: A rotary cone drill bit includes at least one leg carrying a journal provided with bearing surfaces cooperating via bearing elements with bearing races in a rotatable cone cutter. The cone cutter is provided with rows of crushing elements. Each crushing element has a greatest width (D) and a greatest height (H), wherein HID<1.2. The crushing elements are welded to the body of the cone cutter to form a metallurgical bond therewith.

Abstract: An earth-boring bit has rolling cutters, each attached to a bit leg depending from a bit body. Each of the cutters has hardfaced, milled teeth. A spear point is located on one of the cutters. The spear point has a neck that protrudes toward the axis of the bit from a conical portion of the cutter. Blades are located on the spear point with spaces located between the blades. A layer of hardfacing is applied to the entire spear point area including the blades, the spaces and the neck.

Abstract: A method and apparatus are provided for use in fabricating rotary cone drill bits from multiple drill bit segments. Each drill bit segment (40) preferably includes a first portion (50) with mating surfaces (61, 62) designed to be aligned with mating surfaces (61, 62) of other drill bit segments (40) and a second portion (80) which includes a support arm (90) with a cutter cone assembly (100) rotatably mounted thereon. A recess (70) having a generally spherical surface is formed within the first portion (50) of each drill bit segment (40) such that when the respective drill bit segments (40) are aligned with each other, the spherical recesses (70) cooperate with each other to define a generally spherical cavity. A ball (72) is disposed within the resulting spherical cavity when the drill bit segments are joined with each other to form the bit body (42) for the resulting rotary cone drill bit (20).

Abstract: A roller cone or drag-type drill bit for use in drilling subsurface formations, especially useful for directional drilling, has a bit body with a shank portion for connection to a drill string, and a crown portion. Breaker slots are formed in the bit body at or immediately adjacent to the intersection of the crown portion and the shank portion. This location of the breaker slots allows the drill bit to be relatively shorter than comparable prior art bits with the breaker slots formed in the shank portion. The shorter length permits the present drill bit to be more easily steered in directional drilling applications.

Abstract: An earth-boring bit has a bit body and at least one cutter rotatably secured to the bit body. The cutter includes a plurality of teeth formed integrally with the cutter and arranged in circumferential rows. Each tooth has inner and outer ends, leading and trailing flanks, and a crest transversely connecting the ends and flanks. A thickness of wear-resistant material is applied over the crest and at least a portion of the ends and flanks of the tooth. An extending layer of wear-resistant material is applied at the intersection of the leading flank and the outer end to provide twice the hard-facing thickness and increased wear-resistance in that area of the tooth that is subjected to the greatest wear.

Abstract: Hardfacing to protect wear surfaces of drill bits and other downhole tools having coated diamond particles dispersed within and bonded to a metallic matrix deposit. The coating on the diamond particles may be formed from materials and alloys such as particles, tungsten carbide, and tungsten carbide/cobalt and cermets such as metal carbides and metal nitrides. The coated diamond particles are preferably sintered and have a generally spherical shape. The coated diamond particles are premixed with selected materials such that welding and cooling will form both a metallurgical bond and a mechanical bond within the solidified metallic matrix deposit. A welding rod is prepared by placing a mixture of coated diamond particles, hard particles such as tungsten carbide/cobalt, and loose filler material into a steel tube.

Abstract: A drill bit (20) for a modular arm (70) is provided. The modular arm (70) includes an inside surface (76) having first (144) and second (146) angled surfaces whose lower portions form an inwardly projecting wedge (125). A curved throat relief area (87) connects to a lower edge (152) of the wedge (125). A pocket (54) in the drill bit (20) is sized to receive the support arm (70). The pocket (54) includes a wedge-shaped recess (121) sized to receive the wedge (125) of the support arm (70). A triangular weld groove (126) is provided in the convex surface of the bit body (40). A length of weld (128) is applied in the weld groove (126) for firmly securing the support arm (70) to the bit body (40).

Abstract: A rotary cone drill bit having a one-piece bit body with a lower portion having a convex exterior surface and an upper portion adapted for connection to a drill string. The drill bit will generally rotate around a central axis of the bit body to form a borehole. A number of support arms are preferably attached to pockets formed in the bit body and depend therefrom. The bit body and support arms cooperate with each other to reduce initial manufacturing costs and to allow rebuilding of a worn drill bit. Each support arm has an inside surface with a spindle connected thereto and an outer shirttail surface. Each spindle projects generally downwardly and inwardly with respect to the longitudinal axis of the associated support arm and the central axis of the bit body. A number of cone cutter assemblies equal to the number of support arms are mounted respectively on each of the spindles.

Abstract: A milled tooth (22) is provided having a back face (38), including an upper back face surface (58) and a lower back face surface (60). A tip or top surface (36) is provided below the upper back face surface (58). The upper back face surface (58) is in a recessed position relative to the lower back face surface (60). A gage rib guide (64) runs along one side of the lower back face surface (60). A layer of hardfacing material (33) is applied to the milled tooth (22) so that the layer (72) applied to the lower back face (60) surface is flush with the gage rib guide (64) and the layer (74) of hardfacing material (33) is thickest in the region of the upper back face surface (58).

Abstract: A rotary cone drill bit for forming a borehole having a bit body with an upper end portion adapted for connection to a drill string. A number of support arms extend from the bit body. Each support arm has an exterior surface. A number of cutter cone assemblies equal to the number of support arms are mounted respectively on the support arms and project generally downwardly and inwardly with respect to an associated support arm. A ramp is formed on the exterior surface of the support arm and is inclined at an angle from a leading edge of the support arm toward a trailing edge of the support arm such that the ramp directs cuttings upward in the borehole.

Abstract: A method of manufacturing a rock bit leg from a rough bit leg forging is disclosed whereby multiple machining operations are performed by a six-axis CNC machining center. Three dimensional datum surfaces are initially formed on a rough leg forging. The rough leg forging is then mounted in a holding fixture. The fixture, including the leg forging, is secured to the six-axis CNC machining center. A three dimensional datum reference from the leg forging is set into the NC function of the six-axis machining center.The rough leg forging includes a pair of extended flanges coincident with the 120.degree. leg surfaces. The leg flanges mount to complimentary surfaces formed on the leg holding fixture, thus securing the leg within the fixture without interference of any of the machining processes.The CNC machining center performs a majority of the material removal operations to prepare the leg for subsequent assembly through manipulation of the six interactive axes of the CNC machining center.

Abstract: Drill bits having projecting inserts are completely coated with refractory material including on the edge margins about the inserts by thermally spraying with refractory particles whose particulate constituent under the spraying conditions is able to penetrate the inserts. Completely coated drill bits are provided.

Abstract: A rock bit employs cemented tungsten carbide inserts for engaging a rock formation for drilling oil wells or the like. The cemented tungsten carbide inserts have as a binder phase a cobalt base alloy including from 10 to 35% by weight nickel, from 3 to 10% by weight chromium, from 1 to 6% by weight of molybdenum, and a balance primarily of cobalt. A particularly preferred composition has 6% by weight chromium, 17% by weight nickel, 4% by weight molybdenum and a balance of cobalt. Wear resistance is enhanced without loss of toughness in the inserts.

Abstract: A rotary cone rock bit featuring a reproducible geometry and a one piece body is disclosed. Individual journal members, supporting rotary cutting cones, have upwardly extending structural shanks which are radially oriented and installed into downwardly directed individual hubs formed by the structural body of the rock bit. The shanks are subsequently secured as installed within the hubs. The primary controls over bit geometry comprise the radial orientation of the individual journal member, and the radial location of the individual hubs relative to the vertical bit body centerline.

Abstract: A cemented carbide tip for a cutter bit is rotationally symmetric about its longitudinal axis and has a socket in its rear end for brazing to a steel protrusion on a steel tool shank. The tip socket and an outer rearmost facing surface on the tip rear end have respective pluralities of first and second bumps thereon for spacing, centering and aligning the tip on the bit body to facilitate formation of a braze joint of a desired given cross-sectional thickness profile between the tip and bit body.

Abstract: The disclosed invention describes a method for cladding surfaces of an earth boring apparatus, or the like, with a hardfacing material having an entrained, or encapsulated, heavy metal refractory carbide. The method includes heating the surface to the incipient melting temperature and applying a molten super-alloy matrix material that has a melting temperature below the melting temperature of the carbide. The super-alloy, in a powder form, is pre-mixed with the carbide material, also in a powder form, such that, when the molten surface and the molten super-alloy cool, they form a metallurgical bond, at the surface, with the carbide material mechanically retained within the solidified matrix material.

Abstract: A method for manufacturing an earth boring drill bit and bit produced thereby are shown. The bit has rotatable cutters with a plurality of milled teeth, each of the teeth having opposing flanks. A first tube hardfacing is applied to a selected one of the opposing flanks, the hardfacing comprising a metallic binder with wear-resistant particles dispersed throughout the binder. The other of the opposing flanks has a second tube hardfacing applied thereto. The particle size of the wear-resistant particles differs between the first and second tube hardfacings so that the resulting difference in abrasion resistance of the tooth flanks produces a self-sharpening effect as the tooth wears.

Abstract: In a method of assembling a roller cone type rock bit, on a body having a tool joint adjacent one end and at least one leg portion adjacent the other end, the leg portion is provided with a longitudinally outer surface which is inclined longitudinally inwardly from its radially outer extremity to its radially inner extremity; on a base for a cone assembly, an end surface is provided configured to mate with the outer surface of the leg portion of the body; a roller cone is rotatably mounted on the base distal the end surface to form a cone assembly, and the end surface of the base is mated with the outer surface of the leg portion; the base is then welded to the leg portion along the juncture of the mating surfaces to mount the cone assembly on the leg portion.

Abstract: A method of forming a cutting structure for a rotary drill bit comprises brazing a thermally stable polycrystalline diamond cutting element to a carrier, the carrier being formed of a material such that, at the brazing temperature, the difference in coefficient of thermal expansion between said material and the polycrystalline diamond material is less than the difference in coefficient of thermal expansion between tungsten carbide and the polycrystalline diamond material. A suitable carrier material is silicon carbide.