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: A wear resistant drill bit of the matrix bodied type has a bit body comprising a tungsten carbide material bound with a binder material, wherein the tungsten carbide material includes at least some tungsten carbide particles of generally spherical shape. The tungsten carbide material includes particles having a relatively hard central core and a softer skin. The skin includes a large proportion of a high temperature phase of tungsten carbide.

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: The objects of the invention are: a weld overlay having stable quality is provided; cracks which have been created on a weld overlay during engagement of a part with its mating member are prevented from extending; and adverse effects on the wear of mating member are avoided. A weld overlay containing hard particles is formed on each tooth of a sprocket 6 such that each bead extending a direction (direction B) perpendicular to the rotating direction of the sprocket 6. A weld overlay containing hard particles is formed on the outer peripheral surface of a bushing such that each bead extends in a direction perpendicular to the rotating direction of the sprocket, the outer peripheral surface serving as a contact surface for the sprocket which engages with the bushing.

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 roller bit is provided having super-abrasive inserts on cutting portions to assure that the bit will maintain cutting efficiency. In the described exemplary bits, the axes of the roller cones are also offset by a significant or “high offset” amount from the central longitudinal axis of the bit, thereby providing for increased shearing and grinding action by the bit. The use of high offset in combination with super-abrasive inserts provides for optimal bit cutting designs which provide increases in ROP while preserving the bit's ability to hold gage and remain durable to achieve acceptable footage. Minimum high offsets and preferred high offsets are described for various bit sizes, designs and nomenclatures, including milled tooth bits and insert-type bits designed for use in soft-through-medium formation hardnesses as well as formations with greater hardnesses.

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 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: The invention is directed to a roller cone drill for drilling earth formations. The drill bit includes a bit body and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The drill bit further includes a plurality of teeth disposed on each of the roller cones such that the number of teeth on each cone differs by two or fewer from the number of teeth on each of the other cones. In one preferred embodiment, the drill bit includes three roller cones. In another preferred embodiment, the teeth of the bit are arranged on each cone so that teeth on adjacent cones intermesh between the cones. In another preferred embodiment, the drill bit includes a first cone, a second cone, and a third cone, and the number of teeth on each of the cones is 17, 16, and 18, respectively.

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 drill bit insert has a cylindrical barrel, a bevel on one end, an interface therebetween, and a cutting tip opposite the bevel. The bevel and interface contact the entrance to a hole in the drill bit and facilitate the transition of the barrel into the hole. A high quality surface finish on the bevel and interface enhance the durability and retention of the insert in the drill bit. The surface finish on the insert is produced by polishing it with a diamond lapping film. The insert is rotated between three rollers as the lapping film passes over its surface. One of the rollers and the film conform to the axial profile of the insert as each element rotates so that the interface, bevel, and barrel of the insert are simultaneously polished.

Abstract: An earth-boring bit has hardfacing that has multiple grades and an overlapped portion. One of the layers is of a different grade than the other so as to provide more wear resistance. The other provides more toughness than the wear resistant layer. The more wear resistant layer has a greater volumetric density of carbide particles. The greater density is primarily achieved by using a majority of the particles of smaller dimension than in the less wear resistant hardfacing. The overlapped portion may be on an outer or gage end of the outer row of teeth.

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: There is now provided a twist drill having an elongate body at a first end, a shank at a second and opposite end, the elongate body and the shank sharing a common axis, at least one face on the elongate body at an end opposite the shank, wherein the at least one face defines a corresponding flute extending along the elongate body toward the shank, at least one flank on an end of the elongate body at an end opposite the shank, and a cutting edge at a juncture of the at least one face and the at least one flank, and the like tools, having a sintered cemented carbide body, and the use thereof in material removing and dislodging tools.

Abstract: Composite constructions of this invention comprise a first structural phase formed from a hard material selected from the group consisting of cermet materials, polycrystalline diamond, polycrystalline cubic boron nitride, and mixtures thereof, and a second structural phase formed from a material that is relatively softer than that used to form the first structural phase. The material selected to form the second structural phase can be the same or different from that used to form the first structural phase. The second structural phase is positioned into contact with at least a portion of the first structural phase. The composite construction includes repeated structural units that each comprise an ordered microstructure of first and second structural phases.

Abstract: Disclosed is a tooth type rolling cutter earth boring drill bit with secondary cutting elements on the tooth surfaces. The secondary cutting elements provide additional, relatively sharp edges that help cut hard rock. The teeth also have convex radiused buttresses at their bases to reduce the stresses the teeth experience when drilling through extremely hard rock. This allows the tooth bit to survive the high loads encountered when drilling hard, tough rock formations, without breaking the teeth. The combination of teeth with secondary cutting elements and convex radiused buttresses at their base provide a tooth type rotary drill bit that has superior resistance to wear and breakage when drilling through hard, tough rock without significantly reducing the drilling rate of penetration when drilling through soft rock.

Abstract: A cutter element for use in a drill bit, comprising a substrate and a plurality of layers thereon. The substrate comprises a grip portion and an extending portion. The layers are applied to the extending portion such that at least one of the layers is harder than at least one of the layers above it. The layers can include one or more layers of polycrystalline diamond and can include a layer in which the composition of the material changes with distance from the substrate.

Abstract: This invention relates to a roller bit applying for the oil, natural gas, mine and geological drilling, and more particularly relates to a kind of roller bit with the parallel inlayed compacts, it includes head and cone, the compact land and the teeth-groove are arranged on the cone, the difference is that there are 2 to 3 compacts having the cylindrical body being arranged on the top of the base teeth along the teeth direction. The cutting performance of the present invention is similar to that of the oblate compacts, and, by utilizing the conventional cylindrical compacts, it is not only easy to process and with low manufacturing cost, but the bit can effectively drill through the stringered earth formation with both hard and soft formation and thus better economic benefit from drilling the stringered formation can be obtained.

Abstract: A method is disclosed comprising the steps of locating, on a surface of a downhole component, a plurality of thermally stable polycrystalline diamond (TSP) bearing elements, and then applying to the surface a settable facing material which bonds to the surface between the bearing elements and embraces the elements to hold them in place. A method in which bearing elements each comprising a body of TSP at least partly surrounded by a layer of less hard material are secured to the surface by welding or brazing part of the surface of each bearing element which comprises said less hard material to said component is also described.

Abstract: A cutter element for a drill bit. 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: A new composition for making an improved high-strength matrix body and methods of making the matrix body are disclosed. The new composition includes large-grain carburized tungsten carbide, an infiltration binder, and optionally cast tungsten carbide. The high-strength matrix body is formed from the new composition by an infiltration process. Suitable infiltration binders include all transition metals and all main group metals. To obtain optimal physical properties, large-grain carburized tungsten carbide is mixed with cast tungsten carbide and Ni powder before infiltration. The high-strength matrix body has improved braze strength. Such matrix bodies are suitable for manufacturing bit bodies for PDC drill bits and other earth-boring devices.

Abstract: A method of applying a wear-resistant material to a surface of a downhole component for use in subsurface drilling comprises forming a plurality of bearing elements, applying a layer of an electrically conductive, less hard material to each bearing element, and then bonding each bearing element to the surface of the component by welding or brazing to the surface of the component a part of the surface of the bearing element which comprises said less hard material, wherein the layer is of thickness greater than 0.05mm.

Abstract: A roller cone for a rock bit is disclosed. The cone includes a cone substrate and hardfacing applied by a welding process in grooves on the exterior surface of the cone substrate. The cone also includes hardfacing applied by a thermal spraying process to insert lands on the exterior surface of the cone substrate.

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 reduces the stress at the interface between the first layer and the diamond cap. The layers may have different average carbide average 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 rotary cone drill bit is provided with at least one cutter cone assembly having a machined cutting structure which will maintain an effective cutting profile despite abrasion, erosion and/or wear of the associated cutting elements. The machined cutting structure may be formed on a generally cone shaped blank by a series of lathe turns and/or plunge cuts. The cutting elements may be formed with an aggressive cutting profile. For one application, the crest of each cutting element has the general configuration of an ogee curve. A layer of hardfacing material may be applied over all or selected portions of the machined cutting structure.

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 hardfacing composition for an earth-boring bit has a quantity macrocrystalline tungsten carbide particles and a quantity of spherical cast tungsten carbide pellets. The particles and pellets are contained within a metal matrix which forms the balance of the composition.

Abstract: Superhard material enhanced inserts and methods of making the same have been disclosed. The enhanced insert includes a body portion adapted for attachment to the earth-boring bit and a top portion for contacting an earthen formation to be drilled. The top portion includes a substrate and a layer of superhard material over a portion of the substrate other than in central region of the outer lateral face. For example, a layer of polycrystalline diamond is provided in the leading transition of the top portion, whereas the trailing transition and the central region of the outer lateral face of the top portion are substantially free of polycrystalline diamond.

Abstract: A method is disclosed comprising the steps of locating, on a surface of a downhole component, a plurality of thermally stable polycrystalline diamond (TSP) bearing elements, and then applying to the surface a settable facing material which bonds to the surface between the bearing elements and embraces the elements to hold them in place. A method in which bearing elements each comprising a body of TSP at least partly surrounded by a layer of less hard material are secured to the surface by welding or brazing part of the surface of each bearing element which comprises said less hard material to said component is also described.

Abstract: A cutting element substrate for use with an earth-boring drill bit. The substrate includes a base, or outer shell, with a cavity opening to an end thereof. The base is fabricated from an erosion-resistant and abrasion-resistant material. A core that is configured substantially complementarily to the cavity is disposed within the cavity. The core base is fabricated from a material that is more ductile than the material of the base. The core and base each includes a cutting end to which a superabrasive cutting table, such as a polycrystalline diamond compact, may be secured. The substrate may be secured within a corresponding receptacle of a bit body in order to secure a superabrasive cutting table to the bit body in a desired orientation. The present invention also includes methods of fabricating the cutting element substrate.

Abstract: An earth-boring bit has a bit body with at least one earth disintegrating cutter mounted on it. The cutter is generally conically shaped and rotatably secured to the body. The cutter has a plurality of teeth formed on it. The teeth have underlying stubs of steel which are integrally formed with and protrude from the cutter. The stubs have flanks which incline toward each other and terminate in a top. A carburized layer is formed on the flanks and the top to a selected depth. The stub has a width across its top from one flank to the other that is less than twice the depth of the carburized layer. A layer of hardfacing is coated on the tops and flanks of the stub, forming an apex for the tooth.

Abstract: A method of manufacturing a rolling cone with hard-facing coating for use in drilling boreholes is disclosed. The method includes a step of depositing a layer of hardfacing material by an arc process, e.g., a gas-shielding tungsten arc welding process, a plasma-transferred arc welding process, or a metal inert gas arc welding process, over areas susceptible to erosion on the rolling cone surface. A rolling cone rock bit for drilling boreholes with a layer of hardfacing material deposited by an arc process either on the lands or in grooves or both of the cone surface is provided. Furthermore, a cone for attachment to the bit body of a rock bit with a layer of hardfacing material deposited on selected lands or in selected grooves or both of the cone surface also is provided.

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: A rotary drill bit suitable for directional drilling. The bit includes a bit body from which extend legs carrying rotatable cutters. The body carries primary gage pads, above which secondary gage pads may be either longitudinally spaced or rotationally spaced, or both. Longitudinally leading edges of the gage pads may carry cutting structure for smoothing the sidewall of the borehole. Cutting structure may likewise be disposed on the trailing ends of the gage pads to provide an up-drill capability to facilitate removal of the bit from the borehole. The gage pads provide enhanced bit stability and reduced side cutting tendencies, as well as reducing lateral loading on the rotatable cutters and associated bearing structure and seals. The invention also has utility in bits not specifically designed for directional drilling.

Abstract: An insert is provided for a rock bit for drilling bore holes in the ground and other downhole tools. The cutting portion of the inserts consist of encrusted cubic boron nitride pellets, tungsten carbide particles and a binder material which are fused together to form a unitary body. The cubic boron nitride particles of the fused insert are cubic in structure and substantially free of heat degradation and resultant hexagonal crystalline structure in response to fusing the elements together in a single step of simultaneously heating and compacting the elements.

Abstract: A rotary drill bit is manufactured by a powder metallurgy process by placing a metal mandrel in a mold, packing the mold with particulate matrix-forming material, infiltrating the material with a molten binding alloy, and cooling the assembly to form a solid infiltrated matrix bonded to the mandrel. The mandrel comprises an outer part surrounded by the matrix-forming material and an inner part, secured to the outer part but out of contact with the matrix-forming material. The outer part of the mandrel is formed from a material having thermal characteristics close to those of the matrix, so as to reduce the tendency for the matrix to crack under thermal stress, while the inner part of the mandrel is formed from a precipitation-hardening material, the strength and hardness of which increases in the infiltration process and the subsequent heating/cooling cycle for brazing the cutters on to the drill bit.

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

Abstract: A fixed-cutter drill bit for boring through earth has a body made predominately of high strength steel with thin erosion and abrasion resistant surfaces integrally formed in the steel in areas likely to encounter abrasive or erosive conditions. The drill bit may be formed by a rapid solid state densification (RSSDPM) process. The drill bit combines the high strength of conventional steel bits with design freedom and hardness equal to or greater than conventional matrix bits. Due to the manner in which the hard particles, such as tungsten carbide, are integrally held in a steel matrix, aggressive fluid hydraulics may be employed with the drill bit without unduly limiting the performance of the drill bit.

Abstract: A drill bit for boring a bore hole in an earthen formation comprises: a bit body having a pin end, a cutting end and a longitudinal bit axis and including at least two legs extending from the cutting end, each of the legs including a bearing that rotatably supports a cutter cone. The bit body further includes a fluid flow system, including a flowway in said pin end that is in fluid communication with at least one exit port in the cutting end, the exit port being defined by a nozzle boss and disposed adjacent one of the legs. Each of the legs includes a leading side surface, a trailing side surface, and a center panel, and at least one of said legs is asymmetric such that its trailing side surface is larger than its leading side surface. The present bit can also include a lubricant system that has its opening in the trailing side of the leg, and can further include various wear resistant coatings and inserts on its surface.

Abstract: An earth-boring bit has a bit body with at least one bearing shaft depending inwardly and downwardly therefrom. A cutter is mounted for rotation on each bearing shaft and has a cutter shell surface and a plurality of cutting elements arranged on the shell surface in generally circumferential rows. A pair of surfaces extends from the cutter shell surface on opposing sides of one of the circumferential rows of cutting elements. The pair of surfaces converge together to define a kerf crest that is oriented transversely to the axis of rotation of the cutter. The kerf crest projects from the cutter shell surface by an amount less than the cutting elements in the kerf row having the kerf crest.

Abstract: An earth-boring bit has a bit body and a cantilevered bearing shaft depending from the bit body. The cutter is mounted for rotation on the bearing shaft. Cutting elements are secured within holes formed in the cutter. At least some of the cutting elements include a body of hard metal which has a cylindrical base inserted in an interference fit within one of the holes. The body has a contact surface on its cutting end. A layer of super-hard material is bonded to the contact surface to provide a tip for the cutting end. The layer may be formed of a free-standing film of diamond which is brazed to the contact surface. It may also be formed with a high temperature, high pressure process directly onto the body of tungsten carbide.

Abstract: The improved insert for a ground engaging tool, with a plurality of sockets for receiving a respective insert comprises a body having first and second portions and first and second zones. The first zone may consist of tungsten carbide and metallic cobalt, with preselected dimensions adapted for press fitting within a respective socket of the ground engaging tool. The second body portion may define an earth engaging portion. The second zone may consist of encrusted diamond pellets, tungsten carbide and metallic cobalt, fused together. The first and second zones may be fused together with the first zone being substantially free of encrusted diamond pellets.

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: An earth-boring bit has cutting elements inserted within holes in the cutter support. The cutting element has a body of a fracture-tough material, preferably tungsten carbide which contains a binder of a soft metal. A layer of a composite carbide which is substantially free of a binder is attached to the cutting end of the body. One cutting element has a chisel-shaped cutting end with two flanks that converge. One of the flanks has the layer of binderless carbide. This insert is located at a junction between the gage surface and heel surface for engaging the sidewall of the bore. Also, gage inserts located in the gage surface have outer ends containing a layer of binderless carbide.

Abstract: An earth-boring bit has a bit body which connects to a drill string. Three cutters are rotatably secured to a bearing shaft of the bit and a large number of chisel-like cutting elements are secured to each cutter. Each cutting element has a cylindrical base and a cutting end. An elongate crest is located at the tip of the cutting end. A conical chamfer connects the crest and the cutting end. The junction created by the chamfer is non-tangential and reduces the amount of unsupported material at the crest. The conical contour of the chamfer is defined by by a straight line moving in an oval path about the longitudinal axis. The contour of the cutting end avoids abrupt changes and associated stress concentrations. This is achieved by avoiding surfaces of rotation in non-axisymmetric configurations.

Abstract: A steel tooth particularly suited for use in a rolling cone bit includes a parent metal core having an inner gage facing surface, leading and trailing edges, a root region adjacent to the cone and an outer most edge spaced from the root region. A hardfacing layer that includes at least two hardfacing materials having differing wear characteristics is disposed over the parent metal core in an asymmetric arrangement of regions of the first and second materials. A first of the hardfacing materials has a higher low stress abrasive wear resistance than that of the second material. The second material has a high stress abrasion resistance that is greater than the first material. The first and second materials are applied in generally contiguous regions over the entire gage facing surface of the parent metal core so as to optimize regions of the tooth for the particular cutting duty experience by that region.

Abstract: A rotary tool that includes an elongate tool body and a hard insert affixed to the tool body is disclosed. The hard insert includes a WC-cermet including tungsten carbide and about 5 wt. % to 19 wt. % Co--Ni--Fe-binder. The Co--Ni--Fe-binder is unique in that even when subjected to plastic deformation, the binder substantially maintains its face centered cubic (fcc) crystal structure and avoids stress and/or strain induced transformations.

Abstract: Steel bit bodies are manufactured in a production process that employs polystyrene patterns in a lost foam casting process. The patterns are machined to permit the formation of complex shapes that cannot be reproduced in simple patterns that are extractable from reusable, two-piece pattern molds or dies. The patterns are machined from a billet material according to a basic, programmed, five-axis machining process to form multiple copies of a reproducible complex pattern body. The process is modified to produce multiple copies of a modified design. Machining the complex patterns and producing variations by changing the machine program permit multiple bit patterns of variable forms to be produced without need for building an intermediate, reusable pattern mold that would require multiple mold pieces, thus eliminating the associated time and expense required in the creation of a new pattern mold for each variation of the bit design.

Abstract: A steel tooth rolling cutter earth boring drill bit includes a bit body with a threaded upper end for attachment to the end of a drill string, and a lower end including three legs extending downwardly from the bit body and with a rolling cutter rotatably mounted on each leg. A layer of wear resistant material is applied to a portion of each rolling cutter and comprises wear resistant particles in a substantially steel matrix. The steel matrix is integrally formed with the cutter in a rapid, solid state densification powder metallurgy (RSSDPM) process, and includes a duplex microstructure comprising from about 10 to 40 volume percent austenite and from about 60 to 90 volume percent martensite. The duplex microstructure may be achieved by incorporating a minor fraction of pure nickel and/or manganese powder in the powder mix used in the process, thereby providing nickel or manganese enrichment of the austenitic zones of the matrix.

Abstract: An earth-boring bit has a rotating cutter of a hybrid design. The bit has a bit body and a bearing shaft which is cantilevered downwardly and inwardly from the bit body. The cutter is mounted for rotation on the bearing shaft and has a plurality of cutting elements arranged in circumferential rows on the cutter. These rows include inner rows and a heel row. The cutting elements in the inner row are formed of a hard metal such as tungsten carbide and are pressed interferingly into apertures in the cutter. The heel row is made up of steel teeth formed on the cutter.