Abstract: A cutter element for a drill bit includes a base portion having a central axis, a first end, and a second end. In addition, the cutter element includes a cutting layer fixably mounted to the first end of the base portion. The cutting layer includes a cutting face distal the base portion. The cutting face includes an elongate raised ridge having a first end at a radially outer surface of the cutting layer and a second end at the radially outer surface of the cutting layer. The raised ridge defines a maximum height of the cutter element measured axially from the second end of the base portion to the cutting face. The cutting face also includes a first planar lateral side surface and a second planar lateral side surface. Each planar lateral side surface extends from the raised ridge to the radially outer surface of the cutting layer.

Abstract: A combustor for a turbine engine is provided, the combustor includes an outer liner, an inner liner and a dome that together define a combustion chamber; a diffuser positioned upstream of the combustion chamber, the diffuser being configured to receive air flow from a compressor section and to provide a flow of compressed air to the combustion chamber; and an outer cowl and an inner cowl located upstream of the combustion chamber, the outer cowl and the inner cowl being configured to direct a portion of air flow from the diffuser to the combustion chamber. The diffuser is configured to output air flow having an amount of air pressure maximized at a center of the air flow so as to optimize total air pressure fed to the combustion chamber through the dome.

Abstract: Methods for manufacturing a matrix tool body comprising placing a first matrix material within a first region of a mold cavity proximate a surface of the mold. A second matrix material may be placed within a second region of the mold cavity positioned inwardly of the first matrix material. The first matrix material and the second matrix material comprise a plurality of hard particles. The plurality of hard particles of the second matrix material have a median particle size that is less than the median particle size of the first matrix material. The plurality of hard particles of the first matrix material and the second matrix material are infiltrated with an infiltration binder to form the tool body. Also included are tool bodies having one or more regions proximate a surface of the tool body comprising an erosion resistant matrix material and/or a wear resistant matrix material.

Abstract: A tool for drilling subterranean formations includes a tool body having a face surface, a blade extending radially outward on the face surface toward a gage surface, and a plurality of cutting structures disposed in the blade. Each of the plurality of cutting structures comprises a substantially spherical body of particulate impregnated matrix material. A method of forming the tool includes forming a tool body having the plurality of cutting structures dispersed therein. A method of using the tool includes rotating the earth-boring tool within a wellbore and engaging a formation material of an earth formation with an outer surface of the blade and wearing the outer surface of the blade to expose the spherical cutting structure. After wearing the outer surface of the blade, the method includes engaging the earth formation with the spherical cutting structure.

Abstract: A downhole tool, such as a fracture plug used during a fracture operation, installs in a downhole tubular, such as casing. The tool has a mandrel with a sealing element disposed thereon between uphole and downhole ends. Slip assemblies on the mandrel can be moved to engage the downhole tubular. When the tool is used as a bridge plug, the uphole assembly supports the sealing element compressed, and the downhole assembly supports fluid pressure downhole of the tool. The slip assemblies have inserts composed of at least two materials that are different from one another and are geometrically separate from one another. In addition or as an alternative, the slip assemblies can be composed of at least two different materials that are geometrically separate from one another.

Abstract: A drill bit for cutting a hole in a formation. The drill bit has a shank and a crown. The crown has a plurality of crown portions that are spaced about an operative circumference of the drill bit. The shank and crown cooperate to define an interior space that receives water or other drilling fluid. Each crown portion has two longitudinal edges, an outer surface, at least one inner surface and a cutting face. The crown has a base surface that is spaced from the cutting faces of the crown portions and cooperates with the inner surface of each of the two crown portions to define a slot.

Abstract: Earth-boring tools include a cutting element mounted to a body that comprises a metal or metal alloy, such as steel. A cutting element support member is mounted to the body rotationally behind the cutting element. The cutting element support member has an at least substantially planar support surface at a first end thereof, and a lateral side surface extending from the support surface to an opposing second end of the cutting element support member. The cutting element has a volume of superabrasive material on a first end of a substrate, and a lateral side surface extending from the first end of the substrate to an at least substantially planar back surface. The at least substantially planar back surface of the cylindrical substrate abuts an at least substantially planar support surface of the cutting element support member.

Abstract: A cutter element for rock removal comprises a free standing PCD body (801, 1801) comprising two or more physical volumes (1702, 1703) within the boundary of the PCD body, wherein adjacent physical volumes differ in one or more of diamond and metal network compositional ratio, metal elemental composition and diamond grain size distribution, a functional working volume (803) distal to the PCD body, the functional working volume forming in use a region which comes into contact with the rock. A functional support volume (804) extant in use and having a proximal free surface extends from the functional working volume. The PCD body has a shape having an aspect ratio such that the ratio of the length (ae) of the longest edge of the circumscribing rectangular parallelepiped of the overall PCD body to the largest width (ad) of the smallest rectangular face from which the functional working volume extends of the circumscribing rectangular parallelepiped, is greater than or equal to 1.

Abstract: A method of producing a drill bit, such as for drilling a well into an earth formation, includes forming a bit body having a plurality of blades. Each of the plurality of blades includes a forward facing face with respect to a direction of rotation of the bit. The forward facing face includes individual cutter pockets at least partially recessed into the forward facing face. The method also includes securing a cutting element at least partially within each of the individual cutter pockets. Each cutting element has an abrasion resistance. Each of the plurality of blades is formed of a blade material having an abrasion resistance that is less than the abrasion resistance of the cutting element.

Abstract: A drill bit matrix is provided that contains a powdered abrasive material and a refractory metal powder in which the refractory metal powder is a coated powder in which each granule of the refractory metal powder is coated by a coating material. A core drill bit is further provided, containing a powdered abrasive material, a refractory metal powder and a steel tube onto which the powdered abrasive material and refractory metal powder are alloyed. The refractory metal powder is a coated powder in which each granule of the refractory metal powder is coated by one or more coating materials. A method is finally provided for manufacturing a core drill bit. First a matrix is formed by mixing together a powdered abrasive material and a coated refractory metal powder. The matrix is placed in a mould and a steel tube is placed on top of the mould to form a drill bit assembly. The drill bit assembly is then heated under atmospheric conditions.

Abstract: A steel gear 1 includes a generally cylindrical outer peripheral ring portion 2, on an outer peripheral surface 20a of which a toothed shape 10 is formed, and a flange portion 3 provided to extend radially inward from an inner peripheral surface 20b of the outer peripheral ring portion 2. The outer peripheral ring portion 2 includes a first projecting portion 21 that projects toward one side in the axial direction with respect to a coupling position at which the first projecting portion 21 is coupled to the flange portion 3, and a second projecting portion 22 that projects toward the other side in the axial direction with respect to a coupling position at which the second projecting portion 22 is coupled to the flange portion 3. The axial length of the first projecting portion 21 is longer than the axial length of the second projecting portion 22.

Abstract: Earth-boring tools may have a body, a cutting element attached to the body at a first location, and a formation-engaging structure attached to the body at a second location. The formation-engaging structure may be movable during a drilling operation between a first position and a second position. In the first position, the formation-engaging structure may be located rotationally behind the cutting element at a first radial distance from a longitudinal axis of the body at which the cutting element will at least initially shield the formation-engaging structure from engaging a formation. In the second position, the formation-engaging structure may be located at a different second radial distance from the longitudinal axis of the body at which the formation-engaging structure will engage a formation.

Abstract: A steel gear includes a substantially cylindrical outer peripheral ring portion having a toothed shape formed on its outer peripheral surface; and a flange portion extended radially inward from an inner peripheral surface of the outer peripheral ring portion. The steel gear has a thermal history layer formed in the outer peripheral ring portion, and the depth of the thermal history layer in the direction inward from the tooth bottom of the toothed shape of the outer peripheral surface is greater in the first protruding portion and the second protruding portion than in the coupling portion with the flange portion, and is substantially the same between the first protruding portion and the second protruding portion. As a result, even if the “carburization/slow cooling/high-frequency quenching treatment” is used as a manufacturing method of the steel gear, the steel gear has high dimensional accuracy.

Abstract: Tips for pick tools and pick tools comprising same are provided. The tip comprises an impact structure formed joined at a non-planar boundary surface of a substrate. The boundary surface includes a depression. The impact structure comprises super-hard material and has a working end including an apex opposite the depression. The boundary surface of the substrate comprises a ridge at the periphery of the depression and a generally tapered circumferential region depending away from the ridge towards a side of the tip, a lowest point of the depression being directly opposite the apex.

Abstract: A drill bit may include a bit body including at least one blade extending at least partially over a cone region of the bit body. Additionally, the drill bit may include a plurality of cutting structures mounted to the at least one blade and a rubbing zone within the cone region of the at least one blade, wherein cutting structures within the rubbing zone have a reduced average exposure. Additionally, a method of directional drilling may include positioning a depth-of-cut controlling feature of a drill bit away from a formation to prevent substantial contact between the depth-of-cut controlling feature and rotating the drill bit off-center to form a substantially straight borehole segment. The method may also include positioning the depth-of-cut controlling feature of the drill bit into contact with the formation to control the depth-of-cut and rotating the drill bit on-center to form a substantially nonlinear borehole segment.

Abstract: A drill bit that includes a body having a lower end face for engaging a rock formation. The end face having a plurality of raised ribs extending from the face of the bit body and separated by a plurality of channels therebetween At least one of the plurality of ribs has a varying width along at least a portion of a rib height.

Abstract: A polycrystalline diamond cutting (PDC) element of a drill bit of a downhole drilling tool is provided. The PDC element having a substrate, a diamond table and at least one pattern. The diamond table has an initial cutting edge along a periphery thereof. The pattern integrally formed within the diamond table. The pattern(s) defining at least one discontinuity about the diamond table that, in operation, selectively breaks away upon impact to create new cutting edges in the diamond table whereby a sharp cutting edge is continuously exposed to a material being cut.

Abstract: Cutting elements for use with earth-boring tools include a cutting table having at least two sections where a boundary between the at least two sections is at least partially defined by a discontinuity formed in the cutting table. Earth-boring tools including a tool body and a plurality of cutting elements carried by the tool body. The cutting elements include a cutting table secured to a substrate. The cutting table includes a plurality of adjacent sections, each having a discrete cutting edge where at least one section is configured to be selectively detached from the substrate in order to substantially expose a cutting edge of an adjacent section. Methods for fabricating cutting elements for use with an earth-boring tool including forming a cutting table comprising a plurality of adjacent sections.

Abstract: Cutting elements for earth-boring tools may generate a shear lip at a wear scar thereon during cutting. A diamond table may exhibit a relatively high wear resistance, and an edge of the diamond table may be chamfered, the combination of which may result in the formation of a shear lip. Cutting elements may comprise multi-layer diamond tables that result in the formation of a shear lip during cutting. Earth-boring tools include such cutting elements. Methods of forming cutting elements may include selectively designing and configuring the cutting elements to form a shear lip. Methods of cutting a formation using an earth-boring tool include cutting the formation with a cutting element on the tool, and generating a shear lip at a wear scar on the cutting element. The cutting element may be configured such that the shear lip comprises diamond material of the cutting element.

Abstract: A method of optimizing drill bit design and an optimized drill bit for drilling a well into an earth formation comprising a bit body; a number of blades spaced around the bit body, each blade having a curved outer edge and a forward face; a first row of cutter pockets recessed into the face along the outer edge of each blade; a second group of cutter pockets recessed into the face of each blade offset from the first row; and a plurality of cutting elements, each cutting element being brazed into a different one of the cutter pockets.

Abstract: A bearing element for a rotary, earth boring drag bit effectively reduces an exposure of at least one adjacent cutting element by a readily predictable amount, as well as a depth-of-cut (DOC) of the cutter. The bearing element has a substantially uniform thickness across substantially an entire area thereof. The bearing element also limits the amount of unit force applied to a formation so that the formation does not fail. The bearing element may prevent damage to cutters associated therewith, as well as possibly limit problems associated with bit balling, motor stalling and related drilling difficulties. Bits including the bearing elements, molds for forming the bearing elements and portions of bodies of bits that carry the bearing elements, methods for designing and fabricating the bearing elements and bits including the same, and methods for drilling subterranean formations are also disclosed.

Abstract: A bearing element for a rotary, earth boring drag bit effectively reduces an exposure of at least one adjacent cutting element by a readily predictable amount, as well as a depth-of-cut (DOC) of the cutter. The bearing element has a substantially uniform thickness across substantially an entire area thereof. The bearing element also limits the amount of unit force applied to a formation so that the formation does not fail. The bearing element may prevent damage to cutters associated therewith, as well as possibly limit problems associated with bit balling, motor stalling and related drilling difficulties. Bits including the bearing elements, molds for forming the bearing elements and portions of bodies of bits that carry the bearing elements, methods for designing and fabricating the bearing elements and bits including the same, and methods for drilling subterranean formations are also disclosed.

Abstract: A drill bit has cutting elements with multiple cutting surface geometries that are positioned so that their cutting profiles overlap, but do not completely contain or engulf one another. The different cutting surface geometries and the specific overlap create a zone of high density in the middle regions of the cutting profiles and low density in the periphery, resulting in a cutting profile that becomes sharper with increasing wear. Such an arrangement is more effective and stable as the drill bit encounters hard and abrasive formation materials. Moreover, cutting elements with larger axial volumes may be combined with cutting elements having smaller axial volumes.

Abstract: A diamond impregnated drill bit features layered encapsulation of the diamond grit where the innermost layer is hardest or most abrasion resistant while succeeding layers are generally softer and less wear resistant. This can be accomplished by manipulating several variables in the encapsulation layers such as particle size or hard particle concentration. The outer layers can have added binder to make them softer. The encapsulated grit can be sintered or pre-sintered to make it less friable when handled. As a result the encapsulated diamonds are retained in the matrix longer with higher protrusion to improve bit longevity and penetration rates.

Abstract: A drill bit has cutting elements with multiple cutting surface geometries that are positioned so that their cutting profiles overlap, but do not completely contain or engulf one another. The different cutting surface geometries and the specific overlap create a zone of high density in the middle regions of the cutting profiles and low density in the periphery, resulting in a cutting profile that becomes sharper with increasing wear. Such an arrangement is more effective and stable as the drill bit encounters hard and abrasive formation materials. Moreover, cutting elements with larger axial volumes may be combined with cutting elements having smaller axial volumes, resulting in an even more effective drill bit in terms of durability and ability to drill efficiently in hard and abrasive formations.

Abstract: A tool insert comprises a substrate (10) having a support surface and a support ring extending laterally from the support surface. The support ring is sized to define a recess (14) within the confines thereof and a shelf about the periphery thereof. A layer (12) of ultra-hard abrasive material is located within the recess and bonded to the substrate and the support ring (16), and presents a primary cutting edge (22) for the tool insert. A protective layer (18) is bonded to the shelf about the support ring so as to protect the primary cutting edge. The protective layer provides a secondary cutting edge (20) for the tool insert, the depth of the protective layer being selected so as to be sufficient to protect the primary cutting edge whilst cutting, milling or drilling through a first substance but to expose the primary cutting edge upon encountering a second substance.

Abstract: Apparatus and methods for drilling with casing. In an embodiment, methods and apparatus for deflecting casing using a diverter apparatus are disclosed. In another embodiment, the apparatus comprises a motor operating system disposed in a motor system housing, a shaft operatively connected to the motor operating system, the shaft having a passageway, and a divert assembly disposed to direct fluid flow selectively to the motor operating system and the passageway in the shaft. In another aspect, methods and apparatus for directionally drilling a casing into the formation are disclosed. Methods and apparatus for measuring the trajectory of a wellbore while directionally drilling a casing into the formation are also described.

Abstract: A long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has a self-actuating mechanism responsive to the hardness of the geological formation to minimize the time necessary to drill a borehole. A long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has a mechanism controllable from the surface of the earth to change the mechanical configuration of the bit to minimize the time necessary to drill a borehole. A monolithic long lasting rotary drill bit for drilling a hole into a geological formation having hardened rods composed of hard material such as tungsten carbide that are cast into a relatively soft steel matrix material to make a rotary drill bit that compensates for wear on the bottom of the drill bit and that also compensates for lateral wear of the drill bit using passive, self-actuating mechanisms, triggered by bit wear to drill relatively constant diameter holes.

Abstract: Cutter elements including pointed contact structures and elements, and rock tools or bits for carrying those elements, for chipping, cutting, and breaking non-ductile materials are disclosed. The cutter elements, the ends of which directly contact and cut through rock and other materials, have tapered contact structure ends which are flatter than those known to the prior art, obtaining increased durability. The contact elements which may be part of the contact structures are selected of materials having hardness and other characteristics in relation to those of the mounting structures, including the tapered and projecting portions, which also add durability and wear-resistance to the elements. Fixed, replaceable, and rotatable cutter elements are disclosed. Rock tools including bits are also disclosed for carrying the cutter elements, having sockets for threaded or rotatable cutter elements arranged in straight or curved rows on the head opposite the drill-string-engaging base of the tool.

Abstract: A drill bit employing a plurality of discrete, post-like, abrasive, particulate-impregnated cutting structures extending upwardly from abrasive, particulate-impregnated blades defining a plurality of fluid passages therebetween on the bit face. Additional cutting elements may be placed in the cone of the bit surrounding the centerline thereof. 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. Additionally, discrete protrusions may extend outwardly from at least some of the plurality of cutting structures. The discrete protrusions may be formed of a thermally stable diamond product and may exhibit a generally triangular cross-sectional geometry relative to the direction of intended bit rotation.

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 present invention relates to providing a drill bit stabilizing system and methods which overcome the above noted problems. The at least one stabilizing member is biased to a second extended operating position. The body member further comprises at least one fixed stabilizing surface positioned in axially spaced relationship to the at least one movable stabilizing member. In another aspect, the invention is directed to a drill bit stabilizing system comprising a body member and at least one stabilizing member, being moveable from an extended operating position to a retracted position within the body member. The at least one stabilizing member comprises outer contact faces adapted to engage the walls of a bore hole when in an operating position, and an inner slide surface adapted to slidingly engage a corresponding slide surface formed in the body member. There is also provided a method of drilling a bore hole using a drill bit rotated in conjunction with a drill string.

Abstract: A long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has a self-actuating mechanism responsive to the hardness of the geological formation to minimize the time necessary to drill a borehole. A long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has a mechanism controllable from the surface of the earth to change the mechanical configuration of the bit to minimize the time necessary to drill a borehole. A monolithic long lasting rotary drill bit for drilling a hole into a geological formation having hardened rods composed of hard material such as tungsten carbide that are cast into a relatively soft steel matrix material to make a rotary drill bit that compensates for wear on the bottom of the drill bit and that also compensates for lateral wear of the drill bit using passive, self-actuating mechanisms, triggered by bit wear to drill relatively constant diameter holes.

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 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 dual function drag bit is used in a method for both milling well casing or liner and subsequently drilling rock formation without the sequential removal of a milling assembly and replacement with a drilling assembly. The method employs a cutting tool that is capable of both milling steel pipe casing in a well bore and subsequently drilling rock formation outside the well bore after passing through the casing. In one embodiment an insert embedded into the surface of the cutting tool comprises at least an outer layer, such as cemented tungsten carbide, capable of milling steel casing, and at least a second layer, such as polycrystalline diamond, capable of drilling formation, the two layers being bonded together and to a carbide substrate. In another embodiment, inserts with a polycrystalline diamond cutting face for drilling rock formation are in parallel with cemented tungsten carbide cutters for milling steel casing.

Abstract: The present invention provides a diamond impregnated bit with an adaptive matrix in the ribs. The ribs have at least two different areas of metal-matrix composite impregnated with diamonds with different wear resistance such that during boring of formation, the areas will wear at different rates and provide fluid flow spaces across the surface of the ribs.

Abstract: An abrasive tool for cutting extremely abrasive-resistant materials includes a novel, abrasive segment with a generally crenelated, rectangular appearance. The segment has a single piece vein of a primary abrasive and first bond material extending completely along the length of the segment. The vein transverses the width of the segment at least once in a non-linear path and alternately coincides with inner and outer faces. Gaps between the vein and the faces opposite the vein coincident faces are occupied by a second bond material, and optionally, a secondary abrasive, thus forming multiple, separated abrasive regions. The bottom surface of the segment is attached to a core at an operative perimeter which defines the cutting edge of the tool. The segment can be adapted to conform to the curvature of diverse cutting edges, and thus can be used in rotary and reciprocating saw blades and core drilling bits.

Abstract: A monolithic long lasting rotary drill bit for drilling a hole into a geological formation having at least one hardened rod which has a length of at least three times its diameter composed of hard material such as tungsten carbide that is cast into a relatively soft steel matrix material to make a rotary drill bit that compensates for wear on the bottom of the drill bit and that also compensates for lateral wear of the drill bit using passive, self-actuating mechanisms, triggered by bit wear to drill relatively constant diameter holes.

Abstract: Methods for making, methods for using and articles comprising cermets, preferably cemented carbides and more preferably tungsten carbide, having at least two regions exhibiting at least one property that differs are discussed. Preferably, the cermets further exhibit uniform or controlled wear to impart a self-sharpening character to an article. The multiple-region cermets are particularly useful in wear applications. The cermets are manufactured by juxtaposing and densifying at least two powder blends having different properties (e.g., differential carbide grain size or differential carbide chemistry or differential binder content or differential binder chemistry or any combination of the preceding).

Abstract: Methods for making, methods for using and articles comprising cermets, preferably cemented carbides and more preferably tungsten carbide, having at least two regions exhibiting at least one property that differs are discussed. Preferably, the cermets further exhibit uniform or controlled wear to impart a self-sharpening character to an article. The multiple-region cermets are particularly useful in wear applications. The cermets are manufactured by juxtaposing and densifying at least two powder blends having different properties (e.g., differential carbide grain size or differential carbide chemistry or differential binder content or differential binder chemistry or any combination of the preceding).

Abstract: A monolithic long lasting rotary drill bit for drilling a hole into a geological formation having at least one hardened rod which has a length of at least three times its diameter composed of hard material such as tungsten carbide that is cast into a relatively soft steel matrix material to make a rotary drill bit that compensates for wear on the bottom of the drill bit and that also compensates for lateral wear of the drill bit using passive, self-actuating mechanisms, triggered by bit wear to drill relatively constant diameter holes.

Abstract: Self-shaping disk-shaped cutting edge of a drilling tool, comprising an outer diamond-impregnated polycrystalline layer (22) applied onto a tungsten carbide layer (24), each cutting edge being mounted on a support (18) which is integral with the body (12) of the drilling tool. The cutting edge and/or its support (18) have areas (26) of least resistance, such as grooves, which are likely to cause successive fractures, thereby forming an acute relief angle (.alpha.) with the rock to be drilled (28).

Abstract: A preform cutting element for a rotary drill bit for use in drilling or coring holes in subsurface formations includes a cutting table 12, 13 of superhard material such as polycrystalline diamond. The rear face of the cutting table is bonded to a substrate 11 of less hard material, such as cemented tungsten carbide. A front portion 12 of the cutting table comprises a form of superhard material which is less wear-resistant than the superhard material forming the remainder 13 of the cutting table. The provision of the less wear-resistant superhard material at the front cutting faces reduces the tendency of the cutting table to spall.

Abstract: The present invention comprises a rotary drill bit including a cutting structure comprising an array of cutting elements oriented and arranged to facilitate concentration of the load on bit on groups of cutting elements until the elements become dulled or worn, at which point fresh cutting elements are exposed to engage the formation and tube the concentrated bit loading. Preferably, the cutting elements are configured and/or supported to break away from the cutting structure when worn to a certain extent, thereby facilitating exposure of fresh cutting elements to engage the formation.

Abstract: A blade (8) for a pipe milling tool having a body (1) and a longitudinal axis (100) has a plurality of slots (12) extending both in a generally radial direction and in an intended direction of rotation of the milling tool about the longitudinal axis. Located in each slot (12) is at least one cutting element (13), the slot and the cutting element both having a greater depth in the blade in the intended direction of rotation than height in the longitudinal axis direction. The provision of such dimensions for the slot and cutting element affords the blade with improved life. The cutting elements may each have a negative axial rake angle (A) and the cutting elements are preferably brazed in each of the slots. In a preferred embodiment the slots and the cutting elements are both similarly decreasingly tapered from a forward (leading) face (221) to a rearward face (218) with respect to the intended direction of rotation of the tool by an angle in the range 1.degree. to 20.degree..

Abstract: A cutting structure for a rotary drill bit includes a cutting element 30 having a front layer 32 formed of polycrystalline diamond, bonded to a backing layer 33 formed of tungsten carbide. The cutting element is bonded to a carrier 33 which is formed of a number of detachable individual elements having means holding them in position such that, upon wear of the cutting structure in use, the holding means of an element engaging the formation will eventually fail, causing detachment of that element from the carrier, and thereby reducing the area of the cutting structure in contact with the formation.

Abstract: A fishtail type drag bit having abradable cutter blades attached to a body of the bit is disclosed. A multiplicity of axially aligned tubes are welded together to form a blade each blade being sustantially parallel with an axis of the bit body. Each tube of the blade contains an annulus of a diamond cutter material matrix. The center of the annulus forms a fluid conduit that communicates with a fluid plenum chamber formed by the body of the bit. The cutting edge of the diamond matrix therefore, is always immediately adjacent the fluid nozzle regardless of the degree of blade erosion during operation of the bit in a subterranean formation.

Abstract: A rotary drill bit, for drilling wells in subsurface earth formations, and designed for rotation in a given direction, comprises a bit body having an internal passageway for drilling fluid. The bit body has an operating end face and at least one opening through that face communicating with the passageway. Cutters on the bit body form at least one elongate cutting region extending generally radially along a substantial portion of the operating end face. The cutters have cutting surfaces facing in the forward direction and generally continuous cutting edges at the outer extremity of the cutting surfaces. An elongate fence is carried on the bit body, extending generally parallel to the cutting region and spaced from the cutting region in a leading direction.

Abstract: Drag-type drilling bits are disclosed which have at least one blade and a plurality of fluid flow channels incorporated in the blade for conducting drilling fluid or drilling mud from the hollow interior of the bit to discharge or ejection ports located in the front cutting edge of the blade. Rods of diamonds or of like "hard" cutter insert materials are incorporated in the blade in such a configuration that as the blade wears away or erodes and small pieces of diamonds are lost during drilling, more diamonds are exposed to the formation for drilling. During erosion or wear of the blades, the fluid discharge ports continue to operate to eject drilling fluid adjacent to substantially each diamond rod, whereby the flushing away of cuttings and cooling of the diamonds is greatly improved. In some embodiments of the invention rods of alternating hard and soft materials are also disposed substantially parallel with the diamond or like "hard" cutter insert rods.