Abstract: A tool component is provided which has particular application in mining picks and drag bits. The component comprises an abrasive compact having a flat working surface presenting a cutting edge around its periphery, and an opposite surface bonded to a cemented carbide substrate along an interface. A recess is provided which extends into the abrasive compact from the interface and is filled with abrasive compact. The recess has a central portion and an outer portion which completely surrounds, and is shallower than the central portion. The central portion defines, in plan, at least one substantially wedge-shaped configuration, the configuration having a narrow end coincident with a side surface of the component and the sides extending into the component and diverging from the narrow end.

Abstract: A method of making a bonded, coherent material comprising a mass of diamond crystals in a matrix, which optionally contains another phase. The method includes the steps of providing a source of diamond crystals, providing a plurality of diamond centers defined by diamond crystals, producing a reaction mass by bringing the source and growth centers into contact with a solvent/catalyst, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth in the reaction zone of a high temperature/high pressure apparatus to produce the material, and removing the material from the reaction zone. The method is characterized by providing the necessary supersaturation of carbon in the solvent/catalyst, at least in part and preferably predominantly, by a selection of particle size difference between the source crystal and the growth centers. The mass of diamond crystals in the matrix of the bonded, coherent material of the invention has a high concentration of twinned diamonds.

Abstract: A method of making a drill blank which is elongate and which has a vein of a bonding material located in an end surface thereof. A recess is formed in a surface of a cemented carbide body. Either a layer of ultra-hard abrasive or a mass of ultra-hard abrasive particles is then placed on a surface of the recess. A cemented carbide piece, having the same shape and cross-sectional size as the recess, is inserted into the recess. The cemented carbide body is subjected to conditions of elevated temperature and pressure so that either the abrasive compact layer or the layer of the ultra-hard abrasive bonds the cemented carbide piece to the cemented carbide body. Finally, the cemented carbide body is severed through either the abrasive compact layer or layer of ultra-hard abrasive to produce one or more drill blanks.

Abstract: A drill blank, particularly a blank for a micro-drill, comprises an elongate cylindrical cemented carbide body, having flat end surfaces, a recess formed in one end surface and taking the form of an island in that surface wholly surrounded by cemented carbide, and an abrasive compact located in the recess, bonded to a cemented carbide, and presenting a surface coincident with the carbide end surface in which the recess is located. A drill may be formed from the drill blank by suitably shaping the cemented carbide body, for example, by fluting, in the region of the abrasive compact to expose the abrasive compact.

Abstract: The invention concerns a cutter pick mounting apparatus which is used to mount a cutter pick (10) to a pick box (12) which is secured to the drum of a mining machine. The cutter pick has a pick body (14) having a base (25) of circular cross-section and a shank (26) of smaller circular cross-section extending from the base. The shank is eccentric with respect to the base. The pick box is formed with a countersunk socket (30) that has a base-receiving recess (32) and a shank-receiving bore (34) which extends from the base of the recess. The bore is eccentric with respect to the recess, the eccentricity (38) corresponding to the eccentricity (28) of the shank of the pick body with respect to the base of the pick body. With this configuration the pick body (14) can be held non-rotatably in the socket (30) with the base locating complementally in the recess and the shank locating complementally in the bore.

Abstract: A tool component comprises abrasive compact, typically a diamond abrasive compact, having a flat working surface which presents a cutting edge and an opposite surface bonded to a surface of a cemented carbide substrate to define an interface having at least two steps. The steps extend from one surface of the component to another surface and the interface is spaced from the working surface at one of the component surfaces a greater distance than at the other component surface. The tool component has particular application as a cutting insert for a rotatable cutter of an earth boring bit.

Abstract: A diamond-bearing assembly comprises opposed diamond-bearing surfaces, at least one of which is free of any Group VIII metals such as cobalt. Preferably, each of the surfaces is provided by a surface of a diamond compact, such diamond compact containing substantial diamond-to-diamond bonding, and a second phase which contains silicon in the form of silicon and/or silicon carbide.

Abstract: A method of producing an abrasive compact, particularly a diamond abrasive compact, is provided. The method uses conventional compact manufacture conditions and is characterized by the mass of abrasive particles which is used. This mass has an average particle size of less than 20 and consists of particles having at least three different average particle sizes.

Abstract: A composite diamond abrasive compact comprises a diamond compact bonded to a cemented carbide support along a compact/carbide interface and is characterised by the carbide support comprising at least two zones, a first zone containing a binder metal content of a predetermined amount, and a second zone extending from the interface to the first zone and having a binder metal content which is substantially lower than that of the first zone. The second zone has a depth or thickness of no more than 0,75 mm. The binder metal content of the second zone increases from the interface to the first zone in a continuous, non-interrupted manner.

Abstract: A method of brazing a first body to a second body having particular application to the bonding of a composite abrasive compact to a substrate. The method involves the steps of providing a brazing shim comprising at least two zones having differing melting temperatures, placing the shim on a surface of the first body, placing a surface of the second body on the shim to form an unbonded assembly, applying heat to the assembly to cause the shim to melt and allowing the assembly to cool to a temperature at which all the zones of the shim become solid.

Abstract: A tool component comprises an abrasive compact layer bonded to a cemented carbide substrate along an interface. The abrasive compact layer has a working surface, on a side opposite to the interface. This working surface is flat and presents a cutting edge or point around its periphery. A recess extends into the substrate from the interface. The recess has a side wall and a base both of which are located entirely within the carbide substrate. The recess has a portion located in the interface. The area of this portion is at least 25 percent the area of the interface. A material, different to that of the substrate, fills the recess and is bonded to the substrate. This material will typically be abrasive compact of the same type as the abrasive compact layer, or a cemented carbide which has characteristics different to that of the substrate.

Abstract: The invention provides a method of making an abrasive compact using conventional compact synthesis conditions. The method is characterized by the use of an ultra-hard abrasive particle mass comprising at least 25 percent by mass of ultra-hard abrasive particles having an average particle size in the range 10 to 100 microns, and consisting of particles having at least three different average particle sizes, and at least 4 percent by mass of ultra-hard abrasive particles having an average particle size of less than 10 microns. The abrasive compact is preferably a diamond compact.

Abstract: The wire saw including a rope, abrasive beads spaced longitudinally apart on the rope by elastic spacers and elastic sleeves, one for each bead, sandwiched between the respective beads and the rope. The sleeves are conveniently made of rubber which is vulconized to the rope and to the beads.

Abstract: A tool insert comprising an abrasive compact layer having a working surface and an opposite surface bonded to a cemented carbide substrate along an interface. At least one cemented carbide projection extends through the compact layer from the compact/substrate interface to the working surface in which it presents a matching surface. The total area of the carbide matching surface is less than that of the compact working surface. The cemented carbide projection may take the form of one or more islands, or the form of a skeleton enclosing within it a plurality of discrete abrasive compact zones or sections.

Abstract: The invention concerns a diamond bearing assembly for a downhole motor. The assembly (10) includes at least one set of opposing, relatively rotating thrust bearing rings (20, 22) each of which includes an annular support element (24, 30) and PCD compacts (26, 32) carried by the support elements. The PCD compacts of the bearing rings oppose one another at a thrust bearing interface (80). Shear limiting means (96, 110) are provided. These means are arranged to shear if frictional forces between the opposing PCD compacts at the thrust bearing interface exceed a critical level. This eliminates relative rotation between the bearing rings and avoids possible overheating and thermal degradation of the PCD. The shear limiting means can also serve as an alignment means to ensure correct axial alignment of the bearing components. The bearing assembly may also include a compact radial bearing capability.

Abstract: The invention concerns a diamond thrust bearing assembly for a downhole motor. The assembly (10) includes at least one set of opposing bearing rings (20, 22), each of which has an annular support element (24, 30) and a plurality of PCD compacts (48, 62) carried in circumferentially spaced relationship by the support element. The PCD compacts present opposing bearing surfaces (52, 66) with the bearing surfaces (66) of the compacts of one bearing ring in each set being circumferentially longer than the bearing surfaces (52) of the compacts of the other bearing ring of the set.

Abstract: A cutting insert for a rotary cutting tool comprises a body of tungsten carbide, with layers of polycrystalline diamond on opposite sides of the body. The diamond layers overlap across the centre-line of the insert. The cutting insert is shaped for retention at the end of the rotary cutting tool so that the first and second sides of the cutting insert are substantially parallel to the axis of the cutting tool, and the diamond layers are offset from one another across the width of the body so that they define the lips or major cutting edges of the cutting tool.

Abstract: A method of producing a composite diamond abrasive compact includes the steps of forming an unbonded assembly comprising a cemented carbide body, a layer of catalyst metal on a surface of the carbide body, a layer of carbide particles, alone or in admixture with other particles, on the catalyst metal layer, and a layer of diamond particles on the carbide layer and subjecting the unbonded assembly to conditions of elevated temperature and pressure at which diamond is crystallographically stable to form a composite diamond abrasive compact.

Abstract: A cutting insert for a rotary cutting tool comprises a body of tungsten carbide, with layers of polycrystalline diamond on opposite sides of the body. The diamond layers overlap across the centre-line of the insert. The cutting insert is shaped for retention at the end of the rotary cutting tool so that the first and second sides of the cutting insert are substantially parallel to the axis of the cutting tool, and the diamond layers are offset from one another across the width of the body so that they define the lips or major cutting edges of the cutting tool.

Abstract: A method of producing a composite abrasive compact is provided. The method includes the steps of providing a cemented carbide substrate having two layers separated by a metallic layer. The metal of the metallic layer may be a ductile metal such as cobalt or nickel or a refractory, carbide-forming metal such as molybdenum, tantalum, niobium, hafnium, titanium or zirconium. A layer of the components, in particulate form, necessary to produce an abrasive compact is placed in a recess of the one layer to produce an unbonded assembly. The unbonded assembly is then subjected to suitable conditions of elevated temperature and pressure to produce an abrasive compact from the components.