Abstract: A drilling and chiseling bit includes a base member (1) having an axis extending in the drilling and chiseling direction. The base member has an end face disposed transversely of the axis, with a recess (3) extending in the axially direction inwardly from the end face. A cutting member (2) is secured in the recess by a soldered joint. At least one of the base member and cutting member is formed to prevent the development of shear stress peaks in the end regions of the recess extending transversely of the axial direction. To prevent the shear stress peaks, relief notches or recesses can be provided in the base member (1) or the soldered joint (4) can have a variable thickness in the axial direction increasing towards the opposite ends of the recess.

Abstract: A carbide mineral cutting tip (5) comprises a solid carbide body having at least one front face (6), at least one top face (9), a bottom, seating face (12), a rear face (20), and side faces (13), the rear face (20) being provided at the end of an extended tail portion (15) of the tip (5), whereby the front- to-rear length (A to C) of the tip (5) approximates to twice the depth of the tip (5) represented by the top-to-bottom length (D to E) of the front face (6). The invention also includes a mineral cutter pick (1) provided with such a tip.

Abstract: A drill for cutting holes in mine roofs comprises a shank and a wedge shaped carbide cutting insert frictionally clamped within a wedge-shaped slot formed in the front end of the shank. The insert and slot include a tongue-and-recess connection which radially centers the insert within the slot.

Abstract: A roller cutter rock bit includes a cutter constructed with a relief adjacent the cutter heel and gage inserts which each include elongated gage and bottom hole cutting edges which are separated from each other by an obtuse included angle. The edges serve to cut both the bottom of the borehole and the wall when changing the direction of drilling. Both the gage cutting edge and the bottom cutting edge of each gage insert are shaped so as to aggressively cut formation material.

Abstract: A rotary drill bit insert including an elongated body rotatable about a central axis and having two halves symmetrical about the axis, each symmetrical half having a top surface including a planar front surface contiguous a noncoplanar back relief surface, a bottom surface opposite the top surface, a leading face extending between forwardly facing edges of the front surface and the bottom surface, a trailing face opposite the leading face extending between rearwardly facing edges of the back relief surface and the bottom surface and a distal end surface extending between outwardly distal edges of the top surface, leading face, trailing face, and bottom surface.

Abstract: A rotary drill bit comprises a bit body carrying a plurality of preform cutting elements, and a plurality of circumferentially spaced gauge pads which, in use, engage the surrounding formation. Some of the gauge pads carry cutting elements and others are free of cutting elements. To reduce cost, each gauge pad which is free of cutting elements has an outer bearing surface which is more abrasion resistant than the outer surfaces of the gauge pads which carry cutting elements.

Abstract: A method is provided which bonds a composite abrasive compact to a cemented carbide pin. The method includes the steps locating a braze alloy having a perforated metal material embedded therein between a surface of the composite abrasive compact and a surface of the cemented carbide pin. The braze alloy has a melting point below that of the metal material. The surfaces are urged together, the temperature of the braze alloy is raised to above its melting point and maintained at this temperature for a short period. The alloy is then allowed to cool and solidify and bond the surfaces together.

Abstract: Cemented tungsten carbide rock bit inserts have diamond particles dispersed therein for enhanced hardness and wear resistance. The cobalt matrix is primarily the face centered cubic crystal structure for enhanced ductility and toughness. Such inserts are formed by introducing excess non-diamond carbon beyond the stoichiometric proportion in the tungsten carbide. The inserts are pressed at a temperature and pressure where diamond is thermodynamically stable and cooled while maintaining the pressure sufficiently high to prevent decomposition of diamond crystals formed at the elevated temperature. Diamond crystals may be dispersed throughout the cemented tungsten carbon or may be more concentrated near the surface than in the interior.

Abstract: An improved rotary rock bit having a circumferential row of wear resistant inserts protruding from the gage surface of each rolling cone cutter. The inserts are designed to efficiently break and remove earth formations. Adequate clearance is provided around the gage inserts for chip formation, chip removal, and insert cooling. These rows of inserts provide reaming action to maintain borehole gage diameter after the primary gage cutting structure has worn or failed.

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: A cutting element for a rotary drill bit comprises a thin superhard table of polycrystalline diamond material, defining a front cutting face, bonded to a less hard substrate. The substrate is formed from a material containing at least a proportion of tungsten metal. The substrate may be formed of a metal matrix composite comprising tungsten metal particles in a metal binder phase comprising material selected from: Cu, Co, Ni+Cu, Ni+Fe, Ni+Fe+Mo, Co+Ni. The substrate may also include tungsten carbide in which case the tungsten metal may be replaced by another softer refractory material.

Abstract: A rotary drill bit for boring earth formations is provided which includes a main body portion of a hard metal matrix material and at least one protrusion or shoulder formed of the same matrix material. On the protrusion is mounted a cutting element. Means for reinforcing the protrusion are provided and extend between the main body portion of the bit and the protrusion. The reinforcements add impact strength to the bit and increase the resistance of the bit to cracking in areas supporting the cutting element.

Abstract: A rotary drill bit comprises a bit body having a shank for connection to a drill string and a passage for supplying drilling fluid to the face of the bit, which carries a plurality of polycrystalline diamond preform cutting elements. In order to reduce bit whirl, the cutting elements are so disposed as to apply a resultant lateral imbalance force to the bit as it rotates during drilling and the gauge of the bit body is provided with low friction bearing pads to transmit said resultant lateral force to the sides of the borehole. Each low friction bearing pad includes an outwardly facing cavity which is connected to the passage by a choked conduit so that, in use, drilling fluid under pressure is delivered to the cavity, which thereby acts as a low friction hydrostatic bearing surface.