Abstract: A female portion arranged to form part of a thread joint for a percussive drilling tool includes a mounting sleeve, wherein the mounting sleeve has at least one substantially cylindrical internally threaded section having a length, L1, a thread entrance located towards an axial end and a thread exit located towards the axial inner wall. The threaded section has a thread form including crests, roots, contact flanks, and non-contact flanks, a pitch length, L4, located between two axially neighboring crests and an inner diameter, D2 disposed radially between the roots. A thread clearance section is positioned between the axial inner wall and the thread exit and has a length L2 and a diameter D1. A guiding section is positioned between the thread entrance and the axial end of the sleeve and has a length, L3. The pitch length, L4, is between 12.8-14.5 mm.

Abstract: A connection for use in percussion drilling includes a male coupling and a female coupling. Each coupling includes a body and a respective screw thread formed on a respective inner or outer surface of the respective body. Each thread has a thread-form including a crest, a root, a contact flank and a non-contact flank. Each thread-form has a contact flank angle and a non-contact flank angle inclined relative to a respective baseline located at a respective minor or major diameter thereof. Each non-contact flank angle is greater than the respective contact flank angle. The crest of each thread-form is inclined from the respective contact flank to the respective non-contact flank such that an apex of the respective thread-form defining a respective minor or major diameter thereof is located adjacent to the respective non-contact flank.

Abstract: A rotation indication device for a rock bolt including a central rod with a threaded trailing portion. The rotation indication device includes a blind nut having a threaded central recess for engaging the threaded trailing portion and a visual indication means provided at a bottom portion of the central recess and configured such that upon movement of the threaded trailing portion of the central rod into the bottom portion of the central recess, the central rod forces at least a portion of the visual indication means to move through a passage in the blind nut between the bottom portion of the central recess and the outside of the blind nut.

Abstract: A drill string rod is arranged to form part of an assembly of connected drill string rods. The drill string rod includes an elongate central rod portion extending axially between a male and female end. The central rod portion is a hollow-cylindrical defined by an inner first diameter (drod) and an outer second diameter (Drod). The male end includes a spigot having a base projecting axially from a shoulder that axially separates the spigot and the central rod portion. The female end includes a sleeve portion configured to fit to the spigot. The base has an outer thread and the sleeve portion has an inner thread, the inner thread corresponding to the outer thread such that the inner thread of the sleeve portion is attachable to the outer thread of the base of the spigot of a further drill string rod of the assembly.

Abstract: A drilling assembly for percussive drilling includes at least two of a drill bit, a drill rod and a guide adapter. A peripheral surface of the shoulder on the drill rod is at least partially encased in both radial and axial directions inside the mounting sleeve of the drill bit or the mounting sleeve of the guide adapter, and/or the peripheral surface of the shoulder on the guide adapter is at least partially encased in both radial and axial directions inside the mounting sleeve of the drill bit.

Abstract: A rock drill insert made of cemented carbide includes hard constituents of tungsten carbide (WC) in a binder phase of Ni—Cr, or Ni—Co—Cr, and a balance of WC and unavoidable impurities. The cemented carbide has a 3.5-18 wt % binder phase. The binder phase has >0 wt % Ni. The mass ratio Cr/(Ni+Co) is 0.02-0.19. A difference between the hardness at 0.3 mm depth at some point of the surface of the rock drill insert and the minimum hardness of the bulk of the rock drill insert is at least 30 HV3.

Abstract: A drill string including an elongate hollow main length section and a male spigot portion provided at the second end and having an externally threaded section and a non-threaded shank positioned axially intermediate the main length section and the threaded section. The shank includes a transition section positioned adjacent the main length section or a radially projecting shoulder at the second end. The transition section has an outside diameter that increases in a direction from the male spigot portion to the main length section or the shoulder. The cross-sectional shape profile of the outer surface of the transition section in the plane of the longitudinal axis has a segment of an ellipse having semi-major axis (a) and a semi-minor axis (b), wherein the ratio of the semi-major to semi-minor axes (a:b) is within the range 2b<a<8b.

Abstract: A roller cutter for a drill head for raise boring. The roller cutter having a shaft with a longitudinal center line, a hub rotatably mounted on the shaft, and a seal retainer located between the axial ends of the hub and the shaft at least arranged at one end of the roller cutter. The seal retainer supports a primary cutter seal providing sealing between the shaft and the hub in both axial and radial directions. A secondary cutter seal is located between the seal retainer and the hub, such that the secondary cutter seal provides sealing in the axial direction.

Abstract: A down-the-hole drilling assembly activated by fluid under pressure includes a casing having an axially rearward and forward end, a piston arranged movably inside the casing, a plurality of fluid passages for feeding and discharging pressurized fluid into and out of a working chamber for generating reciprocating movement of the piston, a drill bit at the forward end and provided with an anvil facing towards the piston for receiving impacts therefrom and an annular drive sub surrounding at least a portion of a shank and cooperating with the bit to form fluid passages extending length-wise along the shank. The drive sub has a concave arcuate groove extending circumferentially to form a chamber for collecting fluid from the hammer exhaust and redistributing a volume of the collected fluid from channels formed between complimentary splines of the drive sub and splines of the bit to flushing holes arranged in the bit.

Abstract: A drill bit for percussion drilling includes a drill bit body including a front surface. The front surface includes a first circular area arranged transverse and coaxially to the axis of the drill body, a second area surface surrounding the first area surface, and a third area surface surrounding the second area surface. A number of buttons are arranged in the second and third area surfaces. The button body of each button has a forward end surface. The buttons are arranged in circular recesses extending substantially transverse from the second surface and third area surface into the drill bit body. The recesses have a radius corresponding to the button body radius and a depth corresponding to the length of the button body, such that the button bodies are fitted within the drill bit body with the forward end surface exposed in the second and third area surfaces.

Abstract: A disc cutter for a cutting unit used in an undercutting operation and a method of producing the same. The disc cutter including an annular disc body made of a metal alloy or metal matrix composite having a first side, a second side arranged substantially opposite to the first side and a radially peripheral part. At least one metal alloy, metal matrix composite or cemented carbide cutting part is mounted in and substantially encircling the radially peripheral part of the disc body which protrudes outwardly therefrom to engage with the rock during the mining operation. The at least one cutting part is made from a material having a higher wear resistance than the material used for the disc body, wherein the disc body and the cutting part are joined by diffusion bonds.

Abstract: A rock bolt for installation within a bore formed in rock strata having an elongate shaft with the leading end for installation into the bore and a trailing end projecting from an open end of the bore. A locking nut is threadably attached to the trailing end and is arranged to display product information and the like at a display face. The display face is recessed axially into the nut to provide protection against damage to the display face that may otherwise render the information unreadable.

Abstract: A method of treating a sintered mining insert including cemented carbide includes the step of subjecting the mining insert to a surface hardening process. The surface hardening process is executed at an elevated temperature of or above 100° C. A mining insert is also provided, wherein the HV1 Vickers hardness measurement increase (HV1%) from the surface region, measured as an average of HV1 measurements taken at 100 ?m, 200 ?m and 300 ?m below the surface, compared to the HV1 Vickers hardness measured in the bulk (HV1bulk), is at least 8.05-0.00350×HV1bulk.

Abstract: A drill string rod includes an elongate central rod portion. The central rod portion has a hollow-cylindrical shape with an inner first diameter (drod) and an outer second diameter (Drod). The male end includes a spigot having a base projecting axially from a shoulder that axially separates the spigot and the central rod portion. The female end has a sleeve portion that fits to the spigot. An inner thread of the sleeve portion is attachable to an outer thread of the base of the spigot of a further drill string rod. In a radial plane to the longitudinal axis of the drill string rod, the base of the spigot is defined by an outer third diameter (Dspigot) and an inner fourth diameter (dspigot) and the sleeve portion is defined by an outer fifth diameter (Dsleeve) and an inner sixth diameter (dsleeve), wherein the second diameter (Drod) is >60 mm.

Abstract: A coupling for connecting downhole tubulars includes a tubular body, and at least one thread of a male screw thread formed on an outer surface of the body, and a female screw thread formed in an inner surface of the body. The at least one thread has a thread-form including a crest, a root, and a pair of flanks. The crest and the root are each cambered about a respective first and second camber radius. Each camber radius is greater than an outer diameter of the coupling.