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 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 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 guide adapter for guiding a drill bit during percussion drilling is arranged between the drill bit and an elongated drill string extending along an axis. The guide adapter includes a sleeve shaped adapter body including a forward end with a first coupling arranged for connecting the guide adapter to the drill bit, and a rear end with a second coupling arranged for connecting the guide adapter to the drill string. A plurality of guiding elements extend substantially radially in relation to the axis from the adapter body. The guiding elements extend along 60% or less of the adapter body length and are arranged in the rear end. The guiding elements in the rear end have an extension in the radial direction substantially equal to a first radius of the drill bit and curved, straight or stepwise reduced radial extension towards the forward end.

Abstract: An elongate component, such as a drill rod or adaptor, forms part of a drill string having a shoulder contact male spigot coupling. The male spigot includes a non-threaded shank and a threaded section in which an axial length of the non-threaded shank is provided at a predetermined minimum relative to an outside diameter of the spigot at the threaded section.

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 threaded coupling for a drill string component includes a body on which is formed a thread. A reduction in stress concentrations and a resistance to bending moments are achieved at the thread by reducing a thread depth at at least one axial end of the thread and by arranging an endmost flank of a crest or root of the thread at an endmost helical turn.

Abstract: An elongate component, such as a drill rod or adaptor, forms part of a drill string having a shoulder contact male spigot coupling. The male spigot includes a non-threaded shank and a threaded section in which an axial length of the non-threaded shank is provided at a predetermined minimum relative to an outside diameter of the spigot at the threaded section.

Abstract: A threaded coupling for a drill string component includes a body on which is formed a thread. A reduction in stress concentrations and a resistance to bending moments are achieved at the thread by reducing a thread depth at at least one axial end of the thread and by arranging an endmost flank of a crest or root of the thread at an endmost helical turn.