Drill string rod

Abstract

A drill string rod (1) to form part of an assembly (10) of connected such drill string rods (1, 1b), the drill string rod (1) comprising: an elongate central rod portion (2) extending axially between a male end (3) and a female end (4), wherein the central rod portion (2) is hollow-cylindrical defined by an inner first diameter (drod) and an outer second diameter (Drod), wherein the male end (3) comprises a spigot (5),wherein the spigot (5) comprises a base (6) projecting axially from a shoulder (7) that axially separates the spigot (5) and the central rod portion (2), wherein the female end (4) comprises a sleeve portion (8) configured to fit to the spigot (5), wherein the base (6) is provided with an outer thread and wherein the sleeve portion (8) is provided with an inner thread, wherein the inner thread corresponds to the outer thread such that the inner thread of the sleeve portion (8) is attachable to the outer thread of the base (6) of the spigot (5) of a further drill string rod (1b) of the assembly (10), wherein, in a radial plane (P) to the longitudinal axis (9) of the drill string rod (1), the base (6) of the spigot (5) is defined by an outer third diameter (Dspigot) and an inner fourth diameter (dspigot) and the sleeve portion (8) is defined by an outer fifth diameter (Dsleeve) and an inner sixth diameter (dsleeve), wherein the second diameter (Drod) is > 60 mm, and wherein the six diameters mentioned are selected within specific constraints.

Description

technical field [0001] The present invention relates to drill string rods for use with drill bits for percussion rock drilling. In particular, the present invention relates to improving the reliability and durability of such drill string rods. Background technique [0002] Percussion drilling is used to create long holes via a plurality of elongated drill string rods coupled together end-to-end by interconnecting male and female threaded ends. Well-established technology breaks rock by hammering impacts transmitted from a rock drill bit mounted at one end of the drill string to the rock at the bottom of the hole. Typically, the energy required to break the rock is generated by a hydraulically driven piston that contacts the end of the drill string (via the shank adapter) to generate a pressure (or shock) surge that travels through the drill string. the drill string and eventually propagates to the rock. Conventional couplings of male and female threads are described in US...

AI Technical Summary

Problems solved by technology

Conventional drill string rods are too weak to carry larger drill bits, and it has been shown that conventional drill string rods that are only enlarged in size are not an option because they tend to break in the casing or in the sleeve section, whereas Not approved for use until the threads of the sleeve / sleeve part are worn away

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