Guide tube of a drill string configured to facilitate unscrewing thereof from a member of the drill string
AssigneeSandvik AB
InventorsKenneth Larsson, Gösta Reuter
Life of this patent
Estimating the term…
Abstract
A guide tube for use in a rock drill string includes a main portion, a sleeve disposed at a first end of the main portion, and a male thread portion disposed at a second end of the main portion. The sleeve forms a recess having a female thread. A flush channel extends through the guide tube. The main portion includes a section of reduced cross-section disposed adjacent the sleeve for defining a generally radially extending shoulder between the waist and the sleeve. The shoulder serves to support the guide tube on a rig as percussion is applied to the guide tube for loosening a threaded joint between the guide tube and another member.
Claims12
A guide tube adapted for use in a percussive rock drill string, the guide tube comprising:
- a main portion;
- a sleeve disposed at a first end of the main portion, the sleeve including a recess having a female screw thread formed therein;
- and
- a male thread portion disposed at a second end of the main portion, a flush channel extending completely through the main portion and the male thread portion and communicating with the recess, the recess having a first length extending along a longitudinal axis of the guide tube;
- the main portion including a section of reduced cross-section disposed adjacent the first end for defining a waist of narrower cross section than a maximum cross section of the sleeve, the waist having a second length extending along the axis which is longer than the length of the recess and shorter than a third length of the rest of the main portion,
- wherein a wall thickness of the waist is no less than a maximum wall thickness of the sleeve.
A drill string for percussive rock drilling;
- comprising a drill bit, a guide tube connected to the drill bit, an extension rod connected to the guide tube, and a shank adapter connected to the extension rod;
- the guide rod comprising:
- a main portion;
- a sleeve disposed at a first end of the main portion, the sleeve forming a recess having a female screw thread formed therein;
- and
- a male thread portion disposed at a second end of the main portion and threadedly attached to the drill bit, a flush channel extending completely through the main portion and the male thread portion and communicating with the recess, the recess having a first length extending along a longitudinal axis of the guide tube;
- the main portion including a section of reduced cross-section disposed adjacent the first end for defining a waist of narrower cross section than a maximum cross section of the sleeve, the waist having a second length extending along the axis and being longer than the length of the recess and shorter than a third length of the rest of the main portion,
- wherein a wall thickness of the waist is no less than a maximum wall thickness of the sleeve.
A method of unscrewing a threaded joint between a member and a guide tube of a drill string, the guide tube comprising:
- a main portion;
- a sleeve disposed at a first end of the main portion, the sleeve forming a recess having a female screw thread formed therein;
- and
- a male thread portion disposed at a second end of the main portion, a flush channel extending completely through the main portion and the male thread portion and communicating with the recess, the recess having a first length extending along a longitudinal axis of the guide tube;
- the main portion including a section of reduced cross-section disposed adjacent the first end for defining a waist of narrower cross section than a maximum cross section of the sleeve, the waist having a length extending along the axis and is longer than the length of the recess;
- the method comprising the steps of:
- A) positioning the sleeve above clamping shoes of a rig, wherein the clamping shoes engage the waist, and the sleeve rests upon the clamping shoes;
- B) applying percussion to the threaded joint to loosen the thread connection;
- and
- C) unscrewing the joint.
Dependencies are inferred from the claim text.