Release assembly for percussion drill tools

Abstract

According to an aspect of the present invention, there is provided a release assembly ( 100 ) disposable axially between two components (A, B) of a percussion drill tool ( 10 ), wherein the components (A, B) are connectable together by means of a screw-threaded connection ( 20 ). The release assembly ( 100 ) comprises a release ring ( 102 ), the release ring ( 102 ) being tapered on at least a first side ( 103 ) in a first radial direction. The release assembly ( 100 ) also comprises a first counter element ( 105 ) arranged axially adjacent the first side ( 103 ) of the release ring ( 102 ), the first counter element ( 105 ) having a tapered side ( 106 ) for engagement with the first side ( 103 ) of the release ring ( 102 ).

1 . A release assembly disposable axially between two components of a percussion drill tool, wherein the components are connectable together by means of a screw-threaded connection, the release assembly comprising:
 a release ring, the release ring being tapered on at least a first side in a first radial an outward direction;   a first counter element arranged axially adjacent the first side of the release ring, the first counter element having a tapered side for engagement with the first side of the release ring.   
     
     
         2 . A release assembly as claimed in  claim 1 , wherein the release ring comprises a plurality of separate sectors, or a single element divisible into a plurality of separate sectors, such that the sectors of the release ring are moveable in an inward direction to shorten an axial length of the release assembly. 
     
     
         3 . A release assembly as claimed in  claim 1 , wherein the release ring is tapered on a first side and a second side, and further comprising a second counter element arranged axially adjacent the second side of the release ring, the second counter element having a tapered side for engagement with the second side of the release ring. 
     
     
         4 . (canceled) 
     
     
         5 . A release assembly as claimed in  claim 1 , wherein, when the release assembly is disposed between the components of the drill tool, a radial clearance ΔR is provided between an inner circumference of the release ring and one of the components. 
     
     
         6 . A release assembly as claimed in  claim 1 , wherein removable means are provided to maintain the radial clearance ΔR between the inner circumference of the release ring and a component of the percussion drill tool. 
     
     
         7 . A release assembly as claimed in  claim 1 , wherein the release ring comprises at least three separate sectors, or a single element divisible into at least three separate sectors, and a circumferential clearance is provided between adjacent sectors. 
     
     
         8 . (canceled) 
     
     
         9 . A release assembly as claimed in  claim 1 , wherein the release ring comprises a plurality of separate sectors. 
     
     
         10 . A release assembly as claimed in  claim 1 , wherein the release ring comprises a single element, divisible into a plurality of separate sectors while the release assembly is disposed between the components of the drill tool. 
     
     
         11 . A release assembly as claimed in  claim 10 , wherein the release ring comprises a plurality of weakened regions spaced around the circumference of the ring, such that the ring is adapted to be divided into a plurality of sectors at the weakened regions. 
     
     
         12 . A release assembly as claimed in  claim 11 , wherein each weakened region comprises a portion of reduced thickness, such that the ring is divisible into a plurality of separate sectors at the portions of reduced thickness. 
     
     
         13 . A release assembly as claimed in  claim 11 , wherein the radial length of the release ring is reduced at the weakened regions. 
     
     
         14 . A release assembly as claimed in  claim 1 , wherein the or each counter element is integrally formed with one of the components of the drill tool. 
     
     
         15 . A method for releasing a screw-threaded connection between components of a percussion drill tool, the method comprising:
 disposing a release assembly axially between two components of a percussion drill tool, wherein the release assembly comprises a release ring tapered on at least a first side in an outward direction and a first counter element arranged axially adjacent the first side of the release ring, the first counter element having a tapered side for engagement with the first side of the release ring;   connecting the components together by means of a screw-threaded connection; and   deploying the release assembly by dividing the release ring into a plurality of sectors and moving the sectors of the release ring in an inward direction to shorten an axial length of the release assembly.   
     
     
         16 . A method for releasing a screw-threaded connection between components of a percussion drill tool, the method comprising:
 disposing a release assembly axially between two components of a percussion drill tool, wherein the release assembly comprises a release ring tapered on at least a first side in an outward direction, wherein the release ring comprises a plurality of separate sectors, and a first counter element arranged axially adjacent the first side of the release ring, the first counter element having a tapered side for engagement with the first side of the release ring;   connecting the components together by means of a screw-threaded connection; and   deploying the release assembly by moving the sectors of the release ring in an inward direction to shorten an axial length of the release assembly.   
     
     
         17 . (canceled)