Percussion drilling apparatus and torque transfer method

Abstract

A drill rod for transferring torque comprises a casing for connection in a drill string. The casing is coupled to an internal body by a torque transferring mechanism at each end of the casing such that torque applied to an end of the drill rod is transferred through both of the casing and the body.

1 .- 18 . (canceled) 
     
     
         19 . A drill rod for transferring torque comprising a casing for connection in a drill string; the casing coupled to an internal body by a torque transferring mechanism at each end of the casing such that torque applied to an end of the drill rod is transferred through both of the casing and the body. 
     
     
         20 . A drill rod according to  claim 19 , wherein the torque transferring mechanism comprises a splines and complementary mating portions. 
     
     
         21 . A drill rod according to  claim 20 , wherein the splines are configured to engage with the complementary mating portions, forming a splined connection to transfer torque. 
     
     
         22 . A drill rod for transferring torque comprising a casing for connection in a drill string; the casing coupled to an internal body by a torque transferring mechanism at each end of the casing such that torque applied to an end of the drill rod is transferred through both of the casing and the body, wherein the torque transferring mechanism comprises a splined connection between splines and complementary mating portions to transfer torque. 
     
     
         23 . A drill rod according to  claim 19 , wherein torque applied to the casing is also applied to the internal body. 
     
     
         24 . A drill rod according to  claim 19 , wherein torque applied to the internal body is also applied to the casing. 
     
     
         25 . A drill rod according to  claim 19 , wherein the casing is separable from the internal body. 
     
     
         26 . A drill rod according to  claim 19 , wherein the internal body has one or more fluid supply channels and a fluid return channel. 
     
     
         27 . A drill rod according to  claim 19 , wherein the casing comprises complementary mating portions at both ends and the internal body comprises splines at both ends. 
     
     
         28 . A drill rod according to  claim 19 , wherein the complementary mating portions of the casing are configured to slidably receive the splines of the internal body. 
     
     
         29 . A drill rod according to  claim 19 , wherein an outer diameter of the splines at a first end of the internal body is smaller than an inner diameter of the complementary mating portion at a second end of the casing, so that the internal body is required to be slidably inserted into the casing from the second end. 
     
     
         30 . A drill rod according to  claim 19 , wherein the torque transferring mechanism extends continuously around an entire annular portion between the internal body and the casing. 
     
     
         31 . A drill rod according to  claim 19 , wherein the torque transfer mechanism comprises a continuous complementary mating profile protruding inwardly from the casing and a continuous splined profile protruding outwardly from the internal body. 
     
     
         32 . A drill rod according to  claim 19 , wherein the or each torque transferring mechanism can be coupled to another drill rod having one or more annuluses. 
     
     
         33 . A drill rod according to  claim 19 , wherein the drill string comprises a percussion drill bit and a measuring instrument. 
     
     
         34 . A drill rod according to  claim 19 , wherein an upper end of the internal body comprises connection means for fluidly connecting to a multi annulus drill rod above the torque transferring mechanism located at the upper end of the internal body as well as to another multi annulus drill rod below the lower torque transferring mechanism located at a lower end of the internal body. 
     
     
         35 . A method of transferring torque from one end of a drill rod to another comprising transferring torque via both a casing and an internal body. 
     
     
         36 . A method of transferring torque according to  claim 35 , wherein the method further comprises transferring torque from a first end of the drill rod to the casing and the internal body. 
     
     
         37 . A method of transferring torque according to  claim 36 , wherein the method further comprises transferring torque from the casing and the internal body to a second end of the drill rod.