Drilling tool

Abstract

The invention relates to a drilling tool for drilling soft and fragmented rock. The drilling tool disclosed in the invention comprises a portion having a round cross section and a smooth surface and positioned substantially symmetrically relative to the middle axis of a drill rod and comprising, at its end, a converging part through which conduits pass for rinsing medium.

1 . A drilling tool for drilling soft and fragmented rock, which tool comprises a portion having a round cross section and a smooth surface and positioned substantially symmetrically relative to the middle axis of a drill rod and comprising, at least at the end intended to be positioned towards the rock drill, a part converging towards the axis of the drill rod, and that the tool comprises, for rinsing medium, through-going conduits that terminate in said converging part, wherein the largest outer diameter of the tool is dimensioned smaller than the outer diameter of the drill bit intended to be used therewith. 
   
   
       2 . A drilling tool as claimed in  claim 1 , wherein the drilling tool is a part separate from the drill bit and both of its ends are provided with a part that converges towards the axis of the drill rod and that the conduits for the rinsing medium lead from the converging part to an opposite, converging part. 
   
   
       3 . A drilling tool as claimed in  claim 2 , wherein the middle part of the drilling tool is substantially cylindrical and that one end of the drill rod is provided with an external thread, the other being provided similarly with an internal thread for connecting the drill bit and the drill rods, respectively, thereto. 
   
   
       4 . A drilling tool as claimed in  claim 2 , wherein the drilling tool is installed at the end on the side of the external thread of the drill rod of a normal length. 
   
   
       5 . A drilling tool as claimed in  claim 1 , wherein the drilling tool is a part integrated into the drill bit.