LOW STRESS CAVITY FOR CONICALLY CONNECTING DRILL BITS

A percussive drill bit comprising a sleeve section and bit section having a longitudinal axis; wherein the sleeve section has an axial end at the opposing end of the drill bit compared to the bit section from which a generally conically shaped internal cavity extends from for receiving a conically shaped drill rod to form a conical frictional connection; wherein the cavity has a conical region nearest to the axial end and a cylindrical region nearest to the bit section; characterised in that: there is connection section joining the conical region to the cylindrical region; the conical region has a straight tapered region with a starting point adjacent to the connection region; wherein the connection section has at a first curved connection region having a first radius, CR1, wherein its tangent,CT1, is positioned at a first distance, CD1, from the taper region starting point.