ROCK DRILL BIT WITH THREE SPIRAL FLUTES AND A SINGLE BLADE TIP THAT EXTENDS BEYOND THE DRILL AXIS WITH CHIP FORMING TEETH

摘要

591782 Disclosed is a rock drill bit for increased drilling progress. The drill bit comprising a shank fitted with a clamping end and a drilling tip at the end away from the clamping end, the drilling tip comprising three blades which are alar in topview. The blades each comprise at their top side a lip constituted by a leading chipping face and a trailing flank, the lips substantially converging onto each other within a central zone centred on the drill bit axis. In the central zone, a single long lip runs through the bit axis or runs a distance laterally offset from and past the bit axis and comprises a commensurate overshoot segment extending beyond the bit axis that in the vicinity of the bit axis. The long lip constitutes a chisel edge and in that the chisel edge comprises two radially outer ends axially projecting from the in-between centre of the chisel edge.