Patent ID: 6102141
Filing Date: 2000-08-15
Classification: E21B

Abstract:
A rock drill for percussive drilling, comprising a shank; a collar connected to a front end of the shank; a rod portion extending forwardly from the collar; a rock cutter disposed at a front end of the rod portion; and a central flush channel extending from a rear end of the shank toward the front end of the rod portion; the shank, the collar and the rod portion forming an integral one-piece unit; the flush channel being of circular cross sectional shape and having a substantially constant diameter along substantially its entire length; a ratio of a diameter of the flushing channel to a smallest outer cross sectional width of the rod portion being greater than 0.35 and less than 0.43, the central flush channel including an end wall closing off a front end thereof; and at least one branch channel extending outwardly from the central flush channel for conducting flushing fluid to a front end of the rock drill.