Drilling-rig for blasting holes - has hydraulically-operated reversing drive between boring bar and crown-shaped bit

摘要

The boring bar is in sections (1), with a crown-shaped bit (6) at the free end, being fed forward and retracted by a chassis with feed and flushing heads. An in-hole hammer acting between the bar and the bit is hydraulically operated, and the bit is rotated to-and-fro. The drive mechanism (5) rotating the bit acts between the latter and the bar, and is hydraulically actuated via the pipes (3) supplying the hammer. There can be an accumulator (26) between the hammer and the bar, and the bit can be turned to-and-fro through an angle of between 180 and 350 deg. by a drive mechanism with rotary piston. The feed head can act as a clamping head, engaging with protrusions on the bar, so as to transmit pressure to the hammer and absorb the torque reaction from the drive mechanism. USE/ADVANTAGE - Alternating loads on bar are reduced on drilling rig used for prodn. of blasting holes.