Cluster down-the-hole drill - for large-dia. wells with separate rotation of each hammer superimposed to common rotation

摘要

A percussive drilling equipment for large-dia. wells has a first set of drill tubes which are driven by a rotation motor and carry at the forward end several down-the-hole hammers. A coaxial second set of tubes is stationary but carries a gear rim which meshes through idler wheels with gears on the down- the-hole hammers to revolve them. The individual rotation of each down-the hole hammer, superimposed to the rotation by the first set of drill tubes, ensures a uniform wear of all areas of all drill bits.