Inventors:
Roy N. Sonomura - Hilo HI
International Classification:
E21B 712
Abstract:
So that explosives can be placed in an underwater hole in rock efficiently, a rock drilling machine having a rock drill mounted for extension and retraction on a strut which can be forced against a surface to be drilled, has a short debris guard tube fixed to the strut so as to extend beyond the terminus of the strut so that the debris guard may be forced against and held against the surface of the rock to be drilled. In such a machine having a very long strut and drill rod for drilling holes in rock submerged at a depth of water over four feet, a drill guide tube fixed to the strut between the debris guard and the drill has a full length door. After the hole has been drilled to depth, the drill rod is retracted from the debris guard and deflected to one side (and out of the drill guide tube door of the long strut version) and a long explosives placement tube is inserted through the debris guard tube into the hole. The debris guard is then slipped off and freed from the placement tube by retracting the strut. The upper end of the placement tube is left above the water surface, marking the hole location and allowing later placement of explosives while drilling continues at other locations.