Parallel alignment of rock drill slide - uses laser beam illuminating three glass bulbs for shot blasting holes in tunnels

摘要

When parallel shotholes have to be drilled during driving tunnels and headings in mines, a lack of parallelism caused by the conventional mechanical and hydraulic booms results in high explosive consumption. This can be avoided and the drill rig itself need not be previously aligned if a laser (6) with a revolving right-angle prism (7) is attached parallel to the rock drill slide (5). A guide rod (3) which is inserted into a pilot borehole (2) in the tunnel face (1) carries three markers (4), eg glass bulbs which light up when hit by a laser beam. The slide is aligned properly when all three markers light up simultaneously.