What is percussion rock drilling?
Percussion rock drilling is characterized by the drilling tool breaking the rock by means of chiseling, including three main processes: chiseling, rotary and slag removal. Rock drills are used to drill shallow boreholes and small-diameter deep holes, while submersible drills and corded percussion drills are used to large-diameter deep holes.
Rock drills are suitable for drilling in medium-hard rock, the diameter of the borehole is usually 35-65mm, and the depth is generally not more than 15 m. According to the power of pneumatic, hydraulic, electric and internal combustion. At present, the most widely used pneumatic rock drill. Hydraulic rock drill with high speed, low power consumption, low noise, is being popularized in global countries. The drilling tool consists of drill bit, drill rod and shank adapter. When drilling shallow holes, the shank and rod are usually a single unit, and the rod is equipped with a movable bit. When drilling deep holes, the shank, rods and bis are made separately, and the rods are lengthened one by one with the deepening of the holes. Rock drills are mounted on air legs, drilling frames or rock drilling trucks.
At present, widely used chain piece or columnar tungsten carbide bits. For drilling shallow holes, a zig-zag chip alloy bit is used, and for drilling deep holes or shallow holes in rocks with developed fissures, a cross-shaped or d-shaped bit. Cylindrical alloy bits are suitable for rock drills with large impact power and low rotational speed, drilling holes with a diameter of more than 40mm. Drill rods are used to transmit impact energy and torque, and are made of hexagonal or round with hollow alloy steel. Shank adapter are directly subjected to the impact of the piston, and their shapes and sizes depend on the type of rock drill. Shank adapter, rods and bits are heat-treated according to the conditions of use and material to improve service life.