Relying on its own air distribution system, the compressed air enters the front and rear air chambers of the piston (hammer) alternately, so that the piston reciprocates continuously. The alloy ball teeth break the rock. According to the structural characteristics of the gas distribution system, the DTH hammer is divided into two types: valve type and valveless type.
(1) DTH hammers with valve. The airflow is controlled by the valve plate and can be divided into side exhaust and central exhaust according to the exhaust mode. The side-exhaust valve DTH hammer is the earliest used, and its exhaust gas is discharged from the side of the hammerhead. The exhaust gas of the central exhaust valve DTH hammer is discharged from the central hole of the hammerhead. In comparison, the effect of removing cuttings by the central exhaust method is good, the service life of the hammerhead is long, and the drilling efficiency is high.
(2) Valveless DTH hammer. There is no valve plate, and its gas distribution system consists of a group of holes arranged on the cylinder wall, which automatically distributes gas during the movement of the piston. In the total stroke of the piston movement, one section relies on the expansion of compressed air to do work. Under the same pressure conditions, the consumption of compressed air is only 2/3 of that of the valved DTH hammer.
According to the working pressure, the DTH hammer is divided into low-pressure DTH hammer (0.5～0.7MPa), medium-pressure DTH hammer (0.56～1.05MPa) and high-pressure DTH hammer (0.56～2.46MPa), which are suitable for different working conditions.
