The down the hole drilling rig is an impact rotary drilling rig, and its internal structure is different from that of a general rock drill. Its gas distribution and piston reciprocating mechanism are independent, namely the impactor. Its front end is directly connected to the drill bit, and its rear end is connected to the drill rod. During rock drilling, the impactor penetrates into the hole and, through a valve, the piston (hammer) inside the impactor moves back and forth to strike the tail of the drill, causing the drill bit to impact the rock at the bottom of the hole. The high-speed rotation of the impactor inside the hole is achieved by a separate rotating mechanism, namely an electric motor or pneumatic rotating device outside the hole, through a drill rod connected to the rear end of the impactor. The rock powder generated during rock drilling is flushed out of the hole by a mixture of wind and water gas. The mixed gas is injected into the impactor through the center of the drill rod by the powder discharge mechanism, and then enters the bottom of the hole through the gas groove on the impactor cylinder body.
