According to principle of impact crushing rock drill works. Piston do high frequency reciprocating motion at work, constantly impact shank. Under the action of impact, pointed wedge shaped bits will be crushed rock and carved into a certain depth, forming a dent. After the piston return, nager turned a certain Angle, the piston to move forward, again shock shank, and form a new dent. The fan rock between the two grooves are produced by drill head horizontal component of the shear. Piston impact shank, don't break the ground and from the center of the drill hole continuously input pressure of compressed air or water, and the slag discharge port, the formation of a certain depth of circular hole.