DTH Bit

DTH hammer is a kind of pneumatic rock drilling tools, the difference from others is during drilling process hammer always stay in the bottom of the hole, impact the rock by bit from hammer directly. High pressure air enter into the hammer through drill pipe, then run out from drill bits, exhaust air are used to blow up cuttings from the bottom of hole. The rotating power acting on DTH hammer comes from rotation motor on the drill rig, the pull force comes from feeding device and transfer the energy to hammer through drill pipe.

DTH hammer basic structures

DTH hammer components: Piston, internal cylinder, air distributor, check valve and drill bit accessories are installed in the external cylinder, the external cylinder has the top sub connected with its connection thread & wrench , there has a drive chuck threaded to the other end of cylinder. There is spline in the drive chuck which is mainly used to transfer feeding and rotational force to the drill bit. The stop ring controls the axial movement of the drill bit, and the check valve is used to prevent cutting and other foreign materials ingress into hammer in case of air supplying is stopped. During drilling, the drill bit is pushed into the hammer and pressed against the drive chuck, where the piston directly impacts the drill bit for crushing rock. Hammer start to clean the bottom by blowing up when bit lift from the hole. 

DTH hammerwoking principle

1. Drilling bit press against the rock. 

2. High pressure air burst through the check valve from drill pipe, enter the front cavity of hammer. 

3. The increase of the front cavity volume push the piston to move upward. 

4. When the piston moves up to a certain extent, the front cavity deflates and the compressed air enter into the back cavity. Piston keep moving upward because of inertia. 5. When the piston to a certain extent, due to the compression of the back cavity and the increase of air pressure, the piston starts to impact downward which forming an impact stroke. Moves up circles as the above process to achieve impact and complete rock drilling. 

Type of DTH hammer

Classifying by hammers cutting blowing up way: Conventional DTH hammer & Reverse Circulation DTH hammer (RC hammer). 

Classifying by hammers air distribution and structure characteristics: Hammers with valve & Hammers without valve. 

Classifying by hammers rated working pressure: Low air pressure DTH hammer(rated working pressure 彡 0.7Mpa), Mid-Low air pressure DTH hammer(0.7Mpa< rated working pressure ( 1.5Mpa ), High air pressure DTH hammer(1.5Mpa< rated working pressured 2.5Mpa), Ultrahigh air pressure DTH hammer (rated working pressure>2.5Mpa) 

Classifying by the assorted bit which with or without foot valve: DTH hammers available for assorted bit which with foot valve & without foot valve. 

Classifying by hammers outer diameter: 1 inch, 2 inch, 3 inch, 4 inch, 5 inch, 5.5 inch, 6 inch, 7 inch, 8 inch, 9 inch, 10 inch, 12 inch ,15 inch, 24 inch, etc.,

DTH hammer application

DTH hammers are widely used in geology exploration, civil construction project, water well drilling and construction foundation project.