DTH hammer, also called down the hole ( DTH) hammer, is a kind of pneumatic rock drilling tool, DTH hammer is an integral part of the DTH Rig. The difference from others is that during DTH drilling process, down the hole hammer always stays at the bottom of the hole, impacting the rock by bit from DTH hammer directly.
The rotating power acting on DTH hammer comes from rotation motor on the drill rig, the pull force comes from feeding device and transfers the energy to DTH hammer through drill pipe; High-pressure air enters into the DTH hammer through DTH drill rods, then run out from DTH hammer bits, exhaust air is used to blow up cuttings from the bottom of the hole; The rapid hammering process shreds hard rock into small fragments and dust, they are then blown away by a fluid, be it air, water, or the drilling mud itself.
DTH Drilling technique was created to drill big holes vertically in ground boring drilling and other industrial applications, such as metallurgy, coal, chemical industry, water conservancy, hydropower, highway, railroad, national defense, construction, and other engineering hole-forming operations.
You should keep the following points in mind while choosing the right DTH hammer for your projects:
1. DTH Hammer Size:
The selection of DTH hammer size is largely determined by the hole diameter and type of rock formation, 3.5 to 10 inches is the best range of blast holes for DTH drilling. Smaller holes are typically drilled with a top hammer rather than a DTH hammer, and larger holes generally use the rotary drilling technique; DTH rigs drill straight holes with less deviation providing more accurate blasting and better fragmentation as a result.
the size of the DTH hammer should be selected as close as possible to the size of the hole to be drilled. The larger the diameter of the DTH hammer, the larger the diameter of the piston, and the higher the working efficiency.
Ideally, the size of the hammer should match the required hole dimension as closely as possible, leaving just enough space for cuttings to evacuate the hole.
Usually, the smallest hole diameter a DTH hammer can drill is its nominal size. i.e. standard 127 mm (5′) hammer will drill a hole down to a minimum diameter of 127 mm (5′). The limiting factor is the outside diameter of the DTH hammer, because as the hole diameter reduces due to diameter wear of the bit, airflow is restricted. Maximum hole size for DTH drilling is the nominal hammer size plus 25 mm (1′), so for a 127 mm (5′) hammer the maximum hole size is 152 mm (6′).
2. DTH Hammer’s Air Consumption:
Usually best to choose a DTH hammer that is close to the highest operating conditions of the air compressor. The greater the working pressure of the DTH hammer, the better the working efficiency. If you cooperate with a manufacturer with creative and advanced technology, it is also possible to obtain better results and performance of the DTH hammer when used under different conditions.
3. DTH Hammer’s Feature:
DTH drilling results mostly depend on the design and working pressure.
A: Design
VD Drill’s DTH hammers are purpose-matched for all rock types and applications where high performance and low total cost per drill meter are the main criteria. The standard design is a suitable choice for production drilling in quarries, shallow water well drilling, and underground blast hole drilling. For demanding conditions in abrasive formations, VD Drill has its own technical DTH hammer type. It has the same internal components as the standard DTH hammer, but with larger OD of the chuck and wear sleeve, and a top sub-fitted with tungsten carbide buttons for wear protection in harsh and abrasive conditions. These also protect the top sub from excessive wear when rotating out of the hole through broken rocks.
B: Working Pressure
Usually using impact energy and impact frequency (strokes/min), to describe a DTH hammer, simply, a DTH hammer with small impact energy and high impact frequency drills well in soft, fractured formations, and the opposite is true in hard rock formations.
Conclusion
When choosing the right DTH hammer, we need to base the selection on the required drill hole size, the air consumption obtained, the feature of the different formation models, and the drilling cost of DTH hammers.
Want to know VD DRILL Advanced DTH Hammer, please click article :
Best Value in Design DTH Rock Drilling Tools and its work-effective rock drill tools partner
More information for DTH Hammers, Contact our Expert or Ask For A Quote.
Browse our website www.drillbitsupplier.com to learn more.