Down Hole Drilling (DTH)
Down-the-hole drilling (DTH),the force generated when the piston in the hammer strikes the bit creates a shock wave on the rock.
Down-the-hole drilling (DTH), the force generated when the piston in the hammer strikes the bit creates a shock wave on the rock. When pressure is applied to the bit under load, a pressure-induced bonding surface is formed between the bit and the rock. The adverse reaction of the rock to this pressure depends on the characteristic of the rock and the compressive load.
DTH drilling is often used in the mining industry (blast hole drilling), on construction sites, drilling water wells, and in the oil and gas industry. In drilling for blasting and drilling purposes, holes of the desired diameter can be drilled with different drilling hammer bits.
The energy source of the system is compressed air. Drilling speed increases with the air pressure used, more air pressure means higher drilling speed. Because of, manufacturers manufacture downhole hammer bits that can work up to 25 bar pressure. The downhole drilling system is preferred because of its disadvantages such as more air requirement, low drilling speed, as well as the following advantages; The hammer should be selected appropriately according to the current compressor capacity used. It should be known that; hammer compressor will use an average of 85% of its air production capacity. The bit should be selected in accordance with the most efficient drilling according to the rock type.
Advantages of DTH
● Reduction of in-hole deviations
● Drilling long holes with little decrease in drilling speed due to efficient transfer of impact energy to the hole bottom
● Good cleaning of the inside of the hole, even on cracked lands
● An easy-to-use drilling system for the operator
Compressor, on the machine or as a separate unit, provides the transmission of air into the system. The aim is to ensure that the air is transmitted to the hammer with minimum loss. The airflow is amplified by being compressed inside the hammer, and this air drives the hammer, whose operation is set to cycle.During one cycle of the piston, air is released from the hammer twice, allowing water and rock shards to be transported during drilling. The aim is to spend the air in the most effective way.
Hammers save time and therefore fuel, especially with their drilling speed. The special internal structure of the hammers has been designed according to new rock drilling technologies.