The invention of the DTH hammer has been around for nearly a century. It was initially used for drilling and blasting in quarrying and surface mining operations.
The Birth of DTH Hammers
In 1857, Italian engineer Bartritt invented the world's first pneumatic rock drilling rig powered by compressed air pressure, marking the beginning of a new era in DTH drilling.
In 1932, the Ingersoll Rand Company in the United States invented the DTH hammer, which features the delivery of the drill machine to the bottom of the hole, thus reducing energy loss.
By the late 1940s, DTH hammer was being used for surface mining.
In 1951, Belgian engineer Andre Stenuick designed and manufactured a DTH hammer, that has a similar structure to the modern DTH hammer.
The Rapid Development of DTH Hammers
Ingersoll Rand has played a world-leading role in developing new fields and types of pneumatic DTH hammers.
In 1955, the company introduced a new downhole drilling design and began to truly commercialize downhole drilling.
During the 1960s and 1970s, the DTH hammer technology underwent rapid changes.
A major change in the DTH technology is the introduction of a valvless DTH hammer.
The early DTH hammer has a valve, and the practice has proved that the drilling speed of DTH hammers largely depended on the pressure of air pressure. The greater the pressure, the greater the drilling speed.
The change to valveless DTH hammers was made to reduce the consumption of air pressure when using high-pressure compressed air.
Valveless DTH hammers consume less air because they do not need to fill the space between the inner cylinder and the wear-resistant casing with compressed air to activate the check valve for each impact.
In addition, the valveless DTH hammers rely on the movement of the piston for automatic air distribution, and the only moving part is the piston, which has a simple structure, easy maintenance and good performance.
Valveless DTH hammers have been extensively tested in the UK and other countries, and have maintained a high mechanical drilling speed and extended service life compared to valved DTH hammers.
Development of High Pressure DTH Hammers
The air pressure used in DTH hammers has been increasingly higher in order to solve drilling efficiency problems in extremely hard and abrasive rocks.
The air pressure of general DTH hammers is roughly below 1.4 Mpa , while high-pressure DTH hammers range from 1.7 to 2.47 Mpa.
In 1986, Halifax in the UK introduced the Mach 400 turbine high-pressure valveless DTH hammer, which could work with air pressures up to 3.5 Mpa.
DTH hammer has been extensively tested and used in Scandinavia for drilling very hard and abrasive rock formations, showing reliable performance and considerable mechanical drilling speeds.
Practice has proven that drilling speed is positively related with the compressed air pressure. With the development of air compressor technology, the air pressure that DTH hammers can use is getting higher and higher.
Development of water-powered DTH Hammers
In addition to compressed air pressure, the exploration of other media to power the DTH hammer has been ongoing.
In the early 1980s, Sweden's Atlas Copco began developing water-powered DTH hammers, and G-Drill continued this research, collaborating with Sweden's LKAB in 1988. Two years later, they finally developed the Wassara water-powered DTH hammer.
capable of drilling at any angle, require 10% less power, increased penetration rates by 2.5 to 3 times, and improved working conditions, showing a great development prospects in certain applications.
In the spring of 1990, the first test of DTH hammer was carried out at the LKAB-ownd iron mine, approximately 500,000 meters of drilling, showing several advantages: the ability to drill at any Angle, the reduction in power, the increased times in permeability, and the improved working conditions, showing a good prospect for DTH hammer in the applications.
Nowadays
Today, DTH hammers are widely used in surface and underground mines, quarries, hydroelectric projects, water well drilling, mineral exploration, geothermal mining, subway construction and other projects. Because of its high drilling precision, smooth borehole walls, unrestricted drilling depth and easy maintenance, the DTH hammer has received wide attention in the rock drilling industry.
