Downhole hammer and bit manufacturer Rockmore International Inc. has designed a new “retrac”-type bit that the company says aids in pushing rock debris out of the way during retrieval.
“Our field support engineers recognized the need for better bit retrieval in face drilling operations,” says Pejman Eghdami, executive vice president. “After close collaboration with various drilling teams, our designers introduced the innovative ‘retrac’ features in this new reaming bit.”
The company explains in a release that reaming-type bits enlarge existing blastholes for effective blasting and rock fragmentation. This is typically performed in tunneling, mining, and underground construction drilling operations. The larger reamed holes are not loaded with blasting agents and therefore allow the rock formation to implode during the explosion phase. The voids in these reamed holes promote better rock fragmentation and, ultimately, more efficient blasting patterns.
After blastholes are drilled in the tunnel face with hole diameters ranging from 43-51 milimeters, certain holes in the pattern are enlarged with a typical reaming bit to 76-102 milimeters, depending on the blast and rock formation requirements. Standard reaming bits feature face designs with dome or narrow nose fronts and are intended to effectively enlarge a predrilled hole. When retrieved, however, after reaching target hole depth, they often seize up due to the loose rock debris inside the hole formation.
The company says Rockmore engineers addressed the challenge of retrieving these style bits by developing this new model that features “retrac”-style cutting fins in the rear section. The fins push out rock chips trapped behind the bit when the drill string is pulled from the blasthole, resulting in more efficient reaming operations in underground drilling operations.
Rockmore International Inc., founded in 1948, designs and manufactures a range of rock drilling tools for mining, construction, water well and other markets. The company is based in Wilsonville, Oregon. For more information, visit www.rockmore-intl.com.