By DE Editors
Brandon Fisher, Center Rock founder and CEO (left), with Richard Soppe, down-hole-drill project manager, and their worn 26” Low Profile drill that made the final bore to the Chilean miners, 2,067 feet below the surface.
Gibbs and Associates, developer of GibbsCAM software for programming CNC machine tools congratulates GibbsCAM user Center Rock on its role in the October 2010 rescue of 33 trapped Chilean miners. It is estimated that Center Rock’s Low Profile (LP) Hole Opener drills, which were produced with machine tools programmed with GibbsCAM, shortened the rescue effort by two and a half months.
Center Rock Inc., of Berlin, PA, has been using the GibbsCAM mill-turn and 3-axis milling modules since 2005, and GibbsCAM rotary milling and MTM modules since 2006. The integrated GibbsCAM modules open SolidWorks CAD models directly, so that Center Rock programmers can use and manipulate engineers’ solid-model geometry to program their seven CNCs. For turning operations, Center Rock uses three Doosan 2-axis lathes: a Puma 300, a Puma 400 and a Puma 480. Three-axis milling and rotary milling is done on two Mazak horizontal machining centers, while parts with complex geometry and parts that would otherwise require multiple set-ups on lathes and machining centers are made with two Doosan Puma MX2500 multi-task machine tools.
Unlike the drills used by the two other drillers attempting to reach the Chilean miners trapped 2,067 ft. below the surface, Center Rock’s drills use highly compressed air instead of fluids to drive drill bits and clear rock fragments. Other drills grind through rock, typically with roller cone bits, flushing and clearing the ground rock away from drill bits with water or other fluids. A Center Rock drill uses multiple pneumatic hammers, each steadily pounding a drill bit to crush rock as the drill rotates, much like a group of rotating jack hammers. In addition to driving the hammers, the compressed air is circulated to blow rock flakes and dust upward away from the bits. These newer DTH (down the hole) drills cut through hard rock much faster than fluid-operated systems, according to the comapny.
Center Rock uses GibbsCAM to program all their CNC machine tools, including their Doosan MX2500 multi-task machines, which are used to machine complex parts and all Low Profile drill bits. Here, GibbsCAM Cut Part Rendering displays multiple views of toolpath for machining the 7-7/8” LP drill bits loaded on the 26” and 28” LP drills.
In the Chilean miner rescue, Center Rock used three drill sizes to reach the 33 miners 2,067 ft. below the surface. The first was its 5.5 x 12 QL 120 hole opener, used to widen one of the ventilation holes from its 5.5 in. diameter to a 12 in. diameter that larger drills could use as a guide or pilot hole. The second and third were LP (low profile) drills of 28 in. diameter and 26 in. diameter, respectively, both configured as hole openers, and each using four pneumatic hammers and four, 7-7/8 in. diameter, tungsten steel drill bits.
Among the machined components for the LP drills are the flange and receivers at the top, the flat plates, the chucks for the hammers, and a long, serrated pilot or “nose.” However, the hardest parts and those with the most complex geometry are the LP drill bits, which Center Rock manufactures with various face shapes for specific applications. In addition to turning operations, areas of each bit may require flat, contour, radial or axial milling, and each bit may require various holes at different angles. These features, combined, lend themselves well to multi-task machining. With GibbsCAM MTM software and the Doosan MX2500, Center Rock programmers and machinists make each bit in a single set-up.
Sources: Press materials received from the company and additional information gleaned from the company’s website.