rock drills

The drill bit strikes the surface of the stone with a force of 25 tons up to 140 times per second. Its task: to drill 80 holes where explosive charges are inserted. They blast away rock for supply tunnels for underground mining or for road construction. The drill bits are driven by rock drills. Two factors are decisive in keeping operating costs low: On one hand, the holes must be drilled very quickly, even in hard stone such as granite, which requires very powerful forces. On the other hand, despite the strong forces, maintenance intervals are supposed to increase. With the development of its new machine, the COP MD20, Atlas Copco has resolved its conflicting objectives: Without a reduction in the machinery’s rate of advance, the company was able to double its maintenance intervals.

A new sealing system from Freudenberg Sealing Technologies was the key component in accomplishing this, as the metallic components, especially the piston that drives the drill bit, had been previously optimized by using special high-strength alloys. But the forces that are produced, especially during the bit’s recoil, are so high that they severely stress the seals in this high-pressure hydraulic system. If the seals develop wear, the result can be leakage, which has a highly negative effect on the relationship between the applied energy and the boring power – in other words, the system efficiency declines.