CONTROL METHOD AND CONTROL DEVICE FOR A DOWN-THE-HOLE ROCK DRILL

摘要

When drilling deep boreholes with a down-the-hole drill (15), the pressure and the flow of the motive fluid are controlled so that the impact velocity of the piston hammer of the drill is kept within narrow limits independently of the counter pressure in the borehole. For this purpose the quotient of pressure and flow can be held substantially constant.