| Abstract: | Earlier work has shown that the use of water jets at moderate pressure enhances mechanical cutting in hard rock. To assess the potential of this technique for use in conjunction with free-rolling cutters, a series of laboratory tests was conducted with disc and button cutters to determine the effect of variations in the jet and cutting parameters on the cutter performance. In these tests, it was found that the use of water jets at pressure in the range of 5–40 MPa can reduce the forces on a free-rolling cutter by 40 per cent, which represents a significant improvement in cutting performance. The reduction in thrust force was found to be dependent on jet pressure: the greater the pressure, the greater the reduction. The reduction in rolling force was independent of jet pressure over the range investigated. The results indicate that no additional improvements in cutting performance of any significance are to be gained by an increase in jet pressure above 40 MPa. The most effective jet configuration for the reduction of cutter forces was found to be four coherent water jets, two laterally disposed on each side of the cutter and directed at the arc of contact between the cutting edge and the rock. |
