Experimental investigation on the breakage of hard rock by the PDC cutterswith combined action modes

To verify the feasibility and efficiency of rotary-percussive drilling assi sted by waterjets in very hard rocks, experiments on the performance of pol ycrystalline diamond compact (PDC) cutters resisting different combined loa ds of static thrust, impact, cutting and waterjets on Missouri red granite and Halston limestone were investigated. The experiments were conducted by means of a drop hammer and linear cutting-impact table. The effects of stat ic thrust (WOB). impact energy, impact spacing and waterjets on the rate of penetration in hard rocks are described and the results are analyzed by me asuring the depth of the craters or cuts penetrated by PDC cutters. Results from the study confirmed that the combined mode of cutting-impact is very effective in very hard rocks. (C) 2001 Elsevier Science Ltd. All rights res erved.