PCD bit developments to improve bolt load transfer and decrease drilling times

The development of the Poly-Crystalline Diamond (PCD) bits for use in underground coal mines has historically utilised the technologies and improvements developed for the oil and gas industry. For smaller bit diameters (27 to 29 mm) utilised in development panels that have hard and/or abrasive strata in the primary bolted horizon, the technology improvements of the PCD cutters themselves can be applied from the oil and gas industry. However, the design of the drill bit body needed input from an alternative influence to drive improvements in penetration rates, increased bolt load transfer and decreased loading on the drilling equipment. This paper will discuss these alternative influences and their involvement in the design changes that were investigated and eventually implemented in prototypes, proven in a test rig and ultimately field trialled.