Penetration and impact resistance of PDC cutters inclined at
different attack angles①
different attack angles①
(1. College of Resource, Environment and Civil Engineering,
Central South University of Technology, Changsha 410083, P.R.China;
2. Rock Mechanics and Explosives Research Center,
University of Missouri-Rolla, MO65401, USA)
Central South University of Technology, Changsha 410083, P.R.China;
2. Rock Mechanics and Explosives Research Center,
University of Missouri-Rolla, MO65401, USA)
Abstract: In order to develop a rotary-percussive bit with diamond-enhanced cutters assisted by high pressure water jets, it is necessary to study the damage mechanism and the penetration properties of PDC cutters subject to different impact load level and rock types. Therefore the impact experiments of the single PDC cutters with different attack angles in four rocks: black basalt, Missouri red granite, Halston limestone, and a very soft (Roubidoux) sandstone were carried out, and the effects of rake angles of PDC cutters on both the penetration and impact resistance of PDC cutters have been discussed in detail. Test results show that a PDC insert can withstand a very strong impact in compression but is easily damaged by impact shearing, the PDC cutters are more easily damaged by shearing if the attack angles are relatively small, the 45°PDC cutters have the least penetration resistance among the cutters tested. Thus it is suggested that the attack angles of PDC cutters should be larger than 30°for bits which must withstand impact from a hammer.
Key words: PDC cutters; penetration and impact resistance; rotary-percussive drill bits