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Percussive Drilling With Independent Rotation.
NTIS: PB 213 953 :21 pages
The Bureau of Mines conducted drilling experiments in the laboratory with a commercially available percussive drill that has an independent rotational system. Eight rock types with a wide range of physical properties were drilled under several combinations of rotational speed, drilling thrust, and operating pressure. Penetration rates and energy per unit volume correlated well with the coefficient of rock strength as shown graphically. Size- distribution analyses of some of the drill cuttings show how particle size varies with rotation speed and rock hardness. In general, changing the rotational speed has a greater influence on the penetration rate in softer rocks, with penetration rate increasing with increasing rotational speed.
IH; Report of Investigations
NTIS Accession No.
NTIS: PB 213 953
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division