Improvements in and relating to drilling in rock and other hard substances

Abstract

Abstract 740,468. Percussive drills. MEUTSCH, A. Feb. 4, 1953 [Nov. 25, 1952], No. 3133/53. Drawings to Specification. Class 124. Rock and like hard material is bored by a rotary and percussive drill in which the speed of rotation and the number of blows struck per minute is such that the notch spacing at the periphery of the drill is regulated according to the hardness of the rock and is for'soft rock 6-9 m.ms, for medium rock 3-6 m.ms, and for hard rock 1-3 m.ms. A drill of the type described in Specification 686,185 having valves controlling the supply of air to the rotary motor and the percussive motor may be used, and such drill may be modified by the addition of gearing to the rotary motor. With 3,000 blows per minute the rotary speed may be 220 r.p.m. and with 6,000 blows per minute the rotary speed may be 440 r.p.m. for a rock having a hardness of 70 Shore. A formula is given for determining the notching space from the drill diameter, the number of blows per minute, and speed of rotation. Reference has been directed by the Comptroller to Specification 686,185.

Inventors

No inventors recorded.

Bibliographic Details