GB280532A - Improvements in apparatus for earth and rock drilling - Google Patents

Abstract

280,532. Gildersleeve, A. M., and Dean, C. L. Nov. 10, 1926, [Convention date]. Borehole apparatus. - A drill for boring earth and rock has a number of frusto-conical rolling cutters of which the cutting edges engage the material at an angle less than 90‹ and the axes are skewed relative to their direction of travel; the cutters cut in annular paths of successively increasing diameters. As shown, the drill head 10 carries flat-bottomed frusto-conical cutters 15 - - 18 which cut a hole with a base as in Fig. 4, the cutter 15 cutting the inner annulus and the cutter 16, 17, 18 respectively cutting successively greater annuli. Each cutter has a shank 19 entering a bushed aperture in the head and bearing against a ball 22 which is retained in place by a plate 23; a pin 24, Fig. 3, is pressed by a spring 26 into engagement with an annular recess 25 in the spindle to retain the latter in the head. Each spindle 19 is inclined upwardly in the direction of rotation of the head; the spindle of the cutter 16 also inclines upwardly away from the axis of the head, and those of the cutters 15, 17, 18 towards the axis. More than one cutter may be provided to work in the same annular path. The hole drilled is of larger diameter than the bit. Water &c. is supplied through a central passage 31 and ports 32 - - 36 to remove cuttings &c.