GB191310139A - Improvements in or relating to Drilling and Boring Apparatus. - Google Patents

Abstract

10,139. Bambridge, W. G. April 30. Percussive drills.-A drill of the rotary percussive type comprises a rotating screw-threaded drill spindle, a feed-nut, and a block reciprocating on the spindle, the block being moved in one direction bv co-operating means on the spindle and in the other direction by a spring, and imparting a blow to the spindle. In the form shown, the drill spindle 1 has a buttress thread and is rotated in a bearing 2 from worm gearing 4, 8 or bevel-gearing, by means of a key passing through a rotatable sleeve 6 and engaging a groove in the spindle. The bearing 2 may be of aluminium with a brass liner. The feed-nut 19 has a conical end engaging a conical recess in a spring-pressed collar 16 which is held against rotation. The spindle rotates a sleeve 12 and a collar 13. and rollers 23 on the collar engage cam-surfaces on a block 11 to move this against the resistance of a spring 29, which then returns the block to impart a blow to the spindle through the collars 13, 16 and the nut. The block 11 may be held back out of operation by a catch or by lateral extensions of slots 28 which guide the block. The nut 19 may be in halves held together at the front end by wing- nuts and bolts and at the rear end by the collar 16. The Provisional Specification states that the drill may be rotated intermittently and that the feed-nut may open automatically to allow the spindle to move through it when struck; further, the nut may be rotatable but normally held by a pawl &c. which is automatically released periodically by a cam &c. to reduce the feed, and the position of the cam-surfaces and their engaging-rollers may be interchanged and a tension spring may replace the spring 29; also detachable weights may be secured to the block 11 to increase the blow.