ADJUSTABLE DRILL UNIT FOR CHURN DRILLS AND THE LIKE

摘要

1278835 Rotary and percussive drills TRIDENT INDSUTRIES Inc 30 Sept 1969 47988/69 Heading B3C [Also in Division B4] A rotary and percussive drill bit comprises cutters 42, 50, secured in cavities 38 by a screw 54, shims 60 being provided for adjusting the radial positions of the cutters. Tungsten carbide reaming portions 64 may be provided on the drill bit shank 32, on the cutters, or on both the shank and cutters. The cutters may have carbide inserts 48, and a projection 62 is provided for breaking up the non-drilled material. Screw 54 may be replaced by two screws, one for each cutter, or by a nut and bolt. Three or more cutters may be provided.