Patent GB-162774-A (GB)
Title: Improvements in drill-grinders
IPC: B24B3/24
Filed: 1920-02-03
Abstract: 162,774. Rose, W. Feb. 3, 1920. Twist drills, sharpening.-A machine for grinding twist and other drills comprises a base 1 adapted to be attached to a grinding-head and carrying a slide 2, which is adjustable to and from the grinding-wheel 23, to give feed to the drill, by a screw 3 and has a pivot 4 thereon. On the pivot are mounted two spaced arms 5 of a rocker 6, in which is rotatably mounted a sleeve 7 carrying a chuck 8, for holding the drill 9, and a handwheel 10. The sleeve has a trough-like extension 19, in which is adjustably mounted a nut 18 carrying a screw 17 with a block 16 thereon, which forms a stop for the end of the drill. The sleeve 7 carries a cam 11 engaging a roller 12 carried by a part 14 secured to the pivot; the cam may have two rises, so that continued rotation of the drill causes both cutting-edges to be ground. In operation, the hand-wheel is rotated, the cam being held up to the roller by hand-pressure or by a spring or weight, and the engagement of the cam with the roller causing the drill-holder to rock about the pivot 4, thereby feeding the drill into the grinding-wheel and producing the requisite clearance. In a modification, Figs. 4 and 6, the apparatus comprises a bracket 1 having sides 24 carrying centre points 25, on which is pivoted a shaft 41 having on its underside rack teeth 39 and having slidably keyed on it a rocker frame 5. This frame has a transverse housing 6 carrying the drill-supporting sleeve 7 provided with a flange 29, on which is mounted, so as to be adjustable radially, a V-grooved bracket 27. The sleeve is supported at its rear end in the housing 6 by a bush 36, which is screwed internally to receive a feed-screw 17, in which is slidable a stem 16 carrying a block adapted to contact with the end of the drill; the stem may be secured to the feedscrew 17 by a set-screw, feed being applied by rotation of the feed-screw. The sleeve 7 has teeth 38 formed on its periphery engaging the rack 39, and the rocker frame carries a roller 12 in engagement with a fixed cam 11. In operation, on rotating the sleeve 7, the drill being held in position by hand, the housing 6 moves laterally, through the action of the rack and the teeth 38, and also, through the engagement of the roller with the cam, rocks about the centres 25 to feed the drill into the grinding-wheel 23. The roller is held up to the cam by hand-pressure or by a spring or a weight; the rocker frame may be turned to a vertical position for insertion or removal of a drill. The Provisional Specification describes also a modification of the construction shown in Figs. 4 and 6, in which the shaft carrying the rocker is fixed, the rocker moving, under the action of the cam, around the shaft. In this modification, the cam may be adjustable by screws engaging the back thereof, a stop may be fixed to the shaft to limit the travel of the rocker, and a sheet metal guard may be provided to prevent particles of abrasive material &c. from reaching the moving parts of the apparatus. In a further modification, the lateral movement may be given to the drill carried by a connecting-rod arranged between the drill-rest sleeve and the rocking-shaft supporting the carrier. In the construction of Figs. 1 and 3, the grinding-wheel may be traversed to prevent uneven wear.