GB621087A - Improvements in or relating to feeding-arrangements in twist-drill grinders - Google Patents

Abstract

621,087. Grinding twist drills. STOCKWERKZEUGE UND MASCHINEN VERKAUFS-AKT.-GES., and RAUSSER & CIE. Jan. 3, 1947, No. 250. Convention date, Jan. 4, 1946. [Class 60] A manually - operated drill - feeding arrangement for a twist-drill grinder comprises a primary feed adapted to bring the drill into contact with the grinding wheel, and a multi-stage fine adjustment feed adapted to advance the drill in a series of consecutive steps of predetermined stroke. A twist-drill 2 is gripped in a clamping member 8 of a holder 7 adjustable in any direction and carried on a boss 9 having forked legs 31, 32, Fig. 6, engaging therebetween a square grinding rod 34 secured to a casing 13 of the grinding machine and parallel to the axis of rotation of a cup grinding wheel 1 rockable in a plane perpendicular to its axis of rotation. The boss 9 is secured to a mandrel 10, Fig. 4, parallel to the axis of rotation of the cup grinding wheel, and displaceable in a sleeve 11 secured to the grinder casing 13. For a primary feed of the twist drill the mandrel 10 is moved axially in the sleeve 11 by the rotation, by a hand-wheel 16, of a threaded spindle 15 engaging a threaded bore 14 in the mandrel, the spindle 15 having a shoulder engaging an anti-friction bearing 18, and a spring 25 urging the mandrel into engagement with the spindle 15. The multi-stage fine adjustment means includes a socket 20 rotatable but not axially displaceable in the sleeve 11 and having secured thereto a face cam 21 which engages a follower pin 24 secured in an axially slidable bush 17 housing the bearing 18, so that, as a handlever 22 secured to the socket 20 is turned through 90 degrees in four stages, the mandrel 10 is given four axial feed movements, a spring-loaded pin 28 co-acting with four indentations in the socket 20.