GB674718A - Improvements in or relating to surface grinding machines - Google Patents

Abstract

674,718. Grinding. FRYE, J., SELBY, J., and VICTORIA MACHINE TOOL CO., Ltd. Dec. 1, 1950, No. 29498/50. Class 60. In a surface grinding machine the grinding tool is advanced towards or against the work through the medium of a feed screw, which is adapted to be directly rotated by a manually operable member provided thereon, or to be indirectly rotated by another manually operable fine adjustment member through a reduction drive and a coupling device adapted to be adjusted into or out of operation by a control member, the reduction drive comprising a worm element adapted to be rotated by the fine adjustment member, and a single helical toothed gear wheel combined with a coupling disc to form an axially movable combined member which may be moved to engage with or disengage from a complementary coupling member carried by a member mounted on the feed screw. On a base casting 1 is bolted a pedestal 2 the upper end of which carries a radially-extending rotatable head 3; vertically slidable on the pedestal 2 is an arm 4 to which is bolted a casing 5 containing an electric motor 6, the shaft 7 of which carries the grinding member 8. The motor casing 5 carries a pair of spaced radial arms 9 between which is mounted a bar 10 to serve as a hand-grip, whereby the casing 5 may be rotated angularly about the pedestal 2. The lower part of the pedestal 2 is enclosed by a flexible sleeve 22 of leather or the like. Vertical travel of arm 4 on standard 2 is controlled by a feed screw 11 journalled in the head 3 and passing through a screw thread and bore in arm 4. A handwheel 12 is positively keyed to the upper end of the feed screw 11, whereby the screw 11 may be rotated rapidly for coarse adjustment of the grinding member 8 relatively to the surface of work mounted on table 13 on base 1. The feed screw 11 may also be adjusted slowly and accurately by a knob 14 projecting from the side of head 3 and positively mounted on a shaft 15, carrying a worm 16, housed in a sleeve 26 having a longitudinal slot 27 to permit engagement of the worm 16 with a single helical toothed gear 17 slidable along the upper shank portion of feed screw 11 just below the hand wheel 12. The hub of the gear wheel 17 is extended upwardly and has formed integrally therewith a coupling disc 18 having a ring of holes 19 for engagement by a coupling pin 20 extending downwardly from the hub portion of handwheel 12. The hub piece of knob 14 has graduations co-operating with a zero mark on the end portion of sleeve 26. The worm gear 17 is moved up or down, to bring coupling disc 18 into or out of engagement with driving pin 20, by sleeve 26 which is rotatable in arm 4 and carries an operating lever 21. The sleeve 26 is located longitudinally by a retaining pin 28 engaging a circumferential groove 29 in sleeve 26.