GB802408A - Improved feed mechanism for grinding machines - Google Patents

Abstract

802,408. Grinding-machines. LANDIS TOOL CO. Oct. 16, 1956 [Feb. 2, 1956], No. 31401/56. Class 60. A feed mechanism for a grinding machine comprises a grinding wheel support 11, Fig. 1, slidably mounted on a base 10, means for actuating a sliding rack 26 to effect movement of the support, a manually-operable shaft 21 which is disposed in the support and carries a pinion 25 engaging the rack, and, mounted parallel to the rack 26 and also engaging the pinion 25, a second rack 27 urged by fluid pressure means in the opposite direction to the feeding movement of the first rack to eliminate backlash between the pinion 25 and the first rack. The rack 26, which is slidably mounted in the base 10, is urged to the left during a feed movement by a piston 28, Fig. 4, in a cylinder 30 and imparts a transverse movement to the pinion 25 and shaft 21 which are then held against rotation in the support 11 and convey the feed movement to the support 11 and a grinding wheel 12. The second rack 27 is also urged in the opposite direction to the feed direction of the first rack to eliminate backlash between the first rack and the pinion by fluid pressure from a pump 40, Fig. 1, and a regulator 42 acting in a cylinder 36 on a piston 35 formed on one end of the rack 27. Projecting from the rack 27 is an arm 71 which co-operates with a rod 69 to rotate bell-crank levers 67, 68 about their pivots 65, 66 during movement of the rack. Attached to the other arms of the levers is a bar 60 which moves in a vertical direction during the feed movement and urges a rod 52 disposed in a bore 53 in the shaft 21 to actuate a position-indicator 50 mounted on the support 11. The support 11 is manuallyadjustable on the base 10 without actuating the indicator 50 by a handwheel 20 which rotates the shaft 21 to move the pinion along the racks ; since the racks remain stationary, no movement is imparted to the bar 60 to actuate the indicator 50. A slow feed towards the end of the normal feed is provided by the rack 26, by means of a pin 80 which is disposed in the rack 26 and engages a pivoted lever 81 ; impact between the pin and the lever is cushioned by a cushioning valve 87 connected to the lever by a rod 85. The lever 81 then presses a roller 90, which is flexibly connected to a piston 93, against a face 112 of a pivoted member 110 to urge the roller downward until the piston 93 contacts a stop pin 101 to operate a limit switch 100 ; the downward speed of the roller, which is varied by the inclination of the face 112, governs the slow rate of feed.