GB864779A - Improvements in or relating to grinding machines - Google Patents

Abstract

864,779. Grinding. LANDIS TOOL CO. April 2, 1958 [April 5, 1957], No. 10542/58. Class 60. A feed mechanism for a grinding machine having a support 12, Fig. 1, for a workpiece W, a movable support 11 for a grinding wheel 13, and a sizing device 30 for the work, comprises means for advancing the wheel support through a predetermined initial distance, means for further advancing the wheel support firstly by coarse and then by fine increments to grind the work to the required size as determined by the sizing device, and means actuated by the sizing device for reversing the advancing means to retract the wheel support and for reversing the means for further advancing the wheel support. The grinding wheel support 11 is movable towards and away from the workpiece on guideways on the machine bed 10 either by a handwheel 81 on a shaft 80 connected by a chain 83 to a shaft 85, in turn, connected by gears 86, 87 to a shaft 60 having a worm 61, Fig. 5, engaging a wheel 62 on a lead screw 40 co-operating with a nut 41 secured to the support 11 or by a motor 89, Fig. 1, connected by gears to the shaft 60. The support is also movable under the control of relay-operated, solenoid-controlled valves automatically and successively rapidly by a piston- and-cylinder device 50, 51, Fig. 5, axially moving the lead screw, at a slower but still fast speed by a piston-and-cylinder device 63, 64 axially moving the shaft 60 to rotate the lead screw for a preliminary fast grinding feed to within, say 0À001 inch of the finished size of the workpiece, in coarse increments by the reciprocation of a piston 111 having a pawl 110 engaging a ratchet 100 on the shaft 80, on which is the handwheel 81, and in fine increments by the reciprocation of a piston 104 having a pawl 103 also engaging the ratchet on the shaft 80. The successive movements are controlled by limit switches 1LS and 38LS operated by the ends of the lead screw and shaft 60, respectively, and the number of coarse increments is controlled by a counter actuated each time the piston 111 is operated. A time dwell to allow " spark out " of the wheel is permitted after the preliminary fast grinding and between each of the coarse and fine increments, the fine increments continuing until the workpiece is to size as determined by the sizing device represented by a caliper 30 which actuates a switch to operate a valve 90 and supply fluid to the opposite end of the cylinder 50, to a fast return cylinder 70 to reposition the shaft 60, and to a piston 121 having a pawl 120 which engages a ratchet 101 also on the shaft 80 adjacent the ratchet 100 and is operated the same number of times as the coarse piston 111 and pawl 110. Shuttle valves may be used for the incremental feeds in place of the pawl-andratchet mechanisms. The arrangement provides for the compensation of the reduction in material of the wheel from wear and trueing.