Patent GB-626643-A (GB)
Title: Grinding wheel feeding mechanism
IPC: B24B47/20
Filed: 1946-05-29
Abstract: 626,643. Hydraulically-operated grinding-machines. NORTON CO. May 29, 1946, No, 16307. Convention date, July 28, 1945. [Class 60] [Also in Group XXIX] A grinding-machine having a rotatable grinding wheel and a transversely movable slide therefor comprises means including a piston and cylinder rapidly to move said slide, means including a dash pot feed regulator to slow down the rapid approaching to a relatively slow continuous feeding movement, electrical control means rendered operative after a predetermined slow feed to produce a fine intermittent feed, means to stop the forward feed, and a time delay relay operatively connected to return said slide and grinding wheel to an inoperative position after a predetermined period of dwell. There may be a fine continuous plunge-cut feed before the forward feed is stopped. The grinding wheel slide 22 is moved by a piston 36 working in a cylinder 35 under the control of a valve 43. The sequence of operations is as follows:- 1. Rapid approach of grinding wheel to work. The operator rocks control lever 155 to close push button start switch 157, so energizing relay 160 which energizes solenoid 50 to move valve 43 to the left. The piston 36 moves to the left at a rate determined by the setting of a throttle valve 78 in the exhaust line. 2. Relatively slow continuous feed (shoulder feed). Before the grinding wheel contacts the work, a collar 61 on the rod of the piston 36 engages a sleeve 58 in contact with dashpot pistons 56, 57; the rate of movement is now determined by the setting of a needle valve 64 in the outlet from the dash pot cylinders. 3. Fine intermittent feed (rounding up). When screw 51 carried by the sleeve 58 engages and closes limit switch 52, relays 161, 162 are energized. Relay 161 energizes solenoid 68 to close valve 67, thus stopping further exhaust from the dashpot cylinders through the needle valve 64. Relay 162 energizes solenoid 93 to close valve 92 and also energizes solenoid 131 to open valve 130, thus admitting pressure liquid to a hydraulic reciprocating motor 119 constructed as in Specification 535,227, [Group XXIX] ; the continuous reciprocation of the rod 122 of the motor causes, by tappets 104, 105, intermittent shifting of a valve 101 containing a shuttle valve 102, whereby intermittent exhaust of predetermined amounts of fluid from a cylinder chamber 90 of a cylinder 83 is obtained; the cylinder 83 contains a piston 82 having a rod 81 which is thus withdrawn in steps from a cylinder 80 which receives fluid from the dashpot cylinders. 4. Fine continuous feed (body feed). A gauge head 145 is placed in operative position in engagement with the work piece. When screw 53 carried by the sleeve 58 engages and opens limit switch 54, the relay 162 is de-energized; the solenoid 131 is thus de-energized allowing the valve 130 to close under spring action, to stop the intermittent infeed of the grinding wheel. The solenoid 93 is also de-energized allowing valve 92 to open under spring action; exhaust from the cylinder chamber 90 now passes continuously through the valve 92 and throttle valve 94, the setting of which determines the rate of movement. 5. Dwell (sparking-out or finish). When the work is reduced to predetermined size contacts in the gauge 145 close to energize relay 149; this energizes the solenoid 93 to close the valve 92 and stop the feed, and also initiates action of time delay relay 150. 6. Rapid withdrawal. After predetermined time interval has elapsed, time relay 150 de-energizes relay 160 which deenergizes solenoid 50 whereby valve 43 is moved to the right by a spring; the piston 36 is thus moved rapidly to the right. The dash pot system can be replenished by opening a valve 140.