Patent GB-491470-A (GB)
Title: Improvements in and relating to oscillating grinders
IPC: B60T15/04
Filed: 1937-07-30
Abstract: 491,470. Grinding ball races &c. VAN NORMAN MACHINE TOOL CO. July 30, 1937, No. 21123. Convention date, Aug. 12, 1936. [Class 60] A machine for grinding ball bearing races &c., and having the work mounted in a rotating chuck carried by an oscillating head, has the grinding-wheel moved into and out of operative position by two movements, one parallel to, and the other at right-angles to the axis of the wheel, the two movements being produced by a single source of power operating automatically; the wheel also is fed into the work when in operative position under control of gauge mechanism, which operates, when the work has reached a predetermined size, to stop the feed and start a time delay relay and also to cut off the supply of cooling fluid, dry grinding then proceeding for a predetermined period until the work is to size, when the wheel is withdrawn from the work. The machine comprises a frame 20 in which is a vertical shaft 21 having at its upper end a head 22 carrying, on a cross slide 23, a work head 24 in which is rotatably mounted a chuck 25 carrying the work w, the head being oscillated from a shaft 31 by crank mechanism 28-30 ; the head also carries gauge mechanism 26 having a contact point 27. On ways 35, 36 on the frame is a main slide 37 having thereon on ways 38, a cross slide 39 carrying the grinding- wheel 41 driven by an electric motor 42 ; the slide 37 is moved to the left, Fig. 5, and the slide 39 is moved rearwards to carry the wheel 41 into grinding position. On the lower part of the slide 37 is mounted, in a slideway, a slide 46 movable by a stud 48 adjustably engaged by a screw 53 with a link 50, the link being pivoted at 55 to an arm 56 carried by a shaft 57, which is driven 180‹ in either direction to move the wheel 41 into and out of operative position, through gearing 59, 60, by a reversible motor 62 ; the slide 37 is moved to the right by contact of the slide 46 with a plate 65 on the slide 37, and is moved to the left through a spring 66, its movement being stopped by contact of a screw 69 with an abutment 71 on the frame 20. The cross slide 39 is given a slow feeding movement during grinding by a ratchet head 75 and a rapid movement into and out of operative position, and for this purpose, the ratchet shaft 76 is slidably keyed in a sleeve portion 78 of a composite shaft having a screwed part 79 engaging a nut 82 on the slide, so that rotation of the shaft gives the slide the slow feeding movement; the shaft also has a stop portion 80. The slide is urged to the left, Fig. 12, by a spring 85 and its movement to inoperative position is limited by a thumb nut adjustable on a screw in the cross slide and adapted to contact with a bracket on the slide 37. Slidable on the sleeve 78 is a flanged sleeve 95 pressed by a spring 100, the slide 39 being moved into operative position by movement of the sleeve 95 and its position determined by contact of the portion 80 of the composite shaft with an adjustable stop 101. The sleeve 95 is moved by a bell crank lever 110, pivoted to the slide 37 at 111 and having its lower end curved so that it will lie under a ledge 113 on an arm 114 pivoted to the frame 20 at 115, the arm normally being held clear of the lever 110 by a spring 116, and tilted by an arm on the shaft 57, this latter operation occurring when the main slide has stopped in operative position, and causing the cross slide also to be moved into operative position, after which the motor 62 is stopped. The electrical control means is shown diagrammatically in Fig. 21, the power being derived from a transformer 126, the secondary of which is divided to give a section 127 of low voltage for operating the gauge mechanism 26, the full voltage being used for operating the various switches. When the machine is to be started, a handle 130 is depressed, so as to hold down a sleeve 134, Fig. 17, movable vertically by a spring 143 in a bracket 132 on the slide 37, thereby bringing a pawl 138 into engagement with the feed ratchet 139, the pawl being carried by a rod 135 slidable in the sleeve 134 and actuated periodically by a plate 141 moved by a cam 142 on shaft 31 ; when the sleeve rises a member 144 moves the pawl to inoperative position. The sleeve 134 is held down by a detent 143 on a handle 146 which also may be moved by a solenoid 180. Downward movement of the arm also closes switches 152, 153, 155 and opens a switch 156, and vice versa, starting the motor 62, and causing the slides 37, 39 to move to operative position until an arm on the shaft, 57 opens switch 164 and closes a switch 161, stopping the motor 62 and starting the motor for oscillating the head 24. This operation continues until a gauge contact 173 closes and through a solenoid 176 stops the flow of cooling fluid to the work, dry grinding proceeding for a short time, when the gauge contact 160 is closed. This energizes solenoid 180, lifting the handle 146 and stopping the feed of the wheel 41 ; it also opens switches 152, 153, 155 and closes switch 156, thereby closing the circuit of the time delay relay 182. After grinding for the time governed by the relay, this opens switches 175, 186 and closes a switch 187, whereby the flow of cooling fluid is again started and by a solenoid 188 causes the movement of the motor in reverse direction to withdraw the wheel 41 from the work. When the slides 37, 39 have been retracted, an arm on shaft 57 closes a switch 192 and opens a switch 189, the switch 189 stopping the motor 62, and the switch 192 closing the circuit of a solenoid 193, which moves a lever 195 so that it is engaged by a lug on shaft 31, whereby when the shaft reaches a desired angular position the lug operates on lever 195 to open a switch 162 and stop the motor oscillating the head 24, a brake serving to stop the head in desired position by the time delay relay. Other manually operated switches are provided for stopping or controlling the movements of the various parts of the machine.