Patent GB-604425-A (GB)
Title: Improvements in or relating to sizing machines
IPC: B24B41/06
Filed: 1940-02-13
Abstract: 604,425. Gauging - devices. BRYANT CHUCKING GRINDER CO. Feb. 13, 1940, No. 2785. Convention date, Feb. 10, 1939. [Class 83 (iii)] [Also in Groups XXIII and XXXV] Relates to gauging devices for automatic machines and is described with refer. ence to grinding-machines for internal grinding and consists in automatic elec. tric control means for the size controlling means for each piece in accordance with a gauged dimension of a previously finished piece As applied to a single spindle machine, the finished piece 101 is placed on a tape plug gauge 100, Fig. 2, down which it descends, to an extent depending on the diameter of the bore, depressing a block 103 carrying a sliding contact 110 over a rheostat 111, breaking a contact 117, 118 and making contact 117, 120. A standard piece S, Fig. 9, is mounted on a similar gauge containing rheostat 125, but without contacts such as 119, 120, and the rheostats 111, 125 are joined in bridge formation with rheostats 126 and 76; the bridge being supplied with low potential at 133, 134. The rheostat 76 is controlled by a member 71, Fig. 4, traversed by a screw 74 on a shaft 24 that drives through a clutch 39 a sleeve 23 transmitting through wormgearing 22 and planetary gearing 18, Fig. 5, to a flanged hub 12 driving the feed nut 8 for adjusting the position of the grinding wheel relatively to the work. The planet wheels are carried by a disk 11 loose on the hub 12 and operable either by hand or through wheel 26 for the normal feed. Before the work 101 is placed on the gauge, current passes from the line 133 through contact 118, line 132 and coil 136 to the line 134. Switch 137, 138 is thus closed. On the closing of the switch 138 a holding circuit for the coil 136 is closed through the ammeter contacts 131 since due to the absence of work in the gauge 100 the bridge is unbalanced. On the placing of undersize work on the gauge the contact is broken at 118 and made at 120 completing circuit through the coil 140 and switch 137. If the piece 101 is sufficiently undersize, the bridge circuit remains unbalanced maintaining the holding circuit for the coil 136 and switch 137. The switch 145 then closes so that solenoid 62 swings lever 50, Fig. 4, against spring 54 shifting gear 32 into mesh with gear 35 and closing clutch 39. The gears 37, 35 are driven in reverse directions by crossed and open belts 43, 42 from the main driving shaft. The feed screw 7 is thus actuated to apply cut until the consequent movement of the sliding contact 75, Fig. 4, balances the bridge circuit and breaks the contact at 131. The switches 137, 138 then open causing the opening of the switch 145 and the spring 54 throws over the clutch to the left in Fig. 4, stopping the infeed of the grinding-wheel and reversing the rotation of the shaft 24 to return the member 71 to its initial position when abutment 70 strikes rod 65 and shifts the gear 32 into neutral. The gauged work-piece is then removed and the bridge circuits revert to their original condition. In a modification applied to the multiple spindle work turret machine described in Specification 518,914, [Group XXXV], the gauging is automatically performed, in conjunction with the removal of the finished piece and the supply of a fresh blank from a shoot 340, Fig. 17, by means of a plunger 325 on a sliding carriage 326 operated by a piston-rod 335 under the control of valves operated by the machine cam-shaft. A head 300 on the plunger 325 is entered into the finished work to remove it from the chuck and a hardened abutment 305, Fig. 19, on a lever 304 passes through slot 303 in the head to engage the bore of the work. The lever has a spring fulcrum 307 and its normal position is determined by a spring 306 and stop-screw 311. In this position the other end of the lever which is of magnetic material is so positioned between coils 313 that an inductance bridge circuit, Fig. 26, is balanced. If the bore of the piece be undersize then the lever is deflected and the balance is upset and the needle 433, Fig. 26, of a micro-ammeter swings over to make contact at 434. The bridge circuit with the coils 313 is completed by the coils 406, 407 of a " differential " transformer and potential from a transformer 402 is applied across the common terminal 424 of the transformer 405 and the mid-point of the coils 313 through the sliding contact 416 of a potentiometer 417, the circuit through the potentiometer being completed by a connection to the lead between the coil 406 and the coils 313. The terminal 424 is also connected to a sliding contact 422 of a rheostat 420 conconnected across the other ends of the transformer coils 406, 407. The ends of the rheostat 420 are also connected through a fullwave rectifier 427 with the ammeter. The potentiometer provides a zero adjustment. At the proper time in the machine cycle a cam 476 on the main cam-shaft 235 closes contacts 477 rendering the gauging mechanism operative through a low-voltage supply at 430,431, a coil 438 closing switches 436,440. If the work be undersize a holding circuit 432,435 is established for the coil 438 through the switch 436 independent of the contacts 477. The switch 440 establishes a circuit for the coil 444, including contacts 317, Fig. 19, closed due to the presence of the work, and a switch 450 is closed applying a higher voltage supply at 452, to a solenoid 454 operating a valve 458 to admit pressure below a piston 460 and rock a lever 257 to cause infeed of the grinding wheel that applies the sizing cut. The piston-rod carries the sliding contact 422 and as soon as the bridge circuit becomes sufficiently balanced the ammeter needle 433 swings back breaking the holding circuit for the coil 438 and causing the switches 436,440 and 450 to open. Spring 470 then closes the valve 458 and the infeed is stopped and the piston 460 returns to its initial position. The contacts 317 prevent the gauging and sizing mechanism from operating unless a work-piece is in position. After gauging, the plunger 325 retracts and the work is stripped from the head 300 by fingers 348, Fig. 17, and passes into the discharge shoot 350. On further retraction of the plunger, a pin 347 contacts a lever 346 rocking an arm 344 so that a pin 342 releases the bottom blank in the shoot and a pin 341 holds up the remainder. A fresh advance of the plunger causes the head 300 to remove the liberated blank from the shoot and insert it into the chuck. The indexing of the turret, the trueing of the grinding wheels, and the mounting of the wheel heads are substantially as described in the prior Specification. The operation of the eccentric 222, Fig. 12, by a piston 226 to apply and remove the cut is also as before but the actuation at 220 to compensate for wheel wear is modified. The threaded sleeve 242 is held against axial movement by a ball thrust bearing 544 held in place by the frame member 243, and is rotated by a gear 245 driven through pinions 246,248 by a ratchet wheel 249, Fig. 14. Two levers 252 are loose on the shaft 250, one on each side of the wheel 249, are connected by a pin 253, and are counter-weighted at 275. A block 254 carrying the pawl 270 is pivoted on the pin 253 and the amount of movement is adjustable by screws 271,272. A pin 256 engages a fork in the block and this pin is carried by one arm of the two-armed lever 257  the other arm of which carries a roller 262 that is actuated by a cam 263 brought into operative relation at the required time by the axial movement of the turret. The lever 257 is also actuated by the gauging mechanism as described above. The machine illustrated forms the subject-matter of Specification 518,914, [Group XXXV].