Patent GB-692909-A (GB)
Title: Machine tools
IPC: B21D31/02
Filed: 1951-09-27
Abstract: 692,909. Electric control systems. CELANESE CORPORATION OF AMERICA. Sept. 27, 1951 [Sept. 29, 1950], No. 22592/51. Class 40 (i) [Also in Group XXII] In a machine tool wherein the workpiece is advanced e.g. horizontally between successive contacts of a, e.g. vertically reciprocating tool, which thus contacts the workpiece at a series of spaced contacts, the work holder is moved between successive contacts by a Selsyn system in which in each contact effects a change in the electrical connections of one of the Selsyn elements, the resulting electrical unbalance of the system causing a servomotor to advance the workpiece to its next position to rebalance the system in readiness for the next contact by the tool. The invention is described as applied to the punching of indentations for locating apertures to be subsequently drilled in a jet cup used for spinning multi-filament materials. The indentations are arranged in one, two or three concentric circles under the control of a selector switch, and the angular indentation spacing in the three circles is different and controlled by preset sequence switches to give any one of ten spacings. Punch mechanisms. Fig.. 1. A press, of known type, comprises a ram assembly 29 adapted to be reciprocated continuously by a plunger 28 operated by fluid pressure in a cylinder 25. The ram assembly Figs. 5, 6 (not shown) consists of a block 38 carrying adjustable sleeves 41 slidable within guide tubes 33 secured to a base plate 31 resting on the frame bed 22. The ram also carries slidably mounted thereon a.hold-down element 67 which, as the ram is depressed, resiliently holds the jet cup 75 in position on the anvil 77 while the punch housed within the hold-down moves downward through the hold-down to punch the jet cup, and, upon subsequent upward movement of the ram, is retracted within the hold-down before the latter is raised to release the jet cup. A cross head 127 movable with the ram steps an indexing switch 115 Figs. 7, 8 (not shown through a lever, pawl and ratchet 118. at the bottom of each plunger stroke, and also operates a switch 207 at substantially the same time. The jet cup 75 is carried in a self-centring chuck on an anvil 77, Figs. 3, 4 (not shown), the anvil being carried by a shaft 78 Figs. 9, 10 secured to a turntable 128 rotatable by a servo indexing motor 136 through a shaft 136 and worm gear 137, 138. The turntable 128 carries rigid therewith ring gears 139, 141 with which mesh the rotors ot ten Selsyns 143 a-j mounted on a plate-142, the gear ratios between the ring gears and the individual Selsyns being all different. The turntable assembly 129 is mounted on an upper slide 145 adjustable manually in one horizontal direction by a feed screw 147 rotated by a handle 148, Fig. 9. The slide 145 is carried on a lower slide 149 adjustable horizontally in a direction at right angles to the motion of the upper slide 145 through a feed screw 151 driven through a shaft 153 by a " radial index" servo-motor 154 which at the same time adjusts a potentiometer 162. Angular spacing of indentations; control circuit, Fig. 12. The ten Selsyns 143 a-j, Figs. 9, 10 have their rotors 172 a, b ..... connected in parallel to an A.C. source, while their stators 171 a, b ..... are adapted to be' connected selectively by the operative one of three ten position three wiper switches 163, 175, 183 over contacts of relay coils 317, 315 and the switch 115, to the stator of a reference Selsyn 198. The operative Selsyn 143 a-j having been pre-selected by the operative selector switch, the system is balanced just before the jet cup is punched. At the bottom of the ram stroke, i.e. as punching is effected, the switch 115 is advanced one step to switch the phase connections of the operative Selsyn 143 a-j whereupon the consequential error voltage in rotor 199 operates the servo-motor 135 until balance is restored, the motor 135 at the same time rotating the turntable to a new position in readiness for the next punching stroke of the' ram. The switching of the Selsyn " phase " connections by the switch 115 is sequential and such that the turntable is always moved forward so that a circular row of holes is punched. The angular spacing of the holes may be varied by selecting a different one of the Selsyns 143 a-j by appropriate setting of the operative selector. Three selectors 163, 175, 183 are provided, one for each of the three rows of holes that may be punched, and are switched in circuit by the relays 315, 317 so that different angular spacings of the punchings may be effected in the difference circles of holes. Counter circuit; Fig. 13. The operations of the switch 207, actuated at the same time as the switch 115 by the cross arm 127, Fig. 1, are counted to radix nine on rotary switches 222-223 (units), 239, 241 (nines) and 254 (eighty ones). The bank contacts of these switches are inter-connected with those of three switches 255 263, 271 in such a way that, dependent on the setting of the operative switch 255, 263 or 271, a control impulse is sent to operate a relay 277, Fig. 14, when a predetermined number of punches has been registered by the counter 222, 223...... The numbers in question are tabulated in the Specification. The switches 255, 263, 271 are set in dependence on the angular spacing setting, i.e. according to the operative Selsyn 143 a-j, so that the control impulse is sent to operate the delayed release relay 277 when a complete circle of holes has been punched. Circle selector circuit, Fig. 14. Three potentiometers 332, 333, 334 are provided corresponding to the three circles of holes that may be punched. Normally the potentiometer 332 is connected in a bridge circuit with the potentiometer 162, the bridge being automatically balanced by the servomotor 154 adjusting the potentiometer 162, and at the same time moving the slide 149, Fig. 1, to adjust the turntable. At the appropriate times the potentiometers 333, 334 are switched into the bridge circuit in lieu of potentiometer 332 to cause the bridge balancing motor 154 to adjust the jet cup for punching the second and third row of holes respectively. General operation. The number of rows of holes to be punched. in a jet cup positioned on the anvil are determined by a three-position circle selector switch 294, Fig: 14. Assuming it is set to position c for three rows of holes, then, after the angle spacing selectors 163, 175, 183 and the counter selectors 255, 263, 271 have been set according to the angular spacings desired, a start button 366, Fig. 14, is momentarily depressed to energize a relay 371, which locks and energizes the solenoid-operated valve 349 to admit pressure fluid to the cylinder 25 to start the reciprocations of the ram. The first row potentiometer 332 will have been connected in the bridge circuit at the completion of the previous punching operation, so that the motor 154 will have already positioned the jet cup for punching of the first row of holes. Punching will commence, the angular spacing being determined by the first row angle selector 163, Fig. 12. When the first circle of holes has been punched, the number of holes punched and counted by the switches 222, 239, 254 will be equal to the number to which the first row number selector switch 255 has been set. Accordingly, the relay 277 will be energized over these switches. It zeroises the counter switches and operates a contact 377, Fig. 14, whereby the charge of a condenser 379 operates, over the circle selector switch 294, a relay 322 which locks and connects the second row potentiometer 333 in the bridge circuit in lieu of 332, whereupon the resultant unbalance of the bridge causes the motor 154 to adjust the jet cup for punching of the second row of holes. The bridge output after amplification at 335 is also fed to a relay 397 which de-energizes the valve 349 and so stops the ram-punch reciprocations during this adjustment. The operation of relay 277 also energizes a relay 321, Fig. 14, which energizes a relay 315 to switch the second row angle selector 175, Fig. 12, into circuit with the sequence switch 115 and the reference Selsyn 198, and also switches the second circle number selector 263 into operation. When relay 277 de-energizes, relay 321 relapses and relay 316 energizes. Punching of the second circle of holes in the jet cup now proceeds with the angular. spacing determined by the selector 175. When relay 277 is again energized after punching of the second row, it zeroised the counter switches and over contact 377, Fig. 14, energizes a relay 326 which locks and connects the third row potentiometer 334 in the bridge circuit, whereupon the punch operation is stopped as before until the bridge balancing motor 154 has positioned the jet cup for punching the third row of holes. At the same time the relay 277 again energizes relay 321, Fig. 14, whereupon relay 317 energizes and switches the third angle selector 183, Fig. 12, into circuit with the sequence switch' 115, and also switches the third number selector 271 into operation. As relay 277 relapses, relay 321 releases and relay 318 energizes. Punching of the third row of holes now proceeds, the angular spacing being determined by the third row selector 183, Fig. 12. When relay 277 is again energized after the third row has been punched, the pulse from the condenser 379 over contacts 377 operates a relay 327 which de-energizes relays 322, 326 to connect the first row potentiometer 332 in circuit whereupon the punch is stopped as heretofore while the bridge balancing motor 154 adjusts the anvil carrying the jet cup to the position for punching the first row of holes in the next cup. Where relay 277 relapses, all relays revert to normal in readiness for the punching of the next cup. If only one or two rows of holes are required, the selector 294 is set to position a or b when the relay 319 is energized to stop the punching operation after punching of the firs