Patent GB-519386-A (GB)
Title: Improvements in or relating to workpiece actuating mechanism for use in machine tools such as lathes or like machines
IPC: B23B31/26
Filed: 1938-10-20
Abstract: 519,386. Electric motor control systems. CINCINNATI GRINDERS, Inc. Oct. 20, 1938, No. 30366. Convention date, Oct. 20, 1937. [Class 38 (iii)] [Also in Group XXII] Centre lathes &c., wherein the means for driving the work must be disposed in predetermined angular position thereto prior to engagement therewith, have means for presenting work pieces in succession in a definite angular position and in the line of centres and for then moving the driving means into engagement therewith the spindle having previously been stopped in the required angular position. The work is brought downwards into the line of centres by a jack 16 closing a switch 47, Fig. 6. Pressure in a cylinder 30 is reversed by valve means (not shown) and centre 14 and driving pins 12 are advanced into engagement with the work. The pins are advanced by springs 24, Fig. 4, and retracted by a flange 26, on a collet carrying the centre, engaging projections 25 on the pins. On advance of the centre a switch 49 is closed and the lathe is ready for starting by a push button 54, closing the relay coil of a switch 55, which closes a maintaining circuit at 59 and operates a relay switch 61, breaking the circuit of a solenoid 43 at 64 and closing that of a solenoid 35, causing the withdrawal of a bolt 33 from a notch 34 in the flange of the driving pulley. The solenoid-cores are linked together at 45 and act through a bell-crank 37 on a sleeve 38 connected to the bolt by a pin.and slot 41 and spring 40 so that on reverse operation to engage the bolt, this can ride on the flange under spring pressure until the notch is in position. At the same time a switch 68 is closed and a relay switch 70 operates causing a solenoid to remove a roller 77 from contact with a cam 78 and close a switch 80, thus actuating a relay coil 82 actuating the starting switch 83 for the three phase driving motor 23, having a permanent connection at 89 to one phase 87 of the supply. The other phases 86 and 88 are connected respectively to contacts 91 and 94 of the starting switch and of a reverse swich 117. After the machining operation has been completed a member 104 connected to the tool slide closes a switch 103 energizing relay coils 103<1> and 106, closing switch 105' establishing a holding-circuit for these relay coils through switch 68. The relay 106 opens switch 62 breaking circuit to relay coils 61, 55 and 70. De-energization of 55 opens switch 58 and breaks its own holding circuit, of 70 opens switch 71 breaking solenoid circuit 73 allowing a spring to return roller 77 into engagement with cam 78, and of 61 cuts out solenoid 35 and cuts in solenoid 43 urging plunger 33 into contact with periphery of notched flange. If the roller 77 engages one of the lobes 108 of the cam the switch 80 does not open and the motor runs until the roller drops into a part 110 of the cam. The switch 80 now opens and releases the starting switch 83, closing a circuit at 84 and 113 through the relay 116 of the motor reversing switch 117. The contacts 113 are closed by a zero speed switch 115 driven through a viscous clutch for example as described in USA. Specification 1,677,008. This momentary closing of the reversing switch brakes the motor and the spring 119 opens the switch when the speed drops. At the same time the reversing switch closes contacts 125, energizing relay coil 128 and closing switch 101 having a maintaining circuit at 129. The switch 101 thus remains closed after the switch 117 opens. The switch 115 now closes contacts 120 closing the circuit again through the starter switch relay coil. Contacts 96 are closed by the starter switch completing a circuit through contacts 100 closed by the switch 101 to a relay coil 102 opening a switch 115 and making a second break in the circuit to the reverse relay coil 116 so that the reverse switch does not close a second time when the zero speed switch moves over again. The motor is now rotating sufficiently slowly for the bolt to enter the notch in the flange opening the switch 68 and breaking the circuits to relays 102, 128 and 103<1> and allowing the switch members thereof to return to starting position. The spindle is now locked in the required angular position for the replacement of the finished work by a fresh piece.