| 摘要 |
927,447. Control of A.C. motors. SENECA FALLS MACHINE CO. June 9, 1961 [June 16, 1960], No. 20961/61. Class 38 (3). The rotatable work-table of a machine tool is driven to predetermined positions by an electric motor 2 through a mechanical amplifier 3 associated with a pilot motor M for rotating the output shaft of the amplifier at different speeds. Closure of switch 35 energizes relay 31 to connect drive signal generator 18 to signal amplifier 15 whereby the motor M causes the table to be driven towards a stopping position at a high speed. When a cam member on the table engages actuator 33, switch 32 opens to de-energize the relay 31 and disconnect the drive signal generator 18, whilst connecting a transducer 20 to the amplifier 15 for providing low-speed operation of the table. The transducer 20 comprises primary coil 21 and opposed secondary coils 23 associated with a movable core 24 coupled with a spring-biased stylus 25 adapted to engage the surface of the cam carried on the table. As the core 24 is moved towards its null position, the control signal is reduced gradually to zero, whereupon the table stops and relay 49 actuates a signal circuit. If the table moves through its predetermined stopping position, the stylus 25 is driven beyond its null position causing the drive to reverse and return the table to the precise index station. For manual operation, switch 34 is opened to de-energize relay 31, start switch 44 is closed to energize motor 2, and the table moves towards the next station at a lowspeed. The table carries a plurality of cam members, each being adjustable and removable so that the positions of the index stations thereby defined may be adjusted. Specifications 686,650, 691,897 and 692,173 are referred to. |
