| 摘要 |
1,175,271. Electro-erosion. ELOX CORP. 18 Jan., 1967 [9 March, 1966], No. 2690/67. Heading B3V. [Also in Division G3] Apparatus for electrically machining a conductive workpiece 12 across a dielectric coolant filled gap between a tool electrode 10 and the workpiece comprises a servo feed system 18, 19 which is arranged to provide a rapid approach of electrode 10 towards the workpiece 12 under gap open circuit conditions, and a rapid withdrawal under prolonged short circuit conditions. When the apparatus is operating normally a relay 46 connected across the gap is energized and the gap conditions are sensed by a diode 20 and a capacitor 22 the voltage across which is compared with a reference signal derived from a circuit including a reference source 24, potentiometers 26, 30, 32, 34, 28 with associated diodes 31, 36, 38, 29 and the closed contacts 40 of relay 46; the resulting signal is applied to the servo system 18, 19 whereby the electrode 10 is moved at a normal speed towards or away from the workpiece 12 in a manner such that gap conditions are maintained at an optimum value. The relay 46 is associated with a circuit including a fourlayer device 54, capacitors 44, 52, resistors 48, 50 and a diode 52, the arrangement being such that the device 54 is rendered conductive to shunt relay 46 when open or short-circuit conditions are present in the gap; thus, under these conditions the contacts 40 open to increase the signal to the servo system 18, 19, whereby the speed of operation of the system is increased in the desired manner. |
