| 摘要 |
PCT No. PCT/CH85/00103 Sec. 371 Date Apr. 7, 1986 Sec. 102(e) Date Apr. 7, 1986 PCT Filed Jun. 27, 1985 PCT Pub. No. WO86/00249 PCT Pub. Date Jan. 16, 1986.An electrical discharge machining circuit with preignition circuitry including a step up transformer and a zener diode to provide preignition pulses (having a higher voltage but lower energy than erosive pulses) prior to erosive pulses. Additionally a resistor and a second zener diode are placed in series to each other and in parallel to the machining gap to limit the voltage of the preignition pulses. Alternative embodiments teach using a preignition control transistor associated with a variable resistor to control the maximum value of the current in the preignition pulses and using an indicator such as an electronic voltmeter, an oscilloscope, or a lamp with the preignition circuitry. |
