| 摘要 |
EDM method and apparatus in which the electrical discharge machining pulses are produced by the application across the machining gap of a succession of time-spaced trains A of discrete elementary pulses a having an on-time tau on and off-time tau off, the trains having a duration Ton and an interval Toff. In a machining process, upon occurrence of an arcing, short-circuiting or excessive gap contamination condition, either of the off-time tau off or the cut-off interval Toff is increased. When the one controlled time tau off or Toff is increased to be greater than a predetermined value, the other, Toff or tau off, is decreased generally inversely proportionally to the increased tau off or Toff. When tau off or Toff is decreased to be smaller than a predetermined level, Toff or tau off are increased. Preferably, the sum of total off-times tau off plus the cut-off interval Toff in a single cycle or period of successive trains A is maintained at a present value so that the mean machining current is maintained constant as desired.
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