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Wire EDM control circuit for rough and finished machining

  • US 4,614,854 A
  • Filed: 05/22/1984
  • Issued: 09/30/1986
  • Est. Priority Date: 11/15/1982
  • Status: Expired due to Term
First Claim
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1. An electric discharge machining control circuit comprising:

  • a pulse oscillation control circuit means for generating a pulse stream;

    an electric discharge machining circuit having a variable circuit constant, operatively connected to said pulse oscillation control circuit means, including a capacitor, a switching means operatively connected to said capacitor which switching means is turned on and off in response to said pulse stream for said pulse oscillation control circuit means for applying a discharge current between a wire electrode and a workpiece in accordance with the variable cicuit constant;

    a short-circuit detector means, operatively connected to said electric discharge machining circuit, for comparing a machining voltage between the wire electrode and the workpiece with a reference voltage and for detecting a short circuit between the wire electrode and the workpiece;

    gate means, operatively connected to said pulse oscillation control circuit means, for inhibiting generation of said pulse stream in response to said short-circuit detector detecting a short-circuit;

    receiving means for receiving a second cut instruction;

    average machining voltage switching means, operatively connected to said receiving means, for decreasing an average machining voltage applied between the wire electrode and the workpiece in response to said second cut instruction, by changing a value of said variable circuit constant from that employed during rough machining;

    reference voltage switching means, operatively connected to said receiving means, for generating the reference voltage applied to said short-circuit detector means, and for decreasing the reference voltage applied to the short-circuit detector means in response to said second cut instruction from a value applied during rough machining to a lower value such that errors in said detecting of a short circuit are prevented.

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