Claims
- 1. An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece opposed via a dielectric fluid made of water and a compound or via oil to generate a discharge to machine the workpiece with the energy of said discharge, comprising:
- a tar build-up detector for detecting the build-up of tar on at least one of the electrode or the workpiece based upon a difference between a machining gap impedance found from dielectric fluid resistivity and an electrode area and said machining gap impedance actually measured.
- 2. A method for controlling the application of pulsed voltage to a machining gap formed between an electrode and a workpiece disposed opposite thereto via an insulating dielectric fluid, to generate a discharge operative to machine the workpiece with the energy of said discharge, the method including steps of:
- providing a positive polarity voltage and an opposite polarity voltage from a power source;
- switchably connecting a first current limiting impedance for the opposite polarity voltage between said workpiece and said power source;
- switchably connecting a second current limiting impedance for the positive polarity voltage between said workpiece and said power source;
- applying the positive polarity voltage at the stop time of the opposite polarity pulsed voltage to set the average voltage to a predetermined value;
- detecting a buildup of tar on at least one of said electrode and said workpiece based upon a difference between a machining gap impedance found from dielectric fluid resistivity and an electrode area and a machining gap impedance actually measured.
- 3. The method as set forth in claim 2 further comprising after said tar detecting step;
- increasing the opposite polarity voltage stop time and dropping the average voltage so that tar floats in said dielectric fluid; and
- flowing said floating tar away from said machining gap area.
Priority Claims (1)
Number |
Date |
Country |
Kind |
5-162725 |
Jun 1993 |
JPX |
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Parent Case Info
This is a divisional of application Ser. No. 08/267,233, filed Jun. 29, 1994, now U.S. Pat. No. 5,753,882.
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Divisions (1)
|
Number |
Date |
Country |
Parent |
267233 |
Jun 1994 |
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