Electric discharge machine with output power control

• US 6,806,434 B1
• Filed: 11/22/2002
• Issued: 10/19/2004
• Est. Priority Date: 05/26/2000
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Suzuki, Akihiro, Hashimoto, Takashi, Hayashi, Hideaki, Iwata, Akihiko, Taneda, Atsushi, Tsunoda, Yoshikazu
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US10/296,329
• Time in Patent Office: 697 Days
• Field of Search: 219/69.13, 219/69.18, 219/130.33
• US Class Current: 219/69.13
• CPC Class Codes: B23H 1/022 for shaping the discharge pulse train B23H1/024 takes precedence
• CPC Class Codes: B23H 2300/22 Circuits using or taking into account line impedance to shape the discharge pulse

Abstract

An electric discharge machine in which electric power for working is supplied between an electrode and workpiece by an electric power unit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine having a voltage detector for detecting output voltage V of a DC electric power source of the electric power unit; a current detector for detecting output current I of the DC electric power source of the electric power unit; a calculator for calculating product V·I of V and I; and a controller for controlling output electric power of the electric power unit to be constant on the basis of a difference between a working command signal for giving a predetermined electric power command and V·I. Even when load impedance fluctuates, it is possible to suppress the fluctuation of electric discharge power, so that surface roughness on a machined face of the workpiece can be made uniform.

Claims

1. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

an electric power detecting means for detecting output electric power of the high frequency electric power unit, including voltage detecting means and current detecting means;

a control means for controlling output electric power of the high frequency electric power unit to be constant on the basis of a difference between a machining command signal for giving a predetermined electric power command and an electric power detection value detected by the electric power detecting means; and

wherein said voltage detecting means and said current detecting means are arranged between an output of said high frequency electric power unit and said matching circuit.

3. An electric discharge machine according to claim 1 or 2, the electric power detecting means including:

a voltage detecting means;

an electric current detecting means; and

a calculating means for calculating the product of a voltage detection value detected by the voltage detecting means and a current detection value detected by the current detecting means.

2. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

an electric power detecting means for detecting output electric power of DC electric power source of the high frequency electric power unit, including voltage detecting means and current detecting means;

a control means for controlling output electric power of the DC electric power source to be constant on the basis of a difference between a machining command signal for giving a predetermined electric power command and an electric power detection value detected by the electric power detecting means; and

wherein said voltage detecting means and said current detecting means are arranged between an output of said high frequency electric power unit and said matching circuit.

4. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

a voltage detecting means for detecting output voltage V of the high frequency electric power unit;

a current detecting means for detecting output current I of the high frequency electric power unit;

a calculation means for calculating α

·

V+β

·

I where V is an output voltage detected by the voltage detection means, I is an output current detected by the current detection means and α and

β

are predetermined coefficients; and

a control means for controlling α

·

V+β

·

I, which is an output of the high frequency electric power unit, to be constant on the basis of a difference between the predetermined working command signal and the calculation value of the calculation means.

6. An electric discharge machine according to claim 4 or 5, further comprising an adjusting means for adjusting values of both coefficients α

and β

or adjusting one of coefficients α and

β

.

5. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

a voltage detecting means for detecting output voltage V of the DC electric power source of the high frequency electric power unit;

a current detecting means for detecting output current I of the DC electric power source of the high frequency electric power unit;

a calculation means for calculating α

·

V+β

·

I where V is an output voltage detected by the voltage detection means, I is an output current detected by the current detection means and α and

β

are predetermined coefficients; and

a control means for controlling α

·

V+β

·

I, which is an output of the DC electric power source, to be constant on the basis of a difference between the predetermined working command signal and the calculation value of the calculation means.

7. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

an electric power detecting means for detecting output electric power of the high frequency electric power unit, including voltage detecting means and current detecting means;

a control means for controlling output electric power of the high frequency electric power unit to be constant on the basis of a difference between a machining command signal for giving a predetermined electric power command and an electric power detection value detected by the electric power detecting means;

wherein said voltage detecting means and said current detecting means are arranged between an output of said high frequency electric power unit and said matching circuit; and

a resistor connected in parallel with the poles.

8. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

an electric power detecting means for detecting output electric power of the high frequency electric power unit;

a resistor connected in parallel with the poles;

a loss detection means for detecting a loss caused by the resistor arranged between the poles;

a calculation means for finding a difference between the output electric power detected by the electric power detection means and the loss detected by the loss detection means; and

a control means for controlling a difference between the output electric power of the high frequency electric power unit and the loss caused by the resistor arranged between the poles on the basis of the working command signal for giving a predetermined electric power command and also on the basis of the calculation value of the calculation means.

9. An electric discharge machine in which high frequency electric power is supplied between poles of an electrode and workpiece by a high frequency electric power unit composed of a DC electric power source, oscillator and amplifier and impedance is adjusted by a matching circuit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine comprising:

an electric power detecting means for detecting output electric power of the DC electric power source of the high frequency electric power unit;

a resistor connected in parallel with the poles;

a loss detection means for detecting a loss caused by the resistor arranged between the poles;

a calculation means for finding a difference between the output electric power detected by the electric power detection means and the loss detected by the loss detection means; and

a control means for controlling a difference between the output electric power of the DC electric power source of the high frequency electric power unit and the loss caused by the resistor arranged between the poles to be constant on the basis of the working command signal for giving a predetermined electric power command and also on the basis of the calculation value of the calculation means.