JPH11333632A - Electrical discharging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a break of an interelectrode current during discharge of a current and to improve precision of discharge by a method wherein on and after a timing at which the current of a first capacitor element is damped, and a current stored at a second capacitor element between electrodes is caused to flow, and on and after a timing at which a current of the second capacitor element is damped, a current stored at the first capacitor element between the electrodes is caused to flow. SOLUTION: A machining current supply part 4 comprises a DC power source 3; a current control resistor 5; a switching element 6; a switching control part 8 to control the timing of ON/OFF operation of the switching element 6; and a first diode 7. A first inductance element 9 arranged between the first diode 7 and an electrode 1 is connected in series between a DC power source 3 and an electrode 1 - work 2 and a first capacitor element 10 is connected in parallel to the first inductance element 9. Between the first inductance element 9 and the electrode 1, a second inductance element 11 and a second capacitor element 12 are connected in parallel to the DC current power source 3 and the electrode 1 - the work. A second diode element 13 to the machining current feed part 4 is connected in series to a connection point between a second inductance element 11 and the second capacitor element 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining apparatus, and more particularly, to applying a voltage to an electrode and a workpiece to discharge the workpiece by an electric discharge generated between the electrode and the workpiece. The present invention relates to an electric discharge machine for machining.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram of an example of a conventional electric discharge machine. In the electric discharge machine 100, the machining current supply unit 4 supplies a current to the electrode 1 and the workpiece 2. The machining current supply unit 4 includes a DC power supply 3, a current control resistor 5 for controlling a current in the circuit, and an ON / OFF switch at a predetermined timing.
It includes a switching element 6 that performs an OFF operation, a switching control unit 8 that controls timing of ON / OFF operation of the switching element 6 based on a predetermined gate signal (drive signal), and a diode 7.

The machining current supply unit 4 applies a pulse-like current waveform controlled so as to have a desired current peak value to the electrode 1 and the workpiece 2 at the timing of the ON / OFF operation of the switching element 6. Supply. As a result, a discharge is generated between the electrodes 1 and the workpiece 2, and the workpiece 2 can be processed into a desired shape using the discharge.

FIG. 4 shows the timing of the on / off operation of the switching element 6 and the voltage waveform and the current waveform generated between the poles by the on / off operation. FIG.
4A shows a voltage waveform, and FIGS. 4B to 4D show current waveforms. Since the switching element 6 repeats the on / off operation at a predetermined timing, a current having such a waveform repeatedly flows between the poles.

[0005] In the figure, T1 is the timing at which the switching element 6 turns on, T2 is the timing at which the insulation between the electrodes is broken and discharge starts, and T5 is the timing at which the switching element 6 turns off. From timing T2, current starts to flow between the poles. And the timing T
Between 2 and T5, a current having a rectangular current waveform flows between the poles. The pulse width t of this current waveform is determined based on the processing content.

[0006]

However, in the conventional electric discharge machining apparatus 100 described above, the electrode shape is large and the capacitance component formed by the electrode 1 and the workpiece 2 is large, or the capacitor floating on the electrode 1 side. If the component is large, a vibration component is generated immediately after the start of discharge (timing T2), and the current is cut off halfway. If the current is cut off in the middle, as shown in FIG. 4C, a current waveform having a pulse width t cannot be obtained, a current required to maintain discharge cannot be supplied, and electric discharge machining cannot be performed. There's a problem.

When a current having a low peak current flows between the poles, the impedance of the discharge itself fluctuates greatly, so that the current is cut off halfway. If the current is cut off halfway, as shown in FIG. 4D, a current waveform having a pulse width t cannot be obtained, so that a current necessary for maintaining discharge cannot be supplied, and electric discharge machining cannot be performed. There is a problem.

In order to solve such a problem, there is a method in which an inductance element having a large inductance value is inserted into a circuit, and a current having a high peak current flows between the poles. However, if the peak current is high, the time until the current reaches the peak current is delayed, and the current is cut off at the initial stage of discharge. Further, when the peak current is high, particularly in the case of an engraving electric discharge machine in which the electrode shape is transferred to a workpiece, there is a problem that the consumption of the electrode is not negligible.

The present invention has been made in view of the above, and an object of the present invention is to provide an electric discharge machining apparatus capable of preventing interruption of current, reducing electrode wear, and improving machining accuracy.

[0010]

In order to achieve the above object, an electric discharge machining apparatus according to the present invention supplies a current from a DC power supply to an electrode and a workpiece to provide a current between the electrode and the workpiece. Machining current supply means for generating electric discharge; a first inductance element provided in series between the DC power supply and the electrode-workpiece; and a first inductance element provided in parallel with the first inductance element. A capacitor element, a second inductance element and a second capacitor element provided in parallel between the DC power supply and the electrode-workpiece,
The direct-current power supply and a diode element provided in series between the electrode and the workpiece at a connection point between the second inductance element and the second capacitor element.

In the electric discharge machining apparatus according to the present invention, the electric current stored in the first capacitor element rapidly raises the current between the electrodes at the start of the electric discharge, and the electric current between the electrodes is reduced after the time when the current of the first capacitor element is attenuated. The current stored in the first capacitor element flows between the poles after the timing at which the current of the second capacitor element attenuates, so that the current between the poles flows during discharge. It is not interrupted.

[0012] In the electric discharge machining apparatus according to the present invention, in the electric discharge machining apparatus described above, the machining current supply means includes a DC power supply and a resistor provided in series between the electrode and the workpiece. It comprises an element, a diode, and switching control means for controlling the operation of the switching element.

In the electric discharge machining apparatus according to the present invention, a current waveform having a predetermined peak current and a predetermined pulse width can be stably obtained at predetermined intervals.

The electric discharge machine according to the present invention is the electric discharge machine described above, wherein the inductance values of the first inductance element and the second inductance element and the capacitance values of the first capacitor element and the second capacitor element are different from each other. It is variable.

In the electric discharge machine according to the present invention, the inductance values of the first and second inductance elements and the capacitance values of the first and second capacitor elements can be adjusted so that the current is not interrupted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an electric discharge machine according to the present invention will be described below in detail with reference to the drawings.
In the embodiments of the present invention described below,
The same components as those of the above-described conventional example are denoted by the same reference numerals as those of the above-described conventional example, and description thereof is omitted.

FIG. 1 is a circuit diagram of an electric discharge machine according to one embodiment of the present invention. In the electric discharge machine 50, the machining current supply unit 4 is connected via the first inductance element 9, the first capacitor element 10, the second inductance element 11, the second capacitor element 12, and the second diode element 13. To supply current to the electrode 1 and the workpiece 2.

The machining current supply unit 4 includes a DC power supply 3
A current control resistor 5 for controlling a current in the circuit, and a switching element 6 for performing on / off operation at a predetermined timing
A switching controller 8 for controlling the on / off operation timing of the switching element 6 based on a predetermined gate signal; and a first diode 7. As the switching element 6, a MOSFET or another semiconductor element, for example, an electric switch such as an IGBT or a transistor is used.

The first inductance element 9 is connected between the first diode 7 and the electrode 1 by the DC power supply 3.
And the electrode 1 and the workpiece 2 are connected in series. The first capacitor element 10 is connected in parallel with the first inductance element 9. The first inductance element 9 may be formed by wiring inductance of a processing circuit such as a feeder line. The second inductance element 11 and the second capacitor element 12 are connected in parallel between the first inductance element 9 and the electrode 1 and between the DC power supply 3 and the electrode 1 and the workpiece 2. ing.

The first inductance element 9 and the second
As the inductance element 11, an element whose inductance value can be adjusted is used. As the first capacitor element 10 and the second capacitor element 12, those capable of adjusting the capacitance value are used. The second diode element 1
Reference numeral 3 denotes a connection point between the second inductance element 11 and the second capacitor element 12, which is connected in series to the machining current supply unit 4.

The processing current supply section 4 generates a pulse-shaped current waveform controlled to have a desired peak current at the timing of the ON / OFF operation of the switching element 6. This current causes the first capacitor element 10 to start charging. Also, the second capacitor element 12 starts to be charged via the second diode element 13.

FIG. 2 shows the timing of the on / off operation of the switching element 6, and the voltage waveform and the current waveform generated by the on / off operation. It should be noted that FIG.
2 (b) is a current waveform flowing between the poles, FIG. 2 (c) is a current waveform flowing through the first inductance element 9 and the first capacitor element 10, and FIG. d) is a current waveform flowing through the second inductance element 11 and the second capacitor element 12. Since the switching element 6 repeats the ON / OFF operation at a predetermined timing, such a current having such a waveform is applied to the gap, between the first inductance element 9 and the first capacitor element 10, or between the second inductance element 11 and the second Capacitor element 1
It flows repeatedly to 2.

In the figure, T1 is the timing at which the switching element 6 is turned on, T2 is the timing at which the insulation between the electrodes is broken and discharge starts, and T3 is the first capacitor element 1.
A timing at which the current of 0 attenuates, T4 is a timing at which the current of the second capacitor element 12 attenuates, and T5 is a timing at which the switching element 6 turns off. In addition,
The time between timings T1 and T2 is called no-load time,
From timing T2, current starts to flow between the poles.

The timings T2 and T3 as described above
And T4, the inductance values of the first inductance element 9 and the second inductance element 11 and the capacitance values of the first capacitor element 10 and the second capacitor element 12 are adjusted.

At a timing T2, as shown in FIG. 2B, a current starts to flow rapidly from the machining current supply unit 4 to the gap via the first capacitor element 10. This rapid flowing current prevents the current from being cut off halfway due to a vibration component caused by a capacitor component formed on the electrode 1 at the discharge start stage.

Between timings T2 and T3, FIG.
As shown in (c), the current flowing through the first capacitor element 10 attenuates.
The second capacitor element 1 via a diode element 13;
Since the second capacitor element 12 is charged, the second capacitor element 12 starts discharging from the timing T2, as shown in FIG. Then, between the timings T3 and T4, the current of the second capacitor element 12 flows between the poles via the second inductance element 11, so that the current is not interrupted during this time.

At the timing T4, as shown in FIG. 2D, the current flowing through the second capacitor element 12 and the second inductance element 11 attenuates, but as shown in FIG. 1 inductance element 9 and first
Since the current flowing through the capacitor element 10 has reached the peak current, the current does not stop halfway between the timings T4 and T5.

As shown in FIG. 2C, the timing T
Between 2 and T3, the current stored in the first capacitor element 10 rapidly raises the current between the electrodes, so that no current interruption occurs during this time. Further, as shown in FIG. 2D, between the timings T3 and T4, the current mainly stored in the second capacitor element 12 flows between the poles via the second inductance element 11, so that the current No interruptions occur. Then, as shown in FIG. 2 (c), between the timings T4 and T5, a current flows between the poles via the first inductance element 9 and the first capacitor element 10, so that there is no interruption in the current. . As a result, as shown in FIG.
5, the current flows between the poles based on the current waveform having a pulse width t that is almost rectangular. The pulse width t of this current waveform is
Determined based on the processing content.

In the electric discharge machine 50, the timing T
Since there is no interruption of current between T2 and T5, as shown in FIG. 2B, a current based on a current waveform having a pulse width t close to a rectangle flows between the poles, and the workpiece can be precisely moved. It can be processed. Since the current is not interrupted, the consumption of the electrode can be reduced by using a current having a low peak current.

In the above embodiment, the DC power supply 3 supplies the current, but the current may be supplied using an external auxiliary power supply.

[0031]

As can be understood from the above description, according to the electric discharge machining apparatus of the present invention, the electric current stored in the first capacitor element at the start of electric discharge rapidly increases the electric current between the electrodes, and After the timing at which the current of the one capacitor element attenuates, the current stored in the second capacitor element flows between the poles. After the timing at which the current of the second capacitor element decays, the current is stored in the first capacitor element between the poles. Since the current flowing between the electrodes is not interrupted during discharge, the accuracy of electric discharge machining is improved. further,
Even if the peak current is low, the current between the poles is not interrupted. Therefore, the consumption of the electrode can be reduced by using a current having a low peak current.

According to the electric discharge machine according to the next invention,
Since a current waveform having a predetermined peak current and a predetermined pulse width can be stably obtained at predetermined intervals, the accuracy of electric discharge machining is improved.

According to the electric discharge machine according to the next invention,
Since the inductance values of the first inductance element and the second inductance element and the capacitance values of the first capacitor element and the second capacitor element can be adjusted so that the current is not interrupted, the accuracy of electric discharge machining is improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of an electric discharge machine according to the present invention.

FIG. 2 is an explanatory diagram showing a voltage waveform and a current waveform in the electric discharge machine shown in FIG.

FIG. 3 is a circuit diagram showing a schematic configuration of a conventional electric discharge machine.

FIG. 4 is an explanatory view showing a voltage waveform and a current waveform in a conventional electric discharge machine.

[Explanation of symbols]

Reference Signs List 50 electric discharge machine, 1 electrode, 2 workpiece, 3 DC power supply, 4 machining current supply section, 5 current control resistor, 6
Switching element, 7 first diode, 8 switching controller, 9 first inductance element, 10 first
Capacitor element, 11 Second inductance element, 12
Second capacitor element, 13 Second diode element.

Claims (3)

[Claims] A machining current supply means for supplying a current from a DC power supply to an electrode and a workpiece to generate a discharge between the electrode and the workpiece; A first inductance element provided in series with the first inductance element, a first capacitor element provided in parallel with the first inductance element, and a first capacitor element provided in parallel between the DC power supply and the electrode-workpiece. A second inductance element and a second capacitor element; a diode element provided in series between the DC power supply and the electrode-workpiece at a connection point between the second inductance element and the second capacitor element; An electric discharge machining device comprising: 2. The processing current supply means includes a resistor, a switching element, and a diode provided in series between the DC power supply and the electrode and the workpiece, and switching control for controlling an operation of the switching element. 2. The electric discharge machining apparatus according to claim 1, wherein the electric discharge machining apparatus comprises: 3. The first inductance element and the second inductance element.
3. The electric discharge machining apparatus according to claim 1, wherein the inductance value of the inductance element and the capacitance values of the first and second capacitor elements are variable.