JPH07116923A - Electric power supply for electric discharge machining - Google Patents

Abstract

PURPOSE:To control work speed by using existing DC electric power supplies effectively, and controlling electric energy to be inputted between poles. CONSTITUTION:A capacitor 8d is charged with electricity by a capacitor charging circuit 9, and charging electric charge of the capacitor 8d is accumulated in a reactor 8e as electric energy by a reactor charging circuit 10, and the electric energy accumulated in the reactor 8e is regenerated in a second DC electric power supply 6 of a DC electric power supply regenerative circuit 11, and discharge energy is supplied between a wire electrode 3 and a work 2 in which work liquid is interposed by this second DC electric power supply 6, and electric discharge machining is carried out. the electric energy to be inputted between poles is increased by using the existing first DC electric power supply 1 and second DC electric power supply effectively, so that work speed can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machine capable of effectively utilizing an existing DC power source to increase / control the electric energy supplied to the gap to improve the machining speed or control the machining speed. It concerns processing power supplies.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram of a conventional electric discharge machining power supply, and FIG. 6 is a timing waveform diagram of a conventional electric discharge machining power supply. In the figure, 1 is a first DC power supply, 2 is a workpiece, 3 is a wire electrode, 4 is a first switching element,
In this case, a power MOS-FET is used. 5
Is a current limiting resistor, 6 is a second DC power supply, and 7 is a third switching element. In this case, a power MOS-FET is used. 8 is a surge absorbing circuit, which is a diode 8a,
8b, second switching element (power MOS-FE
T) 8c, a capacitor 8d, and a reactor 8e.

Next, the circuit operation of the conventional electric discharge machining power supply will be described with reference to FIGS. The first switching element 4 between the wire electrode 3 and the workpiece 2 (hereinafter, simply referred to as "between electrodes") is turned on (timing a). Thereby, the DC voltage Vo is applied from the first DC power supply 1 (timing b), discharge is generated through the current limiting resistor 5 (timing c), and then the third switching element 7 is immediately turned on (timing b). d), a machining current (discharge current) that contributes to machining is passed between the second DC power supply 6 (timing e). Here, the voltage of the second DC power supply 6 is set to Vm.
Then, the machining current peak value Ipeak of the third switching element 7 after the predetermined on-time Ton has elapsed can be expressed by the following equation. Ipeak = (Vm / L) × Ton where L is the inductance of the electric discharge machining power supply and the feeder. Next, after the lapse of the predetermined on-time Ton, the third switching element 7 is turned off (timing f).
This series of operations is repeatedly performed, and the electric discharge machining of the workpiece 2 proceeds.

[0004]

Since the conventional electric discharge machining power supply is constructed in this way, the output voltage Vm of the second DC power supply 6 is constant, and the inductance L of the inside of the electric discharge machining power supply and the feeding feeder is constant. If the on-time Ton of the third switching element 7 is constant, the machining current peak value Ipeak is fixed and the machining speed cannot be improved. Also, the on-time Ton of the third switching element 7
However, it is impossible to supply a current higher than the current determined by the second DC power supply 6 itself.

Therefore, an object of the present invention is to provide an electric discharge machining power source which can effectively utilize an existing DC power source, control the electric energy supplied between the electrodes, and control the machining speed.

[0006]

According to a first aspect of the present invention, there is provided an electric discharge machining power source including a capacitor charging circuit having a first DC power source and a capacitor charged through a first switching element and a current limiting resistor, and the capacitor. A reactor charging circuit having a second switching element for accumulating electric energy charged in the capacitor of the charging circuit in a reactor, and a second DC power supply connected in series with a second DC power source charged by the reactor accumulating the electric energy. And a second direct current power source charged by the reactor of the direct current power source regenerative circuit, the direct current source regenerative circuit having a diode for preventing backflow is connected in series to supply a workpiece with a machining fluid and discharge energy. And a third switching element to discharge the discharge circuit.

In the electric discharge machining power source according to the second aspect, the voltage of the first DC power source can be arbitrarily set.

In the electric discharge machining power source according to the third aspect, the resistance value of the current limiting resistor can be arbitrarily set.

[0009]

In the electric discharge machining power source of claim 1, the capacitor is charged by the capacitor charging circuit, the electric charge of the capacitor is stored in the reactor by the reactor charging circuit, and the electric energy stored in the reactor is regenerated by the DC power source. Regenerated to the second DC power supply of the circuit,
Electric discharge machining is performed by this second DC power supply.

In the electric discharge machining power supply of claim 2, the voltage of the first DC power supply can be arbitrarily set, and the power supplied from the first DC power supply to the second DC power supply can be varied during the no-load time. .

In the electric discharge machining power source of the third aspect, the value of the current limiting resistance can be arbitrarily set, and the power supplied from the first DC power source to the second DC power source can be varied during the no-load time.

[0012]

【Example】

<Embodiment 1> Hereinafter, an embodiment of the electric discharge machining power source of the present invention will be described with reference to the drawings. In the figure, the same reference numerals and symbols as those of the conventional example or the other examples show the same or corresponding configuration parts as those of the conventional example or the other examples, and therefore, duplicated description will be omitted here. 1 is a circuit configuration diagram of an electric discharge machining power source according to a first embodiment of the present invention.
FIG. 6 is various timing waveform charts according to the first to third embodiments of the present invention. In FIG. 1, the difference from the electric discharge machining power supply shown in FIG. 5 of the conventional example is that the voltage polarity applied by the first DC power supply 1 between the electrodes is a negative voltage for the workpiece 2 and a positive voltage for the wire electrode 3. Has a circuit configuration that applies
The polarity is reversed from that of the conventional example. The first switching element 4, the second switching element 8c, and the third switching element 7 are on / off controlled by the control circuit 20.

Here, the first DC power supply 1, the first switching element 4, the current limiting resistor 5 connected in series to the first DC power supply 1 and the first switching element 4, and the first The capacitor 8d charged by the DC power supply 1 via the first switching element 4 and the current limiting resistor 5 constitutes the capacitor charging circuit 9 of this embodiment. Further, the capacitor 8d of the capacitor charging circuit 9, the reactor 8e connected in series to the capacitor 8d, and the second switching element 8c for accumulating the electric energy charged in the capacitor 8d in the reactor 8e,
The reactor charging circuit 10 of this embodiment is configured. The reactor 8e storing the electric energy, the second DC power source 6 charged by the reactor 8e,
The backflow prevention diode 8b connected in series with the reactor 8e and the second DC power source 6 constitutes a DC power source regeneration circuit 11 of the present embodiment. A third switching element which is connected in series to the second DC power source 6 charged by the reactor 8e of the DC power source regeneration circuit 11 and supplies discharge energy between the workpiece 2 and the wire electrode 3 in which the machining liquid is interposed. 7 constitutes the discharge circuit 12 of the present embodiment.

Next, the circuit operation of the electric discharge machining power supply according to this embodiment will be described with reference to FIGS. The first switching element 4 is turned on by the control circuit 20 between the wire electrode 3 as the processing electrode and the workpiece 2 (timing a), and the first DC power source 1 applies the DC voltage V
o is applied (timing b ′). Here, the capacitor 8d in the surge absorbing circuit 8 is charged with electric charges by the capacitor charging circuit 9 during the no-load time (the time when the discharge is not generated between the electrodes). When the voltage of the capacitor 8d reaches the constant value Vc in the steady state, the control circuit 20 turns on the second switching element 8c. As a result, the electric charge stored in the capacitor 8d is released and stored in the reactor 8e (reactor charging circuit 10). Next, when the second switching element 8c is turned off, the energy stored in the reactor 8e is regenerated by the second DC power supply 6 (DC power supply regeneration circuit 11), and the output voltage of the second DC power supply 6 is Vm.
Rise to ´. At this time, when electric discharge is generated between the electrodes (timing c ′), the third switching element 7 is immediately turned on (timing d), and the machining current that contributes to electric discharge machining from the second DC power supply 6 is generated between the electrodes. Flow (timing e
´). Here, the output voltage of the second DC power supply 6 is Vm 'because the energy stored in the reactor 8e by the DC power supply regenerating circuit 11 flows a current so as to regenerate (charge) the second DC power supply 6. (Vm <Vm '), and the machining current peak value Ipeak' after the third switching element 7 has passed the predetermined on-time Ton can be expressed by the following equation. Ipeak ′ = (Vm ′ / L) × Ton where L is the inductance of the electric discharge machining power supply and the feeder. Here, if the same on-time Ton, V
Since m <Vm ′, Ipeak <Ipeak ′, and from another viewpoint, the machining current between the wire electrode 3 and the workpiece 2 is the sum of the second DC power source 6 and the reactor 8e that has accumulated electrical energy. Therefore, a high peak machining current can be obtained. After the lapse of the predetermined on-time Ton, the third switching element 7 is turned off (timing f). This series of operations is repeatedly carried out and electric discharge machining proceeds.

Here, the first switching element 4 and the second switching element 4
The on / off timing of the switching element 8c and the third switching element 7 will be described. First, the first
The switching element 4 determines the charging voltage of the capacitor 8d of the capacitor charging circuit 9, and the charging time is mainly determined by the current limiting resistor 5 and the capacitor 8d. As the current limiting resistance 5 becomes smaller, the battery is charged faster, but at this time, the power supply capacity of the first DC power supply 1 that can withstand it is required. Normally, the on / off time of the first switching element 4 is determined by the charging time that specifies the charging voltage of the capacitor 8d of the capacitor charging circuit 9.

When the power capacity of the first DC power source 1 is large, it overlaps with the first switching element 4 and the second
There may be a timing at which the switching element 8c is turned on. Normally, in consideration of the power capacity of the first DC power supply 1, the capacitor 8d of the capacitor charging circuit 9 is charged, and when the charging is completed (when a predetermined voltage is reached).
If the first switching element 4 is turned off after that, and then the second switching element 8c is turned on, even if the power supply capacity of the first DC power supply 1 is small, the current is reduced by the current limiting resistor 5
However, once the capacitor 8d is charged, the charged electric charge can be instantly used as a charging power source for the reactor 8e having a small internal resistance of the reactor charging circuit 10. That is, usually, the first switching element 4
And the second switching element 8c turn off the first switching element 4 and then the second switching element 8c.
Is turned on, but there may be a time when both are turned on at the same time.

The timing of turning on / off the second switching element 8c and the third switching element 7 is
Since the back electromotive force of the reactor 8e having a small internal resistance of the reactor charging circuit 10 of the reactor charging circuit 10 is used as a power source, the second switching element 8c is used.
Is turned off, and immediately after that, the third switching element 7 is turned on. As a result, the second DC power source 6
Also, when the reactor 8e serves as a current source of the machining current and the counter electromotive force of the reactor 8e decreases, the diode 8b becomes reverse biased, and the reverse charging of the reactor 8e is prevented.

<Embodiment 2> FIG. 2 is a circuit diagram of an electric discharge machining power source according to a second embodiment of the present invention. In FIG. 2, reference numeral 1'denotes a first DC power supply whose output voltage can be externally set to an arbitrary voltage. Next, the circuit operation of the electric discharge machining power supply according to this embodiment will be described with reference to FIG. The control circuit 20 turns on the first switching element 4, the second switching element 8c, and the third switching element 7.
The timing of the off control is the same as that of the first embodiment shown in FIG. 4, but the difference is that the voltage of the first DC power supply 1'can be set arbitrarily. First during no-load time
The current flowing from the DC power supply 1'to the second DC power supply 6 is controlled, the output voltage Vm 'of the second DC power supply 6 is varied, and the machining current peak value is controlled. As a result, even during the same on-time Ton, Ipeak ′ changes due to the change in Vm ′, and the electric discharge machining current can be changed.

<Third Embodiment> FIG. 3 is a circuit diagram of an electric discharge machining power source according to a third embodiment of the present invention. In FIG. 3, 5'denotes a current limiting resistor composed of a variable resistor, and the resistance value can be arbitrarily set from the outside.

Next, the circuit operation of the electric discharge machining power supply according to this embodiment will be described with reference to FIG. The on / off control timing of the first switching element 4, the second switching element 8c, and the third switching element 7 by the control circuit 20 is the same as that of the first embodiment shown in FIG. 4, but different. Can control the current flowing from the first DC power supply 1 to the second DC power supply 6 during the no-load time because the resistance value of the current limiting resistor 5'can be arbitrarily set, that is, the second DC power supply 6 can be controlled. The processing voltage peak value is controlled by varying the output voltage Vm '.

As described above, the electric discharge machining power source of this embodiment includes the first DC power source 1 and the first switching element 4.
And the first DC power supply 1 and the first switching element 4
A capacitor charging circuit 9 having a current limiting resistor 5 serially connected to the capacitor, a capacitor 8d for charging the first DC power source 1 via the first switching element 4 and the current limiting resistor 5, and the capacitor charging circuit 9 Of the capacitor 8d, a reactor 8e connected in series to the capacitor 8d, and a reactor charging circuit 10 having a second switching element 8c for accumulating the electric energy charged in the capacitor 8d in the reactor 8e; The reactor 8e storing energy and the second DC power source 6 charged by the reactor 8e
A direct current power source regeneration circuit 11 having a reverse current preventing diode 8b connected in series with the reactor 8e and the second direct current power source 6, and a second direct current charged by the reactor 8e of the direct current power source regeneration circuit 11. A third switching element 7 which is connected in series to a power source 6 and supplies discharge energy between the work piece 2 and the wire electrode 3 in which a working fluid is interposed.
And a discharge circuit 12 having the above structure, which can be the embodiment of claim 1.

Therefore, the capacitor charging circuit 9 charges the capacitor 8d, and the charged electric charge of the capacitor 8d is charged by the reactor charging circuit 10 into the reactor 8e.
Electrical energy is stored in the reactor 8e, and the electrical energy stored in the reactor 8e is regenerated to the second DC power source 6 of the DC power source regeneration circuit 11. Electric discharge energy is supplied between the wire electrodes 3 to perform electric discharge machining. Therefore, it is possible to effectively utilize the existing first DC power supply 1 and second DC power supply 6, increase the electric energy input between the electrodes, and improve the processing speed. Further, the processing speed can be controlled by controlling the electric energy applied between the workpiece 2 and the wire electrode 3. Further, the electric discharge machining power source of the second embodiment can arbitrarily set the voltage of the first DC power supply 1, and this can be the embodiment of claim 2. In the case of this embodiment, it is necessary to be able to change the first DC power supply 1 ', but the electric energy input between the workpiece 2 and the wire electrode 3 can be arbitrarily set, and the machining speed You can control.

In the electric discharge machining power source of the third embodiment, the resistance value of the current limiting resistor 5 can be arbitrarily set.
This can be the embodiment of claim 3. In the case of the present embodiment, even if the outputs of the existing first DC power supply 1 and second DC power supply 6 are fixed, the output can be made variable only by changing the current limiting resistor 5 '. it can. By the way, in the above-mentioned embodiment, the wire electrode 3 is used as the electrode. However, in the case of carrying out the present invention, a die-sinking discharge electrode can be used. It can also be a device. Further, in the capacitor charging circuit 9 of the present embodiment, the workpiece 2 and the wire electrode 3 are connected between the first DC power source 1 and the current limiting resistor 5, but when the present invention is carried out, this However, the connection between the workpiece 2 and the wire electrode 3 can be separated.

[0024]

As described above, according to the electric discharge machining power source of claim 1, the capacitor is charged by the capacitor charging circuit, the charge of the capacitor is accumulated in the reactor by the reactor charging circuit, and the reactor is charged. The electric energy stored in the electric power is regenerated to the second DC power source of the DC power regeneration circuit, and the second DC power source supplies the discharge energy between the workpiece and the wire electrode in which the machining liquid is interposed to perform the electric discharge machining. It is a thing. Therefore, it is possible to effectively utilize the existing first DC power supply and second DC power supply, increase the electric energy input between the electrodes, and improve the processing speed. In addition, it is possible to control the processing speed by controlling the electric energy applied between the workpiece and the wire electrode.

In the electric discharge machining power supply of claim 2, the voltage of the first DC power supply can be set arbitrarily, and the electric energy applied between the workpiece and the wire electrode can be set arbitrarily. The processing speed can be controlled.

In the electric discharge machining power source of the third aspect, the resistance value of the current limiting resistor can be arbitrarily set, and even if the outputs of the existing first DC power source and second DC power source are fixed. The output can be made variable only by changing the current limiting resistance.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an electric discharge machining power source according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of an electric discharge machining power source according to a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of an electric discharge machining power source according to a third embodiment of the present invention.

FIG. 4 is various timing waveform diagrams according to the first to third embodiments of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional electric discharge machining power supply.

FIG. 6 is a timing waveform chart of various conventional electric discharge machining power supplies.

[Explanation of symbols]

 1 1st DC power supply 2 Work piece 3 Wire electrode 4 1st switching element 5 Current limiting resistance 6 2nd DC power supply 7 3rd switching element 8b Diode 8c 2nd switching element 8d Capacitor 8e Reactor 9 Capacitor charging Circuit 10 Reactor charging circuit 11 DC power regeneration circuit 12 Discharge circuit

Claims (3)

[Claims] 1. A first DC power supply, a first switching element connected in series with the first DC power supply, and the first DC power supply.
A capacitor charging circuit having a DC power supply and a current limiting resistor connected in series to the first switching element, and a capacitor charged by the first DC power source via the first switching element and the current limiting resistor; A reactor charging circuit having the capacitor of the capacitor charging circuit, a reactor connected in series with the capacitor, and a second switching element for storing the electric energy charged in the capacitor in the reactor, and storing the electric energy And a second DC power source charged by the reactor, a DC power source regenerative circuit in which the reactor, the second DC power source, and a diode for preventing backflow are connected in series, and the reactor of the DC power source regenerative circuit. Is connected in series with the second DC power source charged by EDM power supply, characterized by comprising a discharge circuit having a third switching element for supplying the discharge energy between the workpiece and the electrode. 2. The electric discharge machining power supply according to claim 1, wherein the voltage of the first DC power supply can be arbitrarily set. 3. The electric discharge machining power source according to claim 1, wherein the resistance value of the current limiting resistor can be arbitrarily set.