JP2764355B2 - EDM control device - Google Patents

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 control device, and more particularly to a method for detecting a voltage waveform between gaps during electric discharge machining.

[0002]

2. Description of the Related Art Conventionally, an electric discharge machine having a configuration as shown in FIG. 3 is known. That is, the electric discharge machine 1 includes a DC power supply 5 for supplying power between a workpiece 2 to be subjected to electric discharge machining and an electrode 4 opposed to the workpiece 2 with a small gap 3. A switching element 6 connected in series between the DC power supply 5 and the workpiece 2, a voltage waveform between the gaps 3 is detected by a voltage waveform detector 7, and the switching is performed by the controller 8. By adjusting the on-time Ton by the pulse-like gate signal input to the gate of the element 6, a discharge current having a desired waveform is caused to flow.

According to the electric discharge machining control device 1 having such a configuration, the voltage between the gaps 3 is changed from the point where the voltage and the current are zero by the gate signal applied to the switching element 6 as shown in FIG. Stand up to point A. At this time, the discharge is not performed between the gaps 3 and the region is an insulator, so that the current value is almost zero. At the point A, when the discharge is started between the gaps 3, the voltage becomes the discharge starting voltage Vg.
From the voltage to the discharge maintaining voltage Vo, and reaches the point B. At this time, the area between the gaps 3 is where dielectric breakdown grows.
Thereafter, from point B to point C, the discharge is maintained between the gaps 3 and is in a plasma state. Here, the voltage waveform detection device 7 generally detects the voltage waveform by separating the voltage between the gaps 3 in order to eliminate the influence of the voltage waveform.

[0004]

However, according to such a method of detecting the voltage waveform between the gaps 3, the signal transmission delays due to the potential separation, and the voltage waveform detection and A serious problem arises with regard to the control of the electric discharge machining. In recent years, a photocoupler can be used for potential separation, and the above-described delay time related to signal transmission has been shortened. Then, there is a problem that accurate signal transmission cannot be performed.

In view of the above, the present invention provides an electric discharge machining control device capable of detecting a voltage waveform between gaps at the time of electric discharge machining with substantially no delay time in a state where potentials are separated. The purpose is.

[0006]

According to the present invention, there is provided, in accordance with the present invention, a dc power source for supplying power between an electrode facing a workpiece to be subjected to electrical discharge machining with a small gap. A power supply, and a switching element connected in series between the DC power supply and the workpiece or the electrode, and detects a voltage waveform between the gaps during electric discharge machining, based on the voltage waveform. In the electric discharge machining apparatus configured to perform the electric discharge machining by adjusting the on-time of the switching element with a gate signal having a predetermined pulse width, a means for detecting a voltage waveform at the time of the electric discharge machining includes a voltage between the gap. It is configured to detect the waveform by separating the potential through a pulse transformer, and the primary side of the pulse transformer connects the second switching element. Is applied a voltage waveform between the gap and, this second switching element is configured to be on-controlled by the gate signal when the electric discharge machining.

[0007]

According to the above construction, the voltage waveform between the gaps to be detected is applied to the primary side of the pulse transformer in synchronization with the pulsed gate signal at the time of electric discharge machining, so that there is substantially no delay time. Since a voltage waveform is generated on the secondary side of the pulse transformer in a state where the potential is separated, an accurate voltage waveform can be detected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 shows the configuration of an electric discharge machining control device according to an embodiment of the present invention. This control device 1
Numeral 0 denotes an input terminal 11 to which a voltage waveform generated between the workpiece 2 and the gap 3 between the electrodes 4 of the electric discharge machine 1 shown in FIG. A pulse transformer 14 having a primary terminal 14a connected via a smoothing circuit 13, and a rectifying voltage dividing circuit 15 is connected to a secondary terminal 14b of the pulse transformer 14.
The output terminal 16 connected via the control device 8 of FIG.
A control input terminal 17 to which a gate signal is input from the control element 17, a secondary terminal 21 a connected to the control input terminal 17 via a switching element, in this case, FETs 18, 19 and a capacitor 20, and the switching element 12. And a second pulse transformer 21 having a primary terminal 21b connected to the gate of the second pulse transformer 21.

According to the control device 10 configured as described above, the voltage waveform during electric discharge machining is input from the input terminal 11 to the primary side of the pulse transformer 14 via the switching element 12 and the rectifying / smoothing circuit 13. Pulse transformer 1
4 through a rectifying / smoothing circuit 15 to an output terminal 16
Is output from

Here, when the gate signal input to the control input terminal 17 changes from L level to H level, the FET 18
Is turned on, and the FET 19 is turned off. FET1
8, the voltage is applied to the secondary terminal 21a of the pulse transformer 21 via the capacitor 20, and
Since the signal is input to the gate of the switching element 12 via the pulse transformer 21, the switching element 12 is turned on. Therefore, the primary terminal 1 of the pulse transformer 14
The voltage waveform between the gaps is input to the input terminal 4a from the input terminal 11, and the pulse transformer 14 generates an analog voltage waveform on the secondary side. After being rectified by
A voltage waveform having a desired level is formed by the voltage dividing resistors 15b, 15c, and 15d, and output from the output terminal 16. The resistor 15e and the capacitor 15f of the rectifying voltage dividing circuit 15 are
This is for phase correction.

When the gate signal input to the control input terminal 17 changes from H level to L level, the FET 18 turns off and the FET 19 turns on. As a result, the polarity of the secondary side of the pulse transformer 21 is reversed, so that a negative voltage is applied to the gate of the switching element 12, so that the switching element 12 is turned off and the pulse transformer 14 is turned off. No voltage can be applied to the primary terminal 14a. At this time, the pulse transformer 14
Is stored in the capacitor 13a of the rectifying / smoothing circuit 13, and is consumed as heat energy by the resistor 13b.

Thus, the voltage waveform between the gaps input to the input terminal 11 can be transmitted to the output terminal 16 only when the gate signal for controlling the electric discharge machining is at the H level. The propagation delay is substantially negligible, for example a few picoseconds.

[0013]

As described above, according to the present invention, the voltage waveform between the gaps to be detected is applied to the primary side of the pulse transformer in synchronization with the pulsed gate signal at the time of electric discharge machining. Since the voltage waveform is generated in a state where the potential is separated on the secondary side of the pulse transformer without substantially any delay time, accurate detection of the voltage waveform is performed. Thus, according to the present invention, there is provided an extremely excellent electric discharge machining control device capable of detecting a voltage waveform between gaps at the time of electric discharge machining with a potential separation substantially without a delay time.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of an electric discharge machining control device according to the present invention.

FIG. 2 is a time chart showing an input waveform, a gate signal, and an output waveform in the embodiment of FIG.

FIG. 3 is a circuit diagram showing an example of a conventional electric discharge machining control device.

FIG. 4 is a graph showing changes in voltage and current during electric discharge machining.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 electric discharge machining control device 11 input terminal 12 switching element 13 rectifying and smoothing circuit 14 pulse transformer 15 rectifying voltage dividing circuit 16 output terminal 17 control input terminal 18 FET 19 FET 20 capacitor 21 pulse transformer

Claims (1)

(57) [Claims] 1. A DC power supply for supplying electric power between an electrode facing a workpiece to be subjected to electric discharge machining with a small gap, and a series between the DC power supply and the workpiece or the electrode. And a switching element connected to the sensor, detects a voltage waveform between the gaps during electric discharge machining, and determines an on-time of the switching element with a gate signal having a predetermined pulse width based on the voltage waveform. In the electric discharge machine, wherein the electric discharge machining is performed by adjusting, the means for detecting a voltage waveform at the time of electric discharge machining detects the voltage waveform between the gaps by separating the voltage waveform through a pulse transformer. And the primary side of the pulse transformer is applied with a voltage waveform between the gaps via a second switching element, and the second switching Child, characterized in that it is on-controlled by the gate signal when the electrical discharge machining, electric discharge machining controller.