JPH0911042A - Electric discharge machining device - Google Patents

Abstract

PURPOSE: To dispense with necessity for changing a reference voltage of a servo reference circuit even in a change of a power source voltage so as to face facilitate operation of the servo reference circuit, to prevent damage on a machining face in a change of the power source voltage, to easily set an optimum reference voltage, and to increase machining speed. CONSTITUTION: In an electric discharge machining device, voltage is impressed to a clearance between a workpiece 2 and an electrode 1 arranged opposedly to the workpiece 2 so as to carry out electric discharge machining in the workpiece 2, and on the basis of a mean voltage impressed to the clearance during electric discharge machining, a length of the clearance is controlled by moving either/both of the workpiece 2 and the electrode 1. In the electric discharge machining device, the mean voltage between the power source voltage on the power source 9 side to be impressed to the clearance and a voltage impressed to the clearance is detected. A ratio between the power source voltage and the mean voltage is found by means of an analog divider 761, and on the basis of a difference between the output from the analog divider 761 and the predetermined reference voltage, a length of the clearance is controlled.

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 such as a die-sinking electric discharge machine and a wire electric discharge machine.
The present invention relates to an electric discharge machine that simplifies control of a gap length for electric discharge machining and its setting operation.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram of a conventional die-sinking electric discharge machining apparatus for fine machining such as fine hole machining. In the figure, 1
Is an electrode formed in a predetermined processing shape, 2 is a workpiece to be transferred and processed by the electrode 1, 3 is a quill attached to a mechanical head of a mechanical system (not shown), 4 is a quill 3 driven by a ball screw or the like The servo motor 5 moves the position of the electrode 1, the encoder 5 detects the position of the electrode 1 from the rotation of the servo motor 4, and the general-purpose servo amplifier 6 drives the servo motor 4. 8 is a capacitor, 9 is a power supply,
Reference numeral 10 is a current limiting resistance, which constitutes a power supply circuit for processing, and the output voltage thereof is applied to the electrode 1 and the workpiece 2. This type of power supply circuit for processing is generally called a capacitor discharge circuit.

Capacitor discharge circuits are often used for fine and fine surface roughness machining. Specifically, the capacitor 8 is composed of a plurality of capacitors, which are connected in parallel via a relay, a switch, etc., and a circuit is constructed so that a required number of capacitors are connected in parallel by each relay or switch. Is common. Also,
The power supply 9 changes the output voltage according to the processing content (processing conditions) and adjusts to an optimum voltage value. Reference numeral 7 is a servo reference circuit that issues a command to a general-purpose servo amplifier 6 that controls a gap length that is a discharge gap between the electrode 1 and the workpiece 2.

The servo reference circuit 7 is constructed as follows. Reference numerals 701 and 702 denote voltage dividing resistors for detecting the voltage division of the gap between the electrode 1 and the workpiece 2. 708
Is a constant voltage supplied from a constant voltage source (not shown) of the control system,
The voltage is divided by the voltage dividing resistor 703 and the voltage dividing resistor 707, and the divided voltage is applied to the operational amplifier 705 as a reference voltage. The operational amplifier 705 amplifies the difference between the divided voltage of the gap and the reference voltage and outputs it as a speed command of the general-purpose servo amplifier 6. Reference numeral 704 is an input resistance of each + input terminal, − input terminal, 706 is a feedback resistance, and determines the gain of the operational amplifier 705. The voltage dividing resistor 707 composed of a potentiometer has a function of changing the servo reference voltage.

FIG. 6 shows an example of a power source 9 in the circuit configuration diagram of a conventional die-sinking electric discharge machining apparatus for fine machining such as fine hole machining. In FIG. 6, reference numeral 901 denotes a power source that outputs a predetermined voltage, and 90
Reference numeral 2 is a transistor for performing a switching operation, 903 is a reactor for suppressing high frequency components, 904 is an electrolytic capacitor, and 905 is a flywheel diode. 9
Reference numerals 06 and 907 denote voltage dividing resistors composed of resistors connected in series and divide the voltage across the electrolytic capacitor 904. 9
Reference numeral 17 is a constant voltage supplied from the control system. 908 and 9
Reference numeral 09 denotes a voltage dividing resistor composed of resistors connected in series, which divides the constant voltage 917 of the control system to obtain a predetermined reference voltage. 9
Reference numeral 11 is an operational amplifier including an operational amplifier, 918 is an input resistance for inputting the voltage detected by the voltage dividing resistors 906 and 907 and an input resistance for inputting the voltage detected by the voltage dividing resistors 908, 909, and 910 is an operational amplifier 911. Of the input resistance 918 and the feedback resistance 910 determines the gain of the operational amplifier 911. Reference numeral 912 is a comparator, and 913 is an oscillator for generating a sawtooth wave, and usually a repetitive pulse frequency of 10 to 500 kHz is used. Reference numeral 914 is a photocoupler for providing insulation between electric circuits, 915 is a current limiting resistor for limiting a current flowing through the photocoupler 915, and 916 is a photocoupler 91.
5 is a gate amplifier that controls switching of the transistor 902 with the signal of FIG.

Next, the circuit operation of the conventional die-sinking electric discharge machine shown in FIGS. 5 and 6 will be described. First, the power supply 9 will be described. When the transistor 902 is turned on, it is output from the power source 901 through the transistor 902 and the reactor 903 to both terminals of the electrolytic capacitor 904 to the load side. At this time, the electrolytic capacitor 904 is charged at the same time as the reactor 903 is energized. When the transistor 902 is turned off, the energy that the reactor 903 has becomes a current, and the electrolytic capacitor 904 and the diode 9
Circulate through 05. When the transistor 902 continues to be in the off state, the load connected to the electrolytic capacitor 904 causes the voltage to sequentially decrease.

The voltage across the electrolytic capacitor 904 is detected by the voltage dividing resistors 906 and 907, and the operational amplifier 91 is detected.
At 1, the difference from the reference voltage input by the voltage dividing resistors 908 and 909 is amplified. At this time, the electrolytic capacitor 9
When the voltage of 04 is low, the output of the operational amplifier 911 becomes low. The sawtooth wave from the oscillator 913 is input to one of the comparators 912, and the operational amplifier 911 is input to the other, and both inputs are compared. When the output of the operational amplifier 911 is low, the comparator 912 outputs a low level, the photodiode of the photocoupler 914 emits light, and the gate amplifier 916 turns on the transistor 902. When the voltage of the electrolytic capacitor 904 becomes higher, the output of the operational amplifier 911 becomes higher, and in the comparator 912, the oscillator 913
The comparator 912 outputs a low level only when the output of the operational amplifier 911 is low as compared with the sawtooth wave from, and the photodiode of the photocoupler 914 illuminates, turning on the transistor 902 in the gate amplifier. When the voltage of the electrolytic capacitor 904 becomes higher, the output of the operational amplifier 911 becomes higher, and the comparator 912 compares the output with the sawtooth wave from the oscillator 913 and
, The comparator 912 outputs a high level, the photodiode 914 of the photocoupler 914 is turned off, and the gate amplifier 916 turns off the transistor 902.

In this manner, the voltage across the electrolytic capacitor 904 is maintained at a constant voltage by the transistor 902 based on the voltage across the electrolytic capacitor 904.
Is PWM controlled. At this time, the electrolytic capacitor 904
The voltage across both ends of the voltage divider resistor 9 consisting of a potentiometer.
The resistance value of 09 can be arbitrarily set, and can be set to a voltage value convenient for processing.

Next, the servo reference circuit 7 will be described. The voltage applied between the electrode 1 and the workpiece 2, that is, the gap voltage, is divided by the voltage dividing resistors 701 and 702,
It is input to the operational amplifier 705 via the input resistor 704. On the other hand, the voltage of the constant voltage 708 of the control system is also the voltage dividing resistor 70.
The voltage is divided by 3, 707 and input to the operational amplifier 705 via the input resistor 704.
The difference is amplified at. The amplification factor is determined by the input resistor 704 and the feedback resistor 706. The output of the operational amplifier 705 is output to the general-purpose servo amplifier 6, and the positive / negative of the output causes the servomotor 4 to rotate normally or reversely. That is, the servo reference circuit 7 detects the average voltage during processing, and based on this voltage, feed control of the electrode 1 or the workpiece 2 is performed so that the relative distance between the electrode 1 and the workpiece 2 is maintained constant. I do. That is, when the detected average voltage is equal to or higher than the predetermined value, it means that the number of discharges per unit time is small. Therefore, the feeding speed of the electrode 1 or the workpiece 2 is increased, and the average voltage is equal to or lower than the predetermined value. In this case, since it means that the number of discharges per unit time is large, the feed of the electrode 1 or the workpiece 2 is set back.

The electric charge charged in the capacitor 8 is stored in the electrode 1
Flows due to the dielectric breakdown in the gap between the workpiece and the workpiece 2, whereby the electric discharge machining is advanced. The capacity of the capacitor 8 determines each discharge energy. Increasing the capacity increases the discharge energy and increases the processing speed, but on the other hand, the surface roughness becomes rough. Therefore, the capacitance of the capacitor 8 is selected and determined according to the desired surface roughness. The power source 9 also determines the discharge energy for each shot. If the voltage of the power source 9 is increased, the charging speed is increased, the discharge energy is increased, and the processing speed is increased. But,
On the other hand, the surface roughness becomes rough. Further, the voltage value of the power source 9 also affects the gap length. The higher the voltage value, the farther the discharge flies, so the gap length becomes wider, which makes it easier to remove the machining powder generated and stabilizes the machining. However, when it is desired to process a thin hole, the gap length cannot be widened when the thickness of the electrode 1 is limited.
Further, if the gap length is wide, the transferability of the shape of the electrode 1 to the work piece 2 is deteriorated. That is, the voltage value of the power source 9 needs to be set according to the purpose of processing. Therefore, adjustment of the average voltage of the gap is important. When the average voltage is set high, the no-load time becomes long, the discharge frequency becomes low, and the machining speed also decreases. On the other hand, the current limiting resistor 10 determines the charging current to the capacitor 8. If the resistance value is reduced, the charging of the capacitor 8 becomes faster, so that the repeated discharge frequency becomes higher, and as a result, the processing speed becomes faster. On the other hand, abnormal discharge is likely to occur and the processing tends to be unstable. Therefore, it is necessary to appropriately select the value of the current limiting resistor 10 with respect to the capacity of the capacitor 8.

Here, if the average voltage is set higher than the voltage of the power source 9, no load time is continuous and no electric discharge machining is performed. If you set the average voltage low,
The discharge frequency becomes higher and the machining speed improves, but on the other hand,
Electric discharge machining becomes extremely unstable due to a short circuit or abnormal discharge. Moreover, the machined surface may be rough. Therefore, when the voltage setting of the power supply 9 is changed, it is necessary to change the reference voltage by the voltage dividing resistor 707 of the servo reference circuit 7.

As described above, in the electric discharge machining, it is necessary to control the gap length between the electrode 1 and the workpiece 2, but it is impossible to measure the actual gap length. Alternatively, whether the gap is too narrow is determined by measuring the average voltage applied to the gap between the electrode 1 and the workpiece 2, and the gap length is controlled to an optimum length. For example, if the gap length is too wide, the occurrence of discharge is reduced, so that the no-load time becomes longer and the average voltage becomes higher. On the contrary, if the gap length is too narrow, the occurrence of discharge increases, so that the no-load time becomes short, or a short circuit occurs and the average voltage becomes low. Therefore, by moving the electrode 1 or the workpiece 2 or both so that the average voltage of the gap becomes a predetermined value, an appropriate gap length is maintained and smooth electric discharge machining is continued.

[0013]

As described above, the conventional electric discharge machining apparatus has the capacity of the capacitor 8 depending on the machining content.
The reference voltage is set by the value of the current limiting resistor 10, the voltage value of the power supply 9, and the voltage dividing resistor 707 of the servo reference circuit 7. At this time, first, according to the target surface roughness, the capacitor 8
Of the current limiting resistor 10 with respect to the capacitance of the capacitor 8 is determined. Next, the voltage value of the power supply 9 is determined, and then the reference voltage is determined by the voltage dividing resistor 707 of the servo reference circuit 7 according to the voltage value of the power supply 9. During electric discharge machining, the voltage value of the power supply 9 is adjusted according to the electric discharge state. When adjusting the power supply 9, the reference voltage of the servo reference circuit 7 must be changed at the same time. If the reference voltage is not changed, abnormal discharge will occur and machining will be unstable. Furthermore, such abnormal discharge is easy to continue,
At the same time, an excessive current may be concentrated on one location and the surface of the workpiece 2 may be damaged.

In the capacitor discharge circuit, if the conditions of the voltage of the capacitor 8, the current limiting resistor 10 and the power source 9 are constant, the machining speed is proportional to the discharge energy discharged within a unit time, that is, the discharge power W. Then, it can be assumed that the average voltage that maximizes the discharge power W is obtained. If the capacitor voltage at the start of discharge is Vo, then Vo = E (1-ε- ^αt ). However, α = 1 / CR. Also, E: voltage value of the power supply 9, C: capacitance of the capacitor 8, R: value of the current limiting resistor 10, t: charging time
It is. Since the discharge time of the electric discharge machining is usually several% or less of the charge time, the discharge repeating pulse period may be considered as t. Energy Wo released by one discharge is Wo = C (Vo ² −V ² ) / 2, where V is a residual voltage. Normally, the residual voltage V is 30% or less of the capacitor voltage Vo, so it can be ignored in the calculation of the energy Wo released by one discharge. Therefore, the discharge power W discharged per unit time is W = C · Vo ² / 2t = C · E ² · (1-ε- ^αt ) ²
/ 2t.

Further, in order to obtain the maximum value of the discharge power W discharged in a unit time, when dW / dt = 0 is rearranged, ε ^ατ = 2ατ + 1 where τ; is t when W becomes maximum. If this is solved graphically, ατ≈1.3. Here, if the average voltage of the capacitor voltage Vo is Vm

(Equation 1) Becomes Further, when the discharge power W emitted per unit time is the maximum, Vm = 0.445E. That is, when the average voltage Vm applied to the gap between the electrode 1 and the workpiece 2 is 44.5% of the voltage of the power source 9 as a guide, the electrode 1 is automatically fed to obtain the maximum processing speed. . Therefore, when the voltage E of the power source 9 is changed, the servo reference voltage, that is, the reference voltage must be changed by the voltage dividing resistor 707 of the servo reference circuit 7.

Therefore, the present invention has been made to solve such a problem, and it is not necessary to change the reference voltage of the servo reference circuit even when the power supply voltage is changed, and the operation is simplified. In addition, it is an object of the present invention to provide an electric discharge machining apparatus capable of avoiding damage to the machining surface when changing the power supply voltage, easily setting an optimum reference voltage, and improving the machining speed.

[0017]

According to a first aspect of the present invention, there is provided an electric discharge machining apparatus in which a voltage is applied to a gap between a work piece and an electrode arranged to face the work piece. And an electric discharge machining apparatus for controlling the gap length by moving one or more of the workpiece and the electrode based on an average voltage applied to the gap during the electric discharge machining,
The average voltage of the power supply voltage applied to the gap and the voltage applied to the gap is detected, and the ratio of the power supply voltage and the average voltage is obtained by a divider, and the output of the divider and a predetermined reference voltage. The gap length is controlled on the basis of the difference.

According to a second aspect of the present invention, there is provided an electric discharge machine, wherein a voltage is applied to a gap between a work piece and an electrode arranged to face the work piece to perform the electric discharge machining on the work piece. In an electric discharge machine that controls the gap length by moving one or more of the workpiece and the electrode based on an average voltage applied to the gap during electric discharge machining, a power supply voltage on the power supply side applied to the gap. And an average voltage of the voltages applied to the gap are detected, the ratio of the power supply voltage to the average voltage is obtained by a divider, and the difference between the output of the divider and a predetermined reference voltage is converted into a digital signal and the NC device is obtained. And the gap length is controlled by the NC device based on the difference between the output of the divider and a predetermined reference voltage.

According to a third aspect of the electric discharge machining apparatus, a voltage is applied to a gap between a work piece and an electrode arranged so as to face the work piece, and the electric discharge machining is performed on the work piece. In an electric discharge machine that controls the gap length by moving one or more of the workpiece and the electrode based on an average voltage applied to the gap during electric discharge machining, a power supply voltage on the power supply side applied to the gap. And the average voltage of the voltages applied to the gap is detected, the ratio of the power supply voltage to the average voltage is obtained by a divider, and the output of the divider is converted to digital to obtain N.
Input to a C device, the NC device obtains the difference between the output of the divider and a predetermined reference voltage, and controls the gap length based on the difference between the output of the divider and the predetermined reference voltage. Is.

[0020]

According to the present invention, the average voltage of the power supply voltage applied to the gap between the work piece and the electrode arranged facing the work piece and the average voltage of the voltage applied to the gap is The gap length is detected and the gap length is controlled based on the difference between the ratio of the power supply voltage and the average voltage and a predetermined reference voltage, and the gap length can be controlled based on the ratio of the average voltage of the gap to the power supply voltage.

According to another aspect of the present invention, the average voltage of the power supply voltage applied to the gap between the work piece and the electrode facing the work piece and the voltage applied to the gap is defined as: The ratio of the power supply voltage to the average voltage is detected by a divider, the difference between the output of the divider and a predetermined reference voltage is converted into digital and input to an NC device, and the NC device outputs the difference of the divider. Since the gap length is controlled based on the difference between the output and the predetermined reference voltage, the gap length can be controlled based on the ratio of the power supply voltage and the average voltage, and the NC device can control the multiaxial gap. it can.

According to a third aspect of the present invention, the average voltage of the power supply voltage applied to the gap between the workpiece and the electrode arranged facing the workpiece and the voltage applied to the gap is The ratio of the power supply voltage to the average voltage is detected by a divider, the output of the divider is converted to digital, and NC
The NC device calculates the difference between the output of the divider and a predetermined reference voltage, and controls the gap length based on the difference between the output of the divider and the predetermined reference voltage. Therefore, the gap length can be controlled based on the ratio of the power supply voltage and the average voltage, and the NC device can perform multiaxial gap control, and the reference voltage can be easily changed.

[0023]

EXAMPLE An example of a die-sinking electric discharge machine as an electric discharge machine of the present invention will be described below. Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a circuit configuration diagram showing a die-sinking electric discharge machine according to a first embodiment of the present invention. In FIG. 1, an electrode 1, a workpiece 2, a quill 3, a servo motor 4, an encoder 5, a general-purpose servo amplifier 6, a power supply 9, a current limiting resistor 10 and a capacitor 8 are different from the components described in the conventional example. Therefore, redundant description will be omitted here. FIG.
In the above, 762 is a voltage detection circuit that detects the voltage of the power supply 9, that is, the power supply voltage, and 763 is an average voltage detection circuit that detects the average voltage applied to the gap formed between the electrode 1 and the workpiece 2.

Further, the voltage detection circuit 762 and the average voltage detection circuit 763 will be described in detail. 751 and 7
Reference numeral 52 is a voltage dividing resistor composed of resistors connected in series for detecting the voltage of the power source 9. Reference numeral 755 is an operational amplifier including an operational amplifier, and 753 is an input resistance of the operational amplifier 755. Similarly, 756 and 757 are voltage dividing resistors for detecting the average voltage applied to the gap formed between the electrode 1 and the workpiece 2. Reference numeral 760 is an operational amplifier including an operational amplifier, 7
Reference numeral 58 is an input resistance of the operational amplifier 760. Also, 76
Reference numeral 1 is a commercially available divider in the form of an IC circuit. In this embodiment, A is sold by Analog Devices.
D535 (model name) is used. The output of the operational amplifier 755 is connected to the X1 terminal of the divider 761 and the output of the operational amplifier 760 is connected to the Z2 terminal of the divider 761. The X2 terminal and the Z1 terminal of the divider 761 are connected to zero volt (ground). The Y1 terminal of the divider 761 is connected to zero volt, and the Y2 terminal is connected to the OUT terminal. The SF terminal of the divider 761 is not connected. Divider 761 +
The Vs terminal and the -Vs terminal are respectively connected to the voltage of the control system. Further, 703 and 707 form a servo reference voltage by dividing the constant voltage 708 of the control system. Reference numeral 705 is an operational amplifier, 704 is an input resistance, and 706 is a feedback resistance.

Next, the circuit operation of the die sinking electric discharge machine of this embodiment will be described. First, if the full-scale voltage Vover is used, the output voltage Vout according to the following equation is output from the OUT terminal from the divider 761. Vout = Vover. (Z2-Z1) / (X1-X2) + Y
1 In the above equation, assuming that Z1, X2, and Y1 are connected to zero volt, the following equation can be simplified. Vout = Vover · Z2 / X1 Here, the output from the OUT terminal of the divider 761 shown in the above equation indicates the ratio of the average voltage of the gap to the voltage value of the power supply voltage of the power supply 9. The output of the divider 761 is input to the operational amplifier 705, and the reference voltage given by the voltage dividing resistor 707 of the servo reference circuit 7, that is, the difference from the servo reference voltage is amplified. The output of the operational amplifier 705 is input to the general-purpose servo amplifier 6. If the servo reference voltage is set to, for example, 4.45 volts, the gap length is controlled so that the average voltage of the gap becomes 44.5% of the voltage value of the power supply 9.

Therefore, even if the voltage value of the power source 9 is changed during the electric discharge machining, the average voltage of the gap which always provides the optimum efficiency can be maintained. Therefore, if the setting of only the average voltage is adjusted to a low value, the discharge frequency becomes higher, the machining speed improves, and at the same time, electrical discharge machining becomes extremely unstable due to short circuit or abnormal discharge. However, in the present embodiment, even if the voltage value of the power supply 9 is changed during processing, abnormal discharge does not occur, and in addition, an excessive current is concentrated in one place. Damage to the surface of the workpiece due to the supply is also eliminated. Further, the present invention can be implemented in the same manner even in the transistor pulse system used for the low wear processing of the electrode 1. Further, the present invention can be implemented in exactly the same manner even in the conventional method of controlling the gap length based on the average voltage of the gap.

As described above, in the electric discharge machining apparatus of this embodiment, a voltage is applied to the gap between the workpiece 2 and the electrode 1 arranged so as to face the workpiece 2, and the workpiece 2 is cut. In an electric discharge machining apparatus for controlling the gap length by moving one or both of the workpiece 2 and the electrode 1 based on the average voltage applied to the gap during the electric discharge machining. The average voltage of the power supply voltage on the side of the power supply 9 to be applied and the voltage applied to the gap is detected, the ratio of the power supply voltage to the average voltage is obtained by the divider 761, and the output of the divider 761 and the predetermined reference voltage are calculated. The gap length is controlled based on the difference, which can be an embodiment corresponding to the claims.

The average voltage of the power supply voltage applied to the gap between the workpiece 2 and the electrode 1 arranged facing the workpiece 2 on the power source 9 side and the voltage applied to the gap is detected, The gap length is controlled based on the difference between the ratio of the power supply voltage and the average voltage and a predetermined reference voltage. Therefore, even if the power supply voltage is changed during electric discharge machining by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage,
It is possible to maintain stable electric discharge machining without the electric discharge machining becoming unstable or abnormal machining. Further, the most efficient processing condition can be selected for the power supply voltage.

Example 2. FIG. 2 is a circuit configuration diagram showing a die-sinking electric discharge machining apparatus of a second embodiment of the present invention, which is an example of moving multiple axes by an NC apparatus. In the drawings, the same reference numerals and symbols as those of the first embodiment indicate the same or corresponding components as those of the first embodiment, and therefore, redundant description will be omitted here, and only the differences will be described. And In this embodiment, the output of the divider 761 is the servo reference circuit 7
Input to the A / D converter 1 and the output of the servo reference circuit 7
2 and is decomposed into a digital signal with an appropriate resolution. The output of the A / D converter 12 is read into the NC device 11, and the general-purpose servo amplifier 6 drives the electrode 1. The overall operation is similar to that of the first embodiment, and in particular, in this embodiment, the NC device 11 enables multi-axis control.

In the case of this kind of embodiment, when the average voltage applied to the gap formed between the electrode 1 and the workpiece 2 is read by the A / D converter, the power supply voltage value of the power supply 9 is changed to A / D. Compared with the case of reading with a converter, in the case of this embodiment, A / D
There is an advantage that the resolution of the converter 12 is low. That is,
When the average voltage is read by the A / D converter and when the power supply voltage value of the power supply 9 is read by the A / D converter, it is necessary to assume that the power supply voltage is from high to low, and when it is low. When the resolution is adjusted to, the required number of bits increases when the resolution is high. On the contrary, if the resolution is adjusted when it is high, it becomes insensitive when it is low. However, in this embodiment, since the power supply voltage of the power supply 9 is not affected, the resolution is inevitably low. Therefore, the average voltage is A /
When reading with the D converter and the power supply voltage value of the power supply 9 is A / D
Compared with the case of reading with a converter, in the present embodiment, A /
Not only is the D converter 12 inexpensive, but the number of input ports of the NC device 11 is small, and the NC device 11 can be constructed at a low cost. That is, as compared with a conventional circuit in which digital processing is changed and the average voltage is read by an A / D converter, the resolution is low and the cost is low.

As described above, in the electric discharge machining apparatus of this embodiment, a voltage is applied to the gap between the workpiece 2 and the electrode 1 arranged so as to face the workpiece 2, and the workpiece 2 is cut. In an electric discharge machining apparatus for controlling the gap length by moving one or both of the workpiece 2 and the electrode 1 based on the average voltage applied to the gap during the electric discharge machining. The average voltage of the power source voltage on the side of the power source 9 to be applied and the voltage applied to the gap is detected, the ratio of the power source voltage to the average voltage is obtained by a divider 761, and the output of the divider 761 and a predetermined reference voltage. Is converted into a digital signal by the A / D converter 12 and is input to the NC device 11.
1 controls the gap length based on the difference between the output of the divider 761 and a predetermined reference voltage.

The average voltage of the power supply voltage on the side of the power source 9 applied to the gap between the workpiece 2 and the electrode 1 arranged facing the workpiece 2 and the voltage applied to the gap is detected. ,
The ratio of the power supply voltage to the average voltage is obtained by a divider 761, and the difference between the output of the divider 761 and a predetermined reference voltage is converted into digital and input to the NC device 11, and the divider is used by the NC device 11. Since the gap length is controlled based on the difference between the output of 761 and a predetermined reference voltage, the gap length can be controlled based on the ratio between the power supply voltage and the average voltage. The gap can be controlled. Therefore, by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage, even if the power supply voltage is changed during electric discharge machining, the electric discharge machining does not become unstable or abnormal machining occurs. In addition, stable electrical discharge machining can be maintained. Further, the most efficient processing condition can be selected for the power supply voltage. Further, the NC device 11 enables multi-axis control. Since the resolution is lower than that of reading the conventional average voltage with an A / D converter, the cost is low.

Embodiment 3 FIG. FIG. 3 is a circuit configuration diagram showing a die-sinking electric discharge machining apparatus of a third embodiment of the present invention, which is an example of moving multiple axes by an NC apparatus. FIG. 4 is a flowchart for performing servo control of the NC device of the die-sinking electric discharge machine according to the third embodiment of the present invention. In the drawings, the same reference numerals and symbols as those in each of the above-mentioned embodiments indicate the same or corresponding components as those of the above-mentioned respective embodiments, and therefore, redundant description will be omitted here, and only different points will be described. And In the present embodiment, the output of the divider 761 is input to the A / D converter 12 and decomposed into a digital value with an appropriate resolution. The output of the A / D converter 12 is read into the NC device 11, and inside the NC device 11, the reference voltage setting device 13 corresponding to the reference voltage set by the voltage dividing resistor 707 of the servo reference circuit 7 of the above embodiment is used. The electrode 1 is driven by the general-purpose servo amplifier 6 based on the difference from the set reference voltage. The overall operation is the same as the above-mentioned embodiment. In particular, in this embodiment, the NC device 11 enables multi-axis control.

In the NC unit 11, the servo control program is called while the main program for predetermined numerical control is being executed. First, in step S1, it is determined whether or not the output of the A / D converter 12 is larger than the output set in the reference voltage setting device 13. If it is larger, in step S2 the servo motor 4 via the general-purpose servo amplifier 6 is selected. Is used as the normal output, and the relative distance between the electrode 1 and the workpiece 2 is shortened. Step S3
Determines whether the output of the A / D converter 12 is smaller than the output set in the reference voltage setting unit 13, and if it is smaller, the servo motor 4 is sent via the general-purpose servo amplifier 6 in step S4.
Is set as the reverse output, and the relative distance between the electrode 1 and the workpiece 2 is lengthened. When the gap length is appropriate, this routine is exited.

In the case of this kind of embodiment, when the average voltage applied to the gap formed between the electrode 1 and the workpiece 2 is read by the A / D converter, the power supply voltage value of the power supply 9 is changed to A / D. Compared with the case of reading with a converter, in the case of this embodiment, A / D
There is an advantage that the resolution of the converter 12 is low. Also,
In this embodiment, since the power supply voltage of the power supply 9 is not affected, the resolution is inevitably low. Therefore, comparing the case where the average voltage is read by the A / D converter and the case where the power source voltage value of the power source 9 is read by the A / D converter,
In the present embodiment, not only the A / D converter 12 becomes inexpensive, but also the number of input ports of the NC device 11 is small, and the NC device 11 can be inexpensively constructed. That is, as compared with a conventional circuit in which digital processing is changed and the average voltage is read by an A / D converter, the resolution is low and the cost is low. Further, the reference voltage can be set by the NC device 11
The reproducibility is improved because it is controlled by. Of course, even if the voltage of the power source 9 is changed during processing, it is not necessary to change the reference voltage.

As described above, in the electric discharge machining apparatus of this embodiment, a voltage is applied to the gap between the workpiece 2 and the electrode 1 arranged so as to face the workpiece 2, and the workpiece 2 is cut. In an electric discharge machining apparatus for controlling the gap length by moving one or both of the workpiece 2 and the electrode 1 based on the average voltage applied to the gap during the electric discharge machining. The average voltage of the power source voltage on the side of the power source 9 to be applied and the voltage applied to the gap is detected, the ratio of the power source voltage to the average voltage is obtained by the divider 761, and the output of the divider 761 is converted into a D / A converter. Converted to digital at 12 and NC device 1
1, the NC device 11 calculates the difference between the output of the divider 761 and a predetermined reference voltage, and controls the gap length based on the difference between the output of the divider 761 and the predetermined reference voltage. is there.

The average voltage of the power supply voltage applied to the gap between the workpiece 2 and the electrode 1 arranged facing the workpiece 2 on the power source 9 side and the voltage applied to the gap is detected, The ratio of the power supply voltage to the average voltage is obtained by the divider 761, and the output of the divider 761 is converted into digital data to obtain the NC device 11.
Is input to the NC device 11, the difference between the output of the divider 761 and a predetermined reference voltage is obtained, and the gap length is controlled based on the difference between the output of the divider 761 and the predetermined reference voltage. Therefore, the gap length can be controlled based on the ratio of the power supply voltage and the average voltage, and the NC device 11 can perform multiaxial gap control, and the reference voltage can be easily changed. Therefore, by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage, even if the power supply voltage is changed during electric discharge machining, the electric discharge machining does not become unstable or abnormal machining occurs. In addition, stable electrical discharge machining can be maintained. Further, the most efficient processing condition can be selected with respect to the power supply voltage, and the accuracy is improved, so that the reproducibility is enhanced. Further, the NC device 11 enables multi-axis control. Since the resolution is lower than that of reading the conventional average voltage with an A / D converter, the cost is low.

By the way, in each of the above-mentioned embodiments, the embodiment of the die-sinking electric discharge machine has been described. However, when the present invention is carried out, a wire-cut electric discharge machine having a common basic electric discharge machining technique is used. It can also be implemented.

[0039]

According to the electric discharge machining apparatus of the first aspect, the power supply voltage applied to the gap between the workpiece and the electrode arranged facing the workpiece and the power supply voltage applied to the gap. An average voltage of the voltages is detected, and the gap length is controlled based on the difference between the ratio of the power supply voltage and the average voltage and a predetermined reference voltage. Therefore, by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage, even if the power supply voltage is changed during electric discharge machining, the electric discharge machining does not become unstable or abnormal machining occurs. In addition, stable electrical discharge machining can be maintained. Further, there is an effect that the most efficient processing condition can be selected for the power supply voltage.

According to a second aspect of the electric discharge machining apparatus of the present invention, there are provided a power supply voltage applied to a gap between a workpiece and an electrode arranged to face the workpiece and a voltage applied to the gap. An average voltage is detected, a ratio between the power supply voltage and the average voltage is obtained by a divider, a difference between the output of the divider and a predetermined reference voltage is converted into digital and input to an NC device, and the NC device is used to perform the operation. Since the gap length is controlled based on the difference between the output of the divider and the predetermined reference voltage, the gap length can be controlled based on the ratio between the power supply voltage and the average voltage.
The C device enables multi-axis clearance control. Therefore, by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage, even if the power supply voltage is changed during electric discharge machining, the electric discharge machining does not become unstable or abnormal machining occurs. In addition, stable electrical discharge machining can be maintained. Further, the most efficient processing condition can be selected for the power supply voltage. Furthermore, the NC device enables multi-axis control. Since the resolution is lower than that of reading the conventional average voltage by the A / D converter, there is an effect that the cost is low.

According to a third aspect of the electric discharge machining apparatus of the present invention, there are provided a power supply voltage applied to the gap between the work piece and an electrode arranged to face the work piece, and a voltage applied to the gap. The average voltage is detected, the ratio of the power supply voltage and the average voltage is obtained by a divider, the output of the divider is converted into digital and input to an NC device, and the NC device outputs the output of the divider and a predetermined value. Since the gap length is controlled based on the difference between the reference voltage and the output of the divider and a predetermined reference voltage, the gap length is calculated based on the ratio of the power supply voltage to the average voltage. Can be controlled, and multi-axis gap control can be performed by the NC device, and the reference voltage can be easily changed. Therefore, by controlling the gap length based on the ratio of the average voltage of the gap to the power supply voltage, even if the power supply voltage is changed during electric discharge machining, the electric discharge machining does not become unstable or abnormal machining occurs. In addition, stable electrical discharge machining can be maintained. Further, the most efficient processing condition can be selected with respect to the power supply voltage, and the accuracy is improved, so that the reproducibility is enhanced. Furthermore, the NC device enables multi-axis control. Since the resolution is lower than that of reading the conventional average voltage by the A / D converter, there is an effect that the cost is low.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a die-sinking electric discharge machine of a first embodiment as an electric discharge machine of the present invention.

FIG. 2 is a circuit configuration diagram showing a die-sinking electric discharge machine of a second embodiment as an electric discharge machine of the present invention.

FIG. 3 is a circuit configuration diagram showing a die-sinking electric discharge machine of a third embodiment as an electric discharge machine of the present invention.

FIG. 4 is a flow chart for performing servo control of the NC device of the die-sinking electric discharge machine according to the third embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional die-sinking electric discharge machining apparatus for fine machining such as fine hole machining.

FIG. 6 is a circuit configuration diagram of a conventional die-sinking electric discharge machine.

[Explanation of symbols]

1 electrode, 2 workpiece, 4 servo motor, 6 general-purpose servo amplifier, 7 servo reference circuit, 8 electrolytic capacitor, 9 power supply, 10 current limiting resistor, 762 voltage source voltage detection circuit, 763 average gap voltage Detection circuit, 761 divider, 11 NC device, 12 A / D converter, 13 Reference voltage setting device.

Claims (3)

[Claims] 1. A voltage is applied to a gap between a work piece and an electrode arranged so as to face the work piece to perform electric discharge machining on the work piece, and to apply to the gap during the electric discharge machining. In an electric discharge machining apparatus that controls a gap length by moving one or more of the workpiece and the electrode based on the averaged voltage, a power source voltage applied to the gap and a voltage applied to the gap. Of the power supply voltage and the average voltage is obtained by a divider, and the gap length is controlled based on the difference between the output of the divider and a predetermined reference voltage. apparatus. 2. A voltage is applied to a gap between a work piece and an electrode arranged to face the work piece to perform electric discharge machining on the work piece, and to apply to the gap during the electric discharge machining. In an electric discharge machining apparatus that controls a gap length by moving one or more of the workpiece and the electrode based on the averaged voltage, a power source voltage applied to the gap and a voltage applied to the gap. Of the power supply voltage and the average voltage are obtained by a divider, the difference between the output of the divider and a predetermined reference voltage is converted into digital and input to the NC device, and then the NC device is used. An electric discharge machining apparatus, wherein a gap length is controlled based on a difference between an output of the divider and a predetermined reference voltage. 3. A voltage is applied to a gap between a work piece and an electrode arranged so as to face the work piece to perform electric discharge machining on the work piece, and to apply to the gap during the electric discharge machining. In an electric discharge machining apparatus that controls a gap length by moving one or more of the workpiece and the electrode based on the averaged voltage, a power source voltage applied to the gap and a voltage applied to the gap. Of the power supply voltage and the average voltage are obtained by a divider, the output of the divider is converted into digital data and input to an NC unit, and the NC unit outputs the output of the divider and a predetermined value. And a gap length is controlled based on a difference between the output of the divider and a predetermined reference voltage.