JPH08118146A - Power control device for wire electric discharge machine - Google Patents

Abstract

PURPOSE: To improve the reliability of wire severance preventing technique and also machining speed. CONSTITUTION: A power control device for a wire electric discharge machine is provided with an electric discharge pulse detecting part 12 for detecting a short-circuit state between a workpiece 2 and a wire electrode 1, an abnormal state detecting part 13 for discriminating an abnormal state from the detection result of the electric discharge pulse detecting part 12, and an energy control part 14 for adding the energy value of electric discharge pulses within the specified time and stopping the supply of pulse voltage so that the added result of the energy value does not exceed the specified energy value during a period of abnormality being discriminated by the abnormal state detecting part 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machine, and more particularly to a power supply controller for a wire electric discharge machine including a machining power supply for preventing wire breakage and a control circuit therefor.

[0002]

2. Description of the Related Art In a power supply control device for a wire electric discharge machine, a very short pulse obtained by controlling ON / OFF of a switching element at very short intervals in order to supply a machining current having a high peak value. The width improves the processing speed. In general, a process of applying a tension of several hundred g to several kg is performed on a thin wire electrode in order to maintain the processing accuracy, so that there is a maximum current value that can be applied to the wire electrode. Disconnection occurs. Therefore, in order to prevent the occurrence of disconnection, it is important to control the processing energy during processing to be equal to or less than the disconnection limit value.
The techniques described in JP-A No. 2-19322 and JP-A No. 64-5724 can be mentioned.

FIG. 17 is a block diagram showing a schematic structure of a conventional wire electric discharge machine, and FIG. 18 is a machining current waveform diagram for explaining the operation of the conventional wire electric discharge machine. In FIG. 17, 1 is a wire electrode, 2 is a workpiece, 3 is a first DC power supply, 4 is a switching element, the positive electrode of the first DC power supply 3 is connected to the workpiece 2, and the negative electrode is the switching element 4. The wire electrode 1 is connected in series. Further, 5 is a second DC power supply, 6 is a diode, and the second DC power supply 5 is connected in parallel to the series circuit of the first DC power supply 3 and the switching element 4 via the diode 6. In this case, the second DC power supply 5 is connected to the work piece 2 in the opposite polarity to the first DC power supply 3, and the diode 6 is connected to the second DC power supply 5 in the opposite direction. Reference numeral 7 is a discharge start detection circuit, which detects that a discharge has occurred in the machining gap between the wire electrode 1 and the workpiece 2, and outputs a signal. Reference numeral 8 denotes a pulse control circuit, which turns off the switching element 4 after receiving a signal from the discharge start detection circuit 7, that is, after the time t1 from the start of the discharge, and then puts the switching element 4 into a rest state for a predetermined time and then switches the switching element again. ON / OFF switching control for turning on 4 is performed. Next, reference numeral 9 denotes an arithmetic circuit, which determines the time width of the signal corresponding to the rising time t1 of the waveform of a single or a plurality of discharge currents within a constant time T of the pulse signal from the pulse control circuit 8 to the switching element 4. The waveform of the discharge current Ip determined by the inductance of the current-carrying line in the pulse discharge circuit and the voltages of the first DC power supply 3 and the second DC power supply 5 is added to a value obtained by squaring and adding and dividing the value by the constant time T. A value (average machining current) multiplied by the specified constant K is calculated. Reference numeral 10 denotes a comparison circuit, which is the time t2 until the discharge current Ip determined by the rising time t1 of the discharge current waveform decreases when the output signal of the arithmetic circuit 9 exceeds a predetermined limit current value, or the discharge current At least one of the times t3 from when the waveform starts to fall to when the next machining voltage is applied to the machining gap is controlled.

Next, the operation of the conventional wire electric discharge machine will be described. The switching element 4 is the pulse control circuit 8
When it is turned on by the pulse signal from, the machining voltage is applied to the machining gap formed by the wire electrode 1 and the workpiece 2, and intermittent discharge is generated, and the workpiece 2 is processed by the discharge. . Here, when arc discharge occurs in the machining gap, the discharge start detection circuit 7 detects it and gives a signal to the pulse control circuit 8. The pulse control circuit 8 turns off the switching element 4 at time t1 after applying the signal, turns off the switching element 4 and then turns on the switching element 4 at time t3. After that, this is repeated to perform on / off switching control of the switching element 4. The waveform of the discharge current supplied to the machining gap at this time is, as shown in FIG. 18, a triangular wave due to the influence of the inductance of the current-carrying line when the resistance of the current-carrying line (current-carrying line) is small. Become. Since the inclinations α and β of the triangular wave and the time t1 are generally values peculiar to the apparatus, the amount of electricity i per 1 waveform (triangular wave) of the discharge current is the time t1 from the start of discharge until the switching element 4 is turned off. It will be proportional to the square of. Therefore, the arithmetic circuit 9 squares the time width of the signal corresponding to the rising time t1 of the waveforms of the plurality of discharge currents within the constant time T of the pulse signal supplied from the pulse control circuit 8 to the switching element 4. And add and add it for the fixed time T
Then, a value (average machining current) is calculated by multiplying this by the constant K. And the output signal of the arithmetic circuit 9,
That is, the comparison circuit 10 compares whether or not the average machining current exceeds the limit current value of the wire electrode 1, and when the average machining current exceeds the limit current value of the wire electrode 1, the rise time of the waveform of the discharge current. At least the decrease of t1 or the increase of the time t3 from when the waveform of the discharge current starts to fall until the next machining voltage is applied to the machining gap,
Control either one. As a result, the average machining current during machining is constantly controlled so as not to exceed the limit current value of the wire electrode 1, and wire breakage of the wire electrode 1 is prevented.

[0005]

However, although the limiting current value exists due to the difference in the material, diameter, etc. of the wire electrode 1, the machining conditions are generally not uniform, and for example, the ejection efficiency of the machining fluid is poor. When the end surface, the corner portion, and the plate thickness of the workpiece 2 change, the limiting current value decreases. However, there is nothing disclosed in the above-mentioned conventional example regarding the technique of changing and controlling the limiting current value according to these situations. Therefore, in the above-mentioned conventional example, in order to completely prevent disconnection of the wire in processing a step or the like of the workpiece 2, the limit current value (energy) is set in accordance with the plate thickness, or the plate thickness is set. Although it is possible to set the limiting current value to the minimum part, the former requires to obtain the limiting current value for each plate thickness in advance and to command each plate thickness of the processed part with a program etc. Is inefficient. In the latter case, when the processing situation is good, the processing speed is significantly reduced and the processing efficiency is reduced.

Therefore, an object of the present invention is to provide a power supply control device for a wire electric discharge machine that improves the reliability of wire breakage prevention in a wire electric discharge machine and further improves the machining speed.

[0007]

According to a first aspect of the present invention, there is provided a power supply control device for a wire electric discharge machine, which is a total machining pulse per constant time of a short circuit pulse conducted in a state where no electric discharge is generated between a wire electrode and a workpiece. Depending on the short-circuit pulse ratio or the normal discharge pulse ratio to the total machining pulse per fixed time of the no-load time from the application of the pulse voltage between the wire electrode and the workpiece to the occurrence of discharge for a certain time or longer The processing energy value is changed.

According to a second aspect of the present invention, there is provided a power supply control device for a wire electric discharge machine, which detects a short circuit between a workpiece and a wire electrode, and a short circuit detecting unit which detects an abnormal state. An abnormal state detecting means for determining,
The period during which the abnormal state detecting means determines that the abnormality is
A machining energy control means for adding the energy values of the discharge pulses within a predetermined time and stopping the supply of the pulse voltage so that the addition result does not exceed the predetermined energy value.

The abnormal state detecting means of the power supply control device for the wire electric discharge machine according to claim 3 is a discharge pulse counting means for counting the discharge pulses generated in the workpiece and the wire electrode, and the discharge pulse counting means. Means and a short circuit pulse ratio calculating means for calculating the ratio of the short circuit pulse from the short circuit detecting means, and a short circuit pulse ratio comparing means for comparing the calculation result of the short circuit pulse ratio calculating means with a predetermined short circuit pulse ratio. It is to determine the state.

According to a fourth aspect of the present invention, there is provided a power supply control device for a wire electric discharge machine, wherein the discharge pulse counting means in the abnormal state detecting means of the third aspect applies a pulse voltage between the wire electrode and the workpiece. Total machining pulse counting means for counting the number of pulses per a certain period of time, and a no-load time from the application of the pulse voltage between the wire electrode and the workpiece to the occurrence of discharge of a pulse longer than a predetermined time This is a normal discharge pulse counting means for counting the number of pulses per fixed time.

According to a fifth aspect of the present invention, the abnormal state detecting means of the power supply control device for the wire electric discharge machine comprises no-load time detecting means for detecting a no-load time from application of the pulse voltage to the occurrence of discharge. From the normal discharge pulse counting means for counting pulses having a no-load time detected by the no-load time detecting means longer than a predetermined no-load time as compared with a predetermined time, the normal discharge pulse counting means and the short-circuit detecting means It is provided with a short circuit pulse ratio calculating means for calculating a ratio of short circuit pulses and a short circuit pulse ratio comparing means for comparing a calculation result of the short circuit pulse ratio calculating means with a predetermined short circuit pulse ratio to determine an abnormal state.

According to a sixth aspect of the present invention, the abnormal state detecting means of the power supply control device of the wire electric discharge machine is based on a first short circuit pulse ratio comparing means and the predetermined pulse ratio of the first short circuit pulse ratio comparing means. After the abnormal state is discriminated by the second short circuit pulse ratio comparison means for comparing with a small predetermined pulse ratio and the first short circuit pulse ratio comparison means, the abnormal state is released by the second short circuit pulse ratio comparison means. It is a thing.

According to a seventh aspect of the present invention, the short circuit pulse ratio comparing means of the power supply control device for the wire electric discharge machine has a predetermined short circuit pulse ratio to be compared with the calculation result of the short circuit pulse ratio calculating means. Is a function of.

The machining energy control means of the power supply control device for the wire electric discharge machine according to claim 8 adds the energy values of the discharge pulses within the predetermined time, and calculates the average energy within the predetermined time from the addition result. The average energy calculating means and the addition result of the energy value of the discharge pulse during the period when the abnormality is detected by the abnormal state detecting means sets a threshold value based on the calculation result of the average energy calculating means immediately before the abnormality is determined. The supply of the pulse voltage is controlled so as not to exceed the limit.

[0015]

According to the first aspect of the present invention, by detecting the short circuit pulse ratio or the normal discharge pulse ratio, it is possible to accurately detect an unstable portion such as a step of the workpiece or a change in the plate thickness, and based on the result, the machining is performed. By controlling so as not to exceed the limit energy level according to the state, it is possible to always perform processing at the limit energy level.

According to the second aspect of the present invention, by detecting the short circuit pulse ratio or the normal discharge pulse ratio, it is possible to accurately detect an unstable portion such as a step of the workpiece or a change in the plate thickness, and based on the result, the machining is performed. By controlling so that the limit energy level according to the condition is not exceeded, it is possible to always process at the limit energy level, and determine the abnormal state by the detection result of the short circuit state, and when it is determined, the processing energy does not exceed the predetermined value. Stop the pulse voltage supply.

According to the present invention, the discharge pulse and the short circuit pulse supplied are respectively counted, and the short circuit pulse ratio is calculated.

According to the present invention, the number of short circuit pulses is calculated from the supplied total machining pulses and the normal discharge pulse, and the short circuit pulse ratio is calculated.

According to a fifth aspect of the present invention, the machining pulse and the short circuit pulse having a predetermined no-load voltage or higher are counted, and the short circuit pulse ratio is calculated.

In the sixth aspect, the abnormal state is set at a predetermined short circuit pulse ratio or higher, and the abnormal state is canceled at a predetermined short circuit pulse ratio or lower.

In the present invention, the predetermined short circuit pulse ratio to be compared is controlled as a function of the plate thickness of the workpiece.

In the eighth aspect, the supply of the pulse voltage is controlled so that the energy value based on the average energy immediately before the abnormal state is set is not exceeded.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply control device for a wire electric discharge machine according to an embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals and symbols as those of the conventional example and the respective examples show the same or corresponding components as those of the respective examples.

Example 1. FIG. 1 is an explanatory diagram for explaining the basic operation of the power supply control device for a wire electric discharge machine according to the first embodiment of the present invention. In particular, FIG. 1A shows that the plate thickness of the workpiece 2 changes. Explanatory drawing showing the relationship between the plate thickness and the machining position in the portion, FIG. 1B is an explanatory view showing the relationship between the machining position and the machining energy in the portion where the plate thickness of the workpiece 2 changes 1
(C) shows the machining position and the ratio of the short-circuit pulse to the total machining pulse per constant time of the short-circuit pulse and the pulse of the no-load time longer than a predetermined time (hereinafter, simply referred to as "normal discharge pulse") per constant time. It is explanatory drawing which showed the relationship with the normal discharge pulse ratio with respect to the total machining pulse.
Here, the short circuit means that the wire electrode 1 is in direct contact with the workpiece 2 due to vibration of the wire electrode 1 or the presence of machining sludge or the like in the gap between the wire electrode 1 and the workpiece 2. The state of being in electrical contact, that is, the wire electrode 1
And the work piece 2 are electrically connected to each other in a state where no electric discharge is generated.

From FIGS. 1 (a) and 1 (b), under the "machining condition 1", there is a break in the step portion, and there is a limit energy level with respect to the plate thickness of the workpiece 2, which is similar to the step portion. It can be seen that the processing energy increases in the part where the processing becomes unstable. Further, in FIGS. 1 (a) and 1 (c), the short-circuit pulse ratio rapidly increases at a portion where the plate thickness changes, and the short-circuit pulse ratio at a small plate thickness portion becomes large. It is higher than the short circuit pulse ratio. On the other hand, it was found that the normal discharge pulse showed the opposite tendency to the short circuit pulse. In the above-mentioned state, when the no-load time is a pulse shorter than a predetermined time, a technique of supplying a pulse with a low current peak to prevent disconnection is already known. However, in such a measure, when a pulse having a no-load time shorter than a predetermined time is frequently generated such as a stepped portion, the current peak value is considerably small when the no-load time is short in order to obtain the effect of preventing disconnection. It is necessary to set the value, and during stable processing, the processing speed decreases and the processing efficiency decreases.

Further, in the case where pulses with a no-load time shorter than a predetermined time occur frequently, the energy value is suppressed because the energy is supplied at the initial stage of the discharge start. In the prior art, an increase in the energy value is detected. The accuracy will be reduced.

However, according to this embodiment, by detecting the short circuit pulse ratio or the normal discharge pulse ratio,
It can be confirmed that unstable parts such as steps of the workpiece and changes in the plate thickness can be accurately detected. Further, based on the result, it is possible to control so as not to exceed the limit energy level according to the processing state, and it is possible to always perform processing at the limit energy level. That is, the power supply control device of the wire electric discharge machine according to the present embodiment is a wire electric discharge machine that applies a pulse voltage between the workpiece 2 and the wire electrode 1 arranged to face the workpiece 2 to perform electric discharge machining. Electrode 1 in the machine power control device
Between the wire electrode 1 and the workpiece 2 showing the short circuit pulse ratio of the short circuit pulse conducted in a state in which no discharge is generated between the workpiece 2 and the workpiece 2 or the ratio of the short circuit pulse ratio to the total machining pulse per constant time. The machining energy value is changed according to the ratio of the normal discharge pulse to the total machining pulse per constant time of the no-load time from the application of the pulse voltage to the occurrence of discharge for a predetermined time or longer. Can be an embodiment corresponding to the claims.

Embodiment 2 FIG. FIG. 2 is a block diagram showing a wire electric discharge machine for explaining a power supply control device of the wire electric discharge machine according to the second embodiment of the present invention. In FIG. 2, 1
Is a wire electrode, 2 is a workpiece, 7 is a discharge start detection circuit that detects a machining voltage between electrodes, 8 is a pulse control circuit that controls a switching operation of a machining power source 11, 11 is a wire electrode 1 and a workpiece It is a power supply for processing that supplies a discharge current pulse between the two. Reference numeral 12 is a discharge pulse detection unit that detects a short-circuit pulse, 13 is an abnormal state detection unit that determines whether the discharge state is abnormal or normal based on the output result of the discharge pulse detection unit 12, and 14 is an abnormal output signal of the abnormal state detection unit 13. Is an energy control unit that controls the processing energy during the period when is output. Further, 20 is a table on which the workpiece 2 is placed, 21a and 21b are X-axis and Y-axis drive motors for positioning the relative positions of the wire electrode 1 and the workpiece 2, and 22 is X-axis drive motors 21a and Y. An axis drive control section for controlling the axis drive motor 21b, 23 an average processing voltage detection section for detecting an average processing voltage, 24 an NC for sending an axis movement command and a processing condition parameter to the axis drive control section 22 and the pulse control circuit 8. It is a control unit.

FIG. 3 is a pulse control circuit 8 for explaining a power supply controller for a wire electric discharge machine according to a second embodiment of the present invention.
FIG. In FIG. 3, 1101 is a DC power supply (E1), 1102 is a sub switching element (TR).
1) 1103 is a current limiting resistor, 1104 is a diode, and the negative electrode of the DC power supply 1101 is the diode 110.
4, the anode of the diode 1104 is connected to the wire electrode 1, the positive electrode of the DC power supply 1101 is connected to one end of the current limiting resistor 1103, and the other end of the current limiting resistor 1103 is connected to the auxiliary switching element 1102. The sub switching element 1102 is connected to the drain, the source is connected to the workpiece 2, and the gate is connected to the pulse control circuit 8. Further, 1105 is a DC power source (E2), 11
Reference numeral 06 is a main switching element (TR2), 1107 is a diode, and the negative electrode of the DC power supply 1105 is the diode 1
107, the anode of the diode 1107 is connected to the wire electrode 1, the positive electrode of the DC power supply 1105 is connected to the drain of the main switching element 1106, and the source of the main switching element 1106 is the workpiece 2
The gate is connected to the pulse control circuit 8. Reference numeral 1108 denotes a DC power source, 1109 denotes a diode, the positive electrode of the DC power source 1108 is connected to the anode of the diode 1109, the cathode of the diode 1109 is connected to the wire electrode 1, and the positive electrode of the DC power source 1108 is connected to the workpiece 2. It is connected.

FIG. 4 is a circuit diagram showing details of the discharge pulse detector 12 and the abnormal state detector 13 of the second embodiment of the present invention. In the figure, in the discharge pulse detector 12, 1
201 is a comparison circuit, 1202 is an inverter circuit, 120
3 is an AND circuit, one input (-) of the comparison circuit 1201 is maintained at a predetermined voltage level V2 equal to or lower than the arc voltage, and the other input (+) is the inter-electrode voltage output Vg of the discharge start detection circuit 7. Is input and the voltage output between contacts Vg is V2
In the above case, the output becomes "1", and the voltage between contacts V
When g is less than V2, its output becomes "0". The output of the comparison circuit 1201 is connected to the input of the inverter circuit 1202, and the output of the inverter circuit 1202 is the AND circuit 1
The pulse signal S2 of the pulse control circuit 8 is input to the other input of the AND circuit 1203 and the other input of the AND circuit 1203, and when the pulse signal S2 driving the main switching element 1106 is "1", and Voltage between contacts Vg
Is less than the voltage V2, that is, the AND circuit 1
The output of 203 becomes "1".

Next, in the abnormal state detector 13,
01 is a counter [A], 1302 is a counter [B], 1
Reference numeral 303 is a match comparison circuit, 1304 is a sample number setter for setting a unit sample number N2 which is a threshold value of the count value of the counter 1302, 1305 is a match comparison circuit, 1306
Is a determination number setting device that sets a determination number N1 that is a threshold value for detecting an abnormality based on the count number of the counter 1301;
1307 is a latch circuit. The input of the counter 1301 is connected to the output of the AND circuit 1203 of the discharge pulse detector 12, and the input of the counter 1302 is the pulse control circuit 8.
The pulse signal S2 of the counter 1301 is received, the output of the counter 1301 is input to the A terminal of the match comparison circuit 1305, the B input of the match comparison circuit 1305 is input to the determination number setting unit 1306, and the output of the counter 1301 is set to the determination number. Bowl 1306
When the number becomes larger than the predetermined number N1 set in advance, the match comparison circuit 1305 outputs "1", and the output of the match comparison circuit 1305 is input to the D terminal of the latch circuit 1307. The output of the counter 1302 is input to the A terminal of the coincidence comparison circuit 1303, the B terminal of the coincidence comparison circuit 1303 is input to the sample number setter 1304, and is preset in the output of the counter 1302 and the sample number setter 1304. When the predetermined number N2 matches, the match comparison circuit 13
“1” is output from 03. The output of the coincidence comparison circuit 1303 is connected to the reset terminals of the counters 1301 and 1302, and when “1” is input, the counters 1301 and 1302 are reset, and the output thereof is input to the Cp terminal of the latch circuit 1307, The D input value of the latch circuit 1307 is latched at the timing of "0" to "1" of the input, and the abnormality detection signal is output from the Q terminal.

FIG. 5 is a circuit diagram showing details of the energy control unit 14 of the second embodiment of the present invention. In FIG. 5, 14
01 is an energy value conversion circuit, 1402 is an average energy value calculation circuit for calculating average energy of a predetermined cycle, 1403
Is an energy value addition circuit for adding energy values in a predetermined cycle, 1404 is a timer [A] for setting the calculation cycle of the average energy value calculation circuit 1402, and 1405 is a timer [B] for setting the addition cycle of the energy value addition circuit 1403. 1
406 is a latch circuit, 1407 is an energy value adding circuit 1
Reference numeral 1408 denotes an AND circuit that compares the output E of 403 with the output Eav of the average energy value calculation circuit 1402. The energy value conversion circuit 1401 inputs the pulse signal S2 of the pulse control circuit 8, converts the pulse width data of the pulse signal S2 into an energy value, and outputs the average energy value calculation circuit 1402 and the energy value addition circuit 1403. Are typing in. Further, the timer 1404 is connected to the reset terminal of the average energy value calculation circuit 1402, the timer 1405 is connected to the reset terminal of the energy value addition circuit 1403, and the output of the average energy value calculation circuit 1402 is input to the data terminal of the latch circuit 1406 and latched. Abnormality detection unit 13 input to the trigger terminal of the circuit 1406
Latch operation is performed by the rise of the output of. The coincidence comparison circuit 1407 receives the output of the energy value addition circuit 1403, the other input receives the output of the latch circuit 1406, and the output E of the energy value addition circuit 1403 is the output Eav of the average energy value calculation circuit 1402. Latch circuit 140
When it is larger than the value latched by 6, "1" is output. Furthermore, the coincidence comparison circuit 1407 and the abnormality detection unit 13 are connected to the input of the AND circuit 1408, and the AND circuit 1408 outputs a pulse stop signal to the pulse control circuit 8.

Next, the operation of the second embodiment will be described. Figure 2
In, the machining path information and machining electrical condition parameters are input to the NC control unit 24 from an NC program or an operation panel (not shown). The input processing electrical condition parameter is output to the pulse control circuit 8. Based on this parameter, the pulse control circuit 8 generates a drive pulse signal having a predetermined current peak value, pulse width, and rest time, and controls the machining power supply 11. The machining power supply 11 is driven by this drive pulse signal, and a predetermined current pulse is supplied to the machining gap between the wire electrode 1 and the workpiece 2 which are held by the wire guide above and below the workpiece 2. Generally, water or a water-based machining liquid is supplied to the machining gap, and the electric discharge machining is performed in the state where the machining liquid is supplied. Next, the average machining voltage detection unit 23 detects the average voltage during machining, and based on this average machining voltage, the electrode 1 or the workpiece is maintained so that the relative position between the electrode 1 and the workpiece 2 is kept constant. 2 feed control is performed. That is, when the detected average voltage is equal to or higher than a predetermined value, the feed speed of the electrode 1 or the workpiece 2 is increased, and when the average voltage is equal to or lower than the predetermined value, the feed speed of the electrode 1 or the workpiece 2 is decreased. Let The feed speed of the electrode 1 or the workpiece 2 is calculated by the NC controller 24, and the positioning command is output to the axis drive controller 22 based on the machining path information. Positioning control of the table 20 is performed by the drive motor 21b, and the table 20 is processed into a desired shape.

Next, FIG. 6 is a timing chart for explaining the operation of the pulse control circuit 8 and the discharge pulse detector 12 of FIGS. In the figure, S1 is a pulse signal for driving the sub-switching element 1102, S2 is a pulse signal for driving the main switching element 1106, and S3 is a pulse signal S1 for driving the sub-switching element 1102 until "1" after the discharge is started. Time and predetermined time T
It is a pulse signal that clearly indicates the magnitude relationship with c. First, the pulse signal S1 for driving the sub-switching element 1102 at the timing of starting machining is set to "1", the pulse signal S3 is set to "0", and the sub-switching element 1102 is turned on by the pulse signal S1. 1, the voltage E1 of the DC power supply 1101 is applied to the workpiece 2. Further, after the pulse signal S1 for driving the sub switching element 1102 is set to "1", a predetermined time Tc
When it becomes the above, the pulse signal S3 is set to "1". First, when the discharge is started, the divided voltage value Vg by the resistors 71 and 72 is compared with the set voltage V2 to detect the start of the discharge, and the pulse S1 is set to "0" at this timing, and The signal S2 is set to "1" to drive the main switching element 1106, and the DC power supply 1105 starts supplying the machining current between the electrodes. At this time, when the pulse signal S3 is "0", the pulse signal S2 is set to "1" for a predetermined time ON1, and when the pulse signal S3 is "1", the pulse signal S2 is set to "1" for a predetermined time ON2.
The pulse signal S2 is set to "0", the supply of the machining current is stopped, and after the pause time OFF period has elapsed, the pulse signal S
The operation of setting 1 to “1” is repeated. Generally, when the period Td in which the pulse signal S1 is "1" is compared with the predetermined time Tc, and when Td≤Tc (immediate discharge pulse), ON1, Td>
When Tc (normal discharge pulse) is selected, ON2 is selected, and by setting ON1 <ON2, the processing energy is increased and the processing speed can be improved. At this time, the one shown in the figure has the same rising and falling edges with a triangular wave, but in reality, the falling edge becomes steep, and the discharge current waveform becomes a pulse waveform with a high peak value and a short pulse width. That is, the voltage E1 is driven by driving the sub switching element 1102.
After the application of the electric current, a minute current limited by the resistor 1103 flows into the machining gap with the start of the discharge, and when the electric discharge is detected, the main switching element 1106 is driven to raise the current on the low impedance circuit from the power source E2, and further, the main switching This is because, after the driving of the element 1106 is stopped, a current flows through the DC power supply 1108 and the power supply 1108 immediately falls.

Further, the discharge pulse detector 12 compares the divided voltage value Vg of the voltage between contacts with the voltage level V2 set to a value lower than the arc voltage to determine whether the discharge state is a short circuit state or not. To do. Here, the comparison circuit 120
A pulse that becomes "1" when a machining current is supplied in a short circuit state (short circuit) by an output that is the logical product of the output obtained by inverting the output of 1 in the inverter circuit 1202 and the pulse signal S2 that drives the main switching element 1106. Pulse) can be obtained. In this way, the machining pulse, normal pulse,
It can be distinguished as an immediate discharge pulse or a short circuit pulse.

Next, FIG. 7 is a timing chart showing the operation of the abnormal state detector 13. 4 and 7, a short circuit pulse is input to the counter 1301 and a pulse signal S2 for driving the main switching element 1106 is input to the counter 1302 to count the total number of processing pulses. At the same time as the counter 1301 counts the number of short-circuit pulses, the counter 1302 counts the total number of processing pulses. The coincidence comparison circuit 1305 outputs "1" when the count number of the short circuit pulse becomes larger than the number N1 set by the determination number setting unit 1306. On the other hand, in the coincidence comparison circuit 1303, when the count value of the total machining pulses coincides with the number N2 set by the sample number setting unit 1304, "1" is set as the coincidence output, and the coincidence comparison circuit 1303 outputs the coincidence at the rising edge of the pulse. The counter 1301 and 1302 are reset while being latched by the output of the comparison circuit 1303. By the coincidence comparison circuit 1303, the ratio of the short-circuit pulse to the predetermined number of total machining pulses (short-circuit pulse ratio) can be obtained, and when the ratio exceeds the predetermined ratio, an abnormality detection signal can be output.

Next, FIG. 8 is a timing chart showing the operation of the energy control unit 14. In FIG. 5 and FIG. 8, the energy value conversion circuit 1401 drives the pulse signal S2 for driving the main switching element 1106 of the pulse control circuit 8.
Based on the ON time (see ON1 or ON2 in FIG. 6), the energy is converted into a processing energy value per current pulse and output. Here, the current waveform as shown in FIG. 6 has a current peak value specific to the circuit with respect to the impedance and the current pulse width in the circuit, and the machining energy value per discharge pulse is the arc potential. And the integrated value of the current pulse. In addition, the energy control unit 14 in the case of implementing the present invention is not limited to the processing power supply 11 shown in FIG. 2 and can obtain the energy value as described above.

By the way, the energy value adding circuit 1403
Starts the addition of the energy value E for each machining pulse by the pulse given in the set cycle T1 of the timer [B] 1405, and outputs the addition result to the coincidence comparison circuit 1407.
Further, the average energy value calculation circuit 1402 uses the timer [A].
The addition of the energy value E for each machining pulse is started by the pulse given in the cycle T2 (= n × T1) of the set time of 1404, and the addition result is divided by n at the next pulse and the division result is latched at the same time. Latch circuit 1
The average energy value Eav can be output to 406.
The latch circuit 1406 latches the output of the average energy value calculation circuit 1402 at the timing when the abnormality detection signal output from the abnormal state detection unit 13 becomes “1”, and the energy value is calculated from the latched average energy value Eav. When the output E of the adder circuit 1403 becomes large and when the output of the abnormal state detection unit 13 is "1", the AND circuit 140
Reference numeral 8 outputs a pulse stop signal to the pulse control circuit 8 to stop driving only the main switching element 1106 or both the sub switching element 1102 and the main switching element 1106.

According to the second embodiment, when the plate thickness of the work piece 2 is suddenly changed or the wire breakage at the corner portion is likely to occur, the increase of the short-circuit pulse ratio is used as the abnormality detection signal, and the abnormality is detected. Since the machining energy value can be controlled so as not to exceed the average energy value immediately before the state, wire breakage can be reliably prevented when the discharge frequency increases with an increase in the short-circuit pulse, that is, when the machining energy increases. In the present embodiment, during the period when the abnormality detection signal becomes “1”, at least one of the ON times ON1 and ON2 of the main switching element 1106 is reduced, and as a result, the machining current peak value is reduced, The disconnection prevention effect can be improved. In addition, the latch circuit 140
The average energy value Eav is output to 6, but when the jetting effect of the machining fluid is particularly bad, such as in a portion having a large step on the workpiece 2, it is necessary to further reduce the energy value. Is output by multiplying the average energy value Eav by a predetermined coefficient smaller than "1".
The disconnection prevention effect of the wire electrode 1 can be improved.

That is, the power supply control device of the wire electric discharge machine according to the present embodiment performs electric discharge machining by applying a pulse voltage between the work piece 2 and the wire electrode 1 arranged to face the work piece 2. In a power supply control device of a wire electric discharge machine, a short circuit pulse ratio to a total machining pulse of a short circuit pulse conducted in a state in which no electric discharge is generated between the wire electrode 1 and the workpiece 2 or a short circuit pulse ratio opposite to the short circuit pulse ratio. Depending on the ratio of the normal discharge pulse to the total machining pulse per constant time, the no-load time from the application of the pulse voltage between the wire electrode 1 showing the characteristics and the workpiece 2 to the occurrence of discharge is longer than the predetermined time , The processing energy value is changed, and this can be an embodiment corresponding to the claims. According to the present embodiment, by detecting the short circuit pulse ratio or the normal discharge pulse ratio, it is possible to accurately detect an unstable portion such as a step of the workpiece or a change in the plate thickness. Further, based on the result, it is possible to control so as not to exceed the limit energy level according to the processing state, and it is possible to always perform processing at the limit energy level.

Further, the power supply control device of the wire electric discharge machine of the present embodiment performs electric discharge machining by applying a pulse voltage between the work piece 2 and the wire electrode 1 arranged to face the work piece 2. In a power supply control device for a wire electric discharge machine, an abnormal state is detected based on a short-circuit detection unit including a discharge pulse detection unit 12 that detects that the workpiece 2 and the wire electrode 1 are in a short-circuit state and the detection result of the short-circuit detection unit. The timer [B] 140 is used for the abnormal state detecting unit including the abnormal state detecting unit 13 for determining and the period in which the abnormal state detecting unit determines the abnormal state.
The machining energy control unit 14 that adds the energy values of the discharge pulses within the predetermined time set to 5 and stops the supply of the pulse voltage so that the addition result does not exceed the predetermined energy value.
And a machining energy control means, which corresponds to an embodiment corresponding to the claims. Therefore, by detecting the short-circuit pulse ratio, it is possible to accurately detect unstable parts such as steps of the work piece and changes in the plate thickness, and based on the result, do not exceed the limit energy level according to the processing state. It can be controlled and can always be processed at the limit energy level. Therefore, when the plate thickness of the work piece 2 suddenly changes or the wire breakage at the corner portion is likely to occur, the increase in the ratio of the short-circuit pulse obtained from the short-circuit detection means is used as the abnormality detection signal, and the abnormal state is detected. The machining energy value can be controlled so as not to exceed the immediately preceding average energy value, and wire breakage can be reliably prevented when the discharge frequency increases with an increase in the short-circuit pulse, that is, when the machining energy increases.

In particular, the abnormal state detecting means of the present embodiment is a discharge pulse counting means composed of a counter [A] 1301 for counting the discharge pulses generated in the workpiece 2 and the wire electrode 1, and a discharge pulse counting means. And discharge pulse detector 1
The counter [B] 1302 and the coincidence comparison circuit 1303 for calculating the ratio of the short-circuit pulse from the short-circuit detecting means consisting of 2
And a short-circuit pulse ratio calculating means comprising a sample number setting device 1304, and a coincidence comparing circuit 1305 comparing the calculation result of the short-circuit pulse ratio calculating device with a predetermined short-circuit pulse ratio set by the determination number setting device 1306. And a ratio comparison means, which corresponds to an embodiment corresponding to the claims. Therefore, since the counter [A] 1301 that counts the discharge pulse and the counter [B] 1302 that calculates the ratio of the short-circuit pulse count the pulse, the abnormal state can be detected with high sensitivity.

Further, the processing energy control means 1 of this embodiment
4 adds the energy value of the discharge pulse within a predetermined time,
Energy value conversion circuit 1401 and average energy value calculation circuit 1 for calculating the average energy within a predetermined time from the addition result
During the period in which the average energy calculating means composed of 402 and the abnormal state detecting means composed of the abnormal state detecting section 13 are determined to be abnormal, from the addition result of the energy values of the discharge pulse,
The latch circuit 14 does not exceed the threshold value based on the calculation result of the average energy calculating means immediately before it is determined to be abnormal.
06, coincidence comparison circuit 1407, and AND circuit 1408
According to the present invention, the supply of the pulse voltage is stopped according to the present invention. Therefore, when the supply of the pulse voltage can be controlled so as not to exceed the energy value based on the average energy immediately before the abnormal state is set, and the workpiece 2 or the like continuously changes the plate thickness,
Alternatively, the machining can be performed according to the efficiency of the optimum electric discharge machining.

Example 3. In the second embodiment, the output of the discharge pulse detection unit 12 to the abnormal state detection unit 13 is the short-circuit pulse and the total machining pulse, but the short-circuit pulse and the normal discharge pulse may be similarly output. FIG. 9 is a block diagram showing another example of the abnormal state detection circuit 13 in the third embodiment of the present invention. In particular, in this embodiment, only the differences from the above embodiments will be described. In the figure, 12 is a discharge pulse detection unit, 1204 is a 3-input AND circuit,
The pulse signal S2 for driving the main switching element 1106 of the pulse control circuit 8, the on-time switching pulse signal S3 of the main switching element 1106, and the comparison circuit 1201 are input, and the output thereof is the counter [B] 1032 of the abnormal state detection unit 13. It is input. FIG. 10 is an explanatory diagram for explaining the operation of the discharge pulse detector 12. In the case of a normal discharge pulse, the pulse of the AND circuit 1203 is output, and in the case of a short circuit pulse, the pulse of the AND circuit 1204 is output. By inputting the output of the discharge pulse detector 12 to the abnormal state detector 13, the abnormality detection signal can be obtained as a ratio of the short circuit pulse to the normal discharge pulse.

In the third embodiment, in the processing including the step such that the plate thickness of the workpiece 2 becomes small, the workpiece 2
Since the number of short-circuit pulses increases and the number of normal discharge pulses decreases in the step portion, the abnormal state can be detected with higher sensitivity by obtaining the ratio of the short-circuit pulse to the normal discharge pulse. That is, as shown in the short-circuit pulse / normal discharge pulse-time characteristic diagram of the present embodiment of FIG. 11, there is an abrupt change point between the large thickness and the small thickness of the workpiece 2. I understand.

As shown in FIG. 1, the short-circuit pulse ratio of the short-circuit pulses conducted in a state in which no discharge is generated between the wire electrode 1 and the workpiece 2 to the total machining pulse per constant time, the wire electrode 1 and the workpiece. The change of the normal discharge pulse ratio to the total machining pulse per constant time of the pulse whose no-load time is longer than the predetermined time from the application of the pulse voltage between the object 2 and the occurrence of discharge is similar to the inverse characteristic. Therefore, as in the first embodiment, the abnormal state detection means including the abnormal state detection unit 13 of the above embodiment detects the no-load time from the application of the pulse voltage to the occurrence of discharge. Load time detection means, and a pulse counting means for counting pulses whose no-load time detected by the no-load time detection means is longer than a predetermined no-load time in comparison with a predetermined time,
The short-circuit pulse ratio calculating means for calculating the ratio of short-circuit pulses from the pulse counting means and the short-circuit detecting means, and the short-circuit pulse ratio comparing means for comparing the calculation result of the short-circuit pulse ratio calculating means with a predetermined short-circuit pulse ratio. It is also possible, which corresponds to an embodiment corresponding to the claims.

Example 4. In the second to third embodiments, the number of determinations of the count value of the short circuit pulse is one type, but the number of determinations may be set to two types, large and small, to provide hysteresis. FIG. 12 is a block diagram illustrating another example of the abnormal state detection unit 13. In particular, in this embodiment, only the differences from the above embodiments will be described.

In the figure, 1310 is a coincidence comparison circuit, 1
311 is a judgment number NL setter that sets the number of Low level judgments, 1312 is a match comparison circuit, and 1313 is a judgment number NH setter that sets the number of High level judgments. The A input of the circuit 1312 is connected to the output of the counter 1310, the judgment number NL setter 1311 is connected to the B input of the match comparison circuit 1310, and the judgment number N is connected to the B input of the match comparison circuit 1312.
The H setter 1313 is connected. Further, 1314 is an inverter circuit, 1315 is a latch circuit, and 1316 is R.
-S flip-flop circuit, 1317 is a latch circuit. The A> B output of the match comparison circuit 1310 is input to the inverter circuit 1314, the output of the inverter circuit 1314 is connected to the D terminal of the latch circuit 1315, and the latch circuit 1315 outputs. The Cp terminal is connected to the coincidence terminal of the coincidence comparison circuit 1303, the Q terminal of the latch circuit 1315 is connected to the reset terminal of the flip-flop 1316, and the A> B output of the coincidence comparison circuit 1312 is similarly flip-flop 13.
Flip-flop 131 connected to 16 set terminals
The Q terminal of 6 is connected to the D terminal of the latch circuit 1317,
The coincidence output of the coincidence comparison circuit 1303 is the latch circuit 1317.
Of the latch circuit 1317 and an abnormality detection signal is output from the Q terminal of the latch circuit 1317.

The abnormal state detection unit 13 of the present embodiment includes a first short circuit pulse ratio comparison unit composed of a coincidence comparison circuit 1312 and a judgment number NH setter 1313 and the predetermined short circuit pulse ratio comparison unit. Second short circuit pulse ratio comparing means comprising a coincidence comparing circuit 1310 for comparing with a predetermined pulse ratio smaller than the pulse ratio and a judgment number NL setting device 1311;
After the abnormal state is discriminated by the first short-circuit pulse ratio comparison means, the abnormal state is canceled by the second short-circuit pulse ratio comparison means, which corresponds to the embodiment corresponding to the claims. Therefore, in the present embodiment, it is possible to set the number of judgments of the count value of the short-circuit pulse, large and small, to provide hysteresis.

FIG. 13 is a timing chart for explaining the operation of the abnormal state detector 13 in the fourth embodiment of the present invention. In the figure, the coincidence comparison circuit 1303 outputs "1" when the output of the counter [B] 1302, which is the count value of the total machining pulse, coincides with the number N2 set by the sample number setting unit 1304, and the counter [A] 1301 and the counter [B] 1302 are reset to determine the sampling cycle. On the other hand, the coincidence comparison circuit 1310 outputs "1" when the count number of the short circuit pulse becomes larger than the number NL set by the determination number NL setter 1311,
This inverted signal is input to the D terminal of the latch circuit 1315,
It latches at the rising edge of the coincidence output pulse, and the latch output is input to the reset of the flip-flop 1316. Further, the coincidence comparison circuit 1312 outputs "1" when the count value of the short circuit pulse becomes larger than the number NH set by the determination number NH setter 1313, and the flip-flop 1
316 input to the flip-flop 1316
The Q terminal is input to the D terminal of the latch circuit 1317, latched at the rising edge of the coincidence output pulse, and output as an abnormality detection signal.

As described above, by setting two kinds of determination values of the count value of the short-circuit pulse and providing the hysteresis, it is possible that the machining becomes unstable at a portion such as a step of the workpiece 2 where the machining state changes abruptly. In this case, erroneous detection can be prevented and reliability can be improved.

Example 5. In the abnormal state detection unit 13 of the second embodiment, the number of judgments made by the judgment number setting unit 1306 may be changed according to the plate thickness of the workpiece 2. FIG.
4 is a block diagram showing another example of the abnormal state detection unit 13 in the fifth embodiment of the present invention. In particular, in this embodiment, only the differences from the above embodiments will be described. In the figure, 1
Reference numeral 308 is a plate thickness determination circuit, and the NC controller 24 is used as an input.
From the latch output of the latch circuit 1406 of the energy control unit 14 is input to the input, and the output is the determination result setter that determines the result of determining the plate thickness. 1306, and the determination number setting device 1306 sets the determination number according to the plate thickness. Here, the machining volume per unit time is a value obtained by machining groove width x plate thickness x linear machining speed, and
The processing volume per unit time is proportional to the processing energy, the value peculiar to the material of the wire electrode 1 and the workpiece 2, and the like. Therefore, plate thickness = K × processing speed data / average energy value Eav
(K is a constant), and the plate thickness of the workpiece 2 can be determined from the processing speed data and the average energy value Eav. As described above, in the short-circuit pulse ratio comparing means including the coincidence comparison circuit 1305 and the judgment number setting unit 1306 of this embodiment, the judgment number setting unit 1306 determines the judgment number according to the plate thickness output from the plate thickness judging circuit 1308. A predetermined short circuit pulse ratio to be set and compared with the calculation result of the short circuit pulse ratio calculation means is used as a function of the plate thickness of the workpiece 2, and this corresponds to the embodiment corresponding to the claims.

Generally, the discharge position is likely to concentrate in the lengthwise direction of the plate thickness in the thin plate region, and in the thick plate region, the effect of jetting the machining liquid to the machined portion is poor, so that the frequency of the short-circuited state is high. Becomes higher. On the contrary, in the thin plate region, the effect of jetting the working liquid to the working portion is good, and in the thick plate region, the discharge positions are easily dispersed in the length direction of the plate thickness.
Therefore, even if the number of judgments is set uniformly, the processing speed is inevitably reduced due to the plate thickness. However, in the fifth embodiment, since the optimum detection corresponding to the plate thickness of the workpiece 2 can be performed, the processing speed is reduced. The decrease can be prevented.

Example 6. In the second embodiment, the output of the discharge pulse detection unit 12 to the abnormal state detection unit 13 is the short circuit pulse and the total machining pulse, but similarly, the normal discharge pulse and the total machining pulse may be output. . FIG. 15 is a block diagram showing another example of the abnormal state detection circuit 13 in the sixth embodiment of the present invention. In the figure, 12 is a discharge pulse detector, 1205 is a 3-input AND circuit, and the input is the main switching element 1 of the pulse control circuit 8.
The pulse signal S2 for driving 106, the on-time switching pulse signal S3 of the main switching element 1106, and the output of the comparison circuit 1201 are connected, and the output is the abnormal state detection unit 1
The pulse signal S2 that is connected to the input of the counter [A] 1031 of 3 and drives the main switching element 1106 of the pulse control circuit 8 is the counter [B] 1 of the abnormal state detection unit 13.
It is connected to the input of 032.

FIG. 16 is an explanatory diagram for explaining the operation of the discharge pulse detector 12. As shown in the figure, the normal discharge pulse and the pulse signal S2 are input to the abnormal state detection unit 13 at the timing of the pulse signal S2 that drives the main switching element 1106, and the counter [A] 1301 operates as a down counter. By doing so, the abnormality detection signal can be obtained as the ratio of the normal discharge pulse to the total machining pulse. The abnormal state detection means including the abnormal state detection circuit 13 of this embodiment is composed of the wire electrode 1 and the workpiece 2.
A total machining pulse counting means for applying a pulse voltage between them and counting the number of pulses per fixed time, and a no-load time from the application of the pulse voltage between the wire electrode 1 and the workpiece 2 until discharge occurs. Can be used as discharge pulse counting means for counting the discharge pulses generated in the workpiece 2 and the wire electrode 1 by means of the normal discharge pulse counting means for counting the number of pulses per fixed time longer than the predetermined time. Corresponds to an embodiment corresponding to the claims. Therefore,
The same effect as the second embodiment can be expected.

[0056]

As described above, the power supply control device for a wire electric discharge machine according to claim 1 detects the short-circuit pulse ratio or the normal electric discharge pulse ratio to detect an unstable portion such as a step on the workpiece. The change in the plate thickness can be accurately detected, and based on the result, it can be controlled so as not to exceed the limit energy level according to the processing state, and it is possible to always perform processing at the limit energy level. Therefore, it is possible to accurately prevent the occurrence of wire breakage due to an increase in processing energy in an abnormal state where many short-circuit states occur. Therefore, the reliability of wire breakage prevention can be improved, and the processing speed can be further improved.

By detecting the short-circuit pulse ratio, the power supply control device for the wire electric discharge machine according to claim 2 can accurately detect an unstable portion such as a step of the workpiece or a change in the plate thickness. Based on the above, it is possible to control so as not to exceed the limit energy level according to the processing state, and it is possible to always perform processing at the limit energy level. Therefore, when the plate thickness of the work piece changes abruptly or the wire breakage at the corners is likely to occur, the increase in the ratio of the short-circuit pulse obtained from the short-circuit detection means is used as the abnormality detection signal, and immediately before the abnormal state. It is possible to control the machining energy value so as not to exceed the average energy value of, and it is possible to reliably prevent wire breakage when the discharge frequency increases with an increase in the short-circuit pulse, that is, when the machining energy increases. Therefore, the reliability of wire breakage prevention can be improved, and the processing speed can be further improved.

According to a third aspect of the present invention, there is provided a power source control device for a wire electric discharge machine, wherein the abnormal state detecting means according to the second aspect includes discharge pulse counting means for counting the discharge pulses generated in the workpiece and the wire electrode. By a short circuit pulse ratio calculating means for calculating the ratio of short circuit pulses from the discharge pulse counting means and the short circuit detecting means, and a short circuit pulse ratio comparing means for comparing the calculation result of the short circuit pulse ratio calculating means with a predetermined short circuit pulse ratio. In addition to the effect of claim 2, the discharge pulse counting means for counting the discharge pulses, the short circuit pulse ratio calculating means, and the short circuit pulse ratio comparing means
Since it counts pulses, an abnormal state can be detected with high sensitivity.

According to a fourth aspect of the present invention, there is provided a power source control device for a wire electric discharge machine, wherein the discharge pulse counting means in the abnormal state detecting means according to the third aspect applies a pulse voltage between the wire electrode and the workpiece. Total machining pulse counting means for counting the number of pulses per fixed time, and a constant no-load time from the application of the pulse voltage between the wire electrode and the workpiece to the occurrence of discharge for a predetermined time or longer Since the normal discharge pulse counting means for counting the number of pulses per time is used, in addition to the effects of claim 2 and claim 3, the discharge pulse counting means, the total machining pulse counting means, and the normal discharge pulse counting means are: Since it counts pulses, an abnormal state can be detected with high sensitivity.

The abnormal state detecting means of the power supply control device for the wire electric discharge machine according to claim 5 is a no-load time detecting means for detecting a no-load time from the application of the pulse voltage to the occurrence of electric discharge; A normal discharge pulse counting means that counts pulses whose no-load time detected by the no-load time detecting means is longer than a predetermined no-load time compared to a predetermined time, and a short circuit from the normal discharge pulse counting means and the short-circuit detecting means. Since the abnormal state is determined by the short circuit pulse ratio calculating means for calculating the pulse ratio and the short circuit pulse ratio comparing means for comparing the calculation result of the short circuit pulse ratio calculating means with a predetermined short circuit pulse ratio, In addition to the effect of 2, in machining including a step such that the plate thickness of the workpiece becomes thin, the number of short-circuit pulses increases and the normal discharge pulse decreases at the step of the workpiece. An abnormal state by calculating the ratio of normal discharge pulses of fault pulses can be detected more sensitively.

The abnormal state detecting means of the power supply control device for the wire electric discharge machine according to claim 6 is smaller than the first short circuit pulse ratio comparing means and the predetermined pulse ratio of the first short circuit pulse ratio comparing means. A second short circuit pulse ratio comparison means for comparing with a predetermined pulse ratio and an abnormal state are discriminated by the first short circuit pulse ratio comparison means, and then the second short circuit pulse ratio comparison means releases the abnormal state. Therefore,
In addition to the effects of claim 2 to claim 5, when the processing becomes unstable at a location where the processing state changes rapidly such as a step of the workpiece, it becomes possible to perform processing within a predetermined hysteresis region. In addition, the reliability of wire breakage prevention can be improved, and the processing speed can be further improved.

The short-circuit pulse ratio comparing means of the power supply control device for the wire electric discharge machine according to the seventh aspect of the present invention determines a predetermined short-circuit pulse ratio to be compared with the calculation result of the short-circuit pulse ratio calculating means to determine the plate thickness of the workpiece. Claim 2 because it is a function
In addition to the effect of claim 5, since the predetermined short circuit pulse ratio to be compared with the calculation result of the short circuit pulse ratio calculation means is a function of the plate thickness of the workpiece, it corresponds to the plate thickness of the workpiece. Optimal detection can be performed and a reduction in processing speed can be prevented.

The machining energy control means of the power supply control device for the wire electric discharge machine according to claim 8 adds the energy values of the discharge pulses within the predetermined time, and calculates the average energy within the predetermined time from the addition result. During the period when the average energy calculating means and the abnormal state detecting means discriminate the abnormality, the addition result of the energy values of the discharge pulses exceeds the threshold value based on the arithmetic result of the average energy calculating means immediately before the abnormality is discriminated. Since the supply of the pulse voltage is controlled so that it does not occur, in addition to the effects of claims 2 to 7, for example, a limit current value such that the end face of the workpiece, the corner portion, or the plate thickness changes Even if the value decreases, the limit current value can be changed and controlled according to these situations, wire breakage can be reliably prevented, and the processing speed can be improved. In particular, it is possible to deal with a plate whose thickness gradually changes to a plurality.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a basic operation of a power supply control device for a wire electric discharge machine according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a wire electric discharge machine for explaining a power supply control device of the wire electric discharge machine according to the second embodiment of the present invention.

FIG. 3 is a connection diagram relating to a pulse control circuit for explaining a power supply control device for a wire electric discharge machine according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing details of a discharge pulse detection unit and an abnormal state detection unit in a power supply control device for a wire electric discharge machine according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing details of an energy control unit in the power supply control device of the wire electric discharge machine according to the second embodiment of the present invention.

FIG. 6 is a timing chart illustrating the operation of the pulse control circuit and the discharge pulse detection unit of FIGS. 1 and 2.

FIG. 7 is a timing chart showing the operation of the abnormal state detection unit in the power supply control device for the wire electric discharge machine according to the second embodiment of the present invention.

FIG. 8 is a timing chart showing the operation of the energy control unit in the power supply control device for the wire electric discharge machine according to the second embodiment of the present invention.

FIG. 9 is a block diagram showing another example of the abnormal state detection circuit in the power supply control device for the wire electric discharge machine according to the third embodiment of the present invention.

FIG. 10 is an explanatory diagram for explaining the operation of the discharge pulse detection unit in the power supply control device for the wire electric discharge machine according to the third embodiment of the present invention.

FIG. 11 is a short-circuit pulse / normal discharge pulse-time characteristic diagram in the power supply control device of the wire electric discharge machine according to the third embodiment of the present invention.

FIG. 12 is a block diagram illustrating another example of the abnormal state detection unit in the power supply control device of the wire electric discharge machine according to the third embodiment of the present invention.

FIG. 13 is a timing chart for explaining the operation of the abnormal state detection unit in the power supply control device for the wire electric discharge machine according to the fourth embodiment of the present invention.

FIG. 14 is a block diagram showing another example of the abnormal state detection unit in the power supply control device for the wire electric discharge machine according to the fifth embodiment of the present invention.

FIG. 15 is a block diagram showing another example of the abnormal state detection circuit in the power supply control device of the wire electric discharge machine according to the sixth embodiment of the present invention.

FIG. 16 is an explanatory diagram illustrating a discharge pulse detection unit in a power supply control device for a wire electric discharge machine according to a sixth embodiment of the present invention.

FIG. 17 is a configuration diagram showing a schematic configuration of a conventional wire electric discharge machine.

FIG. 18 is a machining current waveform diagram for explaining the operation of the conventional wire electric discharge machine.

[Explanation of symbols]

1 wire electrode, 2 workpiece, 7 discharge start detection circuit, 8 pulse control circuit, 11 machining power supply, 12 discharge pulse detection unit, 13 abnormal state detection unit, 14 energy control unit, 23 average machining voltage detection unit, 24 NC controller.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihito Imai 1-1-1, Tsukaguchihonmachi, Amagasaki-shi, Hyogo Sanryo Electric Co., Ltd. Industrial Systems Research Institute (72) Tatsushi Sato Hachimachi, Tsukaguchimoto, Amagasaki-shi, Hyogo 1-1-1 Sanryo Electric Co., Ltd. Industrial Systems Research Center

Claims (8)

[Claims] 1. A power supply control device for a wire electric discharge machine, wherein a pulse voltage is applied between a work piece and a wire electrode arranged opposite to the work piece to perform electric discharge machining. The ratio of the short-circuit pulse to the total machining pulse per constant time of the short-circuit pulse conducted in the state where no discharge is generated between the workpieces or from the application of the pulse voltage between the wire electrode and the workpiece until the discharge is generated. A power supply control device for a wire electric discharge machine, characterized in that a machining energy value is changed according to a ratio of a normal electric discharge pulse to a total machining pulse per constant time of a pulse having a no-load time longer than a predetermined time. 2. A power supply control device for a wire electric discharge machine, wherein a pulse voltage is applied between a work piece and a wire electrode arranged to face the work piece to perform electric discharge machining. Short circuit detection means for detecting that the wire electrode is in a short circuit state, an abnormal state detection means for discriminating an abnormal state by the detection result of the short circuit detection means, and a period discriminated as abnormal by the abnormal state detection means,
And a machining energy control means for adding the energy values of the discharge pulses within a predetermined time and stopping the supply of the pulse voltage so that the addition result does not exceed the predetermined energy value. Power control device for processing machines. 3. The abnormal condition detecting means includes a discharge pulse counting means for counting the discharge pulses generated in the workpiece and the wire electrode, and a ratio of short-circuit pulses from the discharge pulse counting means and the short-circuit detecting means. 3. The wire discharge according to claim 2, further comprising: a short circuit pulse ratio calculating unit for calculating a short circuit pulse ratio calculating unit and a short circuit pulse ratio comparing unit for comparing a calculation result of the short circuit pulse ratio calculating unit with a predetermined short circuit pulse ratio. Power control device for processing machines. 4. The discharge pulse counting means for counting the discharge pulses generated in the workpiece and the wire electrode of the abnormal state detecting means applies a pulse voltage between the wire electrode and the workpiece, and Total machining pulse counting means for counting the number of pulses per fixed time, and a constant no-load time from the application of the pulse voltage between the wire electrode and the workpiece to the occurrence of discharge for a predetermined time or longer The power supply control device for a wire electric discharge machine according to claim 3, further comprising a normal discharge pulse counting means for counting the number of pulses per time. 5. The no-load time detecting means for detecting the no-load time from application of the pulse voltage to the occurrence of discharge, and the no-load time detecting means for detecting the no-load time. Short-circuit pulse ratio calculation for calculating the ratio of short-circuit pulses from the normal discharge pulse counting means for counting the pulses whose time is longer than the predetermined no-load time as compared with the predetermined time, and the normal discharge pulse counting means and the short-circuit detecting means. The power supply control device for a wire electric discharge machine according to claim 2, further comprising: means and a short circuit pulse ratio comparison means for comparing a calculation result of the short circuit pulse ratio calculation means with a predetermined short circuit pulse ratio. 6. The abnormal state detecting means compares a first short circuit pulse ratio comparing means with a second short circuit comparing a predetermined pulse ratio smaller than the predetermined pulse ratio of the first short circuit pulse ratio comparing means. 6. The abnormal state is canceled by the second short circuit pulse ratio comparison means after the abnormal state is discriminated by the pulse ratio comparison means and the first short circuit pulse ratio comparison means. A power supply control device for a wire electric discharge machine according to any one of 1. 7. The short circuit pulse ratio comparison means uses a predetermined short circuit pulse ratio to be compared with the calculation result of the short circuit pulse ratio calculation means as a function of the plate thickness of the workpiece. A power supply control device for a wire electric discharge machine according to claim 5. 8. The processing energy control means adds an energy value of the discharge pulse within the predetermined time, and calculates an average energy within a predetermined time from the addition result, and the abnormal state detection means. During the period when it is determined to be abnormal, the supply of the pulse voltage is controlled so that the addition result of the energy values of the discharge pulses does not exceed the threshold value based on the calculation result of the average energy calculation means immediately before it is determined to be abnormal. The power supply control device for the wire electric discharge machine according to any one of claims 2 to 7.