JPH08257839A - Electric discharge machining device - Google Patents

Abstract

PURPOSE: To smoothly perform a transfer of electric discharge by a plurality of power supplies so as to prevent decreasing a machining speed, by providing a discharge stop release means of releasing discharge stopping of the power supply of a discharge stop means based on detecting voltage between electrodes. CONSTITUTION: Since a discharge is generated after a voltage between electrode exceeds a discharge detection level by once applying a DC power supply, after generating the discharge, instantaneously outputs 8401, 802 are made to '1', to well transfer a discharge by applying the other DC power supply between electrodes without interrupting the discharge. In the case of rapidly narrowing an interelectrode clearance, even when applied the DC power supply between electrodes, a long time is taken for the interelectrode voltage to exceed a discharge detection level. However, due to a long time Tdead, after the time Tdead from applying the DC power supply between electrodes, already a monitor voltage output 701 is changed to '1'. Consequently, applying the other DC power supply between the electrodes is prevented, by misdetecting that the discharge is induced.

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.

[0002]

2. Description of the Related Art FIGS. 5, 6, 7, and 8 show an example of a conventional electric discharge machine.

In FIG. 5, 1 is a machining electrode, 2 is a work piece, 3 is a first direct current power source with variable voltage, 4 is a second direct current power source, and 5 is a first direct current power source for controlling opening and closing of the direct current power source 3. A switching element, 6 is a second switching element that controls the opening and closing of the DC power supply 4, 7 is a voltage monitor circuit that determines the presence or absence of discharge between the electrodes, 8 is a switching circuit that controls the opening and closing of the switching elements 5 and 6, and 9 , 10 are insulating circuits that insulate the switching elements 5 and 6 from the switching circuit 8 and do not have the function of converting the logical value of a signal. Reference numeral 11 is a current limiting resistor for limiting the current supplied from the DC power supply 3, V1
Is the voltage value of the DC power supply 3, V2 is the voltage value of the DC power supply 4, E
Reference numeral 2 is a voltage value between electrodes, 7i1 and 7i2 are input signals to the voltage monitor circuit 7, 7o1 is an output signal from the voltage monitor circuit 7, and 8o1 and 8o2 are output signals from the switching circuit 8.

FIG. 6 shows the switching circuit 8 in FIG.
It is a figure showing the details of. In the figure, 81, 82, 8
Reference numeral 3 is a one-shot circuit (which outputs a pulse having a fixed width to the trigger input), and the output is "0" or "1" for a fixed time after the trigger input becomes "1". 8
Reference numeral 4 is a logic gate, and 83o1 is an output of the one-shot circuit 83. The 83o1 output becomes "1" for a fixed time Tdead after 8o1 becomes "1". 84o1
The output becomes "1" only when both 83o1 and 7o1 are "0". The 8o1 output becomes "0" for a certain time Toff after 84o1 becomes "1". The 8o2 output becomes "1" for a certain time Ton after 84o1 becomes "1".

FIG. 7 is a diagram showing details of the voltage monitor circuit in FIG. In the figure, 71 is a comparator, and 72 and 73 are voltage dividing resistors. 74 is a DC power supply having a voltage value E0. The voltage between contacts is divided by the resistors 72 and 73, and the resistance values of the resistors 72 and 73 are set to R72 and R7.
When it is set to 3, the voltage between contacts is E0 ・ R73 / (R72 + R7
If it is larger than 3), the output signal 7o1 is "1", and if it is smaller than a certain fixed value, the output signal 7o1 is "0".

FIG. 8 is a waveform chart explaining the operation in FIG.

Next, the operation will be described. The voltage monitor circuit 7 is configured to determine and output a change in an electrical state when an electric discharge occurs in the machining gap between the machining electrode 1 and the workpiece 2 based on the voltage appearing between the electrodes. And has a reference voltage E1 for comparing its input voltage E2, where E1 = E0. (R72 + R73) / R7
It is 3. When E1 <E2, the output 7o1 emits "1". When E2 <E1, the output 7o1 becomes "0". The reference voltage E1 is the voltage dividing resistors 72, 7 in FIG.
It is determined by the combination of three. The switching circuit 8 has two outputs 8o1 and 8o2.

Next, description will be made with reference to the waveform chart shown in FIG. In FIG. 8, the voltage waveform between the poles is shown at the top. First, the output 8 of the switching circuit 8
O1 becomes "1", the switching element 5 is turned on, and a DC pulse voltage of V1 is applied to the machining gap. 8
After the output of o1 becomes "1" and a certain delay time Tdead elapses, the output 7o1 of the voltage monitor circuit 7 sets the switching element 6 to either the open state or the closed state. That is, after the delay time Tdead elapses, discharge is generated between the electrodes and the voltage between the electrodes becomes E2 <E1, or the delay time Tde
If discharge has already occurred and the voltage between contacts has already become E2 <E1 when dead has passed, the 8o2 output becomes "1", the switching element 6 becomes conductive, and the second DC power supply 4
Discharges only during Ton due to its high peak current capacity. After that, the output of 8o1 becomes "0" during Toff. The above operation is repeated. At this time, most of the processing amount is performed by the current supplied from the second DC power supply 4. On the other hand, when machining is performed only by the second DC power source, since the voltage value is large, the discharge is generated even if the distance between the electrodes is large, so that the discharge gap is varied, the machining accuracy is lowered, and further, when the voltage is applied. Since there is a large difference between the inter-electrode voltage values when there is no discharge and when an electric discharge occurs, machining becomes unstable when servo control is performed to control the inter-electrode distance based on the average voltage value between the electrodes. Most electric discharge machines have the above-mentioned dual power supply type power supply form.

Next, the reason why it is necessary to prohibit the output of 8o2 from becoming "1" during Tdead will be described. FIG. 9 shows an example when Tdead is extremely shortened. 83o1 becomes “0” before the switching element 5 is turned on and the voltage between contacts does not reach E1, that is, before 7o1 does not become “1”, so 83o1 becomes “0” and at the same time 84o1 becomes “1”. "And then 8o2
Also becomes "1", and the switching element 6 is turned on even if the discharge is not generated. Therefore, even if the discharge does not occur, it takes a short time even if the discharge occurs, and the machining speed decreases. In an electric discharge machine with a servo function that controls the voltage between contacts to a certain level,
The machining gap becomes unstable due to the drastic change in the voltage between contacts.

FIG. 10 shows an example in which Tdead is made extremely long. After the DC power supply 3 was applied between the electrodes and the voltage between the electrodes exceeded the discharge detection level E1, the discharge was induced relatively early. However, since Tdead is long, 83o1 is still "1" at the time of the discharge, so immediately 84o1. , 8o2 did not become "1", and the DC power supply 4 was applied between the electrodes after the discharge was interrupted, so that the discharge was not successfully transferred, and the high peak current by the second DC power supply 4 is shown. Is not supplied to the gap, which reduces the processing speed. DC power supply 3
When a voltage is applied to the gap between the electrodes, if a gap between the gaps has already occurred due to machining scraps, etc., a large current due to a short circuit during Tdead flows between the gaps. It will damage the work piece.

That is, the Tdead is required to have an appropriate length according to the condition of the gap.

FIG. 11 shows the voltage value V1 and the voltage monitor circuit 7.
It shows the relationship of the output of. As shown in this figure, the time required for the voltage between the electrodes to become larger than E1 after the voltage from the DC power supply 3 is started to be supplied to the electrodes, that is, for the output 7o1 of the voltage monitor 7 to become "1". It can be seen that the longer time becomes longer as the voltage value V1 becomes smaller. That is, as the voltage value V1 decreases, Tdea
The value of d needs to be longer.

FIG. 12 shows an example in which capacitors are connected in parallel between the electrodes in order to improve the sustainability of the discharge induced by the DC power supply 3. In the figure, 12, 13
Is a capacitor, and 14 and 15 are capacitors 12 between the electrodes,
13 is a switch for controlling the connection. In the case of such a device, the larger the capacity of the capacitor connected between the poles is, the slower the rise of the voltage of the DC power supply 3 becomes.
A longer dead value is required. FIG.
FIG. 12 is a diagram showing how the monitor output changes between the poles when the voltage value of the DC power supply 3 is the same. When the capacitance of the capacitor becomes larger than that in the figure, the rise of the voltage between the poles becomes dull and the voltage between the poles becomes E1. It can be seen that it takes longer to get larger.

Similarly, also in an electric discharge machine equipped with a servo mechanism for controlling the inter-electrode distance according to the settable inter-electrode average voltage value, if the inter-electrode set average voltage is low and the inter-electrode distance is small. , The capacitor component between the poles becomes large, so that the value of Tdead needs to be longer. 14
Is an example of an electric discharge machine equipped with a servo mechanism for controlling the distance between the electrodes according to the average voltage value between the electrodes. In the figure, 1
00 is a machining power source, 101 is an inter-electrode voltage detection circuit that detects an average voltage between the electrodes, 102 is a servo circuit that performs servo using the inter-electrode voltage, 103 and 104 are motors controlled by the servo circuit 102, and 105 is It is a cross table on which the workpiece 2 is placed and which is driven by motors 103 and 104. In an electric discharge machine equipped with such a servo mechanism, control is performed to make the inter-electrode voltage constant. In general, the inter-electrode voltage decreases as the inter-electrode distance increases, and conversely, the inter-electrode voltage increases as the inter-electrode distance decreases. Therefore, the servo circuit 102 causes the motors 104, 104 to increase the inter-electrode distance by decreasing the inter-electrode distance, and conversely, increase the inter-electrode distance by decreasing the inter-electrode voltage.
105 and the cross table 105 are driven.

Next, FIG. 15 shows the relationship between the voltage value V1 and the inter-electrode voltage when the discharge induced by the DC power supply 3 occurs. From this figure, it can be seen that as the voltage value V1 increases, the inter-electrode voltage at the time of occurrence of discharge induced by the DC power supply 3 increases. Therefore, the voltage value V
When 1 is increased, it is necessary to increase E1 which is the detection level of discharge occurrence.

Therefore, the voltage value of the DC power source on the side of inducing the discharge, the capacitance value of the capacitor inserted between the electrodes to improve the sustainability of the discharge induced by the DC power source, and the average voltage value between the electrodes In response to changes in the set average voltage value of the servo mechanism that controls the inter-electrode distance, Tdead
9 and FIG. 10 can be solved by changing the length of E.sub.1 and the value of E1 which is the detection level of discharge occurrence.

[0017]

FIG. 16 shows that in the conventional apparatus, when the gap between the electrodes suddenly widens during processing, the distance between the electrodes is large, so that the capacitor component between the electrodes is small and the DC power supply 3 is When the voltage applied between the electrodes exceeds the discharge detection level E1 in a short time and then the discharge is induced relatively early, or when the gap between the electrodes suddenly narrows during machining, Is small, the inter-electrode capacitor component is large, and it takes a long time for the inter-electrode voltage to exceed the discharge detection level E1 even when the DC power supply 3 is applied between the electrodes.
When the gap between the electrodes suddenly widens, the DC power supply 3 is applied between the electrodes, the voltage between the electrodes exceeds the discharge detection level E1 in a short time, and the discharge is induced relatively early, but the Tdead is long and the discharge occurs. Since the output of 83o1 is still "1", 8o2 and 84o1 do not immediately become "1", and the DC power supply 4 is applied between the electrodes after the discharge is interrupted. Therefore, the discharge is not successfully transferred. When the gap between the electrodes suddenly narrows, it takes a long time for the voltage between the electrodes to exceed the discharge detection level E1 even if the DC power supply 3 is applied between the electrodes. Since the voltage monitor output 7o1 remains "0" even after the time Tdead has elapsed since the start of
Although the discharge is erroneously detected and the discharge is not induced, the DC power supply 4 is applied between the electrodes.

As described above, since the conventional electric discharge machine of the electric discharge machine is constructed as described above, for example, when the distance between the electrodes is changed abruptly, the switching of a plurality of power supplies is delayed, so that the electric discharge is transferred. However, there was a problem that the processing was not performed smoothly and the processing speed decreased.

The present invention has been made in order to solve the above-mentioned problems, and the electric discharge machining apparatus of the electric discharge machining apparatus in which the electric discharge is smoothly transferred by a plurality of power sources and the machining speed does not decrease. The purpose is to get.

[0020]

According to a first aspect of the present invention, there is provided an electric discharge machine, a plurality of power sources for generating discharge energy, a detecting means for detecting a voltage between electrodes, and a first power source during discharging. A discharge stopping means for stopping the discharge by the second power source for a predetermined time; and a discharge stop releasing means for canceling the discharge stop of the second power source of the discharge stopping means based on the voltage detection between the electrodes of the detecting means. Be prepared.
The electric discharge machine according to claim 2 of the present invention has a plurality of different power supplies that generate discharge energy, a detection unit that detects the voltage between the electrodes, and a discharge by the second power supply during discharge by the first power supply. Control for changing the discharge stop time of the second power supply of the discharge stop means in accordance with the voltage value of the first power supply based on the discharge stop means for stopping the discharge for a predetermined time and the voltage detection between the electrodes of the detection means. And means. Further, according to a third aspect of the present invention, there is provided an electric discharge machine, a plurality of power sources for generating electric discharge energy, a detecting means for detecting a voltage between electrodes, and a capacitor having a variable capacitance connected in parallel between the electrodes. , The discharge stop means for stopping the discharge by the second power supply for a predetermined time during the discharge by the first power supply, and the discharge stop of the second power supply by the discharge stop means based on the voltage detection between the electrodes of the detection means. And a control means for changing the operating time according to the capacitance of the capacitor. Further, an electric discharge machine according to a fourth aspect of the present invention is provided with a distance control means for controlling the inter-electrode distance according to a predetermined inter-electrode voltage value. Furthermore, an electric discharge machine according to a fifth aspect of the present invention comprises a level changing circuit for changing the electric discharge detection level of the detecting circuit.

[0021]

According to the electric discharge machining apparatus of the first aspect of the invention configured as described above, the discharge stop of the second power source of the discharge stop means is released based on the voltage detection between the electrodes of the detection means.
Further, in the electric discharge machining apparatus according to the invention of claim 2 configured as described above, based on the voltage detection between the electrodes of the detection means,
The discharge stopping time of the second power supply of the discharge stopping means is changed according to the voltage value of the first power supply. According to the electric discharge machining apparatus of the invention of claim 3 configured as described above, based on the voltage detection between the electrodes of the detection means, the discharge stop time of the second power source of the discharge stop means is set to the value of the capacitor. It changes according to the capacity. Further, the electric discharge machining apparatus according to the invention of claim 4 configured as described above controls the inter-electrode distance according to a predetermined inter-electrode voltage value. Furthermore, the electric discharge machining apparatus of the fifth aspect of the present invention configured as described above changes the electric discharge detection level of the detection circuit.

[0022]

【Example】

Example 1. After the first switching circuit on the side of inducing discharge is turned on, a circuit that prohibits the second switching circuit from turning on for a certain period of time, and the detection circuit detects that the voltage between contacts has reached a certain level. A description will be given of an electric discharge machining apparatus including a circuit that enables the second switching circuit to be turned on even within the time. An embodiment of the present invention will be described below with reference to FIG. A schematic view of an electric discharge machine that realizes the present invention is the same as FIG. 5, which is a schematic view of a conventional electric discharge machine. FIG. 1 shows the inside of the switching circuit 8 in FIG. In FIG. 1, the same reference numerals as those in FIG. 6 showing the conventional example indicate the same or corresponding portions.

FIG. 1 is almost the same as FIG. 6 showing the conventional example.
In this embodiment, a flip-flop 85 and logic gates 86 and 87 are added to the conventional example.

Next, the operation will be described with reference to FIG. 1 and FIG. 2 which is a waveform chart relating to the present invention. In the present invention, the output 8o1 of the switching circuit 8 becomes "1", the voltage application between the electrodes by the DC power supply 3 is started, and when the voltage between the electrodes becomes higher than the discharge detection level E1, the output 7o1 of the voltage monitor circuit becomes "1". 1 ”. Therefore, the exit of the logic gate 87 which is the logical product of the input 8o1 and the input 7o1 becomes "1" at this time. Therefore, the output 85o1 of the flip-flop circuit 85 becomes "1" only when the voltage between the electrodes is smaller than the discharge detection level E1 after the voltage application between the electrodes by the DC power supply 3 is started. The output 86o1 of the logic gate 86 is a logical sum of the output 83o1 of "1" during the Tdead period after the voltage application between the poles by the DC power supply 3 is started and the output 85o1 of the flip-flop circuit 85. The output 86o1 of the logic gate 86 can be increased as long as the voltage between the electrodes is once higher than the discharge detection level E1 after the voltage application between the electrodes by the power supply 3 is started.
Becomes "0". The logic gate 84 is the logic gate 86.
Since the output 86o1 of the discharge monitor 7 and the output 7o1 of the discharge monitor 7 are the logical product, when the input 86o1 is "0", the input 7o1 is "0".
At the same time, the output 84o1 becomes "1". When the input 84o1 changes from "0" to "1", the one-shot circuit 82 outputs the Ton time "1" as the output 8o2. Therefore, after the voltage application between the electrodes by the DC power supply 3 is started, the voltage between the electrodes is once larger than the discharge detection level E1, and the output 86o1 of the logic gate 86 is "0".
After that, even if the time Tdead has not elapsed since the application of the voltage between the electrodes by the DC power supply 3 started, the discharge is induced between the electrodes and the output 7o1 of the discharge monitor circuit becomes “0”. "8", the output 8o2 of the one-shot circuit 82 becomes "1", and the voltage application between the electrodes by the DC power supply 4 is started. Therefore, in the electric discharge machine according to the present embodiment, the time Tdead can be set relatively long. FIG. 2 shows that when the gap between the electrodes suddenly expands during machining, the distance between the electrodes is large, so that the capacitor component between the electrodes is small and the voltage between the electrodes is discharged in a short time when the DC power supply 3 is applied between the electrodes. When the discharge is induced relatively early after exceeding the detection level E1 and when the gap between the electrodes suddenly narrows during machining, the distance between the electrodes is small, so the capacitor component between the electrodes is large and In this example, it takes a long time for the voltage between the electrodes to exceed the discharge detection level E1 even if the power source 3 is applied between the electrodes. When the gap between the electrodes suddenly widened, the DC power supply 3 was applied between the electrodes, the voltage between the electrodes exceeded the discharge detection level E1 in a short time, and the discharge was induced relatively early.
Although the dead is long and the 83o1 output is still "1" when the discharge occurs, the discharge is generated immediately after the voltage between the electrodes due to the application of the DC power supply 3 exceeds the discharge detection level E1, and therefore 84o1 and 8o2 are immediately generated. Is “1”, and the DC power supply 4 is applied between the electrodes without interruption of the discharge, so that the discharge is successfully transferred. When the gap between the electrodes suddenly narrows, it takes a long time for the voltage between the electrodes to exceed the discharge detection level E1 even if the DC power supply 3 is applied between the electrodes, but since Tdead is long, the DC voltage is long. Since the voltage monitor output 7o1 has already changed to "1" when the Tdead time has elapsed after the power source 3 is applied between the electrodes, it is erroneously detected that the discharge has been triggered, and the discharge is not triggered, The DC power supply 4 is not applied between the poles.

As described above, the voltage value of the DC power source on the side of inducing the discharge, the capacitance value of the capacitor inserted between the poles to improve the sustainability of the discharge induced by the DC power source, and the average voltage between the poles. If there is little change in the set average voltage value of the servo mechanism that controls the distance between the electrodes according to the value, the transition of the discharge is smooth and the machining is stable even in the situation between the electrodes due to a sudden change in the distance between the electrodes To be done efficiently.

Example 2. A circuit that prohibits the second switching circuit from turning on for a certain period of time after the first switching circuit on the discharge inducing side turns on, and the prohibiting time depends on the DC power supply voltage value of the first switching circuit. A circuit for changing the voltage and a circuit for enabling the second switching circuit to be turned on within the fixed time when the detection circuit detects that the voltage between the electrodes has reached a certain level. The electric discharge machining apparatus will be described. FIG. 3 shows an embodiment of the present invention. In the case of this embodiment, the diagram showing the overall outline is the same as FIG. 5 showing the conventional example,
The switching circuit 8 in FIG. 5 is the same as that in FIG.
The voltage monitor circuit 7 in FIG. 5 is also the same as FIG. 7 showing the conventional example. The switching circuit 8 in FIG. 5 is the same as that in FIG. 1 showing the first embodiment. In this embodiment, the one-shot circuit 83 shown in FIG. 1 is improved, and its details are shown in FIG. 3, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions. 831
In the shift register, when the 8o1 signal is "1", the shift operation is performed and the plurality of output pins are connected to the data selector 832. A data bus corresponding to the DC power supply voltage value V1 of the first switching circuit is simultaneously connected to the data selector 832, and one of the input pins from the shift register is selected and selected corresponding to the data of V1. The signal appearing on the other pin is output and sent to the logic gate 834. Reference numerals 835 and 836 are logic gates. Therefore, the 83o1 output becomes a one-shot output which becomes "1" at the same time when 8o1 becomes "1" and becomes "0" at the same time when the signal selected by the data selector 832 becomes "1".

Next, the operation will be described. In the present embodiment, when the voltage value V1 of the DC power supply 3 becomes large, the output becomes “1” within a short time after the voltage application between the electrodes by the DC power supply 3 among the plurality of output pins of the shift register 71 is started. The output pin that becomes "" is selected by the data selector of 78 and then output to the logic gate 834. On the contrary, when the voltage value V1 of the DC power supply 3 becomes small, the output becomes “1” for a long time after the application of the voltage between the electrodes by the DC power supply 3 among the plurality of output pins of the shift register 71 is started. Output pin is selected by the data selector of 78 and then output to the logic gate 834. Therefore, if the voltage value V1 of the DC power supply 3 decreases and the time required for the DC power supply 3 to be applied between the electrodes and for the voltage between the electrodes to exceed the discharge detection level E1 increases, the time Tdead increases and the DC power supply 3 If the voltage value V1 of the above becomes large and the time required for the DC power supply 3 to be applied between the electrodes and the voltage between the electrodes to exceed the discharge detection level E1 becomes short, the time Tdead becomes short.

As described above, even if the voltage value of the DC power source on the side of inducing the discharge changes or the distance between the electrodes changes suddenly, the transfer of the discharge is smooth and the machining is stable and efficient. Be seen. Further, when a detection circuit detects that the voltage between contacts has reached a certain level, a circuit that enables the second switching circuit to be turned on within the fixed time is provided, thereby inducing discharge. Since the control of the time Tdead with respect to the change of the voltage value of the DC power source on the side of performing the operation can be performed relatively roughly, the apparatus becomes inexpensive.

Example 3. A capacitor circuit having a variable capacitance connected between the poles and a circuit for inhibiting the second switching circuit from being turned on for a certain period of time after the first switching circuit on the discharge inducing side is turned on, and the circuit for inhibiting the same. A circuit that changes the time depending on the capacitance of the capacitor circuit, and a detection circuit that detects that the voltage between contacts has reached a certain level enables the second switching circuit to be turned on even within the fixed time. An electric discharge machine including a circuit having the following will be described. As described above in the section of the conventional example, in an electric discharge machine equipped with a capacitor circuit having a variable capacity connected between the electrodes,
For example, when the capacitance of the capacitor circuit is large, the time required for the voltage between the electrodes to become higher than the discharge detection level E1 after the voltage application between the electrodes by the DC power supply 3 is started becomes longer as an example. Therefore, the circuits similar to those of FIGS. 1, 3 and 4 used in the above-described embodiment are used in the circuit of FIG. 12, and data corresponding to the capacitance of the capacitor circuit is provided in the V1 data bus portion of FIG. If the capacitance of the capacitor circuit is reduced by outputting the voltage, the output selector 832 selects the output pin whose output becomes “1” in a short time after the voltage application between the electrodes by the DC power supply 3 is started. If the capacity of the capacitor becomes large, the output pin whose output becomes “1” for a long time after the voltage application between the electrodes by the DC power supply 3 is started is selected by the data selector 832, and the capacitor circuit is The capacity of
If the time required for the DC power supply 3 to be applied between the electrodes and the voltage between the electrodes to exceed the discharge detection level E1 becomes long, the time Tde
ad becomes longer, the capacity of the capacitor circuit increases,
If the time required for the DC power supply 3 to be applied between the electrodes and the voltage between the electrodes to exceed the discharge detection level E1 becomes short, the time Tde
ad becomes short.

As described above, even if the capacitance of the capacitor connected between the electrodes changes or the distance between the electrodes changes abruptly, the transition of the discharge is smooth and the machining is stably and efficiently performed. Further, when the detection circuit detects that the voltage between the electrodes has reached a certain level, the circuit that enables the second switching circuit to be turned on within the fixed time is provided with Since the control of the time Tdead with respect to the change in the capacity of the connected capacitor can be performed relatively roughly, the device becomes inexpensive.

Example 4. A servo mechanism for controlling the inter-electrode distance according to a settable average voltage value between the poles, and a circuit for inhibiting the second switching circuit from being turned on for a certain period of time after the first switching circuit for inducing discharge is turned on. A circuit for changing the prohibition time according to the settable average voltage value between the electrodes, and a detection circuit for detecting that the voltage between the electrodes has reached a certain level, even if it is within the predetermined time, An electric discharge machining apparatus comprising a circuit that enables the switching circuit 2 to be turned on will be described. As described in the section of the conventional example, the servo for controlling the inter-electrode distance according to the settable average voltage value between the electrodes, as in the electric discharge machine, which includes the capacitor circuit having a variable capacity connected between the electrodes. In an electric discharge machine equipped with a mechanism, as shown in FIG. 5, when the set average voltage between the electrodes is low and the distance between the electrodes is small, the capacitor component between the electrodes is large. The time required for the inter-electrode voltage to become higher than the discharge detection level E1 after the application of the voltage to the circuit is started becomes longer. Therefore, a circuit similar to that shown in FIGS. 1 and 3 used in the above-described embodiment is included, and V of FIG.
Data corresponding to the set inter-electrode average voltage value is output to one data bus portion, and if the set inter-electrode average voltage value becomes small,
If the output pin whose output becomes “1” within a short time after the DC power supply 3 starts applying the voltage between the electrodes is selected by the data selector 832 and the set inter-electrode average voltage value becomes large, the DC power supply 3 If the data selector of 832 selects the output pin whose output becomes “1” for a long time after the voltage application to the inter-electrode is started by the 3 is applied between the electrodes and the time required for the voltage between electrodes to exceed the discharge detection level E1 becomes longer, the time Tdead becomes longer, the set average voltage value between electrodes becomes larger, and the DC power supply 3 is applied between the electrodes. If the time required for the voltage between contacts to exceed the discharge detection level E1 becomes shorter, the time Tdead becomes shorter.

As described above, even if the set average voltage value of the servo mechanism for controlling the inter-electrode distance changes in accordance with the set inter-electrode average voltage value or the inter-electrode distance changes suddenly, the electric discharge is generated. The transition is smooth and the processing is stable and efficient.
Further, when the detection circuit detects that the voltage between contacts has reached a certain level, the second switching circuit can be turned on even within the fixed time, thereby providing the set average voltage. Time Tdea for change in value
Since the control of d can be performed relatively roughly, the device becomes inexpensive.

Example 5. After the first switching circuit for inducing discharge is turned on, the second switching circuit is turned off.
The circuit for prohibiting N from turning on for a certain time, the circuit for changing the detection level of the discharge detection circuit according to the DC power supply voltage value of the first switching circuit, and the voltage between contacts reached a certain level by the detection circuit. A circuit for enabling the second switching circuit to be turned on even within the fixed time when the above is detected will be described. FIG. 4 is a diagram of a voltage monitor circuit for implementing this embodiment, which is an improvement of the voltage monitor circuit 7 of FIG. 5 showing a conventional example. The schematic diagram of the power supply device is the same as FIG. 5 showing a conventional example. The switching circuit in FIG. 5 is the same as that in FIG. In FIG. 4, 71 is a comparator, 77, 78, 79 are relays, 771, 78.
1, 791 are contacts of relays 77, 78, 79,
761, 762, and 763 are relays 7 which are based on the DC power supply voltage value V1 of the switching circuit that induces discharge.
A relay driver for controlling the opening / closing of 7, 78, 79 drives a relay that requires a large amount of current with a small amount of current. 72,741,742,743,75
Is a voltage dividing resistor for dividing the voltage between electrodes.

Next, the operation will be described. Although the conventional example has been described with reference to FIGS. 11 and 15, assuming that the discharge detection level E1 is fixed, when the power supply voltage value V1 on the discharge inducing side increases, the discharge generation induced by the DC power supply 3 occurs. However, if the time required for the voltage between contacts to exceed the discharge detection level E1 becomes shorter and the power supply voltage value V1 on the discharge inducing side becomes smaller, the discharge induced by the DC power supply 3 becomes larger. Although the inter-electrode voltage at the time of occurrence becomes smaller, the time required for the inter-electrode voltage to exceed the discharge detection level E1 becomes longer. Therefore, if the power supply voltage value V1 on the discharge inducing side is increased, the detection level E1 is increased and the power supply voltage value V1 on the discharge inducing side is increased.
Is smaller, it is not necessary to change the time Tdead significantly if the detection level E1 is reduced. Therefore, if the power supply voltage value V1 on the discharge inducing side is increased, the detection level E1 is increased, and if the power supply voltage value V1 on the discharge inducing side is decreased, the detection level E1 is decreased. If the relays 76, 77 and 78 are controlled, the control of the time Tdead can be rough or can be smoothly performed even if there is no control.

As described above, even if the voltage value of the DC power source on the side of inducing discharge changes or the distance between the electrodes changes suddenly, the discharge transition is smooth and machining is stable and efficient. Be seen. Further, when a detection circuit detects that the voltage between contacts has reached a certain level, a circuit that enables the second switching circuit to be turned on within the fixed time is provided, thereby inducing discharge. Since the control of the discharge detection level of the discharge detection circuit with respect to the change in the voltage value of the DC power source on the side of performing the discharge can be performed relatively roughly, the apparatus becomes inexpensive.

Although the embodiments have been described above individually, a better effect can be expected by combining these embodiments.

[0037]

As described above, according to the first aspect of the invention, the discharge stop of the second power supply of the discharge stop means is released based on the voltage detection result between the electrodes. The transition to the second power source becomes smooth, and machining can be performed stably and efficiently. Further, according to the invention of claim 2, based on the voltage detection result between the electrodes, the discharge stopping time of the second power supply of the discharge stopping means is changed according to the voltage value of the first current, whereby the first power supply is changed. From the second electric current to the second electric current becomes smooth, and the processing can be performed stably and efficiently. Further, according to the invention of claim 3, based on the result of the voltage detection between the electrodes, by changing the discharge stop time of the second power source of the discharge stop means according to the capacitance of the capacitor provided between the electrodes, The transition from the first power source to the second power source becomes smooth, and the processing can be performed stably and efficiently.

[Brief description of drawings]

FIG. 1 shows an embodiment of a switching circuit of an electric discharge machine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG.

FIG. 3 shows a modification of a part of the switching circuit in FIG.

FIG. 4 shows an embodiment of a voltage monitor circuit of an electric discharge machine according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of a power supply device for electric discharge machining of a conventional electric discharge machine.

FIG. 6 shows a modification of a part of the switching circuit configured by FIG.

7 shows an example of the voltage monitor circuit in FIG.

FIG. 8 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 5;

FIG. 9 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 5;

FIG. 10 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 5;

FIG. 11 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 5;

FIG. 12 is a schematic diagram of a power supply device for electric discharge machining of a conventional electric discharge machine.

FIG. 13 is a view showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 12;

FIG. 14 is a schematic view of a conventional electric discharge machine.

FIG. 15 is a diagram showing a machining gap condition and a power supply device state of the electric discharge machine configured by FIG. 5;

16 is a diagram showing a machining gap condition and a power supply device state during machining of the electric discharge machining apparatus configured by FIG. 5. FIG.

[Explanation of symbols]

1 processing electrode, 2 workpiece, 3 voltage variable DC power supply, 4 voltage variable DC power supply, 5 switching elements,
6 switching elements, 7 voltage monitors, 8 switching circuits.

Claims (5)

[Claims] 1. An electric discharge machining apparatus, wherein a conductive machining liquid is interposed between an electrode and a workpiece to generate an electric discharge, and machining is performed by the electric discharge energy, a plurality of power sources for generating the electric discharge energy, Based on the detection means for detecting the voltage between the electrodes, the discharge stopping means for stopping the discharge by the second power supply for a predetermined time during the discharge by the first power supply, and the voltage detection between the electrodes of the detection means. An electric discharge machine comprising: a discharge stop canceling means for canceling discharge stop of the second power source of the discharge stopping means. 2. An electric discharge machining apparatus, wherein a conductive machining fluid is interposed between an electrode and a workpiece to generate an electric discharge, and machining is performed with the electric discharge energy, a plurality of power sources for generating the electric discharge energy, Based on the detection means for detecting the voltage between the electrodes, the discharge stopping means for stopping the discharge by the second power supply for a predetermined time during the discharge by the first power supply, and the voltage detection between the electrodes of the detection means. An electric discharge machining apparatus comprising: a control unit configured to change a discharge stop time of the second power supply of the discharge stop unit according to a voltage value of the first power supply. 3. An electric discharge machining apparatus, wherein a conductive machining fluid is interposed between an electrode and a workpiece to generate an electric discharge, and machining is performed with the electric discharge energy, a plurality of power sources for generating the electric discharge energy, Detection means for detecting the voltage between the electrodes, a capacitor having a variable capacitance connected in parallel between the electrodes, and a discharge stopping means for stopping the discharge by the second power supply for a predetermined time during the discharge by the first power supply. And a control means for changing the discharge stop time of the second power supply of the discharge stop means according to the capacitance of the capacitor based on the voltage detection between the electrodes of the detection means. Electric discharge machine. 4. The electric discharge machining apparatus according to claim 1, further comprising a distance control unit that controls an inter-electrode distance according to the predetermined inter-electrode voltage value. 5. A level change circuit for changing the discharge detection level of the detection circuit is provided.
The electric discharge machining apparatus described in 2 and 3.