JPWO2016199301A1 - EDM power supply - Google Patents

Abstract

An electric discharge machining power supply device includes: an electrode for passing a current between the workpiece and a first power supply unit for applying a voltage to a first path connected between the workpiece and the electrode; , A transformer disposed in the second path connected between the poles, and a voltage in a direction to suppress a current flowing from the first power supply unit to the stray capacitance of the second path through the transformer And a second power supply unit that applies to the path.

Description

  The present invention relates to an electric discharge machining power supply apparatus for machining a workpiece by generating an electric discharge between an electrode and the workpiece.

  An electric discharge machine is an apparatus that performs arc discharge by generating an arc discharge between electrodes formed by opposing electrodes and a workpiece, and melting and removing the workpiece. The electrode and the workpiece are placed in a highly insulating liquid. Examples of the highly insulating liquid include deionized water or oil.

  The electrical discharge machine uses a rough machining current with a relatively long time width, and rough machining that places importance on machining speed while leaving a finishing machining cost in the subsequent process, and gradually reduces the energy of the current pulse. And finishing to reduce the surface roughness of the workpiece. The time width of the rough machining current is exemplified by several tens of microseconds. The pulse width of the current pulse in the finishing process is exemplified by several tens of nanoseconds.

  In rough machining, it is known that a rough machining current having a short time width and a high peak value is desirable. In order to realize a rough machining current having a short time width and a high peak value, a discharge circuit generally used in rough machining is a transistor discharge circuit. In the transistor discharge circuit, a rough machining current having a short time width and a high peak value can be obtained by detecting the occurrence of discharge and controlling the discharge current with the transistor.

  In finishing, it is required to shorten the current pulse width in order to reduce the surface roughness of the surface to be processed. Therefore, in the finishing process, an RC circuit including a current limiting resistor arranged in series between the power source and the gap and an inter-pole parallel capacitor arranged in parallel with the gap is used.

  The RC circuit includes a power source for applying a voltage between the electrodes, a current limiting resistor for limiting a current from the power source, and an inter-electrode parallel capacitor for storing discharge energy. Further, although not present as an element on the circuit, there exists a stray capacitance that is a capacitance included in the mechanical structure or cable.

  In the RC circuit, when a power supply voltage is applied, electric charges are stored in the interpolar parallel capacitor and the stray capacitance, and the interpolar voltage rises. The time constant τ of the voltage increase is determined by the product of the current limiting resistor and the interpolar parallel capacitor. Therefore, the larger the inter-pole parallel capacitor, the lower the voltage increase rate.

  When the voltage between the electrodes rises, the insulation between the electrodes is broken, and the charge stored in the parallel capacitor between the electrodes and the stray capacitance flows between the electrodes. The workpiece is melted and removed by the heat generated by this electric current, whereby finishing is performed.

  In the RC circuit, if the capacitance component between the electrodes is reduced, the surface roughness of the surface to be processed can be reduced. Therefore, a minute capacitance component can be configured with only stray capacitance without arranging an inter-electrode parallel capacitor. In order to further reduce the surface roughness of the work surface, it is necessary to improve the structure of the electric discharge machine to reduce the stray capacitance itself or to take an electrical circuit measure to cancel the influence of the stray capacitance.

As a related technology, Patent Document 1 below, in order to improve the surface roughness of the finish machining, recently arranged inductance L _T of the tool electrode 6 to suppress a steep current during discharge electric discharge machining apparatus Is described (see FIG. 2).

JP 59-42222 A

However, in the electric discharge machining apparatus disclosed in Patent Document 1, all of the discharge current so through the inductance L _T, is the current also inhibited in rough machining requiring large currents inherent and adversely affect the roughing There was a problem. Further, since the parasitic capacitance C ₂ exists as it is, it is necessary to charge the parasitic capacitance C ₂ in order to increase the voltage between the tool electrode 6 and the workpiece 4. There was a problem that the increase rate of the voltage between them became slow.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an electric discharge machining power supply device that can suppress the influence of stray capacitance.

  In order to solve the above-described problems and achieve the object, the present invention provides a first electrode connected between an electrode for passing an electric current between the workpiece and an electrode constituted by the workpiece and the electrode. The first power supply unit for applying a voltage to the path, the transformer disposed in the second path connected between the electrodes, and the current flowing from the first power supply unit to the stray capacitance of the second path are suppressed. And a second power supply unit that applies a voltage in the direction to the second path through a transformer.

  The electric discharge machining power supply apparatus according to the present invention has an effect that the influence of stray capacitance can be suppressed.

The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 1. FIG. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure which shows the waveform of each part of the electric discharge machining power supply apparatus concerning Embodiment 1. The flowchart which shows the process of the control part of the electric discharge machining power supply device concerning Embodiment 1. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure which shows the waveform of the voltage between electrodes of the electric discharge machining power supply device concerning Embodiment 1. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure which shows the waveform of the electric current between electrodes of the electric discharge machining power supply device concerning Embodiment 1. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 1. FIG. The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 2. FIG. The figure which shows the waveform of each part of the electric discharge machining power supply device concerning Embodiment 2. The flowchart which shows the process of the control part of the electric discharge machining power supply device concerning Embodiment 2. The figure explaining operation | movement of the electrical discharge machining power supply apparatus concerning Embodiment 2. FIG. The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 3. The figure which shows mounting of the electric discharge machining power supply device concerning Embodiment 3. The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 4. FIG. The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 5. The figure which shows the circuit structure of the electric discharge machining power supply device concerning Embodiment 6.

  Hereinafter, an electric discharge machining power supply apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a circuit configuration of the electric discharge machining power supply apparatus according to the first embodiment. The electric discharge machining power supply device 1 applies a voltage to the first path A <b> 1 connected to the electrode 2 that flows current between the workpiece 3 and the gap 4 constituted by the workpiece 3 and the electrode 2. Current flowing from the first power supply unit 5 to the stray capacitance 7 of the second path A2 and the transformer 6 disposed in the second path A2 connected to the gap 4 A second power supply unit 8 that applies a voltage in a suppressing direction to the second path A2 via the transformer 6 and a control unit 9 that controls the second power supply unit 8 are provided.

  The 1st power supply part 5 is connected to the electrode 2 via the cable C1, and is connected to the workpiece 3 via the cable C2. The first route A1 includes cables C1 and C2.

  The first power supply unit 5 induces electric discharge in the gap 4 during rough machining, and induces electric discharge in the gap 4 during finishing and processes the workpiece 3 with a discharge current. It is a power source for. In the field of electric discharge machines, the first power supply unit 5 may be called a sub power supply. Examples of the first power supply unit 5 include an RC discharge circuit, a transistor discharge circuit, and a high-frequency power supply circuit that are generally used in an electric discharge machine. However, the first power supply unit 5 is not limited to these, and various circuits can be employed. In the first embodiment, the first power supply unit 5 is an RC discharge circuit.

  The secondary winding 6 b of the transformer 6 is inserted into a cable C 3 connected to the electrode 2. One end of the cable C3 is connected to the electrode 2, and the other end of the cable C3 is connected to one end of the connection object 10 via the switch SW1. The other end of the connection object 10 is connected to the workpiece 3 via the switch SW2 and the cable C4. The primary winding 6 a of the transformer 6 is connected to the second power supply unit 8. The second path A2 includes cables C3 and C4.

  The second power supply unit 8 employs a power supply adapted to the configuration or control method of the first power supply unit 5 in order to suppress the influence of the stray capacitance 7 on the processing.

  The transformer 6 can apply a voltage from the second power supply unit 8 to the second path A2 while insulating the second power supply unit 8 from the second path A2.

  The connection object 10 connected to the second path A2 includes various substrates for detecting the state of the gap 4, a power supply for rough machining for supplying a rough machining current to the gap 4, or a casing of an electric discharge machine. Is exemplified. The connection object 10 is not limited to one, and may be plural. In the first embodiment, the connection object 10 is the third power supply unit 10 for supplying a rough machining current to the gap 4. In the first embodiment, the third power supply unit 10 is a transistor discharge circuit.

  When roughing is not performed, the third power supply unit 10 is disconnected from the cables C3 and C4 with the switches SW1 and SW2 turned off, but even in this case, the stray capacitance is between the cables C3 and C4. 7 exists. The second path A2 includes a cable C3, a stray capacitance 7, and a cable C4.

  The third power supply unit 10 is a power source for processing the workpiece 3 by supplying a rough machining current to the gap 4 where discharge is induced during rough machining. In the field of electric discharge machines, the third power supply unit 10 may be called a main power supply.

  The third power supply unit 10 has a positive side connected to the workpiece 3 via the switch SW2 and the cable C4, and a source-drain path connected between the negative side of the DC power source 10a and the switch SW1. And a gate signal supply unit 10c that supplies a gate signal to the gate of the transistor 10b.

  When the gate signal supply unit 10c supplies a high-level gate signal to the gate of the transistor 10b, the transistor 10b is turned on and a rough machining current flows between the gaps 4.

  Based on the gate signal supplied to the gate of the transistor 10 b by the gate signal supply unit 10 c and the voltage between the electrodes 4 detected by the voltage sensor 11, the control unit 9 includes the first control signal 9 a and the second control signal 9 a. A control signal 9 b is supplied to the second power supply unit 8.

  In the first embodiment, the first power supply unit 5 and the third power supply unit 10 do not supply voltage or current to the gap 4 at the same time. Therefore, the present invention is applicable to the electric discharge machining power supply device 1.

  The operation of the electric discharge machining power supply device 1 will be described. In the first embodiment, the electric discharge machining power supply device 1 performs rough machining.

  When performing rough machining, first, the first power supply unit 5 applies a voltage to the gap 4 to induce discharge in the gap 4. When a discharge occurs between the electrodes 4, the third power supply unit 10 passes a rough machining current through the electrodes 4.

  When the first power supply unit 5 applies a voltage to the gap 4, the first discharge voltage application pattern in which the electrode 2 is on the positive electrode side and the workpiece 3 is on the negative electrode side, and the workpiece 3 is on the positive electrode side. And a second discharge voltage application pattern in which the electrode 2 is on the negative electrode side. Which one of the first discharge voltage application pattern and the second discharge voltage application pattern is adopted is determined by conditions. Examples of the conditions include the type or configuration of the electric discharge machine.

  On the other hand, the third power supply unit 10 generally supplies a rough machining current in the direction from the workpiece 3 to the electrode 2 in order to increase the amount of machining removal of the workpiece 3 in the rough machining.

  In the first embodiment, the operation of the electric discharge machining power supply device 1 when the first discharge voltage application pattern is adopted will be described first, and later, the electric discharge machining power supply when the second discharge voltage application pattern is adopted. The operation of the device 1 will be described.

FIG. 2 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. As shown in FIG. 2, first, at timing t ₀ , the first power supply unit 5 has a first discharge voltage application pattern in which the electrode 2 is on the positive electrode side and the workpiece 3 is on the negative electrode side. applying the voltages _{V 1} to the path A1.

FIG. 3 is a diagram illustrating waveforms of respective parts of the electric discharge machining power supply apparatus according to the first embodiment. At timing t ₀ , when the first power supply unit 5 applies the voltage V ₁ to the first path A 1 in the first discharge voltage application pattern in which the electrode 2 is on the positive electrode side and the workpiece 3 is on the negative electrode side. As shown by the waveform 31 in FIG. 3, the inter-electrode voltage V between the inter-electrodes 4 rises.

  FIG. 4 is a flowchart of a process performed by the control unit of the electric discharge machining power supply apparatus according to the first embodiment.

  In step S <b> 100, the control unit 9 determines whether or not the voltage sensor 11 has detected that a voltage has been applied to the gap 4. When it is determined that the voltage sensor 11 has not detected that a voltage has been applied to the gap 4 (No), the control unit 9 waits in step S100, and that the voltage has been applied to the gap 4 If it determines with having detected by 11 (Yes), a process will be advanced to step S102.

  In step S102, the control unit 9 controls the second power supply unit 8 so as to apply a voltage in a direction to suppress the current flowing from the first power supply unit 5 to the stray capacitance 7 to the second path A2. . Specifically, as shown by the waveform 35 in FIG. 3, the control unit 9 turns on the first control signal 9a, that is, sets it to the high level.

FIG. 5 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. When the first power supply unit 5 applies the voltage V1 to the _first path A1 in the first discharge voltage application pattern, the current I1 flows through the _first path A1. Further, the current I ₂ flows into the gap 4, the electric charge due to the current I ₂ is stored in the capacity of the gap 4, and the gap voltage V between the gaps 4 increases. Further, the current _{I 3} flowing into the second path A2. Here, I ₁ = I ₂ + I ₃ .

Therefore, the control unit 9, the voltage V ₂ in the direction of suppressing the current I ₃ flowing into the stray capacitance 7 from the first power supply unit 5 to apply the second path A2, a second power supply unit 8 Control. The voltage _{V 2,} the current _{I 4} flows through the second path A2. Here, the direction of the current I ₄ is opposite to the direction of the current I ₃ .

As a result, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₃ −I ₄ . Therefore, the electric discharge machining power supply device 1 can suppress the current I ₀ flowing into the stray capacitance 7.

The difference between the magnitude of the current I _{4 and} the magnitude of the current I ₃ is preferably small, and the magnitude of the current I ₄ is more preferably the same as the magnitude of the current I ₃ . In this way, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₃ −I ₄ = 0, and the electric discharge machining power supply device 1 further suitably uses the current I ₀ flowing into the stray capacitance 7. Can be suppressed. Thereby, the electric discharge machining power supply device 1 can set the current I ₂ flowing into the gap 4 to I ₂ = I ₁ and can increase the current I ₂ .

As described above, the electric discharge machining power supply device 1 can suppress the current I ₀ flowing into the stray capacitance 7 so that the stray capacitance 7 is reduced. Assuming that the capacitance between the electrodes 4 is C _A and the capacitance of the stray capacitance 7 is C _B , the charge Q stored in the interelectrode 4 and the stray capacitance 7 is Q = (C _A + C _B ) according to the basic equation of the capacitor. XV.

The electric discharge machining power supply device 1 suppresses the current I ₀ flowing into the stray capacitance 7 so that the stray capacitance 7 is reduced, so that the charge Q ′ stored in the gap 4 is changed to Q ′ = C _A × V. That is, electrical discharge machining power supply apparatus 1 can reduce the amount corresponding capacitance of the capacitor C _B of the stray capacitance 7, to reduce the charge amount Q 'for increasing the inter-electrode voltage V.

FIG. 6 is a diagram illustrating a waveform of an interelectrode voltage of the electric discharge machining power supply apparatus according to the first embodiment. In the first embodiment, the first power supply unit 5 is an RC discharge circuit. In the RC discharge circuit, when the resistance value of the RC discharge circuit is R, the rise time of the interelectrode voltage V is determined by a time constant τ = R × (C _A + C _B ).

The electric discharge machining power supply apparatus 1 sets the time constant τ ′ of the rise time of the interelectrode voltage V to τ ′ = R × C _A as if the stray capacitance 7 is reduced by suppressing the current I _0. It can be. In other words, the electric discharge machining power supply device 1 can reduce the capacitance by the capacitance C ₇ of the stray capacitance 7 and reduce the time constant τ ′ of the rise time of the interelectrode voltage V.

  Therefore, as shown by the waveform 31 in FIG. 6, the electric discharge machining power supply device 1 causes the rise of the inter-electrode voltage V from the inter-electrode voltage waveform 41 when the second power supply unit 8 and the transformer 6 are not provided. Can also be accelerated by time 42.

The electrical discharge machining power supply device 1 can obtain the following effects by increasing the rise of the interelectrode voltage V. First, the electric discharge machining power supply device 1 can shorten the time required for rough machining. Second, discharge machining power supply unit 1, by increasing the time inter-electrode voltage V becomes a voltage V _1, and easily generate a discharge in the machining gap 4, the discharge at the machining gap 4 is generated Can increase the probability.

Returning to the description of the operation of the electric discharge machining power supply device 1. When discharge occurs between the electrodes 4 at the timing t ₁ , the current I flows between the electrodes 4 as shown by the waveform 32 in FIG. 3, and as indicated by the waveform 31 in FIG. In addition, the interelectrode voltage V decreases.

  At this time, charges are stored in the gap 4 but no charge is stored in the stray capacitance 7, so the time during which the current I flows is shortened.

Discharge occurs between the electrodes 4, when the inter-electrode current I flows in the machining gap 4, at timing t _2, the gate signal supply unit 10c of the third power source unit 10, as shown by the waveform 33 in FIG. 3, The gate signal supplied to the gate of the transistor 10b is turned on, that is, set to the high level.

FIG. 7 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. At timing t _2, the gate signal is turned on, the transistor 10b is turned on. As a result, the third power supply unit 10 applies the voltage V ₃ that sets the workpiece 3 to the positive side and the electrode 2 to the negative side to the second path A 2, and travels from the workpiece 3 to the electrode 2. direction, flow roughing current _{I 5.} By the third power source unit 10 of the shed the rough machining current I ₅ in the machining gap 4, as shown by the waveform 32 in FIG. 3, rises interelectrode current I flowing between the electrodes 4, inter-electrode current I increases start.

  Referring to FIG. 4 again, the control unit 9 determines in step S104 whether or not the voltage sensor 11 has detected that a discharge has occurred between the electrodes 4. That is, the control unit 9 determines whether or not the voltage sensor 11 has detected that the interelectrode voltage V has decreased. If the controller 9 determines that the discharge between the electrodes 4 has not been detected by the voltage sensor 11 (No), the control unit 9 waits at step S104, and the voltage sensor 11 determines that the discharge has occurred between the electrodes 4. If it determines with having detected (Yes), a process will be advanced to step S106.

  In step S106, the controller 9 determines whether or not the gate signal is turned on. If it is determined that the gate signal is not turned on (No), the controller 9 stands by in step S106, and if it is determined that the gate signal is turned on (Yes), the process proceeds to step S108.

Control unit 9, in step S108, to apply the direction of increasing voltage rough machining current I ₅ in the second path A2, controls the second power supply unit 8. Specifically, as shown by the waveform 34 in FIG. 3, the control unit 9 turns on the second control signal 9b, that is, sets it to the high level.

FIG. 8 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. When the third power supply unit 10 applies the voltage V ₃ to the second path A 2, a rough machining current I ₅ flows through the gap 4.

Control unit 9, the direction of the voltage V ₄ to increase the rough machining current I ₅ flowing through the machining gap 4 so as to apply to the second path A2, controls the second power supply unit 8. The voltage _{V 4,} the current _{I 6} flows through the second path A2. Here, the direction of the current I ₆ is the same as the direction of the rough machining current I ₅ .

Therefore, the electric discharge machining power supply device 1 can increase the interelectrode current I flowing between the interelectrodes 4 to I = I ₅ + I _6, and can speed up the rise of the interelectrode current I. When the inter-electrode current I flows through the inter-electrode 4, rough machining of the workpiece 3 is performed.

Next, at timing t ₃ , the gate signal supply unit 10 c of the third power supply unit 10 turns off the gate signal supplied to the gate of the transistor 10 b, as shown by the waveform 33 in FIG.

When the gate signal is turned off at timing t ₃ , the transistor 10 b is turned off, and the third power supply unit 10 finishes applying the voltage V ₃ . Thereby, as shown by the waveform 32 in FIG. 3, the inter-electrode current I flowing between the inter-electrodes 4 starts to decrease.

  Referring to FIG. 4 again, the control unit 9 determines whether or not the gate signal is turned off in step S110. If it is determined that the gate signal is not turned off (No), the control unit 9 stands by in Step S110, and if it is determined that the gate signal is turned off (Yes), the process proceeds to Step S112.

Control unit 9, in step S112, so as to apply a voltage direction of suppressing the second path A2 rough machining current I _5, controls the second power supply unit 8. Specifically, as shown by the waveform 35 in FIG. 3, the control unit 9 turns on the first control signal 9a, that is, sets it to the high level.

  In step S114, the controller 9 determines whether or not a predetermined time has elapsed. When it is determined that the predetermined time has not elapsed (No), the control unit 9 waits in step S114. If it is determined that the predetermined time has elapsed (Yes), the control unit 9 advances the process to step S116.

The predetermined time period from the timing t ₃ to time t _4, i.e. inter-electrode current I is the time from when started to decline until interelectrode current I becomes zero.

  In step S116, the control unit 9 controls the second power supply unit 8 to end the output of the voltage to the second path A2, and ends the process.

FIG. 9 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. Control unit 9, the voltage V ₅ direction of suppressing the rough machining current I ₅ flowing through the machining gap 4 so as to apply to the second path A2, controls the second power supply unit 8. The voltage _{V 5,} the current _{I 7} flows through the second path A2. Here, the direction of the current I ₇ is opposite to the direction of the rough machining current I ₅ . Therefore, the electric discharge machining power supply apparatus 1 can suppress the inter-electrode current I flowing between the inter-electrodes 4 to I = I ₅ −I ₇ .

FIG. 10 is a diagram illustrating a waveform of the interelectrode current of the electric discharge machining power supply apparatus according to the first embodiment. EDM power supply unit 1, between the time t ₀ to time t _2, the voltage V ₂ in the direction of suppressing the current I ₃ flowing into the stray capacitance 7 from the first power supply portion 5 to the second path A2 Apply. As a result, no charge is stored in the stray capacitance 7.

Therefore, the electric discharge machining power supply device 1 can make the rise of the interelectrode voltage V faster. Thus, electric discharge machining power source device 1, as compared to the waveform 43 in the case where the second is not provided power supply unit 8 and the transformer 6, the peak of the inter-electrode current I between the timing t ₁ to timing t ₂ the it is possible to reduce, it is possible to shorten the time it flows electrode current I from the timing t ₁ to timing t _2.

The electrical discharge machining power supply device 1 can obtain the following effects by increasing the rise of the interelectrode voltage V. EDM power supply unit 1, by increasing the time inter-electrode voltage V reaches the voltage V _1, and easily generate a discharge in the machining gap 4, increase the probability of discharge in the machining gap 4 is generated be able to. Thereby, since the electric discharge machining power supply device 1 can increase the machining removal amount per unit time, the rough machining speed can be improved.

Further, electrical discharge machining power supply unit 1, between the time t ₂ to time t _3, i.e. the period during which the rough machining current I ₅ is increased, the rough machining current I ₅ of the third power source unit 10 of the shed between the electrodes 4 applying a direction of the voltage V ₄ that increases the second path A2.

Therefore, electric discharge machining power supply unit 1, as compared to the waveform 43 in the case where not provided a second power supply unit 8 and the transformer 6, the peak of the current between the electrodes I between the timing t ₂ to time t ₃ it is possible to increase, it is possible to shorten the time from the timing t ₂ to time t _3.

Further, electrical discharge machining power supply unit 1, between the time t ₃ to time t _4, that is, in the period in which the rough machining current I ₅ decreases, the rough machining current I voltage V ₅ direction of suppressing the ₅ second Applied to the path A2. Therefore, electric discharge machining power supply unit 1, as compared to the waveform 43 of the current between the electrodes when no provided with the second power supply unit 8 and the transformer 6, electrode current I from the timing t ₃ to time t ₄ is The time to decrease can be shortened.

  As a result, the electric discharge machining power supply device 1 can pass the inter-electrode current I having a short time width and a high peak value, which is required for rough machining, to the inter-electrode 4. Thereby, the electrical discharge machining power supply device 1 can realize suitable rough machining.

Further, the electric discharge machining power supply device 1 supplies a current from the second power supply unit 8 and the transformer 6 to the second path A2, so that the rough machining by the third power supply unit 10 is performed from the discharge by the first power supply unit 5. The current can be supplied to the gap 4 before the current I ₅ is supplied, and the energy efficiency can be improved.

  Next, the operation of the electric discharge machining power supply device 1 when the second discharge voltage application pattern is adopted will be described.

FIG. 11 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. As shown in FIG. 11, first, at timing t ₀ , the first power supply unit 5 uses the second discharge voltage application pattern in which the workpiece 3 is on the positive electrode side and the electrode 2 is on the negative electrode side. the voltage _{V 11} is applied to the path A1.

  In step S <b> 100, the control unit 9 determines whether or not the voltage sensor 11 has detected that a voltage has been applied to the gap 4. When it is determined that the voltage sensor 11 has not detected that a voltage has been applied to the gap 4 (No), the control unit 9 waits in step S100, and that the voltage has been applied to the gap 4 If it determines with having detected by 11 (Yes), a process will be advanced to step S102.

  In step S102, the control unit 9 controls the second power supply unit 8 so as to apply a voltage in a direction to suppress the current flowing from the first power supply unit 5 to the stray capacitance 7 to the second path A2. .

FIG. 12 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the first embodiment. The first power supply unit 5, when a voltage is applied to V ₁₁ to the first path A1 in the second discharge voltage application pattern, the current I ₁₁ flows through the first path A1. In addition, the current I ₁₂ flows into the gap 4, the charge due to the current I ₁₂ is stored in the capacitance of the gap 4, and the voltage of the gap 4 increases. The current _{I 13} flows into the second path A2. Here, I ₁₁ = I ₁₂ + I ₁₃ .

Therefore, the control unit 9, the current I ₁₃ voltage V ₁₂ direction of suppressing the flowing into the stray capacitance 7 from the first power supply unit 5 to apply the second path A2, a second power supply unit 8 Control. The voltage _{V 12,} a current _{I 14} flows through the second path A2. Here, the direction of the current I ₁₄ is opposite to the direction of the current I ₁₃ .

As a result, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₁₃ −I ₁₄ . Therefore, the electric discharge machining power supply device 1 can suppress the current I ₀ flowing into the stray capacitance 7.

The magnitude of the current I ₁₄ is preferably close to the magnitude of the current I _{13, and} the magnitude of the current I ₁₄ is more preferably the same as the magnitude of the current I ₁₃ . In this way, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₁₃ −I ₁₄ = 0, and the electric discharge machining power supply device 1 further suitably uses the current I ₀ flowing into the stray capacitance 7. Can be suppressed. Thereby, the electric discharge machining power supply device 1 can set the current I ₁₂ flowing through the gap 4 to I ₁₂ = I _11, and can increase the current I ₁₂ .

  The subsequent operation of the electric discharge machining power supply device 1 is the same as that when the first discharge voltage application pattern described above is employed.

  Even when the second discharge voltage application pattern is adopted, the electric discharge machining power supply device 1 has the same effect as when the first discharge voltage application pattern is adopted.

Embodiment 2. FIG.
FIG. 13 is a diagram illustrating a circuit configuration of the electric discharge machining power supply device according to the second embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The electric discharge machining power supply device 1A applies a voltage to the first path A1 connected to the electrode 2 for passing a current between the workpiece 3 and the gap 4 formed by the workpiece 3 and the electrode 2. Current flowing from the first power supply unit 5 to the stray capacitance 7 of the second path A2 and the transformer 6 disposed on the second path A2 connected to the gap 4 A second power supply unit 8 that applies a voltage in a direction to suppress the current to the second path A2 via the transformer 6, and a control unit 9 that controls the second power supply unit 8.

  In the second embodiment, the electric discharge machining power supply device 1A performs finishing machining. Therefore, the connection object 12 connected to the second path A2 may be the third power supply unit 10 or another object. Other examples include various substrates for detecting the state of the gap 4 or the case of an electric discharge machine.

  When the first power supply unit 5 applies a voltage to the gap 4, the first discharge voltage application pattern in which the electrode 2 is on the positive electrode side and the workpiece 3 is on the negative electrode side, and the workpiece 3 is on the positive electrode side. And a second discharge voltage application pattern in which the electrode 2 is on the negative electrode side. Which one of the first discharge voltage application pattern and the second discharge voltage application pattern is adopted is determined by conditions. Examples of the conditions include the type or configuration of the electric discharge machine.

The operation of the electric discharge machining power supply device 1A when the first discharge voltage application pattern is adopted will be described. As shown in FIG. 13, first, at a timing t _10, the first power supply portion 5, and the electrode 2 on the positive side in the first discharge voltage applying pattern to the workpiece 3 on the negative electrode side, a first applying a voltage _{V 21} on path A1.

FIG. 14 is a diagram illustrating waveforms of the respective parts of the electric discharge machining power supply apparatus according to the second embodiment. At timing t _10, the first power supply unit 5 is, in the first discharge voltage applying pattern to the workpiece 3 and the electrode 2 on the positive side to the negative, when a voltage is applied to V ₂₁ to the first path A1 As shown by the waveform 51 in FIG. 14, the inter-electrode voltage V between the inter-electrodes 4 rises.

  FIG. 15 is a flowchart of a process performed by the control unit of the electric discharge machining power supply apparatus according to the second embodiment.

  In step S <b> 100, the control unit 9 determines whether or not the voltage sensor 11 has detected that a voltage has been applied to the gap 4. When it is determined that the voltage sensor 11 has not detected that a voltage has been applied to the gap 4 (No), the control unit 9 waits in step S100, and that the voltage has been applied to the gap 4 If it determines with having detected by 11 (Yes), a process will be advanced to step S102.

  In step S102, the control unit 9 controls the second power supply unit 8 so as to apply a voltage in a direction to suppress the current flowing from the first power supply unit 5 to the stray capacitance 7 to the second path A2. . Specifically, the control unit 9 turns on the first control signal 9a, that is, sets it to the high level.

FIG. 16 is a diagram for explaining the operation of the electric discharge machining power supply apparatus according to the second embodiment. The first power supply unit 5, when a voltage is applied to V ₂₁ to the first path A1 in the first discharge voltage application pattern, the current I ₂₁ flows through the first path A1. Further, the current I ₂₂ flows into the gap 4, the electric charge due to the current I ₂₂ is stored in the capacitance between the gaps 4, and the gap voltage V between the gaps 4 increases. The current _{I 23} flows into the second path A2. Here, I ₂₁ = I ₂₂ + I ₂₃ .

Therefore, the control unit 9, the first voltage V ₂₂ direction of suppressing the current I ₂₃ flowing from the power supply unit 5 to the stray capacitance 7 as applied to the second path A2, a second power supply unit 8 Control. The voltage _{V 22,} a current _{I 24} flows through the second path A2. Here, the direction of the current I ₂₄ is opposite to the direction of the current I ₂₃ .

As a result, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₂₃ −I ₂₄ . Therefore, electric discharge machining power supply apparatus 1A, it is possible to suppress the current I ₀ flowing into the stray capacitance 7.

The difference between the magnitude of the current I _{24 and} the magnitude of the current I ₂₃ is preferably small, and the magnitude of the current I ₂₄ is more preferably the same as the magnitude of the current I ₂₃ . In this way, the current I ₀ flowing through the second path A2 becomes I ₀ = I ₂₃ −I ₂₄ = 0, and the electric discharge machining power supply apparatus 1A further suitably uses the current I ₀ flowing into the stray capacitance 7. Can be suppressed. Thereby, the electric discharge machining power supply device 1A can set the current I ₂₂ flowing into the gap 4 to I ₂₂ = I ₂₁ and can increase the current I ₂₂ .

Thus, electric discharge machining power supply apparatus 1A, by suppressing the current I ₀ flowing into the stray capacitance 7 can as if to make the stray capacitance 7 is reduced. Assuming that the capacitance between the electrodes 4 is C _A and the capacitance of the stray capacitance 7 is C _B , the charge Q stored in the interelectrode 4 and the stray capacitance 7 is Q = (C _A + C _B ) according to the basic equation of the capacitor. XV.

The electric discharge machining power supply device 1A suppresses the current I ₀ flowing into the stray capacitance 7 so that the stray capacitance 7 is reduced, so that the charge Q ′ stored in the gap 4 is Q ′ = C _A × V. That is, electrical discharge machining power supply apparatus 1A can reduce the amount corresponding capacitance of the capacitor C _B of the stray capacitance 7, to reduce the charge amount Q 'for increasing the inter-electrode voltage V.

In the second embodiment, the first power supply unit 5 is an RC discharge circuit. In the RC discharge circuit, when the resistance value of the RC discharge circuit is R, the rise time of the interelectrode voltage V is determined by a time constant τ = R × (C _A + C _B ).

EDM power supply 1A, by suppressing the current I _0, as if by such stray capacitance 7 is reduced, the machining gap voltage constant tau 'the τ' = R × C _A when the rise time of V It can be. That is, electrical discharge machining power supply apparatus 1A can amount corresponding to reduce the capacitance of the capacitor C ₇ of the stray capacitance 7, to reduce the constant tau 'the time of the rising time of the inter-electrode voltage V.

  Therefore, the electric discharge machining power supply device 1A can make the rise of the interelectrode voltage V faster than the interelectrode voltage when the second power supply unit 8 and the transformer 6 are not provided.

The electrical discharge machining power supply device 1A can obtain the following effects by increasing the rise of the interelectrode voltage V earlier. First, the electrical discharge machining power supply device 1A can shorten the time required for finishing. Second, the electrical discharge machining power supply device 1A makes it easy to generate a discharge at the inter-electrode distance 4 by increasing the time during which the inter-electrode voltage V is at the voltage V ₂₁ , so that the discharge at the inter-electrode space 4 does not occur. Can be suppressed.

Returning to the description of the operation of the electric discharge machining power supply device 1A. At timing t _11, the discharge in the machining gap 4 is generated by the first power supply portion 5, as shown by waveform 52 in FIG. 14, inter-electrode current I clogging finishing current flows between the electrodes 4, the waveform of FIG. 14 As indicated by 51, the interelectrode voltage V decreases.

  At this time, charges are stored in the gap 4 but no charge is stored in the stray capacitance 7, so the time during which the current I flows is shortened.

  Referring to FIG. 15 again, in step S104, the control unit 9 determines whether or not the voltage sensor 11 has detected that a discharge has occurred between the electrodes 4. That is, the control unit 9 determines whether or not the voltage sensor 11 has detected that the interelectrode voltage V has decreased. If the controller 9 determines that the discharge between the electrodes 4 has not been detected by the voltage sensor 11 (No), the control unit 9 waits at step S104, and the voltage sensor 11 determines that the discharge has occurred between the electrodes 4. If it determines with having detected (Yes), a process will be advanced to step S105.

  In step S105, the control unit 9 controls the second power supply unit 8 so as to end the application of the voltage. Specifically, the control unit 9 turns off the first control signal 9a, that is, sets it to a low level. And the control part 9 complete | finishes a process.

As a result, the second power supply unit 8 can prevent the current I ₂₄ from being superimposed on the inter-electrode current I, that is, the finishing current, when a discharge occurs between the inter-electrode 4.

EDM power apparatus 1A between the timing _{t 10} to the timing _{t 11,} the first voltage _{V 22} direction of suppressing the current _{I 23} flowing from the power supply unit 5 to the stray capacitance 7 in the second path A2 Apply. As a result, no charge is stored in the stray capacitance 7.

Therefore, the electric discharge machining power supply device 1A can accelerate the rise of the interelectrode voltage V. Thus, electric discharge machining power supply apparatus 1A, as compared with the case of not provided with the second power supply unit 8 and the transformer 6, suppressing the peak of the current between the electrodes I between the timing t ₁₁ to the timing t ₁₂ it is possible, it is possible to shorten the electrode current I flows time from the timing t ₁₁ to the timing t _12.

  The electric discharge machining power supply apparatus 1A can reduce the amount of energy per discharge by suppressing the peak of the interelectrode current I and reducing the time during which the interelectrode current I flows. Thereby, 1 A of electric discharge machining power supplies can make the surface roughness of the to-be-processed surface fine after finishing.

The electrical discharge machining power supply device 1A can obtain the following effects by increasing the rise of the interelectrode voltage V earlier. The electric discharge machining power supply device 1A makes it easy to generate a discharge at the inter-electrode distance 4 by increasing the time during which the inter-electrode voltage V reaches the voltage V ₂₁ , and increases the probability of the discharge at the inter-electrode space 4 occurring. be able to. As a result, the electric discharge machining power supply apparatus 1A can increase the machining removal amount per unit time, so that the finishing machining speed can be improved.

  Even when the electric discharge machining power supply apparatus 1A adopts the second discharge voltage application pattern, the control unit 9 sets the voltage in the direction to suppress the current flowing from the first power supply unit 5 to the stray capacitance 7 in the second path A2. What is necessary is just to control the 2nd power supply part 8 so that it may apply to.

Embodiment 3 FIG.
FIG. 17 is a diagram illustrating a circuit configuration of the electric discharge machining power supply device according to the third embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1 and Embodiment 2, and description is abbreviate | omitted.

  An electric discharge machining power supply device 1B according to the third embodiment includes a toroidal transformer 21 instead of the transformer 6 of the electric discharge machining power supply device 1 according to the first embodiment.

  The toroidal transformer 21 includes a toroidal core 21a. A winding 21b is wound around the toroidal core 21a. The winding 21 b is connected to the second power supply unit 8. The cable C3 is passed through the opening 21c of the toroidal core 21a.

  Since the operation of the electric discharge machining power supply apparatus 1B is the same as that of the electric discharge machining power supply apparatus 1 according to the first embodiment, the description thereof is omitted.

  The electric discharge machining power supply device 1 </ b> B includes a toroidal transformer 21 instead of the transformer 6. The toroidal transformer 21 has a high degree of freedom of attachment. Therefore, the electric discharge machining power supply device 1B has an effect that the mounting becomes easy.

  FIG. 18 is a diagram illustrating the mounting of the electric discharge machining power supply device according to the third embodiment. The electrode 2 is stretched between a lower block 23a and an upper block 23b arranged in the processing tank 22. The workpiece 3 is also disposed in the processing tank 22. In the processing tank 22, a highly insulating liquid is stored. Examples of the highly insulating liquid include deionized water or oil. The toroidal core 21 is disposed at a location near the lower block 23 a in the processing tank 22.

  The stray capacitance 7 at a location away from the gap 4 can be separated from the circuit by a mechanical switch. However, it is difficult to separate the stray capacitance 7 near the gap 4 from the circuit with a mechanical switch. Moreover, it is difficult to arrange the transformer 6 at a location close to the extreme.

  According to the electric discharge machining power supply device 1 </ b> B, the toroidal transformer 21 can be disposed at a location close to the gap 4 inside the machining tank 22. Thereby, the electrical discharge machining power supply device 1B can suppress the influence of the stray capacitance 7 in a place with a high dielectric constant in the liquid.

Embodiment 4 FIG.
FIG. 19 is a diagram illustrating a circuit configuration of an electric discharge machining power supply apparatus according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1 to Embodiment 3, and description is abbreviate | omitted.

  The electric discharge machining power supply device 1C according to the fourth embodiment performs finishing as in the electric discharge machining power supply device 1A according to the second embodiment.

  The electric discharge machining power supply device 1C is configured by replacing the first power supply unit 5, the second power supply unit 8 and the control unit 9 of the electric discharge machining power supply device 1A according to the second embodiment with the fourth power supply unit 31 and the second power supply unit 31. A transformer 32 is provided.

  The fourth power supply unit 31 is connected to the primary winding 32 a of the second transformer 32. The secondary winding 32b of the second transformer 32 is connected to the cables C1 and C2. The tertiary winding 32 c of the second transformer 32 is connected to the primary winding 6 a of the transformer 6.

When the fourth power source 31 outputs a voltage to the primary winding 32a of the second transformer 32, the secondary winding 32b and the voltage is induced in, together with the voltage V ₂₁ is applied to the first path A1 , is induced a voltage in the tertiary winding 32c, the voltage _{V 22} is applied to the second path A2.

  That is, the fourth power supply unit 31, the primary winding 32a and the secondary winding 32b of the second transformer 32 correspond to the first power supply unit 5 of the electric discharge machining power supply device 1A according to the second embodiment. Further, the fourth power supply unit 31, the primary winding 32a and the tertiary winding 32c of the second transformer 32 correspond to the second power supply unit 8 of the electric discharge machining power supply device 1A according to the second embodiment.

  Therefore, the electric discharge machining power supply device 1C has the same effects as the electric discharge machining power supply device 1A according to the second embodiment.

  The electric discharge machining power supply apparatus 1C can reduce the number of parts, reduce the cost, and reduce the occupied space.

Embodiment 5. FIG.
FIG. 20 is a diagram illustrating a circuit configuration of an electric discharge machining power supply device according to the fifth embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1 to Embodiment 4, and description is abbreviate | omitted.

  The electric discharge machining power supply device 1D according to the fifth embodiment performs rough machining in the same manner as the electric discharge machining power supply device 1 according to the first embodiment.

  In addition to the configuration of the electrical discharge machining power supply device 1C according to the fourth embodiment, the electrical discharge machining power supply device 1D includes a first winding 32c between the tertiary winding 32c of the second transformer 32 and the primary winding 6a of the transformer 6. 2 control part 41 is further provided.

  The process of the second control unit 41 is the same as the process of the control unit 9 of the electric discharge machining power supply device 1 according to the first embodiment shown in the flowchart of FIG.

  The electric discharge machining power supply device 1D has the same effect as the electric discharge machining power supply device 1 according to the first embodiment.

  The electric discharge machining power supply device 1D can reduce the number of parts, reduce the cost, and reduce the occupied space.

Embodiment 6 FIG.
FIG. 21 is a diagram illustrating a circuit configuration of the electric discharge machining power supply device according to the sixth embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1 to Embodiment 5, and description is abbreviate | omitted.

  An electric discharge machining power supply apparatus 1E according to the sixth embodiment includes a toroidal transformer 21 instead of the transformer 6 of the electric discharge machining power supply apparatus 1C according to the fourth embodiment, and a second toroidal transformer 33 instead of the second transformer 32. Is provided. The toroidal transformer 21 includes a toroidal core 21a, and the second toroidal transformer 33 includes a second toroidal core 33a.

  The fourth power supply unit 31 is connected to the primary winding 33 b of the second toroidal transformer 33. The secondary winding 33c of the second toroidal transformer 33 is connected to the cables C1 and C2. The tertiary winding 33 d of the second toroidal transformer 33 is connected to the primary winding 21 b of the toroidal transformer 21.

When the fourth power source 31 outputs a voltage to the primary winding 33b of the second toroidal transformer 33, is induced voltage in the secondary winding 33c, the voltage V ₂₁ is applied to the first path A1 together, is induced a voltage in the tertiary winding 33d, the voltage _{V 22} is applied to the second path A2.

  Therefore, the electric discharge machining power supply device 1E has the same effect as the electric discharge machining power supply device 1C according to the fourth embodiment.

  The electric discharge machining power supply device 1E can reduce the number of parts, reduce the cost, and reduce the occupied space.

  The electric discharge machining power supply apparatus 1 </ b> E includes a toroidal transformer 21 instead of the transformer 6, and includes a second toroidal transformer 33 instead of the second transformer 32. The toroidal transformer 21 and the second toroidal transformer 33 have a high degree of freedom of attachment. Therefore, the electric discharge machining power supply device 1E has an effect that the mounting becomes easy.

  According to the electric discharge machining power supply device 1E, the toroidal transformer 21 and the second toroidal transformer 33 can be arranged at a location close to the gap 4 inside the machining tank 22. Thereby, the electrical discharge machining power supply device 1E can suppress the influence of the stray capacitance 7 in a place having a high dielectric constant in the liquid.

  The electrical discharge machining power supply device 1E further includes the second control unit 41 described in the fifth embodiment between the tertiary winding 33d of the second toroidal transformer 33 and the winding 21b of the toroidal transformer 21. May be. In this way, the electric discharge machining power supply device 1E can perform rough machining as in the fifth embodiment.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1, 1A, 1B, 1C, 1D, 1E Electric discharge machining power supply device, 2 electrodes, 3 workpieces, 4 poles, 5 first power supply, 6 transformer, 7 stray capacitance, 8 second power supply, 9 Control part, 10 3rd power supply part, 21 Toroidal transformer, 31 4th power supply part, 32 2nd transformer, 33 2nd toroidal transformer, 41 2nd control part.

Claims (7)

An electrode for passing an electric current between the workpiece and the workpiece;
A first power supply for applying a voltage to a first path connected between the workpiece and the electrode; and
A transformer disposed in a second path connected between the poles;
A second power supply unit that applies a voltage in a direction to suppress a current flowing from the first power supply unit to the stray capacitance of the second path to the second path through the transformer;
An electric discharge machining power supply device comprising:   The apparatus further includes a control unit that controls the second power supply unit so as to apply a voltage in a direction that suppresses a current flowing from the first power supply unit to the stray capacitance of the second path to the second path. The electric discharge machining power supply device according to claim 1. When a discharge occurs between the electrodes due to a voltage applied by the first power supply unit, the device further includes a third power supply unit that causes a rough machining current to flow between the electrodes via the second path,
The controller is
In the period in which the rough machining current increases, the second power supply unit is controlled to apply a voltage in the direction of increasing the rough machining current to the second path, and in the period in which the rough machining current decreases. 3. The electric discharge machining power supply device according to claim 2, wherein the second power supply unit is controlled to apply a voltage in a direction to suppress the rough machining current to the second path.   The electric discharge machining power supply device according to claim 1, wherein the transformer is a toroidal transformer.   The electric discharge machining power supply device according to claim 4, wherein the toroidal transformer is arranged in a machining tank in which the gap is arranged. The first power supply unit includes a fourth power supply unit, a primary winding and a secondary winding of a second transformer,
2. The electric discharge machining power supply device according to claim 1, wherein the second power supply unit includes the fourth power supply unit, a primary winding and a tertiary winding of the second transformer. .   The electric discharge machining power supply device according to claim 6, wherein each of the transformer and the second transformer is a toroidal transformer.

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