WO2016147327A1 - Appareil d'usinage par décharge électrique - Google Patents

Appareil d'usinage par décharge électrique Download PDF

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Publication number
WO2016147327A1
WO2016147327A1 PCT/JP2015/057963 JP2015057963W WO2016147327A1 WO 2016147327 A1 WO2016147327 A1 WO 2016147327A1 JP 2015057963 W JP2015057963 W JP 2015057963W WO 2016147327 A1 WO2016147327 A1 WO 2016147327A1
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Prior art keywords
discharge
voltage
threshold value
absolute value
electrodes
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PCT/JP2015/057963
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English (en)
Japanese (ja)
Inventor
祐飛 佐々木
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三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2015/057963 priority Critical patent/WO2016147327A1/fr
Priority to JP2015560468A priority patent/JP5968565B1/ja
Publication of WO2016147327A1 publication Critical patent/WO2016147327A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H1/00—Electrical discharge machining, i.e. removing metal with a series of rapidly recurring electrical discharges between an electrode and a workpiece in the presence of a fluid dielectric
    • B23H1/02—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges

Definitions

  • the present invention relates to an electric discharge machining apparatus for machining a workpiece by electric discharge machining in which preliminary discharge and main discharge are repeated.
  • An electric discharge machining apparatus is an apparatus that generates a pulsed discharge between an electrode and a workpiece that are disposed opposite to each other in water, and uses the thermal energy to process the workpiece.
  • Patent Document 1 relates to a wire-cut electric discharge machining power supply, including a high voltage main power supply, a low voltage main power supply, a sub power supply, a voltage detection circuit for detecting a gap voltage, and a power supply control circuit for controlling the application timing of each of the three power supplies. It is described that discharge is started by voltage application by a sub power source, and voltages having different pulse widths are applied by a high voltage main power source or a low voltage main power source according to information on a gap voltage after the discharge starts.
  • the electrical discharge machining apparatus performs electrical discharge machining by repeating preliminary discharge and main discharge executed after the preliminary discharge.
  • the workpiece is a multi-element bonding material that is a difficult-to-process material, a high resistance element and a low resistance element having different resistance values are mixed, so that the state of preliminary discharge is not uniform.
  • it is necessary to set the intensity of the discharge pulse of the main discharge in accordance with the resistance value of the element in the workpiece that has generated the preliminary discharge.
  • An object of the present invention is to obtain an electric discharge machining apparatus capable of improving the quality of a processed surface of a multi-element bonded material in electric discharge machining in which preliminary discharge and main discharge are repeated.
  • An electric discharge machining apparatus includes a power source that outputs a voltage applied between electrodes between a electrode and a workpiece, a switch that turns on or off a voltage that the power supply applies to the gap, and the gap between the electrodes.
  • a detection device that detects a discharge state and outputs a detection result; controls a switch using the detection result of the detection device to control a voltage applied between the electrodes; and a first discharge between the electrodes
  • a control device that determines a condition for generating a second discharge between the electrodes based on a change in a discharge state when the voltage is generated.
  • an electric discharge machining apparatus capable of improving the quality of the machined surface of the multi-element bonding material in the electric discharge machining in which the preliminary discharge and the main discharge are repeated.
  • the figure which shows the control apparatus with which the electric discharge machining apparatus which concerns on Embodiment 1 is provided Enlarged view of multi-element combination
  • Enlarged view of multi-element combination Timing chart of electric discharge machining executed by electric discharge machining apparatus according to Embodiment 1 The figure which shows an example of the change by the time of the voltage between electrodes between electrodes and a workpiece or current between electrodes
  • the figure which shows the example which determines main discharge time using change time The figure which shows an example of the table which described the relationship between the material of a workpiece, the 1st threshold value, the 2nd threshold value, a change time threshold value, and the main discharge time.
  • resistance refers to electric resistance
  • FIG. 1 is a diagram illustrating an electric discharge machining apparatus according to the first embodiment.
  • FIG. 2 is a diagram illustrating a control device included in the electric discharge machining apparatus according to the first embodiment.
  • the electric discharge machining apparatus 100 includes power sources 1 and 2 that output a voltage to be applied to the gap 5 that is a gap formed between the electrode 3 and the workpiece 4, and a voltage that the power sources 1 and 2 provide to the gap 5.
  • Switches 9 and 10 that are turned on or off, a detection device 6 that detects the discharge state of the gap 5 and outputs a detection result, and operates the switches 9 and 10 using the detection result of the detection device 6 to open the gap 5 For generating a main discharge as a second discharge in the gap 5 based on a change in the discharge state when a preliminary discharge as the first discharge is generated in the gap 5. And a control device 8 for determining.
  • the electric discharge machining apparatus 100 further includes a moving device 15 that moves the electrode 3 and an input device 8I that inputs control information to the control device 8.
  • the electric discharge machining apparatus 100 processes the workpiece 4 by applying a voltage between the electrode 3 and the workpiece 4 and generating electric discharge between the electrodes 5. Examples of the processing of the workpiece 4 include melt cutting or shape carving.
  • the electrode 3 is a conductor.
  • the electric discharge machining apparatus 100 melts and cuts the workpiece 4, a wire is used for the electrode 3.
  • the electric discharge machining apparatus 100 engraves the workpiece 4, a mold for engraving is used for the electrode 3.
  • the workpiece 4 is a conductor.
  • Power supplies 1 and 2 are DC power supplies.
  • the power source 1 is appropriately referred to as a first power source 1
  • the power source 2 is appropriately referred to as a second power source 2.
  • the voltage of the first power supply 1 is higher than the voltage of the second power supply 2.
  • the electric discharge machining apparatus 100 includes the first power supply 1 and the second power supply 2, but the first power supply 1 is boosted or stepped down by a DC (Direct Current) / DC converter with one power supply.
  • the second power source 2 may be used instead.
  • the switch 9 is provided between the second power source 2, the electrode 3 and the workpiece 4.
  • the switch 10 is provided between the first power source 1, the electrode 3, and the workpiece 4.
  • the switch 10 is appropriately referred to as a first switch 10
  • the switch 9 is appropriately referred to as a second switch 9.
  • the first switch 10 includes switching elements 10A and 10B.
  • the switching elements 10A and 10B are semiconductor elements such as bipolar transistors or FETs (Field Effect Transistors), but are not limited to these.
  • the switching element 10 ⁇ / b> A is provided between the positive electrode of the first power supply 1 and the electrode 3.
  • the switching element 10 ⁇ / b> B is provided between the workpiece 4 and the negative electrode of the first power supply 1.
  • the second switch 9 has switching elements 9A and 9B.
  • the switching elements 9A and 9B are the same as the switching elements 10A and 10B of the first switch 10.
  • the switching element 9 ⁇ / b> A is provided between the positive electrode of the second power supply 2 and the electrode 3.
  • the switching element 9 ⁇ / b> B is provided between the workpiece 4 and the negative electrode of the second power supply 2.
  • the detection device 6 includes a first detection device 6A and a second detection device 6B.
  • the first detection device 6A detects that the absolute value of the voltage at the gap 5 in the preliminary discharge, which is the first discharge, is lower than the absolute value of the first threshold, and outputs the detection result.
  • the second detection device 6B detects that the absolute value of the voltage at the gap 5 in the preliminary discharge is less than the absolute value of the second threshold, and outputs the detection result.
  • both the first detection device 6A and the second detection device 6B use a comparator.
  • the first detection device 6A and the second detection device 6B both detect the voltage between the electrodes 5.
  • the voltage between the electrodes 5 is appropriately referred to as an electrode voltage
  • the current flowing between the electrodes 5 is appropriately referred to as an electrode current.
  • the first detection device 6A compares the detected inter-electrode voltage with the absolute value of the first threshold value, and outputs a signal when the inter-electrode voltage falls below the absolute value of the absolute value of the first threshold value.
  • This signal is a signal indicating that the voltage between the electrodes has fallen below the absolute value of the first threshold, and will be referred to as a first signal as appropriate in the following.
  • the first signal is input to the control device 8.
  • the second detection device 6B compares the detected inter-electrode voltage with the absolute value of the second threshold value.
  • the absolute value of the second threshold value is smaller than the absolute value of the first threshold value.
  • the second detection device 6B outputs a signal when the inter-electrode voltage falls below the absolute value of the second threshold value.
  • This signal is a signal indicating that the inter-electrode voltage has fallen below the absolute value of the second threshold, and will be referred to as a second signal as appropriate hereinafter.
  • the second signal is input to the control device 8.
  • the detection device 6 includes two comparators having different thresholds, that is, the first detection device 6A and the second detection device 6B, but the detection device 6 is not limited to such a configuration.
  • the detection device 6 may switch the threshold value of one comparator.
  • the control device 8 acquires the detection result of the detection device 6 and controls the switches 9 and 10 using the acquired detection result.
  • the control device 8 applies a voltage to the gap 5 by controlling the switches 9 and 10.
  • the control device 8 controls the switches 9 and 10 using the detection result of the detection device 6 to control the interelectrode voltage.
  • the control device 8 changes the time during which the second switch 9 is turned on, so that the magnitude of the peak value of the interelectrode current in the main discharge becomes constant among the plurality of main discharges. To do.
  • control device 8 changes the distance between the electrode 3 and the workpiece 4 by moving the electrode 3 by controlling the moving device 15.
  • the control device 8 receives information necessary for controlling the switches 9 and 10 and the moving device 15 from the input device 8I.
  • the input device 8I is exemplified by a touch panel, a keyboard, a mouse, a trackball, or a combination thereof.
  • Examples of the moving device 15 include a device provided with a linear motor and a table moved by the linear motor, or a device provided with a ball screw, an electric motor for rotating the screw, and a table moved by the ball screw.
  • the control device 8 includes a processing unit 8P, a storage unit 8M, and an input / output unit 8IO.
  • the processing unit 8P is a processor such as a CPU (Central Processing Unit).
  • the storage unit 8M is a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk drive, a storage device, or a storage device that combines these.
  • the input / output unit 8IO is an interface circuit that serves as an interface between the control device 8 and an external device connected to the control device 8.
  • the detection device 6, the switches 9, 10 and the moving device 15 shown in FIG. 1 are connected to the input / output unit 8IO.
  • the storage unit 8M stores a computer program for the control device 8 to execute processing for controlling the electric discharge machining apparatus 100 according to the first embodiment.
  • the processing unit 8P reads the above-described computer program from the storage unit 8M and controls the electric discharge machining apparatus 100.
  • 3 and 4 are enlarged views of the multi-element combination.
  • 3 and FIG. 4 includes an element 51 and an element 52.
  • the resistance values of the elements 51 and 52 and the particle sizes of the elements 51 and 52 are often different.
  • the particle size of the element 52 is larger than that of the element 51.
  • the resistance values of the elements 51 and 52 are different, and as a result, the melting amount of the elements 51 and 52 is different.
  • either of the elements 51 and 52 is melted first. Large elements 52 may fall out and become vacancies.
  • a crater may be formed on the surface and the machining surface may become rough.
  • the electric discharge machining apparatus 100 determines the energy of main discharge so that both elements can be melted in a balanced manner by discriminating between a high resistance element and a low resistance element by preliminary discharge, so that the multi-element bonding material can be stabilized. While processing, improve the quality of the processed surface. Next, processing when the electric discharge machining apparatus 100 according to Embodiment 1 performs electric discharge machining will be described.
  • FIG. 5 is a timing chart of electric discharge machining executed by the electric discharge machining apparatus according to the first embodiment.
  • the electrical discharge machining apparatus 100 performs electrical discharge machining on the workpiece 4, preliminary electrical discharge and main electrical discharge are performed.
  • the preliminary discharge is a discharge for breaking the insulation between the electrode 3 and the workpiece 4 before the workpiece 4 is processed by the discharge.
  • the main discharge is a discharge after dielectric breakdown occurs between the electrode 3 and the workpiece 4 due to the preliminary discharge, and is a discharge for melting the workpiece 4.
  • the electric discharge machining apparatus 100 processes the workpiece 4 by removing a part of the surface of the workpiece 4 by repeating the preliminary discharge and the main discharge over time.
  • FIG. 5 shows the timing of the first control signal 13 for turning on (ON) or turning off (OFF) the first switch 10 in the preliminary discharge.
  • MD in FIG. 5 indicates the timing of the second control signal 14 for turning on (ON) or turning off (OFF) the second switch 9 in the main discharge.
  • V in FIG. 5 indicates an interelectrode voltage
  • I indicates an interelectrode current.
  • a change in the interelectrode voltage V is indicated by a solid line 17
  • a change in the interelectrode current I is indicated by a solid line 18.
  • Vc1 is the first threshold value Vc2 of the interelectrode voltage V
  • Ic1 is the first threshold value of the interelectrode current I
  • Ic2 is the second threshold value of the interelectrode current I. is there.
  • the absolute value of the first threshold value Vc1 is smaller than the absolute value of the second threshold value Vc2.
  • the horizontal axis in FIG. 5 is time t.
  • the control device 8 turns off the first control signal 13, thereby turning off the switching elements 10A and 10B of the first switch 10.
  • the control device 8 turns on the switching elements 9A and 9B of the second switch 9 by turning on the second control signal 14.
  • a voltage is applied between the electrode 3 and the workpiece 4 from the second power source 2 via the second switch 9.
  • the discharge after the preliminary discharge is the main discharge.
  • the inter-electrode current I of the main discharge is larger than the inter-electrode current of the preliminary discharge. Due to the main discharge, the workpiece 4 is melted, a part of the workpiece 4 is removed from the surface, and the processing proceeds.
  • the control device 8 turns off the switching elements 9A and 9B of the second switch 9 and ends the main discharge.
  • the control device 8 determines energy for generating the second discharge between the electrodes based on the change in the discharge state when the first discharge is generated between the electrodes. Specifically, the control device 8 sets the gap 5 between the main discharges based on the amount of time ⁇ tc until the gap voltage V during the preliminary discharge changes from the first threshold value Vc1 to the second threshold value Vc2. A time ⁇ tp for applying the voltage is determined.
  • the time ⁇ tc is appropriately referred to as a change time ⁇ tc
  • the time ⁇ tp is appropriately referred to as a main discharge time ⁇ tp.
  • the inter-electrode voltage V is the voltage of the second power supply 2 and is constant, so the control device 8 changes the main discharge time ⁇ tp by changing the main discharge time ⁇ tp.
  • the control device 8 can determine the magnitude of the resistance of the workpiece 4 using the change time ⁇ tc.
  • the workpiece 4 is a multi-element bonding material including a low resistance element and a high resistance element
  • the change time ⁇ tc is relatively short, that is, when the resistance is relatively low, the ratio of the low resistance element is large and changes
  • the time ⁇ tc is relatively long, that is, when the resistance is relatively high, the ratio of the high resistance element is large.
  • control device 8 can discriminate between the low resistance element ratio and the high resistance element ratio in the workpiece 4 based on the change time ⁇ tc in the preliminary discharge, the main discharge conditions such that both elements can be melted in a balanced manner, that is, The main discharge time ⁇ tp can be determined.
  • the resistivity of WC is 19.2 ⁇ 10 ⁇ 8 ⁇ ⁇ m
  • the resistivity of Co is 5.81 ⁇ 10. Since -8 ⁇ ⁇ m, WC is a high resistance element and Co is a low resistance element.
  • the control device 8 relatively shortens the main discharge time ⁇ tp when the change time ⁇ tc is relatively short, and relatively sets the main discharge time ⁇ tp when the change time ⁇ tc is relatively long. Make it longer.
  • the control device 8 can keep the peak Ip of the interelectrode current I constant between when the resistance of the workpiece 4 is relatively high and when it is relatively low. Generation
  • the electric discharge machining apparatus 100 can suppress the generation of holes in the workpiece 4 and the deterioration of the quality of the machined surface.
  • the change time ⁇ tc is t3 ⁇ t2.
  • FIG. 6 is a diagram illustrating an example of a change in the interelectrode voltage or interelectrode current between the electrode and the workpiece with time.
  • the first threshold value Vc1 of the voltage is a value lower than the interelectrode voltage Vid when the dielectric breakdown of the interelectrode 5 occurs.
  • the first voltage threshold value Vc1 is determined in the range of 80% to 90% of the interelectrode voltage Vid, but is not limited to this range.
  • the second threshold value Vc2 of the voltage is a value higher than the interelectrode voltage Vac when the arc discharge is stably generated in the interelectrode 5.
  • the second voltage threshold Vc2 is determined in the range of 110% to 120% of the interelectrode voltage Vac, but is not limited to this range.
  • the first threshold value Vc1 and the second threshold value Vc2 will be described later.
  • FIG. 7 is a diagram illustrating an example in which the main discharge time is determined using the change time.
  • the main discharge time ⁇ tp becomes longer as the change time ⁇ tc becomes longer, and becomes shorter as the change time ⁇ tc becomes shorter.
  • the change time ⁇ tc is the time during which the state of discharge between the electrodes 5 in the preliminary discharge, that is, the state of the voltage V and the current I between the electrodes in the first embodiment is changed. More specifically, the change time ⁇ tc is a time during which the interelectrode voltage V decreases during the preliminary discharge and the interelectrode current I increases.
  • the shortening of the change time ⁇ tc means that the speed at which the discharge state changes in the gap 5, more specifically, the speed at which the gap voltage V decreases and the gap current I increases decreases.
  • the longer change time ⁇ tc means that the rate of change of the discharge state in the gap 5, more specifically, the rate of decrease of the gap voltage V and increase of the gap current I is increased. .
  • the main discharge time ⁇ tp is ⁇ tph when the change time ⁇ tc is longer than the change time threshold ⁇ tcc as shown by the solid line A in FIG. 7, and the change time ⁇ tc is less than or equal to the change time threshold ⁇ tcc. In this case, ⁇ tpl.
  • the main discharge time ⁇ tph is longer than the main discharge time ⁇ tpl.
  • the change time threshold value ⁇ tcc is determined by an experiment or simulation using a computer according to the type of material of the workpiece 4. In the first embodiment, the change time threshold value ⁇ tcc is set to 100 nsec. 2 ⁇ sec. It is set between.
  • the change time ⁇ tc When the change time ⁇ tc is longer than the change time threshold value ⁇ tcc, the workpiece 4 has a high ratio of high resistance elements. When the change time ⁇ tc is less than or equal to the change time threshold value ⁇ tcc, the workpiece 4 has a low resistance element ratio. It can be judged that it is expensive. In this way, by changing the main discharge time ⁇ tp in two stages with the change time threshold value ⁇ tcc as a reference, the process of determining the main discharge time ⁇ tp by the control device 8 becomes relatively simple.
  • the main discharge time ⁇ tp is not limited to the one that changes in two steps as described above, and may change in three or more steps as shown by a one-dot chain line B in FIG. Further, the main discharge time ⁇ tp may follow a function of the change time ⁇ tc in which the main discharge time ⁇ tp increases as the change time ⁇ tc increases.
  • the function in this case may be a linear function of the change time ⁇ t as shown by a broken line C in FIG. 7, or may be a quadratic function, a cubic function or an exponential function of the change time ⁇ tc.
  • the main discharge times ⁇ tpl and ⁇ tph, the change in the main discharge time ⁇ tp indicated by the alternate long and short dash line B, or the function of the change time ⁇ tc described above can be obtained for each material of the workpiece 4 by experiments or simulations using a computer. .
  • FIG. 8 is a diagram showing an example of a table describing the relationship between the material of the workpiece, the first threshold value, the second threshold value, the change time threshold value, and the main discharge time.
  • the first threshold value Vc1, the second threshold value Vc2, the change time threshold value ⁇ tcc, and the main discharge times ⁇ tpl and ⁇ tph vary depending on the type of material of the workpiece 4.
  • the first threshold value Vc1, the second threshold value Vc2, the change time threshold value ⁇ tcc, and the main discharge times ⁇ tpl and ⁇ tph are obtained and described in the table TB according to the material type of the workpiece 4. To do.
  • the table TB is stored in the storage unit 8M of the control device 8 shown in FIG.
  • the operator of the electric discharge machining apparatus 100 inputs the material type of the workpiece 4 from the input device 8I shown in FIG.
  • the processing unit 8P that has acquired the type of the input material reads the table TB from the storage unit 8M. Then, the processing unit 8P uses the material type as a search key, refers to the read table TB, and inputs the first threshold value Vc1, the second threshold value Vc2, the change time threshold value ⁇ tcc, and the main value.
  • the discharge times ⁇ tpl and ⁇ tph are retrieved and obtained from the table TB.
  • the control device 8 controls the first switch 10 and the second switch 9 by using the acquired first threshold value Vc1, second threshold value Vc2, change time threshold value ⁇ tcc, and main discharge times ⁇ tpl and ⁇ tph, to process the workpiece.
  • the object 4 is subjected to electric discharge machining.
  • the electric discharge machining apparatus 100 can perform electric discharge machining on the workpiece 4 under appropriate conditions when electric discharge machining is performed on the workpiece 4 of a plurality of different types of materials. It is possible to suppress degradation of the quality of the processed surface.
  • FIG. 9 is a flowchart showing an example of processing when the electric discharge machining apparatus according to Embodiment 1 executes electric discharge machining.
  • the control device 8 shown in FIG. 1 turns on the first switch 10 to apply the first voltage, which is the voltage of the first power supply 1, between the electrode 3 and the workpiece 4.
  • the processing unit 8P compares the interelectrode voltage V with the first threshold value Vc1.
  • step S102, No the control device 8 waits until the inter-electrode voltage V falls below the absolute value of the first threshold value Vc1.
  • the control device 8 performs the process in step S103. Proceed to In step S103, the control device 8 starts counting time from the timing when the inter-electrode voltage V falls below the absolute value of the first threshold value Vc1.
  • step S104 the processing unit 8P compares the interelectrode voltage V with the second threshold value Vc2.
  • the control device 8 waits until the inter-electrode voltage V falls below the absolute value of the second threshold value Vc2.
  • the control device 8 performs the process at step S105. Proceed to
  • step S105 the control device 8 finishes counting the time, and obtains the change time ⁇ tc using the counted time. Furthermore, the control device 8 applies a second voltage, which is the voltage of the second power supply 2, between the electrode 3 and the workpiece 4 by turning on the second switch 9. By this operation, a main discharge is generated between the electrode 3 and the workpiece 4. The control device 8 starts counting time from the timing when the second switch 9 is turned on, that is, the timing when the main discharge is started. Next, it progresses to step S106 and the control apparatus 8 calculates
  • DELTA main discharge time
  • DELTA change time
  • step S107 the control device 8 compares the elapsed time ts from the timing of starting the main discharge with the main discharge time ⁇ tp. When the elapsed time ts has not reached the main discharge time ⁇ tp (step S107, No), the control device 8 waits until the elapsed time ts reaches the main discharge time ⁇ tp. When the elapsed time ts has reached the main discharge time ⁇ tp (step S107, Yes), in step S108, the control device 8 ends the main discharge by turning off the second switch 9. When Step S101 to Step S108 are completed, the control device 8 returns to Step S101 and repeats Step S101 to Step S108 until the electrical discharge machining of the workpiece 4 is completed.
  • FIG. 10 is a diagram illustrating a second switch according to the first modification of the first embodiment.
  • the peak Ip of the interelectrode current I is made constant between different main discharges by changing the main discharge time ⁇ tp.
  • the peak Ip of the interelectrode current I is made constant between different main discharges by changing the interelectrode voltage V.
  • the second switch 9a includes a voltage adjusting device 9Aa provided between the positive electrode of the second power source 2 and the electrode 3, and a switching element 9B provided between the negative electrode of the second power source 2 and the workpiece 4. .
  • a voltage adjusting device 9Aa provided between the positive electrode of the second power source 2 and the electrode 3, and a switching element 9B provided between the negative electrode of the second power source 2 and the workpiece 4.
  • a plurality of switching elements 16TA, 16TB, 16TC, and 16TD connected in series and a plurality of resistors 16RA, 16RB, 16RC, and 16RD connected in series are connected in parallel.
  • the plurality of switching elements 16TA, 16TB, 16TC, and 16TD are turned on and off by the control device 8, respectively.
  • the switching elements 16TA, 16TB, 16TC, and 16TD are semiconductor elements such as bipolar transistors or FETs (Field Effect Transistors), but are not limited to these.
  • the voltage adjusting device 9Aa has the highest resistance when all of the plurality of switching elements 16TA, 16TB, 16TC, and 16TD are turned off. When the switching elements 16TA, 16TB, 16TC, and 16TD are turned on in this order, the resistance gradually increases. Lower.
  • the voltage regulator 9Aa has the lowest resistance when all of the plurality of switching elements 16TA, 16TB, 16TC, and 16TD are turned on.
  • the voltage regulator 9Aa can change the voltage drop between the second power supply 2 and the electrode 3 by switching on and off the plurality of switching elements 16TA, 16TB, 16TC, and 16TD. For this reason, the 2nd switch 9a provided with voltage regulator 9Aa can change the voltage V between electrodes.
  • the control device 8 When the interelectrode voltage V is applied between the electrode 3 and the workpiece 4 by the second switch 9a, the control device 8 turns on at least the switching element 9B.
  • the switching element 9B When only the switching element 9B is turned on, since all the resistors 16RA, 16RB, 16RC, and 16RD of the voltage regulator 9Aa are interposed between the second power source 2 and the electrode 3, the interpolar voltage V is the smallest. Become.
  • the switching element 9B and at least one of the plurality of switching elements 16TA, 16TB, 16TC, and 16TD are turned on, the inter-electrode voltage V becomes larger than when only the switching element 9B is turned on.
  • the control device 8 controls the voltage adjustment device 9Aa of the second switch to increase the inter-electrode voltage V.
  • the control device 8 controls the voltage adjustment device 9Aa of the second switch to decrease the interelectrode voltage V.
  • the voltage adjustment device 9Aa includes a plurality of switching elements 16TA, 16TB, 16TC, and 16TD and a plurality of resistors 16RA, 16RB, 16RC, and 16RD, but is not limited thereto.
  • the voltage adjusting device 9Aa may be a DC / DC converter, or a device having a plurality of DC power sources having different voltages and a switch for selecting a power source for supplying a voltage to the gap 5 from the plurality of DC power sources. There may be.
  • the detection device 6 shown in FIG. 1 detects the interelectrode voltage V, but may detect the interelectrode current I.
  • the first detection device 6A compares the detected interelectrode current I with the first threshold value Ic1 of the current shown in FIG. 5, and the interelectrode current I exceeds the absolute value of the first threshold value Ic1.
  • the first signal is output.
  • the second detection device 6B compares the detected interelectrode current I with the second threshold value Ic2 of the current.
  • the absolute value of the second threshold value Ic2 is larger than the absolute value of the first threshold value Ic1.
  • the second detection device 6B outputs a second signal when the interelectrode current I exceeds the absolute value of the second threshold value Ic2.
  • the first threshold value Ic1 and the second threshold value Ic2 of the current can be the current I between the electrodes when the voltage V between the electrodes is the first threshold value Vc1 and the second threshold value Vc2.
  • the control device 8 continues to turn on the first switch 10 until dielectric breakdown occurs.
  • the first switch 10 continues until dielectric breakdown occurs.
  • the voltage may be applied to the gap 5 by repeatedly turning on and off.
  • the detection device 6 determines the absolute value of the interelectrode current I, the absolute value of the first threshold value Ic1 of the current, and the second value.
  • the change time ⁇ tc is obtained using the absolute value of the threshold value Ic2. In this way, the detection device 6 can obtain the change time ⁇ tc regardless of the processing conditions.
  • the control device 8 when the control device 8 keeps turning on the first switch 10 until the dielectric breakdown occurs, the change time ⁇ tc using the inter-electrode voltage V and the first threshold value Vc1 and the second threshold value Vc2. If the first switch 10 is repeatedly turned on and off until dielectric breakdown occurs, the change time ⁇ tc may be obtained using the interelectrode current I and the first threshold value Ic1 and the second threshold value Ic2. . And the control apparatus 8 may determine the voltage given to the space
  • DELTA calculated
  • the change time ⁇ tc is the time from the timing when the interelectrode current I exceeds the absolute value of the first threshold value Ic1 to the timing when the interelectrode current I exceeds the absolute value of the second threshold value Ic2.
  • the control device 8 determines the voltage applied to the gap 5 in the main discharge based on the change time ⁇ tc in which the gap voltage V in the preliminary discharge changes, and the gap in the preliminary discharge. Based on the change time ⁇ tc during which the current I changes, the voltage applied to the gap 5 in the main discharge may be switched depending on the form of the preliminary discharge.
  • the electric discharge machining apparatus 100 can obtain the change time ⁇ tp even under various machining conditions, an appropriate main discharge time ⁇ tp can be set for the workpiece 4.
  • the electric discharge machining apparatus 100 can suppress the generation of holes in the workpiece 4 and the quality degradation of the machined surface under various machining conditions.
  • FIG. FIG. 11 is a diagram illustrating an electric discharge machining apparatus according to the second embodiment.
  • the electrical discharge machining apparatus 100b includes a switch, more specifically, the first switch 10b includes a bridge circuit and a detection device 6b, and applies positive and negative voltages from the first power supply 1 to the gap 5 to each other.
  • Other structures of the electric discharge machining apparatus 100b according to the second embodiment are the same as those of the electric discharge machining apparatus 100 according to the first embodiment.
  • the first switch 10b is provided between the first power source 1, the electrode 3, and the workpiece 4.
  • the first switch 10b forms a bridge circuit by a plurality of switching elements 10A, 10B, 10C, and 10D.
  • the switching elements 10A, 10B, 10C, and 10D are semiconductor elements such as bipolar transistors or FETs (Field Effect Transistors), but are not limited thereto.
  • Switching elements 10A and 10C form the upper arm of the bridge circuit, and switching elements 10B and 10D form the lower arm of the bridge circuit.
  • a connection part between the switching element 10A and the switching element 10D is connected to the electrode 3, and a connection part between the switching element 10C and the switching element 10B is connected to the workpiece 4.
  • the control device 8 controls the plurality of switching elements 10A, 10B, 10C, and 10D.
  • the switching element 10A and the switching element 10B When the switching element 10A and the switching element 10B are turned on, the positive electrode of the first power supply 1 and the electrode 3 are connected, and the negative electrode of the first power supply 1 and the workpiece 4 are connected. For this reason, the interelectrode current I flows from the electrode 3 toward the workpiece 4.
  • the switching element 10C and the switching element 10D When the switching element 10C and the switching element 10D are turned on, the positive electrode of the first power source 1 and the workpiece 4 are connected, and the negative electrode of the first power source 1 and the electrode 3 are connected. For this reason, the interelectrode current I flows from the workpiece 4 toward the electrode 3.
  • the detection device 6b includes a first detection device 6A, a second detection device 6B, a third detection device 6C, and a fourth detection device 6D.
  • the first detection device 6A and the second detection device 6B are the same as those described in the first embodiment.
  • Each of the third detection device 6C and the fourth detection device 6D detects the interelectrode voltage.
  • the third detection device 6C compares the detected inter-electrode voltage with the absolute value of the third threshold value, and outputs a signal when the inter-electrode voltage falls below the absolute value of the absolute value of the first threshold value. This signal is a signal indicating that the inter-electrode voltage has fallen below the absolute value of the third threshold value, and is hereinafter referred to as a third signal as appropriate.
  • the third signal is input to the control device 8.
  • the fourth detection device 6D compares the detected inter-electrode voltage with a fourth threshold value.
  • the absolute value of the fourth threshold value is smaller than the absolute value of the third threshold value.
  • the fourth detection device 6D outputs a signal when the inter-electrode voltage falls below the absolute value of the fourth threshold value.
  • This signal is a signal indicating that the inter-electrode voltage has fallen below the absolute value of the fourth threshold value, and is hereinafter referred to as a fourth signal as appropriate.
  • the fourth signal is input to the control device 8.
  • the detection device 6b includes four comparators having different thresholds, that is, the first detection device 6A, the second detection device 6B, the third detection device 6C, and the fourth detection device 6D. 6b is not limited to such a thing.
  • the detection device 6b may switch the threshold value of one comparator.
  • FIG. 12 is a timing chart of electric discharge machining executed by the electric discharge machining apparatus according to the second embodiment.
  • PD1 in FIG. 12 indicates the timing of the first control signal 27 for turning on or off the switching element 10A and the switching element 10B of the first switch 10b in the preliminary discharge.
  • PD2 in FIG. 12 indicates the timing of the first control signal 28 for turning on or off the switching element 10C and the switching element 10D of the first switch 10b in the preliminary discharge.
  • 12 indicates the timing of the second control signal 29 for turning on or off the second switch 9 in the main discharge.
  • V indicates the interelectrode voltage
  • I indicates the interelectrode current.
  • a change in the interelectrode voltage V is indicated by a solid line 36, and a change in the interelectrode current I is indicated by a solid line 39.
  • Vc1 is the first threshold value of the interelectrode voltage V
  • Vc2 is the second threshold value of the interelectrode voltage V
  • Vc3 is the third threshold value of the interelectrode voltage V
  • Vc4 is the fourth threshold value of the interelectrode voltage V. It is.
  • the third threshold value Vc3 is a negative voltage having the same absolute value as the first threshold value Vc1.
  • the fourth threshold value Vc4 is a negative voltage having the same absolute value as the second threshold value Vc2.
  • Ic1 is a first threshold value of the interelectrode current I
  • Ic2 is a second threshold value of the interelectrode current I
  • Ic3 is a third threshold value of the interelectrode current I
  • Ic4 is a fourth threshold value of the interelectrode current I. It is.
  • the absolute value of the first threshold value Ic1 is smaller than the absolute value of the second threshold value Ic2.
  • the absolute value of the first threshold value Ic1 is equal to the absolute value of the third threshold value Ic3, and the absolute value of the second threshold value Ic2 is equal to the absolute value of the fourth threshold value Ic4.
  • the horizontal axis of FIG. 12 is time t.
  • the control device 8 turns on the switching element 10A and the switching element 10B according to the control signal 27, applies the electrode 3 as positive and applies the interelectrode voltage V to the electrode 3 and the workpiece 4, and generates a preliminary discharge in the interelectrode 5
  • the control device 8 determines the main discharge time ⁇ tp1 using the change time ⁇ tc1 obtained by the preliminary discharge, and turns on the second switch 9 to generate the main discharge in the gap 5.
  • the control device 8 When the main discharge based on the preliminary discharge with the electrode 3 as positive is completed, the control device 8 turns on the switching element 10C and the switching element 10D by the control signal 28, and applies the voltage V between the electrodes with the workpiece 4 as positive. It gives to the workpiece 4 and the electrode 3 and a preliminary discharge is generated between the electrodes 5.
  • the control device 8 determines the main discharge time ⁇ tp2 using the change time ⁇ tc2 obtained by this preliminary discharge, and turns on the second switch 9 to generate the main discharge in the gap 5.
  • the change time ⁇ tc2 is the fourth threshold value Vc4 at which the absolute value of the interelectrode voltage V is the absolute value of the interelectrode voltage V from the timing when the absolute value of the interelectrode voltage V falls below the absolute value of the third threshold value Vc3 of the interelectrode voltage V This is the time until the timing when the absolute value is below.
  • the control device 8 When the main discharge based on the preliminary discharge with the workpiece 4 as positive is completed, the control device 8 turns on the switching element 10A and the switching element 10B according to the control signal 27, makes the electrode 3 positive, and sets the electrode voltage V to the electrode. 3 and the workpiece 4 and a preliminary discharge is generated between the electrodes 5.
  • the control device 8 determines the main discharge time ⁇ tp3 using the change time ⁇ tc3 obtained by this preliminary discharge, and turns on the second switch 9 to generate the main discharge in the gap 5.
  • the control device 8 causes the preliminary discharge with the electrode 3 as positive and the main discharge based on the preliminary discharge, the preliminary discharge with the workpiece 4 as positive, and this The main discharge based on the preliminary discharge is executed alternately with the elapse of time t. Since the electric discharge machining apparatus 100b alternately applies a positive voltage and a negative voltage to the electrode 3, the average voltage between the electrodes 5 can be 0 volts. As a result, in addition to the operation and effect of the electric discharge machining apparatus 100 according to the first embodiment, the electric discharge machining apparatus 100b suppresses the electric corrosion of the workpiece 4 even when the machining liquid is water, thereby reducing the quality of the machined surface. The effect
  • the detection device 6b shown in FIG. 11 detects the interelectrode voltage V, but may detect the interelectrode current I.
  • the third detection device 6C compares the detected interelectrode current I with the third threshold value Ic3 shown in FIG. 12, and the absolute value of the interelectrode current I exceeds the absolute value of the third threshold value Ic3.
  • the third signal is output.
  • the fourth detection device 6D compares the detected interelectrode current I with a fourth threshold value Ic4.
  • the absolute value of the fourth threshold value Ic4 is larger than the absolute value of the third threshold value Ic3.
  • the fourth detection device 6D outputs a fourth signal when the absolute value of the interelectrode current I exceeds the absolute value of the fourth threshold value Ic4. Since the first detection device 6A and the second detection device 6B are the same as those in the first embodiment, the description thereof is omitted.
  • the control device 8 continues to turn on the first switch 10b until dielectric breakdown occurs, as shown in FIG. 12, but depending on the processing conditions, the first switch 10b until the dielectric breakdown occurs.
  • the voltage may be applied to the gap 5 by repeatedly turning on and off.
  • the detection device 6b determines that the absolute value of the interelectrode voltage V is the absolute value of the first threshold value Vc1, the absolute value of the second threshold value Vc2, the absolute value of the third threshold value Vc3, and the fourth value. It is difficult to detect that the absolute value of the threshold value Vc4 is below the absolute value.
  • the detection device 6b detects the absolute value of the interelectrode current I, the absolute value of the first threshold Ic1 of the current, the second The change time ⁇ tc is obtained using the absolute value of the threshold value Ic2, the absolute value of the third threshold value Ic3, and the absolute value of the fourth threshold value Ic4. In this way, the detection device 6b can obtain the change time ⁇ tc regardless of the processing conditions.
  • the change time ⁇ tc is the time from the timing when the interelectrode current I exceeds the absolute value of the third threshold value Ic3 to the timing when the interelectrode current I exceeds the absolute value of the fourth threshold value Ic4. It is.
  • the control device 8 when the control device 8 continues to turn on the first switch 10 until dielectric breakdown occurs, the inter-electrode voltage V, the first threshold value Vc1, the second threshold value Vc2, the third threshold value Vc3, and the first threshold value Vc3.
  • the change time ⁇ tc is obtained using the threshold value Vc4 of 4 and the first switch 10 is repeatedly turned on and off until dielectric breakdown occurs, the interelectrode current I, the first threshold value Ic1, the second threshold value Ic2, The change time ⁇ tc may be obtained using the third threshold value Ic3 and the fourth threshold value Ic4.
  • the electric discharge machining apparatus 100b can obtain the change time ⁇ tp even under various machining conditions, so that the main discharge time ⁇ tp appropriate for the workpiece 4 can be set. As a result, the electric discharge machining apparatus 100b can suppress the generation of holes in the workpiece 4 and the deterioration of the quality of the machined surface under various machining conditions.
  • 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.

Abstract

L'invention concerne un appareil d'usinage par décharge électrique (100) qui comprend : des sources d'énergie (1, 2) pour fournir une tension devant être appliquée à travers un espace entre électrodes (5) entre une électrode (3) et une pièce à travailler (4) ; des commutateurs (9, 10) pour commuter la tension que lesdites sources d'énergie (1, 2) appliquent à travers ledit espace entre électrodes en service et hors service ; un dispositif de détection (6) pour détecter l'état de décharge dans l'espace entre électrodes (5) et fournir les résultats de détection ; un dispositif de commande (8) pour commander les commutateurs (9, 10), utilisant les résultats du dispositif de détection (6) pour commander la tension appliquée dans l'espace entre électrodes (5), et, sur la base de changements dans l'état de décharge quand une première décharge est générée dans l'espace entre électrodes (5), pour déterminer les conditions pour générer une deuxième décharge dans l'espace entre électrodes (5). Il est ainsi obtenu un appareil d'usinage par décharge électrique (100) pour effectuer de manière répétée une décharge préliminaire et une décharge principale, avec lequel la qualité de la surface usinée d'un matériau conjugué à éléments multiples peut être améliorée.
PCT/JP2015/057963 2015-03-17 2015-03-17 Appareil d'usinage par décharge électrique WO2016147327A1 (fr)

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CN113618179B (zh) * 2021-09-03 2023-02-28 牧野机床（中国）有限公司 一种电火花线切割机床及控制方法

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JP5409964B1 (ja) * 2012-10-30 2014-02-05 三菱電機株式会社 ワイヤ放電加工装置
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JPS49108697A (fr) * 1973-02-19 1974-10-16
US4078163A (en) * 1975-06-04 1978-03-07 Bell Jr Oliver A Programmable current control system for wire electrode electrical discharge machining apparatus
US20140083980A1 (en) * 2012-09-25 2014-03-27 Industrial Technology Research Institute Apparatus and method for electrical discharge machining modulation control
JP5409964B1 (ja) * 2012-10-30 2014-02-05 三菱電機株式会社 ワイヤ放電加工装置

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Publication number Priority date Publication date Assignee Title
JP2019181617A (ja) * 2018-04-09 2019-10-24 ファナック株式会社 ワイヤ放電加工機およびワイヤ放電加工方法
JP7128014B2 (ja) 2018-04-09 2022-08-30 ファナック株式会社 ワイヤ放電加工機およびワイヤ放電加工方法

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