WO2009096027A1 - 放電加工装置 - Google Patents
放電加工装置 Download PDFInfo
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- WO2009096027A1 WO2009096027A1 PCT/JP2008/051554 JP2008051554W WO2009096027A1 WO 2009096027 A1 WO2009096027 A1 WO 2009096027A1 JP 2008051554 W JP2008051554 W JP 2008051554W WO 2009096027 A1 WO2009096027 A1 WO 2009096027A1
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- discharge
- discharge pulse
- electrode
- pulse
- machining
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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
- B23H1/022—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges for shaping the discharge pulse train
Definitions
- the present invention relates to an electric discharge machining apparatus for machining a workpiece by electric discharge, and in particular, an electric discharge machining apparatus that performs machining by combining two types of discharge pulses composed of a predischarge pulse and a main discharge pulse applied alternately. It is about.
- the electric discharge machining apparatus is an apparatus for machining a workpiece by applying a voltage between a machining electrode and the workpiece to generate an arc discharge.
- As the electric discharge machining apparatus there is a wire electric discharge machining apparatus that uses a thin metal wire as a machining electrode and performs machining using an arc discharge generated between the wire electrode and the workpiece in a machining fluid. .
- a machining pulse is applied between an electrode and a workpiece (hereinafter also referred to as “between electrodes”) in order to generate an arc discharge.
- This machining pulse is generated in a circuit configuration with high impedance and is applied for the purpose of inducing and detecting discharge and processing in the circuit configuration with low impedance generated after detection of discharge. In some cases, it is composed of main discharge pulses.
- Patent Document 1 discloses a conventional technique in which electric discharge machining is performed by combining a preliminary discharge pulse and a main discharge pulse.
- a circuit including a first DC power source that is a main discharge power source for applying a main discharge pulse, and second and third DC power sources that are respectively preliminary discharge power sources for applying a preliminary discharge pulse.
- a main discharge circuit in which a first switch and a first DC power source are connected in series, a positive electrode side of the first DC power source is connected to a workpiece, and a negative electrode side is connected to an electrode; a second switch; Two DC power sources connected in series, a negative polarity pre-discharge circuit in which the positive side of the second DC power source is connected to the electrode and the negative side is connected to the work piece, a third switch and a third DC power source
- a wire machining discharge device is described which is connected in series and has a positive polarity predischarge circuit in which a positive electrode side of a third DC power source is connected to a workpiece and a negative electrode side is connected to an electrode.
- the positive and negative preliminary discharge circuits are alternately closed, and in either case, the main discharge current from the main
- the preliminary discharge pulse is generated by alternately using the second DC power supply and the third DC power supply, and the polarities applied to the wire electrode and the workpiece are mutually I try to replace them.
- This has the effect of preventing electrolytic corrosion when water is used as the working fluid. That is, when machining with a direct current, if the average value of the interelectrode voltage is not zero but has a polarity, an electric field current flows through the machining fluid, and the surface of the workpiece is softened.
- the third DC power supply By alternately using the third DC power supply, the absolute value of the average voltage between the poles can be made close to zero, thereby preventing the workpiece surface from being softened.
- arc discharge has different processing characteristics between the cathode and the anode. That is, the processing characteristics differ depending on whether the workpiece is processed as a cathode or the anode is processed. For this reason, the main discharge pulse that greatly contributes to machining is generated under “positive polarity” in which the workpiece is a positive electrode and the wire electrode is a negative electrode.
- the polarity in which the workpiece is positive and the electrode is negative is called “positive polarity”
- the polarity in which the workpiece is negative and the electrode is positive is called “reverse polarity (or negative polarity)”.
- Patent Document 1 by turning on the second switch, a current flows through a negative polarity predischarge circuit, and a predischarge pulse is applied between the electrodes. Subsequently, when the discharge is detected, the second switch is turned off and the first switch is turned on, whereby a current flows in the main discharge circuit, and the main discharge pulse is supplied between the electrodes.
- the pulse width of the main discharge pulse is defined as a period t2. Subsequently, by stopping the main discharge pulse, the current flowing in the floating reactor is regenerated, and at the same time, there is a pause time that becomes a sinking time between the electrodes.
- the third switch Thereafter, by turning on the third switch, a current flows through the positive-polarity predischarge circuit, and a predischarge pulse having a polarity different from the previous one is applied between the electrodes. Further, the third switch is turned off at the time when the discharge is detected, and the first switch is turned on for the period t2, thereby applying the main discharge pulse between the electrodes. Such an operation is repeated until the machining is completed.
- Processing is generally carried out by reducing energy in the order of roughing, intermediate finishing, finishing and super-finishing.
- the pulse width t2 of the main discharge pulse is the widest during rough machining, and gradually decreases with intermediate finishing and finishing.
- the main discharge pulse is not applied and the processing may be performed only with the preliminary discharge pulse.
- the main discharge pulse applied after the preliminary discharge pulse is turned on for a period t2 having the same pulse width regardless of the polarity when the preliminary discharge pulse is applied.
- the discharge at the time of applying the preliminary discharge pulse may also be considered to have a different discharge form. For example, when the workpiece functions as a cathode, it has a narrow diameter with a cathode spot and a high current density, and when it functions as an anode, it has a large diameter and a low current density.
- the main discharge pulse after application of the preliminary discharge pulse is unified into the positive polarity processing, it can be considered that the discharge characteristics at the time of applying the preliminary discharge pulse are dragged in the initial stage.
- the discharge current of the main discharge pulse is small, such as in finishing, the difference between the preliminary discharge current and the machining current (machining energy) is also reduced. Therefore, it can be considered that the influence of the discharge state during the preliminary discharge remains so much.
- the difference in the discharge characteristics during the preliminary discharge has an influence upon the application of the main discharge pulse, there is a problem that the optimum machining cannot be performed when the conventional machining method is applied.
- the discharge start voltage changes depending on the electrode material. That is, when the material of the electrode is different, it may be considered that the discharge start voltage is also different.
- the difference in the discharge start voltage appears as a difference in discharge delay time, which is a difference in time until discharge starts.
- the inter-electrode voltage is an important index for grasping the inter-electrode distance, but the inter-electrode distance cannot be maintained accurately if a difference depending on the electrode material occurs in the inter-electrode voltage. Therefore, it leads to deterioration of processing quality such as wire breakage and processing accuracy failure.
- the present invention has been made in view of the above, and an object of the present invention is to provide an electric discharge machining apparatus capable of performing optimum machining such as realizing high quality machining with high machining accuracy and the like.
- an electric discharge machining apparatus outputs a preliminary discharge pulse output by alternately switching polarities, and an output after detecting a discharge by the preliminary discharge pulse.
- the workpiece is a positive electrode and the machining electrode is a negative electrode of the preliminary discharge pulse.
- the current waveform shape of each main discharge pulse is set to be different from each other and output with respect to the main discharge pulse applied subsequently to the main discharge pulse.
- the current of the main discharge pulse that is subsequently applied according to the polarity during the preliminary discharge is changed.
- FIG. 1 is a diagram showing a schematic configuration of an electric discharge machining apparatus according to an embodiment of the present invention.
- FIG. 2 is a diagram illustrating an example of a switching signal waveform output from the control unit, and an inter-electrode voltage waveform and an inter-electrode current waveform at that time.
- FIG. 3 is a chart comparing the characteristics of positive polarity processing and reverse polarity processing.
- FIG. 4 is a circuit configuration diagram of the wire electric discharge machining apparatus described in Patent Document 1.
- FIG. 5 is a diagram showing switching signal waveforms described in Patent Document 1. In FIG.
- FIG. 1 is a diagram showing a schematic configuration of an electric discharge machining apparatus according to an embodiment of the present invention, and is a functional block diagram mainly showing a power supply unit.
- the electric discharge machining apparatus 1 includes a power supply unit and electric discharge machining unit 3, and a control unit 4.
- the power supply unit and the electric discharge machining unit 3 have a power supply unit, and this power supply unit includes a preliminary discharge power supply 5 (also referred to as a sub power supply) and a main discharge power supply 6 (also referred to as a main power supply).
- a preliminary discharge power source 5 (also referred to as a sub power source) and a main discharge power source 6 respectively transmit a preliminary discharge pulse and a main discharge pulse, which will be described later, between electrodes (a workpiece 11 and an electrode 12 that is a processing electrode) ( That is, it is applied between the electrodes). These timings are controlled by the control unit 4.
- the preliminary discharge power source 5 includes a first power source 7 that is a DC power source, a second power source 8 that is a DC power source, SW1 and SW2 that are switching elements such as FETs, and a diode D1. , D2, D3, D4 and current limiting resistors R1, R2.
- the + (plus) terminal of the first power supply 7 is connected to the anode of the diode D1, and the ⁇ (minus) terminal is connected to the + terminal of the second power supply 8.
- the cathode of the diode D1 is connected to the drain of the switching element SW1, and the source of the switching element SW1 is connected to the current limiting resistor R1.
- the current limiting resistor R2 is connected to the anode of the diode D2
- the cathode of the diode D2 is connected to the drain of the switching element SW2.
- the source of the switching element SW2 is connected to the negative terminal of the second power supply 8.
- the negative terminal of the second power source is connected to the anode of the diode D3, and the cathode side of the diode D3 is connected to the current limiting resistor R1.
- the current limiting resistor R2 and the anode of the diode D4 are connected, and the cathode of the diode D4 and the + terminal of the first power supply 7 are connected.
- connection point connecting the-terminal of the first power supply 7 and the + terminal of the second power supply is connected to the electrode 12.
- the end of the current limiting resistor R1 that is not connected to the switching element SW1 is connected to the workpiece 11, and the end of the current limiting resistor R2 that is not connected to the diode D2 is also connected to the workpiece. 11 is connected.
- the first power supply 7 applies a predischarge pulse A having a positive polarity to the workpiece 11 and the electrode 12 via the switching element SW1
- the second power supply 8 applies the workpiece 11 and the electrode via the switching element SW2. 12 is applied with a preliminary discharge pulse B having a reverse polarity.
- the voltage settings of the preliminary discharge pulse A and the preliminary discharge pulse B can be arbitrarily adjusted.
- the current limiting resistor R1 and the current limiting resistor R2 are currents that flow when the preliminary discharge pulse A and the preliminary discharge pulse B are applied, respectively, these current amounts are adjusted by designing them to different values. You can also
- the main discharge power source 6 includes a third power source 9 that is a DC power source, switching elements SW3 and SW4, and diodes D5 and D6.
- the drain of the switching element SW3 is connected to the + terminal of the third power supply 9.
- the source of the switching element SW3 is connected to the cathode of the diode D5, and this connection point is connected to the workpiece 11.
- the source of the switching element SW4 is connected to the negative terminal of the third power source.
- the drain of the switching element SW4 is connected to the anode of the diode D6, and this connection point is connected to the electrode 12.
- a host controller 32 including a machining parameter 30 and an operation identification processing unit 31 is provided outside the electric discharge machining apparatus 1.
- the machining parameter 30 includes information indicating a machining operation, a machining condition, and the like, and the operation identification processing unit 31 performs control information (hereinafter, “machining”) required for performing electrical discharge machining based on the information of the machining parameter 30.
- Information is identified and transmitted to the control unit 4.
- the control information includes, for example, information on which one of processing speed, surface roughness, electrode wear, straightness, etc. is important.
- the control unit 4 determines processing power to be applied between the workpiece 11 and the processing electrode 12 using the processing information output from the motion identification processing unit 31, and performs switching control of the switching elements SW1 to SW4.
- the pulse width (pulse application time), the pulse pause width (pulse pause time), and the mutual combination pattern in the pulse signal to be determined are determined.
- the switching elements SW1 to SW4 are controlled based on a switching signal output from the control unit 4, and a desired inter-electrode voltage and inter-electrode current between the workpiece 11 and the processing electrode 12 have arbitrary waveform timings. Supplied in.
- FIG. 2 is a diagram illustrating an example of a switching signal waveform output from the control unit 4, and an inter-electrode voltage waveform and an inter-electrode current waveform at that time. More specifically, FIGS. 4A to 4D show switching signals applied to the switching elements SW1 to SW4, respectively.
- the preliminary discharge pulse at this time is a positive preliminary discharge pulse in which the workpiece 11 is a positive electrode and the electrode 12 is a negative electrode, and is referred to as a preliminary discharge pulse A to be distinguished from a reverse polarity preliminary discharge pulse described later.
- the positive preliminary discharge pulse A appears as a voltage pulse between the electrodes.
- the preliminary discharge pulse A between times t0 and t1 is set so that the voltage value between the electrodes is V1.
- the switching element SW3 When the discharge is detected at time t1, the switching element SW3 is turned off and the switching element SW3 and the switching element SW4 are turned on at the same time.
- the discharge can be detected by, for example, providing a current detector (not shown) in the power supply unit and the electric discharge machining unit 3 and detecting the current accompanying the start of discharge.
- a current detector not shown
- current flows through the path of the third power source 9 ⁇ the switching element SW3 ⁇ the workpiece 11 ⁇ the electrode 12 ⁇ the switching element SW4 ⁇ the third power source 9, and the main discharge pulse is output between the electrodes.
- a main discharge pulse that is induced by the preliminary discharge pulse A and is applied subsequent to the preliminary discharge pulse A is referred to as a main discharge pulse A.
- the switching element SW3 is turned off at time t2 while the main discharge pulse A is being applied, the current flowing in the workpiece 11 and the electrode 12 due to the floating inductance component is the workpiece 11 ⁇ electrode 12 ⁇ switching element SW4 ⁇ diode D5. ⁇ Reflux through the path of the workpiece 11. Further, the switching element SW4 is also turned off immediately before the time t3, so that the current is regenerated to the power supply side in the path of the workpiece 11 ⁇ the electrode 12 ⁇ the diode D6 ⁇ the third power source 9 ⁇ the diode D5 ⁇ the workpiece 11.
- the main discharge pulse A is applied during the period T1.
- the switching element SW2 is turned on at time t4, which is separated from the time t3 by the suspension period S1.
- current flows through the path of the second power source 8 ⁇ electrode 12 ⁇ workpiece 11 ⁇ current limiting resistor R2 ⁇ diode D2 ⁇ switching element SW2 ⁇ second power source 8, and the preliminary discharge pulse B is output between the electrodes. Is done.
- the pre-discharge pulse B having a reverse polarity appears as a voltage pulse between the electrodes.
- the preliminary discharge pulse B between times t4 and t5 is set so that the voltage value between the electrodes is V2.
- V2 can be set independently of V1 described above, that is, generally different from V1.
- the switching element SW2 is turned off and the switching element SW3 and the switching element SW4 are turned on at the same time.
- a discharge is induced by the preliminary discharge pulse B, and a main discharge pulse applied subsequent to the preliminary discharge pulse B is referred to as a main discharge pulse B.
- the main discharge pulse B is applied during the period T2.
- the main discharge pulse B has no reflux period. Thereby, at time t6, the switching element SW3 and the switching element SW4 are simultaneously turned off. The current flowing between the poles is regenerated to the power source side through the path of the workpiece 11 ⁇ the electrode 12 ⁇ the diode D6 ⁇ the third power source 9 ⁇ the diode 5 ⁇ the workpiece 11 and between time t5 and t7 (period In T2), a substantially triangular wave shape is obtained as the interelectrode current waveform.
- the main discharge current due to the application of the main discharge pulse continues to flow for a while even when the switching elements SW3 and SW4 are turned off by the amount of time for current regeneration.
- the rest periods S1 and S2 are the control timings from the moment when the switching elements SW3 and SW4 are simultaneously turned off to stop the main discharge current until the next preliminary discharge pulse application. Indicates the time from the end of the main discharge current (that is, after it becomes zero) until the next preliminary discharge pulse is applied (see the period of S1 and S2 in the figure).
- the time from the end of the main discharge current (main discharge current A) by the main discharge pulse A to the application of the preliminary discharge pulse B is the rest time S1
- the main discharge current (main discharge current B) by the main discharge pulse B is defined as a rest period S2.
- the first power source 7 for generating the preliminary discharge pulse A and the second power source 8 for generating the preliminary discharge pulse B are independent. Therefore, the preliminary discharge pulse A has the voltage value V1 and the preliminary discharge pulse A. B is set to a voltage value V2.
- the main discharge pulse A is a reflux waveform and the main discharge pulse B is a triangular waveform.
- this shape and current peak value are arbitrary and are examples.
- FIG. 3 is a chart comparing the characteristics of positive polarity processing and reverse polarity processing.
- the meaning of “ ⁇ ” means superior to “ ⁇ ”, and conversely, the meaning of “ ⁇ ” means inferior to “ ⁇ ”.
- ⁇ means superior to “ ⁇ ”
- ⁇ means inferior to “ ⁇ ”.
- the preliminary discharge power source be processed only with positive polarity for high speed, but it is known that when water is used as a processing liquid, processing is performed only with a single polarity. Therefore, it is general to apply and adjust an AC waveform so that the average voltage between the electrodes becomes 0 V using a preliminary discharge power source having an auxiliary role in processing.
- the reason why the processing characteristics differ between positive polarity and reverse polarity is thought to be because the discharge spreads differently between the anode and the cathode. That is, it can be said that the difference in the processing density is caused by the difference in the current density.
- the main discharge pulse generally has a larger current value than the preliminary discharge pulse, and has a large influence on machining. That is, the effect of positive polarity processing mainly appears as the whole processing.
- the effect of the preliminary discharge current is relative in the case of machining with a small machining energy (determined by the charge amount, current peak value, applied voltage, current pulse width, etc.) of the main discharge pulse (for example, finishing machining or fine wire machining) Become bigger.
- the above-mentioned processing characteristics such as processing speed, straightness, electrode wear (wire breakage), and surface roughness change according to the application state of the preliminary discharge pulse, and in the case of positive polarity, as described above, the processing speed and electrode wear ( Wire breakage) and straightness, and in the case of reverse polarity, it works to improve surface roughness.
- the current of the main discharge pulse having a positive polarity is also affected by the characteristics of the preliminary discharge pulse immediately before that.
- the shape (current density) of the electrode surface determined by the preliminary discharge is directly connected to the main discharge pulse.
- the preliminary discharge itself may be treated as the same characteristic as the main discharge pulse.
- the shape of the electrode surface at the reverse polarity changes to the shape of the electrode surface at the positive polarity.
- the initial application of the main discharge pulse B may be considered to have the reverse polarity characteristics of the preliminary discharge pulse B.
- the discharge is independent once at a time, it is easily affected by the previous discharge. If the positive polarity pre-discharge pulse A and the main discharge pulse A are applied before the application of the pre-discharge pulse B having the reverse polarity, the discharge is likely to be induced at the same location when the subsequent rest time S1 is not sufficient, Furthermore, since the shape of the electrode surface in the case of positive polarity is dragged, it is impossible to take advantage of the nature of the reverse polarity.
- the positive discharge can be obtained by changing the preliminary discharge pulse B and the parameters before and after that.
- the ability of sexual processing can be fully utilized.
- the discharge current discharged by the preliminary discharge pulse B and the discharge current discharged by the preliminary discharge pulse A are designed to reduce the discharge current discharged by the preliminary discharge pulse B.
- the current limiting resistor R2 may be larger than the current limiting resistor R1, or the power supply voltage V1 of the first power supply 7 may be set higher than the power supply voltage V2 of the second power supply 8.
- the initial discharge of the main discharge pulse B is easily affected by reverse polarity. Therefore, in order to take advantage of the positive polarity characteristics, it is desirable to set the discharge energy to be larger, for example, by setting the current peak value larger than the main discharge pulse A and increasing the charge amount. That is, with respect to the main discharge pulse A and the main discharge pulse B, for example, the current peak value of the main discharge pulse B is made larger and the current waveform shapes are different from each other. Alternatively, if the input energy can be earned by applying the main discharge pulse A, the energy of the main discharge pulse B affected by the reverse polarity may be extremely reduced.
- the discharge current discharged by the preliminary discharge pulse B is designed to be larger than the discharge current discharged by the preliminary discharge pulse A.
- the current limiting resistor R2 may be smaller than the current limiting resistor R1, or the power supply voltage V1 of the first power supply 7 may be set lower than the power supply voltage V2 of the second power supply 8.
- the discharge start voltage described later it is necessary to consider that it is influenced by the discharge start voltage described later as described above.
- control is an example, and since each characteristic varies depending on the downtime and the processing material, what kind of control is desirable depends on circumstances.
- the application forms of the main discharge pulses applied following each preliminary discharge pulse are different. By doing so, better processing can be performed.
- the machining current shape is optimized according to the discharge characteristics, and high precision machining is performed. It can be carried out.
- in order to change the current waveform shape according to the polarity of the preliminary discharge pulse for example, when the charge amount is changed and the input energy is changed according to the discharge characteristics, or when the current peak value is changed. is there.
- the characteristics of positive polarity and reverse polarity can be reflected more remarkably, and optimum processing can be performed.
- pause time from turning off the main discharge pulse to applying the preliminary discharge pulse appropriate, it is possible to better draw out the positive polarity and reverse polarity characteristics of the preliminary discharge pulse. That is, high-accuracy machining can be performed by setting the pause time according to the discharge characteristics, such as setting the pause times S1 and S2 to different values.
- the parameters to be changed according to the discharge characteristics are independent of each other, and need not be combined to satisfy all of them.
- the resting time S1 may be set shorter than the resting time S2 (the influence of the positive polarity is great) while the current limiting resistance R2 is set smaller than the current limiting resistance R1 (the influence of reverse polarity is great).
- the original purpose of the preliminary discharge pulse is to induce discharge.
- the characteristics of positive polarity and reverse polarity are characteristics of the discharge current that flows during processing, that is, after the start of discharge, and are different from the phenomenon of dielectric breakdown that triggers discharge. Since the characteristics of the cathode and the anode are different at the start of discharge, an optimum value exists.
- the discharge gap varies depending on the wire and processing behavior, and fluctuates in the order of several tens to several hundreds of ms. You can.
- the discharge start voltage differs depending on the material, if the voltages V1 and V2 of the preliminary discharge pulse A and the preliminary discharge pulse B are the same, the time until discharge start (discharge delay time) will be different.
- the case of a positive polarity (preliminary discharge pulse A) in which the wire electrode is a substance that is easily discharged and acts as a cathode will be described with reference to FIG.
- V1 V2
- the time (t1-t0) from when the preliminary discharge pulse A is applied to when the discharge is detected and stopped (t1-t0) tends to be shorter than the application time (t5-t4) of the preliminary discharge pulse B.
- the application time of the preliminary discharge pulse B is unnecessarily long. This leads to a decrease in the discharge frequency, so that the machining speed is decreased.
- V2> V1 may be set so as to shorten the discharge delay time of the preliminary discharge pulse B.
- the machining gap is stabilized, the discharge efficiency is improved, and the machining speed can be improved.
- V1 and V2 differs depending on the material, it cannot be generally stated.
- the wire electrode since the wire electrode can be selected relatively freely for the workpiece, the wire electrode has a good discharge characteristic (low discharge start voltage). It can be said that it is better to design V2> V1 as described above.
- the material having a low discharge start voltage is, for example, Zn.
- FIG. 4 is a circuit configuration diagram of the wire electric discharge machining apparatus described in Patent Document 1
- FIG. 5 is a diagram illustrating a switching signal waveform described in Patent Document 1.
- the conventional wire electric discharge machining apparatus includes an electrode 101, a workpiece 102, a first switch 103, a first DC power supply 104, a current-carrying chip 105, a surge voltage absorption circuit 106, a diode 107, 2 switch 108, second DC power supply 109, resistor 110, capacitor 112, inductance 113, resistor 114, control circuit 115, drive circuits 116 and 117, third switch 120, third DC power supply 121, resistor 122, A driving circuit 123, diodes 124, 125, 126, and signal lines 127, 128 are provided.
- a second DC power supply 109 and a third DC power supply 121 are preliminary discharge power supplies for applying preliminary discharge pulses
- a first DC power supply 104 is a main discharge power supply for applying main discharge pulses.
- the second DC power supply 109 and the third DC power supply 121 are alternately applied to prevent electrical corrosion, thereby changing the machining polarity and performing preliminary discharge. Generate a pulse.
- the main discharge pulse that greatly contributes to machining is generated under positive polarity machining with the workpiece 102 as the positive electrode and the electrode 101 as the negative electrode.
- the main discharge pulse is stopped to regenerate the current flowing in the floating reactor, and at the same time, a pause time is provided in which the gap is a sinking time.
- a current flows through the third DC power supply 121-the workpiece 102-the electrode 101-the diode 126-the switch 120-the third DC power supply 121 loop, and a spare having a polarity different from the previous one.
- a discharge pulse is applied to the polarity.
- the switch 120 is turned on after the period t1 when the discharge is detected, and the switch 103 is turned on for the period t2, thereby applying the main discharge pulse between the electrodes.
- the main discharge pulse applied after the preliminary discharge pulse is turned on only for a period t2 having the same pulse width regardless of the polarity.
- the discharge at the time of applying the preliminary discharge pulse may also be considered to have a different discharge form.
- the main discharge pulse after application of the preliminary discharge pulse is unified into the positive polarity machining, it can be considered that the discharge characteristics at the time of applying the preliminary discharge pulse are dragged in the initial stage.
- the main discharge pulse is applied in the same way regardless of the polarity at the time of preliminary discharge, so high-precision machining that fully utilizes the ability of positive polarity machining or reverse polarity machining is performed. There is a problem that it is difficult.
- the present embodiment solves such problems of the prior art.
- the electric discharge machining apparatus can perform high-precision and high-function machining by selecting an optimum method as necessary, such as high speed, low wear, high surface accuracy, and high straightness accuracy. It is useful as a possible invention.
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Abstract
Description
3 電源部および放電加工部
4 制御部
7 第1の直流電源
8 第2の直流電源
9 第3の直流電源
11 被加工物
12 加工用電極
30 加工パラメータ
31 動作識別処理部
32 上位コントローラ
101 電極
102 被加工物
103 第1のスイッチ
104 第1の直流電源
105 通電チップ
106 サージ電圧吸収回路
107,124,125,126 ダイオード
108 第2のスイッチ
109 第2の直流電源
110,114,122 抵抗
112 コンデンサ
113 インダクタンス
115 制御回路
116,117,123 駆動回路
120 第3のスイッチ
121 第3の直流電源
127,128 信号線
逆極性として働くのは予備放電パルスBのみであり、予備放電パルスA、主放電パルスA、主放電パルスBは正極性であるから、予備放電パルスB及びその前後のパラメータを変化させることで正極性加工の能力を十分に生かすことができる。(1)予備放電パルスBにより放電する放電電流と予備放電パルスAにより放電する放電電流とでは、予備放電パルスBにより放電する放電電流を小さくするように設計する。例えば、電流制限抵抗R2を電流制限抵抗R1より大きくしてもよいし、第1の電源7の電源電圧V1を第2の電源8の電源電圧V2より高く設定しても良い。ただし、電源電圧を高くする場合は後述の放電開始電圧の影響も考慮する必要がある。(2)主放電パルスBの放電初期は逆極性の影響を受けやすい。そのため正極性の特性を生かすためには主放電パルスAよりも電流ピーク値を大きく、電荷量を大きくするなど放電エネルギーを大きく設定することが望ましい。すなわち、主放電パルスAと主放電パルスBとに対して、例えば主放電パルスBの電流ピーク値をより大きくし、電流波形形状を相互に異なるものとしている。あるいは、投入エネルギーは主放電パルスAの印加により稼げるとすれば、逆極性の影響を受けている主放電パルスBは極端にエネルギーを小さくしてしまってもよい。ただし、これは加工材質やワイヤ径、板厚など加工環境に依存するためどのように設計するかは一義的には決められない。(3)休止時間S1を小さくすることで正極性加工の主放電パルスAの影響を予備放電パルスBに及ぼすことができる。つまり逆極性の特性を小さくすることができる。なお、休止時間の定量的な長さもまた加工環境に応じて変化するため一義的に決められるものではないが、少なくとも休止時間S2よりも休止時間S1の方が短く設定することが望ましい。
上記とは逆に予備放電パルスA及びその後の主放電パルスAの寄与が大きくなるようにパラメータを変化させることで逆極性加工の能力を十分に生かすことができる。(1)予備放電パルスBにより放電する放電電流は予備放電パルスAにより放電する放電電流よりも大きく設計する。例えば、電流制限抵抗R2を電流制限抵抗R1より小さくしてもよいし、第1の電源7の電源電圧V1を第2の電源8の電源電圧V2より低く設定しても良い。ただし、前述と同様に後述の放電開始電圧の影響を受けることも考慮する必要がある。(2)主放電パルスBの放電初期は逆極性の影響を受けていることから主放電パルスBの電流ピーク値を低くすることが望ましい。さらに、加工エネルギーを確保したい場合には還流波形を用いることで放電初期の逆極性の電極表面の形状に近い状況のまま加工エネルギーを増やすことも可能となる。(3)正極性加工とは逆に休止時間S1は休止時間S2よりも長く設定することが望ましい。これにより、正極性の主放電パルスが逆極性の予備放電パルスBに及ぼす影響を抑制することができる。
図4は、特許文献1に記載されているワイヤ放電加工装置の回路構成図であり、図5は、特許文献1に記載されているスイッチング信号波形を示す図である。図4に示すように、従来のワイヤ放電加工装置は、電極101、被加工物102、第1のスイッチ103、第1の直流電源104、通電チップ105、サージ電圧吸収回路106、ダイオード107、第2のスイッチ108、第2の直流電源109、抵抗110、コンデンサ112、インダクタンス113、抵抗114、制御回路115、駆動回路116、117、第3のスイッチ120、第3の直流電源121、抵抗122、駆動回路123、ダイオード124、125、126、および信号線127、128、を備えている。
Claims (6)
- 交互に極性を切り替えて出力される予備放電パルスと、この予備放電パルスによる放電を検出した後に続いて出力される主放電パルスとを、加工用電極と被加工物との間に印加して放電加工を行う放電加工装置において、
前記被加工物を正極、前記加工用電極を負極として出力された正極性の予備放電パルスに続いて印加される主放電パルスと、
前記被加工物を負極、前記加工用電極を正極として出力された逆極性の予備放電パルスに続いて印加される主放電パルスとに対して、
前記各主放電パルスの電流波形形状を相互に異なるように設定して出力することを特徴とする放電加工装置。 - 前記各主放電パルスの電流波形形状は、出力される電荷量をそれぞれ異ならせることにより、相互に異なるように設定したことを特徴とする請求項1に記載の放電加工装置。
- 前記各主放電パルスの電流波形形状は、電流ピーク値をそれぞれ異ならせることにより、相互に異なるように設定したことを特徴とする請求項1に記載の放電加工装置。
- 交互に極性を切り替えて出力される予備放電パルスと、この予備放電パルスによる放電を検出した後に続いて出力される主放電パルスとを、加工用電極と被加工物との間に印加して放電加工を行う放電加工装置において、
前記主放電パルスの印加後に休止時間を設けて加工を行う場合に、
前記被加工物を正極、前記加工用電極を負極として出力された正極性の予備放電パルスの印加後に設けられた休止時間と、
前記被加工物を負極、前記加工用電極を正極として出力された逆極性の予備放電パルスの印加後に設けられた休止時間とを、
相互に異なるように設定したことを特徴とする放電加工装置。 - 交互に極性を切り替えて出力される予備放電パルスと、この予備放電パルスによる放電を検出した後に続いて出力される主放電パルスとを、加工用電極と被加工物との間に印加して放電加工を行う放電加工装置において、
前記被加工物を正極、前記加工用電極を負極として出力された正極性の予備放電パルスの印加電圧と、
前記被加工物を負極、前記加工用電極を正極として出力された逆極性の予備放電パルスの印加電圧とでは、
前記逆極性の予備放電パルスの印加電圧のほうがより大きくなるように設定されていることを特徴とする放電加工装置。 - 交互に極性を切り替えて出力される予備放電パルスと、この予備放電パルスによる放電を検出した後に続いて出力される主放電パルスとを、加工用電極と被加工物との間に印加して放電加工を行う放電加工装置において、
前記被加工物を正極、前記加工用電極を負極として出力された正極性の予備放電パルスによる放電電流と、
前記被加工物を負極、前記加工用電極を正極として出力された逆極性の予備放電パルスによる放電電流とを、
相互に異なるように設定したことを特徴とする放電加工装置。
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US12/864,195 US20100294743A1 (en) | 2008-01-31 | 2008-01-31 | Electric discharge device |
CN2008801260051A CN101932402B (zh) | 2008-01-31 | 2008-01-31 | 放电加工装置 |
JP2009551377A JP5220036B2 (ja) | 2008-01-31 | 2008-01-31 | 放電加工装置 |
DE200811003599 DE112008003599B4 (de) | 2008-01-31 | 2008-01-31 | Entladungsgerät |
PCT/JP2008/051554 WO2009096027A1 (ja) | 2008-01-31 | 2008-01-31 | 放電加工装置 |
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DE112011104963T5 (de) * | 2011-02-25 | 2013-11-28 | Mitsubishi Electric Corporation | Energieversorgungsvorrichtung für eine Funkenerosionsmaschineund ein Steuerverfahren dafür |
JP5389994B1 (ja) * | 2012-08-08 | 2014-01-15 | 株式会社ソディック | 放電加工機 |
US9446465B2 (en) * | 2012-10-30 | 2016-09-20 | Mitsubishi Electric Corporation | Wire electric-discharge machining apparatus |
JP6514163B2 (ja) | 2016-09-01 | 2019-05-15 | ファナック株式会社 | ワイヤ放電加工機 |
JP6770041B2 (ja) * | 2018-10-23 | 2020-10-14 | ファナック株式会社 | ワイヤ放電加工機および放電加工方法 |
CN112930238B (zh) * | 2018-10-31 | 2024-03-29 | 株式会社牧野铣床制作所 | 放电加工机的电源装置 |
FR3091409B1 (fr) * | 2018-12-31 | 2020-12-25 | Adm28 S Ar L | Dispositif de décharge électrique impulsionnelle |
DE102022115454B4 (de) | 2022-06-21 | 2023-12-28 | VOLAS GmbH | Vorrichtung und Verfahren zur Texturierung und/oder Beschichtung einer Oberfläche eines Bauteils |
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JP6972443B1 (ja) * | 2021-03-03 | 2021-11-24 | 三菱電機株式会社 | ワイヤ放電加工装置、形状寸法補償器、ワイヤ放電加工方法、学習装置、および推論装置 |
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