CN109570658B - Capacitance-induced micro electric spark machining pulse power supply - Google Patents
Capacitance-induced micro electric spark machining pulse power supply Download PDFInfo
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- 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
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Abstract
The invention discloses a capacitance-induced micro electric spark machining pulse power supply, which comprises: the device comprises an inter-pulse capacitance equal-energy deionization module, a capacitance induced high-voltage ignition module, a voltage detection module, a non-contact current detection module, a high-voltage ignition-pulse current selector and a capacitance induced micro electric spark discharge control module; the capacitance-induced micro electric spark discharge control module correspondingly controls the inter-pulse capacitance equal-energy deionization module and the capacitance-induced high-voltage ignition module according to the processing pulse signals, so that the inter-pulse deionization and pulse width high-voltage ignition processes are realized. The invention combines the capacitance-induced micro-spark discharge process with the high-efficiency processing pulse power supply technology, and unifies the equal energy mode with good discharge consistency with the equal pulse width mode with higher discharge frequency and processing speed. The capacitance induction type high-efficiency pulse power supply provided by the invention is used for carrying out micro electric spark machining, so that the discharge rate, the discharge consistency and the energy utilization rate are effectively improved, and the short-time high-current-density micro spark discharge process is realized.
Description
Technical Field
The invention relates to the technical field of electric spark machining, in particular to a capacitance-induced micro electric spark machining pulse power supply and a working method.
Background
With the continuous emergence of metal alloy materials with excellent performance, precise micro-miniature metal alloy parts are widely applied to high-end equipment. In these devices, the microstructure (micro-hole and micro-three-dimensional structure) parts with specific shape and size directly determine the quality of the whole device, and the characteristic size of these microstructures is usually tens to hundreds of micrometers, such as micro-jet holes on high-end diesel engine oil nozzles, chemical fiber spinneret plates, printer inkjet heads, micro-radiators, cell filters, biochip micro-molds, and the like. Therefore, it is an important development direction in the modern manufacturing field to fine process high-performance alloy materials.
Micro Electrical Discharge Machining (EDM) is a special Electrical Machining technology which is low in Machining cost and easy to realize, and has unique technological advantages in Micro Machining: the non-contact processing mode without macroscopic mechanical cutting force can process a high-hardness workpiece by using a low-hardness tool electrode; can be used for processing various conductive materials such as metal, alloy and the like, semiconductor materials such as silicon and the like, even ceramic materials, sintered diamond materials and the like. Rough machining, semi-finish machining and finish machining can be realized only by adjusting the discharge energy of the pulse power supply and the machining gap between electrodes, so that higher machining precision is obtained while machining efficiency is guaranteed. Therefore, the micro electric discharge machining technology becomes one of the common effective machining methods in the field of special machining, and has obvious advantages for high-precision and high-efficiency machining of parts with microstructures. The short-time high-current-density micro-spark discharge is adopted, the action time is extremely short, the gasification corrosion removal processing is mainly adopted, the thickness of an altered layer can be reduced, the surface quality is improved, the internal stress is reduced, the generation of micro cracks is avoided, the processing efficiency is improved, and the surface processing quality is improved.
In micro electric discharge machining, due to the problems of small discharge area, low discharge rate, unstable discharge state, rapid electrode loss and the like, the machining efficiency and the surface quality are reduced. The pulse power supply technology is one of core technologies in electric spark machining, and the performance of the pulse power supply technology directly influences the machining efficiency, the machining quality and the machining stability of a machine tool. The traditional pulse power supply technology is mature and widely applied to domestic electric spark machine tools, but when the pulse power supply technology is applied to micro-structure machining, the pulse discharge rate and the machining precision are reduced, and the surface roughness is deteriorated. How to improve the discharge rate and the discharge consistency is still one of the important problems to be solved at present.
In the current electric spark discharge machining research, most of attention is paid to the whole states of ionization, avalanche breakdown, discharge channel formation, material ejection erosion, deionization and the like of a secondary electrode-electrode medium, so that ions between channels do directional motion under the action of an analysis pulse power supply, electric energy is converted into kinetic energy, the kinetic energy is converted into heat energy through collision, and then high temperature is generated on the surfaces of a positive electrode and a negative electrode at two ends of the channel, so that metal materials are melted to boil and are evaporated and ejected. In the process, only the problem of converting electric energy into kinetic energy and the like is concerned, and the influence of electromagnetic field energy caused by transient electric field energy density change on the discharge process, particularly the influence on the ionization and breakdown process of an interpolar medium, is neglected. The high-voltage ignition mode improves the discharge rate to a certain extent, but the applied ignition energy and the discharge delay are uncontrollable, and the discharge delay is long under most conditions and occupies about 40-50% of the pulse time, so that the discharge rate is low and the discharge is uneven, which is also a common problem in the existing micro electric discharge machining.
Therefore, how to ensure the micro spark discharge with high discharge rate, high discharge consistency, short discharge delay and short time and high current density is a key technical problem to be solved in the design of the micro electric spark machining pulse power supply.
Disclosure of Invention
In order to solve at least one technical problem in the prior art, the invention provides a capacitance-induced micro electric discharge machining pulse power supply and a working method.
One embodiment of the present invention provides a capacitance-induced micro electro-discharge machining pulse power supply, including:
the device comprises an inter-pulse capacitance equal-energy deionization module (1), a capacitance induction high-voltage ignition module (2), a voltage detection module (3), a non-contact current detection module (4), a high-voltage ignition-pulse current selector (5) and a capacitance induction micro electric spark discharge control module (6);
the first end of the high-voltage ignition-pulse current selector (5) is connected with the high-voltage ignition output end (H) of the capacitance induction high-voltage ignition module (2), and the second end is connected with the processing pulse current (I)p0) The output end (M) is connected with a tool electrode (7);
the workpiece electrode (8) is connected with the output end (N) of the capacitance induced high-voltage ignition module (2), and a connecting wire penetrates through the non-contact current detection module (4);
the first end of the inter-pulse capacitance equal-energy deionization module (1) is connected with the output end (M) of the high-voltage ignition-pulse current selector (5), and the second end of the inter-pulse capacitance equal-energy deionization module is connected with the output end (N) of the capacitance induction high-voltage ignition module (2);
working liquid is filled between the tool electrode (7) and the workpiece electrode (8); the first end of the voltage detection module (3) is connected with the tool electrode (7), and the second end is connected with the workpiece electrode (8);
the capacitance-induced micro electric spark discharge control module (6) is connected with the inter-pulse capacitance equal-energy deionization module (1), the capacitance-induced high-voltage ignition module (2), the voltage detection module (3) and the non-contact current detection module (4).
Optionally, the inter-pulse capacitance isoenergetic deionization module (1) comprises:
first charging power supply (V)cc1) A first capacitor (C)de) A first switch (S)1) A second switch (S)2) And a third switch (S)3) And a fourth switch (S)4)；
The first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Forming an H bridge.
Optionally, the capacitive induced high voltage ignition module (2) comprises:
second charging power supply (V)ccH) A second capacitor (C)ig) And a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And an eighth switch (S)8)；
The fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Forming an H bridge.
Optionally, the first charging power supply (V)cc1) Is several tens of volts, the first capacitance (C)de) Hundreds of picofarads; the second charging power supply (V)ccH) At hundred ten volts, the second capacitance (C)ig) Thousands of picofarads; the first charging power supply (V)cc1) And the second charging power supply (V)ccH) Not common to ground.
Optionally, the first switch (S)1) A second switch (S)2) A third switch (S3), a fourth switch (S4), a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And eighth switchOff (S)8) Is a MOS tube or a triode or an insulated gate bipolar transistor IGBT or controllable silicon.
Another embodiment of the present invention provides a working method of the capacitance-induced micro electrical discharge machining pulse power supply, including:
the capacitance-induced micro electric spark discharge control module (6) performs servo control of short circuit, open circuit and machining according to output signals of the voltage detection module (3) and the non-contact current detection module (4);
the capacitance-induced micro electric spark discharge control module (6) is used for controlling the discharge according to the machining pulse current (I)p0) Pulse width T ofonAnd the interpulse ToffThe pulse-to-pulse deionization control is carried out on the pulse-to-pulse capacitance equal-energy deionization module (1), and the pulse width high-voltage ignition process control is carried out on the capacitance induction high-voltage ignition module (2).
Alternatively, [0, t ]5]For machining pulsed currents (I)p0) Inter-pulse T of one pulse periodoff，[t5，t11]For machining pulsed currents (I)p0) Pulse width T of one pulse periodon；
At [ t ]0，t2]Charging the inter-pulse capacitance equal-energy deionization module (1) for a period of time until t1Steady state voltage after the moment is Ude；
At [ t ]2，t5]Connecting the inter-pulse capacitance equal-energy deionization module (1) between the tool electrode (7) and the workpiece electrode (8) in a negative polarity mode, wherein the potential of the workpiece electrode (8) is zero, the potential of the tool electrode (7) is negative, discharging is carried out on the workpiece electrode until t3Steady state voltage after the moment is-UrAt the interval of the pulse ToffThe process of equal energy deionization in the machining gap is completed in a period of time, and | -Ur|<|Ude|；
At [ t ]0，t5]Charging the capacitive induction high voltage ignition module (2) for a period of time up to t4Steady state voltage after the moment is Uig，UigA high voltage ignition voltage;
at [ t ]5，t10]The capacitance induction high-voltage ignition module (2) is connected between the tool electrode (7) and the workpiece electrode (8) in a positive polarity mode in a time period, and is discharged to t7At the moment, the interelectrode voltage quickly reaches the breakdown critical voltage UD(ii) a After [ t ]7，t8]The time period is discharge delay; [ t ] of8，t9]The interelectrode medium is broken down in the period to form a plasma discharge channel, and meanwhile, the capacitance induced high-voltage ignition module (2) is continuously discharged until t9Reach steady state at all times, namely reach interpolar maintenance voltage UT(ii) a T formed in the plasma discharge channel8，t9]During the period, a low-voltage processing pulse current (I) is switched onp0) Performing electric discharge machining until t11Pulse width T of time machining pulseonFinishing the discharge machining process in one pulse period; and | Ude|<|UT|<|UD|<|Uig|。
Optionally, the inter-pulse capacitance isoenergetic deionization module (1) comprises: first charging power supply (V)cc1) A first capacitor (C)de) A first switch (S)1) A second switch (S)2) And a third switch (S)3) And a fourth switch (S)4) (ii) a The first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Forming an H bridge;
the working process of the inter-pulse capacitance equal-energy deionization module (1) comprises the following steps:
at [ t ]0，t2]Time period, the first switch (S)1) And a fourth switch (S)4) Open, the second switch (S)2) And the third switch (S)3) Closed, charging current (I)c_de) By the first charging power supply (V)cc1) Flows out through the third switch (S)3) The first capacitor (C)de) And said second switch (S)2) Flowing into the ground (Gnd)1) (ii) a The first capacitor (C)de) Has a charging steady-state voltage of Ude，Ude≈Vcc1；
At [ t ]2，t5]Time period, the first switch (S)1) And the fourth switch (S)4) Closed, the second switch (S)2) And the third switch (S)3) Disconnecting the workpiece electrode (8) and the tool electrode (7) and discharging the inter-pulse capacitance isoenergetic deionization module (1), wherein the output end (N) is a positive end and is connected with the workpiece electrode (8), and the output end (M) is a negative end;
at [ t ]5，t6]The time period and t6T to the next pulse period0Time period, the first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Are all disconnected.
Optionally, the capacitive induced high voltage ignition module (2) comprises: second charging power supply (V)ccH) A second capacitor (C)ig) And a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And an eighth switch (S)8) (ii) a The fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Forming an H bridge;
the working process of the capacitance induction high-voltage ignition module (2) comprises the following steps:
at [ t ]0，t5]Time period, the fifth switch (S)5) And the eighth switch (S)8) Open, the sixth switch (S)6) And the seventh switch (S)7) Closed, charging current (I)c_ig) By the second charging power supply (V)ccH) Flows out through the sixth switch (S)6) The second capacitor (C)ig) And the seventh switch (S)7) Flowing into the ground (Gnd)2) (ii) a The second capacitance (C)ig) Has a charging steady-state voltage of Uig，Uig≈VccH；
At [ t ]5，t10]Time period, the fifth switch (S)5) And the eighth switch (S)8) Closed, the sixth switch (S)6) And the seventh switch (S)7) Disconnected, the high-voltage ignition output end (H) is the positive end and is connected with the groundThe output end (N) of the tool electrode (7) is the negative end and is connected with the workpiece electrode (8) to discharge the capacitance induced high-voltage ignition module (2);
at [ t ]10，t11]The time period and t11T to the next pulse period0Time period, the fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Are all disconnected.
The invention has the technical effects that the capacitance-induced micro-spark discharge process is combined with the high-efficiency processing pulse power supply technology, and the equal energy mode with good discharge consistency is unified with the equal pulse width mode with higher discharge frequency and processing speed. The capacitance induction type high-efficiency pulse power supply is utilized to carry out micro electric spark machining, so that the discharge rate, the discharge consistency and the energy utilization rate can be effectively improved.
In addition, the invention can also shorten the breakdown delay, realize the short-time high-current-density micro spark discharge process, and effectively improve the processing efficiency, the surface quality and the processing stability while finishing the high-precision and high-quality micro electric spark processing.
The invention combines the characteristic of small stray capacitance between poles in micro-electric machining, fixes the initial ignition state to a negative voltage with a small absolute value (the potential of a workpiece is zero potential, the potential of a tool is negative at the moment, the potential is called as negative polarity, and is opposite to the processing), and in the initial ignition state, a large induced capacitor full of energy is connected between poles in a positive polarity mode in a very short time, and sudden electric field energy and electromagnetic field energy caused by the sudden change of the electric field are applied to the poles to promote the medium between the poles to be quickly and greatly ionized to generate avalanche breakdown, thereby greatly shortening the discharge delay time, simultaneously improving the discharge current density, and realizing the capacitance induced micro-spark discharge process with fixed initial ignition state, controllable ignition energy, short discharge delay and high discharge rate. The capacitance induction type micro spark discharge process is combined with a single pulse power supply technology with small and controllable pulse energy and high discharge rate, so that the processing efficiency and the surface quality are improved.
Drawings
FIG. 1 is a schematic diagram of a capacitive-induced micro electro-discharge machining pulse power supply according to an embodiment of the present invention;
FIGS. 2(a), 2(b), and 2(c) are schematic diagrams of capacitance-induced micro spark discharge waveforms according to an embodiment of the present invention;
FIGS. 3(a) and 3(b) are schematic diagrams of an inter-pulse deionization process according to an embodiment of the present invention;
fig. 4(a) and 4(b) are schematic diagrams of a high pressure ignition process according to one embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a capacitance-induced micro electro-discharge machining pulse power supply according to an embodiment of the present invention. As shown in fig. 1, the pulse power supply includes:
the device comprises an inter-pulse capacitance equal-energy deionization module 1, a capacitance induced high-voltage ignition module 2, a voltage detection module 3, a non-contact current detection module 4, a high-voltage ignition-pulse current selector 5 and a capacitance induced micro electric spark discharge control module 6;
the first end of the high-voltage ignition-pulse current selector 5 is connected with the high-voltage ignition output end H of the capacitance induction high-voltage ignition module 2, and the second end is connected with the processing pulse current Ip0The output end M is connected with a tool electrode 7;
the workpiece electrode 8 is connected with the output end N of the capacitance induced high-voltage ignition module 2, and a connecting wire penetrates through the non-contact current detection module 4;
the first end of the inter-pulse capacitance equal-energy deionization module 1 is connected with the output end M of the high-voltage ignition-pulse current selector 5, and the second end is connected with the output end N of the capacitance induced high-voltage ignition module 2;
working liquid is filled between the tool electrode 7 and the workpiece electrode 8; the first end of the voltage detection module 3 is connected with the tool electrode 7, and the second end is connected with the workpiece electrode 8;
the capacitance-induced micro electric spark discharge control module 6 is connected with the inter-pulse capacitance energy deionization module 1, the capacitance-induced high-voltage ignition module 2, the voltage detection module 3 and the non-contact current detection module 4.
On one hand, the capacitance-induced micro electric spark discharge control module 6 of the embodiment of the invention is based on the voltage detection module 3 and the current detection module CT 14, performing short circuit, open circuit and normal processing servo control, and correspondingly controlling the inter-pulse capacitive energy deionization module 1 and the capacitive induction high-voltage ignition module 2 according to the pulse width and the inter-pulse time sequence of the processing signal to realize the inter-pulse deionization and pulse width high-voltage ignition process.
The embodiment of the invention combines the capacitance induction type micro spark discharge process with the high-efficiency processing pulse power supply technology, and unifies the equal energy mode with good discharge consistency with the equal pulse width mode with higher discharge frequency and processing speed. The capacitance induction type high-efficiency pulse power supply is utilized to carry out micro electric spark machining, so that the discharge rate, the discharge consistency and the energy utilization rate can be effectively improved.
Specifically, as shown in fig. 3, the inter-pulse capacitance equivalent energy deionization module 1 includes:
first charging source Vcc1A first capacitor CdeA first switch S1A second switch S2And a third switch S3And a fourth switch S4；
First switch S1A second switch S2And a third switch S3And a fourth switch S4Forming an H bridge.
Specifically, as shown in fig. 4, the capacitance-induced high-voltage ignition module 2 includes:
second charging source VccHA second capacitor CigThe fifth switch S5And a sixth switch S6Seventh switch S7And an eighth switch S8；
Fifth switch S5And a sixth switch S6Seventh switch S7And an eighth switch S8Forming an H bridge.
In practical application, the first charging power supply Vcc1Is tens of volts, a first capacitor CdeHundreds of picofarads;second charging source VccHA hundred and ten volts, a second capacitor CigThousands of picofarads; first charging source Vcc1And a second charging power supply VccHNot common to ground.
Optionally, a first switch S1A second switch S2A third switch S3, a fourth switch S4, and a fifth switch S5And a sixth switch S6Seventh switch S7And an eighth switch S8Is a MOS tube or a triode or an insulated gate bipolar transistor IGBT or controllable silicon.
The operation method of the capacitance-induced WeChat electric discharge machining pulse power supply will be described below with reference to FIGS. 2, 3, and 4. In one embodiment of the invention, the method comprises:
the capacitance-induced micro electric spark discharge control module 6 detects the module 3 and the non-contact current detection module (CT) according to the voltage1)4, performing servo control on short circuit, open circuit and processing on the output signal;
the capacitance-induced micro electric spark discharge control module 6 controls the discharge according to the machining pulse current Ip0Pulse width T ofonAnd the interpulse ToffThe inter-pulse deionization control is carried out on the inter-pulse capacitance equal-energy deionization module 1, and the pulse width high-voltage ignition process control is carried out on the capacitance induction high-voltage ignition module 2.
Specifically, in fig. 2(a), 2(b) and 2(c), [0, t [ ]5]For machining pulse currents Ip0Inter-pulse T of one pulse periodoff，[t5，t11]For machining pulse currents Ip0Pulse width T of one pulse periodon；
At [ t ]0，t2]Charging the inter-pulse capacitance equal-energy deionization module 1 to t1Steady state voltage after the moment is Ude；
At [ t ]2，t5]Connecting the inter-pulse capacitance equal-energy deionization module 1 between the tool electrode 7 and the workpiece electrode 8 in a negative polarity mode, discharging the workpiece electrode 8 when the potential of the workpiece electrode 8 is zero and the potential of the tool electrode 7 is negative until t3Steady state voltage after the moment is-UrAt the interval of the pulse ToffThe process of equal energy deionization in the machining gap is completed in a period of time, and | -Ur|<|Ude|；
At [ t ]0，t5]Charging the capacitance induction high-voltage ignition module 2 to t4Steady state voltage after the moment is Uig，UigA high voltage ignition voltage;
at [ t ]5，t10]The capacitance induction high-voltage ignition module 2 is connected between the tool electrode 7 and the workpiece electrode 8 in a positive polarity mode in the period, and the discharge is carried out on the ignition module and is rapidly discharged to t7At the moment, the interelectrode voltage quickly reaches the breakdown critical voltage UD(ii) a After [ t ]7，t8]The time period is discharge delay; [ t ] of8，t9]The interelectrode medium is broken down in the period to form a plasma discharge channel, and simultaneously, the capacitance induced high-voltage ignition module 2 is continuously discharged until t9Reach steady state at all times, namely reach interpolar maintenance voltage UT(ii) a T formed in the plasma discharge channel8，t9]During the period, a low-voltage processing pulse current (I) is switched onp0) Performing electric discharge machining until t11Pulse width T of time machining pulseonFinishing the discharge machining process in one pulse period; and | Ude|<|UT|<|UD|<|Uig|。
In an alternative implementation of the embodiments of the present invention, the inter-pulse ToffAnd a pulse width TonAll are 10 microseconds, and the duty cycle is adjustable. U shapedeAbout 30V, UrApproximately minus 10 volts, UDAbout 90V, UTAbout 36V, UigAbout 120 volts or so.
Further, the operation process of the inter-pulse capacitance equal-energy deionization module 1 comprises the following steps:
as shown in fig. 3(a) and 3(b), at [ t ]0，t2]Time period, first switch S1And a fourth switch S4Open, second switch S2And a third switch S3Closed, charging current Ic_deFrom the firstCharging power supply Vcc1Flows out through a third switch S3A first capacitor CdeAnd a second switch S2Inflow ground Gnd1(ii) a A first capacitor CdeHas a charging steady-state voltage of Ude，Ude≈Vcc1；
At [ t ]2，t5]Time period, first switch S1And a fourth switch S4Closed, second switch S2And a third switch S3Disconnecting the workpiece electrode, wherein the output end N is a positive end and is connected with the workpiece electrode 8, the output end M is a negative end and is connected with the tool electrode 7, and discharging the energy deionization module 1 such as inter-pulse capacitance and the like;
at [ t ]5，t6]The time period and t6T to the next pulse period0Time period, first switch S1A second switch S2And a third switch S3And a fourth switch S4Are all disconnected.
In an optional implementation manner of the embodiment of the present invention, the first charging power supply Vcc1About 30V, and a first capacitor Cde330 picofarads.
Further, as shown in fig. 4(a) and 4(b), the operation of the capacitive induction high voltage ignition module 2 includes:
at [ t ]0，t5]Time period, fifth switch S5And an eighth switch S8Open, sixth switch S6And a seventh switch S7Closed, charging current Ic_igFrom the second charging source VccHFlows out through a sixth switch S6A second capacitor CigAnd a seventh switch S7Inflow ground Gnd2(ii) a Second capacitor CigHas a charging steady-state voltage of Uig，Uig≈VccH；
At [ t ]5，t10]Time period, fifth switch S5And an eighth switch S8Closed, sixth switch S6And a seventh switch S7Disconnecting the high-voltage ignition module, wherein the high-voltage ignition output end H is a positive end and is connected with the tool electrode 7, the output end N is a negative end and is connected with the workpiece electrode 8, and discharging is carried out on the capacitance induction high-voltage ignition module 2;
at [ t ]10，t11]The time period and t11T to the next pulse period0Time period, fifth switch S5And a sixth switch S6Seventh switch S7And an eighth switch S8Are all disconnected.
In an optional implementation manner of the embodiment of the present invention, the second charging power supply VccHIs about 120V and is connected with a first charging power supply Vcc1Not common to ground, a second capacitor CigAbout 2200 picofarads.
In practical application, a cylindrical tungsten wire with the diameter of one hundred microns is adopted as a tool electrode 7; a metal flat plate having a surface area several orders of magnitude larger than the lower end surface of the tool electrode 7 is used as the workpiece electrode 8; deionized water, kerosene or electric working fluid is adopted as working fluid; the tool electrode 7, the metal flat workpiece electrode 8, the working fluid and the capacitance-induced micro electric spark machining pulse power supply form a micro electric spark machining system.
In the embodiment of the invention, the inter-pulse energy deionization module 1 such as inter-pulse capacitance is used for processing the inter-pulse T of the signaloffDuring the period, the ignition initial state is fixed at a negative voltage (-U) with a small absolute valuer) (ii) a Then the capacitor is used for inducing the high-voltage ignition module 2 to generate a signal with a pulse width TonIn the ignition initial state of the period, a large capacitance is induced by thousands of picofarads full of energy in a very short time, and the high-voltage ignition voltage U of the large capacitance isigThe discharge current reaches hundred and ten volts, the discharge current is switched into the interelectrode in a positive polarity mode, the abrupt electric field energy and the electromagnetic field energy caused by the abrupt change of the electric field are applied to the interelectrode, the interelectrode medium is promoted to be rapidly ionized in a large quantity to generate avalanche breakdown, the discharge delay time is greatly shortened, the discharge current density is improved, and the capacitance induction type micro-spark discharge process with fixed ignition initial state, controllable ignition energy, short discharge delay and high discharge rate is realized. The capacitance induction type micro spark discharge process is combined with a single pulse power supply technology with small and controllable pulse energy and high discharge rate, so that the processing efficiency and the surface quality are effectively improved. Has important significance for developing the electric machining technology in China and improving the electric spark machining process level of the micro structure (micro hole and micro three-dimensional structure).
In summary, according to the technical scheme of the invention, the capacitance-induced micro-spark discharge process is combined with the high-efficiency machining pulse power supply technology, and the equal energy mode with good discharge consistency is unified with the equal pulse width mode with higher discharge frequency and machining speed. The capacitance induction type high-efficiency pulse power supply is utilized to carry out micro electric spark machining, so that the discharge rate, the discharge consistency and the energy utilization rate can be effectively improved.
In addition, the invention can also shorten the breakdown delay, realize the short-time high-current-density micro spark discharge process, and effectively improve the processing efficiency, the surface quality and the processing stability while finishing the high-precision and high-quality micro electric spark processing.
The invention combines the characteristic of small stray capacitance between poles in micro-electric machining, fixes the initial ignition state to a negative voltage with a small absolute value (the potential of a workpiece is zero potential, the potential of a tool is negative at the moment, the potential is called as negative polarity, and is opposite to the processing), and in the initial ignition state, a large induced capacitor full of energy is connected between poles in a positive polarity mode in a very short time, and sudden electric field energy and electromagnetic field energy caused by the sudden change of the electric field are applied to the poles to promote the medium between the poles to be quickly and greatly ionized to generate avalanche breakdown, thereby greatly shortening the discharge delay time, simultaneously improving the discharge current density, and realizing the capacitance induced micro-spark discharge process with fixed initial ignition state, controllable ignition energy, short discharge delay and high discharge rate. The capacitance induction type micro spark discharge process is combined with a single pulse power supply technology with small and controllable pulse energy and high discharge rate, so that the processing efficiency and the surface quality are improved.
It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the description of the present invention, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
While the foregoing is directed to embodiments of the present invention, other modifications and variations of the present invention may be devised by those skilled in the art in light of the above teachings. It should be understood by those skilled in the art that the foregoing detailed description is for the purpose of better explaining the present invention, and the scope of the present invention should be determined by the scope of the appended claims.
Claims (9)
1. A capacitance-induced micro electro-discharge machining pulse power supply, comprising:
the device comprises an inter-pulse capacitance equal-energy deionization module (1), a capacitance induction high-voltage ignition module (2), a voltage detection module (3), a non-contact current detection module (4), a high-voltage ignition-pulse current selector (5) and a capacitance induction micro electric spark discharge control module (6);
the first end of the high-voltage ignition-pulse current selector (5) is connected with the capacitor inductorA high-voltage ignition output end (H) of the high-voltage ignition module (2) is connected with a second end of the high-voltage ignition module and a processing pulse current (I)p0) The output end (M) is connected with a tool electrode (7);
the workpiece electrode (8) is connected with the output end (N) of the capacitance induced high-voltage ignition module (2), and a connecting wire penetrates through the non-contact current detection module (4);
the first end of the inter-pulse capacitance equal-energy deionization module (1) is connected with the output end (M) of the high-voltage ignition-pulse current selector (5), and the second end of the inter-pulse capacitance equal-energy deionization module is connected with the output end (N) of the capacitance induction high-voltage ignition module (2);
working liquid is filled between the tool electrode (7) and the workpiece electrode (8); the first end of the voltage detection module (3) is connected with the tool electrode (7), and the second end is connected with the workpiece electrode (8);
the capacitance-induced micro electric spark discharge control module (6) is connected with the inter-pulse capacitance equal-energy deionization module (1), the capacitance-induced high-voltage ignition module (2), the voltage detection module (3) and the non-contact current detection module (4).
2. A pulsed power supply according to claim 1, characterized in that the inter-pulse capacitive isoenergetic deionization module (1) comprises:
first charging power supply (V)cc1) A first capacitor (C)de) A first switch (S)1) A second switch (S)2) And a third switch (S)3) And a fourth switch (S)4)；
The first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Forming an H bridge.
3. A pulsed power supply according to claim 2, characterized in that the capacitive induction high voltage ignition module (2) comprises:
second charging power supply (V)ccH) A second capacitor (C)ig) And a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And an eighth switch (S)8)；
The fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Forming an H bridge.
4. Pulsed power supply according to claim 3, characterized in that the first charging source (V)cc1) At 30 volts, the first capacitance (C)de) 330 picofarads; the second charging power supply (V)ccH) 120V, the second capacitance (C)ig) 2200 picofarads; the first charging power supply (V)cc1) And the second charging power supply (V)ccH) Not common to ground.
5. Pulsed power supply according to claim 3, characterized in that the first switch (S)1) A second switch (S)2) A third switch (S3), a fourth switch (S4), a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And an eighth switch (S)8) Is a MOS tube or a triode or an insulated gate bipolar transistor IGBT or controllable silicon.
6. A method of operating a capacitive induced micro electro discharge machining pulsed power supply as claimed in any one of claims 1 to 5, comprising:
the capacitance-induced micro electric spark discharge control module (6) performs servo control of short circuit, open circuit and machining according to output signals of the voltage detection module (3) and the non-contact current detection module (4);
the capacitance-induced micro electric spark discharge control module (6) is used for controlling the electric spark discharge according to the machining pulse current (I)p0) Pulse width T ofonAnd the interpulse ToffThe pulse-to-pulse deionization control is carried out on the pulse-to-pulse capacitance equal-energy deionization module (1), and the pulse width high-voltage ignition process control is carried out on the capacitance induction high-voltage ignition module (2).
7. Working method according to claim 6, characterized in that [0, t ]5]For machining pulsed currents (I)p0) One pulse periodPeriodic interpulse Toff，[t5，t11]For machining pulsed currents (I)p0) Pulse width T of one pulse periodon；
At [ t ]0，t2]Charging the inter-pulse capacitance equal-energy deionization module (1) for a period of time until t1Steady state voltage after the moment is Ude；
At [ t ]2，t5]Connecting the inter-pulse capacitance equal-energy deionization module (1) between the tool electrode (7) and the workpiece electrode (8) in a negative polarity mode, wherein the potential of the workpiece electrode (8) is zero, the potential of the tool electrode (7) is negative, discharging is carried out on the workpiece electrode until t3Steady state voltage after the moment is-UrAt the interval of the pulse ToffThe process of equal energy deionization in the machining gap is completed in a period of time, and | -Ur|<|Ude|；
At [ t ]0，t5]Charging the capacitive induction high voltage ignition module (2) for a period of time up to t4Steady state voltage after the moment is Uig，UigA high voltage ignition voltage;
at [ t ]5，t10]The capacitance induction high-voltage ignition module (2) is connected between the tool electrode (7) and the workpiece electrode (8) in a positive polarity mode in a time period, and is discharged to t7At the moment, the interelectrode voltage quickly reaches the breakdown critical voltage UD(ii) a After [ t ]7，t8]The time period is discharge delay; [ t ] of8，t9]The interelectrode medium is broken down in the period to form a plasma discharge channel, and meanwhile, the capacitance induced high-voltage ignition module (2) is continuously discharged until t9Reach steady state at all times, namely reach interpolar maintenance voltage UT(ii) a T formed in the plasma discharge channel8，t9]During the period, a machining pulse current (I) is switched onp0) Performing electric discharge machining until t11Pulse width T of time machining pulseonFinishing the discharge machining process in one pulse period; and | Ude|<|UT|<|UD|<|Uig|。
8. The operating method according to claim 7, characterized in that said inter-pulse capacitive isoenergetic deionization module (1) comprises: first charging power supply (V)cc1) A first capacitor (C)de) A first switch (S)1) A second switch (S)2) And a third switch (S)3) And a fourth switch (S)4) (ii) a The first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Forming an H bridge;
the working process of the inter-pulse capacitance equal-energy deionization module (1) comprises the following steps:
at [ t ]0，t2]Time period, the first switch (S)1) And a fourth switch (S)4) Open, the second switch (S)2) And the third switch (S)3) Closed, charging current (I)c_de) By the first charging power supply (V)cc1) Flows out through the third switch (S)3) The first capacitor (C)de) And said second switch (S)2) Flowing into the ground (Gnd)1) (ii) a The first capacitor (C)de) Has a charging steady-state voltage of Ude，Ude≈Vcc1；
At [ t ]2，t5]Time period, the first switch (S)1) And the fourth switch (S)4) Closed, the second switch (S)2) And the third switch (S)3) Disconnecting the workpiece electrode (8) and the tool electrode (7) and discharging the inter-pulse capacitance isoenergetic deionization module (1), wherein the output end (N) is a positive end and is connected with the workpiece electrode (8), and the output end (M) is a negative end;
at [ t ]5，t6]The time period and t6T to the next pulse period0Time period, the first switch (S)1) The second switch (S)2) The third switch (S)3) And the fourth switch (S)4) Are all disconnected.
9. Operating method according to claim 7, characterized in that the capacitanceThe high pressure ignition inducing module (2) comprises: second charging power supply (V)ccH) A second capacitor (C)ig) And a fifth switch (S)5) And a sixth switch (S)6) And a seventh switch (S)7) And an eighth switch (S)8) (ii) a The fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Forming an H bridge;
the working process of the capacitance induction high-voltage ignition module (2) comprises the following steps:
at [ t ]0，t5]Time period, the fifth switch (S)5) And the eighth switch (S)8) Open, the sixth switch (S)6) And the seventh switch (S)7) Closed, charging current (I)c_ig) By the second charging power supply (V)ccH) Flows out through the sixth switch (S)6) The second capacitor (C)ig) And the seventh switch (S)7) Flowing into the ground (Gnd)2) (ii) a The second capacitance (C)ig) Has a charging steady-state voltage of Uig，Uig≈VccH；
At [ t ]5，t10]Time period, the fifth switch (S)5) And the eighth switch (S)8) Closed, the sixth switch (S)6) And the seventh switch (S)7) Disconnecting the high-voltage ignition module (2), wherein a high-voltage ignition output end (H) is a positive end and is connected with the tool electrode (7), and an output end (N) is a negative end and is connected with the workpiece electrode (8);
at [ t ]10，t11]The time period and t11T to the next pulse period0Time period, the fifth switch (S)5) The sixth switch (S)6) The seventh switch (S)7) And the eighth switch (S)8) Are all disconnected.
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| JPS5467296A (en) * | 1978-07-29 | 1979-05-30 | Inoue Japax Res Inc | Discharge processing device |
| EP0027041A1 (en) * | 1979-10-05 | 1981-04-15 | Fanuc Ltd. | Wire-cut electric-discharge machine, a power source for such a machine, and a method of wire-cut electric-discharge machining |
| CN1100980A (en) * | 1993-06-30 | 1995-04-05 | 三菱电机株式会社 | Method and apparatus for electrical discharge machining using variable capacitance and variable inductance |
| CN1586780A (en) * | 2004-10-18 | 2005-03-02 | 苏州三光科技有限公司 | Pulse power source for electric working machine tool |
| CN101700589A (en) * | 2009-11-04 | 2010-05-05 | 山东大学 | Piezoelectric self-excited impulse-type micro electro discharge machining device and machining method thereof |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5467296A (en) * | 1978-07-29 | 1979-05-30 | Inoue Japax Res Inc | Discharge processing device |
| EP0027041A1 (en) * | 1979-10-05 | 1981-04-15 | Fanuc Ltd. | Wire-cut electric-discharge machine, a power source for such a machine, and a method of wire-cut electric-discharge machining |
| CN1100980A (en) * | 1993-06-30 | 1995-04-05 | 三菱电机株式会社 | Method and apparatus for electrical discharge machining using variable capacitance and variable inductance |
| CN1586780A (en) * | 2004-10-18 | 2005-03-02 | 苏州三光科技有限公司 | Pulse power source for electric working machine tool |
| CN101700589A (en) * | 2009-11-04 | 2010-05-05 | 山东大学 | Piezoelectric self-excited impulse-type micro electro discharge machining device and machining method thereof |
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