CN111644718B - Pulse power supply for smooth machining of medium-speed wire cutting and machining method thereof - Google Patents

Pulse power supply for smooth machining of medium-speed wire cutting and machining method thereof Download PDF

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CN111644718B
CN111644718B CN201911416890.3A CN201911416890A CN111644718B CN 111644718 B CN111644718 B CN 111644718B CN 201911416890 A CN201911416890 A CN 201911416890A CN 111644718 B CN111644718 B CN 111644718B
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gap
switch tube
current
voltage
circuit
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CN111644718A (en
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杨飞
史顺飞
覃德凡
吴鹏程
邵佳钰
汪志鹏
王一娉
徐大波
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Nanjing University of Science and Technology
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Nanjing University of Science and Technology
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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
    • B23H7/00—Processes or apparatus applicable to both electrical discharge machining and electrochemical machining
    • B23H7/14—Electric circuits specially adapted therefor, e.g. power supply
    • 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
    • B23H11/00—Auxiliary apparatus or details, not otherwise provided for
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

The invention discloses a pulse power supply for smooth machining of medium-speed wire cutting, which comprises a main power circuit, a voltage detection circuit, a current detection circuit and an FPGA (field programmable gate array) digital control circuit, wherein the main power circuit is used for charging a gap and providing discharge energy for three times of machining; the current detection circuit and the voltage detection circuit are used for detecting current and voltage signals of a gap in the three-cutter machining process in real time; the FPGA digital control circuit is used for generating PWM signals according to real-time gap voltage and current signals, controlling the on-off of a switch tube in the main power circuit, preventing electrolysis between every two processed discharge pulses and pressing the discharge energy of the third knife to the lowest on the premise of gap breakdown. The invention ensures the smooth finish of the surface of the workpiece and improves the processing quality of the power supply to the surface of the workpiece.

Description

Pulse power supply for smooth machining of medium-speed wire cutting and machining method thereof
Technical Field
The invention relates to a high-frequency pulse power supply for high-speed reciprocating wire-cut electric spark wire cutting, in particular to a pulse power supply for smooth machining of medium-speed wire-cut wire cutting and a machining method thereof.
Background
With the continuous development of modern industry, the materials to be machined are also various, the machining requirement precision, the machining difficulty, the machining speed and the working efficiency have great requirements, most of pulse power supplies used by the existing machining tool still adopt a resistance type, the current cannot be controlled, and the energy loss is serious, so that the existing traditional machining mode is difficult to meet the requirement of complaint. With the development of power electronic technology, an energy-saving pulse power supply for wire cut electrical discharge machining begins to be gradually introduced into the power electronic technology, at present, a small part of energy-saving non-resistance pulse power supply simply introduces inductive energy storage discharge, although the current can be controlled to a certain extent, the actual machining surface is not good in finish degree, because the conductivity of a wire cutting working solution exists, leakage current exists when a gap is not broken, the discharge energy is influenced, and in addition, the inductive energy continues to flow after a main power loop is disconnected, so that the discharge pulse width of a third knife is larger, the energy of the knife for repairing the third knife is larger, and the roughness of the machined surface of a workpiece cannot be further improved due to excessive knife repairing, so that a pulse power supply for wire cut finish machining of a medium-speed wire cut wire is required to be developed according to the surface finish degree of the workpiece.
Disclosure of Invention
The invention aims to provide a pulse power supply for cutting, polishing and processing medium-speed wire and a control method thereof.
The technical solution for realizing the purpose of the invention is as follows: a pulse power supply for medium-speed wire cutting smooth machining comprises a main power circuit, a voltage detection circuit, a current detection circuit and an FPGA digital control circuit, wherein the main power circuit is used for charging a gap and providing discharge energy of three times of machining; the current detection circuit and the voltage detection circuit are used for detecting current and voltage signals of a gap in the three-cutter machining process in real time; the FPGA digital control circuit is used for generating PWM signals according to the real-time gap voltage and current signals and controlling the on-off of a switch tube in the main power circuit.
Furthermore, the main power loop of the pulse power supply comprises an input direct current source, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, an input capacitor, an inductor, an energy feedback diode and a reverse voltage source, wherein the inductor forms a synchronous rectification Buck circuit, the anode of the energy feedback diode is connected to one end, close to the output anode, of the inductor, the cathode of the energy feedback diode is connected to the anode of the input direct current source, the third switch tube is connected in series between the Buck circuit and the gap anode and is connected with a main power circuit and a reverse voltage source branch circuit, the fourth switch tube is connected in series with the reverse voltage source and is connected in parallel with the output end, and the reverse voltage source anode is connected with the gap cathode.
Further, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube adopt MOSFETs of the Infineon company with the model number of IRF300P 227.
Furthermore, the voltage detection circuit adopts an instrument operational amplification circuit, and voltage is output through a differential sampling gap and is converted into an acceptable voltage range of the FPGA digital-to-analog conversion module.
Further, the current detection circuit adopts a combination of a current detection chip ACS732 and a two-stage operational amplifier AD4084, the current detection chip ACS732 receives a gap current signal and converts the gap current signal into a voltage signal, and the voltage signal is converted into an acceptable voltage range of the FPGA digital-to-analog conversion module through the two-stage operational amplifier AD 4084.
Furthermore, the FPGA digital control circuit comprises an FPGA chip with the model number of EP4CE15F23C8, a digital-to-analog conversion module ALINX9226 and a digital isolation chip ADUM1100, wherein the digital-to-analog conversion module ALINX9226 receives the gap voltage and current analog signals, converts the gap voltage and current analog signals into digital signals and transmits the digital signals to the FPGA, and the FPGA generates a corresponding PWM control driving chip through the digital isolation module ADUM 1100.
The processing method based on the pulse power supply for the medium-speed wire-cut smooth processing comprises the following steps:
the method comprises the following steps: when the first knife processing starts, the FPGA digital control circuit outputs PWM to control the first switch tube, the third switch tube to be conducted, the second switch tube and the fourth switch tube to be disconnected, and the input voltage V is 1 Applying across the gap to charge the gap for breakdown of the gap;
step two: after the gap is broken down, the discharge current starts to rise rapidly, when the current value rises to a current threshold value set by the FPGA, the first switch tube is turned off, the second switch tube is turned on, the inductance of the main power circuit and the current of the gap follow current through the second switch tube and the third switch tube, when the current value of the gap continues to 0A, the third switch tube is turned off, the fourth switch tube is turned on, the back pressure is added into the gap through the fourth switch tube, electrolysis is prevented, and the gap deionization is accelerated until the next discharge period starts;
step three: repeating the first step and the second step, and finishing the first cutting after the set first cutting finishing coordinate is reached;
step four: after the first knife processing is finished, the second knife processing is started, the control time sequence of the second knife processing is consistent with that of the first knife, the first switch tube and the third switch tube are conducted, the second switch tube and the fourth switch tube are turned off, and the input voltage V is 1 Applying across the gap to charge the gap for breakdown of the gap;
step five: after the gap is broken down, the discharge current starts to rise rapidly, when the current value rises to a current threshold value set by the FPGA, the first switch tube is turned off, the second switch tube is turned on, the inductance of the main power circuit and the current of the gap follow current through the second switch tube and the third switch tube, when the current value of the gap continues to 0A, the third switch tube is turned off, the fourth switch tube is turned on, the back pressure is added into the gap through the fourth switch tube, electrolysis is prevented, and the gap deionization is accelerated until the next discharge period starts;
step six: repeating the fourth step and the fifth step, and finishing the processing of the second cutter after the set second cutter finishing coordinate is reached;
step seven: after the second knife machining is finished, the third knife machining is started, the FPGA digital control circuit outputs PWM to control the first switch tube and the third switch tube to be conducted, the second switch tube and the fourth switch tube to be switched off, and the input voltage V is 1 Applying across the gap to charge the gap for breakdown of the gap;
step eight: after the gap breakdown, the discharge current starts to rise rapidly, the FPGA starts to detect a discharge point, the FPGA receives real-time gap voltage data within a certain time range, when the voltage value is detected to be smaller than the last detected voltage value, the gap breakdown is carried out, at the moment, the first switch tube and the third switch tube are turned off, the third switch tube enables the main power loop to be disconnected from the gap, the second switch tube and the fourth switch tube are conducted, the energy in the inductor is fed back to an input direct current source through the energy feedback diode and the second switch tube, the back pressure is added into the gap through the fourth switch tube, the current falling speed is accelerated, the fourth switch tube continues to be conducted for anti-electrolysis after the gap current is reduced to 0A, and the gap deionization is accelerated until the next discharge period starts;
step nine: and repeating the seventh step and the eighth step, finishing the machining of the third cutter after the set third cutter finishing coordinate is reached, and taking out the workpiece.
Compared with the prior art, the invention has the remarkable characteristics that: 1) the main power circuit adopts synchronous rectification Buck, and adopts MOSFET with extremely low on-state resistance to replace a rectifier diode so as to reduce rectification loss, thereby not only greatly improving the efficiency of the DC/DC converter, but also having no dead zone voltage caused by Schottky barrier voltage, being suitable for low-voltage heavy current and having simple structure; 2) the circuit has no output capacitor, the charging speed for the gap is higher, and in the first and second knife machining process, an input direct current source is directly connected into the gap through an inductor, so that the energy and the efficiency of the first and second knife machining are ensured; 3) on the premise of ensuring that the third knife gap can be broken down, gap breakdown point detection is adopted, back pressure is used, the current reduction speed is accelerated, the minimization of knife repairing energy is realized, inductive energy is fed back to an input direct current source through a diode, the energy utilization rate is high, and a circuit is stable; 4) the circuit realizes the electrolysis-preventing function between full-processing discharge pulses, prevents the surface of a workpiece from oxidation-reduction reaction due to electrolysis, and accelerates the deionization process of gaps.
Drawings
FIG. 1 is a system configuration diagram of a pulse power supply for finish-cutting of a wire-moving type wire and a control method thereof according to the present invention.
FIG. 2 is a diagram of a voltage detection circuit according to the present invention.
FIG. 3 is a circuit diagram of the current detection circuit of the present invention.
FIG. 4 is a circuit diagram of the FPGA digital control circuit of the present invention.
Fig. 5 is a structural view of the wire-cut electric discharge machining system according to the present invention.
FIG. 6 is a waveform diagram of voltage and current during the first and second cutting processes of the present invention.
FIG. 7 is a diagram of voltage and current waveforms in the third knife process with breakdown point detection and back pressure measures according to the present invention, wherein (a) is the third knife discharge waveform without gap breakdown point and back pressure, (b) is the third knife discharge waveform with breakdown point detection, and (c) is the third knife discharge waveform with back pressure.
Detailed Description
The scheme of the invention is further explained by combining the attached drawings.
As shown in fig. 1, the pulse power supply for medium-speed wire cutting and finishing comprises a main power circuit, a voltage detection circuit, a current detection circuit and an FPGA digital control circuit, wherein the main power circuit is used for charging a gap and providing discharge energy for three times of processing; the current detection circuit and the voltage detection circuit are used for detecting current and voltage signals of a gap in the three-cutter machining process in real time; the FPGA digital control circuit is used for generating PWM signals according to the real-time gap voltage and current signals and controlling the on-off of a switch tube in the main power circuit.
The main power loop of the pulse power supply comprises an input direct current source and a first switching tube (Q) 1 ) A second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) And a fourth switching tube (Q) 4 ) Input capacitance (C) in ) An inductor (L), an energy feedback diode (D), a reverse voltage source (V) 2 ) Said input capacitance (C) in ) First switch tube (Q) 1 ) A second switch tube (Q) 2 ) The inductor (L) forms a synchronous rectification Buck circuit, the anode of the energy feedback diode (D) is connected with one end of the inductor close to the output anode, the cathode of the energy feedback diode (D) is connected with the anode of the input direct current source, and the switching tube (Q) 3 ) Is connected in series between the Buck circuit and the positive pole of the gap, and is connected with the main power circuit and the reverse voltage source branch circuit, and the switching tube (Q) 4 ) The series reverse voltage source is connected in parallel with the output end, and the positive pole of the reverse voltage source is connected with the negative pole of the gap.
The first switch tube (Q) 1 ) A second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) A fourth switch tube (Q) 4 ) The voltage V of DS is the voltage V of an MOSFET with the model number of IRF300P227 manufactured by Infineon company DSS 300V, rated current I D 50A, the voltage and current requirements needed by linear cutting machining are basically met, the on-resistance of the switching tube is 33m omega, the on-rise time is 43ns, the on-delay time is 16ns, and the rapid charging breakdown of the gap is guaranteed. The energy feedback diode D is MUR40250T in reverse directionThe breakdown voltage is 250V, the rated current is 40A, the daily processing requirement of medium-speed wire cutting is met, the inductor L adopts a flat copper conductor inductor, and the through-current capacity is high.
As shown in fig. 2, the voltage detection circuit adopts an operational amplifier circuit for an instrument, and outputs a voltage through a differential sampling gap to be converted into an acceptable voltage range of the FPGA digital-to-analog conversion module.
As shown in fig. 3, the current detection circuit adopts a combination of a current detection chip ACS732 and a two-stage operational amplifier AD4084, the current detection chip ACS732 receives a gap current signal and converts the gap current signal into a voltage signal, and the voltage signal is converted into an acceptable voltage range of the FPGA digital-to-analog conversion module through the two-stage operational amplifier AD 4084.
As shown in fig. 4, the FPGA digital control circuit includes an FPGA chip with model number EP4CE15F23C8, a digital-to-analog conversion module ALINX9226, and a digital isolation chip ADUM 1100. The digital-to-analog conversion module ALINX9226 receives the gap voltage and current analog signals, converts the gap voltage and current analog signals into digital signals and transmits the digital signals to the FPGA, and the FPGA generates a corresponding PWM control driving chip through the digital isolation module ADUM 1100.
As shown in fig. 5, the medium-speed wire cut electrical discharge machining system includes a pulse power supply, a workpiece, a wire storage cylinder, a wire electrode, a motor, a water pump, a servo and the like in a machine tool, when the pulse power supply is powered on, the positive electrode is connected with the workpiece, the negative electrode is connected with the wire electrode, the motor drives the wire electrode on the wire storage cylinder to rotate in a reciprocating manner, when the wire electrode and the workpiece reach a certain distance, a gap is punctured, and the wire electrode and the workpiece are subjected to electrical discharge machining through a working fluid.
As shown in fig. 6, for the waveform of the discharge voltage and current during the first and second processes of the present invention, when the process starts, the corresponding switch tube is turned on to charge the gap, the gap voltage rises rapidly, after breakdown, the gap forms a constant sustain voltage, at this time, the current starts to rise rapidly, when the current peak reaches the current threshold set in the FPGA, the corresponding switch tube is turned off, the current starts to fall, and after the current peak falls to 0, the back voltage is added to prevent electrolysis, so as to accelerate the deionization of the gap.
As shown in fig. 7, a discharge voltage and current waveform during the third blade machining according to the present invention is obtained, gap breakdown point detection is introduced during the third blade machining, the main circuit upper tube and the cutoff tube start machining after being conducted, the FPGA detects a gap voltage, when it is detected that the current voltage value is smaller than the last detected voltage value, the main circuit upper tube and the cutoff tube are turned off, the lower tube and the negative pressure tube are conducted after dead time, the current starts to decrease, and the back pressure applied to the two ends of the gap accelerates the current decrease speed, reduces the discharge pulse width, and reduces the discharge energy of the third blade.
In summary, the processing method of the pulse power supply for the medium-speed wire cutting and smoothing processing comprises the following steps:
the method comprises the following steps: when the first knife processing starts, the FPGA digital control circuit outputs PWM to control a first switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage V 1 Applied across the gap to charge the gap for gap breakdown.
Step two: the discharge current starts to rise rapidly after the gap breakdown, and when the current value rises to the current threshold value set by the FPGA, the first switch tube (Q) 1 ) Off, second switching tube (Q) 2 ) The current conducted to the main power circuit inductor (L) and the gap passes through the second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) Afterflow, when the gap current value afterflows to 0A, the third switch tube (Q) 3 ) Off, fourth switching tube (Q) 4 ) Conducting and reverse voltage passing through the fourth switch tube (Q) 4 ) Adding the gap, performing anti-electrolysis, and accelerating gap deionization until the next discharge period begins.
Step three: and repeating the first step and the second step, and finishing the first cutting after the set first cutting finishing coordinate is reached.
Step four: and starting the second knife after the first knife is finished, wherein the control time sequence of the second knife is consistent with that of the first knife. First switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage V 1 Applied across the gap to charge the gap for gap breakdown.
Step five: the discharge current begins to rise rapidly after the gap breakdown, and when the current value rises toAfter the current threshold value set by FPGA, the first switch tube (Q) 1 ) Off, second switching tube (Q) 2 ) The current conducted to the main power circuit inductor (L) and the gap passes through the second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) Afterflow, when the gap current value afterflows to 0A, the third switch tube (Q) 3 ) Off, fourth switching tube (Q) 4 ) Conducting and reverse voltage passing through the fourth switch tube (Q) 4 ) Adding the gap, performing anti-electrolysis, and accelerating gap deionization until the next discharge period begins.
Step six: and repeating the fourth step and the fifth step, and finishing the second cutter after the set second cutter finishing coordinate is reached.
Step seven: after the second knife is finished, the third knife is started to be processed, the FPGA digital control circuit outputs PWM to control the first switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage V 1 Applied across the gap to charge the gap for gap breakdown.
Step eight: after the gap breakdown, the discharge current starts to rise rapidly, the FPGA starts to detect the discharge point, the FPGA receives real-time gap voltage data within a certain time range, when the voltage value is detected to be smaller than the last detected voltage value, the gap breakdown is carried out, and the first switch tube (Q) is switched off at the moment 1 ) And a third switching tube (Q) 3 ) A third switching tube (Q) 3 ) The main power loop is disconnected with the gap, and the second switch tube (Q) is conducted 2 ) And a fourth switching tube (Q) 4 ) The energy in the inductor (L) is fed back to the diode (D) and the second switch tube (Q) through the energy 2 ) Follow current, feedback to the input DC source, back voltage passing through the fourth switching tube (Q) 4 ) Adding gap to accelerate the current reduction speed, and after the gap current is reduced to 0A, the fourth switch tube (Q) 4 ) And continuing to conduct for electrolysis prevention, and accelerating the gap deionization until the next discharge period begins.
Step nine: and repeating the seventh step and the eighth step, finishing the machining of the third cutter after the set third cutter finishing coordinate is reached, and taking out the workpiece.
In the scheme, the processing graph is drawn before processing, the first cutter is automatically switched to the second cutter for cutter repair after the first cutter is processed to the set position coordinate, and the third cutter is automatically started after the second cutter is repaired to the set coordinate.
In summary, the invention realizes controllable discharge energy in a single period by tightly combining the pulse power supply circuit principle and the digital control mode. The main power circuit adopts a synchronous rectification Buck converter, the structure is simple, the circuit is stable, on the premise of ensuring the processing efficiency of the first and second cutters, the third cutter introduces a cross point detection and back pressure measure between gaps, the FPGA digital control circuit is used for setting a voltage current threshold value, receives a real-time gap voltage current signal to perform digital-to-analog conversion, compares the voltage current threshold value with a given threshold value, outputs a PWM signal to control the on-off of a switching tube, minimizes the discharge energy on the premise of gap breakdown, realizes electrolysis prevention in the full processing process, prevents the surface of a workpiece from oxidation reduction reaction due to electrolysis, and makes the processing surface optimal on the aspect of a pulse power supply.

Claims (6)

1. The pulse power supply for the medium-speed wire cutting smooth machining is characterized by comprising a main power circuit, a voltage detection circuit, a current detection circuit and an FPGA digital control circuit, wherein the main power circuit is used for charging a gap and providing discharge energy for three times of machining; the current detection circuit and the voltage detection circuit are used for detecting current and voltage signals of a gap in the three-cutter machining process in real time; the FPGA digital control circuit is used for generating a PWM signal according to the real-time gap voltage and current signal and controlling the on-off of a switch tube in the main power circuit;
the main power loop of the pulse power supply comprises an input direct current source and a first switching tube (Q) 1 ) A second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) And a fourth switching tube (Q) 4 ) Input capacitance (C) in ) An inductor (L), an energy feedback diode (D), a reverse voltage source (V) 2 ) Said input capacitance (C) in ) First switch tube (Q) 1 ) A second switch tube (Q) 2 ) The inductor (L) forms a synchronous rectification Buck circuit, the anode of the energy feedback diode (D) is connected with one end of the inductor close to the output anode,the cathode is connected with the anode of an input direct current source, and the third switching tube (Q) 3 ) Is connected in series between the Buck circuit and the positive pole of the gap, and is connected with the main power circuit and the reverse voltage source branch circuit, and the fourth switching tube (Q) 4 ) The series reverse voltage source is connected in parallel with the output end, and the positive pole of the reverse voltage source is connected with the negative pole of the gap.
2. The pulse power supply for medium-speed wire-cut finishing according to claim 1, wherein said first switch tube (Q) 1 ) A second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) And a fourth switching tube (Q) 4 ) A MOSFET model IRF300P227 from Infineon is used.
3. The pulse power supply for medium-speed wire-cut finishing according to claim 1, wherein the voltage detection circuit adopts an instrument operational amplifier circuit, and outputs a voltage through a differential sampling gap to be converted into an acceptable voltage range of the FPGA digital-to-analog conversion module.
4. The pulse power supply for cutting and finishing the medium-speed wire according to claim 1, wherein the current detection circuit is formed by combining a current detection chip ACS732 and a two-stage operational amplifier AD4084, the current detection chip ACS732 receives a gap current signal and converts the gap current signal into a voltage signal, and the voltage signal is converted into an acceptable voltage range of the FPGA digital-to-analog conversion module through the two-stage operational amplifier AD 4084.
5. The pulse power supply for medium-speed wire-cut finishing according to claim 1, wherein the FPGA digital control circuit comprises an FPGA chip with model number EP4CE15F23C8, a digital-to-analog conversion module ALINX9226, and a digital isolation chip ADUM1100, the digital-to-analog conversion module ALINX9226 receives the gap voltage current analog signal, converts the gap voltage current analog signal into a digital signal, and transmits the digital signal to the FPGA, and the FPGA generates a corresponding PWM control driving chip through the digital isolation module ADUM 1100.
6. The method for processing the pulse power supply for the medium-speed wire-cut finishing process according to any one of claims 1 to 5, comprising the steps of:
the method comprises the following steps: when the first knife processing starts, the FPGA digital control circuit outputs PWM to control a first switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage (V) 1 ) Applying across the gap to charge the gap for breakdown of the gap;
step two: after the gap breakdown, the discharge current starts to rise rapidly, and when the current value rises to the current threshold value set by the FPGA, the first switch tube (Q) is connected with the second switch tube 1 ) Off, second switching tube (Q) 2 ) The current of the main power circuit inductance (L) and the gap passes through the second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) Afterflow, when the gap current value afterflows to 0A, the third switch tube (Q) 3 ) Off, fourth switching tube (Q) 4 ) Conducting and reverse voltage passing through the fourth switch tube (Q) 4 ) Adding gaps, performing anti-electrolysis, and accelerating gap deionization until the next discharge period begins;
step three: repeating the first step and the second step, and finishing the first cutting after the set first cutting finishing coordinate is reached;
step four: starting the second knife after the first knife is finished, wherein the control time sequence of the second knife is consistent with that of the first knife, and a first switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage (V) 1 ) The two ends of the gap are added to charge the gap so as to break down the gap;
step five: the discharge current starts to rise rapidly after the gap breakdown, and when the current value rises to the current threshold value set by the FPGA, the first switch tube (Q) 1 ) Off, second switching tube (Q) 2 ) The current conducted to the main power circuit inductor (L) and the gap passes through the second switch tube (Q) 2 ) And a third switching tube (Q) 3 ) Afterflow, when the gap current value afterflows to 0A, the third switch tube (Q) 3 ) Off, fourth switching tube (Q) 4 ) Conducting and reverse voltage passing through the fourth switch tube (Q) 4 ) Adding gaps, performing anti-electrolysis, and accelerating gap deionization until the next discharge period begins;
step six: repeating the fourth step and the fifth step, and finishing the processing of the second cutter after the set second cutter finishing coordinate is reached;
step seven: after the second knife is finished, the third knife is started to be processed, the FPGA digital control circuit outputs PWM to control the first switch tube (Q) 1 ) And a third switching tube (Q) 3 ) Conducting, second switch tube (Q) 2 ) Fourth switch tube (Q) 4 ) Off, input voltage (V) 1 ) Applying across the gap to charge the gap for breakdown of the gap;
step eight: after gap breakdown, the discharge current starts to rise rapidly, the FPGA starts to perform discharge point detection, the FPGA receives real-time gap voltage data within a certain time range, when the voltage value is detected to be smaller than the last detected voltage value, the gap breakdown is performed, and at the moment, the first switch tube (Q) is switched off 1 ) And a third switching tube (Q) 3 ) A third switching tube (Q) 3 ) The main power loop is disconnected with the gap, and the second switch tube (Q) is conducted 2 ) And a fourth switching tube (Q) 4 ) The energy in the inductor (L) is fed back to the diode (D) and the second switch tube (Q) through the energy 2 ) Follow current, feedback to the input DC source, back voltage passing through the fourth switching tube (Q) 4 ) Adding gap to accelerate the current reduction speed, and after the gap current is reduced to 0A, the fourth switch tube (Q) 4 ) Continuing to conduct for electrolysis prevention, and accelerating the gap deionization until the next discharge period begins;
step nine: and repeating the seventh step and the eighth step, finishing the machining of the third cutter after the set third cutter finishing coordinate is reached, and taking out the workpiece.
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