Multi-channel discharge detection and control method and device in electric spark mirror finishing
By detecting the discharge state and adjusting the toner concentration, the problems of capacitance effect and powder separation in EDM mirror finishing were solved, enabling large-area stable mirror finishing and improving the performance and lifespan of the machining fluid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHUHAI HERUI NEW TECH CO LTD
- Filing Date
- 2026-02-05
- Publication Date
- 2026-05-01
AI Technical Summary
Electrical discharge machining (EDM) for mirror surfaces is limited by the capacitance effect, making large-area machining difficult. Furthermore, the discharge state in existing machining fluids is difficult to control, resulting in poor versatility and stability.
By detecting the rising edge of the current and the breakdown delay of the discharge voltage in the discharge circuit, single-channel, multi-channel, and abnormal discharge states are identified, and control actions are executed according to different states to adjust the toner concentration and achieve stable control of multi-channel discharge.
It achieves stability and versatility in large-area mirror surface processing, avoids the need for additional powder, solves the powder separation problem, and improves the performance and lifespan of the processing fluid.
Smart Images
Figure CN121945903A_ABST
Abstract
Description
A method and apparatus for multi-channel discharge detection and control in electrical discharge mirror machining. Technical Field
[0001] This invention relates to the field of electrical discharge mirror processing technology, specifically to a multi-channel discharge detection and control method and device in electrical discharge mirror processing. Background Technology
[0002] Electrical discharge machining (EDM) offers advantages such as high surface finish, no recast layer, and surface properties consistent with the base material. The machined surface can be directly used as the final forming surface for molds or parts. With the rapid development of 3D printing and high-speed milling technologies for metal materials, the demand for manufacturing complex-shaped parts is increasing. EDM, as an effective supplement to these technologies, has broad application prospects.
[0003] However, the presence of capacitance effect severely limits the application range of EDM mirror finishing. When the machining area is large, the discharge charge easily accumulates in the parasitic capacitance between the tool electrode and the workpiece, resulting in excessive runaway energy in a single discharge, making it impossible to achieve large-area mirror finishing. To solve this problem, existing technologies propose mixed-powder EDM fluids, which improve the conductivity of the machining fluid and reduce the parasitic capacitance value by mixing conductive or semiconductor powders such as aluminum powder and silicon powder into mineral oil, thereby achieving large-area machining. However, these powders are insoluble in mineral oil, requiring continuous stirring, and still suffer from uneven distribution. Furthermore, they are difficult to separate from machining chips, leading to rapid performance degradation and short service life of the machining fluid.
[0004] In addition, in ordinary electrical discharge machining fluids, although the carbon powder and metal shavings produced by the cracking of mineral oil by electrical discharge can form a multi-channel discharge effect similar to that of mixed powder machining fluids, the concentration of carbon powder and shavings is affected by a variety of factors such as tool lifting parameters, electrode shape, discharge parameters, and working fluid state, making it difficult to control precisely. It can only be achieved under the control of highly experienced operators, and its versatility and stability are extremely poor.
[0005] Therefore, there is an urgent need for a technical solution that can achieve stable mirror processing over a large area without the need for additional powder, can precisely control the discharge state, and can achieve this. Summary of the Invention
[0006] In view of this, the purpose of the present invention is to provide a multi-channel discharge detection and control method and device in electrical discharge mirror machining, so as to solve the problems in the prior art of electrical discharge mirror machining being limited by capacitance effect, powder separation problem in mixed powder processing fluid, and difficulty in controlling discharge state in ordinary processing fluid.
[0007] According to a first aspect of the present invention, a method for multi-channel discharge detection and control in electrical discharge machining of mirror surfaces is provided, the method comprising:
[0008] The tool electrode is connected to the negative terminal of the pulse power supply, and the workpiece is connected to the positive terminal of the pulse power supply. The current rising edge slope in the discharge circuit is detected by a DC-DC current rising edge detection device and mapped to an output voltage signal. The output voltage signal is compared with a preset voltage range of multi-channel discharge characteristics to identify the discharge state. The discharge state includes: single-channel discharge, multi-channel discharge, and abnormal discharge. The discharge voltage breakdown delay is detected by a breakdown delay detection circuit. The processing state is determined based on the identified discharge state and the discharge voltage breakdown delay. The processing state includes: toner proliferation mode, toner suppression mode, and dynamic balance mode. Corresponding control actions are executed according to different processing states to increase, decrease, or maintain the toner concentration.
[0009] Preferably, comparing the output voltage signal with a preset voltage range of multi-channel discharge characteristics to identify the discharge state includes: a preset voltage range of multi-channel discharge characteristics. If the output voltage signal of the DC-DC current rising edge detection device This indicates an abnormal discharge state; if the output voltage signal of the DC-DC current rising edge detection device... It is in a single-channel discharge state; if the output voltage signal of the DC-DC current rising edge detection device is... This indicates a multi-channel discharge state.
[0010] Preferably, the breakdown delay detection circuit includes: a discharge gap voltage signal divided by a voltage divider resistor and input to the negative input terminal of a voltage comparator; a reference voltage connected to the positive input terminal of the voltage comparator; an output terminal of the voltage comparator connected to the reset terminal of a counter; a fixed-frequency clock signal connected to the clock terminal of the counter; and an enable terminal of the counter connected to the gate signal of a pulse power supply power switch. When the discharge gap breaks down, the discharge voltage drops, the output of the voltage comparator changes from high to low, and the counter is reset to zero. The counter starts counting when the gate signal of the pulse power supply power switch goes high and stops counting when the output of the voltage comparator changes from high to low. The output of the counter is simultaneously input to the input terminals of a first digital comparator and a second digital comparator, and compared with the first comparison reference of the first digital comparator and the second comparison reference of the second digital comparator. When the output of the counter... When the output result is greater than the first comparison reference, the first digital comparator outputs a high level; when the output result of the counter is greater than the second comparison reference, the second digital comparator outputs a high level. The output of the first digital comparator is connected to the input of the first frequency-to-voltage converter, and is converted into a first output signal that distinguishes between high and low voltage values via frequency-to-voltage conversion. The output of the second digital comparator is connected to the input of the second frequency-to-voltage converter, and is converted into a second output signal that distinguishes between high and low voltage values via frequency-to-voltage conversion. The first output signal represents the result of the breakdown delay exceeding the first reference time; the second output signal represents the result of the breakdown delay exceeding the second reference time. The higher the voltage value of the first output signal, the greater the discharge pulse ratio of the discharge voltage breakdown delay exceeding the first reference time; the higher the voltage value of the second output signal, the greater the discharge pulse ratio of the discharge voltage breakdown delay exceeding the second reference time.
[0011] Preferably, the first reference time is set at the highest point of the rising edge of the multi-channel discharge current, and the second reference time is set at the highest point of the rising edge of the single-channel discharge current.
[0012] Preferably, determining the processing state based on the identified discharge state and the discharge voltage breakdown delay includes: setting a comparison interval for the first output signal. Set the comparison range of the second output signal. If it is a multi-channel discharge state, and the first output signal Second output signal The processing state is in dynamic balance mode; if it is in single-channel discharge state, and the first output signal... Second output signal The processing state is in the toner proliferation mode; if it is in the abnormal discharge state, and the first output signal Second output signal The processing state is in toner suppression mode.
[0013] Preferably, the step of performing corresponding control actions according to different processing states to increase, decrease, or maintain toner concentration includes: if it is a toner proliferation mode, sending a command to the Z-axis servo motor through the controller to reduce the tool lifting height to a preset height range and reduce the tool lifting frequency to below a preset frequency or temporarily stop tool lifting; at the same time, sending a low-frequency command to the variable frequency circulating pump to reduce the flushing fluid flow rate to a preset percentage range of the rated flow rate; and maintaining high-frequency narrow pulse discharge to use the repair electrode to quickly decompose the working fluid and generate new toner to replenish the discharge gap.
[0014] Preferably, the step of performing corresponding control actions according to different processing states to increase, decrease or maintain toner concentration further includes: if it is toner suppression mode, sending a command to the Z-axis servo motor through the controller to raise the tool lifting height to a preset height range; at the same time sending a high-frequency command to the variable frequency circulating pump to increase the flushing fluid flow rate to the rated flow rate; and using the pump suction effect and strong flushing to reduce the ion concentration in the gap.
[0015] Preferably, the step of performing corresponding control actions according to different processing states to increase, decrease or maintain toner concentration further includes: if it is a dynamic balance mode, locking the current Z-axis servo motor and variable frequency circulating pump parameters through the controller, and making slight dynamic corrections within a preset range to stabilize mirror processing.
[0016] According to a second aspect of the present invention, a multi-channel discharge detection and control device for EDM mirror surface machining is provided. The device is applied to the method described in any one of the above-mentioned methods. The device includes: a power connection module for connecting the tool electrode to the negative terminal of the pulse power supply and the workpiece to the positive terminal of the pulse power supply, providing discharge machining conditions with narrow pulse width and high peak current; a detection feedback terminal for detecting the current rising edge slope signal in the discharge circuit through a DC-DC current rising edge detection device and sending it to the EDM CNC controller; obtaining the discharge voltage breakdown delay signal through a breakdown delay detection circuit and sending it to the EDM CNC controller; the EDM CNC controller for receiving the monitoring signal from the detection feedback terminal, mapping the current rising edge slope signal to an output voltage signal, identifying the discharge state based on the output voltage signal and the voltage range of its own preset multi-channel discharge characteristics, determining the machining state based on the discharge state and the discharge voltage breakdown delay signal; and generating corresponding control commands to the actuator based on different machining states; the actuator includes a Z-axis servo motor and a variable frequency circulating pump for receiving the control commands from the EDM CNC controller and executing corresponding actions.
[0017] Preferably, in the breakdown delay detection circuit, the reference voltage of the voltage comparator is obtained by voltage division of a 15V standard power supply through a voltage divider resistor.
[0018] The technical solutions provided by the embodiments of the present invention can include the following beneficial effects: This application achieves accurate identification of single-channel, multi-channel and abnormal discharge states by detecting the rising edge of the discharge current and the breakdown delay of the discharge voltage, and sets different control actions for different working modes, thereby automatically achieving the purpose of increasing, decreasing or maintaining the toner concentration; it overcomes the limitations of traditional control relying on manual experience, and improves the processing stability and versatility; by autonomously generating toner and metal shavings through the reverse repair tool electrode, it increases the free electron number density of the processing fluid, promotes the transformation from single-channel discharge to multi-channel discharge, disperses the discharge energy, and realizes large-area mirror surface processing in ordinary processing fluid without the need to add external powder, thus solving the powder separation problem of mixed powder processing fluid.
[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description
[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.
[0021] Figure 1 is a flowchart illustrating a multi-channel discharge detection and control method in electrical discharge mirror finishing according to an exemplary embodiment; Figure 2 is a schematic diagram of a discharge state waveform according to another exemplary embodiment; Figure 3 is a schematic diagram of a breakdown delay detection circuit according to another exemplary embodiment; Figure 4 is a schematic diagram of a DC-DC current rising edge detection device according to another exemplary embodiment; Figure 5 is a schematic diagram of a closed-loop control framework according to another exemplary embodiment. Detailed Implementation
[0022] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.
[0023] Figure 1 is a flowchart illustrating a multi-channel discharge detection and control method in electrical discharge machining (EDM) mirror surface processing according to an exemplary embodiment. As shown in Figure 1, the method includes: S1, connecting the tool electrode to the negative terminal of a pulse power supply and the workpiece to the positive terminal of the pulse power supply; S2, detecting the current rise slope in the discharge circuit using a DC-DC current rise edge detection device and mapping it to an output voltage signal; comparing the output voltage signal with a preset voltage range of multi-channel discharge characteristics to identify the discharge state; the discharge state includes: single-channel discharge, multi-channel discharge, and abnormal discharge; S3, detecting the discharge voltage breakdown delay using a breakdown delay detection circuit, and determining the processing state based on the identified discharge state and the discharge voltage breakdown delay; the processing state includes: carbon powder accumulation... The system includes three modes: production mode, toner suppression mode, and dynamic balance mode; S4, which executes corresponding control actions according to different processing states to increase, decrease, or maintain the toner concentration; it is understood that, for ease of understanding of this application, this embodiment provides the following principle summary, specifically including: as shown in Figure 2, the discharge voltage breakdown delay is the time from the application of the discharge voltage to the start of the discharge gap until the working fluid is broken down. Under a certain discharge gap, the discharge voltage breakdown delay reflects the free electron number density in the processing fluid, indirectly reflecting the concentration of toner and metal processing chips. A very short or non-existent breakdown delay indicates a relatively high free electron number density in the processing fluid, while a long breakdown delay indicates a relatively low free electron number density in the processing fluid, which means that there are fewer conductive or low-ionization-energy powders in the processing fluid. Another physical quantity that can reflect the ease of dielectric breakdown is the rising edge of the current pulse waveform. The steeper the rising edge, the higher the free electron number density in the processing fluid, and the slower the rising edge, the lower the free electron number density in the processing fluid. Discharge voltage breakdown delay and current rising edge detection each have different advantages under different discharge processing conditions. Conclusions cannot be drawn based on just one or two pulses; rather, they must be drawn based on the statistical significance of multiple pulses. Breakdown delay detection is more sensitive but also more susceptible to interference, while current detection is more stable and reliable but has lower sensitivity and a more complex detection circuit. Therefore, this application provides a method to identify abnormal discharges, single-channel and multi-channel discharge states by monitoring the discharge voltage breakdown delay and the rising edge of the discharge current. It also utilizes the statistical probability of the machining fluid conductivity and the length of the discharge voltage breakdown delay to assist in controlling the tool lifting frequency, tool lifting height, and machining fluid circulation rate, thereby reducing the concentration of carbon powder and metal processing chips in the machining fluid. This application also proposes to achieve the pyrolysis of the EDM fluid by reworking the tool electrode to generate more carbon powder and metal processing chips. Through these measures, the control of multi-channel discharge states is achieved. The specific implementation scheme is as follows: This application proposes to rework the tool electrode by connecting it to the negative terminal of the pulse power supply and the workpiece to the positive terminal of the pulse power supply, using discharge machining conditions with high peak current and narrow pulse width to achieve the pyrolysis of mineral oil machining fluid by EDM to generate more carbon powder and metal processing chips.The electrical discharge machining conditions for rework tool electrodes avoid excessive etching of the workpiece material, with etching primarily occurring on the tool electrode side. Simultaneously, the surface finish of the tool electrode is improved through fine finishing. Measures such as increasing the tool lift frequency and height, increasing the flow rate of the machining fluid (the circulating pump uses variable frequency speed control), and lowering the working fluid temperature are used to reduce the concentration of carbon powder and metal shavings, thereby reducing the free electron number density in the working fluid.
[0024] Conductivity monitoring: A conductivity sensor is installed near the power cable on the workpiece side of the EDM machine. The closer the sensor is to the discharge position of the tool electrode and the workpiece, the better. Since the discharge gap between the tool electrode and the workpiece is very small, the conductivity sensor results are only used as an auxiliary reference for voltage and current monitoring.
[0025] Discharge voltage breakdown delay monitoring: Because the ionization time of multi-channel discharge is shorter than that of single-channel discharge, the voltage waveform of multi-channel discharge has virtually no breakdown delay or a very short breakdown delay, while the voltage waveform of single-channel discharge has a significant breakdown delay. The difference between the discharge voltage waveform of multi-channel discharge and that of short circuits and arcs is that the discharge voltage waveforms of short circuits and arcs lack high-frequency components. This can be identified through a high-frequency filter port, which is not the subject of this invention and will not be elaborated upon.
[0026] As shown in Figure 3, the discharge gap voltage signal passes through a voltage divider resistor. and The voltage divider input is fed to the negative input terminal of the voltage comparator, and the positive input terminal of the voltage comparator is connected to the comparison reference value, which is supplied by the 15V power supply. and The voltage is obtained after voltage division. The output of the voltage comparator is connected to the reset terminal of the counter. The clock terminal of the counter is connected to a fixed-frequency clock signal. The enable terminal of the counter is connected to the gate signal (GATE in Figure 2) of the pulse power supply power switch. When the discharge gap is broken down, the discharge voltage drops, the output of the voltage comparator changes from high to low, and the counter is reset to zero. The counter starts counting when the gate signal (GATE) of the pulse power supply power switch goes high and stops counting when the voltage comparator output goes low. The counter output result... Simultaneously, the inputs are fed into the input terminals of the first and second digital comparators and compared with the comparison benchmark of the first digital comparator. , , , The comparison benchmark of the second digital comparator , , , Comparison, greater than , , , When the first digital comparator outputs a high level, greater than , , , The second digital comparator outputs a high level. The output of the first digital comparator is connected to the input of the first frequency-to-voltage converter, which converts the frequency voltage into a first output signal that distinguishes between high and low voltage values. The output of the second digital comparator is connected to the input of the second frequency-to-voltage converter, and the frequency voltage is converted into a second output signal that distinguishes between high and low voltage values. First output signal This represents the result where the breakdown delay exceeds the first reference time. Second output signal. First output signal. This indicates that the breakdown delay exceeds the second reference time. First output signal. The higher the voltage value, the greater the ratio of discharge pulses whose discharge voltage breakdown delay exceeds the first reference time, and the higher the second output signal. The higher the voltage value, the greater the ratio of discharge pulses whose discharge voltage breakdown delay exceeds the second reference time.
[0027] In this embodiment, the first reference time is set at the highest point of the rising edge of the multi-channel discharge current, and the second reference time is set at the highest point of the rising edge of the single-channel discharge current. The first output signal is set accordingly. and the second output signal Comparison interval as well as When the value of the first output signal of the discharge voltage breakdown delay detection is large while the value of the second output signal of the discharge voltage breakdown delay detection is small, it indicates that there is a large amount of multi-channel discharge, which means the first output signal... Second output signal When the value of the first output signal of the discharge voltage breakdown delay detection is small and the value of the second output signal of the discharge voltage breakdown delay detection is small, it indicates that there are many short circuits and arcs, which means the first output signal... Second output signal When both the first output signal of the discharge voltage breakdown delay detection and the second output signal of the discharge voltage breakdown delay detection are large, it indicates that there is excessive discharge from a single channel, which means the first output signal... Second output signal Discharge current waveform rising edge monitoring: As shown in Figure 4, this embodiment uses a high-sensitivity current detection device based on the DC-DC power conversion principle. This device utilizes the rapid response of the DC-DC module to load changes, mapping the weak current changes in the discharge circuit to voltage fluctuations at the module output. Specifically, the detection device is connected to the discharge circuit. When discharge occurs, the discharge current excites the detection device to output a voltage signal with a specific slope (as shown in Figure 2). Because this device uses isolation diodes and pulse-gated sampling technology, it can accurately capture nanosecond-level current rising edge characteristics under strong interference environments, thus providing accurate data support for subsequent multi-channel discharge identification. Specifically, the Vin and -Vin of the DC-DC power conversion module are connected to the standard power supply Vcc (e.g., +5V) and common ground, respectively. The -Vout of the DC-DC power conversion module is connected to the detection point, which is the negative output terminal of the pulse discharge power supply. The +Vout of the DC-DC power conversion module is connected to the positive terminal of the isolation diode D1. The negative terminal of the isolation diode D1 is connected to resistor R1. The other end of resistor R1 is connected to the source (S) of the controlled switch T1. The drain (D) of the controlled switch T1 is connected to resistor R2. The other end of resistor R2 is connected to the other end of the detection point, which is the positive output terminal of the pulse discharge power supply. Thus, after the discharge gap breaks down, a very small portion of the discharge current returns to the negative output terminal of the pulse discharge power supply through resistor R2, the controlled switch T1, resistor R1, the isolation diode D1, and the DC-DC power conversion module. The larger the values of resistors R1 and R2, the smaller the current drawn from the power supply, and the less impact on the discharge processing current. However, this also requires a higher sensitivity from the DC-DC power conversion module.
[0028] The difference between -Vout and +Vout is the highest voltage value after the discharge gap breaks down.
[0029] When the discharge gap breaks down, the voltage between the positive and negative output terminals of the pulse discharge power supply will be lower than the voltage between -Vout and +Vout. This will cause the isolation diode D1 to conduct in the forward direction, which also determines that the controlled switch T1 is in the conducting state.
[0030] The gate G of the controlled switch T1 is connected to resistor R3. The other end of resistor R3 is connected to the emitter of the output transistor of the optocoupler. The collector of the output transistor of the optocoupler is connected to the standard voltage Vcc through resistor R20. The positive terminal of the LED of the optocoupler is connected to resistor R10. The other end of resistor R10 is connected to the positive terminal of the detection gate signal. The negative terminal of the LED of the optocoupler is connected to the negative terminal of the detection gate signal. The detection gate signal is taken from the gate signal of the power switch of the discharge pulse power supply.
[0031] The drain D terminal of the controlled switch T1 is connected to resistors R4 and R6 as the detection output terminal. The other end of resistor R4 is connected to the negative terminal of the first comparator, and the other end of resistor R6 is connected to the positive terminal of the second comparator.
[0032] The first and second comparators are constructed from general-purpose operational amplifiers.
[0033] The positive terminal of the first comparator is connected to resistor R5, and the other end of resistor R5 is connected to the output terminal of the first D / A digital-to-analog converter; the negative terminal of the second comparator is connected to resistor R7, and the other end of resistor R7 is connected to the output terminal of the second D / A digital-to-analog converter.
[0034] The input terminal of the first D / A digital-to-analog converter is the digital signal input value—the first reference value UD1-UD8 at the first preset time point; the input terminal of the second D / A digital-to-analog converter is the digital signal input value—the second reference value DD1-DD8 at the second preset time point.
[0035] If the voltage at the drain D point of the controlled switch T1 is higher than the first reference value at the first preset time point, the first comparator outputs a high value, indicating an abnormal discharge; if the voltage at the drain D point of the controlled switch T1 is lower than the second reference value at the second preset time point, the second comparator outputs a high value, also indicating an abnormal discharge.
[0036] The outputs of the first and second comparators are time-controlled (5μs, 15μs). The output of the first comparator is connected to the standard power supply Vcc via pull-up resistor R8. The output of the first comparator is also connected to the first input of the first AND gate. The second input of the first AND gate is connected to the output of the first monostable multivibrator (MSF). The output pulse width of the first MSF is determined by capacitor C3, resistor R14, and adjustable resistor R13, and is adjusted to 5μs. The input of the first MSF is connected to the discharge voltage breakdown edge detection signal (provided by the discharge control system of the pulse power supply and triggering the timing). The output of the second comparator is connected to the standard power supply Vcc via pull-up resistor R9. The output of the second comparator is also connected to the first input of the second AND gate. The second input of the second AND gate is connected to the output of the second MSF. The output pulse width of the second MSF is determined by capacitor C2, resistor R12, and adjustable resistor R11. The input of the second MSF is connected to the discharge voltage breakdown edge detection signal (provided by the discharge control system of the pulse power supply and triggering the timing). The first reference values UD1-UD8 and the second reference values DD1-DD8 can be obtained from actual measurements of pulse peak currents from 0.1 to 7.9 amperes in electrical discharge machining experiments and set into a table stored in a read-only memory or microcontroller.
[0037] Multi-channel discharge state identification and closed-loop control embodiment: As shown in Figure 5, this invention provides a toner concentration closed-loop control system based on current waveform characteristics. The system mainly consists of a power connection module, a detection feedback terminal (including a breakdown delay detection circuit and a current rising edge detection device), an EDM CNC controller, and actuators (Z-axis servo motor and variable frequency circulating pump). In this embodiment, to accurately capture the current change characteristics at the moment of discharge, a current rising edge detection device based on the DC-DC power conversion principle is used as a sensor. This device utilizes the physical characteristic of the DC-DC module's sensitive response to input load changes to map the current rising edge slope in the discharge loop to the voltage signal at the output. Unlike existing technologies that mainly focus on "short circuit" (extremely steep rising edge) or "open circuit" (extremely slow rising edge), this application focuses on the "intermediate slope" characteristic between the two. The controller has preset voltage ranges representing multi-channel discharge characteristics. .
[0038] When the detection device outputs voltage When the current rises too quickly, the discharge energy is concentrated, posing a risk of carbon buildup or arcing; when the output voltage of the detection device... When the current rises too slowly and the discharge channel is too simple, it means that the number density of free electrons in the processing fluid is insufficient (i.e., the toner concentration is too low); when When the discharge is complete, it is considered to be in an ideal multi-channel discharge state, at which point the processed surface will have a uniform mirror finish.
[0039] The EDM CNC controller adjusts the actuator in real time based on the signal fed back by the detection device. The specific control strategy is as follows: (1) Toner proliferation mode (for single-channel dominant state): When the signal fed back by the detection device indicates that the rising edge is too slow ( ), and the first output signal Second output signal At this point, the controller determines that the concentration of carbon powder and metal particles in the current processing fluid is insufficient to maintain the diffused discharge required for a large-area mirror surface. The controller immediately performs the following actions to accumulate particles: adjusting the tool lifting parameters: sending a command to the Z-axis servo motor to forcibly reduce the tool lifting height. to (Maintain basic venting only), and reduce the frequency of blade lifting. to The following steps may involve temporarily halting the lifting of the cutting tool. This measure aims to reduce chip removal and utilize the retention effect of discharge products between electrodes to increase the conductivity of the dielectric.
[0040] Adjusting the flushing fluid flow rate: Sending a low-frequency command to the variable frequency circulating pump to adjust the flushing fluid flow rate. Reduce to rated flow This prevents the newly generated effective toner from being washed away too quickly.
[0041] Active pyrolysis: Maintain high-frequency narrow pulse discharge, and use the reverse repair electrode to quickly pyrolyze the working fluid to generate new carbon powder to replenish the discharge gap.
[0042] (2) Toner Suppression Mode (for short circuit / arc risk conditions): When the detection device feedback signal indicates that the rising edge is too steep ( ), and the first output signal Second output signal The system determines that the particle concentration is too high. The controller then performs the opposite action: significantly increasing the blade lifting height. to And start the circulation pump at full speed (flow rate) Adjust to It utilizes the "pumping effect" and strong flushing to quickly reduce the ion concentration in the gap.
[0043] (3) Dynamic balancing mode (multi-channel processing state): When the detection signal stabilizes at... The interval, and the first output signal Second output signal The controller locks the current servo motor and water pump parameters, making only minor dynamic corrections (adjustment step size). To maintain the stability of large-area mirror processing.
[0044] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.
[0045] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.
[0046] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.
[0047] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.
[0048] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.
[0049] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.
[0050] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.
[0051] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for multi-channel discharge detection and control in electrical discharge machining of mirror surfaces, characterized in that, The method includes: connecting the tool electrode to the negative terminal of a pulse power supply and the workpiece to the positive terminal of the pulse power supply; detecting the current rise slope in the discharge circuit using a DC-DC current rise edge detection device and mapping it to an output voltage signal; comparing the output voltage signal with a preset voltage range of multi-channel discharge characteristics to identify the discharge state; the discharge state includes: single-channel discharge, multi-channel discharge, and abnormal discharge; detecting the discharge voltage breakdown delay using a breakdown delay detection circuit, and determining the processing state based on the identified discharge state and the discharge voltage breakdown delay; the processing state includes: toner proliferation mode, toner suppression mode, and dynamic balance mode; and executing corresponding control actions according to different processing states to increase, decrease, or maintain the toner concentration.
2. The method according to claim 1, characterized in that, The step of comparing the output voltage signal with a preset voltage range of multi-channel discharge characteristics to identify the discharge state includes: a preset voltage range of multi-channel discharge characteristics. If the output voltage signal of the DC-DC current rising edge detection device This indicates an abnormal discharge state; if the output voltage signal of the DC-DC current rising edge detection device... It is in a single-channel discharge state; if the output voltage signal of the DC-DC current rising edge detection device is... This indicates a multi-channel discharge state.
3. The method according to claim 2, characterized in that, The breakdown delay detection circuit includes: a discharge gap voltage signal divided by a voltage divider resistor and input to the negative input terminal of a voltage comparator; a reference voltage connected to the positive input terminal of the voltage comparator; an output terminal of the voltage comparator connected to the reset terminal of a counter; a fixed-frequency clock signal connected to the clock terminal of the counter; and an enable terminal of the counter connected to the gate signal of a pulse power supply switch. When the discharge gap breaks down, the discharge voltage drops, the output of the voltage comparator changes from high to low, and the counter is reset to zero. The counter starts counting when the gate signal of the pulse power supply switch goes high and stops counting when the output of the voltage comparator changes from high to low. The output of the counter is simultaneously input to the input terminals of a first digital comparator and a second digital comparator, and compared with the first comparison reference of the first digital comparator and the second comparison reference of the second digital comparator. When the output of the counter... When the result is greater than the first comparison reference, the first digital comparator outputs a high level; when the output result of the counter is greater than the second comparison reference, the second digital comparator outputs a high level. The output of the first digital comparator is connected to the input of the first frequency-to-voltage converter, and is converted into a first output signal that distinguishes between high and low voltage values via frequency-to-voltage conversion. The output of the second digital comparator is connected to the input of the second frequency-to-voltage converter, and is converted into a second output signal that distinguishes between high and low voltage values via frequency-to-voltage conversion. The first output signal represents the result of the breakdown delay exceeding the first reference time; the second output signal represents the result of the breakdown delay exceeding the second reference time. The higher the voltage value of the first output signal, the greater the discharge pulse ratio of the discharge voltage breakdown delay exceeding the first reference time; the higher the voltage value of the second output signal, the greater the discharge pulse ratio of the discharge voltage breakdown delay exceeding the second reference time.
4. The method according to claim 3, characterized in that, The first reference time is set at the highest point of the rising edge of the multi-channel discharge current, and the second reference time is set at the highest point of the rising edge of the single-channel discharge current.
5. The method according to claim 4, characterized in that, The step of determining the processing state based on the identified discharge state and the discharge voltage breakdown delay includes: setting a comparison interval for the first output signal. Set the comparison range of the second output signal. If it is a multi-channel discharge state, and the first output signal Second output signal The processing state is in dynamic balance mode; if it is in single-channel discharge state, and the first output signal... Second output signal The processing state is in the toner proliferation mode; if it is in the abnormal discharge state, and the first output signal Second output signal The processing state is in toner suppression mode.
6. The method according to claim 5, characterized in that, The control actions performed according to different processing states to increase, decrease, or maintain toner concentration include: if it is a toner proliferation mode, sending a command to the Z-axis servo motor through the controller to reduce the tool lifting height to a preset height range and reduce the tool lifting frequency to below a preset frequency or temporarily stop tool lifting; at the same time, sending a low-frequency command to the variable frequency circulating pump to reduce the flushing fluid flow rate to a preset percentage range of the rated flow rate; and maintaining high-frequency narrow pulse discharge to use the repair electrode to quickly decompose the working fluid and generate new toner to replenish the discharge gap.
7. The method according to claim 6, characterized in that, The process of executing corresponding control actions according to different processing states to increase, decrease or maintain toner concentration also includes: if it is toner suppression mode, sending a command to the Z-axis servo motor through the controller to raise the tool lifting height to a preset height range; at the same time sending a high-frequency command to the variable frequency circulating pump to increase the flushing fluid flow rate to the rated flow rate; and using the pump suction effect and strong flushing to reduce the ion concentration in the gap.
8. The method according to claim 7, characterized in that, The step of performing corresponding control actions according to different processing states to increase, decrease or maintain toner concentration also includes: if it is a dynamic balance mode, locking the current Z-axis servo motor and variable frequency circulating pump parameters through the controller, and making slight dynamic corrections within a preset range to stabilize mirror processing.
9. A multi-channel discharge detection and control device for electrical discharge machining of mirror surfaces, characterized in that, The device is applied to the method described in any one of claims 1-8 above. The device includes: a power connection module for connecting the tool electrode to the negative terminal of the pulse power supply and the workpiece to the positive terminal of the pulse power supply, providing discharge processing conditions with narrow pulse width and high peak current; a detection feedback terminal for detecting the current rising edge slope signal in the discharge circuit through a DC-DC current rising edge detection device and sending it to the EDM CNC controller; obtaining the discharge voltage breakdown delay signal through a breakdown delay detection circuit and sending it to the EDM CNC controller; the EDM CNC controller for receiving the monitoring signal from the detection feedback terminal, mapping the current rising edge slope signal to an output voltage signal, identifying the discharge state based on the output voltage signal and the voltage range of its own preset multi-channel discharge characteristics, and determining the processing state based on the discharge state and the discharge voltage breakdown delay signal; and also for generating corresponding control commands to the actuator based on different processing states; the actuator includes a Z-axis servo motor and a variable frequency circulating pump for receiving the control commands from the EDM CNC controller and executing corresponding actions.
10. The apparatus according to claim 9, characterized in that, In the breakdown delay detection circuit, the reference voltage of the voltage comparator is obtained by dividing the 15V standard power supply through a voltage divider resistor.