A dynamic and static process control method for discharge-driven abrasive flow machining micro-needle die

Abstract

The application discloses a kind of discharge driving abrasive flow processing microneedle die core dynamic and static process control method: S1 in the microneedle die core forming milling process, using PCD slope cutter, free abrasive liquid is added on workpiece, while programmable power supply anode is connected to microneedle die core, cathode is connected to milling cutter handle, and abrasive flow is formed in the gap between cutter and microneedle side face;Workpiece material is removed under the joint action of cutter and abrasive flow, and microneedle die core is formed;S2 effective pulse discharge energy is judged by discharge waveform, pulse discharge power is calculated and output to controller;S3 closed-loop feedback control is realized by controller during processing, and dynamic and static stability of control abrasive removal force in the gap between cutter and workpiece surface is realized.The application can effectively improve the machining precision of microneedle die core and reduce needle tip radius by controlling the processing of microneedle die core.

Description

Technical Field

[0001] This invention relates to the field of microneedle mold core manufacturing, and specifically to a dynamic and static process control method for electrical discharge driven abrasive flow machining of microneedle mold cores. Background Technology

[0002] Microneedles are an important method for transdermal drug delivery. They are tiny, elongated structures that can deliver drugs to superficial tissues below the skin surface, enabling rapid absorption and release. Currently, soluble microneedles are widely used due to their better biocompatibility. However, soluble microneedles suffer from poor penetration and inability to reach the target skin layer in practical drug delivery, primarily due to poor manufacturing quality of the microneedle core.

[0003] To enhance the performance of microneedle cores, microscale shape accuracy with smooth surfaces is required. Typically, the precision of the CNC machine tool determines the machining accuracy; however, during machining, spindle vibration, uneven material composition, and changes in the external environment can all lead to a decline in machining quality. Furthermore, these factors are uncertain during machining, and simply improving the machine tool's process parameters cannot effectively eliminate their negative impacts.

[0004] To address the manufacturing defects of microneedle cores and improve their processing quality, a discharge-driven abrasive flow process was introduced. The discharge energy significantly affects the removal force of free abrasive particles. However, due to the uncertainty of the discharge gap, the discharge energy fluctuates continuously during processing. If left uncontrolled, this can lead to excessive discharge energy, damaging the surface quality and tip of the core, or insufficient discharge energy, resulting in inadequate removal force and reduced shape accuracy of the microneedle core.

[0005] Traditional machining control schemes typically rely on professional operators to manually monitor the machining process and adjust relevant parameters in real time based on their on-site experience. This control method, which depends on manual experience, not only places high demands on the operators' professional knowledge and on-site judgment, but also suffers from significant control lag, making it difficult to achieve rapid response and precise adjustment to transient changes in the machining process. Summary of the Invention

[0006] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a dynamic and static process control method for electrical discharge driven abrasive flow machining of microneedle cores.

[0007] This invention aims to control the removal force of free abrasive particles. During the processing, considering the uncertainty of discharge energy, the discharge energy is analyzed in real time, and a suitable open-circuit voltage value is calculated by the controller to control the discharge energy and achieve high-precision micro-needle core processing.

[0008] The control method of this invention can effectively improve the processing quality of microneedle mold cores and has promising engineering applications. Its key lies in correlating discharge energy with the tip radius of the microneedle mold core, establishing the relationship between discharge power and open-circuit voltage through a database, and constructing a control model.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for controlling the dynamic and static processes of electrical discharge-driven abrasive flow machining of microneedle mold cores includes the following steps:

[0011] In the process of forming and milling microneedle cores, S1 uses a PCD slant tool to add free abrasive fluid to the workpiece. At the same time, the positive terminal of the programmable power supply is connected to the microneedle core, and the negative terminal is connected to the milling tool holder. An abrasive flow is formed in the gap between the PCD slant tool and the side of the microneedle. Under the combined action of the PCD slant tool and the abrasive flow, the workpiece material is removed to form the microneedle core.

[0012] S2 acquires the discharge waveform in real time using an oscilloscope, current sensor, and voltage sensor. It determines the effective pulse discharge energy by using the minimum threshold of the pulse discharge current; based on this, it calculates the pulse discharge power and outputs it to the controller. When the minimum discharge current threshold is not reached, it continues to receive the real-time discharge voltage and current waveforms.

[0013] During the S3 machining process, the controller implements closed-loop feedback control, aiming to minimize the combined dynamic and static deviations of the discharge power to determine the discharge control power, thereby achieving dynamic and static stability control of the abrasive removal force within the gap between the tool and the workpiece surface.

[0014] During the processing of S4, by controlling the discharge dynamic deviation to be less than 0.75 W and the discharge static deviation to be less than 0.25 W, the tip radius can be less than 4 μm, the surface can be smooth, and the scale can reach the nanometer level.

[0015] Further, in step S1, polyethylene glycol is used as the solvent and silica as the solid particles in the free abrasive slurry, and they are compounded at a mass fraction of 1~30 wt.%. After mixing and thorough stirring, the silica is uniformly distributed in the polyethylene glycol solvent, and the resulting suspension exhibits relevant shear thickening characteristics. Then, alumina abrasive particles with an average diameter of 0.3~10 μm are added to the suspension; by thorough mixing and stirring with a magnetic stirrer for 10~20 min, the alumina abrasive particles are completely dispersed in the suspension.

[0016] Furthermore, in step S1, the microneedle mold core is machined using a discharge-driven abrasive flow. On one hand, the machined surface is formed in one step through PCD milling. On the other hand, during the tool rotation, a gap exists between the metal binder and the workpiece surface. The fluid medium undergoes breakdown under the action of the electric field, releasing discharge energy during the discharge process. Under the coupling effect of discharge energy, fluid dynamic pressure, and abrasive flow velocity, the free abrasive particles perform micro-cutting on the workpiece surface, achieving secondary forming of the microneedle mold core. In discharge-driven abrasive flow machining, the free abrasive particles continuously extrude and remove from the workpiece. The normal removal force F of a single free abrasive particle... n for:

[0017] ;

[0018] Among them, F zn F is the normal force of a single free abrasive grain under dynamic pressure. e p is the average discharge removal force experienced by a single free abrasive grain. n It is the normal hydrodynamic pressure generated by the rotation of the cutting tool, d e E represents the diameter of the free abrasive grains. f m is the discharge removal energy obtained from a single free abrasive grain. a t represents the mass of a single free abrasive grain. a This refers to the discharge time.

[0019] Furthermore, in step S1, the normal removal depth h of a single free abrasive grain a The calculation is performed using the following formula:

[0020] ;

[0021] Where δ is the plastic stress of the material, v n S represents the normal initial velocity of a single free abrasive grain. n It is the normal projected area obtained after cutting by a single free abrasive grain. Calculate the normal projected area S. n The expression is as follows: ;

[0022] Furthermore, before the removal force of the free abrasive particles in step (1) is less than the tip breaking stress, the microneedle core r can be determined based on the removal depth of the free abrasive particles. d Tip radius:

[0023] ;

[0024] Where, r c The initial radius h of the microneedle tip is obtained by machining with a PCD angled tool.p The total depth of material removed from the workpiece by multiple abrasive grains, k c It is the coefficient of action of multiple free abrasive particles on the workpiece.

[0025] Furthermore, in step S1, the remaining process parameters that need to be determined during machining include: tool rotation speed, depth of feed, feed rate, abrasive particle size and concentration, and current limit value. These parameters are usually obtained through process experiments. The control system does not provide adjustment functions for these parameters, and they typically do not change during machining. Only when the control system adjusts the open-circuit voltage to the limit and still fails to meet the control requirements is it recommended to change the current limit value offline.

[0026] Furthermore, in step S2, due to the limitations of the oscilloscope, it is impossible to continuously acquire the discharge waveform. Therefore, an interval acquisition method is used instead of the continuous acquisition mode. Specifically, the acquisition interval between adjacent discharge waveforms is set to 2 seconds to ensure that the acquired waveform data can accurately reflect the core characteristics of the discharge process.

[0027] Furthermore, in step S2, the discharge power calculation must follow the parameter timing matching principle: first extract the real-time discharge current, and then synchronously obtain the discharge voltage of the corresponding timing to avoid calculation errors caused by timing mismatch.

[0028] Furthermore, in step S3, to achieve precise control of discharge power, it is necessary to pre-establish the relationship between open-circuit voltage and discharge power to clarify their dynamic mapping relationship. This function is obtained by fitting multiple sets of process experimental data: first, discharge experiments with different open-circuit voltage input conditions are designed, and the corresponding discharge power data under each condition are collected; then, the experimental data are processed through a data fitting algorithm to obtain the function.

[0029] Furthermore, in step S3, in order to achieve quantitative analysis of the performance and control effect of the control system, as well as evaluation of the discharge power fluctuation and control accuracy, discharge dynamic deviation and discharge static deviation are introduced for characterization. The discharge dynamic deviation reflects the degree of fluctuation and stability of the pulse discharge power during the processing, and is obtained from the standard deviation of the pulse discharge power during the control process. The discharge static deviation is used to characterize the steady-state control accuracy of the control system, and is obtained from the difference between the average pulse discharge power and the target power.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] Through the rotation of the tool and the discharge between the tool and the workpiece, the free abrasive particles generate a certain impact force to perform micro-cutting on the surface of the workpiece, realizing secondary removal of the surface of the micro needle mold core; the free abrasive particles driven by the discharge can not only remove the burrs left after the first machining by the tool and reduce the residual stress on the surface of the mold core, but also significantly reduce the tip radius of the micro needle mold core, realizing high-precision micro needle mold core machining.

[0032] By constructing a microneedle core processing control system based on discharge energy and employing a PID control algorithm, the discharge energy can be adjusted in real time during processing, thereby controlling the removal force of free abrasive particles. This method requires no external intervention, possesses high adaptability, and further reduces the tip radius of the microneedle core. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of micro-needle mold cores being machined using ultra-precision machine tools.

[0034] Figure 2 A schematic diagram of microneedle core machining using electrical discharge driven abrasive flow.

[0035] Figure 3 This is a model diagram of the control system for the microneedle core machining process.

[0036] Figure 4 This is a diagram showing the device composition of the control system for the micro-needle mold core machining process. In the diagram, A represents the abrasive fluid, and B represents the workpiece.

[0037] Figure 5 This is a diagram of the control interface of the microneedle mold core processing control system.

[0038] Figure 6 This is a waveform diagram of the discharge during the microneedle core processing.

[0039] Figure 7 This is a graph showing the analysis of open-circuit voltage and discharge power during the microneedle core machining process.

[0040] Figure 8 This is an analysis diagram of the target power and discharge characteristics during the microneedle core fabrication process.

[0041] Figure 9 This is a comparison chart showing the difference between microneedle mold cores with and without processing control.

[0042] Appendix Figure 1-2 In the middle: 1. Polycrystalline diamond; 2. Mechanical end jump; 3. Passivation; 4. Fracture; 5. Cobalt binder; 6. Rotary shaft; 7. Microneedle tip; 8. Free abrasive particles; 9. Solid particles. Detailed Implementation

[0043] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0044] A method for controlling the dynamic and static processes of electrical discharge-driven abrasive flow machining of microneedle mold cores can be implemented through the following steps:

[0045] In the milling process of microneedle core forming, S1 uses a PCD slant tool. Free abrasive fluid is added to the workpiece, and the positive terminal of the programmable power supply is connected to the microneedle core, while the negative terminal is connected to the milling tool holder. An abrasive flow is formed in the gap between the tool and the side of the microneedle. Under the combined action of the tool and the abrasive flow, the workpiece material is removed to form the microneedle core. The slant in PCD slant tool refers to the inclination of the side of the PCD tool, and the inclination angle is consistent with the angle of the microneedle core to be machined.

[0046] S2 acquires the discharge waveform in real time using an oscilloscope, current sensor, and voltage sensor. It determines the effective pulse discharge energy by using the minimum threshold of the pulse discharge current; based on this, it calculates the pulse discharge power and outputs it to the controller. When the minimum discharge current threshold is not reached, it continues to receive the real-time discharge voltage and current waveforms.

[0047] During the S3 machining process, the controller implements closed-loop feedback control, aiming to minimize the combined dynamic and static deviations of the discharge power to determine the discharge control power, thereby achieving dynamic and static stability control of the abrasive removal force within the gap between the tool and the workpiece surface.

[0048] During the processing of S4, by controlling the discharge dynamic deviation to be less than 0.75 W and the discharge static deviation to be less than 0.25 W, the tip radius can be less than 4 μm, the surface can be smooth, and the scale can reach the nanometer level.

[0049] Figure 1 This diagram illustrates the machining of microneedle cores using ultra-precision machine tools. The microneedle cores are formed using a PCD (Polymerized Calculation) angled tool. However, due to the large depth-to-width ratio and extremely small tip size of the microneedle structure, under conditions of large total depth of cut, external environmental influences can easily induce mechanical vibration between the tool and the workpiece, generating unstable cutting forces during the cutting process. Simultaneously, the rotational runout of the tool itself further exacerbates the periodic excitation effect of the vibration, leading to defects such as tip dulling, microcracks, and even fracture. These defects are difficult to completely avoid in traditional machining systems. Therefore, a method for machining microneedle cores using a composite assisted process of electrical discharge-driven abrasive flow is proposed, such as... Figure 2 As shown, on the one hand, the machined surface is formed in one step by milling with a PCD inclined milling tool. On the other hand, during the tool rotation, a gap exists between the metal binder and the workpiece surface, and the fluid medium undergoes breakdown under the action of an electric field, releasing discharge energy during the discharge process. Under the coupling effect of discharge energy, fluid dynamic pressure, and abrasive flow velocity, the free abrasive particles perform micro-cutting on the workpiece surface, realizing the secondary forming of the micro-needle mold core. In discharge-driven abrasive flow machining, the free abrasive particles continuously squeeze and remove the workpiece, wherein the normal removal force F of a single free abrasive particle is... n for:

[0050] ;

[0051] Among them, F zn F is the normal force of a single free abrasive grain under dynamic pressure. e p is the average discharge removal force experienced by a single free abrasive grain. n It is the normal hydrodynamic pressure generated by the rotation of the cutting tool, d e E represents the diameter of the free abrasive grains. f m is the discharge removal energy obtained from a single free abrasive grain. a t represents the mass of a single free abrasive grain. a This refers to the discharge time.

[0052] Furthermore, the normal removal depth h of a single free abrasive grain a The calculation is performed using the following formula:

[0053] ;

[0054] Where δ is the plastic stress of the material, v n S represents the normal initial velocity of a single free abrasive grain. n It is the normal projected area obtained after cutting by a single free abrasive grain. Calculate the normal projected area S. n The expression is as follows:

[0055] ;

[0056] Furthermore, before the removal force of the free abrasive particles is less than the tip destructive stress, the microneedle core r can be determined based on the removal depth of the free abrasive particles. d Tip radius:

[0057] ;

[0058] Where, r c The initial radius h of the microneedle tip is obtained by machining with a PCD angled tool. p It is the total depth removed from the workpiece by the action of multiple abrasive grains, k c It is the coefficient of action of multiple free abrasive particles on the workpiece.

[0059] Figure 3The diagram illustrates the control system. In the electro-discharge driven abrasive flow machining of microneedle cores, the surface and tip shape of the microneedle core are first constructed by cutting the workpiece with a tool. Then, secondary shaping is achieved through the flexible removal of free abrasive particles. The first step requires installing the required workpiece and tool in place. The initial machine tool process parameters include: tool rotation speed, feed rate, abrasive particle size and concentration. The required discharge parameters include: current limit value, and initial target power for control.

[0060] The second step is to construct a PID control system based on discharge energy. The PID control system utilizes the proportional parameter K. p Integral parameter K i and differential parameter K d A linear combination of these parameters forms a control output based on the target deviation, thereby achieving target control. The corresponding control system is primarily implemented on a workstation and developed using MATLAB software. The theoretical model of the PID control system is as follows:

[0061] ;

[0062] Where u(t) is the control output, K p K is a proportional parameter. i K is the integration parameter. d Let t be the differential parameter, and e(t) be the real-time deviation of the control system.

[0063] The third step involves acquiring real-time discharge signals during the processing using current and voltage sensors. These signals are then filtered to remove noise, allowing for the determination of the maximum instantaneous discharge current and whether pulsed discharge is satisfied. When the pulsed discharge current exceeds a minimum threshold, the real-time discharge power is calculated. A PID controller is then used to determine the optimal open-circuit voltage and adjust the output, resulting in a more stable processing procedure.

[0064] It should be further explained that, due to the limitations of the oscilloscope, continuous acquisition of discharge waveforms is not possible. Therefore, an interval acquisition method is used instead of continuous acquisition. Specifically, the acquisition interval between adjacent discharge waveforms is set to 2 seconds to ensure that the acquired waveform data accurately reflects the core characteristics of the discharge process.

[0065] This invention Figure 4 The intermediate machining tools are three-axis high-precision Multi Pro IV CNC machine tools manufactured by Takashima Sangyo of Japan.

[0066] Figure 4 This is a diagram showing the setup of the platform for the microneedle mold core processing. Its complete control system includes:

[0067] The signal acquisition section mainly includes oscilloscopes, current sensors, voltage sensors, etc.

[0068] The machining process mainly includes machine tools, cutting tools, and workpieces;

[0069] The discharge section mainly includes a programmable power supply, wires, etc.

[0070] The control and decision-making component mainly includes workstations and related supporting software.

[0071] The platform is set up as follows: First, the cutting tool and workpiece are mounted on the machine tool, and the workpiece is leveled and the tool is set, followed by the addition of the prepared abrasive flow. Next, the discharge section is installed, with the positive terminal of the programmable power supply connected to the workpiece via a wire, and the negative terminal connected to the fixture via a wire to form a circuit. Then, a current sensor, voltage sensor, and oscilloscope are connected to the circuit to collect the discharge signal. Finally, the workstation is connected to the programmable power supply and oscilloscope for communication, and the relevant control system algorithm is written on the workstation to achieve intelligent control of the micro-needle mold core machining process.

[0072] Figure 5 This document describes the software interface for the microneedle mold core machining process control system, written in MATLAB. The software interface allows for better monitoring of the machining process and timely adjustment of relevant parameters. The design primarily utilizes the GUI Design Environment module in MATLAB, which includes control parameter input, signal process monitoring, and output result display. The control parameter input includes input of target power and PID gain parameters. The process monitoring mainly includes real-time display of the discharge waveform and cumulative display of pulse discharge power. The output result display includes real-time numerical display of discharge power, output open-circuit voltage, and discharge count. Furthermore, the software integrates start / stop functions for the control system, making the entire system operation more convenient.

[0073] Figure 6 This describes the discharge characteristics during the processing. During discharge, if the current exceeds the set current limit, it causes a voltage drop, primarily due to the mode switching of the programmable power supply during discharge. When discharge occurs, the programmable power supply switches from constant voltage mode to constant power mode to protect the circuit and ensure energy stability.

[0074] To obtain the transfer function of the control system, it is necessary to obtain the relationship between different open-circuit voltages and pulse discharge power, such as... Figure 7As shown in the figure, experiments demonstrate that the pulse power increases with increasing open-circuit voltage. This indicates that pulse discharge power can effectively characterize the changes in discharge characteristics and open-circuit voltage during pulse discharge.

[0075] Figure 8 The graph shows the changes in discharge dynamic deviation and discharge static deviation under different target power. It can be seen that when the target power is 1.75W, both discharge dynamic deviation and discharge static deviation reach their lowest values, at which point the control system performance reaches its optimal level.

[0076] Figure 9 The image shows a comparison of the microneedle core machining results with and without process control at a target power of 1.75W. It can be seen that compared with no control, using this method increases the tip radius of the microneedle core and improves the machining accuracy of the microneedle core.

[0077] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the dynamic and static processes of electrical discharge driven abrasive flow machining of microneedle cores, characterized in that: Includes the following steps: S1 uses a discharge-driven abrasive flow to process microneedle mold cores: a PCD slanted tool is used, free abrasive fluid is added to the workpiece, and the positive terminal of the programmable power supply is connected to the microneedle mold core, while the negative terminal is connected to the milling cutter shank. An abrasive flow is formed in the gap between the PCD slanted tool and the side of the microneedle mold core. Under the combined action of the PCD slanted tool and the abrasive flow, the workpiece material is removed to form the microneedle mold core. S2 acquires the discharge waveform during the micro-needle core forming and milling process in step S1 in real time using an oscilloscope, current sensor, and voltage sensor. The effective pulse discharge energy is determined by the minimum threshold of the pulse discharge current. Based on this, the pulse discharge power is calculated and output to the controller. If the minimum threshold of the discharge current is not reached, the waveforms of the real-time discharge voltage and current continue to be received. S3 During the micro-needle core forming and milling process in step S1, the controller implements closed-loop feedback control, and determines the discharge control power with the goal of minimizing the combined dynamic and static deviations of the discharge power, so as to control the dynamic and static stability of the abrasive removal force in the gap between the tool and the workpiece surface.

2. The dynamic and static process control method for discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: The free abrasive slurry in step S1 uses polyethylene glycol as a solvent and silica as a solid particle, and is compounded at a mass fraction of 1~30 wt.%; after mixing and thorough stirring, the silica is uniformly distributed in the polyethylene glycol solvent to form a suspension with shear thickening properties. Then, alumina abrasive particles with an average diameter of 0.3~10 μm are added to the suspension; the alumina abrasive particles are thoroughly mixed and stirred with a magnetic stirrer for 10~20 min to achieve complete dispersion in the suspension.

3. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: In step S1, during the machining of the microneedle core using a discharge-driven abrasive flow, the surface is first milled using a PCD (Polymer Die Cutter) to achieve a one-time forming. Secondly, during the rotation of the PCD cutter, a gap exists between the metal binder and the workpiece surface. The fluid medium undergoes breakdown under the influence of the electric field, releasing discharge energy during the discharge process. Under the coupling effect of discharge energy, fluid dynamic pressure, and abrasive flow velocity, the free abrasive particles perform micro-cutting on the workpiece surface, achieving a secondary forming of the microneedle core. In the discharge-driven abrasive flow machining, the free abrasive particles continuously extrude and remove material from the workpiece. The normal removal force F of a single free abrasive particle... n for: (1)； In the formula: F zn The normal force of a single free abrasive grain under dynamic pressure; F e The average discharge removal force experienced by a single free abrasive grain; p n It is the normal hydrodynamic pressure generated by the rotation of the cutting tool; d e The diameter of the free abrasive grains; E f Energy is removed by discharge from a single free abrasive grain; m a The mass of a single free abrasive grain; t a This refers to the discharge time.

4. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: The normal removal depth h of a single free abrasive grain in the free abrasive slurry in step S1 a The calculation is performed using the following formula: ； In the formula: δ represents the plastic stress of the material; v n The initial normal velocity of a single free abrasive grain; S n It is the normal projected area obtained after cutting by a single free abrasive grain. Calculate the normal projected area S. n The expression is as follows: 。 5. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: Before the removal force of the free abrasive particles in step S1 is less than the tip breaking stress, the microneedle core r can be determined based on the removal depth of the free abrasive particles. d Tip radius: ； In the formula: r c The initial radius of the microneedle tip is obtained by machining with a PCD angled tool. h p It is the total depth of material removed from the workpiece by the action of multiple abrasive grains; k c It is the coefficient of action of multiple free abrasive particles on the workpiece.

6. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: In step S2, the discharge waveform is taken at 2-second intervals. The obtained discharge signal waveform needs to be filtered first. When the discharge current is greater than the minimum threshold of the pulse discharge current, the real-time discharge power is calculated, and the pulse discharge power to be adjusted is calculated by the PID controller.

7. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: In step S3, the controller implements closed-loop feedback control. During control, a database of processing logic is established based on the correlation between pulse discharge power and open-circuit voltage. The open-circuit voltage U of the programmable power supply is calculated using this database. p It also adjusts the pulse discharge power in real time to complete closed-loop feedback control.

8. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: In step S3, to achieve quantitative analysis of controller performance and control effect, as well as evaluation of discharge power fluctuation and control accuracy, discharge dynamic deviation and discharge static deviation are introduced for characterization. The discharge dynamic deviation reflects the degree of fluctuation and stability of pulse discharge power during processing and is obtained from the standard deviation of pulse discharge power during control. The discharge static deviation is used to characterize the steady-state control accuracy of the control system and is obtained from the difference between the average pulse discharge power and the target power.

9. The method for controlling the dynamic and static processes of discharge-driven abrasive flow machining of microneedle cores according to claim 1, characterized in that: In step S3, by controlling the discharge dynamic deviation to be less than 0.75 W and the discharge static deviation to be less than 0.25 W, the tip radius is less than 4 μm, the surface is smooth, and the scale reaches the nanoscale.

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