Micro-electrochemical machining method and device

Abstract

The present application relates to the technical field of electrolytic machining, and more particularly to a micro-electrolytic machining method and device, comprising S1, selecting a tubular tool electrode as a cathode, making it work liquid-wettable through surface modification treatment; S2, providing a workpiece as an anode, making it work liquid-repellent through surface modification treatment; S3, fixing the workpiece, adding a constraint liquid to the liquid tank until the workpiece is completely covered, and then adding a work liquid on the constraint liquid to cover it; S4, connecting the tubular tool electrode with a liquid storage cylinder, installing it on a machining tool, making the liquid outlet end perpendicular to the workpiece, and determining the machining gap; S5, opening the liquid storage cylinder to input the work liquid, which flows out of the liquid outlet end, contacts the workpiece, and then flows out of the workpiece surface along the outer wall surface of the tubular tool electrode; S6, connecting the tubular tool electrode, the workpiece, and the power supply; S7, turning on the power supply, cooperating with the machining tool, and moving the tubular tool electrode according to the preset trajectory. The present application improves the machining localization and machining precision in the electrolytic machining process.

Description

Technical Field

[0001] This invention relates to the technical field of electrolytic machining, and more specifically, to a micro-electrolytic machining method and apparatus. Background Technology

[0002] With the continuous advancement of technology, micromachining technology is increasingly widely used in high-precision fields, especially in industries such as microelectronics, medical devices, precision machinery, and optical components. Existing micromachining methods, such as micromachining, microlaser machining, and microelectrodisiac machining, while meeting micrometer-level precision requirements, are often limited by factors such as mechanical stress, recast layers, and uneven tool wear, leading to a decrease in accuracy. In contrast, electrochemical machining, as a high-precision, non-contact, and heat-affected zone-free machining method, is gradually becoming an important approach to solving these problems.

[0003] Microjet electrochemical machining (MSM) uses a metal electrode as the cathode and ejects a working fluid in jet form through a nozzle, which then contacts the workpiece surface. After voltage is applied, the working fluid removes material through an electrochemical reaction between the tool electrode and the workpiece. Due to its superior machining accuracy and process flexibility, MSM is widely used in manufacturing high-surface-quality, complex geometries, and high-precision microstructures. However, current microjet electrochemical machining methods still have limitations in terms of machining localization. For example, Chinese patent CN112975011A discloses a highly localized microgroove electrochemical machining device and method, which uses a high-density insoluble insulating liquid to constrain the working fluid jet in real time to improve the localization of microgroove electrochemical machining. Although this method improves the localization of electrochemical machining to some extent, the mechanism by which the working fluid exits the machining area is not yet fully understood. If the tool electrode is not properly selected or the machining surface is not suitable for difficult-to-machine materials with good wettability, the working fluid will diffuse in the machining area, causing uneven current distribution, leading to stray corrosion and decreased machining accuracy. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the diffusion of working fluid in the processing area causing uneven current distribution, which leads to decreased processing accuracy and stray corrosion. This invention provides a micro-electrochemical machining method and apparatus to improve the localization and accuracy of micro-electrochemical machining, thereby enabling the machining of microstructures on difficult-to-machine materials.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A micro-electrochemical machining method is provided, comprising the following steps:

[0007] S1. Select a tubular tool electrode as the cathode, and perform surface modification treatment on the tubular tool electrode to make its outer wall surface have working fluid affinity properties.

[0008] S2. Provide a workpiece as an anode, and perform surface modification treatment on the workpiece to give its surface the properties of being hydrophobic to the working fluid;

[0009] S3. Fix the workpiece at the bottom of the liquid tank, add constraint liquid to the liquid tank until the liquid level of the constraint liquid is higher than the surface of the workpiece, and then add working liquid until the working liquid covers the liquid level of the constraint liquid. The density of the constraint liquid is greater than the density of the working liquid and the constraint liquid is an insulating liquid that is immiscible with the working liquid.

[0010] S4. Connect the tubular tool electrode to a reservoir containing working fluid, and make the outlet end of the tubular tool electrode perpendicular to the surface of the workpiece.

[0011] S5. Open the liquid storage tank to input working fluid into the tubular tool electrode, and the working fluid flows out from the liquid outlet.

[0012] S6. Connect the tubular tool electrode to the negative terminal of the power supply, and connect the workpiece to the positive terminal of the power supply;

[0013] S7. Turn on the power and use a machine tool to control the movement trajectory of the tubular tool electrode, thereby performing micro-electrolytic machining on the surface of the workpiece.

[0014] The micro-electrochemical machining method of this invention utilizes the working fluid-affinity properties of the outer wall of a tubular tool electrode and the working fluid-repellency properties of the workpiece surface during electrochemical machining of microstructures. This achieves high localization when the working fluid jet is in a confined fluid environment. First, the surface of the tubular tool electrode is modified to be fluid-affinity, and the surface of the workpiece is modified to be fluid-repellency. During machining, the workpiece is fixed to the bottom of the liquid tank using a fixture. Then, confined fluid and working fluid are added sequentially to cover the workpiece. The tubular tool electrode is then connected to a reservoir, ensuring the outlet is perpendicular to the workpiece. After opening the reservoir, the working fluid flows out from the tubular tool electrode. The positive and negative terminals of the power supply are then connected to the workpiece and the tubular tool electrode, respectively. After turning on the power, the relative position between the tubular tool electrode and the workpiece is controlled by the machine tool to achieve high-precision machining. In micro-electrochemical machining, the workpiece surface is covered with a layer of confining fluid. This confining fluid is immiscible with the working fluid and provides insulation, protecting non-machining areas from corrosion. When the working fluid is ejected through the tubular tool electrode, it first breaks through the confining fluid layer and contacts the workpiece surface; this area is the machining zone. Because the working fluid's density is less than the confining fluid, it flows upwards. At this point, the working fluid simultaneously contacts both the tool electrode and the workpiece surface. Due to the significant difference in wettability between the two surfaces, the working fluid forms different contact angles on the two surfaces, resulting in a tension imbalance. This imbalance generates a Young's force, making the working fluid more likely to flow in the direction of greater wettability. Therefore, after flowing out of the tool electrode, the working fluid flows upwards along the electrode surface and hardly spreads on the workpiece surface. In this way, the machining zone is very small, while the non-machining area is protected by the confining fluid, significantly improving the localization of machining and thus enhancing the machining accuracy of micro-pits, micro-grooves, and other microstructures.

[0015] Preferably, after the surface modification treatment, the tubular tool electrode has a contact angle range of 10°-40°; after the surface modification treatment, the workpiece has a contact angle range of 120°-150°. The contact angle refers to the angle between the boundary of the liquid-solid contact area and the liquid surface when a liquid comes into contact with a solid surface. It reflects the wettability of the liquid on the solid surface. When the contact angle is greater than 0° and less than 90°, the solid surface is hydrophilic; when the contact angle is 90°, the solid surface is neutral; when the contact angle is greater than 90° and less than 180°, the surface is hydrophobic. After the surface modification treatment, the tubular tool electrode has a contact angle less than 90° and is hydrophilic; after the surface modification treatment, the workpiece has a contact angle greater than 90° and is hydrophobic, thereby reducing the flow area formed by the working fluid on the workpiece surface and improving machining localization.

[0016] Preferably, in step S1, the surface modification treatment of the tubular tool electrode is performed by: machining a micro / nano structure with working fluid affinity on the outer wall surface, or coating it with a working fluid affinity coating. The tubular tool electrode has a hollow structure, facilitating the flow of working fluid from the tube. To ensure that the working fluid can flow upwards along the tubular tool electrode and avoid forming a large flow area on the workpiece surface causing stray corrosion, surface modification treatment is required. Applying a specific coating or machining a micro / nano structure can both impart working fluid affinity properties, thereby improving machining accuracy.

[0017] Preferably, the micro / nano structure fabrication process with working fluid affinity includes immersing the outlet end in concentrated sulfuric acid, allowing it to stand, and then rinsing the tubular tool electrode with clean water. The strong acidity of concentrated sulfuric acid corrodes the electrode surface, causing it to gradually dissolve or form tiny pits and pores. During immersion, the uneven corrosion of the electrode surface by the concentrated sulfuric acid leads to the formation of micron- or nano-scale rough structures. This rough structure increases the surface area of ​​the electrode and gives it higher surface energy, thereby enhancing the electrode's wettability to the working fluid. Immersing in concentrated sulfuric acid for a period of time and then rinsing with clean water avoids excessive corrosion.

[0018] Preferably, the immersion depth of the outlet end in concentrated sulfuric acid is 0.8cm-1.2cm, and the immersion time is 8min-12min. During processing, only the micro / nano structure needs to be etched at the outlet end; therefore, the immersion depth needs to be controlled. Simultaneously, the immersion time directly determines the degree of corrosion of the tubular tool electrode by concentrated sulfuric acid. It is necessary to ensure that the micro / nano structure compatible with the working fluid is etched, while avoiding excessive corrosion that could damage the structure of the tubular tool electrode.

[0019] Preferably, in step S2, the surface modification treatment of the workpiece is performed by coating it with a coating that has the properties of repelling working fluid. By coating a specific coating, the surface of the workpiece is made to have the properties of repelling working fluid, thereby reducing the lateral diffusion range of the working fluid on the workpiece surface and improving the localization of micro-electrochemical machining.

[0020] Preferably, the coating with hydrophobic properties is applied by immersing the workpiece in a fluorosilane solution, allowing it to stand, and then drying the workpiece. By immersing the workpiece in the fluorosilane solution, a thin fluorosilane film is formed on the workpiece surface. Fluorosilane is a compound containing fluorine and silicon; its fluoroalkyl group in its molecular structure gives it extremely strong hydrophobic properties. Once the fluorosilane molecular film forms, it effectively reduces the surface energy of the workpiece, making it difficult for the working fluid to spread and wet the workpiece surface, thus achieving the hydrophobic effect. Furthermore, the fluorosilane molecular film also has good adhesion and stability, maintaining the hydrophobic properties of the workpiece for a long time.

[0021] Preferably, in step S3, the difference between the height of the constraint fluid level and the height of the workpiece surface is 0.5mm-1mm. The coverage height of the constraint fluid on the workpiece surface should be adaptively adjusted according to the diameter of the tubular tool electrode. When the outer diameter of the tubular tool electrode is small, the coverage height of the constraint fluid should be appropriately reduced to ensure the stability of the flow channel formed by the working fluid on the tool electrode surface.

[0022] Preferably, in step S4, the distance between the liquid outlet and the workpiece surface is 50μm-200μm. Maintaining a small, perpendicular distance between the liquid outlet of the tubular tool electrode and the workpiece surface helps to precisely control the electrolytic reaction zone, reduce stray corrosion, and improve machining accuracy. However, a smaller distance is not always better; a certain gap is needed to allow the working fluid to flow evenly, carry away reaction products, prevent accumulation, ensure machining stability, and simultaneously aid in heat dissipation, reducing workpiece thermal deformation and thermal damage, and ensuring machining quality.

[0023] The present invention also provides a micro-electrochemical machining apparatus, comprising a workpiece, a tubular tool electrode, a machine tool, a liquid supply system, and a power supply. The machine tool includes an X / Y axis moving platform and a Z axis moving platform. The liquid supply system includes an injection pump and a liquid reservoir. The liquid reservoir is mounted on the Z axis moving platform, with one end connected to the injection pump and the other end connected to the tubular tool electrode. The X / Y axis moving platform is provided with a liquid tank for holding a constraint fluid and a working fluid. A fixture for fixing the workpiece is provided in the liquid tank. The tubular tool electrode is perpendicular to the workpiece. The negative terminal of the power supply is connected to the tubular tool electrode, and the positive terminal of the power supply is connected to the workpiece.

[0024] The micro-electrochemical machining apparatus of the present invention first uses a fixture to fix the workpiece at the bottom of the liquid tank. Then, a constraint liquid and a working liquid are added to the liquid tank. The injection pump is turned on to spray the working liquid in the storage tank from the tubular tool electrode to form a working liquid jet. The power is turned on, and the tubular tool electrode connected to the negative electrode is used as the cathode, and the tubular tool electrode connected to the positive electrode is used as the anode. The relative position between the tubular tool electrode and the workpiece is controlled by the Z-axis moving platform and the X / Y-axis moving platform to precisely control the micro-electrochemical machining position. This achieves highly localized machining of microgrooves of different shapes and provides strong process flexibility.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Improved the localization and precision of micro-electrochemical machining, thereby enabling the machining of microstructures such as micro-pits and micro-grooves on difficult-to-machine materials;

[0027] 2. By performing surface modification treatment on the tubular tool electrode and the workpiece, the lateral diffusion flow range of the working fluid on the workpiece surface is reduced.

[0028] 3. The three-axis moving platform precisely controls the machining position, enabling highly localized machining of microgrooves of different shapes and providing strong process flexibility. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the micro-electrochemical machining method;

[0030] Figure 2 This is a schematic diagram of the structure of a micro-electrochemical machining device;

[0031] Figure 3 A schematic diagram showing the contact angle between an untreated tubular tool electrode and the working fluid;

[0032] Figure 4 This is a schematic diagram showing the contact angle between the surface-modified tubular tool electrode and the working fluid.

[0033] Figure 5 A schematic diagram of the microstructure of an untreated tubular tool electrode;

[0034] Figure 6 This is a schematic diagram of the microstructure of the tubular tool electrode after surface modification treatment;

[0035] Figure 7 This is a schematic diagram showing the contact angle between the untreated workpiece and the working fluid.

[0036] Figure 8 This is a schematic diagram showing the contact angle between the surface-modified workpiece and the working fluid.

[0037] Figure 9 This is a schematic diagram of the flow field simulation area;

[0038] Figure 10 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 90° and the contact angle of the workpiece surface is 90°;

[0039] Figure 11 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 10° and the contact angle of the workpiece surface is 90°;

[0040] Figure 12 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 20° and the contact angle of the workpiece surface is 90°;

[0041] Figure 13 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 40° and the contact angle of the workpiece surface is 90°;

[0042] Figure 14 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 20° and the contact angle of the workpiece surface is 120°;

[0043] Figure 15 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 20° and the contact angle of the workpiece surface is 135°.

[0044] Figure 16 This is a flow field simulation diagram when the contact angle of the tubular tool electrode surface is 20° and the contact angle of the workpiece surface is 150°.

[0045] In the attached diagram: 100, workpiece; 200, tubular tool electrode; 300, machine tool; 310, X / Y axis moving platform; 311, liquid tank; 312, fixture; 320, Z axis moving platform; 410, injection pump; 420, liquid reservoir; 500, power supply; 600, constraint fluid; 700, working fluid. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0047] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0048] Example 1

[0049] This embodiment is the first embodiment of a micro-electrochemical machining method, including the following steps:

[0050] S1. Select the tubular tool electrode 200 as the cathode and perform surface modification treatment on the tubular tool electrode 200 to make its outer wall surface have the property of being compatible with the working fluid 700.

[0051] S2. Provide workpiece 100 as an anode, and perform surface modification treatment on workpiece 100 to give its surface the properties of working fluid 700.

[0052] S3. Fix the workpiece 100 at the bottom of the liquid tank 311, add constraint liquid 600 to the liquid tank 311 until the liquid level of constraint liquid 600 is higher than the surface of workpiece 100, and then add working liquid 700 until the working liquid 700 covers the liquid level of constraint liquid 600. The density of constraint liquid 600 is greater than the density of working liquid 700 and constraint liquid 600 is an insulating liquid that is immiscible with working liquid 700.

[0053] S4. Connect the tubular tool electrode 200 to the reservoir 420 containing the working fluid 700, and make the outlet end of the tubular tool electrode 200 perpendicular to the surface of the workpiece 100.

[0054] S5. Open the liquid storage tank 420 to input the working fluid 700 into the tubular tool electrode 200. The working fluid 700 flows out from the outlet end.

[0055] S6. Connect the tubular tool electrode 200 to the negative terminal of the power supply 500, and connect the workpiece 100 to the positive terminal of the power supply 500.

[0056] S7. Turn on the power supply 500 and use the machine tool 300 to control the movement trajectory of the tubular tool electrode 200, thereby performing micro-electrolytic machining on the surface of the workpiece 100.

[0057] The micro-electrochemical machining method in this embodiment utilizes the affinity of the working fluid 700 on the outer wall of the tubular tool electrode 200 and the repellency of the working fluid 700 on the surface of the workpiece 100 during the electrochemical machining of microstructures. When the working fluid 700 jet is in a confining fluid 600 environment, high localization machining is achieved. First, the surface of the tubular tool electrode 200 is modified to possess the affinity for the working fluid 700, and the surface of the workpiece 100 is modified to possess the repellency of the working fluid 700. For example... Figure 1 , Figure 2 As shown, during the machining process, the workpiece 100 is fixed to the bottom of the liquid tank 311 by the fixture 312, and then the constraint liquid 600 and working liquid 700 are added in sequence to cover it. Then, the tubular tool electrode 200 is connected to the liquid storage tank 420, and the liquid outlet end is ensured to be perpendicular to the workpiece 100. After the liquid storage tank 420 is opened, the working liquid 700 flows out from the tubular tool electrode 200. Then, the positive and negative terminals of the power supply 500 are connected to the workpiece 100 and the tubular tool electrode 200 respectively. After the power supply 500 is turned on, the relative position between the tubular tool electrode 200 and the workpiece 100 is controlled by the machining tool 300 to achieve high-precision machining.

[0058] During micro-electrochemical machining, a layer of constraint fluid 600 covers the surface of workpiece 100. When working fluid 700 is ejected through the tubular tool electrode 200, it first breaks through the constraint fluid 600 layer and contacts the surface of workpiece 100. Because the density of working fluid 700 is less than that of constraint fluid 600, working fluid 700 flows upward. At this time, working fluid 700 is in contact with both the tool electrode and the surface of workpiece 100. Due to the significant difference in wettability between the two surfaces, working fluid 700 forms different contact angles on the two surfaces, resulting in an imbalance of tension between the working fluid 700 and the tool electrode. This imbalance generates a Young's force, making it easier for working fluid 700 to flow in the direction of greater wettability. Therefore, after flowing out of the tool electrode, working fluid 700 flows upward along the electrode surface and hardly spreads on the surface of workpiece 100. In this way, the flow area formed by the working fluid 700 on the surface of the workpiece 100 is very small, while the rest is protected by the confining fluid 600, which significantly improves the localization of the machining and thus improves the machining accuracy of micro-pits, micro-grooves and other micro-structures.

[0059] In this embodiment, the tubular tool electrode 200, after the surface modification treatment, has a contact angle range of 10°-40°; the workpiece 100, after the surface modification treatment, has a contact angle range of 120°-150°. The contact angle refers to the angle between the boundary of the liquid-solid contact area and the liquid surface when a liquid comes into contact with a solid surface. The contact angle is usually described using Young's equation, and its mathematical expression is as follows:

[0060]

[0061] In the formula, θ is the liquid contact angle, and γ sL1 γ sL2 and γ L1L2 These are the surface tensions at the solid-working fluid interface, the solid-constraint fluid interface, and the working fluid-constraint fluid interface, respectively.

[0062] It reflects the wettability of a liquid on a solid surface. When the contact angle is greater than 0° and less than 90°, the solid surface is hydrophilic; when the contact angle is 90°, the solid surface is neutral; and when the contact angle is greater than 90° and less than 180°, the surface is hydrophobic. After surface modification treatment, the tubular tool electrode 200 has a contact angle of less than 90° and is hydrophilic, while the workpiece 100 has a contact angle of greater than 90° and is hydrophobic. This reduces the flow area formed by the working fluid on the surface of the workpiece 100 and improves the localization of machining.

[0063] This embodiment also simulated the flow field of the working fluid 700 jet under the constraint of the confining fluid 600 using COMSOL simulation software. The simulation area is as follows: Figure 9 As shown, this is used to analyze the flow range of working fluid 700 on the surface of workpiece 100. (As shown...) Figure 10 As shown, when the contact angle of the outer wall surface of the tubular tool electrode 200 is 90° and the contact angle of the workpiece 100 surface is also 90°, after the working fluid 700 jet is ejected from the outlet end, due to the poor wettability of the outer wall surface of the tubular electrode, a working fluid outflow channel cannot be formed on the outer wall surface in time. Even if there is a large density difference between the two liquids, the working fluid cannot flow out of the processing area in time, causing it to accumulate at the outlet end. At this time, the radius of the working fluid 700 flow area on the surface of the workpiece 100 reaches 461μm, far exceeding the outer diameter of the tubular tool electrode 200 (155μm). At this time, the constraint effect on the working fluid 700 is the worst, and the processing localization is also the worst. After surface modification treatment, the tubular tool electrode 200 has the characteristic of being affinity for the working fluid 700. When the contact angle is reduced to 10°, the contact angle of the workpiece 100 surface is still 90°. The flow field distribution at this time is as follows. Figure 11 As shown, after the working fluid 700 flows out, the increased wettability of the tool electrode's outer wall enhances its transport capacity, allowing it to be discharged promptly through the outflow channel formed by the tool electrode's outer wall. Ultimately, the radius of the working fluid 700's flow range on the workpiece 100 surface is 201 μm. When the contact angle of the tubular tool electrode 200 is 20° and the contact angle of the workpiece 100 surface is 90°, the flow field distribution is as follows: Figure 12 As shown, the radius of the flow range of the working fluid 700 on the surface of the workpiece 100 is 203 μm. When the contact angle of the tubular tool electrode 200 is 40° and the contact angle of the workpiece 100 surface is 90°, the flow field distribution is as follows. Figure 13 As shown, the radius of the flow range of the working fluid 700 on the surface of the workpiece 100 is 212 μm. Therefore, in order to make the surface 200 of the tubular tool electrode have good hydrophilicity, thereby reducing the flow range of the working fluid 700 on the surface of the workpiece 100, its contact angle range is preferably 10°-40°.

[0064] In this embodiment, the workpiece 100 also underwent surface modification treatment to increase its contact angle, thereby giving the workpiece 100 hydrophobic properties. The hydrophobicity of the workpiece can limit the lateral flow of the working fluid on the workpiece surface, further reducing the flow area of ​​the working fluid on the workpiece surface. For example... Figure 14 As shown, when the contact angle of the tubular tool electrode 200 is fixed at 20°, and the contact angle of the workpiece 100 is increased to 120°, the radius of the flow area of ​​the working fluid 700 on the surface of the workpiece 100 decreases to 174 μm; Figure 15 As shown, when the contact angle of the workpiece 100 surface increases to 135°, the radius of the flow area of ​​the working fluid 700 on the workpiece 100 surface decreases to 164 μm; Figure 16As shown, when the contact angle of the workpiece 100 surface continues to increase to 150°, the radius of the flow area of ​​the working fluid 700 on the workpiece 100 surface further decreases to 155 μm. Preferably, the contact angle range of the workpiece 100 surface is 120°-150°, which can reduce the radius of the flow area of ​​the working fluid 700 on the workpiece 100 surface. The flow field simulation results fully demonstrate that treating the outer wall of the tubular tool electrode 200 to be affinity for the working fluid 700 and treating the surface of the workpiece 100 to be de-aperture from the working fluid 700 can effectively reduce the flow range of the working fluid 700 on the workpiece 100 surface, thereby effectively improving the localization of micro-electrochemical machining.

[0065] In this embodiment, the contact angle measurement process includes measuring the contact angle of the tubular tool electrode 200 and the contact angle of the workpiece 100. When measuring the contact angle of the tubular tool electrode 200, the liquid tank 311 is placed on the worktable of the angle contact measuring instrument. A layer of working fluid 700 and constraint fluid 600 is filled into the liquid tank 311, and the tubular tool electrode 200 is vertically inserted. The angle between the boundary and the solid surface is then observed. When measuring the surface contact angle of the workpiece 100, the liquid tank 311 is placed on the worktable of the angle contact measuring instrument. A layer of constraint fluid 600 is filled into the liquid tank 311, and then a drop of working fluid 700 is added. The angle between the boundary and the solid surface is then observed.

[0066] The tubular tool electrode 200 in this embodiment is made of a metallic material with good conductivity. The electrode has a hollow structure, allowing the working fluid 700 to flow out, and its outer diameter is 50μm-300μm. In this embodiment, the outer diameter of the tubular tool electrode 200 is preferably 155μm. In step S1, the surface modification treatment of the tubular tool electrode 200 includes processing a micro / nano structure with working fluid 700 affinity on the outer wall surface and coating it with a working fluid 700 affinity coating. The tubular tool electrode 200 has a hollow structure, facilitating the flow of the working fluid 700 from the tube. To ensure that the working fluid 700 can flow upwards along the tubular tool electrode 200 and avoid forming a large flow area on the workpiece 100 surface causing stray corrosion, surface modification treatment is required for the tubular tool electrode 200. Applying a specific coating or processing a micro / nano structure can both give it working fluid 700 affinity properties, thereby improving processing accuracy.

[0067] The fabrication process of the micro / nano structure with working fluid affinity 700 in this embodiment includes immersing the outlet end in concentrated sulfuric acid, allowing it to stand, and then rinsing the tubular tool electrode 200 with clean water. For example... Figure 3 As shown, the contact angle of the untreated tubular tool electrode 200 is 88.57°, and its microstructure is as follows. Figure 5As shown, its surface structure is smooth, and its wettability with working fluid 700 is close to neutral. However, the strong acidity of concentrated sulfuric acid corrodes the electrode surface, causing it to gradually dissolve or form tiny pits and pores. During immersion, the uneven corrosion of the electrode surface by concentrated sulfuric acid leads to the formation of a micron or nanometer-level rough structure. This rough structure increases the electrode's surface area and gives it higher surface energy, thus enhancing its wettability with working fluid 700. After immersion in concentrated sulfuric acid for a period of time, it should be rinsed thoroughly with clean water to avoid excessive corrosion. Figure 4 As shown, after treatment using the above method, the contact angle becomes 19.38°, exhibiting hydrophilicity towards working fluid 700. (As...) Figure 6 As shown, after the above method is used, an approximately parallel and symmetrical micro-nano structure is formed on the surface of the tubular tool electrode 200. This structure can provide a passive wetting effect, which is conducive to the flow of liquid. Therefore, the contact angle is reduced and the wettability is improved.

[0068] During the micro / nano structure fabrication process, the immersion depth of the outlet end in concentrated sulfuric acid is 0.8cm-1.2cm, and the immersion time is 8min-12min. Since the fabrication process only requires etching the micro / nano structure at the outlet end, the immersion depth needs to be controlled. Simultaneously, the immersion time directly determines the degree of corrosion of the tubular tool electrode 200 by the concentrated sulfuric acid. It is necessary to ensure that the micro / nano structure of the working solution 700 is etched, while avoiding excessive corrosion that could damage the structure of the tubular tool electrode 200. In this embodiment, the preferred immersion depth of the outlet end in concentrated sulfuric acid is 1cm. After standing in concentrated sulfuric acid for 10min, it is rinsed thoroughly with plenty of running water.

[0069] In steps S1 and S2, both the tubular tool electrode 200 and the workpiece 100 undergo ultrasonic water bath treatment before surface modification. Ultrasonic water bath treatment can remove dirt and oil from the tubular tool electrode 200 and the workpiece 100, improving surface cleanliness and facilitating subsequent micro / nano structure processing or coating.

[0070] In step S3, the constraint fluid 600 is an insulating liquid that is immiscible with the working fluid 700, and the difference between the liquid level of the constraint fluid 600 and the surface height of the workpiece 100 is 0.5mm-1mm. In this embodiment, the working fluid 700 is typically an electrolyte, such as sodium chloride solution or sodium nitrate solution, which can be adjusted according to the solubility characteristics of the micro-electrochemical machining materials. In this embodiment, the constraint fluid 600 can be an insulating liquid with a density greater than that of the working fluid 700 and immiscible with it, such as fluorinated liquid or dichloromethane.

[0071] In step S4, the distance between the liquid outlet and the surface of workpiece 100 is 50μm-200μm. The constraint liquid 600 prevents the working liquid 700 from spreading over a large area on the surface of workpiece 100. It has a higher density than the constraint liquid 600 and is immiscible, thus improving the constraint effect of the constraint liquid 600 on the working liquid 700 and increasing machining accuracy. Simultaneously, the constraint liquid 600 needs to be an insulating liquid to avoid interfering with micro-electrolytic machining. The coverage height of the constraint liquid 600 on the surface of workpiece 100 should be adaptively adjusted according to the diameter of the tubular tool electrode 200. When the outer diameter of the tubular tool electrode 200 is small, the coverage height of the constraint liquid 600 should be appropriately reduced to ensure the stability of the flow channel formed by the working liquid 700 on the tool electrode surface.

[0072] The working principle of the micro-electrochemical machining method in this embodiment is as follows: In this embodiment, the tubular tool electrode 200 and the workpiece 100 are surface modified to obtain a tubular tool electrode 200 with an outer wall surface that is affinity for the working fluid 700 and a workpiece 100 with a surface that is repellent to the working fluid 700. Micro-electrochemical machining is performed under the condition that the working fluid 700 jet is constrained by the confining fluid 600. When the working fluid 700 flows out from the electrode, it flows out along the outer wall surface as much as possible, reducing the lateral diffusion range of the working fluid 700 on the surface of the workpiece 100, improving the localization of micro-electrochemical machining, and thus improving the machining accuracy of micro-pits, micro-grooves and other microstructures.

[0073] Example 2

[0074] This embodiment is the second embodiment of the micro-electrochemical machining method. This embodiment is similar to the first embodiment, except that in step S2, the surface modification treatment of the workpiece 100 includes coating it with a coating that repels the working fluid 700. By coating a specific coating, the surface of the workpiece 100 is made to repel the working fluid 700, thereby reducing the lateral diffusion range of the working fluid 700 on the surface of the workpiece 100 and improving the localization of the micro-electrochemical machining.

[0075] The coating process for applying a coating with the properties of working fluid 700 involves mixing fluorosilane, anhydrous ethanol, and deionized water in a beaker and stirring at room temperature to form a fluorosilane solution. The workpiece 100 is then immersed in the fluorosilane solution, allowed to stand, and then removed and dried. By immersing the workpiece 100 in the fluorosilane solution, a thin film of fluorosilane is formed on its surface. Fluorosilane is a compound containing fluorine and silicon; the fluoroalkyl group in its molecular structure gives it extremely strong hydrophobic properties. Once the fluorosilane molecular film forms, it effectively reduces the surface energy of the workpiece 100, making it difficult for the working fluid 700 to spread and wet the surface, thus achieving the effect of repelling the working fluid 700. Furthermore, the fluorosilane molecular film also exhibits good adhesion and stability, maintaining the working fluid 700 properties of the workpiece 100 for a long time. In this embodiment, the preferred mixing ratio of fluorosilane, anhydrous ethanol, and deionized water is 1:18:2. After being placed in a beaker, the mixture is stirred at room temperature for 3 hours using a magnetic stirrer. Subsequently, the workpiece 100, which has undergone ultrasonic cleaning and degreasing treatment, is immersed in the thoroughly stirred fluorosilane solution and left to stand for 24 hours. Finally, the workpiece 100 is dried using a hair dryer, thereby covering the surface of the workpiece 100 with a fluorosilane film.

[0076] In this embodiment, when the workpiece 100 is untreated, the contact angle of the surface of the workpiece 100 is measured, such as... Figure 7 As shown, the contact angle was measured to be 90.46°, and the wettability of the working fluid 700 was neutral; the measurement results after coating with a fluorosilane coating are as follows. Figure 8 As shown, the contact angle becomes 129.41°, exhibiting lipolytic properties to working fluid 700. This is because fluorosilanes can reduce the surface energy of solid surfaces, making it more difficult for the solution to spread on their surfaces.

[0077] The working principle of the micro-electrochemical machining method in this embodiment is as follows: Fluoroalkyl groups give fluorosilanes extremely strong hydrophobic properties. When a fluorosilane molecular film is formed, it can effectively reduce the surface energy of the workpiece 100, making it difficult for the working fluid 700 to spread and wet the surface of the workpiece 100, thereby achieving the effect of hydrophobic working fluid 700.

[0078] Example 3

[0079] This embodiment is the first embodiment of a micro-electrochemical machining device, including a workpiece 100, a tubular tool electrode 200, a machine tool 300, a liquid supply system, and a power supply 500. The machine tool 300 includes an X / Y axis moving platform 310 and a Z axis moving platform 320. The liquid supply system includes an injection pump 410 and a liquid storage tank 420. The liquid storage tank 420 is mounted on the Z axis moving platform 320. One end of the liquid storage tank 420 is connected to the injection pump 410, and the other end is connected to the tubular tool electrode 200. The X / Y axis moving platform 310 is provided with a liquid tank 311 for holding a constraint liquid 600 and a working liquid 700. A clamp 312 for fixing the workpiece 100 is provided in the liquid tank 311. The tubular tool electrode 200 is perpendicular to the workpiece 100. The negative terminal of the power supply 500 is connected to the tubular tool electrode 200, and the positive terminal of the power supply 500 is connected to the workpiece 100.

[0080] like Figure 2 As shown, in this embodiment of the micro-electrochemical machining apparatus, the workpiece 100 is first fixed at the bottom of the liquid tank 311 using a clamp 312. Then, a constraint liquid 600 and a working liquid 700 are added to the liquid tank 311. The injection pump 410 is turned on, and the working liquid 700 in the storage cylinder 420 is sprayed out from the tubular tool electrode 200 to form a jet of working liquid 700. The power supply 500 is turned on, so that the tubular tool electrode 200 connected to the negative electrode is used as the cathode and the tubular tool electrode 200 connected to the positive electrode is used as the anode. The relative position between the tubular tool electrode 200 and the workpiece 100 is controlled by the Z-axis moving platform 320 and the X / Y-axis moving platform 310, so as to precisely control the micro-electrochemical machining position and realize the high localization machining of micro-grooves of different shapes, with strong process flexibility.

[0081] In this embodiment, the power supply 500 can be a DC power supply 500 or a pulse power supply 500, with a set voltage between 1V and 32V. In this embodiment, the tubular tool electrode 200 is connected to the negative terminal of the power supply 500, and the workpiece 100 is connected to the positive terminal of the power supply 500 via wires. The wires must be insulated from the working fluid 700. The X / Y axis moving platform 310 and Z axis moving platform 320 used in the micro-electrochemical machining apparatus have a moving speed of 50μm / s-2000μm / s. The machining speed can be adjusted according to the required machining structure. The stroke is 200mm, adaptable to machining microstructures of various shapes.

[0082] The working principle of the micro-electrochemical machining device in this embodiment is as follows: The fixture 312 in the liquid tank 311 fixes the position of the workpiece 100. The constraint liquid 600 and the working liquid 700 are added to the liquid tank 311 in sequence. Then, the power supply 500 and the injection pump 410 are started. The relative position between the tubular tool electrode 200 and the workpiece 100 is controlled by the Z-axis moving platform 320 and the X / Y-axis moving platform 310 to perform micro-electrochemical machining.

[0083] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. 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 claims of the present invention.

Claims

1. A micro-electrochemical machining method, characterized in that, Includes the following steps: S1. Select a tubular tool electrode (200) as the cathode, and perform surface modification treatment on the tubular tool electrode (200) to make its outer wall surface have the property of being compatible with working fluid (700); S2. Provide a workpiece (100) as an anode, and perform surface modification treatment on the workpiece (100) to give its surface the properties of a working fluid (700); S3. Fix the workpiece (100) at the bottom of the liquid tank (311), add constraint liquid (600) to the liquid tank (311) until the liquid level of the constraint liquid (600) is higher than the surface of the workpiece (100), and then add working liquid (700) until the working liquid (700) covers the liquid level of the constraint liquid (600). The constraint liquid (600) has a density greater than the working liquid (700) and the constraint liquid (600) is an insulating liquid that is immiscible with the working liquid (700). S4. Connect the tubular tool electrode (200) to the reservoir (420) containing the working fluid (700), and make the outlet end of the tubular tool electrode (200) perpendicular to the surface of the workpiece (100). S5. Open the reservoir (420) to input working fluid (700) into the tubular tool electrode (200), and the working fluid (700) flows out from the outlet end; S6. Connect the tubular tool electrode (200) to the negative terminal of the power supply (500), and connect the workpiece (100) to the positive terminal of the power supply (500); S7. Turn on the power supply (500) and use a machine tool (300) to control the movement trajectory of the tubular tool electrode (200) to perform micro-electrolytic machining on the surface of the workpiece (100).

2. The micro-electrochemical machining method according to claim 1, characterized in that, After the surface modification treatment, the tubular tool electrode (200) has a contact angle range of 10° to 40°; after the surface modification treatment, the workpiece (100) has a contact angle range of 120° to 150°.

3. The micro-electrochemical machining method according to claim 2, characterized in that, In step S1, the surface modification treatment of the tubular tool electrode (200) is carried out by: processing a micro-nano structure with working fluid (700) properties on the outer wall surface, or coating a coating with working fluid (700) properties.

4. The micro-electrochemical machining method according to claim 3, characterized in that, The micro / nano structure fabrication process with working fluid affinity (700) includes immersing the outlet end in concentrated sulfuric acid, allowing it to stand, removing it, and rinsing the tubular tool electrode (200) with clean water.

5. The micro-electrochemical machining method according to claim 4, characterized in that, The immersion depth of the outlet end in concentrated sulfuric acid is 0.8cm~1.2cm, and the immersion time is 8min~12min.

6. The micro-electrochemical machining method according to claim 2, characterized in that, In step S2, the surface modification treatment of the workpiece (100) is performed by coating it with a coating having the properties of a hydrophobic working fluid (700).

7. The micro-electrochemical machining method according to claim 6, characterized in that, The method of coating with the properties of the hydrophobic working fluid (700) is to immerse the workpiece (100) in a fluorosilane solution, allow it to stand, and then take out the workpiece (100) for drying.

8. The micro-electrochemical machining method according to any one of claims 1 to 7, characterized in that, In step S3, the difference between the liquid level of the constraint liquid (600) and the surface height of the workpiece (100) is 0.5mm to 1mm.

9. The micro-electrochemical machining method according to any one of claims 1 to 7, characterized in that, In step S4, the distance between the liquid outlet end and the surface of the workpiece (100) is 50μm~200μm.

10. A micro-electrochemical machining apparatus for implementing the micro-electrochemical machining method according to any one of claims 1 to 9, characterized in that, The system includes a workpiece (100), a tubular tool electrode (200), a machine tool (300), a liquid supply system, and a power supply (500). The machine tool (300) includes an X / Y axis moving platform (310) and a Z axis moving platform (320). The liquid supply system includes an injection pump (410) and a reservoir (420). The reservoir (420) is mounted on the Z axis moving platform (320). One end of the reservoir (420) is connected to the injection pump (410), and the other end is connected to the tubular tool electrode (200). The X / Y axis moving platform (310) is provided with a liquid tank (3) for holding a constraint fluid (600) and a working fluid (700). 11) The liquid tank (311) is provided with a clamp (312) for fixing the workpiece (100), the tubular tool electrode (200) is perpendicular to the workpiece (100), the negative terminal of the power supply (500) is connected to the tubular tool electrode (200), and the positive terminal of the power supply (500) is connected to the workpiece (100); the outer wall surface of the tubular tool electrode (200) has the property of being affinity-receptive to the working fluid (700); the surface of the workpiece (100) has the property of being repellent to the working fluid (700); the density of the constraint fluid (600) is greater than the density of the working fluid (700), and the constraint fluid (600) is an insulating liquid that is immiscible with the working fluid (700).

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