Three-electrode system ultra-precision electrolytic machining device and machining method

Abstract

The application discloses a kind of three-electrode system ultra-precision electrolytic machining device and processing method, it is related to electrolytic machining technical field, electrolytic machining device includes: cathode body, workpiece, tool electrode and fixture.Cathode body is used to connect power supply negative pole;Workpiece is used to connect power supply positive pole;Tool electrode is set between cathode body and workpiece, first electrolyte passage is equipped between cathode body and the upper portion of tool electrode, and both are connected by first insulation connecting block to keep the relative position of cathode body and tool electrode, and the lower portion of tool electrode is used to be oppositely arranged with workpiece to carry out electrolytic machining;Wherein, first electrolyte passage is used to make electrolyte flow between cathode body and the upper portion of tool electrode, so that intermediate potential between cathode body potential and workpiece potential is induced on tool electrode, and fixture is used to fix workpiece and form processing area.The application can improve electrolytic machining precision and stability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical machining technology, and in particular to a three-electrode system ultra-precision electrochemical machining apparatus and machining method. Background Technology

[0002] Electrolytic machining (EMC) is a special machining method based on anodic electrochemical dissolution for material removal. During machining, the tool electrode is connected to the negative terminal of the power supply (cathode), and the metal workpiece is connected to the positive terminal (anode). A small gap of 0.2–0.6 mm is maintained between the tool electrode and the workpiece, and a high-speed flowing electrolyte passes between the electrodes. Upon energization, the anode surface loses electrons, and the anode material is dissolved and removed in the form of metal ions. The dissolution rate follows Faraday's law, exhibiting faster dissolution rates where the gap is small and slower rates where the gap is large. As the tool electrode continuously feeds, the workpiece surface gradually copies the shape of the tool electrode, achieving shape and contour replication, thus achieving the machining objective. Based on this principle, EMC offers numerous advantages, including no tool wear, burr-free machining, immunity to the mechanical properties of the workpiece, and no heat-affected layer. It is widely used in the manufacturing of key components such as aero-engine blades and disks, micro-sensors, and medical devices.

[0003] However, current dual-electrode electrolytic machining systems with the tool cathode and workpiece anode also have limitations in further improving machining accuracy and stability. Currently, the most effective way to improve electrolytic machining accuracy is to reduce the machining gap. Techniques such as pulsed current, vibration electrolysis, and high-voltage electrolytes can effectively reduce the gap. However, once the gap is reduced to 0.1 mm, it becomes difficult to further reduce it in profile electrolytic machining. This is because during electrolytic machining, a large number of insoluble products and hydrogen bubbles are generated on both the anode and cathode surfaces during anode material removal. When the gap is reduced, these products and bubbles cause blockage, making the machining process unstable. Due to the localized insulation caused by these products and bubbles, the electric field strength increases sharply under small gap conditions, making spark discharge very easy. Furthermore, the insulation prevents the workpiece material from dissolving, causing the tool electrode to collide with the workpiece during feed, resulting in a short circuit and burning the tool and workpiece surfaces, leading to machining failure.

[0004] The aforementioned problems greatly affect the accuracy and stability of electrochemical machining, thus there is an urgent need to develop new electrochemical machining technologies to further improve the accuracy and stability of electrochemical machining. Summary of the Invention

[0005] The purpose of this invention is to provide a three-electrode system ultra-precision electrolytic machining apparatus and machining method to solve the problems existing in the prior art and improve the accuracy and stability of electrolytic machining.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a three-electrode system ultra-precision electrolytic machining apparatus, comprising: a cathode body, a workpiece, a tool electrode, and a fixture. The cathode body is used to connect to the negative terminal of a power supply; the workpiece is used to connect to the positive terminal of a power supply; the tool electrode is disposed between the cathode body and the workpiece, a first electrolyte channel is provided between the upper part of the cathode body and the tool electrode, and the two are connected by a first insulating connecting block to maintain the relative position of the cathode body and the tool electrode, the lower part of the tool electrode is used to be positioned opposite the workpiece for electrolytic machining; wherein, the first electrolyte channel is used to allow electrolyte to flow between the upper part of the cathode body and the tool electrode, thereby inducing an intermediate potential on the tool electrode between the potential of the cathode body and the potential of the workpiece; The fixture is used to fix the workpiece and form a processing area.

[0007] In some embodiments, the system further includes: an elastic floating mechanism, a displacement detection unit, and a control unit. The elastic floating mechanism is used to levitably connect the tool electrode to the machine tool feed component and allow the tool electrode to generate an elastic displacement away from the feed direction when it contacts the workpiece. The displacement detection unit is used to detect the displacement of the elastic floating mechanism to determine the contact state between the tool electrode and the workpiece. The control unit is signal-connected to the displacement detection unit and the machine tool feed component and is used to control the machine tool feed component to retract when a change in displacement is detected, so as to establish a predetermined machining gap.

[0008] In some embodiments, the elastic floating mechanism includes: a guide sleeve, a guide slider, an elastic element, and a limiting block. The guide sleeve is used to connect to the machine tool feed component; the guide slider is slidably disposed within the guide sleeve and is insulated from the cathode body; the elastic element is disposed between the guide sleeve and the guide slider, and is used to apply a restoring force to the guide slider; the limiting block is disposed at the front end of the guide sleeve, and is used to limit the sliding stroke of the guide slider.

[0009] In some embodiments, the displacement detection unit is a distance sensor used to detect the relative displacement between the guide sleeve and the guide slider.

[0010] In some embodiments, the tool electrode is formed by connecting an inert electrode and a tool electrode body, with a soft conductive connector provided between the inert electrode and the tool electrode body. The soft conductive connector is squeezed and deformed during assembly to eliminate contact gaps and ensure electrical conductivity.

[0011] In some embodiments, the first insulating connecting block has a flow channel structure inside, which is used to guide the electrolyte to flow smoothly through the gap between the cathode body and the upper part of the tool electrode.

[0012] In some embodiments, the fixture is made of an insulating material and has a first electrolyte channel and a second electrolyte channel inside; the first electrolyte channel is used to guide the electrolyte to flow between the cathode body and the upper part of the tool electrode; the second electrolyte channel is used to guide the electrolyte to flow between the lower part of the tool electrode and the workpiece.

[0013] In some embodiments, the gap between the cathode body and the upper part of the tool electrode is adjustable to adjust the value of the intermediate potential.

[0014] This invention also provides a three-electrode system ultra-precision electrolytic machining method, which is performed using the three-electrode system ultra-precision electrolytic machining apparatus described above, and includes the following steps: A cathode body, a tool electrode, and a workpiece are provided, wherein the cathode body is connected to the negative terminal of a power supply, and the workpiece is connected to the positive terminal of a power supply. The electrolyte flows between the cathode body and the tool electrode, and between the tool electrode and the workpiece; When the power is turned on, the tool electrode obtains an intermediate potential between the cathode body potential and the workpiece potential under the action of the electric field and the electrolyte flow field, and the tool electrode obtains the intermediate potential. The tool electrode is driven to feed toward the workpiece for electrolytic machining.

[0015] In some embodiments, the following steps are also included: When the tool electrode comes into contact with the workpiece, the potential difference between the tool electrode and the workpiece approaches zero, and the resulting contact current is less than the burn current threshold. The contact state between the tool electrode and the workpiece is detected. When contact is detected, the tool electrode is retracted a predetermined distance to form a machining gap. Repeat the above feed, contact detection, and retraction steps to achieve stable machining of extremely small gaps.

[0016] The present invention achieves the following technical effects compared to the prior art: In this embodiment, the cathode body is connected to the negative terminal of the power supply, the workpiece is connected to the positive terminal, and the tool electrode is positioned between them and connected to the cathode body via a first insulating connecting block. When the electrolyte flows through the first electrolyte channel between the cathode body and the upper part of the tool electrode, a voltage drop is formed between the cathode body and the upper part of the tool electrode due to the resistance of the electrolyte. This induces an intermediate potential on the tool electrode between the cathode body potential and the workpiece potential. The existence of this intermediate potential makes the potential difference between the tool electrode and the workpiece significantly smaller than the total voltage of the power supply. According to Ohm's law, when the tool electrode comes into contact with the workpiece, the contact current will be much smaller than the short-circuit current in a traditional two-electrode system, thus fundamentally avoiding the risk of spark discharge and burns. Under this premise, the machining gap can be further reduced (down to the micrometer level), thereby significantly improving machining accuracy and replication accuracy. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the machining principle of a three-electrode system ultra-precision electrolytic machining device; Figure 2 This is a diagram of a three-electrode system ultra-precision electrolytic machining device; Figure 3 This is a cross-sectional view of a three-electrode system ultra-precision electrolytic machining apparatus; Figure 4 This is a schematic diagram of the assembly of the cathode body, the first insulating connecting block, and the tool electrode. Figure 5 This is a schematic diagram of the induction electrode device. Figure 6 This is a schematic diagram of the fixture structure.

[0019] In the diagram: 1-Guide sleeve; 2-Limiting block; 3-Guide slider; 4-Distance sensor; 5-Sensor fixing support; 6-Second insulating connecting block; 7-Cathode body; 8-Inlet mounting block; 9-Upper clamping body; 10-Outlet mounting block; 11-Lower clamping body; 12-Base; 13-Spring; 14-First insulating connecting block; 15-Inert electrode; 16-Copper pad; 17-Tool electrode body; 18-Workpiece; 19-Fixed base plate; 20-Induction electrode device; 21-Clamp. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide a three-electrode system ultra-precision electrolytic machining apparatus and machining method to solve the problems existing in the prior art and improve the accuracy and stability of electrolytic machining.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The following is combined Figures 1 to 6 The following describes embodiments of the present invention.

[0024] Example 1 This invention provides a three-electrode system ultra-precision electrolytic machining apparatus, comprising: a cathode body 7, a workpiece 18, a tool electrode, and a fixture 21. The cathode body 7 is used to connect to the negative terminal of a power supply; the workpiece 18 is used to connect to the positive terminal of a power supply; the tool electrode is disposed between the cathode body 7 and the workpiece 18, and a first electrolyte channel is provided between the upper part of the cathode body 7 and the tool electrode, and the two are connected by a first insulating connecting block 14 to maintain the relative position of the cathode body 7 and the tool electrode; the lower part of the tool electrode is used to be positioned opposite the workpiece 18 for electrolytic machining; wherein, the first electrolyte channel is used to allow electrolyte to flow between the upper part of the cathode body 7 and the tool electrode, thereby inducing an intermediate potential on the tool electrode between the potential of the cathode body 7 and the potential of the workpiece 18; the fixture 21 is used to fix the workpiece 18 and form a machining area.

[0025] In this embodiment, the cathode body 7 is connected to the negative terminal of the power supply, the workpiece 18 is connected to the positive terminal, and the tool electrode is disposed between the two and connected to the cathode body 7 through the first insulating connecting block 14. When the electrolyte flows through the first electrolyte channel between the cathode body 7 and the upper part of the tool electrode, a voltage drop is formed between the cathode body 7 and the upper part of the tool electrode due to the resistance of the electrolyte, thereby inducing an intermediate potential on the tool electrode between the potential of the cathode body 7 and the potential of the workpiece 18. The existence of this intermediate potential makes the potential difference between the tool electrode and the workpiece 18 significantly smaller than the total voltage of the power supply. According to Ohm's law, when the tool electrode comes into contact with the workpiece 18, the contact current will be much smaller than the short-circuit current in the traditional two-electrode system, thus fundamentally avoiding the risk of spark discharge and burns. Under this premise, the processing gap can be further reduced (down to the micrometer level, such as 4 micrometers, 10 micrometers, etc.), thereby greatly improving the processing accuracy and replication accuracy.

[0026] In some embodiments, the electrochemical machining apparatus further includes: an elastic floating mechanism, a displacement detection unit, and a control unit. The elastic floating mechanism is used to levitately connect the tool electrode to the machine tool feed component and allow the tool electrode to generate an elastic displacement away from the feed direction when it contacts the workpiece 18. The displacement detection unit is used to detect the displacement of the elastic floating mechanism to determine the contact state between the tool electrode and the workpiece 18. The control unit is signal-connected to the displacement detection unit and the machine tool feed component and is used to control the machine tool feed component to retract when a change in displacement is detected, so as to establish a predetermined machining gap.

[0027] This embodiment adds an elastic floating mechanism, a displacement detection unit, and a control unit to the first embodiment. The elastic floating mechanism enables the tool electrode to generate an elastic displacement away from the feed direction when it contacts the workpiece 18 during the feed process, avoiding rigid collision damage. The displacement detection unit monitors the displacement of the elastic floating mechanism in real time. When the displacement changes, it indicates that the tool electrode has made contact with the workpiece 18. After receiving the contact signal, the control unit immediately controls the machine tool feed component to retract a predetermined distance, thereby accurately establishing a micron-level machining gap. This closed-loop control mechanism realizes an automated process of "allowing safe contact—detection—retraction—machining," eliminating the short circuit or excessive gap problems caused by the inability to accurately detect contact in traditional methods. At the same time, since the contact itself is safe, contact detection can be repeated, significantly improving the positional accuracy and repeatability of the final machined contour, making it particularly suitable for surface machining requiring high positioning accuracy.

[0028] In some embodiments, the elastic floating mechanism includes: a guide sleeve 1, a guide slider 3, an elastic element, and a limiting block 2. The guide sleeve 1 connects to the machine tool feed component; the guide slider 3 is slidably disposed within the guide sleeve 1 and insulated from the cathode body; the elastic element is disposed between the guide sleeve 1 and the guide slider 3, and is used to apply a restoring force to the guide slider 3; the limiting block 2 is disposed at the front end of the guide sleeve 1, and is used to limit the sliding stroke of the guide slider 3. Specifically, the limiting block 2 overlaps with the movement direction of the guide slider 3, and is used to prevent the guide slider 3 from disengaging from the guide sleeve 1 under the action of the elastic element.

[0029] This embodiment specifically defines an elastic floating mechanism comprising a guide sleeve 1, a guide slider 3, an elastic element, and a limiting block 2. The guide sleeve 1 is connected to the machine tool feed component, and the guide slider 3 slides within the guide sleeve 1. The mating surface between the two provides precise linear guidance, ensuring the stability of the tool electrode feed direction. The elastic element (such as a compression spring 13) applies a restoring force, ensuring that the tool electrode remains in the extended position when not in contact, and the maximum extension is limited by the limiting block 2, thus providing a fixed zero-point reference for distance measurement. When the tool electrode contacts the workpiece 18, the elastic element is compressed, and the guide slider 3 is displaced relative to the guide sleeve 1. This displacement is linearly related to the contact force, facilitating precise quantification of the contact degree by the distance sensor 4. This purely mechanical floating structure has advantages such as high reliability, low cost, fast response, and no need for external energy, making it ideal for long-term use in humid and corrosive electrolyte environments.

[0030] A ball bearing or linear bearing can be installed between the guide sleeve 1 and the guide slider 3 to reduce friction. The elastic element can be multiple parallel springs 13 or disc springs 13 to adjust the stiffness characteristics. The limit block 2 can be an adjustable threaded structure for easy zero-point calibration. Alternatively, magnetic reset (such as permanent magnet repulsion) can be used instead of spring 13 to avoid spring fatigue. The guide sleeve 1 and guide slider 3 can be made of corrosion-resistant stainless steel or engineering plastics.

[0031] In some embodiments, the displacement detection unit is a distance sensor 4, used to detect the relative displacement between the guide sleeve 1 and the guide slider 3. Specifically, the distance sensor 4 is fixed to the guide slider 3 by a sensor fixing bracket 5. The distance sensor 4 detects the distance between itself and the limiting block 2. When this distance changes, it can be determined that the guide slider 3 has been displaced relative to the guide sleeve 1, and thus the contact state between the tool electrode and the workpiece 18 can be determined.

[0032] In this embodiment, the displacement detection unit is specifically defined as a distance sensor 4, such as a laser displacement sensor, an eddy current sensor, or a resistive linear displacement sensor. The distance sensor 4 can measure the relative displacement between the guide sleeve 1 and the guide slider 3 non-contactly or with minimal contact, offering advantages such as high precision and high response speed. Since electrolyte may splash during processing, using a sealed or waterproof distance sensor 4 ensures long-term stability. The continuous displacement signal output by the distance sensor 4 can not only determine whether contact has occurred but also reflect the magnitude of the contact force in real time (calculated through the stiffness of the elastic element), thus providing the control unit with richer information, such as detecting abnormal blockages within the processing gap (manifested as premature contact or an abnormally increased contact force). This provides a data foundation for adaptive control.

[0033] In cost-sensitive applications, simple microswitches or proximity switches can be used, outputting only a contact / non-contact switching signal. Alternatively, displacement detection can be combined with the machine tool's own encoder to indirectly determine contact by detecting changes in the feed motor current, but this method has lower accuracy.

[0034] In some embodiments, the tool electrode is formed by connecting an inert electrode 15 and a tool electrode body 17. A soft conductive connector is provided between the inert electrode 15 and the tool electrode body 17. The soft conductive connector is squeezed and deformed during assembly to eliminate contact gaps and ensure electrical conductivity.

[0035] In this embodiment, the tool electrode consists of an upper inert electrode 15 and a lower tool electrode body 17, which are connected by compression deformation during assembly via a soft conductive connector (such as a copper pad 16). This split design allows the inert electrode 15 and the tool electrode body 17 to be made of different materials: the inert electrode 15 can be made of corrosion-resistant and electrochemically stable materials (such as platinum, graphite, or titanium) to prevent it from dissolving under the influence of electrolyte and current. The tool electrode body 17 can be made of materials that are easy to precision machine and have high hardness (such as stainless steel or cemented carbide) depending on the machining surface requirements. The plastic deformation of the soft conductive connector can fill the microscopic unevenness of the contact surface between the two, achieving large-area low-resistance contact and avoiding local overheating and electrical sparks caused by point contact. At the same time, this detachable structure facilitates the replacement of the worn tool electrode body 17 while retaining the inert electrode 15, reducing the cost of use.

[0036] The flexible conductive connector can be made of gold foil, silver foil, aluminum foil, or conductive rubber. To ensure a reliable connection, multiple gaskets can be placed between the inert electrode 15 and the tool electrode body 17, or conductive adhesive can be used for bonding. Alternatively, an interference fit or thermoforming fit can be used to allow direct contact and slight plastic deformation between the two.

[0037] The cathode body 7 is a rod-shaped structure, also known as a cathode rod, made of stainless steel. Its rear end has a threaded hole for connecting the negative power supply wire during processing. The front end of the cathode body 7 forms a current path with the electrolyte and the inert electrode 15. The cathode rod is connected to the guide slider 3 via the second insulating connecting block 6, maintaining insulation while moving synchronously with the guide slider 3.

[0038] In some embodiments, the first insulating connecting block 14 has a flow channel structure inside, which is used to guide the electrolyte to flow smoothly through the gap between the cathode body 7 and the upper part of the tool electrode.

[0039] This embodiment includes a first insulating connecting block 14, made of insulating material. On one hand, it fixes the cathode body 7 and the tool electrode (or inert electrode 15) and maintains their relative positions, ensuring electrical conduction only through the electrolyte in the gap between them. On the other hand, it has an internal flow channel structure that guides the electrolyte to flow smoothly through the gap between the cathode body 7 and the upper part of the tool electrode. This stable flow field prevents eddies and bubble retention, keeping the electrolyte resistance stable and thus ensuring the stability of the intermediate potential. Furthermore, the first insulating connecting block 14 can evenly distribute the electrolyte across the entire gap cross-section, preventing product accumulation due to excessively low local flow velocities. By optimizing the flow channel shape (e.g., tapering or expanding), the pressure distribution of the electrolyte can be adjusted, further controlling bubble generation and discharge.

[0040] The first insulating connecting block 14 can be a combination of multiple blocks rather than a single piece. Its material can be polytetrafluoroethylene, ceramic, epoxy resin, or polyetheretherketone. Additionally, a temperature sensor or pressure sensor can be embedded in the first insulating connecting block 14 to monitor the processing status. Alternatively, a dedicated first insulating connecting block 14 can be omitted, and the flow channel can be formed by the shape of the cathode body 7 and the tool electrode itself.

[0041] In some embodiments, the upper surface of the first insulating connecting block 14 is provided with an upper cavity extending from top to bottom, and the lower surface is provided with an upper cavity extending from bottom to top. The cross-sectional area of ​​the upper cavity is smaller than that of the lower cavity, so that the connection between the upper cavity and the lower cavity naturally forms a limiting surface. The inert electrode 15 is installed in the lower cavity and abuts against the limiting surface above the lower cavity. The bottom of the cathode rod is provided with a protrusion with a slightly smaller cross-section, so that a stepped surface is formed on the cathode rod. The protrusion is inserted into the upper cavity, and the stepped surface abuts against the upper surface of the first insulating connecting block 14. In this state, there is a gap between the bottom of the protrusion and the top of the inert electrode 15 to facilitate the flow of electrolyte. The middle of the first insulating connecting block 14 is provided with a flow channel structure connecting the two sides and the upper cavity to guide the electrolyte to flow smoothly through the gap between the cathode rod and the inert electrode 15, ensuring the stability of the current.

[0042] In some embodiments, the outer contour surfaces of the cathode rod, the first insulating connecting block 14, and the tool electrode remain flush after assembly. This design facilitates smooth sealing and kinematic fit within the fixture 21.

[0043] In some embodiments, the clamp 21 is made of insulating material and has a first electrolyte channel and a second electrolyte channel inside; the first electrolyte channel is used to guide the electrolyte to flow between the cathode body 7 and the upper part of the tool electrode; the second electrolyte channel is used to guide the electrolyte to flow between the lower part of the tool electrode and the workpiece 18.

[0044] The fixture 21 in this embodiment is made of insulating material and has a first electrolyte channel and a second electrolyte channel inside, serving the upstream gap (between the cathode body 7 and the upper part of the tool electrode) and the downstream gap (between the lower part of the tool electrode and the workpiece 18), respectively. The two channels are independent of each other, allowing for separate control of the electrolyte composition, flow rate, pressure, and even temperature. For example, a high-conductivity electrolyte can be used in the upstream gap to reduce ohmic losses, while a low-conductivity electrolyte can be used in the downstream gap to achieve higher machining accuracy. The independent channels also prevent air bubbles or products generated upstream from entering the downstream machining area, avoiding interference with machining stability.

[0045] The clamp 21 specifically includes an upper clamping body 9, a lower clamping body 11, a base 12, a fixed base plate 19, an inlet mounting block 8, and an outlet mounting block 10. The upper clamping body 9 is made of insulating material, and its interior upper part houses a cavity structure and a sensing electrode device 20 (e.g., Figure 5 As shown, the elastic floating mechanism, cathode body 7, tool electrode, and first insulating connecting block 14 (collectively referred to as induction electrode device 20) work together to ensure that the induction electrode device 20 can move linearly within the cavity and has good sealing performance. The upper clamping body 9 is also provided with a flow channel structure. The size of this flow channel structure must ensure that when the induction electrode device 20 moves within the cavity for processing, the inlet and outlet of the flow channel on the first insulating connecting block 14 are always kept within the flow channel, thereby ensuring that electrolyte can always flow at high speed between the cathode rod and the inert electrode 15 during the processing.

[0046] In some embodiments, the lower clamping body 11 is made of insulating material and is connected to the upper clamping body 9. The contact surfaces are precisely fitted to ensure a seal, and together with the upper clamping body 9, they close to form an electrolyte channel for providing high-voltage, high-speed electrolyte to the machining gap. The base 12 is made of stainless steel and is installed on the lower part of the lower clamping body 11 and precisely fitted. A positioning structure (e.g., a positioning pin) is provided between the two. The base 12 has a positioning surface and a clamping structure (e.g., a wedge block or a clamping screw) machined inside. The workpiece 18 is installed on the lower clamping body 11 and precisely fitted with the positioning surface of the base 12 to ensure positional accuracy. After installation, the machining surface of the workpiece 18 is directly opposite the machining profile below the tool electrode.

[0047] In some embodiments, the fixing base plate 19 is made of stainless steel, installed below the base 12 and in contact with the workpiece 18 to ensure current conduction between them. The fixing base plate 19 is machined with connection holes for connecting the positive power supply wire.

[0048] In some embodiments, the inlet mounting block 8 is tightly fitted with the upper clamping body 9 and the lower clamping body 11, and is positioned on one side of the inlet. An inlet pipe can be connected to it to supply electrolyte to the gap between the cathode rod and the inert electrode 15 and the gap between the tool electrode and the workpiece 18, respectively. The outlet mounting block 10 is tightly fitted with the upper clamping body 9 and the lower clamping body 11, and is positioned on one side of the outlet. An outlet pipe can be connected to it to discharge the electrolyte and processed products from the two gaps, respectively.

[0049] In some embodiments, the gap between the cathode body 7 and the upper part of the tool electrode can be adjusted to regulate the value of the intermediate potential.

[0050] In this embodiment, the gap between the cathode body 7 and the upper part of the tool electrode is adjustable. According to the voltage divider formula, the width of this gap directly determines the resistance value of the electrolyte in that section, thereby affecting the intermediate potential induced on the tool electrode.

[0051] It is understood that this embodiment has two specific implementation schemes: 1. During the manufacturing stage of the three-electrode system ultra-precision electrolytic machining device, the value of the intermediate potential can be adjusted by adjusting the gap between the two electrodes. After the manufacturing is completed, the gap cannot be adjusted, meaning that a three-electrode system ultra-precision electrolytic machining device can only be adapted to the processing of one type of product.

[0052] After the two- or three-electrode system ultra-precision electrolytic machining apparatus is manufactured, the gap size can be changed mechanically (e.g., by using threads, shims, or wedges). This allows for continuous adjustment of the potential difference between the tool electrode and the workpiece 18 without replacing any parts, thereby controlling the maximum contact current and machining current density. This adjustment function enables the same apparatus to adapt to machining tasks with different materials and precision requirements. For example, for high-alloy materials that are prone to sparking, the gap can be increased to obtain a lower potential difference; for materials requiring high-efficiency machining, the gap can be decreased to obtain a higher current density. The adjustment process is simple and intuitive, requiring no adjustment of electrical parameters.

[0053] Example 2 This invention also provides a three-electrode system ultra-precision electrolytic machining method, which is performed using the three-electrode system ultra-precision electrolytic machining apparatus described above, and includes the following steps: A cathode body 7, a tool electrode, and a workpiece 18 are provided. The cathode body 7 is connected to the negative terminal of the power supply, and the workpiece 18 is connected to the positive terminal of the power supply. The electrolyte flows between the cathode body 7 and the tool electrode, and between the tool electrode and the workpiece 18; When the power is turned on, the tool electrode obtains an intermediate potential between the potential of the cathode body 7 and the potential of the workpiece 18 under the action of the electric field and the electrolyte flow field. The drive tool electrode is fed toward the workpiece 18 for electrolytic machining.

[0054] This embodiment provides a method for electrolytic machining using the aforementioned apparatus. First, the cathode body 7 is connected to the negative terminal of the power supply, and the workpiece 18 is connected to the positive terminal. Then, the electrolyte flows simultaneously between the cathode body 7 and the tool electrode, and between the tool electrode and the workpiece 18. After the power is turned on, due to the upstream gap, an intermediate potential between the potential of the cathode body 7 and the potential of the workpiece 18 is induced on the tool electrode. At this time, the tool electrode is driven to feed towards the workpiece 18, and anodic dissolution occurs on the surface of the workpiece 18 under a low potential difference. This method achieves stable machining without the need for complex short-circuit detection and protection circuits. Because the potential difference between the tool electrode and the workpiece 18 is much lower than the total voltage of the power supply, even if there is occasional contact during the feeding process, no destructive arc or short circuit will occur, greatly improving the reliability and safety of the machining process.

[0055] In some embodiments, the following steps are also included: When the tool electrode comes into contact with the workpiece 18, the potential difference between the tool electrode and the workpiece 18 approaches zero, and the resulting contact current is less than the burn current threshold. The contact state between the detection tool electrode and the workpiece 18 is detected. When contact is detected, the tool electrode is retracted a predetermined distance to form a machining gap. Repeat the above feed, contact detection, and retraction steps to achieve stable machining of extremely small gaps.

[0056] In this embodiment, when the tool electrode comes into contact with the workpiece 18, the potential difference between them is extremely small, and the contact current is less than the burn threshold, so the workpiece 18 or the tool will not be damaged. At this time, the contact signal is detected by the displacement detection unit (such as distance sensor 4), and the control unit immediately instructs the machine tool feed component to retract a predetermined distance, thereby accurately establishing the required micron-level machining gap. By repeating the above feed, contact detection, and retraction cycle, a very small and uniform machining gap can be maintained throughout the entire machining process. This "step-contact-retraction-machining" working mode integrates the contact sensing principle of electrical discharge machining, but without the thermal damage of electrical discharge machining, while utilizing the high surface quality advantage of electrolytic machining. Finally, the machining endpoint of the workpiece 18 contour can be accurately determined by the last contact position, significantly improving the contour repeatability accuracy.

[0057] The retraction distance can be dynamically adjusted according to process requirements. For example, a larger retraction distance can be used in the early stages of machining to ensure chip removal, while a very small retraction distance can be used in the later stages to refine the contour. Contact detection can also use current or force signals as auxiliary judgments. The retraction speed can be controlled in segments. In addition, the machine can be briefly held still after each retraction to allow the electrolyte to flush the gap. This method is also applicable to simple machine tools without an automatic control unit, in which case the operator can manually control the retraction by observing the sensor signals.

[0058] Example 2 Based on Example 2, this example provides a more specific method for ultra-precision electrolytic machining of a three-electrode system, including the following steps: Step 1: The cathode body 7 is connected to the negative terminal of the power supply via a conductive wire, and the fixed base plate 19 is connected to the positive terminal of the power supply. The two inlet (outlet) ports on the inlet mounting block 8 and the outlet mounting block 10 are respectively connected to the electrolyte circulation system through separate pipelines and are circulated with high-speed flowing electrolyte.

[0059] Step 2: After the power is turned on, the potential of the cathode body 7 is U0, the potential of the workpiece 18 is U2, and the inert electrode 15, the copper pad 16, and the tool electrode body 17, as a whole, induce positive charges on the upper surface of the inert electrode 15 and negative charges on the lower surface of the tool electrode body 17 in the electric field environment. The overall potential is U1, which is between the potential of the cathode body 7 U0 and the potential of the workpiece 18 U2. <U1≤U2。

[0060] Step 3: The sensing electrode device 20 moves linearly under the drive of the machine tool spindle or motion platform. Its guide sleeve 1 is directly connected to the machine tool feed component, and moves synchronously with the guide slider 3, distance sensor 4, sensor fixing support 5, second insulating connecting block 6, cathode body 7, first insulating connecting block 14, inert electrode 15, copper pad 16, and tool electrode body 17. When the tool electrode body 17 is not in contact with the workpiece 18, the guide slider 3 is always pushed against the limiting block 2 under the pushing force of the spring 13 (this pushing force is greater than the resultant force of the electrolyte pressure and friction). The guide slider 3, distance sensor 4, sensor fixing support 5, second insulating connecting block 6, cathode body 7, first insulating connecting block 14, inert electrode 15, copper pad 16, and tool electrode body 17 always maintain communication with the guide sleeve 1. When the tool electrode body 17 comes into contact with the workpiece 18, the workpiece 18, fixed to the fixture 21 and the machine tool, exerts a reverse thrust on the tool electrode body 17. This thrust is greater than the thrust of the spring 13, causing the spring 13 to compress and deform. This results in the guide sleeve 1 remaining stationary with respect to the cathode body 7, tool electrode body 17, distance sensor 4, and other connected components, while the guide slider 3 remains stationary during the feed motion of the machine tool. The displacement between the guide sleeve 1 and the guide slider 3 can be measured by the distance sensor 4.

[0061] Step 4: As the induction electrode device 20 feeds, when the tool electrode body 17 and the workpiece 18 are not in contact, a potential difference ΔU = U2 ≤ U1 is maintained between them. Due to this potential difference, an oxidation reaction occurs on the surface of the workpiece 18, causing the workpiece material to lose electrons and dissolve into the electrolyte in the form of ions. The electrolyte products and heat generated are carried away and removed by the scouring action of the electrolyte. As the feeding motion continues, the potential U1 of the tool electrode body 17 continuously increases and gets closer and closer to the potential U2 of the workpiece 18. When the tool electrode body 17 and the workpiece 18 come into contact, U1 becomes the same as U2, and the potential difference ΔU between them smoothly becomes 0. Therefore, the tool electrode body 17 and the workpiece 18 do not experience short-circuit burns after contact as in traditional machining, but instead maintain a stable current value I0 after contact. By controlling the gap between the cathode body 7 and the inert electrode 15, the maximum contact current I between the tool electrode body 17 and the workpiece 18 can be adjusted. max , ensure I max The current is less than the burn current threshold of the tool electrode body 17 and the workpiece 18. This enables safe, burn-free machining throughout the entire process, greatly improving machining stability.

[0062] Step 5: Detect the feedback value from distance sensor 4. When the value is a constant initial value, it means that the tool electrode body 17 and the workpiece 18 are not in contact. When the value of distance sensor 4 changes, the tool electrode body 17 and the workpiece 18 are in contact. At this time, the machine tool motion mechanism can be moved back to the point where the signal from distance sensor 4 is a constant initial value. This position is then determined to be the contact critical value. The mechanism can then be moved back a certain distance, which can be considered the machining clearance.

[0063] Additionally, depending on actual processing needs, a larger initial retraction distance can be achieved, rapidly increasing the gap between the tool electrode body 17 and the workpiece 18. When the gap exceeds a certain threshold, the processing current is cut off, pausing the dissolution of the workpiece 18. Increasing the gap enhances the electrolyte's flushing ability, quickly removing products, heat, and bubbles from the gap. After achieving a clean gap, the feed motion resumes. When the gap falls below a certain threshold, energization is resumed, again achieving anodic dissolution of the workpiece 18 and removing the material. By controlling the retraction distance and the gap threshold for energization and de-energization, precision machining of extremely small gaps can be achieved.

[0064] Step 6: Repeating steps 4 and 5 allows for the periodic updating and adjustment of the machining area state. Since short-circuit arcing does not occur, contact between the tool and workpiece 18 is permitted, enabling machining with extremely small gaps (down to the micrometer level). Furthermore, because contact is allowed, the final position of the workpiece 18's contour can be accurately measured during machining, resulting in a more precise tool-stopping position and improved workpiece 18 contour positioning accuracy and repeatability.

[0065] Step 7: When the workpiece 18 contour is detected to be in the final contour position, stop machining, retract the machine tool spindle and motion platform, and turn off the electrolyte circulation system and power system to complete the machining and obtain the final workpiece 18 contour.

[0066] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A three-electrode system ultra-precision electrolytic machining apparatus, characterized in that, include: The cathode body is used to connect to the negative terminal of the power supply; The workpiece is used to connect to the positive terminal of the power supply. A tool electrode is disposed between the cathode body and the workpiece. A first electrolyte channel is provided between the upper part of the cathode body and the tool electrode, and the two are connected by a first insulating connecting block to maintain the relative position of the cathode body and the tool electrode. The lower part of the tool electrode is used to be positioned opposite to the workpiece for electrolytic machining. The first electrolyte channel is used to allow the electrolyte to flow between the cathode body and the upper part of the tool electrode, thereby inducing an intermediate potential on the tool electrode between the cathode body potential and the workpiece potential. A fixture is used to fix the workpiece and form a processing area.

2. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 1, characterized in that: Also includes: An elastic floating mechanism is used to levitably connect the tool electrode to the machine tool feed component and allow the tool electrode to generate an elastic displacement away from the feed direction when it contacts the workpiece. The displacement detection unit is used to detect the displacement of the elastic floating mechanism in order to determine the contact state between the tool electrode and the workpiece. The control unit is connected to the displacement detection unit and the machine tool feed component via signals. It is used to control the machine tool feed component to retract when a change in displacement is detected, so as to establish a predetermined machining gap.

3. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 2, characterized in that, The elastic floating mechanism includes: Guide sleeve, used to connect the machine tool feed components; A guide slider is slidably disposed within the guide sleeve and is insulated from the cathode body; An elastic element is disposed between the guide sleeve and the guide slider, for applying a restoring force to the guide slider; A limiting block is disposed at the front end of the guide sleeve rod to limit the sliding stroke of the guide slider.

4. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 3, characterized in that, The displacement detection unit is a distance sensor used to detect the relative displacement between the guide sleeve and the guide slider.

5. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 1, characterized in that, The tool electrode is composed of an inert electrode and a tool electrode body connected together. A soft conductive connector is provided between the inert electrode and the tool electrode body. The soft conductive connector is squeezed and deformed during assembly to eliminate contact gaps and ensure electrical conductivity.

6. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 1, characterized in that, The first insulating connecting block has a flow channel structure inside, which is used to guide the electrolyte to flow smoothly through the gap between the cathode body and the upper part of the tool electrode.

7. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 1, characterized in that, The clamp is made of insulating material and has a first electrolyte channel and a second electrolyte channel inside; the first electrolyte channel is used to guide the electrolyte to flow between the cathode body and the upper part of the tool electrode; The second electrolyte channel is used to guide the electrolyte flow between the lower part of the tool electrode and the workpiece.

8. The three-electrode system ultra-precision electrolytic machining apparatus according to claim 1, characterized in that, The gap between the cathode body and the upper part of the tool electrode is adjustable to adjust the value of the intermediate potential.

9. A method for ultra-precision electrolytic machining using a three-electrode system, characterized in that, The process, performed using the three-electrode system ultra-precision electrolytic machining apparatus according to any one of claims 1 to 8, includes the following steps: A cathode body, a tool electrode, and a workpiece are provided, wherein the cathode body is connected to the negative terminal of a power supply, and the workpiece is connected to the positive terminal of a power supply. The electrolyte flows between the cathode body and the tool electrode, and between the tool electrode and the workpiece; When the power is turned on, the tool electrode obtains an intermediate potential between the cathode body potential and the workpiece potential under the action of the electric field and the electrolyte flow field, and the tool electrode obtains the intermediate potential. The tool electrode is driven to feed toward the workpiece for electrolytic machining.

10. The ultra-precision electrolytic machining method with a three-electrode system according to claim 9, characterized in that, It also includes the following steps: When the tool electrode comes into contact with the workpiece, the potential difference between the tool electrode and the workpiece approaches zero, and the resulting contact current is less than the burn current threshold. The contact state between the tool electrode and the workpiece is detected. When contact is detected, the tool electrode is retracted a predetermined distance to form a machining gap. Repeat the above feed, contact detection, and retraction steps to achieve stable machining of extremely small gaps.

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