Electrochemical machining device and electrostatic driving micro-feeding actuator based on magnetic suspension support

Abstract

The application provides an electrochemical machining device based on a magnetic suspension support and an electrostatic driving micro-feeding actuator, and the electrostatic driving micro-feeding actuator comprises a shell, an electrostatic driving stator electrode plate, an electrostatic driving rotor, a stator coil, an inner shaft and a tool electrode; the electrostatic driving stator electrode plate, the electrostatic driving rotor, the stator coil and the inner shaft are coaxially arranged in the shell; the electrostatic driving stator electrode plate is fixedly arranged at the top of the shell, the stator coil is fixedly arranged in the shell, the electrostatic driving rotor is suspended between the electrostatic driving stator electrode plate and the stator coil, the top of the inner shaft is fixedly connected with the electrostatic driving rotor after penetrating through the stator coil, and the bottom of the inner shaft is connected with the tool electrode after penetrating out of the shell. The application improves the electrochemical machining speed and stability, reduces the stray effect and improves the electrochemical machining precision.

Description

Technical Field

[0001] This invention relates to the field of electrolytic machining technology, and in particular to an electrostatically driven micro-feed actuator and electrolytic machining apparatus based on magnetic levitation support. Background Technology

[0002] Electrolytic machining (EMC) is a machining process based on the principle that the metal anode gains electrons during electrolysis, oxidizing into metal ions that dissolve in the electrolyte. The workpiece acts as the electrolytic anode, and the cutting tool as the electrolytic cathode, thus removing material from the workpiece. Because EMC is a non-contact process, there is no cutting stress between the workpiece and the cutting tool. Furthermore, due to the reduction reaction at the cathode during electrolysis, the cutting tool electrode experiences minimal wear. Therefore, EMC is an excellent choice for continuous precision machining, showing promising application prospects for processing micro-parts, micro-holes, and micro-three-dimensional structures. However, maintaining a very small, micrometer-scale distance between the workpiece and the cutting tool during EMC directly affects the success and accuracy requirements. Traditional EMC methods rely on high-precision and expensive machine tools, which significantly limits its practical applications. In the current context of domestic manufacturing, the precision of common servo motors or linear motors is around tens of micrometers, which cannot meet the precision requirements of micro-electrolysis. Although linear motors equipped with high-precision grating rulers can achieve a precision of 0.01μm, they are expensive and their control software is not open source, making them difficult to apply in small and medium-sized processing enterprises. Therefore, a low-cost and simple-to-control processing method is needed to achieve micrometer-level control of electrode spacing. In the aerospace field, the machining of guide holes for turbine blades in aero-engines has always been one of the problems hindering the independent development of domestic engines. Electrolytic machining, because it avoids the contact stress of mechanical machining and the melting effect of electrical discharge machining, achieves its processing purpose through particle removal, resulting in a smooth and crack-free surface, making it a suitable method for precision micro-electrolytic hole machining. To solve the problem of difficulty in controlling the inter-electrode gap in electrolytic machining, scholars at home and abroad have conducted extensive research and attempts. Researchers Zhao Chenglu and Li Xing from Harbin Institute of Technology (Shenzhen) employed a planar electrode method for electrolytic machining. Using a thin planar electrode sheet as the tool electrode, micro-feeding was achieved by electrostatic force between the tool electrode and the workpiece, causing the electrode sheet to deform. During machining, charge transfer resulted in springback, allowing the tool electrode to move away from the workpiece, completing one machining cycle. While this deformation-driven electrostatic micro-feeding method enables adaptive machining with small gaps, its large area leads to low current density and slow machining speed. Furthermore, the relatively simple shape of the tool electrode cannot adapt to machining complex structures. Similar to electrostatically driven micro-feeding, domestic and international scholars have conducted research on ultrasonic-assisted micro-electrolytic machining, achieving promising results. Polish scholar A Rusza applied ultrasonic vibrations with a frequency of 22 kHz and an amplitude of less than 16 μm to the tool electrode and compared them with conventional electrolytic machining. Similarly, Skoczypiec performed assisted electrolytic machining with a frequency of 20 kHz and a tool amplitude of less than 10 μm, which effectively improved the MRR. Korean scholar Insoon Yang performed deep hole machining on 304 stainless steel with an ultrasonic frequency of 40 kHz and an amplitude of 4 μm.The comparison shows that ultrasonic-assisted electrochemical machining can effectively improve the electrochemical machining effect, including the improvement of workpiece surface quality, microhole depth and precision, and the higher the auxiliary ultrasonic frequency and the smaller the amplitude, the better the machining effect.

[0003] Huang Ruining from Harbin Institute of Technology (Shenzhen) proposed a novel electrostatically driven assisted electrolytic machining method. This method utilizes electrostatic force to drive the deformation of the tool electrode. When the deformation reaches a certain degree and the machining gap between the two electrode plates is reached, corresponding electrolytic machining occurs between the two plates. Figure 1 As shown. During the processing, charge migration occurs during electrolysis, reducing the charge on the electrode plates and gradually decreasing the electrostatic force. When the electrostatic force is less than the elastic force of the electrode plates, the plates will return to their original shape under the action of the elastic force. Although this method can achieve small-stroke micro-feed, it also has many problems. Because the electrode sheet is used as the tool electrode, the large area of ​​the electrode sheet results in low current density, leading to a slow processing speed. The parallel plate electrostatic drive method is prone to short circuits due to the attraction effect, and the electrode plates are short and difficult to control. The application range is limited; for more complex three-dimensional structures, the processing method using planar electrodes is inadequate. Summary of the Invention

[0004] The main objective of this invention is to provide an electrostatically driven micro-feed actuator and an electrolytic machining device based on magnetic levitation support, which aims to improve the speed and stability of electrolytic machining, reduce stray effects, and enhance the accuracy of electrolytic machining.

[0005] To achieve the above objectives, this invention proposes an electrostatically driven micro-feed actuator based on magnetic levitation support, comprising: a housing, an electrostatically driven stator electrode plate, an electrostatically driven mover, a stator coil, an inner shaft, and a tool electrode;

[0006] The electrostatic drive stator electrode plate, electrostatic drive mover, stator coil, and inner shaft are coaxially arranged inside the housing;

[0007] The electrostatic drive stator electrode plate is fixedly disposed on the top of the housing, the stator coil is fixedly disposed inside the housing, the electrostatic drive mover is suspended between the electrostatic drive stator electrode plate and the stator coil, the top of the inner shaft passes through the stator coil and is fixedly connected to the electrostatic drive mover, and the bottom of the inner shaft passes through the housing and is connected to the tool electrode.

[0008] A further technical solution of the present invention is that the electrostatic drive actuator includes an electrostatic drive actuator electrode plate, an induction coil and a permanent magnet arranged sequentially from top to bottom, and the inner shaft passes through the permanent magnet and the induction coil and is fixedly connected to the electrostatic drive actuator electrode plate.

[0009] A further technical solution of the present invention is that a linear limiting bearing is provided at the bottom of the outer shell, and the inner shaft passes through the linear limiting bearing.

[0010] A further technical solution of the present invention is that the stator coil is a stator coil with an internal iron-nickel alloy.

[0011] A further technical solution of the present invention is that the induction coil is a copper induction coil.

[0012] A further technical solution of the present invention is that the inner shaft is a smooth hollow structure.

[0013] A further technical solution of the present invention is that the outer casing is also provided with an electrical connection hole.

[0014] A further technical solution of the present invention is that a mounting post is provided on the top of the outer shell.

[0015] To achieve the above objectives, the present invention also proposes an electrolytic machining apparatus, which includes an electrostatically driven micro-feed actuator based on magnetic levitation support as described above.

[0016] Compared with other high-frequency ultrasonic oscillators, the electrostatically driven micro-feed actuator and electrolytic machining device based on magnetic levitation support of this invention have advantages such as less thermal effect and fast amplitude modulation response. When applied to the field of assisted electrolytic machining, it can effectively eliminate problems such as bubble adhesion, impurity accumulation and poor electrolyte circulation during electrolysis. It has a significant improvement effect on the machining of complex three-dimensional structures such as deep small holes, and can significantly improve the machining speed and stability, reduce stray effects, and significantly improve the accuracy of electrolytic machining. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of electrode-plate electrostatic driven assisted electrolytic machining;

[0018] Figure 2 This is a schematic diagram of the main internal drive components of the electrostatically driven micro-feed actuator based on magnetic levitation support according to the present invention.

[0019] Figure 3 yes Figure 2 A cross-sectional view along the AA direction;

[0020] Figure 4 This is a schematic diagram of the overall structure of the electrostatically driven micro-feed actuator based on magnetic levitation support of the present invention;

[0021] Figure 5 yes Figure 4 A cross-sectional view along the AA direction;

[0022] Figure 6 This is a schematic diagram of the electrolytic processing apparatus of the present invention;

[0023] Figure 7 This is a schematic diagram of the power connection of an electrostatically driven micro-feed actuator based on magnetic levitation support.

[0024] Explanation of icon numbers:

[0025] 1. Housing; 2. Electrostatic drive stator electrode plate; 3. Electrostatic drive mover; 4. Stator coil; 5. Inner shaft; 6. Tool electrode; 7. Stator coil base; 8. Electrostatic drive mover electrode plate; 9. Induction coil; 10. Permanent magnet; 11. Linear limit bearing; 12. Power connection hole; 13. Mounting pin; 14. Machine tool; 15. Electrostatic drive power supply and controller; 16. Electrolytic pulse power supply; 17. Workpiece; 18. Electrolyte circulation system; 19. Electrolyte; 20. Electrolytic cell; 21. Resistor.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] To address the problems of existing technologies, such as the inability of CNC machine tools to meet the requirements of electrolytic machining in terms of feed accuracy, the low current density and slow machining speed of traditional electrostatic drive-assisted electrolytic machining, the easy damage of tool electrodes due to electrostatic absorption effects leading to malfunction, and the limited variety of tool electrode shapes that can be used in traditional electrode-type electrostatic drives, this invention proposes a solution.

[0029] This invention proposes an electrostatically driven micro-feed actuator based on magnetic levitation support. The technical solution adopted by the electrostatically driven micro-feed actuator based on magnetic levitation support mainly relies on electromagnetic levitation force to suspend the movable electrode plate (electrostatically driven mover electrode plate) near the electrostatically driven stator electrode plate, and uses the electric field force between the electrostatically driven mover electrode plate and the electrostatically driven stator electrode plate as the excitation source, so that the mover drives the processing electrode to achieve precise movement.

[0030] Specifically, please refer to Figures 2 to 5 The present invention relates to an electrostatically driven micro-feed actuator based on magnetic levitation support, characterized in that it comprises: a housing 1, an electrostatically driven stator electrode plate 2, an electrostatically driven mover 3, a stator coil 4, an inner shaft 5, and a tool electrode 6.

[0031] The electrostatic drive stator electrode plate 2, the electrostatic drive mover 3, the stator coil 4, and the inner shaft 5 are coaxially arranged inside the outer casing 1.

[0032] The electrostatic drive stator electrode plate 2 is fixedly installed on the top of the housing 1. The stator coil 4 is fixedly installed inside the housing 1 through the stator coil base 7. The electrostatic drive mover 3 is suspended between the electrostatic drive stator electrode plate 2 and the stator coil 4. The top of the inner shaft 5 passes through the stator coil 4 and is fixedly connected to the electrostatic drive mover 3. The bottom of the inner shaft 5 passes through the housing 1 and is connected to the tool electrode 6.

[0033] Furthermore, in this embodiment, the electrostatic drive actuator 3 includes an electrostatic drive actuator electrode plate 8, an induction coil 9, and a permanent magnet 10 arranged sequentially from top to bottom. The inner shaft 5 passes through the permanent magnet 10 and the induction coil 9 and is fixedly connected to the electrostatic drive actuator electrode plate 8.

[0034] Furthermore, in this embodiment, a linear limiting bearing 11 is provided at the bottom of the outer casing 1, and the inner shaft 5 passes through the linear limiting bearing 11. By passing the inner shaft 5 through the linear limiting bearing 11, this embodiment can further improve the motion stability and precision of the inner shaft 5.

[0035] Furthermore, in this embodiment, the stator coil 4 is a stator coil 4 with an internal iron-nickel alloy.

[0036] Furthermore, in this embodiment, the induction coil 9 is a copper induction coil 9.

[0037] Furthermore, in this embodiment, the inner shaft 5 is a smooth, hollow structure. This embodiment uses a smooth, hollow inner shaft 5 to facilitate the guidance, installation, and power supply of the tool electrode 6.

[0038] Furthermore, in this embodiment, the outer casing 1 is also provided with an electrical connection hole 12.

[0039] Furthermore, in this embodiment, a mounting post 13 is provided on the top of the outer casing 1. The mounting post is used to mount the entire electrostatically driven micro-feed actuator based on magnetic levitation support onto the machine tool.

[0040] The structure and working principle of the electrostatically driven micro-feed actuator based on magnetic levitation support of the present invention will be further described in detail below.

[0041] Figure 2 This is a schematic diagram of the main internal drive components of the electrostatically driven micro-feed actuator based on magnetic levitation support according to the present invention. Figure 3 yes Figure 2 Sectional view along the AA direction. Figure 4 This is a schematic diagram of the overall structure of the electrostatically driven micro-feed actuator based on magnetic levitation support according to the present invention. Figure 5 yes Figure 4 A cross-sectional view along the AA direction.

[0042] The electrostatically driven micro-feed actuator based on magnetic levitation has a stator coil 4 at its bottom, made of iron-nickel alloy (high permeability alloy), which generates electromagnetic levitation force. The rising distance of the electrostatically driven mover electrode plate 8 can be controlled by the input current to accommodate tool electrodes 6 of different specifications. The electrostatically driven mover 3 has a three-layer structure, consisting of a permanent magnet 10, an induction coil 9, and the electrostatically driven mover electrode plate 8 from bottom to top, and is guided by an inner shaft 5. The permanent magnet 10 and the bottom stator coil 4 generate magnetic repulsion, thus achieving levitation. Furthermore, the attraction between the iron electrostatically driven mover electrode plate 8 and the permanent magnet fixes the copper induction coil 9 in the middle position. Due to mutual inductance, the induction coil 9 generates an induced current when current is applied to the stator coil 4, and this induced current changes with the mover's movement, used to monitor the mover's position. The inner shaft 5 is a smooth, hollow shaft, facilitating guidance, tool electrode 6 installation, and power supply. The electrostatically driven mover electrode plate 8 moves to the vicinity of the electrostatically driven stator electrode plate under the action of magnetic levitation force, and controls the distance between the electrode plates to be on the order of micrometers to reach a state of equilibrium. Then, the electrostatic driving voltage is turned on, and the electrostatically driven mover electrode plate 8 will move due to the action of electric field force, thereby achieving the purpose of micro-feeding.

[0043] Compared with other high-frequency ultrasonic oscillators, the electrostatically driven micro-feed actuator based on magnetic levitation support has advantages such as less thermal effect and fast amplitude modulation response. When applied to the field of assisted electrolytic machining, it can effectively eliminate problems such as bubble adhesion, impurity accumulation and poor electrolyte circulation during electrolysis. It has a significant improvement effect on the machining of complex three-dimensional structures such as deep small holes, and can significantly improve the machining speed and stability, reduce stray effects, and significantly improve the accuracy of electrolytic machining.

[0044] To achieve the above objectives, the present invention also proposes an electrolytic machining apparatus, which includes the electrostatically driven micro-feed actuator based on magnetic levitation support as described above.

[0045] Specifically, please refer to Figure 6The electrolytic machining apparatus of this invention mainly consists of a CNC motion platform, an electrostatic drive power supply and controller 15, an electrostatic drive micro-feed actuator based on magnetic levitation support, an electrolytic pulse power supply 16, an electrolytic tool electrode 6, a workpiece 17, and an electrolyte circulation system 18. The electrostatic drive power supply and controller 15 provides power to the micro-feed actuator and is controlled by the machining power supply, ensuring synchronization between machining and electrostatic drive. The CNC motion platform is an XYZ three-axis machine tool 14, controlled by a host computer, and stable control can be achieved through G-code operations via the host computer. The electrolytic pulse power supply 16 can be a transistor-controlled pulse power supply or an RC (resistor 21 capacitor) pulse power supply, with a low open-circuit voltage, supplying power to the tool electrode 6 and workpiece 17 during electrolysis. The tool electrode 6 is a copper rod or other electrodes required for machining; the workpiece 17 can be any metal part to be machined; the electrolyte 19 is a conventional electrolytic machining solution, such as a neutral or weakly acidic electrolyte solution, and suitable complexing agents can be added to improve machining accuracy. The electrolyte circulation system 18 is a pump-type liquid supply device. Since the electrolyte concentration decreases during the electrolysis process, the electrolysis process slows down. The electrolyte circulation system 18 can provide fresh electrolyte 19 to the electrolytic cell 20 to maintain the relative stability of the electrolyte 19 concentration.

[0046] A schematic diagram of the power connection of the electrolytic processing apparatus of the present invention is shown below. Figure 7 As shown. The electrostatically driven micro-feed actuator based on magnetic levitation support is divided into three layers: upper, middle, and lower. The upper layer is a fixed unit (electrostatically driven stator electrode plate 2), which can be directly fixedly connected to the driver housing 1; the middle layer, the mover (electrostatically driven mover 3), is a movable unit, which includes the uppermost electrostatically driven mover electrode plate 8, the middle vortex induction coil 9, and the lowermost permanent magnet 10, which is connected to the inner shaft 5 and the tool electrode 6. Figure 7 As shown, the brushes and slip ring track serve to connect to the power supply and fix the axial movement of the tool electrode 6. Both the lower stator coil 4 and the workpiece 17 can be powered by a fixed connection.

[0047] The circuit consists of the following components: Coil circuit: Induction coil 9 forms its own circuit. Electrode plate circuit: Electrostatic drive stator plate, electrostatic drive mover plate 3, and electrostatic drive power supply form the circuit. Electrolytic machining circuit: Workpiece 17, tool electrode 6, and electrolytic pulse power supply 16 form the circuit. Circuit protection resistors 21 are required for the coil circuit, electrode plate circuit, and electrolytic machining circuit to prevent accidental short circuits from damaging the instrument.

[0048] The processing procedure of the electrolytic processing apparatus of the present invention is as follows.

[0049] During the machining process, an electrostatically driven micro-feed actuator based on magnetic levitation support is mounted on the macro-feed machine tool 14, such as... Figure 6As shown. First, the magnetic levitation power supply is turned on. The tool electrode 6 rises a small distance with the electrostatically driven moving electrode plate 8 until it stabilizes, and the electrostatically driven moving electrode plate 8 is within the effective range of the electrostatically driven stator electrode plate 2. Next, the tool electrode 6 and the workpiece 17 are connected to the two stages of the machining power supply, respectively. The macro-feed machine tool 14 feeds at a constant speed until the distance between the tool electrode 6 and the workpiece 17 reaches the electrolytic machining gap, thus forming a current path through the electrolyte 19. The electrostatic drive power supply is then turned on, and the voltage applied to the electrostatic drive electrode plates (stator and moving electrode) is controlled by the machining power supply, making the machining and electrostatic drive synchronized. The pulse signal of the machining power supply simultaneously controls the electrostatic drive power supply. When the machining power supply applies a high-voltage pulse to the electrode gap, the voltage applied by the electrostatic drive power supply to the electrostatic drive electrode plate is also high. Under the action of electrostatic force, the distance between the electrostatic drive moving electrode plate 8 and the electrostatic drive stator electrode plate 2 increases, driving the tool electrode 6 to make a micro-feed. When the machining power supply applies a low-voltage pulse to the electrode gap, the voltage applied by the electrostatic drive power supply to the electrostatic drive moving electrode plate 8 and the electrostatic drive stator electrode plate 2 is low. When the electrostatic force decreases or even becomes zero, the electrostatic drive moving electrode plate 8 retracts to the equilibrium state under the action of magnetic levitation force, and the tool electrode 6 retracts. In this way, the tool electrode 6 performs one forward and one backward movement in each machining pulse, compressing and stretching the flow field in the machining gap, which is beneficial for the renewal of electrolyte 19 and the removal of waste chips.

[0050] Compared with other high-frequency ultrasonic oscillators, the electrolytic machining device of this invention has the advantages of less obvious thermal effect and fast amplitude modulation response. When applied to the field of auxiliary electrolytic machining, it can effectively eliminate problems such as bubble adhesion, impurity accumulation and poor electrolyte circulation during the electrolysis process. It has a significant improvement effect on the machining of complex three-dimensional structures such as deep small holes, and can significantly improve the machining speed and stability, reduce stray effects, and significantly improve the accuracy of electrolytic machining.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural changes made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A micro-feed actuator driven by electrostatic levitation support, characterized in that, include: Housing, electrostatic drive stator electrode plate, electrostatic drive mover, stator coil, inner shaft and tool electrode; The electrostatic drive stator electrode plate, electrostatic drive mover, stator coil, and inner shaft are coaxially arranged inside the housing; The electrostatic drive stator electrode plate is fixedly disposed on the top of the housing, the stator coil is fixedly disposed inside the housing, the electrostatic drive mover is suspended between the electrostatic drive stator electrode plate and the stator coil, the top of the inner shaft passes through the stator coil and is fixedly connected to the electrostatic drive mover, and the bottom of the inner shaft passes through the housing and is connected to the tool electrode. The electrostatic drive actuator includes an electrostatic drive actuator electrode plate, an induction coil, and a permanent magnet arranged sequentially from top to bottom. The inner shaft passes through the permanent magnet and the induction coil and is fixedly connected to the electrostatic drive actuator electrode plate.

2. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, A linear limiting bearing is provided at the bottom of the outer casing, and the inner shaft passes through the linear limiting bearing.

3. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, The stator coil is a stator coil with an internal iron-nickel alloy.

4. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, The induction coil is a copper induction coil.

5. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, The inner shaft is a smooth, hollow structure.

6. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, The outer casing is also provided with an electrical connection hole.

7. The electrostatically driven micro-feed actuator based on magnetic levitation support according to claim 1, characterized in that, The top of the outer casing is provided with a mounting post.

8. An electrolytic processing apparatus, characterized in that, The electrolytic machining apparatus includes an electrostatically driven micro-feed actuator based on magnetic levitation support as described in any one of claims 1 to 7.

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