Flexible braided electrode and electrochemical polishing complex inner channel method

Abstract

The application provides a flexible braided electrode and an electrochemical polishing method for a complex inner channel and belongs to the technical field of electrolytic processing. The flexible braided electrode is formed by mutually braiding a plurality of flexible conductive wires and a plurality of flexible insulating wires according to a certain interval, and the diameter of the insulating wires is greater than that of the conductive wires, and a certain height step is naturally formed between the insulating wires and the conductive wires, so that short-circuit burn caused by the contact between the conductive wires and the inner channel can be avoided, mass transfer can be enhanced, and product discharge can be accelerated; the flexible braided electrode has a hollow net-like cylindrical structure, can realize inner-outer composite liquid flushing, and improves the flushing effect. During polishing, the flexible braided electrode can be self-adaptively bent and deformed in the curved inner channel, realizes inner-outer composite liquid flushing by using the inner-outer through characteristics, and realizes electrochemical polishing of the complex inner channel by combining electrode rotation and reciprocating motion. The application provides a flexible braided electrode with a clever concept, and an innovative process method is additionally provided, so that efficient and high-quality finishing of the complex inner channel can be realized.

Description

Technical Field

[0001] This invention relates to a flexible braided electrode and a method for electrochemical polishing complex internal channels, belonging to the field of electrochemical processing technology. Background Technology

[0002] Additive manufacturing is a technology that uses computer-aided design software to create models, and then heats and melts materials using methods such as lasers to stack them point by point, line by line, and layer by layer to form complete parts or components. This technology offers high flexibility, short manufacturing cycles, and significantly reduces material waste, making it widely used in aerospace manufacturing, personalized medical implants, and chemical catalysis. Furthermore, the flexibility and efficiency of additive manufacturing make it widely applicable in the fabrication of workpieces with complex internal channel structures.

[0003] However, due to issues such as spheroidization, powder adhesion, and step effects in additive manufacturing, the resulting parts have rough surfaces and numerous protrusions, making them difficult to meet the technical requirements of fields like aerospace. Therefore, post-finishing finishing is necessary. This is especially true for complex internal channels, where poor visibility and inconvenient tooling further complicate the finishing process. How to perform finishing on workpieces with complex, curved internal channels remains a significant challenge in manufacturing.

[0004] Currently, common polishing processes for additive manufacturing parts both domestically and internationally include mechanical polishing, laser polishing, abrasive flow polishing, and chemical polishing. Among these polishing technologies, mechanical polishing is the most widely used, offering significant advantages in material removal efficiency and post-processing surface quality. However, mechanical polishing involves numerous processing steps, has poor tool accessibility, and cannot effectively smooth complex internal channels. During laser polishing, localized heating of the workpiece in a short period may cause deformation or cracks, and the laser beam struggles to handle complex internal channels. After abrasive flow polishing, abrasive particles may remain on the workpiece surface, and these particles are even more difficult to remove from internal channels, making it difficult to precisely control the surface roughness of the workpiece.

[0005] Electrochemical polishing, as a non-contact processing method, is not limited by the mechanical properties of materials. It mainly relies on anodic dissolution during the electrochemical reaction to achieve the purpose of material removal. This method has the advantages of high flexibility and good processing effect, and can better realize the finishing of complex internal channels.

[0006] The patent "Flexible Wire Electrode Assembly and Method for Composite Polishing of Inner Surface of Micro-Metal Flow Channels" (Application No. 20020010932152.0, Applicant: Nanjing University of Aeronautics and Astronautics, Inventors: Zeng Yongbin, Li Yanliang, Yang Tao, Xu Zhengyang) proposes a flexible electrode made of two flexible wires spirally wound together, with the diameter of the insulating flexible wire being larger than that of the conductive cathode wire, thus avoiding short circuits caused by the conductive cathode wire contacting the inner wall. In contrast, the flexible braided electrode used in this invention has a hollow structure, allowing for internal and external composite flushing, accelerating product discharge, improving polishing quality, and enabling the cross-sectional shape of the flexible electrode to be adjusted according to the shape of the inner channel, thus completing the polishing of square, elliptical, and other inner channels.

[0007] The patent "Electrolytic Mechanical Finishing Method for Traction-Type Flexible Tool Cathode and Internal Channel" (application number 2001810474066.2, applicant: Nanjing University of Aeronautics and Astronautics, inventors: Qu Ningsong, Yue Xiaokang, Fang Xiaolong, Li Hansong) proposes a cathode tool comprising a cathode bolt and a flexible friction layer, which finishes the inner wall surface through a combination of electrolysis and friction. In comparison, the flexible braided electrode structure used in this invention is simple, lightweight, and has high polishing efficiency, while also enabling finishing of even smaller internal channels.

[0008] The patent "Flexible Twisted Cathode and Electrochemical Polishing Method for Complex Inner Channels" (Application No. 2002210578163.2, Applicant: Nanjing University of Aeronautics and Astronautics, Inventors: Zhu Di'an, Lin Chao, Wang Dengyong) proposes a flexible electrode made of two metal wires and multiple strands of non-conductive microfilaments twisted together. The non-conductive microfilaments, evenly distributed along the circumference, prevent direct contact between the tool cathode and the inner channel, thus preventing short circuits. In contrast, the flexible braided electrode used in this invention has a mesh-like hollow structure, allowing for internal and external composite flushing. The alternating weaving method naturally creates height steps between the insulating wires and the metal conductor wires, ensuring a smooth finish while preventing short circuits.

[0009] The patent "Combined Electrolytic Grinding Processing Method for Complex Internal Channels" (application number 20020011047082.7, applicant: Nanjing University of Aeronautics and Astronautics, inventors: Zhu Di, Wang Dengyong, An Linchao) proposes a processing method that uses a hollow flexible shaft to pull a tool assembly in reciprocating motion to achieve electrolytic grinding composite processing, used for finishing the surface of curved complex internal channels. In comparison, the flexible braided electrode structure used in this invention is simple, easy to manufacture, and can finish internal channel parts with smaller dimensions.

[0010] The patent "Flexible Electrode for Electrochemical Polishing and Electrochemical Polishing Method with Internal Cavity Structure" (application number 2002110339643.9, applicant: Institute of Mechanical Manufacturing Technology, China Academy of Engineering Physics, inventors: Ye Zuoyan, Ye Minheng, Wang Lili, Pan Jinlong, Li Xiaoyuan, Wang Chao, Shen Xianfeng) proposes a flexible electrode composed of an insulating layer, an electrode layer, and a support layer. After expansion, it can adaptively match the internal cavity structure morphology under the action of the workpiece's inner wall for electrochemical polishing. In comparison, this invention adopts a high-voltage, high-speed electrolyte flushing flow field mode and controls the cathode to perform reciprocating and rotating motions, which is more conducive to product discharge, enhances mass transfer, and ensures a smooth finishing effect.

[0011] The patent "Snake-shaped Flexible Cathode and Electrochemical Polishing Method for Internal Channels" (application number 202210578582.6, applicant: Nanjing University of Aeronautics and Astronautics, inventors: Zhu Di'an, Lin Chao, Wang Dengyong) proposes a snake-shaped flexible cathode composed of multiple cathode unit sections, ball joints, cathode end caps, cathode support rings, and fastening bolts. In contrast, the flexible braided electrode used in this invention is woven from multiple smaller diameter metal wires and multiple larger diameter non-metal wires arranged at certain intervals. It has a simple structure, is easy to manufacture, and can be used for the finishing of small-diameter internal channels.

[0012] The patent "An Electrolytic Cleaning Electrode Device and Processing Method for Inner Flow Channels of Additively Manufactured Parts" (Application No. 2002310072363.5, Applicant: Shanghai Jiao Tong University, Inventor's Name Not Published) provides an electrode structure consisting of a front conductive electrode, a front insulating sleeve, and a rear flexible electrode, with residue removed by a rear brush. In contrast, the flexible braided electrode used in this invention features a hollow structure that allows for internal and external composite fluid flushing, enhancing mass transfer and improving the quality of electropolishing.

[0013] The patent "An Electrolytic Polishing Device for the Inner Wall of Irregularly Shaped Microtubes" (application number 2002310330372.X, applicant: Taiyuan University of Technology, inventors: Liang Guoxing, Bai Xuechen, Hao Xinhui, Liu Donggang, Yang Shiqing, Zhang Dongdong, Lü Ming) designs an electrolytic polishing device for the inner wall of irregularly shaped microtubes, comprising an electrolyte tank, a waste liquid tank, and a reaction chamber. Electrolytic polishing of the inner hole of the irregularly shaped microtubes is achieved through a redirecting pulley and a driving device. In contrast, the flexible braided electrode structure used in this invention is simple, employs a combined internal and external flushing mode combined with mechanical motion for finishing, and the product can be quickly discharged with the electrolyte, resulting in a good finishing effect.

[0014] The patent "Suction-type Electrolytic Machining Device and Method for Finishing Internal Structures" (Application No. 202011451556.4, Applicant: Nanjing University of Aeronautics and Astronautics, Inventors: Tang Xiaochuan, Zhao Chenhao, Qu Ningsong) designs a suction-type electrolytic machining device with a tool cathode, insulating layer, clamping frame, slider, bolt, sealing gasket, liquid extraction tube, and clamping screw to achieve electrolytic finishing of the entire internal structure surface. In contrast, the flexible braided electrode used in this invention can be rolled into a circle, ellipse, or square shape according to the shape of the inner hole cross-section, and can process complex internal channel surfaces with non-circular cross-sections.

[0015] As mentioned above, electrochemical polishing primarily relies on the tool cathode extending into the inner channel to perform an electrochemical reaction. However, due to the small diameter and significant curvature of the inner channel, problems arise during actual processing, such as difficulty in machining the curved sections, inability to promptly remove processed products, and short circuits occurring when the tool cathode contacts the workpiece. Therefore, designing a flexible tool cathode that is flexible, simple in structure, and capable of effectively electrochemical polishing complex inner channels while avoiding short-circuit burns is a critical issue that urgently needs to be addressed. Summary of the Invention

[0016] This invention addresses the problem that the tool cathode cannot extend into the curved channel and the processed product cannot be discharged in time when electrochemically polishing workpieces with complex internal channels. It proposes a flexible braided electrode with good flexibility and simple structure, which can effectively realize the electrochemical polishing of complex internal channels and a method for electrochemical polishing complex internal channels.

[0017] A flexible braided electrode is characterized by being woven into a hollow mesh structure by alternating flexible insulating wires and flexible conductive wires; wherein the diameter of the flexible insulating wires is larger than the diameter of the flexible conductive wires, and after weaving, steps of a certain height are naturally formed between them, which can not only avoid short circuit burns caused by contact between the conductive wires and the inner channels, but also enhance mass transfer and accelerate product discharge.

[0018] The method for electrochemical polishing complex internal channels using a flexible braided electrode is characterized by the following steps: Step 1: Fix the workpiece to be processed on the machine tool worktable, with one end of the internal channel connected to the liquid collection chamber; Step 2: Place the flexible braided electrode along the internal channel into the workpiece, allowing it to adaptively bend and deform according to the shape of the internal channel; connect one end of the flexible braided electrode to the first spindle of the machine tool and the other end to the second spindle, adjusting the machine tool spindle to the initial processing position; Step 3: Connect the flexible braided electrode to the negative terminal of the power supply, and connect the workpiece to the positive terminal of the power supply; Step 4: Turn on the liquid supply system, allowing a portion of the electrolyte to flow in from the inner hole of the flexible braided electrode through the supply end coaxial with the machine tool spindle, and then flow into the processing gap between the flexible braided electrode and the surface of the internal channel of the workpiece through the mesh gap formed between the flexible insulating wire and the flexible conductive wire; another portion of the electrolyte flows into the liquid collection chamber and enters the processing gap along the outer wall of the flexible braided electrode. This forms an internal and external composite flushing fluid; the diameter of the insulating wire of the flexible braided electrode is larger than the diameter of the conductive wire, avoiding short circuit burns caused by the contact between the conductive wire of the flexible braided electrode and the surface of the inner channel of the part during processing; Step 5: After the electrolyte fills the inner channel, turn on the power and control the machine tool spindle to perform reciprocating motion along the axis and rotational motion around the axis, driving the flexible braided electrode to perform reciprocating motion and rotational motion. Under the combined action of electrochemical dissolution and the mechanical motion of the flexible electrode, the electrochemical dissolution of the surface of the inner channel of the anode workpiece to be processed is achieved. Moreover, the protruding area on the surface of the inner channel is closer to the flexible braided electrode, and the electrochemical dissolution speed is higher, which plays a leveling role. At the same time, the electrochemical reaction products and bubbles are quickly discharged under the combined action of electrolyte flushing and the movement of the flexible braided electrode, realizing electrolytic polishing of the surface of the inner channel of the part; Step 6: After a period of time, when the roughness of the surface of the inner channel of the part reaches the processing requirements, the processing is stopped.

[0019] The beneficial effects of this invention are as follows:

[0020] 1) An innovative tool electrode structure is provided. The flexible braided electrode proposed in this invention consists of a hollow mesh structure formed by alternating flexible insulating wires and flexible conductive wires; wherein the diameter of the flexible insulating wires is larger than the diameter of the flexible conductive wires, and after the braiding is completed, steps of a certain height are naturally formed between them, which can not only avoid short circuit burns caused by contact between the conductive wires and the inner channels, but also enhance mass transfer and accelerate product discharge.

[0021] 2) This invention provides an innovative polishing process. When using a flexible braided electrode for internal channel electrochemical polishing, the flexible braided electrode rotates around an axis and reciprocates. Simultaneously, utilizing the mesh structure of the flexible braided electrode and employing an internal and external composite flushing mode, mass transfer is enhanced, processing products are removed, and polishing efficiency and quality are improved.

[0022] 3) It has a wide range of applications. The flexible braided electrode proposed in this invention can change the braiding method and the density of the braid, and can be rolled into a circle, ellipse or square shape along the axis to adapt to the polishing of complex internal channels with different cross-sectional shapes such as round holes, elliptical holes and square holes, and has a wide range of applications.

[0023] The flexible braided electrode is characterized in that it is a single-strand braided structure, consisting of alternating single-strand flexible insulating wires and single-strand flexible conductive wires. The braiding method is simple and easy to manufacture.

[0024] The flexible braided electrode is characterized by a three-strand braided structure, consisting of two-strand flexible insulating wires and a single-strand flexible conductive wire interlaced side-by-side; each flexible conductive wire is adjacent to two flexible insulating wires on both sides. This arrangement of two insulating wires on both sides better accommodates internal channels with greater curvature and more complex structures, avoiding point contact short circuits caused by abrupt changes in the internal wall structure during processing, thus ensuring processing stability.

[0025] The flexible braided electrode is characterized by having a positive braided structure, i.e., with the direction of the braided yarn as the curling axis. This structure is easy to fabricate electrodes with complex cross-sections and has low manufacturing difficulty.

[0026] The flexible braided electrode is characterized by a 45° oblique braiding structure, where the direction forming a 45° angle with the braiding filaments serves as the curling axis. This structure provides uniform stress during bending, exhibits good material mechanical properties, and can handle internal channel structures with greater curvature.

[0027] The flexible braided electrode is characterized in that the flexible insulating wires and flexible conductive wires are arranged alternately in both the warp and weft directions. This method ensures both the rigidity and deformability of the flexible braided electrode; furthermore, it avoids contact between the conductive metal wires and the inner wall of the workpiece, preventing short-circuit burns.

[0028] The flexible braided electrode is characterized in that: the cross-section of the flexible braided electrode is circular, elliptical, or square, and can be selected according to different processing objects, taking into account both rigidity and flexibility. Attached Figure Description

[0029] Figure 1 A schematic diagram of the overall cathode of the flexible braided electrode;

[0030] Figure 2 A schematic diagram of the electrochemical polishing process for complex internal channels of flexible braided electrodes;

[0031] Figure 3Flexible braided electrodes made with different braiding methods are a single-strand positive braided structure and a three-strand positive braided structure.

[0032] Figure 4 A schematic diagram of a positive braided structure in which a flexible braided electrode is curled along the axis of the braided filaments;

[0033] Figure 5 A schematic diagram of a 45° oblique braided structure in which a flexible braided electrode is curled along an axis that forms a 45° angle with the braided filaments;

[0034] Figure 6 Flexible braided electrodes with different cross-sectional shapes, namely circular, elliptical, and square;

[0035] The labels in the diagram are as follows: 1. Flexible braided electrode; 2. Flexible insulating wire; 3. Flexible conductive wire; 4. Part to be processed; 5. First spindle of the machine tool; 6. Liquid collection chamber; 7. Surface of the inner channel of the part; 8. Power supply; 9. Second spindle of the machine tool. Detailed Implementation

[0036] The present invention will now be further described with reference to the accompanying drawings.

[0037] like Figures 1-2 As shown, the method for electrochemical polishing of complex internal channels using flexible braided electrodes proposed in this invention includes the following steps:

[0038] Step 1: Fix the part 4 to be processed on the machine tool worktable, with one end of the inner channel connected to the liquid collection chamber 6;

[0039] Step 2: Place the flexible braided electrode 1 along the inner channel into the workpiece 4 to be processed, and it will bend and deform adaptively according to the shape of the inner channel; one end of the flexible braided electrode 1 is connected to the first spindle 5 of the machine tool, and the other end is connected to the second spindle 9 of the machine tool, and adjust the machine tool spindle to the initial processing position;

[0040] Step 3: Connect the flexible braided electrode 1 to the negative terminal of power supply 8, and connect the part to be processed 4 to the positive terminal of power supply 8;

[0041] Step 4: Turn on the electrolyte supply system. A portion of the electrolyte flows into the inner hole of the flexible braided electrode 1 through the supply end coaxial with the machine tool spindle 5, and flows into the machining gap between the flexible braided electrode 1 and the inner channel surface 7 of the part through the mesh gap formed between the flexible insulating wire 2 and the flexible conductive wire 3. Another portion of the electrolyte flows into the liquid collection chamber 6 and enters the machining gap along the outer wall of the flexible braided electrode 1, thus forming an internal and external composite flushing liquid. The diameter of the flexible braided electrode insulating wire 2 is larger than the diameter of the conductive wire 3, which avoids short circuit and burn when the flexible braided electrode conductive wire 3 comes into contact with the inner channel surface 7 of the part during the machining process.

[0042] Step 5: After the electrolyte fills the inner channel, turn on the power supply 8 and control the machine tool spindle 5 to perform reciprocating motion along the axis and rotational motion around the axis, which drives the flexible braided electrode 1 to perform reciprocating motion and rotational motion. Under the combined action of electrochemical dissolution and the mechanical motion of the flexible electrode 1, the electrochemical dissolution of the inner channel surface 7 of the anode workpiece to be processed is achieved. The raised area of ​​the inner channel surface 7 is closer to the flexible braided electrode 1, and the electrochemical dissolution speed is higher, which has a leveling effect. At the same time, the electrochemical reaction products and bubbles are quickly discharged under the combined action of electrolyte flushing and the movement of the flexible braided electrode 1, realizing electrolytic polishing of the inner channel surface of the part.

[0043] Step Six: After a period of time, when the roughness of the inner channel surface 7 of the part meets the processing requirements, stop processing.

[0044] like Figure 3 As shown, the flexible braided electrode proposed in this invention can be made by interlacing single-strand insulating wire 2 and single-strand metal conductor wire 3; or it can be made by interlacing double-strand insulating wire 2 and single-strand metal conductor wire 3 side by side.

[0045] like Figure 4 , Figure 5 As shown, in terms of the curling method, the flexible braided electrode 1 of the present invention can be curled along the direction of the braided filament as the axis, or curled along the direction at a 45° angle to the braided filament as the axis.

[0046] like Figure 6 As shown, the cross-sectional shape of the flexible braided electrode proposed in this invention after curling can be determined according to the cross-sectional shape of the inner channel to be processed, so as to meet the processing requirements of inner channels of different shapes, such as circles, ellipses, squares, etc.

Claims

1. A flexible braided electrode, characterized in that: A hollow mesh structure is formed by alternating arrangement and weaving of several flexible insulating wires (2) and several flexible conductive wires (3); wherein the diameter of the flexible insulating wires (2) is larger than the diameter of the flexible conductive wires (3), and after weaving, a certain height of steps are naturally formed between them, which can not only avoid short circuit and burn when the conductive wires come into contact with the inner channel, but also enhance mass transfer and accelerate product discharge. The braided structure of the above-mentioned flexible braided electrode (1) is a single-strand braided structure, that is, a single-strand flexible insulating wire (2) and a single-strand flexible conductive wire (3) are interwoven; or a three-strand braided structure, that is, a double-strand flexible insulating wire (2) and a single-strand flexible conductive wire (3) are interwoven side by side; each flexible conductive wire (3) has two flexible insulating wires (2) closely adjacent to its two sides.

2. The flexible braided electrode according to claim 1, characterized in that: The flexible braided electrode (1) has a positive braided structure, that is, the direction of the braided filament is used as the curling axis.

3. The flexible braided electrode according to claim 1, characterized in that: The flexible braided electrode (1) has a 45° oblique braided structure, that is, the direction at a 45° angle with the braided wire is used as the curling axis.

4. The flexible braided electrode according to claim 1, characterized in that: The flexible insulating wire (2) and the flexible conductive wire (3) are arranged alternately in both the warp and weft directions.

5. The flexible braided electrode according to claim 1, characterized in that: The cross-section of the above-mentioned flexible braided electrode (1) is circular, elliptical, or square.

6. The method for electrochemical polishing of complex internal channels using the flexible braided electrode as described in claim 1, characterized in that... Includes the following processes: Step 1: Fix the part to be processed (4) on the machine tool workbench, and connect one end of the inner channel to the liquid collection chamber (6); Step 2: Place the flexible braided electrode (1) along the inner channel into the part to be processed (4), and it will bend and deform adaptively according to the shape of the inner channel; One end of the flexible braided electrode (1) is connected to the first spindle (5) of the machine tool, and the other end is connected to the second spindle (9) of the machine tool. Adjust the machine tool spindle to the initial machining position. Step 3: Connect the flexible braided electrode (1) to the negative terminal of the power supply (8), and connect the part to be processed (4) to the positive terminal of the power supply (8); Step 4: Turn on the liquid supply system. Part of the electrolyte flows into the inner hole of the flexible braided electrode (1) through the liquid supply end coaxial with the first spindle (5) of the machine tool, and flows into the processing gap between the flexible braided electrode (1) and the inner channel surface (7) of the part through the mesh gap formed between the flexible insulating wire (2) and the flexible conductive wire (3); another part of the electrolyte flows into the liquid collection chamber (6) and enters the processing gap along the outer wall of the flexible braided electrode (1), thereby forming an internal and external composite flushing liquid; the diameter of the flexible insulating wire (2) is larger than the diameter of the flexible conductive wire (3), which avoids short circuit and burn when the flexible conductive wire (3) contacts the inner channel surface (7) of the part during the processing; Step 5: After the electrolyte fills the inner channel, turn on the power supply (8) and control the first spindle (5) of the machine tool to perform reciprocating motion along the axis and rotational motion around the axis, which drives the flexible braided electrode (1) to perform reciprocating motion and rotational motion. Under the combined action of electrochemical dissolution and the mechanical motion of the flexible braided electrode (1), the electrochemical dissolution of the surface (7) of the inner channel of the part is achieved. The protruding area of ​​the surface (7) of the inner channel of the part is closer to the flexible braided electrode (1), and the electrochemical dissolution speed is higher, which plays a leveling effect. At the same time, the electrochemical reaction products and bubbles are quickly discharged under the combined action of electrolyte flushing and the movement of the flexible braided electrode (1), realizing the electrolytic polishing of the surface of the inner channel of the part. Step 6: After a period of time, when the roughness of the inner channel surface (7) of the part reaches the processing requirements, stop processing.

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