An electrolytic milling system with oxygen-enriched liquid mist and pulsed airflow.

Abstract

This invention relates to an electrolytic milling system employing a combined oxygen-enriched liquid mist and pulsating airflow spray, belonging to the field of electrolytic grinding composite machining. By utilizing a high-speed jetting method of oxygen-enriched liquid mist electrolyte supply, a continuous electrolyte film capable of forming a conductive circuit between the workpiece anode and the milling tool cathode exists only within the machining gap, effectively suppressing stray currents and significantly improving machining accuracy. Within the machining gap, the combined effect of externally introduced oxygen and oxygen electrolytically released within the gap significantly accelerates anode film formation. Because the anode film is much easier to remove by abrasive grains than the substrate of difficult-to-machine workpiece materials, this effectively solves the problems of obvious mechanical wear marks and severe milling tool wear caused by excessive mechanical tilling and scratching of the substrate in conventional electrolytic milling finishing, improving surface quality and extending the service life of the milling tool. The integrated nozzle of this invention combines the oxygen-enriched liquid mist nozzle for supplying electrolyte and the air nozzle for removing machining products from the milling tool surface, improving the flexibility, machining stability, and machining efficiency of the electrolytic milling system.

Description

Technical Field

[0001] This invention relates to an electrolytic milling and grinding system that combines oxygen-enriched liquid mist and pulsating airflow, belonging to the field of electrolytic milling and grinding composite machining. Background Technology

[0002] Electrolytic milling integrates the advantages of electrolytic machining, grinding, and CNC milling, offering higher machining accuracy and efficiency than pure electrolytic milling. It has become a novel electrolytic-mechanical composite machining method that has garnered significant attention in recent years. Electrolytic milling offers numerous advantages in precision machining of difficult-to-machine and easily electrochemically passivated alloy materials such as stainless steel, amorphous alloys, and titanium alloys. However, current methods typically employ direct electrolyte spraying and immersion for these challenging materials, resulting in less than ideal machining outcomes. This is primarily because these methods create a continuous conductive circuit between the sprayed electrolyte and the tool cathode, leading to stray current corrosion and severe overcutting. This significantly limits the application of electrolytic milling in the efficient and precise machining of these difficult-to-machine materials.

[0003] To address this issue, Li Hansong from Nanjing University of Aeronautics and Astronautics proposed an auxiliary anode electrolytic milling system and method (patent application number: 201610852155.7). This method involves connecting an auxiliary anode, coated with an inert metal insoluble in the electrolyte, directly behind the tool cathode in the feed direction. Applying a positive potential difference suppresses stray corrosion on the machined surface, reduces overcutting, and improves machining accuracy. However, this patented solution (patent application number: 201610852155.7) still has certain limitations: First, while the auxiliary anode reduces stray current, it cannot fundamentally eliminate it by controlling the flow field. Second, the connection of the auxiliary anode restricts the tool cathode's feed direction, reducing the flexibility of electrolytic milling. Third, when using this solution for finishing electrolytic milling at lower voltages, the machined surface shows obvious wear marks, poor surface quality, and severe tool wear.

[0004] In addition, in his 2018 doctoral dissertation at Nanjing University of Aeronautics and Astronautics entitled "Basic Research on Electrolytic Machining Technology of High-Temperature Alloy Casings", Ge Yongcheng used a gas insulation method of injecting high-pressure gas into the machined surface to protect the machined surface of the internal liquid-sprayed electrolytic grinding, preventing secondary corrosion of the smooth and flat electrolytic grinding surface obtained under the assistance of mechanical grinding. The experiment achieved good processing results. However, the nozzle in this method has a relatively simple function and does not integrate a nozzle for removing the processed products. It is not suitable for electrolytic grinding of amorphous alloys that generate refractory products that easily adhere to milling tools during electrolytic machining. Furthermore, the internal liquid-sprayed electric spindle increases the development and maintenance costs of electrolytic grinding composite machining tools.

[0005] Currently, the use of spray-based liquid supply for micro-lubrication and cooling in machining processes has received widespread attention and is highly valuable for electrolytic milling. Therefore, based on the above issues, this invention proposes an oxygen-enriched liquid mist-pulsated airflow co-spray electrolytic milling system for difficult-to-machine alloys such as titanium alloys and amorphous alloys, which are prone to passivation and the generation of large amounts of insoluble viscous products during electrolytic machining. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of conventional electrolytic milling processes for difficult-to-machine alloy materials such as titanium alloys and amorphous alloys, which suffer from severe stray corrosion leading to low roughing accuracy, frequent short-circuit discharges due to the generation of a large number of insoluble products adhering to the milling tool and workpiece surface, obvious grinding marks on the finished surface, and severe wear of the milling tool. This invention proposes an electrolytic milling system that combines oxygen-enriched liquid mist and pulsating airflow.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is: an electrolytic milling system for simultaneous spraying of oxygen-enriched liquid mist and pulsed airflow, comprising a workpiece, a power supply, a milling tool, and a control switch, characterized in that: it further comprises an integrated nozzle, an oxygen-enriched liquid mist stream, and an air stream; the integrated nozzle is provided with an oxygen-enriched liquid mist nozzle and an air nozzle side by side; the oxygen-enriched liquid mist stream is sprayed from the oxygen-enriched liquid mist nozzle; the air stream is sprayed from the air nozzle at high speed in a periodic pulse manner; the oxygen-enriched liquid mist stream is sprayed toward the angle between the circumferential surface of the milling tool and the machined surface; the air stream is sprayed toward the circumferential surface of the milling tool; the oxygen volume ratio in the oxygen-enriched liquid mist stream is greater than 50%; the air stream ejection velocity is greater than 10 m / s, and the spray frequency and interval are adjustable; the droplet size in the oxygen-enriched liquid mist stream is 5-20 μm; the oxygen-enriched liquid mist nozzle and the air nozzle are physically separated from each other.

[0008] The liquid in the oxygen-enriched liquid mist is an acidic or neutral electrolyte containing oxygen elements, such as H2SO4 solution or NaNO3 solution, with a mass percentage concentration of 10-40 wt.%.

[0009] The abrasive grains in the milling tool are diamond or polycrystalline boron nitride with a particle size of 40-100μm, and the binder is a metal binder.

[0010] The positive terminal of the power supply is electrically connected to the workpiece via a control switch, and the negative terminal is electrically connected to the milling tool.

[0011] The distance between the integrated nozzle and the milling tool is adjustable.

[0012] Compared with existing processing systems, the present invention has the following advantages:

[0013] 1. High machining accuracy and low electrolyte consumption. This invention employs a high-speed jetting atomized electrolyte supply method. Because the atomized liquid impacts the wall at the angle between the milling tool and the workpiece surface to be machined, forming a small-scale liquid film, a continuous electrolyte film cannot be formed on the machined surface. This ensures that a continuous electrolyte film exists only within the machining gap, allowing a conductive circuit to be formed between the workpiece anode and the milling tool cathode. A conductive circuit cannot be formed between the non-machined area of ​​the workpiece and the milling tool. Therefore, stray currents are completely suppressed, achieving highly localized material removal and effectively improving machining accuracy, while significantly reducing electrolyte consumption.

[0014] 2. Excellent surface finish and long service life of milling tools. By spraying a high-oxygen-content oxygen-enriched mist electrolyte onto the angle between the milling tool and the workpiece surface, an oxygen-enriched electrolyte film forms within the machining gap. The combined effect of externally introduced oxygen and oxygen electrolytically released within the machining gap significantly accelerates anodic film formation. Because the anodic film generally has a loose structure, it is much easier for abrasive grains to scrape off than the substrate of difficult-to-machine workpiece materials. This effectively solves the problem of obvious mechanical wear marks and severe tool wear caused by excessive mechanical tilling and scratching of the substrate in conventional electrolytic milling finishing, thus improving surface finish and extending the service life of the milling tools.

[0015] 3. High integration, good processing flexibility, stable processing, and high processing efficiency. The integrated nozzle of this invention integrates the oxygen-rich liquid mist nozzle for supplying electrolyte and the air nozzle for removing processing products from the surface of the milling tool, improving the flexibility of the electrolytic milling system. At the same time, during the electrolytic milling process using this invention, a large amount of insoluble processing products adhering to the surface of the milling tool are rapidly removed by the impact of the high-speed pulsed airflow, avoiding the short-circuit discharge phenomenon commonly found in conventional electrolytic milling processes, and effectively improving processing stability and efficiency. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the electrolytic milling system of the present invention, which uses oxygen-enriched liquid mist and pulsed airflow for simultaneous spraying.

[0017] Figure 2 This is an electric field distribution diagram of a plane machined by conventional liquid spraying electrolytic milling.

[0018] Figure 3 This is a schematic diagram illustrating the principle of electrolytic milling of a plane using an electrolytic milling system employing an oxygen-enriched liquid mist and pulsating airflow co-spraying method as described in this invention.

[0019] Figure 4 This is an electric field distribution diagram of a plane being machined using an electrolytic milling system employing an oxygen-enriched liquid mist and pulsating airflow spraying method as described in this invention.

[0020] Figure 5 This is a schematic diagram illustrating the reaction principle of the machining area in an electrolytic milling system employing an oxygen-enriched liquid mist and pulsed airflow spraying method as described in this invention.

[0021] The labels in the diagram are as follows: 1. Workpiece; 2. Machining path; 3. Integrated nozzle; 4. Airflow; 5. Oxygen-enriched liquid mist; 6. Milling tool rotation direction; 7. Power supply; 8. Control switch; 9. Milling tool; 10. Oxygen-enriched liquid mist nozzle; 11. Air nozzle; 12. Anode film; 13. Processed product; 14. Surface being processed; 15. Oxygen-enriched electrolyte film; 16. Processed surface; 17. Oxygen in the liquid mist; 18. Electrolyte microdroplets; 19. Processed product debris; 20. Feed direction; 21. Abrasive grains; 22. Surface to be processed; 23. Oxygen generated during electrolysis; 24. Current line; 25. Ordinary electrolyte nozzle; 26. Ordinary electrolyte film. Detailed Implementation

[0022] The implementation of this invention patent will be further described below with reference to the accompanying drawings, and the purpose, technical solution and advantages of this invention patent will be explained more clearly by taking electrolytic milling of a flat surface as an example.

[0023] like Figure 1As shown, an electrolytic milling system for co-spraying oxygen-enriched liquid mist and pulsed airflow includes a workpiece 1 (zirconium-based amorphous alloy), an integrated nozzle 3 that integrates an oxygen-enriched liquid mist nozzle 10 and an airflow nozzle 11, an airflow 4, an oxygen-enriched liquid mist flow 5 composed of electrolyte microdroplets 18 and oxygen 17 in the liquid mist, a power supply 7, a milling tool 9 driven by a machine tool spindle (not shown), and a control switch 8. The positive terminal of the power supply 7 is connected to the workpiece 1 via the control switch 8, and the negative terminal is connected to the milling tool 9. The horizontal distance between the integrated nozzle 3 and the milling tool 9 is 100 mm. The oxygen-enriched liquid mist flow 5 is sprayed towards the angle between the circumferential surface of the milling tool 9 and the machined surface 16. The airflow 4 is sprayed at high speed from the air nozzle 11 in a periodic pulse manner towards the circumferential surface of the milling tool 9. The spray direction of the airflow 4 is opposite to the rotation direction of the milling tool 9, while the spray direction of the oxygen-enriched liquid mist flow 5 is the same as the rotation direction of the milling tool 9.

[0024] The specific process parameters for electrolytic milling of a plane using the electrolytic milling system of the present invention, which employs a combination of oxygen-enriched liquid mist and pulsed airflow, are as follows: grinding depth of 200 μm, spindle speed of 5000 rpm, feed rate of 15 mm / min, processing voltage of 12 V, and electrolyte flow rate of 2 L / h; the frequency of the pulse pressure of the airflow 4 is 100 Hz, the duty cycle is 0.5, and the pressure amplitude is 0.5 MPa; the oxygen volume ratio in the oxygen-enriched liquid mist 5 is 55%, the liquid is a 20 wt.% NaNO3 aqueous solution, and the microdroplet size is 10 ± 5 μm; the diameter of the grinding part of the milling tool 9 is 6 mm, the abrasive length is 10 mm, the binder is a nickel-cobalt alloy, the abrasive grains are diamond, and the grit size is 150#.

[0025] Figure 2 This is an electric field distribution diagram of a conventional electrolytic milling process. As can be seen from the diagram, a thick and continuous ordinary electrolyte film 26 exists in both the machining and non-machining areas. Numerous current lines 24 flow from the machined surface 16, the surface being machined 14, and the surface to be machined 22 of the workpiece 1 to the milling tool 9. Stray currents generated in the non-machining area, including the machined surface 16 and the surface to be machined 22, cause extensive stray corrosion on the machined surface during electrolytic milling, resulting in low machining accuracy. On the other hand, due to the use of a conventional oxygen-deficient electrolyte, the surface of the workpiece 1 in the machining area cannot quickly form an anodic film 12, failing to adapt to the predetermined mechanical film removal behavior. This results in severe grinding marks on the machined surface due to excessive grinding action, causing excessive wear on the milling tool 9.

[0026] Figure 3This diagram illustrates the principle of electrolytic milling of a plane using an oxygen-enriched liquid mist-pulsated airflow co-jet electrolytic milling system according to the present invention. As can be seen from the diagram, during the machining process, the special liquid supply method of high-speed jetting of oxygen-enriched liquid mist 5 ensures that only the electrolyte film 13 necessary for electrolytic machining forms between the machined surface 14 and the surface of the milling tool 9. The non-machined areas, including the machined surface 16 and the surface to be machined 22, do not experience liquid accumulation or flow. Under the impact of the airflow 4, which is periodically pulsed with pressure and sprayed onto the circumferential surface of the milling tool 9, a large amount of insoluble machining products 14 adhering to the surface of the milling tool 9 are rapidly removed, avoiding the short-circuit discharge phenomenon commonly found in conventional electrolytic milling, thus improving machining stability and efficiency.

[0027] Figure 4 This is an electric field distribution diagram of an electrolytic milling machined surface using an oxygen-enriched liquid mist-pulsated airflow co-spraying electrolytic milling system according to the present invention. As can be seen from the diagram, closed current lines 24 exist only in the machining area between the machined surface 14 and the milling tool 9, while no current lines exist in the non-machining areas, including the machined surface 16 and the surface to be machined 22, and the milling tool 9. Therefore, the electrochemical reaction only occurs in the machining area between the machined surface 14 and the milling tool 9, effectively suppressing stray current corrosion in the non-machining area, improving the machining localization of the electrolytic milling machined surface, and ensuring machining accuracy.

[0028] Figure 5 This is a schematic diagram of the reaction principle of the machining area of ​​the electrolytic milling and grinding system using an oxygen-enriched liquid mist-pulsated airflow spraying method. The system replaces the traditional conventional electrolyte with an oxygen-enriched mist electrolyte containing a high oxygen content (>50%). Under the combined action of oxygen 17 in the liquid mist and oxygen 23 generated during electrolysis, the anodic film 12 on the machined surface 14 of the workpiece 1 forms more quickly. This effectively avoids severe grinding marks on the machined surface and excessive wear on the milling tool 9 caused by excessive mechanical grinding of the workpiece 1 substrate by abrasive particles, effectively improving the surface quality and extending the service life of the milling tool 9.

Claims

1. An electrolytic milling system for co-spraying oxygen-enriched liquid mist and pulsating airflow, comprising a workpiece (1), a power supply (7), a milling tool (9), and a control switch (8), characterized in that: It also includes an integrated nozzle (3), an oxygen-enriched liquid mist (5), and an airflow (4); the integrated nozzle (3) is provided with an oxygen-enriched liquid mist nozzle (10) and an air nozzle (11) side by side; the oxygen-enriched liquid mist (5) is ejected from the oxygen-enriched liquid mist nozzle (10); the airflow (4) is ejected from the air nozzle (11) at high speed in a periodic pulse manner; the oxygen-enriched liquid mist (5) is sprayed toward the angle between the circumferential surface of the milling tool (9) and the machined surface (16); the airflow (4) is sprayed toward the circumferential surface of the milling tool (9); the oxygen volume ratio in the oxygen-enriched liquid mist (5) is greater than 50%; the ejection speed of the airflow (4) is greater than 10m / s, and the frequency and interval of the ejection are adjustable; the droplet size in the oxygen-enriched liquid mist (5) is 5-20μm; the oxygen-enriched liquid mist nozzle (10) and the air nozzle (11) are physically separated from each other.

2. The electrolytic milling system with oxygen-enriched liquid mist and pulsed airflow as described in claim 1, characterized in that: The liquid in the oxygen-enriched liquid mist (5) is an acidic or neutral electrolyte containing oxygen elements, and the mass percentage concentration of the electrolyte is 10-40 wt.%.

3. The electrolytic milling system with oxygen-enriched liquid mist and pulsed airflow as described in claim 1, characterized in that: The abrasive grains in the milling tool (9) are diamond or polycrystalline boron nitride with a particle size of 40-100μm, and the binder is a metal binder.

4. The electrolytic milling system with oxygen-enriched liquid mist and pulsed airflow as described in claim 1, characterized in that: The positive terminal of the power supply (7) is electrically connected to the workpiece (1) through the control switch (8), and the negative terminal is electrically connected to the milling tool (9).

5. The electrolytic milling system with oxygen-enriched liquid mist and pulsed airflow as described in claim 1, characterized in that: The distance between the integrated nozzle (3) and the milling tool (9) is adjustable.

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