Device and method for regulating stray current in closed member electrochemical machining

Abstract

The application discloses a closed component electrolytic machining stray current regulation device and method, and belongs to the technical field of electrolytic machining. The device comprises a liquid supply part and a stray current regulation part. The liquid supply part provides sufficient electrolyte for the closed component electrolytic machining. The stray current regulation part controls the stray current distribution through a gas isolation insulation method, and protects the formed blade. The application improves the machining precision and stability of the closed component electrolytic machining, and realizes high-quality and high-efficiency machining of the closed component.

Description

Technical Field

[0001] This invention relates to the field of electrolytic machining, and introduces a stray current control device for closed-loop component electrolytic machining. Background Technology

[0002] With technological advancements, the adoption of integral structures has simplified the structure of aero engines and significantly reduced the number of parts. However, this has also greatly increased the difficulty of machining. Integral closed components often use typical difficult-to-machine materials such as titanium alloys and nickel-based high-temperature alloys. Moreover, the closed structure of closed components, with its curved and narrow flow channel geometry, makes them difficult to reach with conventional machining tools. Closed components also require high stability in the machining process; if even one blade fails to meet standards, the entire component will be scrapped, resulting in high manufacturing risks and costs.

[0003] Electrochemical machining (ECM) is a manufacturing technology that removes materials using the electrochemical dissolution principle of metal anodes. Compared to traditional machining, ECM has become a key technology in the manufacturing of aerospace components due to its advantages such as high processing speed, good surface quality, no cutting force, and no tool cathode wear. However, during ECM, it is difficult to ensure that the electrolyte remains only in the machining area, resulting in secondary corrosion of the machined blades due to stray currents. A traditional solution is to apply an insulating coating to the back of the cathode; however, various surface insulating coatings are easily damaged and peeled off under the impact of high-speed, high-pressure electrolytes, resulting in weak adhesion to the substrate, short service life, and reduced ECM efficiency. For the high precision requirements of closed components, it is necessary to ensure the stability of the flow field during ECM and improve the consistency of machining accuracy.

[0004] The patent "A Method for Preparing an Insulating Coating for an Electrolytic Processing Cathode" (Application No. CN108607796A, Inventors: Zhang Zhijin, Zhang Mingqi, Chen Haiming, Huang Mingtao, Cheng Xiaoyuan) proposes using electrostatic spraying of phenolic resin powder for insulation. This method is relatively cumbersome and requires a high level of operator experience. The patent "A Method for Manufacturing a Cathode for Electrolytic Cutting" (Application No. CN107671504A, Inventors: Chen Zhitong, Yao Jun, Xu Zhipeng, Zhang Yanliang, Zhou Xiafang) proposes using high-strength fiber threads to sew the insulating layer together to improve bonding strength and durability. This method is suitable for hollow cathode structures and has certain limitations. The patent "A Device for Cathode Insulation in Electrolytic Processing" (Application No. CN108817582A, Inventors: Xu Kun, Zhang Chaoyang, Zhu Hao, Dai Xueren, Gu Qinming) proposes preparing a superhydrophobic microstructure on the cathode surface. This superhydrophobic structure adsorbs air bubbles, forming an insulating gas film to achieve selective insulation of the cathode surface. This method has a higher processing cost than traditional methods, and because it is essentially the same as insulating coatings, it is difficult to withstand the impact of high-speed, high-voltage electrolytes.

[0005] Existing electrochemical machining methods for closed-loop components lack durable and effective insulation protection for the machined blades, resulting in inconsistent precision and low machining efficiency, thus increasing the manufacturing risk of the overall closed-loop component. Therefore, there is an urgent need for an effective and easily implemented process to improve the precision and efficiency of electrochemical machining of closed-loop components and to provide durable protection for the formed blades, preventing secondary corrosion. Summary of the Invention

[0006] To achieve precision electrolytic machining of closed components and insulation protection for machined blades, this invention proposes a stray current control device for electrolytic machining of closed components. By regulating the gas flow rate, the electrolyte is controlled within the machining zone, and an automatically retractable water baffle prevents electrolyte leakage, thereby improving the stability of the electrolytic machining flow field and realizing precision electrolytic machining of closed blade rings and insulation protection for machined blades.

[0007] A stray current control device for electrolytic machining of closed-type components is used for precision electrolytic machining of closed-type blade profiles. It is characterized by comprising a left water-sealing fixture, a right water-sealing fixture, a left conductive block, a right conductive block, a left water-blocking block, a right water-blocking block, a blade basin cathode, and a blade back cathode. The left and right water-sealing fixtures are installed opposite each other, with a gap forming a liquid storage chamber. The left conductive block is embedded in the left water-sealing fixture, and the blade basin cathode is installed inside the left water-sealing fixture and connected to the left conductive block. The right conductive block is embedded in the right water-sealing fixture, and the blade back cathode is installed inside the right water-sealing fixture and connected to the right conductive block. The machining surface of the blade basin cathode is designed according to the blade basin design, with its two end faces designed according to the inner and outer flow channels, respectively. The machining surface of the blade back cathode is designed according to the blade back design, with its two end faces designed according to the inner and outer flow channels, respectively. The blade basin cathode and blade back cathode are inserted into the machining area of ​​the closed-type component. The blade basin cathode is further... The area between the working surface and the blade basin profile to be processed is called the blade basin processing area, and the area between the back of the blade basin cathode and the blade back profile of the processed blade is called the blade back protection area; the area between the blade back cathode processing surface and the blade back profile to be processed is called the blade back processing area, and the area between the back of the blade back cathode and the blade basin profile of the processed blade is called the blade basin protection area; one end of the liquid storage chamber between the left and right sealing clamps is the liquid inlet, and the other end is the liquid outlet, which is connected to the blade basin processing area and the blade back processing area; an air passage is opened on the back side of the blade basin cathode, and the air passage inlet is connected to the air source equipment through the air passage provided on the left conductive block and the air passage provided on the left sealing clamp in sequence; the air passage outlet is provided with a flow regulating hole and is connected to the blade back protection area; an air passage is opened on the back side of the blade back cathode, and the air passage inlet is connected to the air source equipment through the air passage provided on the right conductive block and the air passage provided on the right sealing clamp in sequence; the air passage outlet is provided with a flow regulating hole and is connected to the blade basin protection area. The aforementioned left water-sealing clamp is equipped with a left water-blocking block, which is located on the left side of the blade back protection area of ​​the closed component blank; the right water-sealing clamp is equipped with a right water-blocking block, which is located on the right side of the blade basin protection area of ​​the blade ring blank; the left and right water-blocking blocks are tightly fitted to the upper end face of the closed component blank under the action of the telescopic spring to prevent electrolyte and high-pressure gas from leaking from the gap between these end faces.

[0008] The aforementioned stray current control device for closed-type component electrolytic machining is characterized in that: the number and size of the flow regulating holes located at the air outlets on the back of the blade cathode and the blade back cathode are designed according to the stray current density in the non-machined area during machining. The gas flow rate is controlled by simulating the gas pressure and the size of the holes through simulation software, thereby controlling the stray current and preventing corrosion of the non-machined area.

[0009] The method for controlling stray current in closed-type component electrolytic machining is characterized by the following steps: Before machining, the blade basin cathode, blade back cathode, left conductive block, right conductive block, telescopic spring, left water-blocking block, and right water-blocking block are all installed in the water-sealing fixture module, and the entire fixture module is connected to the machine tool drive shaft; the fixture module is adjusted to achieve fixture mold closing, and the fixture is moved to the initial machining position; the closed-type component blank is installed; during machining, the electrolyte flows in from the inlet, passes through the liquid storage chamber of the fixture module, and flows out from the blade basin machining area and the blade back machining area; high-pressure gas flows out from... Air flows in through the inlet, and the blade head cathode and blade back cathode are fed towards the blade profile. Under the action of the flow regulating hole, high-pressure gas enters the blade back protection zone and blade head protection zone to form a gas shield layer, which prevents excess electrolyte from entering the non-processing area from the inner and outer channels of the closed component. This regulates the distribution of stray current and avoids secondary corrosion of the processed blade. After processing, the blade is retracted, the electrolyte valve and gas valve are closed, and the cathode is withdrawn from the channel of the closed component. The index is rotated to move the cathode into the next blade channel, ready to start processing the next blade.

[0010] The advantages of this invention are:

[0011] This invention avoids secondary corrosion of machined blades in closed-type components, effectively improving the precision of electrochemical machining of closed-type components. A stray current control device for electrochemical machining of closed-type components is proposed, which regulates the distribution of stray current by controlling the flow rates of electrolyte and gas, thus preventing secondary corrosion of machined blades.

[0012] This invention improves the stability of electrolytic machining of closed components. The telescopic water-blocking block prevents electrolyte and gas leakage from the gap between the fixture and the closed component blank, ensuring an adequate supply of electrolyte and gas to the machining area.

[0013] This invention improves the consistency and efficiency of electrolytic machining allowances for closed components. A stable gas supply ensures continuous insulation, avoiding repeated cathode insulation and secondary clamping. This process is highly adaptable and can process closed components or other integral components of various specifications. Attached Figure Description

[0014] Figure 1 Schematic diagram of closed-type component electrolytic machining fixture and cathode insulation

[0015] Figure 2 Schematic diagram of closed component processing area

[0016] Figure 3 Schematic diagram of water-retaining block structure

[0017] The labels in the diagram are as follows: 1. Liquid inlet, 2. Air inlet, 3. Left water seal clamp, 4. Right water seal clamp, 5. Left conductive block, 6. Right conductive block, 7. Telescopic spring, 8. Left water baffle, 9. Right water baffle, 10. Closed component blank, 11. Flow adjustment hole, 12. Blade back protection area, 13. Blade basin protection area, 14. Blade basin cathode, 15. Blade back cathode, 16. Blade basin machining area, 17. Blade back machining area, 18. Liquid storage chamber, 19. Closed component internal flow channel, 20. Closed component external flow channel. Specific implementation methods

[0018] The following is in conjunction with the appendix Figure 1 , Figure 2 The specific implementation process of the present invention is described in detail below:

[0019] The process of electrolytic machining of workpieces using the "A Closed-Type Component Electrolytic Machining Stray Current Control Device" of the present invention includes the following steps:

[0020] Step 1: Insert the left and right conductive blocks into the back of the water sealing fixture and connect and fix them to the water sealing fixture. Connect and fix the blade basin cathode and blade back cathode to the left and right conductive blocks respectively. Then, install the fixture module as a whole onto the machine tool drive shaft.

[0021] Step 2: Adjust the position of the water-sealing fixture module to complete the mold closing and tool setting of the water-sealing fixture module. After moving the water-sealing fixture module to the initial processing position, install the telescopic spring and the left and right water-blocking blocks to the bottom of the water-sealing fixture module.

[0022] Step 3: Install the closed component blank onto the workbench, then move it under the water-sealing clamp module and press it against the water-blocking block;

[0023] Step 4: Turn on the air source and adjust the air pressure. Blow the air through the air pressure pipe towards the processed blades in the non-processed area on the back of the cathode. Turn on the electrolyte circulation system, introduce electrolyte, and adjust the electrolyte pressure.

[0024] Step 5: Turn on the power, start the machine tool program to begin machining. After the blade head cathode and blade back cathode are fed into place, the cathodes are withdrawn. Rotate the worktable to machine the next blade.

[0025] Step 6: After processing all blades, turn off the power, electrolyte circulation system and gas source, return the cathode to the initial position, remove the workpiece and water sealing fixture module, and clean the machine tool.

Claims

1. A stray current control device for electrolytic machining of closed components, used for precision electrolytic machining of closed blade ring-type blade profiles, characterized in that: It includes a left water sealing clamp (3), a right water sealing clamp (4), a left conductive block (5), a right conductive block (6), a left water blocking block (8), a right water blocking block (9), a leaf basin cathode (14), and a leaf back cathode (15); the left water sealing clamp (3) and the right water sealing clamp (4) are installed opposite each other, and the gap in the middle forms a liquid storage chamber (18); The left conductive block (5) is embedded in the left water sealing clamp (3), and the leaf basin cathode (14) is installed inside the left water sealing clamp (3) and connected to the left conductive block (5); the right conductive block (6) is embedded in the right water sealing clamp (4), and the leaf back cathode (15) is installed inside the right water sealing clamp (4) and connected to the right conductive block (6). The machining surface of the blade basin cathode (14) is based on the blade basin design, and the two end faces are designed according to the inner flow channel surface and the outer flow channel surface, respectively; the machining surface of the blade back cathode (15) is based on the blade back design, and the two end faces are designed according to the inner flow channel surface and the outer flow channel surface, respectively. The blade base cathode (14) and the blade back cathode (15) are inserted into the processing area of ​​the closed component; the area between the processing surface of the blade base cathode (14) and the blade base profile to be processed is called the blade base processing area (16), and the area between the back of the blade base cathode (14) and the blade back profile of the processed blade is called the blade back protection area (12); the area between the processing surface of the blade back cathode (15) and the blade back profile to be processed is called the blade back processing area (17), and the area between the back of the blade back cathode (15) and the blade base profile of the processed blade is called the blade base protection area (13). One end of the liquid storage chamber (18) between the left water sealing clamp (3) and the right water sealing clamp (4) is the liquid inlet (1), and the other end is the liquid outlet. The liquid outlet is connected to the leaf basin processing area (16) and the leaf back processing area (17). The back side of the leaf basin cathode (14) has an air channel. The air channel inlet is connected to the air source equipment through the air channel set on the left conductive block (5) and the air channel set on the left sealing water clamp (3) in sequence. The air channel outlet is provided with a flow regulating hole (11) and is connected to the leaf back protection area (12). The back of the leaf cathode (15) has an air passage. The air passage inlet is connected to the air source equipment through the air passage set on the right conductive block (6) and the air passage set on the right sealing clamp (4). The air passage outlet is provided with a flow regulating hole (11) and is connected to the leaf basin protection area (13). The left water sealing clamp (3) is provided with a left water blocking block (8), which is located on the left side of the blade back protection area of ​​the closed component blank; the right water sealing clamp (4) is provided with a right water blocking block (9), which is located on the right side of the blade basin protection area of ​​the blade ring blank; the left water blocking block (8) and the right water blocking block (9) are tightly fitted to the upper end face of the closed component blank under the action of the telescopic spring (7) to prevent electrolyte and high pressure gas from leaking from the gap of this end face.

2. The stray current control device for closed-loop component electrolytic machining according to claim 1, characterized in that: The flow regulating holes (11) located at the air outlets on the back of the leaf basin cathode (14) and the leaf back cathode (15) are designed based on the stray current density in the non-processed area during processing. The gas flow rate is controlled by simulating the air pressure and the size of the holes through simulation software, thereby controlling the stray current and preventing corrosion of the non-processed area.

3. The method for controlling stray current in closed-loop component electrolytic machining according to claim 1, characterized in that... Includes the following processes: Before processing, install the blade basin cathode (14), blade back cathode (15), left conductive block (5), right conductive block (6), telescopic spring (7), left water baffle (8) and right water baffle (9) in the sealing fixture module, and connect the entire fixture module to the machine tool drive shaft; adjust the fixture module to realize the clamping of the fixture, move the fixture to the initial processing position; install the closed component blank; During processing, the electrolyte flows in from the inlet (1), passes through the liquid storage chamber (18) of the fixture module, and flows out from the blade basin processing area (16) and the blade back processing area (17). High-pressure gas flows in from the inlet (2), and the blade basin cathode (14) and the blade back cathode (15) are fed towards the blade profile direction respectively. Under the action of the flow regulating hole, the high-pressure gas enters the blade back protection area (12) and the blade basin protection area (13) to form a gas shield layer, which blocks excess electrolyte from entering the non-processing area from the inner flow channel (19) and outer flow channel (20) of the closed component, and regulates the distribution of stray current to avoid secondary corrosion of the processed blade. After machining is completed, the tool is retracted, the electrolyte valve and gas valve are closed, the cathode is removed from the channel of the closed component, the index is rotated, and the cathode is moved into the channel of the next blade to prepare for machining the next blade.

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