Tubular combined cathode tool and rotating cathode electrolytic milling method thereof

Abstract

The invention relates to a tubular combined cathode tool and a rotating cathode electrolytic milling method thereof, and belongs to the field of electrolytic machining. The combined cathode tool comprises a tubular cathode, an inner insulating shell, a sealing rubber ring and an outer insulating shell. And the inner insulating shell, the sealing rubber ring and the outer insulating shell are concentrically nested on the outer circle of the tubular cathode in sequence. And an electric field and a flow field are perfectly restrained by rigid, flexible and rigid three-layer insulation sealing. The electrolyte carrying the processing product cannot overflow from the processing gap and is discharged from the lateral liquid outlet in a large-flow manner, so that the residual product is prevented from adhering to the processed surface, the high conductivity of the electrolyte in the processing gap is ensured, and the quality of the processed surface and the material removal rate are remarkably improved. And the electric field is limited by three layers of insulation and cannot diffuse outwards, and the electric quantity is intensively supplied to a projection area under the tubular cathode, so that the machining current density is improved, and the machining locality, the machining precision and the machining efficiency of rotating cathode electrolytic milling are remarkably improved.

Description

Technical Field

[0001] The present invention relates to a tubular combined cathode tool and a rotary cathode electrochemical milling method, belonging to the field of electrochemical machining. Technical Background

[0002] Rotary cathode electrochemical milling is a special machining technology based on the principle of anodic dissolution in electrochemistry. During the working process, a rotating rod-shaped electrode is generally used as the cathode, and the workpiece is used as the anode. The two are connected by an electrolyte jet. When a voltage is applied between the two electrodes, metal atoms on the surface of the anode workpiece lose electrons and become metal ions dissolved in the electrolyte, achieving the purpose of removing the anode material. During this process, the electrolyte continuously circulates and flows, taking away the dissolved metal ions and reaction products to ensure the continuous progress of the machining. Compared with traditional mechanical milling, there is no mechanical cutting force during the rotary cathode electrochemical milling process, which avoids problems such as workpiece deformation and residual stress caused by cutting force, and is suitable for machining thin-walled and easily deformable parts; at the same time, electrochemical machining does not have the problem of tool wear, which can not only reduce the tool cost, but also ensure the stability and consistency of the machining process.

[0003] During the rotary cathode electrochemical milling process, the flow field can affect the transport of ions in the electrolyte, enabling the metal ions generated by anodic dissolution to quickly leave the machining area and preventing the accumulation of metal ions near the electrode. This not only prevents the occurrence of concentration polarization phenomena in the machining gap and maintains a stable machining electric field, but also effectively reduces the adhesion of machining products on the workpiece surface, thereby improving the machining accuracy and surface quality. The electric field strength and its distribution directly determine the anodic dissolution rate and dissolution path of the metal on the workpiece surface. By precisely controlling the electric field parameters, such as voltage and current density, fine control of the machining accuracy and surface quality can be achieved. The non-uniformity of the electric field distribution will cause inconsistent dissolution rates at different parts of the workpiece surface, resulting in an increase in the surface roughness of the machining surface and an increase in the shape error. Therefore, the design of the flow field and the electric field is crucial for achieving precise and efficient machining of rotary cathode electrochemical milling.

[0004] During the general rotary cathode electrochemical milling process, the electrolyte sprays out from the gap between the anode and the cathode. The horizontally narrowing interelectrode gap will cause hydraulic mutations and flow field disorders, resulting in some products remaining adhered to the machined surface and the area to be machined, which will damage the surface quality of the machining. To address such problems, common improvement methods include ultrasonic assistance, vibrating electrode method, and air pressure control method, etc. The patent "Ultrasonic-assisted Rotary Tube Electrochemical Machining Device Machine Tool and Method" (Publication No.: CN113828876A) invented an ultrasonic-assisted rotary tube electrochemical machining device, which uses an ultrasonic component to vibrate the tool electrode, prompting the electrolyte in the gap between the anode and the cathode to vibrate continuously, thereby improving the uniformity of electrolyte distribution and avoiding problems such as cavitation or poor electrolyte flow. The patent "HIFU-assisted Electrochemical Machining Device and Method" (Publication No.: CN118768662A) effectively changes the position of the ultrasonic focus through the up and down vibration of the focused ultrasonic transducer, thereby generating a more chaotic sound pressure field and improving the electrolyte renewal efficiency. These ultrasonic-assisted methods are simple to operate and have obvious effects, but they require external ultrasonic-assisted equipment, which is relatively complex to install and has a relatively high cost. The vibrating electrode method is similar in principle to the ultrasonic assistance method, and realizes the periodic change of the machining gap between the anode and the cathode by controlling the periodic vibration of the cathode. In this way, electrolytic machining is carried out when the power is turned on at the minimum machining gap, and when the cathode vibrates away from the minimum gap, the power supply is turned off and the electrolytic machining stops. A negative pressure is formed when the gap reaches the maximum (vibrating to the uppermost end), which promotes the rapid renewal of the electrolyte. The patent "A Cathode Vibration Device for Electrochemical Machining" (Publication No.: CN109570661A) uses a cathode vibration device to achieve periodic vibration motion. The vibrating electrode method has significant effects, but it also requires an external device and has a high cost. In addition, for the vibrating electrode method, basically a pulse power supply needs to be configured, and it is difficult to synchronize the electrode vibration period and the power supply pulse period.

[0005] Another method for improving the electrolyte flow field is the air pressure control method, which affects the flow field by controlling the gas pressure near the cathode, thereby accelerating the renewal of the electrolyte. The patent "Electrolytic milling machining device with controllable electrolyte orientation and its machining process" (Publication No.: CN113210771A) controls the flow direction of the electrolyte in a targeted manner by fixing a nozzle array capable of ejecting high-pressure gas around the tool electrode, so that the gap in the machining area obtains sufficient electrolyte and discharges the electrolysis products. The patent "Vane-combined rotary cathode electrolytic milling tool and method" (Publication No.: CN113458515A) sets an impeller on the tool electrode, and the upward gas flow field generated by the rotation of the tool electrode drives the impeller to provide a low-pressure area far lower than the atmospheric pressure for the electrolyte in the machining gap, accelerating the flow and renewal of the electrolyte. The principle of the air pressure control method is simple and the effect is remarkable. However, in order to achieve the expected effect, it is necessary to externally connect a gas supply device to provide air pressure higher than the water pressure or drive the impeller to rotate at a high enough speed to affect the flow field. These all pose higher requirements for the machining equipment and there will also be certain safety hazards.

[0006] In terms of electric field optimization, the exposed outer wall of the cathode in electrolytic milling machining will produce an edge diffusion effect, generating a low current density area on the anode surface, secondary-corroding the machined surface, and causing stray corrosion on the side walls of the groove contour, damaging the machining localization and machining accuracy. Some scholars have eliminated this adverse effect of the electric field by making corresponding pre-treatments on the workpiece surface. The patent "Internal liquid spraying rotary cathode mask electrolytic machining method and implementation device" (Publication No.: CN113878185A) eliminates the electric field edge effect by making a reciprocating linear motion along the radial direction of the rotating workpiece with a cathode having phyllotaxis-distributed liquid through holes, and the workpiece has been pre-treated with a hollow insulation structure. Although the machining effect becomes controllable, the pre-treatment of the workpiece greatly reduces the adaptability of this method. The auxiliary anode method can also improve the electric field edge effect and stray corrosion in electrolytic machining. In the patent "Special-shaped hole electrolytic machining device and method for actively suppressing stray corrosion" (Publication No.: CN107999907A), a low-voltage controllable electric field is externally set up to comb the stray electric field to suppress the generation of stray corrosion. This method has a general effect and cannot be eradicated, and the external device is too complex, greatly increasing the machining cost. Therefore, it is necessary to find a simple device to improve the flow field and electric field, and improve the machining quality and machining accuracy of rotary cathode electrolytic milling. Summary of the Invention

[0007] In view of the problems existing in the above-mentioned prior art, the present invention designs a tubular combined cathode tool and its rotary cathode electrochemical milling method, aiming to simultaneously realize the constraint of the electric field and the flow field with a simple device, change the traditional discharge mode of the electrolyte overflowing from the machining gap to the surroundings, ensure the high cleanliness and high conductivity of the electrolyte in the machining gap, and at the same time concentrate the electric quantity in the projection area directly below the cathode, improve the machining current density, and enhance the machining efficiency and machining surface quality of the electrochemical milling process.

[0008] A tubular combined cathode tool is composed of an inner and an outer layer. The inner layer is a tubular cathode, and the outer layer is an insulating and sealing shell. It is characterized in that: the lower end of the insulating and sealing shell extends beyond the tubular cathode, and the extended part is flexible, and the extended part is used to supplement the seal of the depression after the removal of the machined surface material; a plurality of lateral liquid discharge ports are arranged along the circumferential direction of the lower end pipe wall of the above-mentioned tubular cathode, and a side discharge hole structure corresponding to the position and shape of the lateral liquid discharge ports is provided on the insulating and sealing shell.

[0009] The above-mentioned tubular combined cathode tool is characterized in that: the lateral liquid discharge ports of the above-mentioned tubular cathode are polygonal or circular.

[0010] The above-mentioned tubular combined cathode tool is characterized in that: the bottommost end of the lateral liquid discharge ports of the above-mentioned tubular cathode is located above the bottom surface of the tubular cathode, and the height from its bottom surface is 2 to 5 times the thinnest wall thickness value of the tubular cathode.

[0011] The above-mentioned tubular combined cathode tool is characterized in that: the interior of the above-mentioned tubular cathode is divided into several axial unit flow channels by partitions, and each axial unit flow channel corresponds to and communicates with a lateral liquid discharge port.

[0012] During the rotary cathode electrochemical milling process, the electrolyte is input from the top end of the rotary cathode and vertically ejected from the bottom end. After filling the gap between the anode and the cathode, that is, the machining gap, it overflows to the surroundings. Generally speaking, the machining gap in electrochemical milling does not exceed 1 mm, which is much smaller than the area of the ejection port at the bottom end of the rotary cathode. Therefore, after the electrolyte participates in the electrolysis process, it will be hindered from being discharged by the small machining gap, and some of the electrolysis products it carries will remain in the machining gap, reducing the conductivity of the electrolyte in the machining gap and weakening the machining efficiency. In addition, after the electrolyte is discharged from the machining gap, it will inevitably sweep across the machined surface, which will cause some of the discharged products to adhere to the machined surface, damaging the surface quality of the machining. Therefore, the purpose of the present invention is to completely change this mode of electrolyte discharge that overflows to the surroundings from the machining gap. The tubular combined cathode tool designed in the present invention uses an insulating seal to block the outlet of the machining gap to the outside. Therefore, the lower end of the insulating seal should extend beyond the tubular cathode, and the extended length should not be less than the height of the machining gap. However, the composite dynamic machining mode of the rotary cathode rotating and feeding while and the complex topography of the workpiece surface after machining have greatly increased the difficulty of fully blocking the insulating seal, and a flexible structure is needed to overcome it. After the insulating seal completely blocks the outlet of the machining gap to the outside, the electrolyte can only be discharged outward through the lateral drainage ports on the lower end wall of the tubular cathode. Therefore, a side drainage hole structure corresponding to the position and shape of the lateral drainage ports needs to be provided on the insulating seal to avoid interfering with and hindering the discharge of the electrolyte. Considering the lateral discharge flow field, the height of the bottom end of the lateral drainage port of the tubular cathode from its bottom surface should be 2 to 5 times the thickness of the thinnest wall of the tubular cathode. If the height is too low, it may cause problems such as unstable structure at the lower end of the tubular cathode, difficult manufacturing of the lateral drainage port, and insufficient lateral discharge distance of the electrolyte. If the height is too high, it will cause unsmooth lateral discharge of the electrolyte. Similarly, in order to maintain an orderly and stable flow field, each axial unit flow channel inside the tubular cathode corresponds to and communicates with a lateral drainage port, and this one-to-one correspondence avoids mutual interference between different flow channels.

[0013] The above-mentioned tubular combined cathode tool is characterized in that: The above-mentioned insulating seal includes an inner insulating shell, a sealing rubber ring and an outer insulating shell; The above-mentioned tubular cathode is a circular tube electrode, which is divided into upper and lower cylindrical structures. The outer diameter of the upper cylindrical structure is larger than the outer diameter of the lower cylindrical structure; The above-mentioned inner insulating shell is a tubular structure, and its inner diameter is equal to the outer diameter of the lower cylindrical structure of the tubular cathode; the outer circle of the inner insulating shell is divided into an upper outer circle part and a lower outer circle part, and the diameter of the upper outer circle part is larger than the diameter of the lower outer circle part; two rectangular tool setting bosses extending downward are uniformly arranged along the circumferential direction on the upper outer circle part of the inner insulating shell; a radial boss is provided on the lower outer circle part of it directly below the rectangular tool setting bosses, and the radial boss is provided with side drainage holes of the inner insulating shell; The outer insulating shell is composed of a pair of semi-circular tube shells, and the inner wall of the outer insulating shell is composed of an upper inner wall, a middle inner wall, and a lower inner wall; wherein the inner diameter of the upper inner wall is equal to the outer diameter of the upper outer circular part of the inner insulating shell, the inner diameter of the middle inner wall is equal to the outer diameter of the lower outer circular part of the inner insulating shell, and the inner diameter of the lower inner wall is equal to the outer diameter of the radial boss on the lower outer circular part of the inner insulating shell; the middle inner wall of the outer insulating shell is provided with a tool setting groove matching the rectangular tool setting boss at the joint of the semi-circular tube shells; the lower inner wall of the outer insulating shell is provided with a row of holes on the side of the outer insulating shell; The sealing rubber ring is a flexible circular tube structure, the inner diameter of which is interference fit with the outer diameter of the outer circular part of the inner insulating shell, and the outer diameter of which is interference fit with the inner diameter of the inner wall of the outer insulating shell; the length of the sealing rubber ring exceeds the height of the inner wall of the outer insulating shell, and the excess part is used to supplement the sealing of the depression after the processed surface material is removed; the sealing rubber ring is provided with side holes of the sealing rubber ring; The lateral liquid discharge port, the inner insulating shell side discharge holes, the sealing rubber ring side discharge holes, and the outer insulating shell side discharge holes of the tubular electrode correspond to each other in position and have matching structures and shapes; The inner insulating shell is sleeved on the cylindrical structure of the lower part of the tubular cathode from bottom to top, and the top surface of the inner insulating shell is in contact with the step surface dividing the upper and lower parts of the tubular cathode and is coplanar; the upper outer circular part of the inner insulating shell is arranged with a plurality of radial threaded through holes along the circumference, and the outer circular surface of the cylindrical structure of the lower part of the tubular cathode is pressed against by a set screw in the radial threaded through hole to complete the fixation of the two; the rectangular tool setting boss of the inner insulating shell is also provided with a radial threaded blind hole; The sealing rubber ring is nested on the lower outer circumference of the inner insulating shell from bottom to top, and its side holes are sleeved on the radial boss of the lower outer circumference of the inner insulating shell; The two semicircular tube shells of the above-mentioned outer insulating shell are radially aligned and assembled to wrap the inner insulating shell and the sealing rubber ring, so that the upper surface of the middle inner wall of the outer insulating shell is against the bottom surface of the rectangular tool-aligning boss extending from the upper outer circular part of the inner insulating shell, and at the same time, the lower surface of the middle inner wall of the outer insulating shell presses the top surface of the sealing rubber ring, so that the entire outer circular surface of the sealing rubber ring is in contact with the lower inner wall of the outer insulating shell; a central through hole is also opened in the center of the upper inner wall of the semicircular tube shell of the above-mentioned outer insulating shell, and the outer insulating shell is connected and positioned in the central through hole with a radial threaded blind hole arranged on the rectangular tool-aligning boss of the inner insulating shell by a positioning screw.

[0014] The above-mentioned tubular combined cathode tool is characterized in that: The total height of the inner insulating shell is equal to the sum of the height of the cylindrical structure of the lower part of the tubular cathode and the height of the initial machining gap of the electrolytic milling; the distance from the bottom surface of the rectangular tool boss extending from the outer circular part of the inner insulating shell to the bottom surface of the inner insulating shell is equal to the sum of the heights of the inner wall and the lower inner wall of the outer insulating shell.

[0015] The inner insulating shell is the innermost part of the insulating sealing shell. It is directly sleeved on the outer circle of the tubular cathode to play a role. Therefore, the inner diameter of the inner insulating shell is equal to the outer diameter of the cylindrical structure of the lower part of the tubular cathode, so as to radially position it. In the axial direction, the interface between the upper and lower cylindrical structures of the tubular cathode becomes the positioning surface of the inner insulating shell. In the circumferential direction, the lateral drainage port of the tubular electrode and the side drainage hole of the inner insulating shell correspond to each other in position, and the structural shapes match. After positioning, the inner insulating shell and the tubular cathode are fixed together using the set screws in the radial threaded through hole. As the first barrier to plugging, the inner insulating shell must have sufficient rigidity to resist the fluid, so the plugging depth it can reach (the depth beyond the bottom surface of the cathode) is the initial machining gap height before electrolytic milling begins. Therefore, the total height of the inner insulating shell is equal to the sum of the height of the cylindrical structure of the lower part of the tubular cathode and the initial machining gap height of electrolytic milling. In this way, the position of the tubular cathode can be indirectly determined by facing the bottom of the inner insulating shell. When the workpiece surface is processed, a complex uneven morphology will appear. The newly added depression exceeds the sealing depth of the inner insulating shell, and a flexible sealing rubber ring is required to be placed on the bottom of the inner insulating shell as a second barrier to supplement the sealing. In order to ensure that the sealing rubber ring is always sealed downward instead of deforming toward the periphery during the process of rotating and feeding with the cathode, it is necessary to put on another layer of rigid outer insulating shell and the inner insulating shell to clamp the sealing rubber ring together, and the outer insulating shell and the inner insulating shell must be closely matched to restrain the upward reaction force of the sealing rubber ring. Therefore, the inner insulating shell adopts a stepped shape with a diameter of the upper outer circle part larger than the diameter of the lower outer circle part, and the outer insulating shell is a whole circle of raised middle inner wall with the smallest inner diameter. The upper surface of the middle inner wall of the outer insulating shell is used to resist the bottom surface of the rectangular tool boss extending from the upper outer circle part of the inner insulating shell, and at the same time, the lower surface of the middle inner wall presses the top surface of the sealing rubber ring. In addition, in order to ensure a tight fit between the two, the inner diameter of the upper inner wall of the outer insulating shell is equal to the outer diameter of the upper outer circular part of the inner insulating shell, the inner diameter of the middle inner wall is equal to the outer diameter of the lower outer circular part of the inner insulating shell, the inner diameter of the lower inner wall is equal to the outer diameter of the radial boss on the lower outer circular part of the inner insulating shell, and the distance from the bottom surface of the rectangular tool boss extending from the upper outer circular part of the inner insulating shell to the bottom surface of the inner insulating shell is equal to the sum of the heights of the middle inner wall and the lower inner wall of the outer insulating shell. In this way, only the lower inner wall and the lower outer circular part of the inner insulating shell have gaps in the entire outer insulating shell, which becomes the installation space for the entire sealing rubber ring. In addition, it is also necessary to ensure that the inner diameter of the sealing rubber ring has an interference fit with the outer diameter of the lower outer circular part of the inner insulating shell, and its outer diameter must have an interference fit with the inner diameter of the lower inner wall of the outer insulating shell, and its length must exceed the height of the lower inner wall of the outer insulating shell, so that the sealing rubber ring can be squeezed all the time, so that it accumulates sufficient elastic potential energy and can timely seal the depression of the processed surface. After radial and axial extrusion, the sealing rubber ring and the inner insulating shell still need circumferential constraints, so a radial boss is set on the outer circle of the lower inner insulating shell for the side holes of the sealing rubber ring to fit on. After the sealing rubber ring is fixed, the circumferential positioning of the outer insulating shell remains. The outer insulating shell is tightened and positioned by inserting a positioning screw in the center through hole and screwing it into the radial threaded blind hole set on the rectangular tool boss of the inner insulating shell.At this time, the side discharge holes on the inner insulating shell located on the radial boss directly below the rectangular tool setting boss correspond exactly to the side discharge holes on the outer insulating shell directly below the central through hole. Finally, since the bottom surface of the inner insulating shell is needed for tool setting, for convenience, a rectangular tool setting boss is provided on the inner insulating shell and a tool setting groove is provided on the outer insulating shell. The cooperation of the two can lift the sealing rubber ring and the outer insulating shell without removing the overall combined cathode tool, exposing the bottom surface of the inner insulating shell.

[0016] The above-mentioned tubular combined cathode tool is characterized in that: the tubular cathode is made of metal material, the inner insulating shell and the outer insulating shell are made of rigid insulating material, and the sealing rubber ring is made of latex or silica gel insulating material.

[0017] The above-mentioned tubular combined cathode tool is characterized in that: the rigid insulating material is polyether ether ketone (PEEK), polyoxymethylene (POM).

[0018] The rotary cathode electrochemical milling method using the above-mentioned tubular combined cathode tool is characterized by including the following processes: Step 1: Tool setting: The tubular cathode is connected to the negative pole of the power supply and vertically clamped on the machine tool spindle, and the workpiece is connected to the positive pole of the power supply; Remove the positioning screw, rotate the outer insulating shell relative to the inner insulating shell so that the two rectangular tool setting bosses on the inner insulating shell are respectively directly above the tool setting grooves at the joint of the inner walls of the outer insulating shell; Then push the outer insulating shell upward until each tool setting groove of the outer insulating shell contacts and cooperates with the rectangular tool setting boss of the inner insulating shell. At the same time, lift the exposed sealing rubber ring upward and outward to support the outer insulating shell and expose the bottom of the inner insulating shell; Move the machine tool spindle for tool setting until the bottom surface of the inner insulating shell just touches the upper surface of the workpiece, and the tool setting is completed; Then put down the lifted sealing rubber ring to wrap the bottom of the inner insulating shell again, and press the outer insulating shell so that the upper surface of the inner wall of each semi-cylindrical shell of the outer insulating shell drops to be coplanar with the bottom surface of the rectangular tool setting boss of the inner insulating shell; Rotate the outer insulating shell relative to the inner insulating shell again so that the central through hole on the upper inner wall of the outer insulating shell aligns with the radial threaded blind hole provided on the rectangular tool setting boss of the inner insulating shell; Finally, insert the positioning screw and tighten it to fix the relative position of the inner insulating shell and the outer insulating shell. The upper surface of the inner wall of the outer insulating shell abuts against the bottom surface of the rectangular tool setting boss extending from the outer circle part of the upper part of the inner insulating shell, and the lower surface of the inner wall of the outer insulating shell presses the top surface of the sealing rubber ring to ensure that the space between the lower outer circle part of the inner insulating shell and the lower inner wall of the outer insulating shell is filled and sealed. At the same time, the side discharge holes on the lower inner wall of the outer insulating shell also align with the side discharge holes on the radial boss of the inner insulating shell. Thus, the assembly and positioning of the tubular combined cathode tool in the machining state are completed; Step 2. Processing: Input the electrolyte, allowing the electrolyte to flow through the tubular cathode via the spindle to the machining area of the workpiece, and energize the tubular cathode and the workpiece; the workpiece material directly below the tubular cathode dissolves under the action of electrolysis and generates a large number of insoluble electrolysis product particles; due to the rigid + flexible + rigid three-layer insulation and sealing provided by the inner insulation shell, the sealing rubber ring, and the outer insulation shell, the electrolyte is prevented from diffusing outward through the machining gap, and the electrolyte carrying the machining products can only be discharged in large quantities from the lateral drainage port of the tubular cathode, ensuring high cleanliness and high conductivity of the electrolyte within the machining gap, significantly improving the machining surface quality and material removal rate; while the electric field is restricted by the three-layer insulation and cannot diffuse outward, and the electric quantity is concentrated in the projection area directly below the tubular cathode, enhancing the machining current density and significantly improving the machining accuracy and localization; the three-layer insulation and sealing structure simultaneously restricts the electric field and the flow field, not only avoiding the adhesion and contamination of the electrolysis products to the machined surface but also suppressing the edge diffusion effect of the electric field, eliminating secondary damage to the machined surface, preventing the generation of stray corrosion, and significantly improving the machining surface quality.

[0019] The present invention has the following advantages: 1. The combined tool of the present invention has a simple structure and low cost. Without additional complex devices and control programs, the electric field and the flow field can be perfectly restricted only by the rigid + flexible + rigid three-layer insulation and sealing structure. The flexible sealing rubber ring extruded between the inner and outer insulation shells always accumulates sufficient elastic potential energy, which can timely seal the depressions on the machined surface and can better cope with various uneven workpiece surface topographies, significantly enhancing the adaptability of the present invention. Moreover, the present invention has no size limitation, and the elasticity of the flexible sealing rubber ring can also be replaced and adjusted, with a wide range of applications.

[0020] 2. The process method of the present invention is convenient and efficient, and controls both the electric field and the flow field. On the one hand, it guides the electrolyte carrying the machining products to be discharged in large quantities from the lateral drainage port at the bottom of the tubular cathode, preventing it from overflowing from the machining gap and avoiding the adhesion of the products to the machined surface, effectively ensuring high cleanliness and high conductivity of the electrolyte within the machining gap; on the other hand, it concentrates the electric field in the projection area directly below the tubular cathode, enhancing the machining current density, avoiding stray corrosion, and simultaneously achieving significant improvement in machining accuracy, machining localization, machining efficiency, and machining surface quality.

[0021] 3. The structure of the present invention is ingeniously designed. Without repeated disassembly and assembly, it can be flexibly switched between the tool setting state and the machining state only by simple rotation and positioning, which is convenient for tool setting, time-saving and labor-saving. When the insulation structure is worn or the sealing rubber ring is corroded and aged, the insulation and sealing performance can be restored by replacing the corresponding parts, which is convenient, fast, and cost-saving. Description of the Drawings

[0022] Figure 1Three-dimensional structural schematic diagram of a tubular combined cathode tool for centralized electric field side drainage; Figure 2 Exploded view of the structure of a tubular combined cathode tool for centralized electric field side drainage; Figure 3 Structural schematic diagram of a tubular cathode; Figure 4 Structural schematic diagram of an inner insulating shell; Figure 5 Structural schematic diagram of a sealing rubber ring; Figure 6 Structural schematic diagram of a semi-circular pipe shell; Figure 7 Process flow chart of rotary cathode electrochemical milling using a tubular combined cathode tool for centralized electric field side drainage; Figure 8 Comparison diagram of rotary cathode electrochemical milling and ordinary rotary electrode electrochemical milling using a tubular combined cathode tool for centralized electric field side drainage; Among them, the label names are: 1. Tubular cathode; 2. Inner insulating shell; 3. Sealing rubber ring; 4. Outer insulating shell; 5. Gasket; 6. Bolt; 7. Nut; 8. Positioning screw; 9. Set screw; 10. Workpiece; 11. Ordinary rotary electrode; 12. Side drainage port; 13. Axial unit flow channel; 14. Rectangular tool alignment boss; 15. Radial boss; 16. Side drainage holes on the inner insulating shell; 17. Radial threaded through hole; 18. Radial threaded blind hole; 19. Tool alignment groove; 20. Side drainage holes on the outer insulating shell; 21. Central through hole; 22. Side drainage holes on the sealing rubber ring. Specific implementation mode

[0023] The following further elaborates on the present invention in conjunction with the attached drawings: As Figure 1 and Figure 2 shown, a tubular combined cathode tool for centralized electric field side drainage proposed by the present invention includes a tubular cathode 1, an inner insulating shell 2, a sealing rubber ring 3, an outer insulating shell 4, a gasket 5, a bolt 6, a nut 7, a positioning screw 8, and a set screw 9. This tubular combined cathode tool consists of an inner and an outer layer. The inner layer is the tubular cathode 1, and the outer layer is an insulating and sealing shell, which includes an inner insulating shell 2, a sealing rubber ring 3, and an outer insulating shell 4. As shown in the figure, two square side drainage ports 12 are circumferentially arranged on the lower end wall of the tubular cathode 1, and the insulating and sealing shell is provided with a side drainage hole structure corresponding to the position and shape of the side drainage ports 12. The bottommost end of the side drainage ports 12 of the tubular cathode 1 is located above the bottom surface of the tubular cathode 1, and the height from its bottom surface is 2 to 5 times the thinnest wall thickness value of the tubular cathode 1. The inside of the tubular cathode 1 is divided into two axial unit flow channels 13 by a partition, and each axial unit flow channel 13 corresponds to and communicates with a side drainage port 12.

[0024] Figure 3 FIG.

[0024] is a schematic structural view of the tubular cathode 1. The upper left is the front view, the upper right is the half-sectional left view, the lower left is the top view, and the lower right is the orthographic isometric view. The tubular cathode 1 is a circular tube electrode, which is divided into two cylindrical structures in the upper and lower parts. The outer diameter of the upper cylindrical structure is larger than that of the lower cylindrical structure, so that the stepped surface where the two parts meet can be used as a positioning surface. The inside of the tubular cathode 1 is divided into two axial unit flow channels 13 by a partition. Two square lateral drain ports 12 are arranged along the circumferential direction of the lower end wall, corresponding to and communicating with the two axial unit flow channels 13 respectively. Therefore, it can be seen from the half-sectional left view that two clearly separated flow channels are formed on the left and right. In addition, in order to promote the more smooth discharge of the electrolyte from the lateral drain port 12 of the tubular cathode 1, the bottom surface of the lateral drain port 12 can also be designed as an inclined surface inclined towards the axis direction.

[0025] Figure 4 FIG. Figure 3 is a schematic structural view of the inner insulating shell 2. The upper left is the bottom view, the upper right is the orthographic isometric view, the lower left is the front view, and the lower right is the half-sectional left view. The inner insulating shell 2 is a tubular structure, and its inner diameter is equal to the outer diameter of the lower cylindrical structure of the tubular cathode 1, so that the inner insulating shell 2 can be directly sleeved on the lower cylindrical structure of the tubular cathode 1; its outer circle is divided into an upper outer circle part and a lower outer circle part, and the diameter of the upper outer circle part is larger than that of the lower outer circle part. Four radial threaded through holes 17 are evenly arranged along the circumferential direction of the upper outer circle part of the inner insulating shell 2, and two rectangular tool setting bosses 14 extending downward are evenly arranged along the circumferential direction. Each rectangular tool setting boss 14 is provided with a radial threaded blind hole 18. The inner insulating shell side drain holes 16 can be formed by screwing the set screws 9 into the four radial threaded through holes 17 until they tightly abut against the outer circle of the lower cylindrical structure of the tubular cathode 1 to realize the fixation of the two. Directly below the two rectangular tool setting bosses 14, a radial boss 15 is provided on the lower outer circle part of the inner insulating shell 2, and each radial boss 15 is provided with a square radial inner insulating shell side drain hole 16 at the center. Similarly, the bottom surface of the inner insulating shell side drain hole 16 can also be set as an inclined surface inclined towards the axis direction, and its contour shape on the inner wall is the same as the contour shape of the lateral drain port 12 on the outer circle of the tubular cathode 1. A chamfer is also provided at the bottom end of the lower outer circle part of the inner insulating shell 2. This chamfer can not only guide the nesting of the flexible sealing rubber ring 3, but also increase the space for the flexible sealing rubber ring 3 to be extruded downward for sealing.

[0026] Figure 6Schematic diagram of the semi-circular tube housing of the outer insulation housing 4. The upper left is the front view, the upper right is the full-section left view, the lower left is the top view, and the lower right is the orthographic axonometric view. The outer insulation housing 4 is formed by splicing a pair of semi-circular tube housings, and its inner wall is composed of an upper inner wall, a middle inner wall, and a lower inner wall. The inner diameter of the upper inner wall of the outer insulation housing 4 is equal to the outer diameter of the upper outer circular part of the inner insulation housing 2, and a central through hole 21 is opened in its center. The inner diameter of the middle inner wall of the outer insulation housing 4 is equal to the outer diameter of the lower outer circular part of the inner insulation housing 2, and a pair of tool setting grooves 19 matching the rectangular tool setting boss 14 are provided at both ends thereof (i.e., the splicing place of the semi-circular tube housings). The inner diameter of the lower inner wall of the outer insulation housing 4 is equal to the outer diameter of the radial boss 15 on the lower outer circular part of the inner insulation housing 2, and an outer insulation housing side discharge hole 20 is opened in its center, and the shape and size are the same as the contour shape of the inner insulation housing side discharge hole 16 on the radial boss 15 of the inner insulation housing 2. Three through holes are longitudinally opened on each splicing wing plate of the semi-circular tube housing.

[0027] Figure 5 Schematic diagram of the structure of the sealing rubber ring 3. The sealing rubber ring 3 is a flexible circular tube structure, and a pair of sealing rubber ring side discharge holes 22 are symmetrically opened about the axis. The inner diameter of the sealing rubber ring 3 is in interference fit with the outer diameter of the lower outer circular part of the inner insulation housing 2, and the outer diameter of the sealing rubber ring 3 is in interference fit with the inner diameter of the lower inner wall of the outer insulation housing 4. The shape of the sealing rubber ring side discharge hole 22 is the same as the outer contour of the radial boss 15 on the lower outer circular part of the inner insulation housing 2; the length of the sealing rubber ring 3 is slightly greater than the height of the lower inner wall of the outer insulation housing 4. Therefore, the thickness of the flexible sealing rubber ring 3 is greater than the gap between the lower outer circular part of the inner insulation housing 2 and the lower inner wall of the outer insulation housing 4 when not under force, and the length is slightly larger, and it will always be squeezed between the inner and outer insulation housings to accumulate sufficient elastic potential energy, and can timely supplement and block the depression after the removal of the processed surface material.

[0028] Through Figure 2The installation process of the tubular combined cathode tool for side drainage of the concentrated electric field can be understood. The inner insulating shell 2 is sleeved on the lower cylindrical structure of the tubular cathode 1 from bottom to top, so that the top surface of the inner insulating shell 2 contacts and is coplanar with the stepped surface where the upper and lower parts of the tubular cathode 1 are demarcated. At the same time, the inner insulating shell side drain holes 16 on the lower outer circular part of the inner insulating shell 2 are aligned with the lateral drain ports 12 at the bottom of the tubular cathode 1. Then, set screws 9 are screwed into the four radial threaded through holes 17 on the upper outer circular part of the inner insulating shell 2 until they tightly abut against the outer circle of the lower cylindrical structure of the tubular cathode 1 to complete the fixation of the two. Next, the sealing rubber ring 3 is nested on the lower outer circular part of the inner insulating shell 2 from bottom to top, and its radial sealing rubber ring side drain holes 22 are sleeved on the radial boss 15 on the lower outer circular part of the inner insulating shell 2. Then, the two semi-cylindrical shell bodies of the outer insulating shell 4 are aligned and spliced along the radial direction and wrap the inner insulating shell 2 and the sealing rubber ring 3 until the tool alignment grooves 19 on the inner wall of the middle of the outer insulating shell 4 all contact the rectangular tool alignment bosses 14 extending from the upper outer circular part of the inner insulating shell 2, and the entire outer circular surface of the sealing rubber ring 3 contacts the lower inner wall of the outer insulating shell 4. Finally, six bolts 6 with washers 5 sleeved are inserted into the through holes aligned in pairs on the wing plates of the pair of semi-cylindrical shell bodies, and the nuts 7 are tightened to complete the fixed connection of the two semi-cylindrical shell bodies. The assembly obtained by the above installation method is not the machining state of the combined tool, but its tool alignment state, which is to ensure that each component can be accurately positioned, tightly fixed, and airtight. The process of switching to the machining state is as follows: After ensuring that the sealing rubber ring 3 wraps the bottom of the inner insulating shell 2, press the two semi-cylindrical shell bodies fixedly connected together so that the upper surface of the inner wall of the middle of the outer insulating shell 4 drops to be coplanar with the bottom surface of the rectangular tool alignment boss 14 extending from the upper outer circular part of the inner insulating shell 2. Rotate the outer insulating shell 4 relative to the inner insulating shell 2 so that the central through hole 21 on the upper inner wall of the outer insulating shell 4 is aligned with the radial threaded blind hole 18 on the rectangular tool alignment boss 14 extending from the upper outer circular part of the inner insulating shell 2. Finally, insert the positioning screw 8 and tighten it to fix the relative positions of the inner insulating shell 2 and the outer insulating shell 4. The upper surface of the inner wall of the middle of the outer insulating shell 4 abuts against the bottom surface of the rectangular tool alignment boss 14 extending from the upper outer circular part of the inner insulating shell 2, and the lower surface of the inner wall of the middle of the outer insulating shell 4 presses the upper surface of the sealing rubber ring 3 to ensure that the space between the lower outer circular part of the inner insulating shell 2 and the lower inner wall of the outer insulating shell 4 is filled and sealed by the sealing rubber ring 3. At the same time, the outer insulating shell side drain hole 20 at the center of the lower inner wall of the outer insulating shell 4 is also aligned with the inner insulating shell side drain hole 16 on the lower outer circular part of the inner insulating shell 2. Thus, the assembly positioning of the combined tool in the machining state is completed, as shown in Figure 7(d) and (e). Therefore, there is no need to repeatedly disassemble and assemble. With simple rotation and positioning, it can be flexibly switched between the tool setting state and the machining state. Moreover, in the machining state, the upper surface of the inner wall of the outer insulating shell 4 abuts against the bottom surface of the rectangular tool setting boss 14 extending from the outer circular part of the inner insulating shell 2. Therefore, the distance from the bottom surface of the rectangular tool setting boss 14 extending from the outer circular part of the inner insulating shell 2 to the bottom surface of the inner insulating shell 2 is equal to the sum of the heights of the middle and lower inner walls of the outer insulating shell 4, ensuring that the bottom surfaces of the inner insulating shell 2 and the outer insulating shell 4 are coplanar in the machining state.

[0029] Figure 7 It is a process flow chart of rotary cathode electrochemical milling using a tubular combined cathode tool for side drainage by a concentrated electric field. As Figure 7 shown in (a), first, the tubular combined cathode tool for side drainage by a concentrated electric field needs to be installed on the machine tool and the workpiece 10 needs to be clamped. The tubular cathode 1 is connected to the negative pole of the power supply and vertically clamped on the main shaft of the machine tool, and the workpiece 10 is connected to the positive pole of the power supply. Since tool setting generally occurs between two machining operations, it is usually switched from the machining state to the tool setting state. Remove the positioning screw 8 and rotate the outer insulating shell 4 relative to the inner insulating shell 2 so that the two rectangular tool setting bosses 14 of the inner insulating shell 2 are respectively located directly above the tool setting grooves 19 at the joint of the inner walls of the outer insulating shell 4. Figure 7 Figure (a) is a view of the tool setting groove 19 at one end of the inner wall of the outer insulating shell 4 after rotation, where there is no positioning screw 8 screwed into the central through hole 21 on the upper inner wall of the outer insulating shell 4.

[0030] Then push the outer insulating shell 4 upward until each tool setting groove 19 of the outer insulating shell 4 is in contact and cooperation with the rectangular tool setting boss 14 of the inner insulating shell 2. At the same time, lift the exposed sealing rubber ring 3 upward and outward to support the outer insulating shell 4 and expose the bottom of the inner insulating shell 2. Move the main shaft of the machine tool for tool setting until the bottom surface of the inner insulating shell 2 just touches the upper surface of the workpiece 10, completing the tool setting, as Figure 7 shown in (b). From Figure 7 the upper local enlarged view of (b), it can be seen that the bottom surface of the inner insulating shell 2 just touches the upper surface of the workpiece 10, while there is a certain gap between the bottom surface of the tubular cathode 1 and the upper surface of the workpiece 10, which is the machining gap. Therefore, the total height of the inner insulating shell 2 is equal to the sum of the height of the lower cylindrical structure of the tubular cathode 1 and the height of the initial machining gap for electrochemical milling. In this way, the positioning of the tool electrode 1 can be completed through the positioning of the inner insulating shell 2.

[0031] After the tool setting is completed, then lower the lifted sealing rubber ring 3 so that it wraps the bottom of the inner insulating shell 2 again, and press the outer insulating shell 4 so that the upper surface of the middle inner wall of each semi-cylindrical shell of the outer insulating shell 4 drops to be coplanar with the bottom surface of the rectangular tool setting boss 14 extending from the outer circular part of the inner insulating shell 2, as Figure 7 shown in (c). Figure 7 The left and right views in (c) are cross-sectional views of two mutually perpendicular sections.

[0032] Rotate the outer insulating shell 4 relative to the inner insulating shell 2 so that the central through hole 21 on the upper inner wall of the outer insulating shell 4 is aligned with the radial threaded blind hole 18 provided on the rectangular tool alignment boss 14 of the inner insulating shell 2. Finally, insert the positioning screw 8 and tighten it to fix the relative positions of the inner insulating shell 2 and the outer insulating shell 4. The upper surface of the middle inner wall of the outer insulating shell 4 abuts against the bottom surface of the rectangular tool alignment boss 14 extending from the outer circular part of the inner insulating shell 2, and the lower surface of the middle inner wall of the outer insulating shell 4 presses against the top surface of the sealing rubber ring 3 to ensure that the space between the lower outer circular part of the inner insulating shell 2 and the lower inner wall of the outer insulating shell 4 is filled and sealed. At the same time, the outer insulating shell side drain hole 20 in the center of the lower inner wall of the outer insulating shell 4 is also aligned with the inner insulating shell side drain hole 16 on the radial boss 15 of the inner insulating shell 2. Thus, the assembly positioning in the processing state of the combined tool is completed, as Figure 7 shown in (d). Input the electrolyte so that the electrolyte flows through the tubular cathode 1 via the main shaft to the machining area of the workpiece 10, and apply electricity to the tubular cathode 1 and the workpiece 10. The main shaft of the machine tool drives the tubular cathode 1 to rotate and feed simultaneously. The material of the workpiece 10 directly below the tubular cathode 1 dissolves under the action of electrolysis and generates a large number of insoluble electrolysis product particles, and pits appear on the surface of the workpiece 10.

[0033] After machining and feeding for a period of time, a groove is machined and dissolved on the surface of the workpiece 10, as Figure 7 shown in (e). Since the thickness of the flexible sealing rubber ring 3 is greater than the gap between the inner insulating shell 2 and the outer insulating shell 4 when not under force, and its length is slightly greater than the height of the lower inner wall of the outer insulating shell 4, it is always squeezed between the inner and outer insulating shells 4 to accumulate sufficient elastic potential energy, which can timely block the depressions on the machined surface and prevent the electrolyte from diffusing outward through the depressions on the machined surface. The electrolyte carrying the machining products can only be discharged in large quantities from the side drain port 12 of the tubular cathode 1 through the inner insulating shell side drain hole 16 and the outer insulating shell side drain hole 20 in sequence.

[0034] Figure 8 It is a comparison diagram of rotary cathode electro-milling using a tubular combined cathode tool with side drainage by a concentrated electric field and ordinary rotary electrode electro-milling. Figure 8 Figure (a) is a schematic diagram of the flow field of rotary cathode electro-milling using a tubular combined cathode tool with side drainage by a concentrated electric field; Figure 8 Figure (b) is a schematic diagram of the electric field of rotary cathode electro-milling using a tubular combined cathode tool with side drainage by a concentrated electric field; Figure 8 Figure (c) is a schematic diagram of the flow field of ordinary rotary electrode electro-milling; Figure 8 Figure (d) is a schematic diagram of the electric field of ordinary rotary electrode electro-milling.

[0035] As Figure 8As shown in (c), during ordinary rotary electrode electrochemical milling, the electrolyte flows through the spindle and the ordinary rotary electrode 11 to the machining area of the workpiece 10, and the ordinary rotary electrode 11 and the workpiece 10 are energized. The material of the workpiece 10 below the ordinary rotary electrode 11 dissolves under the action of electrolysis and generates a large amount of insoluble electrolysis products. The electrolyte vertically impacting the surface of the workpiece 10 overflows horizontally in all directions, diffuses outward through the extremely narrow machining gap. While the flow direction changes suddenly, the hydraulic pressure and flow rate continuously change due to the compression of the extremely narrow gap, and the flow field is very disordered. The electrolyte carrying a large amount of electrolysis products cannot be quickly discharged, so naturally many product particles remain in the machining gap. Moreover, some products overflow from the machining gap to the machined surface with the electrolyte and adhere to the machined surface, damaging the machining surface quality. During the rotary cathode electrochemical milling with side drainage of the concentrated electric field proposed by the present invention, as Figure 8 shown in (a), the inner insulating shell 2, the sealing rubber ring 3 and the outer insulating shell 4 provide a three-layer insulation seal of rigid + flexible + rigid. The electrolyte can no longer overflow outward from the machining gap, but is discharged obliquely upward in a large flow rate from the side drainage port 12 at the bottom of the tubular cathode 1 with a larger liquid outlet area. This not only speeds up the discharge of electrolysis products, but also can shoot the products farther, avoiding falling and adhering to the machined surface and the area to be machined, and significantly improving the machining surface quality. The electrolyte with high cleanliness in the machining gap can maintain high conductivity and high material removal rate.

[0036] As Figure 8 shown in (d), during ordinary rotary electrode electrochemical milling, the electric field generated by the ordinary rotary electrode 11 will diffuse outward. Especially at the junction of the bottom surface and the outer circle of the ordinary rotary electrode 11, the electric field edge diffusion effect is obvious, and a low current density area will be formed in the machined surface and the area to be machined, which not only wastes power supply, but also causes secondary electrolysis and stray corrosion of the machined surface, and at the same time damages the machining efficiency and the machining surface quality. During the rotary cathode electrochemical milling with side drainage of the concentrated electric field proposed by the present invention, as Figure 8 shown in (b), the electric field is restricted by the three-layer insulation and cannot diffuse outward. The electric quantity is concentrated in the projection area directly below the tubular cathode 1, which improves the machining current density and significantly improves the machining accuracy and localization.

[0037] The present invention controls both the electric field and the flow field. On the one hand, it guides the electrolyte carrying the processed product to discharge in a large flow rate from the lateral drainage port 12 at the bottom of the tubular cathode 1, avoiding the adhesion of the product to the processed surface and ensuring the high conductivity of the electrolyte in the machining gap. On the other hand, it concentrates the electric field in the projection area directly below the tubular cathode 1, improving the machining current density, avoiding stray corrosion, and simultaneously achieving significant improvements in machining accuracy, machining localization, machining efficiency, and machining surface quality. However, the above description should not be construed as a limitation of the present invention's patent. It should be noted that several improvements can be made without departing from the concept of the present invention, and these should all fall within the protection scope of the present invention's patent.

Claims

1. A tubular combined cathode tool, consisting of an inner and outer layer, the inner layer being a tubular cathode (1) and the outer layer being an insulating sealed shell, characterized in that: The lower end of the insulating sealing shell protrudes beyond the tubular cathode (1), and the protruding portion is flexible, and the protruding portion is used to supplement the sealing of the depression after the processed surface material is removed; a plurality of lateral liquid discharge ports (12) are arranged along the circumferential direction on the tube wall at the lower end of the tubular cathode (1), and a lateral discharge hole structure corresponding to the position of the lateral liquid discharge ports (12) and matching in shape is arranged on the insulating sealing shell.

2. The tubular combined cathode tool according to claim 1, characterized in that: The lateral liquid discharge port (12) of the tubular cathode (1) is polygonal or circular.

3. The tubular combined cathode tool according to claim 1, characterized in that: The bottom end of the lateral liquid discharge port (12) of the tubular cathode (1) is located above the bottom surface of the tubular cathode (1), and the height from the bottom surface is 2 to 5 times the thinnest wall thickness of the tubular cathode (1).

4. The tubular combined cathode tool according to claim 1, characterized in that: The interior of the tubular cathode (1) is divided into a plurality of axial unit flow channels (13) by a partition, and each axial unit flow channel (13) corresponds to and is connected to a lateral liquid discharge port (12).

5. The tubular combined cathode tool according to any one of claims 1 to 4, characterized in that: The insulating sealed shell comprises an inner insulating shell (2), a sealing rubber ring (3) and an outer insulating shell (4); The tubular cathode (1) is a circular tube electrode, which is divided into an upper cylindrical structure and a lower cylindrical structure, wherein the outer diameter of the upper cylindrical structure is greater than the outer diameter of the lower cylindrical structure; The inner insulating shell (2) is a tubular structure, and its inner diameter is equal to the outer diameter of the cylindrical structure at the lower part of the tubular cathode (1); the outer circle of the inner insulating shell (2) is divided into an upper outer circle part and a lower outer circle part, and the diameter of the upper outer circle part is larger than the diameter of the lower outer circle part; the upper outer circle part of the inner insulating shell (2) is evenly provided with two rectangular tool-setting bosses (14) extending downward along the circumferential direction; its lower outer circle part is provided with a radial boss (15) directly below the rectangular tool-setting boss (14), and the radial boss (15) is provided with inner insulating shell side holes (16); The outer insulating shell (4) is composed of a pair of semi-circular tube shells spliced ​​together, and the inner wall of the outer insulating shell (4) is composed of an upper inner wall, a middle inner wall, and a lower inner wall; wherein the inner diameter of the upper inner wall is equal to the outer diameter of the upper outer circular portion of the inner insulating shell (2), the inner diameter of the middle inner wall is equal to the outer diameter of the lower outer circular portion of the inner insulating shell (2), and the inner diameter of the lower inner wall is equal to the outer diameter of the radial boss (15) on the lower outer circular portion of the inner insulating shell (2); the middle inner wall of the outer insulating shell (4) is provided with a tool setting groove (19) matching the rectangular tool setting boss (14) at the splicing position of the semi-circular tube shells; and the lower inner wall of the outer insulating shell (4) is provided with outer insulating shell side row holes (20); The sealing rubber ring (3) is a flexible circular tube structure, the inner diameter of which is interference fit with the outer diameter of the lower outer circular part of the inner insulating shell (2), and the outer diameter of which is interference fit with the inner diameter of the lower inner wall of the outer insulating shell (4); the length of the sealing rubber ring (3) exceeds the height of the lower inner wall of the outer insulating shell (4), and the excess part is used to supplement the sealing of the depression after the processed surface material is removed; the sealing rubber ring (3) is provided with sealing rubber ring side holes (22); The lateral liquid discharge port (12), the inner insulating shell side discharge holes (16), the sealing rubber ring side discharge holes (22), and the outer insulating shell side discharge holes (20) of the tubular electrode correspond to each other in position and have matching structures and shapes; The inner insulating shell (2) is sleeved on the cylindrical structure of the lower part of the tubular cathode (1) from bottom to top, and the top surface of the inner insulating shell (2) is in contact with the step surface dividing the upper and lower parts of the tubular cathode (1) and is coplanar; a plurality of radial threaded through holes (17) are arranged along the circumference of the upper outer circumference of the inner insulating shell (2), and the outer circumference of the cylindrical structure of the lower part of the tubular cathode (1) is pressed against by a set screw (9) in the radial threaded through hole (17) to complete the fixation of the two; a radial threaded blind hole (18) is also provided on the rectangular tool-setting boss (14) of the inner insulating shell (2); The sealing rubber ring (3) is nested on the lower outer circumference of the inner insulating shell (2) from bottom to top, and its sealing rubber ring side row holes (22) are sleeved on the radial boss (15) of the lower outer circumference of the inner insulating shell (2); The two semi-circular tube shells of the outer insulating shell (4) are aligned and assembled along the radial direction and wrap the inner insulating shell (2) and the sealing rubber ring (3), so that the upper surface of the middle inner wall of the outer insulating shell (4) abuts against the bottom surface of the rectangular tool-matching boss (14) extending from the upper outer circular part of the inner insulating shell (2), and at the same time, the lower surface of the middle inner wall of the outer insulating shell (4) presses the top surface of the sealing rubber ring (3), so that the entire outer circular surface of the sealing rubber ring (3) is in contact with the lower inner wall of the outer insulating shell (4); a central through hole (21) is also opened in the center of the upper inner wall of the semi-circular tube shell of the outer insulating shell (4), and the outer insulating shell (4) is connected and positioned in the central through hole (21) with a radial threaded blind hole (18) provided on the rectangular tool-matching boss (14) of the inner insulating shell (2) by a positioning screw (8).

6. The tubular combined cathode tool according to claim 5, characterized in that: The total height of the inner insulating shell (2) is equal to the sum of the height of the cylindrical structure of the lower part of the tubular cathode (1) and the height of the initial machining gap of the electrolytic milling; the distance from the bottom surface of the rectangular tool boss (14) extending from the upper outer circular part of the inner insulating shell (2) to the bottom surface of the inner insulating shell (2) is equal to the sum of the heights of the middle inner wall and the lower inner wall of the outer insulating shell (4).

7. The tubular combined cathode tool according to claim 5, characterized in that: The tubular cathode (1) is made of metal material, the inner insulating shell (2) and the outer insulating shell (4) are made of rigid insulating material, and the sealing rubber ring (3) is made of latex or silicone insulating material.

8. The tubular combined cathode tool according to claim 7, characterized in that: The rigid insulating material is polyetheretherketone (PEEK) or polyoxymethylene (POM).

9. A rotary cathode electrolytic milling method using the tubular combined cathode tool according to claim 5, characterized in that The process includes: Step 1: tool setting: the tubular cathode (1) is connected to the negative pole of the power supply and is vertically clamped on the machine tool spindle, and the workpiece (10) is connected to the positive pole of the power supply; the positioning screw (8) is removed, and the outer insulating shell (4) is rotated relative to the inner insulating shell (2) so that the two rectangular tool setting bosses (14) of the inner insulating shell (2) are respectively located directly above the tool setting grooves (19) at the joint of the inner wall of the outer insulating shell (4); then the outer insulating shell (4) is pushed upward until each tool setting groove (19) of the outer insulating shell (4) contacts and cooperates with the rectangular tool setting boss (14) of the inner insulating shell (2), and at the same time, the exposed sealing rubber ring (3) is lifted upward and outward to support the outer insulating shell (4) and expose the bottom of the inner insulating shell (2); the machine tool spindle is moved to perform tool setting until the bottom surface of the inner insulating shell (2) just contacts the upper surface of the workpiece (10), and the tool setting is completed; Next, the lifted sealing rubber ring (3) is lowered to wrap the bottom of the inner insulating shell (2) again, and the outer insulating shell (4) is pressed down so that the upper surface of the middle inner wall of each semi-circular tube shell of the outer insulating shell (4) is lowered to be coplanar with the bottom surface of the rectangular tool-setting boss (14) of the inner insulating shell (2); then, the outer insulating shell (4) is rotated relative to the inner insulating shell (2) so that the central through hole (21) on the upper inner wall of the outer insulating shell (4) is aligned with the radial threaded blind hole (18) provided on the rectangular tool-setting boss (14) of the inner insulating shell (2); finally, the positioning screw (8) is inserted and tightened to fix the inner insulating shell (2) and the outer insulating shell (4) ), the upper surface of the inner wall of the outer insulating shell (4) abuts against the bottom surface of the rectangular tool-matching boss (14) extending from the upper outer circular portion of the inner insulating shell (2), and the lower surface of the inner wall of the outer insulating shell (4) presses against the top surface of the sealing rubber ring (3), ensuring that the space between the lower outer circular portion of the inner insulating shell (2) and the lower inner wall of the outer insulating shell (4) is filled and sealed, and at the same time, the outer insulating shell side row holes (20) on the lower inner wall of the outer insulating shell (4) are also aligned with the inner insulating shell side row holes (16) on the radial boss (15) of the inner insulating shell (2), thereby completing the assembly positioning of the tubular combined cathode tool in the processing state; Step 2, processing: inputting electrolyte, allowing the electrolyte to flow through the main shaft through the tubular cathode (1) to the processing area of ​​the workpiece (10), and energizing the tubular cathode (1) and the workpiece (10); the material of the workpiece (10) directly below the tubular cathode (1) is dissolved under the action of electrolysis and a large amount of insoluble electrolysis product particles are generated; because the inner insulating shell (2), the sealing rubber ring (3) and the outer insulating shell (4) provide a three-layer insulation seal of rigidity + flexibility + rigidity, the electrolyte is prevented from diffusing outward through the processing gap, and the electrolyte carrying the processing product can only be discharged from the lateral discharge port (12) of the tubular cathode (1). The large flow rate discharge ensures the high cleanliness and high conductivity of the electrolyte in the processing gap, significantly improving the processing surface quality and material removal rate; the electric field is restricted by the three layers of insulation and cannot diffuse outward, and the electricity is concentrated in the projected area directly below the tubular cathode (1), thereby increasing the processing current density and significantly improving the processing accuracy and localization; the three-layer insulation sealing structure simultaneously constrains the electric field and the flow field, not only avoiding the adhesion and contamination of the electrolytic products on the processed surface, but also suppressing the edge diffusion effect of the electric field, eliminating the secondary damage to the processed surface, preventing the generation of stray corrosion, and significantly improving the processing surface quality.

Images