Deep cavity electrolytic machining method and device

Abstract

The invention relates to a deep cavity electrolytic machining method which is achieved through a deep cavity electrolytic machining device. The deep cavity electrolytic machining device comprises an outer cathode and an inner cathode, and the outer cathode is arranged on the outer side of the inner cathode in a sleeving mode. An inner insulating layer is arranged on the inner side of the outer cathode, and an outer insulating layer is arranged on the outer side; a channel for electrolyte to flow is arranged in the middle of the inner cathode; the deep cavity electrolytic machining method comprises the steps that the inner cathode is controlled to be kept static, the outer cathode is driven to move along the outer side of the inner cathode to conduct feeding machining on a workpiece, and electrolyte is sprayed out from the middle of the inner cathode; when the feeding depth of the outer cathode reaches the preset depth, the outer cathode is controlled to stop feeding and keep still, and the inner cathode is driven to move to conduct feeding machining on the workpiece; and when the inner cathode is fed to a preset depth, the inner cathode is controlled to stop feeding, and the outer cathode and the inner cathode are withdrawn from the workpiece. The problem that the size and shape are difficult to guarantee due to side wall corrosion in the deep special-shaped cavity machining process can be solved, and the side wall machining precision and the surface quality are improved.

Description

Technical Field

[0001] The present application relates to the technical field of electrochemical machining, and in particular to a deep cavity electrolytic machining method and device. Background Art

[0002] In the field of aviation and aerospace manufacturing, a large number of deep special-shaped cavity structures have appeared on the load-bearing structures, and the processing method is generally CNC mechanical milling. The main problem is that the efficiency is not high when processing deep cavities, and processing to thin walls of the cavity will cause deformation due to processing stress. In recent years, electrolytic processing has become an important technical direction for deep cavity processing. Electrolytic processing is a special process method that uses the principle of electrochemical anode dissolution to remove metal. During electrolytic processing, the tool electrode is the cathode and the workpiece is the anode. During electrolytic processing, a certain gap is maintained between the workpiece anode and the tool cathode, and a DC voltage is applied between the electrodes. The electrolyte generally uses a neutral salt solution to form an electrochemical reaction cell between the electrodes. At the same time, the high-speed flow continuously takes away the electrolysis products and heat and depolarizes. The workpiece continues to dissolve as the tool cathode is fed until the cavity size of the workpiece reaches the required size.

[0003] In deep cavity electrolytic machining, in addition to the electrochemical "anodic dissolution" processing of the cavity body, the lateral part of the processed part is always affected by the electrochemical field and is constantly corroded during the entire process of electrode feeding. After the processing, the side wall of the cavity will have a large slope and out of tolerance. Although many technical measures such as flow field improvement, pulse power supply, and insulation protection have been implemented in the past, the conformal problem of the cavity side wall has not been well solved. The continuous "anodic dissolution" process of electrolytic machining requires the establishment of a stable electrolyte flushing flow field, but in deep cavity electrolytic machining, the electrolyte flushing flow channel is too long and the flow field resistance is large. As the electrode enters the depth of the workpiece, the path through which the electrolyte flows becomes longer and longer, and the flow resistance of the electrolyte flowing along the gap between the electrode and the cavity side wall is large. The flow field flushing speed slows down, affecting the discharge of electrolytic products, causing electrochemical polarization in the machining area, and reducing the forming dimensional accuracy and surface quality of the cavity side wall. Summary of the invention

[0004] The present application provides a deep cavity electrolytic machining method and device, which solves the problem that the dimensional accuracy and surface quality of the formed parts cannot be guaranteed due to the corrosion of the cavity sidewalls during the machining of deep special-shaped cavities.

[0005] In a first aspect, the present application provides a deep cavity electrolytic machining method, which is implemented by a deep cavity electrolytic machining device; the deep cavity electrolytic machining device comprises an outer cathode and an inner cathode, the outer cathode is sleeved on the outer side of the inner cathode; an inner insulating layer is arranged on the inner side of the outer cathode, and an outer insulating layer is arranged on the outer side; a channel for electrolyte circulation is arranged in the middle of the inner cathode;

[0006] The deep cavity electrolytic machining method comprises:

[0007] Controlling the inner cathode to remain stationary, driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing, and the electrolyte is ejected from the middle of the inner cathode;

[0008] When the outer cathode feed reaches a preset depth, the outer cathode is controlled to stop feeding and remain stationary, and the inner cathode is driven to move to feed and process the workpiece;

[0009] When the inner cathode reaches the preset depth, the inner cathode is controlled to stop feeding, and the outer cathode and the inner cathode are retracted from the workpiece.

[0010] Furthermore, the deep cavity electrolytic machining device further comprises a DC power supply; the workpiece is connected to the positive electrode of the DC power supply, the inner cathode is connected to the negative electrode of the DC power supply via an inner cathode switch, and the outer cathode is connected to the negative electrode of the DC power supply via an outer cathode switch;

[0011] Before controlling the inner cathode to remain stationary and driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing, the method further includes:

[0012] The workpiece is controlled to be connected to the positive pole of the DC power supply, the inner cathode switch is disconnected, and the outer cathode switch is closed to connect the outer cathode to the negative pole of the DC power supply.

[0013] Furthermore, the deep cavity electrolytic machining device further comprises a machine tool cathode mounting plate and a cylinder, one end of the cylinder is connected to the machine tool cathode mounting plate, and the other end is connected to the outer cathode;

[0014] The step of driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece includes:

[0015] The cylinder is controlled to move so as to drive the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing.

[0016] Furthermore, after the outer cathode reaches a preset depth, the outer cathode is controlled to stop feeding and remain stationary, and before the inner cathode is driven to move to feed the workpiece, the method further includes:

[0017] The outer cathode switch is controlled to be opened, and the inner cathode switch is controlled to be closed so that the inner cathode is connected to the negative pole of the DC power supply.

[0018] Further, the inner cathode is connected to the machine tool cathode mounting plate;

[0019] The step of driving the inner cathode to move and feed the workpiece comprises:

[0020] The cathode mounting plate of the machine tool is controlled to move so as to drive the inner cathode to move and feed the workpiece for processing.

[0021] Further, after the inner cathode reaches the preset depth, before controlling the inner cathode to stop feeding and withdrawing the outer cathode and the inner cathode from the workpiece, it also includes:

[0022] The workpiece is controlled to be disconnected from the positive electrode of the DC power supply, the outer cathode switch is disconnected, and the inner cathode switch is disconnected.

[0023] Further, the step of withdrawing the outer cathode and the inner cathode from the workpiece comprises:

[0024] The machine tool cathode mounting plate is controlled to move so as to retract the outer cathode and the inner cathode from the workpiece.

[0025] In a second aspect, the present application provides a deep cavity electrolytic machining device for implementing the deep cavity electrolytic machining method as described above; the deep cavity electrolytic machining device comprises an outer cathode, an inner cathode, a DC power supply, a machine tool cathode mounting plate and a cylinder;

[0026] The outer cathode is sleeved on the outer side of the inner cathode; an inner insulating layer is provided on the inner side of the outer cathode, and an outer insulating layer is provided on the outer side; a channel for electrolyte flow is provided in the middle of the inner cathode;

[0027] The positive electrode of the DC power supply is connected to the workpiece, the inner cathode is connected to the negative electrode of the DC power supply through an inner cathode switch, and the outer cathode is connected to the negative electrode of the DC power supply through an outer cathode switch;

[0028] One end of the cylinder is connected to the machine tool cathode mounting plate, and the other end is connected to the outer cathode; the inner cathode is connected to the machine tool cathode mounting plate.

[0029] Furthermore, the deep cavity electrolytic machining device also includes a liquid collecting chamber, which is arranged between the machine tool cathode mounting plate and the inner cathode and is connected to the channel in the middle of the inner cathode.

[0030] Furthermore, pipe joints are respectively provided on both sides of the liquid collecting chamber, and the pipe joints are used to connect electrolyte tubes.

[0031] The above technical solution of the present application has the following advantages:

[0032] The deep cavity electrolytic machining method provided in the first aspect of the present application is realized by a deep cavity electrolytic machining device; the deep cavity electrolytic machining device includes an outer cathode and an inner cathode, the outer cathode is sleeved on the outer side of the inner cathode; an inner insulating layer is provided on the inner side of the outer cathode, and an outer insulating layer is provided on the outer side; a channel for electrolyte circulation is provided in the middle of the inner cathode. By using nested inner and outer cathodes for cavity machining, the outer cathode first feeds the workpiece to machine a groove, and after forming the side wall of the cavity, the outer cathode remains stationary to form a protective cover, and the inner and outer insulating layers can block the electric field between the machined side wall of the cavity and the electrode, play an insulating and protective role on the machined side wall of the cavity, prevent stray corrosion and secondary machining during the machining process, and improve the machining accuracy and surface quality of the side wall. When the inner cathode continues to machine a complete deep cavity, it will no longer have a corrosion effect on the side wall of the cavity, thereby ensuring the shape of the machined deep cavity.

[0033] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A schematic diagram of a deep cavity electrolytic machining device provided in this application;

[0036] Figure 2 A flow chart of the deep cavity electrolytic machining method provided in this application.

[0037] Figure numerals: 1. DC power supply; 2. Inner cathode switch; 3. Outer cathode switch; 4. Machine tool cathode mounting plate; 5. Pipe joint; 6. Liquid collecting chamber; 7. Cylinder; 8. Inner cathode; 9. Outer cathode; 10. Inner insulating layer; 11. Outer insulating layer; 12. Workpiece. DETAILED DESCRIPTION

[0038] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0039] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0040] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0041] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways. "Multiple" means "two or more".

[0042] Stray corrosion is a common phenomenon in the electrolytic machining process. It usually occurs in the low current density area near the non-machined surface of the machining area, which will cause uneven material dissolution on the non-machined surface of the workpiece, thereby affecting the electrolytic machining accuracy. When electrolytic machining the cavity, if a more active NaCl, KBr or composite electrolyte is used, the localization of material dissolution will deteriorate, which will aggravate the degree of stray corrosion on the cavity surface and affect the forming accuracy.

[0043] In view of the problems existing in the electrolytic machining technology of deep special-shaped cavity structures, such as poor machining stability caused by unfavorable electrolyte flushing when machining to a deep depth, large dimensional deviation caused by lateral corrosion, and difficulty in ensuring surface quality, the present application proposes a deep cavity electrolytic machining method and device to solve the problem of difficulty in ensuring size and shape due to side wall corrosion during machining of deep special-shaped cavities.

[0044] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0045] The present application provides a deep cavity electrolytic machining method, which is implemented by a deep cavity electrolytic machining device. Figure 1As shown, the deep cavity electrolytic machining device includes an outer cathode 9 and an inner cathode 8, wherein the outer cathode 9 is sleeved on the outer side of the inner cathode 8; an inner insulating layer 10 is provided on the inner side of the outer cathode 9, and an outer insulating layer 11 is provided on the outer side; a channel for electrolyte circulation is provided in the middle of the inner cathode 8.

[0046] like Figure 2 As shown, the deep cavity electrolytic machining method includes: controlling the inner cathode 8 to remain stationary, driving the outer cathode 9 to move along the outer side of the inner cathode 8 to feed the workpiece 12 for machining, and the electrolyte is sprayed from the middle of the inner cathode 8; when the outer cathode 9 feeds to a preset depth, controlling the outer cathode 9 to stop feeding and remain stationary, driving the inner cathode 8 to move to feed the workpiece 12 for machining; when the inner cathode 8 feeds to the preset depth, controlling the inner cathode 8 to stop feeding, and retracting the outer cathode 9 and the inner cathode 8 from the workpiece 12.

[0047] The embodiment of the present application adopts two cathodes, an inner cathode 8 and an outer cathode 9, in a nested form, and divides the deep cavity processing into two stages. In the first stage, the inner cathode 8 is stationary, and the outer cathode 9 feeds the workpiece 12 to process a groove of a preset depth along the contour of the cavity to be processed to form the side wall of the cavity. The inner insulating layer 10 and the outer insulating layer 11 can block the electric field between the processed cavity side wall and the electrode, play an insulating and protective role for the processed cavity side wall, prevent stray corrosion and secondary processing during the processing, and improve the side wall processing accuracy and surface quality. In the second stage, the outer cathode 9 stops feeding and remains stationary, and the inner cathode 8 feeds the workpiece 12 to remove the remaining material wrapped inside the outer cathode 9, and a complete deep cavity is processed, thereby ensuring the shape of the processed deep cavity.

[0048] The cavity is processed by using nested inner and outer cathodes. The outer cathode 9 is fed first for processing. After the cavity side wall is formed, the outer cathode 9 stops feeding and remains stationary to form a protective cover. When the inner cathode 8 continues to be processed, it no longer has a corrosive effect on the cavity side wall, thereby ensuring the shape of the processed deep cavity.

[0049] like Figure 1 As shown, in some embodiments, the deep cavity electrolytic machining device also includes a DC power supply 1; the workpiece 12 is connected to the positive pole of the DC power supply 1, the inner cathode 8 is connected to the negative pole of the DC power supply 1 through the inner cathode switch 2, and the outer cathode 9 is connected to the negative pole of the DC power supply 1 through the outer cathode switch 3.

[0050] Before controlling the inner cathode 8 to remain stationary and driving the outer cathode 9 to move along the outer side of the inner cathode 8 to feed the workpiece 12 for processing, the process also includes: controlling the workpiece 12 to be connected to the positive pole of the DC power supply 1, disconnecting the inner cathode switch 2, and closing the outer cathode switch 3 to connect the outer cathode 9 to the negative pole of the DC power supply 1.

[0051] like Figure 1 As shown, in some embodiments, the deep cavity electrolytic machining device further includes a machine tool cathode mounting plate 4 and a cylinder 7, one end of the cylinder 7 is connected to the machine tool cathode mounting plate 4, and the other end is connected to the external cathode 9.

[0052] The driving of the outer cathode 9 to move along the outer side of the inner cathode 8 to feed the workpiece 12 for processing includes: controlling the movement of the cylinder 7 to drive the outer cathode 9 to move along the outer side of the inner cathode 8 to feed the workpiece 12 for processing.

[0053] In some embodiments, after the outer cathode 9 has been fed to a preset depth, the outer cathode 9 is controlled to stop feeding and remain stationary, and before the inner cathode 8 is driven to move to feed the workpiece 12 for processing, it also includes: controlling the outer cathode switch 3 to disconnect and the inner cathode switch 2 to close so that the inner cathode 8 is connected to the negative pole of the DC power supply 1.

[0054] like Figure 1 As shown, in some embodiments, the inner cathode 8 is connected to the machine tool cathode mounting plate 4. The driving of the inner cathode 8 to move the workpiece 12 for feeding and processing includes: controlling the movement of the machine tool cathode mounting plate 4 to drive the inner cathode 8 to move the workpiece 12 for feeding and processing.

[0055] In some embodiments, after the inner cathode 8 reaches the preset depth, controlling the inner cathode 8 to stop feeding, and before retracting the outer cathode 9 and the inner cathode 8 from the workpiece 12, further includes: controlling the workpiece 12 to be disconnected from the positive pole of the DC power supply 1, the outer cathode switch 3 to be disconnected, and the inner cathode switch 2 to be disconnected.

[0056] In some embodiments, retracting the outer cathode 9 and the inner cathode 8 from the workpiece 12 includes: controlling the movement of the machine tool cathode mounting plate 4 to retract the outer cathode 9 and the inner cathode 8 from the workpiece 12 .

[0057] The cathode of the processing cavity is divided into two parts, namely the outer cathode 9 and the inner cathode 8. The outer cathode 9 is connected to the machine tool cathode mounting plate 4 through the symmetrically distributed cylinders 7, and the inner cathode 8 is directly fixed on the machine tool cathode mounting plate 4. During processing, the electrolyte is sprayed out from the middle of the inner cathode 8. In the first step, the inner cathode 8 is stationary, the outer cathode 9 is connected to the negative pole of the DC power supply 1, the workpiece 12 is connected to the positive pole of the DC power supply 1, and the outer cathode 9 is fed. After reaching the set depth, the feeding stops and the power supply of the outer cathode 9 is cut off; in the second step, the inner cathode 8 is connected to the negative pole of the DC power supply 1 and fed for processing. At this time, the outer cathode 9 plays a protective role for the side wall of the processed cavity.

[0058] The present application also provides a deep cavity electrolytic machining device for implementing the deep cavity electrolytic machining method as described above. Figure 1 As shown, the deep cavity electrolytic machining device includes an outer cathode 9, an inner cathode 8, a DC power supply 1, a machine tool cathode mounting plate 4 and a cylinder 7.

[0059] The outer cathode 9 is sleeved on the outside of the inner cathode 8; an inner insulating layer 10 is provided on the inner side of the outer cathode 9, and an outer insulating layer 11 is provided on the outer side; a channel for electrolyte circulation is provided in the middle of the inner cathode 8; the positive electrode of the DC power supply 1 is connected to the workpiece 12, the inner cathode 8 is connected to the negative electrode of the DC power supply 1 through the inner cathode switch 2, and the outer cathode 9 is connected to the negative electrode of the DC power supply 1 through the outer cathode switch 3; one end of the cylinder 7 is connected to the machine tool cathode mounting plate 4, and the other end is connected to the outer cathode 9; the inner cathode 8 is connected to the machine tool cathode mounting plate 4.

[0060] like Figure 1 As shown, in some embodiments, the deep cavity electrolytic machining device further includes a liquid collecting chamber 6, which is disposed between the machine tool cathode mounting plate 4 and the inner cathode 8 and is connected to a channel in the middle of the inner cathode 8.

[0061] like Figure 1 As shown, in some embodiments, pipe joints 5 are respectively provided on both sides of the liquid collecting chamber 6, and the pipe joints 5 are used to connect the electrolyte tubes.

[0062] The machining electrode can be installed on the cathode mounting plate 4 of the machine tool, and the cylinder 7 is actuated to push out the outer cathode 9 and maintain the thrust. During machining, the electrolyte is ejected from the middle of the inner cathode 8 through the electrolyte pipe through the liquid collecting chamber 6. The workpiece 12 is connected to the positive pole of the DC power supply 1, the outer cathode switch 3 is closed, and the outer cathode 9 is connected to the negative pole of the DC power supply 1, and the outer cathode 9 starts to feed.

[0063] After the outer cathode 9 is processed to the set depth, the feeding is suspended, the outer cathode switch 3 is disconnected, and at the same time, the inner cathode switch 2 is closed, and the inner cathode 8 is connected to the negative pole of the DC power supply 1. The pressure of the cylinder 7 is relieved, and the machine tool cathode mounting plate 4 moves downward to drive the inner cathode 8 to feed. The outer cathode 9 remains stationary, and a protective sleeve is formed at this time. Its inner insulating layer 10 protects the outer cathode 9 from corrosion, and the outer insulating layer 11 isolates the processing energy field of the processed cavity side wall part, playing a role in protecting the cavity side wall. When the inner cathode 8 is processed to the bottom of the cavity at the set depth, the DC power supply 1 is disconnected, the machine tool cathode mounting plate 4 is retracted, and the processing is completed.

[0064] The deep cavity electrolytic machining method and device provided in the embodiment of the present application are used to machine a titanium alloy deep cavity, the cavity cross-sectional size is 50mm×50mm, and the depth is 80mm. The electrolyte is a 10% KBr aqueous solution, the electrolyte temperature is 25°C; the electrolyte pressure is 0.6MPa; the machining voltage is 20V; after machining a given depth, the feed is stopped and the power is cut off. According to the test, under the above parameters, the side wall slope of the machined deep cavity is small, and the surface roughness reaches Ra3.2μm or less.

[0065] The deep cavity electrolytic machining method and device provided in the embodiment of the present application uses nested inner and outer cathodes to perform cavity machining. The outer cathode first feeds the workpiece to machine a groove. After the cavity sidewall is formed, the outer cathode remains stationary to form a protective sleeve. The inner and outer insulating layers can block the electric field between the machined cavity sidewall and the electrode, and play an insulating and protective role on the machined cavity sidewall, preventing stray corrosion and secondary machining during the machining process, and improving the sidewall machining accuracy and surface quality. When the inner cathode continues to machine a complete deep cavity, it no longer has a corrosion effect on the cavity sidewall, thereby ensuring the shape of the machined deep cavity.

[0066] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application.

[0067] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A deep cavity electrolytic machining method, characterized in that: The deep cavity electrolytic machining device is used for this purpose. The deep cavity electrolytic machining device comprises an outer cathode and an inner cathode. The outer cathode is sleeved on the outer side of the inner cathode. The inner side of the outer cathode is provided with an inner insulating layer, and the outer side is provided with an outer insulating layer. A channel for electrolyte circulation is provided in the middle of the inner cathode; The deep cavity electrolytic machining method comprises: Controlling the inner cathode to remain stationary, driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing, and the electrolyte is ejected from the middle of the inner cathode; When the outer cathode feed reaches a preset depth, the outer cathode is controlled to stop feeding and remain stationary, and the inner cathode is driven to move to feed and process the workpiece; When the inner cathode reaches the preset depth, the inner cathode is controlled to stop feeding, and the outer cathode and the inner cathode are retracted from the workpiece.

2. The deep cavity electrolytic machining method according to claim 1, characterized in that: The deep cavity electrolytic machining device further includes a DC power supply; the workpiece is connected to the positive electrode of the DC power supply, the inner cathode is connected to the negative electrode of the DC power supply via an inner cathode switch, and the outer cathode is connected to the negative electrode of the DC power supply via an outer cathode switch; Before controlling the inner cathode to remain stationary and driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing, the method further includes: The workpiece is controlled to be connected to the positive pole of the DC power supply, the inner cathode switch is disconnected, and the outer cathode switch is closed to connect the outer cathode to the negative pole of the DC power supply.

3. The deep cavity electrolytic machining method according to claim 1, characterized in that: The deep cavity electrolytic machining device also includes a machine tool cathode mounting plate and a cylinder, one end of the cylinder is connected to the machine tool cathode mounting plate, and the other end is connected to the outer cathode; The step of driving the outer cathode to move along the outer side of the inner cathode to feed the workpiece includes: The cylinder is controlled to move so as to drive the outer cathode to move along the outer side of the inner cathode to feed the workpiece for processing.

4. The deep cavity electrolytic machining method according to claim 2, characterized in that: After the outer cathode reaches a preset depth, the outer cathode is controlled to stop feeding and remain stationary, and before the inner cathode is driven to move to feed the workpiece, the process further includes: The outer cathode switch is controlled to be opened, and the inner cathode switch is controlled to be closed so that the inner cathode is connected to the negative pole of the DC power supply.

5. The deep cavity electrolytic machining method according to claim 3, characterized in that: The inner cathode is connected to the machine tool cathode mounting plate; The step of driving the inner cathode to move and feed the workpiece comprises: The cathode mounting plate of the machine tool is controlled to move so as to drive the inner cathode to move and feed the workpiece for processing.

6. The deep cavity electrolytic machining method according to claim 2, characterized in that: After the inner cathode reaches the preset depth, before controlling the inner cathode to stop feeding and withdrawing the outer cathode and the inner cathode from the workpiece, the method further includes: The workpiece is controlled to be disconnected from the positive electrode of the DC power supply, the outer cathode switch is disconnected, and the inner cathode switch is disconnected.

7. The deep cavity electrolytic machining method according to claim 3, characterized in that: The step of withdrawing the outer cathode and the inner cathode from the workpiece comprises: The machine tool cathode mounting plate is controlled to move so as to retract the outer cathode and the inner cathode from the workpiece.

8. A deep cavity electrolytic machining device, characterized in that: Used to implement the deep cavity electrolytic machining method according to any one of claims 1 to 7; the deep cavity electrolytic machining device comprises an outer cathode, an inner cathode, a DC power supply, a machine tool cathode mounting plate and a cylinder; The outer cathode is sleeved on the outer side of the inner cathode; an inner insulating layer is provided on the inner side of the outer cathode, and an outer insulating layer is provided on the outer side; a channel for electrolyte flow is provided in the middle of the inner cathode; The positive electrode of the DC power supply is connected to the workpiece, the inner cathode is connected to the negative electrode of the DC power supply through an inner cathode switch, and the outer cathode is connected to the negative electrode of the DC power supply through an outer cathode switch; One end of the cylinder is connected to the machine tool cathode mounting plate, and the other end is connected to the outer cathode; the inner cathode is connected to the machine tool cathode mounting plate.

9. The deep cavity electrolytic machining device according to claim 8, characterized in that: The deep cavity electrolytic machining device also includes a liquid collecting chamber, which is arranged between the machine tool cathode mounting plate and the inner cathode and is connected to the channel in the middle of the inner cathode.

10. The deep cavity electrolytic machining device according to claim 9, characterized in that: Pipe joints are respectively arranged on both sides of the liquid collecting chamber, and the pipe joints are used to connect electrolyte tubes.

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