An electrolytic machining electrode and method for shielding the inner cavity of a propeller hub arm with variable diameter.
By designing multiple electrolyte chambers in the electrolytic machining electrode and connecting them to the main liquid supply pipeline, the machining accuracy and strength problems of the inner cavity of the variable diameter propeller arm were solved, achieving efficient and uniform electrolytic machining results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AVIC BEIJING AERONAUTICAL MFG TECH RES INST
- Filing Date
- 2023-12-12
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies are insufficient for efficiently machining the variable-diameter shielded inner cavity of helicopter rotor hub arms, leading to inconsistent machining accuracy and reduced strength.
An electrochemical machining electrode with multiple isolated electrolyte chambers is connected to each electrolyte chamber through a main electrolyte supply pipe, achieving a balanced distribution of electrolyte pressure and flow rate, and ensuring uniform machining in different spatial domains.
This improved the machining accuracy and strength of the inner cavity of the propeller hub support arm, avoided problems such as tool marks and inconsistent surface finish, and improved machining efficiency and strength.
Smart Images
Figure CN117600584B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemical machining technology, specifically to an electrochemical machining electrode and method for shielding the inner cavity of a rotor hub support arm with variable diameter. Background Technology
[0002] During vertical takeoff and landing, flight, and hovering, helicopters frequently use the central rotor hub to drive the blades to change angles and achieve various flight maneuvers. The rotor hub arm, as a key component of the three driving hinges (pitch hinge, flaring hinge, and flapping hinge) between the rotor hub and blades, is a crucial load-bearing component, needing to withstand complex loads such as centrifugal force, flapping moment, and flaring moment transmitted from the blades. Simultaneously, the rotor hub arm must also withstand atmospheric turbulence and vibration loads from the engine and transmission system. The rotor hub arm exhibits a complex structure, often featuring variable cross-section cavities with interference characteristics, and is made of high-performance, difficult-to-machine titanium alloys, requiring excellent surface integrity to withstand high-intensity variable load impacts.
[0003] The propeller hub support arm is rod-shaped, with small openings at both ends and a large space in the middle to conceal the internal cavity, achieving weight reduction while meeting strength requirements. Figure 1 As shown.
[0004] Currently, the machining of such components with shielded internal cavities mainly employs specialized horizontal boring machines. However, due to the small opening, large bore diameter, and long axial dimension, the boring process is limited. This limitation manifests primarily in the following ways: machining both ends of the excessively long workpiece inevitably results in tool marks and inconsistent surface finish; boring with an extended tool holder causes tool tip vibration, reduced depth of cut, and low efficiency. Furthermore, to achieve boring, the inlet hole size cannot be designed too small, which to some extent reduces the strength of the propeller hub support arm.
[0005] Therefore, the inventors provide an electrolytic machining electrode and method for shielding the inner cavity of a rotor hub arm with variable diameter. Summary of the Invention
[0006] (1) Technical problems to be solved
[0007] This invention provides an electrolytic machining electrode and method for shielding the inner cavity of a rotor hub arm with variable diameter, which solves the technical problem that affects the accuracy of the inner cavity of the rotor hub arm due to the inconsistent gap between the electrode and the workpiece at the beginning of the machining process.
[0008] (2) Technical solution
[0009] A first aspect of the present invention provides an electrolytic machining electrode for a variable diameter shielding cavity of a propeller hub arm, comprising an electrode body and a plurality of mutually isolated electrolyte chambers located within the electrode body, each of the electrolyte chambers being individually connected to a main supply pipe and having its machining flow field homogenized through the main supply pipe.
[0010] Furthermore, the electrode body is a single-edged electrode.
[0011] Furthermore, the number of electrolyte chambers is at least three.
[0012] Furthermore, the machining profile of the electrode body is a variable diameter surface.
[0013] Furthermore, the middle straight section and the two ends of the electrode body both have electrolyte chambers.
[0014] Furthermore, the main liquid supply pipeline is connected to each of the electrolyte chambers through corresponding interfaces.
[0015] A second aspect of the present invention provides an electrolytic machining method for concealing the inner cavity of a variable diameter propeller hub arm, comprising the following steps:
[0016] Electrolytic machining is performed by inserting the electrolytic machining electrode into the variable diameter shielded inner cavity of the propeller hub support arm.
[0017] The electrolyte in each electrolyte chamber is regulated from the inlet end using the main liquid supply pipeline, so that the electrolyte pressure / flow rate in the processing area is balanced in different time and space domains.
[0018] Furthermore, the step of extending the electrolytic machining electrode into the variable-diameter shielded cavity of the propeller hub support arm for electrolytic machining specifically includes:
[0019] In the first stage, the gap between the electrode surface and the inner cavity of the workpiece is greater than the preset value, and the electrolyte flows out freely.
[0020] In the second stage, the straight middle section of the electrolytic machining electrode is in contact with the inner cavity of the workpiece, and the gap between the large curvature section of the electrolytic machining electrode and the inner cavity of the test piece is greater than the preset value, allowing the electrolyte to flow out freely.
[0021] In the third stage, both the straight and large curvature sections of the electrolytic machining electrode are machined. The machining gap between each position point on the machining surface of the electrolytic machining electrode and its corresponding workpiece cavity is the same, and the electrolyte pressure is consistent.
[0022] Furthermore, the second stage is the stage in which the inner cavity of the workpiece is in a state of large-scale material removal by electrode follow-up feeding.
[0023] Furthermore, the third stage is the stage in which the inner cavity of the workpiece is precisely machined to the final shape using dual Z-axis synchronous feed.
[0024] (3) Beneficial effects
[0025] In summary, this invention divides the inner cavity of the processing electrode into multiple separate electrolyte chambers, separating the electrolyte distribution in the flat state and the large curvature state of the electrode, ensuring uniform electrolyte distribution in each region and adapting to different spatiotemporal requirements; at the same time, each electrolyte chamber of the processing electrode is individually connected to the main electrolyte supply pipe, and the electrolyte is actively regulated from the inlet end, so that the electrolyte pressure or flow rate in the processing area is balanced in different spatiotemporal domains, and the processing flow field is homogenized. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a structural schematic diagram of an existing helicopter rotor hub support arm;
[0028] Figure 2 This is a schematic diagram of the structure of an electrolytic machining electrode for shielding the inner cavity of a variable diameter propeller arm, provided by an embodiment of the present invention.
[0029] Figure 3 This is a schematic diagram of the structure of an electrolytic machining electrode and a main liquid supply pipeline provided in an embodiment of the present invention;
[0030] Figure 4 This is a schematic flowchart of an electrolytic machining method for shielding the inner cavity of a variable diameter propeller arm, provided in an embodiment of the present invention.
[0031] In the picture:
[0032] 1-Electrode body; 101-Electrolyte chamber; 102-Inlet; 2-Main supply pipe; 201-Interface; 3-Workpiece. Detailed Implementation
[0033] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.
[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0035] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0036] Figure 2 This is a schematic diagram of the structure of an electrolytic machining electrode for shielding the inner cavity of a variable diameter propeller arm, as provided in an embodiment of the present invention. Figure 2-3 As shown, the electrolytic processing electrode includes an electrode body 1 and multiple mutually isolated electrolyte chambers 101 located within the electrode body 1. Each electrolyte chamber 101 is individually connected to the main liquid supply pipe 2 and the processing flow field is homogenized through the main liquid supply pipe 2.
[0037] In the above embodiment, during electrolytic machining of a deep, elongated, shielded, variable-diameter internal cavity, the electrolyte flows forward through the internal cavity of the electrode to the machining gap between the electrode and the workpiece. Initially, the electrode surface and the cylindrical surface of the workpiece cannot completely fit together, resulting in inconsistent machining gaps and electrolyte flow. Consequently, a large amount of electrolyte will overflow from the area with the largest gap and lowest pressure. In this case, it is advisable to divide the internal electrohydraulic cavity of the electrode into separate chambers, allowing the electrolyte in each chamber to flow out independently without affecting each other. For example... Figure 2 As shown, the same electrolyte outflow pressure is present in both the small gap region between the electrode and the specimen and the large gap region between the electrode and the specimen's inner cavity, ensuring uniform electrolyte distribution across the processing area. To address the issue of inconsistent electrolyte pressure caused by the electrode profile not fully fitting the workpiece's cylindrical profile during initial processing, the internal chamber of the electrode was partitioned to form multiple independent electrolyte supply chambers. Simultaneously, as... Figure 3 As shown, the inlet 102 of each electrolyte chamber 101 of the electrode is connected to the main supply pipe 2 through the corresponding interface 201. The electrolyte is actively regulated from the inlet end, so that the electrolyte pressure or flow rate in the processing area is balanced in different time and space domains, and the processing flow field is homogenized.
[0038] As an optional implementation, the electrode body 1 is a single-edged electrode. Since the electrode body 1 rotates within the cavity of the workpiece 3 under the drive of an external drive mechanism during processing, designing it as a single-edged electrode is sufficient to meet the processing requirements.
[0039] As an optional implementation, the number of electrolyte chambers 101 is at least three. The specific number of electrolyte chambers 101 is not limited and can be set according to actual needs, but generally should not exceed five, as a larger number would increase processing difficulty.
[0040] As an optional implementation, the machining profile of the electrode body 1 is a variable diameter surface. This design of the electrode body 1 is intended to adapt to the final shape of the workpiece's inner cavity.
[0041] As an optional implementation method, such as Figure 2 As shown, the straight section in the middle and the high-curvature sections at both ends of the electrode body 1 both have electrolyte chambers 101. Separating the straight state and the high-curvature state of the electrode ensures that the electrolyte is evenly distributed in each region.
[0042] Figure 4 This is a schematic flowchart of an electrolytic machining method for concealing the inner cavity of a variable-diameter propeller hub arm according to an embodiment of the present invention. Figure 4 As shown, the method may include the following steps:
[0043] S100. Electrolytic machining is performed by inserting the electrolytic machining electrode into the variable diameter shielded cavity of the propeller hub support arm.
[0044] S200: The electrolyte in each electrolyte chamber is regulated from the inlet end using the main liquid supply pipeline, so that the electrolyte pressure / flow rate in the processing area is balanced in different time and space domains.
[0045] As an optional implementation, in step S200, the electrolytic machining electrode is inserted into the variable-diameter shielded cavity of the propeller hub support arm for electrolytic machining, specifically including:
[0046] In the first stage, the gap between the electrode surface and the inner cavity of the workpiece is greater than the preset value, and the electrolyte flows out freely.
[0047] In the second stage, the straight middle section of the electrolytic machining electrode fits into the inner cavity of the workpiece, and the gap between the large curvature section of the electrolytic machining electrode and the inner cavity of the test piece is greater than the preset value, allowing the electrolyte to flow out freely.
[0048] In the third stage, both the straight and large curvature sections of the electrolytic machining electrode are machined. The machining gap between each position point on the machining surface of the electrolytic machining electrode and its corresponding workpiece cavity is the same, and the electrolyte pressure is consistent.
[0049] In the above embodiments, at the beginning of the long shielded variable diameter inner cavity electrolytic machining (first stage): the gap between the electrode profile and the inner cavity of the workpiece is large, the electrolyte flows out uniformly and freely, and there is no pressure difference. At this time, the electrolyte flow is evenly distributed.
[0050] The deep, shielded inner cavity electrolysis enters the initial stable stage (second stage): the middle straight section of the electrode fits snugly against the inner cavity of the workpiece (cylindrical surface), forming a small machining gap, resulting in relatively large flow resistance for the electrolyte; the large curvature section of the electrode has a large gap with the inner cavity of the specimen, allowing the electrolyte to flow out freely. Although the flow resistance differs between the straight and large curvature sections, it does not affect the machining results. In the straight section, the electrolyte is supplied to all three chambers independently, resulting in uniform electrolyte flow and stable electrolyte machining, with material removal from the specimen. In the large curvature section, there is no pressure on the electrolyte outflow; at this point, the electrode is far from the surface of the inner cavity of the specimen, and the machining amount is very small. At this stage, the deep, shielded inner cavity is in the stage of large-scale material removal by electrode follow-up feed.
[0051] As electrolytic machining progresses, the deep, elongated, shielded inner cavity enters a stable phase (stage three): both the straight and large curvature sections of the electrode are processed, the gap between the cross-section electrode and the inner cavity of the specimen is consistent, the wetted circumference radius of the electrolyte supply pipes in each electrolyte chamber is consistent, and the electrolyte pressure is consistent. The electrolyte flows uniformly in the straight and large curvature sections of the electrode, and machining proceeds stably. At this point, the deep, elongated, shielded inner cavity is in the final stage of precise machining using dual Z-axis synchronous feed.
[0052] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.
[0053] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.
Claims
1. An electrolytic machining method for concealing the inner cavity of a variable-diameter propeller hub arm, characterized in that, The electrolytic processing electrode includes an electrode body (1) and a plurality of mutually isolated electrolyte chambers (101) located within the electrode body (1). Each electrolyte chamber (101) is individually connected to a main liquid supply pipe (2) and the processing flow field is homogenized through the main liquid supply pipe (2). The method includes the following steps: Electrolytic machining electrodes are inserted into the variable-diameter shielded cavity of the propeller hub arm for electrolytic machining. The electrolyte in each electrolyte chamber is regulated from the inlet end using the main liquid supply pipeline, so that the electrolyte pressure / flow rate in the processing area is balanced in different time and space domains; The process of extending the electrolytic machining electrode into the variable-diameter shielded cavity of the propeller hub arm for electrolytic machining specifically includes: In the first stage, the gap between the electrode surface and the inner cavity of the workpiece is greater than the preset value, and the electrolyte flows out freely. In the second stage, the straight middle section of the electrolytic machining electrode is in contact with the inner cavity of the workpiece, and the gap between the large curvature section of the electrolytic machining electrode and the inner cavity of the test piece is greater than the preset value, allowing the electrolyte to flow out freely. In the third stage, both the straight and large curvature sections of the electrolytic machining electrode are machined. The machining gap between each position point on the machining surface of the electrolytic machining electrode and its corresponding workpiece cavity is the same, and the electrolyte pressure is consistent.
2. The electrolytic machining method according to claim 1, characterized in that, The second stage is when the workpiece cavity is in a stage of large-scale material removal by electrode follow-up feeding.
3. The electrolytic machining method according to claim 1, characterized in that, The third stage is the stage in which the inner cavity of the workpiece is precisely machined to its final shape using dual Z-axis synchronous feed.
4. The electrolytic machining method according to claim 1, characterized in that, The electrode body (1) is a single-edged electrode.
5. The electrolytic machining method according to claim 1, characterized in that, The number of electrolyte chambers (101) is at least three.
6. The electrolytic machining method according to claim 1, characterized in that, The machining surface of the electrode body (1) is a variable diameter surface.
7. The electrolytic machining method according to claim 6, characterized in that, The electrode body (1) has an electrolyte cavity (101) in the middle straight section and the two ends with large curvature sections.
8. The electrolytic machining method according to any one of claims 1-7, characterized in that, The main liquid supply pipeline (2) is connected to each of the electrolyte chambers (101) through the corresponding interface (201).