Modular clamping closed-channel electrolytic machining apparatus and method

Abstract

This invention relates to a combined clamping closed-channel electrolytic machining apparatus and method, belonging to the field of special machining technology. The apparatus mainly includes a clamping body, a ring, a workpiece, a cathode rod, and a cathode head. The electrode is fed along a spatial trajectory to achieve machining of the closed-channel component. Traditionally, the blank's inlet and outlet edges are designed to be the same height as the disc. To improve the overall uniformity of the allowance, a uniform allowance groove is designed along the inlet and outlet edges of the workpiece to reduce the allowance. When the cathode exits the channel, its outlet is open, which can lead to insufficient liquid in the machining area and cause a short circuit. Therefore, a conductive metal ring and the workpiece are designed to form a combined component, solving the problem of drastic flow field changes when the cathode exits the channel. The cathode rod is made of conductive metal, and a durable cathode rod insulation method is proposed to eliminate the influence of stray corrosion on the machining process.

Description

Technical Field

[0001] This invention proposes a combined clamping closed-channel electrolytic machining device and method, belonging to the field of special machining technology. Background Technology

[0002] Closed components used in aerospace applications are typically made of difficult-to-machine materials, such as nickel-based superalloys and titanium alloys. Currently, the main machining method for closed components, both domestically and internationally, is CNC milling, which suffers from high tool costs and long machining times. Furthermore, closed components have confined spaces and their contours are extremely distorted three-dimensional surfaces, making it difficult for milling cutters to enter the cavity. Moreover, as the depth of feed increases, the vibration amplitude of the milling cutter head also increases, severely affecting machining quality. Electrolytic machining (EMC) is a typical non-contact machining method. Compared with traditional mechanical cutting methods, EMC has inherent advantages such as no tool wear, low cost, high machining efficiency, and high surface quality.

[0003] Chinese patent CN116117251A proposes a spiral-entry electrolytic machining method and apparatus, in which the cathode extends parallel to the rear end face of the workpiece at the end of the machining process, and an insulating backflow groove is designed.

[0004] Chinese patent CN115781193A proposes a wire cutting technique to create a blade ring channel. First, specific A and C angles are found. Then, wire cutting guide holes are machined on the cavity substrate to be cut. A semi-finished product is obtained through wire cutting technology, and then the semi-finished product is precision machined.

[0005] Chinese patent CN108994402A proposes the use of electrical discharge machining (EDM) to perform rough and fine machining on a closed blade ring. The process mainly consists of two steps: first, the airflow channel is rough machined using EDM, and then the blade ring is finely machined by replacing the electrode.

[0006] Patent CN111008445A proposes a method for determining the tool axis in fixed-axis milling. This method can save the step of manually specifying the tool axis and quickly complete the compilation of CNC programs.

[0007] In summary, although there are many methods for processing closed-loop components, each has its limitations. Currently, the issue of flow field stability when the cathode exits the channel during electrolytic processing of closed-loop components has not been well resolved, thus requiring urgent research. Summary of the Invention

[0008] The purpose of this invention is to provide a combined clamping closed-channel electrolytic machining device and method to effectively solve the problems of uneven machining allowance and flow field stability in closed-channel electrolytic machining.

[0009] A combined clamping closed-channel electrolytic machining device is characterized by comprising a pad, a clamping body, a ring, a connecting guide rod, a transition plate, a cathode rod, a cathode head, a workpiece, and a clamping component; wherein a stop block is provided on the upper part of the clamping body; uniform allowance grooves are provided on both the front and back of the workpiece; the workpiece is located on the front side of the stop block structure, and the bottom surface of the workpiece is connected to the clamping body; the ring is positioned between the back of the workpiece and the stop block structure and is clamped by the clamping component; the front of the workpiece is the initial machining surface; wherein an electrolyte inlet is provided on the connecting guide rod, and an outlet hole is provided at the end; the cathode rod and cathode head are provided with electrolyte channels, and the electrolyte is sprayed out from the slit in the middle of the cathode head; the machine tool shaft is sequentially connected to the connecting guide rod, the transition plate, the cathode rod, and the cathode head; an insulating sleeve is fitted on the surface of the cathode rod.

[0010] The processing method using the aforementioned combined clamping closed-channel electrolytic machining apparatus is characterized by the following processes: a conductive metal ring is tightly fitted with the workpiece to form a combined component, preventing drastic changes in the flow field when the cathode head exits the channel, thus affecting the stability of the processing; a clamping component presses the workpiece and the clamping body together, ensuring the ring is pressed against the workpiece to prevent liquid leakage from the gap; uniform allowance grooves are provided on the front and back of the workpiece to ensure the width of the processed surface is lower than the width of the hub, reducing the allowance difference between the inlet and outlet sides; during processing, an insulating sleeve prevents stray corrosion of the processed channel when the cathode rod enters the processed channel, improving processing accuracy.

[0011] The insulating sleeve is segmented, ensuring insulation even when the cathode rod has uneven curvature and thickness. Each segment of the insulating sleeve has a small gap between itself and the surface of the cathode rod, allowing the rigid insulating sleeve to fit snugly over the cathode rod surface; the gaps between the two are filled with adhesive.

[0012] The advantages of this invention are:

[0013] This invention designs a uniform allowance groove on the workpiece surface. The actual air intake and exhaust edge positions are slightly lower than the upper and lower surfaces of the disc body. Traditional blank air intake and exhaust designs are at the same height as the disc body, resulting in excessive allowance at the air intake and exhaust edges, leading to low forming accuracy. Excessive allowance at the air intake and exhaust edges is detrimental to subsequent finishing. To improve the uniformity of the allowance at the air intake and exhaust edges, a groove structure is designed on the blank according to the shape of the air intake and exhaust edges, thereby improving the uniformity of the allowance at the air intake and exhaust edges. The amount of recess in the uniform allowance groove is determined by the allowance after blade machining, ensuring that the allowance at the air intake and exhaust edges of the blade is the same as the allowance on the blade base and blade back.

[0014] This invention designs a metal ring with one end face tightly against the workpiece and the other end face embedded in a clamping body. The ring's thickness is primarily determined by the machining stroke, ensuring it is not machined through, thus guaranteeing the stability of the flow field during machining. This method achieves stable machining even when the workpiece is machined through, improving stability. The device is simple, highly consistent, and effectively prevents abrupt changes in the flow field during machining, further enhancing process stability. To prevent liquid leakage from the contact surface between the ring and the workpiece, the ring and workpiece are tightly connected, ensuring no gaps between them.

[0015] During processing, the cathode rod needs to enter the pre-processed channel. Due to the narrowness of the channel, the cathode head cannot be directly connected to the wire; conductivity is achieved through the cathode rod, which is therefore made of conductive metal. The conductivity of the cathode rod causes stray corrosion to the sidewalls of the pre-processed channel, severely affecting processing accuracy. Therefore, the surface of the cathode rod is insulated. Traditional adhesive insulation methods have extremely poor stability; the insulation layer breaks down after processing just one channel, leading to poor experimental repeatability. Therefore, it is proposed to add an insulating sleeve to the cathode rod. Insulating sleeves can be flexible or rigid. Due to the high electrolyte pressure, flexible insulating sleeves are easily broken; therefore, a rigid insulating sleeve is used. Because the cathode rod is curved with varying curvature at different locations, a single, integral insulating sleeve cannot be installed. Therefore, it is proposed to segment the insulating sleeve, leaving a small gap between the sleeve and the cathode rod to allow it to be installed onto the cathode. After installation, the gap between the cathode rod and the insulating sleeve is filled with adhesive. Initially, the insulation method was a semi-insulated cathode rod, only insulating the part of the cathode rod entering the channel. This method requires high rigidity of the insulating sleeve; otherwise, with prolonged use, the insulating sleeve will be deformed by the electrolyte, causing it to shift towards uninsulated areas. This results in uninsulated portions of the cathode rod within the channel, affecting manufacturing accuracy. To address this issue, the insulating sleeve was improved by using a fully insulating sleeve that completely encloses the cathode rod. The length of the insulating sleeve is greater than the length of the cathode rod, allowing excess material to be removed after installation, ensuring no gaps between the sleeve sections and thus reducing stray corrosion.

[0016] In this patent, the shape of the cathode rod also affects the flow field. Ideally, the cathode rod should be centered in the processed channel at any given moment during processing, ensuring uniform flow resistance across all parts and thus guaranteeing a homogeneous flow field. However, the curvature of the actual processing trajectory is irregular, making it difficult to guarantee that the cathode rod is always centered within the processing channel. Therefore, based on the initial shape of the cathode rod using the processing trajectory shape, the distance from the sidewall of the cathode rod to the processed channel at different times is analyzed to ensure that the cathode rod is as centered as possible within the channel. This process corrects the shape of the cathode rod, ultimately resulting in an optimized cathode rod that improves flow field stability. Attached Figure Description

[0017] Figure 1 A schematic diagram of a combined clamping closed-channel electrolytic machining device and method for components.

[0018] Figure 2 This is a schematic diagram of the coupling and guide rod structure;

[0019] Figure 3 This is a schematic diagram of the cathode rod and insulating layer;

[0020] Figure 4 Partial schematic diagram of the workpiece allowance uniform groove;

[0021] Figure 5 Schematic diagram showing the positions of the closed component and the ring;

[0022] The labels in the diagram are as follows: 1-pad, 2-clamp body, 3-ring, 4-coupling and guide rod, 5-adapter plate, 6-cathode rod, 6-1-semi-insulating sleeve, 6-2-fully-insulating sleeve, 7-cathode head, 8-workpiece, 9-clamping component, 10-closed component, 4-1-connecting machine tool hole, 4-2-inlet hole, 4-3-outlet hole, 8-1-balance uniform tank. Implementation

[0023] The working method of the present invention will be further explained below with reference to the accompanying drawings:

[0024] The specific experimental steps of this invention are as follows:

[0025] (1) First, clamp the pad, clamp body, connecting shaft and guide rod, adapter plate, cathode rod and cathode head onto the machine tool;

[0026] (2) Mount the ring and workpiece onto the fixture, use the clamping parts to clamp the workpiece, and finally press the ring onto the surface of the workpiece.

[0027] (3) Connect the electrolyte pipeline and connect the positive terminal of the processing power supply to the workpiece and the negative terminal to the cathode;

[0028] (4) Start the CNC machine tool, set the tool, and find the initial machining position;

[0029] (5) After confirming that the feed program and initial position are correct, start the electrolyte circulation system and the processing power supply;

[0030] (6) Start the feed program and begin machining;

[0031] (7) After the channel is processed, stop the power supply and circulation system, return to the initial processing position through the retraction program, adjust the workpiece position to enter the next station, and repeat step (5) until all channels are processed.

[0032] (8) After processing, turn off the power and circulation system, and move the electrode to a safe position.

Claims

1. A combined clamping closed-channel electrolytic machining device for components, characterized in that: Includes a pad (1), a clamping body (2), a ring (3), a connecting guide rod (4), a transition plate (5), a cathode rod (6), a cathode head (7), a workpiece (8), and a clamping component (9); The clamping body (2) is provided with a stop block on the upper part; the workpiece (8) is provided with a uniform allowance groove (8-1) on both the front and back sides; the workpiece (8) is located on the front side of the stop block structure, and the bottom surface of the workpiece is connected to the clamping body (2); the ring (3) is set between the back side of the workpiece and the stop block structure, and is clamped by the clamping part (9); the front side of the workpiece (8) is the initial machining surface; The connecting guide rod (4) is provided with an electrolyte inlet (4-2) and an outlet hole (4-3) at its end; the cathode rod (6) and cathode head (7) are provided with electrolyte channels, and the electrolyte is sprayed out from the slit in the middle of the cathode head; the machine tool shaft is connected in sequence to the connecting guide rod (4), the adapter plate (5), the cathode rod (6), and the cathode head (7); the cathode rod (6) is covered with an insulating sleeve (6-2).

2. The combined clamping closed-type component channel electrolytic machining apparatus according to claim 1, characterized in that: The aforementioned insulating sleeve (6-2) has a segmented structure, with each segment having a small gap from the surface of the cathode rod, which is filled with glue.

3. The processing method using the combined clamping closed-type component channel electrolytic machining apparatus as described in claim 1, characterized in that... Includes the following processes: The conductive metal ring (3) and the workpiece (8) are closely fitted to form a combined component, so as to avoid the flow field from changing drastically when the cathode head (7) comes out of the channel, thus affecting the stability of the processing process; The clamping component (9) clamps the workpiece (8) to the clamp body (2), so that the ring (3) is pressed against the workpiece (8) to prevent liquid from leaking from the gap; The workpiece (8) has uniform allowance grooves (8-1) on the front and back sides to ensure that the width of the machined surface is lower than the width of the wheel hub, thereby reducing the allowance difference between the intake and exhaust sides; During the processing, the insulating sleeve (6-2) prevents stray corrosion of the processed channel when the cathode rod enters the processed channel, thereby improving the processing accuracy.

4. The processing method of the combined clamping closed-type component channel electrolytic machining device according to claim 3, characterized in that... Includes the following processes: During the processing, the initial shape of the cathode rod is based on the shape of the processing trajectory. By analyzing the distance from the sidewall of the cathode rod to the processed channel at different times, the cathode rod is kept as close to the center of the channel as possible. This process corrects the shape of the cathode rod, ultimately resulting in an optimized cathode rod.

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