Precise electrolytic machining method for herringbone groove microstructure of air flotation kinematic pair

Abstract

The invention discloses a precise electrolytic machining method for a herringbone groove microstructure of an air floatation kinematic pair, which comprises the following steps: machining a workpiece by adopting a profiling cathode with a convex structure complementary with a target herringbone groove on the surface, and connecting the workpiece with an anode assembly; the convex structure is a processing area, and an insulating coating is arranged on the surface of a non-processing area except the convex structure; the processing pulse of the power supply system is started at the liquid supply closing stage of the electrolyte system, and the processing pulse of the power supply system is stopped and the electrolyte is updated at the liquid supply opening stage of the electrolyte system. High-precision, low-cost and high-efficiency machining of the herringbone groove microstructure is achieved through profiling cathode shaping, group pulse precise etching and intermittent liquid supply and deslagging, and the problems of stray corrosion control, groove depth gradual change uniformity and batch consistency in electrolytic machining are solved.

Description

Technical Field

[0001] The invention relates to the technical field of special processing, and in particular to a precision electrolytic processing method for a herringbone groove microstructure of an air-floating motion pair. Background Art

[0002] With the rapid development of industries such as aerospace, semiconductors, automotive manufacturing, and biomedicine, their equipment and key components are increasingly moving towards high precision, high temperature resistance, and miniaturization. Simultaneously, a large number of parts with microfeatures such as micropores and microgrooves have been designed and developed. These microfeatures enable these components to possess excellent mechanical and mechanical properties. In some precision rotating equipment, air bearings with herringbone microgrooves on their surfaces can significantly improve the stability of rotating machinery. However, machining these microstructures is currently primarily performed using machining methods such as mechanical machining and laser processing. Traditional mechanical machining suffers from low precision, inefficiency, and significant material waste, making it unsuitable for precision machining of microstructures. Compared to mechanical machining, laser machining offers advantages such as high precision and stress-free processing. However, laser machining also suffers from lower efficiency, poor surface quality in the processed area, and severe burns. Therefore, machining these microfeatures is a challenging and hot topic. Traditional machining and laser machining alone have difficulty meeting the required precision and surface quality, creating new demands for the manufacturing of these key components.

[0003] Electrochemical machining (ECM) is a specialized machining technology that removes material based on the principle of electrochemical anodic dissolution. It offers advantages such as zero tool electrode loss, high machining efficiency, excellent surface quality, and no limitations on the strength, hardness, or toughness of the material being machined. It is suitable for the precise and efficient manufacturing of microstructures in certain components. For parts with the aforementioned herringbone microstructure, ECM offers unique advantages. Theoretically, ECM can achieve machining accuracy at the ionic scale. Its inherent advantages, such as high machining efficiency and excellent surface quality, make it suitable for the precise and efficient manufacturing of microstructures. Summary of the Invention

[0004] The purpose of the present invention is to provide a precision electrolytic machining method for air-floating motion herringbone groove microstructures to solve the defects of existing traditional mechanical machining and laser machining technologies such as low machining efficiency, low dimensional accuracy, poor surface quality and severe burns.

[0005] To achieve the above-mentioned purpose, the present invention provides a technical solution: a precision electrochemical machining method for the herringbone groove microstructure of an air-floating motion pair:

[0006] A contoured cathode with a convex structure on its surface complementary to the target herringbone groove is used to process a workpiece, which is connected to an anode assembly. The convex structure is the processing area, and an insulating coating is provided on the surface of the non-processing area outside the convex structure.

[0007] An electrolyte system intermittently supplies an acidic electrolyte to the machining gap; a contoured cathode and a workpiece are charged by a power supply system; and during machining, the intermittent supply of electrolyte by the electrolyte system is synchronized with the pulse action of the power supply system: the machining pulse of the power supply system is started during the liquid supply closing phase of the electrolyte system, and the machining pulse of the power supply system is stopped and the electrolyte is refreshed during the liquid supply opening phase of the electrolyte system.

[0008] To optimize the above technical solutions, specific measures taken also include:

[0009] In the electrolyte system, electrolyte is intermittently supplied to the processing gap through a bidirectional side-flow flow field liquid cavity, and the bidirectional side-flow flow field liquid cavity includes a liquid storage cavity and a circumferential array guide channel. The electrolyte is diverted from the inlet to the opposite direction and flows through the processing gap.

[0010] The liquid supply closing phase corresponds to the pulse width phase of the power supply system, and the liquid supply opening phase corresponds to the pulse interval phase of the power supply system.

[0011] Furthermore, the power supply system is powered by a high-frequency group pulse power supply, which is composed of a high-frequency main pulse and a low-frequency modulation pulse to form a group pulse output in a unit cycle.

[0012] The pH value of the electrolyte is 3-6, and the components include sodium nitrate and sodium citrate.

[0013] Furthermore, a suspended stationary processing mode is adopted, so that the contour cathode and the workpiece are relatively stationary and concentric during processing, forming a uniform processing gap.

[0014] The electrolyte renewal mentioned above refers to flushing the electrolyte into the machining gap, removing the electrolysis products accumulated in the machining area, renewing the electrolyte in the machining gap, and restoring its concentration and conductivity.

[0015] Furthermore, the size of the protruding structure in the processing area of the contoured cathode surface is designed for reverse compensation according to the processing gap.

[0016] The power supply system includes a power supply anode and a power supply cathode, the power supply anode is connected to the anode assembly, and the power supply cathode is connected to the cathode assembly; the electrolyte system includes an inlet pipe and an outlet pipe, the cathode assembly has an inlet and an outlet, the inlet pipe is connected to the inlet of the cathode assembly, and the outlet pipe is connected to the outlet of the cathode assembly.

[0017] Furthermore, the process of electrochemical machining includes the following steps:

[0018] Step S1, assembling a cathode assembly and an anode assembly, wherein the cathode assembly is a contoured cathode;

[0019] Step S2, installing and fixing the cathode assembly and the anode assembly, and adjusting the positions of the cathode assembly, the anode assembly and the workpiece, detecting the axis offset of the workpiece relative to the cathode assembly in real time, and controlling the concentricity deviation of the workpiece to be within a specified range;

[0020] Step S3, connecting the power anode of the power system to the anode assembly to make the workpiece positively charged, and connecting the power cathode of the power system to the cathode assembly to make the cathode assembly negatively charged;

[0021] Step S4, connecting the liquid inlet pipe of the electrolyte system to the liquid inlet of the cathode assembly, and connecting the liquid outlet pipe to the liquid outlet of the cathode assembly;

[0022] Step S5, opening the electrolyte system, allowing the electrolyte to flow through the machining gap between the cathode assembly and the workpiece, and checking the sealing condition;

[0023] Step S6, perform short circuit detection; then set power parameters, turn on the power system and start electrolytic machining.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention adopts an intermittent liquid supply method. The advantage is that it significantly improves the flow state of the electrolyte, product discharge and heat transfer process in the narrow processing gap through periodic pressure fluctuations, thereby overcoming the inherent limitations of continuous liquid supply (such as cavitation, product retention, and uneven heat dissipation), and ultimately achieves higher processing accuracy, better surface quality, stronger process stability and reliability, and is particularly suitable for the processing of high-precision, complex surface parts.

[0026] 2. The power supply system and electrolyte system of the present invention have a coordinated pulse mechanism, which significantly improves the flow state of the electrolyte, product discharge and heat transfer process in the narrow processing gap, thereby overcoming the inherent limitations of continuous liquid supply.

[0027] 3. For the microstructure of the herringbone groove of the air-floating motion, electrolytic machining technology is used. This method removes material in the form of ions and is not limited by the performance of the workpiece material. It can process various difficult-to-cut metal materials, and there is no mechanical cutting force on the workpiece surface, so the workpiece surface will not produce residual stress and deformation caused by this.

[0028] 4. The present invention uses a high-frequency group pulse power supply to modulate the high-frequency main pulse into a group pulse output, which can not only suppress stray corrosion in the non-processing area, but also effectively remove the electrolysis products in the pulse gap, improve the processing flow field, and improve the processability and precision of electrolytic processing.

[0029] 5. This invention enables the integrated processing of bearing parts featuring radial and internal grooves. Compared to traditional machining and laser processing, it can process the entire workpiece in a single operation. During processing, the tool cathode and workpiece anode remain separate, maintaining a defined machining gap. This eliminates any wear on the tool cathode, allowing for long-term, multiple-use applications. High processing efficiency significantly reduces batch production costs and improves the efficiency of processing microstructures in air-bearing motion herringbone grooves. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a simplified schematic diagram of the electrolytic machining system of the present invention.

[0031] Figure 2 This is a schematic diagram of a workpiece whose processing feature is a groove in the inner hole of a bearing.

[0032] Figure 3 This is a schematic diagram of a workpiece having a bearing radial groove as a processing feature according to the present invention.

[0033] Figure 4 This is a schematic diagram of the high-frequency group pulse of the power supply of the present invention.

[0034] Figure 5 It is a schematic diagram of the coordinated output form of the power supply and electrolyte pulse of the present invention.

[0035] Figure 1 In: 1. Power supply system; 2. Cathode assembly; 3. Anode assembly; 4. Pulsating pump; 5. Electrolyte filtration system; 6. Electrolytic cell. DETAILED DESCRIPTION

[0036] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0037] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the reagents, methods and equipment used are conventional reagents, methods and equipment in the art unless otherwise specified.

[0038] The invention provides a precision electrolytic machining method for a herringbone groove microstructure of an air-floating motion pair.

[0039] A contoured cathode with a raised structure on the surface complementary to the target herringbone groove is used to process the workpiece, ensuring that the geometric parameters of the electrolytic reaction area and the herringbone pattern are accurately matched, and the workpiece is connected to the anode assembly; the raised structure is the processing area, and an insulating coating is provided on the surface of the non-processing area outside the raised structure.

[0040] Preferably, the size of the protruding structure in the processing area of the contoured cathode surface is designed for reverse compensation according to the processing gap.

[0041] In some embodiments, this method utilizes a hovering, stationary machining mode, keeping the contoured cathode and workpiece relatively stationary and concentric during machining, creating a uniform machining gap. The machining accuracy of the herringbone groove microstructure is ensured by precisely controlling the hovering time and machining current. This allows for micron-level machining of workpiece dimensions and contours, significantly improving dimensional accuracy.

[0042] Preferably, the insulating coating has the characteristics of being firm, dense, and resistant to high-voltage electrolyte erosion and temperature changes, so as to constrain the current to act only in the processing area, improve the localization of processing, prevent stray current from corroding adjacent areas, and ensure that the edges of the herringbone grooves are clear and sharp.

[0043] In this method, the power supply system includes a power supply anode and a power supply cathode, the power supply anode is connected to the anode assembly, and the power supply cathode is connected to the cathode assembly; the electrolyte system includes a liquid inlet pipe and a liquid outlet pipe, the cathode assembly has a liquid inlet and a liquid outlet, the liquid inlet pipe is connected to the liquid inlet of the cathode assembly, and the liquid outlet pipe is connected to the liquid outlet of the cathode assembly.

[0044] In some embodiments, the power supply system is powered by a high-frequency group pulse power supply, which is composed of a high-frequency main pulse and a low-frequency modulation pulse to form a group pulse output within a unit cycle.

[0045] The high-frequency main pulse has a frequency of megahertz; the low-frequency modulating pulse has a frequency of several hundred to several thousand hertz. The high-frequency main pulse and the low-frequency modulating pulse are combined in the following manner: when the low-frequency modulating pulse is high, the high-frequency main pulse outputs a high level; when the low-frequency modulating pulse is low, the high-frequency main pulse outputs a low level. This results in a group pulse output within a unit cycle. The high-frequency group pulses can improve the localization of electrochemical machining. During the intervals between group pulses, electrolysis products are effectively removed, improving the flow field state in the machining gap and enhancing the processability and precision of electrochemical machining.

[0046] An electrolyte system intermittently supplies an acidic electrolyte to the machining gap; a contoured cathode and a workpiece are charged by a power supply system; and during machining, the intermittent supply of electrolyte by the electrolyte system is synchronized with the pulse action of the power supply system: the machining pulse of the power supply system is started during the liquid supply closing phase of the electrolyte system, and the machining pulse of the power supply system is stopped and the electrolyte is refreshed during the liquid supply opening phase of the electrolyte system.

[0047] Preferably, intermittent liquid supply means that the electrolyte flow rate varies periodically at a specific frequency (several hertz to hundreds of hertz), causing the electrolyte in the processing gap to form an alternating flow state of high pressure, low pressure, and high pressure. Intermittent flow flushing significantly improves the discharge efficiency of electrolysis products and the stability of the electrochemical environment in the processing area by dynamically changing the flow field state within the processing gap.

[0048] The liquid supply closing stage corresponds to the pulse width stage of the power supply system, and the liquid supply opening stage corresponds to the pulse interval stage of the power supply system.

[0049] In some embodiments, the pH value of the electrolyte is 3 to 6, and the electrolyte components mainly include sodium nitrate and sodium citrate. The acidic electrolyte can inhibit stray corrosion on the workpiece surface, thin the passivation film on the workpiece surface, and help increase the machining current density.

[0050] In some embodiments, refreshing the electrolyte refers to allowing the electrolyte to flow into the machining gap, clearing electrolysis products accumulated in the machining area, refreshing the electrolyte in the machining gap, and restoring its concentration and conductivity.

[0051] In the electrolyte system, electrolyte is intermittently supplied to the processing gap through a bidirectional side-flow flow field liquid cavity, which includes a liquid storage cavity and a circumferential array guide channel; the electrolyte is diverted from the inlet to the opposite direction and flows through the processing gap.

[0052] In some embodiments, the liquid cavity adopts a multi-inlet design, with a liquid storage cavity and a circular array of guide channels inside, forming a bidirectional lateral flow field; after the electrolyte is introduced into the liquid cavity, it is divided into two streams, flowing through the processing gap in two opposite directions, and then flowing out from the outlets at both ends respectively, and the lateral flow energy can better cover the entire processing surface; the liquid storage cavity is used to stabilize the flow state of the electrolyte, and the guide channel is used to ensure that the flow velocity and pressure in the processing gap are evenly distributed, avoiding dead zones or high-speed flushing zones, so as to achieve the most uniform possible flow velocity and pressure distribution in the entire processing area, and ensure uniform material removal.

[0053] like Figure 1 As shown, in some embodiments, the process of electrochemical machining includes the following steps:

[0054] Step 1: Assemble the cathode and anode parts to form cathode assembly 2 and anode assembly 3, completing the preparation of the tooling;

[0055] Step 2: Fix the cathode assembly 2 to the machine tool's moving spindle and the anode assembly 3 to the machine tool platform. Use dedicated calibration equipment to adjust the position of the cathode and workpiece, and detect the axis offset between the spindle and workpiece in real time. By adjusting the workpiece fixture or spindle position, gradually eliminate the deviation and control the concentricity deviation between the spindle and workpiece within the required range.

[0056] Step 3: Connect the power supply anode to the tooling anode assembly 3 with bolts to make the workpiece positively charged; connect the power supply cathode to the tooling upper cathode assembly 2 with bolts to make the contoured cathode negatively charged;

[0057] Step 4: Connect the liquid inlet pipe to the liquid inlet of the cathode assembly 2, and connect the liquid outlet pipe to the liquid outlet on the cathode assembly 2;

[0058] Step 5: Prepare an acidic electrolyte consisting of sodium nitrate and sodium citrate to a pH between 3 and 6. Start the pulsating pump 4 and electrolyte filtration system 5, allowing the electrolyte to flow steadily through the liquid passage cavity and evenly through the gap between the contoured cathode and the workpiece. Check the sealing condition. The electrolyte flows out of the liquid outlet into the electrolytic cell 6 and then into the electrolyte filtration system 5 for filtration and recycling.

[0059] Step 6: Perform short circuit detection on the tooling, set power parameters, and turn on power supply 1 to start electrolytic machining;

[0060] Step seven, completing the processing within the specified time, turning off the power supply 1 and the electrolyte filtration system 5, and completing the precision electrolytic processing of the air-floating motion secondary herringbone groove microstructure.

[0061] In some embodiments, as Figure 2 and Figure 3 As shown, the specific structures of two workpieces to be processed are respectively shown: the herringbone microgrooves to be etched on the inner hole surface of the bearing and the herringbone microgrooves to be etched on the radial surface of the bearing.

[0062] In some embodiments, as Figure 4 As shown:

[0063] When the low-frequency modulation pulse is at a high level, the high-frequency main pulses are output intensively (forming a pulse group); when the low-frequency modulation pulse is at a low level, the high-frequency main pulses stop completely (forming an interval). During the pulse interval (when the low-frequency modulation pulse is at a low level), the current returns to zero, forcing the passive film in the non-processing area to repair and suppressing stray corrosion. Within each low-frequency modulation pulse high-level cycle, the high-frequency main pulses appear in groups (discontinuous output), forming a periodic cycle of pulse cluster-interval-pulse cluster.

[0064] In some embodiments, as Figure 5 As shown:

[0065] The power supply system and electrolyte system have a coordinated pulse mechanism: when the pulsating pump is in the liquid supply off phase, the electrolyte flow in the machining gap stops, the power system pulse is in the pulse width phase, and electrolytic machining begins; when the pulsating pump is in the liquid supply on phase, the power system pulse is in the pulse interval phase, and the electrolyte flows into the machining gap at a high flow rate and pressure, removing the electrolytic products accumulated in the machining area, refreshing the electrolyte in the gap, restoring its concentration and conductivity, and electrolytic machining stops. This mechanism significantly improves the electrolyte flow state, product discharge, and heat transfer process in the narrow machining gap, thereby overcoming the inherent limitations of continuous liquid supply.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Any simple modification, equivalent replacement, or improvement made to the above embodiments by any person skilled in the art, without departing from the scope of the present invention and in accordance with the technical essence of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A precision electrochemical machining method for herringbone groove microstructures for air-bearing motion pairs, characterized by: A contoured cathode having a surface with a protruding structure complementary to the target herringbone groove is used to process a workpiece, and the workpiece is connected to an anode assembly; the protruding structure is the processing area, and an insulating coating is provided on the surface of the non-processing area outside the protruding structure; The electrolyte system intermittently supplies electrolyte to the machining gap, wherein the electrolyte is an acidic electrolyte; the power supply system charges the profiling cathode and the workpiece; During the machining process, the intermittent supply of electrolyte by the electrolyte system is synchronized with the pulse action of the power supply system: the machining pulse of the power supply system is started during the liquid supply closing phase of the electrolyte system, and the machining pulse of the power supply system is stopped and the electrolyte is renewed during the liquid supply opening phase of the electrolyte system.

2. The precision electrochemical machining method for the herringbone groove microstructure of the air-bearing motion pair according to claim 1, characterized in that: In the electrolyte system, electrolyte is intermittently supplied to the processing gap through a bidirectional side-flow flow field liquid cavity, and the bidirectional side-flow flow field liquid cavity includes a liquid storage cavity and a circumferential array guide channel. The electrolyte is diverted from the inlet to the opposite direction and flows through the processing gap.

3. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The liquid supply closing phase corresponds to the pulse width phase of the power supply system, and the liquid supply opening phase corresponds to the pulse interval phase of the power supply system.

4. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The power supply system is powered by a high-frequency group pulse power supply, which is composed of a high-frequency main pulse and a low-frequency modulation pulse to form a group pulse output in a unit cycle.

5. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The pH value of the electrolyte is 3-6, and the components include sodium nitrate and sodium citrate.

6. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The hovering stationary processing mode is adopted, and the contour cathode and the workpiece are kept relatively stationary and concentric during processing to form a uniform processing gap.

7. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The electrolyte renewal mentioned above refers to flushing the electrolyte into the machining gap, removing the electrolysis products accumulated in the machining area, renewing the electrolyte in the machining gap, and restoring its concentration and conductivity.

8. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The size of the protruding structure in the processing area of the contoured cathode surface is designed for reverse compensation according to the processing gap.

9. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 1, characterized in that: The power supply system includes a power supply anode and a power supply cathode, the power supply anode is connected to the anode assembly, and the power supply cathode is connected to the cathode assembly; the electrolyte system includes an inlet pipe and an outlet pipe, the cathode assembly has an inlet and an outlet, the inlet pipe is connected to the inlet of the cathode assembly, and the outlet pipe is connected to the outlet of the cathode assembly.

10. The precision electrochemical machining method for the herringbone groove microstructure of the air bearing pair according to claim 9, characterized in that: The electrochemical machining process includes the following steps: Step S1, assembling a cathode assembly and an anode assembly, wherein the cathode assembly is a contoured cathode; Step S2, installing and fixing the cathode assembly and the anode assembly, and adjusting the positions of the cathode assembly, the anode assembly, and the workpiece, detecting the axis offset of the workpiece relative to the cathode assembly in real time, and controlling the concentricity deviation of the workpiece to be within a specified range; Step S3, connecting the power anode of the power system to the anode assembly to make the workpiece positively charged, and connecting the power cathode of the power system to the cathode assembly to make the cathode assembly negatively charged; Step S4, connecting the liquid inlet pipe of the electrolyte system to the liquid inlet of the cathode assembly, and connecting the liquid outlet pipe to the liquid outlet of the cathode assembly; Step S5, opening the electrolyte system, allowing the electrolyte to flow through the machining gap between the cathode assembly and the workpiece, and checking the sealing condition; Step S6, perform short circuit detection; then set power parameters, turn on the power system and start electrolytic machining.

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