Method for efficient preparation of microelectrodes with large aspect ratio and online diameter measurement

Abstract

The present invention relates to a method for efficiently preparing a microelectrode with a large aspect ratio and measuring the diameter online, and belongs to the field of electrical machining technology. It is characterized in that the preparation process of the microelectrode is divided into three steps: ultra-large excess material removal, electrode shape trimming and micro-removal of material, and an electrode diameter online measurement function is added on the basis of electrode preparation. Among them, step 1 is ultra-large excess material removal, the purpose of which is to quickly reduce the electrode diameter; step 2 is to trim the electrode shape, to correct the electrode shape processed in step 1 and improve the electrode accuracy; step 3 is micro-removal of material, to perform micro-removal on the surface processed in step 2 again to improve the surface quality. After the electrode preparation is completed, the left and right sides of the rectangular gauge block are short-circuited to obtain their position coordinates, and then the difference between the coordinate difference of the two tool-setting points and the width of the gauge block is calculated to obtain the diameter of the microelectrode, thereby achieving the goal of integrating microelectrode preparation and online diameter measurement.

Description

Technical Field

[0001] The invention relates to a method for efficiently preparing a microelectrode with a large aspect ratio and measuring its diameter online, and belongs to the technical field of electrical machining. Background Art

[0002] Microfabrication technology supports the development of numerous foundational and cutting-edge disciplines, technologies, and industries, including nanotechnology, information, biology, intelligent manufacturing, high-end equipment, and new energy. Microscale structures, whether single or clustered, are the primary targets of microfabrication. Metal microstructures, such as microchannels, micropits, and microcracks, are core vehicles for realizing and enhancing key product functions and performance. They are widely used in lab-on-a-chip applications, microanalysis systems, microfluidic devices, fuel cell bipolar plates, and solar cell heat exchangers.

[0003] Preparing suitable microelectrodes is a prerequisite for machining metal microstructures. Due to the small diameter of microelectrodes and the large clamping errors, microelectrodes must typically be produced online to ensure machining accuracy. Furthermore, microelectrodes with large aspect ratios are typically prepared to compensate for electrode wear and ensure consistent microstructure dimensions. Wire electrode discharge grinding (EDG) involves material removal through the electrical discharge machining of a wire electrode and a rod-shaped electrode to be machined. During machining, a rod electrode mounted on the spindle head is fed axially as the spindle rotates, continuously feeding fresh wire into the machining area. This maintains excellent grinding accuracy throughout the entire machining process, making it one of the most widely used microelectrode machining methods. However, due to its point-to-point material removal process, this process suffers from low machining efficiency. Block electrode EDM (Electrode Discharge Grinding) involves material removal through the electrical discharge machining of a block electrode and a rod-shaped electrode to be machined. During machining, a rod electrode mounted on the spindle head is fed toward the block electrode as the spindle rotates, making it the simplest method for preparing microelectrodes online. However, due to the wear of the block electrode during machining, the resulting tapered microelectrode is poorly machined. Furthermore, combined processes such as micro-turning and micro-EDM, and self-drilling and wire-electrode discharge grinding have also been used to machine microelectrodes. However, these current combined processes suffer from complex procedures and cumbersome operations. Therefore, it is necessary to develop a simple electrode fabrication technology that balances machining accuracy and efficiency to address these challenges. Summary of the Invention

[0004] In view of the problems in the existing technology that processing accuracy and processing efficiency cannot be achieved at the same time and the process is complicated, the present invention proposes a method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online, in order to achieve the purpose of efficiently and accurately preparing microelectrodes with a large aspect ratio and measuring their diameters online.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for efficiently preparing a microelectrode with a large aspect ratio and measuring its diameter online, comprising:

[0007] Step 1: Use a U-shaped block electrode as the tool cathode and a rod-shaped electrode as the workpiece anode; the U-shaped block electrode is composed of an L-shaped metal block on the left and a rectangular gauge block on the right. The L-shaped metal block serves as the cathode of the discharge grinding process and together with the rod-shaped electrode forms a discharge channel to generate spark discharge, thereby removing the rod-shaped electrode material;

[0008] First, the U-shaped block electrode is fixed, and the rod electrode rotates around its own axis. The rod electrode determines the zero point of the machining coordinate system by a short-circuit tool setting method in front of and to the left of the L-shaped metal block of the U-shaped block electrode; then, the rod electrode is fed backward along the left side of the L-shaped metal block, with a feed distance R*(90%-95%), where R is the difference between the initial radius and the target radius of the rod electrode; finally, the machining parameters are adjusted, dielectric fluid is introduced into the machining area, and the machining power is turned on. The rod electrode is fed to the right for machining. When the inter-electrode gap between the rod electrode and the L-shaped metal block is smaller than the discharge gap, spark discharge occurs to erode material. As the rod electrode feeds, the electrode material is continuously eroded until there is no spark discharge and machining is stopped;

[0009] Step 2: Using the wire electrode as the tool cathode and the rod electrode processed in step 1 as the workpiece anode, based on the principle of EDM, the relative movement of the wire electrode and the rod electrode processed in step 1 further removes the electrode material, while significantly reducing the taper of the rod electrode processed in step 1 and improving its dimensional accuracy.

[0010] First, the wire electrode is continuously moved along the guide wheel, and the rod electrode rotates around its own axis. The rod electrode processed in step 1 is respectively used to obtain the zero point of the processing coordinate system on the side and upper end surface of the wire electrode along the symmetry center line of the guide wheel by a short-circuit tool setting method; then, the rod electrode processed in step 1 is fed R*(4%-9%) along the diameter direction of the wire electrode; finally, the processing parameters are adjusted, the dielectric fluid is introduced into the processing area and the processing power is turned on, and the rod electrode processed in step 1 is fed downward. When the inter-electrode gap between the rod electrode processed in step 1 and the wire electrode is smaller than the discharge gap, spark discharge occurs to erode the electrode material. As the rod electrode processed in step 1 is fed, the electrode material is continuously eroded until it stops after feeding a preset distance L, where L is the processing length of the rod electrode processed in step 1;

[0011] Step 3: The wire electrode is still used as the tool cathode, and the rod electrode processed in step 2 is used as the workpiece anode. Based on the principle of EDM, the relative movement between the wire electrode and the rod electrode processed in step 2 is used to remove a small amount of electrode material to ensure the processing accuracy and quality of the electrode preparation;

[0012] The end position of the electrode surface processed in step 2 is used as the starting position of step 3 processing. The processing parameters are adjusted, dielectric fluid is introduced into the processing area, and the processing power is turned on to start processing. The rod electrode processed in step 2 is fed R*(1%-2%) along the diameter direction of the wire electrode. After no spark discharge, the rod electrode processed in step 2 is fed upward. As the rod electrode processed in step 2 is fed, the electrode material is continuously etched until it stops after feeding a preset distance L, and the microelectrode preparation is completed.

[0013] Step 4: After the microelectrode is prepared, the microelectrode is rotated around its own axis and connected to the positive pole of the processing power supply. The rectangular gauge block is used as the measurement reference and is connected to the negative pole of the processing power supply. The left and right sides of the rectangular gauge block are short-circuited to determine the position coordinates O and O'. Then, the difference between the X-axis coordinates X1 of O and O' and the width w of the rectangular gauge block is calculated to obtain the diameter of the prepared microelectrode.

[0014] The rod-shaped electrodes are made of metal materials resistant to electrical corrosion.

[0015] The L-shaped metal block is made of copper-tungsten alloy material, and the wire-shaped electrode is made of copper material.

[0016] The accuracy grade of the rectangular gauge block is grade 0.

[0017] The dielectric liquid is deionized water with a conductivity range of 0.1-10 μS / cm.

[0018] The processing power supply is an RC power supply or a high-frequency pulse power supply.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention overcomes the problem that previous electrode preparation processes cannot take into account both processing efficiency and processing accuracy, and proposes an electrode preparation method based on different processing steps to achieve different processing goals. Among them, the processing goal of step 1 is to efficiently remove electrode material and improve processing efficiency, so a larger electrode feed ratio is set (the electrode feed ratio of this step accounts for the total electrode feed ratio), ranging from 90% to 95%; the processing goal of step 2 is to correct the electrode shape and improve processing accuracy, so the electrode feed ratio ratio range is set to 4% to 9%; the processing goal of step 3 is to reduce the surface roughness of the electrode and improve the processing quality, so the electrode feed ratio ratio range is set to 1% to 2%. The three steps each perform their respective functions and jointly achieve high-efficiency, high-precision and high-quality preparation of microelectrodes.

[0021] 2. The process of the present invention has high applicability and can meet the processing needs of rod electrodes with different initial diameters, and eliminate the original size error and clamping error of the rod electrodes. It is suitable for the processing of microelectrodes of different sizes and shapes to meet different processing requirements.

[0022] 3. The present invention can measure the diameter of the microelectrode online, accurately monitor the diameter change of the microelectrode, realize the preparation of high-precision microelectrodes, and avoid the clamping error caused by re-clamping the microelectrode after offline diameter measurement.

[0023] 4. The three steps of the microelectrode preparation process all utilize spark discharge to remove materials, and can be processed on the same processing device. The operation is simple, the processing cost is low, and it has great engineering potential and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the principle of the present invention;

[0025] Figure 2 Surface micromorphology of the microelectrode prepared in the present invention at different processing stages;

[0026] Figure 3 A photo of the microelectrode prepared according to the present invention;

[0027] The label names are: 1. Rod electrode, 1-1. Rod electrode after processing in step 1, 1-2. Rod electrode after processing in step 2, 1-3. Rod electrode after processing in step 3, 2. U-shaped block electrode, 2-1. L-shaped metal block, 2-2. Gauge block, 3. Processing power supply; 4. Wire electrode guide wheel, 5. Wire electrode. Implementation Method

[0028] The following will clearly and in detail describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In order to solve the problems existing in the prior art, such as Figures 1 to 3 As shown, the present invention provides a method for efficiently preparing a microelectrode with a large aspect ratio and measuring its diameter online. Taking a rod-shaped electrode with an initial diameter of 1 mm, a target diameter of 0.091 mm, a processing length of 2 mm, and a rectangular gauge block width of 10 mm as an example, the electrode preparation and diameter online measurement steps are as follows:

[0030] Step 1: Use a U-shaped block electrode 2 as the tool cathode and a rod-shaped electrode 1 as the workpiece anode; the U-shaped block electrode 2 is composed of an L-shaped metal block 2-1 on the left and a rectangular gauge block 2-2 on the right. The L-shaped metal block 2-1 serves as the cathode of the discharge grinding process and together with the rod-shaped electrode 1 forms a discharge channel to generate spark discharge, thereby removing the rod-shaped electrode material;

[0031] First, the U-shaped block electrode 2 is fixed, and the rod-shaped electrode 1 rotates around its own axis. The rod-shaped electrode 1 determines the zero point of the machining coordinate system by the short-circuit tool setting method in front of and to the left of the L-shaped metal block 2-1 of the U-shaped block electrode 2; then, the rod-shaped electrode 1 is fed backward along the left side of the L-shaped metal block 2-1, and the feed distance is 0.42 mm (the electrode feed amount accounts for 92.4%); finally, the machining parameters are adjusted, the dielectric fluid is introduced into the machining area and the machining power supply 3 is turned on, and the rod-shaped electrode 1 is fed to the right for machining. When the inter-electrode gap between the rod electrode 1 and the L-shaped metal block 2-1 is smaller than the discharge gap, spark discharge occurs to erode the material. As the rod-shaped electrode 1 is fed, the electrode material is continuously eroded until there is no spark discharge and the machining is stopped. The diameter of the rod-shaped electrode 1 is ground from the original diameter of 1 mm to 0.16 mm. The surface of the electrode after machining is covered with large micro-protrusion structures, such as Figure 2 (a)

[0032] Step 2: Using the wire electrode 5 as the tool cathode and the rod electrode 1-1 processed in step 1 as the workpiece anode, based on the principle of electrospark machining, the electrode material is further removed by the relative movement of the wire electrode (5) and the rod electrode 1 processed in step 1, while significantly reducing the taper of the rod electrode 1-1 processed in step 1 and improving its dimensional accuracy;

[0033] First, the wire electrode 5 is continuously moved along the guide wheel 4, and the rod electrode 1 rotates around its own axis. The rod electrode 1-1 processed in step 1 is respectively obtained along the symmetric center line of the guide wheel 4 on the side and upper end surface of the wire electrode 5 by the short-circuit tool setting method to obtain the zero point of the processing coordinate system; then, the rod electrode 1-1 processed in step 1 is fed 0.03 mm along the diameter direction of the wire electrode 5 (the electrode feed amount accounts for 6.6%); finally, the processing parameters are adjusted, the dielectric fluid is introduced into the processing area and the processing power supply 3 is turned on. The rod electrode 1-1 processed in step 1 is fed downward. When the inter-electrode gap between the rod electrode 1-1 processed in step 1 and the wire electrode 5 is less than the discharge gap, spark discharge occurs to erode the electrode material. As the rod electrode 1-1 processed in step 1 is fed, the electrode material is continuously eroded until it stops after feeding a preset distance of 2 mm. The rod electrode is ground from a diameter of 0.16 mm to a diameter of 0.1 mm, and the size of the micro-protrusion structure on the surface after processing is significantly reduced. Figure 2 (b)

[0034] Step 3: The wire electrode 5 is still used as the tool cathode, and the rod electrode 1-2 processed in step 2 is used as the workpiece anode. Based on the principle of electrospark machining, the wire electrode 5 and the rod electrode 1-2 processed in step 2 are moved relative to each other to remove a small amount of electrode material, thereby ensuring the machining accuracy and quality of the electrode preparation.

[0035] The end position of the rod electrode 1-2 processed in step 2 is used as the starting position of step 3 processing. The processing parameters are adjusted, dielectric fluid is introduced into the processing area, and the processing power supply 3 is turned on to start processing. The rod electrode 1-2 processed in step 2 is fed 0.005 mm along the diameter direction of the wire electrode 5 (the electrode feed amount accounts for 1%). After no spark discharge, the rod electrode 1-2 processed in step 2 is fed upward; as the rod electrode 1-2 processed in step 2 is fed, the electrode material is continuously etched until it stops after feeding a preset distance of 2 mm. The microelectrode preparation is completed, and the surface of the processed electrode is smooth and defect-free, as shown in FIG. Figure 2 (c)

[0036] Step 4: After the microelectrode is prepared, the microelectrode is rotated around its own axis and connected to the positive pole of the processing power supply 1. The rectangular gauge block 2-2 is used as the measurement reference and connected to the negative pole of the processing power supply 3. The left and right sides of the rectangular gauge block 2-2 are short-circuited and tool-set to determine the position coordinates O and O'. Then, the difference between the X-axis coordinates of O and O' and the width of the rectangular gauge block 2-2 (10 mm) is calculated to obtain the diameter of the prepared microelectrode. After measurement, the average diameter of the processed microelectrode is 91.1 μm, the effective length is 1981 μm, and the aspect ratio is 21.7. Figure 3 shown.

[0037] The rod-shaped electrode 1 is made of a rod-shaped pure tungsten material.

[0038] The L-shaped metal block 2 - 1 is made of copper-tungsten alloy material, and the wire electrode 5 is made of copper material and has a diameter of 0.2 mm.

[0039] The accuracy grade of the rectangular gauge block 2-2 is grade 0.

[0040] The dielectric liquid is deionized water with a conductivity of 1 μS / cm.

[0041] The processing power supply 3 is a high-frequency pulse power supply.

[0042] Specific examples are used in this specification to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be covered by the scope of the claims of the present invention.

Claims

1. A method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online, characterized in that The following processes are included: Step 1: Using a U-shaped block electrode (2) as a tool cathode and a rod-shaped electrode (1) as a workpiece anode; the U-shaped block electrode (2) is composed of an L-shaped metal block (2-1) on the left and a rectangular gauge block (2-2) on the right, wherein the L-shaped metal block (2-1) is used as a cathode in the discharge grinding process, and together with the rod-shaped electrode (1) constructs a discharge channel to generate spark discharge, thereby achieving the purpose of removing the rod-shaped electrode material; First, the U-shaped block electrode (2) is fixed, and the rod-shaped electrode (1) rotates around its own axis. The rod-shaped electrode (1) determines the zero point of the processing coordinate system in front of and to the left of the L-shaped metal block (2-1) of the U-shaped block electrode (2) by a short-circuit tool setting method; then, the rod-shaped electrode (1) is fed backward along the left side of the L-shaped metal block (2-1), and the feeding distance is R*(90%-95%), where R is the difference between the initial radius and the target radius of the rod-shaped electrode (1); finally, the processing parameters are adjusted, the dielectric fluid is introduced into the processing area, and the processing power supply (3) is turned on. The rod-shaped electrode (1) is fed to the right for processing. When the inter-electrode gap between the rod-shaped electrode (1) and the L-shaped metal block (2-1) is smaller than the discharge gap, spark discharge occurs to erode the material. As the rod-shaped electrode (1) is fed, the electrode material is continuously eroded until there is no spark discharge and the processing is stopped; Step 2: Using the wire electrode (5) as the tool cathode and the rod electrode (1-1) processed in step 1 as the workpiece anode, based on the principle of electrospark machining, the electrode material is further removed by the relative movement of the wire electrode (5) and the rod electrode (1) processed in step 1, while significantly reducing the taper of the rod electrode (1-1) processed in step 1 and improving its dimensional accuracy; First, the wire electrode (5) is continuously moved along the guide wheel (4), and the rod electrode (1) rotates around its own axis. The rod electrode (1-1) processed in step 1 is respectively provided with a zero point of a processing coordinate system along the symmetrical center line of the guide wheel (4) on the side and upper end surface of the wire electrode (5) by a short-circuit tool setting method. Then, the rod electrode (1-1) processed in step 1 is fed R*(4%-9%) along the diameter direction of the wire electrode (5). Finally, the processing parameters are adjusted, dielectric fluid is introduced into the processing area, and the processing power supply (3) is turned on. The rod electrode (1-1) processed in step 1 is fed downward. When the inter-electrode gap between the rod electrode (1-1) processed in step 1 and the wire electrode (5) is smaller than the discharge gap, spark discharge occurs to erode the electrode material. As the rod electrode (1-1) processed in step 1 is fed, the electrode material is continuously eroded until it stops after feeding a preset distance L, where L is the axial processing length of the rod electrode (1-1) processed in step 1. Step 3: The wire electrode (5) is still used as the tool cathode, and the rod electrode (1-2) processed in step 2 is used as the workpiece anode. Based on the principle of electrospark machining, the electrode material is removed in small amounts by the relative movement between the wire electrode (5) and the rod electrode (1-2) processed in step 2, thereby ensuring the machining accuracy and machining quality of the electrode preparation; The end position of the rod-shaped electrode (1-2) processed in step 2 is used as the starting position of the processing in step 3. The processing parameters are adjusted, dielectric fluid is introduced into the processing area, and the processing power is turned on (3) to start processing. The rod-shaped electrode (1-2) processed in step 2 is fed R*(1%-2%) along the diameter direction of the wire electrode (5). After no spark discharge, the rod-shaped electrode (1-2) processed in step 2 is fed upward. As the rod-shaped electrode (1-2) processed in step 2 is fed, the electrode material is continuously eroded until it stops after feeding a preset distance L, and the microelectrode preparation is completed. Step 4: After the microelectrode is prepared, the microelectrode is rotated around its own axis and connected to the positive pole of the processing power supply (1). The rectangular gauge block (2-2) is used as a measurement reference and connected to the negative pole of the processing power supply (3). The left and right sides of the rectangular gauge block (2-2) are short-circuited to determine the position coordinates O and O', and then the difference X1 between the X-axis coordinates of O and O' and the width w of the rectangular gauge block (2-2) is calculated to obtain the diameter of the prepared microelectrode.

2. The method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online according to claim 1, characterized in that: The rod-shaped electrode (1) is made of a metal material that is resistant to electrical corrosion.

3. The method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online according to claim 1, characterized in that: The L-shaped metal block (2-1) is made of a copper-tungsten alloy material, and the wire-shaped electrode (5) is made of a copper material.

4. The method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online according to claim 1, wherein: The accuracy grade of the rectangular gauge block (2-2) is grade 0.

5. The method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online according to claim 1, characterized in that: The dielectric liquid is deionized water with a conductivity range of 0.1-10 μS / cm.

6. The method for efficiently preparing microelectrodes with a large aspect ratio and measuring their diameters online according to claim 1, characterized in that: The processing power supply (3) is an RC power supply or a high-frequency pulse power supply.

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