Electrochemical grinding device for a multi-stage multi-shape guide wire mandrel

Abstract

The application discloses a kind of electrochemical grinding devices of multi-stage multi-shape guide wire mandrel, applied in the field of nerve micro-guide wire processing, including rack, the surface of the rack is provided with laser measuring instrument, the surface of the rack is provided with moving mechanism, the surface of the moving mechanism is provided with fixed mechanism, the surface of the rack is provided with ultrasonic water tank;The present application is processed by non-contact electrochemistry throughout, without mechanical stress, without high temperature thermal damage, without damaging the performance of nickel-titanium alloy material, surface roughness Ra≤0.05 μm, diameter control accuracy ±2 μm, can realize 0.05mm micro mandrel, multi-stage taper precision machining, meet the stringent standards of medical guide wire mandrel, second electrode and moving mechanism, adapt to multi-diameter, multi-shape, multi-stage mandrel continuous processing, support multi-workpiece synchronous processing, ultrasonic auxiliary break passivation film, material removal rate is improved by 30%-50%, electrolyte circulation filtration guarantees processing stability, high yield.

Description

Technical Field

[0001] This invention relates to the field of neural microwire fabrication, and particularly to an electrochemical grinding apparatus for a multi-stage, multi-shaped guidewire mandrel. Background Technology

[0002] As a precision navigator in neurointerventional surgery, the core component of the neuroguidewire is the mandrel, whose manufacturing precision directly determines the maneuverability of the surgical instruments and patient safety. Specifically, the mandrel needs to achieve extremely high diameter accuracy (±2μm) to ensure smooth and precise advancement within the blood vessel; its surface roughness (Ra≤0.1μm) must be extremely smooth to minimize friction and damage to the vessel wall; at the same time, its geometry, such as precise tapered tapers and specific bending sections, also needs to be precisely controlled to ensure the guidewire's smooth passage and stable positioning between different vascular branches.

[0003] However, meeting these stringent manufacturing requirements poses a significant challenge to existing processing equipment. Currently, commonly used centerless grinders in China, such as those from Haotman and Fuxincheng, have significant limitations in their processing capabilities: grinding lengths are typically limited to 0-350mm, multi-stage continuous grinding of different diameters is impossible, the minimum grindable dimension is only 0.08mm, and the overall accuracy is only ±0.015mm. These specifications are significantly inferior to the precision requirements of neural microwire mandrels and cannot meet production needs at all.

[0004] In contrast, imported high-end centerless grinders demonstrate superior technological capabilities. These machines typically possess longer grinding capacities (up to 0-500mm), support 3-4 stages of continuous grinding with different diameters, and achieve more precise geometric control. Their minimum grinding dimension can reach 0.05mm, and their machining accuracy is as high as ±0.005mm, fully meeting or even exceeding the manufacturing standards for neural microwire mandrels. Currently, mainstream imported centerless grinder brands on the market include Royal Master and Glebar. Of course, these high-performance machines also come with high costs, with prices generally ranging from 3.5 million to 5 million RMB.

[0005] A search of Chinese patents revealed publication number CN203495765U, which discloses a surface grinding device based on dual electrolysis. The device includes an electrochemical grinding module, an online electrolytic dressing module, a power supply, an electrolyte supply device, and a controller. The electrochemical grinding module comprises a workpiece mounting bracket, a workpiece electrolytic dressing device, and a workpiece drive device. The online electrolytic dressing module includes a grinding wheel, a grinding wheel electrolytic dressing device, and a grinding wheel drive device, with the outer circumference of the grinding wheel tangent to the outer circumference of the workpiece. The electrolyte supply device has multiple outlets, located above the contact points between the workpiece and the grinding wheel, the workpiece electrolytic dressing device and the workpiece, and the grinding wheel electrolytic dressing device and the grinding wheel. The cathode of the power supply is connected to both the workpiece electrolytic dressing device and the grinding wheel electrolytic dressing device, while the anode is connected to both the workpiece and the grinding wheel. Both the workpiece drive device and the grinding wheel drive device are controlled by the controller. The advantages of this invention are: improved workpiece machining accuracy consistency, reduced processes, and increased efficiency.

[0006] Traditional mechanical grinding machines face multiple severe technical bottlenecks when machining neural microwire mandrels, which directly limit the improvement of product performance:

[0007] The inherent drawbacks of contact machining: Grinding machines involve direct contact between the grinding wheel or head and the mandrel during machining. This mechanical stress easily induces microcracks (depth ≥ 10 μm) and plastic deformation of the material on the mandrel surface. For critical materials like nickel-titanium alloys, which rely on precise phase transformation properties to achieve hyperelasticity, this damage can be catastrophic, directly destroying their core properties and affecting the shape memory and hyperelastic performance of the guidewire.

[0008] Unavoidable thermal damage: The localized high temperatures (often exceeding 300°C) generated during grinding are another insurmountable challenge. High temperatures not only cause oxidation on the material surface, forming an oxide layer with a thickness of ≥5μm, but more seriously, this oxide layer significantly affects the biocompatibility of the material, such as causing decreased cell adhesion, which may lead to adverse vascular reactions.

[0009] Limitations of microscale machining capabilities: When machining tiny diameter mandrels, especially high-performance microguidewires requiring multi-stage precision dimensions, the accuracy bottleneck of conventional grinding machines becomes glaringly apparent. Their wheel positioning accuracy (typically ±10μm) and feed resolution (generally ≥5μm) are far from meeting the demands of sub-micron level machining. Furthermore, micromandrels are highly susceptible to bending during clamping, and the resulting deflection (often >20μm) introduces additional machining errors.

[0010] These processing challenges ultimately manifest in the performance of end products, such as neural microwires. Currently, some neural microwires used clinically exhibit shortcomings: their stability is sometimes insufficient, and they are prone to displacement in complex vascular environments. This not only affects surgical outcomes but may also require repeated procedures, undoubtedly increasing patient suffering and surgical risks. Simultaneously, the structural design or material properties of some products limit their lifespan, making it difficult to meet the long-term use requirements of certain clinical scenarios. This is related to the failure to achieve optimal precision and surface quality during manufacturing. To address these issues, we propose an electrochemical grinding device for multi-stage, multi-shaped guidewire mandrels. Summary of the Invention

[0011] The purpose of this invention is to provide an electrochemical grinding device for a multi-stage, multi-shaped guide wire mandrel, which has the advantages of avoiding heat loss problems, high processing accuracy, and low cost.

[0012] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an electrochemical grinding device for a multi-stage, multi-shaped guide wire mandrel, comprising a frame, a laser measuring instrument mounted on the surface of the frame, a moving mechanism disposed on the surface of the frame, a fixing mechanism disposed on the surface of the moving mechanism, an ultrasonic water tank mounted on the surface of the frame, an electrolysis mechanism disposed inside the ultrasonic water tank, a power supply mounted on the surface of the frame, the positive and negative terminals of the power supply being electrically connected to a positive wire and a negative wire, respectively, a liquid storage tank disposed inside the frame, an electrolyte filter element mounted on the surface of the liquid storage tank, a circulating water pump mounted on the surface of the electrolyte filter element, and a return pipe connected to the surface of the liquid storage tank.

[0013] Using the above technical solution, through non-contact electrochemical processing, there is no mechanical stress or high-temperature thermal damage, and the performance of nickel-titanium alloy material is not damaged. The surface roughness Ra≤0.05μm and the diameter control accuracy±2μm can achieve precise processing of 0.05mm micro mandrels and multi-stage gradual taper, meeting the stringent standards of medical guidewire mandrels. The second electrode and moving mechanism are suitable for continuous processing of mandrels with multiple diameters, shapes, and stages, and support simultaneous processing of multiple workpieces. Ultrasonic assistance is used to break the passivation film, which improves the material removal rate by 30%-50%. Electrolyte circulation filtration ensures processing stability and high yield.

[0014] The present invention is further configured such that: the moving mechanism includes a transverse guide rail, the transverse guide rail is mounted on the surface of the frame, a first motor is mounted on the surface of the transverse guide rail, a vertical guide rail is mounted on the surface of the transverse guide rail, and a second motor is mounted on the top of the vertical guide rail.

[0015] By adopting the above technical solution and setting up a moving mechanism, it is possible to move up, down, left, and right.

[0016] The present invention is further configured such that: the fixing mechanism includes a first fixing plate, the first fixing plate is mounted on the surface of the vertical guide rail, and the surface of the first fixing plate is electrically connected to one end of the positive electrode wire; a first guide wire is mounted on the surface of the first fixing plate, and a first gravity weight is mounted on the bottom of the first guide wire.

[0017] By adopting the above technical solution, a fixing mechanism is set up to fix the first guide wire on the first fixed plate, and the first gravity drop straightens the first guide wire, which facilitates processing.

[0018] The invention is further configured such that: the fixing mechanism includes a second fixing disk, the second fixing disk is mounted on the surface of a vertical guide rail, a third motor is mounted on the surface of the second fixing disk, the output end of the third motor is connected to a first gear via a coupling, a turntable clamp is mounted on the inner wall of the second fixing disk, a second guide wire is mounted on the bottom of the turntable clamp, a second gravity weight is mounted on the bottom of the second guide wire, a first conductive wheel is mounted on the top of the turntable clamp, a second gear is mounted on the bottom of the first conductive wheel, a belt is drivingly connected to the surfaces of the second gear and the first gear, a conductive wheel support frame is mounted on the surface of the second fixing disk, and the surface of the conductive wheel support frame is electrically connected to the positive electrode wire, a conductive central shaft is mounted inside the conductive wheel support frame, a second conductive wheel is mounted on the surface of the conductive central shaft, and the surfaces of the first conductive wheel and the second conductive wheel are in contact, and a spring is installed between the conductive wheel support frame and the second fixing disk.

[0019] By adopting the above technical solution, a fixing mechanism is set up, and the third motor drives the first gear and belt to drive the second gear to rotate. The rotation of the second gear drives the turntable clamp to rotate the second guide wire, which facilitates processing.

[0020] The present invention is further configured such that: the electrolysis mechanism includes a first fixed base, the first fixed base is installed inside the ultrasonic water tank, the first fixed base is installed inside the first fixed base and the bottom of the first electrolyte tank is connected to the circulating water pump, and the top of the first motor liquid tank is connected to one end of the return pipe, the inner wall of the electrolyte tank is installed with a first electrode, and the first electrode is electrically connected to the negative electrode wire.

[0021] By adopting the above technical solution and setting up an electrolysis mechanism, electrolysis can be facilitated.

[0022] The present invention is further configured such that: the electrolysis mechanism includes a second fixed base, the second fixed base is installed inside the ultrasonic water tank, a second electrolyte tank is installed inside the second fixed base, and the surface of the second electrolyte tank is connected to one end of the reflux pipe, and the top of the electrode tank is connected to the circulating water pump, a second electrode is installed on the inner wall of the second electrolyte tank, and the surface of the second electrode is electrically connected to the negative electrode wire, and a third electrode is installed inside the second electrode.

[0023] By adopting the above technical solution and setting up an electrolysis mechanism, electrolysis can be facilitated.

[0024] A pulsed electrochemical grinding method for a multi-stage, multi-shape guide wire mandrel includes the following steps:

[0025] S1. Clamping and Alignment: Fix the guide wire mandrel as the anode to the fixing mechanism, and use a gravity drop at the bottom to straighten the mandrel. Adjust the coaxiality of the mandrel and the electrode of the electrolysis mechanism through the moving mechanism to make the eccentricity deviation <10μm.

[0026] S2. Electrolyte circulation supply: The circulating water pump sends the electrolyte in the liquid storage tank through the electrolyte filter element for three-stage filtration and into the electrolyte tank of the electrolysis mechanism. The return pipe simultaneously realizes the electrolyte return circulation.

[0027] S3, Pulsed Electrochemical Dissolution: A pulsed DC current is applied to the anode mandrel and cathode electrode. The surface of the mandrel undergoes metal dissolution and oxidation reactions in the electrolyte. The ultrasonic water tank breaks the passivation film on the surface of the mandrel through high-frequency vibration.

[0028] S4. Multi-stage taper forming: The PLC system receives the preset diameter and length parameters of the mandrel, calculates the moving distance and speed, controls the moving mechanism to precisely adjust the axial moving speed of the mandrel, and moves at a constant speed in the straight section and at a variable speed in the inclined taper section to complete the multi-stage gradual taper processing.

[0029] S5. Online closed-loop detection: The laser measuring instrument collects mandrel diameter data in real time and dynamically compensates for processing parameters to ensure diameter control accuracy.

[0030] The present invention is further configured such that: the peak voltage of the pulsed DC current in step S3 is 10-50V, the frequency is 10-100kHz, and the average current density is 5-20A / cm²; the ultrasonic frequency is 40-80kHz, and the power is 10-30W / cm², thereby increasing the material removal rate by 30%-50% after the passivation film is broken.

[0031] The present invention is further configured such that: the electrolyte is a mixture of ethanol and deionized water in a volume ratio of 1:1, with the addition of 3%-5% NaCl and 0.5% sodium dodecyl sulfate, and the conductivity is controlled at 15-25 mS / cm.

[0032] A chemical grinding method for a multi-stage, multi-shape guide wire mandrel includes the following steps:

[0033] S1. Core wire clamping and positioning: Fix the non-machined end of the core wire to the fixed plate, assemble the gravity weight at the machined end, and adjust the coaxiality of the core wire to a deviation of <10μm.

[0034] S2. Preparation of etching solution: For nickel-titanium alloy core wire, prepare an etching solution containing 1%~15% hydrofluoric acid and 5%~40% nitric acid.

[0035] S3. Chemical dissolution processing: The core wire is immersed in the corrosion solution to undergo an oxidation-reduction reaction. Ultrasonic waves are used to help break the passivation film on the surface of the core wire and control the corrosion reaction time.

[0036] S4. Variable Diameter Size Control: The servo motor moves the core wire at varying speeds according to preset inclined cone diameter and length parameters to achieve multi-stage variable diameter processing.

[0037] S5. Product Filtration and Circulation: The electrolyte circulation system continuously filters the processed products, maintaining the cleanliness of the etchant and the stability of the process.

[0038] In summary, the present invention has the following beneficial effects:

[0039] This invention utilizes a fully non-contact electrochemical machining process, eliminating mechanical stress and high-temperature thermal damage, without compromising the properties of the nickel-titanium alloy material. It achieves a surface roughness Ra≤0.05μm and a diameter control accuracy of ±2μm, enabling precise machining of 0.05mm micro-mandrels and multi-stage gradual taper, meeting the stringent standards for medical guidewire mandrels. The second electrode and moving mechanism are adaptable to continuous machining of mandrels with multiple diameters, shapes, and stages, supporting simultaneous machining of multiple workpieces. Ultrasonic-assisted removal of the passivation film increases material removal rate by 30%-50%, and electrolyte circulation filtration ensures processing stability and a high yield rate. Attached Figure Description

[0040] Figure 1 This is a three-dimensional structural view of Embodiment 1 of the present invention;

[0041] Figure 2 This is a three-dimensional cross-sectional view of the structure of Embodiment 1 of the present invention;

[0042] Figure 3 This is the present invention. Figure 2 Enlarged view of the structure at point A in the middle;

[0043] Figure 4 This is a three-dimensional structural view of Embodiment 2 of the present invention;

[0044] Figure 5 This is a three-dimensional cross-sectional view of the structure of Embodiment 2 of the present invention;

[0045] Figure 6 This is a perspective view of the fixing mechanism in Embodiment 2 of the present invention;

[0046] Figure 7 This is the present invention. Figure 5 Enlarged view of the structure at point A in the middle;

[0047] Figure 8 This is a schematic diagram of the segmented length of the multi-stage guidewire mandrel of the present invention;

[0048] Figure 9 This is a schematic diagram of the input interface for the oblique cone length, diameter, and power parameters of the guide wire mandrel processing according to the present invention;

[0049] Figure 10 This is a schematic diagram of the servo motor moving speed and speed subdivision control parameters of the present invention;

[0050] Figure 11 This is a schematic diagram of the online diameter detection data and acquisition position display interface of the laser diameter measuring instrument of the present invention;

[0051] Figure 12 This is a schematic diagram of the overall structure of the multi-stage gradually tapered guide wire mandrel of the present invention;

[0052] Figure 13 This is a schematic diagram of the full parameter setting interface for the guide wire mandrel processing of the present invention;

[0053] Figure 14 This is a schematic diagram of the variable speed subdivision movement control parameters of the servo motor with inclined cone segment according to the present invention;

[0054] Figure 15 This is a schematic diagram of the interface for diameter detection, data acquisition, and grinding status display of the product of this invention.

[0055] Reference numerals: 1. Frame; 2. Laser measuring instrument; 3. Moving mechanism; 4. Fixing mechanism; 5. Ultrasonic water tank; 6. Electrolysis mechanism; 7. Power supply; 8. Positive lead wire; 9. Negative lead wire; 10. Liquid storage tank; 11. Electrolyte filter element; 12. Circulating water pump; 13. Return pipe; 14. Horizontal guide rail; 15. First motor; 16. Vertical guide rail; 17. Second motor; 18. First fixed plate; 19. First guide wire; 20. First gravity drop; 21. Second fixed plate 21. Fixed plate; 22. Third motor; 23. First gear; 24. Turntable clamp; 25. Second guide wire; 26. Second gravity dropper; 27. First conductive wheel; 28. Second gear; 29. ​​Belt; 30. Conductive wheel support frame; 31. Conductive central shaft; 32. Second conductive wheel; 33. Spring; 34. First electrolyte tank; 35. First electrode; 36. Second fixed base; 37. Second electrolyte tank; 38. Second electrode; 39. Third electrode; 40. First fixed base. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the accompanying drawings.

[0057] Example 1:

[0058] refer to Figure 1 , Figure 2 and Figure 3 An electrochemical grinding device for a multi-stage, multi-shaped guide wire mandrel includes a frame 1, a laser measuring instrument 2 mounted on the surface of the frame 1, a moving mechanism 3 disposed on the surface of the frame 1, a fixing mechanism 4 disposed on the surface of the moving mechanism 3, an ultrasonic water tank 5 mounted on the surface of the frame 1, an electrolysis mechanism 6 disposed inside the ultrasonic water tank 5, a power supply 7 mounted on the surface of the frame 1, the positive and negative terminals of the power supply 7 being electrically connected by a positive wire 8 and a negative wire 9, respectively, a liquid storage tank 10 disposed inside the frame 1, an electrolyte filter element 11 mounted on the surface of the liquid storage tank 10, and a circulating water pump 12 mounted on the surface of the electrolyte filter element 11. The surface of the body storage box 10 is connected to the return pipe 13. Through the entire non-contact electrochemical processing, there is no mechanical stress or high temperature thermal damage, and the performance of nickel-titanium alloy material is not damaged. The surface roughness Ra≤0.05μm and the diameter control accuracy±2μm can realize the precise processing of 0.05mm micro mandrels and multi-stage gradual taper, which meets the stringent standards of medical guide wire mandrels. The second electrode 38 and the moving mechanism 3 are adapted to the continuous processing of mandrels with multiple diameters, shapes and stages, and support the synchronous processing of multiple workpieces. Ultrasonic assistance is used to break the passivation film, which improves the material removal rate by 30%-50%. Electrolyte circulation filtration ensures processing stability and high yield.

[0059] refer to Figure 1 and Figure 2 The moving mechanism 3 includes a transverse guide rail 14, which is mounted on the surface of the frame 1. A first motor 15 is mounted on the surface of the transverse guide rail 14, and a vertical guide rail 16 is mounted on the surface of the transverse guide rail 14. A second motor 17 is mounted on the top of the vertical guide rail 16. By setting the moving mechanism 3, it is possible to move up, down, left, and right.

[0060] refer to Figure 2 and Figure 3 The fixing mechanism 4 includes a first fixing plate 18, which is mounted on the surface of the vertical guide rail 16 and is electrically connected to one end of the positive electrode wire 8. A first guide wire 19 is mounted on the surface of the first fixing plate 18, and a first gravity weight 20 is mounted on the bottom of the first guide wire 19. By setting the fixing mechanism 4, the first guide wire 19 is fixed on the first fixing plate 18, and the first gravity weight 20 straightens the first guide wire 19, which is convenient for processing.

[0061] refer to Figure 2 and Figure 3The electrolysis mechanism 6 includes a first fixed base 40, which is installed inside the ultrasonic water tank 5. A first electrolyte tank 34 is installed inside the first fixed base 40, and the bottom of the first electrolyte tank 34 is connected to the circulating water pump 12. The top of the first motor tank 15 is connected to one end of the return pipe 13. A first electrode 35 is installed on the inner wall of the electrolyte tank, and the first electrode 35 is electrically connected to the negative electrode wire 9. Electrolysis is facilitated by setting the electrolysis mechanism 6.

[0062] A pulsed electrochemical grinding method for a multi-stage, multi-shape guide wire mandrel includes the following steps:

[0063] S1. Clamping and alignment: Fix the guide wire mandrel as the anode to the fixing mechanism 4, and use a gravity drop at the bottom to straighten the mandrel. Adjust the coaxiality of the mandrel and the electrode of the electrolysis mechanism 6 through the moving mechanism 3 so that the eccentricity deviation is <10μm.

[0064] S2, Electrolyte circulation supply: The circulating water pump 12 sends the electrolyte in the liquid storage tank 10 through the electrolyte filter element 11 for three-stage filtration and then into the electrolyte tank of the electrolysis mechanism 6. The return pipe 13 simultaneously realizes the electrolyte return circulation.

[0065] S3, Pulsed electrochemical dissolution: Power supply 7 applies pulsed DC current to the anode core and cathode electrode. Metal dissolution and oxidation reactions occur on the surface of the core in the electrolyte. The ultrasonic water tank 5 breaks the passivation film on the surface of the core through high-frequency vibration.

[0066] S4. Multi-stage taper forming: The PLC system receives the preset diameter and length parameters of the mandrel, calculates the moving distance and speed, and controls the moving mechanism 3 to precisely adjust the axial moving speed of the mandrel. The straight section moves at a constant speed, and the inclined taper section moves at a variable speed and subdivided speed to complete the multi-stage gradual taper processing.

[0067] S5. Online closed-loop detection: The laser measuring instrument 2 collects mandrel diameter data in real time, dynamically compensates for processing parameters, and ensures diameter control accuracy.

[0068] In step S3, the peak voltage of the pulsed DC current is 10-50V, the frequency is 10-100kHz, and the average current density is 5-20A / cm²; the ultrasonic frequency is 40-80kHz, the power is 10-30W / cm², and the material removal rate is increased by 30%-50% after the passivation film is broken.

[0069] The electrolyte is a mixture of ethanol and deionized water in a 1:1 volume ratio, with the addition of 3%-5% NaCl and 0.5% sodium dodecyl sulfate, and the conductivity is controlled at 15-25 mS / cm.

[0070] Example 2:

[0071] refer to Figure 4 , Figure 5 , Figure 6 and Figure 7 The fixing mechanism 4 includes a second fixing plate 21, which is mounted on the surface of the vertical guide rail 16. A third motor 22 is mounted on the surface of the second fixing plate 21. The output end of the third motor 22 is connected to a first gear 23 via a coupling. A turntable clamp 24 is mounted on the inner wall of the second fixing plate 21. A second guide wire 25 is mounted on the bottom of the turntable clamp 24. A second gravity weight 26 is mounted on the bottom of the second guide wire 25. A first conductive wheel 27 is mounted on the top of the turntable clamp 24. A second gear 28 is mounted on the bottom of the first conductive wheel 27. A belt 29 is connected to the surfaces of the second gear 28 and the first gear 23 for transmission. A conductive wheel support frame 30 is mounted on the surface of the second fixed plate 21, and the surface of the conductive wheel support frame 30 is electrically connected to the positive electrode wire 8. A conductive central shaft 31 is installed inside the conductive wheel support frame 30, and a second conductive wheel 32 is mounted on the surface of the conductive central shaft 31. The surfaces of the first conductive wheel 27 and the second conductive wheel 32 are in contact. A spring 33 is installed between the conductive wheel support frame 30 and the second fixed plate 21. By setting a fixing mechanism 4, the third motor 22 drives the first gear 23 and the belt 29 to drive the second gear 28 to rotate. The rotation of the second gear 28 drives the turntable clamp 24 to rotate the second guide wire 25, which facilitates processing.

[0072] refer to Figure 5 and Figure 7 The electrolysis mechanism 6 includes a second fixed base 36, which is installed inside the ultrasonic water tank 5. A second electrolyte tank 37 is installed inside the second fixed base, and the surface of the second electrolyte tank 37 is connected to one end of the return pipe 13. The top of the electrode tank is connected to the circulating water pump 12. A second electrode 38 is installed on the inner wall of the second electrolyte tank 37, and the surface of the second electrode 38 is electrically connected to the negative electrode wire 9. A third electrode 39 is installed inside the second electrode 38. Electrolysis is facilitated by setting the electrolysis mechanism 6.

[0073] A chemical grinding method for a multi-stage, multi-shape guide wire mandrel includes the following steps;

[0074] S1. Core wire clamping and positioning: Fix the non-machined end of the core wire to the fixed plate, assemble the gravity weight at the machined end, and adjust the coaxiality of the core wire to a deviation of <10μm.

[0075] S2. Preparation of etching solution: For nickel-titanium alloy core wire, prepare an etching solution containing 1%~15% hydrofluoric acid and 5%~40% nitric acid.

[0076] S3. Chemical dissolution processing: The core wire is immersed in the corrosion solution to undergo an oxidation-reduction reaction. Ultrasonic waves are used to help break the passivation film on the surface of the core wire and control the corrosion reaction time.

[0077] S4. Variable Diameter Size Control: The servo motor moves the core wire at varying speeds according to preset inclined cone diameter and length parameters to achieve multi-stage variable diameter processing.

[0078] S5. Product Filtration and Circulation: The electrolyte circulation system continuously filters the processed products, maintaining the cleanliness of the etchant and the stability of the process.

[0079] Brief description of the process: Pulse electrochemical grinding works by using a core wire as the anode and a tool electrode as the cathode, applying a pulsed direct current (peak voltage 10-50V, frequency 10-100kHz). In the electrolyte (ethanol-deionized water mixture containing 3%-5% NaCl), an electrochemical reaction occurs on the anode surface: metal dissolution reaction: M-ne - → M n+ (M represents metallic elements such as Ni and Ti) Oxidation reaction: 2H₂O - 4e⁻ - → O2↑+4H + (Promoting surface oxide film formation) During the pulse interval, hydrogen evolution reaction occurs at the cathode: 2H₂O + 2e⁻ - → H2↑ + 2OH - To maintain electrolyte neutrality, the passivation film removal schemes include: Scheme 1: Installing a high-frequency ultrasonic generator outside the chemical reaction tank. The acoustic vibrations break down the oxide film (≤2μm thick) formed on the anode surface, exposing a fresh metal surface and increasing the electrochemical dissolution rate by 30%-50%. Scheme 2: Connecting a high-frequency ultrasonic generator to a converter connector and physically fixing the non-machined end of the core wire, allowing the anode workpiece to carry acoustic waves. The acoustic vibrations break down the oxide film (≤2μm thick) formed on the anode surface, exposing a fresh metal surface and increasing the electrochemical dissolution rate by 30%-50%. Scheme 3: Using atmospheric pressure plasma treatment. The working gas is a mixture of argon and oxygen (volume ratio 9:1), with a plasma jet power of 100-300W, a treatment distance of 5-15mm, and a scanning speed of 1-5mm / s. This activates the core wire surface online, removing organic contaminants and generating a hydrophilic surface, enhancing the wettability of the corrosion solution, assisting in the removal of the passivation film, and increasing the material removal rate by 20%-40%. The principle of multi-stage oblique tapered core wire is based on the principle of anodic decomposition and cathodic adsorption. It utilizes the residence time of the electric field between the anode core wire and the cathode electrode to realize the reduction of core wire material or diameter.

[0080] The anode core wire (workpiece) is mounted on a vertical guide rail 16 via a fixed disc device. The PLC receives the diameter D value and the length L value of each segment of the core wire at key positions. It calculates the required moving distance and speed for each position based on the diameter and the length of the inclined cone using a computational logic function equation. Then, it controls a servo motor to precisely control the speed and distance of the anode core wire's up-and-down movement, thereby achieving the reduction of material at each position of the anode core wire and the length of each inclined cone. The moving speed of the second motor 17 for the anode core wire is determined as follows:

[0081] After determining parameters such as electrolyte concentration, temperature, ultrasonic power, current, and anode material, the grinding speed *vgrind* of the core wire radius under these parameter settings is first tested using a trial run machine. Then, the servo motor speed is adjusted until a speed *v0* is determined, at which the core wire can be ground to any constant wire diameter. Once *vgrind* and *v0* are determined, the required motor speed for any stage of the tapered section can be calculated based on the slope *a* of the wire radius in each tapered segment of the multi-stage tapered core wire (automatically calculated from the diameter *D* input by the PCL and the length *L* of each stage according to *r*=*a*l*+b*, where *r* is the wire radius and *l* is the wire length position). The motor speed *v* is calculated using the following formula:

[0082]

[0083] To ensure that the electric field strength is uniform across all positions of the anode workpiece, the core wire workpiece needs to be rotated when the electric field is applied.

[0084] When the anode core wire interacts with the electric field of the cathode electrode, the electrolyte level completely submerges the upper edge of the electrode copper tube.

[0085] The principle of pulsed electrochemical grinding involves using a mandrel as the anode and a tool electrode as the cathode, applying a pulsed direct current (peak voltage 10-50V, frequency 10-100kHz). In the electrolyte (ethanol-deionized water mixture containing 3%-5% NaCl), an electrochemical reaction occurs on the anode surface: a metal dissolution reaction: M-ne - → M n+ (M represents metallic elements such as Ni and Ti) Oxidation reaction: 2H₂O - 4e⁻ - → O2↑+4H + (Promoting surface oxide film formation) During the pulse interval, hydrogen evolution reaction occurs at the cathode: 2H₂O + 2e⁻ - →H2↑+ 2OH - Maintaining electrolyte neutrality. Using a frequency of 40–80 kHz and a power of 10–30 W / cm², processing performance is improved through the following synergistic effects. Passivation film removal scheme one: A high-frequency ultrasonic generator is installed outside the chemical reaction tank. The acoustic vibrations break down the oxide film (thickness ≤2μm) formed on the anode surface, exposing a fresh metal surface and promoting an increase in the electrochemical dissolution rate by 30%–50%. Passivation film removal scheme two: A high-frequency ultrasonic generator is connected to the non-processing end of a conversion connector, physically fixing the core wire. This allows the anode workpiece to carry acoustic waves, which break down the oxide film (thickness ≤2μm) formed on the anode surface, exposing a fresh metal surface and promoting an increase in the electrochemical dissolution rate by 30%–50%.

[0086] The principle of multi-stage oblique tapered core wire is based on the principle of anodic decomposition and cathodic adsorption. A precision cathode electrode with a specially shaped design is created according to the final required core wire shape and structural dimensions, reducing the amount of material and the length of each oblique taper at each position of the anode core wire. When the anode core wire interacts with the cathode electrode electric field, the electrolyte level completely submerges the entire cathode. To ensure uniform electric field strength at all positions of the anode workpiece, the core wire workpiece needs to rotate during the application of the electric field.

[0087] Chemical grinding is a direct oxidation-reduction reaction grinding method using an etchant. It achieves material dissolution through a direct chemical reaction (oxidation-reduction reaction) between the metal and the etchant. Simultaneously, high-precision grinding of the guide wire is achieved by controlling the removal of the passivation film and the reaction time, contact method, and contact area between the workpiece and the etchant (the corrosion rate depends on the metal activity, etchant concentration, and temperature, as well as the passivation film removal rate and isotropic uniform corrosion).

[0088] Ultrasonic-assisted strengthening, using frequencies of 40–80 kHz and power of 10–30 W / cm², improves processing performance through the following synergistic effects: Passivation film removal scheme one involves installing a high-frequency ultrasonic generator outside the chemical reaction tank. The acoustic vibrations break down the oxide film (thickness ≤2μm) formed on the workpiece surface, exposing a fresh metal surface and promoting a 20%–50% increase in the chemical dissolution rate.

[0089] The second method for removing the passivation film involves connecting a high-frequency ultrasonic generator to the non-machined end of the core wire via a physical connection. This allows the workpiece to carry its own sound waves, which then vibrate and break down the oxide film (thickness ≤ 2 μm) generated on the anode surface, exposing a fresh metal surface and promoting an increase in the electrochemical dissolution rate by 30%-50%.

[0090] The principle of multi-stage oblique tapered core wire: reaction mechanism: metal atoms lose electrons and are oxidized into metal ions (e.g., Fe → Fe). 2+ +2e - ), oxidants in the corrosive solution (such as H ), + NO3 - It gains electrons and is reduced. For example, iron corrodes in hydrochloric acid: Fe + 2HCl → FeCl₂ + H₂↑.

[0091] The workpiece core wire is mounted on the Y-axis servo motor via a fixed disk device. The PLC receives the diameter D value and the length L value of each segment of the core wire at each key position, calculates the required moving distance and speed for the diameter and the length of the inclined cone at each position, and then controls the servo motor to precisely control the speed and distance of the anode core wire's up and down movement, as well as the reaction time of the workpiece in the corrosive liquid, thereby achieving the reduction of material at each position of the anode core wire and the length of each inclined cone, etc.

[0092] Determining the servo motor moving speed of the anode core wire: After the parameters such as corrosion solution concentration, temperature, ultrasonic power, and core wire raw materials have been determined, the core wire radius grinding speed v_grind is first tested by trial-running the machine under these parameter settings. After determining v_grind, the required servo motor moving speed for any stage of the oblique tapered core wire can be calculated based on the slope a of the wire radius of each oblique tapered segment in the required multi-stage oblique tapered core wire (automatically calculated by r=a*l+b from the diameter D input by the PCL and the length L of each stage, where r is the wire radius and l is the wire length position) and the number of repeated grinding times n of the oblique tapered surface. The servo motor moving speed v is calculated by the following relationship:

[0093]

[0094] The pulse power supply system adopts a high-frequency pulse power supply (output voltage adjustable from 0-60V, frequency resolution 1kHz), and has bipolar pulse function (forward pulse width 5-50μs, reverse pulse width 1-10μs). The average current density (5-20A / cm²) is controlled by dynamically adjusting the duty cycle (20%-80%). 2 This achieves a balance between material removal rate and precision.

[0095] Electrode system:

[0096] Anode; nerve microwire core wire, fixed by a conductive clamp, which integrates a rotary drive device (speed 0-2000r / min, accuracy ±1r / min).

[0097] Cathode electrode; A ring-shaped copper tube electrode (inner diameter 1-5mm), which is then bent into a 5-50mm diameter arc-shaped electrode and coaxially fitted around the core wire, forming a ring-shaped electric field with the anode core wire. This homogenizes the edge electric field distribution and reduces the rounded corner effect at the machining edges. The inner ring of the arc-shaped electrode has 0.4mm diameter holes evenly distributed at 1mm intervals. Grinding fluid (including but not limited to acids, alcohols, etc.) can flow through these holes to form a return channel. Its main function is to accelerate grinding efficiency and create a physical attraction between the anode and cathode electrodes.

[0098] Electrolyte circulation system:

[0099] Electrolyte formulation: Ethanol and deionized water are mixed in a volume ratio of 1:1, with the addition of 4% NaCl and 0.5% sodium dodecyl sulfate (SDS). The conductivity is controlled at 15-25 mS / cm, and the surface tension is ≤30 mN / m to ensure that the electrolyte can quickly penetrate into the tiny processing gaps (5-50 μm).

[0100] Filtration circulation loop: A centrifugal pump (flow rate 5-10L / min) drives the electrolyte through three-stage filtration (5μm filter element → activated carbon adsorption → 0.22μm microporous membrane) to remove processing products (metal ions, wear debris) and maintain electrolyte cleanliness.

[0101] Motion control system:

[0102] Three-axis precision displacement stage (X / Y / Z axis positioning accuracy ±1μm, repeatability ±0.5μm): X-axis controls the radial feed of the tool electrode (resolution 0.1μm), Y-axis controls the position of the auxiliary electrode, and Z-axis controls the axial movement of the core wire (feed speed 0.01-1mm / min).

[0103] Vibration device: Axial high-frequency vibration (amplitude ±2μm, frequency 50-200Hz) is superimposed on the tool electrode to disrupt the concentration polarization in the processing gap and promote product discharge.

[0104] Online monitoring module:

[0105] The current sensor (accuracy ±0.1% FS) collects the processing current in real time and dynamically adjusts the pulse parameters through a fuzzy control algorithm. When the current fluctuation exceeds ±5%, the voltage is automatically compensated.

[0106] A microscopic vision system (magnification 200-1000x) monitors the surface morphology of the core wire online, and a laser micrometer (accuracy ±1μm) provides real-time feedback on the diameter, forming a closed-loop control.

[0107] Example 1 - Pulse Electrochemical Grinding:

[0108] Core wire clamping: Fix both ends of the core wire to be processed to the conductive clamp and adjust the coaxiality to a deviation of <5μ.

[0109] Electrode alignment: The offset between the tool electrode and the core wire is calibrated using a visual positioning system (target value 0-10μm) to ensure that the anode core wire is centered on the arc-shaped cathode electrode.

[0110] Parameter settings: Based on the core wire material and core wire structure:

[0111] like Figure 8 and Figure 9 Multi-stage grinding of nickel-titanium shape memory alloy core wire with a diameter of 0.30mm.

[0112] The grinding equipment is equipped with a PLC computer box, such as Figure 10 and Figure 11 .

[0113] Starting from the input D0 position, calculate the corresponding device control parameters for L0-L6 and D0-D6 as shown in the table below (for the straight, equal-diameter section, the movement is constant speed; for the variable-diameter inclined cone section, the servo motor will subdivide the distance into 0-300 equal parts and the movement is variable speed).

[0114] Example 2 - Direct oxidation-reduction reaction grinding method using corrosive liquid:

[0115] Core wire clamping: Fix the non-machined end of the core wire to be processed to the core wire fixing plate, and lock the 5mm length of the machined end to the counterweight nut. Adjust the coaxiality to a deviation of <10μm.

[0116] Solution tank alignment: Use a visual positioning system to calibrate the eccentricity between the tool electrode and the core wire (target value 0.1-1mm) to ensure that the core wire is centered in the corrosion solution tank.

[0117] Grinding fluid (including but not limited to acids, alcohols, etc.): The formulation is based on the different metal materials, such as nickel-titanium shape memory alloy;

[0118] Hydrofluoric acid (HF): 1%~15% (volume ratio). The higher the concentration, the faster the corrosion rate, but the risk of excessive corrosion must be balanced.

[0119] Nitric acid (HNO3): 5%~40% (volume ratio), used as an oxidant to inhibit hydrogen embrittlement and adjust corrosion selectivity 38.

[0120] Pure water: the remainder, used to control the intensity and rate of the reaction.

[0121] Parameter settings: Based on the core wire material and core wire structure:

[0122] like Figure 12 and Figure 13 Multi-stage grinding of nickel-titanium shape memory alloy material with a 0.30mm diameter core wire;

[0123] like Figure 14 The grinding device has the ability to precisely control displacement;

[0124] Starting from the input D0 position, calculate L0-L6. The corresponding device control parameters for D0-D6 are shown in the table below (for the straight, equal-diameter section, the movement is constant speed; for the variable-diameter inclined cone section, the servo motor will subdivide the distance into 0-300 equal parts and the movement is variable speed).

[0125] like Figure 15 Starting from the input D0 position, calculate L0-L6. The corresponding device control parameters for D0-D6 are shown in the table below (for the straight, equal-diameter section, the movement is constant speed; for the variable-diameter inclined cone section, the servo motor will subdivide the distance into 0-300 equal parts and move at variable speed).

[0126] It should be noted that parts have a lifespan and can be replaced during regular maintenance when they no longer meet performance requirements. Deterioration in performance due to prolonged use of parts is not a design defect of this application.

[0127] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An electrochemical grinding apparatus for a multi-stage, multi-shaped guide wire mandrel, comprising a frame (1), characterized in that, A laser measuring instrument (2) is mounted on the surface of the frame (1). A moving mechanism (3) is provided on the surface of the frame (1). A fixing mechanism (4) is provided on the surface of the moving mechanism (3). An ultrasonic water tank (5) is mounted on the surface of the frame (1). An electrolysis mechanism (6) is provided inside the ultrasonic water tank (5). A power supply (7) is mounted on the surface of the frame (1). The positive and negative terminals of the power supply (7) are electrically connected to a positive wire (8) and a negative wire (9), respectively. A liquid storage tank (10) is installed inside the frame (1). An electrolyte filter element (11) is mounted on the surface of the liquid storage tank (10). A circulating water pump (12) is mounted on the surface of the electrolyte filter element (11). A return pipe (13) is connected to the surface of the liquid storage tank (10).

2. The electrochemical grinding device for a multi-stage, multi-shape guide wire mandrel according to claim 1, characterized in that, The moving mechanism (3) includes a transverse guide rail (14) mounted on the surface of the frame (1), a first motor (15) mounted on the surface of the transverse guide rail (14), a vertical guide rail (16) mounted on the surface of the transverse guide rail (14), and a second motor (17) mounted on the top of the vertical guide rail (16).

3. The electrochemical grinding device for a multi-stage, multi-shaped guide wire mandrel according to claim 2, characterized in that, The fixing mechanism (4) includes a first fixing plate (18), which is mounted on the surface of the vertical guide rail (16) and the surface of the first fixing plate (18) is electrically connected to one end of the positive conductor (8). A first guide wire (19) is mounted on the surface of the first fixing plate (18), and a first gravity drop (20) is mounted on the bottom of the first guide wire (19).

4. The electrochemical grinding apparatus for a multi-stage, multi-shaped guide wire mandrel according to claim 2, characterized in that, The fixing mechanism (4) includes a second fixing plate (21), which is mounted on the surface of the vertical guide rail (16). A third motor (22) is mounted on the surface of the second fixing plate (21). The output end of the third motor (22) is connected to a first gear (23) via a coupling. A turntable clamp (24) is mounted on the inner wall of the second fixing plate (21). A second guide wire (25) is mounted on the bottom of the turntable clamp (24). A second gravity weight (26) is mounted on the bottom of the second guide wire (25). A first conductive wheel (27) is mounted on the top of the turntable clamp (24). A second gear (28) is installed at the bottom. A belt (29) is connected to the surface of the second gear (28) and the first gear (23). A conductive wheel support frame (30) is installed on the surface of the second fixed disk (21). The surface of the conductive wheel support frame (30) is electrically connected to the positive wire (8). A conductive central shaft (31) is installed inside the conductive wheel support frame (30). A second conductive wheel (32) is installed on the surface of the conductive central shaft (31). The surfaces of the first conductive wheel (27) and the second conductive wheel (32) are in contact. A spring (33) is installed between the conductive wheel support frame (30) and the second fixed disk (21).

5. The electrochemical grinding apparatus for a multi-stage, multi-shape guide wire mandrel according to claim 1, characterized in that, The electrolysis mechanism (6) includes a first fixed base (40), which is installed inside the ultrasonic water tank (5). The first fixed base (40) is installed inside the first fixed base (40), and the bottom of the first electrolyte tank (34) is connected to the circulating water pump (12). The top of the first motor (15) tank is connected to one end of the return pipe (13). The inner wall of the electrolyte tank is equipped with a first electrode (35), and the first electrode (35) is electrically connected to the negative electrode wire (9).

6. The electrochemical grinding apparatus for a multi-stage, multi-shape guide wire mandrel according to claim 1, characterized in that, The electrolysis mechanism (6) includes a second fixed base (36), which is installed inside the ultrasonic water tank (5). A second electrolyte tank (37) is installed inside the second fixed base, and the surface of the second electrolyte tank (37) is connected to one end of the return pipe (13). The top of the electrode tank is connected to the circulating water pump (12). A second electrode (38) is installed on the inner wall of the second electrolyte tank (37), and the surface of the second electrode (38) is electrically connected to the negative electrode wire (9). A third electrode (39) is installed inside the second electrode (38).

7. A pulse electrochemical grinding method for a multi-stage, multi-shape guide wire mandrel, employing the electrochemical grinding apparatus for a multi-stage, multi-shape guide wire mandrel as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Clamping and alignment: Fix the guide wire mandrel as the anode to the fixing mechanism (4), and use a gravity drop at the bottom to straighten the mandrel. Adjust the coaxiality of the mandrel and the electrode of the electrolysis mechanism (6) through the moving mechanism (3) so that the eccentricity deviation is <10μm. S2, Electrolyte circulation supply: The circulating water pump (12) sends the electrolyte in the liquid storage tank (10) through the electrolyte filter element (11) for three-stage filtration and then into the electrolyte tank of the electrolysis mechanism (6). The return pipe (13) simultaneously realizes the electrolyte return circulation. S3, Pulse electrochemical dissolution: Power supply (7) supplies pulsed DC current to the anode core and cathode electrode. The core surface undergoes metal dissolution and oxidation reaction in the electrolyte. The ultrasonic water tank (5) breaks the passivation film on the core surface through high-frequency vibration. S4. Multi-stage taper forming: The PLC system receives the preset diameter and length parameters of the mandrel, calculates the moving distance and speed, and controls the moving mechanism (3) to precisely adjust the axial moving speed of the mandrel. The straight section moves at a constant speed and the oblique cone section moves at a variable speed and subdivided speed to complete the multi-stage gradual taper processing. S5. Online closed-loop detection: The laser measuring instrument (2) collects the spindle diameter data in real time, dynamically compensates the processing parameters, and ensures the accuracy of diameter control.

8. The pulse electrochemical grinding method for a multi-stage, multi-shape guide wire mandrel according to claim 7, characterized in that, In step S3, the peak voltage of the pulsed DC current is 10-50V, the frequency is 10-100kHz, and the average current density is 5-20A / cm²; the ultrasonic frequency is 40-80kHz, the power is 10-30W / cm², and the material removal rate is increased by 30%-50% after the passivation film is broken.

9. The pulse electrochemical grinding method for a multi-stage, multi-shape guide wire mandrel according to claim 7, characterized in that, The electrolyte is a mixture of ethanol and deionized water in a 1:1 volume ratio, with the addition of 3%-5% NaCl and 0.5% sodium dodecyl sulfate, and the conductivity is controlled at 15-25 mS / cm.

10. A chemical grinding method for a multi-stage, multi-shaped guide wire mandrel, employing the electrochemical grinding apparatus as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Core wire clamping and positioning: Fix the non-machined end of the core wire to the fixed plate, assemble the gravity weight at the machined end, and adjust the coaxiality of the core wire to a deviation of <10μm. S2. Preparation of etching solution: For nickel-titanium alloy core wire, prepare an etching solution containing 1%~15% hydrofluoric acid and 5%~40% nitric acid. S3. Chemical dissolution processing: The core wire is immersed in the corrosion solution to undergo an oxidation-reduction reaction. Ultrasonic waves are used to help break the passivation film on the surface of the core wire and control the corrosion reaction time. S4. Variable Diameter Size Control: The servo motor moves the core wire at varying speeds according to preset inclined cone diameter and length parameters to achieve multi-stage variable diameter processing. S5. Product Filtration and Circulation: The electrolyte circulation system continuously filters the processed products, maintaining the cleanliness of the etchant and the stability of the process.

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