Flexible bendable rotary grinding drill bit for plaque in coronary artery cavity and machining method of flexible bendable rotary grinding drill bit

Abstract

The invention discloses a flexible bendable rotary grinding drill bit for coronary artery intracavitary plaques and a machining method of the flexible bendable rotary grinding drill bit, and relates to the technical field of medical instruments.The machining method comprises the following steps that a drill bit base body is selected, and a wear-resistant coating material is prepared; the drill bit is designed to be of a multi-section structure formed by connecting a plurality of miniature spherical joints. Cutting the material into multiple sections by using precise laser, and performing electrochemical polishing; smooth spherical joints are machined at the joints of all the sections of the drill bit through the micro-forging technology; firmly covering a superhard wear-resistant coating on the surface of the drill bit; the drill bit is subjected to vacuum heat treatment, and the hyperelastic performance of the material is stabilized; the processed drill bit core is connected with a flexible driving shaft; and a finished product is thoroughly cleaned and sterilized, and packaging is completed in a sterile environment. Through material selection and structural design, the drill bit has flexibility and bendability, and can smoothly pass through tortuous blood vessels to effectively grind calcified plaques.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical devices, and particularly relates to a flexible and bendable rotary grinding drill bit for coronary artery intraluminal plaque and a processing method thereof. BACKGROUND

[0002] The rotary grinding drill bit is a miniature rotary instrument used in interventional cardiology to treat calcified lesions. It abrades the calcified plaque on the blood vessel wall through a high-speed rotating grinding head to restore the coronary artery blood flow. The conventional coronary artery rotary grinding drill bit is of a rigid structure. When treating tortuous calcified lesions, especially the calcified lesions at the distal end of the right coronary artery (RCA) or the distal end of the left circumflex branch (LCX), it is difficult to pass through the curved blood vessels, resulting in the problem of "grinding failure". A drill bit with a diameter that is too large is prone to cause no-reflow phenomenon, and a drill bit with a diameter that is too small is not fully ground. Therefore, the following scheme is proposed to solve the above problems. SUMMARY

[0003] The present application aims to provide a flexible and bendable rotary grinding drill bit for coronary artery intraluminal plaque and a processing method thereof. Through material selection and structure design, the drill bit has flexibility and bendability, can smoothly pass through the tortuous blood vessels, and effectively grind the calcified plaque, solving the problem that the existing rotary grinding drill bit is of a rigid structure and is difficult to pass through the curved blood vessels when treating tortuous calcified lesions.

[0004] To solve the above technical problems, the present application is realized by the following technical scheme:

[0005] The present application is a flexible and bendable rotary grinding drill bit for coronary artery intraluminal plaque, which comprises a drill bit base, a wear-resistant coating covering the surface of the drill bit base, and a flexible drive shaft connected to one end of the drill bit base.

[0006] The drill bit base is made of a nickel-titanium alloy wire, and the composition of the nickel-titanium alloy is: nickel 55%-56%, titanium balance, and 0.5%-1.0% chromium and 0.1%-0.3% iron are additionally added to the nickel-titanium alloy. The diameter of the nickel-titanium alloy wire is 0.5mm-1.0mm.

[0007] The drill bit base is of a multi-section structure, and the length of each section is 0.5mm-1.0mm. The total length of the drill bit base is 10mm-20mm. The adjacent two sections are detachably connected through a micro spherical joint. The diameter of the micro spherical joint is 0.3mm-0.5mm, and the micro spherical joint allows the drill bit base to bend to 90 degrees in multiple directions.

[0008] A spiral groove is formed on the outer surface of the drill bit base. The depth of the spiral groove is 0.05mm-0.1mm, the width is 0.1mm-0.2mm, and the distance between adjacent grooves is 0.2mm-0.3mm.

[0009] The wear-resistant coating is filled in the spiral groove and covers the outer surface of the drill bit base, and the raw material of the wear-resistant coating is nano-diamond powder or silicon carbide powder;

[0010] The purity of the nano-diamond powder is ≥99.9%, the purity of the silicon carbide powder is ≥99.5%, and the particle size of the nano-diamond powder or silicon carbide powder ranges from 0.1 μm to 10 μm, and the thickness of the wear-resistant coating is 5 μm-10 μm;

[0011] The end of the drill bit base away from the flexible driving shaft is hemispherical, and the diameter of the hemisphere is consistent with the diameter of the drill bit base; the flexible driving shaft is woven by a plurality of stainless steel wires, the diameter of the stainless steel wires is 0.05 mm-0.1 mm, the outer part of the flexible driving shaft is covered with a polytetrafluoroethylene coating, the thickness of the polytetrafluoroethylene coating is 0.1 mm-0.2 mm, and the diameter of the flexible driving shaft is 0.8 mm-1.5 mm.

[0012] Further, the nickel-titanium alloy wire is sequentially ultrasonically cleaned with acetone and deionized water for 10 minutes before processing to remove surface oxides and impurities.

[0013] Further, the outer surface of the micro-spherical joint is mechanically polished, the diamond polishing paste with a particle size of 0.5 μm-1.0 μm is used during polishing, the polishing is performed on a micro-polishing machine at a speed of 1000 rpm-2000 rpm for 5 min-10 min, and the polishing paste is removed by ethanol cleaning after polishing.

[0014] Further, the drill bit base and the flexible driving shaft are fixed by laser welding, and the parameters of laser welding are: power 20 W-30 W, pulse time 0.1 s-0.5 s, and focal point diameter 0.1 mm.

[0015] A processing method of a flexible and bendable rotary grinding drill bit for coronary artery intraluminal plaque, comprising the following steps:

[0016] S1, material preparation: selecting the nickel-titanium alloy wire with the components and diameter as claimed in claim 1 as the drill bit base raw material, ultrasonically cleaning the nickel-titanium alloy wire with acetone for 10 minutes and then ultrasonically cleaning it with deionized water for 10 minutes to remove surface oxides and impurities; selecting the nano-diamond powder or silicon carbide powder with the purity and particle size as claimed in claim 1 as the wear-resistant coating raw material, and storing the wear-resistant coating raw material in a dry environment with a relative humidity of ≤30%;

[0017] S2, drill bit structure design: design the multi-section drill bit base structure, spiral groove structure and hemispherical tip structure according to claim 1, and design the micro spherical joint structure matched with the drill bit base;

[0018] S3, base forming: cutting the nickel-titanium alloy wire after cleaning in step S1 by using a fiber laser to form a multi-section drill bit base; the laser cutting parameters are set as: power 50W-100W, cutting speed 10mm / s-20mm / s, frequency 1kHz-5kHz, spot diameter 0.01mm-0.02mm, and argon gas with a flow rate of 5L / min-10L / min is used as the protective gas during the cutting process; after the cutting is completed, electrochemical polishing is performed on the drill bit base: using a mixed solution with a volume ratio of phosphoric acid to sulfuric acid of 3:1 as the polishing liquid, setting the polishing voltage to 5V-10V and the polishing time to 30s-60s, and then rinsing with deionized water and drying at 60℃-80℃;

[0019] S4, spherical joint manufacturing: micro forging is performed on both ends of each section of the drill bit base formed in step S3 by using a micro stamping machine to form a micro spherical joint; the micro forging parameters are set as: stamping pressure 0.5MPa-1.0MPa, temperature 200℃-300℃, and holding time 10s-20s, and the mold used for micro forging is tungsten carbide material; mechanical polishing is performed on the outer surface of the micro spherical joint: using diamond polishing paste with a particle size of 0.5μm-1.0μm, polishing at a speed of 1000rpm-2000rpm on a micro polishing machine for 5min-10min, and then rinsing with ethanol to remove the residual polishing paste;

[0020] S5, application of wear-resistant coating: when nano-diamond powder is selected as the wear-resistant coating raw material, a wear-resistant coating is prepared by using chemical vapor deposition method: the drill bit base treated in step S4 is placed in a chemical vapor deposition reaction chamber, heated to 800℃-1000℃, the pressure in the reaction chamber is maintained at 1kPa-10kPa, a mixed gas with a volume ratio of methane to hydrogen of 1:10 is introduced, and the deposition is performed for 2h-4h to make the thickness of the wear-resistant coating reach 5μm-10μm;

[0021] when silicon carbide powder is selected as the wear-resistant coating raw material, a wear-resistant coating is prepared by using physical vapor deposition method: the deposition temperature is set to 400℃-600℃, the deposition pressure is set to 0.1Pa-1 Pa, the sputtering power is set to 500W-1000W, the deposition is performed for 1h-2h, and after the deposition is completed, the coating surface is slightly polished for 2min-3min by using diamond polishing paste with a particle size of 0.5μm-1.0μm to remove protruding particles;

[0022] S6, heat treatment: the drill bit base coated with wear-resistant coating in step S5 is subjected to vacuum heat treatment: the drill bit base is placed in a vacuum furnace, the vacuum furnace is vacuumed to less than or equal to 10-3 Pa, heated to 500-550 DEG C and kept for 30-60 min; then nitrogen is introduced as a cooling medium, and the cooling rate is greater than or equal to 50 DEG C / min, and the drill bit base is cooled to room temperature; after cooling, the drill bit base is subjected to aging treatment: kept at 400 DEG C for 10 min, and then naturally cooled to room temperature;

[0023] S7, final assembly: the flexible drive shaft with the structure of claim 1 is selected, and the drill bit base treated in step S6 is connected with the flexible drive shaft by using a laser welding machine; the laser welding parameters are as follows: power 20-30 W, pulse time 0.1-0.5 s, and focal point diameter 0.1 mm; after welding, the connection strength is detected by using a tension testing machine to ensure that the connection part is not loose;

[0024] S8, cleaning and packaging: the rotary abrasive drill bit assembled in step S7 is placed in an ultrasonic cleaning machine, a mixed solution with a volume ratio of deionized water to ethanol of 1:1 is used as a cleaning liquid, the cleaning frequency is set to 40 kHz, and the cleaning time is set to 10 min; after cleaning, the rotary abrasive drill bit is washed with pure water for three times, and then dried at 60-80 DEG C; the dried rotary abrasive drill bit is subjected to ethylene oxide sterilization, and then packaged in a medical-grade Tyvek bag in a hundred-level sterile environment, and the drill bit model, specification, production batch number, production date and sterilization date are marked on the package.

[0025] Further, the purity of the argon in step S3 is greater than or equal to 99.99%.

[0026] Further, when the physical vapor deposition method is used to prepare the silicon carbide wear-resistant coating in step S5, the sputtering target is silicon carbide with a purity greater than or equal to 99.9%.

[0027] Further, the parameters of ethylene oxide sterilization in step S8 are as follows: sterilization temperature 30-50 DEG C, ethylene oxide concentration 600-800 mg / L, sterilization time 4-6 h, and ventilation analysis for 24 h after sterilization.

[0028] The present application has the following beneficial effects:

[0029] 1、The flexible and bendable rotary grinding drill head for coronary artery intraluminal plaque and its processing method, by adopting a flexible base material and a multi-section structure design, the rotary grinding drill head has good bending performance and compliance, can adapt to the anatomical path of tortuous blood vessels, and can reduce mechanical stimulation and potential damage to the blood vessel wall when the drill head travels in the blood vessel, thereby reducing the resistance in operation; this design avoids the problem that the traditional rigid drill head is easy to jam or cannot reach the curved position, improves the controllability and passing efficiency of the instrument in complex lesions; at the same time, the flexibility of the drill head helps to maintain the natural shape of the blood vessel, reduces the risk of blood vessel spasm or perforation caused by the rigidity of the instrument, and creates safer conditions for subsequent treatment; overall, the method optimizes the structure and material, and improves the applicability and operation fluency of the drill head in a narrow and tortuous environment.

[0030] 2、The preparation method of the present application can make the drill head have excellent grinding capacity and durability while maintaining flexibility; the combination of the coating material and the base enhances the hardness and wear resistance of the drill head surface, so that it can continuously and effectively grind when contacting the calcified plaque, without premature passivation or failure; the multi-section design of the drill head allows stress dispersion during grinding, avoiding local excessive wear and prolonging the service life of the instrument; in addition, this structure ensures the stability and uniformity of the grinding action, which helps to achieve more consistent plaque removal effect in complex lesions, reduces the need for repeated operations due to insufficient grinding, and improves the overall treatment efficiency.

[0031] Of course, implementing any product of the present application does not necessarily require all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The flowchart of the flexible and bendable rotary grinding drill head for coronary artery intraluminal plaque and its processing method. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0035] Please refer toFigure 1 The present application is a flexible and bendable rotary grinding drill bit for coronary artery intraluminal plaque and its processing method, including the following steps:

[0036] Step S1, material preparation

[0037] Select the base material: use Nitinol wire as the drill bit base, with a composition of 55-56% nickel, titanium balance, and the addition of 0.5-1.0% chromium and 0.1-0.3% iron to enhance corrosion resistance. The wire diameter is 0.5-1.0 mm, with superelasticity and biocompatibility. The wire surface is pre-cleaned to remove oxides and impurities, and is ultrasonically cleaned with acetone and deionized water for 10 minutes.

[0038] Prepare the wear-resistant coating material: choose nano-diamond powder or silicon carbide powder as the coating material, with a particle size range of 0.1-10 microns. The purity of nano-diamond powder is ≥99.9%, and the purity of silicon carbide powder is ≥99.5%. The coating material is stored in a dry environment to avoid moisture.

[0039] Step S2, drill bit structure design

[0040] Multi-section design: the drill bit is designed as a multi-section structure, each section is 0.5-1.0 mm long, and the total length is customized according to application requirements. The sections are connected by micro spherical joints, with a diameter of 0.3-0.5 mm, allowing the drill bit to bend 90 degrees in multiple directions to adapt to the tortuosity of blood vessels.

[0041] Surface structure design: the drill bit surface is designed with spiral grooves, with a depth of 0.05-0.1 mm and a width of 0.1-0.2 mm for embedding wear-resistant coating materials. The groove spacing is 0.2-0.3 mm to optimize grinding efficiency and flexibility. The drill bit tip is hemispherical with a diameter consistent with the drill bit body, reducing damage to the vessel wall.

[0042] Step S3, base forming

[0043] Laser cutting: use a precision laser cutting machine (such as a fiber laser) to cut the Nitinol wire to form a multi-section structure. The laser cutting parameters are set as follows: power 50-100 W, cutting speed 10-20 mm / s, frequency 1-5 kHz, and spot diameter 0.01-0.02 mm. Argon gas is used as a protective gas during cutting at a flow rate of 5-10 L / min to prevent material oxidation.

[0044] Electrochemical polishing: after cutting, the drill bit base is electrochemically polished to remove burrs and sharp edges. The polishing solution is a mixture of phosphoric acid and sulfuric acid (volume ratio 3:1), with a voltage setting of 5-10 V and a polishing time of 30-60 seconds. After polishing, rinse with deionized water and dry.

[0045] Step S4, Ball Joint Manufacturing

[0046] Micro Forging Technique: At both ends of each segment, micro forging is performed using a micro punch press to form the ball joint. The punch pressure is set to 0.5-1.0 MPa, the temperature is 200-300°C, and the holding time is 10-20 seconds. The mold is made of tungsten carbide material to ensure the precision and smoothness of the ball joint.

[0047] Surface Polishing: The surface of the ball joint is mechanically polished using diamond polishing paste (particle size 0.5-1.0 microns) on a micro polishing machine at a speed of 1000-2000 rpm for 5-10 minutes. After polishing, the residual polishing paste is removed with ethanol cleaning.

[0048] Step S5, Application of Wear-Resistant Coating

[0049] Chemical Vapor Deposition (CVD): A nano-diamond coating is applied to the drill bit surface using the CVD method. The drill bit is placed in the CVD reaction chamber and heated to 800-1000°C, with a pressure maintained at 1-10 kPa. A mixture of methane and hydrogen gas (flow ratio 1:10) is introduced, and the deposition time is 2-4 hours. The coating thickness is controlled at 5-10 microns to ensure uniform coverage.

[0050] Alternative Coating Method: If a silicon carbide coating is used, a physical vapor deposition (PVD) method can be used. PVD parameters: temperature 400-600°C, pressure 0.1-1 Pa, sputtering power 500-1000 W, time 1-2 hours. After coating, the drill bit surface is lightly polished to remove protruding particles.

[0051] Step S6, Heat Treatment

[0052] Vacuum Heat Treatment: The coated drill bit is heat treated to optimize the super-elasticity and shape memory effect of the nickel-titanium alloy. The heat treatment is carried out in a vacuum furnace with a vacuum degree ≤10^-3 Pa, a temperature of 500-550°C, and a time of 30-60 minutes. Subsequently, it is rapidly cooled to room temperature at a cooling rate ≥50°C / min using nitrogen as the cooling medium.

[0053] Performance Stabilization: After heat treatment, the drill bit is subjected to aging treatment at 400°C for 10 minutes to further stabilize the material performance.

[0054] Step S7, Final Assembly

[0055] Connecting the driving shaft: connecting the drill bit to the flexible driving shaft. The driving shaft is made of multiple strands of stainless steel wire (diameter 0.05-0.1 mm) braided together, with an outer coating of polytetrafluoroethylene (PTFE) with a thickness of 0.1-0.2 mm. The driving shaft has a diameter of 0.8-1.5 mm and a length that is customized according to clinical needs.

[0056] Laser welding: using a laser welding machine to connect the drill bit base to the driving shaft. Welding parameters: power 20-30 W, pulse time 0.1-0.5 seconds, focus diameter 0.1 mm. After welding, check the connection strength to ensure that there is no looseness.

[0057] Step S8, cleaning and packaging

[0058] Ultrasonic cleaning: place the assembled drill bit in an ultrasonic cleaning machine, use a mixture of deionized water and ethanol (volume ratio 1:1), frequency 40 kHz, clean for 10 minutes. After cleaning, rinse with pure water and dry.

[0059] Sterile packaging: after drying, the drill bit is sterilized with ethylene oxide, and then packaged in a sterile environment. The packaging material is a medical-grade Tyvek bag, and the product information and sterilization date are marked.

[0060] The specific application of this embodiment is:

[0061] Example 1: preparation of a flexible rotary abrasive drill bit (nano-diamond coating) for right coronary artery (RCA) distal tortuous calcified lesions.

[0062] This embodiment aims to prepare a flexible and bendable rotary abrasive drill bit that adapts to the RCA distal "shepherd's crook" anatomical variation blood vessels. The total length of the drill bit is 15 mm, and it is used to treat tortuous calcified vascular lesions with a diameter of 2.5-3.0 mm. The specific steps are as follows:

[0063] Step S1, material preparation

[0064] Base material preparation: select nickel-titanium alloy (Nitinol) wire as the drill bit base raw material, with the chemical composition accurately controlled as follows: nickel 55.5%, titanium 43.5%, chromium 0.8%, and iron 0.2% (all by mass fraction), and the wire diameter is 0.8 mm. Cut the wire into 20 mm long segments, and sequentially place them in acetone solution and deionized water for ultrasonic cleaning, with each step of cleaning lasting 10 minutes (ultrasonic frequency 40 kHz). After cleaning, dry them in a 70°C air drying oven for 30 minutes to remove surface oxides and oil stains and impurities.

[0065] Preparation of wear-resistant coating material: Select nanodiamond powder as the coating raw material, with a purity of 99.95% and a particle size distribution of 0.5-5 microns (detected by laser particle size analyzer). Store the nanodiamond powder in a dry nitrogen environment with a relative humidity of ≤25% to avoid moisture aggregation.

[0066] Step S2, design of drill bit structure

[0067] Design of multi-section base structure: Each section of the base is 0.8 mm long, with a total of 18 sections (total length 14.4 mm, with a 0.6 mm reserved for connection with the drive shaft); the sections are connected by micro spherical joints with a diameter of 0.4 mm, designed to allow the drill bit to bend up to 90° in three-dimensional directions.

[0068] Design of surface spiral grooves: Groove depth 0.08 mm, width 0.15 mm, adjacent groove spacing 0.25 mm, groove axial spiral angle 30°, used for embedding wear-resistant coatings and optimizing grinding and chip removal efficiency; the drill bit tip is designed as a hemisphere with a diameter consistent with the base (0.8 mm) to reduce the risk of scratching the blood vessel wall.

[0069] Step S3, base forming

[0070] Laser cutting: Use a fiber laser with model IPG YLR-100 to cut the dried nickel-titanium alloy wire, with cutting parameters set as: laser power 80 W, cutting speed 15 mm / s, pulse frequency 3 kHz, and spot diameter 0.015 mm. During the cutting process, pure argon gas with a purity of 99.995% is introduced through a coaxial nozzle at a flow rate of 8 L / min to form a protective atmosphere and prevent the base surface from oxidizing.

[0071] Electrochemical polishing: Configure the polishing solution (phosphoric acid:sulfuric acid = 3:1, volume ratio), fix the cut multi-section base on a titanium alloy hanger, and place it in the polishing tank. Set the polishing voltage to 8 V, the current density to 1.5 A / dm 2 , and the polishing time to 45 seconds. After polishing, immediately rinse with deionized water for 3 times (1 minute each time), and then dry in a 70°C vacuum drying oven for 20 minutes.

[0072] Step S4, spherical joint manufacturing

[0073] Micro forging: Use a micro punch with model F-30, matched with a spherical die made of tungsten carbide (cavity diameter 0.4 mm), to perform micro forging on both ends of each section of the base. Set the punch pressure to 0.8 MPa, the die heating temperature to 250°C, and the pressure holding time to 15 seconds to ensure the formation of smooth spherical joints on the surface.

[0074] Surface polishing: Take the diamond polishing paste with a particle size of 1.0 microns (mixed with anhydrous ethanol in a ratio of 1:3 into a paste), apply it to the wool polishing disc of the micro-polishing machine (model MP-100), align the spherical joint with the polishing disc, set the rotation speed to 1500 rpm, and polish for 8 minutes. After polishing, clean with anhydrous ethanol for 5 minutes to remove residual polishing paste, and then vacuum dry.

[0075] Step S5, application of wear-resistant coating

[0076] Nanodiamond coating is prepared by chemical vapor deposition (CVD) method, the specific operation is as follows:

[0077] 1. Put the treated substrate into the hot wire CVD reaction chamber, seal and vacuum to 5x10^-4 Pa;

[0078] 2. Heat the reaction chamber to 900℃, introduce a mixture of methane and hydrogen gas (flow ratio 1:10), with methane flow rate 10sccm, hydrogen flow rate 100sccm, and maintain the reaction chamber pressure at 5kPa;

[0079] 3. Maintain the deposition time for 3 hours, monitor the coating thickness in real time by quartz crystal monitor, and ensure that the final coating thickness is 8 microns;

[0080] 4. After deposition, turn off the heating device and continue to introduce hydrogen until the reaction chamber temperature drops to below 200℃, then take out the drill bit substrate.

[0081] Step S6, heat treatment

[0082] Vacuum heat treatment: Put the coated drill bit substrate into the vacuum heat treatment furnace (model ZT-50), vacuum to 5x10^-4 Pa, heat to 520℃, and keep for 45 minutes; then introduce nitrogen gas with a purity of 99.999% as cooling medium, control the cooling rate at 60℃ / min, until the furnace temperature drops to room temperature.

[0083] Aging treatment: Transfer the cooled drill bit substrate to the box-type resistance furnace, keep at 400℃ for 10 minutes, then cut off the power and naturally cool to room temperature, to stabilize the super-elasticity of the nickel-titanium alloy and the coating adhesion.

[0084] Step S7, final assembly

[0085] Drive shaft preparation: Select multiple strands of 316L stainless steel wire (single wire diameter 0.08mm) to weave into a flexible drive shaft, with a weaving density of 80% and a shaft body diameter of 1.2mm; coat the outer surface of the drive shaft with a polytetrafluoroethylene (PTFE) coating, with a coating thickness of 0.15mm, and sinter and solidify at 380℃.

[0086] Laser welding: use pulse laser welding machine model JK-20 to butt joint the drill bit base and the drive shaft (butt joint gap ≤0.02mm), set the welding parameters: power 25W, pulse time 0.3 seconds, focus diameter 0.1mm, after welding, use 50 times microscope to observe the weld without cracks.

[0087] Strength detection: use micro tension testing machine to test the tensile strength of the connection part, test force 50N, keep for 10 seconds, the connection part is not loose or broken, which meets the strength requirement.

[0088] Step S8, cleaning and packaging

[0089] Ultrasonic cleaning: put the assembled drill bit into the ultrasonic cleaner (model KQ-500), add a mixture of deionized water and anhydrous ethanol (volume ratio 1:1), set the cleaning frequency to 40kHz and the cleaning time to 10 minutes; after cleaning, rinse with ultrapure water (resistivity ≥18.2MΩ·cm) for 3 times, each time for 2 minutes, and then dry in a vacuum drying oven at 80℃ for 30 minutes.

[0090] Sterile packaging: put the dried drill bit into an ethylene oxide sterilization cabinet, set the sterilization parameters: temperature 40℃, ethylene oxide concentration 700mg / L, relative humidity 60%, sterilization time 5 hours; after sterilization, ventilate for 24 hours (ambient temperature 25℃, ventilation volume 5m 3 / h), ensure that the residual amount of ethylene oxide is ≤10μg / g. Finally, in a hundred-level sterile clean room, put the drill bit into a medical-grade Tyvek bag (model TY-1073B), heat-seal package, and mark the product model (FM-15-08), production batch number (20240501), production date (May 1, 2024) and sterilization date (May 2, 2024).

[0091] Product performance verification:

[0092] The rotary grinding drill bit prepared in this example can smoothly pass through the simulated tortuous blood vessel model (bending angle 90°, curvature radius 5mm) without jamming; the grinding test is carried out on the simulated material of calcified plaque (hardness HV500), the rotating speed is 180000rpm, the grinding efficiency reaches 0.5mm 3 / min, and the coating does not fall off, and the blood vessel wall simulation material (silicone) has no scratches, which meets the requirements of clinical application.

[0093] Example 2: preparation of flexible rotary grinding drill bit for distal calcified lesions of left circumflex artery (LCX) (silicon carbide coating).

[0094] The total length of the drill bit prepared in this example is 12mm, which is suitable for tortuous blood vessels with a diameter of 2.0-2.5mm at the distal end of LCX, and silicon carbide coating is used to improve wear resistance, the specific steps are as follows:

[0095] Step S1, material preparation

[0096] Nickel-titanium alloy wire composition: nickel 55.0%, titanium 44.2%, chromium 0.6%, iron 0.2%, wire diameter 0.7mm;

[0097] Abrasion-resistant coating raw material: silicon carbide powder (purity 99.6%, particle size 1-8 microns), stored in a dry environment with relative humidity ≤30%.

[0098] Step S2, structure design

[0099] Multi-segment base, each segment length 0.7mm, total 17 segments (total length 11.9mm);

[0100] Micro-spherical joint diameter 0.35mm;

[0101] Helical groove: depth 0.06mm, width 0.12mm, pitch 0.22mm.

[0102] Step S5, application of abrasion-resistant coating (physical vapor deposition PVD method)

[0103] 1. Put the base into the magnetron sputtering PVD device (model JGP-450) and vacuumize to 5x10^-4Pa;

[0104] 2. Heat the base to 500°C, introduce argon gas (purity 99.999%), maintain vacuum degree 0.5Pa, perform ion cleaning (power 300W, time 10 minutes);

[0105] 3. Use silicon carbide target material with purity 99.9%, set sputtering power 800W, deposition time 1.5 hours, coating thickness 6 microns;

[0106] 4. After deposition, cool to room temperature, slightly polish the coating surface with 0.5 micron diamond polishing paste for 2 minutes to remove protruding particles.

[0107] Step S7, final assembly

[0108] Flexible drive shaft: 316L stainless steel wire single filament diameter 0.07mm, braided diameter 1.0mm, PTFE coating thickness 0.12mm;

[0109] Laser welding parameters: power 22W, pulse time 0.2 seconds.

[0110] Product performance verification:

[0111] The drill bit of the present embodiment has good passability in a simulated LCX distal tortuous blood vessel model (bend angle 85°, radius of curvature 4 mm); in the grinding test, the rotational speed is 160,000 rpm, the grinding efficiency is 0.4 mm / min, the coating bonding force is 50 MPa (cross-hatch method test), and the clinical use requirements are met. 3

[0112] Example 3: Preparation of flexible rotary abrasive drill bit (nano-diamond coating) for left circumflex branch (LCX) distal small tortuous calcified lesions;

[0113] The present embodiment aims to prepare a flexible and bendable rotary abrasive drill bit suitable for LCX distal small tortuous blood vessels with a diameter of 1.8-2.2 mm. The total length of the drill bit is 10 mm, and the focus is on optimizing the slimness and bending adaptability of the drill bit to cope with the complex anatomical structure of the LCX distal branch blood vessels. The specific steps are as follows:

[0114] Step S1, material preparation

[0115] Base material preparation: Selecting Nitinol wire as the drill bit base raw material, the chemical composition is accurately controlled as follows: nickel 55.8%, titanium 43.0%, chromium 0.9%, and iron 0.3% (all by mass fraction), and the wire diameter is 0.6 mm (suitable for small blood vessel channels). The wire is cut into 15 mm long segments, which are sequentially placed in acetone solution (analytical pure) and deionized water (resistivity ≥ 18.2 MΩ·cm) for ultrasonic cleaning, each step for 10 minutes (ultrasonic frequency 40 kHz, power 300 W). After cleaning, it is dried in a 65°C air drying oven for 25 minutes to completely remove the surface oxidation film, oil stains and dust impurities.

[0116] Preparation of wear-resistant coating material: Selecting nano-diamond powder as the coating raw material, its purity is 99.92%, and the particle size distribution is 0.3-3 microns (detected by dynamic light scattering instrument, D50 = 1.5 microns), avoiding large particle size powder blocking small grooves. The nano-diamond powder is stored in a dry inert gas (nitrogen) environment with a relative humidity of ≤28%, and the storage container is equipped with a drying agent (anhydrous calcium chloride) to prevent the powder from being damp and agglomerated.

[0117] Step S2, drill bit structure design

[0118] Designing a multi-segment base structure: each segment has a length of 0.6 mm, and there are 16 segments in total (total length 9.6 mm, reserving 0.4 mm for connection with the driving shaft); the segments are connected by micro spherical joints with a diameter of 0.3 mm (smaller than the previous two embodiments, reducing the space occupied in the blood vessel), and the design allows the drill bit to bend up to 90° in three-dimensional direction without jamming and rigid collision between adjacent segments.

[0119] ​Surface helical groove design: groove depth 0.05mm (adapt to small substrate diameter, avoid weakening the substrate strength), width 0.1mm, adjacent groove spacing 0.2mm, helical angle of groove along the substrate axial 25° (reduce the friction resistance of blood vessel wall when grinding); drill bit tip is hemispherical, diameter consistent with substrate (0.6mm), tip surface roughness Ra≤0.2μm, further reduce the risk of damage to the vascular endothelium.

[0120] Step S3, substrate forming

[0121] Laser cutting: use the fiber laser with the model Raycus RFL-C100 to cut the dried nickel-titanium alloy wire, and the cutting parameters are adjusted as follows: laser power 60W (to avoid high power causing the small wire to be fused), cutting speed 12mm / s, pulse frequency 2kHz, and spot diameter 0.012mm (to improve the cutting precision of small structures). During the cutting process, pure argon gas with a purity of 99.99% is introduced through a side blowing nozzle at a flow rate of 6L / min to form a local protective atmosphere and prevent the substrate from being oxidized and discolored.

[0122] Electrochemical polishing: configure the polishing solution (phosphoric acid:sulfuric acid = 3:1, volume ratio, both are analytical pure), fix the cut multi-section substrate on a polytetrafluoroethylene hanger (to avoid metal hanger pollution), and put it into the polishing tank. Set the polishing voltage to 6V, the current density to 1.2A / dm 2 (reduce the current to avoid over-corrosion of the small substrate), and the polishing time to 30 seconds. After polishing, immediately rinse with deionized water for 4 times (30 seconds each time), and then dry in a 65℃ vacuum drying oven (vacuum degree 5×10^-2Pa) for 15 minutes to prevent corrosion caused by residual polishing solution on the substrate surface.

[0123] Step S4, spherical joint manufacturing

[0124] Micro forging: use the MiniPress-20 micro precision punch machine, and match the spherical mold made of tungsten carbide (cavity diameter 0.3mm, surface roughness Ra≤0.05μm) to micro forge the two ends of each substrate. Set the punch pressure to 0.6MPa (adapt to small substrate, avoid excessive deformation), mold heating temperature to 220℃, and pressure holding time to 12 seconds to ensure that the spherical joint is formed completely and the surface is smooth without depression.

[0125] Surface polishing: Take the diamond polishing paste with a particle size of 0.5 microns (mixed with anhydrous ethanol in a ratio of 1:4 to form a thin paste to avoid clogging of the small joint gap), apply it to the ultra-fine fiber polishing disc of the micro-polishing machine (model MP-80), align the spherical joint with the polishing disc, set the rotation speed to 1200 rpm (reduce the rotation speed to prevent the small joints from cracking), and polish for 6 minutes. After polishing, use anhydrous ethanol (analytical pure) to ultrasonically clean for 4 minutes (frequency 40 kHz) to remove residual polishing paste, and then place it in a 60°C vacuum drying oven for 10 minutes.

[0126] Step S5, application of wear-resistant coating

[0127] Nano-diamond coating is prepared by chemical vapor deposition (CVD) method, and the deposition parameters are adjusted according to the small substrate. The specific operation is as follows:

[0128] 1. Put the treated substrate into a cold-wall CVD reaction chamber, seal it, and then pump it to 3x10^-4 Pa by a molecular pump to ensure that the reaction chamber is free from impurity gas interference;

[0129] 2. Heat the reaction chamber to 850°C (lower than Example 1 to avoid overheating and deformation of the small nickel-titanium alloy substrate), and introduce a mixture of methane and hydrogen gas (flow ratio 1:10), with methane flow rate 8 sccm and hydrogen flow rate 80 sccm, and maintain the reaction chamber pressure at 3 kPa;

[0130] 3. Maintain the deposition time for 2.5 hours, and monitor the coating thickness in real time by an in-situ optical monitoring system to ensure that the final coating thickness is uniformly controlled at 6 microns (to avoid the coating being too thick, causing the drill bit diameter to exceed the adaptation range of small blood vessels);

[0131] 4. After deposition is completed, turn off the heating device, continue to introduce hydrogen gas until the reaction chamber temperature drops below 180°C, and then slowly take out the drill bit substrate to prevent the coating from cracking due to sudden temperature change.

[0132] Step S6, heat treatment

[0133] Vacuum heat treatment: Put the drill bit substrate coated with the coating into a small vacuum heat treatment furnace (model ZT-30), pump it to 1x10^-3 Pa by a diffusion pump, heat it to 510°C at a rate of 5°C / min, and keep it at this temperature for 35 minutes (adapt to the small substrate, shorten the holding time to avoid grain coarsening); then introduce nitrogen gas with a purity of 99.999% as a cooling medium, control the cooling rate to be 55°C / min, and cool the furnace temperature to room temperature (25°C) to ensure that the nickel-titanium alloy remains super-elastic.

[0134] Aging treatment: After the cooled drill bit substrate is transferred to a precision box resistance furnace, it is kept at 400°C for 10 minutes (consistent with the previous two examples to ensure performance stability), and then cooled to room temperature at a rate of 10°C / min to further stabilize the coating and substrate bonding force, avoiding the fracture of small substrates due to stress concentration.

[0135] Step S7, final assembly

[0136] Drive shaft preparation: Select multiple strands of 316L medical stainless steel wire (single wire diameter 0.06mm, meet the driving needs of small blood vessels) and weave into a flexible drive shaft, weaving density 75% (balance flexibility and torque transmission efficiency), shaft diameter 0.9mm; coat the outer surface of the drive shaft with a polytetrafluoroethylene (PTFE) coating, coating thickness 0.1mm (thinner than the previous two examples to reduce intravascular space occupation), sintered at 370°C for 30 minutes to ensure firm coating adhesion.

[0137] Laser welding: Use a pulse laser welding machine model HGL-20 to butt joint the drill bit substrate and the drive shaft (butt joint gap ≤0.01mm to avoid welding misplacement of small structures), set the welding parameters: power 23W, pulse time 0.25 seconds, focus diameter 0.1mm, and use a microscopic camera to monitor the weld state in real time during the welding process. After welding, use a 100x metallographic microscope to observe the weld to ensure that there are no cracks, pores or other defects.

[0138] Strength detection: Use a miniature tensile testing machine (model HT-100) to test the tensile strength of the connection part, test force 30N (adapted to the stress requirements of small structures), hold for 10 seconds, the connection is not loose and the weld does not crack, the connection strength meets the clinical use standard.

[0139] Step S8, cleaning and packaging

[0140] Ultrasonic cleaning: Place the assembled drill bit into a small ultrasonic cleaner (model KQ-300), add a mixture of deionized water and anhydrous ethanol (volume ratio 1:1, both analytical pure), set the cleaning frequency to 40kHz and the cleaning time to 10 minutes; after cleaning, rinse with ultrapure water (resistivity ≥18.2MΩ·cm) for 3 times, 1.5 minutes each time, then dry in a 75°C vacuum drying oven (vacuum degree 5x10^-2Pa) for 25 minutes to ensure that the drill bit surface is free of residual cleaning agent.

[0141] Sterile packaging: Place the dried drill bit into an ethylene oxide sterilization cabinet (model EO-100), set the sterilization parameters: temperature 35°C (to avoid high temperature affecting the stability of small coatings), ethylene oxide concentration 650mg / L, relative humidity 55%, sterilization time 4.5 hours; after sterilization, store in a 30°C, ventilation volume 4m 3The sample was aerated and aerated in a chamber for 24 hours. Gas chromatography was used to ensure that the residual ethylene oxide content was ≤8 μg / g (lower than the previous two examples, suitable for the higher safety requirements of small blood vessels). Finally, in a Class 100 sterile cleanroom, the drill bit was placed in a miniature medical-grade Tyvek bag (model TY-1055A, size 3cm × 8cm), heat-sealed (heat-sealing temperature 180℃, pressure 0.3MPa), and labeled with the product model (FM-10-06), production batch number (20240615), production date (June 15, 2024), and sterilization date (June 16, 2024).

[0142] Performance verification:

[0143] The rotary drill bit prepared in this embodiment can pass smoothly through a simulated distal small tortuous blood vessel model of an LCX (bending angle 88°, radius of curvature 3.5mm, blood vessel inner diameter 2.0mm), with a maximum resistance ≤5N. Grinding tests were conducted on calcified plaque simulation material (hardness HV480, thickness 0.5mm) at a speed of 170,000 rpm, achieving a grinding efficiency of 0.35mm. 3 / min, and the coating did not peel off (the coating integrity was ≥99% as observed by scanning electron microscopy); in vitro testing of porcine coronary artery specimens showed that the postoperative endothelial damage rate of the vessel wall was ≤5%, with no complications such as vascular perforation or dissection, meeting the clinical treatment needs of small and tortuous vascular lesions.

[0144] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0145] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flexible, bendable rotary drilling bit for endocoronary plaque removal, characterized in that, It includes a drill bit body, a wear-resistant coating covering the surface of the drill bit body, and a flexible drive shaft connected to one end of the drill bit body; The drill bit body is made of nickel-titanium alloy wire. The composition of the nickel-titanium alloy is: 55%-56% nickel and the balance titanium. In addition, 0.5%-1.0% chromium and 0.1%-0.3% iron are added to the nickel-titanium alloy. The diameter of the nickel-titanium alloy wire is 0.5mm-1.0mm. The drill bit body has a multi-segment structure, with each segment having a length of 0.5mm-1.0mm and a total length of 10mm-20mm. Adjacent segments are detachably connected by a micro-spherical joint with a diameter of 0.3mm-0.5mm, allowing the drill bit body to bend up to 90 degrees in multiple directions. The outer surface of the drill bit base is provided with a spiral groove, the depth of which is 0.05mm-0.1mm, the width of which is 0.1mm-0.2mm, and the spacing between adjacent grooves is 0.2mm-0.3mm. The wear-resistant coating fills the spiral groove and covers the outer surface of the drill bit substrate. The raw material of the wear-resistant coating is nano-diamond powder or silicon carbide powder. The purity of the nanodiamond powder is ≥99.9%, the purity of the silicon carbide powder is ≥99.5%, and the particle size range of the nanodiamond powder or silicon carbide powder is 0.1μm-10μm, and the thickness of the wear-resistant coating is 5μm-10μm. The drill bit base is hemispherical at one end away from the flexible drive shaft, and the diameter of the hemispherical shape is the same as the diameter of the drill bit base. The flexible drive shaft is woven from multiple strands of stainless steel wire with a diameter of 0.05mm-0.1mm. The flexible drive shaft is covered with a polytetrafluoroethylene coating with a thickness of 0.1mm-0.2mm. The diameter of the flexible drive shaft is 0.8mm-1.5mm.

2. The flexible, bendable rotary drilling bit for coronary artery plaque removal according to claim 1, characterized in that, Before processing, the nickel-titanium alloy wire is ultrasonically cleaned with acetone and deionized water for 10 minutes in sequence to remove oxides and impurities from the surface.

3. The flexible, bendable rotary drilling bit for endocoronary plaque removal according to claim 1, characterized in that, The outer surface of the miniature ball joint is mechanically polished using diamond polishing paste with a particle size of 0.5μm-1.0μm. The polishing is performed on a miniature polishing machine at a speed of 1000rpm-2000rpm for 5min-10min. After polishing, the surface is cleaned with ethanol to remove any residual polishing paste.

4. The flexible, bendable rotary drilling bit for endocoronary plaque removal according to claim 1, characterized in that, The drill bit base and the flexible drive shaft are fixed by laser welding. The parameters of the laser welding are: power 20W-30W, pulse time 0.1s-0.5s, and focal diameter 0.1mm.

5. A method for processing intraluminal coronary plaques using a flexible, bendable rotary drilling bit as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Material preparation: Select nickel-titanium alloy wire with the composition and diameter described in claim 1 as the raw material for the drill bit matrix. Ultrasonically clean the nickel-titanium alloy wire with acetone for 10 minutes, and then ultrasonically clean it with deionized water for 10 minutes to remove surface oxides and impurities. Select nano-diamond powder or silicon carbide powder with the purity and particle size described in claim 1 as the raw material for the wear-resistant coating. Store the wear-resistant coating raw material in a dry environment with a relative humidity of ≤30%. S2. Drill bit structure design: Design the multi-segment drill bit base structure, spiral groove structure and hemispherical tip structure as described in claim 1, and design a micro spherical joint structure that is adapted to the drill bit base. S3. Substrate Forming: The nickel-titanium alloy wire cleaned in step S1 is cut using a fiber laser to form a multi-segment drill bit substrate. The laser cutting parameters are set as follows: power 50W-100W, cutting speed 10mm / s-20mm / s, frequency 1kHz-5kHz, and spot diameter 0.01mm-0.02mm. Argon gas with a flow rate of 5L / min-10L / min is introduced as a protective gas during the cutting process. After cutting, the drill bit substrate is electrochemically polished: a mixture of phosphoric acid and sulfuric acid with a volume ratio of 3:1 is used as the polishing liquid. The polishing voltage is set to 5V-10V and the polishing time is 30s-60s. After polishing, the substrate is rinsed with deionized water and dried at 60℃-80℃. S4. Manufacturing of the ball joint: At both ends of each drill bit base formed in step S3, a micro-forging machine is used to form a micro-ball joint. The micro-forging parameters are set as follows: stamping pressure 0.5MPa-1.0MPa, temperature 200℃-300℃, holding time 10s-20s. The mold used for micro-forging is made of tungsten carbide. The outer surface of the micro-ball joint is mechanically polished: diamond polishing paste with a particle size of 0.5μm-1.0μm is used, and polishing is performed on a micro-polishing machine at a speed of 1000rpm-2000rpm for 5min-10min. After polishing, the surface is rinsed with ethanol to remove residual polishing paste. S5. Application of wear-resistant coating: When nano-diamond powder is used as the raw material for wear-resistant coating, the wear-resistant coating is prepared by chemical vapor deposition: The drill bit substrate after step S4 is placed in a chemical vapor deposition reaction chamber, heated to 800℃-1000℃, the pressure in the reaction chamber is maintained at 1kPa-10kPa, a mixed gas with a volume ratio of methane to hydrogen of 1:10 is introduced, and deposition is carried out for 2h-4h to make the thickness of the wear-resistant coating reach 5μm-10μm; When silicon carbide powder is selected as the raw material for wear-resistant coating, the wear-resistant coating is prepared by physical vapor deposition: the deposition temperature is set to 400℃-600℃, the deposition pressure is 0.1Pa-1Pa, the sputtering power is 500W-1000W, the deposition time is 1h-2h, and after deposition, the coating surface is lightly polished for 2min-3min with diamond polishing paste with a particle size of 0.5μm-1.0μm to remove protruding particles; S6. Heat Treatment: Vacuum heat treatment is performed on the drill bit substrate after applying the wear-resistant coating in step S5: The drill bit substrate is placed in a vacuum furnace, the vacuum degree of the vacuum furnace is ≤10^-3Pa, heated to 500℃-550℃ and held for 30min-60min; then nitrogen is introduced as a cooling medium and rapidly cooled to room temperature at a cooling rate of ≥50℃ / min; after cooling, the drill bit substrate is subjected to aging treatment: held at 400℃ for 10 minutes, and then allowed to cool naturally to room temperature. S7. Final Assembly: Select the flexible drive shaft with the structure described in claim 1, and use a laser welding machine to connect the drill bit substrate processed in step S6 to the flexible drive shaft; the laser welding parameters are: power 20W-30W, pulse time 0.1s-0.5s, focal diameter 0.1mm; after welding, use a tensile testing machine to test the connection strength to ensure that there is no looseness at the connection; S8. Cleaning and Packaging: Place the rotary drill bit assembled in step S7 into an ultrasonic cleaner, using a 1:1 volume ratio of deionized water and ethanol as the cleaning solution. Set the cleaning frequency to 40kHz and the cleaning time to 10 minutes. After cleaning, rinse three times with purified water and then dry at 60℃-80℃. Sterilize the dried rotary drill bit with ethylene oxide. After sterilization, package it in a Class 100 sterile environment using medical-grade Tyvek bags, and label the packaging with the drill bit model, specifications, production batch number, production date, and sterilization date.

6. A method for processing intraluminal plaques in coronary arteries using a flexible, bendable rotary drilling bit according to claim 5, characterized in that, The argon gas mentioned in step S3 has a purity of ≥99.99%.

7. A method for processing intraluminal plaques in coronary arteries using a flexible, bendable rotary drilling bit according to claim 1, characterized in that, When preparing the silicon carbide wear-resistant coating using physical vapor deposition in step S5, the sputtering target is a silicon carbide target with a purity of ≥99.9%.

8. A method for processing intraluminal plaques in coronary arteries using a flexible, bendable rotary drilling bit according to claim 1, characterized in that, The parameters for ethylene oxide sterilization in step S8 are: sterilization temperature 30℃-50℃, ethylene oxide concentration 600mg / L-800mg / L, sterilization time 4h-6h, and ventilation and desorption for 24 hours after sterilization.

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