Medical nickel-titanium alloy serpentine tube and preparation method thereof
By using a zoned, differentiated opening design and gradient heat treatment of nickel-titanium alloy snake-bone tubes, the problem of mismatch between flexibility and stiffness in human body cavities has been solved, achieving intelligent distribution of flexibility and stiffness, and improving the operational performance and reliability of interventional devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI YIFANTAI TECH
- Filing Date
- 2026-04-24
- Publication Date
- 2026-07-10
AI Technical Summary
The existing nickel-titanium alloy snake bone tube has a mismatch between flexibility and stiffness distribution in human body cavities, resulting in problems such as high resistance during interventional procedures, easy tissue damage, short service life, and insufficient biocompatibility.
By adopting a zoned differentiated opening design, combined with spiral staggered arrangement and gradient heat treatment, nickel-titanium alloy snake bone tubes with large bending flexible sections and straight support sections are prepared. By using large-sized dense elongated oval holes at sharp bends and small-sized sparse circular holes at straight sections, intelligent distribution of flexibility and stiffness is achieved, and surface quality is improved by high-precision laser cutting and gradient polishing.
It significantly reduces resistance to interventional procedures, improves fatigue resistance and service life, ensures unobstructed access, enhances biocompatibility, adapts to the flexibility and deformation recovery ability of complex cavities, and improves the safety and efficiency of surgical procedures.
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This application relates to the field of medical devices, and more specifically, to a medical nickel-titanium alloy snake-bone tube and its preparation method. Background Technology
[0002] In the field of interventional medical devices, instruments such as endoscopic insertion tubes, interventional catheter guiding sheaths, and biopsy channels are important tools for modern medical diagnosis and treatment, and their performance directly affects the success rate of surgery and patient safety. The core components of these instruments often need to have excellent flexibility, support, and good biocompatibility in order to provide precise navigation, stable support, or efficient operating channels in complex cavities of the human body (such as the digestive tract, blood vessels, and respiratory tract).
[0003] To achieve flexible guidance of instruments within human cavities, a flexible nickel-titanium alloy serpentine tube with multiple rows of perforations in its wall is often used. Currently, the design typically employs circular or single-shaped perforations of equal diameter and spacing, evenly distributed along the tube in a straight line or simple spiral. The manufacturing process usually involves laser-cutting the straight tubular nickel-titanium alloy material to create the perforations, followed by bending and heat treatment for shaping. This design primarily reduces the tube's stiffness through the perforations, thereby achieving basic flexibility to meet the requirements for bending and navigation within cavities.
[0004] However, the above-mentioned uniform aperture design has significant technical defects, specifically in the following aspects: 1) Macroscopic performance mismatch: Incompatibility between overall flexibility and cavity morphology: Human cavities (such as the digestive tract and blood vessels) have complex anatomical shapes with varying curvatures. The existing snake-bone tube's "uniform size and equidistant distribution" opening design results in a constant overall stiffness. This "unchanging" mechanical characteristic cannot meet the actual clinical needs of "more flexibility in sharp bends and stronger strength in straight sections." The consequence is that excessive resistance and easy tissue damage occur when passing through sharp bends; while in straight sections, insufficient support may cause collapse and blockage of the instrument channel. 2) Microstructural Risks: The layout of the openings leads to stress concentration and early fatigue: Regularly arranged openings create continuous weak points on specific cross-sections of the tube. When the serpentine tube is repeatedly bent, stress continuously concentrates at the edges of these fixed openings, making it highly susceptible to fatigue microcracks. This structural defect directly limits the lifespan and reliability of the device, making it unsuitable for high-standard applications requiring multiple operations or long-term implantation. 3) Inefficient manufacturing processes lead to unstable and insufficient superelastic properties: On the one hand, the uniform open-pore structure cannot actively regulate and match the deformation and springback behavior of the nickel-titanium alloy in different sections; on the other hand, the lack of precise heat treatment processes that match the alloy composition (especially the content of added elements) prevents the material's excellent superelasticity (shape memory effect) from being stably and fully activated and solidified. This results in significant batch-to-batch variations in the mechanical properties of the snake-bone tube, and under actual body temperature conditions, it cannot consistently guarantee optimal flexibility and deformation recovery. 4) Clinical operation safety needs to be improved: The existing snake bone tube opening edge is not smooth enough, which is easy to scratch the cavity mucosa; the surface biocompatibility treatment process of some products is rough, resulting in a high risk of postoperative infection; and there is a lack of customized rigidity design for different cavity anatomical features, making it difficult for general-purpose products to adapt to the needs of multi-site intervention.
[0005] Therefore, there is a need for a snake-bone tube that is more flexible in sharp bends, stronger in straight sections, better matched to human cavities, and more reliable. Summary of the Invention
[0006] In order to provide a more flexible snake-bone tube with a stronger straight section, which is more compatible with human body cavities and more reliable, this application provides a medical nickel-titanium alloy snake-bone tube and its preparation method.
[0007] In the first aspect, this application provides a medical nickel-titanium alloy snake bone tube, which adopts the following technical solution: A medical nickel-titanium alloy snake-bone tube includes a snake-bone tube body, which comprises a highly flexible, curved section, a transition balance section, and a straight support section distributed along the axial direction. The radius of curvature of the highly flexible, curved section is ≤15mm. The snake-bone tube body has spiral openings, with the openings at the highly flexible, curved section being elongated oval holes and the openings at the straight support section being circular holes. The hole size and density of the highly flexible, curved section are both greater than those of the straight support section, and the hole size and density of the transition balance section are between those of the highly flexible, curved section and the straight support section. The openings on the snake bone tube body are arranged in a spiral staggered pattern, and the center lines of adjacent holes are circumferentially offset by 60°-120°.
[0008] By adopting the above technical solution, the snake-bone tube in this application features a zoned and differentiated opening design along the axial direction. In the large-bending flexible section with a small radius of curvature, large and densely distributed elongated oval openings are used to maximize the flexibility in this area, allowing it to easily pass through sharp bends without damaging tissue. In the straight support section, in the near-direct area, small and sparsely distributed circular openings are used to strengthen radial support and ensure sufficient stiffness in the straight section to maintain the unobstructed access of the instrument channel. The transition balance section is located in the area between the two, with opening parameters between the large-bending flexible section and the straight support section, achieving a smooth transition between flexibility and stiffness.
[0009] In this application, the snake-bone tube utilizes a zoned perforation design to achieve an intelligent stiffness distribution along the axial direction, exhibiting flexibility at sharp bends and rigidity at straight sections. This fundamentally resolves the inherent imbalance between flexibility and support in traditional structures, allowing it to smoothly conform to complex cavities, significantly reducing interventional resistance while ensuring unobstructed flow throughout the entire channel. Furthermore, the perforations on the snake-bone tube in this application are arranged in a spiral staggered pattern, effectively dispersing stress concentration and preventing the formation of continuous weak mechanical zones, thereby improving the overall structure's fatigue resistance and reliability.
[0010] Optionally, the snake bone tube body comprises the following chemical components by weight percentage: 52-57% nickel, 0.2-2.8% vanadium, and the balance of titanium and unavoidable trace elements.
[0011] Secondly, this application provides a method for preparing a medical nickel-titanium alloy snake bone tube, using the following technical solution: A method for preparing a medical nickel-titanium alloy snake-bone tube includes the following steps: S1. Solution treatment is performed on the nickel-titanium serpentine tube matrix. S2. The solution-treated snake bone tube matrix is laser-cut to obtain a snake bone tube body with the hole distribution as described. During laser cutting, an auxiliary gas is introduced and the pressure is maintained at 0.5-0.8 MPa. S3. The snake bone tube body after the hole is opened in step S2 is cold-bent and heat-treated to set its shape. S4. The snake bone tube body processed in step S3 is placed in a magnetic polishing machine for physical polishing, then immersed in a chemical polishing solution for chemical polishing, washed with water and dried to obtain a medical nickel-titanium alloy snake bone tube.
[0012] By adopting the above technical solution, the snake bone tube matrix is first subjected to solution treatment to eliminate the internal stress that may exist in its factory state, and to homogenize the microstructure, laying the foundation for subsequent processing. Then, a high-precision fiber laser cutting system is used to laser cut holes according to the dense elongated holes in the large bending flexible section and the sparse circular holes in the straight support section. During the cutting, gas is introduced to control the pressure. Under this pressure, the high-speed airflow can effectively blow away the molten metal slag generated during cutting, ensuring the cut seam is clean and preventing secondary adhesion. At the same time, the forced cooling effect of the airflow on the cutting area significantly reduces the local heat accumulation and overheating of the nickel-titanium alloy caused by continuous laser irradiation, thereby minimizing the heat-affected zone and ensuring high geometric accuracy, no oxidation, and minimal loss of microstructure at the edge of the hole.
[0013] Following cold bending and heat treatment, a gradient composite polishing process is performed, including sequential physical and chemical polishing. Physical polishing quickly removes macroscopic surface imperfections and provides targeted finishing of critical areas such as opening edges. Chemical polishing further removes the oxide layer, microcracks, and microscopic unevenness remaining from physical polishing, resulting in a uniform high-gloss finish across the entire surface of the snake-bone tube, both inside and out. This treatment not only improves the biocompatibility of the snake-bone tube but also reduces frictional resistance during its movement within the cavity, facilitating smoother passage through sharp bends and support in straight sections.
[0014] Optionally, the solution treatment parameters in step S1 are: heat treatment at 850-900℃ for 30-40 minutes followed by water cooling.
[0015] Optionally, when cutting large-sized elongated holes at the flexible section with large bends in step S2, a power of 140-150W and a speed of 50-70mm / s may be used. When cutting small-sized round holes at the straight support section, the power is 120-130W and the speed is 80-100mm / s.
[0016] Optionally, the specific operation of cold bending in step S3 is as follows: the snake tube body processed in step S2 is installed on the shaping mold, the cold bending process is used to obtain the snake-shaped curved profile, and then it is kept at 300-350℃ for 10-20 minutes and then cooled in the furnace.
[0017] By adopting the above technical solution, the bending shape is initially stabilized after a short period of heat preservation following cold bending.
[0018] Optionally, the heat treatment and shaping operation in step S3 is as follows: When the vanadium content is 0.2-1.0wt%, keep warm at 510-520℃ for 10-20 minutes; When the vanadium content is 1.0-2.8wt%, keep warm at 480-500℃ for 25-40 minutes.
[0019] By adopting the above technical solution, this application dynamically adjusts the heat treatment temperature and time based on the vanadium content in the serpentine tube. Vanadium, as an alloying element, can effectively control the phase transformation temperature of nickel-titanium alloys. As the vanadium content increases, the phase transformation temperature tends to decrease. Therefore, in order to achieve the phase transformation temperature control below the target body temperature, it is necessary to adjust the heat treatment temperature and time in reverse according to the vanadium content to compensate for the influence of vanadium on the phase transformation temperature. For low vanadium content, a higher qualitative temperature range is selected for heat preservation, while a slightly lower temperature range is used for higher vanadium content. The heat preservation time is extended accordingly with the increase of vanadium content. This dynamic adjustment enables the austenitic phase transformation end temperature of the serpentine tube to be precisely set slightly below the human body temperature range, thereby ensuring that it is flexible and easily shaped at room temperature, and instantly transforms into a strong, highly elastic superelastic state after entering the human body, and permanently "memorizes" its preset bending shape.
[0020] Optionally, the chemical polishing solution in step S4 includes 15-30% hydrofluoric acid, 15-30% nitric acid, and the balance water. Furthermore, chemical polishing involves immersion treatment at room temperature for 50-280 seconds.
[0021] By adopting the above technical solution, hydrofluoric acid dissolves the oxide layer on the surface of nickel-titanium alloy, while nitric acid removes micro-unevenness and micro-cracks through oxidation.
[0022] Optionally, during heat treatment and shaping in step S3, an axial gradient magnetic field is applied to the snake-bone tube body, with the magnetic field strength at the large bending flexible section being 0.4-0.6T and the magnetic field strength at the straight support section being 0.1-0.2T.
[0023] By adopting the above technical solution, the magnetic field induces the large bending segment to preferentially form a flexible martensite variant during phase transformation, while the straight segment retains the highly elastic austenite phase, thereby achieving the "self-softening of sharp bends and self-strengthening of straight segments" response at body temperature.
[0024] In summary, this application has the following beneficial effects: 1. In this application, the snake-bone tube features a zoned and differentiated opening design along the axial direction. In the flexible section with a small radius of curvature, large and densely distributed elongated oval openings are used to maximize the flexibility in this area, allowing it to easily pass through sharp bends without damaging the tissue. In the straight support section, which is near the direct area, small and sparsely distributed circular openings are used to strengthen the radial support and ensure sufficient stiffness in the straight section to maintain the unobstructed access of the instrument channel. The transition balance section is located in the area between the two, with opening parameters between the flexible section with large curvature and the straight support section, achieving a smooth transition between flexibility and stiffness. 2. In this application, the snake bone tube is designed with partitioned openings, which enables the snake bone tube to achieve an intelligent stiffness distribution in the axial direction of "flexible at sharp bends and rigid at straight sections". This fundamentally solves the contradiction of the imbalance between flexibility and support in traditional structures, allowing it to smoothly fit into complex cavities, significantly reducing the resistance of interventional operations, while ensuring unobstructed passage throughout the entire channel. 3. In this application, the openings on the snake bone tube are arranged in a spiral staggered manner, which effectively disperses stress concentration and avoids the formation of continuous weak mechanical zones, thereby improving the fatigue resistance and reliability of the overall structure. Combined with the high-pressure air laser cutting process, stress is effectively dispersed and the integrity of the opening edges is ensured. With the heat treatment process, the generation of fatigue cracks is suppressed, resulting in a significant improvement in the fatigue resistance and service life of the product. 4. In this application, laser cutting parameters and high-pressure air assistance, combined with a dynamic heat treatment process based on vanadium content, are used to ensure that the snake bone tube has high dimensional accuracy and surface quality, and exhibits excellent and stable superelastic recovery performance, thereby achieving high production consistency and pass rate. 5. In this application, cold bending forming, combined with the above-mentioned performance improvements, makes the instrument more passable during surgery, more accurate in operation feedback, improves safety and efficiency, and also broadens its application potential in interventional surgeries with higher requirements. Detailed Implementation
[0025] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources. Example 1
[0026] A method for preparing a medical nickel-titanium alloy snake-bone tube includes the following steps: S1. Select seamless nickel-titanium alloy tubing with a chemical composition of 54.5wt% nickel, 1.2wt% vanadium, and the balance being titanium and unavoidable trace elements as the nickel-titanium serpentine tube matrix. The initial specifications of the tubing are an outer diameter of 3.0mm and a wall thickness of 0.4mm. The snake bone tube matrix is first subjected to solution treatment, specifically by holding at 880℃ for 35 minutes and then water cooling, in order to eliminate the internal stress that may exist in its factory state and to homogenize the microstructure. S2. A high-precision fiber laser cutting machine is used to perform laser cutting and hole opening operations under the assistance of dry compressed air at 0.6MPa. The specific operation is as follows: First, the snake bone tube base is cut into 100mm sections. Then, spiral holes with a zoned design are processed on the tube body. The tube body is divided into a large bending flexible section, a transition balance section, and a straight support section. The straight support section is 58mm long, the transition balance section is 4mm long, and the large bending flexible section is 38mm long. Circular holes with a diameter of 0.8mm are cut on the straight support section, with a hole density of 1.5 holes / cm. Oblong holes with a long diameter of 1.8mm and a short diameter of 0.8mm are cut on the large bending flexible section, with a hole density of 3.0 holes / cm. Circular holes with a diameter of 0.9mm are cut on the transition balance section, with a hole density of 2 holes / cm. All the above holes are arranged in a spiral staggered pattern on the circumference of the tube body, with the center lines of adjacent holes offset by 90° circumferentially. When cutting large-sized elongated holes at the flexible section of the large bend, a power of 145W and a speed of 60mm / s are used; when cutting small-sized circular holes at the straight support section, a power of 125W and a speed of 90mm / s are used; when cutting circular holes at the transition balance section, a power of 130W and a speed of 80mm / s are used. S3. Place the straight snake-bone tube body after the hole is opened in a special mold and cold bend it into a preset arc shape. The radius of curvature of the large bending flexible section is ≤15mm. After holding it at 320℃ for 15min, it is cooled with the furnace. Then, the tube section fixed in the mold is placed in a hot heating furnace and heated to 495℃ in an air atmosphere. It is held for 28min and then water quenched to achieve heat treatment. S4. Place the heat-treated snake tube body from step S3 into a magnetic polishing machine for 25 minutes to remove surface defects. Then, use a robotic arm to hold a flexible polishing head and perform targeted polishing on all opening edges for 3 minutes to complete physical polishing. Then, the physically polished snake bone tube body is immersed in a chemical polishing solution at a temperature of 25°C for 70 seconds, then rinsed with high-pressure deionized water and dried to obtain a medical nickel-titanium alloy snake bone tube. The chemical polishing solution is prepared by mixing 20% hydrofluoric acid, 20% nitric acid, and the remainder water. Example 2
[0027] A method for preparing a medical nickel-titanium alloy snake-bone tube includes the following steps: S1. Select seamless nickel-titanium alloy tubing with a chemical composition of 52wt% nickel, 0.2wt% vanadium, and the balance being titanium and unavoidable trace elements as the nickel-titanium serpentine tube matrix. The initial specifications of the tubing are an outer diameter of 3.0mm and a wall thickness of 0.4mm. The snake bone tube matrix is first subjected to solution treatment, specifically by holding at 850℃ for 40 minutes and then water cooling, in order to eliminate the internal stress that may exist in its factory state and to homogenize the microstructure. S2. A high-precision fiber laser cutting machine is used to perform laser cutting and hole opening operations under the assistance of dry compressed air at 0.5MPa. The specific operation is as follows: First, the snake bone tube base is cut into 100mm sections. Then, spiral holes with a zoned design are processed on the tube body. The tube body is divided into a large bending flexible section, a transition balance section, and a straight support section. The straight support section is 58mm long, the transition balance section is 4mm long, and the large bending flexible section is 38mm long. Circular holes with a diameter of 0.8mm are cut on the straight support section, with a hole density of 1.5 holes / cm. Oblong holes with a long diameter of 1.8mm and a short diameter of 0.8mm are cut on the large bending flexible section, with a hole density of 3.0 holes / cm. Circular holes with a diameter of 0.9mm are cut on the transition balance section, with a hole density of 2 holes / cm. All the above holes are arranged in a spiral staggered pattern on the circumference of the tube body, with the center lines of adjacent holes offset by 90° circumferentially. When cutting large-sized elongated holes at the flexible section of the large bend, a power of 140W and a speed of 50mm / s are used; when cutting small-sized circular holes at the straight support section, a power of 120W and a speed of 80mm / s are used; when cutting circular holes at the transition balance section, a power of 130W and a speed of 70mm / s are used. S3. Place the straight snake-bone tube body after the hole is opened in a special mold and cold bend it into a preset arc shape. The radius of curvature of the large bending flexible section is ≤15mm. After holding it at 300℃ for 20min, it is cooled with the furnace. Then, the tube section fixed in the mold is placed in a hot heating furnace and heated to 515℃ in an air atmosphere. It is held for 15min and then water quenched to achieve heat treatment. S4. Place the heat-treated snake tube body from step S3 into a magnetic polishing machine for 25 minutes to remove surface defects. Then, use a robotic arm to hold a flexible polishing head and perform targeted polishing on all opening edges for 3 minutes to complete physical polishing. Then, the physically polished snake bone tube body is immersed in a chemical polishing solution at a temperature of 25°C for 280 seconds, and then rinsed with high-pressure deionized water and dried to obtain a medical nickel-titanium alloy snake bone tube. The chemical polishing solution is prepared by mixing 15% hydrofluoric acid, 15% nitric acid, and the remainder water. Example 3
[0028] A method for preparing a medical nickel-titanium alloy snake-bone tube includes the following steps: S1. A seamless nickel-titanium alloy tube with a chemical composition of 57wt% nickel, 2.8wt% vanadium, and the balance being titanium and unavoidable trace elements is selected as the nickel-titanium serpentine tube matrix. The initial specifications of the tube are an outer diameter of 3.0mm and a wall thickness of 0.4mm. The snake bone tube matrix is first subjected to solution treatment, specifically by holding at 900℃ for 30 minutes and then water cooling, in order to eliminate the internal stress that may exist in its factory state and to homogenize the microstructure. S2. A high-precision fiber laser cutting machine is used to perform laser cutting and hole opening operations under the assistance of dry compressed air at 0.8MPa. The specific operation is as follows: First, the snake bone tube base is cut into 100mm sections. Then, spiral holes with a zoned design are processed on the tube body. The tube body is divided into a large bending flexible section, a transition balance section, and a straight support section. The straight support section is 58mm long, the transition balance section is 4mm long, and the large bending flexible section is 38mm long. Circular holes with a diameter of 0.8mm are cut on the straight support section, with a hole density of 1.5 holes / cm. Oblong holes with a long diameter of 1.8mm and a short diameter of 0.8mm are cut on the large bending flexible section, with a hole density of 3.0 holes / cm. Circular holes with a diameter of 0.9mm are cut on the transition balance section, with a hole density of 2 holes / cm. All the above holes are arranged in a spiral staggered pattern on the circumference of the tube body, with the center lines of adjacent holes offset by 90° circumferentially. When cutting large-sized elongated holes at the flexible section of the large bend, a power of 150W and a speed of 70mm / s are used; when cutting small-sized circular holes at the straight support section, a power of 130W and a speed of 100mm / s are used; when cutting circular holes at the transition balance section, a power of 140W and a speed of 80mm / s are used. S3. Place the straight snake-bone tube body after the hole is opened in a special mold, and cold bend it into a preset arc shape. The radius of curvature of the large bending flexible section is ≤15mm. After holding it at 350℃ for 10min, it is cooled with the furnace. Then, the tube section fixed in the mold is placed in a hot heating furnace, heated to 480℃ in an air atmosphere, held for 40min, and then water quenched to achieve heat treatment. S4. Place the heat-treated snake tube body from step S3 into a magnetic polishing machine for 25 minutes to remove surface defects. Then, use a robotic arm to hold a flexible polishing head and perform targeted polishing on all opening edges for 3 minutes to complete physical polishing. Then, the physically polished snake bone tube body is immersed in a chemical polishing solution at a temperature of 25°C for 50 seconds, then rinsed with high-pressure deionized water and dried to obtain a medical nickel-titanium alloy snake bone tube. The chemical polishing solution is prepared by mixing 30% hydrofluoric acid, 30% nitric acid, and the remainder water. Example 4
[0029] A method for preparing a medical nickel-titanium alloy snake-bone tube is carried out according to the method in Example 1, except that step S3 is specifically performed as follows: The straight snake-bone tube body after the hole is opened is placed in a special mold and cold-bent into a preset arc shape. The radius of curvature of the large bending flexible section is ≤15mm. After holding at 320℃ for 15min, it is cooled with the furnace. Then the tube section fixed in the mold is placed in a hot heating furnace, heated to 510℃ in an air atmosphere, held for 28min, and then water quenched to achieve heat treatment. Example 5
[0030] A method for preparing a medical nickel-titanium alloy snake-bone tube is carried out according to the method in Example 1, except that in step S3, while the tube segment fixed in the mold is placed in a heating furnace for heat treatment, an axial gradient magnetic field is also applied to the snake-bone tube body. The magnetic field strength at the large bending flexible section is 0.5T, and the magnetic field strength at the straight support section is 0.1T. Example 6
[0031] A method for preparing a medical nickel-titanium alloy snake-bone tube is carried out according to the method in Example 1, except that in step S3, while the tube segment fixed in the mold is placed in a heating furnace for heat treatment, an axial gradient magnetic field is also applied to the snake-bone tube body. The magnetic field strength at the large bending flexible section is 0.4T, and the magnetic field strength at the straight support section is 0.1T. Example 7
[0032] A method for preparing a medical nickel-titanium alloy snake-bone tube is carried out according to the method in Example 1, except that in step S3, while the tube segment fixed in the mold is placed in a heating furnace for heat treatment, an axial gradient magnetic field is also applied to the snake-bone tube body. The magnetic field strength at the large bending flexible section is 0.6T, and the magnetic field strength at the straight support section is 0.2T.
[0033] Comparative Example 1 A method for preparing a medical nickel-titanium alloy snake bone tube is carried out according to the method in Example 1, except that the openings on the tube body in step S2 are not spirally arranged, but are arranged in a specific pattern.
[0034] Comparative Example 2 A method for preparing a medical nickel-titanium alloy snake bone tube is carried out according to the method in Example 1, except that in step S2, the openings on the tube segment are all circular and evenly distributed, and the radius of the circular holes is 0.8 mm, the opening density is 2 holes / cm, and they are evenly distributed along the entire tube segment.
[0035] Performance testing The radial pressure bearing capacity of the straight support section and the passability of the large bending flexible section of the snake tube prepared in the above embodiments and comparative examples were tested. Specifically, the radial pressure was gradually increased on the straight support section of the prepared snake tube until the sample collapsed, and the radial pressure data were statistically analyzed. In addition, a simulated cavity system with sharp bends of different curvature radii was constructed. Then, the flexible end of the fabricated snake-bone tube with large curvature was pushed into the simulated cavity system until the flexible end with large curvature completely passed through the sharp bend. The curvature radius of the simulated cavity was recorded when the snake-bone tube could pass through the sharp bend smoothly without damage. The results are shown in Table 1.
[0036] Table 1:
[0037] Combining the test results in Table 1 above, it can be seen that the snake-bone tubes prepared in this application exhibit high radial pressure bearing capacity, all exceeding 10N. Its straight support section can withstand large radial pressure without significant collapse, and the large-bending flexible section can smoothly pass through the sharp bends of the simulated cavity with a curvature radius of about 6mm, demonstrating excellent flexibility. Combining the test results of Examples 1 and 4, in Example 4, when the vanadium content was low and a higher heat treatment temperature was used, the radial pressure bearing capacity of its straight support section decreased, while the large-bending flexible section had a larger curvature radius when passing through the simulated cavity, resulting in reduced flexibility. Combining the test results of Examples 5-7, when a gradient magnetic field was applied during heat treatment, phase control was formed between the large-bending flexible section and the straight support section, improving the radial pressure bearing capacity of the straight support section and further enhancing the flexibility of the large-bending flexible section, achieving a stiffness distribution of "flexible at sharp bends and rigid at straight sections".
[0038] Furthermore, the austenitic phase transformation end temperature (Af point) of the snake-like tube prepared in Example 1, measured using differential scanning calorimetry (DSC), was 34.5°C, slightly lower than human body temperature. This ensures the snake-like tube remains soft and easily shaped at room temperature, facilitating surgical procedures. Upon insertion into the body, due to body temperature, the tube rapidly transforms into a strong, highly elastic austenitic phase, providing stable support. Additionally, the surface roughness (Ra) of the snake-like tube prepared in the above examples was measured using a white light interferometer, showing a value of 0.12-0.15. The snake-like tube prepared in these examples underwent gradient composite polishing, resulting in low roughness and excellent surface finish. This reduces frictional resistance and improves biocompatibility, allowing for smooth passage through cavities.
[0039] Ultimately, the snake-like tube fabricated in this embodiment can withstand radial pressure of ≥10N without significant collapse in its straight support section, effectively maintaining the unobstructed access of the instrument channel. Meanwhile, the large-bend soft section exhibits excellent flexibility, allowing it to smoothly pass through the sharp bends of a simulated cavity with a curvature radius of 6mm. Within a limited length, the snake-like tube fabricated in this embodiment achieves a gradient change in stiffness through the synergistic design of "zonal structure setting" and "spiral opening," combined with component-guided heat treatment and gradient polishing. This makes it suitable for minimally invasive interventional surgery scenarios with high requirements for dimensional flexibility and operational safety.
[0040] This specific embodiment is merely an explanation of this application and is not intended to limit it. 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 fall within the scope of the claims of this application.
Claims
1. A medical nickel-titanium alloy snake-bone tube, characterized in that, The system includes a snake-bone tube body, which comprises a large-bending flexible section, a transition balance section, and a straight support section distributed along the axial direction. The radius of curvature of the large-bending flexible section is ≤15mm. The snake-bone tube body has spiral openings, with the openings at the large-bending flexible section being elongated oval holes and the openings at the straight support section being circular holes. The hole size and density of the large-bending flexible section are greater than those of the straight support section, while the hole size and density of the transition balance section are between those of the large-bending flexible section and the straight support section. The openings on the snake bone tube body are arranged in a spiral staggered pattern, and the center lines of adjacent holes are circumferentially offset by 60°-120°.
2. The medical nickel-titanium alloy snake bone tube according to claim 1, characterized in that: The snake bone tube body comprises the following chemical components by weight percentage: 52-57% nickel, 0.2-2.8% vanadium, and the balance of titanium and unavoidable trace elements.
3. A method for preparing a medical nickel-titanium alloy snake-bone tube as described in claim 1 or 2, characterized in that: Includes the following steps: S1. Solution treatment is performed on the nickel-titanium serpentine tube matrix. S2. The solution-treated snake bone tube substrate is laser-cut to obtain a snake bone tube body with the hole distribution as described in claim 1. During laser cutting, an auxiliary gas is introduced and the pressure is maintained at 0.5-0.8 MPa. S3. The snake bone tube body after the hole is opened in step S2 is cold-bent and heat-treated to set its shape. S4. The snake bone tube body processed in step S3 is placed in a magnetic polishing machine for physical polishing, then immersed in a chemical polishing solution for chemical polishing, washed with water and dried to obtain a medical nickel-titanium alloy snake bone tube.
4. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: The solution treatment parameters in step S1 are: heat treatment at 850-900℃ for 30-40 minutes followed by water cooling.
5. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: When cutting large-sized elongated holes at the flexible section with large bends in step S2, a power of 140-150W and a speed of 50-70mm / s should be used. When cutting small-sized round holes at the straight support section, the power is 120-130W and the speed is 80-100mm / s.
6. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: The specific operation of cold bending in step S3 is as follows: the snake tube body processed in step S2 is installed on the shaping mold, the cold bending process is used to obtain the snake-shaped curved profile, and then it is kept at 300-350℃ for 10-20 minutes and then cooled in the furnace.
7. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: The specific operation of heat treatment and shaping in step S3 is as follows: When the vanadium content is 0.2-1.0wt%, keep warm at 510-520℃ for 10-20 minutes; When the vanadium content is 1.0-2.8wt%, keep warm at 480-500℃ for 25-40 minutes.
8. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: The chemical polishing solution in step S4 includes hydrofluoric acid with a volume fraction of 15-30%, nitric acid with a volume fraction of 15-30%, and the balance being water; Furthermore, chemical polishing involves immersion treatment at room temperature for 50-280 seconds.
9. The method for preparing a medical nickel-titanium alloy snake-bone tube according to claim 3, characterized in that: During heat treatment and shaping in step S3, an axial gradient magnetic field is applied to the snake-bone tube body. The magnetic field strength at the large bending flexible section is 0.4-0.6T, and the magnetic field strength at the straight support section is 0.1-0.2T.