Carbon fiber composite bone screw and method of making the same

Abstract

The application provides a carbon fiber composite bone screw and a preparation method thereof, and relates to the technical field of orthopedic implant devices.The carbon fiber composite bone screw is prepared by the following steps: preparing a spiral line by hot coiling of a shape memory alloy profile, cooling and straightening; preparing a braided sleeve by braiding of carbon fibers; equidistantly sewing the treated shape memory alloy profile to the surface of the braided sleeve along the axial direction, and matching the sewing interval with the pitch of the screw, so as to form a sewed braided sleeve; heating and heat-insulating the sewed braided sleeve, so as to form a bone screw structure braided sleeve preform; placing the preform into a cavity mold of a bone screw structure, injecting short-cut carbon fiber reinforced polyaryletherketone raw materials, cooling, demolding, heat treatment and temperature reduction, and then obtaining the carbon fiber composite bone screw.The shape memory alloy fiber is used as a configuration line to construct a screw surface with different curvatures, and the shape memory alloy fiber has the shape locking advantage; the braided structure on the surface of the finished bone screw forms a controllable concave-convex morphology, and the surface roughness is improved.

Description

Technical Field

[0001] This application relates to the field of orthopedic implant technology, and more specifically, to a carbon fiber composite bone screw and its preparation method. Background Technology

[0002] Bone screws are components of many bone implant structures, their main functions being fastening and load transfer. Currently, bone screws are mostly made of titanium alloys, magnesium alloys, and polymer materials, which are prone to fatigue fracture during in-body use. To enhance the mechanical properties of bone screws and improve their resistance to dislodgement, existing technologies include: Chinese invention patent CN116533550A discloses a processing technology for a cone-shaped screw based on carbon fiber reinforced polyetheretherketone (PEEK) material, including: injection molding and hot pressing: according to the pre-designed dimensions of the fixing part, extension part, nailing part, and nut, carbon fiber reinforced PEEK material is injection molded using an injection molding machine and hot-pressed at 120°C with a pressure of 3-5 MPa to obtain semi-finished products of the fixing part, extension part, nailing part, and nut, respectively, and pin holes are pre-drilled in the extension part and nut semi-finished products; embedding the developing pin: a first developing pin made of tantalum material is inserted into the pre-drilled pin hole in the nut semi-finished product, and the tantalum material is then embedded. The second developing pin, made of material, is inserted into the pre-reserved pinhole of the extension semi-finished product; Bioactive coating molding: The fixing semi-finished product, the extension semi-finished product, the nailing semi-finished product, and the nut semi-finished product are placed in a mineralizing solution with saturated sodium bicarbonate solution to perform bone-like apatite deposition, resulting in the fixing part, the extension part, the nailing part, and the nut; Assembly molding: A polylactic acid buffer plate is bonded to the top of the assembly cavity of the extension part, and one end of the high-elasticity memory alloy wire is welded to the polylactic acid buffer plate, and the other end is welded to the inner wall of the assembly cavity; The mounting block of the nailing part is screwed into the assembly cavity, and the nut is screwed into the thread groove and fixedly connected to the fixing part, resulting in a cone-shaped screw with a screw body and a nut.

[0003] This scheme uses carbon fiber reinforced polyetheretherketone (PEEK) material as the screw body, and bonds a polylactic acid buffer plate to the top of the assembly cavity of the extension and welds a high-elasticity shape memory alloy wire to enhance its mechanical properties. However, this preparation method does not achieve a good combination between the carbon fiber reinforcement material and the shape memory alloy material. The shape memory alloy material cannot play the role of dispersing the stress on the carbon fiber reinforcement material. When under pressure, the components tend to separate. Summary of the Invention

[0004] To address the aforementioned problems, this application employs a method for preparing carbon fiber composite bone screws, comprising the following steps: S1: The spiral is prepared by hot rolling of shape memory alloy profile and straightened after cooling to the point of martensitic transformation; S2: Prepare a woven sleeve by weaving carbon fiber; S3: The shape memory alloy profile processed in step S1 is sewn equidistantly along the axial direction onto the surface of the braided sleeve, and the sewing spacing is matched with the pitch to form a sewn braided sleeve. S4: Heat and insulate the sewn braided sleeve to form a prefabricated bone screw structure braided sleeve; S5: After placing the preform into the cavity mold of the bone screw structure, inject the short carbon fiber reinforced polyaryletherketone raw material, cool, demold, heat treat and cool down to obtain the carbon fiber composite bone screw.

[0005] Optionally, the shape memory alloy is a nickel-titanium based shape memory alloy, and the shape memory alloy profile is one of wire, sheet or tube; The diameter of the filament is 0.1-0.3 mm; The width and thickness of the sheet are 0.1-0.3 mm; The outer diameter of the pipe is 0.3 mm and the thickness is 0.1 mm. In step S1, before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical profile formed by its spiral. In step S3, the position of the mark is made tangent to the inner surface of the cylindrical profile formed by the sewn shape memory alloy profile.

[0006] Optionally, the nickel-titanium-based shape memory alloy contains 54.5%-57.0% nickel by mass, and the mass fraction of impurity elements is required to be ≤0.040% carbon, ≤0.050% cobalt, ≤0.010% copper, ≤0.010% chromium, ≤0.005% hydrogen, ≤0.050% iron, ≤0.025% niobium, ≤0.005% nitrogen, and ≤0.040% oxygen, with the balance being titanium. The martensitic transformation completion temperature of the nickel-titanium-based shape memory alloy is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0007] Optionally, the hot rolling forming in step S1 includes heating the shape memory alloy profile to 400-500°C and then placing it in a roller device to perform hot rolling forming at a winding speed of 2-10 mm / s, a winding force of 1-10 N, and a winding diameter of 3.0-8.0 mm. The cooling conditions are: air is allowed to cool naturally to room temperature, and then forced to cool until the martensitic transformation is complete; Before the stitching is completed in step S3, the temperature of the shape memory alloy profile is maintained at the temperature after cooling.

[0008] Optionally, in step S2, the diameter of the carbon fiber is 5-10 μm, the carbon fiber is twisted or partially twisted, and the braiding method of the braided sleeve is 2D braiding or 3D braiding. The 2D braided structure is a 2×2, 1×1, 3×3 or 2×1 tubular two-dimensional triaxial braided sleeve; both the braided yarn and the axial yarn are carbon fiber, the braided yarn width is 0.5mm when at rest, the braiding angle is 30-60°, there are 64 spindles and 32 axial yarns, the coverage coefficient is ≥90%, and the braiding pitch is 5-8mm; The 3D woven set uses a four-step method to weave in one of the following three dimensions: four-dimensional, five-dimensional, six-dimensional, or seven-dimensional. The weaving angle ranges from 10 to 45°, the knot length is 0.5 to 11.5 mm, and the knot width is 0.5 to 2.0 mm. Step S2 further includes drying the braided sleeve to a moisture content of less than 0.1% by mass, and then cooling it to below the martensitic transformation temperature of the shape memory alloy profile. The braided sleeve is kept at this cooled temperature until the stitching is completed in step S3.

[0009] Optionally, After completing step S4 and before proceeding to step S5, the process includes placing a continuous carbon fiber-polyetheretherketone (PEEK) core inside the stitch-woven sleeve. The melt index of the PEEK core in the continuous carbon fiber-PEEK core is 76 g / 10 min under the conditions of 380°C and 5 kg load. The fiber volume content of the continuous carbon fiber-PEEK core is 60%. The test is conducted based on the fiber orientation direction. The tensile strength of the continuous carbon fiber-PEEK core is ≥2000 MPa, the compressive strength is ≥1250 MPa, and the short beam shear strength is ≥90 MPa.

[0010] Optionally, the stitching includes single-helix stitching and double-helix stitching; The single spiral stitching involves spirally stitching a first shape memory alloy profile along the axial direction at intervals of 1.5-5.0 mm to the surface of the carbon fiber braided sleeve, and then alternately stitching a second shape memory alloy profile with the same intervals to the first shape memory alloy profile. The double helix stitching involves alternately spirally stitching the first and second shape memory alloy profiles along the axial direction at intervals of 1.5-5.0 mm to the surface of the carbon fiber braided sleeve, and then alternately stitching the third and fourth shape memory alloy profiles with the first and second shape memory alloy profiles at the same intervals. The material is sewn onto the surface of the carbon fiber braided sleeve, including the outer surface, the inner surface, or the outer and inner surfaces interlaced, with the winding direction being clockwise or counterclockwise.

[0011] Optionally, step S4, heating and heat preservation, includes: heating the braided sleeve to a temperature of 100-150°C and then holding it at that temperature for 5-15 minutes, with the heating rate not exceeding 10°C / min.

[0012] Optionally, in step S5, the chopped carbon fiber reinforced polyaryletherketone resin is selected from either chopped carbon fiber reinforced polyetheretherketone or chopped carbon fiber reinforced polyetherketone ketone, and the fiber mass content in the chopped carbon fiber reinforced polyaryletherketone resin is 30% ± 2%. Injection molding temperature: 360℃-400℃, hot runner temperature control system temperature: 350℃-380℃, mold temperature: 150-200℃, injection pressure: 80-200MPa, injection rate: 50-400mm / s; The heat treatment temperature is 170-250℃, the duration is 2-12h, the cooling rate is 0.2-2℃ / min, the temperature after cooling is 120-160℃, and then it is naturally cooled to room temperature.

[0013] This application also provides a carbon fiber composite bone screw, which is prepared using any of the aforementioned carbon fiber composite bone screw preparation methods, and includes: a structural reinforcement skeleton and a structural matrix; The structural reinforcement skeleton is a stitch-woven sleeve, which is formed by stitching shape memory alloy profiles equidistantly along the axial direction onto the surface of the sleeve, ensuring that the stitch spacing matches the pitch; the sleeve is made of carbon fiber braiding. The structural matrix is ​​short-cut carbon fiber reinforced polyaryletherketone.

[0014] The beneficial effects of the carbon fiber composite bone screw and its preparation method provided in this application are as follows: (1) This application uses shape memory alloy fibers as configuration lines, which can construct screw surfaces with different curvatures and has the advantage of shape locking; it can locate screw contours in CT and MRI imaging. (2) The mesh braided sleeve structure design of this application distributes the load evenly on the bone-screw interface when subjected to periodic loads, which can effectively reduce the incidence of screw fracture. (3) The prefabricated bone screw structure braided sleeve is based on continuous fiber braided sleeve and shape memory alloy configuration line as a reinforcing skeleton. It can guide the short carbon fiber reinforced polyaryletherketone raw material to fill the mold cavity and the interior of the bone screw structure braided sleeve evenly, so that the reinforcing structure and configuration line of the prefabricated body are fully impregnated and wrapped, maximizing the interface bonding area between the reinforcing body and the matrix, and improving the mechanical properties of carbon fiber composite bone screws such as shear resistance and fatigue resistance. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0016] Figure 1 This is a schematic diagram of the cylindrical outline and markings formed by the spiral lines provided in the embodiments of this application; Figure 2This is a schematic diagram of a single spiral stitch-woven shape memory alloy profile stitched to the inner surface of a carbon fiber braided sleeve, provided in an embodiment of this application (hidden lines are visible). Figure 3 yes Figure 2 AA section view; Figure 4 This is a schematic diagram of the single spiral stitch-woven shape memory alloy profile stitched to the outer surface of the carbon fiber braided sleeve provided in the embodiments of this application (hidden lines are visible); Figure 5 yes Figure 4 AA section view; Figure 6 This is a schematic diagram (hidden lines are visible) of the double helix stitch-woven shape memory alloy profile stitched to the inner and outer surfaces of the carbon fiber braided sleeve, provided in the embodiments of this application. Figure 7 yes Figure 6 AA section view; Figure 8 This is a schematic diagram of the double helix stitched shape memory alloy profile stitched to the outer surface of the carbon fiber braided sleeve provided in the embodiments of this application (hidden lines are visible); Figure 9 yes Figure 8 AA section view; Figure 10 This is a schematic diagram of the prefabricated bone screw structure provided in the embodiments of this application; Figure 11 yes Figure 10 AA section view; Figure 12 This is a schematic diagram of the carbon fiber bone screw structure provided in the embodiments of this application (short-cut carbon fiber reinforced with polyaryletherketone external filling to form threads). Figure 13 yes Figure 12 AA sectional view.

[0017] Figure 14 This is a schematic diagram of the carbon fiber bone screw structure provided in the embodiments of this application (short-cut carbon fiber reinforced with polyaryletherketone external filling to form threads and cover the surface). Figure 15 yes Figure 14 AA section view; Figure 16 This is a schematic diagram of the orientation direction of the continuous carbon fiber-polyetheretherketone core provided in the embodiments of this application.

[0018] Explanation of reference numerals in the attached figures: 1-Hot-rolled spiral; 2-Inner surface of cylindrical profile; 3-Outer surface of cylindrical profile; 4-Marking line; 5-First shape memory alloy profile; 6-Second shape memory alloy profile; 7-Third shape memory alloy profile; 8-Fourth shape memory alloy profile; 9-Carbon fiber braided sleeve; 10-Short-cut carbon fiber reinforced polyaryletherketone inner filling; 11-Short-cut carbon fiber reinforced polyaryletherketone outer filling; 12-Continuous carbon fiber-polyetheretherketone inner core. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] This application provides a method for preparing carbon fiber composite bone screws, comprising the following steps: S1: The shape memory alloy profile is hot-rolled to form a spiral, and then straightened after cooling to the point of martensitic transformation.

[0021] Shape memory alloys are nickel-titanium based shape memory alloys, and shape memory alloy profiles are one of the following: wires, sheets, or tubes; The diameter of the filament is 0.1-0.3 mm; The width and thickness of the sheet are 0.1-0.3 mm; The outer diameter of the pipe is 0.3 mm and the thickness is 0.1 mm. In step S1, before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical profile formed by its spiral. In step S3, the position of the mark is made tangent to the inner surface of the cylindrical profile formed by the sewn shape memory alloy profile.

[0022] To ensure that the winding direction of the shape memory alloy profile is consistent with the winding direction during stitching during the hot rolling process, the spiral prepared by the hot rolling method is first marked after cooling, such as... Figure 1 As shown, the outer contour of the hot-rolled spiral 1 can be regarded as a cylindrical structure with an inner cylindrical contour surface 2 and an outer cylindrical contour surface 3. A marking line 4 is made at the position where the hot-rolled spiral 1 is tangent to the inner cylindrical contour surface 2.

[0023] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0024] Hot rolling involves heating the shape memory alloy profile to 400-500℃, then placing it in a roller device for hot rolling at a winding speed of 2-10mm / s, a winding force of 1-10N, and a winding diameter of 3.0-8.0mm. The cooling conditions are: air is allowed to cool naturally to room temperature, and then forced to cool until the martensitic transformation is complete; Before the stitching is completed in step S3, the temperature of the shape memory alloy profile is maintained at the temperature after cooling.

[0025] The purpose of hot rolling shape memory alloy profiles is to allow the shape memory alloy profiles to remember the structure of the bone screws being prepared. When the shape memory alloy profiles include a first shape memory alloy profile 5 and a second shape memory alloy profile 6, the thread pitch of the first shape memory alloy profile 5 is consistent with the thread pitch of the bone screw, and it serves as the thread support base in the prefabricated braided sleeve body of the bone screw structure. The thread pitch of the second shape memory alloy profile 6 is consistent with that of the first shape memory alloy profile 5, and it serves as the screw support base in the prefabricated braided sleeve body of the bone screw structure.

[0026] S2: Prepare a woven sleeve by weaving carbon fiber.

[0027] The carbon fiber has a diameter of 5-10μm and is twisted or partially twisted. The braided sleeve is woven in 2D or 3D.

[0028] The 2D braided structure is a 2×2, 1×1, 3×3 or 2×1 tubular two-dimensional triaxial braided sleeve; both the braided yarn and the axial yarn are carbon fiber, the braided yarn width is 0.5mm when at rest, the braiding angle is 30-60°, there are 64 spindles and 32 axial yarns, the coverage coefficient is ≥90%, and the braiding pitch is 5-8mm; The 3D woven set uses a four-step method to weave in one of the following three dimensions: four-dimensional, five-dimensional, six-dimensional, or seven-dimensional. The weaving angle ranges from 10 to 45°, the knot length is 0.5 to 11.5 mm, and the knot width is 0.5 to 2.0 mm.

[0029] The woven sleeve is dried until the moisture content is below 0.1%, and then cooled to below the martensitic transformation temperature of the shape memory alloy profile. The woven sleeve is kept at this cooled temperature until the stitching is completed in step S3.

[0030] S3: The shape memory alloy profile processed in step S1 is axially and equidistantly stitched onto the surface of the braided sleeve, ensuring that the stitching spacing matches the pitch, thus forming a stitched braided sleeve. In this application, "stitched onto the surface of the braided sleeve" means that the stitching position of the shape memory alloy profile is close to the surface of the braided sleeve (including the inner and outer surfaces), and it is not required that the shape memory alloy profile be directly exposed outside the surface of the braided sleeve or directly interpenetrate with the outermost carbon fiber layer of the braided sleeve.

[0031] Stitching includes single-helix stitching and double-helix stitching; The single spiral stitching involves spirally stitching the first shape memory alloy profile 5 along the axial direction at a spacing of 1.5-5.0 mm to the surface of the carbon fiber braided sleeve 9, and alternately stitching the second shape memory alloy profile 6 with the first shape memory alloy profile 5 at the same spacing; the pitch of the first shape memory alloy profile 5 and the second shape memory alloy profile 6 after stitching is the same.

[0032] like Figures 2-5 As shown, Figures 2 to 5 It demonstrates a stitching method that uses a single spiral to ultimately form a single thread.

[0033] Figure 2 and Figure 3 This demonstrates the stitch-woven sleeve structure after the first shape memory alloy profile 5 and the second shape memory alloy profile 6 are stitched onto the outer surface of the carbon fiber braided sleeve 9, wherein, as Figure 10 and Figure 11 As shown, the first shape memory alloy profile 5 is used to form the thread support base of the preformed bone screw structure braided sleeve, and the second shape memory alloy profile 6 is used to form the screw support base of the preformed bone screw structure braided sleeve.

[0034] Figure 4 and Figure 5 The stitch-woven sleeve structure is shown after the first shape memory alloy profile 5 and the second shape memory alloy profile 6 are stitched onto the inner surface of the carbon fiber braided sleeve 9. The first shape memory alloy profile 5 is used to form the thread support base of the bone screw structure braided sleeve preform, and the second shape memory alloy profile 6 is used to form the screw support base of the bone screw structure braided sleeve preform.

[0035] The double helix stitching includes taking the first memory alloy profile 5 and the second memory alloy profile 6 as the starting point of the stitching along the axial direction with a difference of 180°, and alternately spirally stitching them onto the surface of the carbon fiber braided sleeve 9 at a spacing of 1.5-5.0mm. The third memory alloy profile 7 and the fourth memory alloy profile 8 are alternately stitched with the first memory alloy profile 5 and the second memory alloy profile 6 respectively, with the same spacing. like Figures 6 to 9 As shown, Figures 6 to 9 It demonstrates a stitching method that uses double helix stitching to ultimately form a double spiral stitch.

[0036] Figure 6 and Figure 7 The diagram illustrates a stitch-braided sleeve structure where a first shape memory alloy profile 5 and a second shape memory alloy profile 6 are stitched to the outer surface of a carbon fiber braided sleeve 9, and a third shape memory alloy profile 7 and a fourth shape memory alloy profile 8 are stitched to the inner surface of the carbon fiber braided sleeve 9. The first shape memory alloy profile 5 and the second shape memory alloy profile 6 are used to form the thread support base of the bone screw structure braided sleeve preform, and the third shape memory alloy profile 7 and the fourth shape memory alloy profile 8 are used to form the screw support base of the bone screw structure braided sleeve preform.

[0037] Figure 8 and Figure 9 The structure of the stitch-woven sleeve after the first shape memory alloy profile 5, the second shape memory alloy profile 6, the third shape memory alloy profile 7 and the fourth shape memory alloy profile 8 are stitched to the outer surface of the carbon fiber braided sleeve 9 is shown. The first shape memory alloy profile 5 and the second shape memory alloy profile 6 are used to form the thread support base of the bone screw structure braided sleeve preform, and the third shape memory alloy profile 7 and the fourth shape memory alloy profile 8 are used to form the screw support base of the bone screw structure braided sleeve preform.

[0038] The fibers are sewn onto the surface of the carbon fiber braided sleeve 9, including the outer surface, the inner surface, or the outer and inner surfaces interlaced, with the winding direction being clockwise or counterclockwise.

[0039] S4: Heat and insulate the sewn braided sleeve to form a prefabricated bone screw structure braided sleeve.

[0040] Step S4, heating and heat preservation, includes heating the braided sleeve to a temperature of 100-150℃ and then holding it at that temperature for 5-15 minutes, with the heating rate not exceeding 10℃ / min.

[0041] The resulting bone screw structure braided sleeve prefabricated body, such as Figures 10-11 As shown.

[0042] S5: After placing the preform into the cavity mold of the bone screw structure, inject the short carbon fiber reinforced polyaryletherketone raw material, cool, demold, and heat treat to obtain the carbon fiber bone screw.

[0043] The resulting carbon fiber bone screws, such as Figures 12-13 As shown, the carbon fiber braided sleeve 9 is filled with short-cut carbon fiber reinforced polyaryletherketone inner filler 10, forming the head, head, and internal hexagonal groove of the bone screw. The carbon fiber braided sleeve 9 is filled with short-cut carbon fiber reinforced polyaryletherketone outer filler 11, forming the edge of the thread. Figures 14-15As shown, in this embodiment, the short-cut carbon fiber reinforced polyaryletherketone external filler 11, in addition to forming the threaded edges, substantially covers the outer surface of the carbon fiber braided sleeve 9, compared to Figures 12-13 As shown, this solution requires positioning the lower edge of the carbon fiber braided sleeve 9 in the mold to ensure that the short carbon fiber reinforced polyaryletherketone exfill 11 evenly covers the outer surface of the formed carbon fiber bone screw.

[0044] Whether Figures 12-13 The situation shown is still Figures 14-15 As shown, the braided structure can form a controllable uneven morphology on the surface of the finished bone screw through a unique fiber interlacing design, directly improving the surface roughness. The structural design determines the roughness characteristics: the edges and gaps formed by the intersection of 2D braided fiber yarns constitute macroscopic rough texture; 3D braiding makes the surface form a three-dimensional mesh unevenness.

[0045] Increased surface roughness directly enhances the bone-screw interface, increasing the contact area between bone tissue and the screw, while simultaneously creating mechanical engagement points. This significantly improves axial pull-out force, effectively addressing the problem of screw loosening leading to failure in clinical practice. Adjustable surface roughness allows for adaptation to different implantation scenarios, including cancellous bone and cortical bone, providing both ease of implantation and long-term fixation stability.

[0046] The chopped carbon fiber reinforced polyaryletherketone resin is selected from either chopped carbon fiber reinforced polyetheretherketone or chopped carbon fiber reinforced polyetherketone ketone, and the fiber mass content in the chopped carbon fiber reinforced polyaryletherketone resin is 30%±2%; Injection molding temperature: 360℃-400℃; hot runner temperature control system temperature: 350℃-380℃; mold temperature: 150-200℃; injection pressure: 80-200MPa; injection rate: 50-400mm / s. The heat treatment temperature is 170-250℃, the duration is 2-12h, the cooling rate is 0.2-2℃ / min, the temperature after cooling is 120-160℃, and then it is naturally cooled to room temperature.

[0047] This application also provides a carbon fiber composite bone screw, which is prepared using any of the aforementioned carbon fiber composite bone screw preparation methods, and includes: a structural reinforcement skeleton and a structural matrix; The structural reinforcement skeleton is a stitch-woven sleeve, which is formed by stitching shape memory alloy profiles equidistantly along the axial direction onto the surface of the sleeve, ensuring that the stitch spacing matches the pitch; the sleeve is made of carbon fiber braiding. The structural matrix is ​​short-cut carbon fiber reinforced polyaryletherketone.

[0048] The carbon fiber specification is T700S-12K.

[0049] Example 1: Step S1: Two nickel-titanium shape memory alloy wire profiles, each with a diameter of 0.1 mm, are heated to 400°C. The first shape memory alloy profile is then hot-rolled into a first shape memory alloy spiral using a roller device with a winding force of 1 N, a winding speed of 2 mm / s, a winding diameter of 8.0 mm, and a spacing of 1.5 mm. The second shape memory alloy profile is then hot-rolled into a second shape memory alloy spiral using a winding force of 1 N, a winding speed of 2 mm / s, a winding diameter of 6 mm, and a spacing of 1.5 mm. The spiral is then allowed to cool naturally to room temperature and then forced to cool below the martensitic transformation completion temperature before straightening. In this embodiment, the temperature of the spiral before straightening is -10°C. Before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical contour formed by its spiral. In step S3, this mark is kept tangent to the inner surface of the cylindrical contour formed by the stitched shape memory alloy profile.

[0050] Before the stitching in step S3 is completed, the temperature of the shape memory alloy profile is maintained at -10℃.

[0051] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0052] Step S2: Partially twisted carbon fiber yarn with a rest width of 0.5mm is braided in a 2×2 structure with a braiding angle of 30°, 64 spindles, a braiding pitch of 5mm, and a coverage factor of 90% to produce a conical carbon fiber braided sleeve with a carbon fiber diameter of 5μm. After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0053] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the carbon fiber braided sleeve at a 1.5mm interval and clockwise around the axis. The second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same interval and alternately sewn with the first straightened alloy wire. The two alloy wires are on the same axis and the spacing between the two alloy wires is consistent, thus obtaining the sewn braided sleeve. The sewing process is carried out at -10℃.

[0054] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 150℃, molding temperature 360℃, hot runner temperature 350℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 80MPa, injection speed 50mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 170℃ for 2 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions are 380℃ and 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 120℃ at a rate of 0.2℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0055] Example 2: Step S1: After heating four nickel-titanium shape memory alloy wire profiles, each with a diameter of 0.3 mm, to 450°C, the first and second shape memory alloy profiles are hot-rolled into first and second shape memory alloy spirals on a roller device with a winding force of 3N, a winding speed of 4 mm / s, a winding diameter of 5.0 mm, and a spacing of 3 mm. The third and fourth shape memory alloy profiles are then hot-rolled into third and fourth shape memory alloy spirals with a winding force of 3N, a winding speed of 4 mm / s, a winding diameter of 3.0 mm, and a spacing of 3 mm. After natural cooling to room temperature, they are then forced to cool to below the martensitic transformation completion temperature and straightened. In this embodiment, the temperature of the spiral before straightening is -10°C. Before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical contour formed by its spirals. In step S3, this mark is kept tangent to the inner surface of the cylindrical contour formed by the stitched shape memory alloy profile.

[0056] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0057] Step S2: All the twisted carbon fiber yarns with a rest width of 0.5 mm are braided in a 1×1 structure with a braiding angle of 40°, 64 spindles, a braiding pitch of 6 mm, and a coverage factor of 99% to produce a conical carbon fiber braided sleeve with a carbon fiber diameter of 5 μm. After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0058] Step S3: The first, third, second, and fourth straightened alloy wires are sequentially helically sewn into the inner surface of the carbon fiber braided sleeve with the same spacing and a pitch of 3 mm, and the four alloy wires are on the same axis with equal spacing to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0059] Step S4: After heating the suture braided sleeve at 125℃ for 10 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min.

[0060] Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 160℃, molding temperature 370℃, hot runner temperature 360℃), short-cut carbon fiber reinforced polyetherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 100MPa, injection speed 150mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 190℃ for 4 hours. The melt index of the short-cut carbon fiber reinforced polyetherketone resin is 17g / 10min (test conditions are 380℃, 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetherketone resin is 30%. Then, the temperature is reduced to 130℃ at a rate of 0.5℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0061] Example 3: Step S1: Two nickel-titanium shape memory alloy wire tubes with an outer diameter of 0.3 mm and a thickness of 0.1 mm are heated to 500°C. The first shape memory alloy profile is then hot-rolled into a first shape memory alloy spiral using a roller device with a winding force of 5 N, a winding speed of 6 mm / s, a winding diameter of 5.0 mm, and a spacing of 4 mm. The second shape memory alloy profile is then hot-rolled into a second shape memory alloy spiral using a winding force of 5 N, a winding speed of 6 mm / s, a winding diameter of 3.0 mm, and a spacing of 4 mm. After natural cooling to room temperature, the spiral is then forced to cool below the martensitic transformation completion temperature and straightened. In this embodiment, the temperature of the spiral before straightening is -10°C. Before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical profile formed by its spiral. In step S3, this mark is kept tangent to the inner surface of the cylindrical profile formed by the stitched shape memory alloy profile.

[0062] Before the stitching in step S3 is completed, the temperature of the shape memory alloy profile is maintained at -10℃. The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0063] Step S2: Partially twisted carbon fiber yarn with a rest width of 0.5 mm is braided in a 3×3 structure with a braiding angle of 50°, 64 spindles, a braiding pitch of 7 mm, and a coverage factor of 90% to produce a conical carbon fiber braided sleeve with a carbon fiber diameter of 5 μm. After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0064] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the carbon fiber braided sleeve at a 4mm interval, and the second straightened alloy wire is sewn into the inner surface of the braided sleeve at the same interval, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the interval is equal, thus obtaining the sewn braided sleeve. The sewing process is carried out at -10℃.

[0065] Step S4: After heating the suture braided sleeve at 150℃ for 15 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is pre-placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 170℃, molding temperature 380℃, hot runner temperature 370℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 120MPa, injection speed 250mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 210℃ for 6 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions: 380℃, 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 140℃ at a rate of 1℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0066] Example 4: Step S1: Two nickel-titanium shape memory alloy wire tubes with an outer diameter of 0.3 mm and a thickness of 0.1 mm are heated to 400°C. The first shape memory alloy profile is then hot-rolled into a first shape memory alloy spiral using a roller device with a winding force of 7 N, a winding speed of 8 mm / s, a winding diameter of 6.0 mm, and a spacing of 5 mm. The second shape memory alloy profile is then hot-rolled into a second shape memory alloy spiral using a winding force of 7 N, a winding speed of 8 mm / s, a winding diameter of 4.2 mm, and a spacing of 5 mm. After natural cooling to room temperature, the spiral is then forced to cool below the martensitic transformation completion temperature and straightened. In this embodiment, the temperature of the spiral before straightening is -10°C. Before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical profile formed by its spiral. In step S3, this mark is kept tangent to the inner surface of the cylindrical profile formed by the stitched shape memory alloy profile.

[0067] Before the stitching in step S3 is completed, the temperature of the shape memory alloy profile is maintained at -10℃.

[0068] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0069] Step S2: Partially twisted carbon fiber yarn with a rest width of 0.5 mm is braided in a 2×1 structure with a braiding angle of 60°, 64 spindles, a braiding pitch of 8 mm, and a coverage factor of 90% to produce a conical carbon fiber braided sleeve with a carbon fiber filament diameter of 5 μm. After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0070] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the above carbon fiber braided sleeve at a 5mm interval, and the second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same interval, and is alternately sewn with the first straightened alloy wire. The starting point of the two alloy wires is on the same axis and the interval is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0071] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 180℃, molding temperature 390℃, hot runner temperature 380℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 160MPa, injection speed 350mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 230℃ for 8 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions: 380℃, 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 150℃ at a rate of 1.5℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0072] Example 5: Step S1: Two nickel-titanium shape memory alloy wire sheets, each 0.1 mm thick and wide with a square cross-section, are heated to 400°C. The first shape memory alloy profile is then hot-rolled into a first shape memory alloy spiral using a roller device with a winding force of 10 N, a winding speed of 10 mm / s, a winding diameter of 5.0 mm, and a spacing of 1.5 mm. The second shape memory alloy profile is then hot-rolled into a second shape memory alloy spiral using the same winding force of 10 N, a winding speed of 10 mm / s, a winding diameter of 3.0 mm, and a spacing of 1.5 mm. After natural cooling to room temperature, the spiral is then forced to cool below the martensitic transformation completion temperature and straightened. In this embodiment, the spiral temperature before straightening is -10°C. Before straightening, a mark is made on the shape memory alloy profile at a position tangent to the inner surface of the cylindrical profile formed by the spiral. In step S3, this mark is kept tangent to the inner surface of the cylindrical profile formed by the stitched shape memory alloy profile.

[0073] Before the stitching in step S3 is completed, the temperature of the shape memory alloy profile is maintained at -10℃.

[0074] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0075] Step S2: Partially twisted carbon fiber yarn with a rest width of 0.5mm is braided in a 2×2 structure with a braiding angle of 30°, 64 spindles, a braiding pitch of 5mm, and a coverage factor of 90% to produce a conical carbon fiber braided sleeve with a carbon fiber diameter of 5μm. After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0076] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the above carbon fiber braided sleeve at a spacing of 1.5mm in a clockwise direction around the axis. The second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same spacing in a clockwise direction, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the spacing is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0077] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 190℃, molding temperature 400℃, hot runner temperature 380℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 180MPa, injection speed 400mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 250℃ for 10 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions are 380℃ and 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 160℃ at a rate of 2℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0078] Example 6: The difference between this embodiment and Embodiment 1 is that the selected nickel-titanium shape memory alloy wire is two nickel-titanium shape memory alloy wire sheets with a thickness of 0.3 mm, a width of 0.3 mm, and a square cross-section. The processes in step S1 are completely consistent with those in Embodiment 1.

[0079] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0080] Step S2: Using a four-step method, partially twisted carbon fiber yarn with a rest width of 0.5 mm is woven in three dimensions and four directions with a weaving angle of 10°, a knot length of 0.5 mm, and a knot width of 0.5 mm, to produce a conical carbon fiber woven sleeve. First straightened alloy wires are spirally sewn into the outer surface of the carbon fiber woven sleeve at 1.5 mm intervals, clockwise around the axis. Second straightened alloy wires are sewn into the outer surface of the woven sleeve at the same interval, alternating with the first straightened alloy wires. The starting points of the two alloy wires are on the same axis with equal spacing, resulting in a sewn woven sleeve with a carbon fiber diameter of 5 μm.

[0081] After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0082] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the above carbon fiber braided sleeve at a spacing of 1.5mm in a clockwise direction around the axis. The second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same spacing in a clockwise direction, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the spacing is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0083] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 200℃, molding temperature 360℃, hot runner temperature 350℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 200MPa, injection speed 50mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 170℃ for 12 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions are 380℃, 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 120℃ at a rate of 0.2℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0084] Example 7: This embodiment is completely identical to Embodiment 1 in step S1.

[0085] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0086] Step S2: Using a four-step method, partially twisted carbon fiber yarn with a rest width of 0.5 mm is woven in three dimensions and five directions with a weaving angle of 15°, a knot length of 3 mm, and a knot width of 1 mm to produce a conical carbon fiber woven sleeve with a carbon fiber diameter of 5 μm.

[0087] After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0088] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the carbon fiber braided sleeve at a 1.5mm interval, and the second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same interval, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the distance between them is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0089] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. Step S5: The preform is placed into the mold of the final bone screw structure. After the injection molding machine, mold temperature controller, and hot runner temperature control box reach the specified temperatures and achieve uniform heating (mold temperature 150℃, molding temperature 360℃, hot runner temperature 350℃), short-cut carbon fiber reinforced polyetheretherketone resin is injected into the mold cavity under the corresponding process conditions (injection pressure 200MPa, injection speed 50mm / s). After cooling and demolding, it is placed in a precision oven for heat treatment at 170℃ for 2 hours. The melt index of the short-cut carbon fiber reinforced polyetheretherketone resin is 20g / 10min (test conditions are 380℃ and 5kg load), and the fiber mass content in the short-cut carbon fiber reinforced polyetheretherketone resin is 30%. Then, the temperature is reduced to 120℃ at a rate of 0.2℃ / min, the oven power is turned off, and it is allowed to cool naturally to room temperature to obtain the carbon fiber composite bone screw.

[0090] Example 8: This embodiment is completely identical to Embodiment 1 in step S1.

[0091] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0092] Step S2: Using a four-step method, partially twisted carbon fiber yarn with a rest width of 0.5 mm is woven in three dimensions and six directions with a weaving angle of 30°, a knot length of 6 mm, and a knot width of 1.5 mm to produce a conical carbon fiber woven sleeve with a carbon fiber filament diameter of 5 μm.

[0093] After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0094] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the carbon fiber braided sleeve at a 1.5mm interval, and the second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same interval, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the distance between them is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0095] Step S4: After heating the suture braided sleeve at 100℃ for 5 minutes, remove it to form a prefabricated bone screw structure braided sleeve. The heating rate should not exceed 10℃ / min. This embodiment is completely identical to Embodiment 1 in step S5.

[0096] Example 9: This embodiment is completely identical to Embodiment 1 in step S1.

[0097] The nickel mass fraction in nickel-titanium-based shape memory alloys is 54.5%-57.0%, and the mass fraction requirements for impurity elements are: carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, with the balance being titanium. The martensitic transformation completion temperature of nickel-titanium-based shape memory alloys is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

[0098] Step S2: Using a four-step method, partially twisted carbon fiber yarn with a rest width of 0.5 mm is woven in three dimensions and seven directions with a weaving angle of 45°, a knot length of 11.5 mm, and a knot width of 2 mm to produce a conical carbon fiber woven sleeve with a carbon fiber filament diameter of 5 μm.

[0099] After the braided cover is finished, it is vacuum dried at 60°C for 24 hours. After sampling and testing, the moisture content is found to be less than 0.1%. Then, it is cooled to -10°C. Before the sewing is completed in step S3, the braided cover is kept at this cooled temperature.

[0100] Step S3: The first straightened alloy wire is spirally sewn into the outer surface of the carbon fiber braided sleeve at a 1.5mm interval, and the second straightened alloy wire is sewn into the outer surface of the braided sleeve at the same interval, and is alternately sewn with the first straightened alloy wire. The starting points of the two alloy wires are on the same axis and the distance between them is equal, so as to obtain the sewn braided sleeve. The sewing process is carried out at -10℃.

[0101] Step S4: The suture braided sleeve containing the continuous carbon fiber-polyetheretherketone (PEEK) core is heated at 100°C for 5 minutes and then removed to form a prefabricated bone screw structure braided sleeve. After completing Step S4 and before proceeding to Step S5, the continuous carbon fiber-PEEK core is placed inside the suture braided sleeve. The melt index of the PEEK core in the continuous carbon fiber-PEEK core is tested at 380°C and under a 5kg load, and the result is 76g / 10min. The fiber volume content of the continuous carbon fiber-PEEK core is 60%.

[0102] like Figure 16As shown in the figure, the direction pointed to by the arrow is 0°, that is, the direction along the length of the continuous carbon fiber-polyetheretherketone core is defined as 0°. This direction is the fiber orientation direction of the continuous carbon fiber-polyetheretherketone core. The continuous carbon fiber-polyetheretherketone core is prepared by pultrusion or hot pressing of unidirectional prepreg and then mechanical processing. With the fiber orientation direction as the test benchmark, the tensile strength at 0° is ≥2000MPa, the compressive strength at 0° is ≥1250MPa, and the short beam shear strength at 0° is ≥90MPa.

[0103] This embodiment is completely identical to Embodiment 1 in step S5.

[0104] The experimental process parameters of the carbon fiber composite bone screws prepared in Examples 1-9 are shown in Tables 1-4.

[0105] Table 1. Profile processing parameters in step S1 of Examples 1-9

[0106] Table 2. Process parameters for the preparation of braided sleeves in step S2 of Examples 1-9

[0107] Table 2 (continued) Process parameters for the preparation of braided sleeves in step S2 of Examples 1-9

[0108] Table 3. Process parameters for steps S3-S4 of Examples 1-9: preparation of stitch-woven sleeves and prefabricated bone screw structure sleeves.

[0109] Table 4. Process parameters for the fabrication of carbon fiber bone screws in step S5 of Examples 1-9

[0110] Comparative Example 1: Titanium alloy bone screws are manufactured using CNC machine tools through turning and milling processes. Appropriate threading cutters, V-cutters, milling cutters, parting cutters, and titanium alloy finishing rods are selected and installed in their respective positions. The screw tip and thread outer diameter are precision turned sequentially at a speed of 2500 rpm and a feed rate of F0.02 mm / r; the thread is then precision turned at a speed of 800 rpm and a feed rate of F2.75 mm / r; and the ball end is precision turned at a speed of 3000 rpm and a feed rate of F0.02 mm / r. After machining, the parts are transferred to the fitter's workshop for preliminary treatment (removal of residual burrs and rounding), post-treatment, fine cleaning, and drying to obtain the titanium alloy bone screws.

[0111] The performance of the carbon fiber composite bone screws prepared in Examples 1-9 and the titanium alloy bone screws prepared in Comparative Example 1 were tested, and the results are shown in Table 5.

[0112] The bending / pull-out performance test method is conducted in accordance with YY / T0119.5-2014 Spinal Internal Fixation System Components Part 5: Test Method for Static and Fatigue Bending Strength of Metal Spinal Screws; The fracture toughness test method was conducted according to GB / T4161-2007, the KIC test method for plane strain fracture toughness of metallic materials.

[0113] Table 5 Performance test results of Examples 1-9 and Comparative Example 1

[0114] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method of manufacturing a carbon fiber composite bone screw, the method comprising: providing a carbon fiber composite material; providing a bone screw; and coupling the carbon fiber composite material to the bone screw. The method comprises the following steps: S1: preparing a helix by hot coiling forming of a shape memory alloy profile, and straightening the helix after cooling to complete martensitic transformation; S2: preparing a braided sleeve by braiding of carbon fibers; S3: equidistantly stitching the shape memory alloy profile treated in step S1 to the surface of the braided sleeve in the axial direction, and matching the stitching interval with the helix pitch to form a stitched braided sleeve; S4: heating and heat-insulating the stitched braided sleeve to form a braided sleeve preform of bone screw structure; S5: placing the preform into a cavity mold of bone screw structure, injecting, cooling, demolding, heat treating and cooling of short-cut carbon fiber reinforced polyaryletherketone raw material to obtain a carbon fiber composite bone screw.

2. The method for preparing carbon fiber composite bone screws according to claim 1, characterized in that: The shape memory alloy is a nickel-titanium-based memory alloy, and the shape memory alloy profile is one of wire, sheet or tube; The wire diameter of the wire is 0.1-0.3 mm; The width and thickness of the sheet are 0.1-0.3 mm; The outer tube diameter of the tube is 0.3 mm and the tube thickness is 0.1 mm; In step S1, a mark is made on the shape memory alloy profile before straightening, which is tangent to the inner surface of the cylindrical profile formed by the helix, and the mark is still tangent to the inner surface of the cylindrical profile formed by the shape memory alloy profile after stitching in step S3.

3. The method for preparing carbon fiber composite bone screws according to claim 2, characterized in that: In the nickel-titanium-based memory alloy, the mass fraction of nickel is 54.5%-57.0%, and the mass fraction of impurity elements is required to be carbon ≤0.040%, cobalt ≤0.050%, copper ≤0.010%, chromium ≤0.010%, hydrogen ≤0.005%, iron ≤0.050%, niobium ≤0.025%, nitrogen ≤0.005%, oxygen ≤0.040%, and the balance is titanium, the martensitic transformation completion temperature of the nickel-titanium-based memory alloy is 10-20℃, and the austenitic transformation completion temperature is 40-50℃.

4. The method for preparing carbon fiber composite bone screws according to claim 1, characterized in that: The hot coiling forming in step S1 comprises heating the shape memory alloy profile to 400-500℃, and then placing it into a roller device to perform hot coiling forming at a winding speed of 2-10 mm / s, a winding force of 1-10 N and a winding diameter of 3.0-8.0 mm; The cooling condition is natural air cooling to room temperature and then forced cooling to complete martensitic transformation; The temperature of the shape memory alloy profile is kept at the temperature after cooling before the stitching in step S3 is completed.

5. The method for preparing carbon fiber composite bone screws according to claim 4, characterized in that: In step S2, the wire diameter of the carbon fiber is 5-10 μm, the carbon fiber is twisted or partially twisted, and the braided sleeve adopts 2D braiding or 3D braiding; The organization structure of the 2D braiding is a 2D three-axis braided sleeve with a specification of 2×2, 1×1, 3×3 or 2×1; the braiding yarn and the axial yarn are both carbon fibers, the braiding yarn width is 0.5 mm when at rest, the braiding angle is 30-60°, the spool is 64, the axial yarn is 32, the cover factor is ≥90%, and the braiding pitch is 5-8 mm; The 3D braided sleeve adopts a four-step method to perform one of three-dimensional four-way, three-dimensional five-way, three-dimensional six-way and three-dimensional seven-way braiding methods, the braiding angle ranges from 10° to 45°, the stitch length is 0.5-11.5 mm, and the stitch width is 0.5-2.0 mm. Step S2 further includes drying the braided sleeve to a moisture content of less than 0.1% by mass, and then cooling it to below the martensitic transformation temperature of the shape memory alloy profile. The braided sleeve is kept at this cooled temperature until the stitching is completed in step S3.

6. The method for preparing carbon fiber composite bone screws according to claim 4, characterized in that: After completing step S4 and before proceeding to step S5, the process further includes placing a continuous carbon fiber-polyetheretherketone (PEEK) core into the sewn braided sleeve. The PEEK melt index of the continuous carbon fiber-PEEK core is 76 g / 10 min under the conditions of 380°C and 5 kg load. The continuous carbon fiber-polyetheretherketone (PEEK) core has a fiber volume content of 60%. Based on the fiber orientation direction, the continuous carbon fiber-PEEK core has a tensile strength ≥2000MPa, a compressive strength ≥1250MPa, and a short beam shear strength ≥90MPa.

7. The method for preparing carbon fiber composite bone screws according to claim 4, characterized in that: The stitching includes single-helix stitching and double-helix stitching; The single spiral stitching includes spirally stitching a first shape memory alloy profile along the axial direction at intervals of 1.5-5.0 mm to the surface of the carbon fiber braided sleeve, and alternately stitching a second shape memory alloy profile with the same intervals to the first shape memory alloy profile; The double helix stitching includes alternately spirally stitching the first and second shape memory alloy profiles along the axial direction at a spacing of 1.5-5.0 mm to the surface of the carbon fiber braided sleeve, and alternately stitching the third and fourth shape memory alloy profiles with the first and second shape memory alloy profiles at the same spacing. The stitching to the surface of the carbon fiber braided sleeve includes stitching around the outer surface, the inner surface, or both the outer and inner surfaces, with the winding direction being clockwise or counterclockwise.

8. The method for preparing carbon fiber composite bone screws according to claim 1, characterized in that: The heating and heat preservation step S4 includes: heating the woven sleeve to a temperature of 100-150℃ and then keeping it at that temperature for 5-15 minutes, wherein the heating rate does not exceed 10℃ / min.

9. The method for preparing carbon fiber composite bone screws according to claim 8, characterized in that: The short-cut carbon fiber reinforced polyaryletherketone resin mentioned in step S5 is selected from one of short-cut carbon fiber reinforced polyetheretherketone and short-cut carbon fiber reinforced polyetherketone ketone, wherein the fiber mass content in the short-cut carbon fiber reinforced polyaryletherketone resin is 30%±2%; Injection molding temperature: 360℃-400℃, hot runner temperature control system temperature: 350℃-380℃, mold temperature: 150-200℃, injection pressure: 80-200MPa, injection rate: 50-400mm / s; The heat treatment temperature is 170-250℃, the duration is 2-12h, the cooling rate is 0.2-2℃ / min, the temperature after cooling is 120-160℃, and then it is naturally cooled to room temperature.

10. A carbon fiber composite bone screw, characterized by: The bone screw is prepared using the carbon fiber composite material bone screw preparation method as described in any one of claims 1-9, comprising: a structural reinforcement skeleton and a structural matrix; The structure reinforcing framework is a stitch-braided sleeve, the stitch-braided sleeve is made of shape memory alloy profiles which are equidistantly stitched on the surface of the braided sleeve along the axial direction and matched with the screw pitch to form the stitch interval; the braided sleeve is made of carbon fiber braiding. The structure base is a short-cut carbon fiber reinforced polyaryletherketone.

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