Outer tube structure, preparation method thereof and OCT (optical coherence tomography) imaging catheter

Abstract

The invention relates to the technical field of medical instruments, and discloses an outer tube structure, a preparation method thereof and an OCT imaging catheter, and the preparation method comprises the following steps: preparing a near-end tube and a far-end tube; the far end of the near-end pipe is machined to form a first step, and the near end of the far-end pipe is machined to form a second step matched with the first step in size; performing laser cladding on the first step and the second step to form a laser molten pool of the first step and the second step; and axial vibration and radial stamping are applied to the laser molten pool, so that the first step and the second step are welded into a whole. Therefore, the smoothness of the splicing position can be improved, the connection reliability of the splicing position can be improved, the problem that the smoothness of the splicing position and the connection reliability are contradictory is solved, damage to intracranial blood vessels in the outer tube pushing process is avoided, and the splicing position is also prevented from being broken or falling off in the outer tube pushing process.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an outer tube structure and its preparation method, and an OCT imaging catheter. Background Technology

[0002] Optical coherence tomography (OCT) is a novel biomedical imaging method based on weak coherence optical tomography technology. It can perform in vivo tomographic imaging of biological tissues. With its high-resolution imaging characteristics, OCT imaging technology can clearly and completely present the details of the internal structure of blood vessels. It has now become the mainstream vascular imaging method. Currently, OCT imaging catheters are widely used in coronary arteries and intracranial blood vessels.

[0003] In clinical applications, the distal end of the OCT imaging catheter is pushed into the blood vessel, while the proximal end is connected to the COT host. The imaging probe inside the OCT imaging catheter is driven to rotate and move axially within the catheter. During imaging, the imaging probe is first moved through the lesion location within the blood vessel and reaches the distal end of the lesion location. Then, the imaging probe is rotated back to complete a 360° scan of a segment of the blood vessel, forming a spatial image of this segment of the blood vessel.

[0004] To improve the efficiency of distal delivery of OCT imaging catheters and avoid damage to blood vessels, the outer cannula of OCT imaging catheters is typically designed in segments, consisting of a proximal and a distal portion. The proximal portion is usually made of a high-hardness material to improve thrust transmission, while the distal portion is typically made of a low-hardness material to accommodate vascular curvature and reduce the risk of injury. However, in conventional techniques, the proximal and distal portions of the outer cannula are usually glued or thermofused together, which can easily lead to uneven surfaces or local protrusions at the joint, resulting in insufficient overall smoothness of the outer cannula. In the fragile intracranial vascular environment, uneven surfaces or local protrusions pose a risk of damaging the vascular wall. Furthermore, glued or thermofused connections are prone to instability, leading to the risk of breakage or detachment at the joint, thus causing clinical safety hazards. In addition, if uneven surfaces or local protrusions are trimmed to improve the smoothness of the joint, the bonding or welding area will be reduced, thus creating a trade-off between the smoothness of the outer cannula joint and the connection strength. Summary of the Invention

[0005] In view of this, the present invention provides an outer tube structure and its preparation method and an OCT imaging catheter to solve the problems of conventional OCT imaging catheters with segmented outer tube design, insufficient smoothness and unreliable connection at the splicing points of the outer tube, which can easily damage the inner wall of blood vessels and even cause clinical safety hazards. In addition, there is a contradiction between the smoothness and connection strength at the splicing points of the outer tube.

[0006] In a first aspect, the present invention provides a method for preparing an outer tube structure, comprising:

[0007] Preparation of proximal and distal tubes;

[0008] The distal end of the proximal tube is machined to form a first step, and the proximal end of the distal tube is machined to form a second step that matches the size of the first step.

[0009] Laser cladding is performed on the first step and the second step to form laser molten pools for the first step and the second step;

[0010] Axial vibration and radial stamping are applied to the laser molten pool to weld the first step and the second step together.

[0011] Optionally, the laser cladding of the first and second steps to form a first laser molten pool and a second laser molten pool respectively specifically includes: using a wavelength of 1070nm, a power range of 180W to 220W, and a power of 70-90J / mm². 3 Low-energy-density lasers are used to perform laser cladding on the first and second steps.

[0012] Optionally, a checkerboard scanning strategy can be used to perform laser cladding on the first and second steps.

[0013] Optionally, applying axial vibration and radial stamping to the laser molten pool specifically includes: applying ultrasonic vibration to the laser molten pool in the axial direction, wherein the vibration frequency range of the ultrasonic vibration is 33.25 kHz to 36.75 kHz; and applying high-frequency micro-stamping to the laser molten pool in the radial direction, wherein the pressure range of the high-frequency micro-stamping is 50 MPa to 100 MPa, and the stamping frequency of the high-frequency micro-stamping is 700 times / second to 1000 times / second.

[0014] Optionally, after welding the first step and the second step together, the method further includes:

[0015] The first and second steps after welding are subjected to an annealing process, wherein the annealing process includes: heating to 350°C at 10°C / min and holding at that temperature for 2 hours, followed by slow cooling at 5°C / min.

[0016] And / or, the annealing process is a gradient annealing process.

[0017] Optionally, a first step is formed at the distal end of the proximal tube, and a second step is formed at the proximal end of the distal tube to match the size of the first step, specifically including:

[0018] The outer wall of the near-end tube is machined to form a first step, and the inner wall of the far-end tube is machined to form a second step that matches the size of the first step.

[0019] Optionally, the outer surface of the distal end of the proximal tube is mechanically stripped away at half the wall thickness to form the first step, and the inner surface of the proximal end of the inner wall of the distal tube is mechanically stripped away at half the wall thickness to form the second step.

[0020] And / or, the overlap dimension of the first step and the second step in the axial direction ranges from 6 mm to 7 mm.

[0021] Secondly, the present invention provides an outer tube structure, which is prepared by the above-described method for preparing an outer tube structure, the outer tube structure comprising:

[0022] The proximal end of the tube has a first step formed at the distal end;

[0023] The distal end of the tube has a second step formed at the proximal end, the second step being adapted to the size of the first step, and the first and second steps being suitable for insertion and mating.

[0024] Optionally, the proximal tube includes an inner layer, a middle layer, and an outer layer arranged sequentially from the inside to the outside; the inner layer is made of polytetrafluoroethylene, the middle layer is made of stainless steel braided wire, and the outer layer is made of polyimide; the distal tube is made of polyether block polyamide.

[0025] And / or, the outer wall of the distal end of the proximal tube is provided with a hydrophilic coating, and the outer wall of the distal tube is provided with a hydrophilic coating.

[0026] Thirdly, the present invention provides an OCT imaging catheter, including the aforementioned outer tube structure.

[0027] Beneficial effects:

[0028] 1. The method for preparing the outer tube structure provided by the present invention includes:

[0029] Preparation of proximal and distal tubes;

[0030] The distal end of the proximal tube is machined to form a first step, and the proximal end of the distal tube is machined to form a second step that matches the size of the first step.

[0031] Laser cladding is performed on the first step and the second step to form laser molten pools for the first step and the second step;

[0032] Axial vibration and radial stamping are applied to the laser molten pool to weld the first step and the second step together.

[0033] Through the above preparation method, the first and second steps can increase the contact area at the joint of the near-end and far-end tubes, thereby increasing the formation area of ​​the laser molten pool and improving the connection strength. Furthermore, the interlocking of the first and second steps avoids the welded part being exposed on the outer wall of the joint, preventing the formation of uneven surfaces or protrusions, thus improving the smoothness of the outer tube. Further, during the welding process, axial vibration and radial pressure are applied to the laser molten pool. Axial vibration generates periodic pressure fluctuations in the laser molten pool, inducing cavitation to break dendrites and drive element diffusion. Radial pressure causes plastic deformation of the semi-solid metal, closing pores and microcracks. Axial vibration and radial pressure refine the grain size, increase the proportion of equiaxed grains, and reduce residual porosity, thereby improving tensile strength and further smoothing the outer wall of the joint between the near-end and far-end tubes, improving smoothness.

[0034] Therefore, the outer tube structure prepared by the above method can improve both the smoothness of the splice and the reliability of the connection at the splice, overcoming the contradiction between the smoothness of the splice and the reliability of the connection, avoiding damage to intracranial blood vessels during the outer tube push process, and also avoiding breakage or detachment at the splice during the outer tube push process.

[0035] 2. The method for fabricating the outer tube structure provided by the present invention, wherein laser cladding is performed on the first step and the second step to form laser molten pools for the first step and the second step respectively, specifically includes: using a wavelength of 1070nm, a power range of 180W to 220W, and 70-90J / mm². 3 A low-energy-density laser is used to perform laser cladding on the first and second steps. This setup allows for precise control of the molten pool area, making it suitable for fine-grained laser cladding of the first and second steps. It also reduces energy density, lowers the peak temperature of the molten pool, suppresses liquid metal splashing, and improves the stability of the first and second laser molten pools, facilitating subsequent interlocking steps.

[0036] 3. The method for fabricating the outer tube structure provided by this invention employs a checkerboard scanning strategy to perform laser cladding on the first and second steps. This configuration decomposes the laser cladding areas on the first and second steps into multiple small units, avoiding excessive overall temperature rise and reducing stress concentration, thus reducing the risk of cracking.

[0037] 4. The method for preparing the outer tube structure provided by the present invention, wherein applying axial vibration and radial stamping to the laser molten pool specifically includes: applying ultrasonic vibration to the laser molten pool in the axial direction, wherein the vibration frequency range of the ultrasonic vibration is 33.25 kHz to 36.75 kHz; and applying high-frequency micro-stamping to the laser molten pool in the radial direction, wherein the pressure range of the high-frequency micro-stamping is 50 MPa to 100 MPa, and the stamping frequency of the high-frequency micro-stamping is 700 times / second to 1000 times / second. Since the radius of cavitation bubbles is inversely proportional to the vibration frequency, if the vibration frequency is too low, the cavitation bubble size will be too large, easily leading to violent fluctuations in the laser molten pool; if the vibration frequency is too high, the number of cavitation bubbles will be too large, the radius will be small, and the energy density will be insufficient, resulting in a decrease in breaking efficiency. Therefore, ultrasonic vibration within the above vibration frequency range can ensure that the generated cavitation bubbles are in the optimal state for breaking dendrites, which can both efficiently break dendrites and avoid violent fluctuations in the laser molten pool. Since the first and second laser molten pools are in the metastable range of molten metal solidification, radial stamping within the aforementioned pressure range and stamping frequency range can induce plastic flow of the metastable metal, promote dynamic recrystallization of grains, effectively reduce residual porosity, and improve tensile strength.

[0038] 5. The method for preparing the outer tube structure provided by the present invention, after welding the first step and the second step together, further includes: annealing the welded first step and the second step, wherein the annealing process includes: heating to 350°C at 10°C / min and holding at that temperature for 2 hours, followed by slow cooling at 5°C / min; and / or, the annealing process is a gradient annealing process. This configuration, by annealing the welded first step and the second step, can release stress, ensure the geometric stability and structural integrity of the joint, and prevent breakage at the joint due to stress concentration during use. The above-mentioned annealing process can rearrange atoms and release stress. Residual stress is reduced by more than 80%, ensuring the geometric stability and structural integrity of the joint. It also prevents the outer tube from breaking due to stress concentration when pushed into the blood vessel, improving operational safety.

[0039] 6. The method for preparing the outer tube structure provided by the present invention involves processing the distal end of the proximal tube to form a first step, and processing the proximal end of the distal tube to form a second step that matches the size of the first step. Specifically, it includes: processing the distal end of the outer wall of the proximal tube to form a first step, and processing the proximal end of the inner wall of the distal tube to form a second step that matches the size of the first step. Since the proximal tube is usually made of multilayer composite materials, the first step processed at the distal end of the outer wall of the proximal tube can ensure mechanical strength, and the matching of the second step with the first step can avoid uneven surfaces or protrusions at the joint.

[0040] 7. The method for preparing the outer tube structure provided by the present invention involves mechanically removing half the wall thickness from the distal outer surface of the proximal tube to form the first step, and mechanically removing half the wall thickness from the proximal inner surface of the distal tube to form the second step. This arrangement ensures the mechanical strength of the first and second steps.

[0041] The overlap between the first step and the second step in the axial direction ranges from 6 mm to 7 mm, thereby increasing the splicing area of ​​the first step and the second step and improving the tensile strength.

[0042] 8. The outer tube structure provided by the present invention is prepared by the above-described method for preparing the outer tube structure. The outer tube structure includes a proximal tube and a distal tube.

[0043] The proximal end of the proximal tube has a first step. The proximal end of the distal tube has a second step, the size of which is adapted to the first step. The first and second steps are suitable for insertion and mating. This design avoids the formation of uneven surfaces or protrusions at the joint of the proximal and distal tubes. Furthermore, the above method improves both the smoothness and reliability of the joint, overcoming the contradiction between smoothness and reliability. This also prevents damage to intracranial blood vessels during external tube delivery and avoids breakage or detachment at the joint during delivery.

[0044] 9. The outer tube structure provided by this invention includes an inner layer, a middle layer, and an outer layer arranged sequentially from the inside to the outside. The inner layer is made of polytetrafluoroethylene (PTFE), which has high lubricity and corrosion resistance, facilitating the movement of the imaging probe within the outer tube and preventing reaction with contrast agents. The middle layer is made of stainless steel braided wire, improving the mechanical strength of the proximal tube. The outer layer is made of polyimide, giving the proximal tube good biocompatibility and reducing rejection reactions. The distal tube is made of polyether block polyamide, which has good elasticity, wear resistance, and fatigue resistance, adapting to intracranial vascular deformation and exhibiting good biocompatibility, reducing rejection reactions.

[0045] The outer wall of the proximal tube is coated with a hydrophilic coating. Since blood is composed of plasma and blood cells, with plasma accounting for approximately 55% and water accounting for 90%, the hydrophilic coating reduces the friction between the outer tube and the blood during the pushing process, greatly enhancing the pushability of the outer tube. Attached Figure Description

[0046] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0047] Figure 1 This is a flowchart illustrating the preparation method of the outer tube structure according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the composition principle of an SLM metal printer according to an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of the structure of the OCT imaging catheter according to an embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of the joint between the proximal and distal tubes in an embodiment of the present invention.

[0051] Figure 5 This is a schematic cross-sectional view of the proximal tube according to an embodiment of the present invention;

[0052] Figure 6 for Figure 3 Enlarged view of point A in the middle;

[0053] Figure 7 for Figure 3 Enlarged view of point B in the middle.

[0054] Explanation of reference numerals in the attached figures:

[0055] 1. Outer tube structure; 101. Inner layer; 102. Middle layer; 103. Outer layer; 11. Proximal tube; 111. First step; 12. Distal tube; 121. Second step; 13. Shaft marking strip; 14. Imaging window; 201. Welding platform; 202. Fiber laser; 203. Laser beam; 204. Ultrasonic generator; 205. Forging head; 206. Piezoelectric ceramic transducer; 2. Guide wire head; 211. Welding area; 3. Imaging structure; 31. Torque transmission tube; 32. Imaging probe; 33. First developing ring; 34. Second developing ring; 4. Connecting seat; 5. Stress buffer tube; 6. Protective sleeve; 7. Protective cover. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] It should be noted that in this application, the end closer to the operator during use is referred to as the "proximal end," and the end farther from the operator is referred to as the "distal end." Based on this principle, the "proximal end" and "distal end" of any component of the OCT imaging catheter are defined. "Axial direction" generally refers to the length direction of the OCT imaging catheter during delivery, and "radial direction" generally refers to the direction of the OCT imaging catheter perpendicular to its "axial direction." Based on this principle, the "axial direction" and "radial direction" of any component of the OCT imaging catheter are defined.

[0058] like Figure 1 and Figure 3 As shown, Figure 1 A flowchart illustrating the fabrication method of the outer tube structure is shown. Figure 3 A schematic diagram of the outer tube structure 1 is shown, specifically illustrating the structural diagram of the joint between the proximal tube 11 and the distal tube 12. This embodiment provides a method for fabricating the outer tube structure, including:

[0059] Step S100: Prepare the proximal tube 11 and the distal tube 12;

[0060] Specifically, the outer tube structure, as a component of the OCT imaging catheter, is used to push into the blood vessel. The outer tube structure adopts a segmented design, with the proximal tube 11 as the proximal part of the outer tube structure and the distal tube 12 as the distal part of the outer tube structure.

[0061] In one specific embodiment, the proximal tube 11 includes an inner layer, a middle layer, and an outer layer arranged sequentially from the inside out. The inner layer is made of polytetrafluoroethylene (PTFE), which has high lubricity and corrosion resistance, facilitating the movement of the imaging probe in the outer tube and preventing reaction with the contrast agent. The middle layer is made of stainless steel braided wire, which improves the mechanical strength of the proximal tube 11. For example, 304 stainless steel braided wire can be used, with the wire specifications being 0.075*0.13mm flat wire and a braiding density of 115PPI to 125PPI, using a one-over-two braiding method. The outer layer is made of polyimide, giving the proximal tube 11 good biocompatibility and reducing rejection reactions. The distal tube 12 is made of polyether block polyamide, which has good elasticity, wear resistance, and fatigue resistance, adapting to intracranial vascular deformation and exhibiting good biocompatibility, reducing rejection reactions. The proximal tube 11 is made to be harder than the distal tube 12, so that the proximal tube 11 can improve the pushing efficiency, and the distal tube 12 can improve the ability to adapt to the tortuous shape of intracranial blood vessels, thereby protecting the blood vessels.

[0062] In one specific embodiment, the wall thickness of the proximal tube 11 and the distal tube 12 is 0.06 mm, wherein the inner layer thickness of the proximal tube 11 is 0.015 mm, the middle layer thickness is 0.015 mm, and the outer layer thickness is 0.03 mm.

[0063] In step S200, the distal end of the proximal tube 11 is machined to form a first step 111, and the proximal end of the distal tube 12 is machined to form a second step 121 that matches the size of the first step 111.

[0064] Specifically, the first step 111 refers to the step-like structure formed by mechanical peeling of the proximal tube 11. The first step 111 includes an arcuate surface extending axially and an annular surface extending radially. The annular surface is located away from the distal tip of the proximal tube 11. The arcuate surface connects the arcuate surface and the tip of the proximal tube 11. Similarly, the second step 121 is adapted to the shape and size of the first step 111 so as to facilitate the insertion and mating of the first step 111 and the second step 121.

[0065] In one specific embodiment, the distal end of the proximal tube 11 is machined to form a first step 111, and the proximal end of the distal tube 12 is machined to form a second step 121 that matches the size of the first step 111. Specifically, this includes: machining the distal end of the outer wall of the proximal tube 11 to form the first step 111, and machining the proximal end of the inner wall of the distal tube 12 to form a second step 121 that matches the size of the first step 111. Since the proximal tube 11 is typically made of multi-layer composite material, the first step 111 machined at the distal end of the outer wall of the proximal tube 11 ensures mechanical strength, and the matching of the second step 121 with the first step 111 avoids uneven surfaces or protrusions at the joint. Following the previous example, the first step 111 is formed by processing the far end of the outer wall of the proximal tube 11, which can retain the middle layer and the inner layer, thereby ensuring the mechanical strength of the far end of the proximal tube 11. The second step 121 is formed by processing the near end of the inner wall of the far end tube 12. After splicing, the splice will include at least three layers of material, namely, the inner layer is polytetrafluoroethylene material, the middle layer is stainless steel braided wire, and the outer layer is polyether block polyamide material, thereby improving the mechanical strength and bending flexibility of the splice.

[0066] In one specific embodiment, the distal outer surface of the outer wall of the proximal tube 11 is mechanically peeled away by half its wall thickness to form the first step 111, and the proximal inner surface of the inner wall of the distal tube 12 is mechanically peeled away by half its wall thickness to form the second step 121. Since the wall thickness of the proximal tube 11 is 0.06 mm, the outer wall thickness of the proximal tube 11 is 0.03 mm, and the wall thickness of the distal tube 12 is 0.06 mm, the mechanical peeling as described above allows the first step 111 to have an intermediate layer and an inner layer, and the second step 121 is adapted to the size and shape of the first step 111, thereby improving the smoothness of the joint, as well as the mechanical strength and flexibility of the bending action at the joint.

[0067] In one alternative embodiment, the overlap dimension of the first step 111 and the second step 121 in the axial direction ranges from 6 mm to 7 mm, thereby increasing the splicing area of ​​the first step 111 and the second step 121 and improving the tensile strength.

[0068] Based on this, the pretreatment of the proximal tube 11 and the distal tube 12 before welding can be completed through the above steps, so as to facilitate the subsequent welding of the proximal tube 11 and the distal tube 12. The welding method is as follows:

[0069] Step S300: Laser cladding is performed on the first step 111 and the second step 121 to form a laser molten pool of the first step and the second step.

[0070] Specifically, laser cladding refers to using a fiber laser to fuse cladding material onto the surfaces of the first step 111 and the second step 121, causing partial surface layers of the first step 111 and the second step 121 to fuse with the cladding material, thereby forming laser molten pools on the first and second steps. The laser cladding process can be completed using an SLM metal printer, and the cladding material can be selected from 316L stainless steel powder with a particle size range of 15μm to 45μm.

[0071] In one specific embodiment, the laser cladding of the first step 111 and the second step 121 to form a laser molten pool for the first step and the second step specifically includes: using a wavelength of 1070nm, a power range of 180W to 220W, and a laser strength of 70-90J / mm². 3 The first step 111 and the second step 121 are laser claddinged with a low energy density laser.

[0072] A laser wavelength of 1070nm can improve the absorption rate of 316L stainless steel powder to the laser, effectively converting light energy into heat energy. This allows the 316L stainless steel powder to melt rapidly on the surfaces of the first step 111 and the second step 121. The laser power range can be adjusted between 180W and 220W according to the particle size of the 316L stainless steel powder; that is, the laser power increases with the increase of the particle size of the 316L stainless steel powder to ensure the melting of the stainless steel powder and the stability of the laser-melted pool. (70J / mm) 3 Up to 90J / mm 3 The low-energy-density laser can reduce energy density, lower the peak temperature of the molten pool, suppress liquid metal splashing, and improve the stability of the first and second laser molten pools, thus facilitating subsequent insertion steps.

[0073] In addition, preset parameters may include a spot diameter of 70μm and a thickness of 25μm, which can ensure precise control of the molten pool range, reduce energy accumulation, and avoid excessive melting of the first step 111 and the second step 121.

[0074] In one specific implementation, a checkerboard scanning strategy is used to perform laser cladding on the first step 111 and the second step 121. The checkerboard scanning strategy involves dividing the area to be clad into multiple small units and scanning each unit sequentially. For example, a horizontal scan can be performed first, followed by a vertical scan, and this process can be repeated. This disperses thermal stress along different directions, reducing unidirectional stress concentration. Furthermore, a 30% scan overlap rate can be set to reduce cooling efficiency and the risk of cracking. Therefore, the laser cladding area on the first step 111 and the second step 121 can be decomposed into multiple small units, avoiding excessive overall temperature rise, reducing stress concentration, reducing the risk of cracking, and further improving the stability of the laser molten pool.

[0075] In the laser cladding process described above, the state of the molten pool can be monitored in real time by the vision system of the SLM metal printer. The detection scanning speed ranges from 500 mm / s to 700 mm / s, thereby reducing the errors in the laser cladding process and subsequent axial vibration and radial stamping processes, and avoiding vibration interference that could cause the molten pool to shift.

[0076] In step S400, axial vibration and radial stamping are applied to the laser molten pool to weld the first step 111 and the second step 121 together.

[0077] Specifically, axial vibration refers to applying axial vibration to the laser molten pool through the forging head, while radial stamping refers to applying radial stamping to the laser molten pool through the forging head after applying axial vibration for a predetermined time. In this embodiment, the ultrasonic generator, piezoelectric ceramic transducer, and forging head can be integrated into the SLM metal printer, and all of the above structures are uniformly controlled by the PLC controller of the SLM metal printer, for example... Figure 2 As shown, the SLM metal printer includes a welding platform 201, a fiber laser 202, an ultrasonic generator 204, a forging head 205, and a piezoelectric ceramic transducer 206. The ultrasonic generator 204 is linked with the forging head 205 through the piezoelectric ceramic transducer 206, thereby applying axial vibration and radial stamping to the first step 111 and the second step 121 through the forging head 205.

[0078] In one specific embodiment, applying axial vibration and radial pressure to the first step 111 and the second step 121 specifically includes:

[0079] Ultrasonic vibration is applied to the laser molten pool in the axial direction, and the vibration frequency of the ultrasonic vibration is in the range of 33.25 kHz to 36.75 kHz.

[0080] Since the radius of cavitation bubbles is inversely proportional to the vibration frequency, if the vibration frequency is too low, the cavitation bubble size will be too large, easily leading to violent fluctuations in the laser molten pool. If the vibration frequency is too high, the number of cavitation bubbles will be too large, the radius will be too small, and the energy density will be insufficient, resulting in a decrease in breakup efficiency. Therefore, ultrasonic vibration within the above-mentioned frequency range can ensure that the generated cavitation bubbles are in the optimal state for dendrite breakup, which can efficiently break dendrites while avoiding violent fluctuations in the laser molten pool. Experiments have verified that the grain size range of the laser molten pool is 50μm to 100μm. When the vibration frequency range is 33.25kHz to 36.75kHz, the cavitation effect can refine the grain size range to 5μm to 15μm, increasing the proportion of equiaxed crystals to over 80%. Preferably, the vibration frequency is 35kHz.

[0081] High-frequency micro-impact is applied to the laser molten pool in the radial direction. The pressure range of the high-frequency micro-impact is 50MPa to 100MPa, and the impact frequency of the high-frequency micro-impact is 700 times / second to 1000 times / second.

[0082] Because the laser-treated molten pool is located in the metastable state of molten metal solidification, with a temperature range of 800℃ to 1200℃, radial stamping within the aforementioned pressure and frequency range can induce plastic flow in the metastable metal, promoting dynamic recrystallization of grains, effectively reducing residual porosity, and increasing tensile strength. Experiments have verified that radial stamping can reduce porosity to 0.3%, resulting in a tensile strength of 370 MPa to 400 MPa at the joint.

[0083] In one embodiment of this invention, before applying axial vibration and radial stamping to the laser molten pool, the method further includes: inserting and engaging the first step 111 and the second step 121 after laser cladding, wherein the laser molten pools of the first step and the second step are in contact with each other.

[0084] Specifically, the proximal tube 11 and the outer tube 12 can be mounted on a forging head during welding, and the insertion of the first step 111 and the second step 121 can be completed quickly through the forging head, so as to facilitate the subsequent application of axial vibration and radial stamping to the laser molten pool.

[0085] In one embodiment of this invention, after welding the first step and the second step together, the process further includes annealing the welded first step 111 and second step 121. Annealing the welded first step and second step can release stress, ensure the geometric stability and structural integrity of the joint, and prevent the joint from breaking due to stress concentration during use.

[0086] In one specific embodiment, the annealing process includes: heating to 350°C at a rate of 10°C / min and holding at that temperature for 2 hours, followed by slow cooling at a rate of 5°C / min; and / or, the annealing process is a gradient annealing process. This configuration allows atoms to rearrange and release stress. Residual stress is reduced by more than 80%, ensuring the geometric stability and structural integrity of the splice joint. It also prevents the outer tube from breaking due to stress concentration during intravascular insertion, improving operational safety.

[0087] Through the above preparation method, the first step 111 and the second step 121 can increase the contact area at the joint of the proximal tube 11 and the distal tube 12, thereby increasing the formation area of ​​the laser molten pool and improving the connection strength. Moreover, the interlocking of the first step 111 and the second step 121 can avoid the welded part being exposed on the outer wall of the joint, thus avoiding the formation of uneven surfaces or protrusions on the outer wall of the joint, thereby improving the smoothness of the outer tube. Furthermore, during the welding process, axial vibration and radial stamping are applied to the first step 111 and the second step 121. Axial vibration can generate periodic pressure fluctuations in the laser molten pool, triggering cavitation effects to break dendrites and drive element diffusion. Radial stamping can cause plastic deformation of the semi-solid metal, closing pores and microcracks. Through axial vibration and radial stamping, the grain size can be refined, the proportion of equiaxed grains can be increased, and the residual porosity can be reduced, thereby improving the tensile strength. It can also further smooth the outer wall of the joint of the proximal tube 11 and the distal tube 12, improving the smoothness. Furthermore, the first step 111 and the second step 121 after welding are annealed to release stress, ensure the geometric stability and structural integrity of the joint, and avoid the joint from breaking due to stress concentration during use.

[0088] Therefore, the outer tube structure prepared by the above method can improve both the smoothness of the splice and the reliability of the connection at the splice, overcoming the contradiction between the smoothness of the splice and the reliability of the connection, avoiding damage to intracranial blood vessels during the outer tube push process, and also avoiding breakage or detachment of the splice of the outer tube during the outer tube push process.

[0089] like Figure 3 and Figure 4 As shown, this embodiment provides an outer tube structure, which is prepared by the above-described method. The outer tube structure 1 includes a proximal tube 11 and a distal tube 12.

[0090] The proximal end of the proximal tube 11 has a first step 111. The proximal end of the distal tube 12 has a second step 121, the second step 121 being sized to match the first step 111. The first step 111 and the second step 121 are suitable for insertion and mating. This arrangement avoids the formation of uneven surfaces or protrusions at the joint between the proximal tube 11 and the distal tube 12. Furthermore, the above method improves both the smoothness and reliability of the joint, overcoming the contradiction between smoothness and reliability. This also prevents damage to intracranial blood vessels during external tube delivery and avoids breakage or detachment at the joint during external tube delivery.

[0091] like Figure 4As shown, in one embodiment of this example, a first step 111 is formed on the distal end of the outer wall of the proximal tube 11, and a second step 121 is formed on the proximal end of the inner wall of the distal tube. The overlap area S1 of the first step 111 and the second step 121 is 6 mm to 7 mm. The outer diameter and inner diameter of the proximal tube 11 and the distal tube 12 are consistent. The outer diameter of the proximal tube 11 and the distal tube 12 can be 0.48 mm, and the inner diameter can be 0.36 mm. The wall thickness of the proximal tube 11 and the distal tube 12 can be 0.06 mm. During processing, half of the wall thickness is peeled off at the distal end of the outer wall of the proximal tube 11, with a peeling length of 6 mm to 7 mm in the axial direction. Half of the wall thickness is peeled off at the proximal end of the inner wall of the distal tube 12, with a peeling length of 6 mm to 7 mm in the axial direction. The peeling lengths of the proximal tube 11 and the distal tube 12 are consistent.

[0092] like Figure 5 As shown, in one embodiment of this invention, the proximal tube 11 includes an inner layer 101, a middle layer 102, and an outer layer 103 arranged sequentially from the inside to the outside. The inner layer 101 is made of polytetrafluoroethylene (PTFE), which has high lubricity and corrosion resistance, facilitating the movement of the imaging probe in the outer tube and preventing reaction with the contrast agent. The middle layer 102 is made of stainless steel braided wire, improving the mechanical strength of the proximal tube. The outer layer 103 is made of polyimide, giving the proximal tube good biocompatibility and reducing rejection reactions. The distal tube is made of polyether block polyamide, which has good elasticity, wear resistance, and fatigue resistance, adapting to intracranial vascular deformation and exhibiting good biocompatibility, reducing rejection reactions.

[0093] like Figure 5 As shown, in one embodiment of this example, the wall thickness of the inner layer 101 can be 0.015 mm, the wall thickness of the middle layer 102 can be 0.015 mm, and the wall thickness of the outer layer can be 0.03 mm. Peeling the distal end of the outer wall of the proximal tube 11 means peeling off the outer layer of the distal end of the outer wall of the proximal tube 11, exposing the middle layer 102.

[0094] In one embodiment of this invention, the outer wall of the distal end of the proximal tube 11 is provided with a hydrophilic coating, and the outer wall of the distal tube 12 is also provided with a hydrophilic coating. The hydrophilic coating can be applied by dipping in a hyaluronic acid-based solution followed by thermosetting. Since blood is composed of plasma and blood cells, with plasma comprising approximately 55% and water comprising 90%, the hydrophilic coating can reduce the friction between the outer tube and the blood during dispensing, greatly enhancing the dispensability of the outer tube. Alternatively, the outer wall of the proximal tube 11 is provided with a hydrophilic coating.

[0095] like Figure 3 and Figure 6As shown, in this embodiment, an OCT imaging catheter is provided, including the outer tube structure 1 described above, and also including a guidewire head 2, an imaging structure 3, a connector 4, a stress buffer tube 5, a protective sleeve 6, and a protective cap 7.

[0096] The guide wire 2 is connected to the distal end of the outer tube structure 1. The guide wire 2 is used to guide the outer tube structure 1 to move towards the lesion location. The guide wire 2 can be welded to the distal end of the outer tube structure 1 through the welding area 211.

[0097] The connecting seat 4 is connected to the proximal end of the outer tube structure through the stress buffer tube 5. The connecting seat 4 is used to connect to the OCT host. Since the outer tube structure 1 will bend and deform during the pushing process, the stress buffer tube 5 can make the stress be transmitted and dissipated more smoothly to the proximal end, avoiding the outer tube structure from breaking due to stress concentration.

[0098] Imaging structure 3 extends from the proximal end of connector 4 into outer tube structure 1 and is driven to move along the axial direction of outer tube structure 1 and / or rotate around the central axis of outer tube structure 1. Imaging structure 3 may include torque transmission tube 31, optical fiber, and imaging probe 32. Torque transmission tube 31 is sleeved on optical fiber, and imaging probe 32 is connected to the distal end of optical fiber. Torque transmission tube 31 can protect optical fiber and drive the movement of optical fiber and imaging probe 32. During use, the torque transmission tube 31 drives optical fiber and imaging probe 32 to move and / or rotate axially, thereby facilitating the imaging probe 32 to scan the inside of blood vessels.

[0099] The protective sleeve 6 is fitted onto the outer wall of the connector 4, and the protective cover 7 is detachably fastened to the near end interface of the connector 4. The protective cover 7 can prevent dust from entering the connector 4 and protect the interior of the outer tube structure 1 from contamination.

[0100] In use, the outer tube structure 1 can be inserted into the corresponding lesion location under the guidance of the guidewire tip 2. Since the outer tube structure 1 is spliced ​​from the proximal tube 11 and the distal tube 12, it can ensure both pushing efficiency and protection of intracranial blood vessels. After the outer tube structure 1 is inserted, the imaging structure 3 can move the imaging probe to the distal end of the lesion. Through the torque transmission tube 31, the imaging probe 32 is driven to rotate and retract simultaneously to perform a 360° scan of the lesion area, thereby imaging the lesion area. The outer tube structure prepared by the above method can improve both the smoothness of the splicing joint and the reliability of the connection at the splicing joint, overcoming the contradiction between the smoothness of the splicing joint and the reliability of the connection. It avoids damage to intracranial blood vessels during the outer tube pushing process and also avoids breakage or detachment of the splicing joint during the outer tube pushing process.

[0101] In this embodiment, the effective length of the OCT imaging catheter can be L1, with L ranging from 1800mm to 1900mm. The effective length of the OCT imaging catheter refers to the length that can be inserted into the human body. The length of the hydrophilic coating is L2, which can range from 1450mm to 1550mm. The portion of the outer tube structure 1 near the guidewire tip 2 is the imaging window 14, which refers to the distal end of the outer tube structure 1 where the probe can be pulled back. The length of the imaging window 14 can be L3, ranging from 95mm to 105mm. The maximum outer diameter D1 of the outer tube structure 1 where the imaging window 14 is located is 0.43mm to 0.49mm, and the maximum outer diameter D2 of the entire outer tube structure 1 is 0.43mm to 0.49mm. The length of the guidewire tip 2 can range from 12mm to 18mm.

[0102] like Figure 7 As shown, in this embodiment, the outer tube structure 1 is provided with an axis marker band 13. The physician can determine the insertion position of the guidewire tip 2 by observing the axis marker band 13. For example, when the axis marker band 13 is pushed to the puncture position, it indicates that the guidewire tip 2 is about to enter a thinner artery, thus visually reminding the physician to slow down the pushing speed of the outer tube structure 1. The axis marker band 13 can be fixed to the proximal outer wall of the outer catheter 10 by laser printing, ink printing, or welding, and is set around the entire circumference, allowing the physician to observe it from any angle. The distance between the axis marker band 13 and the distal end of the guidewire tip 2 can be 1450mm to 1550mm.

[0103] like Figure 6 As shown, in this embodiment, the torque transmission tube 31 can be a spring tube. A first developing ring 33 and a second developing ring 34 are spaced apart on the outer wall of the torque transmission tube 31. The first developing ring 33 is positioned close to the imaging probe 32 to mark its location. The second developing ring 34 is positioned near the proximal end of the first developing ring 33. The distance between the first developing ring 33 and the second developing ring 34 can be L5, ranging from 37mm to 43mm, or from 57mm to 63mm. The distance between the imaging probe 32 and the distal end of the guide wire head 2 can be L6, ranging from 17mm to 20mm. The distance between the first developing ring 33 and the imaging probe 32 can be L7, which can be 1mm.

[0104] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for preparing an outer tube structure, characterized in that, include: Preparation of proximal and distal tubes; The distal end of the proximal tube is machined to form a first step, and the proximal end of the distal tube is machined to form a second step that matches the size of the first step. Laser cladding is performed on the first step and the second step to form laser molten pools for the first step and the second step; Axial vibration and radial stamping are applied to the laser molten pool to weld the first step and the second step together.

2. The method for preparing the outer tube structure according to claim 1, characterized in that, The laser cladding of the first and second steps to form a first laser molten pool and a second laser molten pool, specifically includes: using a wavelength of 1070nm, a power range of 180W to 220W, and a power of 70-90J / mm². 3 Low-energy-density lasers are used to perform laser cladding on the first and second steps.

3. The method for preparing the outer tube structure according to claim 2, characterized in that, A checkerboard scanning strategy was used to perform laser cladding on the first and second steps.

4. The method for preparing the outer tube structure according to any one of claims 1-3, characterized in that, The application of axial vibration and radial stamping to the laser molten pool specifically includes: applying ultrasonic vibration to the laser molten pool in the axial direction, wherein the vibration frequency range of the ultrasonic vibration is 33.25 kHz to 36.75 kHz; and applying high-frequency micro-stamping to the laser molten pool in the radial direction, wherein the pressure range of the high-frequency micro-stamping is 50 MPa to 100 MPa, and the stamping frequency of the high-frequency micro-stamping is 700 times / second to 1000 times / second.

5. The method for preparing the outer tube structure according to any one of claims 1-3, characterized in that, After welding the first step and the second step together, the process also includes: The first and second steps after welding are subjected to an annealing process, wherein the annealing process includes: heating to 350°C at 10°C / min and holding at that temperature for 2 hours, followed by slow cooling at 5°C / min. And / or, the annealing process is a gradient annealing process.

6. The method for preparing the outer tube structure according to claim 1, characterized in that, The distal end of the proximal tube is machined to form a first step, and the proximal end of the distal tube is machined to form a second step that matches the size of the first step. Specifically, this includes: The outer wall of the near-end tube is machined to form a first step, and the inner wall of the far-end tube is machined to form a second step that matches the size of the first step.

7. The method for preparing the outer tube structure according to claim 6, characterized in that, The outer surface of the distal end of the proximal tube is mechanically stripped away at half the wall thickness to form the first step, and the inner surface of the proximal end of the distal tube is mechanically stripped away at half the wall thickness to form the second step. And / or, the overlap dimension of the first step and the second step in the axial direction ranges from 6 mm to 7 mm.

8. An outer tube structure, characterized in that, The outer tube structure is prepared by the method of any one of claims 1 to 7, wherein the outer tube structure comprises: The proximal end has a tube (11), and the distal end has a first step (111); The distal end of the tube (12) has a second step (121) formed at the proximal end. The second step (121) is adapted to the size of the first step (111). The first step (111) and the second step (121) are suitable for insertion and mating.

9. The outer tube structure according to claim 8, characterized in that, The proximal tube (11) includes an inner layer (101), a middle layer (102), and an outer layer (103) arranged sequentially from the inside to the outside. The inner layer (101) is made of polytetrafluoroethylene, the middle layer (102) is made of stainless steel braided wire, and the outer layer (103) is made of polyimide. The distal tube (12) is made of polyether block polyamide. And / or, the outer wall of the distal end of the proximal tube (11) is provided with a hydrophilic coating, and the outer wall of the distal tube (12) is provided with a hydrophilic coating.

10. An OCT imaging catheter, characterized in that, Includes the outer tube structure (1) as described in any one of claims 8 to 9.

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