Method for making cannula, medical cannula and catheter pump

Abstract

The present invention discloses a method for manufacturing a tube body with a three-layer structure and a medical cannula and a catheter pump, the method comprising at least a preset process for forming an outer structural layer on a core rod, the preset process comprising: obtaining a fan-shaped sheet, closing the fan-shaped sheet along the circumference of a variable diameter section, and limiting and fixing it on the outer side of the variable diameter section to obtain a tapered tube; obtaining a first tube and a second tube by extrusion process, respectively sleeve the first tube on the outer side of a first constant diameter section, sleeve the second tube on the outer side of a second constant diameter section, and make the two ends of the tapered tube abut the first tube and the second tube respectively; obtaining a first heat shrink tube, sleeve the first heat shrink tube on the outer side of the core rod, and detaching it after the heat shrink molding is in place. The application is helpful to improve the production efficiency and yield of the product.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, and in particular to a method for making a cannula, a medical cannula and a catheter pump. Background Art

[0002] Medical cannulas generally include two constant diameter tube sections with different outer diameters, and a variable diameter tube section connected between the two constant diameter tube sections. During the molding process of medical cannulas, the connection between the constant diameter tube section and the variable diameter tube section is a manufacturing difficulty. Taking the drainage tube in the medical cannula as an example, the variable diameter tube section in the drainage tube is used to provide a gradually increasing blood drainage area. The constant diameter tube section with a smaller outer diameter in the drainage tube is a straight section, and the constant diameter tube section with a larger outer diameter is a clamp section. The clamp section is used to connect to the extracorporeal circulation pipeline, and its inner wall does not contain a metal layer for reinforcement, but only contains a polymer material layer, and the wall thickness is relatively thick, which is suitable for being clamped and deformed by hemostatic forceps to shut off the pipeline.

[0003] In the prior art, the manufacturing process of the constant diameter pipe section and the variable diameter pipe section includes, for example, the dipping process of CN115916294A or the heat shrinking process of CN112643990B.

[0004] The general process of the dip coating process is: the core rod is slowly lowered at a certain speed into an organic solvent in which a high molecular polymer is dissolved. After staying for a certain period of time, the core rod is raised at a constant and slow speed and placed in an oven for baking to accelerate the volatilization of the solvent. After the solvent evaporates, a uniform high molecular polymer layer is left on the core rod. Then, the above steps are repeated several times to form an inner polymer layer. Then, the intermediate metal reinforcement layer is sleeved outside the inner polymer layer, and the dip coating operation process of the inner polymer layer is repeated to obtain an outer polymer layer. The advantages of this process are: the final cannula has a good consistency in appearance and structure, the straight section and the reducer section are integrally formed, no traces of joining can be seen, and the tube wall can be made very thin. The disadvantage is: bubbles are easily formed in the tube wall, which leads to structural defects. This structural defect will cause the strength of the cannula to decrease, which will lead to problems such as cannula breakage when bending and bubble precipitation. Therefore, the efficiency and yield are low.

[0005] The general process of the heat shrink process is: the reducer section and the straight section are two independent sections before splicing, and the two are connected by heat shrinking process after being plugged in. The advantage of this process is that the production efficiency and yield are high. Because the straight section adopts the extrusion process to make the inner and outer polymer tubes, and then the inner polymer extrusion tube, the metal spring wire, and the outer polymer are successively put into the mandrel, and then the heat shrink tube is put on, and then put into the heat reflow equipment for heat reflow processing, the efficiency and yield can be guaranteed. The disadvantage is that since the extrusion process cannot make a large taper reducer, the reducer section can only be made by injection molding, resulting in high cost. In addition, the injection molding process requires a higher hardness of the material (higher than the hardness of the straight section), resulting in that when heat shrinking, the two can only be flush on the inner wall of the mandrel, and the outer wall will form a clear step visible to the naked eye. This step not only affects the visual sensory effect and the push feel, but also forms an obvious hardness gradient, which makes it easy for the tube to be folded when pushing the intubation. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for manufacturing a cannula, a medical cannula, and a catheter pump, aiming to improve the manufacturing efficiency and manufacturing yield of a tube body with a three-layer structure.

[0007] To achieve the above-mentioned purpose, the present invention proposes a method for making a cannula, which includes sequentially forming an inner structural layer, an intermediate reinforcement layer and an outer structural layer of a tube body on a mandrel. The mandrel includes a first constant diameter section and a second constant diameter section with different outer diameters, and a variable diameter section connected between the first constant diameter section and the second constant diameter section. The method includes at least a preset process for forming an outer structural layer on the mandrel, and the preset process includes: obtaining a fan-shaped sheet, closing the fan-shaped sheet along the circumference of the variable diameter section, and limiting and fixing it on the outside of the variable diameter section to obtain a tapered tube. The first tube and the second tube are obtained by extrusion molding, and the first tube is respectively sleeved on the outside of the first constant diameter section, and the second tube is sleeved on the outside of the second constant diameter section, and the two ends of the tapered tube are respectively abutted against the first tube and the second tube. A first heat shrink tube is obtained, and the first heat shrink tube is sleeved on the outside of the mandrel, and is detached after the heat shrink molding is in place.

[0008] In the technical solution provided by the present invention, the pipe body has a first constant diameter pipe section corresponding to the first constant diameter section, a second constant diameter pipe section corresponding to the second constant diameter section, and a variable diameter pipe section corresponding to the variable diameter section. At least the outer structural layer of the first constant diameter pipe section and the second constant diameter pipe section is made of the first pipe material and the second pipe material. Since the first pipe material and the second pipe material are made by the extrusion process, the shape and size are regular, and the production efficiency and production yield are relatively high. The variable diameter pipe section is formed by closing the prefabricated fan-shaped sheets to avoid structural defects such as bubbles formed in the pipe wall, and compared with the injection molding process, it helps to reduce the requirements for material hardness and reduce the production cost, so that when the first pipe material, the second pipe material and the conical pipe material are hot compressed, the inner and outer surfaces of the three will not form obvious steps and hardness gradients, which helps to improve the final use quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic flow chart of a preset process in the method provided by the present invention;

[0010] Figure 2 A schematic diagram of the structure of a core rod in the method provided by the present invention;

[0011] Figure 3 A schematic diagram of the manufacturing process of the inner structural layer in the method provided by the present invention;

[0012] Figure 4 for Figure 3 A schematic diagram of the manufacturing process of another embodiment of step (b);

[0013] Figure 5 This is a schematic diagram of the structure of the inner structural layer in the method provided by the present invention;

[0014] Figure 6 A schematic diagram of the manufacturing process of the intermediate reinforcement layer in the method provided by the present invention;

[0015] Figure 7 A schematic diagram of the manufacturing process of the outer structural layer in the method provided by the present invention;

[0016] Figure 8 for Figure 7 A schematic diagram of the structure of the outer structural layer of the tube body obtained by manufacturing;

[0017] Fig. 9 This is a schematic diagram of the cross-sectional structure of a tube body manufactured by the method provided by the present invention;

[0018] Fig.10 A schematic diagram of the process of manufacturing a fan-shaped sheet according to a first embodiment of the present invention;

[0019] Fig.11A schematic diagram of the process of manufacturing a fan-shaped sheet according to a second embodiment of the present invention;

[0020] Fig.12 A schematic diagram of the process of manufacturing a tapered tube according to a first embodiment of the present invention;

[0021] Fig.13 A schematic diagram of the process of manufacturing a tapered tube according to a second embodiment of the present invention;

[0022] Fig.14 A schematic diagram of the process of manufacturing a tapered tube according to a third embodiment of the present invention;

[0023] Fig.15 Schematic diagram of the structure of the catheter pump. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figures 1 to 15 The present invention provides a method for manufacturing a cannula. The cannula is specifically a tube body 100 having a three-layer structure. Fig. 9 As shown, the pipe body 100 with a three-layer structure (hereinafter referred to as the pipe body 100 for ease of understanding) includes a first constant diameter pipe section 110, a reducing pipe section 130 and a second constant diameter pipe section 120 arranged in sequence along its axial direction, and the pipe diameters (outer diameter and / or inner diameter) of the first constant diameter pipe section 110 and the second constant diameter pipe section 120 are different. For ease of understanding, in the following embodiments, the pipe diameter of the first constant diameter pipe section 110 is smaller than the pipe diameter of the second constant diameter pipe section 120. At this time, in the direction from the first constant diameter pipe section 110 to the second constant diameter pipe section 120, the pipe diameter of the reducing pipe section 130 is gradually increased. It should be noted that this design does not constitute a restriction on the number of pipe sections of the pipe body 100. That is, in actual application, the pipe body 100 can have and only have three pipe sections (the first constant diameter pipe section 110, the reducing pipe section 130 and the second constant diameter pipe section 120) along its axial direction. Or in other applications, the pipe body 100 may also be provided with, for example, five pipe sections (the first constant diameter pipe section 110, the reducing pipe section 130, the second constant diameter pipe section 120, the reducing pipe section 130 and the first constant diameter pipe section 110) along its axial direction, without limitation.

[0026] In addition, the pipe body 100 has a three-layer structure, but it is not limited to that each of the above pipe sections of the pipe body 100 must have a three-layer structure, or must have only a three-layer structure. According to actual needs, at least one pipe section of the pipe body 100 can have a three-layer structure, or a structure with more than three layers.

[0027] Specifically in this design, please combine Figures 8 to 9 The first constant diameter pipe section 110 includes a first inner structural layer 111, a first intermediate reinforcement layer 112, and a first outer structural layer 113 which are sequentially arranged from the inside to the outside along the radial direction thereof. The second constant diameter pipe section 120 includes a second inner structural layer 121 and a second outer structural layer 122 which are sequentially arranged from the inside to the outside along the radial direction thereof. The variable diameter pipe section 130 includes a third inner structural layer 131, a second intermediate reinforcement layer 132, and a third outer structural layer 133 which are sequentially arranged from the inside to the outside along the radial direction thereof.

[0028] After the tube body 100 is manufactured and formed, the first inner structural layer 111, the second inner structural layer 121 and the third inner structural layer 131 together constitute the inner structural layer of the entire tube body 100. The first middle reinforcement layer 112 and the second middle reinforcement layer 132 together constitute the middle reinforcement layer of the entire tube body 100. The first outer structural layer 113, the second outer structural layer 122 and the third outer structural layer 133 together constitute the outer structural layer of the entire tube body 100.

[0029] It should be noted that the inner structural layer and the outer structural layer can generally be made of the same polymer material, and the middle reinforcement layer is generally made of metal material.

[0030] The method of the present invention includes sequentially forming an inner structural layer, an intermediate reinforcement layer and an outer structural layer of a tube body 100 on a mandrel 200, which may specifically include:

[0031] A core rod 200 is provided. The core rod 200 includes a first constant diameter section 210 and a second constant diameter section 220 with different outer diameters, and a variable diameter section 230 connected between the first constant diameter section 210 and the second constant diameter section 220 .

[0032] The first inner structural layer 111 , the second inner structural layer 121 and the third inner structural layer 131 are respectively formed on the outer sides of the first constant diameter section 210 , the second constant diameter section 220 and the variable diameter section 230 .

[0033] The first middle reinforcement layer 112 and the second middle reinforcement layer 132 are respectively formed on the outer sides of the first inner structural layer 111 and the third inner structural layer 131 .

[0034] The first outer structural layer 113 , the second outer structural layer 122 and the third outer structural layer 133 are respectively formed on the outer sides of the first middle reinforcing layer 112 , the second middle reinforcing layer 132 and the second inner structural layer 121 .

[0035] Please combine Figure 2 The first constant diameter section 210 of the mandrel 200 corresponds to the first constant diameter pipe section 110 used to form the pipe body 100, but the axial length of the first constant diameter section 210 is set to be greater than the length of the first constant diameter pipe section 110. The second constant diameter section 220 corresponds to the second constant diameter pipe section 120 used to form the pipe body 100, but the axial length of the second constant diameter section 220 is set to be greater than the length of the second constant diameter pipe section 120. The reduced diameter section 230 corresponds to the reduced diameter pipe section 130 used to form the pipe body 100. When the pipe body 100 is finally formed, the mandrel 200 will be detached, such as Figures 8 to 9 steps.

[0036] In addition, the method of the present invention further includes a preset process, which can be selectively applied to respectively manufacture and form the inner structural layer and / or the outer structural layer of the tube body 100, and specifically includes:

[0037] Step S1: Obtain a fan-shaped sheet, which has a short arc side 301 and a long arc side 302 arranged opposite to each other in the radial direction, and two straight sides 303 connecting the short arc side 301 and the long arc side 302. Close the fan-shaped sheet along the circumference of the diameter-changing section 230, and limit and fix it on the outside of the diameter-changing section 230 to obtain a tapered tube.

[0038] Step S2: Obtain the first tube and the second tube by extrusion process, respectively sleeve the first tube on the outside of the first constant diameter section 210, sleeve the second tube on the outside of the second constant diameter section 220, and make the two ends of the conical tube abut the first tube and the second tube respectively.

[0039] Step S3: Obtain a first heat shrink tube, sleeve the first heat shrink tube on the outer side of the core rod 200, and remove it after heat shrinking and molding in place.

[0040] Please combine Figures 2 to 5 When the preset process is applied to form the inner structural layer of the tube body 100, the above steps S1 to S3 may specifically include:

[0041] Step S11: Obtain an inner layer fan-shaped sheet 311, wherein the inner layer fan-shaped sheet 311 has a short arc side 301 and a long arc side 302 arranged opposite to each other in the radial direction, and two straight sides 303 connecting the short arc side 301 and the long arc side 302. The inner layer fan-shaped sheet 311 is closed along the circumference of the diameter-changing section 230, and is fixed at a position outside the diameter-changing section 230 to obtain an inner layer conical tube 321.

[0042] Step S21: obtaining a first inner layer tube 331 and a second inner layer tube 341 by extrusion process, respectively sleeve the first inner layer tube 331 on the outside of the first constant diameter section 210, sleeve the second inner layer tube 341 on the outside of the second constant diameter section 220, and make the two ends of the inner tapered tube 321 abut against the first inner layer tube 331 and the inner second tube respectively; and,

[0043] Step S31: Obtain the first inner layer heat shrink tube 351, sleeve the first inner layer heat shrink tube 351 on the outer side of the core rod 200, and remove it after heat shrinking and molding in place.

[0044] like Figure 3 As shown in (a), after providing the mandrel 200, it is also necessary to obtain the inner fan-shaped sheet 311, the first inner tube 331 and the second inner tube 341. It should be noted that there is no restriction on the order of obtaining the inner fan-shaped sheet 311, the first inner tube 331 and the second inner tube 341. They can be obtained in a staggered order or simultaneously as needed. Among them, since the diameters of the first inner tube 331 and the second inner tube 341 are constant, they can be directly obtained by extrusion process. The first inner tube 331 and the second inner tube 341 obtained by extrusion process have sufficient production efficiency and production yield.

[0045] In one embodiment, the step of obtaining the inner fan-shaped sheet 311 includes: obtaining a rectangular sheet 520; and cutting the rectangular sheet 520 to obtain the inner fan-shaped sheet 311. In this embodiment, after the rectangular sheet 520 is obtained by, for example, punching, cutting, etc., a cutting line X is determined on the rectangular sheet 520 manually or by automatic program compilation, and cutting is performed manually or automatically along the cutting line X, so that the inner fan-shaped sheet 311 can be directly cut out. The above-mentioned specific cutting method can be, but is not limited to, laser cutting, die cutting, punching cutting, etc.

[0046] Please combine Fig.10 The step of obtaining the rectangular sheet 520 includes: obtaining a third tube 510 made by an extrusion process, cutting the third tube 510 along a generatrix thereof and then unfolding it to obtain the rectangular sheet 520. Alternatively, obtaining a second mold with a rectangular groove, injecting a material stock solution into the rectangular groove, and demolding the material stock solution after solidification to form the rectangular sheet 520.

[0047] In this embodiment, the third tube 510 can also be obtained by extrusion process. A generatrix of the third tube 510 is used as the cutting line X, and the third tube 510 is cut to obtain a rectangular sheet 520 that is roughly rectangular. Relying on the mature technology of the extrusion process, it can be ensured that the wall thickness of the rectangular sheet 520 is relatively uniform. Alternatively, firstly, the required second mold is made, and the second mold is roughly plate-shaped or block-shaped, and one or at least two rectangular grooves are evenly opened on one surface. The shape and size of the rectangular groove are equivalent to the rectangular sheet 520 to be prepared. Then, by injecting the material stock solution into the rectangular groove, the rectangular sheet 520 can be obtained after the material stock solution is solidified and demolded.

[0048] Alternatively, please combine Fig.11 In another embodiment, the step of obtaining the inner fan-shaped sheet 311 includes: obtaining a first mold 530 having a fan-shaped groove 540, injecting a material solution into the fan-shaped groove 540, and demolding the material solution after solidification to form the inner fan-shaped sheet 311. In this embodiment, the first mold 530 is roughly plate-shaped or block-shaped in structure, and one or at least two fan-shaped grooves 540 are uniformly opened on one surface. The shape and size of the fan-shaped groove 540 are both equivalent to the inner fan-shaped sheet 311 to be prepared. Then, by injecting the material solution into the fan-shaped groove 540, the inner fan-shaped sheet 311 can be obtained after the material solution is solidified and demolded.

[0049] The material stock solution is, for example, a polymer solution prepared by dissolving a polymer material in a volatile solvent. The polymer material may be, but is not limited to, TPU (Thermoplastic Urethane), PVC (Polyvinyl Chloride), etc. The volatile solvent may be, but is not limited to, DHF, DMF (N,N-dimethylformamide), DMAC (N,N-dimethylacetamide), or acetone organic solvent, etc. After the material stock solution is injected into each rectangular groove or each fan-shaped groove 540, it is left to stand for a preset time, and then demolded after the volatile solvent is fully evaporated, and the rectangular sheet 520 or the inner fan-shaped sheet 311 can be obtained accordingly. This method is conducive to the mass production of the rectangular sheet 520 or the inner fan-shaped sheet 311.

[0050] In step S11, first, the short arc side 301 and the long arc side 302 of the inner layer fan-shaped sheet 311 are roughly aligned with the two ends of the variable diameter section 230, and then closed circumferentially, and fixed on the outer side of the variable diameter section 230 to obtain the inner layer conical tube 321. After the inner layer fan-shaped sheet 311 is closed, it is necessary to perform a pre-fixing operation on the inner layer fan-shaped sheet 311 to prevent it from loosening, and the specific method includes:

[0051] Please combine Fig.12 In one embodiment, an adhesive 550 is provided and applied to at least one straight edge 303. Then, the two straight edges 303 of the inner fan-shaped sheet 311 are glued to obtain the inner tapered tube 321. In this embodiment, before the inner fan-shaped sheet 311 is closed, the adhesive 550 can be applied to at least one straight edge 303 of the inner fan-shaped sheet 311 in advance. The adhesive 550 is generally an organic solvent, and can be completely coated on the entire straight edge 303 according to actual needs, or can be locally dotted. In this way, when the inner fan-shaped sheet 311 is closed circumferentially, the two straight edges 303 can be tightly fitted under the adhesive action of the adhesive 550 to form the desired inner tapered tube 321.

[0052] Alternatively, please combine Figure 13 to Figure 14 In another embodiment, a second heat shrink tube 560 is provided, and the second heat shrink tube 560 is sleeved on the outer side of the inner fan-shaped sheet 311 after closing, and is detached after heat shrinking and molding in place, so as to obtain the inner tapered tube 321. In this embodiment, after the closing operation of the inner fan-shaped sheet 311 is completed, the second heat shrink tube 560 can be sleeved on the outer side of the inner fan-shaped sheet 311 to achieve basic positioning of the inner fan-shaped sheet 311. Then, by heat shrinking the second heat shrink tube 560, the closed inner fan-shaped sheet 311 is squeezed by the shrunk second heat shrink tube 560, and the two straight edges 303 are joined at high temperature to form the inner tapered tube 321. When the inner tapered tube 321 is molded in place, the second heat shrink tube 560 needs to be removed.

[0053] When there is one second heat shrink tube 560, the second heat shrink tube 560 at least in the axial direction (i.e., the tube length) needs to be no less than the axial dimension of the inner tapered tube 321 / inner fan-shaped sheet 311, so as to be able to completely cover the outer side of the entire inner fan-shaped sheet 311, and to obtain the inner tapered tube 321 with a size that meets the requirements. Alternatively, when there are at least two second heat shrink tubes 560, the tube length of each second heat shrink tube 560 can be set to be less than the axial dimension of the inner tapered tube 321 / inner fan-shaped sheet 311, and each second heat shrink tube 560 is arranged in sequence along the tube length direction of the inner tapered tube 321. At this time, the specific number of the second heat shrink tubes 560 is not limited, but in terms of arrangement, at least one second heat shrink tube 560 needs to be sufficiently close to the short arc edge 301 of the inner fan-shaped sheet 311, and another second heat shrink tube 560 needs to be sufficiently close to the long arc edge 302 of the inner fan-shaped sheet 311.

[0054] In step S21, the first inner layer tube 331 needs to be sleeved so that its end portion at least partially abuts against the end portion of the adjacent inner layer conical tube 321, and the second inner layer tube 341 needs to be sleeved so that its end portion at least partially abuts against the end portion of the adjacent inner layer conical tube 321. In this process:

[0055] like Figure 3 As shown in (b), the end of the first inner tube 331 can be directly overlapped with the end of the inner tapered tube 321. Similarly, the end of the second inner tube 341 can be directly overlapped with the end of the inner tapered tube 321. Figure 4 As shown, the first inner layer tube 331 can extend to partially cover the outer side of the inner layer tapered tube 321. Similarly, the second inner layer tube 341 can extend to partially cover the outer side of the inner layer tapered tube 321. At this time, a first inner layer gap 361 may be formed at the non-overlapping portion between the first inner layer tube 331 and the inner layer tapered tube 321, or between the first inner layer tube 331 and the outer wall of the first constant diameter section 210. Alternatively, a second inner layer gap 371 may be formed at the non-overlapping portion between the second inner layer tube 341 and the inner layer tapered tube 321, or between the second inner layer tube 341 and the outer wall of the second constant diameter section 220.

[0056] To this end, in a further solution, the wall thickness of the inner tapered tube 321 and the wall thickness of the first inner tube 331 and / or the second inner tube 341 abutting therewith are set to be different. By setting the wall thickness differently, when the first inner heat shrink tube 351 is subsequently heat-shrunk, the excess material at the abutment can be filled into the first inner gap 361 / the second inner gap 371, which helps to eliminate the first inner gap 361 / the second inner gap 371, thereby helping to avoid the inner and outer surfaces of the inner structural layer of the tube body 100 from being dented due to the filling of materials at other positions into the first inner gap 361 / the second inner gap 371, and helping to ensure that the entire outer surface of the inner structural layer of the tube body 100 is smooth and flat.

[0057] Furthermore, when the diameter of the first constant diameter pipe section 110 to be manufactured as described above is smaller than the outer diameter of the second constant diameter pipe section 120, corresponding to the diameter of the first inner layer pipe 331 being smaller than the diameter of the second inner layer pipe 341, the wall thickness of the inner layer conical pipe 321 can be specifically set to be smaller than the wall thickness of the second inner layer pipe 341, and the wall thickness of the inner layer conical pipe 321 can be set to be greater than the wall thickness of the first inner layer pipe 331, which helps to fully eliminate the first inner layer gap 361 between the first inner layer pipe 331 and the inner layer conical pipe 321, and the second inner layer gap 371 between the second inner layer pipe 341 and the inner layer conical pipe 321.

[0058] In step S31, Figure 3 Middle (c) to Figure 3 In (d), after the first inner layer heat shrink tube 351 heat-compresses the first inner layer tube 331, the inner layer conical tube 321 and the second inner layer tube 341 in place, and before or after the first inner layer heat shrink tube 351 is removed, the inner layer heat shrink fillet 381 formed by the end of the first inner layer tube 331 away from the inner layer conical tube 321 and the end of the second inner layer tube 341 away from the inner layer conical tube 321 can be cut, and finally the following is obtained: Figure 5 Similarly, the heat shrink fillet formed by the second heat shrink tube 560 can also be cut in advance before the next step is performed. Or it can be cut together with the inner heat shrink fillet 381 formed by the first inner heat shrink tube 351 in this step.

[0059] Based on one or more of the above embodiments, when Figure 5 After the inner structural layer of the tube body 100 is completed, please refer to Figure 6 The steps of making the middle reinforcement layer include: obtaining the reinforcement material 410, and covering the reinforcement material 410 on the outer side of the inner structural layer facing away from the variable diameter section 230 and the outer side facing away from the first constant diameter section 210 respectively.

[0060] In this embodiment, the reinforcing material 410 may be specifically but not limited to a metal material. The metal material may be in any suitable state, such as a sheet, a mesh, a filament, a spiral, etc. The reinforcing material 410 covers the outer side of the first inner structural layer 111 to form the first intermediate reinforcing layer 112, covers the outer side of the third inner structural layer 131 to form the second intermediate reinforcing layer 132, and basically does not need to cover the outer side of the second inner structural layer 121. The final production is as follows Figure 6 The middle reinforcement layer of the pipe body 100 is shown.

[0061] Next, the outer structural layer of the tube body 100 can be manufactured by the above-mentioned preset process. Figure 2 , Figures 6 to 9 , each step S1 to S3 of the above preset process may specifically include:

[0062] Step S12: obtaining an outer layer fan-shaped sheet 312, wherein the outer layer fan-shaped sheet 312 has a short arc side 301 and a long arc side 302 which are arranged opposite to each other in the radial direction, and two straight sides 303 connecting the short arc side 301 and the long arc side 302, closing the outer layer fan-shaped sheet 312 along the circumferential direction of the variable diameter section 230, and limiting and fixing it on the outer side of the second intermediate reinforcement layer 132, so as to obtain an outer layer conical tube 322;

[0063] Step S22: obtaining a first outer layer tube 332 and a second outer layer tube 342 by extrusion molding, respectively sleeve the first outer layer tube 332 on the outside of the first inner structure layer 111, sleeve the second outer layer tube 342 on the outside of the second inner structure layer 121, and make the two ends of the outer tapered tube 322 abut against the first outer layer tube 332 and the outer second tube; and,

[0064] Step S32: Obtain the first outer heat shrink tube 352, sleeve the first outer heat shrink tube 352 on the outer sides of the inner structural layer and the middle reinforcement layer, and detach it after heat shrinking and molding in place.

[0065] In this embodiment, the same contents as those of producing the inner structural layer are involved, for example: the first outer layer tube 332, the second outer layer tube 342, the method of obtaining the outer fan-shaped sheet 312, the closing and anti-loosening pre-fixing operation of the outer conical tube 322, etc., all of which can be found in the above description and will not be repeated here.

[0066] It should be noted that the outer structural layer and the inner structural layer are slightly different mainly in the size of the source material, for example, the straight edge and arc edge lengths of the outer sector sheet 312 and the inner sector sheet 311 are different, the inner diameters of the inner and outer tubes sleeved on the same section of the mandrel 200 are different, etc. This is mainly due to the inner and outer source materials being used to form the inner and outer structural layers of the tube body 100 respectively.

[0067] However, it is worth noting that the source materials of the outer structural layer and the inner structural layer in the same section are obtained by the same manufacturing process. For example, the outer fan-shaped sheet 312 and the inner fan-shaped sheet 311 are made by cutting rectangular sheets or forming in a mold with fan-shaped grooves, and the four tubes 331, 341, 332, 342 are made by extrusion. This is conducive to the scale of source materials and is beneficial to improving production efficiency. Furthermore, in the production process from the fan-shaped sheets 311, 312 to the conical tubes 321, 322, the same method is also used for the pre-fixing operation to prevent looseness. Therefore, on the whole, the source materials used to make the tube body 100 can be quickly obtained by only two very simple and technically mature production processes, and the production methods for the same sections of the inner and outer structural layers are also the same, which greatly reduces the production cost and cycle of the tube body 100 and improves production efficiency and yield.

[0068] In step S22, the first outer layer tube 332 needs to be sleeved so that its end portion at least partially abuts against the end portion of the adjacent outer layer conical tube 322, and the second outer layer tube 342 needs to be sleeved so that its end portion at least partially abuts against the end portion of the adjacent outer layer conical tube 322. In this process:

[0069] like Figure 7 As shown in (b), the end of the first outer tube 332 can be directly overlapped with the end of the outer conical tube 322. Similarly, the end of the second outer tube 342 can be directly overlapped with the end of the outer conical tube 322. Figure 4 , the first outer layer tube 332 may extend to partially cover the outer side of the outer layer conical tube 322. Similarly, the second outer layer tube 342 may extend to partially cover the outer side of the outer layer conical tube 322. At this time, a first outer layer gap 362 may be formed at the non-overlapping portion between the first outer layer tube 332 and the outer layer conical tube 322, or between the first outer layer tube 332 and the outer wall of the first intermediate reinforcement layer 112. Alternatively, a second outer layer gap 372 may be formed at the non-overlapping portion between the second outer layer tube 342 and the outer layer conical tube 322, or between the second outer layer tube 342 and the outer wall of the second inner structural layer 121.

[0070] To this end, in a further solution, the wall thickness of the outer conical tube 322 and the wall thickness of the first outer tube 332 and / or the second outer tube 342 abutting therewith are set to be different. By setting the wall thickness differently, when the first outer heat shrink tube 352 is subsequently heat-shrunk, the excess material at the abutment can be filled into the first outer gap 362 / second outer gap 372, which helps to eliminate the first outer gap 362 / second outer gap 372, thereby helping to avoid the inner and outer surfaces of the outer structural layer of the tube body 100 from being concave due to the filling of materials at other positions into the first outer gap 362 / second outer gap 372, and helping to ensure that the entire outer surface of the outer structural layer of the tube body 100 is smooth and flat.

[0071] Furthermore, when the diameter of the first constant diameter pipe section 110 to be manufactured as described above is smaller than the outer diameter of the second constant diameter pipe section 120, the diameter of the first outer layer pipe 332 is smaller than the diameter of the second outer layer pipe 342, and the wall thickness of the outer layer conical pipe 322 can be specifically set to be smaller than the wall thickness of the second outer layer pipe 342, and the wall thickness of the outer layer conical pipe 322 is greater than the wall thickness of the first outer layer pipe 332, which helps to fully eliminate the first outer layer gap 362 between the first outer layer pipe 332 and the outer layer conical pipe 322, and the second outer layer gap 372 between the second outer layer pipe 342 and the outer layer conical pipe 322.

[0072] In step S32, combined Figure 7 Middle (c) to Figure 7 In (d), after the first outer layer heat shrink tube 352 heat-compresses the first outer layer tube 332, the outer layer conical tube 322 and the second outer layer tube 342 in place, and before or after the first outer layer heat shrink tube 352 is removed, the outer layer heat shrink fillet 382 formed by the end of the first outer layer tube 332 away from the outer layer conical tube 322 and the end of the second outer layer tube 342 away from the outer layer conical tube 322 can be cut, and finally the outer layer heat shrink tube 352 is obtained. Figure 8 Similarly, the heat shrink fillet formed by the second heat shrink tube 560 can also be cut in advance before the next step is performed; or it can be cut together with the outer heat shrink fillet 382 formed by the first outer heat shrink tube 352 in this step.

[0073] In view of the above, when the inner structural layer and the outer structural layer are obtained by the preset process, since the materials of the first inner structural layer 111, the second inner structural layer 121 and the third inner structural layer 131 are the same, when the first heat shrinking process of step S31 is performed, the joint ends between two adjacent sections of the three sections can reach a molecular-level fusion state. Similarly, since the materials of the first outer structural layer 113, the second outer structural layer 122 and the third outer structural layer 133 are the same, when the second heat shrinking process of step S32 is performed, the joint ends between two adjacent sections of the three sections can reach a molecular-level fusion state. Thus, the first constant diameter pipe section 110, the variable diameter pipe section 130 and the second constant diameter pipe section 120 that are finally formed are integrally formed.

[0074] It should be noted that the inner structural layer of the tube body 100 can also be obtained without adopting the above-mentioned preset process, and the inner structural layer can be directly formed on the outer side of the core rod 200 through a dip coating process. Specifically, the core rod 200 can be slowly lowered at a certain speed into an organic solvent (such as the above-mentioned material stock solution) in which a high molecular polymer is dissolved. After staying for a certain period of time, the core rod 200 is raised at a constant and slow speed and placed in an oven for baking to accelerate the volatilization of the solvent. After the solvent evaporates, a uniform high molecular polymer layer is left on the core rod 200. Then repeat the above steps several times to form the inner structural layer.

[0075] It can be understood that the inner structural layer of the tube body 100 manufactured by the dip coating process has better integrity, a smoother inner wall, and a controllable wall thickness. Figure 6 In the manufacturing process of the intermediate reinforcement layer shown, when the reinforcement material 410 is a metal spring wire, the winding of the metal spring wire will hinder the precipitation of bubbles in the inner structural layer, resulting in the formation of bubbles in the inner structural layer. The inner structural layer of the tube body 100 manufactured by the dip coating process is implemented before the manufacturing step of the intermediate reinforcement layer, which can avoid the formation of bubbles in the inner structural layer. The outer structural layer of the tube body 100 manufactured by the preset process is implemented after the manufacturing step of the intermediate reinforcement layer. The prior application of the metal spring wire no longer has any adverse effects on the outer structural layer, taking into account both the manufacturing efficiency and the manufacturing yield.

[0076] Based on one or more of the above embodiments, it can be understood that the tube body 100 formed by the above method can be used as a medical cannula, for example, a medical drainage tube, a tracheal cannula, etc. At this time, the diameter of the first constant diameter tube section 110 is smaller than that of the second constant diameter tube section 120, but the length is greater than the length of the second constant diameter tube section 120. The second constant diameter tube section 120 is used to connect with an external pipeline.

[0077] In this application scenario, the wall thickness of the inner conical tube 321 is greater than the wall thickness of the first inner tube 331 but less than the wall thickness of the second inner tube 341, and the wall thickness of the outer conical tube 322 is greater than the wall thickness of the first outer tube 332 but less than the wall thickness of the second outer tube 342. In actual operation, the second constant diameter tube section 120 needs to be clamped by, for example, hemostatic forceps to shut off the cannula, and no reinforcing material 410 such as metal spring wire is provided in the second constant diameter tube section 120. At this time, the maximum wall thickness of the second constant diameter tube section 120 can make up for the decrease in material toughness caused by the absence of the metal spring wire, ensure that the tube wall is not damaged when clamped, and the tube wall smoothly rebounds to its original state after the clamp is removed. The reducing tube section 130 is a transition section, and its central wall thickness combined with the metal spring wire can improve the push shape of the medical cannula and prevent the medical cannula from bending at the reducing tube section 130 during the intervention process. The thinnest wall thickness of the first constant diameter tube section 110 is matched with the metal spring wire, so that the first constant diameter tube section 110 has both good radial stiffness and flexibility. The good radial stiffness prevents the medical cannula from collapsing radially inward due to negative pressure during operation, while the good flexibility ensures that the medical cannula can adapt to the tortuous trend of the blood vessel, ensures the passability and bending performance of the medical cannula, and realizes smooth intervention.

[0078] The tube body 100 manufactured by the above method can also be applied to the catheter pump 600. Fig.15 As shown, the catheter pump 600 includes a blood inlet cage 610, a bleeding port cage 620, and a cannula made by the above method. At this time, the diameter of the first constant diameter pipe section 110 is greater than that of the second constant diameter pipe section 120, and the length is greater than that of the second constant diameter pipe section 120. The number of the second constant diameter pipe section 120 and the variable diameter pipe section 130 are both two groups, which are respectively arranged at both ends of the first constant diameter pipe section 110. The second constant diameter pipe section 120 in one group is used to connect with the blood inlet cage 610, and the second constant diameter pipe section 120 in the other group is used to connect with the bleeding port cage 620.

[0079] In this application scenario, the relationship between the diameters of the first constant diameter tube segment 110 and the second constant diameter tube segment 120 is opposite to that of the above application scenario. Among them, the first constant diameter tube segment 110 with the largest diameter provides a larger blood flow area, which helps to increase the pump flow rate. The intermediate reinforcement layer configured in the wall of the first constant diameter tube segment 110 provides a strong radial stiffness, which prevents the tube body 100 from radially shrinking due to the suction effect of the impeller on the blood, and ensures the stability of the blood flow channel. The wall of the two second constant diameter tube segments 120 with the smallest diameter does not include an intermediate reinforcement layer for enhancing radial stiffness, so that the second constant diameter tube segment 120 has better radial deformability than the first constant diameter tube segment 110, which is conducive to sleeve the second constant diameter tube segment 120 on the outside of the blood inlet cage 610 and the bleeding port cage 620, and improves the assembly efficiency of the cannula and the blood inlet cage 610 and the bleeding port cage 620.

[0080] The catheter pump 600 can be used as a left ventricular assist device, a right ventricular assist device, a renal pump, etc. as needed. Its interventional procedure, working principle, and the impeller, motor, etc. that must be configured to achieve the blood pumping function can all be selected from any suitable existing solutions and will not be described in detail in this embodiment.

[0081] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for making a cannula, characterized in that: The method comprises sequentially forming an inner structural layer, an intermediate reinforcement layer and an outer structural layer of a tube body on a mandrel, wherein the mandrel comprises a first constant diameter section and a second constant diameter section with different outer diameters, and a variable diameter section connected between the first constant diameter section and the second constant diameter section; The method further comprises at least a preset process for forming the outer structural layer on the mandrel, and the preset process comprises: Obtain a fan-shaped sheet, wherein the fan-shaped sheet has a short arc side and a long arc side that are oppositely arranged in the radial direction, and two straight sides connecting the short arc side and the long arc side, close the fan-shaped sheet along the circumference of the diameter-changing section, and limit and fix it on the outside of the diameter-changing section to obtain a tapered tube; The first tube and the second tube are obtained by extrusion molding, and the first tube is sleeved on the outside of the first constant diameter section, and the second tube is sleeved on the outside of the second constant diameter section, and the two ends of the tapered tube are respectively abutted against the first tube and the second tube; Obtain a first heat shrink tube, sleeve the first heat shrink tube on the outer side of the core rod, and remove it after heat shrinking and molding in place.

2. The method according to claim 1, characterized in that The inner structural layer is also formed by the preset process; or, the inner structural layer is formed on the outer side of the core rod by a dip coating process.

3. The method according to claim 1, characterized in that The step of forming the intermediate reinforcement layer includes: obtaining reinforcement materials, and covering the reinforcement materials on the outer side of the inner structural layer facing away from the variable diameter section and the outer side of the inner structural layer facing away from the first constant diameter section.

4. The method according to claim 1, characterized in that The steps of obtaining the fan-shaped sheet include: Obtain a rectangular sheet; cut the rectangular sheet to obtain the fan-shaped sheet; or, A first mold with a fan-shaped groove is obtained; a material stock solution is injected into the fan-shaped groove, and the mold is demoulded after the material stock solution is solidified to form the fan-shaped sheet.

5. The method according to claim 4, characterized in that The steps to obtain a rectangular sheet include: Obtain a third tube made by extrusion process, cut the third tube along a generatrix thereof and then unfold it to obtain the rectangular sheet; or, A second mold with a rectangular groove is obtained, and a material stock solution is injected into the rectangular groove. After the material stock solution is solidified, the mold is demoulded to form the rectangular sheet.

6. The method according to claim 1, characterized in that The steps to obtain a tapered tube include: The fan-shaped sheet is closed along the circumference of the diameter-changing section, and a pre-fixing operation is performed on the closed fan-shaped sheet to prevent it from loosening; the pre-fixing operation includes: Applying adhesive to at least one of the straight edges of the fan-shaped sheet, and gluing the two straight edges of the fan-shaped sheet to obtain a tapered tube; or, A second heat shrink tube is sleeved on the outer side of the fan-shaped sheet, and is removed after the second heat shrink tube is heat-shrunk and molded into place, so as to obtain a tapered tube.

7. The method according to claim 1, characterized in that The end of the first tube and / or the end of the second tube partially abuts against the end of the adjacent conical tube, and a gap is formed at the non-abutting portion; The wall thickness of the tapered tube is set to be different from the wall thickness of the first tube and / or the second tube abutting therewith.

8. The method according to claim 1, characterized in that The diameter of the first tube is smaller than that of the second tube, and a gap is formed between the first tube and the tapered tube, and between the second tube and the tapered tube. The wall thickness of the tapered tube is smaller than the wall thickness of the second tube, and the wall thickness of the tapered tube is larger than the wall thickness of the first tube.

9. A medical cannula, characterized in that: The medical cannula is manufactured by the method according to any one of claims 1 to 8.

10. A catheter pump, characterized in that: include: Blood inlet cage; Bleeding mouth cage; as well as, The cannula is manufactured by the method according to any one of claims 1 to 8, and the two ends of the cannula are respectively connected to the blood inlet cage and the blood outlet cage.

Images