Apparatus and method for manufacturing multilayer composite medical tube

Abstract

This invention discloses a fabrication apparatus and method for multilayer composite medical tubes, relating to the field of medical tube molding equipment. The apparatus includes a workbench with multiple stations, each including at least an impregnation station and a curing station. The impregnation station is equipped with a tube clamp and an adhesive coating tank. The clamp holds a pre-fabricated TPU outer tube pre-installed with a spring layer and a metal braided layer, and the tube lumen is coated with adhesive via a lifting mechanism in conjunction with the adhesive coating tank. The equipment is equipped with a vacuum-positive pressure switching device, used for negative pressure suction of TPU adhesive to the inner wall of the tube and positive pressure purging to remove excess adhesive. The curing station is equipped with a curing device for rapid cross-linking and curing. This invention can efficiently fabricate composite medical tubes with stable structures and uniform adhesive layers, suitable for precision medical devices such as endoscopic cannulas.

Description

Technical Field

[0001] This invention relates to the field of medical tube forming equipment, and particularly to a preparation equipment and method for a multilayer composite medical tube. Background Technology

[0002] With the continuous development of medical endoscopy technology, the insertion tubes of gastrointestinal endoscopes not only need to possess good flexibility and bending resistance, but also need to meet high tensile and torque resistance requirements. Current gastrointestinal endoscope insertion tubes generally adopt a three-layer composite structure, including an inner liner, a middle braided metal wire layer, and an outer sheath. The inner liner is usually extruded from polytetrafluoroethylene (PTFE) or other low-friction plastics, with a smooth inner wall to ensure smooth passage of instruments and gas / liquid channels. The middle braided metal wire layer is formed by braiding / spiral winding of stainless steel or nickel-titanium alloy wire around the inner liner, creating a mesh or spiral structure that closely adheres to the liner, improving the accuracy of torque transmission and overall tensile strength. The outer sheath is covered with polyurethane (TPU) or other wear-resistant and chemically resistant materials, providing a smooth outer surface and enhancing wear resistance and sterilization resistance.

[0003] To meet more stringent mechanical performance requirements, a novel composite tube structure is proposed. The tube body comprises, from the inside out, an inner spring layer, a middle braided metal wire layer, and an outer TPU sheath layer. The inner spring layer uses a continuous stainless steel helical spring to enhance the axial elastic recovery force and compressive strength of the tube body. The middle braided metal wire layer is tightly wound around the adhesive layer, responsible for circumferential strength and torque transmission. The outer TPU sheath layer ensures a smooth and uniform surface and provides wear-resistant and chemical corrosion-resistant protection. The inner wall of the inner spring layer is impregnated with TPU adhesive, and the two metal layers are bonded to the outer TPU sheath layer through impregnation or co-extrusion processes. However, existing three-layer pipe fabrication technologies struggle to integrate the aforementioned double-layer metal structure in a single process. Current common processes suffer from limitations: single-machine extrusion is restricted because plastic extruders can only process thermoplastic polymers and cannot coat the inner spring layer and the intermediate metal wire braided layer; metal wire braiding equipment cannot simultaneously form a composite layer from the inner spring layer and the intermediate metal wire braided layer; and existing single-extrusion technologies cannot fabricate the aforementioned composite pipe structure. Summary of the Invention

[0004] The purpose of this invention is to provide a preparation device for multilayer composite medical tubes, which has the advantages of uniform inner wall coating, high precision control of adhesive layer thickness, and high production efficiency.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A device for preparing multilayer composite medical tubing, comprising: The workbench is equipped with at least an impregnation station and a curing station. The upper part of the glue-dipping station is equipped with a tube clamp, and the lower part is equipped with a glue-coating tank for clamping the pre-made TPU outer tube with a pre-installed inner spring layer and a middle metal wire braided layer. The glue-coating tank is filled with TPU glue. The tube clamp or glue-coating tank is equipped with a lifting mechanism to allow the pre-made TPU outer tube to enter and exit the glue-coating tank. The pre-made TPU outer tube is located between the tube clamp and the glue-coating tank and forms a tube cavity. A vacuum positive pressure switching device is connected at least partly to the tube clamp and communicates with the tube cavity at the glue impregnation station. It is used to draw air from the tube cavity in negative pressure mode to draw TPU glue to the inner wall of the pre-made TPU outer tube, and to introduce gas into the tube cavity in positive pressure mode to scrape off excess glue. The curing station is equipped with a curing device and a moving component for switching to the curing position. The curing device is used to cross-link and cure the tube after it has been coated with adhesive.

[0006] Further configuration: The vacuum positive pressure switching device includes: A vacuum pump is used to draw air from a tube in negative pressure mode. Compressed air source, used to introduce gas into the cavity in positive pressure mode; Solenoid valves are used to switch between vacuum pumps and compressed air sources to achieve switching between negative pressure suction mode and positive pressure purging mode. A pressure sensor, located on the pipe clamp and facing the inside of the pipe cavity, is used to detect the pressure inside the pipe cavity in real time. The first controller is electrically connected to the vacuum pump, compressed air source, solenoid valve and pressure sensor, and is used to control the start and stop of the vacuum pump and compressed air source and the switching of the solenoid valve according to the detected cavity pressure.

[0007] Further configuration: The curing device includes: UV light source; A rod-shaped base is connected to a movable component and driven by the movable component to move up and down relative to the curing station in the vertical direction to adjust the relative position of the UV light source and the prefabricated TPU outer tube.

[0008] Further features include a micro-motion device for micro-vibrating or rotating the pre-fabricated TPU outer tube during negative and positive pressure stages to assist in the self-leveling of the adhesive layer; the micro-motion device includes: A vibrator, mounted on the tube clamp, provides micro-vibration motion to the prefabricated TPU outer tube on the tube clamp; The rotating device is connected to the pipe clamp and is used to drive the pipe clamp to rotate at a constant speed. The second controller is electrically connected to the vibrator and the rotating device, and is used to switch or superimpose the operation modes of the vibrator and the rotating device according to a preset program, so as to apply micro-vibration or rotation to the tube body separately or simultaneously during the negative pressure suction and positive pressure purging stages.

[0009] Further configuration includes: a loading station and a unloading station; the workbench is a ring-shaped workbench, and the loading station, adhesive impregnation station, curing station and unloading station are arranged sequentially on the circumference of the ring-shaped workbench; The drive mechanism is used to rotate the ring-shaped worktable and sequentially transport the prefabricated TPU outer tubes to the next station.

[0010] Further configuration: The tube clamp includes an air passage connected to the vacuum positive pressure switching device and an annular groove adapted to the prefabricated TPU outer tube. The prefabricated TPU outer tube is clamped in the annular groove, and the vacuum positive pressure switching device is connected to the air passage through a rotary joint.

[0011] Further setting: The viscosity of the TPU adhesive is in the range of 5–10 Pa·s.

[0012] Another object of the present invention is to provide a method for preparing a device using the aforementioned multilayer composite medical tube, comprising the following steps: S1, Material Loading Positioning S11. Place the pre-fabricated TPU outer tube with pre-installed stainless steel spring and intermediate metal wire braided layer into the glue-impregnation station fixture on the workbench. S12. Adjust the axis of the prefabricated TPU outer tube to be coaxial with the center of the adhesive coating tank and keep it fixed. S2, Negative pressure suction coating S21. Descend the tube clamp or raise the glue coating tank so that the prefabricated TPU outer tube is immersed in the glue coating tank. S22. Start the vacuum pump and use the solenoid valve to draw the pressure in the tube to 20–50 mbar. S23. Maintain this negative pressure for 10–20 seconds, allowing the TPU adhesive with a viscosity of 5–10 Pa·s to climb up the inner wall to the top of the tube. S3, Positive pressure blowing and scraping film S31. Ascend the tube body clamp or descend the glue coating tank to allow the pre-fabricated TPU outer tube to leave the glue coating tank. S32. Switch to compressed air source and introduce 5–10 mbar positive pressure into the pipeline through the solenoid valve. Maintain for 5–10 seconds to scrape off excess adhesive. S4, UV curing S41. The workbench moves the tube to the curing station, and the moving component extends the curing device into the curing position inside the tube. S42. Start the UV light source irradiation for 10–30s. The wavelength of the UV light source is 365–405nm and the irradiation intensity is 10–50mW / cm². S43. After curing, remove the pre-made TPU outer tube from the curing position; S5, unloading.

[0013] Further configuration: In step S2, step S24 is also included: synchronously start the micro-motion device to apply ±1–2mm, 0.5–2Hz axial micro-vibration or 1–5rpm rotation to the prefabricated TPU outer tube.

[0014] In summary, the present invention has the following beneficial effects: First, traditional three-layer extrusion + online braiding processes cannot simultaneously coat the inner spring layer and the middle metal wire braided layer into the same tube body in one go. This device, however, uses vacuum to fully absorb TPU adhesive along the inner wall of the tube at the adhesive impregnation station, then quickly switches to positive pressure "air knife" mode to scrape off excess adhesive, forming a single-layer uniform film through pressure difference and capillary force. This efficiently and reliably laminates the inner spring layer and the middle metal wire braided layer onto the inner wall of the prefabricated TPU outer tube, avoiding the problems of weak adhesion and interface weakening caused by multi-segment splicing or discrete bonding.

[0015] Secondly, the solution in this invention precisely utilizes the timing, pressure, and rheological properties of negative pressure suction and positive pressure film scraping to not only ensure full cavity wetting but also automatically and quantitatively leave a controllable film thickness, overcoming the difficulty of conventional air knife or dip coating in narrow cavities. During the negative pressure suction stage, the TPU adhesive is forcibly penetrated into the micron-level gaps between the inner spring layer and the intermediate metal wire braided layer, and then cured after positive pressure "air knife" film scraping. The resulting film not only adheres chemically but also forms a mechanical interlock with the metal layer. Traditional processes rely solely on surface coating and extrusion, making it difficult to achieve such deep TPU adhesive filling and interlocking, thus significantly improving interlayer bonding strength and fatigue life.

[0016] Third, in this invention, axial micro-vibration of ±1–2 mm or slow rotation of 1–5 rpm is superimposed during the negative and positive pressure stages. Shearing and centrifugal forces are used to eliminate air bubbles and level the adhesive film, allowing the semi-fluid adhesive to self-level immediately after millisecond-level pressure switching, thus eliminating tiny air bubbles. This process achieves highly efficient defect removal within the narrow lumen of an endoscope, a capability difficult to achieve with conventional air knife or vibration processes on open surfaces.

[0017] Fourth, the circular worktable and multi-station linkage form a closed loop from material feeding → negative pressure coating → positive pressure film scraping → UV curing → material unloading, which can realize assembly line production and reduce manual intervention; with the help of lifting mechanism, moving components and curing device, the preparation cycle of a single tube can be shortened and the production capacity can be greatly improved.

[0018] Fifth, in this invention, TPU adhesive viscosity, surface tension, positive pressure difference, pipe diameter and contact angle are explicitly incorporated into a unified formula to guide parameter selection and thickness control, and are used for real-time parameter calibration and process stability assurance, breaking through the limitations of experience-based parameter adjustment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the equipment for preparing multilayer composite medical tubes; Figure 2 This is a structural diagram of the workbench; Figure 3 This is a structural schematic diagram of the pipe clamp; Figure 4 This is a structural schematic diagram of the glue coating tank and curing device; Figure 5 This is a schematic diagram of a vacuum positive pressure switching device.

[0020] In the diagram, 10 is the prefabricated TPU outer tube; 100. Workbench; 101. Loading station; 102. Dipping station; 103. Curing station; 104. Unloading station; 105. Drive mechanism; 106. Lifting mechanism; 200. Pipe clamp; 201. Air passage; 202. Annular groove; 203. Rotary joint; 300. Glue application tank; 400. Vacuum positive pressure switching device; 401. Vacuum pump; 402. Compressed air source; 403. Solenoid valve; 404. Pressure sensor; 405. First controller; 500. Curing device; 501. Moving component; 502. Rod-shaped base; 503. UV light source; 600. Micro-motion device; 601. Vibrator; 602. Rotation device; 603. Second controller. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] This invention provides a device for preparing multilayer composite medical tubes, such as... Figure 1 and Figure 2As shown, the device includes a worktable 100 and a drive mechanism 105 that works in conjunction with it. The worktable 100 is circular and horizontally arranged, and can rotate around its central axis. The worktable 100 is provided with at least an impregnation station 102 and a curing station 103. The drive mechanism 105 is located below the worktable 100 and is mechanically connected to it, and is used to rotate the worktable 100 at a constant speed in a clockwise or counterclockwise direction, thereby conveying the prefabricated TPU outer tube 10 to each functional station in sequence.

[0024] The specific structural form of the drive mechanism 105 is not limited. In this embodiment, the drive mechanism 105 can be one or a combination of a stepper motor, servo motor, cylinder drive device, chain drive device or cam divider, etc. The drive mechanism 105 is connected to the rotation shaft of the worktable 100 and is arranged below the worktable 100. It can drive the worktable 100 intermittently or continuously, thereby realizing the orderly conversion of work stations and the gradual processing of the tube.

[0025] In this embodiment, the workbench 100 is a ring-shaped workbench 100, and the impregnation station 102 and the curing station 103 are arranged sequentially on the circumference of the ring-shaped workbench 100; this embodiment also includes a loading station 101 and a unloading station 104; specifically, the loading station 101, the impregnation station 102, the curing station 103 and the unloading station 104 are arranged sequentially on the circumference of the ring-shaped workbench 100. The loading station 101 is connected to the feeding end of the workbench 100 and is used to introduce the pre-made TPU outer tube 10 to be processed; the dipping station 102 is set in the clockwise direction of the loading station 101 and is used to immerse the tube into the adhesive; the curing station 103 is located in the clockwise direction of the dipping station 102 and is used to cure the pre-made TPU outer tube 10 after dipping; the unloading station 104 is arranged in the clockwise direction of the curing station 103 and is used to receive the finished pre-made TPU outer tube 10 after curing and transport it to the next process.

[0026] At the impregnation station 102, a tube clamp 200 is provided at the top and an adhesive coating tank 300 is provided at the bottom. The tube clamp 200 and the adhesive coating tank 300 are arranged opposite each other, spaced apart in the vertical direction, and together they form a working space for installing the prefabricated TPU outer tube 10 to be processed. Specifically, the prefabricated TPU outer tube 10 is placed between the tube clamp 200 and the adhesive coating tank 300 and forms a cavity. The tube clamp 200 is used to clamp the prefabricated TPU outer tube 10 with the pre-installed inner spring layer and the intermediate metal wire braided layer to ensure its stability and coaxiality during the impregnation process. The adhesive coating tank 300 is used to hold TPU adhesive with a viscosity controlled within a certain range and is set perpendicular to the axial direction of the prefabricated TPU outer tube 10, so that the prefabricated TPU outer tube 10 can be inserted vertically into the adhesive coating tank 300 or removed from the adhesive coating tank 300 under the drive of the tube clamp 200.

[0027] To achieve the aforementioned insertion and removal actions, at least one of the tube clamp 200 or the adhesive coating tank 300 is equipped with a lifting mechanism 106 to drive the tube or adhesive coating tank 300 to move vertically, thereby enabling the prefabricated TPU outer tube 10 to switch between entry and exit at different stages. During processing, the prefabricated TPU outer tube 10 is inserted into the adhesive coating tank 300 under the positioning of the tube clamp 200. The tube clamp 200 and the adhesive coating tank 300 surround and form a closed tube cavity space, providing an operating environment for subsequent suction. In this embodiment, reference is made to... Figure 4 The lifting mechanism 106 is preferably located on one side of the glue coating tank 300, and is suitable for driving the glue coating tank 300 to rise and fall.

[0028] The specific structural form of the lifting mechanism 106 is not limited. In this embodiment, the lifting mechanism 106 can be in the form of an electric push rod, a pneumatic cylinder, a slide rail slider assembly or a servo lifting device, etc. The lifting mechanism 106 is connected to the bearing structure of the tube clamp 200 or the glue application tank 300 and is arranged on the upper or outer side of the workbench 100.

[0029] refer to Figure 3 The specific structure of the tube clamp 200 is not limited. In this embodiment, the tube clamp 200 includes an air passage 201 connected to the vacuum positive pressure switching device 400, and an annular groove 202 structure that matches the size of the prefabricated TPU outer tube 10. The prefabricated TPU outer tube 10 can be tightly clamped in the annular groove 202 to ensure the stability of the tube's position during the coating and suction processes. The vacuum positive pressure switching device 400 is rotatably connected to the air passage 201 through a rotary joint 203 located on one side of the tube clamp 200.

[0030] refer to Figure 1 , Figure 3 and Figure 4 A vacuum positive pressure switching device 400 is further provided at the adhesive dipping station 102. The vacuum positive pressure switching device 400 is connected to at least a part of the structure set on the tube clamp 200. Specifically, it is connected to the cavity formed by the tube clamp 200 and the coating tank 300 through a rotary joint 203. The vacuum positive pressure switching device 400 is used to control the air pressure inside the cavity. Specifically, in the negative pressure working mode, air is sucked out of the cavity to create a low-pressure state inside the cavity, so as to cause the TPU adhesive in the coating tank 300 to climb along the inner wall of the pre-made TPU outer tube 10, thereby forming an adhesive layer. In the positive pressure working mode, gas is introduced into the cavity to increase the air pressure inside the cavity, thereby using the airflow to scrape off the excess adhesive on the inner wall of the pre-made TPU outer tube 10, so as to control the coating thickness and uniformity.

[0031] Specifically, one end of the tube is sealed to the coating tank 300, and the other end is connected to the vacuum pump 401. The pumping rate is controlled at 1–2 L / min, with a target vacuum of 20–50 mbar. This allows the TPU adhesive to rise to the top of the tube within tens of milliseconds to several seconds, forming a clear liquid-gas interface with the portion not submerged in the adhesive. Once the TPU adhesive has filled the tube, a relatively stable liquid-gas interface is automatically established, and the tube is in a "full liquid state." The pressure is then rapidly (<100 ms) switched from negative to a small positive pressure (5–10 mbar). This positive pressure pushes the TPU adhesive in the tube back down to the coating tank 300, effectively performing a weak "air knife" scraping on the inner wall of the tube. The switch from negative to positive pressure is completed in milliseconds, preventing the TPU adhesive from accumulating in large clumps in the center of the cavity; it is scraped back almost simultaneously by the "air knife." The adhesion between the TPU adhesive and the TPU tube wall is higher than the TPU adhesive's own gravity and centrifugal force, ensuring a thin adhesive film remains stably on the wall surface. In this embodiment, the viscosity of the TPU adhesive is in the range of 5–10 Pa·s. Different viscosities are selected based on the required wall thickness and molding conditions.

[0032] Furthermore, the amount of TPU adhesive residue on the tube wall depends on the magnitude of the positive pressure, viscosity (η), tube wall surface energy, and the mechanical balance of the adhesive-gas-wall three-phase contact line. The vacuum positive pressure switching device 400, the TPU adhesive used, and the inner wall surface of the prefabricated TPU outer tube 10 satisfy the following comprehensive relationship, ensuring that the thickness h of the residual adhesive layer on the inner wall of the tube is within a controllable range: in: : Thickness of residual adhesive layer on the inner wall of the pipe; Inner radius of the pipe; TPU adhesive viscosity; TPU adhesive - gas interfacial tension; : Pressure difference between the inside and outside of the tube during positive pressure scraping; Air density; : Static contact angle of TPU adhesive on the pipe wall.

[0033] In this embodiment, to more intuitively illustrate the meaning of the formula and its application, a specific calculation example is given below.

[0034] Take the inner radius of the pipe ; The viscosity of the selected TPU adhesive cdotps; TPU adhesive - gas interfacial tension ; Pressure differential applied during the positive pressure scraping stage (Approximately 5 mbar); air density ; Contact angle .

[0035] First, calculate the Capri number terms: Then take it Power: Next, calculate the contact angle correction term: Finally, substitute And a pre-factor of 0.94: Therefore, under the above parameter conditions, the thickness h of the residual adhesive layer on the inner wall of the tube is approximately 0.23 mm. This example illustrates that by appropriately selecting parameters such as pressure difference, TPU adhesive viscosity, interfacial tension, and contact angle, the adhesive coating thickness can be accurately predicted and controlled using this formula.

[0036] Further reference Figure 2 and Figure 4 The curing station 103 is equipped with a curing device 500 and a moving component 501 for driving the curing device 500 to switch to the curing position. The curing device 500 is mounted on the moving component 501 and can move vertically or in the desired direction under the drive of the moving component 501 to position the curing device 500 to the curing position corresponding to the tube body after adhesive coating. The curing device 500 is used to perform cross-linking curing treatment on the tube body after adhesive coating, so that the TPU adhesive attached to the inner wall of the prefabricated TPU outer tube 10 completes the cross-linking reaction in a short time and forms a stable adhesive film, thereby finally completing the structure of the medical tube.

[0037] The structural form of the moving component 501 is not specifically limited. Various driving methods and structural forms can be selected according to actual application requirements to achieve the vertical movement of the curing device 500 relative to the pre-fabricated TPU outer tube 10. In this embodiment, the moving component 501 can be an electric push rod, a pneumatic cylinder, a slide rail slider assembly, or a servo lifting mechanism 106, etc. The moving component 501 is installed above or to the side of the curing station 103 and connected to the rod-shaped base 502 of the curing device 500. It can drive the curing device 500 to move vertically or in a direction corresponding to the axis of the pre-fabricated TPU outer tube 10, so as to precisely adjust the relative position between the UV light source 503 and the pre-fabricated TPU outer tube 10, thereby achieving effective irradiation and curing of the adhesive layer inside the tube cavity.

[0038] Based on the above embodiments, as a further limiting embodiment, such as... Figure 5 As shown, the vacuum-positive-pressure switching device 400 includes a vacuum pump 401, a compressed air source 402, a solenoid valve 403, a pressure sensor 404, and a first controller 405. The vacuum pump 401 is used to suction the interior of the tube cavity positioned between the tube clamps 200 in negative pressure mode, thereby expelling air from the cavity and allowing TPU adhesive to be adsorbed onto the inner wall of the prefabricated TPU outer tube 10 under negative pressure. The compressed air source 402 is used to introduce gas into the cavity in positive pressure mode to scrape away excess adhesive on the inner wall, thereby forming a uniform adhesive layer. The solenoid valve 403 is positioned between the vacuum pump 401 and the compressed air source 402, used to switch between them, thereby enabling switching between negative pressure suction mode and positive pressure purging mode. The pressure sensor 404 is mounted on the tube clamps 200, facing the interior of the cavity, and is used to collect pressure data within the cavity in real time. The first controller 405 is electrically connected to the vacuum pump 401, the compressed air source 402, the solenoid valve 403, and the pressure sensor 404 respectively. It is used to receive feedback signals from the pressure sensor 404 and automatically control the start and stop states of the vacuum pump 401 and the compressed air source 402 according to the detected pressure inside the cavity. At the same time, it controls the on and off switching of the solenoid valve 403 to achieve precise adjustment and automatic switching of the pressure inside the cavity.

[0039] Based on the above embodiments, as a further limiting embodiment, such as... Figure 4 As shown, the curing device 500 includes a UV light source 503 and a rod-shaped base 502 connected to a moving member 501. The rod-shaped base 502 has a longitudinally extending structure, with one end fixedly connected to the moving member 501 and driven by the moving member 501 to move vertically relative to the curing station 103, thereby adjusting the vertical position between the UV light source 503 and the pre-made TPU outer tube 10 to be cured. This ensures that the curing light source maintains a suitable irradiation distance from the adhesive layer surface, which is beneficial for the uniform cross-linking and curing of the adhesive layer.

[0040] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the equipment also includes a micro-motion device 600, which is set at the adhesive impregnation station 102. It is used to apply micro-vibration or rotational motion to the prefabricated TPU outer tube 10 during the negative pressure suction stage and the positive pressure purging stage to assist the self-leveling and uniform distribution of the adhesive in the tube cavity, thereby improving the coating quality.

[0041] The micro-motion device 600 includes a vibrator 601 mounted on the tube clamp 200, which drives the prefabricated TPU outer tube 10 clamped on the tube clamp 200 to generate axial or radial micro-vibrations; it also includes a rotating device 602, which is connected to the tube clamp 200 and drives the tube clamp 200 to rotate around its axis at a constant speed. The micro-motion device 600 further includes a second controller 603, which is electrically connected to the vibrator 601 and the rotating device 602 respectively, and controls the start-stop and movement state of the vibrator 601 and the rotating device 602 according to a preset program, applying micro-vibration and rotation actions separately or simultaneously in negative pressure mode and positive pressure mode, thereby optimizing the uniformity of TPU adhesive distribution and adhesion consistency on the inner wall of the prefabricated TPU outer tube 10. Specifically, axial micro-vibration of ±1–2 mm or slow rotation of 1–5 rpm is superimposed during the negative and positive pressure stages to eliminate air bubbles and level the film using shear and centrifugal forces. The superposition mechanism of micro-vibration and rotation has an extremely complex effect on fluid behavior. This scheme precisely matches the amplitude, frequency, and rotation speed to achieve flow self-leveling and air bubble removal in an extremely narrow space, which is difficult to predict in conventional processes.

[0042] The present invention also provides a method for preparing the above-mentioned multilayer composite medical tube preparation device, comprising the following steps: Step S1: Loading and positioning.

[0043] S11, the prefabricated TPU outer tube 10 with pre-installed stainless steel spring layer and intermediate metal wire braid layer is placed in the tube clamp 200 set on the glue dipping station 102 of the workbench 100. S12, by adjusting the lifting mechanism 106 or the auxiliary positioning structure, the axis of the prefabricated TPU outer tube 10 is aligned coaxially with the central axis of the glue coating tank 300 located below, and is kept stable and fixed in this position to ensure coaxiality and uniformity in the subsequent glue coating process.

[0044] Step S2: Apply adhesive using negative pressure suction.

[0045] S21, by driving the lifting mechanism 106, the tube clamp 200 is lowered or the glue coating tank 300 is raised, so that the prefabricated TPU outer tube 10 is gradually immersed into the glue coating tank 300 until the set immersion depth is reached. S22, start vacuum pump 401, switch control through solenoid valve 403 to make the pressure inside the tube be drawn to a negative pressure state of 20-50mbar. S23, maintain the negative pressure state for 10–20 seconds to allow the TPU adhesive with a viscosity of 5–10 Pa·s to climb up along the inner wall of the tube and evenly coat the inner surface of the tube cavity. Step S3: Positive pressure purging and scraping film.

[0046] S31, the lifting mechanism 106 controls the tube clamp 200 to rise or the glue tank 300 to fall, so that the pre-made TPU outer tube 10 is completely separated from the glue tank 300, avoiding excessive glue from continuing to adhere. S32, the solenoid valve 403 switches to the compressed air source 402 passage, and introduces 5-10 mbar of positive pressure gas into the cavity for 5-10 seconds, so that the residual adhesive is evenly scraped or blown into a thin layer, further controlling the thickness of the inner coating and improving the surface quality.

[0047] Step S4: UV curing.

[0048] S41, the drive mechanism 105 drives the worktable 100 to rotate, and transports the pre-made TPU outer tube 10 with the adhesive applied to the curing station 103 located at the next position. The moving component 501 drives the curing device 500 to extend vertically into the curing area inside the tube cavity. S42, start the UV light source 503 and irradiate according to the set parameters. The irradiation time is 10-30 seconds, the wavelength of the UV light source 503 is 365-405nm, and the irradiation intensity is 10-50mW / cm², so as to promote the full cross-linking and curing of the inner wall adhesive layer. S43, after curing is completed, the UV light source 503 is moved to the standby position by moving component 501, and the prefabricated TPU outer tube 10 is moved out from the curing station 103 to prepare for the next process.

[0049] Step S5: Unloading.

[0050] Once the pre-cured TPU outer tube 10 has been cured, it is automatically or manually removed from the unloading station 104, completing one molding cycle and awaiting subsequent testing or processing.

[0051] Based on the above implementation method, as a further defined implementation method, step S2 also includes step S24: during the above negative pressure suction process, the micro-motion device 600 is activated to apply axial micro-vibration of ±1–2 mm and 0.5–2 Hz to the prefabricated TPU outer tube 10, or to rotate slowly at a speed of 1–5 rpm, so as to promote the self-leveling, adhesion and diffusion of the adhesive on the inner wall of the tube cavity, thereby further improving the uniformity of the inner adhesive film.

[0052] The above embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An apparatus for producing a multilayer composite medical tube, characterized by comprising: include: The workbench (100) is provided with at least an impregnation station (102) and a curing station (103); The upper part of the dipping station (102) is provided with a tube clamp (200) and the lower part is provided with a glue coating tank (300) for clamping the prefabricated TPU outer tube (10) with a pre-installed inner spring layer and a middle metal wire braided layer. The glue coating tank (300) is filled with TPU glue. The tube clamp (200) or the glue coating tank (300) is provided with a lifting mechanism (106) so that the prefabricated TPU outer tube (10) can enter and exit the glue coating tank (300). The prefabricated TPU outer tube (10) is located between the tube clamp (200) and the glue coating tank (300) and forms a tube cavity. The vacuum positive pressure switching device (400) is located at least partly on the tube clamp (200) and is connected to the tube cavity at the glue impregnation station (102). It is used to draw air from the tube cavity in negative pressure mode to draw TPU glue to the inner wall of the pre-made TPU outer tube (10), and to introduce gas into the tube cavity in positive pressure mode to scrape off excess glue. The curing station (103) is equipped with a curing device (500) and a moving component (501) for switching to the curing position. The curing device (500) is used to crosslink and cure the tube after it has been coated with adhesive. The vacuum positive pressure switching device (400) includes: A vacuum pump (401) is used to draw air from the cavity in negative pressure mode; Compressed gas source (402) is used to introduce gas into the cavity in positive pressure mode; Solenoid valve (403) is used to switch between vacuum pump (401) and compressed gas source (402) to achieve switching between negative pressure suction mode and positive pressure purging mode; A pressure sensor (404) is located on the pipe clamp (200) and facing into the pipe cavity, for real-time detection of the pressure inside the pipe cavity; The first controller (405) is electrically connected to the vacuum pump (401), compressed air source (402), solenoid valve (403) and pressure sensor (404), and is used to control the start and stop of the vacuum pump (401) and compressed air source (402) and the switching of solenoid valve (403) according to the detected cavity pressure.

2. The equipment for preparing multilayer composite medical tubes according to claim 1, characterized in that: The curing device (500) includes: UV light source (503); A rod-shaped base (502) is connected to a movable component (501) and is driven by the movable component (501) to move up and down relative to the curing station (103) in the vertical direction to adjust the relative position of the UV light source (503) and the prefabricated TPU outer tube (10).

3. The equipment for preparing multilayer composite medical tubes according to claim 1, characterized in that: Also includes: Loading station (101), unloading station (104); the workbench (100) is a ring workbench (100), and the loading station (101), the glue-impregnation station (102), the curing station (103) and the unloading station (104) are arranged sequentially on the circumference of the ring workbench (100); The drive mechanism (105) is used to drive the ring worktable (100) to rotate and sequentially transport the prefabricated TPU outer tube (10) to the next station.

4. The equipment for preparing multilayer composite medical tubes according to claim 1, characterized in that: The tube clamp (200) includes an air passage (201) connected to the vacuum positive pressure switching device (400) and an annular groove (202) adapted to the prefabricated TPU outer tube (10). The prefabricated TPU outer tube (10) is clamped in the annular groove (202). The vacuum positive pressure switching device (400) is connected to the air passage (201) through a rotary joint (203).

5. The equipment for preparing multilayer composite medical tubes according to claim 1, characterized in that: The viscosity of the TPU adhesive is in the range of 5–10 Pa·s.

6. A method for preparing multilayer composite medical tubes using the equipment described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1, Material Loading Positioning S11. Place the pre-fabricated TPU outer tube (10) with pre-installed stainless steel spring and intermediate metal wire braided layer into the glue-impregnation station (102) fixture of the workbench (100); S12. By adjustment, make the axis of the prefabricated TPU outer tube (10) coaxial with the center of the glue coating tank (300) and keep it fixed; S2, Negative pressure suction coating S21, a descending tube clamp (200) or an ascending adhesive tank (300) is used to immerse the pre-fabricated TPU outer tube (10) into the adhesive tank (300); S22. Start the vacuum pump (401) and pump the pressure in the tube to 20–50 mbar through the solenoid valve (403); S23. Maintain this negative pressure for 10–20 seconds, allowing the TPU adhesive with a viscosity of 5–10 Pa·s to climb up the inner wall to the top of the tube. S3, Positive pressure blowing and scraping film S31, rise tube body clamp (200) or descend glue tank (300) to allow the pre-made TPU outer tube (10) to leave the glue tank (300); S32. Switch to compressed air source (402) and introduce 5-10 mbar positive pressure into the pipeline through solenoid valve (403) and maintain for 5-10 seconds to scrape off excess adhesive. S4, UV curing S41, The workbench (100) moves the tube to the curing station (103), and the moving component (501) extends the curing device (500) into the curing position inside the prefabricated TPU outer tube (10). S42. Start the UV light source (503) for 10–30s. The wavelength of the UV light source (503) is 365–405nm and the irradiation intensity is 10–50mW / cm². S43. After curing, remove the prefabricated TPU outer tube (10) from the curing position; S5, unloading.

7. The preparation method according to claim 6, characterized in that: Step S2 also includes step S24: synchronously start the micro-motion device (600) to apply ±1–2 mm, 0.5–2 Hz axial micro-vibration or 1–5 rpm rotation to the prefabricated TPU outer tube (10).

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