Polymeric medical catheter tube and method of forming and connecting same

Abstract

The application relates to the medical field, in particular to a high-molecular medical catheter pipe fitting and a forming method and a connecting method thereof. The forming method of the high-molecular medical catheter pipe fitting is characterized by comprising the following steps: step 1, an etching pipe is penetrated into the initial end of the lumen of an outer cavity pipe and stretched out from the tail end of the lumen of the outer cavity pipe; step 2, the tail end of the etching pipe is made to have a smaller diameter than the initial end of the etching pipe; and step 3, a fluid is filled into the lumen of the etching pipe from the initial end of the etching pipe, the fluid can at least expand the lumen of the etching pipe to make the outer wall of the etching pipe adhere to the inner wall of the outer cavity pipe, and the fluid can make the temperature of each joint be kept between 130 DEG C and 210 DEG C, so that the inner wall of the outer cavity pipe is fused to the outer wall of the etching pipe. The scheme adopts the scheme of fluid expansion inner support and inner heating, so that a high-precision core rod does not need to be penetrated into the lumen of the etching pipe, the related processes of winding and pulling off the heat-shrinkable tube are omitted, the technological process is simplified, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the medical field, and more particularly to a polymer medical catheter fitting and its molding and connection methods. Background Technology

[0002] In medicine, to perform certain diagnostic and treatment procedures, such as endoscopic examination of the digestive tract, it is necessary to establish channels inside and outside the body cavities. This can be achieved by inserting a medical catheter into the body cavity and then delivering the necessary tools or substances through the catheter. On the one hand, to prevent unnecessary damage to the body cavity during catheter movement, the outer wall of the catheter should obviously be kept as smooth as possible, ensuring that the surface quality of the outer wall meets certain standards. On the other hand, to ensure that the necessary tools or substances can smoothly pass through the medical catheter and reach their target location within the body cavity, the surface quality of the inner wall of the catheter must also meet certain requirements. However, for various reasons, medical catheters may be made of materials of different specifications or materials connected axially (or along the length) of the catheter. This connection must consider not only the surface quality of the outer wall at the connection point, for the reasons mentioned above, but also the surface quality of the inner wall at the connection point to ensure the passage within the lumen at the connection point. In addition, the aforementioned medical catheters extensively utilize polymer materials, commonly including polyurethane, silicone rubber, polyester fiber, polyvinylpyrrolidone, polyetheretherketone, polymethyl methacrylate, polyvinyl alcohol, polylactic acid, and polyethylene.

[0003] Ensuring the quality of both the internal and external surfaces of the joint while reducing processing costs is a challenge currently facing the industry. Summary of the Invention

[0004] When connecting polymer medical catheters of different specifications or materials, a built-in PTFE etched tube can be used.

[0005] PTFE is the abbreviation for polytetrafluoroethylene, a high molecular polymer obtained by polymerizing tetrafluoroethylene as a monomer. Its characteristics include high lubricity, having the lowest coefficient of friction among solid materials; non-adhesion, having the lowest surface tension among solid materials, and not adhering to any substance; non-toxicity, and physiological inertness, so it has no adverse reactions when used as artificial blood vessels and organs for long-term implantation in the body.

[0006] However, the difficulty in bonding PTFE limits its application in some fields. Researchers have proposed a chemical treatment method for the surface of polytetrafluoroethylene (PTFE) pipes, which mainly involves a chemical reaction between an etching solution and the PTFE film surface to remove some of the fluorine atoms. This leaves a carbonized layer and certain polar groups on the surface. The portion with the fluorine atoms removed has better adhesion properties, which is the so-called PTFE etched pipe (the etched pipe mentioned below in this application refers to PTFE etched pipes).

[0007] Taking the connection of PTFE etched tubing to PEBAX medical catheter tubing as an example, the connection method is as follows:

[0008] Step 1: Insert a high-precision mandrel (or spindle) into the etched tube. The mandrel and the inner wall of the etched tube cavity can be or nearly interference fit.

[0009] Step 2: Insert both ends of the etched tube with built-in mandrel into the two tubes to be connected on both sides, with the etched tube located at the connection point of the two tubes.

[0010] Step 3: Wrap a layer of FEP heat shrink tubing around the outside of the connection point;

[0011] Step 4: Place the connector inside the rheometer and heat the tube connection part (microwave heating, baking, or hot air blowing) to shrink the outer FEP heat shrink tube.

[0012] Step 5: After the outer wall of the etched tube is firmly bonded to the inner walls of the two tubes, remove the mandrel and the FEP heat shrink tubing to form a composite tube. This composite tube forms a two-layer tube structure at the connection point. The inner layer is a PTFE tube, and the outer walls of both ends of the PTFE tube are bonded to the inner walls of the tubes being connected, with the walls of the tubes being connected forming the outer layer.

[0013] In the above method, it is crucial to ensure that the rigid mandrel can be inserted into the cavity of the rigid etched tube before implementation, and also to meet the design requirements for the cavity size of the etched tube after implementation (the external specifications of the mandrel determine the internal specifications of the etched tube after the process). This places extremely high demands on the dimensional accuracy of the mandrel; otherwise, if the mandrel is too large, it cannot be inserted, and if it is too small, wrinkles will form in the etched tube during heat shrinking (excessive accumulation of the etched tube relative to the mandrel), leading to poor internal permeability. Furthermore, the precision requirements for the connected cavities are also very high; otherwise, the etched tube lined with the mandrel cannot be both easily inserted and have the required cavity size guaranteed after heat shrinking.

[0014] Even more challenging is that when the above process is applied to the connection of multi-cavity tubes, the dimensions of the multi-cavity tubes are often different, and the corresponding mandrel sizes are also different. In addition to the precision issues mentioned above, there is also the need to pass multiple mandrels through multiple cavities in a corresponding manner, and multiple mandrels need to correspond one-to-one with multiple cavities, which will increase the difficulty of material management and production.

[0015] To address the aforementioned problems, the primary objective of this invention is to provide a molding method for polymer medical catheter fittings. This method abandons the existing scheme of mandrel internal support and heat shrink tubing external limiting, and instead adopts a scheme of fluid expansion internal support and internal heating. This eliminates the need to insert a high-precision mandrel into the etched tube cavity, saves the related processes of winding and removing heat shrink tubing, simplifies the process, and reduces costs.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] A method for molding polymer medical catheter fittings, characterized by comprising the following steps:

[0018] Step 1: Insert the etched tube into the lumen of the outer tube from the beginning of the lumen and extend it from the end of the lumen of the outer tube.

[0019] Step 2: Make the diameter of the tail end of the etched tube smaller than the diameter of the starting end of the etched tube;

[0020] Step 3: Fluid is injected into the cavity of the etching tube from the beginning of the tube. The fluid is sufficient to expand the cavity of the etching tube so that the outer wall of the etching tube fits against the inner wall of the outer cavity tube. The fluid keeps the temperature at each joint between 130°C and 210°C, so that the inner wall of the outer cavity tube melts and combines with the outer wall of the etching tube.

[0021] The present invention adopts the above-mentioned technical solution, which relates to a molding method for polymer medical catheter fittings. The molding method of the polymer medical catheter fittings has the following similarity with the prior art: both have an etched tube fixed inside the outer lumen tube. The setting of the etched tube can achieve the following effects: the smoothness requirement of the catheter fitting is high, so that the guide wire or other instruments inserted into the catheter can be inserted more smoothly; it can be applied to the connection between multiple catheter fittings.

[0022] Based on this, this solution differs from existing technologies and offers the following innovations:

[0023] This solution abandons the existing mandrel-supported approach and instead adopts a fluid expansion-supported approach. This eliminates the need to insert a high-precision mandrel into the etched tube cavity, reducing processing requirements and eliminating the step of inserting the mandrel into the etched tube cavity using an interference fit, thus improving processing efficiency. Furthermore, it avoids the problem of insufficient mandrel precision or roundness preventing tube insertion.

[0024] This solution eliminates the need for external heat shrink tubing and the placement of the conduit within the rheometer. Instead, fluid is introduced into the etched tube cavity, and the heat from the fluid melts the inner wall of the outer cavity, bonding it to the outer wall of the etched tube. This solution avoids the processes of wrapping and removing heat shrink tubing, simplifying the process and reducing costs.

[0025] It should be noted that this method requires the fluid to flow inside the cavity of the etching tube. Therefore, the diameter of the tail end of the etching tube is smaller than the diameter of the starting end. This ensures that the inflow velocity of the fluid is greater than the outflow velocity, allowing the fluid to accumulate within the cavity of the etching tube. This, in turn, expands the cavity of the etching tube, causing the outer wall of the etching tube to adhere to the inner wall of the outer cavity.

[0026] Preferably, the etching tube in step 1 is equipped with a rigid support. In a specific implementation, a thin mandrel is lined inside the cavity of the etching tube in step 1, and the outer diameter of the thin mandrel is smaller than the inner diameter of the etching tube cavity. The thin mandrel in this solution differs from the mandrel used in the prior art; it is a rigid support component designed to penetrate the etching tube and provide a certain degree of rigidity, thus facilitating the insertion of the etching tube into the outer cavity. Therefore, the thin mandrel in this solution, on the one hand, has an outer diameter smaller than the inner diameter of the etching tube cavity, and in principle, can be quickly and smoothly inserted into the etching tube while providing sufficient rigidity; on the other hand, it has no requirements for precision or roundness.

[0027] In this scheme, the thin core rod is axially supported or connected to the etching tube, so that the thin core rod and the etching tube are inserted into the cavity of the outer tube together, thus allowing the thin core rod and the etching tube to move axially synchronously.

[0028] In step 1, the rigid support inside the etched tube is removed after the etched tube is inserted.

[0029] In addition, step 4 is included, after fixing, the portions of the etched tube that extend beyond the outer cavity tube are cut off.

[0030] In a further embodiment, in step 1, the outer diameter of the etching tube is larger than the inner diameter of the outer cavity tube, and the etching tube passes through the cavity of the outer cavity tube in a radially contracted state. In other technical solutions besides this application, because the outer cavity tube is also covered with heat-shrink tubing, the inner wall of the outer cavity tube can be made to fit against the outer wall of the etching tube under the tightening force of the heat-shrink tubing. However, this embodiment omits the heat-shrink tubing, relying solely on the expansion of the internal fluid to make the inner wall of the outer cavity tube fit against the outer wall of the etching tube. Moreover, the cavity of the outer cavity tube is not completely closed but rather open-circuited. Under these circumstances, it is difficult to achieve a good bonding effect solely through the expansion of the internal fluid. Therefore, the outer diameter of the etching tube selected in this embodiment is larger than the inner diameter of the outer cavity tube, so that it can fit better against the inner wall of the outer cavity tube in the expanded state. Furthermore, to facilitate the insertion of the etching tube into the outer cavity tube, the etching tube is inserted in a radially contracted state during the insertion process. Here, the end of the etching tube can be sealed, and then the gas inside the etching tube can be evacuated to cause it to contract.

[0031] In a specific implementation, the outer diameter circumference L1 of the etched tube and the inner diameter circumference L2 of the outer cavity tube satisfy the following relationship: L1 is between 105% and 115% of L2. Meeting this ratio requirement allows the etched tube to fit well against the inner wall of the outer cavity tube in its expanded state. On the one hand, the moderately excess portion of the etched tube provides material for the welding between the etched tube and the outer cavity tube; on the other hand, it avoids excessive excess that could lead to wrinkles and unevenness in the etched tube.

[0032] In a further embodiment, in step 2, the diameter of the etched tube tail end is made smaller than the diameter of the etched tube start end; one of the following two methods can be adopted:

[0033] Option 1: The selected etched tube is a variable diameter tube segment whose inner diameter gradually decreases from front to back, and the variable diameter tube segment extends from the end of the outer cavity tube. In this option, the etched tube directly constructs the variable diameter tube segment or connects to the variable diameter tube segment, and the variable diameter tube segment extends from the end of the outer cavity tube, which makes it convenient to cut off the variable diameter tube segment after processing, so as not to affect subsequent use.

[0034] Option 2: The portion of the etched tube extending beyond the outer cavity tube is narrowed to make the diameter of the tail end smaller than the diameter of the starting end. In this option, after the etched tube is inserted into the outer cavity tube, the portion extending beyond the outer cavity tube is narrowed, achieving both diameter reduction and narrowing. After processing, the excess portion is simply cut off.

[0035] Preferably, in step 3, the fluid introduced into the etching tube cavity is a gas, a liquid, or a gas-liquid mixture.

[0036] A second objective of this invention is to provide a method for connecting polymer medical catheter fittings, comprising the following steps:

[0037] Step 1: Insert an etched tube through the first tube and into the second tube. The etched tube is located at the connection between the first tube and the second tube, and the etched tube extends from the tail end of the first tube or the second tube.

[0038] Step 2: Make the diameter of the tail end of the etched tube smaller than the diameter of the starting end of the etched tube;

[0039] Step 3: Fluid is injected into the cavity of the etching tube from the beginning of the tube. The fluid is sufficient to expand the cavity of the etching tube so that the outer wall of the etching tube is in contact with the inner walls of the first and second tubes. The fluid keeps the temperature at each joint between 130°C and 210°C, so that the inner walls of the first and second tubes melt and combine with the outer wall of the etching tube.

[0040] The present invention adopts the above-mentioned technical solution, which relates to a connection method for polymer medical catheter fittings. It is mainly used to connect and fix two or more polymer medical catheters. The connection method is the same as the prior art in that the fittings are still connected by built-in etched tubes. Based on the setting of the etched tubes, on the one hand, a firm connection of the catheter tip fittings can be achieved, and on the other hand, the smoothness of the inner wall at the connection point can be guaranteed.

[0041] Based on this, this solution abandons the existing mandrel internal support method and instead adopts a fluid expansion internal support method. This eliminates the need to insert a high-precision mandrel into the etching tube cavity. On the one hand, it eliminates the need to construct a high-precision mandrel, reducing processing requirements; on the other hand, it also omits the step of inserting the mandrel into the etching tube cavity using an interference fit, improving processing efficiency. Of course, it also avoids the problem of being unable to insert the tube due to insufficient mandrel precision or roundness.

[0042] Furthermore, this solution eliminates the need for external heat shrink tubing and the placement of the conduit within the rheometer. Instead, a fluid is introduced into the etched tube cavity to maintain a temperature between 130°C and 210°C at each joint. The heat from the fluid melts the inner walls of the first and second tubes, bonding them to the outer wall of the etched tube. This solution eliminates the processes of wrapping and removing heat shrink tubing, simplifying the process and reducing costs.

[0043] Preferably, a rigid support is built into step 1; specifically, a thin core rod is lined inside the cavity of the etching tube, the outer diameter of which is smaller than the inner diameter of the cavity of the etching tube; the thin core rod is axially supported or connected to the etching tube, so that the thin core rod and the etching tube are inserted into the cavities of the first tube and the second tube together.

[0044] In step 1, the rigid support inside the etched tube is removed after the etched tube is inserted.

[0045] In addition, step 4 is included: after fixing, the portions of the etched tubes that extend beyond the first and second tubes are cut off.

[0046] Preferably, in step 1, the outer diameter of the etching tube is larger than the inner diameter of the first tube and the second tube, and the etching tube passes through the lumen of the first tube and the second tube in a radially contracted state; specifically, the outer diameter circumference L1 of the etching tube satisfies the following relationship with the inner diameter circumference L3 of the first tube and the inner diameter circumference L4 of the second tube: L1 is between 105% and 115% of L3, and L1 is between 105% and 115% of L4.

[0047] A third objective of this invention is to provide a medical catheter fitting, characterized in that it is manufactured by the molding method described above, or by connecting two or more polymer medical catheter fittings by the connection method described above. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of step 1 in the medical catheter fitting forming method of Example 1.

[0049] Figure 2 This is a schematic diagram of step 3 in the medical catheter fitting forming method involved in Example 1.

[0050] Figure 3 This is a schematic diagram of step 4 in the medical catheter fitting forming method of Example 1.

[0051] Figure 4 This is a schematic diagram of step 1 in the medical catheter fitting forming method involved in Example 2.

[0052] Figure 5 This is a schematic diagram of step 3 in the medical catheter fitting forming method involved in Example 2.

[0053] Figure 6 This is a schematic diagram of step 4 in the medical catheter fitting forming method involved in Example 2. Detailed Implementation

[0054] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] 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," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are 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.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0057] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0059] Although the present invention describes steps 1, 2, or similar steps in sequence, this is only for clarity and conciseness. In fact, as long as it conforms to the purpose and technical solution of the present invention, the steps can be changed as needed based on the technical principles, and these changed steps also fall within the protection scope of the present invention.

[0060] The external lumen tube referred to in this case can be a single-lumen tube or a multi-lumen tube.

[0061] Example 1:

[0062] like Figure 1-3 As shown, this embodiment relates to a method for molding polymer medical catheter fittings, including the following steps:

[0063] Step 1: Insert the rigidly supported etching tube 1 into the cavity of the outer tube 2 from the beginning of the cavity and extend it from the end of the cavity of the outer tube 2; after inserting the tube, remove the rigid support inside the etching tube 1 (i.e., the removal of the thin mandrel below).

[0064] Step 2: Make the diameter of the tail end of the etching tube 1 smaller than the diameter of the starting end of the etching tube 1.

[0065] Step 3: Fluid is injected into the cavity of the etching tube 1 from the beginning. The fluid is sufficient to expand the cavity of the etching tube 1 so that the outer wall of the etching tube 1 fits against the inner wall of the outer cavity tube 2. The temperature of the fluid is set to maintain the temperature at the joint between 130°C and 210°C, so that the inner wall of the outer cavity tube 2 melts and combines with the outer wall of the etching tube 1.

[0066] Step 4: After fixing, cut off the portions of the etched tube 1 that extend beyond the outer cavity tube 2.

[0067] The molding method of this polymer medical catheter fitting has the same characteristics as the prior art in that: an etched tube 1 is fixed inside the outer lumen tube 2. The setting of the etched tube 1 can achieve the following effects: the smoothness requirement of the catheter fitting is high, so that the guide wire or other instruments inserted into the catheter can be inserted more smoothly; it can be applied to the connection between multiple catheter fittings.

[0068] Based on this, this solution differs from existing technologies and offers the following innovations:

[0069] This solution abandons the existing mandrel-supported approach and instead adopts a fluid expansion-supported approach. This eliminates the need to insert a high-precision mandrel into the cavity of the etching tube 1, reducing processing requirements and eliminating the step of inserting the mandrel into the cavity of the etching tube 1 using an interference fit, thus improving processing efficiency. Furthermore, it avoids the problem of insufficient mandrel precision or roundness preventing insertion into the tube.

[0070] This solution eliminates the need for external heat shrink tubing and the placement of the conduit within the rheometer. Instead, fluid—a gas, liquid, or gas-liquid mixture—is introduced into the cavity of the etched tube 1. The heat from the fluid melts the inner wall of the outer tube 2, bonding it to the outer wall of the etched tube 1. This solution eliminates the processes of wrapping and removing heat shrink tubing, simplifying the process and reducing costs.

[0071] It should be noted that this scheme requires the fluid to flow inside the cavity of the etching tube 1, and the diameter of the tail end of the etching tube 1 is smaller than the diameter of the starting end. This ensures that the inflow velocity of the fluid is greater than the outflow velocity, allowing the fluid to accumulate within the cavity of the etching tube 1. This, in turn, causes the fluid to expand the cavity of the etching tube 1, bringing the outer wall of the etching tube 1 into contact with the inner wall of the outer cavity tube 2.

[0072] In the specific implementation of step 1, a thin mandrel 3 is lined inside the cavity of the etching tube 1. In this scheme, the thin mandrel 3 provides support within the cavity of the etching tube 1, allowing it to reach the working position even when the outer cavity tube 2 is long. Without the support of the thin mandrel 3, the etching tube 1, without internal support, may not be able to reach the working position located inside the outer cavity tube 2. In this scheme, the thin mandrel 3 has an outer diameter smaller than the inner diameter of the etching tube 1's cavity (requiring no interference fit), providing sufficient rigidity and enabling it to quickly and smoothly penetrate into the etching tube 1; furthermore, it has no requirements regarding precision or roundness.

[0073] In this scheme, the thin core rod 3 is axially supported or connected to the etching tube 1, so that the thin core rod 3 and the etching tube 1 are inserted into the cavity of the outer tube 2 together, thus the thin core rod 3 and the etching tube 1 can move axially synchronously.

[0074] In a further embodiment, in step 1, the outer diameter of the etching tube 1 is larger than the inner diameter of the outer cavity tube 2, and the etching tube 1 passes through the cavity of the outer cavity tube 2 in a radially contracted state. In other technical solutions besides this application, because the outer cavity tube 2 is also covered with heat-shrink tubing, the inner wall of the outer cavity tube 2 can be made to fit against the outer wall of the etching tube 1 under the tightening force of the heat-shrink tubing. However, this embodiment omits the heat-shrink tubing, relying solely on the expansion of the internal fluid to make the inner wall of the outer cavity tube 2 fit against the outer wall of the etching tube 1. Furthermore, the cavity of the outer cavity tube 2 is not completely closed but rather open. Under these circumstances, relying solely on the expansion of the internal fluid is insufficient to achieve a good bonding effect. Therefore, in this embodiment, the outer diameter of the etching tube 1 is larger than the inner diameter of the outer cavity tube 2, so that the etching tube 1 can fit better against the inner wall of the outer cavity tube 2 when it is in an expanded state. Furthermore, to facilitate the insertion of the etching tube 1 into the outer cavity tube 2, the etching tube 1 is inserted in a radially contracted state during the insertion process. Here, the end of the etching tube 1 can be sealed, and then the gas inside the etching tube 1 can be extracted to make it contract.

[0075] In a specific implementation, the outer diameter circumference L1 of the etched tube 1 and the inner diameter circumference L2 of the outer cavity tube 2 satisfy the following relationship: L1 = L2 × (105% ~ 115%), that is, L1 is between 105% and 115% of L2. Meeting this ratio requirement allows the etched tube 1 to fit well against the inner wall of the outer cavity tube 2 in its expanded state. On the one hand, the moderately surplus portion of the etched tube 1 can provide material for the welding of the etched tube 1 and the outer cavity tube 2; on the other hand, it can also avoid excessive surplus that would cause wrinkles and unevenness in the etched tube 1.

[0076] In a further embodiment, in step 2, the diameter of the tail end of the etched tube 1 is made smaller than the diameter of the starting end of the etched tube 1. One of the following two methods can be adopted:

[0077] Option 1: The selected etched tube 1 has a reducing pipe section 11 at its tail end, with the inner diameter gradually decreasing from front to back. The reducing pipe section 11 extends from the tail end of the outer tube 2. In this option, the etched tube 1 directly constructs the reducing pipe section 11 or is connected to the reducing pipe section 11, extending the reducing pipe section 11 out of the tail end of the outer tube 2. This makes it convenient to cut off the reducing pipe section 11 after processing, thus not affecting subsequent use.

[0078] Option 2: The portion of the etched tube 1 extending beyond the outer cavity tube 2 is narrowed to make the diameter of the tail end of the etched tube 1 smaller than the diameter of the starting end. In this option, after the etched tube 1 is inserted into the outer cavity tube 2, the portion extending beyond the outer cavity tube 2 is narrowed, achieving both diameter reduction and narrowing. After processing, the excess portion is simply cut off.

[0079] Example 2:

[0080] like Figure 4-6 As shown, this embodiment provides a method for connecting polymer medical catheter fittings, including the following steps:

[0081] Step 1: Insert the etched tube 1 with built-in rigid support through the first tube 21 and into the second tube 22. The etched tube 1 is located at the connection between the first tube 21 and the second tube 22, and the etched tube 1 extends from the tail end of the first tube 21 or the second tube 22. After inserting the tube, remove the rigid support inside the etched tube 1 (that is, the removal of the thin core rod below).

[0082] Step 2: Make the diameter of the tail end 10 of the etching tube smaller than the diameter of the starting end of the etching tube 1.

[0083] Step 3: Fluid is injected into the cavity of the etching tube 1 from the beginning. The fluid is sufficient to expand the cavity of the etching tube 1 so that the outer wall of the etching tube 1 is in contact with the inner walls of the first tube 21 and the second tube 22. The fluid keeps the temperature of each joint between 130°C and 210°C, so that the inner walls of the first tube 21 and the second tube 22 melt and combine with the outer wall of the etching tube 1.

[0084] Step 4: After fixing, cut off the portions of the first and second tubes 21 and 22 that extend beyond the first tube 21 and the second tube 22 at both ends of the etched tube 1.

[0085] This technical solution relates to a connection method for polymer medical catheter fittings, mainly used to connect and fix two or more polymer medical catheters. Similar to existing technologies, the fittings still utilize built-in etched tubes for connection. The etched tube design ensures a secure connection at the catheter tip and maintains the smoothness of the inner wall at the connection point. Furthermore, this solution abandons the mandrel-supported approach of existing technologies, instead employing a fluid expansion-supported approach. This eliminates the need to insert a high-precision mandrel into the etched tube cavity, reducing processing requirements and simplifying the process by avoiding the step of inserting the mandrel into the etched tube cavity using an interference fit. It also eliminates the problem of insufficient mandrel precision or roundness preventing tube insertion.

[0086] Furthermore, this solution eliminates the need for external heat shrink tubing and the placement of the conduit within the rheometer. Instead, a fluid is introduced into the etched tube cavity to maintain a temperature between 130°C and 210°C at each joint. The heat from the fluid melts the inner walls of the first tube 21 and the second tube 22, bonding them to the outer wall of the etched tube. This solution eliminates the processes of wrapping and removing heat shrink tubing, simplifying the process and reducing costs.

[0087] In the preferred embodiment, in step 1, the outer diameter of the etching tube 1 is larger than the inner diameter of the first tube 21 and the second tube 22, and the etching tube 1 passes through the cavities of the first tube 21 and the second tube 22 in a radially contracted state; specifically, the outer diameter circumference L1 of the etching tube 1 satisfies the following relationship with the inner diameter circumference L3 of the first tube 21 and the inner diameter circumference L4 of the second tube 22: L1 is between 105% and 115% of L3, and L1 is between 105% and 115% of L4.

[0088] Furthermore, the rigid support built into the etching tube 1 in this embodiment, and the tapering structure of the etching tube tail end 10 in step 2, can be referred to the contents described in embodiment 1.

[0089] Example 3:

[0090] A medical catheter fitting is manufactured using the molding method described in Example 1, or by connecting two or more polymer medical catheter fittings using the connection method described in Example 2.

[0091] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0092] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for molding polymer medical catheter fittings, characterized in that: Includes the following steps: Step 1: Insert the etching tube (1) into the lumen of the outer tube (2) from the beginning of the lumen and extend it from the end of the lumen of the outer tube (2); Step 2: The selected etching tube tail end (10) is a variable diameter tube section (11) whose inner diameter gradually decreases from front to back. The variable diameter tube section (11) extends out from the tail end of the outer cavity tube (2); or the part of the etching tube tail end (10) that extends beyond the outer cavity tube (2) is closed off so that the diameter of the etching tube tail end (10) is smaller than the diameter of the starting port of the etching tube (1). Step 3: Fluid is injected into the cavity of the etching tube (1) from the beginning. The fluid is sufficient to open the cavity of the etching tube (1) so that the outer wall of the etching tube (1) fits against the inner wall of the outer cavity tube (2). The fluid keeps the temperature at each joint between 130°C and 210°C so that the inner wall of the outer cavity tube (2) melts and combines with the outer wall of the etching tube (1).

2. The molding method for polymer medical catheter fittings according to claim 1, characterized in that: In step 1, the etching tube (1) has a rigid support inside, and a thin core rod (3) is lined inside the cavity of the etching tube (1). The outer diameter of the thin core rod (3) is smaller than the inner diameter of the cavity of the etching tube (1). The thin core rod (3) is axially supported or connected to the etching tube (1), so that the thin core rod (3) and the etching tube (1) are inserted into the cavity of the outer cavity tube (2) together. After the etching tube (1) is inserted, the rigid support inside the etching tube (1) is removed.

3. The molding method for polymer medical catheter fittings according to claim 1, characterized in that: It also includes step 4: cutting off the portion of the etched tube (1) that extends beyond the outer cavity tube (2).

4. The molding method for polymer medical catheter fittings according to claim 1, characterized in that: In step 1, the outer diameter of the etching tube (1) is larger than the inner diameter of the outer cavity tube (2), and the etching tube (1) passes through the cavity of the outer cavity tube (2) in a radially contracted state; specifically, the outer diameter circumference L1 of the etching tube (1) and the inner diameter circumference L2 of the outer cavity tube (2) satisfy the following relationship: L1 is between 105% and 115% of L2.

5. A method for connecting polymer medical catheter fittings, characterized in that: Includes the following steps: Step 1: Use an etched tube (1) to pass through the first tube (21) and insert it into the second tube (22). The etched tube (1) is located at the connection between the first tube (21) and the second tube (22), and the etched tube (1) extends from the tail end of the first tube (21) or the second tube (22). Step 2, make the diameter of the tail end (10) of the etching tube smaller than the diameter of the starting end of the etching tube (1); Step 3: Fluid is injected into the cavity of the etching tube (1) from the beginning. The fluid is sufficient to open the cavity of the etching tube (1) so that the outer wall of the etching tube (1) is in contact with the inner wall of the first tube (21) and the second tube (22). The fluid keeps the temperature of each joint between 130°C and 210°C, so that the inner wall of the first tube (21) and the second tube (22) melts and combines with the outer wall of the etching tube (1).

6. The connection method for polymer medical catheter fittings according to claim 5, characterized in that: In step 1, the etching tube (1) has a rigid support inside, and a thin core rod (3) is lined inside the cavity of the etching tube (1). The outer diameter of the thin core rod (3) is smaller than the inner diameter of the cavity of the etching tube (1). The thin core rod (3) is axially supported or connected to the etching tube (1), so that the thin core rod (3) and the etching tube (1) are inserted into the cavities of the first tube (21) and the second tube (22) together. After the etching tube (1) is inserted, the rigid support inside the etching tube (1) is removed.

7. The connection method for polymer medical catheter fittings according to claim 5, characterized in that: It also includes step 4: after fixing, cut off the portions of the first and second tubes (21 and 22) of the etched tube (1).

8. The connection method for polymer medical catheter fittings according to claim 5, characterized in that: In step 1, the outer diameter of the etching tube (1) is larger than the inner diameter of the first tube (21) and the second tube (22). The etching tube (1) passes through the lumen of the first tube (21) and the second tube (22) in a radially contracted state. Specifically, the outer diameter circumference L1 of the etching tube (1) satisfies the following relationship with the inner diameter circumference L3 of the first tube (21) and the inner diameter circumference L4 of the second tube (22): L1 is between 105% and 115% of L3, and L1 is between 105% and 115% of L4.

9. A medical catheter fitting, characterized in that: It is made by molding method according to any one of claims 1-4, or by connecting two or more polymer medical catheters by connection method according to any one of claims 5-8.

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