Interventional multi-lumen medical catheter precision gas-assisted extrusion molding control system

Abstract

The present application relates to the technical field of medical device forming control, and specifically discloses an interventional multi-lumen medical catheter precision gas-assisted extrusion forming control system, which realizes real-time acquisition of melt properties, melt process and gas process parameters; constructs a dynamic gas-assisted control mapping table through collaborative optimization based on the acquired parameters; realizes real-time collaborative adjustment of the gas pressures of the outer part and each inner-lumen gas-assisted layer according to the mapping table, and synchronously forms a uniform and isolated multi-layer gas-assisted wrapping flow field at the melt circumferential and internal lumen interface; dynamically adjusts the local flow rate and overall pulling rate of the melt in the die based on the flow field, realizes precision extrusion forming, and realizes online monitoring of product morphology and surface state data; simultaneously with the extrusion forming, adjusts and controls the injection position and atomization distribution of the anti-inflammatory aerosol according to the mapping table and real-time data, so that the anti-inflammatory aerosol is uniformly deposited on the surface of the catheter under the guidance of the multi-layer gas-assisted flow field; and the present application solves the problems of die separation expansion, deformation, rupture and surface burrs in the extrusion of traditional multi-lumen catheters.

Description

Technical Field

[0001] This invention relates to the field of medical device molding control technology, specifically to a precision air-assisted extrusion molding control system for interventional multi-lumen medical catheters. Background Technology

[0002] Interventional multi-lumen medical catheters (such as double-lumen and triple-lumen catheters) are commonly used devices in clinical medicine. The independence and dimensional accuracy of their functional lumens directly affect the effectiveness and safety of procedures such as drainage, irrigation, and pressure measurement. Currently, these catheters are mainly made of polymer materials through traditional extrusion processes.

[0003] The key and rare challenge in the current technology of single continuous extrusion molding of interventional multi-lumen medical catheters is how to achieve uniform and firm in-situ anti-inflammatory functional modification on the surfaces of multiple small, deep and isolated internal cavities at the same time. Traditional methods cannot effectively apply and distribute functional materials in closed, microscale complex cavities, and can only rely on secondary processing after molding, resulting in uneven modification, poor bonding force and cumbersome process. Summary of the Invention

[0004] The purpose of this invention is to provide a precision air-assisted extrusion molding control system for interventional multi-lumen medical catheters to solve the problems mentioned above.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A precision pneumatic-assisted extrusion molding control system for an interventional multi-lumen medical catheter includes:

[0007] The process parameter synchronous acquisition module is used to acquire melt physical property parameters, melt process parameters and gas process parameters. The melt process parameters include melt flow rate and melt temperature. The gas process parameters include external gas-assisted pressure and gas-assisted pressure of multiple internal cavities.

[0008] The dynamic gas-assisted control strategy generation module is used to input melt physical property parameters, melt process parameters and gas process parameters into the co-optimization algorithm for coupled calculation, and generate a dynamic gas-assisted control mapping table that matches the multi-cavity structure. The dynamic gas-assisted control mapping table includes: external gas-assisted layer pressure gradient, pressure coordination relationship of each internal cavity gas-assisted layer and gas-assisted action timing.

[0009] The multi-layer gas-assisted flow field coordinated control module adjusts the gas pressure of the external gas-assisted layer and each inner cavity gas-assisted layer in real time according to the dynamic gas-assisted control mapping table, and simultaneously forms a uniform and isolated multi-layer gas-assisted encapsulation flow field at the interface of the internal cavity in the circumferential direction of the melt.

[0010] The precision extrusion and online monitoring module, based on a multi-layer gas-assisted encapsulation flow field, dynamically adjusts the local flow rate of the melt in the die and the overall extrusion traction rate to perform precision extrusion molding of multi-lumen catheters, and simultaneously acquires real-time morphology and surface state data during the extrusion process.

[0011] The in-situ surface anti-inflammatory modification integrated module is used to regulate the injection position and atomization distribution of anti-inflammatory aerosols based on a dynamic gas-assisted control mapping table and real-time morphology and surface state data during precision extrusion molding, so that the anti-inflammatory aerosols are uniformly deposited on the surface of the catheter under the action of a multi-layer gas-assisted encapsulation flow field.

[0012] As a further aspect of the present invention: the generation of a dynamic gas-assisted control mapping table matching the multi-cavity structure specifically includes:

[0013] Based on the collected melt physical property parameters, melt process parameters and gas process parameters, a multi-dimensional parameter vector reflecting the multi-cavity structural characteristics and process objectives is constructed.

[0014] Based on multidimensional parameter vectors, the segmented pressure distribution of the external gas-assisted layer along the axial direction corresponding to each extrusion stage is determined by nonlinear time-series mapping reconstruction, as well as the dynamic pressure ratio between multiple internal gas-assisted layers as the extrusion process progresses.

[0015] Based on the segmented pressure distribution and dynamic pressure ratio, a dynamic gas-assisted control mapping table is generated that simultaneously includes pressure gradient information, cooperative relationships, and precise temporal relationships.

[0016] As a further aspect of the present invention: the determination of the segmented pressure distribution along the axial direction of the external gas-assisted layer corresponding to each extrusion stage, and the dynamic pressure ratio between multiple internal gas-assisted layers as the extrusion process is based on a multi-dimensional parameter vector and reconstructed through a nonlinear time-series mapping method, specifically includes:

[0017] The multidimensional parameter vector is segmented along the extrusion axis to extract key feature vectors corresponding to each extrusion segment.

[0018] Based on key feature vectors, the pressure reference value required to be maintained by the internal and external gas-assisted layers of each section and the initial pressure ratio between multiple internal cavity gas-assisted layers are determined by reconstructing the state of the extrusion process sequence.

[0019] Based on the pressure baseline and initial pressure ratio, and combined with the preset flow field equilibrium target, a distribution rule is constructed to map the extrusion time sequence as the segmented pressure distribution of the external gas-assisted layer and the dynamic pressure ratio of the internal gas-assisted layer.

[0020] As a further aspect of the present invention: the formation process of the multi-layered air-assisted encapsulation flow field is as follows:

[0021] Based on the dynamic gas-assisted control mapping table, in the initial section where the melt enters the die, a main gas-assisted layer is established to enclose the outer periphery of the melt according to the pressure gradient of the external gas-assisted layer.

[0022] After the main gas-assisted layer is stably established, auxiliary gas is injected into multiple internal cavity channels simultaneously according to the pressure coordination relationship of each internal cavity gas-assisted layer, so that each internal cavity interface forms a secondary gas-assisted layer that matches the pressure of the main gas-assisted layer.

[0023] Based on the timing of gas-assisted action, the gas pressure of the main gas-assisted layer and each secondary gas-assisted layer is dynamically fine-tuned to ensure that the melt maintains a balanced stress state at all gas-assisted interfaces, forming a multi-layer gas-assisted encapsulation flow field.

[0024] As a further aspect of the present invention: the dynamic fine-tuning of the gas pressure of the main gas-assisted layer and each secondary gas-assisted layer based on the gas-assisted action timing specifically includes:

[0025] Based on the timing of gas-assisted extrusion, the extrusion process is divided into three consecutive stages: melt filling, preliminary forming, and stabilization.

[0026] During the melt filling stage, the pressure of the secondary gas-assisted layer is actively matched with the pressure of the primary gas-assisted layer to form initial synergy;

[0027] In the initial forming stage, with the goal of maintaining the equilibrium of each interface of the melt, the pressure difference between the main gas-assisted layer and each secondary gas-assisted layer is calculated and compensated in real time.

[0028] During the stabilization and finalization stage, the gas pressure of the main gas auxiliary layer and each secondary gas auxiliary layer is adjusted and locked proportionally based on the pressure state after compensation in the previous stage.

[0029] As a further aspect of the present invention: the dynamic adjustment of the local flow rate of the melt within the die and the overall extrusion traction rate to perform precision extrusion molding of a multi-lumen catheter, and simultaneously acquiring real-time morphology and surface state data during the extrusion process, specifically includes:

[0030] Based on the pressure distribution detected in the multi-layer gas-assisted encapsulation flow field, the local velocity adjustment targets for each corresponding region within the die are determined.

[0031] Based on the local flow velocity adjustment targets of each region, the correction command for the overall extrusion traction rate is calculated collaboratively and output.

[0032] During the execution of correction instructions, real-time morphology and surface condition data reflecting the outer diameter, roundness, and surface roughness of the product are simultaneously collected by online contour scanning and surface finish sensing units arranged along the extrusion direction.

[0033] As a further aspect of the present invention: determining the local velocity adjustment target for each corresponding region within the die based on the pressure distribution detected in the multi-layer gas-assisted encapsulation flow field specifically includes:

[0034] Based on the pressure values ​​of each layer detected synchronously in the multi-layer gas-assisted encapsulation flow field, pressure fluctuation characteristics representing flow stability at the melt-gas interface are extracted.

[0035] Based on pressure fluctuation characteristics, regions within the exit die associated with the fluctuation characteristics are identified, and the impact of each region on extrusion uniformity is assessed.

[0036] Based on the degree of influence, the pressure fluctuation characteristics are inversely mapped to the local velocity increase or decrease of the melt in each region to compensate for the non-uniformity of the flow, and the local velocity increase or decrease of the melt is set as the target for local velocity adjustment.

[0037] As a further aspect of the present invention: the regulation of the injection location and atomization distribution of the anti-inflammatory aerosol specifically includes:

[0038] Based on the gas-assisted action timing and external gas-assisted layer pressure gradient defined in the dynamic gas-assisted control mapping table, and combined with the preset anti-inflammatory aerosol physical property parameters, the expected deposition path and pattern to be followed in the multi-layer gas-assisted encapsulated flow field are determined.

[0039] Based on the surface roughness and morphology characteristics of the catheter reflected in the real-time morphology and surface condition data, the expected deposition path and pattern are dynamically corrected to match the actual surface profile of the current extruded product.

[0040] Based on the modified deposition path and pattern, the circumferential and axial positions of the anti-inflammatory aerosol injection point near the die outlet are adjusted in real time, and the pressure and flow rate of the atomizing medium are controlled simultaneously to achieve in-situ uniform deposition of anti-inflammatory components under the guidance of the air-assisted flow field.

[0041] As a further aspect of the present invention: the dynamic correction specifically includes:

[0042] Feature parameters representing changes in surface micro-contours are extracted from real-time morphology and surface state data.

[0043] The feature parameters are compared with the preset reference profile to calculate and generate a profile deviation vector that represents the deviation between the actual surface and the expected surface.

[0044] The contour deviation vector is inversely mapped to the aerosol control domain to generate correction instructions for injection angle, atomization cone angle and coverage density to compensate for the deviation.

[0045] Based on the correction instructions, the control parameters of the deposition path and mode are updated in real time.

[0046] The beneficial effects of this invention are:

[0047] (1) This invention constructs a precision control system with "gas-melt-gas" multiphase flow coupling, and uses a generated dynamic gas-assisted control mapping table to perform real-time, coordinated closed-loop regulation of the gas-assisted pressure in the external environment and multiple internal cavities. This results in a stable, uniform, and mutually isolated multi-layered gas-assisted encapsulation flow field being formed synchronously on the outside of the melt and at all internal cavity interfaces. This flow field can effectively suppress the non-uniform flow of the melt in the die, weaken or eliminate the phenomena of "die expansion" and "extrusion deformation"; at the same time, the lubrication effect of the gas interface avoids direct adhesive shearing between the melt and the die wall, thereby preventing the generation of "melt fracture" and "surface burrs". This reduces subsequent processing and finishing steps and improves the consistency and reliability of the product.

[0048] (2) This invention organically integrates the deposition process of anti-inflammatory aerosols into the gas-assisted extrusion molding process. By dynamically adjusting the spray position and atomization state of the aerosol and compensating for circumferential motion based on the dynamic gas-assisted control mapping table and real-time morphology data, the anti-inflammatory active ingredients can be precisely guided by the multi-layer gas-assisted encapsulation flow field and adhere to the surface of the conduit melt in situ at the moment of extrusion molding. This method not only avoids the problems of uneven coating, weak bonding force, and low efficiency that may be caused by traditional secondary impregnation or coating processes, but also utilizes the hot melt surface of the extrusion process to achieve the physicochemical bonding between the anti-inflammatory agent and the pipe wall material, thereby obtaining a strong anti-inflammatory functional layer with an increased effective duration of anti-inflammatory action. Attached Figure Description

[0049] The invention will now be further described with reference to the accompanying drawings.

[0050] Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Please see Figure 1 As shown, the present invention is a precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter, comprising:

[0053] The process parameter synchronous acquisition module is used to acquire melt physical property parameters, melt process parameters and gas process parameters. The melt process parameters include melt flow rate and melt temperature. The gas process parameters include external gas-assisted pressure and gas-assisted pressure of multiple internal cavities.

[0054] The dynamic gas-assisted control strategy generation module is used to input melt physical property parameters, melt process parameters and gas process parameters into the co-optimization algorithm for coupled calculation, and generate a dynamic gas-assisted control mapping table that matches the multi-cavity structure. The dynamic gas-assisted control mapping table includes: external gas-assisted layer pressure gradient, pressure coordination relationship of each internal cavity gas-assisted layer and gas-assisted action timing.

[0055] The multi-layer gas-assisted flow field coordinated control module adjusts the gas pressure of the external gas-assisted layer and each inner cavity gas-assisted layer in real time according to the dynamic gas-assisted control mapping table, and simultaneously forms a uniform and isolated multi-layer gas-assisted encapsulation flow field at the interface of the internal cavity in the circumferential direction of the melt.

[0056] The precision extrusion and online monitoring module, based on a multi-layer gas-assisted encapsulation flow field, dynamically adjusts the local flow rate of the melt in the die and the overall extrusion traction rate to perform precision extrusion molding of multi-lumen catheters, and simultaneously acquires real-time morphology and surface state data during the extrusion process.

[0057] The in-situ surface anti-inflammatory modification integrated module is used to regulate the injection position and atomization distribution of anti-inflammatory aerosols based on a dynamic gas-assisted control mapping table and real-time morphology and surface state data during precision extrusion molding, so that the anti-inflammatory aerosols are uniformly deposited on the surface of the catheter under the action of a multi-layer gas-assisted encapsulation flow field.

[0058] In the process parameter synchronous acquisition module, firstly, regarding the melt physical property parameters, which refer to the inherent properties of the polymer materials used (such as medical-grade silicone rubber or polyurethane), including but not limited to melt viscosity, density, and rheological behavior index. These parameters can be obtained by measuring the raw materials used with standard material testing equipment such as rheometers and densitometers before the extrusion process begins, and provide basic data for subsequent modeling and control.

[0059] Secondly, melt process parameters are collected in real time during extruder operation. Melt flow rate is monitored and fed back through a melt gear pump or mass flow meter installed in the metering section of the extruder or at the die inlet. Melt temperature is measured at multiple points using thermocouples embedded in multiple heating zones of the extruder barrel and in the die flow channel to obtain the temperature distribution of the melt throughout the entire process from plasticizing to extrusion.

[0060] Finally, the acquisition of gas process parameters is completed synchronously during the operation of the gas-assisted system. External gas-assisted pressure refers to the gas pressure applied to the annular air gap between the inner wall of the die and the outer surface of the melt, acquired through a precision pressure sensor installed in the external gas-assisted gas pipeline. Multiple internal cavity gas-assisted pressures correspond to the auxiliary gas pressure supplied to each independent internal cavity forming channel, and are independently monitored through pressure sensors on each internal cavity gas-assisted branch. Signals from all sensors are acquired in real time and transmitted to the central controller.

[0061] In the dynamic gas-assisted control strategy generation module, a multi-dimensional parameter vector reflecting the multi-cavity structural characteristics and process objectives is first constructed. This process integrates the collected discrete parameters into a structured dataset. Specifically, this vector contains data in the following dimensions: the apparent viscosity of the melt at the set temperature, the melt density, the real-time melt flow rate, the average temperature of multiple measurement points of the melt, the real-time value of the external gas-assisted pressure, and the real-time value of the gas-assisted pressure for each cavity. Simultaneously, the multi-cavity structural characteristics, namely the number of lumens in the catheter, the preset geometric dimensions of each lumen, and their relative positions, are also quantified as fixed dimensions in the vector. The process objectives are set as the desired outer diameter of the product, wall thickness uniformity, and surface finish grade; these target values ​​are also components of the vector. All parameters are stored in floating-point form and arranged in a preset order, collectively forming a one-dimensional multi-dimensional parameter vector.

[0062] Secondly, based on this multidimensional parameter vector, the axial segmental pressure distribution of the external gas-assisted layer and the dynamic pressure ratio between the internal gas-assisted layers are determined through a nonlinear time-series mapping reconstruction method, corresponding to each extrusion stage. This process is implemented by the computational logic in the control software and specifically includes three sequentially executed sub-steps.

[0063] The first sub-step involves segmented feature extraction along the extrusion axis. Based on the physical length of the die and the stability of the extrusion process, the entire extrusion stroke is divided into 5 to 10 consecutive segments in the time series. For dynamic parameters related to the process state (such as flow rate, temperature, and pressure) in the multidimensional parameter vector, statistical characteristic values ​​are calculated for each segment, such as the mean and standard deviation of the parameters within that segment. These statistical characteristic values ​​are combined with the axial position code corresponding to that segment to form a key feature vector representing the process state of that segment.

[0064] The second sub-step determines the pressure baseline and ratio through state reconstruction of the extrusion process sequence. This step is based on the previously obtained key feature vector sequence. For each segment's key feature vector, it is input into a pre-trained computational model. The internal logic of this model is established by analyzing a large amount of historical process data, and its function is to establish a nonlinear correspondence between process state parameters and ideal gas-assisted pressure values. After receiving a key feature vector, the model outputs a set containing multiple pressure setpoints. In this set, the first value is the pressure baseline value that the internal and external gas-assisted layers of this segment need to maintain, and the subsequent values ​​represent the initial proportional coefficients between the pressure of each internal gas-assisted layer and this external pressure baseline value, such as 0.5 and 1.05.

[0065] The third sub-step is to construct the allocation rules to generate a complete pressure distribution and ratio sequence. The pressure baseline value sequences of all segments calculated above are connected in segment order to form a segment-by-segment pressure distribution along the axial direction of the external gas-assisted layer. Simultaneously, the calculated pressure ratio coefficients for each cavity in all segments are grouped by cavity number and arranged in segment order to form multiple dynamic pressure ratio sequences describing how the ratio of each cavity pressure to the external pressure changes over time (extrusion process).

[0066] Finally, the generated segmented pressure distribution and dynamic pressure ratio sequence are integrated to form the final dynamic gas-assisted control mapping table. This mapping table is a structured data list. Each row in the list corresponds to a specific, subdivided extrusion time point or axial position point. Each row of data contains the following fields: time point identifier, axial position identifier, target pressure value of the external gas-assisted layer at this moment, and target pressure value of each internal cavity gas-assisted layer at this moment (this value is calculated by multiplying the target external pressure value at this moment by the dynamic pressure ratio of the corresponding internal cavity at this moment). This table fully defines the pressure gradient of the external gas-assisted layer, the pressure coordination relationship between each internal cavity gas-assisted layer, and the precise control commands for the coordinated changes of the three with extrusion time (sequence).

[0067] In the multi-layer gas-assisted flow field collaborative control module, a primary gas-assisted layer is first established to enclose the outer periphery of the melt. When the melt tip enters the initial forming section of the die, the gas path control unit adjusts the gas supply pipeline connected to the annular air gap outside the die according to the instruction corresponding to the current time point in the dynamic gas-assisted control mapping table. Specifically, the control unit drives the electro-pneumatic proportional valve on this pipeline to ensure that its output pressure precisely reaches the target pressure value of the external gas-assisted layer set for this initial section in the mapping table. This pressurized gas is uniformly ejected from the annular micro-gap on the die wall, forming a stable gas film, i.e., the primary gas-assisted layer, between the outer surface of the melt and the inner wall of the die. The pressure sensor monitors the actual pressure of this gas path in real time and provides feedback. The proportional-integral control algorithm quickly eliminates the deviation between the actual pressure and the target pressure, ensuring that the pressure of the primary gas-assisted layer remains stable from the beginning.

[0068] Secondly, multiple secondary gas-assisted layers matching the primary gas-assisted layer are established simultaneously. Once the pressure feedback value of the primary gas-assisted layer stabilizes within ±2% of the target pressure value for more than 0.5 seconds, the primary gas-assisted layer is considered stably established. At this point, based on the pressure coordination relationship of each cavity's gas-assisted layer defined at the same time point or the next time sequence point in the mapping table, control of each cavity's independent gas path is simultaneously initiated. For each cavity's gas path, its corresponding control unit independently drives an electro-pneumatic proportional valve, ensuring the output pressure of that cavity's gas path reaches its target value. This target value is calculated by multiplying the current target pressure of the external gas-assisted layer in the mapping table by the dynamic pressure ratio corresponding to that cavity. The pressurized gas in each cavity is introduced through micro-channels within the corresponding mandrel, forming an independent secondary gas-assisted layer between the melt and the forming surface of each cavity. Each cavity's gas path is equipped with an independent pressure sensor for closed-loop feedback control.

[0069] Finally, based on the timing of the gas-assisted operation, the pressure of the main gas-assisted layer and each secondary gas-assisted layer is dynamically fine-tuned to maintain overall equilibrium. This fine-tuning process divides the extrusion process into three consecutive stages for differentiated control, according to the preset timing logic in the mapping table.

[0070] The first stage is the melt filling stage, which occurs before the orifice cavity is completely filled with melt. In this stage, the control logic focuses on ensuring the rapid establishment of each gas-assisted layer and preventing melt blockage of the gas passages. The target pressure of the secondary gas-assisted layer is set to actively match the actual pressure feedback value of the current primary gas-assisted layer. Specifically, the pressure setting value of each internal cavity gas passage is equal to the measured pressure value of the current primary gas-assisted layer multiplied by a coefficient slightly less than 1 (e.g., 0.95), to quickly form initial coordinated support and prevent internal cavity collapse.

[0071] The second stage is the preliminary forming stage, which occurs from the time the melt completely fills the cavity until the extrudate enters the cooling water tank. The goal of this stage is to maintain a force balance in the melt at all gas-assisted interfaces. The control unit calculates the difference between the measured pressure value of each gas-assisted layer (one main gas-assisted layer and multiple secondary gas-assisted layers) and the target value at the current time point in the mapping table at a frequency of 10 times per second. These differences are then weighted and averaged to obtain a comprehensive pressure deviation value. Based on this comprehensive deviation value, the control logic performs a one-time, same-direction compensation adjustment to the pressure setpoints of all gas paths, simultaneously increasing or decreasing by a small increment (e.g., 1% to 2% of the target pressure), so that the overall pressure distribution approaches the ideal equilibrium state defined in the mapping table more quickly.

[0072] The third stage is the stabilization and setting stage, which occurs after the extrudate enters the cooling water bath and begins to solidify. In this stage, a lock-in fine-tuning is performed based on the final compensated pressure state at the end of the preliminary forming stage. The control unit records the actual stable pressure values ​​of each air path at the end of the preliminary forming stage and uses these values ​​as the new pressure reference for this stage. In this stage, the control objective becomes maintaining the absolute stability of these reference values. If the measured pressure value of any air path fluctuates more than ±0.5% of its own reference value, an independent proportional adjustment action is triggered for that single air path, precisely adjusting its pressure back to the reference value, while the pressures of other air paths remain unchanged. This achieves proportional fine-tuning and locking of the pressure, ensuring extremely high stability of the flow field during the setting stage.

[0073] In the precision extrusion and online monitoring module, firstly, based on the pressure distribution detected in the multi-layer gas-assisted encapsulation flow field, the local flow velocity adjustment target for each corresponding region within the die is determined. This process is executed periodically once per second. Specifically, the historical pressure data from the pressure sensors of the external gas-assisted layer and each inner cavity gas-assisted layer are read at the current moment and within the past 2 seconds. For each layer of gas-assisted pressure data, its pressure fluctuation amplitude within that time period is calculated by taking the difference between the highest and lowest pressure values ​​within that time period. Simultaneously, its pressure change rate is calculated, i.e., the difference between the current pressure value and the pressure value one second ago. This fluctuation amplitude and change rate together constitute the pressure fluctuation characteristics reflecting the flow stability of the melt-gas interface at that location. Subsequently, according to the geometric design drawings of the die and mandrel, the annular flow channel inside the die and each inner cavity flow channel are divided into 5 to 8 consecutive physical regions along the axial direction, with each region associated with a specific set of pressure sensor monitoring points. Analysis revealed that if the average pressure fluctuation calculated from multiple associated pressure monitoring points in a certain area exceeds 3% of its target pressure value, the area is identified as a flow unstable region, and its impact on extrusion uniformity is directly proportional to this average fluctuation amplitude. Finally, based on the degree of influence of each identified region, a reverse mapping calculation is performed to determine the local flow rate adjustment. The mapping rule is as follows: for each region identified as unstable, the target adjustment value for the local melt flow rate is the original base flow rate multiplied by an adjustment coefficient. This adjustment coefficient is equal to 1 minus the ratio of the average pressure fluctuation amplitude of the region to a preset threshold (e.g., 5% of the target pressure value). For example, if the average fluctuation amplitude of a region is 4%, the adjustment coefficient is 1 minus (4% divided by 5%), i.e., 0.92, meaning the flow rate in that region needs to be reduced to 92% of its original value. The calculated percentage increase or decrease in flow rate is the local flow rate adjustment target for that region.

[0074] Secondly, based on the calculated local flow rate adjustment targets for each region, a correction command for the overall extrusion traction rate is calculated and output. The control unit summarizes the adjustment targets for all regions. The correction logic for the overall traction rate is as follows: First, identify the value among all region local flow rate adjustment target values ​​that deviates the largest from its base setting, and record it as the maximum deviation. Then, multiply the current overall extrusion traction rate setting by a compensation coefficient associated with the maximum deviation, which is preset to 1 plus half of the maximum deviation value. For example, if the maximum deviation is a reduction of 8% (i.e., coefficient 0.92), then the compensation coefficient is 1 plus (half of negative 8%, i.e., negative 4%), equal to 0.96. This means that the overall traction rate should be synchronously adjusted to 96% of the original value. The calculated new traction rate value is sent as a correction command to the servo drive of the traction machine for execution.

[0075] Finally, while executing the aforementioned traction rate correction command, online data acquisition is performed simultaneously. Approximately 10 cm downstream of the die exit, a laser profile scanner is installed perpendicular to the extrusion direction. This scanner performs a 360-degree circular scan of the outer surface of the passing extruded product at a frequency of 100 lines per second, acquiring its cross-sectional profile point cloud data. The minimum circumscribed circle diameter and the maximum inscribed circle diameter of this cross-section are calculated in real time using a software algorithm; their average value is used as the real-time outer diameter. Half the difference between the two is used as the ratio to the average outer diameter to evaluate roundness. Approximately 5 cm behind the laser scanner, a confocal white light surface finish sensor is installed. Its focused beam is aligned with the surface of the extruded product and performs an axial scan, measuring the microscopic undulations of the surface and obtaining the arithmetic mean deviation of the profile as surface roughness data. These outer diameter, roundness, and surface roughness data are acquired in real time, timestamped, and stored as a data stream reflecting the real-time morphology and surface condition of the product for process monitoring and subsequent analysis.

[0076] In the in-situ surface anti-inflammatory modification integrated module, while the precision extrusion molding process is running stably, the anti-inflammatory aerosol deposition process is regulated to achieve in-situ and uniform bonding of aerosols on the catheter surface. This regulation process is completed in three main stages based on a dynamic gas-assisted control mapping table and real-time morphology data: determining the expected deposition path, making dynamic corrections, and finally executing precise control.

[0077] The first stage involves determining the expected deposition path and pattern of the anti-inflammatory aerosol in a multi-layered gas-assisted encapsulation flow field. This stage is based on the gas-assisted action timing and external gas-assisted layer pressure gradient data defined in the dynamic gas-assisted control mapping table. Specifically, the target external gas-assisted layer pressure value corresponding to the current extrusion time point is selected from the mapping table. (Unit: Pascal), and the rate of pressure change between the current point and the next time point. Simultaneously, the physical properties of the anti-inflammatory aerosol used in this process are retrieved from the preset database, primarily including its typical particle size. (Unit: meters) and dynamic viscosity at process temperature (Unit: Pascal-second). The core parameter of the expected deposition path is the theoretical vertical distance from the aerosol jet nozzle to the deposition point on the catheter surface. (Unit: meters), calculated using the following formula: ;

[0078] In this calculation formula, Indicates the characteristic frequency of the air-assisted flow field The average gas velocity obtained from the flow field simulation at 1 Hz is expressed in meters per second. The characteristic flight time of aerosol particles from injection to the intended contact surface, in seconds, is preset to 0.01 to 0.1 seconds. It is a reference pressure constant, set to 100,000 Pascals, used for dimensionless designation. and These are dimensionless empirical coefficients obtained by fitting a large amount of process experimental data, where... The typical value range is 0.5 to 1.2. The typical value range is 0.1 to 0.3. The physical meaning of this formula is that higher external pneumatic pressure... This will compress the flow field space, thus potentially shortening the deposition distance. aerosol viscosity The increase in this will enhance its following ability, thus expecting an increase in deposition distance. Calculated... Based on the timing of the gas-assisted deposition, which indicates that the current stage is "stable and well-defined", the expected depositional pattern is determined to be "stable laminar flow encapsulation deposition".

[0079] In the second stage, the expected path and pattern are dynamically corrected based on real-time morphology and surface condition data. First, the surface roughness within the most recent 2 seconds is extracted from the real-time data stream acquired through online monitoring. Calculate the arithmetic mean of the continuous measurements. with standard deviation Simultaneously, the maximum and minimum radii of the current cross-section are extracted from the laser profile data. , The radius difference, along with half of the radius difference (i.e., the out-of-roundness magnitude), is combined into a feature parameter vector. This vector is then compared element-by-element with a preset reference profile parameter vector (representing the roughness and roundness values ​​of an ideal smooth cylindrical surface). The method for calculating the profile deviation vector is to take the square root of the sum of the squares of the differences between corresponding elements in the two vectors, obtaining a scalar value characterizing the overall deviation. Next, this The mapping is then reversed to the aerosol control domain to generate correction commands. The specific mapping rule is: injection angle correction amount. (Unit: degrees) equals Multiply by an angle sensitivity factor (e.g., 30); atomization cone angle correction amount (Unit: degrees) equals Multiply by a cone-angle diffusion coefficient (e.g., 15); Cover density correction factor (Dimensionless) equals 1 minus The ratio to the reference roughness. These calculations aim to make aerosol spraying more adaptable to the inhomogeneities of real surfaces.

[0080] The third stage involves real-time control based on the corrected deposition path and pattern. First, based on the corrected expected deposition distance... (This value is calculated by the first stage) (Multiplied by the coverage density correction factor β), the spatial position of the anti-inflammatory aerosol injection point is adjusted in real time. Specifically, the injection head is driven by a two-dimensional precision slide, moving within a range of 5 to 20 mm downstream of the die exit. Its axial position... (Taking the die exit as the origin) From the formula: Confirmed, among which The basic angle between the jet axis and the extrusion axis is set at 45 degrees. During dynamic control, the influence of the extrusion traction speed must be considered. Since the catheter moves forward continuously at a constant traction speed during extrusion molding, aerosol particles require a certain flight time to travel from the nozzle, across the air-assisted flow field, and reach the catheter surface. This flight time can be estimated based on two key parameters: first, the vertical distance the aerosol particles need to traverse, i.e., the corrected expected deposition distance; and second, the average velocity of the aerosol in the multi-layered air-assisted flow field, which can be reasonably estimated based on the average gas velocity of the air-assisted flow field at its characteristic frequency. Specifically, the flight time is approximately equal to the corrected expected deposition distance divided by the average velocity of the aerosol in the flow field.

[0081] To ensure the aerosol accurately hits a specific location on the continuously moving catheter surface, dynamic advance compensation is needed for the circumferential direction of the jet head. The specific implementation is as follows: First, a laser profilometer identifies and obtains in real-time the circumferential azimuth angle corresponding to the weakest area (e.g., the smallest radius) on the current extruded product cross-sectional profile. Second, based on the average radius of the catheter, the current extrusion traction speed, and the calculated flight time, the required circumferential compensation angle is calculated. This compensation angle is calculated by multiplying the extrusion traction speed by the flight time and converting it into the central angle corresponding to the arc the catheter surface rotates through during that flight time. Finally, the calculated circumferential compensation angle is subtracted from the azimuth angle of the weak area measured in real-time by the laser profilometer; the result is the target circumferential position that the jet head should currently be pointing to. By performing the above calculations and adjustments in real-time, the jet direction can be pre-aligned with the weak area of ​​the catheter surface profile that is about to reach the deposition point, effectively compensating for the target point displacement caused by the continuous movement of the catheter and ensuring accurate and uniform deposition of the anti-inflammatory components.

[0082] Simultaneously, the pressure and flow rate of the atomizing medium are controlled. Atomizing gas pressure. Adjust according to the following formula: ;

[0083] in, It is the reference atomization pressure. It is the modulation amplitude coefficient (set to 0.1 to 0.2). It is a preset modulation frequency (e.g., 5 Hz). It is time. This is the atomization cone angle correction calculated in the previous stage. The function of this formula is to apply a sinusoidal modulation to the atomization pressure synchronized with the correction cone angle, causing the ejected aerosol cloud to periodically diffuse and contract in space, thereby dynamically matching the calculated cone angle correction requirements. Finally, through the comprehensive control of the spatial position and atomization parameters, the anti-inflammatory aerosol, guided and constrained by the established multi-layered air-assisted encapsulation flow field, is precisely delivered and deposited onto the surface of the moving catheter melt, achieving uniform in-situ bonding.

[0084] The working principle of this invention is as follows: Taking interventional dual-lumen and triple-lumen urinary catheters as examples, this invention addresses the problems of die swell, deformation, melt fracture, and surface burrs inherent in traditional extrusion by employing precision gas-assisted technology combined with surface anti-inflammatory modification for an integrated solution. The system first uses multiple sensors deployed in the extruder, die, and gas path to synchronously collect melt physical parameters, melt process parameters, and gas process parameters, including external and multiple internal cavity gas-assisted pressures, in real time. Next, based on the collected parameters, a multi-dimensional vector reflecting the multi-cavity structure and process objectives is constructed. Through nonlinear time-series mapping and state reconstruction, a dynamic gas-assisted control mapping table is generated. This table defines the axial pressure gradient of the external gas-assisted layer, the pressure coordination relationship between the gas-assisted layers of each internal cavity, and the precise gas-assisted action sequence. Subsequently, according to this mapping table, the gas pressure of the external main gas-assisted layer and each internal cavity secondary gas-assisted layer is dynamically adjusted in real time and in stages through independently closed-loop controlled gas paths, thereby synchronously forming a uniform and isolated multi-layered gas-assisted encapsulation flow field in the melt circumference and at all internal cavity interfaces. Based on this, the local melt flow rate and overall traction rate within the die are dynamically adjusted according to the flow field pressure fluctuation characteristics to achieve precision extrusion molding. Real-time data on the morphology and surface condition of the product are simultaneously acquired using laser contour scanning and surface finish sensing. Finally, during extrusion, by combining the mapping table and real-time morphology data, the expected deposition distance is calculated and the injection parameters are dynamically corrected to control the injection position, atomization distribution, and circumferential tracking compensation of the anti-inflammatory aerosol. This ensures that the aerosol is deposited in situ and uniformly on the catheter surface during extrusion under the guidance of a multi-layered air-assisted flow field, thereby simultaneously completing the precision molding and surface anti-inflammatory functionalization modification of the catheter.

[0085] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter, characterized in that, include: The process parameter synchronous acquisition module is used to acquire melt physical property parameters, melt process parameters and gas process parameters. The melt process parameters include melt flow rate and melt temperature. The gas process parameters include external gas-assisted pressure and gas-assisted pressure of multiple internal cavities. The dynamic gas-assisted control strategy generation module is used to input melt physical property parameters, melt process parameters and gas process parameters into the co-optimization algorithm for coupled calculation, and generate a dynamic gas-assisted control mapping table that matches the multi-cavity structure. The dynamic gas-assisted control mapping table includes: external gas-assisted layer pressure gradient, pressure coordination relationship of each internal cavity gas-assisted layer and gas-assisted action timing. The multi-layer gas-assisted flow field coordinated control module adjusts the gas pressure of the external gas-assisted layer and each inner cavity gas-assisted layer in real time according to the dynamic gas-assisted control mapping table, and simultaneously forms a uniform and isolated multi-layer gas-assisted encapsulation flow field at the interface of the internal cavity in the circumferential direction of the melt. The precision extrusion and online monitoring module, based on a multi-layer gas-assisted encapsulation flow field, dynamically adjusts the local flow rate of the melt in the die and the overall extrusion traction rate to perform precision extrusion molding of multi-lumen catheters, and simultaneously acquires real-time morphology and surface state data during the extrusion process. The in-situ surface anti-inflammatory modification integrated module is used to regulate the injection position and atomization distribution of anti-inflammatory aerosols based on a dynamic gas-assisted control mapping table and real-time morphology and surface state data during precision extrusion molding, so that the anti-inflammatory aerosols are uniformly deposited on the surface of the catheter under the action of a multi-layer gas-assisted encapsulation flow field.

2. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 1, characterized in that, The generation of the dynamic gas-assisted control mapping table that matches the multi-cavity structure specifically includes: Based on the collected melt physical property parameters, melt process parameters and gas process parameters, a multi-dimensional parameter vector reflecting the multi-cavity structural characteristics and process objectives is constructed. Based on multidimensional parameter vectors, the segmented pressure distribution of the external gas-assisted layer along the axial direction corresponding to each extrusion stage is determined by nonlinear time-series mapping reconstruction, as well as the dynamic pressure ratio between multiple internal gas-assisted layers as the extrusion process progresses. Based on the segmented pressure distribution and dynamic pressure ratio, a dynamic gas-assisted control mapping table is generated that simultaneously includes pressure gradient information, cooperative relationships, and precise temporal relationships.

3. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 2, characterized in that, The method, based on multidimensional parameter vectors and reconstructed through nonlinear time-series mapping, determines the segmented pressure distribution along the axial direction of the external gas-assisted layer corresponding to each extrusion stage, as well as the dynamic pressure ratio between multiple internal cavity gas-assisted layers as the extrusion process progresses. Specifically, this includes: The multidimensional parameter vector is segmented along the extrusion axis to extract key feature vectors corresponding to each extrusion segment. Based on key feature vectors, the pressure reference value required to be maintained by the internal and external gas-assisted layers of each section and the initial pressure ratio between multiple internal cavity gas-assisted layers are determined by reconstructing the state of the extrusion process sequence. Based on the pressure baseline and initial pressure ratio, and combined with the preset flow field equilibrium target, a distribution rule is constructed to map the extrusion time sequence as the segmented pressure distribution of the external gas-assisted layer and the dynamic pressure ratio of the internal gas-assisted layer.

4. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 1, characterized in that, The formation process of the multi-layered air-assisted envelope flow field is as follows: Based on the dynamic gas-assisted control mapping table, in the initial section where the melt enters the die, a main gas-assisted layer is established to enclose the outer periphery of the melt according to the pressure gradient of the external gas-assisted layer. After the main gas-assisted layer is stably established, auxiliary gas is injected into multiple internal cavity channels simultaneously according to the pressure coordination relationship of each internal cavity gas-assisted layer, so that each internal cavity interface forms a secondary gas-assisted layer that matches the pressure of the main gas-assisted layer. Based on the timing of gas-assisted action, the gas pressure of the main gas-assisted layer and each secondary gas-assisted layer is dynamically fine-tuned to ensure that the melt maintains a balanced stress state at all gas-assisted interfaces, forming a multi-layer gas-assisted encapsulation flow field.

5. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 4, characterized in that, The dynamic fine-tuning of gas pressure in the primary gas-assisted layer and each secondary gas-assisted layer based on the timing of gas-assisted action specifically includes: Based on the timing of gas-assisted extrusion, the extrusion process is divided into three consecutive stages: melt filling, preliminary forming, and stabilization. During the melt filling stage, the pressure of the secondary gas-assisted layer is actively matched with the pressure of the primary gas-assisted layer to form initial synergy; In the initial forming stage, with the goal of maintaining the equilibrium of each interface of the melt, the pressure difference between the main gas auxiliary layer and each secondary gas auxiliary layer is calculated and compensated in real time. During the stabilization and finalization stage, the gas pressure of the main gas auxiliary layer and each secondary gas auxiliary layer is adjusted and locked proportionally based on the pressure state after compensation in the previous stage.

6. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 1, characterized in that, The dynamic adjustment of the local flow rate of the melt within the die and the overall extrusion traction rate enables the precision extrusion molding of multi-lumen catheters, while simultaneously acquiring real-time morphology and surface condition data during the extrusion process. Specifically, this includes: Based on the pressure distribution detected in the multi-layer gas-assisted encapsulation flow field, the local velocity adjustment targets for each corresponding region within the die are determined. Based on the local flow velocity adjustment targets of each region, the correction command for the overall extrusion traction rate is calculated collaboratively and output. During the execution of correction instructions, real-time morphology and surface condition data reflecting the outer diameter, roundness, and surface roughness of the product are simultaneously collected by online contour scanning and surface finish sensing units arranged along the extrusion direction.

7. A precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 6, characterized in that, The step of determining the local velocity adjustment target for each corresponding region within the die based on the pressure distribution detected in the multi-layer gas-assisted encapsulation flow field specifically includes: Based on the pressure values ​​of each layer detected synchronously in the multi-layer gas-assisted encapsulation flow field, pressure fluctuation characteristics representing flow stability at the melt-gas interface are extracted. Based on pressure fluctuation characteristics, regions within the exit die associated with the fluctuation characteristics are identified, and the impact of each region on extrusion uniformity is assessed. Based on the degree of influence, the pressure fluctuation characteristics are inversely mapped to the local velocity increase or decrease of the melt in each region to compensate for the non-uniformity of the flow, and the local velocity increase or decrease of the melt is set as the target for local velocity adjustment.

8. The precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 1, characterized in that, The regulation of the injection location and atomization distribution of the anti-inflammatory aerosol specifically includes: Based on the gas-assisted action timing and external gas-assisted layer pressure gradient defined in the dynamic gas-assisted control mapping table, and combined with the preset anti-inflammatory aerosol physical property parameters, the expected deposition path and pattern to be followed in the multi-layer gas-assisted encapsulated flow field are determined. Based on the surface roughness and morphology characteristics of the catheter reflected in the real-time morphology and surface condition data, the expected deposition path and pattern are dynamically corrected to match the actual surface profile of the current extruded product. Based on the modified deposition path and pattern, the circumferential and axial positions of the anti-inflammatory aerosol injection point near the die outlet are adjusted in real time, and the pressure and flow rate of the atomizing medium are controlled simultaneously to achieve in-situ uniform deposition of anti-inflammatory components under the guidance of the air-assisted flow field.

9. A precision air-assisted extrusion molding control system for an interventional multi-lumen medical catheter according to claim 8, characterized in that, The dynamic correction specifically includes: Feature parameters representing changes in surface micro-contours are extracted from real-time morphology and surface state data. The feature parameters are compared with the preset reference profile to calculate and generate a profile deviation vector that represents the deviation between the actual surface and the expected surface. The contour deviation vector is inversely mapped to the aerosol control domain to generate correction instructions for injection angle, atomization cone angle and coverage density to compensate for the deviation. Based on the correction instructions, the control parameters of the deposition path and mode are updated in real time.

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