Three-component composite hollow fiber low-resistance high-efficiency spinning system and control method

Abstract

The present application relates to the technical field of composite hollow fiber production control, in particular to a three-component composite hollow fiber low-resistance high-efficiency spinning system and control method, comprising the following steps: setting the target pressure value of each component; the core control unit delivers three-component melt to the composite spinning box; the pressure sensing module collects the instantaneous pressure value of the three melts at the spinneret inlet in real time; calculating the independent deviation of the instantaneous pressure value of each component melt from the target pressure value; calculating the difference between the instantaneous pressure values of the three-component melts, and identifying the maximum pressure difference; comparing the maximum pressure difference with the maximum pressure deviation threshold; superimposing the independent rotation speed compensation signal on the initial rotation speed setting value of each servo driver to adjust the rotation speed of each extrusion mechanism screw in real time. The present application effectively eliminates the problem of pressure mismatch caused by temperature fluctuations, screw disturbance or material viscosity changes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite hollow fiber production control, and in particular to a three-component composite hollow fiber low-resistance high-efficiency spinning system and control method. BACKGROUND

[0002] Hollow fiber materials are widely used in high-end material fields such as filtration membranes, thermal insulation, medical drug delivery, and multiphase reaction media due to their excellent specific surface area, high porosity, low specific gravity, and controllable structural hierarchy. Hollow fibers are mainly formed by a molding method that combines single-component melt extrusion with central gas or liquid traction to form a hollow cavity. However, their structure and function are relatively simple, making it difficult to meet the increasingly complex functional requirements. Therefore, in recent years, three-component coaxial composite hollow fibers have gradually become a hot research and industrial preparation direction. Existing three-component fiber forming technologies generally use a multi-channel extrusion system to introduce three polymers into different channels, and achieve spatial layering through a multi-layer spinning assembly or a nested nozzle. However, there are still the following problems:

[0003] Before the three melt streams enter the spinneret, the differences in physical parameters such as viscosity, temperature, and flow rate, as well as changes in melt path length and pipe friction, often result in significant inconsistencies in the actual pressures of each component at the spinneret inlet, leading to phenomena such as pressure surges, backflow, and mutual suppression. This causes the fiber cross-section structure to be eccentric and the interlayer to be misaligned, making it difficult to form a symmetrical and uniform hollow structure, resulting in a high rate of defective products.

[0004] Most traditional three-component extrusion systems only use manual or coarse-grained temperature and speed adjustment methods, which cannot achieve real-time monitoring and closed-loop control of the pressure in each channel. Once fluctuations occur in any channel, there is a lack of rapid diagnosis and precise intervention mechanisms, leading to delayed adjustment responses, making it difficult to ensure melt stability, and seriously affecting the stability and winding consistency of fiber continuous formation.

[0005] In summary, the existing three-component composite hollow fiber forming system still has obvious deficiencies in dynamic pressure balance and fine control strategies. SUMMARY

[0006] The present application provides a three-component composite hollow fiber low-resistance high-efficiency spinning system and control method, which integrates a sensing network, real-time feedback control algorithm, and dual-mode regulation mechanism to achieve efficient, low-resistance, and stable composite fiber continuous production process.

[0007] A three-component composite hollow fiber low-resistance high-efficiency spinning system includes a first component extrusion mechanism, a second component extrusion mechanism, a third component extrusion mechanism, a composite spinning box, a blowing cooling device, a traction roller, and a winding device.

[0008] The composite spinning box is internally provided with melt distribution channels in communication with the three extrusion mechanisms respectively; and a concentric three-component composite hollow spinneret plate is mounted at the lower end of the composite spinning box.

[0009] The system further comprises a pressure sensing module, a core control unit and a human-machine interface.

[0010] The pressure sensing module comprises a first component pressure sensor, a second component pressure sensor and a third component pressure sensor arranged at the entrance of the spinneret plate, for collecting the instantaneous pressure values of the melt of each component at the entrance of the spinneret plate in real time.

[0011] The core control unit is electrically connected with the pressure sensing module and the servo drives of the three extrusion mechanisms.

[0012] The human-machine interface is connected with the core control unit, for setting the target pressure values of the melt of each component.

[0013] The core control unit is configured to be capable of executing a control method.

[0014] Optionally, the composite spinning box is an integrated node of three-component melt, internally provided with three melt distribution channels in communication with the three extrusion mechanisms respectively; the melt distribution channels are designed as a heat isolation structure to isolate the thermal interference between the components; and each melt distribution channel converges into a concentric circle structure in the final space above the spinneret plate, so that the three components are compounded into a coaxial arrangement in space.

[0015] Optionally, the air blowing cooling device is arranged below the spinneret plate, to apply a directional and temperature-controllable air flow to the nascent fiber to form a cooling and solidification environment; and the cooling air duct is arranged in a ring-shaped symmetrical layout.

[0016] A control method of a system for controlling the three-component composite hollow fiber low-resistance high-efficiency spinning system, comprising the following steps:

[0017] comprising the following steps:

[0018] S1: setting the target pressure values of the first component melt, the second component melt and the third component melt at the entrance of the spinneret plate through the human-machine interface, and setting a maximum pressure deviation threshold value between the components;

[0019] S2: the core control unit drives the first extrusion mechanism, the second extrusion mechanism and the third extrusion mechanism to start, to deliver the three-component melt to the composite spinning box, and after distribution through the melt distribution channels, to reach the entrance of the spinneret plate;

[0020] S3: the pressure sensing module collects the instantaneous pressure values of the three melts at the entrance of the spinneret plate in real time, which are respectively and transmit the instantaneous pressure value to the core control unit;

[0021] S4: the core control unit calculates the independent deviation of each component melt instantaneous pressure value from the target pressure value;

[0022] S5: the core control unit calculates the difference between the instantaneous pressure values of the three-component melt, and identifies the maximum pressure difference value;

[0023] S6: the core control unit compares the maximum pressure difference value with the maximum pressure deviation threshold value ;

[0024] If , the core control unit generates independent rotation speed compensation signals for the first, second and third extrusion mechanisms according to the independent deviation , using a PID control algorithm ;

[0025] If , the core control unit starts the cooperative pressure balance mode, and preferentially applies reverse linkage rotation speed compensation signals to the extrusion mechanisms corresponding to the highest and lowest pressures, to quickly reduce the maximum pressure difference value;

[0026] S7: the core control unit superimposes the generated independent rotation speed compensation signals on the initial rotation speed set value of each servo driver, to adjust the rotation speed of each extrusion mechanism screw in real time;

[0027] S8: through the rotation speed adjustment of S7, the output flow of the corresponding component melt is changed, so that the pressure values of each melt reaching the spinneret inlet tend to their respective target pressure values , and the pressure difference between components is ensured to be less than the set threshold value;

[0028] S9: when the instantaneous pressure value is stable within the allowable fluctuation range of the target pressure value, and the maximum pressure difference value is continuously stable within the maximum pressure deviation threshold value , the three-component melts are compounded at the spinneret inlet with stable pressure and flow relationship, and are extruded through the spinneret holes to form primary fibers;

[0029] S10: after the primary fibers are solidified by the air blowing cooling device, they are drawn by the traction roller and finally collected by the winding device, completing the low-resistance high-efficiency fiberizing process.

[0030] Optionally, the pressure sensing module comprises:

[0031] Multiple pressure sensors: respectively installed at the end of the melt channel of the first component, the second component and the third component, close to the entrance of the spinneret;

[0032] Data acquisition interface: including analog / digital output port, for communication with the core control unit;

[0033] The pressure sensor adopts one of a diaphragm type strain gauge, a piezoresistive type or a micro-capacitive type pressure sensor.

[0034] Optionally, in S6: when the core control unit determines that the maximum pressure difference value is less than or equal to the maximum pressure deviation threshold, enter the independent control mode, and input three independent deviation amounts into three independent digital PID controllers respectively; each PID controller performs operation according to preset proportional coefficient, integral time and differential time parameters, and independently outputs an independent rotation speed compensation signal for real-time adjustment of the rotation speed of the three extrusion mechanisms.

[0035] Optionally, in S6: when the core control unit determines that the maximum pressure difference value is greater than the maximum pressure deviation threshold, enter the cooperative pressure balance mode; the core control unit identifies the highest and lowest two components in the current instantaneous pressure value, calculates the unbalanced pressure difference therebetween, and inputs the unbalanced pressure difference into a high proportional coefficient PID controller for balance adjustment, and outputs a linkage compensation amount.

[0036] Optionally, the cooperative pressure balance mode further comprises applying the linkage compensation amount to the extrusion mechanism corresponding to the component with the highest pressure in a deceleration mode and to the extrusion mechanism corresponding to the component with the lowest pressure in an acceleration mode, so as to quickly compress the pressure difference between the two.

[0037] Optionally, S6 further comprises that for the pressure component in the middle, the corresponding extrusion mechanism keeps the current rotation speed unchanged or uses the adjustment value of the last period until the pressure difference is restored to the allowable range and the cooperative mode is exited.

[0038] Optionally, the superposition operation chain in S7 comprises:

[0039] The core control unit outputs an adjustment instruction;

[0040] The adjustment instruction is sent to the servo driver of each extrusion mechanism in the form of a digital signal through a communication protocol;

[0041] After receiving the new adjustment instruction, the servo driver updates the output rotation speed of the motor;

[0042] The motor drives the screw to generate a new rotation speed, thereby adjusting the extrusion speed of the corresponding polymer melt.

[0043] The beneficial effects of the present application are:

[0044] The application realizes coaxial guiding and physical isolation of different melts in space by designing three-component independent extrusion mechanism, concentric composite spinneret and multi-channel melt distribution system, so that the three polymers can be compounded in the spinneret hole in a concentric and stable manner. Especially, independent pressure sensors are arranged at the spinneret inlet, and combined with precise pressure control logic, the problems such as structural eccentricity and interlayer separation caused by uneven flow or disturbance are effectively inhibited, and the interface consistency, coaxiality and finished product quality stability of the composite fiber are improved.

[0045] The application introduces two control strategies of "independent precise regulation mode" and "cooperative pressure balance mode", and sets clear mode switching conditions. When the pressure is stable, the PID algorithm is used to adjust the three melts respectively to maintain high-precision control. When serious pressure imbalance occurs, the main contradictory components are quickly identified, and the high-efficiency pressure difference is suppressed through the reverse linkage compensation mechanism, which not only has local regulation accuracy, but also has overall response speed, forming an intelligent closed-loop "monitoring-judgment-intervention-recovery" dynamic control system.

[0046] The application forms a complete structure, a closed logic, and a fast response composite fiber spinning system from melt feeding, composite flow guiding, pressure regulation to spinning, cooling and solidification, and traction winding. Especially in the dynamic regulation process, the melt flow can be corrected in real time, effectively eliminating the pressure mismatch problem caused by temperature fluctuations, screw disturbance or material viscosity changes, ensuring that the cavity structure of the fiber remains continuous and the inner wall thickness is stable in the entire forming path. Compared with the traditional scheme, the pressure loss and spinning failure rate are reduced, and the industrial adaptability and product consistency guarantee capability are stronger. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only illustrate the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0048] Figure 1 It is a spinning system schematic diagram of the embodiment of the application.

[0049] Figure 2 It is a double-mode regulation schematic diagram of the embodiment of the application. DETAILED DESCRIPTION

[0050] The application will be described in detail below with reference to the drawings and specific embodiments, and other alternative ways can also be implemented by those skilled in the art; and the drawings are only used to more specifically describe the embodiments, and are not intended to specifically limit the application.

[0051] As shown in the drawings, Figure 1 A three-component composite hollow fiber low-resistance high-efficiency spinning system includes a first component extrusion mechanism, a second component extrusion mechanism, a third component extrusion mechanism, a composite spinning beam, a blowing cooling device, a traction roller and a winding device.

[0052] The composite spinning beam is internally provided with a melt distribution channel in communication with the three extrusion mechanisms; and a concentric three-component composite hollow spinneret is mounted at the lower end of the composite spinning beam.

[0053] The system further includes a pressure sensing module, a core control unit and a man-machine interface, wherein:

[0054] The pressure sensing module includes a first component pressure sensor, a second component pressure sensor and a third component pressure sensor arranged at the entrance of the spinneret, for real-time acquisition of the instantaneous pressure values of the melt of each component at the entrance of the spinneret.

[0055] The core control unit is electrically connected with the pressure sensing module and the servo drivers of the three extrusion mechanisms.

[0056] The man-machine interface is connected with the core control unit, for setting the target pressure values of the melt of each component.

[0057] The core control unit is configured to be executable to control the method.

[0058] 1. The first component extrusion mechanism, the second component extrusion mechanism and the third component extrusion mechanism: the three-component extrusion mechanisms are respectively used for heating, plasticizing and stably extruding the polymer melts of three different properties from independent feeding systems by screw conveying. The three components can form the inner layer, the middle layer and the outer layer structure of the fiber according to the functional requirements, and can also be used to form the core layer, the cladding layer and the hollow cavity wall of the fiber.

[0059] The first component extrusion mechanism: can be used to supply the structural skeleton component;

[0060] The second component extrusion mechanism: can be used to supply the functional coating component, such as hydrophilic, hydrophobic and high-barrier polymer;

[0061] The third component extrusion mechanism: can be used to supply the material required to form the hollow cavity structure of the fiber, or to provide an auxiliary mechanical reinforcing layer.

[0062] The screw rotation speed, temperature section heating parameters and back pressure adjusting device of each extrusion mechanism can be set to ensure that different melt viscosities and rheological properties are optimized respectively.

[0063] 2. The composite spinning beam is an integrated node of three-component melt, and is provided with a plurality of independent melt channels. The structural characteristics are as follows:

[0064] The internal three-melt distribution flow channels are respectively communicated with the three extrusion mechanisms;

[0065] The melt distribution flow channels are designed as a heat isolation structure to avoid thermal interference between the components;

[0066] The channels converge into a concentric circle structure in the final space above the spinneret plate, so as to ensure that the three components are compounded into a coaxial arrangement in space.

[0067] 3. The spinneret plate is a key structural part installed at the lower end of the composite spinning beam, and the spinneret hole structure is a three-component concentric circle composite hollow hole type, including a center hole, an annular middle layer channel and an outermost layer channel.

[0068] The three melts are sequentially coated from the inside to the outside, and dynamic coaxial compounding is realized in the spinneret hole.

[0069] The spinneret plate is made of corrosion-resistant alloy, and the hole diameter and channel cross section can be made according to the fiber size.

[0070] This structure realizes the synchronous extrusion, coaxial compounding and hollow structure formation of the three components during the spinning process, and is the core component for realizing the performance of the fiber.

[0071] 4. The air blowing cooling device is arranged below the spinneret plate, and its main functions are as follows: applying constant, directional and temperature-controllable air flow to the nascent fiber to form a rapid cooling and solidification environment; adjusting the air speed and temperature to control the fiber shrinkage rate, solidification speed and cross-sectional shape quality.

[0072] The cooling air duct is arranged in a ring-shaped symmetrical layout to ensure that the concentric hollow structure of the fiber does not deviate due to uneven cooling. Through this device, the fiber forming time can be significantly shortened, the overall spinning line speed can be improved, and the size stability of the fiber product can be enhanced.

[0073] 5. The traction roller is arranged after the air blowing cooling zone to stabilize the tension of the cooled nascent fiber, and the line speed control ensures the output length per unit time; the traction force is adjustable to adapt to different fiber linear density, stiffness and other physical properties; the surface treatment of the traction roller has anti-adhesion, anti-skid and wear-resistant properties to protect the fiber from damage during the traction process.

[0074] 6. The winding device is the terminal module of the whole spinning process, which continuously winds and collects the shaped fibers after traction, and can realize two winding modes of constant tension or constant linear speed, and is configured with automatic roll changing and tension control to adapt to continuous high-speed production.

[0075] 7. The pressure sensing module monitors the dynamic pressure state of each component melt at the entrance of the spinneret in real time, mainly including:

[0076] Three high-precision pressure sensors are arranged at the connection port of the three melt channels and the spinneret respectively;

[0077] The sensor can collect instantaneous pressure fluctuation to meet the requirements of high-speed spinning on control feedback;

[0078] The collected data is transmitted to the subsequent control in real time for executing the subsequent control strategy.

[0079] 8. The core control unit is the intelligent core of the application, and the main functions include:

[0080] Receiving data input from the pressure sensing module;

[0081] Carrying out difference calculation on the target pressure value and the real-time pressure value of the three components;

[0082] Executing PID algorithm or linkage control algorithm to output servo speed compensation signal;

[0083] Adjusting the screw speed of the three extrusion mechanisms to realize feedback closed-loop control.

[0084] The control unit is realized by an industrial-grade embedded control board card or PLC control.

[0085] 9. The man-machine interface is the interface for user operation and control unit interaction, which can set target pressure value, maximum tolerance deviation, control mode and other parameters, and display process state information such as component pressure, speed, flow rate in real time, and is connected and integrated with the upper industrial control system.

[0086] As shown in Figure 2 A control method for controlling the above spinning system, comprising the following steps:

[0087] S1: Through the man-machine interface, set the target pressure values of the first component melt, the second component melt and the third component melt at the entrance of the spinneret as , and set a maximum pressure deviation threshold between components ;

[0088] In the process of melt composite spinning, different components of polymer usually have different physical properties, such as melt viscosity, thermal stability, crystallization behavior and surface tension, etc. These differences will directly affect the flow behavior and composite interface morphology at the entrance of the spinneret, therefore, the pressure of each melt before entering the spinneret must be set independently to achieve the following purposes:

[0089] Ensure that the three melts achieve coaxial symmetric distribution in space, avoid local pressure too high or too low, causing the melt to deviate in the spinneret hole, resulting in fiber structure eccentricity or fault.

[0090] Match the flow resistance design of each annular channel of the spinneret, realize smooth passing of the melt in different channels at appropriate flow rate, prevent local over-flow or stagnation.

[0091] Form a stable composite interface tension, ensure good interface bonding, prevent delamination or melt interpenetration.

[0092] Provide a target reference signal for the PID controller to build the "ideal state" in the subsequent adjustment strategy.

[0093] Therefore, S1 inputs through the human-machine interface , defines the "expected state" of the three-component melt before compounding, which is one of the control references.

[0094] The above setting operation is completed based on the human-machine interface (HMI), which is the information bridge between the operator and the system control logic.

[0095] In addition to setting the target pressure values of the three components, the user is also required to set an additional parameter, the maximum allowed pressure deviation threshold between components. This value defines the maximum acceptable pressure imbalance tolerance interval between components. If the pressure difference between any two components exceeds this threshold, it is easy to cause fiber cross-section imbalance during spinning, which will damage the stability of compounding. The subsequent control compares the pressure difference between any two melts with the threshold to determine whether to switch from independent PID adjustment mode to coordinated control mode. This parameter is determined based on the equipment experience value and the rheological test results under actual working conditions, and is generally set between 0.05 MPa and 0.3 MPa.

[0096] By introducing the double-layer setting mechanism of "three-component independent target pressure + maximum deviation threshold", compared with the traditional multi-channel control, this scheme clearly distinguishes between "target state constraints" (pressure setting) and "deviation tolerance boundary" (maximum deviation).

[0097] Provide a double-factor judgment standard for the control unit to realize dynamic switching of the adaptive control strategy.

[0098] Build a "quantitative structure forming standard" to avoid relying on experience judgment;

[0099] The complex structure of hollow, composite, asymmetric multi-layer fibers requires effective adaptation.

[0100] S2: The core control unit drives the first extrusion mechanism, the second extrusion mechanism, and the third extrusion mechanism to start, and transports the three-component melt to the composite spinning beam, and after distribution through the melt distribution channel, reaches the entrance of the spinneret. In the control of the three-component composite hollow fiber spinning system of the present application, S2 plays a key role in converting the target pressure setting into actual melt delivery behavior, marking the transition from the static parameter configuration phase to the dynamic feeding execution phase, and is the initial synchronous delivery process before the multi-component fluid realizes coaxial compounding. The core task of S2 step is to start the three extrusion mechanisms, so that the three polymer melts with different physical properties are heated, plasticized, and sent into the composite spinning beam under servo control. The three melts flow in the set path in the beam body and are delivered downward in an independent but coordinated manner through the internal melt distribution channel, and finally converge at the entrance of the spinneret, providing a feeding basis for the subsequent formation of a concentric composite structure.

[0101] The starting process of each extrusion mechanism is as follows:

[0102] After the core control unit receives the target pressure value set in S1, it sends a start signal to the servo drive of each extrusion mechanism through its internal control logic module (PLC program or embedded control algorithm). Each extrusion mechanism is composed of the following components:

[0103] Barrel and heating section: melt the solid raw materials (such as particles or powders);

[0104] Screw mechanism: deliver the melted polymer to the outlet end in a stable linear propulsion manner;

[0105] Pressure regulating section or melt metering pump: regulate the melt delivery speed to maintain stable pressure output;

[0106] Temperature controller: maintain uniform temperature in each section to avoid overheating or condensation.

[0107] Each extrusion mechanism operates independently, and its output flow can be adjusted according to the target pressure and current deviation. At the initial stage of starting, the three extrusion mechanisms operate at the initial set speed to ensure orderly and synchronized starting.

[0108] After the three-component melts are pushed by the extrusion mechanisms, they are respectively introduced into the composite spinning beam through independent high-temperature heat preservation pipelines. The composite spinning beam is a key unit for pre-orientation positioning and coaxial arrangement of the melts in space, and has a central flow channel convergence structure inside. The three melts are guided to the "central hole", "middle ring hole", and "outer ring hole" structures on the spinneret from three-dimensional space, realizing concentric guidance in physical position.

[0109] At this stage, although the three melts have not yet contacted, the pre-alignment of the spatial path has been achieved, which is a prerequisite for the subsequent coaxial composite and hollow forming in the spinneret.

[0110] The melt distribution channel is the key structure of the internal structure of the composite spinning beam, which is a collection of independent channels guiding the flow of three melts to the entrance of the spinneret. In the last section of the channel near the spinneret, the melts need to be introduced into the concentric hole structure on the spinneret to maintain physical alignment without layering or mixing.

[0111] The end point of S2 is when the three melts are delivered to the entrance of the spinneret. At this node, the state of the three melts should meet the following conditions:

[0112] Flow stability: the pressure of each melt is near the target value with small fluctuation amplitude;

[0113] Temperature uniformity: the temperature of the melt is consistent everywhere to avoid abnormal interfacial tension;

[0114] Spatial alignment: each melt is strictly aligned with the corresponding central hole, middle ring hole and outer ring hole in the spinneret structure;

[0115] No contact or mixing: before entering the spinneret, the three melts remain in a state of spatial isolation.

[0116] This state can be regarded as a "pre-critical state before composite", and its stability directly affects the interface stability and structural consistency in the initial stage of fiber forming.

[0117] Through strict control and channel structure, the spatial orientation of the three-component melt is realized, ensuring the symmetry of the initial conditions of subsequent coaxial composite spinning; a physical isolation and thermal stability structure is established to avoid component interference.

[0118] S3: The pressure sensing module collects the instantaneous pressure values of the three melts at the entrance of the spinneret, which are and transmits the instantaneous pressure values to the core control unit; the pressure sensing module monitors the pressure state of the three melts at the entrance of the spinneret in high frequency, real-time and independently, and accurately transmits the collected results to the core control unit without delay, providing accurate feedback basis for subsequent adjustment calculation;

[0119] In the forming process of composite fibers, the pressure state of the three melts at the entrance of the spinneret directly determines the matching degree of the flow rate of each component melt, the coaxiality of the fiber cross-section and the stability of the hollow structure; therefore, the pressure state at this node must be measured and used as the main feedback parameter of the core control unit. The pressure sensing module consists of the following parts:

[0120] 1. Three high-precision pressure sensors: installed at the end of the melt channel of the first component, the second component, and the third component, respectively, close to the entrance of the spinneret. Each sensor works independently to ensure that the pressure value of each melt can be collected separately. To prevent the high-temperature melt from causing thermal drift to the sensor, the sensor is fixed by a high-temperature support and supplemented with a thermal isolation structure.

[0121] 2. Data acquisition interface: including analog / digital output port or bus communication module, used for communication with the core control unit.

[0122] 3. The sensor type adopts a diaphragm strain gauge, piezoresistive, or micro-capacitive pressure sensor, which has good high-temperature resistance.

[0123] The pressure sensor of each channel works continuously during operation and samples the pressure at fixed time intervals to generate real-time pressure value signals.

[0124] First component instantaneous pressure value:

[0125] Second component instantaneous pressure value:

[0126] Third component instantaneous pressure value:

[0127] These values are collected in digital form and have a timestamp to support trend analysis or dynamic response based on time series.

[0128] The three collected pressure values are sent in real time to the core control unit through the communication interface. The control unit, as the central device for executing control logic, compares these pressure values with the previously set target pressure values.

[0129] S4: The core control unit calculates the independent deviation of the instantaneous pressure value of each component melt from the target pressure value By comparing the real-time collected instantaneous pressure value of the melt with the preset target pressure value one by one through the core control unit, the current pressure deviation of each component is obtained, which provides accurate judgment basis for subsequent PID adjustment or cooperative linkage control.

[0130] In the spinning process of three-component composite fibers, the pressure value of each component determines its flow rate and wrapping position in the spinneret hole. Due to factors such as screw output disturbance, material viscosity fluctuation, and temperature change during processing, the actual melt pressure value of each component is often difficult to stabilize at the ideal set value for a long time. Therefore, the deviation between the current actual pressure value and the target pressure value must be calculated, and the following judgment is made:

[0131] Whether each component needs to be adjusted at present; ​​​

[0132] the direction of the adjustment (speed up or slow down);

[0133] whether the magnitude of the adjustment exceeds the allowed range;

[0134] The S4 calculation step actually constitutes the error signal generator of the control unit.

[0135] Two groups of variables are involved:

[0136] : the target pressure value set by the operator during the system initialization phase, representing the ideal steady-state pressure that the melt of each component is expected to reach at the entrance of the spinneret;

[0137] : the current melt pressure value collected in real time by the pressure sensing module, reflecting the pressure output under actual operating conditions.

[0138] By calculating the difference between the two, the pressure deviation of each component is calculated and expressed as:

[0139] ; where, ;

[0140] i.e., respectively calculate:

[0141] ;

[0142] ;

[0143] ;

[0144] This calculation is performed in the processing chip of the core control unit, and can complete multiple iterations per second, supporting high-frequency dynamic response.

[0145] The deviation value is not just a numerical difference, its positive or negative sign also has a clear physical meaning:

[0146] If indicates that the current melt pressure is lower than the target value, indicating that the screw output flow is insufficient or the downstream flow resistance is too large, at this time the screw speed of the extrusion mechanism of this path needs to be increased;

[0147] If indicates that the current pressure is higher than the target value, which may be due to excessive flow in this path or insufficient flow in the other two paths, at this time the screw speed of this path needs to be reduced;

[0148] If indicates that this component has reached a state close to the target, and the current speed can be maintained.

[0149] S5: The core control unit calculates the difference between the instantaneous pressure values of the three-component melt, and identifies the maximum pressure difference ; this value is not an absolute deviation, but a quantitative expression of the "difference between the three components", which is directly used to determine whether the control mode needs to be switched from the conventional independent PID control to the coordinated pressure linkage control. It is the key point of the entire control method to realize the pressure balance stability judgment mechanism. The principle, function, calculation method and implementation significance are explained in detail below.

[0150] In the control of multi-component composite spinning, only calculating the deviation between each component and its target value is not enough to reflect the stability of the overall system. For example, the three-way melt may deviate from the target value at the same time, but the difference between them is small, which can still be considered as a balanced system. On the contrary, even if the deviation is small, but the difference between them is large (one high and one low), it is likely to cause the fiber structure to be damaged at the spinning point. Therefore, it is necessary to introduce a relative pressure difference judgment mechanism between the three-component melt to monitor the "coordination" of the overall system rather than just "accuracy".

[0151] Calculate the absolute pressure difference between the following three groups:

[0152] 1. The difference between the first component and the second component: ;

[0153] 2. The difference between the second component and the third component: ;

[0154] 3. The difference between the first component and the third component: ;

[0155] Among the above three, take the maximum value, defined as: ; this value reflects the most serious pressure inconsistency among the three components.

[0156] S6: The core control unit compares the maximum pressure difference with the maximum pressure deviation threshold :

[0157] If , the core control unit generates an independent speed compensation signal for the first, second and third extrusion mechanisms according to the independent deviation ;

[0158] If , the core control unit starts the coordinated pressure balance mode, and applies a reverse linkage speed compensation signal to the extrusion mechanism corresponding to the highest and lowest component to quickly reduce the maximum pressure difference;

[0159] Specifically as follows:

[0160] [Mode one] independent precision control mode: when the maximum pressure difference between the three components melt is detected within the tolerable range, that is: ; the core control unit enters the independent precision control mode, and executes the following control strategy:

[0161] S61. respectively, each way independent deviation , , Input to three independent digital PID controller;

[0162] S62. each PID controller according to the preset parameters for standard PID operation, calculate their respective speed compensation: ;

[0163] Among them, The independent speed compensation signal of the first Extrusion mechanism, The pressure deviation of the first Component melt, The proportional coefficient, integral time coefficient, differential time coefficient respectively;

[0164] S63. The obtained Superimposed on the current extrusion mechanism screw base speed setting value, complete independent precision flow regulation.

[0165] [Mode two] collaborative pressure balance mode: when it is detected that there is a significant pressure imbalance between the components, that is: ; the core control unit immediately enters the collaborative pressure balance mode, and executes the following rapid adjustment mechanism:

[0166] S64. From the three components, identify the two unbalanced boundary components with the highest and lowest pressure values, respectively:

[0167] ;

[0168] ;

[0169] S65. Calculate the current imbalance pressure difference: ; wherein, The current imbalance pressure difference is used to drive the linkage compensation, Indicates the maximum and minimum value in the current instantaneous pressure value.

[0170] S66. Take As an input signal, input to a high proportional coefficient PID controller specially used for imbalance adjustment, and output a basic linkage adjustment amount:

[0171] ;

[0172] wherein, represents the base linkage compensation amount, represents the enhanced PID control parameter in the collaborative control mode, in particular , to ensure fast response.

[0173] S67. Reverse linkage compensation: the control unit applies the following reverse linkage adjustment to the two extrusion mechanisms with the highest and lowest pressures, respectively:

[0174] to the corresponding extrusion mechanism: ;

[0175] to the corresponding extrusion mechanism: ;

[0176] wherein, represents the linkage gain coefficient, further amplifying the linkage adjustment effect and improving the dynamic response efficiency. The adjustment direction ensures "high pressure deceleration and low pressure acceleration" to compress the pressure difference value in the fastest path, represents the screw speed adjustment signal corresponding to the current highest pressure component, adjusted negatively by the control unit, represents the screw speed adjustment signal corresponding to the current lowest pressure component, adjusted positively by the control unit.

[0177] S68. Processing of intermediate pressure components: for the third component (i.e. the component with pressure value between and ), the core control unit keeps its current compensation unchanged:

[0178] ; represents the intermediate component corresponding to the pressure value between high and low, and the control strategy is to make no adjustment or keep the effective value of the last period, avoiding unnecessary disturbance when performing linkage adjustment, maintaining the symmetry of the system structure and the focus of the control strategy.

[0179] S69. The control unit continuously performs linkage adjustment and real-time monitoring of new , once:

[0180] ; that is, the imbalance state is resolved, automatically exiting the collaborative pressure balance mode and returning to the normal independent precise control mode, reusing the individual PID independent control strategy for regular fine-tuning.

[0181] S7: The core control unit will generate an independent speed compensation signal The initial rotation speed setting value of each servo driver is superimposed to adjust the rotation speed of the screw of each extrusion mechanism in real time.

[0182] S7 is the operation of the control flow from "calculation complete" to "physical execution", that is, the rotation speed compensation signal of each component extrusion mechanism output by the core control unit is formally superimposed on the original basic setting value and acts on the servo drive system in real time, so as to realize the dynamic regulation and control of the melt pressure. In S6, the core control unit has calculated three rotation speed compensation values according to the pressure deviation of each component melt. At this time, these compensation values only exist in the algorithm output end of the controller, and S7 applies the results to the device level to drive the corresponding screw rotation speed to change, thereby adjusting the output flow of each melt to form the actual physical response of the control.

[0183] The servo driver of each extrusion mechanism has set a basic rotation speed value at the initial start to provide an initial feed flow. After detecting the deviation, a dynamic compensation signal representing the adjustment amount to be made on the basic rotation speed will be generated. The "superimposition" mentioned in S7 is to combine the compensation signal with the original setting value to form a new real-time running rotation speed. This superimposition operation is completed through numerical coverage or dynamic incremental adjustment. The controller updates the target rotation speed of the driver to make the actual output of the screw consistent with the adjustment instruction. During the operation, with the continuous change of the real-time deviation, this superimposition update operation will occur frequently to realize continuous fine tuning of the process. The whole operation chain includes:

[0184] The core control unit outputs the adjustment instruction;

[0185] The instruction is sent to the servo driver in the form of a digital signal through a communication protocol;

[0186] After receiving the new instruction, the driver updates the output rotation speed of the motor;

[0187] The motor drives the screw to produce a new rotation speed, thereby adjusting the extrusion speed of the corresponding polymer melt.

[0188] S8: Through the rotation speed adjustment of S7, the output flow of the corresponding component melt is changed, thereby making the pressure values of each melt reaching the spinneret inlet tend to their respective target pressure values , and ensuring that the pressure difference between components is less than the set threshold; through the adjustment of the rotation speed of the extrusion mechanism in S7, the output flow of each component melt is changed, thereby directly affecting the actual melt pressure value at the entrance of the spinneret, making it gradually approach the set target pressure value. The increase or decrease of the flow of each component will cause the corresponding pressure to rise or fall, realizing accurate regulation and control. At the same time, through the coordinated adjustment of the three flows, the pressure difference between the components can be effectively compressed to keep it within the allowed set threshold, thereby ensuring the stability and concentricity requirements of the composite fiber structure.

[0189] S9: When the actual pressure values of the three melt streams are stabilized in the respective target pressure ranges by continuous control, and the maximum pressure difference between them is always kept within the preset allowable range, it indicates that the feeding system has reached a dynamic balance state. At this time, the three-component melt streams converge at the spinneret inlet with relatively constant and coordinated pressure and flow rate, and can stably achieve spatial coaxial compounding, synchronously extrude from the spinneret holes, and form primary fibers with complete structure and uniform interface. This state marks that the regulation process has entered a stable operation stage, and has the ability to continuously output high-quality composite hollow fibers. That is, when the instantaneous pressure values are stabilized within the allowable fluctuation range of the target pressure values, and the maximum pressure difference value is continuously stabilized within the maximum pressure deviation threshold , the three-component melt streams are compounded at the spinneret inlet with stable pressure and flow rate relationship, and extruded from the spinneret holes to form primary fibers.

[0190] S10: After extrusion, the primary fibers first pass through the air blowing cooling device to make them quickly solidify and maintain stable composite structure and hollow form, then the fibers are continuously output by the traction roller with constant tension to ensure the stability of their linear density and diameter, finally the formed fibers are uniformly collected by the winding device, completing the entire low-resistance high-efficiency fiber forming process and providing conditions for subsequent storage, processing or application.

[0191] The present application encompasses any substitutions, modifications, equivalent methods and solutions made on the essence and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be fully understood without these details by those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits, etc. are not described in detail.

[0192] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A control method of a three-component composite hollow fiber low-resistance high-efficiency spinning system, characterized by, The system comprises a first component extrusion mechanism, a second component extrusion mechanism, a third component extrusion mechanism, a composite spinning beam, a blowing cooling device, a traction roller and a winding device; The composite spinning beam is internally provided with melt distribution channels in communication with the three extrusion mechanisms respectively; and a concentric three-component composite spinneret is mounted at the lower end of the composite spinning beam; The system further comprises a pressure sensing module, a core control unit and a man-machine interface, wherein: The pressure sensing module comprises a first component pressure sensor, a second component pressure sensor and a third component pressure sensor arranged at the inlet of the spinneret, for collecting the instantaneous pressure values of the melt of each component at the inlet of the spinneret in real time; The core control unit is electrically connected with the pressure sensing module and the servo drives of the three extrusion mechanisms; The man-machine interface is connected with the core control unit, for setting the target pressure values of the melts of each component; The core control unit is configured to execute a control method; The control method comprises the following steps: S1: setting, through the human-computer interaction interface, a target pressure value of the first component melt, the second component melt and the third component melt at the entrance of the spinneret, and setting a maximum pressure deviation threshold value allowed between the components ; S2: The core control unit drives the first component extrusion mechanism, the second component extrusion mechanism and the third component extrusion mechanism to start, and the melts of the three components are delivered to the composite spinning beam, distributed through the melt distribution channels and then reach the inlet of the spinneret; S3: The pressure sensing module collects the instantaneous pressure values of the melts of the three components at the inlet of the spinneret in real time, and transmits the instantaneous pressure values to the core control unit; S4: The core control unit calculates the independent deviation amount of the instantaneous pressure values of the melts of each component from the target pressure values; S5: the core control unit calculates the difference between each pair of the three-component melt instantaneous pressure values, and identifies the maximum pressure difference value ; S6: The core control unit compares the maximum pressure difference value with the maximum pressure deviation threshold value ​ If If the independent deviation is greater than 0, the core control unit generates a first component extrusion mechanism, a second component extrusion mechanism, and a third component extrusion mechanism servo driver independent rotation speed compensation signal according to the independent deviation. If If the core control unit starts the cooperative pressure balance mode, it gives priority to the extrusion mechanism corresponding to the component with the highest and lowest pressure to apply a reverse linkage speed compensation signal to quickly reduce the maximum pressure difference. S7: The core control unit superimposes the generated independent rotation speed compensation signal on the initial rotation speed setting value of each servo drive, and adjusts the rotation speed of the screw rod of each extrusion mechanism in real time; S8: Through the rotation speed adjustment of S7, the output flow of the corresponding component melt is changed, so that the pressure values of each melt reaching the inlet of the spinneret tend to their respective target pressure values, and the pressure difference between the components is ensured to be less than a set threshold value; S9: When the instantaneous pressure values are stable within the allowable fluctuation range of the target pressure values, and the maximum pressure difference value is continuously stable within the maximum pressure deviation threshold value, the melts of the three components are compounded at the inlet of the spinneret with stable pressure and flow relationship, and are extruded through the spinneret holes to form the primary fibers; S10: After the primary fibers are solidified by the blowing cooling device, they are drawn by the traction roller and finally collected by the winding device, completing the low-resistance high-efficiency fiberizing process.

2. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, The composite spinning beam is the integration node of the three-component melts, internally provided with three melt distribution channels in communication with the three extrusion mechanisms respectively; the melt distribution channels are designed as a heat isolation structure to isolate the thermal interference between the components; and the melt distribution channels converge into a concentric structure in the final space above the spinneret, so that the three components are compounded into a coaxial arrangement in space.

3. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, The blowing cooling device is arranged below the spinneret, applies a directional and temperature-controllable air flow to the primary fibers to form a cooling and solidification environment; and the cooling air duct is arranged in a ring-shaped symmetrical layout.

4. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, The pressure sensing module comprises: Multiple pressure sensors: respectively installed at the end of the melt channel of the first component, the second component, and the third component, close to the entrance of the spinneret; Data acquisition interface: including analog / digital output port, for communication with the core control unit; The pressure sensor adopts one of the following: diaphragm strain gauge, piezoresistive or micro-capacitive pressure sensor.

5. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, In S6, when the core control unit determines that the maximum pressure difference is less than or equal to the maximum pressure deviation threshold, it enters the independent control mode, and inputs the three independent deviation values into three independent digital PID controllers respectively; each PID controller performs operation according to the preset proportional coefficient, integral time and differential time parameters, and independently outputs an independent speed compensation signal for real-time adjustment of the screw speed of the three extrusion mechanisms.

6. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, In S6, when the core control unit determines that the maximum pressure difference is greater than the maximum pressure deviation threshold, it enters the cooperative pressure balance mode; the core control unit identifies the highest and lowest two components among the current instantaneous pressure values, calculates the unbalanced pressure difference between them, and inputs the unbalanced pressure difference into a high proportional coefficient PID controller for balance adjustment, and outputs a linkage compensation amount.

7. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 6, characterized in that, The cooperative pressure balance mode also includes applying the linkage compensation amount to the extrusion mechanism corresponding to the component with the highest pressure in a deceleration mode, and to the extrusion mechanism corresponding to the component with the lowest pressure in an acceleration mode, to quickly compress the pressure difference between them.

8. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 7, characterized in that, S6 also includes that for the pressure component in the middle, the corresponding extrusion mechanism keeps the current speed unchanged or uses the adjustment value of the last period until the pressure difference returns to the allowable range and exits the cooperative pressure balance mode.

9. The control method of a three-component composite hollow fiber low- resistance high-efficiency spinning system according to claim 1, characterized in that, The superposition operation chain in S7 includes: The core control unit outputs the adjustment instruction; The adjustment instruction is sent to the servo driver of each extrusion mechanism in the form of a digital signal through a communication protocol; After receiving the new adjustment instruction, the servo driver updates the output speed of the motor; The motor drives the screw to generate a new speed, thereby adjusting the extrusion speed of the corresponding polymer melt.

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