Distributed fiber based extruder shear heat monitoring control method and system

Abstract

The present application relates to cable extrusion temperature control technology field, disclose a kind of extruder shear heat monitoring control method and system based on distributed optical fiber.The method comprises: based on along distribution curve and morphological identification to confirm shear heat core position, and demarcate high-energy potential well interval;Rheological response coordinate system is constructed and demarcated rheological diamond target area;By judging the position relationship between operating state point and target area, generate rheological state determination result;Start reverse pulse decoupling control, calculate decoupling strategy parameters, and execute decoupling strategy, until operating state point stable regression target area after resuming normal control.The present application solves the problem of temperature control failure caused by shear heat drift and "the colder the hotter" positive feedback trap in high-speed extrusion, converts fuzzy rheological state into quantitative geometric criterion, realizes the accurate identification of shear deadlock state and nonlinear emergency decoupling, significantly improves the stability and safety of extrusion production.

Description

Technical Field

[0001] This invention relates to the field of temperature control technology for cable extrusion, and more specifically, to a method and system for monitoring and controlling the shear heat of an extruder based on distributed optical fiber. Background Technology

[0002] With the increasing demands for capacity and quality in high-speed cable production processes, precise control of the internal thermal state of the cable extruder barrel has become crucial for determining wire diameter stability and insulation quality. However, traditional temperature control methods generally face bottlenecks in control accuracy, often exhibiting significant overshoot and oscillations during high-speed ramp-up phases. These methods often rely on a single-dimensional analysis of static temperature deviations or linear adjustments based on fixed heating / cooling logic. They neglect the dynamic drift characteristics of shear heat generation locations during high-speed extrusion and the complex strong coupling effect between cooling action and melt viscosity—a state known as shear lock-up. Specifically, at high shear rates, forceful cooling leads to an exponential increase in melt viscosity, inducing a surge in screw shear friction work. In this case, the "viscosity increment heat generation" introduced by cooling exceeds the "sensible heat removed by cooling," resulting in a nonlinear positive feedback trap of "the colder it gets, the hotter it gets." Therefore, how to shift from discrete temperature point monitoring to continuous gradient sensing across the entire domain, transforming single temperature negative feedback into dynamic decoupling of the rheological state, and thus overcoming the physical limitations of shear lock-up, is a key technical challenge to be solved in this field.

[0003] In the prior art, patent CN219214054U discloses a screw extruder control system. This system includes a barrel, control device, heater, fan, and vacuum device. The barrel is divided into multiple zones, each equipped with an independent heater and fan. The control device enables independent temperature control of each zone, while the vacuum device removes air bubbles from the barrel. By combining segmented independent temperature control with air bubble removal, it improves the performance and quality of extruded plastic products, providing a fundamental technical solution for multi-zone temperature control. Patent CN222039552U discloses an extruder barrel temperature monitoring device. This device consists of a temperature sensor, PLC controller, computer, and heating belt. The temperature sensor collects internal barrel temperature data, which is transmitted to the computer via the PLC controller. A PID control algorithm calculates the temperature deviation and adjusts the heating current accordingly. This combination of sensor and PID algorithm achieves precise control of the extruder barrel temperature, solving the problem of insufficient accuracy in traditional temperature control.

[0004] However, while the two existing technologies mentioned above have some value in segmented temperature control and basic temperature regulation, they fail to address the core pain points of dynamic shear heat drift, strong coupling between viscosity and shear heat, and shear lock-up in high-speed cable extrusion scenarios. Specifically, the patent with authorization announcement number CN219214054U focuses on multi-region independent heating and bubble removal, still relying on discrete temperature control logic and failing to achieve continuous thermal state sensing across the entire barrel, thus unable to accurately locate dynamically drifting shear heat sources. The patent with authorization announcement number CN222039552U focuses on single-temperature negative feedback regulation, only optimizing temperature deviation through a PID algorithm, without addressing the dynamic decoupling of rheological states, and cannot overcome the nonlinear positive feedback trap of "the colder it is, the hotter it gets." Neither of these technologies establishes a coupling processing mechanism between shear heat and melt viscosity, making it impossible to predict the risk of temperature overshoot during high-speed ramp-up and to balance melt flowability and temperature stability during temperature control, failing to meet the refined requirements of high-speed cable production for temperature control accuracy and disturbance resistance. Summary of the Invention

[0005] This invention is applicable to high-speed cable extrusion processes, particularly temperature control systems for extruders equipped with distributed fiber optic temperature measurement. By morphologically identifying the location of dynamically drifting shear heat cores through the distribution curve along the extrusion line, and defining high-potential well regions based on the dynamic domain radius function, it solves the technical problem of traditional fixed-point monitoring failing to capture moving heat sources. A rheological response coordinate system is constructed using the control input change rate and the rheological feedback change rate. Combined with a rheological rhomboid target area, implicit rheological causal relationships are made explicit as the geometric trajectories of operating state points, accurately identifying shear lock-up states caused by strong coupling between cooling actions and melt viscosity. Reverse pulse decoupling control calculates decoupling parameters based on the lock-up depth, executing a decoupling strategy that includes a release period for heating and viscosity reduction operations and a suppression period for rapid heat dissipation operations, breaking the nonlinear positive feedback trap of "the colder it is, the hotter it gets." This invention achieves full-domain visualization and perception of the complex rheological state inside the extruder barrel and precise locking of key risk sources, ensuring a seamless switch from nonlinear emergency intervention to steady-state control, significantly improving wire diameter stability and production safety.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for monitoring and controlling shear heat in extruders based on distributed optical fibers includes:

[0008] The original temperature data distributed along the entire length of the extruder barrel is acquired, and the original temperature data is smoothed and reconstructed to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel. Morphological recognition is performed on the along-path distribution curve to confirm the location of the shear heat core. A dynamic domain radius function is constructed based on the location of the shear heat core. The high potential well interval is delineated according to the dynamic domain radius function. The energy state of the high potential well interval is quantified to generate a thermal energy characteristic report.

[0009] A rheological response coordinate system is constructed based on the thermal energy characteristic report. A rheological rhomboid target area is defined in the rheological response coordinate system. The positional relationship of the rheological rhomboid target area is judged to obtain the rheological state determination result.

[0010] Based on the rheological state determination results, a reverse pulse decoupling control is formulated. The decoupling parameters used to execute the decoupling strategy are calculated, and the decoupling strategy is executed according to the decoupling parameters to complete the control handover.

[0011] Furthermore, the path distribution curve includes:

[0012] A one-dimensional thermal potential energy coordinate system is established by selecting the geometric center section where the feed inlet of the extruder barrel is located as the origin of the coordinate system. The coordinate axes of the thermal potential energy coordinate system are parallel to the central axis of the extruder barrel.

[0013] Using distributed optical fibers, raw temperature data with location tags are collected on the extruder barrel. The raw temperature data is then smoothly reconstructed to generate a path distribution curve with clear physical meaning and differentiability everywhere.

[0014] The smooth reconstruction adopts a piecewise polynomial fitting method based on physical continuity constraints. The mathematical expression of the distribution curve along the process is a piecewise cubic function. The mathematical expression uses the position coordinate variable in the thermal potential energy coordinate system as the independent variable. The constraint condition is that the function value, first derivative and second derivative of the distribution curve along the process are continuous at each original temperature data position. The position coordinate variable represents the absolute physical coordinate of the extruder barrel along the material extrusion direction.

[0015] Furthermore, the confirmed location of the shear heat core includes:

[0016] By taking the first and second derivatives of the distribution curve along the friction with respect to the position coordinate variables, the friction gradient curve and the friction thermal curvature curve are obtained respectively.

[0017] Traverse the gradient curve along the process and search for regions that simultaneously satisfy feature one and feature two. Feature one is that the function value on the gradient curve along the process is greater than the sum of the preset baseline negative gradient line and the preset gradient anomaly threshold. Feature two is that the gradient curve along the process exhibits an asymmetric isolated peak shape that first rises steeply and then falls slowly.

[0018] Once a region that simultaneously satisfies both feature one and feature two is found, the zero-crossing point of the thermal curvature curve along the path is obtained, and the position of the zero-crossing point in the thermal potential energy coordinate system is marked as the candidate thermal core position.

[0019] Obtain the function values ​​of the distribution curve along the path at the candidate heat core position within the current and multiple consecutive data output cycles, and construct a time-temperature sequence; perform linear regression fitting on the time-temperature sequence to obtain the slope of the fitted line, i.e. the temperature rise rate;

[0020] When the temperature rise rate is greater than the preset pure thermal conduction temperature rise threshold, the candidate heat core location is confirmed as the shear heat core location.

[0021] Furthermore, the generated thermal energy characteristic report includes:

[0022] A dynamic domain radius function is constructed by obtaining the location of the shear heat core inside the extruder barrel and the real-time screw speed.

[0023] In the thermal potential energy coordinate system, with the shear heat core position as the center, the upstream and downstream boundaries of the high potential well interval are defined by the dynamic domain radius function, and the average thermal potential energy is obtained by integrating the distribution curve along the path within the high potential well interval.

[0024] The upstream and downstream boundaries, along with the average thermal potential energy and the coordinate values ​​of the shear heat core location in the thermal potential energy coordinate system, are combined to obtain a thermal energy characteristic report.

[0025] Furthermore, the construction of the rheological response coordinate system includes:

[0026] Analyze the thermal energy characteristic report, extract the upstream and downstream boundaries of the high potential well region in the thermal potential energy coordinate system, and obtain the physical actuators corresponding to the high potential well region.

[0027] Based on the physical actuator, a standardized control action signal and rheological feedback signal are defined. The first derivative of the control action signal is obtained to obtain the control input rate of change; the first derivative of the rheological feedback signal is obtained to obtain the rheological feedback rate of change. A two-dimensional Cartesian coordinate system, namely the rheological response coordinate system, is established with the control input rate of change on the horizontal axis and the rheological feedback rate of change on the vertical axis.

[0028] The control input rate of change and the rheological feedback rate of change are projected as an ordered pair onto the rheological response coordinate system to form a dynamically changing geometric point, i.e., the operating state point.

[0029] Furthermore, the rheological rhomboid target region includes:

[0030] Four vertices are marked in the rheological response coordinate system, namely the upper limit point of viscosity fluctuation, the slippage limit point, the thermal response boundary point, and the deadlock critical point. The upper limit point of viscosity fluctuation corresponds to the maximum positive value of the rheological feedback change rate caused by the inherent randomness of the extrusion process when the control input change rate is zero. It is located on the positive half-axis of the Y-axis of the rheological response coordinate system. The slippage limit point corresponds to the minimum negative value of the rheological feedback change rate that can be achieved when the rheological feedback signal drops sharply due to the wall slippage of the melt on the inner wall of the extruder barrel. It is located on the negative half-axis of the Y-axis of the rheological response coordinate system.

[0031] Connecting the upper limit point of viscous fluctuation, the deadlock critical point, the slippage limit point, and the thermal response boundary point in sequence forms an asymmetric closed region, namely the rheological rhomboid target region.

[0032] Furthermore, the obtained rheological state determination result includes:

[0033] Real-time monitoring of the positional relationship between the operating status points and the rheological rhomboid target area;

[0034] If the running state point falls outside the rheological rhomboid target area and is simultaneously located above the line segment connecting the upper limit point of viscous fluctuation and the deadlock critical point in the rheological response coordinate system, i.e. the upper right region of the first quadrant, a rheological state determination result marking the shear deadlock state is generated.

[0035] If the operating state point is located inside the rheological rhombus target region, or outside the rheological rhombus target region but in the second or third quadrant, a rheological state determination result marked as a normal temperature control state is generated.

[0036] Furthermore, the decoupling parameters include:

[0037] Calculate the vertical Euclidean distance from the running state point to the upper right boundary of the rheological rhomboid target area, and define the vertical Euclidean distance as the deadlock depth. The upper right boundary refers to the line segment connecting the upper limit point of viscous fluctuation and the deadlock critical point.

[0038] Based on the deadlock depth, a fixed pulse reference period is set, and two core time parameters constituting the pulse reference period are calculated, namely the release period duration and the inhibition period duration.

[0039] The pulse reference period, release period duration, and inhibition period duration are the decoupling parameters.

[0040] Furthermore, the execution decoupling strategy includes:

[0041] The execution of the decoupling strategy is divided into two operations: heating up to reduce viscosity and rapid heat dissipation.

[0042] The temperature rise and viscosity reduction operation involves setting the cooling output of the hardware unit responsible for heat dissipation in the physical actuator to zero during the release period, while simultaneously sending a command to the main motor responsible for driving the screw rotation to reduce the real-time screw speed. The rapid heat dissipation operation follows immediately after the release period ends. During the suppression period, the cooling output of the hardware unit responsible for heat dissipation in the physical actuator is turned on to its maximum value to form a strong cooling pulse, while simultaneously restoring the real-time screw speed to its value before reduction.

[0043] While implementing the decoupling strategy, a safety counter is set to continuously monitor the position of the operating status point in the rheological response coordinate system. If the operating status point falls into the rheological rhomboid target area at the end of the pulse reference period, the safety counter is incremented by one; otherwise, it is cleared to zero.

[0044] When the count value of the safety counter reaches the preset safety threshold, it is determined that the shear deadlock state has been released, and the reverse pulse decoupling control is terminated.

[0045] A distributed optical fiber-based extruder shear heat monitoring and control system is used to implement the above method. The system includes:

[0046] Thermal energy feature sensing module: used to acquire raw temperature data distributed along the entire length of the extruder barrel, smooth and reconstruct the raw temperature data to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel, perform morphological recognition on the along-path distribution curve to confirm the location of the shear heat core, construct a dynamic domain radius function based on the location of the shear heat core, delineate the high potential well interval according to the dynamic domain radius function, quantify the energy state of the high potential well interval to generate a thermal energy feature report;

[0047] Rheological deadlock identification module: It is used to construct a rheological response coordinate system based on the thermal energy characteristic report, delineate a rheological rhomboid target area in the rheological response coordinate system, perform positional relationship judgment on the rheological rhomboid target area, and obtain the rheological state judgment result;

[0048] Reverse decoupling control module: It is used to formulate reverse pulse decoupling control based on the rheological state determination result, calculate the decoupling parameters used to execute the decoupling strategy, execute the decoupling strategy according to the decoupling parameters, and complete the control switch.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] This invention confirms the location of the shear heat core by performing morphological recognition on the distribution curve along the process and delineates the high potential well interval based on the dynamic domain radius function, solving the problem of fuzzy heat source location caused by the inability of traditional discrete monitoring to capture dynamic shear heat drift. The rheological response coordinate system combined with the rheological rhomboid target area makes the implicit causal relationship between the rate of change of control input and the rate of change of rheological feedback explicit as the geometric trajectory of the operating state point, accurately identifying the shear deadlock state caused by the strong coupling between cooling control action and melt viscosity, solving the problem that traditional control cannot judge rheological anomalies based solely on temperature deviation. The reverse pulse decoupling control calculates decoupling parameters based on the deadlock depth and executes a decoupling strategy that includes a temperature rise and viscosity reduction operation with a release period and a rapid heat dissipation operation with a suppression period, breaking the vicious positive feedback loop of "the colder it is, the hotter it gets" and achieving a seamless switch from nonlinear emergency intervention to steady-state control. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 A flowchart illustrating the method for monitoring and controlling shear heat in an extruder based on distributed optical fiber, as provided in an embodiment of the present invention.

[0053] Figure 2 A schematic diagram of the physical mapping between distributed optical fiber deployment along the barrel of an extruder and the establishment of a thermal potential energy coordinate system, provided in an embodiment of the present invention.

[0054] Figure 3 A schematic diagram illustrating the principle of the distribution curve along the path provided in an embodiment of the present invention;

[0055] Figure 4 This is a schematic diagram illustrating the principle of shear heat core recognition provided in an embodiment of the present invention;

[0056] Figure 5 A schematic diagram of the distribution of the rheological response coordinate system and the rheological rhomboid target region provided in this embodiment of the invention;

[0057] Figure 6 A functional block diagram of a distributed optical fiber-based extruder shear heat monitoring and control system provided in an embodiment of the present invention. Detailed Implementation

[0058] 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.

[0059] Example 1

[0060] Please see Figure 1 As shown, this embodiment provides a method for monitoring and controlling the shear heat of an extruder based on distributed optical fibers, including:

[0061] Step S10: Obtain the original temperature data distributed along the entire length of the extruder barrel, smooth and reconstruct the original temperature data to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel, perform morphological recognition on the along-path distribution curve to confirm the shear heat core position, construct a dynamic domain radius function based on the shear heat core position, delineate the high potential well interval according to the dynamic domain radius function, quantify the energy state of the high potential well interval to generate a thermal energy characteristic report.

[0062] Further, step S10 includes:

[0063] Step S11: Obtain the original temperature data distributed along the entire length of the extruder barrel, and perform smooth reconstruction on the original temperature data to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel.

[0064] In high-speed cable extrusion, the extruder barrel is a tubular container that houses the screw, heats and melts the polymer, and generates high-pressure extrusion. Complex phase transitions and rheological processes occur inside the extruder barrel. During extrusion, distributed optical fibers, acting as global temperature sensing units, are tightly wound and helically fixed to the outer wall of the extruder barrel. The relative positional relationship between the distributed optical fibers and the outer wall of the extruder barrel remains constant throughout the production cycle. The temperature field distribution inside the extruder barrel directly determines the plasticization uniformity of the cable material and the wire diameter stability of the final product. Shear heat, the unexpected heat generated during high-speed screw rotation due to friction between material layers and between the material and the wall, is the main physical source of localized temperature runaway. The location of shear heat generation is highly fluid and uncertain, drifting to any section of the extruder barrel with changes in screw speed and back pressure. Therefore, this invention establishes a reference framework that can accurately map temperature signals acquired by distributed optical fibers to the physical space of the extruder barrel, and outputs a structured quantitative index. The purpose is to transform the traditional segmented monitoring based on thermocouples into an active gradient monitoring that covers the entire length of the extruder barrel and has a continuous spatial coordinate index, so as to provide a unified and absolute spatial reference for the future.

[0065] Specifically, to describe the axial position of the thermodynamic event of shear heat generation on the slender extruder barrel, the geometric center section of the extruder barrel's feed inlet is selected as the origin O, establishing a fixed one-dimensional coordinate system, namely the thermal potential energy coordinate system. The coordinate axes of the thermal potential energy coordinate system are defined as parallel to the central axis of the extruder barrel, denoted by the letter L, with the positive direction pointing towards the die outlet of the extruder barrel. This ensures that the thermal potential energy coordinate system is consistent with the physical path of material flow. See [link to relevant documentation]. Figure 2 This is a schematic diagram illustrating the physical mapping between distributed optical fiber deployment along the barrel of an extruder and the establishment of a thermal potential energy coordinate system, provided by an embodiment of the present invention. For example... Figure 2 As shown, the horizontal tubular structure at the top of the diagram represents the extruder barrel, and the dashed line inside represents the central axis of the screw. Distributed optical fibers are tightly wound in a spiral around the outer wall of the extruder barrel and connected to the DTS host on the left. The straight line with an arrow at the bottom of the diagram represents the established thermal potential energy coordinate system, identified by the letter L. The origin O of the coordinate axes is aligned with the geometric center section of the feed inlet above the extruder barrel. The vertical dashed lines illustrate how physical points on the distributed optical fibers are mapped to position coordinates on the coordinate axes, intuitively demonstrating the transformation from physical space to one-dimensional mathematical space.

[0066] A Direct-Sensing Transmission (DTS) host continuously collects backscattered Raman spectral signals on the outer metal wall surface of an extruder barrel via distributed optical fibers. The DTS host is a measuring device that uses optical fiber as the sensing medium, such as distributed optical fibers, to measure the temperature distribution along the fiber's length. Its working principle is based on the Raman scattering effect and optical time-domain reflectometry. A laser inside the DTS host periodically injects high-power, short-pulse laser light (laser pulses) into the connected distributed optical fibers. When the laser pulses propagate through the fiber core, photons undergo elastic and inelastic collisions with the fiber material molecules, generating backscattered light. The Raman scattered light from the inelastic collisions includes Stokes light and anti-Stokes light. The intensity of the anti-Stokes light is highly sensitive to temperature, while the intensity of the Stokes light is unaffected by temperature. The DTS host demodulates the temperature information at the scattering location by detecting the intensity ratio of the returned anti-Stokes light to the Stokes light. Simultaneously, based on the time difference between the laser pulse emission time and the return time of the scattered light (time of flight), the optical path length from the scattering location to the DTS host is calculated. In this principle, the distributed optical fiber is not only a channel for optical transmission but also a continuously distributed set of temperature-sensing elements. The spatial spacing of the distributed optical fiber sampling points is set based on the physical dimensions and thermal diffusion characteristics of the extruder barrel's heating zone; for example, the spatial spacing is set to 0.5 meters. The aim is to capture minute temperature changes at different axial positions of the extruder barrel. Finally, the DTS host outputs a series of raw temperature data with location tags, for example, using... This represents the instantaneous temperature value demodulated by the DTS host after multiple laser pulse accumulation and averaging at the i-th distributed fiber sampling point. This represents the position coordinates of the i-th distributed optical fiber sampling point in the thermal potential energy coordinate system, where i is the index of the distributed optical fiber sampling point, ranging from 1 to M-1. M is the total number of sampling points of the distributed optical fiber on the extruder barrel, set according to the ratio of the total layout length of the distributed optical fiber on the extruder barrel to the spatial interval of the sampling points. The total layout length refers to the sum of the actual physical path length traversed by the distributed optical fiber from the feed inlet position of the extruder barrel, along the outer wall surface of the extruder barrel, to the die position of the extruder barrel. The purpose is to ensure that the monitoring points cover the entire path from the feed inlet to the die, reflecting the thermal state of the entire production line without omission. The position coordinates of the distributed optical fiber sampling points are obtained by calculating the distance value based on the flight time of the laser pulse emitted by the DTS host in the distributed optical fiber using the principle of optical time-domain reflectometry, and then combining this with geometric projection correction using the helical winding pitch of the distributed optical fiber on the extruder barrel to obtain the axial coordinates.

[0067] Because the physical heat conduction process is inherently continuous, the thermal diffusion effect of the extruder barrel's metal wall prevents abrupt temperature changes; therefore, the actual temperature distribution is a smooth curve. However, the raw temperature data output by the DTS host is a spatially discontinuous set of points and includes high-frequency jitter caused by optical noise from the DTS host's measurement. To eliminate the measurement blind zone between distributed fiber optic sampling points in the thermal potential energy coordinate system and obtain a physically meaningful, everywhere differentiable continuous function, the raw temperature data is processed to generate a distribution curve along the process. The friction-path distribution curve is a mathematical function model describing the continuous change of temperature on the outer wall of the extruder barrel with axial position, and its domain covers the entire physical length from the feed inlet to the die. The aim is to provide a globally smooth analytical expression, filling the measurement gaps between discrete sampling points, enabling continuous numerical analysis and high-order differential calculations of the thermal state of any small region on the extruder barrel. The construction of the continuous function employs a piecewise polynomial fitting method based on physical continuity constraints to smoothly reconstruct the original temperature data. The construction logic uses a set of continuous piecewise cubic functions to shape the true friction-path temperature distribution on the extruder barrel. To conform to the physical laws of heat conduction, the generated friction-path distribution curve maintains continuous temperature values ​​at each original temperature data point. Furthermore, the first derivative representing the continuity of heat flux density and the second derivative representing the continuity of thermal curvature must also remain strictly continuous throughout the entire domain. Based on this logic, the mathematical expression for the friction-path distribution curve is: Where k represents the coordinate variable of any position in the thermal potential energy coordinate system, serving as the independent variable of the distribution curve along the path in the formula, and its effective value range is limited to the current distributed fiber sampling point. With the next distributed fiber sampling point The segmented intervals formed The purpose of this is to describe the temperature distribution within a specific effective range of values. From a macroscopic perspective, the position coordinate variable k represents the absolute physical coordinate of the extruder barrel along the material extrusion direction. Indicates k relative to The relative positions are determined to reduce numerical calculation errors and simplify the process of solving for fitting coefficients; The zero-order thermal fitting coefficient represents the segmented interval corresponding to the i-th distributed fiber sampling point. Numerically, it is represented by the calculated temperature value at the i-th distributed fiber sampling point, ensuring that the distribution curve along the path is anchored to the actual measurement value of the DTS host. It represents the first-order heat flux fitting coefficient of the segmented interval corresponding to the i-th distributed fiber sampling point. It physically reflects the first derivative of the along-path distribution curve at the i-th distributed fiber sampling point, ensuring that the tangent slope of the along-path distribution curve does not change abruptly at the distributed fiber sampling point. It represents the second-order thermal curvature fitting coefficient of the segmented interval corresponding to the i-th distributed fiber sampling point. It physically reflects the second derivative of the distribution curve along the path at the i-th distributed fiber sampling point, ensuring the curvature continuity of the distribution curve along the path. The three coefficients represent the third-order thermal curvature fitting coefficients for the segmented interval corresponding to the i-th distributed fiber sampling point, used to adjust for minor fluctuations in the path distribution curve within the segmented interval. These four fitting coefficients are obtained by solving a global system of simultaneous equations. Specifically, for each internal distributed fiber sampling point in the thermal potential energy coordinate system, according to the physical continuity law of heat conduction, the first derivative of the path distribution curve of the segmented interval corresponding to the (i-1)-th distributed fiber sampling point at the last distributed fiber sampling point is equal to the first derivative of the path distribution curve of the segmented interval corresponding to the i-th distributed fiber sampling point at the first distributed fiber sampling point. Simultaneously, the second derivatives of both are required to be equal. Substituting these derivative continuity conditions into the above mathematical expression, a linear system of equations is constructed regarding all unknown second-order thermal curvature fitting coefficients. The coefficients are obtained by solving this linear system. (See also...) Figure 3 This is a schematic diagram illustrating the principle of the path distribution curve provided in an embodiment of the present invention. For example... Figure 3 As shown, the horizontal axis represents the position coordinate variable k in the thermal potential energy coordinate system, defining the segmented interval formed by the current distributed fiber sampling point and the next distributed fiber sampling point, i.e. The vertical axis represents the instantaneous temperature value demodulated by the DTS host. The two solid blue dots in the graph represent the locations... and Raw temperature data collected at the location and The smooth green curve connecting the two blue dots represents the generated temperature distribution curve along the process, vividly illustrating the physical process. Due to the thermal diffusion effect of the extruder barrel's metal wall, the temperature field exhibits a continuous and smooth variation between the two discrete sampling points, rather than a step jump. The green hollow dots and dashed lines in the figure indicate the relative position terms in the formula. This indicates that the instantaneous temperature value at any point on the curve is obtained by using... The calculation is obtained by substituting the mathematical expression of the distribution curve along the path into the calculation benchmark of the relative position. Figure 3 It intuitively illustrates how mathematical methods can be used to fill the blind spots between discrete measurement points and restore the true thermodynamic state.

[0068] Step S12: Perform morphological recognition based on spatial gradient on the distribution curve along the path to locate the candidate hot core positions where the temperature gradient changes abruptly, and perform temperature rise rate verification on the candidate hot core positions to confirm the shear hot core positions.

[0069] The heat distribution curve along the extruder barrel accurately characterizes the static heat distribution. To further analyze the dynamic heat source characteristics behind the temperature distribution from a thermodynamic perspective, in-depth morphological analysis is performed based on the heat distribution curve. Under high-speed extrusion conditions, the intense friction between the material and the screw and the inner wall of the extruder barrel generates a large amount of shear heat. The center of this endogenous heat generation is the main physical source of localized temperature runaway. The location of shear heat generation is highly fluid, dynamically drifting between the end of the compression section and the beginning of the metering section as the screw speed, back pressure, and melt flow index of the material change. Thanks to the high-order differentiability of the heat distribution curve, it can overcome the hysteresis limitations of traditional temperature threshold alarms, capturing minute gradient abrupt changes in the temperature field. This allows for early warning and precise location of moving shear heat generation locations before significant heat accumulation. Therefore, morphological recognition based on spatial gradients is introduced.

[0070] Specifically, using the friction distribution curve as input, the first derivative of the friction distribution curve with respect to the position coordinate variable k is calculated to obtain the friction gradient curve G(k). The friction gradient curve represents the function curve showing the slope of the tangent line to the friction distribution curve at each position coordinate variable k as a function of position. Its function is to reveal the rate of change of the friction distribution curve along the axial direction of the extruder barrel, and to capture the implied abrupt changes in heat flux density within the friction distribution curve; the mathematical expression is: Where, the symbol d represents the differential operator, i.e. This represents the change in the function value of the distribution curve along the path under a small spatial increment. This represents a small increment in the position coordinate variable k. Physically, the rate of change of heat flux density along the axial direction of the extruder barrel is characterized, i.e., the temperature change caused by each unit distance traveled. The second derivative of the friction distribution curve with respect to the position coordinate variable k is used to obtain the friction thermal curvature curve H(k). This friction thermal curvature curve represents the function curve of the rate of change of the friction gradient curve with position; its function is to characterize the concavity and convexity of the friction distribution curve and to pinpoint the extreme points of the friction gradient curve G(k). The mathematical expression is: After obtaining the friction gradient curve G(k) and the friction thermal curvature curve H(k), a baseline negative gradient line is set. The reference negative gradient line represents the theoretical gradient benchmark formed by the extruder barrel under static, shear-free conditions, relying solely on external heaters to maintain the temperature difference and dissipating heat through natural convection. This benchmark is obtained through statistical analysis of historical data collected during the extruder's shutdown and heat preservation state. Simultaneously, a gradient anomaly threshold is set. The gradient anomaly threshold is set based on the measurement noise level of the DTS host. For example, the gradient anomaly threshold is set to 3 times the noise standard deviation to filter out random fluctuation interference.

[0071] The specific process of morphological recognition is as follows: Traverse and scan the gradient curve along the gradient path, searching for regions that simultaneously satisfy the following two geometric features: Feature one is that the function value on the gradient curve along the path is greater than the sum of the baseline negative gradient line and the gradient anomaly threshold, i.e. The second characteristic is that the gradient curve along the path exhibits an asymmetric isolated peak shape, characterized by a "steep rise followed by a slow decline." This asymmetric isolated peak shape is a typical spatial fingerprint of the location where shear heat is generated. Since the location of shear heat generation is a point heat source, the heat diffuses outwards, forming a Gaussian temperature distribution with a high center and low sides. The corresponding first derivative, i.e., the gradient curve along the path, is represented by peak-valley pairs, while the second derivative, i.e., the zero point of the thermal curvature curve along the path, corresponds to the center of the heat source. After searching for regions that simultaneously satisfy the above two geometric characteristics, the zero-crossing point of the thermal curvature curve along the path is further located. The zero-crossing point is the point where the function value of the thermal curvature curve along the path changes from a positive value to a negative value or from a negative value to a positive value. The position of the zero-crossing point in the thermal potential energy coordinate system is marked as the candidate heat core location. To further distinguish whether the temperature rise is caused by shear friction or by an external heater malfunction, the current heat transfer curve generated by the DTS host and historical heat transfer curves generated in multiple consecutive DTS host data output cycles are extracted. The data output cycle is based on the heat conduction time constant of the extruder barrel's metal wall to ensure the capture of the true temperature trend rather than instantaneous noise. For example, the data output cycle is set to 2. The function values ​​of the heat transfer curves generated in the current and multiple consecutive past data output cycles at the candidate heat core locations are extracted to construct a time-temperature sequence. The time-temperature sequence is then subjected to linear regression using the least squares method to obtain the slope of the fitted line, which is determined as the temperature rise rate at the candidate heat core location. A pure thermal conductivity temperature rise threshold V is set, representing the physical limit of the maximum temperature rise rate achievable by external heating. To eliminate interference from heat loss in actual operating conditions, the calculation combines heating efficiency and barrel wall thermal resistance. Specifically, the formula for calculating the pure thermal conductivity temperature rise threshold is: ,in, The maximum power density of the external heater is obtained by reading the manufacturer's nameplate of the external heater of the extruder; The heating efficiency is the ratio of electrical energy to barrel heat energy, which can be obtained by consulting the extruder's factory parameter manual. This indicates the temperature difference between the barrel surface and the environment. It is obtained by subtracting the ambient temperature from the real-time barrel surface temperature collected by the DTS main unit. The thermal resistance of the extruder barrel wall can be obtained by referring to the manufacturer's parameter manual for the extruder barrel and insulation layer, or by having the corresponding thermal resistance coefficient provided directly by the equipment manufacturer. Specific heat capacity is indicated by , which can be obtained from the standard mechanical engineering materials handbook based on the barrel material; 'm' represents the equivalent mass of the barrel, which can be calculated from corresponding drawings or obtained from the equipment manual. Only when the temperature rise rate exceeds the pure thermal conduction temperature rise threshold is the temperature rise anomaly at the candidate heat core location determined to be not solely caused by the external heater, but also includes the superimposed effect caused by the shear heat generation location, thus confirming the candidate heat core location as a shear heat core location. See also Figure 4 This is a schematic diagram illustrating the shear heat core recognition principle provided in an embodiment of the present invention. Figure 4 As shown, the graph is divided into three parts: upper, middle, and lower, all sharing the same horizontal axis, which represents the position coordinate variable k in the thermal potential energy coordinate system. The top curve shows the friction distribution curve generated in step S11, with a clear local temperature rise in the middle, corresponding to the heat accumulation caused by the shear heat generation location. The middle curve shows the friction gradient curve G(k) obtained by taking the first derivative of the friction distribution curve, as shown in Figure 4. In the region corresponding to the temperature rise, the function value exceeds the threshold line shown by the dashed line. ,Right now It exhibits an asymmetric, isolated peak shape characterized by a "steep rise followed by a slow decline." The bottom graph shows the thermal curvature curve H(k) obtained by taking the second derivative of the distribution curve along the path. The solid red dots in the graph indicate the zero-crossing point where H(k) changes from a positive value across the zero axis to a negative value. The vertical black dashed line in the graph runs through the three graphs, visually demonstrating that this zero-crossing point precisely corresponds to the geometric center of the temperature rise bulge above. The vertical position of this dashed line on the horizontal axis is marked as the candidate hot core location.

[0072] Step S13: Construct a dynamic domain radius function based on the location of the shear heat core, delineate the high potential well interval according to the dynamic domain radius function, and quantify the energy state of the high potential well interval to generate a thermal energy characteristic report.

[0073] The shear heat core location enables precise locking of the center of the moving heat source. To achieve comprehensive control over the temperature field inside the extruder barrel, a dynamic spatial control boundary is further constructed based on the shear heat core location. Since the melt flows continuously within the extruder barrel, and the barrel has excellent thermal conductivity, the heat generated at the shear heat core location not only concentrates at that single point but also diffuses upstream and downstream along with melt flow and heat conduction, forming a heat diffusion area with a certain spatial span. To ensure effective coverage of the heat diffusion area, preventing overheated melt from backfilling with heat, and to avoid excessive intervention in the normal plasticizing zone, preventing unnecessary cooling that could increase material viscosity and screw torque, this invention constructs a dynamic control boundary based on the shear heat core location, tightly coupled with process parameters.

[0074] Specifically, to accurately define the physical boundary of heat diffusion, this invention constructs a dynamic domain radius function R(N). The construction logic is based on the Peckley number principle in fluid mechanics, which states that during extrusion, heat transport is determined by both static heat conduction and dynamic heat convection. The static heat conduction range depends on the thermal properties of the material itself and is relatively fixed; while the dynamic heat convection range is positively correlated with the axial velocity of the melt, i.e., linearly related to the real-time screw speed N. To ensure that the control boundary can adaptively expand and contract with production speed, preventing heat from escaping the control zone at high speeds or the control zone from becoming too large at low speeds, a dynamic domain radius function containing a static baseline term and a dynamic correction term is constructed. Based on this construction logic, the mathematical expression of the dynamic domain radius function is: .in, The static heat conduction reference radius, also known as the static reference term, characterizes the inherent range of heat influence solely through conduction when the screw is stationary or at extremely low speeds. It is determined by the physical geometry of the extruder barrel. For example, the static heat conduction reference radius is typically 1.5 to 2 times the inner diameter of the extruder barrel, i.e., the screw diameter. The physical rationale for this setting is that, without strong convection, the effective heat conduction distance in the polymer melt is usually limited by the flow channel cross-sectional dimensions. Beyond this range, heat dissipates significantly due to radial dissipation. Therefore, 1.5 to 2 times the screw diameter is used as the inherent physical boundary of the static heat influence. The thermal convection diffusion coefficient, also known as the dynamic correction term, is obtained through offline experimental calibration: the axial propagation attenuation distance of the temperature wave is measured under a standard screw speed gradient, and the slope of this change with screw speed is calculated. The thermal convection diffusion coefficient reflects the additional axial transport distance of heat for each unit increase in screw speed. N is the real-time screw speed, which, as the independent variable of the function, is directly related to the axial transport speed of the melt.

[0075] In the thermal potential energy coordinate system, with the shear core location as the center, the direction decreasing towards the position coordinate variable k is defined as upstream, and the direction increasing towards the position coordinate variable k is defined as downstream. Extending the radius by a length of R(N) upstream and downstream respectively, we obtain the interval. The high-potential-well region, where C represents the coordinates of the shear heat nucleus in the thermal potential energy coordinate system, is defined as follows: Since the high-potential-well region covers the complete physical path of shear heat generation and diffusion, within this path, the melt not only continuously receives mechanical energy converted into heat from the shear heat nucleus but also experiences local enthalpy peaks due to the limited thermal diffusion rate, resulting in extreme viscosity sensitivity to temperature changes. Therefore, the high-potential-well region physically corresponds to the most intense shearing, the most significant heat accumulation, and the most sensitive viscosity-temperature coupling danger zone. Finally, a thermal energy characteristic report is generated containing the following data items: Data item one is the coordinates of the shear heat nucleus in the thermal potential energy coordinate system; Data item two is the boundary coordinates of the high-potential-well region in the thermal potential energy coordinate system, i.e., the upstream boundary. and downstream boundary The third data item is the average thermal potential energy within the high-potential-well interval. This average thermal potential energy is obtained by performing a definite integral on the distribution curve along the path within the high-potential-well interval and dividing by the interval length. The thermal energy characteristic report not only provides the spatial coordinates of the shear heat generation location but also quantifies the total energy state of thermal accumulation in this region, providing data support for subsequent analysis.

[0076] Step S10 solves the problems of temperature field monitoring blind spots and heat source ambiguity caused by the discreteness of distributed sensor data and the dynamic drift of shear heat sources in high-speed extrusion processes by using the distribution curve along the process, the location of shear heat cores, and thermal energy characteristic reports. In particular, it solves the technical problem that traditional control based solely on absolute temperature thresholds cannot identify early heat flux density anomalies or accurately define heat diffusion boundaries. It achieves full-domain visualization and perception of the complex rheological and thermodynamic coupling state inside the extruder barrel and precise quantitative locking of key risk sources. Among them, the distribution curve along the process reconstructs the discrete original temperature data into a continuous mathematical model that is differentiable everywhere, filling the measurement gap between sampling points and endowing the temperature field with high-order differential characteristics; the shear heat core location uses the morphological recognition of spatial gradient and the physical verification of the time-domain temperature rise rate to overcome the lag of the traditional alarm mechanism and accurately capture the moving shear heat generation center in the early stage of heat accumulation; the thermal energy characteristic report establishes a dynamic physical mapping between the control boundary and the real-time screw speed based on the high potential well interval defined by the dynamic domain radius function, which not only quantifies the local enthalpy peak, but also provides a precise spatial target that takes into account both heat conduction and heat convection characteristics for subsequent rheological decoupling control.

[0077] Step S20: Construct a rheological response coordinate system based on the thermal energy characteristic report, delineate a rheological rhomboid target area in the rheological response coordinate system, perform positional relationship judgment on the rheological rhomboid target area, and obtain the rheological state judgment result.

[0078] Further, step S20 includes:

[0079] Step S21: Construct a rheological response coordinate system based on the thermal energy characteristic report.

[0080] After defining the high-potential-well region and generating a thermal characteristic report, a multi-dimensional rheological state analysis space was constructed based on the data provided by the thermal characteristic report to further analyze the real-time rheological response characteristics of the extruder barrel within this region from the perspective of dynamic control. Given that simple spatial location and static thermal energy data are insufficient to fully characterize the complex dynamic coupling mechanism between "control actions" and "rheological feedback," a rheological response coordinate system based on phase plane analysis was introduced, aiming to make implicit physical causal relationships explicit as geometric coordinate trajectories.

[0081] Specifically, the thermal energy characteristic report is analyzed to extract the boundary coordinates of the high-potential well region in the thermal potential energy coordinate system, i.e., the upstream boundary. and downstream boundary The physical actuator corresponding to the high potential well region is locked. The physical actuator refers to a set of hardware units. The control output of the hardware units directly acts on the physical section of the extruder barrel corresponding to the high potential well region, and changes the thermodynamic and rheological state of the material in the physical section of the extruder barrel. For example, the frequency converter of the fan or the water valve positioner responsible for heat dissipation in the high potential well region, or the main motor responsible for driving the screw rotation.

[0082] To quantify the intensity and direction of the intended cooling intervention applied to the high potential well region, a unified signal representing the cooling adjustment force is needed, corresponding to the control action. For example, a hardware unit within the physical actuator used to adjust heat dissipation in the high potential well region, such as a fan inverter or a water valve positioner, can be selected. Specifically, a standardized control action signal needs to be defined. The physical actuator corresponding to the high potential well interval of the control action signal in time The normalized value of the output signal; where time This represents an instant in discrete time; by taking the first derivative of the control action signal with respect to time, we obtain the rate of change of the control input. ,Right now The rate of change of the control input is a scalar value. When When the value is positive, it indicates that the cooling effect on the high potential well region is being increased; when... A negative value indicates that the cooling effect is being reduced; when When the value is zero, it indicates that the cooling force remains constant. To quantify the dynamic change trend of melt viscosity, the control input rate of change is used as rheological feedback to the control action. This is implemented by a hardware unit in the physical actuator responsible for sensing changes in the rheological state of the material within the high-potential trap region. For example, the main motor responsible for driving the screw rotation. According to rheological principles, under the premise of constant screw speed, the load torque of the main motor is proportional to the melt viscosity in the barrel. A rheological feedback signal is defined. The rheological feedback signal is a real-time torque signal that is acquired at high frequency from the driver corresponding to the main motor and can directly reflect the screw load. The rheological feedback rate of change is obtained by taking the first derivative of the rheological feedback signal with respect to time. ,Right now The rheological feedback rate of change is also a scalar value. When the value is positive, it indicates that the melt viscosity is increasing within the high potential well region; when... A negative value indicates that the melt viscosity is decreasing; when When the value is zero, it indicates that the melt viscosity is in a stable state.

[0083] A two-dimensional Cartesian coordinate system, the rheological response coordinate system, is established with the rate of change of control input on the horizontal axis (X-axis) and the rate of change of rheological feedback on the vertical axis (Y-axis). The construction logic of the rheological response coordinate system is to map the "applied control cause" and the "generated rheological result" onto the same orthogonal plane, thereby transforming the dynamic coupling process in the time domain into a geometric trajectory in the spatial domain. This is achieved by real-time acquisition of the rate of change of control input and the rate of change of rheological feedback, treating them as an ordered pair. Projected onto the rheological response coordinate system, this forms a dynamically changing geometric point, i.e., the operating state point. The position of this operating state point reveals the rheological behavior characteristics of the extruder barrel within the high potential well region. For example, when the operating state point S is located in the first quadrant of the rheological response coordinate system and far from the origin, i.e. and This indicates that the physical actuator has applied a positive control action, which has triggered a significant upward trend in the rheological feedback signal characterizing the melt viscosity resistance. Compared with simply monitoring the absolute value of temperature or torque, this eliminates the influence of the baseline value drift of the basic process parameters and can keenly capture the instantaneous turning point of the extruder barrel dynamic characteristics.

[0084] Step S22: Delineate a rheological rhomboid target region in the rheological response coordinate system.

[0085] After constructing the rheological response coordinate system, in order to accurately identify whether the current rheological state of the extruder barrel has deviated from the safe range, a quantitative geometric boundary is established that can distinguish between the "safe domain dominated by heat conduction" and the "deadlock domain dominated by shear rheology". A closed decision region, namely the rheological rhomboid target region, is constructed in the rheological response coordinate system.

[0086] Specifically, four vertices with clear physical meaning are marked in the rheological response coordinate system: the upper limit point of viscous fluctuation, the slippage limit point, the thermal response boundary point, and the deadlock critical point. The upper limit point of viscous fluctuation corresponds to the maximum positive value of the rheological feedback rate of change caused by the inherent randomness of the extrusion process when the rate of change of the control input is zero. It lies on the positive half-axis of the Y-axis of the rheological response coordinate system, i.e. The basis for setting the upper limit of viscosity fluctuation is that even if the physical actuator does not apply any new cooling adjustment control action, the melt in the extruder barrel will produce natural viscosity fluctuations due to the uneven distribution of the molecular weight of the raw materials. The upper limit for background noise statistics caused by non-controllable factors is set to prevent normal process fluctuations from being misjudged as rheological anomalies caused by cooling actions. For example, it is set to 1.5% of the rated torque value of the main motor. The slippage limit point corresponds to the minimum negative value of the rheological feedback rate of change that can be achieved when the rheological feedback signal drops sharply due to wall slippage of the melt on the inner wall of the extruder barrel. It is located on the negative half-axis of the Y-axis in the rheological response coordinate system, i.e. The design is based on the fact that when wall slippage occurs, the load torque of the main motor driving the screw rotation drops sharply. The slippage limit point, as the lower boundary of the rheological state, is used to define non-viscous deadlock-type rheological anomalies and is set to be symmetrical about the origin with respect to the upper limit point of viscous fluctuations. The thermal response boundary point corresponds to the minimum negative value of the rate of change of control input that can be generated when the physical actuator performs the maximum amplitude cooling reduction control action. It is located on the negative half-axis of the X-axis of the rheological response coordinate system, i.e. The setting is based on the mechanical response limits of the fan frequency converter or water valve positioner in the physical actuator. Among these, This represents the absolute value of the maximum cooling attenuation rate achievable by the hardware unit in the physical actuator used to regulate heat dissipation in the high-potential-well region. It is determined by the physical response limit of the hardware unit. For example, if an electrically controlled regulating water valve changes from fully open to fully closed, that is, corresponding to... If the shortest travel time to U(τ)=0 is 5 seconds, then the minimum negative value of the rate of change of the control input is: Therefore, the maximum negative rate of change amplitude is set to 0.2 per second, and the coordinates of the thermal response boundary point are (-0.2, 0). The deadlock critical point corresponds to a coordinate combination. ,in, This represents the maximum allowed positive rate of change of control input. Representative by The rate of change of rheological feedback corresponding to the increase in melt viscosity. Located in the first quadrant of the rheological response coordinate system. The setting is based on the maximum instantaneous cooling rate that the physical actuator can apply, determined by the thermal stress limit of the extruder barrel material. Specifically, The calculation formula is: ,in, , , and These represent the material's yield strength, Poisson's ratio, coefficient of thermal expansion, and modulus of elasticity, respectively. They are all obtained by consulting conventional reference books such as the "Mechanical Design Handbook" based on the known material specifications of the extruder barrel. The barrel wall thickness is indicated by consulting the extruder's structural drawings. The maximum permissible temperature gradient is indicated by f, which can be directly read from the safety operation manual provided by the equipment manufacturer. f represents the thermal conductivity of the barrel material, used to characterize the thermal resistance effect of cooling conduction into the barrel. The thermal conductivity is set according to the specific material and model of the extruder barrel, and can be obtained by consulting the *Mechanical Design Manual* or the *Handbook of Physical Properties of Metallic Materials* to find its thermal conductivity constant at the standard operating temperature of the extrusion process; or directly from the factory technical parameter specification table provided by the barrel equipment manufacturer. The setting is based on theoretical values ​​calculated using the viscosity-temperature equation of the material, characterizing the temperature at which the material's viscosity-temperature is measured. Under strong cooling, the rate of torque increase caused by the viscosity rise of the melt due to temperature reduction. To accommodate the characteristics of different polymers, this system uses a simplified variant of the standard Arrhenius equation to calculate the torque caused by... The resulting transient viscosity increment The transient viscosity increment represents the difference in material viscosity before and after the application of the strong cooling pulse, and its calculation formula is as follows: ,in, This represents an exponential function with base e. The expected absolute temperature after applying maximum cooling, representing the temperature at which maximum instantaneous cooling efficiency is applied. The expected low point of melt temperature drop is then determined. This can be obtained by directly consulting the lower limit of the extrusion temperature in the material process manual, or by pre-setting the temperature drop value based on the rated cooling capacity of the equipment. This indicates the rated operating temperature, which is determined based on the melting temperature of the cable material to be processed, combined with the optimal processing temperature range recommended in the technical specifications provided by the material supplier. , These represent the pre-exponential viscosity factor and the activation energy coefficient, respectively, both obtained from the Technical Specifications (TDS) provided by the material supplier based on the material type. After obtaining the transient viscosity increment, the transient viscosity increment is multiplied by the torque conversion constant of the main motor to obtain the theoretical extreme value. The torque conversion constant of the main motor is obtained from the manufacturer's manual for the mechanical transmission between the main motor and the screw. Connecting the upper limit point of viscosity fluctuation, the deadlock critical point, the slippage limit point, and the thermal response boundary point sequentially forms an asymmetric closed region, namely the rheological rhomboid target region.

[0087] Step S23: Perform positional relationship judgment on the rheological rhomboid target area to obtain the rheological state judgment result.

[0088] Real-time monitoring of the positional relationship between the operating status point and the rheological rhombus target area; judgment of the positional relationship; if the operating status point falls outside the rheological rhombus target area and is simultaneously located in the upper right region of the first quadrant of the rheological response coordinate system, i.e. When the operating state point is located above the line segment connecting the upper limit of viscosity fluctuation and the deadlock threshold, it indicates that the melt viscosity has increased sharply due to cooling, and the heat increment generated by the screw shearing work has exceeded the heat removed by cooling. In this case, a rheological state determination result marking the shear deadlock state is generated. If the operating state point is located inside the rheological rhombus target region, or outside the rheological rhombus target region but in the second or third quadrant, a rheological state determination result marking the normal temperature control state is generated. See [link to relevant documentation] Figure 5 This is a schematic diagram illustrating the distribution of the rheological response coordinate system and the rheological rhomboid target region provided in an embodiment of the present invention. As shown in the figure, a planar rectangular coordinate system, namely the rheological response coordinate system, is constructed. The horizontal axis represents the rate of change of the control input. The vertical axis represents the rate of change of rheological feedback. I. The asymmetric quadrilateral region enclosed by the green dashed line in the figure is the rheological rhomboid target region. , , and These represent the upper limit point of viscous fluctuation, the deadlock critical point, the slippage limit point, and the thermal response boundary point, respectively. The solid orange dot S in the figure represents the operating state point, located in the upper right region of the first quadrant, and clearly falling outside the rheological rhomboid target area. This indicates a shear deadlock state.

[0089] Step S20, through the rheological response coordinate system, the rheological rhomboid target area, and the rheological state determination results, solves the problem of ambiguous control decision boundaries caused by the strong coupling between control actions and melt viscosity in high-speed extrusion processes. In particular, it addresses the issue that traditional PID control cannot identify the "the colder it is, the hotter it gets" positive feedback trap based solely on temperature deviation, achieving real-time, quantitative discrimination of shear lock-up states. Specifically, the rheological response coordinate system transforms implicit rheological causal relationships into explicit coordinate trajectories; the rheological rhomboid target area defines the geometric boundaries in the coordinate system that distinguish between normal heat conduction and abnormal rheological responses; and the rheological state determination results, based on the real-time positional relationship between the operating state point and the target area, provide clear instructions for subsequently initiating either conventional control or emergency decoupling control.

[0090] Step S30: Based on the rheological state determination result, formulate reverse pulse decoupling control, calculate the decoupling parameters used by the reverse pulse decoupling control to execute the decoupling strategy, execute the decoupling strategy according to the decoupling parameters, and complete the control switch.

[0091] Further, step S30 includes:

[0092] Step S31: Formulate reverse pulse decoupling control based on the rheological state determination result, and calculate the decoupling parameters used by the reverse pulse decoupling control to execute the decoupling strategy.

[0093] When the operating state enters the shear lockout state, it indicates that a vicious positive feedback loop has formed between the cooling control action applied by the physical actuator (i.e., the positive control input rate of change) and the melt viscosity response (i.e., the positive rheological feedback rate of change) within the high potential well region. Specifically, the cooling control action causes a drop in the melt temperature in contact with the extruder barrel wall within the high potential well region, leading to a sharp increase in melt viscosity. This increased viscosity increases the shear friction work generated by the screw rotation on the melt, and the heat generated by this shear friction work exceeds the heat removed by cooling. This creates a shear lockout state where "cooling, increased viscosity, and increased shear heat generation ultimately lead to an even higher temperature." Under this shear lockout state, any conventional negative feedback control strategy based on temperature deviation will fail. For example, a PID controller might continuously issue commands to enhance cooling based on the rising temperature, but this is an erroneous operation that exacerbates the shear lockout state, ultimately leading to screw torque overload or material coking and degradation due to localized overheating. In order to safely resolve this physical contradiction without interrupting production, a counterintuitive emergency control strategy was initiated: reverse pulse decoupling control.

[0094] The rheological state determination result being a shear deadlock state is the activation condition for the reverse pulse decoupling control, which includes a circuit breaker operation and a decoupling strategy. Specifically, when the rheological state determination result is a shear deadlock state, the reverse pulse decoupling control executes a circuit breaker operation, freezing and cutting off the PID temperature control loop acting on the high potential well region, temporarily depriving it of control over the corresponding physical actuator. The purpose is to cut off the source of instructions that exacerbates the shear deadlock state from the control logic level. The PID temperature control loop is a negative feedback control system based on discrete temperature measurement points, such as thermocouples, and the PID (proportional-integral-derivative) algorithm. Its function is to adjust the heating or cooling power of the physical actuator according to the deviation between the target temperature value and the measured value.

[0095] After the melting operation is completed, to quantify the severity of the shear deadlock, decoupling parameters for the decoupling strategy are calculated. Specifically, the vertical Euclidean distance from the operating state point to the upper right boundary of the rheological rhombic target region is calculated, and this vertical Euclidean distance is defined as the deadlock depth. The upper right boundary refers to the line segment connecting the upper limit of viscous fluctuation and the deadlock critical point. The deadlock depth physically represents the degree to which the operating state point deviates from the rheological rhombic target region. The larger the deadlock depth, the more severe the abnormal increase in melt viscosity due to cooling, resulting in a more severe "shear deadlock." Based on the deadlock depth, a fixed pulse reference period E is set according to the thermal relaxation time constant of the melt. The thermal relaxation time constant is a physical quantity that specifically characterizes the time scale required for the melt in the high potential well region and the metal wall of the extruder barrel to reach a new thermal equilibrium after the physical actuator applies or removes the cooling action. For example, the pulse reference period is set to 2. After determining the pulse reference period, the two core time parameters constituting the pulse reference period are calculated, namely the release period duration E1 and the inhibition period duration E2. The release period duration is the time period during which the decoupling strategy performs the temperature-increasing and viscosity-reducing operation. The formula for calculating the release period duration is as follows: Here, min(·) is the minimum value function, which outputs the smallest value in the parentheses, and E3 refers to the deadlock depth. The deadlock depth sensitivity coefficient is set based on the activation energy parameter in the material calibration viscosity-temperature equation. For example, for a common low-smoke halogen-free polyolefin material, the deadlock depth sensitivity coefficient is set to 0.5. The calculation formula is based on the logic that the release period duration is proportional to the deadlock depth; that is, the more severe the shear deadlock state, the longer the time required to perform the temperature-raising and viscosity-reducing operation, but the maximum time shall not exceed one complete pulse reference cycle. The inhibition period duration is the time period during which the decoupling strategy performs rapid heat dissipation. The formula for calculating the inhibition period duration is as follows: The pulse reference period, release period duration, and suppression period duration are the decoupling parameters of the decoupling strategy.

[0096] Step S32: Execute the decoupling strategy according to the decoupling parameters to complete the control handover.

[0097] The decoupling strategy is executed in two parts: a temperature-increase and viscosity-reduction operation, and a rapid heat dissipation operation. The temperature-increase and viscosity-reduction operation involves setting the cooling output of the hardware unit responsible for heat dissipation in the physical actuator to zero (i.e., stopping cooling) during the release period. Simultaneously, a command is sent to the main motor driving the screw to reduce the real-time screw speed, for example, by 1.5% from the original speed. The aim is to rapidly reduce the melt viscosity using a localized temperature rise and weaken the generation of shear heat at its source by reducing the shear rate. The rapid heat dissipation operation follows immediately after the release period. During the suppression period, the cooling output of the hardware unit responsible for heat dissipation in the physical actuator is activated to its maximum value, forming a strong cooling pulse. Simultaneously, the real-time screw speed is restored to its pre-reduction value. The aim is to quickly remove some of the accumulated sensible heat from the extruder barrel wall before the melt viscosity has time to rebound. The decoupling strategy operates on a pulse reference cycle, strictly following the sequence of first executing the temperature-increase and viscosity-reduction operation, followed by the rapid heat dissipation operation.

[0098] While implementing the decoupling strategy, the position of the operating state point in the rheological response coordinate system is continuously monitored, and a safety counter is set to determine whether the shear deadlock has been resolved. At the end of each pulse reference cycle, it is determined whether the operating state point falls inside the rheological rhomboid target area. If it does, the safety counter is incremented; if it overflows again, meaning the operating state point is still outside the rheological rhomboid target area, the safety counter is reset to zero. When the count value of the safety counter reaches the preset safety threshold, the shear deadlock is determined to have been successfully resolved. At this point, the reverse pulse decoupling control is immediately terminated, control is switched back to the PID temperature control loop, normal production is restored, and the stability and continuity of the extrusion process are ensured. The safety threshold is set to ensure that the return of the operating state point is not an instantaneous fluctuation but a stable trend; for example, the safety threshold is set to 3.

[0099] Step S30, through inverse pulse decoupling control, decoupling parameters, and a decoupling strategy, solves the technical challenge of conventional control failure and inability to safely exit under shear deadlock conditions. In particular, it addresses the problem of overcoming the physical contradiction of "the colder it is, the hotter it gets" without interrupting production, achieving a seamless switch from nonlinear emergency intervention to steady-state control in the extrusion process. Specifically, inverse pulse decoupling control, as the overall emergency strategy, provides a complete framework from shear deadlock state assessment to parameterized execution; decoupling parameters quantify complex physical states into executable time commands; and the decoupling strategy ensures the transient effectiveness of the control strategy and its eventual steady-state regression.

[0100] Example 2

[0101] This embodiment, based on Embodiment 1, provides a distributed optical fiber-based extruder shear heat monitoring and control system, such as... Figure 6 As shown, it includes:

[0102] Thermal energy feature sensing module: used to acquire raw temperature data distributed along the entire length of the extruder barrel, smooth and reconstruct the raw temperature data to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel, perform morphological recognition on the along-path distribution curve to confirm the location of the shear heat core, construct a dynamic domain radius function based on the location of the shear heat core, delineate the high potential well interval according to the dynamic domain radius function, quantify the energy state of the high potential well interval to generate a thermal energy feature report;

[0103] Rheological deadlock identification module: It is used to construct a rheological response coordinate system based on the thermal energy characteristic report, delineate a rheological rhomboid target area in the rheological response coordinate system, perform positional relationship judgment on the rheological rhomboid target area, and obtain the rheological state judgment result;

[0104] Reverse decoupling control module: It is used to formulate reverse pulse decoupling control based on the rheological state determination result, calculate the decoupling parameters used to execute the decoupling strategy, execute the decoupling strategy according to the decoupling parameters, and complete the control switch.

[0105] In the thermal energy characteristic sensing module, the process involves acquiring raw temperature data distributed along the entire length of the extruder barrel, smoothing and reconstructing the raw temperature data to obtain a flow distribution curve characterizing the thermal state of the extruder barrel, performing morphological recognition on the flow distribution curve to confirm the location of the shear heat core, constructing a dynamic domain radius function based on the shear heat core location, defining a high potential well interval based on the dynamic domain radius function, quantifying the energy state of the high potential well interval, and generating a thermal energy characteristic report, including:

[0106] Step S11: Obtain the original temperature data distributed along the entire length of the extruder barrel, and perform smooth reconstruction on the original temperature data to obtain the along-the-path distribution curve characterizing the thermal state of the extruder barrel.

[0107] Step S12: Perform morphological recognition based on spatial gradient on the distribution curve along the process to locate the candidate hot core positions where the temperature gradient changes abruptly, and perform temperature rise rate verification on the candidate hot core positions to confirm the shear hot core positions.

[0108] Step S13: Construct a dynamic domain radius function based on the location of the shear heat core, delineate the high potential well interval according to the dynamic domain radius function, and quantify the energy state of the high potential well interval to generate a thermal energy characteristic report.

[0109] In the rheological deadlock identification module, the process of constructing a rheological response coordinate system based on thermal energy characteristic reports, defining a rheological rhomboid target region within the rheological response coordinate system, performing positional relationship judgment on the rheological rhomboid target region, and obtaining the rheological state determination result includes:

[0110] Step S21: Construct a rheological response coordinate system based on the thermal energy characteristic report;

[0111] Step S22: Delineate a rheological rhomboid target region in the rheological response coordinate system;

[0112] Step S23: Perform positional relationship judgment on the rheological rhomboid target area to obtain the rheological state judgment result.

[0113] In the reverse decoupling control module, the step of formulating reverse pulse decoupling control based on the rheological state determination result, calculating the decoupling parameters used by the reverse pulse decoupling control to execute the decoupling strategy, executing the decoupling strategy according to the decoupling parameters, and completing the control handover includes:

[0114] Step S31: Formulate reverse pulse decoupling control based on the rheological state determination result, and calculate the decoupling parameters used by the reverse pulse decoupling control to execute the decoupling strategy;

[0115] Step S32: The decoupling strategy is executed according to the decoupling parameters to ensure the smooth switching of steady-state control.

[0116] The methods and systems of this application may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the method is for illustrative purposes only, and the steps of the method of this application are not limited to the order specifically described above, unless otherwise specifically stated.

[0117] In addition, the parts of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of the corresponding technical solutions in the prior art have not been described in detail, so as to avoid excessive elaboration.

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring and controlling shear heat in an extruder based on distributed optical fiber, characterized in that, The method includes: The original temperature data distributed along the entire length of the extruder barrel is acquired, and the original temperature data is smoothed and reconstructed to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel. Morphological recognition is performed on the along-path distribution curve to confirm the location of the shear heat core. A dynamic domain radius function is constructed based on the location of the shear heat core. The high potential well interval is delineated according to the dynamic domain radius function. The energy state of the high potential well interval is quantified to generate a thermal energy characteristic report. A rheological response coordinate system is constructed based on the thermal energy characteristic report. A rheological rhomboid target area is defined in the rheological response coordinate system. The positional relationship of the rheological rhomboid target area is judged to obtain the rheological state determination result. Based on the rheological state determination results, a reverse pulse decoupling control is formulated. The decoupling parameters used to execute the decoupling strategy are calculated, and the decoupling strategy is executed according to the decoupling parameters to complete the control handover.

2. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 1, characterized in that, The friction distribution curve includes: A one-dimensional thermal potential energy coordinate system is established by selecting the geometric center section where the feed inlet of the extruder barrel is located as the origin of the coordinate system. The coordinate axes of the thermal potential energy coordinate system are parallel to the central axis of the extruder barrel. Raw temperature data with location tags is collected on the extruder barrel using distributed optical fiber. The raw temperature data is then smoothly reconstructed to generate a distribution curve along the process. The smooth reconstruction adopts a piecewise polynomial fitting method based on physical continuity constraints. The mathematical expression of the distribution curve along the process is a piecewise cubic function. The mathematical expression uses the position coordinate variable in the thermal potential energy coordinate system as the independent variable. The constraint condition is that the function value, first derivative and second derivative of the distribution curve along the process are continuous at each original temperature data position. The position coordinate variable represents the absolute physical coordinate of the extruder barrel along the material extrusion direction.

3. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 2, characterized in that, The confirmed location of the shear heat core includes: By taking the first and second derivatives of the distribution curve along the friction with respect to the position coordinate variables, the friction gradient curve and the friction thermal curvature curve are obtained respectively. Traverse the gradient curve along the process and search for regions that simultaneously satisfy feature one and feature two. Feature one is that the function value on the gradient curve along the process is greater than the sum of the preset baseline negative gradient line and the preset gradient anomaly threshold. Feature two is that the gradient curve along the process exhibits an asymmetric isolated peak shape that first rises steeply and then falls slowly. Once a region that simultaneously satisfies both feature one and feature two is found, the zero-crossing point of the thermal curvature curve along the path is obtained, and the position of the zero-crossing point in the thermal potential energy coordinate system is marked as the candidate thermal core position. Obtain the function values ​​of the distribution curve along the path at the candidate heat core position within the current and multiple consecutive data output cycles, and construct a time-temperature sequence; perform linear regression fitting on the time-temperature sequence to obtain the slope of the fitted line, i.e. the temperature rise rate; When the temperature rise rate is greater than the preset pure thermal conduction temperature rise threshold, the candidate heat core location is confirmed as the shear heat core location.

4. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 3, characterized in that, The generated thermal energy characteristic report includes: A dynamic domain radius function is constructed by obtaining the location of the shear heat core inside the extruder barrel and the real-time screw speed. In the thermal potential energy coordinate system, with the shear heat core position as the center, the upstream and downstream boundaries of the high potential well interval are defined by the dynamic domain radius function, and the average thermal potential energy is obtained by integrating the distribution curve along the path within the high potential well interval. The upstream and downstream boundaries, along with the average thermal potential energy and the coordinate values ​​of the shear heat core location in the thermal potential energy coordinate system, are combined to obtain a thermal energy characteristic report.

5. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 4, characterized in that, The construction of the rheological response coordinate system includes: Analyze the thermal energy characteristic report, extract the upstream and downstream boundaries of the high potential well region in the thermal potential energy coordinate system, and obtain the physical actuators corresponding to the high potential well region. Based on the physical actuator, a standardized control action signal and rheological feedback signal are defined. The first derivative of the control action signal is obtained to obtain the control input rate of change; the first derivative of the rheological feedback signal is obtained to obtain the rheological feedback rate of change. A two-dimensional Cartesian coordinate system, namely the rheological response coordinate system, is established with the control input rate of change on the horizontal axis and the rheological feedback rate of change on the vertical axis. The control input rate of change and the rheological feedback rate of change are projected as an ordered pair onto the rheological response coordinate system to form the operating state point.

6. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 5, characterized in that, The rheological rhombic target region includes: Four vertices are marked in the rheological response coordinate system, namely the upper limit point of viscosity fluctuation, the slippage limit point, the thermal response boundary point, and the deadlock critical point. The upper limit point of viscosity fluctuation corresponds to the maximum positive value of the rheological feedback change rate caused by the inherent randomness of the extrusion process when the control input change rate is zero. It is located on the positive half-axis of the Y-axis of the rheological response coordinate system. The slippage limit point corresponds to the minimum negative value of the rheological feedback change rate that can be achieved when the rheological feedback signal drops sharply due to the wall slippage of the melt on the inner wall of the extruder barrel. It is located on the negative half-axis of the Y-axis of the rheological response coordinate system. Connecting the upper limit point of viscous fluctuation, the deadlock critical point, the slippage limit point, and the thermal response boundary point in sequence forms an asymmetric closed region, namely the rheological rhomboid target region.

7. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 6, characterized in that, The obtained rheological state determination results include: Real-time monitoring of the positional relationship between the operating status points and the rheological rhomboid target area; If the running state point falls outside the rheological rhomboid target area and is simultaneously located above the line segment connecting the upper limit point of viscous fluctuation and the deadlock critical point in the rheological response coordinate system, i.e. the upper right region of the first quadrant, a rheological state determination result marking the shear deadlock state is generated. If the operating state point is located inside the rheological rhombus target region, or outside the rheological rhombus target region but in the second or third quadrant, a rheological state determination result marked as a normal temperature control state is generated.

8. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 7, characterized in that, The decoupling parameters include: Calculate the vertical Euclidean distance from the running state point to the upper right boundary of the rheological rhomboid target area, and define the vertical Euclidean distance as the deadlock depth. The upper right boundary refers to the line segment connecting the upper limit point of viscous fluctuation and the deadlock critical point. Based on the deadlock depth, a fixed pulse reference period is set, and two core time parameters constituting the pulse reference period are calculated, namely the release period duration and the inhibition period duration. The pulse reference period, release period duration, and inhibition period duration are the decoupling parameters.

9. The extruder shear heat monitoring and control method based on distributed optical fiber as described in claim 8, characterized in that, The execution decoupling strategy includes: The execution of the decoupling strategy is divided into two operations: heating up to reduce viscosity and rapid heat dissipation. The temperature rise and viscosity reduction operation involves setting the cooling output of the hardware unit responsible for heat dissipation in the physical actuator to zero during the release period, while simultaneously sending a command to the main motor responsible for driving the screw rotation to reduce the real-time screw speed. The rapid heat dissipation operation follows immediately after the release period ends. During the suppression period, the cooling output of the hardware unit responsible for heat dissipation in the physical actuator is turned on to its maximum value to form a strong cooling pulse, while simultaneously restoring the real-time screw speed to its value before reduction. While implementing the decoupling strategy, a safety counter is set to continuously monitor the position of the operating status point in the rheological response coordinate system. If the operating status point falls into the rheological rhomboid target area at the end of the pulse reference period, the safety counter is incremented by one; otherwise, it is cleared to zero. When the count value of the safety counter reaches the preset safety threshold, it is determined that the shear deadlock state has been released, and the reverse pulse decoupling control is terminated.

10. A distributed optical fiber-based extruder shear heat monitoring and control system, used to implement the distributed optical fiber-based extruder shear heat monitoring and control method according to any one of claims 1-9, characterized in that, The system includes: Thermal energy feature sensing module: used to acquire raw temperature data distributed along the entire length of the extruder barrel, smooth and reconstruct the raw temperature data to obtain the along-path distribution curve characterizing the thermal state of the extruder barrel, perform morphological recognition on the along-path distribution curve to confirm the location of the shear heat core, construct a dynamic domain radius function based on the location of the shear heat core, delineate the high potential well interval according to the dynamic domain radius function, quantify the energy state of the high potential well interval to generate a thermal energy feature report; Rheological deadlock identification module: It is used to construct a rheological response coordinate system based on the thermal energy characteristic report, delineate a rheological rhomboid target area in the rheological response coordinate system, perform positional relationship judgment on the rheological rhomboid target area, and obtain the rheological state judgment result; Reverse decoupling control module: It is used to formulate reverse pulse decoupling control based on the rheological state determination result, calculate the decoupling parameters used to execute the decoupling strategy, execute the decoupling strategy according to the decoupling parameters, and complete the control switch.

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