Preparation process of low-shrinkage high-pressure-resistant cable protection pipe

Abstract

The application belongs to the field of high-performance polypropylene, and provides a preparation process of a low-shrinkage high-pressure-resistant cable protection pipe, which comprises the following steps: simultaneously collecting screw torque fluctuation, machine cylinder subsection pressure gradient, melt outlet transient temperature field and melt resistance change signal to form working condition combination parameters; generating screw function area flow structure response parameters according to the structure division of screw compression section, transition section and mixing section; according to the distribution gradient of the screw function area flow structure response parameters in the axial direction of the screw, the machine cylinder subsection temperature control gradient, the back pressure control threshold and the mixing element equivalent shear strength are further linked and adjusted; the adjusted process parameters are applied to the extrusion molding process, and the filler orientation structure distribution in the pipe wall section is output; and the filler orientation structure distribution in the pipe wall section and the historical process parameter data are subjected to differential analysis to form process input parameters for the next production cycle.

Description

Technical Field

[0001] This invention belongs to the field of high-performance polypropylene, specifically a process for preparing a low-shrinkage, high-pressure-resistant cable protection tube. Background Technology

[0002] In practical applications, cable protection pipes need to be designed differently between high pressure resistance and high toughness according to the usage scenario. Existing technologies usually improve the rigidity of materials by increasing the content of inorganic hard fillers, thereby enhancing pressure resistance. However, as the filler ratio increases, the uneven shrinkage of materials intensifies, and the low shrinkage performance decreases significantly. Therefore, there is usually an unavoidable trade-off between improving pressure resistance and shrinkage degradation.

[0003] However, this trade-off is not only determined by the formulation ratio, but also by the spatial distribution evolution of the filler during the screw extrusion process. During extrusion, the transient flow of the material in the transition compression section and the mixing section will cause changes in the uniformity of filler dispersion and orientation behavior, and affect the stress release path during the cooling process. Furthermore, the changes in melt rheological properties under different formulation conditions will also have a reverse effect on the migration and redistribution behavior of the filler, so that different formulations still exhibit different microstructure formation paths under the same process parameters. Thus, under the same production process conditions, different formulation systems will still lead to differences in the filler distribution state, which reduces the consistency of the shrinkage response of the pipe during the cooling and shrinkage stage, making it difficult to achieve stable dimensional shrinkage control. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0005] The technical solution adopted by this invention to solve its technical problem is: The screw torque fluctuation, barrel segment pressure gradient, melt outlet transient temperature field, and melt resistance change signals are collected synchronously. The above sampled signals are then processed by time reconstruction and phase alignment to form a combination of working condition parameters for characterizing the melt flow state in the transition area from the compression section to the mixing section. Based on the combined operating parameters, according to the structural division of the screw compression section, transition section and mixing section, the changes in melt shear strength in each functional zone are identified by zone, and the flow state difference parameters corresponding to each screw functional zone are output. Based on the influence of the shear strength change between the compression section and the mixing section on the packing migration hysteresis behavior, the flow state difference parameters are corrected by section, and the flow structure response parameters of the screw functional zone are generated. Based on the distribution gradient of the flow structure response parameters of the screw functional areas in the screw axial direction, the screw functional areas are divided into zones for identification, the structural state difference values ​​corresponding to each functional area are obtained, and the process control direction of each functional area of ​​the screw is determined according to the structural state difference values. Then, the temperature control gradient of the barrel segment, the back pressure control threshold and the equivalent shear strength of the mixing elements are adjusted in a coordinated manner. The adjusted process parameters are applied to the extrusion molding process, and the temperature of the cooling medium is controlled in stages along the radial direction after the tube body is formed. The radial temperature drop rate sequence is collected simultaneously. Based on this, a layered mapping analysis is carried out on the tube wall section to analyze the freezing state of each layer. Based on the distribution of the freezing state of the structure, the distribution of the filler orientation structure in the tube wall section is output. Based on the differential analysis of the packing orientation structure distribution in the pipe wall cross section and historical process parameter data, the structural offset is determined, and the material premixing ratio, screw extrusion parameters and cooling control parameters are iteratively corrected accordingly to form the process input parameters for the next production cycle.

[0006] As a further aspect of the present invention: The process of generating the operating condition combination parameters to characterize the melt flow state in the transition region from the compression section to the mixing section is as follows: Torque sensing units and pressure sampling units are installed in the feeding section, compression section and mixing section of the screw extruder, respectively, and a transient temperature acquisition array and melt resistance detection module are installed at the barrel outlet. Synchronous calibration is performed on various sensor signals according to the sampling timestamp, and the feeding end is used as the reference time zero point to rearrange the torque fluctuation signal, pressure gradient signal, temperature field change signal and resistance change signal in time sequence. Phase mapping processing is performed on various signals based on the screw rotation cycle, and signal segments corresponding to different functional areas are aligned and spliced ​​together. The aligned multi-source signals are windowed and segmented to extract the signal set of the transition zone between the compression section and the mixing section, and to construct the working condition combination parameters characterizing the changes in the melt flow state.

[0007] The process of outputting the flow state difference parameters corresponding to each screw functional region is as follows: Based on the geometric division of the screw structure, the working condition combination parameters are mapped to the corresponding spatial intervals of the compression section, transition section, and mixing section; The coupling characteristics of torque fluctuation amplitude and pressure gradient change rate in each functional zone are calculated separately and used as a characterization of shear strength change. By comparing the differences in shear strength between different functional regions, the locations of abrupt changes at the boundaries of the functional regions are extracted. The shear intensity distribution results within each functional zone are normalized, and the difference parameters used to characterize the degree of non-uniformity of the flow state in each screw functional zone are output.

[0008] The process of generating the flow structure response parameters of the screw functional region is as follows: Identify the shear strength abrupt change intervals between the compression section and the transition section, and between the transition section and the mixing section, and extract the melt resistance change response within the corresponding time window; Based on the time misalignment between the melt resistance change signal and the barrel pressure gradient change signal, the lag time window of the resistance response relative to the shear disturbance is extracted. The slope of the resistance change within the lag time window is integrated and normalized by combining it with the corresponding shear strength change rate to construct a delay factor characterizing the degree of lag in the migration response of the packing under shear drive. The migration lag factor is introduced into the flow state difference parameter of each functional zone to perform weighted correction on the local parameters of the abrupt change interval; The modified functional region parameters are continuously smoothed to generate screw functional region flow structure response parameters that characterize the internal structural response of the melt.

[0009] The process of obtaining the structural state difference values ​​corresponding to each functional area is as follows: Equally spaced sampling subdivision units are established along the screw axis to reconstruct the flow structure response parameters through spatial interpolation. Calculate the gradient rate of change of response parameters between adjacent subdivided units to form an axially distributed gradient sequence; The boundaries of functional zones are defined based on the continuous rising or falling intervals in the gradient sequence, and the structural boundary positions of each functional zone are determined. Statistical analysis is performed on the dispersion of response parameters in different functional zones, and the structural state difference values ​​corresponding to each functional zone are output.

[0010] The process of linking and adjusting the segmented temperature control gradient of the barrel, the back pressure control threshold, and the equivalent shear strength of the mixing elements is as follows: The structural state differences of each functional zone are spatially mapped along the screw axis to obtain the axial distribution results reflecting the degree of deviation of the flow structure, and the structural abrupt change zone and stable zone are identified based on the change characteristics. Within the structural abrupt change region, the structural state difference value is calculated in correspondence with the melt shear response characteristics to generate a shear control weight factor for characterizing the control intensity of each functional region. The segmented temperature control gradient of the barrel is corrected based on the shear control weight factor, and the back pressure control threshold is updated by interval mapping in combination with the back pressure response characteristics of each interval, thus forming the axial shear action distribution. The spatial migration trajectory of the packing in the melt is simultaneously characterized based on the distribution of axial shear action, and the dispersion evolution state of the packing along the screw direction is obtained. For the functional area at the end of the screw, the insufficient amount of packing dispersion is calculated based on the deviation between the dispersion evolution state and the target uniform distribution state. This is then decomposed into two types of control gaps: insufficient shearing action and insufficient residence time. Based on this, the equivalent shearing action intensity of the mixing elements and the axial residence time of the material are adjusted accordingly.

[0011] The process of analyzing the frozen state of each layer of the structure is as follows: The adjusted process parameters are applied to the extrusion molding process. After the tube body is formed, a graded cooling medium control unit is set along the radial direction, and the inner, middle and outer cooling areas are divided according to the tube wall thickness. Different temperature gradients of cooling medium were applied to each cooling zone, and the rate of temperature decrease in each zone over time was recorded. Based on the correspondence between the temperature drop rate in each region and the pipe wall thickness distribution, a mapping relationship between the radial temperature drop rate sequence and the pipe wall structure distribution is constructed. The structural freezing interface is defined based on the inflection point of the temperature drop rate, and the transformation process of each layer of material from a fluid state to a solidified state is obtained.

[0012] The process of packing orientation structure distribution within the cross-section of the output pipe wall is as follows: Based on the distribution of the frozen state of the structure, the frozen state of each radial layer is spatially superimposed to form a frozen structure map of the pipe wall section; Based on the differences in freezing rate in different regions of the frozen structure map, the shear residual distribution characteristics of the corresponding regions are extracted, and the orientation of the filler during the melt flow process is determined accordingly. Based on the orientation of the filler, the angular quantification analysis of the orientation changes between each radial layer is performed, the interlayer orientation deviation value is calculated, and a continuously recursive filler orientation gradient distribution sequence is formed. Based on the packing orientation gradient distribution sequence, the radial orientation structure distribution of the packing within the pipe wall cross section is output.

[0013] The process of determining the structural offset is as follows: Retrieve screw parameters, temperature control parameters, and cooling parameters corresponding to historical production batches, and extract standard filler orientation structure data for the corresponding batches; The current batch of packing orientation structure distribution is compared with the historical standard packing orientation structure data layer by layer, and corresponding matching is performed according to the radial layer position. Within each radial layer, the orientation angle deviation, interlayer orientation difference, and radial distribution consistency difference are calculated respectively. The above differences are weighted and merged to obtain the structural offset, which is used to characterize the degree of difference between the current structure and the historical standard structure.

[0014] The process of generating the process input parameters for the next production cycle is as follows: Based on the structural offset, the packing dispersion dimension, axial flow consistency dimension, and radial freezing consistency dimension are decomposed into components to obtain the offset contribution of each dimension. The offset contribution of each dimension is matched with the response coefficients of the material system, screw extrusion system and cooling system to obtain the corresponding parameter correction amount; When the contribution of the filler dispersion dimension offset exceeds the set range, the premixing ratio of elastomer toughening agent and inorganic filler is adjusted according to the parameter correction amount. When the contribution of the axial flow consistency dimension offset shifts, the screw speed, back pressure and barrel temperature control gradient are adjusted synchronously according to the corresponding correction amount. When the radial freezing consistency dimension offset contribution exceeds the threshold, the cooling medium temperature distribution and spray flow configuration are adjusted according to the correction amount. The correction values ​​of parameters in each dimension are summarized to generate the process input parameters for the next production cycle.

[0015] The beneficial effects of this invention are as follows: By reconstructing and aligning the time and phase of multiple signals, including screw torque, barrel pressure gradient, melt temperature field, and electrical response, during the extrusion molding process, continuous characterization of the melt flow state in the transition zone from the screw compression section to the mixing section is achieved. Furthermore, by combining the shear intensity variation characteristics of each functional zone, the flow structure response of different screw sections is identified and corrected in different zones. This allows process control to provide targeted compensation for structural abrupt changes between the compression and mixing sections, thereby improving the consistency of melt transport and filler dispersion. Based on this, gradient analysis of the screw axial structural state differences enables the coordinated optimization of barrel temperature control gradient, back pressure threshold, and shear capacity of mixing elements, making the rheological behavior of the melt more stable and controllable in different functional zones. This approach reduces structural dispersion caused by uneven local shearing and lag in filler migration. Simultaneously, by introducing radial graded cooling and temperature drop rate sequence analysis after molding, the freezing process of the pipe wall cross-section is mapped layer by layer. This refines the distribution pattern of filler orientation in each radial layer, resulting in higher resolution structural characterization. Finally, by comparing the current filler orientation structure distribution with historical process data, a structural offset feedback loop is formed. This allows for continuous iterative optimization of material premixing ratio, screw extrusion parameters, and cooling control parameters, thereby improving the overall uniformity and consistency of the pipe cross-section structure, reducing uneven shrinkage and local stress concentration, and enhancing the dimensional stability and pressure resistance reliability of the cable protection pipe under complex service conditions. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1This is a flowchart of the manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube provided in Embodiment 1 of the present invention; Figure 2 This is a schematic flowchart of the manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Example 1: Please refer to Figure 1-2 As shown in the figure, the manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to an embodiment of the present invention includes the following steps: Step S10: Synchronously collect screw torque fluctuation, barrel segment pressure gradient, melt outlet transient temperature field and melt resistance change signals, and perform time reconstruction and phase alignment processing on the above sampled signals to form working condition combination parameters for characterizing the melt flow state in the transition area from the compression section to the mixing section.

[0020] In step S10, the process of forming the working condition combination parameters for characterizing the melt flow state in the transition region from the compression section to the mixing section is as follows: Torque sensing units and pressure sampling units are installed in the feeding section, compression section, and mixing section of the screw extruder, respectively. A transient temperature acquisition array and a melt resistance detection module are installed at the barrel outlet. Embedded slots are formed on the outer wall of the barrel corresponding to the feeding section, compression section, and mixing section of the screw extruder, and torque sensing units and pressure sampling units are embedded in each slot. The torque sensing unit is linked to the screw drive shaft through a non-contact strain gauge structure to collect screw load fluctuation signals in real time. The pressure sampling unit adopts a segmented melt contact film structure and is installed in... At different axial positions on the inner wall of the barrel, local melt pressure gradient changes are acquired. At the barrel outlet, a transient temperature acquisition array is evenly distributed circumferentially. This array employs a hybrid structure of multi-point infrared and contact thermocouples to capture radial and circumferential temperature distribution changes during melt extrusion. Simultaneously, a melt resistance detection module is installed outside the outlet flow channel. This module uses a ring-shaped four-electrode non-contact layout: two sets of excitation electrodes and two sets of detection electrodes are alternately and equidistantly installed circumferentially outside the outlet flow channel. Each set of electrodes is a semi-circular arc plate with an arc length corresponding to 60 mm. The central angle is 10° and the axial width is 10mm. The four sets of electrodes are circumferentially spaced at 30°. A 2mm annular non-contact air gap is maintained between the inner wall of the electrode plate and the outer wall of the flow channel. Each electrode is made of Inconel 718 nickel-based alloy substrate and coated with a 0.5mm thick platinum layer. A 3mm thick polyimide insulating layer is set between the electrode and the barrel shell. Adjacent electrodes are circumferentially isolated by polyetheretherketone positioning brackets. The outer side is covered with a stainless steel shield and connected to the signal ground at a single point. During operation, a signal generator applies a frequency of 1MHz and a peak-to-peak value of 1... A 0V sinusoidal alternating voltage is demodulated and converted into the equivalent resistivity characteristic parameter of the melt through the differential voltage signal between the detection electrodes. The output voltage is in the millivolt range to reflect the changes in the packing dispersion and conductive path. The annular electrode assembly is tightly fixed to the outer wall of the outlet flow channel using a split flange structure. The electrode leads are connected to the acquisition controller via a high-temperature shielded cable. The torque sensing unit, pressure sampling unit, transient temperature acquisition array, and melt resistance detection module are all connected to the acquisition controller through a unified industrial bus to achieve synchronous acquisition and time alignment of multi-source data.

[0021] Synchronous calibration is performed on various sensor signals according to the sampling timestamp, and the feeding end is used as the reference time zero point. The torque fluctuation signal, pressure gradient signal, temperature field change signal, and resistance change signal are rearranged in time. All collected torque, pressure, temperature, and resistance signals are uniformly marked with high-precision timestamps, and the initial stable moment of torque at the feeding end is used as the system time zero point for time reference calibration of each channel signal. In specific implementation, interpolation resampling is performed on the sampling frequency differences of each sensor to uniformly map data from different sampling periods to an equal time interval sequence. At the same time, to address the phase drift problem caused by transmission delay, a sliding time window alignment algorithm is introduced to perform feature matching correction on the pressure peak point and torque fluctuation feature point, thereby achieving accurate rearrangement of multi-source signals on a unified time axis, making the changes of each physical quantity comparable and consistent at the same process moment.

[0022] Phase mapping processing is performed on various signals based on the screw rotation cycle, aligning and splicing signal segments corresponding to different functional areas. Real-time screw rotation speed signals are acquired and their periodic rotation reference is calculated. Each screw rotation cycle is divided into equal-angle phase intervals, which serve as phase mapping reference coordinates. Torque fluctuations, pressure gradients, temperature changes, and resistance response signals are projected onto the screw rotation phase coordinate system, ensuring that sampling points at different times correspond to the same phase position. Subsequently, according to the structural length ratios of the feeding section, compression section, and mixing section, the phase-mapped signals are functionally segmented and calibrated. Phase boundary alignment is then used to splice and reconstruct the signal segments corresponding to each functional area, forming a multi-source coupled signal sequence with spatial correspondence, achieving a one-to-one correspondence between process sections and signal characteristics.

[0023] The aligned multi-source signals are segmented into windows to extract the signal set of the transition zone between the compression and mixing sections, constructing a set of working condition combination parameters characterizing the changes in melt flow state. After completing time-series reconstruction and phase alignment, the multi-source fused signals are segmented using a sliding window method. The window length is determined based on the axial distance between the screw compression and mixing sections and the corresponding time of rotational speed, and an overlap step size is set to ensure the continuity of transition information. By calculating the changes in torque fluctuation amplitude, pressure gradient abruptness, temperature field gradient change rate, and resistance response drift within adjacent windows, signal segments with simultaneous multi-physical quantity coupling change characteristics are selected and defined as the signal set of the transition zone between the compression and mixing sections. Based on this, the multi-source feature parameters within each window are combined and encoded to form a set of working condition combination parameters that can uniformly characterize the evolution of melt flow state. These parameters serve as the input basis for subsequent flow state identification and structural evolution analysis, realizing a complete digital description of the melt behavior in the screw transition zone.

[0024] Step S20: Based on the combined operating parameters, according to the structural division of the screw compression section, transition section and mixing section, the change of melt shear strength in each functional area is identified by region, and the flow state difference parameters corresponding to each screw functional area are output. Based on the influence of the shear strength change between the compression section and the mixing section on the packing migration hysteresis behavior, the flow state difference parameters are corrected by section, and the flow structure response parameters of the screw functional area are generated.

[0025] In step S20, the process of outputting the flow state difference parameters corresponding to each screw functional region is as follows: Based on the screw structure geometry division results, the working condition combination parameters are mapped to the corresponding spatial intervals of the compression section, transition section, and mixing section. Based on the screw structure geometry division results, the axial length parameters of the screw compression section, transition section, and mixing section are input to the control system, and a corresponding spatial coordinate mapping model is established on the outer wall of the extruder barrel. In specific implementation, with the screw inlet end as the axial zero point, the barrel is equivalently segmented and calibrated according to the cumulative pitch length. The synchronously reconstructed working condition combination parameters are mapped to the corresponding spatial intervals according to the time-axial conversion relationship, so that the torque, pressure, temperature, and resistance data at each sampling moment can correspond to the specific functional area location, thereby forming a partitioned data set for the compression section, transition section, and mixing section, providing a spatial assignment basis for subsequent difference analysis.

[0026] The coupling characteristics of torque fluctuation amplitude and pressure gradient change rate in each functional zone are calculated separately as a characterization of shear strength change. After completing the data assignment for each functional zone, local statistical analysis is performed on the working condition combination parameters in the compression section, transition section, and mixing section to extract the synchronous change characteristics of torque fluctuation amplitude and barrel pressure gradient change rate. The torque fluctuation amplitude is obtained by the difference between the maximum and average values ​​within the sliding window, and the pressure gradient change rate is calculated by the time derivative of the pressure difference between adjacent axial measuring points. The two types of characteristics are weighted and coupled to form a characterization of local shear strength change, which reflects the strength of the combined effect of mechanical shear and flow resistance on the melt in different functional zones, and realizes the quantitative expression of the rheological state of different sections of the screw.

[0027] By comparing the differences in shear strength between different functional zones, the abrupt change locations at the boundaries of the functional zones are extracted. A lateral comparative analysis of the shear strength coupling characteristics between the compression, transition, and mixing sections is conducted. First, a shear strength distribution curve along the screw axis is constructed, and then the gradient of the characteristic difference between adjacent functional zones is calculated. When the gradient change exceeds a preset stability threshold, it is identified as a shear strength abrupt change point, and its specific axial position is determined using a local extremum detection algorithm. Furthermore, by combining the synchronous fluctuation characteristics of torque and pressure signals, a secondary verification of the abrupt change point is performed to eliminate random noise interference, thereby obtaining the true shear behavior transition locations at the boundaries of the functional zones and achieving accurate positioning of the abrupt change region in the flow state of the transition section.

[0028] The shear intensity distribution results within each functional zone are normalized to output a difference parameter characterizing the non-uniformity of the flow state in each screw functional zone. After obtaining the shear intensity distribution results within each functional zone, the distribution data of different functional zones are normalized to a uniform scale. The normalization is based on the standardization mapping of the extreme range and mean offset of the shear intensity in each interval, so that the data of different functional zones are in the same dimension space. Then, the dispersion of the shear intensity within each functional zone, including variance and local fluctuation coefficient, is calculated to characterize the non-uniformity of its flow state, and this non-uniformity is output as a difference parameter of the flow state in the functional zone. This parameter is used to directly reflect the difference in melt flow stability between the compression section, transition section and mixing section, providing a quantitative basis for subsequent process control.

[0029] In step S20, the process of generating the flow structure response parameters of the screw functional region is as follows: The shear strength abrupt change intervals between the compression section and the transition section, and between the transition section and the mixing section, are identified, and the melt resistance change response within the corresponding time window is extracted. Based on the obtained flow state difference parameters of each functional zone, continuous shear strength curves are established at the axial boundary positions between the compression section and the transition section, and between the transition section and the mixing section. The boundaries of the intervals where shear strength abrupt changes are identified through first-order difference and local extremum detection. In specific implementation, the shear strength change rate is calculated by moving a fixed sliding window along the screw axis. When the change rate exceeds a set threshold and continues for a certain sampling length, it is determined to be a shear abrupt change interval. Subsequently, the melt resistance change signal within the synchronous time window is extracted within the corresponding abrupt change interval, and the resistance signal is bandpass filtered to remove high-frequency noise and process disturbance interference, thereby obtaining a resistance response sequence that strictly corresponds to the shear abrupt change event, providing basic data for subsequent hysteresis analysis.

[0030] Based on the temporal misalignment between the melt resistance change signal and the barrel pressure gradient change signal, a lag time window of the resistance response relative to shear disturbance is extracted. The slope of the resistance change within the lag time window is integrated and normalized by combining it with the corresponding shear strength change rate to construct a delay factor characterizing the degree of lag in the packing migration response under shear drive. After obtaining the shear abrupt change interval and the corresponding resistance response sequence, the barrel pressure gradient change signal is used as the shear disturbance reference signal. Time correlation analysis is performed between the pressure gradient change signal and the melt resistance change signal, and the time misalignment between the two is calculated using a cross-correlation function to determine the lag time window of the resistance response relative to shear disturbance. Furthermore, the local slope change sequence of the resistance change curve is extracted within this lag window, and the slope change is accumulated by numerical integration to characterize the overall evolution trend of the resistance response. At the same time, the integration result is normalized and matched with the corresponding shear strength change rate to eliminate the influence of different operating scales. Finally, a delay factor characterizing the degree of lag in the packing migration response under shear drive is constructed. This factor is used to characterize the dynamic lag characteristics of the internal structure adjustment of the melt relative to the external shear disturbance.

[0031] A migration lag factor is introduced into the flow state difference parameters of each functional zone to perform weighted correction on the local parameters in the abrupt change interval. After obtaining the delay factor, it is introduced as a correction weight into the flow state difference parameter system of each functional zone to dynamically adjust the local parameters within the shear abrupt change interval. In specific implementation, the original difference parameters are multiplied by a correction coefficient positively correlated with the delay factor. When the delay factor is large, the weight of the flow state instability in the corresponding region is increased, thereby strengthening the characterization of the packing migration lag effect; when the delay factor is small, the weight of the local disturbance influence is reduced. In this way, the asynchronous relationship between "mechanical disturbance - electrical response - structural migration" in the shear abrupt change interval is compensated and corrected, making the flow state characterization of the functional zone closer to the actual internal structural evolution process of the melt.

[0032] The modified functional zone parameters are continuously smoothed to generate screw functional zone flow structure response parameters characterizing the internal structural response of the melt. The parameters of each functional zone after retardation factor correction are then continuously smoothed axially, specifically using a smoothing method combining sliding weighted average and Gaussian kernel function. Transitional corrections are applied to parameter abrupt changes at functional zone boundaries, ensuring a continuous variation in parameter distribution between the compression, transition, and mixing sections. Subsequently, an overall flow structure response curve is constructed based on the smoothed parameters to characterize the structural evolution of the melt throughout the screw functional zone. The final output screw functional zone flow structure response parameters comprehensively reflect the coupling relationship between shear abrupt changes, resistive hysteresis, and structural migration, achieving a holistic quantitative description of the internal structural response behavior of the melt and providing a unified input basis for subsequent process feedback control.

[0033] Step S30: Based on the distribution gradient of the flow structure response parameters of the screw functional areas in the screw axial direction, the screw functional areas are divided into zones for identification, the structural state difference values ​​corresponding to each functional area are obtained, and the process control direction of each functional area of ​​the screw is determined according to the structural state difference values. Then, the barrel segment temperature control gradient, back pressure control threshold and equivalent shear strength of the mixing elements are adjusted in a coordinated manner.

[0034] In step S30, the process of obtaining the structural state difference values ​​corresponding to each functional area is as follows: Equally spaced sampling subdivision units are established along the screw axis to reconstruct the flow structure response parameters through spatial interpolation. Starting from the inlet end along the screw axis, the entire extrusion area is divided into equally spaced subdivision units based on the effective working length of the screw. The length of each subdivision unit is determined by a preset spatial resolution, and a unique spatial index identifier is established through coding. Subsequently, the obtained flow structure response parameters of the screw functional area are converted into spatially distributed data according to the time-axial mapping relationship, and cubic spline interpolation or local weighted regression is used to reconstruct the spatial continuity of discrete sampling points, so that the response parameters form a continuously changing surface in the axial direction. In this way, the originally discrete operating condition response data is transformed into a spatially consistent structural response field, providing a unified data foundation for subsequent gradient analysis.

[0035] The gradient change rate of the response parameters between adjacent subdivided units is calculated to form an axially distributed gradient sequence. After spatial reconstruction, the structural response parameters between adjacent subdivided units are differentially calculated to obtain the axial local variation. The gradient change rate is then calculated by dividing by the unit spacing to form a continuous axially distributed gradient sequence. In practice, a central difference algorithm can be used to improve the gradient calculation accuracy, and the gradient sequence can be lightly smoothed to eliminate the influence of random noise. This gradient sequence is used to characterize the intensity and direction of the change in the melt structure response in the screw axial direction, thus providing a basic criterion for functional area boundary identification.

[0036] Functional zone boundaries are defined based on continuously rising or falling intervals in the gradient sequence, determining the structural boundary positions of each functional zone. Continuity analysis is performed on the axially distributed gradient sequence to identify intervals that continuously rise or fall monotonically, and monotonically rising intervals that meet the duration threshold are selected as candidate structural evolution segments. Further, gradient sign change points and extreme point positions are detected in the candidate segments. When a change inflection point occurs from positive to negative or from negative to positive, it is determined as a candidate point for the functional zone boundary. Subsequently, the candidate boundaries are further screened based on the local fluctuation amplitude of the structural response parameters to eliminate pseudo-abrupt points caused by noise, thereby determining the actual structural boundary positions of the compression section, transition section, and mixing section, achieving automatic functional zone division based on data-driven principles.

[0037] Statistical analysis is performed on the dispersion of response parameters in different functional zones, outputting the structural state difference values ​​corresponding to each functional zone. After completing the functional zone division, statistical analysis is performed on the structural response parameters within each functional zone. First, the mean and standard deviation of the parameters within the interval are calculated, and then the non-uniformity of the data distribution is quantitatively characterized based on the coefficient of variation or variance. In specific implementation, standard deviation normalization can be used to make different functional zones comparable, thereby avoiding the influence of scale differences on the judgment results. Finally, the dispersion within each functional zone is output as the structural state difference value. This difference value is used to reflect the degree of difference in melt structure stability and uniformity within different screw functional zones, providing a quantitative basis for subsequent process parameter optimization.

[0038] In step S30, the process of adjusting the segmented temperature control gradient of the barrel, the back pressure control threshold, and the equivalent shear strength of the mixing elements in a coordinated manner is as follows: The structural state differences of each functional zone are spatially mapped along the screw axis to obtain an axial distribution result reflecting the degree of deviation of the flow structure. Based on the change characteristics, structural abrupt change zones and stable zones are identified. The calculated structural state differences of each functional zone are spatially mapped along the screw axis. During the mapping process, the screw inlet end is used as the reference zero point. The difference values ​​are assigned to the corresponding axial positions point by point according to the equally spaced subdivision units to form a continuous axial distribution curve. Subsequently, based on the change characteristics of this curve, zone identification is performed. By calculating the local slope and its sign change, the area where the absolute value of the slope is continuously higher than the set threshold is identified as a structural abrupt change zone, while the area where the slope is maintained in a low fluctuation range for a long time is identified as a stable zone. Thus, the structural state zoning results along the screw axis are obtained, providing a spatial basis for subsequent regulation.

[0039] Within the structural abrupt change zone, the structural state difference values ​​are correlated with the melt shear response characteristics to generate shear control weight factors that characterize the control intensity of each functional zone. Within the structural abrupt change zone, the structural state difference values ​​are correlated with the melt shear response characteristics, where the shear response characteristics are characterized by the coupling result of torque fluctuation amplitude and pressure gradient change rate. By constructing a difference-shear response mapping model, the two are normalized and matched, and a local sensitivity coefficient is introduced to amplify or suppress the response intensity within the abrupt change zone, thereby generating shear control weight factors that characterize the control intensity of each functional zone. This factor quantifies the sensitivity of different axial positions to shear behavior, providing a weighting basis for segmented control.

[0040] The segmented temperature control gradient of the barrel is corrected based on the shear control weighting factor, and the back pressure control threshold is updated by interval mapping in combination with the back pressure response characteristics of each interval, thus forming an axial shear effect distribution. Based on the shear control weighting factor, the segmented temperature control system of the barrel is corrected in segments, and the set temperature gradient of the temperature control segment corresponding to the high-weight abrupt change zone is refined and adjusted. The directional adjustment of melt viscosity change is achieved by increasing or decreasing the local temperature control slope. At the same time, the back pressure-flow state mapping relationship is established by combining the back pressure response characteristics of each axial interval, and the back pressure control threshold is updated in intervals. This makes the high shear region correspond to a higher back pressure constraint to enhance the mixing strength, while the low shear region maintains a relatively stable pressure condition, thus forming an axial shear effect distribution.

[0041] The spatial migration trajectory of the packing in the melt is synchronously characterized based on the axial shear distribution, yielding the dispersion evolution state of the packing along the screw direction. Based on the aforementioned axial shear distribution, the migration behavior of the packing in the melt is synchronously modeled, treating the shear intensity gradient as the driving field and the packing as discrete particles moving with the flow field. By constructing an axial migration path sequence, the motion trajectory of the packing in each functional zone is continuously tracked and statistically analyzed, thereby obtaining the dispersion evolution state of the packing in the screw axial direction. This state is used to characterize the process of the packing transforming from an agglomerated state to a uniformly distributed state and its spatial distribution law.

[0042] For the screw end functional area, based on the deviation between the dispersion evolution state and the target uniform distribution state, the packing dispersion deficiency is calculated and decomposed into two control gaps: insufficient shearing and insufficient residence time. Based on this, the equivalent shearing intensity of the mixing elements and the axial residence time of the material are adjusted accordingly. For the screw end mixing functional area, the difference between the current packing dispersion evolution state and the target uniform distribution state is compared, and the packing dispersion deficiency is obtained by calculating the spatial distribution error. This deficiency is further decomposed into two control gaps: insufficient shearing, manifested by insufficient local shear field intensity; and insufficient residence time, manifested by a shorter average residence time of the material in the end region. For these two control gaps, adjustments are made by changing the mixing element configuration during batch-to-batch shutdowns. That is, after the current production batch ends, the calculated packing dispersion deficiency and its decomposition results are used as the process input parameters for the next production cycle. The process input parameters include a mixing element configuration scheme, specifically the shear element density level and meshing angle setting value. According to this scheme, the mixing element is replaced with the corresponding specification before the next batch of production to achieve coordinated optimization and control of shear intensity and residence time. As a specific implementation of this scheme, the shear element density level in the mixing element configuration scheme is achieved by adjusting the number of shear elements per unit length, the meshing angle setting value is achieved by selecting kneading block elements with different staggered angles, and the residence time is adjusted by selecting flow-blocking elements with different lengths or different helix angles. After the operator completes the replacement and confirmation of the mixing elements between batches according to the process parameter adjustment instructions output by the acquisition controller, the next production cycle is started. The torque sensing unit, pressure sampling unit, transient temperature acquisition array, and melt resistance detection module mentioned above are all connected to the acquisition controller through a unified industrial bus to achieve synchronous acquisition and time alignment of multi-source data.

[0043] Step S40: Apply the adjusted process parameters to the extrusion molding process, and after the tube body is formed, control the temperature of the cooling medium in stages along the radial direction. Simultaneously collect the radial temperature drop rate sequence, and conduct a layered mapping analysis on the tube wall cross section accordingly to analyze the freezing state of each layer structure. Based on the distribution results of the structural freezing state, output the distribution of the filler orientation structure in the tube wall cross section.

[0044] In step S40, the process of analyzing the frozen state of each layer of the structure is as follows: The adjusted process parameters are applied to the extrusion molding process. After the tube body is formed, a graded cooling medium control unit is set along the radial direction, and the tube wall thickness direction is divided into inner, middle and outer cooling areas. After the tube body is extruded, a graded cooling medium control unit is arranged on the outside of the tube wall in the radial direction. The control unit includes an annular partitioned cooling sleeve and an independent temperature control circulation loop, and the tube wall thickness direction is divided into three radial cooling areas: inner, middle and outer, by an axial positioning fixture. In specific implementation, the layer ratio is preset according to the tube wall thickness. The inner layer is set as a high thermal gradient area close to the inner wall of the tube, the middle layer is a transitional slow cooling area, and the outer layer is a rapid heat dissipation area. Each area corresponds to an independent temperature control execution module, thereby realizing a partitioned controllable cooling structure in the radial direction.

[0045] Different temperature gradients of cooling media are applied to each cooling zone, and the rate of temperature decrease in each zone over time is recorded. Different set temperature gradients of cooling media are applied to each radial cooling zone; the cooling media can be circulating water or temperature-controlled oil. The inlet temperature and flow rate of each zone are adjusted via independent temperature-controlled valves to create differentiated cooling intensities. During the cooling process, a multi-point temperature sensor array is deployed in each radial zone, and temperature change data over time is collected in real time using thermocouples or infrared thermometry, recording the temperature decrease rate sequence for each zone. A unified data acquisition system synchronously records the temperature drop curves of different zones, ensuring temporal consistency and comparability of the temperature evolution process across radial layers.

[0046] Based on the correspondence between the temperature drop rate of each region and the pipe wall thickness distribution, a mapping relationship between the radial temperature drop rate sequence and the pipe wall structure distribution is constructed. The temperature drop rate of each radial cooling region is spatially correlated with the corresponding pipe wall thickness position to establish a radial temperature drop rate sequence, where each sampling point contains a three-dimensional information structure of "radial position - time - temperature drop rate". Subsequently, interpolation reconstruction is used to process the discrete temperature drop data into a continuous function to form a temperature drop distribution function in the pipe wall thickness direction. This function is then correlated with the thermal conductivity characteristics of the material during the transition from the molten state to the solidified state, thereby constructing a mapping relationship between the radial temperature drop rate sequence and the pipe wall structure distribution, and realizing a visual representation of the cooling behavior of different layers of material.

[0047] The structural freezing interface is defined based on the inflection point of the temperature drop rate, and the transition process of each layer of material from a fluid state to a solid state is obtained. Based on the radial temperature drop rate curve, its first-order rate of change is calculated. When the temperature drop rate shows an inflection point from a rapid decrease to a slowdown or plateau, it is determined to be the location of the structural freezing interface. The temperature drop curve is locally fitted using the sliding window method, and the inflection point of the derivative change sign is identified, thereby determining the boundary position of the transition from a fluid state to a solid state for the inner, middle, and outer layers of material. Furthermore, the freezing interface is corrected by combining the temperature stabilization time interval of each layer, and finally the complete solidification evolution process of each layer of material is obtained, realizing the layered analysis of the radial structural freezing state of the pipe wall.

[0048] In step S40, the process of distributing the packing orientation structure within the cross-section of the output pipe wall is as follows: Based on the distribution of the frozen state of the structure, the frozen states of each radial layer are spatially superimposed to form a frozen structure map of the pipe wall cross section. Based on the obtained distribution of the frozen state, the frozen state data of each radial layer (inner, middle, and outer layers) are first spatially aligned. A polar coordinate system is established with the geometric center of the pipe wall cross section as the reference, and the frozen state of each layer is mapped to its corresponding radial spatial position. Subsequently, interlayer interpolation and spatial superposition are used to continuously fuse the frozen states of different radial regions, eliminating the interlayer discrete boundary effect and forming a frozen structure map of the pipe wall cross section with continuous spatial expression characteristics. In specific implementation, this map expresses the freezing intensity distribution in the form of a two-dimensional cross-sectional matrix, realizing the spatial reconstruction of the overall solidified structure of the pipe wall.

[0049] Based on the differences in freezing rates in different regions of the frozen structure map, the shear residual distribution characteristics of the corresponding regions are extracted, and the orientation of the filler during melt flow is determined accordingly. Based on the frozen structure map, local gradient analysis is performed on the differences in freezing rates in different regions. By calculating the rate of change of freezing rate between adjacent spatial units, regional freezing non-uniformity characteristics are extracted and used as a characterization of shear residual distribution. In practice, regions with higher freezing rates correspond to stronger shear residual retention, while regions with lower freezing rates correspond to shear relaxation regions. Based on this correspondence, combined with the consistency constraint between the melt flow direction and the shear gradient direction, the force deflection path of the filler in the melt is inferred, thereby determining the orientation of the filler in each region, realizing the process of inverting the filler orientation direction from thermal history information.

[0050] Based on the orientation of the filler, the angular quantification analysis of the orientation changes between each radial layer is performed to calculate the interlayer orientation deviation value, forming a continuously recursive filler orientation gradient distribution sequence. After determining the orientation of the filler, the angle between the orientation directions of adjacent radial layers is calculated. Taking the radial normal direction of the cross section as a reference, the angle between the main orientation direction of the filler and the reference direction is quantified to obtain the interlayer orientation deviation value. Subsequently, the deviation values ​​of each layer are recursively arranged according to the radial order from the inner layer to the outer layer to form a continuous filler orientation gradient distribution sequence. In specific implementation, the angular change rate is smoothed to avoid local outliers from interfering with the overall trend, thereby ensuring that the gradient sequence can truly reflect the layer-by-layer orientation evolution law of the filler in the radial direction.

[0051] Based on the packing orientation gradient distribution sequence, the radial orientation structure distribution of the packing within the pipe wall cross-section is output. Based on this sequence, the orientation variation trend of the packing within the entire pipe wall cross-section is reconstructed and analyzed, mapping the angular gradient variation to a radial spatial coordinate system to form a continuous distribution function. Further, interpolation reconstruction is used to process the discrete interlayer data into a continuous function, obtaining the distribution curve of the packing orientation as a function of radial position, thus outputting the complete orientation structure distribution result of the packing within the pipe wall cross-section. This result is used to characterize the spatial evolution law of the packing's transition from flow orientation to freezing orientation in the radial direction, achieving a holistic analysis of the internal microstructure of the pipe.

[0052] Step S50: Based on the difference analysis between the packing orientation structure distribution in the pipe wall cross section and historical process parameter data, determine the structural offset, and iteratively correct the material premixing ratio, screw extrusion parameters and cooling control parameters accordingly to form the process input parameters for the next production cycle.

[0053] In step S50, the process of determining the structural offset is as follows: The system retrieves screw parameters, temperature control parameters, and cooling parameters corresponding to historical production batches, and extracts standard packing orientation structure data for each batch. It also retrieves complete process parameter records for each historical production batch from the production database, including screw speed curves, barrel segment temperature control gradients, and cooling medium control parameters, and simultaneously extracts packing orientation structure data for each batch under stable operating conditions. In practice, historical data is filtered for operating conditions, selecting only batches that meet stable production conditions and have qualified product performance as standard samples. Their orientation structure data are then statistically averaged or weighted and fused to form a representative standard packing orientation structure benchmark model for subsequent comparative analysis with current batch data.

[0054] The current batch of packing orientation structure distribution is compared layer by layer with historical standard packing orientation structure data, and corresponding matching is performed according to the radial layer position. The current batch of packing orientation structure distribution is spatially aligned with historical standard packing orientation structure data, and the radial geometric center of the pipe wall is used as a unified reference benchmark. Layer by layer mapping and matching is performed according to the radial layer structure of the inner layer, middle layer and outer layer. In specific implementation, the consistency of layer position between different batches is ensured by dividing the layers with equal thickness, and interpolation resampling is used to uniformly correct the resolution difference, so that the current batch and the historical standard structure are comparable at the same radial position, thus providing a consistent data space basis for subsequent difference calculation.

[0055] Within each radial layer, the orientation angle deviation, interlayer orientation difference, and radial distribution consistency difference are calculated. After layer matching is completed, the filler orientation structure within each radial layer is compared and analyzed item by item, including three types of indicators: orientation angle deviation, interlayer orientation difference, and radial distribution consistency difference. In practice, the orientation angle deviation is obtained by calculating the orientation angle difference between the current batch and the standard model at the same radial position; the interlayer orientation difference is obtained by calculating the change in orientation direction between adjacent radial layers; and the radial distribution consistency difference is obtained by performing correlation coefficient or mean square error analysis on the entire radial orientation curve. The above three types of indicators together reflect the degree of local and overall deviation of the current batch structure from the standard structure.

[0056] The above-mentioned differences are weighted and merged to obtain a structural offset that characterizes the degree of difference between the current structure and the historical standard structure. After obtaining the multidimensional difference indexes of each radial layer, the orientation angle deviation, interlayer orientation difference, and radial distribution consistency difference are assigned preset or dynamically adjusted weight coefficients, and a linear weighted or normalized weighted fusion method is used for comprehensive calculation to obtain a unified structural offset. In specific implementation, the weight coefficients can be adaptively adjusted according to different process sensitivity parameters to enhance the responsiveness to key structural changes. The final output structural offset is used to characterize the overall deviation between the current batch of filler orientation structure and the historical standard structure, providing a quantitative basis for subsequent process parameter iteration and correction.

[0057] In step S50, the process of generating the process input parameters for the next production cycle is as follows: Based on the structural offset, the packing dispersion dimension, axial flow consistency dimension, and radial freezing consistency dimension are decomposed into components to obtain the offset contribution of each dimension. The calculated structural offset is then decomposed into three sub-quantities according to the packing dispersion characteristics, axial flow characteristics, and radial freezing characteristics: the offset contribution of the packing dispersion dimension, the offset contribution of the axial flow consistency dimension, and the offset contribution of the radial freezing consistency dimension. In practice, a mapping model between the structural offset and the three-dimensional feature space is established to separate and calculate the projection components of the offset in different feature directions, thereby obtaining the independent offset contribution value corresponding to each dimension, providing a basic input for subsequent targeted process correction.

[0058] The offset contribution of each dimension was matched with the response coefficients of the material system, screw extrusion system, and cooling system to obtain the corresponding parameter correction. After obtaining the offset contribution of each dimension, it was matched with the response coefficients of the material system, screw extrusion system, and cooling system respectively. The material system response coefficient is used to characterize the sensitivity of the formulation to structural changes. It is derived from: conducting step-by-step process parameter perturbation tests under standard process conditions for the current processing material system, measuring the rheological response of each formulation component under different shear rates and temperatures, and the structural characteristics of the final product. The mapping relationship between the material formulation parameters and the product structural indicators was established through regression analysis, and the gradient matrix of this mapping relationship is the material system response coefficient. The screw extrusion system response coefficient is used to characterize the mechanical shear and flow control capabilities. It is derived from: establishing the transmission between process variables such as screw speed, torque, and barrel temperature and melt pressure, temperature, and shear history based on screw geometric parameters and material conveying models through numerical simulation or empirical calibration. The transfer function's gain matrix is ​​the screw extrusion system response coefficient. The cooling system response coefficient characterizes the effect of the curing process on the structure retention capability. It is derived by setting temperature and pressure sampling points at different locations in the cooling section, collecting multiple sets of data corresponding to the cooling rate and the final product structure, and obtaining the sensitivity matrix of the cooling process parameters to the degree of structural freezing through multivariate regression or neural network fitting. This matrix is ​​the cooling system response coefficient. The three types of response coefficients are pre-established through offline calibration experiments and stored in the parameter library of the acquisition controller. During actual production, the corresponding coefficient matrix is ​​automatically called based on the current material batch information. In specific implementation, a multivariate linear or nonlinear mapping relationship model is constructed, and the offset contribution of each dimension is multiplied or weighted by the corresponding response coefficient to obtain the parameter correction amount corresponding to each system, realizing the conversion of offset into process adjustment amount. The torque sensing unit, pressure sampling unit, transient temperature acquisition array, and melt resistance detection module are all connected to the acquisition controller through a unified industrial bus to achieve synchronous acquisition and time alignment of multi-source data.

[0059] When the contribution of the filler dispersion dimension offset exceeds the set range, the premixing ratio of the elastomer toughening agent and the inorganic filler is adjusted according to the parameter correction amount. When the contribution of the filler dispersion dimension offset exceeds the preset threshold range, it is determined that there is uneven filler dispersion or agglomeration in the current batch. At this time, the premixing ratio of the elastomer toughening agent and the inorganic filler is adjusted according to the calculated material system parameter correction amount. In specific implementation, the toughening agent ratio can be increased to enhance the matrix flow and coating ability, or the inorganic filler particle size ratio can be adjusted to improve the dispersion uniformity. The high-speed shear mixing unit of the premixing equipment can be used to achieve uniform dispersion of the modified formula, thereby correcting the filler distribution deviation at the source.

[0060] When the contribution of the axial flow consistency dimension shifts, the screw speed, back pressure, and barrel temperature control gradient are adjusted synchronously according to the corresponding correction amount. When the contribution of the axial flow consistency dimension shifts significantly, it indicates that there is instability or local lag in the screw axial transport process. At this time, the screw speed curve is dynamically adjusted according to the correction amount of the screw extrusion system parameters, and the back pressure control threshold and barrel segment temperature control gradient are corrected synchronously. In specific implementation, the melt viscosity distribution is made more uniform by increasing the speed of the local shear section or adjusting the temperature gradient of the compression section, and the flow stability is maintained by back pressure feedback control, thereby restoring axial flow consistency.

[0061] When the contribution of radial freezing consistency dimension offset exceeds the threshold, the temperature distribution of the cooling medium and the spray flow configuration are adjusted according to the correction amount. When the contribution of radial freezing consistency dimension offset exceeds the set threshold, it is determined that there is unevenness or interlayer freezing difference in the radial curing process of the pipe wall. At this time, the radial cooling medium temperature distribution is adjusted in zones according to the correction amount of the cooling system parameters, and the spray flow configuration is adjusted simultaneously so that the cooling intensity of the inner layer, the middle layer and the outer layer are rematched with their heat conduction requirements. In specific implementation, the radial freezing consistency is improved by increasing the cooling intensity of the inner layer to increase the curing speed or reducing the cooling rate of the outer layer to reduce the stress gradient.

[0062] The correction values ​​of parameters in each dimension are summarized to generate the process input parameters for the next production cycle. After the independent adjustment of each dimension is completed, the correction values ​​of parameters corresponding to the material system, screw extrusion system and cooling system are summarized in a unified manner, and a comprehensive process correction vector is generated by weighted fusion or vector superposition. This correction vector serves as the basis for the process input parameters of the next production cycle, and the original process settings are iteratively updated to form a closed-loop optimization control mechanism, so that subsequent production cycles can automatically compensate for the previous structural offset and realize the adaptive evolution and stable output of process parameters.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for a low-shrinkage, high-voltage-resistant cable protection tube, characterized in that: Includes the following steps: The screw torque fluctuation, barrel segment pressure gradient, melt outlet transient temperature field, and melt resistance change signals are collected synchronously. The above sampled signals are then processed by time reconstruction and phase alignment to form a combination of working condition parameters for characterizing the melt flow state in the transition area from the compression section to the mixing section. Based on the combined operating parameters, according to the structural division of the screw compression section, transition section and mixing section, the changes in melt shear strength in each functional zone are identified by zone, and the flow state difference parameters corresponding to each screw functional zone are output. Based on the influence of the shear strength change between the compression section and the mixing section on the packing migration hysteresis behavior, the flow state difference parameters are corrected by section, and the flow structure response parameters of the screw functional zone are generated. Based on the distribution gradient of the flow structure response parameters of the screw functional areas in the screw axial direction, the screw functional areas are divided into zones for identification, the structural state difference values ​​corresponding to each functional area are obtained, and the process control direction of each functional area of ​​the screw is determined according to the structural state difference values. Then, the temperature control gradient of the barrel segment, the back pressure control threshold and the equivalent shear strength of the mixing elements are adjusted in a coordinated manner. The adjusted process parameters are applied to the extrusion molding process, and the temperature of the cooling medium is controlled in stages along the radial direction after the tube body is formed. The radial temperature drop rate sequence is collected simultaneously. Based on this, a layered mapping analysis is carried out on the tube wall section to analyze the freezing state of each layer. Based on the distribution of the freezing state of the structure, the distribution of the filler orientation structure in the tube wall section is output. Based on the differential analysis of the packing orientation structure distribution in the pipe wall cross section and historical process parameter data, the structural offset is determined, and the material premixing ratio, screw extrusion parameters and cooling control parameters are iteratively corrected accordingly to form the process input parameters for the next production cycle.

2. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to claim 1, characterized in that, The process of generating the operating condition combination parameters to characterize the melt flow state in the transition region from the compression section to the mixing section is as follows: Torque sensing units and pressure sampling units are installed in the feeding section, compression section and mixing section of the screw extruder, respectively, and a transient temperature acquisition array and melt resistance detection module are installed at the barrel outlet. Synchronous calibration is performed on various sensor signals according to the sampling timestamp, and the feeding end is used as the reference time zero point to rearrange the torque fluctuation signal, pressure gradient signal, temperature field change signal and resistance change signal in time sequence. Phase mapping processing is performed on various signals based on the screw rotation cycle, and signal segments corresponding to different functional areas are aligned and spliced ​​together. The aligned multi-source signals are windowed and segmented to extract the signal set of the transition zone between the compression section and the mixing section, and to construct the working condition combination parameters characterizing the changes in the melt flow state.

3. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection pipe according to claim 1, characterized in that, The process of outputting the flow state difference parameters corresponding to each screw functional region is as follows: Based on the geometric division of the screw structure, the working condition combination parameters are mapped to the corresponding spatial intervals of the compression section, transition section, and mixing section; The coupling characteristics of torque fluctuation amplitude and pressure gradient change rate in each functional zone are calculated separately and used as a characterization of shear strength change. By comparing the differences in shear strength between different functional regions, the locations of abrupt changes at the boundaries of the functional regions are extracted. The shear intensity distribution results within each functional zone are normalized, and the difference parameters used to characterize the degree of non-uniformity of the flow state in each screw functional zone are output.

4. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection pipe according to claim 1, characterized in that, The process of generating the flow structure response parameters of the screw functional region is as follows: Identify the shear strength abrupt change intervals between the compression section and the transition section, and between the transition section and the mixing section, and extract the melt resistance change response within the corresponding time window; Based on the time misalignment between the melt resistance change signal and the barrel pressure gradient change signal, the lag time window of the resistance response relative to the shear disturbance is extracted. The slope of the resistance change within the lag time window is integrated and normalized by combining it with the corresponding shear strength change rate to construct a delay factor characterizing the degree of lag in the migration response of the packing under shear drive. The migration lag factor is introduced into the flow state difference parameter of each functional zone to perform weighted correction on the local parameters of the abrupt change interval; The modified functional region parameters are continuously smoothed to generate screw functional region flow structure response parameters that characterize the internal structural response of the melt.

5. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection pipe according to claim 1, characterized in that, The process of obtaining the structural state difference values ​​corresponding to each functional area is as follows: Equally spaced sampling subdivision units are established along the screw axis to reconstruct the flow structure response parameters through spatial interpolation. Calculate the gradient rate of change of response parameters between adjacent subdivided units to form an axially distributed gradient sequence; The boundaries of functional zones are defined based on the continuous rising or falling intervals in the gradient sequence, and the structural boundary positions of each functional zone are determined. Statistical analysis is performed on the dispersion of response parameters in different functional zones, and the structural state difference values ​​corresponding to each functional zone are output.

6. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to claim 1, characterized in that, The process of linking and adjusting the segmented temperature control gradient of the barrel, the back pressure control threshold, and the equivalent shear strength of the mixing elements is as follows: The structural state differences of each functional zone are spatially mapped along the screw axis to obtain the axial distribution results reflecting the degree of deviation of the flow structure, and the structural abrupt change zone and stable zone are identified based on the change characteristics. Within the structural abrupt change region, the structural state difference value is calculated in correspondence with the melt shear response characteristics to generate a shear control weight factor for characterizing the control intensity of each functional region. The segmented temperature control gradient of the barrel is corrected based on the shear control weight factor, and the back pressure control threshold is updated by interval mapping in combination with the back pressure response characteristics of each interval, thus forming the axial shear action distribution. The spatial migration trajectory of the packing in the melt is simultaneously characterized based on the distribution of axial shear action, and the dispersion evolution state of the packing along the screw direction is obtained. For the functional area at the end of the screw, the insufficient amount of packing dispersion is calculated based on the deviation between the dispersion evolution state and the target uniform distribution state. This is then decomposed into two types of control gaps: insufficient shearing action and insufficient residence time. Based on this, the equivalent shearing action intensity of the mixing elements and the axial residence time of the material are adjusted respectively.

7. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection pipe according to claim 1, characterized in that, The process of analyzing the frozen state of each layer of the structure is as follows: The adjusted process parameters are applied to the extrusion molding process. After the tube body is formed, a graded cooling medium control unit is set along the radial direction, and the inner, middle and outer cooling areas are divided according to the tube wall thickness. Different temperature gradients of cooling medium were applied to each cooling zone, and the rate of temperature decrease in each zone over time was recorded. Based on the correspondence between the temperature drop rate in each region and the pipe wall thickness distribution, a mapping relationship between the radial temperature drop rate sequence and the pipe wall structure distribution is constructed. The structural freezing interface is defined based on the inflection point of the temperature drop rate, and the transformation process of each layer of material from a fluid state to a solidified state is obtained.

8. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to claim 1, characterized in that, The process of packing orientation structure distribution within the cross-section of the output pipe wall is as follows: Based on the distribution of the frozen state of the structure, the frozen state of each radial layer is spatially superimposed to form a frozen structure map of the pipe wall section; Based on the differences in freezing rate in different regions of the frozen structure map, the shear residual distribution characteristics of the corresponding regions are extracted, and the orientation of the filler during the melt flow process is determined accordingly. Based on the orientation of the filler, the angular quantification analysis of the orientation changes between each radial layer is performed, the interlayer orientation deviation value is calculated, and a continuously recursive filler orientation gradient distribution sequence is formed. Based on the packing orientation gradient distribution sequence, the radial orientation structure distribution of the packing within the pipe wall cross section is output.

9. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to claim 1, characterized in that, The process of determining the structural offset is as follows: Retrieve screw parameters, temperature control parameters, and cooling parameters corresponding to historical production batches, and extract standard filler orientation structure data for the corresponding batches; The current batch of packing orientation structure distribution is compared with the historical standard packing orientation structure data layer by layer, and corresponding matching is performed according to the radial layer position. Within each radial layer, the orientation angle deviation, interlayer orientation difference, and radial distribution consistency difference are calculated respectively. The above differences are weighted and merged to obtain the structural offset, which is used to characterize the degree of difference between the current structure and the historical standard structure.

10. The manufacturing process of a low-shrinkage, high-voltage-resistant cable protection tube according to claim 1, characterized in that, The process of generating the process input parameters for the next production cycle is as follows: Based on the structural offset, the packing dispersion dimension, axial flow consistency dimension, and radial freezing consistency dimension are decomposed into components to obtain the offset contribution of each dimension. The offset contribution of each dimension is matched with the response coefficients of the material system, screw extrusion system and cooling system to obtain the corresponding parameter correction amount; When the contribution of the filler dispersion dimension offset exceeds the set range, the premixing ratio of elastomer toughening agent and inorganic filler is adjusted according to the parameter correction amount. When the contribution of the axial flow consistency dimension offset shifts, the screw speed, back pressure and barrel temperature control gradient are adjusted synchronously according to the corresponding correction amount. When the radial freezing consistency dimension offset contribution exceeds the threshold, the cooling medium temperature distribution and spray flow configuration are adjusted according to the correction amount. The correction values ​​of parameters in each dimension are summarized to generate the process input parameters for the next production cycle.

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