A real-time monitoring system for cable processing and manufacturing based on the Internet of Things

Abstract

This invention relates to the field of cable measurement technology and discloses a real-time monitoring system for cable processing and manufacturing based on the Internet of Things (IoT). The system includes: real-time acquisition of processed cable data at edge nodes, including hot-end diameter, cold-end diameter, linear velocity, and axial heat flux per unit length; sequential generation of a thermal shrinkage constant and an equivalent specific enthalpy based on the processed cable data; inversion based on the equivalent specific enthalpy to obtain the theoretical thermal shrinkage; acquisition of tension and calculation of mechanical expansion and contraction based on the tension; calculation of abnormal residuals based on the thermal shrinkage constant, theoretical thermal shrinkage, and mechanical expansion and contraction; and obtaining the phase by performing an arcsine transformation on the abnormal residuals and determining the abnormal state of the processed cable based on the phase. This invention can perform predictive adjustments before critical dimension drift exceeds the tolerance, significantly improving the dimensional control accuracy and abnormal response capability of the cable processing process under high-speed speed changes and dynamic conditions.

Description

Technical Field

[0001] This invention relates to the field of cable measurement technology, and more specifically, to a real-time monitoring system for cable processing and manufacturing based on the Internet of Things. Background Technology

[0002] In the manufacturing process of cross-linked polyethylene (XLPE) power cables, the insulation layer is coated onto the outside of the conductor through a hot extrusion process. After extrusion, the cable undergoes a cross-linking reaction through a cross-linking tube and is rapidly cooled in a cooling water bath, ultimately forming stable geometric dimensions. During this process, because XLPE material undergoes significant volume shrinkage when cooled from a high temperature (approximately 250°C) to room temperature, there is a difference in the outer diameter of the insulation layer between the hot and cold ends, known as thermal shrinkage. Generally, to ensure product dimensional compliance, manufacturers deploy high-precision laser diameter gauges online, located near the extruder head (hot end) and at the end of the cooling water bath (cold end), to continuously monitor changes in the outer diameter. Under normal and stable operating conditions, the difference in outer diameter between the hot and cold ends is small and within a controllable range.

[0003] Currently, most cable processing production lines still use fixed-frequency dimensional data acquisition and process control models based on empirical rules. For example, in production management systems (MES) or distributed control systems (DCS), cold-end outer diameter data is typically collected periodically, and deviation tolerances and alarm thresholds are set based on past experience. However, in some dynamic operating scenarios, such as:

[0004] 1. Linear velocity fluctuations caused by reel switching;

[0005] 2. Restart after a short pause;

[0006] 3. Adjustment of traction speed due to product model switching;

[0007] The cold-end dimensional changes collected by the aforementioned system often lag behind changes in the process state itself. This is because the thermal shrinkage of the insulation layer is affected by multiple factors, including: material temperature distribution, cooling efficiency, cross-linking state, and the shortening or lengthening of cooling time caused by changes in traction speed. When the linear velocity changes, the residence time of the material in the cooling water bath will change accordingly, and the cooling rate and degree of cooling will change, directly affecting the final geometric dimensions of the cold end.

[0008] In cable extrusion, dimensional deviations at the cold end are often not due to instability in the hot end extrusion, but rather to dynamic changes in heat conduction and dissipation processes during production line speed variations. This causes the material to enter the next process before cooling is complete. The specific process is as follows:

[0009] 1. Increased linear velocity → shortened residence time in cooling water tank → insufficient cooling → material is pulled before it has stabilized and formed → cold end outer diameter is too large;

[0010] 2. Decreased linear velocity → Increased residence time → Enhanced supercooling contraction → Smaller outer diameter at the cold end;

[0011] 3. If the fixed sampling period fails to cover the key points of speed change, the system will not respond to size abnormalities in a timely manner, and the deviation will accumulate rapidly.

[0012] In summary, if the dimensional control system fails to consider the impact of linear velocity changes on cooling behavior in real time, operators may discover technical problems such as cold end dimensions exceeding the standard during subsequent static inspections, even if the surface data shows that the device is qualified. Summary of the Invention

[0013] This invention provides a real-time monitoring system for cable processing and manufacturing based on the Internet of Things, which solves the technical problems mentioned in the background art.

[0014] This invention provides a real-time monitoring system for cable processing and manufacturing based on the Internet of Things, comprising:

[0015] The data acquisition module is used to collect data on the processed cable in real time at the edge node side, including: hot end diameter, cold end diameter, linear velocity, and axial heat flux per unit length.

[0016] The parameter processing module is used to sequentially generate the thermal shrinkage constant and equivalent specific enthalpy based on the processed cable data;

[0017] The first analytical module is used to perform inversion based on the equivalent specific enthalpy to obtain the theoretical thermal shrinkage.

[0018] The second analysis module is used to obtain the tension and calculate the mechanical expansion and contraction based on the tension;

[0019] The analytical synthesis module is used to calculate abnormal residuals based on the thermal shrinkage constant, theoretical thermal shrinkage, and mechanical expansion and contraction.

[0020] The abnormality locking module is used to perform an arcsine transformation on the abnormal residual to obtain the phase, and to determine the abnormal state of the processed cable based on the phase.

[0021] The parameter processing module, the first parsing module, the second parsing module, the parsing synthesis module, and the anomaly locking module all run on the cloud platform side, which is used for centralized processing of cable processing data.

[0022] Furthermore, the thermal shrinkage constant is generated based on the processed cable data, including:

[0023] The diameter difference is obtained by subtracting the diameter of the hot end from the diameter of the cold end.

[0024] Determine the square root of the linear velocity, and apply a first-order low-pass filter to the square root of the linear velocity to obtain the thermal shrinkage weight.

[0025] The product of the diameter difference and the thermal shrinkage weight is used as the thermal shrinkage constant.

[0026] Furthermore, an equivalent specific enthalpy is generated based on the processed cable data, including:

[0027] Obtain the material density and specific heat of the cable;

[0028] Based on the material density and specific heat of the cable, the cable is marked as either high-crystallinity cross-linked polyethylene or low-crystallinity cross-linked polyethylene, and the product of the material density and specific heat is used as the initial specific enthalpy of the cable.

[0029] The window average values ​​of thermal contraction constant and axial heat flux per unit length within a preset time period are obtained respectively.

[0030] The desired thermal shrinkage constants of highly crystalline cross-linked polyethylene and low-crystalline cross-linked polyethylene were determined respectively.

[0031] The ratio of the window average value of the heat shrinkage constant to the corresponding heat shrinkage constant of the cable is used as the deviation.

[0032] If the deviation is less than or equal to the preset deviation threshold, the initial specific enthalpy is weighted based on the window average value of heat flow per unit length along the axial direction to obtain the equivalent specific enthalpy.

[0033] If the deviation exceeds the preset deviation threshold, a specific enthalpy weight is generated based on the deviation, and the product of the specific enthalpy weight, the window average value of the heat flux per unit length along the axis, and the initial specific enthalpy is used as the equivalent specific enthalpy.

[0034] Furthermore, based on the equivalent specific enthalpy, the theoretical thermal shrinkage is obtained through inversion, including:

[0035] The hot and cold ends of the cable are designated as cooling sections, and the length of the cooling sections is determined.

[0036] The ratio of cooling section length to linear velocity is used as the cooling time. ;

[0037] According to the preset calibration coefficient The theoretical thermal shrinkage is calculated using the diffusion time scale, including:

[0038]

[0039] in, Indicates the theoretical thermal shrinkage. Indicates equivalent specific enthalpy. Indicates the diffusion time scale, .

[0040] Furthermore, based on the obtained tension, and calculating the mechanical expansion and contraction amount according to the tension, including:

[0041] Determine the elastic expansion coefficient of the cable;

[0042] The product of the elastic coefficient and the tension is taken as the mechanical expansion amount.

[0043] Furthermore, based on the thermal shrinkage constant, theoretical thermal shrinkage, and mechanical expansion / contraction, abnormal residuals are calculated, including:

[0044] The sum of the theoretical thermal shrinkage and the mechanical expansion and contraction is taken as the total expansion and contraction.

[0045] The difference between the thermal shrinkage constant and the total expansion / contraction is taken as the abnormal residual.

[0046] Furthermore, the abnormal residuals are subjected to an arcsine transform to obtain the phase, and the abnormal state of the processed cable is determined based on the phase, including:

[0047] The phase is obtained by performing an arcsine transform on the abnormal residual;

[0048] The phase change rate is obtained by differentiating the phase over time.

[0049] The absolute value of the phase is compared with a preset amplitude threshold, and the phase change rate is simultaneously compared with a preset slope threshold. An abnormal state is output, which includes: locked state, search or unlocked state.

[0050] Furthermore, cable processing compensation procedures are performed based on the abnormal condition of the processed cable, including:

[0051] If the abnormal state is locked or searching, the linear velocity, cooling water temperature, nitrogen pressure and tension will be adjusted synchronously according to the preset weights until the abnormal state is locked.

[0052] The beneficial effects of this invention are as follows: By introducing an IoT-based data acquisition and cloud processing architecture, multi-source real-time parameters such as hot-end diameter, cold-end diameter, linear velocity, axial heat flux per unit length, and tension during cable processing are comprehensively calculated. A dynamic dimensional evolution model is constructed with thermal shrinkage constant → equivalent specific enthalpy → theoretical thermal shrinkage → mechanical expansion and contraction as the support chain. With abnormal residuals as the core, a phase judgment mechanism is constructed through an arcsine function to achieve millisecond-level early identification and intervention control of fluctuations in the outer diameter of the cold end of the cable. This enables the monitoring system to not only respond to thermal, force, and velocity process disturbances, but also to complete predictive adjustments before the drift of critical dimensions exceeds the tolerance. This significantly improves the dimensional control accuracy and abnormal response capability of the cable processing process under high-speed speed change and dynamic working conditions. Attached Figure Description

[0053] Figure 1 This is a block diagram of the present invention. Detailed Implementation

[0054] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0055] like Figure 1 As shown, an IoT-based real-time monitoring system for cable processing and manufacturing includes:

[0056] The data acquisition module is used to collect data on the processed cable in real time at the edge node side, including: hot end diameter, cold end diameter, linear velocity, and axial heat flux per unit length.

[0057] The parameter processing module is used to sequentially generate the thermal shrinkage constant and equivalent specific enthalpy based on the processed cable data;

[0058] The first analytical module is used to perform inversion based on the equivalent specific enthalpy to obtain the theoretical thermal shrinkage.

[0059] The second analysis module is used to obtain the tension and calculate the mechanical expansion and contraction based on the tension;

[0060] The analytical synthesis module is used to calculate abnormal residuals based on the thermal shrinkage constant, theoretical thermal shrinkage, and mechanical expansion and contraction.

[0061] The abnormality locking module is used to perform an arcsine transformation on the abnormal residual to obtain the phase, and to determine the abnormal state of the processed cable based on the phase.

[0062] The parameter processing module, the first parsing module, the second parsing module, the parsing synthesis module, and the anomaly locking module all run on the cloud platform side, which is used for centralized processing of cable processing data.

[0063] In detail, the hot end diameter refers to the outer diameter of the cable immediately after it is extruded from the extruder head, when it is at a high temperature (approximately 250 degrees Celsius). At this time, the cable insulation layer has not yet been sufficiently cooled and is in a thermally unstable state. The hot end diameter is measured in real time by a laser outer diameter gauge① deployed near the extruder head.

[0064] In detail, the cold end diameter refers to the outer diameter of the cable after it has been cooled in the cooling water tank and is at room temperature. At this point, the cable insulation layer has largely shrunk, and the dimensions are relatively stable. The cold end diameter is measured in real time by a laser outer diameter gauge ② deployed at the end of the cooling water tank.

[0065] In detail, linear velocity refers to the speed at which the cable moves as it is pulled by the traction equipment during processing. It directly affects the cable's residence time in the cooling water tank, thus influencing the cooling effect and the final dimensions. The linear velocity is acquired in real time by an encoder, which is linked to the traction equipment to record the cable's movement speed in real time.

[0066] In detail, axial heat flux per unit length refers to the heat flow rate per unit length along the axial direction of the cable. It reflects the heat transfer intensity of the cable during processing and is closely related to the material cooling rate. Axial heat flux per unit length is measured in real time by an axial heat flux density meter.

[0067] In one embodiment of the present invention, generating a thermal shrinkage constant based on processed cable data includes:

[0068] The diameter difference is obtained by subtracting the diameter of the hot end from the diameter of the cold end.

[0069] Determine the square root of the linear velocity, and apply a first-order low-pass filter to the square root of the linear velocity to obtain the thermal shrinkage weight.

[0070] The product of the diameter difference and the thermal shrinkage weight is used as the thermal shrinkage constant.

[0071] In detail, the hot end diameter is the outer diameter of the cable at high temperature when it is first extruded, and the cold end diameter is the outer diameter of the cable at room temperature after cooling. The difference in diameter directly reflects the original dimensional change of the cable due to thermal shrinkage during the cooling process, and is the basic physical quantity for calculating the thermal shrinkage constant.

[0072] In detail, linear velocity is the traction speed of the cable during processing, and its magnitude directly affects the residence time of the cable in the cooling water tank. Higher linear velocity results in shorter residence time, less sufficient cooling, and less complete heat shrinkage; lower linear velocity results in longer residence time and more complete heat shrinkage. Since the amount of heat shrinkage is related to the square root of the cooling time, the square root of the linear velocity is used as a basic parameter to reflect the influence of linear velocity on heat shrinkage. A first-order low-pass filter is applied to the square root of the linear velocity to eliminate interference from instantaneous fluctuations in linear velocity. In actual processing, linear velocity may fluctuate at high frequencies due to equipment vibration, traction system fine-tuning, etc. These fluctuations are not stable process changes, and directly using them for calculations would distort the heat shrinkage weight. The first-order low-pass filter can filter out high-frequency noise, retain the trend of linear velocity changes, and make the heat shrinkage weight more stably reflect the actual influence of linear velocity on heat shrinkage. The heat shrinkage weight obtained after filtering is essentially a normalized coefficient of the influence of linear velocity on heat shrinkage.

[0073] In detail, the diameter difference is multiplied by the heat shrinkage weight to obtain the heat shrinkage constant. This heat shrinkage weight is then used to correct for the linear velocity-related effects, transforming the diameter difference from a simple dimensional change into a quantitative indicator that truly reflects the material's heat shrinkage characteristics.

[0074] In one embodiment of the present invention, generating an equivalent enthalpy based on processed cable data includes:

[0075] Obtain the material density and specific heat of the cable;

[0076] Based on the material density and specific heat of the cable, the cable is marked as either high-crystallinity cross-linked polyethylene or low-crystallinity cross-linked polyethylene, and the product of the material density and specific heat is used as the initial specific enthalpy of the cable.

[0077] The window average values ​​of thermal contraction constant and axial heat flux per unit length within a preset time period are obtained respectively.

[0078] The desired thermal shrinkage constants of highly crystalline cross-linked polyethylene and low-crystalline cross-linked polyethylene were determined respectively.

[0079] The ratio of the window average value of the heat shrinkage constant to the corresponding heat shrinkage constant of the cable is used as the deviation.

[0080] If the deviation is less than or equal to the preset deviation threshold, the initial specific enthalpy is weighted based on the window average value of heat flow per unit length along the axial direction to obtain the equivalent specific enthalpy.

[0081] If the deviation exceeds the preset deviation threshold, a specific enthalpy weight is generated based on the deviation, and the product of the specific enthalpy weight, the window average value of the heat flux per unit length along the axis, and the initial specific enthalpy is used as the equivalent specific enthalpy.

[0082] In detail, material density is the mass of a unit volume of material, reflecting how compact the material is; specific heat is the amount of heat required to raise the temperature of a unit mass of material by 1 degree Celsius, reflecting the material's ability to store heat. Both are inherent properties of materials, directly determining their thermal conductivity and contraction characteristics.

[0083] In detail, based on the numerical range of material density and specific heat, the current batch of cables is marked as either high-crystallinity cross-linked polyethylene (PCPE) or low-crystallinity PCPE. The different molecular densities of high-crystallinity and low-crystallinity PCPE result in significant differences in their heat shrinkage characteristics. This classification ensures that subsequent processing uses matching baseline parameters, avoiding cross-material errors. Specifically:

[0084] The system's material parameter library pre-stores typical numerical ranges for the material density and specific heat of high-crystallinity XLPE and low-crystallinity XLPE (this range is calibrated based on experimental data of the crystallinity of cross-linked polyethylene materials, reflecting the influence of the degree of molecular packing on thermal properties under different crystallinities):

[0085] Highly crystalline XLPE: The molecules are more tightly packed, resulting in a relatively high density and a relatively low specific heat. For example, the preset density range is 930 to 950 kg / m³, and the specific heat range is 1.8 to 2.0 kJ / (kg・K).

[0086] Low-crystallinity XLPE: The molecular arrangement is relatively loose, the density is relatively low, and the specific heat is relatively high. For example, the preset density range is 910 to 930 kg / m³, and the specific heat range is 2.0 to 2.2 kJ / (kg・K).

[0087] When processing the current batch of cables, the system performs the following operations:

[0088] Retrieve the actual material density and specific heat value of the current batch of cable insulation material from the material parameter library; compare the actual values ​​with the preset threshold ranges for high-crystallinity and low-crystallinity XLPE:

[0089] If both the material density and specific heat fall within the preset range for high-crystallinity XLPE, then the current batch will be marked as high-crystallinity cross-linked polyethylene.

[0090] If both the material density and specific heat fall within the preset range for low-crystallinity XLPE, the current batch will be marked as low-crystallinity crosslinked polyethylene.

[0091] In detail, the initial specific enthalpy is obtained by calculating the product of the material density and the material specific heat, so as to comprehensively reflect the heat storage capacity per unit volume of the material.

[0092] In detail, the window average values ​​for the axial heat flux per unit length and thermal contraction constant acquired in real time are calculated over a preset time period. The window average value, calculated by averaging multiple consecutive frames of data, eliminates instantaneous fluctuations and makes the data more stably reflect the overall trend.

[0093] In detail, to quantify the difference between the actual process state and the ideal state, it is necessary to first determine the expected heat shrinkage constant: for high-crystallinity and low-crystallinity cross-linked polyethylene, standard values ​​of heat shrinkage constant under stable operating conditions are set respectively. The standard values ​​of heat shrinkage constant are obtained by statistical analysis of historical qualified data.

[0094] In detail, the deviation is calculated as the ratio of the windowed average value of the thermal shrinkage constant to the expected thermal shrinkage constant of the corresponding material. The deviation directly reflects the degree of deviation between the current thermal shrinkage state and the standard state.

[0095] In detail, the final calculation of the equivalent specific enthalpy requires different weighting strategies depending on the degree of deviation, so that the results more accurately match the actual thermal state:

[0096] If the deviation is less than or equal to the preset deviation threshold, it means that the process condition is close to ideal. At this time, the initial specific enthalpy is slightly weighted based on the window average value of the heat flow per unit length along the axis (weight close to 1), and the initial specific enthalpy is finely adjusted to match the real-time heat flow changes.

[0097] If the deviation is greater than the preset deviation threshold, it indicates that the process state deviates significantly from the ideal. At this time, a specific enthalpy weight is generated based on the deviation (the specific enthalpy weight is the sum of the deviation and 1), and the specific enthalpy weight, the window average value of the heat flow per unit length along the axis, and the initial specific enthalpy are multiplied together. By increasing the weight adjustment, the equivalent specific enthalpy more significantly reflects the combined effect of the actual heat flow and the process deviation.

[0098] In one embodiment of the present invention, the theoretical thermal shrinkage is obtained by inversion based on the equivalent specific enthalpy, including:

[0099] The hot and cold ends of the cable are designated as cooling sections, and the length of the cooling sections is determined.

[0100] The ratio of cooling section length to linear velocity is used as the cooling time. ;

[0101] According to the preset calibration coefficient The theoretical thermal shrinkage is calculated using the diffusion time scale, including:

[0102]

[0103] in, Indicates the theoretical thermal shrinkage. Indicates equivalent specific enthalpy. Indicates the diffusion time scale, .

[0104] In detail, the cooling section refers to the physical segment of the cable from the hot end to the cold end. The hot end is the high-temperature section of the cable immediately after it is extruded from the extruder head, at which point the insulation layer is in an uncooled, hot state. The cold end is the section of the cable at room temperature after passing through the cooling water tank, where the insulation layer has completed its main shrinkage. The length of the cooling section, i.e., the actual distance between the hot and cold ends, is a fixed parameter determined by the structure of the production equipment, reflecting the total path length that the cable must traverse during the cooling process.

[0105] In detail, cooling time is the total time it takes for the cable to pass through the cooling section. Based on the fundamental principles of kinematics: the time required for a cable to continuously move at linear velocity through a fixed-length cooling section is equal to the ratio of the cooling section length to the linear velocity. Specifically, linear velocity is the speed at which the cable is pulled by the traction equipment, and the length of the cooling section is a fixed equipment parameter. The cooling time obtained by dividing the two directly reflects the actual residence time of the cable within the cooling section. That is, the longer the residence time, the more sufficient the heat exchange between the insulation layer and the cooling medium, and theoretically, the more significant the thermal contraction.

[0106] In detail, the diffusion time scale is a correction parameter for the cooling time, calculated as π multiplied by the cooling time and then divided by 4. This simplifies the mathematical expression of the thermal diffusion process: the thermal shrinkage of cable insulation material (cross-linked polyethylene) is essentially a volume change driven by thermal diffusion, a process involving complex calculations of heat conduction series. By introducing the constant π / 4, the main modes of thermal diffusion can be approximated as a single exponential term, significantly reducing the complexity of real-time calculations while retaining the core law of thermal diffusion changing over time.

[0107] In detail, theoretical thermal shrinkage refers to the amount of shrinkage of the cable insulation layer due to cooling under ideal conditions (no mechanical interference, sufficient and stable heat conduction). The calculation formula is that theoretical thermal shrinkage is equal to the preset calibration coefficient multiplied by the equivalent enthalpy and then multiplied by the square root of the diffusion time scale.

[0108] The preset calibration coefficient is a constant calibrated through offline experiments. It is used to match the thermal shrinkage characteristics of cable materials (such as cross-linked polyethylene) with the actual operating conditions of production equipment, ensuring that theoretical calculations are consistent with actual shrinkage patterns. The equivalent specific enthalpy is a comprehensive parameter reflecting the thermal properties of the material. It integrates information such as material density, specific heat, and actual heat flow, and is directly related to the heat input state of the insulation layer. The square root term of the diffusion time scale reflects the basic law of the thermal diffusion process. The amount of thermal shrinkage is proportional to the square root of time, which is consistent with the characteristic that the diffusion depth is related to the square root of time in the physical model of heat conduction.

[0109] In one embodiment of the present invention, the process of obtaining tension and calculating mechanical expansion / contraction based on tension includes:

[0110] Determine the elastic expansion coefficient of the cable;

[0111] The product of the elastic coefficient and the tension is taken as the mechanical expansion amount.

[0112] In detail, the elastic expansion coefficient is a key parameter characterizing the mechanical expansion and contraction properties of a cable under tension. It represents the change in the cable's outer diameter under unit tension, measured in millimeters per Newton (mm / N). The value of this coefficient is directly related to the specific characteristics of the cable, including the conductor cross-sectional size, the elastic modulus of the insulation material, and the product model. For example, larger cross-sectional cables are more rigid, and their elastic expansion coefficient is usually smaller than that of smaller cross-sectional cables. Differences in the elasticity of different insulation materials (such as high-crystallinity cross-linked polyethylene and low-crystallinity cross-linked polyethylene) will also lead to different coefficient values. Determining this coefficient requires consideration of the actual production scenario and is generally achieved through offline calibration experiments: multiple tensile tests are performed on the same type of cable within a specific tension range, the relationship between tension changes and corresponding outer diameter changes is recorded, and the elastic expansion coefficient of the cable model is calculated through linear fitting and stored in the system parameter library for use in actual production.

[0113] In detail, after obtaining the real-time tension and the corresponding elastic expansion coefficient, the mechanical expansion amount is obtained by multiplying the two. Based on the application of Hooke's Law in mechanics of materials within a small deformation range, when tension acts on a cable, the resulting mechanical expansion amount is linearly related to the magnitude of the tension; the proportionality coefficient is the elastic expansion coefficient. The physical meaning of mechanical expansion amount is the change in the cable's outer diameter caused solely by tension. It is independent of other factors such as thermal shrinkage and specifically reflects the influence of mechanical force on dimensions. For example, if the elastic expansion coefficient is 0.002 mm / Newton and the real-time tension is 500 Newtons, then the mechanical expansion amount is 0.002 multiplied by 500 equals 1 mm, meaning that the tension causes a 1 mm mechanical change in the cable's outer diameter.

[0114] In one embodiment of the present invention, the abnormal residual is calculated based on the thermal shrinkage constant, the theoretical thermal shrinkage, and the mechanical expansion and contraction, including:

[0115] The sum of the theoretical thermal shrinkage and the mechanical expansion and contraction is taken as the total expansion and contraction.

[0116] The difference between the thermal shrinkage constant and the total expansion / contraction is taken as the abnormal residual.

[0117] In detail, theoretical thermal shrinkage is a value obtained through inversion using a thermal diffusion model. It represents the amount of thermal shrinkage determined solely by the thermal properties of the material under ideal cooling conditions, and is a theoretical expectation of the normal thermal shrinkage process. Mechanical expansion and contraction is the dimensional change calculated based on tension, reflecting the elastic expansion and contraction of the cable caused by mechanical traction force, and belongs to the dimensional deviation under normal mechanical action.

[0118] In detail, the calculation of abnormal residuals involves two steps. The first step is to calculate the total expansion and contraction, which is to add the theoretical thermal shrinkage and mechanical expansion and contraction. This sum represents the total dimensional change that the cable should have under the condition of no abnormal factors. The theoretical thermal shrinkage reflects the influence of normal thermal processes, while the mechanical expansion and contraction reflects the influence of normal mechanical processes; together, they constitute the dimensional change benchmark under ideal conditions. The second step is to calculate the abnormal residuals, which is to subtract the total expansion and contraction from the thermal shrinkage constant. The thermal shrinkage constant includes dimensional changes caused by all factors (including normal and abnormal factors) in actual processing, while the total expansion and contraction only includes the influence of normal factors. Therefore, the difference between the two is the abnormal residual, which reflects dimensional deviations caused by abnormal factors that cannot be explained by thermal or mechanical models.

[0119] In one embodiment of the present invention, the abnormal residual is subjected to an arcsine transform to obtain the phase, and the abnormal state of the processed cable is determined based on the phase, including:

[0120] The phase is obtained by performing an arcsine transform on the abnormal residual;

[0121] The phase change rate is obtained by differentiating the phase over time.

[0122] The absolute value of the phase is compared with a preset amplitude threshold, and the phase change rate is simultaneously compared with a preset slope threshold. An abnormal state is output, which includes: locked state, search or unlocked state.

[0123] It should be noted that abnormal residuals are dimensional offsets reflecting only abnormal factors after stripping away normal thermal shrinkage and mechanical expansion. An arcsine transform is applied to obtain the phase, thus mapping the linear residual data to an angular quantity with periodic characteristics. Specifically, the numerical range of abnormal residuals is limited by the upper limit of the residuals; after normalization, it can be mapped to the interval -1 to 1. The arcsine function can unambiguously convert the values ​​in this interval into phase angles of -90 degrees to 90 degrees. On the one hand, by transforming the phase angle, residuals of different orders of magnitude are unified to the angular dimension, eliminating the influence of differences in the absolute value of residuals under different cable specifications. On the other hand, changes in the phase angle can directly reflect the synchronicity of the anomaly. If the phase is stable within a small angle range, it indicates that the anomaly is under control; if the phase increases rapidly, it indicates that the anomaly is intensifying.

[0124] The phase change rate is obtained by differentiating the phase over time, and it is used to quantify the dynamic development trend of an anomaly. The magnitude of the phase change rate directly reflects the rate of deterioration of the anomaly: when the phase change rate is small, it indicates that the anomaly is changing slowly, and the system has sufficient time to adjust; when the phase change rate increases sharply, it indicates that the anomaly is rapidly intensifying, and immediate intervention is required to avoid dimensional deviations. For example, if it takes 10 seconds for the phase to increase from 1 degree to 5 degrees, the phase change rate is 0.4 degrees / second, indicating that the anomaly is developing slowly; if the same phase change takes only 2 seconds, the phase change rate is 2 degrees / second, indicating that the anomaly is deteriorating rapidly.

[0125] By comparing the absolute value of the phase with a preset amplitude threshold and the rate of phase change with a preset slope threshold, the abnormal state of the processed cable can be comprehensively determined. The specific logic is as follows:

[0126] Locked-in state: When the absolute value of the phase is less than or equal to the amplitude threshold and the rate of phase change is less than or equal to the slope threshold, it is determined to be in a locked-in state. At this time, the abnormal residual is in a very small range and changes slowly, indicating that the cable processing process is stable and no additional intervention is required.

[0127] Search status: When the absolute value of the phase exceeds the amplitude threshold but the rate of phase change is still less than or equal to the slope threshold, or when the rate of phase change exceeds the slope threshold but the absolute value of the phase is less than or equal to the amplitude threshold, the search status is determined. At this time, the anomaly has appeared but has not yet deteriorated rapidly.

[0128] Unlocked state: When the absolute value of the phase exceeds the amplitude threshold and the rate of phase change simultaneously exceeds the slope threshold, the state is determined to be unlocked. At this point, the anomaly has become severe and is rapidly deteriorating.

[0129] In one embodiment of the present invention, cable processing compensation processing is performed based on the abnormal state of the processed cable, including:

[0130] If the abnormal state is locked or searching, the linear velocity, cooling water temperature, nitrogen pressure and tension will be adjusted synchronously according to the preset weights until the abnormal state is locked.

[0131] In detail, the compensation process is achieved by synchronously adjusting four key parameters, each of which plays a role in addressing different causes of the anomaly:

[0132] Linear velocity directly affects the residence time of the cable in the cooling section. Increasing the linear velocity shortens the cooling time, potentially leading to insufficient cooling; decreasing the linear velocity prolongs the cooling time, potentially causing overcooling shrinkage. Adjusting the linear velocity can quickly change the cooling efficiency to match the material's thermal shrinkage requirements.

[0133] Cooling water temperature determines the cooling intensity. Lowering the water temperature enhances heat dissipation and accelerates material setting; raising the water temperature weakens heat dissipation and slows down shrinkage. By adjusting the water temperature, the heat exchange rate can be precisely controlled, correcting for thermal shrinkage deviations.

[0134] Nitrogen pressure affects the degree of cross-linking reaction and material density. Excessive nitrogen pressure may lead to a higher material density and less shrinkage; conversely, insufficient nitrogen pressure may result in a lower material density and increased shrinkage. Adjusting the nitrogen pressure can correct the influence of the material's structural properties on shrinkage.

[0135] Tension affects cable dimensions through mechanical force. Increased tension causes the cable to stretch and deform, reducing its outer diameter; decreased tension may cause the cable to loosen, resulting in an excessively large outer diameter. Adjusting the tension can counteract dimensional deviations caused by mechanical factors.

[0136] Synchronous adjustment does not involve adjusting all four parameters with equal force, but rather allocating adjustment amplitudes according to preset weights. The weights are set based on the sensitivity of each parameter to anomalies: for example, linear velocity has the most direct impact on cooling time, and its weight may be higher in high-speed gear-changing scenarios; coolant temperature provides more precise correction for thermal contraction, and its weight may be greater during steady-state fine-tuning. Preset weights ensure that adjustment resources are concentrated on the parameters most effective for the current anomaly, improving correction efficiency and avoiding new disturbances caused by ineffective adjustments.

[0137] It should be noted that highly crystalline cross-linked polyethylene has a density in the range of 930 to 950 kg / m³, and a specific heat in the range of 1.8 to 2.0 kJ / kg / Kelvin. Low crystalline cross-linked polyethylene has a density in the range of 910 to 930 kg / m³, and a specific heat in the range of 2.0 to 2.2 kJ / kg / Kelvin.

[0138] It should be noted that the deviation thresholds include: a tolerance of up to 12% for highly crystalline materials and up to 15% for low-crystalline materials. These deviation thresholds are derived from three times the statistical standard deviation of the steady-state sample of good products, with an additional 1% quantization margin.

[0139] It should be noted that when the deviation is still within the allowable range, a small correction is made based on the initial specific enthalpy according to the proportion of the relative change in heat flux, and the correction coefficient is preferably 0.1 to 0.3. When the deviation exceeds the allowable range, the equivalent specific enthalpy is applied using a weighted multiplication method that amplifies with the deviation, and the weight gain is preferably 0.3 to 0.8.

[0140] It should be noted that the upper limit of residual normalization is calculated using a statistical method: the steady-state data of good products over the past 24 hours is selected, and the value at the 99th percentile of the absolute value of abnormal residuals is used as the basis. Then, a safety factor of about 15% is applied to obtain the upper limit of residual normalization.

[0141] It should be noted that the phase amplitude threshold is based on the value at the 95th percentile of the abnormal residual, multiplied by a 20% amplification factor, and then converted to phase space to obtain the amplitude threshold.

[0142] It should be noted that the phase slope threshold uses a 3-degree phase change as the amplitude, divided by the observation window length of 1 to 2 seconds to obtain the threshold. The phase change rate is calculated as the ratio of the difference between adjacent sampled phases to the sampling period.

[0143] It should be noted that the calibration process for the preset calibration coefficients is as follows:

[0144] Data acquisition: Select no fewer than fifty samples, covering steady-state and variable-speed operating conditions, and record equivalent specific enthalpy, diffusion time scale, thermal contraction constant, and tension.

[0145] Fitting objective: Using the least squares principle, minimize the sum of squares of the differences between the thermal shrinkage constant and the theoretical quantity composed of the equivalent specific enthalpy, the square root of the diffusion time scale, and the mechanical expansion term, thereby obtaining the preset calibration coefficient.

[0146] It should be noted that the process for determining the elastic coefficient of stretching is as follows:

[0147] Test conditions: constant ambient temperature of 25 degrees Celsius; three tension levels were applied to the target traction section, including 300 Newtons, 500 Newtons and 800 Newtons; the change in outer diameter was measured simultaneously.

[0148] The linearity test involves fitting the outer diameter change to the tension linearly to obtain the elastic expansion coefficient.

[0149] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A real-time monitoring system for cable processing and manufacturing based on the Internet of Things, characterized in that, include: The data acquisition module is used to collect data on the processed cable in real time at the edge node side, including: hot end diameter, cold end diameter, linear velocity, and axial heat flux per unit length. The parameter processing module is used to sequentially generate the thermal shrinkage constant and equivalent specific enthalpy based on the processed cable data; The diameter difference is obtained by subtracting the diameter of the hot end from the diameter of the cold end. Determine the square root of the linear velocity, and apply a first-order low-pass filter to the square root of the linear velocity to obtain the thermal shrinkage weight. The product of the diameter difference and the thermal shrinkage weight is taken as the thermal shrinkage constant; Obtain the material density and specific heat of the cable; Based on the material density and specific heat of the cable, the cable is marked as either high-crystallinity cross-linked polyethylene or low-crystallinity cross-linked polyethylene, and the product of the material density and specific heat is used as the initial specific enthalpy of the cable. The window average values ​​of thermal contraction constant and axial heat flux per unit length within a preset time period are obtained respectively. The desired thermal shrinkage constants of highly crystalline cross-linked polyethylene and low-crystalline cross-linked polyethylene were determined respectively. The ratio of the window average value of the heat shrinkage constant to the corresponding heat shrinkage constant of the cable is used as the deviation. If the deviation is less than or equal to the preset deviation threshold, the initial specific enthalpy is weighted based on the window average value of heat flow per unit length along the axial direction to obtain the equivalent specific enthalpy. If the deviation is greater than the preset deviation threshold, the specific enthalpy weight is generated based on the deviation, and the product of the specific enthalpy weight, the window average value of the heat flux per unit length along the axis, and the initial specific enthalpy is used as the equivalent specific enthalpy. The first analytical module is used to perform inversion based on the equivalent specific enthalpy to obtain the theoretical thermal shrinkage. The hot and cold ends of the cable are designated as cooling sections, and the length of the cooling sections is determined. The ratio of cooling section length to linear velocity is used as the cooling time. ; According to the preset calibration coefficient Theoretical thermal shrinkage is calculated using the diffusion time scale; The preset calibration coefficient is a constant calibrated through offline experiments and is used to match the thermal shrinkage characteristics of cable materials; The formula for calculating theoretical thermal shrinkage is as follows: ； in, Indicates the theoretical thermal shrinkage. Indicates equivalent specific enthalpy. Indicates the diffusion time scale, ; The second analysis module is used to obtain the tension and calculate the mechanical expansion and contraction based on the tension; Determine the elastic expansion coefficient of the cable; The product of the elastic coefficient and the tension is taken as the mechanical expansion / contraction amount; The analytical synthesis module is used to calculate abnormal residuals based on the thermal shrinkage constant, theoretical thermal shrinkage, and mechanical expansion and contraction. The sum of the theoretical thermal shrinkage and the mechanical expansion and contraction is taken as the total expansion and contraction. The difference between the thermal shrinkage constant and the total expansion / contraction is taken as the abnormal residual; The abnormal locking module is used to perform an arcsine transformation on the abnormal residual to obtain the phase, and to determine the abnormal state of the processed cable based on the phase. The parameter processing module, the first parsing module, the second parsing module, the parsing synthesis module, and the anomaly locking module all run on the cloud platform side, which is used for centralized processing of cable processing data.

2. The real-time monitoring system for cable processing and manufacturing based on the Internet of Things according to claim 1, characterized in that, The abnormal residual is subjected to an arcsine transform to obtain the phase, and the abnormal state of the processed cable is determined based on the phase, including: The phase is obtained by performing an arcsine transform on the abnormal residual; The phase change rate is obtained by differentiating the phase over time. The absolute value of the phase is compared with a preset amplitude threshold, and the phase change rate is simultaneously compared with a preset slope threshold. An abnormal state is output, which includes: locked state, search or unlocked state.

3. The real-time monitoring system for cable processing and manufacturing based on the Internet of Things according to claim 2, characterized in that, Perform cable processing compensation procedures based on the abnormal condition of the processed cable, including: If the abnormal state is unlocked or searched, the linear velocity, cooling water temperature, nitrogen pressure and tension will be adjusted synchronously according to the preset weights until the abnormal state is locked.

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