Cable extrusion process energy saving control system based on edge computing

Abstract

The present application relates to the technical field of cable manufacturing and industrial automation control, in particular to a cable extrusion process energy-saving control system based on edge computing, comprising: a multi-dimensional data acquisition module, which acquires the running state data of the extruder system in real time; an edge rheological solution module, which solves the apparent viscosity value of the current material in real time and constructs a virtual rheological state representation; a thermal engine efficiency decoupling module, which generates an energy efficiency comparison coefficient; a double-loop predictive control module, which is used for executing a dynamic set point drift strategy according to the energy efficiency comparison coefficient, and when the energy efficiency comparison coefficient indicates that the shear heat generation efficiency is superior to the electric heating efficiency, actively reducing the temperature set value of the temperature control loop to maintain the apparent viscosity value within the preset melting quality constraint range; the present application eliminates the energy consumption among the actuators and greatly improves the thermodynamic stability of the system.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing and industrial automation control technology, specifically to an energy-saving control system for cable extrusion processes based on edge computing. Background Technology

[0002] In current cable extrusion production processes, extruder control systems primarily rely on fieldbus data collection of basic operating data such as temperature, pressure, and current, and maintain equipment operation based on preset process card parameters. To ensure material plasticization quality, existing solutions generally employ an independent PID single-loop control architecture. This involves adjusting the start and stop of the heater and fan via a temperature control loop to maintain a constant barrel temperature, while simultaneously adjusting the screw speed independently via a speed control loop. Although this approach provides some process maintenance capability under steady-state conditions, it severs the physical conversion between mechanical shear energy and electrothermal energy, often treating the endogenous shear heat generated by screw rotation as... Temperature disturbances frequently trigger fan cooling, leading to an energy conflict between heating and cooling actions. Furthermore, due to the lack of online rheological detection hardware and the inherently large hysteresis of the equipment, existing control logic struggles to perceive the true rheological state of materials in real time. This prevents dynamic adjustment of the mechanical and thermal energy input ratios while maintaining viscosity consistency, resulting in significant production process response delays, low overall energy efficiency, and difficulty in achieving refined closed-loop control. Therefore, how to construct a rheological state characterization based on real-time operational data and achieve coordinated decoupled control of thermal and mechanical energy to improve system energy efficiency and stability has become a pressing technical problem. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an energy-saving control system for cable extrusion processes based on edge computing. Specifically, the technical solution of this invention includes:

[0004] The multi-dimensional data acquisition module is used to acquire the operating status data of the extruder system in real time via fieldbus. The operating status data includes the motor current value of the drive motor, the screw speed value, the current temperature value of each temperature zone of the barrel, and the die head pressure value.

[0005] The edge rheology calculation module is used to calculate the apparent viscosity of the current material in real time based on the motor current value and the screw speed value using a preset non-Newtonian fluid rheology model, and to construct a virtual rheological state characterization.

[0006] The thermal engine energy efficiency decoupling module is used to calculate the electric heating energy efficiency index and the shear heat generation energy efficiency index under the current operating conditions based on the operating status data, and to calculate the ratio of the shear heat generation energy efficiency index to the electric heating energy efficiency index to generate an energy efficiency comparison coefficient.

[0007] The dual-loop predictive control module is used to execute a dynamic setpoint drift strategy based on the energy efficiency comparison coefficient. It is configured to: when the energy efficiency comparison coefficient indicates that the shear heating efficiency is better than the electric heating efficiency, actively reduce the temperature setpoint of the temperature control loop and simultaneously adjust the speed command of the speed control loop, so as to force the material to maintain the apparent viscosity value within the preset melt mass constraint range through the endogenous heat generated by shear friction.

[0008] The execution feedback module is used to convert the adjusted temperature setpoint and speed command into low-level control signals, send them to the heating actuator and motor drive mechanism, and monitor the response changes of the operating status data in real time to correct the non-Newtonian fluid rheological model.

[0009] Optionally, the edge rheological solution module includes:

[0010] The torque mapping unit is used to map the motor current value to an electromagnetic torque value after removing the no-load loss component.

[0011] The viscosity estimation unit is used to receive the electromagnetic torque value and the screw speed value, and calculate the apparent viscosity value by combining the geometric parameters of the extruder.

[0012] The viscosity estimation unit is configured to monitor the rate of change of the apparent viscosity value, and when the rate of change exceeds a preset steady-state threshold, it triggers adaptive correction of the rheological model parameters.

[0013] Optional, the thermal engine efficiency decoupling module includes:

[0014] The electric heating energy consumption calculation unit is used to calculate the electric heating power consumption required to generate a unit of heat based on the heating response characteristics of the current temperature zone.

[0015] The shear energy consumption calculation unit is used to calculate the increase in motor drive power required to generate shear heat equivalent to the unit heat by increasing the rotational speed, based on the non-Newtonian fluid rheological model.

[0016] The comparison decision unit is used to compare the electric heating power consumption with the motor drive power increment. If the motor drive power increment is less than the electric heating power consumption, it is determined that the current region is dominated by shear heat, and the energy efficiency comparison coefficient that tends to generate shear heat is output.

[0017] Optionally, the dual-loop predictive control module includes:

[0018] The setpoint drift unit is used to receive the energy efficiency comparison coefficient. When the shear heat generation efficiency is better than the electric heating efficiency, the setpoint value of the barrel heating zone is gradually reduced according to the preset gradient step size until the shear heat generation efficiency and the electric heating efficiency reach the balance point or reach the preset minimum safe temperature limit.

[0019] The speed compensation unit is used to calculate the viscosity increase trend caused by the temperature drop in response to the decrease of the temperature setpoint, and generate a positive speed compensation command to increase the shear heat input, offset the reduction of external heating, and maintain the total enthalpy balance of the system.

[0020] Optionally, the dual-loop predictive control module also includes:

[0021] An anti-countermeasures logic unit is used to monitor the output duty cycle of the heater and the output duty cycle of the cooling fan in the same temperature zone in real time.

[0022] The anti-confrontation logic unit is configured to: when the output duty cycle of the heater and the output duty cycle of the cooling fan are both greater than zero, calculate the current energy consumption value of the heater and the current energy consumption value of the cooling fan, forcibly block the output signal of the one with the larger energy consumption value, and re-plan the temperature setpoint according to the current apparent viscosity value to eliminate the energy loss caused by the heat-cold confrontation.

[0023] Optionally, the execution feedback module includes:

[0024] The thermal inertia prediction unit is used to establish a large-hysteresis heat conduction model based on the historical response curves of the heating actuator.

[0025] The overshoot suppression unit is used to predict the overshoot of the barrel temperature in advance using the large hysteresis heat conduction model when the speed command undergoes a step change that causes a sudden increase in shear heat, and outputs a pre-control command to cut off heating or start air cooling in advance before the actual temperature rises, so as to prevent degradation caused by uncontrolled material temperature.

[0026] Optionally, the system may also include:

[0027] The safety interlock module is used to monitor the pressure value of the machine head and the current value of the motor in real time;

[0028] The safety interlock module is configured to immediately disable the energy-saving strategy of the dual-loop predictive control module when the pressure value of the machine head exceeds the preset pressure safety threshold or the current value of the motor exceeds the preset overload threshold, forcibly switch the system to the preset safe homogenization production mode, and reset the temperature setpoint and speed command to the rated process parameters.

[0029] Optionally, the edge rheology calculation module is also configured with:

[0030] An impurity fluctuation filtering unit is used to identify high-frequency pressure pulse signals in the pressure value of the machine head;

[0031] When the high-frequency pressure pulse signal is detected, the impurity fluctuation filtering unit determines that there is material impurity interference and temporarily freezes the update of the apparent viscosity value, keeping the current control strategy unchanged until the high-frequency pressure pulse signal disappears, so as to avoid the pressure fluctuation caused by impurities from misleading the energy-saving control logic.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. This invention constructs a thermo-mechanical energy efficiency decoupling model to quantitatively compare the energy efficiency differences between electric heating and mechanical shear heat generation in real time. When shear heat generation efficiency is dominant, the system actively executes a dynamic setpoint drift strategy, which reduces the barrel temperature setpoint and simultaneously increases the screw speed, forcing the material to maintain a molten state by relying on endogenous heat generated by internal friction. This mechanism breaks the suppression of mechanical heat by traditional constant temperature control, converting shear heat, which was originally considered an interference, into effective energy, significantly reducing the overall energy consumption of the cable extrusion process.

[0034] 2. This invention utilizes an edge rheology calculation module to establish a virtual rheological state characterization, enabling real-time back-calculation of the material's apparent viscosity based on motor current and rotation speed without the need for an expensive online rheometer. The system can adaptively correct the rheological model parameters according to the viscosity change rate, ensuring real-time matching between the control logic and the actual material characteristics. This upgrades the control core from a single temperature dimension to a more fundamental viscosity dimension, effectively solving the problem of unstable extrusion quality caused by batch fluctuations in materials and ensuring the consistency of product wire diameter.

[0035] 3. This invention introduces a thermal inertia prediction and countermeasure elimination mechanism, which solves the control problems of large hysteresis and heat-cold offset in extruders. By establishing a large hysteresis heat conduction model, the system can predict the temperature rise trend in advance when the speed adjustment causes a sudden increase in shear heat, and intervene in advance to suppress overshoot and prevent degradation of heat-sensitive materials. At the same time, it forcibly blocks the synchronous operation of heating and air cooling, reconstructs the temperature equilibrium point according to the real-time viscosity, eliminates the energy loss between actuators, and greatly improves the thermodynamic stability of the system.

[0036] 4. This invention integrates safety interlock and impurity fluctuation filtering functions, enhancing the system's industrial-grade robustness. By identifying high-frequency pressure pulses, the system can accurately distinguish between impurity interference and actual viscosity changes, avoiding misleading control logic due to pressure fluctuations caused by impurities. Simultaneously, when the machine head pressure or motor current exceeds the limit, the energy-saving strategy is immediately disabled and a forced switch to a safe homogenization production mode is initiated. This dual protection mechanism ensures that while pursuing ultimate energy efficiency, equipment damage is effectively prevented, achieving a balance between high efficiency and safety. Attached Figure Description

[0037] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0038] Figure 1 This is a structural diagram of the system of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0040] Example 1:

[0041] Please see Figure 1 An energy-saving control system for cable extrusion processes based on edge computing includes:

[0042] The multi-dimensional data acquisition module is used to acquire the operating status data of the extruder system in real time via fieldbus. The operating status data includes the motor current value of the drive motor, the screw speed value, the current temperature value of each temperature zone of the barrel, and the pressure value of the die head.

[0043] The edge rheology calculation module is used to calculate the apparent viscosity of the current material in real time based on the motor current value and screw speed value, using a preset non-Newtonian fluid rheology model, and to construct a virtual rheological state characterization.

[0044] The thermal engine energy efficiency decoupling module is used to calculate the electric heating energy efficiency index and the shear heat generation energy efficiency index under the current operating conditions based on the operating status data, and to calculate the ratio of the shear heat generation energy efficiency index to the electric heating energy efficiency index, and generate the energy efficiency comparison coefficient.

[0045] The dual-loop predictive control module is used to execute a dynamic setpoint drift strategy based on the energy efficiency comparison coefficient. It is configured to: when the energy efficiency comparison coefficient indicates that the shear heating efficiency is better than the electric heating efficiency, actively reduce the temperature setpoint of the temperature control loop and simultaneously adjust the speed command of the speed control loop, so as to force the material to maintain the apparent viscosity value within the preset melt mass constraint range through the endogenous heat generated by shear friction.

[0046] The execution feedback module is used to convert the adjusted temperature setpoint and speed command into low-level control signals, send them to the heating actuator and motor drive mechanism, and monitor the response changes of the operating status data in real time to correct the non-Newtonian fluid rheological model.

[0047] This embodiment elaborates on the basic architecture and core data flow logic of the above system, aiming to solve the problem of low energy efficiency caused by the separation of mechanical energy and thermal energy control in traditional extrusion processes;

[0048] The system initiates the multidimensional data acquisition module, establishing a synchronous communication link with the underlying devices via EtherCAT or Profinet fieldbus to acquire key process variables at millisecond intervals. During this process, the system focuses on the following parameter variables:

[0049] Motor current value The source is the real-time feedback from the current transformer inside the frequency converter. Its physical meaning is the instantaneous load current that drives the screw to rotate, and the unit is A.

[0050] Screw speed value The source is feedback from the motor encoder, and its physical meaning is the screw's revolutions per minute (rpm), directly related to the shear rate, with the unit being rpm; simultaneously, the system defines the screw's angular velocity. The unit is rad / s, used for subsequent rheological formula calculations;

[0051] Head pressure value The data is collected by a melt pressure sensor and its physical meaning is the back pressure of the melt flowing through the die head, which characterizes the extrusion stability. The unit is MPa.

[0052] The edge rheology calculation module accesses the above data and constructs a so-called virtual rheological state representation. This representation is essentially a digital mapping of the material melting and flow state obtained by back-calculating the electromechanical response characteristics of the motor in the absence of online rheometer hardware, enabling the system to use viscosity rather than simply temperature as the control core.

[0053] The thermal engine energy efficiency decoupling module is involved to calculate the energy efficiency ratio comparison coefficient. This coefficient is a dimensionless parameter used to quantify the efficiency difference in converting unit energy into the enthalpy of plasticization of materials; in response to The dual-loop predictive control module determines the current rheological state and introduces shear heat by increasing the screw speed, which is more energy-efficient and conducive to homogenization than turning on the resistance heating coil. It then performs dynamic setpoint drift. This strategy abandons the traditional constant temperature control logic and allows the barrel temperature setpoint to float downward within the constraint range that meets the extrusion quality. This forces the material to maintain the apparent viscosity value within the preset melt quality constraint range through the endogenous heat generated by the screw shear friction.

[0054] The execution feedback module converts the decision into PWM duty cycle or analog voltage, and drives the device to operate in a closed loop.

[0055] This embodiment constructs a control architecture based on the first principle of energy conversion. By converting the screw frictional heat, which was originally considered a disturbance, into an effective source of plasticizing energy, in the cable extrusion scenario, the system no longer rigidly adheres to the temperature setpoint, but dynamically seeks the optimal ratio of mechanical shear energy to electric heating energy. This thermo-mechanical coupling control strategy significantly reduces the overall energy consumption per unit output and improves the thermodynamic stability of the extrusion process by reducing the conflict between external forced heating and internal shear heat generation.

[0056] Example 2:

[0057] The edge rheological solution module includes:

[0058] The torque mapping unit is used to map the motor current value to an electromagnetic torque value after removing the no-load loss component.

[0059] The viscosity estimation unit receives the electromagnetic torque value and screw speed value, and calculates the apparent viscosity value by combining the geometric parameters of the extruder. The viscosity estimation unit is configured to monitor the rate of change of the apparent viscosity value. When the rate of change exceeds the preset steady-state threshold, it triggers the adaptive correction of the rheological model parameters.

[0060] This embodiment further refines the internal computational logic of the edge rheology solution module. The core lies in how to achieve high-precision soft measurement and closed-loop correction of rheology model parameters without a direct viscosity sensor.

[0061] The torque mapping unit performs current signal cleaning and mapping. To accurately obtain the effective torque acting on the material, the system introduces effective electromagnetic torque. Model:

[0062]

[0063] The source is calculated, and the physical meaning is the effective torque that actually acts on the material shearing, with the unit being N·m;

[0064] The source is preset by the parameters on the motor nameplate, and its physical meaning is the motor torque constant, with the unit being N·m / A;

[0065] The source is a lookup value obtained through a pre-conducted no-load calibration experiment; its physical meaning is the current rotational speed. The mechanical no-load current loss is expressed in amperes (A).

[0066] The source is the equipment transmission chain parameter, and its physical meaning is the mechanical transmission efficiency constant of the gearbox and coupling;

[0067] The viscosity estimation unit back-calculates the real-time apparent viscosity value based on actual operating conditions. The dimensional logic here has been corrected to conform to the principles of rheology, where Angular velocity:

[0068]

[0069] The source is calculated, and the physical meaning is the actual apparent viscosity derived from the current torque, with the unit being Pa·s;

[0070] The source is a preset constant calculated based on the combined screw diameter, screw channel depth, screw ridge width, and effective length of the homogenization section. This constant is set based on the assumption that the extruder's metering section is in a full-flow state. Its physical meaning is the screw's comprehensive geometric shape factor, and its dimensions are designed as follows: Verification is as follows: Torque unit Multiply get ,unit Divide by angular velocity ,unit The final unit is This satisfies the consistency of dimensions;

[0071] The source is the screw speed, which needs to be converted to angular velocity in rad / s for calculation in this formula;

[0072] Based on this, in order to achieve adaptive correction of the rheological model parameters, a theoretical viscosity prediction formula based on a power-law model is simultaneously run within the system:

[0073]

[0074] Consistency coefficient, initial value provided by the material property table;

[0075] Non-Newtonian index, initial values ​​are provided by the material property table;

[0076] The source is the screw flow channel geometric factor, and its physical meaning is the proportionality coefficient that converts rotational angular velocity into shear rate;

[0077] The system continuously monitors the rate of change of apparent viscosity. ; in response to the absolute value of the rate of change exceeding a preset steady-state threshold. For example, if the pressure is 5 Pa·s / s and the duration exceeds the judgment period, such as 3 seconds, the system determines that the material batch has changed and triggers the rheological model parameters. Adaptive correction iteration:

[0078]

[0079] in, Index for the current control cycle; The preset adaptive gain coefficient has a value of 0.01-0.05. To prevent the value from being divided by zero and reaching a minimum, the value is taken as follows: Used to prevent [damage] during startup or under no-load conditions. Approaching zero leads to computational overflow; this gradient descent algorithm utilizes the current... and Refitting the non-Newtonian exponent This allows the theoretical model to approximate the actual physical state, ensuring the accuracy of subsequent predictive control.

[0080] This embodiment achieves accurate conversion of the motor's electrical signal into a material rheological signal by eliminating no-load losses and combining them with a modified geometric factor formula, and clarifies the non-Newtonian exponent. The online iterative update algorithm solves the problem of model distortion caused by material batch fluctuations in traditional control.

[0081] Example 3:

[0082] The thermal efficiency decoupling module includes:

[0083] The electric heating energy consumption calculation unit is used to calculate the electric heating power consumption required to generate a unit of heat based on the heating response characteristics of the current temperature zone.

[0084] The shear energy consumption calculation unit is used to calculate the increase in motor drive power required to generate shear heat equivalent to a unit of heat by increasing the rotational speed, based on a non-Newtonian fluid rheological model.

[0085] The comparison decision unit is used to compare the power consumption of electric heating with the increase in motor drive power. If the increase in motor drive power is less than the power consumption of electric heating, it is determined that the current situation is in the shear heat dominance range, and the energy efficiency comparison coefficient that tends to generate heat from shear is output.

[0086] This embodiment describes in detail the decision logic of the heat engine energy efficiency decoupling module, aiming to quantify the marginal cost of the two energy sources in real time;

[0087] The electric heating energy consumption calculation unit introduces an electric heating efficiency index. The calculation logic is as follows:

[0088]

[0089] The source is the process setting constant, and its physical meaning is the heat power required to maintain the target temperature in the current temperature range, with the unit being W;

[0090] The source is calculated based on the square product of the SSR output duty cycle and the current measured grid voltage. The physical meaning is the actual increase in electrical power consumed by the heater, in W, to compensate for the power calculation error caused by grid voltage fluctuations.

[0091] The source is determined through thermal step response testing, and its physical meaning is the combined efficiency of the heater's electrothermal conversion and conduction. It should be noted that due to significant losses from radiation and convection heat dissipation in the external resistance heater, its effective heating efficiency is... Typical values ​​are usually between 0.4 and 0.6; while shear heat generation is heat generated by molecular friction within the material, without environmental dissipation along the heat transfer path. Therefore, under specific high-viscosity conditions, the effective plasticizing enthalpy generated per unit of electrical energy is often higher than that generated by external heating. The physical basis may be greater than 1;

[0092] The shear energy consumption calculation unit calculates the shear heat efficiency index based on the principle of viscous dissipation. :

[0093]

[0094] The source is based on calculations using a rheological model;

[0095] The source is based on the torque model and its physical meaning is the increase in grid-side input power consumed by the motor to generate the shear increment, in W.

[0096] The value is derived from the overall efficiency of the motor drive system (including inverter efficiency and motor efficiency), with a preset value of 0.85-0.95.

[0097] The source is the real-time apparent viscosity value output by the edge rheology calculation module of Example 2, in Pa·s, which maintains consistency with the parameter definition of the previous example.

[0098] The source is the shear rate, determined by the screw rotation speed. Multiply by flow channel geometry factor The result is calculated, and the unit is... ;

[0099] The source is the barrel geometry parameters; its physical meaning is the shear flow field volume; the unit is... ;

[0100] Comparison of energy efficiency comparison coefficients generated by decision-making units ;

[0101] In response to In other words, the thermal benefits brought by the increase in motor drive power are more cost-effective than electric heating. The system determines that it is currently in the range where shear heat is dominant and outputs a coefficient that tends to generate heat from shear, instructing the subsequent control unit to prioritize increasing the speed rather than increasing the heating duty cycle.

[0102] This embodiment elevates energy-saving control from empiricism to the level of physical model optimization. By comparing the energy efficiency indices of electrothermal and shear thermal in real time, the system can keenly detect energy consumption gaps under different operating conditions, ensuring that every control action—whether cooling or speeding up—can minimize total power consumption while maintaining the conservation of the system's total enthalpy. Especially in high-viscosity material processing scenarios, this strategy can fully tap the potential of shear thermal.

[0103] Example 4:

[0104] The dual-loop predictive control module includes:

[0105] The setpoint drift unit is used to receive the energy efficiency comparison coefficient. When the shear heating efficiency is better than the electric heating efficiency, the temperature setpoint of the barrel heating zone is gradually reduced according to the preset gradient step size until the shear heating efficiency and the electric heating efficiency reach the balance point or reach the preset minimum safe temperature limit.

[0106] The speed compensation unit is used to respond to the decrease in temperature setpoint, calculate the viscosity increase trend caused by the temperature drop, and generate a positive speed compensation command to increase shear heat input, offset the decrease in external heating, and maintain the total enthalpy balance of the system.

[0107] This embodiment specifies the execution strategy of the dual-loop predictive control module, focusing on the coordinated operation of cooling and speed-up and the underlying energy conservation calculation.

[0108] The setpoint drift unit receives signals that tend to generate heat through shear. At that time, initiate the gradient descent drift algorithm:

[0109]

[0110] The source is the set value of the current control cycle, and its physical meaning is the barrel temperature setpoint, with the unit being °C.

[0111] The source is a preset value, with a typical value of 0.1-0.5. Its physical meaning is the drift step size coefficient, and its unit is defined as ℃ to ensure the dimensional consistency of the calculation results.

[0112] The source is determined by the melting point of the material and the maximum permissible torque. Its physical meaning is the minimum safe temperature limit, which serves as a hard constraint for downward exploration.

[0113] The speed compensation unit responds immediately to the decrease in the temperature setpoint; in order to maintain the overall enthalpy balance of the system, the reduction in external heat input due to the decrease in the temperature setpoint must be calculated. And convert it into the required mechanical shear power increment;

[0114] Calculate the heat power gap:

[0115]

[0116] Specific heat capacity of material, preset constant, unit ;

[0117] The current mass flow rate of the extruder, through Estimate, unit: kg / s;

[0118] : This is the screw geometry conveying factor, determined by the screw lead and fill factor, and is measured in units of... ;

[0119] : This represents the melt density, in units of ;

[0120] Calculate speed compensation command Based on the law of conservation of energy, assuming that the increased mechanical shear power is completely dissipated into the melt energy and mechanical losses are ignored, that is... and shear power , here Let ω be the angular velocity in rad / s. The required rotational speed increment is calculated as follows:

[0121]

[0122]

[0123] : The effective electromagnetic torque measured so far, in N·m;

[0124] : The calculated increment of angular velocity, in rad / s;

[0125] : The converted speed command increment, in rpm;

[0126] The system synchronously outputs the reduced temperature setpoint. With the increased speed command This means that the additional frictional heat generated by the increased shear rate exactly offsets the heat reduction caused by external heating.

[0127] This embodiment, through this active drift and compensation mechanism, uses specific formulas for specific heat capacity and mass flow rate to quantify the substitution relationship between thermal energy and mechanical energy, and rigorously handles the physical unit conversion between power and rotational speed. It cleverly shifts energy supply from inefficient external heating to efficient internal shearing, achieving a dual improvement in energy efficiency and quality.

[0128] Example 5:

[0129] The dual-loop predictive control module also includes:

[0130] The anti-heat cancellation logic unit is used to monitor the output duty cycle of the heater and the output duty cycle of the cooling fan in the same temperature zone in real time. The anti-heat cancellation logic unit is configured to: when the output duty cycle of the heater and the output duty cycle of the cooling fan are both greater than zero, calculate the current energy consumption value of the heater and the current energy consumption value of the cooling fan, forcibly block the output signal of the one with the larger energy consumption value, and re-plan the temperature setpoint according to the current apparent viscosity value to eliminate the energy loss caused by the heat-cooling opposition.

[0131] This embodiment adds an adversarial elimination logic unit to the dual-loop control, aiming to solve the common problem of hot and cold cancellation in existing PID control.

[0132] The unit monitors the output duty cycle of the heater in the same temperature zone in real time. Duty cycle of cooling fan output ; in response to detection and Simultaneous occurrences indicate a serious waste of energy in the countermeasures;

[0133] The system performs energy consumption calculations and obtains the current energy consumption values ​​of the heaters. Current energy consumption of cooling fan ;

[0134] The system executes a blocking arbitration; in response to the detection of a heat-cold conflict, regardless of which side consumes more energy, it forcibly resets the output signals of both the heater and the cooling fan to zero simultaneously. and This is to cut off sources of energy waste; based on this, if it is determined that the cooling fan must be turned on, it means that the shear heat is sufficient to maintain or even exceed the current set temperature. The unit will then recalculate based on the current apparent viscosity value, i.e., adjust the temperature setpoint. Equal to the current actual melt temperature This allows the heating and fan to be turned off simultaneously, balancing the shear heat through natural heat dissipation.

[0135] This embodiment eliminates the absurd situation of simultaneous heating and cooling from the control logic level, removing the biggest hidden waste in the control system and ensuring that every joule of energy is used to process materials, rather than being canceled out between the heater and the fan. In actual production, this strategy can significantly reduce the frequency of fan start-up, extend the life of actuators, and allow the system to operate in a more natural thermal equilibrium state.

[0136] Example 6:

[0137] The execution feedback module includes:

[0138] The thermal inertia prediction unit is used to establish a large-hysteresis heat conduction model based on the historical response curves of the heating actuator.

[0139] The overshoot suppression unit is used to predict the overshoot of the barrel temperature in advance when a step change in the speed command causes a sudden increase in shear heat. It uses a large hysteresis heat conduction model to predict the overshoot of the barrel temperature in advance and outputs a pre-control command to cut off heating or start air cooling before the actual temperature rises, so as to prevent degradation caused by runaway material temperature.

[0140] This embodiment describes in detail the feedforward prediction function in the execution feedback module, taking into account the physical characteristics of large hysteresis in extruders.

[0141] The thermal inertia prediction unit establishes a large-hysteresis heat conduction model based on system identification. :

[0142]

[0143] The source is obtained through step response testing, and its physical meaning is pure time delay, which is usually on the order of minutes;

[0144] : is the Laplace transform operator. It is a natural constant;

[0145] The source is system identification, and the physical meaning is the heat conduction time constant;

[0146] The source is the calculation of the steady-state value of the step response, and its physical meaning is the static gain of the heating system, which represents the amount of steady-state temperature change caused by a unit change in input.

[0147] Overshoot suppression unit monitors speed command The system responds to a step change in speed command, such as a sudden acceleration to increase shear heat. The system determines that shear heat will increase instantaneously, but the temperature sensor... Because of thermal inertia, it takes several minutes to reflect the temperature rise;

[0148] At this point, the unit utilizes the aforementioned model to determine the speed command issued. Time, calculate in advance Predicted barrel temperature at any time The specific discretization prediction formula is as follows:

[0149]

[0150] in, The measured temperature at the current moment. The number of pure time delay periods. The sampling period is This represents the step change in the speed command;

[0151] In response to If the temperature exceeds the allowable range, the unit will output a pre-control command before the actual temperature rises, such as cutting off heating in advance or briefly turning on the air-cooling pulse to intercept the upcoming temperature overshoot.

[0152] This embodiment effectively solves the industry problem of temperature control lag in extruder control. By mathematically predicting the physical process, it avoids temperature overshoot caused by speed adjustment, prevents heat-sensitive materials from degrading or scorching due to instantaneous overheating, and ensures production safety when implementing aggressive energy-saving strategies, such as significant speed increases, enabling the system to operate under boundary conditions.

[0153] Example 7:

[0154] The system also includes:

[0155] The safety interlock module is used to monitor the machine head pressure and motor current values ​​in real time. The safety interlock module is configured to immediately disable the energy-saving strategy of the dual-loop predictive control module when the machine head pressure exceeds the preset pressure safety threshold or the motor current exceeds the preset overload threshold, forcibly switch the system to the preset safe homogenization production mode, and reset the temperature setpoint and speed command to the rated process parameters.

[0156] This embodiment describes the system's safety fallback mechanism, namely the execution logic of the safety interlock module;

[0157] The module monitors the pressure value of the machine head in real time. and motor current value And set hard constraint boundaries:

[0158] Pressure safety threshold The source is 85% of the bearing limit of the machine head flange, and its physical meaning is the upper limit of pressure to prevent mechanical bursting.

[0159] Overload threshold The source is 95% of the motor's rated current, and its physical meaning is the upper limit of the current to prevent the motor from burning out.

[0160] If any indicator exceeds its limit, the module determines that the system is in a non-steady-state risk zone; at this time, regardless of the energy efficiency comparison coefficient... How to instruct the module to immediately perform a circuit breaker operation:

[0161] First, implement energy-saving strategies and freeze the output of the dual-loop predictive control module;

[0162] Second, force the system to switch to the preset safe and homogenized production mode;

[0163] Third, set the temperature value and speed command Reset to the rated process parameters on the process card, i.e., the traditional conservative parameters;

[0164] Manual reset or automatic recovery of energy-saving mode is only permitted after the monitored values ​​have fallen back to a safe range and remained there for a certain period of time.

[0165] This embodiment establishes a hierarchical principle of safety first and energy saving second, ensuring the industrial-grade robustness of the system. It prevents simple energy-saving algorithms from blindly increasing speed under extreme conditions such as material blockage and insufficient cold start, which could damage equipment or cause production accidents, thus providing a necessary safety barrier for unattended automated production.

[0166] Example 8:

[0167] The edge rheological solution module is also configured with:

[0168] The impurity fluctuation filtering unit is used to identify high-frequency pressure pulse signals in the pressure value of the die head. When a high-frequency pressure pulse signal is detected, the impurity fluctuation filtering unit determines that there is material impurity interference and temporarily freezes the update of the apparent viscosity value, keeping the current control strategy unchanged until the high-frequency pressure pulse signal disappears, so as to avoid the pressure fluctuation caused by impurities from misleading the energy-saving control logic.

[0169] This embodiment addresses the problem of material impurities interfering with actual production by adding an impurity fluctuation filtering unit;

[0170] The system specifically employs a sliding window fast Fourier transform algorithm to process the collected head pressure values. Perform frequency domain analysis on the signal; set the sampling window length to... By calculating the power spectral density, the energy percentage in the frequency range of 10Hz-50Hz is extracted.

[0171] The system sets the pulse frequency threshold. and energy percentage threshold In response to the detection that the energy proportion in the aforementioned high-frequency range is greater than ; Based on the signal characteristics, the system determines that the current pressure fluctuation is not caused by viscosity changes, but by high-frequency pressure pulse signals caused by unmelted impurities passing through the die head flow channel.

[0172] The unit executes a freeze command, temporarily halting the updating of the apparent viscosity value and subsequent adjustments to the control strategy, while maintaining the current temperature and speed settings unchanged.

[0173] Only when the high-frequency signal disappears, indicating that the impurities have been removed, does the system resume normal rheological calculation and closed-loop control logic;

[0174] This embodiment improves the system's anti-interference capability in complex raw material environments. In particular, for cable extrusion scenarios using recycled materials, this mechanism avoids pressure fluctuations caused by occasional impurities from being misjudged as viscosity increases and erroneously triggering deceleration or heating commands. It prevents the system from entering an unnecessary oscillation state and ensures the smoothness of the control process and the consistency of the product wire diameter.

[0175] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An energy-saving control system for cable extrusion process based on edge computing, characterized in that: include: The multi-dimensional data acquisition module is used to acquire the operating status data of the extruder system in real time via fieldbus. The operating status data includes the motor current value of the drive motor, the screw speed value, the current temperature value of each temperature zone of the barrel, and the die head pressure value. The edge rheology calculation module is used to calculate the apparent viscosity of the current material in real time based on the motor current value and the screw speed value using a preset non-Newtonian fluid rheology model, and to construct a virtual rheological state characterization. The thermal engine energy efficiency decoupling module is used to calculate the electric heating energy efficiency index and the shear heat generation energy efficiency index under the current operating conditions based on the operating status data, and to calculate the ratio of the shear heat generation energy efficiency index to the electric heating energy efficiency index to generate an energy efficiency comparison coefficient. The dual-loop predictive control module is used to execute a dynamic setpoint drift strategy based on the energy efficiency comparison coefficient. It is configured to: when the energy efficiency comparison coefficient indicates that the shear heating efficiency is better than the electric heating efficiency, actively reduce the temperature setpoint of the temperature control loop and simultaneously adjust the speed command of the speed control loop, so as to force the material to maintain the apparent viscosity value within the preset melt mass constraint range through the endogenous heat generated by shear friction. The execution feedback module is used to convert the adjusted temperature setpoint and speed command into low-level control signals, send them to the heating actuator and motor drive mechanism, and monitor the response changes of the operating status data in real time to correct the non-Newtonian fluid rheological model. The edge rheological calculation module includes: The torque mapping unit is used to map the motor current value to an electromagnetic torque value after removing the no-load loss component. The viscosity estimation unit is used to receive the electromagnetic torque value and the screw speed value, and calculate the apparent viscosity value by combining the geometric parameters of the extruder. The viscosity estimation unit is configured to monitor the rate of change of the apparent viscosity value, and trigger an adaptive correction of the non-Newtonian exponent when the rate of change exceeds a preset steady-state threshold. The heat engine energy efficiency decoupling module includes: The electric heating energy consumption calculation unit is used to calculate the electric heating power consumption required to generate a unit of heat based on the heating response characteristics of the current temperature zone. The shear energy consumption calculation unit is used to calculate the increase in motor drive power required to generate shear heat equivalent to the unit heat by increasing the rotational speed, based on the non-Newtonian fluid rheological model. The comparison decision unit is used to compare the electric heating power consumption with the motor drive power increment. If the motor drive power increment is less than the electric heating power consumption, it is determined that the current region is dominated by shear heat, and the energy efficiency comparison coefficient that tends to generate shear heat is output. The dual-loop predictive control module includes: The setpoint drift unit is used to receive the energy efficiency comparison coefficient. When the shear heat generation efficiency is better than the electric heating efficiency, the setpoint value of the barrel heating zone is gradually reduced according to the preset gradient step size until the shear heat generation efficiency and the electric heating efficiency reach the balance point or reach the preset minimum safe temperature limit. The speed compensation unit is used to calculate the viscosity increase trend caused by the temperature drop in response to the decrease of the temperature setpoint, and generate a positive speed compensation command to increase the shear heat input, offset the reduction of external heating, and maintain the total enthalpy balance of the system. The system introduces effective electromagnetic torque Model: The source is calculated, and the physical meaning is the effective torque that actually acts on the material shearing, with the unit being N·m; The source is preset by the parameters on the motor nameplate, and its physical meaning is the motor torque constant, with the unit being N·m / A; The source is the real-time feedback from the current transformer inside the frequency converter. Its physical meaning is the instantaneous load current that drives the screw to rotate, and the unit is A. The source is a lookup value obtained through a pre-conducted no-load calibration experiment; its physical meaning is the current rotational speed. The mechanical no-load current loss is expressed in amperes (A). The source is the equipment transmission chain parameter, and its physical meaning is the mechanical transmission efficiency constant of the gearbox and coupling; The viscosity estimation unit back-calculates the real-time apparent viscosity value based on actual operating conditions. The dimensional logic here has been corrected to conform to the principles of rheology: The source is calculated, and the physical meaning is the actual apparent viscosity derived from the current torque, with the unit being Pa·s; The source is a preset constant calculated based on the comprehensive screw diameter, screw groove depth, screw ridge width, and effective length of the homogenized section. Its physical meaning is the comprehensive geometric shape factor of the screw, and its dimensions are designed as follows: ; The source is the screw angular velocity; To achieve adaptive correction for non-Newtonian exponents, the system simultaneously runs a theoretical viscosity prediction formula based on a power-law model: Consistency coefficient, initial value provided by the material property table; Non-Newtonian exponents, initial values ​​are provided by the material property table; The source is the screw flow channel geometric factor, and its physical meaning is the proportionality coefficient that converts rotational angular velocity into shear rate; The system continuously monitors the rate of change of apparent viscosity. ; in response to the absolute value of the rate of change exceeding a preset steady-state threshold. If the duration exceeds the judgment period, the system determines that the material batch has changed, triggering a non-Newtonian exponent. Adaptive correction iteration: in, Index for the current control cycle; The preset adaptive gain coefficient has a value of 0.01-0.

05. To prevent the value from being divided by zero and reaching a minimum, the value is taken as follows: Used to prevent [damage] during startup or under no-load conditions. Approaching zero leads to computational overflow; this gradient descent algorithm utilizes the current... and Refitting the non-Newtonian exponent This allows the theoretical model to approximate the actual physical state, ensuring the accuracy of subsequent predictive control. The electric heating energy consumption calculation unit introduces an electric heating efficiency index. The calculation logic is as follows: The source is the process setting constant, and its physical meaning is the heat power required to maintain the target temperature in the current temperature range, with the unit being W; The source is calculated based on the square product of the SSR output duty cycle and the current measured grid voltage. The physical meaning is the actual increase in electrical power consumed by the heater, and the unit is W. The source is the calibration through thermal step response testing, and its physical meaning is the combined efficiency of the heater's electrothermal conversion and conduction. The shear energy consumption calculation unit calculates the shear heat efficiency index based on the principle of viscous dissipation. : The source is based on calculations using a rheological model; The source is based on the torque model and its physical meaning is the increase in grid-side input power consumed by the motor to generate the shear increment, in W. The value is derived from the overall efficiency of the motor drive system, with a preset value of 0.85-0.

95. The source is the real-time apparent viscosity value output by the edge rheology calculation module, in Pa·s, which is consistent with the previous parameter definition. The source is the shear rate, determined by the screw rotation speed. Multiply by flow channel geometry factor The result is calculated, and the unit is... ; The source is the barrel geometry parameters; its physical meaning is the shear flow field volume; the unit is... .

2. The energy-saving control system for cable extrusion process based on edge computing according to claim 1, characterized in that: The dual-loop predictive control module also includes: An anti-countermeasures logic unit is used to monitor the output duty cycle of the heater and the output duty cycle of the cooling fan in the same temperature zone in real time. The anti-confrontation logic unit is configured to: when the output duty cycle of the heater and the output duty cycle of the cooling fan are both greater than zero, calculate the current energy consumption value of the heater and the current energy consumption value of the cooling fan, forcibly block the output signal of the one with the larger energy consumption value, and re-plan the temperature setpoint according to the current apparent viscosity value to eliminate the energy loss caused by the heat-cold confrontation.

3. The energy-saving control system for cable extrusion process based on edge computing according to claim 1, characterized in that: The execution feedback module includes: The thermal inertia prediction unit is used to establish a large-hysteresis heat conduction model based on the historical response curves of the heating actuator. The overshoot suppression unit is used to predict the overshoot of the barrel temperature in advance using the large hysteresis heat conduction model when the speed command undergoes a step change that causes a sudden increase in shear heat, and outputs a pre-control command to cut off heating or start air cooling in advance before the actual temperature rises, so as to prevent degradation caused by uncontrolled material temperature.

4. The energy-saving control system for cable extrusion process based on edge computing according to claim 1, characterized in that: The system also includes: The safety interlock module is used to monitor the pressure value of the machine head and the current value of the motor in real time; The safety interlock module is configured to immediately disable the energy-saving strategy of the dual-loop predictive control module when the pressure value of the machine head exceeds the preset pressure safety threshold or the current value of the motor exceeds the preset overload threshold, forcibly switch the system to the preset safe homogenization production mode, and reset the temperature setpoint and speed command to the rated process parameters.

5. The energy-saving control system for cable extrusion process based on edge computing according to claim 1, characterized in that: The edge rheology calculation module is also configured with: An impurity fluctuation filtering unit is used to identify high-frequency pressure pulse signals in the pressure value of the machine head; When the high-frequency pressure pulse signal is detected, the impurity fluctuation filtering unit determines that there is material impurity interference and temporarily freezes the update of the apparent viscosity value, keeping the current control strategy unchanged until the high-frequency pressure pulse signal disappears, so as to avoid the pressure fluctuation caused by impurities from misleading the energy-saving control logic.

Images