A cable extruder screw rotation speed self-adaptive control system and method

Abstract

The application provides a cable extruder screw rotation speed adaptive control system and method, and relates to the technical field of cable manufacturing automation control. The method comprises: acquiring multi-source operation parameters including screw operation parameters, traction operation parameters, product state parameters, temperature parameters and pressure parameters and a current rotation speed value; generating a first rotation speed adjustment amount based on the deviation direction, deviation degree, change rate and change trend of the screw operation parameters; generating a second rotation speed adjustment amount based on the change amount of the traction operation parameters; generating a third rotation speed adjustment amount when the product state deviation amount meets a preset triggering condition; generating fourth and fifth rotation speed adjustment amounts based on the temperature deviation amount and the pressure deviation amount respectively; and adding the five adjustment amounts to the current rotation speed value to obtain a target rotation speed value to control the screw rotation. The application realizes accurate and stable control of the cable extrusion process screw rotation speed through the adaptive control strategy combining multi-parameter cooperation and trend prediction.

Description

Technical Field

[0001] This application relates to the field of automated control technology in cable manufacturing, and more specifically, to an adaptive control system and method for the screw speed of a cable extruder. Background Technology

[0002] Currently, cable extruders are key equipment in wire and cable production, and the precise control of their screw speed directly determines the extrusion quality and production efficiency of the insulation and sheath layers. Traditional cable extrusion control mainly relies on manual experience to adjust the main extruder speed to change the extrusion flow rate. Operators manually adjust the speed based on experience and visual inspection of the wire diameter. This method has significant limitations: manual experience is difficult to standardize, leading to poor product quality consistency; operators' untimely control of wire diameter, coupled with factors such as changes in core tension, uneven distribution of rubber in the barrel, changes in rubber viscosity due to unstable barrel temperature, and drift in traction and main extruder speed, all result in unstable cable cross-sectional diameter and low product qualification rate; at the same time, it also causes rubber waste and increases production costs. To overcome these shortcomings, the industry has gradually introduced automated control technology. Currently, most polymer processing extruders are equipped with PID controllers, mainly used for controlling screw speed and barrel temperature. Based on this, automatic control systems based on wire diameter feedback have emerged, which detect the wire diameter in real time and feed it back to the controller to automatically adjust the extrusion flow rate; other solutions use high-precision weighing devices to obtain the material extrusion amount and combine it with the outer diameter data to adjust the screw speed and traction speed; still other solutions introduce fuzzy adaptive PID algorithms to cope with the nonlinearity and time-varying nature of extrusion temperature control.

[0003] However, existing control schemes still have insurmountable problems. First, the parameter tuning of traditional PID controllers largely relies on experience or engineering tuning methods. When faced with changes in rubber compound formulation and environmental temperature and humidity disturbances during extrusion, controllers with fixed parameters lack robustness and cannot respond dynamically. Second, existing schemes are mostly single-variable independent controls, failing to fully consider the strong coupling relationship between the die melt temperature and die pressure during extrusion. Third, existing control strategies are mostly "post-compensation" type, meaning adjustments are made only after deviations are detected, lacking predictive adjustment capabilities based on parameter change trends, resulting in significant control lag issues.

[0004] Therefore, there is an urgent need for an adaptive screw speed control method that can integrate multi-source operating parameters, has trend prediction capabilities, and can properly handle the temperature-pressure coupling relationship. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides an adaptive control system and method for the screw speed of a cable extruder.

[0006] In a first aspect, this application provides a method for adaptive control of the screw speed of a cable extruder, comprising:

[0007] Obtain the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed;

[0008] The first speed adjustment amount is generated based on the deviation direction of the screw operating parameters relative to their preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change.

[0009] A second speed adjustment is generated based on the change in the traction operating parameters;

[0010] The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation.

[0011] A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value.

[0012] The first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount, and the fifth speed adjustment amount are superimposed on the current speed value to obtain the target speed value, and the screw rotation is controlled by the target speed value.

[0013] Furthermore, generating the first speed adjustment amount based on the screw operating parameters includes:

[0014] Obtain the numerical sequence of the screw operating parameters at multiple consecutive sampling times;

[0015] The direction and degree of deviation of the screw operating parameters from the preset screw operating target value are calculated based on the numerical sequence.

[0016] Calculate a first-order difference sequence based on the numerical sequence, wherein the first-order difference sequence characterizes the rate of change;

[0017] The second-order difference sequence is calculated based on the first-order difference sequence, and the second-order difference sequence represents the trend of the rate of change.

[0018] The sign of the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are compared.

[0019] The magnitude of the first speed adjustment is determined based on the symbol comparison results.

[0020] Further, determining the magnitude of the first speed adjustment based on the symbol comparison result includes:

[0021] When the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are consistent, the amplitude of the first speed adjustment is increased, and the amplitude is positively correlated with the degree of deviation.

[0022] When the deviation direction is inconsistent with the direction of the first-order difference sequence, the amplitude of the first speed adjustment is reduced, and the amplitude is negatively correlated with the degree of deviation.

[0023] Furthermore, the step of generating the second speed adjustment amount based on the change in traction operating parameters includes:

[0024] The system continuously acquires the first value of the traction operation parameter at the current moment and compares it with the second value of the traction operation parameter at the previous moment. When the absolute value of the comparison result is greater than a preset change threshold, it determines that the traction operation parameter has changed value and records the current moment as the start moment.

[0025] The change in the traction operation parameter is determined based on the difference between the first value and the second value;

[0026] The speed compensation is calculated based on the change and the conveying characteristic parameters of the cable extruder, wherein the conveying characteristic parameters include at least the geometric parameters of the screw.

[0027] The speed compensation amount is used as the second speed adjustment amount, and the second speed adjustment amount is superimposed on the target speed value during the first control cycle after the start time.

[0028] Furthermore, the calculation of the speed compensation amount based on the change and the conveying characteristic parameters of the cable extruder includes:

[0029] Get the current rotational speed value;

[0030] The first unit output is determined based on the current rotation speed, the first value, and the conveying characteristic parameters.

[0031] The second unit output is determined based on the current rotational speed, the second value, and the conveying characteristic parameters.

[0032] Based on the ratio of the first unit output to the second unit output, determine the target rotational speed value corresponding to restoring the unit output to the first unit output;

[0033] The difference between the target speed value and the current speed value is used as the speed compensation amount.

[0034] Furthermore, the continuous state satisfies preset triggering conditions including:

[0035] The preset trigger condition is that the product state deviation exceeds the preset deviation range, and the duration for which the product state deviation continuously exceeds the preset deviation range reaches a preset duration threshold.

[0036] The product status deviation is the difference between the product status parameter and the preset product status target value;

[0037] Record the starting time when the product state deviation exceeds the deviation range, and start timing from the starting time to obtain the duration for which the product state deviation continuously exceeds the preset deviation range;

[0038] If the triggering conditions are not met, the third speed adjustment amount will not be generated.

[0039] Furthermore, generating a third speed adjustment amount based on the product state deviation includes:

[0040] Multiple deviation intervals are set, and each deviation interval is arranged in order of increasing product state deviation, with each deviation interval having the same width.

[0041] The target deviation range into which the product state deviation falls is determined, and the adjustment gain corresponding to the target deviation range is determined by a preset gain control algorithm. The third speed adjustment amount is obtained by multiplying the adjustment gain corresponding to the target deviation range by the product state deviation amount.

[0042] Furthermore, the step of generating the fourth and fifth speed adjustment amounts based on the temperature and pressure parameters includes:

[0043] The temperature deviation and the pressure deviation are obtained, and the first sign of the temperature deviation and the second sign of the pressure deviation are compared to determine the coupling direction between the temperature deviation and the pressure deviation.

[0044] The output directions of the fourth speed adjustment amount and the fifth speed adjustment amount are determined based on the coupling direction.

[0045] Further, determining the output directions of the fourth speed adjustment amount and the fifth speed adjustment amount based on the coupling direction includes:

[0046] When the first symbol is the same as the second symbol, the direction of the fourth speed adjustment amount is opposite to the direction of the temperature deviation amount, and the direction of the fifth speed adjustment amount is opposite to the direction of the pressure deviation amount;

[0047] When the first symbol and the second symbol are inconsistent, the direction of the larger of the temperature deviation and the pressure deviation shall be taken as the common direction of the fourth speed adjustment and the fifth speed adjustment.

[0048] The magnitude of the fourth speed adjustment is positively correlated with the absolute value of the temperature deviation, and the magnitude of the fifth speed adjustment is positively correlated with the absolute value of the pressure deviation.

[0049] Furthermore, obtaining the target rotational speed value includes:

[0050] The current speed value is used as the initial reference value, and the first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount and the fifth speed adjustment amount are sequentially superimposed on the initial reference value through a preset superposition strategy to obtain the speed value to be used, and the speed value to be used is subjected to a safety verification.

[0051] Furthermore, the safety verification of the rotational speed value to be used includes:

[0052] The speed value to be used is compared with the preset safe speed range. When the speed value to be used exceeds the safe speed range, the speed value to be used is corrected to the boundary value of the safe speed range or the current speed value is kept unchanged, and a limiting prompt signal is generated.

[0053] When the speed to be used is within the safe speed range, the speed to be used is taken as the target speed.

[0054] Secondly, this application also provides an adaptive control system for the screw speed of a cable extruder, comprising: a data acquisition module, a generation module, and an output module, wherein:

[0055] Acquisition module: used to acquire the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed;

[0056] The generation module is used to generate a first speed adjustment amount based on the direction of deviation of the screw operating parameters from its preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change.

[0057] A second speed adjustment is generated based on the change in the traction operating parameters;

[0058] The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation.

[0059] A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value.

[0060] Output module: used to superimpose the first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount and the fifth speed adjustment amount to the current speed value to obtain the target speed value, and control the screw rotation with the target speed value.

[0061] Compared with the prior art, the effective effects achieved by the present invention are as follows:

[0062] This application overcomes the limitations of single-variable control by simultaneously integrating five types of operating parameters: screw operating parameters, traction operating parameters, product status parameters, temperature parameters, and pressure parameters, and through the systematic superposition of five adjustment quantities. It uses first-order difference to represent the rate of change and second-order difference to represent the trend of change, and combines this with sign comparison of the deviation direction to perform predictive adjustments at the initial stage of parameter change trends, elevating "post-event compensation" to "trend pre-control," effectively suppressing further expansion of deviations. A mechanism for determining and coordinating the temperature-pressure coupling direction is established. The coupling direction is determined by comparing the sign consistency of temperature and pressure deviations, and the output direction of the two adjustment quantities is determined differently based on the coupling direction. This effectively handles the strong coupling relationship between temperature and pressure, avoiding the mutual interference problems found in traditional independent control. Through a multi-level control architecture of screw operating trend prediction, real-time compensation for traction changes, product status deviation trigger correction, and temperature-pressure coupling coordination, this invention can effectively suppress various disturbances during cable extrusion and achieve precise and stable control of the screw speed. Attached Figure Description

[0063] Figure 1 A flowchart of an adaptive control method for the screw speed of a cable extruder is provided as an embodiment of this application;

[0064] Figure 2 A flowchart illustrating a method for superimposing screw speed adjustment amounts in a cable extruder, provided in an embodiment of this application;

[0065] Figure 3 This is a schematic diagram of an adaptive control system for the screw speed of a cable extruder, provided as an embodiment of this application. Detailed Implementation

[0066] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0067] See Figure 1 This is a flowchart of an adaptive control method for the screw speed of a cable extruder provided in this embodiment. The method includes steps S101 to S103, wherein:

[0068] S101: Obtain the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed;

[0069] S102: Generate a first speed adjustment amount based on the deviation direction of the screw operating parameters relative to their preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change;

[0070] A second speed adjustment is generated based on the change in the traction operating parameters;

[0071] The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation.

[0072] A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value.

[0073] S103: The first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount, and the fifth speed adjustment amount are superimposed on the current speed value to obtain the target speed value, and the screw is controlled to rotate using the target speed value.

[0074] In specific implementation, the cable extruder mainly includes a barrel, a screw rotatably installed inside the barrel, a drive device for driving the screw to rotate, a heating device installed on the barrel, a feed port and a discharge port installed on the barrel, and various sensors installed on the barrel. The sensors include at least a torque sensor for collecting screw load, an encoder for collecting traction speed, a laser diameter gauge for collecting product outer diameter, a temperature sensor for collecting melt temperature, and a pressure sensor for collecting die head pressure.

[0075] The system acquires various operating parameters in real time through the aforementioned sensors, and after calculation by adaptive control logic, outputs a speed command to the drive device to control the screw rotation.

[0076] Regarding step S101:

[0077] When the preset sampling period arrives, the operating parameters of the cable extruder are obtained respectively.

[0078] The preset sampling period is set as follows: the effective frequency band of the screw load signal is determined by the screw rotation frequency and its harmonics. The screw speed range of a conventional extruder is 2~35 rpm, and the effective energy of the load signal is concentrated within 5 Hz. According to Shannon's sampling theorem, the sampling frequency should be at least twice the highest frequency of the signal. While taking into account the accuracy requirements of digital filtering, the sampling period is set to 200 milliseconds, corresponding to a sampling frequency of 5 Hz.

[0079] In practical implementation, the screw operating parameter is the screw load. The screw load is the torque value that the screw bears during the rotary extrusion process. This torque value directly reflects the resistance state of the material inside the cable extruder barrel to the screw rotation.

[0080] When the sampling period arrives, the analog voltage amplitude characterizing the screw load is acquired, converted into a digital quantity, and the original measurement value at the current sampling time is obtained.

[0081] As an optional implementation, a five-point cubic smoothing filter is applied to the converted digital value. This is achieved by obtaining five values: the original measurement value at the second sampling time before the current sampling time, the original measurement value at the first sampling time before the current sampling time, the original measurement value at the first sampling time after the current sampling time, and the original measurement value at the second sampling time after the current sampling time. With the current sampling time as the zero point, the five sampling times are arranged at equal intervals on the time axis, with time offsets of negative two sampling periods, negative one sampling period, zero, positive one sampling period, and positive two sampling periods, respectively.

[0082] As an optional implementation, a five-point cubic smoothing filter is applied to the five values. A cubic curve is constructed to minimize the sum of squared errors between the values ​​at the five time offset positions and the corresponding five original measurements. After solving for the parameters of the cubic curve, the value at the zero point of the cubic curve is taken as the filtered output value at the current sampling time, and converted into the screw load value according to the sensor calibration relationship.

[0083] For example, with a sampling period of 200 milliseconds, assume that the measurement value of the second sampling point before the current sampling time is 2.480 volts, the measurement value of the first sampling point before that time is 2.490 volts, the measurement value of the current sampling point is 2.500 volts, the measurement value of the first sampling point after that time is 2.510 volts, and the measurement value of the second sampling point after that time is 2.505 volts.

[0084] The weighting coefficients for the five-point cubic smoothing filter are: 17 / 35 for the center point, 12 / 35 for each of the two points adjacent to the center point, and -3 / 35 for each of the two furthest points. Multiplying each of the five measurements by its corresponding weighting coefficient and summing the results yields the filtered output value: 2.480×(-3 / 35)+2.490×(12 / 35)+2.500×(17 / 35)+2.510×(12 / 35)+2.505×(-3 / 35)=2.501 volts.

[0085] Based on the sensor calibration relationship, for example, 1 volt corresponds to 40 Nm, 2.501 volts is converted to 100.04 Nm, which is used as the screw load value at the current moment.

[0086] In practice, the traction operating parameter is the traction speed, which is the linear speed of the traction cable core pulled by the traction device.

[0087] When the sampling period arrives, the pulse count value within the sampling period is acquired. The pulse count value is divided by the sampling period duration to obtain the pulse frequency per unit time. The pulse frequency is multiplied by the linear velocity constant to obtain the traction speed. The linear velocity constant is the ratio of the circumference of the traction wheel to the number of pulses per encoder revolution. In this embodiment, the linear velocity constant is 0.5 mm / pulse. The unit of traction speed is meters per minute.

[0088] In practical implementation, the product status parameter is the outer diameter of the cable; the temperature parameter is the melt temperature, which is the actual temperature of the material at the extruder outlet; and the pressure parameter is the die head pressure, which is the pressure value borne by the melt inside the die head, which can be obtained from the corresponding sensors.

[0089] Regarding step S102:

[0090] The first speed adjustment amount is generated based on the deviation direction of the screw operating parameters relative to their preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change.

[0091] In practical implementation, the preset screw operating target value refers to the expected value of the screw load, expressed in Newton-meters (Nm), as a percentage of the equipment's rated torque or a specific torque value. This value is obtained through calibration and remains constant within the same material production cycle. For example, in this embodiment, the screw load target value is 100.00 Nm.

[0092] Deviation direction refers to the sign of the difference between the current screw load value and the target screw load value. A positive difference indicates a positive deviation direction, a negative difference indicates a negative deviation direction, and a zero difference indicates no deviation.

[0093] Deviation refers to the absolute value of the difference between the current load value and the target value, measured in Newton-meters (Nm).

[0094] The numerical sequence of the screw operating parameters at multiple consecutive sampling times is obtained. The number of consecutive sampling times is determined based on the effective fluctuation period of the load signal and the minimum data volume required for trend analysis. In a conventional cable extruder under stable operating conditions, the screw load fluctuation period is approximately 5 to 10 seconds. If the sampling period is 200 milliseconds, a complete fluctuation period contains 25 to 50 sampling points. Therefore, the length of the numerical sequence is set to 60 sampling points for complete coverage.

[0095] The direction and degree of deviation of the screw operating parameters from the preset screw operating target value are calculated based on the numerical sequence.

[0096] A first-order difference sequence is calculated based on the numerical sequence, whereby the first-order difference sequence represents the rate of change. The first-order difference value for each adjacent moment is obtained by subtracting the value of the previous moment from the value of the next moment in the numerical sequence. This subtraction operation is performed on each adjacent moment in the numerical sequence to obtain the first-order difference sequence. Each value in the first-order difference sequence represents the instantaneous rate of load change at that moment, expressed in Newton-meters per second. The direction of the first-order difference sequence indicates the sign of the first-order difference value, where a positive value represents a load increase and a negative value represents a load decrease.

[0097] The second-order difference sequence is calculated based on the first-order difference sequence, which represents the trend of the rate of change. The second-order difference value is obtained by subtracting the first-order difference value of the previous moment from the first-order difference value of the next moment in the first-order difference sequence. This subtraction operation is performed on each adjacent moment in the first-order difference sequence to obtain the second-order difference sequence. Each value in the second-order difference sequence represents the instantaneous trend of the rate of change at that moment, i.e., the direction of acceleration. A positive second-order difference value indicates that the rate of increase of the load is accelerating or the rate of decrease is slowing down, while a negative value indicates that the rate of increase of the load is slowing down or the rate of decrease is accelerating.

[0098] The sign of the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are compared.

[0099] In practice, sign matching includes three scenarios: all three signs are the same, i.e., all are positive or all are negative; the deviation direction is inconsistent with the first-order difference direction; the deviation direction is opposite to the first-order difference direction and the first-order difference direction is opposite to the second-order difference direction.

[0100] The magnitude of the first speed adjustment is determined based on the symbol comparison results.

[0101] When the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are consistent, it is determined that the current deviation state is accelerating and deteriorating, and a stronger correction amount needs to be output to increase the amplitude of the first speed adjustment amount. The amplitude is positively correlated with the degree of deviation.

[0102] In practice, the amplitude of the first speed adjustment is calculated by multiplying the deviation degree by a first amplitude coefficient. The first amplitude coefficient is determined based on the response bandwidth of the control system and the safety limit of a single adjustment, and is set to one percent of the deviation degree. That is, amplitude = deviation degree × 1%. The direction of the first speed adjustment is opposite to the deviation direction.

[0103] When the deviation direction is inconsistent with the direction of the first-order difference sequence, it indicates that the screw load value is currently moving towards the target screw load value, meaning the deviation is converging. At this point, further subdivision based on the trend of the convergence speed is needed to determine whether to output a correction amount and, if so, by what magnitude.

[0104] In practice, if the deviation direction is inconsistent with the first-order difference direction, the first-order difference direction is further compared with the second-order difference direction.

[0105] Scenario 1: The deviation direction is inconsistent with the first-order difference direction, and the first-order difference direction is consistent with the second-order difference direction.

[0106] When the first-order difference direction coincides with the second-order difference direction, it indicates that the screw load value is returning to the target screw load value at an accelerating rate, and the deviation is converging rapidly. At this point, strong correction is unnecessary; only a weak auxiliary correction amount needs to be output to prevent overshoot during convergence. The amplitude of the first speed adjustment is equal to the deviation degree multiplied by the second amplitude coefficient. The second amplitude coefficient is taken as 0.5% of the deviation degree, i.e., amplitude = deviation degree × 0.5%. The direction of the first speed adjustment is opposite to the deviation direction.

[0107] Scenario 2: The deviation direction is inconsistent with the first-order difference direction, and the first-order difference direction is opposite to the second-order difference direction.

[0108] When the first-order difference direction is opposite to the second-order difference direction, it indicates that although the screw load value is still moving towards the target screw load value, the regression rate is decreasing, meaning the load curve is approaching a local extreme point, and the actual load trend in this region is uncertain. At this time, the amplitude of the first speed adjustment is set to zero, i.e., no first speed adjustment is output, to prevent erroneous adjustments in the uncertain direction range.

[0109] The first amplitude coefficient of 1% and the second amplitude coefficient of 0.5% are set according to the following: The first amplitude coefficient of 1% is based on conventional PID engineering tuning experience, and one percent of the deviation is used as the basic amplitude of proportional adjustment, which can take into account both response speed and stability; the second amplitude coefficient of 0.5% is reduced by half based on the first amplitude coefficient, and is used for weak correction in the trend convergence state to avoid excessive intervention in the natural convergence process.

[0110] The first speed adjustment amount determined by the above method is in Newton-meters (Nm). The amplitude is converted from Nm to speed (rpm) using a preset calibration proportionality coefficient. The calibration proportionality coefficient is set as follows: during calibration, the corresponding steady-state screw load is measured at multiple speed points to establish a speed-load correspondence. The conversion ratio is obtained by linear fitting using the least squares method. For example, in this embodiment, the calibration proportionality coefficient is 0.1 rpm·Nm.

[0111] For example, if the target screw load is 100.00 Nm, the load values ​​at three consecutive sampling times are 99.95 Nm at the previous time, 99.92 Nm at the previous time, and 99.88 Nm at the current time.

[0112] The deviation direction is negative, and the deviation degree is 0.12 Nm. The first-order difference direction is negative. The second-order difference direction is negative. Since the deviation direction, first-order difference direction, and second-order difference direction are all negative, the amplitude equals the deviation degree multiplied by one percent, i.e., 0.12 multiplied by one percent equals 0.0012 Nm. The direction is opposite to the deviation direction, i.e., positive, and the speed is increased. After conversion with a calibrated proportional coefficient of 0.1, the first speed adjustment is positive 0.00012 rpm.

[0113] If the current load value is 100.05 Nm, the previous load value was 100.20 Nm, and the load value before that was 100.25 Nm.

[0114] The deviation direction is positive, and the deviation degree is 0.05 Nm. The first-order difference direction is negative. The deviation direction is positive, and the first-order difference direction is negative; they are inconsistent. The first-order difference value at the previous moment was 100.20 minus 100.25, which equals -0.05; the second-order difference value was -0.15 minus -0.05, which equals -0.10; the second-order difference direction is negative. The first-order difference direction is negative, and the second-order difference direction is negative; they are consistent, belonging to case one. Therefore, the amplitude equals the deviation degree multiplied by five per thousand, that is, 0.05 multiplied by five per thousand equals 0.00025 Nm. The direction is opposite to the deviation direction, i.e., negative, so the speed is reduced. After conversion with a calibrated proportional coefficient of 0.1, the first speed adjustment is -0.000025 rpm.

[0115] A second speed adjustment is generated based on the change in the traction operating parameters.

[0116] In practice, the traction operating parameter is the traction speed. The traction speed will change during the acceleration and deceleration phase of the production line or when the take-up reel is changed. The change in traction speed will change the amount of extruded material per unit length of cable. If the screw speed is not adjusted accordingly, the outer diameter of the cable will deviate from the target value.

[0117] For example, the target traction speed value is obtained through calibration. The calibration method is as follows: traction speed values ​​are collected and arithmetically averaged under stable extruder operation. For example, in this embodiment, the target traction speed value is 30.00 meters per minute.

[0118] The system continuously acquires the first value of the traction operating parameter at the current moment and compares it with the second value of the traction operating parameter at the previous moment. When the absolute value of the comparison result is greater than a preset change threshold, it is determined that the traction operating parameter has changed, and the current moment is recorded as the start moment. The preset change threshold is set according to the speed control accuracy of the traction system, and is typically taken as 0.5% to 1% of the target traction speed value. For example, the preset change threshold can be set to eight per thousand of the target traction speed value.

[0119] The change in the traction operating parameter is determined based on the difference between the first value and the second value. The change is the difference between the traction speed at the current moment and the traction speed at the previous moment, and the unit is meters per minute.

[0120] The speed compensation is calculated based on the change and the conveying characteristic parameters of the cable extruder. The conveying characteristic parameters include at least the geometric parameters of the screw. These parameters refer to the inherent equipment parameters used to calculate unit output, including the screw diameter and pitch, in millimeters. For example, in this embodiment, the screw diameter and pitch are both 90 millimeters.

[0121] Obtain the current rotational speed value, and determine the first unit output based on the current rotational speed value, the first value, and the conveying characteristic parameters.

[0122] In practical implementation, the theoretical conveying volume per revolution of the screw is calculated based on the screw diameter and pitch. The theoretical conveying volume is equal to the cross-sectional area of ​​the screw multiplied by the pitch, where the cross-sectional area of ​​the screw is calculated from the screw diameter. The current rotational speed is multiplied by the theoretical conveying volume to obtain the theoretical conveying volume per unit time. The theoretical conveying volume per unit time is divided by the first value of the traction speed at the current moment to obtain the conveying volume corresponding to the unit length, i.e., the first unit output.

[0123] Similarly, the second unit output is determined based on the current rotational speed, the second value, and the conveying characteristic parameters.

[0124] Based on the ratio of the first unit output to the second unit output, the current rotation speed value is multiplied by the ratio to obtain the target rotation speed value that restores the unit output to the first unit output.

[0125] The difference between the target speed value and the current speed value is used as the speed compensation amount.

[0126] The speed compensation amount is used as the second speed adjustment amount, and the second speed adjustment amount is superimposed on the target speed value during the first control cycle after the start time.

[0127] In practice, the target traction speed is 30.00 meters per minute, and the preset change threshold is 0.24 meters per minute. Assuming the current traction speed is 30.10 meters per minute and the previous traction speed was 29.80 meters per minute, the absolute value of the difference is 0.30 meters per minute, which is greater than the preset change threshold of 0.24 meters per minute. Therefore, a significant change in traction speed is determined, and the current moment is recorded as the starting moment. The change in traction speed is positive 0.30 meters per minute.

[0128] The current rotational speed is 15.0 revolutions per minute. The screw diameter is 90 mm, and the pitch is 90 mm. The theoretical conveying volume is 572,265 cubic millimeters.

[0129] First unit output: Multiply the current rotation speed of 15.0 revolutions per minute by the theoretical conveying volume of 572,265 cubic millimeters, and get a theoretical conveying volume of 8,583,975 cubic millimeters per minute. Divide this by the current traction speed of 30.10 meters per minute, and get 285,200 cubic millimeters per meter.

[0130] Second unit output: Multiply the current rotation speed of 15.0 revolutions per minute by the theoretical conveying volume of 572,265 cubic millimeters, and get a theoretical conveying volume of 8,583,975 cubic millimeters per minute. Divide this by the previous moment's traction speed of 29.80 meters per minute, and get 288,000 cubic millimeters per meter.

[0131] The ratio of the first unit output to the second unit output is 0.9903. Multiplying the current speed of 15.0 rpm by 0.9903 yields a target speed of 14.8545 rpm. The difference between the target speed and the current speed is -0.1455 rpm, meaning the speed compensation is -0.1455 rpm. Therefore, the second speed adjustment is also -0.1455 rpm.

[0132] The product status parameters are compared with their preset product status target values ​​to determine the product status deviation. When the product status deviation meets the preset triggering conditions, a third speed adjustment amount is generated based on the product status deviation.

[0133] In practical implementation, the product status parameter refers to the cable outer diameter, measured in millimeters. Besides the cable outer diameter, other product status parameters in other implementations may include cable wall thickness, cable capacitance, or cable eccentricity.

[0134] The preset product status target value refers to the expected value of the cable's outer diameter, in millimeters, and is set according to the process specifications of the cable product to be manufactured. For example, in this embodiment, the target value of the cable's outer diameter can be 10.00 millimeters.

[0135] The product status deviation is the difference between the product status parameter and the preset product status target value.

[0136] Record the starting time when the product state deviation exceeds the deviation range, and start timing from the starting time to obtain the duration during which the product state deviation continuously exceeds the deviation range;

[0137] The preset trigger condition is that the product status deviation exceeds the preset deviation range, and the duration for which the product status deviation continuously exceeds the preset deviation range reaches a preset duration threshold.

[0138] The preset deviation range refers to the upper and lower limits of the allowable fluctuation of the cable's outer diameter, set according to the tolerance standards of the cable product. The lower and upper limits of the preset deviation range constitute a dead zone. When the outer diameter deviation is within this zone, the system considers the current product status to be within acceptable limits and does not trigger the generation of the third speed adjustment. For example, in this embodiment, the preset deviation range is ±0.20 mm, and the dead zone is the range from -0.20 mm to ±0.20 mm.

[0139] A preset duration threshold, measured in seconds, is used to determine whether the outer diameter deviation persists, and is used to further filter out transient interference. For example, in this embodiment, the preset duration threshold is 2 seconds.

[0140] If the triggering conditions are not met, the third speed adjustment amount will not be generated.

[0141] The third speed adjustment amount is generated based on the product state deviation, including:

[0142] Using the boundary value of the deviation range, i.e., the dead zone boundary, as the starting boundary, multiple deviation intervals are sequentially divided along the direction of increasing outer diameter deviation, with each interval having an equal width. The sign of the deviation determines the direction: positive deviations enter the positive interval sequence, and negative deviations enter the negative interval sequence. The interval width is set based on the matching relationship between the resolution and control accuracy of the measurement system. For example, in this embodiment, the deviation interval width is 0.10 mm.

[0143] The absolute value of the outer diameter deviation is compared sequentially with the interval boundary value to determine the interval number it falls into. Specifically, the absolute value of the outer diameter deviation is subtracted from the dead zone boundary value to obtain the portion exceeding the dead zone; this excess portion is divided by the interval width, and the result is rounded up to obtain the interval number. Interval numbers start from 1.

[0144] As an optional implementation, a target deviation range into which the product state deviation falls is determined, and the adjustment gain corresponding to the target deviation range is determined by a segmented gain control algorithm as the preset gain control algorithm.

[0145] In practical implementation, the deviation intervals are arranged in ascending order of their serial numbers, and the gain value increases with the interval number. The specific allocation method for the gain value is as follows: a base gain and a gain increment step size are set. The gain of the Nth interval is equal to the base gain plus N-1 times the increment step size. A maximum gain upper limit is also set; when the calculated value exceeds the upper limit, the upper limit value is used. The setting of the base gain, increment step size, and maximum gain upper limit is based on the response characteristics of the control system and product quality requirements: the base gain ensures the minimum correction force for small deviations, the increment step size ensures a smooth transition of gain in each interval as the deviation increases, and the maximum gain upper limit prevents the single adjustment amount from exceeding the safety limit when the deviation is too large. For example, in this embodiment, the base gain is 5%, the increment step size is 5%, and the maximum gain upper limit is 30%.

[0146] The third speed adjustment amount is obtained by multiplying the adjustment gain corresponding to the target deviation range by the product state deviation amount, and then dividing the result by the calibration conversion ratio. The unit is revolutions per minute (rpm). In this embodiment, the calibration conversion ratio can be 0.02 mm per revolution per minute.

[0147] The direction of the third speed adjustment is opposite to the direction of the deviation: when the outer diameter is too large, a negative adjustment is output, and when the outer diameter is too small, a positive adjustment is output.

[0148] In practical implementation, the target outer diameter is 10.00 mm, the preset deviation range is ±0.20 mm, and the dead zone is from -0.20 mm to ±0.20 mm. The preset duration threshold is 2 seconds. The deviation interval width is 0.10 mm. The base gain is 5%, the increment step size is 5%, and the maximum gain is 30%. Therefore, the gain for the first interval is 5%, the gain for the second interval is 10%, the gain for the third interval is 15%, the gain for the fourth interval and above is 20%, and so on up to the maximum gain of 30%.

[0149] Assuming the current outer diameter is 10.35 mm, the outer diameter deviation is +0.35 mm. If the absolute value of the deviation (0.35 mm) is greater than the dead zone boundary (0.20 mm), record the start time of the over-limit and begin timing. If the outer diameter is still 10.35 mm after 2 seconds, the trigger condition is met.

[0150] The deviation exceeding the dead zone is 0.35 mm minus 0.20 mm, equaling 0.15 mm. Dividing the excess 0.15 mm by the interval width of 0.10 mm equals 1.5, rounding up to 2, which falls into the second interval. The gain of the second interval is 5% plus (2 minus 1) multiplied by 5%, equaling 10%. The initial third speed adjustment is 0.35 mm multiplied by 10%, equaling 0.035 mm. The calibrated conversion ratio is 0.02 mm per revolution per minute. The third speed adjustment is 0.035 divided by 0.02, equaling 1.75 revolutions per minute. The outer diameter is too large, and the direction is negative; the third speed adjustment is -1.75 revolutions per minute.

[0151] A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value.

[0152] In specific implementations, the temperature parameter refers to the melt temperature, measured in degrees Celsius, which is the actual temperature of the material at the extruder outlet. In other embodiments, the temperature parameter may also include the temperature values ​​of multiple heating sections of the barrel, such as the feed section temperature, compression section temperature, and metering section temperature. The pressure parameter refers to the die head pressure, measured in megapascals (MPa), which is the pressure value borne by the melt inside the die head. In other embodiments, the pressure parameter may also include the pressure difference before and after the filter screen, and the pressure values ​​at different axial positions inside the barrel.

[0153] The preset temperature target value refers to the expected melt temperature, in degrees Celsius, determined based on the recommended processing temperature range of the material to be processed. For example, in this embodiment, the melt temperature target value is 200 degrees Celsius. The preset pressure target value refers to the expected die head pressure, in megapascals (MPa), determined based on the design rated pressure of the extruder die head and the rheological characteristics of the material. For example, in this embodiment, the die head pressure target value is 15.00 MPa.

[0154] The temperature deviation and the pressure deviation are obtained, and the first sign of the temperature deviation and the second sign of the pressure deviation are compared to determine the coupling direction between the temperature deviation and the pressure deviation; and the output direction of the fourth speed adjustment and the fifth speed adjustment is determined according to the coupling direction.

[0155] When the first symbol and the second symbol are identical, it is determined to be co-directional coupling. Co-directional coupling indicates that temperature and pressure show a synchronous trend of change. Its physical meaning is that the fluctuation of the overall average molecular weight of the material or the overall change of the plasticization state leads to the co-directional change of temperature and pressure. At this time, the direction of the fourth speed adjustment is opposite to the direction of the temperature deviation, that is, the speed is reduced when the temperature is too high and the speed is increased when the temperature is too low. The direction of the fifth speed adjustment is opposite to the direction of the pressure deviation, that is, the speed is reduced when the pressure is too high and the speed is increased when the pressure is too low.

[0156] When the first symbol and the second symbol are inconsistent, it is determined to be reverse coupling. Reverse coupling indicates that temperature and pressure show opposite trends. Its physical meaning is that factors such as changes in the content of low molecular weight components in the material or partial blockage of the filter screen cause temperature and pressure to change in opposite directions. Further calculation of the ratio between the absolute value of temperature deviation and the absolute value of pressure deviation is used as the coupling degree coefficient. When the coupling degree coefficient is greater than 1, temperature deviation is the dominant factor, and the direction of temperature deviation is used as the common direction of the fourth and fifth speed adjustment amounts; when the coupling degree coefficient is less than 1, pressure deviation is the dominant factor, and the direction of pressure deviation is used as the common direction; when the coupling degree coefficient is equal to 1, the direction of temperature deviation is used as the common direction.

[0157] The magnitude of the fourth speed adjustment is positively correlated with the absolute value of the temperature deviation, and the magnitude of the fifth speed adjustment is positively correlated with the absolute value of the pressure deviation.

[0158] As an optional implementation method, the amplitudes of the fourth and fifth speed adjustment amounts can be determined using a proportional control method. Specifically, the amplitude of the fourth speed adjustment amount is obtained by multiplying the absolute value of the temperature deviation by a temperature deviation proportional coefficient, in revolutions per minute (rpm); the amplitude of the fifth speed adjustment amount is obtained by multiplying the absolute value of the pressure deviation by a pressure deviation proportional coefficient, in revolutions per minute (rpm).

[0159] The temperature deviation proportional coefficient is set based on the rotational speed compensation amount corresponding to each degree Celsius change in temperature deviation, which is determined according to the sensitivity of temperature to the melt viscosity and extrusion flow rate.

[0160] Specifically, the temperature deviation is directly proportional to the screw speed adjustment. When the temperature is too high, the melt viscosity decreases, the fluidity increases, and the extrusion rate per unit time increases, requiring a reduction in screw speed to maintain a constant extrusion rate; when the temperature is too low, the speed needs to be increased. The temperature deviation proportionality coefficient is the speed compensation amount corresponding to a unit temperature deviation.

[0161] The pressure deviation proportional coefficient is set based on the speed compensation amount corresponding to each change of one MPa in pressure deviation, which is determined according to the sensitivity of pressure to extrusion flow rate.

[0162] Specifically, the pressure deviation is directly proportional to the screw speed adjustment. When the pressure is too high, the melt flow resistance increases, and the extrusion volume per unit time decreases, requiring an increase in screw speed to compensate for the decrease in extrusion volume; when the pressure is too low, the speed needs to be reduced. The proportionality coefficient is the speed compensation amount corresponding to a unit pressure deviation.

[0163] The temperature deviation proportionality factor is greater than the pressure deviation proportionality factor, and it is set based on the fact that melt temperature has a more direct and significant impact on product quality than pressure. For example, in this embodiment, the temperature deviation proportionality factor is set to 0.5 revolutions per minute per degree Celsius, and the pressure deviation proportionality factor is set to 0.3 revolutions per minute per megapascal.

[0164] For example, the target melt temperature is 200 degrees Celsius, the current melt temperature is 202 degrees Celsius, and the temperature deviation is +2 degrees Celsius, with the first sign being positive. The target die head pressure is 15.00 MPa, the current die head pressure is 15.80 MPa, and the pressure deviation is +0.80 MPa, with the second sign being positive. Since both the first and second signs are positive, it is determined to be coupled in the same direction.

[0165] The magnitude of the fourth speed adjustment is 2 degrees Celsius multiplied by 0.5 revolutions per minute per degree Celsius, which equals 1.0 revolutions per minute. The magnitude of the fifth speed adjustment is 0.80 MPa multiplied by 0.3 revolutions per minute per MPa, which equals 0.24 revolutions per minute. Under unidirectional coupling, the directions of both adjustments are opposite to their respective deviation directions: the fourth speed adjustment is -1.0 revolutions per minute, and the fifth speed adjustment is -0.24 revolutions per minute.

[0166] Regarding step S103:

[0167] The first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount, and the fifth speed adjustment amount are superimposed on the current speed value to obtain the target speed value, and the screw rotation is controlled by the target speed value.

[0168] The current speed value is used as the initial reference value, and the first speed adjustment, the second speed adjustment, the third speed adjustment, the fourth speed adjustment and the fifth speed adjustment are sequentially superimposed on the initial reference value through a preset superposition strategy to obtain the speed value to be used.

[0169] As an optional implementation, a weighted priority stacking strategy is adopted, with priorities from highest to lowest as follows: second speed adjustment amount, third speed adjustment amount, fourth speed adjustment amount, fifth speed adjustment amount, and first speed adjustment amount. The priority ranking is based on the timeliness requirements of each adjustment amount: the second adjustment amount corresponds to the immediate change in traction speed and needs to be compensated within the first control cycle, thus having the highest timeliness; the third adjustment amount involves product quality and needs continuous correction until the deviation is eliminated; the fourth and fifth adjustment amounts involve the transition process of temperature and pressure; the first adjustment amount is based on trend prediction and allows for a moderate delay.

[0170] The safe speed range refers to the upper and lower limits of the screw's permissible operating speed. The lower limit is the minimum speed required for the screw to start and run, and the upper limit is 90% of the screw's maximum permissible design speed. The lower limit is set to ensure that the screw can build up sufficient extrusion pressure, and the upper limit is set to leave a safety margin to prevent overload of the drive system.

[0171] See Figure 2 The flowchart of a method for superimposing screw speed adjustment of a cable extruder according to an embodiment of this application includes:

[0172] In practice, the current speed value is used as the initial reference value, and this reference value is assigned to the intermediate speed value. Adjustments are retrieved sequentially from high to low priority and then superimposed. The superposition operation for each adjustment includes the following judgments and calculations:

[0173] First, calculate the accumulated adjustment amount, which is the current intermediate speed value minus the initial reference value. Then, calculate the adjustable margin, which is the preset maximum adjustment amplitude minus the absolute value of the accumulated adjustment amount. The preset maximum adjustment amplitude refers to the maximum speed change allowed to accumulate within a single control cycle, measured in revolutions per minute (rpm). This value is set based on the instantaneous response capability of the drive system, i.e., the maximum speed change that the drive system can withstand within a single control cycle when adjusting from one steady-state speed to another. For example, it can be taken as 5.0 rpm.

[0174] The absolute value of the current adjustment amount to be superimposed is compared with the adjustable margin: if the absolute value of the adjustment amount to be superimposed is less than or equal to the adjustable margin, the original amplitude of the adjustment amount is retained; if the absolute value of the adjustment amount to be superimposed is greater than the adjustable margin, the amplitude of the adjustment amount is changed to the value of the adjustable margin, while the direction remains consistent with the original adjustment amount. The adjustment amount processed as described above is superimposed on the intermediate speed value, and the intermediate speed value is updated. The above operation is repeated until all five adjustment amounts have been processed, and the speed value to be used is obtained.

[0175] A safety check is performed on the speed value to be used. The speed value to be used is compared with a preset safe speed range. When the speed value to be used exceeds the safe speed range, the speed value to be used is corrected to the boundary value of the safe speed range or the current speed value is kept unchanged, and a limiting prompt signal is generated.

[0176] When the speed to be used is within the safe speed range, the speed to be used is taken as the target speed.

[0177] Based on the same inventive concept, this application also provides a cable extruder screw speed adaptive control system for the cable extruder screw speed adaptive control method.

[0178] See Figure 3 The diagram shown is a schematic of an adaptive control system for the screw speed of a cable extruder according to an embodiment of this application. The system includes an acquisition module 10, a generation module 20, and an output module 30, wherein:

[0179] Acquisition module 10: used to acquire the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed;

[0180] Generation module 20: is used to generate a first speed adjustment amount based on the deviation direction of the screw operating parameters relative to their preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change;

[0181] A second speed adjustment is generated based on the change in the traction operating parameters;

[0182] The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation.

[0183] A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value.

[0184] Output module 30: is used to superimpose the first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount and the fifth speed adjustment amount to the current speed value to obtain a target speed value, and control the screw rotation with the target speed value.

[0185] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0186] In the description of this specification, the terms "exemplary," "for example," "specifically," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A method for adaptive control of screw speed in a cable extruder, characterized in that, The method includes: Obtain the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed; The first speed adjustment amount is generated based on the deviation direction of the screw operating parameters relative to their preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change. A second speed adjustment is generated based on the change in the traction operating parameters; The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation. A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value. The first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount, and the fifth speed adjustment amount are superimposed on the current speed value to obtain the target speed value, and the screw rotation is controlled by the target speed value.

2. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The step of generating the first speed adjustment amount based on the screw operating parameters includes: Obtain the numerical sequence of the screw operating parameters at multiple consecutive sampling times; The direction and degree of deviation of the screw operating parameters from the preset screw operating target value are calculated based on the numerical sequence. Calculate a first-order difference sequence based on the numerical sequence, wherein the first-order difference sequence characterizes the rate of change; The second-order difference sequence is calculated based on the first-order difference sequence, and the second-order difference sequence represents the trend of the rate of change. The sign of the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are compared. The magnitude of the first speed adjustment is determined based on the symbol comparison results.

3. The adaptive control method for the screw speed of a cable extruder according to claim 2, characterized in that, Determining the magnitude of the first speed adjustment based on the symbol comparison result includes: When the deviation direction, the direction of the first-order difference sequence, and the direction of the second-order difference sequence are consistent, the amplitude of the first speed adjustment is increased, and the amplitude is positively correlated with the degree of deviation. When the deviation direction is inconsistent with the direction of the first-order difference sequence, the amplitude of the first speed adjustment is reduced, and the amplitude is negatively correlated with the degree of deviation.

4. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The process of generating the second speed adjustment amount based on the changes in traction operating parameters includes: The system continuously acquires the first value of the traction operation parameter at the current moment and compares it with the second value of the traction operation parameter at the previous moment. When the absolute value of the comparison result is greater than a preset change threshold, it determines that the traction operation parameter has changed value and records the current moment as the start moment. The change in the traction operation parameter is determined based on the difference between the first value and the second value; The speed compensation is calculated based on the change and the conveying characteristic parameters of the cable extruder, wherein the conveying characteristic parameters include at least the geometric parameters of the screw. The speed compensation amount is used as the second speed adjustment amount, and the second speed adjustment amount is superimposed on the target speed value during the first control cycle after the start time.

5. The adaptive control method for screw speed of a cable extruder according to claim 4, characterized in that, The calculation of the speed compensation amount based on the change and the conveying characteristic parameters of the cable extruder includes: Get the current rotational speed value; The first unit output is determined based on the current rotation speed, the first value, and the conveying characteristic parameters. The second unit output is determined based on the current rotational speed, the second value, and the conveying characteristic parameters. Based on the ratio of the first unit output to the second unit output, determine the target rotational speed value corresponding to restoring the unit output to the first unit output; The difference between the target speed value and the current speed value is used as the speed compensation amount.

6. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The continuously satisfied preset triggering conditions include: The preset trigger condition is that the product state deviation exceeds the preset deviation range, and the duration for which the product state deviation continuously exceeds the preset deviation range reaches a preset duration threshold. The product status deviation is the difference between the product status parameter and the preset product status target value; Record the starting time when the product state deviation exceeds the deviation range, and start timing from the starting time to obtain the duration for which the product state deviation continuously exceeds the preset deviation range; If the triggering conditions are not met, the third speed adjustment amount will not be generated.

7. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The third speed adjustment amount is generated based on the product state deviation, including: Multiple deviation intervals are set, and each deviation interval is arranged in order of increasing product state deviation, with each deviation interval having the same width. The target deviation range into which the product state deviation falls is determined, and the adjustment gain corresponding to the target deviation range is determined by a preset gain control algorithm. The third speed adjustment amount is obtained by multiplying the adjustment gain corresponding to the target deviation range by the product state deviation amount.

8. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The process of generating the fourth and fifth speed adjustment values ​​based on temperature and pressure parameters includes: The temperature deviation and the pressure deviation are obtained, and the first sign of the temperature deviation and the second sign of the pressure deviation are compared to determine the coupling direction between the temperature deviation and the pressure deviation. The output directions of the fourth speed adjustment amount and the fifth speed adjustment amount are determined based on the coupling direction.

9. The adaptive control method for screw speed of a cable extruder according to claim 8, characterized in that, Determining the output directions of the fourth speed adjustment amount and the fifth speed adjustment amount based on the coupling direction includes: When the first symbol is the same as the second symbol, the direction of the fourth speed adjustment amount is opposite to the direction of the temperature deviation amount, and the direction of the fifth speed adjustment amount is opposite to the direction of the pressure deviation amount; When the first symbol and the second symbol are inconsistent, the direction of the larger of the temperature deviation and the pressure deviation shall be taken as the common direction of the fourth speed adjustment and the fifth speed adjustment. The magnitude of the fourth speed adjustment is positively correlated with the absolute value of the temperature deviation, and the magnitude of the fifth speed adjustment is positively correlated with the absolute value of the pressure deviation.

10. The adaptive control method for screw speed of a cable extruder according to claim 1, characterized in that, The obtained target rotational speed value includes: The current speed value is used as the initial reference value, and the first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount and the fifth speed adjustment amount are sequentially superimposed on the initial reference value through a preset superposition strategy to obtain the speed value to be used, and the speed value to be used is subjected to a safety verification.

11. The adaptive control method for screw speed of a cable extruder according to claim 10, characterized in that, The safety verification of the rotation speed value to be used includes: The speed value to be used is compared with the preset safe speed range. When the speed value to be used exceeds the safe speed range, the speed value to be used is corrected to the boundary value of the safe speed range or the current speed value is kept unchanged, and a limiting prompt signal is generated. When the speed to be used is within the safe speed range, the speed to be used is taken as the target speed.

12. A screw speed adaptive control system for a cable extruder, used to implement the screw speed adaptive control method for a cable extruder as described in any one of claims 1-11, characterized in that, The system includes: an acquisition module, a generation module, and an output module, wherein: Acquisition module: used to acquire the operating parameters of the cable extruder, including screw operating parameters, traction operating parameters, product status parameters, temperature parameters, pressure parameters, and current rotational speed; The generation module is used to generate a first speed adjustment amount based on the direction of deviation of the screw operating parameters from its preset screw operating target value, the rate of change of the deviation degree over time, and the trend of the rate of change. A second speed adjustment is generated based on the change in the traction operating parameters; The product status parameters are compared with their preset product status target values ​​and the product status deviation is determined. When the product status deviation continuously meets the preset triggering conditions, a third speed adjustment is generated based on the product status deviation. A fourth speed adjustment amount is generated based on the temperature deviation between the temperature parameter and its preset temperature target value, and a fifth speed adjustment amount is generated based on the pressure deviation between the pressure parameter and its preset pressure target value. Output module: used to superimpose the first speed adjustment amount, the second speed adjustment amount, the third speed adjustment amount, the fourth speed adjustment amount and the fifth speed adjustment amount to the current speed value to obtain the target speed value, and control the screw rotation with the target speed value.

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