A method for controlling the taper of a protective film winding tension

Abstract

The application provides a taper control method for winding tension of a protective film, and relates to the technical field of industrial automation control. The method determines a next layer stress deviation prediction quantity by obtaining a film roll stress state, a radius state and a material elasticity state, dynamically corrects a reference taper curve according to the prediction quantity and a historical stress deviation state, and outputs an execution after compensating a target tension according to a current tension execution state. The method introduces a film roll internal stress evolution law and material elasticity temperature drift characteristics into a closed-loop correction process of a tension setting value, so that the taper curve has self-adaptive adjustment capability for film roll radius change, material batch difference, environmental temperature drift and winding speed fluctuation. The method fundamentally solves the problem of coexistence of inner layer crushing and outer layer relaxation caused by a preset fixed curve failing to respond to working condition changes, and realizes dynamic balance of full layer stress distribution.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control technology, and more specifically, to a method for taper control of the winding tension of a protective film. Background Technology

[0002] In industries involving winding processes, such as film manufacturing, printing and packaging, and precision coating, the quality of the winding process directly determines the yield and service performance of the final product. Protective film, as a surface protection material, requires continuous film material to be wound layer by layer onto a roller core to form a roll. As the roll diameter increases layer by layer from the empty roller core, the stress state of each layer exhibits a non-linear distribution with radial position. If the winding tension of each layer is constant, the inner layer, due to its smaller winding radius, will experience significantly higher compressive stress than the outer layer. This interlayer stress accumulation effect can lead to plastic crushing or wrinkling of the inner layer material, while the outer layer, due to insufficient tension, will loosen and slip, ultimately rendering the entire roll of film unusable. To suppress this layering effect, existing technologies widely employ a tapered tension control strategy. This involves gradually decreasing the tension layer by layer during the winding process as the roll radius increases, according to a preset rule, to balance the stress distribution across each layer. Several technical approaches have emerged around this strategy: one is open-loop taper control based on roll diameter detection, which obtains the real-time roll diameter through ultrasonic sensors, encoders, etc., calculates the target tension based on a linear or nonlinear taper curve, and outputs it to the actuator; another approach introduces a tension sensor to form a closed-loop feedback, using PID control to adjust the tension deviation; in recent years, research has also applied intelligent algorithms such as fuzzy neural networks and active disturbance rejection control to taper tension control in order to improve control accuracy and adaptability. These technologies have improved winding quality to some extent, forming the technical background of this invention.

[0003] However, existing taper tension control technologies still face several unresolved technical shortcomings. Firstly, the taper curves of existing methods are mostly fixed curves preset before winding starts based on roller core radius, full roll radius, and empirical material parameters. These cannot be dynamically adjusted according to the evolution of the actual stress state inside the film roll during winding. When winding speed fluctuates, material batches differ, or environmental temperature and humidity change, a systematic deviation will occur between the target stress distribution corresponding to the preset curve and the actual stress distribution inside the film roll. This deviation lacks an effective correction mechanism in existing open-loop or conventional closed-loop structures. Secondly, protective film materials are mostly high-molecular polymers, whose elastic modulus is highly sensitive to changes in environmental temperature. Existing taper control methods typically calculate the tension setpoint based on a fixed modulus at room temperature, failing to incorporate material stiffness changes caused by temperature drift into the control decision, further exacerbating the stress distribution mismatch. Third, existing tension feedback control mainly focuses on the instantaneous stability of the membrane surface tension, lacking the ability to perceive and regulate the cumulative stress state of each layer within the membrane roll. Therefore, it is difficult to fundamentally resolve the essential contradiction of inner layer crushing and outer layer relaxation coexisting. To address the above problems, this invention provides a taper control method for protecting the membrane winding tension. By acquiring the membrane roll stress state, membrane roll radius state, and material elasticity state during the winding process, the predicted stress deviation for the next layer is determined. Then, based on this predicted value and historical stress deviation states, the reference taper curve is dynamically corrected, and the target tension is compensated according to the current tension execution state before outputting the execution. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a tapered control method for the winding tension of a protective film. This method addresses, to some extent, the issues arising during the protective film winding process, such as the real-time changes in the winding roller speed and film roll radius, the drift of the elastic modulus of the protective film material with ambient temperature, and the deviation of the actual stress distribution of each layer from the target equilibrium state when tension is applied according to a preset fixed tapered curve. This results in the coexistence of inner layer crushing and outer layer relaxation, making it impossible to achieve a balanced stress distribution across the entire layer.

[0005] According to one aspect of the present invention, a method for taper control of the winding tension of a protective film is provided, comprising:

[0006] The stress state, radius state, and elastic state of the material of the protective film during the winding process are obtained, and the stress deviation prediction amount corresponding to the next layer of winding is determined based on the stress state, radius state, and elastic state of the material.

[0007] Based on the predicted stress deviation and the historical stress deviation, the reference taper curve is corrected to obtain the corrected taper curve.

[0008] The target tension is determined based on the corrected taper curve, and the target tension is compensated according to the current tension execution state to obtain the compensated tension command;

[0009] The winding drive system is controlled to perform winding tension control according to the compensated tension command.

[0010] Furthermore, the stress state of the membrane roll is characterized by the cumulative stress distribution of the wound macrolayer. The wound macrolayer is formed by merging multiple continuous physical membrane layers according to the radial position of the membrane roll, and each wound macrolayer corresponds to a continuous thickness range in the radial direction of the membrane roll. The cumulative stress distribution is characterized by a membrane roll macrolayer state table, which includes macrolayer number, macrolayer starting radius, macrolayer ending radius, macrolayer representative radius, macrolayer equivalent thickness, macrolayer average winding tension, macrolayer average winding temperature, macrolayer elastic modulus at winding time, current cumulative equivalent stress, current target equivalent stress, and historical stress integral value.

[0011] Furthermore, the determination of the stress deviation prediction for the next layer of winding is based on the film roll stress state, film roll radius state, and material elastic state, combined with the stress transmission depth obtained through online identification, to predict the stress increment generated by the next layer of winding on each already wound macrolayer, and the normalized difference between the predicted value and the target stress increment that varies with the film roll radius and elastic modulus is used as the stress deviation prediction.

[0012] Furthermore, the reference taper curve is corrected to obtain the corrected taper curve, which includes:

[0013] The stress deviation prediction values ​​of each macro layer are weighted and summed to obtain the comprehensive stress deviation prediction value. The historical stress integral values ​​of each macro layer are weighted and summed to obtain the comprehensive historical stress integral value.

[0014] The winding controller calculates the taper correction factor based on the predicted comprehensive stress deviation and the comprehensive historical stress integral value, and calculates the slope correction amount based on the current tension execution deviation.

[0015] Calculate the slope of the corrected taper curve within the next winding interval using the following formula:

[0016]

[0017] in, To correct the slope of the tapered curve in the next winding interval, This is the taper correction factor. The slope of the reference taper curve within the next winding interval. This is a dimensionless, constrained expression for the current tension execution deviation. To protect the effective width of the membrane, As a reference for stress normalization, The dimensionless stress slope coupling coefficient, projection operator This means that the calculation results will be restricted to the operating boundary corresponding to the current radius.

[0018] Further, compensating the target tension based on the current tension execution state includes:

[0019] Under stable winding conditions, the winding controller estimates the current tension by measuring motor current, angular velocity, angular acceleration, and non-negative radius growth rate. Under unstable winding conditions, it switches to the tension sensor or floating roller feedback to obtain the current tension.

[0020] The non-negative radius growth rate The in-wound film length and effective layer thickness are calculated using the following formula:

[0021]

[0022] in, For the current effective layer thickness, Given the current linear velocity of the protective film, This represents the current membrane roll radius.

[0023] Furthermore, compensating for the target tension based on the current tension execution state also includes:

[0024] The take-up controller uses the difference between the target tension and the current tension as the tension execution deviation, and calculates the compensation gain according to the following formula. :

[0025]

[0026] in, This is the normalized position of the current membrane roll radius. and The coefficient is a dimensionless compensation coefficient. This represents the equivalent moment of inertia of the current film roll and winding shaft. The non-negative growth rate of rotational inertia caused by the entrained material. The angular acceleration of the take-up roller. The angular velocity of the take-up roller, As the reference quantity for tension normalization, This represents the upper boundary of the compensation gain corresponding to the current radius.

[0027] The winding controller applies the compensation gain to the tension execution deviation to obtain the compensation amount, and then superimposes the target tension with the compensation amount to obtain the compensated tension command.

[0028] Further, controlling the winding drive system to perform winding tension control according to the compensated tension command includes:

[0029] Based on the current film roll radius and production line speed, the winding roller speed control value is generated in coordination, so that the winding roller speed adjustment is synchronized with the tension applied by the tension actuator.

[0030] When the stress deviates from the predicted amount and exceeds the recoverable operating range, the winding controller enters a protective control state and uses a hysteresis state machine to manage the stress protection flag.

[0031] The setting boundary of the stress protection mark is higher than the release boundary. When the dimensionless stress deviation of the macrolayer enters the setting boundary, it is used as the setting condition. After falling back to the release boundary and continuously maintaining it for several macrolayers, it is used as the release condition.

[0032] Once in protection mode, the controller performs one or more of the following protective operations: reducing the winding speed, limiting the rate of change of tension command, maintaining a slow transition of the current tension command, prioritizing the use of tension sensor or floating roller feedback closed loop, and outputting a stress deviation warning to the host computer.

[0033] According to another aspect of the present invention, a taper control system for protecting the winding tension of a film is provided, comprising:

[0034] The data sensing and prediction module is used to acquire the film roll stress state, film roll radius state and material elastic state during the protective film winding process, and to determine the stress deviation prediction amount corresponding to the next layer winding based on the film roll stress state, film roll radius state and material elastic state.

[0035] The taper curve correction module is used to correct the reference taper curve based on the predicted stress deviation and the historical stress deviation state, so as to obtain the corrected taper curve.

[0036] The tension compensation module is used to determine the target tension based on the corrected taper curve, and to compensate the target tension according to the current tension execution state to obtain the compensated tension command.

[0037] The execution and protection module is used to control the winding drive system to perform winding tension control according to the compensated tension command.

[0038] Compared with existing technologies, the tapered control method for protective film winding tension provided by this invention determines the predicted stress deviation for the next layer by acquiring the film roll stress state, film roll radius state, and material elasticity state during the winding process. Then, based on this predicted value and historical stress deviation states, the reference tapered curve is dynamically corrected, and the target tension is compensated according to the current tension execution state before outputting the execution. This allows the internal stress evolution law of the film roll and the material elastic temperature drift characteristics to be incorporated into the closed-loop correction process of the tension setpoint. This enables the tapered curve to adaptively adjust to changes in film roll radius, material batch differences, ambient temperature drift, and winding speed fluctuations. This fundamentally solves the problem of coexistence of inner layer crushing and outer layer relaxation caused by the inability of the preset fixed curve to respond to changes in working conditions in existing tapered control strategies. It achieves dynamic equilibrium of the stress distribution across the entire layer, significantly improving the stability and consistency of the protective film winding quality. Meanwhile, by introducing the accumulated stress state inside the membrane roll as the basis for control decisions, this invention overcomes the limitation of traditional tension feedback control, which only focuses on the instantaneous tension value of the membrane surface and ignores the effect of interlayer stress accumulation. This effectively reduces the risk of material plastic deformation caused by stress concentration and extends the storage life and reliability of the membrane roll. Furthermore, based on real-time perception and compensation of the current tension execution state, this invention ensures that the generation of tension commands matches the actual output capability of the actuator, avoiding the decrease in control accuracy caused by the response deviation of the actuator. This further enhances the robustness and adaptability of the control system under all working conditions in the starting, stabilizing, and full-winding stages. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0040] Figure 1 This is a flowchart of a method for controlling the taper of the protective film winding tension according to an embodiment of the present invention.

[0041] Figure 2 This is an application scenario diagram of the tapered control method for the winding tension of the protective film according to an embodiment of the present invention. Detailed Implementation

[0042] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0043] Figure 1This is a flowchart of a method for controlling the taper of the protective film winding tension according to an embodiment of the present invention. Figure 1 As shown, the tapered control method for the winding tension of the protective film includes:

[0044] S1. The winding controller acquires the cumulative stress distribution of the wound macrolayer, the current film roll radius, the current winding speed, and the elastic modulus of the protective film corresponding to the current ambient temperature. Based on the stress transmission depth, radial position of the macrolayer, and candidate tension of the next layer obtained online, it calculates the predicted stress increment value generated by the next layer winding on each wound macrolayer. The normalized difference between the predicted stress increment value and the target stress increment is determined as the stress deviation prediction value.

[0045] Specifically, the winding controller does not treat each physical film layer as an independent calculation object. Instead, it merges the wound film layers into multiple macrolayers according to their radial positions and establishes a macrolayer state table. Each macrolayer corresponds to a continuous thickness range in the radial direction of the film roll. The macrolayer state table records at least the macrolayer number, macrolayer start radius, macrolayer end radius, macrolayer representative radius, macrolayer equivalent thickness, macrolayer winding time range, macrolayer average winding tension, macrolayer average winding temperature, macrolayer elastic modulus at winding, current cumulative equivalent stress, current target equivalent stress, and historical stress integral values. The macrolayer can be formed by merging a fixed number of physical film layers or by merging fixed radial thickness ranges. The macrolayer thickness is determined during the debugging phase based on the protective film thickness, winding control cycle, controller computing power, and allowable stress resolution, ensuring that the controller traverses the macrolayer state in each control cycle, rather than the states of tens of thousands of physical film layers.

[0046] Subsequently, the winding controller reads the current film roll radius. The current film roll radius can be obtained by converting the cumulative film length and effective protective film thickness using a laser displacement sensor, ultrasonic ranging sensor, or encoder. When both direct ranging data and kinematic conversion data are available, the winding controller verifies the geometric consistency between the roller core radius, cumulative film length, effective protective film thickness, and cumulative macrolayer thickness, and uses the data that satisfies the winding geometry as the current film roll radius. If the radius growth trend formed by a certain sampling radius is inconsistent with that of the cumulative film length, the controller does not directly use the sampling value for stress prediction, but instead recursively derives the current film roll radius based on the previous stable sampling radius and the incremental film length wound in this cycle.

[0047] Furthermore, the winding controller reads the current ambient temperature and determines the current elastic modulus based on the temperature-elastic modulus calibration curve of the protective film material. This temperature-elastic modulus calibration curve is formed from tensile test data of the same protective film material at multiple temperature points, or from material supply data combined with stable winding samples from the production line. In cases of material batch switching, equipment shutdown and restart, pressure roller adjustment, or significant changes in film surface condition, the winding controller performs a short-term identification process before formally entering stable winding to re-obtain the reference stress transfer depth corresponding to this batch or this startup.

[0048] In one implementation, the short-time identification is achieved using a recursive least squares method. The identification excitation signal is a small-amplitude pseudo-random binary sequence, step sequence, or ramp sequence superimposed on the current target tension; in a non-limiting embodiment, the excitation amplitude does not exceed ±3% of the rated tension, and the duration is 1 to 3 seconds. The winding controller collects motor current, angular velocity, angular acceleration, film roll radius, tension feedback, or floating roll feedback during the excitation period, and uses the stress transmission depth as the parameter to be identified, with the goal of minimizing the sum of squares of the tension response residual, radius compaction residual, or a weighted sum of the residuals of both; the forgetting factor of the recursive least squares method can be taken as 0.95 to 0.99. After identification convergence, the controller reverses the identified current stress transmission depth to a reference stress transmission depth. This serves as a reference parameter for this batch or this startup. The operating boundary of the stress transfer depth can be determined by the estimated covariance of the identification results, i.e., based on the three-times standard uncertainty interval formed by the tension response residuals during the short-time identification process. and It combines macrolayer thickness and total film roll thickness for physical constraints, without requiring separate online measurement of the pressure roller contact length.

[0049] Once the macrolayer state, current roll radius, current speed state, current elastic modulus, and reference stress transfer depth are all ready, the winding controller determines the next winding interval. The next winding interval is the radial interval after adding an effective layer thickness to the current roll radius; the effective layer thickness can be the nominal thickness of the protective film or the equivalent thickness corrected by the online compaction coefficient. Subsequently, the winding controller reads the candidate tension for the next layer from the corrected taper curve formed in the previous control cycle; when an effective macrolayer stress state has not yet been formed in the initial winding stage, the candidate tension for the next layer is determined by the reference taper curve, which is formed by the roller core radius, full roll radius, allowable stretch range of the protective film, full roll hardness requirement, and first roll debugging data.

[0050] In one embodiment, the predicted stress increment and the predicted stress deviation can be determined according to the following formula:

[0051]

[0052]

[0053]

[0054]

[0055] in, Number the macro layer; The equivalent stress transfer depth under the current working conditions, in meters; The reference stress transfer depth is obtained after short-time identification, in meters. This is the current elastic modulus, in Pa. The reference elastic modulus is expressed in Pa. This is the current volume diameter normalized position; The non-negative radius growth rate is calculated from the in-wound film length and effective layer thickness, in m / s. The radius growth rate is for reference under stable winding conditions, and the unit is m / s; , , These are dimensionless calibration coefficients. Since the quantities involved in exponential, hyperbolic tangent, and proportional operations are all dimensionless, there is no issue of directly adding parameters with different dimensions in the formulas.

[0056] In the stress increment prediction formula, For the next layer of winding to the first The predicted equivalent stress increments generated by each macro layer are expressed in Pa. The next candidate tension level is represented by N; The effective width of the protective film is measured in meters (m). This is the equivalent radius after the next layer is wound, in meters; For the first The representative radius of each macrolayer is expressed in meters. The unit area equivalent compression effect of the candidate tension of the next layer converted by the current roll diameter is expressed in Pa; the exponential term indicates that the newly added tension on the outside decreases as the radial distance increases when it is transmitted to the inner macrolayer. For the first A dimensionless expression of the current stress deviation of a macrolayer; For the deviation correction function within the recoverable operating range, either a hyperbolic tangent function or a limiting function with a linear tail can be used. If... If the stress falls within the operating range determined by the material's allowable compressive deformation, the distribution of qualified roll hardness samples, and the recoverable error of the control system, the controller participates in stress increment prediction according to this correction function; if If the operating range is exceeded, the controller generates a stress protection flag and transmits the flag to S4 to perform deceleration, alarm, or tension holding actions.

[0057] S2. The winding controller summarizes the predicted stress deviation and the historical stress integral value of the wound macro layer into a macro layer weight to obtain the comprehensive predicted stress deviation and the comprehensive historical stress integral value. It also dynamically corrects the slope of the reference taper curve in the next layer winding interval by combining the current tension execution deviation, and generates the corrected taper curve.

[0058] Specifically, the take-up controller first reads the predicted stress deviation, current cumulative equivalent stress, current target equivalent stress, and historical stress integral value from the macrolayer status table of each macrolayer. Then, for each macrolayer, it calculates the current stress deviation, which is a dimensionless quantity obtained by processing the difference between the current cumulative equivalent stress and the target equivalent stress of that macrolayer using a stress-normalized reference. The take-up controller recursively updates the current stress deviation with the historical stress integral value from the previous period, ensuring that the historical stress integral value reflects the continuous deviation state, rather than just the instantaneous disturbance within a single sampling period.

[0059] Furthermore, the winding controller determines the macrolayer weights for each macrolayer. These macrolayer weights can be determined solely by the stress transfer depth and the radial distance from the macrolayer to the outer surface of the film roll. When further differentiation of defect-sensitive areas is required, only three types of region weights—inner, middle, and outer layers—can be set, instead of assigning independent quality sensitivity coefficients to each macrolayer. The weights for these three regions are determined by the crushing sensitivity near the roll core, the relaxation sensitivity of the outer surface, and the contribution of the intermediate roll hardness. When regional difference data is lacking, the weights for all three regions can be uniformly set to 1, so that the macrolayer weights are determined solely by the stress transfer attenuation relationship.

[0060] In one implementation, the historical stress integral value, macro-layer weight, comprehensive deviation, taper correction factor, and the slope of the corrected taper curve can be determined according to the following formula:

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] in, For the first The historical stress integral value of each macrolayer after the current cycle update is a dimensionless quantity. This is the time interval corresponding to this update, in seconds; The stress deviation memory time constant, in seconds, can be identified from stress relaxation tests or stable production data of the protective film material. For the first The macrolayer weights of each macrolayer in the current membrane roll state are dimensionless quantities. This represents the number of macro layers that have already been formed. For the first The regional weights of each macrolayer are dimensionless. The exponent term expresses the sensitivity of the newly added outer layer tension to the transmission of macrolayers at different radial positions; the exponent is a ratio of lengths and is also dimensionless. The denominator is used to normalize the weights.

[0068] In the formula for the taper correction factor, As a comprehensive stress deviation prediction quantity, it is used to characterize the direction and degree of overall stress deviation that will be caused by the next layer of winding; The integrated historical stress values ​​are used to characterize the persistent stress deviation state in the wound macrolayer. This is the taper correction factor corresponding to the next layer of winding interval, and it is a dimensionless quantity; and These are dimensionless tuning coefficients, corresponding to prediction deviation correction and historical integral correction, respectively. This can be determined first through short-time speed change or short-time tension disturbance tests to ensure that the taper curve has a sufficient response to the predicted deviation of the next layer; the aforementioned It is possible Once determined, the controller is tuned based on the convergence rate of persistent stress deviations in multi-volume stable samples. By converging the taper correction factor into a predicted term and a historical integral term, the controller retains the core processing of correcting the taper based on historical stress accumulation, while reducing the engineering debugging difficulty caused by simultaneously tuning multiple coupled parameters.

[0069] In the slope correction formula, A dimensionless, constrained expression for the current tension execution deviation; The current estimated tension or feedback fusion tension is expressed in N; The current effective target tension, in N; This is the tension normalization reference value, in N; Used to limit single tension deviations within a recoverable correction range, avoiding abrupt slope changes caused by abnormal sampling. The slope of the corrected taper curve within the next winding interval is expressed in N / m. This represents the slope of the baseline taper curve within the next winding interval, expressed in N / m. If the current actual tension is higher than the target tension, then... If positive, the slope is adjusted towards a stronger decreasing direction after correction; if the current actual tension is lower than the target tension, then... If the value is negative, the slope will be adjusted in a weakening and decreasing direction after correction.

[0070] After the corrected slope calculation is completed, the winding controller uses the currently executed tension point as the continuous boundary point of the corrected taper curve at the current film roll radius, and generates the tension variation relationship within the next winding interval according to the corrected slope. If the corrected slope changes significantly relative to the previous layer's slope, the controller performs continuous processing on the curve according to the actuator's response capability and the allowable strain rate of the protective film, ensuring a smooth transition of the target tension between adjacent control cycles. Subsequently, the winding controller writes the corrected taper curve into the control buffer and uses this curve as the input for calculating the target tension of the next layer in S3.

[0071] S3. The winding controller calculates the target tension of the next layer based on the corrected taper curve, and estimates the current tension execution state under stable winding conditions by measuring motor current, angular velocity, angular acceleration and non-negative radius growth rate. Under unstable winding conditions, it switches to tension sensor or floating roller feedback control, and then converts the difference between the target tension and the estimated tension or feedback tension into a compensated tension command according to the radius nonlinear compensation relationship with gain constraint.

[0072] Specifically, the winding controller first reads the corrected taper curve from the control buffer and determines the target tension for the next layer based on the start and end radii of the next winding interval. The target tension for the next layer can be the tension at the midpoint radius of the corrected taper curve within the next winding interval, or it can be the average tension weighted by film length within that interval. When the sampling period is significantly shorter than the winding time for a single effective layer thickness, the winding controller can read the corresponding target tension from the corrected taper curve based on the real-time film roll radius in each sampling period. Subsequently, the winding controller reads the motor current, winding roller angular velocity, winding roller angular acceleration, current film roll radius, wound film length, bearing temperature, and optional tension sensor or floating roller feedback.

[0073] Furthermore, the winding controller first determines the operating status of the current working condition. If the linear velocity change rate, angular acceleration continuity, float roll position, tension feedback residual, and driver current state are all within the stable operating envelope formed by the equipment's rated capacity, historical stable sample distribution, and actuator response capability, it is determined to be a stable winding condition, and the current tension is estimated using the torque balance relationship based on variable inertia. If the current state is during winding start-up, film splicing, shutdown, rapid acceleration / deceleration, driver current limiting, or the float roll approaching the mechanical stroke boundary, it is determined to be an unstable winding condition. In this state, the winding controller reduces or suspends the weight of the variable inertia estimation results, prioritizes the use of tension sensor or float roll feedback to form the current tension execution state, and performs deceleration, tension maintenance, or smooth transition in S4.

[0074] In one implementation, the estimated tension and the compensated tension command under stable winding conditions can be determined according to the following formula:

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] in, The non-negative radius growth rate is calculated from the length of the wound membrane and is expressed in m / s. This is the current effective layer thickness, in meters (m). This represents the current linear velocity of the protective film, expressed in m / s. Instead of directly using the derivative of the radius measurement, sign errors caused by radius derivative noise under deceleration or vibration conditions can be avoided. This represents the equivalent moment of inertia of the current film roll and winding shaft, expressed in kg·m². This represents the fundamental moment of inertia of the roller core, winding shaft, and clamping mechanism, expressed in kg·m². The density of the protective membrane material is expressed in kg / m³. The non-negative rotational inertia growth rate caused by the entrained material is expressed in kg·m² / s.

[0082] In the formula for estimating tension, The estimated tension under stable winding conditions is expressed in N. The transmission ratio is dimensionless. Transmission efficiency, dimensionless; This is the motor torque constant, expressed in N·m / A. This is the current motor current, in amperes (A). The current bias is obtained by equipment calibration under zero torque or no-load conditions, and the unit is A; This is the angular acceleration of the winding roller, expressed in rad / s². The angular velocity of the take-up roller is expressed in rad / s. The frictional torque at the current angular velocity and bearing temperature is expressed in N·m and is obtained from the no-load operation calibration chart. The additional torque generated by the floating roller, magnetic powder brake, servo tension roller or other tension actuator, in N·m, is taken as 0 when no such mechanism is configured.

[0083] In the formula for the tension command after compensation The gain is for tension deviation compensation and is a dimensionless quantity. This is the normalized position of the current membrane roll radius; This is the tension normalization reference value, in N; and These are dimensionless compensation coefficients, corresponding to nonlinear compensation for roll diameter and compensation for inertia-torque ratio, respectively. The upper boundary of the gain... The following methods were used to determine the closed-loop response of the film roll section: Sinusoidal excitation, step excitation, or equivalent small perturbation excitation with an amplitude not exceeding 5% of the rated tension were applied to the initial roll section, the middle roll section, and the near-full roll section, respectively. The tension feedback closed-loop frequency response or step response was recorded. With a phase margin of not less than 45°, an amplitude margin of not less than 6 dB, or no sustained oscillation in the step response as constraints, the maximum allowable compensation gain for each roll section was calculated. Then, piecewise linear interpolation was performed according to the film roll radius to form... The function provides an operational, engineering-calibrated source for the upper boundary of the compensation gain, rather than a subjectively set fixed value.

[0084] After the estimated tension calculation is completed under stable winding conditions, the winding controller subtracts the current estimated tension from the target tension of the next layer to obtain the tension execution deviation. Then, it calculates the compensation gain based on the current roll diameter nonlinearity and the proportion of inertia torque. The compensation gain is then applied to the tension execution deviation to obtain the compensation amount. Finally, the target tension and the compensation amount are superimposed, and projected onto the tension operating boundary determined by the material's allowable tensile range, the rated torque of the winding motor, the output capacity of the tension actuator, the anti-slip constraint at the current radius, and the allowable strain rate of the protective film to obtain the compensated tension command. If the winding is in an unstable winding condition, the winding controller uses the feedback value from the tension sensor or floating roller to replace or dominate (\widehatT_k\), and limits the compensation gain to a narrower operating boundary corresponding to the unstable condition until the linear velocity, angular acceleration, and feedback residual re-enter the stable operating envelope.

[0085] S4. The winding controller outputs the compensated tension command to the winding drive system, and generates a winding roller speed control quantity in coordination with the current film roll radius and production line speed, so that the winding roller speed adjustment and the tension applied by the tension actuator are executed synchronously. At the same time, the film roll macrolayer status table is updated according to the actual execution feedback and protection status to complete the dynamic taper control of the protective film winding tension.

[0086] Specifically, the winding controller first reads the compensated tension command, current film roll radius, production line speed, and operating status flags output by S3. Then, it calculates the target angular velocity of the winding roller based on the kinematic relationship between the production line speed and the current film roll radius, matching the outer circumferential speed of the winding roller with the protective film speed. As the film roll radius gradually increases, the winding controller continuously reduces the target angular velocity of the winding roller. When the upstream traction roller or main line speed accelerates or decelerates, the winding controller synchronously updates the winding roller angular velocity reference and angular acceleration reference, and uses the angular acceleration reference for inertia compensation or feedback control of unstable operating conditions at the tension actuator.

[0087] Subsequently, the winding controller converts the compensated tension command into a corresponding execution quantity according to the execution structure of the winding drive system. For systems where tension is directly generated by the winding motor, the winding controller multiplies the compensated tension command by the current film roll radius to obtain the target tension torque of the winding shaft; then it superimposes the inertial torque corresponding to the target angular acceleration, the inertial increase torque caused by the wound material, and the frictional torque compensation; subsequently, it converts this into a motor current command based on the motor torque constant, transmission ratio, and transmission efficiency, and outputs it to the winding servo driver. For systems that use a winding motor to control speed and a floating roller or tension roller to control tension, the winding controller outputs an angular velocity command matching the linear velocity to the winding motor, and converts the compensated tension command into servo torque, air pressure, excitation current, or floating roller position command according to the tension actuator calibration curve. The tension actuator calibration curve is formed by both no-load calibration and film-bearing calibration, and can be recalibrated after changes in the batch of protective film material, film width, or film thickness.

[0088] Furthermore, before outputting the execution command, the winding controller performs continuous processing on the rate of change of the tension command. The operating boundary of this continuous processing is jointly determined by the motor current variation capability, the response speed of the tension actuator, the allowable strain rate of the protective film, the current winding linear speed, and the closed-loop stability margin. When the compensated tension command changes significantly compared to the previous control cycle, the winding controller distributes the command change amount to multiple sampling cycles for execution according to this operating boundary, and records the portion that is not executed in the current cycle as an execution residual. The execution residual is used to subsequently update the cumulative stress distribution and historical stress integral values, so that the film roll macrolayer state table reflects the actual execution state, rather than just recording the target command.

[0089] During execution, the winding controller collects motor current, winding roller angular velocity, winding roller angular acceleration, film roll radius, ambient temperature, tension actuator feedback, and optional tension sensor or floating roller feedback according to the sampling period. The controller determines whether the currently wound material has reached the closure condition of a macrolayer based on the cumulative wound film length and macrolayer thickness. If the closure condition has not yet been met, the actual winding tension, temperature, elastic modulus, and radius data of this period are incorporated into the currently forming macrolayer, updating the average winding state of that macrolayer. If the closure condition has been met, the current macrolayer is written to the film roll macrolayer state table, and a new record for the next macrolayer is created. For existing inner and middle macrolayers, the controller updates their cumulative equivalent stress based on the actual estimated tension or feedback tension, current elastic modulus, current film roll radius, and equivalent stress transmission depth. For newly formed outer macrolayers, the controller establishes an initial equivalent stress state based on their average winding tension and representative radius.

[0090] When S1 generates a stress protection flag, or S3 determines that the current winding condition is unstable, the winding controller enters a protective control state. To avoid repeated switching between the protection state and its deactivation, the winding controller uses a hysteretic state machine to manage the stress protection flag: the setting boundary of the stress protection flag is higher than the deactivation boundary, and the setting and deactivation boundaries are jointly determined by the material's allowable compressive deformation, the stress deviation distribution of the qualified roll sample, and the recoverable error of the control system. In a non-limiting embodiment, the setting condition can be set when the dimensionless stress deviation of the macrolayer reaches the higher boundary, and the deactivation condition can be set when it falls back to the lower boundary and is maintained for several macrolayers. The number of macrolayers maintained is jointly determined by the material stress relaxation time, the macrolayer thickness, and the current linear velocity. After entering the protection state, the controller reduces the winding speed, limits the rate of change of tension command, maintains a slow transition of the current tension command, prioritizes the use of tension sensor or floating roller feedback closed loop, and outputs stress deviation prompts to the host computer. After the macro layer stress deviation meets the release boundary, the macro layer count is completed at low speed, and the linear speed, angular acceleration, and tension feedback residual re-enter the stable operating envelope, the controller resumes the normal prediction, correction, and compensation process from S1 to S3.

[0091] Once the macrolayer state table of the membrane roll is updated, the winding controller uses the updated cumulative stress distribution, historical stress integral values, execution residuals, current material elastic state, reference stress transfer depth obtained from short-time identification, and current operating status flags as inputs for the next control cycle. This enables the next cycle to re-execute stress increment prediction, taper curve correction, tension execution estimation, and tension command compensation. Therefore, the compensated tension command is no longer merely the open-loop execution result of the reference taper curve, but a closed-loop control result formed by the current macrolayer stress state, historical cumulative stress state, material elastic modulus drift, membrane roll radius change, and drive execution feedback.

[0092] In summary, the tapered control method 100 for protective film winding tension based on embodiments of the present invention is explained. It determines the predicted stress deviation for the next layer by acquiring the film roll stress state, film roll radius state, and material elasticity state during the winding process. Then, based on this predicted value and historical stress deviation states, it dynamically corrects the reference tapered curve and compensates for the target tension according to the current tension execution state before outputting the execution. This allows the internal stress evolution law of the film roll and the material elastic temperature drift characteristics to be incorporated into the closed-loop correction process of the tension setpoint. This enables the tapered curve to adaptively adjust to changes in film roll radius, material batch differences, ambient temperature drift, and winding speed fluctuations. This fundamentally solves the problem of coexistence of inner layer crushing and outer layer relaxation caused by the inability of the preset fixed curve to respond to changes in working conditions in existing tapered control strategies. It achieves dynamic equilibrium of the stress distribution across the entire layer, significantly improving the stability and consistency of the protective film winding quality. Meanwhile, by introducing the accumulated stress state inside the membrane roll as the basis for control decisions, this invention overcomes the limitation of traditional tension feedback control, which only focuses on the instantaneous tension value of the membrane surface and ignores the effect of interlayer stress accumulation. This effectively reduces the risk of material plastic deformation caused by stress concentration and extends the storage life and reliability of the membrane roll. Furthermore, based on real-time perception and compensation of the current tension execution state, this invention ensures that the generation of tension commands matches the actual output capability of the actuator, avoiding the decrease in control accuracy caused by the response deviation of the actuator. This further enhances the robustness and adaptability of the control system under all working conditions in the starting, stabilizing, and full-winding stages.

[0093] Here, those skilled in the art will understand that the specific operations of each step in the tapered control system for the winding tension of the protective film described above have been referenced above. Figure 1 and Figure 2 The method for controlling the taper of the protective film winding tension has been described in detail, and therefore its repeated description will be omitted.

[0094] In summary, the tapered control system for protective film winding tension based on embodiments of the present invention is explained. It determines the predicted stress deviation for the next layer by acquiring the film roll stress state, film roll radius state, and material elasticity state during the winding process. Then, based on this predicted value and historical stress deviation states, it dynamically corrects the reference tapered curve and outputs the execution after compensating for the target tension according to the current tension execution state. This allows the internal stress evolution law of the film roll and the material elastic temperature drift characteristics to be incorporated into the closed-loop correction process of the tension setpoint. This enables the tapered curve to adaptively adjust to changes in film roll radius, material batch differences, ambient temperature drift, and winding speed fluctuations. This fundamentally solves the problem of coexistence of inner layer crushing and outer layer relaxation caused by the inability of the preset fixed curve to respond to changes in operating conditions in existing tapered control strategies. It achieves dynamic equilibrium of the stress distribution across the entire layer, significantly improving the stability and consistency of the protective film winding quality. Meanwhile, by introducing the accumulated stress state inside the membrane roll as the basis for control decisions, this invention overcomes the limitation of traditional tension feedback control, which only focuses on the instantaneous tension value of the membrane surface and ignores the effect of interlayer stress accumulation. This effectively reduces the risk of material plastic deformation caused by stress concentration and extends the storage life and reliability of the membrane roll. Furthermore, based on real-time perception and compensation of the current tension execution state, this invention ensures that the generation of tension commands matches the actual output capability of the actuator, avoiding the decrease in control accuracy caused by the response deviation of the actuator. This further enhances the robustness and adaptability of the control system under all working conditions in the starting, stabilizing, and full-winding stages.

Claims

1. A method for controlling the taper of the protective film winding tension, characterized in that, include: The stress state, radius state, and elastic state of the material of the protective film during the winding process are obtained, and the stress deviation prediction amount corresponding to the next layer of winding is determined based on the stress state, radius state, and elastic state of the material. Based on the predicted stress deviation and the historical stress deviation, the reference taper curve is corrected to obtain the corrected taper curve. The target tension is determined based on the corrected taper curve, and the target tension is compensated according to the current tension execution state to obtain the compensated tension command; The winding drive system is controlled to perform winding tension control according to the compensated tension command.

2. The method for controlling the taper of the protective film winding tension according to claim 1, characterized in that, The stress state of the membrane roll is characterized by the cumulative stress distribution of the wound macrolayers, which are formed by merging multiple continuous physical membrane layers according to the radial position of the membrane roll. Each wound macrolayer corresponds to a continuous thickness range in the radial direction of the membrane roll. The cumulative stress distribution is characterized by a membrane roll macrolayer state table, which includes macrolayer number, macrolayer starting radius, macrolayer ending radius, macrolayer representative radius, macrolayer equivalent thickness, macrolayer average winding tension, macrolayer average winding temperature, macrolayer elastic modulus at winding time, current cumulative equivalent stress, current target equivalent stress, and historical stress integral values.

3. The method for controlling the taper of the protective film winding tension according to claim 2, characterized in that, The determination of the stress deviation prediction for the next layer of winding is based on the film roll stress state, film roll radius state, and material elastic state, combined with the stress transmission depth obtained online, to predict the stress increment generated by the next layer of winding on each already wound macrolayer, and the normalized difference between the predicted value and the target stress increment that varies with the film roll radius and elastic modulus is used as the stress deviation prediction.

4. The method for controlling the taper of the protective film winding tension according to claim 3, characterized in that, The reference taper curve is corrected to obtain the corrected taper curve, which includes: The stress deviation prediction values ​​of each macro layer are weighted and summed to obtain the comprehensive stress deviation prediction value. The historical stress integral values ​​of each macro layer are weighted and summed to obtain the comprehensive historical stress integral value. The winding controller calculates the taper correction factor based on the predicted comprehensive stress deviation and the comprehensive historical stress integral value, and calculates the slope correction amount based on the current tension execution deviation. Calculate the slope of the corrected taper curve within the next winding interval using the following formula: in, To correct the slope of the tapered curve in the next winding interval, This is the taper correction factor. The slope of the reference taper curve within the next winding interval. This is a dimensionless, constrained expression for the current tension execution deviation. To protect the effective width of the membrane, As a reference for stress normalization, The dimensionless stress slope coupling coefficient, projection operator This means that the calculation results will be restricted to the operating boundary corresponding to the current radius.

5. The method for controlling the taper of the protective film winding tension according to claim 4, characterized in that, Compensating the target tension based on the current tension execution state includes: Under stable winding conditions, the winding controller estimates the current tension by measuring motor current, angular velocity, angular acceleration, and non-negative radius growth rate. Under unstable winding conditions, it switches to the tension sensor or floating roller feedback to obtain the current tension. The non-negative radius growth rate The in-wound film length and effective layer thickness are calculated using the following formula: in, For the current effective layer thickness, Given the current linear velocity of the protective film, This represents the current membrane roll radius.

6. The method for controlling the taper of the protective film winding tension according to claim 5, characterized in that, Compensating the target tension based on the current tension execution state further includes: The take-up controller uses the difference between the target tension and the current tension as the tension execution deviation, and calculates the compensation gain according to the following formula. : in, This is the normalized position of the current membrane roll radius. and The coefficient is a dimensionless compensation coefficient. This represents the equivalent moment of inertia of the current film roll and winding shaft. The non-negative growth rate of rotational inertia caused by the entrained material. The angular acceleration of the take-up roller. The angular velocity of the take-up roller, As the reference quantity for tension normalization, This represents the upper boundary of the compensation gain corresponding to the current radius. The winding controller applies the compensation gain to the tension execution deviation to obtain the compensation amount, and then superimposes the target tension with the compensation amount to obtain the compensated tension command.

7. The method for controlling the taper of the protective film winding tension according to claim 6, characterized in that, The winding drive system is controlled to perform winding tension control according to the compensated tension command, including: Based on the current film roll radius and production line speed, the winding roller speed control value is generated in coordination, so that the winding roller speed adjustment is synchronized with the tension applied by the tension actuator. When the stress deviates from the predicted amount and exceeds the recoverable operating range, the winding controller enters a protective control state and uses a hysteresis state machine to manage the stress protection flag. The setting boundary of the stress protection mark is higher than the release boundary. When the dimensionless stress deviation of the macrolayer enters the setting boundary, it is used as the setting condition. After falling back to the release boundary and continuously maintaining it for several macrolayers, it is used as the release condition. Once in protection mode, the controller performs one or more of the following protective operations: reducing the winding speed, limiting the rate of change of tension command, maintaining a slow transition of the current tension command, prioritizing the use of tension sensor or floating roller feedback closed loop, and outputting a stress deviation warning to the host computer.

8. A taper control system for the winding tension of a protective film, characterized in that, include: The data sensing and prediction module is used to acquire the film roll stress state, film roll radius state and material elastic state during the protective film winding process, and to determine the stress deviation prediction amount corresponding to the next layer winding based on the film roll stress state, film roll radius state and material elastic state. The taper curve correction module is used to correct the reference taper curve based on the predicted stress deviation and the historical stress deviation state, so as to obtain the corrected taper curve. The tension compensation module is used to determine the target tension based on the corrected taper curve, and to compensate the target tension according to the current tension execution state to obtain the compensated tension command. The execution and protection module is used to control the winding drive system to perform winding tension control according to the compensated tension command.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the taper control method for the winding tension of the protective film as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the taper control method for the winding tension of the protective film as described in any one of claims 1 to 7.

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