Tension control method and system for slitting process of stay wire packaging film

Abstract

The invention relates to the technical field of industrial automation control, in particular to a tension control method and system for the splitting process of a stay wire packaging film, and the method comprises the steps: obtaining the width, Poisson's ratio, elastic modulus, maximum rolling diameter and minimum rolling diameter of the stay wire packaging film to be split; the rolling diameter, the tension and the rolling layer number of the current moment of the stay wire packaging film in the slitting process are determined; an improved thickness integration method is used for obtaining the corrected rolling diameter; and corrected torque feedback is output through an improved PID control algorithm, the preset torque feedforward and the corrected torque feedback are summed to obtain the target torque of the stay wire packaging film splitting machine at the next moment, and the tension of the stay wire packaging film splitting machine at the next moment in the splitting process of the stay wire packaging film is controlled in real time based on the target torque. The problem that the control effect is poor due to accumulation of rolling diameter errors in the traditional slitting process is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial automation control. More particularly, the present application relates to a tension control method and system for a draw tape packaging film slitting process. BACKGROUND

[0002] With the rapid development of packaging, optical, electronic, printing and other industries, draw tape packaging film is used more and more in the production and processing link. As an essential and important equipment in the draw tape packaging film production line, the draw tape packaging film slitting machine is mainly used to slit the large roll mother roll of draw tape packaging film into multiple small rolls according to the predetermined specification, so as to meet the needs of different downstream processes or products. In the slitting process, the draw tape packaging film is usually in a continuous motion state, and the speed of winding and unwinding, the change of roll diameter and the stability of tension control directly determine the dimensional accuracy, flatness and final use performance of the draw tape packaging film product after slitting.

[0003] However, the draw tape packaging film generally has the characteristics of thin thickness, low elastic modulus and large ductility, and is easily affected by stretching, compression or slipping in the slitting process, thereby causing great difficulty in tension control. If the tension is too large, it may cause the draw tape packaging film to deform or break; if the tension is too small, it may cause loose winding, loose roll, wrinkles and other problems. Therefore, how to achieve stable and accurate control of tension in the whole draw tape packaging film slitting process is a core problem in the current slitting machine control system research and industrial application.

[0004] Although the traditional PID control is widely used in industrial automation, its parameters are usually fixed values, and it is difficult to consider adaptive adjustment of different roll diameter intervals and different material characteristics, which may cause unstable tension, especially when the physical parameters such as thickness, roll diameter and elastic modulus of the draw tape packaging film change significantly, the control performance will obviously decrease. In addition, the calculation of roll diameter plays a key role in tension control. The existing technology usually uses thickness integration method to estimate the roll diameter, that is, the roll diameter is calculated by the accumulation relationship between the material thickness and the number of winding layers. However, this method usually assumes that the thickness of the draw tape packaging film is constant, and does not consider the compression effect of the radial stress on the thickness during winding, which causes deviation between the actual roll diameter calculation and the true situation. This deviation is further transmitted to the torque control link, which may cause the error accumulation between the tension set value and the actual tension; thereby causing the problem of poor control effect due to roll diameter error accumulation in the traditional slitting process. SUMMARY

[0005] To solve the problem of poor control effect due to roll diameter error accumulation in the traditional slitting process proposed in the background technology, the present application provides solutions in the following aspects.

[0006] In a first aspect, the present application provides a tension control method for a stay wire packaging film slitting process, comprising: obtaining the width, Poisson's ratio, elastic modulus, maximum winding diameter and minimum winding diameter of the stay wire packaging film to be slit, and the winding diameter at the current time, the tension at the current time and the number of winding layers at the current time of the stay wire packaging film in the slitting; using an improved thickness integral method to obtain a corrected winding diameter, wherein the improved thickness integral method includes a thickness, which is positively correlated with a set thickness, and is inversely correlated with the number of winding layers and the radial stress of the stay wire packaging film at the current time; the radial stress is positively correlated with the elastic modulus, the difference between the maximum winding diameter and the current winding diameter, and the tension, and is inversely correlated with the Poisson's ratio, the current winding diameter and the width; using an improved PID control algorithm to output a corrected torque feedback, wherein the improved PID control algorithm includes a PID gain, which is positively correlated with an initial gain, the maximum winding diameter and the minimum winding diameter of the stay wire packaging film, and is inversely correlated with the average of the sum of the corrected winding diameter, the maximum winding diameter and the minimum winding diameter of the stay wire packaging film; summing a preset torque feedforward and the corrected torque feedback to obtain a next time target torque of the stay wire packaging film slitting machine, and controlling the tension of the stay wire packaging film slitting machine at the next time in the stay wire packaging film slitting process based on the target torque.

[0007] The technical solution above considers the physical characteristics, real-time winding diameter, number of winding layers and stress state of the stay wire packaging film, and combines the thickness integral method with adaptive PID control, to realize dynamic and accurate adjustment of the tension in the slitting process, make the winding diameter calculation more accurate and the tension response more timely and stable, thereby effectively inhibiting the tension instability problem caused by winding diameter change and stress fluctuation in the traditional slitting process, and solving the problem of poor control effect caused by winding diameter error accumulation in the traditional slitting process.

[0008] Further, The thickness at the current time is: , The set thickness is The exponential function with the natural constant as the base is The radial stress of the stay wire packaging film at the current time is The number of winding layers at the current time is .

[0009] The technical solution above couples the thickness of the stay wire packaging film with the radial stress and the number of winding layers it bears in the slitting process, dynamically describes the change law of the thickness with the force and winding change using an exponential decay relationship, so that the thickness calculation can more truly reflect the actual winding state, thereby improving the accuracy of the winding diameter estimation and providing a reliable basis for tension control.

[0010] Further,​​ Radial stress at time for: , The elastic modulus of the drawstring packaging film. The Poisson's ratio of the pull-string packaging film. Maximum roll diameter for The current roll diameter for The tension of the moment This refers to the width of the pull-string packaging film.

[0011] The above technical solution establishes a calculation model for the radial stress of the drawstring packaging film, combining the stress state of the drawstring packaging film during the slitting process with the material's mechanical properties and the winding process. This allows the radial stress to dynamically and accurately reflect the stress state of the drawstring packaging film under different roll diameters and tension conditions, thereby improving the accuracy of roll diameter correction and thickness calculation.

[0012] Furthermore, PID gain for: , This is the initial gain. Maximum roll diameter Minimum roll diameter The corrected roll diameter, These are the preset hyperparameters.

[0013] The above technical solution couples the PID gain with the real-time change of the roll diameter and introduces an adjustable exponential parameter to achieve adaptive adjustment of the gain. This enables the controller to automatically optimize the control intensity according to the changes in the winding state of the wire-drawing packaging film during the slitting process, thereby significantly improving the sensitivity and response speed of tension adjustment and effectively suppressing tension instability caused by changes in roll diameter or fluctuations in operating conditions.

[0014] Furthermore, the preset hyperparameter values ​​range from [0, +∞).

[0015] Furthermore, the PID gain includes: proportional gain, integral gain, and derivative gain.

[0016] Furthermore, the tension is acquired in real time by a tension sensor, and the tension acquired by the tension sensor is smoothed by a moving average filter.

[0017] Furthermore, the radial stress is standardized.

[0018] Furthermore, the real-time control includes inputting the target torque into the drive motor control unit of the wire drawing packaging film slitting machine to adjust the output of the drive motor in real time.

[0019] The above technical solution directly inputs the target torque to the control unit of the drive motor and adjusts the motor output in real time, realizing the rapid response and dynamic compensation of the slitting machine to tension under different roll diameters and working conditions. This effectively avoids tension fluctuations caused by system lag or changes in roll diameter, improves the stability and accuracy of tension control, and ensures that the stretch packaging film is always under uniform stress during the slitting process, thereby guaranteeing product quality and the continuity and reliability of the production process.

[0020] In a second aspect, the present invention provides a tension control system for the slitting process of a drawstring packaging film, comprising a memory and a processor, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, a tension control method for the slitting process of a drawstring packaging film as described above is implemented.

[0021] The beneficial effects of this invention are as follows: This invention comprehensively considers the physical characteristics, roll diameter variation, number of winding layers, and real-time tension of the stretch packaging film, and combines an improved thickness integral method with adaptive PID control to achieve dynamic and precise tension adjustment during the slitting process. This makes the roll diameter calculation more accurate and the tension response more timely and stable. At the same time, real-time acquisition and filtering ensure the reliability of the data, and the target torque is directly applied to the drive motor to achieve rapid feedback control. This effectively suppresses the problems of tension fluctuation and roll diameter error accumulation in the traditional slitting process, ensuring uniform force and stable operation of the stretch packaging film during the slitting process, and significantly improving slitting quality, production efficiency, and system control reliability. Attached Figure Description

[0022] Figure 1 This is a flowchart schematically illustrating a tension control method for a drawstring packaging film slitting process according to an embodiment of the present invention; Figure 2 This is a schematic block diagram illustrating the structure of a tension control system for a drawstring packaging film slitting process according to an embodiment of the present invention. Detailed Implementation

[0023] An embodiment of a tension control method for the slitting process of draw-string packaging film.

[0024] like Figure 1 The flowchart shown illustrates a tension control method for the slitting process of a drawstring packaging film according to an embodiment of the present invention, comprising the following steps: S1: Obtain the width, Poisson's ratio, elastic modulus, maximum roll diameter, and minimum roll diameter of the stretch packaging film to be slit, as well as the roll diameter, tension, and number of winding layers of the stretch packaging film at the current moment during slitting.

[0025] In a preferred embodiment, the tension data is acquired in real time by a tension sensor mounted on the slitting machine. Besides the tension parameter acquired in real time by the tension sensor, other parameters can also be obtained in various ways: the width of the drawstring packaging film can be input into the control system by the operator according to production process requirements before the slitting operation, or it can be automatically detected by a photoelectric detection device or a laser width measuring device; Poisson's ratio and elastic modulus, as inherent physical property parameters of the drawstring packaging film material, are provided by the material manufacturer and entered into the system before slitting; the maximum and minimum roll diameters are determined by the mechanical structure parameters of the slitting machine and can be stored in the system database during equipment initialization; the current roll diameter can be detected in real time by an encoder or laser rangefinder sensor mounted on the take-up shaft; and the number of take-up layers can be obtained by accumulating the number of rotations of the take-up shaft.

[0026] In actual operating environments, tension signals are easily affected by factors such as mechanical vibration, electrical noise, and environmental interference. Directly using the raw acquired signals can lead to significant data fluctuations, thus affecting the accuracy of tension control. Therefore, this embodiment preprocesses the raw signals acquired by the tension sensor. Specifically, this embodiment uses a moving average filtering method to smooth the tension signal. Moving average filtering, by weighting or equal-weighting the tension sample values ​​over several consecutive time points, can effectively reduce the impact of random noise on single samples and avoid abnormal pulses or instantaneous disturbances from interfering with the overall control results, thereby obtaining a more stable and reliable tension input signal.

[0027] Furthermore, in this embodiment, the window size of the moving average filter can be adaptively adjusted according to the slicing speed and sampling frequency. When the slicing speed is high, the window size is reduced accordingly to ensure that the filtered tension signal can still reflect dynamic changes in a timely manner; when the slicing speed is low, the window size can be appropriately increased to further improve the filtering effect and data stability.

[0028] S2: Obtain the corrected roll diameter using an improved thickness integral method.

[0029] In a preferred embodiment, the improved thickness integration method includes thickness, Thickness at any moment for: , To set the thickness, For the natural constant An exponential function with base 0. for The radial stress of the pull-string packaging film at a given time. for The number of layers in the winding process at any given time; By improving upon the traditional thickness integration method, the drawstring packaging film is... The thickness at any given time is represented as the product of the set thickness and the exponential decay function, where the exponential term is determined by the radial stress and the number of winding layers. This logically realizes the dynamic change law that the thickness gradually decreases as the stress increases and the number of layers accumulates. It retains the reference role of the reference thickness and introduces real-time correction of the stress and winding process, making the roll diameter calculation more in line with the actual working conditions, thereby effectively improving the accuracy and dynamic adaptability of roll diameter estimation.

[0030] Radial stress at time for: , The elastic modulus of the drawstring packaging film. The Poisson's ratio of the pull-string packaging film. Maximum roll diameter for The current roll diameter for The tension of the moment This refers to the width of the pull-string packaging film.

[0031] By constructing a radial stress calculation model, the real-time tension during the slitting process is combined with the width of the drawstring packaging film and the current roll diameter. Elastic modulus and Poisson's ratio are introduced to reflect the mechanical properties of the drawstring packaging film material. Simultaneously, the difference between the maximum roll diameter and the current roll diameter is used to characterize the dynamic changes in the winding process, thus logically achieving coupled calculation of material properties, stress state, and roll diameter evolution. The radial stress obtained in this way not only accurately reflects the stress situation of the drawstring packaging film under different roll diameters but also effectively avoids the calculation errors caused by traditional methods that ignore material properties or roll diameter differences.

[0032] The process of obtaining the roll diameter using the thickness integral method is existing technology and will not be described in detail here.

[0033] S3: Utilizes an improved PID control algorithm to output corrected torque feedback.

[0034] In a preferred embodiment, the improved PID control algorithm includes PID gains, which include proportional gain, integral gain, and derivative gain. PID gain for: , For the initial gain, Maximum roll diameter Minimum roll diameter The corrected roll diameter, The preset hyperparameters are defined as [0, +∞].

[0035] By improving the construction of the PID gain, the initial gain is used as a benchmark, and the sum of the maximum and minimum roll diameters is used as a scaling factor. The ratio of the corrected roll diameter to the average roll diameter is introduced as a dynamic adjustment term, which is then combined with preset hyperparameters. The adjustment intensity is flexibly controlled, thereby achieving adaptive adjustment of PID gain with changes in roll diameter; the dynamic characteristics of the winding process are reflected by the real-time change of roll diameter, and the control sensitivity is adjustable by means of hyperparameters, avoiding the problem of control performance degradation caused by fixed gain at different roll diameter stages, so that tension control can maintain good stability and response speed throughout the slitting process, thereby improving the control accuracy and slitting quality of the system.

[0036] S4: Summing the preset torque feedforward and the corrected torque feedback to obtain the target torque of the thread-wrap packaging film slitting machine at the next moment, and controlling the tension of the thread-wrap packaging film slitting machine at the next moment in the thread-wrap packaging film slitting process in real time based on the target torque.

[0037] In a preferred embodiment, the real-time control not only includes inputting the target torque to the drive motor control unit of the draw-out packaging film slitting machine to achieve dynamic adjustment of the drive motor output, but also further combines a motor speed detection device and a current sensor to monitor the motor operating status in real time, ensuring the accurate realization of the target torque in the actual output through a feedback closed loop. In this embodiment, the drive motor control unit can adopt vector control or direct torque control algorithms to achieve high-precision decoupled adjustment of motor speed and torque, thereby maintaining the system's rapid response and stable operation under different roll diameters and tension fluctuations.

[0038] The present invention comprehensively considers the physical characteristics, real-time roll diameter, number of winding layers, and stress state of the stretchable packaging film, and combines the thickness integral method with adaptive PID control to achieve dynamic and precise tension adjustment during the slitting process. This makes the roll diameter calculation and thickness correction more consistent with actual working conditions. At the same time, real-time tension acquisition and closed-loop control of the drive motor ensure the timeliness and stability of the control response, thereby effectively suppressing the tension instability problem caused by roll diameter changes, stress fluctuations, or system lag in traditional slitting. This ensures uniform stress and stable operation of the stretchable packaging film during the slitting process, significantly improving product quality and production efficiency.

[0039] An embodiment of a tension control system for the slitting process of draw-string packaging film: like Figure 2 As shown, a structural block diagram of a tension control system for the slitting process of a drawstring packaging film according to an embodiment of the present invention is included, comprising a processor and a memory.

[0040] This invention also provides a tension control system for the slitting process of draw-string packaging film. For example... Figure 2As shown, the system includes a processor and a memory, the memory storing computer program instructions, which, when executed by the processor, implement the tension control method for the thread-pulling packaging film slitting process according to the present invention.

[0041] The tension control system for the slitting process of the pull-string packaging film also includes other components well known to those skilled in the art, such as a communication interface. The settings and functions of these components are known in the art and will not be described in detail here.

[0042] In this invention, the aforementioned memory can be any tangible medium containing or storing a program that can be used or combined with an instruction execution system, apparatus, or device. For example, a computer-readable storage medium can be any suitable magnetic or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc., or any other medium that can be used to store desired information and can be accessed by an application, module, or both. Any such computer storage medium can be part of a device or accessible to or connected to a device. Any application or module described in this invention can be implemented by computer-readable / executable instructions stored or otherwise maintained on such a computer-readable medium.

[0043] In the description of this specification, "multiple" or "several" means at least two, such as two, three or more, unless otherwise explicitly specified.

[0044] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A tension control method for the slitting process of draw-string packaging film, characterized in that, include: Obtain the width, Poisson's ratio, elastic modulus, maximum roll diameter, and minimum roll diameter of the stretch packaging film to be slit, as well as the roll diameter, tension, and number of winding layers of the stretch packaging film at the current moment during slitting. The corrected roll diameter is obtained using an improved thickness integration method. The improved thickness integration method includes thickness, which is positively correlated with a set thickness and negatively correlated with the number of winding layers and radial stress of the pull-down packaging film at the current moment. The radial stress is positively correlated with the elastic modulus, the difference between the maximum roll diameter and the roll diameter at the current moment, and tension, and negatively correlated with Poisson's ratio, the roll diameter at the current moment, and width. The improved PID control algorithm outputs the corrected torque feedback. The improved PID control algorithm includes a PID gain, which is positively correlated with the initial gain, the maximum and minimum roll diameters of the drawstring packaging film, and negatively correlated with the mean of the sum of the corrected roll diameter, the maximum and minimum roll diameters of the drawstring packaging film. The preset torque feedforward and the corrected torque feedback are summed to obtain the target torque of the thread-stretch packaging film slitting machine at the next moment, and the tension of the thread-stretch packaging film slitting machine at the next moment during the thread-stretch packaging film slitting process is controlled in real time based on the target torque.

2. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, Thickness at any moment for: , To set the thickness, For the natural constant An exponential function with base 0. for The radial stress of the pull-string packaging film at a given time. for The number of layers at any given time.

3. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, Radial stress at time for: , The elastic modulus of the drawstring packaging film. The Poisson's ratio of the pull-string packaging film. Maximum roll diameter for The current roll diameter for The tension of the moment This refers to the width of the pull-string packaging film.

4. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, PID gain for: , This is the initial gain. Maximum roll diameter Minimum roll diameter The corrected roll diameter, These are the preset hyperparameters.

5. A tension control method for the slitting process of draw-string packaging film according to claim 4, characterized in that, The preset hyperparameter values ​​are in the range of [0, +∞).

6. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, The PID gain includes: proportional gain, integral gain, and derivative gain.

7. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, The tension is acquired in real time by a tension sensor, and the tension acquired by the tension sensor is smoothed by a moving average filter.

8. The tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, The radial stress is then standardized.

9. A tension control method for the slitting process of draw-string packaging film according to claim 1, characterized in that, The real-time control includes inputting the target torque into the drive motor control unit of the wire drawing packaging film slitting machine to adjust the output of the drive motor in real time.

10. A tension control system for the slitting process of draw-string packaging film, characterized in that, It includes a memory and a processor, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, a tension control method for the slitting process of a draw-line packaging film as described in any one of claims 1 to 9 is implemented.

Images