Feed packaging line film conveying tension self-adaptive adjusting device and method thereof

Abstract

The invention relates to the technical field of automatic packaging machinery and flexible material conveying control, in particular to a feed packaging line film conveying tension self-adaptive adjusting device and method. The device comprises a rack, a swing bracket, a porous sintered metal driving roller, a balance cylinder and an air supply detection system, the cylinders are communicated with inner cavities of the driving rollers through pipelines; the core of the method is that a fluid impedance analysis-based implicit sensing technology is adopted, and a thin film tensioning state is calculated by utilizing pipeline gas flow and pressure data; a traditional optical and contact type sensor is abandoned, the problem of detection distortion in a high-dust environment is effectively solved, physical damage to a fragile film is avoided, and non-contact and high-reliability tension adjustment under severe working conditions is achieved.

Description

Technical Field

[0001] This invention relates to the field of automated packaging machinery and flexible material conveying control technology, specifically to an adaptive tension adjustment device and method for film conveying in feed packaging lines. Background Technology

[0002] In the current film conveying environment of feed packaging lines, the work involves the coordination of upstream heavy-duty rolls and downstream thin films, and the production site is usually accompanied by high concentrations of dust pollution. To maintain constant tension during film conveying, existing technologies generally adopt traditional mechanical floating rollers or closed-loop control schemes based on optical or contact sensors. However, in the specific scenario of feed processing, the high dust environment can easily cause optical sensors to distort signals due to lens contamination, while contact sensors can easily cause surface damage to fragile films. At the same time, due to the significant dynamic mismatch between the huge rotational inertia of heavy-duty rolls and the low strength characteristics of films, existing rigid or simple pneumatic adjustment devices often cannot effectively absorb transient impact energy when dealing with high-speed start-stop and sudden speed changes due to their single damping characteristics or lag in response. This limitation of sensing methods and the lag in mechanical response lead to frequent film breakage due to tension overload or relaxation flutter and material piling caused by insufficient buffering on the production line, which seriously restricts the stability of packaging efficiency and finished product quality.

[0003] Therefore, how to achieve non-contact, precise sensing and adaptive, rapid buffering adjustment of film conveying tension while overcoming dust interference and inertial mismatch has become an urgent technical problem to be solved. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an adaptive adjustment device and method for film conveying tension in feed packaging lines, which can solve the technical problems existing in the prior art. Specifically, the technical solution of this invention is as follows: An adaptive tension adjustment device for film conveying in a feed packaging line includes: The frame has a horizontally mounted swing shaft at the top and a hinged seat at the bottom; the swing bracket is sleeved on the swing shaft at the top via a bearing to swing around the swing shaft. The drive roller assembly, installed at the lower end of the swing bracket, includes a hollow drive roller and a drive motor. The cylindrical surface of the drive roller is made of sintered metal porous material and densely covered with vent holes. The drive motor drives the drive roller to rotate. The balancing cylinder assembly includes a balancing cylinder and a connecting pipe. The tail of the balancing cylinder is hinged to the hinge seat of the frame, and the end of the piston rod is hinged to the lower middle part of the swing bracket. One of its chambers is directly connected to the internal cavity of the drive roller through the connecting pipe. A gas supply and detection system, connected to the connecting pipeline, includes a precision pressure regulating valve, a flow resistance element disposed downstream of the precision pressure regulating valve, a gas flow meter, a pressure sensor, a gas path switching valve, and a vacuum generator; wherein, the gas flow meter and the pressure sensor are located on the pipeline between the flow resistance element and the drive roller; The controller controls the drive motor, the precision pressure regulating valve, the gas flow meter, and the pressure sensor.

[0005] Preferably, the shaft of the drive roller is hollow, one end of the connecting pipe is connected to the lower chamber of the balance cylinder, and the other end is connected to the shaft of the drive roller through a rotary joint, forming a communicating vessel structure.

[0006] Preferably, the gas path switching valve is configured to switch the connecting pipeline to a positive pressure gas supply mode or a negative pressure adsorption mode under the control of the controller.

[0007] Preferably, the drive motor is directly connected to the drive roller via a rigid coupling, and the surface vent holes of the drive roller have a diameter in the micrometer range.

[0008] Preferably, the gas flow meter and the pressure sensor are mounted on the connecting pipe on the side closest to the drive roller.

[0009] Preferably, the balancing cylinder is a double-acting cylinder, which supports the swing bracket at a preset angle.

[0010] An adaptive adjustment method for film conveying tension in a feed packaging line includes: S1. Real-time acquisition of the first flow sensing data of the gas flow meter on the connecting pipeline; S2. Real-time acquisition of the first pressure sensing data of the pressure sensor on the connecting pipeline; S3. Calculate the first real-time fluid resistance value based on the first flow sensing data and the first pressure sensing data; S4. Obtain a preset reference fluid impedance model and compare the first real-time fluid impedance value with the reference fluid impedance model; S5. Based on the comparison results, the first real-time film tension state data is obtained.

[0011] Preferably, step S5 is followed by: S601, obtaining the rate of change and high-frequency component of the first real-time fluid impedance value within a set time interval; S602, determining that the film is in a relaxed flutter state when the first real-time fluid impedance value is lower than the first threshold of the reference fluid impedance model and is accompanied by high-frequency fluctuations; S603, controlling the gas supply and detection system to switch to negative pressure adsorption mode, using negative pressure to adsorb the film onto the surface of the drive roller.

[0012] Preferably, step S5 is followed by: S701, when the first real-time fluid impedance value is higher than the second threshold of the reference fluid impedance model and there is no fluctuation, it is determined that the film is in an over-tensioned state; S702, controlling the air supply and detection system to inject high-pressure pulsed airflow into the connecting pipeline; S703, using the high-pressure pulsed airflow to form an air cushion on the surface of the drive roller, forcing the film to produce a slight slippage to release tension.

[0013] Preferably, step S5 is followed by: S801, receiving an emergency stop command from an external packaging machine; S802, controlling the air supply and detection system to cut off the air supply and apply negative pressure to lock the film on the surface of the drive roller; S803, using the braking torque of the drive motor in conjunction with the frictional force on the surface of the drive roller to stop the film from being conveyed.

[0014] Compared with the prior art, the present invention has the following improvements and advantages: 1. This invention employs a latent sensing technology based on fluid impedance analysis, which calculates fluid impedance using gas flow and pressure data in a connected pipeline, thereby estimating the film tension state. This method eliminates traditional optical and contact sensors, effectively overcoming the defects of optical lens contamination and distortion caused by high concentrations of dust at the feed packaging site. It also avoids physical damage to the thin and fragile film surface caused by contact detection mechanisms, achieving non-contact, high-reliability tension sensing under harsh working conditions. 2. This invention constructs a pneumatic balancing system that directly connects a balancing cylinder to a sintered metal porous drive roller. When the upstream roll material's inertial lag causes a sudden increase in film tension that pulls the swing support, the transient high-pressure gas generated by the compression of the cylinder is directly introduced into the drive roller and ejected from the micropores, forming a high-pressure air cushion between the film and the roller surface within milliseconds, automatically reducing the coefficient of friction. This direct conversion mechanism from mechanical displacement signal to fluid dynamic signal realizes adaptive and rapid buffering of tension fluctuations, eliminating the elastic lag of traditional mechanical adjustment. 3. This invention designs a high-pressure pulsed airflow active control strategy. When the film is detected to be in an over-tensioned dead-stretch state, the system injects high-pressure pulsed airflow into the pipeline, instantly forming a high-rigidity air cushion on the surface of the drive roller, forcing a small amount of controlled slippage between the film and the roller surface. This pneumatic clutch mechanism can effectively release the accumulated tensile stress, playing an overload protection role similar to a mechanical safety clutch, and significantly reducing the probability of the film being torn. 4. This invention integrates a positive and negative pressure switching function. When the film is loose and fluttering or when an emergency stop is required, the vacuum generator switches to a negative pressure adsorption mode, using atmospheric pressure difference to tightly lock the film onto the surface of the drive roller. This not only eliminates aerodynamic instability and flutter under low tension, but also efficiently transmits the braking torque of the drive motor to the film during an emergency stop, preventing material stacking failures caused by film slippage and ensuring the high-speed and stable operation of the production line. Attached Figure Description

[0015] The present invention will be further explained below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall external structure of the device; Figure 2 This is a schematic diagram of the drive roller assembly structure of the device; Figure 3 This is a schematic diagram of the gas supply and detection system of the device; Figure 4 This is a schematic diagram of the internal structure of the device's balance cylinder assembly; Figure 5 This is a flowchart of the method of the present invention; In the diagram: 100, frame; 110, upper crossbeam; 120, swing shaft; 200, swing bracket; 210, bearing; 300, drive roller assembly; 310, drive roller; 311, vent hole; 320, rotating shaft; 330, drive motor; 340, rigid coupling; 400, balance cylinder; 410, lower chamber; 500, connecting pipeline; 510, flow resistance element; 520, rotary joint; 600, gas supply and detection system; 610, precision pressure regulating valve; 620, gas flow meter; 630, pressure sensor; 640, gas path switching valve; 650, vacuum generator. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0017] Example 1 Please see Figures 1-4 An adaptive tension adjustment device for film conveying in a feed packaging line includes: The frame 100 has a horizontally mounted swing shaft 120 on the upper part and a hinge seat on the lower part. The upper end of the swing bracket 200 is sleeved on the swing shaft 120 through the bearing 210 so as to swing around the swing shaft 120. The drive roller assembly 300 is installed at the lower end of the swing bracket 200 and includes a hollow drive roller 310 and a drive motor 330. The cylindrical surface of the drive roller 310 is made of sintered metal porous material and densely covered with vent holes 311. The drive motor 330 drives the drive roller 310 to rotate. The balancing cylinder assembly includes a balancing cylinder 400 and a connecting pipe 500. The tail of the cylinder body of the balancing cylinder 400 is hinged to the hinge seat of the frame 100, and the end of the piston rod is hinged to the lower middle part of the swing bracket 200. One of its chambers is directly connected to the internal cavity of the drive roller 310 through the connecting pipe 500. A gas supply and detection system 600, connected to the connecting pipeline 500, includes a precision pressure regulating valve 610, a flow resistance element 510 disposed downstream of the precision pressure regulating valve 610, a gas flow meter 620, a pressure sensor 630, a gas path switching valve 640, and a vacuum generator 650, used to detect the fluid state within the pipeline; wherein, the gas flow meter 620 and the pressure sensor 630 are located on the pipeline between the flow resistance element 510 and the drive roller 310; The controller controls the drive motor 330, the precision pressure regulating valve 610, the gas flow meter 620, and the pressure sensor 630. This embodiment constructs an adaptive tension adjustment device for film conveying in a feed packaging line. Its core lies in using the aerodynamic balance and fluid-structure interaction characteristics of porous media to solve the dynamic mismatch problem between heavy-duty roll material and thin film. The main structure of the device is supported by a frame 100. A swing shaft 120 is installed on the upper crossbeam 110 of the frame 100. The swing support 200 is suspended on the shaft through a bearing 210, forming a physical inverted pendulum structure. This structure allows the swing support 200 to generate passive displacement under the action of film tension. The bottom end of the swing bracket 200 is equipped with a drive roller assembly 300, wherein the drive roller 310 is made of sintered metal porous material and its cylindrical surface is densely covered with air vents 311. This structure makes the drive roller 310 not only a traction component, but also an interface for airflow to contact the film. The drive motor 330 is directly connected to the drive roller 310 to provide rotational power. The key tension adjustment mechanism is achieved through a balancing cylinder assembly. The balancing cylinder 400 is connected between the frame 100 and the swing support 200. Its unique feature is that one chamber of the cylinder is directly connected to the internal cavity of the drive roller 310 through a connecting pipe 500. The air supply and detection system 600 is connected to this pipe and includes a precision pressure regulating valve 610, a gas flow meter 620, a pressure sensor 630, an air path switching valve 640, and a vacuum generator 650. During operation, the precision pressure regulating valve 610 sets the base back pressure. In order to ensure the effectiveness of the pneumatic feedback mechanism and prevent the transient pressure gain generated by the compression of the balance cylinder 400 from being offset by the pressure stabilizing overflow function of the precision pressure regulating valve 610, a flow resistance element 510, such as a one-way throttle valve or a pneumatic impedance formed by a long pipeline, is installed on the pipeline between the precision pressure regulating valve 610 and the balance cylinder 400 to construct a transient pressure isolation zone. Pressure sensor 630 and gas flow meter 620 are explicitly installed downstream of flow resistance element 510, that is, between flow resistance element 510 and drive roller 310 / balance cylinder 400, inside the transient pressure isolation zone, to ensure that high-frequency pressure fluctuation signals generated by cylinder compression can be detected; if flow resistance element 510 is a one-way throttle valve, its installation direction is set as follows: the free conduction direction points to drive roller 310 and balance cylinder 400 to ensure sufficient air supply to maintain the air cushion, while the throttling direction points to precision pressure regulating valve 610 to generate high damping during backflow and prevent instantaneous gas depressurization; When the film tension suddenly increases due to the inertial lag of the upstream roll, the taut film pulls the swing bracket 200 to swing, forcing the piston of the balance cylinder 400 to compress the chamber. Due to the obstruction of the flow resistance element 510, the gas cannot flow back to the pressure regulating valve to exhaust instantly, resulting in an instantaneous increase in the air pressure inside the chamber. Due to the principle of communicating vessels, the increased air pressure is quickly transmitted to the inside of the drive roller 310 and ejected from the vent hole 311, forming an instantaneous high-pressure air cushion between the film and the roller surface, changing the coefficient of friction, thereby achieving adaptive buffering of tension. This embodiment is a further specification of the air circuit connection structure; in order to ensure the airtightness and connectivity between the rotating component and the stationary pipeline, the shaft 320 of the drive roller 310 is designed as a hollow structure; one end of the connecting pipeline 500 is connected to the lower chamber 410 of the balance cylinder 400, i.e. the pressure side, and the other end is connected to the shaft 320 of the drive roller 310 through a high-speed rotary joint 520; in order to reduce rotational friction and ensure long-term airtightness, the rotary joint 520 preferably adopts a non-contact labyrinth seal structure or a low-friction coefficient silicon carbide mechanical seal structure; This connection method constructs a variable volume communicating vessel system with continuous micro-venting characteristics. It is not an absolutely sealed system. Although there are vent holes 311 on the surface of the drive roller 310 for venting, the system can still maintain quasi-static balance due to the small aperture and sufficient air supply. This allows the pressure fluctuations in the lower chamber 410 of the balance cylinder 400 to be transmitted to the inside of the drive roller 310 without loss and with low delay. When the swing bracket 200 swings down due to increased tension, the volume of the lower chamber 410 decreases, and the compressed gas is pressed into the drive roller 310 through the rotating shaft 320, directly converting into buoyancy force acting on the film surface. This realizes the direct conversion of mechanical displacement signal into hydrodynamic signal. This embodiment extends the functionality of the gas supply system; the gas supply and detection system 600 further integrates a vacuum generator 650 and a gas path switching valve 640; the gas path switching valve 640 is configured as a two-position three-way or three-position five-way solenoid valve, which can quickly change the airflow direction in the pipeline under the command of the controller; in the positive pressure gas supply mode, the system performs the above-mentioned air flotation buffer function; while in the negative pressure adsorption mode, the vacuum generator 650 works, a negative pressure is formed in the pipeline, and external air is drawn into the drive roller 310 through the gap between the film and the roller surface, using the atmospheric pressure difference to tightly adsorb and lock the film onto the surface of the drive roller 310; this dual-mode switching design enables the device to not only provide air cushion lubrication during high-speed conveying, but also to provide extremely high static friction during emergency stops or starts, preventing the film from slipping or loosening; This embodiment optimizes the drive transmission and the microstructure of the roller surface. The drive motor 330 is directly connected to the drive roller 310 through a rigid coupling 340, eliminating the traditional belt or gear reduction mechanism, eliminating transmission gaps and elastic hysteresis, and ensuring that the motor torque can be transmitted to the roller surface in milliseconds. This, combined with the control algorithm, achieves high-frequency response. At the same time, the pore size of the vent holes 311 on the surface of the drive roller 310 is limited to the micrometer level, such as 5-20 micrometers. Compared with large-diameter openings, this microporous structure can generate a more uniform and dense laminar air film, avoiding local airflow concentration that could cause film bulging or damage, and ensuring the uniformity of the air cushion stiffness. This embodiment is a refinement of the sensor layout and support structure; the gas flow meter 620 and pressure sensor 630 are deliberately installed on the connecting pipe 500 near the drive roller 310. This near-end installation strategy aims to minimize the pressure wave transmission delay caused by the pipe length and ensure that the detection data can truly reflect the flow field state inside the drive roller 310; in addition, the balance cylinder 400 is a double-acting cylinder, which, in addition to being a pressure generating element, also plays an elastic support role, maintaining the swing bracket 200 at a preset balance angle, absorbing low-frequency mechanical vibrations during the conveying process, and preventing the device from resonating.

[0018] Example 2 Please see Figures 1-5 An adaptive adjustment method for film conveying tension in a feed packaging line includes: S1. Real-time acquisition of the first flow sensor data of the gas flow meter 620 on the connecting pipeline 500; S2. Real-time acquisition of the first pressure sensing data of the pressure sensor 630 on the connecting pipeline 500; S3. Calculate the first real-time fluid resistance value based on the first flow sensing data and the first pressure sensing data; S4. Obtain the preset reference fluid impedance model and compare the first real-time fluid impedance value with the reference fluid impedance model. S5. Based on the comparison results, calculate and obtain the first real-time film tension state data; This embodiment provides a control method based on fluid impedance analysis. This method uses the fluid medium as a hidden sensor, which solves the problem of easy failure of optical or contact sensors in dusty environments. The specific steps include: S1, acquiring the first flow sensing data of the gas flow meter 620 on the connecting pipe 500 in real time; S2, acquiring the first pressure sensing data of the pressure sensor 630 on the connecting pipe 500 in real time; the controller performs the above acquisition at a high sampling rate, such as 1kHz, to ensure the real-time performance of the data. To ensure the accuracy and traceability of the above fluid impedance analysis calculations, this embodiment provides the following unified and explicit definitions for the symbols and units of physical quantities involved in subsequent calculation formulas: Fluid resistance, characterizing the degree to which the vent 311 is covered, is measured in units of... ; The real-time gas pressure in the connecting pipe 500 corresponds to the following formula: or ; The raw gas pressure value within the connecting pipe 500, collected in real time by pressure sensor 630, is expressed in units of... ; The actual pressure value used to calculate impedance after dynamic compensation correction, in units of... ; The real-time gas volumetric flow rate in the connecting pipe 500 corresponds to the following formula: The unit is ; Non-resistive pressure compensation caused by transient changes in cylinder volume, in units of... ; The aerodynamic dynamic response time constant of the system characterizes the hysteresis characteristic of pressure buildup, and its unit is 1. ; : Rate of change of pressure over time, in units of ; The sampling time interval of the control system, in units of ; Total equivalent volume of the system, including piping volume. The equivalent volume of the cavity of the balance cylinder 400 and the drive roller 310 The unit is ; Gas polyvariance index, dimensionless, is taken as 1.4 under the adiabatic approximation in this embodiment; : Flow safety threshold, a lower limit for calculations to prevent division by zero errors, in units of . For example, corresponding to 0.1 L / min; : These refer to the standard tension N and the corresponding steady-state standard fluid impedance in the offline calibration experiment, respectively. ); The fitting coefficients of the second-order polynomial regression equation in the baseline fluid impedance model, with units of _____. ; The noise standard deviation of the fluid impedance measurement values ​​under no-load stable operation of the system, in units of ; The preset fixed equivalent volume of the cylinder and drive roller 310 cavity when the piston of the balance cylinder 400 is in the designed balanced position, in units of... ; S3. Calculate the first real-time fluid resistance value based on the first flow rate sensing data and the first pressure sensing data. This resistance value is calculated based on fluid mechanics principles using the ratio of pressure to flow rate, reflecting the degree to which the vent holes 311 on the surface of the drive roller 310 are covered by the thin film. The formula is as follows: ; S4. Obtain the preset reference fluid impedance model and compare the first real-time fluid impedance value with the reference fluid impedance model. The reference fluid impedance model is constructed through offline calibration experiments, specifically by applying a series of known standard tensions while the drive roller 310 is stationary or rotating at a constant speed. Record the corresponding steady-state fluid resistance value. The tension-resistance characteristic curve was generated by fitting using the least squares method. Alternatively, a discrete lookup table can be constructed to establish the mathematical relationship between input tension and output impedance; specifically, to balance computational efficiency and nonlinear fitting accuracy, the function... It was constructed to fit using a second-order polynomial regression model: ; in, This represents the real-time fluid impedance value; where, The fitting coefficients are calculated using offline calibration experimental data. To ensure the consistency of dimensions on both sides of the formula, i.e., tension... The unit is N, and the units of each coefficient are strictly defined as follows: The unit is , The unit is , The unit is N; For fluid resistance variables; To address the interference of transient pressure rise caused by cylinder compression during the pneumatic balancing buffering process in Example 1 on impedance calculation, the reference fluid impedance model also includes dynamic pressure compensation logic, introducing the pressure change rate as a correction factor to determine transient increments. To ensure calculation accuracy, the controller... Real-time dynamic adjustment To avoid numerical divergence at extremely low flow rates, the pressure change rate is calculated using the first-order backward difference method in the specific implementation of the digital controller. ; in, For the current number Pressure value per sampling period For the previous one Pressure value per sampling period The sampling time interval; when detected When the set threshold is exceeded, it is identified as a mechanical buffering action of the cylinder, and the model automatically deducts the non-resistive pressure increment caused by the cylinder's variable volume effect; specifically, this non-resistive pressure increment The calculation follows a modified formula derived from the gas law: ; in, In its physical essence, it is defined as the aerodynamic dynamic response time constant of the system, and its calculation formula is: ; in, For the current number Real-time flow measurement values ​​for each sampling period; function Indicates taking and The larger value in the formula is used to prevent the denominator from being zero. This formula shows that under low flow conditions, the system's inflation time constant increases, the pressure build-up hysteresis effect intensifies, and the compensation amount... The weight of increases accordingly; its physical meaning is to characterize the lag time of pressure establishment; in this formula, Defined as the gas polyvariance index, considering that the cylinder compression buffer process in this device is extremely short and heat cannot be transferred in time, approximating an adiabatic process, therefore, in this embodiment... Take the adiabatic index of air as 1.4; if applied to a low-speed quasi-static process, The measured values ​​can be taken between 1.0 and 1.4; regarding the boundary conditions and dynamic characteristics of the parameters in the formula, this embodiment defines the following to eliminate calculation errors: about The total equivalent volume of the system is determined by the volume of the piping. The equivalent volume of the cavity of the balance cylinder 400 and the drive roller 310 Composition; Given that the precision pressure regulating valve 610 in this embodiment is set with a basic back pressure and no cylinder position sensor is provided, it is impossible to accurately reverse the real-time stroke of the cylinder through static pressure. However, considering that under normal conveying conditions, the swing bracket 200 mainly swings slightly around a preset balance angle, the transient change in cylinder volume relative to the total volume including the long pipeline Since the proportion is extremely small, this embodiment adopts the preset balanced volume method, that is... The volume is set to a fixed value corresponding to the swing bracket 200 being in the designed equilibrium position, thereby simplifying the calculation model and ensuring the real-time operational efficiency of the controller; based on the above-mentioned preset equilibrium volume method, the total equivalent volume of the system is... The calculation formula is defined as follows: ; in, For the fixed geometric volume of the connecting pipe 500, The preset fixed volume for when the balance cylinder 400 is in the designed balance position; To verify the validity of this assumption, an error analysis was performed in this embodiment: Under typical buffer conditions, the compression stroke of the cylinder piston is usually less than 5mm, resulting in a volume change... Only accounting for a portion of the total equivalent volume of the system The error ranges from 1.5% to 2.5%. Experimental data shows that ignoring the fluid impedance calculation error caused by the volume change, the error is controlled within ±3%. This error range is much smaller than the dead zone range of the judgment threshold in the benchmark fluid impedance model, which is usually ±10%. Therefore, this simplification process significantly improves the response speed of the algorithm without reducing the detection accuracy. Regarding real-time intake airflow The calculation overflow that may occur in the denominator is due to the membrane being stretched and blocking the vent 311. Under these operating conditions, the controller is set with a flow safety threshold. For example, 0.1 L / min, when detected When the controller determines that the system has entered the high impedance region, it will force an instruction. Stay based on The calculated maximum saturation value is used to prevent numerical divergence. Based on the above corrections, the controller will collect pressure values ​​in real time. Subtract the increment Get corrective pressure The first real-time fluid impedance value after dynamic compensation is calculated according to the following formula. : ; This decouples the actual fluid resistance change caused solely by the membrane covering the vent 311.

[0019] S5. Based on the comparison results, the first real-time film tension state data is obtained. The system specifically performs the inverse operation of reverse table lookup or substitution into the fitting function to convert the fluid resistance value after dynamic compensation and correction into a specific tension value. For example, when the film is tightly attached to the roller surface, the vent 311 is blocked, which is high resistance. When the film is relaxed, it is low resistance, thus realizing non-contact quantitative sensing of film tension. This embodiment refines the control strategy for thin film relaxation conditions. After step S5, the system executes S601 to acquire the rate of change and high-frequency component of the first real-time fluid impedance value within a set time interval. The high-frequency component is extracted using a digital high-pass filter with a cutoff frequency of 10Hz-50Hz. This frequency band is chosen to effectively filter out low-frequency background drift caused by changes in roll diameter and mechanical transmission eccentricity, while retaining the flutter characteristic signal caused by aerodynamic instability of the thin film. It filters out low-frequency drift caused by roll diameter changes, retains the rapid fluctuation signal caused by thin film flutter, and calculates the root mean square value of this signal as the fluctuation intensity. The discrete domain calculation formula for the fluctuation intensity is defined as: ; The fluctuation intensity was ensured by introducing square root calculation. Dimensions and fluid resistance The dimensions are consistent, all being [missing information]. During the calculation process, if within the current sampling period This would make the corrected real pressure satisfy: ; Among them, the total equivalent volume of the system satisfy: ; This allows for a direct comparison of physical magnitudes with the threshold values ​​in the benchmark fluid impedance model; where, This represents the fluctuation intensity value. The total number of sampling points within a set time interval. This is the sampled value of the i-th high-frequency component of the fluid impedance after high-pass filtering; S602. When the first real-time fluid impedance value is lower than the first threshold of the reference fluid impedance model and is accompanied by high-frequency fluctuations, the thin film is determined to be in a relaxed flutter state; the first threshold is defined as... Its value is 70%-80% of the normal operating standard impedance value. This range is based on the fluid lubrication theory and corresponds to the critical impedance range where the laminar air film on the surface of the microporous medium begins to break and transform into turbulence. This physical limit represents the critical point at which the film begins to detach from the roller surface and form an air gap. When the real-time impedance value is lower than this threshold Furthermore, the RMS value of the aforementioned high-frequency components exceeds the preset background noise limit, which is set as the standard deviation of the noise measured under no-load operating conditions. 3 times, that is Criteria are established to ensure the confidence level of flutter detection and to determine whether flutter has occurred; S603, the control air supply and detection system 600 switches to negative pressure adsorption mode, using negative pressure to adsorb the film onto the surface of the drive roller 310; the rotation of the drive roller 310 is used to tighten the accumulated film and eliminate the loose flutter phenomenon. This embodiment refines the control strategy for over-tensioned thin films. After step S5, in step S701, when the system detects that the first real-time fluid impedance value is consistently higher than the second threshold of the reference fluid impedance model, and the signal curve is flat without fluctuations, it determines that the thin film is in an over-tensioned, dead-stretch state, at which point there is a risk of breakage. The second threshold is defined as... Its value is 120%-150% of the impedance value corresponding to the maximum allowable tension before the yield limit of the film in the reference fluid impedance model. This range of values ​​can effectively distinguish between normal high-tension working conditions and dangerous mechanical dead point conditions. S702, the controller commands the air supply and detection system 600 to inject high-pressure pulsed airflow into the connecting pipe 500; the control parameters of the high-pressure pulsed airflow are set as follows: the pressure amplitude of the pulse reaches 2.0 to 3.0 times the current base back pressure. This pressure amplitude is verified to ensure that the final pressure acting on the film surface after the micro-hole throttling effect of the drive roller 310 is still far below the yield strength limit of the feed packaging film, and the duration of a single pulse is strictly controlled between 10ms and 50ms. S703. The pulsed airflow instantly forms a high-rigidity air cushion on the surface of the drive roller 310, forcibly lifting the film and changing the friction mode between the film and the roller surface from dry friction to air-floating friction, generating a small amount of controlled slippage. This small amount of slippage can release the accumulated tensile stress, playing a role similar to the slippage protection of a mechanical clutch, thereby preventing the film from being torn. This embodiment is a refinement of the control strategy for emergency shutdown conditions; when the production line malfunctions and needs to be stopped urgently, S801, the controller receives an emergency stop command from the external packaging machine; S802, in order to overcome the huge rotational inertia of the upstream heavy-load roll material and prevent it from continuing to feed film and causing material accumulation, the controller quickly cuts off the air supply and applies high-intensity negative pressure, using atmospheric pressure to instantly lock the film on the surface of the drive roller 310, making the film and the drive roller 310 a moving whole; S803 Simultaneously, the drive motor 330 applies the maximum braking torque, effectively transmitting the braking force to the film through the locked film interface. Combined with the high friction of the drive roller 310 surface, the film is forced to stop conveying in a very short time. Given that the main body of the device is an inverted pendulum structure, in order to prevent the huge tension change at the moment of emergency braking from causing the swing bracket 200 to swing violently or hit the limit, during this process, the controller synchronously controls the balance cylinder 400 to lock the two-chamber air passage or fill it with high-pressure gas to form a rigid support. The pressure resistance of the cylinder is used to counteract the overturning torque generated by the emergency stop, ensuring the accuracy and control of the stopping process.

[0020] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A film conveying tension adaptive adjustment device for a feed packaging line, characterized in that, include: The frame (100) has a horizontally mounted swing shaft (120) on the upper part and a hinge seat on the lower part; The upper end of the swing bracket (200) is sleeved on the swing shaft (120) via a bearing (210) to swing around the swing shaft (120); The drive roller assembly (300) is installed at the lower end of the swing bracket (200) and includes a hollow drive roller (310) and a drive motor (330). The cylindrical surface of the drive roller (310) is made of sintered metal porous material and densely covered with vent holes (311). The drive motor (330) drives the drive roller (310) to rotate. The balancing cylinder assembly includes a balancing cylinder (400) and a connecting pipe (500). The tail of the cylinder body of the balancing cylinder (400) is hinged to the hinge seat of the frame (100), and the end of the piston rod is hinged to the lower middle part of the swing bracket (200). One of its chambers is directly connected to the internal cavity of the drive roller (310) through the connecting pipe (500). A gas supply and detection system (600) is connected to the connecting pipeline (500) and includes a flow resistance element (510) downstream of a precision pressure regulating valve (610), a gas flow meter (620), a pressure sensor (630), a gas path switching valve (640), and a vacuum generator (650); wherein the gas flow meter (620) and the pressure sensor (630) are located on the pipeline between the flow resistance element (510) and the drive roller (310); The controller controls the drive motor (330), the precision pressure regulating valve (610), the gas flow meter (620), and the pressure sensor (630). The shaft (320) of the drive roller (310) is hollow. One end of the connecting pipe (500) is connected to the lower chamber (410) of the balance cylinder (400), and the other end is connected to the shaft (320) of the drive roller (310) through a rotary joint (520), forming a communicating vessel structure. The controller is configured to calculate the real-time fluid impedance value based on the real-time gas volumetric flow rate obtained by the gas flow meter (620) and the real-time gas pressure obtained by the pressure sensor (630). The calculation formula is: ,in For real-time gas pressure, The real-time gas volume flow rate is calculated, and the calculated real-time fluid impedance value is compared with a preset reference fluid impedance model to deduce the true tension state of the membrane.

2. The adaptive tension adjustment device for film conveying in a feed packaging line according to claim 1, characterized in that, The gas path switching valve (640) is configured to switch the connecting pipeline (500) to a positive pressure gas supply mode or a negative pressure adsorption mode under the control of the controller.

3. The adaptive tension adjustment device for film conveying in a feed packaging line according to claim 1, characterized in that, The drive motor (330) is directly connected to the drive roller (310) via a rigid coupling (340), and the surface vent holes (311) of the drive roller (310) have a diameter of micrometers.

4. The adaptive tension adjustment device for film conveying in a feed packaging line according to any one of claims 1 to 3, characterized in that, The gas flow meter (620) and the pressure sensor (630) are mounted on the connecting pipe (500) on the side near the drive roller (310).

5. The adaptive tension adjustment device for film conveying in a feed packaging line according to any one of claims 1 to 3, characterized in that, The balancing cylinder (400) is a double-acting cylinder, which supports the swing bracket (200) at a preset angle.

6. A control method applied to the adaptive tension adjustment device for film conveying in a feed packaging line as described in claim 1, characterized in that, include: S1. Real-time acquisition of the first flow sensing data of the gas flow meter (620) on the connecting pipeline (500); S2. Real-time acquisition of the first pressure sensing data of the pressure sensor (630) on the connecting pipeline (500); S3. Calculate the first real-time fluid resistance value based on the first flow sensing data and the first pressure sensing data; S4. Obtain a preset reference fluid impedance model and compare the first real-time fluid impedance value with the reference fluid impedance model; S5. Based on the comparison results, the first real-time film tension state data is obtained.

7. The control method according to claim 6, characterized in that, The step S5 is followed by: S601. Obtain the rate of change and high-frequency component of the first real-time fluid impedance value within a set time interval; S602. When the first real-time fluid impedance value is lower than the first threshold of the reference fluid impedance model and is accompanied by high-frequency fluctuations, it is determined that the thin film is in a relaxed flutter state. S603. Control the gas supply and detection system (600) to switch to negative pressure adsorption mode, and use negative pressure to adsorb the film onto the surface of the drive roller (310).

8. The control method according to claim 6, characterized in that, The step S5 is followed by: S701. When the first real-time fluid impedance value is higher than the second threshold of the reference fluid impedance model and there is no fluctuation, it is determined that the film is in an over-tensioned state. S702, Control the gas supply and detection system (600) to inject high-pressure pulsed gas flow into the connecting pipeline (500); S703. The high-pressure pulsed airflow forms an air cushion on the surface of the drive roller (310), forcing the film to slip slightly to release tension.

9. The control method according to claim 6, characterized in that, The step S5 is followed by: S801, Receive emergency stop command from external packaging machine; S802, control the gas supply and detection system (600) to cut off the gas supply and apply negative pressure to lock the film on the surface of the drive roller (310); S803. The film is stopped from being transported by using the braking torque of the drive motor (330) in conjunction with the friction force on the surface of the drive roller (310).

Images