Method for regulating axial air pressure distribution of vacuum suction roll

Abstract

This invention discloses a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller. First, a digital model of the vacuum adsorption roller is accurately constructed using reverse modeling technology combined with 3D modeling software. Then, this model is imported into CFD mesh generation software for fluid domain extraction and mesh division. After refining the mesh in key areas, environmental parameters are configured in computational fluid dynamics software. Next, the boundary conditions of the inlet and outlet under actual working conditions are set. The internal air pressure distribution is obtained through numerical simulation calculation. The simulation results are analyzed to identify the air pressure distribution areas. Based on the analysis results, the area and layout of the air inlets in each axial region are adjusted to balance the air intake and ensure uniform air pressure distribution. Finally, the effectiveness of the adjustment scheme is verified in an actual production environment, and the size and layout of the air inlets are optimized based on measured data until the predetermined air pressure uniformity standard is achieved. This method achieves precise control and optimization of the axial air pressure distribution of the vacuum adsorption roller.

Description

Technical Field

[0001] This invention relates to the field of vacuum adsorption roller technology, and in particular to a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller. Background Technology

[0002] Vacuum adsorption rollers are an indispensable component in modern industrial production, especially in industries such as papermaking, printing, and packaging. Primarily used as dewatering elements, they operate in the wire and press sections of paper machines, utilizing the negative pressure they generate to draw moisture from the paper sheet or felt, thereby increasing paper dryness and reducing energy consumption required for drying. Furthermore, vacuum adsorption rollers are also used to maintain the stability and tension control of roll materials (such as paper and plastic film) during processing, ensuring that the material does not shift or deform during processing.

[0003] However, in practical applications, traditional vacuum adsorption rollers have some limitations, especially in terms of uniform adsorption of roll materials and edge control. When the roll material passes through the vacuum adsorption roller, uneven air pressure distribution may lead to insufficient adsorption in some areas of the roll material, resulting in problems such as curling and wrinkling, which seriously affect the quality and flatness of the product. These problems are particularly prominent in high-speed continuous production environments, which not only reduce production efficiency but also increase the scrap rate.

[0004] Therefore, this application proposes a method for uniformizing the axial air pressure distribution of a vacuum adsorption roller, aiming to provide a more stable and reliable roll material processing solution to meet the growing demand for high-quality product manufacturing. Summary of the Invention

[0005] The purpose of this invention is to provide a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller. By intelligently controlling the air pressure in each area, it ensures uniform adsorption of the roll material, prevents edge curling, and improves product quality and production efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller, comprising the following steps:

[0007] S1. Establish a three-dimensional digital model of the vacuum adsorption roller:

[0008] The actual size and structural information of the vacuum adsorption roller are obtained by using reverse modeling technology. Based on the obtained actual size and structural information, a three-dimensional digital model that accurately corresponds to the real vacuum adsorption roller is established using three-dimensional modeling software.

[0009] S2. Import into computational fluid dynamics software:

[0010] Import the 3D model established in step S1 into the CFD mesh drawing software, extract the fluid domain and complete the mesh generation, refine the mesh in the key areas, and then import the computational mesh into the computational fluid dynamics software and configure the environmental parameters.

[0011] S3. Set the working condition boundaries and perform simulation calculations:

[0012] Given the inlet boundary conditions and the outlet boundary conditions of the vacuum adsorption roller during actual operation, numerical simulation calculations are performed in computational fluid dynamics software based on the above boundary conditions to obtain the distribution of air pressure inside the roller.

[0013] S4. Analyze the air pressure distribution of the vacuum adsorption roller:

[0014] From the simulation results of step S3, analyze the air pressure distribution data at various points on the surface of the vacuum adsorption roller, and identify areas with excessively low or high air pressure, especially areas with a large difference in air pressure between the two ends and the middle of the roller axis.

[0015] S5. Adjust the area and layout of the air inlet holes of the vacuum adsorption roller:

[0016] Based on the analysis results of step S4, the area and layout of the air inlets in different axial regions are adjusted to regulate the air intake in each region until a uniform axial air pressure distribution is obtained.

[0017] S6. Experimental verification and optimization:

[0018] In actual production, according to the adjustment plan in step S5, the area and layout of the air inlets in different axial regions of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial region before and after adjustment, the parameters are further optimized by analyzing and using the feedback results until the uniformity of air pressure distribution reaches the predetermined requirements. Finally, the size and layout of the air inlets in each region are determined.

[0019] Preferably, step S1 specifically includes the following steps:

[0020] (1) Use a three-dimensional laser scanning system to perform an all-round scan of the vacuum adsorption roller in a stationary state to obtain high-density point cloud data including the outer surface and end face of the roller.

[0021] (2) Import the above point cloud data into reverse modeling software and use the automatic surface fitting algorithm to reconstruct the three-dimensional solid model of the overall outer surface of the roller.

[0022] (3) Based on the scanned point cloud data, combined with the design drawings and dimensional parameters of the vacuum adsorption roller, establish the internal cavity and air passage structure model, and accurately locate the spatial position and size of each air inlet and exhaust port on the three-dimensional model;

[0023] (4) Perform parametric editing on the reconstructed overall three-dimensional solid model to ensure that the design dimensions of the roller body radius, length, air inlet and exhaust hole can be adjusted as needed.

[0024] Preferably, step S2 specifically includes the following steps:

[0025] (1) Import the three-dimensional model established in step S1 into the CFD mesh generation software and extract the fluid domain space of the gas flow inside the vacuum adsorption roller.

[0026] (2) Mesh the fluid domain using hexahedral or tetrahedral meshing, and refine the mesh for the air inlet and exhaust ports. Set the mesh unit size to be within the range of 0.1mm-2mm, and ensure that the orthogonality and twist in the mesh quality parameters are not less than 0.3 and not greater than 0.85.

[0027] (3) Import the completed mesh into the computational fluid dynamics software, and set the physical properties of the fluid medium. Set the working medium to air and configure the air density to 1.225 kg / m³. 3 The dynamic viscosity was set to 1.789 × 10⁻⁶. -5 Pa·s, the operating temperature is defined as the standard atmospheric temperature;

[0028] (4) The standard k-ε turbulence model is adopted, the turbulence intensity is set to 5%, the pressure-based solver is selected, and the SIMPLE pressure-velocity coupling algorithm is used to achieve effective coupling of the pressure field and the velocity field through iteration, thereby improving the convergence and computational stability of the numerical simulation.

[0029] (5) Set the momentum equation and pressure term to a second-order upwind scheme, the pressure term to the PRESTO! format, and the turbulent kinetic energy and dissipation rate to a second-order upwind scheme. Configure the convergence residual control value to 1×10. -4 ;

[0030] (6) By setting 3-5 different grid densities for comparative calculation, the variation of pressure and velocity at key locations with the number of grids is monitored, and the final grid division scheme is determined so that the calculation results are not affected by the number of grids.

[0031] (7) Set several monitoring points in the axial direction of the vacuum adsorption roller according to the number of air inlets, wherein each monitoring point covers the same number of air inlets, so as to realize real-time monitoring of the calculation process.

[0032] Preferably, in step S3, the inlet pressure is set to standard atmospheric pressure, the outlet pressure is set to a stable negative pressure value within the range of -30kPa to -50kPa, and no-slip boundary conditions are set for all solid walls to ensure that the boundary conditions are consistent with the actual working conditions.

[0033] Preferably, step S4 specifically includes the following steps:

[0034] (1) Extract the pressure distribution data along the axial direction on the surface of the vacuum adsorption roller, establish the pressure-axial position relationship curve, calculate the average pressure value and pressure fluctuation range of each region, and determine the non-uniformity of the axial pressure distribution.

[0035] (2) Quantitatively analyze the pressure difference between the two ends and the middle area of ​​the roller, calculate the pressure gradient between adjacent areas, identify the transition area with drastic pressure changes, and determine the area that needs to be adjusted.

[0036] (3) Analyze the flow distribution at each air inlet, establish the correspondence between the air inlet area and the local pressure, and determine the target pressure value and allowable pressure fluctuation range for each area in combination with the production process requirements.

[0037] Preferably, step S5 specifically includes the following steps:

[0038] (1) Based on the analysis results of step S4, a parametric design method is adopted to establish a response relationship model between the air inlet area and local pressure, and to determine the adjustment scheme and optimization target of the air inlet in each region.

[0039] (2) Based on the unevenness of air pressure distribution, formulate regional adjustment plans. For areas with low pressure, adjust gradually by reducing the area of ​​the air inlet by 5% or by reducing the number of air inlets to increase local pressure. For areas with high pressure, adjust gradually by increasing the area of ​​the air inlet by 5% or by increasing the number of air inlets to reduce local pressure. Record the changes in local pressure after each adjustment and ensure that the pressure changes are within a reasonable range to gradually achieve balanced pressure distribution.

[0040] (3) Verify the adjusted scheme using numerical simulation methods. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions to ensure that the simulation conditions are consistent with the previous analysis, obtain the adjusted axial pressure distribution curve through simulation calculation, extract the pressure mean and fluctuation range of each region, and evaluate the adjustment effect.

[0041] (4) Based on the simulation verification results, if the pressure distribution still does not reach the uniformity target, further optimize and adjust the scheme in combination with the local pressure deviation value. The optimization content includes adjusting the air inlet area or the number of air inlets. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range.

[0042] (5) Determine the optimal scheme for the air intake area and the layout of the air intake position.

[0043] Preferably, step S6 specifically includes the following steps:

[0044] (1) Modify the air inlet hole on the actual vacuum adsorption roller according to the optimized scheme;

[0045] (2) Install a digital pressure sensor array, and arrange no less than 10 pressure measuring points evenly along the roller axis. Use a data acquisition system to record the pressure value of each measuring point in real time, and monitor continuous operation conditions for no less than 8 hours.

[0046] (3) Analyze and process the collected pressure data. First, filter and remove outliers from the raw data. Calculate the average value, standard deviation and fluctuation range of the pressure at each measuring point. Then, establish the axial pressure distribution curve and use the least squares method to fit the curve. Calculate the root mean square error of the fitted curve. Next, evaluate the uniformity of the axial pressure distribution and calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two ends of the axial direction and the middle area within ±8%, and control the pressure fluctuation coefficient below 0.1. If the test results show that the pressure distribution in some areas does not meet the uniformity requirements, return to step S5 to make targeted adjustments to the air inlet parameters of the corresponding area according to the direction and magnitude of the pressure deviation. The adjustment range is determined according to 20%-30% of the pressure deviation. Repeat the optimization process until all indicators reach the set target and determine the final air inlet size and layout.

[0047] Compared with existing technologies, the advantages of this invention are as follows: This method, through a complete process design and combined with advanced modeling, numerical simulation, and experimental optimization techniques, achieves precise adjustment of the air pressure distribution of the vacuum adsorption roller. Step S1 uses reverse modeling technology to obtain the actual size and structural information of the vacuum adsorption roller, and establishes an accurate three-dimensional digital model using three-dimensional modeling software, laying the foundation for subsequent analysis; Step S2 imports the three-dimensional model into CFD mesh rendering software, extracts the fluid domain, and performs high-quality mesh generation, refining the mesh for key areas such as the air inlet and exhaust ports, thereby ensuring the accuracy and detail of the simulation results. Simultaneously, the optimized mesh is imported into computational fluid dynamics software, and suitable fluid media and boundary conditions are configured to provide an accurate physical environment for numerical simulation; Step S3 sets the boundary parameters of the air inlet and exhaust ports according to the actual working conditions of the vacuum adsorption roller. Step S4 involves obtaining the internal air pressure distribution through numerical simulation; using the simulation results, analyzing the non-uniformity of the air pressure distribution on the roller surface, identifying areas with excessively low or high air pressure, especially areas with significant differences between the two ends and the middle of the axial direction, providing a basis for subsequent adjustments; Step S5 involves adjusting the area and layout of the air inlets in each axial region based on the analysis results, gradually optimizing the air intake in different regions, and ensuring uniform air pressure distribution through repeated simulations and verifications; Step S6 involves verifying the optimization effect in an actual production environment, further adjusting the air inlet parameters based on the measured air pressure data, ensuring that axial pressure fluctuations are controlled within a reasonable range, and finally determining a stable and uniform air inlet size and layout scheme.

[0048] This method incorporates digital, visualization, and quantitative analysis techniques, enabling rapid identification of air pressure distribution issues and gradual homogenization of axial air pressure through iterative optimization. Finally, through on-site experimental verification and feedback, the optimal inlet size and layout can be determined, significantly improving the performance stability and working efficiency of the vacuum adsorption roller. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 This is a flowchart of the present invention;

[0051] Figure 2 This is a pressure distribution diagram of the vacuum adsorption roller before adjustment in this invention;

[0052] Figure 3 This is a pressure distribution diagram of the vacuum adsorption roller after adjustment according to the present invention;

[0053] Figure 4 This is a comparison chart of airflow data at different positions of the air intake before and after adjustment. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] Example 1: As shown in the figure, a method for uniformizing the axial air pressure distribution of a vacuum adsorption roller includes the following steps:

[0056] S1. Establish a three-dimensional digital model of the vacuum adsorption roller:

[0057] The actual size and structural information of the vacuum adsorption roller are obtained by using reverse modeling technology. Based on the obtained actual size and structural information, a three-dimensional digital model that accurately corresponds to the real vacuum adsorption roller is established using three-dimensional modeling software.

[0058] S2. Import into computational fluid dynamics software:

[0059] Import the 3D model established in step S1 into the CFD mesh drawing software, extract the fluid domain and complete the mesh generation, refine the mesh in the key areas, and then import the computational mesh into the computational fluid dynamics software and configure the environmental parameters.

[0060] S3. Set the working condition boundaries and perform simulation calculations:

[0061] Given the inlet boundary conditions and the outlet boundary conditions of the vacuum adsorption roller during actual operation, numerical simulation calculations are performed in computational fluid dynamics software based on the above boundary conditions to obtain the distribution of air pressure inside the roller.

[0062] S4. Analyze the air pressure distribution of the vacuum adsorption roller:

[0063] From the simulation results of step S3, analyze the air pressure distribution data at various points on the surface of the vacuum adsorption roller, and identify areas with excessively low or high air pressure, especially areas with a large difference in air pressure between the two ends and the middle of the roller axis.

[0064] S5. Adjust the area and layout of the air inlet holes of the vacuum adsorption roller:

[0065] Based on the analysis results of step S4, the area and layout of the air inlets in different axial regions are adjusted to regulate the air intake in each region until a uniform axial air pressure distribution is obtained.

[0066] S6. Experimental verification and optimization:

[0067] In actual production, according to the adjustment plan in step S5, the area and layout of the air inlets in different axial regions of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial region before and after adjustment, the parameters are further optimized by analyzing and using the feedback results until the uniformity of air pressure distribution reaches the predetermined requirements. Finally, the size and layout of the air inlets in each region are determined.

[0068] Preferably, step S1 specifically includes the following steps:

[0069] (1) Use a three-dimensional laser scanning system to perform an all-round scan of the vacuum adsorption roller in a stationary state to obtain high-density point cloud data including the outer surface and end face of the roller.

[0070] (2) Import the above point cloud data into reverse modeling software and use the automatic surface fitting algorithm to reconstruct the three-dimensional solid model of the overall outer surface of the roller.

[0071] (3) Based on the scanned point cloud data, combined with the design drawings and dimensional parameters of the vacuum adsorption roller, establish the internal cavity and air passage structure model, and accurately locate the spatial position and size of each air inlet and exhaust port on the three-dimensional model;

[0072] (4) Perform parametric editing on the reconstructed overall three-dimensional solid model to ensure that the design dimensions of the roller body radius, length, air inlet and exhaust hole can be adjusted as needed.

[0073] This optimized reverse modeling method provides an extremely accurate and flexible technical path for the digital reconstruction of vacuum adsorption rollers. By employing a 3D laser scanning system for comprehensive high-density point cloud data acquisition, this method can capture the geometric features of the vacuum adsorption roller, including its complex external surface morphology and fine structural details, overcoming the limitations of traditional manual measurement methods. Utilizing advanced automatic surface fitting algorithms, the point cloud data can be quickly converted into an accurate 3D solid model, preserving not only the geometric accuracy of the original parts but also significantly improving modeling efficiency. More importantly, by combining scanning data, design drawings, and dimensional parameters, this method can accurately reconstruct the internal cavity and air passage structure, and precisely locate the spatial position and size of each air inlet and exhaust port, laying a solid foundation for subsequent air pressure distribution simulation and optimization. Furthermore, parametric editing of the reconstructed model allows key parameters such as roller radius, length, air inlets, and exhaust ports to be dynamically adjusted according to actual process requirements, greatly improving the accuracy and convenience of the design and creating significant advantages for subsequent numerical simulation and performance optimization.

[0074] Preferably, step S2 specifically includes the following steps:

[0075] (1) Import the three-dimensional model established in step S1 into the CFD mesh generation software and extract the fluid domain space of the gas flow inside the vacuum adsorption roller.

[0076] (2) Mesh the fluid domain using hexahedral or tetrahedral meshing, and refine the mesh for the air inlet and exhaust ports. Set the mesh unit size to be within the range of 0.1mm-2mm, and ensure that the orthogonality and twist in the mesh quality parameters are not less than 0.3 and not greater than 0.85.

[0077] (3) Import the completed mesh into the computational fluid dynamics software, and set the physical properties of the fluid medium. Set the working medium to air and configure the air density to 1.225 kg / m³. 3 The dynamic viscosity was set to 1.789 × 10⁻⁶. -5 Pa·s, the operating temperature is defined as the standard atmospheric temperature;

[0078] (4) The standard k-ε turbulence model is adopted, the turbulence intensity is set to 5%, the pressure-based solver is selected, and the SIMPLE pressure-velocity coupling algorithm is used to achieve effective coupling of the pressure field and the velocity field through iteration, thereby improving the convergence and computational stability of the numerical simulation.

[0079] (5) Set the momentum equation and pressure term to a second-order upwind scheme, the pressure term to the PRESTO! format, and the turbulent kinetic energy and dissipation rate to a second-order upwind scheme. Configure the convergence residual control value to 1×10⁻⁶. -4 ;

[0080] (6) By setting 3-5 different grid densities for comparative calculation, the variation of pressure and velocity at key locations with the number of grids is monitored, and the final grid division scheme is determined so that the calculation results are not affected by the number of grids.

[0081] (7) Set several monitoring points in the axial direction of the vacuum adsorption roller according to the number of air inlets, wherein each monitoring point covers the same number of air inlets, so as to realize real-time monitoring of the calculation process.

[0082] In the above steps, by extracting the fluid domain space of the gas flow inside the vacuum adsorption roller, a geometric foundation is laid for subsequent simulations, ensuring that the numerical simulation can accurately reflect the actual physical space. The mesh generation stage employs a hybrid hexahedral or tetrahedral mesh, with focused refinement of key areas such as the air inlet and outlet. Mesh cell sizes are set within the range of 0.1-2 mm, and by strictly controlling mesh quality parameters, such as orthogonality not less than 0.3 and twist not greater than 0.85, the accuracy and reliability of the numerical simulation can be significantly improved.

[0083] In terms of physical parameter configuration, the air density, dynamic viscosity, and operating temperature were precisely set, providing accurate physical boundary conditions for subsequent numerical simulations. Choosing the standard k-ε turbulence model and setting a 5% turbulence intensity is a typical method for simulating complex internal flows, effectively capturing turbulence characteristics. Employing a pressure-based solver and the SIMPLE pressure-velocity coupling algorithm, effective coupling of the pressure and velocity fields was achieved through iteration, improving not only the convergence of the numerical simulation but also enhancing computational stability.

[0084] For numerical discretization and solution, a second-order upwind scheme was chosen to discretize the momentum equation and pressure term, and the PRESTO! pressure discretization scheme was employed. These choices significantly improve numerical accuracy and computational stability. By setting the convergence residual control value to 1×10⁻⁴, high accuracy and reliability of the calculation results are ensured. To further verify the reliability of the mesh generation, the calculation results of 3-5 different mesh densities were compared to analyze the variation patterns of pressure and velocity at key locations. Finally, the optimal mesh generation scheme that ensures the calculation results are unaffected by the number of meshes was selected.

[0085] Each monitoring point covers the same number of exhaust vents. This monitoring method not only enables precise monitoring of the calculation process, but also directly correlates the air pressure and flow characteristics around each exhaust vent, providing a more accurate data basis for subsequent pressure distribution uniformity adjustment.

[0086] Preferably, in step S3, the inlet pressure is set to standard atmospheric pressure, the outlet pressure is set to a stable negative pressure value within the range of -30kPa to -50kPa, and no-slip boundary conditions are set for all solid walls to ensure that the boundary conditions are consistent with the actual working conditions.

[0087] This boundary condition setting achieves an accurate simulation of the actual working environment of the vacuum adsorption roller. Specifically, the inlet pressure is set to standard atmospheric pressure (approximately 101.325 kPa) to simulate the inlet state under normal pressure; the exhaust pressure is set within a negative pressure range of -30 kPa to -50 kPa to accurately reflect the actual negative pressure working state of the vacuum adsorption roller. For example, for a vacuum adsorption roller on a printing press, if its working negative pressure is typically -40 kPa, then the exhaust pressure can be precisely set to -40 kPa during simulation. The no-slip boundary condition ensures that the airflow behavior on the model surface is consistent with the actual physical process, allowing the numerical simulation to approximate the real working conditions as closely as possible, thus improving the reliability and accuracy of the simulation results.

[0088] Preferably, step S4 specifically includes the following steps:

[0089] (1) Extract the pressure distribution data along the axial direction on the surface of the vacuum adsorption roller, establish the pressure-axial position relationship curve, calculate the average pressure value and pressure fluctuation range of each region, and determine the non-uniformity of the axial pressure distribution.

[0090] (2) Quantitatively analyze the pressure difference between the two ends and the middle area of ​​the roller, calculate the pressure gradient between adjacent areas, identify the transition area with drastic pressure changes, and determine the area that needs to be adjusted.

[0091] (3) Analyze the flow distribution at each air inlet, establish the correspondence between the air inlet area and the local pressure, and determine the target pressure value and allowable pressure fluctuation range for each area in combination with the production process requirements.

[0092] This step is crucial for regulating the uniformity of air pressure distribution on the vacuum adsorption roller. Through systematic data extraction and analysis, the characteristics of air pressure distribution are precisely quantified. First, by extracting the pressure distribution data along the axial direction on the surface of the vacuum adsorption roller, a pressure-axial position relationship curve is established. This not only visually displays the trend of air pressure variation along the axial direction, but also quantitatively assesses the non-uniformity of axial pressure distribution by calculating the average pressure value and pressure fluctuation range of each region.

[0093] Further quantitative analysis of the pressure difference between the two ends and the middle region of the roller allows for the precise identification of transitional areas with drastic pressure changes by calculating the pressure gradient between adjacent regions. This analysis not only accurately locates the specific positions of pressure unevenness but also provides a precise reference for subsequent adjustment of the air inlet. In practical engineering, the pressure gradient between the end region and the middle region may be as high as 20-30 kPa / 100 mm. This significant pressure change will directly affect the working performance of the vacuum adsorption roller.

[0094] Finally, by analyzing the flow distribution at each air inlet, a correspondence between the air inlet area and local pressure is established. Combined with specific production process requirements, the target pressure value and allowable pressure fluctuation range for each region can be accurately determined. For example, for a vacuum adsorption roller in a precision printing machine, the pressure fluctuation in each axial region may need to be controlled within ±5%, with the target pressure value for the middle region set at -40 kPa, and the end region allowed to fluctuate within the range of -35 kPa to -45 kPa.

[0095] Preferably, step S5 specifically includes the following steps:

[0096] (1) Based on the analysis results of step S4, a parametric design method is adopted to establish a response relationship model between the air inlet area and local pressure, and to determine the adjustment scheme and optimization target of the air inlet in each region.

[0097] (2) Based on the unevenness of air pressure distribution, formulate regional adjustment plans. For areas with low pressure, adjust gradually by reducing the area of ​​the air inlet by 5% or by reducing the number of air inlets to increase local pressure. For areas with high pressure, adjust gradually by increasing the area of ​​the air inlet by 5% or by increasing the number of air inlets to reduce local pressure. Record the changes in local pressure after each adjustment and ensure that the pressure changes are within a reasonable range to gradually achieve balanced pressure distribution.

[0098] (3) Verify the adjusted scheme using numerical simulation methods. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions to ensure that the simulation conditions are consistent with the previous analysis, obtain the adjusted axial pressure distribution curve through simulation calculation, extract the pressure mean and fluctuation range of each region, and evaluate the adjustment effect.

[0099] (4) Based on the simulation verification results, if the pressure distribution still does not reach the uniformity target, further optimize and adjust the scheme in combination with the local pressure deviation value. The optimization content includes adjusting the air inlet area or the number of air inlets. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range.

[0100] (5) Determine the optimal scheme for the air intake area and the layout of the air intake position.

[0101] In the above steps, a response model between the inlet area and local pressure is established using a parametric design method, laying the foundation for subsequent regulation. To address the uneven pressure distribution, a regional optimization scheme based on incremental adjustment is proposed. For areas with low pressure, the local pressure is increased by reducing the inlet area by 5% or decreasing the number of inlets; for areas with high pressure, the local pressure is decreased by increasing the inlet area by 5% or increasing the number of inlets. This gradual adjustment strategy ensures that each adjustment is within a controllable range, avoiding drastic pressure fluctuations.

[0102] Numerical simulations performed in computational fluid dynamics software can accurately track changes in pressure distribution with each adjustment. For example, in a 1500mm long vacuum adsorption roller, the pressure in the end region may fluctuate within ±15% initially. After multiple iterative adjustments, the pressure fluctuation can be controlled within ±5%. If the simulation results show that the pressure distribution still has not reached the homogenization target, the scheme will continue to iteratively optimize based on the local pressure deviation value, adjusting the area or number of air inlets to form a closed-loop optimization iteration process.

[0103] This iterative optimization method based on numerical simulation can not only accurately describe the pressure distribution characteristics, but also achieve a high degree of uniformity in the axial air pressure distribution of the vacuum adsorption roller through systematic and incremental adjustments. The final determined air inlet area and layout scheme meet specific process requirements.

[0104] Preferably, step S6 specifically includes the following steps:

[0105] (1) Modify the air inlet hole on the actual vacuum adsorption roller according to the optimized scheme;

[0106] (2) Install a digital pressure sensor array, and arrange no less than 10 pressure measuring points evenly along the roller axis. Use a data acquisition system to record the pressure value of each measuring point in real time, and monitor continuous operation conditions for no less than 8 hours.

[0107] (3) Analyze and process the collected pressure data. First, filter and remove outliers from the raw data. Calculate the average value, standard deviation and fluctuation range of the pressure at each measuring point. Then, establish the axial pressure distribution curve and use the least squares method to fit the curve. Calculate the root mean square error of the fitted curve. Next, evaluate the uniformity of the axial pressure distribution and calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two ends of the axial direction and the middle area within ±8%, and control the pressure fluctuation coefficient below 0.1. If the test results show that the pressure distribution in some areas does not meet the uniformity requirements, return to step S5 to make targeted adjustments to the air inlet parameters of the corresponding area according to the direction and magnitude of the pressure deviation. The adjustment range is determined according to 20%-30% of the pressure deviation. Repeat the optimization process until all indicators reach the set target and determine the final air inlet size and layout.

[0108] This step is the final verification and fine-tuning stage for the uniformity adjustment of air pressure distribution on the vacuum adsorption roller. Through systematic testing and data analysis under actual working conditions, the engineering verification of the numerical simulation results is achieved. Based on the previous optimization plan, the air inlet of the vacuum adsorption roller was modified to lay the foundation for accurate testing. A digital pressure sensor array was used to evenly distribute pressure measurement points along the roller axis and to conduct continuous monitoring for up to 8 hours. This design can not only capture the pressure distribution characteristics under steady-state operation, but also eliminate the random influence of short-term fluctuations.

[0109] Rigorous scientific methods were employed in the data processing stage, ensuring data reliability through filtering and outlier removal. The least squares method was used to fit the axial pressure distribution curve, the root mean square error was calculated, and the pressure distribution uniformity was evaluated from multiple dimensions. Specific evaluation indicators included the pressure gradient and coefficient of variation between adjacent measuring points. The pressure difference between the two ends and the middle region of the axial direction was required to be controlled within ±8%, and the pressure fluctuation coefficient was required to be below 0.1. For example, in a 1500mm long vacuum adsorption roller, if the initial pressure fluctuation in the end region might be as high as ±15%, after optimization, it could be controlled within ±6%.

[0110] If the test results show that the pressure distribution in some areas still does not meet the uniformity requirements, this method designs a closed-loop iterative optimization mechanism. Based on the direction and magnitude of the pressure deviation, it returns to the inlet parameter adjustment step, using 20%-30% of the pressure deviation as the adjustment range to ensure that each optimization is precise and controllable. This iterative optimization method based on measured data can ultimately determine the optimal inlet size and layout, providing a systematic, data-driven adjustment method for optimizing the performance of vacuum adsorption rollers.

[0111] Example 2: Initial Analysis of Vacuum Adsorption Rollers in a Paper Mill

[0112] First, a 3D laser scanning system is used to scan the vacuum adsorption roller from all directions to obtain high-density point cloud data, including the outer surface and end face of the roller. Then, SolidWorks modeling software is used to reconstruct the 3D solid model of the roller, and the internal cavity and air passage structure model are established in conjunction with the design drawings.

[0113] The reconstructed 3D model was imported into CFD mesh generation software to extract and mesh the fluid domain of gas flow inside the vacuum adsorption roller, with mesh refinement performed in key areas. After importing into the computational fluid dynamics software, environmental parameters were configured, including setting the working medium to air with a density of 1.225 kg / m³. 3 The dynamic viscosity is 1.789 × 10⁻⁶. -5 Pa·s, using the standard k-ε turbulence model.

[0114] The inlet pressure was set to standard atmospheric pressure, and the outlet pressure was set to a stable negative pressure of -40 kPa. Numerical simulation was performed to obtain the initial axial pressure distribution of the vacuum adsorption roller. The results show that the axial pressure distribution is uneven, with areas of high and low pressure, especially showing significant differences between the ends and the middle of the roller.

[0115] Based on the above analysis results, a parametric design method was used to adjust the area and layout of the air inlets. For the pressure distribution data, the vacuum adsorption roller was divided into 19 monitoring positions, with each monitoring point covering 11 air inlets. Initially, the volumetric flow rate and average flow rate per inlet at each monitoring point are shown in Table 1.

[0116] Table 1 shows the volumetric flow rate and average flow rate per orifice at each monitoring point under the initial conditions.

[0117]

[0118]

[0119] The pressure distribution calculated using the original model is shown in the attached instruction manual. Figure 2 As shown.

[0120] The adjustment strategy includes reducing the number or area of ​​air inlets in high-pressure areas and increasing the number or area of ​​air inlets in low-pressure areas. The distribution of the number of blocked air inlets after adjustment according to the optimization plan is shown in Table 2.

[0121] Table 2 Distribution of the number of plugs

[0122]

[0123]

[0124] After optimization, numerical simulations were performed again to obtain the adjusted pressure distribution curve. The optimized volumetric flow rate and average flow rate per orifice at each monitoring point are shown in Table 3.

[0125] Table 3. Optimized volumetric flow rate and average flow rate per orifice at each monitoring point.

[0126]

[0127]

[0128] The pressure distribution calculated by the optimized model is shown in the attached figure. Figure 3 As shown, attached Figure 4 To compare the airflow data at different intake positions before and after adjustment, see the attached chart. Figure 3 It can be seen that there are significant differences in the flow rate of the air inlets at different locations. Initially, the flow rate is higher at both ends of the roller and lower in the middle area, which directly leads to uneven axial air pressure. After optimization and adjustment, the flow rate difference is significantly reduced, and the average flow rate of each monitoring point is more similar, indicating that the air pressure distribution has been effectively improved.

[0129] In the actual production environment, the vacuum adsorption roller is modified according to the optimized air inlet layout, and no fewer than 10 digital pressure sensor arrays are installed, evenly distributed along the axial direction. A data acquisition system is used to record the pressure values ​​at each measuring point, and the monitoring time is no less than 8 hours.

[0130] The collected data were analyzed and processed to calculate the average pressure and fluctuation range at each measuring point. The variance of the optimized pressure distribution was reduced from the initial 5.25518 × 10⁻⁶. -8 Reduced to 4.06042×10 -8 This indicates a more uniform air pressure distribution. The pressure gradient between adjacent measuring points is controlled within ±8%, and the pressure fluctuation coefficient is less than 0.1.

[0131] If some areas still do not achieve the homogenization target, the air intake parameters are further optimized based on the feedback results. The adjustment and verification process is repeated to finally determine the size and layout of the air intakes in each area.

[0132] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller, characterized in that: Includes the following steps, S1. Establish a three-dimensional digital model of the vacuum adsorption roller: The actual size and structural information of the vacuum adsorption roller are obtained by using reverse modeling technology. Based on the obtained actual size and structural information, a three-dimensional digital model that accurately corresponds to the real vacuum adsorption roller is established using three-dimensional modeling software. S2. Import into computational fluid dynamics software: Import the 3D model established in step S1 into the CFD mesh generation software, extract the fluid domain and complete the mesh generation, refine the mesh in the key areas, and then import the computational mesh into the computational fluid dynamics software and configure the environmental parameters. S3. Set the working condition boundaries and perform simulation calculations: Given the inlet boundary conditions and the outlet boundary conditions of the vacuum adsorption roller during actual operation, numerical simulation calculations are performed in computational fluid dynamics software based on the above boundary conditions to obtain the distribution of air pressure inside the roller. S4. Analyze the air pressure distribution of the vacuum adsorption roller: From the simulation results of step S3, analyze the air pressure distribution data at each point on the surface of the vacuum adsorption roller to identify areas with excessively low or high air pressure. S5. Adjust the area and layout of the air inlet holes of the vacuum adsorption roller: Based on the analysis results of step S4, the area and layout of the air inlets in different axial regions are adjusted to regulate the air intake in each region until a uniform axial air pressure distribution is obtained. S6. Experimental verification and optimization: In actual production, according to the adjustment plan in step S5, the area and layout of the air inlets in different axial regions of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial region before and after adjustment, the parameters are further optimized by analyzing and using the feedback results until the uniformity of air pressure distribution reaches the predetermined requirements. Finally, the size and layout of the air inlets in each region are determined.

2. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: Step S1 specifically includes the following steps: (1) Use a three-dimensional laser scanning system to perform an all-round scan of the vacuum adsorption roller in a stationary state to obtain high-density point cloud data including the outer surface and end face of the roller. (2) Import the above point cloud data into reverse modeling software and use the automatic surface fitting algorithm to reconstruct the three-dimensional solid model of the overall outer surface of the roller. (3) Based on the scanned point cloud data, combined with the design drawings and dimensional parameters of the vacuum adsorption roller, establish the internal cavity and air passage structure model, and accurately locate the spatial position and size of each air inlet and exhaust port on the three-dimensional model; (4) Perform parametric editing on the reconstructed overall three-dimensional solid model to ensure that the design dimensions of the roller body radius, length, air inlet and exhaust hole are adjusted as needed.

3. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: Step S2 specifically includes the following steps: (1) Import the three-dimensional model established in step S1 into the CFD mesh generation software and extract the fluid domain space of the gas flow inside the vacuum adsorption roller. (2) Mesh the fluid domain using hexahedral or tetrahedral meshing, and refine the mesh for the air inlet and exhaust ports. Set the mesh unit size to be within the range of 0.1mm-2mm, and ensure that the orthogonality and twist in the mesh quality parameters are not less than 0.3 and not greater than 0.

85. (3) Import the completed mesh into the computational fluid dynamics software, and set the physical properties of the fluid medium. Set the working medium to air, with an air density of 1.225 kg / m³ and a dynamic viscosity of 1.789 × 10⁻⁶. -5 Pa·s, the operating temperature is defined as the standard atmospheric temperature; (4) The standard k-ε turbulence model is adopted, the turbulence intensity is set to 5%, the pressure-based solver is selected, and the SIMPLE pressure-velocity coupling algorithm is used to achieve effective coupling of the pressure field and the velocity field through iteration, thereby improving the convergence and computational stability of the numerical simulation. (5) Set the momentum equation and pressure term to a second-order upwind scheme, the pressure term to the PRESTO! scheme, and the turbulent kinetic energy and dissipation rate to a second-order upwind scheme. Configure the convergence residual control value to be 1×10⁻⁶. -4 ; By setting 3-5 different grid densities for comparative calculations, the variation of pressure and velocity at key locations with the number of grids is monitored to determine the final grid division scheme to ensure that the calculation results are not affected by the number of grids. Several monitoring points are set along the axial direction of the vacuum adsorption roller according to the number of air inlets, with each monitoring point covering the same number of air inlets, so as to realize real-time monitoring of the calculation process.

4. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: In step S3, the inlet pressure is set to standard atmospheric pressure, the exhaust port is set to a stable negative pressure value within the range of -30kPa to -50kPa, and no-slip boundary conditions are set for all solid walls to ensure that the boundary conditions are consistent with the actual working conditions.

5. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: Step S4 specifically includes the following steps: (1) Extract the pressure distribution data along the axial direction on the surface of the vacuum adsorption roller, establish the pressure-axial position relationship curve, calculate the average pressure value and pressure fluctuation range of each region, and determine the non-uniformity of the axial pressure distribution. (2) Quantitatively analyze the pressure difference between the two ends and the middle area of ​​the roller, calculate the pressure gradient between adjacent areas, identify the transition area with drastic pressure changes, and determine the area that needs to be adjusted. (3) Analyze the flow distribution at each air inlet, establish the correspondence between the air inlet area and the local pressure, and determine the target pressure value and allowable pressure fluctuation range for each area in combination with the production process requirements.

6. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: Step S5 specifically includes the following steps: (1) Based on the analysis results of step S4, a parametric design method is adopted to establish a response relationship model between the air inlet area and local pressure, and to determine the adjustment scheme and optimization target of the air inlet in each region. (2) Based on the unevenness of air pressure distribution, formulate regional adjustment plans. For areas with low pressure, adjust gradually by reducing the area of ​​the air inlet by 5% or by reducing the number of air inlets to increase local pressure. For areas with high pressure, adjust gradually by increasing the area of ​​the air inlet by 5% or by increasing the number of air inlets to reduce local pressure. After each adjustment, record the changes in local pressure and ensure that the pressure changes are within a reasonable range to gradually achieve balanced pressure distribution. (3) Verify the adjusted scheme using numerical simulation methods. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions, and ensure that the simulation conditions are consistent with the previous analysis. Obtain the adjusted axial pressure distribution curve through simulation calculation, extract the pressure mean and fluctuation range of each region, and evaluate the adjustment effect. (4) Based on the simulation verification results, if the pressure distribution still does not reach the uniformity target, further optimize and adjust the scheme in combination with the local pressure deviation value. The optimization content includes adjusting the air inlet area or the number of air inlets. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range. (5) Determine the optimal scheme for the air intake area and the layout of the air intake position.

7. The method for uniformizing the axial air pressure distribution of a vacuum adsorption roller according to claim 6, characterized in that: Step S6 specifically includes the following steps: (1) Modify the air inlet hole on the actual vacuum adsorption roller according to the optimized scheme; (2) Install a digital pressure sensor array, and arrange no less than 10 pressure measuring points evenly along the roller axis. Use a data acquisition system to record the pressure value of each measuring point in real time, and monitor continuous operation conditions for no less than 8 hours. (3) Analyze and process the collected pressure data. First, filter and remove outliers from the raw data. Calculate the average value, standard deviation and fluctuation range of the pressure at each measuring point. Then, establish the axial pressure distribution curve and use the least squares method to fit the curve. Calculate the root mean square error of the fitted curve. Next, evaluate the uniformity of the axial pressure distribution and calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two ends of the axial direction and the middle area within ±8%, and control the pressure fluctuation coefficient below 0.

1. If the test results show that the pressure distribution in some areas does not meet the uniformity requirements, return to step S5 to make targeted adjustments to the air inlet parameters of the corresponding area according to the direction and magnitude of the pressure deviation. The adjustment range is determined according to 20%-30% of the pressure deviation. Repeat the optimization process until all indicators reach the set target and determine the final air inlet size and layout.

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