Uniform adjustment method for axial air pressure distribution of vacuum adsorption roller

Abstract

The invention discloses a homogenization adjustment method for axial air pressure distribution of a vacuum adsorption roller, which comprises the following steps of: firstly, accurately constructing a digital model of the vacuum adsorption roller by utilizing a reverse modeling technology and combining three-dimensional modeling software, then importing the model into CFD (Computational Fluid Dynamics) grid drawing software, performing fluid domain extraction and grid division, encrypting a key region, and finally, performing uniform adjustment on the axial air pressure distribution of the vacuum adsorption roller. Environmental parameters are configured in computational fluid dynamics software, then boundary conditions of an air inlet and an air outlet under actual working conditions are set, internal air pressure distribution is obtained through numerical simulation calculation, a simulation result is analyzed, an air pressure distribution area is recognized, and the area and layout of air inlet holes in all axial areas are adjusted according to the analysis result to balance the air inflow. And finally, verifying the effectiveness of the adjustment scheme in an actual production environment, and feeding back and optimizing the size and layout of the air inlet holes according to actual measurement data until a preset air pressure uniformity standard is reached. According to the method, precise control and optimization of axial air pressure distribution of the vacuum adsorption roller are realized.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum adsorption rollers, and in particular to a method for uniformly regulating the axial air pressure distribution of a vacuum adsorption roller. Background Art

[0002] The vacuum roller is one of the indispensable and important components in modern industrial production, especially in the papermaking, printing and packaging industries. It is mainly used as a dehydration element, working in the wire and press sections of the paper machine, using the negative pressure it generates to suck the moisture from the paper sheets or felt, thereby increasing the dryness of the paper and reducing the energy consumption required for drying. In addition, the vacuum roller is also used to maintain the stability and tension control of the roll material (such as paper, plastic film, etc.) during the processing process to ensure that the material does not deviate or deform during the processing process.

[0003] However, in practical applications, traditional vacuum rollers have some limitations, especially in terms of uniformity of web adsorption and edge control. When the web passes through the vacuum roller, due to uneven air pressure distribution, some areas of the web may have insufficient adsorption, which in turn causes curling, wrinkles and other problems, seriously affecting the quality and flatness of the product. These problems are particularly prominent in high-speed continuous production environments, which not only reduces production efficiency but also increases the scrap rate.

[0004] Therefore, the present application proposes a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller, aiming to provide a more stable and reliable web processing solution to meet the growing demand for high-quality product manufacturing. Summary of the invention

[0005] The purpose of the present invention is to provide a method for uniformly regulating the axial air pressure distribution of a vacuum adsorption roller, which ensures uniform adsorption of the coiled material, prevents curling, and improves product quality and production efficiency by intelligently controlling the air pressure in each area.

[0006] To achieve the above object, 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. Establishing a three-dimensional digital model of the vacuum adsorption roller:

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

[0009] S2. Import computational fluid dynamics software:

[0010] Import the three-dimensional model established in step S1 into the CFD mesh drawing software, extract the fluid domain and complete the mesh division, perform mesh encryption on the key area, and then import the calculation mesh into the computational fluid dynamics software and configure the environmental parameters;

[0011] S3. Set the working condition boundary for simulation calculation:

[0012] Given the boundary conditions of the air inlet and the air outlet of the vacuum adsorption roller when it is actually working, 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 of the vacuum adsorption roller:

[0014] Analyze the air pressure distribution data of each point on the surface of the vacuum adsorption roller from the simulation calculation results of step S3 to identify areas where the air pressure is too low or too high, especially areas where the air pressure difference between the two ends and the middle of the roller axis is large;

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

[0016] According to the analysis result of step S4, the area and layout of the air inlet holes in different axial regions are adjusted, so as to adjust the air intake volume in each region until a uniform air pressure distribution in the axial direction is obtained;

[0017] S6. Experimental verification and optimization adjustment:

[0018] In the actual production site, according to the adjustment plan of step S5, the area and layout of the air inlet holes in different axial areas of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial area before and after the adjustment, the feedback results are analyzed and used to further optimize the adjustment parameters until the uniformity of the air pressure distribution meets the predetermined requirements. Finally, the size and layout of the air inlet holes in each area are determined.

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

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

[0021] (2) importing the above point cloud data into reverse modeling software, and reconstructing the three-dimensional solid model of the overall outer surface of the roller using an automatic surface fitting algorithm;

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

[0023] (4) The reconstructed overall three-dimensional solid model is parametrically edited to ensure that the design size parameters of the roller body radius, length, air inlet and exhaust holes can be adjusted as needed.

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

[0025] (1) Importing the three-dimensional model established in step S1 into the CFD meshing software to 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 perform mesh encryption on the air inlet and exhaust holes. Set the mesh unit size to be within the range of 0.1 mm to 2 mm, and ensure that the orthogonality of the mesh quality parameters is not less than 0.3 and the distortion is not greater than 0.85;

[0027] (3) Import the divided grid into computational fluid dynamics software and set the physical property parameters of the fluid medium. Set the working medium to air and configure the air density to 1.225 kg / m 3 , set the dynamic viscosity to 1.789×10 -5 Pa·s, defining the working temperature as the standard atmospheric temperature;

[0028] (4) The standard k-ε turbulence model is used, 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 an iterative method to improve the convergence and computational stability of the numerical simulation;

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

[0030] (6) By setting 3-5 different grid densities for comparative calculations, monitoring the change patterns of pressure and velocity at key locations with the number of grids, and determining the final grid division scheme to ensure that the calculation results are not affected by the number of grids;

[0031] (7) A number of monitoring points are set in the axial direction of the vacuum adsorption roller according to the number of air inlet holes, wherein each monitoring point covers the same number of air inlet holes, thereby achieving real-time monitoring of the calculation process.

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

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

[0034] (1) Extract the pressure distribution data along the axial direction of the vacuum adsorption roller surface, establish the relationship curve between pressure and axial position, calculate the average pressure value and pressure fluctuation range of each area, and determine the unevenness 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 range that needs to be focused on adjustment;

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

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

[0038] (1) Based on the analysis results of step S4, a parameterized design method is used to establish a response relationship model between the air intake hole area and the local pressure, and an adjustment plan and optimization target for the air intake holes in each area are determined;

[0039] (2) According to the uneven distribution of air pressure, formulate regional adjustment plans. For areas with lower pressure, gradually adjust the area of ​​the air inlet holes by 5%, or reduce the number of air inlet holes to increase the local pressure. For areas with higher pressure, gradually adjust the area of ​​the air inlet holes by 5%, or increase the number of air inlet holes to reduce the local pressure. After each adjustment, the local pressure changes need to be recorded and ensured to be within a reasonable range, so as to gradually achieve balanced pressure distribution.

[0040] (3) Use numerical simulation methods to verify the adjusted scheme. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions, 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 area, and evaluate the adjustment effect;

[0041] (4) Based on the simulation verification results, if the pressure distribution still fails to reach the uniformity target, further optimize the adjustment plan in combination with the local pressure deviation value. The optimization content includes adjusting the intake hole area or the number of intake holes. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range.

[0042] (5) Determine the optimal solution for the air intake area and air intake hole location layout.

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

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

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

[0046] (3) Analyze and process the collected pressure data. First, filter the raw data and remove outliers. Calculate the average, standard deviation and fluctuation range of the pressure at each measuring point. Then establish the axial pressure distribution curve. Use the least square method to fit the curve. Calculate the root mean square error of the fitting curve. Then evaluate the uniformity of the axial pressure distribution. Calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two axial ends 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 adjust the air inlet parameters of the corresponding area according to the direction and size 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 the prior art, the advantages of the present invention are: this method realizes precise adjustment of the air pressure distribution of the vacuum adsorption roller through complete process design, combined with advanced modeling, numerical simulation and experimental optimization technology. 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 through three-dimensional modeling software to lay the foundation for subsequent analysis; Step S2 imports the three-dimensional model into the CFD mesh drawing software, extracts the fluid domain and performs high-quality mesh division, and performs mesh encryption processing on key areas such as air inlets and exhaust holes to ensure the accuracy and detailed expression of the simulation results. At the same time, the optimized mesh is imported into the computational fluid dynamics software, and the appropriate fluid medium 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 port according to the actual working conditions of the vacuum adsorption roller. , the internal air pressure distribution is obtained through numerical simulation; step S4 uses the simulation results to analyze the unevenness of the air pressure distribution on the roller surface, identify areas with too low or too high air pressure, especially for areas with large differences between the two axial ends and the middle, to provide a basis for subsequent adjustments; step S5 adjusts the area and layout of the air inlet holes in each axial area based on the analysis results, gradually optimizes the air intake volume in different areas, and ensures that the final air pressure distribution is uniform through repeated simulation and verification; step S6 verifies the optimization effect in an actual production environment, further adjusts the air inlet hole parameters according to the measured air pressure data, ensures that the axial pressure fluctuation is controlled within a reasonable range, and finally determines a stable and uniform air inlet hole size and layout plan.

[0048] This method introduces digital, visual and quantitative analysis methods, which can not only quickly locate the air pressure distribution problem, but also gradually achieve the uniformity of axial air pressure through iterative optimization. Finally, through field experimental verification and feedback, the optimal air inlet size and layout scheme can be finally determined, which can significantly improve the performance stability and work efficiency of the vacuum adsorption roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

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

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

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

[0053] Figure 4 This is a comparison chart of the flow data of the air inlet holes in different positions before and after adjustment. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] Embodiment 1: As shown in the figure, a method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller comprises the following steps:

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

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

[0058] S2. Import computational fluid dynamics software:

[0059] Import the three-dimensional model established in step S1 into the CFD mesh drawing software, extract the fluid domain and complete the mesh division, perform mesh encryption on the key area, and then import the calculation mesh into the computational fluid dynamics software and configure the environmental parameters;

[0060] S3. Set the working condition boundary for simulation calculation:

[0061] Given the boundary conditions of the air inlet and the air outlet of the vacuum adsorption roller when it is actually working, 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 of the vacuum adsorption roller:

[0063] Analyze the air pressure distribution data of each point on the surface of the vacuum adsorption roller from the simulation calculation results of step S3 to identify areas where the air pressure is too low or too high, especially areas where the air pressure difference between the two ends and the middle of the roller axis is large;

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

[0065] According to the analysis result of step S4, the area and layout of the air inlet holes in different axial regions are adjusted, so as to adjust the air intake volume in each region until a uniform air pressure distribution in the axial direction is obtained;

[0066] S6. Experimental verification and optimization adjustment:

[0067] In the actual production site, according to the adjustment plan of step S5, the area and layout of the air inlet holes in different axial areas of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial area before and after the adjustment, the feedback results are analyzed and used to further optimize the adjustment parameters until the uniformity of the air pressure distribution meets the predetermined requirements. Finally, the size and layout of the air inlet holes in each area are determined.

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

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

[0070] (2) importing the above point cloud data into reverse modeling software, and reconstructing the three-dimensional solid model of the overall outer surface of the roller using an automatic surface fitting algorithm;

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

[0072] (4) The reconstructed overall three-dimensional solid model is parametrically edited to ensure that the design size parameters of the roller body radius, length, air inlet and exhaust holes 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 using a 3D laser scanning system for all-round high-density point cloud data acquisition, this method can capture the geometric features of the vacuum adsorption roller, including its complex outer surface morphology and fine structural details, overcoming the limitations of traditional manual measurement methods; using advanced automatic surface fitting algorithms, point cloud data can be quickly converted into accurate 3D solid models, which not only retains the geometric accuracy of the original parts, but also significantly improves modeling efficiency; more importantly, this method can accurately reconstruct the internal cavity and airway structure by combining scanning data, design drawings and dimensional parameters, and accurately locate the spatial position and size of each air inlet and exhaust hole, laying a solid foundation for subsequent air pressure distribution simulation and optimization. In addition, the parametric editing of the reconstructed model allows key parameters such as roller radius, length, air inlet and exhaust holes to be dynamically adjusted according to actual process requirements, which not only greatly improves the accuracy and convenience of the design, but also creates great convenience for subsequent numerical simulation and performance optimization.

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

[0075] (1) Importing the three-dimensional model established in step S1 into the CFD meshing software to 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 perform mesh encryption on the air inlet and exhaust holes. Set the mesh unit size to be within the range of 0.1 mm to 2 mm, and ensure that the orthogonality of the mesh quality parameters is not less than 0.3 and the distortion is not greater than 0.85;

[0077] (3) Import the divided grid into computational fluid dynamics software and set the physical property parameters of the fluid medium. Set the working medium to air and configure the air density to 1.225 kg / m 3 , set the dynamic viscosity to 1.789×10 -5 Pa·s, defining the working temperature as the standard atmospheric temperature;

[0078] (4) The standard k-ε turbulence model is used, 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 an iterative method to improve the convergence and computational stability of the numerical simulation;

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

[0080] (6) By setting 3-5 different grid densities for comparative calculations, monitoring the change patterns of pressure and velocity at key locations with the number of grids, and determining the final grid division scheme to ensure that the calculation results are not affected by the number of grids;

[0081] (7) A number of monitoring points are set in the axial direction of the vacuum adsorption roller according to the number of air inlet holes, wherein each monitoring point covers the same number of air inlet holes, thereby achieving 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 to ensure that the numerical simulation can accurately reflect the actual physical space. In the meshing stage, a hexahedron or tetrahedron hybrid mesh method is used, and key parts such as the air inlet and exhaust holes are encrypted, the mesh unit size is set within the range of 0.1-2mm, and by strictly controlling the mesh quality parameters, such as orthogonality not less than 0.3 and distortion not more than 0.85, the accuracy and reliability of the numerical simulation can be significantly improved.

[0083] In terms of physical parameter configuration, the density, dynamic viscosity and operating temperature of the air are precisely set to provide accurate physical boundary conditions for subsequent numerical simulations. Selecting the standard k-ε turbulence model and setting the turbulence intensity to 5% is a typical method for simulating complex internal flows, which can better capture turbulent characteristics. The pressure-based solver and SIMPLE pressure-velocity coupling algorithm are used to achieve effective coupling of the pressure field and velocity field through iteration, which not only improves the convergence of the numerical simulation, but also enhances the stability of the calculation.

[0084] In terms of numerical discretization and solution, the second-order upwind format is selected to discretize the momentum equation and pressure term, and the PRESTO! pressure discretization format is adopted. These choices can significantly improve the numerical accuracy and calculation stability. By setting the convergence residual control value to 1×10-4, the high accuracy and reliability of the calculation results are ensured. To further verify the reliability of meshing, by comparing the calculation results of 3-5 different mesh densities, the variation of pressure and velocity at key positions is analyzed, and finally the optimal meshing scheme that can make the calculation results unaffected by the number of meshes is selected.

[0085] Each monitoring point covers the same number of exhaust holes. This monitoring method can not only realize accurate monitoring of the calculation process, but also directly link the air pressure and flow characteristics around each exhaust hole, providing a more accurate data basis for subsequent uniform adjustment of air pressure distribution.

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

[0087] This boundary condition setting achieves an accurate simulation of the actual working environment of the vacuum adsorption roller. Specifically, the air inlet pressure is set to standard atmospheric pressure (about 101.325 kPa) to simulate the air intake state under normal pressure; the exhaust port pressure is set within the 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 usually -40 kPa, then the exhaust port pressure can be accurately 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, so that the numerical simulation can be as close to the actual working conditions as possible, improving the reliability and accuracy of the simulation results.

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

[0089] (1) Extract the pressure distribution data along the axial direction of the vacuum adsorption roller surface, establish the relationship curve between pressure and axial position, calculate the average pressure value and pressure fluctuation range of each area, and determine the unevenness 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 range that needs to be focused on adjustment;

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

[0092] This step is the key step in regulating the uniform distribution of the air pressure of the vacuum roller. Through systematic data extraction and analysis, the precise quantification of the air pressure distribution characteristics can be achieved. First, by extracting the pressure distribution data along the axial direction of the vacuum roller surface, a pressure-axial position relationship curve is established, which can not only intuitively show the change trend of the air pressure along the axial direction, but also quantitatively evaluate the unevenness of the axial pressure distribution by calculating the average pressure value and pressure fluctuation range of each area.

[0093] Further quantitative analysis of the pressure difference between the two ends and the middle area of ​​the roller, by calculating the pressure gradient between adjacent areas, accurately identify the transition area where the pressure changes dramatically. This analysis can not only accurately locate the specific location of uneven pressure, but also provide an accurate reference for subsequent air inlet adjustment. In actual engineering, it may be found that the pressure gradient between the end area and the middle area is as high as 20-30kPa / 100mm. 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, establishing the corresponding relationship between the air inlet area and the local pressure, and combining it with the specific production process requirements, the target pressure value and the allowable pressure fluctuation range of each area can be accurately determined. For example, for a vacuum adsorption roller of a precision printing device, it may be required that the pressure fluctuation of each axial area be controlled within ±5%, and the target pressure value of the middle area be set to -40kPa, and the end area is allowed to fluctuate within the range of -35kPa to -45kPa.

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

[0096] (1) Based on the analysis results of step S4, a parameterized design method is used to establish a response relationship model between the air intake hole area and the local pressure, and an adjustment plan and optimization target for the air intake holes in each area are determined;

[0097] (2) According to the uneven distribution of air pressure, formulate regional adjustment plans. For areas with lower pressure, gradually adjust the area of ​​the air inlet holes by 5%, or reduce the number of air inlet holes to increase the local pressure. For areas with higher pressure, gradually adjust the area of ​​the air inlet holes by 5%, or increase the number of air inlet holes to reduce the local pressure. After each adjustment, the local pressure changes need to be recorded and ensured to be within a reasonable range, so as to gradually achieve balanced pressure distribution.

[0098] (3) Use numerical simulation methods to verify the adjusted scheme. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions, 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 area, and evaluate the adjustment effect;

[0099] (4) Based on the simulation verification results, if the pressure distribution still fails to reach the uniformity target, further optimize the adjustment plan in combination with the local pressure deviation value. The optimization content includes adjusting the intake hole area or the number of intake holes. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range.

[0100] (5) Determine the optimal solution for the air intake area and air intake hole location layout.

[0101] In the above steps, a response relationship model between the air inlet area and the local pressure is established through a parametric design method, laying the foundation for subsequent regulation. In view of the uneven distribution of air pressure, a regional optimization scheme based on incremental adjustment is proposed. For areas with lower pressure, the local pressure is increased by reducing the air inlet area by 5% or reducing the number of air inlets; for areas with higher pressure, the local pressure is reduced by increasing the air inlet area by 5% or increasing the number of air inlets. This gradual adjustment strategy ensures that each adjustment is within the controllable range and avoids drastic pressure fluctuations.

[0102] By performing numerical simulation verification in computational fluid dynamics software, the pressure distribution changes of each adjustment can be accurately tracked. For example, in a 1500mm long vacuum adsorption roller, the pressure in the end area may fluctuate within ±15% in the initial state. After multiple iterative adjustments, the pressure fluctuation can be controlled within ±5%. If the simulation results show that the pressure distribution still does not reach the uniformity target, the solution will continue to iterate and optimize according to the local pressure deviation value, adjust the area or number of the air inlet holes, and 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, and finally determine the air inlet area and layout plan to meet specific process requirements.

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

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

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

[0107] (3) Analyze and process the collected pressure data. First, filter the raw data and remove outliers. Calculate the average, standard deviation and fluctuation range of the pressure at each measuring point. Then establish the axial pressure distribution curve. Use the least square method to fit the curve. Calculate the root mean square error of the fitting curve. Then evaluate the uniformity of the axial pressure distribution. Calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two axial ends 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 adjust the air inlet parameters of the corresponding area according to the direction and size 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 optimization stage of the uniform adjustment of the air pressure distribution of the vacuum adsorption roller. Through systematic testing and data analysis under actual working conditions, the engineering verification of the numerical simulation results is realized. According to the previous optimization plan, the air inlet of the vacuum adsorption roller is modified to lay the foundation for accurate testing. The digital pressure sensor array is used to evenly arrange the pressure measurement points in the roller axis and conduct continuous operation monitoring for up to 8 hours. This design can not only capture the pressure distribution characteristics under steady-state operation, but also eliminate the accidental influence of short-term fluctuations.

[0109] The data processing link adopts rigorous scientific methods to ensure the reliability of data through filtering and outlier elimination. The least squares method is used to fit the axial pressure distribution curve, calculate the root mean square error, and evaluate the uniformity of pressure distribution from multiple dimensions. Specific evaluation indicators include the pressure gradient and coefficient of variation between adjacent measuring points. The pressure difference between the two ends and the middle area of ​​the axial direction is required to be controlled within ±8%, and the pressure fluctuation coefficient is controlled below 0.1. For example, in a 1500mm long vacuum adsorption roller, if the pressure fluctuation in the end area may be as high as ±15% in the initial state, it can be controlled within ±6% after optimization.

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

[0111] Example 2: Initial analysis of a vacuum roller in a paper mill

[0112] First, the vacuum adsorption roller is scanned in all directions using a 3D laser scanning system to obtain high-density point cloud data including the outer surface and end face of the roller. Then, the solidworks modeling software is used to reconstruct the 3D solid model of the roller, and the inner cavity and airway structure model is established in combination with the design drawings.

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

[0114] The inlet pressure is set to standard atmospheric pressure, and the exhaust pressure is set to a stable negative pressure value of -40Kpa. Numerical simulation is performed to obtain the initial axial air pressure distribution of the vacuum adsorption roller. The results show that the axial air pressure distribution is uneven, with areas of higher and lower pressure, especially at the two ends and the middle area of ​​the roller, showing obvious differences.

[0115] Based on the above analysis results, the parametric design method is used to adjust the area and layout of the air inlet holes. According to the pressure distribution data, the vacuum adsorption roller is divided into 19 monitoring positions, and each monitoring point covers 11 air inlet holes. In the initial case, the volume flow rate of each monitoring point and the average flow rate per hole are shown in Table 1.

[0116] Table 1 Volume flow rate and single hole average flow rate at each monitoring point under initial conditions

[0117]

[0118]

[0119] The pressure distribution under the original model calculation results is shown in the attached manual. Figure 2 shown.

[0120] The adjustment strategy includes reducing the number or area of ​​air inlet holes in the higher pressure area and increasing the number or area of ​​air inlet holes in the lower pressure area. After adjustment according to the optimization plan, the distribution of the number of blocked holes is shown in Table 2.

[0121] Table 2 Distribution of plugged hole quantity

[0122]

[0123]

[0124] After optimization, the numerical simulation calculation was performed again to obtain the adjusted air pressure distribution curve. The volume flow rate and single hole average flow rate of each monitoring point after optimization are shown in Table 3.

[0125] Table 3 Volume flow rate and single hole average flow rate of each monitoring point after optimization

[0126]

[0127]

[0128] The pressure distribution of the optimized model calculation results is shown in the attached figure. Figure 3 As shown, attached Figure 4 To compare the flow data of the air inlet holes at different positions before and after adjustment, Figure 3 It can be seen that there are significant differences in the flow rates of the air inlets at different positions. Initially, the air inlet flow rate is higher at both ends of the roller, while the flow rate in the middle area is lower. This distribution 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 single hole at each monitoring point is closer, 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 less than 10 digital pressure sensor arrays are installed, evenly arranged in the axial direction. The data acquisition system is used to record the pressure value of 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 and fluctuation range of the pressure at each measuring point. The variance of the pressure distribution after optimization was reduced from the initial 5.25518×10 -8 Reduced to 4.06042×10 -8 , indicating that the air pressure distribution is more uniform. The pressure gradient of adjacent measuring points is controlled within ±8%, and the pressure fluctuation coefficient is less than 0.1.

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

[0132] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for uniformly regulating the axial air pressure distribution of a vacuum adsorption roller, characterized in that: The following steps are included: S1. Establishing a three-dimensional digital model of the vacuum adsorption roller: The actual size and structure information of the vacuum adsorption roller are obtained by using reverse modeling technology, and a three-dimensional digital model that accurately corresponds to the real vacuum adsorption roller is established by using three-dimensional modeling software based on the actual size and structure information obtained; S2. Import computational fluid dynamics software: Import the three-dimensional model established in step S1 into the CFD mesh drawing software, extract the fluid domain and complete the mesh division, perform mesh encryption on the key area, and then import the calculation mesh into the computational fluid dynamics software and configure the environmental parameters; S3. Set the working condition boundary for simulation calculation: Given the boundary conditions of the air inlet and the air outlet of the vacuum adsorption roller when it is actually working, 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 of the vacuum adsorption roller: Analyze the air pressure distribution data of each point on the surface of the vacuum adsorption roller from the simulation calculation results of step S3 to identify areas where the air pressure is too low or too high, especially areas where the air pressure difference between the two ends and the middle of the roller axis is large; S5. Adjust the area and layout of the air inlet holes of the vacuum adsorption roller: According to the analysis result of step S4, the area and layout of the air inlet holes in different axial regions are adjusted, so as to adjust the air intake volume in each region until a uniform air pressure distribution in the axial direction is obtained; S6. Experimental verification and optimization adjustment: In the actual production site, according to the adjustment plan of step S5, the area and layout of the air inlet holes in different axial areas of the vacuum adsorption roller are optimized and adjusted. By measuring the actual air pressure distribution data of each axial area before and after the adjustment, the feedback results are analyzed and used to further optimize the adjustment parameters until the uniformity of the air pressure distribution meets the predetermined requirements. Finally, the size and layout of the air inlet holes in each area are determined.

2. The method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: The step S1 specifically includes the following steps: (1) Using a three-dimensional laser scanning system to perform an all-round scan of the vacuum adsorption roller in a stationary state, obtaining high-density point cloud data including the outer surface and end surface of the roller; (2) importing the above point cloud data into reverse modeling software, and reconstructing the three-dimensional solid model of the overall outer surface of the roller using an automatic surface fitting algorithm; (3) Based on the scanned point cloud data, combined with the design drawings and dimensional parameters of the vacuum adsorption roller, the internal cavity and airway structure model is established, and the spatial position and size of each air inlet and exhaust hole on the three-dimensional model are accurately located; (4) The reconstructed overall three-dimensional solid model is parametrically edited to ensure that the design size parameters of the roller body radius, length, air inlet and exhaust holes can be adjusted as needed.

3. The method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: The step S2 specifically includes the following steps: (1) Importing the three-dimensional model established in step S1 into the CFD meshing software to 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 perform mesh encryption on the air inlet and exhaust holes. Set the mesh unit size to be within the range of 0.1 mm to 2 mm, and ensure that the orthogonality of the mesh quality parameters is not less than 0.3 and the distortion is not greater than 0.85; (3) Import the divided grid into computational fluid dynamics software and set the physical property parameters of the fluid medium. Set the working medium to air and configure the air density to 1.225 kg / m 3 , set the dynamic viscosity to 1.789×10 -5 Pa·s, defining the working temperature as the standard atmospheric temperature; (4) The standard k-ε turbulence model is used, 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 an iterative method to improve the convergence and computational stability of the numerical simulation; (5) Set the momentum equation and pressure term to the second-order upwind format, the pressure term to the PRESTO! format, the turbulent kinetic energy and dissipation rate to the second-order upwind format, and configure the convergence residual control value to be 1×10 -4 ; (6) By setting 3-5 different grid densities for comparative calculations, monitoring the change patterns of pressure and velocity at key locations with the number of grids, and determining the final grid division scheme to ensure that the calculation results are not affected by the number of grids; (7) A number of monitoring points are set in the axial direction of the vacuum adsorption roller according to the number of air inlet holes, wherein each monitoring point covers the same number of air inlet holes, thereby achieving real-time monitoring of the calculation process.

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

5. The method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: The step S4 specifically comprises the following steps: (1) Extract the pressure distribution data along the axial direction of the vacuum adsorption roller surface, establish the relationship curve between pressure and axial position, calculate the average pressure value and pressure fluctuation range of each area, and determine the unevenness 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 range that needs to be focused on adjustment; (3) Analyze the flow distribution at each air inlet, establish the corresponding relationship between the air inlet area and the local pressure, and determine the target pressure value and allowable pressure fluctuation range of each area in combination with the production process requirements.

6. The method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: The step S5 specifically comprises the following steps: (1) Based on the analysis results of step S4, a parameterized design method is used to establish a response relationship model between the air intake hole area and the local pressure, and an adjustment plan and optimization target for the air intake holes in each area are determined; (2) According to the uneven distribution of air pressure, formulate regional adjustment plans. For areas with lower pressure, gradually adjust the area of ​​the air inlet holes by 5%, or reduce the number of air inlet holes to increase the local pressure. For areas with higher pressure, gradually adjust the area of ​​the air inlet holes by 5%, or increase the number of air inlet holes to reduce the local pressure. After each adjustment, the local pressure changes need to be recorded and ensured to be within a reasonable range, so as to gradually achieve balanced pressure distribution. (3) Use numerical simulation methods to verify the adjusted scheme. Import the adjusted model into the computational fluid dynamics software, reset the fluid domain and boundary conditions, 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 area, and evaluate the adjustment effect; (4) Based on the simulation verification results, if the pressure distribution still fails to reach the uniformity target, further optimize the adjustment plan in combination with the local pressure deviation value. The optimization content includes adjusting the intake hole area or the number of intake holes. Repeat the optimization and verification process until the axial pressure fluctuation is controlled within the preset range. (5) Determine the optimal solution for the air intake area and air intake hole location layout.

7. The method for uniformly adjusting the axial air pressure distribution of a vacuum adsorption roller according to claim 1, characterized in that: The step S6 specifically comprises the following steps: (1) Modify the air inlet holes on the actual vacuum adsorption roller according to the optimization scheme; (2) Install a digital pressure sensor array, evenly arrange no less than 10 pressure measuring points in the roller axis, use a data acquisition system to record the pressure value of each measuring point in real time, and monitor the continuous operation condition for no less than 8 hours; (3) Analyze and process the collected pressure data. First, filter the raw data and remove outliers. Calculate the average, standard deviation and fluctuation range of the pressure at each measuring point. Then establish the axial pressure distribution curve. Use the least square method to fit the curve. Calculate the root mean square error of the fitting curve. Then evaluate the uniformity of the axial pressure distribution. Calculate the pressure gradient and coefficient of variation between adjacent measuring points. Control the pressure difference between the two axial ends 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 adjust the air inlet parameters of the corresponding area according to the direction and size 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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