Aluminum plate flattening residual stress elimination method based on dynamic roll gap and tension cooperation

Abstract

This invention discloses a method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination, relating to the field of metal sheet processing technology. It involves real-time acquisition of two-dimensional temperature field data across the entire aluminum plate using an infrared array temperature measurement unit, constructing a multi-physics field correlation model of deformation heat generation, temperature field evolution, dynamic change in material yield strength, and residual stress release. This model clarifies the dynamic influence of temperature on material yield strength. Using temperature field distribution as boundary conditions and a bi-objective optimization function as the core criterion, a coordinated matching matrix is ​​constructed based on roll gap reduction, tension value, and temperature field distribution. Differentiated coordinated control of roll gap and tension is simultaneously executed for different temperature regions, ultimately achieving multi-field coordinated closed-loop control of temperature field, roll gap, and tension.

Description

Technical Field

[0001] This invention relates to the field of metal sheet processing technology, specifically to a method for eliminating residual stress in aluminum sheet leveling based on the synergy of dynamic roll gap and tension. Background Technology

[0002] Aluminum alloy sheets, with their superior properties such as lightweight, high strength, corrosion resistance, and ease of forming, occupy an important position in high-end manufacturing fields such as aerospace, automobile manufacturing, rail transportation, and 3C electronics. In the cold rolling production process of aluminum sheets, factors such as uneven rolling deformation and fluctuations in coiling tension inevitably induce residual stress inside the aluminum sheet. If these residual stresses are not fully eliminated, the aluminum sheet is prone to a series of problems such as warping, deformation, out-of-tolerance dimensional accuracy, and even cracking in subsequent processing stages such as shearing, stamping, and bending, which seriously restricts the improvement of product yield and performance.

[0003] However, existing leveling processes and related technologies have many shortcomings, making it difficult to meet the requirements of high-end aluminum plates for uniform residual stress. Most existing leveling process parameter designs are based on the assumption of room temperature uniformity, neglecting the deformation heat effect generated by repeated elasto-plastic deformation of the aluminum plate during leveling. In actual production, when the aluminum plate passes through the leveling rollers at high speed, continuous reverse bending deformation generates a large amount of deformation heat, causing the aluminum plate temperature to rise rapidly. Furthermore, due to differences in the degree of deformation in the transverse and longitudinal directions, a non-uniform temperature field is formed. Since the yield strength and elasto-plastic deformation threshold of aluminum alloys are highly sensitive to temperature, this non-uniform temperature distribution directly leads to uneven residual stress in the aluminum plate. Differences in yield characteristics and stress release patterns within the same region ultimately lead to large fluctuations in residual stress elimination and poor uniformity in plate shape. Existing leveling technologies mostly employ a single roll gap reduction control or a single tension control mode, failing to achieve coordinated matching between roll gap and tension, and lacking quantitative coordinated proportioning rules. In response to the dynamic changes in material properties caused by temperature field, single parameter control cannot simultaneously take into account sufficient plastic deformation and work hardening control, easily leading to problems such as work hardening and secondary stress concentration caused by local over-correction, or insufficient residual stress elimination caused by local under-correction, making it difficult to meet the requirements of high-end aluminum plates for uniform residual stress. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination. This method uses an infrared array temperature measurement unit to collect real-time two-dimensional temperature field data across the entire aluminum plate, constructing a multi-physics field correlation model of deformation heat generation, temperature field evolution, dynamic change in material yield strength, and residual stress release. This model clarifies the dynamic influence of temperature on material yield strength. Using temperature field distribution as boundary conditions and a dual-objective optimization function as the criterion, a coordinated matching matrix is ​​constructed based on roll gap reduction, tension value, and temperature field distribution. Differentiated coordinated control of roll gap and tension is simultaneously executed for different temperature regions, ultimately achieving multi-field coordinated closed-loop control of temperature field, roll gap, and tension.

[0005] To solve the above-mentioned technical problems, this invention provides the following technical solution: a method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension, which includes the following specific steps: S1: Based on the room temperature material mechanical properties of the aluminum plate to be leveled, preset the initial roll gap reduction and initial tension parameters, deploy an infrared array temperature measurement unit in the leveling roll interval, and complete the online debugging of the production line and the temperature measurement system. S2: After the aluminum plate enters the production line, the initial tension is established and continuous leveling is performed. The infrared array temperature measurement unit collects the spatiotemporal distribution data of the two-dimensional temperature field of the aluminum plate in the transverse and longitudinal directions in real time, and collects the production line operating data and transmits it to the industrial controller. S3: Construct a multiphysics field correlation model of deformation heat generation, temperature field evolution, dynamic change of material yield strength, and residual stress release to quantify the dynamic changes of aluminum plate yield strength and elastoplastic deformation threshold in different temperature ranges. S4: Using real-time temperature field distribution as boundary conditions and the control objectives of uniform elimination of residual stress and optimal flatness of the plate, a collaborative matching matrix of dynamic roll gap reduction, tension value and temperature field distribution is constructed. S5: Based on the instructions output by the collaborative matching matrix, the corresponding roll gap reduction and tension value are reduced synchronously for the high temperature and low yield region, and the corresponding roll gap reduction and tension gradient are increased synchronously for the low temperature and high yield stress concentration region, so as to achieve multi-field collaborative dynamic control. S6: Collect temperature field, plate shape and residual stress data of the aluminum plate after regulation, and feed back to optimize the multiphysics correlation model and collaborative matching matrix to form a closed-loop regulation throughout the entire process until the leveling operation is completed.

[0006] Furthermore, in S2, the production line operating data includes the aluminum plate traveling speed, the real-time roll gap reduction of each leveling roller, the real-time tension value of the inlet tension roller and the outlet tension roller, and the rotational speed of the leveling roller.

[0007] Furthermore, in S3, the construction of the multiphysics correlation model specifically includes the following steps: Based on the theory of elastic-plastic deformation and the first law of thermodynamics, and combined with the parameters of leveling roll arrangement, roll gap reduction, and aluminum plate travel speed, the amount of deformation heat generated by the aluminum plate during repeated bending deformation in each leveling roll track is calculated; combined with the boundary conditions of heat conduction and heat convection between the aluminum plate and the environment, a temperature field spatiotemporal evolution sub-model is constructed to simulate the dynamic distribution law of the temperature field across the entire aluminum plate. Based on the material properties of the aluminum plate to be leveled, stress-strain curves of the aluminum plate at different temperatures are obtained through high-temperature tensile tests. A quantitative constitutive relationship between the yield strength of the aluminum plate and temperature is established. The constitutive relationship is embedded into the spatiotemporal evolution sub-model of the temperature field to quantify the dynamic decay of the yield strength of the aluminum plate at different temperatures. By combining the dynamic constitutive relation of materials with the theory of residual stress release during aluminum plate leveling, a mapping relationship between different temperatures, different degrees of plastic deformation and residual stress release efficiency is established, and a multi-physics field correlation model is constructed to complete the deformation heat generation, temperature field evolution, dynamic change of material yield strength and residual stress release.

[0008] Furthermore, the expression for the yield strength-temperature constitutive relation of the aluminum plate is as follows: ,in, For temperature Yield strength of the lower aluminum plate room temperature Yield strength of the lower aluminum plate The temperature decay coefficient of yield strength. This refers to the real-time temperature of the aluminum plate. The value is room temperature, taken as 20℃.

[0009] Furthermore, in S4, the construction of the collaborative matching matrix specifically includes the following steps: Based on the lateral spatial resolution of the infrared array temperature measurement unit, the partition control capability of the leveling machine roll gap servo mechanism, the aluminum plate travel speed and temperature sampling frequency, the entire surface of the aluminum plate to be leveled is divided into several independent gridded control units. Based on the constructed multiphysics field correlation model, a reference temperature threshold and a safety boundary for the control parameters are set. With the goal of uniformly eliminating residual stress in aluminum plates and the auxiliary goal of optimizing the flatness accuracy of the plate, a multi-objective control function with constraints is constructed. Based on the multiphysics correlation model, the mapping relationship between the temperature change of aluminum plate and the correction coefficient of roll gap reduction and tension value is calibrated within different temperature deviation ranges. At the same time, the synergistic matching coefficient of roll gap and tension is calibrated. A two-dimensional collaborative matching matrix is ​​constructed using gridded control units as the basic unit, with each matrix element corresponding to a gridded control unit; the update frequency of the matrix is ​​kept consistent with the sampling frequency of the infrared array temperature measurement unit, so as to realize real-time synchronization of input parameters and output commands. The typical temperature field distribution data and extreme working condition data collected offline are input into the constructed collaborative matching matrix. The control effect is simulated through a multiphysics correlation model to verify whether the output control parameters are within the safety boundary and whether they meet the requirements of the multi-objective control function. If the verification fails, the collaborative matching coefficient is recalibrated. If the verification passes, the upper and lower limit thresholds of the control parameters are locked to complete the final construction of the collaborative matching matrix.

[0010] Furthermore, the gridded control unit is divided into N equal-width control zones along the width of the aluminum plate in the horizontal direction, where N is positively correlated with the number of infrared temperature probes, and each control zone corresponds to at least one set of data collected by the infrared temperature probes; in the vertical direction, it is divided into several equal-length control segments along the traveling direction of the aluminum plate, and the length of each control segment is determined by the ratio of the real-time traveling speed of the aluminum plate to the sampling frequency of the infrared array temperature measurement unit.

[0011] Furthermore, the expression for the multi-objective control function is: ,in, This represents the residual stress control weighting coefficient. Weights are used to control the plate shape accuracy. The overall control target value; The standard deviation of residual stress for all gridded control units across the entire aluminum plate surface. The full-width panel shape error value of the aluminum plate is defined by the following constraints: the degree of plastic deformation of each unit of the aluminum plate does not exceed the critical strain value of material work hardening, the tension value does not exceed the yield limit of the aluminum plate at the corresponding temperature, and the residual stress control weight coefficient is set to be no less than 0.6. The sum of the residual stress control weight coefficient and the panel shape accuracy control weight coefficient is 1.

[0012] Furthermore, the reference temperature threshold includes a static reference threshold or a dynamic reference threshold, wherein the static reference threshold is the critical temperature value corresponding to the yield strength of the aluminum plate to be leveled at room temperature, and the dynamic reference threshold is the average temperature value collected in real time across the entire aluminum plate; the safety boundary of the control parameters includes the roll gap reduction adjustment boundary and the tension value adjustment boundary, wherein the fluctuation range of the roll gap reduction correction value does not exceed ±30% of the initial roll gap reduction value at the corresponding position, and the fluctuation range of the tension value correction value does not exceed ±25% of the preset initial tension value of the leveling production line, so as to avoid plate shape defects, aluminum plate tearing or equipment damage caused by exceeding the control parameters.

[0013] Furthermore, the rows of the two-dimensional collaborative matching matrix correspond to the longitudinal control segments, and the columns of the matrix correspond to the lateral control partitions. The input parameters of the matrix elements include the real-time average temperature of the unit, the temperature deviation value, and the real-time yield strength and residual stress prediction values ​​output based on the multi-physics correlation model. The output parameters include the roll gap reduction correction value and tension value correction value corresponding to the unit.

[0014] Furthermore, the temperature deviation is the difference between the real-time temperature of the gridded unit and the reference temperature threshold, divided into positive deviation and negative deviation intervals. For the positive deviation interval, the roll gap reduction coefficient and tension value reduction coefficient corresponding to each 1°C increase in temperature are calibrated. The reduction in roll gap reduction is positively correlated with the positive temperature deviation value of the unit, and the reduction in tension value is positively correlated with the average positive temperature deviation value of the corresponding longitudinal segment. Simultaneously, the ratio of the roll gap reduction coefficient to the tension value reduction coefficient is calibrated as the coordination ratio coefficient for the positive deviation interval. For the negative deviation interval... The roll gap reduction adjustment coefficient and the tension gradient adjustment coefficient were calibrated for each 1°C decrease in temperature. The increase in roll gap reduction was positively correlated with the absolute value of the negative temperature deviation of the gridded unit and the stress concentration correction coefficient. The increase in tension gradient was positively correlated with the absolute value of the average negative temperature deviation of the corresponding longitudinal segment and the average stress concentration correction coefficient. The ratio of the roll gap reduction adjustment coefficient to the tension gradient adjustment coefficient was calibrated as the synergistic ratio coefficient of the negative deviation interval. The stress concentration correction coefficient was not less than 1 and was positively correlated with the initial residual stress amplitude of the unit.

[0015] Compared with existing technologies, this method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension has the following advantages: This invention couples the deformation heat-temperature field spatiotemporal distribution characteristics during the leveling process, and utilizes an infrared array temperature measurement unit to achieve real-time, high-precision acquisition of the full-width two-dimensional temperature field of the aluminum plate, capturing the non-uniform temperature distribution characteristics and providing a basis for dynamic control. It constructs a fully quantified multi-physics field correlation model, using the yield strength-temperature constitutive relationship formula to quantify the dynamic influence of temperature on the material's mechanical properties, and establishes a mathematical mapping relationship. Through a quantified roll gap-tension-temperature field collaborative matching matrix construction method, and using a multi-objective optimization function as the criterion, it achieves refined and differentiated control of the entire aluminum plate, significantly improving control accuracy and adaptability. Based on the collaborative matching matrix and quantified collaborative proportioning rules, it achieves synchronous collaborative control of roll gap reduction and tension, allowing for on-demand control of different temperature regions, improving the uniformity of residual stress elimination and plate shape consistency.

[0016] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a flowchart illustrating the method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension. Figure 2 A flowchart illustrating the construction of a multiphysics correlation model for a method to eliminate residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension. Figure 3 This is a flowchart of the collaborative matching matrix construction for a method to eliminate residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Reference Figure 1 This invention proposes a method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination. It adopts a control mechanism that integrates real-time acquisition of temperature field from a full-width infrared array, multi-physics field correlation modeling of deformation heat, temperature field, material mechanical properties, and residual stress, and gridded roll gap and tension coordinated closed-loop control. This method can overcome the shortcomings of traditional leveling processes that ignore the dynamic changes in material yield strength caused by deformation heat and cannot adapt to the non-uniform distribution of mechanical properties across the entire aluminum plate. It achieves dual-objective coordinated control of uniformly eliminating residual stress in aluminum plates and optimizing plate shape accuracy, and provides high-precision and robust online dynamic control for the entire aluminum plate leveling process.

[0021] The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension in this embodiment specifically includes: Determine the room temperature mechanical properties of the aluminum plate to be leveled, preset the initial roll gap reduction and initial tension parameters, deploy the infrared array temperature measurement unit, and complete the online debugging of the production line and the temperature measurement system. After the aluminum plate enters the line, the initial tension is established, continuous leveling operation is performed, and real-time data on the spatiotemporal distribution of the two-dimensional temperature field of the entire aluminum plate and the operating conditions of the production line are collected and transmitted synchronously to the industrial controller. A multiphysics model is constructed to quantify the dynamic changes in the mechanical properties of aluminum plates related to temperature, including deformation heat generation, temperature field evolution, dynamic changes in material yield strength, and residual stress release. Using real-time temperature field distribution as boundary condition and uniform elimination of residual stress and optimal plate shape accuracy as control objectives, a collaborative matching matrix of dynamic roll gap reduction, tension value and temperature field distribution is constructed. Based on the output instructions of the collaborative matching matrix, differentiated collaborative control of roll gap and tension is performed for different temperature zones to achieve multi-field collaborative dynamic adaptation; After collecting and adjusting the temperature field, shape, and residual stress data of the aluminum plate, the multiphysics correlation model and collaborative matching matrix are optimized to form a closed-loop control throughout the entire process until the leveling operation is completed.

[0022] Specifically, a standard room temperature tensile test is conducted on the aluminum plate to be leveled to obtain its material mechanical properties parameters such as yield strength, tensile strength, elongation after fracture, and elastic modulus at room temperature. Based on the leveling machine's roller system layout parameters (number of leveling rollers, roller diameter, roller spacing) and aluminum plate specifications (thickness, width), the initial roller gap reduction for the leveling operation is preset, ensuring that the reduction per pass does not exceed the maximum allowable elastic-plastic deformation threshold of the aluminum plate at room temperature. Simultaneously, the initial tension values ​​of the inlet and outlet tension rollers are preset, ensuring that the initial tension values ​​do not exceed 70% of the aluminum plate's room temperature yield strength to avoid excessive tension leading to tensile deformation of the aluminum plate. An infrared array temperature measurement unit is deployed in the leveling roller interval between the leveling machine's inlet and outlet. The temperature measurement unit horizontally covers the full width of the aluminum plate and vertically covers the core deformation area of ​​the leveling operation. The horizontal spatial resolution of the temperature probe matches the leveling machine's roller gap zone control capability. Communication connections are established between the infrared array temperature measurement unit and the industrial controller, the leveling machine's roller gap servo system, and the tension roller servo system. Online debugging is performed to ensure that the time synchronization error between data acquisition and command issuance by each system does not exceed the set threshold.

[0023] Specifically, after the aluminum sheet to be leveled is uncoiled by the uncoiler, it enters the leveling production line. A preset initial tension is established through the inlet tension roller, and the sheet is smoothly fed into the leveling machine unit to perform continuous leveling operations. After the aluminum sheet enters the deformation zone of the leveling roller, the deployed infrared array temperature measurement unit collects real-time spatiotemporal distribution data of the two-dimensional temperature field of the entire horizontal and vertical area of ​​the aluminum sheet, and obtains the real-time temperature value of each sampling point and the temperature distribution cloud map of the entire area. Simultaneously, the sensors of the production line collect real-time operating data of the leveling operation. All collected data are accompanied by a unified timestamp and are transmitted to the industrial controller in real time, providing a basic data source for subsequent multi-physics field modeling and collaborative control. The production line operating data includes the aluminum sheet traveling speed, the real-time roll gap reduction of each leveling roller, the real-time tension value of the inlet tension roller and the outlet tension roller, and the real-time rotation speed of the leveling roller.

[0024] For example, during the leveling operation, the aluminum plate travel speed is set to 60m / min. The infrared array temperature measurement unit collects one frame of full-width temperature data of the aluminum plate every 20ms. The data is collected in 12 horizontal zones and a sampling point is set every 20mm along the travel direction of the aluminum plate in the longitudinal direction, forming continuous two-dimensional temperature field spatiotemporal distribution data. Simultaneously, the real-time roll gap reduction of 19 leveling rollers, the real-time tension value of the inlet and outlet tension rollers, and the real-time speed of the leveling roller drive motor are collected. All data are configured with a unified system timestamp, and the data transmission delay is ≤5ms to ensure the spatiotemporal matching of temperature field data and working condition data.

[0025] Specifically, such as Figure 2 As shown, based on the theory of elastoplastic deformation and the first law of thermodynamics, and combined with the process parameters of leveling roll arrangement, roll gap reduction, and aluminum plate travel speed, the plastic deformation work and deformation heat generation of the aluminum plate during repeated bending deformation in each leveling roll path are calculated. A temperature field spatiotemporal evolution sub-model is constructed by combining the boundary conditions of heat conduction and convection between the aluminum plate and the air environment and the leveling rolls to simulate the dynamic distribution law of the temperature field across the entire aluminum plate. Based on the material properties of the aluminum plate to be leveled, stress-strain curves of the aluminum plate under different temperature gradients are obtained through high-temperature tensile tests. A quantitative constitutive relationship between the yield strength of the aluminum plate and temperature is established. This constitutive relationship is embedded into the temperature field spatiotemporal evolution sub-model to quantify the dynamic attenuation of the yield strength of the aluminum plate and the dynamic change of the elastoplastic deformation threshold in different temperature ranges. Combining the material dynamic constitutive relationship and the theory of residual stress release during aluminum plate leveling, a mapping relationship between different temperatures, different degrees of plastic deformation, and residual stress release efficiency is established. Finally, a multi-physics field correlation model is constructed, encompassing deformation heat generation, temperature field evolution, dynamic change of material yield strength, and residual stress release.

[0026] The calculation process of the yield strength-temperature constitutive relation of aluminum plate can be expressed as follows: ,in, For temperature Yield strength of the lower aluminum plate room temperature Yield strength of the lower aluminum plate The temperature decay coefficient of yield strength. This refers to the real-time temperature of the aluminum plate. The value is room temperature, taken as 20℃.

[0027] For example, for 5052-O temper aluminum alloy plates, the yield strength temperature decay coefficient was measured by a gradient high-temperature tensile test from 20℃ to 150℃. =0.35; room temperature At 20℃, =110MPa, when the real-time temperature of a certain gridded control unit of the aluminum plate is... At 60℃, the yield strength of the aluminum plate at that temperature can be calculated by substituting into the formula. =96MPa, the yield strength at which the aluminum plate decreases by 14MPa is obtained by quantification. The elastic-plastic deformation threshold decreases simultaneously. By embedding the constitutive relation into the spatiotemporal evolution sub-model of the temperature field, the dynamic mechanical response of the material at different temperature points across the entire aluminum plate can be simulated. Combined with the theory of leveling plastic deformation, it is determined that the amount of plastic deformation required for the aluminum plate to achieve the same residual stress release efficiency at 60℃ is 12.7% lower than that at room temperature, providing a quantitative basis for subsequent coordinated control.

[0028] Specifically, such as Figure 3 As shown, based on the lateral spatial resolution of the infrared array temperature measurement unit, the zoned control capability of the leveling machine's roll gap servo mechanism, the aluminum plate's travel speed, and the temperature sampling frequency, the entire surface of the aluminum plate to be leveled is divided into several independent gridded control units. Based on the constructed multi-physics field correlation model, a reference temperature threshold and a safety boundary for the control parameters are set. With the uniform elimination of residual stress in the aluminum plate as the core objective and the optimal leveling plate shape accuracy as the auxiliary objective, a multi-objective control function with constraints is constructed. Based on the multi-physics field correlation model, the mapping relationship between the aluminum plate temperature change and the roll gap reduction correction coefficient and tension value correction coefficient within different temperature deviation ranges is calibrated. The coordinated ratio coefficient of roll gap and tension is determined. A two-dimensional coordinated matching matrix is ​​constructed using gridded control units as the basic unit. The update frequency of the matrix is ​​consistent with the sampling frequency of the infrared array temperature measurement unit to achieve real-time synchronization of input parameters and output commands. Typical temperature field distribution data and extreme working condition data collected offline are input into the constructed coordinated matching matrix. The control effect is simulated through a multi-physics correlation model to verify whether the output control parameters are within the safety boundary and whether they meet the requirements of the multi-objective control function. If the verification fails, the coordinated ratio coefficient is recalibrated. If the verification passes, the upper and lower limit thresholds of the control parameters are locked to complete the final construction of the coordinated matching matrix.

[0029] The gridded control unit is divided into N equal-width control zones along the width of the aluminum plate, with N being positively correlated with the number of infrared temperature probes. Each control zone corresponds to at least one set of data collected by the infrared temperature probes. The unit is also divided into several equal-length control segments along the direction of travel of the aluminum plate. The length of each control segment is determined by the ratio of the real-time travel speed of the aluminum plate to the sampling frequency of the infrared array temperature measurement unit.

[0030] The reference temperature threshold includes a static reference threshold or a dynamic reference threshold. The static reference threshold is the critical temperature value corresponding to the yield strength of the aluminum plate to be leveled at room temperature, while the dynamic reference threshold is the average temperature value collected in real time across the entire aluminum plate. The safety boundaries of the control parameters include the roll gap reduction adjustment boundary and the tension value adjustment boundary. The fluctuation range of the roll gap reduction correction value does not exceed ±30% of the initial roll gap reduction value at the corresponding position, and the fluctuation range of the tension value correction value does not exceed ±25% of the preset initial tension value of the leveling production line, so as to avoid plate shape defects, aluminum plate tearing, or equipment damage caused by exceeding the control parameters.

[0031] The rows of the two-dimensional collaborative matching matrix correspond to the longitudinal control segments, and the columns of the matrix correspond to the lateral control zones. The input parameters of the matrix elements include the real-time average temperature of the unit, the temperature deviation value, and the real-time yield strength and residual stress prediction values ​​output based on the multi-physics correlation model. The output parameters include the roll gap reduction correction value and tension value correction value corresponding to the unit.

[0032] Temperature deviation is the difference between the real-time temperature of the gridded unit and the reference temperature threshold, divided into positive and negative deviation intervals. For the positive deviation interval, the roll gap reduction coefficient and tension reduction coefficient corresponding to each 1°C increase in temperature are calibrated. The reduction in roll gap reduction is positively correlated with the positive temperature deviation of the unit, and the reduction in tension is positively correlated with the average positive temperature deviation of the corresponding longitudinal segment. Simultaneously, the ratio of the roll gap reduction coefficient to the tension reduction coefficient is calibrated as the coordination ratio coefficient for the positive deviation interval. For the negative deviation interval, the following is calibrated: The adjustment coefficients for roll gap reduction and tension gradient are calculated for each 1°C decrease in temperature. The increase in roll gap reduction is positively correlated with the absolute value of the negative temperature deviation of the gridded unit and the stress concentration correction coefficient. The increase in tension gradient is positively correlated with the absolute value of the average negative temperature deviation and the average stress concentration correction coefficient of the corresponding longitudinal segment. The ratio of the adjustment coefficient for roll gap reduction to the adjustment coefficient for tension gradient is calibrated as the synergistic ratio coefficient for the negative deviation range. The stress concentration correction coefficient is not less than 1 and is positively correlated with the initial residual stress amplitude of the unit.

[0033] The expression for the multi-objective control function is: ,in, This represents the residual stress control weighting coefficient. Weights are used to control the plate shape accuracy. The overall control target value; The standard deviation of residual stress for all gridded control units across the entire aluminum plate surface. The full-width panel shape error value of the aluminum plate is defined by the following constraints: the degree of plastic deformation of each unit of the aluminum plate does not exceed the critical strain value of material work hardening, the tension value does not exceed the yield limit of the aluminum plate at the corresponding temperature, and the residual stress control weight coefficient is set to be no less than 0.6. The sum of the residual stress control weight coefficient and the panel shape accuracy control weight coefficient is 1.

[0034] For example, for a 1200mm wide 5052 aluminum alloy plate, the width is divided into 12 equal-width control zones (N=12) in the transverse direction. Each zone corresponds to the data collected by one set of infrared temperature probes. The aluminum plate travels at a speed of 1m / s, the infrared array temperature measurement unit has a sampling frequency of 50Hz, and the length of each control segment in the longitudinal direction is 20mm, ultimately forming 12 columns × several rows of independent gridded control units. The static reference temperature threshold is set to 40℃, the roll gap reduction adjustment boundary is ±30% of the initial reduction, the initial roll gap reduction is 0.15mm, and the corresponding adjustment range is 0.105mm-0.195mm; the tension value adjustment boundary is ±25% of the initial average tension value, the initial average tension value is 20MPa, and the corresponding adjustment range is 15MPa-25MPa. A residual stress control weighting coefficient is set. =0.7, weighting coefficient for plate shape accuracy control =0.3, construct a multi-objective control function, and calibrate parameters based on the multi-physics correlation model: In the positive deviation range (temperature > 40℃), for every 1℃ increase in temperature, the roll gap reduction coefficient is reduced by 0.25%, the tension value reduction coefficient is reduced by 0.2%, and the positive deviation range coordination ratio coefficient is 1.25; In the negative deviation range (temperature < 40℃), for every 1℃ decrease in temperature, the roll gap reduction coefficient is increased by 0.3%, the tension gradient increase coefficient is increased by 0.24%, and the negative deviation range coordination ratio coefficient is 1.25; The stress concentration correction coefficient ranges from 1.0 to 1.5 and is positively correlated with the initial residual stress amplitude of the element.

[0035] A two-dimensional collaborative matching matrix was constructed, with rows corresponding to vertical control segments and columns corresponding to horizontal control zones. The matrix update frequency was set to 50Hz, consistent with the sampling frequency of the infrared array temperature measurement unit. Thirty sets of typical temperature field distribution data and five sets of extreme working condition data collected offline were input into the collaborative matching matrix. After simulation and verification by a multiphysics correlation model, all output control parameters were within the safety boundary, and the comprehensive control target value met the preset requirements. The upper and lower limits of the control parameters were locked, and the final construction of the collaborative matching matrix was completed.

[0036] Specifically, the industrial controller inputs the real-time collected temperature and operating condition data of the gridded control units into the collaborative matching matrix. After matrix operation, it outputs the roll gap reduction correction command and tension value correction command corresponding to each control unit. For the temperature deviation region of high temperature and low yield, the roll gap reduction of the corresponding transverse zone and the tension value of the corresponding longitudinal segment are reduced simultaneously. The reduction of the roll gap reduction is positively correlated with the temperature deviation value of the unit, and the reduction of the tension value is positively correlated with the average temperature deviation value of the corresponding longitudinal segment. For the temperature deviation region of low temperature, high yield, and stress concentration, the roll gap reduction of the corresponding transverse zone and the tension gradient of the corresponding longitudinal segment are increased simultaneously. The increase of the roll gap reduction is positively correlated with the absolute value of the temperature deviation and the stress concentration correction coefficient of the unit, and the increase of the tension gradient is positively correlated with the absolute value of the average temperature deviation and the average stress concentration correction coefficient of the corresponding longitudinal segment. The leveling machine roll gap servo system and tension roller servo system execute the correction commands in real time after receiving them, realizing dynamic closed-loop control of multiple fields in the aluminum plate leveling process.

[0037] For example, during the leveling operation, the real-time temperature of a certain grid-controlled unit is 70℃, with a positive deviation of 30℃ from the reference temperature threshold of 40℃. Substituting this into the calibrated downward adjustment coefficient, the total downward adjustment ratio of the roll gap reduction is 7.5%. The initial roll gap reduction of this unit is 0.15mm, and the corrected roll gap reduction is 0.13875mm, which is within the ±30% safety adjustment boundary. The average temperature of the longitudinal segment to which this unit belongs is 65℃, with a positive deviation of 25℃ from the reference threshold. The total downward adjustment ratio of the tension value is 5%, the initial tension value is 20MPa, and the corrected tension value is 19MPa, which is within the ±25% safety adjustment boundary. The real-time temperature of another grid-controlled unit... The initial residual stress amplitude of this unit is relatively high, with a stress concentration correction factor of 1.2. The total upward adjustment ratio of roll gap reduction is 7.2%. The initial roll gap reduction is 0.15 mm, and the corrected roll gap reduction is 0.1608 mm, which is within the safe adjustment boundary. The average temperature of the longitudinal segment to which this unit belongs is 25℃, with a negative deviation of 15℃ from the reference threshold. The average stress concentration correction factor is 1.1, and the total upward adjustment ratio of tension gradient is 0.24% / ℃ × 15℃ × 1.1 = 3.96%. This achieves differentiated and coordinated control of the entire aluminum plate and adapts to the dynamic changes in the material's mechanical properties in different regions.

[0038] Specifically, during the continuous execution of the leveling operation, real-time temperature field data of the aluminum plate after adjustment is continuously collected by an infrared array temperature measurement unit, flatness data of the aluminum plate is collected by an online plate shaper, and residual stress distribution data of the entire aluminum plate is collected by an offline X-ray residual stress detector. The measured plate shape data and residual stress data are compared with the predicted values ​​of the multiphysics correlation model to calculate the prediction deviation value. The deviation data is fed back to the industrial controller to iteratively optimize the constitutive parameters, correction coefficients of the cooperative matching matrix, and cooperative proportioning coefficients of the multiphysics correlation model, continuously improving the model prediction accuracy and control precision. The above process is repeated to form a closed-loop control of the entire process until the leveling operation of the entire roll of aluminum plate is completed.

[0039] For example, during the leveling operation, the measured plate shape data of the aluminum plate is collected every 10m using an online plate shaper. Three sets of samples are taken from the first, middle and last sections of each roll of aluminum plate for offline residual stress detection, and the predicted values ​​of the multiphysics correlation model are compared. When the residual stress prediction deviation is >5%, the mapping relationship between the yield strength temperature decay coefficient β and the residual stress release efficiency is iteratively optimized. When the plate shape error prediction deviation is >10%, the roll gap-tension synergistic ratio coefficient is iteratively optimized.

[0040] Optionally, the method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination further includes infrared temperature measurement data preprocessing and error compensation steps: acquiring the raw temperature measurement data collected by the infrared array temperature measurement unit, using a 5-point moving average filtering algorithm to remove high-frequency noise interference caused by environmental radiation, reflection from the aluminum plate surface oxide film, and vibration of the leveling roller, and combining the surface emissivity calibration parameters of the aluminum plate to be leveled to perform amplitude compensation on the filtered temperature measurement data to obtain high-precision temperature field data after compensation, which is used for subsequent multiphysics model calculation and collaborative matching matrix operation. Specifically, for aluminum plates with different surface conditions, the infrared emissivity within the corresponding temperature range is calibrated in advance using a blackbody furnace, and the emissivity calibration parameters are written into the compensation program of the industrial controller to perform real-time compensation on the raw temperature measurement data, eliminating the temperature measurement error caused by differences in the surface condition of the aluminum plate. For example, for the polished surface of 5052 aluminum alloy, its infrared emissivity is calibrated to 0.12 by a blackbody furnace. After denoising the original temperature measurement data by using a 5-point moving average filter, amplitude compensation is performed by the emissivity parameter. The absolute error of the temperature measurement data after compensation is ≤ ±1℃, which greatly improves the accuracy of temperature field acquisition and ensures the accuracy of subsequent coordinated control.

[0041] Optionally, the method further includes a roll gap servo system response lag compensation step: acquiring the step response data of the leveling machine's roll gap servo system, calibrating the servo system's response time, calculating the advance issuance timing of the control command based on the real-time traveling speed of the aluminum plate, and issuing a correction command to the roll gap servo system according to the advance timing to compensate for the control position deviation caused by the servo system response lag. For example, if the calibrated response time of the leveling machine's roll gap servo system is 20ms, and the real-time traveling speed of the aluminum plate is 1m / s, the corresponding control position deviation is 20mm. Therefore, the industrial controller issues the control command to the roll gap servo system 20mm in advance, completely eliminating the control deviation caused by the servo response lag and ensuring that the control command matches the corresponding position of the aluminum plate.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension, characterized in that, The method includes the following specific steps: S1: Based on the room temperature material mechanical properties of the aluminum plate to be leveled, preset the initial roll gap reduction and initial tension parameters, deploy an infrared array temperature measurement unit in the leveling roll interval, and complete the online debugging of the production line and the temperature measurement system. S2: After the aluminum plate enters the production line, the initial tension is established and continuous leveling is performed. The infrared array temperature measurement unit collects the spatiotemporal distribution data of the two-dimensional temperature field of the aluminum plate in the transverse and longitudinal directions in real time, and collects the production line operating data and transmits it to the industrial controller. S3: Construct a multiphysics field correlation model of deformation heat generation, temperature field evolution, dynamic change of material yield strength, and residual stress release to quantify the dynamic changes of aluminum plate yield strength and elastoplastic deformation threshold in different temperature ranges. S4: Using real-time temperature field distribution as boundary conditions and the control objectives of uniform elimination of residual stress and optimal flatness of the plate, a collaborative matching matrix of dynamic roll gap reduction, tension value and temperature field distribution is constructed. S5: Based on the instructions output by the collaborative matching matrix, the corresponding roll gap reduction and tension value are reduced synchronously for the high temperature and low yield region, and the corresponding roll gap reduction and tension gradient are increased synchronously for the low temperature and high yield stress concentration region, so as to achieve multi-field collaborative dynamic control. S6: Collect temperature field, plate shape and residual stress data of the aluminum plate after regulation, and feed back to optimize the multiphysics correlation model and collaborative matching matrix to form a closed-loop regulation throughout the entire process until the leveling operation is completed.

2. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension as described in claim 1, characterized in that, In S2, the production line operating data includes the aluminum plate traveling speed, the real-time roll gap reduction of each leveling roller, the real-time tension value of the inlet tension roller and the outlet tension roller, and the rotational speed of the leveling roller.

3. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension as described in claim 1, characterized in that, In step S3, the construction of the multiphysics correlation model specifically includes the following steps: Based on the theory of elastic-plastic deformation and the first law of thermodynamics, and combined with the parameters of leveling roll arrangement, roll gap reduction, and aluminum plate travel speed, the amount of deformation heat generated by the aluminum plate during repeated bending deformation in each leveling roll track is calculated; combined with the boundary conditions of heat conduction and heat convection between the aluminum plate and the environment, a temperature field spatiotemporal evolution sub-model is constructed to simulate the dynamic distribution law of the temperature field across the entire aluminum plate. Based on the material properties of the aluminum plate to be leveled, stress-strain curves of the aluminum plate at different temperatures are obtained through high-temperature tensile tests. A quantitative constitutive relationship between the yield strength of the aluminum plate and temperature is established. The constitutive relationship is embedded into the spatiotemporal evolution sub-model of the temperature field to quantify the dynamic decay of the yield strength of the aluminum plate at different temperatures. By combining the dynamic constitutive relation of materials with the theory of residual stress release during aluminum plate leveling, a mapping relationship between different temperatures, different degrees of plastic deformation and residual stress release efficiency is established, and a multi-physics field correlation model is constructed to complete the deformation heat generation, temperature field evolution, dynamic change of material yield strength and residual stress release.

4. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension as described in claim 3, characterized in that, The expression for the yield strength-temperature constitutive relationship of the aluminum plate is as follows: ,in, For temperature Yield strength of the lower aluminum plate room temperature Yield strength of the lower aluminum plate The temperature decay coefficient of yield strength. This refers to the real-time temperature of the aluminum plate. The value is room temperature, taken as 20℃.

5. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension according to claim 1, characterized in that, In step S4, the construction of the collaborative matching matrix specifically includes the following steps: Based on the lateral spatial resolution of the infrared array temperature measurement unit, the partition control capability of the leveling machine roll gap servo mechanism, the aluminum plate travel speed and temperature sampling frequency, the entire surface of the aluminum plate to be leveled is divided into several independent gridded control units. Based on the constructed multiphysics field correlation model, a reference temperature threshold and a safety boundary for the control parameters are set. With the core objective of uniformly eliminating residual stress in aluminum plates and the auxiliary objective of optimizing the flatness accuracy of the plates, a multi-objective control function with constraints is constructed. Based on the multiphysics correlation model, the mapping relationship between the temperature change of aluminum plate and the correction coefficient of roll gap reduction and tension value is calibrated within different temperature deviation ranges. At the same time, the synergistic matching coefficient of roll gap and tension is calibrated. A two-dimensional collaborative matching matrix is ​​constructed using gridded control units as the basic unit, with each matrix element corresponding to a gridded control unit; the update frequency of the matrix is ​​kept consistent with the sampling frequency of the infrared array temperature measurement unit, so as to realize real-time synchronization of input parameters and output commands. The typical temperature field distribution data and extreme working condition data collected offline are input into the constructed collaborative matching matrix. The control effect is simulated through a multiphysics correlation model to verify whether the output control parameters are within the safety boundary and whether they meet the requirements of the multi-objective control function. If the verification fails, the collaborative matching coefficient is recalibrated. If the verification passes, the upper and lower limit thresholds of the control parameters are locked to complete the final construction of the collaborative matching matrix.

6. The method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination according to claim 5, characterized in that, The gridded control unit is divided into N equal-width control zones along the width of the aluminum plate, where N is positively correlated with the number of infrared temperature probes. Each control zone corresponds to at least one set of data collected by the infrared temperature probes. The unit is also divided into several equal-length control segments along the direction of travel of the aluminum plate. The length of each control segment is determined by the ratio of the real-time travel speed of the aluminum plate to the sampling frequency of the infrared array temperature measurement unit.

7. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension as described in claim 5, characterized in that, The expression for the multi-objective control function is: ,in, This represents the residual stress control weighting coefficient. Weights are used to control the plate shape accuracy. The overall control target value; The standard deviation of residual stress for all gridded control units across the entire aluminum plate surface. The full-width panel shape error value of the aluminum plate is defined by the following constraints: the degree of plastic deformation of each unit of the aluminum plate does not exceed the critical strain value of material work hardening, the tension value does not exceed the yield limit of the aluminum plate at the corresponding temperature, and the residual stress control weight coefficient is set to be no less than 0.

6. The sum of the residual stress control weight coefficient and the panel shape accuracy control weight coefficient is 1.

8. The method for eliminating residual stress in aluminum plate leveling based on dynamic roll gap and tension coordination according to claim 5, characterized in that, The reference temperature threshold includes a static reference threshold or a dynamic reference threshold, wherein the static reference threshold is the critical temperature value corresponding to the yield strength of the aluminum plate to be leveled at room temperature, and the dynamic reference threshold is the average temperature value collected in real time across the entire surface of the aluminum plate. The safety boundaries of the control parameters include the roll gap reduction adjustment boundary and the tension value adjustment boundary. The fluctuation range of the roll gap reduction correction value shall not exceed ±30% of the initial roll gap reduction value at the corresponding position, and the fluctuation range of the tension value correction value shall not exceed ±25% of the preset initial tension value of the leveling production line, so as to avoid plate shape defects, aluminum plate tearing or equipment damage caused by exceeding the control parameters.

9. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension according to claim 5, characterized in that, The rows of the two-dimensional collaborative matching matrix correspond to the longitudinal control segments, and the columns of the matrix correspond to the lateral control partitions. The input parameters of the matrix elements include the real-time average temperature of the unit, the temperature deviation value, and the real-time yield strength and residual stress prediction values ​​output based on the multi-physics correlation model. The output parameters include the roll gap reduction correction value and tension value correction value corresponding to the unit.

10. The method for eliminating residual stress in aluminum plate leveling based on the synergy of dynamic roll gap and tension according to claim 5, characterized in that, The temperature deviation is the difference between the real-time temperature of the gridded unit and the reference temperature threshold, and is divided into positive deviation range and negative deviation range. For the positive deviation range, the roll gap reduction coefficient and the tension value reduction coefficient corresponding to each 1°C increase in temperature are calibrated. The reduction in roll gap reduction is positively correlated with the positive temperature deviation value of the unit, and the reduction in tension value is positively correlated with the average positive temperature deviation value of the corresponding longitudinal segment. At the same time, the ratio of the roll gap reduction coefficient to the tension value reduction coefficient is calibrated as the coordination ratio coefficient of the positive deviation range. For the negative deviation range, the adjustment coefficients of roll gap reduction and tension gradient were calibrated for each 1℃ decrease in temperature. The increase in roll gap reduction was positively correlated with the absolute value of the negative temperature deviation of the temperature of the gridded unit and the stress concentration correction coefficient. The increase in tension gradient was positively correlated with the absolute value of the average negative temperature deviation and the average stress concentration correction coefficient of the corresponding longitudinal segment. At the same time, the ratio of the adjustment coefficient of roll gap reduction to the adjustment coefficient of tension gradient was calibrated as the synergistic ratio coefficient for the negative deviation range. The stress concentration correction factor is not less than 1 and is positively correlated with the initial residual stress amplitude of the element.

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