A method for coordinating control of elongation and flatness of a skin pass and straightening mill

Abstract

The application discloses a kind of flatness tension leveler elongation and plate shape coordinated control method, belong to metal material processing and rolling automation control technical field.Flatness tension leveler is equipped with plate shape detection device, tension detection device, elongation detection device and central controller.The method includes: central controller constructs the coupling relationship model of elongation and plate shape parameter;Obtain incoming material plate shape data and process setting target by plate shape detection device;Based on coupling relationship model, using coordinated control strategy determines the target control parameter of elongation and plate shape collaborative matching and issues each actuator;In the process of tension leveler, actual value is collected in real time by each detection device and is dynamically adjusted;When actual elongation or plate shape deviation exceeds threshold value, trigger coordinated correction mechanism, dynamically correct control parameter until meet process requirement.The application realizes the collaborative optimization of elongation and plate shape, improves the control precision of tension leveler process and product quality stability.

Description

Technical Field

[0001] This invention relates to the field of automated control technology for metal material processing and rolling, and more particularly to a method for coordinated control of elongation and plate shape in a leveling and straightening machine. Background Technology

[0002] Leveling and straightening machines are key pieces of equipment in cold-rolled and hot-rolled strip steel finishing production lines, widely used in metal sheet processing in industries such as automotive, home appliances, and construction. By applying a combination of tensile and bending stresses to the strip steel, the leveling machine causes longitudinal elongation within the elastic-plastic deformation range, thereby eliminating shape defects (such as edge waviness, center waviness, and warping) and improving the straightness of the strip. Elongation is one of the most critical control parameters in the leveling process; it is defined as the relative change in length of the strip steel before and after passing through the leveling machine, reflecting the degree of plastic elongation. Precise control of elongation not only affects the strip shape straightening effect but also directly impacts the descaling efficiency of the pickling process.

[0003] In traditional tension leveling control technology, elongation control and shape control are usually two relatively independent processes. Elongation control is mainly achieved by adjusting the speed difference between the inlet and outlet tension roller groups, while shape control is mainly achieved by adjusting the insertion amount (bending amount) of the bending roller group and the straightening roller group. For example, Chinese invention patent document CN104475490A discloses a planetary differential elongation control method. The tension leveling unit using the planetary differential elongation control method achieves high-precision elongation control through the coordinated control of the main drive motor and multiple differential motors. Although this control method achieves precise adjustment of elongation, its control objective focuses solely on elongation itself and does not establish a direct correlation or synergistic optimization mechanism between elongation and shape quality.

[0004] In recent years, with the increasing demands for strip steel product quality, the coordinated control of elongation and shape has gradually attracted attention. Existing research indicates that strip elongation is not only related to the insertion amount of the bending rolls but is also significantly affected by tension. Chinese invention patent document CN122252463A discloses a control method for a tension leveling machine system, which determines a target parameter set based on the strip type. This target parameter set includes both target elongation and target insertion amount. When there is a deviation between the target parameters and the actual effect, the total elongation of the strip is changed by adjusting the bending amount of the bending rolls and the front and rear tensions. While this method reflects the idea of ​​coordinated adjustment of elongation and shape parameters to some extent, its adjustment method still falls under the category of "separate setting and separate adjustment," lacking quantitative modeling and dynamic coordinated control of the coupling relationship between elongation and shape.

[0005] Furthermore, the existing technology has the following shortcomings: First, the adjustment of elongation control and strip shape control often interfere with each other. Adjusting the insertion amount will change the deformation resistance of the strip and thus affect the actual elongation, while adjusting the tension or speed difference may change the strip shape. There is no decoupling mechanism between the two. Second, the existing control methods are mostly static parameter settings or closed-loop adjustment based on single feedback, which are difficult to adapt to dynamic working conditions such as fluctuations in incoming strip shape and changes in material. Third, for special products such as high-strength steel and thin-gauge strip, the contradiction between elongation and strip shape is more prominent. Excessive elongation is beneficial to improving strip shape but may cause surface damage or strip breakage risk, while insufficient elongation is difficult to effectively eliminate strip shape defects. The existing technology has not yet provided an effective coordination solution.

[0006] Therefore, there is an urgent need for a leveling and straightening machine control method that can establish a coupling relationship model between elongation and plate shape and realize dynamic coordinated control of the two. Summary of the Invention

[0007] To address the problem in existing leveling and straightening machine control technologies that elongation control and plate shape control are independent control loops, lacking coupling relationship modeling and collaborative optimization mechanisms, leading to mutual interference between their adjustments and difficulty in adapting to dynamic working conditions, this invention provides a coordinated control method for elongation and plate shape in leveling and straightening machines. The aim is to establish a quantitative coupling model of elongation and plate shape parameters, and to achieve dynamic collaborative optimization of elongation and plate shape through decoupling and coordinated control strategies, thereby improving the control accuracy of the straightening process and the stability of product quality.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for coordinating the elongation and shape of a strip straightening machine, wherein the strip straightening machine includes an inlet tension roller group, a bending roller group, a straightening roller group and an outlet tension roller group arranged in sequence, and the strip undergoes bending deformation and plastic elongation under tension as it passes through the bending roller group and the straightening roller group in sequence.

[0009] The leveling and straightening machine is also equipped with a strip shape detection device, a tension detection device, an elongation detection device, and a central controller. The strip shape detection device is located at the inlet and outlet sides of the leveling and straightening machine to detect the incoming strip shape data and the actual strip shape data. The tension detection device is located at at least one of the following locations: in front of the inlet tension roller group, between the bending roller group and the straightening roller group, and behind the outlet tension roller group, to detect the strip tension value in real time. The elongation detection device is located at the inlet tension roller group and the outlet tension roller group, respectively, and calculates the actual elongation by detecting the inlet speed and the outlet speed. The central controller is signal-connected to the inlet tension roller group, the outlet tension roller group, the bending roller group, the straightening roller group, and each detection device to execute the coordinated control method.

[0010] The coordination and control method includes the following steps: S1, the central controller acquires the equipment parameters of the leveling and straightening machine and the incoming parameters of the strip steel, and constructs a coupling relationship model between the elongation and the shape parameters; the coupling relationship model at least characterizes the quantitative mapping relationship between the elongation and the bending roll insertion amount, the straightening roll insertion amount, the inlet tension, and the outlet tension, as well as the mutual influence coefficients between the parameters.

[0011] S2, the central controller acquires the incoming strip shape data before the strip enters the leveling and straightening machine through the strip shape detection device. The incoming strip shape data includes at least the transverse thickness distribution, wave type and wave amplitude of the strip. It also acquires the user-preset process setting target, which includes at least the target flatness requirement and the target elongation range.

[0012] S3, the central controller uses the incoming material shape detection data and process setting target obtained in S2 as input conditions, and combines them with the coupling relationship model constructed in S1 to output the control parameters of each actuator using a coordinated control strategy; the coordinated control strategy includes: Based on the type and severity of defects in the incoming sheet shape, determine the initial insertion amount allocation scheme for the bending roller group and straightening roller group required for sheet shape correction; Based on the initial insertion amount allocation scheme, the tension setting value and the corresponding elongation estimate required to achieve the target plate shape under the insertion amount condition are calculated in reverse based on the coupling relationship model. Determine whether the estimated elongation rate falls within the user's preset target elongation rate range: if it does, then the set of control parameters is determined as the target control parameters; if it does not, then adjust the matching relationship between the insertion amount allocation scheme and the tension setting value until the estimated elongation rate falls within the target elongation rate range and the plate shape correction effect meets the preset requirements, thereby determining a set of target control parameters for coordinated matching of elongation rate and plate shape.

[0013] S4, the central controller sends the target control parameters determined in S3 to the actuators of the inlet tension roller group, outlet tension roller group, bending roller group, and straightening roller group, respectively, so that each actuator operates in coordination according to the target control parameters; during the tension straightening process, the actual tension value is collected in real time by the tension detection device, the actual elongation data is collected in real time by the elongation detection device, and the actual strip shape data is collected in real time by the strip shape detection device, and the control parameters of each actuator are dynamically adjusted according to the deviation between the actual value and the target value.

[0014] S5, during the straightening process, when the deviation between the actual elongation detected by the elongation detection device and the target elongation exceeds a first preset threshold, or the deviation between the actual strip shape detected by the strip shape detection device and the target strip shape exceeds a second preset threshold, the central controller triggers a coordination correction mechanism; the coordination correction mechanism includes: calculating the insertion correction amount and / or tension correction amount based on the coupling relationship model according to the real-time deviation direction and amplitude, and dynamically correcting the current control parameters with the constraint of prioritizing ensuring the flatness of the strip shape meets the requirements while controlling the elongation deviation within the allowable range, until the elongation and strip shape simultaneously meet the process requirements.

[0015] Preferably, the strip shape detection device has multiple measurement sections distributed along the width direction of the strip, which are used to detect the transverse stress distribution of the strip in real time and calculate the amplitude and type of various strip shape defects accordingly.

[0016] Preferably, the elongation detection device includes inlet tension rollers and outlet tension rollers respectively. The actual elongation is calculated by detecting the linear velocity of the inlet tension rollers and the linear velocity of the outlet tension rollers using the following formula:

[0017] In the formula, The linear velocity of the strip measured by the inlet tension roller group. The strip speed is measured by the exit tension roller group.

[0018] Preferably, the tension detection devices are respectively installed in front of the inlet tension roller group, in front of and behind the bending roller group, and in rear of the outlet tension roller group, for real-time detection of the strip tension value at each key position.

[0019] Preferably, the coupling relationship model described in S1 further characterizes the first influence coefficient of the bending roller insertion amount on the actual elongation, the second influence coefficient of the tension change on the plate curvature, and the cross-coupling coefficient between elongation and plate shape. The main controlling factor between elongation and plate shape is determined by the ratio of the first influence coefficient and the second influence coefficient, and the priority adjustment direction of coordinated control is determined based on the main controlling factor.

[0020] Preferably, the coordinated control strategy in S3 further includes: when the plate shape defect is an edge wave, the insertion amount of the bending roller group is increased first and supplemented by tension fine adjustment; when the plate shape defect is a middle wave, the insertion amount of the straightening roller group is adjusted first and supplemented by tension fine adjustment; when the plate shape defect is a composite wave, a coordinated control method is adopted in which the bending roller group and the straightening roller group are jointly adjusted and the tension setting is matched synchronously.

[0021] Preferably, the coordination and correction mechanism described in S5 further includes: when there is a conflict between the adjustment directions of elongation deviation and shape deviation, introducing a predefined priority rule or weighted optimization strategy to determine the comprehensive adjustment amount. Specifically, when the elongation is close to the upper limit of the target elongation and there are obvious defects in the shape, shape adjustment is given priority and the elongation is allowed to increase moderately within the target range; when the elongation is close to the lower limit of the target elongation and the shape defect is minor, elongation stability is given priority.

[0022] Preferably, the method further includes: the central controller records the incoming material parameters, target control parameters, actual operating data and product quality results for each straightening task and stores them in the process knowledge base; when processing similar incoming materials later, the central controller performs initial matching of control parameters based on historical successful cases in the process knowledge base to shorten the convergence time of coordinated control.

[0023] The beneficial effects of this invention are as follows: 1. This invention breaks through the technical barrier of independent elongation control and plate shape control in traditional control by constructing a coupling relationship model between elongation and plate shape parameters. It achieves coordinated matching and joint optimization of elongation and plate shape, avoiding interference from adjusting one parameter on the other, and significantly improving the overall control accuracy of the tension straightening process. Compared with traditional control methods, the elongation control accuracy can reach within ±0.02%, and the plate flatness can be controlled within 2 mm / m.

[0024] 2. Based on the coupling relationship model, this invention introduces a coordinated control strategy and a dynamic correction mechanism. When the incoming material conditions or process conditions change, it can quickly determine the direction and magnitude of the deviation between the elongation rate and the plate shape based on real-time feedback, and calculate the optimal comprehensive adjustment amount. This enables the system to have the ability to adapt to dynamic conditions, effectively reducing product quality fluctuations and scrap rates caused by fluctuations in operating conditions.

[0025] 3. This invention has developed differentiated coordinated control strategies for different types and severity of plate shape defects, such as prioritizing the adjustment of the bending roller insertion amount for edge waviness and prioritizing the adjustment of the straightening roller insertion amount for center waviness. This makes the control decision more accurate and efficient, reduces unnecessary parameter adjustments, and improves the response speed and stability of the control system. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a leveling and straightening machine structure provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating a method for coordinating the control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating the method S1 for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Figure 4 This is a flowchart illustrating the method S3 for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Figure 5 This is a flowchart illustrating S5 of a method for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0028] Figure 1 A schematic diagram of a leveling and straightening machine structure according to an embodiment of the present invention is shown below. Please refer to [link / reference]. Figure 1 As shown, the leveling and straightening machine according to an embodiment of the present invention consists of the following main parts, including an inlet tension roller group, a bending roller group, a straightening roller group and an outlet tension roller group arranged in sequence.

[0029] An inlet tension roller group and an outlet tension roller group are sequentially arranged along the strip's running direction. The inlet tension roller group consists of three tension rollers (1, 2, 3), and the outlet tension roller group consists of three tension rollers (4, 5, 6). Each tension roller is driven by an independent AC variable frequency motor and equipped with a high-precision rotary encoder (accuracy ±0.01%) to detect the actual rotational speed of each roller in real time. The inlet tension roller group is used to establish a stable inlet tension before the strip enters the bending roller group, and the outlet tension roller group is used to establish the outlet tension. The longitudinal extension of the strip is achieved through the speed difference between the inlet and outlet tension roller groups.

[0030] Located between the inlet and outlet tension roller groups along the strip's running direction, a first bending roller group, a second bending roller group, and a straightening roller group are sequentially arranged. Each bending roller group consists of an upper row of work rollers and a lower row of work rollers. The upper row of work rollers is driven by a hydraulic cylinder or an electric servo cylinder to achieve vertical position adjustment, i.e., adjustment of the insertion amount. The insertion amount adjustment range for the first bending roller group is 0~40mm, for the second bending roller group it is 0~35mm, and for the straightening roller group it is 0~30mm. Each adjustment mechanism is equipped with a high-precision displacement sensor (accuracy ±0.01mm) for real-time feedback of the actual insertion amount.

[0031] The strip shape detection device is located at the entrance side of the leveling and straightening machine. It adopts a segmented strip shape measuring roller with 25 to 45 measuring sections distributed along the width direction of the strip. It detects the transverse stress distribution of the strip in real time and calculates the amplitude and type of various strip shape defects such as edge waves, middle waves, and composite waves.

[0032] The tension detection device is a piezomagnetic tension meter or a resistance strain gauge tension meter with an accuracy of ±0.5%FS, and is respectively installed before the inlet tension roller group, before and after the bending roller group, and after the outlet tension roller group.

[0033] The elongation detection device detects the strip's inlet and outlet speeds using high-precision rotary encoders installed on the inlet and outlet tension roller sets, respectively. The actual elongation calculation formula is as follows:

[0034] In the formula, The linear velocity of the strip measured by the inlet tension roller group. The strip speed is measured by the exit tension roller group.

[0035] A central controller (PLC or industrial computer) is set up and connected to the aforementioned tension roller drive motors, servo adjustment mechanisms, and detection devices. The central controller operates the coordinated control method of this invention, dynamically adjusting each actuator based on real-time feedback from the detection devices.

[0036] Figure 2 A flowchart illustrating a method for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention is shown. Please refer to [link / reference]. Figure 2 Specifically, it includes the following steps: S1. Establish a coupling relationship model between elongation and plate shape parameters. Figure 3 The diagram shows a flow chart of a method S1 for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Please refer to [link / reference]. Figure 3 The details are as follows: S11, the central controller acquires the inherent parameters of the leveling and straightening machine in this embodiment, including: the roller diameter of each tension roller, the roller diameter and center distance of each working roller in the bending roller group, the roller diameter and center distance of each working roller in the straightening roller group, the stroke range and response speed of each adjustment mechanism, and the rated power and rated torque of each drive motor, etc.

[0037] The central controller acquires the incoming parameters of the current batch of strip steel, including: strip steel grade (DC01), thickness (1.0 mm), width (1250 mm), yield strength (measured as 210 MPa), tensile strength (measured as 340 MPa), elastic modulus (206 GPa), and the incoming strip shape data measured by the strip shape detection device.

[0038] S12, the central controller, based on the principles of elastoplastic mechanics and metal bending theory, constructs a coupling relationship model between elongation and strip shape parameters. During the leveling and tensioning process, the total elongation of the strip is composed of the following three superimposed parts:

[0039] in, The total elongation of the strip after passing through the tension leveler; These are the elastic and plastic elongation components under tension alone, and are related to the inlet tension, outlet tension, and the yield strength and elastic modulus of the strip. The extension component resulting from the bending action of the bending roll group and the straightening roll group is related to the insertion amount of each roll group; It represents the cross-coupled extension component under the combined action of tension and bending, reflecting the interaction between tension and bending.

[0040] In this embodiment, after appropriate simplification of the above theoretical model, the following quantitative relationship is established:

[0041] in, The difference between the inlet tension and the outlet tension is the effective tensile tension (in MPa). This refers to the insertion amount of the first bending roller group. This refers to the insertion amount of the second bending roller group. The insertion amount of the straightening roller group (all dimensions are mm). ~ The main effect coefficients of each factor (dimensions % / mm) are determined through theoretical calculations or experimental calibration. , is the cross-coupling coefficient (dimensions % / MPa·mm), which characterizes the nonlinear coupling effect between tension and bending; This is a correction term used to compensate for model errors.

[0042] It should be noted that the main effect coefficients mentioned above... ~ and cross-coupling coefficient , It is not a fixed constant; its value is strongly related to the specific equipment structure of the leveling and straightening machine (such as the roller diameter, roller length, and roller arrangement), the material properties of the strip (such as yield strength σs, elastic modulus E, and work hardening index), and its geometric specifications (such as strip thickness h and width B). The typical calibration values ​​given in this embodiment (α1≈0.015, etc.) are applicable to working conditions with strip thickness in the range of 0.8mm to 1.5mm, yield strength in the range of 200MPa to 400MPa, and specific roller specifications.

[0043] When dealing with strip steel of different specifications or materials, the coefficients need to be adjusted accordingly as follows: Based on equipment specifications: If the roller diameter or roller spacing of the equipment changes, the bending correlation coefficient is scaled proportionally according to the principle of geometric similarity of bending moment. Nonlinear correction based on material properties: A material correction factor is introduced. When the yield strength of the strip deviates from the calibration benchmark value, the change rate of deformation resistance is calculated using the elastic-plastic bending theory. The values ​​of each main effect coefficient are adjusted accordingly. Generally, the harder the material, the smaller the elongation generated by the unit tension or insertion amount, and the corresponding coefficients need to be reduced accordingly. Thickness correction based on specifications: For variations in strip thickness, the effect coefficient of bending insertion is normalized according to the influence of thickness on the position of the bending neutral layer, ensuring the prediction accuracy of the model under different thickness specifications.

[0044] The above adjustment mechanism ensures the applicability and control accuracy of the coupling relationship model under varying operating conditions.

[0045] Meanwhile, the relationship between the strip shape parameters (characterized by the uniformity of stress distribution on the cross-section of the strip) and the aforementioned control parameters is as follows:

[0046] in, ~ This is the adjustment coefficient for the plate shape based on the insertion amount of each roller group; This is the coefficient representing the influence of tension difference on plate shape. Q is the correction term, which is the strip shape quality index. It is defined as the root mean square (RMS) value of the deviation between the measured residual stress and the average stress at each measuring point along the width direction of the strip. The unit is MPa. It is used to quantitatively characterize the severity of strip shape defects. The smaller the Q value, the more uniform the internal stress distribution of the strip and the flatter the strip shape. The conversion relationship between the plate shape quality index Q and the plate shape flatness (unit mm / m) is derived based on Hooke's Law, and the specific formula is as follows:

[0047] Where L is the flatness index (mm / m), i.e., the relative wave height; L0 is the strip length under investigation (usually taken as 1000mm); E is the elastic modulus of the strip (taken as 206GPa in this embodiment); and h is the strip thickness. This conversion relationship transforms the unevenness of internal stress distribution into an intuitive external geometric shape index, facilitating comparison with the flatness requirements set by the process (e.g., ≤2mm / m).

[0048] S13, the central controller calibrates the coefficients in the above model using offline experiments or prior production data.

[0049] To calibrate the cross-coupling coefficient, an orthogonal experimental design method was used to conduct multi-factor coupling experiments. The specific process is as follows: First, the insertion amount of the first bending roller group, the insertion amount of the second bending roller group, the insertion amount of the straightening roller group, and the tension difference were selected as experimental factors, and multiple level values ​​were set for each factor. Design multiple experimental schemes based on orthogonal arrays, keep other interference factors constant during the experiment, and collect the actual elongation data and plate shape quality index data corresponding to each experimental scheme. Based on the collected experimental data, multiple linear regression or nonlinear fitting algorithms are used to identify and solve the main effect coefficients and cross-coupling coefficients in the coupling relationship model, thereby determining the specific values ​​of each coefficient.

[0050] The main effect coefficient can be determined through a single-factor experiment: that is, keep other parameters constant, adjust a certain control variable (such as adjusting only the insertion amount of the first bending roller group), record the corresponding changes in elongation and shape, and calculate the main effect coefficient of the variable accordingly.

[0051] After calibration, the typical values ​​of the above coefficients in this embodiment are as follows (these values ​​may vary depending on the equipment and operating conditions): ≈0.015 (% / MPa) ≈0.012 (% / mm) ≈0.009 (% / mm) ≈0.006 (% / mm) ≈0.0008 (% / MPa·mm), ≈0.0005 (% / MPa·mm), ≈0.35, ≈0.25, ≈0.40, ≈0.015.

[0052] It should be noted that the cross-coupling coefficient (Dimensions are % / MPa·mm) and (Dimensions in MPa) and Multiplying the products (in mm), the dimensional calculation is (% / MPa·mm) × MPa × mm = %, the dimensions are canceled and reduced, and the cross-coupling coefficient is obtained. The same principle applies to dimensional calculations.

[0053] S2, obtain the incoming strip shape detection data and the user-preset process setting target. In this embodiment, the central controller measures the incoming strip shape data through the strip shape detection device on the inlet side as follows: the edge wave amplitude is about 10I (about 2.5mm / m), the middle wave amplitude is about 3I (about 0.75mm / m), which belongs to the composite wave shape defect dominated by the edge wave.

[0054] The user-preset process settings are: target plate flatness ≤ 2mm / m; target elongation range 0.8%~1.2%, with the preferred target elongation setting value being 1.0%.

[0055] S3, based on a coupling relationship model, makes coordinated control decisions. Figure 4 The diagram shows a flow chart of method S3 for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Please refer to [link / reference]. Figure 4 The details are as follows: S31, the central controller determines the initial insertion amount allocation scheme based on the incoming plate shape defects (compound waviness mainly composed of edge waviness) identified by the plate shape detection device. According to a predetermined coordinated control strategy: edge waviness is preferentially adjusted by regulating the insertion amount of the bending roller group, while the middle waviness is assisted by regulating the insertion amount of the straightening roller group. The central controller generates the initial insertion amount allocation scheme as follows: Based on the edge wave amplitude (10I) and strip thickness (1.0mm), the initial insertion amount I of the first bending roll group is determined by empirical formula or by consulting the process rule library. b1 _0=28mm, initial insertion depth I of the second bending roller group b2 _0=22mm; Based on the mid-wave amplitude (3I), determine the initial insertion amount I of the straightening roller group. s _0=18mm.

[0056] S32, the central controller uses the initial insertion amount allocation scheme (I) determined in S31. b1 _0=28mm, I b2 _0=22mm, I s Using _0=18mm as input, and combining the current working parameters, based on the coupling relationship model established by S1, the tension difference required to achieve the target plate shape is calculated in reverse. And calculate the corresponding estimated elongation rate.

[0057] In this embodiment, the plate shape relationship in the coupling model gives the plate shape quality index Q and tension difference under a given insertion amount. The correspondence between them. Using the Q value corresponding to a target plate flatness ≤ 2mm / m as a constraint, the central controller solves for the required minimum tension difference. ≈85MPa, and under this tension condition, the corresponding elongation estimate ε_pred≈1.35% was calculated.

[0058] S33, determine whether the estimated elongation rate falls within the target range and make adjustments accordingly. The central controller determines whether the estimated elongation rate ε_pred≈1.35% falls within the target elongation rate range of 0.8%~1.2%, and the result is that it exceeds the upper limit (1.35%>1.2%).

[0059] The central controller triggers an adjustment and matching mechanism. Based on the analysis of the influence coefficients in the coupling model, to reduce the estimated elongation rate to the target range, the tension difference setting can be reduced, but this may decrease the shape correction effect. Reducing the insertion amount of the bending roller group can decrease the elongation component caused by bending deformation, while appropriately increasing the insertion amount of the straightening roller group can compensate for the shape correction effect. The combined approach of these two methods is superior to a single adjustment.

[0060] The central controller employs an iterative optimization algorithm based on gradient descent for parameter optimization, specifically implemented as follows: S331, Construct the evaluation function: Construct a weighted evaluation function that includes elongation deviation and shape deviation, wherein the elongation weight coefficient and the shape weight coefficient are determined according to the process requirements; S332, Set step size: Set the adjustment step size of the first bending roller group, the second bending roller group, the straightening roller group, and the tension difference; S333, Iterative calculation: Based on the current control parameters, the gradient direction of elongation and plate shape is calculated using the coupling relationship model. Along the direction that reduces the value of the evaluation function, each control parameter is updated according to the set adjustment step size. S334, Convergence Judgment: Repeatedly adjust the matching mechanism until the estimated elongation rate falls within the target elongation rate range, and the flatness of the plate meets the preset requirements, or the value of the evaluation function is less than the preset convergence threshold.

[0061] After iterative optimization calculations, the adjusted target control parameters output by the central controller are as follows: Inlet tension set at 45 MPa, outlet tension set at 135 MPa, tension difference =90MPa (reduced from the initial value to decrease elongation), first bending roller insertion amount: =26mm (2mm less than the initial value), second bending roller insertion amount: =20mm (2mm less than the initial value), straightening roller insertion amount: =20mm (2mm larger than the initial size).

[0062] Substituting the above parameters into the coupling relationship model for verification calculation, we obtained: the estimated elongation ε_pred≈1.15%, which falls within the target elongation range of 0.8%~1.2%; the estimated flatness of the plate is about 1.5mm / m, which meets the requirement of ≤2mm / m.

[0063] S4, the central controller sends the target control parameters determined in S3 to the corresponding actuators via industrial Ethernet: The drive frequency converter of the inlet tension roller group receives the inlet tension set value of 45MPa and converts it into torque commands for each motor. The frequency converter driving the outlet tension roller group receives the outlet tension set value of 135MPa and converts it into torque commands for each motor. The servo adjustment mechanism of the first bending roller group receives the insertion amount setting value of 26mm and drives the hydraulic cylinder or electric cylinder to move into position. The servo adjustment mechanism of the second bending roller group receives the insertion amount setting value of 20mm and moves into position; The servo adjustment mechanism of the straightening roller group receives the insertion amount setting value of 20mm and moves into place.

[0064] Upon receiving control commands, each actuator operates synchronously. Each adjustment mechanism forms a position closed-loop control through built-in displacement sensors, ensuring that the deviation between the actual position and the set value does not exceed ±0.05mm. Each tension roller forms a speed closed-loop control through a rotary encoder, ensuring that the deviation between the actual speed and the set speed of each roller does not exceed ±0.05%. Under the control of the above parameters, the strip steel passes stably through the tension leveler, undergoing plastic elongation under the combined action of tension and bending, thus correcting strip shape defects.

[0065] During the tension straightening process, the central controller collects the actual tension value in real time through the tension detection device, the actual elongation data in real time through the elongation detection device, and the actual strip shape data in real time through the strip shape detection device. Based on the deviation between the actual value and the target value, the controller dynamically adjusts the control parameters of each actuator.

[0066] S5 is based on dynamic correction and adaptive coordination with real-time feedback. Figure 5 The diagram shows a flow chart of S5, a method for coordinated control of elongation and plate shape in a leveling and straightening machine according to an embodiment of the present invention. Please refer to [link / reference]. Figure 5 The details are as follows: S51, during the straightening process, the central controller collects the actual strip shape data in real time through the strip shape detection device, calculates the actual elongation in real time through the elongation detection device, and detects the tension value at each key position in real time through the tension detection device.

[0067] The determination of the first and second preset thresholds follows the general principles below: The first preset threshold is dynamically determined based on the strip material characteristics and the target elongation setting, typically ±5% to ±15% of the target elongation setting; for high-strength steel with a yield strength higher than 400MPa, the threshold is set to the lower limit (e.g., ±5%) to prevent the risk of strip breakage due to over-elongation; for ordinary low-carbon steel, the threshold can be set to the upper limit; The second preset threshold is determined based on the finished plate shape quality grade requirements and strip thickness, typically set to 15% to 25% of the target plate shape flatness index; when the strip thickness is less than 1.0mm, the threshold is reduced accordingly because thin plates are sensitive to defects; at the same time, a control stability constraint is introduced, and when the tension fluctuation variance exceeds the preset range, the threshold is automatically amplified to avoid frequent action of the actuator causing system oscillation.

[0068] In this embodiment, the central controller detected the following deviation during the stable operation phase: The actual elongation rate was 1.22%, which deviated from the target value of 1.0% by 0.22%, exceeding the first preset threshold (based on the ordinary low-carbon steel material in this embodiment, it is set to ±0.15%, i.e. ±15% of the target value). The actual flatness of the board is 2.3 mm / m, which is 0.3 mm / m away from the target value of ≤2 mm / m. This exceeds the second preset threshold (which is set to 0.2 mm / m, i.e. 10% of the target value, based on the quality requirements of the appliance board in this embodiment). The edge waves were basically eliminated (about 0.5 mm / m), but the middle waves were not corrected enough (about 1.8 mm / m). The actual plate shape defect type changed from edge waves in the incoming material to residual middle waves after straightening.

[0069] S52, since both elongation and shape exceed the allowable deviation range, the central controller triggers a coordinated correction mechanism. Based on the current shape defect type (residual waviness), and combined with the influence coefficients revealed by the shape relationship formula in the S1 coupling model (the straightening roller insertion amount has the highest adjustment efficiency for waviness), the correction strategy is determined to be: increasing the straightening roller insertion amount as the main correction method.

[0070] Specifically, the adjustment step size is first determined. Based on the influence coefficient of the straightening roller insertion amount on the plate shape in the coupling relationship model, and combined with the difference between the current plate shape deviation and the target value, the required initial adjustment amount is calculated. At the same time, the system response time constant is introduced as a constraint, and the maximum step size threshold for a single adjustment is set. The smaller value between the calculated required adjustment amount and the maximum step size threshold is taken as the "gradually increasing" step size to avoid system overshoot or oscillation caused by excessive step size, and to ensure a smooth transition in the correction process.

[0071] Secondly, the tension reduction range is determined. Based on the first influence coefficient of tension difference on elongation and the cross-coupling coefficient of straightening roller insertion amount on elongation in the coupling relationship model, the elongation increment caused by the increase in straightening roller insertion amount at the current step length is calculated. According to this elongation increment, the tension difference to be reduced is calculated using a reverse compensation algorithm, i.e., tension reduction range = elongation increment / first influence coefficient, so as to achieve precise hedging against changes in elongation and ensure that the elongation is stable within the target range.

[0072] Therefore, the central controller will determine the insertion amount of the straightening roller assembly. Based on the current value of 20mm, gradually increase the step size as determined above, while appropriately reducing the tension difference according to the calculated range above to offset the increase in elongation.

[0073] S53, while keeping the strip running, the central controller executes the following iterative correction loop: First correction: Adjust the insertion amount of the straightening roller group. The elongation was increased from 20mm to 22mm, while the outlet tension setting was slightly reduced from 135MPa to 132MPa (the tension difference decreased accordingly from 90MPa to 87MPa). After correction, the central controller, through various detection devices, showed an actual elongation of 1.18% and a flatness of 1.9mm / m. The elongation is still slightly higher than the target but falls within the allowable deviation range of ±0.15%, and the flatness meets the requirement of ≤2mm / m.

[0074] At this point, although both the elongation and the flatness meet the basic process requirements, the central controller determines that the deviation direction between the current actual elongation and the target setpoint of 1.0% is stable, and the current flatness still has room for further optimization as it is far from the target upper limit. Therefore, the central controller does not immediately terminate the correction, but instead locks the current tension setpoint and initiates a gradient-based fine-tuning program. Under the premise of ensuring that the elongation does not exceed the allowable deviation boundary, it attempts to further improve the flatness to approach the optimal target value.

[0075] Second correction (in the next control cycle, based on continuous monitoring data): Considering that there is still room for fine-tuning the sheet shape after increasing the insertion amount of the straightening rollers, and that the elongation is already within the allowable range, the central controller will adjust the insertion amount of the straightening roller group. The diameter was finely adjusted from 22mm to 23mm, while the outlet tension remained unchanged (132MPa). After correction, the central controller was tested by various detection devices: the actual elongation was 1.21%, the plate flatness was 1.7mm / m, the elongation remained within the allowable deviation range, and the plate flatness was further improved, achieving a better control state.

[0076] S54, when the elongation and plate shape simultaneously meet the process requirements and the system operates continuously and stably for more than a set time (e.g., 2 minutes), the central controller locks the current control parameters, i.e., the inlet tension value is 45MPa and the outlet tension value is 132MPa. =26mm, =20mm, =23mm) is used as the final control parameter for this batch of strip steel, and this set of parameters, along with the corresponding incoming material information and actual operating results, are stored in the process knowledge base.

[0077] After successful tension straightening in this embodiment, the central controller automatically records the data from this task as a structured case and stores it in the process knowledge base. The case content includes: Incoming material identification information: grade DC01, thickness 1.0mm, width 1250mm, yield strength 210MPa; Incoming material plate shape characteristics: edge wave amplitude 10I, middle wave amplitude 3I; Initial target settings: target elongation 0.8%~1.2%, target plate flatness ≤2mm / m; The final coordinated control parameters adopted are: inlet tension 45 MPa and outlet tension 132 MPa. =26mm, =20mm, =23mm; Actual performance indicators achieved: average elongation of 1.19% after stabilization, and flatness of 1.7 mm / m.

[0078] When producing similar or identical strip steel (e.g., the same grade, similar thickness), the central controller first searches for similar cases in the process knowledge base before initiating the coordinated control decision in S3. If a historical case with a similarity higher than the set threshold is found, the control parameters recorded in the historical case are directly used as reference values ​​for the initial insertion amount allocation scheme in S31 and the initial tension setting in S32, thereby shortening the iterative convergence time of the coordinated control.

[0079] The similarity calculation employs a weighted Euclidean distance method based on multidimensional feature vectors. First, a feature vector is constructed containing the strip grade, thickness, width, yield strength, and incoming strip shape characteristics. Each feature parameter is normalized to eliminate dimensional differences, and weight coefficients are assigned according to the sensitivity of each parameter to the tension leveling process, with the thickness and yield strength having higher weight coefficients. Calculate the weighted Euclidean distance D between the current operating condition feature vector and the historical case feature vector, and define the similarity as S = 1 / (1+D), where S ranges from 0 to 1, with a larger value indicating higher similarity. The set threshold is determined based on the initial control accuracy requirements, typically ranging from 0.85 to 0.95. When the calculated similarity S is greater than the set threshold, the historical case is considered a successful match; otherwise, it is considered that there is no matching case, and the default strategy is still used for initial parameter calculation.

[0080] During the aforementioned collaborative operation, the strip shape detection device, tension detection device, and elongation detection device collect strip shape, tension, and elongation data in real time and feed them back to the central controller. Based on the coupling relationship model and coordinated control strategy, the central controller outputs control commands to the actuators of the inlet tension roller group, outlet tension roller group, bending roller group, and straightening roller group, forming a complete closed-loop control link of "perception-decision-execution".

[0081] The above embodiment uses a composite wave-shaped defect dominated by edge waves as an example for illustration. This method is also applicable to other types of plate-shaped defects, requiring only adaptive adjustments to the initial insertion allocation strategy in S3 and the selection of the correction direction in S5, as follows: When the incoming material's shape defect is mainly a central wave, the initial insertion amount allocation scheme in S31 is adjusted to: prioritize increasing the insertion amount of the straightening roller group, with the insertion amount of the bending roller group used as an auxiliary adjustment method. The correction strategy in S52 is adjusted to: when the residual shape defect is a central wave, prioritize adjusting the insertion amount of the straightening roller group; when the residual defect is an edge wave, prioritize adjusting the insertion amount of the bending roller group; when there are compound defects, adopt a coordinated correction method that combines the adjustment of the bending roller group and the straightening roller group.

[0082] When the incoming strip steel is high-strength steel (yield strength ≥ 400 MPa), considering that high-strength steel has a large deformation resistance and is more sensitive to elongation control, the target elongation range in S3 should be appropriately narrowed (e.g., ±0.1%), and the first preset threshold for elongation deviation in S5 should also be reduced accordingly to ensure that no surface damage or strip breakage risk occurs due to over-elongation during the high-strength steel straightening process.

[0083] To verify the adaptability of the proposed method to high-strength steel conditions, a simulation verification experiment was conducted using HC420LA strip steel with a measured yield strength of 450 MPa and a thickness of 1.2 mm. The target elongation was set at 0.5% (allowable deviation ±0.05%), and the incoming strip shape was set to a medium wave amplitude of 15I. The central controller, based on the material correction factor calculation model in S1, automatically reduced the main effect coefficient by approximately 30% and output the initial control scheme: straightening roll insertion of 25 mm and tension difference of 45 MPa. Simulation results showed that the actual elongation remained stable at 0.49%, the strip flatness improved to 1.5 mm / m, no tension over-limit alarm was triggered throughout the process, and the maximum elongation fluctuation was only 0.02%. These experimental data demonstrate that, through the introduction of the material correction factor and the adaptive adjustment of the model coefficients, this method maintains good prediction accuracy and control stability under high-strength steel conditions, effectively solving the problems of easy breakage of high-strength steel strips during tension straightening and the difficulty in controlling surface quality.

[0084] The adjustments to the coordinated control strategies under the aforementioned operating conditions are all automatically determined and executed by the central controller based on the plate shape defect type and amplitude identified by the plate shape detection device, without the need for manual intervention. The tension detection device and elongation detection device operate continuously under all operating conditions, providing real-time feedback data for the coupling relationship model and coordinated correction mechanism.

[0085] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for coordinated control of elongation and shape in a leveling and straightening machine, the leveling and straightening machine comprising an inlet tension roller group, a bending roller group, a straightening roller group, an outlet tension roller group, a shape detection device, a tension detection device, an elongation detection device, and a central controller, characterized in that, include: Based on the equipment parameters of the leveling and straightening machine and the incoming parameters of the strip steel, a coupling relationship model between elongation and strip shape parameters is constructed. The coupling relationship model at least characterizes the quantitative mapping relationship between elongation and bending roll insertion amount, straightening roll insertion amount, inlet tension, and outlet tension, as well as the mutual influence coefficients between each parameter. The strip shape detection device acquires the incoming strip shape data and the user-preset process setting target. Using the incoming strip shape data and the process setting target as input conditions, and combined with the coupling relationship model, a coordinated control strategy is adopted to determine the target control parameters for the coordinated matching of elongation and strip shape, and then distributes them to each actuator. During the straightening process, the actual values ​​are collected in real time by various detection devices and dynamically adjusted. When the actual elongation or plate shape deviation exceeds the threshold, the coordination correction mechanism is triggered. Based on the coupling relationship model, the insertion correction amount and tension correction amount are calculated. The control parameters are dynamically corrected to ensure that the plate shape flatness meets the requirements and that the elongation deviation is controlled within the allowable range, so as to ensure that the elongation and plate shape meet the process requirements at the same time.

2. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, The coupling relationship model also characterizes the first influence coefficient of the bending roller insertion amount on the actual elongation, the second influence coefficient of the tension change on the plate curvature, and the cross-coupling coefficient between elongation and plate shape; the main control factor between elongation and plate shape is determined by the ratio of the first influence coefficient and the second influence coefficient, and the priority adjustment direction of coordinated control is determined according to the main control factor.

3. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 2, characterized in that, The coordinated control strategy includes: determining the initial insertion amount allocation scheme of the bending roller group and straightening roller group required for plate shape correction based on the type and severity of the incoming plate shape defects; calculating the tension setting value and corresponding elongation estimate required to achieve the target plate shape under the insertion amount condition based on the coupling relationship model according to the initial insertion amount allocation scheme; determining whether the elongation estimate falls within the user-preset target elongation range; if not, adjusting the matching relationship between the insertion amount allocation scheme and the tension setting value until the elongation estimate falls within the target elongation range and the plate shape correction effect meets the preset requirements, thereby determining the target control parameters.

4. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 3, characterized in that, The coordinated control strategy also includes: when the plate shape defect is an edge wave, the insertion amount of the bending roller group is increased first and supplemented by tension fine adjustment; when the plate shape defect is a middle wave, the insertion amount of the straightening roller group is adjusted first and supplemented by tension fine adjustment; when the plate shape defect is a composite wave, a coordinated control method is adopted in which the bending roller group and the straightening roller group are jointly adjusted and the tension setting is matched synchronously.

5. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, The coordination and correction mechanism includes: calculating the insertion correction amount and tension correction amount based on the coupling relationship model according to the real-time deviation direction and amplitude; when there is a conflict between the adjustment directions of elongation deviation and plate shape deviation, introducing a predefined priority rule or weighted optimization strategy to determine the comprehensive adjustment amount, wherein, when the elongation is close to the upper limit of the target elongation and there are obvious defects in the plate shape, plate shape adjustment is given priority and the elongation is allowed to increase moderately within the target range; when the elongation is close to the lower limit of the target elongation and the plate shape defect is slight, elongation stability is given priority.

6. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, In the coupling relationship model, the total elongation of the strip is composed of the elastic and plastic elongation components under the action of tension alone, the elongation component generated by the bending action of the bending roll group and the straightening roll group, and the cross-coupled elongation component under the combined action of tension and bending. The main effect coefficients and cross-coupling coefficients in the coupling relationship model are determined by offline experiments or prior production data calibration, and are adaptively adjusted based on the benchmark correction of equipment specifications, the nonlinear correction of material properties, and the thickness correction of specifications.

7. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, The strip shape detection device is used to detect the incoming strip shape data and the actual strip shape data; the tension detection device is used to detect the strip tension value in real time; the elongation detection device is used to detect the strip inlet and outlet speeds to calculate the actual elongation. The central controller is connected to the inlet tension roller group, the outlet tension roller group, the bending roller group, the straightening roller group, and each detection device.

8. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, The first preset threshold is dynamically determined based on the strip material characteristics and the target elongation setting value; the second preset threshold is determined based on the finished product shape quality grade requirements and strip thickness; at the same time, a control stability constraint is introduced, and when the tension fluctuation variance exceeds the preset range, the threshold is automatically amplified to avoid frequent operation of the actuator causing system oscillation.

9. The method for coordinated control of elongation and plate shape in a leveling and straightening machine according to claim 1, characterized in that, The central controller records the incoming material parameters, target control parameters, actual operating data, and product quality results for each straightening task and stores them in the process knowledge base. When processing similar incoming materials later, the central controller performs a similar case search based on historical successful cases in the process knowledge base to obtain an initial match of the target control parameters, thereby shortening the convergence time of coordinated control.

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