A plate convexity control system
By introducing bending roll force feedback control and work roll adjustment modules into the hot strip mill wide strip production line, combined with PI control and model self-learning, the shape quality problem of wide thin strip steel plates was solved, and high-standard crown control and product quality improvement were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING ABLYY TECH DEV CO LTD
- Filing Date
- 2023-05-16
- Publication Date
- 2026-05-26
AI Technical Summary
The lack of roll grinding machines and high-level operating conditions in the hot strip mill medium-width production line makes it difficult to achieve high standards in the quality of wide thin strip steel products, especially in terms of plate shape quality issues such as double-sided waves, single-sided waves, local high points, and wedge shapes.
By employing a bending roll force feedback control module and a work roll adjustment module, combined with a PI controller and a model self-learning module, the automatic control of the finishing mill is achieved by calculating the crown deviation and adjusting the bending roll force, thereby optimizing the strip shape quality.
Effectively control the average crowning index and target standard deviation of wide thin strip steel to improve product quality and eliminate strip shape defects.
Smart Images
Figure CN116493418B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of automatic plate shape control technology, specifically relating to a plate shape convexity control system. Background Technology
[0002] Hot strip mill wide strip production lines typically do not have the advantages of wide strip production lines, such as the ability of roll grinding machines to grind special roll curves and the high level of operator and maintenance skills. However, as downstream users in the market have increasingly higher requirements for the product quality of wide and thin strip steel, especially for the production of wide and thin specifications, the requirements for plate shape quality are also increasing. It is urgent to eliminate plate shape problems such as double-sided waves, single-sided waves, local high points, wedges, and 1 / 4 waves. Summary of the Invention
[0003] To address the above technical problems, the technical solution proposed in this invention includes a bending roll force feedback control module and a work roll adjustment module for realizing basic automated level control functions;
[0004] The bending roller force feedback control module is configured as follows:
[0005] Calculate the crown deviation e at the exit of each upstream stand of the finishing mill. i The convexity deviation at the exit of each frame is input into the PI controller, which outputs a convexity feedback adjustment signal to the work roll adjustment module for sequentially adjusting the bending roll force of the upstream frame; wherein, the PI controller calculates the convexity feedback adjustment signal according to the PI control model configured according to Equation I:
[0006]
[0007] The bending roll force is adjusted based on the convexity feedback of the i-th upstream frame during the k-th control cycle. Adjustment coefficients for the convexity feedback control model; For the convexity feedback proportional coefficient of the i-th upstream rack; K represents the convexity feedback integral coefficient of the i-th upstream rack; c e is the coefficient of influence of bending roller force on crown. i (j) represents the convexity deviation of the upstream rack outlet in the j-th control cycle; i is a natural number;
[0008] The work roll adjustment module is configured to adjust the bending roll force of each upstream stand of the finishing mill according to the convexity feedback adjustment signal.
[0009] This invention is used in a hot strip mill wide strip production line, and can achieve the effect of controlling the average crown and the target standard deviation of crown of the wide strip steel produced in the hot strip mill wide strip mill production line to meet the parameters specified in Table 1.
[0010] Table 1 Product Specifications for Wide Thin Strip Steel
[0011] Attached Figure Description
[0012] Figure 1 : Control principle diagram of the plate convexity control system in some implementations;
[0013] Figure 2 The execution steps of the model self-learning module in some implementation methods. Detailed Implementation
[0014] First, the relevant technical background in this field is introduced. Hot-rolled strip steel production lines include stages such as raw material preparation, heating, rough rolling, finish rolling, and coiling. Finishing processes may also be included. In the rough rolling process, the task of the roughing mill is to roll the slab into strip that meets the requirements of the finish mill. The last stand of the roughing mill is typically equipped with thickness, width, and temperature measuring devices to obtain the necessary data for automatic control. The length of the intermediate roller table between the roughing and finish mills is set according to the strip size and operational requirements.
[0015] The finishing rolling section typically consists of a hot continuous rolling mill unit composed of multiple finishing mills. With increasing production demands, and to adapt to high-speed rolling, the finishing rolling section must be equipped with a high-speed, accurate pressure execution system and a corresponding automated control system.
[0016] The shape control of hot strip mill production lines mainly includes process and equipment aspects. Process control strategies include: rationally arranging the rolling schedule for different product specifications; rationally allocating rolling combinations; adjusting roll temperature; tension control; and asynchronous rolling. Equipment control strategies include: original crown roll method, hydraulic roll bending method, roll crown adjustment method (such as VC mills, DSR mills, and NIPCO mills), roll deformation self-compensation method, stepped support roll method, zigzag roll method (such as HC mills, CVC mills, and UPC mills), online grinding roll method (ORG), and roll crossing method (PC mill). Shape control strategies are also crucial for ensuring strip quality, and currently mainly include three aspects: flexible roll gap control strategy, rigid roll gap control strategy, and uniform wear control strategy.
[0017] The hot strip steel production line involved in this invention includes Figure 1The diagram shows the roughing mill and finishing mill. The roughing mill's function is to descaling, width-fixing, and rolling with horizontal and vertical rollers onto heated slabs, producing finishing slabs of different specifications with thicknesses of 30-60 mm and varying widths, while maintaining the required temperature for the finishing slabs. The finishing mill is the core equipment on a hot-rolled strip continuous rolling line, primarily responsible for reducing the strip's thickness and controlling its shape. Finishing is a crucial process that determines product quality. The finishing mill is equipped with a bending roll system consisting of multiple stands.
[0018] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the present invention.
[0019] The principle of some implementations of the plate convexity control system is as follows: Figure 1 As shown, it includes a bending roll force feedback control module and a work roll adjustment module for implementing basic automation level control functions, and a plate shape pre-setting model and a model self-learning module for implementing process automation level control functions.
[0020] The bending roller force feedback control module is configured as follows:
[0021] Calculate the crown deviation e at the exit of each upstream stand of the finishing mill. i The convexity deviation at the exit of each frame is input into the PI controller, which outputs a convexity feedback adjustment signal to the work roll adjustment module for sequentially adjusting the bending roll force of the upstream frame; wherein, the PI controller calculates the convexity feedback adjustment signal according to the PI control model configured according to Equation I:
[0022]
[0023] The bending roll force is adjusted based on the convexity feedback of the i-th upstream frame during the k-th control cycle. Adjustment coefficients for the convexity feedback control model; For the convexity feedback proportional coefficient of the i-th upstream rack; K represents the convexity feedback integral coefficient of the i-th upstream rack; c e is the coefficient of influence of bending roller force on crown. i (j) represents the convexity deviation of the upstream rack outlet in the j-th control cycle; i is a natural number;
[0024] The model self-learning module is configured to calculate the plate shape deviation by self-learning the measured plate shape value and the target plate shape value collected from the last stand exit of the finishing mill, and to correct various parameters of the plate shape preset model according to the plate shape deviation;
[0025] The work roller adjustment module is configured as follows:
[0026] The bending roll force of each upstream stand of the finishing mill can be adjusted according to the convexity feedback adjustment signal; the bending roll force of each upstream stand of the finishing mill can also be adjusted according to the plate shape deviation.
[0027] The steps for calculating the crown deviation ei at the exit of each upstream stand of the finishing mill include, based on the crown deviation e at the exit of the last stand of the finishing mill. n Calculate the crown deviation e at the exit of each upstream stand of the finishing mill according to Formula II. i :
[0028] e i (j)=e n (j)h i / h n Formula II
[0029] Among them, e i (j) represents the convexity deviation of the i-th rack outlet during the j-th control cycle; e n (j) represents the convexity deviation of the rack outlet at the end of the j-th control cycle; h i h is the strip exit thickness of the i-th frame; n The thickness at the exit of the last stand of the finishing mill unit is denoted as i; i and j are natural numbers.
[0030] In some more specific implementations, the model self-learning module calculates the shape deviation by self-learning the measured shape value and the target shape value collected from the last stand exit of the finishing mill, and corrects various parameters of the pre-set shape model according to the shape deviation; the work roll adjustment module adjusts the bending roll force of each upstream stand of the finishing mill according to the shape deviation.
[0031] In the above embodiments, the steps for correcting the parameters of the pre-set plate shape model based on the plate shape deviation are as follows: Figure 2 ,include:
[0032] S1 acquires the measured crown value collected from the exit of the last stand of the finishing mill;
[0033] S2 computer frame unit width rolling force;
[0034] S3 uses the measured convexity value to recalculate the parameters of the pre-set plate shape model, specifically including recalculating the roll convexity;
[0035] S4 uses the measured crowning value to back-calculate the roll crowning;
[0036] S5 calculates the effective proportional convexity of the input.
[0037] The process of calculating plate shape deviation through self-learning specifically includes the following steps:
[0038] Calculate the work roll fine-tuning value, which includes the bending roll force of each upstream frame;
[0039] Input the inversely calculated roll crown and the recalculated roll crown, and output the self-learning work roll crown error, the self-learning work roll crown fine-tuning value, and the self-learning work roll crown compensation value.
[0040] The self-learning module uses the exponential smoothing method to calculate the roll crown βn+1=βn+α(β*n-βn)).
[0041] Some implementations of the plate shape presetting model include a bending roll force setting function module, which is used to set and calculate the bending roll force of the work rolls for each stand of the finishing mill, provided that the rolling force has been set, the roll type of the work roll and the support roll has been determined, and the roll shifting setting has been completed.
[0042] Some implementation methods use measured crown values to recalculate various parameters of the pre-set plate shape model, specifically including: obtaining the influence coefficients under different working conditions offline based on the elastic deformation analysis model of the roll system using the finite element method and storing them in the process control computer; the influence coefficients under different working conditions are sent to the bending roll force feedback control module and the work roll adjustment module along with the pre-set plate shape value, model parameters, PID parameters, etc., along with the finishing mill setting calculation.
[0043] Some implementations also include a shape and thickness decoupling control module for implementing basic automation-level control functions; the shape and thickness decoupling control module uses the adjustment amount of the automatic gain control algorithm to send to the inner loop APC (automatic position control) and ASC (automatic shape control) to calculate the compensation amount, and the work roll adjustment module adjusts the bending roll force of the last two stands of the finishing mill according to the compensation amount.
[0044] In the production process, due to the short control cycle and fast response of the AGC hydraulic cylinder, AGC control prioritizes adjustment. During automatic thickness control, the rolling force changes in real time. When a large error in the secondary roll gap setting leads to a significant thickness deviation, the AGC adjustment is large, increasing the fluctuation range of the rolling force and causing fluctuations in crown and flatness. Therefore, it is necessary to quickly compensate for the fluctuations caused by AGC. Decoupling control of plate shape and thickness is mainly applied in the last two stands of the finishing mill.
[0045] The decoupled control of plate shape and thickness utilizes the adjustment amount calculated by AGC, which is simultaneously sent to the ASC for compensation calculation while being fed to the inner ring APC. This accelerates the adjustment speed, and the bending roller force varies according to the compensation amount. The calculation formula is as follows: The decoupled control of plate shape and thickness utilizes the adjustment Δ amount calculated by AGC, which is simultaneously sent to the ASC for compensation calculation while being fed to the inner ring APC. This accelerates the adjustment speed, and the bending roller force varies according to the compensation amount. The calculation is based on Equation III:
[0046]
[0047] Wherein, ΔBF: the corresponding adjustment amount of bending roll force after roll gap adjustment, t; ΔS: AGC adjustment amount, mm. When AGC increases (ΔS>0), the bending roll force should be small, and vice versa (ΔS<0), the bending roll force should be increased; MP: mill longitudinal stiffness coefficient, t / mm; Q: strip plasticity coefficient, t / mm; Bending roll force - rolling force feedforward control model coefficients; α: adjustment coefficient.
[0048] In some specific implementations, the system is activated after the crown gauge in the hot strip rolling production line is working normally and detects the strip passing through signal.
[0049] In some embodiments, the actual crown value of the strip measured by the crown meter is compared with the target crown value to determine the crown feedback control deviation. This deviation is then eliminated by adjusting the bending roll force of the upstream stand in the finishing mill. When the measured crown value is greater than the target crown value, the bending roll force of the upstream stand is increased; conversely, the bending roll force of the upstream stand is decreased. To ensure that the flatness is not affected during crown feedback adjustment, the bending roll force of the downstream stand is also adjusted accordingly. The crown feedback control uses an algorithm based on a digital PID controller, enabling crown feedback control across the entire strip mill and improving the crown accuracy along the entire strip length.
[0050] In some embodiments, the adjustment amount of the bending roller force of each frame needs to take into account the equipment's limiting capacity during the implementation of convexity feedback control. Preferably, both the control cycle and the cycle of the convexity detection signal of the convexity meter are 2 seconds.
[0051] In an automatic strip shape control system, to control the crown without affecting the straightness of the strip, it is essential to ensure that the proportional crown between stands is equal. During normal operation, the crown meter periodically detects the crown value of the strip at the finishing mill exit, thereby allowing the calculation of the deviation between the actual crown and the target crown value.
[0052] In some embodiments, the finishing mill has seven stands. Since thicknesses of 6-12mm and above 12mm fall within the rolling thickness range of F1-F3, a flared opening is provided at F1-F3 to allow for crown adjustment. The crown (relative crown) of the incoming strip can be corrected in the first three stands of the finishing mill without compromising the straightness of the strip. Based on the Shohet and Townsend discriminant formulas, the control strategy of the automatic strip shape control system is as follows: according to the strategy that the upstream stands mainly control the strip crown and the downstream stands control the straightness, crown feedback control is implemented in F2-F7 of the finishing mill. The crown feedback control of F2-F5 mainly adjusts the strip crown to the target proportional crown; while the crown feedback control of F6 and F7 mainly ensures that the straightness of the strip is not affected during crown feedback, under the principle of equal proportional crown.
[0053] It should be noted that the multiple functional modules in the above embodiments of the present invention can share the computing resources of the data processing device or the storage resources. The time-sharing multiplexing strategy often appears in the preferred embodiments.
[0054] The embodiments and functional operations of the subject matter described in this specification can be implemented in the following ways: digital electronic circuits, tangibly implemented computer software or firmware, computer hardware, including the structures disclosed in this specification and their equivalents, or combinations thereof. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, that is, one or more modules of computer program instructions encoded on one or more tangible non-transitory program carriers, for execution by a data processing device or to control the operation of the data processing device.
[0055] The term "data processing device" encompasses all kinds of devices, apparatuses, and machines used for processing data, including, for example, programmable processors, computers, or multiprocessor systems or multicomputer systems. Devices may include special-purpose logic circuitry, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits). In addition to hardware, devices may also include code that creates the execution environment for associated computer programs, such as processor firmware, protocol stacks, database management systems, operating systems, or combinations thereof.
[0056] Computer programs (which may also be referred to or described as programs, software, software applications, modules, software modules, scripts, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and can be expanded in any form, including as standalone programs or as modules, components, subroutines, or other units suitable for use in a computing environment. A computer program may, but must not, correspond to a file in a file system. A program may be stored as a portion of a file containing other programs or data, for example, as one or more scripts in a markup language document; in a single file dedicated to the related program; or in multiple co-files, for example, a file storing one or more modules, subroutines, or code portions. A computer program can be expanded to execute on one or more computers located in one place or distributed across multiple locations and interconnected via a communication network.
[0057] The processing and logic flows described in this specification can be executed by one or more programmable computers, which execute one or more computer programs by processing input data and generating output to run functions. The processing and logic flows can also be executed by special-purpose logic circuitry, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits), and the device can also be implemented as special-purpose logic circuitry.
[0058] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather as descriptions of features that can embody specific embodiments of a particular invention. Specific features described in this specification within the context of an independent embodiment may also be implemented in combination with a single embodiment. Conversely, various features described within the context of a single embodiment may also be implemented independently in multiple embodiments, or in any suitable sub-combination. Furthermore, while features may be described for combination and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and the claimed combination may be redirected to a sub-combination or a variation thereof.
[0059] Specific implementations of the subject matter have been described. Other implementations are within the scope of the following claims. For example, the activities described in the claims can be performed in a different order and still achieve the desired result. As an example, the processes described in the drawings do not necessarily require a specific order or sequence to be shown in order to achieve the desired result. In certain implementations, multitasking and parallel processing may be advantageous.
Claims
1. A plate crown control system for sequentially adjusting the bending roll force of each upstream stand of the finishing mill in a hot continuous rolling production line, characterized in that, It includes a bending roll force feedback control module and a work roll adjustment module for implementing basic automation-level control functions; it also includes a plate shape pre-setting model and a model self-learning module for implementing process automation-level control functions; The bending roller force feedback control module is configured as follows: Calculate the crown deviation e at the exit of each upstream stand of the finishing mill. i The convexity deviation at the exit of each frame is input into the proportional-integral controller, which outputs the convexity feedback adjustment amount to the work roll adjustment module for sequentially adjusting the bending roll force of the upstream frame; wherein, the proportional-integral controller calculates the convexity feedback adjustment amount according to the proportional-integral control model of Equation I: Mode This refers to the convexity feedback adjustment amount for the i-th upstream rack in the k-th control cycle; Adjustment coefficients for the convexity feedback control model; For the convexity feedback proportional coefficient of the i-th upstream rack; For the convexity feedback integral coefficient of the i-th upstream rack; e is the coefficient of influence of bending roller force on crown. i (j) represents the convexity deviation of the upstream frame outlet in the j-th control cycle; i is a natural number, and the bending roller force feedback control module is defined according to formula... Calculate the crown deviation e at the exit of each upstream stand of the finishing mill. i : Formula II Among them, e i (j) represents the convexity deviation of the i-th rack outlet during the j-th control cycle; e n (j) represents the convexity deviation of the rack outlet at the end of the j-th control cycle; h i h is the strip exit thickness of the i-th frame; n The thickness at the exit of the last stand of the finishing mill unit is denoted as i; i and j are natural numbers.
2. The plate convexity control system as described in claim 1, characterized in that, The pre-set shape model is used to compensate for thermal crown and wear crown. The model self-learning module calculates the shape deviation by comparing the measured shape value collected from the last stand exit of the finishing mill with the target shape value, and corrects multiple parameters, including the bending roll force feedforward influence coefficient, the bending roll force influence coefficient on crown, and the bending roll force influence coefficient on straightness, based on the shape deviation. The work roll adjustment module adjusts the bending roll force of each upstream stand of the finishing mill according to the shape deviation.
3. The plate convexity control system as described in claim 2, characterized in that, The plate shape preset model includes a bending roll force setting model and a shifting roll setting model; The steps for correcting the parameters of the pre-set plate shape model based on the plate shape deviation include: Obtain the measured crown value collected from the exit of the last stand of the finishing mill; Rolling force per unit width of the computer frame; The parameters of the pre-set plate shape model are recalculated using the measured convexity values, specifically including recalculating the roll convexity. The roll crown is calculated by back-calculating the actual crown value; Calculate the effective proportional convexity of the inlet.
4. The plate convexity control system as described in claim 2, characterized in that, Calculating plate shape deviation through self-learning includes the following steps: Calculate the work roll fine-tuning value, which includes the bending roll force of each upstream frame; Input the reverse calculated roll crown and the recalculated roll crown, and output the self-learning work roll crown error, the self-learning work roll crown fine-tuning value, and the self-learning work roll crown compensation value.
5. The plate convexity control system as described in claim 2, characterized in that, The plate shape pre-setting model includes a bending roll force setting function module, which is used to set and calculate the bending roll force of the work rolls on each stand of the finishing mill, provided that the rolling force has been set, the roll shape of the work roll and the support roll has been determined, and the roll shifting setting has been completed.
6. The plate convexity control system as described in claim 3, characterized in that, The specific steps for recalculating the parameters of the pre-set plate shape model using the measured crown value include: obtaining the influence coefficients under different working conditions through offline calculation using the finite element method based on the elastic deformation analysis model of the roll system, and storing them in the process control computer; the influence coefficients under different working conditions are sent to the bending roll force feedback control module and the work roll adjustment module along with the pre-set plate shape value, model parameters, and PID parameters, along with the finishing mill setting calculation.
7. The plate convexity control system as described in claim 3, characterized in that, It also includes a plate shape and thickness decoupling control module for implementing basic automation-level control functions; the plate shape and thickness decoupling control module uses the adjustment amount calculated by AGC to send to the inner ring APC and simultaneously to ASC to calculate the compensation amount, and the work roll adjustment module adjusts the bending roll force of the last two stands of the finishing mill according to the compensation amount.
8. The plate convexity control system as described in claim 1, characterized in that, The crown gauge on the hot strip rolling production line is activated after it is working normally and detects the strip passing through.
9. A method for controlling plate crown, wherein the method is used in a hot continuous rolling production line, characterized in that, The plate convexity control method includes the plate convexity control system as described in any one of claims 1-8.