A dynamic self-adaptive control method for the level of a four-high reversing rolling mill

Abstract

The present application relates to the technical field of metallurgical rolling, and particularly relates to a kind of four-roll reversible mill's rolling line elevation dynamic self-adaptive control method.The fixed rolling line elevation control mode cannot adapt to the change of working condition in real time in multi-pass, large reduction rolling, there are process quality and equipment safety hidden danger, and the adjustment mode is rigid and inefficient.The present application includes: for the current rolling pass, according to the rolling pass type and real-time pass reduction, automatically calculate the HGC additional compensation amount to generate the rolling line elevation target instruction value of the current pass;The system further cooperates with the safety check of target instruction value, including: (a) logical safety check: compare the target instruction value with the preset rolling line elevation safety working interval, and generate logical allowed execution value accordingly; (b) hardware safety check: according to the real-time acquisition of HGC hydraulic cylinder stroke limit position, the target instruction value is checked.The dynamic self-adaptive and double safety cooperative control of rolling line elevation are realized.

Description

Technical Field

[0001] This invention relates to the field of metallurgical rolling technology, and in particular to a dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill. Background Technology

[0002] Four-high reversible rolling mills are widely used in the rolling production of medium and heavy plates, strips, and other metal materials due to their high rolling precision and strong process adaptability. The rolling line elevation is a core process parameter in the rolling process. It is defined as the relative height between the centerline of the workpiece and the reference plane of the mill stand, and directly affects the workpiece bite stability, the stress balance of the roll system, the thickness control accuracy, and the safety of equipment operation.

[0003] Currently, the industry commonly uses hydraulic gap control (HGC) systems to control the rolling line elevation, with fixed elevation control being the mainstream control mode. Specifically, before rolling, the HGC system performs a zero-point adjustment (zero-adjustment) operation to determine a fixed initial gap position. Throughout the subsequent rolling cycle (including multiple reversible passes), the rolling line elevation remains unchanged based on this fixed position, without adjustment based on changes in passes or rolling conditions.

[0004] However, in actual production processes, especially in the rolling of medium and heavy plates with multiple passes and large reductions, this fixed elevation control mode has gradually revealed serious technical defects, making it difficult to meet the production requirements of high quality, high efficiency, and high stability. Specifically, this is manifested in the following three aspects: Unable to dynamically adapt to varying rolling conditions: The reduction amounts differ significantly between different rolling passes, typically with a smaller reduction in the first pass and a gradually increasing reduction to a peak value in intermediate passes. Fixed elevations cannot be adjusted based on real-time changes in reduction amounts. In passes with large reduction amounts, the immense deformation resistance of the rolled piece easily triggers an "unloading" phenomenon in the roll system, leading to unexpected displacement and vibration between the work rolls and support rolls. This results in uneven wear on the roll surface, shortened bearing life, and affects the thickness accuracy of the rolled piece.

[0005] There are clear risks to process quality and equipment safety: When the reduction in a certain pass is too large, the fixed rolling line elevation may cause the lower work roll and support roll to disengage, leading to serious equipment impact failure. Conversely, if the initially set elevation value is too high, it is easy to induce "roll sitting" (the rolled piece deviating from the rolling center line and falling onto the roll) and roll surface slippage during the rolling process. This not only leads to surface quality defects or even scrapping of the rolled piece, but also disrupts the rolling continuity and seriously affects production efficiency.

[0006] Existing adjustment methods are rigid and inefficient: To address some issues related to fixed elevations, existing technologies have employed static solutions such as mechanically adjusting elevations by replacing stand shims, or one-time preset adaptation solutions for specific billet specifications. These solutions cannot respond to changes in operating conditions in real time during rolling, have long adjustment cycles, lack flexibility, and rely on manual experience, failing to achieve automated and intelligent dynamic control.

[0007] In summary, the existing fixed rolling line elevation control method based on the HGC system can no longer meet the stringent requirements of process adaptability, operational stability and equipment safety of four-high reversible rolling mills under multi-pass, variable-pressure, and high-load rolling conditions. Summary of the Invention

[0008] The purpose of this invention is to provide a dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill, which solves the problems of the fixed rolling line elevation control mode being unable to adapt to changes in working conditions in real time during multi-pass, large-reduction rolling, posing potential risks to process quality and equipment safety, and having a rigid and inefficient adjustment method.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill, comprising the following steps: S1 Rolling Line Elevation Target Instruction Generation: For the current rolling pass, based on the rolling pass type and real-time pass reduction, the HGC additional compensation amount is automatically calculated, and the rolling line elevation target instruction value for the current pass is generated based on the HGC additional compensation amount. S2 Dual Safety Cooperative Control: The system performs cooperative safety verification on the target command value of the rolling line elevation. The cooperative safety verification includes: (a) Logical safety verification: The target instruction value of the rolling line elevation is compared with the preset safe working range of the rolling line elevation, and a logical execution value is generated accordingly; If the target instruction value for the rolling line elevation is within the safe working range, then the logical execution value is equal to the target instruction value for the rolling line elevation; if the target instruction value for the rolling line elevation exceeds the safe working range, then the logical execution value is the corresponding boundary value of the safe working range. (b) Hardware security verification: The target command value of the rolling line elevation is verified based on the real-time collected HGC hydraulic cylinder stroke limit position; If the result of the hardware security verification indicates that the rolling line elevation target instruction value exceeds the hardware travel limit, the system performs a protection action; if it does not exceed the limit, the system drives HGC to execute the logically allowed execution value.

[0010] To improve operational flexibility and accommodate human experience, the following steps are included before step S1: S0 compensation preset: Receives manual compensation amount input by the operator through the human-machine interface before the start of rolling or during the pass interval; In step S1, the target instruction value for the rolling line elevation is generated based on the HGC additional compensation amount and the manual compensation amount.

[0011] In order to achieve precise adaptation to different rolling conditions, in step S1, When the current rolling pass is the first pass or the current pass reduction is 50mm to 55mm, the HGC additional compensation is 5mm; When the current pass reduction is greater than 55mm, the HGC additional compensation is 7mm.

[0012] To ensure the accuracy and reliability of the target command generation, in step S1, the generation benchmark for the target command value of the rolling line elevation is: after the HGC system is zero-adjusted, based on the target thickness of the workpiece, material characteristics and initial rolling speed parameters, the position of the HGC hydraulic cylinder corresponding to the initial rolling line elevation calculated by the rolling mill process model, with a zero-adjustment error ≤ 0.02mm.

[0013] To prevent misoperation and ensure adjustment accuracy, in step S2, the manual adjustment range of the manual compensation amount is limited to ±10mm, with an adjustment accuracy of 0.1mm.

[0014] In order to obtain high-precision real-time reduction data, in step S1, the real-time reduction per pass is calculated in real time by the thickness detection module at 500mm before the workpiece enters the roll and 500mm after it leaves the roll, with a detection accuracy of ≤0.1mm.

[0015] To constrain the process safety range, the safe working range of the rolling line elevation is defined as the range offset upwards by 10mm to 30mm from the center line of the stand rolls.

[0016] To clarify the specific response of the dual safety control mechanism after the introduction of manual intervention, if the target instruction value of the rolling line elevation generated by the superposition of the manual compensation amount and the HGC additional compensation amount exceeds the safe working range of the rolling line elevation but does not exceed the travel limit position, the logically allowed execution value generated by the system is the corresponding boundary value of the safe working range, and an early warning is triggered. If the target elevation command value of the rolling line exceeds the travel limit position, the system triggers the protection action.

[0017] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: This invention automatically calculates and applies corresponding additional compensation based on specific pass parameters and reduction variations, ensuring the rolling line elevation matches the current operating conditions. This counteracts the unloading effect of the roll system during high-reduction rolling, preventing process failures such as roll sitting and slippage caused by improper elevation, and improving the workpiece bite success rate. Furthermore, this method upgrades the control logic of the existing HGC system without requiring any modifications to the main mechanical structure or hydraulic actuators of the mill. The modification cycle for a single mill is short, and it is compatible with various four-high reversible mills. After application, it can effectively reduce the scrap rate, decrease unplanned downtime, and improve production efficiency.

[0018] By constructing a dual-collaborative safety protection system combining logic and hardware, the safe operation of the equipment is ensured. Combining process safety range restrictions with hardware limits forms a dual safety locking mechanism. This system can prevent risks caused by improper process parameter settings and prevent equipment damage due to exceeding limits, significantly extending the equipment's service life.

[0019] The system, with automatic dynamic compensation at its core, reduces the workload of operators. At the same time, it also provides an interface for manual fine-tuning during track intervals, combining the efficiency of automated control with the flexibility of human experience, enabling rapid response to various on-site operating conditions. Attached Figure Description

[0020] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a flowchart illustrating the dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill provided by the present invention. Figure 2 This is a flowchart illustrating the steps of the dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill provided by the present invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Figure 1This is a flowchart illustrating the dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill provided by the present invention. Addressing the problems of rigid elevation control and insufficient safety redundancy in existing rolling mills under complex operating conditions, this method proposes an intelligent control system based on current operating condition identification and multiple verifications. Through the synergistic effect of logic protection and hardware protection, it achieves real-time accurate adaptation of the rolling line elevation and safe and reliable operation.

[0024] Specifically, this process includes the following steps, see [link to relevant documentation]. Figure 2 : S1 Rolling Line Elevation Target Instruction Generation: For the current rolling pass, based on the rolling pass type and real-time pass reduction, automatically calculate the HGC additional compensation amount, and generate the rolling line elevation target instruction value for the current pass based on the HGC additional compensation amount.

[0025] The specific compensation rules are as follows: When the current rolling pass is the first pass or the current pass reduction is 50mm to 55mm, the HGC additional compensation is 5mm. When the current pass reduction is greater than 55mm, the HGC additional compensation is 7mm.

[0026] The real-time reduction per pass is calculated in real time by the thickness detection module, which collects thickness data at 500mm before the workpiece enters the roll and at 500mm after it leaves the roll. The detection accuracy is ≤0.1mm to ensure the accuracy and reliability of the working condition identification data.

[0027] The generation of the rolling line elevation target command value starts from the reference position after the HGC system completes zero adjustment. This reference position is calculated by the rolling mill process model based on parameters such as the target thickness of the workpiece, material properties, and initial rolling speed. The zero adjustment process ensures that the roll system fits tightly and the zero adjustment error is no more than 0.02mm, providing an accurate initial reference for dynamic adjustment.

[0028] S2 Dual Safety Cooperative Control: The system performs cooperative safety verification on the above-mentioned rolling line elevation target command value. The cooperative safety verification includes: (a) Logical safety verification: The system compares the target value of the rolling line elevation with the preset safe working range of the rolling line elevation. This safe working range is set according to the equipment structural parameters and process practice, and is within the range of 10mm to 30mm upward offset from the center line of the mill rolls. If the target instruction value is within this range, it will be directly used as the logically allowed execution value. If the target instruction value exceeds the range, the system will automatically correct it to the corresponding boundary value of the range and output it as the logically allowed execution value, while triggering a process warning signal to alert the operator.

[0029] (b) Hardware security verification: The system verifies the target command value of the rolling line elevation based on the real-time collected HGC hydraulic cylinder stroke limit position; If the target instruction value exceeds the hardware travel limit, the system will immediately perform protective actions, including locking the HGC actuator, triggering an audible and visual alarm, and suspending the rolling process, thus eliminating the risk of equipment damage from the hardware level. If the target instruction value does not exceed the hardware travel limit, the system will drive the HGC actuator to execute the logic allowed execution value output by the aforementioned logic safety check, and complete the final adjustment of the rolling line elevation.

[0030] Furthermore, to enhance the system's flexibility in handling special operating conditions and to accommodate manual operating experience, a compensation preset step S0 can be added before step S1. This step allows operators to input a manual compensation amount via the human-machine interface before rolling begins or during pass intervals. The adjustment range of this manual compensation amount is limited to ±10mm, with an adjustment accuracy of 0.1mm, providing the possibility for fine-tuning the process while ensuring safety.

[0031] In this case, the rolling line elevation target instruction value in step S1 will be generated based on the superposition of HGC additional compensation and manual compensation.

[0032] If the target instruction value of the rolling line elevation generated by the superposition of the manual compensation amount and the HGC additional compensation amount exceeds the safe working range of the rolling line elevation but does not exceed the stroke limit position, the logically allowed execution value generated by the system is the corresponding boundary value of the safe working range, and an early warning is triggered. If the target elevation command value of the rolling line exceeds the travel limit position, the system will trigger a protection action.

[0033] The present invention will be further illustrated below through specific embodiments: Example

[0034] This embodiment uses a 3800mm four-roll reversible medium-thick plate rolling mill of a steel company as the application object.

[0035] I. System Configuration and Initial Parameters In this embodiment, the core parameters of the rolling mill and the modified system configuration are as follows: Mill specifications: 3800mm four-high reversible mill, with stand roll diameter of 800mm.

[0036] HGC system: maximum stroke of hydraulic cylinder 500mm, maximum working pressure 31.5MPa.

[0037] Detection unit: Thickness measurement: A laser thickness gauge is used, installed at a distance of 500mm from the center line of the roll on both the inlet and outlet sides of the rolling mill, with a measurement accuracy of ±0.01mm.

[0038] Control unit: Core controller: The main PLC system of the rolling mill is responsible for pass counting, process model calculation and logic scheduling.

[0039] Dynamic adjustment module: Integrated into the HGC control program as a software function block to realize compensation calculation, safety verification and instruction correction.

[0040] Human-Machine Interface: Industrial touch screen for parameter display, alarms, and providing an optional manual compensation input interface (adjustment accuracy 0.1mm).

[0041] Process parameters: Raw material: 1.2311 die steel, initial thickness 455mm, target finished thickness 112mm, rolling width 2100mm.

[0042] Rolling procedure: There are a total of 8 loaded rolling passes, including 1 empty pass.

[0043] Initial rolling speed: 1.5 m / s.

[0044] Safe working range setting: Based on equipment structure and practical experience, it is set to offset the center line of the frame roller upward by 10mm to 30mm.

[0045] Hardware stroke limits: The contact position (lower limit) and maximum extension position (upper limit) of the HGC hydraulic cylinder are automatically calibrated by the system.

[0046] II. Implementation steps of this example S1 System Initialization and Baseline Settings After the mill starts, the HGC system zero-adjustment operation is performed first, driving the lower work roll and support roll to fit tightly together and establish a precise mechanical zero point. After the zero-adjustment is completed, based on the billet parameters and process requirements, the initial rolling parameters are calculated using the mill's built-in process model to determine the reference rolling position, whose corresponding rolling line elevation is 20mm upward offset from the mill stand roll centerline. At this point, the dynamic adjustment module is activated, and the system initial compensation is 0mm.

[0047] S2 First Pass Rolling and Automatic Compensation Upon entering the first rolling pass, the pass counting module identifies this as the first pass. The dynamic adjustment module automatically triggers a 5mm additional compensation command based on preset rules. The HGC system receives the command and adjusts the rolling position to the reference position +5mm, corresponding to an actual rolling line elevation of 25mm. The thickness detection module collects real-time data on the inlet thickness of 455mm and the outlet thickness of 397mm, calculating a reduction of 58mm for this pass. Although the reduction is greater than 55mm, the compensation remains unchanged at 5mm due to the priority given to the first pass rule. The workpiece bites smoothly, with no abnormal vibration or slippage in the roll system.

[0048] S3 Subsequent Track Dynamic Adaptive and Compensation Switching S31, second pass: Pass count update. The thickness detection module collects the inlet thickness of 397mm, and according to the specification, the outlet thickness is set to 340mm, calculating the reduction as 57mm (>55mm). The dynamic adjustment module automatically switches to adjust the additional compensation to 7mm. The HGC execution position is updated to the reference position +7mm, corresponding to a rolling line elevation of 27mm, to adapt to the large reduction condition. During the rolling process, the roll system runs smoothly, and unloading vibration is effectively suppressed.

[0049] For passes S32, the reduction amounts for the third to fifth passes are 48mm, 35mm, and 20mm respectively, all less than 50mm. The dynamic adjustment module automatically maintains a 5mm compensation amount, keeping the rolling line elevation stable at 25mm. The system automatically switches the compensation mode based on changes in the reduction amount, achieving real-time adaptation of the rolling line elevation to the operating conditions.

[0050] S4 optional manual intervention practice During the fourth rolling pass, the operator observed a slight slippage trend at the edge of the rolled piece via the human-machine interface (HMI). To make immediate adjustments, the operator manually input a +2.5mm fine-tuning compensation (within the allowable ±10mm range) through the input interface. The system superimposed this manual compensation on the 5mm compensation automatically calculated for the current pass, generating a new target elevation command value for the rolling line. After logical safety verification, this command value (corresponding to an elevation of 27.5mm) was within the safe operating range of 10-30mm, and the system generated the logically permissible execution value without warning. After hardware safety verification also passed, the HGC immediately executed the adjustment, quickly eliminating the slippage trend at the edge of the rolled piece, and the rolling continuity remained unaffected.

[0051] S5 Dual Security Control Mechanism Verification S51 Logic Safety Limit Test: In a stable pass, an attempt was made to manually input +5mm, which, when superimposed on the current automatic compensation of 7mm, resulted in a target instruction value corresponding to an elevation of 32mm. The system's logic safety module immediately detected that this value exceeded the 30mm upper limit, automatically corrected it to 30mm, and displayed a yellow warning message on the HMI stating "Rolling line elevation is approaching the upper limit." The HGC actually executed the corrected 30mm elevation, and rolling continued. The operator then manually reset the input to +2mm, and the warning was lifted.

[0052] S52 Hardware Safety Limit Test: Simulating extreme misoperation, an attempt was made to input a +12mm manual compensation amount, which, when combined with a 7mm automatic compensation amount, resulted in a target command value corresponding to an elevation of 39mm. The system logic module initially corrected this to 30mm. However, during the hardware safety verification phase, the system detected that the original target command value (39mm) exceeded the maximum extension limit of the HGC hydraulic cylinder (38mm). The hardware safety module immediately triggered a protection operation, forcibly locking the HGC hydraulic cylinder at the 38mm limit position, triggering a red audible and visual alarm, and suspending the rolling process. The alarm was deactivated and rolling resumed only after the operator corrected the manual compensation amount to a safe value and confirmed it.

[0053] S6 Full-Process Control Performance and Data Comparison Throughout the entire rolling process (8 loaded passes), the system ensures that the rolling line elevation remains within a safe and reasonable range of 10-30mm through the synergistic effect of the dynamic adjustment module and the dual safety control mechanism.

[0054] Quality indicators: The final product thickness is 112mm, and the thickness accuracy error is ±0.04mm, which is better than the process requirements.

[0055] Stability indicators: No roller slippage, no roller system disengagement failures throughout the entire process. Roller system vibration amplitude was monitored online, with a peak value ≤0.03mm, significantly better than the level before the modification. Based on three consecutive months of production statistics, unplanned downtime due to elevation issues was zero, equipment maintenance costs decreased by 32%, and production efficiency increased by 21.5%.

[0056] In summary, this embodiment fully demonstrates that the dynamic adaptive control method for the rolling line elevation of the four-roll reversible rolling mill provided by this invention can achieve real-time perception, adaptive compensation, and multiple safety protections of the rolling conditions through software upgrades without modifying the main structure of the rolling mill. This method significantly improves the stability of the rolling process, product quality, and equipment safety, and possesses good operational flexibility and engineering application value, making it particularly suitable for production scenarios involving multi-pass, large-reduction rolling of medium-thick plates and high-strength steel.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill, based on an HGC hydraulic roll gap control system, characterized in that... Includes the following steps: S1 Rolling Line Elevation Target Instruction Generation: For the current rolling pass, based on the rolling pass type and real-time pass reduction, the HGC additional compensation amount is automatically calculated, and the rolling line elevation target instruction value for the current pass is generated based on the HGC additional compensation amount. S2 Dual Safety Cooperative Control: The system performs cooperative safety verification on the target command value of the rolling line elevation. The cooperative safety verification includes: (a) Logical safety verification: The target instruction value of the rolling line elevation is compared with the preset safe working range of the rolling line elevation, and a logical execution value is generated accordingly; If the target instruction value for the rolling line elevation is within the safe working range, then the logical execution value is equal to the target instruction value for the rolling line elevation; if the target instruction value for the rolling line elevation exceeds the safe working range, then the logical execution value is the corresponding boundary value of the safe working range. (b) Hardware security verification: The target command value of the rolling line elevation is verified based on the real-time collected HGC hydraulic cylinder stroke limit position; If the result of the hardware security verification indicates that the rolling line elevation target instruction value exceeds the hardware travel limit, the system performs a protection action; if it does not exceed the limit, the system drives HGC to execute the logically allowed execution value.

2. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, Before step S1, the following steps are also included: S0 compensation preset: Receives manual compensation amount input by the operator through the human-machine interface before the start of rolling or during the pass interval; In step S1, the target instruction value for the rolling line elevation is generated based on the HGC additional compensation amount and the manual compensation amount.

3. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, In step S1, When the current rolling pass is the first pass or the current pass reduction is 50mm to 55mm, the HGC additional compensation is 5mm; When the current pass reduction is greater than 55mm, the HGC additional compensation is 7mm.

4. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, In step S1, the benchmark for generating the target command value of the rolling line elevation is: after the HGC system is zero-adjusted, based on the target thickness of the workpiece, material properties and initial rolling speed parameters, the position of the HGC hydraulic cylinder corresponding to the initial rolling line elevation is calculated by the rolling mill process model, and the zero-adjustment error is ≤0.02mm.

5. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 2, characterized in that, In step S2, the manual adjustment range of the manual compensation amount is limited to ±10mm, with an adjustment accuracy of 0.1mm.

6. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, In step S1, the real-time reduction per pass is calculated in real time by the thickness detection module by collecting thickness data at 500mm before the workpiece enters the roll and at 500mm after it leaves the roll, with a detection accuracy of ≤0.1mm.

7. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, The safe working range for the rolling line elevation is defined as the range offset upwards by 10mm to 30mm from the center line of the mill stand rolls.

8. The dynamic adaptive control method for the rolling line elevation of a four-roll reversible rolling mill according to claim 1, characterized in that, If the target command value of the rolling line elevation generated by the superposition of the manual compensation amount and the HGC additional compensation amount exceeds the safe working range of the rolling line elevation but does not exceed the travel limit position, then the logically allowed execution value generated by the system is the corresponding boundary value of the safe working range, and an early warning is triggered. If the target elevation command value of the rolling line exceeds the travel limit position, the system triggers the protection action.

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