Method for automatically rolling slab ingot through reversible medium plate four-high mill

Abstract

The invention relates to the technical field of metallurgical rolling, in particular to a method for automatically rolling slab ingots through a reversible medium plate four-high mill. The problems that due to the wedge-shaped structure of the slab ingot, the automation degree is low, the slab ingot depends on manual experience, material tracking is prone to failure, rolling is unstable, and the product quality is low are solved. Comprising the steps that geometric characteristic parameters of a target slab ingot are obtained, a three-dimensional wedge-shaped mathematical model of the slab ingot is constructed according to the geometric characteristic parameters, and a rolling schedule containing multi-pass rolling reduction is generated; an EXBXL rolling program is adopted, and at least two special flattening rolling passes are arranged in the initial rolling stage; then, in the two flattening rolling passes, whether the current rolling pass is effectively completed or not is judged based on material position signals collected by hot metal detectors on the inlet side and the outlet side of the rolling mill; and finally, the rolling mill is controlled to conduct constant-speed rolling at the constant linear speed, and the rolling acceleration is maintained to be 0 m / s < 2 >. According to the method, the production efficiency and the product consistency are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical rolling technology, and in particular to a method for automatically rolling flat ingots using a reversible four-roll mill for medium-thick plates. Background Technology

[0002] In the field of metallurgical rolling, flat ingots are key billets for the production of medium and heavy plates. Due to the inherent characteristics of continuous casting process, flat ingots generally have significant "wedge-shaped" structural defects after solidification. Specifically, along the length direction, there are dimensional differences in both thickness and width between the head (large head) and the tail (small head), that is, the whole is a double-wedge-shaped irregular body.

[0003] Currently, mainstream rolling processes face significant challenges in producing wedge-shaped flat ingots with uneven dimensions. The difference in size between the large and small ends causes drastic fluctuations in the rolling force feedback signal during the rolling process. This is especially true when the mill bites into the smaller end of the flat ingot, where the insufficient contact area between the rolls and the billet often results in the actual rolling force falling below the sensor's effective detection threshold, thus failing to generate a reliable status feedback signal. This leads to frequent failures in conventional automated rolling systems that rely on rolling force signals for pass validity assessment and material tracking, resulting in the loss of material position information and interruptions in the automated process.

[0004] Therefore, in actual production, the rolling of such wedge-shaped flat ingots heavily relies on manual intervention by operators. Operators must rely on their personal experience to observe, judge, and manually adjust the reduction, rolling speed, and rolling rhythm of each pass in real time. This production method has the following inherent drawbacks: Low production efficiency: Manual operation is slow and the adjustment of the number of passes is time-consuming, which cannot meet the needs of continuous and large-scale production.

[0005] Unstable rolling precision: Product quality relies too much on personal experience, and there are large differences in rolling results between different shifts and different operators. It is difficult to achieve stable and precise control over the dimensional tolerances of finished products (such as thickness and width).

[0006] Frequent product quality issues: Due to uneven dimensions, the billet is prone to "slipping" or "skewing" in the roll gap during the rolling process due to unbalanced forces, which seriously affects the flatness of the plate and may cause surface defects such as edge cracks and folds.

[0007] In summary, the existing technology lacks an effective method for stable, precise, and fully automated rolling of wedge-shaped flat ingots, which has become a key technological bottleneck restricting the improvement of automation level, product quality improvement, and production cost reduction of medium and heavy plate production lines. Summary of the Invention

[0008] The purpose of this invention is to provide a method for automatically rolling flat ingots using a reversible four-roll mill for medium and heavy plates. This method solves the problems of low automation, reliance on manual experience, easy failure of material tracking, interruption and instability of the rolling process, and difficulty in controlling product quality caused by the wedge-shaped (large and small ends) structure of the flat ingots.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates, comprising the following steps: S1: Obtain the geometric feature parameters of the target flat ingot, and based on the geometric feature parameters, construct a three-dimensional wedge mathematical model of the flat ingot in the rolling mill control system, automatically calculate and generate a rolling schedule containing multiple passes of reduction. S2: A rolling program based on the EXBXL strategy is adopted, and at least two dedicated leveling rolling passes are set in the initial rolling stage of the program to preliminarily correct and homogenize the wedge size deviation of the flat ingot in the thickness and width directions. S3: During the execution of the at least two leveling rolling passes, based on the material position signals collected by the hot metal detectors arranged on the inlet and outlet sides of the mill, it is determined whether the current rolling pass has been effectively completed. S4: During the execution of the at least two leveling rolling passes, the rolling mill is controlled to perform uniform rolling at a constant linear velocity, and the rolling acceleration is maintained at 0 m / s². 2 This is to stabilize the friction between the rolls and the flat ingot, and to prevent slippage and skew.

[0010] To ensure precise matching between the rolling schedule and the specific billet, the geometric feature parameters include at least the thickness of the large end (H1), the thickness of the small end (H2), the width of the large end (W1), the width of the small end (W2), and the length of the flat billet (L).

[0011] To ensure the process adaptability of the rolling schedule, in step S1, during the automatic calculation and generation of the rolling schedule, the reduction amount is also calculated in combination with the target finished product size and process parameters. The process parameters include at least the material type of the flat ingot and the initial rolling temperature.

[0012] In order to effectively eliminate the initial shape deviation in the leveling passes, the total reduction of the at least two leveling rolling passes is determined based on the initial wedge deviation values ​​of the large and small ends of the flat ingot in the thickness and width directions.

[0013] To ensure the accuracy and reliability of material tracking, in step S3, the determination of the validity of the rolling pass based on the material position signal is as follows: when the hot metal detector detects that the tail end of the flat ingot has completely left the preset position on the mill exit side, the system determines that the rolling pass has been effectively completed; if the signal is not detected within the preset time window, it is determined to be an abnormal pass and an alarm or process adjustment procedure is triggered.

[0014] In order to adapt the rolling speed to the process conditions, in step S4, the linear speed value is set according to the flat ingot material, temperature and size parameters.

[0015] In order to maintain a strictly uniform speed during the dynamic rolling process, step S4, the uniform speed rolling process, also includes real-time monitoring of the roll speed and the flat ingot movement speed by the rolling mill control system, and dynamic fine-tuning to maintain a constant rolling line speed.

[0016] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: This invention establishes a complete closed-loop automatic control scheme by constructing a wedge-shaped mathematical model, setting dedicated leveling passes, using position signals to determine the validity of passes, and uniformly controlling the rolling speed. This eliminates the reliance on operator experience, enabling the stable and continuous automatic execution of the wedge-shaped ingot rolling process, significantly improving production efficiency and product consistency.

[0017] To address the unreliable rolling force feedback during small-end rolling, this invention uses the position signal from a hot metal detector as the basis for determining the validity of a pass. This method can reliably capture the actual position of the flat ingot, accurately determining the pass completion status even in the absence of significant rolling force feedback during small-end rolling. This solves the problem of material tracking interruption and provides a reliable data foundation for fully automated rolling.

[0018] During the leveling and rolling stage, by implementing a uniform speed rolling mode with "zero acceleration", the frictional force distribution between the rolls and the flat ingot is stabilized, the uneven force caused by speed fluctuations is eliminated, and slippage and skewness are avoided. This significantly improves the thickness uniformity, width accuracy and flatness of the rolled plate, and enhances the quality grade of the final product.

[0019] The rolling method in this invention can generate personalized rolling procedures according to the specific size and process conditions of each flat ingot. It is highly adaptable, does not require large-scale modification of existing rolling mill hardware, and has the advantages of low cost, easy implementation and promotion. Attached Figure Description

[0020] The following sections will describe some specific embodiments of the invention in a detailed manner 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 method for automatically rolling flat ingots using a reversible four-roll mill for medium-thick plates provided by the present invention. Figure 2 This is a step diagram of the method for automatically rolling flat ingots using a reversible four-roll mill for medium-thick plates 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] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] 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.

[0024] Figure 1 This is a flowchart illustrating the method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates, as provided by the present invention. This method achieves high-precision, fully automated rolling of flat ingots with wedge-shaped structures in both the thickness and width directions through systematic process modeling, strategy optimization, and real-time control.

[0025] Specifically, see Figure 2 The process includes the following steps: S1: Parameter Acquisition and Procedure Generation. The system first acquires the geometric characteristic parameters of the target flat ingot, specifically including the thickness of the large end (H1), the thickness of the small end (H2), the width of the large end (W1), the width of the small end (W2), and the total length of the flat ingot (L). Simultaneously, process parameters such as the ingot material type and the initial rolling temperature are also important inputs. Based on these parameters, the rolling mill control system constructs a three-dimensional wedge-shaped mathematical model of the flat ingot. Combining the target finished product dimensions (such as target thickness and width) and process conditions, it automatically calculates and generates a complete, personalized rolling procedure that includes the reduction amount for each pass, providing a precise process benchmark for subsequent automated execution.

[0026] S2: Rolling Strategy Execution and Leveling Process. This step uses the conventional EXBXL rolling strategy as the basic framework, and, considering the structural characteristics of the wedge-shaped flat ingot, adds at least two dedicated leveling rolling passes in its initial rolling stage (i.e., the extension stage). The core function of these two passes is to systematically correct and homogenize the initial wedge-shaped deviations of the flat ingot in the thickness and width directions, aiming to reduce the dimensional differences between the large and small ends, and to provide intermediate billets with relatively regular shapes and more uniform dimensions for subsequent conventional rolling stages, thereby significantly reducing the control difficulty and instability of the subsequent rolling process.

[0027] S3: Validity determination of rolling passes based on material position signals. In the execution of at least two leveling rolling passes, this example changes the existing method of determining pass validity based on rolling force signals. Instead, hot metal detectors located at the mill inlet and outlet sides are used to collect material position signals in real time, thereby performing logical judgments on the validity of rolling passes.

[0028] The specific logic for determining the validity of the aforementioned rolling pass is as follows: when the hot metal detector on the exit side detects that the tail end of the flat ingot has completely left its preset monitoring position, the system determines that the rolling pass has been effectively completed; if no corresponding departure signal is detected within the preset time window, the system determines that the pass is abnormal and automatically triggers an alarm mechanism or initiates a predefined process adjustment procedure (such as pass repetition or procedure correction). This improvement solves the material tracking failure problem caused by small contact area, weak or no rolling force feedback when rolling the small end of the flat ingot, ensuring the continuity and reliability of the entire automated process.

[0029] Step S4: Uniform Speed ​​Rolling and Dynamic Speed ​​Control. To prevent slippage and skewness that may occur due to uneven stress during the leveling rolling stage, the mill is controlled to perform uniform rolling at a constant linear speed in at least two leveling passes, and the system strictly maintains the rolling acceleration at 0 m / s². 2 The specific linear speed value is dynamically adjusted and set based on the material properties of the flat ingot, the real-time rolling temperature, and the actual dimensional parameters of the current pass.

[0030] To achieve a true "zero acceleration" uniform speed state, this example also uses a control system to monitor the roll speed and the actual movement speed of the flat ingot in real time, and dynamically fine-tune the roll speed based on the deviation between the two, thereby maintaining the preset constant rolling line speed, ensuring stable friction, and avoiding process instability caused by speed fluctuations.

[0031] The present invention will be further illustrated below through specific embodiments: Example

[0032] This embodiment uses a certain type of reversible medium-thick plate four-roll mill to roll a batch of wedge-shaped flat ingots. The flat ingots are made of 30Cr13 stainless steel. The large end dimensions are: thickness 460mm and width 1400mm; the small end dimensions are: thickness 443mm and width 1210mm; the target finished product thickness is 130mm and width 1700mm.

[0033] The automated rolling process, using the method disclosed in this example, involves the following steps: 1. Rolling Plan Formulation: The above-mentioned flat ingot size parameters are entered into the rolling mill control system, along with the material 30Cr13, initial rolling center temperature of 1180℃, and target finished product size. Based on these inputs, the control system then constructs a wedge-shaped mathematical model of the flat ingot and automatically calculates the reduction for each pass. Specifically, two dedicated leveling passes are set for the extension stage, with reductions of 18mm and 23mm respectively for these two leveling rolling passes. Subsequent conventional rolling stages automatically allocate reductions according to the EXBXL strategy.

[0034] 2. Rolling Strategy Execution: The flat ingot is fed into the rolling mill, and the automatic rolling program is started. The first two passes of leveling rolling are performed in the extended stage. The first pass performs preliminary leveling to address the thickness and width deviations of the large and small ends of the flat ingot. The second pass further refines the leveling effect, reduces the size difference between the large and small ends, and lays the foundation for subsequent rolling.

[0035] 3. Valid pass determination: During the two-pass leveling rolling process, the validity of the pass is determined by the position determination method. Even if there is no obvious rolling force feedback when rolling the small end, the position signal can still be accurately determined to avoid interruption of material tracking.

[0036] 4. Speed ​​Control: The two-pass leveling rolling process adopts a uniform speed mode, with the rolling speed set at 1.5 m / s. The control system maintains the acceleration at 0 m / s through closed-loop control. 2 The system monitors the roll speed and the flat ingot movement speed in real time, dynamically fine-tunes the speed, ensures uniform rolling, and prevents slippage and skewness throughout the process.

[0037] 5. Subsequent rolling: After the leveling rolling in the extension stage is completed, the rolling mill performs subsequent rolling passes according to the preset EXBXL rolling strategy until the target finished product size (thickness 130mm, width 1700mm) is achieved.

[0038] Implementation Results: Online testing and final inspection revealed that the batch of 30Cr13 stainless steel sheets rolled using the method of this invention exhibited consistently stable thickness tolerances within ±0.5mm and width tolerances within ±2mm. The sheets were straight and free from defects such as skewness, warping, and surface cracks. The entire rolling process, from the first pass to the last, required no manual intervention, achieving fully automated rolling. Production data showed that the efficiency of this automated rolling process increased by over 40% compared to the original manual operation mode, demonstrating significant advantages in product quality consistency, production stability, and labor productivity.

[0039] 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 method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates, characterized in that, Includes the following steps: S1: Obtain the geometric feature parameters of the target flat ingot, and based on the geometric feature parameters, construct a three-dimensional wedge mathematical model of the flat ingot in the rolling mill control system, automatically calculate and generate a rolling schedule containing multiple passes of reduction. S2: A rolling program based on the EXBXL strategy is adopted, and at least two dedicated leveling rolling passes are set in the initial rolling stage of the program to preliminarily correct and homogenize the wedge size deviation of the flat ingot in the thickness and width directions. S3: During the execution of the at least two leveling rolling passes, based on the material position signals collected by the hot metal detectors arranged on the inlet and outlet sides of the mill, it is determined whether the current rolling pass has been effectively completed. S4: During the execution of the at least two leveling rolling passes, the rolling mill is controlled to perform uniform rolling at a constant linear velocity, and the rolling acceleration is maintained at 0 m / s². 2 This is to stabilize the friction between the rolls and the flat ingot, and to prevent slippage and skew.

2. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1, characterized in that, In step S1, the geometric feature parameters include at least the thickness of the large end (H1), the thickness of the small end (H2), the width of the large end (W1), the width of the small end (W2), and the length of the flat ingot (L).

3. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1, characterized in that, In step S1, during the automatic calculation and generation of the rolling schedule, the reduction amount is also calculated in combination with the target finished product size and process parameters. The process parameters include at least the material type of the flat ingot and the initial rolling temperature.

4. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1, characterized in that, In step S2, the total reduction of the at least two leveling rolling passes is determined based on the initial wedge deviation values ​​of the large and small ends of the flat ingot in the thickness and width directions.

5. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1, characterized in that, In step S3, the determination of the validity of the rolling pass based on the material position signal is as follows: when the hot metal detector detects that the tail end of the flat ingot has completely left the preset position on the mill exit side, the system determines that the rolling pass has been effectively completed; if the signal is not detected within the preset time window, it is determined to be an abnormal pass and an alarm or process adjustment procedure is triggered.

6. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1, characterized in that, In step S4, the linear velocity value is set according to the flat ingot material, temperature, and size parameters.

7. The method for automatically rolling flat ingots using a reversible four-high rolling mill for medium-thick plates according to claim 1 or 6, characterized in that, In step S4, the uniform rolling process also includes real-time monitoring of the roll speed and the flat ingot movement speed through the rolling mill control system, and dynamic fine-tuning to maintain a constant rolling line speed.

Images