A control method for tension and rolling force matching process of continuous annealing six-high cold rolling skin pass mill

Abstract

The application discloses a kind of continuous annealing six-roll cold-rolled skin tension and rolling force matching process control method, belong to cold-rolled strip steel production control method field.The application first monitors and tracks actual production line production data, triggers calculation logic when the weld position of next volume strip steel and current strip steel is 100 meters away from the position of skin machine, specific calculation method is based on strip steel thickness, width, strip steel target elongation, calculates the strip steel inlet tension, outlet tension.Again, solve the optimal rolling force using random forest model, and when next volume strip steel is about to enter the skin process, the optimal rolling force is issued to the field control PLC, and at the same time, the size of rolling force is adjusted according to the change of field parameters, to realize the optimal rolling force production matched with other tension, until the strip steel completes the skin process.Implementation improves the surface quality of strip steel, avoids producing roll mark, prevents the purpose of strip breakage.

Description

Technical Field

[0001] This invention belongs to the field of production technology of flattened strip steel using a continuous six-roll cold rolling leveling machine, and relates to an adjustment method for maintaining optimal rolling force during the leveling process of a cold rolling production line. Background Technology

[0002] The rolling force of the leveling mill in a continuous six-roll cold rolling mill is a key process parameter for cold-rolled strip steel, which has a significant impact on the surface quality of the strip steel products. Figure 1 The diagram shows a simplified layout of a six-roll cold rolling leveling mill in the prior art. Tension rolls 2, anti-wrinkle rolls 3, and anti-vibration rolls 4 are arranged before and after the leveling mill 1. The strip 5 is leveled at the leveling mill 1. The main control parameters of the leveling process are the leveling rolling force and the tension before and after leveling. The main control objectives of the leveling process are the elongation and surface quality of the steel coil. The rationality of the rolling force setting directly affects the elongation and the surface quality of the product. During production, the rolling force is characterized by fluctuations, mismatch with the inlet and outlet tensions, and difficulty in accurately establishing mathematical models.

[0003] Currently, most steel mills in China use a lookup table method or rely on operator experience and production requirements to set the rolling force during the leveling process in their six-roll continuous annealing cold rolling lines. This results in significant deviations between the set and actual rolling force, leading to fluctuations in elongation and adversely affecting product performance and surface roughness. In severe cases, it can even cause strip breakage. Orowan first discovered a "flattened zone" in the middle of the contact arc under certain rolling conditions, where the reduction is almost zero. Several scholars, including Lian Jiachuang and Fleck, proposed dividing the contact arc length between the roll and strip into multiple zones to distinguish between elastic and plastic deformation. They argued that a large "flattened elastic deformation zone" exists within the roll gap deformation zone, generally divided into an "entry elastic zone," an "exit elastic zone," and a "plastic deformation zone." Based on the assumption of the contact pressure distribution function, the length of the "exit elastic zone" is iteratively calculated to ultimately determine the total rolling force.

[0004] However, computational models based on deformation mechanisms require a large number of iterative calculations, which are time-consuming and have difficulty converging, making them unsuitable for online control.

[0005] Patent application number 202110860147.8 discloses a method and device for obtaining rolling force of a leveling mill. It uses multiple sets of historical leveling mill rolling data to build a model and obtain rolling force parameters. However, it has significant limitations, especially since the obtained rolling force parameters fluctuate when process parameters change. Patent application number 202010140608.X discloses a method for obtaining leveling mill parameters that is only suitable for continuous production of the same steel grade and size; it cannot meet the requirements when switching steel grades or strip sizes. The accuracy of the online leveling rolling force calculation model, whether using the Roberts model or the Brandford model, hinges on how accurately the parameters regarding contact arc length and deformation resistance are determined. How to obtain more accurate leveling rolling force settings is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a rolling force control method for a continuous six-roll cold-rolled strip leveling mill, so as to solve the technical problem that the rolling force obtained by the existing method differs greatly from the actual rolling force.

[0007] To achieve the above objectives, the present invention mainly adopts the following technical solutions: A method for controlling the tension and rolling force matching process of a continuous six-roll cold rolling leveling mill includes the following steps: (1) Collect actual production data from the cold rolling production line; (2) Monitor production line tracking data, read PLC data of field control, and jump to step (3) when the weld position of the next strip and the current strip is about to reach the six-roll leveler. (3) Calculate the inlet tension and outlet tension of strip steel with different dimensions and target elongation respectively. The setting of the inlet tension and outlet tension depends on the calculation of the random forest model. The input parameters of the model are strip steel width, thickness and target elongation, and the output parameters are inlet tension and outlet tension. (4) Calculate the optimal rolling force based on the strip size, target elongation, inlet tension, and outlet tension. The formula for calculating the optimal rolling force is obtained by linear regression of the field data. The optimal rolling force function is: ; In the formula, For strip thickness, For strip width, For the target elongation rate, and These are the inlet tension and outlet tension of the strip, respectively. (5) Store the optimal rolling force calculated in step (4) into the PLC data block. When the weld position of the next coil of steel and the current coil of strip steel reaches the leveling machine, trigger judgment is made. According to the strip steel production requirements, namely the tension, size and target elongation of the strip steel, the optimal rolling force parameters are selected. At this time, the new coil of strip steel enters the leveling process. (6) Detect whether the strip tension changes during the leveling process. If it changes, adjust the rolling force accordingly to keep the rolling force at the optimal rolling force that matches the inlet tension and outlet tension. (7) The strip tail is leveled, the control process of this coil ends, and the rolling force parameters of the next coil are executed at the same time.

[0008] In the above method, in step (2), when the weld position of the next strip and the current strip is 100 meters in front of the leveling machine, the process jumps to step (3).

[0009] In the above method, if the inlet tension and outlet tension change during the leveling process in step (6), return to step (4) to recalculate and adjust the rolling force so that the optimal rolling force parameter matches the inlet tension and outlet tension.

[0010] The technical solution of this invention has the following advantages through the reasonable setting and control of the rolling force of the strip steel when it passes through the leveling mill: This invention addresses the deficiencies in existing calculation models for rolling force in cold-rolled strip steel processes by providing a control method for matching tension and rolling force in a continuous six-roll cold-rolling leveling mill. This invention monitors and tracks production line data, calculates the strip's inlet and outlet tensions based on strip thickness, width, and target elongation, and then uses a random forest model to solve for the optimal rolling force. As the next coil of strip is about to enter the leveling process, the optimal rolling force is sent to the on-site control PLC, and the rolling force is adjusted simultaneously according to changes in on-site parameters to achieve optimal rolling force production that matches other tensions. This method effectively reduces surface quality problems in cold-rolled strip steel products, avoids roll marks, prevents strip breakage accidents, and is simple and easy to implement. Attached Figure Description

[0011] Figure 1 is a schematic diagram of the layout of a six-roll continuous annealing cold rolling leveling mill. 1 represents the main body of the leveling mill, 2 is the tension roll, 3 is the anti-wrinkle roll, 4 is the anti-vibration roll, and 5 represents the strip steel in production.

[0012] Figure 2 is a schematic diagram of a random forest model for calculating inlet and outlet tensions. 1 represents the input layer, and 2 represents the output layer.

[0013] Figure 3 shows the rolling force curves of the existing leveling machine production process and the production process described in this invention when passing through the weld seam. In this figure, A represents the rolling force curve using the existing leveling machine production process, and B represents the optimal rolling force curve using the production process described in this invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0015] This invention provides a control method for the tension and rolling force matching process of a continuous six-roll cold rolling leveling mill. The method involves monitoring and tracking production line data, calculating the strip's inlet and outlet tensions based on strip thickness, width, and target elongation, and then using a random forest model to solve for the optimal rolling force. As the next coil of strip is about to enter the leveling process, the optimal rolling force is sent to the on-site control PLC, and the rolling force is adjusted simultaneously according to changes in on-site parameters to achieve optimal rolling force matching with other tensions. This method effectively reduces surface quality problems in cold-rolled strip products, avoids roll marks, prevents strip breakage accidents, and is simple and easy to implement.

[0016] The method for accurately obtaining the optimal rolling force of strip steel when the weld seam passes through the leveling machine according to the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the specific embodiments and related descriptions do not constitute an improper limitation on the technical solution of the present invention.

[0017] Example 1 A method for controlling the tension and rolling force matching process of a continuous six-roll cold rolling leveling mill includes the following steps: (1) Collect actual production data from the cold rolling production line; (2) Monitor production line tracking data, read PLC data of field control, and jump to step (3) when the weld position of the next strip and the current strip is about to reach the six-roll leveler. (3) Calculate the inlet tension and outlet tension of strip steel with different dimensions and target elongation respectively. The setting of the inlet tension and outlet tension depends on the calculation of the random forest model. The input parameters of the model are strip steel width, thickness and target elongation, and the output parameters are inlet tension and outlet tension. (4) Calculate the optimal rolling force based on the strip size, target elongation, inlet tension, and outlet tension. The formula for calculating the optimal rolling force is obtained by linear regression of the field data. The optimal rolling force function is: ; In the formula For strip thickness, For strip width, For the target elongation rate, and These are the inlet and outlet tensions of the strip, respectively. The optimal rolling force matching the strip tension is determined using a model. ; (5) Store the optimal rolling force calculated in step (4) into the PLC data block. When the weld position of the next coil of steel and the current coil of strip steel reaches the leveling machine, trigger judgment is made. According to the strip steel production requirements, namely the tension, size and target elongation of the strip steel, the optimal rolling force parameters are selected. At this time, the new coil of strip steel enters the leveling process. (6) Detect whether the strip tension changes during the leveling process. If it changes, adjust the rolling force accordingly to keep the rolling force at the optimal rolling force that matches the inlet tension and outlet tension. (7) The strip tail is leveled, the control process of this coil ends, and the rolling force parameters of the next coil are executed at the same time.

[0018] Example 2 The invention will be further described in conjunction with the company's actual production and the accompanying drawings.

[0019] Control the strip elongation during weld seam passing through the leveling machine according to the following steps: (1) By connecting to the site PLC Collect production process data for the six-roll leveling machine on-site for cold-rolled strip steel; (2) Establish a random forest model with strip width, thickness and target elongation as inputs and inlet tension and outlet tension as outputs. Use the data collected in (1) to train the random forest model. (3) Establish a linear regression model using the strip dimensions and target elongation from (1) and the inlet and outlet tensions output from the random forest in (2): , In the formula For strip thickness, For strip width, For the target elongation rate, and These are the inlet and outlet tensions of the strip, respectively. The optimal rolling force matching the strip tension is determined using a model. The optimal rolling force is obtained based on the condition that the elongation meets the target value; therefore, using the optimal rolling force for leveling can effectively reduce the time of the low rolling process. At the same time, the optimal rolling force matches different strip tensions. When the strip tension changes, the rolling force is readjusted to the corresponding optimal rolling force, resulting in more stable and uniform surface quality and strip shape; reducing the probability of strip breakage accidents. (4) When the strip is about to enter the six-roll cold rolling mill, it is checked on-site. PLC Read information about the strip steel; width w =1270mm, thickness t = 1.2mm, target elongation = 1. The strip inlet tension was calculated using the random forest model in (2). = 58.06 KN, outlet tension = 60.66 kN; (5) Use the linear regression model in (3) to find the optimal rolling force. = 6760 kN, through field PLC Send parameters to the device; (6) Check whether the strip tension changes during the leveling process. If it changes, repeat steps (4) and (5) to keep the rolling force at the optimal rolling force that matches the inlet tension and outlet tension. (7) End.

[0020] Figure 3 shows the rolling force curves when passing through the weld seam using both the existing leveling machine production process and the production process described in this invention. In this figure, A represents the rolling force curve using the existing leveling machine production process, and B represents the optimal rolling force curve using the production process described in this invention. Figure 3 It can be seen that the optimal rolling force curve B during the production of this invention has a shorter low rolling distance, which means that the strip elongation is not consistent with the length, thus improving the steel utilization rate and production efficiency, while reducing production costs to a certain extent.

[0021] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the scope of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for controlling the tension and rolling force matching process of a continuous six-roll cold rolling leveling mill, characterized in that: The method includes the following steps: (1) Collect actual production data from the cold rolling production line; (2) Monitor production line tracking data, read PLC data of field control, and jump to step (3) when the weld position of the next strip and the current strip is about to reach the six-roll leveler. (3) Calculate the inlet tension and outlet tension of strip steel with different dimensions and target elongation respectively. The setting of the inlet tension and outlet tension depends on the calculation of the random forest model. The input parameters of the model are strip steel width, thickness and target elongation, and the output parameters are inlet tension and outlet tension. (4) Calculate the optimal rolling force based on the strip size, target elongation, inlet tension, and outlet tension. The formula for calculating the optimal rolling force is obtained by linear regression of the field data. The optimal rolling force function is: In the formula, t is the strip thickness, w is the strip width, μ is the target elongation, and t f与 t b These are the inlet tension and outlet tension of the strip, respectively. (5) Store the optimal rolling force calculated in step (4) into the PLC data block. When the weld position of the next coil of steel and the current coil of strip steel reaches the leveling machine, trigger judgment is made. According to the strip steel production requirements, namely the tension, size and target elongation of the strip steel, the optimal rolling force parameters are selected. At this time, the new coil of strip steel enters the leveling process. (6) Detect whether the strip tension changes during the leveling process. If it changes, adjust the rolling force accordingly to keep the rolling force at the optimal rolling force that matches the inlet tension and outlet tension. (7) The strip tail is leveled, the control process of this coil ends, and the rolling force parameters of the next coil are executed at the same time.

2. The control method for tension and rolling force matching process of a continuous six-roll cold rolling leveling mill according to claim 1, characterized in that: In step (2), when the weld seam between the next strip and the current strip is 100 meters in front of the leveling machine, jump to step (3).

3. The method for controlling the tension and rolling force matching process of a continuous six-roll cold rolling leveling mill according to claim 1, characterized in that: In step (6), if the inlet tension and outlet tension change during the leveling process, return to step (4) to recalculate and adjust the rolling force so that the optimal rolling force parameter matches the inlet tension and outlet tension.

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