A method for improving the setting precision of the initial roll gap of a hot continuous rolling finishing roll changing

Abstract

The application provides a method for improving the precision of initial roll gap setting of strip hot continuous rolling finishing roll changing, and relates to the technical field of hot continuous rolling automatic control. The method first collects and adds the roll gap short-term self-learning quantity of the first three strips before each stand after finishing roll changing to obtain an average value; if the thickness deviation value of the head thickness gauge of the first strip after roll changing is greater than 0.1mm, the average value of the short-term self-learning quantity of the roll gap of the first three strips is compensated; when the next roll changing is performed, the initial roll gap short-term self-learning quantity adopts the average value of the short-term self-learning quantity of the roll gap of the first three strips after the last roll changing. If the thickness deviation value of the head thickness gauge of the first strip after roll changing is not greater than 0.1mm, the initial roll gap short-term self-learning quantity adopts the compensated average value. Through the method, the actual application effect in the field shows that the thickness deviation value after finishing roll changing is effectively reduced, the appearance size control level of the strip head and the thickness yield rate are both improved.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for hot strip rolling, and in particular to a method for improving the initial roll gap setting accuracy of hot strip rolling finishing roll change. Background Technology

[0002] In the hot strip rolling production line, the finishing mill stands use short-term self-learning of the roll gap to buffer the changes in mill bounce caused by work roll wear, work roll thermal expansion, and work roll shifting. This ensures accurate calculation of the roll gap between the two stands, ultimately avoiding large thickness deviations and guaranteeing product quality.

[0003] The mismatch in flow rate between stands caused by the accuracy error of the roll gap setting model in the process control system after roll change, resulting in the phenomenon of steel piling up, especially the large thickness deviation caused by the inability of the roll gap to be raised or lowered quickly, is usually difficult to solve.

[0004] In practice, operators can alleviate thickness difference problems by adjusting the roll gap of the last stand in advance before threading the strip. However, since the operator's correction range is limited, the amount of raising or lowering the roll gap can only be determined by experience. Excessive adjustment will seriously affect the dimensional accuracy of the strip head, such as thickness and width, and cause abnormal data collected by the secondary model system, affecting the model's self-learning and thus exacerbating the large thickness deviation. Summary of the Invention

[0005] To address the aforementioned technical problems in existing technologies, this invention provides a method for improving the initial roll gap setting accuracy during hot strip rolling mill finishing mill roll changes. This method involves collecting the short-term self-learning values ​​of the first three roll gaps on each stand after a roll change and calculating their average value. The average value is then used as the initial short-term self-learning value for the roll gap after the next roll change, thereby improving the model's accuracy. The technical solution is as follows:

[0006] A method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill, the method comprising: S1. After the finishing mill stand changes rolls, collect the short-term self-learning values ​​of the roll gaps of the first three roll gaps of the roll changing stand. S2. Add up the short-term self-learning values ​​of the first three roll gaps collected in S1 and calculate the average value. S3. Determine whether the absolute value of the thickness deviation of the first steel head after the roll change is greater than 0.1mm; S4. If the absolute value of the deviation in S3 is greater than 0.1mm, then the average value of the short-term self-learning values ​​of the first three roll gaps obtained in S2 will be compensated during the next roll change. S5. If the absolute value of the deviation determined in S3 is not greater than 0.1mm, then the short-term self-learning value of the initial roll gap during the next roll change shall be the average value obtained in S2.

[0007] The short-term self-learning value of the roll gap in S1 is the deviation between the measured roll gap and the measured thickness.

[0008] The average value calculation process in S2 is as follows: in, This represents the average value of the short-term self-learning amount of the gap between the first three rolls after the roll change. , , These are the short-term self-learning values ​​of the roll gap for the first three rolls after the roll change. This is the rack number.

[0009] The specific judgment process in S3 is as follows: The sampling start point is 5 meters from the head of the finished product, the sampling cycle is 0.1 seconds, and the number of sampling points is 10. The average value of the 10 points is calculated as the head thickness deviation, and then it is determined whether the absolute value of the deviation is greater than 0.1 mm.

[0010] The calculation process for the compensation amount in S4 is as follows: in, This is the compensation amount for the short-term self-learning value of the initial roll gap for the next roll change. The compensation coefficient is different for each rack; for racks F1 to F6, the compensation values ​​are 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 respectively. The thickness deviation is due to the thickness gauge head. The number of stands for the finishing mill roll changing. This is the rack number.

[0011] The compensation specifically refers to: in, This is the initial roll gap short-term self-learning value for roll changing. This represents the average short-term self-learning value of the gap between the first three rolls after the roll change. This is the compensation amount for the short-term self-learning value of the initial roll gap for the next roll change. This is the rack number.

[0012] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In the above scheme, the short-term self-learning value of the first three roll gaps of each stand after roll change is collected and the average value is calculated. The average value is used for the initial short-term self-learning value of the roll gap after the next roll change, thereby improving the accuracy of the model. This method effectively reduces the thickness deviation value after strip threading in the finishing mill, and improves the control level of the strip head's shape dimensions and the thickness yield. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to an embodiment of the present invention; Figure 2 This is a comparison of the deviation between the roll gap setting and the actual thickness and the set thickness in the embodiments of the present invention before and after using the initial roll gap short-term self-learning, wherein (a) is a comparison of the thickness deviation before the optimization of the method of the present invention is applied, and (b) is a comparison of the thickness deviation after the method of the present invention is applied. Detailed Implementation

[0015] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0016] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0017] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0018] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0019] This invention provides a method for improving the initial roll gap setting accuracy during hot strip rolling finishing. For example... Figure 1 The flowchart shown illustrates a method for improving the initial roll gap setting accuracy during hot strip finishing mill roll changing. This method may include the following steps:

[0020] S1. After the finishing mill stand changes rolls, collect the short-term self-learning values ​​of the roll gaps of the first three roll gaps of the roll changing stand. S2. Add up the short-term self-learning values ​​of the first three roll gaps collected in S1 and calculate the average value. S3. Determine whether the absolute value of the thickness deviation of the first steel head after the roll change is greater than 0.1mm; S4. If the absolute value of the deviation in S3 is greater than 0.1mm, then the average value of the short-term self-learning values ​​of the first three roll gaps obtained in S2 will be compensated during the next roll change. S5. If the absolute value of the deviation determined in S3 is not greater than 0.1mm, then the short-term self-learning value of the initial roll gap during the next roll change shall be the average value obtained in S2.

[0021] The average value in S2 is calculated as follows: in, This represents the average value of the short-term self-learning amount of the gap between the first three rolls after the roll change. , , These are the short-term self-learning values ​​of the roll gap for the first three rolls after the roll change. This is the rack number.

[0022] The compensation is as follows: in, This is the initial roll gap short-term self-learning value for roll changing. This is the compensation amount for the short-term self-learning value of the initial roll gap for the next roll change.

[0023] The compensation calculation process is as follows: in, For compensation coefficient, The thickness deviation is due to the thickness gauge head. This refers to the number of stands for the finishing mill roll changing.

[0024] In practical applications, all seven stands of the hot strip finishing mill undergo roll changes. The thickness deviation of the first steel strip is 0.15mm. Taking the F1 stand as an example, the short-term self-learning values ​​of the roll gap for the first three stands are 0.1474mm, 0.1801mm, and 0.2137mm, respectively. The average value in S2 is: Thickness gauges were used to collect data starting 5 meters from the top of the finished product, with one point collected every 0.1 seconds. The thicknesses at 10 points were 3.538 mm, 3.558 mm, 3.571 mm, 3.558 mm, 3.553 mm, 3.553 mm, 3.543 mm, 3.539 mm, 3.548 mm, and 3.539 mm, respectively. After collecting data at 10 points, the average thickness of the 10 points was subtracted from the target thickness value (3.4 mm), resulting in a thickness deviation of 0.15 mm. Since the absolute value of the deviation was greater than 0.1 mm, compensation was applied to the average value. The compensation amount was calculated as follows: The compensated initial roll gap short-term self-learning value is as follows: When the current frame sets the roll gap based on the exit thickness, the obtained self-learning value is directly added to quickly offset the thermal expansion, wear, oil film thickness and frame bounce of the roll system after the roll change.

[0025] This invention provides a method for improving the initial roll gap setting accuracy during hot strip rolling mill finishing. It comprehensively considers the constraints of all aspects of the rolling mill system. This method has been applied to a hot strip rolling production line in China. The roll gap settings before and after application are as follows: Figure 2 As shown (F7 mill roll gap selected, target thickness set to 3.4mm). Data such as the mill roll gap and the actual thickness measured by the thickness gauge during the rolling process were recorded by a PDA, with a sampling period of 10 ms. It can be seen that before optimization using this method ( Figure 2 (a) The large actual thickness deviation indicates that the roll gap setting of frame F7 is too large. After optimization using this method ( Figure 2 (b) corrected the initial roll gap short-term self-learning. Since the initial roll gap setting calculation was accurate, no large thickness deviation occurred.

[0026] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill roll change, characterized in that, The method includes: S1. After the finishing mill stand changes rolls, collect the short-term self-learning values ​​of the roll gaps of the first three roll gaps of the roll changing stand. S2. Add up the short-term self-learning values ​​of the first three roll gaps collected in S1 and calculate the average value. S3. Determine whether the absolute value of the thickness deviation of the first steel head after the roll change is greater than 0.1mm; S4. If the absolute value of the deviation in S3 is greater than 0.1mm, then the average value of the short-term self-learning values ​​of the first three roll gaps obtained in S2 will be compensated during the next roll change. S5. If the absolute value of the deviation determined in S3 is not greater than 0.1mm, then the short-term self-learning value of the initial roll gap during the next roll change shall be the average value obtained in S2.

2. The method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to claim 1, characterized in that, The short-term self-learning value of the roll gap in S1 is the deviation between the measured roll gap and the measured thickness.

3. The method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to claim 1, characterized in that, The average value calculation process in S2 is as follows: in, This represents the average value of the short-term self-learning amount of the gap between the first three rolls after the roll change. , , These are the short-term self-learning values ​​of the roll gap for the first three rolls after the roll change. This is the rack number.

4. The method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to claim 1, characterized in that, The specific judgment process in S3 is as follows: The sampling start point is 5 meters from the head of the finished product, the sampling cycle is 0.1 seconds, and the number of sampling points is 10. The average value of the 10 points is calculated as the head thickness deviation, and then it is determined whether the absolute value of the deviation is greater than 0.1 mm.

5. The method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to claim 1, characterized in that, The calculation process for the compensation amount in S4 is as follows: in, This is the compensation amount for the short-term self-learning value of the initial roll gap for the next roll change. For compensation coefficient, The thickness deviation is due to the thickness gauge head. The number of stands for the finishing mill roll changing. This is the rack number.

6. The method for improving the initial roll gap setting accuracy of hot strip rolling finishing mill according to claim 5, characterized in that, The compensation specifically refers to: in, This is the initial roll gap short-term self-learning value for roll changing. This represents the average short-term self-learning value of the gap between the first three rolls after the roll change. This is the compensation amount for the short-term self-learning value of the initial roll gap for the next roll change. This is the rack number.

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