A control method for preventing a mill frame from running off-center during a finish rolling process

Abstract

The application discloses a control method for preventing deviation of a rack in a finishing rolling process, which comprises the following steps: locking a rolling force deviation in a period after a head is rolled out at a fixed time as a stable rolling force deviation value, determining a real-time value of the rolling force deviation in a subsequent rolling process, calculating a difference value between the real-time value of the rolling force deviation and the stable rolling force deviation value until a flying shear cuts a tail, and automatically calculating a single-side roll gap leveling of a rolling mill according to a change of the difference value, so as to realize automatic leveling and deviation prevention in the finishing rolling process. The control method reduces manual intervention, reduces labor operation load, and improves stability and quality of the finishing rolling.

Description

Technical Field

[0001] This invention relates to hot rolling finishing process and is a control method for preventing stand deviation during the rolling process by automatically leveling the finishing rolling process. Background Technology

[0002] The stability of the finishing rolling process has a crucial impact on the stable operation of the production line. Many factors influence the stability of finishing rolling, such as the stability of the looper, the uniformity of the intermediate billet temperature, the range of bending roll force adjustment, and human intervention. Since there are no direct detection devices or automated control methods, the control of the plate shape between stands during the rolling process is all monitored and intervened in real time by operators. While obvious deviations can be detected and addressed manually, gradual, potential deviations are undetectable, which severely restricts the stable operation of the finishing mill.

[0003] The 2250 hot-rolled finishing mill lacks detection equipment and control models for preventing deviation during the rolling process, relying solely on operator observation and correction. During the rolling process, operators adjust the leveling and correction based on the plate shape fluctuations and deviations between stands, combined with their experience. Due to the high humidity and video delays during rolling, manual monitoring is difficult and labor-intensive. Inconsistent skill levels among finishing mill operators lead to variations in the magnitude and accuracy of corrections, resulting in significant stability fluctuations during finishing. Inaccurate observation and untimely leveling and correction between finishing mill stands increase the frequency of scrap deviation during rolling.

[0004] For similar production lines, the control of pre-leveling in the finishing mill is mainly based on the deviation curve of the slab centerline measured by the sickle bending measuring instrument. A plate shape detection device between the stands is installed above the F1-F4 stands. The detection results are numerically processed, the curve feature values ​​are extracted, the bending direction and degree of the intermediate slab tail are determined, and then the roll gap difference on both sides of the horizontal roll is calculated by combining the empirical model. Leveling is achieved by controlling the roll gap difference on both sides. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. By comparing the real-time rolling force deviation with the stable rolling force deviation during the rolling process, the deviation of the strip in each stand of the finishing mill is monitored, so as to realize the automatic leveling and anti-deviation method in the finishing mill rolling process, thereby reducing manual intervention, reducing the labor load of operation, and improving the stability of finishing mill.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for controlling stand deviation during finishing rolling, the method comprising the following steps:

[0008] S1. Rolling Force Deviation Locking: The rolling force deviation is locked at a fixed time for a period of time after the strip head is rolled out. This rolling force deviation is used as the stable rolling force deviation value ΔF. Ave ;

[0009] S2. Determine the real-time value ΔF of the rolling force deviation during subsequent rolling processes. Real ;

[0010] S3. Calculate the real-time value of rolling force deviation ΔF Real Deviation value ΔF from stable rolling force Ave The difference ΔF = ΔF Real - ΔF Ave Until the tail is cut off by the flying shear;

[0011] S4. Roll gap leveling on one side of the mill: Based on the change of ΔF in step S3, the roll gap on one side of the mill is automatically leveled. When ΔF is positive, it indicates that the strip is biased towards the working side, and the mill leveling presses the roll gap. Conversely, the mill leveling raises the roll gap, thereby automatically correcting the deviation during the process and achieving the purpose of preventing deviation. The leveling amount of the roll gap on one side of the mill is calculated by formula and is subject to the limitations of the roll gap leveling operation.

[0012] Furthermore, the rolling force deviation ΔF in step S1 Ave The locking method is as follows:

[0013] Starting 5 seconds after the strip bites at stand F7, 30 points are taken as the stable rolling force deviation ΔF for the current strip locking. Ave ;

[0014] Step S2 determines the real-time value ΔF of the rolling force deviation during the subsequent rolling process. Real The method is as follows:

[0015] Using a sliding filter, the average of 30 data points is used as the real-time value of the current rolling force deviation ΔF. Real .

[0016] Furthermore, the calculation formula for the leveling amount of the single-side roll gap in step S4 is as follows:

[0017] ,

[0018] In the formula: The leveling amount of the roll gap on one side of the rolling mill (mm); To adjust the impact coefficient; Width influence coefficient; This is the thickness influence coefficient; This represents the influence coefficient of the hardness group.

[0019] The limitations for using single-side roll gap leveling on the rolling mill are as follows: it is only used for strip steel with a thickness of 2.3mm ≤ 6.5mm, and the leveling stand is F1-6; for F1-3, leveling is not performed when |ΔF| ≤ 400, and the excess part is leveled; for F4-6, leveling is not performed when |ΔF| ≤ 300, and the excess part is leveled; the interval between two automatic leveling operations is 3s; after leveling, no restoration is performed, and the amount is directly superimposed with the amount of manual and wedge automatic leveling. When the flying shear tail is cut, the output of the existing leveling amount is locked and remains unchanged until the current stand throws the steel and then it is cleared to zero.

[0020] Furthermore, the single-sided roll gap leveling amount The limit is ±0.15mm.

[0021] The beneficial effects of this invention are: by obtaining the difference between the real-time deviation value and the stable deviation value of the rolling force during the rolling process, and by automatically calculating the leveling amount of the roll gap on one side of the mill, the mill stand is adjusted accordingly, thereby achieving automatic leveling and preventing deviation during the finishing rolling process. This control method reduces manual intervention, lightens the workload of manual operations, and improves the stability and quality of finishing rolling. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the frame structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the control flow of the control method of the present invention;

[0024] Figure 3 Example 1: Rolling parameters diagram of a certain rolled strip;

[0025] Figure 4 Example 2: Rolling parameters diagram of a certain rolled strip;

[0026] The labels in the figure are named as follows: 1-Stable rolling force deviation value; 2-Real-time rolling force deviation value; 3-Single-sided roll gap deviation value. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments, which are methods for controlling the deviation of the stand during the finishing rolling process. Example 1

[0028] A certain rolled strip has a hardness group of 1, a thickness of 3.52 mm, and a width of 1267 mm. After the strip is threaded, the model calculates the stable rolling force deviation value (line 1 in the figure). After locking, the difference between the real-time rolling force deviation value 2 and the stable rolling force deviation value 1 is calculated. Figure 3 As shown.

[0029] When deviation occurs, it corresponds to the position where the real-time rolling force deviation value 2 drops sharply in the diagram. At this time, the real-time rolling force deviation value 2 is lower than the set value of -400KN in the model. According to the calculation formula of the single-sided roll gap leveling amount and the limit, substituting the hardness group, thickness and width of the strip, the single-sided roll gap leveling amount is calculated to be 0.15mm. This single-sided roll gap leveling amount acts on the original single-sided roll gap deviation value 3, which is reflected in the position of sharp rise in the diagram. After the single-sided roll gap deviation value 3 is adjusted, the real-time rolling force deviation value 3 is improved, and a U-shaped recovery is shown in the diagram. The strip has played an effective role in correcting deviation under the action of single-sided roll gap adjustment, and the adjusted single-sided roll gap deviation value is maintained until the rolling is completed. Example 2

[0030] A certain rolled strip has a hardness group of 1, a thickness of 3.52 mm, and a width of 1250 mm. After the strip is threaded, the model calculates the stable rolling force deviation value (line 1 in the diagram). After locking, the difference between the real-time rolling force deviation value 2 and the stable rolling force deviation value 1 is calculated. Figure 4 As shown.

[0031] Since the absolute difference between the real-time rolling force deviation value 2 and the head stable rolling force deviation value is always within 400KN, according to the single-sided roll gap leveling operation restriction conditions, the correction amount is 0, that is, the original single-sided roll gap deviation value 3 is maintained to roll the strip.

[0032] The above content is only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for controlling stand deviation during finishing rolling, characterized in that: The method includes the following steps: S1. Rolling Force Deviation Locking: The rolling force deviation is locked at a fixed time for a period of time after the strip head is rolled out. This rolling force deviation is used as the stable rolling force deviation value ΔF. Ave ; S2. Determine the real-time value ΔF of the rolling force deviation during subsequent rolling processes. Real ; S3. Calculate the real-time value of rolling force deviation ΔF Real Deviation value ΔF from stable rolling force Ave The difference ΔF = ΔF Real -ΔF Ave Until the tail is cut off by the flying shear; S4. Roll gap leveling on one side of the mill: Based on the change of ΔF in step S3, the roll gap leveling on one side of the mill is performed automatically. When ΔF is positive, the mill leveling adjusts the pressure roll gap, and vice versa. The leveling amount of the roll gap on one side of the mill is calculated by formula and is subject to the limitations of the roll gap leveling operation. The formula for calculating the leveling amount of the single-side roll gap in step S4 is as follows: ， The leveling amount of the roll gap on one side of the rolling mill is expressed in mm. To adjust the impact coefficient; Width influence coefficient; This is the thickness influence coefficient; This represents the influence coefficient of the hardness group. The limitations for using the single-side roll gap leveling of the rolling mill are as follows: it is only used for strip steel with a thickness of 2.3mm ≤ 6.5mm, and the leveling stand is F1-6; for F1-3, leveling is not performed when |ΔF| ≤ 400, and the excess portion is leveled; for F4-6, leveling is not performed when |ΔF| ≤ 300, and the excess portion is leveled; the interval between two automatic leveling operations is 3 seconds; after leveling, there is no restoration, and the amount is directly superimposed with the amount of manual and wedge-shaped automatic leveling. When the flying shear tails the steel, the output of the existing leveling amount is locked and remains unchanged until the current stand throws the steel, at which point it is reset to zero; the leveling amount of the single-side roll gap of the rolling mill is... The limit is ±0.15mm.

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