A method for controlling the lateral deflection of work rolls in 4- and 6-roll rolling mills

Abstract

This invention relates to a method for controlling the lateral deflection of work rolls in 4- and 6-roll rolling mills, comprising the following steps: S1, calculating the rolling force and the front-to-back tension difference according to the rolling schedule; S2, calculating the roll eccentricity based on the front-to-back tension difference and the rolling force, with the target set to zero lateral force on the roll body; S3, adjusting the horizontal position of the work roll so that the offset between the work roll and the centerline of the support roll reaches the calculated value; S4, pressing down the roll, tensioning the strip, and checking the roll force condition detected by the horizontal force detector of the work roll bearing seat. If the force exceeds the set limit, the roll gap is opened to readjust the eccentricity; S5, starting rolling when the work roll body force is within the set range. This invention is adaptable to rolling various specifications and steel grades, has strong adaptability to the rolling environment, and controls the lateral force on the roll body within a certain range, effectively reducing lateral deflection of the roll body and obtaining a better strip shape.

Description

Technical Field

[0001] This invention relates to the field of strip processing technology, and more specifically, to a method for controlling the lateral deflection of work rolls in 4- and 6-roll rolling mills, applicable to 4- and 6-roll rolling mills. Background Technology

[0002] This technology is similar for 4- and 6-high rolling mills; this article uses a 4-high rolling mill as an example. During the rolling process in a 4-high rolling mill, the work rolls are prone to lateral swaying within the stand due to the influence of rolling force and tension, affecting rolling stability. To ensure the lateral stability of the work rolls, the centerlines of the support rolls and work rolls are generally designed to be eccentric, such as... Figure 1 The eccentric design ensures that the work roll always leans towards the archway side under the rolling force, without lateral swaying. During rolling, the work roll is subjected to the forces of the support roll, strip, and archway. The horizontal force on the roll body will cause a certain amount of lateral deflection. Deflection will seriously affect the rolling process, product quality, roll body and bearing life. The amount of deflection is mainly related to the magnitude of the force on the roll body and the roll diameter. This limits the roll diameter of the 4-high mill, preventing it from being too small. Currently, internationally, the amount of lateral deflection is controlled by limiting the size of the work roll. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for controlling the lateral deflection of the work rolls of 4- and 6-roll rolling mills. This method is adaptable to rolling of various specifications and steel grades, has strong adaptability to the rolling environment, and controls the lateral force on the roll body within a certain range, which can effectively reduce the lateral deflection of the roll body and obtain a better plate shape.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a method for controlling the lateral deflection of work rolls in 4- and 6-roll rolling mills, comprising the following steps:

[0005] S1. Calculate the rolling force and tension difference between the front and rear sides according to the rolling schedule;

[0006] S2. Calculate the roll eccentricity based on the front and rear tension difference of the strip and the rolling force value, with the target set to make the lateral force on the roll body zero.

[0007] S3. Adjust the horizontal position of the working roller so that the offset between the center line of the working roller and the support roller reaches the calculated value;

[0008] S4. Rolls are pressed down, strip is tensioned, and the roll stress detected by the horizontal force detector of the work roll bearing housing is checked. If the stress exceeds the set limit, the roll gap is opened and the eccentricity is corrected again.

[0009] S5. Rolling starts when the working roll body is under stress within the set range.

[0010] According to the above scheme, in step S2, the eccentricity e is calculated using the following formula:

[0011]

[0012] Where r is the work roll radius, R is the support roll radius, F0 is the rolling force, F2 is the horizontal component of the rolling force, T0 is the strip front tension, T1 is the strip back tension, and Fx is the unstable factor.

[0013] According to the above scheme, positioning devices are installed on the bearing seats on both sides of the work roll at the outlet end, and the positioning devices are used to position the work roll horizontally.

[0014] According to the above scheme, the positioning device includes a wedge adjustment block. A part of the wedge adjustment block is fixed on the mill stand, and the other part is driven to extend and retract by a hydraulic cylinder, thereby achieving left-side positioning of the roll bearing seat.

[0015] According to the above scheme, a thrust device is installed at the inlet end of the work roll, and a pressure sensor and a displacement sensor are installed inside the thrust device.

[0016] According to the above scheme, the thrust-stopping device is a pad pushed by a hydraulic cylinder. The hydraulic cylinder is installed on the right side of the archway. When the roll advances into the archway, the hydraulic cylinder extends and presses against the right side of the work roll, pressing the work roll tightly against the positioning device on the left side, thereby adjusting and fixing the position of the work roll center relative to the archway center.

[0017] The principle of this invention is as follows:

[0018] The main forces acting on the work rolls are strip tension, the rolling force of the support rolls, and other smaller external forces. Strip tension is set by the rolling process engineers according to the rolling specifications. The rolling force setting can be calculated based on strip strength, specifications, and reduction, but the actual rolling force is adjusted in real-time by the AGC (Automatic Gauge Control) system, resulting in a slight discrepancy between the calculated and actual values. The horizontal component of the rolling force is affected by the rolling force itself and the eccentricity between the work roll and the support roll. Adjusting the roll eccentricity adjusts the horizontal component of the rolling force on the work rolls. By comprehensively considering the horizontal component of the rolling force and the tension difference between the front and rear strip sections, adjusting the roll eccentricity controls the stress on the work rolls within a certain range, thereby reducing lateral deflection of the work rolls.

[0019] The lateral deflection control method for work rolls in 4- and 6-roll mills of the present invention has the following beneficial effects:

[0020] During steel rolling, the smaller the diameter of the work rolls, the lower the rolling force and torque required, and the less elastic flattening of the rolls. Therefore, small-diameter rolls are necessary when rolling high-strength strip steel. However, during rolling, the lateral force on the rolls causes them to flex laterally. Excessive flexing deformation severely affects the strip shape quality. The smaller the diameter of the work rolls, the greater their flexing deformation under lateral force. Therefore, the diameter of the work rolls in 4- and 6-roll mills is severely limited by the lateral flexing deformation of the rolls. Conventional wide strip steel 4- and 6-roll mills typically have work roll diameters of over 300 mm. The method of this invention can reduce the lateral force on the work rolls, allowing for the use of smaller work roll diameters.

[0021] The method of this invention is adaptable to rolling of various specifications and steel grades, and has a stronger adaptability to the rolling environment. It controls the lateral force on the roll body within a certain range, which can effectively reduce the lateral deflection of the roll body and obtain a better plate shape. It allows 4- and 6-roll mills to use smaller roll diameters. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the principle of a 4-roll or 6-roll rolling mill;

[0024] Figure 2 This is a schematic diagram of the equipment structure used in the lateral deflection control method for the work rolls of the 4- and 6-roll mills of the present invention;

[0025] In the diagram: 1: working roll, 2: support roll, 3: strip steel, 4: thrust device, 5: adjustment device, 6: bearing seat, 7: pressure sensor. Detailed Implementation

[0026] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills of the present invention includes the following steps:

[0028] S1. Calculate the rolling force and tension difference before and after rolling according to the rolling schedule.

[0029] S2. Calculate the roll eccentricity based on the front and rear tension difference of the strip and the rolling force value. The target is to make the lateral force on the roll body zero.

[0030] like Figure 1As shown, let: work roll radius r, support roll radius R, eccentricity e, rolling force F0, horizontal component of rolling force F2, strip front tension T0, strip rear tension T1, and other unstable factors Fx, such as: equipment processing accuracy, friction state between strip and roll, etc. These uncertainties need to be compensated for through testing. Then:

[0031] Let: F2 + T1 - T0 + Fx = 0

[0032] The calculation yields: .

[0033] S3. Adjust the horizontal position of the working roller so that the offset between the center line of the working roller and the support roller reaches the calculated value.

[0034] S4. Roll pressing down, strip tensioning, check the roll stress detected by the work roll bearing housing horizontal force detector. If the stress exceeds the set limit, open the adjusting roll gap to readjust the eccentricity. Feedback the deviation to the calculation library to correct the calculation formula.

[0035] S5. Rolling will begin when the roll body is under stress within the set range.

[0036] This invention's method is adaptable to rolling various specifications and steel grades, exhibiting greater adaptability to the rolling environment. It controls the lateral force on the roll body within a certain range, effectively reducing lateral deflection and achieving better strip shape. It allows for the use of smaller roll diameters in 4- and 6-roll mills. In strip rolling, a smaller work roll diameter requires less rolling force and torque, and less elastic flattening of the rolls. Therefore, small roll diameters are necessary for rolling high-strength strips. However, the lateral force on the rolls during rolling causes lateral deflection. Excessive deflection severely affects strip shape quality. The smaller the work roll diameter, the greater the deflection under lateral force. Therefore, the work roll diameter in 4- and 6-roll mills is severely limited by lateral deflection deformation; conventional wide strip 4- and 6-roll mills typically have work roll diameters exceeding 300mm. This method reduces the lateral force on the work rolls, allowing for the use of smaller work roll diameters.

[0037] like Figure 2 As shown, this is the equipment used in the lateral deflection control method of the work rolls in 4- and 6-roll mills. A positioning device is installed on the bearing seats on both sides of the work roll at the exit end, which can precisely adjust the horizontal position of the work roll within a certain range, with a positioning accuracy of 1 micrometer. A thrust device is installed at the inlet end, which contains a high-precision pressure sensor to accurately measure the thrust force, and is also equipped with a high-precision displacement sensor to measure the thrust position.

[0038] In this embodiment, the positioning device takes the form of a wedge adjusting block. Part of the wedge is fixed to the mill stand, while the other part is extended and retracted by a hydraulic cylinder, thereby achieving left-side positioning of the roll bearing seat. The thrust device is a pad pushed by a hydraulic cylinder, which is mounted on the right-side stand. When the roll advances into the stand, the hydraulic cylinder extends and presses against the right side of the work roll, firmly against the left-side positioning device. This adjusts and fixes the position of the work roll center relative to the stand center. The positioning device and thrust device are not limited to specific structures in this invention; this embodiment is merely a device design for implementing the method.

[0039] The present invention also provides a specific example as follows, including the following steps:

[0040] 1. Before rolling, calculate the required eccentricity e according to the rolling schedule, and calculate the stroke of the positioning device based on the eccentricity. The calculation formula is as follows:

[0041]

[0042] Assuming T0=300kN, T1=240kN, Fx=0kN, F0=8000kN, r=200mm, R=650mm, then the calculated value is e=6.375mm.

[0043] 2. The positioning device positions and locks the device.

[0044] 3. The hydraulic cylinder extends and outputs a large thrust, which is significantly greater than the horizontal force on the roller body, maintaining constant pressure. The pressure sensor can measure and record the horizontal pressure on the bearing housing. At this point, the calibrated work roller body experiences zero lateral horizontal force.

[0045] 4. Press down, build tension, and check the pressure change measured by the pressure sensor. This pressure change value is the lateral horizontal force on the roller body. Automatically detect whether it exceeds the set limit value.

[0046] 5. If the limit is exceeded, open the roll gap, revise the offset value, and correct the calculation formula. The correction process involves readjusting the roll eccentricity distance e and correcting the Fx value in the formula.

[0047] 6. Continue rolling until the roll body is under stress within the set range.

[0048] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for controlling the lateral deflection of work rolls in a 4- or 6-roll rolling mill, characterized in that, Includes the following steps: S1. Calculate the rolling force and tension difference between the front and rear sides according to the rolling schedule; S2. Calculate the roll eccentricity based on the front and rear tension difference of the strip and the rolling force value, with the target set to make the lateral force on the roll body zero. S3. Adjust the horizontal position of the working roller so that the offset between the center line of the working roller and the support roller reaches the calculated value; S4. Rolls are pressed down, strip is tensioned, and the roll stress detected by the horizontal force detector of the work roll bearing housing is checked. If the stress exceeds the set limit, the roll gap is opened and the eccentricity is corrected again. S5. Rolling starts when the working roll body is under stress within the set range.

2. The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills according to claim 1, characterized in that, In step S2, the eccentricity e is calculated using the following formula: Where r is the work roll radius, R is the support roll radius, F0 is the rolling force, F2 is the horizontal component of the rolling force, T0 is the strip front tension, T1 is the strip back tension, and Fx is the unstable factor.

3. The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills according to claim 1, characterized in that, Positioning devices are installed on the bearing seats on both sides of the work roll at the outlet end, and the positioning devices are used to adjust the horizontal position of the work roll.

4. The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills according to claim 3, characterized in that, The positioning device includes a wedge adjustment block, a part of which is fixed to the mill stand, and the other part is driven to extend and retract by a hydraulic cylinder to achieve left-side positioning of the roll bearing seat.

5. The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills according to claim 3, characterized in that, A thrust device is installed at the inlet end of the work roll, and a pressure sensor and a displacement sensor are installed inside the thrust device.

6. The method for controlling the lateral deflection of work rolls in 4- and 6-roll mills according to claim 5, characterized in that, The thrust-stopping device is a pad driven by a hydraulic cylinder. The hydraulic cylinder is installed on the right side of the archway. When the roll advances into the archway, the hydraulic cylinder extends and presses against the right side of the work roll, pressing the work roll tightly against the positioning device on the left side, thereby adjusting and fixing the position of the work roll center relative to the archway center.

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