Method for finding out reason of increasing deviation of rolling mill roll gap

Abstract

This invention provides a method for finding the cause of increased roll gap deviation in rolling mills, relating to the field of rolling mill process technology. First, before the rolling mill begins operation, the work rolls are replaced periodically according to their service life, and the support rolls are replaced periodically according to their service life. Adhesives affecting the detection accuracy of displacement sensors are cleaned to ensure the accuracy of the sensors. Second, the step number of the lower stepped pad used on the stand, the support roll bearing housing number, and the corresponding roll gap deviation value for the stand are recorded. The roll gap deviation value for the stand is calculated from the displacement sensor detection value, thus obtaining historical data for comparison. Finally, based on the comparison between the recorded current data and the historical data, it is determined whether the increased roll gap deviation is caused by the curved pad or the lower stepped pad. This solves the problem in existing technologies where the cause of increased roll gap deviation cannot be effectively found. This invention is applicable to finding the cause of increased roll gap deviation in rolling mills.

Description

Technical Field

[0001] This invention relates to the field of rolling mill technology, and in particular to a method for finding the cause of increased roll gap deviation in rolling mills. Background Technology

[0002] A rolling mill typically consists of multiple stands, each primarily comprising: a balancing device, an upper stepped pad device, an AGC hydraulic cylinder, support rolls, work rolls, a work roll balancing device, a lower stepped pad adjustment mechanism, and roll changing slides. These devices are installed symmetrically within the mill stand, forming a rolling mill roll system, divided into an operating side and a drive side according to the rolling direction. Its main working principle is as follows: the upper and lower work rolls are powered rolls, while the upper and lower support rolls are idler rolls; the work rolls rotate via a motor and reducer, while the support rolls are driven by the work rolls, providing support. During the rolling process, displacement sensors mounted on the AGC hydraulic cylinders on both the operating and drive sides detect the roll gap value.

[0003] Because the rolling process causes wear on the work rolls and support rolls, they need to be replaced when the wear reaches a certain level. To facilitate rapid replacement, upper and lower stepped pads are installed. The upper stepped pad typically has about four steps, while the lower stepped pad has about twelve steps. The movement of these stepped pads is driven by hydraulic cylinders. Considering the wear on the support rolls and work rolls, pressure-equalizing plates of varying thicknesses are added to the upper support roll bearing housing for position compensation, and arc-shaped pads are added to the lower support roll bearing housing. Therefore, the lower stepped pads and the arc-shaped pads on the lower support roll bearings are key load-bearing points for the rolling mill.

[0004] After replacing the work roll and support roll, due to the change in the diameter of the work roll and support roll, it is necessary to quickly adjust the number of steps of the upper and lower step pads to correspond to the change in roll diameter. Then, a certain load is applied to press against the rollers (to eliminate gaps), and the deviation value of the roll gap data is detected by the displacement actuator of the AGC hydraulic cylinder to check whether it meets the set requirements, thus completing the final calibration.

[0005] During the rolling process, the wear of the work rolls and support rolls will cause the roll gap deviation to become larger and larger. Therefore, when the roll gap deviation exceeds a certain value (such as 1 mm), it will cause waviness or deviation during rolling, or even scrap steel. Therefore, monitoring the roll gap deviation is beneficial to production.

[0006] When encountering a roll gap deviation exceeding a certain value (e.g., 1 mm), the existing methods are: 1. Replace the work rolls. Depending on the roll diameter, the step size of the step pad changes, potentially leading to successful calibration; 2. If calibration still fails after consecutive work roll replacements, stop the machine and check for foreign objects on the step pad. Removing these objects may resolve the issue; 3. If calibration still fails after the above two steps, modify the acceptable deviation value (enlarge it) and force calibration to resume production (this carries the risk of unstable rolling conditions). These methods have the following drawbacks: large and inconsistent roll gap values ​​on both sides cause the lower work roll to be non-level. To ensure roll gap consistency, the difference in the extension length of the AGC hydraulic cylinders on both sides is adjusted. However, the entire roll gap of the mill is actually tilted or still has a certain deviation, leading to waviness or deviation during rolling, and even scrap. This is a functional defect in the production process. It increases production instability, potentially generating significant cutting losses and scrap, and even damaging equipment. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for finding the roll gap deviation of a rolling mill, so as to solve the problem that the existing technology cannot effectively find the cause of the roll gap deviation from increasing.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problem is: a method for finding the cause of increased roll gap deviation in rolling mills, wherein the rolling mill includes multiple stands, and the method includes the following steps:

[0009] S1. Before the rolling mill starts working, replace the work rolls regularly according to their service life, and replace the support rolls regularly according to their service life, and clean any attachments that may affect the detection accuracy of the displacement sensor.

[0010] S2. Record the step number of the lower step pad used in the frame, the bearing housing number of the support roller, and the corresponding roller gap deviation value of the frame. The roller gap deviation value of the frame is calculated by the detection value of the displacement sensor.

[0011] S3. If the roll gap deviation value of the current frame is greater than the first preset value and less than the second preset value, an early warning will be issued. If the roll gap deviation value of the current frame is greater than the second preset value, proceed to S4 and S5.

[0012] S4. Compare the current roll gap deviation value with the first historical roll gap deviation value. The first historical roll gap deviation value is the roll gap deviation value corresponding to the same lower step pad and different support roller bearing housing number when the current frame uses the same lower step pad. If the roll gap deviation value of the current frame is greater than the first historical roll gap deviation value, the reason for the increased roll gap deviation is the lower step pad.

[0013] S5. Compare the current roll gap deviation value with the second historical roll gap deviation value; the second historical roll gap deviation value is the roll gap deviation value corresponding to different lower step pads and the same support roller bearing housing number used in the current frame; if the roll gap deviation value of the current frame is greater than the second historical roll gap deviation value, the reason for the increased roll gap deviation is the arc pad.

[0014] Furthermore, in S1, the service life of the work roll is 2800 tons of rolling.

[0015] Furthermore, in S1, the service life of the support roller is 300,000 tons of rolling.

[0016] Furthermore, in S1, the deposits include oxidized dust and sludge located on the equalizing plate on the upper support roller bearing seat and the arc-shaped pad on the lower support roller bearing seat.

[0017] Furthermore, in S2, the formula for calculating the roll gap deviation value is: ,in, This indicates the roll gap deviation value. This represents the displacement sensor detection data at the operating side inlet. This indicates the displacement sensor detection data at the operator-side outlet. This represents the displacement sensor detection data at the transmission side inlet. This represents the displacement sensor detection data at the transmission side outlet.

[0018] Furthermore, in S3, the first preset value is 1 mm, and the second preset value is 1.5 mm.

[0019] The beneficial effects of this invention are as follows: This invention provides a method for finding the cause of increased roll gap deviation in rolling mills. First, before the rolling mill starts operation, the work rolls are replaced periodically according to their service life, and the support rolls are replaced periodically according to their service life. Adhesives affecting the detection accuracy of displacement sensors are cleaned to ensure the accuracy of the displacement sensors. Second, the step number of the lower stepped pad used in the mill stand, the bearing housing number of the support rolls, and the corresponding roll gap deviation value of the mill stand are recorded. The roll gap deviation value corresponding to the mill stand is calculated from the displacement sensor detection value, thus obtaining historical data for comparison. Finally, based on the comparison between the recorded current data and the historical data, it is determined whether the increased roll gap deviation is caused by the curved pad or the lower stepped pad. This solves the problem in the prior art of not being able to effectively find the cause of increased roll gap deviation, facilitating the rapid identification of the cause and timely correction during rolling to ensure rolling quality. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for finding the cause of increased roll gap deviation in a rolling mill, provided by the present invention. Detailed Implementation

[0021] This invention addresses the problem in existing technologies that cannot effectively identify the causes of increased roll gap deviation by providing a method for finding the causes of increased roll gap deviation in rolling mills. The rolling mill includes multiple stands. The method, as follows... Figure 1 As shown, it includes the following steps:

[0022] S1. Before the rolling mill starts operation, replace the work rolls regularly according to their service life, and replace the support rolls regularly according to their service life, and clean any attachments that may affect the detection accuracy of the displacement sensor.

[0023] Specifically, for a given rolling mill, the service life of the work rolls used in each stand is 2800 tons, and the service life of the support rolls is 300,000 tons. The deposits include oxidized dust and sludge on the equalizing plate on the upper support roll bearing seat and the arc-shaped pad on the lower support roll bearing seat. Cleaning these deposits ensures the accuracy of the displacement sensor and reduces errors in the subsequent calculation of the roll gap deviation.

[0024] S2. Record the step number of the lower step pad used in the frame, the bearing housing number of the support roller, and the roll gap deviation value corresponding to the frame. The roll gap deviation value corresponding to the frame is calculated by the detection value of the displacement sensor.

[0025] Specifically, the formula for calculating the roll gap deviation is as follows: ,in, This indicates the roll gap deviation value. This represents the displacement sensor detection data at the operating side inlet. This indicates the displacement sensor detection data at the operator-side outlet. This represents the displacement sensor detection data at the first transmission side inlet. This represents the displacement sensor detection data at the transmission side outlet.

[0026] For example, displacement sensor data detected at the operator side entrance of a certain stand in a rolling mill. The displacement sensor data at the operating side outlet is 34.66 mm. The displacement sensor data at the drive-side inlet is 34.98 mm. The displacement sensor data at the transmission side outlet is 33.64 mm. If the gap is 33.03 mm, then the roll gap deviation is 1.485 mm.

[0027] By recording the step number of the lower step pad used on the frame, the support roller bearing housing number, and the corresponding roll gap deviation value of the frame, historical data is generated for comparison, preparing for subsequent determination of the cause of the increased roll gap deviation.

[0028] S3. If the roll gap deviation value of the current frame is greater than the first preset value and less than the second preset value, an early warning will be issued. If the roll gap deviation value of the current frame is greater than the second preset value, proceed to S4 and S5.

[0029] Specifically, based on historical rolling experience: when the roll gap deviation is below 1.0 mm, the rolling condition is good, production is smooth, and product quality is stable, indicating a normal state. When the roll gap deviation is between 1.0 mm and 1.5 mm, the rolling condition is unstable, and product quality is difficult to control. For example, the strip is prone to single-sided waviness, middle waviness, and double-sided waviness, which are difficult to achieve the required product condition through operation and adjustment, thus triggering a wear alarm. When the roll gap deviation is above 1.5 mm, the rolling mill condition is very unstable, and scrap steel is easily generated. Therefore, production can proceed normally before the roll gap deviation reaches 1.0 mm. An early warning is issued when the roll gap deviation is greater than 1.0 mm but less than 1.5 mm. When the roll gap deviation is greater than 1.5 mm, the machine needs to be stopped for inspection to find the cause of the increased roll gap deviation. Therefore, the first preset value is 1 mm, and the second preset value is 1.5 mm.

[0030] S4. Compare the current roll gap deviation value with the first historical roll gap deviation value. The first historical roll gap deviation value is the roll gap deviation value corresponding to the same lower step pad and different support roller bearing housing number when the current frame uses the same lower step pad. If the roll gap deviation value of the current frame is greater than the first historical roll gap deviation value, the reason for the increased roll gap deviation is the lower step pad.

[0031] Specifically, the roll gap deviation of a certain frame is 1.6 mm. This frame uses a step 5 lower step pad, and the support roller bearing housing number is C2-3. Since 1.6 mm is greater than 1.5 mm, the historical roll gap deviation value corresponding to a step 5 lower step pad and a support roller bearing housing number other than C2-3 is searched for and taken as the first historical roll gap deviation value. If the current roll gap deviation value of the frame is greater than the first historical roll gap deviation value, then the reason for the increased roll gap deviation is the lower step pad. The reason is: when the step of the lower step pad remains unchanged, but the housing number of the support roller changes, resulting in a larger roll gap deviation value, it indicates that the increased roll gap deviation is caused by the lower step pad.

[0032] S5. Compare the current roll gap deviation value with the second historical roll gap deviation value; the second historical roll gap deviation value is the roll gap deviation value corresponding to different lower step pads and the same support roller bearing housing number used in the current frame; if the roll gap deviation value of the current frame is greater than the second historical roll gap deviation value, the reason for the increased roll gap deviation is the arc pad.

[0033] Specifically, the roll gap deviation of a certain frame is 1.55 mm. This frame uses a lower stepped pad with a step number of 5, and the support roller bearing housing number is C2-3. Since 1.6 mm is greater than 1.5 mm, the historical roll gap deviation value corresponding to a step number other than 5 for the stepped pad and a support roller bearing housing number of C2-3 is searched for and used as the second historical roll gap deviation value. If the current frame's roll gap deviation value is greater than the second historical roll gap deviation value, then the reason for the increased roll gap deviation is the curved pad. The reason is: with the support roller housing number remaining unchanged, the change in the step number of the lower stepped pad leads to an increased roll gap deviation value, indicating that the increased roll gap deviation is caused by the curved pad.

Claims

1. A method for finding the cause of increased roll gap deviation in a rolling mill, wherein the rolling mill includes multiple sets of stands, each set of stands includes work rolls, support rolls, lower step pads, and arc-shaped pads, characterized in that, The method includes the following steps: S1. Before the rolling mill starts working, replace the work rolls regularly according to their service life, and replace the support rolls regularly according to their service life, and clean any attachments that may affect the detection accuracy of the displacement sensor. S2. Record the step number of the lower step pad used in the frame, the bearing housing number of the support roller, and the corresponding roller gap deviation value of the frame. The roller gap deviation value of the frame is calculated by the detection value of the displacement sensor. S3. If the roll gap deviation value of the current frame is greater than the first preset value and less than the second preset value, an early warning will be issued. If the roll gap deviation value of the current frame is greater than the second preset value, proceed to S4 and S5. S4. Compare the current roll gap deviation value with the first historical roll gap deviation value. The first historical roll gap deviation value is the roll gap deviation value corresponding to the same lower step pad and different support roller bearing housing number when the current frame uses the same lower step pad. If the roll gap deviation value of the current frame is greater than the first historical roll gap deviation value, the reason for the increased roll gap deviation is the lower step pad. S5. Compare the current roll gap deviation value with the second historical roll gap deviation value; the second historical roll gap deviation value is the roll gap deviation value corresponding to different lower step pads and the same support roller bearing housing number used in the current frame; if the roll gap deviation value of the current frame is greater than the second historical roll gap deviation value, the reason for the increased roll gap deviation is the arc pad.

2. The method according to claim 1, characterized in that, In S1, the service life of the work roll is 2800 tons of rolling.

3. The method for finding the cause of increased roll gap deviation in a rolling mill according to claim 1, characterized in that, In S1, the service life of the support roller is 300,000 tons of rolling.

4. The method of claim 1, wherein the method is characterized by: In S1, the attached material includes oxidized dust and sludge located on the equalizing plate on the upper support roller bearing seat and the arc-shaped pad on the lower support roller bearing seat.

5. The method according to claim 1, characterized in that, In S2, the formula for calculating the roll gap deviation is: ,in, Indicates the roll gap deviation value. This represents the displacement sensor detection data at the operating side inlet. This indicates the displacement sensor detection data at the operator-side outlet. This represents the displacement sensor detection data at the transmission side inlet. This represents the displacement sensor detection data at the transmission side outlet.

6. The method according to claim 1, characterized in that, In S3, the first preset value is 1 mm and the second preset value is 1.5 mm.

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