Method for searching reasons for increasing roll gap deviation of rolling mill

Abstract

The invention provides a method for searching for reasons for increasing roll gap deviation of a rolling mill, and relates to the technical field of rolling processes of the rolling mills. Firstly, before the rolling mill works, a working roll is periodically replaced according to the service cycle of the working roll, and a supporting roll is periodically replaced according to the service cycle of the supporting roll; attachments influencing the detection precision of the displacement sensor are cleaned to ensure the detection precision of the displacement sensor; secondly, the order number of a lower step pad used by the rack, the box number of a back-up roll bearing seat and a roll gap deviation value corresponding to the rack are recorded, and the roll gap deviation value corresponding to the rack is obtained through calculation of a detection value of a displacement sensor, so that historical data used for comparison are obtained; and finally, comparing the recorded current data with historical data to judge whether the roll gap deviation becomes large because of an arc-shaped pad or a lower step pad. Therefore, the problem that in the prior art, the reasons causing the roll gap deviation to become large cannot be effectively found out is solved, and the method is suitable for finding the reasons causing the roll gap deviation to become large of the rolling mill.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rolling mill rolling process, in particular to a method for finding out the reason for the large deviation of the rolling mill roll gap. BACKGROUND

[0002] The rolling mill generally comprises a plurality of stands, and each stand mainly comprises the following components: a balancing device, an upper step pad device, an AGC hydraulic cylinder, a backup roll, a work roll, a work roll balancing device, a lower step pad adjustment and a roll changing slide seat, etc. These devices are symmetrically installed in the rolling mill housing to form a rolling mill roll system, which is divided into an operation side and a transmission side according to the rolling direction. The main working principle is that the upper and lower work rolls are power rolls, and the upper and lower backup rolls are idler rolls; the work roll is driven to rotate by a motor through a speed reducer, and the backup roll is driven to rotate by the work roll while providing a supporting action. In the rolling process, the roll gap value is detected by displacement sensors installed on the AGC hydraulic cylinders on the operation side and the transmission side.

[0003] Due to the wear of the work roll and the backup roll caused by the rolling process, the work roll and the backup roll are replaced when the wear reaches a certain degree. In order to quickly replace the work roll and the backup roll, the upper step pad and the lower step pad are provided, the upper step pad generally has about 4 steps, and the lower step pad has about 12 steps, and the step pads are driven by hydraulic cylinders. In view of the wear of the backup roll and the work roll, different thicknesses of pressure equalizing plates are added to the upper backup roll bearing seat for position compensation, and arc-shaped pads are added to the lower backup roll bearing seat. Therefore, the lower step pad and the arc-shaped pad on the lower backup roll bearing are key points for bearing the load of the rolling mill.

[0004] After the work roll and the backup roll are replaced, the number of steps of the upper and lower step pads needs to be quickly adjusted to correspond to the change in the roll diameter, and the roll gap is eliminated (the gap is eliminated) by a certain load, and then the deviation value of the roll gap data detected by the displacement drive of the AGC hydraulic cylinder is checked to see whether it meets the set requirements, and the final calibration is completed.

[0005] In the rolling process, the wear of the work roll and the backup roll will cause the roll gap deviation to become larger and larger, so when the roll gap deviation is greater than a certain value (such as 1mm), it will cause the rolling to produce a wave shape or deviation, even scrap steel, etc., therefore, monitoring the roll gap deviation is beneficial to production.

[0006] The existing processing method is: 1, re-replace the work roll, according to the change of roll diameter, the use of step pad changes the step number, and the calibration may be successful; 2, after replacing the work roll continuously, the calibration still cannot pass, so the machine is stopped to check whether there is foreign matter on the step pad, and the calibration may pass after the foreign matter is removed; 3, after the above two steps are completed, the calibration still cannot be completed smoothly, so the passing deviation value is modified (enlarged), and the calibration is forced to pass to facilitate the resumption of production (there is a risk of unstable rolling state); the above processing method has the following defects: the deviation of the roll gap value on both sides is large, there is difference, the lower work roll is not horizontal, in order to ensure the consistency of the roll gap, the difference of the extension length of the AGC hydraulic cylinder on both sides is adjusted to meet the consistency of the roll gap, in fact, the whole roll gap of the rolling mill is inclined or still has a certain deviation, which causes the wave shape or deviation during rolling, even scrap steel and the like. This is a functional defect in the production process. It not only increases the instability of production, but also may produce a large amount of cutting loss and scrap steel, and even damage the equipment. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a rolling mill roll gap deviation finding method to solve the problem that the cause of the large roll gap deviation cannot be effectively found in the prior art.

[0008] The technical solution adopted by the present application to solve the above technical problem is: a rolling mill roll gap deviation large reason finding method, the rolling mill comprises a plurality of stands, and the method comprises the following steps: S1, before the rolling mill works, the work roll is replaced regularly according to the use period of the work roll, and the support roll is replaced regularly according to the use period of the support roll, and the attached matter affecting the detection accuracy of the displacement sensor is cleaned; S2, the step number of the lower step pad used by the stand, the bearing seat box number of the support roll and the roll gap deviation value corresponding to the stand are recorded, and the roll gap deviation value corresponding to the stand is obtained by calculating the detection value of the displacement sensor; S3, if the roll gap deviation value of the current stand is greater than a first preset value and less than a second preset value, a warning is given, and if the roll gap deviation value of the current stand is greater than the second preset value, S4 and S5 are entered; S4, the size of the roll gap deviation value of the current stand and the first historical roll gap deviation value are compared, the first historical roll gap deviation value is the roll gap deviation value corresponding to the same lower step pad and different support roll bearing seat box numbers used by the current stand, and if the roll gap deviation value of the current stand is greater than the first historical roll gap deviation value, the reason for the large roll gap deviation is the lower step pad; S5, compare the roll gap deviation value of the current stand with the second historical roll gap deviation value; the second historical roll gap deviation value is the roll gap deviation value corresponding to the different lower step pad and the same support roller bearing seat box number used by the current stand; if the roll gap deviation value of the current stand is greater than the second historical roll gap deviation value, the reason for the increase of the roll gap deviation is the arc-shaped pad.

[0009] Further, in S1, the service life of the work roll is 2800 tons of rolling.

[0010] Further, in S1, the service life of the support roll is 300,000 tons of rolling.

[0011] Further, in S1, the attachment includes the oxidized dust and the oil sludge on the pressure plate of the upper support roll bearing seat and the arc-shaped pad of the lower support roll bearing seat.

[0012] Further, in S2, the calculation formula of the roll gap deviation value is: , wherein, represents the roll gap deviation value, represents the detection data of the displacement sensor on the operation side inlet, represents the detection data of the displacement sensor on the operation side outlet, represents the detection data of the displacement sensor on the driving side inlet, represents the detection data of the displacement sensor on the driving side outlet.

[0013] Further, in S3, the first preset value is 1mm, and the second preset value is 1.5mm.

[0014] The present application provides a method for finding the reason for the increase of the roll gap deviation of the rolling mill, which first regularly replaces the work roll according to the service life of the work roll before the rolling mill works, and regularly replaces the support roll according to the service life of the support roll, and cleans the attachment affecting the detection accuracy of the displacement sensor to ensure the detection accuracy of the displacement sensor; secondly, records the step number of the lower step pad used by the stand and the bearing seat box number of the support roll and the roll gap deviation value corresponding to the stand, and the roll gap deviation value corresponding to the stand is obtained by calculating the detection value of the displacement sensor, so as to obtain the historical data for comparison; finally, based on the comparison between the recorded current data and the historical data, it is judged whether the reason for the increase of the roll gap deviation is the arc-shaped pad or the lower step pad. In this way, the problem that the reason for the increase of the roll gap deviation cannot be effectively found in the prior art is solved, which is beneficial to quickly finding the reason for the increase of the roll gap deviation, so as to correct in time during rolling and ensure the rolling quality. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a flowchart of a method for finding the reason for the increase of the roll gap deviation of the rolling mill provided by the present application. DETAILED DESCRIPTION

[0016] The present invention aims to solve the problem that the prior art cannot effectively find the cause of the larger roll gap deviation, and provides a method for finding the cause of the larger roll gap deviation of a rolling mill, wherein the rolling mill includes multiple sets of stands, and the method is as follows: Figure 1 As shown, the following steps are included:

[0017] S1. Before the rolling mill is put into operation, the working rolls should be replaced regularly according to the service life of the working rolls, and the support rolls should be replaced regularly according to the service life of the support rolls, and attachments that affect the detection accuracy of the displacement sensor should be cleaned.

[0018] Specifically, for a particular rolling mill, the working rolls used in each stand have a service life of 2,800 tons, and the backup rolls have a service life of 300,000 tons. The deposits include oxidized dust and oil sludge on the equalizing plate on the upper backup roll bearing seat and the curved pad on the lower backup roll bearing seat. Cleaning these deposits ensures the detection accuracy of the displacement sensor and reduces errors in the subsequent roll gap deviation calculation results.

[0019] S2. Record the number of steps of the lower step pad used by the frame, the box number of the support roller bearing seat, and the roll gap deviation value corresponding to the frame, where the roll gap deviation value corresponding to the frame is calculated based on the detection value of the displacement sensor.

[0020] Specifically, the calculation formula of the roll gap deviation value is: ,in, Indicates the roller gap deviation value, Indicates the displacement sensor detection data at the operating side entrance, Indicates the displacement sensor detection data of the operating side outlet, Represents the displacement sensor detection data of the first transmission side inlet, Indicates the displacement sensor detection data of the transmission side outlet.

[0021] For example, the displacement sensor detection data of the operating side entrance of a certain group of stands of a certain rolling mill The displacement sensor detection data of the operating side outlet is 34.66 mm. The displacement sensor detection data of the transmission side entrance is 34.98 mm. The displacement sensor detection data of the transmission side outlet is 33.64 mm. is 33.03 mm, so the roller gap deviation is 1.485 mm.

[0022] By recording the number of lower step pads used by the frame, the box number of the support roller bearing seat, and the roll gap deviation value corresponding to the frame, historical data for comparison is formed to prepare for subsequent judgment of the cause of the increase in roll gap deviation.

[0023] S3, if the roll gap deviation value of the current stand is greater than the first preset value and less than the second preset value, a pre-warning is performed, if the roll gap deviation value of the current stand is greater than the second preset value, S4 and S5 are entered.

[0024] Specifically, according to historical rolling experience, it is obtained that when the roll gap deviation value is below 1.0 mm, the rolling state is good, the production is very smooth, the product quality is stable, and the state is normal when rolling different kinds of steel; when the roll gap deviation value is between 1.0 mm and 1.5 mm, the rolling state is unstable, and the product quality is not easy to control, for example, the single-sided wave shape, the middle wave shape and the double-sided wave shape are prone to occur on the rolled strip, and the product requirements cannot be easily met by operation adjustment, therefore, the state is in the wear alarm state; when the roll gap deviation value is above 1.5 mm, the rolling state is very unstable, and the scrap steel is prone to be produced. Therefore, the production can be normally performed before the roll gap deviation value reaches 1.0 mm, the pre-warning is performed when the roll gap deviation value is greater than 1.0 mm and less than 1.5 mm, and the machine needs to be stopped for detection when the roll gap deviation value is greater than 1.5 mm, so that the reason for the increase of the roll gap deviation value is found, therefore, the first preset value is 1 mm, and the second preset value is 1.5 mm.

[0025] S4, the roll gap deviation value of the current stand is compared 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 step-down pad and different support roll bearing box numbers used by the current stand, if the roll gap deviation value of the current stand is greater than the first historical roll gap deviation value, the reason for the increase of the roll gap deviation value is the step-down pad.

[0026] Specifically, the roll gap deviation value of a certain stand is 1.6 mm, the step-down pad used by the stand has a step number of 5, and the support roll bearing box number is C2-3, since 1.6 mm is greater than 1.5 mm, the roll gap deviation value corresponding to the step-down pad with the step number of 5 and the support roll bearing box number not being C2-3 used by the stand is found in the historical record as the first historical roll gap deviation value, if the roll gap deviation value of the current stand is greater than the first historical roll gap deviation value, the reason for the increase of the roll gap deviation value is the step-down pad. The reason is that the step number of the step-down pad is unchanged, and the box number of the support roll is changed, so that the roll gap deviation value is increased, which indicates that the reason for the increase of the roll gap deviation value is the step-down pad.

[0027] S5, the roll gap deviation value of the current stand is compared with the second historical roll gap deviation value, the second historical roll gap deviation value is the roll gap deviation value corresponding to different step-down pads and the same support roll bearing box number used by the current stand, if the roll gap deviation value of the current stand is greater than the second historical roll gap deviation value, the reason for the increase of the roll gap deviation value is the arc-shaped pad.

[0028] Specifically, the roll gap deviation value of a certain stand is 1.55 mm, the step number of the lower step pad used by the stand is 5, and the support roll bearing seat box number is C2-3. Since 1.6 mm is greater than 1.5 mm, the roll gap deviation value corresponding to the step pad step number not being 5 and the support roll bearing seat box number being C2-3 used by the stand is searched in the historical record as a second historical roll gap deviation value. If the roll gap deviation value of the current stand is greater than the second historical roll gap deviation value, the reason for the increase in the roll gap deviation is the arc-shaped pad. The reason is that, under the condition that the support roll box number remains unchanged, the step number of the lower step pad changes, resulting in an increase in the roll gap deviation value, which indicates that the reason for the increase in the roll gap deviation is the arc-shaped pad.

Claims

1. A method for finding the cause of the larger roll gap deviation of a rolling mill, wherein the rolling mill comprises multiple sets of stands, each set of stands comprising working rolls, support rolls, lower step pads and arc pads, characterized in that: The method comprises the following steps: S1. Before the rolling mill is put into operation, the working rolls should be replaced regularly according to their service life, and the backup rolls should be replaced regularly according to their service life, and attachments that affect the detection accuracy of the displacement sensor should be cleaned; S2. Record the number of steps of the lower step pad used by the frame, the box number of the support roller bearing seat, and the roll gap deviation value corresponding to the frame, where the roll gap deviation value corresponding to the frame is calculated using 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 is issued. If the roll gap deviation value of the current frame is greater than the second preset value, the process proceeds to S4 and S5. S4. Compare the roll gap deviation value of the current stand with a first historical roll gap deviation value, where the first historical roll gap deviation value is a roll gap deviation value corresponding to a case where the current stand uses the same lower step pad and a different support roll bearing housing number. If the roll gap deviation value of the current stand is greater than the first historical roll gap deviation value, the increased roll gap deviation is caused by the lower step pad. S5. Compare the roll gap deviation value of the current stand 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 roll bearing seat box number used in the current stand; if the roll gap deviation value of the current stand 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 for finding the cause of the larger roll gap deviation of a rolling mill according to claim 1, characterized in that: In S1, the service life of the working roll is 2800 tons of rolling.

3. The method for finding the cause of the larger roll gap deviation of 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 for finding the cause of the larger roll gap deviation of a rolling mill according to claim 1, characterized in that: In S1, the attachments include oxidized dust and oil sludge located on the equalizing plate on the upper support roller bearing seat and the arc pad on the lower support roller bearing seat.

5. The method for finding the cause of the increased roll gap deviation of a rolling mill according to claim 1, characterized in that: In S2, the calculation formula of the roll gap deviation value is: ,in, Indicates the roller gap deviation value, Indicates the displacement sensor detection data at the operating side entrance, Indicates the displacement sensor detection data of the operating side outlet, Indicates the displacement sensor detection data at the transmission side entrance, Indicates the displacement sensor detection data of the transmission side outlet.

6. The method for finding the cause of the increased roll gap deviation of a rolling mill 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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