Automatic correction control method for head and tail tracking of empty rack of thick plate

Abstract

The invention discloses an automatic correction control method for head and tail tracking of a thick plate passing through a rack, which comprises the following steps of: respectively taking steel biting and steel throwing signals of an inlet pinch roll and an outlet pinch roll as strip steel head and tail correction signals, and respectively acquiring strip steel head tracking distance values when the inlet pinch roll and the outlet pinch roll bite or throw steel during production; the method comprises the following steps of: respectively comparing two physical distance values with physical distance values of corresponding pinch rolls to obtain two error values, then calculating a deviation value, comparing the deviation value with a set P value to judge whether the tracking distance is normal or not, and normally operating a system when the tracking distance is normal; and if not, taking the physical distance value of the position of the outlet pinch roll as the actual tracking distance value of the head or the tail of the strip steel, and correcting. By judging the real-time change conditions of the position and the pressure in the process of biting and throwing the head and the tail of the strip steel, the abnormal strip steel head and tail tracking distance is automatically corrected, so that high-precision tracking can still be kept under the condition that a finish rolling mill is idle in the thick plate rolling process, and the finish rolling stability is ensured.

Description

Technical Field

[0001] This invention belongs to the field of thick plate rolling technology, specifically relating to an automatic correction control method for tracking the head and tail of a thick plate during empty pass through a mill stand. Background Technology

[0002] Currently, the finishing mill area of ​​the 2250 rolling line is equipped with seven consecutive rolling mills. Each mill is connected by a looper system to ensure stable strip roll volume and tension during continuous rolling. The loopers are equipped with angle encoders and pressure sensors to detect the actual strip roll volume and tension during rolling and transmit this data back to the primary control system for automatic control. The finishing mills, according to the secondary specifications, execute corresponding roll gap values ​​for each stand. By adjusting the roll gap distribution across each stand, the system ensures that the strip thickness at the finishing mill exit meets the finished product thickness requirements while maintaining equipment and on-site production stability.

[0003] Typically, the looper operation sequence is divided into three stages: looper lifting and tension establishment, looper stabilization control, and looper lowering. The looper lifting and lowering stages rely heavily on strip head-to-tail tracking to trigger the corresponding looper control. In continuous rolling, a seven-stand finishing mill is generally used. However, when rolling thick plates, because the required finishing mill reduction load is lower, typically one or two finishing mill stands are skipped during the rolling process. But due to the often high moisture content in the finishing mill, some photocell detectors in the finishing mill area may malfunction or flicker, causing errors in the tracking of the strip head-to-tail.

[0004] Currently, the common practice in the finishing mill area for strip head and tail tracking signals is for the product manager to organize relevant personnel to conduct pre-rolling confirmation during the rolling of thick plates. This includes checking the status of a series of photocell devices that affect tracking in the finishing mill area, and minimizing water vapor during rolling to avoid its influence. However, in actual production, significant water vapor interference with the photocell signals has repeatedly occurred, causing tracking errors. When this anomaly is detected in advance, the strip with the tracking error is pulled out of the finishing mill area and pushed into the intermediate billet for processing. If it is not detected in time, it can easily cause abnormalities in the rolling process control, and even lead to scrap steel accidents.

[0005] With existing tracking methods, tracking errors cannot be completely avoided. High humidity levels on-site are a major factor affecting phototube detection. When high humidity causes phototube flickering, tracking errors are highly likely, and there are no effective correction methods. Furthermore, when tracking errors occur, operators lack reasonable means to mitigate the potential risks. If detected promptly, the erroneous strip can be pulled out of the finishing rolling area and pushed into intermediate billets. However, if not detected in time, it can easily lead to abnormal looper control during rolling, or even scrapping accidents.

[0006] Other conventional hot rolling mills operate similarly, relying on operators to manually pull abnormally thick plates out of the finishing rolling area, push the intermediate billet, and continue production, which also presents the aforementioned problems. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic correction control method for the head and tail tracking of the strip during the no-load pass of the finishing mill. By judging the real-time changes in the gap between the pinch rolls and the pressure during the biting and throwing of the strip at the head and tail, the method automatically corrects the abnormal tracking distance of the strip head and tail, thereby achieving high-precision tracking even when the finishing mill is empty during the thick plate rolling process, and ensuring the stability of the finishing rolling.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: an automatic correction control method for tracking the head and tail of a thick plate passing through a frame, characterized by comprising the following steps: Real-time monitoring of the steel biting and throwing signals of the inlet and outlet pinch rollers of the descaling box; (2) Obtain the strip head tracking distance value when the inlet and outlet pinch rolls bite the strip respectively, and compare it with the physical distance value of the corresponding pinch rolls to obtain the first head error value D. t1 Second head error value D t2 Then calculate the head deviation value D. tp ;D tp =|D t1 -D t2 |;When the head deviation value D tp When the deviation is less than P, the current strip head tracking distance is considered normal, and the system is operating normally; when the head tracking deviation value is less than P, the current strip head tracking distance is considered normal, and the system is operating normally. tp When the value is ≥P, the current strip head tracking distance is determined to be abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip head tracking distance value and corrected accordingly. (3) Obtain the tracking distance value of the strip tail when throwing steel at the inlet and outlet pinch rolls respectively, and compare it with the physical distance value of the corresponding pinch rolls to obtain the first tail error value D. w1 Second tail error value D w2 Then calculate the tail tracking deviation value D. wp ;D wp =|D w1 -D w2 |;When the deviation value D wp When the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally; when the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally. wp If the actual tracking distance is ≥P, it is determined that the actual tracking distance is abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip tail tracking distance value and corrected accordingly.

[0009] Furthermore, when the pressure of the inlet pinch roll or outlet pinch roll is greater than the bite pressure setting value and the inlet jump roll gap value is greater than the bite roll gap setting value, a bite signal is generated; when the pressure of the inlet pinch roll or outlet pinch roll after bite is less than or equal to the throw pressure setting value and the inlet jump roll gap value is less than or equal to the throw roll gap setting value, a throw signal is generated.

[0010] Furthermore, before the strip enters the descaling box, the roll gap H between the inlet pinch roll and the outlet pinch roll of the descaling box is adjusted. r H C ; make H r =H C =H b -X, where H b Where X is the strip thickness, 1 < X < 2.5. Preferably, X = 2.

[0011] Furthermore, the tracking distance of the strip head is adjusted by using the exit speed of the pinch roll.

[0012] Furthermore, the selection of the strip tail tracking distance is corrected by multiplying the strip speed of the last stand by the back slip value.

[0013] The beneficial effects of the present invention are as follows: By using the above method, the real-time changes in position and pressure during the strip head and tail biting and throwing process can be judged. Without using photoelectric tubes to detect the strip head and tail, the tracking of the strip head and tail can be accurately corrected by the changes in the pressure of the pinch rolls and the roll gap position signal. This achieves high-precision tracking even when the finishing mill is idle during the thick plate rolling process, ensuring the stability of the finishing rolling. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0015] Figure 1 This is a flowchart illustrating the method of the present invention.

[0016] Figure 2 This is a schematic diagram of the process for correcting the tracking distance of the strip head in this invention.

[0017] Figure 3 This is a schematic diagram of the process for correcting the tracking distance at the tail of the strip in this invention.

[0018] Figure 4 A schematic diagram showing the state of the strip head preparing to enter the inlet pinch roll area.

[0019] Figure 5 This is a schematic diagram of the strip steel passing through the descaling box and then empty through the F6 stand in the finishing rolling area.

[0020] In the diagram, 10 is the inlet pinch roll; 20 is the outlet pinch roll; 30 is the thick strip steel; and F1-F7 are the seven stands corresponding to the finishing mill. Detailed Implementation

[0021] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] like Figure 1 As shown, an automatic correction control method for tracking the head and tail of a thick plate passing through a frame includes the following steps: Before the strip enters the descaling box, adjust the inlet and outlet pinch rollers of the descaling box to the waiting position. At this time, the gap between the inlet and outlet rollers is H. r H C ; make H r =H C =H b -X, where H b Where X is the strip thickness, 1 < X < 2.5. Within this roll gap range, slippage is prevented while indentation is avoided. Preferably, X is 2, which yields the best results.

[0023] During the production process, the steel biting and steel throwing signals of the inlet and outlet pinch rollers of the descaling box are monitored in real time.

[0024] (2) Strip head tracking correction: such as Figure 2 As shown, when the pressure of the inlet pinch roll is greater than the bite pressure set value (Xon kN) and the inlet jump roll gap value is greater than the bite roll gap set value (Yon mm), an inlet pinch roll bite signal is generated; the strip head tracking distance value when the inlet pinch roll bites is obtained and compared with the physical distance value of the inlet pinch roll to obtain the first head error value D. t1 As the strip is conveyed, when the pressure of the exit pinch roll is detected to be greater than the bite pressure set value (Xon kN) and the exit jump roll gap value is greater than the bite roll gap set value (Yon mm), an exit pinch roll bite signal is generated; the strip head tracking distance value at the exit pinch roll bite is obtained and compared with the physical distance value of the exit pinch roll to obtain the second head error value D. t2 .

[0025] Next, calculate the head deviation value D. tp ;D tp =|D t1 -Dt2 |;When the head deviation value D tp When the deviation is less than P, the current strip head tracking distance is considered normal, and the system is operating normally; when the head tracking deviation value is less than P, the current strip head tracking distance is considered normal, and the system is operating normally. tp When the value is ≥P, the current strip head tracking distance is determined to be abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip head tracking distance value, and the exit speed of the pinch roll is selected to correct the strip head tracking distance.

[0026] (3) Strip tail tracking correction: such as Figure 3 As shown, as the strip is conveyed, when the pressure of the inlet pinch roll after the strip bites is ≤ the set value of the strip throwing pressure (Xoff kN) and the inlet jump roll gap value is ≤ the set value of the strip throwing roll gap (Yoff mm), an inlet pinch roll strip throwing signal is generated; the tracking distance value of the strip tail when the inlet pinch roll throws the strip is obtained, and the difference is compared with the physical distance value of the inlet pinch roll to obtain the first tail error value D. w1 As the strip is conveyed, when the pressure of the exit pinch roll is ≤ the corresponding throwing pressure setting value (Xoff kN) and the exit jump roll gap value is ≤ the bite roll gap setting value (Yoff mm), an exit pinch roll bite signal is generated; the tracking distance of the strip tail when the exit pinch roll bites is obtained, and the difference is compared with the physical distance value of the exit pinch roll to obtain the second head error value D. w2 .

[0027] Next, calculate the tail tracking deviation value D. wp ;D wp =|D w1 -D w2 |;When the deviation value D wp When the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally; when the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally. wp When the value is ≥P, the actual tracking distance is determined to be abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip tail tracking distance value, and the strip tail tracking distance is corrected by multiplying the strip speed of the last stand by the back slip value.

[0028] Specifically, the physical distance value of the inlet pinch roller is a fixed value representing the zero-position tracking distance when the inlet pinch roller bites the steel; the physical distance value of the outlet pinch roller is also a fixed value representing the zero-position tracking distance when the outlet pinch roller bites the steel. Thus, by comparing the physical distance values ​​of the inlet and outlet pinch rollers with the system's tracking distance value, any tracking anomalies can be detected. P is a fixed value set according to the tracking accuracy of different plate thicknesses, used to compare with the deviation value to determine if any tracking anomalies exist.

[0029] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for automatic correction control of thick plate unloaded through machine frame head and tail tracking, characterized in that, Includes the following steps: Real-time monitoring of the steel biting and throwing signals of the inlet and outlet pinch rollers of the descaling box; The tracking distance values ​​of the strip head when the inlet and outlet pinch rolls bite the strip are obtained respectively, and the difference is compared with the physical distance value of the corresponding pinch roll to obtain the first head error value D. t1 Second head error value D t2 Then calculate the head deviation value D. tp ;D tp =|D t1 -D t2 |;When the head deviation value D tp If the distance is less than P, the current strip head tracking distance is considered normal, and the system is operating normally. When the head tracking deviation value D tp When the value is ≥P, the current strip head tracking distance is determined to be abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip head tracking distance value and corrected accordingly. The tracking distance of the strip tail during the throwing of steel by the inlet and outlet pinch rolls is obtained respectively, and the difference is compared with the physical distance value of the corresponding pinch roll to obtain the first tail error value D. w1 Second tail error value D w2 Then calculate the tail tracking deviation value D. wp ;D wp =|D w1 -D w2 |;When the deviation value D wp When the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally; when the deviation value is less than P, the current strip tracking distance is determined to be normal, and the system is operating normally. wp If the actual tracking distance is ≥P, it is determined that the actual tracking distance is abnormal. The physical distance value of the exit pinch roll position is taken as the actual strip tail tracking distance value and corrected accordingly.

2. The automatic correction control method for tracking the head and tail of a thick plate passing through a frame as described in claim 1, characterized in that, A steel biting signal is generated when the pressure of the inlet or outlet pinch roll is greater than the steel biting pressure setting value and the inlet jump roll gap value is greater than the steel biting roll gap setting value; a steel throwing signal is generated when the pressure of the inlet or outlet pinch roll after steel biting is less than or equal to the steel throwing pressure setting value and the inlet jump roll gap value is less than or equal to the steel throwing roll gap setting value.

3. The automatic correction control method for tracking the head and tail of a thick plate passing through a frame as described in claim 1, characterized in that, Before the strip enters the descaling box, adjust the gap H between the inlet and outlet pinch rollers of the descaling box. r H C ; make H r =H C =H b -X, where H b X represents the thickness of the strip, where 1mm < X < 2.5mm.

4. The automatic correction control method for tracking the head and tail of a thick plate passing through a frame as described in claim 3, characterized in that, X=2mm.

5. The automatic correction control method for tracking the head and tail of a thick plate passing through a frame according to any one of claims 1-4, characterized in that, The tracking distance of the strip head is corrected by using the exit speed of the pinch roll.

6. The automatic correction control method for tracking the head and tail of a thick plate passing through a frame according to any one of claims 1-4, characterized in that, The selection of the strip tail tracking distance is corrected by multiplying the strip speed of the last stand by the back slip value.

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