A method for identifying and determining and controlling abnormal cross roll action of a PC rolling mill

Abstract

The application discloses a kind of identification determination and control method based on PC rolling mill cross roller action abnormality, after motor starts, by real-time monitoring and determination to motor speed and real-time monitoring and determination to torque current, the determination identification and control of cross roller action abnormality are completed.A kind of identification determination and control method based on PC rolling mill cross roller action abnormality of the application can realize the early determination of cross roller jam, can provide planned arrangement space for the specific processing of jam cross roller in later period, so as to reduce the shutdown cost.

Description

Technical Field

[0001] This invention belongs to the field of automatic control of metallurgical rolling mill, and specifically relates to a method for identifying, judging and controlling abnormal movement of cross rolls in PC rolling mills. Background Technology

[0002] In current operations, the method of determining whether the cross rollers are jammed is the limit signal method. This is a post-event judgment method, meaning that the out-of-position signal is only generated after actual jamming occurs. At this time, corresponding post-event handling is required based on the occurrence of the accident, including stopping the machine for replacement, temporary on-site matching, etc., which results in a huge waste of handling costs.

[0003] The invention application with application number CN201410010253.7 discloses "a method for detecting the rolling force of a computer-controlled rolling mill stand in hot continuous rolling", which includes the following steps: obtaining the rolling force under hydraulic pressure; inputting the rolling force detected by the pressure measuring head; detecting the static deviation under different pressure measuring methods; detecting the dynamic deviation under different measurement methods; detecting the deviation of the rolling force at different PC angles; and compensating for the deviation of the hydraulic rolling force.

[0004] The invention application with application number CN201610044456.7 discloses "an online monitoring method for the cross accuracy of a PC rolling mill cross roll system", which includes the following steps: collecting the static pressure oil column deviation and the turntable oil column deviation of each stand; calculating and judging whether the cross accuracy of the stand exceeds the limit by judging the oil column deviation of the stand, so as to realize the evaluation of the cross accuracy of the rolling mill cross roll system.

[0005] The invention application with application number CN202110864490.X discloses "a method for characterizing the degree of crossover of the roll system in a hot rolling mill". The method monitors the gap of the mill stand during the zero adjustment process, performs dynamic pressing in stages, obtains the bearing return oil temperature formula through linear fitting, calculates the return oil temperature of the mill support bearing under working conditions, and then obtains the lateral expansion of the bearing. The gap values ​​are then compared. When it is found that the dynamic gap of the mill support roll does not meet the standard requirements, the machine is stopped and the gap is readjusted.

[0006] The invention application with application number CN202111536399.1 discloses "a method for pre-judging overload of a hot rolling mill roll motor". The method includes: setting a current sampling time in advance; periodically sampling the current data of the roll motor of each rolling mill unit in the hot rolling mill within the preset current sampling time; calculating the maximum overload rate of the hot rolling mill roll motor within the current sampling time; determining whether the maximum overload rate is less than the overload rate judgment threshold; determining whether the computer-set rolling force for the next piece of steel is less than the overload rolling force judgment threshold; if the maximum overload rate is greater than the overload rate judgment threshold and the computer-set rolling force is greater than the overload rolling force judgment threshold, then it is determined that the hot rolling mill roll motor will be overloaded. Summary of the Invention

[0007] The purpose of this invention is to provide a solution that can pre-determine cross roller jamming, so that maintenance can be planned and thus reduce downtime costs.

[0008] To achieve the above technical objectives, this invention provides a method for identifying, judging, and controlling abnormal movement of cross rolls in a PC rolling mill, the specific technical solution of which is as follows:

[0009] A method for identifying, judging, and controlling abnormal movement of cross rolls in a PC rolling mill.

[0010] After the motor starts, by monitoring and judging the motor speed in real time, and by monitoring and judging the torque current in real time, the abnormal movement of the cross rollers can be identified and controlled.

[0011] Furthermore,

[0012] The aforementioned determination, identification, and control specifically include the following steps:

[0013] S1: Real-time acquisition of motor feedback speed and comparison with given speed. When the difference between the given speed and the motor feedback speed is greater than or equal to the set threshold, the first alarm is triggered and the process proceeds to step S3; otherwise, monitoring continues.

[0014] S2: According to the set cycle, the torque current is collected in real time within the set time period, and the abnormal movement of the cross roller is identified based on the data processing results of each torque current within the collection time period. When the data processing result is greater than or equal to the set threshold, the second alarm is triggered and the process proceeds to step S3; otherwise, monitoring continues.

[0015] S3: Determine the alarm category. If it is only the first alarm, or if the first alarm and the second alarm occur simultaneously, count the number of first alarms and notify the corresponding PC mill cross roll control processing based on the number of first alarms. If it is only the second alarm, notify the planned processing arrangement.

[0016] Furthermore,

[0017] Step S2, "identifying and determining abnormal cross roller operation based on the data processing results of each torque current within the acquisition time," includes:

[0018] Based on the calculation results of the average torque current during the collection period, the abnormal movement of the cross rollers is identified and judged.

[0019] And based on the variance calculation results of each torque current within the acquisition time, the abnormal operation of the cross roller is identified.

[0020] Furthermore,

[0021] When identifying abnormal cross roller operation based on the average torque current calculation within the acquisition period, the threshold used for comparison with the average calculation result is determined according to the following formula:

[0022] α=x UF +Δ α ,

[0023] In the above formula,

[0024] α: A set threshold for comparison with the mean calculation result, in percentage of the motor's rated current;

[0025] x UF Upper limit torque current, unit: percentage of motor rated current;

[0026] Δ α Compensation value, percentage of the motor's rated current.

[0027] Furthermore,

[0028] The corresponding compensation values ​​are set separately for four states: motor forward start, motor reverse start, no-load, and load.

[0029] When the motor is in forward rotation starting state, the compensation value is determined according to 20%;

[0030] When the motor is in reverse starting state, the compensation value is determined according to 50%;

[0031] When under no-load or load conditions, the compensation value is determined according to 0%.

[0032] Furthermore,

[0033] The clutch operation determines whether the motor is under no-load or load.

[0034] Furthermore,

[0035] When the abnormal operation of the cross roller is identified based on the variance calculation results of each torque current within the collection period, the threshold used for comparison with the variance calculation results is set separately according to the two states of no-load and load.

[0036] When the system is unloaded, the threshold value is set and determined within the range [0.05, 0.1] based on the actual situation.

[0037] When under load, the threshold is set and the value is determined within the range [0.1, 0.5] based on the actual situation.

[0038] Furthermore,

[0039] The aforementioned judgment, identification, and control of abnormal cross roll movement is performed on each stand. Specifically, step S3, "controlling the corresponding PC mill cross rolls based on the number of first alarms," ​​involves:

[0040] If the number of alarms exceeds the set limit, the PC angle adjustment function for the current mill will be locked. Operators will then adjust the PC angles of the remaining mills according to the actual situation.

[0041] This invention discloses a method for identifying and controlling abnormal movement of cross rolls in a PC rolling mill. By establishing real-time monitoring and judgment of motor speed in conjunction with real-time monitoring and judgment of torque current, the method identifies and controls abnormal movement of the cross rolls. The real-time monitoring and judgment of torque current allows for advance prediction and identification of whether the cross rolls are jammed, enabling pre-planning of handling when jamming occurs and reducing downtime costs. The real-time monitoring and judgment of motor speed serves as a double-insurance setting for abnormality identification and judgment, compensating for and creating a bottom-line monitoring limit due to gaps in the monitoring of torque current cycles; it is a safety-insurance feature. In the specific process of identifying and judging anomalies based on torque current, specific identification and judgment methods are established from both horizontal and vertical dimensions. This allows for comprehensive monitoring and identification of different types of jamming in various situations. The so-called vertical identification and judgment refers to the identification and judgment based on mean calculation and the identification and judgment based on variance calculation mentioned in the text. These two methods can be used to identify different types of jamming. The so-called horizontal identification and judgment refers to the setting of corresponding thresholds based on various working states, as mentioned in the text, so that the judgment is in line with the actual situation.

[0042] The present invention provides a method for identifying and controlling abnormal movement of cross rolls in PC rolling mills. This method can determine cross roll jamming in advance, providing a planned arrangement for subsequent specific handling of jammed cross rolls, thereby reducing downtime costs. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the determination, identification, and control steps of the present invention;

[0044] Figure 2 This is a schematic diagram of the cross roller cross angle swing structure in the working principle and process of the present invention;

[0045] Figure 3 According to Figure 2 A schematic diagram of the operation of a cross rolling mill. Detailed Implementation

[0046] The following is a further detailed description of a method for identifying, judging, and controlling abnormal movement of cross rolls in a PC rolling mill, based on the accompanying drawings and specific embodiments of the present invention.

[0047] To facilitate understanding of this technical solution, its working principle and process are described below:

[0048] In terms of overall design, this technical solution combines the characteristics of cross-head oscillation current control. It employs cross-head oscillation current detection and locking control to address the steady-state current and startup current conditions of the cross-head oscillation, preventing accidents such as cross-head jamming caused by sudden anomalies. Simultaneously, it recognizes that when the cross roll jams, there will inevitably be a significant speed difference between the given speed and the feedback speed of the cross roll motor. Judging jamming based on this principle is intuitive and reasonable. Therefore, this technology combines the speed difference changes of the cross roll motor and the changes in the cross-head oscillation torque current during no-load, startup, and steady-state operation to identify whether the cross roll is malfunctioning, thereby achieving locking control. A double-insurance identification, judgment, and control method that can know the cross roll status in advance is established. For the specific control process, please refer to [link to relevant documentation]. Figure 1 .

[0049] like Figure 2 , 3 As shown, the oscillation of the cross rollers at the cross angle is transmitted to the cross baffle via the cross roller motor, clutch, brake, bevel gear, and worm gear. The work roller and support roller bearings are fixed to the cross baffle. The left and right movement of the cross baffle causes the upper and lower rollers to form a certain angle β. The upper cross baffle on the working side can move left and right, while the lower cross baffle is fixed. On the drive side, the upper cross baffle is fixed, while the lower cross baffle can move left and right.

[0050] The technical solution establishes a method for identifying, judging, and controlling abnormal movements of the cross rolls in a PC rolling mill. The corresponding control logic and process are as follows:

[0051] After the motor starts, by real-time monitoring and judgment of the motor speed and torque current, the identification and control of abnormal cross roller operation are completed. The identification and control specifically includes the following steps, see... Figure 1 :

[0052] S1: Real-time acquisition of motor feedback speed and comparison with given speed. When the difference between the given speed and the motor feedback speed is greater than or equal to the set threshold, the first alarm is triggered and the process proceeds to step S3; otherwise, monitoring continues.

[0053] S2: According to the set cycle, the torque current is collected in real time within the set time period, and the abnormal movement of the cross roller is identified based on the data processing results of each torque current within the collection time period. When the data processing result is greater than or equal to the set threshold, the second alarm is triggered and the process proceeds to step S3; otherwise, monitoring continues.

[0054] S3: Determine the alarm category. If it is only the first alarm, or if the first alarm and the second alarm occur simultaneously, count the number of first alarms and notify the corresponding PC mill cross roll control processing based on the number of first alarms. If it is only the second alarm, notify the planned processing arrangement.

[0055] The aforementioned "identification of abnormal cross-roller operation based on the data processing results of each torque current within the acquisition period" includes two methods: identifying abnormal cross-roller operation based on the mean value of each torque current within the acquisition period, and identifying abnormal cross-roller operation based on the variance value of each torque current within the acquisition period. Each of these two identification methods has its own threshold set according to the specific operating state. Through these processing settings, the technical solution can ultimately be put into practical use.

[0056] Since the monitoring and identification control processing is performed on a per-stand basis, when the number of alarms exceeds the set limit, an alarm is triggered and the PC angle adjustment function of the current mill is locked. Operators then adjust the PC angles of the remaining mills according to the actual situation. This configuration approach aims to reduce downtime costs.

[0057] To clearly understand this technical solution, the detection of the speed difference of the cross rollers, the detection of torque current, the determination based on the mean of torque current, and the determination based on the variance of torque current are explained separately below.

[0058] 1. Cross roller speed difference detection

[0059] The speed of the cross roller changes in accordance with the speed set by the PLC. Within a unit of time (1 second in this case), the difference between the speed set by the cross roller motor and the feedback speed acquired by the program exceeds a set threshold value Δ. us If the system detects that the cross roller is stuck, the operation of the cross roller motor will be interrupted and an alarm will be triggered.

[0060] Δ SPD =S REF -S FBK

[0061] Δ SPD Speed ​​difference between the given and feedback speeds of the cross roller motor

[0062] S REF Cross roller motor set speed

[0063] S FBK Cross roller motor feedback speed

[0064] When the speed difference Δ SPD Exceeding the set threshold value Δ us In other words, Δ SPD ≥Δ us If this happens, it is determined that there is a jamming problem with the cross rollers.

[0065] When a speed difference occurs in the cross rollers, it indicates a relative change in load during the cross roller's operation. This could be due to factors such as jamming or a malfunction in the connecting mechanism. Therefore, in addition to speed comparison checks, the torque current needs to be checked. Interrupting the cross roller's operation at this point is to prevent the equipment failure from escalating and to automatically issue an alarm signal.

[0066] 2 Torque Current Detection

[0067] Based on the control principle of cross-roller frequency converters, the vector control principle of AC frequency converters is used in the control of cross-roller frequency converters to decouple the torque current feedback (Iq). In vector control, the current I1 is decomposed into a magnetic flux current component (Id) and its orthogonal torque component (Iq), which are controlled separately. The magnetic flux is calculated based on the speed, and the magnetic flux current (Id) is proportional to the required magnetic flux for control. When the load torque increases, only the torque current proportional to the required torque increases. However, in the control of AC motors, since the excitation control and speed control of the motor are coupled together, unlike DC motors which can be controlled independently, decoupling is necessary first. The process involves converting from 3-phase to 2-phase stationary and then back to 2-phase rotating, maintaining a constant rotating magnetic field and motor power during the conversion process. This allows the calculation of the orthogonal torque component (Iq), which is the torque current.

[0068] 2.1 Acquiring Torque Current under Normal Conditions (Data Acquisition)

[0069] The torque and current count values ​​under normal conditions are collected using an ODG (Online Data Acquisition) system. Under the downward cross-roller operation mode, the normal torque and current are generally below 100%. The ODG calculation shows that 4000 count values ​​correspond to 100%. The machine current of the cross-roller when it is open and not in contact with the roll bearing housing is within 85% of the rated current of the cross-roller motor.

[0070] The formula for calculating torque current is as follows:

[0071]

[0072] After recording the actual current, the transmission software sends the actual current to the PLC according to the correspondence between 100% current and 4000 CNT value.

[0073] in:

[0074] C x Actual current calculation count value

[0075] C: The count value corresponding to 100% current (4000 in this case, which is the conventional correspondence between the PLC and the drive feedback current).

[0076] I q Torque current feedback

[0077] I e Rated current (i.e., 100% current, which is 98 amps in this case).

[0078] The above section on torque current detection and data acquisition under normal conditions (section 2.1) is presented as background information for general knowledge purposes. The purpose of this explanation is simply to introduce the source of torque current. In practice, real-time acquisition based on ODG is sufficient.

[0079] 2.2 Abnormal detection and judgment of torque current

[0080] 2.2.1 Judgment of average torque current of cross rollers

[0081] The percentage of the average periodic torque current collected by the program within a unit time (1 second in this case) is the feedback torque current. A torque-to-current ratio exceeding the set threshold α indicates an abnormality such as jamming of the cross rollers. This α ratio is based on the upper limit of the feedback value x during normal use. UF With compensation value Δ α The sum is definite. Δ αThe value is generally (-30% to 60%) depending on the load. There are generally three operating conditions for the cross roller motor: startup, steady state, and no-load. Taking a hot rolling production line F1 as an example, when the cross roller motor starts rotating forward, the cross angle increases, and the current relative to the startup current Δ... α Take 20%. However, during reversal, the cross angle decreases, resulting in a relatively larger starting current Δ. α Take 50%. Take 0% for steady-state and no-load conditions.

[0082] α=x UF +Δ α

[0083] α: Threshold torque current (unit: percentage of motor rated current)

[0084] Δ α Compensation value unit: percentage of motor rated current

[0085] x UF Upper limit torque current unit: percentage of motor rated current

[0086] The average torque current per unit time is calculated by recording the torque current detected by the program n times within a unit time and then calculating the average value. The specific formula is as follows:

[0087]

[0088] Average torque current unit: percentage of motor rated current

[0089] X1: Torque current collected in the first cycle (unit: percentage of motor rated current)

[0090] X2: Torque current collected in the nth cycle. Unit: percentage of motor rated current.

[0091] n: Number of program scan cycles, which depends on the program scan time and sampling unit.

[0092] when This indicates that there is an abnormality such as jamming in the cross rollers.

[0093] 2.2.2 Judgment of Torque Current Fluctuation Amplitude of Cross Rollers

[0094] In this case, we assume that the torque current data X1, X2, X3, X4, X5, X6, X7, X8, X9......X are sampled in each scan cycle of the program. n In this context, the formula for calculating the variance of the sample is as follows:

[0095]

[0096] sn 2 Torque-current variance

[0097] When S n When ≥σ,

[0098] σ: Permissible fluctuation range

[0099] The value of σ ranges from 0.05 to 0.5. Further, when under no-load conditions, the value is determined within the range [0.05, 0.1] based on the actual situation. The value is determined according to the installation accuracy of the motor and transmission mechanism; the lower the accuracy, the larger the value, and the larger the allowable fluctuation range. When under load, the value is determined within the range [0.1, 0.5] based on the actual situation. The value is determined according to the load condition; the larger the load, the larger the value, and the larger the allowable fluctuation range. This indicates a sudden and severe fluctuation in torque current, which is considered an abnormality such as jamming at the cross angle of the cross rollers.

[0100] 2.3 Torque and Current Judgment of Cross Roller Motor

[0101] When the speed of the cross roller is normal, determine the torque and current of the cross roller motor.

[0102] The torque current of the cross roller motor is divided into three stages based on the cross roller's movement: no-load, start-up, and steady-state. After the PLC receives the cross angle setting, the clutch releases and the brake closes, causing the cross roller motor to rotate under no-load. At this time, the no-load current of the cross roller motor is detected, and if the current feedback indicates it is normal, the brake is released and the clutch closes, at which point the start-up current is detected. After 5 seconds, the cross roller motor enters steady-state, and the steady-state current of the cross roller motor is detected. If, during this process, the average value of the feedback current over 1 second or the current fluctuation exceeds a threshold value, the clutch and brake are immediately released to lock and stop the cross angle change, and an overcurrent alarm is displayed on the screen.

[0103] Example:

[0104] On a hot rolling production line, F1 starts to reduce the crossing angle. The threshold count value for the torque current feedback of the unloaded crossing roller motor, i.e., x, is used to determine the starting threshold. UF =20% of the rated current is used as the threshold value for the no-load torque current of the cross rollers. Δ under no-load conditions α If the value is 0%, then:

[0105] α 空 =x UF +Δ α =20% + 0% = 20%

[0106] α 空 No-load threshold torque current (unit: percentage of motor rated current)

[0107] Δ αCompensation value unit: percentage of motor rated current

[0108] x UF Upper limit torque current unit: percentage of motor rated current

[0109] The average torque current per unit time is calculated by recording the torque current detected by the program n times within a unit time and then calculating the average value. The specific formula is as follows:

[0110]

[0111] Average torque current unit: percentage of motor rated current

[0112] X1: Torque current collected in the first cycle (unit: percentage of motor rated current)

[0113] X2: Torque current collected in the nth cycle. Unit: percentage of motor rated current.

[0114] n: Number of program scan cycles (in this case, 1s / 50ms = 20).

[0115] when This indicates that there is an abnormality such as jamming of the cross rollers and triggers an alarm.

[0116]

[0117] s n 2 Torque-current variance

[0118] When S n When ≥σ, (where Δ = 0.1 in this case)

[0119] That is: S n A value of ≥0.1 indicates that the torque current fluctuates drastically at an instant under no-load conditions. This indicates that there is an abnormality such as jamming of the cross roller under no-load conditions. When the PC motor operation torque current warning is detected, the PC operation interlock is immediately interrupted, the PC stops operating, and an alarm is triggered.

[0120] If the current and fluctuation amplitude are normal under no-load conditions, then the cross angle switching is initiated, and the starting current is detected. This case involves a production line x... UF Take the value 100%, Δ α Take 50% when starting in reverse.

[0121] Formula α 启 =x UF +Δ α =100% + 50% = 150%

[0122] α 启Threshold torque current unit: percentage of motor rated current

[0123] Δ α Compensation value unit: percentage of motor rated current

[0124] x UF Upper limit torque current unit: percentage of motor rated current

[0125] Δ α The value range is 50%.

[0126] The average torque current per unit time is calculated by recording the torque current detected by the program n times within a unit time and then calculating the average value. The specific formula is as follows:

[0127]

[0128] Average torque current unit: percentage of motor rated current

[0129] X1: Torque current collected in the first cycle (unit: percentage of motor rated current)

[0130] X2: Torque current collected in the nth cycle. Unit: percentage of motor rated current.

[0131] n: Number of program scan cycles (in this case, 1s / 50ms = 20).

[0132] when This indicates that there is an abnormality such as jamming of the cross roller, interrupts the control action, and provides a real-time alarm.

[0133]

[0134] s n 2 Torque-current variance

[0135] When S n When ≥σ, (where Δ is set to 0.3 in this case)

[0136] σ: Permissible fluctuation range

[0137] That is: S n A value of ≥0.3 indicates that the torque current fluctuates violently during the cross-roller action at startup. This indicates that there is an abnormality such as jamming of the cross roller during startup, and the startup control action is interrupted with a real-time alarm.

[0138] If the starting current is normal within 5 seconds, then perform steady-state current detection. (Similarly, in this case, a certain production line x...) UF Take the value 100%, Δ α Take 0% when starting in reverse

[0139] when This indicates an abnormality such as jamming of the cross rollers, interrupts control operations, and provides a real-time alarm. n A value of ≥0.3 indicates that the torque current fluctuates violently during the cross-roller action in steady state. This indicates that there is an abnormality such as jamming of the cross roller during startup, and the startup interruption control action is triggered with a real-time alarm.

Claims

1. A method for identifying and determining the abnormal action of the cross roll of a PC rolling mill, characterized in that: after the motor is started, the real-time monitoring and determination of the motor speed and the real-time monitoring and determination of the torque current are combined to complete the identification and determination of the abnormal action of the cross roll; specifically comprising the following steps: S1: Real-time acquisition of the motor feedback speed, and comparison with the given speed, when the difference between the given speed and the motor feedback speed is greater than or equal to the set threshold, the first alarm is triggered, and step S3 is entered, otherwise continue to monitor; S2: According to the set period, the real-time acquisition of the torque current is completed within the set time, and the identification and determination of the abnormal action of the cross roll is completed according to the data processing results of each torque current within the acquisition time, when the data processing result is greater than or equal to the set threshold, the second alarm is triggered, and step S3 is entered, otherwise continue to monitor; S3: Determine the category of the alarm, when it is only the first alarm, or when the first alarm and the second alarm occur at the same time, the number of first alarms is counted, and the corresponding control of the PC rolling mill cross roll is notified according to the number of first alarms; when it is only the second alarm, the scheduled processing arrangement is notified; The "identification and determination of the abnormal action of the cross roll according to the data processing results of each torque current within the acquisition time" in step S2 comprises: the identification and determination of the abnormal action of the cross roll based on the mean value calculation results of each torque current within the acquisition time, and the identification and determination of the abnormal action of the cross roll based on the variance calculation results of each torque current within the acquisition time; When the identification and determination of the abnormal action of the cross roll is completed based on the mean value calculation results of each torque current within the acquisition time, the set threshold for comparison with the mean value calculation results is determined according to the following formula: In the formula, a = 0.2, b = 0.1, c = 0.05, d = 0.1, and e = 0.

5.

2. The method for identifying and determining the abnormal action of the cross roll of a PC rolling mill according to claim 1, characterized in that: ， The corresponding compensation value is set separately according to the four states of motor forward rotation start, motor reverse rotation start, no load, and load; : set threshold for comparison with the mean value calculation result, unit: motor rated current percentage; : upper torque current, unit: % of motor rated current; : compensation value, unit: motor rated current percentage. When in the motor forward rotation start state, the compensation value is determined as 20%; When in the motor reverse rotation start state, the compensation value is determined as 50%; When in the no load or load state, the compensation value is determined as 0%.

3. The method for identifying and determining the abnormal action of the cross roll of a PC rolling mill according to claim 2, characterized in that: The state of the motor in no load or load is determined according to the action of the clutch.

4. The method for identifying and determining the abnormal action of the cross roll of a PC rolling mill according to claim 1, characterized in that: When the identification and determination of the abnormal action of the cross roll is completed based on the variance calculation results of each torque current within the acquisition time, the set threshold for comparison with the variance calculation results is set separately according to the two states of no load and load; When in the no load state, the set threshold is determined within the interval [0.05, 0.1] according to the actual situation; When in the load state, the set threshold is determined within the interval [0.1, 0.5] according to the actual situation. ​ ​ 5. The method for identifying, judging and controlling the cross roll action abnormality of a PC rolling mill according to claim 1, characterized in that: The judgment, identification and control of the cross roll action abnormality are performed for each stand, and the "control processing of the corresponding PC rolling mill cross roll according to the number of first alarms" in step S3 is specifically: Lock the current rolling mill PC angle adjustment function when the number of first alarms exceeds the set number.

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