Method for identifying, judging and controlling abnormal actions of cross rollers of PC (Personal Computer) rolling mill

Abstract

According to the recognition, judgment and control method based on the abnormal action of the cross rollers of the PC rolling mill, after the motor is started, the judgment, recognition and control of the abnormal action of the cross rollers are completed through real-time monitoring and judgment of the rotating speed of the motor and real-time monitoring and judgment of the torque current in cooperation with the real-time monitoring and judgment of the rotating speed of the motor. According to the recognition, judgment and control method based on the abnormal actions of the crossed rollers of the PC rolling mill, clamping stagnation of the crossed rollers can be determined in advance, planned arrangement space can be provided for specific treatment of the clamped crossed rollers in the later period, and therefore the shutdown cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of automatic control of metallurgical steel rolling, and in particular relates to an identification, judgment and control method based on abnormal movement of cross rolls of a PC rolling mill. Background Art

[0002] In existing operations, the limit signal judgment method is used to determine whether the cross roller is stuck. This is a post-judgment method, that is, the out-of-position signal will be generated only after the actual jam occurs. At this time, corresponding post-event processing is required according to the accident, including shutdown and replacement, on-site temporary matching, etc., which results in a huge waste of processing costs.

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

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

[0005] The invention application with application number: CN202110864490.X discloses "a method for characterizing the degree of cross-over of a hot rolling mill roll system". The zero adjustment process is used to monitor the opening gap of the mill arch, and dynamic pressure is performed in batches. The bearing return oil temperature formula is obtained by linear fitting method, and the return oil temperature of the mill support bearing under working condition is calculated, and then the lateral expansion of the bearing is obtained, and then the gap value is compared. When it is found that the dynamic gap of the mill support roller does not meet the standard requirements, shutdown measures are taken to readjust the gap.

[0006] The invention application with application number: CN202111536399.1 discloses "a method for pre-determining overload of a hot rolling mill roll motor". The method includes: pre-setting a current sampling time; periodically sampling the roll motor current data 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; judging whether the maximum overload rate is less than the overload rate judgment threshold; judging 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, it is judged that the hot rolling mill roll motor will be overloaded. Summary of the invention

[0007] The object of the present invention is to provide a solution that can pre-complete the identification and determination of cross roller jamming so that maintenance can be planned and arranged, thereby reducing downtime costs.

[0008] In order to achieve the above technical objectives, the present invention provides a method for identifying, judging and controlling abnormal cross roll movement of a PC rolling mill, and the technical solution thereof is as follows:

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

[0010] After the motor is started, the abnormal movement of the cross roller is identified and controlled through real-time monitoring and judgment of the motor speed and real-time monitoring and judgment of the torque current.

[0011] Further,

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

[0013] S1: collect the motor feedback speed in real time and compare it 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 the process goes to step S3, otherwise the monitoring continues;

[0014] S2: According to the set cycle, the real-time acquisition of the torque current is completed within the set time, and the abnormality of the cross roller movement is determined and identified 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 the process goes to step S3, otherwise the monitoring continues;

[0015] S3: Determine the type of alarm. When it is only the first alarm, or when the first alarm and the second alarm occur at the same time, count the number of first alarms and notify the corresponding PC mill cross roll control processing according to the number of first alarms; when it is only the second alarm, notify the planning and processing arrangements.

[0016] Further,

[0017] The step S2 of "completion of determination and identification of abnormal cross roller movement according to the data processing results of each torque current within the acquisition time" includes:

[0018] Based on the average calculation results of each torque current within the acquisition time, the abnormal cross roller movement is judged and identified.

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

[0020] Further,

[0021] When the determination and identification of the abnormal movement of the cross roller is completed based on the average calculation result of each torque current within the acquisition time, the set threshold 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: The set threshold used to compare with the mean calculation result, unit: percentage of motor rated current;

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

[0026] Δ α : Compensation value, percentage of rated current of a single machine.

[0027] Further,

[0028] The corresponding compensation value is set according to the four states of motor forward start, motor reverse start, no-load and load;

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

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

[0031] When it is no-load or loaded, it is determined according to the compensation value of 0%.

[0032] Further,

[0033] The action of the clutch determines whether the motor is in an unloaded or loaded state.

[0034] Further,

[0035] When the determination and identification of the abnormal movement of the cross roller is completed based on the variance calculation results of each torque current within the acquisition time, the set 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 load is not loaded, the threshold is set according to the actual situation and the value is determined within the interval [0.05, 0.1];

[0037] When under load, the threshold is set according to the actual situation and the value is determined within the interval [0.1, 0.5].

[0038] Further,

[0039] The determination, identification and control of abnormal cross roll movement are carried out for each stand, and accordingly, the step S3 of "controlling the cross roll of the corresponding PC mill according to the number of first alarms" is specifically as follows:

[0040] When the number of the first alarm exceeds the set number, the current mill PC angle adjustment function is locked, and the operator adjusts the remaining mill PC angles according to the actual situation.

[0041] The present invention is a method for identifying, judging and controlling abnormal cross-roller movement of 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 completes the identification, judgment and control of abnormal cross-roller movement. The real-time monitoring and judgment of torque current can realize the early prediction and identification of whether the cross-roller is stuck, so that the processing of the cross-roller when it is stuck can be planned in advance, thereby reducing the downtime cost; the real-time monitoring and judgment of motor speed exists as a double insurance setting for abnormal identification and judgment; the bottom limit monitoring exists to compensate for and form monitoring omissions caused by gaps in the torque current cycle, and is a setting of insurance nature. When performing specific abnormal identification and judgment based on torque current, specific identification and judgment are established from the horizontal and vertical dimensions respectively, so that different types of jams in various situations can be taken into account and comprehensively monitored and identified. 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 article. These two types of judgments can be used to identify different types of jams. The so-called horizontal identification and judgment refers to the setting of corresponding thresholds based on each working state mentioned in the article, so that the judgment is in line with the actual situation.

[0042] The invention discloses a method for identifying, judging and controlling abnormal cross roll movement of a PC rolling mill, which can realize early determination of cross roll jam and provide planned arrangement space for later specific treatment of the jammed cross roll, thereby reducing downtime costs. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0045] Figure 3 Based on Figure 2 Schematic diagram of the working process of the cross rolling mill. DETAILED DESCRIPTION

[0046] Below, a method for identifying, determining and controlling abnormal cross roll motion of a PC rolling mill according to the present invention is further described in detail based on the accompanying drawings and specific implementation methods of the specification.

[0047] To facilitate the understanding of this technical solution, the working principle and process are introduced as follows:

[0048] In terms of overall design concept, this technical solution combines the characteristics of cross-head swing current control, and adopts cross-roller mill cross-swing current detection and locking control for the current conditions involving the cross-head swing steady-state current and the current during the startup process, so as to prevent abnormal accidents such as cross-head jamming caused by sudden abnormalities. At the same time, it is noted that when the cross-roller is stuck, there must be an obvious speed difference between the given speed and the feedback speed of the cross-roller motor. The judgment of jamming based on this principle is also intuitive and reasonable. Therefore, this technology combines the speed difference change and no-load of the cross-roller motor, the change of the cross-angle swing torque current during startup and steady state to identify whether the cross-roller action is abnormal, and then realize locking control. Establish a double-insurance identification, judgment and control method that can know the cross-roller status in advance. For the specific control process, see Figure 1 .

[0049] like Figure 2 , 3 As shown, the cross roller cross angle swing is rotated by the cross roller motor, and is transmitted to the cross baffle through the clutch, brake, bevel gear, worm gear, and the working roll and support roll bearings are fixed on the cross baffle. The left and right movement of the cross baffle makes the upper and lower rolls form a certain angle β. The upper cross baffle on the working side can move left and right, and the lower cross baffle is fixed. The upper cross baffle on the transmission side is fixed, and the lower cross baffle can move left and right.

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

[0051] After the motor is started, the real-time monitoring and determination of the motor speed is combined with the real-time monitoring and determination of the torque current to complete the determination, identification and control of the abnormal movement of the cross roller. The determination, identification and control specifically include the following steps: Figure 1 :

[0052] S1: collect the motor feedback speed in real time and compare it 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 the process goes to step S3, otherwise the monitoring continues;

[0053] S2: According to the set cycle, the real-time acquisition of the torque current is completed within the set time, and the abnormality of the cross roller movement is determined and identified 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 the process goes to step S3, otherwise the monitoring continues;

[0054] S3: Determine the type of alarm. When it is only the first alarm, or when the first alarm and the second alarm occur at the same time, count the number of first alarms and notify the corresponding PC mill cross roll control processing according to the number of first alarms; when it is only the second alarm, notify the planning and processing arrangements.

[0055] The above-mentioned "completion of determination and identification of abnormal cross-roller movement based on the data processing results of each torque current within the acquisition time" includes: completion of determination and identification of abnormal cross-roller movement based on the mean calculation results of each torque current within the acquisition time, and completion of determination and identification of abnormal cross-roller movement based on the variance calculation results of each torque current within the acquisition time. The two determinations and identifications are respectively determined by setting thresholds according to specific working states. After the above processing and setting, the technical solution can finally be put into practical use.

[0056] Since the control processing of monitoring and identification judgment is carried out for each stand, when the number of the first alarm exceeds the set number, the alarm is triggered and the PC angle adjustment function of the current rolling mill is locked, and the operator adjusts the PC angles of the remaining rolling mills according to the actual situation. This setting and processing is generally close to the original intention of reducing downtime costs.

[0057] In order to clearly understand the present technical solution, the detection of the cross-roller speed difference, the detection of the torque current, the determination based on the torque current mean value and the determination based on the torque current variance involved therein are respectively explained below.

[0058] 1. Cross roller speed difference detection

[0059] The cross roller speed changes with the change of the PLC given speed. Within a unit time (1 second in this case), the difference between the cross roller motor given speed collected by the program and the cross roller motor feedback speed exceeds the set threshold value Δ us When the cross roller is stuck, it is judged that the cross roller is stuck, and the action of the cross roller motor is interrupted and an alarm is sounded.

[0060] Δ SPD =S REF -S FBK

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

[0062] S REF : Cross roller motor given speed

[0063] S FBK : Cross roller motor feedback speed

[0064] When the speed difference Δ SPD Exceeding the set threshold value Δ us , that is to say, Δ SPD ≥Δ us When the cross roller is stuck, it is judged that there is a jam.

[0065] When the cross roller has a speed difference, it means that the load has changed relatively during the cross head movement. There are factors such as stagnation or abnormal connection mechanism. Therefore, it is necessary to check the torque current on the basis of speed comparison. At this time, the purpose of interrupting the cross roller movement is to avoid the expansion of equipment failure and automatically send out an alarm signal.

[0066] 2Torque current detection

[0067] Combined with the control principle of the cross-roller inverter, the vector control principle of AC frequency conversion is used in the cross-roller inverter control to decouple the torque current feedback (Iq). In vector control, the current I1 is decomposed into the flux current (Id) component and its orthogonal torque component (Iq), and they are controlled separately. The flux formula is calculated based on the speed, and the flux current (Id) is proportional to the required flux for control. When the load torque increases, only the torque current proportional to the required torque increases. In the control of AC motors, since the excitation control and the transfer control of the motor are coupled together, unlike DC motors, they can be controlled independently, so they must be decoupled first. From 3 phases to 2 phases of static, and then to 2 phases of rotation, during the conversion process, the rotating magnetic field is kept unchanged and the motor power is kept unchanged. Thus, the orthogonal torque component (Iq), that is, the torque current, is calculated.

[0068] 2.1 Collecting torque current under normal conditions (data collection)

[0069] Use ODG (online data acquisition system) to collect the torque current count value in normal state. When the cross roller is in the downward cross action mode, the normal torque current is generally within 100%, and the ODG calculation correspondence is 4000 count values ​​corresponding to 100%. The turning current of the cross roller in the case of opening the non-contact roller bearing seat is within 85% of the rated current of the cross roller motor.

[0070] The calculation formula of torque current is as follows

[0071]

[0072] After the transmission software records the actual current, it sends the actual current to the PLC based on the correspondence between 100% current and 4000CNT value.

[0073] in:

[0074] C x : Actual current calculation count value

[0075] C: Count value corresponding to 100% current (4000 is used in this case, which is the agreed correspondence between PLC and transmission feedback current)

[0076] I q : Torque current feedback

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

[0078] The above 2 torque current detection and 2.1 acquisition of torque current under normal conditions (data acquisition) are for popular science background knowledge. The purpose of the explanation is only to introduce the source of torque current. In practice, it is only necessary to perform real-time acquisition based on ODG.

[0079] 2.2 Abnormal detection and judgment of torque current

[0080] 2.2.1 Determination of average torque current of cross roller

[0081] When the average periodic torque current percentage x collected by the program in the unit time (1 second in this case) exceeds the set threshold torque current ratio α, it indicates that the cross roller is blocked or other abnormal conditions. The α ratio is based on the upper limit of the feedback value x during normal use. UF and compensation value Δ α The sum of Δ α The value is generally (-30%-60%) according to the load condition. There are generally three conditions for the operation of 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 is started in the forward direction, the cross angle becomes larger relative to the current at startup.α Take 20%. When the reverse direction is reversed, the cross angle becomes smaller and the starting current is relatively large. α Take 50%. Take 0% in steady state and no-load state.

[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 method used to calculate the average torque current per unit time is to record the n torque currents detected by the program scan per unit time and then calculate 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: The number of program scan cycles, which depends on the program scan time and sampling unit.

[0092] when This indicates that the cross roller is stuck or has other abnormal conditions.

[0093] 2.2.2 Determination of the fluctuation amplitude of the cross-roller torque current

[0094] In this case, we assume that the torque current data of x sampled in each scanning cycle of the program

[0095] X1, X2, X3, X4, X5, X6, X7, X8, X9......X n , the sampling variance calculation formula is as follows:

[0096]

[0097] s n 2 : Torque current variance value

[0098] When S n When ≥σ,

[0099] σ: Permissible fluctuation range

[0100] Among them, the value range of σ is (0.05-0.5). Furthermore, when it is unloaded, combined with the actual situation, the value is determined within the interval [0.05, 0.1]; it is determined according to the installation accuracy of the motor and transmission mechanism. The worse the accuracy, the larger the value, and the larger the value, the larger the allowable fluctuation range. When it is loaded, combined with the actual situation, the value is determined within the interval [0.1, 0.5]; the value is determined according to the load situation. The larger the load, the larger the value, and the larger the value, the larger the allowable fluctuation range; it indicates that the torque current fluctuates violently in an instant, and it is determined that the cross roller has abnormal conditions such as cross angle blocking.

[0101] 2.3 Cross roller motor torque current determination

[0102] When the cross roller speed is normal, determine the cross roller motor torque and current conditions.

[0103] The torque current of the cross roller motor is divided into three stages according to the cross roller action: no-load, start-up, and steady state. After the PLC receives the cross angle setting, the clutch is released and the brake is closed, and the cross roller motor rotates without load. At this time, the no-load current of the cross roller motor is detected, and the current feedback is judged to be normal. The brake is released and the clutch is closed, and the starting current is detected at this time. After 5 seconds, the cross roller motor enters the steady state, and the steady-state current of the cross roller motor is detected. If the 1-second average value of the feedback current or the current fluctuation amplitude exceeds the threshold value during this process, the clutch and brake are directly released to lock the cross angle change and an overcurrent alarm is prompted on the screen.

[0104] Example:

[0105] When the hot rolling production line F1 starts to reduce the cross angle, the cross roller motor starts the threshold judgment count value of the no-load cross roller motor torque current feedback, that is, x UF = 20% of the rated current is used as the cross roller no-load torque current threshold value for judgment. α If the value is 0%, then:

[0106] α 空 =x UF +Δ α =20%+0%=20%

[0107] α 空 : No-load threshold torque current unit: percentage of motor rated current

[0108] Δ α : Compensation value unit: percentage of motor rated current

[0109] x UF: Upper limit torque current unit: percentage of motor rated current

[0110] The method used to calculate the average torque current per unit time is to record the n torque currents detected by the program scan per unit time and then calculate the average value. The specific formula is as follows:

[0111]

[0112] Average torque current unit: percentage of motor rated current

[0113] X1: Torque current collected in the first cycle Unit: Percentage of motor rated current

[0114] X2: Torque current collected in the nth cycle Unit: percentage of motor rated current

[0115] n: Number of program scan cycles (in this case, 1s / 50ms=20).

[0116] when When the cross roller is blocked, it indicates an abnormal situation and an alarm is sounded.

[0117]

[0118] s n 2 : Torque current variance value

[0119] When S n ≥σ, (where σ=is set to 0.1 in this case)

[0120] That is: S n ≥0.1 indicates that the torque current has a sharp instantaneous angle fluctuation under no-load conditions. At this time, it is determined that there is an abnormal situation such as jamming of the cross roller under no-load conditions. When the PC motor action torque current warning is detected, the PC action chain is immediately interrupted, the PC stops moving, and an alarm is sounded.

[0121] If the current and fluctuation amplitude are normal when no-load, the cross angle conversion is started and the starting current detection is performed. UF Take the value 100%, Δ α 50% when starting in reverse

[0122] Formula α 启 =x UF +Δ α =100%+50%=150%

[0123] α 启 :Threshold torque current unit: percentage of motor rated current

[0124] Δα : Compensation value unit: percentage of motor rated current

[0125] x UF : Upper limit torque current unit: percentage of motor rated current

[0126] Δ α : The value range is 50%

[0127] The method used to calculate the average torque current per unit time is to record the n torque currents detected by the program scan per unit time and then calculate the average value. The specific formula is as follows:

[0128]

[0129] Average torque current unit: percentage of motor rated current

[0130] X1: Torque current collected in the first cycle Unit: Percentage of motor rated current

[0131] X2: Torque current collected in the nth cycle Unit: percentage of motor rated current

[0132] n: Number of program scan cycles (in this case, 1s / 50ms=20).

[0133] when It indicates that there is an abnormal situation such as jamming of the cross roller, and the control action is interrupted and an alarm is prompted in real time.

[0134]

[0135] s n 2 : Torque current variance value

[0136] When S n ≥σ, (where σ=is set to 0.3 in this case)

[0137] σ: Permissible fluctuation range

[0138] That is: S n ≥0.3 indicates that the torque current has a momentary violent fluctuation in the cross action at startup. At this time, it is determined that there is an abnormal situation such as jamming of the cross roller during startup, and the startup interrupts the control action and prompts an alarm in real time.

[0139] If the starting current is normal within 5S, then the steady-state current detection is performed. UF Take the value 100%, Δ α 0% when reverse start

[0140] when When the cross roller is blocked, it indicates that there is an abnormal situation such as blocking, and the control action is interrupted and an alarm is prompted in real time. n ≥0.3 indicates that the torque current has momentary violent fluctuations in the cross action when in steady state. At this time, it is judged that there is an abnormal situation such as jamming of the cross roller during startup, and the startup interruption control action is started and an alarm is prompted in real time.

Claims

1. A method for identifying, judging and controlling abnormal cross roll movement of a PC rolling mill, characterized in that: After the motor is started, the abnormal movement of the cross roller is identified and controlled through real-time monitoring and judgment of the motor speed and real-time monitoring and judgment of the torque current.

2. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 1, characterized in that: The determination, identification and control specifically include the following steps: S1: collect the motor feedback speed in real time and compare it 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 the process goes to step S3, otherwise the monitoring continues; S2: According to the set cycle, the real-time acquisition of the torque current is completed within the set time, and the abnormality of the cross roller movement is determined and identified 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 the process goes to step S3, otherwise the monitoring continues; S3: Determine the type of alarm. When it is only the first alarm, or when the first alarm and the second alarm occur at the same time, count the number of first alarms and notify the corresponding PC mill cross roll control processing according to the number of first alarms; when it is only the second alarm, notify the planning and processing arrangements.

3. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 2, characterized in that: The "completion of determination and identification of abnormal cross roller movement according to the data processing results of each torque current within the acquisition time" in step S2 includes: Based on the average calculation results of each torque current within the acquisition time, the abnormal cross roller movement is judged and identified. And based on the variance calculation results of each torque current within the acquisition time, the abnormal movement of the cross roller is determined and identified.

4. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 3, characterized in that: When the determination and identification of the abnormal movement of the cross roller is completed based on the average calculation result of each torque current within the acquisition time, the set threshold for comparison with the average calculation result is determined according to the following formula: α=x UF +D α , In the above formula, α: The set threshold used to compare with the mean calculation result, unit: percentage of motor rated current; x UF : Upper limit torque current, unit: percentage of motor rated current; Δ α : Compensation value, percentage of rated current of a single machine.

5. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 4, characterized in that: The corresponding compensation value is set according to the four states of motor forward start, motor reverse start, no-load and load; When the motor is in forward rotation start state, it is determined according to the 20% compensation value; When the motor is in reverse start state, it is determined according to the 50% compensation value; When it is no-load or loaded, it is determined according to the compensation value of 0%.

6. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 5, characterized in that: The action of the clutch determines whether the motor is in an unloaded or loaded state.

7. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 3, characterized in that: When the determination and identification of the abnormal movement of the cross roller is completed based on the variance calculation results of each torque current within the acquisition time, the set threshold used for comparison with the variance calculation results is set separately according to the two states of no-load and load; When the load is not loaded, the threshold is set according to the actual situation and the value is determined within the interval [0.05, 0.1]; When under load, the threshold is set according to the actual situation and the value is determined within the interval [0.1, 0.5].

8. The method for identifying, judging and controlling abnormal cross roll motion of a PC rolling mill according to claim 1, characterized in that: The determination, identification and control of abnormal cross roll movement are carried out for each stand, and accordingly, the "control processing of the corresponding PC mill cross roll according to the number of first alarms" in step S3 is specifically as follows: When the number of the first alarm exceeds the set number, the current rolling mill PC angle adjustment function is locked.

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