A method for predicting breakage and winding of a twenty-roller rolling mill

Abstract

The present application relates to a kind of twenty roller mill strip break and roll winding prediction control method, comprising the following steps: S1 is judged as normal rolling process, S2 host current and the rate of change of speed prediction control, S3 prediction control analysis and result, pass through control fast opening speed regulating valve opening degree to improve the emergency opening speed of roll system, emergency stop time is related to strip break and roll winding, it is necessary to take on-line detection to reduce strip break and roll winding, for the detection mode of strip break and roll winding, by increasing the current of rolling mill main drive motor and the rate of change of speed, as necessary means to reduce the winding rate, improve the accuracy and response time of strip break and roll winding prediction, can effectively avoid strip break and roll winding, and can make early warning, method is convenient, give full play to the production capacity of twenty roller mill.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cold-rolled silicon steel rolling technology, in particular to a twenty-high rolling mill strip break and roll winding prediction control method. BACKGROUND

[0002] The twenty-high rolling mill is a rolling mill specially used for producing special steel, which absorbs the advantages of multi-roller rolling mill and four-roller rolling mill, has small work roll diameter, and has functions of roll shifting, eccentricity adjustment, and plate shape adjustment, and has more advantages in plate shape control and thickness control. Due to defects of silicon steel hot-rolled materials and plate shape problems in the rolling process, the strip break phenomenon often occurs in the cold rolling process under the strip tension, which is called strip break, and often causes damage to the surface finish of each roll in the rolling mill roll system, which is called roll winding, causes interruption of rolling, roll surface scratches, and even damage to the support roll and the intermediate roll, causes abnormal peeling of the roll surface, and also causes damage to the equipment in the rack. It also needs a long time to handle. The strip break and roll winding failure not only affects the normal continuous production of the mill group, but also greatly increases the rolling cost. It can be said that the strip break and roll winding are one of the problems restricting the continuous production of the twenty-high rolling mill. SUMMARY

[0003] The present application provides a twenty-high rolling mill strip break and roll winding prediction control method, which improves the emergency opening speed of the roll system, improves the accuracy and response time of the strip break and roll winding prediction, and can effectively avoid the strip break and roll winding.

[0004] In order to achieve the above purpose, the following technical scheme is adopted in the present application:

[0005] A twenty-high rolling mill strip break and roll winding prediction control method, comprising the following steps:

[0006] S1, judging as a normal rolling process;

[0007] S2, main machine current and speed change rate prediction control:

[0008] When it is not the 5th pass, 7-10% of the rated current change amount and 1-2% of the rated speed change amount of the rolling mill main drive motor appear within 40ms to judge as strip break, that is, ΔI act ∈(0.07-0.1)I e And ΔV act ∈(0.01-0.02)V e ; 40ms within the rolling mill main drive motor current appears ≥11% rated current change amount, and 40ms within the rolling mill main drive motor speed appears ≥3% rated speed change amount to judge as roll winding, that is, ΔI act ≥0.11I e And ΔV act ≥0.03V e ;

[0009] In the 5th pass, the change of the main drive motor current of the rolling mill of 5-7% of the rated current and the change of the main drive motor speed of 0.3-0.5% of the rated speed within 40ms are judged as the broken strip, namely ΔI act ∈(0.05-0.07)I e and ΔV act ∈(0.003-0.005)V e ; the change of the main drive motor current of the rolling mill of ≥8% of the rated current and the change of the main drive motor speed of ≥1% of the rated speed within 40ms are judged as the roll winding, namely ΔI act ≥0.08I e and ΔV act ≥0.01V e ;

[0010] wherein, I e is the rated current of the main drive motor of the rolling mill, ΔI act is the actual current change of the main drive motor of the rolling mill, V e is the rated speed of the main drive motor of the rolling mill, and ΔV act is the actual speed change of the main drive motor of the rolling mill;

[0011] S3, pre-estimation control analysis and result:

[0012] (1) before the broken strip, when the change of the main drive motor current of the rolling mill is above 11%, the roll winding phenomenon will occur; if the change of the main drive motor current of the rolling mill is below 5%, it is determined that the roll winding will not occur;

[0013] (2) in order to control the piston moving speed of the rolling mill pressure cylinder, the fast opening speed regulating valve is controlled to make the piston moving speed 100±5mm / s, and the fast opening response time of the hydraulic system is controlled to be 0.28-0.35s;

[0014] (3) through the change of the main motor current and speed, the broken strip and roll winding are warned 0.2-0.6s in advance.

[0015] Further, the judgment of the normal rolling process includes that the tension has been established, there is a strip in the rack, the tension control mode is the roll gap adjustment control, and the rolling mill speed is greater than the limit speed.

[0016] Further, the tension has been established is confirmed by the actual value of the tension being greater than the minimum tension value, and the minimum tension value is 10±2% of the set tension.

[0017] Further, the limit speed is 60±3m / min.

[0018] Compared with the prior art, the beneficial effects of the present application are:

[0019] 1) By controlling the fast opening speed of the speed regulating valve to improve the roll emergency opening speed, the emergency stop time is related to the broken strip winding roll, and it is necessary to take online detection to reduce the broken strip winding roll;

[0020] 2) For the detection method of the broken strip winding roll, by increasing the rolling mill main drive motor current and the speed change rate, as a necessary means to reduce the winding roll rate, the accuracy and response time of the broken strip winding roll estimation can be improved, which can effectively avoid the broken strip winding roll;

[0021] 3) Early warning can be made, the method is convenient, and the production capacity of the 20-roll rolling mill can be fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a method flowchart of the present application. DETAILED DESCRIPTION

[0023] The specific embodiments of the present application will be further described below in conjunction with the accompanying drawings:

[0024] See Figure 1 , is a method flowchart of the present application. The present application is a broken strip and winding roll estimation control method for a 20-roll rolling mill, comprising the following steps:

[0025] S1, judging as a normal rolling process;

[0026] S1.1, confirming that the tension has been established by the actual value of the tension being greater than the minimum tension value, i.e. T act >0.1T ref ;

[0027] Among them, the minimum tension value is 10% of the set tension, T act is the actual value of the tension, and T ref is the set tension;

[0028] S1.2, there is a strip in the stand;

[0029] The rolling mill tracking function module confirms that there is a strip in the stand;

[0030] S1.3, confirming the tension control mode;

[0031] The tension control mode has two kinds, the unwinder torque control and the roll gap adjustment control, and the tension control mode is the roll gap adjustment control as the condition for judging the normal rolling;

[0032] S1.4, the rolling speed is greater than the limit speed;

[0033] The rolling speed greater than the limit speed confirms that the broken strip judgment condition is met, i.e. V act >V lim , the limit speed is set to 60 m / min, wherein V actV is the rolling mill speed lim V is the limit speed.

[0034] S2, host current and speed change rate estimation control

[0035] The traditional broken strip detection means has tension, speed and thickness detection to judge, and the three ways are passive detection, and need to avoid the error of detection signal to cause false alarm, need certain threshold setting and delay setting, so the time from the appearance of broken strip to the system giving broken strip alarm is about 0.8 seconds, the estimation control is realized by the soft measurement way of host current and speed change, and the content of host current and speed change rate estimation control in the method is as follows:

[0036] Non-5th pass: (1) 40ms within the appearance of 7% rated current change and 1% rated speed change of rolling mill main drive motor to judge as broken strip, that is ΔI act =0.07I e And ΔV act =0.01V e ;

[0037] (2) 40ms within the appearance of 11% rated current change of rolling mill main drive motor, and 40ms within the appearance of 3% rated speed change of rolling mill main drive motor to judge as winding roll, that is ΔI act =0.11I e And ΔV act =0.03V e ;

[0038] 5th pass: (1) 40ms within the appearance of 5% rated current change and 0.3% rated speed change of rolling mill main drive motor to judge as broken strip, that is ΔI act =0.05I e And ΔV act =0.003V e ;

[0039] (2) 40ms within the appearance of 8% rated current change of rolling mill main drive motor, and 40ms within the appearance of 1% rated speed change of rolling mill main drive motor to judge as winding roll, that is ΔI act =0.08I e And ΔV act =0.01V e .

[0040] Wherein, I e is the rated current of rolling mill main drive motor, ΔI act is the actual current change of rolling mill main drive motor, V e is the rated speed of rolling mill main drive motor, and ΔV actThe actual speed variation of the main drive motor of the rolling mill.

[0041] S3, estimation control analysis and results:

[0042] (1) Before the strip breaks, the current of the main drive motor of the rolling mill increases, but the increase is different. When the increase of the current of the main drive motor of the rolling mill is greater than 11%, the phenomenon of roll winding will occur. If the increase of the current of the main drive motor is not large, i.e. less than 5%, it is determined that the roll winding will not occur.

[0043] (2) The moving speed of the piston of the rolling mill pressure cylinder is adjusted by the opening degree of the quick opening speed adjusting valve, the emergency opening speed of the roll system is increased, the opening degree of the quick opening speed adjusting valve is increased, the moving speed of the piston is increased from the original 60 mm / s to 100 mm / s, and the quick opening response time of the hydraulic system is increased to 0.3 s.

[0044] (3) Through the over-limit judgment of the current and speed variation of the main drive motor of the rolling mill, the strip breakage and roll winding can be alarmed 0.4 s in advance.

[0045] When the rolling mill unwinds and the thickness gauge detects 0.6 s before the strip breaks, the pre-judgment signal is triggered, the tension acting on the silicon steel strip suddenly decreases to 3.11 T, the 11.6% rated current variation and 3% rated speed variation in 40 ms, and it is judged that the strip breaks and the roll winding occurs. If the roll gap of the rolling mill cannot be opened in time when the strip breaks, it will become tensionless rolling, the rolling force will suddenly increase, at the same time, the friction force will also increase, and the work done by the friction force will be converted into heat energy, which will cause the temperature of the fracture of the steel strip to increase sharply, so that the local part of the silicon steel strip becomes molten state and adheres to the work roll, and then adheres to other rolls through the work roll to cause roll winding. Finally, only the strip breaks without roll winding to the second intermediate roll, which proves the effectiveness of the method.

[0046] The above examples are implemented on the premise of the technical scheme of the present application, and give detailed implementation modes and specific operation processes, but the protection scope of the present application is not limited to the above examples. The methods used in the above examples are conventional methods unless otherwise specified.

Claims

1. A method for predicting a break and a winding of a twenty-roller mill, characterized by, It comprises the following steps: S1, judging as normal rolling process; S2, host current and speed rate of change prediction control: When the rolling mill is not in the 5th pass, the strip breakage is determined if the current variation of the main drive motor of the rolling mill is greater than 7% of the rated current and the speed variation is greater than 1% of the rated speed within 40 ms, i.e. ΔI act ∈ (0.07-0.1) I e and ΔV act ∈ (0.01-0.02) V e ; 40 a roll jam is determined if a change in the current of the main drive motor of the rolling mill of > 11% of the rated current occurs within 40 ms and a change in the speed of the main drive motor of > 3% of the rated speed occurs within 40 ms, i.e. ΔI act ≥ 0.11 I e and ΔV act ≥ 0.03 V e ; In the 5th pass, the occurrence of a change in the current of the main drive motor of the rolling mill of 5-7% of the rated current and a change in the speed of 0.3-0.5% of the rated speed within 40 ms is judged to be a broken strip, namely ΔI act ∈ (0.05-0.07) I e and ΔV act ∈ (0.003-0.005) V e ; 40 a roll jam is determined if a change in current of the main drive motor of the rolling mill of ≥ 8% of the rated current occurs within 40 ms and a change in speed of the main drive motor of the rolling mill of ≥ 1% of the rated speed occurs within 40 ms, i.e. ΔI act ≥ 0.08 I e and ΔV act ≥ 0.01 V e ; wherein I e is the rolling mill main drive motor rated current, ΔI act is the rolling mill main drive motor actual current variation, V e is the rolling mill main drive motor rated speed, ΔV act is the rolling mill main drive motor actual speed variation; S3, prediction control analysis and results: (1) before the strip break, the rolling mill main drive motor current change amount is more than 11%, the winding roll phenomenon must occur; if the rolling mill main drive motor current change amount is less than 5%, it is determined that winding roll will not occur; (2) to control the rolling mill screw down cylinder piston moving speed, control the fast opening speed adjusting valve to make the piston moving speed 100±5mm / s, the hydraulic system fast opening response time control is 0.28-0.35s; (3) through the rolling mill main drive motor current and speed change amount over limit judgment, 0.2-0.6s in advance alarm strip break and winding roll.

2. The twenty-roller mill strip break and winding prediction control method according to claim 1, characterized in that, The judgment as normal rolling process includes that the tension has been established, there is strip steel in the rack, the tension control mode is roll gap adjustment control, and the rolling mill speed is greater than the limit speed.

3. The twenty-roller mill break and wind-up roll estimation control method according to claim 2, characterized by, The tension has been established by confirming that the actual value of the tension is greater than the minimum tension value, and the minimum tension value is 10±2% of the set tension.

4. The twenty-roller mill break and roll wrapping estimation control method according to claim 2, characterized by, The limit speed is 60±3m / min.

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