Method for dynamic correction of exit thickness set value of tandem cold rolling mill

Abstract

The application discloses a kind of dynamic correction methods of outlet thickness setting value of cold continuous rolling mill, comprising the following steps: S1, a group of S1 rack outlet thickness actual value is constantly collected, and the outlet thickness setting compensation coefficient k of S4 rack is calculated by the array of the outlet thickness actual value;S2, the compensation coefficient k is gradually transferred from the outlet thickness gauge position of the S1 rack to the roll gap position of the S4 rack by compensation coefficient information table;S3, the outlet thickness setting value of the S4 rack after compensation is calculated in the roll gap position of the S4 rack.The application dynamically adjusts the outlet thickness setting value of cold continuous rolling mill according to the abnormal fluctuation of S1 rack outlet thickness of cold rolling mill, which can not only ensure the thickness precision requirement of cold continuous rolling mill finished strip steel, but also ensure the flatness precision requirement of finished strip steel.

Description

Technical Field

[0001] This invention relates to cold rolling mill technology, and more specifically, to a method for dynamically correcting the exit thickness setting value of a cold rolling mill. Background Technology

[0002] Thickness accuracy is one of the most important quality indicators for cold-rolled strip steel. With the rise and development of industries such as automobiles, aviation, home appliances, precision instruments, civil construction, and canned food, there are strict requirements for the thickness accuracy of cold-rolled strip steel.

[0003] The cold rolling mill is one of the most complex, highly automated, and precision-critical pieces of equipment in the metallurgical industry, representing, to a certain extent, the level of technological development in the steel industry. A cold rolling mill typically has five stands arranged along the rolling direction (the direction of strip movement). Thickness control in the cold rolling mill is crucial for ensuring the accuracy of the finished cold-rolled strip thickness. To achieve precise thickness control, a thickness gauge must be installed. This gauge measures the thickness at the mill's inlet and outlet, and the thickness is controlled through a mill thickness algorithm.

[0004] A typical cold rolling mill uses five stands to roll strip from thick to thin. Thickness gauges are installed at the entrance and exit of stand S1 and stand S4, respectively. Thickness control of the strip in the cold rolling mill is achieved through thickness control algorithms for stands S1, S2, and S4. Traditional thickness control algorithms for cold rolling mills include... Figure 1 As shown. In Figure 1 In this process, the inlet and outlet thickness gauges of the S1 stand are used for the thickness control algorithms of the S1 and S2 stands, respectively. The thickness control algorithm of the S1 stand includes both feedforward and feedback control algorithms. The output of the S1 stand thickness control algorithm is an additional setpoint for the roll gap control of the S1 stand, eliminating the thickness deviation of the strip at the exit of the S1 stand by adjusting the roll gap. The thickness control algorithm of the S2 stand is a feedforward control algorithm, and its output is an additional setpoint for the roll gap control of the S2 stand. It eliminates the influence of the thickness deviation of the strip at the exit of the S1 stand on the thickness accuracy of the cold continuous rolling mill by adjusting the roll gap of the S2 stand. To ensure good strip shape of the finished strip, the control of the S5 stand uses rolling force control. Rolling force control cannot eliminate the strip thickness difference; therefore, the thickness deviation of the finished strip, i.e., the thickness deviation of the strip at the exit of the S5 stand, is eliminated by the roll gap control of the S4 stand.

[0005] Since the S5 rack essentially does not change the strip thickness, the exit thickness setting of the S4 rack is equal to that of the S5 rack. The exit thickness gauge of the S5 rack is used for thickness control calculations of the S4 rack, and the thickness control algorithm of the S4 rack is a feedback control algorithm.

[0006] In traditional cold rolling mill thickness control algorithms, abnormal thickness deviations in finished strip detected by the thickness gauge at the exit of the S5 stand are eliminated through the thickness control algorithm of the S4 stand. However, this algorithm suffers from significant lag. Due to the limitations of traditional cold rolling mill thickness control algorithms, and the fact that abnormal thickness deviations in finished strip are generally caused by abnormal thickness deviations at the exit of the S1 stand, this algorithm is less effective.

[0007] In existing patent applications, such as Chinese patent applications No. 200910196647.5 and 201510253421.X, methods for directly and indirectly detecting strip steel performance are used respectively, but both patents use the performance test values ​​for thickness control.

[0008] For example, Chinese patent application No. 201510253421.X extends the entry thickness deviation of the S2 frame to feedforward thickness control of the S3 and S4 frames. Chinese patent application No. 201610997706.9 uses the detection values ​​of a laser velocimeter and a thickness gauge to control thickness deviation. Chinese patent application No. 201610286478.4 uses the entry thickness deviation of the S2 frame to predict the thickness deviation of the S3 and S4 frames, and uses the predicted thickness deviation to adjust the roll gap value, thereby eliminating thickness deviation. However, none of the above patented technologies consider the impact of abnormal thickness deviation on thickness control accuracy.

[0009] For example, Chinese patent applications 200910057469.8 and 200810039445.5 proposed methods for calculating the thickness setting value of each rack outlet, but did not consider methods for eliminating thickness deviations. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a dynamic correction method for the exit thickness setting value of a cold rolling mill. Based on the abnormal fluctuations in the exit thickness of the S1 stand of the cold rolling mill, the exit thickness setting value of the cold rolling mill is dynamically adjusted, which can not only ensure the thickness accuracy requirements of the finished strip steel, but also ensure the shape accuracy requirements of the finished strip steel.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A method for dynamically correcting the exit thickness setting value of a cold rolling mill includes the following steps:

[0013] S1. Continuously collect a set of actual exit thickness values ​​of frame S1, and calculate the compensation coefficient k of the exit thickness of frame S4 ​​through the array of actual exit thickness values.

[0014] S2. The compensation coefficient k is gradually transferred from the exit thickness gauge position of the S1 frame to the roll gap position of the S4 frame through the compensation coefficient information table.

[0015] S3. Calculate the output thickness setting value of the S4 frame after compensation at the roll gap position of the S4 frame.

[0016] Preferably, in step S1, the calculation of the compensation coefficient k is as follows:

[0017] S11. Set the upper limit value of the exit thickness of the S1 frame to h. 1U The lower limit of the export thickness is h. 1L ;

[0018] S12. Save the actual thickness value collected by the thickness gauge at the exit of the S1 frame to array h. 1_act [n], where n represents the array value;

[0019] S13, Calculate the array h 1_act The maximum value in [n], h 1_max =max(h 1_act [0],h 1_act [1],…,h 1_act [n-1]);

[0020] S14. Calculate the array h 1_act The minimum value in [n], h 1_min =min(h) 1_act [0],h 1_act [1],…,h 1_act [n-1]);

[0021] S15. Calculate the maximum value h. 1_max With the upper limit value h 1U The difference between them, the upper limit deviation h 1U_dev =h 1_max -h 1U If the upper limit deviation is greater than zero, it means that the actual thickness exceeds the upper limit of the exit thickness of the S1 frame.

[0022] S16. Calculate the minimum value h. 1_min With the lower limit value h 1L The difference between them, the lower limit deviation h 1L_dev =h 1_min -h 1L If the value of the lower limit deviation is less than zero, it means that the actual thickness value exceeds the lower limit value of the exit thickness of the S1 frame;

[0023] S17. Calculate the compensation coefficient k for the outlet thickness setting of the S4 frame based on the upper limit deviation and the lower limit deviation:

[0024] When h 1U_dev>0.0 and h 1L_dev When < 0.0, k = 0.0;

[0025] When h 1U_dev <0.0 and h 1L_dev When k > 0.0, k = 0.0;

[0026] When h 1U_dev >0.0 and h 1L_dev When >0.0:

[0027] When h 1U_dev <h 1L_dev At that time, k = -w1 × h 1U_dev ;

[0028] When h 1U_dev >h 1L_dev At that time, k = -w1 × h 1L_dev ;

[0029] Where w1 is the gain coefficient that the actual thickness value exceeds the upper limit of the outlet thickness of the S1 frame;

[0030] When h 1U_dev <0.0 and h 1L_dev When <0.0:

[0031] When h 1U_dev >h 1L_dev At that time, k = -w² × h 1U_dev ;

[0032] When h 1U_dev <h 1L_dev At that time, k = -w² × h 1L_dev ;

[0033] Where w2 is the gain coefficient that the actual thickness value exceeds the lower limit of the outlet thickness of the S1 frame.

[0034] Preferably, in step S2, the compensation coefficient information table is used to store, move, and retrieve the compensation coefficient k, and the movement of the compensation coefficient k within different compensation coefficient information is triggered by the pulse counter signals on the work rollers of the S2 frame, S3 frame, and S4 frame, respectively.

[0035] Preferably, in step S3, after calculating and compensating for the roll gap position of the S4 frame, the exit thickness setting value h of the S4 frame is... 4_set The calculation formula is as follows:

[0036] h 4_set =h 4_set_i ×(1+k)

[0037] Wherein, is the initial thickness setting value of the exit of the S4 stand, which is calculated and output by the cold rolling mill model system.

[0038] This invention provides a method for dynamically correcting the exit thickness setting value of a cold rolling mill, which dynamically adjusts the exit thickness setting value of the cold rolling mill. Using this method, the limitations of the 4-stand thickness control algorithm can be overcome, ensuring not only the thickness accuracy requirements of the finished strip from the cold rolling mill but also the strip shape accuracy requirements. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the algorithm for thickness control in a traditional cold rolling mill;

[0040] Figure 2 This is a schematic diagram of the algorithm for the dynamic correction method of the exit thickness setting value of the cold continuous rolling mill of the present invention;

[0041] Figure 3 This is a schematic diagram illustrating the storage, movement, and extraction of compensation coefficient information in the dynamic correction method for the exit thickness setting value of the cold continuous rolling mill of the present invention. Detailed Implementation

[0042] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0043] Combination Figure 2 As shown, the present invention provides a dynamic correction method for the exit thickness setting value of a cold rolling mill. Due to the change in the exit thickness setting value of the cold rolling mill (i.e., the exit thickness setting of the S4 stand), the roll gap size of the S4 stand can be changed through the thickness control algorithm of the S4 stand. The roll gap adjustment of the S4 stand can eliminate abnormal thickness deviations in the finished strip at the exit of the cold rolling mill. Specifically, the method includes the following steps:

[0044] S1. Continuously collect a set of actual exit thickness values ​​for rack S1. Calculate the compensation coefficient k for the exit thickness of rack S4 using the array of actual exit thickness values. The specific algorithm is as follows:

[0045] S11. Set the upper limit value of the exit thickness of frame S1 to h. 1U The lower limit of the export thickness is h. 1L ;

[0046] S12. Save the actual thickness value collected by the thickness gauge at the exit of frame S1 to array h. 1_act [n], where n represents the array value;

[0047] S13, Calculate array h 1_act The maximum value in [n], h 1_max=max(h 1_act [0],h 1_act [1],…,h 1_act [n-1]);

[0048] S14, Calculate array h 1_act The minimum value in [n], h 1_min =min(h) 1_act [0],h 1_act [1],…,h 1_act [n-1]);

[0049] S15. Calculate the maximum value h. 1_max With upper limit value h 1U The difference between them, the upper limit deviation h 1U_dev =h 1_max -h 1U If the upper limit deviation is greater than zero, it means that the actual thickness exceeds the upper limit of the exit thickness of the S1 frame.

[0050] S16. Calculate the minimum value h. 1_min With the lower limit value h 1L The difference between them, the lower limit deviation h 1L_dev =h 1_min -h 1L If the lower limit deviation is less than zero, it means that the actual thickness value exceeds the lower limit of the exit thickness of the S1 frame.

[0051] S17. Calculate the compensation coefficient k for the exit thickness setting of frame S4 ​​based on the upper and lower limit deviations:

[0052] When h 1U_dev >0.0 and h 1L_dev When < 0.0, k = 0.0;

[0053] When h 1U_dev <0.0 and h 1L_dev When k > 0.0, k = 0.0;

[0054] When h 1U_dev >0.0 and h 1L_dev When >0.0:

[0055] When h 1U_dev <h 1L_dev At that time, k = -w1 × h 1U_dev ;...... ...

[0057] When h 1U_dev >h 1L_dev At that time, k = -w1 × h 1L_dev ;

[0058] Where w1 is the gain coefficient that the actual thickness value exceeds the upper limit of the exit thickness of frame S1, and the value range is 0 to 6;

[0059] When h 1U_dev <0.0 and h 1L_dev When <0.0:

[0060] When h 1U_dev >h 1L_dev At that time, k = -w² × h 1U_dev ;

[0061] When h 1U_dev <h 1L_dev At that time, k = -w² × h 1L_dev ;

[0062] Where w2 is the gain coefficient that the actual thickness value exceeds the lower limit of the outlet thickness of frame S1, and the value range is 0 to 10.

[0063] S2. The compensation coefficient k is progressively transferred from the exit thickness gauge position of frame S1 to the roll gap position of frame S4 ​​via the compensation coefficient information table. At the roll gap position of frame S4, the compensation coefficient k set for the exit thickness of frame S4 ​​is output. The compensation coefficient information table is used for saving, moving, and retrieving the compensation coefficient k (e.g., ...). Figure 3 As shown, the movement of the compensation coefficient k within different compensation coefficient information is triggered by the pulse counter signals on the work rollers of frames S2, S3 and S4 respectively.

[0064] S3. Calculate the compensation value h of the exit thickness of the S4 frame at the roll gap position. 4_set The calculation formula is as follows:

[0065] h 4_set =h 4_set_i ×(1+k)

[0066] Among them, the initial thickness setting value at the exit of the S4 stand is calculated and output by the cold rolling mill model system.

[0067] Ultimately, this will eliminate abnormal thickness fluctuations at the exit of the cold rolling mill.

[0068] Example 1

[0069] This embodiment 1 describes a dynamic correction method for the exit thickness setting value of the thickness control system of a 5-stand six-roll CVC mill. For a strip with a thickness of 4.03 mm rolled to a thickness of 0.732 mm using a cold continuous rolling mill, the exit thickness setting values ​​for stands S1, S2, and S3 are 2.6 mm, 1.63 mm, and 1.1 mm, respectively. The initial exit thickness setting value for stand S4 is 0.732 mm, and the upper limit value h for the exit thickness setting of stand S1 is... 1UThe minimum thickness setting for the S1 rack exit is 2.7mm. 1L For a thickness of 2.5mm, the gain coefficient w1 = 0.3 when the thickness exceeds the upper limit, and the gain coefficient w2 = 0.3 when the thickness exceeds the lower limit. The specific steps are as follows:

[0070] (1) A set of actual values ​​h of the outlet thickness of S1 frame were collected. 1_act

[10] is [2.61, 2.62, 2.58, 2.63, 2.62, 2.59, 2.61, 2.64, 2.59, 2.9];

[0071] (2) Maximum thickness value h 1_max =2.9mm;

[0072] (3) Minimum thickness value h 1_min =2.58mm;

[0073] (4) Upper limit deviation h 1U_dev =2.9 - 2.7 = 0.2 mm;

[0074] (5) Lower limit deviation h 1L_dev =2.58 - 2.5 = 0.08 mm;

[0075] (6) Due to h 1U_dev >0.0 and h 1L_dev >0.0 and h 1U_dev <h 1L_dev S4 rack outlet thickness compensation coefficient k = -w1×h 1L_dev = -0.3 × 0.08 = 0.024;

[0076] (7) Transfer the S4 frame exit thickness compensation coefficient k to the S4 frame roll gap position through the compensation coefficient information table.

[0077] (8) Calculate the compensated S4 rack exit thickness setting h 4_set =h 4_set_i ×(1+k)=0.732×(1-0.024)=0.732×0.976=0.7144mm;

[0078] (9) Set the S4 rack outlet thickness to h 4_set Used for S4 rack thickness control algorithm.

[0079] Example 2

[0080] This embodiment 2 describes a dynamic correction method for the exit thickness setting value of the thickness control system of a 5-stand six-roll CVC mill. For a 4.03mm thick strip rolled to a thickness of 0.732mm using a cold continuous rolling mill, the exit thickness setting values ​​for stands S1, S2, and S3 are 2.6mm, 1.63mm, and 1.1mm, respectively. The initial exit thickness setting value for stand S4 is 0.732mm, and the upper limit value h for the exit thickness setting of stand S1 is... 1U The minimum thickness setting for the S1 rack exit is 2.7mm. 1L For a thickness of 2.5mm, the gain coefficient w1 = 0.3 when the thickness exceeds the upper limit, and the gain coefficient w2 = 0.3 when the thickness exceeds the lower limit. The specific steps are as follows:

[0081] (1) A set of actual values ​​h of the outlet thickness of S1 frame were collected. 1_act

[10] is [2.62, 2.31, 2.58, 2.62, 2.62, 2.59, 2.61, 2.63, 2.59, 2.61];

[0082] (2) Calculate the maximum thickness value h 1_max =2.63mm;

[0083] (3) Calculate the minimum thickness value h 1_min =2.31mm;

[0084] (4) Calculate the upper limit deviation h 1U_dev =2.63 - 2.7 = -0.07 mm;

[0085] (5) Calculate the lower limit deviation h 1L_dev =2.31 - 2.5 = -0.19 mm;

[0086] (6) Because when h 1L_dev <0.0 and h 1U_dev <0.0 and h 1U_dev >h 1L_dev S4 rack outlet thickness compensation coefficient k = -w2×h 1U_dev = -0.3 × (-0.07) = 0.021;

[0087] (7) Transfer the S4 frame exit thickness compensation coefficient k to the S4 frame roll gap position through the compensation coefficient information table.

[0088] (8) Calculate the compensated S4 rack exit thickness setting h 4_set =h 4_set_i ×(1+k)=0.732×(1+0.021)=0.732×1.021=0.747mm;

[0089] (9) Set the S4 rack outlet thickness to h 4_set Used for S4 rack thickness control algorithm.

[0090] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method of dynamically correcting an exit thickness set value of a tandem cold rolling mill, characterized by, The method comprises the following steps: S1, continuously collecting a group of actual outlet thickness values of the S1 stand, and calculating a compensation coefficient k of the outlet thickness setting of the S4 stand through an array of the actual outlet thickness values; S2, gradually transferring the compensation coefficient k from the outlet thickness gauge position of the S1 stand to the roll gap position of the S4 stand through a compensation coefficient information table; S3, calculating the outlet thickness setting value of the S4 stand after compensation at the roll gap position of the S4 stand, In the step S1, the compensation coefficient k is calculated as follows: S11, set the upper limit value of the exit thickness of the S1 rack as h 1U , and the lower limit value of the exit thickness as h 1L ; S12, save the thickness actual value collected by the exit thickness gauge of the S1 rack to array h 1_act [n], wherein n represents array value; S13, compute the array h 1_act max value in [n], h 1_max = max(h 1_act [0], h 1_act [1],..., h 1_act [n-1]); S14, compute the array h 1_act min in [n], h 1_min = min(h 1_act [0], h 1_act [1],..., h 1_act [n-1]); S15, calculating the maximum value h 1_max the difference between the maximum value h 1U upper limit deviation h 1U_dev = h 1_max - h 1U If the value of the upper limit deviation is greater than zero, it indicates that the actual thickness value exceeds the upper limit value of the outlet thickness of the S1 stand. S16, calculating the minimum value h 1_min the difference between the lower limit value h 1L h 1L_dev = h 1_min - h 1L , if the value of the lower limit deviation is less than zero, it indicates that the actual thickness value exceeds the lower limit value of the outlet thickness of the S1 stand; S17, calculating the compensation coefficient k of the outlet thickness setting of the S4 stand based on the upper limit deviation and the lower limit deviation: When h 1U_dev > 0.0 and h 1L_dev < 0.0, k = 0.0; when h 1U_dev <0.0 and h 1L_dev >0.0, k = 0.0; When h 1U_dev > 0.0 and h 1L_dev > 0.0: When h 1U_dev < h 1L_dev , k = -w1xh 1U_dev ; When h 1U_dev > h 1L_dev , k = -w1xh 1L_dev ; Wherein, w1 is a gain coefficient of the actual thickness value exceeding the upper limit value of the outlet thickness of the S1 stand, and the value range is 0-6; When h 1U_dev <0.0 and h 1L_dev <0.0: When h 1U_dev > h 1L_dev , k = -w2xh 1U_dev ; When h 1U_dev < h 1L_dev , k = -w2xh 1L_dev ; Wherein, w2 is a gain coefficient of the actual thickness value exceeding the lower limit value of the outlet thickness of the S1 stand, and the value range is 0-10.

2. The method of dynamically correcting the exit thickness set value of a tandem cold rolling mill according to claim 1, characterized in that, In the step S2, the compensation coefficient information table is used for saving, moving and extracting the compensation coefficient k, and the movement of the compensation coefficient k in the compensation coefficient information table is triggered by the pulse counter signals on the work rolls of the S2 stand, the S3 stand and the S4 stand, respectively.

3. The method of dynamically correcting the exit thickness set value of a tandem cold rolling mill according to claim 2, characterized in that, The step S3, the outlet thickness set value h of the S4 rack after the compensation of the roll gap position of the S4 rack is calculated 4_set The calculation formula is as follows: h 4_set = h 4_set_i x (1 + k) Wherein, is the initial outlet thickness setting value of the S4 stand, which is calculated and output by a cold continuous rolling mill model system.

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