A control method for leveling a coiling pinch roll according to a center line deviation of a finishing mill tail

Abstract

The application relates to a control method of a hot rolling coiler, in particular to a control method of leveling a coiling pinch roll according to a center line deviation of a finishing mill tail part. The center line deviation of the finishing mill tail part is judged, the pinch roll pressure or roll gap leveling amount is calculated according to the judgment result of the center line deviation of the finishing mill tail part, the strip steel thickness, width and hardness group are combined, the working side pinch roll pressure or roll gap is automatically compensated on the basis of the original control through a program to calculate the leveling pressure or roll gap, the pressure or roll gap of the working side pinch roll is increased or decreased, the automatic leveling function of the pinch roll tail part is realized, and the control method of leveling the coiling pinch roll according to the center line deviation of the finishing mill tail part adjusts the pinch roll pressure or roll gap in real time through the center line deviation of the finishing mill tail part, the strip steel tail part deviation is corrected, so that the purpose of controlling the coiling quality is achieved.

Description

Technical Field

[0001] This invention relates to a control method for a hot rolling coiler, and more particularly to a control method for leveling the coiling pinch rolls based on the deviation of the centerline at the tail of the finishing mill. Background Technology

[0002] With the advancement of industrial technology, the role of coilers is to coil rolled finished products into coils to meet the needs of production, transportation, storage, and users. Coilers have high tension to ensure reduced rolling pressure and minimize strip warping, thereby improving the quality of strip products. Coilers generally consist of core equipment such as the coil shaft and auxiliary coiling equipment such as the coiling rollers. During the product coiling process, the product is mainly formed on the coil shaft, which is generally driven by a motor. The auxiliary coiling equipment, the coiling rollers, is also generally driven by a motor to rotate, and a fluid hydraulic cylinder drives the movement of the coiling rollers to help with smooth coiling.

[0003] Currently, coiling is the final process in the hot rolling main line, and coil shape is an important control indicator in this area. The most common and difficult-to-control defective coil shape is the tail overflow of the steel coil. The tail overflow is caused by the steel strip deviating. The side guide plate forces the deviation, forming an arc path. During the rolling process, the steel strip does not return to the center line. After the steel strip loses tension at the tail, the deviation correction effect of the side guide plate disappears. The tail overflow is closely related to the degree of sickle bend of the strip tail after finishing rolling. The imbalance of rolling force on both sides of the finishing mill is the cause of the steel strip deviating.

[0004] After finishing rolling and strip polishing, when the strip tail has a severe camber, it often deviates to one side. The side guide plate's correction process and the strip's edge compression generate significant pressure. When this pressure exceeds the set pressure, the side guide plate gradually opens, resulting in severe overflow at the strip tail. Furthermore, during the deviance process after finishing rolling and strip polishing, even if the side guide plate effectively corrects the deviation and the strip does not shift outwards layer by layer, during the short stroke at the tail of the side guide plate's movement, although it opens according to the set opening degree, the camber at the strip tail causes compression to one side, resulting in severe overflow at the outer 1-2 turns.

[0005] By analyzing the overflow rate corresponding to different centerline deviations at the tail of the finishing mill (detection range of -200mm to 200mm), it was found that as the centerline deviation at the tail of the finishing mill increases, the overflow defect rate also gradually increases. When the centerline deviation at the tail of the finishing mill is greater than 60mm, the overflow defect rate increases significantly. The specific data are shown in Table 1 below.

[0006] Table 1 Correspondence between centerline deviation at the tail of the finishing mill and flash defects

[0007] Absolute value of centerline deviation at the tail of the finishing mill / mm Mean absolute value of centerline deviation at the tail of the finishing mill / mm Number of rolls / blocks of overflow sealing Total number of rolls produced / blocks Overflow rate 0-20 15 8 5406 0.15% 20-40 31 22 13028 0.17% 40-60 50 52 7436 0.70% 60-80 70 58 1894 3.06% 80-100 88 52 811 6.41% 100-120 111 43 321 13.40% 120-140 130 28 134 20.90% 140-160 154 21 50 42.00% 160-180 161 12 21 57.14% 180-200 186 8 12 66.67%

[0008] Currently, there are two control modes for the pinch rolls: pressure control (controlled according to the target pressure on one side) and position control (controlled according to the total target pressure). The two control modes can be selected and switched between each other. When the strip tail has a large camber after finishing rolling, if the pinch rolls use pressure control, the operator adjusts the pressure setting on the working side. If the pinch rolls use position control, the operator adjusts the roll gap on the working side to correct the deviation of the strip tail and improve the coil shape control. After the strip is coiled, the adjusted pressure setting or roll gap is canceled. This method has a certain improvement effect on coil shape control, but it increases the operator's workload.

[0009] The purpose of this invention is to provide a control method for leveling the coiling pinch rolls based on the deviation of the centerline at the tail of the finishing mill. This control method adjusts the pressure or roll gap of the pinch rolls in real time by adjusting the deviation of the centerline at the tail of the finishing mill, thereby correcting the deviation of the strip at the tail and achieving the purpose of controlling the coil shape quality. Summary of the Invention

[0010] To achieve the above objectives, this invention provides a control method for leveling the coiling pinch rolls based on the deviation of the centerline at the tail of the finishing mill. The strip coiling process of the coiling system consists of a finishing mill work roll, a laminar flow cooling roller table, rolled strip, a finishing mill centerline deviation detection device, a side guide plate, an upper pinch roll, a lower pinch roll, an auxiliary coiling roll, and a coiling drum. After the strip head is rolled by the finishing mill work roll, it is conveyed to the side guide plate by the laminar flow cooling roller table. A laminar flow cooling device is provided on the upper part of the laminar flow cooling roller table. The rolled strip is bent and guided by the upper and lower pinch rolls and runs to the coiling drum to coil the strip. The auxiliary coiling roll assists the coiling drum in coiling the strip.

[0011] After the steel is thrown from the last stand of the finishing mill, the centerline deviation of the finishing mill tail is detected by the finishing mill centerline deviation detection device. The average centerline deviation of the finishing mill within 200ms after the steel is thrown at F1 is taken as P1. The average centerline deviation of the finishing mill within 200ms before the signal of the finishing mill centerline deviation detection device at the finishing mill exit is taken as P2. The centerline deviation of the finishing mill tail is obtained by subtracting P1 from P2, thereby determining the centerline deviation of the finishing mill tail Pt.

[0012] The pinch roll pressure leveling amount △For is calculated by combining the centerline deviation Pt of the finishing mill tail, strip width W, strip thickness H, and strip hardness group. PR Or the leveling amount △Gap of the pinch roller gap PR .

[0013] If the pinching roll pressure is controlled, the leveling amount of the pinching roll pressure based on the difference in the center line of the finishing mill tail is:

[0014]

[0015] In the formula:

[0016] △For PR —Calculation of pinch roller pressure leveling (KN);

[0017] Pt—— Deviation of centerline at the tail of the finishing mill (mm).

[0018] W — Target width of strip rolling (mm);

[0019] H — Target thickness of strip rolling (mm);

[0020] hard – the hardness group of strip steel.

[0021] Wherein, a positive value of Pt indicates that the strip is actually biased towards the working side, and a negative value of Pt indicates that the strip is actually biased towards the transmission side. The pinch roll pressure leveling amount ΔFor PR A positive value indicates an increase in the working side set pressure (pressing the working side), and the pinch roller pressure leveling amount △For PR A negative value indicates a reduction in the working side set pressure (raising the working side).

[0022] If the pinch rolls are controlled by position, the leveling amount of the pinch roll gap based on the deviation of the centerline at the tail of the finishing mill is:

[0023]

[0024] In the formula:

[0025] △Gap PR —Calculation of leveling gap between pinch rolls (mm);

[0026] Pt—— Deviation of centerline at the tail of the finishing mill (mm).

[0027] W — Target width of strip rolling (mm);

[0028] H — Target thickness of strip rolling (mm);

[0029] hard – the hardness group of strip steel.

[0030] Wherein, a positive value of Pt indicates that the strip is actually biased towards the working side, and a negative value of Pt indicates that the strip is actually biased towards the transmission side, and the leveling amount of the pinch roll gap △Gap PR A positive value indicates an increase in the working side roll gap (lifting the working side), and the pinch roll pressure leveling amount △For PR A negative value indicates a reduction in the working side roll gap (pressing the working side).

[0031] Based on the determined pinch roller pressure leveling amount △For PR Or the leveling amount △Gap of the pinch roller gapPR Based on the original control, the pressure or gap of the working-side pinch rolls is adjusted by writing leveling commands into the control system. This achieves the purpose of automatically calculating and compensating for the leveling pressure or gap, increasing or decreasing the pressure or gap of the working-side pinch rolls, and realizing the automatic leveling function at the tail of the pinch rolls. When the strip pinch rolls throw out the steel, the pressure or gap of the working-side pinch rolls, which was compensated based on the original control, is restored.

[0032] Analysis revealed that when the centerline deviation at the tail of the finishing mill exceeds 60mm, the incidence of strip edge defects at the tail increases significantly. When the centerline deviation at the tail of the finishing mill is less than 60mm, the impact on the tail coil shape is relatively small. Therefore, the pre-leveling function of the pinch rolls is not used when the absolute value of the centerline deflection at the tail of the finishing mill is less than 60mm. To avoid overshooting caused by excessive pinch roll leveling, the pinch roll pressure leveling range is -6KN to 6KN. If the upper or lower limit is exceeded, the adjustment value is taken from the corresponding upper or lower limit value. The pinch roll gap leveling value range is -0.2mm to 0.2mm. If the upper or lower limit is exceeded, the adjustment value is taken from the corresponding upper or lower limit value. Based on the actual situation of the production line, the upper and lower limits of the pinch roll pressure or the gap leveling amount can be adjusted.

[0033] Based on the control method of adjusting the leveling of the pinch rolls according to the deviation of the center line at the tail of the finishing mill, this method can effectively improve the quality problem caused by the deviation of the strip tail after finishing milling. This method can realize automatic leveling control of the pinch rolls by combining the center line deviation of the finishing mill, reducing manual intervention and improving the level of automation. This method is simple and effective, and can significantly reduce the quality defects of the tail overflow, while improving the level of automation control, reducing production costs, and reducing the workload of manual labor. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and examples.

[0035] Figure 1 This is a flowchart of the processing method of the present invention.

[0036] Figure 2 This is a schematic diagram of the winding machine finishing mill of the present invention.

[0037] Figure 3 This is a schematic diagram of the strip tail offset pinch roll leveling method of the present invention.

[0038] Figure 2 In the middle: 1. Finishing work roll, 2. Layer cooling roll table, 3. Rolled strip, 4. Finishing center line deviation detection device, 5. Side guide plate, 6. Upper pinch roll, 7. Lower pinch roll, 8. Auxiliary roll, 9. Rolling drum. Detailed Implementation

[0039] Example 1:

[0040] After the steel is thrown from the last stand of the finishing mill, the centerline deviation of the finishing mill tail is detected by the finishing mill centerline deviation detection device. The average centerline deviation of the finishing mill within 200ms after the steel is thrown at F1 is taken as P1, and the average centerline deviation of the finishing mill centerline within 200ms before the signal of the finishing mill centerline deviation detection device at the finishing mill exit is taken as P2. The centerline deviation of the finishing mill tail is obtained by subtracting P1 from P2, and thus the centerline deviation of the finishing mill tail is determined as Pt.

[0041] The pinch roll pressure leveling amount △For is calculated by combining the centerline deviation Pt of the finishing mill tail, strip width W, strip thickness H, and strip hardness group. PR .

[0042] When the pinching is controlled by pressure, the pinching roll pressure leveling amount is based on the difference in center line between the finishing mill tail sections:

[0043]

[0044] In the formula:

[0045] △For PR —Calculation of pinch roller pressure leveling (KN);

[0046] Pt—— Deviation of centerline at the tail of the finishing mill (mm).

[0047] W — Target width of strip rolling (mm);

[0048] H — Target thickness of strip rolling (mm);

[0049] hard – the hardness group of strip steel.

[0050] Wherein, a positive value of Pt indicates that the strip is actually biased towards the working side, and a negative value of Pt indicates that the strip is actually biased towards the transmission side. The pinch roll pressure leveling amount ΔFor PR A positive value indicates an increase in the working side set pressure (pressing the working side), and the pinch roller pressure leveling amount △For PR A negative value indicates a reduction in the working side set pressure (raising the working side).

[0051] Based on the determined pinch roller pressure leveling amount △For PR Based on the original control, the working side pinch roll pressure is adjusted by writing a leveling command into the control system to achieve the purpose of automatically calculating the leveling pressure compensation, increasing or decreasing the pressure of the working side pinch roll, and realizing the automatic leveling function at the tail of the pinch roll. When the strip pinch roll throws the steel, the pressure of the working side pinch roll compensated on the original control basis is restored.

[0052] Meanwhile, to avoid unnecessary adjustments, the pre-leveling function of the pinch rolls is not used when the absolute value of the centerline deflection at the tail of the finishing mill is less than 60mm. To avoid overshooting caused by excessive pinch roll leveling, the pinch roll pressure leveling range is -6KN to 6KN. When the upper and lower limits are exceeded, the adjustment value is taken as the corresponding upper and lower limit values. The upper and lower limits of the pinch roll pressure leveling can be adjusted according to the actual situation of the production line.

[0053] Example 2:

[0054] After the steel is thrown from the last stand of the finishing mill, the centerline deviation of the finishing mill tail is detected by the finishing mill centerline deviation detection device. The average centerline deviation of the finishing mill within 200ms after the steel is thrown at F1 is taken as P1, and the average centerline deviation of the finishing mill centerline within 200ms before the signal of the finishing mill centerline deviation detection device at the finishing mill exit is taken as P2. The centerline deviation of the finishing mill tail is obtained by subtracting P1 from P2, thereby determining the centerline deviation of the finishing mill tail Pt.

[0055] The leveling amount △Gap of the pinch roll gap is calculated by combining the deviation of the center line at the tail of the finishing mill (Pt), the strip width (W), the strip thickness (H), and the strip hardness group (hard). PR .

[0056] When the pinch rolls are in position control mode, the leveling amount of the pinch roll gap based on the deviation of the centerline at the tail of the finishing mill is:

[0057]

[0058] In the formula:

[0059] △Gap PR —Calculation of leveling gap between pinch rolls (mm);

[0060] Pt—— Deviation of centerline at the tail of the finishing mill (mm).

[0061] W — Target width of strip rolling (mm);

[0062] H — Target thickness of strip rolling (mm);

[0063] hard – the hardness group of strip steel.

[0064] Wherein, a positive value of Pt indicates that the strip is actually biased towards the working side, and a negative value of Pt indicates that the strip is actually biased towards the transmission side, and the leveling amount of the pinch roll gap △Gap PR A positive value indicates an increase in the working side roll gap (lifting the working side), and the pinch roll pressure leveling amount △For PR A negative value indicates a reduction in the working side roll gap (pressing the working side).

[0065] Based on the determined leveling amount △Gap of the pinch roll gap PRBased on the original control, the leveling command is written into the control system to automatically calculate and level the gap of the working side pinch rolls, increase or decrease the gap of the working side pinch rolls, and realize the automatic leveling function at the tail of the pinch rolls. When the strip pinch rolls throw out the steel, the gap of the working side pinch rolls compensated on the original control basis is restored.

[0066] Meanwhile, to avoid unnecessary adjustments, the pre-leveling function of the pinch rolls is not activated when the absolute value of the centerline deflection at the tail of the finishing mill is less than 60mm. To avoid overshooting caused by excessive pinch roll leveling, the pinch roll gap leveling value range is -0.2mm to 0.2mm. When it exceeds the upper and lower limits, the adjustment value is taken as the corresponding upper and lower limit values. The upper and lower limits of the pinch roll gap leveling amount can be adjusted according to the actual situation of the production line.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent controls or modifications made according to the spirit and essence of the main technical solution of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A control method for leveling the coiling pinch rolls based on the deviation of the tail centerline of a finishing mill, characterized in that, Includes the following steps: When the steel is ejected from the finishing mill, the deviation Pt of the center line at the tail of the finishing mill is obtained; Based on the deviation of the center line of the finishing mill tail Pt, the strip width W, the strip thickness H, and the strip hardness group hard, calculate the pinch roll pressure leveling amount △ForPR or the pinch roll gap leveling amount △GapPR. Pressure leveling or roll gap leveling of the take-up pinch roll is performed by writing leveling instructions into the control system based on the original pressure or roll gap control. When the pressure control mode is used, the calculation formula for the pinch roller pressure leveling amount ΔForPR is as follows: ； When the position control mode is used, the formula for calculating the leveling amount △GapPR of the pinch roll gap is: ； A positive value for Pt indicates that the strip is actually biased towards the working side, while a negative value for Pt indicates that the strip is actually biased towards the transmission side; the △For PR A positive value indicates an increase in the working side set pressure, while a negative value indicates a decrease in the working side set pressure; the △Gap PR A positive value indicates an increase in the working side roll gap, while a negative value indicates a decrease in the working side roll gap.

2. The control method according to claim 1, characterized in that, The deviation Pt of the centerline at the tail of the finishing mill is determined in the following way: After the steel is thrown from the last stand of the finishing mill, the average deviation of the finishing mill centerline within 200ms after the steel is thrown by F1 is taken as P1, and the average deviation of the finishing mill centerline within 200ms before the signal of the finishing mill exit centerline deviation detection device is closed is taken as P2. The centerline deviation of the finishing mill tail is obtained by subtracting P1 from P2.

3. The control method according to claim 1, characterized in that, When the absolute value of the deviation Pt of the center line of the finishing mill tail is less than 60mm, the pressure leveling or roll gap leveling is not performed.

4. The control method according to claim 1, characterized in that, The pinch roller pressure leveling amount △For PR The range is from -6KN to 6KN. When the calculated value exceeds this range, the corresponding upper or lower limit value is taken.

5. The control method according to claim 1, characterized in that, The leveling amount △Gap of the pinch roller gap PR The range is from -0.2mm to 0.2mm. When the calculated value exceeds this range, the corresponding upper or lower limit value is taken.

6. The control method according to claim 1, characterized in that, The pressure leveling or roll gap leveling of the coiling pinch rolls is specifically as follows: based on the original pressure or roll gap control, a leveling command is written into the control system to automatically increase or decrease the pressure or roll gap of the working side pinch rolls; when the strip steel pinch rolls throw out the steel, the compensated pressure or roll gap is restored.

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