Operation method for strip steel deviation control based on CSP process

Abstract

The invention discloses an operation method for strip steel deviation control based on a CSP process, which realizes stable rolling of the CSP process, improves the plate shape and coil shape quality, avoids the influence of steel piling accidents, product degradation and poor plate shape and coil shape on the subsequent process through side guide plate setting, roller convexity adjustment, friction force control and tension adjustment, effectively reduces the production cost, and improves the production efficiency. The problems of unstable rolling, poor asymmetric plate shape, poor coil shape and the like are solved.

Description

Technical Field

[0001] The invention belongs to the field of hot strip steel rolling, and in particular relates to an operating method for controlling strip steel deviation based on a CSP process. Background Art

[0002] The CSP thin slab continuous casting and rolling process is a short-process strip steel production process for producing hot-rolled coils that was successfully developed in the late 1980s and early 1990s. CSP (Compact Strip Production) is a compact hot strip process. The entire CSP process of Jiugang was designed by SMS-Demug of Germany and is the second-generation CSP technology. The equipment of its production line mainly consists of roller-bottom tunnel furnace, shear front side guide, hydraulic emergency shear, descaling machine, 6-stand four-roller finishing mill, laminar cooling device, 2 down coilers and other equipment. The thickness of the hot-rolled slab produced is 52-70mm, the strip width is 850mm-1680mm, the strip thickness is 1.2mm-18mm, and the maximum coil weight is 31t. Compared with the traditional continuous casting-cooling, cleaning-heating, rolling process, the continuous casting and rolling process has the advantages of short production cycle, less fixed asset investment, high metal recovery rate, good steel performance, and low energy consumption.

[0003] Due to objective factors in the actual production process, such as changes in the no-load roll gap of the rolling mill (including eccentricity, wear and thermal expansion of the rolls), fluctuations in rolling force (including fluctuations in incoming material thickness, changes in tension, fluctuations in incoming material composition, changes in rolling temperature and rolling speed, etc.), changes in the longitudinal stiffness of the rolling mill and changes in the oil film thickness of the support roll bearings, strip deviation during the rolling process becomes a normal phenomenon.

[0004] Strip deviation will lead to poor plate shape and is one of the direct causes of unilateral wave shape. During the rolling of thick specifications, strip deviation will lead to excessive wedge shape and quality defects such as staggered layers after coiling. During the rolling of thin specifications, strip deviation will lead to substandard plate shape, tail swing failure, tower shape, tail overflow and other coil defects after coiling. Severe deviation will lead to scrap steel due to failure of strip threading in the rolling mill, piled steel due to rolling process, and piled steel due to failure of strip threading in the coiler.

[0005] With the continuous expansion of the variety and specification range of cold-rolled, galvanized and hot-dip galvanized products, higher requirements are put forward for the plate shape, coil shape and thin-gauge rolling stability of hot-rolled products. If the strip runs out of control, it will inevitably lead to an increase in the accident rate of the production line, the product defect rate, and the labor intensity of workers, which is extremely unfavorable to the current extreme cost control of enterprises.

[0006] In order to solve the above problems, an operating method based on strip deviation control in Jiugang CSP process is invented. Summary of the invention

[0007] The purpose of the present invention is to provide an operating method for strip deviation control based on Jiugang CSP process to solve the problems of unstable rolling, poor asymmetric plate shape, poor coil shape, etc.

[0008] To achieve the above object, the present invention adopts the following technical solution: An operation method based on the CSP process strip deviation control, taking the production of Q235B*1250mm as an example, includes the following steps: A. Side guide setting: (1) The additional values ​​of the opening of the strip head, strip body and strip tail before shearing follow the principle of small, large and small, so as to keep the slab head centered when entering the F1 mill entrance side guide; (2) Side guide setting for F1-F6 rolling mills: Based on the free width of the slab head, the three conditions of smooth mill biting, stable rolling and tail casting are fully considered. The additional values ​​of the opening of the strip head, strip body and strip tail of the F1-F2-F3 rolling mills follow the principle of large, small, and large. The side guide setting for F4-F5-F6 rolling mills follows the principle of keeping the additional values ​​of the strip head and strip body consistent and increasing the additional value of the strip tail opening. The side guide setting for F1-F6 rolling mills follows the principle of increasing in sequence. The details are as follows: Table 1 B. Roll gap crown adjustment of rolling mill: During the thin-gauge rolling process, the self-stabilizing roll gap of the strip is formed by setting the CVC roll shifting parameters; (1) As the rolling thickness decreases, the cooling water volume of the working rolls of each stand is increased to reduce the thermal crown of the working rolls; the cooling water volume of the working rolls is set as shown in Table 2: Table 2 (2) When rolling thin slabs with a thickness of 2.0-1.5 mm, on the one hand, the reduction rate of each stand is strictly controlled, and on the other hand, the optimal CVC parameters are achieved through manual intervention or optimization of the secondary plate shape model constants; the reduction rate distribution and CVC parameters for thickness 2.0-1.5 mm are shown in Tables 3 and 4: Table 3 Table 4 (3) When rolling ≤2.0mm, the crown is set to 45-50μm; C. Friction control: Increase the surface roughness of the working roll during rolling to eliminate the risk of slipping and deviation; Before rolling thin-gauge products, the working roll grinding process is required to be as follows: F1-F2 roughness 1.0~1.6μm, F3-F4 roughness 0.9~1.3μm, F5-F6 roughness 0.4~0.6μm, and the roughness deviation between each point is less than 0.2μm; D. Adjustment of tension system; (1) Reduce the lifting resistance of the looper; when the rolling mill is unloaded, observe the supporting force of the loopers of each frame and judge that it should be within the range of 13±3kN; (2) Control the lifting angle of the looper at the moment of threading; by correcting the speed parameters and tension parameters, the lifting angle of the looper at the moment of threading is controlled within 34°; (3) As the rolling thickness decreases, the width increases, and the deformation resistance increases, the tension parameter settings of the F1-F6 rolling mills increase accordingly, as shown in Table 5: Table 5 (4) When producing strip steel ≤2.5 mm, the tension of the coiler is reduced by 50% after the tail of the F3 frame is discarded; (5) The unloading condition of the rolling mill is set to that the actual rolling force is 35% lower than the process setting value. The timing of closing the looper control during tail casting shall not be earlier than 0.3s earlier than the unloading timing of the corresponding frame.

[0009] The beneficial effects of the present invention are: achieving stable rolling and plate and coil quality in the CSP process, avoiding steel pile accidents, product degradation, and the impact of poor plate and coil shapes on subsequent processes, and effectively reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 These are photos of the strip head entering the rolling mill guide before and after the process of the present invention is implemented. DETAILED DESCRIPTION

[0011] The present invention is further described in detail below in conjunction with specific implementation modes.

[0012] An operation method based on the CSP process strip deviation control, taking the production of Q235B*1250mm as an example, includes the following steps: A. Side guide setting: (1) The additional values ​​of the opening of the strip head, strip body and strip tail before shearing follow the principle of small, large and small, so as to keep the slab head centered when entering the F1 mill entrance side guide; (2) Side guide setting for F1-F6 rolling mills: Based on the free width of the slab head, the three conditions of smooth mill biting, stable rolling and tail casting are fully considered. The additional values ​​of the opening of the strip head, strip body and strip tail of the F1-F2-F3 rolling mills follow the principle of large, small, and large. The side guide setting for F4-F5-F6 rolling mills follows the principle of keeping the additional values ​​of the strip head and strip body consistent and increasing the additional value of the strip tail opening. The side guide setting for F1-F6 rolling mills follows the principle of increasing in sequence. The details are as follows: Table 1 (3) Side guide setting when the rolling mill is idling: The additional value parameter setting of the side guide of the rolling mill to be idling should be increased by 20mm on the original basis, leaving a margin for the slab to pass smoothly through the rolling mill to be idling. The additional 20mm of the idling stand is set automatically by the first level. For example, the side guide setting of the idling F3 stand is as shown in Table 2: Table 2 B. Roll gap crown adjustment of rolling mill: During the thin-gauge rolling process, the self-stabilizing roll gap of the strip is formed by setting the CVC roll shifting parameters; (1) As the rolling thickness decreases, the cooling water volume of the working rolls of each stand is increased to reduce the thermal crown of the working rolls; the cooling water volume of the working rolls is set as shown in Table 3: Table 3 (2) When rolling thin slabs with a thickness of 2.0-1.5 mm, on the one hand, the reduction rate of each stand is strictly controlled, and on the other hand, the optimal CVC parameters are achieved through manual intervention or optimization of the secondary plate shape model constants; the reduction rate distribution and CVC parameters for thickness 2.0-1.5 mm are shown in Tables 4 and 5: Table 4 Table 5 (3) When rolling ≤2.0mm, the crown is set to 45-50μm; C. Friction control: Increase the surface roughness of the working roll during rolling to eliminate the risk of slipping and deviation; Before rolling thin-gauge products, the grinding process of the working rolls is required to be as follows: the roughness of F1-F2 is 1.0~1.6μm, the roughness of F3-F4 is 0.9~1.3μm, and the roughness of F5-F6 is 0.4~0.6μm, and the roughness deviation between each point is less than 0.2μm; before rolling the products, the roughness of the working rolls on the machine is confirmed, and the confirmation method includes precise measurement using a roughness meter and comparison with a standard sample; D. Adjustment of tension system; (1) Reduce the lifting resistance of the looper; when the rolling mill is unloaded, observe the supporting force of the loopers of each frame and judge that it should be within the range of 13±3kN; (2) Control the lifting angle of the looper at the moment of threading; by correcting the speed parameters and tension parameters, the lifting angle of the looper at the moment of threading is controlled within 34°; (3) As the rolling thickness decreases, the width increases, and the deformation resistance increases, the tension parameter settings of the F1-F6 rolling mills increase accordingly, as shown in Table 6: Table 6 (4) When producing strip steel ≤2.5 mm, the tension of the coiler is reduced by 50% after the tail of the F3 frame is discarded.

[0013] (5) The unloading condition of the rolling mill is set to that the actual rolling force is 35% lower than the set value. The timing of closing the looper control during tail casting shall not be earlier than 0.3s earlier than the unloading timing of the corresponding frame.

[0014] Beneficial effects after implementation: Figure 1 As shown, before the process is implemented ( Figure 1 (above) During the threading process, the head of the strip enters the rolling mill guide and deviates significantly. After the process is implemented ( Figure 1 (bottom) During the strip threading process, the head is aligned with the rolling mill guide; the CSP process achieves stable rolling and plate and coil quality, avoids steel pile accidents, product degradation, and the impact of poor plate and coil shape on subsequent processes, effectively reducing production costs.

Claims

1. An operating method based on CSP process strip deviation control, characterized in that: Taking the production of Q235B*1250mm as an example, the following steps are included: A. Side guide setting: (1) The additional values ​​of the opening of the strip head, strip body and strip tail before shearing follow the principle of small, large and small, so as to keep the slab head centered when entering the F1 mill entrance side guide; (2) Side guide setting for F1-F6 rolling mills: Based on the free width of the slab head, the three conditions of smooth mill biting, stable rolling and tail casting are fully considered. The additional values ​​of the opening of the strip head, strip body and strip tail of the F1-F2-F3 rolling mills follow the principle of large, small, and large. The side guide setting for F4-F5-F6 rolling mills follows the principle of keeping the additional values ​​of the strip head and strip body consistent and increasing the additional value of the strip tail opening. The side guide setting for F1-F6 rolling mills follows the principle of increasing in sequence. The details are as follows: Table 1 B. Roll gap crown adjustment of rolling mill: During the thin-gauge rolling process, the self-stabilizing roll gap of the strip is formed by setting the CVC roll shifting parameters; (1) As the rolling thickness decreases, the cooling water volume of the working rolls of each stand is increased to reduce the thermal crown of the working rolls; the cooling water volume of the working rolls is set as shown in Table 2: Table 2 (2) When rolling thin slabs with a thickness of 2.0-1.5 mm, on the one hand, the reduction rate of each stand is strictly controlled, and on the other hand, the optimal CVC parameters are achieved through manual intervention or optimization of the secondary plate shape model constants; the reduction rate distribution and CVC parameters for thickness 2.0-1.5 mm are shown in Tables 3 and 4: Table 3 Table 4 (3) When rolling ≤2.0mm, the crown is set to 45-50μm; C. Friction control: Increase the surface roughness of the working roll during rolling to eliminate the risk of slipping and deviation; Before rolling thin-gauge products, the working roll grinding process is required to be as follows: F1-F2 roughness 1.0~1.6μm, F3-F4 roughness 0.9~1.3μm, F5-F6 roughness 0.4~0.6μm, and the roughness deviation between each point is less than 0.2μm; D. Adjustment of tension system; (1) Reduce the lifting resistance of the looper; when the rolling mill is unloaded, observe the supporting force of the loopers of each frame and judge that it should be within the range of 13±3kN; (2) Control the lifting angle of the looper at the moment of threading; by correcting the speed parameters and tension parameters, the lifting angle of the looper at the moment of threading is controlled within 34°; (3) As the rolling thickness decreases, the width increases, and the deformation resistance increases, the tension parameter settings of the F1-F6 rolling mills increase accordingly, as shown in Table 5: Table 5 (4) When producing strip steel ≤2.5 mm, the tension of the coiler is reduced by 50% after the tail of the F3 frame is discarded; (5) The unloading condition of the rolling mill is set to that the actual rolling force is 35% lower than the process setting value. The timing of closing the looper control during tail casting shall not be earlier than 0.3s earlier than the unloading timing of the corresponding frame.

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