A continuous rolling process for solving the instability of rolling state of an open rolling coil

Abstract

The application discloses a continuous rolling process for solving the instability of rolling state of an open rolling coil, and belongs to the technical field of hot continuous rolling. When planning roll replacement and maintenance, a heating furnace is left empty, so that the open rolling slab is in the third heating section of the heating furnace when stopping rolling; the average temperature of the open rolling coil is controlled within 1230±20 DEG C, and the average temperature of five passes is controlled within 1060±20 DEG C; the temperature difference of the slab is controlled within 30 DEG C by adjusting parameters; the grinding precision of the roll is ensured by the following steps: roll offline, uniform cooling, measurement of roll offline curve, flaw detection, rough grinding, measurement of post-grinding curve, fine grinding and measurement of post-grinding curve; the roundness is controlled within 0.005 mm, and the taper is controlled within 0.005 mm; different roll types are configured for different stands; and the deformation resistance coefficient is corrected when there is a deviation between the actual thickness and the calculated thickness of the product, and the deformation resistance coefficient is corrected according to the deviation value.

Description

Technical Field

[0001] This invention belongs to the field of hot continuous rolling technology, specifically relating to a continuous rolling process that solves the problem of unstable rolling state during the unrolling of coils on a rolling line. Background Technology

[0002] Uncoiling refers to the process of resuming rolling after the steel coil has been held at a certain temperature in the heating furnace during roll changes, maintenance, or a shutdown due to a malfunction. When the slab is near the exit gate of the soaking zone, uneven temperatures on the drive and operating sides lead to inconsistent deformation resistance and ductility on both sides of the slab. This can easily cause lateral bending during rolling on either side, making it difficult to adjust the slab shape. Furthermore, inconsistent holding times during uncoiling result in inconsistent slab temperatures, which can cause discrepancies between the mill's set parameters and actual rolling conditions. This can easily lead to slab shape defects during production, and in severe cases, scrap, affecting both quality and yield. Summary of the Invention

[0003] To address the technical problems existing in the prior art, this invention provides a continuous rolling process that solves the problem of unstable rolling state in the unrolled coil stage. By developing the rolling line temperature regime, roll grinding accuracy and roll shape control, and thickness self-learning model, the problem of unstable rolling state in the unrolled coil stage is solved.

[0004] The purpose of this invention is to provide a continuous rolling process that solves the problem of unstable rolling state in the initial rolling of a rolling line, comprising the following steps in sequence: slab storage, slab heating, high-pressure water descaling, rough rolling, flying shear head and tail cutting, finish rolling, laminar flow cooling, coiling, inspection and storage, and coil storage.

[0005] The following steps are performed during the slab heating process:

[0006] When planning roll changes or maintenance, leave space in the heating furnace so that the unrolled slab is in the third heating section of the heating furnace when rolling stops;

[0007] The average temperature of the unrolling coil is controlled within the range of 1230±20℃, and the average temperature of the five test passes is controlled within the range of 1060±20℃.

[0008] Slab temperature difference: By adjusting parameters, the temperature difference between the slab and the slab can be controlled within a range of 30℃;

[0009] During the finishing rolling process, the following steps are performed:

[0010] Roll grinding accuracy: Roll unloading, uniform cooling, measuring roll unloading curve, flaw detection, rough grinding, measuring post-grinding curve, fine grinding, measuring post-grinding curve, ensuring roll grinding accuracy, roundness controlled within 0.005mm, taper controlled within 0.005mm;

[0011] Configure the roll type according to different frames;

[0012] Corrected deformation resistance coefficient: When there is a deviation between the actual thickness and the calculated thickness of the product, the deformation resistance coefficient is corrected according to the deviation value.

[0013] Preferably, the parameters include burner injection pressure and empty coal.

[0014] Preferably, the roll profile configuration is as follows:

[0015]

[0016] Preferably, the formula for correcting the deformation resistance coefficient based on the deviation value is as follows:

[0017] S i+1 =S i (1-a)+S r *a;

[0018] In the formula, S i The deformation resistance coefficient is set for the i-th calculation; S r The feedback value set for the i-th time; S i+1 is the deformation resistance coefficient used for the (i+1)th setting calculation; a is the self-learning gain factor.

[0019] Preferably, a deformation resistance learning interval is set within a 3mm range, as follows:

[0020]

[0021] The advantages and positive effects of this invention are:

[0022] This invention improves the stability of the unrolled coil rolling process by developing the rolling line temperature regime, roll grinding accuracy and roll shape control, and thickness self-learning model. Detailed Implementation

[0023] To make the above-mentioned objectives, control system design, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] A continuous rolling process for solving the problem of unstable rolling state during the initial rolling of a rolling line comprises the following steps: slab warehousing → slab heating → high-pressure water descaling → rough rolling → flying shear head and tail trimming → finish rolling → laminar flow cooling → coiling → inspection and warehousing → coil warehousing.

[0025] This invention discloses a solution to the unstable rolling state of pre-rolling line uncoiling, belonging to the field of hot continuous rolling technology. The solution includes: S1, leaving space in the heating furnace; S2, heating regime; S3, slab temperature difference; S4, roll grinding accuracy; S5, roll shape configuration; and S6, thickness self-learning program. This application optimizes the heating furnace regime, roll grinding regime, roll shape configuration, and thickness self-learning coefficient to develop a reasonable production process for preventing unstable pre-rolling line uncoiling rolling state.

[0026] S1 heating furnace reserved space: When the roll is changed or maintenance is planned, the heating furnace is reserved space so that the unrolled slab is in the third heating section of the heating furnace when rolling is stopped, avoiding the influence of cold air from the furnace door at the furnace opening and ensuring the temperature uniformity of both sides of the slab.

[0027] S2 heating regime: The average temperature of the unrolled coil is controlled within the range of 1230±20℃, and the average temperature of the five test passes is controlled within the range of 1060±20℃.

[0028] S3, Slab temperature difference: By adjusting the burner injection pressure, air-coal ratio, etc., temperature uniformity is ensured and the temperature difference between slabs is controlled within 30℃.

[0029] S4. During the precision control process of roll grinding, the following steps shall be performed:

[0030] Roll grinding accuracy: Roll off the production line - uniform cooling - measuring the roll off the production line curve - flaw detection - rough grinding - measuring the post-grinding curve - fine grinding - measuring the post-grinding curve, ensuring the rolling accuracy, roundness controlled within 0.005mm, and taper controlled within 0.005mm;

[0031] S5. Roll configuration: The roll profile is rationally configured based on the deformation and load conditions of each stand. The roll profile scheme is as follows:

[0032] Table 1 shows the roll type schemes.

[0033]

[0034] S6, Thickness self-learning coefficient:

[0035] When calculating the loaded roll gap of each stand in the finishing mill based on the final product thickness, an important parameter in the model is the deformation resistance coefficient of the material. When there is a deviation between the actual thickness of the product measured by the thickness gauge and the calculated thickness, the model corrects the deformation resistance coefficient based on the deviation value.

[0036] S i+1 =S i (1-a)+S r *a

[0037] In the formula, S i—The deformation resistance coefficient used in the i-th calculation of the model;

[0038] S r —The feedback value set by the model for the i-th time;

[0039] S i+1 —The deformation resistance coefficient used for the (i+1)th setting calculation of the model;

[0040] a——Self-learning gain factor.

[0041] During production, the deformation resistance coefficient changes constantly with the continuous feedback of production data. The smaller the change, the more stable the production; the larger the change, the greater the deviation between the calculated set value and the actual value.

[0042] In actual production, the deformation resistance of the same steel grade varies with different thicknesses. The data on how the deformation resistance coefficient changes with thickness are as follows:

[0043] Table 2 shows the variation of deformation resistance coefficient with thickness.

[0044] Deformation resistance coefficient 4179.49 4136.33 4107.32 4088.95 4025.66 3988.63

[0045] After the current production plan is completed, the deformation resistance coefficient value after rolling the last strip will be used as the initial value for the next rolling plan. However, according to the rolling plan scheduling principle, the specifications rolled at the end of the plan are usually those thicker than 13mm, while the specifications produced at the beginning of the new plan are mostly products with a thickness of around 5mm. Therefore, the initial value of the deformation resistance coefficient is not suitable for the specifications at the start of production. The model calculation accuracy deviation is large, and the flow rate within the finishing mill is mismatched, causing waviness, rolling defects, and even steel piling accidents. Therefore, a deformation resistance learning interval is set according to a range of 3mm, as follows:

[0046] Table 3 shows the learning interval for deformation resistance set according to a 3mm range.

[0047] Deformation resistance coefficient Coefficient 1 Coefficient 2 Coefficient 3 Coefficient 4 Coefficient 5

[0048] After setting the learning interval, the deformation resistance coefficient changes relatively little during the rectification and learning process, which is closer to the actual deformation resistance coefficient value and improves the model calculation accuracy.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A continuous rolling process for solving the unstable rolling state of coils in a rolling line, comprising the following steps in sequence: slab warehousing, slab heating, high-pressure water descaling, rough rolling, flying shear head and tail trimming, finish rolling, laminar flow cooling, coiling, inspection and warehousing, and coil warehousing; characterized in that: The following steps are performed during the slab heating process: When planning roll changes or maintenance, leave space in the heating furnace so that the unrolled slab is in the third heating section of the heating furnace when rolling stops; The average temperature of the unrolling coil is controlled within the range of 1230±20℃, and the average temperature of the five test passes is controlled within the range of 1060±20℃. Slab temperature difference: By adjusting parameters, the temperature difference between the slab and the slab can be controlled within a range of 30℃; During the finishing rolling process, the following steps are performed: Roll grinding accuracy: Roll unloading, uniform cooling, measuring roll unloading curve, flaw detection, rough grinding, measuring post-grinding curve, fine grinding, measuring post-grinding curve, ensuring roll grinding accuracy, roundness controlled within 0.005mm, taper controlled within 0.005mm; Configure the roll type according to different frames; Corrected deformation resistance coefficient: When there is a deviation between the actual thickness and the calculated thickness of the product, the deformation resistance coefficient is corrected according to the deviation value.

2. The continuous rolling process for solving the unstable rolling state of the coil unwinding process according to claim 1, characterized in that, The parameters include burner injection pressure and air coal.

3. The continuous rolling process for solving the unstable rolling state of the coil unwinding process according to claim 2, characterized in that, The configuration scheme for the roll profile is as follows: 。 4. The continuous rolling process for solving the problem of unstable rolling state during coil unwinding as described in claim 1, characterized in that, The formula for correcting the deformation resistance coefficient based on the deviation value is as follows: S i+1 =S i (1-a)+S r *a ; In the formula, S i S is the deformation resistance coefficient set for the i-th calculation; r The feedback value set for the i-th time; S i+1 is the deformation resistance coefficient used for the (i+1)th setting calculation; a is the self-learning gain factor.

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