Anti-scratch control method for pickling tank body of continuous thermal annealing pickling line

Abstract

The invention discloses an anti-scratch control method for a pickling tank body of a continuous thermal annealing pickling line. The anti-scratch control method comprises pickling section control, inlet section control and annealing furnace control. Specifically, the method starts from the inclination reason of the strip steel in the tank body, the levelness of the steel strip during operation in the pickling tank body is improved, and the phenomenon that the tank body is scratched due to the fact that the heights of the two sides of the strip steel are inconsistent is avoided. Meanwhile, the height and the levelness of the strip steel during operation in the tank body are guaranteed according to the height, the levelness and the perpendicularity of the supporting rollers in the pickling section, and the distance between the steel strip and the tank body is increased by improving the tension of the steel strip during operation in the pickling section. Therefore, the method is a systematic whole-line linkage method, the problem that the steel belt is frequently scratched with the bottom of the pickling section tank body is restrained through systematic means such as equipment body precision, steel belt plate shape control and pickling section tension control, the acid liquor leakage accident caused after the bottom of the tank body is scratched by the strip steel is avoided, and safe, stable and smooth operation of a production line is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgical production, and in particular is a method for controlling the anti-scratching of a pickling tank of a continuous thermal annealing pickling line. Background Art

[0002] The stainless steel hot annealing and pickling line is a production line that anneals and pickles stainless steel into black coils, and is a key unit for cold rolling. It has a fast running speed, high efficiency, and huge workload. Some problems inherent in the production line have not been effectively solved since the birth of the production line. Among them is the problem of frequent scratches on the tank body of the pickling section by the steel strip. The existing treatment method after the tank body is scratched by the strip is that the equipment maintenance personnel remedy the scratches on the tank body by simple repair welding, adding baffles, etc., without studying and curbing this problem from the root.

[0003] Through overall analysis and research on the production line, the applicant found that there are many reasons why the strip scrapes against the trough body. First, the distance between the strip and the bottom of the trough body when it runs in the trough body is too small; second, when the running tension of the steel strip is too small, it is very easy to scrape against the bottom of the trough body; third, the steel strip tilts on one side when it runs in the trough body, which makes it particularly easy to scrape against the bottom of the trough body and cause serious accidents; and the inclination of the steel strip when it runs in the trough body is also affected by various factors, including the sickle bay before and after the weld, the support rollers between the pickling trough bodies, the plate shape of the steel strip itself, and the degree of deviation of the steel strip when entering the pickling section. Summary of the invention

[0004] Based on the above, the purpose of the present invention is to provide a method for preventing the pickling tank of a continuous hot annealing pickling line from being scratched. Starting from the specific reasons causing the strip to scratch the tank, the method controls the accuracy of the pickling equipment, the shape of the running strip, the tension of the steel strip in the pickling section, and the sickle bay before and after the weld between the steel strip and the strip to avoid scratching the bottom of the pickling section tank due to the tilting of the steel strip in the pickling section tank.

[0005] To achieve its purpose, the present invention adopts the following technical solution: The present invention provides a method for controlling the scratch prevention of a pickling tank in a continuous thermal annealing pickling line, which specifically comprises the following steps: Step 1: Pickling section control: (1) Increase the height of the support rollers between the tanks in the pickling section to increase the distance between the steel strip and the tank; (2) Adjust the horizontality and verticality of the support rollers between the tanks in the pickling section to prevent the support rollers from tilting and causing the steel strip to scratch the bottom of the pickling tank; (3) Increase the running tension of the steel belt in the pickling section to increase the distance between the steel belt and the bottom of the tank during operation; (4) Recalibrate the zero position of the correction frame of the correction roller in the pickling section from time to time to avoid the correction roller tilting due to strip detection deviation, which in turn causes the steel strip to tilt and cause the edge of the steel strip to scrape against the pickling tank; Step 2: Entrance section control: (1) Control the steel coil in the middle position of the uncoiler to avoid the edge of the steel coil from falling and scraping the tank body during the pickling section due to the sickle bay in the welds of the two steel coils; (2) Change the manual tail swing of the strip to automatic tail swing to avoid manual tail swing causing the strip to deviate and cause the strip to tilt and scrape the bottom of the pickling tank; (3) Recalibrate the zero position of the correction frame of the 1# and 2# uncoilers to avoid the steel coil being out of the center due to detection deviation, causing the steel strip to tilt and scrape the trough; Step 3: Annealing furnace control: By controlling the cooling section or the spray beam before the cooling section, the occurrence of strip wave defects can be reduced.

[0006] As a further improvement of the technical solution of the present invention, in the pickling section control of step 1, the height of the support rollers between the tanks of the pickling section is uniformly increased to 190 mm.

[0007] Furthermore, in the pickling section control of step 1, the running tension of the steel strip in the pickling section is changed from 1.3-1.5 kg / mm ​​per sheet to 2 Increased to 1.8-2.3 Kg / mm 2 .

[0008] Furthermore, in the control of the annealing furnace in step three, the control method of the spray beam in front of the cooling section is: close 1-2 groups of spray beams in the 70m³ spray beam in front of the cooling section to reduce the single-sided wave defect caused by the steel strip cooling too fast, and avoid the steel strip from scraping against the bottom of the pickling tank due to the large single-sided wave shape.

[0009] Furthermore, in the control of the annealing furnace in step three, the control method of the cooling section spray beam is: regularly clean the cooling section spray beam to avoid uneven cooling in the width direction of the steel strip due to nozzle blockage, resulting in wave-shaped defects and scratches on the bottom of the pickling tank.

[0010] The beneficial effects of the present invention are: 1. The method of the present invention starts from the reason why the strip steel is tilted when the tank body is running, improves the horizontality of the steel strip running in the pickling tank body, and prevents the scraping of the tank body caused by the inconsistent height of the two sides of the strip steel.

[0011] 2. The method of the present invention simultaneously ensures the height and levelness of the strip steel when it runs in the tank body by taking into account the height, levelness and verticality of the support rollers in the pickling section.

[0012] 3. The method of the present invention increases the distance between the steel strip and the tank body by increasing the tension of the steel strip when it runs in the pickling section.

[0013] In summary, the present invention is a systematic full-line linkage method, which is mainly used to control the steel strip before and after the entrance section in the middle position of the production line, avoid the generation of large single-sided waves after the steel strip annealing furnace is cooled, and use high tension when the steel strip is running in the pickling section. At the same time, the height, horizontality and verticality of the support rollers between the pickling section tanks are accurately controlled to ensure that the zero position of the correction roller and the correction frame is the physical zero position. Through the above control method, the problem of frequent scraping of the steel strip against the bottom of the tank body is curbed, and the acid leakage accident after the strip scrapes the bottom of the tank body is avoided, ensuring the safe, stable and smooth operation of the production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the distribution diagram of the strip shape after the verticality of the support rollers between the tanks in the pickling section is different; Figure 2 This is the distribution diagram of the strip shape after the horizontality of the support rollers between the tanks in the pickling section is different; Figure 3 This is a schematic diagram of the scraping between the pickling section strip and the tank body caused by the lowering of the driving side of the strip; Figure 4 This is a schematic diagram of the horizontal running of the strip steel in the tank body after adopting the control method of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below in conjunction with specific embodiments.

[0016] The present invention provides a method for controlling the anti-scratching of a pickling tank in a continuous thermal annealing pickling line, comprising pickling section control, inlet section control and annealing furnace control; 1. Pickling section control method: (1) Raise the height of the support rollers between the tanks in the pickling section to increase the distance between the steel strip and the tank. There are 12 support rollers in the pickling section, and the distance between the bottom of the bearing seat and the bracket varies from 150 to 180 mm, which results in the steel strip having different distances from the bottom of the tank when running between the tanks, which is a serious problem. The present invention uniformly adjusts the distance to 190 mm, which firstly ensures the distance between the steel strip and the bottom of the tank, and secondly ensures that the distance between the steel strip and the bottom of each tank is consistent.

[0017] (2) The strip shape distribution after the verticality of the support rollers between the tanks in the pickling section is different is as follows: Figure 1 As shown in the figure (the red one is slumped on one side, which is easy to scrape against the tank body). The strip shape distribution after the horizontality of the support rollers between the tank bodies in the pickling section is different is as follows Figure 2As shown (DS is the transmission side, OS is the operating side; VDS is the transmission side strip speed, VOS is the operating side strip speed; LDS is the transmission side strip length, LOS is the operating side strip length). The present invention adjusts the horizontality and verticality of the support rollers between the tanks in the pickling section to avoid the scraping of the steel strip caused by the tilt of the support rollers against the bottom of the pickling tank. First, the height of the operating side and the transmission side of the 12 support rollers are precisely adjusted to be consistent, among which the support roller at the 1# tank outlet has a larger height deviation between the operating side and the transmission side, and the deviation is about 5mm; second, the verticality of the 12 support rollers is adjusted to be consistent through a distance meter.

[0018] (3) Increase the running tension of the pickling section steel strip from 1.2-1.4Kg / mm per sheet. 2 Increase to 1.5-1.8Kg / mm 2 , so as to increase the distance between the steel belt and the bottom of the tank when running. The pickling section steel belt running single piece is 1.2kg / mm 2 The typical total tension of each specification is shown in Table 1. The single steel strip running in the pickling section is 1.8kg / mm 2 The typical total tension of each specification at this time is shown in Table 2.

[0019] Table 1 The running weight of the steel strip in the pickling section is 1.2kg / mm 2 Typical total tension of each specification at Table 2 The running weight of the steel strip in the pickling section is 1.8kg / mm 2 Typical total tension of each specification at (4) Recalibrate the zero position of the correction roller and the correction frame in the pickling section to avoid correction caused by strip steel detection deviation The tilt of the roller caused the edge of the steel strip to scrape against the pickling tank. Through measurement, the deviation between the measured value of the internal frame of the correction system of the correction roller in the pickling section and the actual position of the steel strip is about 35mm, which causes the steel strip to always be detected to be biased towards the operating side, causing the correction roller to always correct the steel strip to the transmission side. The correction roller is tilted, causing the transmission side of the steel strip to sag seriously, causing the edge of the transmission side to scrape against the tank more frequently ( Figure 3 ).

[0020] 2. Entrance section control method: (1) Mark the mandrels of the uncoilers of Line 1 and Line 2 and place the steel coil in the middle; there are three widths of marks: 1030mm, 1250mm, and 1530mm.

[0021] (2) The manual tail swing of the strip is changed to automatic tail swing through the annealing pickling line's built-in program to avoid the strip deviation caused by manual tail swing, which causes the strip to tilt inside the pickling tank and scrape the bottom of the tank. The manual tail swing speed is 15m / min. During manual tail swing, the strip has no tension, which will cause the strip to deviate. During automatic tail swing, the speed of the entrance roller is 14m / min. The slow speed of the roller can create micro-tension, which can slow down the strip deviation during tail brushing.

[0022] (3) Recalibrate the zero position of the correction frame of the 1# uncoiler and the 2# uncoiler to avoid the scraping of the trough caused by the steel strip tilting due to the steel coil not being in the center position due to the detection deviation. Through calibration, the zero position of the correction frame of the 1# uncoiler has no deviation, while the zero position of the correction frame of the 2# uncoiler deviates from the actual physical zero position by 25mm, so recalibrate it.

[0023] 3. Annealing furnace control method: (1) Close 1-2 groups of the 70m³ spray beams in front of the cooling section to reduce the unilateral wave defects caused by the rapid cooling of the steel strip and prevent the steel strip from scraping against the bottom of the pickling tank due to the large unilateral wave shape.

[0024] (2) Clean the spray beam of the cooling section every month.

[0025] Application Examples 1. During the downtime period, measure the position of the steel strip in the tank, and recalibrate the height, verticality, and horizontality of the 12 rollers (Table 3); at the same time, correct the zero position of the correction frame of the pickling section correction roller. After calibration, start the machine for testing, and the strip runs horizontally in the tank. Figure 4 shown.

[0026] Table 3 Measurement results of actual position of steel strip in pickling section 2. Start production and control the tension in the pickling section according to the tension mode in Table 4 below. The steel strip in the pickling section runs stably.

[0027] Table 4 Actual tension of steel strip in pickling section By adopting the above control method, the tank body was not scratched again during the two-year operation of the production line, which proves that the control method of the present invention is effective.

Claims

1. A method for preventing scratches on a pickling tank in a continuous thermal annealing pickling line, characterized in that: The following steps are involved: Step 1: Pickling section control: (1) Increase the height of the support rollers between the tanks in the pickling section to increase the distance between the steel strip and the tank; (2) Adjust the horizontality and verticality of the support rollers between the tanks in the pickling section to prevent the support rollers from tilting and causing the steel strip to scratch the bottom of the pickling tank; (3) Increase the running tension of the steel belt in the pickling section to increase the distance between the steel belt and the bottom of the tank during operation; (4) Recalibrate the zero position of the correction frame of the correction roller in the pickling section from time to time to avoid the correction roller tilting due to strip detection deviation, which in turn causes the steel strip to tilt and cause the edge of the steel strip to scrape against the pickling tank; Step 2: Entrance section control: (1) Control the steel coil in the middle position of the uncoiler to avoid the edge of the steel coil from falling and scraping the tank body during the pickling section due to the sickle bay in the welds of the two steel coils; (2) Change the manual tail swing of the strip to automatic tail swing to avoid manual tail swing causing the strip to deviate and cause the strip to tilt and scrape the bottom of the pickling tank; (3) Recalibrate the zero position of the correction frame of the 1# and 2# uncoilers to avoid the steel coil being out of the center due to detection deviation, causing the steel strip to tilt and scrape the trough; Step 3: Annealing furnace control: By controlling the cooling section or the spray beam before the cooling section, the occurrence of strip wave defects can be reduced.

2. A method for controlling the scratch resistance of a pickling tank in a continuous thermal annealing pickling line according to claim 1, characterized in that: In the pickling section control of step 1, the height of the support rollers between the tanks in the pickling section is uniformly increased to 190 mm.

3. A method for controlling the scratch resistance of a pickling tank in a continuous thermal annealing pickling line according to claim 2, characterized in that: In the pickling section control of step 1, the running tension of the pickling section steel strip is increased from 1.3-1.5Kg / mm per sheet to 2 Increased to 1.8-2.3Kg / mm 2 .

4. A method for controlling the scratch prevention of a pickling tank in a continuous thermal annealing pickling line according to claim 3, characterized in that: In the step 3 annealing furnace control, the control method of the spray beam in front of the cooling section is: close the 70m in front of the cooling section 3 1-2 groups of spray beams in the spray beam can reduce the single-sided wave defect caused by the rapid cooling of the steel strip, and avoid the steel strip from scraping against the bottom of the pickling tank due to the large single-sided wave.

5. A method for controlling the scratch resistance of a pickling tank in a continuous thermal annealing pickling line according to claim 4, characterized in that: In the control of the annealing furnace in step three, the control method of the cooling section spray beam is: regularly clean the cooling section spray beam to avoid uneven cooling in the width direction of the steel strip due to nozzle blockage, resulting in wave-shaped defects and scratches on the bottom of the pickling tank.

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