A method for improving the production efficiency of thin-gauge pickled steel in a short process

Abstract

The present invention discloses a method for improving the production efficiency of thin-gauge pickled steel in a short process. The controlled rolling and cooling technology includes four improvements: optimizing the head and tail roll gap compensation parameters, optimizing the mill load distribution and roll cooling parameters, developing a feedforward compensation layer cooling technology based on strip speed prediction, and improving the coiling pinch rolls. The present invention ensures the stability of the thin-gauge strip rolling process by developing head and tail roll gap compensation technology. Combined with optimizing mill load distribution and roll cooling parameters, the method effectively addresses the issue of roll surface quality degradation in F2-4 stands. Furthermore, the method develops a feedforward compensation layer cooling technology based on strip speed prediction to improve product performance stability. Anti-sticking pinch rolls are used in coiling to address the problem of scrap steel sticking to the pinch rolls. This method enables efficient production of thin-gauge pickled steel in a short process, significantly reducing process costs.

Description

Technical Field

[0001] The invention belongs to the technical field of steel product manufacturing, and particularly relates to a method for improving the production efficiency of short-process thin-gauge pickled steel. Background Art

[0002] As the steel industry strives for green manufacturing, the thin slab continuous casting and rolling process (short process) for producing thin-gauge hot-rolled strip has seen significant development. This process offers a wide range of products, including low-carbon steel, medium- and high-carbon steel, automotive steel, pickled steel, galvanized steel, and color-coated steel. It is widely used in industries such as automotive parts manufacturing, power engineering, machinery manufacturing, and hardware tools. The mechanical and application properties of thin-gauge pickled steel produced on short-process lines are comparable to those of cold-rolled products of the same thickness, enabling the use of heat instead of cold. However, this process lags behind traditional hot-rolled and cold-rolled products in terms of production efficiency, resulting in high process costs and significantly hindering its widespread adoption.

[0003] The problems existing in the production of thin-gauge pickled steel on existing short-process production lines are mainly manifested in:

[0004] (1) The low silicon content design of the short-process pickled steel and the high surface quality requirements lead to a narrow process control window. It is necessary to reduce the drawing speed to 4.2m / min and the billet thickness to 60mm to maintain the feed rate, resulting in low production efficiency and high process costs.

[0005] (2) The thinnest short-process pickled billet is 60 mm, while the traditional hot rolling is 38 mm. The rolling load of the stand is large, and the finishing rolling inlet temperature is high. Under the dual effects of large shear stress and rapid increase in roll temperature, the roll surface quality deteriorates, and frequent roll changes restrict the improvement of production efficiency.

[0006] (3) The rolling stability of thin-gauge pickled steel is poor, the head of the strip is thin, and it is easy to be inserted into the gap between the finishing rolling and coiling equipment, resulting in scrap steel, and the tail is frequently thrown off, which seriously affects the improvement of production efficiency;

[0007] (4) During the high-speed rolling of thin-gauge pickled steel, the laminar feedback control lag and water valve delay lead to low control accuracy of intermediate temperature and coiling temperature, affecting the stability of product performance. The rolling speed has to be limited, resulting in low production efficiency.

[0008] The above problems belong to short-process manufacturing, pain points and difficult problems in the industry, and they need to be solved urgently to achieve efficient production of short-process thin-gauge pickled steel and reduce process costs. Summary of the Invention

[0009] The present invention aims to overcome the shortcomings of the existing technology and provide a method for improving the production efficiency of thin-gauge pickled steel in a short process; by developing the rolling mill head and tail roll gap compensation technology to ensure the stability of the thin-gauge strip rolling process, and combining the optimization of the rolling mill load distribution and the roll cooling parameters and other means, the problem of F2~4 stand roll surface quality deterioration is effectively solved, and at the same time, the feedforward compensation layer cooling technology based on strip speed prediction is developed to improve product performance stability, and the coiling adopts anti-sticking pinch rollers to solve the problem of scrap steel sticking to the pinch rollers, which can realize the efficient production of thin-gauge pickled steel in a short process and significantly reduce the process cost.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] A method for improving the production efficiency of thin-gauge pickled steel in a short process, including controlled rolling and controlled cooling technology, is improved mainly in four aspects: optimizing the compensation parameters of the head and tail roll gaps of the rolling mill, optimizing the rolling mill load distribution and roll cooling parameters, developing a feedforward compensation layer cooling technology based on strip speed prediction, and using anti-sticking pinch rolls for coiling. The main control requirements are as follows:

[0012] (1) Roll gap compensation at the head of the rolling mill: The head of thin-gauge strip is too thin, which is easy to be inserted into the gap between the finishing rolling and coiling equipment, resulting in scrap steel. A certain amount of thickness compensation is embedded in the roll gap at the head of the rolling mill to achieve the effect of thickening the strip head, and the thickening part of the strip head cannot affect the secondary self-learning and the normal setting of the next piece of steel. When the rolling thickness (the thickness of the produced steel coil, i.e. the target thickness; the same below) is ≤3.0mm (when it is greater than 3.0mm, no compensation means are required), the automatic compensation technology of the roll gap at the head of the rolling mill is put into use. The specific control means and conditions include:

[0013] ① For F4-7 stands, the thickness of the rolling mill head is embedded 0.3-1.0mm;

[0014] ② For F1 to 7 stands, the automatic thickness control function of the strip head is not used;

[0015] ③ After the load of F1~7 stands is established, the thickness embedded value is reset to zero within the control sequence of 0.2~0.6s, and the rolling mill roll gap adjustment rate is controlled to 1.0~2.0mm / s. At the same time, the thickness automatic control function is automatically put into use to ensure that the finished product thickness meets the standard;

[0016] (2) Compensation for the roll gap at the tail end of the rolling mill:

[0017] When the rolling thickness is ≤3.0mm, the automatic compensation technology for the roll gap at the tail of the rolling mill is used. The specific control means and conditions include:

[0018] ① For F1-3 stands, when the distance between the tail of the strip and the center line of the mill is 0.8-1.5m, and the actual thickness detected is 0.08-0.12mm lower than the threshold value of the reference thickness, the roll gap compensation is immediately started;

[0019] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail of the rolling mill is 0.05~0.2mm;

[0020] (3) Optimize mill load distribution and roll cooling parameters

[0021] Mill load distribution type: ①F1-2 stands adopt reduction rate distribution, ②F3-7 stands adopt rolling force distribution; at the same time, ensure that the unit rolling force of F1-7 is: F1≤2.6t / mm, F2≤1.9t / mm, F3≤1.7t / mm, F4≤1.5t / mm, F5≤1.4t / mm, F6≤1.3t / mm, F7≤1.2t / mm;

[0022] Roll cooling parameters: ① Total cooling water volume of finishing rolling work roll 5100~5600m 3 / h, and the cooling water volume for the upper work rolls accounts for 42-45% of the total water volume, while the cooling water volume for the lower work rolls accounts for 55-58% of the total water volume. This is because the cooling water of the upper work rolls stays for a long time at the upper cut-off plate, resulting in a temperature difference between the upper and lower work rolls. ② The cooling water volume of the work rolls of the F2-4 stands accounts for 52-58% of the total water volume. ③ The temperature of the F2-4 work rolls at the bottom of the machine is ≤68°C, the temperature difference along the longitudinal direction of the F2-4 work rolls is ≤15°C, and the average temperature difference between the upper and lower work roll surfaces of the F2-4 work rolls is ≤3°C.

[0023] (4) Use of layer cooling feedforward compensation technology based on strip speed prediction

[0024] Laminar cooling consists of a coarse adjustment section (laminar front coarse adjustment section), an air cooling section (middle air cooling section) and a fine adjustment section (rear fine adjustment section). The water volume per unit length in the coarse adjustment section is controlled at 110-130m 3 / h·m, the water volume per unit length of the downward spray is controlled at 170~190m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 80~100m 3 / h·m, the water volume per unit length of the downward spray is controlled at 140~160m 3 / h·m; the maximum rolling speed is controlled to not exceed 17m / s, and the opening and closing response time of the layer cooling water valve is ≤0.8 seconds. Based on the above control requirements, conventional means are used to use the time-speed diagram to predict the future speed of the strip in real time and transmit it to the layer cooling secondary model. The laminar flow header configuration and cooling compensation water volume are calculated in advance. This solves the problems of laminar flow feedback control lag and water valve delay during the speed increase of thin-gauge pickled steel. The control accuracy of intermediate temperature and coiling temperature exceeds 96%, and the product performance is stable.

[0025] (5) The coiling adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC54~56; the hardness uniformity is high to prevent the scrap steel from sticking due to the local soft hardness of the pinch roller under high load conditions.

[0026] The main chemical composition of the anti-adhesion pinch roller, calculated by mass percentage, meets the following requirements: C 0.2-0.4%, Si 0.6-0.8%, Mn 1.8-2.2%, Cr 6.5-7.5%, Mo 1.2-1.7%, V 0.3-0.7%, W 1.0-1.4%, P≤0.016%, S≤0.005%, Als 0.01-0.05%, N≤0.005%, with the remainder being Fe and unavoidable impurities. By increasing the Mn content and reducing the Cr content, the wear mechanism is mainly oxidative wear. When the pinch roller and the strip are grinding against each other, oxides are easily formed to play a lubricating role, avoiding direct contact and welding, and further reducing the risk of scrap steel adhesion.

[0027] In the above scheme, the mill head roll gap compensation step described in step (1) is adopted, and the actual thickness of the strip head tip is increased by 0.08 to 0.10 mm, which can effectively avoid the problem of thin-gauge strip heads being inserted into the gaps between finishing rolling and coiling related equipment to generate scrap steel.

[0028] In the above scheme, a hydraulic valve group is added to the F1~3 frames, so that the roll gap can be quickly lifted at the tail of the strip to improve the deformation of the strip tail; when the tail of the strip is about to leave a certain frame, the roll gap is detected and quickly lifted, so that the tongue-shaped length of the strip tail is shortened, which can effectively alleviate the risk of tail swinging when throwing thin-gauge strips, and reduce the cutting loss of the strip tail.

[0029] In the above scheme, the mill tail roll gap compensation step shown in step (2) is adopted, and the actual measured strip tail tongue length is shortened by 25-35%, effectively reducing the risk of thin-gauge strip throwing and tail swinging.

[0030] In the above scheme, in the reduction rate distribution step of the F1-2 frames, the F1 reduction rate is 60-65%, and the F2 reduction rate is 45-50%; at the same time, the F1 bite angle is ≤17.5°, and the F2 bite angle is ≤15°, which has the effect of preventing scrap steel from slipping.

[0031] In the above solution, the rolling force distribution of the F3 to F7 stands is set in a descending order.

[0032] In the above scheme, the step (3) of optimizing the mill load distribution and the roll cooling parameters can solve the problem of deterioration of the working roll surface quality of the F2-4 stands due to the large shear stress and the rapid increase in roll temperature. The pickling steel roll replacement cycle is increased from the traditional 600 tons to more than 1100 tons.

[0033] In the above solution, the thin gauge refers to hot-rolled strip steel with a rolling thickness of ≤3.0 mm.

[0034] In the above scheme, the chemical composition of the pickled steel, calculated by mass percentage, includes: C 0.03-0.07%, Si 0.11-0.3%, Mn 0.30-1.3%, P≤0.015%, S≤0.006%, Cr 0.30-0.55%, Ti 0.035-0.11%, Nb 0.02-0.05%, Als 0.02-0.06%, N≤0.006%, and the balance is Fe and unavoidable impurities.

[0035] The above technical solution can significantly improve the production efficiency of short-process thin-gauge pickled steel, increase the slab pulling speed from 4.2m / min to 5.5m / min, and increase the slab thickness from 60mm to 75mm; the production efficiency is increased by more than 10%, the process cost is reduced by more than 20 yuan / ton, and the spot rate of the entire process is reduced to less than 5%.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention adopts the roll gap compensation at the head of the rolling mill, and the actual thickness of the tip of the strip head is increased by 0.08 to 0.10 mm, which effectively avoids the problem of scrap steel caused by the head of thin-gauge strip being inserted into the gap between the finishing rolling and coiling related equipment; combined with the roll gap compensation means at the tail of the rolling mill, the actual length of the tongue of the strip tail is shortened by 25 to 35%, effectively reducing the risk of thin-gauge strip being thrown off the tail.

[0038] 2. By optimizing the mill load distribution and roll cooling process, the present invention can effectively solve the problem of work roll surface quality deterioration caused by large shear stress and rapid increase in roll temperature in F2-4 stands. The roll replacement cycle for pickled steel can be increased from the traditional 600 tons to over 1,100 tons, and the work roll surface quality rating is A.

[0039] 3. The present invention regulates parameters such as the water spray volume and maximum rolling speed in different links of laminar cooling, and combines conventional time-speed diagrams to predict the future speed of the strip in real time and transmit it to the laminar cooling secondary model, calculates the laminar manifold configuration and cooling compensation water volume in advance, and solves the problems of laminar feedback control lag and water valve delay in the high-speed rolling process of thin-gauge pickled steel. The control accuracy of intermediate temperature and coiling temperature exceeds 96%, the product performance is stable, and the maximum rolling speed of short-process thin-gauge pickled steel reaches 17m / s.

[0040] 4. This invention ensures the stability of the thin-gauge strip rolling process by developing head and tail roll gap compensation technology. It also addresses the issue of roll surface quality degradation on F2-4 stands through optimized mill load distribution and roll cooling parameters. Feedforward compensation layer cooling technology based on strip speed prediction improves product performance stability. Anti-sticking pinch rolls are used in the coiling process to address the problem of scrap steel sticking to the pinch rolls. This effectively improves the production efficiency of thin-gauge pickled steel in a short process. The slab drawing speed can be increased from the traditional 4.2 m / min to 5.5 m / min, and the slab thickness can be increased from 60 mm to 75 mm. This improves production efficiency by over 10%, reduces process costs by over 20 yuan / ton, and reduces the overall spot rate to below 5%, making it suitable for widespread application. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below through a specific implementation case. This implementation case is specifically implemented based on the technology of the present invention, and a detailed implementation method and specific operation process are now given, but the scope of protection of the present invention is not limited to the implementation case given below.

[0042] In the following embodiments, the short process production line includes the steps of molten steel smelting → thin slab continuous casting → slab descaling in front of the furnace → slab heating → descaling before finishing rolling → 7-stand finishing rolling → laminar cooling → coiling. The main improvement lies in the controlled rolling and cooling process of 7-stand finishing rolling, laminar cooling and coiling.

[0043] In the following embodiments, an anti-adhesion pinch roller is used in the winding step. The main chemical components of the anti-adhesion pinch roller, calculated by mass percentage, meet the following requirements: C 0.35%, Si 0.7%, Mn 2.1%, Cr 6.5%, Mo 1.5%, V 0.6%, W 1.2%, P 0.012%, S 0.005%, Als 0.03%, N 0.004%, and the balance is Fe and unavoidable impurities.

[0044] Example 1

[0045] A short-process production line is used to produce pickled steel SPHC-MJ with a specification of 1.2 mm*1250 mm. The chemical composition, by mass percentage, includes: C 0.045%, Si 0.16%, Mn 0.7%, P 0.011%, S 0.005%, Cr 0.45%, Ti 0.065%, Nb 0.035%, Al 0.04%, N 0.004%, and the balance is Fe and unavoidable impurities.

[0046] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0047] (1) Roll gap compensation at the head of the rolling mill; when the rolling thickness is ≤3.0mm, the automatic compensation function of the roll gap at the head of the rolling mill is used; the specific control means and conditions include:

[0048] ①F4~7 frames, the head thickness is embedded 0.6mm;

[0049] ② For F1 to 7 stands, the automatic thickness control function of the strip head is not used;

[0050] ③ After the load of F1~7 stands is established, the thickness embedded value is reset to zero within the control sequence of 0.4s, the rolling mill roll gap adjustment rate is controlled to 2.0mm / s, and the thickness automatic control function is automatically put into use;

[0051] (2) Compensation for the tail roll gap of the rolling mill; when the rolling thickness is ≤3.0mm, the compensation function for the tail roll gap of the rolling mill is used; the specific control means and conditions include:

[0052] ① For the F1-3 stand, the distances between the tail of the strip and the centerline of the mill are 1.5m, 1.2m, and 1.0m, respectively. When the actual thickness is detected to be 0.12mm, 0.10mm, and 0.08mm lower than the reference thickness, roll gap compensation is immediately initiated.

[0053] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.10mm;

[0054] (3) mill load distribution and roll cooling parameters;

[0055] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, where F1 reduction ratio is 60% and F2 reduction ratio is 50%, and the bite angle of F1 is 16.9° and F2 bite angle is 14°; ② F3-7 stands adopt rolling force distribution, and the rolling force is set from large to small; among them, the unit rolling force of F1-7 specifically meets the following requirements: F1 is 2.4t / mm, F2 is 1.8t / mm, F3 is 1.65t / mm, F4 is 1.42t / mm, F5 is 1.3t / mm, F6 is 1.21t / mm, and F7 is 1.06t / mm;

[0056] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5100m 3 / h, and the cooling water volume of the upper working roll is 45% of the total water volume, and the cooling water volume of the lower working roll is 55% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 58% of the total water volume, the working roll temperature at the bottom of the machine is 67℃, the temperature difference along the length of the roll body is 15℃, and the average temperature difference of the roll surface is 2℃;

[0057] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling coarse adjustment section is controlled at 110m 3 / h·m, the water volume per unit length of the downward spray is controlled at 190m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 100m3 / h·m, the water volume per unit length of the downward spray is controlled at 140m 3 / h·m; the maximum rolling speed for pickled steel is 16.5m / s, and the response time for opening and closing the laminar cooling water valve is 0.8s. Based on the above control requirements, conventional methods are used to use time-speed diagrams to predict the future speed of the strip in real time and transfer them to the laminar cooling secondary model to calculate the laminar flow header configuration and cooling compensation water volume in advance. The control accuracy of the laminar intermediate temperature and coiling temperature is 96.5% and 96%, respectively.

[0058] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC54~55;

[0059] Pickled steel production is stable, with a roll change cycle of 1,080 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, with a slab thickness of 75 mm. Pickled steel production efficiency has increased by 12%, process costs have been reduced by 23 yuan / ton, and the full-process spot rate is 3.6%.

[0060] Example 2

[0061] A short-process production line is used to produce pickled steel SPHC-MJ with a specification of 2.0mm*1250mm. The chemical composition, by mass percentage, includes: C 0.05%, Si 0.18%, Mn 0.9%, P 0.012%, S 0.005%, Cr 0.55%, Ti 0.085%, Nb 0.02%, Als 0.06%, N 0.006%, and the balance is Fe and unavoidable impurities.

[0062] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0063] (1) Roll gap compensation at the head of the rolling mill; when the rolling thickness is ≤3.0mm, the automatic compensation function of the roll gap at the head of the rolling mill is used; the specific control means and conditions include:

[0064] ①F4~7 frames, the head thickness is embedded 0.3mm;

[0065] ② For F1 to 7 stands, the automatic thickness control function of the strip head is not used;

[0066] ③ After the load of F1~7 stands is established, the thickness embedded value is reset to zero within 0.2 seconds of the control sequence, the rolling mill roll gap adjustment rate is controlled to 1.0mm / s, and the thickness automatic control function is automatically put into use;

[0067] (2) Compensation for the tail roll gap of the rolling mill; when the rolling thickness is ≤3.0mm, the compensation function for the tail roll gap of the rolling mill is used; the specific control means and conditions include:

[0068] ① For the F1-3 stand, the distances between the tail of the strip and the centerline of the rolling mill are 1.2m, 1.0m, and 0.8m, respectively. When the actual thickness is detected to be lower than the reference thickness by 0.12mm, 0.10mm, and 0.10mm, respectively, roll gap compensation is immediately initiated.

[0069] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.20mm;

[0070] (3) Mill load distribution and roll cooling parameters

[0071] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, where F1's reduction ratio is 61% and F2's reduction ratio is 45%, and the bite angles of F1 and F2 are 16.2° and 14.3°, respectively. ② F3-7 stands adopt rolling force distribution, with the rolling force set from large to small. Specifically, the unit rolling forces of F1-7 meet the following requirements: F1 is 2.5t / mm, F2 is 1.7t / mm, F3 is 1.6t / mm, F4 is 1.38t / mm, F5 is 1.25t / mm, F6 is 1.16t / mm, and F7 is 1.1t / mm.

[0072] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5600m 3 / h, and the cooling water volume of the upper working roll is 42% of the total water volume, and the cooling water volume of the lower working roll is 58% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 58% of the total water volume, the working roll temperature at the bottom of the machine is 60℃, the temperature difference along the length of the roll body is 10℃, and the average temperature difference of the roll surface is 3℃;

[0073] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling rough adjustment section is controlled at 130m 3 / h·m, the water volume per unit length of the downward spray is controlled at 170m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 80m 3 / h·m, the water volume per unit length of the downward spray is controlled at 160m 3 / h·m; the maximum rolling speed for pickled steel is 14m / s, and the response time for opening and closing the laminar cooling water valve is 0.7s. Based on the above control requirements, conventional methods are used to use time-speed diagrams to predict the future strip speed in real time and transfer them to the laminar cooling secondary model to calculate the laminar flow header configuration and cooling compensation water volume in advance. The control accuracy of the laminar intermediate temperature and coiling temperature are 96.7% and 96.6%, respectively.

[0074] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets: HRC55~56;

[0075] Pickled steel production is stable, with a roll change cycle of 1,200 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, with a slab thickness of 75 mm. Pickled steel production efficiency has increased by 15%, process costs have been reduced by 35 yuan / ton, and the overall spot rate is 1.7%.

[0076] Example 3

[0077] A short-process production line is used to produce pickled steel HTC2 with a specification of 1.67mm*1500mm. The chemical composition, by mass percentage, includes: C 0.055%, Si 0.3%, Mn 1.3%, P 0.015%, S 0.006%, Cr 0.55%, Ti 0.035%, Nb 0.02%, Als 0.06%, N 0.006%, and the balance is Fe and unavoidable impurities.

[0078] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0079] (1) Roll gap compensation at the head of the rolling mill; when the rolling thickness is ≤3.0mm, the automatic compensation function of the roll gap at the head of the rolling mill is used; the specific control means and conditions include:

[0080] ①F4-7 frame, the head thickness is embedded 0.8mm;

[0081] ② For the F1-7 frame, the automatic thickness control function is not used at the strip head;

[0082] ③ After the F1-7 stand load is established, the thickness pre-embedded value is reset to zero within the control sequence of 0.4s, the rolling mill roll gap adjustment rate is controlled to 1.2mm / s, and the thickness automatic control function is automatically put into use;

[0083] (2) When the rolling thickness of the tail roll gap compensation of the rolling mill is ≤3.0mm, the tail roll gap compensation function of the rolling mill is put into use; the specific control means and conditions include:

[0084] ① For the F1-3 stand, the distances between the tail of the strip and the centerline of the rolling mill are 1.5m, 1.2m, and 1.0m, respectively. When the actual thickness is detected to be lower than the reference thickness by 0.08mm, 0.12mm, and 0.12mm, respectively, roll gap compensation is immediately initiated.

[0085] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.11mm;

[0086] (3) mill load distribution and roll cooling parameters;

[0087] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, with F1's reduction ratio being 62% and F2's reduction ratio being 47%, and meeting the requirements of F1's bite angle of 16.5° and F2's bite angle of 14.5°; ② F3-7 stands adopt rolling force distribution, with the rolling force set in descending order; the unit rolling forces of F1-7 meet the following requirements: F1 is 2.6t / mm, F2 is 1.76t / mm, F3 is 1.63t / mm, F4 is 1.4t / mm, F5 is 1.22t / mm, F6 is 1.12t / mm, and F7 is 1.03t / mm;

[0088] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5200m 3 / h, and the cooling water volume of the upper working roll is 43% of the total water volume, and the cooling water volume of the lower working roll is 57% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 56% of the total water volume, the working roll temperature at the bottom of the machine is 61℃, the temperature difference along the length of the roll body is 12℃, and the average temperature difference of the roll surface is 2℃;

[0089] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling coarse adjustment section is controlled at 125m 3 / h·m, the water volume per unit length of the downward spray is controlled at 175m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 90m 3 / h·m, the water volume per unit length of the downward spray is controlled at 150m 3 / h·m; the maximum rolling speed of pickled steel is 16.2m / s, and the response time for opening and closing the laminar cooling water valve is 0.6s. Based on the above-mentioned control requirements, conventional means are used to use the time-speed diagram to predict the future speed of the strip in real time and transfer it to the laminar cooling secondary model. The laminar flow header configuration and cooling compensation water volume are calculated in advance. The control accuracy of the laminar intermediate temperature and coiling temperature are 96.5% and 96.2%, respectively.

[0090] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC54~56.

[0091] Pickled steel production is stable, with a roll change cycle of 1,100 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, with a slab thickness of 75 mm. Pickled steel production efficiency has increased by 12%, process costs have been reduced by 26 yuan / ton, and the full-process spot rate is 3.8%.

[0092] Example 4

[0093] A short-process production line is used to produce pickled steel SPHC with a specification of 1.1mm*1250mm. The chemical composition, by mass percentage, includes: C 0.03%, Si 0.11%, Mn 0.30%, P 0.014%, S 0.004%, Cr 0.30%, Ti 0.11%, Nb 0.05%, Als 0.02%, N 0.004%, and the balance is Fe and unavoidable impurities.

[0094] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0095] (1) Roll gap compensation at the head of the rolling mill; when the rolling thickness is ≤3.0mm, the automatic compensation function of the roll gap at the head of the rolling mill is used; the specific control means and conditions include:

[0096] ①F4-7 frame, head thickness embedded 1.0mm;

[0097] ② For the F1-7 frame, the automatic thickness control function is not used at the strip head;

[0098] ③ After the F1-7 stand load is established, the thickness pre-embedded value is reset to zero within the control sequence of 0.6 seconds, the rolling mill roll gap adjustment rate is controlled to 1.0mm / s, and the thickness automatic control function is automatically put into use;

[0099] (2) When the rolling thickness of the tail roll gap compensation of the rolling mill is ≤3.0mm, the tail roll gap compensation function of the rolling mill is put into use; the specific control means and conditions include:

[0100] ① For the F1-3 stand, the distances between the tail of the strip and the centerline of the mill are 1.5m, 1.5m, and 1.0m, respectively. When the actual thickness is detected to be lower than the reference thickness by 0.08mm, 0.08mm, and 0.12mm, respectively, roll gap compensation is immediately initiated.

[0101] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.10mm;

[0102] (3) mill load distribution and roll cooling parameters;

[0103] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, with F1's reduction ratio being 65% and F2's reduction ratio being 50%, and meeting the requirements of F1's bite angle of 17.5° and F2's bite angle of 15°; ② F3-7 stands adopt rolling force distribution, with the rolling force set in descending order; the unit rolling forces of F1-7 meet the following requirements: F1 is 2.3t / mm, F2 is 1.9t / mm, F3 is 1.7t / mm, F4 is 1.5t / mm, F5 is 1.32t / mm, F6 is 1.2t / mm, and F7 is 1.0t / mm;

[0104] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5300m 3 / h, and the cooling water volume of the upper working roll is 45% of the total water volume, and the cooling water volume of the lower working roll is 55% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 54% of the total water volume, the working roll temperature at the bottom of the machine is 68℃, the temperature difference along the length of the roll body is 13℃, and the average temperature difference of the roll surface is 3℃;

[0105] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling coarse adjustment section is controlled at 115m 3 / h·m, the water volume per unit length of the downward spray is controlled at 185m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 95m 3 / h·m, the water volume per unit length of the downward spray is controlled at 145m 3 / h·m; the maximum rolling speed of pickled steel is 17m / s, and the opening and closing response time of the laminar cooling water valve is 0.8s. Based on the above control requirements, conventional means are used to use the time-speed diagram to predict the future speed of the strip in real time and transfer it to the laminar cooling secondary model. The laminar flow header configuration and cooling compensation water volume are calculated in advance. The control accuracy of the laminar intermediate temperature and coiling temperature are 96.2% and 96.5%, respectively.

[0106] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC55~56.

[0107] Pickled steel production is stable, with a roll change cycle of 1,050 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, with a slab thickness of 75 mm. Pickled steel production efficiency has increased by 11%, process costs have been reduced by 21 yuan / ton, and the full-process spot rate is 4.9%.

[0108] Example 5

[0109] A short-process production line is used to produce pickled steel QStE550TM with a specification of 1.5mm*1250mm. The chemical composition, by mass percentage, includes: C 0.07%, Si 0.3%, Mn 0.30%, P 0.015%, S 0.005%, Cr 0.55%, Ti 0.055%, Nb 0.02%, Als 0.03%, N 0.005%, and the balance is Fe and unavoidable impurities.

[0110] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0111] (1) Roll gap compensation at the head of the rolling mill; when the rolling thickness is ≤3.0mm, the automatic compensation function of the roll gap at the head of the rolling mill is used; the specific control means and conditions include:

[0112] ①F4-7 frame, the head thickness is embedded 0.5mm;

[0113] ② For the F1-7 frame, the automatic thickness control function is not used at the strip head;

[0114] ③ After the F1-7 stand load is established, the thickness embedded value is reset to zero within 0.2 seconds of the control sequence, the rolling mill roll gap adjustment rate is controlled to 2.0mm / s, and the thickness automatic control function is automatically put into use;

[0115] (2) Roll gap compensation at the tail end of the rolling mill

[0116] ① Put the roll gap compensation function at the tail end of the rolling mill into use;

[0117] ② For the F1-3 stand, the distances between the strip tail and the centerline of the rolling mill are 1.2m, 1.2m, and 0.8m, respectively. When the actual thickness is detected to be 0.10mm, 0.12mm, and 0.10mm lower than the reference thickness, roll gap compensation is immediately initiated.

[0118] ③ For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.12mm;

[0119] (3) mill load distribution and roll cooling parameters;

[0120] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, with F1's reduction ratio being 60% and F2's reduction ratio being 47%, and meeting the requirements of F1's bite angle of 16.2° and F2's bite angle of 13.9°; ② F3-7 stands adopt rolling force distribution, with the rolling force set from large to small; the unit rolling forces of F1-7 meet the following requirements: F1 is 2.35t / mm, F2 is 1.81t / mm, F3 is 1.58t / mm, F4 is 1.35t / mm, F5 is 1.3t / mm, F6 is 1.1t / mm, and F7 is 1.02t / mm;

[0121] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5500m 3 / h, and the cooling water volume of the upper working roll is 44% of the total water volume, and the cooling water volume of the lower working roll is 56% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 53% of the total water volume, the working roll temperature at the bottom of the machine is 57℃, the temperature difference along the length of the roll body is 15℃, and the average temperature difference of the roll surface is 1℃;

[0122] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling coarse adjustment section is controlled at 120m 3 / h·m, the water volume per unit length of the downward spray is controlled at 180m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 100m 3 / h·m, the water volume per unit length of the downward spray is controlled at 140m 3 / h·m; the maximum rolling speed of pickled steel is 14.5m / s, and the opening and closing response time of the laminar cooling water valve is 0.6s. Based on the above-mentioned control requirements, conventional means are used to use the time-speed diagram to predict the future speed of the strip in real time and transfer it to the laminar cooling secondary model. The laminar flow header configuration and cooling compensation water volume are calculated in advance. The control accuracy of the laminar intermediate temperature and coiling temperature are 97.2% and 97.8%, respectively.

[0123] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC55~56.

[0124] Pickled steel production is stable, with a roll change cycle of 980 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, and slab thickness is 75 mm. Pickled steel production efficiency has increased by 13%, process costs have been reduced by 25 yuan / ton, and the full-process spot rate is 2.8%.

[0125] Example 6

[0126] A short-process production line is used to produce pickled steel SAPH440 with a specification of 3.0mm*1000mm. The chemical composition, by mass percentage, includes: C 0.04%, Si 0.12%, Mn 0.6%, P 0.011%, S 0.005%, Cr 0.35%, Ti 0.09%, Nb 0.03%, Als 0.05%, N 0.005%, and the balance is Fe and unavoidable impurities.

[0127] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0128] (1) When the rolling thickness of the mill head roll gap compensation is ≤3.0mm, the automatic compensation function of the mill head roll gap is used; the specific control means and conditions include:

[0129] ①F4-7 frame, the head thickness is embedded 0.3mm;

[0130] ② For the F1-7 frame, the automatic thickness control function is not used at the strip head;

[0131] ③ After the F1-7 stand load is established, the thickness pre-embedded value is reset to zero within 0.3 seconds of the control sequence, the rolling mill roll gap adjustment rate is controlled to 1.5mm / s, and the thickness automatic control function is automatically put into use;

[0132] (2) Compensation for the tail roll gap of the rolling mill; when the rolling thickness is ≤3.0mm, the compensation function for the tail roll gap of the rolling mill is used; the specific control means and conditions include:

[0133] ① For the F1-3 stand, the distances between the tail of the strip and the centerline of the rolling mill are 0.8m, 0.8m, and 1.5m, respectively. When the actual thickness is detected to be lower than the reference thickness by 0.10mm, 0.08mm, and 0.10mm, respectively, roll gap compensation is immediately initiated.

[0134] ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail end of the rolling mill is 0.05mm;

[0135] (3) mill load distribution and roll cooling parameters;

[0136] Mill load distribution type: ① F1-2 stands adopt reduction ratio distribution, with F1's reduction ratio being 60% and F2's reduction ratio being 45%, and meeting the requirements of F1's bite angle of 15.2° and F2's bite angle of 13.7°; ② F3-7 stands adopt rolling force distribution, with the rolling force set in descending order; the unit rolling forces of F1-7 meet the following requirements: F1 is 2.3t / mm, F2 is 1.69t / mm, F3 is 1.52t / mm, F4 is 1.36t / mm, F5 is 1.22t / mm, F6 is 1.26t / mm, and F7 is 1.05t / mm;

[0137] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5300m 3 / h, and the cooling water volume of the upper working roll is 45% of the total water volume, and the cooling water volume of the lower working roll is 55% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 54% of the total water volume, the working roll temperature at the bottom of the machine is 56℃, the temperature difference along the length of the roll body is 9℃, and the average temperature difference of the roll surface is 1℃;

[0138] (4) The layer cooling feedforward compensation function based on strip speed prediction is put into use, and the water volume per unit length of the layer cooling rough adjustment section is controlled at 130m 3 / h·m, the water volume per unit length of the downward spray is controlled at 170m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 90m 3 / h·m, the water volume per unit length of the downward spray is controlled at 150m 3 / h·m; the maximum rolling speed for pickled steel is 14m / s, and the response time for opening and closing the laminar cooling water valve is 0.5s. Based on the above control requirements, conventional methods are used to use time-speed diagrams to predict the future speed of the strip in real time and transmit them to the laminar cooling secondary model to calculate the laminar flow header configuration and cooling compensation water volume in advance. The control accuracy of the laminar intermediate temperature and coiling temperature is 98.5% and 98.6%, respectively.

[0139] (5) The winding adopts anti-adhesion pinch rollers, and the surface and cross-section hardness uniformity meets the requirements of HRC54~56;

[0140] Pickled steel production is stable, with a roll change cycle of 1,260 tons and a work roll surface quality rating of A. Slab casting speed is 5.5 m / min, with a slab thickness of 75 mm. Pickled steel production efficiency has increased by 16%, process costs have been reduced by 40 yuan / ton, and the full-process spot rate is 1.5%.

[0141] Comparative Example 1

[0142] A short-process production line is used to produce pickled steel SPHC with a specification of 1.2mm*1250mm. The chemical composition, by mass percentage, includes: C 0.05%, Si 0.12%, Mn 0.45%, P 0.013%, S 0.006%, Cr 0.32%, Ti 0.075%, Nb 0.030%, Als 0.05%, N 0.006%, and the balance is Fe and unavoidable impurities.

[0143] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0144] (1) Roll gap compensation at the head of the rolling mill

[0145] ① The automatic compensation function of the roll gap at the head of the rolling mill is not used;

[0146] ②F1-7 frame, automatic thickness control function is fully used;

[0147] (2) Roll gap compensation at the tail end of the rolling mill

[0148] The roll gap compensation function at the tail end of the rolling mill is not used;

[0149] (3) mill load distribution and roll cooling parameters;

[0150] Rolling mill load distribution type: F1 to 7 stands all adopt reduction ratio distribution. The unit rolling forces of F1 to 7 are: F1 is 2.3t / mm, F2 is 2.4t / mm, F3 is 2.3t / mm, F4 is 2.2t / mm, F5 is 1.8t / mm, F6 is 1.5t / mm, and F7 is 1.3t / mm.

[0151] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5400m 3 / h, and the cooling water volume of the upper working roll is 50% of the total water volume, and the cooling water volume of the lower working roll is 50% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 45% of the total water volume, the working roll temperature at the bottom of the machine is 77℃, the temperature difference along the length of the roll body is 23℃, and the average temperature difference of the roll surface is 10℃;

[0152] (4) The conventional control method is used for layer cooling, and the water volume per unit length of the coarse adjustment section is controlled at 135m 3 / h·m, the water volume per unit length of the downward spray is controlled at 165m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 100m 3 / h·m, the water volume per unit length of the downward spray is controlled at 140m 3 / h·m; the maximum rolling speed of pickled steel is 14.5m / s, the opening and closing response time of the laminar cooling water valve is 1.0s, and the control accuracy of the laminar intermediate temperature and coiling temperature are 88.5% and 90.7% respectively;

[0153] (5) Ordinary pinch rollers are used for winding, and the surface and cross-section hardness uniformity is HRC50-60;

[0154] Pickled steel production was unstable, with a roll change cycle of only 600 tons, and the work roll surface quality rating of C. The slab casting speed was 4.2 m / min, and the slab thickness was 60 mm. Pickled steel production efficiency was low, process costs were high, and the overall spot rate was as high as 22.5%.

[0155] Comparative Example 2

[0156] A short-process production line is used to produce pickled steel SAPH440 with a specification of 1.8mm*1250mm. The chemical composition, by mass percentage, includes: C 0.045%, Si 0.11%, Mn 0.6%, P 0.012%, S 0.005%, Cr 0.35%, Ti 0.08%, Nb 0.025%, Als 0.05%, N 0.005%, and the balance is Fe and unavoidable impurities.

[0157] The controlled rolling and controlled cooling process used specifically includes the following steps:

[0158] (1) Roll gap compensation at the head of the rolling mill

[0159] ① The automatic compensation function of the roll gap at the head of the rolling mill is not used;

[0160] ②F1-7 frame, automatic thickness control function is fully used;

[0161] (2) Roll gap compensation at the tail end of the rolling mill

[0162] The roll gap compensation function at the tail end of the rolling mill is not used;

[0163] (3) mill load distribution and roll cooling parameters;

[0164] Rolling mill load distribution type: F1 to 7 stands all adopt reduction ratio distribution. The unit rolling forces of F1 to 7 are: F1 is 2.1t / mm, F2 is 2.2t / mm, F3 is 2.0t / mm, F4 is 1.8t / mm, F5 is 1.6t / mm, F6 is 1.3t / mm, and F7 is 1.35t / mm.

[0165] The roll cooling parameters used include: ① The total cooling water volume of the finishing work roll is 5100m 3 / h, and the cooling water volume of the upper working roll is 50% of the total water volume, and the cooling water volume of the lower working roll is 50% of the total water volume; ② The cooling water volume of the F2~4 working rolls accounts for 46% of the total water volume, the working roll temperature at the bottom of the machine is 75℃, the temperature difference along the length of the roll body is 20℃, and the average temperature difference of the roll surface is 7℃;

[0166] (4) The conventional control method is used for layer cooling, and the water volume per unit length of the coarse adjustment section is controlled at 140m 3 / h·m, the water volume per unit length of the downward spray is controlled at 160m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 110m 3 / h·m, the water volume per unit length of the downward spray is controlled at 130m 3 / h·m; the maximum rolling speed of pickled steel is 13m / s, the opening and closing response time of the laminar cooling water valve is 1.2s, and the control accuracy of the laminar intermediate temperature and coiling temperature are 90.3% and 91.2% respectively;

[0167] (5) Ordinary pinch rollers are used for winding, and the surface and cross-section hardness uniformity is HRC50~59;

[0168] Pickled steel production was unstable, with a roll change cycle of only 550 tons, and the work roll surface quality rating of C. The slab casting speed was 4.2 m / min, and the slab thickness was 60 mm. Pickled steel production efficiency was low, process costs were high, and the overall spot rate was as high as 21.6%.

[0169] This invention significantly improves the production efficiency of thin-gauge pickled steel in a short process. The roll-changing cycle has been increased from the traditional 600 tons to over 1,100 tons, and the work roll surface quality has been rated A. The slab casting speed has been increased from 4.2 m / min to 5.5 m / min, and the slab thickness has been increased from 60 mm to 75 mm. This has increased production efficiency by over 10%, reduced process costs by over 20 yuan per ton, and reduced the spot rate of the entire process to below 5%, enhancing the competitiveness of related products in the market and on the user side.

[0170] For researchers and technicians in this field, it is easy to improve and modify the present invention without departing from the technology of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. The present invention is not limited to the above-mentioned embodiments, and any changes that do not depart from the scope of protection of the present invention are covered by the claims.

Claims

1. A method for improving the production efficiency of short-process thin-gauge pickled steel, characterized in that: Its controlled rolling and controlled cooling technology includes optimizing the compensation parameters of the head and tail roll gaps of the rolling mill, optimizing the load distribution of the rolling mill and the cooling parameters of the rolls, developing a feedforward compensation layer cooling technology based on strip speed prediction, and improving the coiling pinch rolls. The main control requirements are as follows: (1) Roll gap compensation at the head of the rolling mill: When the rolling thickness is ≤3.0mm, the automatic compensation technology for the roll gap at the head of the rolling mill is used. The specific control means and conditions include: ① For F4-7 stands, the thickness of the rolling mill head is embedded 0.3-1.0mm; ② For F1 to 7 stands, the automatic thickness control function of the strip head is not used; ③ After the load of F1~7 stands is established, the thickness embedded value is reset to zero within the control sequence of 0.2~0.6s, and the rolling mill roll gap adjustment rate is controlled to 1.0~2.0mm / s. At the same time, the thickness automatic control function is automatically put into use to ensure that the finished product thickness meets the standard; (2) Compensation of the tail roll gap of the rolling mill: When the rolling thickness is ≤3.0mm, the automatic compensation technology of the tail roll gap of the rolling mill is put into use. The specific control means and conditions include: ① For F1-3 stands, when the distance between the tail of the strip and the center line of the mill is 0.8-1.5m, and the actual thickness detected is 0.08-0.12mm lower than the threshold value of the reference thickness, the roll gap compensation is immediately started; ② For F1~3 stands, the automatic compensation adjustment range of the roll gap at the tail of the rolling mill is 0.05~0.2mm; (3) Optimize mill load distribution and roll cooling parameter control Mill load distribution type: ①F1~2 stands adopt reduction ratio distribution, ②F3~7 stands adopt rolling force distribution; Roll cooling parameter control: including the total cooling water volume of the finishing work rolls, the proportion of cooling water volume of the F2-4 stand work rolls to the total water volume, the temperature of the F2-4 work rolls at the bottom of the machine, the temperature difference of the F2-4 work rolls along the length direction, and the average temperature difference of the upper and lower work rolls of the F2-4 stand; (4) Use of layer cooling feedforward compensation technology based on strip speed prediction The layer cooling consists of a coarse adjustment section, an air cooling section and a fine adjustment section. The water volume per unit length in the coarse adjustment section is controlled at 110-130m 3 / h·m, the water volume per unit length of the downward spray is controlled at 170~190m 3 / h·m; the water volume per unit length of the fine-tuning section is controlled at 80~100m 3 / h·m, the water volume per unit length of the downward spray is controlled at 140~160m 3 / h·m; the maximum rolling speed is controlled to not exceed 17m / s, and the response time for opening and closing the layer cooling water valve is ≤0.8s. Based on the above control requirements, the time-speed diagram is used to predict the future speed of the strip in real time and transmit it to the layer cooling secondary model to calculate the laminar flow header configuration and cooling compensation water volume in advance; (5) Anti-adhesion pinch rollers are used for winding.

2. The method according to claim 1, characterized in that By adopting the mill head roll gap compensation step described in step (1), the thickness of the strip head tip is measured to increase by 0.08 to 0.10 mm.

3. The method according to claim 1, characterized in that By adopting the mill tail roll gap compensation step described in step (2), the actual measured strip tail tongue length is shortened by 25-35%.

4. The method according to claim 1, wherein Add hydraulic valve groups to F1~3 frames.

5. The method according to claim 1, wherein In the step of allocating the reduction rates of the F1 and F2 frames, the reduction rate of F1 is 60-65%, and the reduction rate of F2 is 45-50%. Meanwhile, the bite angle of F1 is ≤17.5°, and the bite angle of F2 is ≤15°.

6. The method according to claim 1, characterized in that The rolling force distribution of the F3 to F7 stands is set in a descending order.

7. The method according to claim 1, characterized in that In the control requirement (3), the unit rolling forces of F1 to 7 are ensured to be: F1≤2.6t / mm, F2≤1.9t / mm, F3≤1.7t / mm, F4≤1.5t / mm, F5≤1.4t / mm, F6≤1.3t / mm, F7≤1.2t / mm.

8. The method according to claim 1, characterized in that The roller cooling parameter control requirements include: ① The total cooling water volume of the finishing rolling work roll is 5100~5600m 3 / h, and the cooling water volume of the upper working roll is 42-45% of the total water volume, and the cooling water volume of the lower working roll is 55-58% of the total water volume; ② The cooling water volume of the working rolls of F2-4 frames accounts for 52-58% of the total water volume; ③ The bottom machine temperature of F2-4 working rolls is ≤68℃, the temperature difference of the length direction of the roller body of F2-4 working rolls is ≤15℃, and the average temperature difference of the upper and lower working roll surfaces of F2-4 working rolls is ≤3℃.

9. The method according to claim 1, characterized in that The chemical composition of the pickled steel, calculated by mass percentage, includes: C 0.03-0.07%, Si 0.11-0.3%, Mn 0.30-1.3%, P≤0.015%, S≤0.006%, Cr 0.30-0.55%, Ti 0.035-0.11%, Nb 0.02-0.05%, Als 0.02-0.06%, N≤0.006%, and the balance is Fe and unavoidable impurities.

10. The method according to claim 1, characterized in that The main chemical components of the anti-sticking pinch roller, calculated by mass percentage, meet the following requirements: C 0.2-0.4%, Si 0.6-0.8%, Mn 1.8-2.2%, Cr 6.5-7.5%, Mo 1.2-1.7%, V 0.3-0.7%, W 1.0-1.4%, P≤0.016%, S≤0.005%, Als 0.01-0.05%, N≤0.005%, and the balance is Fe and unavoidable impurities.