Production process and system of ultra-thin cold-rolled strip steel

Abstract

The invention relates to a production technology and system of ultra-thin cold-rolled strip steel. The production technology of the ultra-thin cold-rolled strip steel comprises the steps that raw material strip steel is subjected to acid pickling; carrying out cold rolling treatment on the raw material strip steel subjected to acid pickling by utilizing a five-rack continuous rolling mill to obtain cold-rolled strip steel; the cold-rolled strip steel is subjected to trimming shear treatment and rolling treatment in sequence, and multiple cold-rolled steel coils are obtained; taking a part of cold-rolled steel coils as first-class products; the other part of cold-rolled steel coils are subjected to unwinding treatment and then heated to the preset temperature, and preheated strip steel is obtained; warm rolling treatment is conducted on the preheated strip steel, and warm-rolled strip steel is obtained; and the warm-rolled strip steel is subjected to trimming shear treatment and rolling treatment in sequence, a warm-rolled steel coil is obtained, and the warm-rolled steel coil serves as a second-class product. According to the invention, ultra-thin cold-rolled strip steel products with two thickness specifications and the thickness below 0.2 mm can be produced, the production rhythm and the production efficiency can be improved, the production cost is reduced, and the thickness precision of the products is improved.

Description

Technical Field

[0001] This invention relates to the field of rolling and forming equipment for ultra-thin steel strips, and more particularly to a production process and system for ultra-thin cold-rolled steel strips. Background Technology

[0002] In existing specifications, ultra-thin steel strips typically refer to steel strips with a thickness between 0.15mm and 5mm. Due to their high strength and hardness, as well as good flexibility and plasticity, ultra-thin steel strips are generally made of high-strength steel and have excellent strength. They are widely used in the automotive, aerospace and other fields to manufacture automotive parts and mechanical parts. For thicker steel strips within the range of ultra-thin steel strips, the rolling process for ultra-thin steel strips with a thickness between 3 and 5 mm typically only produces rolled steel strips with a uniform cross-section. The cold rolling or hot rolling technology and equipment for this type of ultra-thin steel strip are relatively mature. However, for ultra-thin steel strips with irregular cross-sections, the production difficulty and numerous rolling defects have been a persistent challenge. Nevertheless, this type of ultra-thin steel strip with a thickness between 3 and 5 mm has broad application prospects in engineering fields such as construction, automotive manufacturing, and infrastructure construction. By setting different cross-sectional thicknesses, the thickness of the ultra-thin steel strip can be appropriately adjusted according to the stress requirements of the structure, thereby minimizing the self-weight of the structure while ensuring structural strength and effectively saving raw material usage.

[0003] For example, existing patent CN101811134A relates to a manufacturing method for preventing edge cracking in low-carbon cold-rolled ultra-thin strip steel. The method includes the following steps in sequence: smelting, slab heating, rough rolling, finish rolling, cooling, coiling, pickling, cold rolling, annealing, and finishing edge trimming. The steel coil is not trimmed during pickling, and its edges are kept rounded during the cold rolling process. The temperature difference between the slab and the surrounding slab during slab heating is ≤40℃. The side pressure during rough rolling is ≤50mm. The final rolling temperature during finish rolling is 880~920℃, and the side pressure of the F1 stand auxiliary vertical roll F1E is 3~10mm. The cooling is a laminar flow cooling with rapid initial cooling at a rate of 15~30℃ / s. The coiling temperature is 650~710℃. The single-sided shearing amount during edge trimming is controlled to be 5~7mm. The cold-rolled finished strip has a thickness of 0.15–0.45 mm and a reduction rate of 87.1%–95%. This patent can solve the problem of edge cracking in ultra-thin strips in the prior art.

[0004] Existing patent CN102172635A relates to a method for controlling the cross-sectional shape of hot-rolled strip steel for ultra-thin plates produced by a reversible cold rolling mill. The method includes hot-rolled strip steel with an elongated elliptical cross-section, comprising a middle section and an edge section. The middle section has a convexity. As the strip width B changes, the convexity value C40 and the wedge value W40 satisfy the following relationships: ① (1215+1015) / (1215-1015)≤C40≤40+(B-1015)×(45-40) / (1215-1015); ② W40≤50%C40. This patent is convenient to operate, stable in use, and has good consistency, significantly reducing the incidence of edge cracking accidents in ultra-thin cold-rolled plates and lowering costs.

[0005] Existing patent CN102179407A relates to a method for preparing hot-rolled strip steel that can avoid edge cracking during the rolling of ultra-thin strip steel, including: (1) smelting process: desulfurization of molten iron, smelting in a converter, argon blowing treatment at an argon station, and continuous casting into slabs; (2) hot rolling process: heating the slab to 1210~1260℃, with a temperature difference of ≤30℃ between the two plates; then rough rolling and finish rolling are performed. When rough rolling a slab with a width of B, the side pressure ΔB is controlled by the following formula: 50≥ΔB≥35×B / 1250(B-1050) / (1250-1050)+35×B / 1050×(1250-B) / (1250-1050); finally, the strip is coiled to obtain the final product. This patent is simple and easy to implement, stable in use, and has good uniformity. It reduces alloy costs and shortens the production cycle. The SPHC hot-rolled strip steel obtained by this method has a significant effect on preventing edge cracking of ultra-thin cold-rolled plates.

[0006] However, the above three patents can only be used for rolling extremely thin strips of one type of steel, and the versatility of the process is not high.

[0007] For example, existing patent CN220999758U belongs to the field of stainless steel strip production technology, specifically involving a roller structure for a continuous production line of ultra-thin strip steel, including a roller mandrel and a roller. The roller has a hollow structure, and both ends of the roller are provided with external support plates. Each external support plate is provided with a first shaft hole and multiple first through holes. The roller mandrel is disposed in the hollow cavity of the roller and its two ends are respectively disposed through the first shaft holes on both sides. The roller mandrel has a hollow structure, and both ends of the roller mandrel are equipped with solid roller necks. The roller mandrel and roller of this patent adopt a hollow structure, which can reduce the weight of the roller structure, reduce the rotational inertia of the roller, thereby reducing the tension fluctuation of ultra-thin strip steel during acceleration and deceleration, improving the product quality and production efficiency of ultra-thin strip steel, and avoiding quality defects and strip breakage in ultra-thin strip steel.

[0008] Existing patent CN 216324176 U discloses a roll system for a 450mm wide Sendzimir 20-roll mill, including a gate, an upper roll system, and a lower roll system. Both the upper and lower roll systems include work rolls, a first intermediate roll group, a second intermediate roll group, and a backing roll group. The first intermediate roll group includes two intermediate rolls, the second intermediate roll group includes a follower roll and a drive roll, and the backing roll group includes four backing rolls. The diameter of the work roll is Φ71.312mm~Φ86.821mm, the diameter of the intermediate roll is Φ85mm~Φ95mm, the diameter of the follower roll is Φ130mm~Φ137mm, and the diameter of the backing roll is Φ224.99mm. Each backing roll is provided with a fixing strip and a clamping mechanism on both sides. This patent solves the problem in the prior art where the rigidity of the rolls decreases in both the transverse and longitudinal directions due to the small roll diameter when rolling extremely thin stainless steel strips using a 450mm wide Sendzimir 20-roll mill.

[0009] Existing patent CN216857750U discloses an experimental rolling mill suitable for ultra-precision ultra-thin strip rolling processes. It includes a rolling mill base mounted on a civil engineering foundation. A rolling mill is fixed at the center of the base. Two identical process platforms, a left process platform and a right process platform, are symmetrically arranged about the rolling mill and also fixed to the base. A rolling mill cover is positioned directly above the base, covering the two process platforms and the rolling mill. A main drive unit is installed on the drive side of the rolling mill, and rolling mill piping is arranged around the edge of the base on the drive side. Many core components of the experimental rolling mill are connected as a whole via the rolling mill base before being connected to the civil engineering foundation. This integrated construction method not only provides sufficiently high installation accuracy for ultra-precision ultra-thin strip rolling but also greatly improves construction efficiency.

[0010] However, in the above three patents, the equipment is not closely integrated with the production process. In actual production, the equipment may require precise debugging to produce ultra-thin strips.

[0011] For example, existing patent CN 209680797 U discloses a production system for ultra-thin oriented silicon steel strip, which includes an uncoiling machine, a rolling mill, an alkaline washing tank, a water washing device, a dryer, a heat treatment furnace, a cooling device, a painting device, a drying furnace, a sintering furnace, and a winding machine arranged sequentially along the production direction of the ultra-thin oriented silicon steel strip; the outlet of the heat treatment furnace is connected to the inlet of the cooling device. Beneficial effects: The connection relationship of this patent is simple and easy to implement, greatly simplifying the production process of ultra-thin oriented silicon steel. The manufacturing method is simple and effective, featuring a short process, easy control, and low energy consumption; the ultra-thin oriented silicon steel strip prepared by this system meets the requirement of extremely thin thickness while improving magnetic properties, achieving the required service performance.

[0012] Existing patent CN 119870148 A provides a cold rolling method for high-precision ultra-thin strip special steel, the cold rolling method comprising the following steps: (1) the thickness of the steel coil before cold rolling is 2.5mm to 3.0mm, and a cold rolling production method using a pickling-continuous rolling combined unit and a 20-roll combination is adopted; (2) a two-stage cold rolling method is adopted, the first cold rolling uses a 5-stand four-roll continuous rolling mill to roll the raw material to an intermediate thickness, and the second cold rolling uses a 20-roll reversible mill to roll the intermediate thickness to the target thickness; (3) in the first cold rolling, the 5-stand four-roll mill rolls the raw material from a thickness of 2.5mm to 3.0mm to an intermediate thickness of 0.5mm to 0.8mm, with a total reduction rate of 65% to 80%; (4) the second cold rolling uses a 20-roll reversible mill for three-pass cold rolling; the reduction rate of the first and second passes is controlled at 30% to 36%, and the reduction rate of the third pass is controlled at 20% to 28%; (5) the rolled product is 0.19mm to 0.25mm. Thickness control accuracy is ±1μm.

[0013] However, for special steels with thicknesses below 0.2mm, traditional five-stand continuous rolling mills have limited control capabilities, resulting in limited control over thickness and strip thickness variation, making it impossible to obtain ultra-thin products that meet high-precision thickness requirements. Alternatively, traditional pickling and 20-roll mill production processes are relatively expensive and time-consuming. Neither approach can simultaneously meet the requirements of low production cost and high strip precision. Summary of the Invention

[0014] The purpose of this invention is to provide a production process and system for ultra-thin cold-rolled strip steel, which can produce ultra-thin cold-rolled strip steel products with two thickness specifications and a thickness of less than 0.2 mm, and can improve production speed and efficiency, reduce production costs, and improve product thickness accuracy.

[0015] The objective of this invention can be achieved using the following technical solutions:

[0016] This invention provides a production process for ultra-thin cold-rolled strip steel, comprising:

[0017] Pickling is performed on raw steel strips with a thickness of 0.7-1.0 mm;

[0018] Pickled raw strip steel is cold-rolled using a five-stand continuous rolling mill to obtain cold-rolled strip steel; wherein the roll diameter of the five stands in the five-stand continuous rolling mill is ≤400mm and the thickness of the cold-rolled strip steel is less than 0.2mm.

[0019] The cold-rolled strip steel is subjected to edge trimming and coiling processes in sequence to obtain multiple cold-rolled steel coils.

[0020] A portion of cold-rolled steel coils will be classified as Category 1 products.

[0021] Another portion of the cold-rolled steel coils is unwound and then heated to a preset temperature to obtain preheated steel.

[0022] The preheating strip steel is subjected to warm rolling treatment to obtain warm rolled strip steel; wherein, during the warm rolling treatment, the preheating strip steel is subjected to 3-5 passes of reciprocating rolling using a 20-roll mill;

[0023] The warm-rolled strip steel is subjected to edge trimming and coiling processes in sequence to obtain warm-rolled steel coils, which are classified as the second type of product.

[0024] In a preferred embodiment of the present invention, the roll diameters of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll in the five-stand continuous rolling mill are all larger than the roll diameter of the third stand roll, and the difference is ≤80mm; the roll changing cycles of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll are the same, and are 1.5-2.5 times the roll changing cycle of the third stand roll.

[0025] In a preferred embodiment of the present invention, the roll diameters of the first stand roll, second stand roll, fourth stand roll, and fifth stand roll in the five-stand continuous rolling mill are 340-380 mm, the roll diameter of the third stand roll is 300 mm, and the roll changing cycle of the first stand roll, second stand roll, fourth stand roll, and fifth stand roll is twice the roll changing cycle of the third stand roll.

[0026] In a preferred embodiment of the present invention, the thickness of the cold-rolled strip is 0.15-0.19 mm.

[0027] In a preferred embodiment of the present invention, the fourth stand roll in the five-stand continuous rolling mill is a conical work roll; or, both the fourth stand roll and the fifth stand roll in the five-stand continuous rolling mill are conical work rolls.

[0028] In a preferred embodiment of the present invention, the total reduction rate of the five-stand continuous rolling mill does not exceed 85%, the third stand roll in the five-stand continuous rolling mill is a cylindrical roll with a reduction rate of 20% to 35%, and the fifth stand roll is a tapered roll with a reduction rate of 20% to 28%.

[0029] In a preferred embodiment of the present invention, an intermediate annealing process is included between the edge trimming and coiling processes of the cold-rolled strip steel; the annealing temperature of the intermediate annealing process is 850-950°C, and the holding time after annealing is 3-5 minutes.

[0030] In a preferred embodiment of the present invention, the preheating steel is heated by electromagnetic induction, and the preset temperature is 330-370°C.

[0031] In a preferred embodiment of the present invention, the thickness of the preheating steel is less than 0.17 mm, and the preheating steel is subjected to three reciprocating rolling passes using a 20-roll mill during the warm rolling process; in the three reciprocating rolling passes, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the overall reduction rate is controlled at 38-46%.

[0032] In a preferred embodiment of the present invention, the thickness of the preheating steel is greater than 0.18 mm. During the warm rolling process, the preheating steel is subjected to 5 passes of reciprocating rolling using a 20-roll mill. In the 5 passes of reciprocating rolling, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the reduction rates of the fourth and fifth passes are both controlled at 10-12%, with the overall reduction rate controlled at 50-53%.

[0033] In a preferred embodiment of the present invention, a continuous annealing process is further included between the edge trimming and coiling processes of the warm rolled strip; the annealing temperature of the continuous annealing process is 800-900°C, and the annealing time is 5-8 minutes.

[0034] The present invention also provides an ultra-thin cold-rolled strip steel production system, employing the above-mentioned ultra-thin cold-rolled strip steel production process, the ultra-thin cold-rolled strip steel production system comprising:

[0035] A cold rolling production line includes a first uncoiling mechanism, a pickling tank, a five-stand continuous rolling mill, a first edge trimming shear, and a first coiling mechanism arranged in sequence.

[0036] A warm rolling production line is used to perform warm rolling on a portion of the cold-rolled steel coils obtained from a cold rolling production line. The warm rolling production line includes a second uncoiling mechanism, a preheating device, a 20-roll mill, a second edge trimming shear, and a second coiling mechanism arranged in sequence.

[0037] As described above, the production process and system for ultra-thin cold-rolled strip steel of the present invention, by using roll diameters of ≤400mm for each stand of the five-stand continuous rolling mill in the cold rolling process, can obtain strip steel with a thickness of less than 0.2mm after cold rolling. This strip steel can be directly used as an ultra-thin cold-rolled strip steel product, or it can be preheated and then subjected to warm rolling treatment in a twenty-roll mill to obtain an even thinner ultra-thin cold-rolled strip steel product. Furthermore, by using the production process of this application, two thickness specifications of ultra-thin cold-rolled strip steel products with a thickness of less than 0.2mm can be produced. Furthermore, since the production speed of the five-stand continuous rolling mill is relatively fast, while that of the twenty-roll mill is relatively slow, the cold-rolled steel coils obtained by the present invention after cold rolling on the five-stand continuous rolling mill can be directly used as the first type of product, or they can be further processed by warm rolling on the twenty-roll mill to obtain the second type of product. By controlling the ratio of the number of cold-rolled steel coils used as the first type of product to the number of cold-rolled steel coils undergoing subsequent warm rolling based on relevant parameters such as the production speed of the five-stand continuous rolling mill and the twenty-roll mill, the production process can be more closely matched, and steel accumulation is less likely to occur. This improves the production rhythm and efficiency, and reduces production costs.

[0038] In addition, preheating the cold-rolled steel coil after uncoiling before entering the warm rolling process can further enhance the shaping of the strip, allowing the strip to be rolled more times on a 20-roll mill without breaking, which is more conducive to obtaining thinner strip products. Moreover, the accuracy of the product thickness can also be guaranteed after more rolling passes. Attached Figure Description

[0039] The following figures are intended only to illustrate and explain the present invention and do not limit the scope of the invention. Wherein:

[0040] Figure 1 This is a schematic diagram of the cold rolling production line provided by the present invention.

[0041] Figure 2 This is a schematic diagram of the warm rolling production line provided by the present invention.

[0042] Explanation of icon numbers:

[0043] 11. First unwinding mechanism; 12. Pickling tank; 13. Five-stand continuous rolling mill; 14. First edge trimming shear device; 15. First continuous annealing furnace; 16. First winding mechanism;

[0044] 21. Second unwinding mechanism; 22. Preheating device; 23. Twenty-roll mill; 24. Second edge trimming shear device; 25. Second winding mechanism. Detailed Implementation

[0045] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0046] like Figure 1 and Figure 2 As shown, this application provides a production process for ultra-thin cold-rolled strip steel, including:

[0047] Pickling is performed on raw steel strips with a thickness of 0.7-1.0 mm;

[0048] Pickled raw strip steel is cold-rolled using a five-stand continuous rolling mill 13 to obtain cold-rolled strip steel; wherein, the roll diameter of the five stands in the five-stand continuous rolling mill 13 is ≤400mm, and the thickness of the cold-rolled strip steel is less than 0.2mm;

[0049] The cold-rolled strip steel is subjected to edge trimming and coiling processes in sequence to obtain multiple cold-rolled steel coils.

[0050] A portion of cold-rolled steel coils will be classified as Category 1 products.

[0051] Another portion of the cold-rolled steel coils is unwound and then heated to a preset temperature to obtain preheated steel.

[0052] The preheating strip steel is subjected to warm rolling treatment to obtain warm rolled strip steel; wherein, during the warm rolling treatment, the preheating strip steel is subjected to 3-5 passes of reciprocating rolling using a 20-roll mill 23;

[0053] The warm-rolled strip steel is subjected to edge trimming and coiling processes in sequence to obtain warm-rolled steel coils, which are classified as the second type of product.

[0054] Therefore, by using roll diameters of ≤400mm for each stand of the five-stand continuous rolling mill 13 in the cold rolling process, this application can obtain strip steel with a thickness of less than 0.2mm after cold rolling. This strip steel can be directly used as an ultra-thin cold-rolled strip steel product, or it can be preheated and then fed into the twenty-roll mill 23 for warm rolling to obtain an even thinner ultra-thin cold-rolled strip steel product. Furthermore, by using the production process of this application, two thickness specifications of ultra-thin cold-rolled strip steel products with a thickness of less than 0.2mm can be produced. Furthermore, since the production speed of the five-stand continuous rolling mill 13 is relatively fast and the production speed of the twenty-roll mill 23 is relatively slow, the cold-rolled steel coils obtained by the cold rolling process of the five-stand continuous rolling mill 13 can be directly used as the first type of product, or they can be further processed by the twenty-roll mill 23 to obtain the second type of product. By controlling the ratio of the number of cold-rolled steel coils used as the first type of product to the number of cold-rolled steel coils undergoing subsequent warm rolling based on the production speed and other relevant parameters of the five-stand continuous rolling mill 13 and the twenty-roll mill 23, the production process can be more closely matched, and steel accumulation is less likely to occur. This improves the production rhythm and efficiency, and reduces the production cost.

[0055] In addition, preheating the cold-rolled steel coil after uncoiling before entering the warm rolling process can further enhance the shaping of the strip, allowing the strip to be rolled more times on the 20-roll mill 23 without breaking, which is more conducive to obtaining thinner strip products. Moreover, the accuracy of the product thickness can also be guaranteed after more rolling passes.

[0056] In the specific implementation, during the cold rolling step, the working parameters of the five-stand continuous rolling mill 13 are set according to the size requirements of the ultra-thin strip steel products produced. The working parameters include: raw material thickness, production speed, inter-stand reduction ratio distribution, roll structure parameters of each stand, and emulsion parameters of each stand.

[0057] Optionally, the emulsion spraying of the five-stand continuous rolling mill 13 is controlled separately, and the emulsion spraying pressure is gradually reduced during the rolling process of each strip after the pre-rolling of the five-stand continuous rolling mill 13.

[0058] The emulsion parameters for each stand are as follows: The emulsion concentration used in the first four stands of the five-stand continuous rolling mill needs to be configured uniformly through the control system.

[0059] The raw materials used in the cold rolling process come from products of different production lines. The raw strip steel is pre-rolled on a five-stand continuous rolling mill 13 to produce transition strip steel (i.e., the aforementioned cold-rolled strip steel) that can be warm-rolled on a twenty-high rolling mill 23. The thickness of the raw strip steel cannot exceed the maximum thickness of the raw materials that the five-stand continuous rolling mill 13 can handle. After the raw strip steel is rolled, the transition strip steel is produced on the five-stand continuous rolling mill 13 according to a preset cold rolling program.

[0060] Alternatively, the reduction ratio distribution between stands of the five-stand continuous rolling mill 13 is as follows: the total reduction ratio of the five-stand continuous rolling mill 13 does not exceed 85%, the third stand rolls in the five-stand continuous rolling mill 13 are cylindrical rolls with a reduction ratio of 20% to 35%, and the fifth stand rolls are tapered rolls with a reduction ratio of 20% to 28%. This reduction ratio parameter ensures normal operation of the equipment and the achievement of the required strip thickness. In the reduction ratio distribution of the five-stand continuous rolling mill 13, the reduction ratio of each stand gradually decreases.

[0061] Alternatively, the structural parameters of the rolls of each stand of the five-stand continuous rolling mill 13 are as follows: the length of any roll of any stand of the five-stand continuous rolling mill 13 is not less than 1400 mm.

[0062] Alternatively, the roll diameter parameters of each work roll of the five-stand continuous rolling mill 13 are as follows: the roll diameter of the first stand roll, the second stand roll, the fourth stand roll and the fifth stand roll is ≤400mm, and the roll diameter of the third stand roll is controlled at 300±5mm.

[0063] Further optionally, in the five-stand continuous rolling mill 13, the roll diameters of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll are all larger than the roll diameter of the third stand roll, and the difference is ≤80mm; the roll changing cycles of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll are the same, and are 1.5-2.5 times the roll changing cycle of the third stand roll.

[0064] For example, in the five-stand continuous rolling mill 13, the roll diameters of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll are 340-380 mm, and the roll diameter of the third stand roll is 300 mm. The roll changing cycle of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll is twice the roll changing cycle of the third stand roll.

[0065] Within this roll diameter parameter, on the one hand, very thin cold-rolled strip steel can be obtained after rolling on a five-stand continuous rolling mill, for example, the thickness of cold-rolled strip steel can be 0.15-0.19mm, which can meet the demand for producing extremely thin cold-rolled strip steel with a thickness of less than 0.2mm; on the other hand, by controlling the roll diameter, the roll changing cycle of each stand can be controlled, so that the roll changing cycle of the first, second, fourth and fifth stands is the same, and is 1.5-2.5 times that of the roll changing cycle of the third stand, which is more conducive to saving maintenance costs, and can save overall roll changing time, with shorter downtime and higher production efficiency.

[0066] Alternatively, the fourth stand roll in the five-stand continuous rolling mill 13 may be a tapered work roll; or, both the fourth stand roll and the fifth stand roll in the five-stand continuous rolling mill 13 may be tapered work rolls.

[0067] Conical work rolls can be used to adjust the strip shape, replacing the leveling machine. Generally, when wide-width rolling (strip width ≥ 1250mm), conical work rolls are used on both the fourth and fifth stands; when the strip width is less than 1250mm, conical work rolls are used only on the fourth stand.

[0068] When tapered work rolls are used on both the fourth and fifth frames, optionally, the length of the tapered cylindrical structure at either end of the roller in the fourth and fifth frames along its axial direction is 80 to 120 mm. The difference between the radius of the axial end of the roller in the fourth frame and the radius of the cylindrical structure in its middle is 0.6 ± 0.2 mm, and the difference is 0.4 ± 0.2 mm for the fifth frame.

[0069] Furthermore, the conical work roll can be used to adjust the strip shape. According to product requirements and work roll reduction, the flattening elongation rate of the conical work roll is set, and the flattening rolling force, front and rear tension, and initial bending force are set. The strip shape is detected in real time using a contact-type strip shape meter at the mill exit to obtain the transverse tension distribution of intermediate products, determine whether there are any strip shape defects, and compare the detected strip shape with the target strip shape. When the deviation exceeds a certain range, the bending force and rolling force of the conical work roll are dynamically adjusted until the deviation is within the allowable range.

[0070] Specifically, when plate shape defects occur in intermediate products, the transverse tension of the strip will deviate. This transverse stress deviation of the strip is usually less than a certain critical value, which is determined by relevant formulas in elasticity. The transverse tension deviation values ​​of the edge and the middle are calculated separately. Based on the magnitude of the deviation, it is determined whether edge waviness defects and middle waviness defects will occur. For example, for a steel plate with a thickness of 2mm and a width of 1425mm, the critical stress is calculated to be 22.3MPa. At this time, the calculated stress in the middle is 30MPa, which may result in edge waviness defects on both sides.

[0071] Furthermore, the correspondence between the raw material thickness selection and the product thickness specification for producing ultra-thin strip steel using the five-stand continuous rolling mill 13 is as follows: when the product thickness specification is 0.17±0.01mm, the raw material thickness is 0.7mm; when the product thickness specification is 0.18±0.01mm, the raw material thickness is 0.8mm; and when the product thickness specification is 0.19±0.01mm, the raw material thickness is 0.9mm.

[0072] Alternatively, the production speed of the transition strip steel produced by the five-stand continuous rolling mill 13 should be greater than 850 m / min.

[0073] Further optionally, an intermediate annealing process may be included between the edge trimming and coiling processes of the cold-rolled strip.

[0074] Optionally, the annealing temperature for intermediate annealing is 850-950℃, and the holding time after annealing is 3-5 minutes.

[0075] Furthermore, before the pickling step, the process includes uncoiling the raw steel coil to obtain raw steel strip. The raw steel coil can be produced from other production lines and coiled by a corresponding winding mechanism.

[0076] After cold rolling to obtain cold-rolled strip steel using a five-stand continuous rolling mill 13, the strip steel is first subjected to edge trimming to remove edges that may crack, and then cut to a predetermined length. Next, it undergoes continuous annealing (i.e., the intermediate annealing process described above). After annealing, it is coiled by a corresponding coiling machine to obtain cold-rolled steel coils. The first coil is directly used as the first type of product, while the second coil undergoes subsequent warm rolling to become the second type of product.

[0077] For the obtained multi-roll cold-rolled steel coils, the number of coils as the first type of product and the number of coils entering the 23-roll mill for warm rolling treatment as the second type of product are allocated according to the actual situation. The number of first coils should be greater than the number of second coils. The specific ratio is set according to the actual situation. For example, in a specific case, the number of first coils to the number of second coils is 4:1.

[0078] Product allocation requires scheduling. When the thickness of cold-rolled strip (i.e., cold-rolled strip) is less than 0.16mm, it can be sold directly as a product (i.e., Category I product). When the thickness of cold-rolled strip is greater than 0.17mm, scheduling is carried out according to the product's intended use. A portion of the cold-rolled strip needs to undergo warm rolling to obtain strips with even thinner thicknesses. For example, if product scheduling is based on a single cold-rolling output of one million tons, the plant needs to be equipped with two 20-roll mills. According to the quota, 800,000 tons will be sold directly as Category I product, while 200,000 tons will undergo warm rolling to produce Category II products with even thinner thicknesses.

[0079] Alternatively, electromagnetic induction heating can be used for the preheated strip steel. During warm rolling, an induction heating coil is added to the front of the 20-roll mill 23 to improve the plasticity of the strip and prevent it from tearing during multi-pass rolling.

[0080] The preset temperature mentioned above should not be too high, and should be controlled between 330-370℃. Rolling strip steel at a temperature of 20-100℃ is usually called cold rolling. Since the temperature of the preheated strip steel is above 300℃, rolling it using a 20-roll mill 23 can be called warm rolling.

[0081] Furthermore, during the warm rolling process, the number of rolling passes is determined based on product requirements and raw material thickness (i.e., the thickness of the preheated steel strip, which is also equal to the thickness of the cold-rolled strip). When the raw material thickness is less than 0.17 mm, 3 rolling passes are used, and when the thickness is greater than 0.18 mm, 5 rolling passes are used.

[0082] Specifically, the thickness of the preheated strip steel is less than 0.17 mm. During the warm rolling process, the preheated strip steel is rolled in three passes using a 20-roll mill 23. In the three passes of reciprocating rolling, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the overall reduction rate is controlled at 38-46% to ensure the normal operation of the equipment and to control the product thickness (i.e., the obtained warm rolled strip steel) at 0.1±0.005 mm.

[0083] The thickness of the preheating steel is greater than 0.18 mm. During the warm rolling process, the preheating steel is rolled in 5 passes using a 20-roll mill 23. In the 5 passes of reciprocating rolling, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the reduction rates of the fourth and fifth passes are both controlled at 10-12%, with the overall reduction rate controlled at 50-53% to ensure the normal operation of the equipment and to control the product thickness at 0.09±0.005 mm.

[0084] Alternatively, a continuous annealing process can be included between the edge trimming and coiling of the warm-rolled strip. Continuous annealing after warm rolling increases the material's ductility and toughness.

[0085] Optionally, the annealing temperature for continuous annealing is 800-900℃, and the annealing time is 5-8 minutes.

[0086] Furthermore, when the product is made of silicon steel, an additional coating process is required after continuous annealing before it can be considered a finished product.

[0087] Furthermore, there are corresponding unwinding and rewinding mechanisms in front of and behind the 20-roll mill 23. The unwinding and rewinding mechanisms are located on both sides of the 20-roll mill 23, and the rewinding mechanism is located at the end of the rolling direction, which further accelerates the overall system capacity.

[0088] To better understand the above production process, two specific examples are provided below.

[0089] Example 1

[0090] The raw material before cold rolling is a hot-rolled coil with a product thickness of 0.7mm. The production method combines cold rolling and hot rolling using a pickling-continuous rolling mill and a 20-roll combination. The cold rolling process uses a five-stand continuous rolling mill 13 to roll the raw material to the initial thickness. The first three stands of the five-stand continuous rolling mill 13 all use cylindrical rolls, while the fourth and fifth stands are designed as tapered rolls with tapered ends along the axial direction. The production process is as follows:

[0091] When the thin strip product comes off the twin-roll thin strip production line, it is coiled into a coil by the winding mechanism as raw material steel coil. The steel coil is then transferred to the cold rolling workshop by a crane to start the subsequent cold rolling process.

[0092] The raw steel coil is first uncoiled by the uncoiling mechanism at the head (i.e., the first uncoiling mechanism 11) to obtain the raw steel strip;

[0093] As the rolling direction progresses, the raw strip gradually enters the pickling tank 12 for pickling to remove the surface oxide layer;

[0094] After passing through the pickling tank 12, the raw strip steel moves with the conveyor rollers to the area of ​​the five-stand continuous rolling mill 13 to begin cold rolling. Furthermore, in order to prevent excessive reduction from causing the strip steel to tear, the reduction rate between each stand is distributed as follows: the total reduction rate of the five-stand continuous rolling mill 13 does not exceed 85%, and the reduction rate of the cylindrical rolls of the third stand of the five-stand continuous rolling mill 13 is 25%, and the reduction rate of the conical rolls of the fifth stand is 20%. After rolling on the third stand, the thickness of the thin strip is reduced to 0.28±0.02mm, and after rolling on the fifth stand, the thickness of the thin strip is reduced to 0.17±0.01mm.

[0095] The edges of the cold-rolled strip obtained after 13 consecutive rolling on a five-stand continuous rolling mill will crack. It is transported to the edge cutting shearing area by conveyor rollers to remove the edges.

[0096] After the edge scrap is removed, the strip steel is annealed in a continuous annealing furnace (i.e., the first continuous annealing furnace 15) and then coiled into cold-rolled steel coils. The annealing temperature is controlled at 900±50℃, and the coils need to be held at that temperature for 3-5 minutes after annealing. A portion of the cold-rolled steel coils are then used directly as the first type of product, while the other portion is prepared for subsequent warm rolling. These coils are then rolled through a 20-roll mill 23 to become the thinner second type of product. The production speed of the cold-rolled strip steel produced by the above-mentioned five-stand continuous rolling mill 13 should be greater than 850 m / min.

[0097] Another portion of the cold-rolled steel coils enter the warm rolling production line through the uncoiling mechanism (i.e., the second uncoiling mechanism 21). The strip steel is first transported to the magnetic induction heating area by the conveyor, where it is heated to 360°C to obtain preheated steel.

[0098] The preheated steel, heated by magnetic induction heating, enters the rolling zone of the 20-roll mill 23 for three reciprocating rolling passes. The reduction rate of the first pass is controlled at 21-22%, the reduction rate of the second pass is controlled at 19-20%, the reduction rate of the third pass is controlled at 13-14%, the overall reduction rate is controlled at 39-40%, and the product thickness is controlled at 0.1±0.005mm.

[0099] After the third rolling pass is completed, the obtained warm-rolled strip enters the edge trimming shearing area along the rolling direction to remove edge waste and is coiled into a product, which can be used as the second type of product.

[0100] Example 2

[0101] The raw material before cold rolling comes from ESP endless rolling mill for producing silicon strip steel. The raw strip is silicon steel with a thickness of 0.8 mm and a width of 1250 mm. The Si content of the raw strip is 3.25%, and the Al content is 0.95%. The production method combines cold rolling and hot rolling using a pickling-continuous rolling mill and a 20-roll combination. Cold rolling is performed using a five-stand continuous rolling mill (13) to roll the raw material to the initial thickness. The first three stands of the five-stand continuous rolling mill (13) use cylindrical rolls, while the fourth and fifth stands are designed as tapered rolls with tapered ends. The production process is as follows:

[0102] When the aforementioned thin strip products come off the ESP production line, they are coiled into raw steel coils by the coiling mechanism. The steel coils are then transferred to the cold rolling workshop by a crane to start the subsequent cold rolling process.

[0103] The raw steel coil is first uncoiled by the uncoiling mechanism at the head to obtain raw steel strip;

[0104] As the rolling direction progresses, the raw strip gradually enters the pickling tank 12 for pickling to remove the surface oxide layer;

[0105] After passing through the pickling tank 12, the raw strip steel moves with the conveyor rollers to the area of ​​the five-stand continuous rolling mill 13 to begin cold rolling. Furthermore, in order to prevent excessive reduction from causing the strip steel to tear, the reduction rate between each stand is distributed as follows: the total reduction rate of the five-stand continuous rolling mill 13 does not exceed 83%, and the reduction rate of the cylindrical rolls of the third stand of the five-stand continuous rolling mill 13 is 24%, and the reduction rate of the conical rolls of the fifth stand is 21%. After rolling on the third stand, the thickness of the thin strip is reduced to 0.3±0.05mm, and after rolling on the fifth stand, the thickness of the thin strip is reduced to 0.18±0.01mm.

[0106] The edges of the cold-rolled strip obtained after 13 consecutive rolling on a five-stand continuous rolling mill will crack. It is transported to the edge cutting shearing area by conveyor rollers to remove the edges.

[0107] After the edge scrap is removed, the strip steel is annealed in a continuous annealing furnace and then coiled into cold-rolled steel coils. The annealing temperature is controlled at 880±20℃, and the coils are held at that temperature for 3-5 minutes after annealing. A portion of the cold-rolled steel coils are then used directly as the first-type product, while the other portion is prepared for subsequent warm rolling. These coils are then rolled on a 20-roll mill (23) to become the thinner second-type product. The production speed of the cold-rolled strip steel produced by the above-mentioned five-stand continuous rolling mill (13) should be greater than 850 m / min.

[0108] Another portion of the cold-rolled steel coils enter the warm rolling production line through the uncoiling mechanism. The strip steel is first transported to the magnetic induction heating area by the conveyor, where it is heated to 340°C to obtain preheated steel.

[0109] The preheated steel, heated by magnetic induction heating, enters the area 23 of the 20-roll mill for 5 passes of reciprocating rolling. The reduction rate of the first pass is controlled at 20-22%, the reduction rate of the second pass is controlled at 19-21%, the reduction rate of the third pass is controlled at 13-15%, and the reduction rates of the fourth and fifth passes are both controlled at 10-12%, with the overall reduction rate controlled at 50-53% and the product thickness controlled at 0.09±0.002mm.

[0110] After the third rolling pass is completed, the obtained warm-rolled strip enters the edge trimming area along the rolling direction to remove edge waste and enters the coating area. In the coating area, the silicon steel surface is coated with an insulating coating and then enters the winding mechanism to form a warm-rolled steel coil, which can be used as the second type of product.

[0111] Furthermore, refer to Figure 1 and Figure 2 This application also provides an ultra-thin cold-rolled strip steel production system, employing the aforementioned ultra-thin cold-rolled strip steel production process. The ultra-thin cold-rolled strip steel production system includes:

[0112] A cold rolling production line includes a first uncoiling mechanism 11, a pickling tank 12, a five-stand continuous rolling mill 13, a first edge trimming shear device 14, and a first coiling mechanism 16 arranged in sequence.

[0113] A warm rolling production line is used to perform warm rolling on a portion of the cold-rolled steel coils obtained from the cold rolling production line. The warm rolling production line includes a second uncoiling mechanism 21, a preheating device 22, a 20-roll mill 23, a second edge trimming shear device 24, and a second coiling mechanism 25 arranged in sequence.

[0114] The specific process has been described in detail above and will not be repeated here.

[0115] Optionally, a first continuous annealing furnace 15 is provided between the first trimming shear device 14 and the first winding mechanism 16, and a second continuous annealing furnace is provided between the second trimming shear device 24 and the second winding mechanism 25. The aforementioned preheating device 22 can be, for example, an electromagnetic induction heating device. The twenty-roll mill 23 can be, for example, a 20-roll Sendzimir mill.

[0116] In summary, the production process and system of this application, for producing ultra-thin cold-rolled strip steel (meaning strip steel with a thickness of less than 0.2 mm), has the following advantages:

[0117] (1) A cold rolling production method and system with a simple arrangement that enables ultra-thin strip steel to achieve the required service performance can be provided, which can significantly reduce production costs.

[0118] (2) It can make the five-stand continuous rolling mill 13 and the twenty-roll rolling mill 23 more closely matched with the production process and less likely to cause steel accumulation, thereby reducing production costs and improving production efficiency. At the same time, by setting the diameter of each roll in the five-stand rolling mill, the roll changing cycle of the first stand roll, the second stand roll, the fourth stand roll and the fifth stand roll can be the same, and it is 1.5-2.5 times the roll changing cycle of the third stand roll, which can also reduce costs and save downtime for replacement.

[0119] (3) The system has high applicability and strong versatility in raw material selection. Upstream processes can include Castrip twin-roll thin strip, ESP headless rolling and hot continuous rolling, etc., and can be used for the production of ultra-thin strips of steel grades such as silicon steel and carbon steel.

[0120] (4) Depending on the thickness of the raw material, different passes of the 20-roll mill 23 can be selected for rolling. The strip produced by the five-stand continuous rolling mill 13 can be rolled to the target thickness by the 20-roll mill 23 in 3 or 5 passes to obtain ultra-thin strips of different thicknesses.

[0121] (5) Before the warm rolling process, magnetic induction heating is used to raise the strip to a certain temperature, which effectively prevents the strip from tearing and breaking during multiple rolling processes; multi-pass rolling can also improve the thickness accuracy of the product.

[0122] (6) This application targets raw strip steel with a thickness of 0.7-1mm, and adopts a production method that combines pickling-continuous rolling unit and 20-roll combination of cold rolling and warm rolling. The process is generally divided into cold rolling and warm rolling. The cold rolling process adopts 5-stand continuous rolling, and the warm rolling process adopts 20-roll reversible rolling. The strip steel is rolled to a thickness of 0.15-0.19mm using the five-stand continuous rolling mill 13. It can be directly used as the first type of product, or it can be further processed into the warm rolling process to obtain a second type of product with a thinner thickness. This solves the problems of slow production pace, high cost and low production efficiency in the existing production of high-precision ultra-thin strip steel with a thickness of less than 0.2mm.

[0123] The above are merely illustrative embodiments of the present invention and are not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A production process for ultra-thin cold-rolled strip steel, characterized in that, include: Pickling is performed on raw steel strips with a thickness of 0.7-1.0 mm; Pickled raw strip steel is cold-rolled using a five-stand continuous rolling mill to obtain cold-rolled strip steel; wherein, the diameter of the rolls of the five stands in the five-stand continuous rolling mill is ≤400mm, and the thickness of the cold-rolled strip steel is less than 0.2mm; The cold-rolled strip is subjected to edge trimming and coiling processes in sequence to obtain multiple cold-rolled steel coils. A portion of cold-rolled steel coils will be classified as Category 1 products. Another portion of the cold-rolled steel coils is unwound and then heated to a preset temperature to obtain preheated steel. The preheating strip steel is subjected to warm rolling treatment to obtain warm rolled strip steel; wherein, during the warm rolling treatment, the preheating strip steel is subjected to 3-5 passes of reciprocating rolling using a 20-roll mill; The warm-rolled strip is subjected to edge trimming and coiling processes in sequence to obtain a warm-rolled steel coil, which is a second type of product.

2. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, In the five-stand continuous rolling mill, the diameters of the first stand rolls, second stand rolls, fourth stand rolls, and fifth stand rolls are all larger than the diameter of the third stand roll, and the difference is ≤80mm; the roll changing cycles of the first stand rolls, second stand rolls, fourth stand rolls, and fifth stand rolls are the same, and are 1.5-2.5 times the roll changing cycle of the third stand roll.

3. The production process for ultra-thin cold-rolled strip steel as described in claim 2, characterized in that, In the five-stand continuous rolling mill, the roll diameters of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll are 340-380 mm, and the roll diameter of the third stand roll is 300 mm. The roll changing cycle of the first stand roll, the second stand roll, the fourth stand roll, and the fifth stand roll is twice the roll changing cycle of the third stand roll.

4. The production process of ultra-thin cold-rolled strip steel as described in claim 2, characterized in that, The thickness of the cold-rolled strip is 0.15-0.19 mm.

5. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, In the five-stand continuous rolling mill, the fourth stand roll is a conical work roll; or, in the five-stand continuous rolling mill, both the fourth stand roll and the fifth stand roll are conical work rolls.

6. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The total reduction rate of the five-stand continuous rolling mill shall not exceed 85%. In the five-stand continuous rolling mill, the rolls of the third stand are cylindrical rolls with a reduction rate of 20% to 35%, and the rolls of the fifth stand are conical rolls with a reduction rate of 20% to 28%.

7. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The intermediate annealing process is included between the edge trimming and coiling of the cold-rolled strip steel; the annealing temperature of the intermediate annealing process is 850-950℃, and the holding time after annealing is 3-5 minutes.

8. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The preheating steel is heated by electromagnetic induction, and the preset temperature is 330-370℃.

9. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The thickness of the preheating steel is less than 0.17 mm. During the warm rolling process, the preheating steel is subjected to three reciprocating rolling passes using a 20-roll mill. In the three reciprocating rolling passes, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the overall reduction rate is controlled at 38-46%.

10. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The thickness of the preheating steel is greater than 0.18 mm. During the warm rolling process, the preheating steel is subjected to 5 passes of reciprocating rolling using a 20-roll mill. In the 5 passes of reciprocating rolling, the reduction rate of the first pass is controlled at 20-25%, the reduction rate of the second pass is controlled at 18-22%, the reduction rate of the third pass is controlled at 12-15%, and the reduction rates of the fourth and fifth passes are both controlled at 10-12%, with the overall reduction rate controlled at 50-53%.

11. The production process of ultra-thin cold-rolled strip steel as described in claim 1, characterized in that, The process of trimming and coiling warm-rolled strip steel includes continuous annealing; the annealing temperature of the continuous annealing process is 800-900℃, and the annealing time is 5-8 minutes.

12. A production system for ultra-thin cold-rolled strip steel, characterized in that, The production process for ultra-thin cold-rolled strip steel as described in any one of claims 1-11, wherein the ultra-thin cold-rolled strip steel production system comprises: A cold rolling production line includes a first uncoiling mechanism, a pickling tank, a five-stand continuous rolling mill, a first edge trimming shear, and a first coiling mechanism arranged in sequence. A warm rolling production line is used to perform warm rolling on a portion of the cold-rolled steel coils obtained from the cold rolling production line. The warm rolling production line includes a second uncoiling mechanism, a preheating device, a 20-roll mill, a second edge trimming shear, and a second coiling mechanism arranged in sequence.

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