Thin strip steel continuous casting and rolling unit and strip steel rolling process method thereof

Abstract

The invention discloses a thin strip steel continuous casting and rolling unit and a strip steel rolling process method thereof, and the thin strip steel continuous casting and rolling unit comprises a steel ladle, a tundish, a transition ladle, a casting roller, a first pinch roller, a first rolling mill, a second rolling mill, a plate shape instrument, a cooling device, a second pinch roller, a flying shear, a turning roller and a coiling machine which are sequentially arranged in the rolling direction. A hot box and a loop are arranged between the first rolling mill and the second rolling mill. The thin-strip continuous casting and rolling unit further comprises a controller electrically connected with the strip shape instrument and a thermodetector electrically connected with the controller, and the thermodetector is used for obtaining the temperature of the strip steel at the preset position. The continuous rolling unit capacity of a thin-strip continuous casting and rolling production line can be brought into full play, guarantee is provided for improving the steel product quality, improving the production efficiency, lowering the operation cost and the like, and conditions are provided for development of high-end steel types (such as ultrahigh-strength steel and silicon steel).

Description

Technical Field

[0001] This invention relates to the field of hot-rolled production technology of thin strip steel, and in particular to a continuous casting and rolling mill for thin strip steel and its strip rolling process. Background Technology

[0002] Thin strip continuous casting and rolling technology, also known as thin strip casting and rolling technology, is a near-net-shape thin-gauge hot-rolled strip manufacturing technology. Its industrialization goal is to realize the integration of thin strip continuous casting and rolling, and to achieve stable and mass production.

[0003] There are many types of thin strip continuous casting and rolling technologies. Currently, the most mature industrialized technology is the vertical equal-diameter twin-roll thin strip casting and rolling technology, which can produce thin strip steel with a thickness of less than 1.2mm. The equipment supporting this process mainly includes: ladle, tundish, transition ladle, flow distribution device, casting rolls, hot box, pinch rolls, four-high mill, aerosol cooling device, flying shear, guide rolls, coiler, etc.

[0004] A typical thin strip continuous casting and rolling process involves only one four-high mill in the hot rolling stage, using a single rolling process with a reduction of about 30% (maximum reduction capacity is 50%). The products are mainly carbon steel and high-strength low-alloy steel.

[0005] In the early stages of the development of thin strip casting and rolling technology, a single-stand hot rolling mill configuration was adopted, taking into account factors such as investment and production stability. However, with the gradual breakthroughs in key technologies for stable, high-efficiency thin strip casting and rolling production, the single-stand rolling scheme has encountered production technology bottlenecks, limiting the application and effectiveness of hot continuous rolling equipment and control technology on thin strip casting and rolling production lines.

[0006] Therefore, it is necessary to propose a thin strip continuous casting and rolling mill and its strip rolling process to solve at least one of the above problems.

[0007] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a thin strip continuous casting and rolling mill and its strip rolling process, which fully utilizes the continuous rolling mill capacity of the thin strip continuous casting and rolling production line, providing a guarantee for improving steel product quality, increasing production efficiency and operating costs, and also providing conditions for the development of high-end steel grades (such as ultra-high strength steel and silicon steel).

[0009] The specific technical solution of the embodiments of the present invention is as follows:

[0010] A thin strip steel continuous casting and rolling mill unit includes, arranged sequentially along the rolling direction: a ladle, a tundish, a transition ladle, casting rolls, a No. 1 pinch roll, a No. 1 rolling mill, a No. 2 rolling mill, a shape meter, a cooling device, a No. 2 pinch roll, a flying shear, a guide roll, and a coiler. A hot box and a looper are provided between the No. 1 and No. 2 rolling mills. The ladle, tundish, transition ladle, and casting rolls cooperate to form a cast strip with a first predetermined thickness from the molten steel flowing into the ladle. The No. 1 pinch roll applies traction and tension to the cast strip, conveying it to the No. 1 rolling mill. The No. 1 rolling mill performs a first pass rolling on the cast strip to obtain strip steel. The looper is used for micro-tension control of the strip steel. The hot box is filled with protective gas for heat preservation and oxidation prevention of the strip steel. The No. 2 rolling mill is used for further processing of the strip steel. The strip undergoes a second rolling pass to complete the rolling deformation; the strip shape meter is used to detect and store the quality of the strip after rolling deformation; the cooling device is used to cool the strip after rolling deformation, cooling the strip temperature to a predetermined temperature range; the second pinch roll is used to clamp the cooled strip, apply tension to the strip, and convey the strip to the flying shear; the flying shear is used to dynamically shear the continuously running strip; the steering roll is used to change the conveying direction of the strip, causing the strip to enter the coiling roll gap of the coiler; the coiler is used to coil the strip to form a finished steel coil with a second predetermined thickness; the thin strip continuous casting and rolling mill also includes a controller electrically connected to the strip shape meter, and a temperature measuring instrument electrically connected to the controller, the temperature measuring instrument being used to obtain the temperature of the strip at a predetermined position.

[0011] In a preferred embodiment, the temperature measuring instrument includes: a first temperature measuring instrument disposed between the strip shape measuring instrument and the cooling device, for detecting the temperature of the strip entering the cooling device; and a second temperature measuring instrument disposed between the cooling device and the No. 2 pinch roll, for detecting the temperature of the strip after being cooled by the cooling device.

[0012] In a preferred embodiment, a heat box is also provided between the casting roll and the No. 1 pinch roll, and between the No. 1 pinch roll and the No. 1 rolling mill. The heat box between the casting roll and the No. 1 pinch roll and between the No. 1 pinch roll and the No. 1 rolling mill is filled with protective gas for heat preservation and oxidation prevention of the casting strip.

[0013] In a preferred embodiment, the first predetermined thickness is between 1.4 mm and 2.1 mm; the second predetermined thickness is between 0.5 mm and 1.9 mm.

[0014] In a preferred embodiment, both the No. 1 and No. 2 rolling mills are equipped with work rolls. The thin strip continuous casting and rolling mill unit further includes an online work roll changing device. The online work roll changing device includes: a work roll changing trolley, a work roll push-pull trolley, a work roll bracket, and a roll changing traverse mechanism. The work roll changing trolley is used to carry the work roll push-pull trolley. The work roll push-pull trolley is equipped with a docking mechanism for docking with the work rolls inside the rolling mill. The docking mechanism can automatically dock with or disengage the roll ends of the work rolls. The work roll bracket is used to carry the upper and lower work rolls pulled out of the rolling mill during the roll changing process. The roll changing traverse mechanism is used to traverse the new work roll to the roll changing position and simultaneously traverse the old work roll to the standby position.

[0015] In a preferred embodiment, the docking mechanism includes: an upper hook and a lower hook spaced apart along the height direction of the work roll push-pull trolley, the position of the upper hook corresponding to the upper work roll in the rolling mill, the position of the lower hook corresponding to the lower work roll in the rolling mill, the upper hook being able to automatically hook or detach from the roll end of the upper work roll, and the lower hook being able to automatically hook or detach from the roll end of the lower work roll.

[0016] A strip rolling process based on any of the above-described thin strip continuous casting and rolling mill units, the strip rolling process comprising:

[0017] The molten metal is heated to form molten steel that meets the requirements;

[0018] The molten steel is passed through a ladle, an intermediate ladle, and a transition ladle, and then flows into a casting roll. The casting roll is used to cast the molten steel into a strip with a diameter of 1.4 mm to 2.5 mm.

[0019] The cast strip is conveyed to the No. 1 rolling mill through a hot box filled with protective gas at a predetermined operating speed of less than 120 meters per minute.

[0020] The No. 1 rolling mill is used to perform the first pass rolling of the cast strip to obtain strip steel;

[0021] After the strip is micro-tensioned by a looper, it is transported to the No. 2 rolling mill through a hot box filled with protective gas. The No. 2 rolling mill is used to perform a second rolling pass on the strip to complete the rolling deformation.

[0022] The strip steel after rolling deformation is cooled using a cooling device to reduce the temperature of the strip steel to below 750°C;

[0023] The rolled and deformed strip steel is sheared and coiled to form finished coil steel with a thickness of 0.5 mm to 1.9 mm.

[0024] In a preferred embodiment, the strip rolling process further includes:

[0025] The temperature of the cast strip at the entrance of the No. 1 rolling mill is obtained, and the initial rolling temperature of the cast strip is controlled between 1100°C and 1200°C. The maximum reduction rate of the first pass is controlled at 50%. The temperature of the strip at the exit of the No. 2 rolling mill is obtained, and the temperature of the strip at the exit of the No. 2 rolling mill is controlled between 850°C and 950°C.

[0026] In a preferred embodiment, the maximum reduction rate of the first rolling pass is controlled at 50%, and the maximum total reduction rate of the first rolling pass and the second rolling pass is controlled at 75%.

[0027] In a preferred embodiment, both the No. 1 and No. 2 rolling mills are equipped with work rolls. The thin strip continuous casting and rolling mill unit further includes an online work roll changing device. The online work roll changing device includes: a work roll changing trolley, a work roll push-pull trolley, a work roll bracket, and a roll changing traverse mechanism. The work roll changing trolley is used to carry the work roll push-pull trolley. The work roll push-pull trolley is equipped with a docking mechanism for docking with the work rolls inside the rolling mill. The docking mechanism can automatically dock with or disengage the roll ends of the work rolls. The work roll bracket is used for... The process includes the upper and lower work rolls being pulled out of the rolling mill; the roll-changing traversing mechanism is used to traverse the new work roll to the roll-changing position, and at the same time traverse the old work roll to the standby position; the work roll push-pull trolley has upper and lower hooks spaced apart along the height direction, the position of the upper hook corresponds to the upper work roll in the rolling mill, and the position of the lower hook corresponds to the lower work roll in the rolling mill, the upper hook can automatically hook or detach from the roll end of the upper work roll, and the lower hook can automatically hook or detach from the roll end of the lower work roll; the strip rolling process also includes:

[0028] The work roll changing car, which carries the new work roll, the work roll push-pull car and the work roll bracket, is moved from the grinding roll room to the side of the rolling mill, so that the upper work roll changing track and the lower work roll changing track in the rolling mill are connected with the upper work roll changing track and the lower work roll track next to the rolling mill.

[0029] The work roll push-pull trolley moves to the side of the upper and lower work rolls inside the rolling mill, and the upper hook and the lower hook automatically hook onto the ends of the upper and lower work rolls;

[0030] The work roll push-pull trolley pulls the upper and lower work rolls out of the mill simultaneously along the docking track until the two rolls are completely detached from the mill and supported in the work roll bracket. Then the upper hook and the lower hook are disengaged from the old work roll.

[0031] The roller changing lateral movement mechanism moves the new work roller from the standby position to the roller changing position, while simultaneously moving the old work roller from the roller changing position to the standby position.

[0032] The upper and lower hooks of the work roll push-pull trolley automatically hook onto the roll end of the new work roll, and simultaneously push the new upper and lower work rolls into the roll changing track inside the mill along the docking track.

[0033] After the new work roll is loaded into the rolling mill, the upper hook and the lower hook are automatically disengaged, and the work roll push-pull trolley returns to the work roll changing trolley;

[0034] The work roll changing trolley, carrying the old work roll, the work roll push-pull trolley, and the work roll bracket, returns to the grinding roll space for positioning.

[0035] The technical solution of the present invention has the following significant beneficial effects:

[0036] The thin strip continuous casting and rolling mill provided in this application adopts a double-stand continuous rolling process, which can fully utilize the continuous rolling mill capacity of the thin strip continuous casting and rolling production line. This provides a guarantee for improving steel product quality, increasing production efficiency and reducing operating costs, and also provides conditions for the development of high-end steel grades (such as ultra-high strength steel and silicon steel). Specifically, the No. 1 and No. 2 rolling mills form a double-stand combination. This double-stand collaborative rolling and reasonable distribution of reduction amount result in more advanced process technology. Taking conventional low-carbon steel rolling as an example, by increasing the number of rolling passes, especially by secondary rolling in the recrystallization zone, dynamic recrystallization is used to achieve austenite grain refinement and microstructure homogenization. The overall mechanical properties and surface roughness of the strip are superior to those of a single pass with the same reduction amount. The distribution of reduction amount between the two passes reduces the rolling force of a single pass, reduces the elastic deformation of the rolls, facilitates strip shape control, and improves the dimensional accuracy of the strip. The smaller reduction per pass in a two-stand mill, compared to the larger reduction per pass in a single-stand mill, reduces work roll wear and significantly mitigates the deterioration of strip surface quality caused by increased work roll surface wear and roughness, thus improving strip surface quality. The maximum total reduction rate of 75% across two passes allows for the rolling of thinner strip specifications compared to the 50% maximum reduction rate in a single pass, expanding the product specification range. This wider range of total reduction rates provides rolling process assurance for the development and stable production of new steel grades such as ultra-high-strength steel and silicon steel. Reasonable allocation of reduction per pass ensures even roll wear, reducing roll consumption and contributing to lower production costs.

[0037] Specific embodiments of the invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Within the spirit and scope of the appended claims, embodiments of the invention include many changes, modifications, and equivalents. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description

[0038] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0039] Figure 1 This is a schematic diagram of the structure of a thin strip steel continuous casting and rolling mill provided in the embodiments of this application;

[0040] Figure 2 This is a partial structural schematic diagram of a thin strip steel continuous casting and rolling mill provided in the embodiments of this application;

[0041] Figure 3 This is a schematic diagram of the structure of an online work roll changing device for a thin strip steel continuous casting and rolling mill provided in the embodiments of this application.

[0042] Reference numerals in the figures of this application:

[0043] 1. Steel ladle;

[0044] 2. Intermediate package;

[0045] 3. Transition package;

[0046] 4. Casting rolls;

[0047] 5. Heating box;

[0048] 6. No. 1 pinch roller;

[0049] 7. No. 1 rolling mill;

[0050] 8. Looping;

[0051] 9. Thermometer;

[0052] 10. Cooling device;

[0053] 104. Strip steel;

[0054] Rolling mills No. 11 and No. 2;

[0055] 12. Plate shape meter;

[0056] 13. No. 2 pinch roller;

[0057] 14. Flying shears;

[0058] 15. Steering rollers;

[0059] 16. Winding machine;

[0060] 17. Work roll changing car;

[0061] 18. Work roll push-pull trolley;

[0062] 181. Hook up;

[0063] 182. Lower hook;

[0064] 19. Work roller support;

[0065] 201. Install the upper working roller;

[0066] 202. Lower work roll;

[0067] 20. Roller changing track. Detailed Implementation

[0068] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

[0069] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0071] In related technologies, the process flow of a thin strip casting and rolling production line is as follows: molten steel that has undergone refining is cast into a strip by a twin-roll casting machine. After one thinning rolling process, it is cooled and sheared before being sent to a coiler to be coiled into a coil.

[0072] The inventors of this application have discovered that current thin strip continuous casting and rolling technology is limited by single-stand rolling, and typical solutions have the following shortcomings in terms of product performance, quality, production, and maintenance:

[0073] 1. The single-pass reduction of 30% and the maximum reduction of 50% limit the breakthrough of the lower limit of product thickness.

[0074] 2. Single-pass rolling cannot achieve multi-stage dynamic recrystallization, resulting in insufficient grain refinement and uneven size distribution, which affects mechanical properties and microstructure uniformity.

[0075] 3. The rolling force is concentrated in one rolling pass, which intensifies the elastic deformation of the rolls, causing fluctuations in the transverse thickness of the strip and resulting in unstable product shape and quality.

[0076] 4. There is a lack of opportunity to correct the surface quality of the strip through secondary rolling;

[0077] 5. It is impossible to adjust the reduction distribution and rolling temperature distribution through multi-stand coordination, resulting in limited rolling control methods, which is not conducive to the development of high-end steel grades such as ultra-high strength steel and silicon steel;

[0078] 6. The production of thin strip with high reduction leads to increased roll consumption and frequent roll changes; moreover, it is impossible to realize online roll changing technology during the rolling stage. The downtime for roll changing shortens the production time of headless rolling, affecting production efficiency, process stability and product quality.

[0079] Furthermore, in related technologies, the roughing zone of a traditional long-process conventional hot strip rolling production line typically employs a two-stand rolling process for hot-rolled strip steel. This process involves reversible, multi-pass rolling on two stands, equipped with a vertical rolling mill, producing intermediate hot-rolled strip steel billets, which subsequently undergo a finishing rolling process to form the final product. However, the embodiments described in this application primarily target the near-net-shape, short-process thin strip casting and rolling production line, where thin cast strip is converted into thin strip steel, which is then directly and continuously rolled into the finished product in an irreversible manner.

[0080] This invention provides a thin strip continuous casting and rolling mill and its strip rolling process, which fully utilizes the continuous rolling mill capacity of the thin strip continuous casting and rolling production line, providing a guarantee for improving steel product quality, increasing production efficiency and operating costs, and also providing conditions for the development of high-end steel grades (such as ultra-high strength steel and silicon steel).

[0081] Please refer to the following for comprehensive information. Figures 1 to 2This application specification provides a thin strip steel continuous casting and rolling mill unit, which may include, arranged sequentially along the rolling direction: ladle 1, tundish 2, transition ladle 3, casting roll 4, No. 1 pinch roll 6, No. 1 rolling mill 7, No. 2 rolling mill 11, shape meter 12, cooling device 10, No. 2 pinch roll 13, flying shear 14, guide roll 15, and coiler 16. A hot box 5 and a looper 8 are provided between the No. 1 rolling mill 7 and the No. 2 rolling mill 11; the ladle 1, the tundish 2, the transition ladle 3, the transition ladle 4, the casting roll 5, the casting roll 6, the No. 1 rolling mill 7, the No. 2 rolling mill 11, the casting roll 6, the casting roll 7, the casting roll 8, the casting roll 9, the casting roll 10, the casting roll 11, the casting roll 12, the casting roll 13, the casting roll 14, the casting roll 15, and the coiler 16. The ladle 3 and the casting roll 4 cooperate to form a casting strip with a first predetermined thickness from the molten steel flowing into the ladle 1; the first pinch roll 6 applies traction and tension to the casting strip and conveys it to the first rolling mill 7; the first rolling mill 7 performs the first pass rolling on the casting strip to obtain strip steel 104; the looper 8 performs micro-tension control on the strip steel 104; the hot box 5 is filled with protective gas to keep the strip steel 104 warm and prevent oxidation; the second rolling mill 11 is used to process the... The strip 104 undergoes a second rolling pass to complete the rolling deformation; the shape meter 12 is used to detect and store the quality of the strip 104 after rolling deformation; the cooling device 10 is used to cool the strip 104 after rolling deformation, cooling the temperature of the strip 104 to a predetermined temperature range; the second pinch roll 13 is used to clamp the cooled strip 104, apply tension to the strip 104, and convey the strip 104 to the flying shear 14; the flying shear 14 is used for continuous operation The strip 104 is dynamically sheared; the guide roller 15 is used to change the conveying direction of the strip 104 so that the strip 104 enters the coiling roller gap of the coiler 16; the coiler 16 is used to coil the strip 104 to form a finished steel coil with a second predetermined thickness; the thin strip continuous casting and rolling mill also includes a controller electrically connected to the shape meter 12, and a temperature measuring instrument 9 electrically connected to the controller, the temperature measuring instrument 9 being used to obtain the temperature of the strip 104 at a predetermined position.

[0082] The thin strip continuous casting and rolling mill provided in this application adopts a double-stand continuous rolling process, which can fully utilize the continuous rolling mill capacity of the thin strip continuous casting and rolling production line, providing a guarantee for improving steel product quality, increasing production efficiency and operating costs, and also providing conditions for the development of high-end steel grades (such as ultra-high strength steel and silicon steel).

[0083] Among them, No. 1 rolling mill 7 and No. 2 rolling mill 11 form a double-stand combination. The double-stand collaborative rolling and reasonable distribution of reduction amount result in more advanced process technology. Taking conventional low carbon steel rolling as an example, by increasing the number of rolling passes, especially by secondary rolling in the recrystallization zone, dynamic recrystallization is used to achieve austenite grain refinement and microstructure homogenization. The comprehensive mechanical properties and surface roughness of strip steel 104 are better than those of single pass with the same reduction amount (for example, when rolling 1.8mm cast strip into strip steel 104 with a final thickness of 0.8mm, the single pass reduction rate is 50%, while the two passes have reduction rates of 40% and 25% respectively).

[0084] The two-pass reduction distribution reduces the single-pass rolling force, decreases the elastic deformation of the rolls, facilitates strip shape control, and improves the dimensional accuracy of strip 104.

[0085] The smaller reduction per pass in the dual-stand mill, compared to the larger reduction per pass in the single-stand mill, can reduce the wear of the work rolls and significantly reduce the deterioration of the surface quality of strip 104 caused by the wear and increased roughness of the work roll surface, thus improving the surface quality of strip 104.

[0086] The maximum total reduction rate of two passes is 75%, which is more than the maximum reduction rate of 50% for a single pass, enabling the rolling of thinner strip steel 104 and expanding the product specification range (the thinnest conventional cast and rolled product is 0.7mm, while this solution can reach 0.5mm).

[0087] The expanded range of total reduction ratios provides rolling process assurance for the development and stable production of new steel grades such as ultra-high strength steel and silicon steel.

[0088] Reasonable allocation of the reduction amount in each pass and uniform wear of the rolls can reduce roll consumption and help reduce production costs.

[0089] Furthermore, the No. 1 rolling mill 7 and the No. 2 rolling mill 11 in this application embodiment can also be equipped with an online work roll changing device to realize the technology of changing work rolls online without stopping the machine, which increases the number of continuous castings, the length of endless rolling and the length of stable production, thereby improving the strip output, yield, quality and uniformity per unit time and enhancing the competitiveness of similar products.

[0090] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0091] The thin strip continuous casting and rolling mill unit may include, in sequence along the production outflow direction of the product: ladle 1, tundish 2, transition ladle 3, casting roll 4, pinch roll 1 6, rolling mill 1 7, rolling mill 2 11, shape meter 12, cooling device 10, pinch roll 2 13, flying shear 14, guide roll 15, coiler 16, with a hot box 5 and looper 8 provided between the rolling mill 1 7 and the rolling mill 2 11.

[0092] The unit is arranged sequentially along the rolling direction: ladle 1 → tundish 2 → transition ladle 3 → casting roll 4 → No. 1 and No. 2 rolling mills 11 → coiler 16, forming a continuous production line for direct coiling of molten steel. This eliminates intermediate steps such as billet cooling, reheating, and billet opening in traditional processes. For example, traditional thick slab rolling requires 20+ passes, while this unit directly forms the first predetermined thickness strip through casting roll 4, and then achieves the second predetermined thickness through two hot rolling passes. This effectively shortens the production cycle and significantly improves production efficiency.

[0093] In this embodiment, the core function of ladle 1 is to store the high-temperature molten steel (typically 1500℃-1600℃) produced in the steelmaking process and stably transport the molten steel to the downstream tundish 2. It is the source storage and transportation unit for molten steel entering the continuous casting and rolling process. By setting up ladle 1, the continuity of molten steel supply for the entire unit can be guaranteed, avoiding production interruptions due to molten steel supply interruptions, and supporting a maximum strip running speed of 120m / min. In addition, ladle 1 can be equipped with a heat insulation structure (such as a refractory material lining inside ladle 1), which can reduce the temperature drop during the molten steel transportation process and provide a temperature basis for the stable solidification of the subsequent casting rolls 4.

[0094] In this embodiment, the tundish 2 serves as a buffer and purification unit between the ladle 1 and the transition ladle 3. It receives the molten steel flowing out of the ladle 1 and can be used to achieve steel diversion, stabilize the molten steel flow rate, and remove inclusions (such as oxide slag and non-metallic inclusions) from the molten steel through settling. Overall, by setting up the tundish 2, the fluctuation of molten steel flow during ladle 1 changeover can be eliminated, avoiding uneven distribution of molten steel in the casting roll 4 due to sudden changes in flow, ensuring the uniformity of the cast strip thickness; it can also reduce inclusions in the molten steel, reduce internal defects in the cast strip (such as delamination, inclusion cracks), and improve the internal quality of the strip steel 104.

[0095] In this embodiment, the transition ladle 3 connects the tundish 2 and the casting rolls 4, further precisely adjusting the flow rate, velocity, and distribution pattern of the molten steel. This allows the molten steel to flow into the gap between a pair of relatively rotating casting rolls 4 in a stable laminar flow state, adapting to the rolling rhythm of the casting rolls 4. The casting rolls 4 rotate at high speed during use. By setting the transition ladle 3, the molten steel can be adapted to the casting strip speed, preventing overflow or flow interruption and ensuring continuous strip forming. Furthermore, it optimizes the filling effect of the molten steel in the gap between the casting rolls 4, reducing defects such as scale and pits on the casting strip surface and improving the surface finish of the casting strip.

[0096] In this embodiment, the casting roll 4 can specifically be a pair of water-cooled copper rolls rotating in opposite directions, and is the core equipment in the continuous casting process. After the molten steel enters the roll gap, it is rapidly cooled by the efficient heat conduction of the casting roll 4 and the internal water cooling system, causing the molten steel to solidify into a continuous casting strip of a predetermined thickness (e.g., 1.4 to 2.5 mm) within the roll gap. This casting roll 4 can be used to achieve one-step forming of molten steel into thin casting strip, skipping the heating and rough rolling stages of traditional thick plate casting, significantly shortening the production process and reducing energy consumption. In particular, when the casting roll 4 is a water-cooled copper roll, its rapid cooling capacity (cooling rate can reach 100 to 1000°C / s) can refine the grain of the casting strip, improve the mechanical properties of the 104 strip steel (such as increasing the yield strength), support high-speed casting strip of up to 120 m / min, and significantly improve the unit's production efficiency.

[0097] In this embodiment, a heat box 5 is also provided between the casting roll 4 and the No. 1 pinch roll 6, and between the No. 1 pinch roll 6 and the No. 1 rolling mill 7. The heat box 5 between the casting roll 4 and the No. 1 pinch roll 6, and between the No. 1 pinch roll 6 and the No. 1 rolling mill 7, is filled with protective gas to keep the casting strip warm and prevent oxidation.

[0098] The heat box 5, located between the casting roll 4 and the first pinch roll 6, and between the first pinch roll 6 and the first rolling mill 7, is used to maintain the high temperature of the cast strip output from the casting roll 4. Nitrogen gas is introduced for inert gas protection, serving as a temperature maintenance and anti-oxidation unit during the transition from continuous casting to hot rolling. After the molten steel passes through the casting roll 4 to form the cast strip, the strip can be fed backward through the heat box 5 into the first pinch roll 6, and then from the first pinch roll 6 into the first rolling mill 7. This maintains the rolling temperature of the cast strip (preventing excessive temperature drop after the strip exits the casting roll 4), providing a stable starting rolling temperature for the subsequent first rolling mill 7, reducing rolling force fluctuations caused by temperature drops, and ensuring rolling stability. Furthermore, by using a protective gas, such as nitrogen, in the heat box 5, air is isolated, preventing the cast strip from reacting with oxygen at high temperatures to form iron oxide scale. This prevents iron oxide scale from being pressed into the surface of the strip 104 (causing surface pitting), thus improving the surface quality of the strip 104.

[0099] In this embodiment, the No. 1 pinch roll 6 specifically refers to a pair of active rolls. These active rolls clamp the casting strip, applying stable traction and tension to it, thus accurately and smoothly conveying the casting strip to the No. 1 rolling mill 7. Simultaneously, the conveying speed and deviation of the casting strip are controlled. By setting up the No. 1 pinch roll 6, slackness or swaying of the casting strip after exiting the hot box 5 can be eliminated, preventing deviation when the casting strip enters the rolling mill (leading to increased edge shearing) and ensuring rolling accuracy. Furthermore, the No. 1 pinch roll 6 can also coordinate the casting strip speed with the rolling speed of the No. 1 rolling mill 7, avoiding steel piling (speed mismatch leading to strip 104 accumulation) or steel pulling (excessive tension leading to uneven strip 104 thinning), maintaining production continuity.

[0100] In this embodiment, the No. 1 rolling mill 7 is used to perform the first pass hot rolling on the cast strip output from the first hot box 5. The initial thinning of the cast strip is achieved by applying rolling force through the rolls, while simultaneously refining the grains and eliminating casting defects (such as porosity) within the cast strip. This initial thinning of the cast strip by the No. 1 rolling mill 7 lays the foundation for the final thickness control (e.g., 0.5 to 1.9 mm) of the No. 2 rolling mill 11, reducing the risk of uneven deformation of the strip 104 caused by excessive single-pass reduction; it also improves the metallographic structure of the cast strip (e.g., transforming the casting structure into a rolled structure), enhancing the ductility and toughness of the strip 104 to meet subsequent processing requirements (such as bending and stamping).

[0101] like Figure 2 As shown, in this embodiment, the heat box 5 between the No. 1 rolling mill 7 and the No. 2 rolling mill 11 is mainly used for secondary heat preservation of the strip 104 output from the No. 1 rolling mill 7, maintaining the final rolling temperature of the strip 104, and preventing the strip 104 from experiencing a rapid temperature drop after the first rolling pass (leading to increased hardness and decreased plasticity), which would affect the second rolling pass. By setting up this heat box 5, a stable final rolling temperature can be ensured for the No. 2 rolling mill 11, avoiding a sudden increase in rolling force due to excessively low strip 104 temperature (which may damage the rolls) or strip 104 brittleness (leading to strip breakage); it also ensures a uniform temperature distribution of the strip 104 (reducing the temperature difference between the edge and the center), preventing strip 104 from developing edge waviness, center waviness, and other plate shape defects after the second rolling pass.

[0102] In this embodiment, in the thin strip continuous casting and rolling mill, the looper 8 between mill 1 (7) and mill 2 (11) (near the exit of mill 1) plays a crucial role in balancing the speed difference between the two mills and stabilizing the tension of the strip 104, thus providing a key guarantee for the continuous and stable rolling of the two hot passes. Specifically, the looper 8 includes the following functions: speed buffering, tension control, and process adaptation.

[0103] The looper 8 eliminates the speed difference between the front and rear hot rolling mills, preventing the strip 104 from accumulating or breaking. In continuous casting and rolling, the process requirements of mill 1 (first pass) and mill 2 (second pass) differ, inevitably leading to speed differences. For example, the first hot rolling requires rapid initial thinning of the cast strip (the speed may be slightly faster), while the second hot rolling requires precise control of the final thickness (the speed may be slightly slower); or due to roll wear, reduction rate adjustments, etc., the actual operating speeds of the front and rear mills may not match. The looper 8 can dynamically balance this difference by storing or releasing strip. When the current mill speed is greater than the rear mill speed, the looper 8 temporarily stores the excess strip 104 (the amount of looper 8 increases); when the current mill speed is less than the rear mill speed, the looper 8 releases the stored strip 104 (the amount of looper 8 decreases), preventing the strip 104 from accumulating between the two mills (causing jamming) or being excessively stretched (causing strip breakage), ensuring continuous and uninterrupted production.

[0104] This looper 8 can maintain a micro-tension of 104 on the strip, ensuring rolling accuracy and strip shape quality.

[0105] Thin strip steel 104 is extremely thin (typically on the millimeter scale) and highly sensitive to rolling tension. Tension fluctuations can directly lead to strip shape defects (such as waviness and warping) or dimensional deviations. One of the core functions of looper 8 is to achieve stable micro-tension control. Looper 8 monitors the tension of strip steel 104 in real time through its own tension detection devices (such as load cells and displacement sensors), and adjusts the lifting height or rotation speed of the looper 8 rolls in conjunction with the drive system to maintain the tension of strip steel 104 within a preset micro-tension range (neither too loose, causing strip steel 104 to deviate, nor too large, causing strip steel 104 to stretch and deform). Stable micro-tension ensures that strip steel 104 remains tightly attached to the roll surface when entering No. 2 rolling mill 11, and the roll pressing force can be evenly applied to the entire width of strip steel 104, avoiding localized thinning or thickening due to uneven tension, and directly improving the thickness accuracy and flatness of the finished strip steel 104.

[0106] This looper 8 can provide a buffer time for unit parameter adjustment and fault handling.

[0107] In actual production, the unit needs to adjust process parameters according to the material of strip 104 (such as low carbon steel, stainless steel) and the required thickness of the finished product, or to deal with temporary minor faults. Loop 8 can provide a critical process buffer. When it is necessary to fine-tune the roll speed and reduction rate of No. 2 rolling mill 11, or to briefly clean the roll surface, there is no need to stop the machine. Loop 8 can release the stored strip 104 to provide time for the parameter adjustment of the downstream unit, while the upstream unit can still roll normally, avoiding production interruption and energy waste caused by shutdown. If minor defects appear on the surface of strip 104 and need to be temporarily treated, loop 8 can also adjust the amount of stored strip to slow down the conveying speed of strip 104, buying time for the treatment operation without affecting the overall production rhythm.

[0108] Overall, looper 8 is a key bridge connecting rolling mill 7 of No. 1 and rolling mill 11 of No. 2. Through its three major functions of speed buffering, tension stabilization and process adaptation, it not only solves the core contradiction of speed asynchrony during continuous rolling, but also ensures the rolling accuracy and production continuity of thin strip steel 104. It is an important piece of equipment to ensure the efficient and stable operation of the entire continuous casting and rolling mill unit.

[0109] In this embodiment, the No. 2 rolling mill 11 is mainly used for the second hot rolling of the strip 104 output from the second hot box 5. By precisely controlling the roll reduction, the thickness of the strip 104 is ultimately controlled within the target thickness range (0.5 to 1.9 mm), while further optimizing the shape and mechanical properties of the strip 104. By setting up the No. 2 rolling mill 11, the thickness of the finished strip 104 is precisely controlled to meet the thickness requirements of different downstream applications (such as home appliance panels and lightweight automotive components); it further refines the grains and homogenizes the microstructure, making the strength, hardness and other mechanical properties of the strip 104 more stable and reducing performance fluctuations; and with the feedback from the shape meter 12, the rolling mill parameters (such as roll gap tilt and work roll bending) are adjusted to correct shape defects and improve the shape accuracy of the finished product.

[0110] In this embodiment, the strip shape meter 12 is installed downstream of the No. 2 rolling mill 11. It measures the strip shape parameters (such as waviness, camber, and thickness variation) of the rolled strip 104 in real time using contact (e.g., roller type) or non-contact (e.g., laser) detection methods, and feeds the data back to the rolling mill control system. By setting up this strip shape meter 12, the strip shape quality of the strip 104 can be monitored in real time, defects such as edge waviness, center waviness, and camber can be detected promptly, triggering automatic adjustment of rolling mill parameters (such as adjusting the bending and force of the work rolls), reducing the generation of defective products; accumulating strip shape data allows for optimization of rolling process parameters (such as reduction rate distribution and tension setting), and long-term improvement in strip shape qualification rate (typically exceeding 95%).

[0111] In this embodiment, the cooling device 10 is specifically a precision aerosol cooling device 10, which uses compressed air + water aerosol spraying to rapidly and uniformly cool the high-temperature strip steel 104 after rolling, reducing the temperature of the strip steel 104 from the final rolling temperature to below 750°C. This is a key unit for controlling the microstructure and properties of the strip steel 104. This cooling device 10 has an adjustable aerosol cooling rate, allowing it to adapt to the needs of different steel grades by controlling the cooling speed. For example, by regulating the phase transformation process of the strip steel 104 (such as converting austenite to ferrite + pearlite, or bainite), the hardness, strength, and other mechanical properties of the strip steel 104 can be precisely controlled (e.g., rapid cooling can improve the yield strength of low-carbon steel). Rapid cooling can shorten the residence time of the strip steel 104 in the high-temperature zone, reduce secondary oxidation (avoiding the formation of thick iron oxide scale), and simultaneously inhibit grain growth, ensuring a uniform microstructure of the strip steel 104.

[0112] In this embodiment, the second pinch roller 13 is used to clamp the cooled strip 104, apply stable tension to the strip 104, and smoothly convey the strip 104 to the flying shear 14. Simultaneously, it controls the conveying speed and deviation of the strip 104 to match the shearing rhythm of the flying shear 14. In specific use, the second pinch roller 13 can eliminate thermal deformation (such as slight bending) of the cooled strip 104, ensuring the straightness of the strip 104 when entering the flying shear 14 and preventing excessive length deviation of the strip 104 after shearing. Typically, the length tolerance can be controlled within ±5mm. Furthermore, the second pinch roller 13 can also coordinate the speed of the strip 104 with the shearing speed of the flying shear 14, preventing the flying shear 14 from performing empty shearing or overlapping shearing, ensuring a continuous and stable shearing process.

[0113] In this embodiment, the flying shear 14 is used to dynamically cut the continuously running strip 104 according to the set weight or length of the finished steel coil. In specific use, the flying shear 14 can achieve fixed-length cutting of the strip 104, meeting the customized requirements of downstream users for the length / weight of the steel coil, such as the common 20 tons / coil, 30 tons / coil, etc. Furthermore, the flying shear 14 can also remove transitional defect sections at the beginning and end of the strip 104, such as irregular portions at the head of the cast strip and thin edges at the tail, improving the effective utilization rate of the finished steel coil, typically increasing the utilization rate to over 98%.

[0114] In this embodiment, the guide roller 15 is used to change the conveying direction of the strip 104, such as turning the horizontally conveyed strip 104 into a vertical or inclined conveying direction, so that the strip 104 accurately enters the winding roll gap of the coiler 16, adapting to the spatial layout of the unit. In specific use, the guide roller 15 can optimize the unit layout: it eliminates the need to directly align the coiler 16 with the flying shear 14, saving factory space, especially for high-speed units, which can shorten the total length of the unit by 10% to 15%; in addition, the guide roller 15 can also ensure the smoothness of the strip 104 during turning, avoiding wrinkles and scratches on the strip 104 during the turning process, and protecting the surface quality of the strip 104. Specifically, the surface of the guide roller 15 is usually chrome-plated to reduce the coefficient of friction, thereby better protecting the surface quality of the strip 104.

[0115] In this embodiment, the coiler 16 is used to coil the cut strip steel 104 from the flying shear 14 into a tight steel coil by actively rotating the coiling rollers. Simultaneously, pressure is applied by the auxiliary coiling rollers to ensure the coiling density and roundness, ultimately forming a finished steel coil. In practical use, the coiler 16 enables the compact packaging of the finished strip steel 104, reducing storage and transportation space. Compared to loose strip steel 104, the storage efficiency of the steel coil is increased by 5 to 10 times. During the coiling process, the coiler 16 controls the coiling tension and auxiliary coiling pressure to prevent the steel coil from becoming loose (easily deformed) or too tight (easily generating internal stress), ensuring the stability of the steel coil during subsequent transportation and uncoiling, and reducing finished product loss.

[0116] The guide roller 15 and the coiler 16 can be used together. A single set of guide rollers 15 and coilers 16 can be installed in this thin strip continuous casting and rolling mill, or multiple sets of guide rollers 15 and coilers 16 can be installed, for example... Figure 1 As shown, two sets of guide rollers 15 and winding machines 16 can be set up. Taking the setup of two sets of guide rollers 15 and winding machines 16 as an example, the two winding machines 16 can form a dual-station winding machine 16. After one roll is produced, it can be immediately switched to another winding system for winding without stopping and waiting. In addition, multiple sets of guide rollers and winding machines 16 can support the simultaneous operation of different production modes.

[0117] In this embodiment, the thin strip continuous casting and rolling mill further includes a temperature measuring instrument 9, which is used to obtain the temperature of the strip 104 at a predetermined position. Specifically, the temperature measuring instrument 9 may include: a first temperature measuring instrument 9, which is disposed between the shape measuring instrument 12 and the cooling device 10, for detecting the temperature of the strip 104 entering the cooling device 10; and a second temperature measuring instrument 9, which is disposed between the cooling device 10 and the No. 2 pinch roll 13, for detecting the temperature of the strip 104 after being cooled by the cooling device 10.

[0118] The first temperature measuring instrument 9 can be used to measure the temperature of the thin strip steel 104 in real time before it enters the cooling device 10. Specifically, the temperature measuring instrument 9 can be an infrared temperature measuring instrument 9, which can include an infrared probe. Through the infrared probe, the surface temperature of the strip steel 104 can be quickly and accurately obtained, providing a basis for subsequent production operations. The second temperature measuring instrument 9 is set after the outlet of the cooling device 10, which can verify the cooling effect in real time, forming a closed-loop feedback to avoid subsequent rolling force fluctuations due to insufficient cooling or internal stress caused by over-cooling. This dual-point temperature measurement design can control the temperature fluctuation of the strip steel 104 after cooling within a small temperature fluctuation range, improving the temperature control accuracy. For example, the temperature fluctuation can be controlled within ±5℃, which is significantly better than the temperature control accuracy of traditional single-point temperature measurement.

[0119] In practical use, the temperature data measured by the temperature measuring instrument 9 serves as an important basis for adjusting the cooling device 10. Based on the actual temperature of the strip 104, the control system of the thin strip continuous casting and rolling mill can automatically adjust parameters such as the cooling intensity and cooling time of the cooling device 10 to achieve precise temperature control of the strip 104. For example, when the temperature measuring instrument 9 detects that the temperature of the strip 104 is higher than the set value, the cooling device 10 can increase the cooling water volume to accelerate the cooling rate of the strip 104. Monitoring the temperature of the strip 104 helps determine whether the temperature uniformity of the strip 104 meets the requirements, promptly identifying abnormal temperature areas, thereby avoiding quality problems such as poor strip shape and inconsistent microstructure caused by uneven temperature. For example, if the temperature measuring instrument 9 finds a large difference between the edge temperature and the center temperature of the strip 104, the rolling process or cooling strategy can be adjusted in time to ensure the quality of the strip 104. The temperature measuring instrument 9 can also indirectly protect downstream equipment. If the temperature of strip 104 is too high, it may damage subsequent equipment such as pinch rolls and flying shear 14. By monitoring the temperature of strip 104 in real time, it is possible to prevent strip 104 with excessive temperature from entering subsequent equipment and extend the service life of the equipment.

[0120] The thin strip steel continuous casting and rolling mill provided in this application embodiment achieves continuous, high-speed, and high-quality production from molten steel to finished steel coils through the coordinated operation of various structures. Specifically, the thin strip steel continuous casting and rolling mill has the following features during operation:

[0121] Efficiency and cost advantages: By skipping the heating and rough rolling processes of traditional thick billets, the production process is shortened by more than 50%; the casting speed reaches 120m / min, and the annual output can reach millions of tons. At the same time, the simplified process reduces energy consumption by 30% to 40%.

[0122] High quality stability: Through the whole process of purification in intermediate ladle 2 → nitrogen anti-oxidation → closed-loop control of plate shaper 12 → precise cooling of aerosol, the thickness tolerance (±0.05mm), plate shape accuracy (wavy degree ≤2mm / m), and surface qualification rate (≥98%) of the finished strip steel 104 are all at the high level in the industry, and the mechanical properties fluctuate little.

[0123] High product flexibility: By adjusting the hot rolling reduction rate (the total reduction rate of the two passes is controllable), 104 thin strip steel of various specifications from 0.5 to 1.9 mm can be produced, which can meet the needs of many fields such as home appliances, automobiles, and building materials, and the product has strong adaptability.

[0124] This invention employs a two-pass rolling process in the rolling stage, replacing the previous single-pass rolling process. Two hot rolling mills are correspondingly arranged in series to form a truly continuous rolling process, rationally distributing the reduction load between the two passes. Simultaneously, a hot box 5 and a looper 8 are installed between the two hot rolling mills to ensure the secondary rolling temperature of the strip 104, coordinate the strip speed between stands, and ensure stable tension control. Online roll changing technology is adopted, allowing for the replacement of mill rolls without interrupting the rolling process, solving the downtime problem caused by roll wear, and improving production efficiency and product quality.

[0125] The twin-stand rolling mill achieves true thermomechanical rolling by increasing the number of rolling passes and incorporating a post-rolling cooling device 10. The twin-stand controlled rolling and cooling process further improves the thickness accuracy, surface quality, and thickness specification range of 104 strip steel, and provides users with technological guarantees for the stable production of high-end steel grades such as ultra-high-strength steel and silicon steel.

[0126] like Figure 3 As shown, in one embodiment, both the No. 1 rolling mill 7 and the No. 2 rolling mill 11 are equipped with work rolls. The thin strip continuous casting and rolling mill also includes an online work roll changing device. The online work roll changing device includes: a work roll changing carriage 17, a work roll push-pull carriage 18, a work roll bracket 19, and a roll changing traverse mechanism. The work roll changing carriage 17 is used to carry the work roll push-pull carriage 18. The work roll push-pull carriage 18 is equipped with a docking mechanism for docking with the work rolls in the rolling mill. The docking mechanism can automatically dock with or disengage the roll ends of the work rolls. The work roll bracket 19 is used to carry the upper work roll 201 and the lower work roll 202 that are pulled out of the rolling mill during the roll changing process. The roll changing traverse mechanism is used to traverse the new work roll to the roll changing position and at the same time traverse the old work roll to the standby position.

[0127] Specifically, the docking mechanism includes an upper hook 181 and a lower hook 182 spaced apart along the height direction on the work roll push-pull carriage 18. The position of the upper hook 181 corresponds to the upper work roll 201 in the rolling mill, and the position of the lower hook 182 corresponds to the lower work roll 202 in the rolling mill. The upper hook 181 can automatically hook or detach from the roll end of the upper work roll 201, and the lower hook 182 can automatically hook or detach from the roll end of the lower work roll 202.

[0128] In this embodiment, the online work roll changing device is used to improve roll changing efficiency, ensure production continuity, and enhance operational safety and automation.

[0129] Traditional hot rolling mills require manual disassembly, handling, and installation after shutdown, resulting in long roll change cycles (typically 1-2 hours) and severely impacting continuous production. This online roll changing device, however, achieves highly efficient roll changing through integrated design. Specifically, the roll changing trolley 17 carries a push-pull carriage that can quickly move to the roll changing position on the mill, reducing equipment alignment time. The roll changing traverse mechanism simultaneously completes the bidirectional operation of moving the new roll to the changing position and the old roll to the standby position, avoiding the time wasted on separate steps. Combined with the automatic docking mechanism, manual alignment of the roll ends is eliminated, further reducing operation time. In practical applications, the time for a single roll change can be reduced to a few minutes, significantly increasing production capacity.

[0130] The work rolls of thin strip continuous casting and rolling mills operate in high-temperature (roll surface temperatures can reach 500℃-800℃) and high-pressure environments. Manual roll changing poses safety hazards such as burns and injuries from handling heavy objects, and manual docking has low precision (easily leading to roll system installation deviations and affecting the quality of strip 104). This online work roll changing device, through the setting of a docking mechanism, can automatically complete the docking / disengagement with the work roll end without manual assistance. Specifically, the docking structure can be upper and lower hooks 182, corresponding to the upper and lower work rolls 202. The mechanical structure achieves precise hooking / disengagement, avoiding human judgment errors, and the docking success rate can reach over 99%. This automated design reduces the labor intensity and safety risks of operators, and also reduces equipment damage (such as roll end collisions) or product quality fluctuations caused by improper manual operation.

[0131] The precision requirements for work rolls (especially those used for rolling thin strip 104) are extremely high (roll surface roughness and roundness errors must be controlled within the micrometer level). Instability during roll changing can easily lead to deformation of the roll system or surface scratches, directly affecting the shape and surface quality of the subsequently rolled strip 104. The work roll bracket 19 stably supports the pulled-out old roll during roll changing, preventing deformation and scratches caused by roll swaying or falling. The upper and lower hooks 182 are precisely aligned with the upper and lower work rolls 202, with uniform hooking force, preventing axial movement or radial displacement of the work rolls during roll changing, ensuring that the roll system maintains its original precision after installation. This stability design can control the loss of roll system precision caused by roll changing to within 0.01mm, ensuring the thickness tolerance (±0.02mm) and shape requirements of the subsequently rolled strip 104.

[0132] The core advantage of continuous casting and rolling of thin strip steel 104 is continuous and high-efficiency production. The long downtime of traditional roll changing will disrupt this balance (for example, the downtime will cause the temperature of the cast strip to drop, which requires reheating, increases energy consumption and affects the microstructure of strip steel 104).

[0133] The online roll changing device can complete roll changing with a short-term speed reduction rather than a complete shutdown of the unit. Combined with the strip storage function of looper 8, the strip 104 can still be continuously conveyed during the roll changing process, avoiding production interruptions, temperature fluctuations, or scrapping of strip 104 due to shutdown. This adaptability ensures the continuity of the entire process from continuous casting and rolling molten steel to finished coil, further amplifying its energy-saving and high-efficiency advantages in a short process.

[0134] This online work roll changing device solves the pain points of traditional roll changing, such as long time, high risk and poor accuracy, through its structure design of automated docking, synchronous lateral movement and stable load bearing. It can not only ensure the efficiency and safety of work roll changing, but also adapt to the continuous production needs of 104 thin strip steel continuous casting and rolling. Ultimately, it can achieve the production goals of high operating rate, high quality and low loss. It is a key technology upgrade to improve the overall performance of the unit.

[0135] The thin strip continuous casting and rolling mill provided in this application embodiment, during use, flows into a pair of relatively rotating water-cooled copper casting rolls 4 through the ladle 1, intermediate ladle, and transition ladle 3 to form a casting strip with a thickness of 1.4 to 2.5 mm. The maximum running speed of the casting strip is 120 m / min. After passing through a hot box 5 protected by nitrogen, the casting strip undergoes two or one hot rolling passes. The rolled strip 104 is cooled by air mist to a temperature below 750°C. The cooled strip 104 is then sheared and coiled to form finished steel coils with a thickness of 0.5 to 1.9 mm.

[0136] Unlike the typical thin strip continuous casting and rolling process, this invention adopts a double-stand continuous rolling method in the rolling stage, and sets up a hot box 5 and a looper 8 between the two hot rolling mills. Both rolling mills are equipped with online work roll changing devices, which can realize a production mode of changing rolls without stopping the machine.

[0137] Meanwhile, this technical solution applies continuous rolling technology to thin strip casting and rolling mills, especially the hot rolling process. Based on the steel grade and the content of alloy elements, the rolling temperature window for each pass is matched, especially the final rolling temperature of the second pass is controlled.

[0138] To fully illustrate the production process of the thin strip continuous casting and rolling mill, based on the thin strip continuous casting and rolling mill provided in the above embodiments, this application also provides a strip rolling process method for the thin strip continuous casting and rolling mill, the strip rolling process method including:

[0139] Step S11: Heating the molten metal to form molten steel that meets the requirements;

[0140] Step S12: The molten steel formed is passed through ladle 1, tundish 2, and transition ladle 3 and flows into casting roll 4. The casting roll 4 is used to cast the molten steel into a casting strip with a diameter of 1.4 mm to 2.5 mm.

[0141] Step S13: The cast strip is conveyed to the No. 1 rolling mill 7 through the hot box 5 filled with protective gas at a predetermined operating speed of less than 120 meters per minute;

[0142] Step S14: Use the No. 1 rolling mill 7 to perform the first pass rolling on the cast strip to obtain strip steel 104;

[0143] Step S15: After the strip is micro-tensioned by the looper 8, the strip 104 is transported to the No. 2 rolling mill 11 through the hot box 5 filled with protective gas. The No. 2 rolling mill 11 is used to perform a second rolling on the strip 104 to complete the rolling deformation.

[0144] Step S16: Cool the strip 104 after rolling deformation using the cooling device 10 to reduce the temperature of the strip 104 to below 750°C.

[0145] Step S17: The rolled strip 104 is cut and coiled to form finished coils with a thickness of 0.5 mm to 1.9 mm.

[0146] In this embodiment, during the rolling of strip 104, the molten metal undergoes processes such as converter steelmaking, VD furnace vacuum degassing, and LF refining and heating to form molten steel that meets the requirements. This molten metal then flows through ladle 1, tundish 2, and transition ladle 3 into a pair of relatively rotating casting rolls 4, forming a cast strip with a thickness of 1.4mm to 2.5mm. The maximum running speed of the cast strip is 120m / min. When the thickness of the cast strip is between 1.4mm and 2.5mm, it avoids both insufficient deformation and poor grain refinement during the first rolling pass due to excessive thinness (e.g., <1.4mm) and excessive thickness (e.g., >2.5mm), which would increase the reduction load in the subsequent two rolling passes (potentially leading to accelerated roll wear or strip 104 breakage). This thickness range ensures that the total reduction rate of the subsequent two rolling passes is controlled within a reasonable range (e.g., a total reduction rate within 75%), resulting in a final product thickness that is stable between 0.5mm and 1.9mm, meeting the requirements of various specifications such as automotive steel sheets and appliance steel sheets.

[0147] Furthermore, the strip rolling process method further includes: obtaining the temperature of the cast strip at the entrance of the No. 1 rolling mill 7, controlling the initial rolling temperature of the cast strip to be between 1100°C and 1200°C, controlling the maximum reduction rate of the first pass to be 50%, obtaining the temperature of the strip 104 at the exit of the No. 2 rolling mill 11, and controlling the temperature of the strip 104 at the exit of the No. 2 rolling mill 11 to be between 850°C and 950°C.

[0148] The maximum reduction rate of the first rolling pass is controlled at 50%, and the maximum total reduction rate of the first and second rolling passes is controlled at 75%.

[0149] The strip rolling process provided in this application enables high-quality, high-efficiency, and low-energy-consumption rolling of thin-gauge strip 104. It can precisely control the thickness and specifications of strip 104, stably produce thin-gauge finished products, optimize the microstructure and surface quality of strip 104, and improve the mechanical properties of the product; match the short process of continuous casting and rolling, improve production efficiency and continuity; reduce energy consumption and costs, and achieve green and efficient production.

[0150] Specifically, molten steel is directly cast into a 1.4-2.5mm strip using casting roll 4. Compared to traditional continuous casting (where the billet thickness is typically 100-200mm), this significantly reduces deformation during subsequent rolling and avoids the accumulation of thickness deviations caused by multiple rolling processes. The first rolling pass (rolling mill 7) is combined with the second rolling pass (rolling mill 11). Specifically, the maximum reduction rate in the first pass is 50%, and the total maximum reduction rate is 75%. A gradual rolling process of first roughing to thin the strip and then finishing to fix the thickness is adopted to avoid the strip breaking or shape defects (such as waviness) caused by excessive reduction rate in a single pass. Finally, a stable thin-gauge finished product of 0.5-1.9mm is produced, with a thickness tolerance that can be controlled within ±0.02mm, meeting the high-precision requirements of automotive steel sheets, home appliance sheets, etc.

[0151] This strip rolling process allows for temperature control to adapt to phase transformation requirements: by controlling the first hot rolling inlet temperature at 1100℃-1200℃ and the second hot rolling outlet temperature at 850-950℃, the 1100-1200℃ range represents the austenitic region of the steel, where its plasticity is optimal, reducing roll load and minimizing rolling cracks. The 850-950℃ range provides space for subsequent cooling (below 750℃), ensuring that strip 104 forms a uniform ferrite + pearlite structure during cooling, improving tensile strength (by 10%-15%) and elongation (by 5%-8%). Furthermore, the cast strip is transported through a hot box 5 filled with protective gas, preventing the high-temperature cast strip from contacting air and generating iron oxide scale (the oxidation loss rate in traditional processes is 2%-3%, which can be reduced to below 0.5%), ensuring that the surface roughness Ra of strip 104 is ≤1.6μm, allowing it to be directly used for cold rolling or surface treatment without subsequent pickling.

[0152] Furthermore, the maximum total reduction rate of the first and second rolling passes is 75%, which can refine the grain size of the steel through rolling deformation (the grain size can be refined from 50μm in the traditional process to below 20μm), thereby further enhancing the hardness and toughness of the strip steel 104 and meeting the application scenarios of high-strength thin strip steel 104.

[0153] The process parameters designed in this application are fully compatible with the short-process unit of molten steel → strip casting → hot rolling → coiling, which can maximize the advantages of continuous production. Specifically, speed and equipment are coordinated to prevent interruptions: the predetermined operating speed is controlled within 120 meters / minute, which avoids incomplete strip casting (such as steel leakage, uneven thickness) caused by excessive speed, and can match the micro-tension control of looper 8. When the speed of the hot rolling mill fluctuates, looper 8 can buffer through strip storage / release to ensure continuous conveying of strip 104 and avoid downtime caused by speed mismatch. The short process can reduce intermediate links. Specifically, after the molten steel is directly cast into strip, there is no need for cooling and reheating. Combined with two-pass rolling + online roll changing, the single production cycle is shortened from 2-3 hours in the traditional process to 30-60 minutes, and the hourly capacity of the unit is increased by 200%-300%, which is suitable for large-scale batch production.

[0154] The parameters in this strip rolling process are deeply integrated with the thin strip continuous casting and rolling mill. Through precise setting of strip thickness, rolling speed, temperature, and reduction rate, it not only adapts to the short-process characteristics of the thin strip continuous casting and rolling mill, but also solves the industry pain points of difficult precision control, unstable quality, and high energy consumption of thin strip 104. Ultimately, it achieves the triple goal of high-quality thin strip 104 + efficient continuous production + low energy consumption cost, which is especially suitable for fields such as automobiles and home appliances that have high requirements for the precision and performance of thin strip 104.

[0155] In one embodiment, both the No. 1 rolling mill 7 and the No. 2 rolling mill 11 are equipped with work rolls. The thin strip continuous casting and rolling mill unit also includes an online work roll changing device. The online work roll changing device includes: a work roll changing carriage 17, a work roll push-pull carriage 18, a work roll bracket 19, and a roll changing traverse mechanism. The work roll changing carriage 17 is used to carry the work roll push-pull carriage 18. The work roll push-pull carriage 18 is equipped with a docking mechanism for docking with the work rolls inside the mill. The docking mechanism can automatically dock with or disengage the roll ends of the work rolls. The work roll bracket 19 is used to support the rolls being changed during the roll changing process. Pull out the upper work roll 201 and lower work roll 202 of the rolling mill; the roll changing lateral movement mechanism is used to move the new work roll laterally to the roll changing position, and at the same time move the old work roll laterally to the standby position; the work roll push-pull trolley 18 is provided with upper hook 181 and lower hook 182 at intervals along the height direction, the position of the upper hook 181 corresponds to the upper work roll 201 in the rolling mill, and the position of the lower hook 182 corresponds to the lower work roll 202 in the rolling mill. The upper hook 181 can automatically hook or unhook the roll end of the upper work roll 201, and the lower hook 182 can automatically hook or unhook the roll end of the lower work roll 202;

[0156] The strip rolling process also includes:

[0157] Step S21: The work roll changing car 17, carrying the new work roll, the work roll push-pull car 18 and the work roll bracket 19, is moved from the grinding roll room to the side of the rolling mill, so that the upper work roll 201 changing track 20 and the lower work roll 202 changing track 20 in the rolling mill are connected with the upper work roll 201 changing roller table and the lower work roll 202 track next to the rolling mill.

[0158] Step S22: The work roll push-pull trolley 18 moves to one side of the upper work roll 201 and lower work roll 202 inside the rolling mill, and the upper hook 181 and the lower hook 182 automatically hook onto the ends of the upper work roll 201 and the lower work roll 202.

[0159] Step S23: The work roll push-pull trolley 18 pulls the upper work roll 201 and the lower work roll 202 out of the mill along the docking track until the two rolls are completely detached from the mill and carried in the work roll bracket 19. Then the upper hook 181 and the lower hook 182 are disengaged from the old work roll.

[0160] Step S24: The roller changing lateral movement mechanism is activated, moving the new work roller from the standby position to the roller changing position, while simultaneously moving the old work roller from the roller changing position to the standby position;

[0161] Step S25: The upper hook 181 and lower hook 182 of the work roll push-pull trolley 18 automatically hook the end of the new work roll, and simultaneously push the new upper work roll 201 and lower work roll 202 into the roll changing track 20 in the rolling mill along the docking track.

[0162] Step S26: After the new work roll is loaded into the rolling mill, the upper hook 181 and the lower hook 182 automatically disengage, and the work roll push-pull trolley 18 returns to the work roll changing trolley 17.

[0163] Step S27: The work roll changing trolley 17, carrying the old work roll, the work roll push-pull trolley 18, and the work roll bracket 19, returns to the grinding roll space and is positioned.

[0164] The strip rolling process also includes an online roll changing method for work rolls, which enables fully automated, high-efficiency, high-precision, and low-risk work roll replacement in thin strip continuous casting and rolling mills.

[0165] By utilizing an online work roll changing device to automate the entire roll changing process, manual intervention is completely reduced, and operational risks and errors are minimized. This process designs each step of the roll changing process (transfer, docking, hooking, pushing and pulling, lateral movement, and return) to be automatically executed mechanically, completely replacing traditional manual operation. This fully automated design avoids the risk of burns to operators from high-temperature work rolls (the temperature still reaches 500-800℃ during roll changing) and eliminates random errors in manual operation (such as insufficient roll system installation accuracy caused by docking deviation). The roll changing success rate can be increased to over 99.5%.

[0166] For rolling mills equipped with upper work rolls 201 and lower work rolls 202, synchronized operation significantly shortens roll change time and improves unit operating rate. Specifically, the upper and lower rolls are pushed and pulled synchronously. The work roll push-pull trolley 18 can simultaneously pull out the old upper / lower work rolls 202 and push in the new upper / lower work rolls 202, avoiding the traditional step-by-step operation of changing the upper roll first and then the lower roll, reducing push-pull time by more than 50%. The old and new rolls are transferred synchronously. The roll changing traverse mechanism moves the new roll to the roll changing position and the old roll to the standby position simultaneously, eliminating the need to remove the old roll first and then send the new roll, saving intermediate waiting time. The roll changing trolley operates in an integrated manner, directly transferring the new roll from the rolling mill and carrying the old roll back, eliminating the need for additional equipment for transport and reducing intermediate steps. Combined with these synchronized designs, the time for a single roll change can be reduced to a few minutes (compared to 1-2 hours for traditional manual roll changes), significantly increasing the unit's effective production time (operating rate) and directly increasing the production capacity of thin strip steel 104.

[0167] The rolling of thin strip steel 104 requires extremely high precision of the work rolls (roll surface roundness and roughness error must be ≤0.01mm). Even slight bumps or misalignments during roll changing can lead to a loss of roll system precision, thus affecting the strip shape and surface quality of 104. This process ensures precision through precise control at multiple stages. First, the roll changing track 20 inside the mill is precisely aligned with the roller table beside the mill, preventing misalignment that could cause the rolls to jam or scratch during pushing and pulling. After the old roll is pulled out, it is fully supported within the work roll bracket 19, preventing roll surface deformation or bumps caused by roll swaying or falling during the roll changing process. The upper / lower hooks 182 correspond one-to-one with the upper / lower work rolls 202, with uniform hook force, ensuring that the axis of the new roll is perfectly aligned with the center line of the mill when it is pushed in, avoiding uneven rolling pressure caused by roll system skew (which can easily produce strip waviness). This precision allows the installation accuracy error of the work roll after roll change to be controlled within 0.005mm, ensuring the thickness tolerance (±0.02mm) and flatness of the strip steel in subsequent rolling.

[0168] The core advantage of continuous casting and rolling of thin strip steel is the continuous production from molten steel to finished coils. Prolonged downtime at any stage will disrupt this balance (e.g., downtime causes a drop in strip temperature, requiring reheating to meet rolling temperature requirements and increasing energy consumption). However, by shortening the roll change time (a few minutes), the unit can achieve short-term speed reduction for roll change instead of a complete shutdown. Combined with the strip storage function of looper 8 mentioned earlier, strip 104 can continue to be conveyed during roll change, avoiding production interruptions due to downtime. The roll change process requires no manual intervention, eliminating the need to extend downtime for waiting for manual operation, further reducing strip 104 temperature fluctuations (the temperature drop during roll change can be controlled within 50℃), and avoiding energy losses from subsequent reheating (saving 80-120 kg of standard coal per ton of steel).

[0169] Overall, this online roll changing process, through its three major designs of synchronized operation, precise positioning, and closed-loop management, not only solves the pain points of traditional roll changing, such as heavy reliance on manual labor, long time, poor accuracy, and high risk, but also perfectly adapts to the continuous and high-efficiency production requirements of thin strip steel continuous casting and rolling. Ultimately, it achieves multiple goals of high-efficiency roll changing, automated operation, precise roll system, and continuous production, providing key process guarantees for the unit to stably produce high-quality thin strip steel.

[0170] Specifically, both the first and second hot rolling mills have online work roll changing capabilities. Each mill's online work roll changing device includes one work roll changing trolley 17, one work roll push-pull trolley 18 with two hooks, one set of work roll supports 19, and a conventional roll changing traverse mechanism. The online work roll changing process is as follows:

[0171] A work roll changing trolley 17, carrying a new roll, a work roll push-pull trolley 18, and a work roll bracket 19, moves from the grinding roll area to the side of the mill. The inner working roll 20 and the outer working roll 202 changing tracks are then connected. The work roll push-pull trolley 18 moves to one side of the rolls. The upper and lower hooks of the push-pull trolley automatically hook onto the ends of the inner working rolls 202. The upper and lower working rolls are simultaneously pulled out by the push-pull trolley until they are completely detached from the mill. Located inside the work roll bracket 19 → the upper and lower hooks 182 of the push-pull trolley disengage → the roll changing lateral movement mechanism moves the new roll laterally to the roll changing position, while simultaneously moving the old roll laterally to the standby position → the push-pull trolley automatically hooks the new roll with the hook → the push-pull trolley simultaneously pushes the upper and lower new rolls into the roll changing track 20 inside the mill → the new roll is automatically disengaged after being loaded into the mill → the work roll push-pull trolley 18 returns to its position → the work roll changing trolley 17 loads the old roll, the work roll push-pull trolley 18, and the work roll bracket 19 back into the grinding roll space.

[0172] Unlike typical roll changing methods (where the upper work roll 201 rests on the lower work roll 202 and is pulled out together with it via a hook on the lower work roll 202), this invention adds a work roll bracket 19 and equips the work roll push-pull carriage 18 with two hooks, allowing the upper and lower work rolls 202 to be pulled out simultaneously on their respective tracks. This ensures that the roll body does not contact the running strip 104 and does not interrupt the rolling process. After the new work roll is pushed into the stand, data feedback is obtained through a thickness gauge to calibrate the new roll.

[0173] The dual-stand hot rolling mill unit, consisting of No. 1 mill 7 and No. 2 mill 11, can achieve multiple operating modes: Conventional production mode: Based on the 104mm strip thickness specification, the reduction ratio of the two mills is rationally set, allowing them to work simultaneously or with one mill idle (reduction ratio of 0% to 50% for a single mill, and no more than 75% for both mills); Online roll changing mode: When a single mill has been operating continuously for several hours, or when the rolling volume reaches a set tonnage requiring roll replacement, the online roll changing mode is activated. Through coordinated control of process parameters such as rolling speed of each pass, tension between stands, and reduction ratio distribution of each stand, the rolls of the mill requiring roll replacement gradually open and detach from the 104mm strip surface; after the roll requiring replacement stops rotating, the drive shaft is disengaged, and then the online roll changing operation is performed; after the roll change is completed, the two-mill operation mode is gradually restored; the other mill also uses this operation when it meets the roll changing conditions. In addition, both rolling mills are equipped with automatic thickness control systems to control the bending and shifting of the rolls, as well as segmented roll cooling and rolling lubrication systems.

[0174] It should be noted that in the description of this application, the terms "first," "second," etc., are used only for descriptive purposes and to distinguish similar objects; there is no order between them, nor should they be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0175] The various embodiments described in this specification are presented in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0176] The above are merely a few embodiments of the present invention. Although the embodiments disclosed in the present invention are as described above, the content is only for the purpose of facilitating understanding of the present invention and is not intended to limit the present invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in the form and details of the embodiments without departing from the spirit and scope disclosed in the present invention. However, the patent protection scope of the present invention shall still be determined by the scope defined in the appended claims.

Claims

1. A thin strip steel continuous casting and rolling mill, characterized in that, The thin strip steel continuous casting and rolling unit comprises, sequentially arranged along a rolling direction: a ladle, a tundish, a transition ladle, a casting roll, a first pinch roll, a first rolling mill, a second rolling mill, a flatness meter, a cooling device, a second pinch roll, a flying shear, a reversing roll and a coiler, wherein a hot box and a loop are arranged between the first rolling mill and the second rolling mill. The ladle, the tundish, the transition ladle and the casting roll cooperate to form a cast strip with a first predetermined thickness from molten steel flowing into the ladle. The first pinch roll is used to apply a traction force and a tension to the cast strip to deliver the cast strip to the first rolling mill. The first rolling mill is used to perform first-pass rolling on the cast strip to obtain a strip. The loop is used to perform micro-tension control on the strip. The hot box is filled with a protective gas to perform heat preservation and oxidation prevention on the strip. The second rolling mill is used to perform second-pass rolling on the strip to complete rolling deformation. The flatness meter is used to detect and store the quality of the strip after completing rolling deformation. The cooling device is used to cool the strip after completing rolling deformation to a predetermined temperature range. The second pinch roll is used to clamp the cooled strip, apply a tension to the strip and deliver the strip to the flying shear. The flying shear is used to dynamically shear the continuously running strip. The reversing roll is used to change the delivery direction of the strip to make the strip enter a coiling roll gap of the coiler. The coiler is used to coil the strip to form a finished steel coil with a second predetermined thickness. The thin strip continuous casting and rolling unit further comprises a controller electrically connected to the flatness meter and a temperature measuring instrument electrically connected to the controller, wherein the temperature measuring instrument is used to obtain the temperature of the strip at a predetermined position.

2. The thin strip steel continuous caster and continuous rolling train of claim 1, wherein, The temperature measuring instrument comprises: a first temperature measuring instrument arranged between the flatness meter and the cooling device and used to detect the temperature of the strip entering the cooling device; a second temperature measuring instrument arranged between the cooling device and the second pinch roll and used to detect the temperature of the strip after being cooled by the cooling device.

3. The thin strip steel continuous caster and continuous rolling mill set according to claim 1, characterized by, Hot boxes are also arranged between the casting roll and the first pinch roll and between the first pinch roll and the first rolling mill, wherein the hot boxes are filled with a protective gas to perform heat preservation and oxidation prevention on the cast strip.

4. The thin strip steel continuous caster and continuous rolling mill set as claimed in claim 1, characterized by, The first predetermined thickness is between 1.4 mm and 2.1 mm, and the second predetermined thickness is between 0.5 mm and 1.9 mm.

5. The thin strip continuous caster and rolling mill set according to claim 1, wherein Both the first rolling mill and the second rolling mill are provided with working rolls, and the thin strip continuous casting and rolling unit further comprises an online working roll changing device, wherein the online working roll changing device comprises a working roll changing trolley, a working roll push-pull trolley, a working roll bracket and a roll changing transverse moving mechanism. The working roll changing trolley is used to carry the working roll push-pull trolley. The working roll push-pull trolley is provided with a butt joint mechanism used to butt joint with the working rolls in the rolling mill, and the butt joint mechanism can automatically butt joint or disengage the roll ends of the working rolls. The work roll bracket is used for carrying the upper work roll and the lower work roll pulled out of the rolling mill during the roll changing process; The roll changing transverse moving mechanism is used for moving the new work roll to the roll changing position and moving the old work roll to the standby position.

6. The thin strip steel continuous caster and continuous rolling mill set according to claim 5, characterized by, The docking mechanism comprises upper hooks and lower hooks of the work roll push-pull trolley arranged at intervals in the height direction, the positions of the upper hooks correspond to the upper work rolls in the rolling mill, the positions of the lower hooks correspond to the lower work rolls in the rolling mill, the upper hooks can automatically hook or unhook the roll ends of the upper work rolls, and the lower hooks can automatically hook or unhook the roll ends of the lower work rolls.

7. A strip rolling process method based on the thin strip continuous casting and rolling train according to any one of claims 1 to 6, characterized in that, The strip rolling process comprises: The molten metal is heated to form molten steel meeting the requirements; The formed molten steel is poured into a casting roll through a ladle, a tundish and a transition ladle, and the molten steel is cast to form a cast strip with a thickness of 1.4-2.5 mm by using the casting roll; The cast strip is sent to a No.1 rolling mill at a predetermined running speed within 120 m / min through a hot box filled with protective gas; The No.1 rolling mill is used to perform first-pass rolling on the cast strip to obtain a strip steel; After the cast strip is adjusted by a loop for micro-tension, the strip steel is sent to a No.2 rolling mill through a hot box filled with protective gas, and the No.2 rolling mill is used to perform second-pass rolling on the strip steel to complete rolling deformation; The cooled strip steel is cooled by a cooling device to reduce the temperature of the strip steel to below 750℃; The rolled strip steel is sheared and coiled to form a finished coil steel with a thickness of 0.5-1.9 mm.

8. The strip rolling process method of a thin strip continuous casting and rolling mill set according to claim 7, characterized in that, The strip rolling process further comprises: The temperature of the cast strip at the entrance of the No.1 rolling mill is obtained, the opening rolling temperature of the cast strip is controlled to be 1100-1200℃, the maximum reduction rate of the first pass is controlled to be 50%, the temperature of the strip steel at the exit of the No.2 rolling mill is obtained, and the temperature of the strip steel at the exit of the No.2 rolling mill is controlled to be 850-950℃.

9. The strip rolling process method of a thin strip continuous casting and rolling mill set according to claim 8, characterized in that, The maximum reduction rate of the first-pass rolling is controlled to be 50%, and the maximum total reduction rate of the first-pass rolling and the second-pass rolling is controlled to be 75%.

10. The strip rolling process method of a thin strip continuous casting and rolling mill set according to claim 7, characterized in that, The No. 1 rolling mill and the No. 2 rolling mill are each provided with a work roll, and the thin strip steel continuous casting and rolling unit further comprises an on-line work roll changing device, which comprises a work roll changing trolley, a work roll push-pull trolley, a work roll bracket and a roll changing transverse moving mechanism, the work roll changing trolley is used for carrying the work roll push-pull trolley, the work roll push-pull trolley is provided with a butt joint mechanism for butt jointing with the work roll in the rolling mill, the butt joint mechanism can automatically butt joint or disengage the roll end of the work roll, the work roll bracket is used for carrying the upper work roll and the lower work roll pulled out of the rolling mill during roll changing, and the roll changing transverse moving mechanism is used for moving the new work roll to a roll changing position and moving the old work roll to a standby position, the work roll push-pull trolley is provided with upper hooks and lower hooks which are spaced apart along the height direction, the position of the upper hooks corresponds to the upper work roll in the rolling mill, the position of the lower hooks corresponds to the lower work roll in the rolling mill, the upper hooks can automatically hook or disengage the roll end of the upper work roll, and the lower hooks can automatically hook or disengage the roll end of the lower work roll, and the strip steel rolling process further comprises the following steps: moving the work roll changing trolley carrying the new work roll, the work roll push-pull trolley and the work roll bracket from the roll grinding room to the position beside the rolling mill, so that the upper work roll changing track and the lower work roll changing track in the rolling mill are butt jointed with the upper work roll changing track and the lower work roll track beside the rolling mill; moving the work roll push-pull trolley to one side of the upper work roll and the lower work roll in the rolling mill, and the upper hooks and the lower hooks automatically hook the roll ends of the upper work roll and the lower work roll; pulling out the upper work roll and the lower work roll in the rolling mill along the butt joint track by the work roll push-pull trolley, until the two work rolls are completely separated from the rolling mill and are carried in the work roll bracket, and then the upper hooks and the lower hooks are disengaged from the old work rolls; moving the new work roll from the standby position to the roll changing position and moving the old work roll from the roll changing position to the standby position by the roll changing transverse moving mechanism; hooking the roll ends of the new upper work roll and the new lower work roll by the upper hooks and the lower hooks of the work roll push-pull trolley, and pushing the new upper work roll and the new lower work roll into the roll changing track in the rolling mill along the butt joint track; after the new work rolls are loaded into the rolling mill, the upper hooks and the lower hooks are automatically disengaged, and the work roll push-pull trolley returns to the work roll changing trolley; returning the work roll changing trolley carrying the old work rolls, the work roll push-pull trolley and the work roll bracket to the roll grinding room.

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