Small single heavy, thin specifications of special steel steel plate continuous multi-fire rolling production process and equipment

Abstract

The present application belongs to the rolling processing technical field of special steel medium plate, and discloses a small single weight, thin specification special steel plate continuous multi-fire rolling production process and equipment. The design concept of "core equipment seamless connection + closed loop integrated control" is adopted to seamlessly connect the plate blank step-by-step heating furnace, four-roll reversible hot rolling mill, vertical lifting type heating furnace (exclusive temperature compensation purpose), hot straightening machine, fixed-length shearing machine set and plate stacking collecting machine set and other core process equipment, and through seamless connection and integrated integration of the special conveying roller, a full-process closed loop continuous rolling production line is formed. The production line can realize online multi-fire continuous rolling of small single weight special steel thick plate blank to thin specification finished steel plate, avoids intermediate blank offline lifting, storage and secondary repeated heating links throughout the process, ensures the continuity, stability and controllability of the rolling process from the equipment integration level, and lays a solid foundation for automatic and intelligent production.

Description

Technical Field

[0001] This invention belongs to the field of rolling processing technology for medium and thick special steel plates. Specifically, it relates to a continuous multi-fire rolling production process and equipment for small single-weight, thin-specification special steel plates. It is especially suitable for multi-fire online continuous rolling production of small single-weight, thin-specification special steel plates such as high-temperature alloys, corrosion-resistant alloys, ultra-high-strength steel, stainless steel, and tool steel. It can be widely used in high-end special steel large-scale production scenarios. Background Technology

[0002] With the rapid development of high-end fields such as aerospace, high-end equipment manufacturing, petrochemicals, and new energy, the market demand for small-weight, thin-gauge special steel plates is increasing daily, and more stringent requirements are being placed on their core indicators such as dimensional accuracy, surface quality, and mechanical properties. Special steel plates specifically refer to steel plates with special physical and chemical properties or special uses due to their unique composition, structure, and production processes. They are diverse in type and each has its own unique characteristics. Compared with ordinary steel, special steel production processes are more complex, have higher technical barriers, and are produced on a more intensive scale. Downstream applications are mainly concentrated in the high-end and special equipment manufacturing fields of industries such as automobiles, power, petrochemicals, nuclear power, environmental protection, aviation, shipbuilding, railways, and defense, making them core basic materials supporting the development of high-end manufacturing.

[0003] Small-weight, thin-gauge special steel plates (weight ≤ 2t, thickness 3mm-12mm) are made of special materials (such as high-temperature alloys, corrosion-resistant alloys, etc.), have complex compositions and poor plasticity. Conventional single-fire rolling cannot achieve precise forming. Multi-fire hot rolling process is required to gradually reduce the thickness and refine the grains in order to meet their stringent performance requirements. Therefore, multi-fire hot rolling has become the core and key process for the production of this type of special steel.

[0004] Currently, the production of hot-rolled special steel plates mainly involves various processes such as multi-fire forming, stack rolling, and furnace coil rolling. Each process has obvious limitations in its compatibility: the multi-fire forming process and the stack rolling process both require rolling the slab into intermediate billets of a certain thickness, then storing and cooling them off the production line, and finally hoisting them back onto the production line for secondary heating and rolling into finished products after re-batch assembly. Both processes require two or more fires to complete the finished product. The core drawback is that the residual heat of rolling cannot be effectively utilized, resulting in low production efficiency and yield, and a significant increase in energy consumption. At the same time, additional staffing is required for production positions such as warehouse management and workshop crane operation, and a large area is needed for storing intermediate billets. All of these factors combined result in high production costs and weak market competitiveness. The furnace coil rolling process involves first rolling the slab into a coil using a furnace coil rolling mill, and then using a flying shear to cut the coil into a plate during the uncoiling process. This process is suitable for rolling large single-weight plates and has the advantages of high output per machine hour, high production efficiency, and low unit cost. However, for small single-weight slabs of special steel, the rolling length is limited, making it difficult to adapt to the characteristics of the coil rolling process and thus difficult to apply and promote.

[0005] However, the multi-hot rolling process currently used in the industry for small-weight, thin-gauge special steel still follows the traditional special steel rolling model. It has not been specifically optimized to take into account the characteristics of small-weight, thin-gauge products and the production characteristics of special steel itself. This results in many insurmountable technical bottlenecks, severely restricting the improvement of production efficiency and product quality, and hindering the industrialization and promotion of high-end special steel. Specific technical defects are detailed below: 1) Poor production continuity, hindering large-scale production: The existing process lacks an integrated continuous rolling system; each production step is independent and severely disconnected. Intermediate billets, formed after heating and initial rolling of small single-weight slabs, require frequent hoisting and unloading by cranes to an offline storage area for temporary storage. They are then hoisted to a reheating device for reheating when subsequent processes are less busy, and then hoisted back to the rolling mill for further rolling. The entire production process involves numerous offline hoisting and storage steps, with each hoisting and storage session taking 15-20 minutes, severely slowing down the production cycle. This process not only leads to rapid temperature loss in intermediate billets during hoisting and storage (temperature drop rate can reach over 50℃ / min), severely disrupting the temperature stability of subsequent rolling operations and affecting rolling accuracy; it also easily causes surface scratches and edge deformation of intermediate billets due to collisions and friction during hoisting, with scratch depths reaching over 0.3mm. This directly reduces product dimensional accuracy and surface quality, resulting in a consistently low product qualification rate (usually below 85%). This makes it impossible to meet the stringent quality requirements for special steel plates in aerospace, high-end equipment manufacturing, and other fields, limiting the high-end application of the product. Furthermore, small, thin-gauge special steel intermediate billets are inherently thin and have poor rigidity, making them prone to plastic deformation during offline hoisting and storage. This further exacerbates product quality defects, causing some severely deformed intermediate billets to be unsuitable for subsequent rolling, resulting in raw material waste and further increasing production costs.

[0006] 2) High production costs and extremely low resource and energy utilization: On the one hand, frequent hoisting and storage of intermediate billets require a large number of lifting equipment and operators, significantly increasing the workforce on the production line (an additional 8-12 hoisting and storage management personnel are needed per production line). At the same time, a large area is required for storage of intermediate billets, increasing site rental and construction costs, indirectly leading to a 15%-20% increase in the production cost per ton of steel. On the other hand, the existing process has an extremely low utilization rate of the residual heat from rolling. The temperature loss caused by hoisting and storage of intermediate billets cannot be recovered, and the intermediate billets need to be reheated to meet the temperature requirements of subsequent rolling. This not only increases energy consumption such as electricity and fuel (energy consumption per ton of steel increases by 10%-15%), but also goes against the current trend of industrial environmental protection, energy conservation, and green low-carbon development, and is inconsistent with the national industrial energy conservation and consumption reduction policy.

[0007] 3) Poor adaptability of heating equipment, and the heating effect cannot meet production needs: Existing heating equipment is mostly traditional fixed heating furnaces with unreasonable structural design. They have not been specifically optimized for the heating characteristics of small single-weight and thin-gauge special steel intermediate billets, resulting in two major problems: First, the temperature field distribution is uneven, with temperature differences in different areas of the furnace reaching more than 30℃. After heating, the temperature uniformity of the upper and lower surfaces, edges and center of the intermediate billet is poor, which cannot meet the temperature accuracy requirements of multi-fire rolling (temperature uniformity ≤ ±5℃). This leads to defects such as uneven thickness and cracks in the plate during subsequent rolling. Second, the equipment has poor adaptability. Single-type heating equipment cannot flexibly adapt to the heating needs of different types of special steel such as high-temperature alloys, corrosion-resistant alloys and stainless steel. It also cannot adapt to the heating of small single-weight intermediate billets with different widths and lengths. It is necessary to replace the heating equipment or make significant adjustments to the process parameters to meet production needs, further reducing production efficiency and limiting the diversified and large-scale production of high-end special steel.

[0008] 4) Loose process connections and low production efficiency: In the existing process, the core processes such as heating, rolling, temperature compensation, and straightening lack a coordinated linkage mechanism. Each piece of equipment operates independently and is not compatible with each other. The waiting time between processes is long, and it is impossible to achieve parallel operation of multiple billets. This results in a low processing speed of the rolling line (usually less than 120m / min). The annual processing capacity of a single production line is less than 50,000 tons, which cannot meet the market's large-scale demand for small, thin-specification special steel and is difficult to match the development pace of downstream high-end fields.

[0009] In summary, existing multi-fire hot rolling processes and equipment for small-weight, thin-gauge special steels suffer from numerous significant technical drawbacks, including poor production continuity, high production costs, low resource and energy utilization, poor heat compensation effects, and low production efficiency. These shortcomings prevent them from meeting the core requirements of high-efficiency, energy-saving, high-quality, and large-scale production of high-end special steels, and also fail to align with the current mainstream trend of green, low-carbon, and intelligent industrial development. Therefore, developing a process and equipment technology that can overcome these technical bottlenecks and achieve continuous online multi-fire rolling of small-weight, thin-gauge special steels has become a pressing technical challenge in the special steel rolling field, and is also the initial research objective and core starting point of this invention. Summary of the Invention

[0010] In view of this, the purpose of this invention is to solve the above problems and provide a continuous multi-fire rolling production process and equipment for small single-weight, thin-specification special steel plates. The core equipment is seamlessly connected by conveyor rollers, and an additional vertical lifting circulating heating furnace is added to achieve online continuous heating for multiple fires. At the same time, a multi-billet parallel linkage method is adopted to completely solve the problems of offline hoisting of intermediate billets and poor continuity in the existing process.

[0011] To achieve the above objectives, the present invention provides the following technical solution: A continuous multi-fire rolling production equipment for small-weight, thin-specification special steel plates includes a slab heating furnace, a four-roll reversible hot rolling mill, a vertical lifting circulating heating furnace, a hot straightener, a fixed-length shearing unit, a stack collection device, a conveying roller table, and a signal control system. The output end of the slab heating furnace is connected to the input end of the four-high reversible hot rolling mill via a conveyor roller conveyor, which conveys the heated slab to the rolling mill. There are two vertical lifting circulating heating furnaces, which are respectively set on the side of the input and output roller table of the four-roll reversible hot rolling mill. The two vertical lifting circulating heating furnaces are respectively connected to the input and output roller table of the four-roll reversible hot rolling mill through the conveying roller table. They are used to receive intermediate billets online for reheating and send the reheated intermediate billets back to the four-roll reversible hot rolling mill for further rolling. The output end of the four-roll reversible hot rolling mill is connected in sequence to the hot straightening machine, the fixed-length shearing unit and the stack collection device via conveyor rollers; the equipment is connected in series via conveyor rollers to form a closed-loop continuous production line, so that the intermediate billet can be rolled online continuously with multiple fires without offline hoisting and storage. The signal control system is connected to the slab heating furnace, the four-roll reversible hot rolling mill, the vertical lifting circulating heating furnace, and the conveyor roller conveyor, and is used to coordinate the signal interaction and collaborative linkage between the various devices.

[0012] Furthermore, the vertical lifting circulating heating furnace includes a vertical annular furnace body, an annular rotating mechanism, a workstation lifting device, a zoned electric heating device, and an intelligent temperature control system. The vertical annular furnace body adopts a closed annular structure, with multiple independent heating stations evenly arranged around the circumference of the furnace body. The furnace body has a reserved inlet and outlet, which are respectively connected to the conveyor rollers. The annular rotating mechanism includes a geared motor, an annular hub, and spokes. The geared motor is connected to the annular hub via a coupling. Multiple station lifting devices for supporting intermediate blanks are distributed circumferentially on the annular hub. Each station lifting device is connected to the annular hub via spokes. The geared motor drives the annular hub to rotate at a constant speed, which in turn drives the lifting devices at each station to rotate in a circular motion within the vertical annular furnace, so that the intermediate billet can be uniformly heated during the annular motion. The partitioned electric heating device is embedded in the insulation layer of the inner wall of the vertical annular furnace, forming multiple heating partitions corresponding to the heat replenishment stations distributed along the circumference. The intelligent temperature control system is connected to the zoned electric heating device and the ring rotation mechanism via signals, and is used to automatically adjust the heating power of each zone and the ring rotation speed based on temperature feedback.

[0013] Furthermore, the pallet of the workstation lifting device is made of heat-resistant steel, the surface of the pallet is covered with a high-temperature resistant ceramic anti-scratch coating, and the edge of the pallet is provided with a flexible guard to prevent surface scratches and slippage of the intermediate billet during the cyclic rotation and reheating process. Each heating zone of the partitioned electric heating device is equipped with an electric heating element, which, together with the forced hot air circulation mechanism installed on the top of the furnace body, achieves uniform temperature distribution inside the furnace and controls the temperature difference between different areas inside the furnace to ≤±3℃. The vertical annular furnace body is equipped with a flexible guiding mechanism and a sealing structure at the inlet and outlet, so that the working temperature inside the furnace is stable at 500℃-980℃, and the temperature compensation and control accuracy is ≤±5℃. The ring-shaped rotating mechanism is equipped with an energy accumulator, which is connected to a geared motor through a hydraulic pipeline. It is used to recover the gravitational potential energy on the lowering side of the workstation lifting device and circulate it for the workstation lifting operation on the upper side.

[0014] Furthermore, the roller surface of the conveyor is treated with a wear-resistant and scratch-resistant coating, and the outside of the roller is equipped with a heat insulation protective layer and an intermittent heating device to control the temperature drop during the transfer of the plate within 20℃ / min; the roller running speed is 1m / s-3m / s and has stepless speed regulation.

[0015] Furthermore, the hot straightener adopts a front and rear mother-daughter straightener tandem arrangement structure, coaxially arranged in series along the center line of the conveyor roller table; The mother straightener is a large-diameter straightener, located at the front of the tandem, and is used for rough straightening of thicker intermediate billets; the daughter straightener is a small-diameter straightener, located at the rear of the tandem, and is used for fine straightening of thinner finished sheets. The mother straightener and the daughter straightener are fixedly connected by a rigid bracket and a transition roller table is set to achieve seamless connection. The mother and daughter straighteners are equipped with a collaborative linkage control system. A plate shape detection sensor is installed at the exit of the mother straightener to collect the warp and waviness plate shape data of the intermediate billet after rough straightening in real time and transmit the data to the signal control system. The signal control system automatically adjusts the straightening speed, roller gap and straightening pressure of the daughter straightener according to the plate shape data, the material of the intermediate billet and the target thickness of subsequent rolling. It constructs a closed-loop control logic that feeds back the rough straightening parameters to the fine straightening parameters for adaptive adjustment, so as to achieve precise matching of rough straightening and fine straightening parameters.

[0016] Furthermore, the signal control system adopts a PLC controller to achieve bidirectional signal interaction with the slab heating furnace, the four-roll reversible hot rolling mill, the vertical lifting circulating heating furnace, and the conveyor roller conveyor. The four-roll reversible hot rolling mill collects rolling load, roll gap opening and rolling speed parameters in real time, sends steel demand signals to the slab heating furnace and receives slab ready signals, receives intermediate billet reheating completion signals to the vertical lifting circulating heating furnace, and sends speed matching signals to the conveyor roller table to ensure seamless connection of each process.

[0017] Furthermore, the slab heating furnace adopts a side-in, side-out arrangement, and the furnace opening adopts a single-door sealing structure; the furnace is equipped with a zoned precision temperature control system, which is divided into multiple heating zones along the length of the furnace, and each heating zone is equipped with multiple sets of electric heating elements, with a temperature control accuracy of ≤±3℃; the atmosphere inside the furnace is controlled by a slight positive pressure; when the intermediate billet is discharged from the vertical lifting circulating heating furnace after being reheated, the slab heating furnace suspends the discharge operation to match the steel discharge rhythm of the vertical lifting circulating heating furnace, so as to achieve precise matching of the rolling rhythm.

[0018] A continuous multi-fire rolling process for small-weight, thin-gauge special steel plates, using the equipment described above, is employed for the continuous multi-fire rolling production of various types of small-weight special steels, including high-temperature alloys, corrosion-resistant alloys, ultra-high-strength steels, stainless steels, and tool steels. The production process utilizes a multi-slab parallel and multi-fire online continuous rolling method, specifically including the following steps: After being heated to the preset target rolling temperature in a slab walking beam furnace, the small single-weight special steel slab is sent to a four-roll reversible hot rolling mill for reversible rolling to form an intermediate slab. When the temperature of the intermediate billet drops below the rollable temperature range, the intermediate billet is transferred online via conveyor rollers to a vertical lifting circulating heating furnace for reheating. While the intermediate billet is being reheated in the vertical lifting circulating heating furnace, the next slab is taken out of the slab heating furnace and sent to a four-high reversible hot rolling mill for rolling, realizing the parallel operation of rolling and reheating processes, and the parallel linkage operation of multiple billets. After being reheated to the preset rolling temperature, the intermediate billet is sent back to the four-high reversible hot rolling mill via conveyor rollers to continue rolling, repeating the rolling and reheating steps until the preset finished thickness is reached. The finished boards are straightened by a hot straightening machine, cut to length by a fixed-length shearing unit, and finally collected into stacks by a stacking and collecting unit, realizing online continuous production from board blank to finished product.

[0019] Furthermore, to address the multi-pass rolling requirements of different types of special steel, a differentiated arrangement of the reheating furnace is adopted: intermediate billets requiring two reheating passes are sent to the vertical lifting and circulating heating furnace following the four-roll reversible hot rolling mill for reheating to ensure that the temperature of the finishing rolling process meets the standards; intermediate billets requiring three reheating passes are sent to the vertical lifting and circulating heating furnace preceding the four-roll reversible hot rolling mill for reheating to ensure that the temperature of the next roughing rolling pass is stable.

[0020] Furthermore, the slab heating furnace is equipped with differentiated heating parameters according to the slab material: the heating rate for high-temperature alloys is 5-8℃ / min, and the heating rate for stainless steel is 8-12℃ / min; during the heating process, the heating power density is dynamically adjusted according to the heating stage: the power density during the preheating stage is controlled at 15-20kW / m³. 2 During the heating phase, the power density increases to 25-30 kW / m³. 2 During the heat preservation stage, the power density drops to 10-15 kW / m².2 .

[0021] Compared to existing small-scale, multi-stage hot rolling processes and equipment, this invention overcomes the shortcomings of existing technologies through innovative process design, equipment layout, and process linkage control. Its core advantages and beneficial effects are as follows: 1) Significantly improved production continuity and scale, completely breaking through industry bottlenecks: This invention constructs an integrated system of "multi-slab parallel linkage + multi-heat online continuous rolling", which seamlessly connects core equipment such as slab heating furnace, four-roll reversible hot rolling mill, and vertical lifting and reheating furnace through dedicated transport rollers to form a closed-loop production process without interruption, realizing online continuous and large-scale production of small single-weight slabs from feeding, heating, rolling, reheating to finished product collection. This process completely eliminates redundant steps such as offline hoisting and storage of intermediate billets in the existing process, effectively solving the core pain points of poor production continuity and slow production cycle in the existing process. At the same time, it avoids problems such as rapid temperature loss (temperature drop rate reduced from more than 50℃ / min to less than 20℃ / min), surface scratches (scratch depth reduced from more than 0.3mm to no obvious scratches) and plastic deformation that occur during hoisting and storage of intermediate billets. This significantly improves the production cycle and increases the annual processing capacity of a single production line from less than 50,000 tons to 80,000-100,000 tons, truly realizing the large-scale production of small, thin-gauge special steel.

[0022] 2) Outstanding environmental and energy-saving effects, aligning with the trend of green industrial development, and quantifiable energy-saving benefits: This invention relies on the intelligent temperature control design and potential energy recovery technology of the vertical lifting and reheating furnace to innovatively maximize the utilization of rolling residual heat, significantly reducing energy consumption losses caused by repeated slab heating. Combined with the zoned precise temperature control of the slab heating furnace and the temperature drop prevention design of the dedicated transport roller conveyor, the energy consumption per ton of steel is reduced by more than 10%-15% compared to existing processes. At the same time, the potential energy recovery system of the vertical lifting and reheating furnace can increase energy utilization by more than 45%, fully aligning with the current industrial environmental protection, energy conservation, green and low-carbon development direction and the national industrial energy conservation and consumption reduction policy. The reduction in energy consumption directly compresses production costs, further enhancing the market competitiveness of products, and possessing significant economic and environmental benefits.

[0023] 3) Significantly optimized human resources and site investment, resulting in a substantial improvement in enterprise economic benefits: This invention completely eliminates the intermediate billet hoisting and storage process, eliminating the need for additional intermediate billet storage areas and significantly reducing the site area required; at the same time, it eliminates the need for a large number of crane operators and warehouse staff, reducing the workforce by 8-12 people per production line, effectively reducing human resource management costs, site rental and construction costs, and indirectly reducing the production cost per ton of steel by 15%-20%, significantly improving the enterprise's economic benefits and market competitiveness, and meeting the needs of intensive production.

[0024] 4) Significantly improved production efficiency and processing capacity, breaking through efficiency bottlenecks: This invention achieves synchronous parallel operation of rolling and reheating processes through a multi-billet parallel linkage mode, integrated equipment serial design, and process collaborative linkage control, completely changing the limitation of the existing process of "single billet serial operation". The rolling line processing speed is stabilized at 50m / min~180m / min, which is a significant improvement compared to the existing process (usually below 120m / min). The production cycle is shortened by more than 30% compared to the existing process, effectively breaking through the technical bottleneck of low efficiency in multi-fire rolling of small single-weight special steel, and can quickly respond to the market's demand for large-scale special steel of small single weight.

[0025] 5) Significantly improved product quality stability, meeting stringent requirements in high-end fields: This invention, through innovative designs such as zoned precise temperature control in the slab heating furnace (temperature control accuracy ≤ ±3℃), dynamic precise temperature compensation in the vertical lifting and compensation furnace (temperature uniformity after compensation ≤ ±5℃), dedicated anti-scratch transport rollers, and tandem straightening of the mother-daughter straighteners, effectively avoids temperature loss and surface scratches during intermediate slab transfer, ensuring precise and controllable rolling temperatures for each pass. This results in finished plate thickness tolerance controlled within ±0.8mm, plate shape accuracy ≤2mm / m, and a product qualification rate increased from below 85% to over 98%. The dimensional accuracy, surface quality, and microstructure uniformity of the finished plates are superior to existing processes. This invention can be widely applied in the production of high-end special steel, especially suitable for multi-fire online continuous rolling production of small, single-weight, thin-specification special steel plates, accurately meeting the stringent requirements for high-quality special steel plates in high-end fields such as aerospace, high-end equipment manufacturing, petrochemicals, new energy, and marine engineering.

[0026] Overall, this invention possesses significant advantages such as energy saving, high efficiency, low cost, high quality, and wide applicability. It can quickly gain acceptance from special steel manufacturers, achieving industrial application without large-scale modifications to existing production sites, and has extremely high market promotion and application value and industrialization prospects. Its promotion and application can help special steel manufacturers significantly enhance their core competitiveness, promote the transformation and upgrading of the special steel rolling industry towards continuous, intelligent, energy-saving, and high-end directions, and help my country's high-end special steel industry break through technological bottlenecks and achieve independent control.

[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is an elevation view of the continuous multi-fire rolling production equipment for small-weight, thin-specification special steel plates in this invention.

[0029] Figure 2 for Figure 1 Top view.

[0030] Figure 3 This is an elevation view of the vertical lifting and circulating heating furnace in this invention.

[0031] Figure 4 This is a plan view of the vertical lifting and circulating heating furnace in this invention.

[0032] Figure 5 This is a schematic diagram of the continuous multi-fire rolling production process for small-weight, thin-specification special steel plates in this invention.

[0033] Reference numerals: 1-Heating furnace front centering device; 2-Slab walking beam heating furnace; 3-Mill inlet vertical lifting circulating heating furnace; 4-Mill inlet centering device; 5-Four-high reversible hot rolling mill; 6-Mill outlet centering device; 7-Mill outlet vertical lifting circulating heating furnace; 8-Straightener; 9-Hot segment shear; 10-Stacking plate collection device; 11-Reheating furnace charging device; 12-Conveying roller conveyor; 14-Annular rotating mechanism; 15-Station lifting device; 16-Spoke. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0037] Example 1 like Figures 1-4 As shown, this is a continuous multi-fire rolling production equipment for small-weight, thin-gauge special steel plates. It includes a slab walking beam furnace 2, a vertical lifting circulating furnace 3 at the mill inlet, a four-high reversible hot rolling mill 5, a vertical lifting circulating furnace 7 at the mill outlet, a mother-daughter straightener 8, a fixed-length shearing unit 9, and a stack collection device 10, arranged sequentially. A furnace front centering device 1 is installed in front of the slab walking beam furnace 2; a mill inlet centering device 4 is installed between the vertical lifting circulating furnace 3 at the mill inlet and the four-high reversible hot rolling mill 5; and a mill outlet centering device 6 is installed between the four-high reversible hot rolling mill 5 and the vertical lifting circulating furnace 7 at the mill outlet. All equipment is connected in series via conveyor rollers 12 to form a closed-loop continuous production line, enabling online continuous multi-fire rolling of intermediate slabs without offline hoisting and storage. The signal control system is connected to the slab walking beam furnace 2, the four-roll reversible hot rolling mill 5, the vertical lifting and circulating furnace 3 at the mill inlet, the vertical lifting and circulating furnace 7 at the mill outlet, and the conveyor roller conveyor 12. This system coordinates the signal interaction and collaborative operation between the various devices. The specific layout of each device is as follows: Slab Walking Beam Furnace 2: Adopting a side-in, side-out layout, the furnace opening features a single-door sealed structure, effectively reducing temperature loss at the furnace opening and controlling temperature drop within 30℃. The furnace is equipped with a zoned precision temperature control system, dividing it into three heating zones along its length. Each zone has eight sets of 25kW silicon molybdenum rod heating elements, resulting in a total heating power of 600kW and a temperature control accuracy of ≤±3℃. The silicon molybdenum rods are evenly arranged along the furnace width, with a spacing of 300mm and an inclination of 15° to the furnace sidewall. The furnace atmosphere is controlled with a slight positive pressure, ranging from 50-100Pa. The furnace body uses a full-fiber insulation layer, 300mm thick, with a thermal conductivity ≤0.06W / (m·K), significantly reducing heat loss. During heating, the heating power density is dynamically adjusted according to the heating stage: in the preheating stage (slab temperature 20-500℃), the power density of all three heating zones is controlled at 15-20kW / m². 2 During the heating stage (slab temperature 500-1000℃), the power density of the head heating zone is increased to 25-30kW / m².2 The heating zones in the middle and rear sections are maintained at 20-25 kW / m². 2 During the heat preservation stage (slab temperature 1000-1150℃), the power density of the three heating zones all decreased to 10-15 kW / m². 2 The heating rate is tailored to the slab material: 5-8℃ / min for high-temperature alloys and 8-12℃ / min for stainless steel. The target heating temperature is 1050-1150℃ (1100-1150℃ for high-temperature alloys and 1050-1100℃ for stainless steel), with temperature uniformity ≤ ±5℃. The heating and holding time is strictly determined based on the slab thickness: for every 10mm increase in thickness, the holding time is extended by 20min. For example, the holding time for an 80mm thick high-temperature alloy slab is 160min, and for a 150mm thick stainless steel slab, it is 300min. Suitable slab specifications: single weight ≤ 2t, thickness 80-150mm, width 600-2100mm, length 1500-2500mm. When the intermediate slab is reheated in the vertical lifting circulating heating furnace and then exits, the slab walking beam furnace 2 suspends its exit operation to match the steel output rhythm of the vertical lifting circulating heating furnace, achieving precise matching of the rolling rhythm.

[0038] The four-high reversible hot rolling mill (model 5) has a roll length of 2250mm, a work roll diameter of φ550mm, a support roll diameter of φ1500mm, and a roll hardness of HRC60-65. It employs an integral cast steel frame with a frame rigidity ≥12000kN / mm, ensuring structural stability during rolling. A material identification sensor (with an accuracy of ±0.1mm) is installed on the mill inlet side, automatically identifying different types of special steels such as high-temperature alloys, corrosion-resistant alloys, and stainless steel. Combined with the actual thickness and temperature data of the slab / intermediate billet, it automatically matches specific rolling parameters. The mill is equipped with a hydraulic roll bending device with a bending force range of 0-2000kN, effectively controlling the slab shape accuracy. The rolling parameters for different materials are as follows: High-temperature alloy (GH4169): rolling pressure 28000-35000kN, rolling speed 1-2m / s, pass reduction gradually decreasing (15-18mm for the first pass, and 2-3mm for each subsequent pass), bending force 1200-1800kN; Stainless steel (304): rolling pressure 20000-30000kN, rolling speed 2-3m / s, pass reduction 12-15mm (first pass) gradually decreasing to 5-8mm (last pass), bending force 800-1200kN; Corrosion-resistant alloy (Hastelloy C-276): rolling pressure 30000-32000kN, rolling speed 1.5-2.5m / s, pass reduction 10-12mm, bending force 1500-2000kN. All rolling parameters are adjusted to an accuracy of ±100kN (rolling pressure) and ±0.1m / s (rolling speed). The intermediate billet undergoes 4-6 reversible rolling passes to form an intermediate billet with a thickness of 15-50mm (thickness tolerance ±0.8mm). The number of finishing rolling passes is determined based on the finished product thickness: 4-5 passes are used when the finished product thickness is 3-5mm, with a single reduction of 0.5-1mm; 3-4 passes are used when the finished product thickness is 5-12mm, with a single reduction of 1-2mm.

[0039] Vertical lifting circulating heating furnace 3 at the mill inlet and vertical lifting circulating heating furnace 7 at the mill outlet: These two vertical lifting circulating heating furnaces have identical structures, respectively located on the side of the input and output roller conveyors of the four-roll reversible hot rolling mill 5. Both have a closed vertical annular structure (borrowing from the principle of Ferris wheel rotation and multi-station parallel operation, adopting a closed furnace body design). The overall furnace body dimensions are 4800mm outer diameter × 3500mm inner diameter × 6000mm height. The vertical annular furnace body is constructed using all-fiber aluminosilicate spun blanket modules to form a closed annular structure with a 400mm thick insulation layer (thermal conductivity ≤0.05W / (m·K)). The furnace shell is made of Q235B steel plate and structural steel (steel plate thickness 16mm), providing high structural strength and excellent insulation performance. The bottom of the furnace body is fixed to the workshop floor with expansion bolts (1000mm spacing). The furnace body has pre-reserved feed inlets and outlets on its circumference, which seamlessly connect with the conveyor roller conveyor 12 (connection accuracy ≤2mm).

[0040] The annular rotating mechanism 14 is installed at the center of the top and bottom of the furnace body. A 75kW geared motor (model Y2-280M-4) is installed at the top, connected to the annular hub via a coupling. An annular guide rail (model HJG-300, material Cr12MoV) is installed at the bottom. The annular hub is connected to the station lifting device 15 via eight spokes 16 (material 45 steel, cross-section 150mm×100mm), forming a Ferris wheel-like "hub-spoke-cabin" transmission structure. The geared motor drives the annular hub to rotate at a uniform speed, causing the six station lifting devices 15 to circulate along the vertical annular furnace body. The rotation speed is 0.5-1 r / min (adjustment accuracy ±0.1 r / min), which can be dynamically adjusted according to the reheating time, ensuring precise and controllable reheating time for each station within the furnace.

[0041] Six sets of station lifting devices 15 are evenly fixed to the ends of the spokes 16. The support plates are made of Cr25Ni20 heat-resistant steel (20mm thick) and covered with a 3mm thick Al2O3 high-temperature resistant ceramic anti-scratch coating (using plasma spraying technology, spraying temperature 800℃). The support plates are 2250mm long and 4000mm wide, with a load-bearing capacity of ≥2.5t / set. The edges of the support plates are equipped with 50mm high-flexibility baffles (made of high-temperature resistant silicone) to effectively prevent surface scratches and slippage of the intermediate billets during circulation and reheating. The reheating furnace loading device 11 is set at the feed inlet of the vertical lifting circulating heating furnace and is used to smoothly load the intermediate billets into the station lifting devices 15. The six sets of station lifting devices 15 are arranged in a rotating parallel manner, which can realize the feeding, reheating, and unloading of multiple intermediate billets at the same time, greatly improving the reheating efficiency.

[0042] The zoned electric heating device is embedded in the insulation layer of the furnace body, dividing the ring-shaped furnace into 6 heating zones, corresponding to 6 supplementary heating stations. Each zone is equipped with 6 sets of 25kW Cr20Ni80 resistance wire heating elements, spaced 400mm apart, in conjunction with a forced hot air circulation mechanism (high-temperature resistant centrifugal fan, 8000m³ / h) installed on one side of the top of the furnace body. 3 / h, air pressure 800Pa, air outlet connected to the inside of the furnace body, air inlet connected to the return air channel on the side of the furnace body), to achieve uniform temperature distribution in the furnace, and temperature difference between different areas in the furnace ≤±3℃.

[0043] Flexible graphite sealing curtains (50mm thick, with a gap of ≤5mm between the curtain and the lifting device at the workstation) are installed at the furnace inlet and outlet. A labyrinthine sealing structure (sealing gap ≤2mm, filled with high-temperature resistant sealing cotton) is used at the connection between the annular rotating mechanism and the furnace body. Combined with the overall furnace insulation layer, this effectively reduces temperature loss at the furnace opening and rotating parts (furnace opening temperature drop ≤25℃ / h). The furnace operating temperature is stable at 500℃-980℃, with a temperature control accuracy of ≤±5℃, ensuring uniform temperature across the entire cross-section of the intermediate billet and meeting the stringent temperature accuracy requirements of multi-pass rolling. Flexible guiding mechanisms are installed at both the furnace inlet and outlet. These mechanisms consist of two sets of guide rollers (material Cr25Ni20, diameter φ100mm, length 2250mm), with an adjustable guide gap of 5-15mm. The guide roller spacing is controlled by adjusting bolts to ensure smooth entry and exit of the intermediate billet from the furnace and the reheating station.

[0044] The annular rotating mechanism 14 is equipped with a 150L accumulator, which is connected to a geared motor and rotating bearing via hydraulic lines. It can intelligently recover the gravitational potential energy from the lowering side (lower half of the annular furnace body) of the lifting device 15 and circulate it for lifting operations on the ascending side (upper half of the annular furnace body). The control logic is as follows: when the lowering speed of the lifting device is ≥0.3m / min, the accumulator begins storing energy and stops when the storage pressure reaches 16MPa; when the lifting device requires power to ascend, the accumulator releases energy, working in conjunction with the geared motor to drive the annular rotation, thereby increasing energy utilization by more than 45%.

[0045] The intelligent temperature control system employs a PID fuzzy control algorithm, linked with infrared temperature measurement devices (temperature range 500-1200℃, accuracy ±2℃, installed above the furnace inlet, outlet, and each reheating station, with the lens facing the intermediate billet surface and a sampling frequency of 1 time / second). This allows for real-time acquisition of the intermediate billet surface temperature data, automatically adjusting the power of the heating elements in each zone and the rotation speed of the ring-shaped rotating mechanism to achieve dynamic and precise reheating of the intermediate billet. This vertical lifting circulating heating furnace is suitable for the reheating needs of small, single-weight special steel intermediate billets of various types (high-temperature alloys, corrosion-resistant alloys, stainless steel, etc.) and specifications (width 600mm-2100mm, length 1500mm-2500mm, thickness 15mm-50mm).

[0046] Mother-daughter straightener 8: It adopts a front and rear mother-daughter straightener tandem integrated arrangement structure, coaxially arranged along the center line of conveyor roller 12, with a center line deviation of ≤1.5mm. The two straighteners are fixedly connected by an integrated rigid bracket (material Q235B cast steel, thickness 30mm, length 1800mm). The bottom of the bracket is fastened to the workshop floor with expansion bolts to ensure the stability of the tandem structure.

[0047] The mother straightener is a large-diameter, heavy-duty straightener located at the front of the tandem, specifically designed for rough straightening of thick intermediate billets (15-50mm thick) and rolled semi-finished products. It has seven straightening rolls, with a work roll diameter of φ280mm (20% larger than traditional rough straighteners) and a roll body length of 2250mm, perfectly matching the 12 roll body lengths of the rolling mill and conveyor rollers. The work rolls are made of Cr12MoV wear-resistant alloy with a surface hardness of HRC62-65, and the roll surface is polished (surface roughness Ra≤0.8μm). Combined with an adaptive roll gap adjustment mechanism (adjustment accuracy ±0.1mm), the roll gap can be automatically adjusted according to the thickness of the intermediate billet. The straightening speed is fixed at 30m / min, and the straightening pressure ranges from 800 to 1500kN (800-1000kN when the intermediate billet thickness is 15-30mm, and 1200-1500kN when it is 30-50mm), which can effectively eliminate the warping and wave deformation of the intermediate billet caused by rolling.

[0048] The sub-straightening machine is a small-diameter precision straightening machine located at the rear of the tandem, specifically designed for precision straightening of thin-gauge finished plates (3-12mm thick). It has 11 straightening rollers (2 more than traditional precision straightening machines), with a work roller diameter of φ120mm and a roller body length of 2250mm, consistent with the lengths of the mother straightening machine and rolling mill rollers. The work rollers are made of flexible, wear-resistant material (Cr25Ni20 heat-resistant alloy + 3mm thick Al2O3 ceramic coating), possessing both high-temperature resistance and scratch resistance. A flexible buffer adjustment structure between the rollers allows for dynamic adjustment of the straightening pressure (500-1000kN range, 500-700kN for 3-5mm thickness, and 800-1000kN for 5-12mm thickness) and straightening speed according to the thickness and material of the finished plate. This prevents defects such as plastic deformation and edge curling in thin-gauge plates during precision straightening, ensuring a plate shape accuracy of ≤2mm / m.

[0049] A dedicated transition roller conveyor (1800mm long, 2250mm roller body length) is installed between the two straighteners, seamlessly connecting with the roller conveyors of the two straighteners (connection gap ≤1mm). The running speed of the transition roller conveyor is synchronized with the straightening speed of the front and rear straighteners (speed deviation ≤0.1m / s), avoiding temperature loss, surface scratches, and secondary deformation of the sheet material during the transition process. The mother and daughter straighteners are detachably connected to the integrated rigid support using bolts, allowing for flexible adjustment of the distance between the two straighteners according to production needs (adjustment range 1800-2200mm) to accommodate the straightening requirements of sheet materials of different lengths, while also facilitating equipment inspection, maintenance, and replacement.

[0050] The master and slave straighteners are equipped with a collaborative control system that shares a PLC controller with the signal control system, constructing a closed-loop control logic of "coarse straightening parameter feedback - fine straightening parameter adaptive adjustment". A shape detection sensor (detection accuracy ±0.1mm, sampling frequency 1 time / 0.1s) is installed at the exit of the master straightener to collect real-time data on the warp and waviness of the intermediate slab after coarse straightening, and transmits the data to the PLC control system. Based on the shape data, the material of the intermediate slab, and the target thickness for subsequent rolling, the control system automatically adjusts the straightening speed, roll gap, and straightening pressure of the slave straightener to achieve precise matching of coarse and fine straightening parameters. For example, when the master straightener detects that the warp of the intermediate slab is ≥1.5mm / m, the control system automatically reduces the straightening speed of the slave straightener by 20m / min and increases the straightening pressure by 100kN to ensure that the shape meets the standards after fine straightening.

[0051] Conveyor Roller 12: Utilizing φ160mm×18mm heat-resistant steel rollers (material 1Cr18Ni9Ti), with a roller body length of 2250mm (consistent with the mill roller body length) and a roller spacing of 300mm, precisely matching the dimensions of small, thin sheet metal to prevent slippage and collisions during transport. The roller surface is coated with a plasma-sprayed wear-resistant and scratch-resistant coating (coating thickness 0.8mm, hardness HV800-1000), improving wear resistance by more than 3 times and effectively preventing scratches on the sheet metal surface. A 50mm thick rock wool insulation layer is added to the outside of the roller conveyor, wrapped with a 0.5mm thick aluminum foil reflective layer. Combined with an intermittent heating device (heating power 1.5kW / m), the temperature drop during sheet metal transport can be controlled within 20℃ / min, ensuring rolling temperature stability. The roller conveyor operates at a speed of 1-3m / s, with stepless speed adjustment, enabling rapid, stable, and low-temperature transport of slabs, intermediate billets, and finished sheets.

[0052] Pallet Collection Device 10: Adopting a "layered buffer + precise alignment" design, it is equipped with flexible buffer trays (buffer stroke 50mm, buffer force adjustable from 0-500N). The trays are made of polyurethane to prevent surface scratches and edge deformation during the stacking of finished boards. It features a hydraulic lifting system (lifting speed 0.5-1.5m / min) to ensure smooth lifting of the pallets. The maximum pallet height is 1000mm, allowing for the neat collection of sheared finished boards into stacks according to specifications.

[0053] Signal Control System: A PLC controller is used to achieve bidirectional signal interaction with the slab walking beam furnace 2, the four-roll reversible hot rolling mill 5, the vertical lifting circulating furnace 3 at the mill inlet, the vertical lifting circulating furnace 7 at the mill outlet, and the conveyor roller table 12. The signal transmission delay is ≤0.5s. The four-roll reversible hot rolling mill 5 collects rolling load, roll gap opening, and rolling speed parameters in real time (collection frequency 1 time / 0.1s), sends a steel demand signal (including target slab material, size, and starting rolling temperature requirements) to the slab walking beam furnace 2, and receives slab ready signals (including actual heating temperature and furnace exit timing). It also receives intermediate slab reheating completion signals (including actual temperature after reheating and intermediate slab thickness) from the vertical lifting circulating furnace and sends speed matching signals (speed deviation ≤0.1m / s) to the conveyor roller table 12 to ensure seamless connection of each process.

[0054] Example 2 like Figures 1-5 As shown, using the equipment described in Example 1, taking a small single-unit slab of high-temperature alloy GH4169 (single weight ≤ 2t, thickness 100mm, width 1500mm, length 2000mm) as an example, a three-heat-compensated continuous multi-heat rolling process is performed. The specific process flow is as follows: Step 1: Slab hoisting and precise heating.

[0055] Small single-weight special steel slabs are lifted by a workshop crane (model QD20 / 5t) using a flexible lifting device (nylon material, lifting device width 200mm) to the centering device 1 in front of the slab walking beam furnace 2 for centering and positioning. Then, they are smoothly transferred into the slab walking beam furnace 2 via conveyor rollers 12 (running speed 0-120m / min, stepless speed adjustment according to slab thickness). During the transfer, the deviation between the slab centerline and the roller centerline is ≤2mm. The furnace-internal zoned temperature control system is matched with high-temperature alloy heating parameters: heating rate 5-8℃ / min, preheating stage (slab temperature 20-500℃), power density 15-20kW / m³. 2 During the heating stage (slab temperature 500-1000℃), the power density of the head heating zone is increased to 25-30kW / m². 2 During the heat preservation stage (slab temperature 1000-1150℃), the power density drops to 10-15kW / m². 2 The slab is precisely heated to 1100-1150℃ and held for 200 minutes (for a thickness of 100mm, the holding time is extended by 20 minutes for every additional 10mm), with temperature uniformity ≤ ±5℃. After heating, wait for the four-roll reversible hot rolling mill 5 to issue a steel demand signal (signal transmission delay ≤ 0.5s).

[0056] Step 2: First flexible reversible rolling.

[0057] After the four-high reversible hot rolling mill 5 issues a steel demand signal, the slab is rapidly exited from the slab walking beam furnace 2 (running speed 120m / min), centered by the mill inlet centering device 4, and then fed into the four-high reversible hot rolling mill 5. The mill material identification sensor automatically identifies the high-temperature alloy material and matches the specific rolling parameters: rolling pressure 28000-35000kN, rolling speed 1-2m / s, and gradually decreasing reduction per pass (15-18mm for the first pass, and 2-3mm for each subsequent pass). The hydraulic bending roll device is activated (bending roll force 1200-1800kN). After 5-6 passes of reversible rolling, the 100mm thick slab is thinned to a 20mm thick intermediate slab (thickness tolerance ±0.8mm).

[0058] Step 3: Precisely heat the intermediate billet.

[0059] An infrared temperature measuring device (temperature range 500-1200℃, temperature accuracy ±2℃, sampling frequency 1 time / second) monitors the surface temperature of the intermediate billet in real time. When the temperature drops below 1000℃ (the lower limit of the rollable temperature of high-temperature alloys), the intermediate billet is sent to the vertical lifting and circulating heating furnace 3 at the mill inlet via the mill inlet centering device 4 (used for three-fire reheating to ensure the stability of the temperature of the next roughing pass). It is then smoothly loaded into the station lifting device 15 by the reheating furnace charging device 11 and the flexible guiding mechanism (guide gap adjustable from 5-15mm). The annular rotating mechanism 14 (75kW geared motor, model Y2-280M-4) drives the pallet and intermediate billet to slowly rotate along the annular furnace body (rotation speed 0.5-1r / min). The zoned electric heating device automatically adjusts the heating power of each zone based on temperature data fed back from the intelligent temperature control system (heating power adjusted to 50%-70% when the temperature difference is ≤100℃; heating power adjusted to 80%-100% when the temperature difference is >100℃). The forced hot air circulation mechanism (high-temperature resistant centrifugal fan, air volume 8000m³ / h) further enhances the heating effect. 3 (800Pa air pressure) to ensure uniform temperature field within the furnace (temperature difference ≤ ±3℃). Reheat to 1030-1080℃ for 7-10 minutes, with temperature uniformity ≤ ±5℃. After reheating, the station lifting device 15 raises the furnace to the furnace outlet position, quickly moves it out of the furnace cavity via a flexible guide mechanism, and is sent back to the rolling mill by the conveyor roller 12. Simultaneously, the pallet descends to the inlet position via the potential energy recovery system (150L accumulator, 16MPa energy storage pressure), ready to receive the next intermediate billet.

[0060] Step 4: Parallel operation of multiple billets.

[0061] While the first intermediate billet is being reheated in the vertical lifting circulating heating furnace 3 at the mill inlet, the second slab is simultaneously exited from the slab walking beam furnace 2 (running speed 120m / min) and fed into the four-high reversible hot rolling mill 5 via the conveyor roller conveyor 12 (speed matched synchronously, deviation ≤0.1m / s) to start rolling. This achieves parallel rolling and reheating processes, enabling multiple billets to operate in parallel and in tandem. Once the first intermediate billet is reheated to the preset starting rolling temperature, the slab walking beam furnace 2 suspends its exit operation to match the steel output rhythm of the vertical lifting circulating heating furnace 3 at the mill inlet, achieving precise matching of the rolling rhythm. The subsequent third billet and all slabs are operated according to this logic.

[0062] Step 5: Multiple heating cycles for temperature adjustment.

[0063] High-temperature alloys have poor plasticity and require multiple rolling passes, so they need to be heated three times. The intermediate billet is sent to the vertical lifting circulating heating furnace 3 at the mill inlet for heating (heating temperature 1030-1080℃, heating time 7-10min) to ensure the temperature of the next rough rolling pass is stable and to ensure uniform rolling deformation.

[0064] Step 6: Subsequent shaping and collection.

[0065] After being reheated, the intermediate billet is sent back to the four-high reversible hot rolling mill 5 via conveyor roller 12 (running speed 80m / min). After being centered by the mill exit centering device 6, it undergoes 4-5 passes of finishing rolling (single reduction of 0.5-1mm when the finished product thickness is 3-5mm) to reach the preset finished product thickness of 5mm (thickness tolerance ±0.8mm). If further reheating is required, the intermediate billet is sent to the mill exit vertical lifting circulating heating furnace 7 via the mill exit centering device 6 for reheating. After reheating, it is sent back to the mill for further rolling. The finished sheet is sent to the mother-daughter straightener 8 via conveyor roller 12. The mother straightener performs rough straightening on the intermediate billet (straightening pressure 800-1000kN, straightening speed 30m / min). The sheet shape detection sensor at the exit of the mother straightener (detection accuracy ±0.1mm, sampling frequency 1 time / 0.1s) collects the warp and waviness sheet shape data of the intermediate billet after rough straightening in real time and transmits it to the PLC control system. The control system automatically adjusts the straightening speed, roll gap, and straightening pressure (500-700kN) of the sub-straightener based on the plate shape data, intermediate billet material, and subsequent rolling target thickness. This establishes a closed-loop control logic that feeds back coarse straightening parameters to fine straightening parameters for adaptive adjustment, thus achieving adaptive adjustment of fine straightening parameters. The finished plates are then cut to length by the fixed-length shearing unit 9 (shearing speed 30m / min, shearing accuracy ±1mm) to preset sizes. Finally, they are collected into stacks by the stacking device 10 (stack height ≤1000mm, 20-50 pieces per stack).

[0066] Step 7: Continuous production in a cycle.

[0067] All slabs are processed in a cycle according to steps 1-6 above, realizing continuous online production from slab to finished product without any offline hoisting or storage intermediate links.

[0068] A single production line can process 80,000-100,000 tons annually, with a product qualification rate exceeding 98%. Energy consumption per ton of steel is reduced by 10%-15% compared to existing processes, and production costs per ton of steel are reduced by 15%-20%. A single production line can reduce the workforce by 8-12 people. The thickness tolerance of finished steel plates is controlled within ±0.8mm, and the plate shape accuracy is ≤2mm / m. Dimensional accuracy, surface quality, and microstructure uniformity are all superior to existing processes, meeting the stringent performance requirements of special steel in aerospace, high-end equipment manufacturing, and other fields.

[0069] Example 3 like Figures 1-5 As shown, using the equipment described in Example 1, taking a small single-unit slab of 304 stainless steel (single weight ≤ 2t, thickness 80mm, width 1500mm, length 2000mm) as an example, a two-heat-compensation continuous multi-heat rolling process is carried out. The specific process flow is as follows: Step 1: Slab hoisting and precise heating.

[0070] After being centered by the pre-heating furnace centering device 1, the slab is fed into the slab walking beam furnace 2 via conveyor rollers 12 for heating. The furnace's zoned temperature control system is matched with stainless steel heating parameters: heating rate 8-12℃ / min, preheating stage power density 15-20kW / m³. 2 During the heating phase, the power density of the head heating zone increases to 25-30 kW / m². 2 During the heat preservation stage, the power density drops to 10-15 kW / m². 2 The slab is precisely heated to 1050-1100℃ and held for 160 minutes (80mm thickness), with a temperature uniformity of ≤±5℃.

[0071] Step 2: First flexible reversible rolling.

[0072] The slab exits the furnace via conveyor roller 12 (running speed 120m / min) and is fed into the four-high reversible hot rolling mill 5 via mill inlet centering device 4. The mill automatically identifies the stainless steel material and matches specific rolling parameters: rolling pressure 20000-30000kN, rolling speed 2-3m / s, pass reduction 12-15mm (first pass) gradually decreasing to 5-8mm (last pass), and bending force 800-1200kN. After 4-5 passes of reversible rolling, an intermediate slab is formed.

[0073] Step 3: Precisely heat the intermediate billet.

[0074] An infrared thermometer monitors the intermediate billet temperature in real time. When the temperature drops below 950℃ (the lower limit of the rollable temperature for stainless steel), due to the good plasticity of stainless steel and the limited number of rolling passes, a second heating process is required. The intermediate billet is fed into the vertical lifting and circulating heating furnace 7 at the mill exit via the mill exit centering device 6 for heating (ensuring the temperature meets the standards for the finishing rolling process). The heating furnace loading device 11 and flexible guiding mechanism smoothly load the billet into the station lifting device 15. The annular rotating mechanism 14 drives the pallet and intermediate billet to slowly rotate along the annular furnace body. The zoned electric heating device automatically adjusts the heating power based on feedback from the intelligent temperature control system. The forced hot air circulation mechanism ensures a uniform temperature field within the furnace (temperature difference ≤ ±3℃). The heating temperature is 980-1030℃, the heating time is 5-7 minutes, and the temperature uniformity is ≤ ±5℃.

[0075] Step 4: Parallel Operation of Multiple Billets. While the intermediate billet is being reheated in the vertical lifting circulating heating furnace 7 at the mill exit, the next slab is simultaneously exited from the slab walking beam furnace 2 and fed into the four-high reversible hot rolling mill 5 via the conveyor roller table 12. This achieves parallel rolling and reheating processes, enabling parallel operation of multiple billets. After reheating is completed, the slab walking beam furnace 2 suspends its output operation to match the steel output rhythm of the vertical lifting circulating heating furnace 7 at the mill exit.

[0076] Step 5: Subsequent shaping and collection.

[0077] After reheating, the intermediate billet is sent back to the four-high reversible hot rolling mill 5 via conveyor roller 12, and undergoes 3-4 passes of finishing rolling (single reduction of 1-2mm when the finished thickness is 5-12mm) to the preset finished thickness (thickness tolerance ±0.8mm). The finished sheet is straightened by the mother and daughter straighteners 8. The mother straightener performs rough straightening on the intermediate billet (straightening pressure 800-1500kN). The shape detection sensor at the exit of the mother straightener collects the warp and waviness shape data of the intermediate billet after rough straightening in real time. The PLC control system automatically adjusts the straightening speed, roller gap and straightening pressure (800-1000kN when the finished thickness is 5-12mm) of the daughter straightener according to the shape data, the material of the intermediate billet and the target thickness of subsequent rolling. It constructs a closed-loop control logic that feeds back the rough straightening parameters to the fine straightening parameters for adaptive adjustment, ensuring that the shape accuracy of the thin-gauge stainless steel finished sheet is ≤2mm / m. The finished boards are then cut to length by the fixed-length shearing unit 9 (shearing accuracy ±1mm), and finally collected into stacks by the stacking collection device 10.

[0078] Step 6: Continuous production in a cycle.

[0079] All slabs are produced in a cyclical manner, achieving continuous online production throughout the entire process. Finished sheet metal specifications: thickness 3mm-12mm, width 600mm-2100mm, length 1500mm-4500mm, maximum weight of a single sheet ≤2t, rolling line processing speed 50m / min-180m / min, product qualification rate ≥98%, finished sheet metal thickness tolerance controlled within ±0.8mm, and sheet shape accuracy ≤2mm / m, fully meeting the stringent performance requirements of special steel in aerospace, high-end equipment manufacturing, and other fields.

[0080] This process can be widely applied to the continuous multi-fire rolling production of various types of small single-weight special steels, such as high-temperature alloys, corrosion-resistant alloys, ultra-high-strength steels, stainless steels, and tool steels, filling the technological gap in the online continuous multi-fire rolling of small single-weight thin-specification special steels.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A continuous multi-fire rolling production equipment for small-weight, thin-gauge special steel plates, characterized in that, It includes a slab heating furnace, a four-roll reversible hot rolling mill, a vertical lifting circulating heating furnace, a hot straightener, a fixed-length shearing unit, a stack collection device, a conveyor roller table, and a signal control system; The output end of the slab heating furnace is connected to the input end of the four-high reversible hot rolling mill via a conveyor roller conveyor, which conveys the heated slab to the rolling mill. There are two vertical lifting circulating heating furnaces, which are respectively set on the side of the input and output roller table of the four-roll reversible hot rolling mill. The two vertical lifting circulating heating furnaces are respectively connected to the input and output roller table of the four-roll reversible hot rolling mill through the conveying roller table. They are used to receive intermediate billets online for reheating and send the reheated intermediate billets back to the four-roll reversible hot rolling mill for further rolling. The output end of the four-roll reversible hot rolling mill is connected in sequence to the hot straightening machine, the fixed-length shearing unit and the stack collection device via conveyor rollers; the equipment is connected in series via conveyor rollers to form a closed-loop continuous production line, so that the intermediate billet can be rolled online continuously with multiple fires without offline hoisting and storage. The signal control system is connected to the slab heating furnace, the four-roll reversible hot rolling mill, the vertical lifting circulating heating furnace, and the conveyor roller conveyor, and is used to coordinate the signal interaction and collaborative linkage between the various devices.

2. The equipment according to claim 1, characterized in that, The vertical lifting circulating heating furnace includes a vertical ring furnace body, a ring rotating mechanism, a workstation lifting device, a zoned electric heating device, and an intelligent temperature control system. The vertical annular furnace body adopts a closed annular structure, with multiple independent heating stations evenly arranged around the circumference of the furnace body. The furnace body has a reserved inlet and outlet, which are respectively connected to the conveyor rollers. The annular rotating mechanism includes a geared motor, an annular hub, and spokes. The geared motor is connected to the annular hub via a coupling. Multiple station lifting devices for supporting intermediate blanks are distributed circumferentially on the annular hub. Each station lifting device is connected to the annular hub via spokes. The geared motor drives the annular hub to rotate at a constant speed, which in turn drives the lifting devices at each station to rotate in a circular motion within the vertical annular furnace, so that the intermediate billet can be uniformly heated during the annular motion. The partitioned electric heating device is embedded in the insulation layer of the inner wall of the vertical annular furnace, forming multiple heating partitions corresponding to the heat replenishment stations distributed along the circumference. The intelligent temperature control system is connected to the zoned electric heating device and the ring rotation mechanism via signals, and is used to automatically adjust the heating power of each zone and the ring rotation speed based on temperature feedback.

3. The equipment according to claim 2, characterized in that, The pallet of the workstation lifting device is made of heat-resistant steel, and the surface of the pallet is covered with a high-temperature resistant ceramic anti-scratch coating. Flexible baffles are set on the edges of the pallet to prevent surface scratches and slippage of the intermediate billet during the cyclic rotation and reheating process. Each heating zone of the partitioned electric heating device is equipped with an electric heating element, which, together with the forced hot air circulation mechanism installed on the top of the furnace body, achieves uniform temperature distribution inside the furnace and controls the temperature difference between different areas inside the furnace to ≤±3℃. The vertical annular furnace body is equipped with a flexible guiding mechanism and a sealing structure at the inlet and outlet, so that the working temperature inside the furnace is stable at 500℃-980℃, and the temperature compensation and control accuracy is ≤±5℃. The ring-shaped rotating mechanism is equipped with an energy accumulator, which is connected to a geared motor through a hydraulic pipeline. It is used to recover the gravitational potential energy on the lowering side of the workstation lifting device and circulate it for the workstation lifting operation on the upper side.

4. The equipment according to claim 1, characterized in that, The roller surface of the conveyor is treated with a wear-resistant and scratch-resistant coating. The outside of the roller is equipped with a heat insulation protective layer and an intermittent heating device to control the temperature drop during the transfer of the plate within 20℃ / min. The roller running speed is 1m / s-3m / s and has stepless speed regulation.

5. The equipment according to claim 1, characterized in that, The hot straightener adopts a front and rear mother-daughter straightener tandem arrangement structure, and is arranged coaxially along the center line of the conveyor roller table. The mother straightener is a large-diameter straightener, located at the front of the tandem, and is used for rough straightening of thicker intermediate billets; the daughter straightener is a small-diameter straightener, located at the rear of the tandem, and is used for fine straightening of thinner finished sheets. The mother straightener and the daughter straightener are fixedly connected by a rigid bracket and a transition roller table is set to achieve seamless connection. The mother and daughter straighteners are equipped with a collaborative linkage control system. A plate shape detection sensor is installed at the exit of the mother straightener to collect the warp and waviness plate shape data of the intermediate billet after rough straightening in real time and transmit the data to the signal control system. The signal control system automatically adjusts the straightening speed, roller gap and straightening pressure of the daughter straightener according to the plate shape data, the material of the intermediate billet and the target thickness of subsequent rolling. It constructs a closed-loop control logic that feeds back the rough straightening parameters to the fine straightening parameters for adaptive adjustment, so as to achieve precise matching of rough straightening and fine straightening parameters.

6. The equipment according to claim 1, characterized in that, The signal control system uses a PLC controller to achieve bidirectional signal interaction with the slab heating furnace, the four-roll reversible hot rolling mill, the vertical lifting circulating heating furnace, and the conveyor rollers. The four-roll reversible hot rolling mill collects rolling load, roll gap opening and rolling speed parameters in real time, sends steel demand signals to the slab heating furnace and receives slab ready signals, receives intermediate billet reheating completion signals to the vertical lifting circulating heating furnace, and sends speed matching signals to the conveyor roller table to ensure seamless connection of each process.

7. The equipment according to claim 1, characterized in that, The slab heating furnace adopts a side-in, side-out arrangement, and the furnace opening adopts a single-door sealed structure. The furnace is equipped with a zoned precision temperature control system, which is divided into multiple heating zones along the length of the furnace. Each heating zone is equipped with multiple sets of electric heating elements, and the temperature control accuracy is ≤±3℃. The atmosphere inside the furnace is controlled by a slight positive pressure. When the intermediate billet is discharged from the vertical lifting circulating heating furnace after being reheated, the slab heating furnace suspends the discharge operation to match the steel discharge rhythm of the vertical lifting circulating heating furnace and achieve precise matching of the rolling rhythm.

8. A continuous multi-fire rolling process for producing small-weight, thin-gauge special steel plates, characterized in that, The equipment described in any one of claims 1 to 7 is used for continuous multi-fire rolling production of various types of small-weight special steels, including high-temperature alloys, corrosion-resistant alloys, ultra-high-strength steels, stainless steels, or tool steels. The production process employs a multi-slab parallel linkage and multi-fire online continuous rolling method, specifically including the following steps: After being heated to the preset target rolling temperature in a slab walking beam furnace, the small single-weight special steel slab is sent to a four-roll reversible hot rolling mill for reversible rolling to form an intermediate slab. When the temperature of the intermediate billet drops below the rollable temperature range, the intermediate billet is transferred online via conveyor rollers to a vertical lifting circulating heating furnace for reheating. While the intermediate billet is being reheated in the vertical lifting circulating heating furnace, the next slab is taken out of the slab heating furnace and sent to a four-high reversible hot rolling mill for rolling, realizing the parallel operation of rolling and reheating processes, and the parallel linkage operation of multiple billets. After being reheated to the preset rolling temperature, the intermediate billet is sent back to the four-high reversible hot rolling mill via conveyor rollers to continue rolling, repeating the rolling and reheating steps until the preset finished thickness is reached. The finished boards are straightened by a hot straightening machine, cut to length by a fixed-length shearing unit, and finally collected into stacks by a stacking and collecting unit, realizing online continuous production from board blank to finished product.

9. The continuous multi-fire rolling production process for small-weight, thin-gauge special steel plates according to claim 8, characterized in that, To address the multi-pass rolling requirements of different types of special steel, a differentiated arrangement of the heating furnace is adopted: intermediate billets requiring two-pass heating are sent to the vertical lifting and circulating heating furnace following the four-roll reversible hot rolling mill for heating to ensure that the temperature of the finishing rolling process meets the standards; intermediate billets requiring three-pass heating are sent to the vertical lifting and circulating heating furnace preceding the four-roll reversible hot rolling mill for heating to ensure that the temperature of the next roughing rolling pass is stable.

10. The continuous multi-fire rolling production process for small-weight, thin-gauge special steel plates according to claim 8, characterized in that, The slab heating furnace is configured with differentiated heating parameters based on the slab material: the heating rate for high-temperature alloys is 5-8℃ / min, and the heating rate for stainless steel is 8-12℃ / min; the heating power density is dynamically adjusted according to the heating stage: the power density is controlled at 15-20kW / m³ during the preheating stage. 2 During the heating phase, the power density increases to 25-30 kW / m³. 2 During the heat preservation stage, the power density drops to 10-15 kW / m². 2 .

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