A method for controlling forced air cooling of a hot-rolled aluminum coil and a cooling device

Abstract

The application relates to the technical field of hot-rolled aluminum coil cooling, in particular to a forced air cooling control method for hot-rolled aluminum coils and a cooling device. The method comprises the following steps: delivering a pulsating air flow to the end of a hot-rolled aluminum coil; before reaching the end of the hot-rolled aluminum coil, the pulsating air flow is divided into two parts, one part of the air flow enters the inner hole of the hot-rolled aluminum coil, flows in the axial direction and sweeps the inner surface for cooling, and the other part of the air flow forms a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil and cools the outer surface; detecting the temperature of the outer surface of the hot-rolled aluminum coil, and adjusting at least one of the pulsating frequency, the duty cycle and the air supply amount in the high-flow stage of the pulsating air flow according to the temperature of the outer surface and the temperature change trend. The application can simultaneously carry out convective heat exchange and cooling on the inner surface and the outer surface of the hot-rolled aluminum coil, further strengthens wall heat exchange with the help of air flow pulsation disturbance, and effectively improves the cooling efficiency of the hot-rolled aluminum coil and the uniformity of the temperature field of the hot-rolled aluminum coil after cooling.

Description

Technical Field

[0001] This application relates to the field of hot-rolled aluminum coil cooling technology, specifically to a forced air cooling control method and cooling device for hot-rolled aluminum coils. Background Technology

[0002] With the rapid development of high-end manufacturing industries such as new energy vehicles, the demand for lightweight products is becoming increasingly urgent, driving a steady increase in the market demand for aluminum alloy materials and leading to a year-on-year increase in the number of aluminum hot-rolling production lines put into operation. When aluminum coils are finished rolling on a hot rolling mill, their temperature is typically above 300℃. If they are directly introduced into subsequent production processes under these conditions, it will not only be difficult to guarantee the processing quality of the finished aluminum coils, but it also does not meet the requirements of standardized production processes. To meet the temperature requirements of subsequent cold rolling, straightening, and edge trimming processes, the hot-rolled aluminum coils must be allowed to cool statically in the coil storage area until the temperature drops to room temperature before proceeding to the next process.

[0003] Traditional cooling of hot-rolled aluminum coils primarily relies on natural cooling, which depends on natural air convection to remove the coil's own heat. This method is slow, sometimes taking several days to reach the target temperature in summer. This cooling approach not only occupies significant storage space and results in low site utilization, but also leads to long-term capital tied up in work-in-process inventory and low production turnover efficiency. To improve cooling efficiency and shorten the cooling cycle, forced air cooling has become widely adopted in the industry to replace traditional natural cooling. For example, the technical solutions disclosed in CN119566078A and CN119702723A both employ a cooling method that forces airflow radially from below the aluminum coil towards its outer surface, achieving rapid cooling of the hot-rolled aluminum coil.

[0004] However, existing forced air cooling methods still have the following shortcomings: First, the current air supply only acts on the outer surface or end face of the aluminum coil. Heat must first be conducted from the inside of the aluminum coil to the outer surface before it can be carried away by the airflow. Due to the limitations of the radial and interlayer thermal resistance of the aluminum coil, the internal heat conduction rate is slow. The mismatch between forced convection on the surface and slow internal heat conduction results in limited improvement in overall cooling efficiency, and the cooling uniformity of different parts of the aluminum coil is poor. Second, existing air cooling methods can only achieve simple start-stop or speed control of the fan, and cannot precisely control the cooling process according to process requirements, which easily leads to problems such as uneven cooling, overcooling, or untimely cooling. Summary of the Invention

[0005] The purpose of this application is to provide a forced air cooling control method and cooling device for hot-rolled aluminum coils, which solves the problems of limited improvement in overall cooling efficiency and poor cooling uniformity of existing forced air cooling methods.

[0006] The technical solution adopted by this application to solve its technical problem is: Firstly, a forced air cooling control method for hot-rolled aluminum coils is provided, comprising: A pulsating airflow is delivered to the end of the hot-rolled aluminum coil in a direction parallel to the axial direction of the hot-rolled aluminum coil. The pulsating airflow has a periodically alternating high flow rate phase and a low flow rate phase, and the air volume delivered in the high flow rate phase is greater than the air volume delivered in the low flow rate phase. The pulsating airflow is divided into two parts before reaching the end of the hot-rolled aluminum coil. One part of the airflow enters the inner hole of the hot-rolled aluminum coil, flows axially, and sweeps and cools the inner surface. The other part of the airflow forms a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil and cools the outer surface. The outer surface temperature of the hot-rolled aluminum coil is detected, and at least one of the following is adjusted according to the outer surface temperature and the temperature change trend: pulsation frequency, duty cycle, and high flow rate air volume of the pulsating airflow.

[0007] Furthermore, the pulsation frequency, duty cycle, and high-flow-rate airflow of the pulsating airflow are adjusted based on a pre-established cooling rate control model, which is as follows:

[0008] in, The cooling rate of hot-rolled aluminum coil, in units of... ; The effective heat exchange area of ​​hot-rolled aluminum coil, in units of... ; The mass of hot-rolled aluminum coil, in units of... ; Specific heat capacity of hot-rolled aluminum coil material, unit: ; The equivalent convective heat transfer coefficient is expressed in units of 1000 ppm. ; The equivalent average temperature of hot-rolled aluminum coils, in units of... ; The temperature of the cooling air is expressed in units of _____. ; The surface emissivity of hot-rolled aluminum coil; This is the Stefan-Boltzmann constant, with units of 1. ; The duty cycle of the pulsating airflow; The convective heat transfer coefficient during the high flow rate stage is expressed in units of... ; The convective heat transfer coefficient is given at low flow rates, and the unit is _____. ; The amplitude coefficient for pulsating heat transfer enhancement; The heat transfer enhancement index is the pulsating heat transfer enhancement index. The pulsation frequency of the pulsating airflow, measured in units of _____. ; The hydraulic diameter of the characteristic flow channel, in units of _____. ; The effective flow area of ​​the channel before the pulsating airflow is split into two parts, in units of ; The high-flow-rate supply air volume before the pulsating airflow is split into two parts, measured in units of... .

[0009] Furthermore, the amplitude coefficient of the pulsating heat transfer enhancement With the aforementioned pulsating heat transfer enhancement index The calibration is performed in the following manner: Under the condition that the specifications of the hot-rolled aluminum coil, ambient temperature, and flow channel structure parameters remain unchanged, cooling tests or flow field heat transfer coupling simulations are conducted by changing the pulsation frequency, duty cycle, and air volume during the high-flow stage of the pulsating airflow, respectively, to obtain the curves of the outer surface temperature of the hot-rolled aluminum coil over time under each working condition; the equivalent convective heat transfer coefficient for each working condition is calculated based on the temperature drop rate of the hot-rolled aluminum coil. The equivalent convective heat transfer coefficient was fitted using the nonlinear least squares method. With Strauhall The relationship between them yields the amplitude coefficient of pulsating heat transfer enhancement. With the pulsating heat transfer enhancement index .

[0010] Furthermore, the entire process of cooling the hot-rolled aluminum coil from the post-rolling temperature to the target temperature is divided into three stages: initial cooling, intermediate cooling, and final cooling. The cooling rate in the initial cooling stage is greater than the cooling rate in the intermediate cooling stage, and the cooling rate in the intermediate cooling stage is greater than the cooling rate in the final cooling stage.

[0011] Furthermore, the initial cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is higher than 200°C, the middle cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is between 100°C and 200°C, and the final cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is lower than 100°C.

[0012] Furthermore, in each cooling stage, the actual cooling rate of the hot-rolled aluminum coil is calculated based on the outer surface temperature of the hot-rolled aluminum coil, and the actual cooling rate of the hot-rolled aluminum coil is compared with the target cooling rate to obtain the rate deviation. When the rate deviation is within the preset allowable deviation range, the pulsation frequency, duty cycle and high flow rate of the pulsating airflow are kept constant. When the rate deviation exceeds the preset allowable deviation range and the actual cooling rate is lower than the target cooling rate, increase the duty cycle and / or the air volume during the high flow stage. When the rate deviation exceeds the preset allowable deviation range and the actual cooling rate is higher than the target cooling rate, the duty cycle and / or the air volume during the high flow stage are reduced.

[0013] Secondly, a hot-rolled aluminum coil cooling device is provided to implement the aforementioned forced air cooling control method for hot-rolled aluminum coils. It includes an air-cooled box and an air supply unit. The air-cooled box is enclosed to form an air-cooled chamber that extends horizontally and is open at both ends. The air-cooled chamber is used to accommodate hot-rolled aluminum coils. The air supply unit includes a pulsed air inlet pipe, a spiral air guide shroud, a central guide pipe, and spiral fins. The spiral air guide shroud is a horizontally arranged hollow cone structure. Its large end is connected to one end of the air-cooled chamber, and its small end is connected to the coaxially arranged pulsed air inlet pipe. The pulsed air inlet pipe is used to transport pulsed airflow. The central guide tube is coaxially disposed inside the spiral air guide shroud, and a plurality of spiral ribs are evenly distributed and connected between the central guide tube and the spiral air guide shroud. Each spiral rib extends spirally along the axial direction of the central guide tube. The inner cavity of the central guide pipe connects the pulsating air inlet pipe and the air-cooling chamber to form an inner air-cooling channel, which is used to allow a portion of the pulsating airflow to flow out and flow axially along the inner hole of the hot-rolled aluminum coil. The annular space between the central guide pipe and the spiral air guide shroud connects the pulsating air inlet pipe and the air-cooling chamber, forming an external air-cooling channel for another part of the pulsating airflow to flow out and form a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil.

[0014] Furthermore, the air supply unit includes multiple units, which are located on the same side of the air-cooled chamber and arranged side by side along a horizontal direction perpendicular to the air-cooled chamber. The large end of the spiral air guide shroud of each air supply unit is connected to the air-cooled chamber.

[0015] Furthermore, the cross-sectional area of ​​the inner hole of the central guide pipe gradually decreases along the direction from the pulsating air inlet pipe to the air-cooled chamber, and the relationship of the change in cross-sectional area is as follows:

[0016] in, The cross-sectional area at the current location, in units of ; This is the cross-sectional area of ​​the entrance end, in units of... ; This refers to the cross-sectional area of ​​the outlet end, in units of... ; The axial length of the central guide tube, in units of... ; The distance between the current location and the entrance, in units of ; The flow channel gradient index.

[0017] Furthermore, the air-cooled box has an open bottom structure, and the two side walls of the bottom of the air-cooled box are slidably connected to the support platform. The support platform is provided with a cooling station and a loading and unloading station in sequence along the extension direction of the air-cooled chamber. The cooling station is provided with an aluminum coil base for supporting the hot-rolled aluminum coil. The air-cooled box can move back and forth between the cooling station and the loading and unloading station.

[0018] The beneficial effects of this application are: 1. This application delivers a pulsating airflow to the end of a hot-rolled aluminum coil. Before reaching the end, the pulsating airflow splits into two parts. One part enters the inner hole of the hot-rolled aluminum coil and sweeps axially to cool the inner surface, while the other part forms a spiral wall-attached flow to cool the outer surface. This allows for simultaneous convective heat transfer cooling of both the inner and outer surfaces of the hot-rolled aluminum coil, directly removing heat accumulated at the coil core. The spiral wall-attached flow also disrupts the airflow boundary layer on the outer surface, further enhancing heat transfer. Furthermore, both sub-airflows inherit the pulsating characteristics of the upstream pulsating airflow, further enhancing wall heat transfer through airflow pulsation disturbance. Compared to traditional methods that only radially cool the outer surface of the aluminum coil, this application effectively improves the cooling efficiency of the hot-rolled aluminum coil, reduces the radial and circumferential temperature difference, improves the uniformity of the temperature field after cooling, and reduces the risk of inconsistent aluminum coil material properties caused by excessive local temperature differences.

[0019] 2. This application obtains a quantitative mapping relationship between the cooling rate of hot-rolled aluminum coils and the pulsating airflow parameters by pre-establishing a cooling rate control model; and completes the calibration of the pulsating heat transfer enhancement amplitude coefficient and the pulsating heat transfer enhancement index by cooling experiments or flow field heat transfer coupling simulation combined with nonlinear least squares method; thereby, the target cooling rate can be substituted into the cooling rate control model to solve in reverse to obtain the required pulsating frequency, duty cycle, and air volume in the high flow stage, realizing the quantitative calculation of the cooling process, providing a reliable calculation basis for the precise adjustment of pulsating airflow parameters, reducing the influence of human experience factors on the cooling process, and reducing the risk of overcooling or undercooling in the cooling process. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the forced air cooling control method for hot-rolled aluminum coils provided in the embodiments of this application; Figure 2 This is a perspective view of the hot-rolled aluminum coil cooling device provided in the embodiments of this application; Figure 3 This is a perspective view of the hot-rolled aluminum coil cooling device provided in the embodiments of this application; Figure 4 This is a 3D view of the air supply unit; Figure 5 This is a three-dimensional view of the air supply unit from another perspective; Figure 6 This is an end view of the air supply unit; Figure 7 This is a schematic diagram showing the change in the cross-sectional area of ​​the inner hole of the central guide tube; Figure label: 1-Air-cooled box; 11-Air-cooled chamber; 12-Heat dissipation window; 2-Air supply unit; 21-Pulsating air inlet duct; 22-Spiral air guide shroud; 23-Central air guide duct; 24-Spiral fins; 25-Inner air cooling channel; 26-Outer air cooling channel; 3-Bearing platform; 31-Cooling station; 32-Loading and unloading station; 33-Railway; 4-Aluminum coil base; 5-Hot-rolled aluminum coil. Detailed Implementation

[0022] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0024] In the description of this application, the terms "upper," "lower," "left," "right," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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, they should not be construed as limitations on this application. Unless otherwise specified, the above-mentioned orientational descriptions can be flexibly set in actual application, provided that the relative positional relationships shown in the accompanying drawings are satisfied.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] See Figure 1 This application provides a forced air cooling control method for hot-rolled aluminum coils, comprising the following steps: S1. A pulsating airflow is delivered to the end of the hot-rolled aluminum coil in a direction parallel to the axial direction of the hot-rolled aluminum coil. The pulsating airflow has a periodically alternating high flow rate phase and a low flow rate phase, and the air volume delivered in the high flow rate phase is greater than the air volume delivered in the low flow rate phase.

[0027] Specifically, pulsed airflow is an airflow whose delivery volume alternates periodically between high and low flow rates according to a set cycle. Within one pulse cycle, the period with higher airflow output is the high flow rate phase, and the period with lower airflow output is the low flow rate phase. Pulsed airflow can generate periodic impact and peeling effects on the surface of hot-rolled aluminum coils, forming periodic disturbances and continuously damaging the thermal boundary layer of the cooled surface. During the intermittent phases of pulsed airflow, it reduces the ineffective energy consumption caused by continuous high-speed airflow. At the same time, it promotes near-wall fluid renewal through periodic pressure changes, reduces the adverse effects of continuous thermal boundary layer thickening on the heat transfer process, and enhances convective heat transfer between the airflow and the surface of the aluminum coil, thereby improving convective heat transfer efficiency. In this embodiment, the delivery direction of the pulsed airflow is coaxial with the hot-rolled aluminum coil, ensuring that the airflow can be aligned with the end of the aluminum coil, and a portion of the airflow can smoothly enter the inner hole in the middle of the aluminum coil.

[0028] S2. The pulsating airflow is divided into two parts before reaching the end of the hot-rolled aluminum coil. One part of the airflow enters the inner hole of the hot-rolled aluminum coil, flows axially, and sweeps and cools the inner surface. The other part of the airflow forms a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil and cools the outer surface.

[0029] Specifically, the pulsating airflow is split into two parts before it even contacts the end of the hot-rolled aluminum coil. One part of the airflow flows into the inner hole of the hot-rolled aluminum coil and continues to flow along the axial direction of the inner hole to sweep and scour the inner wall of the aluminum coil, directly carrying out convective heat transfer and cooling on the inner surface of the aluminum coil, removing the heat accumulated in the core part of the aluminum coil, and improving the heat transfer capacity of the inner hole area of ​​the hot-rolled aluminum coil.

[0030] Another portion of the airflow flows along the outer surface of the aluminum coil, forming a spiral wall-attached flow. This spiral wall-attached flow is an airflow pattern that adheres to the outer surface of the hot-rolled aluminum coil and undergoes a spiraling motion. This airflow can disrupt the flow boundary layer on the outer surface of the aluminum coil, reduce boundary layer thermal resistance, and enhance the convective heat transfer effect on the outer surface. Because the spiral wall-attached flow moves along the outer circumference while flowing along the axial direction of the hot-rolled aluminum coil, it can extend the effective contact path between the airflow and the outer surface of the hot-rolled aluminum coil, expand the coverage area of ​​the airflow on the outer circumferential surface, reduce local flow deviation and low-speed regions, and further improve the convective heat transfer efficiency.

[0031] It should be noted that the two sub-flows obtained by the split inherit the flow characteristics of the upstream pulsating airflow. The pulsation frequency and duty cycle of the two sub-flows are consistent with the total pulsating airflow before the split, and the periodic switching between the high flow rate stage and the low flow rate stage is completed synchronously. That is, the internal hole cooling airflow and the external surface cooling airflow are both pulsating airflows.

[0032] S3. Detect the outer surface temperature of the hot-rolled aluminum coil, and adjust at least one of the following according to the outer surface temperature and temperature change trend: pulsation frequency of the pulsating airflow, duty cycle, and air volume during the high flow stage.

[0033] Specifically, temperature detection can be achieved using an infrared thermometer. The thermometer is positioned facing the outer surface of the hot-rolled aluminum coil to collect the temperature signal of the outer surface of the aluminum coil in real time. Based on the multiple sets of outer surface temperature data collected continuously, the real-time temperature value of the outer surface of the hot-rolled aluminum coil can be obtained, and the temperature change trend can be calculated by the temperature difference between the previous and next times. The temperature change trend is used to characterize the current actual cooling rate of the hot-rolled aluminum coil.

[0034] By real-time monitoring of the outer surface temperature of hot-rolled aluminum coils and calculating the temperature change trend, the actual cooling state of the hot-rolled aluminum coils can be comprehensively judged. This cooling state includes the current temperature level of the aluminum coil and the actual cooling rate. When the actual cooling state of the hot-rolled aluminum coil does not meet the preset cooling requirements, at least one of the following can be adjusted: the pulsation frequency, duty cycle, and high-flow-rate air volume of the pulsating airflow. This changes the convective heat transfer enhancement capability of the pulsating airflow, matches the real-time heat dissipation needs of the hot-rolled aluminum coil, and allows the cooling process of the hot-rolled aluminum coil to return to the preset cooling state.

[0035] The pulse frequency is the frequency at which the pulsed airflow completes one cycle; the duty cycle is the proportion of time occupied by the high-flow phase within a single pulse cycle; and the high-flow phase air volume is the air volume corresponding to the high-flow phase before the pulsed airflow splits into two sub-airflows. In this embodiment, any one of the pulse frequency, duty cycle, and high-flow phase air volume can be adjusted, or two or three can be adjusted simultaneously. The control system flexibly selects the adjustment target according to the real-time heat dissipation requirements of the hot-rolled aluminum coil.

[0036] Accordingly, this application delivers a pulsating airflow to the end of the hot-rolled aluminum coil. Before reaching the end of the hot-rolled aluminum coil, the pulsating airflow splits into two parts. One part of the airflow enters the inner hole of the hot-rolled aluminum coil and sweeps axially to cool the inner surface of the hot-rolled aluminum coil, while the other part of the airflow forms a spiral wall-attached flow to cool the outer surface of the hot-rolled aluminum coil. This allows for simultaneous convective heat transfer cooling of both the inner and outer surfaces of the hot-rolled aluminum coil, directly removing the heat accumulated at the core of the aluminum coil. The spiral wall-attached flow also disrupts the airflow boundary layer on the outer surface of the aluminum coil, further enhancing heat transfer on the outer surface. Furthermore, both sub-airflows after splitting inherit the pulsating characteristics of the upstream pulsating airflow, further enhancing wall heat transfer through airflow pulsation disturbance. Compared to the traditional method of radial airflow cooling only on the outer surface of the aluminum coil, this application can effectively improve the cooling efficiency of the hot-rolled aluminum coil, reduce the radial and circumferential temperature difference of the aluminum coil, improve the uniformity of the temperature field after cooling, and reduce the risk of inconsistent aluminum coil material properties caused by excessive local temperature differences.

[0037] In some embodiments, the pulsation frequency, duty cycle, and air volume during the high-flow stage of the pulsating airflow are adjusted based on a pre-established cooling rate control model. This cooling rate control model is based on the energy conservation principle of the hot-rolled aluminum coil cooling process, while also considering convective heat transfer, radiative heat transfer, and the heat transfer enhancement effect brought about by the pulsating flow. It establishes a quantitative mapping relationship between the cooling rate of the hot-rolled aluminum coil and various control parameters of the pulsating airflow, providing a calculation basis for quantitatively solving the pulsating airflow control parameters.

[0038] Specifically, under forced air cooling conditions, the rate of decrease in the internal energy of a hot-rolled aluminum coil is equal to the sum of the convective heat dissipation rate and the radiative heat dissipation rate on the surface of the coil. The transient energy balance equation for the cooling process of a hot-rolled aluminum coil is:

[0039] in, The mass of hot-rolled aluminum coil, in units of... ; Specific heat capacity of hot-rolled aluminum coil material, unit: ; This represents the rate of change of temperature of hot-rolled aluminum coil over time, expressed in units of... ; The effective heat exchange area of ​​hot-rolled aluminum coil, in units of... ; The equivalent convective heat transfer coefficient is expressed in units of 1000 ppm. ; The equivalent average temperature of hot-rolled aluminum coils, in units of... ; The temperature of the cooling air is expressed in units of _____. ; The surface emissivity of hot-rolled aluminum coil; This is the Stefan-Boltzmann constant, with units of 1. Its value is .

[0040] The formula for calculating the effective heat exchange area of ​​hot-rolled aluminum coil is:

[0041] in, The outer diameter of the hot-rolled aluminum coil, in units of... ; This refers to the inner diameter of a hot-rolled aluminum coil, in units of... ; The axial width of the hot-rolled aluminum coil is expressed in units of... .

[0042] The equivalent average temperature of hot-rolled aluminum coil is not the directly measured outer surface temperature. Instead, the outer surface temperature is first acquired using a temperature detection device. Then, based on a pre-established temperature correction relationship, the measured outer surface temperature is corrected and converted to obtain the equivalent average temperature that characterizes the overall thermal state of the aluminum coil. This temperature correction relationship comprehensively considers factors affecting the temperature difference between the inside and outside of the aluminum coil, such as coil thickness, number of winding layers, thermal conductivity, and current cooling rate. It reflects the mapping relationship between the outer surface temperature and the average internal temperature of the aluminum coil, thus compensating for the inability to directly obtain the overall average temperature of the aluminum coil by only detecting the outer surface temperature.

[0043] The cooling rate of hot-rolled aluminum coil is defined as:

[0044] in, The cooling rate of hot-rolled aluminum coil, in units of... The negative sign indicates that the temperature of the aluminum coil decreases over time.

[0045] Substituting the cooling rate formula into the transient energy balance equation, we obtain the following formula:

[0046] This formula characterizes the relationship between the cooling rate of hot-rolled aluminum coil and the heat transfer conditions, as well as the physical parameters of the hot-rolled aluminum coil.

[0047] The cooling airflow in this application is a pulsed airflow, with one pulse cycle divided into a high-flow stage and a low-flow stage; the calculation formulas for the pulse cycle, the duration of the high-flow stage, and the duration of the low-flow stage are as follows:

[0048] in, The pulse period is measured in units of 1. ; The pulsation frequency of the pulsating airflow, measured in units of _____. The setting is determined by the control signal from the fan frequency conversion module or the electrically controlled pulse valve; The duty cycle of the pulsating airflow is dimensionless and ranges from 0 to 1. It is determined by the ratio of the duration of the high-flow phase in the pulsating control signal to the pulsating period. The duration of the high-flow phase within one pulse cycle, measured in units of... ; The duration of the low-flow phase within one pulse cycle, measured in units of... .

[0049] Without considering the intensifying effect of pulsating flow disturbances, the formula for calculating the average convective heat transfer coefficient over one pulsation cycle is:

[0050] Substituting the formulas for calculating the pulsation period, the duration of the high-flow phase, and the duration of the low-flow phase into the above formula, we get:

[0051] in, The average convective heat transfer coefficient over one pulsation cycle, in units of... ; The convective heat transfer coefficient during the high flow rate stage is expressed in units of... ; The convective heat transfer coefficient is given at low flow rates, and the unit is _____. .

[0052] In addition to the time-averaged heat transfer contribution from the alternation of high and low flow rates, the periodic disturbance of the pulsating airflow disrupts the wall boundary layer, causing periodic disturbances, thinning, and reformation of the flow boundary layer on the surface of the hot-rolled aluminum coil, thus producing an additional heat transfer enhancement effect. This enhancement effect is achieved by introducing a pulsating heat transfer enhancement correction coefficient. At the same time, combined with the dimensionless Strauhal number Introducing a pulsed heat transfer enhancement amplitude coefficient Pulsating heat transfer enhancement index The enhancement ratio is characterized together to obtain the equivalent convective heat transfer coefficient.

[0053] The formula for calculating the Strauhall number is:

[0054] in, , is the Strauhal number, which is dimensionless and used to characterize the unsteady characteristics of cooling airflow; The pulsation frequency of the pulsating airflow, measured in units of _____. ; The hydraulic diameter of the characteristic flow channel, in units of _____. The equivalent length used to characterize the cross-sectional dimensions of the characteristic flow channel of the cooling airflow; The wind speed during the high-flow phase of pulsating airflow, measured in units of... ; The effective flow area of ​​the channel before the pulsating airflow is split into two parts, in units of ; This is the wetted perimeter of the actual cross-section in contact with the airflow, in units of... ; The high-flow-rate supply air volume before the pulsating airflow is split into two parts, measured in units of... .

[0055] The pulsating heat transfer enhancement correction coefficient is used as a global correction term to compensate for the system deviation between the model and the actual operating conditions caused by airflow leakage, flow channel loss, assembly deviation, and installation gap. This coefficient is an experimental calibration coefficient and does not change the basic heat transfer physical relationship.

[0056] The formula for calculating the correction factor for pulsating heat transfer enhancement is:

[0057] This formula belongs to the empirical-semi-empirical correction form, used to fit the additional heat transfer enhancement effect brought about by fluctuating flow. Among them, This is a dimensionless correction factor for heat transfer enhancement of pulsating airflow relative to periodic average flow. The amplitude coefficient for enhanced pulsating heat transfer is dimensionless. The pulsating heat transfer enhancement index is dimensionless. , None of these results are obtained through theoretical analysis; they require fitting and calibration based on experience or simulation data.

[0058] The formula for calculating the equivalent convective heat transfer coefficient is:

[0059] By combining the above formulas, we can obtain the cooling rate control model for hot-rolled aluminum coils:

[0060] Accordingly, this application obtains a quantitative mapping relationship between the cooling rate of hot-rolled aluminum coil and the pulsating airflow parameters by pre-establishing a cooling rate control model. Thus, the target cooling rate can be substituted into the cooling rate control model to solve in reverse the required pulsating frequency, duty cycle, and air volume during the high flow stage, thereby realizing the quantitative calculation of the cooling process. This provides a reliable calculation basis for the precise adjustment of pulsating airflow parameters, reduces the influence of human experience factors on the cooling process, and reduces the risk of overcooling or undercooling during the cooling process.

[0061] In some embodiments, the amplitude coefficient of pulsating heat transfer enhancement With the pulsating heat transfer enhancement index The calibration is performed in the following manner: Under the condition that the specifications of hot-rolled aluminum coil, ambient temperature, and flow channel structure parameters remain unchanged, multiple cooling tests or multiple flow field-heat transfer coupled simulation calculations are carried out by changing the pulsation frequency, duty cycle, and air volume during the high-flow stage of the pulsating airflow. Each test or simulation corresponds to a different combination of pulsating airflow parameters. During the operation of each set of working conditions, the curve of the outer surface temperature of the hot-rolled aluminum coil changing with time is continuously collected or simulated and output. Based on the curve of the outer surface temperature of the hot-rolled aluminum coil changing with time under each set of working conditions, the temperature drop rate of the hot-rolled aluminum coil is calculated. The equivalent convective heat transfer coefficient of each working condition is calculated back based on the temperature drop rate of the hot-rolled aluminum coil. After obtaining multiple sets of equivalent convective heat transfer coefficients With Strauhall After obtaining the sample data, the equivalent convective heat transfer coefficient was calculated using the nonlinear least squares method. With Strauhall The relationship between the two factors was fitted to obtain the amplitude coefficient of the pulsating heat transfer enhancement. With the pulsating heat transfer enhancement index .

[0062] When the amplitude coefficient of pulsating heat transfer enhancement With the pulsating heat transfer enhancement index After calibration, the obtained pulsating heat transfer enhancement amplitude coefficient will be... With the pulsating heat transfer enhancement index The data is stored in the control system and can be directly called upon when calculating the cooling rate. When changing to different specifications of hot-rolled aluminum coils or modifying the flow channel structure, the above calibration process needs to be repeated to update the data stored in the control system.

[0063] Accordingly, this application obtains sample data through controlled variable experiments or flow-heat transfer coupling simulations, and then uses nonlinear least squares fitting to determine the coefficients, making the semi-empirical cooling rate control model adaptable to the actual operating conditions of the device. By calibrating and correcting the deviation between the theoretical model and the actual physical process, the reliability of the cooling rate control model calculation results is improved, providing an accurate model basis for subsequent back-calculation of pulsating airflow parameters and closed-loop control of aluminum coil cooling, further reducing the risk of overcooling or undercooling in the cooling process.

[0064] In some embodiments, the convective heat transfer coefficient during the high flow rate phase Convection heat transfer coefficient at low flow rate , representing the convective heat transfer coefficients under the conditions of high flow rate and low flow rate stages of the pulsating airflow, respectively, without considering the additional enhancement effect of pulsating disturbance. , It can be determined through cooling tests, flow field simulation, or empirical correlations calibrated through experiments.

[0065] The first method is an experimental measurement: Maintaining the specifications, ambient temperature, and flow channel structure parameters of the hot-rolled aluminum coil consistent with actual production conditions; disabling the pulse modulation function, and conducting two independent cooling tests by applying a constant airflow rate corresponding to both the high-flow-rate and low-flow-rate stages. During the tests, the temperature change curve of the hot-rolled aluminum coil's outer surface over time is collected, and the equivalent average temperature of the aluminum coil is calculated using the temperature correction relationship. Based on the cooling rate calculation formula for hot-rolled aluminum coils, and assuming the radiative heat transfer term is calculable, the convective heat transfer coefficient under the corresponding airflow rate is calculated by reverse deduction. The high-flow-rate constant-airflow test yields... Low flow rate constant air volume test results This method is based directly on testing with physical devices, and the determined values ​​closely match the actual working conditions on site.

[0066] The second approach involves coupled flow field and heat transfer simulation: a geometric simulation model consistent with the actual device is established, and the inlet airflow boundary conditions corresponding to the high and low flow stages are input respectively. Two sets of steady-state simulation calculations are then performed. Post-processing extracts the heat transfer data from the inner and outer surfaces of the aluminum coil. The convective heat transfer coefficient is calculated using the wall heat flux density and wall-fluid temperature difference output by the simulation software. and This method eliminates the need for physical testing, making it suitable for obtaining preliminary parameters before manufacturing a device prototype.

[0067] The third method is an empirical correlation calculation method calibrated through experiments: For the internal and external air-cooled flow channels of this application, applicable forced convection heat transfer correlations are selected respectively. The convective heat transfer coefficients of the corresponding flow channels in the high and low flow stages are calculated using parameters such as the Nusselt number, Reynolds number, and Prandtl number. Then, based on the heat transfer areas of the inner hole surface, outer circumferential surface, and end face, area weighting is performed to obtain the overall equivalent convective heat transfer coefficient under the corresponding air supply conditions. The correction coefficients in the empirical correlations should be corrected through experimental or simulation results to reduce the deviation between the empirical formulas and the actual device.

[0068] When the convective heat transfer coefficient in the high flow stage Convection heat transfer coefficient at low flow rate Once determined, the data is stored in the control system and can be directly retrieved for subsequent cooling rate calculations. When changing to different specifications of hot-rolled aluminum coils or modifying the flow channel structure, the data needs to be re-determined. and The value is determined and the data stored internally in the control system is updated.

[0069] Accordingly, this application provides a variety of and The determination method can be either physical test calibration, simulation pre-calculation, or empirical formula estimation, adapting to different engineering stages such as prototype development, early-stage simulation evaluation, and on-site debugging; at the same time, it clarifies the physical boundaries of parameters, decouples the contribution of basic convection heat transfer from the contribution of pulsating disturbance enhancement, prevents the repeated superposition of model parameters, and improves the accuracy of the calculation results of the cooling rate control model.

[0070] In some embodiments, the entire process of cooling the hot-rolled aluminum coil from the post-rolling temperature to the target temperature is divided into three stages: initial cooling, intermediate cooling, and final cooling. The cooling rate in the initial cooling stage is greater than that in the intermediate cooling stage, and the cooling rate in the intermediate cooling stage is greater than that in the final cooling stage.

[0071] Specifically, the post-rolling temperature is the body temperature of the hot-rolled aluminum coil when it is finished rolling and exits the coil, which can generally reach above 300℃; the target temperature is the exit temperature required by subsequent processes for the hot-rolled aluminum coil, which is generally room temperature. The three stages are divided according to the sequence of the continuous cooling process of the hot-rolled aluminum coil. After the initial cooling stage, the middle cooling stage begins, and after the middle cooling stage, the final cooling stage begins. The three stages are sequentially connected, covering the entire cooling process of the aluminum coil from the high post-rolling temperature to the target temperature.

[0072] Hot-rolled aluminum coils at high temperatures have relatively good plasticity and can withstand relatively faster cooling rates. Therefore, a higher cooling rate is used in the initial cooling stage to shorten the overall cooling time and improve production turnover efficiency. As the overall temperature of the hot-rolled aluminum coil decreases in the middle cooling stage, the cooling rate is appropriately reduced to ease the internal temperature gradient. In the final cooling stage, the overall temperature of the hot-rolled aluminum coil is already low, so the cooling rate is further reduced to avoid the accumulation of residual stress inside the aluminum coil caused by rapid cooling in the low-temperature range.

[0073] It should be noted that the cooling rate at each stage is not a fixed value and can be adjusted adaptively based on the grade, thickness, diameter, and production process requirements of the hot-rolled aluminum coil. The control system pre-stores the target cooling rate for each cooling stage. During the cooling operation, the target cooling rate for the current stage is used as the model's cooling rate, based on the cooling rate control model. Input the parameters and solve them in reverse to obtain the corresponding pulsating airflow parameters for that stage, thereby guiding the adjustment of the pulsating airflow.

[0074] Accordingly, this application divides the complete cooling process of hot-rolled aluminum coils into three stages: initial cooling, middle cooling, and final cooling, and sets progressively decreasing cooling rates. In the initial cooling stage, a higher cooling rate is used to leverage the good plasticity of the aluminum coil at high temperatures, ensuring cooling production efficiency. As the temperature of the aluminum coil gradually decreases, the target cooling rate is progressively reduced to suppress the generation of excessive temperature gradients within the aluminum coil, reduce residual stress accumulation, and avoid quality problems such as aluminum coil warping and out-of-tolerance sheet shape, thus achieving a balance between cooling efficiency and aluminum coil product quality.

[0075] In some embodiments, the initial cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is above 200°C, the middle cooling stage is when the outer surface temperature is between 100°C and 200°C, and the final cooling stage is when the outer surface temperature is below 100°C. During the cooling process, the control system determines the cooling stage based on the real-time outer surface temperature of the hot-rolled aluminum coil collected by the temperature detection device. It should be noted that the above temperature thresholds are not unique fixed values ​​and can be adaptively adjusted according to the alloy grade, coil thickness, coil diameter, and subsequent process requirements of the hot-rolled aluminum coil.

[0076] In some embodiments, a closed-loop regulation logic based on rate deviation is established in each cooling stage to achieve dynamic correction of pulsating airflow parameters. After dividing the cooling process into initial, middle, and final stages according to the outer surface temperature of the hot-rolled aluminum coil, the same closed-loop regulation process is executed within each cooling stage. The specific process is as follows: During each cooling stage, the outer surface temperature of the hot-rolled aluminum coil is collected. The actual cooling rate, or actual cooling rate, is calculated using the temperature difference and time interval between different moments. The specific calculation formula is as follows:

[0077] in, The actual cooling rate of hot-rolled aluminum coil, in units of... ; for The outer surface temperature of hot-rolled aluminum coil at any given time, in units of ; for The outer surface temperature of hot-rolled aluminum coil at any given time, in units of ; Sampling time, in units of ; The time interval between two consecutive temperature samples, in units of .

[0078] It should be noted that the external surface temperature used in the calculation process can also be converted into an equivalent average temperature according to the temperature correction relationship mentioned above before calculating the actual cooling rate. The actual cooling rate of the hot-rolled aluminum coil is compared with the preset target cooling rate for this cooling stage to obtain the rate deviation.

[0079] When the rate deviation is within the preset allowable deviation range, the pulsation frequency, duty cycle, and air volume during the high-flow phase of the pulsating airflow remain constant. The preset allowable deviation range is a deviation dead zone pre-stored in the control system and can be set using either absolute or relative deviation. By setting the allowable deviation range, temperature detection noise and calculation of minute disturbances that cause frequent adjustment jitter in the air supply actuator can be avoided, thus improving the system's operational stability.

[0080] When the rate deviation exceeds the preset allowable deviation range, and the actual cooling rate is lower than the target cooling rate, increase the duty cycle and / or the air volume during the high-flow stage. A low actual cooling rate indicates insufficient current cooling intensity, and the hot-rolled aluminum coil cooling does not meet process expectations. Increasing the duty cycle increases the time proportion of the high-flow stage within a pulse cycle, and increasing the air volume during the high-flow stage increases the peak air volume. Both can improve the equivalent convective heat transfer capacity and accelerate the cooling of the aluminum coil. In practice, you can adjust only the duty cycle and only the air volume during the high-flow stage, or you can adjust both simultaneously. Of course, you can also increase the pulse frequency within the set range, which can increase the Strouhal number, thereby increasing the pulse heat transfer enhancement term and improving the equivalent convective heat transfer capacity.

[0081] When the rate deviation exceeds the preset allowable deviation range, and the actual cooling rate is higher than the target cooling rate, reduce the duty cycle and / or the air volume during the high-flow stage. A high actual cooling rate indicates excessive cooling intensity, causing the hot-rolled aluminum coil to cool too quickly and potentially creating an excessive internal temperature gradient. Reducing the duty cycle and / or the air volume during the high-flow stage can decrease the overall heat exchange capacity, bringing the actual cooling rate back to the target range. Alternatively, one or both parameters can be adjusted, such as the duty cycle or the air volume during the high-flow stage. The high-pulsation frequency can also be reduced within the set range to weaken the cooling intensity.

[0082] Accordingly, this application introduces a rate deviation closed-loop adjustment mechanism on the basis of staged cooling, sets an allowable deviation dead zone to suppress system jitter; according to the deviation direction of the actual cooling rate from the target cooling rate, the duty cycle and air volume in the high flow stage are adjusted in a targeted manner, and the cooling rate deviation caused by environmental disturbances, aluminum coil specification deviations and other factors are automatically compensated, so that the aluminum coil follows the target cooling rate as much as possible in each cooling stage, reducing the occurrence of insufficient cooling or overcooling, further improving the process controllability of the hot-rolled aluminum coil cooling process, and ensuring the product quality of the hot-rolled aluminum coil after cooling.

[0083] See Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 This application also provides a hot-rolled aluminum coil cooling device for implementing a forced air cooling control method for hot-rolled aluminum coils. The device includes an air-cooling box 1 and an air supply unit 2.

[0084] An air-cooled chamber 11 extends horizontally and is open at both ends within the air-cooled box 1. The air-cooled chamber 11 is used to accommodate the hot-rolled aluminum coil 5. The open ends of the air-cooled chamber 11 facilitate the loading and unloading of the hot-rolled aluminum coil 5 and allow airflow and hot air from the hot-rolled aluminum coil 5 to be discharged from the chamber. During operation, the hot-rolled aluminum coil 5 is placed inside the air-cooled chamber 11, with the axial direction of the aluminum coil aligned with the extending direction of the air-cooled chamber 11.

[0085] The air supply unit 2 includes a pulsed air inlet duct 21, a spiral air guide shroud 22, a central guide duct 23, and spiral fins 24. The spiral air guide shroud 22 is a horizontally arranged hollow conical structure, with its large end opening larger than its small end opening. In this embodiment, the spiral air guide shroud 22 is a hollow frustum structure, with its large end connected to one end of the air-cooled chamber 11 and its small end connected to the coaxially arranged pulsed air inlet duct 21. The end of the pulsed air inlet duct 21 away from the spiral air guide shroud 22 is connected to a cooling air source. The cooling airflow is periodically adjusted by the variable frequency speed control mode of the fan or by an electronically controlled pulsed valve located in the pulsed air inlet duct 21 to deliver pulsed airflow. The pulsed airflow can be modulated as a rectangular wave or an approximately rectangular wave.

[0086] The central guide pipe 23 is coaxially disposed inside the spiral air guide shroud 22. The central axis of the central guide pipe 23 is coaxial with the spiral air guide shroud 22, the pulsating air inlet pipe 21, and the hot-rolled aluminum coil 5 after placement. Several spiral ribs 24 are evenly distributed around the central guide pipe 23 and the spiral air guide shroud 22, and each spiral rib 24 extends spirally along the axial direction of the central guide pipe 23. In this embodiment, the number of spiral ribs 24 is 3 to 16, determined by calculation based on specific cooling conditions.

[0087] The spiral rib 24 has two functions: first, it serves as a connecting support component to achieve coaxial fixation of the central guide pipe 23 inside the spiral air guide shroud 22; second, it plays a guiding role, with the airflow passing through the annular space between the central guide pipe 23 and the spiral air guide shroud 22 generating a circumferential velocity component under the guidance of the spiral rib 24, providing a flow basis for the subsequent formation of a spiral wall-attached flow on the outer surface of the hot-rolled aluminum coil 5.

[0088] See Figure 6 Spiral installation angle The angle between the tangent to the centerline of the spiral fin 24 at a specified location and the radial reference line at that location. The axial velocity component determines the transport capacity of the airflow along the length of the aluminum coil, while the circumferential velocity component determines the airflow's coverage of the outer wall of the aluminum coil and the intensity of disturbance. When the spiral installation angle is small, the circumferential velocity component is insufficient, and the airflow mainly flows axially, resulting in insufficient circumferential coverage of the outer wall. When the spiral installation angle is large, the circumferential velocity increases, but the axial transport capacity decreases, and the flow resistance increases. Therefore, in the specific design process, the spiral installation angle is adjusted according to the aluminum coil size, cooling airflow, and target heat exchange path length. A matching design was performed, and the spiral mounting angle that meets the requirements for airflow coverage and pressure loss was determined through flow field analysis. In this embodiment, the spiral mounting angle... The range is 20° to 55°.

[0089] The inner cavity of the central guide pipe 23 connects the pulsating air inlet pipe 21 and the air-cooled chamber 11, thus forming the inner air-cooled flow channel 25. A portion of the pulsating airflow delivered from the pulsating air inlet pipe 21 enters the inner cavity of the central guide pipe 23, flows out through the inner air-cooled flow channel 25 to the air-cooled chamber 11, and then flows into the inner hole of the hot-rolled aluminum coil 5, flowing axially along the inner hole of the aluminum coil, sweeping and cooling the inner surface of the hot-rolled aluminum coil 5.

[0090] The annular space between the central guide pipe 23 and the spiral air guide shroud 22 connects the pulsating air inlet pipe 21 and the air-cooled chamber 11, thus forming the outer air-cooled flow channel 26. Another part of the pulsating airflow enters the annular outer air-cooled flow channel 26, and under the guidance of the spiral ribs 24, it forms a rotating airflow. After flowing out of the outer air-cooled flow channel 26, it forms a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil 5, thereby cooling the outer surface of the hot-rolled aluminum coil 5.

[0091] It should be noted that after the pulsating airflow is output from the pulsating air inlet pipe 21, it is split into two streams through the inner air cooling channel 25 and the outer air cooling channel 26 before reaching the end of the hot-rolled aluminum coil 5. The two streams of airflow after splitting inherit the flow pulsation characteristics of the pulsating airflow output from the upstream pulsating air inlet pipe 21. The two streams of airflow synchronously complete the periodic alternation of the high flow rate stage and the low flow rate stage, respectively implementing pulsating air cooling on the inner and outer surfaces of the aluminum coil.

[0092] The process of cooling the hot-rolled aluminum coil 5 using the hot-rolled aluminum coil cooling device provided in this application embodiment is as follows: The rolled hot-rolled aluminum coil 5 is hoisted and placed inside the air-cooling chamber 11, ensuring that the end of the hot-rolled aluminum coil 5 faces the air supply unit 2, and the inner hole of the aluminum coil is coaxial with the central guide pipe 23; the system obtains the initial temperature of the hot-rolled aluminum coil 5 after rolling, and retrieves the preset target cooling rate for each stage according to the aluminum coil grade and specifications; the pulsed air source is activated, and the pulsed airflow is sent into the spiral air guide hood 22 through the pulsed air inlet pipe 21. The airflow is divided into two paths, one of which is sprayed into the inner hole of the hot-rolled aluminum coil 5 through the inner air-cooling channel 25, axially sweeping the inner surface of the aluminum coil; the other path is... The external air cooling channel 26 is guided by the spiral ribs 24 to form a spiral wall-attached flow that scours the outer surface of the aluminum coil. The temperature detection device collects the outer surface temperature of the hot-rolled aluminum coil 5 in real time. The control system determines the current cooling stage based on the outer surface temperature, calls the corresponding control logic, and adjusts the pulsation frequency, duty cycle, and air volume of the pulsating airflow in a closed loop. After heat exchange, the hot air is discharged from the open end of the air-cooled chamber 11 away from the air supply unit 2. When the temperature of the hot-rolled aluminum coil 5 drops to the target discharge temperature set by the process, the pulsating air source stops supplying air, completing the cooling process. The cooled hot-rolled aluminum coil 5 can then be lifted out of the air-cooled chamber 11.

[0093] Accordingly, the cooling device of this application serves as the hardware carrier for implementing the aforementioned forced air cooling control method. Relying on the combined structure of the spiral air guide shroud 22, the central guide pipe 23, and the spiral ribs 24, it can naturally split the pulsating airflow into the inner air cooling channel 25 and the outer air cooling channel 26 by inputting pulsating airflow through only one pulsating air inlet pipe 21, thereby achieving synchronous cooling of the inner and outer surfaces of the aluminum coil's inner hole, respectively. The spiral ribs 24 not only secure the central guide pipe 23 but also guide the external airflow in a swirling manner, ensuring the generation of spiral wall-attached flow on the outer surface. All components of the device are arranged coaxially, and the airflow direction matches the axial direction of the aluminum coil, reducing airflow loss and providing a hardware structural foundation for improving the cooling efficiency and temperature uniformity of the aluminum coil.

[0094] In some embodiments, see Figure 2 , Figure 3The air supply unit 2 includes multiple units. The multiple air supply units 2 are located on the same side of the air-cooled chamber 11 and are arranged in parallel along a horizontal direction that extends perpendicular to the air-cooled chamber 11. The large end of the spiral air guide shroud 22 of each air supply unit 2 is connected to the air-cooled chamber 11.

[0095] Specifically, the air supply unit 2 includes two or more units, and the pulsating air inlet pipe 21 of each air supply unit 2 is connected to an external pulsating air source, which can be controlled individually or in a unified coordinated manner. The large end of the spiral air guide shroud 22 of each air supply unit 2 is connected to the same air-cooled chamber 11, so that the pulsating airflow output by each air supply unit 2 can be diverted through the inner air-cooled flow channel 25 and the outer air-cooled flow channel 26 and then enter the air-cooled chamber 11, respectively acting on the inner and outer surfaces of the corresponding hot-rolled aluminum coil 5.

[0096] Accordingly, this arrangement allows multiple hot-rolled aluminum coils 5 to be accommodated simultaneously in the air-cooled chamber 11. Each hot-rolled aluminum coil 5 is cooled by a corresponding set of air supply units 2 through synchronous internal and external pulsed air cooling, achieving parallel cooling of multiple aluminum coils. Each air supply unit 2 is located on the same side of the air-cooled chamber 11 and arranged horizontally, with a compact structure and centralized arrangement of air source and pipeline, which facilitates unified management and parameter coordination of the control system. This improves the processing capacity of the cooling production line without significantly increasing the equipment footprint and ensures continuous production rhythm.

[0097] In order to expedite the removal of hot air from the air-cooled chamber 11 after the hot-rolled aluminum coil 5 has cooled down, see [reference needed]. Figure 2 , Figure 3 The top of the air-cooled box 1, which is away from the air supply unit 2, is provided with multiple heat dissipation windows 12; the number of heat dissipation windows 12 is the same as the number of air supply units 2, and they correspond one-to-one.

[0098] In some embodiments, see Figure 7 The cross-sectional area of ​​the inner hole of the central guide pipe 23 gradually decreases along the direction from the pulsating air inlet pipe 21 to the air-cooled chamber 11, and the relationship of the change in cross-sectional area is as follows:

[0099] in, The cross-sectional area at the current location, in units of ; This is the cross-sectional area of ​​the entrance end, in units of... ; This refers to the cross-sectional area of ​​the outlet end, in units of... ; The axial length of the central guide tube, in units of... ; The distance between the current location and the entrance, in units of ; The flow channel gradient index.

[0100] Specifically, the inner hole of the central guide pipe 23 is an internal air-cooled flow channel 25, the cross-sectional area of ​​which is determined by the inlet end. The axis decreases smoothly along the power function relationship described above until the outlet end. This creates a gradually narrowing flow channel that contracts along the flow direction. As the pulsating airflow flows in from the inlet, the cross-sectional area of ​​the channel gradually decreases, and the axial velocity of the airflow increases along the path while maintaining continuous flow, thus avoiding local eddies and pressure loss caused by abrupt changes in cross-section.

[0101] This model ensures that the cross-sectional area of ​​the internal air-cooled channel 25 continuously decreases along the airflow direction, and the degree of contraction at different axial positions of the channel can be changed by adjusting the channel gradient index. The larger the channel gradient index, the gentler the contraction near the inlet and the more intense the contraction near the outlet, and vice versa. In practice, it can be matched and set according to the specifications of the hot-rolled aluminum coil 5, the cooling air volume and other process conditions.

[0102] The flow channel gradient index can be determined based on the fan's rated pressure, target outlet velocity, and allowable pressure loss of the flow channel. In this embodiment, the flow channel gradient index is... The value is 1.2 to 3.5. When the inlet velocity of the flow channel is low and it is necessary to increase the outlet jet velocity, a smaller value should be selected. A larger value is selected to enhance the initial contraction effect; when the fan pressure margin is insufficient or it is necessary to reduce friction resistance, a larger value is selected. Values ​​were adjusted to slow down the rate of change of cross-sectional area. Different values ​​were obtained through flow field calculations. The results of velocity distribution and pressure loss under the given conditions were analyzed, and the optimal combination of airflow velocity uniformity and pressure loss was selected. The value is used as a design parameter.

[0103] Correspondingly, the use of a power-function gradient cross-sectional area inner channel can axially redistribute the airflow entering the inner hole of the hot-rolled aluminum coil 5, compensating for the kinetic energy attenuation caused by frictional resistance and jet diffusion during the airflow along the inner hole, ensuring that the airflow maintains sufficient sweeping velocity at all positions along the length of the inner hole of the aluminum coil, and improving the axial uniformity of the inner surface cooling; at the same time, through the gradient index of the flow channel... The adjustment can flexibly match the flow channel shrinkage law for different aluminum coil specifications, improving the adaptability of the internal air-cooled flow channel 25 to different working conditions.

[0104] In some embodiments, see Figure 2 , Figure 3 The air-cooled box 1 has an open bottom structure. The two side walls of the bottom of the air-cooled box 1 are slidably connected to the support platform 3. The support platform 3 is provided with a cooling station 31 and a loading and unloading station 32 in sequence along the extension direction of the air-cooled chamber 11. The cooling station 31 is provided with an aluminum coil base 4 for supporting the hot-rolled aluminum coil 5. The air-cooled box 1 can move back and forth between the cooling station 31 and the loading and unloading station 32.

[0105] Specifically, two parallel tracks 33 are fixed on the support platform 3, and the two side walls of the bottom of the air-cooled box 1 are slidably connected to the two tracks 33 respectively. During operation, the air-cooled box 1 is completely covered above the hot-rolled aluminum coil 5, and the air-cooled box 1 and the support platform 3 together form a relatively closed cooling space to reduce the leakage of cold air. The air-cooled box 1 can be driven by a drive mechanism (not shown in the figure) to move back and forth between the cooling station 31 and the loading and unloading station 32 along the tracks 33. The bottom of the air-cooled box 1 can be fixed with a high-temperature resistant sealing structure that slides and seals with the support platform 3 to prevent airflow leakage. In this embodiment, three sets of aluminum coil bases 4 are fixed at the cooling station 31 of the support platform 3, and each set of aluminum coil bases 4 includes two coaxially arranged aluminum coil bases 4.

[0106] When the air-cooled box 1 moves to the cooling station 31, the air-cooled box 1 covers the hot-rolled aluminum coil 5 placed on the aluminum coil base 4. The air supply unit 2 delivers pulsating airflow into the air-cooled chamber 11 to force-cool the hot-rolled aluminum coil 5. After cooling is completed, the air-cooled box 1 moves along the bearing platform 3 to the loading and unloading station 32, so that the hot-rolled aluminum coil 5 is fully exposed, making it convenient for the crane to lift out the cooled aluminum coil and to lift the new aluminum coil to be cooled into place. Then the air-cooled box 1 moves back to the cooling station 31 for the next round of cooling operation.

[0107] Accordingly, this application sets the air-cooled box 1 as an open-bottom structure that can reciprocate relative to the bearing platform 3, so that it can achieve covered cooling at the cooling station 31 and avoid the hot-rolled aluminum coil 5 at the loading and unloading station 32. This makes the hoisting and unloading of aluminum coils not interfere with the air-cooled box 1, and the loading and unloading operations are convenient. At the same time, the air-cooled box 1 can complete the loading and unloading of aluminum coils without lifting the whole box, reducing the frequency of hoisting large components, reducing operational risks, and balancing cooling performance with the convenience of on-site production operations.

[0108] Example 1: This embodiment employs a combined structure of a central guide tube 23 and a spiral rib 24. The hollow guide cylinder is used to guide a portion of the pulsating airflow into the inner bore region of the hot-rolled aluminum coil 5, while the spiral rib 24 guides another portion of the pulsating airflow to the outer circumferential surface of the hot-rolled aluminum coil 5. The spiral installation angle of the spiral rib 24 is set to 35°.

[0109] In this embodiment, the specifications and material properties of the hot-rolled aluminum coil are kept fixed. The initial temperature of the aluminum coil is 320℃, the target cooling temperature is 35℃, and the cooling air inlet temperature is 20℃. A CFD transient fluid-structure interaction heat transfer model is used for simulation calculations. The highest temperature across the entire computational domain of the aluminum coil is used as the criterion for switching cooling stages and determining the termination of cooling. When the highest temperature drops to 200℃, the cooling phase transitions to the middle stage; when it drops to 100℃, the cooling phase transitions to the end stage; and when it does not exceed 35℃, the cooling is considered complete. After cooling, the difference between the highest and lowest temperatures across the entire domain is used to evaluate the cooling uniformity. The specific steps are as follows: Initial cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from 320℃ to approximately 200℃. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0110] Using the arithmetic mean of the initial temperature (320℃) and the final temperature (200℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0111] Mid-cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from approximately 200°C to approximately 100°C. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0112] Using the arithmetic mean of the initial temperature (200℃) and the final temperature (100℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0113] Final cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from approximately 100°C to approximately 35°C. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0114] Using the arithmetic mean of the initial temperature (100℃) and the final temperature (35℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0115] CFD simulation settings: The flow channel outlet is set as a pressure outlet, the flow channel wall is set as a non-slip wall, and a fluid-structure interaction heat transfer interface is set between the aluminum coil and the cooling airflow, while also taking into account the radiation heat transfer on the aluminum coil surface; the initial temperature of the aluminum coil solid domain is set to 320℃ during the initial cooling phase; when the maximum temperature of the entire aluminum coil domain drops to 200℃, the current temperature field and flow field are retained as the initial conditions for the middle cooling phase, and the inlet periodic velocity boundary is switched; when the maximum temperature of the entire domain drops to 100℃, the temperature field and flow field are retained as the initial conditions for the final cooling phase, and the inlet periodic velocity boundary is switched again.

[0116] CFD calculations show that the hollow guide cylinder can continuously guide part of the pulsating airflow into the inner hole of the aluminum coil, while the spiral ribs cause another part of the airflow to generate a circumferential velocity component, forming a continuous spiral wall-attached flow along the outer circumference of the aluminum coil. When the highest temperature across the entire aluminum coil drops to 35℃, the maximum temperature difference across the entire area is less than 6℃; the initial cooling time is 96.64 min, the middle cooling time is 176.36 min, and the final cooling time is 402.12 min. The total cooling time is 675.12 min. This embodiment can achieve simultaneous cooling of the inner hole and outer circumference of the aluminum coil, significantly improving the uniformity of the temperature field of the aluminum coil.

[0117] Example 2: This embodiment uses the same hot-rolled aluminum coil, central guide tube, and spiral fins as in Embodiment 1, with the spiral fins installed at a 35° angle. It adopts an energy-saving operation mode with lower cooling intensity. The remaining simulation conditions are consistent with those in Embodiment 1. The specific steps are as follows: Initial cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from 320℃ to approximately 200℃. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0118] Using the arithmetic mean of the initial temperature (320℃) and the final temperature (200℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0119] Mid-cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from approximately 200°C to approximately 100°C. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0120] Using the arithmetic mean of the initial temperature (200℃) and the final temperature (100℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0121] Final cooling phase: Reduce the maximum global temperature of the solid computational domain of the hot-rolled aluminum coil from approximately 100°C to approximately 35°C. (Settings...) , , ;Calculation obtained , , , Based on the empirical values ​​obtained from cooling tests, take... , ;Calculation obtained , .

[0122] Using the arithmetic mean of the initial temperature (100℃) and the final temperature (35℃) of the aluminum coil in this stage as the equivalent average temperature of the hot-rolled aluminum coil, and substituting it into the cooling rate control model, the cooling rate of the hot-rolled aluminum coil in this stage is obtained. The above calculations yielded... , , , This serves as the entry boundary condition for the CFD calculation in this stage.

[0123] The CFD model, boundary conditions, and stage switching logic are exactly the same as in Example 1. Simulation results show that after reducing the pulsation parameters, the airflow organization of the inner hole guidance and the spiral wall-attached flow on the outer surface remains effective; when the maximum temperature of the entire aluminum coil drops to 35℃, the maximum temperature difference across the entire region is less than 10℃; the initial cooling time is 115.16 min, the middle cooling time is 217.11 min, and the final cooling time is 483.64 min. The total cooling time is 815.91 min. This example proves that the device and control method of this application can still meet the target cooling temperature and uniformity requirements under energy-saving and load-reducing conditions.

[0124] Comparative Example 1: The specifications of the aluminum coil, initial / target temperature, pulsation frequency, duty cycle, peak air volume, and gradient flow channel structure of this comparative example are consistent with those of Example 1, except that the spiral ribs are removed and the outer airflow flows only along the aluminum coil axis; the stage switching logic and simulation model are the same as those of Example 1.

[0125] Simulation results: The circumferential velocity of the airflow on the outer side is significantly reduced, and multiple low-speed stagnation zones appear on the outer circumference; when cooled to 35°C, the maximum temperature difference across the entire area is greater than 8°C, and the average convective heat transfer coefficient of the outer wall is reduced by 18%–25% compared to Example 1; the total cooling time is 858.60 min, which is 183.48 min longer than Example 1, representing a 27.18% increase in cooling time. This comparative example demonstrates that relying solely on the central guide tube to improve heat transfer within the inner hole, without the spiral fins to generate spiral wall-attached flow, significantly degrades the cooling effect on the outer surface.

[0126] Comparative Example 2: The aluminum coil and temperature boundary conditions in this comparative example are the same as in Example 1, except that the central guide tube and spiral fins are removed, and the cooling airflow only blows radially from the outside of the aluminum coil onto the outer surface of the aluminum coil.

[0127] Simulation results: The outer surface of the aluminum coil cools rapidly, but the inner hole of the aluminum coil cannot directly contact the cooling airflow, resulting in severe thermal hysteresis in the coil core area, with the high-temperature zone concentrated near the inner hole for a long time; when cooled to 35°C, the temperature of the outer area of ​​the aluminum coil is close to the ambient temperature, and the maximum temperature difference across the entire area exceeds 14°C; the total cooling time is 1011.50 min, which is 336.38 min longer than that of Example 1, representing an increase of 49.83% in cooling time. This comparative example demonstrates that the traditional external radial air supply scheme results in asynchronous cooling inside and outside, leading to poor cooling efficiency and uniformity.

[0128] Comparative Example 3: This comparative example retains all the flow channel structures of Example 1, with the spiral fin installation angle at 35°; the pulsed air supply is cancelled and replaced with continuous constant air supply; the continuous air supply volume for each stage is taken as the periodic average air volume of the corresponding stage in Example 1, ensuring that the average air supply volume is the same as that in Example 1.

[0129] Simulation results: The spiral fins can still generate circumferential velocity in the airflow, but lack pulsating periodic disturbances, and the thermal boundary layer on the wall cannot be periodically disrupted; when cooled to 35°C, the maximum temperature difference across the entire area is 8-12°C, and the average heat transfer coefficient of the outer wall is reduced by 10%-15% compared to Example 1; the total cooling time is 770.39 min, which is 95.27 min longer than Example 1, representing an increase of 14.11% in cooling time. This comparative example demonstrates that the boundary layer disturbances caused by pulsating airflow enhance heat transfer and play a key role in the cooling gain of this application.

[0130] A horizontal comparison of Examples 1, 2, 1, 2, and 3 reveals that the technical effect of this application is achieved through the synergistic effect of three factors: internal cooling of the central guide tube, spiral wall flow formed by the spiral fins, and boundary layer disturbance caused by pulsating airflow. This effect is not due to gains from a single structure or parameter. Under the same initial temperature, target temperature, and similar or identical air supply conditions, the solution of this application can shorten the time required for the aluminum coil to reach the target cooling temperature, reduce the maximum temperature difference across the entire solid computational domain of the aluminum coil, and improve the average heat transfer coefficient of the outer wall, thereby achieving synergistic optimization among cooling rate, cooling uniformity, and air supply energy consumption.

[0131] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for controlling forced air cooling of hot-rolled aluminum coils, characterized in that, include: A pulsating airflow is delivered to the end of the hot-rolled aluminum coil in a direction parallel to the axial direction of the hot-rolled aluminum coil. The pulsating airflow has a periodically alternating high flow rate phase and a low flow rate phase, and the air volume delivered in the high flow rate phase is greater than the air volume delivered in the low flow rate phase. The pulsating airflow is divided into two parts before reaching the end of the hot-rolled aluminum coil. One part of the airflow enters the inner hole of the hot-rolled aluminum coil, flows axially, and sweeps and cools the inner surface. The other part of the airflow forms a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil and cools the outer surface. The outer surface temperature of the hot-rolled aluminum coil is detected, and at least one of the following is adjusted according to the outer surface temperature and the temperature change trend: pulsation frequency, duty cycle, and high flow rate air volume of the pulsating airflow.

2. The forced air cooling control method for hot-rolled aluminum coils according to claim 1, characterized in that, The pulsation frequency, duty cycle, and high-flow-rate air volume of the pulsating airflow are adjusted based on a pre-established cooling rate control model, which is as follows: in, The cooling rate of hot-rolled aluminum coil, in units of... ; The effective heat exchange area of ​​hot-rolled aluminum coil, in units of... ; The mass of hot-rolled aluminum coil, in units of... ; Specific heat capacity of hot-rolled aluminum coil material, unit: ; The equivalent convective heat transfer coefficient is expressed in units of 1000 ppm. ; The equivalent average temperature of hot-rolled aluminum coils, in units of... ; The temperature of the cooling air is expressed in units of _____. ; The surface emissivity of hot-rolled aluminum coil; This is the Stefan-Boltzmann constant, with units of 1. ; The duty cycle of the pulsating airflow; The convective heat transfer coefficient during the high flow rate stage is expressed in units of... ; The convective heat transfer coefficient is given at low flow rates, and the unit is _____. ; The amplitude coefficient for pulsating heat transfer enhancement; The heat transfer enhancement index is the pulsating heat transfer enhancement index. The pulsation frequency of the pulsating airflow, measured in units of... ; The hydraulic diameter of the characteristic flow channel, in units of _____. ; The effective flow area of ​​the channel before the pulsating airflow is split into two parts, in units of ; The high-flow-rate supply air volume before the pulsating airflow is split into two parts, measured in units of... .

3. The forced air cooling control method for hot-rolled aluminum coils according to claim 2, characterized in that, The amplitude coefficient of the pulsating heat transfer enhancement With the aforementioned pulsating heat transfer enhancement index The calibration is performed in the following manner: Under the condition that the specifications of the hot-rolled aluminum coil, ambient temperature, and flow channel structure parameters remain unchanged, cooling tests or flow field heat transfer coupling simulations are conducted by changing the pulsation frequency, duty cycle, and air volume during the high-flow stage of the pulsating airflow, respectively, to obtain the curves of the outer surface temperature of the hot-rolled aluminum coil over time under each working condition; the equivalent convective heat transfer coefficient for each working condition is calculated based on the temperature drop rate of the hot-rolled aluminum coil. The equivalent convective heat transfer coefficient was fitted using the nonlinear least squares method. With Strauhall The relationship between them yields the amplitude coefficient of pulsating heat transfer enhancement. With the pulsating heat transfer enhancement index .

4. The forced air cooling control method for hot-rolled aluminum coils according to any one of claims 1 to 3, characterized in that, The entire process of cooling the hot-rolled aluminum coil from the post-rolling temperature to the target temperature is divided into three stages: initial cooling, intermediate cooling, and final cooling. The cooling rate in the initial cooling stage is greater than that in the intermediate cooling stage, and the cooling rate in the intermediate cooling stage is greater than that in the final cooling stage.

5. The forced air cooling control method for hot-rolled aluminum coils according to claim 4, characterized in that, The initial cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is higher than 200°C; the middle cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is between 100°C and 200°C; and the final cooling stage is when the outer surface temperature of the hot-rolled aluminum coil is lower than 100°C.

6. The forced air cooling control method for hot-rolled aluminum coils according to claim 4, characterized in that, In each cooling stage, the actual cooling rate of the hot-rolled aluminum coil is calculated based on the outer surface temperature of the hot-rolled aluminum coil, and the rate deviation is obtained by comparing the actual cooling rate of the hot-rolled aluminum coil with the target cooling rate. When the rate deviation is within the preset allowable deviation range, the pulsation frequency, duty cycle and high flow rate of the pulsating airflow are kept constant. When the rate deviation exceeds the preset allowable deviation range and the actual cooling rate is lower than the target cooling rate, increase the duty cycle and / or the air volume during the high flow stage. When the rate deviation exceeds the preset allowable deviation range and the actual cooling rate is higher than the target cooling rate, the duty cycle and / or the air volume during the high flow stage are reduced.

7. A cooling device for hot-rolled aluminum coils, characterized in that, For implementing the forced air cooling control method for hot-rolled aluminum coils as described in any one of claims 1 to 6; It includes an air-cooled box (1) and an air supply unit (2). The air-cooled box (1) encloses an air-cooled chamber (11) that extends horizontally and is open at both ends. The air-cooled chamber (11) is used to accommodate hot-rolled aluminum coils (5). The air supply unit (2) includes a pulsed air inlet pipe (21), a spiral air guide shroud (22), a central guide pipe (23), and spiral ribs (24). The spiral air guide shroud (22) is a horizontally arranged hollow cone structure. Its large end is connected to one end of the air-cooled chamber (11), and its small end is connected to the coaxially arranged pulsed air inlet pipe (21). The pulsed air inlet pipe (21) is used to transport pulsed airflow. The central guide tube (23) is coaxially disposed inside the spiral air guide shroud (22), and a number of spiral ribs (24) are evenly distributed around the central guide tube (23) and the spiral air guide shroud (22). Each spiral rib (24) extends spirally along the axial direction of the central guide tube (23). The inner cavity of the central guide pipe (23) connects the pulsating air inlet pipe (21) and the air-cooled chamber (11) to form an inner air-cooled flow channel (25), which is used to allow a portion of the pulsating airflow to flow out and flow axially along the inner hole of the hot-rolled aluminum coil (5). The annular space between the central guide pipe (23) and the spiral air guide shroud (22) connects the pulsating air inlet pipe (21) and the air-cooled chamber (11) to form an external air-cooled flow channel (26), which is used to allow another part of the pulsating airflow to flow out and form a spiral wall-attached flow along the outer surface of the hot-rolled aluminum coil.

8. The hot-rolled aluminum coil cooling device according to claim 7, characterized in that, The air supply unit (2) includes multiple units, which are arranged side by side on the same side of the air-cooled chamber (11) and in a horizontal direction that extends perpendicular to the air-cooled chamber (11). The large end of the spiral air guide shroud (22) of each air supply unit (2) is connected to the air-cooled chamber (11).

9. The hot-rolled aluminum coil cooling device according to claim 7, characterized in that, The cross-sectional area of ​​the inner hole of the central guide pipe (23) gradually decreases along the direction from the pulsating air inlet pipe (21) to the air-cooled chamber (11), and the relationship of the change of the cross-sectional area is as follows: in, The cross-sectional area at the current location, in units of ; This is the cross-sectional area of ​​the entrance end, in units of... ; This refers to the cross-sectional area of ​​the outlet end, in units of... ; The axial length of the central guide tube, in units of... ; The distance between the current location and the entrance, in units of ; The flow channel gradient index.

10. The hot-rolled aluminum coil cooling device according to claim 7, characterized in that, The air-cooled box (1) has an open bottom structure. The two side walls of the bottom of the air-cooled box (1) are slidably connected to the support platform (3). The support platform (3) is provided with a cooling station (31) and a loading and unloading station (32) in sequence along the extension direction of the air-cooled chamber (11). The cooling station (31) is provided with an aluminum coil base (4) for supporting the hot-rolled aluminum coil (5). The air-cooled box (1) can move back and forth between the cooling station (31) and the loading and unloading station (32).

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