Foamed aluminum-aluminum alloy composite automotive battery pack tray and method of manufacture

Abstract

This invention discloses a foamed aluminum-aluminum alloy composite automotive battery pack tray and its manufacturing method, specifically relating to the technical field of electric vehicle battery pack components. The invention employs a composite structure of an aluminum alloy shell and a closed-cell foamed aluminum core layer, combined with positioning protrusions and reinforcing ribs. Through specific pretreatment and hot-pressing composite processes, an integrated tray is manufactured, effectively solving the problems of poor heat insulation and vibration reduction, and the difficulty in balancing strength and lightweight in traditional single aluminum alloy trays. It boasts advantages such as high strength, lightweight, good heat insulation and vibration reduction, strong interface bonding, and simple process for mass production. This improves battery safety and lifespan, making it suitable for industrial applications in electric vehicles.

Description

Technical Field

[0001] This invention relates to the field of automotive pallet technology, and in particular to an aluminum foam-aluminum alloy composite automotive battery pack pallet and its manufacturing method. Background Technology

[0002] This invention belongs to the technical field of electric vehicle battery pack components, specifically relating to an electric vehicle battery pack tray with a foamed aluminum-aluminum alloy composite structure, and also to the manufacturing process of this battery pack tray. As a core structural component that supports, fixes, and protects the battery module, the electric vehicle battery pack tray directly affects the safety, durability, and overall vehicle energy consumption of the battery system, and is a key functional component of the electric vehicle chassis system. With the increasing demands for range, safety, and lightweighting in new energy vehicles, battery pack trays face higher technical requirements in terms of structural strength, heat insulation and vibration reduction, weight control, and manufacturing feasibility. Developing high-performance composite structures and suitable industrial manufacturing processes has become an important development direction for the industry.

[0003] Currently, electric vehicle battery pack trays are generally made of a single aluminum alloy material, manufactured through conventional processes such as casting and stamping. They are widely used in battery pack assembly scenarios for various pure electric and hybrid vehicles, primarily fulfilling the functions of battery module support, positioning, and basic protection, while also meeting lightweight design requirements to some extent. Although single aluminum alloy trays are mature to manufacture, cost-effective, and widely used, with the increase in battery energy density and the upgrading of range requirements, traditional materials and structures are no longer sufficient to meet the needs of battery systems in terms of thermal management, vibration and shock resistance, and synergistic improvement in lightweighting. The industry is gradually exploring and researching composite structures of aluminum foam and aluminum alloys in an attempt to improve the overall performance of the trays.

[0004] The most prominent drawback of existing single aluminum alloy battery pack trays is their insufficient heat insulation and vibration damping performance. Aluminum alloy itself has limited heat insulation and buffering capabilities, and cannot effectively block heat transfer and absorb driving vibrations, which can easily lead to thermal runaway and performance degradation of the battery module, directly affecting battery life and driving safety. Summary of the Invention

[0005] The main objective of this invention is to provide a foamed aluminum-aluminum alloy composite automotive battery pack tray and its manufacturing method, which can effectively solve the problems involved in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A foamed aluminum-aluminum alloy composite automotive battery pack tray and its manufacturing method are disclosed. The foamed aluminum-aluminum alloy composite automotive battery pack tray includes an aluminum alloy shell, a foamed aluminum core layer, and a connecting structure. The aluminum alloy shell is grooved, and the inner wall is provided with uniformly distributed positioning protrusions. The foamed aluminum core layer is tightly filled inside the aluminum alloy shell and is tightly bonded to the inner wall of the aluminum alloy shell through a composite layer. The connecting structure is located at the edge of the aluminum alloy shell, and the bottom of the aluminum alloy shell is also provided with reinforcing ribs.

[0007] Preferably, the aluminum alloy shell is made of 6061 aluminum alloy, and the positioning protrusion is used to achieve precise positioning of the foam aluminum core layer within the aluminum alloy shell.

[0008] Preferably, the aluminum foam core layer is closed-cell aluminum foam with a density of 0.3-0.6 g / cm³. 3 The thickness is 10-20mm.

[0009] Preferably, the connection structure includes mounting holes and positioning pins for fixing the battery pack tray to the vehicle body, and the reinforcing ribs are used to improve the overall structural strength of the tray.

[0010] A method for manufacturing a car battery pack tray of aluminum foam-aluminum alloy composite as described in any of the above claims includes the following steps: raw material pretreatment, composite molding, and subsequent processing; the raw material pretreatment processes aluminum alloy sheet and aluminum foam respectively; the composite molding assembles the pretreated aluminum foam core layer with the aluminum alloy shell and then hot-presses the composite; the subsequent processing shapes and surfaces the hot-pressed composite.

[0011] Preferably, the process parameters for hot-pressing composite are: temperature 500-550℃, pressure 10-15MPa, and heat and pressure holding time 30-60min.

[0012] Preferably, in the raw material pretreatment step, the aluminum alloy sheet is cut and then successively polished, degreased, and pickled to remove the surface oxide layer and impurities; the foamed aluminum is cut to the matching size and then sandblasted to enhance the bonding force of the composite interface.

[0013] Preferably, the subsequent processing steps are as follows: cooling the hot-pressed composite to room temperature, trimming the edges, drilling mounting holes at preset positions, installing positioning pins and reinforcing ribs, and finally performing surface anti-rust treatment to obtain the finished product.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a battery pack tray with a foamed aluminum-aluminum alloy composite structure. The aluminum alloy shell provides structural strength and a mounting foundation, while the closed-cell foamed aluminum core layer offers advantages in lightweighting, heat insulation, and vibration damping. The two are firmly bonded together to form an integrated structure, significantly improving overall performance. This invention substantially reduces the tray's weight while ensuring load-bearing stiffness and structural reliability, achieving better lightweighting. Simultaneously, it effectively blocks external heat conduction, absorbs driving vibrations and impacts, reduces the risk of battery thermal runaway, and improves battery operational stability and lifespan. The overall structure has high molding precision and a strong interface bond. The manufacturing process is simple and controllable, suitable for industrial mass production, and can simultaneously meet the core requirements of new energy vehicles for safety, range, lightweighting, and low cost. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the manufacturing process of the battery pack tray of the present invention. Detailed Implementation

[0016] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0017] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments. All equivalent substitutions and parameter adjustments made based on the core concept of the present invention fall within the scope of protection of the present invention.

[0018] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments. All equivalent substitutions and parameter adjustments made based on the core concept of the present invention fall within the scope of protection of the present invention.

[0019] This invention belongs to the technical field of electric vehicle battery pack components. Please refer to [link / reference]. Figure 1 Specifically, this relates to a foamed aluminum-aluminum alloy composite electric vehicle battery pack tray and its preparation process, aiming to solve the technical problems of insufficient heat insulation and vibration reduction performance, difficulty in balancing lightweight and structural strength in existing single aluminum alloy battery pack trays, as well as the poor interfacial bonding, low molding accuracy, complex process, high production cost, and difficulty in industrial mass production of existing foamed aluminum-aluminum alloy composite processes.

[0020] Currently, electric vehicle battery pack trays, as the core component that carries battery modules, are mostly made of a single aluminum alloy and formed through conventional processes such as casting and stamping. They are widely used in the battery pack assembly of various electric vehicles, mainly to realize the functions of carrying and fixing battery modules, while also taking into account certain lightweight requirements.

[0021] However, in actual use, the inherent defects of a single aluminum alloy material are becoming increasingly apparent. In the high-temperature environment of summer, external heat can be easily transferred to the inside of the battery module through the aluminum alloy tray, causing the battery operating temperature to rise, accelerating the degradation of battery performance, and in severe cases, even triggering the risk of thermal runaway. The vibration and impact generated when the vehicle is driving on bumpy roads will also be directly conducted to the battery module through the aluminum alloy tray. Long-term vibration will cause the battery connection to loosen and the internal structure to be damaged, affecting the battery life and driving safety.

[0022] Meanwhile, in order to ensure the structural strength and rigidity of the pallet to withstand the weight of the battery module and the impact load during driving, the wall thickness of the single aluminum alloy pallet has to be increased. This not only significantly increases the weight of the pallet itself, which violates the lightweight design concept of electric vehicles, but also increases the consumption of raw materials and manufacturing costs, and reduces the vehicle's driving range.

[0023] Although some studies have attempted to use aluminum foam and aluminum alloy composites for the preparation of automotive parts, existing composite processes generally suffer from problems such as weak bonding at the composite interface, difficulty in controlling molding precision, complex process flow, and low production efficiency. As a result, aluminum foam-aluminum alloy composite structures have not been able to achieve large-scale industrial application, and it is difficult to fundamentally solve the inherent defects of single aluminum alloy battery pack trays.

[0024] The foamed aluminum-aluminum alloy composite electric vehicle battery pack tray disclosed in this invention adopts a composite structure that combines an aluminum alloy shell with a closed-cell foamed aluminum core layer. The aluminum alloy shell is made of 6061 aluminum alloy sheet, which has the characteristics of high strength, good processing performance and excellent welding performance, and can provide reliable structural support for the tray.

[0025] The aluminum alloy shell has a groove-shaped structure that fits the standard battery module installation size. Its internal cavity size is perfectly matched with the outer size of the aluminum foam core layer, which can provide a stable space for the aluminum foam core layer and bear the entire weight of the battery module.

[0026] The inner wall of the aluminum alloy shell is integrally formed with evenly distributed positioning protrusions. These positioning protrusions are arranged at equal intervals of 3-5 on each side of the circumference of the inner wall of the shell, and at equal intervals of 2-3 rows along the height of the shell. They can play a precise limiting role during the assembly of the foam aluminum core layer, effectively preventing the core layer from shifting or misaligning during assembly and subsequent hot pressing, and ensuring the molding accuracy and consistency of the composite structure.

[0027] The aluminum foam core layer is made of closed-cell aluminum foam material. Closed-cell aluminum foam has the characteristics of high porosity, low density, high specific strength, and excellent thermal insulation and vibration reduction performance. Its density is strictly controlled within the range of 0.3-0.6 g / cm³, and the thickness is set to 10-20 mm. This parameter range has been verified by a large number of tests. It can maximize its lightweight and thermal insulation and vibration reduction advantages while ensuring that the core layer has sufficient specific strength to withstand the load.

[0028] The foamed aluminum core layer is tightly filled into the internal cavity of the aluminum alloy shell. It is bonded to the inner wall of the aluminum alloy shell by hot pressing to form a continuous and dense composite layer. The two are firmly bonded and will not delaminate or fall off during long-term use under vibration and impact loads, which significantly improves the structural stability and service life of the pallet.

[0029] The bottom of the aluminum alloy shell is integrally formed with a grid-like distribution of reinforcing ribs. The height of the reinforcing ribs is 5-8mm, the width is 3-5mm, and the intersection angle is 90 degrees. This can further improve the overall rigidity and impact load resistance of the tray, effectively distribute the weight of the battery module and the dynamic load generated during driving, and prevent the tray from deforming under heavy load or impact.

[0030] The aluminum alloy shell has a connecting structure consisting of mounting holes and positioning pins on its edge. The mounting holes are prefabricated standard through holes that are evenly distributed around the circumference of the shell edge. The positioning pins cooperate with the mounting holes to enable the battery pack tray to be quickly and accurately assembled with the vehicle chassis, which greatly improves the work efficiency of the vehicle assembly line and reduces labor and time costs in the assembly process.

[0031] In practical applications, the above structure can be adapted to different usage scenarios and performance requirements. For example, the aluminum foam core layer can be replaced with gradient density closed-cell aluminum foam, so that its density gradually decreases from the side closest to the aluminum alloy shell to the inside. The high-density area on the outside ensures the bonding strength and structural support with the aluminum alloy shell, while the low-density area on the inside further improves the heat insulation and vibration reduction performance and the lightweight effect. This gradient structure can improve the heat insulation performance of the pallet by about 15% and reduce the weight by about 8% without reducing the overall strength. Alternatively, the material of the aluminum alloy shell can be replaced with 5052 aluminum alloy. 5052 aluminum alloy has better corrosion resistance and weldability, which can make the pallet better adapt to complex and harsh usage environments such as humidity, salt spray, and acid and alkali, and extend the service life of the pallet in special working conditions such as coastal areas and chemical industrial parks.

[0032] The present invention also provides a preparation process for the above-mentioned foamed aluminum-aluminum alloy composite electric vehicle battery pack tray. This process achieves a strong bond between foamed aluminum and aluminum alloy by optimizing the raw material pretreatment method and precisely controlling the hot pressing composite parameters. The process is simple and controllable, requires no complex special equipment, has high production efficiency and low production cost, and is suitable for industrial mass production.

[0033] First, a raw material pretreatment process is carried out. 6061 aluminum alloy sheet that meets national standards is selected and laser-cut according to the preset pallet shell size to ensure that the cutting accuracy is within ±0.5mm. Then, the cut aluminum alloy sheet is subjected to surface grinding, degreasing and pickling treatment in sequence.

[0034] The grinding process uses 80-120 grit sandpaper or abrasive wheels to remove burrs and rough protrusions from the surface of the sheet, achieving a surface roughness of Ra3.2 or less. The degreasing process involves soaking the sheet in an alkaline degreasing agent at 50-60℃ for 10-15 minutes to thoroughly remove oil and impurities from the surface, followed by rinsing with clean water. The pickling process involves soaking the sheet in a 10%-15% dilute nitric acid solution for 5-8 minutes to remove the oxide layer from the surface, followed by rinsing with clean water and drying. After these treatments, the aluminum alloy sheet surface is clean and free of impurities, providing a good foundation for subsequent composite interface bonding.

[0035] Simultaneously, closed-cell aluminum foam sheets are selected and CNC wire-cut according to the dimensions of the internal cavity of the aluminum alloy shell, ensuring a cutting accuracy within ±0.3mm. Then, the surface of the cut aluminum foam is sandblasted, with the sandblasting pressure controlled at 0.4-0.6MPa and 80-100 mesh quartz sand used. The impact of high-speed sand particles forms a uniform rough texture on the surface of the aluminum foam, significantly enhancing the mechanical interlocking force of the composite interface and further improving the bonding strength between the aluminum foam and the aluminum alloy.

[0036] After the raw material pretreatment is completed, the treated aluminum foam core layer is smoothly embedded into the internal cavity of the aluminum alloy shell. The position of the core layer is carefully adjusted to ensure that it fits perfectly with all the positioning protrusions on the inner wall of the shell, so as to ensure that the core layer is accurately positioned inside the shell and avoid displacement during the hot pressing process.

[0037] The assembled semi-finished product is placed steadily into the mold of the hot pressing equipment. The surface of the mold is pre-coated with a high-temperature release agent. After the mold is closed, the temperature and pressure are increased at a uniform rate. The hot pressing temperature is strictly controlled between 500-550℃ and the pressure is between 10-15MPa. The product is then kept at this temperature and pressure for 30-60 minutes.

[0038] Under high temperature and pressure, the surface of the aluminum alloy shell undergoes slight plastic deformation, interlocking with the rough surface of the aluminum foam core layer. At the same time, the interface atoms of the two diffuse into each other, forming a metallurgically bonded composite layer, thus achieving a strong integrated composite of aluminum foam and aluminum alloy.

[0039] After hot pressing is completed, stop heating and pressurizing, remove the workpiece from the hot pressing equipment, and place it in a ventilated and dry environment to cool naturally to room temperature. Avoid using rapid cooling methods such as water cooling or air cooling, which may cause internal stress in the workpiece and lead to deformation or cracking.

[0040] After cooling, the edges of the workpiece are CNC trimmed to remove excess material and burrs generated during hot pressing, ensuring that the edge flatness is within ±0.2mm. Then, mounting holes are drilled according to the preset positions, and positioning pins and reinforcing ribs are assembled. Finally, the entire workpiece is subjected to surface rust prevention treatment, which can be done by anodizing or electrostatic spraying of rust-preventive paint to form a dense protective film on the tray surface to prevent the tray from rusting during use. After all the above processes, the finished foamed aluminum-aluminum alloy composite electric vehicle battery pack tray can be obtained.

[0041] For high-end electric vehicle applications requiring even higher precision, the aforementioned hot-pressing composite process can be replaced with a vacuum brazing process, with a vacuum level of not less than 1×10⁻⁶. -3 In an environment with Pa, aluminum foam and aluminum alloy are composited by melting and solidifying aluminum-based brazing filler metal. This process can achieve higher composite precision and interfacial bonding strength, meeting the stringent requirements of high-end electric vehicles for battery pack trays.

[0042] Actual performance tests show that the foamed aluminum-aluminum alloy composite electric vehicle battery pack tray prepared using this invention reduces the overall weight by more than 20% compared to traditional single aluminum alloy battery pack trays, effectively reducing the overall energy consumption of electric vehicles and increasing the vehicle's range by 5%-8%. Its heat insulation performance is improved by more than 60%, and when the ambient temperature is 60℃, the surface temperature of the battery module can be controlled below 40℃, effectively blocking heat transfer from the high-temperature environment to the battery module and preventing thermal runaway due to overheating. Its vibration damping and energy absorption effect is improved by more than 50%, fully absorbing the vibration and impact loads generated during electric vehicle operation, reducing the vibration acceleration of the battery module, protecting the battery module from mechanical damage, and extending the battery's lifespan by more than 15%.

[0043] Meanwhile, the preparation process parameters of this invention are stable and controllable, the product qualification rate reaches over 98%, the production cost is reduced by about 30% compared with the existing composite process, the production efficiency is increased by over 40%, and large-scale industrial production can be achieved.

[0044] Currently, there are no foamed aluminum-aluminum alloy composite electric vehicle battery pack tray products on the market that are completely identical in structure and process to this invention. Most existing related products are single aluminum alloy trays or foamed aluminum composite experimental products that have not yet achieved industrial application. This invention can fill the market gap, adapt to the battery pack assembly needs of various pure electric and hybrid vehicles, and has broad market application prospects and significant economic benefits.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A foamed aluminum-aluminum alloy composite automotive battery pack tray, characterized in that, It includes an aluminum alloy shell, a foamed aluminum core layer, and a connecting structure; the aluminum alloy shell is grooved, and the inner wall is provided with evenly distributed positioning protrusions; the foamed aluminum core layer is tightly filled inside the aluminum alloy shell and is tightly bonded to the inner wall of the aluminum alloy shell through a composite layer; the connecting structure is set at the edge of the aluminum alloy shell, and the bottom of the aluminum alloy shell is also provided with reinforcing ribs.

2. The automotive battery pack tray made of foamed aluminum-aluminum alloy composite according to claim 1, characterized in that, The aluminum alloy shell is made of 6061 aluminum alloy, and the positioning protrusion is used to achieve precise positioning of the foam aluminum core layer inside the aluminum alloy shell.

3. The automotive battery pack tray made of foamed aluminum-aluminum alloy composite according to claim 1, characterized in that, The aluminum foam core layer is closed-cell aluminum foam with a density of 0.3-0.6 g / cm³. 3 The thickness is 10-20mm.

4. The automotive battery pack tray made of foamed aluminum-aluminum alloy composite according to claim 1, characterized in that, The connection structure includes mounting holes and positioning pins for fixing the battery pack tray to the vehicle body, and the reinforcing ribs are used to improve the overall structural strength of the tray.

5. A method for manufacturing a foamed aluminum-aluminum alloy composite automotive battery pack tray as described in any one of claims 1-4, characterized in that, Includes the following steps: Raw material pretreatment, composite molding, and subsequent processing; the raw material pretreatment processes aluminum alloy sheet and aluminum foam respectively; the composite molding assembles the pretreated aluminum foam core layer with the aluminum alloy shell and then hot-presses them together; the subsequent processing shapes and surfaces the hot-pressed composite.

6. The method for manufacturing the foamed aluminum-aluminum alloy composite automotive battery pack tray according to claim 5, characterized in that, The process parameters for hot-pressing composite are: temperature 500-550℃, pressure 10-15MPa, and heat and pressure holding time 30-60min.

7. The method for manufacturing the foamed aluminum-aluminum alloy composite automotive battery pack tray according to claim 5, characterized in that, In the raw material pretreatment step, the aluminum alloy sheet is cut and then polished, degreased, and pickled in sequence to remove the surface oxide layer and impurities; the foamed aluminum is cut to the matching size and then sandblasted to enhance the bonding force of the composite interface.

8. The method for manufacturing the foamed aluminum-aluminum alloy composite automotive battery pack tray according to claim 5, characterized in that, The subsequent processing steps are as follows: cool the hot-pressed composite part to room temperature, trim the edges, drill holes in the preset positions to process mounting holes, install positioning pins and reinforcing ribs, and finally perform surface anti-rust treatment to obtain the finished product.

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