1, Selection of Aluminum Alloy Materials
There are various types of aluminum alloys with different properties, and choosing the appropriate aluminum alloy is crucial for manufacturing high-quality battery cases. The common aluminum alloys used for battery casings are mainly 5 series, 6 series, and 7 series. 5 series aluminum alloy has good corrosion resistance, weldability, and processability, making it suitable for components that require moderate strength; The 6-series aluminum alloy has high strength while maintaining good workability and corrosion resistance, making it suitable for components that require high strength and good weldability; 7 series aluminum alloy is a high-strength aluminum alloy, but its welding performance is relatively poor, making it suitable for components with extremely high strength requirements.
In the manufacturing of automotive battery cases, suitable aluminum alloys are usually selected based on the specific usage environment and requirements of the case. For example, for battery cases that require significant impact and compression, higher strength 6 series or 7 series aluminum alloys may be chosen; For enclosures that prioritize corrosion resistance and processing performance, the 5 series aluminum alloy may be chosen.
2, Forming process
The molding process of aluminum alloy battery cases mainly includes two categories: casting and extrusion molding.
Casting process
Casting is a key process for mass production of aluminum alloy battery cases. Common casting methods include gravity casting, anti gravity casting (such as low-pressure casting, differential pressure casting, and pressure regulating casting), investment casting precision casting, and gypsum mold casting.
Gravity casting: suitable for components with simple shapes and large wall thicknesses. However, the surface roughness of castings cast by gravity casting is relatively high, and the accuracy is relatively low.
Anti gravity casting: Using external pressure to fill and solidify the alloy liquid from bottom to top, it has the characteristics of stable filling, pressure solidification, controllable filling speed, and reasonable temperature field distribution. The casting has good mechanical properties, dense structure, and few defects.
Investment casting: With high dimensional accuracy and surface smoothness, flexible design, it can be used to cast highly complex castings. At the same time, the production process is environmentally friendly and the recovery rate of old sand is high.
Gypsum casting: suitable for manufacturing castings with high dimensional accuracy and low residual stress. Gypsum molds can accurately replicate patterns, with low surface roughness of castings, and are easy to achieve complete shaping of thin-walled parts.
Extrusion molding
Extrusion molding is the process of placing a metal billet into a mold cavity and applying strong pressure to induce directional plastic deformation, thereby obtaining the desired cross-sectional shape and size of the part. Aluminum alloy battery cases formed by extrusion have high precision, good surface quality, and can improve material utilization and yield. But extrusion molding is only suitable for products with equal cross-sections, and the shape cannot be too complex.
3, Welding technology
The welding of aluminum alloy is one of the key steps in manufacturing battery casings. Common welding methods for aluminum alloys include tungsten inert gas welding (TIG welding), melting electrode argon arc welding (MIG welding), laser welding, resistance welding, electron beam welding, etc.
Tungsten inert gas welding: suitable for welding thin plates and small components, with high strength, good plasticity, and high quality of welded joints.
Melting electrode argon arc welding: High welding efficiency, easy to achieve automatic welding and semi-automatic welding, suitable for welding various thicknesses of aluminum and aluminum alloys.
Laser welding: With fast welding speed, small heat affected zone, and minimal deformation, it is suitable for high-precision and high demand welding.
In the welding process of automotive battery cases, it is necessary to strictly control the welding parameters and process conditions to ensure the quality and performance of the welded joints. At the same time, it is necessary to conduct necessary inspections and evaluations on the welded joints to ensure that they meet the design and usage requirements.
4, Surface treatment
The surface treatment of aluminum alloy battery cases is of great significance for improving their corrosion resistance and aesthetics. Common surface treatment methods include anodizing, spraying, electroplating, etc.
Anodizing: By forming a dense layer of aluminum oxide film on the surface of aluminum alloy, its corrosion resistance and hardness are improved. The anodized film has good adhesion and wear resistance, and is rich in color, which can be used for decoration and protection.
Spray coating: A protective film is formed on the surface of aluminum alloy by spraying paint to improve its corrosion resistance and aesthetics. There are various types of spray coatings that can be selected according to specific requirements.
Electroplating: Coating a layer of metal or alloy on the surface of aluminum alloy to improve its corrosion resistance, hardness, and decorative properties. Common electroplating methods include galvanizing, chrome plating, nickel plating, etc.
In the surface treatment process of automotive battery cases, it is necessary to choose the appropriate surface treatment method based on the specific usage environment and requirements of the case. At the same time, it is necessary to conduct necessary testing and evaluation on the processed box to ensure that it meets the design and usage requirements.
