How to achieve liquid cooling of aluminum alloy forgings?
What are the innovations of aluminum alloy forgings for new energy vehicle battery housings?
The innovations of aluminum alloy forgings for new energy vehicle battery housings and the liquid cooling implementation technology can be deeply analyzed from the following dimensions:
I. Core innovations of aluminum alloy forgings
1. Material performance breakthroughs and process innovations
Ultra-high strength and lightweight: Using high-strength aluminum alloy forgings such as 7075 and 6061, the tensile strength is increased to 580MPa (military-grade standard) through the “three-temperature forging method” (controlling the initial forging, final forging and quenching temperature), while the density is only 1/3 of that of steel, significantly reducing the weight of the battery pack. For example, CATL uses 7 series aluminum alloy for the lower box of the battery pack, reducing the weight of the vehicle by 250 kg and increasing the cruising range to more than 600 kilometers.
Corrosion resistance and fatigue resistance optimization: Through the grain streamline directional control technology, the fatigue life of the forging is extended by 3 times, and at the same time, it still maintains a level 9 corrosion resistance after 200 hours of salt spray testing, far exceeding the industry average. Liaoyang Xiangyu Aluminum’s 4 series aluminum alloy forging bars have optimized alloy composition, yield strength>360MPa, elongation>4.5%, meeting the requirements of harsh scenarios such as chassis suspension.
2. Structural integrated design
Cooling system and shell integration: innovative design of flexible liquid pipeline integrated structure, combining the coolant water collection cavity with the bottom cavity of the shell, and flexibly adjusting the cooling area through the separation ribs to achieve precise control of the cooling position and flow. For example, a patented technology passes the coolant pipe through the cover hole and attaches the collector to both sides of the battery cell, improving the local temperature by 7°C and reducing the temperature by an average of 6.35°C.
Multi-cavity profile and wavy inner cavity: Multi-cavity wavy profile is used as the bottom plate to increase the contact area of the coolant. At the same time, through the optimization of the profile section (such as the multi-cavity opening design of the middle crossbeam), the impact resistance is maintained under the premise of reducing the weight by 15%.
3. Intelligent manufacturing process upgrade
Application of laser welding technology: Automatic laser welding equipment is used to achieve continuous welding of battery shells, reduce manual intervention and improve efficiency. For example, Fuaoxin’s patented equipment can process two shells at the same time, with high weld strength, small deformation, and IP68 sealing, which effectively prevents coolant leakage. The heat-affected zone of laser welding is only 1/5 of that of traditional welding, ensuring that the performance of aluminum alloy materials is not damaged.
Digital simulation and precision machining: Using the 3D forging simulation system to predict the metal flow state, the number of mold trials is reduced from the industry average of 5 times to 2 times, and the material utilization rate reaches 92%. At the same time, the 4000T-level die forging press cluster can produce ultra-large forgings with a diameter of 2.5 meters, and the machining allowance is reduced by 40%.
II. Implementation path of liquid cooling system
1. Cooling architecture design and fluid management
Three-dimensional heat dissipation network: Combined with liquid cooling and air cooling collaborative design, for example, the battery pack of MAZDA EZ-60 is equipped with 9 diversion holes at the bottom, using driving airflow to assist heat dissipation, and with independent serpentine liquid cooling plate (heat dissipation area increased by 20%), it forms “forced liquid cooling + natural air cooling” dual heat dissipation, so that the temperature difference of the battery cell is controlled within 5°C.
Flexible cooling pipeline layout: The water collection cavity is divided into multiple cavities, and the coolant can adjust the flow path according to demand. For example, in a patented design, the coolant flows in from a water channel interface and is transported to another water collection cavity through the coolant pipe, realizing differentiated cooling in different areas and adapting to the thermal distribution characteristics of the battery module.
2. Coolant and pump technology innovation
Low conductivity coolant: A mixture of ethylene glycol and deionized water (conductivity 200-400μs/cm) is used, with organic acid corrosion inhibitors and azole compounds added to protect aluminum alloy parts from corrosion and meet the insulation requirements in high-voltage environments (such as three-electric systems).
High-efficiency pump group and frequency conversion control: The cold plate liquid cooling system uses a high-pressure centrifugal pump (head 15-40mH₂O, flow rate 50-300L/min), and the immersion liquid cooling system uses a magnetic pump (supporting 300-800m³/h ultra-large flow rate), and dynamically adjusts the flow rate through frequency conversion technology to reduce energy consumption by more than 30%. For example, NVIDIA GPU servers achieve precise matching of coolant circulation through frequency conversion control.
3. Active thermal management and intelligent control
AI-driven dynamic adjustment: The BMS system is equipped with a dedicated AI chip, which calculates 100 times per second to adjust the strategy in real time. For example, preheating to 25℃ in winter increases the charging speed by 30%. When the temperature difference of the battery cell is detected to be greater than 5℃ in summer, the liquid cooling cycle is started within 0.01 seconds and the temperature is reduced by 10℃ within 5 seconds.
Digital twin and predictive maintenance: Optimize the design of cooling pipelines through simulation, and combine sensors to monitor the temperature, pressure and other parameters of the coolant in real time to predict potential failures. For example, a liquid cooling system reduces the failure rate by 50% through digital twin technology, and the average trouble-free operation time exceeds 50,000 hours.
III. Industry trends and application verification
Lightweight and performance balance: The aluminum alloy forging battery shell is 40%-60% lighter than the steel shell, and meets the load, drop, extrusion and other test requirements of GB/T31467.3-2015 “Lithium-ion power battery pack and system for electric vehicles”. For example, the maximum stress of a liquid-cooled aluminum alloy battery tray in the 1m drop test is 240.5MPa, which is lower than the yield strength of the material, ensuring safety.
Multi-material collaborative innovation: Some models adopt the composite structure of “aluminum alloy frame + SMC upper cover”. For example, the BYD Qin Pro EV500 uses the upper plastic and lower aluminum design to reduce the weight of the battery pack by 157kg and increase the system energy density to 160.9Wh/kg. Tesla Model Y uses an integrated die-cast aluminum alloy bracket to reduce welding points and improve rigidity.
In summary, the innovative application of aluminum alloy forgings in battery housings has achieved breakthroughs in lightweight, high strength and thermal management performance through the coordinated optimization of materials, structures and processes, combined with intelligent liquid cooling technology, providing key support for the safety and endurance improvement of new energy vehicles.
