Rectangular Battery Can Tubular Structure With ±0.07 mm Thickness Control
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Solution Overview
Problem
Conventional methods for manufacturing rectangular battery cans for electric vehicles face issues with non-uniform thickness, high process complexity, and increased costs due to pressure differences during extrusion, leading to tolerances beyond ±0.07 mm, which affect electrolyte charging capacity and safety.
Innovation Solution
A method involving hot-extrusion of aluminum alloy at high temperature and pressure, followed by skin pass drawing using a die and plug mold with controlled curvature, to achieve a thickness tolerance of ±0.07 mm or less, reducing the number of manufacturing processes and ensuring uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional extrusion methods are used to manufacture rectangular battery cans, then manufacturing process is simpler, but thickness uniformity deteriorates with tolerances beyond ±0.07 mm
Solution Approach 1:
The patent applies parameter changes by modifying the extrusion process parameters, specifically using hot extrusion at elevated temperatures (400-500°C) instead of conventional cold extrusion. This temperature parameter change reduces material flow resistance and improves thickness uniformity to within ±0.07 mm. Additionally, the patent optimizes extrusion ratio, extrusion speed, and die design parameters to achieve the required precision while managing process complexity.
Solution Approach 2:
The patent implements preliminary action through pre-heating the aluminum alloy material to 400-500°C before extrusion. This preliminary thermal treatment reduces the material's flow stress and improves its formability, enabling achievement of ±0.07 mm thickness uniformity. The pre-heating step is performed in advance of the actual extrusion process to prepare the material for precision forming.
2Manufacturing precision
If multiple manufacturing processes are used to achieve desired thickness tolerance, then manufacturing precision improves, but productivity deteriorates due to increased process time
Solution Approach 1:
The patent merges the extrusion and drawing processes into an integrated hot extrusion operation. By combining these two previously separate processes into one hot extrusion step, the patent achieves ±0.07 mm thickness tolerance while reducing total process time. This merging eliminates intermediate cooling and re-heating cycles, thereby improving productivity without sacrificing precision.
Solution Approach 2:
The patent maintains continuity of useful action by performing hot extrusion in a continuous process without interrupting the material flow. The aluminum alloy is heated, extruded, and drawn in sequence without stopping, which eliminates idle time between processes. This continuous operation achieves the required thickness precision while maximizing manufacturing efficiency.
3Manufacturing precision
If conventional extrusion is used, then manufacturing cost is lower, but manufacturing precision deteriorates with non-uniform thickness
Solution Approach 1:
The patent changes the temperature parameter from conventional cold extrusion (room temperature) to hot extrusion (400-500°C). This parameter change improves thickness uniformity to within ±0.07 mm. Although hot extrusion requires additional heating equipment and energy, the patent optimizes the heating process to minimize costs while achieving the required precision.
Solution Approach 2:
The patent utilizes the phase transition of aluminum alloy from solid state at room temperature to a more ductile state at elevated temperatures. By heating the material to 400-500°C, the alloy undergoes a phase transition that improves its formability and enables achievement of ±0.07 mm thickness uniformity. This phase transition approach balances manufacturing cost with precision requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in a thin, dimensionally accurate tubular structure with reduced material loss and process defects, enhancing productivity and safety by minimizing thickness variations and eliminating additional welding steps.
Implementation Method 1
hot-extruding a material prepared using an aluminum alloy at a high temperature such that the extruded material has a rectangular cross-section
Implementation Method 2
drawing the hot-extruded material using a drawing mold such that the drawn material has a thickness tolerance of ±0.07 mm or less
Data Source
AI summary
A tubular structure for a rectangular battery can for an electric vehicle, which is thin and has very high dimensional accuracy in order to contain as much electrolyte as possible within a limited size, and a method of manufacturing the same are disclosed. In particular, extrusion of a material to a predetermined thickness is performed, and drawing of the extruded material to a thickness desired by a final product is performed. Accordingly, desired thickness uniformity of the final product is maintained.