Battery Case Forming With Differential Corner Ironing
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Solution Overview
Problem
Existing methods for manufacturing battery cases with a rectangular transverse cross-section face challenges in achieving uniform wall thicknesses and preventing wrinkling or buckling, particularly when forming stepped portions and corners, due to inconsistent ironing rates and curvature radii.
Innovation Solution
A manufacturing method involving multiple drawing and ironing steps to reduce curvature radii and adjust ironing rates individually for both sides of corners, ensuring a predetermined difference or less, to achieve targeted thicknesses and prevent wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the case body is formed by the method taught by Japanese Patent No. 4119612 to ensure wall thickness for stepped portion formation, then the stepped portion can be formed on shorter side walls, but both longer and shorter side walls become thickened, reducing case body capacity or increasing case body size
Solution Approach 1:
The patent divides the side wall ironing process into multiple stages with different ironing rates. In the first stage, both longer and shorter side walls are ironed at the same rate to ensure uniform thickness. In the second stage, only the shorter side walls are ironed at a higher rate to reduce their thickness and form stepped portions, while longer side walls maintain their thickness. This segmented approach resolves the contradiction by allowing selective thickness control.
Solution Approach 2:
The patent employs dynamic adjustment of ironing rates during the manufacturing process. The ironing rate is changed from a first rate (applied to both longer and shorter side walls) to a second rate (applied only to shorter side walls, higher than the first rate). This dynamic parameter change enables precise control over side wall thickness distribution, allowing stepped portion formation without uniform thickening of all side walls.
2Adaptability or versatility
If the curvature radius of corner is reduced shorter than predetermined radius, then the side walls can be ironed at different rates to achieve individual thickness control, but the corner geometry becomes more complex
Solution Approach 1:
The patent performs preliminary action by reducing the curvature radius of corners to a predetermined radius or less before applying different ironing rates to longer and shorter side walls. This preliminary geometric modification creates the necessary conditions for subsequent differential ironing, allowing the punch to properly support and control each side wall independently during the ironing process.
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 allows for the formation of battery cases with a rectangular cross-section without wrinkling, by homogenizing plastic flow and maintaining uniform thicknesses, thus optimizing capacity and size without increasing the case body's dimensions.
Implementation Method 1
shaping the intermediate product into the case body as a final product having a rectangular transverse cross-section by drawing and ironing the intermediate product multiple times to reduce a curvature radius of each corner and thicknesses of side walls
Data Source
AI summary
A manufacturing method of a battery case having a rectangular transverse cross-section in which an intermediate product having an elliptical transverse cross-section is shaped into a final product having a rectangular transverse cross-section by drawing and ironing the intermediate product multiple times to reduce a curvature radius of each corner and thicknesses of side walls formed on both sides of the corner. A difference between an ironing rate of the side wall formed on one side of the corner and an ironing rate of the side wall formed on the other side of the corner is reduced less than a predetermined difference, after the curvature radius of the corner between the side walls has been reduced shorter than a predetermined radius during the process of shaping the intermediate product into the final product.