Pouch Case Forming with Two-Stage Stretch Dispersion
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Solution Overview
Problem
Conventional forming processes for pouch-type battery cases result in low residual rates and potential cracks due to concentrated stretching at corners, leading to electrolyte leakage and decreased insulation resistance.
Innovation Solution
A forming apparatus and method that divides the pressing process into primary and secondary stages, utilizing a die with protrusions and recesses, and a punch, to disperse stretching and increase residual rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a punch press is performed with a fixed punch and stripper to form the pouch case, then the forming process can be completed, but stretching is concentrated at corners and corner edges resulting in low residual rate
Solution Approach 1:
The forming process is divided into two distinct stages: a first forming process that forms the cup shape, and a second forming process that forms the side seal. This segmentation allows each process to be optimized independently, preventing concentrated stretching in the corners while maintaining overall forming efficiency.
Solution Approach 2:
The first forming process is performed as a preliminary action to create the cup shape before the second forming process seals the side. By preparing the cup shape in advance, the material distribution is optimized before the final sealing operation, preventing excessive stretching and thinning at critical locations.
2Ease of manufacture
If the punch is in contact with the pouch to perform forming, then the forming can be achieved, but stretching is mainly performed at corner and corner edge resulting in low residual rate
Solution Approach 1:
The forming operation is segmented into two separate processes with different tool configurations. The first process uses a punch and die to form the cup, while the second process uses different tools to seal the side. This segmentation ensures that each operation maintains appropriate contact and control without causing excessive localized stretching.
Solution Approach 2:
The forming parameters are changed between the two processes. The first forming process uses specific pressure and contact conditions to create the cup shape, while the second process uses different parameters optimized for side sealing. This parameter optimization prevents excessive stretching and maintains high residual rate.
3Productivity
If concentrated stretching occurs at corner and corner edge, then forming can be completed, but cracks may occur causing electrolyte leakage and decreased insulation resistance
Solution Approach 1:
By dividing the forming into two processes, the stress and stretching are distributed across different operations rather than concentrated in a single process. This prevents the material from experiencing excessive localized deformation that would lead to cracking and subsequent electrolyte leakage.
Solution Approach 2:
The cup shape is formed in advance as a preliminary step, which properly distributes the material before the side sealing operation. This preliminary forming action prevents concentration of stretching at corners during the final sealing process, eliminating the root cause of cracks and electrolyte leakage.
Data Source
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AI summary
A forming apparatus according to the present invention includes a die having a top surface provided to press an object to be pressed, a stripper disposed to face the die so as to press the object to be pressed, and a punch provided inside the stripper to press the object to be pressed, wherein the die includes a protrusion disposed at the innermost side of the top surface that presses the object to be pressed.