Battery Pouch Bridge Geometry for Crack-Resistant Cup Molding
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Solution Overview
Problem
Existing secondary battery pouch manufacturing processes face challenges in reducing the width of the pouch bridge while minimizing pressure, leading to increased crack probability and surface defects.
Innovation Solution
A manufacturing apparatus with a lower die, punch, and stripper design that includes accommodation grooves connected by a bridge part with straight lateral sides and a curved top portion, where the height of the top portion is less than half the width of the pillar, to relieve pressure on the pouch bridge during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of the pouch bridge portion is reduced to decrease space loss in battery pack, then the space utilization is improved, but the pressure applied to the pouch bridge molding part increases leading to cracks on pouch surface
Solution Approach 1:
The invention applies local quality by creating a bridge part with non-uniform cross-section, where the upper end has a smaller width than the lower end. This localized variation in geometry allows the bridge to better distribute molding pressure, preventing cracks while maintaining reduced overall width for space efficiency.
Solution Approach 2:
The invention employs curvature by forming the bridge part with a tapered, curved transition from the wider lower end to the narrower upper end. This curved geometry distributes stress more evenly compared to a straight, abrupt transition, reducing the likelihood of crack formation during molding.
2Productivity
If the width of the pouch bridge portion is reduced to improve space efficiency, then the battery pack density is improved, but the probability of occurrence of cracks on pouch bridge surface increases
Solution Approach 1:
The bridge part features local quality through its tapered design, where the cross-sectional width varies along its length. The upper end is narrower to save space while the lower end is wider to provide structural support and reduce stress concentration, thus maintaining both productivity and reliability.
Solution Approach 2:
The invention applies parameter changes by varying the width parameter of the bridge part along its height. The width transitions from a larger value at the lower end to a smaller value at the upper end, optimizing both space utilization and mechanical strength to prevent cracks.
3Volume of moving object
If the pouch bridge width is minimized to reduce space loss, then the volume efficiency is improved, but the pressure concentration on the bridge molding part increases
Solution Approach 1:
The bridge part is designed with local quality through its tapered geometry, where the cross-sectional area varies along its length. This creates regions of different stress distribution, with the wider lower end bearing more load and the narrower upper end fitting tighter spaces, thus reducing overall pressure concentration.
Solution Approach 2:
The curved, tapered shape of the bridge part helps distribute molding pressure more evenly by avoiding sharp corners and abrupt transitions. The gradual curvature allows stress to flow smoothly through the structure, reducing pressure concentration points that would lead to cracking.
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The present invention relates to an apparatus for manufacturing a pouch of a secondary battery and a pouch of a secondary battery, which is manufactured by the apparatus, and more particularly, to an apparatus for manufacturing a pouch of a secondary battery, in which, when the pouch having two cup parts is molded, the pouch is molded by relieving a pressure applied to a pouch bridge that is a narrow connection part between the two cup parts to improve quality of a finally molded pouch product, and a pouch of a secondary battery manufactured by the method. An apparatus for manufacturing a pouch of a secondary battery includes: a lower die having an accommodation groove for molding a cup part of the pouch in a base surface, on which the pouch is disposed; a punch inserted into the accommodation groove of the lower die to mold the cup part of the pouch; and a stripper provided to press a peripheral part of the pouch, which is disposed around a portion to be molded as the cup part of the pouch by the punch, wherein two accommodation grooves provided with a left accommodation groove and a right accommodation groove are formed in the lower die, a bridge part configured to connect the two accommodation grooves to each other is formed between the left accommodation groove and the right accommodation groove, the bridge part includes a pillar portion of which lateral sides are formed as two straight lines and a top portion formed as a curve on an upper end of the pillar portion, based on a cross-sectional view, and a height (h) of the top portion, which is measured at an upper end of the pillar portion, is less than 1/2 of a width (W) of the pillar portion.