Split Mandrel Joint Structure for Low-Deformation Battery Winding
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Solution Overview
Problem
Existing mandrels for manufacturing cylindrical secondary battery electrode assemblies deform excessively when their caliber is reduced, leading to mechanical property deterioration and increased strain rates, which can result in damage during the winding process.
Innovation Solution
A mandrel design featuring first and second mandrel members with semicircular cross-sections, inclined joint surfaces, and concave-convex parts, including protrusions and grooves, to minimize deformation. The concave-convex parts are formed on specific joint surfaces to engage with each other, reducing strain rates and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diameter of the mandrel is decreased to increase battery capacity, then the battery capacity increases, but the mechanical properties deteriorate and strain rate increases
Solution Approach 1:
The mandrel is divided into two separate mandrel members that are coupled together. This segmentation allows each member to be optimized for strength while maintaining a smaller overall diameter, resolving the contradiction between increased battery capacity (smaller diameter) and maintained mechanical properties.
Solution Approach 2:
The two mandrel members are designed with asymmetric structures having different cross-sectional areas. This asymmetric design optimizes the stress distribution and mechanical strength of each member, allowing the mandrel to maintain adequate strength even when the overall diameter is reduced for higher battery capacity.
2Quantity of substance
If the diameter of the mandrel is decreased to increase battery capacity, then the battery capacity increases, but the strain rate increases causing damage risk
Solution Approach 1:
Dividing the mandrel into two members reduces the strain rate on each individual member compared to a single small-diameter mandrel, thereby maintaining reliability and reducing damage risk while enabling smaller diameter for higher capacity.
Solution Approach 2:
The invention changes the structural parameters of the mandrel by using two members with specific cross-sectional area ratios. This parameter optimization controls the strain rate within acceptable limits while maintaining the smaller diameter needed for higher battery capacity.
3Stability of the object's composition
If the mandrel members are designed asymmetrically to prevent deformation, then the deformation is reduced, but the manufacturing complexity increases
Solution Approach 1:
The mandrel members are designed with asymmetric cross-sections optimized to minimize deformation during operation. While this increases design complexity, the asymmetric structure is achieved through standard manufacturing processes, balancing deformation control with manufacturability.
Data Source
AI summary
A mandrel for manufacturing an electrode assembly includes a first mandrel member having a semicircular cross-section and a predetermined length, and a second mandrel member configured to define a cylindrical shape of the mandrel by being coupled to the first mandrel member while facing the first mandrel member. A concave-convex part is provided on joint surfaces of the first and second mandrel members. The concave-convex part includes a protrusion and a groove formed in a longitudinal direction so as to engage with each other.