Oval Mandrel Segmentation for Jelly Roll Winding Stress Reduction
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Solution Overview
Problem
Conventional mandrels used in manufacturing jelly roll type electrode assemblies experience high linear velocity changes and increased stress at the folded portions, leading to residual stress and potential breakage, which compromises battery safety and efficiency.
Innovation Solution
A mandrel with an oval section perpendicular to its rotational axis, divided into a first and second mandrel part, each with a main body and an exchange part, allowing for easy exchange of the exchange part when the electrode assembly standard changes, reducing manufacturing time and stress on the sheet type stack by minimizing linear velocity change and force concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional mandrel with a single metal structure is used, then the mandrel is simple in structure and easy to manufacture, but the linear velocity changes significantly during rotation causing high stress concentration at the folded portion of the sheet type stack
Solution Approach 1:
The mandrel is divided into two separate mandrel parts (first mandrel part and second mandrel part) that can be independently adjusted. This segmentation allows each part to be optimized for reducing linear velocity changes at their respective folded portions, thereby reducing stress concentration while maintaining structural simplicity through modular design.
2Ease of manufacture
If the mandrel is made as a single integrated piece, then manufacturing is simple, but the entire mandrel must be replaced when electrode assembly standards change, increasing manufacturing time and cost
Solution Approach 1:
The mandrel is segmented into a body part and interchangeable end parts (first end part and second end part). The end parts can be detached and replaced independently when electrode assembly standards change, while the body part remains. This significantly reduces replacement time and cost compared to replacing the entire mandrel, while maintaining ease of manufacture through modular assembly.
Solution Approach 2:
The mandrel design incorporates adjustable and interchangeable components that allow dynamic adaptation to different electrode assembly standards. The end parts can be swapped out to match different specifications, making the mandrel system flexible and adaptable without requiring complete replacement.
3Ease of manufacture
If a conventional mandrel design is used, then manufacturing cost is lower, but the folded portion of the sheet type stack experiences high impact and residual stress leading to breakage
Solution Approach 1:
By dividing the mandrel into separate parts with independently adjustable geometry, each mandrel part can be optimized to minimize linear velocity changes at the folded portions. This reduces impact forces and residual stress on the sheet type stack during winding, preventing breakage while keeping manufacturing costs reasonable through selective replacement of only the end parts.
Data Source
AI summary
Disclosed herein is a mandrel configured to be used in a winding process for manufacturing a jelly roll type electrode assembly using a long sheet type stack of a cathode/separator/anode structure, wherein the mandrel is oval in a section perpendicular to a rotational central axis of the mandrel and is divided into a first mandrel part located at one side of a central region of the mandrel, in which an end of the sheet type stack is fixedly fitted, and a second mandrel part located at the other side of the central region of the mandrel, and the first mandrel part and the second mandrel part each include a main body part having a region in which the sheet type stack is fitted in an engaged state and an exchange part, detachably mounted to the main body part, having an end of a major axis of the mandrel.