Rotary Blade Surface Roughness for Battery Separator Cutting
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Solution Overview
Problem
Cutting apparatuses for lithium-ion secondary battery electrode sheets face issues with defective cutting due to the separator made of resin flowing into the clearance between rotary blades, leading to increased friction and wear, which affects the cutting quality and longevity of the blades.
Innovation Solution
The cutting apparatus employs a disk-shaped rotary blade with a rough surface portion and a smooth surface portion, where the rough surface portion has an arithmetical mean roughness greater than 0.5 and is formed by a blasting process, and the smooth surface portion has an arithmetical mean roughness less than 0.2, optionally coated with a diamond-like carbon film, to prevent foreign objects from adhering and ensure appropriate clearance for smooth cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clearance is provided between two rotary blades to prolong blade life and reduce friction, then the robustness and tolerance for clearance variations improve, but the separator made of resin flows into the clearance causing defective cutting
Solution Approach 1:
The invention applies different surface qualities to different regions of the rotary blade. The circumferential edge portion (cutting region) has a rough surface with arithmetical mean roughness of 0.5 μm or more to prevent separator flow, while other portions have smoother surfaces. This local differentiation allows the blade to maintain both robustness through clearance and cutting precision through controlled separator interaction at the cutting edge.
2Manufacturing precision
If the clearance between rotary blades is set narrow to improve cutting precision, then cutting quality improves, but the rotary blades experience increased friction and wear reducing their longevity
Solution Approach 1:
The rough surface is applied specifically to the circumferential edge portion where cutting occurs, while other portions of the blade maintain smoother surfaces. This localized treatment allows narrow clearance for precision cutting without excessive friction and wear across the entire blade surface, thereby extending blade life while maintaining cutting quality.
3Duration of action of stationary object
If the clearance between rotary blades is set wide to reduce friction and prolong blade life, then blade longevity improves, but the separator flows into the clearance causing defective cutting
Solution Approach 1:
By making only the circumferential edge portion rough while keeping other blade portions smooth, the invention enables wider clearance settings that reduce overall friction and prolong blade life, while the rough edge portion specifically prevents separator flow into the clearance during cutting, maintaining cutting quality.
4Manufacturing precision
If a rough surface is applied to the circumferential edge portion to prevent separator flow, then cutting quality improves, but foreign objects may adhere to the rough surface
Solution Approach 1:
The rough surface is applied only to the circumferential edge portion where cutting occurs, minimizing the total surface area that can accumulate foreign objects. The rest of the blade maintains smoother surfaces that are less prone to adhesion, thereby balancing cutting quality improvement with reduced foreign object adhesion.
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 solution effectively prevents defective cutting by ensuring the rotary blades adequately catch the separators, reducing adhesion of cuttings, and allowing for a wider tolerance in clearance variations, thereby enhancing the cutting robustness and longevity of the blades.
Implementation Method 1
the rough surface portion having a predetermined width from a blade edge of the respective circumferential edge portion and having an arithmetical mean roughness of greater than 0.5
Implementation Method 2
the smooth surface portion provided radially inward of the rough surface portion and having an arithmetical mean roughness less than the arithmetical mean roughness of the rough surface portion
Data Source
AI summary
Each of a first rotary blade and a second rotary blade includes a rough surface portion and a smooth surface portion. The rough surface portion has a predetermined width from a blade edge at its circumferential edge portion and has an arithmetical mean roughness of greater than 0.5. The smooth surface portion is provided radially inward of the rough surface portion and has an arithmetical mean roughness less than the arithmetical mean roughness of the rough surface portion.