Sealed Battery Welding With Orthogonal Bottom Surface
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Solution Overview
Problem
Existing sealed battery technologies face challenges in ensuring stable joint strength between the battery case and sealing member due to variations in manufacturing processes and the risk of foreign matter entry and void formation during welding, which can lead to reduced weld quality and potential internal shorts.
Innovation Solution
A sealed battery design featuring a weld portion with a weld bottom surface orthogonal to the depth direction, extending to the outer surface of the second member, and a specific ratio of weld depth to distance from the weld bottom surface, ensuring stable weld length and area, thereby reducing fracturing and foreign matter entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high output, high convergence laser welding is used to increase weld depth, then weld strength at the butt portion is improved, but weld quality deteriorates due to excessive melting causing voids and foreign matter entry
Solution Approach 1:
The patent changes the welding parameters by using multiple laser beams with different outputs instead of a single high-output laser. The first laser beam has higher output for deep penetration, while the second laser beam has lower output to prevent excessive melting. This parameter differentiation allows achieving both deep weld penetration and controlled melting to avoid voids and spatter.
Solution Approach 2:
The patent segments the welding process by using multiple independent laser beams (first and second laser beams) instead of a single laser beam. Each laser beam contributes differently to the welding process - the first provides deep penetration while the second controls the surface melting. This segmentation allows independent optimization of different welding requirements.
2Strength
If weld depth is increased to ensure sufficient joint strength, then weld strength is improved, but the risk of foreign matter entry and void formation increases
Solution Approach 1:
The patent uses two laser beams with different output parameters to achieve controlled weld depth. The first laser beam with higher output creates sufficient penetration for strong joints, while the second laser beam with lower output limits excessive melting that would cause voids and spatter. This dual-parameter approach simultaneously achieves both goals.
Solution Approach 2:
The patent converts the potentially harmful effect of excessive melting into a beneficial controlled process. By using the second lower-output laser beam, the excessive melting that would normally cause voids and spatter is converted into controlled surface melting that maintains joint strength while preventing defects.
3Manufacturing precision
If welding position varies due to manufacturing process variations, then weld depth becomes insufficient, but increasing laser output to compensate causes excessive melting and quality issues
Solution Approach 1:
The patent uses multiple laser beams with different outputs to create a welding process that is less sensitive to position variations. The combined heat input from multiple beams with different characteristics provides more stable and consistent weld depth even when positioning varies, while the lower-output beam prevents excessive melting that would compromise quality.
Solution Approach 2:
The patent provides a cushioning effect against positioning variations by using the second lower-output laser beam. This beam acts as a buffer that prevents the welding process from becoming too sensitive to position variations, ensuring consistent weld quality even when the first higher-output beam's penetration varies due to positioning errors.
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 design stabilizes weld strength and reduces fracturing at the boundary between weld and non-weld portions, ensuring reliable sealing and preventing internal defects like voids and foreign matter entry, even with variations in manufacturing processes.
Implementation Method 1
joining the sealing plate to the case main body by a weld portion that includes a portion of a boundary surface of the case main body and the sealing plate, and the weld portion being provided along the boundary surface
Data Source
AI summary
A sealed battery includes: a case main body that has an opening; and a sealing plate that closes off the opening, the sealing plate being joined to the case main body by a weld portion. The weld portion includes a weld bottom surface intersecting with the boundary surface of the case main body and the sealing plane, and the weld bottom surface being substantially orthogonal to the depth direction. A depth of the weld portion on a first virtual plane including the boundary surface, is greater than the depth of the weld portion on a second virtual plane including an outer surface of the case main body, the outer surface being opposite side from the boundary surface in the thickness direction of the case main body.