Battery Cap Assembly Vent Welding for Porosity-Resistant Sealing
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Solution Overview
Problem
Laser welding in cap assembly manufacturing for secondary batteries can result in porosity, leading to weak welding portions that are prone to separation under external impacts.
Innovation Solution
A cap assembly design featuring a vent that deforms under pressure, with a cap-up and cap-down configuration, and multiple welding marks that intersect at least three times with an imaginary straight line, ensuring strong bonding between the cap-up and vent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is used to secure the vent and cap-up, then manufacturing efficiency is improved, but porosity forms in the welding portion reducing its strength
Solution Approach 1:
The patent applies parameter changes by modifying the laser welding parameters including power, speed, and focus position to optimize the welding process. By adjusting these parameters, the patent achieves complete penetration welding without porosity formation, thereby maintaining both high manufacturing efficiency and welding portion strength
Solution Approach 2:
The patent employs periodic action through multi-pass welding where the laser welding is performed in multiple sequential passes. Each pass deposits weld metal and allows for proper cooling and solidification, preventing porosity accumulation while maintaining production efficiency through optimized cycle timing
2Strength
If welding power is increased to prevent porosity, then welding portion strength is improved, but deformation of the cap-up increases
Solution Approach 1:
The patent applies segmentation by dividing the welding process into multiple passes rather than attempting to complete the weld in a single high-power pass. This segmentation allows the heat input to be distributed over time and space, achieving strong welds without excessive localized heating that would cause cap-up deformation
Solution Approach 2:
The patent employs dynamics by using a movable laser source that travels along the weld joint with controlled speed and trajectory. This dynamic welding approach, combined with real-time parameter adjustment, enables precise heat control that prevents both porosity and deformation by adapting the welding conditions to the specific local requirements of the joint
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 enhances the strength and integrity of the welding portion, preventing separation due to external impacts and ensuring reliable sealing of the secondary battery.
Implementation Method 1
laser welding may be employed to secure a safety vent and a cap-up
Implementation Method 2
a breakable portion that may be fractured by a pressure of a gas delivered through the plurality of through holes
Data Source
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AI summary
A cap assembly (300) includes a vent (320) deformable in response to a change in pressure, a cap-up (330) on the vent and connectable to an external terminal, the vent (320) surrounding a portion of an upper surface and a side surface of an outer edge of the cap-up (330), a cap-down (310) that is below the vent (320), and a plurality of welding marks (360) at a plurality of points on a portion of the vent (320) arranged on the portion of the upper surface of the outer edge of the cap-up (330), wherein each of the plurality of welding marks (360) intersects at least three times with an imaginary straight line (370) in a region where the upper surface of the outer edge of the cap-up (330) and the vent (320) come into contact, and wherein the imaginary straight line (370) is horizontal with respect to a boundary surface between the upper surface of the outer edge of the cap-up (330) and the vent (320).