Sealed Battery Laser Welding to Prevent Voids at the Cover Joint
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Solution Overview
Problem
Existing methods for producing sealed batteries face issues with voids and insufficient weld strength due to the presence of electrolytic solution and oil on the welding area, leading to incomplete joining of the battery case and sealing cover.
Innovation Solution
A laser beam profile is used to vaporize the electrolytic solution and oil on the welding surface before performing keyhole welding, ensuring a firm join by using a first beam for vaporization and a second beam for keyhole welding on the cleaned surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If keyhole welding is performed on the welding area with electrolytic solution and oil present, then welding speed is improved, but voids are generated and weld strength is reduced
Solution Approach 1:
The patent applies preliminary action by performing heat-conduction welding before keyhole welding. The heat-conduction welding step pre-heats the welding area and removes electrolytic solution and oil residues, creating a clean surface for subsequent keyhole welding. This preliminary preparation prevents void formation while maintaining high welding speed and strength in the final keyhole welding process.
2Length of stationary object
If keyhole welding is performed first to achieve deep penetration, then weld depth is improved, but voids are generated due to electrolytic solution and oil vaporization
Solution Approach 1:
The patent performs heat-conduction welding as a preliminary step before keyhole welding. This preliminary action removes electrolytic solution and oil from the welding area through controlled heating, preventing these substances from vaporizing during subsequent keyhole welding and forming voids. The penetration depth is then achieved in the second keyhole welding step without void formation.
3Reliability
If heat-conduction welding is used to avoid voids, then weld quality is improved, but penetration depth is insufficient and weld strength is reduced
Solution Approach 1:
The patent merges two welding methods into a sequential process: heat-conduction welding followed by keyhole welding. The heat-conduction welding provides controlled heating and contaminant removal, while the subsequent keyhole welding achieves deep penetration. By combining these two methods in sequence, the patent obtains both high weld quality and sufficient penetration depth.
Solution Approach 2:
Heat-conduction welding serves as a preliminary action that prepares the welding area by removing contaminants and pre-heating the materials. This preparation enables the subsequent keyhole welding to achieve deep penetration without void formation, as the harmful substances have already been eliminated in the preliminary heating step.
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
This method reduces voids and achieves a deep weld, firmly joining the battery case and sealing cover, enhancing the structural integrity of the sealed battery.
Implementation Method 1
a first beam capable of vaporizing the electrolytic solution and oil, which exist on a surface of the welding area
Implementation Method 2
a second beam enabling keyhole welding on a removal portion of the welding area
Data Source
AI summary
A method for producing a sealed battery, capable of firmly joining a battery case and a sealing cover, includes injecting an electrolytic solution into the battery case through the liquid inlet, and after the injecting, welding the battery case and the sealing cover by irradiating and linearly scanning a laser beam on a welding area across the battery case and the sealing cover, while the liquid inlet is closed with the sealing cover. The laser beam has a beam profile including a first beam capable of vaporizing the electrolytic solution and oil, which exist on the surface of the welding area, and a second beam enabling keyhole welding on a removal portion of the welding area, from which at least part of the electrolytic solution and at least part of the oil have been removed by irradiation of the first beam.