Laser Weld Focus Adjustment for Battery Tab Penetration Control
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Solution Overview
Problem
The challenge in laser welding busbar connections to cell terminals arises from uncertainties in positioning due to small material depths and differing laser energy absorption properties, leading to potential over or under penetration, which can result in welding failure, equipment damage, and safety hazards.
Innovation Solution
A laser welding process that measures the first axis position of connection tabs and cell terminals to determine the appropriate focus distance for the welding laser beam, allowing for accurate alignment and penetration, even with materials of varying absorption rates and positional inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed through connection tabs with small material depths, then welding speed and productivity are improved, but the risk of over or under penetration increases due to fine margins and positioning uncertainty
Solution Approach 1:
The system performs preliminary measurement of the connection tab position and material depth before welding. The measuring device captures the actual position of the connection tab relative to the cell terminal, and this measurement is used to pre-calculate the optimal focus distance for the laser beam, ensuring accurate penetration control before the welding process begins
Solution Approach 2:
The system dynamically adjusts the focus distance of the laser beam based on real-time measurements of connection tab position. The focus distance is not fixed but is continuously adapted to match the actual positioning variations of each connection tab, allowing the system to maintain precise welding control despite positioning uncertainties
2Productivity
If materials with high laser energy absorption are used for connection tabs and cell terminals, then welding speed is improved, but the likelihood of over penetration and welding defects increases
Solution Approach 1:
The system pre-determines the optimal focus distance by measuring the actual position and material depth of the connection tab before welding. This preliminary calculation accounts for the high absorption properties of the materials, allowing the laser parameters to be optimized in advance to achieve complete penetration without over penetration
Solution Approach 2:
The system changes the focus distance parameter of the laser beam based on measured positioning variations. By adjusting the focus distance rather than maintaining a fixed focus, the system adapts the laser energy distribution to match the actual material geometry and absorption characteristics, preventing both under and over penetration
3Manufacturing precision
If accurate positioning of cells and connection tabs is assumed for laser welding, then welding precision is improved, but the system becomes vulnerable to positioning errors and variations in cell dimensions
Solution Approach 1:
The system implements a feedback mechanism where the actual position of each connection tab is measured before welding, and this measurement feedback is used to adjust the focus distance for that specific connection. This closed-loop approach compensates for positioning errors and dimensional variations, making the welding process robust against manufacturing tolerances
Solution Approach 2:
The system performs preliminary measurement and calculation of the optimal focus distance for each connection tab before the actual welding operation. This pre-positioning compensation ensures that even if cells or connection tabs have positioning variations or dimensional differences, the welding parameters are already optimized for the actual configuration
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 process enhances the accuracy of laser welding by accounting for positional inaccuracies and varying material properties, reducing the risk of over or under penetration and ensuring safer, more reliable welds.
Implementation Method 1
a measuring step comprising obtaining measurements indicative of a first axis position of each of the connection tabs
Implementation Method 2
each joining is performed using a welding laser beam
Implementation Method 3
the materials used for one, other or both of the connection tab and cell terminal may be primarily selected for reasons other than their laser welding properties
Implementation Method 4
the materials used for one, other or both of the connection tab and cell terminal may be primarily selected for reasons other than their laser welding properties and may for instance be relatively highly absorbing of the laser energy
Data Source
AI summary
A laser welding process arranged to join each of a plurality of connection tabs to a respective one of a plurality of terminals comprises: a positioning step which sets in space, with respect to a first axis, respective positions of each connection tab and cell terminal; a measuring step comprising obtaining measurements indicative of the first axis position of each connection tab; and a welding step comprising determining, in accordance with the measurements, a respective focus distance to be used for the welding laser beam in joining each of the connection tabs to its respective cell terminal and, using the relevant respective laser beam focus distance determined, welding, in turn, each connection tab to its respective cell terminal.