Pouch Cell Tab-to-Lead Weld Inspection by Vision Trace Measurement
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Solution Overview
Problem
Existing methods for inspecting the welding quality of electrode tab-electrode lead connections in lithium secondary batteries are destructive and provide unreliable results due to limited inspection areas, necessitating a non-destructive and more reliable method.
Innovation Solution
A non-destructive inspection method using a vision inspection device to recognize welding traces, measure their sizes, and compare them with reference values to determine if the welds are weak, excessive, or normal, utilizing ultrasonic or laser welding methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tensile strength measurement by pulling electrode tab and electrode lead is used, then welding quality can be determined, but the inspection method becomes destructive and total inspection is impossible
Solution Approach 1:
The patent replaces the mechanical tensile strength measurement system with an optical vision inspection system. Instead of physically pulling the electrode tab and electrode lead to measure welding quality, the system uses a vision device to capture images of the welded portion and analyzes welding trace characteristics (length, width, area) to determine welding quality. This substitution eliminates the destructive nature of the inspection while maintaining reliability.
Solution Approach 2:
The patent creates an optical copy (image) of the welded portion instead of physically testing the actual weld. The vision device captures an image of the welding trace, and the welding quality is determined by analyzing the characteristics of this optical copy. This allows non-destructive inspection while maintaining the ability to assess welding quality accurately.
2Productivity
If vision inspection with limited pressure points is used, then non-destructive inspection is achieved, but reliability decreases due to limited inspection area
Solution Approach 1:
The patent segments the welding trace into multiple characteristic parameters for analysis. Instead of inspecting the entire welded area as a single unit, the system divides the welding trace measurement into multiple dimensions including length, width, and area calculations. This segmentation allows comprehensive analysis of the welding quality from a single full-area image, improving reliability without requiring multiple inspection points.
Solution Approach 2:
The patent transitions from point-based inspection to area-based inspection by capturing and analyzing the two-dimensional characteristics of the welding trace. The vision device captures the entire welded portion in an image, and the system analyzes dimensional parameters (length, width, area) of the welding trace. This dimensional transformation from zero-dimensional point inspection to two-dimensional area inspection significantly improves reliability while maintaining non-destructive capability.
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
Enables accurate and comprehensive welding quality assessment without damaging the batteries, allowing all welds to be inspected, and supplementing with tensile strength testing for confirmation.
Implementation Method 1
recognizing welding traces of the welded portion by a vision inspection device
Implementation Method 2
the ultrasonic welding is a scheme which generates ultrasonic vibrations of 10 to 75 kHz and welds metal through ultrasonic vibration friction heat between metals
Implementation Method 3
friction heat is generated on the contact surface between the electrode tab and the electrode lead, and the electrode tab and the electrode lead are welded by the generated friction heat
Implementation Method 4
When the electrode tab and the electrode lead are welded, laser welding, resistance welding and ultrasonic welding may be used
Data Source
AI summary
The present invention relates to a method for inspecting a welding quality of an electrode tab-electrode lead welded portion of a pouch-type lithium secondary battery, and the method includes: recognizing welding traces of the welded portion by a vision inspection device; measuring a size of each of the recognized welding traces; and determining whether the welded portion has been weakly welded, excessively welded or normally welded by comparing the measured size with a reference value.