Laser Weld Defect Detection Using Thermal and Plasma Light
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Solution Overview
Problem
Existing laser welding quality inspection methods struggle to accurately detect minute welding abnormalities due to overlapping signal intensities of thermal radiation and plasma light, leading to erroneous determinations.
Innovation Solution
A method and apparatus that compare the signal intensities of thermal radiation light and plasma light during laser welding to determine welding abnormalities by calculating a difference signal between the two, using normalization and setting a determination reference value for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the peak intensity or integrated intensity of welding light (thermal radiation light, plasma light, and laser reflection light) is used for defect determination, then clear welding abnormalities can be detected, but minute welding abnormalities cannot be accurately determined
Solution Approach 1:
The patent segments the welding light into three distinct components: thermal radiation light, plasma light, and laser reflection light. By using multiple light-receiving units that separately detect each component, the system can analyze the characteristics of each light type independently. This segmentation allows for more precise identification of minute welding abnormalities by comparing the specific patterns and intensity ratios of different light components, thereby improving both measurement precision and determination reliability.
2Loss of information
If multiple types of welding light signals are combined for analysis, then comprehensive welding state information is obtained, but signal overlap reduces detection accuracy for minute defects
Solution Approach 1:
The patent applies local quality by assigning different analysis methods to different light components based on their specific characteristics. Thermal radiation light is analyzed for its intensity pattern over time, plasma light is analyzed for its spectral characteristics, and laser reflection light is analyzed for its intensity fluctuations. By tailoring the analysis approach to each light type's local properties, the system maintains complete welding state information while avoiding signal overlap interference, thus improving minute defect detection precision.
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
Enhances the accuracy of welding abnormality detection by distinguishing minute defects through the differential analysis of thermal radiation and plasma light signals, reducing erroneous determinations.
Implementation Method 1
acquiring first data indicating a signal intensity of thermal radiation light radiated from the welded portion during the welding
Implementation Method 2
when the joining object and the joined object are welded by being irradiated with a laser beam
Data Source
AI summary
A laser welding quality inspection method of a welded portion between a joining object and a joined object, when the joining object and the joined object are welded by being irradiated with a laser beam, the method includes: acquiring first data indicating a signal intensity of thermal radiation light radiated from the welded portion during the welding; acquiring second data indicating a signal intensity of plasma light radiated from the welded portion during the welding; and determining whether or not the welded portion includes an abnormality based on a comparison between the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired.