Molten Pool Oscillation Monitoring for Laser Weld Hot Cracks
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Solution Overview
Problem
Current methods for detecting hot cracks in laser-welded workpieces are time-consuming and labor-intensive, requiring post-welding preparation and specialized equipment, which hinders efficient quality assessment and real-time monitoring of weld seam quality.
Innovation Solution
Monitoring the parameters of molten bath oscillations during laser beam welding, such as amplitude and frequency, to predict the occurrence of hot cracks, allowing for real-time quality assessment without the need for post-welding preparation or specialized equipment, using simple measurement systems that can be integrated into the welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (fractured surface samples, scanning electron microscopy, X-ray imaging, or ultrasound examinations) are used to detect hot cracks, then detection accuracy is improved, but detection time and labor intensity increase significantly
Solution Approach 1:
The patent performs preliminary detection of hot cracks during the welding process itself by monitoring radiation from the solidified melt, rather than waiting until after welding is complete. This allows crack detection to occur in advance of traditional post-weld inspection methods, enabling real-time quality assessment and eliminating the need for time-consuming post-weld preparation and analysis
Solution Approach 2:
The patent replaces mechanical and complex imaging systems (scanning electron microscopy, X-ray imaging, ultrasound examinations) with an optical detection system that measures radiation emitted by the solidified melt. This substitution uses electromagnetic radiation detection instead of mechanical sectioning or complex imaging equipment, dramatically reducing detection time and equipment complexity while maintaining detection capability
2Reliability
If post-welding preparation and specialized equipment are used for hot crack detection, then detection reliability is improved, but process complexity and equipment requirements worsen
Solution Approach 1:
The patent utilizes the solidified melt itself as the detection target, which naturally emits radiation that carries information about hot crack formation. The system detects properties inherent to the welding process (radiation from solidifying material) rather than requiring external tracers, special coatings, or complex sample preparation, thereby simplifying the detection system while maintaining reliability
Solution Approach 2:
The patent extracts only the essential detection function from complex post-weld inspection systems by focusing solely on measuring radiation from the solidified melt. This extraction eliminates the need for fractured surface preparation, scanning electron microscopy equipment, X-ray sources, or ultrasound transducers, reducing device complexity to a straightforward optical detection system
3Productivity
If real-time monitoring of molten bath oscillations is implemented, then productivity is improved through faster quality assessment, but measurement system requirements increase
Solution Approach 1:
The patent employs a radiation detection system that serves multiple functions: it monitors the welding process, tracks molten bath oscillations, and detects hot cracks simultaneously. By using the same optical detection infrastructure for multiple purposes, the system achieves real-time quality assessment without requiring separate specialized measurement equipment, thereby maintaining productivity gains while controlling system complexity
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 rapid and efficient quality assessment of weld seams by correlating molten bath oscillations with hot crack formation, reducing the likelihood of hot cracks and optimizing production parameters to minimize their occurrence, thereby improving weld seam quality and reducing production time.
Implementation Method 1
a laser beam (2) is directed onto a workpiece (1)
Implementation Method 2
a so-called molten bath of molten workpiece material is produced on the workpiece around the focal spot of the laser beam
Implementation Method 3
there is detected in a spatially resolved manner radiation emitted by a solidified melt adjacent to a liquid molten bath
Data Source
AI summary
Methods for determining the quality of a weld of a workpiece welded by laser-beam welding, wherein at least a partial region of a molten pool and/or of a surrounding area of the molten pool is observed by means of a measuring system during the laser-beam welding and the quality of the weld of the welded workpiece is determined on the basis of the observation result. At least one characteristic value that correlates with molten pool oscillation of the molten pool is observed during the laser-beam welding and a measure of an amplitude of the molten pool oscillation and/or a measure of a frequency of the molten pool oscillation is determined from the observed time curve of the characteristic value. A probability and/or a frequency for the occurrence of hot cracks at the weld of the workpiece is inferred.