Laser Welding Quality Inspection via Plasma Light Filtering
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Solution Overview
Problem
Conventional laser welding quality inspection methods are inefficient due to the dominance of laser reflected light, requiring complex processes and professional expertise, and struggle to accurately assess welding quality using the variation of the DC component of the plasma signal, especially in vehicle body laser welding where numerous metal combinations exist.
Innovation Solution
A method and apparatus utilizing a single sensor signal and filtered electrical signal of the plasma light, employing frequency division and filtering/amplification to synthesize and output the instantaneous variation of the plasma light, allowing for correct welding quality inspection through a multi-divided composite signal processing scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser reflected light is monitored for welding quality inspection, then the inspection process can be implemented, but the laser reflected light occupies the majority of the signal making it impossible to correctly measure welding quality
Solution Approach 1:
The patent extracts and removes the laser reflected light component from the processed light signal using optical filters. By separating the desired plasma light information from the dominant reflected light background, the system can accurately measure welding quality parameters without interference from the overwhelming reflected light signal.
Solution Approach 2:
The patent introduces optical filters as intermediary components between the light source and detector. These filters act as mediators that selectively transmit plasma light wavelengths while blocking laser reflected light, enabling accurate quality measurement without directly confronting the signal dominance problem.
2Ease of operation
If conventional signal comparison method is used, then the inspection process is simple, but professional technique and extensive data collection are required making it difficult for general workers to set
Solution Approach 1:
The patent enables the inspection system to automatically establish its own operating parameters by utilizing the inherent characteristics of the welding process itself. The system uses the plasma light signal properties that naturally vary with welding quality to automatically set appropriate thresholds and parameters, eliminating the need for external expert configuration.
Solution Approach 2:
The patent changes the inspection approach from comparing against fixed reference waveforms to monitoring dynamic parameter changes in the plasma light signal. By focusing on signal variations and trends rather than absolute values, the system becomes easier to operate while maintaining accuracy across different welding conditions and material combinations.
3Measurement precision
If DC component of plasma signal is used for quality inspection, then the inspection can be performed, but it struggles to accurately assess welding quality especially with numerous metal combinations
Solution Approach 1:
The patent transitions from static DC component analysis to dynamic AC component analysis of the plasma light signal. By monitoring temporal variations and frequency characteristics of the plasma signal rather than steady-state values, the system can accurately assess welding quality across diverse metal combinations without requiring reconfiguration for each material type.
Solution Approach 2:
The patent adds a temporal dimension to the quality inspection by analyzing the AC component and frequency characteristics of the plasma light signal over time. This dimensional transformation from static to dynamic analysis enables the system to distinguish between different welding quality conditions and adapt to various metal combinations through pattern recognition rather than material-specific calibration.
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
Facilitates accurate and efficient laser welding quality inspection, reducing the need for complex processes and professional expertise, enabling the method's application to vehicle body laser welding processes by using the instantaneous variation of the plasma light's AC component.
Implementation Method 1
a quality inspection sensor for sensing a plasma light generated from a laser welding part and for outputting a plasma light sensing signal
Data Source
AI summary
The present invention relates to a method and apparatus for inspecting the quality of laser welding by monitoring the size of a metal molten pool (i.e., weld metal) during a laser welding process. The present invention provides a method and apparatus for inspecting the quality of laser welding, in which a new type laser welding quality inspection system is implemented in which one sensor signal and one filtered electrical signal of the plasma light can be used to perform a correct welding quality inspection through the development of a filtering method of an electrical signal of the plasma light, thereby facilitating a laser welding quality management and making possible its example application to a vehicle body laser welding process.