Laser Weld Monitoring Using OCT Reference Element Detection
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Solution Overview
Problem
Current methods for monitoring laser welding processes lack reliability in detecting through welds with open vapor capillaries, which are crucial for assessing the fluid-tightness of weld seams, especially in the production of fuel cells.
Innovation Solution
The method involves directing a measuring beam from an optical coherence tomograph onto the interaction area during laser welding, where it penetrates the workpieces and a reference element, allowing for the acquisition and evaluation of measured values to determine the ratio and variance of values within specific ranges, thereby assessing the presence and density of through welds with open vapor capillaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical coherence tomography is used to evaluate height information in keyhole and surrounding area, then measurement capability is improved, but reliability in detecting through welds with open vapor capillaries deteriorates
Solution Approach 1:
A reference element is introduced as an intermediary object with known, stable optical properties. This reference element serves as a mediator between the measuring beam and the workpieces, providing a consistent reference signal that enables reliable detection of through welds by comparing measured values against the known reference characteristics
Solution Approach 2:
The invention changes the measurement approach by evaluating not only height information but also optical properties such as reflectivity and absorption characteristics. By analyzing multiple parameters including the ratio of measured values within defined ranges and variance of these values, the system achieves reliable through weld detection that overcomes the limitations of height information alone
2Difficulty of detecting and measuring
If measuring beam penetrates workpieces to detect through welds, then detection capability is improved, but measurement complexity increases
Solution Approach 1:
The reference element is positioned and configured in advance with known optical characteristics. By preparing the reference element beforehand with predetermined properties, the system simplifies the measurement process during actual welding detection, as the reference values are already established and do not require complex real-time calculations
Solution Approach 2:
The system uses the reference element to establish feedback mechanisms where measured values are continuously compared against known reference values. This feedback approach simplifies detection by providing a clear comparison基准, enabling the system to reliably identify through welds through ratio and variance calculations rather than complex absolute measurements
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 approach enables reliable detection and assessment of through welds and their fluid-tightness, ensuring higher quality weld seams by monitoring the spatial density and opening status of vapor capillaries in real-time, thus improving the production of fuel cells and other applications.
Implementation Method 1
directing a measuring beam of an optical coherence tomograph onto the interaction area
Implementation Method 2
The measuring beam at least partially penetrates the workpieces in the interaction area in a through weld of the workpieces
Data Source
AI summary
A method for monitoring a laser welding process for welding workpieces by a welding laser beam is provided. The method includes, during the laser welding process, directing a measuring beam of an optical coherence tomograph onto an interaction area in which the welding laser beam interacts with the workpieces. The measuring beam penetrates the workpieces in the interaction area in a through weld of the workpieces. The measuring beam penetrating the workpieces is incident on a reference element. The method further includes acquiring measured values using the measuring beam, defining a first measured value range corresponding to detection of a material of the workpieces, defining a second measured value range corresponding to detection of the reference element, and determine a ratio of a number of measured values lying in the first measured value range and a number of measured values lying in the second measured value range.