OCT Weld Bead Control for Consistent Laser Welding of Bar Conductors
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Solution Overview
Problem
Existing laser welding methods for metallic rod conductors in electrodynamic machines face challenges such as surface contamination, roughness, misalignment, and excessive spatter, leading to inconsistent energy input and inadequate bonding areas, requiring time-consuming destructive testing or CT/X-ray evaluation for quality assurance.
Innovation Solution
A method using optical coherence tomography (OCT) for real-time monitoring and control of the laser welding process, adjusting parameters based on actual geometry measurements of the weld pool and bead to ensure a sufficiently large bonding area, and implementing a system that includes a laser scanner to detect and adjust the laser beam, which includes a laser scanner to ensure consistent bonding, and a computer program product to automate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed with constant power and duration, then the welding process is simple and fast, but the bonding area becomes insufficient due to energy input variations from surface contamination, roughness, misalignment, and spatter
Solution Approach 1:
The patent implements real-time feedback control by monitoring the actual geometry of the molten pool and weld bead during laser welding using optical sensors. The system continuously compares measured parameters (molten pool diameter, weld bead height, weld bead diameter) against target values and dynamically adjusts laser power and welding speed to maintain consistent bonding area despite variations in surface conditions, misalignment, or spatter.
Solution Approach 2:
The patent performs preliminary measurement and planning by scanning the workpiece surface and determining optimal welding parameters before the actual welding process. The system calculates the required laser power and speed adjustments in advance based on pre-measured geometric characteristics, enabling proactive compensation for potential defects rather than reactive correction.
2Reliability
If destructive testing or CT/X-ray evaluation is used to verify bonding area, then quality assurance is thorough, but the process becomes time-consuming and requires manual rework of defective parts
Solution Approach 1:
The patent replaces destructive mechanical testing and time-consuming CT/X-ray evaluation with non-contact optical measurement systems. Using optical sensors and image processing, the system measures weld bead geometry in real-time during the welding process, providing immediate quality feedback without physical contact, destruction of the workpiece, or extended inspection time.
Solution Approach 2:
The patent enables continuous quality monitoring throughout the welding process rather than intermittent post-weld inspection. The optical measurement system operates continuously during welding, providing real-time data on molten pool and weld bead geometry, allowing immediate detection and correction of defects while the welding process is still ongoing.
3Device complexity
If visual inspection is performed by operator or random sampling is used, then the process remains simple, but the bonding area verification is insufficient and unreliable
Solution Approach 1:
The patent introduces an intermediary optical measurement system that bridges the gap between simple visual inspection and complex destructive testing. The system uses optical sensors and image processing algorithms to automatically measure weld bead geometry with high precision, providing objective quantitative data rather than subjective visual assessment, while maintaining relative system simplicity through non-contact measurement.
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 fast, non-destructive, and non-destructive quality control of the welding process, ensuring a sufficient bonding area by automatically correcting deviations in real-time, reducing the need for manual rework.
Implementation Method 1
determining an actual geometry of the molten pool and/or the weld bead based on one or more line scans
Implementation Method 2
welding two rod conductors made of metallic material, in particular copper or aluminum, by means of a processing laser beam which is directed at adjacent end faces of the rod conductors in order to melt a molten pool
Data Source
Figure 1~3
AI summary
In a method for monitoring and/or controlling a laser welding process for welding two workpieces (2) made of metal material, more particularly copper or aluminium, preferably two bar conductors, by means of a processing laser beam (3) which is directed to end surfaces (4) of the workpieces (2), said end surfaces being arranged adjacently to one another, in order to melt a molten bath (8) at the two end surfaces (4) and subsequently to melt a melting bead (9) which then solidifies to form a welding bead (9'), the liquid molten bath (8) and/or the liquid melting bead (9) is/are, during the laser welding process, scanned by means of an OCT measurement beam (10) in a line scan (12), an actual geometry of the molten bath (8) and of the melting bead (9) is determined based on the line scan (12), and a welding parameter is set, more particularly controlled, based on a deviation of the determined actual geometry from a predefined target geometry of the molten bath (8) and the melting bead (9). After the laser welding process, the solidified welding bead (9') is scanned by means of an OCT-20 measurement beam (10) in a line scan (10), an actual geometry of the welding bead (9') is determined based on the line scan (12) and the quality of the welding bead (9') is monitored based on a deviation of the determined actual geometry from a predefined target geometry of the welding bead (9').