Laser Weld Seam Monitoring With Dual Light-Section Detection
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Solution Overview
Problem
Existing methods for monitoring joining seams during laser welding lack accuracy in determining the exact position and geometry of the weld bead, leading to incorrect seam width calculations and difficulty in detecting small defects, as they rely solely on light-section methods that are insufficient for precise lateral detection.
Innovation Solution
A method and device that project light-section lines both before and after the processing point to determine the joint line's position and geometry, allowing for accurate lateral detection of the joining seam's position and geometry, using a camera to record images of these lines and process them to assess the seam's geometry, including width, height, and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If light-section methods are used to monitor joining seams, then the monitoring process can be performed during welding, but the accuracy in determining the exact position and geometry of the weld bead deteriorates
Solution Approach 1:
The monitoring system is divided into two separate light-section devices: one positioned before the processing point to capture joint line position, and another after the processing point to capture weld bead geometry. This segmentation allows each device to specialize in specific measurement aspects, resolving the contradiction between real-time monitoring and measurement accuracy.
Solution Approach 2:
The patent introduces a temporal dimension to the measurement process by capturing images at different positions (before and after processing) and combining them. This multi-dimensional approach enables accurate reconstruction of weld bead geometry while maintaining real-time monitoring capability.
2Device complexity
If single light-section methods are used, then the device complexity is reduced, but the ability to detect small defects and determine seam width deteriorates
Solution Approach 1:
The system uses two specialized light-section devices positioned at different locations (before and after processing point) to capture different aspects of the welding process. This segmentation enables precise defect detection while keeping each individual device relatively simple.
Solution Approach 2:
The patent merges the information from two separate light-section measurements with different functions (joint line positioning and weld bead geometry) to achieve comprehensive defect detection capability that neither device could provide alone.
3Device complexity
If light-section lines are projected only after the processing point, then the system simplicity is maintained, but the accuracy in determining lateral position of the joining seam deteriorates
Solution Approach 1:
The first light-section device projects a light line before the processing point to preliminarily determine the joint line position. This preliminary measurement provides reference information that improves the accuracy of lateral position determination when combined with the post-processing measurement.
Solution Approach 2:
The pre-processing light-section measurement acts as an intermediary that provides reference joint line position data, which mediates between the simple post-processing measurement and the final accurate lateral position determination of the weld bead.
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 of the weld bead's geometry even in complex geometries, ensuring accurate quality assessment by precisely determining the seam's position and geometry, enhancing the detection of small defects and improving overall welding quality monitoring.
Implementation Method 1
a first light-section device (21) for generating a light-section line (25) which lies transversely across a joint line (30) in the processing direction before a processing point, a second light-section device (22) for generating a light-section line (26) which lies transversely across a joining seam (35) behind a processing point
Data Source
AI summary
A method for monitoring a joining seam, in particular during joining by a laser beam, wherein in the processing direction before a processing point a joining site is measured in order to detect the position and geometry thereof, at least one position of a joining seam is determined from the position of the joining point, and in the processing direction after the processing point the joining seam is measured in order to detect the geometry thereof at the determined position. A device is also provided for carrying out said method and to a laser processing head equipped with such a device.