Laser Weld Depth Measurement by Keyhole Spot Alignment
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Solution Overview
Problem
Existing methods for optically measuring welding depth in laser welding are inaccurate due to indirect determination of the measuring light beam's position relative to the vapor capillary (keyhole), making precise positioning challenging.
Innovation Solution
A method that couples a measuring light beam into the processing beam path of a laser processing head, focusing it onto the workpiece surface to form a measuring light spot, which is then guided over the vapor capillary to determine its position accurately, allowing precise alignment with the keyhole for reliable welding depth measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect camera-based methods are used to determine measuring beam position, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately determine keyhole position
Solution Approach 1:
The patent introduces a camera as an intermediary device to capture images of the keyhole, which then enables precise determination of the measuring beam position relative to the keyhole. The camera serves as a mediator between the laser processing system and the measurement system, providing visual feedback that allows for accurate positioning without direct mechanical coupling.
Solution Approach 2:
The patent replaces indirect mechanical or geometric positioning methods with optical imaging methods. Instead of using mechanical alignment or geometric calculations to determine beam position, the system uses camera-based optical field analysis to directly visualize and measure the keyhole position, achieving higher precision through optical rather than mechanical means.
2Productivity
If the measuring light beam is not precisely aligned with the vapor capillary, then measurement speed is maintained, but measurement precision deteriorates due to inaccurate welding depth measurement
Solution Approach 1:
The patent implements a feedback mechanism where the camera continuously monitors the keyhole position and provides real-time information about the measuring beam's alignment with the keyhole. This feedback allows for dynamic adjustment of the measuring beam position to ensure it remains precisely aligned with the vapor capillary throughout the welding process, maintaining both speed and accuracy.
Solution Approach 2:
The patent performs preliminary positioning of the measuring beam by using camera images to determine the optimal position before actual welding depth measurement begins. This preliminary alignment ensures that the measuring beam is correctly positioned relative to the keyhole at the start of measurement, preventing positioning errors during the measurement process.
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 precise and reliable measurement of welding depth by directly aligning the measuring light beam with the vapor capillary, improving measurement accuracy and allowing continuous monitoring and readjustment of welding depth during the process.
Implementation Method 1
The measuring light beam is bundled or focused onto the surface of a workpiece by focusing optics of the processing beam path in order to form a measuring light spot there
Implementation Method 2
optical coherence tomograph for determining a surface topography in an impact area of a working laser beam on a workpiece, in particular for determining a keyhole depth
Data Source
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AI summary
The invention relates to a method for measuring the weld penetration depth, particularly during welding, drilling, or ablation using a laser beam (36), in which a measuring light beam (28) from a sensor system (10) is coupled into a processing beam path (30) of the laser beam (36) in a laser processing head (26) and is bundled or focused by a focusing optic (42) of the processing beam path (30) into a measuring light spot on the surface of a workpiece (44). The measuring light beam (28) reflected from the surface of the workpiece is then returned to a measuring and evaluation unit (12) of the sensor system (10) to obtain information about the distance of the surface of the workpiece (44) from the laser processing head (26).To obtain a surface profile of the workpiece in the area of the vapor capillary (54), from which the position of the vapor capillary (54) relative to the point of impact of the working laser beam can be determined, the position of the measuring light spot on the surface of the workpiece (44) is moved both in the welding direction and transversely to it over the vapor capillary (54). The measuring light spot is then moved to the determined position of the vapor capillary (54) to measure the weld penetration depth during laser processing.