Laser Weld Penetration Measurement with Rear-Shifted Beam Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser welding devices face inaccuracies in measuring the penetration depth of welds due to potential misalignment of optical axes caused by beam splitter warping, leading to shallower measurements than the actual deepest portion of the keyhole.
Innovation Solution
The method involves emitting a measurement beam with a different wavelength coaxially aligned with the laser beam, determining the direction of optical axis deviation, and adjusting the irradiation position of the measurement beam to the rear side of the laser beam's optical axis during welding to ensure accurate penetration depth measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the beam splitter is used to align and split the laser beam and measurement beam, then the optical path can be combined in a compact structure, but the beam splitter may warp due to heat causing misalignment of optical axes
Solution Approach 1:
The patent removes the beam splitter from the optical path by using separate optical paths for the laser beam and measurement beam. The laser beam and measurement beam are emitted through different optical systems without requiring a beam splitter, thereby eliminating the warping issue caused by heat accumulation in the beam splitter while maintaining the ability to perform both welding and measurement functions.
Solution Approach 2:
The patent introduces a beam position adjuster as an intermediary component to compensate for optical axis misalignment. This adjuster can shift the position of the measurement beam to correct for any deviation caused by thermal effects, ensuring accurate measurement without requiring the beam splitter to maintain precise alignment under thermal stress.
2Device complexity
If the measurement beam is coaxially aligned with the laser beam, then the measurement system is simplified, but the measurement beam may deviate forward in the welding direction causing shallower depth measurements
Solution Approach 1:
The patent performs preliminary alignment adjustment by positioning the measurement beam irradiation point on the rear side of the laser beam optical axis before welding begins. This preliminary positioning compensates for the expected forward deviation during welding, ensuring that the measurement beam will correctly target the keyhole bottom at the actual penetration depth rather than a shallower position.
Solution Approach 2:
The patent replaces the traditional mechanical alignment approach with an optical compensation method. Instead of physically adjusting the entire optical system to maintain perfect coaxial alignment, the system uses optical path length measurement and beam position calculation to determine and compensate for alignment deviations, achieving accurate measurement without complex mechanical adjustment mechanisms.
3Ease of operation
If the optical axis of the measurement beam deviates forward in the welding direction, then the setup is simpler, but the measured depth will be shallower than the actual deepest portion of the keyhole
Solution Approach 1:
The patent replaces direct mechanical positioning with optical measurement and calculation. The system measures the optical path length of the measurement beam and calculates the actual penetration depth based on this measurement, compensating for any forward deviation of the beam. This allows the system to maintain simple beam positioning while achieving accurate depth measurement through computational correction.
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 reduces variations in measured values and allows for accurate determination of the penetration depth, preventing shallower measurements and ensuring the depth of the keyhole is accurately specified.
Implementation Method 1
The measurement beam is reflected from the bottom of the keyhole and received by an optical interferometer via a beam splitter. Since the optical interferometer can measure the optical path length of the measurement beam, the depth of the keyhole is detected from the measured optical path length
Implementation Method 2
Laser welding devices are known that evaluate the quality of weld portions by directly measuring the depth of penetration of the weld portions
Implementation Method 3
laser welding method for welding a weld portion by using a laser beam
Data Source
AI summary
A plurality of values measured are relatively compared to determine an optical axis deviation direction in which an optical axis of a measurement beam S deviates from a laser beam L. In performing laser welding in the optical axis deviation direction, an irradiation position of the measurement beam S is changed so that the irradiation position of the measurement beam S is moved to a rear side of the center of the optical axis of the laser beam L in the welding direction.