Laser Welding Head With Orbital Light for Penetration Depth Accuracy
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Solution Overview
Problem
Existing laser welding devices face challenges in accurately measuring weld penetration depth due to optical axis misalignment between laser light and measurement light, which can result in shallower measurements than the actual deepest part of the keyhole.
Innovation Solution
A laser welding device that moves the irradiation position of the measurement light along a predetermined welding path, with its optical axis positioned within a radius smaller than half of the laser light's spot diameter, allowing for repeated measurements within a fixed time period to determine the weld penetration depth accurately, even with misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the measurement light and laser light are coaxially overlapped to measure weld penetration depth, then the measurement can be performed simultaneously with welding, but optical axis misalignment occurs due to vibrations causing inaccurate measurements
Solution Approach 1:
The patent introduces orbital movement of the measurement light around the laser light axis, transitioning from a single-point coaxial measurement to a multi-point circumferential measurement. This dimensional change allows the system to capture depth information from multiple angles, compensating for optical axis misalignment and identifying the true maximum penetration depth even when vibrations occur during welding.
Solution Approach 2:
The system performs preliminary orbital scanning of the measurement light around the keyhole before final depth determination. This preliminary action collects multiple measurement data points that are used to identify the maximum penetration depth, ensuring accurate measurement even if the optical axis shifts during the welding process.
2Ease of operation
If the optical axis of measurement light is misaligned frontward in the welding direction, then the measurement light applies to a curved portion with shallower penetration, but the measured depth becomes shallower than the actual deepest part
Solution Approach 1:
By moving the measurement light in an orbital path around the laser axis rather than maintaining a fixed coaxial position, the system samples multiple locations including the deepest part of the keyhole. This multi-dimensional approach ensures that even with frontward misalignment, the measurement light will eventually intersect the true maximum penetration depth location during its orbital motion.
Solution Approach 2:
The system continuously monitors multiple measurement values obtained during orbital movement and uses feedback to identify the maximum depth value. This feedback mechanism allows the system to distinguish the true penetration depth from shallower measurements taken at misaligned positions, correcting for optical axis misalignment errors.
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 ensures more accurate measurement of weld penetration depth by ensuring the measurement light is applied to the deepest part of the keyhole, reducing errors caused by optical axis misalignment and fluctuating measurements.
Implementation Method 1
the measurement light reflected on the bottom of the keyhole is caused to enter an optical interferometer via a beam splitter. Because the optical interferometer can measure the optical path length of the measurement light
Data Source
AI summary
A laser welding device (10) for welding a weld part (35) with laser light (L) includes: a laser emitting head (20) overlapping the laser light (L) and a measurement light (S) coaxially with each other and applying the laser light (L) and the measurement light (S) to the weld part (35), the measurement light (S) having a wavelength different from a wavelength of the laser light (L); a first parallel plane plate and a second parallel plane plate, changing an irradiation position of the measurement light (S) such that the irradiation position orbitally move around a center of rotation that moves on a predetermined welding path in a radius of rotation that is smaller than ½ of a spot diameter of the laser light (L); a measuring instrument (14) repeatedly measuring a weld penetration depth of the weld part (35) based on the measurement light (S) that is emitted from the laser emitting head (20) and is reflected on the weld part (35) while the measurement light (S) is being orbitally moved; and a determiner (17) determining the weld penetration depth of the weld part (35) using a plurality of measured values of the weld penetration depth, the plurality of measured values being measured by the measuring instrument (14) within a fixed time period while shifting a start time point of the fixed time period.