Laser Welding Quality Evaluation Using Reflected Light
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Solution Overview
Problem
Conventional laser processing devices face challenges in accurately evaluating welding quality due to the need to match the sensor visual field and laser focusing diameter, which can be difficult to maintain, especially when using thermal radiation light for measurement.
Innovation Solution
A laser processing device that includes an oscillator, a mirror, an absorption unit, and a sensor unit, where the absorption unit absorbs a portion of the laser light until a predetermined amount is reached, allowing for evaluation of laser processing quality based on reflected light intensity without requiring precise matching of sensor visual field and laser focusing diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal radiation light measurement is used to evaluate welding quality, then welding quality evaluation is enabled, but accurate measurement requires precise matching of sensor visual field and laser focusing diameter which is difficult to maintain
Solution Approach 1:
The patent extracts and eliminates the problematic requirement of matching sensor visual field with laser focusing diameter by switching from thermal radiation light measurement to reflected light measurement. The sensor now measures reflected light from the workpiece surface rather than thermal radiation, which removes the constraint of needing precise spatial alignment between sensor and laser focus, thereby simplifying the system while maintaining evaluation capability
Solution Approach 2:
The patent changes the measurement parameter from thermal radiation light intensity to reflected light intensity. This parameter change fundamentally alters the measurement approach, allowing quality evaluation based on surface reflectivity characteristics rather than thermal emission, which eliminates the need for precise geometric matching between sensor field and laser focus
2Area of stationary object
If sensor visual field is larger than laser irradiation range, then measurement coverage is increased, but thermal radiation light from outside irradiation range is also measured reducing evaluation accuracy
Solution Approach 1:
The patent converts the previously harmful effect of measuring thermal radiation from areas outside the laser irradiation range into a beneficial measurement of reflected light from the entire sensor field. By measuring reflected light instead of thermal radiation, the larger sensor visual field coverage becomes advantageous as it captures reflected light signals from a broader area, improving signal strength without compromising measurement accuracy
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 configuration enables easy maintenance of evaluation accuracy and direct expression of the processing target's surface shape, improving the accuracy of welding quality assessment by measuring reflected light intensity independently of sensor visual field and focusing diameter alignment.
Implementation Method 1
an absorption unit that receives the first laser light and absorbs the first laser light until an amount of the first laser light becomes equal to or less than a predetermined light amount
Implementation Method 2
first reflected light that is a part of reflected light in which the second laser light with which the processing target portion is irradiated is reflected by the processing target portion is transmitted through the mirror
Implementation Method 3
a mirror disposed in an optical path of the laser light, in which second laser light that is another part of the laser light is reflected by the mirror
Data Source
AI summary
A laser processing device includes: an oscillator that oscillates laser light; a mirror in which second laser light that is another part of laser light is reflected while first laser light that is a part of laser light is transmitted through the mirror to irradiate a processing target portion with second laser light, and first reflected light that is a part of reflected light in which second laser light is reflected by the processing target portion is transmitted through the mirror; an absorption unit that receives and absorbs the first laser light until an amount of the first laser light becomes equal to or less than a predetermined light amount; a sensor unit that measures intensity of the first reflected light; and a quality evaluation unit that outputs an evaluation result representing the quality of the laser processing at the processing target portion based on a measurement result.