Welded Portion Inspection Using Laser Switching and Threshold Detection
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Solution Overview
Problem
Existing welded portion inspection methods face challenges in accurately identifying emitted light from molten portions during the transition from welding to inspection, leading to potential interference and reduced reliability in assessing the welded state.
Innovation Solution
The method involves a two-step irradiation process where welding laser light is interrupted to switch to inspection laser light, allowing for the reception of emitted light intensity waveforms, with specific threshold points identified to determine the inspection period, ensuring accurate identification of the inspection start and end times and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If light reception is started before inspection laser light irradiation (during welding laser irradiation), then the transition time from welding to inspection is reduced, but the emitted light from workpieces during welding is received, hindering accurate inspection
Solution Approach 1:
The patent segments the light reception process into distinct phases: a first light reception period during welding laser irradiation, and a second light reception period during inspection laser irradiation. By separating these periods and identifying their boundaries through threshold detection in the intensity waveform, the system can start reception before inspection without mixing the two types of light signals, thus resolving the contradiction between reduced transition time and maintained inspection accuracy.
2Measurement precision
If welding laser light irradiation is interrupted and switched to inspection laser light, then accurate identification of inspection period becomes possible, but the inspection process becomes more complex
Solution Approach 1:
The patent employs self-service by using the intensity waveform itself to automatically identify the boundaries between welding and inspection periods. The system detects threshold values in the waveform to determine when inspection starts and ends, eliminating the need for external timing signals or complex coordination mechanisms. This self-identifying approach maintains high precision while minimizing added complexity.
Solution Approach 2:
The system uses feedback from the detected intensity waveform to control the light reception process. By continuously monitoring the waveform and identifying threshold-based transition points, the system automatically adjusts the reception windows to match the actual welding and inspection periods, ensuring accurate identification without requiring complex pre-programmed timing.
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 high-accuracy inspection of the welded state by accurately identifying the inspection laser light irradiation period, enhancing the reliability of the inspection process even with materials of higher heat conductivity or high-output welding conditions.
Implementation Method 1
a first irradiation step of irradiating the workpieces with welding laser light along a weld trajectory set on the workpieces for welding the workpieces
Implementation Method 2
a light receiving step of receiving emitted light emitted from the workpieces due to the irradiation of the workpieces with the welding laser light and the inspection laser light
Data Source
AI summary
A welded portion inspection method accurately identifies emitted light from a molten portion during inspection laser light irradiation, enabling reliable inspection. When transitioning from welding laser light irradiation to inspection laser light irradiation, the welding laser light irradiation is interrupted and then the welding laser light is switched to the inspection laser light. In inspecting a welded portion, two points in time at which the emitted light intensity is equal to or less than a certain threshold value are extracted from an intensity waveform of the emitted light as an inspection start point in time and an inspection end point in time. The interval between the inspection start and end points is estimated as being a irradiation period of the inspection laser light. The welded state is inspected based on the intensity waveform of the emitted light in the irradiation period.