Laser Weld Inspection After Surface Impurity Removal
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Solution Overview
Problem
The existing welding inspection methods, such as those disclosed in Japanese Patent No. 5651533, face challenges in accurately detecting internal defects in welds when impurities like slag are present on the surface, as they interfere with the generation of ultrasound and lead to defective inspections.
Innovation Solution
A welding inspection method that involves removing impurities from the weld surface before irradiation with transmission laser light, followed by detecting ultrasound reflections to determine the presence of internal defects, ensuring accurate detection even with surface impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission laser light is irradiated directly on the weld surface for ultrasound generation, then the inspection process is simple and fast, but impurities on the surface interfere with ultrasound generation and cause defective inspection
Solution Approach 1:
The patent applies preliminary action by removing impurities from the weld surface before irradiating with transmission laser light for ultrasound generation. The method includes: (1) irradiating the weld surface with a first laser beam to remove impurities, (2) irradiating the cleaned surface with a second laser beam to generate ultrasound, and (3) detecting the ultrasound to identify internal defects. This preliminary cleaning step ensures that the subsequent ultrasound generation and detection are not interfered with by surface impurities, thereby resolving the contradiction between inspection speed and detection accuracy.
2Measurement precision
If impurity removal step is added before laser irradiation, then detection accuracy is improved, but the inspection process becomes more complex and time-consuming
Solution Approach 1:
The patent merges the impurity removal function and the ultrasound generation function into a single integrated inspection process. By using laser beams that serve dual purposes (cleaning and ultrasound generation) and by integrating the control of multiple laser beams and detection systems into one coordinated process, the patent reduces the overall complexity despite adding the impurity removal step. The merged approach allows sequential execution of cleaning and inspection without requiring separate standalone systems, thus improving detection accuracy while minimizing the increase in process complexity.
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 method allows for appropriate detection of internal defects in welds by removing impurities before the inspection process, ensuring reliable results even when impurities are attached to the surface, thereby enhancing the accuracy of the welding inspection.
Implementation Method 1
irradiating the surface of the weld from which the impurity has been removed with transmission laser light for excitation of ultrasound in inside of a detection target
Implementation Method 2
irradiating a predetermined position on the detection target where reflected ultrasound reflected by a lower surface of a base material of the detection target can be detected, with reception laser light for detection of reflected ultrasound
Data Source
AI summary
A welding inspection method includes a step S102 of removing an impurity at a surface of a weld with a surface treatment apparatus, a step S110 of irradiating the surface of the weld from which the impurity has been removed with transmission laser light, a step S120 of detecting reflected ultrasound reflected by a lower surface of a base material, and a step S150 of determining whether or not there is an internal defect in the weld based on a result of detection of reflected ultrasound.