Laser Ultrasonic Weld Inspection Using Reflected Wave Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing welding inspection devices inaccurately determine the presence of internal defects in welds due to variations in ultrasonic signal intensity caused by factors other than the defect, such as surface properties and electrical noise.
Innovation Solution
A welding inspection device that calculates the reflected wave reaching time period and determines the presence of an internal defect by comparing it to a reference time period, using a control device that also considers the degree of attenuation of the reflected wave, and employs a laser interferometer for precise measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the presence or absence of an internal defect is determined based on the degree of attenuation of the intensity of the lower surface reflected wave, then the inspection method is simple, but the determination accuracy is low due to variations in ultrasonic signal intensity caused by factors other than internal defects
Solution Approach 1:
The patent changes the detection parameter from ultrasonic signal intensity to ultrasonic wave reaching time period. By measuring when the reflected wave arrives rather than how strong it is, the system avoids the influence of surface properties and electrical noise that cause intensity variations, thereby improving defect determination accuracy while maintaining inspection simplicity
Solution Approach 2:
The patent introduces an intermediary parameter (reaching time period) that indirectly indicates the presence of internal defects. Instead of directly measuring signal intensity which is affected by multiple factors, the system uses the time period as an intermediary that is less sensitive to external influences, thereby improving measurement precision
2Ease of operation
If the ultrasonic signal intensity is used to determine internal defects, then the measurement process is straightforward, but the reliability is low due to external influences on signal intensity
Solution Approach 1:
The patent changes the measurement parameter from signal intensity to reaching time period. This parameter change maintains operational simplicity while significantly improving reliability because the time period is less affected by external factors such as surface properties and electrical noise that cause intensity variations
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 accurately determines the presence of internal defects by focusing on the delay in the reflected wave reaching time period and its attenuation, reducing errors from external influences on ultrasonic signal intensity.
Implementation Method 1
a transmission laser irradiation device that irradiates a weld with transmission laser light for excitation of ultrasonic waves
Implementation Method 2
a laser interferometer that measures interference of reflected light of the reception laser light
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A welding inspection device (1) includes: a transmission laser light irradiation device (12) that irradiates a transmission point (32) on a weld (6) with transmission laser light (14); a detection device (a reception laser source (16) and a reception laser light probe (18)) that detects an ultrasonic wave generated by the transmission laser light (14) and reaching a reception point (36) on the base material (2, 4); and a control device (22) that determines a presence or absence of an internal defect (40) in the weld (6). The control device (22) extracts, from a result of detection by the detection device (16, 18), a result of detection of a reflected wave that has been reflected by a lower surface (5) of the base material (2, 4) and has reached the reception point (36), calculates a reflected wave reaching time period using the extracted result of detection of the reflected wave, the reflected wave reaching time period being a time period during which the reflected wave travels from the transmission point (32) to the reception point (36), and determines the presence or absence of the internal defect (40) in the weld (6) based on whether or not the calculated reflected wave reaching time period is delayed with respect to a reference time period.