Laser Ultrasonic Weld Inspection Using Reflected Wave Delay
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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 internal defects by comparing it to a reference time period, using a control device to assess delays and attenuation of the reflected wave, thereby improving accuracy beyond reliance on intensity attenuation alone.
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 deteriorates due to variations in ultrasonic signal intensity caused by factors other than internal defects
Solution Approach 1:
The invention changes the detection parameter from ultrasonic signal intensity to ultrasonic wave reaching time period. By measuring when the reflected wave arrives at the reception point rather than how strong it is, the system avoids the influence of intensity variations caused by surface properties and electrical noise, thereby improving determination accuracy without significantly increasing system complexity
Solution Approach 2:
The invention introduces an intermediary parameter (reflected wave 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 wave travel time as an intermediary measurement that is less susceptible to external influences, thus resolving the contradiction between simple inspection and accurate determination
2Ease of operation
If the presence or absence of an internal defect is determined based on ultrasonic signal intensity, then the inspection process is straightforward, but measurement precision deteriorates due to external influences on signal intensity
Solution Approach 1:
The invention changes the measurement parameter from signal intensity to wave reaching time period. This parameter change maintains operational simplicity while eliminating the sensitivity to external influences such as surface properties and electrical noise that plague intensity-based measurements, thereby improving detection 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 method allows for accurate detection of internal defects by focusing on the delay and attenuation of the reflected wave, reducing errors from external influences on ultrasonic signal intensity, ensuring reliable weld inspection.
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
AI summary
A welding inspection device includes: a transmission laser light irradiation device that irradiates a transmission point on a weld with transmission laser light; a detection device (a reception laser source and a reception laser light probe) that detects an ultrasonic wave generated by the transmission laser light and reaching a reception point on the base material; and a control device that determines a presence or absence of an internal defect in the weld. The control device extracts, from a result of detection by the detection device, a result of detection of a reflected wave that has been reflected by a lower surface of the base material and has reached the reception point, 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 to the reception point, and determines the presence or absence of the internal defect in the weld based on whether or not the calculated reflected wave reaching time period is delayed with respect to a reference time period.