Laser ultrasonic thickness measuring method and laser ultrasonic thickness measuring device capable of being used for field detection

Abstract

The invention discloses a laser ultrasonic thickness measuring method and a laser ultrasonic thickness measuring device capable of being used for field detection. The laser ultrasonic thickness measuring method is characterized in that a laser beam is sent out by a laser to excite an ultrasonic wave on the surface in a specific position of a measured object; meanwhile, an excited wave signal and an echo wave signal produced on the surface in the position are received by an air coupling sensor on the same side of the measured object as the laser; and the propagation distance of the ultrasonic wave is calculated according to the time difference between the excited wave signal and the echo wave signal, and a longitudinal wave propagation velocity of the measured object, so that thickness measurement of the specific position is realized. The device mainly comprises the laser, a main supporting seat, the air coupling sensor, a supporting rod, a centering device, a signal processing system and a display system. The device has a simple and light structure, and can meet the requirements of field detection; and through the adoption of the non-contact type detection method, the thicknesses of high temperature and high-corrosive measured objects can be measured.

Description

technical field [0001] The invention relates to a laser ultrasonic thickness measuring method and device for on-site detection, and the method and device belong to the field of non-destructive testing. technical background [0002] Ordinary ultrasonic thickness gauges need to directly contact the probe on the surface of the measured object with smeared body and couplant for thickness measurement, but the probe used cannot contact the measured object with high temperature or highly corrosive materials. In chemical plants or other enterprises using pressure vessels, containers and some pipelines will generate high heat during operation, which cannot be detected by ordinary contact probes, and the detection of on-site pipelines and equipment arrangements is complicated, due to the narrow space, In the case of a high detection position, the detection staff cannot approach the object to be measured. For the occurrence of the above situation, it is necessary to use non-contact de...

AI Technical Summary

Problems solved by technology

Patent No. CN00809253.2 provides a laser ultrasonic detection method for detecting high-temperature pipelines, using two lasers, one is used to generate ultrasound propagating in the pipe wall at a specific generation point on the surface of the pipe, The other is coupled with an interferometer to detect the ultrasonic echo generated at a detection point on the surface, but this device uses two lasers with high cost and is not suitable for on-site detection. This patent uses lasers and air The combination of coupled sensors reduces the cost, uses the centering device to adapt to different detection environments, increases the flexibility of device detection, and overcomes the above shortcomings

Images