US 12,140,564 B2
Defect detection method, defect detection device, and additive manufacturing device
Misaki Fukuyama, Tokyo (JP); Nobuhiro Higuchi, Tokyo (JP); and Natsuse Morimoto, Tokyo (JP)
Assigned to MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
Appl. No. 17/802,615
Filed by MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
PCT Filed Feb. 16, 2021, PCT No. PCT/JP2021/005711
§ 371(c)(1), (2) Date Aug. 26, 2022,
PCT Pub. No. WO2021/182032, PCT Pub. Date Sep. 16, 2021.
Claims priority of application No. 2020-043735 (JP), filed on Mar. 13, 2020.
Prior Publication US 2023/0135790 A1, May 4, 2023
Int. Cl. G01N 29/04 (2006.01); B22F 10/85 (2021.01); B22F 12/90 (2021.01); B29C 64/268 (2017.01); B29C 64/393 (2017.01); B33Y 40/00 (2020.01); B33Y 50/02 (2015.01); G01N 29/12 (2006.01); G01N 29/24 (2006.01)
CPC G01N 29/043 (2013.01) [B22F 10/85 (2021.01); B22F 12/90 (2021.01); B29C 64/268 (2017.08); B29C 64/393 (2017.08); B33Y 40/00 (2014.12); B33Y 50/02 (2014.12); G01N 29/12 (2013.01); G01N 29/2418 (2013.01); G01N 2291/014 (2013.01); G01N 2291/0289 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A defect detection method, comprising:
a step of irradiating an object with a pulsed laser beam to continuously generate ultrasonic waves in the object;
a step of detecting presence or absence of an internal defect of the object on the basis of presence or absence of resonance of the ultrasonic waves occurring between a surface of the object and the internal defect;
a step of, if the internal defect is detected, identifying a depth position of the internal defect on the basis of a repetition frequency of the pulsed laser beam when the resonance occurs; and further comprising a step of setting the repetition frequency of the pulsed laser beam so as to correspond to a frequency with a half wavelength equal to a depth from the surface of the object to the internal defect to be detected.