US 6,474,163 B1 · Ultrasonic flaw detection method and instrument therefor

Abstract

A method and apparatus for ultrasonic flaw detection of line focus type suitable for detection of flaws in nonmetallic materials included in an object. Ultrasonic transmitter and receiver elements of line focus type are opposed at a distance (L) with an object under test placed between them, and a maximum ultrasonic echo is obtained at a distance Lp expressed by: Lp=0.75(FT+FR)−{(CS/CW)−1}t where FT (mm) is the focal length in the medium of the ultrasonic transmitter element of line focus type, FR (mm) is the focal length in the medium of the ultrasonic receiver element line focus type, CS (m/sec) is the speed of ultrasound in an object under test, CW (m/sec) is the speed of ultrasound in the medium, and t (mm) is the thickness of the object under test.

Claims18

Dependent claims

An ultrasonic flaw detection method comprising the steps of:

transmitting ultrasonic waves into a sheet being inspected approximately in a perpendicular direction to the sheet through a coupling medium with a line-focused ultrasonic transmitter;
receiving ultrasonic waves reflected at an internal flaw through the coupling medium with a line-focused ultrasonic receiver;
amplifying the received ultrasonic signals which have been transformed into electrical signals;
picking up amplified signals of the echo from the internal flaw;
and detecting the flaw by detecting a signal more than a predetermined threshold amplitude, wherein the transmitter and the receiver are arranged face to face with the sheet being inspected between them, and wherein a gap length (L) between the transmitter and the receiver is near a minimum value (Lp) in which the height (f(L))of the echo from the internal flaw takes a maximum value.

2 more elements

Dependencies are inferred from the claim text.

Ultrasonic flaw detection method and instrument therefor

Life of this patent

Ultrasonic flaw detection method and instrument therefor

Life of this patent

Abstract

Claims18