Measuring and testing – Vibration – By mechanical waves
Patent
1998-11-17
2000-10-31
Williams, Hezron
Measuring and testing
Vibration
By mechanical waves
73644, 73159, G01N 2906, G01N 2926
Patent
active
061385158
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the non-destructive control of moving products, especially a steel strip in the course of its manufacturing process in the iron-and-steel industry.
More specifically, the invention relates to the ultrasonic detection of defects in such a strip by subjecting it to guided vibratory waves, for example so-called Lamb waves.
Lamb waves are ultrasonic vibrations which propagate in the thickness of the product to be inspected, being guided by opposed plane faces of the product. In the case of flat products, such as a metal strip, the waves, channeled by the two parallel plane faces of the product to be inspected, propagate transversely to the direction of movement, and therefore along the width of the strip, from a point of emission, chosen for placing the transducer, to an edge where they are reflected, thereby producing a strong echo signal. Any defect, for example a nonmetallic inclusion, present in the strip or emerging on the surface thereof during passage of the wave represents a local discontinuity of the material transversed which responds with a signal, the intensity of which depends on the size and nature of the defect and the moment of appearance of which, between the emission echo and the edge echo, is representative of the point on the strip where the defect occurs.
The industrial practice is generally to use two transducers, arranged one after the other in the direction of movement of the strip. Each transducer is placed near a different edge of the strip and emits in the direction of the opposite edge. In this way, the strip is scanned twice in a short time interval and in opposite directions, thereby improving the reliability of the results of the analysis, as well as coverage of the area probed.
DESCRIPTION OF THE PRIOR ART
According to a known embodiment to which the invention relates, the transducer is housed inside a hollow wheel made of flexible material, filled with an acoustic coupling fluid (in general, water). This sensor wheel comes into running contact when pressed against the moving strip, thus ensuring that there is, in front of the transducer, a thickness of coupling fluid permanently matched to the distance which separates the transducer from the strip.
In general, provision is made for the bearing force of the wheel to be adjusted in order to allow intimate contact with the strip and thus to reduce the acoustic interface effect. However, an external supply of lost coupling fluid having good wetting properties, for example mineral oil, is always provided between the wheel and the strip in order to ensure perfect coupling at this interface. However, it seems that the known apparatuses of this type are now reaching their limit of use. This is because the results that they give as the speed of movement of the strip exceeds 100 m/min., as is very often the case in modern plants, quickly degenerate, or even become unusable.
SUMMARY OF THE INVENTION
The object of the present invention is to achieve defect detection in products moving at high speed, of the order of 500 or 600 m/min., or even higher.
For this purpose, the subject of the invention is an apparatus for the acoustic detection of defects in a moving product, such as a steel strip during its production, comprising at least one guided-wave (Lamb-wave) ultrasonic transducer housed inside a sensor wheel made of flexible material, which contains an acoustic coupling fluid and is designed to come into running contact with the surface of the product to be inspected, which apparatus is distinguished by the fact that it has, on the one hand, a runner for contact with the surface of said product, placed upstream of the sensor wheel in the direction of movement of the product, and, on the other hand, upstream of said runner, a controlled delivery of lost coupling fluid onto the surface of the moving product.
Advantageously, the runner has a well-ground and nondeformable contact surface in order to be able to bear on the surface of the product to be inspected. Preferably, t
REFERENCES:
patent: 2992553 (1961-07-01), Joy
patent: 3028753 (1962-04-01), Joy
patent: 3616684 (1971-11-01), Nusbickel, Jr.
patent: 3628374 (1971-12-01), Laudien et al.
patent: 4928707 (1990-05-01), Kliesch
patent: 5313837 (1994-05-01), Haynes
patent: 5404755 (1995-04-01), Olson et al.
patent: 5505089 (1996-04-01), Weigel
Moufle Jean-Pierre
Piquemal Philippe
Cole Thomas W.
Miller Rose M.
Sollac
Williams Hezron
LandOfFree
Apparatus for the acoustic detection of defects in a moving stri does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for the acoustic detection of defects in a moving stri, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for the acoustic detection of defects in a moving stri will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2039796