White Aug. 16, 1983

Ultrasonic thickness measuring apparatus and method
Inventors: White; Dennis A. (Stafford Springs, CT).
Assignee: Hartford Steam Boiler Inspection and Insurance Company (Hartford, CT).
Appl. No.: 333,923
Filed: Dec. 23, 1981
Intl. Cl. : G01N 29/00
Current U.S. Cl.: 73/597; 73/627; 73/628; 73/644
Field of Search: 73/597, 627, 644, 628

References Cited | [Referenced By]

U.S. Patent Documents
2,439,130Apr., 1948Firestone
2,723,556Nov., 1955Willard
3,003,351Oct., 1961Ziegler
3,108,469Oct., 1963Dyer et al.
3,315,520Apr., 1967Carnevale et al.
3,325,781Jun., 1967Harris
3,416,365Dec., 1968Frederick
3,512,400May, 1970Lynnworth
3,554,013Jan., 1971Berg
3,624,712Nov., 1971Weighart
3,720,098Mar., 1973Dixon 73/597
3,844,163Oct., 1974Di Leo
3,918,296Nov., 1975Kitada
3,994,154Nov., 1976Niklas et al. 73/597
4,080,836Mar., 1978Thompson et al. 73/597
4,114,455Sept., 1978Walker 73/629
4,137,779Feb., 1979Wustenberg et al. 73/627
4,182,155Jan., 1980Fowler 73/644
4,338,820Jul., 1982Jassly et al. 73/597
4,375,167Mar., 1983Nusbickel, Jr. et al. 73/644

Other References

D. M. Egle and D. E. Bray, Application of the Acousto-elastic Effect of Rail Stress Measurement, Mar. 1979.


Primary Examiner: Birmiel; Howard A.

Abstract

In a method for ultrasonically measuring the thickness between opposed surfaces of a workpiece from one surface, a velocity parameter of ultrasonic longitudinal waves through the material of a workpiece is measured at a location along a first surface of the workpiece. Ultrasonic longitudinal waves are transmitted from one surface to the opposite surface, and the ultrasonic waves reflected from the opposite surface are received and a time parameter between transmission of the longitudinal waves and reception of the reflected waves is measured. The thickness between the opposed surfaces is determined from the measured velocity parameter and the measured time parameter. A device for measuring the thickness of a workpiece from one surface includes a transducer assembly with a pair of spaced apart transducer units each having a coupling member and a piezoelectric element mounted thereon. A third coupling member has a pair of piezoelectrics elements mounted thereon, and an electrical circuit connected to the piezoelectric elements for control and measurement. The piezoelectric element is mounted on the first coupling member of one of the pair of transducer units at a predetermined angle relative to the bottom surface to generate a subsurface longitudinal ultrasonic wave through the workpiece to be tested and to be received by the other piezoelectric element of the pair of units. The measuring device further includes apparatus for supplying couplant medium to the interface between the bottom surface of the coupling members and on the workpiece, and means for supporting and moving the transducer assembly along the workpiece.

35 Claims, 6 Drawing Figures

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