Self-calibration system for ultrasonic inspection apparatus
First Claim
1. A method of acoustically inspecting a workpiece comprising:
- (a) determining a preselected physical calibration distance along a workpiece being inspected;
(b) measuring a first travel time in which a first acoustic wave travels said calibration distance, said calibration distance being determined acoustically by measuring the travel times of acoustic waves through an acoustic coupling medium that contacts the workpiece along the calibration distance;
(c) adjusting the determined distance for variations in the temperature and pressure of the coupling medium;
(d) determining a calibration acoustic velocity from the calibration distance and the first travel time;
(e) measuring a second workpiece travel time in which a second acoustic wave travels through a portion of the workpiece to be inspected; and
,(f) determining an inspection distance through the workpiece traveled by the second acoustic wave from the calibration acoustic velocity and the second travel time.
1 Assignment
0 Petitions
Accused Products
Abstract
A tubular workpiece (10) undergoes axial and rotational movement relative to a collar (12) filled with an acoustically coupling medium (14). Longitudinal waves are emitted into the coupling medium and the workpiece from a first transducer (22) and acoustic echoes are received thereby. From the coupling medium travel times between the transducer and the surface of the workpiece, a contour reconstruction apparatus (58) reconstructs the peripheral contour of the workpiece. The workpiece travel times are stored in a memory (92) until the longitudinal velocity of the acoustic wave in the workpiece is determined. Transducers (24, 26) emit and detect a Rayleigh wave which travels around the workpiece circumference. A divider (80) divides the workpiece circumference as determined by the contour reconstruction apparatus by the Rayleigh wave travel time to determine the Rayleigh wave acoustic velocity. A multiplier (82) multiplies the Rayleigh wave velocity by a preselected Rayleigh wave to longitudinal wave ratio to determine the velocity of the longitudinal wave in the workpiece. A second multiplier (100) multiplies the stored longitudinal wave travel times by the longitudinal wave velocity to determine the thickness of the workpiece and the depth of any acoustically reflective flaws.
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Citations
19 Claims
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1. A method of acoustically inspecting a workpiece comprising:
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(a) determining a preselected physical calibration distance along a workpiece being inspected; (b) measuring a first travel time in which a first acoustic wave travels said calibration distance, said calibration distance being determined acoustically by measuring the travel times of acoustic waves through an acoustic coupling medium that contacts the workpiece along the calibration distance; (c) adjusting the determined distance for variations in the temperature and pressure of the coupling medium; (d) determining a calibration acoustic velocity from the calibration distance and the first travel time; (e) measuring a second workpiece travel time in which a second acoustic wave travels through a portion of the workpiece to be inspected; and
,(f) determining an inspection distance through the workpiece traveled by the second acoustic wave from the calibration acoustic velocity and the second travel time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An acoustic workpiece inspection system comprising:
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a calibration distance determining means for determining a preselected physical calibration distance along a workpiece being inspected; a first travel time measuring means for measuring a first travel time in which a first acoustic wave travels said calibration distance; calibration acoustic velocity determining means for determining a calibration acoustic velocity from the calibration distance and the first travel time, the calibration acoustic velocity determining means being operatively connected with the calibration distance determining means and the first travel time measuring means; a second travel time measuring means for measuring a second travel time in which a second acoustic wave travels through a portion of the workpiece to be inspected; and
,inspection distance determining means for determining from the second travel time and the calibration acoustic velocity an inspection distance through the workpiece traveled by the second acoustic wave, the inspection distance determining means being operatively connected with the calibration acoustic velocity determining means and the second travel time measuring means. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An acoustic inspection apparatus for inspecting tubular workpieces in which velocities of ultrasonic inspection waves are unknown, the inspection apparatus comprising:
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supporting means for supporting a tubular workpiece to be inspected; an acoustic coupling medium operatively connected with the supporting means to be supported in contact with a first surface of the inspected workpiece, the acoustic coupling medium transmitting longitudinal ultrasonic waves with a predetermined coupling medium velocity; at least one ultrasonic longitudinal wave transducer means for producing ultrasonic longitudinal waves and receiving ultrasonic longitudinal wave echoes, the transducer means being operatively connected with the supporting means in contact with the acoustic coupling medium and oriented to direct ultrasonic longitudinal waves radially toward the workpiece; rotation means for causing relative rotational movement between the workpiece and the transducer means about a central axis of the workpiece, the rotation means producing a rotational position signal indicative of the relative angular orientation of the longitudinal wave transducer means and the workpiece; a coupling medium travel time measuring means for measuring travel time of the ultrasonic longitudinal waves traveling between the transducer means and the workpiece first surface at a plurality of relative angular orientations between the workpiece and the longitudinal wave transducer means; contour determining means for determining a contour of the workpiece first surface, the contour means being operatively connected with the rotation means to receive the rotational position signal therefrom and with the coupling medium travel time measuring means for receiving the measured coupling medium travel times therefrom; calibration distance calculating means for calculating a calibration distance along the workpiece first surface from the contour, the calibration distance calculating means being operatively connected with the contour determining means; at least one surface wave transducer means for producing ultrasonic Rayleigh waves traveling circumferentially along the workpiece first surface over the calibration distance, the surface wave transducer means being operatively connected with the supporting means in cotact with the acoustic coupling medium; a surface wave travel time measuring means for measuring a surface wave travel time in which the Rayleigh wave traverses the calibration distance; an acoustic velocity determining means for determining a longitudinal wave acoustic velocity in the workpiece, the acoustic velocity means being operatively connected with the calibration distance calculating means and the surface wave travel time measuring means; a workpiece travel time measuring means for measuring workpiece travel times in which the longitudinal waves travel between the workpiece first surface and at least one workpiece interface such as an inner workpiece surface and a flaw, the workpiece travel time measuring means being operatively connected with the longitudinal wave transducer means; and
,inspection distance determining means for determining a distance between the workpiece first surface and each interface, the inspection distance determining means being operatively connected with the acoustic velocity determining means and the workpiece travel time means.
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Specification