Trw Limited

John Touhalisky

Thomas Derkacs

Istvan M Matay

Stephan D Murphy

An array of ultrasonic transducer (A) are disposed along a circular arc for examining tubular objects moving therethrough. A calibrating apparatus (B) includes a calibrating cylinder (22) having a plurality of calibrating flaws (24, 26) therein. A rotary positioning device (30) and an axial positioning device (40) adjust the relative spatial relationship of each calibration flaw and transducer. An ultrasonic control instrument (50) produces an echo signal having components corresponding to echoes received from the examined object. A computer (60) includes a gate adjustment control subroutine (66) which selectively separates a preselected component from the echo signal. A pulse amplitude measurement subroutine (64) measures the amplitude of the preselected echo signal component and, first, determines the peak amplitude of the component and, second, compares the amplitude of the component with a preselected standard. A position control subroutine (68), first, serially brings each calibration flaw generally into a preselected spatial relationship with each transducer and, second, adjusts the flaw/transducer spatial relationship until the pulse amplitude measurement subroutine detects the peak amplitude of the selected component. The spatial position of the peak amplitude is recorded in memory as an indication of the actual transducer location. A calibration subroutine (62) adjusts the gain and distance amplitude control adjustments of the ultrasonic instrument until the pulse amplitude measurement subroutine determines that the selected component matches the preselected standard.

Reference standard for calibration of ultrasonic arrays

A first array (A) of ultrasonic transducers transmits ultrasonic shear waves circumferentially around an examined cylindrical object (110). A second array (B) transmits ultrasonic shear waves axially along the examined object. Triggering pulses from a triggering amplifier (22) are switched by a multiplexer (24) to each individual transducer of the first and second arrays. As one of the transducers assumes the role of a transmitting transducer and transmits an ultrasonic wave, the other transducers of the first and second arrays assume a receiving mode to receive reflected ultrasonic components. A wave travel timer (26) measures the duration for an ultrasonic wave to be transmitted from the transmitting transducer to a defect and for a reflected component to propagate from the defect to the receiving transducer. A microprocessor (20) tri-angulates or otherwise computes the location and orientation of a reflective defect from the measured travel time, the spatial relationship of the transmitting and receiving transducers, and the direction of propagation of the transmitted ultrasonic wave.

Growing community of inventors

Eastlake, OH, United States of America

John Touhalisky