APPLICATION OF TRANSDUCER ARRAYS TO ROTARY ULTRASONIC TESTERS

摘要

An automated ultrasonic inspection system must provide high sensitivity for the detection of small defects in all areas of the inspected profile. Other requirements are high repeatability, the absence of false alarms and high throughput rate. Rotary testers are widely used in tube inspection. Meeting all the above requirements occasionally becomes difficult, since improving one aspect may cause the degradation of another. For instance, to improve sensitivity to small defects a shorter beam length has to be selected. This leads to reduced throughput rate. Adding more transducers to the rotary tester can solve the problem. This requires the use of additional inspection channels, which does not represent a technical problem. The problem arises with the need for additional rotary capacitors to connect the inspection instruments to the transducers. Rotary capacitors are precision mechanical components. The number of individual capacitors in a capacitor bank is strictly limited. This paper describes the use of transducer arrays in rotary testers. It is shown that the throughput rate can be increased without additional inspection channels and coupling capacitors. Experimental data are presented to support the related theoretical discussions.