Research on the Ultrasonic Phased Array Detection Method for Thread Defects of Drill Pipe Female Joints

Aiming at the complex thread structure of drill pipe female joints and the great difficulty in detection, this paper proposes a drill pipe thread defect detection method based on ultrasonic phased arrays. By establishing the sound beam propagation model at the flat interface between the wedge and the workpiece, the focusing delay rule of the ultrasonic phased array transducer in axial arrangement was studied. The influences of element number, central frequency, and element spacing on the sound field focusing performance were analyzed to optimize the transducer parameters. Finite element simulation was used to study the effects of different deflection angles, crack depths, and widths on defect echo signals. Results show that when the sound beam deflection angle is 0 degrees, cracks can be quantitatively measured with high precision by the time difference between the crack tip diffraction echo and the thread root echo. When it is 60 degrees, the existence of defects can be judged by the abnormal amplitude of the thread side echo. Field tests indicate that the designed ultrasonic phased array detection system can effectively identify drill pipe thread crack defects, and the simulation results are basically consistent with the experimental ones.