Large Rotary Workpiece Automatic Ultrasonic Testing System Design And Implementation

The large cylindrical parts have abroad applications in many fields such as aviation, spaceflight and power and so on. As an important part to assure the reliability of the equipment, the internal defect inspection for large cylindrical parts has been a hot spot. Currently the main detecting method is manual ultrasonic testing, so the final detection result depends on the experience of staff, the work force is strong, production efficiency and detection quality is poor.In view of above problems, an automated detection system based on digital ultrasonic flaw detector for large cylindrical parts is developed in this paper. The design process of this system comprises of four key steps. Firstly, according to the systems requirements and the workpiece’s features, a4-axis scanning mechanism is designed for the vertical, horizontal and rotary movement of the probe, and also for the rotary motion of work piece. Secondly, the fuzzy PID control algorithm with dead band elimination is proposed to achieve high-precision position control of the probe. The algorithm is simulated in MATLAB/SIMULINK environment and the results demonstrate that the algorithm has higher motion control performance than the traditional algorithm. Then the electrical control circuit and the signal collection circuit are designed, in which the collection circuit takes the STC89C52microcontroller as control center and consists of interface circuit, communication module, power supply module, etc. Finally, the host computer interface and the software for probe’s automatic scanning, characteristic signal acquisition and graphical display are programmed by LabVIEW. Among them, the probe automatic scanning software is composed of parameter configuration module, the fuzzy PID control algorithm with the function of dead band elimination, the water path distance adjustment module, condition monitoring module, etc. The software for characteristic signal acquisition and graphical display also has the function of coordinate transformation, signal extraction and processing.The performances of the automated ultrasonic detection system were tested after the stages of designing and debugging. Experiment results show that the auto-detection requirement of the rotary forgings is satisfied, the problems of manual measurement are solved and the accuracy and efficiency of the internal defect inspection are enhanced greatly.