Research On Ultrasonic Testing Robot For Pipeline Girth Welds

It's very important to control quality of pipeline girth welds in building and using transportation pipeline. As a main method of NDT (Non-destructive Testing),UT (Ultrasonic Testing) has been widely used to control the quality of product in industry and to inspect the equipment on service, especially has the important function in inspecting pipelines girth welds, and is adopted by many countries. The traditional UT system has some disadvantages, such as low inspective efficiency, difficulty to evaluate defects and so on. So it has great significance to design and develop an automatic UT testing robot for pipeline girth welds.In virtue of the technologies such as computer, NC, precise machinery and micro-motor drive and so on, taking PC as the core of system, taking an advanced digital ultrasonic flaw detector as base, taking virtual instrumentation structure as software platform, a robot system of automatic UT testing for pipeline girth welds has been developed. The digital, automation and picturization of ultrasonic testing are realized, and the foundation for improving the reliability and efficiency of UT is established.The collectivity design of robot is completed. The probe clip is developed, which has realized adaptive contact between probe and pipeline. The step-motor transmission system which has great deceleration ratio is developed, which has satisfied the required power of robot when it makes circle motion along pipeline. Using computer I/O interface and serial communication technologies, through the RS232 serial communication function in LabWindows/CVI, communications between industrial computer and STC89C51 SCM is achieved, so that effectively controlling the robot. The circle motion and axes direction motion along pipeline are realized, so, probe scanning way of hackle or rectangle for welding line has achievedUsing ActiveX technology, interface between the LabWindows / CVI and Office Word software is solved, and the test report can be generated and printed. The platform of bevel ultrasonic testing for the pipeline weld is established. Through researching on the key technology and software realized method of automation scanning imaging, to display the ultrasonic A-scan, B-scan of the typical defects of the pipeline by pseudo-color and gray-scale model is successfully achieved. Through filtering denoising for ultrasonic flaw detection signal, electromagnetic interference and impact of point noise are inhibited effectively. The bevel testing mathematical model of the manual flaw is established, and orientation analyse for the flaw is achieved. All of these have established the foundation for studying further the digital, picturization, and intelligentized of transverse wave testing.