Design Of The Ultrasonic Automatic Testing System For Defects In Drill Collar

Drill collar is the main component of the bottom substructure of drill string. Its quality will have a direct impact on the success or failure of oil drilling. According to great majority of manufacturer's existing production technology, cracked, loosen, folded, layered, pored defects may be included in drill collar. So the ultrasonic automatic testing system designed in the paper has the very important meaning to evaluate its internal quality and guarantee its security and reliability in the process of manufacture and usage.In the paper, the ultrasonic testing theory has been studied and the schema of ultrasonic automatic testing scheme for drill collar has been designed. A testing method of multi-probes synthetic judgment is put forward to test defects in large diameter thick-walled pipe in the paper, which has better popularity and higher sensitivity at internal defect detection of drill collar. The circuits of ultrasonic signal emitting, receiving, magnifying and door selecting control have been designed. Four-channel ultrasonic data acquisition card based on CPLD EPM9560 has been designed, which can collect up to four-channel data circularly and save amplitude, location (the distance from originating wave to defective wave) data of the defects in FIFO to be read by computer. In the meantime, the card can control the selecting and magnifying module of ultrasonic receiving circuit through 82C54 and D/A chips to realize digitization of whole system. The WinDriver is used to develop the card driver. Visual C++ is used to develop control software and comprehensive defection assessment platform of drill collar. It is achieved to set the system parameter, identify the location and type of defection, store and playback the defection data, display the defection wave and print the report. Plentiful experiments of many type samples are carried out using the system. It is confirmed that the system meet the performance requirements. In the end, the conclusions of this paper are given and the suggestions for further study are made.