ELECTROMAGNETIC ON-LINE TESTING OF ROLLED PRODUCTS AND TUBES. PROBLEMS AND SOLUTIONS.
Sever technical requirements are imposed on the flaw detection equipment in the process of on-line testing of rolled products and tubes. That is why, in addition to commonly used testing methods, electromagnetic methods (i.e. eddy current and magnetic) are widely used in the process of metal products fabrication. Most widely are used the flaw detectors with encircling eddy current transducers (ECT). Continuously increasing quality requirements towards testing procedures and equipment explain necessity to develop new examination methods and instruments.In the paper will be presented two methods on enhancement of signal-to-noise ratio and rotating measuring winding of attached type) providing reliable detection of long screen (used for tubes diameters 100÷220mm) or additional noise suppression channel. As a signal source for the last one used is an additional differential pair of measuring winding with dia. Dnoise bigger than one of the basic winding used for defect evaluation (φDnoise>>φDdefect.).Signals generated by noise on both windings are aligned and subtracted on summator while signals from defects induced only in basic winding are separated for further processing. In Discussed is the technique of eddy-current and magnetic testing methods combination for systems with attached type transducers. Moving tube is magnetized through by transverse constant magnetic field. Magnetic leakage field over defects is measured by means of Hall sensors set. Revealed defects are classified as surface (signals from ECT and Hall sensors) and internal ones (signals only from Hall sensors).Developed industrial eddy-current flaw detectors VD-41P and VMD-30N (combines eddycurrent and magnetic methods) passed practical trails at leading pipe-mills in Russia, Ukraine, Moldova, Kazakhstan. The examination reliability reaches 93-95% in comparison with previous level of 70-80%.
eddy-current flaw detector encircling transducers on-line inspection noise-tosignalratio examination reliability
Yuri K. FEDOSENKO
JSC Spectrum - RIIMoscow, Russia
国际会议
第十七届世界无损检测会议(17th World Conference on Nondestructive Testing)
上海
英文
2893-2900
2008-10-25（万方平台首次上网日期，不代表论文的发表时间）