Design And Research Of Eddy Current Testing System For Steel Tube

Steel tubes are widely used in various fields of the national economy.However,due to the harsh working environment,steel tubes are prone to corrosion,fatigue and even fracture,which have a serious impact on industrial production and even endanger the life safety of employees.Therefore,it is very necessary to carry out pre-service inspection on steel tubes.At present,the most commonly used method for quality testing of steel tube is eddy current testing method,which has the advantages of high detection sensitivity,simple quality evaluation method,noncontact measurement,easy to realize automation,etc.In view of the influence of velocity effect on testing effect in eddy current testing of steel tubes,this paper adopts a combination of simulation and experiment to conduct relevant research.The specific research work is as follows:Firstly,the research background and significance of eddy current testing for steel tubes are summarized,and the basic theory of eddy current testing method is briefly explained.The threedimensional model of the steel tube to be tested and the eddy current testing coil is established by using ANSYS Maxwell finite element simulation software.The intensity variation of magnetic field and eddy current field at the defect position of the steel tube under different testing speeds is explored.The relationship between different types of defects and the magnetic induction intensity is studied with the magnetic induction intensity as the characteristic value.When the defect size is fixed and the detection speed increases,the variation trend of magnetic field strength and eddy current strength is analyzed,and the influence of velocity effect on eddy current detection response signal is fundamentally studied,which lays a theoretical foundation for subsequent experimental research.Then,the eddy current testing platform and testing system for steel tube are built.The testing platform is divided into two parts: mechanical structure and electrical control system.After analyzing the 50 mm diameter steel pipe studied in this topic,the design scheme of mechanical structure is determined,and the key components are described in detail,including the steel pipe conveying mechanism,the detection probe installation mechanism and the steel pipe pressing mechanism;The electric control system can realize infinitely variable speed,and the influence of speed effect on eddy current testing effect can be easily studied.The principle of the control system is analyzed,the motion parameters of the drive shaft are determined,the hardware selection of the electrical system is carried out,and the actual wiring debugging of the electric control cabinet is carried out at last.Detection system mainly includes signal generator,DC power supply,power amplifier module and data acquisition module,the power amplifier module adopts chip and circuit principle has carried on the detailed analysis,finally set up the actual detection system,and up and testing platform in this topic design of the steel tube eddy current testing equipment.Finally,the experimental study of steel tubes with different defects is carried out,and the eddy current response signals are obtained.The original signals collected are filtered and averaged synchronically,and the signal is analyzed and studied with the peak value of signal amplitude as the characteristic value.The experimental results show that in the static state,with the increase of the defect size,the disturbance of the local magnetic field at the defect location increases,and the signal peak value increases accordingly.When the static detection is changed to the dynamic detection,the signal peak values of the through hole defects,the outer wall depth defects and the width defects all increase significantly,indicating that the generation of Motion Induced Eddy Current improves the defect signal strength compared with the static detection.When the detection speed increases to 1m/s,the signal peak value of each defect approximately shows a linear increase trend,and when the defect size is large,the difference of the defect signal peak value is great,which is conducive to the realization of the differentiation of such defects.However,when the defect size is small,the difference of the peak value of defect signal is small,which is similar to that in static detection,making it difficult to distinguish tiny defects in dynamic detection.