Research On The Magnetic Characteristics Of The Magnetic Flux Leakage Detection Of The Tank Wall-climbing Robot

Storage tank serves as the most common equipment in petrochemical industry,the tank wall is easy to produce all kinds of defects then harm to life and property security because of the medium is inflammable,explosive,easy to corrosion,with the combination of pressure in tank&the outside factors.In order to ensure the safety of the storage tank,the tank should be regularly checked and cleaned.The traditional artificial methods exists many shortcomings,so the automation instrumentations will replace artificial.For the reason,this article take the vertical cylindrical storage oil tank wall as the research object,and designed a MFL climbing robot to storage tank wall defects.However the cylindrical tank which volume is larger than 1000 m3 adopts variable cross scctions,different wall thickness requires different magnetization.Based on the volume of 500?3000m3 cylindrical tank for the object,this thesis designed a adjustable magnetization mechanism which is suitable for tank wall defects MFL to different thickness.And summarized the characteristics of defect magnetic leakage field for the magnetization mechanism,which are used for defect recognition.So,the thesis mainly includes program design,mechanical design,magnetic circuit design.And studied the magnetic characteristic of the adjustable magnetization mechanism by dynamic and static combining with theories and simulations,then completed the experiments of the prototype.Firstly,through analyzing the characteristics of the storage tank and the testing requirements,the thesis puts forward the design indexs,and chooses the adsorption mode,walking mode&testing mode.Then emphatically discusses the structural design of achieving magnetization,adsorption,walking&MFL.Among them,the adjustable magnetization mechanism can realize the MFL testing to tank wall within a certain scope of thickness.Secondly,the formation&features of defects magnetic leakage field and the principle of MFL were discussed theoretically.The magnetic leakage field theories mainly include nalytical analysis,numerical analysis and Foster theory.So,the judgments for simulations and experiments of MFL characteristics were provided by theory analyses.Thirdly,the velocity influence on MFL is proposed,and low-speed MFL were analyzed by the electromagnetic simulation software Ansoft.Then analyzed the influences of the signal picking up and the defects static-testing or dynamic-testing results by simulations,so the characteristics of MFL mechanism designed in this thesis were summarized.Fourthly,the corresponding verified experiments including the magnetized effect of magnetization mechanism&the magnetic flux leakage tests of defects library were made by prototype.The simulations and experiments show the consistent rules to magnetic leakage field and magnetic characteristics,the prototype can magnetize the tank wall in a certain thickness range,and tested all inside defects and some outside defects.