| Camshaft as one of the important parts of the engine,its quality,safety and longevity have a crucial influence on the performance and reliability of the engine.Camshaft subjected to alternating load,large contact stress and high relative sliding speed at work,so micro cracks produced by camshaft grinding significantly reduce the performance and life of the camshaft,non-destructive testing of camshafts is of great value.This article takes the hollow camshaft as the research object and propose magnetic flux leakage detection method applied to micro crack detection of camshaft,analyze the leakage magnetic field characteristics of micro cracks of camshaft through ANSYS,explore the influence of crack size and lift-off value on detection,considering the curvature of the cam,magnetic heads are selected as magnetic sensing elements of the system;Select circumferential magnetization method for hollow camshafts,design U-shaped yoke circumferential magnetization device,optimization parameters through ANSYS;Considering changes in thickness,curvature,and normal direction,design three degrees of freedom tracking mechanism for magnetic leakage probe to drive probe enables effective scanning of the cam surface;After analyzing the difference between frequency components of crack magnetic flux leakage signal and tracking abnormal signal,optimized signal processing circuit by Multisim,removing the effect of abnormal signals and increasing signal to noise ratio.Combining previous analysis and requirements,propose a method of camshaft camshaft rotation and probe fitting,design flux leakage detection system for various specifications of camshaft,formulate high-speed automated inspection process.Tested to prove,the camshaft flux leakage detection system can stably and efficiently complete the automatic nondestructive inspection of the camshaft,expanded the application of non-destructive testing of magnetic flux leakage in the field of automotive parts. |
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