Research On Broken-wire Detection Device For Wire Rope Based On TMR Sensor Array And Its Application

A wire rope is widely used in many fields,such as mining,port transportation,chemical industry,metallurgy and aerospace.As working in different working conditions,wire ropes are prone to many problems,such as fatigue,damage,deformation or wire breakage,among which wire breakage is the most harmful and common form of failure modes.Therefore,it is of great significance to detect wire breakage accurately and rapidly so as to reduce or even avoid violations of personal and property safety accidents caused by wire rope failure.To overcome the deficiency of the existing wire breakage detection technology,this study designed a wire breakage detection device based on a Tunneling-Magnetoresistance(TMR)sensor array and the principle of magnetic flux leakage inspection for ferromagnetic materials.The main contributions of this dissertation are as follows:(1)A model of magnetic flux leakage calculation for wire breakage defection was established,based on the principle of magnetic flux leakage and the model of equivalent surface magnetic dipole.The tendency of different direction component of magnetic flux leakage relative to distance was analyzed,providing the theoretical basis for wire breakage defection of wire ropes by the inspection of magnetic flux leakage.(2)A Helmholtz-like coil excitation device was designed.The distribution model of magnetic induction intensity of excitation fields was established with the structure parameters of excitation device determined by calculation.Then we applied a finite element simulation software to optimize and verify the structure parameters of the excitation device.(3)A flexible TMR sensor array was designed,which improved the practicability of the device,developed and increased its detection range in both axial and circumferential dimensions.(4)We designed the signal processing circuit of magnetic flux leakage,selected chips and debugged.The upper computer program of wire breakage detection device based on Qt was then compiled.(5)An experiment platform was built to detect an oily steel wire rope with different degrees of wire breakage defects on its surface.The results of experiment indicate that the device designed has high sensitivity,high signal-noise ratio.The array elements of the TMR sensor array have good consistency.The minimum detection accuracy of the device is the breakage of a single wire within a loss of 0.4% of the metal section and the minimum axial resolution distance is 5 mm,verifying the effectiveness and practicability of the device.