Research On The Structure Design Of Wire Rope Damage Detection Device For Hoist

As the main bearing component of mine hoisting system,wire rope’s health is an important guarantee for safe operation of coal mine.In this paper,after analyzing a large number of documents,it is found that there is little research on the structure design of excitation unit and detection unit in the existing electromagnetic detection technology of wire rope.In this paper,the structure of excitation unit and detection unit of wire rope is studied based on finite element method.Firstly,the parametric equation of the center line of the wire rope is deduced,and the three-dimensional model of the wire rope is established.Based on Maxwell’s basic theory,it is concluded that the leakage magnetic field of broken wires mainly leaks from the side of the fracture surface of it.Based on this conclusion,it is proposed that the spatial shape of leakage magnetic field of wire rope is approximately ellipsoid.The main forms of broken wires demage of wire rope are analyzed,and the damage detection standard of wire rope is expounded.Three excitation modes of wire rope are compared and permanent magnet excitation mode is selected.Four detection methods of leakage magnetic field are compared and Hall detection method is selected.Finally,the design scheme of wire rope damage detection device based on permanent magnet excitation mode and Hall detection method is established.Secondly,two existing excitation structures of wire rope are pointed out,including single-loop excitation structure and multi-loop excitation structure.Modeling and simulation are carried out to compare the magnetization performance of the two excitation structures.In view of the shortcomings of the existing two excitation structures,a ring excitation structure is designed,and its modeling and simulation are carried out.The advantages of the ring excitation structure over the existing two excitation structures in the field of magnetization performance are analyzed.Then,seven kinds of magnetic field models of leakage wire ropes with different broken wires are established.According to the model,the relationship between the leakage magnetic field characteristics of wire rope with the number of broken wires and the lift-off distance is analyzed,including the relationship between the radial component,circumferential component and axial component of leakage magnetic field with the number of broken wires and lift-off distance.According to the characteristics of leakage magnetic field of wire rope,the structure design of detection unit of wire rope is carried out.The main purpose is to design the lift-off distance of Hall element when detecting leakage magnetic field of wire rope.Finally,aiming at the serious swing phenomenon of wire rope in mine hoist during operation,a kind of wire rope following mechanism is designed to reduce the influence of wire rope swing on leakage magnetic field detection.At the same time,an experimental system is designed based on the excitation unit and detection unit of the wire rope designed in this paper,and the damage detection experiment of the wire rope with different number of broken wires is carried out.The experimental results are analyzed and verified that the excitation unit and detection unit designed in this paper have practical value for the damage detection of wire rope.