Research On Dynamic Displacement And Tension Of Wire Rope In Multi-rope Friction Hoisting System

Mine hoisting system is an important part of coal production activities.With the increase of mining depth,the safe operation of multi-rope friction hoisting system,especially the safe operation of hoisting wire rope,has been widely concerned.The wire rope of the multi-rope friction hoisting system is pulled by the friction wheel,connected with the hoisting container through the head sheave,and runs up and down the shaft track.Longitudinal vibration of hoisting wire rope causes tension change of wire rope.At the same time,with tension and change the excitation of head sheave swing,it is easy to cause violent vibration of wire rope between friction wheel and head sheave(abbreviated as string rope).This paper takes wire rope of multi-rope friction hoist system as research object.Combining with theoretical modeling,signal simulation and actual measurement analysis,Natural frequency,excitation and wire rope tension characteristics of hoisting system are studied.The characteristics of transverse dynamic displacement and longitudinal tension of the string rope are analyzed.Based on the vibration information of wire rope,the method of obtaining the tension of wire rope is given.The factors influencing the accuracy of dynamic displacement and tension are discussed.It overcomes the problems of inconvenient installation and maintenance of the traditional multi-rope friction hoisting wire rope tension measuring equipment.Firstly,the characteristics of natural frequency and excitation of multi-rope friction hoisting system are analyzed.The models of longitudinal vibration and transverse vibration of wire rope for multi-rope friction hoisting system are established.This paper analyzes the longitudinal vibration frequency characteristics of the hoisting wire rope,the correlation characteristics between the tension of the wire rope and the transverse vibration frequency of the wire rope,and the excitation interference factors of the hoisting system.Secondly,the transverse vibration displacement measurement and dynamic characteristics of string rope of multi-rope friction hoisting system are studied.Considering the weak light condition and the problem of obtaining the edge of the string under direct sunlight,the near-infrared camera is selected as the vibration displacement measurement equipment of the string rope.The segmentation and filtering method of wire rope image is studied.Furthermore,an infrared light source is used in combination with a near infrared camera to obtain the transverse vibration displacement of the string rope through contour fitting.It simplifies image processing and overcomes the problems of background interference and direct sunlight.The transverse vibration displacement data of the string rope is obtained,and the dynamic displacement characteristics of the string rope are analyzed.The all-weather measurement of the vibration displacement of the string rope in the multi-rope friction hoisting system is realized.Thirdly,the time-frequency characteristics of the dynamic displacement of the string rope in the multi-rope friction hoisting system are studied.When the timefrequency analysis method of wavelet transform has high resolution,there are some problems,such as energy concentration and excitation frequency interference,etc.Simulation and practical analysis are carried out.A VMD-SWT time-frequency analysis method is used.The variational mode decomposition overcomes the problems such as the modes superposition of empirical mode decomposition,and decomposes the simulation signals and the measured dynamic displacement signals of the string rope.Then,the time-frequency analysis of the Synchrosqueezing Wavelet Transform is carried out.The natural frequency of the transverse vibration of the string rope is obtained by using the multi-step frequency variance calculation.Finally,the tension characteristics of wire rope in multi-rope friction hoisting system are studied.The tension of the loading section,unloading section,acceleration section,constant speed section and deceleration section of the top and bottom string rope is analyzed by the method of time-frequency analysis in this paper.The variation characteristics of tension at different sections and the tension calculated by frequency at different sections were studied.The change of tension of each wire rope and total tension of wire rope in two cycles of top and bottom string rope is analyzed.The analysis results show that the tension of wire rope obtained by time-frequency analysis method basically meets the tension measurement of multi-rope friction hoisting wire rope,which is helpful for the research of obtaining the tension of wire rope by its vibration.There are 90 figures,2 tables,76 references in this thesis.