| With the depletion of shallow coal resources,mineral resource mining is developing to deeper levels and larger scale.Among newly built large-scale vertical shafts in China,the maximum mining depth has exceeded 1500 meters.As one of the pivotal equipment in coal mining and transportation,the dynamic performance of the vertical shaft liftting system,such as alternating stress levels during loading and transporting,directly affects the safety level and production efficiency of the vertical shaft lifting system.Although the traditional friction lifting system can achieve heavy load lifting,it has the problem of limited lifting depth.Although the traditional winding lifting system can realize deep well lifting,the load weight it can transport is limited to a small range.In order to solve the problem that the existing lifting system cannot simultaneously satisfy the transport at ultra-deep levels and lift a heavy load,and further improve the performance of effective load rate,hoist efficiency,and safety that decrease rapidly with the increase of lifting height,it is of great significance to study the related dynamic characteristics and prestress control methods of the existing vertical shaft lifting systems.The thesis focuses on dynamic displacement and alternating stress fluctuation characteristics in friction lifting systems.In order to suppress the rope vibration and alternating stress amplitude,the prestress control methods are proposed,thus providing a new idea for reducing the dynamic displacement amplitude and alternating stress level,as well as a theoretical basis and technical support for ultra-deep mining and heavy-load transportation.Firstly,in order to accurately describe the dynamic response of the friction lifting system during loading,the 1600 meter-deep-floor-type and tower-type friction lifting systems are taken as the research object respectively,as well as dynamic models of catenary-head sheave-vertical rope-skip coupled vibration and vertical rope-skip vibration are built,respectively.The influences of the catenary length on vertical rope dynamic characteristics,as well as the effects of the lifting depth on skip vibration displacements during loading,are obtained through analysis and comparison,thereby laying the foundation for subsequent analysis.Aiming at the large amplitude of skip vibration displacement in the loading process of the friction lifting system in a deep well,the buffer bearing device is designed.Through theoretical analysis,the influence law of different supporting stiffness and damping on the stability of the skip during loading is explored,which provides a theoretical reference for the application of the buffer device to realize the stability of the skip position in practical engineering.Furthermore,a boundary disturbance observer is designed for the loading impact uncertainty in the actual loading process,and the boundary controller is designed by combining the backstepping method and barrier Lyapunov function,which ensures the rope stress fluctuation amplitude reduce to about 1/17 of the one without control and the skip position stable near the desired position.Then,in order to explore the dynamic response characteristics and prestress control methods of the friction lifting system during operation,the static and dynamic analyses are carried out respectively.Firstly,the fluctuation characteristics of rope stress are analyzed from a statistical point of view,and a reasonable control scheme is designed to adjust the tension of the tail rope.Therefore,the rope stress fluctuation amplitude can be suppressed within the variation range of its dead weight under the whole cycle operation of the lifting system,which provides a theoretical reference for suppressing the fluctuation amplitude of the lifting rope stress by adjusting the tension of the tail rope.Then,the dynamic models of the coupling vibration of the driving drum-catenary-head sheave-vertical rope-skip-tail rope in the floor-type friction lifting system and the coupling vibration of the driving drum-lifting rope-skip-tail rope in the tower-type friction lifting system are established.The influence of the tail rope on the dynamic response of the lifting system is analyzed when the tail rope is considered as different structures,and the influence law of tail rope pre-tightening force on the dynamic characteristics of the lifting system is explored,which provides a theoretical reference for the controller design to restrain the amplitude of dynamic stress fluctuation of wire rope based on the tail rope tightening drive.Finally,considering the structural characteristics of the winding lifting system and the friction lifting system,a composite lifting system combining the characteristics of the two types of lifting systems is proposed.The theoretical model is analyzed and tested by building the simulation experiment platform of the composite lifting system.Compared with the original friction lifting system,the maximum head rope dynamic stress fluctuation amplitude in the proposed composite lifting system can be reduced by nearly half.Aimed at the problem that the skip vibration amplitude is too large during loading,an adaptive boundary controller is proposed to realize the control input through the head sheave position adjustment,which ensures the stability of the closed-loop control system.Aiming at the resonance caused by the crossover between the natural frequency and the excitation frequency of the catenary during operation,it is proposed that the length and force of the catenary can be changed by adjusting the up and down positions of the head sheave,and a reasonable control method is designed to avoid the resonance area of the catenary in operation,which provides a new idea for controlling the transverse vibration of the catenary.This thesis has 89 figures,10 tables,and 153 references. |
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