Impact Dynamic Behaviors Of Mine Hoisting Rope During Loading Process

Wire ropes have been widely used in mine hoist system due to their light weight, low bending stiffness and high tensile strength. The safety and reliability of the hoisting rope are important for guaranteeing the mine hoist's stability, efficiency and safe operation. In the course of mine hoisting, the loading operation of hoisting conveyance is the premise of the transfer for personnel and material from the underground to the ground such as the skip and the cage loading. However, the abrasion and rupture of wires in the hoisting rope was also resulted from the loading process. The skip is often over-weighted without measure hopper and the process of the cage loading large or super loads is inefficient, which have not been resolved. Therefore, the study on impact dynamic behaviors for mine hoisting rope during loading process is beneficial to design of auxiliary safety equipment such as the fixed-weight loading equipment for main shaft and the cage supporting device for auxiliary shaft, which is also useful for evaluating the strength of internal wires in the rope. In this paper, the theoretical analysis, simulation and experiment are combined to investigate the impact dynamic behaviors of mine rope during hoisting conveyance loading. The main research work and new ideas are summarized as follows:Considering the effect of head sheave and hoisting rope string, according to Hamilton principle, the mechanical model of the coupled longitudinal-torsional vibration for hoisting rope were built. In order to compare with the continuous coupled model, two discrete coupled models of the hoisting rope respectively based on the concentrated-mass and the method of finite element were built. By the numerical calculating, the results show that three models and their calculating methods are reasonable, and the continuous longitudinal-torsional coupled model could be used to investigate the impact dynamical behaviors of the mine hoisting system during loading.In order to master the impact dynamical behaviors of the hoisting rope during the skip loading, the longitudinal-torsional coupled models were built with quick and slow loading. According to the two hypotheses of transient and stable, the method of the frequency and response was discussed for the variable-mass coupled vibration system. And then, the impact dynamical behaviors of the skip with quick and slow loading were obtained. Finally, the optimum residual delay time for accelerated skip hoisting was proposed, and the fixed-weight system for the main shaft was discussed.In order to resolve the problem of frequent adjustment of the cage during supporting and strong rebounding, the coupled models were established during the cage supporting on the swing deck and the elastic supporting device when the loads was pushed into or out. The method of solving the hoisting rope's dynamical response was proposed and the dynamical behaviors were obtained for the hoisting rope with variable length. The technology of the cage supporting with different loads was discussed in order to enhance the loading efficiency and the safety of the hoisting system.Considering the deformation of the wire rope's fiber and basing on the theory of wire rope by Costello, the linear stiffness coefficients of strand and rope respectively with arbitrary number of strands and wires were deduced. According to the longitudinal strain and the torsional angle per unit length for the hoisting rope, which obtained by coupled longitudinal-torsional models, the stress of internal wires was obtained and the method of fatigue strength was discussed finally.