Research On Emergency Braking Characteristics Of Hoist Based On Three-way Proportional Pressure Reducing Valve

The mine hoist is responsible for the lifting and transportation of personnel,equipment and minerals,which directly affects the safe production and efficiency of the mine.As the mining depth continues to increase,there are higher requirements for the lifting speed,which will also affect the dynamic characteristics and braking performance of the hoisting system during emergency braking process.During operation,the hoisting system has obvious influence on the braking process because of hysteresis,inertia impact and wire rope flexibility.The constant deceleration braking system of the hoist mostly uses a pressure sensor and an electro-hydraulic proportional directional valve to form a pressure closed loop.When the pressure sensor fails,the pressure of the hydraulic cylinder will be uncontrollable,which poses a serious safety hazard.At the same time,there is a certain coupling relationship between the hoisting system and the braking system,resulting in serious shock and vibration of the system during the braking process,it is easy to cause safety problems such as slippage,breakage of the wire rope and even the cage falling.Therefore,the safe and stable operation of the hoist,the improvement of the dynamic response of the braking pressure,and the reduction of shock and vibration are the key problems that need to be solved in our current mine.In view of the above problems,this dissertation took JKM3.5×6Z(?)tower friction hoist as the research object,and established the mathematical model of the hoist through the generalized Hamiltonian principle.A hydraulic system model based on a three-way proportional pressure reducing valve was designed through Matlab/Simulink,and a dynamic simulation modeling of the tower mount hoist was established through Recurdyn.Using the interface configuration between the two software,the hoisting system was combined with the hydraulic braking system,and a complete electro-hydraulic rigid-flexible coupling dynamics co-simulation model was established based on the double closed-loop PID controller of speed and pressure.The simulation results were compared with the field test results to verify the accuracy of the co-simulation model.Then,the three-way proportional pressure reducing valve and the main control valve currently used in mines were separately simulated for emergency braking conditions.Finally,the simulation model was used to analyze the effect of operating parameters on the emergency braking process,and the dynamic changes of the hoisting system and the braking performance of the hydraulic system were studied.The results show that:(1)The established rigid-flexible coupling tower friction hoist co-simulation model can reflect the key dynamic characteristics of the hoist system in the braking process and the transmission mechanism of the dynamic friction force of the system.(2)Compared with the braking system based on electro-hydraulic proportional directional valve regulation,the braking process based on the three-way proportional pressure reducing valve has a faster response speed,better followability,vibration damping and antidisturbance ability.(3)The operating parameters will have a certain impact on braking performance and system dynamics during emergency braking process.During the emergency braking process under lifting conditions,when the lifting load increases or the braking deceleration decreases,the braking pressure will increase accordingly,and the brake loosening phenomenon is easy to occur.The vibration of the cage after parking will increase as the load,and the stability of the system will deteriorate.During the emergency braking process under lowering conditions,the vibration and impact of cage at the initial braking stage will increase as the load.If the load or braking deceleration is too large,not only will the brake shoe be locked,but also the wire rope is more prone to slipping.For the length of the wire rope suspension on the load side,when the suspension rope is short,the braking pressure fluctuation becomes larger,and the lowering condition is more prone to slipping than the lifting condition.When the suspension rope is longer,the longitudinal vibration of the cage increases,and the system energy dissipation is slower.