| The emulsion pumping station is the power source of comprehensive mechanized mining equipment such as hydraulic support on the working face.Its performance directly affects the life safety of coal miners,the service life of the equipment and the working efficiency of mining.With the continuous advancement of science and technology,large-scale and super-high-lift hydraulic supports have been successfully developed and applied to underground production.The mining methods and methods have also gradually moved from early mechanized mining to intelligent and unmanned mining.Higher requirements are placed on the liquid supply capacity of the pumping station liquid supply system,ie the stability,reliability and timeliness of the liquid supply.The SAP-type integrated intelligent liquid supply system has been able to realize rapid liquid supply,multi-range control of pressure and remote intelligent control.The electromagnetic unloading system is the core component of the integrated pressure control system of the fully mechanized mining face,with automatic pressure regulation and fast flow.Matching and system energy saving,high efficiency and other aspects play an important role.This paper studies and analyzes common electromagnetic unloading systems,compares and analyzes the structure and working principle of K-type electromagnetic unloading system and S-type electromagnetic unloading system,and finds these two series of electromagnetic unloading through tracking test in fully mechanized mining face.In the actual production application,the load system has the problems of poor dynamic response,large pressure pulsation,serious cavitation damage and the like.In order to better meet the intelligent control of the hydraulic system hydraulic pressure of the fully mechanized mining face,the rapid movement of the hydraulic support,and the high reliability of the fully mechanized mining equipment,and improve the stability of the electromagnetic unloading system,this paper mainly selects the S-type electromagnetic unloading.The system conducts joint comparative analysis by theoretical derivation research,software simulation and other methods to study the influence of different parameter matching on the performance of electromagnetic unloading system.Firstly,this thesis uses theoretical derivation and calculation methods for theoretical analysis.Static characteristics analysis and dynamic characteristics analysis are carried out on the main control parts of electromagnetic pilot valve,mechanical pressure regulating valve and unloading main valve in electromagnetic unloading system,and static mechanics is derived.Equations and dynamic equations are used to establish mathematical models.Through analysis,it is considered that the electromagnetic control signal(electromagnetic force)response time,the pilot valve spool stroke,the mechanical pressure regulating valve seal diameter,the orifice diameter parameter,the unloading spool spring stiffness,etc.all affect the dynamic response characteristics and pressure pulsation of the electromagnetic unloading system.Key parameters.Secondly,the simulation software AMESim is used to establish the model of the electromagnetic unloading system for simulation analysis.The influence of the matching relationship of different key parameters on the system pressure fluctuation and response characteristics of the electromagnetic unloading system in electromagnetic control mode and mechanical control mode is analyzed.The simulation results show that the parameters such as the diameter of the orifice,the diameter of the valve seat of the mechanical pressure regulating valve,and the faster the response speed of the electromagnetic pilot valve have great influence on the stability of the electromagnetic unloading system.The unloading system can be improved by reasonably matching the parameter relationship.stability.Finally,the flow field characteristics of the emulsion medium in the valve chamber at the unloading spool are simulated by the computational fluid dynamics software Fluent.Comparing and analyzing the cavitation flow movement of the medium in the valve cavity under different opening degrees,namely velocity vector distribution,pressure gradient distribution and gas phase distribution.It can be seen from the simulation results that the smaller the opening degree of the unloading valve core,the greater the throttling effect caused by the flow of the medium through the valve port,the greater the change of the velocity gradient,the larger the pressure difference between the front and the back,the more serious the cavitation phenomenon,the cavitation damage The more obvious.By matching the design parameters of the valve sleeve and the valve core,the design of the valve core structure parameters is optimized,and then the simulation results before and after the optimization are found.After the optimization of the valve core parameters,the gas phase volume fraction and the gas phase distribution area in the unloading area are significantly reduced,and cavitation The phenomenon inducing the phenomenon is reduced,which can effectively reduce or prevent the occurrence of cavitation damage.Through theoretical calculation and simulation analysis,this paper can effectively improve the dynamic response of the electromagnetic unloading system,the pressure pulsation and the serious cavitation damage by reasonable matching between the key parameters.The overall stability and reliability of the electromagnetic unloading system have a certain role in promoting. |
PDF Full Text Request