Multi-field Synergy Analysis Of Alternating Hydraulic Driven Rock Drilling Machinery

The alternating hydraulic driven rock drilling machinery has the advantages of high energy utilization and wide application range.It has been widely used in metallurgy,mining,high-speed rail tunnel construction and other related industries.At present,the systemic research on alternating hydraulically driven rock drilling machinery is still insufficient,especially on aspects of the impact piston rebound characteristics and the transient impact response of the impact mechanism of the alternating hydraulic driven rock drilling machinery.In view of this situation,this thesis comprehensively used numerical analysis method,finite element method and test method to conduct systematic research on dynamic characteristics and transient impact response of alternating hydraulic driven crushing hammer.Firstly,according to Newton's second law and continuity principle,this paper establishes the dynamic model of alternating hydraulic driven rock drilling machinery impact system and oil distribution system.and obtains the nonlinear differential equation of impact system by simplifying the dynamic model.Secondly,based on the AMESim,the numerical simulation model is established and the dynamic characteristics are analyzed.The pressure,flow parameters and the dynamic characteristics of the system under different working parameters and working conditions are obtained.Using the obtained flow and pressure parameters,the distribution of flow field under the four key conditions of the distribution valve is simulated and analyzed in Fluent software.The research results show that the AMESim numerical model with the equivalent model of the impact spring stiffness and the working medium can reflect the actual working condition of the alternating hydraulic driven crushing hammer,and the impact piston motion curves solved by the numerical model is in good agreement with the ones solved by analytical model,which proves the correctness of the numerical model.During work,within a certain range of oil supply,increasing the input flow can increase the impact energy,however,when the input flow exceeds a certain value,the energy loss of the system increases and the energy utilization rate decreases.The rebound of the impact piston increases the amount of oil discharged from the system,resulting in a decrease in speed at the end of the next impact.In the process of spool movement,,the flow of oil in the distributing valve is unstable,and there is energy loss in multiple right angle corners,and some suggestions for improvement are put forward.Based on the one-dimensional elastic rod theory,the transient response of the alternating hydraulic driven rock drilling machinery's binary impact mechanism is analyzed theoretically.The transient response of the impact mechanism is simulated by nonlinear FEM program LS-DYNA,the influence of the working medium properties and impact velocity of the impact piston on the transient response is analyzed,and the dynamic drilling process of different working media is revealed.The correctness of the finite element simulation model is verified by the test method.It is found that there is a slight impact between the shank and the drill stem due to stress wave transmission and reflection,resulting in energy loss.In practice,if it is not necessary to change the length of the drill rod frequently,the threaded rod should be selected.The contact time of the initial impact between the impact piston and shank depends on the length of the impact piston,therefore,the impact piston should be designed longer for a large impact energy hydraulic rock drilling machinery.The above conclusions provide a theoretical basis for further optimizing the structure design of hydraulic rock drilling machinery...