| Electro-hydraulic vibration exciters,mainly used to generate degree of formal and regular excitation force.have as advantages of stepless adjustment of frequency,strong self-adaptability,and high excitation efficiency of vibration.Electro-hydraulic vibration exciters have an important position in scientific research and engineering applications.They have been widely used in vibration tests of aerospace,environment tests of mobile machinery,vibration tests of engineering and materials,and seismic resistance tests of buildings.The research on electro-hydraulic vibration exciters is advancing toward the goal of vibration characteristics with high excitation frequency and large excitation force.Electro-hydraulic vibration exciters controlled by rotary valves have become an important form of electro-hydraulic exciters with the advantages of compact structure and stable operation.Currently the linear reciprocating motion of the vibration box of mechanical grinding devices used for metal surface nano-crystallization generally achieved by using an eccentric driven by a motor.The mechanical grinding devices used for metal surface metal nano-crystallization have the problems of low frequency,heating,fixed frequency.To overcome the above shortcoming,this paper proposed a mechanical grinding device that the way of vibration is a linear reciprocating motion of the hydraulic cylinder driven by the electro-hydraulic exciter.This paper studied the dynamic characteristics of the rotary valve of the electro-hydraulic vibration exciter based on the mechanical grinding device using an electro-hydraulic vibration exciter to drive the hydraulic cylinder.It mainly studied the hydraulic vibration system composed of the rotary valve and the hydraulic cylinder.This paper studied the dynamic characteristics of the rotary valve in the electro-hydraulic vibration exciter using a combination of theoretical modeling,numerical simulation and experimental verification.This paper designed a rotary valve structure,elaborated the working principle,established the model of the flow area of the rotary valve and the theoretical model of the hydraulic system composed of the rotary valve and the hydraulic cylinder,analyzed the dynamic characteristics of the flow field of the rotary valve by the way of a CFD numerical simulation,revealed that the internal flow characteristics of the rotary valve,and designed the experiments for indirect verification.Finally,this paper obtained the dynamic characteristics of the rotary valve.It will provide a degree of guidance for the design and related research of rotary valves of electro-hydraulic vibration exciters in the future,and a degree of engineering significance and scientific research value for the development of electro-hydraulic vibration exciters.The main research work of this paper is as follows:(1)Firstly,this paper elaborated the working principle and performance requirements of the electro-hydraulic vibration exciter,designed the physical model of the rotary valve,introduced the structural composition and working principle,and described the model of the hydraulic system composed of the rotary valve and hydraulic cylinder.(2)This paper derived the theoretical model of the dynamic characteristics of the rotary valve based on the working principle of the hydraulic system composed of the rotary valve and the hydraulic cylinder,solved the above mathematical model with a fourth-order Runge-Kutta algorithm at different frequencies,and analyzed the characteristics of displacement,speed and acceleration of the load of the hydraulic system composed of the rotary valve and hydraulic cylinder.(3)This paper performed transient simulation on the dynamic process of the rotary valve at different frequencies using the CFD simulation method,including establishing the flow field model of the rotary valve port,accomplishing the verification of the independence of the grind and the verification of independence of time steps.The transient simulation of the rotary valve port analyzed the pressure characteristics,speed characteristics and velocity streamline characteristics of the rotary valve.(4)This paper established the experiment platform of the hydraulic system composed of the electro-hydraulic vibration exciter and hydraulic cylinder,measured the parameters of the load at different frequencies,including displacement,velocity and acceleration,analyzed the above parameters of load combining the theoretical calculation results and transient simulation results,demonstrated the correctness of the theoretical calculation results,verified indirectly the reliability of the transient simulation results of the rotary valve,obtained the dynamic characteristics of the rotary valve. |
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