Dynamic Characteristics Analysis Of High Pressure Cavity Of Hydraulic Press In Pressure-relief Process

Pressure-relief process of high pressure hydraulic cavity often produces vibration and shock. Vibration and shock can cause damage to the system, and this could seriously affect the normal work. In this dissertation, an example that complete the pressure-relief process by using cartridge valve with large flow ability is selected to carry out the modeling analysis and mechanism study of this frequent phenomenon. The main research contents and results are as follows:Firstly, based on the simplified pressure-relief system model, its mechanism is analyzed from the angle of pressure-relief essence so as to annotate the working mode, mutuality and function of internal factors within it. And a mathematical model for the pressure relief valve group is established, which provides a theoretical basis for modeling and simulation of the system by AMESim.Secondly, the simulation model for the system is established by AMESim software. Based on the pressure-relief valve group vibration mechanism analysis, key parameters that impact the vibration, the vibration measurement standard for valve group and variables to report the dynamic characteristic are determined. Then a simulation analysis of effect of the key parameters on the vibration is made, focusing on the analysis of influence of orifice diameter. Taking both the rapidity and the stability of pressure relief into consideration, the proper range and optimum reference value of these key parameters including the solenoid valve commutation interval and the diameters of three main orifices A, B, D are determined.Then a two-dimensional numerical calculation model for the main valve is established. And a numerical simulation of the valve is done by CFD software to analyze the uneven distribution and time-varying characteristic of the flow velocity, pressure and flow field within the valve during pressure relief. On this basis, the fluid internal causes of vibration in the valve and after-valve pipeline are explained.At last, the relief piping system is divided into pipe subsystem before the valve and the after-valve piping, and the influence mechanism of main valve throttling effect on pipeline resonance is studied. Based on the pipeline transmission dynamics theory, the effect of valve size and opening degree on piping resonance is discussed, which provides a theoretical reference for the main valve size selection and the opening control within the relief process.In conclusion, a detailed modeling analysis for three-stage cartridge valve group pressure-relief system is made in this dissertation, and the dynamic characteristics of each part of the system are simulated. The research results can well guide the parameter debugging work of pressure-relief valve group, which has obvious engineering practical significance. The analysis of vibration mechanism of the pressure-relief system can provide ideas for reducing vibration from the root and enrich the theory of pressure-relief vibration reduction for hydraulic press.