Simulation Study Of Hydraulic Cylinder Speed Control System Based On High-speed On-off Valve

Nowadays,with the rapid development and wide application of computer,as a global industry,hydraulic industry also go to the digital development in constant with the computer.Therefore,in the hydraulic system,proportional valve,digital valve and servo valve are used as amplifiers.As an important component of hydraulic system,valve affects the performance of the whole system,It even affects the superiority,reliability,efficiency and life of the whole machine.Therefore,the selection of the valve is particularly important.High speed on-off valve is controlled by a PWM signal of the electromagnet to push the spool.High speed on-off valve only have two forms that are "on" and "off".As long as control frequency or pulse width of PWM,we can control the time "on" and "off".High speed on-off valve is widely used because of its simple structure and fast response.In this paper,the speed control of high speed on-off used in high-speed ball spinning system under the pressure of the platform is analyzed and the performance of the feasibility study.Establishing a simple hydraulic system which is Formed by the high speed on-off valve instead of other servo valve with high efficiency,economy,simple structure,easy operation as the starting point.The high speed on-off valve control flow independently,and provide a reference for the optimization of ball spinning machine.According to the principle and working condition of high speed ball spinning machine,determine the load of the hydraulic system components,hydraulic cylinders,maximum operating speed,and so on.And design and calculate size of the hydraulic cylinder.Determine the operating pressure and required flow rate of hydraulic system.In order to verify the feasibility and stability of the hydraulic system to control the hydraulic cylinder,basic equation are established.By building Simulink mathematical model of open loop system,get velocity curve of hydraulic cylinder,and so on with variable duty cycle and constant load.And velocity curve of hydraulic cylinder with constant duty cycle and variable.Analyse and summarize the influence of duty radio and load on the system.The transfer function of the closed-loop system is established.Build transfer function model in Simulink and draw Bode diagram to determine the stability of the closed-loop system.The simulation results show that the hydraulic system of hydraulic cylinder speed control is feasible,and the system is stable.But when the load varies according to the linear variation,it has a great influence on the speed of the hydraulic cylinderIn process of ball spinning,changing axial force of ball spinning make the feed rate change.And the feed speed is whether stable or not affects the spinning precision directly.To determine the method of eliminating the effect of load change on hydraulic cylinder speed,it is the PID controller.Model of AMESim can simulate the simulation curve of hydraulic cylinder speed under different load variation and setting the PID parameter.The results of Simulink show that this method can make the speed free from the effect of the load and remain in a fixed value.It can further improve ability of the system of resisting changing load,ensure the feeding speed of the spinning is unchanged,and further improve the precision of spinning.Finally,Compare the displacement history of hydraulic cylinder with solenoid valve with the simulation results without the solenoid valve.And analyze the reason of the fluctuation.