Design And Research On Control System Of Electro-hydraulic Proportional Control Test Bench Based On PLC

With the development of electronic technology and hydraulic control technology,electro-hydraulic proportional control technology has been widely used in the field of engineering and modern scientific research.The problems of positioning and synchronization of hydraulic mechanism realized by electro-hydraulic proportional technique and convenient,stable and accurate control of force loading process are getting more and more attention.At the same time,in industrial applications,metal materials processing and construction machinery are required more for hydraulic position control and force loading control technology.Therefore,It is very necessary to study the electro hydraulic proportional control technology.Based on the needs of teaching and research,the main task is to research and design a test bench to make an experimental research on position control and force loading control of hydraulic cylinder for teaching learning and research of electro-hydraulic proportional control technology application,and meet the requirements of the function and performance of the corresponding.A scheme is put forward based on characteristics of PLC and advantages of PWMelectro-hydraulic proportional control technology in this topic.The scheme takes PLC as the controller,the PWM proportional valve as the control element,the hydraulic cylinder as the actuator,and electro-hydraulic proportional control technology is applied to realize the position control and force loading controlof the hydraulic cylinder.Furthermore,it completes three experimental projects that includes cylinder posi tioning,double cylinder synchronization,and force loading control,and makes use of Wi ncc Flexible software to achieve real-time monitoring of test process.Firstly,the thesis introduces the composition of electro-hydraulic proportional control test bench and gives the composition and working principle of the single cylinder hydraulic positioningcontrol system,double cylinder synchronous hydraulic control system and force loading hydraulic control system,and completed the hydraulic circuitdesign and component selection corresponding.Then,the mathematical model of hydraulic position control and force loading control system is completed,and the simulation research of PID control strategy is carried out,and the simulation results are analyzed to determinecontrol strategyon the basis of valve controlled hydraulic cylinder.Finally,the hardware design and software programming of the control system of the test bench is completed with S7-300 PLC as the controller,andit is used to effectively control the test system by the control program and the PID algorithm.At the same time,the human-machine interface is edited by Wincc Flexible,andthe communication between HMI and PLC is used to display and monitor the running status of the system in real time through the Profinet communication protocol.It makes the experiment control process more simple and the result is more intuitive.After system debugging and experiments,the result indicates that the hydraulic cylinder position control and force loading control system can obtain relatively ideal static and dynamic performance by using this design scheme.The whole motion process can be monitored in real time,and Pressure,liquid level,temperature and other parameter scanbe monitored and the fault alarm can be achieved.Therefore,it can be well applied to industrial engineering and teaching experiment.