Research On The Pressure Close-loop Control Of Hydraulic Press Based On Electro-hydraulic Proportional Technology

Hydraulic press as a processing equipment, is widely used in various forging, hot pressing, powder molding, extrusion pressing, superplastic forming, drawing shear and other mechanical industry. In terms of their control, include three parameters control: pressure, speed and position control, and the pressure control is particularly important. It directly affects the quality of processed products, productivity, and pump power. But up to now, the stability, control accuracy and System response speed of the hydraulic press is generally not high, the device itself for application environments with less demanding and accuracy, mostly still use traditional switching valve.But with the rapid development of modern industry and manufacturing refinement, the hydraulic press needs increase the integrated control performance. So,the traditional switch control and closed-loop electro-hydraulic proportional control of the single close-loop hydraulic press has been unable to meet current demand. In this context, the paper researches four-column YA32-315 hydraulic press ,and adopt hydraulic press pressure double close-loop control system based on electro-hydraulic proportional technology. Mostly, do the following work :1. Analyse the composition structure and hydraulic process principles of four-column YA32-315 hydraulic press, and elaborate on the process of its hydraulic system and the principle of the action.On this basis, closed-loop pressure control system is adopted based on electro-hydraulic proportional technology to improve the original system.2. To the improved hydraulic system requirements, respectively, the structure and principle of the electro-hydraulic proportional directional control valve and electro-hydraulic proportional relief valve are analyzed, and construct single and double closed loop control system of two kinds of valve and on the basis, construct entire electro-hydraulic proportional pressure close-loop control system.3. Build mathematical models of the of electro-hydraulic proportional relief valve for controling the pressure and gain their transfer functions. And analyze the transfer function and PID controller pressure control system principle. On the basis, obtain single close-loop and double close-loop control system transfer functions of electro-hydraulic proportional pressure control system.4. According to transfer functions of electro-hydraulic proportional pressure single and double close-loop control systems, do the simulation to the system using the MATLAB software. Simulation results show that the control accuracy of the double close-loop control of hydraulic pressure control system is significantly improved. The response time of system is reduced,and greatly improve the efficiency of hydraulic press. Can meet the current requirements for the high control performance in industrial areas.