Evaluation of an electrohydraulic forge valve behavior using a CAD package

Abstract An electrohydraulic system of the type used to control the position of a forging press cylinder is studied analytically and experimentally. The main control component is a flow bypass valve that controls flow rate into and out of the main hydraulic line and is of the poppet-following type. The steady-state pressure/flow characteristic of the bypass valve with an existing seated poppet is compared with a new vee notch poppet design intended to improve the steady-state characteristic and hence the closed-loop press cylinder position response characteristic. Dynamic modelling of the flow bypass valve is then considered and the transient performance is assessed for the two poppet designs and with the valve in an idealized circuit. The complete system dynamic model is then established and a recently developed CAD package is used to simulate the position response of the press cylinder. Both poppet designs are studied, and it is deduced that there is a negligible difference in transient performance, attributable to unique features of the control system. Good comparisons between simulation and experimental results were achieved.