Study on appliction of electrohydraulic servo proportional valve in hydraulic system for rolling mills

This thesis studied the hydraulic servo system used on main press equipment of a multi-roller reversible cold rolling mill. Nozzle flapper type of electrohydraulic servo valve is now widely used. This type of servo valve has such problems as bad contaminating resisting ability, easy to be blocked by contaminating material and requires for highly system maintenance. These problems restricted the reliability of whole system. Aiming at solving these problems, the possibility of replacing nozzle flapper type of electrohydraulic servo valve by electrohydraulic proportional valve was raised in this paper, mathematic model for position servo system of press equipment that uses electrohydraulic servo proportional valve as the control unit was established. Dynamic analysis and simulation based on MATLABSimulink was carried out and conclusion was acquired. The study provides foundation for the design of automatic thickness control system of a rolling mill by using electrohydraulic proportional valves.