This paper studied the back-pressure loops in the hydraulic system of an injection molding machine,and several models were established by an AMESim software through changing the damping hole and the damping ratio of relief valves.The back pressures of the pilot valve and main valve were analyzed under different conditions,which included spring stiffness,damping holes and its sizes.The simulation results indicated that a proper reduction in spring rate for the pilot valve could reduce the rise of pressure in the pre-plastic back pressure system.When the diameter of the damping orifice was reduced from 2 mm to 0.5 mm,the pressures of the upper and lower chambers in the pre-plastic back pressure valve varied within 0.02 MPa.The rise of pressure no longer took place.The damping hole not only reduced the rise of pressure in the back pressure valve but also improved the stability of the hydraulic control system.%以注塑机液压系统中背压回路为研究对象,利用AMESim软件搭建模型,通过改变溢流阀阻尼孔以及改善溢流阀阻尼配比,数值模拟背压阀中不同弹簧刚度、有无阻尼孔以及不同阻尼孔大小条件下先导阀与主阀压力变化情况.结果表明,适当的减小先导阀的弹簧刚度可以改善预塑背压系统中压力上升的问题;当阻尼孔直径由2 mm减小到0.5mm时,预塑背压阀上、下腔的压力变化均在0.02 MPa以内,且没有压力上升的趋势,可通过改变增加阻尼提高液压控制系统的稳定性.
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