With the development of the hydraulic system of the injection molding machine towards Middle and high pressure, the pilot relief valve is widely used in the control oil circuit of the hydraulic system of the injection molding machine.

In practice, in order to maximize its efficiency, maintenance of the control system, accurate and timely diagnosis and troubleshooting of the pilot relief valve is a key link. The failure of the pilot relief valve will cause the injection molding machine to fail to operate. According to the phenomenon, the reasons are as follows: the spring of the valve core of the pilot valve is broken, the orifice is blocked; the seal of the valve port of the pilot valve is poor, and the main valve core is stuck, etc. The corresponding elimination measures are replacing or adding a flat pad at the broken part for emergency use, cleaning and dredging; grinding or breaking the oil circuit for emergency use, grinding and cleaning.

Unstable pressure limit: the pilot relief valve is unstable pressure limit, which means that the hydraulic system pressure is low or high, the hydraulic actuator is weak or the oil pipe, pump body and valve body burst. The causes of this fault are: improper pressure adjustment; bent or soft spring of pilot valve spool; dirty oil or poor flow of oil. The corresponding elimination measures are readjustment, correction, padding or replacement, replacement and cleaning. The instability of the pilot relief valve is a gradual failure, and the failure of the pilot relief valve is a sudden failure. After troubleshooting, the pressure controlled by the pilot relief valve should be readjusted according to the pressure limited by the injection molding machine system.