How to repair the relief valve of the hydraulic press

The relief valve is the main pressure control valve in the use of hydraulic press, which plays a role of constant pressure relief pressure regulation, then if we want to overhaul the relief valve, what should we do? In fact, we must first know the role of the hydraulic press in order to better repair.

1. When regulating the relief system of the four-column hydraulic press, the throttle or speed regulating valve is often set on the oil inlet or return circuit of the quantitative pump, so that a part of the pump oil enters the hydraulic cylinder, and the excess oil must flow back to the tank through the relief valve, the relief valve is in the normally open state of its setting pressure, and the pre-tightening force of the spring is adjusted. It also regulates the working pressure of the system.

2, the hydraulic press system using variable pump oil supply, there is no excess oil in the system to overflow, the working pressure is determined by the load, then the relief valve in parallel with the pump only need to be opened when overload, to ensure the safety of the system, so the relief valve is also known as the safety valve is normally closed.

3, hydraulic press adopts pilot relief valve pressure control quantitative pump, when the valve's external control port is connected with the oil tank, the main valve core can be quickly lifted when the inlet pressure is very low, so that the pump is unloaded to reduce energy loss, when the electromagnet is energized, the relief valve external control port through the oil tank, so that the pump can be unloaded.

4. When the external control of the pilot relief valve is connected with the relief valve with lower pressure regulation, the oil pressure in the upper chamber of the main valve core can lift the overflow as long as the adjustment pressure of the low pressure valve is reached, so as to achieve remote pressure regulation. When the solenoid valve is not powered on the right position, the external control port of the pilot relief valve is disconnected from the low pressure regulator, which is equivalent to blocking the external control port. The pilot valve on the main valve regulates the pressure, and the solenoid valve can be used to achieve two-stage pressure regulation, but the setting pressure of the remote pressure regulator must be lower than that of the pilot valve.

5. The relief valve is set on the oil return circuit of the hydraulic cylinder, which can make the stroke back pressure of the oil return chamber of the cylinder to eliminate the forward impulse phenomenon caused by the hydraulic cylinder when the load is suddenly reduced or becomes zero, and improve the smoothness of the moving parts.

Check the relief valve of the hydraulic press, first check whether the regulating spring is damaged, and replace it if damaged; Then check whether the spherical spool or lift head is in its installation position, if there is no spherical spool or lift head in the valve body, if there is a scar, replace it with the appropriate spare parts; Do not ignore the cushion of the valve, whether the device is appropriate or whether there are scars, should be checked regularly; After installing the relief valve, first adjust to the conditioning value, record the number of turns of the relaxed conditioning spring, and then start the hydraulic pump to check the reading of the pressure gauge of the hydraulic press. If the pressure gauge reading is normal, check whether one of the hydraulic cylinders is acting.