Leakage is one of the common failures of mechanical equipment. According to the experience of hydraulic cylinder maintenance and repair, combined with theory and practice, the leakage of mechanical equipment hydraulic cylinder mainly includes external leakage and internal leakage.
External leakage refers to the leakage at the hydraulic cylinder barrel and hydraulic cylinder head, cylinder bottom, oil port, exhaust valve, buffer regulating valve, hydraulic cylinder head and piston rod. It is easy to observe directly from the appearance.
Internal leakage refers to the leakage of pressure oil from the high pressure chamber inside the hydraulic cylinder to the low pressure chamber, which occurs at the connection between the piston and the cylinder wall, and the piston and the piston rod. Internal leakage cannot be observed directly. It is necessary to unilaterally enter the pressure oil to stop the piston at a certain position or end point, and observe whether the other oil port leaks outward to determine whether there is internal leakage.
Whether it is external leakage or internal leakage, the main reasons are: poor sealing, poor connection at the joint and other factors. Now, let's talk about the causes of hydraulic cylinder leakage:
(1) The structure and material of the seal
The difference in the structure and material of the seal will directly affect the leakage of the hydraulic cylinder. As the result of the seal has various forms, it should be selected reasonably according to the working pressure of the hydraulic cylinder, the reciprocating speed of the piston rod, and the working temperature of the hydraulic cylinder.
(2) The quality of the contact surface between the sealing groove and the seal
If the seal is installed in a sealing groove with low dimensional accuracy, surface roughness and shape and position tolerance, it may cause damage to the seal and cause leakage.
(3) Damage and failure of seals
During the assembly process of the seal and the contaminated hydraulic oil containing solid particles will damage the seal and cause leakage. In addition, the seals working in a high temperature environment (such as when the door is sealed by a hydraulic gun) will also accelerate the aging of the seals, leading to the failure of the seals and the leakage of the hydraulic cylinder.