The function of the cylinder piston rod sealing ring, how to install the cylinder piston rod sealing ring

The function of cylinder piston rod sealing ring


The sealing structure and sealing ring for the piston rod are key components in the reciprocating actuator. It is not only related to leakage problems, but also affects the performance and life of the entire machine and equipment. In the reciprocating actuator, the piston rod mainly bears a certain axial force and reciprocates at a certain speed to perform external work. With the development of science, technology and industry, the requirements for reciprocating motion are getting higher and higher. Especially when the cylinder moves at high pressure and high speed, the issue of sealing structure and sealing ring for piston rod becomes particularly important.





In the past, O-shaped sealing rings, narrow-section Y-shaped sealing rings and V-shaped sealing rings were used to seal the cylinder piston rod. These sealing types often cause premature wear of the sealing lip due to dry friction between the piston rod and the seal, resulting in large friction resistance. In the past, O-shaped sealing rings, narrow-section Y-shaped sealing rings and V-shaped sealing rings were mostly used for sealing the piston rod. Commonly used rod sealing structures and sealing rings have relatively low allowable movement speeds, so they are widely used in situations where movement speed is not required, such as hydraulic equipment in engineering machinery, metallurgical equipment, and light industry and agricultural machinery.





Combined sealing rings, such as K-type special seals, are composed of two different components: one is a stepped sealing ring (main seal) made of polytetrafluoroethylene and bronze filler, and the other is an O-shaped sealing ring ( Elastic element and secondary sealing function). The combined sealing ring (k-type special seal) has the characteristics of low friction resistance, no crawling during startup, extremely low leakage and anti-wear. The combined application of cylinder seals avoids contact between metals, improves the support capacity and withstands a certain lateral force, has small friction, and is suitable for high-pressure and high-speed systems, which has been confirmed by tests.





The oil cylinder in hydraulic machinery equipment is composed of a cylinder block, a piston, a piston rod, a cylinder head, and a sealing ring. However, piston sealing refers to the sealing principle between the cylinder and the piston. If the sealing is not good, it will affect the performance of the oil cylinder. The sealing groove is opened on the piston. The cylinder piston rod sealing ring refers to the seal between the piston rod and the cylinder head. If the sealing is not good, oil will leak. The sealing groove is opened in the hole. The sealing groove opened on the shaft should seal the hole, that is to say, it is the piston seal. Therefore, a DSH hole-shaft sealing ring must be used. The sealing groove opened on the hole should be used to seal the rod, that is, the piston. Rod seal, so use a shaft seal.


Piston rod sealing bud type sealing ring
A typical compressor stuffing box consists of a series of sealing rings. Each ring is used to prevent or restrict airflow from entering the atmosphere or isolation chamber. Each set of sealing rings is installed in a separate stuffing box. Each sealing ring is tightly clamped on the piston rod to achieve sealing effect. In addition to the stuffing box that seals the cylinder, there is an oil scraper ring on the piston rod, which prevents oil from escaping from the crankcase along the piston rod.



DSH piston seal
The piston sealing ring is installed on the piston to prevent gas leakage inside the cylinder. As a double-acting sealing ring, its function is to prevent gas from one side of the piston from leaking to the other side. Compared with single-acting cylinder machinery, the piston sealing requirements are higher to prevent gas in the cylinder from leaking into the isolation chamber.



How to install cylinder piston rod sealing ring


1. Use the thumbs of both hands to open the piston ring and install it into the piston (you are always afraid of accidentally overpushing it and breaking it).
2. The piston ring must be placed flat. The piston sealing ring should be pushed into the cylinder first, and then the piston ring should be adjusted and slowly pushed in.
3. Apply engine oil to the piston and cylinder, and then push the piston into the cylinder (this step feels the most difficult. When pushing in, the piston ring will always come out. If you use a little force, it will be broken). Be sure to use engine oil. Lubricate it with special pneumatic lubricating oil, or apply some lubricating oil inside the cylinder itself to the piston ring and sealing ring, and push it into the cylinder.
4. Push the piston part way into the cylinder, and then install the cylinder to the connecting rod.