What are the cylinder sealing structures

Update:22 Apr 2021

The quality of the cylinder seal directly affects the p […]

The quality of the cylinder seal directly affects the performance and service life of the cylinder. The correct design, selection and use of the sealing device is very important to ensure the normal operation of the cylinder. How to extend the service life of the cylinder seal?
The requirements for sealing components are as follows:
(1) Good sealing, abrasion resistance and long service life.
(2) Good stability, not easy to swell and shrink, hard to dissolve, hard to age and soften.
(3) The friction is small.
(4) The surface of the seal is flat and smooth, free of bubbles, impurities, unevenness and other defects. The surface roughness to be sealed has an important influence on the service life of the sealing element, and the surface roughness should be around R=0.4m.
(5) Simple structure and low cost.
The material of the sealing element: oil-resistant rubber, polyurethane, fabric rubber, polyvinyl chloride, gray cast iron or wear-resistant cast iron piston ring and chrome tanned cowhide, etc.
Types of cylinder sealing components:
The shape of the sealing element: 0-shaped sealing ring, Y-shaped, small Y-shaped, L-shaped, J-shaped, U-shaped and V-shaped sealing ring, and metal piston ring. The 0-shaped sealing ring works reliably, has a large static friction factor, and the piston structure is relatively simple. It is currently used in a wide range, but its service life is slightly lower than other types. For dynamic seals, the small Y-shaped seal ring is widely used. Its friction factor is smaller than that of other types. It has a self-compensation function after wear and has a longer service life than others.
The structure and seal of the cylinder piston:
O-ring seal: reliable sealing, simple structure, low friction resistance. After installation, the O-ring seal should be larger or smaller than the inner diameter or outer diameter of the sealing surface by 0.15~0.6mm respectively. If the pre-compression is too large, the friction resistance will be Increase.
L-shaped leather cup and Y-shaped leather cup: reliable sealing, long service life, and greater friction resistance than 0-shaped ring. Generally used for cylinders with a diameter greater than 100mm. During assembly, the screws should not be tightened too tightly to avoid deformation of the cup and damage to the sealing performance.
Y-shaped sealing ring: Reliable sealing, long service life, and greater frictional resistance than o-rings. It is generally used for cylinders with a diameter greater than 100mm to ensure that the compressed air presses the lip of the Y-shaped sealing ring on the surface of the piston.
R&D: For cylinders with a diameter of less than 40mm, the friction resistance is very small, and the annular groove should not be too few.
Small Y-shaped sealing ring: It has high wear resistance and oil resistance, high strength and good elasticity. Its service life is several times longer than that of oil-resistant rubber seals. The friction resistance is much smaller than that of O-shape and Y-shape.
The piston structure is simple, and the aspect ratio of the sealing ring section is greater than 2. The sealing ring will not roll off during use, has good self-sealing performance, and will not leak under low pressure.


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