Main properties of U Cup seals and sealing principle

U Cup seal has a Y-shaped cross section and is a typical lip-shaped seal. According to the different ratio of the height and width of its cross-section, it can be divided into several categories such as wide, narrow and Yx-type seals. If the height of the two lips is equal, it can be divided into shaft and hole general-purpose Y seal with equal height lip and Y seal for shaft and hole with Y seal, Y seal is widely used in reciprocating sealing device, its service life is higher than O seal. U Cup seal's applicable working pressure is not more than 40MPa, working temperature is -30 ~ +80 ℃. Working speed range: 0.01~0.6m/s when using NBR; 0.05~0.3m/s when using fluorine rubber; 0.01~1m/s when using polyurethane rubber. U Cup seal performance, service life and working pressure limit without retaining ring, are better than polyurethane rubber.

U Cup seal performance characteristics: 1) reliable sealing performance; 2) low friction resistance, smooth movement; 3) good pressure resistance, wide range of applicable pressure; 4) simple structure, low price; 5) easy to install. 

Second, the sealing principle U Cup seal relies on its open lip on the coupling surface of the seal, and a linear contact, the medium pressure under the action of the "peak" contact stress, the higher the pressure, the greater the stress. When the coupling parts are moving relative to each other at working speed, a sealing liquid film is formed between the sealing lip and the sliding coupling surface, thus producing a sealing effect. After the seal lip wears, it has a certain automatic compensation ability due to the medium pressure. Thus, when the shaft extends, the liquid in the "enclosed area" is forced back to the small cavity, thus forming a reliable sealing state and improving the sealing performance of the U Cup seal. The higher the pressure in the "enclosed area", the higher the contact stress of the sub-lip to the coupling surface, and the better the sealing performance.