- The self-sealing compression type hydraulic seals widely used in hydraulic systems are mainly O-ring seals, circular seals and square seals, etc. They have the advantages of simple structure, easy manufacture and low cost;
- The sealing mechanism of the sealing lip contact area of the seal is of great significance to the sealing function of the seal, which depends on the design of the sealing lip, the structure of the elastic material, and the roughness of the shaft surface. The combined effect of the radial force of the sealing lip, the angle design of the sealing lip and the design of the distance between the lip tip and the center of the spring produces a contact pressure that is asymmetrically distributed to the shaft surface;
- The pressure on the oil side is the largest and increases in steps, and the pressure on the air side decays at a small angle. With the cooperation of the interference, the asymmetric distribution of the contact pressure, and the combined action of the circumferential hoop force generated by the rotating shaft, lead to The structural properties of the sealing lip contact area are deformed.
- The sealing structure is formed when the oil seal is tested for remote rotation, and plays a decisive role in the sealing performance. The influence of the helix and the rotation of the shaft produce a pumping effect on the oil side due to this deformation structure. The friction characteristics of the sliding surface of the sealing lip of the seal are dominated by the viscosity and sliding speed of the fluid, and there is an oil film on this sliding surface. exist.
- The mutual sliding surfaces of the seal and the shaft move in the lubricated state where the oil film is separated, so the friction force is kept small and the wear is small. The flow of oil on the sliding contact surface of the seal is circulated from the atmosphere side, the lubrication of the sliding surface is good, and the progress of wear can be prevented, so there is no leakage.
- Therefore, it is very important to control the two factors of oil seal sealing lip lip material and lip shape so as to affect the lubrication characteristics and sealing principle of the seal.