Mechanical Seal Overview

Mechanical seal (face seal) is a device used to solve the sealing problem between the rotating shaft and the machine body. It is a device that prevents fluid leakage by maintaining the fluid pressure of at least one pair of end faces perpendicular to the axis of rotation, the elastic force (or magnetic force) of the compensation mechanism, and the cooperation of the auxiliary seal to maintain fit and relative sliding to form a device to prevent fluid leakage. It is commonly used in pumps, Rotary fluid machinery such as compressors and reaction stirrers are also used for sealing gear boxes, ship tail shafts, etc. Therefore, the mechanical seal is a universal shaft sealing device.

       There are various mechanical seal structures, and the most commonly used mechanical seal structure is the end seal. The static ring and moving ring of the end face seal form a pair of friction pairs. The function of the friction pairs is to prevent medium leakage. It requires the static ring and the moving ring to have good wear resistance. The moving ring can move flexibly in the axial direction, automatically compensate for the wear of the sealing surface, and make it fit well with the static ring; the static ring has floating properties and plays a buffering role. . For this reason, the sealing surface requires good processing quality to ensure good fitting performance of the sealing pair. The basic components that constitute a mechanical seal include a static ring, a moving ring, a gland, a push ring, a spring, a positioning ring, a shaft sleeve, a moving ring seal, a static ring seal, a shaft sleeve seal, etc.

      Elastic elements (springs, bellows) mainly play the role of pre-tightening, compensation and buffering. They are required to always maintain sufficient elasticity to overcome the friction of auxiliary seals and transmission parts and the inertia of moving rings, etc., to ensure good fit of the end face seal pair. The material must be corrosion-resistant and fatigue-resistant in order to follow the moving ring.

      Auxiliary seals (0-shaped rings, V-shaped rings, U-shaped rings, wedge-shaped rings and special-shaped rings, etc.) mainly serve as seals for the static ring and the moving ring, and also play a floating and buffering role. The sealing elements of the static ring are required to ensure the sealing between the static ring and the gland. The static ring has a certain degree of floating. The sealing elements of the moving ring are required to ensure the sealing between the moving ring and the shaft or sleeve and the sealing of the moving ring. Floatability. Materials require heat resistance, etc.