Composition and classification of mechanical seals Basic components and functions of mechanical seals

Composition and classification of mechanical seals Basic components and functions of mechanical seals

The mechanical seal is a device composed of at least one pair of end faces perpendicular to the axis of rotation, under the action of fluid pressure and the elasticity (or magnetic force) of the compensation mechanism, and cooperates with the auxiliary seal to keep the seal closed and slide relatively. Prevent fluid leakage from each other. The composition of the mechanical seal (1) the main components, including the dynamic ring and the static ring; (2) the auxiliary seal, mainly refers to the sealing ring; (3) the elastic compensation mechanism, mainly including the spring and the push ring; (4) the transmission parts, Receptacles and keys or various screws. The classification of mechanical seals can be divided into two types: rotary type and static type according to whether the spring element is rotating or static; according to the leakage direction of the sealing medium, it can be divided into two types: internal flow and external flow; according to the unloading situation caused by the medium on the end face, It can be divided into two types: balanced type and unbalanced type; according to the position of the static ring, it can be divided into built-in type and external-mounted type; according to the temperature in the sealing cavity, it can be divided into four types: high temperature sealing, medium temperature sealing, normal temperature sealing and low temperature sealing. Class; according to the pressure in the sealing cavity, it can be divided into ultra-high pressure mechanical seal, high pressure mechanical seal, medium pressure mechanical seal and low pressure mechanical seal; according to the number of springs, it can be divided into single spring type and multi-spring type; according to non-contact type The mechanical seal structure can be divided into hydrostatic pressure type, fluid dynamic pressure type and dry gas seal type; according to the division of elastic elements, it can be divided into spring compression type and bellows type. Basic components and functions of mechanical seals (1) The dynamic and static rings keep close contact to form a sealing surface to prevent medium leakage. The dynamic and static rings are required to have good wear resistance. The dynamic ring can move axially to automatically compensate for the wear of the sealing surface, so that it fits well with the static ring. The static ring has a floating property and acts as a buffer. (2) Elastic elements (springs, corrugated plates, serpentine sleeves, etc.) mainly play the role of compensation, preloading and buffering, and are also factors that generate a reasonable specific pressure on the sealing end face. It is required to always maintain elasticity to overcome the friction of auxiliary seals and transmission parts , start the ring compensation effect. The material is required to be corrosion resistant. (3) Auxiliary seals (O-ring, V-ring, wedge-shaped ring and other special-shaped sealing rings) mainly play the role of sealing the static ring and the moving ring, and also play the role of floating and buffering. The auxiliary sealing element of the static ring is required to ensure the sealing between the static ring and the gland, so that the static ring has a certain degree of floating; the auxiliary sealing element of the moving ring ensures the sealing between the moving ring and the shaft or the shaft sleeve. The material is required to be resistant to Heat and cold resistance are close to the medium. (4) Transmission parts The transmission parts include transmission pins, transmission rings, transmission seats, transmission sleeves, transmission keys, transmission lugs or toothed couplings, and their function is to transmit the torque of the shaft to the transmission ring. The material is required to be resistant to corrosion and wear. (5) Fasteners Fasteners include: set screws, spring seats, glands, assembly sleeves, and shaft sleeves. It plays the role of positioning and tightening the static and dynamic rings. It is required to be positioned correctly, to ensure that the sealing surface of the friction pair is in the correct position, and to maintain a well-fitted spring specific pressure; at the same time, it is required to be easy to disassemble, easy to install, and can be reused; the installation of the sealing ring should be paid attention to in cooperation with the auxiliary seal. Angle and pressure elastic amount, pay special attention to the requirements of corrosion resistance and wear resistance at the joint between the dynamic ring seal and the shaft sleeve, and use hard surface cladding if necessary.