Performance Characteristics of Metal Bellows Mechanical Seal

The bellows is a sealing element that integrates elastic elements, auxiliary seals and torque transmission mechanisms (ordinary seals do not have this kinetic energy). Its torque mode is unique to bellows mechanical seals. The end surface specific pressure is uniform, and it has the characteristics of high temperature resistance and good tracking performance. The dynamic ring has no auxiliary sealing ring, so one leakage point is reduced, and the friction resistance of the dynamic ring is reduced, and the tracking performance of the dynamic ring is improved.

Commonly used bellows are pressed and welded. Pressed bellows are made by stretching and forming thin-walled tubes on a press or by hydraulic die-casting; welded bellows are made by welding the inner and outer circles of thin film sheets (commonly used).

Compared with pressed bellows, welded bellows have the following advantages:

① Due to the large radial stiffness of the wave node and the variety of manufacturing materials, the range of pressure and temperature of welded bellows is wider;

② Welded bellows can be used as springs with precise working characteristics;

③ Large torsional rigidity;

④ Long fatigue endurance limit;

⑤ Compact size.

Disadvantages of welded bellows: The welds of welded bellows are prone to fatigue damage; when the welded bellows are subjected to hydraulic force, the bellows will produce axial displacement, causing its effective area to change, thereby changing the sealing area ratio.