Principle of the Packing

The surface of the axis of the principle of operation of the root is very uneven in the microscopic situation, and the root can only be partially fitting. So there is a tiny gap between the root and the shaft, like a maze. The media is intercepted several times in the maze to achieve sealing.

The filler seal is packed in the filler letter and the filler is pressed against the surface of the shaft by the filler cap. Because the shaft surface is always a bit rough, it and filler can only be partially fit, and part of the contact, this forms numerous mazes. When the pressurized media passes through the shaft surface, the medium is throttled several times, with this "maze effect" to reach the seal. Filler and shaft surface fit, friction, also similar to sliding bearings, solid should have enough liquid to lubricate to ensure that the seal has a certain life, that is, the so-called "bearing effect." It can be seen that a good filler seal, that is, the maze effect and bearing effect of the synthesis.

The compression force of the filler to the shaft is generated by tightening the pressure cap bolts. As the filler is a plastic, when subjected to axial compression, the friction force causes the pressure force to gradually decrease along the axial direction, while the resulting radial pressure force makes the filler close to the axial surface and prevents the outer leakage of the medium. Radial pressure force distribution from the outer end (press cap) to the inner end, first a sharp decline after flattening, the distribution of media pressure gradually from the inner end to the outward end, when the outer media pressure is zero, the leakage is very small, greater than zero leakage.

With the continuous emergence of new materials, the type of filler structure also has a great change, which will undoubtedly promote the application of filler sealing more extensive, as the material used as filler should have the following characteristics: a certain elastic plasticity. When the filler is subjected to axial pressure can produce a large radial pressure force to obtain a seal, when the machine and shaft vibration or shaft has beat and eccentricity, there can be a certain compensation capacity (followed); chemical stability. Neither corroded, dissolved, or contaminated by the medium; The medium has some penetration of most fibers, so the filling tissue is required to be dense, for which filling often needs to be impregnated, filled with a variety of lubricants and fillers; When friction heat can withstand a certain temperature, easy to remove, simple manufacturing, low price.