Aluminum alloy split bearing isolator

Client: Ansteel Group

Application: bearing seat of dedusting fan

Original seal: labyrinth seal

Working condition: high speed, large shaft displacement during startup, circulating oil lubrication, heavy dust pollution.

Transformation plan: aluminum alloy material, split design bearing isolator, driving and static ring limit bolts.

Reconstruction time: 2015

Transformation effect: no leakage, no pollution in oil tank, stable operation.

Framework oil seal or labyrinth seal (metallurgy, paper mill roll, fan, pump, etc.) are commonly used for bearing seat sealing, and lubricating oil leakage often occurs, and gradually increases with equipment operation. The lubricating oil leakage of the bearing box has affected the stable operation of the equipment, and the production operators need to add lubricating oil regularly to maintain the normal oil level and pressure of the lubricating oil circuit The problem of oil leakage at the shaft seal of large rotating shaft equipment is widespread, especially for large diameter fans. Since some fans were put into use, the problem of leakage has been serious and has not been effectively solved, which not only causes economic waste but also pollutes the environment and seriously threatens the safety of normal production, and has become an urgent scientific research topic.

Many fan bearing boxes are sealed with radial straight labyrinth tooth seals made of aluminum alloy. According to the analysis, the cause of oil leakage is the normal wear of the seal caused by the fan operation. After the fan is operated and disassembled for a long time, the seal deformation and the increase of the clearance between the seal and the rotor result in poor sealing and oil leakage. In fact, due to the long-term operation of the fan, long-term high-temperature environment and grease erosion, as well as a certain manufacturing error in the shaft diameter between the repaired and replaced rotors, corrosion or friction loss occurred on the top of the sealing teeth, resulting in an increase in the gap between the top of the sealing teeth and the shaft surface, a decrease in the closure effect of the seal, and eventually led to oil leakage.

The compound labyrinth seal (bearing isolator) is adopted to replace the straight labyrinth seal. The moving and stationary rings of the bearing isolator are also installed on the end cover with flanges. The moving ring is held on the shaft by two fluororubber O-rings and rotates with the shaft. The dynamic and static rings together form a composite labyrinth design. The dynamic and static rings are made of high-quality aluminum alloy, and the dynamic ring drive ring is made of fluorine rubber. The lubricating oil thrown by the bearing enters the oil return groove along the clearance between the shaft and the stationary ring, and returns to the bearing chamber through the oil return hole in the inward direction under the action of gravity. A small amount of oil droplets formed by cooling oil stars and oil mist enter the oil return groove of the passage and are collected, and return to the bearing chamber through the downward oil return hole under the action of gravity. The outside water and dust enter the dust proof labyrinth chamber along the gap between the static ring and the moving ring, and are discharged through the downward drain hole under the action of gravity and centrifugal force. The dynamic and static rings have no continuous contact when the equipment is running, so there is no wear and heat, nor will it cause temperature rise. Compared with the original straight through seal design, it can effectively prevent leakage, and has dust-proof and waterproof effects. The contact surface between the stationary ring and the shaft is equipped with two PTFE sealing rings, and the PTFE coaxial adopts linear contact to avoid coaxial contact between the stationary ring and the shaft during the equipment opening process, and strengthen the effect of oil mist sealing. There are positioning bolts between the dynamic and static rings to prevent the dynamic and static rings from separating in case of large displacement of the equipment.