Common non - contact seal has gap seal, oil - slingshot seal and labyrinth seal and other forms.Due to the existence of clearance, in addition to the oil ring seal, non - contact seal is used for grease lubrication occasions.In order to improve the reliability of seals, various seals can be used in combination.
As a result of the non-contact sealing device of the seal gap, in addition to the presence of lubricant internal friction, will not appear any other friction, therefore, the non-contact sealing will not produce wear, use for a long time will not produce obvious temperature rise, can be applied to the higher speed of the place.But the sealing gap must not be too large, otherwise the sealing effect is very poor.
Non-contact sealing of bearing bearing bearing parts:
1. Clearance seal: simple structure, can meet the general conditions of the sealing requirements.D ≤50mm, e=0.25 ~ 0.40mm;D > 50mm, e=0.25 ~ 0.6mm.
2. Groove seal: the groove is filled with grease to make dust difficult to enter, there are two forms: ring groove and spiral groove.There are generally three ring slots.Groove width b=3 ~ 5mm;Groove depth t=4 ~ 5mm.
3. Labyrinth seal: when the labyrinth curve is filled with grease, the sealing effect is better than the groove seal.Labyrinth seals can be divided into radial and axial two forms.Selection of radial and axial clearance: d≤50mm, a=0.20 ~ 0.30mm, b=1.0 ~ 1.5mm;D =50 ~ 200mm, a=0.30 ~ 0.50mm, b=1.5 ~ 2.0mm.
4. Oblique labyrinth seal: when the shaft deflection is large, the curved inclined plane can swing with the center.A good sealing effect can be achieved by filling grease in the winding of oblique labyrinth seal.
5. Rammed steel labyrinth seal: the composite labyrinth seal composed of rammed steel sheets, the rammed steel sheets can be mounted on the shaft or shell by fitting, without axial fastening, simple structure.If it is filled with grease in the winding path of the rammed steel sheet maze, it has better sealing effect.
6. Oil swing ring seal: when the oil is lubricated, a groove is cut out on the shaft or a ring is installed. The oil that is to be lost outwards can be thrown out radially and returned to the oil pool through the oil collecting chamber and oil hole on the bearing cover.It is also possible to install an oil ring on the bearing, which is often used in combination with the gap seal.