Corresponding sealing devices are installed on both end faces of rolling bearings. With dust cover and sealing ring, the two properties are different, one is dust-proof and the other is sealing. Sealing is to keep the lubricating grease (oil) inside the bearing from losing in use, and the unclean grease outside is not easy to flow in, so as to ensure that the bearing is in a lubricated state; Dustproof is to protect the dust or harmful gas outside the bearing from entering the bearing cavity to prevent damage to the bearing.

The installation of sealing device for bearing is recent years. In the past, the bearing was open. In order to ensure the lubrication and dust prevention of the bearing, the sealing device was set on the shaft at both ends of the bearing. With the development of industry, especially the popularization of food industry, modern office machinery and household appliances, it is required that the equipment design is compact and the weight is reduced, and the non-contact seal of four rolling bearings should be prevented from water and air leakage, which leads to the bearing with sealing device.

Common ones are rubber or engineering plastic sealing rings, as well as steel plate punching sealing rings (or dust covers). The sealing structure of the sealing ring is diverse, and its sealing effect is also different. If there is a gap between the seal ring and the rotating shaft, it is called non-contact seal. The smaller the gap is, the better the sealing effect is, but the smaller the allowable shaft speed is; On the contrary, the opposite is true. If there is no gap between the seal ring and the rotating shaft, it is called contact seal. The larger the contact area of the contact lip of the seal ring, the better the sealing effect, but the smaller the speed of the allowable shaft, on the contrary, it is vice versa.

1. Rubber sealing ring

How to express the dustproof and sealing of bearing: dustproof is represented by Z and sealing is represented by s (felt ring seal is represented by FS; rubber seal is represented by LS).

2. Dust cover

ZZ: dust cover of retaining ring type steel plate bearing, used for micro bearing, and the stamped metal plate is fixed on the outer ring with spring tightening ring.

2Z: stamping steel plate bearing dust cover, reduce grease leakage, and strengthen the metal plate on the outer ring with stamping processing.

3. Sealing ring

TT: retaining ring type Teflon bearing sealing ring, which is mainly used for micro bearings. The Teflon sealing ring added with glass fiber is fixed on the outer ring with spring tightening ring.

2RS: contact rubber bearing sealing ring, which can effectively prevent the invasion of external foreign matters. The rubber sealing ring is embedded in the outer ring of the bearing, and the sealing ring is in slight contact with the inner ring.

According to the specific use environment of the bearing, the materials used for the dust cover and sealing ring are also different. The following briefly introduces the materials used for several dust covers and sealing rings.

1. Standard bearing dust cover material

The standard material of the dust cover of the bearing is cold-rolled electro tinned steel plate, and sometimes asi-300 stainless steel is used.

2. Rubber sealing ring material

The bearing sealing ring is mainly made of nitrile rubber. For high temperature environment, fluororubber and silicone rubber are also widely used.

① Silicone rubber: MQ / PMQ / VMQ / PVMP, temperature range: - 70 ~ 200 ℃; Hardness: 25 ~ 80; Features: high temperature resistance and dryness, high wear resistance, resistance to sunlight and ozone aging; Limitation: poor surface wear and crack resistance.

② Hydrogenated (nitrile rubber): HNBR / NEM, temperature range: - 35 ~ 165 ℃; Hardness: 50 ~ 90; Features: heat resistance, high ductility and chemical corrosion resistance; Limitation: not suitable for ultra-low temperature conditions, avoid direct sunlight and chemical erosion.

③ Fluororubber: FKM / FPM, temperature range: - 28 ~ 200 ℃; Hardness: 50 ~ 95; Features: high temperature resistance, remarkable chemical corrosion resistance, and corrosion resistance to petroleum products; Limitation: not suitable for low temperature operation.

④ Polypropylene rubber: ACM rubber, temperature range: - 18 ~ 175 ℃; Hardness: 40 ~ 90; Features: strong resistance to hot oil, sunlight and ozone erosion, and strong crack resistance; Limitation: poor waterproof performance, not suitable for ultra-low temperature working state.

Whether the bearing uses dust cover or seal ring is related to the use requirements of the bearing. The dust cover does not contact with the inner ring of the bearing and is installed in a non-contact manner. The sealing ring is in contact with the inner ring of the bearing and is installed in contact. Therefore, the limit speed of the dust cover bearing is higher than that of the seal ring bearing, and the protection grade of the seal ring bearing is higher than that of the dust cover. The waterproof performance of the seal ring bearing is good, and the seal ring bearing can better prevent the outflow of grease.

The sealing of bearings is first of all widely used in a large number of deep groove bearings. In recent years, all kinds of rolling bearings have bearings with different seals. Therefore, sealing is one of the important directions for the development of bearing technology. Different structures of bearings and different working conditions require different structures and materials of sealing rings.