Introduction to several common sealing methods of deep groove ball bearings
Users who have used deep groove ball bearings should know that the seals for deep groove ball bearings are usually divided into two types: self-contained seals and external seals.
The built-in seal is mainly a contact seal design. Because the seal is in direct contact with the shaft, friction and severe wear occur during work, so it is only suitable for low speed occasions. The contact seal mainly includes felt ring seal and lip seal ring seal. Felt ring sealing is to form trapezoidal grooves on the deep groove ball bearing cover. The felt is made into a ring or a strip line according to the standard. Felt ring seals are mainly used in grease lubrication. The structure is simple, but the friction coefficient is large. It is only used where the sliding speed is less than 4-5m / s and the operating temperature is not higher than 90 ° C. The lip seal is a lip seal made of oil-resistant rubber in a deep groove ball bearing cover. It is tightly sleeved on the shaft by the elastic force of the bent rubber and the tightening effect of an additional ring coil spring. In order to play a sealing role. The direction of the sealing lip of the lip seal should be toward the sealed part. That is, if the main purpose is to seal the oil, the sealing lip should face the deep groove ball bearing (inward). If the main purpose is to prevent foreign objects from entering, the sealing lip should face away from the deep groove ball bearing. If both requirements are required, it is best to use two lip seals with the sealing lips placed in reverse. Lip seals can be used where the sliding speed of the contact surface is less than 10m / s or less than 15m / s.
The outer seal mainly adopts a combination of labyrinth and contact. The more stages of the labyrinth (not lower than the poles), the smaller the gap and the better the sealing effect. The clearance of the labyrinth is taken from 0.6 to 1.5 mm on one side in the radial direction and 4 to 6 mm in the axial direction according to the size of the deep groove ball bearing. Contact skeleton oil seals are widely used in rolling mills. In order to increase the effect, two or three can be used side by side. The oil seal is directional and cannot be reversed. Hot rolling mills are generally equipped with two oil seals, and the lips of the two oil seals must be outward to the bearing seat to prevent the infiltration of external dirt. Cold strip rolling mills are generally equipped with three oil seals close to one oil seal lip of a deep groove ball bearing inward to prevent grease from overflowing and affecting the quality of the rolled material. Be careful when using the oil seal to avoid damaging the lips when installing the rollers and affect the sealing effect.
RBR type sealing ring, which is a rubber lip type sealing ring for rolling mill bearings, has been widely used in recent years. The RBR sealing ring adopts the axial sealing method. Its lip is attached to the base surface of the gland, which is not affected by the roll bounce. The old grease inside the bearing can overflow, and the external cooling water, scale and impurities are blocked by the lips Enter, there is better sealing effect. Moreover, it is easy to use, and the roll is installed in the bearing seat without any influence during the roll change.