In industrial production, machine tools are indispensable and important equipment. In order to ensure the normal operation of the machine tool and extend its service life, the sealing of the bearing is particularly critical. The purpose of this paper is to discuss the sealing form of machine tool bearing and its selection principle, in order to help readers choose the appropriate sealing mode in practical application.
The main function of the bearing seal is to prevent external dust, moisture and other impurities from entering the bearing interior, and to prevent grease or lubricating oil from leaking from the bearing interior. The suitable sealing form can effectively improve the service life of the bearing and ensure the normal operation of the machine tool. In addition, the seal can also play a role in protecting the internal parts of the bearing from the external environment, such as preventing corrosion, oxidation and so on.
Common bearing seal form
Contact seal: The contact seal is sealed by the contact between the seal and the inner and outer ring of the bearing. This sealing form usually includes rubber sealing ring, metal sealing ring and dust cover. The advantage of contact seal is that the sealing effect is good, suitable for high temperature, high speed and other harsh conditions. However, the contact seal may also lead to increased friction, which in turn affects the life of the bearing.
Non-contact seal: Non-contact seal is the use of oil groove, baffle ring, labyrinth and other structures to prevent impurities from entering the bearing interior. The advantage of this sealing form is that it is not easy to produce friction, and it is suitable for low temperature and low speed. However, the sealing effect of non-contact seals is relatively poor and may not be able to completely prevent external impurities from entering the bearing interior.
High temperature environment: In high temperature environment, high temperature and wear resistant seals should be selected, such as metal seals or special rubber seals.
Low temperature environment: In a low temperature environment, seals with good low temperature performance should be selected, such as fluororubber seals.
Wet environment: In a humid environment, seals with good waterproof performance should be selected, such as waterproof rubber seals.
Vacuum environment: In a vacuum environment, seals with good vacuum performance should be selected, such as vacuum metal seals.
High-speed operation: Under high-speed operation conditions, non-contact seals should be preferred to reduce friction and heat generation. If you choose a contact seal, you should pay attention to choosing a seal with a low friction coefficient.
Low-speed operation: Under low-speed operation conditions, contact or non-contact seals can be selected, depending on the cleanliness and lubrication conditions of the external environment.
Lubrication conditions: Good lubrication conditions help to extend the life of the bearing, so the appropriate sealing form should be selected according to the actual lubrication. For example, under the condition of oil lubrication, the oil seal can be selected; Under the condition of grease lubrication, dustproof cover seal can be selected.
Taking the spindle bearing of CNC machine tools as an example, because of its high running speed and relatively harsh working environment, non-contact sealing is usually selected. Specifically, a labyrinth sealing structure can be used to prevent external impurities from entering the bearing through a combination of multiple annular grooves and retainers. In addition, in order to further improve the sealing effect, dust cover or sealing ring and other components can also be added on the basis of the labyrinth seal.
This paper discusses the sealing form of machine tool bearing and its selection principle. In actual work, the appropriate sealing method should be selected according to the specific application scenario and requirements to ensure the normal operation of the bearing and extend its service life. With the continuous development of industrial technology, the requirements for bearing sealing performance will also be higher and higher. Therefore, the research and development of new bearing sealing technology is of great significance.
