The lubrication of bearings uses oil films to separate relatively moving rolling surfaces from each other to prevent excessive wear and failure due to rough point contact. If users attach great importance to bearing lubrication technology, they can ensure that stable performance and rotation accuracy can be maintained during the scheduled working life.
As rolling mills are rapidly developing towards high speed, heavy load, high strength, high stiffness and continuous rolling, the requirements for rolling bearings are also getting higher and higher. The bearing seats of hot and cold rolling mills will be invaded by cooling water or other media such as emulsions, which will cause corrosion on the working surface of the bearings. This is quite harmful to the bearings and is also the main cause of bearing wear.
Oil lubrication has a strong cooling effect and can take away dirt and moisture from the bearing. The methods of oil lubrication used for rolling mill bearings include oil mist lubrication, oil-gas lubrication, pressure oil supply lubrication, oil spray lubrication, etc., and oil mist lubrication and oil-gas lubrication are the current mainstream lubrication methods.
Oil-mist lubrication is a relatively advanced form of minimal-quantity lubrication. In metallurgical machinery, it is used for the bearings of various rolling mills, such as backup bearings in strip mills, work-roll and backup-roll bearings in four-high cold rolling mills, and roller guides in high-speed wire rod mills. Oil-mist lubrication provides good lubrication, low oil consumption and effective heat dissipation, and can increase the limiting speed of rolling bearings. Although it represents a major step toward proper lubrication, its application faces various restrictions. In addition, the exhaust gas contains suspended fine oil particles that can seriously pollute the environment and harm human health. It is therefore being phased out and replaced by a more precise, lower-quantity and nonpolluting lubrication method: oil-air lubrication.
Oil-air lubrication sprays dry compressed air with oil mist into the inside of the bearing for lubrication. Because it supplies new oil to the bearing in a timely and continuous manner, it will not cause oil deterioration. The amount of oil used is small, and the cooling effect under the action of air is strong, which can effectively control the temperature rise of the bearing. In addition, the amount of oil or liquid lubricant used in oil-gas lubrication is extremely small and will not cause pollution to the environment.
(Source: Steel Rolling Home)