Rolling bearing is an important mechanical element. Whether the performance of a motor can be fully exerted depends on whether the lubrication of the bearing is appropriate. It can be said that lubrication is a necessary condition to ensure the normal operation of the bearing. It is important for improving the bearing capacity and use of the bearing. Longevity plays an important role. The motor bearing model is generally lubricated with grease, but it is also lubricated with lubricating oil. 1 Lubrication purpose The purpose of bearing lubrication is to form a thin oil film on the surface of the rolling element or between the sliding surfaces to prevent direct metal contact. Lubrication reduces the friction between metals and slows down their wear; the formation of oil film increases the contact area and reduces the contact stress; ensures that the rolling bearing can operate normally for a long time under high-frequency contact stress, prolonging the fatigue life; eliminating frictional heat and reducing Bearing working surface temperature to prevent burns; play the role of dust, rust and corrosion. Oil lubrication is suitable for high-speed bearings and can withstand a certain degree of high temperature, and also plays a role in reducing bearing vibration and noise. Oil lubrication is roughly divided into: 3.3 Splash lubrication Splash lubrication is a commonly used lubrication method for rolling bearings in closed gear transmissions. It uses rotating parts such as gears, oil throwing pans, etc. to splash the lubricating oil. Scatter on the bearing or flow into the pre-designed oil groove along the box wall into the rolling bearing to lubricate the rolling bearing, and the used lubricating oil can be collected in the box for repeated use. Since rolling bearings do not need any auxiliary facilities when using splash lubrication, they are often used in gear transmissions with simple and compact structures. However, the following three points should be paid attention to when using splash lubrication: 1) The lubricating oil surface should not be too high, otherwise the churning oil consumption will be too large, and the oil will be dripped from the oil cup. The orifice drips oil to the bearing to lubricate the bearing. The amount of oil used in the throttle root can be adjusted. The advantages of this lubrication method are: simple structure and easy to use; the disadvantage is: the viscosity is not easy to be too high, otherwise the oil will not drip smoothly, which will affect the lubrication effect. Therefore, it is generally used for low-speed and light-load rolling bearing lubrication. Oil bath lubrication is also called oil immersion lubrication, which is to immerse the bearing part in lubricating oil, so that each rolling element of the bearing can enter the lubricating oil once during operation, and bring the lubricating oil to other working parts of the bearing. Taking into account the stirring loss and temperature rise, in order to slow down the aging speed of the lubricating oil, the general oil bath lubrication is not easy to be used in high-speed bearings. The sediments in the pool, such as wear debris, are brought into the bearing parts, causing abrasive wear. 2) The lubricating oil in the box should always be kept clean, and the magnetic adsorber can be used in the oil pool to remove the wear debris and foreign matter in time to reduce the occurrence of abrasive wear. 3) In the structural design, an oil storage tank and an orifice leading to the bearing can be set on the box wall, so that the bearing is in a state similar to oil bath lubrication or drip oil lubrication, supplementary lubrication, and prevent insufficient oil supply. Oil circulation Lubricating oil circulation lubrication is a way of actively lubricating rolling bearing parts. It uses the oil pump to suck out the lubricating oil from the oil tank, introduce it into the rolling bearing seat through the oil pipe and oil hole, and then return the oil to the oil tank through the oil return port of the bearing seat, and then use it after cooling and filtering. Therefore, this lubrication method can effectively discharge friction heat while removing more heat, so it is suitable for bearing support with large load and high rotation speed. Oil injection lubrication is a type of oil circulating lubrication. However, in order to allow the lubricating oil to fully enter the inner relative moving surface of the high-speed bearing, and at the same time to avoid excessive temperature rise and excessive frictional resistance due to excessive circulating oil supply under high-speed operation conditions, the oil is fed into the bearing seat. A nozzle is added at the port, and the oil supply pressure is increased, and the oil is sprayed onto the bearing by the nozzle to achieve the lubrication and cooling of the bearing. Therefore, oil injection lubrication is a good lubrication method, mainly used for rolling bearings running at high speed, and can be used for occasions where the dmn value of rolling bearings is greater than 2000000mmr/min. The pressure of the oil pump for oil injection lubrication is generally about 3 to 5 bar. In order to overcome and avoid the Coanda effect under high speed conditions, the oil injection speed at the nozzle outlet must reach more than 20% of the linear speed of the rolling bearing. Oil mist lubrication is a kind of minimum quantity lubrication, which uses a small amount of lubricating oil to meet the lubrication requirements of rolling bearings. Oil mist lubrication is to turn lubricating oil into oil mist in the oil mist generator, and lubricate the bearing through the oil mist. Because the oil mist condenses into oil droplets on the working surface of the rolling bearing, the rolling bearing actually maintains a thin oil lubrication state. When the linear velocity of the rolling element of the bearing is high, oil mist lubrication is often used to avoid the increase of the working temperature of the rolling bearing due to the excessive oil supply and the increase of the internal friction of the oil by other lubrication methods. General oil mist pressure is about 0.05 ~ 0.1bar. However, the following two points should be paid attention to when using this lubrication method: 1) The viscosity selection of oil should generally not be higher than 340mm2/s (40℃), because the atomization effect will not be achieved if the viscosity is too high. 2) The lubricated oil mist may partially dissipate with the air and pollute the environment. If necessary, oil and gas separators can be used to collect oil mist, or ventilation devices can be used to remove exhaust gas. Oil-air lubrication uses a piston-type quantitative distributor, which sends a small amount of oil to the compressed air flow in the pipe at regular intervals, forming a continuous flow of oil on the pipe wall and providing it to the bearing. Since new lubricating oil is often fed in, the oil does not age. The compressed air makes it difficult for external impurities to penetrate into the inside of the bearing. The trace supply of oil reduces the pollution to the surrounding environment. Oil-air lubrication is less and more stable than oil-mist lubricating oil, with small friction torque and low temperature rise, especially suitable for high-speed bearings.