The key to supporting the normal operation of the electric spindle is lubrication, so lubricating the electric spindle bearings is an indispensable part of normal machine maintenance. The following will introduce itSynchronous electric spindleSeveral lubrication methods.

The common lubrication methods for synchronous electric spindles include grease lubrication, oil mist lubrication, oil air lubrication, jet lubrication, and under ring lubrication.

Lubricating with grease does not require any equipment and is a commonly used lubrication method for low-speed electric spindles. Spindles with DN values above 1.0 × 106 are often lubricated with oil.

Oil mist lubrication is the process of atomizing lubricating oil into pressurized air to lubricate bearings. This method is easy to implement, the equipment is simple, and the oil mist can both lubricate and cool the bearings. However, the oil mist is not easy to recover, causing serious environmental pollution. Therefore, it has gradually been replaced by a new type of oil air lubrication method.

Oil air lubrication refers to compressed air regularly and quantitatively bringing a small amount of lubricating oil along the wall of a dedicated oil air pipeline to the lubrication area of synchronous electric spindle bearings without atomization. Lubricating oil plays a lubricating role, while compressed air promotes the movement of lubricating oil and cools bearings. Oil and gas are always in a separated state, which is beneficial for the recovery of lubricating oil but does not pollute the environment. When implementing oil air lubrication, it is generally required that each bearing has a separate oil air nozzle, and there are strict requirements for the position of the bearing spray. Otherwise, it is not easy to ensure the lubrication performance, and the oil air lubrication performance is also affected by the compressed air flow rate and oil air pressure. Increasing air flow can improve cooling performance, while increasing oil and air pressure can not only improve cooling performance, but also help lubricating oil reach the lubrication area. Therefore, increasing the oil and gas pressure helps to increase the rotational speed of the bearing. Experiments have shown that increasing the pressure ratio and using conventional pressure for oil air lubrication can increase the bearing speed by 20%.

Jet lubrication is the direct use of high-pressure lubricating oil to lubricate and cool synchronous electric spindle bearings, which consumes a large amount of power and is costly. It is commonly used for ultra high speed spindles with DN values of 2.5 × 106 or higher.

Under ring lubrication is an improved lubrication method, which is divided into under ring oil lubrication and under ring oil air lubrication. Implement oil or oil air lubrication under the ring, where lubricating oil or oil air is sprayed into the lubrication area from the inner ring of the bearing. Under the action of centrifugal force, the lubricating oil is more likely to reach the lubrication area of the bearing. Therefore, it has better performance than ordinary jet lubrication and oil air lubrication, and can further improve the bearing speed. For example, with ordinary oil air lubrication, the dn value of angular contact ceramic ball bearings is about 2.0 × 106. Increasing the oil air pressure can increase the dn value to 2.2 × 106, while using oil air lubrication under the ring can achieve 2.5 × 106.