Experimental Studies On The Hihg-speed Rolling Bearing With Oil-air Lubrication

This project focuses on the experimental study of high-speed bearing performance under oil-air lubrication.Development of modern industry has necessitated higher running speed of rolling bearings. Lubrication is a key factor that determines the limiting speed of bearings. For ultra-high speeds, the traditional lubrication technique can not help the bearings work well. Alternatively, oil-air lubrication method, due to its high efficiency, dirt ingress preventing as well as environment-friendly, become an optimal choice for ultra-high speed spindle and metallurgical equipment.An old bearing test apparatus was renewed in such way that high-speed bearings with oil-air lubrication could be assessed in terms of temperature rise and vibration. This system can be used to get the relation between the bearing operating performance and oil-air parameters. By checking the damaged bearings supplied by Qingdao Iron and Steel Group Co., LTD., the causations of bearing failure were found and simulation experiments were conducted. Considering the limitation of the hole-type nozzle, a novel nozzle was designed and its advantages are validated by different test methods. The main work carried out includes: 1. Development of high-speed bearing test system with oil-air supplyingAn old bearing test apparatus was rebuilt, and the updated one is capable of assessing the bearing performance under oil-air supplying conditions. The lubrication conditions of the bearing can be evaluated in terms of the outer ring temperature rise. The system features that the axial load and radial load can be applied respectively and the oil feeding parameters such as oil supplying interval, air pressure and air supplying position can be readily adjusted. 2. Experimental study on the relation between oil supplying parameters and bearingperformanceUsing this test system, a series of experiments are carried out under different oil supplying parameters. Some factors dominating the bearing lubrication are revealed. Taking the outer ring temperature as a reference, the variations of temperature with oil supplying quantity, air pressure, as well as bearing speed are investigated, based on which an optimal oil supplying quantity can be obtained. 3. Studies on the bearing failure under oil-air lubrication conditionsBy off-line checking the broken bearing of rolling guides in high-speed wire mills, it is found that the bearing failure is caused by ingress of external dirty particles. An improvement plan is proposed to prevent the particle invasion. Model tests were carried out by mixing particles with lubricants. The wear of test bearings was observed under oil-air supplying conditions. 4. Design of a novel target-type nozzleTo overcome the limitation of the traditional hole-type nozzle, a novel target-type nozzle is developed. On the basis of the original nozzle, guide threads capable of controlling the air/oil flow orientations is mounted. By using this new nozzle, it shows that the oil injection area is reduced significantly and oil supplying efficiency and uniformity are obviously enhanced. The advantages of this new type nozzle are demonstrated by tests under different conditions.