tailieunhanh - Friction and Lubrication in Mechanical Design Episode 2 Part 6

Tham khảo tài liệu 'friction and lubrication in mechanical design episode 2 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Case Illustrations of Surface Damage 355 force effects of solid rollers cause an additional loading at the outer race contact and a second-order not significant unloading at the inner race contact . Harris and Aaronson 40 made analytical studies of bearings with annual rollers to investigate the load distribution fatigue life and the skidding of rollers. Their work shows that hollow rollers increase the fatigue life of the bearing and decrease the skidding between the cage and roller set. They suggested that attention should be paid however to the bending stress of the rollers and to the bearing clearance. This section describes an experimental study undertaken by Suzuki and Seireg 41 to compare the performance of bearings with uncrowned solid and annular rollers under identical laboratory conditions. Bearing temperature rise and roller wear are investigated in order to demonstrate the advantages of using annual rollers in applications where skidding can be a problem. Test Bearings The two bearings used in the study have the same dimensions and configurations with the exception that one bearing has annular rollers and the other bearing has solid rollers. The details of the bearings are given in Table . Brass is selected as the roller material in order to rapidly demonstrate the effect of annular rollers on temperature rise and roller wear. The ratio of the inside to the outside diameter of the hollow roller is taken as . Three sets of inner rings with different outside diameters are used for each bearing in order to produce the different clearances. Special efforts were undertaken in machining the rollers and rings to approach the dimensional accuracy and surface finish of conventional hardened bearing steels. Test Fixture The experimental arrangement is diagrammatically represented in . the two test bearings a and b one with hollow rollers and another with solid rollers were placed symmetrically near the middle plane of a shaft c . The shaft is .