tailieunhanh - Rolling Bearing Damage 2009 Part 5

Tham khảo tài liệu 'rolling bearing damage 2009 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Evaluation of running features and damage to dismounted bearings Pattern of rolling contact Indentations in raceways and rolling element surfaces On damaged bearing parts indentations are often found in the contact areas which could have the most diverse causes. Since they generally occur evenly distributed in large numbers the indentations originating from the cycling of foreign particles were taken into consideration when assessing tracks section . In the subsequent paragraphs reference is made mainly to those which are locally restricted to the ring. 39 Oblique track in inner ring of deep groove ball bearing 40 Tilted track on a tapered roller bearing Fractures During cycling the material of the raceways and rolling elements is subject to a continuous pulsating stress. This leads to failure patterns like those resulting from the fatigue of mating parts under bending stress fatigue fractures develop. In rolling bearings these fractured areas run largely parallel to the surface and lead to material flaking and are referred to as fatigue damage flaking pittings spalling grey stippiness micro pittings steel pittings etc. 27 I FAG Evaluation of running features and damage to dismounted bearings Pattern of rolling contact Classical fatigue Even with very favourable operating conditions . hydrodynamic separating lubricating film utmost cleanliness and moderate temperatures fatigue damage can develop on rolling bearing parts depending on the stress. Endurance strength is assumed where the index of stress is fs C0 P0 8 C0 static load rating P0 equivalent load . When the stress is greater which means the fs value is smaller fatigue damage can be expected after a more or less long operating period. Such damage due to classical fatigue with cracks starting below the surface seldom occurs. Fatigue damage starts far more often at the surface of the components in rolling contact as a result of inadequate lubrication or cleanliness. The causes are no .