“浮动轴承”外圈断裂失效分析

Failure Analysis of Outer Ring Fracture of Floating Bearing

高速线材精轧机主传动增速箱,采用圆柱滚子轴承与深沟球轴承组合的结构作为齿轮轴的支承。由于球轴承外圈不做径向约束,运转中处于浮动状态(浮动轴承),该增速箱使用不到1年,球轴承外圈断裂。经过现场调查、光学显微镜和电子显微镜观察、轴承材料成分和金相组织分析以及轴承外圈有限元仿真等,确定了浮动轴承外圈断裂的直接原因是:浮动状态的外圈应力比固定外圈的应力约大33.3%,造成外圈应力过大;其次,轴承滚道出现严重的剥落和电蚀损伤,引起滚道很大的应力集中,造成外圈的断裂。针对以上问题,提出了改进措施。

The main drive growth box of high speed wire finishing mill adopts the structure of cylindrical roller bearing and deep groove ball bearing as the support of gear shaft.Because the outer ring of the ball bearing is not radial constrained,running in a floating state(floating bearing).The growth box is used for less than one year and the outer ring of the ball bearing is broken.After field investigation,optical microscope and electron microscope observation,bearing material composition and metallographic structure analysis,and bearing outer ring finite element simulation,it can be confirmed that the direct reason for the fracture of floating bearing outer ring is that the stress of floating outer ring is about 33.3%larger than that of fixed outer ring,which results in the excessive stress of the outer ring.Secondly,serious spalling and electric erosion damage occur in the bearing raceway,which causes great stress concentration in the raceway and causes the fracture of the outer ring.Aiming at above problem,the improvement measures are put forward.