发动机轴承保持架铆钉头脱落原因分析

Analysis of Rivet Heads Shedding off from Bearings Maintainer of Aero-engine

分析了某发动机轴承保持架铆钉头脱落的机理,通过结构、断口、金相分析以及相关零件的尺寸检查,并将现行设计图与外方原设计图进行对比,确定铆钉杆和保持架上的孔配合间隙过大产生的微动磨损是铆钉头脱落的主要原因。铆钉头脱落属于微动疲劳断裂,其断裂与铆钉和钉孔、灯头端面和保持架端面存在间隙,以及钉头转角R处存在折叠及组织变形不良等因素有关。在此基础上,通过将铆钉和钉孔改为过盈配合,并采用双面热铆工艺等改进措施,有效避免了铆钉头脱落故障的发生。提出厂内的控制措施,取得了良好的效果,保证了外场发动机的安全使用。

The mechanism of rivet head shedding-off from bearing maintainer was analyzed. Through structure analysis, fracture observation, microstructure examination and dimension measurement, as well as comparison of the existing production drawing with the foreign original drawing, it was found that the failure mode is fretting fatigue fracture. The rivet head shedding-off was mainly caused by fretting due to the too big clearance between the rivet bars and the matching holes. The fatigue failure of rivets is related to the following aspects： the clearance between rivet bar and hole, the clearance between rivet head and maintainer face, and folding and malformation at the turn angle R. According to the above analysis results, interference fitting-in between rivet and hole was applied, and double-sided hot riveting process was adopted. It was found that these measures can effectively prevent the failure of rivets.