基于断裂回转支承对连接铸件的影响

The Impact Reasearch of Connection Casting on the Slewing Bearing Fractural

针对目前回转支承开裂问题对连接铸件载荷影响研究较少,阐述了外圈断裂回转支承对连接铸件影响的基本成因,基于断裂力学理论,建立了有裂纹和无裂纹回转支承的有限元分析模型,完成了对外圈开裂后载荷特性分析、裂纹扩展特性分析以及滚动体运动影响分析,获得如下结论：外圈开裂后内圈径向载荷作用将导致开裂两侧螺栓孔位置处切向力发生突变,而径向力保持不变;回转支承开裂对铸件影响主要发生在穿透裂纹形成初期,裂纹源面张开一定间隙后对连接铸件的安全性影响可忽略;外圈裂纹由内向外扩展比由外向内扩展对铸件安全性影响大;开裂后运行回转支承使螺栓孔处位置产生周期放大载荷,降低铸件的使用寿命.对实际工程未及时发现回转支承开裂情况,导致其长时间继续运行,应对连接铸件在开裂位置附近处进行探伤检测.

For few impact research of connection casting on the slewing bearing crack,the fundamental causes were presented for connection casting effect on outer slewing bearing crack. Based on the fracture mechanics theory, the finite element analysis model of slewing bearing with crack and non-crack were established. The analysis of the outer ring crack effect on loading characteristic and crack propagation characteristic and rolling body analysis were completed. The result is obtained as follows. When the outer ring crack,the inner ring radial loading lead to the tangential force with sudden variation in both sides of the bolt hole,the radial force remains the same. Due to the effect slewing bearing crack on casting mainly occurs in the early crack formation,when the source surface crack open a certain gap,the crack effect on casting safety can be ignored. Compared with the outer crack expansion direction from outside to inside,the direction from inside to outside has greatly influence on the safety of castings. when the slewing bearing with crack still work,the cyclic loading in bolt hole located in the near crack is amplified which lead to reduce the life of casting. Therefore if the slewing bearing with crack has run for a long time,the casting location near the crack should be flaw detection.