中速磨煤机磨辊轴螺栓断裂原因  

Reason for bolt fracture of grinding roller shaft in medium speed coal mill

作　　者：史海燕 史晓琦 SHI Haiyan;SHI Xiaoqi(Inner Mongolia Dengkou Jinniu Coal Power Co.,Ltd.,Bayannur 015200,China;Inner Mongolia Electric Power Construction(Group)Co.,Ltd.,Hohhot 010010,China)

机构地区：[1]内蒙古磴口金牛煤电有限公司,巴彦淖尔015200 [2]内蒙古电力建设(集团)有限公司,呼和浩特010010

出　　处：《理化检验(物理分册)》2025年第4期43-46,共4页Physical Testing and Chemical Analysis(Part A:Physical Testing)

摘　　要：某燃煤电厂1号炉B磨煤机1号磨辊轴运行期间,其轴承温度升高,经停运、解体检查,发现磨辊支架与磨辊轴相连的3根螺栓全部断裂。采用宏观观察、金相检验、化学成分分析、扫描电镜分析、硬度测试等方法分析螺栓断裂的原因。结果表明:螺栓沿变截面处螺纹牙底及螺栓头部与螺杆过渡处产生较大应力集中,螺栓螺纹牙底处硬度偏高,心部组织异常,导致螺栓的抗疲劳性能降低;在振动循环载荷的作用下,应力集中处产生微裂纹,螺栓裂纹不断扩展,最终导致螺栓发生疲劳断裂,螺栓预紧力和装配工艺不当也促进了裂纹的萌生和扩展。During the operation of the first grinding roller shaft of the B coal mill in Unit 1 of a certain coal-fired power plant,the bearing temperature increased.After shutdown and disassembly in spection,it was found that all three bolts connecting the grinding roller bracket and the grinding roller shaft were broken.The cause of bolt fracture was analyzed using macroscopic observation,metallographic examination,chemical composition analysis,scanning electron microscopy analysis,hardness testing.The results show that there was a significant stress concentration at the thread root and the transition between the bolt head and the screw along the variable cross-section of the bolt.The hardness at the thread root of the bolt was relatively high,and the core tissue was abnormal,resulted in a decrease in the fatigue resistance of the bolt.Under the action of cyclic vibration loaded,microcracks were generated at the stress concentration point,and bolt cracks continued to propagate,ultimately led to fatigue fracture of the bolt.Improper bolt pre tightening force and assembly process also promoted the initiation and propagation of cracks.

关 键 词：磨煤机 螺栓 疲劳断裂 预紧力 显微组织 

分 类 号：TG31[金属学及工艺—金属压力加工] TG115.2