Page 59 - 理化检验-物理分册2025年第四期

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质量控制与失效分析 DOI:10.11973/lhjy-wl240024

中速磨煤机磨辊轴螺栓断裂原因

史海燕 ，史晓琦 2
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[ 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 ]
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。
关键词： 磨煤机；螺栓；疲劳断裂；预紧力；显微组织
中图分类号：TG31；TG115.2 文献标志码：B 文章编号：1001-4012(2025)04-0043-04

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

SHI Haiyan , SHI Xiaoqi 2
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[ 1. Inner Mongolia Dengkou Jinniu Coal Power Co., Ltd., Bayannur 015200, China;
2. Inner Mongolia Electric Power Construction（Group）Co., Ltd., Hohhot 010010, China ]
Abstract: 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.
Keywords: coal mill; bolt; fatigue fracture; pre tightening force; microstructure

燃煤电厂磨煤机是锅炉中的重要辅机设备，现 燃烧器进入锅炉炉膛燃烧 [1-2] 。
阶段火电机组每台锅炉均配有若干台中速磨煤机， 某燃煤电厂1号炉B磨煤机1号磨辊轴承温度
为锅炉的正常运行提供煤粉燃料。磨煤机具有煤质 由77.74 ℃持续上升至88.79 ℃，将B磨煤机紧急停
适应性广、研磨件寿命长、电耗低等优点，在现役燃 运。经解体检查发现，1号磨辊支架与磨辊轴连接的
煤机组中应用广泛。机组运行时，原煤通过上方给 3根螺栓中部全部发生断裂。磨辊轴与磨辊支架间
煤机进入磨煤机，经过磨盘与磨辊碾压被研磨成煤 发生约120 mm的相对位移，受位移影响，磨辊轴承
粉。冷、热一次风混合后进入磨煤机，对原煤进行干 失去密封效果，煤粉大量进入磨辊内部，导致磨辊轴
燥，然后一次风将合格的煤粉吹出分离器，煤粉通过 承损坏。
1 号锅炉为 330 MW燃煤机组，每台锅炉配有
5台中速磨煤机。故障磨煤机为MP200B型辊盘式
收稿日期：2024-02-02
磨煤机，该磨煤机具有3个独立固定磨辊的外加力
作者简介：史海燕（1974-） ，男，本科，高级工程师，主要从事火
电厂金属技术监督管理及无损探伤工作，shihaiyan6@163.com 型辊盘式磨机，3个磨辊沿圆周方向120°均匀分布
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