摘要
针对全扭矩工况(螺栓预紧力矩均为设计值)、欠扭矩工况(螺栓预紧力矩均为设计值的20%)和部分欠扭矩工况(其中一组对角螺栓预紧力矩为设计值,另一组对角螺栓预紧力矩为设计值的20%),系统开展了轴向振动载荷作用下切槽式螺母的防松性能研究;全扭矩工况下研究了切槽处裂纹对切槽式螺母防松性能的影响,利用体式显微镜(OM)和扫描电子显微镜(SEM)等微观分析设备分析裂纹的扩展情况。结果表明:在三种预紧工况下,全扭矩时螺母具有良好的防松性能,但在欠扭矩和部分欠扭矩工况下螺母的防松性能降低,且后者更为严重;螺栓的松动过程可分为两个阶段:第一阶段是螺栓轴向力快速下降,原因是材料发生塑性变形和螺纹接触面应力重新分布;第二阶段是螺栓残余预紧力缓慢下降,原因是螺纹接触面发生微动磨损。此外,切槽处裂纹会降低螺母防松性能,通过微观分析表明裂纹试验后出现明显扩展。
Under three different tightening conditions(C1:the tightening torques of all slotted nuts are equal to the design value;C2:the tightening torques of all slotted nuts are 20%of the design value;C3:the tightening torques of two slotted nuts in the diagonal direction are 20%of design value,and those of two slotted nuts in the other diagonal direction are equal to the design value),the anti-loosening performance of slotted nuts excited by axial vibration were studied.The effect of the crack at groove on the anti-loosening performance of slotted nuts was investigated.The crack propagation was observed with optical microscope(OM)and scanning electron microscope(SEM).The results showed that slotted nuts had significant anti-loosening performance under C1,while the anti-loosening performance reduced under C2 and C3,especially C3.The self-loosening process could be divided into two stages:due to the cyclic plastic deformation and the stress redistribution between the threads,the clamping force decreased quickly in the first stage;due to the fretting wear between the contact surfaces,the clamping force decreased slowly in the second stage.Furthermore,the anti-loosening performance of the slotted nuts with cracks at groove was lower than that of the slotted nuts with no cracks,and the crack at groove expanded obviously after the vibration tests.
作者
孙光阳
何岩
朱喆
胡华民
刘建华
SUN Guangyang;HE Yan;ZHU Zhe;HU Huamin;LIU Jianhua(CRRC Changchun Railway Vehicles Co.,Ltd.,Changchun 130062,China;Tribology Research Institute,Southwest Jiaotong University,Chengdu 610031,China)
出处
《机械》
2020年第9期33-39,共7页
Machinery
基金
国家自然科学基金青年基金项目(51705434)
四川省重点研发项目(2019YFG0290)。
关键词
切槽式螺母
轴向振动
松动行为
裂纹扩展
slotted nut
axial vibration
self-loosening
crack propagation
