自冲铆机械内锁结构形态的超声无损检测方法  

A Non-destructive Test Method to Evaluate Interlock Structure of Self-piercing Riveted Joints

作　　者：曾凯[1] 田海 邢保英[1] 张洪申[1] 王凯伟 何晓聪[1] ZENG Kai;TIAN Hai;XING Baoying;ZHANG Hongshen;WANG Kaiwei;HE Xiaocong(Yunnan Provincial Key Laboratory of Intelligent Manufacturing Technology for Advanced Equipment,Kunming University of Science and Technology,Kunming 650500)

机构地区：[1]昆明理工大学云南省先进装备智能制造技术重点实验室,昆明650500

出　　处：《机械工程学报》2024年第2期10-16,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(51565022,52065034)。

摘　　要：自冲铆机械内锁区的结构特征直接影响着结构件连接强度和疲劳寿命,是其成形质量评价的重要指标。主要开展自冲铆机械内锁几何特征尺寸及缺陷的无损检测方法研究。基于聚焦超声探头焦平面声压分布,建立结构体边缘声强分布理论公式,并进行试验验证,明确声束扫描结构体边缘时反射回波信号的演变规律,据此提出一种自冲铆钉脚扩张直径的无损检测方法。结果表明:当超声声束靠近钉脚尖边缘时,回波反射声强的变化率呈现先增大再减小的趋势;反映在钉脚扩张底平面上的超声C扫图中时,对应钉脚尖边缘处的灰度-位置曲线的斜率也存在相同的变化趋势,其灰度值变化率的“极值点”可作为钉脚扩张直径测量的边界点。与实际试件剖切测量结果相比较,该检测方法的相对误差为0.14%~1.87%,验证了该方法的可行性。其次,通过分析扩张底平面上的超声C扫图,还可直观地甄别出铆接过程出现的铆接偏心、裂纹等铆接缺陷。The structural morphology in the mechanical interlock of self-piercing riveted joints determines the static strength and fatigue performance of structures,and it is an important evaluation indicator for the joining quality.Based on the characteristics of sound pressure distribution on the rivet focal plane a theoretical formula of the sound intensity distribution in the vicinity of the structure edge is established and a method to measure the rivet expansion diameter is proposed.Both theoretical derivation and experimental results show that the change rate of sound intensity tends to increase and then decrease when the sonic beam of the probe moves to the rivet toe edge,and the grey-scale curves derived from the C scan images near the rivet toe edge demonstrates the same rule.And the“peak”of the change rate of the grey-scale can be used to locate the boundary of the rivet expansion diameter.The measurement results obtained by using this“peak”as the rivet toe edge point have a small error,and the relative error is 0.14%-1.87%compared with the actual profiling results,which verifies the feasibility of the method.And riveting defects:crack and off-center riveting can be judged by using an ultrasonic C-scan image extracted from the expansion plane of the rivet.

关 键 词：自冲铆 机械内锁结构 超声检测 灰度分布 

分 类 号：TB551[理学—物理]