热冲压高强钢电阻点焊质量评估系统

针对热冲压高强钢电阻点焊焊后质量的评估问题,基于LabVIEW点焊设备状态监测系统提取点焊过程动态电阻信息,分析了正常焊点、未熔合焊点、飞溅焊点的动态电阻曲线特征,并提出一种五数概括阈值设定方法.结果表明:未熔合焊点与正常焊点的动态电阻曲线在上升阶段的速度、下降幅度、收尾值和有效值等特征指标上有着明显的区别.飞溅焊点的动态电阻曲线发生骤降,对曲线进行最小二乘法拟合与实际曲线相减求取差值曲线,将其均方根值作为飞溅焊点的特征指标.因此,依据焊点评价特征指标,可实现点焊质量的在线评估并取得良好效果.

Quality Evaluation System for Resistance Spot Welding of Hot Stamping High Strength Steel

Aiming at the problem of quality evaluation for resistance spot welding of hot stamping high strength steel, the dynamic resistance information of the normal welding spot, the welding spot with incomplete fusion, and splash welding spots extracted by the LabVIEW system were analyzed. A five-digit generalization method was proposed to set the threshold value. Results show that the dynamic resistance curves of the welding spot with incomplete fusion and the normal welding spot have obvious differences in the characteristic parameters such as the parameters of speed, falling range, ending value and effective value. When the splash welding spot happens, the dynamic resistance curve will drop sharply. The least squares fitting is performed on the dynamic resistance curve of the splash welding spot and the actual dynamic resistance curve and the fitting dynamic resistance curve is subtracted to calculate the root mean square values, namely, splash characteristic index. Therefore, on the basis of characteristic indexes, on-line evaluation of the welding quality is obtained and good results are achieved.