Quantitative detection technology of resistance spot welding based on quasi threedimensional ultrasonic imaging

LI Enxue1, LUO Fuxing2, WU Chengcheng3, YANG Keji3

(1.Tianjin Pipe Group Corporation, Tianjin 300301 China; 2.Hangzhou ZhedaYingyi Electromechanical
Technology Corporation Limited, Hangzhou 311121, China; 3.Institute of Modem
Manufacture Engineering, Zhejiang University, Hangzhou 310027, China)

Abstract: Aiming at the problem of lowcontrast resolution of the conventional ultrasonic Cscan imaging for resistance spot welding quantitative detection, the attenuation characteristics of ultrasonic wave propagation in the tested structure were studied. The characteristics of resistance spot welding ultrasonic signals were analyzed, the attenuation coefficient of ultrasonic signals in the workpiece was measured, and a quasi threedimensional resistance spot welding ultrasound imaging method based on wavelet multisubband difference compensation algorithm was proposed. The frequency and distance attenuation of ultrasonic propagation was compensated simultaneously, the attenuation was reduced and the contrast resolution of resistance spot welding ultrasound image was increased. This method was applied into the study of quantitative detection for resistance spot welding parameters and verified in related experiments. The results indicate that the contrast resolution of resistance spot welding ultrasound imaging is increased effectively, the phenomenon of target object image fusion in background is avoided, and the capability of resistance spot welding parameters quantitative detection and test results characterization are improved.

Key words: resistance spot welds; quality assessment; ultrasonic Cscan imaging; quantitative detection; contrast resolution