Studies on Ultrasonic Welding (Report 2)

Measurements of Vibration Distribution along the Specimens

Abstract

In the case of ultrasonic welding of metal specimens, the vibration direction of welding tip is parallel to specimen surfaces.
The weld strength by ultrasonic welding is directly affected by specimens vibration characteristics.
The purpose of the study is to measure directly the vibration distribution of welding specimens, and to show clearly the effects of specimens vibration and fatigue fracture by vibration on the weld strength.
The automatic vibration amplitude and phase distribution measuring equipment with X-tal cartridge is used. The vibration amplitude and phase distributions are measured with aluminum specimens (thickness=0.5 & 1.0 mm), and welding tip amplitude 0.5, u is used.
The results obtained are as follows;
1) Specimen length has direct affects on the weld strength, when the specimens are at anti-resonance condition of longitudinal vibration and the weldment is a vibration node.
2) The vibration distributions of welding specimens measured are complex and with rather small vibration amplitude, except the case at resonance or anti-resonance condition of longitudinal and bending vibration of specimens with large amplitude.
3) The vibration amplitude of longitudinal and bending mode at welding becomes so large as to cause vibration fatigue fracture of specimens.