Vibration transfer function between horn and anvil measurements in Ultrasonic Metal Welding
Bachelor Thesis of Lu, Shengyu
Ultrasonic Metal Welding (USMW) is a quite important welding technique, because of the relative low heat this welding process generate, it is used in numerous industrial applications. However, this welding technique have a disadvantage, the welding strength have large variance despite the same values of input machine parameters. Thus, to improve this welding technique more knowledge about welding process is required. In this thesis the data sets are 44 measurements on the oscillation of the horn and anvil vibrations along the direction of USMW between two copper layer sheets recorded by Laser Doppler vibrometers (LDV). Based on the model suggested by Balz, this work derives a mechanical model of the welding process, and uses it to estimate the spring and damping coefficients of the weld at different parts of welding. The estimation of the relationship of amplitude and phase shift between horn and work pieces is based on record of high-speed camera filtered at 20kHz. After prepossessing, the 44 measurements are being fitted into mass-spring-damper model using slight window method. Finally, the relationship between frequency and spring-damper coefficient will be analyzed.