Prediction of dynamic behavior of workpieces in ultrasonic plastic welding

摘要

Ultrasonic plastic welding is a technique for joining thermoplastic parts through the use of frictional heat and deformation heat generated at the interface between the workpiece parts by high frequency mechanical vibration. This paper proposes a method for predicting the dynamic behavior of the contact surfaces of the parts at the beginning of the welding. The method is based on finite element dynamic contact analysis. To validate the proposed method, the predictions of dynamic behavior are compared with the measured data and a proper friction coefficient of the interface between the parts is determined. In addition, the dynamic behavior of the contact surfaces are investigated when the horn is vibrated at two different operating frequencies, 15 and 19 kHz. The results show that the dynamic behavior considerably depends on a friction coefficient. Furthermore, the displacements and elastic strains of the contact surfaces at 15 kHz are larger than those at 19 kHz. This seemingly results in the better quality of weld for 15 kHz operating frequency.