Characteristics of two-vibration-system ultrasonic plastic welding with 90 kHz and 20 kHz vibration systems at right angles

The direct welding characteristics of an ultrasonic plastic welding system with an upper 90 kHz longitudinal welding tip with a small vibration amplitude and a lower 20 kHz low frequency torsional vibration welding tip with a large vibration amplitude at right angles are studied. By using a combination of high and low vibration frequency systems with small and large vibration amplitude welding tips, the welding characteristics are improved, resulting in a smaller required vibration amplitude and less damage to the specimens due to vibration than those using conventional systems. The two-vibration-system welding equipment consists of a 90 kHz upper longitudinal vibration source with six bolt-clamped Langevin-type piezoelectric ceramic (lead-zircon-titanate; PZT) transducers 15 mm in diameter, a 20 kHz torsional vibration system 40 mm in diameter and a welding frame. The total required velocity amplitude of the two-vibration-system welding equipment is decreased and the welding characteristics are improved significantly compared to those of conventional one-vibration-system for both soft and hard plastic sheet welding.