Design of ultrasonic vibration system with vibration mode-conversion for ultrasonic plastics welding

Based on the theory of flexural vibration and coupled vibration,a new hollow cylinder type ultrasonic vibration system with large diameter for ultrasonic plastics welding is designed.This vibration system consists of a transducer,an ultrasonic horn,a plane and a hollow cylinder.The transducer and horn vibrated in longitudinal mode are used to drive a plane vibrated in its second flexural mode.At the same time,while the plane vibrated in its second flexural mode,it is used to drive a hollow cylinder in longitudinal mode vibration.By taking use of the transition between the different vibration mode,the hollow cylinder having large diameter vibrated as a piston in its end surface in higher frequency mode.The experimental results show that the measured resonance frequencies of the system are in good agreement with the computed ones and the system vibrated very well in its longitudinal- flexural-longitudinal vibration mode.The result from this paper will provide assumption for the design of ultrasonic welding system having large diameter when the higher resonance frequency is needed.