Design and Numerical Analysis of Rectangular Sonotrode for Ultrasonic Welding

Abstract

Ultrasonic welding is a fast, clean and high energy process, no flux or filler metal is required, longer tool life and greater efficiency of a weld can be achieved in just a few seconds. Limited length and thickness of weld are the main drawbacks in this process. Welding of large length and thickness materials leads the ultrasonic welding applications unlimited. The design of the components like booster and sonotrode or horn in ultrasonic welding plays a vital role to improve the length and thickness of the welds by generating uniform amplitudes. In the present work, an ultrasonic sonotrode is designed to improve the weld length with suitable uniform amplitudes on the weld bed surface. The design of sonotrode is significantly difficult to obtain the uniform amplitudes at the large weld length. Here, rectangular sonotrode with multiple slots is designed based on theoretical calculations and numerical analysis is performed to obtain the maximum possible weld lengths with uniform amplitudes at a known operating frequency. The finite element method is used to analyze the actual resonating frequency and amplitude distribution of the sonotrode and obtained the maximum weld length as 400 mm for 15 kHz frequency with 3 slots.

HIGHLIGHTS

• One of the major drawbacks in ultrasonic welding is limited length and thickness of weld. Welding of larger length and thickness improves the ultrasonic welding applications.
• Modal and harmonic analysis conducted in order to find the dynamic behaviour of the sonotrode.
• The increase in the weld length of the sonotrode deviates the amplitude distribution within the sonotrode. To overcome this non-uniform amplitude distribution, longitudinal slots are provided in the sonotrode. Also, these slots reduce the weight of the sonotrode.