Detachable expansion fit ultrasonic head with multiple dovetail structures

Abstract

Ultrasonic vibration is a powerful processing tool in cutting and bonding. However, because of its high physical energy, there are few methods to suitably fix an ultrasonic head that contacts a workpiece to an ultrasonic horn, and it is also very difficult to make detachment possible. In preliminary experiments, the loss vibration energy of four different methods including double-sided tape, adhesive material, screw clamping, and expansion fit was compared. It was found that the expansion fit fixing method had the largest friction heat generation, and the amplitude of propagated ultrasonic vibration also increased the most. These phenomena were attributed to the presence of a single dovetail structure in the center of the contact surface between the ultrasonic horn and head, which allowed a gap to form between the ultrasonic horn and head. Therefore, we tried to improve the efficiency of vibration energy transmission from the ultrasonic horn to the ultrasonic head by adding multiple dovetail structures to the contact surfaces to narrow the gap. The multiple dovetail structures suppressed deformation caused by collision of the surface edges and generation of frictional heat. Actually, measured and calculated improvement ratios of vibration at the edge of the ultrasonic head are 51% and 43%, respectively. The temperature transition of the joint measured by infrared thermography and the vibration waveform at the bottom surface of the ultrasonic head determined by a laser Doppler vibrometer experimentally confirmed that multiple dovetail structures improved the vibration energy loss at the contact surface of ultrasonic heads and horns.