Full wedge-type insert mounting method to improve the vibration reproducibility of ultrasonic cutting system

The reproducibility of vibration amplitude during insert mounting plays an important role in the controllability of the ultrasonic cutting process. In this study, a novel full wedge-type insert mounting method was developed to suppress the vibration instability induced by insert remounting. An ordinary threaded connection was selected as a counterpart to evaluate the performance of the proposed full wedge-type method through finite element model (FEM) by simulation and experiments. A theoretical model describing the effects of the connection interface on the vibration characteristics of the ultrasonic cutting system was established accordingly. Both the ordinary and full wedge-type threaded connection methods are shown to have a minimum threshold of screw pre-tightening torque, below which the self-relaxation and vibration disturbance of the cutting insert cause transmission failure of vibration energy and the insert itself. The pre-tightening torque threshold of a full wedge-type threaded connection is smaller than that of an ordinary thread connection. The full wedge-type threaded connection shows much less intense vibration amplitude fluctuations than the ordinary threaded connection during repeated insert mounting operations. These performance improvements can be attributed to contact force amplification effects on the wedge-type interface under the same effective pre-tightening torque under the proposed full wedge-type insert mounting conditions.