==Abstract==

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Ultrasonic vibration has been applied to many machining processes. It has been reported that the application of ultrasonic vibration to machining has improved machining efficiency and accuracy. In this report, ultrasonic vibration is applied to welding, drilling, and knurling, and its effects are shown through experiments and analyses. In welding, it is shown that ultrasonic vibration can reduce tensile residual stress. In addition, the simulation method using a simple model showed that residual stress is reduced by the plastic deformation caused by ultrasonic vibration. In the drilling process, it was found that the surface roughness of the machined surface was improved when ultrasonic vibration was used. The conditions under which the surface roughness is improved by the impulse due to cutting resistance were also determined. In knurling, it was found that the pressing and friction forces were reduced by the use of ultrasonic vibration. It was also shown that the reduction in pressing force is expressed as the product of the equivalent mass and the amplitude of ultrasonic vibration

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