Development of Amplitude Measurement System for Ultrasonic Vibration Assisted Micro Forming

Abstract

Microforming is a process that involves forming a material through plastic deformation at a micro level. However, this method encounters an issue at the micro-scale known as the size effect. There are several new approaches to overcome these difficulties, one of which is using Ultrasonic Vibration Assisted (UVA) micro forming. UVA micro forming is a forming method by applying high-frequency vibrations to the workpiece to reduce forming forces, increase smooth zone, reduce surface roughness, and increase accuracy. A bolted Langevin transducer is needed to produce vibration, which converts electrical signals into acoustic signals in the ultrasonic frequency range. Therefore, the vibration characteristics must be considered in detail to find the best parameters in the micro forming process. This study aims to develop an amplitude measurement system for UVA micro forming. Several things that need to be considered in designing a measurement system are pre-stress characteristics, resonant frequency of the machine, and the amplitude of the vibration generated by the system. Firstly, a pre-stress test was carried out by tightening the pre-stress bolt slowly until the resonant frequency did not change. Then, the resonant frequency is measured using signal generator, oscilloscope, transducer, and resistor to determine the system’s resonant frequency. Finally, the vibration amplitude is measured by observing the displacement at the end of the punch using a digimatic indicator. The result shows that the resonance frequency that produces longitudinal vibration for UVA micro forming system is 28,720 Hz, with a pre-stress of 30 MPa with torque of 14.36 Nm, and total displacement on the normal axis is 9 μm.