Investigation of the ultrasonic vibration effect in incremental sheet metal forming process

Abstract

The mechanism of incremental sheet metal forming is based on plastic and localized deformation of sheet metal. The sheet metal is formed using a hemispherical-head tool in accordance with the path programmed into the computer numerical control milling machine controller. Experimental and numerical analyses have been performed previously on the application of ultrasonic vibration to various metal forming processes. However, thus far, the effects of ultrasonic vibration on incremental sheet metal forming have not been investigated. This article presents the process of design, analysis, manufacture and testing of a vibrating forming tool for the development of ultrasonic vibration–assisted incremental sheet metal forming. The results obtained from modal analysis and natural frequency measurement of the vibrating tool confirmed the emergence of a longitudinal vibration mode and resonance phenomenon in the forming tool. Then, the effect of ultrasonic vibration on incremental sheet metal forming was studied. The obtained experimental results from the straight groove test on Al 1050-O sheet metals showed that ultrasonic vibration led to decrease in the following parameters as compared with conventional incremental sheet metal forming: applied force on forming tool axis, spring-back and surface roughness of formed sample.