Ultrasonic micro punching with flexible punch for thin stainless sheet metal

Abstract

In this paper, an effective ultrasonic-assisted micro-punching method for thin stainless sheet metal with molten plastic as flexible punch is adopted. The minimum micro hole and arrays with diameter of 0.3 mm were punched on rolled state thin stainless sheet metal with a thickness of 10 μm. The deformation mechanism and forming parameter quality were investigated. The experimental results show that cylinder pressure, ultrasonic power, and ultrasonic vibration time were the key parameters which affect each other. The ultrasonic vibration time needed to be properly set up according to the preset cylinder pressure and ultrasonic power to form a complete punching hole and avoid defects or cracks of the parts. For the micro hole with a diameter of 0.6 mm punched on a thin stainless sheet metal with a thickness of 30 μm, there are no significant effects on the qualities of the punching fracture surfaces when changing the punching parameters in the range of the cylinder pressure of 0.3–0.5 MPa and the ultrasonic power of 60–90%. In the case of cylinder pressure 0.5 MPa and ultrasonic power 75%, the width of shearing zone is between 10 and 29%, and the surface roughness Ra of the shearing zone is in the range of 0.10–0.20 μm. Our results could throw light on improving the fracture surface quality of micro-punched part obtained by ultrasonic micro punching with flexible punch.