Study of the mechanical properties of sheet metals drawn through drawbeads

Abstract

The use of modern materials leads to a need for detailed knowledge of the material flow. Drawbeads are one common way to control serial forming processes. Although they are already well investigated, the effect on the resulting mechanical properties after a drawbead passage is not analysed in detail yet. This work is showing the influence of a drawbead geometry used in deep drawing on typical mechanical properties. Therefore, different sheet metal materials are preloaded in a modified strip drawing test with commonly used drawbeads. In testing, three different levels of pressure between 2.5 MPa and 7.5 MPa and of drawing speed between 10 mm/s and 50 mm/s are combined to nine variations and are examined. Afterwards, specimens are cut out by a laser cutting machine of the drawn strips. Those specimens are then tested with the use of an optical measurement system. Results are discussed in relation to blankholder pressure, drawing velocity and drawbead geometry to work out the main effects. Overall it can be stated, that variations of blank holder pressure and drawbead height lead to significant changes for the material properties. A variation of the drawing velocity in the observed range does not show significant effects.