Hole Flanging with Multi-action Extrusion

摘要

Flange height and lip thickness are generally restricted by the formation limit of sheet metal blank in conventional hole flanging operation. In this work, "extrusion" is utilized with an aim to obtain a higher flange with even lip thickness, while "multi-action" is incorporated in the die design by holding the cup blank with a stripper subject to counter-pressure. The punch and a movable die then proceed together to avoid buckling on the wall of the cup blank. An FEM software DEFORM is used in simulating the tool design with its 2-D axis-symmetric module. The result shows that hole flanging with multi-action extrusion with its stripper subject to counter-pressure, compressive radial stress increases while compressive axial stress decreases as the workpiece flows towards the flange. Therefore the workpiece tends to dilate instead of forming the flange in forming small flanges. The tool trial-out shows that flanges of larger diameters are easier to extrude and the thickness of the blank bottom increases slightly.