Friction aided deep drawing of aluminum sheet using blank holder divided into eight segments

A novel process of friction aided deep drawing has been developed by employing divided blank holder. In this process, a conventional circular blank holder is divided into eight segments, each of which can move radially inwards and outwards. When these segments are compressed in the axial direction, the frictional force is generated at the contact surface between a sheet blank and the blank holding segments. These frictional forces contribute to the drawing deformation of a sheet blank on the flange portion. Deep drawn cups can be produced successfully by repeating such operations of loading and unloading. The cup surface also becomes satisfaction compared with the case of four segments. Deep drawing experiments were carried out to improve the surface condition, the shape and dimensions of cups. A supplemental punch is also used to carry a small amount of drawing force and to keep the size and shape of the drawn cup. The experimental resu1ts show that the deep drawing of soft aluminum sheets of 0.5 mm in thickness was produced by repeating this drawing process. A potential of the proposed process was confirmed by successfully producing deep cups 74 mm in height with a drawing ratio of 4.0.