• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.06a
• /
• pp.99-102
• /
• 2006

In the present study, the blow forming characteristics of AZ31 sheet was investigated to test the feasibility of the practical application of wrought Mg alloys. Mg alloys have drawn a huge attention in the field of transportation and consumer electronics industries since it is the lightest alloy which could be industrially applicable. Most Mg alloy components have been fabricated by casting method. However, there have been a lot of research activities on the wrought alloys and their plastic forming process recently. Shallow cups for the small electronics cases have been stamped with warm die system. However, some technical issues will challenge Mg forming when large parts are considered with warm die system over $200^{\circ}C$. Most of all, thermal expansion of die system will deteriorate a die accuracy. On the other hand, blow forming does not have a problem with inaccuracy with die system. In this study, tensile tests were followed by blow forming at various temperature and pressure. AZ31 sheet showed a superplastic deformation behavior with extensive grain boundary sliding at the temperature above $300^{\circ}C$. However, the deformation behavior was likely to differ depending on stress condition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1994.10a
• /
• pp.55-63
• /
• 1994

The analysis of superplastic sheet forming process is studied by the use of the finite element method using a convected coordinate system and a skew boundary condition. In the formulation, the large inelastic behavior of the superplastic material is described as incompressible, nonlinear, viscous flow. The formulation is then approximated to the finite dimensional space with the use of membrane elements, which results in algebraic linear equations. In addition to the finite element formulation, a pressure cycle control algorithm is combined in the analysis for optimization of the forming time, which deals with the maximization of the strain rate sensitivity, the protection of the thickness reduction, the consistency of the desired strain rate and improvement of formability.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.2
• /
• pp.440-449
• /
• 1996

Superplastic punch forming of sheets is simulated by a finite element method to obtain the optimal punch speed and the related deformed shapes. The punch forming has an advantage of guaranteeing the desired accuracy inside a product and controlling the thichness of a deformed sheet more accurately than blow forming. The finit element code developed is associated with the contact algorithm and the control algorithm of punch speed for the optimum forming. The simulation demonstrates that the variation of the thichness in a blank sheet affects the punch speed and the final distribution of the thichness in a product. The analysis proposes that a ring-typed thichness controller is very effective in controlling the thichness of a deformed sheet appropriately.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.187-188
• /
• 2008