Marko Škunca

Coining as a microforming process

Although elastic springback makes a great challenge in sheet metal forming, it is also a value that is considered in the area of coining. It is a parameter that can often make many difficulties when coin should obtain the etching of the die. That can happen because of small coin height in which leading part takes material composition, its grain size and microstructure. It classifies coining process to a group of microforming processes. Therefore, an experiment has been carried out whose task was to provide data about percentage of elastic springback in total deformation during coining process of Al 99.5%. This has been carried out for three different grain sizes of the same material. An experiment has also included microscopic observation of gravure filling for mentioned grain sizes and also for different tool forces. The final result is a correlation between grain size and elastic springback in coining process, and also a correlation between grain size and gravure filling for different tool forces.

Analytic Model For Estimation Of Cold Bulk Metal Forming Simulations

Numerical simulation of bulk metal forming plays an important role in predicting a key parameters in cold forging. Comparison of numerical and experimental data is of great importance, but there is always a need of more universal analytical tools. Therefore, many papers besides experiment and simulation of a particular bulk metal forming technology, include an analytic model. In this paper an analytical model for evaluation of commercially available simulation program packages is proposed. Based on elementary theory of plasticity, being only geometry dependent, model represents a good analytical reference to estimate given modeling preferences like; element types, solver, remeshing influence and many others. Obtained, geometry dependent, stress fields compared with numerical data give a clear picture of numerical possibilities and limitations of particular modeling program package.