Drawbeads are commonly used to control material flow during the drawing operation in order to achieve the optimal forming of a part without cracks and wrinkles. Such control is often achieved by using drawbeads in combination with a binder force.
Modifications to the position, length and strength of drawbeads are made during the process design phase to produce an optimal stamped part with minimum material usage. Drawbeads may also be manually modified during the tryout phase in order to obtain the desired process. In general, when using drawbeads, several aspects must be taken into consideration in order to achieve optimal forming conditions:
- Necessary binder force to form drawbeads during binder closing
- Influence of drawbeads on shape of sheet after binder closing
- Force to keep tools closed during the drawing process
- Modification of material properties in area which has passed over a drawbead (additional strains and stresses – in plane and through the thickness, additional work-hardening, additional thinning)
- Modified blank outline
The intensive usage of drawbeads as well as the various modifications necessary require a structured approach to modeling drawbeads in a forming simulation. The modification of such simulation models should be fast and easy and should not significantly influence the computation time. Nevertheless, special attention should be paid to the appropriate implementation of drawbeads as effective drawbead modeling plays an important role in stamping simulation.
Further information on drawbeads at AutoForm: