Traditional Cylinder Compression Analyzed by Help of Internal Stripe Patterns
To study material flow of extruded aluminium alloy AA6082 under hot forging
conditions cylinders of same diameter but different heights were compressed between heated
parallel dies. The cylinders contained a special designed marker material pattern of vertical
stripes inside a symmetry plane. After deformation the pattern were revealed and the exact
positions of the marker material lines extending into the boundary interface between cylinder
and die were measured. The stripe pattern as in initial state of cylinder was set up in
simulations using the FEM-code DEFORM. Stripe patterns from simulations and experiments
were compared at different stages of compression. The lubricant was a dry powder lubricant
added to the dies by means of electro-static attraction. By manipulation of friction in
simulation we tried to reproduce the experimental metal flow of the stripe pattern over the
die-workpiece interface. In this way, i.e. by inverse modelling, for the lubricant applied in the
experiments, we were able to deduce important information regarding friction, the main
factor that controls metal flow over the die workpiece interface.
Dirk NOLTE, Henry VALBERG
Metal Forming, Physical Modeling, Internal Grid Pattern, Material Flow, Friction Measurement, Contrast Material.