Numerical analysis of radial extrusion process combined with backward extrusion has
been performed to investigate the forming characteristics of an aluminum alloy in a combined
extrusion process. Various variables such as gap size, die corner radius and frictional conditions are
adopted as design or process parameters for analysis in this paper. The main investigation is focused
on the analysis of forming characteristics of AA 2024 aluminum alloy in terms of material flow into
backward can and radial flange sections. Due to various die geometries and process conditions such
as frictional conditions, the material flow into a can and flange shows different patterns during the
combined extrusion process and its characteristics are well summarized quantitatively in this paper in
terms of forming load, volume ratio etc. Extensive simulation work leads to quantitative relationships
between process conditions and the forming characteristics such as volume ratio of flange to can and
the size of can and flange in terms of the can height extruded backward. It is easily seen from the
simulation results that the volume ratio, which is defined as the ratio of flange volume to can volume,
increases as the gap size and/or die corner radius increase. However, it is interesting to note that the
frictional condition has little influence on the forming load and the deformation patterns. Usually, the
frictional condition is a greatest process variable in normal forging operation. It might be believed
from the simulation results that the frictional conditions are not a major process parameter in case of
combined extrusion processes. It is also found that the can size, which is defined as the height of billet
after forming, turns out to be even smaller than that of initial billet under a certain condition of die
geometry.
Shape Optimization of a Backward Extrusion Process Using a Non-Invasive Form Finding Algorithm
