Metal plastic forming is a universal method widely used in man-
ufacturing industries. As the shapes of parts become more and more
complicated, and the requirements of mechanical properties get
stricter and stricter, there is an increasing demand for new forming
technologies.
Sheet bulk metal forming (SBMF) is one of these new tech-
nologies, which was defined as “forming of sheets with intended
three-dimensional material flow” by Merklein et al. (2012). Wang
et al. (2013) formed bosses on the bottom of a cup by simultane-
ously compressing the cup bottom during deep drawing. Maeno
et al. (2014) applied load pulsation by using a servo press to forge
a stepped stainless steel part. Both Wang and Maeno made their
parts in a single step.
However, for conventional forming of functional shell parts
through SBMF, multi-steps are usually required. Wu and Altan
(2004) studied the flanging and reshaping processes of a clutch
hub and proposed an optimized approach to prevent local crack-
ing. Lin et al. (2007) studied the wall height and thickness variation
in the flanging process, and designed a special mould to obtain
a higher flanged wall. Wang et al. (2008) proposed a sheet metal
stamping-forging process in which a car fly panel part was formed