An analytical approach to prediction of internal defects during the flat rolling process of strain-hardening materials

In this paper, the upper bound method has been used in analysis of the flat rolling process
and prediction of internal defects for a strain-hardening material. The arc of contact has been
replaced by a chord. The inlet shear boundary of the deformation zone has been assumed
as an exponential curve and the boundary at the exit has been assumed as a cylindrical
surface. A kinematically admissible velocity field has been proposed and internal, shear and
frictional power terms have been derived. By minimizing the total power with respect to
the neutral point position and the shape of the inlet shear boundary, the rolling torque has
been determined. A criterion has been presented to predict the occurrence of the internal
defects for given rolling conditions. Comparison of the analytically developed approach for
rolling torque and internal defects with published theoretical and experimental data shows
generally good agreement.