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Topic Summary of the Dissertation
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10. The directly calculated parameters are rolling force, rolling torque,
elastic and plastic strain, elastic and plastic strain rate, plastic work, shape
of deformation zone, stress and temperature distribution, as well as the
workpiece geometry during and after rolling. The also calculated partial
upsetting, partial spread and partial elongation were fed as input into the MARC
main program through a user subroutine. A graphical presentation and evaluation
of the analyzed parameter fields followed with the pre- and postprocessor
MENTAT. The calculated rolling force and rolling torques could be read directly
in the out-file. The shape of the deformation zone could be determined either in
agreement with the tendency of the strain rate in the direction of reduction or
according to the working zone of the external force upon the workpiece nodes. It
is also possible to obtain the deformation of the front and rear ends as well as
the residual stress distributions of the rolled product.
11. After studies of the relative movement of the workpiece and rolls, a
special upsetting model for shape rolling simulation was developed through a
functional combination of the slab method and the FEM. The workpiece was
represented as a three dimensional slab element pair. Each slab element was then
divided into a number of FEM elements (36 elements for the first pass of the
angle steel rolling, for example). The upper or lower roll was defined through
input of the groove cross section and their rotation expansion around the
corresponding roll axes for 3 - 5°
(relating to the length of the slab elements). The slab method is for the
determination of the elongation of the workpiece and the relative velocities
between workpiece and rolls in rolling direction, while the FEM is for the
calculation of other parameters. The distribution of the elongation along the
arc of contact has an important influence on the accuracy of the simulation. The
backward and forward slip don't play a great role. With this model, all
parameters over and above the cross section, such as strain, stress, temperature
and strain rate, as well as spreading and reduction can be calculated. The
parameter distribution over the length of the deformation zone can also be
obtained in accordance with the parameter course over the upsetting time. With
this simplified model, the simulation of an angle rolling pass was performed in
only 5 to 10 minutes with sufficient accuracy.
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