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Pulse and Volume (Level) Control methods
are supported.
• Advanced design tools: toge<strong>the</strong>r with careful
tests in <strong>the</strong> laboratory, today a verification
and optimization <strong>of</strong> existing installations in
<strong>the</strong> rolling mill is possible. As an example, a
pressure-sensitive film is used to visualize <strong>the</strong>
footprint <strong>of</strong> <strong>the</strong> spraying system. This is mainly
done to identify worn nozzles and to ei<strong>the</strong>r
confirm or optimize spraying angles for best
overlapping.
1.4 Process automation
In cold rolling mills, particularly in foil rolling
mills, best results have been achieved
with powerful closed-loop control systems for
many years. Such systems have been steadily
improved with respect to better measuring
systems (e.g. <strong>the</strong> ‘Optiroll’ flatness measuring
roll), better actuators (e.g. <strong>the</strong> Win-SprayS
rolling oil distribution) and faster control systems.
In that way product quality (e.g. thickness
and flatness) as well as productivity (by
higher rolling speeds) could be maximized.
Fur<strong>the</strong>r optimization is now focused on
meeting <strong>the</strong> high quality requirements already
at <strong>the</strong> strip head. This requires a precise presetting
<strong>of</strong> <strong>the</strong> mill including for example an
optimum bending force to meet <strong>the</strong> flatness
tolerances even before <strong>the</strong> feedback controller
is able to compensate for a wrong flatness.
This requires control methods, which are not
based on measuring <strong>the</strong> parameters to be
controlled. Here process models are necessary,
which are able to approximate <strong>the</strong> rolling
result. For a long time, such future-orientated
physical models were available as <strong>of</strong>f-
line models for rolling mill design and layout.
In recent years, online-model applications
have been developed.
The integrative Optiroll automation system
comprises both, online process models and
model-based functions available throughout
<strong>the</strong> different levels <strong>of</strong> automation hierarchy.
The Roll Speed Compensation (RSC) is
one example for a model-based function that
is integrated in <strong>the</strong> Level 1 control system for
highest dynamic behaviour, as it compensates
for speed-related tribologic effects in cold
rolling. With RSC, much closer thickness tolerances
are achieved compared to <strong>the</strong> classic
closed loop control which is depending on <strong>the</strong>
slow feedback <strong>of</strong> measured thickness. Without
RSC, <strong>the</strong> changing tribologic conditions in <strong>the</strong>
roll gap would result in significant thickness
deviations during acceleration <strong>of</strong> <strong>the</strong> rolling
mill.
Beyond integrated model-based functions
<strong>the</strong> Optiroll automation system provides
trendsetting solutions for dedicated Level 2
process models to comprehensively optimize
<strong>the</strong> rolling process. This is particularly required
for both, presetting <strong>the</strong> closed loop controller
(Level 1) and those controlling parameters,
which cannot be measured during <strong>the</strong> rolling
process. With regard to Level 2 process models,
<strong>the</strong>re are two different approaches:
• Before rolling, roll force and roll stack
deflection are calculated in order to achieve
minimum thickness deviation at <strong>the</strong> strip head
and to reach target pr<strong>of</strong>ile /flatness as quick as
possible in order to avoid scrap material. For
this, <strong>the</strong> calculation <strong>of</strong> <strong>the</strong> roll force on Level
2 provides two options: Tribologic models for
<strong>the</strong> roll gap friction with long-term and shortterm
adaption, as far as cold rolling is concerned.
When it comes to hot rolling, adaption
<strong>of</strong> flow stress strain curves is applied.
ROLLING INDUSTRY
• During rolling, two different types <strong>of</strong> modeling
<strong>the</strong> rolling process are designed:
On <strong>the</strong> one hand, <strong>the</strong> calculation <strong>of</strong> <strong>the</strong>rmal
expansion <strong>of</strong> <strong>the</strong> work roll to correct <strong>the</strong> rolling
force and <strong>the</strong> mechanical bending in order
to avoid pr<strong>of</strong>ile and / or flatness errors and on
<strong>the</strong> o<strong>the</strong>r hand, calculation <strong>of</strong> strip temperatures
in order to keep <strong>the</strong> material properties
in a certain range.
While all o<strong>the</strong>r functions are focusing on
precise pre-setting, <strong>the</strong> <strong>the</strong>rmal models as well
are periodically triggered during rolling, so that
online corrections with respect to pr<strong>of</strong>ile and
flatness or with respect to <strong>the</strong> strip temperature
are possible. Meeting <strong>the</strong> strip temperature
during all passes is not only required for
<strong>the</strong> metallurgical quality <strong>of</strong> hot-rolled aircraft
alloys, but also for <strong>the</strong> exact finishing temperature
<strong>of</strong> cold-rolled can- stock qualities.
For best performance, <strong>the</strong> integration <strong>of</strong>
Level 1 and Level 2 functions is fundamentally
important. Due to <strong>the</strong> modular design, <strong>the</strong>
Optiroll automation system is predestined for
modernizing existing rolling mills. Above that,
especially <strong>the</strong> Level 2 options can be customized
to fulfil <strong>the</strong> individual requirements for
improving <strong>the</strong> rolling mill performance.
2 Resources efficiency
2.1 Electrical power
Electrical power and gas are <strong>the</strong> major forms
<strong>of</strong> energy that are to be considered for <strong>the</strong> efficiency
<strong>of</strong> a rolled-products production plant.
Gas is required for heating processes. For <strong>the</strong>
rolling mill, however, electrical energy is <strong>the</strong>
most important factor.
The first approach to achieve an energy-efficient
rolling mill is <strong>the</strong> identification <strong>of</strong> <strong>the</strong>
major energy consumers. Electrical drives are
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