Draft Scheduling vs.
Level 2 model
Draft schedule is one of
the most important
results from the Level 2
model. A high
quality draft schedule
leads to good product
quality while a poor
draft schedule causes
product defects. Level 2
model creates draft
schedule by considering
various constrains.
See details on
Level 2 Draft Scheduling
Issues in the
document
Level 2 Draft Scheduling
Improvement.
Benefits of
Metallurgical Level 2
Model
Traditional
Level 2 model as a
mechanical system cannot
sufficiently meet
today's production
requirements which are
deeply involved in the
metallurgical processes
(controlled rolling,
etc.). Therefore, Level
2 model as a
metallurgical system is
in need. Metal Data consulting
intends to integrate
metallurgical models
into the Level 2 system,
together with the use of
intelligent learning to
compensate for immaturity of
some metallurgical
models in the industry.
Please refer to
Benefits of
metallurgical Level 2
Model for details.
Significance of Accurate
Level 2 Force Prediction
Level 2 model force
prediction accuracy is
one of the most critical
factors for the Level 2
model quality and the quality of the draft
schedule, and thus rolled
steel properties.
Flat rolling
draft scheduling is primarily based on force prediction
together with force related roll deformation (e.g. deflection,
flattening), equipment capacity, etc. Accurate force
prediction is one of the most difficult and significant
problems in Level 2 model. For example, 1% force error
reduction in the strip or plate mill Level 2 model may
have
a economic value of 1 million US dollar per year (see
1% Force Error Reduction
= 1 Million US Dollars
Per Year). Too much force error causes center buckle
and edge wave, etc. of the rolled strip or plate (see
description).
For this reason, Metal
Data consulting would
take Level 2 force model
improvement as the start
point for the Level 2
improvement.
Click to review the
document
Significance of Accurate
Level 2 Force Prediction.
Significance of
Accurate Temperature
Prediction
Sufficient accuracy of
the model prediction,
especially that for the
temperature, makes it
possible for the
scheduled metallurgical
procedure to be actually
achieved. Low accuracy
of the temperature
prediction results in a
poor product quality
(both shape and
properties) and low
yield, because the
actual production is
conducted in a condition
different from the optimal
one from the production
scheduling. For detailed
discussion, please
review
Significance of Accurate
Temperature Prediction.
Level 2 Model
Performance Issues
(Ask
a question)
Current Level
2 systems in the market,
due to the history
reason, primarily use
simple formulas and thus
reach only limited
accuracy. Some systems
are even with design
error in adaptive
learning. Various
issues, if not handled
correctly, would cause
significant error of the
Level 2 model. For the technical
coverage on those issues, please refer
to Metal Data recent
publications. Some
keynotes for those
publications are listed
below as example.
Level 2 Model
Basic Issues
Level 2 Model as a
Metallurgical System
Solution on
Level 2 Model Improvement
(Ask
a question)
Just like a man with
physically strong body has
few occasions in sickness, a Level
2 model with all the
parameters accurately
predicted greatly reduces
chances of strange problems.
If the scheduling algorithms
(in Level 3 production
scheduling and Level 2 draft
scheduling, etc.) are also
optimal, the model operation
should be good.
The concept of Metal Data
model improvement is to give
you an accurate and
well-performed model system
following the steps
described below:
- Improve
Level 2 force
prediction
model, which
is the
weakness of
many systems
- Improve
Level 2
Temperature
Prediction
Model, if it
is also a
source of
problem
- Improve
the roll
deformation
model and
draft
scheduling
system
- Double
check whether
the scheduled
metallurgical
parameters are
the optimal
-
Integrate
metallurgical
models into
the Level 2
system
-
Improve
algorithms of
scheduling
-
And so on.
The actual execution of the Level 2
model improvement, however,
involves extensive
technologies,
because every step described
above requires very high
technical expertise. Metal
Data' strength is exactly in
those areas.
In general, improvement of
the rolling mill Level 2
model utilizes the models as
described in
Rolling mill Level 2 model.
Level 2 Draft Scheduling
Improvement
See new series
Improved Level 2 Draft
Scheduling for Good Plate
Shape and Properties.
Primary purpose for a plate/strip mill Level 2 model is to
create quality draft schedule for good shape and product
properties. Three key issues should be well addressed in a
Level 2 model. Firstly, the logic in creating draft schedule
based on predicted parameters should be effective; secondly,
parameter prediction as basis for the draft scheduling should
be accurate; and thirdly, metallurgical issues such as
retained strain, recrystallization, etc., for model accuracy
and rolled steel properties, should be well considered. On the one hand, a higher draft is
preferred to reduce number of passes and to achieve better
mechanical properties (in view of controlled rolling); on the
other hand, a lower draft is helpful for better shape,
especially in the finish passes.
See
How we Improve your Draft Schedule in the document
Level 2 Model Draft Scheduling Improvement.
Rolling Mill
Force Model Improvement
One of the
primary
parameters the
Level 2 model
takes into
account in
creating draft
schedule is the
roll separating
force. For a
given mill, the
roll separating
force is the one
to determine
whether the
limits of the
mill are reached
(force and
torque, etc.).
Many Level
2 force models use
simple formula and thus
only reach limited
accuracy. Some systems
are even with design
errors in adaptive
learning. Adaptive
learning with
the flow stress
is with certain
limitations and
thus can only
reach limited
accuracy for
force
prediction. By
applying
sophisticated
rolling process
models and
improved
learning logics,
and by
introducing metallurgical
models into
Level 2 system,
we can greatly
increase
Level 2 force
model accuracy
(about 5% error)
and thus
significantly
improve finish
product shape
and rolled steel
properties, and
increase mill
yield and
productivity.
See
Improvement on Level 2
Model Force Prediction
for more detailed
discussion.
Level 2
Temperature
Model
Improvement
We provide accurate model for heat transfer coefficients for every
heat transfer stage. For example, the heat transfer during rolling in the
roll gap depends on roll and stock materials, roll RPM, pressure, descaling
procedure and roll cooling, etc. The heat transfer coefficients in the
inter-pass or during traveling on the run-out table depends on relative speed
between stock and air, etc. We also integrate those models into your
temperature learning procedure.
In addition, our work on
rolling mill
force model improvement
is of great benefit
to the Level
2 temperature model
improvement. See
Improvement on Level 2
Model Force Prediction.
See
Temperature
Model
Improvement
for details.
Integration with
Metallurgical Model
Integration with
metallurgical model can
greatly improve the
quality of the Level 2. Traditional Level
2 model was designed
without metallurgical
concept in mind. Such a
design, however, is
facing ever strong
challenge due to the
application of the new
rolling technologies
such as the low
temperature rolling (in
which the recrystallization cannot
be completed), hold in
the middle of rolling
passes,
and rolling of steels
with microalloys.
For details on Metal
Data Level 2 model
improvement with
metallurgical
integration, please
refer to
Integration of
Metallurgical Model into
Mill Level 2.
Level 2 Model System
Further Development
(Ask
a question)
Level 2 model system
further development can
be categorized in the consulting for Level 2 model
improvement. However,
such an improvement may
require more than
several lines of source
code modification. Due to the
larger scales of the
change, the effect of
improvement is more
significant.
Level 2 System
Architecture Development
Level 2 System
Architecture has been
newly developed and
published recently (AIST08,
MS&T08, etc.). It is
designed with full
metallurgical principles
integrated,
uninterrupted upgrade,
and state-of-the-art
software engineering
technologies.
Related
Level 2 Model
Architecture will
include process models,
metallurgical models,
expert system, system
learning, etc.
Metal Data Level 2 model system
development covers a variety
of areas such as
-
Rolling Mill Level 2 Model
- Reheating
furnace models
-
Accelerated
controlled
cooling (ACC)
model
-
Integration of
metallurgical
model into
Level 2 system
- Prediction
of rolled
steel
properties
(also in Level
3 model)
- Slab size
optimization
and slab grade
optimization
(also in Level
3 model)
For a deep technical
coverage, please refer
to
Level 2 System
Development.
Rolling Mill Level 2
Metallurgical Model
Development
Metallurgical model can be
integrated into the rolling
mill Level 2 model to
increase its accuracy. The
model can solve the problems
of the retained strain,
controlled rolling including
hold, etc. Due to the
complexity of the model
development, intelligent
learning may be used.
Detailed models and model
development are
described in
Rolling mill Level 2 model.