STEEL + TECHNOLOGY 04/2019 EXTRACT

STEEL TECHNOLOGY | 69
Figure 2. Flattener for the 3rd generation grades (Picture: Fives)
issue that was considered to be solved
long time ago: introduction of the flat strip
at the entry shear. Our study for mechanical
equipment to produce the 3rd generation
grade shows that a threading flattener
needs specific design as shown in figure
2 to support additional constrain to
straighten the strip. To avoid roll deformation,
stiffeners are to be installed to succeed
proper threading.
Bending and tension control
Strip mechanical properties impact strip
transportation design not only regarding
tension requirements for a skin-pass mill
and a tension leveller, but also roll angle
losses, as well as energy consumption for
strip bending with consequences on bridle
configuration, strip guiding and electrical
consumption. In order to meet the requirements
of new steel grade production,
Fives developed DMS OptiLine, a precise
software tool, which simulates the
complete running of a strip processing line.
It calculates the requested characteristics
of each motor of the line based on the tension
map request and mechanical properties
received from upstream facilities and
targeted at line exit. It guarantees the
required line tension during operation at
the constant speed, as well as during line
acceleration and deceleration. Accumulators
are also checked according to the real
product mix of the line.
The DMS OptiLine is designed to
achieve the best possible performance by
anticipating every operating scenario and
offering appropriate responses:
• anticipate quality risk linked with strip
driving to prepare development of new
grades or new strip dimensions,
• optimize need of change (motor, bridle,
pinch roll) during a revamping project.
The production is simulated as shown in
figure 3 with a line speed variation, strip
dimension changes and a grade transition
phase. This insight can significantly reduce
the time taken for commissioning.
Skin-pass and levelling
Steelmakers’ needs concerning skin-pass
and levelling equipment remain the same
for the advanced high strength steels:
erase yield point elongation, adjust yield
strength and apply roughness on the strip.
Taking into account the grade range
increase, we must be able to install a skinpass
mill with flexibility to cover yield
strength from 100 MPa to 1,700 MPa (figure
4). For this, rolling and bending forces,
stand and roll dimensions have been
Figure 3. DMS OptiLine modelling results (Picture: Fives)
STEEL + TECHNOLOGY 1 (2019) No. 4