Smoke signals
September 1st 2008 A CC-Link communications systems links inverters
controlling the speed of the key conveyors in a
cigar factory, ensuring quality is not jeopardised
Cigars have a finite shelf life, so
production has to be demand
responsive and be able to respond
effectively to sudden seasonal fluctuations.
Thus the processing plant has to be able
to vary its throughput over a wide range
while maintaining product quality.
The key process in cigar manufacturing
involves breaking down bales of
compacted tobacco then working it up into
expanded tobacco, so that the final cigars
draw smoothly.
The tobacco is then fed as loose
material via conveyors into the
Conditioning Cylinder – this is similar to a
huge washing machine where water and
steam are added
to the tobacco to
make it pliable.
From here the
leaves are
transported via a
vibrating conveyor
belt to loosen
them and are
sucked up by a
vacuum into a
section where the
tobacco's
moisture content
and other
parameters are
checked.
Tobacco which passes this quality
check is then transported by a series of
conveyor bands to a bank of holding silos,
ready for production. When the tobacco is
needed, it is sent to two expanded filler
treatment areas via more conveyor belts.
The expanded filler plant treats the
tobacco to achieve the correct texture for
production.
The tobacco then enters an airlock
where a vacuum is applied to remove
moisture from the leaves. It is screw fed
through the airlock and Pentane gas is
added to make the tobacco leaves expand
to four times their normal size, giving a
much better smoking experience.
After the Pentane is added the tobacco
is packed into boxes of 20kg by a network
of conveyor belts and worm screws and is
sent to the next stage of the complex
tobacco treatment process.
A CC-Link network connects the 20
Inverters that control the conveyors to the
PLC network that forms the plant's control
system. This high-speed fieldbus network
allows the inverters' speeds to be
constantly checked and adjusted to match
the rest of the process speed on a realtime
basis. The CC-Link network also
enables the inverters' alarm functioning to
be monitored, with resetting of any
problems co-ordinated from a central
maintenance SCADA system. More articles from CLPA-Europe: | 
