Rapid Wrapping Calls For Tight Control
01 November 2004
Daco Engineering Services has supplied the fourth in a series of flow
wrapping machines to Merthyr Tydfil based biscuit and confectionery
manufacturer, OP Chocolate. Employed on a chocolate bar wrapping line,
the new machine is actually a rebuild of an existing, largely
mechanically controlled unit, which takes advantage of the latest motion
control technology to reduce product changeover times and achieve a much
faster throughput. The rebuild involved the installation of a series of
input belts to align the product, plus a variety of optical sensors for
detecting product position, length and height. The servo-driven
horizontal flow wrapping machine uses three Lenze servomotors and drives,
all controlled by a Trio Motion MC216 motion co-ordinator.
The input belts and sensors are linked to three Trio CAN16 input modules
and one analogue module, and all the drives and controls are housed in a
single cabinet, attached to the flow wrapper itself. Two levels of
control (via a touch screen) allow the operator to adjust settings and
change product or, via password, set up 20 individual product programs.
The flow wrapper is able to use the registration input of the Trio motion
co-ordinator to synchronise the whole motor system and ensure accurate
placement of the product on the packaging film, which is fed from a
continuous roll. Film breakages are minimised by synchronising the cross
cutter action precisely to the product conveyor speed, while
automatically making fine adjustments on the fly. Programming support was
provided by Tim Oxtoby of Machinery Control Systems.
When OP decided it needed to double the machine's throughput from the
originally specified 150 bars per minute to 300 bars per minute, it was
found that the MC216 (a 16-axis, 60MHz controller) couldn't cope at the
highest rates because of the sheer volume of sensor signals. The solution
proved very straightforward and involved retrofitting the MC216 with a
Trio MC224 (a 24-axis, 150MHz controller) and transfering all existing
programming parameters via a flash memory stick.
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