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ISSUE 04-05 / 2001 |
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| Bottle Making | BACK to contents |
Bottle accumulator scales
new heights
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| Synergo's
vertical concept of bottle accumulators helps save space and energy |
One of the few disadvantages of PET bottles is
their lack of stability when empty, which means that they have to be carefully
guided every step of their journey from the blow moulding machine or depalletiser
to the filler. In the case of a modest blow-moulding/filling capacity (say
6,000 to 9,000 bph) a 30 to 60 metre conveyor is not uncommon. As more and
more beverage bottlers blow their own bottles and filling capacities increase
we are seeing conveyors from the blow moulder to the filler of 150 meters
and more.
The “Manhattan” principal
Finding its clients faced with this situation the Dutch plastic bottle handling
specialists, Synergo of Geldermalsen, looked at alternative, more compact
solutions. On the basis that each PET bottle must somehow be individually
guided along its path to the filler Synergo engineers concluded that the best
way to save floor space and energy was to break these long horizontal conveyors
down into handy 3 or 4 metre lengths and stack them vertically – a concept
which led to the development of the Vetrac vertical accumulator.
The first and most obvious advantage of such a concept is the fact that use
can be made of the full height of the bottling hall, and of space that may
otherwise remain empty. It also considerably reduces the physical distance
between the bottle blower and the filling machine, which in turn contributes
to personnel efficiency as well as a compact plant layout. A typical Vetrac
installation sufficient for a 32,000 bph filling line has a footprint of only
4.5 m x 4.0 m and is 4.5 m high. It requires an absolute minimum of conveyor
length from the bottle blower and onward to the filler. The total effective
buffer length provided by such an accumulator is 240 metres - considerably
longer than the minimum air conveyor length normally recommended for this
output level.
Numerous variants
Bottles are fed automatically onto horizontal carrier sections within the
Vetrac accumulator, each of 3 or 4 metres in length and capable of holding
34 or 45 1-litre bottles in a way that avoids any scuffing, or damage to the
shoulder of the bottle. The carriers, once loaded, are moved vertically up
or down depending on the selected infeed position, and the bottles, which
always remain vertical, are presented for outfeed on a “fist-in/first-out”
basis. A basic unit with one bank of 3-metre carriers is capable of buffering
up to 700 1-litre bottles. Accumulators are available with 4 or more banks
of carriers giving effective buffer lengths of 320 metres. Bottles of between
200 ml and 2.2 litres in capacity can be conveniently handled, with rapid
changeover for different neck sizes.
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| Example of various loading and unloading possibilities when using a Vectrac acumulator |
Although the Vetrac operates on the “first-in/first out” principal the bottles
do not necessarily have to follow the full circuit inside the accumulator.
When the blower and filler are working normally bottles take the shortest
route from infeed to outfeed. It is only when the filler stops that the Vetrac
will switch to accumulation mode.
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| Example of various loading and unloading possibilities when using a Vectrac acumulator |
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Each Vetrac unit is custom built, enabling the bottler to select the optimum
combination of infeed and outfeed heights. It is possible, for instance, to
feed bottles in at one floor level and outfeed them to a different floor,
either up or down.
Because the Vetrac accumulator is also capable of handling filled bottles
it can successfully be installed as a buffer between the filler/capper unit
and the labelling machine.
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