Page 44 - Glass Machinery Plants & Accessories no. 3-2021

COOLING SYSTEMS
OUT hoses, both are equipped
with quick-coupling fixtures which
facilitate set-up and dismantling of
the plunger.
NECESSARY MODIFICATIONS
The plunger gets bored out
(i.e. diameter increase) and fitted
with an insert that very precisely
controls all flow of the coolant
while also being used to potentially
exclude the upper plunger sec-
tion from the cooling effect (the
top drinking glass edge, which is
almost invariably too low in tem- work time and relieving operators
42
42 GMP&A 3/2022
perature). For the interior layout of the mould and only lifted from it
the modified plunger, the cooling once the pressed article has been
medium is supplied through the removed. In some cases, the guide
centre pipe, leaving through the ring is given additional heating
cavity. A recess is used for prevent- between press cycles - a somewhat
ing a drop in temperature by the unproductive procedure rendered
cooling medium in the upper sec- obsolete by the plunger cooling
tion of the plunger. With consider- described above. The guide ring
able experience in the modification now remains on the plunger, its
and conversion of plungers, Famor temperature being constantly
Engineering -as producer of this adjusted to that of the plunger.
system- has already signalled that The free play between plunger
it remains at the disposition of and ring can thus be reduced
customers in terms of making to an unprecedented degree – a
drawings available or undertaking system which results not only in
plunger conversions for an appro- improved product quality as it also
priate charge. prevents seizing of the ring upon
the plunger (due to the difference
ADVANTAGES in temperature between the two
Maintenance of a constant and parts). Here, a saving of the time
controlled temperature will previously required for setting-up
greatly reduce the number of and dismantling the rings remains
rejects attributable to over- or of greatest importance.
under-heated plungers;
There’s no need for constant cool- SUMMARY
ing readjustment, thereby saving The new system offers the fol-
lowing trio of key takeaways:
of a considerable burden; The above-mentioned auto-
Intensive cooling allows for high matic plunger cooling system,
working speeds (cycle times); for automatic glass presses with
The ingenious plunger modifica- only a few stations, semi-auto-
tion (insert) ensures a uniform mated presses and single-station
temperature over the entire exte- presses, yields improved quality
rior surface of the plunger; whilst offering a decreased wall
Precise temperature control allows thickness of the pressed glass
for constant operation which article. This occurs at increased
yields optimum quality (improved operational speed (cycle time).
surface finish, cracking preven- Noise is reduced to an accept-
tion) and, to a certain extent, a able level.
reduction in wall thickness (thus The attention of the press opera-
saving in material) as well as tor is no longer consumed by
improved appearance of drinking constant checking of the plunger
glasses, particularly at the rims. temperature and can instead be
diverted to other, more impor-
FIXING THE GUIDE RING tant activities. O
In automatic presses today, the
guide ring is normally left on the
spring cage – a method that’s
mostly unusable for single sta-
tion presses, given that external
plunger cooling will also cool the FAMOR
guide ring. As a result, this will ENGINEERING SRL
cool to an unacceptable level, espe-
cially because so little heat is trans- Via Avigliana, 3
ferred from the pressed article. 10040 Cottino-Rivalta (TO) - Italy
The guide ring is therefore left on Tel.: +39 011 952629
Renato TROTTA
Sales Director
E-mail: r.trotta@famoreng.com
www.famoreng.com