Process and apparatus for making hollow glassware

In the manufacture of hollow glass articles such as bottles, a gob of molten glass is blown or pressed into a parison in a premold, the parison being then transferred to a final mold where it is allowed to reside for a period sufficient to equalize its temperature before being blown into its ultimate shape. During the latter step, another final mold receives a parison meanwhile formed in the same premold. The two (or more) final molds associated with a given premold are mounted on a turntable for juxtaposition with the premold preparatorily to each transfer step.

FIELD OF THE INVENTION 
Our present invention relates to the manufacture of bottles and other 
hollow glassware by a two-stage blow-molding process. 
BACKGROUND OF THE INVENTION 
Hollow glass articles are conventionally mass-produced by introducing a gob 
of molten glass during each operating cycle of a glass-blowing apparatus 
into a premold in which a parison is formed by blowing or pressing. At the 
end of the cycle, the parison is transferred to a final mold where it is 
blown into the ultimate shape of the desired article during an immediately 
following cycle in which a new parison is formed in the premold, the 
sequence being then repeated. 
The length of an operating cycle is determined inter alia by the time 
required for the cooling of the parison to the proper temperature for the 
final blowing. If the parison is too hot during conversion into the 
finished article, the latter will tend to deform upon its extraction from 
the blow mold; if it is too cold, it may not attain its desired final 
shape in that mold. Thus, it is customary to transfer the parison from the 
premold to the final mold only after it has cooled down sufficiently and 
its temperature has been substantially equalized throughout its 
cross-section, such equalization being a relatively slow process because 
of the poor thermal conductivity of the glass. 
OBJECTS OF THE INVENTION 
An important object of our present invention, therefore, is to provide an 
improved process for speeding up the manufacture of hollow glassware by 
the two-stage process described above. 
A related object is to provide an apparatus for implementing this improved 
process. 
SUMMARY OF THE INVENTION 
In accordance with our improved process, a hot parison just formed in a 
premold is transferred in its heated state to a final mold in which it is 
allowed to reside for an extended cooling period while undergoing 
substantial equalization of its temperature by a flow of heat from the 
hotter core of its cross-section to its colder inner and outer surfaces. 
It is only after this cooling period that the parison is subjected in the 
same final mold to the blowing operation converting it into the desired 
article. 
During this extended cooling period, at least one new parison can be formed 
in the premold previously used and can then be transferred to another 
final mold for the ultimate blowing step, whereupon a further parison is 
produced in the premold for transfer to the first final mold after the 
article blown from the original parison has been extracted therefrom. 
An apparatus for implementing the process of our invention, therefore, 
comprises a plurality of blow molds associated with a single premold and 
positioning means for successively juxtaposing these blow molds with the 
associated premold in respective operating cycles, the apparatus further 
including transfer means for extracting a newly formed hot parison in each 
operating cycle from the premold and inserting it into the juxtaposed blow 
mold for cooling and temperature equalization, as described above, prior 
to its conversion into the finished article in a subsequent operating 
cycle. A turntable is advantageously used as the positioning means. 
As will be apparent, three or more final blow molds could be associated 
with a premold to extend the cooling period and/or to increase the number 
of parisons formed in the premold during the cooling period.

SPECIFIC DESCRIPTION 
In the drawing we have shown a premold 1 and two final blow molds 2 and 3, 
the latter being mounted in diametrically opposite positions on a 
turntable 4. The bed of the otherwise conventional and not further 
illustrated glass-blowing apparatus has been indicated at 5. 
The drawing also shows a parison 6 just formed in the premold 1 while a 
previously formed parison 6' resides in final mold 2 for an extended 
cooling period as discussed above. At the same time, mold 3 contains a 
finished article 6" (e.g. a bottle) which has just been blown therein to 
its final shape from a parison formed in a still earlier cycle. 
After the article 6" has been extracted from mold 3, turntable 4 is rotated 
through 180.degree. to juxtapose the empty mold 3 with the premold 1 
whereupon the parison 6 can be removed from the premold to the mold 3 by 
transfer equipment schematically indicated at 7. Such transfer equipment, 
well known per se, may comprise a gripper arm carrying a neck ring in 
which the upper end of the parison--which later becomes the neck of the 
finished bottle--is releasably clamped. In the same manner, mold 2 becomes 
available for a new parison for premold 1 after the cooled parison 6' has 
been shaped into a finished article and extracted. 
While the parison 6 is still quite hot at the time of its transfer from the 
premold to the adjacent final mold, its relatively large wall thickness 
limits any possible deformation at this stage; in any event, such 
deformation would have no effect upon the final shape to be subsequently 
imparted to it in the blow mold 2 or 3 in which it is initially received 
with clearance, as indicated for the parison 6', so as to expedite cooling 
and temperature equalization.