Glassware forming machines

There is described an improved method of cooling a blank mould used for the formation of a parison in glassware forming apparatus. Jets of cooling gas are delivered on to the outer mould surface through vertical rows of apertures and the gas which impinges on the outer mould surface is prevented from rebounding away from the mould surface but is caused to flow through a confined space close to the mould surface so that the cooling gas removes the boundary layer of air which is in contact with the outer mould surface and thereby markedly improves the cooling effect of the gas. Between the vertical rows of apertures there are provided vertical channels into which the cooling gas can expand and through which it will exhaust after it has effected cooling of the outer mould surface.

BACKGROUND OF THE INVENTION 
In glassware forming apparatus a gob of molten glass is fed to a blank 
mould in which there is formed a parison which is a first stage in the 
formation of an article of glassware such as a bottle or a jar. Because 
the blank mould is continually receiving gobs of molten glass the blank 
mould becomes heated to a high temperature and heat must be dissipated 
from the blank mould in order to provide for the extraction of a necessary 
quantity of heat from the gob during the formation of the parison. 
Conventionally, cooling of the blank mould is effected using a cooling gas, 
usually air. However, there exists, around the outer mould surface, a 
boundary layer of air which becomes heated to a temperature close to that 
of the outer mould surface and which is resistant to movement because of 
its closeness to the outer mould surface. Consequently this boundary layer 
of air constitutes an insulating layer which inhibits good heat transfer 
from the outer mould surface to the cooling gas. The boundary layer of air 
is penetrated by cooling gas where the cooling gas is directed at the 
outer mould surface, for example by jets. Provision has to be made for the 
cooling gas to exhaust between the jets and it has proved that adequate 
cooling of the blank mould by conventional means has required the use of 
either very high air pressures or very large volumes of the cooling air, 
both of which have their disadvantages. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and apparatus 
which enables a blank mould to be cooled in a more efficient manner so 
that a satisfactory cooling of the blank mould is achieved at relatively 
low air pressures and without the use of large volumes of cooling air. 
According to the present invention there is provided a method of cooling a 
blank mould used for the formation of a parison in glassware forming 
apparatus comprising the steps of delivering jets of cooling gas on to a 
substantially vertical outer mould surface through apertures the outlets 
from which are arranged in a series of substantially vertical rows, 
confining the cooling gas flow adjacent the said outer mould surface in 
the regions surrounding the outlets of the apertures through which the gas 
was delivered whereby the cooling gas is caused to disturb the air which 
contacts the said outer mould surface over areas substantially greater 
than the areas contacted by the jets, and thereafter causing the cooling 
gas to exhaust through a series of substantially vertical channels which 
are interspersed with the said rows. 
By confining the cooling gas flow adjacent to the outer mould surface 
immediately after delivery from the outlets of the apertures, the cooling 
gas is caused to perform a scrubbing action which removes the boundary 
layer of air from the outer mould surface over areas which are 
substantially greater than the areas of the jets themselves. This 
effective scrubbing action consequent upon the confinement of the cooling 
gas close to the outer mould surface results in a high heat transfer from 
the outer mould surface to the cooling gas over a series of substantially 
vertical areas or strips of the outer mould surface. The particularly 
efficient cooling of this series of substantially vertical areas of the 
outer mould surface leads to good cooling of the mould as a whole because 
the blank is relatively thick so that heat is readily conducted from the 
other parts of the mould into the vertical areas which are efficiently 
cooled by the method of the present invention. 
The good heat transfer from the outer mould surface to the cooling gas 
which results from the confinement of the cooling gas adjacent the outer 
mould surface immediately after delivery enables satisfactory cooling of 
glass bottle moulds to be obtained whilst avoiding the use of high volumes 
of cooling gas. 
The substantially vertical channels have a cross-sectional area which is 
large in relation to the cross-sectional area of the space within which 
the gas is confined adjacent the outer mould surface in order to effect 
the scrubbing action. The channels thus provide an exhaust path for the 
cooling gas, which offers little resistance to the gas flow. In 
consequence only a small back pressure exists as the gas passes into the 
vertical channels and therefore the presence of the vertical channels, 
interspersed with the vertical rows of apertures and the surrounding areas 
of gas confinement, is important in the provision of a cooling system for 
glassware forming apparatus which requires only a low pressure of cooling 
gas for good performance. 
The performance of the method in accordance with the present invention 
involves the use of a cooling means in conjunction with the glassware 
forming mould such that the surfaces of the cooling means and the mould 
together provide vertical areas where the surface of the cooling means is 
closely spaced from the outer mould surface, these vertical areas being 
interspersed with other vertical areas where there is a relatively wide 
spacing between the mould surface and the surface of the cooling means. 
While this relative positioning of the two surfaces can be achieved by the 
provision of some shaping on the outer mould surface, it is preferred for 
vertical ribs to be provided on the cooling means. 
The spacing of the surfaces of the vertical ribs from the outer mould 
surface must be kept a similar order of size to the diameters of the 
apertures in order for the advantages of the invention to be present. If 
the surfaces of the vertical ribs are too widely spaced from the outer 
mould surface in relation to the diameter of the apertures, the cooling 
gas will not be sufficiently confined adjacent the outer mould surface in 
order to disturb the air which is in contact with the outer mould surface 
by the scrubbing effect described above. On the other hand, if the 
surfaces of the vertical ribs are too close to the outer mould surface in 
relation to the diameters of the apertures, high pressures will be needed 
in order to force a sufficient volume of cooling gas between the opposed 
surfaces in order to effect adequate cooling. 
Advantageously, the surfaces of the vertical ribs are spaced from the outer 
mould surface by a distance in the range of 0.5 to 2.0 times the diameters 
of the apertures and preferably all the apertures have similar diameters. 
The widths of the surfaces of the vertical ribs are such that the edges of 
the ribs are separated from the edges of the apertures by a distance 
greater than the diameters of the apertures. Preferably the widths of the 
surfaces of the ribs are at least four times the diameters of the 
apertures.

DETAILED DESCRIPTION 
Referring to the accompanying drawings there is shown a main body portion 1 
of a blank mould. The main body portion 1 is the part of the blank mould 
which receives the gob of molten glass, and the blank mould is completed 
by the provision of neck rings upon the main body portion 1 or by the 
provision of both neck rings and an intermediate mould part upon the main 
body portion 1. 
The main body portion 1 of the blank mould is supported in a cooling insert 
2 which in turn is supported by a mould holder 3. As may be readily seen 
from FIG. 2 the cooling insert 2 presents to an outer mould surface 4 of 
the main body portion 1 a series of substantially vertical ribs 5 which 
are separated from one another by a series of substantially vertical 
channels or slots 6. The section through the cooling insert 2 which is 
illustrated in FIG. 1 is selected so as to show one of the substantially 
vertical channels 6 in the left-hand half of the Figure, and a rib 5 in 
the right-hand half of the Figure. The rib 5 has a surface the contour of 
which essentially matches the contour of that part of the outer mould 
surface 4 which the rib 5 faces, and the rib 5 has in it a substantially 
vertical row of apertures 7 for directing jets of air on to the outer 
mould surface 4. The apertures 7 through the ribs 5 are all circular 
apertures of the order of 1 mm in diameter and the ribs 5, which taper 
from top to bottom, have a width of 4 mm at the narrowest parts of their 
surfaces and a width of 5 mm at the widest parts. 
The substantially vertical ribs 5 and channels 6 extend as far down the 
inner surface of the cooling insert 2 as that part where the cooling 
insert 2 curves into a base portion of the insert 2 which base portion 
surrounds the bottom of the main body portion 1 of the blank mould. This 
base portion of the cooling insert 2 contains no channels but it does 
include further holes 8 and 9. The central hole 9 has a substantially 
larger diameter than the apertures 7 in the ribs 5, but the surrounding 
holes 8 in the base portion of the cooling insert 2 preferably have 
diameters of similar size to the diameters of the apertures 7. 
The volume between the cooling insert 2 and the mould holder 3, which, 
apart from a passage 10 in the centre of its base, is a solid member, 
forms a plenum chamber 11 from which cooling air under pressure may be 
directed through the apertures 7 and the holes 8 and 9 against the outer 
mould surface 4. 
In operation the passage 10 is connected to a source of cooling air which 
causes an increase of air pressure in the plenum chamber 11. In 
consequence cooling air is forced through the apertures 7 and the holes 8 
and 9. A vertical line of jets of cooling air issuing from the vertical 
row of apertures 7 in each rib 5 of the cooling insert 2 therefore strikes 
the outer mould surface 4 opposite to each rib 5. The spacing between the 
outer mould surface 4 and the similarly shaped surface of the rib 5 is of 
the order of one millimeter with the result that the cooling air from the 
jets issuing from the outlets of the apertures 7 is confined adjacent to 
the outer mould surface 4 in the regions immediately surrounding the areas 
of the impacts by the jets of air delivered from the apertures 7. The 
boundary layer of air contacting the outer mould surface 4 is consequently 
disturbed over areas substantially greater than the areas struck by the 
jets. 
Therefore substantial areas of the outer mould surface 4 opposite to the 
ribs 5 are scrubbed by the cooling gas which quickly takes up head from 
the outer mould surface before the cooling gas disperses sideways into the 
channels 6 on either side of each rib 5. The channels 6 are substantially 
vertically arranged and each lead into a shaped exhaust outlet 12 thereby 
providing for a ready discharge of the heated air from the space between 
the cooling insert 2 and the outer mould surface 4 of the main body 
portion 1. Each channel 6 has a substantially semi-circular cross section 
and a radius of the order of 5 millimeters. 
The base portion of the cooling insert 2 which contains the holes 8 and 9 
has a similar internal contour to the external contour of the base of the 
main body portion 1. However, the spacing between the external surface of 
the base portion of the main body portion 1 and the internal surface of 
the base portion of the cooling insert 2 is arranged to be of the order of 
2 millimeters when the main body portion 1 of the blank mould is cold. The 
greater expansion of the main body portion 1 in relation to the cooling 
insert 2 reduces this spacing to about 1.5 millimeters at the operating 
temperature. 
In the drawings the directions of air flow at different parts of the 
apparatus are indicated by arrows, of which arrow 12 in FIG. 1 shows the 
air flow through the passage 10 into the plenum chamber 11, arrows 13 and 
14 in FIG. 2 show respectively the air flow from the plenum chamber 11 
into one of the apertures 7, and the flow of the air after it emerges from 
the aperture 7, and arrows 15 and 16 in FIG. 1 show the movement of the 
air into one of the vertical channels 6 and out through the exhaust outlet 
12. 
Operation of the apparatus described with cooling air fed through the 
passage 10 to the plenum chamber 11 under a pressure of 30 pounds per 
square inch was found to give adequate cooling of a blank mould used for 
the manufacture of a parison as the first step of a two-stage glassware 
forming process for producing a jam jar. The effectiveness of the ribs 5 
in confining the cooling air adjacent to the substantially vertical outer 
mould surface 4 and producing good heat transfer is illustrated by the 
fact that jets of cooling air delivered through nozzles similar to the 
apertures 7 and similarly positioned approximately 1 millimeter from the 
outer mould surface, but unsupported by the surfaces of the ribs 5 and the 
channels 6 which alternate with the ribs 5, was found to give inadequate 
cooling of the blank mould even when the cooling air was projected through 
the nozzles under a pressure of 60 pounds per square inch. 
In an alternative arrangement in accordance with the present invention, 
satisfactory cooling of a blank mould was achieved using apertures 7 
having a diameter of 1.2 millimeters in ribs 5 having a surface of minimum 
width of 5 millimeters. The surfaces of the ribs 5, which had contours 
matching the contours of the adjacent portions of the outer mould surfaces 
4, were spaced 2 millimeters from the adjacent outer mould surface in this 
embodiment of the present invention.