Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present invention~relates to a method and an appara-
tus for evaporative cooling of tools of glass;~forming machines, for
instance plungers and molds, with a cooling liquid.
Known method and appara~us of this ~ype are described in
an article "Methoden der Formenkuhlung an Glasverarbeitungsmaschinen~
('~ethods for Cooling of Molds in Glass-forming Machines") by Rudolf
Wille, published in the magazin No. 7 "Konstruktion und Betrieb von
Glasverarbeitungsmaschinen" ("Cons~ruction and Operation of Glass-
fDrming Machines"), published by the Deutsche &lastechnische
Gesellschaft (German Society for Glass Technique), Frankfurt am Main,
. ; .
1961, pages 35 - 43. There a plurality of nipples, into which cool-
ing water is fed in the form of drops, are screwed locally into the
outer wall of the molt. This known way of cooling a mold has many
disadvantages. rne heat sinks, i.e. the nipples, are stationarily
arranged with regard to the mold surface. The diameter of each of
the nipples is necessary small and a mold provided with a plurality
of such nipples is relatively expensive. Such molds have to have
'i, a relatively great wall thickness in order to permit a threading
connection of the nipples and in order to obtain, in view of the
;,
small size of ~he heat sinks, by means of increased wall thickness
, .~.
¦ a sufficient temperature distribution over the entire moLd surface.
' While it is possible to provide a relatively grezt number of nipples
1 per surface unit, such an arrangement will evidently be rather ex-
pensive. The known mold has relatively large dimensions, due to
the necessary great wall thickness, the nipples threadingly connect-
ed thereto, an~ the neeessary feed conduits for feeding cooling
fluid to the nipples, which is especially detrimental when for the
j mounting of the mold, especially in molds for small hollow glass
bottles, ~nly limit~ s~rface areas are avallable. This particular-
ly holds for conditions where double gob molds are operated Caused
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!
by the design of tht? pr~dvc~i~n Inachlnes dc>~le gob molds are ar-
ran~ed so close to~ether that no ~ipple can be loc~ted in an area
which needs cooling most. AL1 additional disadvantage of ~his known
arran~ement is that water will c~l~ect a~ the bottom of the nipples
so that evaporation of the liquid will occur beneath the liquid level
and therefore under difficult conditionsO
At sufficiently large overheating of the liquid the danger
of film evaporatinn with a ~reatly reduced heat-transfer coefficient
exists (see the above referred Wille article, page 39, picture 8). ~!
Tnere exists further the difficulty to optimize the spatial arrange- ¦
ment of the heat sinks, since the heat sinks canno~ be in any desired !''~
manner distributed over the surface of the mbld. A cooling of the
mold bottom in a divided mold is not provided. In addition, thère
is no possibility to influ2nce at these known heat sinks the amount .
of the heat transfer.
According to another known method and apparatus (Austrian
; ` Patent No. 24,927) an adjustable amount of cooling liquid is dripped
Of squirted into the hollow wall of the mold. The thus formed water
vapor passes througb the cavity formed in the mold wall to cool the
latter. This method has the disadvantage that the water fed into
the mold, will im~inge anly onto a relatively small area of the mold
surface, A further disadvantage is the fact that the temperature of
the mold surface ~s so high that a vapor cushion develops beneath ~.
the infed water. As already expLained hereinabove in connection with
the Wille article, this cushion develops because the high temperature
difference between mold surface and water prevent6 the desirable so-
called bubble type evaporationO What actually occurs is the so-call-
ed fi~m evaporation, iOe. ~e formation of a continuous vapor film
between mold surface and water~(the Leidenfrost phenomenon), whlch
yields a much lower heat transfer coefficient than with bubble evap-
, .
- ~3771~7 i
orat; on~ rrh~ described cushit~n of the vapor f~Ll~ pr~vents ~he de-
sirable and necessarily hi~h heat extraction from the ~old. A cool-
ing of the remainder of the mold wall by convecting heat transfer by
means of water vap~r is, due to the small amount of ~vailable vapor
volume, not obtain3ble and therefore an essential improvement of the
cooling of the ~emainder of the mold wall cannot be expected. A sub-
stantially uniform temperature of the mold surface facing the gl~s~ ;
is not obtainable with this known cooling method, neither is it pos- I
sible to obtain sometimes desired temperature profiles onthe surface s
to be cooled, In addition the mold wall has to be hollow and rela-
tively thick, and requires therefore a relatively large space, which,
especially in modern cDmpact automatic glass forming machines, is
; not available. k
It is further known from the German Auslegeschrift , ;
2,150,193 to spray a cooling liquid directly onto the tool surface
to be cooled, which may be profiled.
An object of the invention is to improve the cooling of
the tools of glass-forming machines and to avoid especially film
evaporation of the cooling liquid during normal operation of the
tools.
With these and other objects in view, which will become
apparent as the description proceeds, the apparatus of the present
invention for cooling tools of glass-forming machines, especially
plungers and molds, mainly comprises cover means in contact with
and substantially covering the surface of the tool which is to be
cooled, and means for applying a cooling liquid to that surface of
the cover means which is opposite the surface thereof contacting the
tooL surface to be cooled, so th~ the liquid will evap~rate upon
contact with the opposite surf~ce of the cover means.
Preferably, according to the method of the present inven- -
.
~ lQ37r~17
tion, the differenc~ between the temperature of the surface of the
cover means which i5 contacted by the cooling liquid, on the one
hand, and the boiling point of the cooling liquid, on the other hand
(overheating), is held during the normal operation of the tool, in
the region of a critical temperature difference, at the border be-
tween bubble evaporation and film evaporation, and preferably in
the region of bubble evaporation.
The use of compressed air as coDling medium and the re-
rl!
sulting extreme noise can thus be avoided so that the invention con- i!' -
tributes to a more human atmosphere of the working environment.
The surface of the tool to be cooled can thereby have a
more or less great natural roughness, or it may purposely be profiled,~
for instance provided with cooling fins. This means that even exist~
ing mold equipment can be provided with cover means according to i;
the invention. The roughness or profiling may additinnally, or only,
be provided on the surface of the cover means which contacts the
. ;~ .
tool surface to be cooled. It is only necessary that between the
tool and the cover means a sufficiently large total area of contact
~ for the heat conduction will be maintained, which will prevent ac_
; 20 cumulation of heat in the tool wall, and which will assure to obtain
a desired magnitude of overhéating on the surface of the cover mean~ ;
which is contacted by the cooling liquid. When the cover means i8 .~
releasably connected to the tool, the tool may be used in a conven- ~t i
tional manner without cover means or in accordance with the present
invention. The application of the cooling liquid ontD the oover
means may be carried out in any desired manner.
The cover means may comprise a metal plate in contact with
the tool surface to be cooled, and this metal plate may be shaped
in accordance with said tool ~urface an~or may be continuous or may
be formed with perforations. Additionally, an intermediate layer
~ 5 ~
: ' :
` . ~a377l7
may be sandwiched between the metal plate and the tool surface in
contact wi~h the latter and the plateO The advantage of said inter-
mediate layer is that it all~ws to reduce the thickness of the metal
plate without reducin~ the desired heat transfer, In addition the
intermediate layer may be applied in order to affect the amount of
the contacting surface areas of tool and metal plateO The intermed-
iate layer may be formed from heat-resistant, non metallic material,
for instance be formed of glass or asbestos fibers. In such an ar-
rangement the intermediate layer may have a small thickness while
assuring a relatively great contact surface with sufficient heat
transfer. On the other hand, the intermediate layer may consist of
a wire mesh which will result in a re3-atively small contact ~urface k-
between the tool surface to be cooled on the one hand and themmetal
plate on the other hand. The cover means may also include a layer
applied to that surface of the cover means which is opposite the ;
surface thereof in contact with the tool surface to be cooled, and
the cooling liquid is then applied tothis layer so that the latter
will retain at least part of the cooling liquid and/or distribute
the same preferably by capillary action If this layer is not form~
retaining by itself, then an additional holding layer, for instance
a wire mesh, may be applied thereto. A distribution of the cooling
liquid by the cover means is especially desirable when the c~oling
liquid may be applied only to localized portions of~the cover mean8.
In 8uch case, the distribution layer will assure distribution of
the cooling liquid also to such portions of the cover means which
cannot be directLy re~ched by a spray of cooling liquid. In this
way, it i8 possible to withdraw heat uniformly from the outer sur-
face of the cover means by evaporation over a large surface area.
The attachment of t~e cover means may for instance be : .
carried out by welding or by riveting and such attachment is then
~Q37~717
advisable when the cover means can remain permanently connected to
the tool. On the other hand, the cover means may be releasably fast_
ened to the tool, whLch will make it possible to cool the tool in
the conventional manner or in accordance with the present invention.
Such releasable fastening will also facilitate repair of the cover
means and the tool. Advantageously, the cover means is attached to
the tool surface in such a manner that it may slightly shift along
the tool surface, which is especially necessary during intermittent
applicatLon of cooling liquid to the cover means which results in a
periodical heat expansion or contraction of the cover means relative
to the tool surface. In this case, the cover means i8 preferably
fixed at one point to the tool surface, so that the remainder of
j the coYer means may shift from this fixed point in all directions
. i
- relative to the tool surface. The attachment of the cover means to
the tool surface is preferably carried out in such a manner that
the cover mean9 may be pressed with a variable force against the
tool surface to be cooled so that the total area of contact between
cover means and tool surface and correspo~ ingly the magnitude of
,- the heat transfer may be varied. Such an arrangement is especially
. , j,..
advantageous when the cover means comprises a plurality of layers
which may thus be pressed to a varying degree against each other
and against the tool surface to be cooled. The cooling liquid pref-
erably consists essentially of pretreated, for instance desalted,
delimed and filtered water with a wetting agent, for instance a de_
tergent, methanol or ethanol. The means for applying liquid to the
cover means preferably comprises a plurality of spaced spray nozzles,
and the apparatus may also in~lude at least one temperature sensing
means engaging the c~vPr means for sensing the temperature of the
- latter, and means for controlling spraying of the cooling liquid
¦ 30 through the spray nozzles onto the cover means dependent on the temp-
7 ~
`-. 10377~7
erature sensed by t~ tem2erature sensing means.
The novel features which are considered as characteristic
for the invention are set forth in particular in the appended claims.
e invention itself, however, both as to its construction and its
method of operation, together wi~h additional objects and advantages
thereof, will be best understood from the following description of
specific embodiments when read in connection with the accompanying
drawing.
FIG. l is a longitudinal cross section of a blow mold half
with cover means applied to the outer surface thereof;
FIG. 2 is a cross section taken along the line II-II of ~
FIG. l; ~ ;
FIG. 3 is a longitudinal cross section similar to FIG. l 1~_,
and showing a different embodiment of the cover means; ~ ;
FIGS. 4 and 5 are partial transverse cross-sections of a
mold with different cover means applied to the outer surfaces thereof; ~ -
FIG. 6 is detail VI of FIG. 4, drawn to a considerably en- -
Larged scale;
FIG. 7 is a Longitudinal cross section of a further embodi~
ment of cover means applied to the outer surface of a blow mDld;
FIG. 8 is a circuit diagram illustrating the supply of
cooling fluid to a plurality of spray nozzles arranged about a blow
mold; and
FIG. 9 is a longitudinal cross section through a pres~
plunger with cover means applied to the inner surface of the hollow
plunger.
FIG. l illustrates one half 20 of a blow mold 23 in closed
condition in which the mold half shown-engages the bottom 25 of the
mold. The mold half 20 is su~pended in a gripper 26, onLy partial- ,
ly shown in FIG. l. , .
.
1~37~'7
Cover means 30 are applLed and held by screws 27 to the
outer surface of the mold half 20 and these cover means comprise an
_ intermediate layer 35 of non-metallic material, for instance glass
or asbestos fibers and an outer metal pLate 33
The cooling liquid is sprayed in form of spray cones 39
from a plurality of spray nozzles 37 onto the outer surface of the
.; metal plate 33 at which the cooling liquid evaporates.
; Pretreated water with an additional wetting agent such as
a detergent, methanol or ethanol i8 preferably used as cooling Liquid
As shown in FIG. 2, the intermediate layer 35 and the out-
` er m~tal plate 33 are bent according to the outer contour of the
mold half 20 and cover substantially the outer surface of the latter.
il It Ls to be understood that the other mold half, not shown
in FIGS. 1 and 2, is provided in a similar manner with cover means
onto which the cooling liquid is sprayed.
. - FIG. 3 illustrates a blow mold half 40 which, in a maffner
5imilar as the above described blow mold half 20, is provided with
i c~ver means 41 which comprises a metal plate 43 and a wire mesh 45
i~; sandwiched between the metal plate 43 and the outer surface of the
, 20 mold half 40. The co~er means 41, comprising the metal plate 43
- and the wire mesh 45, is in a central region fastened to the mold
half 40 by a centering screw 47. The cover means is further held
; I
! onto the outer surface of the mold half 40 by a plurality of addi-
:,. I
~ tionaL screws 49, which pass through the cover means 41 with suffic-
¦ ient clearance or play. These screws 49 serve to press the cover
means 41 in a desired manner against the outer surface of ~he mold
half 40, to influence in this way the magnitude of the contact sur-
faces between the wire mesh 45 and the outer surface of the mold
¦ half 40, on the one hand, and the wire mesh 45 and the metal plate
43, on the other hand. In this way, the magnitude of the heat con-
_ g _ ,
~, " .
~)377î7
duction between the mold half 40 and the surface 50 of the cover
means 41 which is contacted by the cooling liquid may be influenced.
Due to the clearance around the screws 49, the cover mRans 41 may
8hift Ln all directions from the centering screw 47 relative to the
outer eurface of the mold half 40 and such movement is necessary at
: different heat expansion of the mold half 40 and the cover means 41.
FIG. 4 partially illustrates a mold 53, the inner surface
~ .
- 54 of which i8 periodically contacted with hot glass, and to the out-
er surface of wh~hh a cover means 57 comprising a metaL plate 55 is
applied The metal plate 55 is pressed against the outer surface of
. ,~,,
the mold 53 by means of screws 59, only one of which is shown in FIG.
. , 4.
I FIG. 5 illustrates a similar, but modified arrangement in
; ~ .
` which the cover means 60 comprises besides the metal plate 55, an
¦ outer layer 63 applied thereto. The outer layer 63 is constituted
! by a wire mesh which has the ta~sk to prevent immediate run-off of
the cooling fluid applied thereagainst and/orAto distribute the cool-
-~ ing fluid over the outer surface of the metal plate 5-5.
;tll FIG. 6 illustrates a detail of FIG. 4 at a greatly enlarged
l g 20 8cale, and as can be seen from FIG. 6 the inner surface 65 of the
metal plate 55 is relatively smooth, whereas the outer surface 67
of the mold half 53 is very rough. The sum of all partial contacts
between the mold 53 and the metal plate 55 in the region of the
points of the rough surface 67 constitutes the total contact surface
through which heat conduction from the moLd 53 to the metal plate
55 takes place.
j FIG. 7 illu~trates a further modification in which a mold
half 70 is provided on its outer surface with cover means 71. The
cov r means 71 comprises an intermediate layer 73 in form of a wire
mesh, a metal plate 75, and an outer layer 77 which may consist of
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- . ~ . - . .
037717'
non-metallic material, such as for instance glass or asbestos ibers
and a holding layer 79 in the form of a coarse wire mesh superimposed
thereupon. The holding layer 79 has the task to prevent damage to
the layer 77 which serves to hoLd and to properly distribute the
cooling liquid, and to hold the layer 77 uniformly against the metal
plate 75. The cov~r means 71 is again fixed on the mold half 70 by
a centering screw 80, whereas other screws 81, passing with clearance
through cover means 71, serve to press the cover means 71 with the
desired pressure onto the mold half 70.
FIG. 8 schematically illustrates a circuit diagram for
P supplying a plurality of nozzles arranged about a blow mold lZ0 with
. i cooling liquid. me cooLing Liquid, preferabLy pretreated water with
a wetting agentJ is taken from a tank 90 and pumped by a pump 93
through a filter 91 into a conduit 95 which is protected by a pres-
~! 8ure limiting valve 96. The cooling liquid passes from the conduit
., j
; 95 into three branch conduits 98, 99, and 100 in which pressure reg- -
ulating valves 103, 104 and 105 are respectively arranged. In each
of the branch conduits 98, 99 and 100 is further arranged a two-way-
two~position valve 108, 109, 110, respectively.
me branch conduit 98 is connected to lower spray nozzles
113, only two of which are shown in the drawing, the branch conduit
)l'~ 99 is connected to intermediate spray nozzles 115 of which also only
two are sh~ n, and the branch conduit 100 is connected to the upper
~pray nozzles 117. The liquid sprayed through the nozzles serves
to cool blow mold 120 which comprises a mold bottom 121, two blow
mold hal~es 123 and 124 and two neckring halves 126 and 127. The
blow mold halves 123 and 124 as well as the neckring halves 126 and
127 are respectively provided with cover means 129, 130, 131 and 132,
onto which the spray nozzles 113, 115 and 117 spray the cooling
liquid.
:
- 103'7717
. .
The arrangement comprises further a temperature sensing
means 135, which may for instance be in contact with the outer sur-
~ace of the cover means 129, and which is connected by a conductor
137 to an input of a controller 140. The arrangement preferably
comprise also a position switch 141 which is connected by a conduct-
or 143 to a further input of the controlled 140. Three conductors
. 145, 146, 147 respectively connect outputs of the controller 140 with
. ~ electromagnets of the electromagnetically operated valves 108, 109
. and 110.
As soon as the mold halves lZ3 and L24 reach, during the
. - ~,.
operating cycle of the.machine, a position in which spr~ying is to
start, the position switch 141 produces a signal which is transmitted
; to the controller 140. I~e controller 140 thereupon controls over
the conductors 145, 146 and 147 the valves 108, 109 and 110, and
.. switches these valves to an open position, as shQwn in FIG. 8, in
.: - which the spray nozzles 113, 115 and 117 are supplied with cooLing
' liquid and spray such cooling liquid onto the mold 120. The time
, .
of spraying through the individual nozzles is controlled by the temp-
.~ erature sensing means 135 which will cause switching of the valves
.~ ~ 20 108, 109 and 110 to the closed position when the temperature sensing ~ -
!ll means 135 senses a temperature lower than a predetermined value,,
. . I .
that is when the cooling of the mold 120 is sufficiently advanced.
i EvidentLy, it is also possible to provide a plurality of temperature
; 1 sensing means at different locations of the moLd 120 so that spray-
ing of cooling fluid onto different portions of the mold 120 may
' be individually controlled,
.. FinalLy, FIG. 9 illustrates a press plunger 150 of a glass
molding machine which is hollow and which is pro~ided at its inner
surface, that is the surface thereof which is opposite from the sur-
face contacting during operation of the press plunger the molten
- 12 _ ~.
~ C~37 ~ ~17
glass, with a cover 151, which is held in the interior of the press
plunger 150 in contact with the inner surface thereo~ by a threaded
ring 153. The ring 153 carries by means of spokes 155 a spray noz-
zle 157 through which cooling liquid Ls sprayed onto the inner sur-
face of the cover m~ans 151. It is to be understood that the cover
means 151 can be, in a manner similar as described before, constitut-
ed by a plurality of layers and be fastened to the inner surface of
the press plunger by a pluraLity of screws or the like.
It will be understood that each of the elements described
above, or two or more together, may also find a useful application
in other types of apparatus for cooling tools, especially plunger~
and molds of glass forming machines differing from the types describ-
ed above.
While the invention has been illustrated and described as
!1 embodied in an a~paratus for cooling tools of glass forming machines
in which the tool surface to be cooled is substantially covered by
; . . ............ ..
` cover means held in contact with the tool surface a~ in which cool-
ing liquid is sprayed against the cover means, it is not intended to
` be limited to the details shown, sLnce various modifications and
structural changes may be made without departing in any way from the
spirit of the present invention.
~!
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