U.S. patent application number 13/884954 was filed with the patent office on 2013-09-19 for controlled container headspace adjustment and apparatus therefor.
The applicant listed for this patent is David Murray Melrose. Invention is credited to David Murray Melrose.
Application Number | 20130239522 13/884954 |
Document ID | / |
Family ID | 46084261 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130239522 |
Kind Code |
A1 |
Melrose; David Murray |
September 19, 2013 |
CONTROLLED CONTAINER HEADSPACE ADJUSTMENT AND APPARATUS
THEREFOR
Abstract
A sealing and pressure dosing apparatus, and container filling
method, including a capping machine (102) which receives containers
(1). Closures (80) are applied to the containers (1) immediately
following the raising of pressure within the containers (1) by a
pressure dosing system in a pressure sealing changer (84).
Preferably a cooling system is integrated with the capping
machine.
Inventors: |
Melrose; David Murray; (Mt.
Eden, NZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Melrose; David Murray |
Mt. Eden |
|
NZ |
|
|
Family ID: |
46084261 |
Appl. No.: |
13/884954 |
Filed: |
November 18, 2011 |
PCT Filed: |
November 18, 2011 |
PCT NO: |
PCT/NZ11/00243 |
371 Date: |
May 11, 2013 |
Current U.S.
Class: |
53/467 ;
53/285 |
Current CPC
Class: |
B65D 1/0261 20130101;
B67C 7/0086 20130101; B65D 1/0223 20130101; B65D 79/005 20130101;
B65D 47/121 20130101; B67B 3/20 20130101; B67C 3/14 20130101; B65B
3/04 20130101; B67C 7/008 20130101; B67C 3/222 20130101; B67B
2201/08 20130101; B67C 7/00 20130101 |
Class at
Publication: |
53/467 ;
53/285 |
International
Class: |
B65B 3/04 20060101
B65B003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2010 |
NZ |
589386 |
Mar 4, 2011 |
NZ |
591553 |
Claims
1. A sealing and pressure dosing apparatus, including a sealing
machine including a driven turret for serially receiving a
plurality of containers, at least one sealing head for applying
seals to said containers as said containers are moved about in a
path by said turret, a pressure sealing chamber for isolating a
neck finish end of said containers and accessing the headspace of
said containers, said pressure sealing chamber providing a pressure
dosing system for raising the pressure within said containers
received by said sealing machine prior to sealing by a respective
seal applied thereto, said pressure dosing system being integrated
with the sealing machine, said apparatus being further provided
with a container cooling system to bring at least part of an
outside wall of the container to a temperature below approximately
75.degree. C.
2. A sealing and pressure dosing apparatus as claimed in claim 1,
wherein said sealing machine is rotary and said driven turret is
rotatable, said containers being moved in a substantially circular
path.
3. A sealing and pressure dosing apparatus as claimed in claim 1 or
claim 2, wherein said pressure is raised immediately prior to the
sealing by a respective seal.
4. A sealing and pressure dosing apparatus as claimed in claim 3,
wherein said sealing machine is a capping machine, and said seals
are caps or closures.
5. A capping and pressure dosing apparatus as claimed in claim 4,
wherein said containers are filled with a heated liquid above
80.degree. C.
6. A capping and pressure dosing apparatus as claimed in claim 5,
wherein said container cooling system is integrated with the
capping machine.
7. A capping and pressure dosing apparatus as claimed in claim 6,
wherein the cooling system maintains a temperature below
approximately 60.degree. C. on at least a part of an outside wall
of the container.
8. A capping and pressure dosing apparatus as claimed in claim 6,
wherein the cooling system maintains a temperature above
approximately 75.degree. C. on at least a part of an inside volume
of the container.
9. A capping and pressure dosing apparatus as claimed in claim 6,
wherein the cooling system maintains a temperature above
approximately 80.degree. C. on at least a part of an inside volume
of the container.
10. A capping and pressure dosing apparatus as claimed in claim 6,
wherein the cooling system maintains a temperature above
approximately 85.degree. C. on at least a part of an inside volume
of the container.
11. A sealing and pressure dosing apparatus as claimed in claim 1,
wherein said sealing chamber seals said containers under a neck
support ring.
12. A method of filling a container with a fluid including
introducing the fluid through an open end of the container so that
it, at least substantially, fills the container, heating the fluid
before or after its introduction into the container, providing a
seal or cap, providing an opening or aperture between said seal or
cap and said container, providing at least one liquid and/or gas
through the opening or aperture, sealing the opening or aperture
under increased pressure conditions, so as to compensate for
subsequent pressure reduction in a headspace of the container under
the seal or cap following the cooling of the heated contents, and
forcibly cooling at least a part of outside walls of said
containers substantially immediately after sealing or capping said
containers to bring at least part of an outside wall of the
container to a temperature below approximately 75.degree. C.
13. A method as claimed in claim 12 wherein said cooling occurs
substantially within one minute of said sealing or capping.
14. A method as claimed in claim 12 in which the at least one
liquid and/or gas passes through the opening or aperture under
pressure.
15. A method as claimed in claim 12 in which the container is
positioned in a pressurizing means.
16. A method as claimed in claim 12 in which the at least one
liquid and/or gas is a heated liquid or steam injected through the
opening or aperture.
17. A method as claimed in claim 12 in which the opening or
aperture is provided with a temporary or partial seal through which
the at least one liquid and/or gas is provided.
18. A method of filling a container with a fluid including
introducing the fluid through an open end of the container so that
it, at least substantially, fills the container, heating the fluid
before or after its introduction into the container, applying a
seal or cap to said container, providing an opening or aperture in
said seal or cap, providing at least one liquid and/or gas through
the opening or aperture, sealing the opening or aperture, so as to
compensate for pressure reduction in a headspace of the container
under the seal or cap following the cooling of the heated contents,
and further including forcible cooling of said containers to bring
at least part of an outside wall of the container to a temperature
below approximately 75.degree. C.
19. A method as claimed in claim 18 wherein cooling of said
containers includes cooling at least a part of outside walls of
said containers substantially immediately after sealing or capping
said containers.
20. A method as claimed in claim 19 wherein said cooling occurs
substantially within one minute of said sealing or capping.
21. A method as claimed in claim 18 in which the opening or
aperture is provided within said seal or cap with a temporary or
partial seal through which the at least one liquid and/or gas is
provided.
22. A method as claimed in claim 21 in which said seal or cap has a
liner material on an inside surface, said liner temporarily sealing
the opening or aperture.
23. A method as claimed in claim 18 in which the opening or
aperture is sealed under elevated pressure conditions.
24-26. (canceled)
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to a sealing and
pressure dosing apparatus and more particularly to a capping and/or
sealing apparatus for applying closures to containers at high
speed, and even more particularly to a capping apparatus including
a pressure dosing system for providing a pressure medium into a
head space of each of the containers prior to closure application
by the apparatus. The pressure sealing may be undertaken either
during the initial sealing of the container, or as a secondary
operation after the initial sealing the container. The headspace
pressurization increases the internal pressure within the
container, providing for increased top-load capability of the
container. This invention may further relate to hot-filled and
pasteurized products packaged in heat-set polyester containers and
for controlling the cooling of any containers filled with a heated
liquid.
BACKGROUND
[0002] The present invention in one particular embodiment is
directed to a capping apparatus including a pressure dosing system
which has been specifically configured to overcome shortcomings
associated with previously known arrangements by effecting
injection of any medium, for example gas, liquid, steam or any
combination into containers essentially at about the time of the
application of a closure to each container by the apparatus.
[0003] In the present specification, including the claims, the term
"fluid" covers both liquids and gases unless the context clearly
indicates otherwise.
[0004] Gaseous nitrogen is one utility used in the food and
beverage industry to expel oxygen from products and increase shelf
life.
[0005] However, as the nitrogen disperses immediately upon
injection, the process for controlling accurate dosing is limited.
Some of the nitrogen will escape prior to capping, thus rendering
the process inexact in terms of absolute pressurisation control.
Additionally, handling nitrogen systems can be costly and
dangerous.
[0006] Nitrogen consumption can be reduced by as much as 80% using
a liquid nitrogen dosing system instead of gaseous nitrogen
tunnels, but as the capping or sealing of the container occurs at
ambient pressure at the precise time of sealing, in both systems,
the resulting pressure value is compromised. At the instantaneous
moment of sealing, the pressure value can only be equal to ambient
pressure. Following capping there is a subsequent rise in internal
pressure as the nitrogen continues to expand but cannot escape the
sealed container. However, as the nitrogen is dosed prior to
sealing there is a loss of some of the nitrogen dose prior to
sealing, the amount of which varies according to many factors. This
leaves the process inexact in terms of identifying the dose
actually in the container after sealing. It is accepted that this
will always be a value less than the dose introduced to the open
container prior to sealing.
[0007] The use of nitrogen, however, does provide for a build-up of
internal pressure within a container following capping. This is
more practical in the case of beverages filled into the container
cold, than when used in conjunction with hot fill beverages. In
both cases it is possible that all dosed nitrogen disperses prior
to sealing the container, for example if there is a stoppage on the
line post dosing and prior to capping. Additionally, the dosing
process becomes even more difficult to control in the hot fill
environment, particularly at fast line speeds. When nitrogen is
introduced into a container under ambient pressure conditions and
on top of a heated liquid, the nitrogen will be much more volatile
than if the liquid is cold. It will disperse much more quickly
prior to capping or sealing leaving the consistency of dose much
more uncertain.
[0008] Plastic bottles need to be pressurized at all line speeds,
and if control over the exact pressure achieved inside a container
is compromised then the speed of the system will also be
compromised in order to correctly pressurise each container.
[0009] Another aspect to consider is consistent container fill
levels. If container headspace varies because the fill levels are
wildly different, the final bottle pressures also will be wildly
different. For example, suppose the bottle had an 18 fl oz fill
with a 1 fl oz headspace, and the next bottle on the production
line had a fill of 18.3 fl oz (610 ml) with a 0.6 fl oz (20 ml)
headspace. Both bottles receive a 0.001411 oz charge of liquid
nitrogen. The liquid nitrogen dosing is consistent; however, in
accordance with basic gas laws, the final bottle pressure on the 18
fl oz fill is 17 psig and the bottle with a 18.3 fl oz fill has
25.5 psig final pressure. Many factors determine final bottle
pressure accuracy in addition to the dosing equipment accuracy.
They include container volume consistency and good sealing
closures. All factors must be addressed for good results.
Conventionally, the dosage of liquefied gas dispensed into a
container is based on an average expected fill level of the
containers in a continuous fill operation. Using this method, any
variation in head-space volume due to variations in fill level
would cause under and over pressurized containers.
[0010] The abovementioned concerns are even greater when used with
hot filling liquids into containers. When PET containers are filled
with a heated liquid, the bottles are transported through a filling
machine by means of a conveying device and a heated liquid is
generally introduced to the container. Alternatively, a cool liquid
may be introduced that is subsequently heated after the container
has been capped or sealed.
[0011] So called `hot fill` containers are well known in prior art,
whereby manufacturers supply PET containers for various liquids
which are filled into the containers and the liquid product is at
an elevated temperature, typically at or around 85 degrees C. (185
degrees F.).
[0012] The container is manufactured to withstand the thermal shock
of holding a heated liquid, resulting in a `heat-set` plastic
container. This thermal shock is a result of either introducing the
liquid hot at filling, or heating the liquid after it is introduced
into the container. In typical prior art filling situations,
containers are filled with a heated liquid above 70.degree. C., and
more often subjected to filling temperatures of between 70.degree.
C. and 95.degree. C. Once capped, or in other words sealed, the
product must be maintained at a certain high temperature for a
certain critical time in order to complete the process of
pasteurization within the container. Even further, the container
must also be inverted or at least tipped sideways for a certain
time in order to sterilize the underneath of the seal or cap.
[0013] It is preferable for example to maintain a temperature of
above 80.degree. C. for a 2 minute period after sealing for many
beverages prior to starting the cooling process. Therefore the
typical cooling of containers to bring them down to around
30.degree. C. does not start until at least some time after the
inversion of the container so that the core temperature of the
liquid within the container is maintained high enough to sterilize
the underneath of the cap and complete sterilization of the
internal container contents.
[0014] Once the cooling process is finally allowed to be deployed
on the container it is usually cooled rapidly in a heat exchanger
or cooler in order to provide a container that may be subsequently
labelled and packed into boxes or the like for transportation away
from the filling line.
[0015] Therefore, in prior art it is not considered feasible to
provide cooling simultaneously with the capping of filled
containers, or the temperature of the contents is compromised
before it may be utilized for internal sterilization purposes. Not
only would there be substantial risk in introducing foreign matter
into the container prior to sealing, but the temperature of the
product would be compromised and the efficacy of the pasteurization
model would be corrupted.
[0016] Once the liquid cools down in a capped container, however,
the volume of the liquid in the container reduces, creating a
vacuum within the container. This liquid shrinkage results in
vacuum pressures that pull inwardly on the side and end walls of
the container. This in turn leads to deformation in the walls of
plastic bottles if they are not constructed rigidly enough to
resist such force.
[0017] The present invention relates to both cold and hot-fill
containers and may be used by way of example in conjunction with
the hot fill containers described in international applications
published under numbers WO 02/18213 and WO 2004/028910 (PCT
specifications) which specifications are also incorporated herein
in their entirety where appropriate.
[0018] The PCT specifications background the design of hot-fill
containers and the problems with such designs that were to be
overcome or at least ameliorated and in particular the use of
pressure compensation elements.
[0019] Those skilled in the art will be aware of several container
manufacturing heat-set processes for improving package
heat-resistant performance. In the case of the polyester,
polyethylene terephthalate, for example, the heat-setting process
generally involves relieving stresses created in the container
during its manufacture and to improve crystalline structure.
[0020] In hot filling of beverages in PET containers, the thermal
stability of the material of the container also constitutes a
challenge. PET has a low glass transition point of approximately 75
degrees C. When the headspace of a container is pressurized while
the liquid contents are above about 70 degrees C., the container
walls are subjected to particularly damaging forces. This occurs
following the capping of a lightweight container filled with a
heated liquid, even when additional pressure is not applied to the
container. The build-up of pressure comes from the headspace
increasing in temperature immediately following capping and
exerting expansion forces against the lightweight surfaces of the
container.
[0021] In the current art for both cold and hot filled beverage
applications, the containers may be conveyed through a
nitrogen-dosing unit where nitrogen may be dripped into the
unsealed bottles and shortly afterwards the bottles are sealed.
This method is also referred to as the nitro-dose process.
Liquefied gas may be injected by an apparatus such as that
disclosed in US Patent Application No. 2005/011580 A1 to Siegler et
al., which is incorporated herein by reference in its entirety.
Liquefied gas may alternatively be dripped in by an apparatus such
as that disclosed in U.S. Pat. No. 7,219,480 to Winters et al,
which is also incorporated herein by reference in its entirety.
[0022] In such nitro-dose applications there is significant
container distortion when the PET material is above about
70.degree. C. to 75.degree. C. due to the high level of nitrogen
pressure within the container. Such distortion is non-recoverable.
The container effectively grows in volume and the base is
disfigured and unstable.
[0023] Also for example, structures in the sidewall, such as
ribbing, may be similarly affected causing uncontrolled container
growth and distortion. This distortion causes a weakness in any
strengthening structures and is very undesirable.
[0024] Typically, at present, hot closed bottles will be
transported to the bottle cooler preferably by means of at least
one conveyor belt. In the cooling device or heat exchanger, the hot
bottle is cooled down close to room temperature or to around
30.degree. C. to 35.degree. C.
[0025] Typical hot fill operations utilize ambient water to slowly
cool hot filled packages after they are sealed, until they return
to ambient temperature. This usually occurs several minutes after
the product has been filled into the container, whereby the
container walls are subjected to temperatures above the glass
transition point of PET.
[0026] The temperature of the filled contents take a period of time
to cool from a typical 85-95 degrees C. of fill temperature to
below approximately 60 degrees C. At 60 degrees C. and below the
PET does not distort under stress of internal pressure in the way
it does above its glass transition point.
[0027] My PCT patent specification WO 2005/085082 describes a
previous proposal for a headspace displacement method which is
incorporated herein in its entirety where appropriate by way of
reference.
[0028] Where reference in this specification is made to any prior
art, this is not an acknowledgment that it forms part of the common
general knowledge in any country or region.
OBJECTS OF THE INVENTION
[0029] It is thus an object of the present invention in its various
embodiments to overcome or at least alleviate problems in prior art
proposals to the present time.
[0030] A further and alternative object of the present invention is
to at least provide the public with a useful choice.
SUMMARY OF THE INVENTION
[0031] According to one aspect of the present invention, there is
provided a sealing and pressure dosing apparatus, including a
sealing machine including a driven turret for serially receiving a
plurality of containers, at least one sealing head for applying
seals to said containers as said containers are moved about in a
path by said turret, a pressure sealing chamber for isolating a
neck finish end of said containers and accessing the headspace of
said containers, said pressure sealing chamber providing a pressure
dosing system for raising the pressure within said containers
received by said sealing machine prior to sealing by a respective
seal applied thereto, said pressure dosing system being integrated
with the sealing machine.
[0032] Preferably, a capping and pressure dosing apparatus
embodying the principles of the present invention includes a rotary
capping machine including a rotatable driven turret for serially
receiving a plurality of containers, typically bottles. The
apparatus of the present invention includes a pressure dosing
system including a sealing chamber which is positioned to isolate
and seal the upper neck finish of the containers and the mouth of
each container as the container moves through the capping machine.
By this arrangement, pressure control is highly optimized,
enhancing operating efficiency. In the preferred form, operation of
the pressure sealing system is electronically coordinated with
operation of the capping machine to facilitate consistent
operation, permitting the pressure system to be operated either
continually, or intermittently, as desired.
[0033] Preferably, the rotary capping machine of the apparatus
includes a plurality of capping heads for applying closures to
respective ones of the containers as the containers are moved about
a generally circular path by the rotary turret of the capping
machine. The capping machine may be of a generally conventional
configuration, with associated rotary conveyors, or starwheels,
operatively associated with the capping machine for supplying
filled, but unsealed containers to the machine, and for receiving
filled and sealed containers from the machine.
[0034] The pressure dosing system of the present invention is
configured for pressurizing the head space of each of the
containers received by the capping machine simultaneously with the
application of a respective closure thereto. As is known by those
familiar with the art, the head space of a container is that upper
region of a container which is unfilled with the typically liquid
contents of the container. Injection of pressure into this region
of containers having non-carbonated contents desirably acts to
enhance package for more secure handling, stacking, and dispensing
(such as from vending machines) of products, and desirably acts to
enhance the freshness and flavor of the package contents if an
inert gas such as nitrogen is utilized for example.
[0035] Significantly, the present apparatus preferably is
configured to effect pressure injection at, or in close
relationship to, the so-called capping head of the capping machine,
that is, the point at which the package is positioned for closure
application. As will be appreciated, this is in significant
distinction from systems employed heretofore, where nitrogen has
typically been injected into containers well before closure
application, typically before the containers were even received by
a capping machine or where liquid nitrogen has typically been
injected into containers under ambient pressure conditions and thus
being susceptible to immediate expansion out of the container prior
to actual sealing by capping.
[0036] To this end, the pressure dosing system of the present
apparatus preferably includes a pressure sealing chamber connected
to the capping head within the circular path about which the
containers are moved by the capping machine, at a position over
each container and the respective one of the closures held by one
of the capping heads. The pressure dosing system includes a control
valve to selectively permit intermittent or continuous dispensing
of pressure medium, for example highly filtered air or steam, with
a control system provided for coordinating operation of the
pressure dosing system with operation of the capping machine.
[0037] The pressure sealing chamber preferably defines a downwardly
connecting sealing surface for engagement with either the upper
part of each container or the cap of each container. By this
configuration of the sealing chamber, pressure medium is directed
downwardly through the open mouth of each container as it is being
moved by the capping machine, with closure application initiated
simultaneously after each container is moved passed the capping
head.
[0038] Turning then to the situation whereby nitrogen liquid is
dropped into a hot-filled bottle, it will be appreciated that
following capping an immediate and severe increase in both
temperature and pressure is experienced against the sidewalls. With
the container walls experiencing temperatures of between 85.degree.
C. and 95.degree. C. in most situations, and a need to maintain
this temperature above 80.degree. C. for up to 2 minutes to
complete pasteurization after capping, it will be appreciated that
the walls of the container will be severely stressed while above
70.degree. C. in the case of PET as this is the glass transition
temperature.
[0039] The present invention may therefore provide for immediate
cooling of the walls of the container, even prior to the rise in
internal pressure within the container, and does so in a manner
allowing the internal product temperature to be maintained above
approximately 80.degree. C. for up to approximately a 2 to 3 minute
period. In other words, the present invention in another aspect
provides a method of pressurizing a container filled with a heated
liquid and controlling a differential temperature between the
sidewalls of the container and the internal contents of the
container.
[0040] In this way, the sidewalls may be kept at a temperature
below approximately 70.degree. C. in the case of PET, while
maintaining a higher internal temperature of between 80.degree. C.
and 95.degree. C.
[0041] According to a further aspect of the present invention there
is provided method of filling a container with a fluid including
introducing the fluid through an open end of the container so that
it, at least substantially, fills the container, heating the fluid
before or after its introduction into the container, providing a
seal or cap, providing an opening or aperture between said seal or
cap and said container, providing at least one fluid through the
opening or aperture, sealing the opening or aperture under
increased pressure conditions, so as to compensate for subsequent
pressure reduction in a headspace of the container under the seal
or cap following the cooling of the heated contents, and cooling at
least a part of outside walls of said containers substantially
immediately after sealing or capping said containers.
[0042] According to a still further aspect of the present invention
there is provided a method of filling a container with a fluid
including introducing the fluid through an open end of the
container so that it, at least substantially, fills the container,
heating the fluid before or after its introduction into the
container, applying a seal or cap to said container, providing an
opening or aperture in said seal or cap, providing at least one
fluid or gas through the opening or aperture, sealing the opening
or aperture, so as to compensate for pressure reduction in a
headspace of the container under the seal or cap following the
cooling of the heated contents.
[0043] The present invention may also provide a lower pressure
environment within the container immediately after sealing.
Typically in a nitrogen dose method, the container will experience
pressures of between 15 psi and 30 psi during the first 2 minutes
after sealing. In the present invention, the pressure may be
modified downwardly to between 1 psi and approximately 8 psi. This
significantly reduces internal stresses on the container while the
product must be maintained at high temperature to complete
pasteurization after sealing.
[0044] To summarise, in prior art situations, once a heated liquid
is filled into the container the material of the container walls,
for example Polyethylene Terephthalate (PET), will experience a
rapid rise in temperature. Once the material temperature rises
above the glass transition value, for example above 70.degree. C.
in the case of PET, the sidewalls are subject to severe distortion.
This distortion force will be present until the container is able
to be cooled to bring the core temperature of the product down to
below approximately 70.degree. C. and more typically to
approximately 30.degree. C. following a period of time in a cooling
heat exchanger.
[0045] In the current art of filling hot or heated beverages, the
bottom and sides of the bottles may be rapidly cooled anywhere in
the filling line from the blow moulding machine through to the
filling machine and through to the labelling process by means of
air or water jets. This process is designed to lower the internal
temperature of the container contents.
[0046] US Patent Application No. 2007/0125742 to Simpson et al.,
which is incorporated herein by reference in its entirety,
describes the step of placing the container in a cooling apparatus
after capping.
[0047] US Patent Application No. 2007/0184157 A1 to Stegmaier,
which is incorporated herein by reference in its entirety,
describes a process for hot filling and quick chilling a container
after capping, in particular to retain maximum flavour profiles
following acceptable sterilisation procedure after capping
containers.
[0048] Also well known in the current art is the method of blowing
or forcing air onto containers after filling and capping, and often
to either cool bottles or dry them. In the case of pressurised
containers it is well known that removal of liquid droplets from
the surface of the container as quickly as possible removes stress
concentration points on the surface of the container.
[0049] The present invention provides for not only a lowering of
internal pressure to below approximately 10 psi, and more
preferably to between 5 psi and 10 psi, and even more preferably to
between 1 psi and 5 psi, but the present invention may also provide
for a method of differentially cooling the outside walls of a
container immediately prior to capping or during capping and for a
controlled period afterwards to ensure correct product
pasteurization and for the sidewalls to be simultaneously protected
from excessive force.
[0050] In the present invention, the pressure is raised within the
container to minimal levels, and the cooling process of the
container may be started earlier than in prior art. In the present
invention the cooling process may be undertaken within the capping
or sealing device itself, which has not been described, developed
or achieved before in the art.
[0051] More particularly, in the present invention, the outside
shell of the filled container may be temperature controlled to
ensure a maximum internal temperature is retained for any given
time period, while maintaining a differential temperature on the
outside surface or shell. The application of such control allows
for some products to be cooled in a minimum time to retain maximum
flavour profiles, or to be cooled in maximum time for maximum
pasteurisation while maintaining thermal control over the PET
container itself.
[0052] The present invention therefore also preferably provides for
pressurisation of the container to provide compensation for any
cooling of heated contents within the container, either before or
after the contents have cooled, and with greater control over the
structure of the container through the critical high heat and high
pressure cycle period within the first few minutes of post
filling.
[0053] With dosages being exactly correlated to the individually
measured requirements of each container, very uniform pressure
ranges may be obtained, as opposed to dosages based on expected
fill levels or after-the-fact average measurements. Therefore,
containers can be down gauged as they will not be required to
accommodate a wide pressure range. Furthermore, the system may
achieve lower spoilage rates due to improperly pressurized
containers because the system immediately self adjusts for fill
variations as containers receive a dosage of liquid or gas.
[0054] Preferably, a container having a seal or cap providing a
temporary seal immediately post-filling and an aperture or opening
being accessible under both ambient or sterile conditions to
provide for the introduction of a medium, heated or sterile, gas or
liquid or both, said aperture or opening also further being
sealable under sterile conditions to provide a controlled raising
of internal pressure within the container following cooling of the
heated contents.
[0055] Preferably, a system and process provides for pressurising
the headspace of a container following the introduction of a heated
or heatable liquid and sealing the container so that the pressure
is retained within the container, and to cool the container
sidewalls to a temperature less than the central core temperature
of the liquid contents.
[0056] Preferably, a sealing device raises the pressure inside a
container prior to sealing, and applies a cooling method to the
container sidewalls for a period of time after sealing until the
temperature of the liquid contents fall below a threshold
value.
[0057] Preferably, this is achieved by means of a device for
sealing and/or capping containers that can also pressurize
containers prior to sealing and/or capping, and that may also
preferably initiate the differential cooling process to prevent the
sidewall temperature exceeding approximately 70.degree. C.
[0058] As the containers exit the capper unit, the differential
temperature regulation must be maintained until pasteurization is
complete within the container, and therefore often through the
typical inversion process of the container and for a set period of
time afterwards. Once the critical time period is reached to deem
pasteurization has been satisfied, then the product temperature may
be more aggressively reduced in order to bring the product
temperature down to below approx. 70.degree. C. Thus, the process
is no longer differential in object, whereby as high an internal
temperature as possible is maintained against a cool outer shell of
container sidewall. The process may be more aggressive in order to
bring the internal temperature down. This period of cooling is the
more traditional approach of relatively unregulated cooling
application and is found in all prior art process. In the present
invention it is preferably mandated to occur, however, until the
core temperature of the product has reached below approximately
70.degree. C. In prior art there is no such mandate and the cooling
is applied as soon as pasteurization is complete and it is applied
until the product is brought down to an exit temperature of
approximately 30.degree. C.
[0059] In the present invention, the cooling may be stopped after
the product has decreased in temperature to approximately
60.degree. C. to 70.degree. C. More traditional cooling may be
applied at any time after this, and could be up to 10 minutes
afterwards in situations where containers are held in collection
bays for example.
[0060] In the present invention the cooling method may be by the
use of any typical medium such as water or air.
[0061] It will be appreciated that in order to maintain as high a
core temperature as possible against a shell temperature below
70.degree. C., then it would be preferable to use a water
temperature below 70.degree. C. The higher the temperature of the
applied medium then the higher the temperature maintenance within
the container until pasteurization is complete. The lower the
temperature application to the sidewalls then the more danger the
internal temperature is reduced too rapidly.
[0062] It will be further appreciated that in order to save energy
cost it is preferable to apply an ambient temperature medium.
Therefore in order to maintain correct internal temperatures the
flow and application rate of the cooling medium must be carefully
controlled to keep internal temperatures high.
[0063] Notwithstanding this, it will be appreciated that should
mediums be applied at more typical cooling temperatures, then these
must be very carefully controlled to maintain correct differential
between the shell temperature and the core temperature.
[0064] Further aspects of the invention which should be considered
in all its novel aspects will become apparent from the following
description.
BRIEF DESCRIPTION OF DRAWINGS
[0065] FIG. 1a: shows a side elevational, diagrammatic view of a
capping and pressure dosing apparatus embodying some of the
principles of one embodiment of the present invention.
[0066] FIG. 1b: shows a plan, diagrammatic view of a capping and
pressure dosing apparatus embodying the principles of part of one
embodiment of the present invention.
[0067] FIG. 2: shows a method according to part of an embodiment of
the invention with a Sealing Unit or Capper capable of pressurizing
the headspace of a container prior to capping or sealing;
[0068] FIGS. 3a-d: show a container and Sealing Chamber according
to part of an embodiment of the invention;
[0069] FIGS. 4:a-d shows a method and Sealing Chamber according to
a further embodiment of the invention with a Sealing Unit or Capper
capable of pressurizing the headspace of a container;
[0070] FIG. 5a-c: show enlarged views of part of one possible
embodiment of the cap of FIGS. 3a-c;
[0071] FIG. 6a-c: show part of one embodiment of enclosing the cap
of FIG. 5 with a pressure application device;
[0072] FIGS. 7a-c: show part of one embodiment of a cap-sealing
device suitable for use in the pressure application device of FIG.
6;
[0073] FIGS. 8a-c: show part of one embodiment of cap-sealing
device of FIG. 7 closing the cap while under compression;
[0074] FIGS. 9a-c: show withdrawal of the cap-sealing device of
FIG. 8 following sealing and subsequent decompression of the
compression chamber;
[0075] FIGS. 10a-c: show the container cap of FIG. 9 following
release from the compression chamber (container not shown
fully);
[0076] FIGS. 10d-f: show a part of a further embodiment of the
container cap of the present invention;
[0077] FIG. 11a-c: show enlarged views of part of a further
embodiment of the cap of FIGS. 3a-b;
[0078] FIG. 11d-f: show enlarged views of a further part embodiment
of the cap of FIGS. 3a-b;
[0079] FIGS. 12a-c: show part of one embodiment of a cap-sealing
device suitable for use in the sterilising application device of
FIG. 11;
[0080] FIGS. 13a-c: show part of one embodiment of cap-sealing
device of FIG. 12 piercing the cap while under sterilisation;
[0081] FIGS. 14a-c: show withdrawal of the piercing and delivery
device of FIG. 13 following sterilisation and subsequent pressure
equalisation of the headspace;
[0082] FIGS. 15a-c: show the resealing of the container cap of FIG.
14 prior to container release from the sterilisation chamber
(container not shown fully);
[0083] FIGS. 16a-c: show additional views of the cap of FIGS. 12,
13, 14, 15 according to one possible method of headspace
modification;
[0084] FIG. 17: shows a method according to a further possible part
embodiment of this invention;
[0085] FIG. 18: shows a further possible part embodiment of the
invention using a sealing chamber;
[0086] FIG. 19a-b: show a possible part embodiment of the invention
in the form of a sealing machine;
[0087] FIG. 20 shows diagrammatically a possible capping
system;
[0088] FIGS. 21a-c; 22a-c; 23a-c; 24a-c; 25a-c; and 26a-c: shows
various possible embodiments with alternative forms of vacuum
compensation;
[0089] FIGS. 27 a-d; and FIGS. 28 a-d: show further alternative
embodiments of the invention using a cold water spray or cold water
bath to cool the containers; and
[0090] FIG. 29 shows a method according to one embodiment of the
invention with a Sealing Unit or Capper capable of pressurizing the
headspace of a container prior to capping or sealing, optional
cooling of the container surface within the Sealing Unit and
following release;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0091] In my further PCT specifications WO 2009/142510 and WO
2011/062512, the contents of which are herein incorporated in their
entirety where appropriate, are described headspace modification
methods and apparatus therefor.
[0092] However, in prior art proposals, in order to pressurize
containers for both cold and hot filled beverage applications,
containers must be conveyed through a nitrogen-dosing unit where
nitrogen may be dripped into the unsealed bottles and shortly
afterwards the bottles are sealed. The following description of
preferred embodiments is merely exemplary in nature, and is in no
way intended to limit the invention or its application or uses.
[0093] While the present invention is capable of various
embodiments, there is shown in the drawings and specification some
presently preferred embodiments, or parts of presently preferred
embodiments, with the understanding that the present disclosures
are to be considered as exemplifications of the invention, and are
not intended to limit the invention to any specific embodiments
illustrated. It will be appreciated that the terms capping and
sealing may be used interchangeably at times.
[0094] With reference to FIGS. 1a-b, a capping and pressure dosing
apparatus 102 is disclosed embodying some of the principles of the
present invention. As will be further described, the present
apparatus includes a rotary capping machine which is configured for
high speed application of closures to associated bottles or like
containers. As will be recognized by those familiar with the art,
this type of machine serially receives filled bottles from an
associated in-feed conveyor or so-called star-wheel, with a machine
being configured to substantially continuously apply threaded
closures to respective ones of the containers as they are moved
through the machine about a generally circular path. The closures
are typically applied by rotation to inter-engage the screw threads
of each closure with its respective container before the container
is moved out of the machine and received by an associated output
conveyor or star-wheel. While such equipment exemplifies the
configuration of the present invention, it is to be understood that
the present capping and pressure dosing apparatus can be configured
to operate in accordance with the principles of the present
invention by use of other, like equipment, including linear or
in-line capping machines.
[0095] The pressure dosing system of the present apparatus may also
be generally configured in accordance with known capping systems,
such as disclosed in U.S. Pat. No. 7,219,480 to Winters et al,
which is incorporated in its entirety by reference.
[0096] In distinction from arrangements known heretofore, the
pressure dosing system of the present system has been
electronically integrated within the capping machine to facilitate
injection of pressure medium into each of the containers being
filled simultaneously with the application of the closure to the
container. In accordance with the present invention, this is
effected by providing the pressure dosing system within a sealing
chamber which is positioned to extend generally over and seal off
the upper neck finish or cap of the filled containers as they are
moved by the capping machine.
[0097] With further reference to FIGS. 1a-b, the present apparatus
includes a capping machine 102, as described above. Capping machine
102 is configured to receive containers 1, such as bottles, from an
infeed conveyor or starwheel 66 along a circular path designated
"infeed" in FIG. 1b, and to deliver the filled and sealed
containers to an output conveyor or starwheel 77 along a circular
path designated "output" in FIG. 1b. The capping machine 102
includes a rotatably driven carrier or turret which rotates around
a centerline (FIG. 1a) and moves the containers 1 along and about a
generally circular path which intersects the circular paths defined
by the input and output starwheels 66 and 77.
[0098] As the containers 1 are moved about the circular path by the
capping machine 102, the closures 80 are applied to a respective
one of the containers. To this end, the capping machine includes a
plurality of capping heads 101. Each of the capping heads 101 is
rotatably driven so that a closure 80 received thereby can be
positioned above a respective one of the containers 1, and the
closure rotated downwardly onto the container into sealing
relationship therewith, closing the container and completing
packaging of its contents.
[0099] As containers 1 are handled by the capping machine 102, the
containers each move along the generally circular path defined by
the capping machine from an input point to an output point. As will
be recognized by those familiar with the art, the input point is
sometimes referred to as the transfer point, that is, the
theoretical point at which filled container 1 is positioned for
receiving a closure thereon.
[0100] In accordance with the present invention, pressure dosing
with any medium, for example compressed air in FIG. 1b, is effected
within a sealing chamber 84 to facilitate consistent dosing of the
containers 1. To this end, the present invention includes a
pressure dosing system within operative association with the
pressure sealing chamber 84, which is integrally connected to the
capping or sealing head of the capping machine 102.
[0101] By this configuration, the pressure sealing chamber is
positioned to dispense medium not only to surround and envelope the
upper end of the container 1 or cap 80, but also downwardly
directly through the open mouth of each of the containers 1
received by the rotary turret of the capping machine 102 just prior
to final application of a closure or seal to each of the containers
by one of the capping heads 101.
[0102] Not only does the present apparatus provide consistent
positioning of the container package for pressurization, the
container is substantially stabilized, reducing or eliminating
further potential for product spillage, allowing for full
pressurization. Additionally, dosing simultaneously with closure
application prevents any pressure dissipation.
[0103] In the preferred form of the present invention, electronic
controls are provided which are operatively connected with the
electronic controls of the capping machine for accurate timing of
the pressure dosing system. The pressure sealing chamber or
pressure delivery mechanism supplying the sealing chamber can be
provided with a suitable fitting which permits a suitable device to
be positioned for controlling and monitoring operation of the
system. By electronically controlling the pressure dosing system,
and coordinating its operation with the capping machine 102, the
present apparatus provides extremely accurate pressure dosing
throughout the entire speed range of the capping machine.
[0104] Referring to FIG. 2, a method of pressurizing containers is
illustrated whereby the sealing unit or capper receives the filled
containers, subsequently seals the headspace from everything but
the internal chamber of a sealing chamber, pressurizes the
headspace within the sealing chamber and therefore the headspace
within the container, and subsequently seals or caps the container
so that a raised pressure exists in the sealed container which is
then ejected from the pressure sealing unit.
[0105] Referring to FIGS. 3a-d, part of an exemplary embodiment of
the present invention is shown with a cap 80 engaged with the
container neck finish 120. According to one aspect of the present
invention a container 1 may enter a capping or sealing station
after being filled with liquid contents such that a headspace
exists above the fluid level 40. The upper neck region of the
container is sealed from the ambient environment by a sealing
chamber 84 that has a sealing surface 841 in contact with the
container. According to the invention, prior to tightening or
applying torque to the cap to seal the headspace finally, a
pressure is applied within the sealing chamber 84 such that the
internal chamber of the container is pressurized, more particularly
the headspace above the liquid is pressurized. Once pressurized the
cap is tightened down by the capping or sealing station such that
the container has a raised internal pressure prior to release from
the unit, as seen in FIG. 3b.
[0106] The sealing mechanism may be of many styles, but there is
distinct advantage in ensuring the size of the pressure sealing
chamber is kept to a minimum. This ensures rapid pressurization of
the chamber in high speed rotary situations.
[0107] In this embodiment it is envisaged that standard caps are
applied to the containers and the pressure capping unit applies
internal pressure to the container prior to applying caps.
[0108] The sealing mechanism may be of any style, for example the
chamber could seal some distance from the neck finish 120 of the
container and down the shoulder region, as illustrated in FIG. 3b,
or more preferably immediately under the neck support ring 33, as
illustrated in FIG. 3c.
[0109] FIG. 3d shows in closer detail one example of a sealing
chamber. The chamber is capable of sealing under the neck support
ring of a container, and prior to applying a cap. The sealing
chamber could be one of many such chambers for example on a rotary
system for torque sealing the cap to the container. Sealing under
the neck provides for multiple changes in container styling without
the need for change parts providing each container has the same
neck finish diameters. Further, by providing for support under the
neck the container may be raised upwardly and supported in the
capper to avoid any top load pressure and to also allow for
multiple bottle heights without the need for change parts also.
[0110] As a further alternative to the present invention, and with
reference to FIG. 4a a method of pressurizing containers is
illustrated whereby the Pressure Sealing Unit receives the filled
containers after the containers have already been through a capping
unit and received a cap. However, in this method the capping unit
has not torqued down the cap, such that the headspace within the
container is not sealed and is still in communication with the
ambient environment through the gap that exists between the cap and
the neck finish threads. The Pressure Sealing Unit subsequently
seals the headspace from everything but the internal chamber of the
sealing chamber, pressurizes the headspace within the sealing
chamber and therefore the headspace within the container, and
subsequently applies torque to the caps on the container in order
to seal off the headspace with a raised pressure existing in the
sealed container, which is then ejected from the pressure sealing
unit.
[0111] With reference to FIGS. 4b-d, the process within the sealing
chamber for the method is shown whereby a typical cap applied by a
standard capping unit but without having been forcibly torqued into
position is shown on the container. The neck finish is enclosed
within the chamber 84 of the pressure sealing unit. Following the
introduction of fluid or gas or medium under pressure, the liquid
or gas is forced into the container through the gap between the cap
and the thread mechanisms of the neck finish, as shown by passage
of liquid 86. Once the desired pressure is obtained, the cap, as
shown in FIG. 4c, can then be torqued into position by advancing
the torque rod 85 within the chamber 84 while holding the container
headspace at pressure. In this embodiment the method may be
achieved using standard caps or modified caps as will be discussed
next. FIG. 4d illustrates removal of the torque rod 85, correctly
torqued cap 80, immediately prior to ejecting the container head
from the chamber 84.
[0112] Typically in prior art, at a bottling plant, containers will
be filled with a hot liquid and then capped before being subjected
to a cold-water spray resulting in the formation of a vacuum within
the container that the container structure needs to be able to cope
with.
[0113] Figures onward from FIG. 3a all refer to upper portions of
containers as similarly shown in FIG. 3a.
[0114] According to a further part aspect of the present invention,
and referring to FIGS. 5 a-c, following the introduction of a
liquid, which may be already heated or suitable for subsequent
heating, a cap may be applied including a small opening or aperture
81. Thus a headspace 23a is contained under the main cap body 80
and above the fluid level 40 in the container. The headspace 23a is
communicating with the outside air at this stage and is therefore
at ambient pressure and allowing for the fluid level 40.
[0115] As seen in FIGS. 6a-c, in part of one embodiment, a sealing
chamber 84 is applied over the neck finish and cap combination to
seal the liquid from the outside air (the upper, closed end of the
structure 84 is not shown). Following the introduction of a
compressive force 50, for example by way of injecting air or some
other gas, the increased pressure within the sealing chamber
provides for a subsequent increase in pressure within the headspace
23b and also forces the fluid level 40 to a lower point due to the
subsequent expansion of the plastic container.
[0116] As an alternative to the injection of gas, a heated liquid
could be injected, for example heated water. This would provide
further advantage, in that the liquid injected would not be subject
to the expansion that would normally occur when injecting gas into
a heated environment. Thus less force would be ultimately applied
to the sidewalls of the container during the early hot-fill
stages.
[0117] Even further, the injected liquid would contract less than a
gas when subsequently cooled. For this reason less liquid is
necessarily required to be injected into the headspace to provide
compensation for the anticipated vacuum forces that would otherwise
occur.
[0118] As a further alternative, steam could also be injected into
the headspace, providing for the increased pressure
environment.
[0119] Now referring to FIGS. 7 a-c (the compressive force not
shown), while pressure is maintained within the sealing chamber 84,
a plug mechanism 82 is moved downwardly from a delivery device 83
towards the aperture 81. It will be appreciated the plug mechanism
could be of many different styles.
[0120] As can be seen in FIGS. 8 a-c, while pressure is maintained
within the sealing chamber 84, the hole is closed off permanently
by the placement of the plug 82 into the hole 81.
[0121] At this point, and as can be seen in FIGS. 9 a-c, the
headspace 23b is charged under a controlled pressure, dependant on
the amount of gas delivered, and the sealing chamber may provide
for withdrawal of the delivery device 83 following a release of
pressure within the chamber as the container is ejected and
returned to the filling line.
[0122] As shown in FIGS. 10 a-c, as the bottle subsequently travels
down the filling line and is cooled, the headspace 23b expands as
the liquid volume shrinks. The fluid level 40 lowers to a new
position 41 and the pressurised headspace 23b expands and loses
some or all of its pressure as it forms a new headspace 23c.
[0123] Importantly, however, once the contents are cooled there is
little or no residual vacuum in the container, or even perhaps a
positive pressure.
[0124] As an alternative, and as shown in FIGS. 10 d-f, the plug 92
may be temporarily attached to the cap, for example by member 91,
during production of the cap. A liquid, as in the example
illustrated, or steam or gas, could be injected in the same manner
under pressure to circumnavigate the plug and enter the container
headspace under pressure, and a rod mechanism 93 is then forced
downwardly to advance the plug 92 into the hole permanently. In
this alternative there is no need to load the rod with multiple
plug mechanisms.
[0125] A further example of such an alternative is provided in FIG.
18. In this part embodiment of the invention the cap 80 has a plug
92 temporarily attached by a member (not shown). A sealing chamber
84 encloses the cap and provides an internal sealed chamber
headspace 87 through the compression of sealing rings 89 against
the upper surface of the cap. Gas or liquid, or a combination of
both, is injected into the chamber headspace 87 through an inlet 86
and through the spaces around the plug into the headspace of the
container. Once the required pressure within the container is
obtained, the push rod 88 is advanced downwardly to force the plug
92 into position within the cap and therefore seal the container
headspace under the required pressure. This provides for a
calculated internal pressure to be achieved precisely at the time
of sealing the container, when the plug is advanced into final
position. This provides for forward compensation of the effects of
subsequent vacuum generated by a cooling of any heated contents
within the container.
[0126] With reference to FIGS. 19a and 19b, the present invention
may be manufactured to function exclusive of cap application and
for final sealing of any temporary cap hole or pathway only. A
typical capping machine head unit 101 encapsulates the sealing
chamber 84 and provides the function of sealing and pressurising
the container through the cap to seal the container. A typical
capping unit may have optionally already torqued the cap into
position, but the container would remain unsealed due to the
presence of a plug, being in an `unplugged` position within the
cap, and allowing the passage of liquid or gas between the inside
and outside of the container. The precise moment of sealing the
container occurs as the plug is rammed into position and the
headspace within the cap is not at ambient pressure, as would be
typical of prior art capping procedures within the filling and
capping area, but instead, with the present invention, a headspace
modification unit 102, which may optionally be of typical rotary
style in mechanics, may receive capped containers 1, and
subsequently pressurise the container immediately prior to sealing
the container with a cap sealing plug.
[0127] It will be appreciated that the present invention offers
multiple choices in carrying out a headspace modification
procedure. Such a piece of machinery could easily be employed to
also provide the function of capping the container in addition to
modifying the headspace during the procedure. Various examples are
disclosed in my further PCT specifications WO 2009/142510 and WO
2011/062512, both of which are incorporated in their entirety by
reference.
[0128] In facilitating the present invention, the complete or
substantial removal of vacuum pressure by displacing the headspace
prior to the liquid contraction now results in being able to remove
a substantial amount of weight from the sidewalls due to the
removal of mechanically distorting forces.
[0129] According to a further part aspect of the present invention,
summarized in FIG. 17, and referring to FIGS. 11a-c, following the
introduction of a liquid, which may be already heated or suitable
for subsequent heating, a cap may be applied including a small
opening or aperture 81 which is temporarily covered by a
communicating seal 91. Thus a headspace 23d is contained under the
main cap body 80 and above the fluid level 40 in the container. The
headspace 23d is not communicating with the outside air at this
stage and is therefore at typical container pressure during the
stages of cooling down on the filling line.
[0130] Alternatively, as seen in FIGS. 11d-f, the opening may be
temporarily covered by a liner seal contained within the underneath
side of the cap and affixed to cover the hole. Construction of the
cap would be virtually the same as any other cap containing an
induction seal or internal liner, except the cap would contain a
small hole that is non-communicating when the liner is in situ.
[0131] As seen in FIGS. 12a-c, and again also referring inclusively
to the example shown in FIGS. 11a-c, once the container has been
typically cooled to a level providing for labelling and
distribution, the headspace 23e will be in an expanded state with a
lowered fluid level, and will have created a vacuum due to the
contraction of the heated liquid within the container.
[0132] As seen in this preferred part embodiment of the present
invention, in order to remove the vacuum pressure a sealing chamber
84 is applied over the neck finish and cap combination to seal the
communicating seal 91 from the outside air (the upper, closed end
of the structure 84 is not shown).
[0133] Following the introduction of a sterilising medium 66, for
example by way of injecting heated water, preferably above 95
degrees C., or a mixture of heated water and steam, or steam
itself, or a mixture of steam and gas, the sterilising medium
provides for the sterilisation of the internal surfaces of the
sealing chamber 84 and the communicating seal 91.
[0134] Now referring to FIGS. 13 a-c, while the sterilising medium
is maintained within the sealing chamber 84, a plug mechanism 82 is
placed downwardly from a delivery device 83 towards the aperture
81. The plug mechanism pierces the communicating seal 91 and is
withdrawn again temporarily as shown in FIGS. 14a-c, providing for
communication between the sterilized volume within the sealing
chamber above the cap 80 and the headspace 23e below the cap. The
container pressure rises and so the fluid level 40 will drop unless
replenished with liquid from the sealing chamber.
[0135] As can be seen in FIGS. 14 a-c, the sterilising medium, for
example heated water at 95.degree. C., is immediately drawn into
the container through the open hole 81 due to the communicating
seal being pierced. This causes equalization of pressure or removal
of vacuum pressure within the container, such that the level of the
headspace 23f rises higher. In another preferred embodiment the
liquid would in fact be injected into the container under a small
pressure supplied from the sealing chamber 84 such that the
pressure within the container would in fact be a positive pressure
and the headspace would in fact be very small.
[0136] The integrity of the product volume within the container is
not compromised as the environment above the cap has been
sterilised prior to communicating with the headspace, and the
additional liquid supplied into the container replaces the volume
`lost` due to shrinkage of heated liquid within the container prior
to the method of headspace replacement described.
[0137] Following the pressure equalization, and now referring to
FIGS. 15 a-c, the delivery device 83 is advanced again such that
the plug 82 will be injected into the hole to close it off
permanently. At this point, the headspace 23f is under a controlled
pressure dependent on the volume of liquid having been delivered to
compensate for previous liquid contraction, as described above.
[0138] The sealing chamber may now provide for withdrawal of the
delivery device 83 which may now be done following a release of
sterilising medium and/or pressure within the chamber as the
container is ejected and returned to the filling line.
[0139] It will be appreciated that many variations of sealing
chamber may be utilised, for example the sealing chamber may only
seal directly to the top surface of the cap, rather than enclosing
the entire cap.
[0140] It will also be appreciated by those skilled in the art that
many forms of seal may be employed to provide the temporary seal
and also the plug mechanism to be utilised.
[0141] Thus a method of compensating vacuum pressure within a
container is described. Referring to FIGS. 16 a-c, the original
headspace level 40, experienced following cooling of heated
contents within a closed container, provides for a vacuum to be
present within the first headspace 23d. Following compensation,
according this embodiment of the present invention, the headspace
level changes and perhaps rises to level 41 depending on the
pressure contained within the headspace, and the pressure within
the headspace 23f is now preferably virtually at ambient pressure,
or preferably slightly positive, such that the sidewalls of the
container are supported by the slight internal pressure.
[0142] This particular part embodiment of the present invention is
summarised in FIG. 17.
[0143] Referring to FIG. 20, a further part embodiment of the
present invention is disclosed. The disclosed integrated system
generally includes an empty container in-feed station prior to the
filling station. This may be through pre-blown containers being fed
into the Filling Enclosure, or may be through on-line blowmolding
production as illustrated. In the case of on-line blowmolding, the
preforms are fed into an integrated blowmolder that also has its
own housing that may be continuously shielded alongside and joining
the Filling and Capping Enclosures.
[0144] The system may also contain a continuous container conveying
system, a container product fill station, a container head-space
dosing station, an optional liquefied gas dispensing station, an
optional gas dispensing station, an optional liquid dispensing
station, a container sealing station, a container internal pressure
sensing station, a discharge conveyor and a reject apparatus.
[0145] Alternatively, as illustrated in FIG. 20, the conveying
system, fill station and container sealing station, or capping
station, may all be integrally contained within an enclosure or
integrated enclosures such that the inside environment may be
pressurised. This will result in the headspace within each
container being pressurised to the desired level as the capper
seals the container. Effectively the ambient pressure within the
enclosure is artificially elevated, while the container is sealed,
and the internal pressure of the container rises immediately upon
ejection of the filled and capped containers as they are presented
to a lower ambient pressure outside of the system enclosures.
[0146] The system provides for the on-line control of the
head-space volume of each container as it is filled with product
through elevated ambient pressure around the container opening. The
head-space volume measurement is precisely controlled at the time
of sealing so that each container corresponds directly to its
individually measured head-space, and generally does not alter once
immediately sealed, except for variations caused by temperature
changes within the contained liquid and ambient temperature or
pressure changes.
[0147] With dosages being exactly correlated to the individually
measured requirements of each container, very uniform pressure
ranges are obtained as opposed to dosages based on expected fill
levels or after-the-fact average measurements. Therefore,
containers can be down gauged as they will not be required to
accommodate a wide pressure range. Furthermore, the system achieves
lower spoilage rates due to improperly pressurized containers
because the system immediately self adjusts for fill
variations.
[0148] A particular advantage of the present method and system is
the greater and more precise control allows for much lower pressure
dosing for hot fill containers. In prior methods a minimum pressure
value can only be assured by over pressurisation on average, such
that the lowest dose achieved will meet specifications. This has
resulted in generally high pressures achieved during the early
stages of hot fill, when the container is hot and malleable. As a
result the container is stressed significantly in most occasions,
necessitating the need for example for petaloid bases and container
designs more suitable to carbonated or pressure vessels. This
reduces significantly the design options available for containers,
and requires additional weight in the container surrounding the
base in order to achieve reasonable results.
[0149] With reference to FIGS. 21a-c, an alternative embodiment of
the present invention also incorporates at least one portion of the
sidewall 801 configured to respond to vacuum pressure forces. In
this particular embodiment, the amount of gas or liquid required to
be forcibly injected into the container 1 within the sealing
chamber 84 prior to sealing the cap 800 onto the container is
reduced.
[0150] When a PET container is filled with liquid at a temperature
above 70 degrees Celsius the plastic walls become very soft and
elastic as the material passes its elastic modulus. With the
subsequent force being applied to the container by introduction of
a force to raise internal pressure, the sidewalls expand and the
overall volume of the container increases. Some of this increase in
volume is non-recoverable and results in the container becoming
larger than originally manufactured. A particular object of the
present invention is to reduce the amount of stress being applied
to the sidewalls to the lowest possible amount to prevent
unnecessary volume growth in the container.
[0151] This is of particular benefit when utilising very thin
sidewalls such as found in lightweight containers. It will be
appreciated therefore, that in a particular volume size container
to be filled with a heated liquid, for example in a range of 75 to
95 degrees Celsius, then the amount of gas or fluid required to be
introduced to compensate for the subsequent contraction of contents
may be reduced if the container has a residual capacity to account
for a portion of the expected contraction. For example, in a
container of 600 cc size, it may be expected that approximately
25-30 cc of fluid contraction may occur and therefore an amount of
gas or fluid equivalent to this would need to be injected into the
headspace during final sealing of the container in order to
compensate. By providing this compensation it may be possible to
therefore lightweight the container or change the shape of the
container as there is a much reduced need for the container to
resist vacuum pressure forces that would otherwise occur.
[0152] It will be appreciated that introduction of this additional
material creates extra stresses initially on the container. By
configuring at least a portion of the sidewall to respond to vacuum
forces, it is possible to reduce the amount of initial material
introduced, for example to 50% of the required amount, if the
sidewalls are able to provide compensation for 50% of the required
amount also.
[0153] It will be appreciated that a container that is only
required to compensate for 50% of expected vacuum pressure through
sidewall compensation will be able to be made more lightweight than
a container required to compensate for the entire 100% through
sidewall compensation.
[0154] With reference to FIGS. 22a-c an alternative embodiment of
the present invention also incorporates at least one transversely
oriented pressure panel 802 in the container 1. In this particular
embodiment the transverse panel is located in the base portion of
the container, but may equally be incorporated in the sidewall. In
this particular embodiment, the amount of gas or liquid required to
be forcibly injected into the container 1 within the sealing
chamber 84 prior to sealing the cap 800 onto the container is also
reduced. As explained above with reference to FIGS. 21a-c, the
transverse panel may account for a portion of the required vacuum
compensation, for example 40%, when moved into the inverted
position as shown in FIG. 22c from the initial position as shown in
FIG. 22a. Inversion of the element 802 may be by way of mechanical
force for example. As the container can account easily for some of
the vacuum compensation required, there is only a need to provide
for approximately 60% of the required liquid contraction by way of
pressure injecting prior to sealing the cap. In this way there is
reduced stress applied to the container during processing.
[0155] With reference to FIGS. 23a-c an alternative embodiment of
the present invention provides for both sidewall vacuum
compensation and transverse panel compensation to be combined with
headspace compensation for even less stress to be applied to the
container during processing. By way of example, it will be
appreciated that if the sidewall compensation elements 801 provide
approximately 30% of vacuum compensation, and the transverse panel
802 is able to provide approximately 40% of vacuum compensation,
then a charge of gas or liquid into the headspace during sealing
would only require approximately 30% of that required in a
container not having vacuum compensation elements equivalent to 801
and 802. It will be appreciated that varying amounts of
compensation may be attributed to each element.
[0156] With reference to FIGS. 24a-c a further alternative
embodiment of the present invention is also provided. In the same
way as already described, at least one portion of the sidewall may
incorporate a vacuum compensation element 803. In this particular
embodiment, the element 803 is also configured to expand radially
outwardly under internal pressure as illustrated in FIG. 24c. It
will be appreciated that under internal pressure charge during
headspace sealing the vacuum compensation element 803 will reduce
the amount of stress within the container by expanding radially
outwardly first. If filled with a heated liquid, the contents will
subsequently cool inside the container and a pressure reduction
will occur. As this happens the element 803 will return to the as
moulded position shown in FIG. 24a and will then subsequently be
able to provide further vacuum compensation. By way of example
only, if element 803 as shown in FIG. 24a is able to provide
approximately 30% of the required vacuum, then 70% of the
compensation would be required to be introduced during headspace
sealing. By incorporating a vacuum compensation element 803 that is
able to expand outwardly then the stress induced is reduced during
the initial phases by a significant amount.
[0157] With reference to FIGS. 25a-c a further alternative
embodiment of the present invention is also provided. It will be
appreciated by the prior descriptions above that a container of the
present invention may be provided with sidewall vacuum compensation
elements or may be provided with sidewall vacuum compensation
elements that are able to expand radially outward under pressure to
reduce stresses during headspace modification and sealing
procedures. These containers may also be provided with transverse
pressure panel compensation elements also to further reduce the
amount of stress required to be imposed on the container during
processing. In this particular embodiment the transverse panel 802
is placed in the base of the container. It is envisaged by way of
example and with reference to FIGS. 24a-c and FIGS. 25a-c, that
element 803 may be able to provide approximately 30% of the
required vacuum compensation and base element 802 may provide
approximately 30% of the required vacuum compensation. Therefore,
40% of the compensation required would be injected into the
headspace during processing as previously described. As sidewall
element 803 is able to expand radially outward then the stress
imposed during processing and headspace modification is reduced
further.
[0158] With reference to FIGS. 26a-c, even further stress reduction
is anticipated in a further embodiment of the present invention. In
a manner as described above, base element 804 is configured to
expand longitudinally outward to relieve the pressure induced
during headspace modification and injection of gas or liquid during
sealing. This reduces the stresses imposed upon the container
sidewall. In this particular embodiment, sidewall element 803 is
also configured to expand radially outward under the internal
pressure. Therefore substantial ability is provided within the
container to reduce the stresses induced as gas or liquid is
injected into the container. Upon subsequent cooling of any heated
contents inside the container both sidewall element 803 and
transverse element 804 are able to be inverted inwardly to assist
vacuum pressure compensation.
[0159] With reference to FIGS. 27 a-d, a further alternative
embodiment of the present invention is provided. A rotary sealing
unit 900 is disclosed that clamps the hot-filled container 1 by the
neck finish and just under the neck support ring 33. As the unit
contains the upper neck thread of the container and prepares to
increase the pressure contained in the pressure chamber 84 of the
sealing unit, and the headspace of the container, the container is
subjected to temperature modification. In this example a cold water
spray 991, typically below ambient temperature and preferably
between approximately 4 degrees C. and 15 degrees C.
[0160] The cold water spray causes the container shell to
immediately fall below the glass transition temperature of the
sidewall material. The temperature within the container does not
fall as rapidly however, and so the liquid contents are able to
subsequently be used to sterilise the internal cap surface when the
container is released from the Pressure Chamber and laid down in a
horizontal position, typically for a period exceeding 30
seconds.
[0161] The container sidewalls are forcibly cooled until the
central core temperature of the container falls below the glass
transition temperature of the sidewalls. The cold spray of this
example is maintained throughout the pressurisation and sealing
period, beyond release from the unit and through the period
immediately subsequent when the container is inverted, as is
typical. The container liquid temperature will fall below the
threshold value required soon after inversion has been completed.
Once this has occurred the container may be returned to the
production line without further cooling prior to entering the main
cooling tunnels typically found some minutes down the production
line.
[0162] As the container has now been `pre-chilled` the efficiency
of the main cooling process is improved also.
[0163] It will be appreciated that many cooling methods may be
employed, for example a cold water bath 992 or the like, as
illustrated in FIGS. 28 a-d, may be used instead of a spray. The
cooling may be directed only at the base region or all over the
container. A cooling jet of air may be used instead of a liquid for
further example. Other cold gases may be used, eg nitrogen, or even
ice may be used in some applications.
[0164] It will be appreciated that by preventing the material of
the sidewalls of the container to be above a certain temperature,
and below the temperature of the liquid contents for a critical
period of time, then the pressure increase induced in the container
will not cause damage to structures that would otherwise occur.
[0165] Preferably the cooling is applied for a period of time
between 1 and 2 minutes, which time allows for the container to be
pressurised, inverted to sterilise the cap underside with still-hot
contents, and for the liquid to fall rapidly to below about 60
degrees C.
[0166] The time required will vary depending on line speed and fill
temperature, however, and the cooling time required may be extended
to over 2 to 4 minutes.
[0167] It is a preferred object of the present invention to provide
a device which enables the pressurisation and sealing of freshly
filled containers after sealing off the upper neck region of the
container, and to initiate the differential cooling process to
prevent the sidewall temperature exceeding approximately 70.degree.
C. and so avoid the deformation of container sidewalls that occurs
through high thermal stresses and high pressure stresses. The
process is summarized with reference to FIG. 29.
[0168] In a preferred embodiment of the present invention, the
bottles must have a retained internal temperature above 80.degree.
C. for up to 30 seconds, and preferably up to 1 minute, more
preferably up to 2 minutes, and occasionally even more preferably
up to 3 minutes. During this time the temperature of the container
body shell must be kept differentially below 70.degree. C. and
preferably below 60.degree. C. for this time. During this period of
time the containers may be inverted or laid horizontally to
sterilize the inside underneath of the cap.
[0169] According to a preferred embodiment, the containers are
rotated through an angle of between 70 degrees and 110 degrees,
more preferably between 80 degrees and 95 degrees, so that they are
transported approximately in a horizontal orientation.
[0170] The temperature of cooling medium and rate of application
must be carefully controlled to provide only for the outside
container surface to be held below 70.degree. C., and so cause the
internal container temperature to be maintained above 70.degree.
C., and more preferably above 80.degree. C., and even more
preferably above 90.degree. C.
[0171] Of course it will be appreciated that if the glass
transition point of an alternative sidewall material is above the
fill temperature then applying a cooling period during sealing or
inversion would not be required.
[0172] Where in the foregoing description, reference has been made
to specific components or integers of the invention having known
equivalents then such equivalents are herein incorporated as if
individually set forth.
[0173] Although this invention has been described by way of example
and with reference to possible embodiments thereof, it is to be
understood that modifications or improvements may be made thereto
without departing from the scope of the invention as defined in the
appended claims.
* * * * *