U.S. patent number 3,928,938 [Application Number 05/480,907] was granted by the patent office on 1975-12-30 for method for evacuating packages.
This patent grant is currently assigned to W. R. Grace & Co.. Invention is credited to William E. Burrell.
United States Patent |
3,928,938 |
Burrell |
* December 30, 1975 |
Method for evacuating packages
Abstract
A filled flexible receptacle such as a thermoplastic bag
containing a food product is evacuated by placing the filled
portion of the bag in a first vacuum chamber; extending the neck of
the bag into a second and adjacent chamber; evacuating the first
chamber thereby causing the bag to balloon outwardly away from the
product; and, while the first chamber is being evacuated,
evacuating the second chamber and, consequently, evacuating the
interior of the ballooned bag; thereafter, when evacuation of the
bag is complete, elevating the pressure in the first chamber to
collapse the bag firmly around the product and immediately closing
the bag thereby making an evacuated package.
Inventors: |
Burrell; William E. (Duncan,
SC) |
Assignee: |
W. R. Grace & Co. (Duncan,
SC)
|
[*] Notice: |
The portion of the term of this patent
subsequent to September 3, 1991 has been disclaimed. |
Family
ID: |
27007001 |
Appl.
No.: |
05/480,907 |
Filed: |
June 19, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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375300 |
Jun 29, 1973 |
|
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Current U.S.
Class: |
53/434;
53/417 |
Current CPC
Class: |
B65B
31/024 (20130101) |
Current International
Class: |
B65B
31/02 (20060101); B65B 031/02 () |
Field of
Search: |
;53/22B,86,112B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGehee; Travis S.
Attorney, Agent or Firm: Toney; John J. Lee, Jr.; William D.
Jackson; Richard G.
Parent Case Text
This is a continuation of application Ser. No. 375,300 filed June
29, 1973.
Claims
I claim:
1. In the process of evacuating filled thermoplastic bags, pouches,
and the like, the improvement which comprises:
a. providing adjacent first and second vacuum chambers with an
aperture connecting said chambers;
b. placing the filled portion of the bag in the first vacuum
chamber,
c. extending the neck of the bag into the second and adjacent
vacuum chamber, said bag neck passing through said aperture whereby
the mouth of said bag is unrestrained and open within the second
chamber,
d. evacuating the first chamber; and, subsequently,
e. evacuating the second chamber at a more rapid rate than said
first chamber is evacuated, thereby evacuating said bag,
f. stopping the evacuation of the said chambers when the evacuation
of the second is completed,
g. closing and sealing said bag; and,
h. removing said sealed bag from said first chamber.
2. The process of claim 1 wherein said sealed bag is removed from
said first chamber and delivered to a conveying means.
3. A process of evacuating and closing flexible, impervious
receptacles such as pouches, bags and the like which have at least
one opening and contain at least one product comprising the steps
of:
a. confining the product containing portion of said receptacle
within a first region;
b. confining a portion of the receptacle which contains said
opening in a second region so that the interior of said receptacle
is in communication with said second region through said
opening;
c. reducing the pressure within said first region thereby causing
at least a part of said receptacle to move outwadly away from
contact with said product; and, subsequently,
d. reducing the pressure within said second region to evacuate the
interior of said receptacle so that the receptacle again contacts
the product; and,
e. closing said opening thereby making an evacuated, sealed,
package.
Description
FIELD OF THE INVENTION
This invention relates to a method and apparatus for evacuating
receptacles, especially impervious, flexible receptacles such as
thermoplastic bags and pouches. The invention has particular
application in the vacuum packaging of fresh and frozen food
products such as beef, poultry, ham, cheese, etc.
BACKGROUND OF THE INVENTION
A number of methods are available in the prior art for packaging
food products such as meat and poultry in flexible containers such
as thermoplastic packages and bags. In some processes the product
is placed in a bag, a vacuumizing nozzle is then inserted into the
bag, the mouth of the bag is gathered around the nozzle while the
vacuum acting through the nozzle withdraws the air from the bag,
and after evacuation is completed the bag is either clamped shut
with a metal clip or heated welded shut. In this method complete
evacuation of the bag is difficult to obtain because the meat
product is usually damp and tends to cling to the bag wall so that
surface crevices in the meat will form a pocket with the bag wall
which blocks the passage of air out of the bag during the
vacuumizing process. Accordingly, it is one object of the present
invention to provide a method and apparatus for satisfactorily
evacuating bags filled with meat products and the like.
Rather than insert a nozzle into a filled, impervious pouch or bag,
other prior art methods employ a vacuum chamber into which a filled
bag is placed in open condition. Subsequent evacuation of the
chamber also evacuates the bag; and, before the chamber is opened,
the bag is sealed or closed within the chamber. An apparatus for
carrying out such a process is disclosed in U.S. Pat. No. 2,790,284
issued on Apr. 30, 1957 to P. B. Hultkrans. However, the
immediately foregoing method still does not solve the problem of
evacuation of a bag filled with a crevice containing product such
as meat or poultry. Accordingly, it is another object of the
present invention to provide a method and apparatus whereby a
package filled with a product which tends to cling to the package
wall may be evacuated and closed within a vacuum chamber.
Another prior art method and apparatus for evacuating a filled bag
within a vacuum chamber is disclosed in U.S. Pat. No. 3,714,754
issued on Feb. 6, 1973 to Edward L. Holcombe et al. In the Holcombe
et al. patent, the bag loaded with a product is placed in a vacuum
chamber and the neck of the bag is clamped over an extractor which
can withdraw vacuum from the bag independently of the vacuum
applied within the chamber. However, this method requires the
manual locating of the bag neck around the extractor tube and the
manual clamping of the bag neck thereto. Accordingly, it is another
object of the present invention to provide an independent means for
evacuating a bag within a vacuum chamber which requires a minimum
of manual handling and locating of the bag within the vacuum
chamber.
The foregoing and other objects are achieved by the process and
apparatus described below.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a process of evacuating
filled receptacles such as thermoplastic bags, pouches, and the
like by placing the filled portion of the bag in a first vacuum
chamber, extending the neck of the bag into a second and adjacent
vacuum chamber, evacuating the first chamber thereby causing the
bag to balloon outwardly away from the product; and, while said
first chamber is being evacuated, evacuating the second chamber
and, consequently, evacuating the interior of the balloned bag;
thereafter when evacuation of the bag is complete, elevating the
pressure in the first chamber to collapse the bag firmly around the
product and immediately closing the bag thereby making an evacuated
package.
In another aspect, the present invention is a process of evacuating
and closing flexible, impervious receptacles such as pouches, bags,
and the like which have at least one opening and contain at least
one product, the process comprising the steps of confining the
product containing a portion of the receptacle within a first
region, confining a portion of the receptacle which contains the
opening in a second region so that the interior of said receptacle
is in communication with the second region through said opening of
the receptacle, reducing the pressure within said first region and,
subsequently, reducing the pressure within said second region so
that the interior of the receptacle is evacuated, elevating the
pressure in the first region, and, thereafter, closing the opening
to make an evacuated package.
In still another aspect, the present invention is an apparatus for
evacuating and closing flexible, impervious receptacles such as
pouches, bags, and the like which have at least one opening and
contain at least one product and the apparatus comprises a first
vacuum chamber with a second vacuum chamber adjacent to it and an
aperture connecting the two chambers for passing the portion of the
receptacle containing an opening therethrough. Means to evacuate
the first and second chambers and means to close the package when
its evacuation is completed are included in the apparatus. Also,
the closing means for the apparatus may be either a clip applying
device or a heat seal apparatus located within one of the vacuum
chambers.
The invention may be better understood by reference to the drawings
described below and the following Description of the Preferred
Embodiment.
DESCRIPTION OF THE DRAWINGS
In the drawings which are appended hereto and made a part of this
disclosure;
FIG. 1 is a side elevational representation of a preferred
apparatus according to the present invention in which the vacuum
chambers of the apparatus are closed and a chamber wall is removed
to show the interior arrangement;
FIG. 2 is a top plan view of the apparatus shown in FIG. 1 with
both of said vacuum chambers open;
FIG. 3 is an isometric representation of a section of the lower
portion of both of said vacuum chambers showing a filled package
ready to be evacuated;
FIG. 4 is a representation in partial section showing the gathering
arms of the preferred closing means of the preferred apparatus;
FIG. 5 shows in partial section a clip being applied to a bag neck
which has been gathered by the gathering arms shown in FIG. 4;
FIG. 6 shows the clip of FIG. 5 being closed around the gathered
bag neck as the clip is forced into the clip anvil;
FIG. 7 is a sectional schematic side representation of the base of
the vacuum chambers of the preferred embodiment showing the clip
magazine and the clip punch and driving wheel; and,
FIG. 8 is a front elevational representation of the drive and
timing wheel shown in FIG. 7.
DEFINITIONS
As used herein, the terms listed below will be understood to have
the meaning set forth beside each term:
"Receptacle" means any container for receiving an article or
product to be packaged in the receptacle and includes bags and
pouches.
"Bag" means a receptacle or container constructed from tubular
stock by sealing one end of the tube. A bag may be pleated or
gusseted.
"Pouch" means a receptacle or container constructed from sheet
stock. A single or multiple sheets may be used; and, commonly a
pouch may be made by folding a single sheet and sealing the free
edges of the sheet together.
"Aperture" means a hole in a wall that may be of any shape and
includes slot, oval, circular, rectangular, and irregular shaped
holes. An aperture may be formed by joining two wall sections that
have indentations in one or both of the surfaces so joined.
"Vacuum" means a pressure level lower than atmospheric pressure and
may be expressed in lbs./sq.in. or in inches of Hg. A "high" vacuum
means a very low pressure level.
"Heat shrinkable" means that the particular material referred to
will shrink upon the application of heat.
"Heat sealable" means that the particular material referred to can
be welded to itself under the influence of temperature and
pressure.
"Opening" in a receptacle means a passageway from the exterior of
the receptacle to the interior; and, in the case of a bag, the
"opening" can be the bag's mouth and the part of the bag containing
the "opening" would be the bag's neck.
PREFERRED EMBODIMENT
In FIG. 1, a double chamber vacuumizing apparatus 1 is shown in a
side elevational representation with the side wall of the apparatus
cut away so that the interior arrangement may be clearly seen.
Also, reference will be made to FIG. 2 which is a top plan view of
the apparatus of FIG. 1 with the hinged cover or head 3 being open.
The cover 3 is hinged to base member 2 which is divided by lower
chamber divider wall 12 which cooperates with the upper divider
wall 11 to separate apparatus 1 into the two chambers or regions 4
and 5. The first and larger region or chamber 4 is the product
chamber in which the portion of a bag or receptacle 9 containing a
product 8 is placed on product conveyor 14. The receptacle opening
or bag neck is extended into the second and smaller region 5 which
serves as the receptacle or bag evacuation chamber. The second
chamber 5 is evacuated through vacuum port 7 and the first chamber
4 is evacuated through vacuum port 6.
Looking now at FIG. 3, the extension of the neck of bag 9 from the
first chamber 4 into the second chamber 5 can be more clearly seen.
The operator of the apparatus 1 receives the bag 9 filled with a
product 8 and places the bag on the conveyor 14 and brings the neck
of the bag down through the bag neck guide 13 and extends the neck
of the bag across walls 18a and 18b of the gathering arm track 18,
across plunger housing 21, cutter housing 22, and the recess 12a in
wall 12 so that the opening 9b of the package is located in the
second region or chamber 5 just above the evacuation port 7. The
recess 12a in the wall 12 forms the lower half of the aperture in
the wall which divides chambers 4 and 5 and this aperture and wall
is completed when the cover 3 is rotated into the position shown in
FIG. 1 so that a corresponding recess in wall 11 forms the upper
half of the divider wall aperture.
Once the chamber is closed evacuation of chamber 4 begins through
vacuum port 6. Any conventional vacuum pump which is well known in
the art may be used and be connected to vacuum port 6 to evacuate
chamber 4. As vacuum is applied the chamber will be evacuated very
rapidly, in the order of two to three seconds to a low level of
pressure or around 27 inches of Hg. and further reduction in
pressure takes a significantly longer period of time. The bag neck
sufficiently fills the aperture between chambers 4 and 5 so that
very little air is leaked from the second region 5 into the first
region 4 during this phase of evacuation. In this initial phase,
the bag 9 will balloon outwardly as shown by dotted lines 10
because of the difference in pressure between the interior of the
bag 9 and the chamber 4. This outward expansion or balooning of the
bag also occurs in the bag's neck region and the expanded neck
further seals the aperture between chambers 4 and 5. While the bag
is ballooned into shape 10, evacuation of the second region or
chamber 5 is begun. This will usually be of the order of 1/2 sec.
after the beginning of the evacuation of chamber 4. Chiefly because
of its smaller size, the evacuation of the second chamber 5
proceeds at a more rapid rate than that of first chamber 4 and
overtakes the vacuum level in first chamber 4 thus causing the
ballooned bag 10 to begin to collapse back onto product 8. The
second chamber 5 will reach a vacuum level of 28 inches of Hg. or
lower depending on the period of time vacuum is supplied through
port 7. As the vacuum level in the second chamber 5 is reduced
below that in chamber 4 and the bag 9 begins to collapse back upon
the product 8, atmospheric pressure is restored in chamber 4 by
stopping the vacuum pumping action through port 6 and venting the
chamber to the atmosphere by valve means which are not shown. This
sudden increase in the pressure differential between the inside and
outside of the bag will cause the bag to collapse rather rapidly
and suddenly driving out any remaining air. Immediately as this
takes place, the bag is clipped and closed as will be described
more fully hereinafter.
Once the bag is clipped and closed, the excess bag neck material is
trimmed off and the head or cover 3 is opened and conveyor 14 will
start up and deliver the sealed bag to conveyor 16 while the
operator is preparing to place another filled bag within apparatus
1 to begin the process again.
When, as described above, the bag balloons outwardly to the shape
10 the bag wall is separated from the product 8 and any crevices or
cavities in the product are exposed to the space which now exists
between product 8 and the expanded bag wall 10. Thus, when
evacuation of the second chamber 5 begins, a continuous passageway
exists whereby a substantial portion of the surface of the product
8 is brought directly under the influence of the vacuum being drawn
through second chamber 5.
A preferred package or bag closing and sealing means is illustrated
in FIGS. 3 - 7. FIG. 4 is a view in partial section looking along
the direction of lines 4--4 of FIG. 3. This view is from between
walls 18a and 18b of the lower gathering arm guide track 18 and
between walls 17a and 17b of the upper gathering arm track 17. In
FIG. 4 bag neck 9a is shown partially compressed between the bag
neck guide 13 and walls 17a and 18a. Gathering arms 25 move
inwardly towards each other to further compress the bag neck 8 into
the shape shown in FIG. 5. As the gathering arms 25 have moved more
closely together to wedge the bag neck 9a into a smaller space,
plunger 24 drives clip 37 up around the gathered bag neck 9a and
forces the clip towards anvil 19. Further motion of the plunger
forces the clip into the anvil 19 and bends it into the shape shown
in FIG. 6 securely around the bag neck 19 thereby closing and
sealing same. As this is completed cutter arm 26 with serrated
cutter blade 27 is driven upwardly to cut off the excess bag
material which extends beyond clip 37. The clip 37 is taken from
the group of clips 33 contained in clip magazine 32 shown in FIG.
7. The clips 33 are urged forward in the magazine 32 under the
influence of clip spring 34 and are delivered to plunger 24
immediately below plunger housing 21. Plunger 24 is connected to
plunger crank arm 29 at pivot 30, and crank arm 29 is driven by
timing wheel 28 to which it is connected by crank pin 35.
Cutter arm 26 is driven upwardly through cutter housing 22 to sever
the excess bag neck material and the drive means for cutter arm 26
is not shown but may be a pneumatically operated cylinder or an
electrically driven solenoid, both of which drive means are well
known in the art.
An alternate method and means for closing a package or bag after
evacuation is to remove the bag neck guide 13 shown in FIG. 3 and
widen the aperture opening 12a to correspond to the width of the
flattened bag neck. The clip applying means may be eliminated in
this alternate closure means and a sealing bar may be substituted
for the blade 27 with the sealing bar being the same width as the
aperture 12a. Bar 27 may be electrically resistance heated and a
pressure backing member may be substituted for the cutter track 38
as shown in FIG. 6 so that when the arm 26 is driven upwardly after
the evacuation of the bag the heated bar 27 will contact the
flattened bag neck 9a and press same against the pressure backing
member 38. The bar would dwell sufficiently long in its position of
pressing the bag neck against the backing member 38 until the bag
is sealed to itself. Of course, for this alternate method and means
to be employed the bag material must be of a type that will weld to
itself under the influence of heat and the thermoplastic materials
such as polyethylene, ethylene vinyl acetate copolymers, saran, and
the like with the appropriate coatings and surface treatments are
suitable for this purpose.
FIG. 8 is a frontal view of the plunger drive wheel 28 which is
driven by pinion 36 which, in turn, is driven by a conventional
electrical motor which is not shown. Crank pin 35 is connected to
plunger crank 29 and at the beginning of each cycle crank pin 35 is
at bottom dead center of the wheel. The time represented by t.sub.1
is the time from the beginning of the clip's engagement with the
anvil to the end of the engagement as the plunger withdraws.
Referring also to FIG. 7, timing cams may be placed on shaft 31 on
which wheel 28 is mounted and these cams can be used to control
such functions as the venting of the chambers to atmosphere as the
clipping and cutting cycle is completed.
Referring now to FIGS. 1 - 8, a semi-automatic operation of the
foregoing described apparatus according to the process of the
present invention will be described. In the following description
valves, cams, a timer, vacuum pump, pressure sensor, etc. are
mentioned. None of these are shown in the drawings and each is a
conventional item whose use and application is familiar to those
skilled in the packaging machinery arts. The packaging cycle begins
when the operator manually places a filled bag into first chamber 4
and extends the neck into second chamber 5. The operator then
closes the chambers with cover 3 and the closing actuates a
microswitch which starts a timer and opens the valve to port 6 so
that a vacuum pump can evacuate chamber 4. At a predetermined time,
preferably of the order of 1/2 or 5/8 of a second after the
evacuation of the first chamber has begun depending on the size of
the chamber and power of the vacuum pump, the evacuation of the
second chamber is started by the timer opening the valve connecting
port 7 with the vacuum pump. During this time ballooning of the bag
9 to shape 10 will have occurred. When the pressure in the first
chamber reaches a preset level, preferably about 26 or 27 in. Hg.,
a pressure sensor in the first chamber shuts off the vacuum in the
first chamber and simultaneously sends a signal through a delay
timer to the electric drive motor for pinion 36. At this point, the
timing and drive wheel 28 is at the position shown in FIG. 8 with
the crank pin at bottom dead center. The timed signal can be preset
for any given duration and is preferably about 11/2 seconds which
means that wheel 28 will start to make one complete revolution at
the end of that preset period of time. Timing cams are located on
the supporting shaft or axle 31 of wheel 28 and as wheel 28 rotates
in a counterclockwise manner (FIG. 8) one of the cams will actuate
a valve causing the first chamber to vent to atmosphere prior to
reaching time span t.sub.1. Venting the first chamber to atmosphere
causes the bag 9 to collapse or, rather, be violently pushed
against the product since the bag interior is at the pressure level
of the second chamber which now will have reached lower than 28 in.
Hg. This violent collapsing of the bag drives out any residual air
in the bag immediately before the gathering and clipping cycle
begins with time span t.sub.1. During t.sub.1, the bag neck is
gathered and the clipper plunger 24 drives clip 37 into position
around the gathered bag to seal and close same. Following
withdrawal of the plunger and trimming of the bag neck at the end
of t.sub.1, a second cam shuts off the vacuum to the second chamber
and vents that chamber to the atmosphere. The cover 3 may now be
raised and while the operator is getting another filled bag ready,
conveyor 14 moves the completed package to exit conveyor 16.
It is to be understood that the present invention is not limited to
bags and pouches but can be applied generally to any receptacle
whose walls will flex outwardly under the influence of a pressure
differential and will conform to a wall aperture. Furthermore, as
set forth above, the shape of the wall aperture may be made to
conform to the shape of the receptacle opening and to the closing
and sealing method desired.
One particularly desirable package results from the process and
apparatus of this invention when a meat or poultry product is
enclosed in a heat shrinkable, essentially gas impervious,
thermoplastic bag. After the meat product has been sealed in the
bag and the resulting package conveyed out of the apparatus, the
package is passed through either a hot water bath or through a hot
air tunnel to shrink and further tighten the bag material around
the product. The tight grip of the shrunken material protects the
product from pinhole leakage because the material is so firmly
pressed against the product that even when a hole or cut occurs the
hole is essentially sealed by the adjacent or exposed portion of
the product so that no air can enter the package.
* * * * *