Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED PACKAGING
5 Backy__und of the Invention
This invention relates to improved packaging
and relates particularly but not exclusively to improved
packaging suitable for the packaging of meats and other
foodstuffs which can deteriorate in air.
10 Description of Prior Art
Hitherto, fresh meat has been packed in
packages which comprise an expanded POLYSTYRENE foam tray
or like plastics foam tray, and a covering of clear
plastics material wrapping such as of P.V.C. or
15 POLYETHYLENE. A problem with such prio~ art packages is
that a purchaser can not inspect the underneath of the
meat because the tray is not transparent.
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It is desirable but not essential to package
fresh meat in packaging where at least two sides of the
meat can be viewed by an intending purchaser. When meat
is packaged, meat juices can be expelled from the meat
5 and can detract from the appearance of the rneat ~hen
viewed from the underside~ Thus if transparent packaging
is envisaged care will have to be exercised in the design
of the packaging to minimise the visual effect of any
such juices which may be expelled from the meat.
In overseas countries, it is common to package
meat products and/or other food products into a tray
which is made from a plastics material which comprises
three layers of the plastics material. The tray is
semi-rigid and is usually composed of layers of P.V.C.
15 and POLYETHYLENE or alternatively P.V.C./P.V.D.C. and
polyethylene. Meat is placed in the tray and then the
tray is packaged with a flushing gas which preferably
comprises 80% 2 and 20~ CO2. The package has a clear
lid which is a co-extruded film of NYLON and S~RLYN
20 (Trade Mark) or a laminated web of POLYESTER, P.V.D.C.
and POLYETH~LENE. The lid material is sealed to the top
edges of the tray and inhibits the escape of the gas from
the package.
In the prior art packaging of fresh meat which
~5 is described above there are particular problems in
adapting it to Australia. Two of the problems are
that:-
ta) The tray is not always transparent and
therefore the contents are not always
viewable.
tb) ~he materials from which the tray ismade are very expensive.
In particular the tray of the prior art packaging i5 not
substantially rigid but only semi-rigid and in order to
35 prevent accidental damage such as by kinking of the tray
which can then cause rupturing of the tray a more rigid
container is required. If the tray or lid is ruptured
the inert flushing gas can escape and then the contents
;~ can be contaminated by the outside atmosphere. The shelf
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life of the packaged products is then substantially
reduced. Because the tray must be made thicker the cost
then becomes prohibitive and further, as the cost of
fresh meat in Australia i5 relatively ine~pensive
5 compared to that in other countries, the cost of such a
tray represents a significant part of the overall cost of
the package and this is commercially undesirable.
Statements of the Invention
Accordinqly it is an object of the present
10 invention to provide improved packaging. Certain
embodiments overcome all the aforementioned problems.
Accordingly one form of the present invention
may provide an improved packaging, particularly but not
exclusively, for fresh meat, comprising a substantially
15 rigid tray of plastics material such as polypro~ylene,
said tray having strengthening formations therein, some
of the formations being on the base of the tray and being
such as to support and space any products therein above
the lowermost portion of said strengthening formations,
20 products in said tray, said tray being enclosed in a
plastics material hermatically sealed closed transparent
outer covering, said covering being such as to
substantially exclude atmosphere from contacting the
products.
Most preferably the products which are packaged
are fresh meat products and the gas is a gas which
maintains the freshness and also the colour of the meat
within the packaging whilst restricting the prolific
growth o bacteria.
The strengthening Pormations are preferably
corrugations in the tray, which apart from providing
strength to the tray also support the products above the
lowermost portions of the strengthening formations.
Thus, the troughs of the corrugations provide channels to
35 assist the draining of any juices from the undersurfaces
of the products. Thus, if the tray is transparent, the
products when viewed from underneath will not be resting
- across the face of a planar bottom of a tray but on the
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crests thereof and thus the juices will not appear to be
clinging to the undersurface of the products and hence
will provide a more attractive appearance to a purchaser.
Preferably the tray is transparent and the
5 bottom of the tray has a gable like contour. This i5
provided to cause any juices which may escape from
products packaged therein, such as fresh meat, to drain
to the lowermost portions of said gable like contour so
as to thereby not greatly inhibit the viewing of the0 contents from the underneath of said tray.
It is also preferred that the plastics material
covering is formed in two parts where one of the parts is
a cup-shaped preform base in which the tray is seated and
the other part is a lid part which is hermatically sealed
15 to the uppermost surfaces of the cup-shaped preform part.
It is also particularly preferred that the tray have gas
passageway means therethrough near the uppermost surfaces
of the side walls thereof so that any gas which is
retained within the packaging volume as defined by the
20 outer covering can pass from the underneath of the gable
like contour of the bottom of the tray to the top of the
tray.
Another form of the invention may provide an
improved packaging method for producing air evacuated and
25 desired gas filled packages, said method comprising:
(a) providing a tray for products to be packaged.
(b) inserting a product into the tray.
(c) placing the tray and package into a sealing
station where the tray and package are fitted
in a depression in a web of outer packaging
material.
(d) introducing a web of further outer packaging
material over the depression to provide a lid
for said depression.
35 (e) closing an air evacuation chamber over the
packaging components in the sealing station.
(f) evacuating air therefrom and allowing air to
evacuate from the tray and the depression.
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(g) allowing a desired gas to pass between the web
and the depression.
(h) sealing the lid to the edge surfaces of the
depression whereby to provide a sealed package
containing a product and the desired gas,
without substantially any air therein.
Brief Description of Drawings
Figure l is a top perspective view of a tray of
the packaging without showing meat therein;
Figure 2 is a close-up plan view of the tray of
Figure l;
Figure 3 is a side sectional view of the tray
shown in Figure 1 taken along line 3-3 of Figure l but
showing the tray enclosed within a plastics material
15 outer covering;
Figure 4 is a schematic block diagram of a
typical packaging installation at a meat processing
plant;
Figure 5 is a schematic side view of a typical
20 packaging machine installation;
Figure 6 is a close-up side cross-sectional
view of a gas flushing and sealing station in the
installation o Figure 5;
Figure 7 is a plan view of the sealing station
25 shown in Figure`6; and ~
Figure 8 is a plan view of a desired gas
introducing means.
Descri~ion of Preferred Embodiments
The packaging (see Figure 3) comprises a two
30 part outer covering l, i.e. a lid 2 and a preform base 4.
The outer covering l is of a transparent plastics
material which will inhibit the escape of desired gas
such as a product preserving and/or colour maintaining
gas from the pac~aging. Suitable gases will be described
35 more fully later. The covering 1 is preferably clear.
The covering l is typically of a thickness of 75 microns
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and is very ~lexible. Typic~l materials from i~hich the
covering 1 can be made are co-extruded films of NYLON and
POLYETHYLENE or polyester, P.V.D.C. and polyethylene.
A very rigid tray 3 is provided to support the
5 meat. The tray 3 is thermo-formed from a preferabl~
transparent and preferably clear plastics material such
as POLYPROPYLENE. Because PO~YPROPYLENE is relatively
inexpensive particularly in Australia, it can be made
relatively thick as in the order of 0.Smm thickness. The
10 cost of the materials for the tray 3 are therefore
insignificant. The tray 3 is made substantially rigid by
having a plurality of strengthening formations in the
form of corrugations 5 therein. The corrugations 5 are
in the bottom of the tray as well as in the side walls of
lS the tray and therefore the tray 3 is extremely rigid and
not likely to be dented and/or creased by dropping the
package which could then cause rupturing of the covering
1 and the contamination of the meat by air which will
then be admitted.
By inspecting Figure 2 it can be seen that the
tray 3 has a bottom 7 and side walls ~. The upper
portions of the side walls 9 in turnr connect with a
peripheral lip 11. The side walls 9 are slightly
outwardly inclined whereby to assist nested stacking of
25 blanks of the trays 3 prior to them being used to form
packages. The bottom 7 of the tray 3 has a somewhat
gable like contour. By inspecting Figure 1 it can be
seen that the gable contour extends across the package
from the left hand side to the right hand side whilst
30 when viewing across the tray 3 in a mutually
perpendicular direction, the tray has a central region
12. Accordingly it can be seen that the contour of the
bottom 7 of the tray 3 is such that the central region 12
is substantially higher than that of the side edges of
35 the bottom of the tray 3 where the bottom 7 terminates
with the side walls 9. It can also be observed that the
corrugations 5 on the bottom 7 will act to support meat
generally above the lowermost portion of the corrugations
5 therein (i.e. the troughs of the corrugations). This
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will support and space meat directly above the bottom 7
and the meat will only contact the actual bottom 7 along
the tops of the corrugations S (i.e. the crests).
Accordingly liquids which escape from the meat drain down
S the inclined surfaces of the contour of the gable shaped
bottom 7 in the troughs of the corrugations to the bottom
side edges of the tray 3. Accordingly, a viewer of the
meat will able to inspect the meat from underneath the
tray through the tray 3 and such viewing will not be
10 greatly impaired by any liquids as the liquids will then
generally be around the periphery of the bottom of the
tray 3.
By inspecting Figure 1 it can be seen that
there are cut-outs 17 in the lip 11 of the tray 3.
15 Apertures 18 are provided in each bot~om corner of the
tray 3. The purpose of the cut-outs 17 and apertures 18
will be explained later in relation to the gas which is
retained within the packaging.
In the particular embodiment herein the base 4
20 of the covering 1 is formed as a generally cup-shaped
preformed depression in a web of covering 1. The cup-
shaped depression has substantially the same dimensions
as that of the tray 3. Accordingly, it can be seen that
the tray 3 can be seated by nesting within the base 4.
25 The base 4 has outwardly inclined side walls 21 which
terminate with an upper horizontally extending lip 23.
The lip 23 extends outwardly away from the lip 11 of the
tray 3 but it is situated close to the outermost portion
of the lip 11. The bottom 25 of the base 4 extends
30 generally horizontally and is planar as distinct from
having a gable like contour.
In order to provide a package, fresh meat is
placed in the tray 3, the tray 3 and the meat are then
placed within the base 4 and the base 4 together with the
35 tray 3 an~ the meat therein are advanced to an assembly
station where the lid 2 comprising a film of covering
material 1 is placed over the top of the base 4. The
peripheral edges of the base 4 are then hermatically
sealed as diagrammatically shown by numeral 31. The
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hermatic sealing is a continuous seal around the lip 23.
This sealing can be performed by way of an impulse
sealing technique o~ by other sealing techniques as will
be explained later. Prior to completely sealing the lid
5 2 of the covering 1 to the base 4, the air within the
tray 3 and the base 4 is flushed by a suitable gas which
will assist in the preserving and colour keeping of the
meat. The flushing process involves evacuation of the
air and its replacement with the desired gas~ A typical
10 gas comprises 80% 2 and 20% CO2. For fresh vegetables
it may comprise 5% 2~ 3~ C2 and 92~ N~. By observing
Figure 3 it can be seen that there are spaces 33 between
the side walls of the base ~ and the side walls 9 of the
tray 3. Similar spaces are provided at the ends of the
15 tray 3~ They have not been shown in the drawings. A
further space 35 is provided underneath the gable like
bottom 7. It can be seen that the space 35 underneath
the tray 3 and the spaces 33 at the side walls of the
tray 3 and the further spaces at the ends of the tray 3
20 may be used to contain some of the volume of th'e gas
which is required to assist in the keeping of the meat.
In this connection it is known that there needs to be
approximately an equal volume of gas to the volume of the
meat. Accordingly with this embodiment, the apertures 17
~5 and 18 in the tray 3 allow the gas from the spaces 33 and
35 to circulate and add with the gas within the tray 3
and therefore represent a total volume of gas larger than
that in the tray 3 alone, which assists in the keeping of
the meat.
~ith the construction,proposed herein the
coveriny material is still a relatively expensive
material but because this is of a very thin nature its
cost is minimized. On the other hand the cost of the
tray 3 is substantially negligible owing to the
35 relatively inexpensive cost of the POLYPROPYLENE
material. Because the tray 3 is substantially rigid it
inhibits rupturing of the covering 1 and therefore a very
desirable packaging for meat is provided. Further, the
gas within the package is under a slight pressure
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relative to atmosphere and hence the covering 1 is bowed
outwardly in a balloon fashion, thereby assisting in
maintaining the covering 1 in substantially non
rupturable condition.
Referring now to Figure 4 there is sh~wn a
block schematic diagram of a typical packaging
installation at a meat processing plant. In the
installation there is provided a boning room 100 and in
that boning room there is a main conveyor 101. The main
10 conveyor 101 extends from a plurality of boning stations
103. Each of the boning stations 103 has secondary
conveyors 105 thereat. In use, boners dissect meat at
the boning stations 103 and place meat into the trays 3
which may be provided in suitable nested stacks at the
15 boning stations 103. The meat packaged in the trays 3 is
then placed onto the secondary conveyors 105 where the
packages are transferred onto the main conveyor 101 and
subsequently discharged from the boning room 100 into a
packaging room 107. In the packaging room 107 there is
20 provided a packaging machine 109.
Referring now to Figure S there is shown a
schematic side view of a typical packaging machine 109 as
shown in Figure 4~ The packaging machine 109 packs two
trays 3 of meat simultaneously i.e. in side by side
25 relation to each other.
In the packaging machine installation shown in
Figure 4, preformed pairs of bases 4 are produced side by
side in a continuous web of material 111 which is wound
on a roll 113. The preform bases 4 are produced at a
30 preform forming station 115. Here, there are dies 117
and 119 which are advanced towards the web 111 to
thermo-form the shape of the preform bases 4 therein.
The dies 117 or 119 may be heated or alternatively the
web 111 may be heated just prior to entering the dies 117
35 and 119~ The preform bases 4 are then advanced to a tray
loading station 121 where trays 3 with meat therein are
delivered from the conveyor 101 to the packaging machine
109 .
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The preform bases ~, the trays 3 and the meat
therein ~re then advanced to a gas flushing and sealing
station 125. At the gas flushing and sealiny station
125, covering material 1 in web form is unwound frorn a
5 pair of side by side rolls (not shown) of covering
material 1 and passed over rollers 129 so that the webs
of covering material 1 lie over the tops of respective
ones of a pair of aligned side by side, open pre~orm
bases 4 with the trays 3 and meat therein.
Gas flushing and sealing then occurs.
The packages are then advanced ~o a guillotine
station 133 where the packages are removed from the web
111 and discharged into a storage area~ ~ guillotine 135
is used to sever the packages across the web 111. A
15 slitting knife, not shown, is used to slit the two side
by side packages from the web 111.
Referring now to Figures 6 and 7 there is shown
a detailed side cross-sectional view of the gas flushing
and hermatic sealing station 125. The gas flushing and
20 hermatic sealing station 125 includes an upper chamber
152 which is in use held stationary and a lower chamber
154. The lower section 154 is arranged for reciprocating
movement on a ram 157. Thus, in use, the lower chamber
154 can be brought upwardly to mate on the undersurfaces
25 of the upper chamber 152 thereby providing a
substantially closed chamber at the gas flushing and
hermatic sealing station 125. The upper chamber 152 has
a platen 159 therein. The platen 159 is fastened to a
further platen 161 with a web of thermally insulating
30 material 163 sandwiched therebetween. The upper platen
161 is fastened to a ra,m 165 which, in turn, is connected
with an air bag 167 which can cause the platens 161 and
159 to move upwardly and downwardly within the upper
chamber 152.
In Figure 6 the platens 161 and 159 are shown
in the downwardly extended position. When the~ are in
the upwardly retracted position, they assume a position
near the upper inside surface 169 of the upper chamber
152. The platens 161 and 159 extend across the width of
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two packages in the packaging machi~e. By inspecting
Figure 6 it can be observed that the platen 159 has
peripheral downwardly protruding sealing edges 171.
These downwardly protruding sealing edges 171 extend
5 around the perimeter of each of the bases 4 of the outer
coverings 1. The lower chambers 154 are divided into two
parts such that the bases 4 and trays 3 which are nested
in the bases 4 can locate in a respective one of the two
parts of the lower chamber 154. This is clearly shown in
10 Figure 7.
The undersurface of the platen 159 is relieved
in the central area thereof and contains an insulation
material 173. The insulation material 173 may be of
asbestos or of other known thermally insulating material.
15 The purpose of the insulating material 173 is to extend
over a major part of the lower surface o~ the platen 159
so that the lid 2 will not touch the undersurface of the
platen 159 except around the peripheral edges 171~ It
will be appreciated that the platen 159 is heated in
20 order to effect hermatic sealing of the lid 2 to the base
4. The heating may be by an impulse heating means or as
shown in the embodiment it may be by passing heated
liquid through passageways 17S therein. Typically the
passageways 175 form a tortuous pass across the platen
25 159 so that it is heated generally uniformly. The heated
liquid is passed to and from the passageways 175 through
vertically rising steel pipes 177 which rise through the
upper platen 161 and through the upper surface of the
upper chamber 152. A gland means 179 is provided on the
30 pipes 177 and on the upper chamber 152 and allows for
reciprocated sliding movement of the pipe 177 as the
platens 159 and 161 are raised and lowered by the ram 165
and also permits an airtight seal with the chamber 152.
Flexible pipes such as hoses 181 can be attached to the
35 tops o~ the pipes 177 to enable the heated liquids to
pass through the passageways 175.
The upper platen 161 is cooled rather than
heated. The purpose of this will be explained in due
course. Here cooling fluids are passed through
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passageways 183 which also form ~ tortuous path across
the upper platen 161. Steel pipes 185 cor~nect with the
passageway means 183 and pass through glands 187 fastened
to the upper chamber 152 and allow for slidiny movement
5 of the pipes 185 therethrough as the platens 161 and 15
are raised and lowered. Hoses 189 can be connected to
the tops of the pipes 185 to allow the cooling fluids to
pass through the pipes 185 and into the passagew~ys 183.
The thermally insulating material 163 is placed
10 between the platens 159 and 161 to thermally isolate each
platen from the other.
A gas flushing member 201 is provided between
the upper and lower chambers 152 and 154. The gas
flushing member 201 is attached to the upper chamber 152.
15 The gas flushing member 201 has two rectangular shaped
openings 203 therein which respectively align with the
two parts of the lower chamber 154 in which the bases 4,
and pre~orms 3 are located. The gas flushing member 201
is typically of metal such as brass.
It can be seen that the covering material 1
which is used to provide the lids 2 of the packages
passes through the respecti~e openings 203. Accordingly
the webs 1 pass around the roller 129 across the top of
the gas flushing member 201 and through the openings 203
25 and then across the undersurface of the gas flushing
member 201 at the other side of the gas flushing member
201 to which the roller 129 is positioned.
The gas flushing member 201 has central
passageway means 207 therein which communicate with each
30 of the openings 203. It can be seen that the passageways
207 terminate with the openings 203 midway between the
thickness of the gas flushing member 201 where it passes
underneath the upper chamber 152. A small space 209 is
provided between the gas flushing member 201 and the
35 lower edge surface of the upper chamber 152 where the
covering material 1 passes from the top of the gas
flushing member 201 through the openings 203. This is
clearly shown in Figure 6.
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The upper surface of the lower chamber 154 i5
provided with a neoprene sheet 211 which surrounds the
two parts in the lower chamber 154 in which the bases 4
and the trays 3 are received. 'rhe neoprene sheet 211 is
5 provided to effect substantial atmosphere sealing of the
chamhers 152 and 154 when those chambers are brought
together to define a closed gas flushing and hermatic
sealing station 125. It is noted, however, that there is
not complete sealing because there is a small space
10 provided by the opening 209 where the covering material 1
passes into the gas flushing and hermatic sealing station
125.
The platen 161 carries two spring loaded
pushing knife like members 213. The knives 213 extend
15 across the width of a respective one of the two parts of
the lower chamber 154 in which the bases 4 and trays 3
are received. The knives 213 each comprise a bar like
metal member which is attached to the upper platen 161.
The attachment is by way of four screws 215 which pass
20 into the side of the upper platen 161 which is adjacent
the outlet of the passages 207 in the gas flushing member
201. The screws 215 each have their heads located in
respective elongate slots 217, such that the knives 213
can move upwardly and downwardly at the side edge of the
25 platens 161 and 159. A planar bearing material 221 is
provided between the knives 213 and the side edge of the
upper platen 161. The bearing material 221 allows for
relatively easy sliding movement of the knives 213 in the
up and down direction.
The knives 213 are connected at their upper
edge surfaces with four push rods 225 which, in turn, are
slidably received within respective tubular members 227.
Each tubular member 227 is threaded on its external
surfaces and is screw threaded in a suitable aperture in
35 the upper surface of the upper chamber 152. Thus, the
tubular member 227 can be extended or retracted into the
aperture. A compression spring 229 is fitted within the
tubular member 227 and by appropriate screw adjustment of
the screw member 227 desired pressure can be applied from
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the spring 229 to the top of the push rods 225 to, in
turn, bias the knives 213 to the ~ownwardly extended
position. A suitable respective lock nut- 231 holds the
tubular threaded member in the desired adjusted position.
5 The push rods 225 and tubular members 227 are positioned
uniformly spaced apart along the length of the knives 213
so that the knives 213 are urged downwardly substantially
uniformly along their length.
When the platens 161 and 159 are raised the
10 push rods 225 compress the springs 229. When the platens
161 and lS9 are extended downwardly to the position shown
in Figure 6, the springs 229 maintain the knives 213
extended downwardly below the lower surface of the
downwardly extending sealing edges 171 of the platen 159
lS so that the lowermost edge of the knives 213 contacts the
web 1 and pushes the web 1 downwardly onto the upper
surface of the neoprene sheet 211. This is provided to
inhibit the web of material 1 from contacting the heated
lower platen 159 until the web 1 is brought down to
20 engage the peripheral lip of the base 4.
Because the upper platen 161 is cooled, knives
213 are cooled - i.e. they are at a lower temperature
than that of the heated platen lS9. Thus, the lowermost
edge of the knives 213 do not effect any heat sealing of
25 the upper web 1 to the peripheral lip of the base 4.
Air evacuation openings 233 are provided in the
upper and lower chambers 152 and 154~ In use air is
evacuated from these openings when the upper and lower
chambers 152 and 154 are closed and prior to insertion of
30 gas through the gas flushing member 201.
The sequence of operation of the gas flushing
and sealing station 125 is as follows. When the bases 4,
complete with trays 3 and with meat therein are indexed
into the gas flushing and sealing station 125 they locate
35 directly above the two parts in the lower chamber 154.
In this position the lower chamber 154 is retracted to
allow the bases 4 and trays 3 and meat to index into this
position. The lower chamber 154 is then closed by
- extending ram 157. The platens 161 and 159 are retracted
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at this stage. Air is evacuated through the air
evacuation openinys 233 in both the upper and lower
chambers 152 and 154. After the air i5 being ev~cuated,
gas is introduced via the gas flushing member 201 so that
5 it leaves the passageway means 207 and passes into the
bases 4 and trays 3 between the upper lip of the bases 4
and the webs of material 1. Thus, air which is exhausted
through the air evacuation openings 233 is replaced by a
gas such as 80% 2 and 20% C02. After a sufficient time
10 to allow for the base 4 and tray 3 to be filled with this
gas, the platens 161 and lS9 are lowered. The lowermost
surface of the blade 213 then contacts the upper surface
of the material 1 of the lid 2 and causes it to engage
with the upper surface of the lip of the base 4 on the
15 neoprene sheet 211. The gas supply to the gas passages
207 is then stopped. Continued downward movement of the
platens 161 and 159 causes the lower platen 159 to engage
with the upper surface of the material 1 of the lid ~ and
to effect hermatic heat sealing of the lid 2 to the base
20 4. Thus the gas is hermatically sealed within the
package. The platens 161 and 159 are then retracted and
the lower chamber 154 is also retracted. The package is
then indexed out of the gas flushing and sealing station
125. In this condition, the package is integrally
25 connected with the web of material 111 from which the
bases 4 are made.
After the packages are indexed out of the gas
flushing and sealing station 125, they pass into the
separating station 133 where the packages are separated
30 from the web of material from which the bases 4 are made
by the knife 135 and by a slitting knife (not shown).
Appropriate hydraulic and/or pneumatic
circuitry and appropriate electronic circuitry is
provided to effect the necessary indexing and operation
35 of various rams and knifes and operation of air
evacuation and gas flushing. The design of these items
is considered within the skill of any addressee familiar
32
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with the art of packaging machines generally.
Accordingly it has not been ~isclosed herein as it does
not form any part of the inventive concepts.
The packages 50 produced will provide ~or a
5 generally long shelf life of the packaged meat.
It should also be appreciated that because the
gas which is trapped within the base 4 and the lid 2 is
totally available for circulating within the package by
reason of the openings 17 in the peripheral lip of the
lO tray 3 and by reason of the openings 18 in the bottom
corners of the tray 3, that a relatively smaller pack can
be provided than with other types of packages where for
example there is no circulation of gas which may be
trapped in the spaces 33 and 35 between the tray 3 and
lS the base 4. Thus, substantially more product can be
packed in any given space. Desirably the packs are made
suf~iciently large as to accommodate desired weights of
meat.
It should be appreciated that because the gas
20 which is introduced into the package 1 is under a slight
pressure relative to atmosphere, that the package l is
initially inflated somewhat and bows slightly outwardly.
This enables the package to have a substantially
outwardly directed force supplied to the packagin~
25 materials of the lid l and the base 4 and this generally
inhibits easy rupturing of the lid 2 or the base 4
material. It should also be appreciated that the tray 3
is not attached in any way to the lid 2 or the base 4.
It merely rests between the lid 2 and the base 4.
The openings 18 in the bottom corners of the
trays 3 also allow the trays 3 to easily drop into the
bases 4, as such openings allow air under the trays 3 to
readily escape during the insertion process. It has been
found that if the openings are not present then the air
35 trapped between the trays 3 and the bases 4 can cause
upwardly directed forces to be applied to the trays 3
during the insertion process and such forces can cause
the trays 3 to skew slightly within the bases and
completely upset the operation of the packaging machine.
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If the packaging is to contain fresh vegetables
it is desirable that the outer covering, i.e. the lid 2
and the preform base 4, be of a material that will allow
any CO2 which may generate within the package to escape
5 and allow 2 to permeate into the package to replace the
C2 which escapes. Accordingly, it is desirable for the
outer covering material to be made of polyethylene or
like plastics material which will permit this to occur.
It should also be appreciated, that some
10 products to be packagedl such as fish or poultry, will
absorb CO2 from the gas after packaging. ~7ith the
present apparatus and paekaging, it is possible to over
inflate the package to a desired amount initially, so
that when the CO2 is absorbed, the final volume of the
15 package will be the required volume. If the outer
packaging material has NYLON as one of the web materials,
then NYLON has a memory f and thus the natural shrinkage
whieh oeeurs beeause of this memory when the outer
packaging material reduees in volume beeause of the
20 absorbtion of some of the gas into the produet, ean be
equated to this memory shrinkage so that the outer
packaging material will not be slaek or even worse,
shrunk to a degree that eollapses and ruptures the
paekage. This permits the outer paekaging to be in a
25 condition which inhibits total eollapse or rupturing
whieh may otherwise oeeur if it were not compensated for.
Thus/ with the present paekaging it ean eontain 100% CO2
if desired without any real paekaging problems oeeuring.
