Note: Descriptions are shown in the official language in which they were submitted.
' 11~6Z599
Background of the Invention
(1) Field of the Invention
The field of art to which this invention pertains
is package-making and, more particularly, it is directed
to vacuum skin-packaging.
More specifically, this invention relates to a
method of and apparatus for packaging a product, such as a
piece of meat, in thermoplastic film. In such method, an
upper thermoplastic film is moved downwardly by means of a
vacuum chamber over the product and into contact with a
lower thermoplastic film on a conveyor belt. The belt which
has openings along its edges, moves over a fixed vacuum
plate having apertures at its edges and the space around
the product is evacuated through these openings and
apertures prior to pushing the upper film into skin-like
engagement with the product and into heat-sealing contact
with the lower film thereby to form a vacuum skin-package.
(2) Description of the Prior Art
Packaging methods and apparatus of this general
type are old. It is known, for example, to package an
article by pushing an upper film into engagement with the
article and a lower film by exerting air pressure on the
upper film, after evacuating the space around the
product, and various packaging techniques have been
utilized to do this.
U.S. patent 2,690,593 to Abercrombie, which
is exemplary of the prior art, for example, discloses
moving a heater housing and platen towards a base to
envelop an article positioned thereon in a plastic sheet
followed by subjecting the surface of the plastic sheet
to reduced pressure to shrink it about the article.
-2- ~r
106Z5~9
U. S. patent 2,799,5~9 to Grinstead et al.,
another example of this type art, discloses placing a
product within packaging material, the edges of which
are clamped to produce a fluid tight joint, after which
a greater pressure is applied to the outer surface of the
material than that existing on the inner surface of the
material to make a vacuum skin-package.
Further, U.S. patent 1,856,694 to Correvont
shows a device for laminating a sheet of pyroxylin onto
a shaped article, which device has means for gripping
and heating the sheet and for forcing the shaped article
against the sheet to produce a partial wrapping of the
sheet around the shaped article, and means for producing
lesser pressure on the article side of the sheet and
greater pressure on the opposite side thereof to complete
the wrapping of the heat-plasticized sheet around the
upper surfaces of the article.
Australian patent ~o. 245,77~ describes a
noncontinuous vacuum skin-packaging process wherein an
article to be packaged is placed on a lower packaging
member and inserted within a lower portion of a two-part
vacuum chamber. An upper web piece is positioned across
the lower part of the vacuum chamber and then the upper
part of the chamber is brought into engagement with the
lower portion to clamp the piece of upper web between
the llpper and l~wer ~acuum chambers, and fir~ally the
upper web is forced down and around the article and the
surrounding portion of the lower pachaging member to form
a vacuum skin-package.
1062599
In further teachings of related packaging
techniques inthisarea, U.S. patent 3,~91,504 to Young
et al. shows a packaging method in which a heated upper
film is draped over the product while preventing premature
sealing of it to a lower packaging member while air is
removed between the film and the packaging member, after
which the film is pushed against the product and the
packaging member to form a heat-sealed, s~in-packaged
product.
And, lastly, U.S. patent 3,910,008 to Johnson
shows a vacuum packaging system whereby upper and lower
films are vacuum sealed about an article at a sealing
station, after the space around such article is evacuated.
In the Johnson patent, the article being
packaged is placed on a lower embossed film having up-
wardly extending projections and vacuum is drawn about
the edges of this lower film and an upper film positioned
above the article and pulled tightly thereabout by such
vacuum. The projections allow substantially complete
evacuation of air from the enclosed artic~e before the
films become completely sealed together thereby to form
an airtight package,using this system.
In a-n important aspect of such system, the lower
film with the article thereon,is conveyed to the sealing
station by means engagable with the lower film at a point
downstream from the sealing station. Such conveying
system includes first and second support sections, a drive
roll and a pair of friction wheels. The wheels friction-
ally engage the flattened side portions o~ the completed
package in the nip between the wheels and the drive roller.
106Z5~9
Since the lower film is continuous, fresh film is drawn
~rom a storage roll or from an embossing assembly through
the apparatus in an amount about the distance each succes-
sive pac~age is moved. The amount of rotation is prede-
termined so that the appropriate amount of film will be
drawn into the sealing section.
The lower embossed film with its projections
directed upwardly is pulled through the first and second
support sections to the sealing section. At this location
the housing descends over the product and the upper film,
which is in a softened state and is secured to the periphery
of this housing by vacuum, stretches over the product
while the housing continues its downward movement. Simul-
taneously air is evacuated from the edges of the embossed
lower film. As the upper film continues to be lowered,
air is removed from the area about the product and such
air evacuation continues even after the upper film has
made initial contact with the top surfaces of the projec-
tions of the lower film. After substantially all the air
is removed, the some~ihat resilient projections become
collapsed due to the pressure differential between the
atmosphere and the reduced pressure between the films.
At this point ~he upper film commences to bond to the
lower film at the annular area of their overlap about the
product periphery and this continues unti sealing is
completed and the vacuum package is formed.
A problem with the above teachings, and with the
other known art, is their failure to give to the vacuum slcin-
packaging art, a relatively simple means and mcthod of
making a package, such as is found in the method and
106Z599
apparatus of this invention,in which apertures in a
conveyor belt moving over a fixed plate are aligned with
openings in the plate to permit evacuation of the space
around a product being packaged, after a movable one-part
vacuum chamber moves an upper film over the product and
into contact with a flat lower film, which films are then
pushed and sealed together to form a vacuum skin-package.
Summar~ of the Invention
Briefly summar-zed, this invention is a
method of making a vacuum skin-package including the
steps of:
positioning a lower film on a conveyor
belt, such belt having means defining
opposed sets of apertures spaced from
each other along the edges of the belt
and the lower film being positioned be-
tween the opposed sets of aper~ures in
the belt;
placing a product to be packaged on the
lower film between opposed sets of
apertures in the belt;
moving the belt having the lower film and
the product thereon to a package-forming
station above a fixed vacuum plate having
means defining opposed openin~s along the
- .edges thereof, such openings being aligned
with opposed sets of apertures in the
6.
106Z599
conveyor belt at the package-forming station,
such openings in the vacuum plate being
connected to a vacuum source;
engaging an upper film with a vacuum
chamber at the package-forming station;
heating the upper film;
moving the vacuum chamber and the heated
upper film downwardly so as to drape the
upper film around the product and to form
an hermetic seal between the vacuum
chamber, the conveyor be-t, the lower and
upper films and the vacuum plate and to
enclose therewithin the opposed sets of
apertures in the conveyor belt that are
aligned with the opposed openings in the
vacuum plate;
evacuating the space above the upper film
and also around the product, the latter
occurring through such aligned apertures in
the conveyor belt and openings in the~vacuum
plate while maintaining the h~rmetic seal
between the vacuum chamber, the upper and lower
films, the conveyor belt and the vacuum plate;
and,
pushing the upper film by pressure dif-
ferential into skin-tight conformity with
the product and into heat-sealin~ contact
with the lower film to form a vacuum
skin-package.
106Z599
In an important aspect of the embodiment of
this invention the upper film first is engaged with a
first holding means and moved to a position adjacent
the vacuum chamber whereat the upper film is transferred
from the holding means into engagement with the vacuum
chamber at the package-forming station.
In another important aspect the conveyor belt
with the lower film and product thereon is moved in a
first direction to the package-forming station and the
upper film is moved to the package-forming station in a
second direction which is transverse to the first direction
Preferably, vacuum means are used to hold the film against
the lower peripheral surface of the vacuum chamber. Lastly,
as so held at such package-forming station, the upper film
is in position to be moved downwardly in a third direction
perpendicular to the plane of the first and second direction
movements to start the package-forming operation.
This invention gives to the art a highly
practical method of and apparatus for making a vacuum
skin-package, in a continuous manner, with a minimum
of motions and parts, heretofore not available to it.
Brief Description of the Drawings
FIG. 1 is a perspective view of an apparatus
of this invention, which apparatus is suitable for
carrying out a method of vacuum skin-packaging, also of
this invention.
FIG. 2 is a sectional view of the apparatus
of FIG. 1 taken along lines 2-2 thereof (with parts
omitted for clarity).
F-2592
lO~Z599
FIG. 3 is a perspective view showing, in
greater detail, various parts of the apparatus of FIG. 1,
including means for creating a vacuum at a package-
forming station (including a movable vacuum chamber and
a fixed vacuum plate), and further showing a lower film
with a product to be packaged thereon positioned on a
conveyor belt which is movable to and past the package-
forming station.
FIG. 4 shows an upper film holding means~and
associated parts) with the upper film engaged thereby,
such holding means being adapted to be moved into a
package-forming starting position at the package-forming
station.
FIG. 5 shows another upper film holding means,
in the form of the movable vacuum chamber as shown in
FIG. 3, in a perspective showing.
FIGS. 6 and 7 are schematic showings of an
upper web severing means for partially, then fully,
severing the film to form a package memb-er at such
package-forming station.
FIG. 8 shows a cross-sectional view of parts
of the apparatus of FIG~ 1 in a package-forming starting
position at the package-forming station.
FIG. 9 shows the apparatus parts of FIG. 8 in
a packaging-forming first position at the package-forming
station.
FIG. 10 shows the apparatus parts of FIGS. 8
and 9 in a package-rorming seccnd position at the
p~ckage-forming station, with only lower film sevcring
106Z599
required at a later station to complete the package-
forming operation,
FIGS. 11-16 show, schematically, the operation
of various parts of the apparatus of this invention,
primarily the upper film first holding means and second
holding means (the movable vacuum chamber), and fixed
vacuum plate, in forming a vacuum skin-package in ac-
cordance with this invention.
Description of a Preferred Embodiment
This invention is a method of and apparatus
for making a vacuum skin-package.
Briefly described, such apparatus generally
includes:
Means for moving an upper film from a
supply source along a path to a package-
forming station;
means for moving a lower film with a
product to be packaged positioned thereon
along another path into a package-forming
starting position at the package-forming
station;
means for severing the uPper film to form
an upper package member, which member is,
without further movement, positioned in its
package-forming starting position at the
package-forming station; and
means for forming or mal;ing a vacul~m
skin-package at such package-forming station.
10.
106Z599
In essence, it is seen that such apparatus
generally performs two functions: (1) it places in
prepackage-positioning steps the upper and lower film~,
and the product being packaged, in their operative posi-
tions at the package-forming station and, (2) then
forms the vacuum skin-package at that station.
Referring to the drawings, and Figs. 1, 2 and
3 in particular, in starting to make such package an
upper thermoplastic film F-l is supplied from a supply
source S-l and moved along a first path P-l by appropriate
mechanical moving means to the package-forming station.
The supply source may be any appropriate source, for
example, it may be a roll of ionomer film.
~ t the package-forming station, the upper
film F-l is severed to form an upper package member P~
which, as formed,is in position ready to start the
package-making operation. The movement of the upper film
F-l to this station and the forming there of the package
member PM-l are first key steps in the making of the
package and further represent improvements in the art
of material handling.
- These steps in starting the making of a vacuum
skin-package in accordance with this invention, accord-
ingly, include the material handling method steps of:
engaging a portion of a film, such as
upper film F-l, supplied from supply source
S-l with a first holding means 11 located in
a first position in the path P-l of the film
(as seen in Fig. 11);
106Z599
moving the first holding means 11 and
engaged film F-l to a second position
located adjacent to a second
holding means 12 (as seen in Fig.
12);
transferring the film F-l from the first
holding means 11 to the second holding means
- 12 at such second position (as seen in Fig. 13);
rekurning the first holding means 11 to
its first position while the film F-l is held
in the second position by the second holding
means 12 (as seen in Fig. 14);
engaging another portion of the film F-l
at the first position by the first holding
means 11 (as seen in Fig. 15); and
severing the film F-l in a transverse
path between the first and second positions
to ~orm a package member ~-1 while the film
is held on either side of the transverse
severance path by the first and second holding
means 11 and 12 (a~ain as seen in Fig. 15).
In the preferred embodiment of this invention
being described, the second holding means 11 is a part of
a movable vacuum chamber, further to be described, which
holds the upper package member PM-l in its starting
position, in making a package, at the package-forming
station.
In the making of the package at this station
the material handling method of this invention includes
~ - \
~otiz599
the further steps of:
moving the second holding means 12 and
held package member PM-l to a third position
in a path perpendicular to the plane of the
path P-l of the film as a step in the
package-making method.
By following these basic material
handling steps, it is possible readily to bring the upper
package member PM-l into its proper position at the
package-forming station, ready to start the package-
making operation, using a minimum of parts and motions.
It, then, is only necessary to bring the lower film and
product to be packaged to this station, as later will be
described, to complete the preliminary prepackage-forming
positioning steps, prior to the package-making operation.
Upper Film Holding Means
As best seen in Figs. 2, 4 and 11-15, the upper
film F-l used to make the vacuum skin-package in accordance
with this invention is supplied from the upper film
supply roll S-l and is moved to the package-forming station
by use of the first (upper film) holding means 11 which
operates in the path P-l of the upper film supply (as best
shown by the direction arrow in Fig. 2).
Fig. 4 shows the first holding means 11 in
greater detail. The upper film F-l is held against the
upper surface of the first holding means 11 during dwell
and film moving sequences by use of vacuum holes 13
positioned around the upper peripheral surfaces thereof,
which holes are connected to a vacuum system 14. The
leading edge of the upper film F-l is shown adjacent to the
13.
~O~;Z~;99
leading edge of the first holding means 11 in this
figure.
This holding means 11 and its captive piece of
upper film F-l is moved, by appropriate means, under the
lower surface of the second holding means 12, as guided
by outer guides 15 and inner guides 16. The leading
edge of the first holding means 11 is lowered and
raised by a cam mechanism attached to these guides (not
shown in Fig. 4) during this movement. As thus moved, the
film is positioned adjacent a movable vacuum chamber 17,
of which the second holding means 12 is a part, and the
upper film F-l is transferred from the first holding
means 11 into engagement with t~e second holding means
12 of such vacuum chamber 17 at the package-forming
station.
In summary, at this stage of making the
package, the positionirg of the upper film in this
embodiment includes the steps of:
engaging the upper film F-l with a first
holding means 11;
moving the engaged upper film F-l to a
position adjacent the vacuum chamber 17; and
transferring the upper film F-l from
the first holding means 11 into engagement
with the vacuum chamber 17 at the package-
forming station.
Further, also in summary, a material handling
apparatus for so positioning the upper film includes:
the first holding means 11 for engaging
a portion of a film in the first position in
14.
106ZS9~
the path P-l of the film F-l;
means for moving the first holding means 11
and engaged film F-l to second position located
adjacent to the second holding means 12;
means for transferring the film F-l from
the first holding means 1~ to the second holding
means 12 at such second position;
- means for returning the first holding means
11 to its first position while the film F-l
is held in the second position by the second
holding means 12, such first holding means 11
being adapted to engage another portion of
the film F-l at such first position; and
means, later to be described in detail,
for severing the film in a transverse path
between the first position and the second
position to form a package member F~l-l while
- the film on either side of the transverse
severance path is held by the first and second
holding means 11 and 12.
In other embodiments of this invention, the
upper film (or an upper package member) may be brought
into engagement wi~h the second holding means 12 of the
vacuum chamber 17 manually, or by other appropriate
means.
Movable Vacu~ Chamber
Fig. 5 shows the movable vacuum chamber 17 in
greater detail.
~s previously explained, the sccond holdin~ mcans
12 is located at the mouth of this vacuum chamber 17, at a
15.
~062599
resilient lower surface 18 thereof, which surface is
adapted to form a fluid-tight seal when operatively
engaged with a fixed plate, later to be described, as
best seen in Figs. 9 and 10, in key stages in the
package-making operation. Such holding means 12 is con-
trolled by an upper film holding vacuum means which
controls the transfer of the upper film F-l and holds it
in place while it is severed, heated, and draped over
the product in later package-making stages.
.
In further detail, such chamber 17 includes
means defining a plurality of holes 19 around its lower
peripheral surface 18, which holes 19 communicate ~lith a
vacuum conduit means 20. The advanced upper film F-l
when in the starting position at the package-forming
station preferably is held against this lower surface 18
of the vacuum chamber 17 by actuating these vacuum means.
This surface 18 or mouth of the vacuum chamber 17J as
stated, is resilient for later effecting a ~luid-tight
seal in a package-making stage or step.
~ he vacuum chamber 17 additionally is equipped
with vacuum means, in the form of a vacuum conduit 21,
for forming a vacuum in the space 22 in the chamber
17 above the upper package member PM-l as
held by the second holding means 12 (as best seen in
Figs. 9 and 10) and for venting this space 22; means,
including a heater 23 p~sitioned in the upper part of
thc chamber 17, for heatinF the upper film r~l-l to a
f~rm~bl,~ condition; and means 2/~ for cooling sllch film
16.
106Z59~
and for keeping the second holding moans 12 at a
temperature low enough to prevent excessive heating of
the upper film F-l during the preliminary package-making
operations. The chamber vacuum means is operable through
a suitable three-way valve 25 and the upper film heater
23, as best 'shown in Fig. 8, is connected to a power
source by suitable heat~r power leads.
After the upper film F-l has been transferred
to the second holding means 12 of the vacuum chamber 17,
it is severed from the supply source to form the packa~e
member ~I-ls as further will be described. This member
PM-l is then'heated by the electric heater 23 as a last
preliminary step prior to the package-making operation.
Appropriate means, not shown, are provided for
moving this chamber 17 and ~he heated package member PM-l
held by the second holding means 12 from its starting
position at the package-forming station, as shown in
Fig. 8, downwardly, as a step in the package-forming
operation, as further will be explained.
Upper Film Severin~ Means and Method
In making a package according to this invention,
a method of a-nd means for severing the upper film F-l is
provided which further represents a means and method' of
severing film in other environments.
Broadly speaking, such film severing method
includes the steps of:
engaging a portion of a film, such as
upper film F-l, having first and second edges
e' and e" with a first holding means,suc}l as
17.
1~)625~
holding means 11;
engaging another portion of the film F-1
by a second holding means, such as holding
means 12; and
- severing the film, for example, using a
severing means 27, as shown in Figs. 6 and 7,
in a transverse path between the first and
second holding means while the film F-l is
held on either side by such first and second
holding means, such severing including
cutting the film F-l at the first edge e'
by moving a severing initiating means 29 into
the film at a position spaced from the first
edge e' and thereafter in a first direction
toward and through such first edge e' to form a
partial cut, and completing the severing of the
film by moving a severing completing means 30
in a second direction into the partial cut and
thereafter through the film F-l toward and
through the second edge e" thereof whereby
to sever the film F-l.
Preferably the film F-l is held by vacuum means
of the first and second holding means during severing.
And, as a preliminary operation, in the package-
making method, in a preferred embodiment of this invention,uch film-severin~ method includes the steps of:
engaging a portion of the film F-l
with the first holding means 11 located in a
first position in a path P-l Or the film;
18.
1062599
moving the first holding means 11 and
engaged film F-l to a second position located
adjacent a sec~nd holding means 12;
transferring the film F-l from the first
holding means 11 to the second holding means 12
at such second position;
returning the first holding means ll to
its first position while the film F-l is held
in the second position by the second holding
means 12;
engaging another portion of the film F-l
at the first position by the first holding
means ll; and
severing the film F-l in a transverse path
between the first and second positions while the
film is held on either side of the transverse
severance path by the first and second holding
means ll and 12, such severing including:
cutting the film F-l near the first edge
e' by moving the severing initiating means 29 into
the film at a position spaced from the first
edge e' and thereafter in a first direction
toward and through such first edge to form a
partial cut and
completing the severing of the film by
moving the severing completing means 30 in an
opposing second direction into the partial
cut and thereafter through the film toward
and through the second edge e" where~y to
sever the film.
19.
1~;25~9
Thi8 severing step form~ the package-member
PM-l, which, as severed, i8 in its package-forming
start-up position, as 80 held by the second holding
means 12 of the movable vacuum chamber 17.
The severing means 27 preferred for use in
accordance with this inventlon is shown in detail in
Figs. 6 and 7.
me ~irst cutting per~ormed by the severing
means 27 i~ in the ~orm of a first film-nicking step,
followed by a continued severing step. These operations
are respectively per~ormed by the severing initiating means
29 (preferably in the form of a knife blade) and the
severing completely means 30 (al~o preferably in the ~orm
o~ a knife blade), which blades are mounted on ~n endless
roller chain 31. The endlesæ chain 31 i~ driven by a
driv~ng ~procket 32 and i8 guided in its path by a take-up
idler sprocket 33 and fixed idler ~prockets 34. Pinion 35
is attached to driving sprocket 32 and is actuated by rack
36, by operation o~ an actuating rsck cylinder 37.
Fig. 6 shows the ~evering means 27 in it~
dwell positlon prior to the ~ilm severing operation.
At the start of the severing operation the first kni~e
blade 29 move~ into the upper ~ilm F-1 to produce a cut
or nick that is started inside the edge e' of the upper
film F-l and continues to and through the edge e~, as
shown by direction arrow 38 in Fig. 6.
The severing completing means 30 then meet~ the
upper ~ilm F-l at the end o~ the severance path formed by
the ~evering lnitiating means 29 and severs the remalning
-20-
106ZSC3~
portion of the upper film F-l in a transverse
and oppoæite direction. This manner o~ seYering
eliminates the hlgh cu~ting rorce~ and aæsociated rilm
dlstortion encountered when the complete tran~verse cutting
or severing is attempted with a single blade which i~
initiated agains~ one edge of the rilm and then through
it ~n a single direction.
Fig. 7 shows the severing means as it appears
on the completion o~ the severing operation. me first
kni~e blade 29 traverse~ the path acro~s the film F-l in
an upright position situated above the film in an inverted
configuration a~ shown in Fig. 7, whlle the second blade
completes the severlng o~ ~he film F-l to form, in an
embodiment o~ this invention, the package-member PM-l.
Continuing with the starting,
prepositioning steps involved in the making o~ the package,
as best ~een in Figs. 1 and 3, a lower thermoplastlc film
F-2 is supplied ~rom a supply source, such as supply roll
S-2, and moved in a second path P-2 to the package-
forming ~tation. This phase of the method of making æuchpacksge includes the predetermined positioning o~ the
lower ~ilm F-2 on a conveyor belt 39. Thls belt 39 has
mean~ de~ining opposea sets 40 o~ apertures 41 spaced from
each along the edges o~ the belt, as beæt seen in Fig. 3,
and the lower film F-2 is positioned between and spaced
~rom these opposed sets o~ apertures 41, so that they
may remain open.
A product P to be packaged is then placed on
the lower film F-2 between opposed 8ets 40 of apertures
in such belt 39. The belt 39 having the lower film F-2
-21-
10&i25~9
and the product P 80 positioned thereon is moved to the
package-formlng station, by appropriate meanB~ and above
a ~ixed vacuum plate 42 further to be described and in
operative relationship therewith. In this position, the
lower film F-2 and the product P are in their starting
positions, ready for the package-forming steps to begin.
Fixed Vacuum Plate
Fig. 3 shows, in greater dekail, the fixed
vacuum plate 42 that is used in con~unction with the
movable vacuum chamber 17 to produce the vacuum enclosure
that m3kes possible the making o~ a package by the method
o~ this invention. me plate 42 contains openings 43 at it~
edges covered with fine mesh screens that communicate with
a vacuum pumping system 44 to remove air through such
openings.
The cut-away view o~ the belt 39, as ~een ln
Fig. 2, for example, shows the spaced aperture 41 in such
belt that permit passage of air through the belt 39.
As shown, the opposed openingc 43 along the edges of the
plate 42 are aligned with oppo~ed apertures 41 in the belt
39 at the package-forming ~tation. Air i~ drawn through the~e
apertures 41 and openings 43 to form a vacuum around the
product, when forming the package.
The plate 42 further i8 provided with means for
heating the lower film, in the form o~ heating elements 45,
such as cartridge heaters, whereby the lower fil~ F-2
will be rendered heat-sealable to the upper film F-l in
making the package.
In greater detail the fixed vacuum plate 42
preferably i8 machined from a ~olid metal block and
-22-
-
~Z59~
contains a temperature ~ensor. The openings ~3
in the plate 42 preferably are covered by the
screens or sintered metal. The entire block or
plate may be heated.
In other pre~erred aæpects of this invention,
the upper film supply roll S-lis po~itioned at a right
angle relative to the lower film supply roll S-2,
accordingly, the film paths P-l and P-2 are at right angleæ
to each other in the movement of the respective films to
the package-forming station.
Upon completion o~ the package-making operation,
a~ will ~ow be described ln detail, the conveyor belt 39
continues its movement, to the left as shown in Fig. 3, for
example, carrying with it the lower film F-2, the product
P, and the upper package member PM-l, which is in skin-
like contact with the product P and heat-sealed to the
lower ~ilm F-2.
Preferably, ~rom the package-making statlon
these parts are next ved to a cooling station, as best
shown in Fig. 1, to aid in the separation of the lower
film F-2 from the conveyor belt 39. From this station,
after separation, the partæ are moved to a final ~tation
consi~ting, for example, of a guillotine cut-o~ knife
which cuts such lower film F-2 and completes the formation
of an individual vacuum skin-package.
In other embodiments o~ this invention, the
upper film F-2 may be moved to the package-forming
~tation by tenter clips, such as are used in a typical
1~6Z~
tenter frame. The~e clip~ pre~erably are ~paced in sets
on continuous chainæ and perform similar functions to the
first holding means 12 in the preliminary ætepæ of the package-
~orming operation. Pre~erably, the belt 39 is o~ Kapæton~
polyimide film.
After the upper film package PM-l, the product P
and the lower film or package member PM-2 are in their opera-
tive positions at the package-making ætation, aæ æhown in
Fig. 8, the package-making operation may begin.
Method o~ Making the Package
Broadly described, a method of making a vacuum
ækin-package according to this invention includes the
æteps of:
positioning the lower ~ilm F-2 on the
conveyor belt 39, such belt 39 having mean~
defining oppoæed æets 40 o~ apertures spaced
from each other along the edgeæ of the belt and
the lower ~ilm F-2 be~ng positloned between the
opposed setæ 40 of apertures in the belt 39;
placing the product P to be packaged on
the lower film F-2 between opposed ~et~ 40 of
apertures in the belt;
moving the belt having the lower ~ilm F-2
and the product P thereon to the package-forming
~tation above the fixed vacuum plate 42 having
means defining opposed openings 43 along the
edges thereof, such openings 43 being aligned
with oppo~ed set~ 40 of apertureæ 41 in the
conveyor belt 39 at the package-~orming st~ ion,
-24-
l~;Z599
engagin~ the upper package member PM-1
with the vacuum ch~mber 17 at the package-
~orming station;
heating the upper package member PM-l;
moving the vacuum chamber 17 and the heated
upper package member PM-1 downwardly 80 as to
drape this member around the product and to form
a hermetic ~eal between the vacuum chamber 17,
the conveyor belt 39, the lower film F-2, upper
package member PM-l and the vacuum plate 42 and
to enclose therewithin the opposed setæ 40 of
apertures 41 in the conveyor belt that are
aligned with the opposed openings 43 in the
vacuum plate 42 (a~ shown in ~ig. 9);
evacuating the space above the upper package
mem~er PM-l and also around the product P, the latter
occurring through such aligned apertures 41 in
the conveyor belt 39 and openings 43 in the
vacuum plate 42 while maintaining the hermetic
~eal (as ~hown in Fig. 9); and
puæhing the upper package member PM-l by
preg~ure differential into skin-tight conformity
with the product P ~nd into heat-sealing contact
with the lower film F-2 (8S shown in Fig. 10)
to form a vacuum skin-package.
Such method also may include:
engaging the upper film F-l with the
firæt holding means 11;
moving the engaged upper film F-l to a
~25-
10~ 9
position ad~acent the vacuum chamber 17;
and
trans~erring the upper film F-l from the
first holding means 11 into engagement with the
vacuum chamber 17 at the package-forming station.
Pre~erably, in this method, the conveyor belt 39
with the lower film F-2 and the product P thereon iB moved
in a first direction to the package-forming station, and
the upper film F-l i~ moved in a second directlon transverEe
to the rirst direction to the package-forming station. And,
lastly, the vacuum chamber 17 and heated upper film F-l
are moved downwardly in a th~rd direction or path P-3
perpendicular to the plane of the ~ir~t and second direc-
tion paths P-l and P-2 to the package-~orming station so
as to drape such upper film F-l around the product P and
to ~orm the hermetic seal between the vacuum chamber, the
conveyor belt, the loNer ~ilm, the upper package member and
the vacuum plate and to enclose therewithin the opposed ~ets
o~ apertures 41 ~n the conveyor belt 39 that are aligned
with the opposed openings 43 in the vacuum plate 42.
A method and apparatus of this invention for making a
vacuum skin-package i8 ghown in ~lgs. 8, 9 and
10.
In Fig. 8, lower ~ilm F-2 and the conveyor belt 39
are shown ln a ~ectional view transverse to the run o~ the
conveyor belt 39 while the upper package member PM-l i8
shown in a sectlonal view taken along the run o~ the upper
film F-l which i8 normal to the directlon o~ the conveyor belt
39. The upper ~ilm F-l has been supplied ~rom the upper film
supply roll S-2 as ha~ been described in detail. me
-26-
iZ5~9
upper package member PM-l, as shown, is maintained in
position at the mouth of the vacuum chamber 17 by means of
the second holding means 12 which is a part of the vacuum
chamber 17 and is connected to the upper vacuum system 20
via the vacuum holding ring. The chamber vacuum system 21
is not in it6 operative ~tate in Fig. 8 since the three-
way valve controlling it ~ 8 ln the vented position. me
hester 23 is energized to warm the upper package member PM-l
sufficiently to enable it to be drawable.
me lower film F-2 ~hown in Fig. 8 i8 positioned
on the conveyor belt 39 between the conveyor belt apertures
41 while the product P i8 positioned on the lower film F-2.
The plate heaters 45 provlde sufficient heat through the
conveyor belt 39 to keep the upper surface of lower film
F-2 in a condition for rapid bonding to the heated upper
package member PM-l.
Fig. 9 shows the package-forming operation when
the vacuum chamber 17 has been closed to form a hermetic
seal with the ~ixed plate 42 while portions of the conveyor
belt 39, upper package member PM-l and lower film F-2 are
contained within the sealing area bounded by the fixed plate
42 and the resilient lower gurface of the vacuum chamber 17.
In this sealing position air is removed from above the upper
package member PM-l via the chamber vacuum system 21 and its
upper three-way valve and is removed below the upper member PM-l
and from around the product P vla the lower vacuum system
44 and it~ lower three-way valve. Thus, the lower film F-2
and product P are situated in a vacuum under complete cover
of the upper package member PM-l.
-27-
1062599
The final stage of the vacuum skin-packaging
operation i8 shown in Fig. 10. Vacuum beneath the upper
package member PM-l i6 maintained through the lower vacuum
~ystem 44 while the space in the vacuum chamber 17 above
the upper package member PM-l i8 vented to the atmosphere
vla the chamber vacuum sy~tem 21 and its three-way valve.
The differential pre~sure resulting acro~s the heated upper
package member PM-l forces it down around the product P
into skin-tight conformity and into heat-sealing contact
with the lower film F-2 around the confines of the product
P to produce the skin-tight vacuum package ~hown in a cross-
~ectional view in Fig. 10. This, in e~sence, completes the
making of the package.
-28-
