Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02800692 2012-11-23
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Method and Device for the Portioned Packaging of a Food Mass
The invention relates to a method for the portioned packaging of an at least
substantially incompressible food mass, of processed cheese in particular,
which is filled as a flowable mass into a tubular wrapping comprising a
thermoplastic plastic film. The invention further relates to a device for
carrying
out the method.
Various methods are known for the portioned packaging of such a food mass.
In some methods, the food mass is poured into shells, which are preformed of
a stable film, more particularly plastic. The individual shells filled with
the food
mass are subsequently closed and separated from one another. The
disadvantage of this solution is that a separate tool or even a separate
machine
is required for each working step, more particularly preshaping, filling,
closing
and separating. In addition, the portioned filling of preshaped packages with
such a food mass is relative complex in terms of adjustment.
Basically, three methods are known for packaging processed cheese: It is
known, for instance, to bring the processed cheese into slice form and to
stack
these individual slices on top of one another, "slice on slice". It is also
known to
make individually packaged slices ("individual wrapped slices", IWS). To this
end, a film tube is filled with processed cheese and smoothed into a strip
before it is subdivided into individual slices by displacement, sealing and
cutting. Another way to package processed cheese is to enclose individual
portions in aluminum foil. Such portions are known as triangular shapes, a
plurality of which is placed together in a circle in one common outer
packaging.
The individual portions can be provided with a string, as the tear-open aid,
which cuts through the foil. Such portioned packaging in aluminum foil is
relatively complex.
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The problem addressed by the present application is therefore that of
providing
a method for the portioned packaging of a food mass, more particularly
processed cheese, in which the individual packages of the food mass can be
manufactured in a simple and low-cost manner in various shapes and which
are easy for the consumer to handle. A corresponding problem addressed by
the invention is that of providing a device for implementing the method.
These problems are solved by a method having the features of claim 1 and by
a device having the features of claim 7. Advantageous embodiments are
mentioned in the dependent claims.
The significant fundamental idea of the invention is to fill the food mass
into a
film tube and subsequently deform it by deep drawing while maintaining the
presence of the food mass. To this end, the food mass is basically displaced
out of regions of the completely filled tube into regions in which deep
drawing
takes place quasi simultaneously. A separate deep-drawing punch is not
required, however. The food mass functions as a punch and presses the film
into the mold of the tool. The mass that is excessive in the regions of the
displacement finds space in the newly formed regions. To this end, according
to the invention, the thermoplastic plastic film of the wrapping enclosing the
food mass is reshaped in a mold into individual units, each defining a
portion,
with displacement of the food mass out of sealing areas. Said units disposed
one behind the other in a chain are delimited from one another by way of
sealing in the sealing area and are subsequently separated from one another.
Such a unit is also referred to in the following as a cavity filled with the
food
mass. The cavity defining a portion of the food mass is therefore formed,
according to the invention, in the film strip, which is already filled. The
flowable
food mass enclosed by the film strip thereby completes the shaping of the film
layer and assumes the shape of the cavity. The shaping of the film strip and a
portioning of the food mass are therefore concomitant.
The method according to the invention makes it possible to manufacture easy-
to-handle individual packages in an automated manner. The method can
replace the subsequent filling of preformed shells. As a result, the
production of
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individual packages filled with food mass is greatly simplified and product
output is markedly increased. Due to the simultaneous shaping of the film tube
and the food mass, the method is suitable more particularly for the portioned
packaging of processed cheese, since processed cheese is particularly easy to
handle because the viscosity thereof can be adjusted via temperature. The
method makes continuous production possible. At the same time, it offers high
variability in terms of the possible packaging shapes. The cavities can be
formed in the filled film strip in nearly any shape and, due to the three-
dimensional orientation thereof in particular, they offer a great deal of
freedom
for product design.
It is particularly advantageous that the shaping of the filled film strip,
according
to the invention, can be integrated into existing production systems for
packaging food masses. It is therefore possible to retrofit or expand
previously
used machine lines for the new method.
In a preferred embodiment, both film layers of a double-layer film tube filled
with food mass are molded. By forming opposing cavities in the double-layer
film strip, it is possible to increase the total volume of the individual
package
that is available. Shaping the double-layer film strip on both sides also
makes it
possible to obtain a symmetrical design of the top part and the lower part of
the
individual packaging. For the case of an asymmetrical design, a top part of
the
forming means is designed smooth, for example, while the lower part
comprises shaping cavities.
A vacuum is preferably applied in a forming means to support the formation of
the cavities in the film layer. The vacuum induces a type of deep-drawing
effect
on the film layer. It is applied while the mold segment of the forming means
closes in the sealing area of the double-layer film strip. The vacuum is
deactivated before the shaping means is opened. The film layer is thereby not
only pressed into the mold segment, it is also drawn in via suction. It comes
to
line the walls thereof and assumes the shape thereof. The vacuum induces a
precise molding of the predefined shape by way of the thermoplastic film.
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The food mass is thereby not only displaced out of the sealing areas, it is
also
suctioned into the mold segments. It follows the shaping of the film layer and
fills the mold segment. Only a slight amount of food mass remains in the
sealing area due to the combination suction and displacement effect acting on
the food mass, thereby simplifying the subsequent sealing of the film layers
in
the sealing area. It is particularly advantageous when the vacuum is adapted
to
the food mass in terms of level and duration.
Temporary and local heating of the thermoplastic plastic film supports the
formation of the cavities in the film strip. To this end, the regions of the
forming
means coming in contact with the film to be reshaped are heated.
Thermoplastic plastics of different types and film thicknesses can be
processed
using the method and the device. Films made of PE, PET and PP are suitable
in particular. The preferred film thickness is between 20 pm and 100 pm. The
method also makes it possible to use film tubes made of film strips of
different
materials. Film strips made of thermoplastic plastic and aluminum foil can be
combined, for example.
Preferably, a separating segment of the forming means is first moved into the
food mass enclosed by the film strip. Said separating segment, which is
designed as a type of hold-down device, moves into the production strand
before the individual packages are shaped. It therefore delimits the part to
be
reshaped from the rest of the film tube. This subdivision of the product
strand
defines the region of the filled film tube that is available for the forming
process.
The segment prevents food mass from flowing out of the rest of the production
strand into the part of the film strip to be reshaped while the cavities are
being
formed. It is thereby possible to minimize fluctuations in the volume of the
individual packages that are produced.
To ensure that the product strand becomes detached from the forming means,
a vacuum is preferably applied to the cavities of the forming means. To this
end, it is advantageous to use the vacuum connection to also supply vacuum.
The forming means preferably also comprises a means for sealing the sealing
area located between the consecutive hollow shapes. Since the forming means
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not only forms the cavities in the filled film strip, but also seals the
sealing area,
this working step can be combined in one tool. It is therefore easier to
change
the shape of the individual packages. Such shape changes usually involve
changing the shape and position of the sealing area between the individual
packages. When the packaging shape is changed, the effort required for set up
at the packaging system is therefore reduced.
In a particularly preferred embodiment, the sealing area separating the
cavities
is sealed using ultrasound. Using ultrasound for sealing has the great
advantage over sealing using heat that a seam sealed using ultrasound is
easier to re-open later, that is, it has better "pealability". In addition,
the
ultrasound displaces any remaining quantities of food mass out of the sealing
area. A product inclusion in the sealing seam is prevented. This ensures
uniform strength of the sealing seam. In addition, a product inclusion in the
sealing area is perceived by the customer as an impairment of quality. The
clean sealing seam increases the appearance of quality of the final product.
The sealing by way of sonotrode and sealing anvil can take place in a separate
working step. The forming means itself, more particularly the lateral
delimitations of the shaping cavity thereof moving into the sealing area, are
preferably designed as a sonotrode. The sealing components are therefore
integrated into the forming means.
At the end of the process, the film strip is cut in the sealing area. The
packages
of food mass, which have been separated from one another, are then fed
individually to the further packaging process. The individual working steps of
the shaping, sealing and separation of the individual packages are preferably
combined in direct succession. In order to retrofit the production system for
another packaging shape, it is therefore only necessary to replace the forming
means and the separating device. In a particularly preferred embodiment, the
separating device is part of the forming means.
In a further particularly preferred embodiment, the food mass is cooled before
the filled film strip is shaped. In contrast to pouring a liquid food mass
into a
preshaped packaging mold, when the cavities are formed according to the
invention, the food mass is pressed therein and is preferably also suctioned
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therein. The consistency of the food mass is therefore not required to be
liquid
but merely flowable in order to fill the cavities formed in the film strip.
The food
mass has already cooled to a great extent when the cavities are formed in the
film layer. It is therefore possible to eliminate complex cooling of the
shaped
individual package in order to prevent deformations in the further course of
the
production process, and to eliminate having to fill secondary packages. In
order
to perform cooling before shaping, the food mass is preferably guided along a
cooling path using cooling belts in a manner known per se, or said food mass
is
directed through a cooling water bath. This ensures uniform cooling of the
food
mass. The film can be supplied before or after cooling.
In a further particularly preferred embodiment, the edge regions of the two
film
layers overhanging at a longitudinal sealing seam form an opening tab for
opening the package. The two film layers are connected to one another via the
longitudinal sealing seam before the cavities are formed. Depending on how
the double-layer film strip was placed, it comprises one or two longitudinal
sealing seams. If a single film is placed so as to form a double-layer film
strip, it
comprises a longitudinal sealing seam on one side, which connects the lateral
end regions of the two film layers to one another. The variant of a double-
layer
film strip formed of two film layers comprises longitudinal sealing seams on
both sides. The film layers are dimensioned in such a way that film edge
regions of the joined film layers overhang after the longitudinal sealing seam
is
sealed. Pulling the overhanging film edge regions apart first opens the
longitudinal sealing seam and, as pulling continues, opens the sealing areas
of
the individual package. The packaging portion can thereby be easily opened
completely and the contents thereof can be removed from the packaging
without leaving any traces behind.
The overhanging film edge regions are preferably cut off in such a way that
the
remaining film edge region of the two film strips has the shape of a tab
protruding from the individual package. The tab shape is intuitively
recognized
by the customer as an opening mechanism for the individual package, and
therefore no further instructions on the package are required.
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In a further preferred embodiment, the two-layer film strip is in continuous
forward motion. This creates an endless, continuously self-renewing product
strand of the filled film strip. Automatic repositioning of the forming means
during the forming process makes it possible to continuously manufacture
individual packages of the food mass with correspondingly high product output.
The method or the device according to the invention makes it possible to
manufacture packaging portions in highly diverse shapes. In addition to the
popular cheese wedge shape familiar to the consumer, it is also possible to
form square or rectangular cavities in the film strip. The cavities can be
formed
in one film strip or in both film strips symmetrically or asymmetrically with
respect to one another. A further variable is the material that is selected
for the
films. The possibilities for variation therefore range from a symmetrical
package
having film strips made of plastic that are identically shaped on both sides
and
a sealing seam encircling the package in the center, to a package shaped on
one side and having an off-center sealing seam, the non-reshaped aluminum
foil strip of which closes the package in the manner of a cover.
In contrast to the known packages made of aluminum foil, the use of a
transparent plastic film provides the consumer with a direct view of the
packaged product. Additions such as herbs or nuts need not be only indicated
on the label; the customer can even see them in the product itself. By
coloring
the film strip specifically according to type, it is preferably possible to
identify
the contents of the package.
An embodiment of the invention is described in the following by reference to
figures 1 to 11. Shown are
Figure 1: shows an opened forming tool with a still undeformed production
strand of the enclosed food mass;
Figure 2: shows a sectional drawing along the line A-A of figure 1;
Figure 3: shows the closing forming tool as it begins to move into the
product strand;
Figure 4: shows a sectional drawing along the line B-B of figure 3;
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Figure 5: shows the closing forming tool with a closed separating segment
that has penetrated the product strand;
Figure 6: shows a sectional drawing along the fine C-C of figure 5;
Figure 7: shows the forming tool after completion of the forming process;
Figure 8: shows a sectional drawing along the line D-D of figure 7;
Figure 9: shows a hold-down device of the forming tool;
Figure 10: shows a base plate of the forming element comprising mold
segments;
Figure 11: shows a schematic representation of the various shaping steps
on the product strand.
Figures 1 to 8 show a forming means according to the invention in the form of
a
forming tool 1. The forming tool is depicted in a series of various phases of
the
process of forming the film strip 2 filled with food mass.
In figures 1 and 2, the forming tool 1, which comprises an upper part 3 and a
lower part 4, is open and has no contact with the production strand of the
film
strip 2. The upper part 3 and the lower part 4 of the forming tool 1 are
oriented
toward the top side and the underside, respectively, of the production strand
and are disposed opposite one another in a mirror-image manner. The upper
part 3 and the lower part 4 are of substantially identical construction, and
so
information regarding features or movements of one part 3, 4 of the forming
tool 1 always also relate to the other part 3, 4 in a mirror-image manner.
Each part 3, 4 of the forming tool 1 comprises a base plate 5 and a mold plate
6, which is disposed on the side of the base plate 5 facing the production
strand and is detachably connected thereto. A separating segment 7, as a type
of hold-down device, projects from the part 3, 4 in the direction of the
production strand. The base plate 5 and the hold-down device are connected to
one another via a guide B. The guide 8 is preloaded via springs 9 and permits
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the hold-down device to move relative to the base plate 5. The base plate 5
further comprises a vacuum and compressed air connection 10, which is
connected to a hollow chamber 11 incorporated in the mold plate 6. A vacuum
is applied at a mold segment of the forming tool 1 via the hollow chamber 11.
The hollow chamber 11 is delimited on the product-strand side by an insertable
base 12, which is separated from the base plate 5 by way of a spacer sleeve
13. The insertable base 12, in combination with webs 14 of the mold plate 6
protruding laterally from the insertable base 12 in the direction of the
production
strand, forms a mold segment 15, which is open toward the filled film strip 2
and into which the film strip 2 is formed. The mold segment 15 therefore forms
a female mold for the film strip 2 filled with the food mass 16.
The film strip 2 filled with food mass 16 comprises two film layers 17, 18,
which
are connected to one another on both sides via longitudinally extending
sealing
seams 19. Film edge regions 20 protrude from the double-layer film strip 2
along the longitudinal sealing seams 19. The mold plate 6 comprises two
temperature-controlled cartridge heaters 21 for the temporary and local
heating
of the thermoplastic film layer 17, 18.
Figures 3 and 4 show the forming tool 1 at the beginning of the closing
process. At this point in time, an outer surface of the hold-down device 7 is
located at the level of the still non-deformed product strand of the filled
film strip
2. The hold-down device 7 comprises a heating element, which is not shown
here, in order to heat the thermoplastic plastic film to be deformed. The
heated
hold-down device 7 is offset on either side with respect to the enclosed food
mass 16 and is disposed above the film edge regions 20 of the double-layer
film strip 2. To prevent the film edge region 20 from becoming heated by
contact with the heated hold-down device 7, the hold-down device 7 comprises
a longitudinally extending insulating element 21 on both sides, which
externally
adjoins a longitudinal web 22 of the hold-down device protruding in the
direction of the production strand. The hold-down device 7 also comprises two
cross webs, which are not shown here and extend transversely overall with
respect to the production strand, said cross webs contacting the double-layer
film strip 2 in this position of the closing process.
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In figures 5 and 6, the hold-down devices 7 are closed by the upper part 3 and
the lower part 4 of the forming tool 1, and therefore the film edge regions 20
are held between the longitudinal webs 22 and the insulating elements 21. In
this position of the forming tool, the cross webs of the hold-down devices 7
have fully penetrated the product strand. The cross webs, which are disposed
at the beginning and at the end of the hold-down device 7 relative to the
production strand, therefore seal the region of the production strand to be
deformed by the forming tool 1.
Figures 7 and 8 show the forming tool 1 with the upper part and the lower part
3, 4 completely closed. When the vacuum is applied into the mold segments
15, the pressure plate 5, together with the mold plate 6, in both parts 3, 4
moves in the direction of the production strand. The heated webs 14 of the
mold plates 6 thereby penetrate the product strand in opposition, deform the
thermoplastic film layer 17, 18 at this point, and displace the food mass 16
located in this region of the product strand. The food mass 16 presses the
film
layers 17, 18 into the mold segments 15. The food mass 16, which is at least
nearly incompressible, functions as a deep-drawing punch that presses the film
layer 17, 18 into the mold segments 15. Cavities 23, each defining a portion
of
the food mass 16 and following one another individually, are thereby formed in
the film layers 17, 18.
In addition, the film layer 17, 18 is drawn against the heated insertable base
12
via the vacuum present in the mold segment 15. The vacuum is applied after
the hold-down device 7 has fully penetrated the product strand. The strength
and the duration of the vacuum are adapted to the food mass. The food mass
16, which is still flowable and has been displaced from the region of the
closing
webs 14, completely fills the cavity 23 that forms.
In the exemplary embodiment described here, two opposed cavities 23 form a
single portion of the food mass 16 in each case. The shape of the portion is
defined by the mold segments 15 of the parts 3, 4.
The mutually impacting webs 14 of the mold plates 6 press the film layers 17,
18 together and define a sealing area 24 encircling the individual packages.
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The sealing area 24 is sealed using an ultrasonic sealing method known per se
in order to permanently shape the individual packages. The webs 14 function
as a sonotrode (welding horn), and therefore the sonotrode and sealing anvil
sealing components are integrated in the forming tool. The two working steps
can also be carried out by two tools that follow one another in the production
process.
After the individual packages are fully formed, the vacuum in the mold segment
15 is no longer maintained. The parts 3, 4 of the forming tool move apart from
one another and release a strand of fully formed, consecutive individual
packages of the food mass 16.
During the method steps described by reference to figures 1 to 8, the forming
tool moves at a speed v, which corresponds to the speed vp of the
continuously moving production strand. After opening, the forming tool 1 moves
along the production strand opposite the conveyance direction back into a
starting position, from which a new work cycle starts. When the forming tool 1
closes, the rear - relative to the production direction - web 25 of the hold-
down
device 7 moves from the starting position of the forming tool 1 to the
boundary
of the strand section that was formed by the front web 25 in the previous work
cycle.
Figure 9 shows a hold-down device 7 of the type described, in an axonometric
representation. Shown clearly are the webs 22 extending parallel to the
production strand, against which the insulating elements 21 on both sides
bear.
The webs 22 are connected to one another via two webs 25, which extend
transversely overall and penetrate the production strand when the hold-down
device 7 closes. The webs 25 delimit the section of the production strand that
can be deformed in one work cycle of the forming tool. The leads 26 for the
heating element, which is not shown, and the associated sensors are disposed
laterally on the hold-down device 7.
Figure 10 shows an axonometric representation of a base plate 5 having a
mold plate 6 fastened thereon. The webs 14 that laterally delimit a mold
segment 15 protrude from the mold plate 6. The insertable base 12 forms the
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base of the mold segments. The selection of the mold segments 15, in the
shape of cheese wedges in this case, defines the shape of the individual
packages.
Figure 11 shows a production strand of the filled film strip 2 at various
points in
time of the forming process, which occur one after the other in the production
strand. Cavities 23 are formed in the double-layer film strip 2, which is
filled
with food mass 16 and is sealed by way of two longitudinal sealing seams 19,
said cavities being separated by a sealing area 24 into cavities 23 that are
disposed one after the other and define the individual package 27 of the food
mass. The sealing area 24 encircling each individual package 27 is sealed by
way of ultrasonic sealing means, thereby removing any remaining food mass
16 from the sealing area 24 that has not yet been displaced by the webs 14. In
a further method step, the consecutive individual packages 27 are separated
from one another. In so doing, the film edge regions 20 are cut off in such a
way that a remaining film edge region of the two film layers 17, 18 forms an
opening tab 28 for the individual package 27.
