U.S. patent application number 15/796075 was filed with the patent office on 2018-05-03 for skin packaging machine.
The applicant listed for this patent is Ulma Packaging Technological Center, S. Coop.. Invention is credited to Nicolas ARREGI ARAMBARRI, Eneko IZQUIERDO ERENO.
Application Number | 20180118385 15/796075 |
Document ID | / |
Family ID | 57354310 |
Filed Date | 2018-05-03 |
United States Patent
Application |
20180118385 |
Kind Code |
A1 |
ARREGI ARAMBARRI; Nicolas ;
et al. |
May 3, 2018 |
Skin Packaging Machine
Abstract
A skin packaging machine in which a first continuous film and a
second continuous and thermoplastic film above the first film are
supplied in a forward direction of the machine. The machine
includes a sealing station configured for receiving both films, and
it comprises an upper tool pressing on the films to seal them to
one another, with a closed holding contour delimiting the area of
said films being sealed. The sealing station further comprises a
sealing gasket attached to the holding contour, the sealing gasket
having, on each side with respect to the forward direction, an
operation zone with a notched configuration which is facing the
space delimited by said sealing gasket.
Inventors: |
ARREGI ARAMBARRI; Nicolas;
(Onati, ES) ; IZQUIERDO ERENO; Eneko; (Onati,
ES) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ulma Packaging Technological Center, S. Coop. |
Onati |
|
ES |
|
|
Family ID: |
57354310 |
Appl. No.: |
15/796075 |
Filed: |
October 27, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65B 41/02 20130101;
B65B 61/005 20130101; B65B 11/52 20130101; B65B 25/001
20130101 |
International
Class: |
B65B 11/52 20060101
B65B011/52; B65B 41/02 20060101 B65B041/02; B65B 61/00 20060101
B65B061/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2016 |
EP |
16382497.2 |
Claims
1. A sealing station configured to receive a first film and a
second film disposed above the first film, the sealing station
having a rearward entrance side and a forward exit side and
configured to seal the second film to the first film, the sealing
station comprising: a lower tool that is configured to support the
first film; and an upper tool positioned above the lower tool, in a
first arrangement the upper and lower tools are in contact with one
another, in a second arrangement the upper and lower tools are not
in contact with one another, the upper tool including a heating
surface and a gasket that is configured to urge the second film
against the first film when the upper and lower tools are in the
second arrangement, the gasket having a first side with a first
operation zone, the first operation zone including notches that are
separated by trenches, the notches facing inward into a space
delimited by the gasket, the heating surface having a plurality of
suction holes that are configured to draw the second film towards
the heating surface when a suction is applied through the suction
holes, the notches and trenches of the first operation zone being
configured to cause the second film to be deformed inside the
trenches in a tensed state to inhibit or reduce the formation of
creases in the second film when the second film is drawn toward the
heating surface.
2. The sealing station according to claim 1, wherein the notches of
the first operation zone are configured to limit the deformation of
the second film in the trenches in a manner that postpones a
contact of the second film with the heating surface when the second
film is drawn towards the heating surface.
3. The sealing station according to claim 1, wherein the gasket
comprises a second side opposite the first side, the first and
second sides of the gasket extending lengthwise in a direction
transverse to the rearward entrance side and forward exit side of
the sealing station, the second side the gasket having a second
operation zone, the second operation zone including notches that
are separated by trenches, the notches facing inward into the space
delimited by the gasket, the notches and trenches of the second
operation zone being configured to cause the second film to be
deformed inside the trenches in a tensed state to inhibit the
formation of creases in the second film when the second film is
drawn toward the heating surface.
4. The sealing station according to claim 3, wherein the notches of
the second operation zone are configured to limit the deformation
of the second film in the trenches in a manner that postpones a
contact of the second film with the heating surface when the second
film is drawn towards the heating surface.
5. The sealing station according to claim 1, wherein the trenches
of the first operation zone have a same first width and the notches
of the first operation zone have a same second width, the second
width being greater than the first width.
6. The sealing station according to claim 3, wherein the trenches
of the first and second operation zones have a same first width and
the notches of the first and second operation zones have a same
second width, the second width being greater than the first
width.
7. The sealing station according to claim 1, wherein the gasket has
a first width outside the first operation zone, the notches of the
first operation zone have a second width that is substantially the
same as the first width.
8. The sealing station according to claim 3, wherein the gasket has
a first width outside the first and second operation zones, the
notches of the first and second operation zones have a second width
that is substantially the same as the first width.
9. The sealing station according to claim 1, wherein the gasket has
a thickness that is substantially uniform around an entire
perimeter of the gasket.
10. The sealing station according to claim 1, wherein the trenches
of the first operation zone have a same length and the notches of
the first operation zone have a same second length.
11. The sealing station according to claim 3, wherein the trenches
of the first and second operation zones have a same length and the
notches of the first and second operation zones have a same second
length.
11. The sealing station according to claim 1, wherein the first
side of the gasket is disposed transverse to at least one of the
rearward entrance side and forward exit side of the sealing
station, the first side having a first length, the first operation
zone extending less than the entire first length.
12. The sealing station according to claim 3, wherein the first and
second sides of the gasket are each disposed transverse to at least
one of the rearward entrance side and forward exit side of the
sealing station, the first side having a first length, the first
operation zone extending less than the entire first length, the
second side having a second length, the first operation zone
extending less than the entire second length.
13. The sealing station according to claim 1, wherein first
operation zone is located nearer the rearward entrance side of the
sealing station than to the forward exit side of the sealing
station.
14. The sealing station according to claim 3, wherein the first and
second sides of the gasket are arranged substantially parallel to
one another with each of the first and second operation zones being
located nearer the rearward entrance side of the sealing station
than to the forward exit side of the sealing station.
15. A packaging machine comprising: a first feeding station for
supplying a first film in a forward direction of the packaging
machine; a second feeding station for supplying a second film in
the forward direction and above the first film; and a sealing
station that includes a lower tool and an upper tool, the lower
tool being configured to support the first film, in a first
arrangement the upper and lower tools are in contact with one
another, in a second arrangement the upper and lower tools are not
in contact with one another, the upper tool including a heating
surface and a gasket that is configured to urge the second film
against the first film when the upper and lower tools are in the
second arrangement, the gasket having a side with an operation
zone, the operation zone including notches that are separated by
trenches, the notches facing inward into a space delimited by the
gasket, the heating surface having a plurality of suction holes
that are configured to draw the second film towards the heating
surface when a suction is applied through the suction holes, the
notches and trenches of the first operation zone being configured
to cause the second film to be deformed inside the trenches in a
tensed state to inhibit or reduce the formation of creases in the
second film when the second film is drawn toward and heated by the
heating surface.
16. The packaging machine according to claim 15, further comprising
a pre-heating station located upstream from the sealing station in
the forward direction for pre-heating the second film before being
supplied to the sealing station, the sealing station having a
rearward entrance side and a forward exit side, the operation zone
being located nearer the rearward entrance side of the sealing
station than to the forward exit side of the sealing station.
17. The packaging machine according to claim 15, wherein the first
feeding station includes a cutting station upstream from the
sealing station in the forward direction, the cutting station
having a cutting tool that is suitable for generating at least one
opening in the first film, the sealing station comprising vacuum
means for applying a vacuum between the first and second films
through the at least one opening during the sealing of the first
and second films, the cutting tool being configured so that, or
arranged in the packaging machine such that the at least one
opening made in the first film coincides with a trench of the
operation zone of the gasket during the sealing of the first and
second films.
18. The packaging machine according to claim 17, wherein the
cutting tool is configured for making an opening for each of the
trenches of the operation zone of the gasket.
19. The packaging machine according to claim 17, wherein the
sealing station comprises at least one additional element arranged
in the lower tool that is configured for being introduced through
the at least one opening made by the cutting tool in the first
film.
20. The packaging machine according to any of claim 15, wherein the
first feeding station comprises a feeder supplying the first film
and a forming station downstream from the feeder in the forward
direction, the forming station being configured for sequentially
generate a plurality of cavities in the first film in the forward
direction, the packaging machine comprising a separating station
arranged downstream the sealing station in the forward direction
and configured for cutting the first and second films to generate
individual packages comprising a tray with a corresponding cavity
and a flap around the cavity, the forming station being configured
to form the cavity such that a width on the sides of the first film
extending from a lateral end of the cavity to an end of the first
film is left unformed, the sealing station being configured so that
the gasket is supported on the first and second films beyond the
flap, towards an outer side of the first and second films during
the sealing of the first and second films.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application relates to and claims the benefit and
priority to European Application No. EP16382497.2, filed Oct. 28,
2016.
TECHNICAL FIELD
[0002] The present invention relates to skin packaging machines, by
means of using a first film and a second film between which
products are packaged.
BACKGROUND
[0003] The use of skin packaging machines supplying a first film on
which products to be packaged are arranged and are then covered by
a second film adhered to the first film by means of applying heat
and pressure, for example, is well known. Packaging of this type is
known also as skin packaging because it uses two films that are
attached to one another around the contour of the product, one of
which takes the form of the product, and is disclosed, for example,
in patent document WO2015011076A1 belonging to the same
applicant.
[0004] The skin packaging of products is well known in the food
industry for packaging meats, fish, cheese, ready-made meals and
the like. During skin packaging, the product to be packaged is
usually placed on a first film or on trays previously formed in
said first film by way of supports in the packaging machine itself.
Then said supports, with the products on them, are arranged in a
sealing station, where they are covered with a second film. The
second film is generally pre-heated in the packaging machine before
being introduced in the sealing station to increase its deformation
capacity, and once it is arranged in the sealing station it is
brought towards the walls of the sealing station by vacuum for
greater heating and softening. Then the vacuum on the film is
released to cause the film to cover the entire product and adhere
to the surface of the support not covered by the product, thereby
forming a skin around the product and on the support.
[0005] In machines of this type, conveyor means generally guides
the bottom film along its entire path in the machine, and to that
end the conveyor means holds said bottom film and cause it to move.
A common way of holding said film is by means of clamps which
laterally hold and move the bottom film in the forward direction,
such that when said conveyor means moves forward (operated by a
chain, for example), the clamps drag the bottom film, causing it to
move forward.
[0006] Additionally, proximate to the holding surface of the
clamps, perforations are made in the bottom film that are used to
apply the vacuum between the top film and the bottom film through
same, such that the holding surface of the clamps is outside the
sealing station and the perforations are arranged inside the
sealing station, in the space where the products to be packaged are
located. When the top film is arranged on the bottom film in the
sealing station, pins are introduced through said perforations to
assure they are open and to generate a vacuum between both films,
while at the same time said pins tense the top film while it is
brought towards the walls of the sealing station, said tensing
being for preventing subsequent creasing. When the top film has
reached the suitable temperature in contact with the walls of the
sealing station, it is aerated or positive pressure is applied on
said top film, such that the vacuum generated between both films
makes it easier to seal the two films along the perimeter of the
product and cause the top film to adapt to the contour of the
product during the sealing operation. The perforated zone of the
bottom film is then separated from the rest of the bottom film and
disposed of. The same occurs with the part of the top film that is
arranged on said zone. This entails a considerable amount of
material to be disposed of (the zone held by the clamps and the
zone in which the holes have been made).
[0007] Patent document WO2014180823A1 discloses a packaging machine
which intends to minimize the material to be disposed of. To that
end, additional elements like those discussed above, for example,
for supporting the bottom film (or the top film) are not used in
the sealing station, such that it is not necessary to use excess
film on which these additional elements would act. Before the
sealing station, the bottom film is supported by conveyor means at
its ends (coinciding with the flaps of the final package or final
tray), and after the sealing station the conveyor means holds said
ends of the bottom film (now furthermore having the top film
adhered thereto) again. Although with this solution it is not
necessary to use additional material for supporting the films in
the sealing station, the fact that the films are not held in the
sealing station entails the need to use greater top film
thicknesses to achieve suitable sealing, makes it necessary to
perforate the inside of the package (the bottom film) to optimize
sealing between both films and prevent creases and/or bubbles, and
as the final package has been previously secured by its own flaps
means, said holding can mark or damage said final package, which is
not allowable and renders said solution to be unsuitable in many
cases.
SUMMARY OF THE DISCLOSURE
[0008] According to one embodiment a skin packaging machine is
provided that comprises a first feeding station for supplying a
first continuous film in a forward direction of the machine, a
second feeding station for supplying a second continuous film in
the forward direction and above the first film, and a sealing
station which is configured for receiving both films and comprising
an upper tool pressing on said films for sealing both films to one
another. The upper tool comprises: [0009] a closed holding contour
pressing on the films and delimiting the area of said films being
sealed to one another, [0010] a heating surface delimited by the
holding contour and facing said area corresponding to the second
film, [0011] heating means for heating the heating surface, and
[0012] suction means for bringing the second film towards said
heating surface for heating it.
[0013] The sealing station further comprises a sealing gasket
attached to the holding contour for preventing direct contact of
the upper tool with the films when said upper tool presses on them.
The sealing gasket comprises, on each side with respect to the
forward direction, an operation zone with a notched configuration
which is facing the space delimited by said sealing gasket, such
that when the second film is brought towards the heating surface
for heating, the second film tends to tense up towards the heating
surface in the notch-free areas of the operation zone, becoming
deformed, whereas the notches limit said deformation, thereby
preventing with said limitation early contact between said second
film, particularly in the zones of the notch-free area of the
sealing gasket, and said heating surface which could damage said
second film while at the same time certain deformation is allowed.
Particularly, deformation of the second film in a notch-free area
of the sealing gasket is limited by the notches of said sealing
gasket adjacent to said notch-free area. The notch-free areas
comprising trenches located between the notches in the operation
zone.
[0014] Therefore, when the second film is brought towards the
heating surface for being heated, said second film tends to tense
up as a result of the notched configuration of the sealing gasket
(particularly in the notch-free areas), becoming deformed, without
the need to incorporate additional elements to perform said tensing
up, whereas the actual configuration of the sealing gasket also
limits said deformation (as a result of the notches) for preventing
early contact between said second film and the heating surface of
the upper tool. Without this notched configuration of the sealing
gasket, the entire second film would tend to become deformed
towards the heating surface, without limitations and without
achieving suitable tension for preventing creases in the final
package, for which reason it would be necessary to include
additional elements such as pins, for example, which are inserted
through the first film for tensing up the second film, and said
additional elements would have to be arranged within the space
delimited by the holding contour, which would require increasing
said space, and therefore the area of the films delimited by said
holding contour, for generating packages of the same size.
[0015] Therefore, with the proposed solution the need to
incorporate said additional elements is eliminated, or should they
be needed due to the features of the second film, allows
incorporating said elements beneath the notch-free areas of the
sealing gasket, the area of the films necessary for one and the
same package size being reduced, the amount of material to be used
for one and the same package size therefore being reduced, with the
savings that this entails and the subsequent drop in packaging
process costs.
[0016] Since the process of deforming the second film requires
certain time in order to adapt to the contour of the sealing
station and to heat the area of the second film facing the heating
surface, the second film would in this case experience excess heat,
at least at the point where it first came into contact with the
heating surface, causing greater deformation of said point, which
could damage the film, which is a risk that has been avoided with
the proposed solution. Therefore, this drawback is solved without
additionally requiring the material of the second film to go beyond
the holding contour over the sides, the required material of the
second film being reduced and the amount of said second film to be
disposed of accordingly being reduced.
[0017] This solution is particularly furthermore advantageous the
thinner the second film is, because the less thick it is the more
ductile it will be as it heats up and is therefore brought towards
the heating surface more quickly, which would increase the risk of
early contact with the heating surface. Therefore, this solution
allows using less thick films acting like a second film, which also
reduces the amount of material used and the packaging process
cost.
[0018] These and other advantages and features will become evident
in view of the drawings and of the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a schematic view of a skin packaging machine
according to one embodiment.
[0020] FIG. 2a is a partial section view of an upper tool and a
lower tool of the sealing station of the machine of FIG. 1, tightly
holding the films between them during sealing, in which the second
film in the zone of a notch-free area of the sealing gasket is
depicted by means of a continuous line, and the same second film in
the zone of a notch of said sealing gasket is depicted by means of
a discontinuous line.
[0021] FIG. 2b is a partial, perspective, section view of an upper
tool and a lower tool of the sealing station of the machine of FIG.
1, tightly holding the films between them during sealing (the
second film is not depicted).
[0022] FIG. 2c is a side section view of the tools of the sealing
station of the machine of FIG. 1, tightly holding the films between
them during sealing (the second film is not depicted).
[0023] FIG. 3 shows a sealing gasket of the sealing station of the
machine of FIG. 1.
[0024] FIG. 4a shows a perspective view of a package generated in
the machine of FIG. 1, in the form of a tray, with a packaged
product.
[0025] FIG. 4b shows a side view of the tray of FIG. 4a, with the
packaged product.
DETAILED DESCRIPTION
[0026] FIG. 1 shows a schematic view of a skin packaging machine
100 according to one embodiment. The machine 100 is suitable for
packaging products P arranged between a first continuous film 10
and a second continuous film 20 sealed to one another around the
perimeter of the product P arranged between both by means of heat,
and these are then cut for generating individual packages with a
product P packaged therein. In some of the drawings the products P
are not depicted for the sake of clarity.
[0027] Continuous must be interpreted as the films 10 and 20 being
supplied without pre-cuts, i.e., without having been previously cut
to the sizes required for the final package. Therefore, the films
10 and 20 can be stored in the form of reels, for example, and can
be gradually unwound from the corresponding reel to be
supplied.
[0028] The machine 100 comprises a first feeding station 1 for
supplying the first continuous film 10 in a forward direction A of
the machine 100, a second feeding station 2 for supplying the
second continuous film 20 in the forward direction A and above the
first film 10, and a sealing station 3 which is configured for
receiving both films 10 and 20 in said forward direction A, with
the second film 20 above the first film 10, and for sealing them
together using heat. Previously, particularly before the first film
10 is fed into the sealing station 3, the products P to be packaged
are arranged on said first film 10 in a specific manner.
[0029] The skin packaging machines 100 works intermittently, one
sealing operation being performed in the sealing station 3 every
machine cycle. Once a cycle is performed and the films 10 and 20
are stationary, said films 10 and 20 are made to move in the
forward direction A a specific distance to perform a new machine
cycle. In every machine cycle, one product P is packaged in its
corresponding package in the sealing station 3, or a plurality of
products P can be packaged simultaneously (each one in a
corresponding package). For this last case, the products P are
arranged on the first film 10 before entering the sealing station
3, forming a line in the forward direction A (or a plurality of
parallel lines), a plurality of products P being located in the
sealing station 3 in one and the same machine cycle.
[0030] The sealing station 3 comprises an upper tool 3.1 depicted
in FIGS. 2a, 2b and 2c, pressing on the films 10 and 20 and being
supported on a lower tool 3.2 to apply said pressure, both films 10
and 20 being tightly held between both tools 3.1 and 3.2 during
sealing. The upper tool 3.1 comprises at least: [0031] one closed
holding contour 3.10 pressing on the films 10 and 20 during
sealing, and delimiting the area of said films 10 and 20 to be
sealed together in every cycle of the machine 100, [0032] one
heating surface 3.4 delimited by the holding contour 3.10 and
facing said area corresponding to the second film 20, [0033]
heating means (not depicted in the drawings) for heating the
heating surface 3.4, and [0034] suction means for bringing the
second film 20 towards said heating surface 3.4 for heating, said
heating surface 3.4 comprising a plurality of holes 3.41 that are
part of the suction means and through which said second film 20 is
brought towards said surface 3.4.
[0035] The suction means further comprise an actuator not depicted
in the drawings, causing said suction through said holes 3.41.
Suction means for this purpose in skin packaging machines 100 are
already known, so neither their operation nor their configuration
will be described in detail. Likewise, heating means are also known
and can be, for example, resistances configured for heating said
heating surface 3.4 when required.
[0036] The sealing station 3 further comprises a sealing gasket
3.12 which is attached to the holding contour 3.10 for preventing
direct contact of the upper tool 3.1 and the films 10 and 20 during
sealing, said films 10 and 20 therefore being protected from heat
in the holding contour 3.10, and this is shown by way of example in
FIG. 3. On the sides with respect to the forward direction A, the
sealing gasket 3.12 comprises an operation zone 3.5 with a notched
configuration which is facing the space delimited by said sealing
gasket 3.12, such that when the second film 20 is brought towards
the heating surface 3.4 for being heated, the second film 20 tends
to tense up through the notch-free areas 3.51 of the operation zone
3.5 towards the heating surface 3.4, becoming deformed, whereas the
notches 3.52 limit said deformation, thereby preventing early
contact between said second film 20 and said heating surface 3.4,
particularly in the zones of the notch-free area 3.51. The second
film 20 tenses up and becomes deformed through said notch-free
areas 3.51, and the notches 3.52 prevent early contact between said
deformed part of the second film 20 and the heating surface 3.4 in
the zone of the sealing station 3 that is arranged on the
notch-free areas 3.51, thereby preventing the second film 20 from
heating up too much in said zones prone to early contact, and due
to its ductility caused by a higher temperature, causing damage to
in the second film 20. According to some embodiments there are
provided two operation zones 3.5. According to some implementations
the operation zones 3.5 are the same and symmetrical with respect
to the forward direction A.
[0037] The operation zone 3.5 therefore comprises a succession of
notch-free areas 3.51 and of notches 3.52 distributed in the
forward direction A. According to some embodiments the distribution
of the notch-free areas 3.51 in the corresponding operation zone
3.5 and in the forward direction A is homogenous, the distribution
of the notches 3.52 in said operation zone 3.5 and in the forward
direction A therefore also being homogenous. According to some
embodiments the length of all the notch-free areas 3.51 is the same
in the forward direction A, and the length of the notches 3.52 is
also the same in the forward direction A, although the length of
one notch-free area 3.51 does not have to be the same length as one
notch 3.52. The value of lengths can depend on different factors,
such as the material, the properties or the thickness of the second
film 20, for example.
[0038] The length of the notch-free areas 3.51 and the length of
the notches 3.52 in the forward direction A are related to the
deformation to be applied on the second film 20 and to the
limitation of said deformation, respectively. The length of the
notch-free areas 3.51 is long enough to cause said deformation and
short enough to prevent early contact between said second film 20
and the heating surface 3.4. In turn, the length of the notches
3.52 is long enough to prevent early contact between said second
film 20 and the heating surface 3.4 and short enough to allow
deformation of the second film 20.
[0039] The width of the notch-free areas 3.51 and the width of the
notches 3.52 in a direction transverse to the forward direction A
are related to the deformation to be applied on the second film 20
and to the limitation of said deformation, respectively. The width
of the notch-free areas 3.51 is big enough to cause said
deformation and small enough to prevent early contact between said
second film 20 and the heating surface 3.4. In turn, the width of
the notches 3.52 is big enough to prevent early contact between
said second film 20 and the heating surface 3.4 and small enough to
allow deformation of the second film 20.
[0040] The thickness (height) of the sealing gasket 3.12 in the
zones corresponding with the notch-free areas 3.51 and the
thickness of said sealing gasket 3.12 in the zones corresponding
with the notches 3.52 are related to the deformation to be applied
on the second film 20 and to the limitation of said deformation,
respectively. The thickness in the zones corresponding with the
notch-free areas 3.51 is big enough to cause said deformation and
small enough to prevent early contact between said second film 20
and the heating surface 3.4. In turn, the thickness of said sealing
gasket 3.12 in the zones corresponding with the notches 3.52 is big
enough to prevent early contact between said second film 20 and the
heating surface 3.4 and small enough to allow the deformation of
the second film 20. Preferably, the thickness of the sealing gasket
3.12 is homogenous (the same) around its entire perimeter.
[0041] Preferably, the length, width and thickness of the sealing
gasket 3.12 in the zone corresponding with the notch-free areas
3.51 and the length, width and thickness of the sealing gasket in
the zone corresponding with the notches 3.52 are related to the
deformation to be applied on the second film 20 and to the
limitation of said deformation, respectively, and said lengths,
widths and thicknesses are related to one another to allow said
deformation and to prevent said early contact between the second
film 20 and the heating surface 3.4.
[0042] In some cases, the second film 20 can be exposed to a
heating process before entering the sealing station 3, in which
case the machine 100 comprises a pre-heating station (not depicted
in the drawings) with heating means, such as a heating plate for
example, arranged upstream from said sealing station 3 in the
forward direction A. The need for heating the second film 20 in the
sealing station 3 decreases as it starts from a higher temperature
in said sealing station 3 compared to the case in which it is
lacking said prior heating plate.
[0043] The films 10 and 20 are supplied in the forward direction A
intermittently, such that in every machine cycle a first specific
area of the second film 20 is exposed to the heat of the heating
plate and a second area of said second film 20 is sealed to the
first film 10 in the sealing station 3. In the following cycle,
said first area is arranged in the sealing station, becoming a
second area sealed to the first film 10. Due to the configuration
of the heating plate and the supply direction of the second film 20
to the zone where it is heated by said heating plate, the end that
is farthest downstream in the forward direction A of the second
film 20 is no longer heated before entering the sealing station 3,
such that it is shrink-wrapped and introduced in the sealing
station 3 with a lower temperature than the rest of the second film
20. In the following cycle, in which said end will be the end that
is farthest downstream in the forward direction A of the second
film 20 being sealed to the first film 10 in the sealing station 3,
said end is less hot and has a lower risk of adhering to the
heating surface 3.4, and it also has a lower risk of creased being
generated therein due to the shrink-wrapping process to which it
was previously subjected. The higher the temperature of the second
film 20, the more ductile it is, such that since said end is at a
lower temperature, the rest of the second film 20 is more ductile
and more easily and more quickly brought towards the heating
surface 3.4, for which reason there is no risk of said end adhering
to said heating surface 3.4 too soon.
[0044] For this reason, for these cases each operation zone 3.5 of
the sealing gasket 3.12 can comprise a length that is smaller than
the total length of said sealing gasket 3.12, each operation zone
3.5 extending in the forward direction A from the entrance into the
sealing station 3 to a specific intermediate point. The operation
zone 3.5 of the sealing gasket 3.12 therefore corresponds with the
zone of the sealing station 3 where the second film 20 is provided
with a higher initial temperature. As a result, the zone of the
sealing gasket 3.12 associated with the less hot end of the area of
the second film 20 to be sealed to the first film 10 in the sealing
station 3 is not notched, but nevertheless since it is less hot, it
does not present the risk of adhering to the heating surface 3.4
when not wanted, and since it was previously subjected to a
shrink-wrapping process, the risk of generating creases in the
package is eliminated.
[0045] In the embodiment of the machine 100 shown in the drawings,
the first feeding station 1 comprises a cutting station 13 upstream
from the sealing station 3 in the forward direction A, with at
least one cutting tool which is suitable for generating at least
one opening (not depicted in the drawings) in the first film 10, to
later in the sealing station 3 generate a vacuum in the space
existing between the area of the two films 10 and 20 delimited by
the holding contour 3.10. If a plurality of products P is going to
be simultaneously packaged in the sealing station 3, each one in
its own package, this opening serves to generate a simultaneous
vacuum in all the packages. Naturally, if instead of one opening
more openings are made (both if only one product P is packaged and
if a plurality of products P is simultaneously packaged), the
vacuum is generated more quickly, and in some cases more
efficiently. The sealing station 3 therefore receives the first
film 10 with said opening and comprises vacuum means (not depicted
in the drawings) for applying a vacuum between the two films 10 and
20 through said opening (in the mentioned space), during the
sealing of said films 10 and 20, such that the product P arranged
in said space is vacuum packaged.
[0046] The cutting tool is configured such that, or arranged such
that in the machine 100 such that, the opening made on the first
film 10 coincides with a notch-free area 3.51 of the operation zone
3.5 of the sealing gasket 3.12 of the sealing station 3 during the
sealing of the two films 10 and 20. The aforementioned vacuum is
thereby generated without having to make the opening at a point
that will pertain to the final package and would therefore have to
comply with a series of requirements (closed later) and would
affect the appearance of the package. Furthermore, unlike what
occurs in the prior art where to generate said vacuum without the
necessary opening affecting the final package, said opening is made
on the sides of the films 10 and 20 outside the holding contour
3.10; here, said films 10 and 20 do not required being acted on
beyond said holding contour 3.10, and it is therefore not necessary
to increase the width of said films 10 and 20 beyond said holding
contour 3.10 for this purpose. This allows reducing the generated
remnant 60 of the films 10 and 20, remnant 60 being understood as
the material from said films 10 and 20 that is subsequently
eliminated or disposed of, with the subsequent material and cost
savings. Preferably, the remnant 60 is collected in a collecting
station 6.
[0047] According to some embodiments the cutting tool is configured
for making an opening for each of the notch-free areas 3.51 of the
operation zone 3.5 of the sealing gasket 3.12 of the sealing
station 3, although it is sometimes not necessary to make one
opening for each of the notch-free areas 3.51.
[0048] In the embodiment of the machine 100 shown in the drawings,
the final packages in which the products P are packaged can be
trays 4 covered by a cover film. The trays 4 are generated from the
first film 10, and the cover film is generated from the second film
20. Each tray 4 comprises a base 40 on which the product P is
arranged, a flap 41 surrounding the base 40 at a different height
and a wall 42 joining the flap 41 with the base 40, as depicted by
way of example in FIGS. 4a and 4b, which show a final package (in
the form of a tray) with a packaged product P. Therefore, in said
embodiment the first feeding station 1 comprises a feeder 11
supplying the first continuous film 10 from a reel of film for
example, and a forming station 12 downstream from the feeder 11 in
the forward direction A. The forming station 12 is configured for
generating a plurality of cavities 15 in the first film 10 in the
forward direction A, as the first film 10 moves forward in said
forward direction A, in one or more parallel lines, each cavity 15
being associated with a tray 4. The sealing station 3 is downstream
from the forming station 12 in the forward direction A, such that
said sealing station 3 receives said first film 10 already formed
(with the cavities 15). The cutting tool is preferably upstream
from the forming station 12 in the forward direction A, but it
could also be downstream from the forming station 12, between said
forming station 12 and the sealing station 3, in said forward
direction A.
[0049] In the embodiment shown in the drawings, the machine 100
further comprises a separating station 5 arranged downstream from
the sealing station 3 in the forward direction A, and configured
for cutting the films 10 and 20 already sealed to one another and
with the product P therein, thereby generating individual packages
(each with its corresponding product P). The transverse and/or
longitudinal cuts required for obtaining individual packages,
depending on how the products P are packaged (in a single line in
the forward direction A or in a plurality of parallel lines) are
made in the separating station 5.
[0050] Each final package therefore comprises a tray 4 like the one
discussed above (in the particular case that the final packages are
of the tray type), with a cavity 15 and a flap 41 around said
cavity 15. The forming station 12 is configured for forming a
cavity 15 such that a width of the first film 10 extending from the
lateral end of the first film 10 to the lateral end of said
cavities 15 is left unformed, and the sealing station 3 is
configured so that the sealing gasket 3.12 is supported on said
non-formed zone for sealing the two films 10 and 20 to one another.
Particularly, the sealing gasket 3.12 is supported on a part of
said non-formed zone that is located more outwardly than the part
that will later be the flap 41 of the corresponding tray 4. Acting
on a zone of the films 10 and 20 that will later become part of an
individual package, i.e., the flap 41, is avoided, which prevents
marking said flap 41. In some cases, the zone that will become the
flap 41 of a final tray 4 is also formed, so in these cases the
sealing gasket 3.12 is supported on the non-formed zone. Therefore,
in the embodiment shown in the drawings the configuration of the
holding contour 3.10 and the configuration of the forming station
12 are related and comply with related parameters for the correct
packaging of products P in said machine 100. Furthermore, the
opening (or openings) made by the cutting tool is also located
outside the flap of each tray 4, such that the vacuum of the
package can be generated without the appearance of the tray 4 being
affected as a result.
[0051] Additionally, the sealing station 3 can comprise additional
elements not depicted in the drawings in the form of pins, for
example, to assure the opening of the openings of the first film 10
while generating the vacuum between the first film 10 and the
second film 20, and/or to tense up the second film 20 as it is
brought towards the heating surface 3.4. Said additional elements
are arranged in the lower tool 3.2 of the sealing station 3 below
the notch-free areas 3.51 of the sealing gasket 3.12 of the upper
tool 3.1, such that they are introduced through the openings of the
first film 10 in the space of the notch-free areas 3.51 of the
sealing gasket 3.12 and perform their function without generating a
larger amount of remnant 60 of films 10 and 20.
* * * * *