U.S. patent application number 12/882638 was filed with the patent office on 2011-03-17 for packaging machine with several heater elements.
This patent application is currently assigned to MULTIVAC SEPP HAGGENMULLER GMBH & CO. KG. Invention is credited to Elmar Ehrmann.
Application Number | 20110061344 12/882638 |
Document ID | / |
Family ID | 42989684 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110061344 |
Kind Code |
A1 |
Ehrmann; Elmar |
March 17, 2011 |
PACKAGING MACHINE WITH SEVERAL HEATER ELEMENTS
Abstract
The disclosure relates to a packaging machine and a method, in
particular for an intermittently operating deep-draw packaging
machine, which has at least one heating surface with a plurality of
heater elements, which can be individually controlled by a
controller in order to heat a film to different temperature levels.
The heater elements are formed as thick-film heater elements
Inventors: |
Ehrmann; Elmar; (Bad
Gronenbach, DE) |
Assignee: |
MULTIVAC SEPP HAGGENMULLER GMBH
& CO. KG
Wolfertschwenden
DE
|
Family ID: |
42989684 |
Appl. No.: |
12/882638 |
Filed: |
September 15, 2010 |
Current U.S.
Class: |
53/453 ;
53/561 |
Current CPC
Class: |
B29C 2793/009 20130101;
B29C 51/46 20130101; B29C 51/04 20130101; B29C 51/422 20130101;
B29C 2793/0063 20130101; B29C 2793/0036 20130101; B29C 51/426
20130101; B29C 51/266 20130101; B29C 2793/0045 20130101; B29C
51/303 20130101; B29C 51/445 20130101 |
Class at
Publication: |
53/453 ;
53/561 |
International
Class: |
B65B 47/02 20060101
B65B047/02; B65B 47/00 20060101 B65B047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2009 |
DE |
10 2009 041 563.7 |
Claims
1. A packaging machine comprising: a moulding station having at
least one heating surface with a plurality of heater elements per
heating surface; and a controller configured to individually
control the heater elements in order to bring different regions of
a film to different temperature levels; wherein the heater elements
are formed as thick-film heater elements.
2. A packaging machine according to claim 1 wherein the at least
one heating surface is configured as a heating plate, a stamp
and/or surfaces of a moulding cavity.
3. A packaging machine according to claim 1 wherein the heater
elements are integrated into a common heating plate or heating
mat.
4. A packaging machine according to claim 1 wherein that at least
one heating surface comprises two mutually facing heating surfaces,
and wherein the heater elements arranged on one heating surface are
mirrored with the heater elements on the other heating surface.
5. A packaging machine according to claim 1 wherein the at least
one heating surface comprises a plurality of heating surfaces that
can be heated independently of one another.
6. A packaging machine according to claim 1 wherein the moulding
station is configured to perform a moulding process on the film,
and wherein the at least one heating surface is coolable during the
moulding process.
7. A packaging machine according to claim 1 wherein the packaging
machine is implemented as a deep-draw packaging machine with an
intermittent operational cycle.
8. A packaging machine according to claim 1 wherein the film is a
plastic film.
9. A method for an intermittently operating a deep-draw packaging
machine with a moulding station, the method comprising: feeding a
film into the moulding station, wherein the moulding station
comprises at least one heating surface with a plurality of heater
elements formed as thick-film heater elements, wherein the heater
elements are controllable individually by a controller in order to
heat the film to different temperature levels; closing the moulding
station to create a tightly closed chamber; controlling the heater
elements with the controller for a spatially inhomogeneous
temperature distribution in the film; positioning the film on the
heater elements; switching off the heater elements after reaching
the different temperature levels in the film; deforming the film in
a mould tool part of the moulding station; cooling the film in a
stable and no longer plastically deformable temperature range;
opening the moulding station; and removing the deformed film from
the moulding station.
10. A method according to claim 9 wherein the at least one heating
surface comprises at least two mutually facing heating surfaces on
which the heater elements are in each case mirrored with respect to
one another, wherein in each case two mutually facing heater
elements are operated together on the oppositely situated heating
surfaces.
11. A method according to 9 wherein the at least one heating
surface comprises a plurality of heating surfaces, of which at a
point in time only one is heated at least progressively.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims foreign priority benefits under 35
U.S.C. .sctn.119(a)-(d) to German patent application number DE
102009041563.7, filed Sep. 15, 2009, which is incorporated by
reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a packaging machine and
method for heating of a film to be deformed.
BACKGROUND
[0003] From the state of the art, deep-draw packaging machines are
known which have a moulding station in which a film is heated by
means of a heating plate such that it can then be formed into a
cavity in the lower part of the mould tool. The process must take
place very quickly, because on one hand due to the generally cooler
compressed air, which is initially present over the complete
surface of the upper part of the mould tool, the film is cooled,
and on the other hand in the upper regions of the side walls and in
the region of the bottom of the mould cavity in the lower part of
the mould tool the film can become so cold during the moulding
process that subsequent deformation of the film leads to an
undesirable or too thin wall thickness, or adequate forming in the
whole region of the cavity is no longer possible, because the film
has cooled below the temperature required for plastic
deformation.
[0004] Above all, with large deep-drawing depths and small radii in
the region of the cavity bottom, there is a great risk that the
wall thickness of the film after deformation is too different and
these cavities must no longer be used for quality reasons and have
to be extracted.
[0005] In order to be able to individually heat the film before the
moulding process, zone heaters can be employed in which the heating
plate has been manufactured according to the cavity shape so that
different regions of the film are heated differently in order to
obtain a uniform wall thickness of the film in the subsequent
process. This embodiment is constructively very elaborate and
extremely inflexible, because it is linked to the package
shape.
[0006] From JP 55095519, U.S. Pat. No. 5,280,434, DE 102006045327
and GB 1405753 heating devices are known with which a heating
surface has a large number of heater elements which can be
controlled individually to be able to generate different
temperatures on the individual heater elements. The known
embodiments are not suitable for also fitting to a moulding stamp
nor to moulding surfaces of a lower part of a mould tool such as
side walls and bottom surface in order to generate different
temperatures in these regions and thus to be able to positively
influence the moulding process.
[0007] In the application DE 102009030508.4, which has not yet been
published, a further alternative technique is described. Here, in a
film to be deformed, a spatially inhomogeneous temperature
distribution is produced so that the film is optimally prepared
according to the requirements of the moulding process. This is
preferably however realised by a simple continuously heated heating
plate and special properties of the film.
[0008] A further disadvantage of the state of the art is a
continuously heated heating plate with a simultaneously cooled
upper part of the mould tool. In order to be able to apply the
required heat energy to the film for moulding the film and
simultaneously to be able to maintain the general processing times
in the deep-draw packaging machine short for a high machine
capacity, the heating plate is continuously at the necessary
temperature, which is transferred to the film at the moment of
feeding or heating the film for an appropriate time in the moulding
station. These high temperatures of over 100.degree. C. require
cooling of the upper part of the mould tool above the heating plate
to provide protection against injuring the operating personnel
through burning by touching the relatively freely accessible upper
part of the mould tool.
[0009] This high energy storage in the heating plate also has
disadvantages in the heating up phase, for example after a tool
change, and in a waiting period before renewed setting up in the
region of the moulding station due to the necessity of the heating
plate having to cool down.
[0010] From DE 102005043026 a reference is known from the field of
household appliances to a possible use of a thick-film heater for
heating up water. Here, the economical manufacture and the low
space requirement should offer advantages.
SUMMARY
[0011] An object of the present disclosure is to provide a device
which is suitable for heating a film individually with different
temperature levels taking into account in this respect the energy
consumption required for the moulding process and eliminating the
disadvantages of the state of the art.
[0012] For the purpose of the disclosure, "thick-film heating" is
taken to mean heating in which the heater elements (without
substrate or carrier) have a thickness of at least 1 .mu.m. The
term "heater element" is used synonymously with "heating
circuit".
[0013] The embodiment of the heating surface according to this
disclosure has the advantage that due to the low proportion of
material the thick-film heaters can be heated quickly to the
required temperature and are able to cool down to the ambient
temperature just as quickly, because there is no accumulation of
heat. In conjunction with a controller this facilitates a
temporally limited switch-on period of the thick-film heater
elements during which the film is to be heated, and thus low energy
consumption.
[0014] Due to a uniform distribution of a plurality of thick-film
heaters, a high flexibility with regard to different package shapes
is also produced.
[0015] The plurality of heater elements, preferably distributed on
the heating surface uniformly or in matrix form, can heat a film
individually through the individual control of the heater elements
such that different regions or areas of the film can be heated to
various levels. This leads to different temperature levels, which
can be produced appropriately to the subsequent moulding process in
order to obtain the desired wall thicknesses and deformations of
the moulded cavity during or after the moulding process.
[0016] Above all with moulding processes with large deep-drawing
depths, small radii and thin films the packaging machine according
to the invention presents a solution, which offers a more
favourable solution in terms of energy than the state of the art
and which ensures increased process reliability and thus attainment
of the quality of the packaging cavity.
[0017] For the usual necessity of being able to produce different
cavity shapes on one and the same deep-draw packaging machine the
heating device according to the invention is found to be an
economical solution, because no elaborate components have to be
made available specially for the moulding process nor set up during
a change of product, and because the individually produced
temperature levels, which are necessary for the film, can be saved
in the controller and recalled. This can lead to the shortest
changeover times. Also changes to the different temperature levels
are possible via the controller in order to be able to match
varying boundary conditions in the moulding process. These boundary
conditions may be, for example, shorter operating cycles or varying
film thicknesses.
[0018] The thick-film technology facilitates integration of a
plurality of heater elements in a common layer, which can be fitted
on a carrier plate and thus be formed as a heating plate.
Preferably, a flat arrangement of this nature can be fitted in an
upper part of the mould tool or can preheat the films as a
preheater above and/or below the film before the moulding station
if the time available in the moulding station is not
sufficient.
[0019] It is conceivable to fit the heater elements individually
and to realise them individually or collectively connected to the
controller. On a display assigned to the controller the temperature
levels can be individually entered, saved and/or specified and fed
into the packaging machine from outside in dependence of the heater
elements present.
[0020] During the moulding process, with the initial contact of the
film with a stamp or the surfaces of the moulding cavity in the
lower part of the mould tool, rapid cooling of the film may occur
in these partial regions. The consequence of this may be that the
film in these partial regions can no longer extend sufficiently and
the wall thickness of the film in the remaining regions reduces
excessively. This undesired behaviour during the moulding process
can be countered with the packaging machine according to the
invention, if in addition or alternatively heating surfaces are
fitted at least partially on the stamp or on the walls and/or
bottom of the moulding cavity. Thus, the film can be maintained
deformable also in these partial regions through a specific
temperature level for as long as is necessary for the moulding
process.
[0021] The embodiment as a thick-film heater offers the advantage
of cooling the heater elements in the shortest time through cooling
in the region of the moulding cavity, for example by means of
cooling water channels, such that the heater elements assume the
temperature of the cooled moulding cavity or of the lower part of
the mould tool and thus this hardly delays the cooling process of
the deep-drawn film.
[0022] The use of the packaging machine according to the invention
is particularly practicable in an intermittently operating
deep-draw packaging machine, because here the time for an
operational cycle, also of the sealing station in the manufacture
of packaging under a modified atmosphere, is influenced and in this
respect an unwanted dwell time of the film in the moulding station
and heating device can occur. The described problem can be avoided
by the thick-film heaters which are switched off during this
period.
[0023] The packaging machine according to the invention has a
further positive effect during the use and processing of plastic
films, which are mostly multi-layered and in line with their
properties should therefore be heated very individually for the
moulding process in order to be able to obtain the desired
results.
[0024] The methodical sequence according to the invention with an
intermittently operating deep-draw packaging machine with at least
one heating surface, which has a plurality of preferably uniformly
distributed thick-film heaters, whereby a controller can
individually control these thick-film heaters, primarily has
advantages when heating a film to be deformed to different
temperature levels.
[0025] At the start of an operational cycle the moulding station of
the deep-draw packaging machine is fed with the film in the form of
a strip-shaped material by means of a feed system via gripper
chains arranged on both sides. Then the moulding station is closed
and a closed chamber is created. The controller can meanwhile, or
also only after the closure of the moulding station, control and
heat up the heater elements which are realised as thick-film heater
elements. This control can be implemented according to a program
saved in the memory of the controller or can occur through entries
fed into the controller by the operating personnel.
[0026] In order to introduce the heat energy into the film, the
film is preferably drawn onto the heater elements by a negative
pressure in the upper part of the mould tool, so that the film is
located uniformly on the heater elements. The film heats up
accordingly and the desired individual temperature levels arise
within the film.
[0027] The controller switches off the heater elements once the
film moulding process starts and the film is deformed into the
lower part of the mould tool by means of compressed air in the
upper part of the mould tool and/or negative pressure in the lower
part of the mould tool.
[0028] The process is terminated when the film has cooled to a
"stable" temperature range in which it is no longer deformable.
[0029] Then the moulding station opens and with the removal of the
moulded cavities the next section of the film is introduced into
the moulding station.
[0030] Due to a possible cycle lengthened by the sealing station,
there may be waiting periods, for example during cooling of the
film in the lower part of the mould tool and/or on opening the
moulding station.
[0031] In the following, an advantageous embodiment of the
disclosure is explained in more detail with reference to the below
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a schematic side view of a packaging machine
according to the disclosure in the form of a deep-draw packaging
machine;
[0033] FIG. 2 is a schematic vertical section through the moulding
station with preheating station of the packaging machine shown in
FIG. 1 in opened position;
[0034] FIG. 3a is a schematic view of the moulding station shown in
FIG. 2 in closed position with the moulding process starting;
[0035] FIG. 3b is a schematic view of the moulding station shown in
FIG. 2 in closed position during the moulding process;
[0036] FIG. 3c is a schematic view of the moulding station shown in
FIG. 2 in closed position with the moulding process finished;
[0037] FIG. 3d is a schematic view of the moulding station shown in
FIG. 2 in open position and with the moulding process finished;
[0038] FIG. 4a is a schematic plan view of the film, the heater
elements and the various heating regions;
[0039] FIG. 4b is a graphical representation of the temperature
distribution in the film in section IV-IV in FIG. 4a;
[0040] FIG. 5 is a schematic view of the moulding station shown in
FIG. 2 in closed position in a variant with heater elements in the
moulding cavity; and
[0041] FIG. 6 is a schematic view of the moulding station shown in
FIG. 2 in closed position in a variant with heater elements on a
stamp.
DETAILED DESCRIPTION
[0042] In the figures identical components are designated with the
same reference numerals throughout.
[0043] FIG. 1 shows a schematic view of a packaging machine 1
according to the disclosure in the form of a deep-draw packaging
machine. This deep-draw packaging machine 1 has a moulding station
2, a sealing station 3, a transverse cutting device 4 and a
longitudinal cutting device 5 which are arranged in this order in
the working direction R on a machine frame 6. At the input end on
the machine frame 6 there is a feed roll 7 from which a film 8 is
pulled off. In the region of the sealing station 3 a material store
9 is provided from which a lid film 10 is pulled off. At the output
end on the packaging machine a removal device 13 in the form of a
conveyor belt is provided with which finished, singled-out packages
can be taken away. Furthermore, the packaging machine 1 has a feed
device, which is not shown and which grips the film 8 to transport
it further in the working direction R during each main operating
cycle. The feed device can, for example, be realised using
transport chains arranged on both sides.
[0044] In the illustrated embodiment the moulding station 2 is
formed as a deep-drawing station with which cavities 14 can be
formed in the film 8 by deep drawing. Here, the moulding station 2
can be formed such that several cavities can be formed adjacent to
one another in the direction perpendicular to the working direction
R. In the working direction R behind the moulding station 2 an
insertion section 15 is provided in which the cavities 14 formed in
the film 8 are filled with the product 16.
[0045] The sealing station 3 has a closable chamber 17 in which the
atmosphere in the cavities 14 can be replaced, for example, by gas
flushing with a replacement gas or with a gas mixture before
sealing.
[0046] The transverse cutting device 4 is formed as a punch which
parts the film 8 and the lid film 10 in a direction transverse to
the working direction R between adjacent cavities 14. Here, the
transverse cutting device 4 operates such that the film 8 is not
parted over the complete width, but rather is not parted at least
in a marginal region. This facilitates controlled further transport
by the feed device.
[0047] In the illustrated embodiment the longitudinal cutting
device 5 is formed as a cutter arrangement with which the film 8
and the lid film 10 are parted between adjacent cavities 14 and on
the side edge of the film 8 so that singled-out packages are
available behind the longitudinal cutting device 5.
[0048] The packaging machine 1 also has a controller 18. It has the
task of controlling and monitoring the processes running in the
packaging machine 1. A display device 19 with the operating
elements 20 is used for visualising or influencing the process
sequences in the packaging machine 1 for, respectively by, an
operator.
[0049] The general principle of operation of the packaging machine
1 is briefly described in the following.
[0050] The film 8 is pulled off the feed roll 7 and transported
through the feed device into the moulding station 2. In the
moulding station 2 cavities 14 are formed in the film 8 by deep
drawing. The cavities 14 are transported further together with the
surrounding region of the film 8 in a main operating cycle to the
insertion section 15 in which they are filled with the product
16.
[0051] Then the filled cavities 14 are transported into the sealing
station 3 by the feed device in the main operating cycle together
with the surrounding region of the film 8. The lid film 10 is
transported further with the feeding movement of the film 8 after a
process of sealing onto the film 8. Here the lid film 10 is pulled
from the material store 9. By sealing the lid film 10 onto the
cavities 14 closed packages are created which are transported
singled-out into the following cutting processes 4 and 5 and
transported out of the packaging machine by means of the removal
device 13.
[0052] FIG. 2 illustrates a moulding station 2 with a preceding
preheating station 21 in a variant with a preheater 22 arranged
above and also a preheater 23 arranged below. This configuration is
practicable primarily with thick films 8, because the time duration
for the heating of the film 8 only in the moulding station 2 is so
large that the resulting time of an operational cycle can extend
unnecessarily and thus the capacity of the packaging machine 1 can
be reduced in terms of the production of packages per minute.
[0053] The moulding station 2 comprises a lower part of the mould
tool 24 with the moulding cavities 25. The lower part of the mould
tool 24 is implemented for movement upwards and downwards via a
lifting gear which is not illustrated. Furthermore, the moulding
station 2 comprises an upper part of the mould tool 26 in which a
heating plate 27 is fitted to the underside. On the heating plate
27 a plurality of uniformly distributed heater elements 28 are
arranged, implemented as thick-film heating. The individual heater
elements 28 can be controlled via the controller 18, and the
visualisation or the adaptation of the individual temperature
levels of the heater elements 28 can be realised via the display
device 19.
[0054] The heating of the film 8 can occur with the moulding
station 2 still open, during the closing process or only when the
moulding station 2 is closed.
[0055] In FIG. 3a the lower part of the mould tool 24 has been
moved up and now forms a closed chamber 17 with the upper part of
the mould tool 26. At the same time the film 8 is clamped all
around at the edge by means of a seal 11 and by the lower part of
the mould tool 24 and the upper part of the mould tool 26 and is
tightly closed. Once the film 8 has been heated individually to the
desired temperature by means of the individual heater elements 28,
the controller 18 switches the heater elements 28 off and the
moulding process starts in the form of deep drawing by overpressure
above the film 8 and/or negative pressure below the film 8. Here,
the film 8 initially forms a type of sack due to the pressure
difference and the forces acting uniformly on the film 8.
[0056] In FIG. 3b the film 8 has reached the bottom 29 of the
moulding cavity 25 and also contacts the moulding cavity 25 in the
upper region of the side walls 30. These surfaces have a very much
lower temperature than the film 8 so that here the film 8 is
cooled. In order that the film 8 does not cool down below the
temperature for the plastic deformation in the moulding time
remaining, these regions 29 and 30 of the film 8 are heated to a
higher temperature level than the other regions.
[0057] In the further course of the moulding process the film 8 is
extended further until the film 8 lies completely in the moulding
cavity 25, as illustrated in FIG. 3c. When the film 8 has cooled
down so much that the moulded cavity 14 is stable, the moulding
station 2 opens with the lower part of the mould tool 24 moving
downwards, as illustrated in FIG. 3d.
[0058] In the plan view FIG. 4a shows the heating surface of the
heating plate 27 with grid or matrix shaped, closely contacting
heater elements 28 and four regions 31 to 34. The graph in FIG. 4b
shows the four different temperature levels 31' to 34' distributed
over the heating surface, which arise due to the different
temperatures of the heater elements 28 in the regions 31 to 34.
[0059] In FIG. 5 a variant of the packaging machine 1 according to
the present disclosure is shown in which, in addition to the
heating surface on the upper part of the mould tool 26, further
heating surfaces 35 and 36 are fitted to the walls and bottom of
the moulding cavity 25.
[0060] As another variant, an embodiment of stamp deformation is
illustrated in FIG. 6. On the stamp 37 the surfaces which are in
contact with the film 8 have heater elements 28 fitted which ensure
individual temperature levels in these regions.
[0061] The heating surfaces of the packaging machine according to
the invention are not restricted to the illustrated embodiments,
but rather other combinations or regions can be implemented in the
moulding station with heater elements.
[0062] For controlling individual temperature levels it is also
conceivable that with many small heater elements 28 they are not
all controlled individually, but rather in groups by the controller
18.
[0063] The film 8 can comprise a plastic film, another
thermoformable material or a combination of materials.
[0064] The packaging machine 1 according to the invention also
comprises a moulding station 2 for a lid film in order to
individually heat it and deform it before sealing with the film
8.
[0065] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *