Note: Descriptions are shown in the official language in which they were submitted.
Sealing apparatus and method for sealing packages
The invention relates to a sealing apparatus for
sealing packages of the generic type specified in the
preamble of claim 1, and to a method for sealing
packages by means of an apparatus of said type.
Washing or dishwashing agents for household use are
increasingly packaged in the form of powders or liquids
in water-soluble packages. The packages are composed of
a water-soluble foil and contain a filling of one unit
dose of the washing or dishwashing agent. The filled
and sealed package unit is placed into the washing
machine or dishwasher. Upon contact with water, the
foil package dissolves and releases the content in the
provided quantity.
In the production of such a package, a base foil and a
cover foil are used, wherein the base foil and the
cover foil are formed from a water-soluble foil web.
Normally, the base foil is deep-drawn into
corresponding dies under the action of heat and vacuum.
As a result of the forming process, depressions form in
the base foil, which depressions are filled with the
filling. A cover foil is subsequently sealed onto the
base foil. By means of the sealing of the two foils,
the filling situated in the molds is enclosed. Finally,
the sealed package units are cut out of the coherent
foil webs, such that said package units can be used
individually by the user.
For the sealing of such packages, use is made not only
of the hot-sealing method such as is known per se for
foils but also of a water-based sealing. In the case of
water-based sealing, water is applied to the cover foil
by means of a moistening unit, for example with a felt
roller. The moistened felt roller rolls on the water-
soluble foil web, whereby the surface of said foil web
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is dissolved. The cover foil with dissolved surface is
then pressed by means of a pressing device onto the
prepared base foil, wherein the dissolution of the foil
surface gives rise to a sealing action.
A disadvantage of such water-based sealing methods is
that the quantity of water applied by means of the felt
roller can be only poorly metered. If the quantity of
water applied to the water-soluble foil is too great,
excessive dissolution of the foil occurs, resulting in
an undesired reduction in the foil thickness. As a
result, during the further course of production, the
foil or, later, the individual packages can tear.
However, if the quantity of water applied is too small,
sufficient dissolution of the foil surface does not
occur, such that the two foils do not properly connect.
The packages can consequently develop leaks. However,
even if succeeds in setting and maintaining a suitable
applied quantity of water during ongoing operation, an
adaptation to changed conditions can be realized only
with difficulty. Saturation is observed on the
application roller or felt roller, which leads to a
change in the applied quantity and also to
contamination of the roller during the course of the
production process. This results in an impairment of
the sealing action. Frequent machine shutdowns for the
purposes of exchanging the roller are inevitable.
In particular in the event of an interruption in
production, overmoistening commonly occurs because the
foil web is advanced no further and is thus in lasting
contact with the felt roller, with an unchanging
contact zone. The resulting undesirably large transfer
of liquid to the foil web and the mechanical contact
with the felt roller lead to dissolution and subsequent
tearing of the cover foil. Even if this can be
prevented, it is not possible for prepared, possibly
filled but not yet sealed packages to be fully sealed
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after a standstill, because the applied liquid dries
out during the standstill period. Undesired waste is
generated. Furthermore, the non-sealed filling can
contaminate the apparatus, such that cumbersome
cleaning work must be performed.
The invention is based on the object of further
developing a generic sealing apparatus such that an
improved application of liquid to the water-soluble
foil web is achieved.
Said object is achieved by means of a sealing apparatus
having the features of claim 1.
The invention is furthermore based on the object of
specifying a method for sealing packages, by means of
which method moistening of the water-soluble foil web
can be performed in a more effectively metered manner.
Said object is achieved by means of a method having the
features of claim 8.
According to the invention, it is provided that the
moistening unit of the sealing apparatus is formed as a
spraying device for contactlessly spraying the liquid
onto the water-soluble foil web and is positioned at a
distance from the water-soluble foil web. In the
associated method, the water-soluble foil web is
firstly supplied to the apparatus, wherein a base foil
and/or a cover foil of the package are formed from the
water-soluble foil web. Subsequently, by means of the
spraying device, which is positioned at a distance from
the water-soluble foil web, water-containing liquid is
sprayed onto the water-soluble foil web. The cover foil
is led onto the base foil and is pressed and sealed
together with said base foil, in the state in which
they are wetted with the liquid, by means of a pressing
device.
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The invention is based on the underlying concept
whereby mechanical contact between the foil and the
moistening unit is omitted, and instead, the water-
containing liquid provided for dissolving the foil
surface is applied contactlessly. The application of
the liquid can, by means of the spraying device, be set
with regard to flow rate and areal distribution with
such precision and repeatability that the desired
degree of surface dissolution is exactly achieved, and
consequently uniform sealing occurs along the entire
foil surface. It is thus also easily possible to react
to changed boundary conditions, such as for example
batch fluctuations in foil thickness or the like, in
the production process. A further advantage consists in
that the moistening unit is not in direct contact with
the cover foil, such that mechanical impairment is
avoided. Whereas, in the prior art, the conveying speed
of the foil fixedly predefines the speed of rotation of
the felt roller rolling thereon and thus makes control
or adaptation of the supply of water very difficult, it
is possible in the case of the invention for the
delivery rate of the spraying device to be adjusted
entirely independently of the movement of the foil.
Accordingly, for example in the event of an
interruption in production, it is also possible for the
spraying process and thus the moistening of the foil to
be easily stopped, without the cover foil excessively
thinning, or even tearing, in the presence of an
excessively high liquid quantity. The resumption of
operation can be performed without exchanging the
foils. This also includes the possibility whereby
package units that were prepared but not yet sealed
during the prior shutdown can be fully sealed without
waste being generated. The risk of machine
contamination is reduced.
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According to the invention, the spraying device
comprises an electromechanical spraying system with a
row of outlet nozzles for contactlessly spraying the
liquid onto the water-soluble foil web. This may
involve a bubble-jet or piezo print head known, for
example, from inkjet print heads. It however preferably
involves an electromechanical spraying system with
solenoid valves, whereby water or water-containing
liquids can be applied to the foil web in a high-
quality manner in a suitable quantity, at a suitable
speed, and in a suitable distribution, by means of a
suitable distance. In particular, the electromechanical
valves permit the generation and dispensing of
adequately large water droplets. A suitably high
positive pressure can be applied in the water supply,
whereby even relatively large spraying distances can
then be covered. The opening times of the valves and
the number of spray pulses are adjustable and can be
adapted to the foil speed. The nozzles are available
with suitable diameters and can be suitably selected in
accordance with the usage situation.
Precise quantity regulation is possible through
adjustment of the droplet size and timing of the
dispensing of the droplets, and by means of the more or
less linear flight path in conjunction with the
synchronization of the web speed. By contrast to the
situation in roller-type application systems of the
prior art, the application quantity, once selected,
remains constant, which leads to constant sealing seam
strengths. Owing to the directed dispensing by means of
outlet nozzles, the liquid passes precisely to its
target location without adjacent regions being
moistened. Spray mist and other disadvantageous
accompanying phenomena are reliably avoided. No
measures are necessary for preventing water damage,
such as holes in the foil, foil tearing, product
contamination, machine damage. An otherwise required
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disposal of excess water-PVA/PVOH mixture, which would
lead to blockages and increased cleaning outlay owing
to hardening and baking-on, is rendered superfluous
according to the invention. In this way, standstill
times that would otherwise arise as a result of a
change of the application roller, cleaning of the water
container or the like are omitted.
The use of an electromechanical spraying system
permits, in particular, a wide variety of adaptations
to the respective situation. For example, one is not
restricted to spraying the respective foil with liquid
over the full area. Rather, the individual outlet
nozzles or solenoid valves may also be individually
controlled and actuated, which permits the dispensing
of the liquid in the form of any desired defined
patterns. For example, it can be achieved that the
moistening is restricted to particular sealing
contours, whereas the other foil sections remain dry.
The foil itself is protected, while at the same time,
sensitive fillings are protected against exposure to
moisture. In the event of a machine being brought to a
standstill and restarted, the spray head can be pivoted
in order to re-moisten particular regions in a targeted
manner. In this way, even after a machine standstill
period, virtually seamless sealing can be realized
without powder or other contents escaping and being
able to contaminate the machine. Bad parts can be
readily separated out, without good parts being
adversely affected along with them.
In an advantageous refinement, the electromechanical
spraying system is mounted so as to be movable, and is
actuable, such that, during operation, it can be
selectively directed toward the cover foil, toward the
base foil or toward a seam line between the cover foil
and the base foil. In this way, it is possible in
particular for start-stop situations during ongoing
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production operation to be allowed for. A situation may
occasionally arise in which the packaging machine must
be stopped proceeding from ongoing filling and sealing
operation. Here, the supply of liquid must also be
interrupted in order that the foil is not excessively
dissolved and torn. Between the pressing line of the
pressing roller and the moistening region acted on by
the spraying system, there is now situated a duly
moistened but unsealed foil section which dries owing
to the standstill situation. After restarting of the
machine, the dried region would, without further
measures, lead to a section with non-sealed or non-
closed packages, which not only constitute waste but
also give rise to contamination of the machine owing to
their filling. The movable mounting and actuation of
the spraying system according to the invention now
permits the execution of a method sequence which
likewise conforms to the invention: after a machine
standstill situation, a restart procedure is performed
in which the mold depressions and the foil webs are
initially not moved onward. However, the cover foil is
folded back or lifted to such an extent that the seam
line between the cover foil and the base foil is
exposed. The spraying system is then directed to the
region of the seam line and moistens the latter.
Proceeding from this, the machine starts in a forward
direction, that is to say transports the mold
depressions and the foil webs in the normal working
direction, wherein then, the previously dried region is
moistened again proceeding from the stated seam line
and is sealed. The containers sealed in the restart
procedure directly adjoin the containers previously
already sealed during normal sealing operation. The
abovementioned restart procedure can finally transition
seamlessly into normal sealing operation without any
sections with open containers remaining. Consequential
problems resulting from escaping filling are reliably
avoided.
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In a preferred embodiment, the sealing apparatus
comprises a doctor blade with a doctor blade edge for
stripping off the excess liquid from the water-soluble
foil web. By means of the doctor blade, any excess
liquid is removed from the cover foil. The liquid
remaining on the cover foil is distributed by means of
the doctor blade such that a uniform liquid film is
formed on the cover foil, which uniform liquid film
improves the homogeneity of the foil sealing.
A gap with a defined gap width is advantageously formed
between the doctor blade edge and the foil web. Through
adjustment of the gap width, the thickness of the
liquid film remaining on the foil web can be exactly
set and also readily adapted as required. Because the
doctor blade edge is not in contact with the foil web,
virtually no mechanical forces arise, which could
otherwise lead to damage to the cover foil.
In an advantageous refinement, the doctor blade
comprises a suctioning apparatus for suctioning the
excess liquid stripped off by the doctor blade edge.
The stripped-off and then suctioned liquid may for
example be conducted into a separate collecting tank or
back into the liquid tank. It is thus possible to
realize adequate removal of the liquid from the cover
foil in particular in the case of high production
speeds and associated high quantities of liquid.
The spraying device is advantageously surrounded by a
housing, a spraying window being formed on the housing
for the targeted application of the liquid to the
water-soluble foil web. By means of the spraying
window, the impingement area of the sprayed liquid can
be more precisely defined. The housing furthermore
prevents undesired moistening, for example, of the
apparatus, of attachment parts and of the surroundings.
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Exemplary embodiments of the invention will be
described below on the basis of the drawings, in which:
figure 1 shows, in a schematic side view, a sealing
apparatus according to the invention for
sealing packages, having a brush roller as
part of a spraying device for moistening a
water-soluble foil web,
figure 2 shows, in an enlarged detail, the sealing
apparatus as per figure 1 with details of a
doctor blade at a pressing roller,
figure 3 shows, in a schematic plan view, the
arrangement as per figure 2 with details
relating to a suctioning mechanism in the
doctor blade,
figure 4 shows, in an enlarged detail view, an
alternative to the sealing apparatus as per
figure 1 with an electromechanical spraying
system directed horizontally toward the upper
cover foil,
figure 5 shows a variant of the arrangement as per
figure 4, in which the electromechanical
spraying system is directed vertically
towards the lower base foil,
figure 6 shows, in a side view, the arrangement as per
figure 4 with the spraying system pivoted
into an operating position during normal
operation, and
figure 7 shows the arrangement as per figure 6 with
the spraying system directed towards the seam
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line between cover foil and base foil during
the execution of a restart procedure.
Figure 1 shows, in a schematic side view, an exemplary
embodiment of a sealing apparatus 1 according to the
invention for sealing packages 26. The individual
packages 26 comprise a base foil 22, which is sealed
with a cover foil 5. The base foil 22 and the cover
foil 5 are each formed from a water-soluble foil web
23, which in turn is preferably composed of PVOH
(polyvinyl alcohol). Other water-soluble materials may
however also be expedient for the foil web 23. A single
foil web 23 may be provided which is folded over to
form the base foil 22 and the cover foil 5. In the
preferred exemplary embodiment shown, in each case one
separate foil web 23 is provided for the base foil 22
and for the cover foil 5. The base foil 22 is
expediently deep-drawn into the form of depressions
prior to the sealing process, wherein the depressions
of the cover foil 5 are filled with a filling (not
illustrated in any more detail), for example a powder
or a liquid medium. An embodiment without plastic
deformation and depression formation, for example in
the form of a sealed tubular bag package, may however
also be expedient. Furthermore, in the context of the
invention, embodiments are also conceivable in which
only the cover foil or only the base foil is formed
from a water-soluble foil web 23.
The sealing apparatus 1 is designed for moisture-based
sealing of the cover foil 5 onto the base foil 22. For
this purpose, said sealing apparatus comprises a liquid
supply for a water-containing liquid 3, at least one
moistening unit for wetting the water-soluble foil web
23 with the liquid 3, and a pressing device 24 for
pressing and sealing the cover foil 5 together with the
base foil 22 in the state in which they are wetted with
the liquid 3. With the moistening unit shown here, the
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foil web 23 of the cover foil 5 is moistened.
Alternatively or in addition, it is however also
possible for the foil web 23 of the base foil 22 to be
analogously expediently moistened or wetted.
According to the invention, the moistening unit is
formed as a spraying device 4 for contactlessly
spraying the liquid 3 onto the water-soluble foil web
23, and is positioned at a distance a from the water-
soluble foil web 23. The spraying device 4 may be
formed by one or more spraying nozzles which are
directed toward the water-soluble foil web 23 and by
means of which the water-containing liquid 3 is sprayed
onto the foil web 23. In the preferred exemplary
embodiment shown as per figure 1, the spraying device
comprises a brush roller 9 and optionally a stripper 15
described in more detail further below. The brush
roller 9 comprises a cylindrical roller body 10, to the
circumferential side of which there are fastened
radially projecting bristles 11.
The spraying device 4 is fed with the water-containing
liquid 3 by means of the liquid supply already
mentioned in the introduction and described in more
detail further below. For this purpose, the brush
roller 9 is moistened by the liquid supply during
operation. In the exemplary embodiment as per figure 1,
the liquid supply is realized as a liquid tank 2 with
the water-containing liquid 3 situated therein, wherein
the liquid forms a liquid surface 13. The brush roller
9 is positioned relative to the liquid tank 2 such that
the bristles 11 extend below the liquid surface 13 and
consequently dip into the liquid 3 situated in the
liquid tank 2. By control means which are not shown, it
is achieved that, during operation, the height of the
liquid surface 13 and thus the depth to which the
bristles 11 dip into the liquid 3 remains substantially
constant. Alternatively or in addition to the liquid
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tank 2, it is however for example also possible for a
water line to be provided, from which the brush roller
9 is directly moistened. The water-containing liquid 3
may simply be mains water, water with added tensides or
the like. In any case, its water content must be high
enough that it dissolves the surface of the water-
soluble foil web 23 upon contact.
Owing to the rotational movement of the brush roller 9,
the liquid 3 absorbed by the bristles 11 is
centrifuged. The quantity of liquid centrifuged by the
brush roller 9 may be set for example through
adaptation of the depth to which the bristles 11 dip
into the liquid 3, that is to say through height
adjustment of the brush roller 9 and/or through height
adjustment of the liquid surface 13 and through
selection of a suitable rotational speed of the brush
roller 9. The foil web 23 to be moistened, in this case
for example the foil web 23 from which the cover foil 5
is formed, is led past the brush roller 9 at a distance
a such that the centrifuged liquid 3 is sprayed against
the cover foil 5. The cover foil 5 that has been
moistened with the liquid 3 and consequently dissolved
at its surface is brought together with the base foil,
and pressed together with the latter, at the pressing
device 24, wherein the dissolved foil surface gives
rise, in conjunction with the exerted pressing
pressure, to sealing of the cover foil 5 together with
the base foil 22. In the exemplary embodiment of figure
1, to generate the pressing pressure, the pressing
device 24 is designed as a pressing roller 6 which
rotates about an axis of rotation 12 and by means of
which the cover foil 5 is sealed under pressure onto
the base foil running therebelow. The pressing device
24 may however for example also comprise two pressing
plates which press against one another. Furthermore,
said pressing device may optionally also comprise an
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additional heating station, such that combined
moisture-based sealing and hot sealing is performed.
The optional stripper 15 already mentioned above is
arranged on that side of the brush roller 9 which
points toward the foil web 23 to be moistened, such
that said stripper projects with its stripping edge 16
between the bristles 11, that is to say into the
imaginary envelope cylinder of the bristles 11. As the
brush roller 9 rotates, the bristles 11 make contact
with the stripping edge 16 of the stripper 15 and are
bent back against the stripping edge 16 counter to the
direction of rotation of the brush roller 9. During
further rotation, the bent-back bristles 11 slide past
the stripping edge 16, straighten under the action of
centrifugal force and resilient restoring force, and
spray the absorbed liquid 3 in the direction of the
cover foil 5. The resilient spring-back of the bristles
11 assists the centrifugal action, which is present in
any case, during the centrifuging of the liquid 3, and
furthermore imparts a defined spraying direction to the
centrifuged liquid. Through selection or setting of a
suitable relative position of the stripper 15 relative
to the brush roller 9, it is possible to set not only
the liquid quantity to be dispensed but in particular
also the spraying direction of the liquid 3 and thus
the region in which it impinges on the foil web 23.
In figure 1, it can also be seen that the spraying
device 4 is surrounded by a housing 7, which serves
inter alia as a spray guard with respect to the
surroundings. In the housing 7 there is formed a
spraying window 8 which is positioned between the
spraying device 4 and the foil web 23 such that
directed spraying of the liquid 4 onto a particular
target area of the foil web 23 by means of the brush
roller 9 is assisted. Optionally, a means may be
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provided for adjusting the size and relative position
of the spraying window 8.
In the preferred embodiment shown, the sealing
apparatus also has a doctor blade 17 with a doctor
blade edge 18, wherein the doctor blade edge 18 is
positioned directly adjacent to the foil web 23. In
relation to the direction in which the foil web 23
passes through, the doctor blade edge 18 is positioned
downstream of the impingement zone of the sprayed-on
liquid 3, and is arranged here such that the doctor
blade edge 18 strips off the excess liquid 3 from the
foil web 23. Through suitable design and positioning of
the doctor blade 17 and of its doctor blade edge 18,
possibly assisted by drainage and/or suctioning means
described in more detail further below, the liquid 3
stripped off from the cover foil 5 is collected and can
be conducted for example into a separate collecting
tank or back into the liquid tank 2.
Figure 2 shows, in an enlarged detail view, the sealing
apparatus as per figure 1 in the region of the doctor
blade 17 and of the pressing roller 6. In the preferred
exemplary embodiment shown, the doctor blade 17 is
positioned such that the doctor blade edge 18 is
positioned adjacent to the foil web 23 where the foil
web 23 loops around the pressing roller 6, preferably
at the start of the looped-around portion. Although the
doctor blade edge 18 directly adjoins the foil web 23,
it is however not in physical contact with the foil web
23. Rather, a gap with a defined gap width b remains
between the doctor blade edge 18 and the facing surface
of the foil web 23. Owing to the gap width b, it is
firstly the case that excess liquid 3 is stripped off
from the surface of the foil web 23 in a contactless
manner, that is to say without mechanical load on the
foil web 23, while secondly, a liquid film whose
thickness is predefined by the gap width b remains on
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the surface of the foil web 23. Thus, the quantity of
liquid 3 on the surface of the foil web 23, and the
dissolving action thereof, are precisely predefined.
The gap width b may be adjustable in particular by
suitable means (not shown here) for positioning the
doctor blade edge 18 relative to the circumferential
surface of the pressing roller 6.
Figure 3 shows, in a schematic plan view, the
arrangement as per figure 2 with the doctor blade 17
and the pressing roller 6. Viewing figures 2 and 3
together, it can be seen that, in the doctor blade 17,
there is arranged a collecting channel 25 in which
stripped-off liquid 3 is collected. In the base of the
collecting channel there are situated drainage openings
14. The collected liquid 3 can drain passively through
the drainage openings 14. In the preferred exemplary
embodiment shown, the collecting channel 25 and the
drainage openings 14 are part of a suctioning apparatus
19, by means of which the collected liquid 3 is
actively suctioned and conducted away from the doctor
blade 17.
Figure 4 shows, in a perspective detail view, an
alternative to the sealing apparatus 1 as per figures 1
to 3. Instead of the above-described brush roller 9,
the spraying device 4 in this case comprises an
electromechanical spraying system 30. The
electromechanical spraying system 30 has a row of
outlet nozzles 31, wherein said row extends
transversely over the cover foil 5 and, for the sake of
simplicity, is shown here merely as a block
illustration. The outlet nozzles 31 are directed toward
that surface of the cover foil 5 which later faces
toward the base foil 22, specifically where the cover
foil 5 loops around the pressing roller 6. During
operation, the water-containing liquid 3 is sprayed
contactlessly onto the cover foil 5 by means of the
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electromechanical spraying system 30 and its row of
outlet nozzles 31, for which purpose each individual
outlet nozzle 31 forms in each case one droplet jet 33.
The droplet jets 33 impinge on the cover foil 5 with a
sufficiently close spacing, such that a closed film of
the liquid 3 forms there. It is however alternatively
also possible for a particular moistening pattern to be
achieved through targeted control or actuation of the
individual outlet nozzles 31. In any case, the cover
foil 5 moistened in this way, and thus dissolved at its
surface, is rolled under pressure onto planar sealing
sections 27 of the base foil 22 by means of the
pressing roller 6. Since very precisely dimensioned
liquid quantities can be applied, intimate sealing
between the cover foil 5 and the base foil 22 is
realized at the sealing sections 27 already after a
very short action and drying time, whereby sealingly
closed packages 26 are formed. Although not
imperatively necessary according to the invention, the
pressing roller 6 may additionally also be heated in
order to accelerate the sealing process.
In the schematic block illustration as per figure 4,
each individual outlet nozzle 31 is assigned in each
case one solenoid valve 32, such that in each case one
outlet nozzle 31 and in each case one associated
solenoid valve 32 are thus provided for forming all of
the droplet jets 33. Instead of the solenoid valves 32,
it is however also possible to use bubble-jet units or
piezo units such as are known from inkjet printer
technology. The solenoid valves 32 are individually
controllable or actuable by means of a suitable control
unit (not shown in any more detail here), whereby areal
foil moistening, or else any desired moistening
patterns, are possible. Such a moistening pattern could
for example correspond to the pattern of the sealing
sections 27. It is then the case that a dissolved foil
surface for sealing purposes is actually provided only
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where the cover foil 5 meets the base foil 27, whereas
the cover foil 5 remains dry where it covers the
product filling that has been introduced into the deep-
drawn cavities. Through suitable control, a
synchronization of the application of liquid with the
feed speed of the cover foil 5 and/or of the base foil
22 is also possible.
The illustration of figure 4 shows only a unit or a
single print head as an electromechanical spraying
system 30, wherein the outlet nozzles 31, or the
droplet jets 33 generated by these, are oriented for
example horizontally. To cover relatively large foil
widths, that is to say if the foil width is greater
than the working width of a single print head,
overlapping nesting of multiple such print heads may
also be expedient. These are preferably oriented
parallel to one another in terms of their jet
direction, such that the droplet jets 33 impinge in a
manner offset with respect to one another in blockwise
fashion, analogously to the overlapping nesting of the
print heads. If the mutual offset is small enough,
adequately uniform moistening is nevertheless realized.
The print heads may however also be pivoted relative to
one another in terms of their jet direction, such that
the droplet jets 33 impinge along a common line. In any
case, in this way, uniform wetting with liquid is
possible even in the case of a very large foil width.
Through active, controlled pivoting of the
electromechanical spraying system 30, for example about
a horizontal pivot axis 42, it is also possible for the
impingement location of the droplet jets 33 to be
varied or adapted, whereby, for example following a
machine standstill period, targeted re-wetting of the
foils, and thus gapless sealing, are possible. Details
in this regard will be discussed further below in
conjunction with figures 6 and 7.
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A variant of the arrangement and of the method as per
figure 4 is shown in figure 5. Here, the
electromechanical spraying system 30 is oriented such
that the droplet jets 33 impinge not on the cover foil
5 but on the base foil 22. The outlet nozzles 31
(figure 4) are, for this purpose, directed vertically
downward. An oblique-angled orientation may however
also be expedient. In figure 5, it is provided that
control of the outlet nozzles 31 or of the solenoid
valves 32 (figure 4), and synchronization with the feed
movement of the base foil 22, are provided such that
only the planar upper sealing sections 27 are wetted
with liquid 3 (figure 4). The interposed cavities
filled with product material are not sprayed with
moisture. In particular in the case of filling
materials with low sensitivity to moisture, it may
however also be expedient for the lower base foil 22 to
be sprayed with liquid over the full area, wherein it
is then tolerated that the product filling, which is
exposed at this point in time, is impinged on with a
small quantity of liquid. In terms of the other
features and reference designations, the exemplary
embodiments as per figures 4 and 5 correspond to one
another and to the exemplary embodiment as per
figures 1 to 3.
Figure 6 shows, in a side view, the arrangement as per
figure 4 with further details during normal operation.
As already mentioned in conjunction with figure 4, the
electromechanical spraying system 30 is mounted so as
to be movable, specifically pivotable about a
horizontal pivot axis 42. Through suitable control, it
is possible during operation for pivoting of the
spraying system 30, and thus a change or adaptation of
the direction of the droplet jets 33, to be performed.
The pressing device 24 is also pivotably mounted,
specifically about a pivot axis 41. Aside from the
pressing roller 6 already illustrated in figure 4, the
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pressing device 24 also has an optional diverting
roller 43. During normal operation, as shown, the cover
foil is tensioned between the diverting roller 43 and
the pressing roller 6 so as to form an approximately
vertical surface, while the electromechanical spraying
system 30 is directed with its droplet jets 33 toward
said vertical surface. The cover foil 5 moistened in
this way is transported onward in the direction of an
arrow 44 to the pressing roller 6, and is diverted
there into a horizontal direction. Lower deep-drawing
molds, together with the base foil 22 deep-drawn into
said molds, are likewise arranged in a horizontal
direction. The functional unit now formed from the
lower deep-drawing molds, the cover foil 5 and the base
foil 22 is transported onward in a normal working
direction corresponding to an arrow 40, wherein the
moistened cover foil 5 is sealed onto the base foil 22
along a horizontally running pressing line 35 so as to
form closed packages.
If the ongoing normal sealing operation is now
interrupted, the onward transport of the cover foil 5
in the direction of the arrow 44, and the feed movement
of the molds with the base foil 22 deep-drawn into them
in the direction of the arrow 40, are stopped. Owing to
the standstill situation, a seam line 37 forms at the
pressing line 35, on the entry side of which no further
sealing occurs. Furthermore, the liquid supply by means
of the spraying system 30 is interrupted. The droplet
jets 33 are stopped. Between the impingement line 36
and the seam line 37, there is situated a duly
moistened but unsealed section of the cover foil 5,
which dries after a short standstill time. In the case
of a resumption of normal operation without further
measures, the resumed liquid supply would effect
moistening of the cover foil proceeding from the
impingement line 36 and on the entry side thereof,
while the foil section between the impingement line 36
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and the seam line 37 remains dry. Prepared packages
corresponding to this section that has remained dry
would not be sealed, such that the content with which
they have already been filled can escape.
In one advantageous aspect of the invention, it is
however the case that the electromechanical spraying
system 30 is movably mounted, and controllable, such
that, during operation, it can be selectively directed
toward the cover foil 5 or toward a seam line 37
between the cover foil 5 and the base foil 22, wherein
positions in between can also be assumed. In a method
sequence according to the invention, it is now the
case, after the machine standstill period as discussed
above, that a restart procedure is executed. Proceeding
from the normal operating position as per figure 6, the
pressing device 24 is, for this purpose, pivoted upward
corresponding to an arrow 38, and in the process is
lifted from the stack of cover foil 5 and base foil 22.
Here, the still-unsealed part of the cover foil 5 is
pulled upward, and held taut, to such an extent that
the seam line 37 is no longer covered by the cover foil
5, but rather passes into the region of action of the
spraying system 30. Proceeding from the normal
operating position as per figure 6, the
electromechanical spraying system 30 is now pivoted so
as to be directed toward the exposed seam line 37. The
spraying system 30 is now set in operation again, such
that its droplet jets 33 impinge on the region of the
seam line 37. Proceeding from here, the entire
previously dried region between seam line 37 and old
impingement line 36 as per figure 6 is re-moistened.
This is preferably performed by means of controlled
pivoting of the spraying system 30, with continuously
emerging droplet jets 33, back into the operating
position as per figure 6, wherein then, the
corresponding section of the cover foil 5 is moistened.
Alternatively or in addition to this, it is also
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possible for a corresponding section on the base foil
22 to be moistened and thus prepared for sealing. It is
preferably the case that, in parallel with the re-
moistening of the previously dried foil region or else
possibly following this, the pressing device 24 is
moved back into its normal operating position as per
figure 6. As soon as the normal operating position has
been reached, the functional unit already mentioned
above composed of the lower deep-drawing molds, the
cover foil 5 and the base foil 22 is set in motion
again and is transported onward in the normal working
direction corresponding to the arrow 40, wherein the
re-moistened region of the cover foil 5 is sealed onto
the base foil 22. This then subsequently transitions in
uninterrupted fashion into normal sealing operation as
per figures 4 and 6 or as per figure 5, with the
restart procedure being ended, as soon as the re-
moistened region of the cover foil 5 has fully passed
the pressing line 35 and as soon as fresh cover foil 5,
or cover foil 5 that has been moistened for the first
time, arrives at this location.
The quality of the seals produced in this way during
the restart procedure can suffice for the corresponding
packages to meet the specifications, and to not
constitute waste. Even if visual and/or technical
losses in quality occur here, an at least temporarily
functioning seal is nevertheless produced, as a result
of which no contents can escape from the affected
packages and contaminate the machine.
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