US20180134431A1

US20180134431A1 - Sealing apparatus and method for sealing packaging

Info

Publication number: US20180134431A1
Application number: US15/816,621
Authority: US
Inventors: Andreas Thienst; Achim Wolf; Fritz Major; Udo Egelkraut; Uwe Blum
Original assignee: Harro Hofliger Verpackungsmaschinen GmbH
Current assignee: Harro Hofliger Verpackungsmaschinen GmbH
Priority date: 2016-11-17
Filing date: 2017-11-17
Publication date: 2018-05-17
Also published as: ES2769910T3; EP3323740B1; EP3323740A1; CA2985762A1; CN108069060A; PL3323740T3

Abstract

A packaging includes a base foil and a cover foil, the base foil and/or the cover foil being formed from a water-soluble foil web. The apparatus includes a liquid supply for a water-containing liquid, at least one moistening unit, and a pressing device. The moistening unit is formed as a spraying device for contactlessly spraying the liquid onto the foil web and is positioned at a distance (a) from the foil web. The spraying device includes an electromechanical spraying system with a row of outlet nozzles for spraying the liquid onto the foil web. The water-soluble foil web is supplied to the sealing apparatus. A water-containing liquid is sprayed onto the foil web via the spraying device. The cover foil is led onto the base foil and is pressed and sealed together therewith, in the state in which they are wetted with the liquid, via a pressing device.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of European patent application no. 16 400 052.3, filed Nov. 17, 2016, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

Disclosed is a sealing apparatus for sealing packaging and to a method for sealing packaging with an apparatus of this type.

BACKGROUND OF THE INVENTION

Washing or dishwashing agents for household use are increasingly packaged in the form of powders or liquids in water-soluble packaging. The packages are made 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 packaging, 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. The depressions are filled with the filling. A cover foil is subsequently sealed onto the base foil. Via 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 the 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 via a moistening unit, for example with a felt roller. The moistened felt roller rolls on the water-soluble foil web, whereby the surface of the foil web is dissolved. The cover foil with dissolved surface is then pressed via 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 via 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 one 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 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.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a sealing apparatus such that an improved application of liquid to the water-soluble foil web is achieved.
The object can, for example, be achieved via a sealing apparatus for sealing packaging, wherein the packaging includes a base foil and a cover foil, at least one of the base foil and the cover foil being made of a water-soluble foil web. The sealing apparatus includes: a liquid supply for a water-containing liquid; a moistening unit configured to moisten the water-soluble foil web with the water-containing liquid; a pressing device configured to press together and seal the cover foil and the base foil with the foil web being moistened; the moistening unit being formed as a spraying device configured to spray the water-containing liquid onto the water-soluble foil web in a contact-free manner; the spraying device being configured to be positioned at a distance (a) to the water-soluble foil web; and, the spraying device being an electromechanical spray system having a row of outlet nozzles configured to spray the water-containing liquid onto the water-soluble foil web.
It is a further object of the invention to provide a method for sealing packages, via which method moistening of the water-soluble foil web can be performed in a more effectively metered manner.
The object can, for example, be achieved via a method for sealing packaging via a sealing apparatus wherein the packaging includes a base foil and a cover foil, at least one of the base foil and the cover foil being made of a water-soluble foil web, the sealing apparatus including a liquid supply for a water-containing liquid, a moistening unit configured to moisten the water-soluble foil web with the water-containing liquid, a pressing device configured to press together and seal the cover foil and the base foil with the foil web being moistened, the moistening unit being formed as a spraying device configured to spray the water-containing liquid onto the water-soluble foil web in a contact-free manner, and, the spraying device being an electromechanical spray system having a row of outlet nozzles configured to spray the water-containing liquid onto the water-soluble foil web. The method includes the steps of: feeding the water-soluble foil web to the sealing apparatus; positioning the spraying device at a distance (a) to the water-soluble foil web; spraying the water-containing liquid onto the water-soluble foil web via the spraying device; guiding the cover foil onto the base foil; and, pressing and sealing the cover foil to the base foil via the pressing device with the foil web in a wetted state.
According to an aspect of 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 an 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, via 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 the base foil, in the state in which they are wetted with the liquid, via a pressing device.
An underlying concept on which the invention is based on that 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, via 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 embodiments 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.
According to an aspect of the invention, the spraying device includes 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, via 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 via 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 via 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 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 an aspect of 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 embodiment, 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 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 an aspect of the invention now permits the execution of a method sequence: 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, 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.
In a preferred embodiment, the sealing apparatus includes a doctor blade with a doctor blade edge for stripping off the excess liquid from the water-soluble foil web. Via the doctor blade, any excess liquid is removed from the cover foil. The liquid remaining on the cover foil is distributed via 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 embodiment, the doctor blade includes 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. Via 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.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawings wherein:

FIG. 1 shows, in a schematic side view, a sealing apparatus according to the invention for sealing packaging, having a brush roller as part of a spraying device for moistening a water-soluble foil web;

FIG. 2 shows, in an enlarged detail, the sealing apparatus as per FIG. 1 with details of a doctor blade at a pressing roller;

FIG. 3 shows, in a schematic plan view, the arrangement as per FIG. 2 with details relating to a suctioning mechanism in the doctor blade;

FIG. 4 shows, in an enlarged detail view, an alternative to the sealing apparatus as per FIG. 1 with an electromechanical spraying system directed horizontally toward the upper cover foil;

FIG. 5 shows a variant of the arrangement as per FIG. 4, in which the electromechanical spraying system is directed vertically towards the lower base foil;

FIG. 6 shows, in a side view, the arrangement as per FIG. 4 with the spraying system pivoted into an operating position during normal operation; and,

FIG. 7 shows the arrangement as per FIG. 6 with the spraying system directed towards the seam line between cover foil and base foil during the execution of a restart procedure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows, in a schematic side view, an embodiment of a sealing apparatus 1 according to the invention for sealing packaging 26. The individual packages 26 include 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 made 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 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 configured for moisture-based sealing of the cover foil 5 onto the base foil 22. For this purpose, the sealing apparatus includes 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 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 an aspect of 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 via which the water-containing liquid 3 is sprayed onto the foil web 23. In the preferred embodiment shown as per FIG. 1, the spraying device includes a brush roller 9 and optionally a stripper 15 described in more detail further below. The brush roller 9 includes 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 via 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 embodiment as per FIG. 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 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, 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 embodiment of FIG. 1, to generate the pressing pressure, the pressing device 24 is configured as a pressing roller 6 which rotates about an axis of rotation 12 and via which the cover foil 5 is sealed under pressure onto the base foil running therebelow. The pressing device 24 may, however, for example, also include two pressing plates which press against one another. Furthermore, the pressing device may optionally also include an 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 the stripper projects with its stripping edge 16 between the bristles 11, that is, 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 FIG. 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 via the brush roller 9 is assisted. Optionally, a means may be 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 configuration 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.
FIG. 2 shows, in an enlarged detail view, the sealing apparatus as per FIG. 1 in the region of the doctor blade 17 and of the pressing roller 6. In the preferred 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, without mechanical load on the foil web 23, while secondly, a liquid film whose thickness is predefined by the gap width b remains on 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.
FIG. 3 shows, in a schematic plan view, the arrangement as per FIG. 2 with the doctor blade 17 and the pressing roller 6. Viewing FIGS. 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 embodiment shown, the collecting channel 25 and the drainage openings 14 are part of a suctioning apparatus 19, via which the collected liquid 3 is actively suctioned and conducted away from the doctor blade 17.
FIG. 4 shows, in a perspective detail view, an alternative to the sealing apparatus 1 as per FIGS. 1 to 3. Instead of the above-described brush roller 9, the spraying device 4 in this case includes an electromechanical spraying system 30. The electromechanical spraying system 30 has a row of outlet nozzles 31, wherein the 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 via the 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 via 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 an aspect of 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 FIG. 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 via 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 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 FIG. 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, 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 FIGS. 6 and 7.
A variant of the arrangement and of the method as per FIG. 4 is shown in FIG. 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 (FIG. 4) are, for this purpose, directed vertically downward. An oblique-angled orientation may however also be expedient. In FIG. 5, it is provided that control of the outlet nozzles 31 or of the solenoid valves 32 (FIG. 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 (FIG. 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 embodiments as per FIGS. 4 and 5 correspond to one another and to the embodiment as per FIGS. 1 to 3.
FIG. 6 shows, in a side view, the arrangement as per FIG. 4 with further details during normal operation. As already mentioned in conjunction with FIG. 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 FIG. 4, the 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 the 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 the 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 via 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 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 an aspect of 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 FIG. 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 FIG. 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 FIG. 6 is re-moistened. This is preferably performed via controlled pivoting of the spraying system 30, with continuously emerging droplet jets 33, back into the operating position as per FIG. 6, wherein then, the corresponding section of the cover foil 5 is moistened. Alternatively or in addition to this, it is also 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 FIG. 6. As soon as the normal operating position has been reached, the functional unit already mentioned above made 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 FIGS. 4 and 6 or as per FIG. 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.
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

What is claimed is:

1. A sealing apparatus for sealing packaging, wherein the packaging includes a base foil and a cover foil, at least one of said base foil and said cover foil being made of a water-soluble foil web, the sealing apparatus comprising:

a liquid supply for a water-containing liquid;

a moistening unit configured to moisten the water-soluble foil web with the water-containing liquid;

a pressing device configured to press together and seal the cover foil and the base foil with the foil web being moistened;

said moistening unit being formed as a spraying device configured to spray the water-containing liquid onto the water-soluble foil web in a contact-free manner;

said spraying device being configured to be positioned at a distance a to the water-soluble foil web; and,

said spraying device being an electromechanical spray system having a row of outlet nozzles configured to spray the water-containing liquid onto the water-soluble foil web.

2. The sealing apparatus of claim 1, wherein said electromechanical spray system includes a row of solenoid valves associated with said outlet nozzles.

3. The sealing apparatus of claim 1, wherein said electromechanical spray system is movably mounted and controllable such that during operation said electromechanical spray system is configured to be directed toward said cover foil or a seam line between said cover foil and said base foil.

4. The sealing apparatus of claim 1 further comprising a doctor blade having a doctor blade edge configured to remove excess liquid from the water-soluble foil web.

5. The sealing apparatus of claim 4, wherein said doctor blade edge and the water-soluble foil web are configured to define a mutual gap having a defined gap width B.

6. The sealing apparatus of claim 4, wherein said doctor blade includes a suctioning device configured to suction off excess liquid removed by said doctor blade edge.

7. The sealing apparatus of claim 1 further comprising:

a housing;

said spraying device being enclosed by said housing; and,

said housing defining a spray window for directed application of the liquid onto the water-soluble foil web.

8. A method for sealing packaging via a sealing apparatus wherein the packaging includes a base foil and a cover foil, at least one of the base foil and the cover foil being made of a water-soluble foil web, the sealing apparatus including a liquid supply for a water-containing liquid, a moistening unit configured to moisten the water-soluble foil web with the water-containing liquid, a pressing device configured to press together and seal the cover foil and the base foil with the foil web being moistened, the moistening unit being formed as a spraying device configured to spray the water-containing liquid onto the water-soluble foil web in a contact-free manner, and, the spraying device being an electromechanical spray system having a row of outlet nozzles configured to spray the water-containing liquid onto the water-soluble foil web, the method comprising the steps of:

feeding the water-soluble foil web to the sealing apparatus;

positioning the spraying device at a distance a to the water-soluble foil web;

spraying the water-containing liquid onto the water-soluble foil web via the spraying device;

guiding the cover foil onto the base foil; and,

pressing and sealing the cover foil to the base foil via the pressing device with the foil web in a wetted state.