Sealing tool for a skin packaging

Abstract

The invention relates to an upper tool for a sealing station of a packaging machine, having a recess with which an upper film web can be formed and having a plurality of gas through-openings, which are provided along the recess and can be connected to an overpressure, underpressure and / or ventilation source. The invention also relates to a packaging machine and to a method for producing a skin packaging.

Description

[0001] Sealing tool for a skin packaging

[0002] The present invention relates to an upper tool for a sealing station of a packaging machine, which tool has an indentation with which an upper film web can be formed and a plurality of gas passages provided along the indentation and connectable to a source of negative pressure, positive pressure, and / or ventilation. Furthermore, the present invention relates to a packaging machine and a method for producing a skin-like package.

[0003] In skin packaging, the top film web lies directly against the packaged product, at least partially following its contour, and is extensively bonded to the packaging tray on which the packaged product is located. However, the product often adheres insufficiently to the packaging products.

[0004] It was therefore the object of the present invention to provide an upper tool with which the disadvantages of the prior art can be overcome.

[0005] The object is achieved with an upper tool for a sealing station of a packaging machine, which has an indentation with which an upper film web can be formed and with a plurality of gas passages which are provided along the indentation and can be connected to a negative pressure, positive pressure and / or ventilation source, wherein gas passages can be divided into at least two groups which can be connected independently of one another to the negative pressure, positive pressure and / or ventilation source.

[0006] The statements made regarding this subject matter apply equally to the other subject matters of the present invention, and vice versa. Features disclosed in connection with this subject matter of the present invention can be combined with other subject matters, and vice versa.

[0007] The present invention relates to an upper tool having at least one indentation into which an upper film is sucked and formed in the process. With the upper film formed in an indentation, one, two, three, four or more packaging trays can be closed, in particular gas-tight. With a preferably present surrounding housing / clamping tool, the upper film is preferably fixed during deformation and / or the surrounding housing / clamping tool preferably seals the space between the indentation and the upper film. The upper tool according to the invention is preferably heated. During deformation, the originally flat film web adheres to the contour of the indentation and is heated in the process, in particular by heat conduction.

[0008] According to the invention, the upper tool has a plurality of gas passages, in particular bores, particularly in the region of the indentation and / or is made of a porous material so that it is gas-permeable. These gas passages can be connected to a negative pressure, positive pressure, and / or ventilation source. The negative pressure source can be used to create a negative pressure between the indentation and the upper film, which draws the upper film into the indentation and thereby shapes it. The positive pressure and / or ventilation source can be used to reduce the negative pressure towards ambient pressure and / or to push the upper film web towards the packaged goods. However, preferably, only a ventilation source and no positive pressure source is provided.

[0009] Furthermore, according to the invention, the gas passages can be divided into at least two groups, which can be connected independently of one another to the negative pressure, positive pressure, and / or ventilation source. Preferably, the two groups are divided into regions: a central region and an edge region surrounding this central region, in particular in a ring shape. For example, the negative pressure with which the upper film web was sucked onto the depression can be maintained in the edge region, while in the central region the gas passages are already connected to a ventilation source in order to, in particular partially, reduce the negative pressure. As a result, the upper film web detaches in the central region and assumes a shape different from that of the indentation, while it continues to adhere to the edge region.

[0010] The central region can, for example, have a round, oval, square, or rectangular circumference. The edge region is preferably annular, with the shape of the ring preferably being adapted to the shape of the central region. The central region is preferably the geometric center of the indentation. The edge region preferably encloses the central region in a ring.

[0011] Preferably, one or more packages can be produced with one upper tool.

[0012] The upper tool according to the invention ensures that the upper film adheres completely to the packaged goods. The upper tool preferably has chambers, preferably upstream of the gas flow during venting. Each chamber defines the gas passages of a group. Each chamber preferably has a circumferential wall and a base and a lid region. The gas passages of the respective group are provided in the base region. The base region is preferably the wall of the recess. The lid region is preferably sealed gas-tight and / or has a connection to the respective negative pressure, positive pressure, and / or ventilation source for the respective group.

[0013] Preferably, pressure, in particular negative pressure, and / or ventilation in the chamber is controlled by a valve. The valve can preferably be used to control the gas volume flow. Preferably, the valve can be used to switch between the sources, in particular between the negative pressure and the ventilation source. At least the chamber in the central region, but preferably also the chamber in the peripheral region, has a valve that is in particular individually controllable and is connected to the negative pressure, positive pressure, and / or ventilation source, in particular to the ventilation source on the gas side.

[0014] Preferably, a group and / or a chamber is provided in a central region, in particular the recess. The central region is preferably the geometric center of the recess.

[0015] According to a preferred embodiment of the present invention, a further chamber, particularly annular, extends around the chamber in the central region. "Annular" within the meaning of the invention does not necessarily mean circular. The ring can have any shape familiar to those skilled in the art, with a square or rectangular annular chamber being preferred.

[0016] The upper tool preferably has a pressure sensor, particularly in the central area. The pressure sensor measures the pressure between the indentation and the upper film. The pressure sensor signal is used, in particular, to initiate ventilation of the ring area.

[0017] Preferably, a negative pressure, the product vacuum, is created in the product area, i.e., between the bottom material web and the top film, particularly during the forming of the top film and / or during the venting of the volume between the indentation and the top film, preferably by connecting this volume to a vacuum source. Preferably, the product vacuum is not maintained during the venting of the volume between the indentation and the top film. Preferably, a negative pressure, the so-called sub-vacuum, is also created below the packaging trough, particularly to prevent the packaging trough from deforming due to the product vacuum.

[0018] Preferably, an unheated, flat upper film is formed in the upper tool according to the invention. The upper film lies flat against the indentation of the upper tool and is thus heated evenly. Because the upper film is preferably not preheated or prestretched, the energy requirement for producing a skin-like packaging is comparatively low. A conventional packaging machine can be easily converted into a "skin-like packaging machine" using the upper tool according to the invention by replacing the conventional upper tool with the upper tool according to the invention.

[0019] The conversion is preferably made possible by a modular design of the upper tools and is preferably carried out in the sense of a quick tool change, for example using a tool structure as described in WO 2013127963 A1 by the present applicant, in which the upper tool remains on the packaging machine and only the tool insert therein, i.e. the upper tool, is changed. The upper tool according to the invention can therefore be retrofitted to existing packaging machines. The person skilled in the art understands that the upper tool in this case can be a tool for skin packaging or a conventional tool, for example for so-called "modified atmosphere packaging" (MAP) or vacuum packs or simple packs without a modified atmosphere, and allows the user of the packaging machine to package different products with different applications.Each of these tools can be easily integrated into the packaging machine, making it versatile.

[0020] A further inventive or preferred subject matter of the present invention is a packaging machine in which a packaging tray is filled with a packaged product in a filling station and which has a sealing station in which the packaged product is enclosed with an upper film in an at least substantially form-fitting manner and the upper film is connected to the packaging tray, wherein the sealing station has an upper tool according to one of the preceding claims.

[0021] The statements made regarding this subject matter apply equally to the other subject matters of the present invention, and vice versa. Features disclosed in connection with this subject matter of the present invention can be combined with other subject matters, and vice versa.

[0022] The subject matter of the present invention relates to a packaging machine in which a packaging tray is provided. This can be done by forming the packaging tray into a flat material web or by providing a prefabricated packaging tray. However, the packaging tray within the meaning of the invention does not have to be deep-drawn at all. The material web can be a film, cardboard or another material. The packaging machine according to the invention can, for example, be a so-called thermoformer or also a so-called tray sealer. In a next step, this packaging tray is filled with a packaged item, in particular a foodstuff, preferably a protein-containing foodstuff. The packaged item can protrude beyond the upper edge of the packaging tray.According to the invention, the packaging machine has a sealing station in which the packaged goods are at least substantially positively enclosed by a top film. Packaging in which the packaged goods are provided in a comparatively rigid packaging tray and in which the packaged goods are substantially positively enclosed by a top film is referred to by those skilled in the art as so-called skin packaging. The top film preferably bonds over a large area, particularly preferably over a very large area, to the packaging tray, in particular to the entire surface of the packaging tray facing the top film that is not covered by the packaged goods.

[0023] The packaging machine preferably operates in cycles, with a plurality of packages preferably being produced simultaneously in one cycle.

[0024] The sealing station has the upper tool according to the invention. Furthermore, the packaging machine according to the invention has a control system with which it is possible to subject the individual groups of gas outlets to different pressures, in particular negative pressures, independently of one another and / or to ventilate the individual groups differently, i.e. to reduce the negative pressure differently. For this purpose, the packaging machine according to the invention has, for example, valve(s) that can be controlled individually and which connect the respective group, for example, to a negative pressure source and / or a ventilation source. Particularly preferably, the valve not only enables on / off control, but can also control the volume flow of gas from and / or to the respective group of gas outlets. The evacuation of the space between the indentation and the upper film web preferably takes place with all gas outlets simultaneously.

[0025] The upper tool can have a sealing frame that additionally provides a sealing seam extending along the entire circumference of the packaging tray between the top film and the packaging tray after and / or during the skin sealing process. This ensures, at a minimum, that the top film is tightly connected to the packaging tray at every point, and that any existing wrinkles are virtually ironed out, at least in the area of ​​the sealing seam, and cannot lead to leaks. The packaging also often looks more visually appealing.

[0026] Yet another object of the present invention relates to a method for producing a skin packaging, in which: a packaging tray with a packaged product (16) is provided, a top film web is pulled into a recess of an upper tool by means of negative pressure, a product vacuum is applied in the region of the packaging tray and the packaged product,

[0027] - the upper film web is then formed in the direction of the packaging trough filled with a packaging product, which encloses the packaging product and connects to the packaging trough over a large area, and in which, in order to form the upper film web in the direction of the packaging trough filled with a packaging product, the negative pressure between the indentation and the upper film web is first reduced only in a central area, in particular by ventilating.

[0028] The statements made regarding this subject matter apply equally to the other subject matters of the present invention, and vice versa. Features disclosed in connection with this subject matter of the present invention can be combined with other subject matters, and vice versa.

[0029] The method according to the invention is used to produce skin packaging, i.e. packaging in which the upper film tightly encloses the packaged goods and bonds to the packaging tray over a large area. Large area in the sense of the invention means that the sealing area is larger than when sealing with a sealing frame. According to the invention, the upper film is formed in an upper tool of the sealing station which has an indentation. Upstream of the upper tool, the upper film is not pre-formed with respect to its direction of movement but is flat. It is only in the upper tool that deformation and then, preferably, full-surface heating of the section of the upper film that becomes part of the resulting packaging takes place. For deformation, a vacuum is generated between the upper tool, in particular the indentation, and the upper film, which pulls the upper film towards the indentation of the upper tool, in particular until it rests against it.

[0030] Preferably, a certain waiting time is provided before the negative pressure is applied, which pulls the top film into the indentation.

[0031] During and / or after the top film has been formed in the upper tool, a negative pressure is created between the top film and the packaging tray and preferably also below the packaging tray, the so-called product vacuum. As soon as or after the top film has been formed in the indentation, the negative pressure above the top film is reduced and the negative pressure below the top film draws the product towards the packaged item and at least partially encloses it in a form-fitting manner. Since the top film has preferably been heated in the indentation of the upper tool, it bonds over a large area and in a material-to-material bond with the packaging tray, preferably along the entire surface of the packaging tray facing the top film that is not covered by the packaged item. This seal is preferably peelable.

[0032] Preferably, a seal is additionally created between the top film and the packaging tray using a sealing frame and / or the upper tool. This seal preferably extends along a horizontal surface along the edge of the package. This seal can be peelable.

[0033] According to the invention, the negative pressure between the indentation and the top film is only locally reduced in the central area of ​​the indentation, while the pressure in the remaining areas required to form the top film and / or maintain contact between the indentation and the top film is not reduced. Only after a certain period of time has elapsed and / or a certain reduction in the negative pressure has occurred in the central area is the remaining volume between the indentation and the top film, the edge area, also ventilated.

[0034] The negative pressure for forming the upper film is preferably <50, preferably 10-20 mbar. A preferred time period is <1 second, particularly preferably <0.5 seconds, and even more preferably <0.25 seconds. Preferably, the ventilation of the remaining volume between the indentation and the upper film is initiated when the negative pressure in the central region is reduced by preferably >40, particularly preferably >60, even more preferably >100, and most preferably >200 mbar.

[0035] Preferably, the volume flow during ventilation, especially in the central area, is controlled. Initially, the volume flow is lower and then increased, preferably under pressure control.

[0036] The ventilation of the remaining volume between the indentation and the top film is preferably carried out as quickly as possible without any throttling and preferably in

[0037] Essentially, particularly preferably exclusively via gas passages in the rest of the

[0038] Volume between the indentation and the top film, the so-called edge area.

[0039] Preferably, the top film first contacts the central area of ​​the packaging cavity and then the rest. The central area of ​​the packaging cavity is the geometric center of the area covered by the indentation of the top film. It is preferably located below the highest point of the indentation.

[0040] Preferably, after ventilating the central area, the top film forms an M-shape and / or has an indentation that curves away from the indentation

[0041] The sequence of negative pressure reduction in the central area and in the peripheral area is pressure and / or time controlled.

[0042] The invention is explained below with reference to Figures 1-6. These explanations are merely exemplary and do not limit the general inventive concept. These explanations apply equally to all inventive subject matter of the present invention.

[0043] Figure 1 shows the packaging machine according to the invention.

[0044] Figure 2a shows the forming of the top film. Figure 2b shows the venting during the production of a skin-

[0045] State-of-the-art packaging processes.

[0046] Figures 3a and b show two alternatives of the upper tool according to the invention.

[0047] Figures 4a and 4b show the “skinning” of the top film

[0048] Figure 5 shows an optional sealing of the edge area of ​​the packaging

[0049] Figures 6 and 7 show the “skinning” of the top film

[0050] Figure 1 shows an embodiment of the packaging machine 1 according to the invention, which here has a thermoforming station 2, a filling station 7, and a sealing station 15. A material web 8, here a plastic film web 8, the so-called base material web, is drawn from a supply roll and transported, preferably intermittently, along the packaging machine according to the invention from right to left. During each cycle, the material web 8 is transported further by one format length. For this purpose, the packaging machine has two transport means, in this case two endless chains, which are arranged to the right and left of the material web. Both at the beginning and at the end of the packaging machine, at least one gearwheel is provided for each chain, around which the respective chain is deflected. At least one of these gearwheels is driven.The gears in the inlet area 19 and / or in the outlet area can be connected to one another, preferably by a rigid axle. Each transport means typically has a plurality of clamping means that clamp the material web 8 in the inlet area 19 and transmit the movement of the transport means to the material web 8. In the outlet area of ​​the packaging machine, the clamping connection between the transport means and the material web 8 is released again. In the optional thermoforming station 2, which has an upper tool 3 and a lower tool 4 that has the shape of the packaging tray to be produced, the packaging trays 6 are formed into the film web 8. The lower tool 4 is arranged on a lifting table 5, which, as symbolized by the double arrow, is vertically adjustable. Before each film feed, the lower tool 4 is lowered and then raised again.Further along the packaging machine, the packaging troughs are then filled with the packaging goods 16 in the filling station 7. If the base material web is not deep-drawn, the packaging goods are placed on the flat base material web. In the subsequent sealing station 19, which also consists of an upper tool 12 and a vertically adjustable lower tool 28, an upper film 14 is firmly attached to the material web 8 by sealing. In the sealing station, the upper tool and / or the lower tool are also lowered or raised before and after each film transport. Before the upper film 14 is sealed to the base film 8, a certain negative pressure, the so-called product vacuum, is present in the filled packaging trough, with which in this case the upper film 14 is pulled onto the packaging trough 8 and bonds with it over a large area.Further along the packaging machine, the finished packages are separated, which in this case is done by the cross cutter 18 and the longitudinal cutter 17. In this case, the cross cutter 18 can also be raised or lowered using a lifting device 9.

[0051] The sealing tool comprises a shaping and preferably replaceable upper tool 12 with a recess 27, which forms a dome into the flat upper film. For this purpose, a vacuum is applied between the upper tool and the upper film, which presses the upper film against tool 12 and / or draws it into the recess 27 of the upper tool. Furthermore, the upper tool is heated at least in sections. As soon as the previously preferably unheated upper film comes into contact with the upper tool, it is heated to the desired temperature, which promotes its deformation and subsequent sealing to the packaging cavity.

[0052] The upper film 14 is preferably neither heated nor preformed before entering the sealing station 15. Furthermore, the upper film is preferably not guided in the area of ​​the sealing station or upstream of it.

[0053] Figure 2a shows processes in the sealing station in the method according to the invention. As soon as the packaging tray 6 and the upper film 14 are in the sealing station, the upper tool 12 and the lower tool 28 are moved together and sealed in their edge region 30a, and the upper film and the packaging tray are clamped. Then, as symbolized by the arrow 13, a vacuum is created between the upper tool 12 and the upper film, which draws the upper film towards the upper tool via gas vents (not shown). The gas vents are located on the entire surface of the indentation 27, so that the upper film rests against the indentation 27 of the upper tool 12, which is symbolized by the arrows 10. The preferably heated upper tool transfers its heat to the upper film, which until then has preferably not been heated, at most by radiant heat in the sealing station.During or after the forming of the top film, a negative pressure 24, the so-called product vacuum, is generated in the space between the top film 14 and the packaged goods 16, which preferably corresponds to the negative pressure above the top film.

[0054] Reference is made below to Figure 2b. As soon as the top film has been sufficiently heated or formed, or after an additional waiting time, the space above the top film is ventilated, i.e. at least the existing negative pressure is reduced to ambient pressure. Figure 2b shows the processes according to the prior art. This takes place, as shown by the arrows 10, by gas, in particular ambient air, flowing in across the entire surface of the indentation simultaneously. This increases the pressure between the indentation 27 and the top film 14, so that the latter is pressed towards the product and the free surface of the packaging tray. The heated top film 14 encloses the packaged goods in a form-fitting manner and bonds materially to the free surface of the packaging tray.

[0055] Figures 3a and b each show an embodiment of the upper tool according to the invention. The transport direction of the material webs 8, 14 passes through the plane of the paper. This also applies to all subsequent figures. Essentially, reference can be made to the explanations for Figure 2a. As already explained, the indentation has a plurality of gas passages 26, for example bores, which are preferably distributed equidistantly over the inside of the indentation 27. These gas passages can be connected optionally to a vacuum source (not shown) or to a ventilation source (not shown), for example the ambient air. By means of the gas passages 26, the upper film is sucked into the indentation until it rests against it. At the same time or afterwards, a vacuum 24, the so-called product vacuum, is generated in the space between the lower material web 8 and the upper film 14.In the illustration according to Figures 3a and 3b, a distance is shown between the tools 12 and 28, and the product vacuum is drawn between the two materials 8, 14. The person skilled in the art will recognize that these tools can also lie next to one another and / or that the product vacuum can also be drawn via a recess in the material web 8. In the space between the lower material web 8 and the lower tool 28, a vacuum 22 is preferably also generated, in particular to prevent the packaging tray from deforming due to the product vacuum. As already explained in detail above, the gas passage channels can be divided into at least two, here exactly two groups, which can be connected independently of one another to a vacuum and / or ventilation source. For this purpose, the tool according to the invention has, for example, a chamber 21 in the central region of the indentation or the tool and a chamber 23 in the edge region.The pressure in the respective chambers can be adjusted independently of one another. The chamber 21 in the central region is assigned to the gas channels in the central region 32 of the indentation and applies the desired negative pressure to these and / or ventilates them. The same applies analogously to the chamber 23 in the edge region. The chambers 21, 23 can each be connected independently of one another to a negative pressure source 13 and / or a ventilation source. Each chamber has a base, here the inner wall of the indentation, at least one circumferential wall and a lid. The base area of ​​the chamber in the central region, seen here from above, is preferably square, rectangular, polygonal, oval or circular. The chamber in the edge region preferably extends in a ring around the central region.

[0056] In the present case, two troughs and two packaged goods are shown. These can be part of a package, which is subsequently separated. A preferred alternative of the present invention is also to use one recess for the production of multiple packages, in this case two packages, each containing one product. The two packages are sealed together and then separated from each other downstream.

[0057] The example according to Figure 3b essentially corresponds to the example according to Figure 3a, so that reference can be made to the explanations for Example 3a. In the present example, valves 29, 34, 35 are shown, each of which can preferably be controlled individually. These are preferably not on / off valves, but rather valves with which the gas flow can be adjusted. The valves shown allow the chamber to be optionally connected to a vacuum source and a ventilation source. Valve 35 is used to adjust the vacuum between the material web 8 and the lower tool 28. Those skilled in the art will understand that one valve 34 may be sufficient.

[0058] Figures 4a and 4b show the method according to the invention, in particular the venting of the volume 25 between the indentation and the upper film, the so-called upper vacuum. As shown by the arrow in Figure 4a, the group of gas passages 26 in the central region 32 of the indentation 27 is vented first, for example by connecting the valve 29 to the environment. This reduces the negative pressure of the upper vacuum 25 and, due to the pressure difference to the product vacuum 24, the upper film 14 in the central region is curved towards the packaging tray, while the upper film in the edge region of the indentation still remains in contact with it because the valves 34 are not yet vented. The upper film preferably forms a balloon-shaped region and will particularly preferably adhere to the packaging tray in the central region. The product vacuum can be kept constant or reduced.At a later time, for example in a time- and / or pressure-controlled manner, the edge region is then also ventilated, which is shown in Figure 4b by the arrows 20, by air flowing through the valve(s) 34. The valve 29 is preferably closed. When ventilated completely, the top film lies flat against the product and the surface of the packaging tray facing the top film. The movement of the top film in the direction of the packaging tray forces the gas in the product volume, preferably out of the packaging in the direction of its edge. The ventilation of the central region can start comparatively slowly and then increase, which can be controlled by the valve 29. The volume flow, in particular of ventilation gas, can be time- and / or pressure-controlled, with the pressure sensor for this purpose preferably being provided in the chamber 21 in the central region.As soon as a certain time window has elapsed since the start of venting the central area and / or as soon as the negative pressure has been reduced by a certain amount toward ambient pressure, venting is initiated through the edge area of ​​the holes 26. This venting then preferably occurs as quickly as possible, particularly preferably with a fully open valve 34. The valve 29 is preferably closed when venting through the holes in the edge area.

[0059] In the illustration according to Figure 5, the lower tool has been raised, as indicated by arrow 31, to close the gap between the upper tool 12 and the lower tool 28. This can be done, for example, to create a sealing seam, for example, in the edge area of ​​the package. Those skilled in the art will understand that this gap can also be closed from the outset, i.e., also in the examples according to Figures 3a, 3b, 4a, and 4b.

[0060] Figure 6 shows the chambers in a plan view. The chamber 21 in the central region 32 is clearly visible, which in the present case has a rectangular base area. The chamber for the group of gas passages 26 in the edge region 33 extends annularly around the chamber of the central region. Those skilled in the art will understand that other base area shapes are also possible. In the preferred embodiment according to Figure 7, a bypass 36 is provided between the two chambers, which allows the entire volume of the indentation to be evacuated by connecting the chamber of the central region to a vacuum source. In the frame between the chambers 21, 23 in the middle tool, at least one opening is provided, which is closed like a valve with a membrane. The bypass opens by a movement of the membrane as soon as the vacuum is drawn and / or the negative pressure in the chamber 21 of the central region has reached a threshold value.

[0061] List of reference symbols:

[0062] 1 packaging machine

[0063] 2 forming station, deep-drawing station

[0064] 3 Upper tool of the deep drawing station

[0065] 4 Lower tool of the deep drawing station

[0066] 5 Lifting table, carrier of a tool of the sealing, deep-drawing station and / or the cutting device

[0067] 6 packaging tray

[0068] 7 filling station

[0069] 8 Material web, base material web, base film web

[0070] 9 Lifting device

[0071] 10 Forms, stretching the top film, applying it to the product and the packaging tray

[0072] 11 Sealing lower tool of the sealing station

[0073] 12 Upper tool of the sealing station, sealing tool

[0074] 13 Vacuum source

[0075] 14 Top film web, skin film

[0076] 15 Sealing station

[0077] 16 Packaging goods

[0078] 17 longitudinal cutters

[0079] 18 cross cutters

[0080] 19 Inlet area

[0081] 20 Ventilation and / or overpressure source

[0082] 21 Chamber in the central area

[0083] 22 sub-vacuum

[0084] 23 chamber in the peripheral area

[0085] 24 Product vacuum

[0086] 25 upper vacuum

[0087] 26 Gas passage, recess, bore

[0088] 27 indentation

[0089] 28 Lower tool

[0090] 29 Valve for the central area chamber

[0091] 30 Surrounding housing / clamping tool of the sealing station

[0092] 30a Edge area / clamping area of ​​the surrounding housing

[0093] 31 Stroke of the lower tool

[0094] 32 Central area, sub-area, peripheral area, valve for the chamber of the peripheral area, valve for the sub-vacuum bypass

Claims

Patent claims:

1. Upper tool (12) for a sealing station of a packaging machine, which has a recess (27) with which a top film web (14) can be formed and with a plurality of gas passages (26) which are provided along the recess and which can be connected to a negative pressure, positive pressure and / or ventilation source (13, 20), characterized in that gas passages can be divided into at least two groups which can be connected independently of each other to the negative pressure, positive pressure and / or ventilation source (13, 20).

2. Upper tool (12) according to claim 1, characterized in that it has chambers (21 , 23) which are each connected to the negative pressure, positive pressure and / or ventilation source (13, 20) and each to a group of gas passages.

3. Upper tool (12) according to one of the preceding claims, characterized in that a group and / or a chamber (21) is provided in a central area (32), in particular the recess (27).

4. Upper tool (12) according to claim 3, characterized in that a further chamber (23), in particular in an annular form, extends around the chamber (21) in the central area.

5. Upper tool (12) according to one of the preceding claims, characterized in that it has a pressure sensor, in particular in the central area.

6. Packaging machine in which a packaging trough (6) is filled with a packaging item (16) in a filling station and which has a sealing station in which the packaging item is enclosed with a top film at least substantially in a form-fitting manner and the top film connects with the packaging trough, wherein the sealing station has an upper tool (12) according to one of the preceding claims.

7. Method for producing a skin package, wherein: a packaging tray (6) is provided with a packaged item (16), a top film web (14) is drawn into a recess (27) of a top tool (12) by means of a vacuum (13, 25), a product vacuum (24) is created in the area of ​​the packaging recess (6) and the packaging item (16), - the top film web (14) is subsequently formed in the direction of the packaging recess (6) filled with a packaged item (16), thereby enclosing the packaged item and bonding with the packaging recess over a large area, characterized in that, for forming the top film web (14) in the direction of the packaging recess (6) filled with a packaged item (16), the negative pressure (25) between the indentation (27) and the top film web (14) is first reduced only in a central area (32), in particular by aeration. Method according to claim 7, characterized in that the negative pressure in the area between the indentation (27) and the top film (14) is then completely and / or fully reduced, in particular by aeration.A method according to claim 8, characterized in that complete aeration takes place in the edge region of the indentation (27). A method according to any one of claims 7-9, characterized in that the reduction of negative pressure in the central region takes place in multiple stages. A method according to any one of claims 7-10, characterized in that the upper film initially rests in the central region of the packaging recess. A method according to any one of claims 7-11, characterized in that the sequence of negative pressure reduction in the central region (32) and in the edge region (33) is pressure- and / or time-controlled.

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