DK2722281T3

DK2722281T3 - A method of gas tightly wrapping articles in a foil adjacent the articles which can be deep-drawn using vacuum

Info

Publication number: DK2722281T3
Application number: DK13188316.7T
Authority: DK
Inventors: Seggern Jörg von
Original assignee: Jörg Von Seggern Maschb Gmbh
Priority date: 2012-10-17
Filing date: 2013-10-11
Publication date: 2017-04-24
Also published as: PL2722281T3; EP2722281A3; DE102012020359A1; LT2722281T; EP2722281B1; EP2722281A2; HUE033769T2; EP2845809A1; PT2722281T; ES2622454T3

Description

The invention relates to a method for the gastight packaging of objects using a film material fitting tightly on the objects using a vacuum, the object being placed in a tray and a film that can be deep-drawn being attached to the tray for sealing.

Methods of the abovementioned species are used for packaging objects in gastight manner. Such objects may be for example inorganic products such as tools or stationery, which are kept for sale in the markets in corresponding packaging. Particularly when a vacuum is used to deep-draw the film that is welded to the tray, the objects may be organic products, such as foodstuffs. Meats and sausages in particular are packaged using this type of packaging in order to ensure the smallest possible gas volume in the interior space of the packaging.

Known methods are known from DE 102 37 933 A1 for example.

In the known methods an object is placed in a tray and the film that can be deep-drawn is then welded to the tray. After the deep-drawing operation, the film is cut to the size of the tray, and this often involves cutting of the film and tray in one step, e.g., if the tray slips. This may disadvantageously result in sharp tray edges. A further disadvantage is that this subsequent cutting is performed on film that is still heated for the welding process. The film in its heated state has a soft consistency so that it is only able to provide minimal resistance to a cutting knife. This results in jagged edges causing unattractive creasing and warping of the cut film edges.

The object underlying the present invention is to provide a method which makes it possible to package objects in attractive, gastight packaging.

This object is solved according to the invention in that in order to form the packaging a tray having at least one peripheral edge is used, the film that can be deep-drawn is placed on the peripheral edge in gastight manner, and then only the film that can be deep-drawn is cut to a size smaller than that of the peripheral edge. A tray having a peripheral edge is also used in the method according to the invention. However, this peripheral edge is not damaged during packaging of an object, so that this rim may be provided in advance with an attractive, grippable edge or other design. The peripheral edge of the tray is protected according to the invention in that only the film that can be deep-drawn is cut to size after it has been applied to the peripheral edge.

Therefore the processing sequence in the method of the present invention is the same as that of the prior art. The film is applied first and then cut to size. This has the advantage that cutting of the film takes place in a late processing step. Also, the peripheral edges of the tray are not cut, since cutting of the film takes place in such a manner that the cutting tools provided for this purpose do not come into contact with the tray. A rim structure of the tray is therefore maintained and sharp cut edges advantageously do not occur.

According to a first further refinement of the method according to the present invention, the film that can be deep-drawn is welded onto the peripheral edge. The welding creates a secure, gastight bond between the film and the tray.

According to another refinement of the invention, it is provided that a thermal load is applied to the film that can be deep-drawn before the welding step. The film undergoes pre-expansion due to the heating of the film. The film also becomes warmer so that it responds well to a subsequent deep-drawing operation. In this context, it may be provided that a vacuum is applied in such manner as to expand the surface area of the film that can be deep-drawn before the welding step. This prior expansion of the film enables the film that can be deep-drawn to advance into constricted protrusions and undercuts during the deep-drawing process. Since multiple trays are typically sealed simultaneously in such an apparatus, the deep-drawable material needed for sealing a tray is drawn off from a larger reserve. While the film that can be deep-drawn is being prepared, this reserve is still uncut to enable material to be drawn off in an uninterrupted web. According to the invention, the film that can be deep-drawn is not cut until it has been welded onto a tray rim.

To be able to perform the deep-drawing operation, a further refinement of the invention provides for a vacuum to be created in the region surrounding the tray. The vacuum enables pressure conditions to be set that cause the film to be deep-drawn when a pressure gradient if formed. The deep-drawing operation causes the film to fit tightly on the object to be packaged as well as on areas of the tray not occupied by the object, according to the “skin” method.

For the purposes of a further refinement of the method according to the invention, it is also provided that an overpressure may be formed in the region surrounding the film that can be deep-drawn on the side facing away from the tray. The side of the film that can be deep-drawn facing away from the tray is capable of sustaining the overpressure that is applied to this side. This supports the vacuum that is applied to the other side of the film that can be deep-drawn in order to achieve the tightest possible fitting of the film that can be deep-drawn on the object to be packaged. This tight fit advantageously ensures not only that the object is fixed in place but also, for example in the case of objects containing meat, that liquids in the meat are not able to escape. Thus, marinades or the meat's own juice can be contained in the product so that the product does not dry out and stays fresh despite the longer shelf life achieved by the packaging. The overpressure may be generated quickly to achieve faster and tighter fitting of the film.

Besides the supporting surface for at least one tray and besides the sealing tool for the film that can be deep-drawn, a device designed for the method has at least one cutting device for the film that can be deep-drawn, which cutting device can be moved to a height above a peripheral edge of the tray at which only the film that can be deep-drawn is cut.

According to the method of the present invention, the film must first be applied to the tray and then cut to size. Due to this procedure, a separate cutting station for the film is no longer necessary. According to the present invention, it may be assigned to the device since the film is cut immediately after it has been sealed or welded.

The cutting device preferably includes knife blades which are able to successfully cut the film that can be deep-drawn.

It may further be provided that the cutting device is spatially assigned to the sealing tool. This spatial assignment makes it possible for sealing and cutting to take place in quick succession. The cutting device and sealing tool are spatially assigned to one another, both assemblies are structurally independent of one another to enable the work steps of sealing and cutting to size to be performed separately.

The cutting device is able to move around the sealing tool. If the sealing tool has a rectangular design, for example, knife blades of the cutting device are able to move around this sealing tool like a frame. After the sealing tool is applied to the film, the knife blades configured in a frame-like manner cut the film to size.

With respect to the structural design of the device, a refinement provides for the supporting surface for the tray and/or the sealing tool to be constructed so as to be height-adjustable. Consequently, the supporting surface and the sealing tool are able to be moved towards and away from each other. The approaching motion is used to apply the sealing tool to the film that can be deep-drawn when the cutting tool is still at a distance from the peripheral edge of the tray.

Another refinement provides that the supporting surface has at least one supporting apparatus for the peripheral edge of the tray. The tray is able to be inserted in the supporting apparatus for the peripheral edge with the aid of the supporting surface. The peripheral edge is preferably positioned on this supporting apparatus so that it is ready for welding or sealing to the film that can be deep-drawn. The supporting apparatus supports the peripheral edge and forms a counter support for the sealing tool that is to be applied to the edge.

According to another refinement of the device, it is provided for a spacer plate to be arranged between the trays and the film that can be deep-drawn, which spacer plate can be placed on the supporting apparatus for the peripheral edge, wherein at least part of the peripheral edge remains free. This spacer plate provided according to the invention supports the cutting to size of the film that can be deep-drawn after it is welded or sealed onto the peripheral edge of the tray. This spacer plate may be placed for this purpose on the peripheral edges of the tray accommodated in the supporting apparatus. The top surface of the spacer plate now forms a plane which is above the peripheral edge. The film that can be deep-drawn may be placed on this plane, the film that can be deep-drawn is guided towards the sealing device with the spacer plate.

With regard to the method, it is provided that a vacuum is applied to the film that can be deep-drawn to stretch it before it is welded. With the spacer plate, the film is guided towards the sealing tool and held in place when the vacuum is applied to the film with the sealing tool. The sealing tool is preferably of concave design so that the film that can be deep-drawn is able to advance into the cavity when the vacuum is applied. The peripheral edges of the tray are kept free by the spacer plate. The other regions of the tray may also remain free so that the sealing tool may be applied to a large surface in order to weld the film that can be deep-drawn while simultaneously heating it for a subsequent deep-drawing operation. For this purpose, at least one opening able to be superposed over the container is preferably located in the spacer plate. This opening then has dimensions corresponding to the sealing tool.

When using this spacer plate with the openings, it is advantageous to spatially assign the cutting device to the sealing tool. When moving the sealing tool towards the film that can be deep-drawn, the cutting device may be moved in at the same time. The cutting device is then preferably able to be moved through the opening in the spacer plate like the sealing tool. The cutting tool is preferably decoupled from the sealing tool and spring-suspended. This decoupling makes it possible for the sealing tool initially to be moved closer to the tray than the cutting tool. After this approach by the sealing tool, sealing may be performed between the film and tray. For this, the cutting tool is guided to the plane of the surface of the peripheral edge in a corresponding guide. The film that can be deep-drawn resting on the peripheral edge is cut, but in so doing the knife is not moved into the peripheral edge. The peripheral edge is undamaged.

For the purposes of a further embodiment of the device, it is also preferably provided that at least one overpressure line and/or a vacuum line passes through the sealing tool. The sealing tool is situated on the side of the film that can be deep-drawn facing away from the tray. An overpressure medium, e.g. air, may be supplied via the overpressure line that passes through the sealing tool in order to generate an overpressure preferably provided according to the method on this side of the film. The underpressure provided for according to the method is generated via the vacuum line. A package produced according to the method of the invention is characterized in that after placement of the film that can be deep-drawn on at least one peripheral edge of the tray, section of this rim are covered.

It is thus provided that the film placed on the peripheral edge does not completely cover said edge. The film may have an offset with respect to the outer edge of the peripheral edge so that it does not come into contact with said edge. It may instead be welded to a region of the peripheral edge at a distance from the outer border of the peripheral edge. This produces a clean weld seam.

In this context, a peripheral edge of the tray is always the region of the tray surface that peripherally surrounds at least one depression in the tray. The tray may have a single depression surrounded by one peripheral edge. But it is also possible for a plurality of depressions to be situated in one packaging, for example in the case of a plurality of yogurt pots. A separate film that can be deep-drawn may be assigned to each of these depressions and attached only to the peripheral edge surrounding the individual depression. As a result, the various depressions are not covered in their entirety with one film but instead a plurality of films is provided. This packaging has regions not covered by film between the individual depressions. Perforations may then preferably be introduced in these regions to facilitate separation of the individual packaging regions. In this case pull-off tabs of the film that can be deep-drawn may also moved from a position in the outer region of the total packaging to an inner region, e.g. to where the films that can be deep-drawn of a plurality of depressions are close to each another.

An exemplary embodiment of a device for performing the method of the present invention is displayed in the drawing. In the drawing:

Figs 1 to 9 show sectional views of a device for the gastight packaging of objects with film material fitting tightly on the objects in various processing situations during a packaging operation; and

Fig. 7a shows a larger scale representation of a detail in Fig. 7, and

Fig. 5a shows a larger scale representation of a detail in Fig. 9.

The device in the figures has a lower tool 9 and an upper tool 1. Lower tool 9 includes a supporting table 8 for two trays 6. Each of the trays 6 has a peripheral edge 10. Supporting tables 8 are set up on a height-adjustable frame 11.

Two sealing tools 2 are accommodated in upper tool 1. Upper tool 1 is designed to be height-adjustable as a single unit. Cutting devices 3 which are configured as knives surrounding sealing tools 2 are spatially assigned to sealing tools 2. Cutting devices 3 are accommodated in knife holders 12.

Figure 1 further shows a film that can be deep-drawn 4. Prior to being sealed onto peripheral edges 10 of trays 6, this film that can be deep-draw 4 is in a single piece.

The device has a spacer plate 5 between the film that can be deep-drawn 4 and trays 6. This spacer plate 5 has openings 13 that correspond with trays 6. A supporting apparatus is also assigned to supporting tables 8 in the region of lower tool 9. This supporting apparatus is formed by the top sections of lower tool 9. Depressions 14 into which peripheral edges 10 of trays 6 may protrude are created in the surface of lower tool 9 in the region of this supporting apparatus.

Figure 2 shows the state after the film that can be deep-drawn 4 has been brought up to upper tool 1. This approach is effected with spacer plate 5, which then presses the film that can be deep-drawn 4 towards the upper tool and holds it in place. The approach of the film that can be deep-drawn 4 is indicated by arrows 20.

Figure 3 shows that a vacuum line passes through the sealing tools 2. Air is suctioned out of sealing tools 2 in the direction of arrows 20. This causes the film that can be deep-drawn 4 to be pressed against the inner contours of sealing tools 2. These are convex in construction so that dome-like regions are created.

Figure 4 shows the state after lower tool 9 has been raised. Trays 6 are placed on the supporting apparatus of lower tool 9. The peripheral edges 10 thereof are supported by lower tool 9.

Spacer plate 5 is placed on lower tool 9. The film that can be deep-drawn 4 rests on spacer plate 5, upper tool 1 with sealing tools 2 and cutting devices 3 is moved towards the film that can be deep-drawn 4. The film that can be deep- drawn 4 expands into the sealing tools 2 and preheated. Cutting devices 3 remain at a distance from the film that can be deep-drawn 4.

Figure 5 shows that air is sucked from the region surrounding trays 6 through air ducts 15 (arrows 16). This creates a vacuum in the region surrounding trays 6.

In figure 6, cutting devices 3 are not moved as far as the peripheral edges 10 of trays 6. Sealing tools 2 are then used to weld the film that can be deep-drawn 4 onto the peripheral edges 10. Film 4 is heated at the same time in preparation for the deep-draw operation. The placement of the sealing tools 2 on the peripheral edges 10 of trays 6 is indicated by arrows 17.

Figures 7 and 7a then show the cutting of the film that can be deep-drawn 4 with cutting device 3. Cutting device 3 is brought up to the peripheral edge 10 of tray 6 in defined manner by knife holders 12. In this way, film that can be deep-drawn 4 is cut without damaging peripheral edge 10. The film 4 is cut to size before said film 4 is deep-drawn.

In Figure 8, air is fed through overpressure lines 18 which pass through upper tool 1 and sealing tools 2, which air cooperates with the underpressure that exists in the region of trays 6 to cause the warmed film that can be deep-drawn 4 to fit closely against the objects 7 located in trays . The objects 7 may be meat products, for example. A buffer gas may also be fed into the region of trays 6 (arrow 19).

Figure 9 shows the state of the device after ejection of trays 6. Upper tool 1 and lower tool 9 are separated again, spacer plate 5 is lifted away from trays 6. Scraps of the film that can be deep-drawn 4 remaining after cutting are removed. After this sealing operation, trays 6 may be removed from lower tool 9 which is then able to accommodate new trays 6. In this context, the device may function in cycles, e.g. with 6 cycles per minute.

The device may also be a sealing device, with which trays may be also be sealed using films that are not deep-drawn via the "skin" method. The same device may thus be used for different packaging types in which identical standardised basic packages such as trays 6 are used.

Film that can be deep-drawn 4 is cut to size, said film 4 is welded onto peripheral edges 10, and film 4 is deep-drawn preferably in a single cycle to shorten processing time.

Cutting devices 3 are not directed through the plane of the peripheral edges 10. Figure 9 shows that film that can be deep-drawn 4 is cut off cleanly and that a portion of peripheral edge 10 which is free of film 4 remains in the region of this peripheral edge 10. Cutting devices 3 do not cut off peripheral edge 10.

Film 4 fits tightly on the walls of container 6 and on objects 7 present in the depression of the container, as shown in Figure 9.

Claims

A method of gas tightly wrapping articles in a foil adjacent to the articles which can be deep-drawn using a vacuum and wherein the article is placed in a tray and the deep-drawn film is connected to the tray for closure of the latter, characterized by that a tray (6) with at least one peripheral rim (10) is used to form the package and that an overpressure is created on the side facing away from the tray (6) in a transition area of the deep-extendable film (4).

Method according to claim 1, characterized in that the film (4), which can be deep-drawn, is welded to the peripheral edge (10).

Method according to claim 1 or 2, characterized in that the deep-drawn foil (4) before being welded is subjected to a heat effect.

Method according to one of the preceding claims, characterized in that the foil (4), which can be deep-drawn, is subjected to a vacuum before it is welded, in a manner which expands the surface area.

Method according to one of the preceding claims, characterized in that a vacuum is applied in an area corresponding to the surroundings of the tray (6).