Package making – Methods – Conforming by stretching or shrinking of cover over contents
Reexamination Certificate
1999-04-15
2001-11-27
Smith, Scott A. (Department: 3721)
Package making
Methods
Conforming by stretching or shrinking of cover over contents
C053S434000, C053S556000, C053S512000
Reexamination Certificate
active
06321513
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for packaging articles and/or objects and a device for carrying out said method.
2. Description of the Related Art
According to the prior art, articles or objects of the most different kinds are packaged with various packaging materials.
According to the prior art, articles or objects, including foods, are packaged with packaging materials which are formed elastically. On account of the packaging methods belonging to the prior art, the fields of application for these packaging methods, in which the articles or objects are packaged with elastically formed packaging materials, are very limited.
The packaging methods belonging to the prior art for a packaging of an article or object with a elastic packaging material are executed on the one hand with the aid of stretchers.
Hereby an expansion of the elastic packaging material is attained by means of the varying running speeds of rollers between which the elastic packaging material is guided. After the expanding of the packaging material, the article to be packaged is placed on or in the packaging material, and the elastic packaging material contracts through its restoring forces.
This method belonging to the prior art has the disadvantage that damage to the packaging material may occur through the expanding of the packaging material by means of the rollers.
The method belonging to the prior art is moreover very cost-intensive, as the mechanical expansion has to be executed very quickly on the one hand and high forces have to be generated for the expansion on the other.
Moreover, the packaging method belonging to the prior art has the disadvantage that it is hardly possible to pull the packaging material in its length and simultaneously in its width by means of the stretchers.
A further disadvantage of this method is that the expansion forces to be generated pull the elastic packaging material into a smooth, monoplane shape and thus a simultaneous shaping of the packaging material is not possible. For example, the packaging material formed as a monoplane foil becomes larger during expansion. It always remains, however, a monoplane foil and does not form a shape, for example a sleeve or the like.
A further disadvantage is that the force applied for expanding the elastic packaging material always acts on the packaging material only linearly at the contact points between the rollers. With this method, the entire force needed to expand the total surface of the packaging material is applied between two pairs of rollers at one point. This very often results in damage.
On the other hand, the prior art includes a packaging method (DE 39 08 585 C2) in which, for example, meat is packaged in elastic packaging material. This method belonging to the prior art provides for rods which are located parallel or approximately parallel or else conically to one another in a circle or approximately a circle. On the outside of the circle formed by the rods, the elastic packaging material is located In the form of a sleeve or bag. The meat is pushed through between the rods. For the expanding of the packaging material there are now two possibilities:
Either the packaging material is already placed in pre-expanded state on the rods, i.e. the packaging material is expanded by mechanical means which act on the rods, or the packaging product must induce an expansion of the elastic packaging material during the pushing through the rods by forcing the rods and the packaging material apart.
When pushing a joint of meat, for example, along the rods, the packaging material is pulled down by the rods. The packaging foil is applied to the meat with a pressure acting from all sides on the meat.
With this method it is indeed possible for the packaging foil to have a shape (sleeve shape).
However, this method belonging to the prior art has the disadvantage that the packaging method is not suitable for many products because the expansion of the rods and of the packaging material has to be induced by the product. One example to be given in this context is the packaging of diapers, as the diapers, due to their deformability, are not in a position to force the rods and the packaging material apart in a defined way. On being pushed through, the diapers are compressed by the confronted pressure instead of forcing the rods apart.
If the expanding of the packaging material is to be induced by the mechanical means acting on the rods, so that diapers, for instance, can be packaged, very complex mechanical constructions are necessary for this purpose.
A further disadvantage of this packaging method belonging to the prior art is that the expansion means used are always inside the packaging during the packaging procedure and can thus severely impede the packaging procedure.
SUMMARY-OF THE INVENTION
Moreover, this method belonging to the prior art has the disadvantage that it can be executed only very slowly.
The technical problem underlying the invention is in specifying a method for the packaging of articles and/or objects, including foods, according to which the articles and/or objects can be packaged by a simple means in a elastic packaging material, with which the elastic packaging material is expanded in the packaging procedure, and in which the packaging material is strained as uniformly as possible and thus only little per area unit during the packaging procedure, in order to prevent damage to the packaging material. Furthermore a method is to be specified in which the expansion means for the elastic packaging material do not impede the packaging procedure. Moreover, the packaging material is to be expanded uniformly and/or in a defined manner so that it clings after the packaging under a desired pressure to the commodity to be packaged. A packaging method is to be specified in which the elastic packaging material is expanded in such a way that the elastic packaging material assumes predefined shapes in order to meet the differing demands of various articles or objects to be packaged. Moreover, a packaging method is to be specified with which it is possible to package articles or objects from the most diverse areas. Moreover, a device for carrying out the method is to be specified.
In accordance with the method according to the invention, elastic packaging material is exposed to an atmospheric differential pressure in a receptacle, A partial vacuum is generated in the receptacle between the packaging material and the receptacle wail. The external air pressure acts on the other side of the packaging material. By this means the elastic packaging material is expanded and the commodity to be packaged is then placed on and/or under or in the expanded packaging material. The partial vacuum is then released. The elastic packaging material is restored, at least to the extent that is clings at least partially to the commodity to be packaged.
The elastic packaging material is made, for example, of polyolefin elastomer or polyurethane elastomer and of monoplane configuration. It is possible to use a single-ply or multi-ply foil. In the case of a multi-ply foil, at least one foil ply can consist of another material. For example, the combination with polyvinyl dichloride (PVDC) or ethylene vinyl alcohol (EVOH) is possible in order, for example, to increase the gas impermeability of the foil.
In the method according to the invention, foils which have a ply thickness of between 20 and 200 &mgr;m are used with preference. The expandability in the elastic area of the foil is advantageously between 30% and 400%. With most packagings it is practicable to work with an expansion of around 50% to 150%.
In accordance with the method according to the invention, the external air pressure acting on the entire surface of the packaging material acts as an expansion force in that a partial vacuum is generated on the opposite side of the packaging material. Depending on how great the partial vacuum is, the external air pressure acts as an expansion force between 0 bar and almost 1 bar per cm
2
of the packaging mate
Collard & Roe P.C.
Pi-Patente Gesellschaft mit beschränkter Haftung (GmbH) Entwickl
Smith Scott A.
Tawfik Sam
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