Package making – With contents treating – Reshaping
Reexamination Certificate
2000-04-19
2001-07-31
Lazarus, Ira S. (Department: 3721)
Package making
With contents treating
Reshaping
C053S525000
Reexamination Certificate
active
06266947
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for retroforming, or calibrating, a sealed packaging container which is manufactured from flexible packaging material and which contains flexible, incompressible contents. The present invention also relates to an apparatus for retroforming, or calibrating, sealed packaging containers filled with liquid contents and of the type which are manufactured from flexible packaging material.
BACKGROUND ART
It is common practice in the food industry to pack liquid contents such as juice or milk in packaging containers of single-use disposable type which are manufactured from a flexible, liquid-tight packaging material. The substantially parallelepipedic packaging containers which are marketed under the brand name Tetra Brik ® are described in greater detail in European Patent No. EP 91712, to which reference is now made, and are thus manufactured from a flexible packaging laminate which comprises a carrier or core layer of fibre material, for example paper, which is coated on each side with relatively thin layers of thermoplastic material, normally polyethylene. The packaging laminate may also include further material layers, such as barrier layers of metal or other barrier materials in order to provide improved protection against light or oxygen gas when particularly sensitive products are to be packed.
In the manufacture of the above-outlined prior art packaging containers, a packing or filing machine is employed which stepwise reforms a preferably web-shaped packaging laminate into individual, filled packaging containers. In order to facilitate the reforming process, the packaging laminate is provided with a pattern of fold or crease lines which are formed by pressing of the packaging laminate between rollers with cooperating ridges and depressions which, above all because of softening of the fibre layer, impart to the material a tendency to be folded along the weakened, linear areas created in this process. The reforming of the original, substantially cushion-shaped filled and sealed packaging containers into parallelepipedic form will hereby be facilitated. The so-called final forming above all comprises flat-pressing, inward folding and sealing of formed corner flaps to the outside of the packaging container, so that a substantially parallelepipedic configuration is achieved. Since, principally for economic reasons, attempts are made in the art to minimise the quantity of material included in the packaging laminate, the packaging laminate itself is relatively thin, with the result that the difference in folding tendency between the parts of the laminate provided with fold or crease lines and the unaffected parts is relatively slight. Consequently, the reforming of the packaging laminate into packaging containers and, in particular the so-called final forming operation may result in a packaging container which not always obtains the desired, well-defined edges and comers but tends to display a more rounded transitional area between the different wall surfaces of the packaging container disposed at angles to one another. A more undefined configuration further entails the disadvantage that the packaging container will, in the finished state, be perceived by the consumer as more markedly yielding and unstable, which may impede the consumer's handling of the packaging container, primarily in connection with pouring of the contents from the container.
The method and the apparatus according to the present invention may naturally also be employed in other, for instance prismatic configurations of packaging containers which are manufactured by folding and sealing of flexible packaging material.
There is thus a general need in the art to realise a packaging container of the above-outlined type possessing well-defined—or calibrated—configuration and improved steadiness and stability. With a view to realising this object, attempts have been made in the art to modify the packaging laminate by incorporating layers of different material types and properties, but this has however most generally entailed that the packaging laminate becomes more expensive. Trials have also been carried out with different types of crease or weakening lines, with the intention of realising a more manifest weakening of the material so that folding and forming are facilitated, but no tangible improvement has been achieved. In order to obtain a packaging container possessing well-defined or calibrated configuration and improved stability, one option which has been indicated in the art is to increase the thickness of the packaging laminate and, in particular, the fibre layer, which naturally entails increased costs and, as a result, has been put into practice to only a limited extent.
SUMMARY OF THE INVENTION
One object of the present invention is thus to realise a method of retroforming or calibrating a packaging container which is manufactured from flexible packaging material and contains preferably liquid contents, the method making it possible to obviate the above-outlined drawbacks and to realise a packaging container possessing considerably improved steadiness and stability as well as a better defined contour.
A further object of the present invention is to realise a method which makes it possible, by a simple and uncomplicated process, to calibrate a packaging container so that it assumes its predetermined configuration with a high degree of accuracy.
Yet a further object of the present invention is to realise a method of imparting to a packaging container sharp and well-defined edge lines and corners, whereby the appearance and stability of the packaging container are improved.
The above and other objects have been attained according to the present invention in that a method of the type described by way of introduction has been given the characterizing feature that the packaging container is surrounded by a forming device adapted to the desired final form of the packaging container, the forming device comprising forming parts which are moved towards one another so that the free space available for the packaging container is briefly reduced.
A further object of the present invention is to realise an apparatus for calibrating sealed packaging containers which are manufactured from flexible packaging material and are filled with liquid contents. The apparatus according to the present invention should further be of simple, dependable construction and be designed so as to be able to be integrated into existing packing machines for the production of, for example packaging containers of the Tetra Brik ® type.
Still a further object of the present invention is to realise an apparatus of the above-outlined type which is economical to manufacture and operate and at the same time makes possible the reliable final forming or calibration of produced packaging containers.
The above and other objects have been attained according to the present invention in that an apparatus of the type described by way of introduction has been given the characterizing features that it comprises a forming device consisting of movable forming parts which are displaceable between an open and a closed position in which a cavity defined by the forming parts has a volume which amounts to between 100 and 110 per cent of the theoretical minimum volume of a processed packaging container.
The method and the apparatus as, devised according to the present invention make for a final forming or calibration of per se known packaging containers, which imparts to the packaging containers a considerably better defined configuration and increased steadiness and stability and, as a result, improved consumer friendly handling. As a result of the temporary volume reduction undertaken in connection with the calibration process according to the invention, the packaging container is obliged to adapt to the inner configuration of the forming device, with the result that, in particular along the edge lines and corners of the container, the fibre layer of the material is given more dearly defined folds.
REF
Burns Doane Swecker & Mathis L.L.P.
Huynh Louis K.
Lazarus Ira S.
Tetra Laval Holdings & Finance S.A.
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