Plastic article or earthenware shaping or treating: apparatus – Preform reshaping or resizing means: or vulcanizing means... – Shaping surfaces per se
Reexamination Certificate
1999-05-24
2001-07-03
Gerrity, Stephen F. (Department: 3721)
Plastic article or earthenware shaping or treating: apparatus
Preform reshaping or resizing means: or vulcanizing means...
Shaping surfaces per se
C053S559000, C425S441000, C425S058000
Reexamination Certificate
active
06254375
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a matrix and a process for the production of a package trough having at least one undercut.
Packages, particularly for foods, are becoming increasingly important today. The foods are placed in a so-called package trough and the package trough is then closed with a covering film.
As a rule, the package troughs are semi-continuously produced in so-called deep drawing stations of packaging machines. To this end, a film from which the package trough is produced is fed over a matrix of the deep drawing station, fixed there, optionally heated and then deep-drawn into the matrix using pressure, for example. The matrix is then lowered and the finished package trough is released from the matrix. As soon as the matrix has been lowered such that it is beneath the freshly produced package trough, the latter is moved on by the length of one package trough. The matrix is then raised again and the next package trough is deep-drawn.
For the packaging industry, so-called stand-up packages are of very special interest because they do not lie flat on the shelf but stand upright and thus provide a large presentation surface. Stand-up packages do not rest on the underside of the package trough but stand on a narrow side part of the package trough, i.e. the covering film on this package is roughly perpendicular to the bearing surface on which the package stands. For these packages, the package trough must have, in addition to the cut edge, a second standing surface on which the stand-up package firmly stands. This standing surface can be realized, for instance, in the form of an undercut whose lowest point must be on roughly the same level as the cut edge and thus does not tip backwards when it stands on its side.
However, such an undercut creates difficulties during the mold release of the package trough from the matrix after deep drawing because the undercut of the package trough is pressed against the matrix when the latter is lowered, thereby being either dented or even destroyed.
Therefore, a number of attempts have been made to provide devices for the production of package troughs having an undercut wherein the undercut is not damaged during mold release. EP 0,538,570, for example, teaches that the matrix during release is guided not vertically downwards but parallel to the tilted side face of the undercut. In this way it is possible to produce package troughs having undercuts transverse to the direction of package trough feed. The disadvantage of this procedure is that the movement of the matrix during release can only be realized with a relatively complex drive. Furthermore, this device can only be used for producing package troughs having an undercut transverse to the direction of package trough feed.
SUMMARY OF THE INVENTION
The object is therefore to provide a device which allows the production of a package trough having at least one undercut and does not have the disadvantages of prior art.
According to the invention, said object is achieved by providing a matrix for the production of a package trough having at least one undercut, which matrix consists of one bottom part, two side parts oriented transversely and two side parts oriented parallel to the direction of package trough feed and on which at least one of the side parts oriented parallel to the direction of feed serves as a mold for the undercut, and on which this side part is fixed in its spatial position in relation to the machine frame whereas the other parts of the matrix are vertically lowerable.
The side part which serves as mold for the undercut tapers essentially from the top of the matrix towards the bottom.
Both of the side parts oriented parallel to the direction of feed serve preferably as a mold for an undercut so that a package trough having two undercuts can be produced. These side parts are then both fixed in their spatial position in relation to the machine frame.
In another preferred embodiment, the side parts which serve as a mold for the undercut are interrupted by one or more webs which do not taper downwards, so that no undercut is produced in the package trough at these points.
In yet another preferred embodiment, the side parts remaining unchanged in their position in relation to the machine frame have a surface with a low coefficient of friction on their top. This surface can be either polished or coated with Teflon or a similar material.
In order to deep-draw the film with a vacuum into the matrix, the joints between the side parts forming the undercuts, and the other parts of the matrix adjacent to these side parts are preferably sealed.
A matrix is preferably used for the production of at least two package troughs. In addition to the bottom part, the side parts oriented transversely and the side parts oriented parallel to the direction of package trough feed, such a matrix has preferably at least one middle part which tapers preferably on both sides from the top of the matrix towards the bottom and is fixed in its spatial position in relation to the machine frame.
The side parts of such a matrix are also preferably formed in such a way that they can be used for the production of undercuts and are then also fixed in their spatial position in relation to the machine frame.
The middle parts and optionally the side parts which serve as a mold for an undercut are preferably interrupted by webs which do not taper downwards, so that no undercut is produced in the package trough at these points.
In another preferred embodiment, the middle parts and the side parts remaining unchanged in their spatial position in relation to the machine frame have a surface with a low coefficient of friction on their top. This surface can be either polished or coated with Teflon or a similar material.
In order to deep-draw the film with a vacuum into the matrix, the joints between the middle parts and optionally between the side parts forming the undercuts, and the other parts of the matrix adjacent to these side parts or middle parts are preferably sealed.
Another object of the present invention is to provide a process for the production of package troughs which does not have the disadvantages of prior art.
According to the invention, said object is achieved by Providing a process for the production of a package trough having at least one undercut, using the matrix according to the invention, wherein
the film from which the package trough is produced is fed over the matrix, optionally heated and formed into the matrix,
the vertically displaceable parts of the matrix are lowered, and
the finished package trough is moved on.
Heating of the film may also be effected upstream the deep drawing station.
In a preferred embodiment, the film is pressed with a die into the matrix and preformed therewith it and then finally formed using compressed air above the film and/or a vacuum beneath the film.
It is also preferred to deep-draw the film into the matrix using only compressed air above the film or only a vacuum beneath the film or a combination of pressure and vacuum.
The advantage of the present invention is that a package trough can be produced with one or more undercuts oriented parallel to the direction of package trough feed. By combining the features of the present invention with the features of the deep drawing station according to EP 0,538,570, it is even possible to provide the package trough with an additional undercut oriented transversely to the direction of package trough feed. The matrix according to the invention can be produced inexpensively, and the process according to the invention is easy to perform.
REFERENCES:
patent: 4372098 (1983-02-01), Mason
patent: 5014500 (1991-05-01), Robache
patent: 5241801 (1993-09-01), Nelson
patent: 5307610 (1994-05-01), Schneider et al.
patent: 5477660 (1995-12-01), Smith
patent: 690 03 880 T2 (1994-04-01), None
patent: 0 538 570 A1 (1993-04-01), None
patent: 2-45322 (1990-02-01), None
Blöcher Rolf
Inverardi Celestino
Thomas Ulrich
Akin Gump Strauss Hauer & Feld L.L.P.
Gerrity Stephen F.
Tawfik Sam
Tiromat Kramer & Grebe GmbH & Co. KG
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