The present invention relates to a method and an arrangement in a cardboard creasing machine performing creases on a cardboard blank web. The web has a width of at least two lanes of blanks in parallel to each other and comprise in at least one zone per pair of lanes an area where intentional creases on both are made transversally to a feeding direction of the machine. The crease-lines are on the male side interrupted to provide a longitudinal seal strip to an edge of each blank to become. The cardboard web is in a limited area of such an interruption intentionally and positively lifted and supported from the side of a female crease die to a level in between being in line with to being above an outermost surface of a female crease die roller of the machine. The present invention relates to a method and an arrangement in a cardboard creasing machine performing creases on a cardboard blank web (7). The web has a width of at least two lanes of blanks in parallel to each other and comprise in at least one zone per pair of lanes an area where intentional creases on both are made transversally to a feeding direction of the machine. The crease-lines are on the male side interrupted to provide a longitudinal seal strip to an edge of each blank to become. The cardboard web (7) is in a limited area of such an interruption intentionally and positively lifted and supported from the side of a female crease die to a level in between being in line with to being above n outermost surface of a female crease die roller of the machine.
The present invention relates to a method and an arrangement in cardboard creasing when performing creases on a cardboard web fed from a large roller, where said web comprise the width of at least two blanks in parallel to each other. More precisely the invention relates to measures taken in connection with creasing wear tools that normally cooperate in pairs in creating a certain crease pattern to lanes of coherent package blanks, made from cardboard.
Cardboard creasing is, as is well known in the art, made for facilitating folding of a material, which folding is to be performed after having made a pattern of crease lines thereon. Blanks for packages are sometimes like here prepared from wide webs comprising at least two blanks in parallel to each other. Within the packaging industry the term “blank” refers to a portion of a packaging material needed to form one package. A web comprises longitudinal lanes of blanks. The width of one lane equals the length or the width of one blank. When producing liquid food products containing for example water, these have to be contained in a more or less liquid proof package. For many years laminates comprising cardboard and polymer materials has been used for this purpose with an excellent result. When, however, producing cardboard packages of increased volumes, for instance such containing 1.5 liters or more, the stress on the material becomes larger and thus the thickness of the cardboard has to be increased.
As a result of the increased thickness there is a tendency of the cardboard material, while influenced by positively progressing male and female dies as well as different types of rollers in the feeding process thereof, which is positively progressing the cardboard material, to create what is called wild-creases. A wild-crease is an unwanted self-generated crease-like deformation or a defibration of a cardboard material between two adjacent intentionally made creases and seems to be the result of a necessary combination of high compression stresses to create the intentional creases, the mutual distance between the separated adjacent creases, the depth of each crease and the thickness of the creased material. This gives rise to shear stresses in the pulp layers of the cardboard material, which may cause delamination or defibration thereof, which in turn may produce the wild-creases. The wild-creases occur mainly between two coherent lanes in the modified offset printing process that constitutes the creasing process.
The wild-creases appears as an uncontrolled wrinkling of the cardboard in an area between two from one another independent co-linear male dies and more specifically between two separated crease lines, one on each blank. The crease lines can be realized by a crease-roller system well known to the skilled person and in such case the two separated crease lines are transversal to the tangential direction of any point of a crease plate in it's rotational direction. This is clearly shown in
In performing a scan regarding the state of the art regarding methods and/or arrangements dealing with the problem thus described, no relevant material was found.
A main object of the work that has resulted in the present invention has therefore been to provide a method and an arrangement that makes it possible to eliminate any risk of creation of wild creases, when it, due to factors such as required larger structural rigidity is required to make use of a thicker material for producing packages.
According to the invention this and other objects of the invention are achieved by the fact that the cardboard blank web (7) in a limited area of such an interruption is intentionally and positively elevated and supported from the side of a female crease die (in Z-direction=ZD) to a level coinciding with or above an outermost surface of the female crease die. Hereby the tensile stress of the material is released and no delamination or defibration will occur spontaneously.
In the following the invention will be described in more detail, having reference to a preferred embodiment thereof shown in the attached drawings, in which:
The technology representative to the present invention relates to a case where it is aimed to create unfolded package blanks from a large roller containing a preferably preprinted, cardboard web material of a width equaling at least the width of two package blanks.
According to
To provide a better understanding of how this is achieved,
Number | Date | Country | Kind |
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0500897-4 | Apr 2005 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE2006/000404 | 4/4/2006 | WO | 00 | 10/11/2007 |