EP2590814A1

EP2590814A1 - Die-cutting press and die-cutting method

Info

Publication number: EP2590814A1
Application number: EP10734726.2A
Authority: EP
Inventors: Attila TAKÁCS
Original assignee: SCA Packaging Hungary Kft
Current assignee: DS Smith Packaging Hungary Kft
Priority date: 2010-07-09
Filing date: 2010-07-09
Publication date: 2013-05-15
Anticipated expiration: 2030-07-09
Also published as: EP2590814B1; WO2012003879A1; PL2590814T3; HUE025107T2

Abstract

A die-cutting press (1) for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures (201) comprises a first and second die stamp (10, 20) movable toward each other to close the press (1), with the first die stamp (10) comprising a plurality of cutting knives (11S, 11L) protruding therefrom and arranged around at least a pressing and a holding surface (12, 13) on the first die stamp (10). The pressing surface(s) (12, 12') is/are arranged at different height (s) with respect to the holding surface(s) (13, 13'), and the amount of protrusion of a first set of the knives (HS) located between a pressing surface (12, 12') and a holding surface (13, 13') is less than that of a second set of the remaining knives (11L).

Description

Die-cutting press and die-cutting method

The present invention relates to a die-cutting press for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures, as well as to a corresponding die-cutting method.

Prior Art

In the packaging industry, buffer materials are generally used to protect packaged items from damage during transport and handling. A popular buffer material is for example polystyrene (in form of EPS panels or inserts) since such material has a very low density, therefore adding little weight to the package, and provides good shock resistance due to its large elastic modulus. Packaging inserts made of such material are often shaped to provide an item to be packaged in a cardboard box with a holding structure which holds it at a distance from the walls of the box and, by combining the shock absorbing properties of the insert material with room for motion in the box, protects it from damage when the box suffers impact during transport and handling.

One inherent problem in packaging boxes making use of polystyrene inserts is that the boxes' required structural rigidity can only be achieved by large volume foam inserts that provide a "frame* within the box and thus take up the linear and torsional forces that can act onto the outer cardboard box.

Polystyrene foam inserts have a further disadvantage in that they present ecological dangers because they cannot be recycled together with other plastics and are, therefore, often disposed of with residual waste which is ultimately destined to be deposited in a landfill or incinerated. To avoid these problems and provide the users of the package or box (both manufacturers and consumers) with a more

appealing disposal option, the use of paper-based inserts has developed, and particularly the use of so-called honeycomb boards in which honeycomb-like cells of paper are provided on face sheets of cardboard, such as corrugated cardboard, or are sandwiched between two such face sheets. Due to the honeycomb-like structure, the resulting honeycomb board provides outstanding rigidity and torsional stability. In the above and throughout the present application, when the term "honeycomb" or "honeycomb-like" is used, it is to be

understood that this shall not limit the structure to an actually honeycomb-shaped cell structure, i.e. is to an essentially hexagonal cell shape, but that equivalent cell structures, such as those made up of wave-like shifted cell walls, are also comprised in the present definition of the term.

One of the developments of this technology are packaging solutions in which the structural rigidity of an outer cardboard box is achieved by reinforcing only the edges and corners of the box with the above mentioned honeycomb paper structures. However, these rigid honeycomb structures cannot provide the desired resilience in order to cushion the packaged item and absorb shocks onto the item that may occur during handling of the package.

To overcome this problem, US patents 2,728,479 and 2,761,553 teach to at least partially compress honeycomb panels and, thus, partially or totally crush their honeycomb structure so as to transform the core of the panel into bellows-like cells as cushioning layers, for use as inserts in box-shaped packages. Due to the way of compressing the panels, i.e. in parallel to the cells' honeycomb-like walls, the direction of cushioning is also parallel to these walls, and perpendicular to the face sheet of the panel. In use, the partially crushed layer of the honeycomb material is adjacent to the item to be packaged while the uncrushed portion, via the face sheet, forms the outer wall of the package. However, due to the partial crushing of the cells, the inserts provide only insufficient structural rigidity. A unsatisfactory approach to solve this issue is to increase the overall thickness of the insert, which however renders it less practical and more expensive to produce.

To pack fragile items, in particular, solutions have been proposed in which both uncompressed honeycomb inserts and compressed honeycomb inserts are placed together in a

package, so that the provision of rigidity and of cushioning are structurally divided, the uncompressed honeycomb insert being optimizes for rigidity, and the compressed one for cushioning. Such use of honeycomb material is, for example, disclosed in WO 98/42589 A1.

However, such packages as in WO 98/42589 Al are used to package fragile items of relatively small weight, such as crockery, vases or statuettes, i.e. having a weight below about 5 kg. For larger items, in particular fragile or shock- sensitive objects such as flat LCD TV sets, corrugated boxes with EPS buffers are widely used. This type of packaging, however, brings about logistical problems because combining corrugated boxes with EPS buffers for flat LCD TV packaging in normal circumstances means that the stacking strength is something to be provided by the corrugated box. Due to thinner and thinner TV sets the industry is struggling with production of boxes with appropriate strength at reasonable prices. Anyway, appropriately strong standing type boxes are too thin and need support in order not to tip over during transport and handling, while horizontal orientation boxes are too difficult to use from a packing and unpacking point of view.

Therefore, it is desirable to combine compressed and

uncompressed elements to give not only cushioning , but to achieve outstanding stacking strength and torsional rigidity, too. Thus, as this type of construction offers the most flexibility in arranging structurally rigid parts, for example at corners and edges, and cushioning parts, for example on the side panels and behind the rigid uncrushed honeycomb frame, the desire has arisen to provide a

production method for a honeycomb insert that allows both the use of only a small number of inserts for providing the desired rigidity, cushioning and stacking strength, and is easy and cheap to produce, in particular in view of changing shape specifications which many commercially valuable fragile items like flat panel TVs are subject to.

Document WO 98/12045 discloses an apparatus and method for crushing a honeycomb board in which rollers progressively compress the honeycomb board along predetermined regions of the board so as to create compressed areas. However, it is difficult to control the final height in the compressed area of the honeycomb board, in particular at the transitions between compressed and uncompressed regions. Moreover, it is virtually impossible to create compressed regions of

different width, or in general of different geometries. Only by a further cutting step it is possible to provide inserts of at least custom-shaped overall size to be included in a package or box.

Document EP 0 705 165 discloses a method in which a honeycomb paper board is compressed and cut to individual rectangular pieces in the same method step. However, this method is only able to provide a crushed-cell insert, so that the provision of both structurally rigid inserts and cushioning inserts requires separate manufacturing devices and steps. Moreover, there remains the need for insert shapes and forms that can be easily and well adapted to the various objects to be packaged.

Summary of the invention In view of the above, it is an object of the present

invention to provide a die-cutting press and a die-cutting method which are able to produce, in a single process, both a structurally rigid and resilient honeycomb paper insert of predetermined shape that can be directly used in packaging boxes to provide both mentioned effects, minimising the number of components necessary to set up a complete box and therefore saving material, time and costs. This object is achieved by means of a die-cutting press as claimed in claim 1 and by a die-cutting method as claimed in claim 12.

Preferred embodiments of the invention are defined in the respective dependent claims.

According to the invention, a die-cutting press for cutting and forming one or more dual-purpose compressed and

uncompressed honeycomb paper structures comprises a first and second die stamp movable toward each other to close the press, with the first die stamp comprising a plurality of cutting knives protruding therefrom and arranged around at least a pressing and a holding surface on the first die stamp. The pressing surface (s) is/are arranged at different height (s) with respect to the holding surface (s), and the amount of protrusion of a first set of the knives located between a pressing and a holding surface is lees than that of a second set of the remaining knives.

The honeycomb paper structures comprise a core made of a plurality of hollow cells defined by cell walls, in which the hollow cells define opposing planar sides which are

substantially perpendicular to the cell walls and at least one of which, but preferably both, is/are covered by a face sheet. The term "uncompressed" refers to such a honeycomb paper structure in which the cells have not been crushed by application of a force parallel to the cell walls, whereas the term "compressed" refers to such portions of the

honeycomb paper structures in which the cell walls have been at least partially deformed along at least a portion of the cell walls' height, and thus in this area portion no longer provide the rigidity and stiffness of the uncompressed cell walls, but rather resilience and cushioning in a direction substantially perpendicular to the planar sides of the honeycomb paper structure (substantially parallel to the direction of the cell walls in an uncompressed state) .

As used above, dual-purpose honeycomb paper structures thus provide both the rigidity necessary to reinforce a packaging box, for example along edges and/or corners, and the

resilience required for cushioning fragile or sensitive items held by the inserts within the package. The one or more inserts manufactured with the above die-cutting press provide both benefits at the same time, while being available in predetermined shapes and numbers in mass production.

It is to be particularly observed that by virtue of the presence of the pressing surfaces and the holding surfaces that are arranged at different heights, and the two sets of knives with a different amount of protrusion, it is possible to create honeycomb paper structures with compressed and uncompressed area portions next to each other (in the plane of the sides or the face sheet) , the thicknesses of which are precisely defined and which can, therefore, be tailored to the specific requirements of packaging fragile or sensitive items, such as for example flat panel TVs. As stated, the pressing surface (s) is/are arranged at different height (s) with respect to the holding surface (s) , in other words these two types of surfaces have a different degree of protrusion from a common imaginary base plane (which may, for example, be a base plate of the first die stamp) , and therefore can compress (in the case of pressing surfaces) or simply hold (in the case of holding surfaces) the respective portions of the honeycomb paper structure sandwiched between the first die stamp and the second die stamp, when the press is closed. One may note that while the pressing surface imparts a deforming pressure onto the honeycomb paper structure inserted between the first and the second die stamp, also the holding surface may exert a certain non-deforming amount of pressure, which is not sufficient to permanently deform the cells of the honeycomb paper structure. The pressure exerted by the holding surface (s) shall merely be sufficient to contact and hold area portions of the honeycomb paper structure so that they do not move inadvertently during the process and can be cut to a predetermined shape.

It is also to be understood that the exact height or position of the pressing surfaces and holding surfaces, as well as the amount of protrusion of the first set and of the second set of knives will, in general, depend on the desired thickness of the dual-purpose honeycomb paper structures which are to be produced. However, by having the second set of knives protruding more than the first set of knives, it is possible to completely cut individual pieces out of the inserted honeycomb paper structure blanks and at the same time provide partial cuts on these pieces which do not completely

penetrate through the entire thickness of the honeycomb paper structure, therefore leaving the core of the honeycomb paper structures intact when passing from an uncompressed area portion (that was contacted and held by the holding surface) to a compressed area portion (pressed upon by a pressing surface) .

The die-cutting press according to the invention is thus able to produce, directly from honeycomb paper structure precursor or blank, ready-to-use dual-purpose compressed and

uncompressed honeycomb paper structures, such as individual pieces or inserts that are provided both with an uncompressed area portion and a compressed area portion, for immediate use in reinforcing and cushioning within packaging boxes. It is no longer necessary to separately and sequentially process a blank of honeycomb material, but the blank can be processed in a single operation by the die-cutting press of the invention to produce the immediately usable insert.

It is of course possible to arrange the first die stamp to be either the upper die stamp or the lower die stamp, in other words the die-cutting press is able to work both from above or from below, only the relative movement between the die stamps is necessary.

In a preferred embodiment, the first die stamp comprises at least one ejector element associated with each pressing and holding surface to eject the honeycomb paper structures therefrom. By means of the ejector element, it is possible to compress and cut even honeycomb material having thicknesses up to 200 mm, which otherwise would remain stuck in the first die stamp. Since each pressing and holding surface has an associated ejector element, all cut and formed dual-purpose honeycomb paper structures or pieces can be pushed out of the first die stamp and removed from the stamp bed for the insertion of a new honeycomb blank. At the same time, being able to push out and remove the finished pieces is achieved without any restriction to the form or shape of the finished piece .

It is further preferred that the pressing and/or holding areas are fastened to the first die stamp by the ejector elements. By fastening the pressing and/or holding areas by means of the ejector elements, separate holding structures for ejector elements and pressing and holding areas are avoided. Moreover, due to their connection it becomes possible to have the pressing and/or holding areas

collaborate with the ejector elements.

Advantageously, the ejector elements are resilient elements that are capable to be tensioned when the die-cutting press is closed and to rebound when the die-cutting press is opened. By virtue of the above described association, it is possible to devise a very simple structure capable of pushing out the finished individual pieces or inserts by exploiting the energy stored in the ejector elements when the die- cutting press is closed and the pressing and/or holding surfaces move towards the areas to be compressed/to remain uncompressed. This is an important simplification in terms of structure as it avoids separate tensioning members for the ejector elements which would increase the size of the die- cutting press and increase its costs, both from a

manufacturing and from an operating point of view.

In an advantageous configuration of the die-cutting press, it is also envisioned that the ejector elements are pressurized air nozzles. In this configurat on, the ejection is performed by pressurised air, and thus the inserts or pieces are treated very gently when pushing them out of the first die stamp, as there needs to be no contact between the ejector elements and the honeycomb paper piece.

Alternatively, the ejector elements may be springs or resilient material. This configuration is mechanically simpler and avoids the possibly higher operating and

maintenance costs of air nozzles. Moreover, springs are preferred for very thick honeycomb paper material (of the order of 20 to 200 mm thickness) , where large forces will occur upon pressing and cutting that need to be borne by the ejector elements associated and fastened thereto, whereas resilient material such as (technical) rubber or resilient plastic foams are suitable for thin honeycomb paper material in the range up to about 20 millimetres thickness.

In a further advantageous modification of the die-cutting press, the knives comprise a serrated edge. By providing a serrated edge, it is possible to more cleanly cut both the face sheet cardboard of the honeycomb paper structure and the cell walls of the honeycomb-like cells. In the die-cutting press of the invention, the second die stamp may advantageously comprise a flat surface having recesses adapted to receive the second set of knives when the die-cutting press is closed. By virtue of the recesses, it is possible to obtain a particularly clean through-cut which is effected by the second set of knives, since these knives may completely pass through the honeycomb paper structure and be received in the recesses. Further, these recesses also serve to protect the blades of the second set of knives from being worn too quickly, a problem arising for instance when they are pressed onto a flat surface of a die stamp. Consequently, the recesses will be appropriately sized, so that the second set of knives will not touch the bottom of the recesses when the die-cutting press is closed.

It is particularly advantageous if the perimeter of the pressing and/or holding surfaces comprises a curved or angled line, wherein the angled line comprises at least one not substantially right angle. In other words, the outer edge of the dual-purpose compressed and uncompressed honeycomb paper structures and/or the borderline between uncompressed and compressed area portions may be of these line shapes, and thus perfectly adaptable to the intended use. This is

particularly advantageous in packaging of shock-sensitive electronic equipment, since these items mostly require non- straight peripheries of the insert and the compressed and uncompressed area portions.

Preferably, the die-cutting press of the invention further comprises first blocker elements arranged between the holding surface (s) and the first die stamp so as to provide a minimum distance between the holding surface (s) and the second die stamp when the press is closed. The blocker elements thus prevent the holding surfaces from coming too close to the second die and risk compressing the honeycomb paper structure in areas that should remain uncompressed. It is also preferred that the die-cutting press of the invention further comprises second blocker elements of different selectable thicknesses arranged between the pressing surface (s) and the first die stamp so as to provide the different heights of the pressing surface (s) with respect to the holding surface (s) . By employing the second blocker elements, it is possible to obtain different grades of compression of the honeycomb paper structures, and therefore different physical heights or thicknesses in the finished product .

In a second aspect, the invention provides a die-cutting method for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures by means of the above die-cutting press, comprising the steps of: a) providing a honeycomb paper board (blank) between the opposed die stamps, the honeycomb paper board having a core made of a plurality of hollow cells defined by cell walls, the hollow cells defining opposing planar sides which are substantially perpendicular to the cell walls and at least one of which is covered by a face sheet, b) moving the die stamps towards each other so as to

- partially cut the honeycomb paper board in a thickness direction thereof by means of the first set of knives along one or more first cutting lines,

- completely cut through the honeycomb paper board in the thickness direction thereof by means of the second set of knives along one or more second cutting line(s) to form one or more separate honeycomb paper structures (pieces) , each defined by the second cutting line(s) and having distinct area portions defined by the first cutting line(s),

- substantially simultaneously contact one or more distinct area portions in correspondence with the holding surface (s) to form one or more uncompressed area portions of a given thickness that provide (s) structural stiffness and rigidity, and - substantially simultaneously press upon one or more distinct area portions by means of the pressing surface (s) to form one or more compressed area portions of one or more smaller thicknesses that provide (s) resilience and

cushioning.

The honeycomb paper board provided between the opposed die stamps will generally be a (pre-cut) honeycomb paper board serving as blank for the production of the dual-purpose compressed and uncompressed honeycomb paper structures (for example inserts for packaging boxes) .

When moving the die stamps toward each other, this relative motion may be either achieved by moving the first die stamp or the second die stamp or both, where either of the die stamps may be arranged as an "upper* die stamp and the other as the lower die stamp, according to requirements. Further, the die stamps may also be arranged differently, such as vertically, as long as they are movable toward and away from each other to respectively open and close the die stamp.

Partially cutting the honeycomb paper board here means that the honeycomb paper board is not completely cut through its thickness but rather cut only up to a certain depth smaller than the board thickness, so that at least a part of the honeycomb paper board will remain continuous across the cut. Conversely, the complete cutting through the honeycomb paper board will severe the honeycomb paper board portions on either side of the one or more second cutting lines. Thus, each separate honeycomb paper structure or piece will comprise, as mentioned, at least an uncompressed area portion and a compressed area portion, the separate pieces being surrounded by their outer contour or perimeter formed by completely cutting through the honeycomb paper board. The mentioned uncompressed area portion (s) is/are provided by merely contacting it/them with the holding surface (s) which does/do not exert a pressure leading to the crushing of the honeycomb core of the structure. Simultaneously, the

compressed area portion (s) is/are obtained by the pressure exerted by the pressing surface (s) , with their divisional line (first cutting line) between the compressed area portion and the uncompressed area portion being provided by the partial cutting of the shorter knives belonging to the first set of knives. Thus, the first set of knives does not cut through all the material and may save part of the cell structure or at least the face sheet .

Advantageously, the method further comprises step c) of moving the die stamps apart to open the die-cutting press and release the one or more separate, cut and formed honeycomb paper board structures, and step d) of removing said

structures from the die stamp. The removal may, preferably, be effected by moving forward a plank on which the cut and formed honeycomb paper board structures remain when the die stamps are opened. After that, the next die cutting operation can begin.

In a preferred embodiment, step c) includes ejecting the honeycomb paper board structures by the ejector elements that mechanically or pneumatically push them out of the die stamp. In this manner, it is possible to make sure that the cut and formed honeycomb paper board structures do not get stuck in the first die stamp, and that they remain on the second die stamp or, preferably, on the movable plank. Further, this step allows to efficiently remove even very thick honeycomb paper structures, for example having thicknesses up to 200 mm, from the die stamps without damaging them and, thus, maintaining their usefulness as ready-to-use structures.

Preferably, step b) includes biasing or tensioning the ejector elements prior to pressing upon the one or more distinct area portions by means of the pressing surfaces. It is thus possible to further simplify the operation of the die-cutting press in that the step of pressing also charges, biases or tensions the ejector elements without requiring a separate step or structure to that end. Consequently, cost efficiency and time savings are improved.

It is particularly advantageous if the first and/or second cutting lines comprise a curved or angled line, wherein the angled line comprises at least one not substantially right angle. In this way, it is possibly to perfectly adapt the outer edge of the honeycomb paper structures and/or the borderline between uncompressed and compressed area portions to the intended use. This is particularly advantageous in packaging of shock-sensitive electronic equipment, since these items mostly require non-straight peripheries of the insert and the compressed and uncompressed area portions.

Brief description of drawings

In the following, the invention will be described by means of an exemplary embodiment depicted in the appended drawings, in which

Figure 1 is a plan view of the first die stamp of the die- cutting press of the invention;

Figure 2 is a sectional view along the line A-A in Figure 1;

Figure 3 is a partial perspective view of a detail of a pressing surface of the first die stamp in the die-cutting press of the invention; and

Figure 4 is a perspective view of an ejector element by which the pressing and/holding areas are fastened to the first die stam .

Detailed description Figure 1 shows a plan view of the active surface of an upper die stamp (first die stamp) 10 according to one embodiment of the invention, which comprises pressing surfaces 12, 12', holding surfaces 13, 13', and scrap holding surfaces 14.

These surfaces are separated by gape 16a, b, c and 17a, b, c (17 a', b' , C) in which a plurality of cutting knives 11L, 11S are arranged around the pressing surfaces 12 (12') and the holding surfaces 13 (13'). The knives that are arranged in gaps 17a, b, c (17a' , b' , c' ) separating the pressing surface 12 and the holding surface 13 (12', 13') belong to a first set of knives 11S, while the remaining knives belong to a second set of knives 11L. It is noted that the die-stamp of the present example is designed to produce two separate but substantially identical honeycomb paper structures from one blank, which are respectively formed by pressing and holding surfaces 12, 13 and pressing and holding surfaces 12', 13' . Therefore, knives belonging to the second set 11L are

arranged in gap 16c that extends between pressing surface 12 and holding surface 13', as well as between pressing surface 12' and holding surface 13. The knives of this set are also provided between pressing or holding surfaces 12, 12'; 13, 13' and scrap holding surfaces 14.

As can be seen from Figure 2, the first set of knives lis has an amount of protrusion from the first die stamp 10 (from the base plate 15 of the first die stamp) which is less than the amount of protrusion of the second set of knives 11L. The longer knives 11L of the second set are dimensioned to cut through the entire thickness of a honeycomb paper board 200 to be placed upon the lower die stamp 20, while the shorter knives lis of the first set are dimensioned to cut only partially through the thickness of the honeycomb paper board 200.

The pressing and holding surfaces 12, 13 (12', 13') as well as the scrap holding surfaces 14 are fastened to the base 15 of the first die stamp 10 by means of springs (ejector elements) 30, which in an untensioned state resiliently hold them at a distance from the base 15 of the first die stamp 10. As can be seen by reference to Figures 2 and 4, the spring 30 passes through an appropriate bore 33 formed through the base 15 of the first die stamp and is fixed to the base 15 of the first die stamp 10 at its other side (away from the pressing and holding surfaces) by means of a screw 32 that passes through a lateral spring eyelet 30a at the upper end of the spring 30. At the other, lower end the spring is fixed to the pressing, holding or scrap surfaces 12, 13, 14 (12', 13', 14') by means of a screw 31 passing through a central eyelet 30b of the spring 30 and

collaborating with a nut 34 provided in the pressing, holding and scrap surfaces.

To set the minimum distance between the holding surface and the second die stamp when the press 1 is closed, and thus to hold the honeycomb paper board 200 without compressing it (thereby forming uncompressed area portions 220) , first blocker elements 41 are fixed to the base 15 of the first die stamp 10 so as to be arranged between the base 15 and the holding surfaces 13 , 13 ' .

Between the pressing surfaces 12, 12' and the base 15 of the first die stamp, auxiliary pressing surfaces 16 are arranged which are distanced from the pressing surfaces 12, 12' by second blocker elements 42 of different selectable

thicknesses. These second blocker elements 42 are fixed both to the pressing surfaces 12, 12' and the auxiliary surface 16 by means of pins 42a that are press-fitted into appropriately shaped holes 43 of the pressing surface 12 and the auxiliary surface 16. The fitting is such that the second blocker element can be removed and exchanged for another one of different thickness, but affording sufficient holding force when inserted so as to avoid a disconnection of the pressing surface 12 from the auxiliary surface 16. As can further be seen form Figure 2, the second die stamp 20 has a flat surface 21 in which recesses 22 are formed that are shaped and adapted to receive the longer knives 11L of the second set when the die-cutting press has been completely closed. In this manner, a cleaner cut is achieved and pieces still hanging together at the end of the cutting and forming operation are avoided.

It is to be understood that while in the present description the term "surface* is used to describe the pressing, holding, scrap holding and auxiliary surface, the actual surfaces are provided on plates, but the actions of pressing and holding, respectively, are of course effected by the surfaces thereof. Thus, in the present description, a bore through the surface is to be understood as a bore through the corresponding plate.

Next, the die-cutting method for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures will be described. The following description will illustrate the method of the invention by means of the die- cutting press 1 discussed above, however variations and modifications from such press are possible so long as they have no influence onto the substantial steps of the inventive method.

First, a honeycomb paper board 200, which comprises a core made of a plurality of cells 210 is provided between the opposed first and second die stamps 10, 20. The cells are formed by cell walls 211 which extend between and

perpendicular to an upper face sheet 214 and a lower face sheet 215 which define opposing planar sides of the board 200. It is to be understood that the term honeycomb refers not only to strictly hexagonal-shaped cells but also to square cells, diamond-shaped cells or other cell geometries that provide the same structural rigidity and torsional stiffness as the strictly honeycomb- (hexagonal-) shaped cells. After placing the honeycomb paper board 200 onto the second die stamp 20, the die stamps 10, 20 are moved towards each other, and the pressing surfaces 12, 12' and holding surfaces 13, 13' begin to contact the upper face sheet 214 of the board 200 (see movement according to arrow I in Figure 2) . Moving the stamps together compresses the springs 30

associated with the holding surfaces 13, the pressing

surfaces 12 and the scrap surfaces 14, without however compressing the board 200. In this way, energy is stored in the springs 30.

Moving the board further down now starts to compress distinct area portions of the board 200 by means of the pressing surfaces 12, since these are now engaged with the base 15 of the first die stamp 10 via the second blocker element 42, the auxiliary surface 16 and the blocker elements 41' . The compression at least partially crushes the cells of the honeycomb paper board 200 in correspondence to the pressing surfaces. At the same time, the knives 11L and lis cut through the honeycomb paper board 200 in a vertical

direction. This compressing and cutting movement is

schematically indicated by arrow II in Figure 2.

Substantially simultaneously thereto, the holding surfaces 13 contact distinct area portions of the board 200, however without compressing or crushing their core, although a small amount of pressure may be exerted by the holding surfaces 13 onto the upper side (upper face sheet 214) of the honeycomb paper board 200.

During this movement II, the knives 11L completely cut through the honeycomb paper board 200 in the thickness direction thereof along cutting lines corresponding to the gaps 16a, b, c, which separates individual honeycomb paper structures 201 from the paper board 200. At the same time, the knives 11S of the second eet cut partially through the thickness of the board 200 in correspondence with first cutting lines (along gape 17a, b, c; 17a', b' , c') so that the individual separate honeycomb paper structures 201 form uncompressed area portions 220 of a thickness corresponding to that of the initial honeycomb paper board 200, and compressed area portion 230 of a smaller thickness, in which the underlying honeycomb cells have been at least partially compressed/crushed. The uncompressed and compressed area portions 220, 230 are neatly distinct by the cutting action of the set of knives lis, which have cut through the

honeycomb paper board 200 only down to a thickness

corresponding essentially to the difference of the thickness of the uncompressed and the compressed area portions.

Moreover, this die-cutting method produces, in correspondence to the scrap surfaces 14, scrap pieces 202 which have been correspondingly severed from the surrounded individual honeycomb paper structures 201 by cutting knives 11L, and which are discarded after cutting.

Next, the die stamps 10, 20 are moved apart again to open the die-cutting press 1. In doing so, the tensioned springs 30 start to release their energy and push the individual honeycomb structures 201 and scrap pieces 202 out of the first die stamp 10. In this manner, it is avoided that they get stuck between the surrounding knives 11L, lis, and the cut and formed honeycomb paper board structures are deposited onto the second die stamp 20, from which they may be removed by means of a movable plank (not shown) .

By the method described above, it is possible to produce honeycomb paper structures which comprise both compressed and uncompressed area portions, and which are, therefore, immediately usable as inserts for packaging purposes, providing both structural rigidity and torsional stiffness by means of their uncompressed area portions, for example in correspondence to the corners and edges of a packaging box, and resilience and cushioning by the compressed area portions, onto which items or objects sensitive to mechanical shock (like flat panel TV sets) can be placed. Thus,

according to the method of the invention it is possible to provide inserts for a packaging box in a single die-cutting operation, while saving material, time and costs.

It is to be understood that in the above description, an exemplary embodiment of the inventive method has been

described and that modifications to this method may be performed without departing from the scope of the appended claims. For example, the relative distances and dimensions, which were only schematically indicated in Figure 2, can be chosen according to the specific requirements of the

application such as board thickness, relative height of compressed and uncompressed area portions, degree of

compression, etc.

The die-cutting press 1 of the invention may further have different geometries and arrangements of the holding, pressing and scrap surfaces, according to the specific shapes of the honeycomb paper structures to be produced. It is particularly observed that the die-cutting press and method of the invention are capable of producing honeycomb paper structures of custom shapes and sizes having perimeters that may comprise not only straight lines but also angled lines and/or curved lines, wherein the angled line may comprise at least one not substantially right angle.

Claims

1. A die-cutting press (1) for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures (201) , comprising a first and second die stamp (10, 20) movable toward each other to close the press (1), with the first die stamp (10) comprising a plurality of cutting knives (lis, 11L) protruding therefrom and arranged around at least a pressing and a holding surface (12, 13) on the first die stamp (10) ,

characterized in that

the pressing surface (s) (12, 12') is/are arranged at different height (s) with respect to the holding surface (s) (13, 13'), and that the amount of protrusion of a first set of the knives (11S) located between a pressing surface (12, 12') and a holding surface (13, 13') is less than that of a second set of the remaining knives (11L) .

2. The die-cutting press (1) of claim 1, wherein the first die stamp (10) comprises at least one ejector element (30) associated with each pressing and holding surface (12, 13) to eject the honeycomb paper structures (201) therefrom.

3. The die-cutting press (1) of claim 2, wherein the pressing and/or holding surfaces (12, 13) are fastened to the first die stamp (10) by the ejector elements (30) .

4. The die-cutting press (1) of claim 2 or 3, wherein the ejector elements (30) are resilient elements that are capable to be tensioned when the die-cutting press (1) is closed and to rebound when the die-cutting press (1) is opened.

5. The die-cutting press (1) of claim 2, wherein the ejector elements are pressurized air nozzles.

6. The die-cutting press (1) of any of claims 2 to 4, wherein the ejector elements are springs (30) or resilient foamed material.

7. The die-cutting press (1) of any of the preceding claims, wherein the knives (11S, 11L) comprise a serrated edge.

8. The die-cutting press (1) of any of the preceding claims, wherein the first set of knives (IIS) comprises two sub-sets of knives with mutually different amounts of

protrusion.

9. The die-cutting press (1) of any of the preceding claims, wherein the second die stamp (20) comprises a flat surface (21) having recesses (22) adapted to receive the second set of knives (11L) when the die-cutting press (1) is closed.

10. The die-cutting press (1) of any of the preceding claims, wherein the perimeter of the pressing and/or holding surfaces comprises a curved or angled line, wherein the angled line comprises at least one not substantially right angle.

11. The die-cutting press (1) of any of the preceding claims, further comprising first blocker elements (41, 41') arranged between the pressing and holding surface (s) (12, 13) and the first die stamp (10) so as to provide a minimum distance between these surface (s) and the second die stamp (20) when the press (1) is closed.

12. The die-cutting press (1) of any of the preceding claims, further comprising second blocker elements (42) of different selectable thicknesses arranged between the

pressing surface(s) (12, 12') and the first die stamp (10) so as to provide the different heights of the pressing

surface (s) with respect to the holding surface (e) (13, 13').

13. A die-cutting method for cutting and forming one or more dual-purpose compressed and uncompressed honeycomb paper structures (201) by means of a die-cutting press (1)

according to any of the preceding claims, comprising the steps of:

a) providing a honeycomb paper board (200) between the opposed die stamps (10, 20) , the honeycomb paper board having a core made of a plurality of hollow cells (210) defined by cell walls (211) , the hollow cells defining opposing planar sides which are substantially perpendicular to the cell walls and at least one of which is covered by a face sheet (14, 15),

b) moving the die stamps (10, 20) towards each other so as to

- partially cut the honeycomb paper board (200) in a thickness direction thereof by means of the first set of knives (11S) along one or more first cutting lines (17a, b, c; 17a', b' , C) and

- completely cut through the honeycomb paper board (200) in the thickness direction thereof by means of the second set of knives (11L) along one or more second cutting line(s) (16a, b) to form one or more separate honeycomb paper structures (201) , each defined by the second cutting line(s) and having distinct area portions (220, 230) defined by the first cutting line(s), and

- substantially simultaneously contact one or more distinct area portions in correspondence with the holding surface (s) (13, 13') to form one or more

uncompressed area portions (220) of a given thickness that provide (s) structural stiffness and rigidity, and

- substantially simultaneously press upon one or more distinct area portions by means of the pressing surfaces (12, 12') to form one or more compressed area portions (230) of one or more smaller thicknesses that provide (s) resilience and cushioning.

14. The method of claim 12 or 13, further comprising step c) of moving the die stamps (10, 20) apart to open the die- cutting press (1) and release the one or more separate, cut and formed honeycomb paper board structures (201) , and step d) of removing said structures from the first die stamp (10) .

15. The method of any of claims 12 to 14, wherein step c) includes ejecting the honeycomb paper board structures (201) by the ejector elements (30) that mechanically or

pneumatically push them out of the first die stamp (10) .

16. The method of claim 15, wherein step b) includes biasing or tensioning the ejector elements (30) prior to pressing upon the one or more distinct area portions (220, 230) by means of the pressing surfaces (13, 13').

17. The method of any of claims 12 to 16, wherein the first and/or second cutting lines (17a-c, 17a' -c' 16a, b) comprise a curved or angled line, wherein the angled line comprises at least one not substantially right angle.