WO2015173671A1

WO2015173671A1 - A weakening device and method for realizing a weakening line in packaging sheets

Info

Publication number: WO2015173671A1
Application number: PCT/IB2015/052576
Authority: WO
Inventors: Andrea Toro
Original assignee: System S.P.A.
Priority date: 2014-05-16
Filing date: 2015-04-09
Publication date: 2015-11-19

Abstract

A weakening device (8) comprises at least a rest plane (12) having a slot (13) and suitable for receiving a packaging sheet (3). The slot (13) extends along a line of longitudinal extension (L) lying in said rest plane (12). A pressing member (14) extends over a length (I) parallel to the line of longitudinal extension (L) and is suitable for obtaining a crease (9a) parallel to the line of longitudinal extension (L). Activating means (22, 23) are operationally connected to the pressing member (14) and are suitable for generating a working stroke (19) of the pressing member (14) in a plane perpendicular to the rest plane (12) and containing the line of longitudinal extension (L). At least one set of cutting members (26a, 26b, 34, 35) arranged at least at one end of the slot (13) and configured for realizing at least an opening (9b). The cutting members comprise first cutting portions (26a, 26b, 34) movable through the slot (13) along a cutting stroke (25). Connecting means (15a, 15b; 15) are operatively interposed between the pressing member (14) and the cutting members, and are configured to make the first cutting portions integral with the pressing member (14) during the working stroke (19) so as to generate the cutting stroke (25).

Description

A Weakening Device and Method for Realizing a Weakening Line in

Packaging Sheets

DESCRIPTION

The present invention relates to a weakening device and method suitable for realizing a weakening line in packaging sheets for realizing blanks for packages of articles.

It is known to manufacture packages of articles, for example, made-to- measure packages of articles, by folding one or more blanks suitably realized along a folding line. The folding of the blank has the aim to realize two package walls (e.g., a box), incident on the folding line.

It is known to realize a weakening line on the packaging sheet wherefrom the blank is obtained relative to the folding line so as to facilitate both manual and automatic folding operation. The weakening line typically includes a crease crossing through the packaging sheet and two openings of the said crease.

With reference to the present invention, with the term crease it is meant a pre-folding line obtained for example via a pressing or impression method to be applied on packaging sheets so as to facilitate the folding thereof, thus preventing deformation and cracking.

In the weakening line, the crease joins the two openings at the end thereof and facing outwards the packaging sheet.

At present these two processing, namely the creasing and the realization of the two end openings thereof, are performed in two different moments and in two separate stations, thus requiring rather long processing times as well as duplication of several devices within the packaging production plant.

in this context, the technical task of the present invention is to afford a weakening device and method so as to obviate the drawbacks of the prior art mentioned above.

In particular, it is an object of the present invention to provide a weakening method able to reduce the processing times if compared to traditional packaging systems,

A further object of the present invention is to provide a weakening device structurally simplified therefore not involving the presence of redundant devices.

The technical task and the aims as mentioned are substantially attained by a weakening device comprising the technical features in accordance with one or more of the appended claims. The dependent claims correspond to different embodiments of the invention.

In accordance with a first aspect, the present invention relates to a weakening device suitable for realizing a weakening line in packaging sheets for realizing blanks for packages of articles. Such weakening device comprises at least one rest plane adapted to receive a packaging sheet. Said rest plane comprises at least one slot extending along a iine of longitudinal extension lying in the rest plane. The weakening device further comprises a pressing member extending over a length parallel to the line of longitudinal extension and suitable for realizing a crease parallel to the line of longitudinal extension.

Activating means are operationally connected to the pressing member and suitable for generating a working stroke of said pressing member preferably in a plane perpendicular to the rest plane and containing the line of longitudinal extension. The working stroke is perpendicular to the line of longitudinal extension and develops between a resting position and a pressing position, wherein the pressing member is predisposed for realizing the crease.

Cutting members are arranged relative to at least one end of the slot and configured for fashioning at least one opening at the end of the crease, said opening being defined by two longitudinal cutting lines and one transversal cutting line. The cutting members comprise first cutting portions which are movable through the slot along a cutting stroke.

Connecting means are operationally interposed between the pressing member and the cutting members, and are configured for making the first portions integral with the pressing member during the working stroke so as to generate the cutting stroke.

in accordance with a second aspect, the present invention relates to a machine for realizing blanks for packages of made-to-measure articles, comprising feeding means for feeding packaging sheets, custom-made cutting means of packaging sheets and at least one weakening device. In accordance with a further aspect, the present invention relates to a weakening method able to realize a weakening line of packaging sheets for realizing blanks for packages of articles. According to said procedure there is provided to prepare a packaging sheet on a rest plane comprising at least one slot extending along a line of longitudinal extension lying in the rest plane; it is further provided to obtain a crease parallel to the line of longitudinal extension of the packaging sheet by moving a pressing member along a working stroke, as well as to realize at least an opening at the end of the crease, said opening being defined by two longitudinal cutting lines and one transversal cutting line being movable trough the slot along a cutting stroke of the first cutting portions of the cutting members. The first cutting portions are integral with the pressing member during the working stroke so as to generate the cutting stroke.

According to the aspects proposed, the present invention allows to realize both the crease and the opening/s at the and thereof in a single passage, thereby simplifying the structure of the plant also reducing production times.

In one or more of the aspects indicated, one or more of the following characteristics can be provided.

A single slot crossing through the rest plane along the line of longitudinal extension is preferably provided. Alternatively, two end slots can be made available which are connected for example by a groove, suitable for enabling realization of the crease.

Preferably the activating means are suitable for generating a return stroke of the pressing member between a pressing position and a resting position. The activating means are particularly configured for making the first cutting portions integral with the pressing member during the return stroke.

Preferably, the working stroke and/or the return stroke lie in a vertical plane so that the resting position of the pressing member is a raised position, wherein said pressing member keeps a distance from the rest plane and therefore from the packaging sheet; conversely, the pressing position is a lowered position, in which the pressing member comes into contact with the packaging sheet lying on the rest plane, pressing it relative to the line of longitudinal extension so as to obtain the crease. Preferably the working stroke is vertical and facing downwards, whereas the return stroke is vertical and facing upwards. Alternatively, the working stroke can be vertical and facing upwards and the return stroke vertical facing downwards.

In accordance with a possible embodiment, the connecting means comprises a frame. The frame preferably comprises a first crosspiece which is rigidly mounted on the pressing member and a second crosspiece arranged opposite the first one relative to the rest plane. Advantageously the first cutting portions are inserted in the frame between the first and second crosspiece.

Preferably, the frame comprises two risers that connect the first and second crosspiece thus shaping a preferably rectangular frame.

In accordance with a possible embodiment, the second crosspiece comprises a sliding surface, for example a surface made up of Teflon ®, facing inwardly the frame.

Preferably the first cutting portions being movable through the slot of the rest plane, are dragged by the first crosspiece, particuiarly by the frame, if present, both along the cutting stroke and the return stroke. As an alternative to the frame, the first crosspiece can be configured for generating the cutting stroke of the first cutting portions through the slot, thereby designating the return stroke to return devices, for example of the elastic type.

In accordance with a possible embodiment, the activating means are associated to the first crosspiece and then to the frame, if present.

Preferably a castle is integral with the first crosspiece and provided with sliding guides. A rack, preferably two racks, are fixed to the castle and respectively engage a toothed wheel which is associated to a motor solidly constraint to a frame.

Preferably the first cutting portions comprise two longitudinal laminae arranged parallel to one another and to the line of longitudinal extension and perpendicular to the rest plane. Each longitudinal lamina is suitable for interacting with a longitudinal edge of the slot of the rest plane so as to obtain a longitudinal cutting line of the end opening along the cutting stroke.

In accordance with a possible embodiment, each longitudinal lamina defines a respective blade. Such blade is preferably inclined in a plane perpendicular to the rest plane.

Preferably the longitudinal laminae are inserted between the first and the second crosspiece, in particular within the frame. Said longitudinal laminae are inter alia movable relative to the first and second crosspiece, for example to the frame, along an adjustable range of travel parallel to the line of longitudinal extension of the slot.

Preferably, the longitudinal laminae are mounted on opposite sides of a supporting plate comprising a base resting on the sliding surface of the second crosspiece, where present.

In accordance with a possible embodiment, the longitudinal laminae define a first slide channel parallel to the line of longitudinal extension and predisposed for receiving at least partially the pressing member.

In a possible embodiment, the longitudinal laminae also comprise a transverse blade-shaped portion defining an "L" blade wherein the transverse portions thereof may cooperate with a transverse fixed blade or with a fixed striker.

Preferably there are provided two anti-tip plates extending parallel to the line of longitudinal extension. The two anti-tip plates are arranged externally on opposite sides of the pressing member, said pressing member protruding from said anti-tip plates at one of the pressing portion thereof. In particular, each anti-tip plate defines a second slide channel with the pressing member, said slide channel being parallel to the line of longitudinal extension and suitable for receiving at least partially a longitudinal lamina.

Preferably there are provided elastic elements interposed between the longitudinal laminae and the supporting plates so as to maintain said longitudinal laminae in contact with a longitudinal edge of the slot of the rest plane.

The elastic elements may include spring washers for example arranged on opposite sides of a central washer. The elastic elements are housed in a seat of the supporting plate. A plurality of elastic elements can be disposed.

In accordance with a possible embodiment, the cutting members comprise second cutting portions configured for defining a fixed striker during the cutting stroke of the first cutting portions. Advantageously, the first cutting portions comprise a first transversal element arranged perpendicularly to the line of longitudinal extension and movable so as to pass through the slot along the cutting stroke. The second cutting portions comprise a second transversal element arranged perpendicularly to the line of longitudinal extension. The first and second transverse elements are predisposed for cooperating so as to obtain the line of transversal cutting. Preferably, the first transversal element is a transversal striker. Preferably the second transversal element is a transversal blade.

In accordance with a possible embodiment, the cutting members comprise reciprocal sliding means interposed between the first and second cutting portions, so as to enable the cutting stroke of the first cutting portions with respect to the second cutting portions.

Preferably, the reciprocal sliding means may include a shoe, said shoe being integral with the first cutting portions and sliding with respect to a guide integral with the second cutting portions.

Preferably adjustment means are provided configured for moving the cutting members along an adjustable range of travel parallel to the line of longitudinal extension.

In particular, the first and second cutting portions are integral one another along the adjustable range of travel.

In accordance with a possible embodiment, reciprocal sliding means are configured for enabling the integral movement of the first cutting portions and second cutting portions along the adjustable range of travel.

Preferably there are provided two sets of cutting members, each set being arranged at one end of the slot of the rest plane. The cutting members of each set are configured for fashioning an opening at the end of the crease.

The weakening method particularly provides one or more of the following steps.

In accordance with a possible embodiment, there is provided to move the pressing member along a return stroke. The first cutting portions are preferably integral with the pressing member during the return stroke, in accordance with a possible embodiment, there is provided to move the first cutting portions with respect to the second cutting portions, configured for defining a fixed striker during the cutting stroke of the first cutting portions.

In accordance with a possible embodiment, there is provided to move the cutting members along an adjustable range of travel, parallel to the line of longitudinal extension.

Further characteristics and advantages of the present invention will become more apparent from the indicative, and therefore non-limiting description of a preferred but not exclusive embodiment of a weakening device, as illustrated in the accompanying drawings in which:

- Figure 1 is a plan view of a packaging sheet;

- Figure 2 is a schematic perspective view of a machine for realizing blanks for packages of made-to-measure articles, according to a possible embodiment;

- Figure 3 is a schematic perspective view of a weakening device according to a possible embodiment;

- Figure 4 is a schematic perspective view of the weakening device of Figure 3 from a different angle, wherein some elements have been omitted so as to highlight others;

- Figures 5-6 are schematic perspective views of an enlarged detail of the weakening device of Figure 3 or 4 according to different angles;

- Figure 7 is a schematic front view of the weakening device of Figure 3 or 4;

- Figure 8 is a sectional view of an enlarged detail of the weakening device according to the line BB of Figure 7;

- Figure 9 is a schematic perspective view of some details of the weakening device of Figure 1 ;

- Figure 10 is an enlarged view of a detail of figure 9 illustrated with partially separate parts;

- Figures 11 and 12 are schematic views, respectively a side and perspective view, of a detail of Figure 10.

With reference to the attached figures, the numeral 1 overall indicates a machine for realizing blanks 2 for made-to-measure packages of articles, for example boxes of "American" type.

The machine 1 is suitable for being inserted in a plant for realizing made- to-measure packages of articles wherein, once the size (width and length) of the package plan development have been determined, the machine 1 provides to cut the needed packaging sheet 3 and realizes the blank 2 which will be further sent to an automatic or manual station which shall provide in turn to form the package. Figure 2 illustrates a packaging sheet 3, for example in the form of a cardboard, wherefrom the blank 2 will be fashioned. For realizing said blank 2, a starting point can be a plurality of packaging sheets 3 already prepared or a continuous module 4 of folded paper.

With reference to Figure 2, the machine 1 comprises a store 5 wherefrom the continuous module 4 is withdrawn. From said continuous module 4, single packaging sheets 3 are cut, for example by means of a first cutting device 6. Alternatively or in addition to the store 5, the machine 1 may comprise a store 7 wherefrom the packaging sheets 3 already predisposed, are taken. In the event of packaging sheets already prepared, the width of the package, and therefore the width of the packaging sheet 3, is previously established according to the type of product/article which is to be packed, whereas its length is adapted on a continuous basis, by consecutively pasting packaging sheets having same width.

In broad terms, the machine 1 comprises feeding means for feeding packaging sheets 3, configured for moving said packaging sheets through the devices predisposed for obtaining the blank 2. Such devices may for example comprise means for custom cutting of the packaging sheets 3. With the numeral 8 there is shown a weakening device suitable for realizing a weakening line 9 in the packaging sheets 3. The weakening device 8 is associated to a frame T of the machine 1.

Referring to Figure 1 , the weakening line 9 is a processing performed relative to a line of longitudinal extension L, along which the packaging sheet shall be folded so as to obtain two incident package walls, thereby facilitating the folding step.

in order to obtain the weakening line 9, the packaging sheet undergoes a double processing which leads to the realization of a crease 9a crossing the packaging sheet along the line of longitudinal extension L, and of two openings 9b at the end of the crease 9a. Said crease 9a connects the two end openings 9b thereof. Alternatively a single end opening can be also provided.

In particular each end opening 9b is open outwardly the packaging sheet 3. In other words, each end opening is defined by two longitudinal cutting lines 10 and a transversal cutting line 11. The terms longitudinal and transversal are particularly referred to directions being respectively parallel and perpendicular to the line of longitudinal extension L

With reference to Figure 3, the weakening device 8 comprises a rest plane 12 predisposed for receiving a packaging sheet. Referring to the attached figures, the rest plane 12 is, by way of example, horizontal. In Figure 4 and in other figures, the rest plane 12 has been omitted to highlight further characteristics of the weakening device.

The rest plane 12 includes at least one slot 13 which extends along a line of longitudinal extension L lying in the rest plane 12; this means that the slot 13 has a larger size than that of other slots which corresponds to a length thereof.

With reference to the attached figures, the slot 13 and the line of longitudinal extension L are, by way of example, horizontal.

When the packaging sheet is received, e.g., while resting on the rest plane 12, the line of longitudinal extension L of the slot 13 defines the line of longitudinal extension of the crease 9a which will thus be obtained on the packaging sheet.

In the illustrated example there is provided a single slot 3 crossing through the whole rest plane 12, along the line of longitudinal extension L. Alternatively, two end slots may be provided, connected by a groove suitable for fashioning the crease 9a.

With 14 it has been indicated a pressing member of which, in figure 3, a pressing portion 14a thereof is visible. The pressing member 14 extends for a length L parallel to the line of longitudinal extension L. By this definition it is meant that the pressing member 14 exhibits a larger size than the other ones, corresponding to a length L of the pressing member. With reference to the annexed figures, the pressing member 14 develops for example, horizontally, parallel to the line of longitudinal extension L. In particular, as visible in Figure 8, the pressing member 14 is made of a plate located along a plane perpendicular to the rest plane 12 and containing the line of longitudinal extension L. Preferably, the plate defining the pressing member 14 is arranged vertically and with one of its largest size (length I) parallel to the line of longitudinal extension L. The pressing member 14 is suitable for realizing, in the packaging sheet disposed on the rest plane 12, a crease 9a parallel to the line of longitudinal extension L. The pressing member 14 will be further described below, when referring to the section of Figure 8.

In accordance with a possible embodiment, the pressing member 14 is rigidly mounted on a first crosspiece 15a. Preferably the first crosspiece 15a is part of a frame 15 further comprising a second crosspiece 15b, disposed on the side opposite the first crosspiece 15a relative to the rest plane 12. Two risers 16a and 16b connect the first and second crosspiece thereby forming the frame 15, preferably of rectangular shape.

In accordance with a possible embodiment, the second crosspiece 15b includes a sliding surface 17, for example a surface made up of Teflon ®, facing inwardly the frame itself, the function of which wili be described later on.

With the numeral 18, activating means operationally connected to the pressing member 14 have been indicated. The activating means 18 are suitable for generating a working stroke 19 of the pressing member 14 in a plane perpendicular to the rest plane 12, said rest plane 12 containing the line of longitudinal extension L. The working stroke 9 is perpendicular to the line of longitudinal extension L and extends between a resting position of the pressing member 14 (for example that illustrated in Figure 3), and a pressing position (not shown) in which the pressing member 14 is able to form the crease 9a. With reference for example to the accompanying figures, the resting position of the pressing member 14 is a raised position wherein the pressing member 14 is kept at a distance from the rest plane 2 and thus from the packaging sheet, conversely, the pressing position is a lowered position in which the pressing member 14 is in contact with the packaging sheet disposed on the rest plane 12, pressing it relative to the line of longitudinal extension L so as to obtain the crease 9a. In other words, with reference to the accompanying figures, the working stroke 19 is vertical and directed downwards. Alternatively it may be eventually provided that the working stroke is vertical and facing upwards.

In accordance with a possible embodiment, of which the attached figures define a non-limiting example, the activating means 18 are associated to the first side 15a and then to the frame 15, if present.

For example, there can be provided a castle 20, integral with the first crosspiece 15a and supplied with sliding guides 21 , said sliding guides 21 being for example parallel, in particular vertical, with respect to the working stroke 19. A rack 22, preferably two racks, are fastened to the castle 20 engaging respectively with a toothed wheel 23 associated to a motor, not shown, which motor is integral with a fixed frame T of the weakening device 8.

By operating the motor, translation of the racks 22 and sliding of the castle 20 on the guides 21 is caused by the rotation of the toothed wheel 23.

Preferably the activating means 18 are suitable for generating a return stroke of the pressing member 14. The return stroke (not shown) is parallel to the working stroke 19 but in the opposite direction, in particular, it extends between the pressing position and the resting position.

in the example illustrated in the figures, the motor (not shown) can be operated in both directions so as to rotate the toothed wheels 23 in both directions, thereby causing a lowering or a raising of the castle 20 and consequently of the pressing member 14.

With the numerals 24a and 24b there were indicated respectively two sets of cutting members, each disposed at one end of the slot 3.

The cutting members of each set are configured for fashioning an opening 9b at the end of the crease 9a in a packaging sheet disposed on the rest plane 12.

The cutting members of each set comprise first cutting portions which are movable through the slot along a cutting stroke. More in detail, the first cutting portions are inserted in the frame 15, if present, between the first crosspiece 15a and the second crosspiece 15b.

A set of cutting members shall be described hereunder, with particular reference to the set 24b shown in detail in Figure 5. What has been described for the set 24b also applies to the set 24a, as illustrated by way of example in Figure 8. According to a possible embodiment, the first cutting portions comprise two longitudinal laminae 26a and 26b, each of which preferably defining a respective blade X, said longitudinal laminae 26a and 26b being arranged parallel to one another and to the line of longitudinal extension L and perpendicular to the rest plane 12. Each blade X is inclined in a plane being perpendicular to the rest plane. In particular each blade X is inclined so as to come in contact with the packaging sheet substantially at a point which in the cutting stroke 25 is slidabie from outside to inside of the packaging sheet, that is towards the transversal cutting line 1.

Each longitudinal laminae 26a, 26b is adapted to interact with a longitudinal edge of the slot 13 in order to receive a longitudinal cutting line 10 along the cutting stroke 25.

The longitudinal laminae 26a, 26b are inserted in the frame 5, if present, between the first crosspiece 15a and the second crosspiece 15b, said laminae 26a, 26b being slidabie relative to the first crosspiece 15a, in particular with respect to the frame 15, along an adjustable range of travel 27, parallel to the line longitudinal extension L The adjustable range of travel 27 can exhibit an approaching or distancing movement of the two sets of cutting members one to another.

The longitudinal laminae 26a, 26b define a first slide channel 28 parallel to the line of longitudinal extension L and adapted to receive at least partially the pressing member 14, in particular the pressing portion 14a thereof. Preferably, the longitudinal laminae 26a, 26b are mounted on opposite sides of a supporting plate 29 comprising a base 30 resting on the sliding surface 17, if present.

In accordance with a possible embodiment, two anti-tip plates 31 extend parallel to the line of longitudinal extension L and are arranged externally on opposite sides of the pressing member 14. in particular, said pressing member 14 protrudes from the anti-tip plates 31 , relative to the pressing portion 14a thereof (Figure 8).

Preferably each anti-tip plate 31 defines a second slide channel 32 with the pressing member 14, said slide channel 32 being parallel to the line of longitudinal extension L and adapted to receive at least partially a longitudinal lamina 26a, 26b.

Elastic elements 33 are interposed between the longitudinal laminae 26a, 26b and the supporting plate 29, so as to keep the blades in contact with the longitudinal edge of the slot 13 of the rest plane 12 (Figure 10). The elastic elements 33 may include spring washers 33a, for example, arranged on opposite sides of a centra! washer 33b. The elastic elements 33 are housed in a seat 33c of the supporting plate 29. As provided in the attached figures, a plurality of elastic elements 33 can be predisposed. In accordance with a possible embodiment, the cutting members of each set comprise second cutting portions configured for defining a fixed striker during the cutting stroke 25 of the first cutting portions.

Preferably the first cutting portions comprise a first transverse element, preferably a transverse striker 34, arranged perpendicularly to the line of longitudinal extension L and movable crossing through the slot 13 along the cutting stroke 25. If present, a free edge of the supporting plate 29 defines the transverse striker 34. Moreover, the second cutting portions comprise a second transverse element, preferably a transverse blade 35, second cutting portions being arranged perpendicularly to the line of longitudinal extension L. The first and second transverse element are fit for cooperating so as to obtain said transverse cutting line 11.

In the example shown in the attached figures, the longitudinal laminae 26a, 26b, with the respective supporting plate 29, define first cutting portions movable through the slots 13, along the cutting stroke 25 and the return stroke, said first cutting portions being dragged by the first crosspiece 15a, in particular by the frame 15, if present. As an alternative to the frame 15, the first crosspiece 15a may be configured for generating the cutting stroke 25 of the first cutting portions through the slot 13, by assigning the return stroke to return devices, for example of the elastic type.

In other words, connecting means are provided which are operationally interposed between the pressing member 14 and the cutting members, said connecting means being configured for making the first portions integral with the cutting member 14 during the working stroke 19, so as to generate the cutting stroke 25. Preferably the connecting means are also configured for making the first cutting portions integral with the pressing member 14 during the return stroke.

In the example illustrated in the figures such connecting means are for example defined by the first crosspiece 15a, particularly by the frame 15. Advantageously, the cutting members of each set comprise reciprocal sliding means interposed between the first cutting portions and the second cutting portions, so as to enable the cutting stroke 25 of the first cutting portions with respect to the second cutting portions. With reference to the attached figures, in particular to Figure 6, the reciproca! sliding means may comprise, by way of example, a sliding shoe 36, integral with the first cutting portions (for example with the supporting plate 29, namely with the longitudinal laminae 26a, 26b); said sliding shoe being s!idabie with respect to a guide 37 integral with the second cutting portions (for example with the transverse blade 35).

Preferably the first cutting portions and the second cutting portions are integral with one another along the adjustable range of travel 27. In particular, the reciprocal sliding means are configured for enabling the integral movement of the first and second cutting portions along the adjustable range of travel 27,

In order for the cutting members to be moved along the adjustable range of travel 27, there can be provided adjustment means for example comprising a rack 38 integral with the second cutting portions (in particular with the transverse blade 35). Advantageously it can be also provided a sliding bar 39 slidably connected to the second cutting portions {in particular to the transverse blade 35). A toothed wheel 40 set in rotation by a motor 41 in both directions, engages with the rack 38 (preferably with both racks 38, each associated with a set of cutting members). Alternatively to what has been illustrated above, only one cutting set can be provided at one end of the slot 13.

When in use, the weakening device 8 provides to prepare a packaging sheet 3 on the rest plane 12 and to realize a crease 9a parallel to the line of longitudinal extension L on the packaging sheet by moving the pressing member 14 along the working stroke 19.

At least one opening 9b, preferably two openings 9b at the end of the crease 9a, are realized by moving the first cutting portions through the slot 13 along the cutting stroke 25, at the same time when the crease 9a is realized. The working stroke 19 of the pressing member 14 causes the cutting stroke 25 of the first cutting portions, in particular, the first cutting portions are integral with the cutting member 14 during the working stroke 19 so as to generate the cutting stroke 25,

Preferably, the pressing member 14 is moved along the return stroke and the first cutting portions are integral with the pressing member 14 during the return stroke.

During the cutting stroke 25, the first cutting portions are moved with respect to the second cutting portions, configured for defining a fixed striker during the cutting stroke of the first cutting portions. The cutting members are moved along the adjustable range of travel 27 parallel to the line of longitudinal extension L for defining the size of the of the end openings 9b, in particular the length of the longitudinal cutting lines 10.

The proposed solution is able to achieve in a single passage both the crease and the end opening (or end openings) thereof, in the cutting stroke 25, the longitudinal laminae 26a, 26b (each provided with a blade X), make a scissor movement with the longitudinal edges of the slot 13, whereas the transverse striker 34 acts as a striker for the transverse blade 35, which remains fixed during the cutting stroke 25.

In a possible alternative embodiment, the longitudinal laminae also include a transverse blade portion (in other words, the first cutting portions comprise an "L"-shaped blade) and the transverse blade 35 may be replaced with a simple fixed striker.

The longitudinal laminae 26a, 26b thoroughly cross the packaging sheet. in other words, said longitudinal laminae 26a, 26b preferably perform a maximum cutting stroke 25. The inclined configuration of the blade X allows to not have an impact onto the packaging sheet with an entire plane, thereby realizing the cutting substantially relative to a movable point along the longitudinal cutting line 10. In such a way a progressive effort is applied on the packaging sheet during the cutting.

The adjustment of the cutting members position along the adjustable range of travel 27 enables to obtain the longitudinal cutting lines 10 having a greater length than that obtainable with a single cutting stroke of the cutting member. Consider for example the case in which the length of the longitudinal cutting iine 10 is equal to Y + K, and the length obtainable with a single cutting stroke is equal to Y. In this case, the cutting members are placed at the ends of the packaging sheet and a first cutting stroke (working stroke) is performed so as to obtain a longitudinal cutting line equal to Y. Subsequently, each set of cutting members is brought towards the center of the packaging sheet for a stretch equal to K (for example by activating the adjustment means), and a second cutting stroke (working stroke) is carried out.

During the pressing operation performed by the pressing member 14, the anti-tip plates 31 are integral with said pressing member 14, preventing the packaging sheet's edges from rising.

Claims

1. A weakening device (8) fit for realizing a weakening line (9) in packaging sheets (3) for realizing blanks (2) for packages of articles, comprising:

- at least one rest plane ( 2) fit for receiving a packaging sheet (3), said rest plane (12) comprising at least one slot (13) extending along a line of longitudinal extension (L) lying in said rest plane (12),

- a presser member (14) extending for a length (I) parallel to said line of longitudinal extension (L) and fit for realizing a crease (9a) parallel to said line of longitudinal extension (L), in a packaging sheet (3) arranged on said rest plane ( 2) and in a configuration of use of the weakening device (8),

- activating means (22, 23) operationally connected to said presser member (14) and fit for generating a working stroke (19) of said presser member (14) in a plane perpendicular to said rest plane (12) and containing said line of longitudinal extension (L), said working stroke (19) being perpendicular to said line of longitudinal extension (L) between a resting position and a pressing position, wherein said presser member (14) is fit for realizing said crease (9a),

- at least one set of cutting members (26a, 26b, 34, 35) arranged at least at one end of said slot (13), said cutting members being configured so as to realize an opening (9b) at the end of said crease (9a), in a packaging sheet (3) arranged on said rest plane (12) and in a configuration of use of the weakening device, said opening (9b) at the end of said crease (9a) being defined by two longitudinal cutting lines (10) and a transverse cutting line (1 1), and wherein said cutting members comprise first cutting portions (26a, 26b, 34) that are movable through said slot (13) along a cutting stroke (25),

- connecting means (15a, 15b; 15) that are operationally interposed between said presser member (14) and said cutting members, and configured to make said first cutting portions integral with said presser member (14) during said working stroke ( 9) so as to generate said cutting stroke (25).

2. The weakening device according to claim 1 , wherein said activating means is fit for generating a return stroke of said presser member (14) between said pressing position and said resting position, and wherein said connecting means are configured to make said first cutting portions integral with said pressing member (14) during said return stroke.

3, The weakening device according to c!aim 2, wherein said connecting means comprise a frame (15) comprising a first crosspiece (15a) whereon said presser member (14) is rigidly mounted, as well as a second crosspiece (15b) arranged opposite the first crosspiece ( 5a) with respect to said rest plane (12), and wherein said first cutting portions are inserted in said frame (15) between said first crosspiece (15a) and said second crosspiece (15b).

4, The weakening device according to one or more of the preceding claims, wherein said first cutting means comprises two iongitudinal laminae (26a, 26b), each preferably defining a respective blade (X), and arranged parallel to each other and to said line of Iongitudinal extension (L) and perpendicular to said rest plane (12), and wherein each Iongitudinal lamina (26a, 26b) is fit for interacting with a Iongitudinal edge of said slot (13) so as to obtain a Iongitudinal cutting line (10) along said cutting stroke (25).

5. The weakening device according to claim 4, when dependent upon claim 3, wherein said Iongitudinal laminae (26a, 26b) are inserted in said frame (15) between said first crosspiece (15a) and said second crosspiece (15b) and are slidable with respect to said frame (15) along an adjustable range of travel (27) parallel to said line of Iongitudinal extension (L).

6. The weakening device according to claim 5, wherein said iongitudinal laminae (26a, 26b) define a first slide channel (28) parallel to said line of Iongitudinal extension (L) and fit for receiving said presser member (14) at least partially.

7. The weakening device according to claim 6, comprising two anti-tip plates (31) extending parallel to said line of longitudinal extension (L) and arranged externally on opposite sides of said presser member (14), said presser member (14) protruding from said anti-tip plates (31) at one of the pressing portions (14a) thereof, and wherein, with said presser member (14) each anti-tip plate (31) defines a second slide channel (32) parallel to said line of longitudinal extension (L) and fit for receiving one longitudinal lamina (26a, 26b) at least partially.

8. The weakening device according to claim 7, comprising elastic elements interposed between said longitudinal laminae (26a, 26b) and a supporting plate (29) to keep the longitudinal laminae in contact with a longitudinal edge of the slot (13) of the rest plane (12).

9. The weakening device according to one or more of claims 4 to 8, wherein each one of the longitudinal laminae (26a, 26b) defines a respective inclined blade (X) within a plane perpendicular to said rest plane (12).

10. The weakening device according to one or more of claims 4 to 9, wherein said cutting members comprise second cutting portions configured to define a fixed striker during the cutting stroke of the first cutting portions,

wherein said first cutting portions comprise a first transverse element, preferably a transverse striker (34), arranged perpendicularly to said line of longitudinal extension (L) and that is movable, crossing through said slot (13) along said cutting stroke (25),

and wherein said second cutting portions comprise a second transverse element, preferably a transverse blade (35) that is arranged perpendicularly to said line of longitudinal extension (L),

said first and second transverse elements being fit for cooperating so as to obtain said transverse cutting line (11).

11. The weakening device according to claim 10, wherein said cutting members comprise reciprocal sliding means (36, 37) interposed between said first cutting portions and said second cutting portions to enable the cutting stroke of said first cutting portions, with respect to said second cutting portions.

12. The weakening device according to one or more of the preceding claims, comprising adjustment means (38-41) configured to move said cutting members along an adjustable range of travel (27) parallel to said line of longitudinal extension (L).

13. The weakening device according to claim 12, when dependent upon claim 0 or 1 1 , wherein said first cutting portions and said second cutting portions are integral with each other along said adjustable range of travel (27).

14. The weakening device according to claim 3, when dependent upon claim , wherein said reciprocal sliding means (36, 37) are configured to enable integral movement of said first cutting portions and said second cutting portions along said adjustable range of travel (27).

15. The weakening device according to one or more of the preceding claims, comprising two sets of cutting members, each set being arranged at one end of said slot (13), wherein the cutting members of each set are configured to realize an opening (9b) at the end of said crease (9a) in a packaging sheet (3) arranged on said rest plane (12) and in a configuration of use of the weakening device, said opening (9b) at the end of said crease (9a) being defined by two longitudinal cutting lines (10) and a transverse cutting line (11).

16. A machine (1) for realizing blanks for made-to-measure packages of articles, comprising:

feeding means for feeding packaging sheets;

means for custom cutting said packaging sheets;

at ieast one weakening device (8) according to one or more of the preceding claims.

17. A weakening procedure suitable for realizing a weakening line (9) in packaging sheets (3) for realizing blanks (2) for packages of articles, comprising:

- arranging a packaging sheet (3) on a rest plane (12) comprising at least one slot (13) extending along a line of longitudinal extension (L) lying in said rest plane (12),

- realizing a crease (9a) parallel to said line of longitudinal extension (L) on said packaging sheet (3) by moving a presser member (14) along a working stroke (19),

- realizing at least one opening (9b) at the end of said crease (9a), by moving first cutting portions of cutting members through said slot (13) along a cutting stroke (25), said opening being defined by two longitudinal cutting lines (10) and a transverse cutting line (11) and

said first cutting portions being integral with said presser member (14) during said working stroke (19) so as to generate said cutting stroke (25).

18. The weakening procedure according to claim 17, comprising moving said presser member (14) along a return stroke path, said first cutting portions being integral with said presser member (14) during said return stroke.

19. The weakening procedure according to claim 17 or 18, comprising moving said first cutting portions with respect to second cutting portions configured to define a fixed striker during the cutting stroke of the first cutting portions.

20. The weakening procedure according to one or more of claims 17 to 19, comprising moving said cutting members along an adjustable range of travel (27) parallel to said line of longitudinal extension (L).