Method and installation for applying foil material onto successive sheets

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DESCRIPTION

Method and installation to apply sheet material on successive sheets

Technical field

The present invention relates generally to a method and installation for applying sheet material on successive sheets, especially financial title sheets. The present invention is especially applicable in the context of the production of security documents, such as banknotes.

Background of the invention

The application of sheet material on sheets, especially sheets of financial securities, is as such already well known in the art. Such an application is typically aimed at providing financial securities with additional security elements, such as in particular the so-called OVD (Optically Variable Devices). OVDs are typically in the form of a sheet patch or laminate comprising a layer that optically diffracts (usually a metallized layer) that produces optically variable effects. OVDs are known in particular under the name of KINEGRAM®, which is a registered trademark of OVD Kinegram AG, a member of the Leonhard Kurz Group.

OVDs are typically supplied in the form of a continuous film or band of carrier material that carries transfer elements that are ultimately to form the actual OVDs. These are usually applied using so-called hot foil stamping techniques, which use combined pressure and temperature to activate a layer of adhesive provided on the transfer elements and cause the transfer thereof from the carrier material onto the sheets or strip that are being treated

Methods and installations for practicing hot foil stamping techniques are described for example in international applications No. WO 94/13487 A1, WO 97/01442 A1, WO 97/35271 A1, WO 97/35794 A1, WO 97 / 35795 A1, WO 97/36756 A1, WO 03/043823 A1, WO 2005/102733 A2, and European patent application EP 0 965 446 A1.

In addition to the application of the OVD on financial titles, it has also been proposed to cut windows in financial titles and cover these windows with a film of sheet material, usually transparent. Such a solution is for example proposed in International application No. WO 95/10420 A1. In contrast to the OVD, the layer of sheet material that is applied to cover windows is relatively thicker and more resistant since it has to withstand greater mechanical stress and be self-supporting in the region of the window.

Similarly, it has also been proposed to reinforce regions of reduced thickness created in financial securities by providing a film of sheet material on said regions. A method for reinforcing security documents provided with at least one area of ​​reduced thickness is for example described in International Application WO 2004/024464 A1.

The forecast of windows in financial titles can be carried out in different ways. A method and installation for cutting sheet windows using mechanical cutting tools are for example described in International Application No. WO 03/092971 A1. A method and installation for cutting sheet windows using a laser cutting tool is for example described in International Application WO 2004/096482 A1.

The coverage of the windows by sheet material is described in greater detail in International applications No. WO 2004/096541 A1 and WO 2005/068211 A1.

In accordance with International Application No. WO 2004/096541 A1, sheet material is applied in the form of successive strips of sheet material that are cut upstream of an application unit. The application unit is basically similar to those used to carry out hot foil stamping with the main difference that the strips of sheet material are transferred completely onto the sheets. In this context, it is more appropriate to say that the application unit performs the stratification of the sheet material on the sheets, instead of the stamping, whose process involves the transfer of an element from a carrier band on the sheets and the recovery of the carrier band used.

The solution of International application No. WO 2004/096541 A1 has been found quite difficult to implement since it requires precise cutting and positioning of the stratified strips with respect to the sheets. This particular prior art solution requires a suction system specifically designed to properly hold and transport the laminate strips so that they are brought into contact with the sheets in the desired positions.

The solution of International application No. WO 2004/096541 A1 is also applicable only for laminate strips that have a minimum length and is not particularly suitable for applying small patches.

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size of sheet material on the sheets.

There is therefore a need for an improved method and installation to apply sheet material on successive sheets. Such improved method and installation form the subject of European Patent Application No. 07103051.4 entitled "METHOD AND INSTALLATION FOR APPLYING SHEET MATERIAL ON SUCCESSIVE LEAVES" filed on February 27, 2007 in the name of this Applicant (published as EP 1 961 578 A1), as well as the subject of International Application No. PCT / IB2008 / 050626 of February 21, 2008 (published as WO 2008/104904 A1) claiming priority of EP 07103051.4.

This improved method includes the following operations. In a first operation, individual sheets are transported in succession along a sheet transport path. In a second operation, at least one continuous web of sheet material is applied to the individual sheets along a direction substantially parallel to a direction of travel of the individual sheets, thereby forming a continuous flow of sheets joined together. by at least one of said continuous bands of sheet material. In a third operation, at least said continuous web of sheet material is cut in such a way that the continuous flow of sheets is separated again into individual sheets leaving parts of sheet material on the sheet. The cutting of at least said continuous web of sheet material is performed in positions located on the sheets such that the portions of sheet material that remain on the sheets do not extend beyond the anterior and posterior edges of the sheets.

An installation for carrying out the above method comprises (i) a sheet-by-sheet feeding station for feeding the individual sheets, (ii) a sheet application unit for applying at least said continuous web of sheet material on the sheets individual, (iii) a cutting unit, located downstream of the sheet application unit, for cutting at least said continuous web of sheet material, and (iv) a sheet delivery post to receive the individual sheets.

Thanks to the previous method and installation, a precise application of the sheet material on the successive sheets is ensured, while ensuring that the sheet material applied does not cause disturbances during further treatment of the sheets in the downstream processes. In fact, since the cutting of the sheet material is carried out in positions located on the sheets such that the remaining portions of sheet material on the sheets do not extend beyond the front and rear edges of the sheets, it is not visible affected the appropriate alignment of the leaves in the downstream processes (whose alignment uses the front edge of the leaves as a reference, or as the case may be the rear edge).

According to an embodiment of the above method and installation, the cutting can for example be carried out by means of mechanical cutting tools without causing damage to the blades. According to an alternative embodiment, and provided that the sheet material is made of plastic or any other material that can be cast, the cutting can be performed by melting the sheet material using a heating element (such as a heated electric wire) . Even in accordance with an alternative embodiment, the cutting of the sheet material can be carried out using a laser beam. The tests carried out by the applicant have shown that laser cutting is particularly efficient when selectively cutting the sheet material without damaging the sheets.

A main advantage of laser cutting is that the cutting operation can be carried out "without contact", that is to say the laser cutting unit as such is not brought into contact with the sheet material, but instead simply laser beam produced by the laser cutting unit.

However, a difficulty arises in connection with the evacuation of the remaining parts of the web or continuous bands of the sheet material that are not to remain on the sheets. Such evacuation is preferably performed by aspiration as suggested in European Patent Application No. 07103051.4 and in International Application No. PCT / IB2008 / 050626. Such difficulty is exacerbated in the case of cutting the sheet material by means of a laser since specific means need to be provided to carry out the evacuation without interfering with the laser.

Summary of the Invention

A general purpose of the invention is thus to further improve the known methods and facilities for applying sheet material on successive sheets.

One purpose of the invention is in particular to provide a solution that is less complicated to implement than known solutions.

Another purpose of the invention is to provide a solution that allows the application of the sheet material in a precise manner on the sheets.

Still another purpose of the present invention is to provide a solution that allows the application of the sheet material on the sheets without this affecting the further treatment of said sheets in the downstream processes.

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Still another purpose of the present invention is to provide a solution that is capable of applying a wide range of sheet material part sizes on the sheets.

More precisely, a particular purpose of the present invention is to provide a solution of the type proposed in European Patent Application No. 07103051.4 and in International Application No. PCT / IB2008 / 050626 in which the cutting operation is performed by means of a laser beam and wherein the remaining parts of the web or continuous bands of sheet material that are not to remain on the sheets are properly evacuated.

These purposes are achieved thanks to the solution defined in the claims.

The method according to the invention comprises the following operations. In a first operation, individual sheets are transported in succession along a sheet transport path. In a second operation, at least one continuous web of sheet material is applied to the individual sheets along a direction substantially parallel to a direction of travel of the individual sheets, thereby forming a continuous flow of sheets joined together by at least said continuous web of sheet material. In a third operation, at least said continuous web of sheet material is cut by means of a laser beam so that the continuous flow of sheets is separated from the new one in individual parts, leaving parts of the sheet material on the sheet. The cutting of at least said continuous web of sheet material is performed in positions located on the sheets such that the portions of sheet material that remain on the sheets do not extend beyond the front and rear edges of the sheets. In addition, the remaining parts of at least said continuous web of sheet material that are not to remain on the sheets are evacuated by aspiration, said evacuation being carried out by direct aspiration of the remaining parts at least in a first position downstream and close to the cutting position where at least said continuous web of sheet material is cut by the laser beam.

Thanks to an earlier method, a precise application of the sheet material on the successive sheets is ensured, while ensuring that the sheet material applied does not cause disturbances during further treatment of the sheets in the downstream processes. In fact, since the cutting of the sheet material is performed in positions located on the sheets such that the portions of sheet material that remain on the sheets do not extend beyond the front and rear edges of the sheets, they do not an appropriate alignment of the leaves is affected in the downstream processes (whose alignment uses the front edge of the leaves as a reference, or as the case may be the rear edge).

A priori, cutting the sheet material at positions on the sheets would appear to be detrimental to the integrity of the sheets. Tests have shown however that cutting the sheet material can be carried out on the surface of the sheets using a laser without any major problem. The tests carried out by the Applicant have in fact demonstrated that laser cutting is very efficient by selectively cutting the sheet material without damaging the sheets.

Advantageous embodiments of the invention form the object of the dependent claims and are described below.

According to an advantageous embodiment, the cutting of at least said continuous web of sheet material is performed immediately afterwards from an anterior edge of the sheets and immediately before a posterior edge of the sheets over a total width of the continuous web of the material. sheet, so that a continuous part of the sheet material is allowed to remain on each sheet. In such a case, it is particularly preferable to carry out the cutting in unprinted margins of the sheets.

According to an alternative embodiment, the cutting of at least said continuous web of sheet material is performed in a plurality of positions along a length of the continuous web of sheet material, such that a plurality of different parts of sheet material is allowed to remain on each sheet.

In the context of the invention, the continuous strip or bands of sheet material can be advantageously supplied in the form of a roll of the sheet material.

In the context of the production of documents, such as security documents, in which the sheets may carry a grouping of prints or marks arranged in an array of rows and columns, at least one continuous web of sheet material is applied to the length of each column of impressions.

The present invention is applicable in particular to cover windows or openings cut in the sheets prior to the application of the web or continuous bands of sheet material. In this particular case, it is advantageous to apply a sheet material that is substantially transparent.

The sheet material is preferably a plastic laminate comprising a layer of adhesive that is brought into contact with the surface of the sheets. This adhesive layer is advantageously a pressure activated and / or temperature activated adhesive layer that is activated during application only in corresponding locations

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to the parts of sheet material that must remain on the sheets. The cutting is preferably carried out in this case in locations where the layer of adhesive has not been activated, advantageously in an immediate proximity of the parts of sheet material that are to remain on the sheets. In this case, although peripheral parts of the sheet material do not have to adhere to the sheets after the application process, their dimensions can be minimized. In addition, it is common practice to subject the sheets after application of the sheet material to an "intaglio" or chalcography printing process, especially for the purpose of overprinting the sheet material. As a result of the "intaglio" printing, the peripheral parts of the sheet material are made to adhere to the sheets due to the combined effect of temperature and pressure inherent in the "intaglio" printing.

An installation for carrying out the above method forms the subject of the dependent claims, whose installation generally comprises (i) a sheet-by-sheet feeding post for feeding the individual sheets, (ii) a sheet application unit for applying to the minus said continuous web of sheet material on the individual sheets, (iii) a laser cutting unit, located downstream of the sheet application unit, to cut at least said continuous web of sheet material, and (iv) a leaf delivery station to receive the individual sheets. Said installation further comprises at least a first suction unit that includes a suction head arranged adjacent to the sheets to carry out the suction of the remaining parts of at least said continuous web of sheet material in said first position downstream and close to the cutting position in which at least said web of sheet material is cut by the laser beam.

The suction head advantageously comprises a suction opening to aspirate the remaining parts of at least said continuous web of sheet material and at least one suctionless support part that rests against the sheets in a position not covered by at least said band Continuous sheet material. Such a suction head configuration makes it possible to ensure proper aspiration of the portions of sheet material to be evacuated, while preventing the sheets from being sucked into the suction head. In a preferred embodiment, the position of each suction head is adjustable along and / or transversely to the direction of travel of said blades.

According to another preferred embodiment of the installation, a second suction unit is provided and arranged in a second position located downstream of the first position to evacuate the remaining parts of at least said continuous web of sheet material that could have been evacuated. for the first suction unit. In such a case, the first and second suction units may be conveniently operatively coupled to each other, that is to say using a common suction source.

A device for checking that the remaining parts of sheet material have been properly evacuated is also preferably provided.

According to another preferred embodiment of the installation, means are also provided for checking the passage of an anterior and / or posterior edge of the sheets and adjusting the operation of the laser cutting unit according to the passage of the anterior and / or posterior edge. of the leaves. This ensures stable operation and precise cutting of the sheet material in certain positions on each sheet.

Brief description of the drawings

Other features and advantages of the present invention will appear more clearly upon reading the following detailed description of embodiments of the invention that are presented only by way of non-restrictive examples and illustrated by the accompanying drawings in which:

Fig. 1 is a schematic side view of a sheet-fed treatment machine for applying sheet material on successive sheets as described in European Patent Application No. 07103051.4 and in International Application No. PCT / IB2008 / 050626.

Fig. 2 is a schematic top view of two successive sheets joined together by a plurality of continuous bands of sheet material which are applied on the sheets along a direction parallel to a direction of travel of the sheets;

Fig. 3 is a schematic top view of a single sheet after cutting the plurality of continuous bands of sheet material of fig. two;

Fig. 4 is a schematic side view of a sheet-fed treatment machine for applying sheet material on successive sheets in accordance with a preferred embodiment of the invention;

Fig. 5 is a partial perspective view of the laser cutting unit and the aspiration unit used in the embodiment of fig. 4;

Figs. 6a and 6b are schematic side and bottom views, respectively, of a head arrangement of

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suction of the suction unit of fig. 5;

Fig. 7 is a schematic top view showing the respective locations of two adjacent suction heads according to the embodiment of fig. 4;

Fig. 8 is a schematic side view of another embodiment of a suction system that can be used in the context of the invention;

Fig. 9 is a schematic top view of a single sheet after cutting the plurality of continuous bands of sheet material of fig. 2 according to a variant of the invention; and

Fig. 10 is a partial top view of a web of sheet material illustrating a possible alternative of cutting the web of sheet material.

Detailed description of embodiments of the invention

Fig. 1 is a schematic side view of a sheet-fed treatment machine for applying a sheet material on successive sheets as described in European Patent Application No. 07103051.4 and in International Application No. PCT / IB2008 / 050626 described above. Its configuration is almost identical to prior art hot foil stamping machines, such as that described in International applications No. WO 97/35721 A1, WO 97/35794 A1, WO 97/35795 A1 and WO 97/36756 A1. It comprises a feeding station 1 sheet by sheet to feed individual sheets S to a sheet application unit 2, whose sheet application unit 2 basically comprises an application cylinder 21 (in this case a four-segment cylinder that has four segments each capable of holding and transporting a sheet from the sheet-by-sheet feed station 1) cooperating with a plurality of rows of pressure rollers 22 which are elastically pressed against the circumference of the application cylinder 21 by means of pneumatic cylinders (not referenced). In this case, three pairs of rows of pressure rollers 22 are pressed against the circumference of the application cylinder 21.

The sheet material is conveniently supplied from a feed roll 20 in the form of a continuous web of sheet material 200. This continuous web 200 is fed to the application cylinder 21 so that it is sandwiched between the application cylinder circumference 21 and the leaves S. In the context of the production of security documents, such as banknotes, each sheet S is typically provided with a grouping of prints or P marks arranged in an array of rows and columns (as for example illustrated in figs. 2 and 3). It will be understood thus that at least one feed roll 20 will be provided so that it supplies a corresponding strip of sheet material 200 along each column of prints P.

The sheet material 200 is preferably made of a plastic laminate, preferably substantially transparent, such as, but not limited to, a polyester (PET) or polycarbonate (PC) material comprising an adhesive layer that is brought into contact with the surface of the leaves. This sheet material 200 may optionally be provided with a partially demetallized layer such as that sold under the name of KINEGRAM zero.zero®, which is a registered trademark of OVD Kinegram AG.

The adhesive layer is preferably a pressure activated and / or temperature activated adhesive layer that is activated during application only at locations corresponding to the parts of sheet material that are to remain on the sheets. Alternatively, a two-compound adhesive could be used in which one adhesive compound is applied on the sheet material and the other adhesive compound is applied on the sheets before the sheet application (as described for example in the application International No. WO 2005/068211 A1.

The application cylinder 21 is provided with a plurality of heated stamping members (not shown) in the locations where the sheet material 200 is to be applied on the S sheets. International application No. WO 2005/102733 A2, provides a detailed description of an application cylinder 21 equipped with such stamping members. It is sufficient to understand that the stamping members are sized according to the parts of the adhesive layer to be activated on the sheet material 200 and that the pressure rollers 22 are designed for rolling contact with said stamping members.

For example, in the context of the embodiment illustrated by figs. 2 and 3, whose embodiment will be described below, it has been considered to apply each continuous web of sheet material 200 so that a continuous part thereof, designated with the reference number 200 *, is allowed to remain on each sheet S. In other words, each stamping member on the application cylinder 21 is sized to exhibit the shape of a strip whose length corresponds to the length of the adhesive layer to be activated on the web of sheet material 200.

After application of the continuous bands of sheet material 200 on the individual sheets S, a

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continuous flow of sheets S joined together by the continuous bands of sheet material 200, as schematically illustrated in fig. two.

With reference again to fig. 1, the continuous flow of sheets S joined by the continuous bands of sheet material 200 is fed to a refrigeration unit comprising a cooling roller 23 cooperating with conveyor belts 24. In the illustrated embodiment, the conveyor belts 24 are driven rotating so that they continue counterclockwise in fig. 1 and reverse the continuous flow of sheets S from the surface of the application cylinder 21, against the circumference of the cooling roller 23 (whose roller 23 rotates clockwise in Fig. 1), and on a plate of horizontal guide 25.

The refrigeration unit is not required as such and can be omitted. The tests have shown, however, that the refrigeration unit can be advantageous because it allows the temperature stabilization and regulation of the treated sheets S as well as the downstream part of the sheet application unit 2 where the cutting unit , designated by reference number 5, is located.

The cutting unit 5 is located downstream of the sheet application unit 2, in the vicinity of the horizontal guide plate 25, for cutting the continuous bands of sheet material 200. In the illustration of fig. 1, the cutting unit 5 is a mechanical cutting unit comprising a cutting cylinder 50 as described in greater detail in European Patent Application No. 07103051.4 and in International Application PCT / IB2008 / 050626.

As a result of this cutting, the continuous flow of sheets S is again separated into individual sheets S with parts of sheet material remaining, designated by reference numeral 200 * in fig. 3, on the sheets S. The separation is necessary since the sheets s have to be transferred to a downstream chain conveyor system, generally designated by the reference number 3 in fig. 1.

As illustrated in fig. 1, a suction drum 26 is located below the conveyor belts 24, downstream of the guide plate 25 and the cutting unit 5. The circumferential surface of the suction drum 26 is tangent to the plane in which they are transported S sheets in this region. The suction drum 26 preferably has a dedicated drive that is controllable in speed and / or controllable in position (not shown), which comprises, for example, an electric motor whose speed can be adjusted. A circumferential speed of suction drum 26 is controlled in such a way that the suction drum 26 is initially at the transport speed of the conveyor belts 24, is then accelerated to a speed that is slightly greater than the speed of the conveyor system 3 chain, and then it is decelerated again in order to allow the transfer of the sheet S with which the suction drum 26 cooperates in a corresponding one of the grab bars 30 of the chain conveyor system 3. This "over speed" is required in order to cover a necessary displacement of the sheet S between the suction drum 26 and the chain conveyor system 3.

Once transferred to the chain conveyor system 3, the treated sheets are then transported to a delivery stacking unit of a sheet delivery station 4.

Fig. 2 is a schematic illustration of the flow of sheets S that would be formed as a result of the application of the continuous bands of sheet material 200 downstream of the application cylinder 21 in fig. 1. In fig. 2, the reference number 100 designates windows that have been provided on the sheets S before the application of the continuous bands of sheet material 200. Such windows could be provided online in the same treatment machine where the sheet material 200 is applied (as for example has been proposed in International Application No. WO 2004/096541 A1) or in a separate machine.

In fig. 2, which illustrates sheets S each of which carries a grouping of prints P arranged in eight rows and five columns (whose array arrangement is simply illustrative), five continuous bands of sheet material 200 are applied along one direction parallel to the direction of transport of sheets (indicated by the vertical arrows in fig. 2), ie a continuous band 200 per column of prints P. It will be appreciated that more than one continuous web of sheet material 200 could be applied per column of prints P, for example in case windows are provided in more than one position along the length (ie transversely to the direction of transport of sheets) of each print P. In the illustrated example, print P is provided with two windows 100 that are covered by the same web of sheet material 200.

In fig. 2, the references lm and tm respectively designate an anterior margin and a posterior margin of the sheets S, that is to say parts of the sheets that do not carry any printing P. Although these margins will also be referred to as "unprinted margins", it will be understood that such margins could however be provided with printed marks, for example brands that are exploited in the context of logistics management and / or quality of the sheets.

In fig. 2, the dashed lines designated by references C1 and C2 in the front and back of the sheets, respectively, are indicative of the locations where the cutting operations are to be carried out in the context of this first embodiment . In other words, according to this first embodiment, the continuous bands of sheet material 200 are cut immediately after a leading edge of the S sheets (more

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precisely within the anterior margin lm without printing) and immediately before a posterior edge of the sheets S (more precisely within the posterior margin tm without printing) over a total width of the continuous bands 200. As a result, as illustrated by the fig. 3, continuous parts of sheet material, whose parts are designated by reference numbers 200 *, are allowed to remain on each S sheet.

Fig. 4 schematically illustrates an embodiment of an installation for carrying out the method of the invention, the embodiment of which differs from that illustrated in fig. 1 because the mechanical cutting system 5, 50 is replaced by a 5 * laser cutting unit. All other constituent parts of the installation are identical to the installation illustrated in fig. 1 and therefore are designated by the same reference numbers as in fig. 1. As will be apparent below, the laser cutting unit 5 * comprises in this embodiment a plurality of laser units 500 (in particular three units) arranged above the horizontal guide plate 25, the laser beams generated by the units being directed laser 500 down towards the surface of the S sheets being transported under it. Downstream of the laser cutting unit 5 * with respect to the direction of travel of the S-blades, a first suction unit is also provided, designated globally by reference number 550.

Fig. 5 is a partial perspective view of the 5 *, 500 laser cutting unit and the aspiration unit 550 used in the embodiment of fig. 4. As already mentioned, the laser cutting unit 5 * comprises in this preferred example three units 500 mounted vertically above the path of the blades. These laser units 500 may be any suitable laser units, such as CO2 laser units or Nd-YAG laser units, as commercially available from Macsa Laser Solutions (www.macsalaser.com) and KBA-Metronic (www.kba -metronic.com). A CO2 laser unit available from the previous suppliers under the product designation "K-1060 Plus" was successfully used to carry out the cutting process.

In the preferred embodiment and as schematically illustrated in fig. 5, a laser unit 500 is used to cut two contiguous continuous bands of sheet material 200 applied on the sheets (two of such bands of sheet material 200 being schematically illustrated in Fig. 5 by dashed lines) . Depending on the application, only one or more of two adjacent bands of sheet material 200 could be cut by the same laser unit 500. Each laser unit 500 can carry out a cutting operation over a distance, transversely to the direction of travel of the sheets, of approximately 200 to 250 mm. In other words, the three laser units 500 can jointly cover a distance of 600 to 750 mm sufficient to handle most of the sheet formats used in the context of the production of security documents. More than three laser units can of course be used if necessary.

In the particular example of fig. 5, and considering that the cutting operation is performed on sheets that are being transported (as schematically illustrated by the arrow in Fig. 5), the cutting operations of the two adjacent bands of sheet material 200 are preferably carried carried out by each laser unit in a staggered manner, transversely to the direction of the leaf displacement. A first cutting operation is thus carried out in a first location (and at a first point in time) on a first of the two bands 200 as schematically illustrated by the line A in fig. 5, while a second cutting operation is performed at a second location (and at a second point in time) on the other of the two bands 200 as illustrated schematically by line B in fig. 5 (see also fig. 7). The laser beam produced by each laser unit 500 is properly diverted to each cutting position A, B and with the appropriate timing to carry out the required cutting operations of the two bands at the appropriate locations with respect to the sheet being is trying. It will of course be understood that, while fig. 5 (and fig. 7) shows that the laser beam of each laser unit 500 is diverted to two locations that are staggered with respect to each other, this is performed according to a timing such that the resulting locations in which the bands 200 are actually cut with with respect to the sheets S correspond to the desired locations where the bands are to be cut (for example cut lines C1 and C2 in fig. 2). The timing of the laser beam will basically depend on the speed at which the S sheets are being transported.

Fig. 5 further illustrates a possible configuration of the first suction unit 550 according to the invention. In order to ensure proper evacuation of the parts of the sheets of sheet material 200 that are not to remain on the sheets (whose parts correspond, in the example of fig. 2, to the parts of the bands located between cutting lines C1 and C2), the evacuation is carried out by direct aspiration of the remaining parts at least in a first position located downstream and close to the cutting positions A, B where the Continuous bands of sheet material 200 are laser cut.

It will be appreciated that such direct aspiration of the remaining parts contrasts with the solution described in European Patent Application No. 07103051.4 and in International Application No. PCT / IB2008 / 050626 in the context of a mechanical cutting system in which the remaining parts are first transported by a cylinder in front of a suction unit before actually being evacuated by aspiration (therefore such a previous solution does not provide a direct aspiration of the parts leftovers from a position located downstream and close to the location where the cutting operation is carried out as defined in the attached claims).

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To this end, the first suction unit 550 comprises a plurality of suction heads (two of them being designated by reference numbers 555a and 555b in Fig. 5) arranged next to the surface of the sheets S which are transported for Carrying out the remaining parts of the sheets of sheet material 200 in the downstream positions and close to the cutting positions A, B mentioned above. In the example of fig. 5, the suction heads 555a, 555b are consequently arranged in a staggered manner transversely to the direction of travel of the sheets S. Such a staggered arrangement is more clearly illustrated in the schematic top view of fig. 7. Each suction head 555a, 555b is conveniently coupled to the suction unit 550 by a corresponding flexible hose 551 as illustrated in fig. 5.

As many suction heads can be provided as bands of sheet material 200 are applied on the sheets S, ie a suction head for each continuous band of sheet material 200 applied on the sheets S (for example, five suction heads would be required in the example illustrated in Figs. 2 and 3). Alternatively, a suction head can be used to cooperate with more than one strip of sheet material 200.

The suction heads 555a, 555b can be advantageously mounted on support rails (not illustrated), especially in such a way in each position of each suction head 555a, 555b can be adjusted along and / or transversely to the direction of travel of the leaves S.

Figs. 6a and 6b are schematic side and bottom views, respectively, of a preferred suction head arrangement. As shown in these figures, each suction head 555a, 555b preferably comprises a suction opening 556 for aspirating the remaining parts (designated by reference number 205 in fig. 6a) of sheet material 200 to be evacuated and at least one suction support part 557 designed to rest against the surface of the sheets S in a position not covered by the sheets of sheet material 200. As illustrated in the bottom view of fig. 6b, two such support parts 557 mounted on the distal end of the suction head 555a, 555b are provided on each side of the location where the web of sheet material 200 is conducted.

The purpose of the support part or parts 557 is to provide a support against which the surface of the sheets S can be supported so as to prevent the sheets S from being sucked into the suction opening 556 and maximizing evacuation efficiency. Since the support part or parts 557 can make contact with the surface of the sheets S, it is convenient to use a low friction material to make said part or parts 557 so as to prevent defects from occurring on the sheets S as a result of friction or abrasion.

Fig. 8 is a schematic side view of another embodiment of a suction system that can be used in the context of the invention. The suction system comprises the first suction unit 550 with its plurality of suction heads 555a, 555b connected thereto by connection hoses 551, whose first suction unit 550 is located in a first location, upstream, with respect to the direction of travel of the blades S, as well as a second suction unit 560 arranged in a second position downstream of the first position of the first suction unit (in fig. 8, it will be understood that the sheets S move from right to left). This second suction unit 560 is used to evacuate excess parts 205 of the sheets of sheet material 200 that may not have been evacuated by the first suction unit. This second suction unit 560 can be advantageously designed in the manner of a simple suction tube arranged above and transversely to the direction of travel of the sheets S with suction openings located on the lower side thereof. As illustrated, the second suction unit 560 can be operatively coupled to the first suction unit 550, for example through a connection hose 561.

According to an alternative embodiment of the invention, the continuous bands of sheet material 200 could be cut in a plurality of locations along the length of the sheet material, such that a plurality of different parts of sheet material 200 * they are allowed to remain in each column of prints P on the sheets, as for example illustrated in fig. 9. This is useful in case it is desired to avoid the sheet material 200 * extending over the total height of each print P, and being limited only to a small region surrounding the windows 100. It will be appreciated that this would require a greater number of sheet cutting operations. This could easily be done by properly using the laser cutting unit a plurality of times per sheet.

In this case, the operating parameters of the laser cutting unit must be selected in such a way that they exclusively cut the sheet material 200 and do not mark the underlying surface of the S sheets.

In order to produce the result of fig. 9, the cutting operations could be carried out on the total height of the continuous web of sheet material 200 as illustrated in fig. 10, thereby creating an alternative succession of parts 200 * that have to remain on the sheets S and leftover parts 205 that are to be evacuated.

In the context of the present invention, the cutting is preferably carried out in positions where the adhesive layer has not been activated, preferably in the immediate proximity of the portions of sheet material that have

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of staying on the leaves. Although peripheral parts of the sheet material do not have to adhere to the sheets after the application process in such a case, their dimensions can be minimized. In addition, it is common practice to subject the sheets after application of the sheet material to an "intaglio" or chalcography printing process, especially for the purpose of overprinting the sheet material. As a result of the "intaglio" printing, the peripheral parts of the sheet material are made to adhere to the sheets due to the combined effect of temperature and pressure inherent in the "intaglio" printing.

Various modifications and / or improvements can be made in the embodiments described above without departing from the scope of the invention as defined by the appended claims.

In particular it will be appreciated that, although the invention is preferably applied with a view to cover windows cut in the sheets, the invention is equally applicable to any other situation in which it is desired to apply sheet material on the sheets by stratification, instead of by hot foil stamping techniques. In particular, the invention could also be applied in the context of reinforcing regions of reduced thickness, as described in WO 2004/024464 A1.

In addition, a device (not illustrated) could be provided to verify that the remaining portions 205 of the sheet material 200 have been properly evacuated. This could be done using a simple light emitting device directed towards the surface of the sheets S at the location where the sheet material 200 is applied and a photoreceptor to check a reflection point of the light beam produced by the emitting device of light. The device could alternatively comprise a camera to take a complete picture of a part of the location of the sheets S in which the sheet material 200 is applied and an image processing system to detect the presence or absence of the sheet material 200 .

Another refinement may consist of providing means for checking the passage of an anterior and / or posterior edge of the sheets S and adjusting the operation of the laser cutting unit 5 *, 500 depending on the passage of said edge. Such means may include a device for generating a beam of light perpendicular to the plane in which the sheets S are transported and detection means for monitoring a reflection point of the beam of light generated by said device on the surface of the sheets S. Alternatively , a photoreceptor could be provided on the other side of the sheets in order to detect the interruption of the light beam caused by the passage of the S sheets. The detection of the passage of the leading and / or trailing edge of the S-sheets can be used to correct the timing of the laser cutting unit and ensure that the laser beams are generated at the appropriate instants. The detection of the passage of both the trailing edge of a preceding sheet and the leading edge of a subsequent sheet can provide an indication of the actual distance between two successive S sheets.

Finally, it may be advantageous to provide an inspection system downstream of the cutting unit to inspect the quality of the sheets and detect defects in the sheets, such as improperly cutting sheet material and / or leftover parts of sheet material They stick to the sheets, as may be the case.