WO2015079341A1

WO2015079341A1 - Apparatus to apply glue to paper blanks designed for covering paper or cardboard boxes

Info

Publication number: WO2015079341A1
Application number: PCT/IB2014/065325
Authority: WO
Inventors: Mauro Mazzinghi; Pablo BARONI
Original assignee: Emmeci S.P.A.
Priority date: 2013-11-29
Filing date: 2014-10-15
Publication date: 2015-06-04
Also published as: ITBO20130660A1

Abstract

Described is an apparatus (100) for gluing paper blanks (1) designed to cover paper or cardboard boxes, comprising a conveyor belt (6) defining a conveying surface for moving blanks (1) positioned thereon in a feeding direction (A), gluing means configured for distributing glue on at least one portion of an upper face of the blanks, at least one tank (19, 26b) of PSA glue and at least one gluing station (7, 8) having at least one dispensing nozzle (18, 27) connected to the tank (19, 26b) and positioned above the conveyor belt (6) close to it, for selectively dispensing high temperature PSA glue, according to a predetermined pattern, on the upper face of the blanks (1) positioned on the belt (6) coplanar with the conveying surface.

Description

DESCRIPTION

APPARATUS TO APPLY GLUE TO PAPER BLANKS DESIGNED FOR COVERING PAPER OR CARDBOARD BOXES.

Technical field

This invention relates to an apparatus and a method to apply glue to paper blanks designed to cover cardboard boxes. Background art

In the field of lines for the production of covered paper or cardboard boxes, prior art teaches the use of covering machines which receive the formed boxes and sheets of pre-glued paper blanks and apply these covering blanks to the outer surfaces and, in part, to the inner surfaces of corresponding boxes.

For this reason, the lines for the production of covered cardboard boxes also comprise apparatus for gluing the paper blanks designed for covering the cardboard boxes.

The gluing apparatus is generally configured for distributing a layer of liquid glue on the entire surface of one of the two faces of the covering blank.

An example of the gluing machine is described in patent document IT1388513 in the name of the same Applicant.

This gluing apparatus comprises a rotary gluing roller, covered with a film of liquid glue distributed hot on the roller; the gluing roller interacts with the blank to transfer a layer of glue on the upper face of the blank.

However, this gluing apparatus has certain drawbacks and limitations. Firstly, the box covered with a blank glued with this gluing apparatus is rigid to touch.

On the contrary, the covered boxes should be rendered soft to touch, giving the lateral and base walls of the boxes a "cushioning effect".

Moreover, when the box covered with a blank glued with this gluing apparatus is handled, it tends to make a crinkly noise, that is, annoying sounds.

Another example on an apparatus for applying glue to paper blanks is disclosed in patent application US2003/084846A1 . However, this apparatus is not precise and reliable, because it entails the risk to undesirably attach glue to portions of the blank that are not meant to be glued.

Disclosure of the invention

The aim of this invention is to provide an apparatus and a method for applying glue to paper blanks designed for covering paper or cardboard boxes which overcome the above-mentioned drawbacks of the prior art. More specifically, the aim of this invention is to provide an apparatus and a method for applying glue to paper blanks designed for covering cardboard boxes which allow covered boxes to be made which are particularly soft to touch.

Moreover, the aim of this invention is to provide an apparatus and a method for applying glue to paper blanks designed for covering cardboard boxes which allow covered boxes to be made which do not make a crinkling noise when handled.

A further aim of this invention is to provide an apparatus and a method to apply glue to paper blanks designed to cover cardboard boxes which are particularly reliable and guarantee a high quality of all the boxes produced. A further aim of this invention is to provide an apparatus and a method to apply glue to paper blanks designed to cover cardboard boxes which allow a high degree of automation and production efficiency.

These aims are fully achieved by the apparatus and by the method according to the invention, as characterized in the appended claims.

The according to this invention is an apparatus for applying glue to paper blanks designed for covering paper or cardboard boxes, in a line for the production of covered boxes. In general, the line comprises: a machine for forming boxes, a covering machine, for covering the boxes with pre-glued blanks, the gluing apparatus according to this invention and a placing device.

Operatively, the gluing apparatus feeds to the placing device a succession of pre-glued blanks positioned on a flat surface; the machine for forming boxes feeds to the placing device a succession of boxes; the placing device couples each box to a corresponding pre-glued blank, placing the box with its base on a corresponding base of the pre-glued box; the assembly formed by the pre-glued blank and by the corresponding box coupled with it is fed to the covering machine, which provides the covered box at the outlet.

The gluing apparatus comprises a conveyor belt defining a conveying surface for moving blanks positioned thereon in a feeding direction. Moreover, the gluing apparatus comprises gluing means configured for distributing glue on the upper face of the blanks.

According to this invention, the glue used by the gluing apparatus is PSA glue (Pressure Sensitive Adhesive); more specifically, the glue used by the gluing apparatus is of the synthetic type, not an animal-based glue.

This avoids the crinkling noise of the covered box when touched.

Moreover, according to this invention, the gluing apparatus comprises at least one gluing station equipped with at least one dispensing nozzle. The dispensing nozzle is connected to the tank for supplying PSA glue.

The at least one dispensing nozzle is positioned above the conveyor belt close to the belt, for dispensing the PSA glue on a blank positioned on a portion of the conveyor belt below the dispensing nozzle.

The dispensing nozzle is configured for dispensing the PSA glue hot, that is, at a high temperature (for example, approximately 180°C).

This configuration prevents the glue (which is particularly viscous) from causing problems during dispensing.

Moreover, the dispensing nozzle is configured for dispensing the glue on a limited portion of the upper face of the blank, according to a predetermined pattern.

This allows the covered box to generate a cushioning effect when touched, that is, a feeling of softness.

It should be noted that the predetermined pattern of glue on the blank comprises stretches of glue positioned longitudinally (relative to a direction defined by a pair of parallel sides of the base of the blank, corresponding to the direction of movement of the blanks along the conveyor belt) and other stretches positioned transversely to the longitudinal direction.

For this purpose, preferably, there is at least one dispensing nozzle elongate along the transversal direction, to release strips of glue positioned transversely.

Preferably, the dispensing nozzle comprises a shutter (preferably blade- shaped) to interrupt the dispensing of the glue (taking into consideration that the relative movement between blank and dispensing nozzle is along the longitudinal direction).

The shutter is blade-shaped, defining indentations, in such a way that, in a closed position of the shutter, limited portions of the nozzle remain selectively open. This would allow longitudinal stretches to be also made with the same nozzle.

In this case, when changing to a different size of blank, it would normally be necessary to replace the shutter with another one having a different shape, suitable for the new size.

Alternatively, the apparatus comprises a first and a second distinct gluing station spaced along the longitudinal direction; the first gluing station dispensing transversal strips of glue and the second gluing station dispensing longitudinal strips of glue.

In that case, preferably, the second gluing station has a plurality of nozzles transversely movable independently from each other.

This simplifies the dispensing nozzle of the first gluing station and facilitates the size changeover.

Preferably, the at least one dispensing nozzle is movable vertically, away from and towards the conveyor belt. This vertical movement is controlled by an actuator synchronised with the movement of the conveyor belt.

This prevents the nozzle from accidentally dirtying the conveyor belt with glue.

According to another aspect of this invention, the apparatus preferably comprises at least one sensor positioned upstream of the dispensing nozzles, to check a positioning of the blanks fed from the belt towards the dispensing nozzles, relative to a spatial reference system (for example, a reference integral with one of the dispensing nozzles, or with the dispensing nozzle, if there is only one).

Preferably, the apparatus comprises at least one photocell (preferably two or more photocells), defining the sensor.

A control unit, connected to the sensor and to the nozzles, is configured for deactivating the dispensing nozzles in response to a detection of an incorrect positioning of a sheet relative to the nozzles.

This prevents the nozzle from dirtying the conveyor belt with glue in the case of an incorrect positioning of a sheet blank. In this way, the apparatus is particularly reliable and guarantees products with a high quality finish.

Preferably, the control unit is programmed to command the conveyor belt to move forward to feed the sheet blank below the gluing stations with the dispensing nozzles deactivated, up to an expelling area (for example, a drawer), in which the blank is positioned, for its re-use; that is, in response to the detection of an incorrect positioning of the blank.

Preferably, the control unit, which controls the conveyor belt, is connected to sensors designed to detect a position of the sheet on the belt (preferably, the sensors are associated with a structure supporting the dispensing nozzles) and it is programmed to perform a succession of stops of the conveyor belt, alternated with corresponding forward movements of the conveyor belt.

The stopping of the belt gives time to the placing device (positioned downstream of the gluing apparatus) to couple a box leaving the machine for forming boxes with a corresponding pre-glued blank.

Preferably, the control unit is programmed for stopping the belt when the portions of belt positioned above the dispensing nozzles are free of blanks.

Moreover, the control unit is programmed for moving the conveyor belt at a constant speed.

This ensures that the glue is distributed by the dispensing nozzles on the belts when the belts travel at a constant speed, preventing glue from being dispensed on the belt when it decelerates or accelerates. This makes the apparatus particularly precise, allowing glue to be deposited in a particularly uniform manner.

This effect is achieved thanks to the fact that the pauses of the belt are performed when the blanks are at a certain distance (along the longitudinal direction of feed) from the nozzles; in effect, immediately after the stops, the conveyor belt (and, therefore, also the blanks positioned on it) must accelerate.

Brief description of drawings

These and other features will become more apparent from the following detailed description of a preferred, non-limiting embodiment of the invention, with reference to the accompanying drawings, in which:

- Figure 1 shows a top plan view of an open covering sheet for boxes equipped with areas treated with glue using the gluing machine according to this invention;

- Figure 2 shows a schematic top plan view with some parts cut away of a part of a line for making covered boxes wherein the gluing machine according to this invention is inserted;

- Figure 3 is a perspective view with some parts cut away in order to better illustrate others of the gluing machine according to this invention;

- Figure 4 is a side view with some parts cut away to better illustrate others of the gluing machine of Figure 3.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, and with reference in particular to Figure 1 , the gluing machine 100 according to this invention is used on lines for the production of cardboard boxes covered with sheets of paper.

More specifically, the gluing machine 100 is used for distributing portions or stretches of glue on covering sheets 1 in the form of open paper blanks designed to then cover boxes in stations or machines positioned downstream of the gluing machine.

It should be noted that the structure of the sheet 1 shown in the accompanying drawings is merely an example and does not limit the scope of the invention.

As mentioned, the covering sheet 1 is made from a blank, preferably paper, defining a plurality of wings or sides connected to one another each of which can face and be coupled with respective walls of the box (not illustrated).

In the specific case, each side of the blank 1 surrounds both the faces (inside and outside) of the wall of the box.

More specifically, the blank 1 in the flat configuration comprises four wings or sides 2 and 3 and four flaps 4, 5.

The four sides are pre-folded to form an internal panel 2a and 3a (connected to the central base 1 a of the blank 1 for receiving the bottom of the box) and an external panel 2b, 3b.

The four flaps 4, 5 define a partial extension of two of the sides 2 of the blank 1 (in this case the sides 2 for covering the longest side walls) so that the covering is complete and continuous on the walls of the box.

The gluing machine 100 comprises a conveyor belt 6 which, hereafter, for simplicity, will be referred to as belt 6 for moving the blanks 1 along a feeding direction A. The gluing machine 100 comprises a first (independent) gluing station 7 positioned above the belt 6 and configured for distributing glue on the blank 1 and selectively forming on the blank 1 a first series of stretches T. It should be noted that the first series of stretches T are formed transversely to the feeding direction A from the first gluing station 7.

The machine 100 comprises a second (independent) gluing station 8 positioned above the belt 6 and downstream of the first station 7 relative to the feeding direction A.

It should be noted that this second gluing station 8 is configured for distributing glue on the blank 1 and selectively forming on the blank 1 a second series of stretches T of glue.

More specifically, the second series of stretches T formed by the second gluing station 8 are obtained parallel to the feeding direction A and do not coincide with the first series of transversal stretches T.

In light of this, the first and the second gluing stations 7 and 8 are equipped with activation and deactivation devices 9 and 10 connected to a control unit 1 1 designed to control the distribution of glue as a function of the chosen "pattern" on the blank 1 (as described in more detail below). Moreover, the machine 100 has a magazine 12 for feeding blanks 1 positioned upstream of the belt 6 and equipped with devices 13 for picking up and positioning the blank 1 on the belt 6.

The machine 100 also comprises a unit 14 for viewing and checking the position of the blank 1 on the belt 6.

This viewing unit 14 is positioned upstream of the two gluing stations 7 and 8 to detect a position of the blanks 1 relative to a predetermined spatial reference system (as described in more detail below);

The viewing unit 14 is connected to the control unit 1 1 for activating or deactivating the devices 9 and 10, depending on a detection of an incorrect position of the blank 1 relative to the spatial reference system. The viewing unit 14 can comprise a sensor.

Preferably, the unit 14 comprises at least two photocells 40, 41 . In light of this, the two photocells 40 and 41 are configured so that they are adjustable in their position.

Therefore, this viewing and checking unit 14 is connected to the control unit 1 1 which controls the devices 9 and 10 for activating and deactivating the two gluing stations 7 and 8.

Preferably, the belt 6 has a drive unit 15 controlled by the control unit 1 1 for moving or stopping the belt 6 according to the methods for programming and checking the gluing steps.

Preferably, the belt 6 is equipped with suction means 16 acting on the active branch of the belt 6 in contact with the blanks 1 : in this way, the blank 1 arriving from the magazine 12 maintains a stable and stationary position during all the relative path and in particular beneath the gluing stations 7 and 8.

In light of this, the belt 6 has the relative surface uniformly perforated to allow the suction by the suction means 16.

Preferably, the glue used in the two gluing stations 7, 8 is of the "PSA"

(pressure sensitive adhesive) type.

This glue is distributed hot, as it has a high viscosity.

In light of this, the first (independent) gluing station 7 is positioned above the belt 6 and comprises at least one glue dispensing head 17, comprising one or more dispensing nozzles 18, with a size at least equal to the transversal stretch T to be formed on the blank 1 (see Figures 2 to 4).

The dispensing head 17 is connected to a tank 19 for feeding the glue to introduce glue when requested.

The dispensing head 17 is supported by a carriage 20 connected, in cantilever fashion, to a frame 21 carrying both the two gluing stations 7 and 8 on respective arms 21 a and 21 b transversal to the feeding direction A.

The carriage 20 is equipped with means for guiding the dispensing head 17 along a vertical axis Z1 for moving the head 17 between a raised non- operating position, that is, away from the belt 6, to a lowered operating position, that is, towards the belt 6.

In other words, the above-mentioned devices 9 for activating / deactivating the first gluing station 7 determine, in sequence: lowering of the dispensing head 17 (in the presence of the blank 1 ); controlled activation of the dispensing of the glue; deactivation of the dispensing of the glue and raising of the dispensing head 17.

Preferably, the means for guiding the carriage 20 comprise a vertical plate 22 slidably supporting the carriage 20 supporting the dispensing head 17. The supporting plate 22 and the carriage 20 have a lead nut and screw coupling mechanism 23 connected to a drive unit 24 for allowing the lowering and raising movement of the dispensing head 17 along the vertical axis Z1 .

The drive unit 24 connected to the lead nut and screw unit 23 is connected to the devices 9 for activating / deactivating the first gluing station 7.

Preferably, carriage 20 and vertical plate 22 are coupled by slidable guides

25 to keep the vertical movement of the carriage 20 linear.

It should be noted that the second (independent) gluing station 8 (is supported by the frame 21 and comprises at least two independent dispensing heads 26.

Preferably (as shown in Figures 2 and 3) the second gluing station 8 comprises four independent dispensing heads 26.

More specifically, the second station 8 is supported, in cantilever fashion, on the transversal arm 21 b of the supporting frame 21 .

Each dispensing head 26 present on the second head 8 comprises a dispensing nozzle 27 connected to a corresponding independent carriage

28.

Each dispensing head 26 is connected to a tank 26b for feeding the glue to introduce glue when requested.

Each dispensing head 26 is equipped with devices for its independent movement along a vertical axis Z2 and devices for its independent translation along a horizontal axis X, that is, transversal to the direction A of feeding the blank 1.

Preferably, each dispensing head 26 has the carriage 28 connected to the vertical wall of a supporting plate 29 using a lead nut and screw coupling mechanism 30 connected to a drive unit 31 for allowing the lowering and raising movement of the dispensing head 26 along the vertical axis Z2 (defining the above-mentioned vertical movement devices).

The drive unit 31 connected to the lead nut and screw unit 30 is connected to the devices 10 for activating / deactivating the second gluing station 8. Preferably, each carriage 28 and each vertical plate 29 are coupled by slidable guides 32 to keep the vertical movement of the carriage 28 linear. Preferably, the devices for horizontal translation, in the two directions, of the dispensing heads 26 comprise a quadrangular frame 33 connected to the arm 21 b of the main frame 21 and on the opposite side to the position of the dispensing heads 26.

The frame 33 supports on each of the relative horizontal sides a first and a second superposed pair of drive units 34 from which corresponding threaded shafts 35 with a horizontal extension extend towards the inside of the frame 33 to form double pairs of threaded shafts parallel and superposed inside the frame 33.

A lead nut and screw (not illustrated) made on a protruding horizontal wall 38 of the supporting plate 29 of each of the dispensing heads 26 is coupled by screwing on each threaded shaft 35.

Therefore, the activation of the individual motor 34 moves the corresponding carriage 28 with dispensing head 26 along the horizontal axis X in the two directions.

Each motor 34 is connected to the devices 10 for activating / deactivating the second gluing station 8.

The second gluing station 8 is controlled by the activation / deactivation devices 10 according to sequences comprising:

- positioning the dispensing head 26 along a vertical axis Z2;

- lowering the individual dispensing head 26 (in the presence of the blank 1 );

- dispensing glue in a controlled manner;

- deactivating dispensing of glue;

- raising the dispensing head 26;

- repositioning in a position relative to the horizontal axis X or return to an initial position with any restarting of the controlled sequence for dispensing glue.

Preferably, the magazine 12 for feeding blanks 1 to the belt 6 comprises a unit 13 for picking up one individual blank 1 at a time from a stack of blanks 1 and releasing the blank 1 on the conveyor belt 6 (see Figure 1 ). Preferably, the unit 14 for viewing and checking the position of the blanks 1 on the belt 6 also comprises a portal 39 for passage of the blank 1 at the end of the belt 6.

The portal 39 is positioned, centred, relative to the spatial reference system which comprises an operational reference axis Y defined on the belt 6 and correlated and/or coincident with a predetermined position of the two gluing stations 7, 8.

Preferably, the spatial reference system is correlated or coincident with the position of the first gluing station 7.

The portal has two adjustable end panels 39a, 39b for guiding the positioning of the blank 1 on the belt 6.

The unit 14 also comprises at least two above-mentioned photocells 40, 41 for detecting the position of the blank 1 each positioned at a corresponding first and second gluing stations 7, 8.

It should be noted that the operational reference axis Y (in this case central relative to the width of the belt 6) is adjusted at the start of the operating cycle together with the position of the first and second gluing stations 7 and 8 using also the corresponding detection photocell 40, 41 positioned close to the two gluing stations 7, 8 and upstream of them relative to the feeding direction A.

More specifically, the photocell 40 for the first station 7 is connected to the innermost part of the inlet portal 39 for positioning itself close to the dispensing head 17.

The photocell 41 of the second gluing station 8 is directly associated with the lower part of the frame 33 supporting the devices for horizontal translation of the dispensing heads 26.

It should be noted that the position of the photocells 40, 41 allows the position of the blank 1 to be checked before interception by the dispensing heads 17 and 26 of the two gluing stations 7, 8.

It should be noted that the photocells 40, 41 are configured for sending a relative signal to the control unit 1 1 upon arrival of the blank 1 (with the belt 6 stopping for optical control).

If the signal sent to the control unit 1 1 is positive (position correct), the unit 1 1 enables the activation / deactivation devices 9 and 10 of the two gluing stations 7, 8 and activates again the belt 6 to allow the passage of the blank 1 below the first gluing station 7 which distributes the glue according to the programmed pattern.

In the successive forward movement, the blank 1 passed through the first gluing station 7 is stopped below the second photocell 41 , whilst a next blank 1 is stopped at the first photocell 40 (see positions of Figure 2).

If both the signals sent by the photocells 40 and 41 are positive (positions correct and centred) the control unit 1 1 sends the consent to both the gluing stations 7, 8 to distribute the glue and simultaneously re-activates the movement of the belt 6.

When one of the photocells 40 or 41 sends an error signal (position of blank incorrect), the control unit 1 1 prevents activation of the two gluing stations 7, 8 relative to that blank 1 .

In practice, the blank 1 is fed below the (stationary) gluing stations 7, 8 and sent to an area 42 for storage and recovery (if possible) of the blank 1 , passing beyond a placing device 45.

The placing device 45 (illustrated schematically) is configured for positioning a box (not illustrated) on the blank 1 , with a base of the box adhering to a base 1 a of the blank 1 .

With regard to the programming of the dispensing heads 17 and 26, due to the vertical movements (both the stations) and the transversal movements (second station 8) they can perform a selective and controlled distribution of the stretches of glue according to predetermined thicknesses S and lengths L.

With reference to the non-limiting example of the blank of Figure 1 , the patterns obtained are made by the dispensing head 17 of the first station 7 which lowers at the arrival of the free end of the wing 2 and then touches and distributes glue for a length L and a thickness S (less than the extension of the wing) and then rises to define the stretch T1 .

Similarly, the same lowering, distribution and raising procedure takes place at the end of the other wing 2 of the blank 1 to define the stretch T2. As well as the lowering, the distribution of glue and the raising (which also takes place in several successive steps), the second gluing station 8 positions the dispensing heads 26 at different distances from each other. More specifically, the innermost dispensing heads 26 define:

- the stretches T3, T4 alongside the stretches T1 and T2 (to form a sort of "U" on the outer wall of the wing 2, in particular on the panel 2b);

- two further stretches T5 and T6 along the edges of the top wing 2 (on the internal panel 2a) with an extension on the base 1 a of the blank 1 ; it should be noted that these two stretches are aligned with the stretches T3 and T4, but separated from them.

The outermost dispensing heads 26 define two stretches T7 and T8 along the outermost edge of the longest lateral wings 3 of the blank 1 , in particular on the external panel 3b.

It should be noted that the pattern just illustrated has been described merely by way of an example, since the operational logic of the gluing stations is programmable for different types of patterns.

It should also be noted that the first station 7 can comprise the nozzle(s)

18 equipped with a selector blade shutter (not illustrated) to distribute diversified PSA glue and it is also able to obtain the longitudinal stretches T3 and T4 of the pattern illustrated (using a nozzle with dimensions correlated with the need to distribute glue on larger surfaces).

With a suitably shaped blade shutter the PSA glue could also be distributed to form the stretches T5 and T6, again with the nozzle of the first station 7, leaving the second station 8 to only distribute glue for the stretches T7 and T8.

In short, the shutter comprises an actuator (not illustrated) which is able to move the shutter between an open position, spaced from the nozzle, and a closed position, wherein the shutter occludes at least a stretch of the nozzle in at least a part of its length.

The shutter is preferably controlled by the control unit to synchronise it with the belt.

Preferably, there can be at least two shutters which can be activated independently (and/or in succession) to occlude different stretches of the nozzle (that is, to close a gradually longer stretch of the nozzle).

In this way, it is possible, in a first occluding step, to close a first stretch of the nozzle and, in a second occluding step, to close a second stretch of the nozzle, in addition to or as an alternative to the closing of the first stretch.

This invention provides a method for gluing paper blanks 1 designed to cover paper or cardboard boxes.

The method comprises the following steps:

- moving a succession of blanks 1 on the flat conveyor belt 6, in a direction A for feeding to a placing device 45 configured for positioning a box on the blank 1 , with a base of the box adhering to a base 1 a of the blank 1 ;

- distributing glue on at least one portion of an upper face of the blanks 1 positioned on the belt 6,

According to the invention, the glue is PSA glue dispensed at a high temperature and selectively, along a predetermined path T, on a delimited portion of the upper face of the blank 1 , using at least one dispensing nozzle 18, 27 positioned above the conveyor belt 6 close to it, in at least one gluing station 7, 8.

Preferably, the method comprises a vertical movement of the dispensing nozzle 18, 27, away from and towards the conveyor belt 6, between a lowered position, for dispensing the glue, and a raised position, wherein the dispensing of glue is deactivated.

Preferably, the vertical movement of the dispensing nozzle 18, 27 is synchronised with a movement of the conveyor belt 6.

Again, preferably, the method comprises:

- detecting a position of the blanks 1 positioned on the belt 6 upstream of the gluing station 7, 8, relative to a predetermined spatial reference system;

- automatically deactivating the dispensing nozzle 18, 27, in response to a detection of an incorrect position of a blank 1 relative to the spatial reference system .

It should be noted that, in the case of detecting an incorrect position of a blank 1 relative to the spatial reference system, the conveyor belt 6 is controlled for feeding the blank 1 below the deactivated dispensing nozzle 18, 27, for placing the blank 1 in an unloading station 42 from which it can be picked up and reintroduced for feeding on the conveyor belt 6 in the correct position.

Preferably, the distribution of the glue on the blank 1 is performed in two distinct steps, in succession:

- in a first gluing step the glue is distributed in transversal strips, at right angles to the direction A of feeding;

- in a second gluing step the glue is distributed in longitudinal strips, parallel to the direction A of feeding.

In light of this, the method comprises a step of adjusting a transversal position of one or more nozzles 18, 27 designed for dispensing longitudinal strips, to prepare them for the gluing of blanks 1 of different sizes. Preferably, the first and second gluing steps are performed in a first and a second gluing station 7, 8, respectively, which are controlled independently by corresponding axes.

In light of this, the belt 6 performs a succession of pauses alternated with corresponding forward movements, wherein the pauses are performed when the nozzle 18, 27 is positioned above a free portion of belt 6, without blanks.

The paragraphs listed below, labelled with alphanumeric references, are non-limiting example modes of describing this invention.

A. An apparatus 100 to apply glue to paper blanks 1 designed for covering paper or cardboard boxes, comprising:

- a conveyor belt 6 defining a conveying surface for moving blanks 1 positioned thereon in a feeding direction A;

- gluing means configured for distributing glue on at least one portion of an upper face of the blanks 1 ,

characterised in that it also comprises a tank 19, 26b of PSA glue and at least one gluing station 7, 8 having at least one dispensing nozzle 18, 27 connected to the tank 19, 26b and positioned above the conveyor belt 6 close to it, for selectively dispensing high temperature PSA glue, according to a predetermined pattern, on the upper face of the blanks 1 positioned on the belt 6 coplanar with the conveying surface.

A1 . The apparatus of paragraph A, wherein the at least one dispensing nozzle 18, 27 is movable vertically, away from and towards the conveyor belt 6, between a lowered position, for dispensing glue, and a raised position, wherein the dispensing of glue is deactivated, wherein an actuator 24 designed for the vertical movement of the at least one dispensing nozzle 18, 27 is synchronised with a motor 15 designed for moving the conveyor belt 6.

A2. The apparatus of any of the paragraphs A or A1 , comprising:

- a viewing unit 40, 41 positioned upstream of the at least one dispensing nozzle 18, 27 for detecting a position of the blanks 1 relative to a predetermined spatial reference system;

- a control unit 1 1 connected to the viewing unit for deactivating the at least one dispensing nozzle 18, 27, depending on a detection of an incorrect position of the blank 1 relative to the spatial reference system. A3. The apparatus of paragraph A2, wherein the control unit 1 1 is connected to the conveyor belt 6 to control it, and it is programmed to control, in response to a detection of an incorrect position of a blank 1 relative to a conveyor belt 6, a continuation of the blank 1 on the conveyor belt 6, with the at least one nozzle 18, 27 deactivated, up to an unloading station in which the blank 1 is placed, to be able to recycle the blank 1 feeding it again into the apparatus 100.

A4. The apparatus of any of the paragraphs A, A1 , A2 or A3, comprising a first gluing station 7 and a second gluing station 8 spaced between each other along a direction of feeding the blanks 1 on the conveyor belt 6, wherein the first gluing station 7 comprises at least one dispensing nozzle 18 configured for placing sections of glue positioned transversely on the blank 1 , at right angles to the feeding direction, and the second gluing station 8 comprises a second plurality of dispensing nozzles 27 configured for placing sections of glue positioned longitudinally on the blank 1 , parallel to the feeding direction.

A5. The apparatus of paragraph A4, wherein the first gluing station 7 is positioned upstream of the second gluing station 8, relative to the direction A of feeding the blanks 1 on the conveyor belt 6.

A6. The apparatus of any of the paragraphs A4 or A5, wherein the dispensing nozzles 27 of the second gluing station 8 are movable transversely, relative to the direction of feeding the blanks 1 on the conveyor belt 6.

A7. The apparatus of any of the paragraphs A4, A5 or A6, comprising a first and a second drive unit 24, 31 connected to the first and the second gluing station 7, 8, respectively, and defining independent axes for controlling the dispensing nozzles 18 of the first station 7 independently from the dispensing nozzles 27 of the second station 8.

A8. The apparatus of any of the paragraphs A, A1 , A2, A3, A4, A5, A6 or A7, wherein the at least one gluing station 7, 8 comprises a photocell 40, 41 configured for detecting a presence of a blank 1 close to it, and wherein the apparatus comprises a control unit 1 1 connected to the photocell 40, 41 and to the conveyor belt 6 to control a succession of pauses of the conveyor belt 6, alternated with corresponding forward movements of the conveyor belt 6, in such a way that the banks 1 present on the conveyor belt 6 are outside the at least one gluing station 7, 8, during the pauses.

A9. The apparatus of any of the paragraphs A, A1 , A2, A3, A4, A5, A6, A7 or A8, wherein the at least one gluing station 7, 8 comprises a blade for interrupting a flow of glue through the at least one dispensing nozzle 18, 27, movable between an open position and a closed position for activating and deactivating, respectively, the dispensing nozzle 18, 27.

A10. The apparatus of any of the paragraphs A, A1 , A2, A3, A4, A5, A6, A7, A8 or A9, comprising an inlet portal 39, configured for allowing an access of the blanks 1 to the conveyor belt 6 and equipped with walls 39a, 39b movable towards and away along a direction transversal to a direction for feeding the blanks 1 on the conveyor belt 6, to adjust a gap for passage of the blanks 1 through the walls 39a, 39b.

B. A method for gluing paper blanks 1 designed for covering paper or cardboard boxes, comprising the following steps:

- moving a succession of blanks 1 on a flat conveyor belt 6, in a direction A for feeding to a placing device 45 configured for positioning a box on the blank 1 with a base of the box adhering to a base 1 a of the blank 1 ;

characterised in that the glue is PSA glue dispensed at a high temperature and selectively, along a predetermined path T, on a delimited portion of the upper face of the blank 1 , using at least one dispensing nozzle 18, 27 positioned above the conveyor belt 6 close to it, in at least one gluing station 7, 8.

B1 . The method of paragraph B, comprising a vertical movement of the at least one dispensing nozzle 18, 27, away from and towards the conveyor belt 6, between a lowered position, for dispensing the glue, and a raised position, wherein the dispensing of glue is deactivated, wherein the vertical movement of the at least one dispensing nozzle 18, 27 is synchronised with a movement of the conveyor belt 6.

B2. The method of any of the paragraphs B or B1 , comprising:

- detecting a position of the blanks 1 positioned on the belt 6 upstream of the at least one gluing station 7, 8, relative to a predetermined spatial reference system;

- automatically deactivating the at least one dispensing nozzle 18, 27, in response to a detection of an incorrect position of a blank 1 relative to the spatial reference system.

B3. The method of paragraph B2, wherein, in the case of detecting an incorrect position of a blank 1 relative to the spatial reference system, the conveyor belt 6 is controlled for feeding the blank 1 below the at least one deactivated dispensing nozzle 18, 27, for placing the blank 1 in an unloading station 42 from which it can be picked up and reintroduced for feeding on the conveyor belt 6 in the correct position.

B4. The method of any of the paragraphs B, B1 , B2, or B3, wherein the glue is distributed on the blank 1 in two distinct steps, in succession:

B5. The method of paragraph B4, comprising a step of adjusting a transversal position of one or more nozzles 18, 27 designed for dispensing the longitudinal strip, to prepare them for the gluing of blanks 1 of different sizes. B6. The method of any of the paragraphs B4 or B5, wherein the first and second gluing steps are performed in a first and a second gluing station 7, 8, respectively, which are controlled independently by corresponding axes. B7. The method of any of the paragraphs B, B1 , B2, B4, B5 or B6, wherein the belt 6 performs a succession of pauses alternated with corresponding forward movements, wherein the pauses are performed when the at least one nozzle 18, 27 is positioned above a free portion of belt 6, without blanks.

Claims

1 . An apparatus (100) to apply glue to paper blanks (1 ) designed for covering paper or cardboard boxes, comprising:

- a conveyor belt (6) defining a conveying surface for moving blanks (1 ) positioned thereon in a feeding direction (A);

- gluing means configured for distributing glue on at least one portion of an upper face of the blanks (1 ),

characterised in that it also comprises a tank (19, 26b) of PSA glue and at least one gluing station (7, 8) having at least one dispensing nozzle (18, 27) connected to the tank (19, 26b) and positioned above the conveyor belt (6) close to it, for selectively dispensing high temperature PSA glue, according to a predetermined pattern, on the upper face of the blanks (1 ) positioned on the belt (6) coplanar with the conveying surface, wherein the at least one dispensing nozzle (18, 27) is movable vertically, away from and towards the conveyor belt (6), between a lowered position, for dispensing glue, and a raised position, wherein the dispensing of glue is deactivated, wherein an actuator (24) designed for the vertical movement of the at least one dispensing nozzle (18, 27) is synchronised with a motor (15) designed for moving the conveyor belt (6).

2. The apparatus according to claim 1 , comprising:

- a viewing unit (40, 41 ) positioned upstream of the at least one dispensing nozzle (18, 27) for detecting a position of the blanks (1 ) relative to a predetermined spatial reference system;

- a control unit (1 1 ) connected to the viewing unit for deactivating the at least one dispensing nozzle (18, 27), depending on a detection of an incorrect position of the blank (1 ) relative to the spatial reference system.

3. The apparatus according to claim 2, wherein the control unit (1 1 ) is connected to the conveyor belt (6) to control it, and it is programmed to control, in response to a detection of an incorrect position of a blank (1 ) relative to a conveyor belt (6), a continuation of the blank (1 ) on the conveyor belt (6), with the at least one nozzle (18, 27) deactivated, up to an unloading station in which the blank (1 ) is placed, to be able to recycle the blank (1 ) feeding it again into the apparatus (100).

4. The apparatus according to any one of the preceding claims, comprising a first gluing station (7) and a second gluing station (8) spaced between each other along a direction of feeding the blanks (1 ) on the conveyor belt (6), wherein the first gluing station (7) comprises at least one dispensing nozzle (18) configured for placing sections of glue positioned transversely on the blank (1 ), at right angles to the feeding direction, and the second gluing station (8) comprises a second plurality of dispensing nozzles (27) configured for placing sections of glue positioned longitudinally on the blank (1 ), parallel to the feeding direction.

5. The apparatus according to claim 4, wherein the first gluing station (7) is positioned upstream of the second gluing station (8), relative to the direction (A) of feeding the blanks (1 ) on the conveyor belt (6).

6. The apparatus according to claim 4 or 5, wherein the dispensing nozzles (27) of the second gluing station (8) are movable transversely, relative to the direction of feeding the blanks (1 ) on the conveyor belt (6).

7. The apparatus according to any one of claims 4 to 6, comprising a first and a second drive unit (24, 31 ) connected to the first and the second gluing station (7, 8), respectively, and defining independent axes for controlling the dispensing nozzles (18) of the first station (7) independently from the dispensing nozzles (27) of the second station (8).

8. The apparatus according to any one of the preceding claims, wherein the at least one gluing station (7, 8) comprises a photocell (40, 41 ) configured for detecting a presence of a blank (1 ) close to it, and wherein the apparatus comprises a control unit (1 1 ) connected to the photocell (40, 41 ) and to the conveyor belt (6) to control a succession of pauses of the conveyor belt (6), alternated with corresponding forward movements of the conveyor belt (6), in such a way that the banks (1 ) present on the conveyor belt (6) are outside the at least one gluing station (7, 8), during the pauses.

9. The apparatus according to any one of the preceding claims, wherein the at least one gluing station (7, 8) comprises a blade for interrupting a flow of glue through the at least one dispensing nozzle (18, 27), movable between an open position and a closed position for activating and deactivating, respectively, the dispensing nozzle (18, 27).

10. The apparatus according to any one of the preceding claims, comprising an inlet portal (39), configured for allowing an access of the blanks (1 ) to the conveyor belt (6) and equipped with walls (39a, 39b) movable towards and away along a direction transversal to a direction for feeding the blanks (1 ) on the conveyor belt (6), to adjust a gap for passage of the blanks (1 ) through the walls (39a, 39b).

1 1 . A method for gluing paper blanks (1 ) designed for covering paper or cardboard boxes, comprising the following steps:

- moving a succession of blanks (1 ) on a flat conveyor belt (6), in a direction (A) for feeding to a placing device (45) configured for positioning a box on the blank (1 ) with a base of the box adhering to a base (1 a) of the blank (1 );

- distributing glue on at least one portion of an upper face of the blanks (1 ) positioned on the belt (6),

characterised in that the glue is PSA glue dispensed at a high temperature and selectively, along a predetermined path (T), on a delimited portion of the upper face of the blank (1 ), using at least one dispensing nozzle (18, 27) positioned above the conveyor belt (6) close to it, in at least one gluing station (7, 8), wherein the method further comprises a vertical movement of the at least one dispensing nozzle (18, 27), away from and towards the conveyor belt (6), between a lowered position, for dispensing the glue, and a raised position, wherein the dispensing of glue is deactivated, wherein the vertical movement of the at least one dispensing nozzle (18, 27) is synchronised with a movement of the conveyor belt (6).

12. The method according to claim 1 1 , comprising: - detecting a position of the blanks (1 ) positioned on the belt (6) upstream of the at least one gluing station (7, 8) , relative to a predetermined spatial reference system;

- automatically deactivating the at least one dispensing nozzle (18, 27), in response to a detection of an incorrect position of a blank (1 ) relative to the spatial reference system.

13. The method according to claim 12, wherein, in the case of detecting an incorrect position of a blank (1 ) relative to the spatial reference system, the conveyor belt (6) is controlled for feeding the blank (1 ) below the at least one deactivated dispensing nozzle (18, 27), for placing the blank (1 ) in an unloading station (42) from which it can be picked up and reintroduced for feeding on the conveyor belt (6) in the correct position.

14. The method according to any one of claims 1 1 to 13, wherein the glue is distributed on the blank (1 ) in two distinct steps, in succession: - in a first gluing step the glue is distributed in transversal strips, at right angles to the direction (A) of feeding;

- in a second gluing step the glue is distributed in longitudinal strips, parallel to the direction (A) of feeding.

15. The method according to claim 14, comprising a step of adjusting a transversal position of one or more nozzles (18, 27) designed for dispensing the longitudinal strip, to prepare them for the gluing of blanks (1 ) of different sizes.

16. The method according to claim 14 or 15, wherein the first and second gluing steps are performed in a first and a second gluing station (7, 8), respectively, which are controlled independently by corresponding axes.

17. The method according to any one of claims 1 1 to 16, wherein the belt (6) performs a succession of pauses alternated with corresponding forward movements, wherein the pauses are performed when the at least one nozzle (18, 27) is positioned above a free portion of belt (6), without blanks.