Patent Description:
The invention relates to the technical field of industrial processing of sheets of paper or cardboard for forming finely finished, quality boxes. These boxes are made from specially shaped sheets, called blanks, consisting of a base and a plurality of segments (or panels) connected to the base and foldable relative to it to make up a sidewall of the box.

As regards the shape of the blank, generally speaking the number of segments of the blank is equal to the number of sides of the base and each segment is connected to a respective side of the base. This type of blank may be generally referred to as "petalled", like a flower.

Blanks of other shapes are also used, however.

For example, the number of segments may be equal to (or greater than) the number of sides of the base, but the number of segments connected directly to the base may be less than the number of sides of the base since some of the segments may be connected to other segments.

In such a case, the blank is referred to as "H-shaped" or "T-shaped" or "cross-shaped", depending on the configuration adopted by the blank when it is laid out flat.

If the segments are greater in number than the sides of the base, some of the segments are associated with other segments and are foldable sideways to cover the same face of the sidewall of the box, each enclosing a respective vertical edge of that face.

The industrial process starting with the blank and ending with the finished box comprises two distinct steps: a step of forming the box, followed by a step of covering the box by applying a covering sheet to it.

This invention relates specifically to the step of forming the box.

The forming step in turn comprises two successive steps: a first step of folding, followed by a step of sealing or closing.

In the step of folding, the segments of the blank (which is laid out flat to start with) are folded about the perimeter of the base to form the sidewall of the box. The sidewall of the box defines as many lateral edges as there are corners of the base.

Of these vertical edges (of the vertical wall of the box), at least two are defined by a pair of adjacent lateral borders belonging to consecutive folded segments. This applies generally speaking to any type of blank.

More specifically, if the blank is of the "petalled" type, all the lateral edges are defined by corresponding pairs of adjacent lateral borders belonging to consecutive folded segments (on the other hand, if the blank is T-shaped or H-shaped, only a subset of the lateral edges is defined by corresponding pairs of adjacent lateral borders of consecutive folded segments).

In particular, box forming machines usually comprise a vertically movable die which is operatively coupled to an inner surface of the base (or of the sidewall of the box) to fold the segments of the blank by causing them to interact with fixed contact members.

When the step of folding the segments about the base is over, the above mentioned lateral edges are open and a step of connecting adjacent panels is necessary to close the lateral edges.

For this purpose, according to automatic forming machines known in the prior art, a step of sealing follows by which the open lateral edges of the box sidewall are joined (that is, closed).

As regards the step of sealing, two alternative technical solutions are essentially known.

According to a first solution (described for example in patent document.

<CIT> in the name of the same Applicant as this invention), sealing occurs by applying sealing strips (called "stay tapes") to the open lateral edges in order to close them.

More specifically, box forming machines usually comprise sealing heads having respective sealing tape dispensers and applicator elements ("pressers") designed to apply strips of sealing tape to corresponding open lateral edges of the box. The sealing heads can move towards and away from the box between a non-interference position where they are clear of the box and a sealing position where they operate on the corresponding open lateral edges to press the tapes against respective lateral edges of the box, thereby sealing them.

In the step of sealing, the function of the die is that of defining a constraining element operatively inserted snugly into the space inside the box during the action of the pressers, thereby preventing the pressers from deforming the sidewall of the box.

In a second solution (described for example in patent document <CIT> in the name of the same Applicant as this invention) hot-melt glue is distributed along the vertical edges of the sidewall of the box, in the interstices formed by the borders of the pairs of segments placed side by side. In practice, this forms a bead of glue which joins the end borders of the joined segments to form the corresponding edges of the sidewall.

The pressers are then moved forward to abut against the edges, with the further important function of cooling the glue.

The solution which involves applying the stay tapes is simple and reliable but has the disadvantage of worsening the appearance of the box because the tapes are not negligible in thickness (compared to the blank) and are therefore visible.

The solution which involves spreading hot-melt glue along the gap formed by the borders of the folded segments to form the edges of the sidewall of the box avoids the use of the stay tapes, thereby improving the aesthetic appearance of the box, but is inconvenient because it is particularly complicated (and hence relatively unreliable). The complication is due, for example, to the need to cool the glue and the difficulty of spreading the glue precisely in the interstices.

Thus, neither of the techniques described above is free of disadvantages. Moreover, it should be noted that another requirement in the sector of fine quality boxes regards the box edges, which must be sharp and well-defined, without visible signs of misshapen or rounded parts.

For this purpose, the use of special blanks is known in the prior art (for example, from patent document <CIT>). These blanks are obtained by a process which comprises trimming the sheet of paper to form V-shaped grooves.

Thus, in a blank of this type (modified), the free sides of some lateral segments (the sides that are joined to form the sidewall of the box), as well as the sides for joining the base to the segments, are bevelled to define oblique faces contained in the thickness of the blank.

In this solution, the glue is spread on all the oblique faces defined by the bevels (and thus along all the sides of the base and along the sides of the segments) when the blank is laid out flat horizontally (and thus, before the segments are folded to form the vertical edges of the box).

In this solution, there is a supporting structure configured to enable the blank to move in a feed plane along a longitudinal feed direction to convey it to a gluing station.

The glue is applied by glue heads which are movable along predetermined directions parallel to the feed plane in such a way as to spread the glue on the oblique faces.

This method has a twofold advantage: on the one hand it allows production of boxes whose sharp edges have none of the aesthetic flaws due to the stay tapes, and on the other, it avoids the complications associated with spreading hot melt glue along interstices of vertical edges. The gluing system of the special V-grooved blank described in patent document <CIT> has some limitations which make it unsuitable for use in an automatic box forming machine.

In this regard, it should be noted that a blank gluing system, in order for it to be used in an automatic forming machine, must meet not only the need for glue spreading precision but also that for high speed (so as to guarantee a high output per hour).

<CIT> discloses a method for producing blanks from cardboards.

Document <CIT> discloses a paper box manufacturing equipment comprising a gluing device, as well as a supporting structure adapted to convey a blank up to said gluing device. The supporting structure further has blank positioning means, and a blank locking means adapted to keep the blank in place in a predetermined longitudinal position.

This invention has for an aim to provide a blank gluing device for an automatic box forming machine which overcomes the above mentioned disadvantages of the prior art.

More specifically, it is aim of this disclosure to provide a blank gluing device for an automatic box forming machine which is particularly precise and suitable for use in an automatic box forming machine.

Another aim of this disclosure is to provide a blank gluing device for an automatic box forming machine which is particularly rapid.

A further aim of this disclosure is to provide a method for gluing flat blanks which is particularly precise and suitable for use in a box forming process implemented by automatic machinery.

The above mentioned aims are fully achieved by the apparatus and method according to the appended claims.

More specifically, the gluing device according to the disclosure is a gluing device for a box forming machine and is configured to apply liquid glue to a flat blank of paper or cardboard having a base and a plurality of segments connected to the base and foldable to form a box sidewall, where the free sides of the segments, designed to be joined to form the edges of the box sidewall, are bevelled to define oblique faces contained in the thickness of the segments.

According to the disclosure, the supporting structure comprises:.

This guide system, combined with the positioning means and with the locking means, allows the blank to be positioned extremely precisely and held in place while the glue dispensing nozzles are working. This ensures the glue is applied correctly and makes the device particularly precise.

It should be noted that the guides are configured to support the end portions of blank segments and, in particular, the guides are spaced from each other to define an empty space between them.

This solution makes it possible to leave the base of the blank free to be moved downwards without constraints or interference. That makes the device especially suited to be used in an automatic forming machine, allowing a particularly high processing speed to be reached. In effect, after the glue has been spread, the blank is lowered directly to fold the segments without having to move the blank sideways away from the gluing station.

Preferably, the predetermined direction of moving the at least one nozzle is perpendicular to the longitudinal blank feed direction defined by the supporting structure.

This allows the glue to be spread only along the oblique surfaces positioned transversely relative to the longitudinal blank feed direction.

This has the advantage of making the device particularly precise, since the longitudinal positioning of the blank, because it is performed by specific positioning means, is particularly precise relative to transversal positioning, since the guides must leave a minimum possibility of transversal movement (play) to allow it to move forward along the guides themselves.

Furthermore, spreading the glue only on the transversal oblique faces (and not on the longitudinal ones) saves time.

In light of this, it should be noted that the device preferably comprises a pair of nozzles which are spaced along the longitudinal direction.

This allows the speed of the device to be further increased because the entire step of spreading the glue is completed in the interval of time taken by the nozzles to move transversely across the blank.

Preferably, the pair of nozzles is positioned at a variable distance along the axis parallel to the longitudinal blank feed direction defined by the supporting structure. This makes changeover particularly easy.

In light of this, it should be noted that the positioning means, too, are provided with adjusters which make changeover of the device particularly quick and easy, as described in more detail below.

It should be noted that, for their part, the locking means are important for the precision and reliability of the device.

In effect, the locking means guarantee that while the glue is being spread the blank does not undergo deformation or bending (moving under the force of gravity outside the feed plane) which would prevent the glue from being correctly spread on the oblique faces of the edges (it should be noted that the V-shaped grooves formed on the blank weaken it and make it particularly susceptible to such deformation).

The disclosure also provides a forming machine for making boxes of paper or cardboard from flat blanks and comprising the gluing device.

The forming machine is particularly precise and fast and allows boxes to be made automatically from the special blanks (with V-shaped grooves).

Preferably, the forming machine also comprises a system for applying stay tapes to the edges of the sidewall of the box (this system being of a per se known type).

Advantageously, that makes the forming machine particularly flexible since it can make boxes from blanks of any kind.

In effect, if the blank is a special blank (with V-shaped grooves), the gluing device is enabled and the system for applying stay tapes is disabled. Vice versa, if the blank is of a traditional type (without V-shaped grooves), the gluing device is disabled and the system for applying stay tapes is enabled.

The disclosure also provides a gluing method for applying liquid glue to a flat blank of paper or cardboard having a base and a plurality of segments connected to the base and foldable to form a box sidewall, where the free sides of the segments, designed to be joined to form the edges of the box sidewall, are bevelled to define oblique faces contained in the thickness of the segments.

According to the disclosure, the method comprises the following steps:.

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

The numeral <NUM> in the drawings denotes a box forming machine according to this invention.

The forming machine <NUM> is a machine for forming boxes of paper or cardboard from flat blanks <NUM> (of paper or cardboard), having a base <NUM> and a plurality of segments <NUM> connected to the base <NUM> and foldable to form a box sidewall.

The forming machine <NUM> is set up to use special blanks <NUM> having the features described below (illustrated in <FIG>).

The free sides of the segments <NUM>, which are intended to be joined to form the sidewall of the box, are bevelled to define oblique faces <NUM> contained in the thickness of the segments <NUM>.

Generally speaking, this special blank (hereinafter referred to simply as "blank", for short) is made from a sheet on whose top face V-shaped grooves are formed (for example by cutting) along straight trajectories comprising (defined by) the sides of the base <NUM>.

Preferably, therefore, the sides of the base <NUM> and the sides of the segments <NUM> connected to corresponding sides of the base <NUM> are also bevelled to define oblique faces contained in the thickness of the base <NUM> and of the segments <NUM>, respectively.

The numeral <NUM> in <FIG> denotes the oblique faces on the sides of the base <NUM>.

Preferably, these oblique faces <NUM>, <NUM> are inclined at an angle of approximately <NUM> degrees to the plane defined by the blank <NUM>. That way, when the segments <NUM> are folded relative to the base to form a right angle, the lateral oblique faces <NUM> of the segments <NUM> and the oblique faces <NUM> of the base <NUM> come into contact with each other.

The forming machine <NUM> (illustrated schematically in <FIG>) comprises:.

The manipulating means comprise a die <NUM> shaped to snugly occupy the inside of the box and connected to a motor-driven shaft <NUM> which moves it along a predetermined vertical axis (according to a substantially known method).

Also, preferably, the forming machine <NUM> comprises stay tapes (not illustrated, but of a per se known type) coupled to the presser elements <NUM> to allow strips of the stay tapes to be applied to the vertical edges of the box sidewall in order to seal them (according to a method known in the trade, applicable to any type of blank and not only to the above described special blanks, that is, blanks with V-shaped grooves).

According to the disclosure, the forming machine <NUM> comprises a gluing device <NUM> for applying glue (liquid glue, preferably of the hot-melt type) on the (special) blanks <NUM>.

Indeed, the disclosure has for an object the gluing device <NUM> as well as the forming machine <NUM> which incorporates the device <NUM>.

In effect, the device is designed to be connected to a traditional forming machine <NUM> in order to modify it to make it particularly suitable for forming boxes from the (special) blanks <NUM>.

The description below will therefore focus on the gluing device <NUM>.

The supporting structure <NUM> is illustrated in detail in <FIG>, <FIG> and <FIG>.

The supporting structure <NUM> comprises a first and a second guide <NUM> positioned longitudinally in the feed plane of the blank <NUM> to define the longitudinal direction of movement of the blanks <NUM>.

Each guide <NUM> is shaped in such a way as to prevent transversal movements of the blank <NUM> (that is, movements perpendicular to the longitudinal direction of movement and contained in the feed plane).

Also, each guide <NUM> is shaped to slidably support a portion of the blank <NUM>. More specifically, the guide <NUM> is shaped in such a way as to slidably support a lateral end portion of one of the segments <NUM> of the blank <NUM>.

In the example illustrated, each guide <NUM> has an L-shaped or C-shaped profile, the guides <NUM> being opposed to one another.

More specifically, in the example illustrated, each guide <NUM> comprises a ledge <NUM>, which lies in the feed plane, for slidably supporting the lateral portions of the blank <NUM>.

More precisely, it should be noted that the feed plane (that is, the plane in which the blank <NUM> lies) is defined by the large surfaces of the ledges <NUM> on which the blank <NUM> itself rests.

Further, each guide <NUM> comprises a wall <NUM> perpendicular to the ledge <NUM> (and to the feed plane).

Thus, the walls <NUM> of the guides <NUM> laterally delimit a slideway for the blank <NUM>, preventing transversal movements of the latter.

The first and second guides <NUM> are spaced from each other to define an empty space between them.

The supporting structure <NUM> also comprises brackets (not illustrated) for connecting the guides <NUM> to a frame of the machine <NUM>. Alternatively, the guides <NUM> (and, more generally speaking, the supporting structure <NUM>) may be fastened to any base in a fixed position relative to the frame of the forming machine <NUM>.

The forming machine <NUM> (that is, the gluing device <NUM>) also comprises a pushing element (not illustrated, of per se known type, consisting for example of a finger connected to an actuator) movable longitudinally between the guides <NUM> to move the blank forward along the guides <NUM> towards the gluing station.

Thus, the supporting structure <NUM>, together with the pushing element, constitutes a conveyor adapted to feed the blanks <NUM> to the gluing station.

Further, according to the disclosure, the supporting structure <NUM> comprises positioning means <NUM> operating on the blank <NUM> to move it to a predetermined longitudinal position in the gluing station.

It should be noted that the predetermined longitudinal position is, more specifically, a position of alignment with a predetermined reference axis perpendicular to the feed plane and consisting preferably of the axis (vertical) along which the die <NUM> moves.

In the preferred embodiment illustrated, the positioning means <NUM> comprise at least a first pusher <NUM> configured to interact with a corresponding border of one of the segments <NUM> of the blank resting on the (ledges <NUM> of the) guides <NUM>, the blank being positioned transversely, in order to impart a controlled movement to the blank <NUM> along the longitudinal direction.

Preferably, the positioning means <NUM> comprise at least one second pusher <NUM> positioned at a predetermined distance from the first pusher <NUM> along the longitudinal direction, the first pusher <NUM> and the second pusher <NUM> operating on corresponding borders of segments <NUM> of the blank <NUM> (resting on the ledges <NUM> of the guides <NUM>) from longitudinally opposite sides, that is, in such a way that the first pusher <NUM> and the second pusher <NUM> are positioned downstream and upstream of the blank <NUM> positioned in the gluing station, relative to the advancing direction of the blank along the longitudinal direction.

In practice, the blank <NUM> positioned in the gluing station is longitudinally interposed between the first pusher <NUM> and the second pusher <NUM>.

Preferably, the positioning means <NUM> of the supporting structure <NUM> comprise a pair of first pushers <NUM> and a pair of second pushers <NUM>.

In practice, in the preferred embodiment illustrated, the positioning means <NUM> comprise a total of four pushers operating on both the segments <NUM> (transversely opposed and resting on the ledges <NUM> of the guides <NUM>), on the opposite transversal sides of the selfsame segments <NUM>.

The first pushers <NUM> are preferably associated with the guides <NUM>.

The second pushers <NUM>, too, are preferably associated with the guides <NUM>. Thus, the pushers <NUM> and <NUM> are configured to interact with corresponding transversely positioned borders of the blank segments <NUM> resting on (the ledges <NUM> of the) guide <NUM>.

The pushers <NUM> and <NUM> (consisting, for example, of the pistons of corresponding cylinder/piston assemblies) are movable longitudinally between an extended position where they abut against the borders of the blank <NUM> when the blank <NUM> is at the predetermined longitudinal position and a withdrawn position where they are away from the blank <NUM>.

The pushers <NUM> and <NUM> are shown in the extended position in <FIG> and in the withdrawn position in <FIG>.

Preferably, the ends of the first pushers <NUM>, that is the pushers <NUM> positioned downstream, define flat portions <NUM> positioned perpendicularly to the feed plane (to provide a better grip on the borders of the segments <NUM>).

Preferably, the second pushers <NUM>, that is, the pushers <NUM> located upstream (of the blank <NUM> positioned in the gluing station), have teeth <NUM> (pivotally connected to the end of a stem, that is, of a piston, of a corresponding second pusher <NUM>) which are movable between a first operating position where they are spaced from the feed plane of the blank <NUM> so as not to interfere with blank feed, and a second operating position where they intersect the feed plane so as to define an abutment for the transversal border of the blank <NUM>.

Preferably, the teeth <NUM> of the second pushers <NUM> oscillate about respective transversal axes.

Preferably, the teeth <NUM> of the second pushers <NUM> oscillate freely. That way, the blank <NUM> itself, as it advances along the longitudinal direction towards the gluing station, moves the teeth <NUM> to the first operating position. Then, once the blank <NUM> has passed them, the teeth <NUM> return to the second operating position by gravity (the second operating position being a position of equilibrium into which the teeth <NUM> tend to move when no external forces are applied to them).

The second pushers <NUM> are also equipped with stops <NUM>. The teeth <NUM> abut against the stops <NUM> when they are at the second operating position. The stops <NUM> are configured to prevent the teeth <NUM> from rotating in response to a pushing action (for example from the blank <NUM>) backwards away from the gluing station along the longitudinal direction.

Alternatively, instead of the stops <NUM>, any other suitable system may be used to allow the teeth <NUM> to move from the second operating position to the first only when the blank <NUM> passes as it advances towards the gluing station, preventing this movement in response to a force tending to move the blank backwards in the opposite direction.

Preferably, the pushers <NUM> and <NUM> are connected to the guides <NUM>.

Preferably, the pushers <NUM> and <NUM> are slidably coupled to the guides <NUM> (for example, they are mounted on sliders <NUM> that run on rails <NUM> defined by the guides <NUM>).

The positioning means <NUM> preferably also comprise locking/unlocking means (for example brakes which can be operated by levers <NUM>).

This makes it possible to adjust the position of the pushers (of the first pushers <NUM> and, by means of a similar system, also of the second pushers <NUM>) longitudinally and to decide the exact point they must be fixed to on the guides <NUM>.

This adjustment system has two functions.

A first function is that of aligning the positioning means <NUM> relative to a vertical axis (that is, perpendicular to the feed plane which the guides <NUM> lie in) of the forming machine <NUM>, for example, relative to the vertical axis of movement of the die <NUM>.

A second function is that of adjusting the distance (along the longitudinal direction) between the first pushers <NUM> and the second pushers <NUM>, in order to adapt the positioning means <NUM> to different box sizes.

Preferably, the pushers <NUM> and <NUM> are pneumatic.

Preferably, the pushers <NUM> and <NUM> have a predetermined stroke (length of movement of the stem, or piston, relative to the cylinder).

The predetermined stroke (fixed) is determined during a preliminary step of calibrating the gluing device <NUM> (described in detail below).

Further, according to the invention, the supporting structure <NUM> comprises locking means <NUM> operating on the blank <NUM> for holding the blank in place so it is in the same plane as the feed plane while it is in the predetermined longitudinal position (determined by the positioning means <NUM>).

The locking means <NUM> are preferably associated with the guides <NUM>.

The locking means <NUM> define jaws <NUM> which are movable between an open position of non-interference with the blank <NUM>, and a closed position, where they operate on the blank segments <NUM> resting on the guides <NUM> in order to keep them in the feed plane.

More specifically, in the example illustrated, the jaws of the locking means <NUM> are configured to interact with the ledges <NUM> so as to press the lateral end portions (of the segments <NUM>) of the blank <NUM> (these end portions being operatively interposed between the jaws <NUM> and the ledges).

The jaws <NUM> are connected to corresponding actuators <NUM>. The actuators <NUM> (for example, pneumatic) are preferably associated with the guides <NUM>.

As regards the gluing nozzles <NUM> and the supporting and movement system <NUM> for the nozzles <NUM>, attention is drawn to the following (with reference in particular to <FIG>, <FIG> and <FIG>).

In one variant embodiment not illustrated, the locking means <NUM> are defined by a plate positioned in a zone under the blank <NUM> and movable vertically, acting in conjunction with the die <NUM> or other contact member (smaller than the die <NUM>) positioned in the zone above the blank <NUM> and movable vertically.

In this solution, the plate and the contact member can be moved towards each other in such a way as to hold in between them a central portion of the base <NUM> of the blank <NUM>.

The supporting system <NUM> for the nozzles <NUM> preferably comprises a bracket <NUM> having a first end which can be anchored to the frame of the forming machine <NUM> or to the supporting structure <NUM>.

The bracket <NUM> is positioned relative to the guides <NUM> in such a way that it rises up (substantially perpendicularly) from the feed plane.

A rod <NUM> is movably connected in cantilever fashion to a second end <NUM> of the bracket <NUM>. The rod <NUM> is connected to the bracket <NUM> movably so it can be translated in a predetermined direction parallel to the feed plane (that is, to the plane in which blank <NUM> lies).

In the preferred embodiment (illustrated), the supporting and movement system <NUM> for the nozzles <NUM> is positioned in such a way that the rod <NUM> is movable along a transversal direction, that is, a direction perpendicular to the longitudinal direction of movement of the blank <NUM> along the guides <NUM>.

Preferably, the supporting and movement system <NUM> for the nozzles <NUM> is positioned laterally of one of the two guides <NUM>.

The rod <NUM> is movable in both directions.

More specifically, the rod <NUM> is slidably coupled to a guide block <NUM> fixed to the bracket <NUM>.

Preferably, the rod <NUM> is driven by an electric motor <NUM>. Preferably, the rod <NUM> defines a rack coupled to the electric motor <NUM> through the agency of a pinion.

The nozzles <NUM> (the at least one nozzle <NUM>) are connected to the free end of the rod <NUM>.

The nozzles (the at least one nozzle) <NUM> are inclined with respect to the feed plane (at angles of approximately <NUM> degrees); preferably, the nozzles are directed in such a way as to converge (in the glue emitting direction). Hence, the nozzle <NUM> is inclined with respect to the feed plane in such a way as to spread the glue perpendicularly (substantially) perpendicularly to the corresponding oblique face <NUM> (of the bevelled edge). The nozzles <NUM> dispense liquid, hot-melt glue of a per se known type.

Preferably, the nozzles <NUM> are adjustably mounted on the rod <NUM> so that their angle of inclination can be varied.

Preferably, the nozzles <NUM> are adjustably mounted on the rod <NUM> so that the distance between the nozzles <NUM> themselves can be varied.

In the example illustrated, there is a bar <NUM> fixed to the free end of the rod <NUM> and transversely thereto (so that the bar <NUM> is positioned along the longitudinal direction). The nozzles <NUM> can be anchored along slots <NUM> defined by the bar <NUM> and extending longitudinally.

The fact that the nozzles <NUM> are mounted with a variable spacing along an axis parallel to the longitudinal direction of blank <NUM> feed allows the gluing device <NUM> to be adapted to blanks <NUM> of different sizes.

Operatively, the gluing device <NUM> according to the invention works as follows.

A blank <NUM> (of the type shown in <FIG>) is coupled to the guides <NUM> in such a way that lateral end portions of two segments <NUM> of it (on laterally opposite sides) rest on the (ledges <NUM> of the) guides <NUM>.

The blank <NUM> is fed forward towards a gluing station until it is interposed between the first pushers <NUM> and the second pushers <NUM>. As it moves, the blank (or more specifically, the segments <NUM> resting on the guides <NUM>) interacts with the teeth <NUM> of the second pushers <NUM>, pushing them to a position of non-interference solely under the action of its own passing.

At this point, the four pushers (the first pushers <NUM> and the second pushers <NUM>) are moved towards the segments <NUM> of the blank <NUM> (the lateral segments <NUM> resting on the guides) until abutting (when the pushers themselves reach the end of their stroke) against the transversely positioned borders of these segments (this configuration is shown in <FIG>).

The first pushers <NUM> and the second pushers <NUM> advance towards the blank <NUM> from opposite sides (longitudinally) of the blank <NUM> itself in order to close it in the middle.

At this point, the locking means <NUM> (which up to this moment have been inactive in the position of non-interference with the blank <NUM>) are activated in order to lock the blank at the predetermined longitudinal position reached when the pushers <NUM>, <NUM> are in abutment against the blank <NUM>.

As a result of activation of the locking means <NUM> (the lateral segments <NUM> of the blank <NUM> are gripped, so that) the blank <NUM> is forced to remain in place and in the same plane as the feed plane.

At this point, the first pushers <NUM> and the second pushers <NUM> withdraw longitudinally away from the blank <NUM> and return to a position of non-interference therewith (this situation is illustrated in <FIG>).

At this point, the nozzles <NUM> are moved along the trajectories defined by the oblique faces <NUM> of the segments <NUM> and are activated to apply glue at least on a number of oblique faces <NUM> equal to half the total number of oblique faces <NUM> of the segments <NUM>, so that for each pair of oblique faces <NUM> (belonging to different segments <NUM> and) combining to form an edge of the box sidewall, at least one has glue applied to it.

Preferably, the nozzles <NUM> are moved transversely to apply glue to all of the oblique faces <NUM> which are transversely positioned, while no glue is applied to the oblique faces <NUM> which are positioned longitudinally.

Preferably, the nozzles <NUM> remain active so as to spread glue also on the oblique faces <NUM> of the base <NUM> which are positioned transversely (and which are interposed between the oblique faces <NUM> of the segments to which glue is also applied) while, preferably, no glue is applied to the oblique faces <NUM> of the base <NUM> which are positioned longitudinally.

This makes the device <NUM> particularly fast.

It should be noted that the supporting structure <NUM> is configured in such a way that the spacing of the guides <NUM> can be adjusted during initial setting up of the device <NUM>.

In light of this, the device <NUM> is preferably configured in such a way that a blank whose base <NUM> is rectangular in shape is coupled to the guides <NUM> with the long sides of the base positioned longitudinally.

Described below is the procedure (briefly mentioned above) for calibrating, that is, setting up, the positioning means <NUM>.

First of all, the blank <NUM> (of the required size for the boxes to be made) is positioned in the gluing station between the first pushers <NUM> and the second pushers <NUM>.

Next, the pushers <NUM> and <NUM> are extended (to the end of their stroke) and are moved along the guides <NUM> until the blank <NUM> is at the required longitudinal position, with the pushers <NUM> and <NUM> extended and in abutment against the lateral segments <NUM> of the blank <NUM> itself.

At this point, the pushers <NUM> and <NUM> are fixed stably to the guides <NUM> in such a way that the fixed parts of the pushers (for example, in the case of cylinder and piston assemblies, the cylinders) remain in place during the operation of the device <NUM>.

This disclosure therefore also provides a gluing method for applying liquid glue to the blank <NUM>.

Preferably, the at least one nozzle <NUM> (preferably, the pair of nozzles <NUM>) is moved only transversely to the longitudinal direction of blank <NUM> feed, so that glue is applied only to a subset of the oblique faces <NUM> defined by the bevelled edges.

Preferably, the positioning of the blank <NUM> at the predetermined longitudinal position is accomplished by moving a first pusher <NUM> and a second pusher <NUM> longitudinally in opposite directions until the selfsame pushers <NUM> and <NUM> reach an extended position where they are in abutment against corresponding borders of the blank <NUM> segments <NUM> resting on the guides (the borders being) positioned transversely to the longitudinal direction of blank <NUM> feed.

Also, preferably, before the step of moving the at least one liquid glue dispensing nozzle <NUM> and after the step of locking, the pushers <NUM> and <NUM> are moved away from each other to a withdrawn position of non-interference with the blank <NUM>.

It should be noted that the disclosure also provides a method for modifying a forming machine <NUM> to make it suitable for making boxes from special blanks (of the type described above and illustrated in <FIG>), which however does not form part of the claimed invention.

This method comprises providing a gluing device <NUM> (as described above) and installing it in a forming machine <NUM> (for example of the traditional type, equipped with stay tape applicators).

The gluing device <NUM> is installed in the forming machine <NUM> in place of the existing blank feed guides. Alternatively, the existing guides may be modified to obtain the supporting structure <NUM> described above.

Claim 1:
A gluing device (<NUM>) for a box forming machine (<NUM>) and configured to apply liquid glue to a flat blank (<NUM>) of paper or cardboard having a base (<NUM>) and a plurality of segments (<NUM>) connected to the base (<NUM>) and foldable to form a box sidewall, where the free sides of the segments (<NUM>), designed to be joined to form the edges of the box sidewall, are bevelled to define oblique faces (<NUM>) contained in the thickness of the segments (<NUM>), comprising:
- a supporting structure (<NUM>) configured to enable the blank (<NUM>) to move in a feed plane along a longitudinal feed direction to convey it to a gluing station;
- at least one liquid glue dispensing nozzle (<NUM>) movable along a predetermined direction parallel to the feed plane in such a way as to spread the glue on one or more of the oblique faces (<NUM>),
wherein the supporting structure (<NUM>) comprises:
- positioning means (<NUM>) operating on the blank (<NUM>) to move it to a predetermined longitudinal position in the gluing station;
- locking means (<NUM>) operating on the blank (<NUM>) in order to hold the blank in place in the same plane as the feed plane, while it is in the predetermined longitudinal position,
wherein the supporting structure (<NUM>) further comprises a first and a second guide (<NUM>) positioned longitudinally in the feed plane and shaped in such a way as to prevent transversal movements of the blank (<NUM>) and to slidably support lateral end portions of segments (<NUM>) of the blank (<NUM>),
wherein the locking means (<NUM>) include jaws (<NUM>) which are movable between an open position, of non-interference with the blank (<NUM>), and a closed position, wherein the jaws (<NUM>), in the closed position, are configured to operate on the blank segments (<NUM>) resting on the guides (<NUM>) in order to keep them in the feed plane,
wherein the jaws (<NUM>) are connected to corresponding actuators (<NUM>),
characterized in that the actuators (<NUM>) are associated with the guides (<NUM>), so that the blank (<NUM>) is locked at the predetermined longitudinal position while keeping it in the same plane as the feed plane, through the jaws (<NUM>) which are moved between the open position and the closed position, where the jaws (<NUM>) operate on the blank segments (<NUM>) resting on the guides (<NUM>) in order to keep them in the feed plane.