APPARATUS AND METHOD FOR FORMING A BOX MADE OF PAPER OR PAPERBOARD HAVING LATERAL EDGES OF DIFFERENT HEIGHTS Technical field

This invention relates to a method and an apparatus for forming a box made of paper or paperboard having lateral edges of different heights, that is to say, having upper edges which are angled relative to the surface on which the box rests.

Background art

The technical field of this invention is that of industrial processing of sheets of paper or paperboard for forming boxes with a high quality and finish. To make such boxes, shaped sheets are used, called blanks, consisting of a bottom and a plurality of panels connected to the bottom and designed to be folded relative to the bottom to constitute a lateral wall of the box. As regards the configuration of the blank, it generally has a number of segments equal to the number of sides of the bottom and each segment is connected to a corresponding side of the bottom. This type of blank is generally known as "petal-type".

However, it should be noticed that blanks with other shapes are also used. For example, it is possible that the number of segments is equal to (or greater than) the number of sides of the bottom, but that the number of segments directly connected to the bottom is less than the number of sides of the bottom, since some segments are connected to other segments.

In such a case, the blank is usually called "H-type" or "T-type" or "cross- type", depending on the configuration of the blank when it is extended on a surface.

If the number of segments is greater than the number of sides of the bottom, there are segments associated with other segments and which can be folded laterally to cover the same face of the lateral wall of the box, each encompassing its own vertical edge of said face.

It should be noticed that this invention is not applied irrespective of the type of blank used.

As regards the industrial process which begins with the blank and arrives at the finished box, it should noticed that the process comprises two separate steps: a step of forming the box and a subsequent step of covering the box by applying a covering sheet on it.

This invention specifically relates to the box forming step.

Said forming step in turn comprises two steps one after another: a first, folding step and a subsequent, sealing or closing step.

During the folding step the various panels of the blank (which was initially flat) are folded around the perimeter of the bottom to form the lateral wall of the box. The lateral wall of the box forms as many lateral edges as there are vertices of the bottom. Each lateral edge is formed by a pair of adjacent side edges which belong to consecutive folded panels.

In particular, machines for forming boxes usually comprise a mould able to move vertically and operatively coupled with an inner surface of the bottom and the lateral wall of the box for folding the panels of the blank, by making them interact with fixed contact elements.

At the end of the step of folding the panels around the bottom, the lateral edges are open, therefore, the adjacent panels must be connected to close the lateral edges.

Thus, in a subsequent sealing step the open lateral edges of the lateral wall of the box are joined (that is to say, closed). Sealing is usually carried out by applying sealing strips to the open lateral edges in order to close them.

In particular, machines for forming boxes usually comprise sealing heads having respective sealing tape dispensers and applicator elements

("pressers") set up to apply strips of the sealing tape to corresponding open lateral edges of the box. The sealing heads can move towards and away from the box between a position in which they do not interfere with it and a sealing position, in which they operate on corresponding open lateral edges to press the strips of tape against the respective lateral edges of the box, thereby sealing them.

During the sealing step, the function of the mould is to act as a constraining element operatively fitted to size in the space inside the box during the action of the pressers, so as to prevent the pressers from deforming the lateral wall of the box.

Within that scope, machines were produced, designed to form boxes having different shapes.

A particularly sought after shape is that of boxes called "oblique", that is to say, boxes made of paper or paperboard having lateral edges of different heights.

In a traditional, non-oblique box, the upper edges (those opposite the bottom edges) lie in a plane parallel with that defined by the bottom.

In contrast, in oblique boxes, at least one of the upper edges is not parallel with the plane defined by the bottom.

In light of this, it should be noticed that this invention is intended particularly for the step of sealing oblique boxes.

Indeed, the prior art machines, developed to form traditional boxes, are designed to apply sealing strips of identical length to the open lateral edges.

A machine of that type is described in patent application No. BO2008A000756 by the same Applicant, which performs a sequence of sealing steps, each one sealing only all of the edges having the same length, and in particular the edges with the lower length out of those still not sealed. Between two successive sealing steps, said type of machine lowers the mould and, consequently, the box, to align the longer edges with the heads during the second sealing step.

Machines of that type can only completely seal the edge with lower length, therefore requiring at least two separate steps for sealing all of the edges. There are also similar prior art machines in which, unlike the method described above, during a first sealing step there is simultaneous sealing of all of the edges covering the same length, equal to the length of the shorter edges, therefore requiring a subsequent step of sealing the upper part of the longer edges which previously remained unsealed.

In this latter type of machine, the sturdiness and attractive appearance of the boxes are penalised because a sealing tape joint or partial superposing zone is created for the longer edges (which are sealed in two stages), as well as requiring two separate sealing steps for each box.

EP1609585A1 discloses box forming machine having sealing heads provided with tape activating elements which can be driven one independently form the other.

Disclosure of the invention

The aim of this invention is, therefore, to provide an apparatus and a method which overcome the above-mentioned disadvantages of the prior art.

In particular, the aim of this invention is to provide a method and an apparatus for forming boxes made of paper or paperboard having lateral edges of different heights, which is particularly fast.

Another aim of this invention is to provide a method and an apparatus for forming boxes made of paper or paperboard having lateral edges of different heights, with particularly simple operation and programming.

These aims are fulfilled by the apparatus and the method according to this invention, as described in the appended claims.

In particular, the apparatus according to this invention is characterised in that the sealing heads are supported in such a way that they can be vertically adjusted and they can be adjusted independently of each other, allowing them to be aligned with the upper edges of the respective lateral edges of the box to be sealed.

That is to say, the sealing heads can be positioned in such a way that they are adjustable along corresponding vertical axes which are parallel with the direction of movement of the mould, for simultaneously sealing lateral edges of different heights on the same box.

Moreover, preferably, the apparatus comprises an outfeed section for sealed boxes located below the zone (or area) in which the sealing heads operate, but in any case above the sealing head movement slides.

The method according to this invention is characterised in that the step of aligning the sealing heads with the lateral edges of the box occurs by aligning, independently of each other, the various sealing heads (and in particular the pressers) with the upper edge of the lateral edges.

Therefore, it is sufficient to unroll, for each sealing head, a length of sealing tape equal to the length of the respective lateral edge of the box in order to complete sealing of all of the lateral edges simultaneously, in a single step.

Brief description of drawings

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

- Figure 1 is a three-dimensional view of an apparatus according to this invention;

- Figure 2 illustrates a side view of the apparatus of Figure 1 in an operating configuration, with some parts cut away to better illustrate others;

- Figure 3 is a schematic view of the apparatus of Figure 1 , showing a side view in the operating configuration of Figure 2;

- Figure 4 is a three-dimensional view of the apparatus according to this invention, together with further box forming stations. Detailed description of preferred embodiments of the invention

The numeral 1 in the accompanying drawings denotes an apparatus for forming boxes made of paper or paperboard according to this invention. In particular, the apparatus 1 is an apparatus for forming oblique boxes 100, that is to say, boxes having lateral edges 101 of different heights and, therefore, at least one angled upper edge 102.

The boxes 100 are made from flat blanks made of suitably shaped sheets of paper or paperboard. In particular, the blanks comprise a bottom and a plurality of lateral panels which are connected to the bottom (preferably along pre-creasing lines).

The starting blank for the type of boxes mentioned above is described in patent application No. BO2008A000756 by the same Applicant, which is incorporated herein regarding the aspects relating to said blank.

The panels can be folded to form respective lateral panels 103 of the box 100 in such a way that the lateral panels 103, operating in conjunction with each other, form a lateral wall of the box 100 inferiorly associated with a bottom wall 104. When the lateral panels 103 are folded relative to the bottom wall 104, adjacent side edges of the corresponding lateral panels 103 form the above-mentioned lateral edges 101 of the box which are open, that is to say, not yet sealed together.

In this description reference is made to boxes 100 with a rectangular or square bottom, without thereby limiting the scope of the invention. Therefore, such boxes 100 comprise four lateral panels 103 and four lateral edges 101 . Two adjacent lateral edges 101 have a height (measured relative to the plane in which the bottom wall 104 lies) greater than that of the other two lateral edges 103. Consequently, two opposite upper edges 102 lie in an angled plane.

However, it should be noticed that this invention applies to apparatuses for forming boxes having any number of sides and formed from blanks of any type.

As shown in Figure 1 , the apparatus 1 comprises a plurality of sealing heads 2.

Each sealing head 2 comprises:

- a sealing tape 4 dispenser 3;

- a presser 5 designed to apply strips 6 of sealing tape 4 to corresponding open lateral edges 101 of the box 100.

Each sealing tape 4 dispenser 3 preferably comprises a system of rollers controlled by an actuator (for example, an electric motor), according to a substantially known technique.

Each presser 5 comprises an element having two plates joined along a join line and forming a predetermined angle, in such a way as to define a V-shaped cross-section.

The presser 5 is shaped in such a way that it can press a strip 6 of sealing tape against the adjacent edges of the folded lateral panels 103, forming the above-mentioned open lateral edges 101 of the lateral wall of the box 100.

Therefore, the angle formed by the V-shape of each presser 5 depends on the angle formed by the lateral edge 101 to be sealed. That angle depends on the number of lateral panels 103 of the box 100 and in particular on the shape of the bottom wall 104.

For boxes 100 with a rectangular bottom, the angle formed by the V-shape of the pressers 5 is a right angle.

Similarly, the number of sealing heads 2 is linked to the number of edges 101 to be sealed, therefore it depends on the number of lateral panels 103 of the bottom wall 104 and on the shape of the blank 105 (that is to say, the pre-shaped paper or paperboard blank sheet which is used to make the box).

Therefore, in the example illustrated in Figure 1 the apparatus 1 comprises an operating zone (or area) 7, designed to contain the box 100 to be sealed, around which four sealing heads 2 are positioned, each designed to be facing and operate on a corresponding open lateral edge 101 of the box 100. The sealing heads 2 can move towards and away from the operating area 7, therefore towards and away from the box 100, between a maximum back position, in which they do not interfere with the box 100, and a maximum forward position, for sealing, in which they operate on corresponding open lateral edges 101 to seal them.

It should be noticed that the sealing heads 2 can move towards and away from the box 100 along a horizontal plane (where horizontal means substantially parallel with a base on which the apparatus 1 rests).

For that purpose, each sealing head 2 is mounted on a respective slide 8 able to slide along a horizontal guide 9.

In the embodiment illustrated in Figure 1 , said guides 9 of the slides 8 define a first translation of pairs of sealing heads 2 towards or away from each other along a first direction. In that embodiment, the translation of the sealing heads 2 in a second horizontal direction, perpendicular to the first, is obtained by mounting the above-mentioned guides 9 of the slides 8 on respective longitudinal members 10 which are slidably mounted on respective guides 1 1 , the latter being positioned perpendicularly to the guides 9 of the slides 8.

The superposing of the two movements of each sealing head 2 on the guides 9, 1 1 causes the sealing heads 2 to be moved forward and backward towards and away from the box 100 positioned in the operating area 7.

The movement of the slides 8 is driven by respective first actuators 8a, for example pneumatic or hydraulic cylinders, or recirculating ball screw actuators. In the embodiment illustrated, the first actuators 8a comprise electric motors which are connected by belts to male - and - female screw kinematic mechanisms.

Similarly, the movement of the longitudinal members 10 is driven by respective second actuators 10a, for example pneumatic or hydraulic cylinders, or recirculating ball screw actuators.

In the embodiment illustrated, the second actuators 10a also comprise electric motors which are connected to male - and - female screw kinematic mechanisms.

In addition, each sealing head 2 has a body 201 , the presser 5 being slidably mounted with respect to said body 201 , in such a way that it can slide horizontally (but, preferably, not vertically); each head 2 further comprises an actuator (not visible in the figures, it is housed inside said body 201 of the head or inside a pipe 15 of the head 2) connected to the presser 5 to move it relative to the body 201 of the head 2, whereby the presser 5 can be moved towards and away from a corresponding vertical edge of the box, while the body 201 of the head 2 remains still.

In addition, the whole head 2 is movable as one with the slide 8.

Indeed, the whole head 2 is movable vertically, whereby the heads 2 can be positioned at different height relative to each other.

The vertical movement of the heads 2 and the movements of the heads 2 in a horizontal plane together with the slides 8 are performed at a setting of the machine, in particular, when the size or shape of the boxes to be formed has to be changed.

One the relative position of the head is set (vertically and horizontally), the movement of the pressers 5 forward and backward towards and away from the box 100 positioned in the operating area 7 is performed through said actuators integral with the heads 2.

Preferably, each presser 5 is connected to the respective head body 201 in such a way that it can slide horizontally, but not vertically; in other words, preferably, the each presser 5 has a vertical position which is fixed with respect to the vertical position of the corresponding head 2 (i.e. body

201 ).

The apparatus 1 also comprises a mould 12 (visible in Figure 2) able to move vertically (that is to say, perpendicularly to a horizontal movement plane of the sealing heads 2).

The mould 12 can move towards and away from the operating area 7 and is designed to intercept the bottom portion of the blank 105, moving downwards, causing folding of the lateral panels 103 relative to the bottom wall 104 by interaction of the lateral panels 103 with fixed contact elements (not illustrated), according to a known technique.

The mould 12 is operatively coupled with an inner surface of the bottom wall 104 and of the lateral wall of the box 100 (consisting of the folded lateral panels 103) for vertically lowering the box 100 in the operating area 7.

Therefore, the mould 12 is designed to lower the box 100 vertically relative to the sealing heads 2.

Moreover, the mould 12 forms a constraining element operatively fitted to size in a space inside the box 100, forming contact surfaces operatively in contact with the inner surfaces of the lateral panels 103, interacting with the pressers 5 to guarantee complete adhesion of the strips 6 of sealing tape on corresponding outer surfaces of the lateral panels 103.

Advantageously, each sealing head 2 can be positioned in an adjustable way along a direction perpendicular to the horizontal plane of movement of the sealing heads 2, that is to say, along a vertical direction.

In that way, the sealing heads 2 can be positioned at different heights relative to a box 100 positioned in the operating area 7.

Moreover, advantageously, the sealing heads 2 can be adjusted in that direction independently of each other. Therefore, it is possible to position one or more sealing heads 2 at one height and other sealing heads 2 at another height.

Preferably, operating on each sealing head 2 there are adjusting means 13, designed to position each sealing head 2 in at least two different operating positions, which are vertically spaced and which correspond to different heights relative to the horizontal plane of movement of the sealing heads 2.

Figure 3 shows a consequence of that: with such features, the apparatus can prepare all of the sealing heads 2 so that they are simultaneously aligned with all of the upper edges 101 a of the lateral edges 103 of the box 100, even if said upper edges 101 a are not at the same height, as in the case of "oblique" boxes to which this invention relates.

To provide support at different heights, the bottom of each sealing head 2 is supported by a telescopic support 14 which is interposed between the sealing head 2 and the respective slide 8.

The telescopic support 14 may comprise, for example, a pipe 15 with cylindrical cross-section (preferably with circular cross-section) slidably inserted in a tube 16.

Preferably, the adjusting means 13 are designed in such a way as to continuously vary the positioning of the sealing heads 2 between a minimum height position and a maximum height position relative to a horizontal reference plane (for example, a plane in which the apparatus rests on the ground, or one of the planes of movement of the sealing heads 2).

It should be noticed that the term "height" of the sealing heads 2 refers to the height at which said heads are positioned, that is to say, the height relative to the horizontal reference plane.

In the embodiment illustrated in Figures 1 and 2, the adjusting means 13 comprise, for each sealing head 2, a rack 17 style lifter associated with the respective telescopic support 14 for causing reciprocal sliding between the pipe 15 and the tube 16 and, therefore, lengthening or shortening of the telescopic support 14 itself.

In a preferred embodiment, the vertical movement of the sealing heads 2 is performed manually. In the embodiment shown in Figures 1 and 2, that can be done by an operator acting on an adjusting screw 18 which is mechanically connected to a pinion (not illustrated) which acts directly on the rack 17, which is fixed to the pipe 15.

Preferably, the rack 17 projects from a cylindrical surface of the pipe 15 and therefore, on the inner surface of the tube 16, there is a corresponding longitudinal recess in which the rack 17 is inserted and can slide.

To stably lock together the pipe 15 and the tube 16 in a predetermined position relative to each other, there is a clamp 19 applied on the tube 16 and designed to clamp it onto the pipe 15 so as to lock the pipe 15 in the tube 16. For that reason, the tube 16 may comprise, at its end which receives the pipe 15, a through notch 20 designed to allow greater radial deformability of the tube 16 under the action of the clamp 19, thereby promoting the action of gripping by friction on the pipe 15.

After application of the strips 6 of sealing tape, the box 100 leaves the operating area 7 and reaches an outfeed station 21 where it can be moved away, for example so that it can be conveyed to a subsequent covering apparatus.

The outfeed station 21 is positioned below the operating area 7.

Advantageously, the outfeed station 20 is vertically positioned at a level higher than the slides 8 and the longitudinal members 10.

That allows use of the space below the operating area 7, and between the telescopic supports 14, for housing the systems (of the substantially known type) for picking up and/or moving away the sealed boxes. At the same time, the space below the slides 8 and the longitudinal members 10 does not require the installation of such systems for picking up and/or moving away the boxes, and it may therefore be kept to a minimum. Consequently, said optimisation of space allows, without increasing the overall dimensions, use of the adjustable supporting system for the sealing heads 2 in machines which are structurally similar to the prior art ones but with fixed heads, from which the sealed boxes are usually expelled by means of suitable systems located below the level of the slides for movement of the sealing heads 2.

The method according to this invention comprises the following steps: a) preparing an "oblique" box, therefore having at least one upper edge 101 which is at an angle to the plane in which the bottom wall 104 of the box 100 lies;

b) preparing sealing heads 2 which are facing an operating area 7 and comprise respective sealing tape 4 dispensers 3 and pressers 5 designed to apply corresponding strips 6 of sealing tape 4 to corresponding open lateral edges 101 of the box 100;

c) moving the box 100 vertically to position it inside the operating area 7; d) vertically aligning each sealing head 2 and the box 100;

e) operating the dispensers 3 of the sealing heads 2 to unroll respective strips 6 of sealing tape 4;

f) moving the sealing heads 2 along a horizontal plane for pressing the strips 6 of sealing tape 4 on the open lateral edges 101 of the box 100, thus closing them.

Advantageously, the aligning step is performed by vertically aligning each sealing head 2 and the upper edge 101 a of the respective open lateral edge 101 of the box 100.

Said alignment, in particular, is performed by aligning the upper edge of each presser 5 and the upper edge 101 a of the corresponding lateral edge 101 .

When processing "oblique" boxes 100, that alignment results in the sealing heads 2 being positioned at least at two different heights relative to the horizontal plane of movement of the sealing heads 2.

Since each sealing head 2 has the presser 5 aligned with the upper edge 101 a of the respective lateral edge 101 , the step of operating the tape dispensers 3 of the sealing heads 2 is performed by unrolling, for each sealing head 2, a length of sealing tape 4 equal to the entire length of the respective open lateral edge 101 of the box 100.

This invention fulfils the preset aim and also allows further advantages. With the adjusting means 13 described above, it is possible to obtain perfect alignment between the upper edge of the pressers 5 and the upper edge 101 a of the respective lateral edge 101 of the box 100, irrespective of the fact that the box may have lateral edges 101 of different heights. That solution therefore allows vertical alignment between sealing heads 2 (pressers 5) and lateral edges 101 of the box 100 during a preliminary step of adjusting the vertical positioning of each sealing head 2 so as to have the sealing heads 2 adopt an overall configuration suitable for alignment with the lateral edges 101 of a box 100 with a predetermined shape.

That preliminary step may advantageously be performed during a size- change over for the boxes to be made and therefore does not necessarily have to be performed between successive steps of sealing the lateral edges 101 of boxes 100 one after another in the same size.

Therefore, the step of aligning the sealing heads 2 with the box 100 is preferably performed before moving the box 100 in the operating area 7. That simultaneous alignment of all of the sealing heads 2 (therefore, of all of the pressers 5) with the respective lateral edges 101 of the box allows all of the lateral edges 101 to be sealed in a single step. Therefore, to complete a single box, it is not necessary to repeat two or more alignment and sealing cycles for the open lateral edges.

There are two consequent advantages. The time needed to complete the sealing of a single box is reduced thanks to the fact that all sealing is performed in one step. Moreover, performing all sealing in one step avoids the sealing of lateral edges in two steps one after another, thus eliminating joins between strips of sealing tape which are superposed or placed side by side.

In addition to the above, with reference to the position of the outfeed station 21 , relative to the slides 8 and to the longitudinal members 10, the optimisation of space allows, without increasing the overall dimensions, use of the adjustable supporting system for the sealing heads 2 in machines which are structurally similar to the prior art ones but with fixed heads, from which the sealed boxes are usually expelled by means of suitable systems located below the level of the slides for movement of the sealing heads 2.

In particular, it should be noticed that the apparatus according to the invention comprises:

- at least two longitudinal members 10 supporting corresponding horizontal guides 9, with which the sealing heads 2 are slidably coupled; - a station 106 for receiving the blanks 105, located above the operating zone 7;

- an outfeed station 21 for the sealed boxes 100, located above the longitudinal members 10.

Preferably, the outfeed station 21 for the boxes 100 is positioned at the same height as the operating zone 7.

Preferably, the outfeed station 21 comprises guides 21 1 . Said guides 21 1 form tracks for the sliding of the boxes 100 along a direction A of expulsion for the boxes 100.

Preferably, the receiving station 106 comprises guides 206. Said guides 206 form tracks for the sliding of the blanks 105 along a direction B of feed for the blanks 105.

Preferably, the direction A of expulsion for the boxes 100 and the direction B of feed for the blanks 105 are at right angles to each other.

The direction A of expulsion for the boxes 100 and the direction B of feed for the blanks 105 are at right angles to each other, both being perpendicular to the direction C (preferably vertical) of movement of the mould 12 (that is to say, the direction of movement of the box 100 coupled with the mould 12).