DEVICE AND METHOD FOR SHAPING BOXES MADE OF COVERED

PAPER OR CARDBOARD

Technical field

This invention relates to a device and a method for shaping covered paper or cardboard boxes.

Background art

The technical field of this invention is that of industrial processing for covering paper or cardboard boxes, having a bottom wall and a lateral wall with a plurality of sides (normally four sides).

The boxes in question are made from shaped sheets of paper or cardboard, known as forming blanks.

More specifically, the boxes are formed from flat forming blanks consisting of a base and a plurality of panels connected to the base and designed to be folded relative to the base to constitute a lateral wall of the box.

As regards the industrial process which produces the finished box, it should noticed that the process comprises basically two steps: a step of forming the box and a subsequent step of covering the box by applying a pre-glued covering sheet (that is to say, a cover) on it. The covering blank generally has a number of panels equal to the number of sides of the base and each panel is connected to a corresponding side of the base.

The lines for automatic production of covered boxes comprise: a box forming machine (an example of a forming machine is disclosed in patent document US2350690A), a covering machine, a gluing device for the covering blanks and a placing device, which receives boxes from the forming machine, couples them with corresponding covering blanks received from the gluing device (positioning the base of the box on the base of the flat covering blank) and feeds to the covering machine the assembly comprising each box coupled with the respective covering blank; the covering machine provides the finished blanks at the outfeed.

The forming machine (normally referred to as "quadrangular") folds the panels of the forming blank relative to the base, from the horizontal position (coplanar with the base) to the vertical position; for this reason, the panels are folded by 90 degrees. This defines a plurality of vertical edges of the box (equal in number to the number of panels), each defined by lateral edges alongside consecutive folded panels.

The forming machine also stably joins the vertical edges of the box, for example by applying strips of heat sealing tape along the vertical extension of the edges.

It should be noted that a blank made of high quality paper is used for forming the box; more specifically, the forming blank is made from a plasticized paper, generally with a high basic weight.

In effect, the boxes must have a high level of quality and appearance.

In light of this, the sides of the lateral wall of the box should, ideally, lie on planes perfectly perpendicular to the plane of the base of the box.

However, this does not occur, as there is a "bulging" of the sides of the box, that is to say, a curving of the sides (in particular of the longest sides of the box, if it has a rectangular base), towards the outside of the box.

This results in problems of appearance and also a difficulty in any coupling of the box with a lid made to measure relative to the box.

The lines currently available for the industrial production (automated) of these boxes do not resolve this problem, and produce "bulging" boxes.

From patent document GB535939A it known a method for inserting shoulder strips in the cornered lower part of shoulder boxes.

Disclosure of the invention

The aim of this invention is to provide an alignment unit for covered cardboard boxes which overcomes the above mentioned drawbacks of the prior art.

More specifically, the aim of this invention is to provide a device and a method for shaping a plasticized paper or cardboard box from a flat blank having a base and a plurality of panels connected to the base which allows the effect of bulging to be irreversibly eliminated.

A further aim of the invention is to provide a device and a method for shaping a plasticized paper or cardboard box which is particularly fast and is at the same time particularly efficient.

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

More specifically, the shaping device according to this invention is designed to be used in an automatic production line for covered boxes, comprising:

- a machine for forming boxes from flat forming blanks made of plasticized paper or cardboard;

- a covering machine, configured for covering the boxes with covering blanks;

- a gluing device for distributing glue on the covering blanks;

- a placing device, designed to receive boxes from the forming machine and to couple them to corresponding covering blanks received from the gluing device, for feeding the covering machine with an assembly comprising one of the boxes coupled with a respective pre-glued covering blank.

Preferably, the boxes have sharp corners. Preferably, the boxes have sharp corners both at the inside and at the outside of the box.

The shaping device comprises a separate device relative to the other components of the above-mentioned line; in this case, it is preferably connected at the outfeed to the covering machine. This prevents any slowing down of the line.

Alternatively, preferably, the shaping device is integrated with the covering machine (or at the limit of the forming machine).

According to the invention, the shaping device has pads (that is, pressing means) configured for pressing from the outside to the inside of the box, on sides of the lateral wall, for deforming the sides towards the inside. This deformation is reversible, so the sides of the box, once the action of the pads has finished, adopt a vertical orientation perpendicular to the base of the box; at the same time, the deformation results in a loss of shape memory associated with the folded panels of the box, constituting the lateral wall, the shape memory causing the "bulging" effect, in combination with the restraining reaction due to the joining of the panels along the vertical edges.

In effect, the right angle folding of the panels is not sufficient to a stretch the fibre of the paper (which is plasticized); consequently, the panels tend to naturally return towards their original position, coplanar with the base. The device according to the invention allows the temporary deformation operation to be performed automatically to oppose and eliminate the bulging effect.

It should be noted that the fact of being able to perform the operation automatically and, therefore, in a controlled manner (exerting a pressure on the outer wall of the box) is important, since, if this operation were performed manually, there would be the risk of exerting too much pressure, and thereby damaging the box, or too little pressure, and therefore not effectively resolving the bulging problem.

In effect, the manual sensitivity of an operator would not be able to guarantee, in general, an acceptable result: too much pressure on the walls would result in the walls giving slightly inwards; too little pressure on the walls would make the operation extremely slow and without the guarantee of a satisfactory outcome.

The device for shaping a box comprises at least a first and a second pad; preferably, these pads are aligned along a longitudinal axis and face towards each other.

The pads are movable away from and towards each other along the longitudinal axis; an actuator is connected to the pads to move them.

The device also comprises a conveyor, for mutually positioning the box to be formed and the pads.

The shape of the conveyor varies according to whether the shaping device is a separate unit or incorporated in the covering (of forming) machine. In effect, the covering machine (and the forming machine) are already equipped with means for moving the box inside the machine, preferably along a vertical direction.

In light of this, it should be noted that the invention also provides a machine for covering paper or cardboard boxes using pre-glued paper blanks having a plurality of sides joined to a base.

For moving the box along a vertical path, the covering machine comprises a plate movable vertically and configured for supporting the base of the blank with the box coupled thereto. Preferably, the machine also comprises a bracket (or a die) configured for being rested on the base of the box and acting in conjunction with the plate for retaining the base of the box interposed therein (the plate is positioned below and the bracket is positioned above the base of the box).

Preferably, the plate is motor driven and connected to a control unit, for moving the box along a vertical path, between positions at predetermined heights; alternatively, the bracket could be motor driven and the plate passive (for example, attached to a return spring); or both the bracket and the plate could be motor driven.

The covering machine comprises:

- a plate movable vertically and configured for supporting the base of the blank with the box coupled thereto (the plate preferably acts in conjunction with the die or the bracket inserted inside the box for retaining the base of the box interposed between the plate and the die or the bracket);

- means for folding the sides of the blank arranging them in a vertical position with respective lower panels in contact with corresponding lateral walls of the box;

- means for folding upper panels of the sides of the blank towards the inside of the box moving them from upright position to horizontal position; - means for folding the upper panels of the sides of the blank in contact with inner faces of the corresponding lateral walls of the box;

- pressing means for pressing towards each other, for each lateral wall of the box, the upper panels and the lower panels of the sides of the blank coupled with the inner and outer face, respectively, of the wall.

Thus, the plate (and/or any bracket or die) constitute the conveyor of the shaping device.

The pads are movably connected to a frame of the covering machine. Preferably, the pads are positioned at a height lower than the pressing means (and lower than the means for folding the sides of the blank and the means for folding upper panels of the sides of the blank).

For this reason, operatively, the plate is configured for moving the box, upon completion of the covering, to a shaping station of a covering machine, preferably positioned below a pressing station; in the shaping station at least one pair of sides of the lateral wall of the box are positioned transversely and interposed relative to the pads, which are automatically moved towards each other to deform towards the inside the sides of the wall of the box.

Preferably, the covering machine comprises two pairs of pads movable along respective axes perpendicular to each other; the movement axes of the pads are both parallel to a horizontal plane supporting the covering machine and perpendicular to a vertical direction of movement of the plate, that is to say, of the conveyor of the covering machine and therefore of the shaping device integrated in the covering machine.

If the shaping device constitutes a separate unit, it is equipped with an independent conveyor, preferably a conveyor belt, configured for moving the box along a horizontal feed direction (parallel to the floor).

Moreover, the device comprises a control unit, which controls the automatic operation of the device.

The control unit is connected to the conveyor, for positioning the box relative to the pads with the longitudinal axis (of the pads) perpendicularly intersecting the sides of the first pair of sides.

The control unit is also connected to the actuator of the pads for moving the pads forwards from a withdrawn position, in which they do not interfere with the box, to an extracted position, in which they press the sides (of the first pair of sides of the box) from the outside deforming them towards the inside of the box.

It should be noted that, generally, the boxes have a rectangular base, so they have a pair of longer sides and a pair of shorter sides. The definition of first and second pair of sides is arbitrary.

It should be noted that, if the box has a rectangular base, it is generally sufficient to deform with the pads only one of the two pairs of sides, in particular the longer pair of sides.

In light of this, preferably, the shaping device comprises manipulating means configured for rotating the box by 90 degrees about an axis perpendicular to the base of the box; the manipulating means are positioned upstream of the pads, relative to a path for feeding the box using the conveyor.

The purpose of the manipulating means is to ensure that it is the long sides of the box to be intercepted by the pads.

Naturally, all the sides of the lateral wall of the box (both the pairs of sides, in particular) are deformed.

Preferably, the conveyor is configured for positioning the box with the sides of the first pair of sides intersected by the longitudinal axis of the pads at the centre line of the sides, relative to a direction transversal to the longitudinal axis and parallel to the base of the box.

This makes the action of the pads particularly effective and reduces the risk of damaging the box.

In light of this, preferably, the control unit is set up to receive and store geometrical data on the shape of the box; for example, the control unit is set up to receive data on the size of the base of the box, in particular on the length of the long sides of the base of the box. It should be noted that the control unit is, for example, an electronic, comprising a memory and a processor.

For this reason, preferably, the control unit is programmed to command the conveyor to place the box symmetrically relative to the longitudinal axis (of the pads), relative to a direction parallel to the sides of the first pair of sides and parallel to the base of the box; in practice, the control unit commands the conveyor to determine the stopping position of the box relative to the position of the pads, as a function of the length of the long sides of the base of the box.

Moreover, preferably, the control unit is programmed to command the actuator of the pads according to a predetermined path, set up as a function of an extension of the base of the box along a direction at right angles to the sides of the first pair of sides; in practice, the control unit commands the movement of the pads (with particular reference to the extracted position of the pads) as a function of the length of the short sides of the base of the box, which are operatively aligned with the longitudinal axis of the pads.

In light of this, preferably, the shaping device comprises at least one position sensor (for example a photocell or the like), positioned upstream of the pads relative to a feed direction of the conveyor belt, for detecting the presence of the box.

The control unit is connected to the sensor for stopping the conveyor belt when the longitudinal axis of the pads intersects the sides of the first pair of sides at their centre line, relative to the feed direction of the conveyor belt. In light of this, the control unit is programmed for calculating, upon receiving a position signal of the box from the sensor, the stopping position of the box, as a function of a speed of movement of the conveyor belt (in effect, the position of the sensor is fixed and known relative to the position of the pads).

This makes the device particularly simple, effective and fast.

Preferably, the pads are adjustable in height (that is, along the relative vertical adjustment axes), so that the longitudinal axis is also adjustable vertically. This allows the action of the pads to be optimised according to the type and dimensions of the box (this is particularly useful when changing the size of the box to be made on the line).

Preferably, the control unit comprises a timer and it is programmed to keep the pads in the extracted position, interacting with the sides of the lateral wall of the box, for a predetermined period of time (set in the control unit, with the possibility of varying the setting according to the type of box). Moreover, preferably, the actuator of the pads is equipped with a system for controlling the force applied against the walls of the box; this makes the device particularly reliable, avoiding risks of damaging the box due to incorrect settings.

For this reason, the invention also provides a method for shaping a plasticized paper or cardboard box from a flat blank having a base and a plurality of panels connected to the base and having a lateral wall with at least a first and a second pair of sides.

This method comprises the following steps:

- positioning box with the sides of the first pair of sides of the lateral wall positioned on vertical planes oriented along a transversal direction and interposed between a first and a second pad;

- moving two pads towards each other along a longitudinal axis, at right angles to the transversal direction;

- stopping pads in an extracted position, wherein the pads press the sides of the first pair from the outside towards the inside of the box, deforming them towards the inside of the box.

It should be noted that the invention also provides a method for automatic production of covered boxes, comprising the following steps:

- forming boxes from flat forming blanks made of plasticized paper or cardboard;

- gluing of covering blanks;

- coupling of covering blanks glued beforehand to corresponding boxes formed beforehand;

- covering of boxes using corresponding covering blanks.

According to this invention, such a method for automatic production of covered boxes also comprises a step for deforming towards the inside at least one side of the lateral wall of the box; preferably, deforming towards the inside at least the sides of a first pair of sides of the lateral wall of the box.

The deformation step occurs after the forming of the box, preferably after the covering of the box.

It should be noted that the deformation produced by the pads arranged in the extracted position and interacting with the corresponding sides of the box means that at least one portion of the sides is inclined relative to the base by an acute angle, less than 90 degrees.

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 is a schematic top plan view of a shaping device according to this invention, according to an embodiment wherein the device is separate;

- Figure 2 is an enlarged schematic top plan view of the shaping device of Figure 1 with a box in different operating steps;

- Figure 3 is an enlarged view of a detail the shaping device of Figure 1 .

- Figures 4 and 5 illustrate a shaping device according to this invention, integrated with a covering machine.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, and with reference in particular to Figures 1 to 3, the device 100 for forming boxes made of covered paper or cardboard according to this invention is used on lines for the production of cardboard boxes covered with sheets of paper. More specifically, the device 100 is used for shaping, that is, for restoring the alignment of at least two sides of the box 1 covered and leaving a machine 2 for covering the box 1 .

More specifically, the term box 1 means a container having a plurality of lateral walls 1 b, 1 c, 1 d, 1 e interconnected with the bottom base 1 a.

This description will make particular reference, but without thereby limiting the scope of the invention, to the covering of a box 1 with a quadrilateral cross-section (rectangular).

More specifically, the box illustrated has a pair of end walls 1 c, 1 e (short) and a pair of side walls 1 b, 1 d (long).

However, the device 100 described below is fully applicable to boxes of the most diverse shapes.

Moreover, preferably, the box 1 is made of cardboard, card or the like. The device 100 according to this invention is used, in this specific case, for re-aligning the long sides 1 b, 1 d of the finished box 1 so as to avoid the bulging towards the outside of the walls 1 b and 1 d.

The device 100 comprises a conveyor 3 for feeding the finished box 1 leaving the covering machine 2 (shown by a block in Figure 1 ) and along a feed path A.

Preferably, the conveyor is a belt 3 (as it will be referred to below).

The belt 3 has a drive unit 3m and it is synchronised with the covering machine 2.

The device 100 also comprises manipulating means 4 for orienting and positioning the box 1 placed along the belt 3 and it is able to position the box 1 with the long walls 1 b, 1 d parallel to the feed path A of the belt 3.

In other words, the manipulating means 4 rotate the box 1 by a right angle about an axis perpendicular to the base 1 a of the box 1.

The manipulating means 4 are positioned upstream of a pair of pad units 5 relative to the feed path A of the box 1 using the belt 3.

The unit 100 comprises a pair of pad units 5 configured for pressing on the sides of the box 1 . As mentioned, the pad units 5 are positioned along the belt 3, upstream of the means 4 for orienting the box 1 relative to the feed path A, and positioned on each side of the box 1 being fed, in such a way as to be facing a corresponding long wall 1 b, 1 d of the box 1 .

The unit 100 also comprises a sensor 6 for detecting the passage of the box 1 along the belt 3.

Preferably, the detection sensor 6 is positioned above the belt 3 in a position downstream of the manipulating means 4 and upstream of the pad units 5 again relative to the feed path A.

The unit 100 also comprises a control unit 7 for controlling at least the belt 3 and the pad units 5.

The unit 7 is also connected to the sensor 6 for detecting the box 1 and configured for receiving a signal from the same detection sensor 6.

It should be noted that, in the case illustrated, the box 1 leaves the covering machine 2 with the long walls 1 b, 1 d positioned transversely to the feed path A of the belt 3.

Preferably, the manipulating means 4 comprise a pin 8 with a vertical extension positioned on the belt 3 close to the outfeed area of the covering machine 2.

The pin 8 is positioned in such a way as to intercept the box 1 and allow the box 1 to rotate by an angle a (approximately 90°): in this way, its outfeed orientation is changed, positioning the long walls 1 b, 1 d parallel to the feed path A.

Preferably, the manipulating means 4 comprise a pair of vertical panels 9 and 10 positioned downstream of the vertical pin 8 and configured for defining a channel for passage of the box 1 in the rotated configuration and according to a predetermined trajectory.

The two panels 9 and 10 are supported by a portal 1 1 positioned above the belt 3.

The portal 1 1 is equipped with guides 12 and 13 for supporting and adjusting each panel 9 and 10 for modifying their mutual distance and/or their inclination relative to the feed path A.

It should be noted that (in the case illustrated in Figures 1 and 2) one panel 9 is positioned parallel to the feed path A whilst the other panel 10 is inclined towards the outside starting from the infeed area of the box 1 . This configuration allows the initial space to be left necessary for the rotation of the box 1 with successive mandatory rectilinear orientation and positioning of the box 1 close to the pad units 5.

It should be noted that one of the panels 9, the rectilinear one, defines the reference and alignment plane relative to the pad unit 5.

Preferably, the detection sensor 6 comprises a photocell 14 for detecting the box 1 .

The photocell 14 is connected to an upper crosspiece 15 of the portal 1 1 and connected to the control unit 7.

In light of this, the control unit 7 receives the signal from the photocell 14 when the front end of the box 1 passes beyond the photocell 14.

The unit 7 is designed to receive and store geometrical data on the shape of the box 1 and checks the feed speed of the box 3 by controlling its drive unit 3m.

In light of this, the unit 7, having stored the geometrical data of the box 1 (dimensions of the box 1 ), is programmed for:

- commanding the belt 3 to place the box 1 symmetrically about the longitudinal axis X, relative to a direction parallel to the sides 1 b, 1 d (parallel to the feed path A) of the pair of long sides 1 b, 1 d and parallel to the base 1 a of the box 1 , and/or

- commanding the movement of the pads 5 setting up a predetermined path, as a function of an extension of the base 1 a of the box 1 along a direction at right angles to the sides 1 b, 1 d.

In other words, the unit 7 moves the box 1 forward between the two pad units 5 until reaching a predetermined position of the long side panels 1 b, 1 d (centred) relative to the pad units 5.

Preferably, each pad unit 5 is an actual pad comprising a pushing head 16 and 17 connected to an actuator 18, 19 for moving the pushing head in the two directions 16 and 17.

The two pads 5 are aligned along the above-mentioned longitudinal (reference) axis X and have the corresponding heads 18 and 19 turned towards each other.

Preferably, the two pads 5 are adjustable in height, so that the longitudinal axis X is also adjustable vertically.

Preferably, the two actuators 18 and 19 are connected to and controlled by the control unit 7 for moving in a controlled manner both the movement speed and the operational pushing stroke on the heads 16 and 17, as a function of the deformation effect or "yield" necessary on the walls 1 b, 1 d of the box 1 .

It should be noted that each pressing head 16 and 17 has a curved contact profile with the wall to deform the corresponding wall 1 b, 1 d of the box 1 with greater intensity at the centre, but also with a lesser thrust on the remaining surface of the wall 1 b, 1 d of the box 1 : in this way, the yield is more distributed and is sustained / absorbed by the entire wall 1 b, 1 d which, after the moving away of the heads 16 and 17, returns to a rectilinear position aligned with the actual perimeter of the box 1 .

It should therefore be noted that, as mentioned, the control unit 7 is connected to the belt 3, for positioning the box 1 relative to the pads 5 with the longitudinal axis X intersecting perpendicularly the pair 1 b, 1 d of long sides of the box 1 .

The control unit 7 is connected to the corresponding actuators 18, 19 of the pads 5 for moving the pushing heads 16, 17 from a withdrawn position, in which they do not interfere with the box 1 , to an extracted position, in which they press the sides 1 b, 1 d from the outside deforming them towards the inside of the box 1.

It should be noted that the control unit 7 is connected to the photocell 14 for stopping the conveyor belt 3 when the longitudinal axis X of the pads 5 intersects the long sides 1 b, 1 d at their centre line, relative to the feed direction A of the conveyor belt 3.

The device 100 for shaping boxes 1 described up to now can be inserted in an automatic production line for covered boxes 1 , comprising:

- a machine 20 for forming boxes 1 from flat forming blanks made of plasticized paper or cardboard;

- a covering machine 2, configured for covering the boxes 1 with covering blanks;

- a gluing device 21 for distributing glue on the covering blanks;

- a placing device 22, designed to receive boxes 1 from the forming machine 20 and to couple them to corresponding covering blanks received from the gluing device 21 , for feeding the covering machine 2 with an assembly comprising one of the boxes coupled with a respective pre-glued covering blank.

This line (the previous machines or devices of which are indicated with blocks in Figure 1 ) comprises the device 100 for shaping the box 1 connected at the outfeed to the covering machine 2.

This invention provides a method for shaping a plasticized paper or cardboard box 1 from a flat blank having a base 1 a and a plurality of panels connected to the base and having a lateral wall with at least a first 1 b, 1 d and a second 1 c, 1 e pair of sides.

According to the invention, the method comprises the following steps:

- positioning box 1 with the first pair of sides 1 b, 1 d of the lateral wall positioned on vertical planes oriented along a transversal direction (corresponding to the feed path A) and interposed between a first and a second pad 5;

- moving two pads 5 towards each other along the longitudinal axis X, at right angles to the transversal direction A;

- stopping pads 5 in an extracted position, wherein the pads 5 press the first pair of sides 1 b, 1 d from the outside towards the inside of the box 1 , deforming them towards the inside of the box 1.

It should be noted that the base 1 a of the box 1 has a rectangular shape, so that the box 1 has a pair of long sides 1 b, 1 d and a pair of short sides 1 c, 1 e.

In this case, the positioning step comprises a preliminary step for orienting the box 1 to ensure that it is the long sides 1 b, 1 d to define the sides of the first pair of sides, interposed between the pads 5.

Preferably, the positioning step comprises a feeding of the box 1 in a transversal direction A and an automatic stopping of the box 1 when a centre line of the sides 1 b, 1 d of the first pair of sides is intersected by the longitudinal axis X of movement of the pads 5.

Preferably, the positioning step comprises a control of the forward movement of the box 1 as a function of

- a position signal of the box 1 detected by a sensor 6 positioned upstream of the pads 5,

- a length of the sides 1 b, 1 d of the first pair of sides evaluated parallel to the base 1 a of the box 1 and

- a feed speed of the box 1.

In the example illustrated in Figures 4 and 5, the device 100 for shaping the boxes 1 according to this invention is integrated in the covering machine 3.

The covering machine 3 comprises a plate and a bracket for vertically moving the blank with the box coupled thereto (plate not illustrated) and a series of heads for covering the box 1 with the sides of the blank for covering the inner and outer faces of the box 1.

Figures 4 and 5 illustrate one of the heads 23 for covering the box 1 .

Preferably, on a covering machine 3 there are four heads 23 positioned in pairs facing each other so as to be able to act on contiguous sides of the blank.

The pads 5 are movably connected on a corresponding tower 24 supporting at least one pair of these covering heads 23.

Preferably, the pads 5 can be connected to all four towers 24 of the covering heads 23. Preferably, the pads 5 are positioned lower than the covering heads 23 and are reached by the box 1 using the movement of the plate.

Each pad 5 comprises a corresponding pushing head 16 or 17 connected to the actuator 18 or 19 for moving it to and from the box 1 .

Each pad 5 is supported by a corresponding frame 25 connected to the corresponding tower 24.

Preferably, the frame 25 is adjustable vertically in height along the tower 24.