Method and apparatus for wrapping cardboard boxes

Abstract

Method for wrapping a box, comprising arranging a supporting device (10); placing a wrapping sheet (200) on the supporting device (10) to define a supporting area (120) in contact with the sheet (200) and a free area (220) not in contact with the sheet (200); transmitting a light radiation (B1) having an effective wavelength (wB) inside the infrared band from a lighting system (20) to an optical acquisition system (30), the supporting device (10) being transparent to the light radiation (B1); positioning the sheet (200) between the lighting system (20) and the optical acquisition system (30); capturing by means of said optical acquisition system (30) an image (I) of the sheet (200); as a function of the captured image (I), positioning a box (100) on the sheet (200); moving the joined box (100) and sheet (200) to a wrapping station.

Description

[0001] METHOD AND APPARATUS FOR WRAPPING CARDBOARD BOXES

[0002] The present invention falls within the technical field of automatic machines for manufacturing wrapped rigid boxes. More specifically, the present invention concerns a method and an apparatus for wrapping a preformed rigid cardboard box.

[0003] In particular, the present invention finds preferred but not exclusive application in the field of automatic machines for manufacturing cardboard boxes wrapped with a pre-glued wrapping sheet, intended for example for the luxury sector, to which reference may be made hereinafter without loss of generality.

[0004] Wrapped cardboard boxes are currently manufactured in automated production lines with different stations that include respective processing machines which operate in two different stages: an initial forming stage, in which the box is pre-formed starting from a blank sheet of paper or cardboard appropriately shaped and folded, and a subsequent wrapping stage, in which a pre-glued wrapping sheet is applied to the pre-formed box in order to wrap it, at least on the respective external walls, i.e. the walls mainly exposed to a user. Generally, the blank sheet of paper or cardboard consists of a base and a plurality of panels connected to the base and foldable with respect to the base to form a side wall of the box, while the wrapping sheet is a flat sheet having a main wall shaped like the base of the blank sheet of paper or cardboard, and panels connected to the main wall and foldable to wrap the side walls of the preformed box.

[0005] An automated production line for producing wrapped rigid boxes typically consists of a forming machine which forms the boxes starting from pre-cut blanks, a gluing equipment for applying an adhesive element to the wrapping sheet, a positioning equipment which receives a formed box from the forming machine and a corresponding pre-glued wrapping sheet from the gluing equipment to couple them by centering the base of the box on the main wall of the wrapping sheet, said main wall thus defining a junction area of the wrapping sheet, and then a wrapping station that comprises a wrapping machine which receives the assembly consisting of each box coupled to the respective wrapping sheet from the positioning device and completes the wrapping to make the finished boxes available at the outfeed.

[0006] In this description as well as in the claims attached thereto, some terms and expressions are deemed to assume the meaning given in the definitions that follow, unless otherwise explicitly indicated.

[0007] The term “box” means any container suitable for containing a plurality of articles for the purpose of their packaging, where the box can be made starting from a blank to be folded and subsequently fixed at its edges or panels.

[0008] The term “blank” means a shaped sheet of apposite material and thickness, which can be folded to form the box. Preferably, the blank is made of cardboard and has creases or other areas of weakening of the material, for example incisions or perforations, capable of facilitating the folding of the cardboard at predefined folding lines.

[0009] A “wrapping sheet” is a shaped sheet of apposite material and thickness, suitable for being solidly coupled and wrapped by folding around a box, to at least partially wrap the box. Preferably, the wrapping sheet is made of paper or cardboard based material.

[0010] The “outer surface” of a wrapping sheet means the side of the sheet which will be visible to the user of the wrapped box. The “inner surface” of a wrapping sheet means the side of the sheet opposite to the side which will be visible to the user of the wrapped box, i.e. the side intended to be coupled with the box to be wrapped.

[0011] A wrapping sheet is “pre-glued” when one of its surfaces, in particular the inner surface, is at least partially treated with an adhesive substance, e.g. glue.

[0012] A first surface (or area or face) of one object is said to be “entirely positioned” into a second surface (or area or face) of another object when said first surface rests on and is contained in the second surface of the other object, with the result that the first surface of the object fits into the second surface of the other object.

[0013] An object is said to be "transparent" to light radiation when it can be passed through by such light radiation, with negligible reflection or zero reflection of the same light radiation. An object is said to be "partially transparent" to light radiation both in the case in which a portion of the object can be passed through by such light radiation with negligible reflection or zero reflection, and in the case in which said object can be passed through entirely or in part by such light radiation in a diffuse manner, that is, when said object is entirely or partially translucent to the aforementioned light radiation.

[0014] In the automated production line described above, the pre-glued sheet is usually transported from the gluing equipment to the positioning equipment by means of a moving and supporting device, e.g. a conveyor belt or slat conveyor. In particular, the wrapping sheet lies with its outer surface in contact with the conveyor belt. As a result, the inner surface of the wrapping sheet is exposed to natural or artificial light, in other words it is visible.

[0015] In the step for coupling the formed box with the pre-glued sheet, the positioning equipment captures, by means of a respective optical acquisition system, an image of the pre-glued sheet placed on the conveyor belt, in particular of the inner surface of the sheet, it identifies, on the basis of the captured image, the position and orientation of this sheet with respect to a predetermined coordinate system, then it moves the box, for example translates and / or rotates it, so as to center the base of the box on the main wall or junction area of the wrapping sheet. The applicant noticed that the accuracy of the positioning equipment depends significantly on the characteristics of the image captured by the optical acquisition system.

[0016] For instance, the applicant found that the precision of the positioning equipment decreases and therefore the positioning equipment is subject to errors in positioning the box on the sheet which are greater and more frequent the lower the chromatic contrast between the inner surface of the wrapping sheet and the conveyor belt. More specifically, a poor contrast between the colour of the inner surface of the wrapping sheet and the colour of the conveyor belt does not allow the extension and position of the wrapping sheet to be identified exactly with respect to the predetermined coordinate system. This phenomenon is more frequent in conditions of weak natural or artificial light, to which the inner surface is exposed.

[0017] As a further example, the applicant also noted that the precision of the positioning equipment decreases as the reflection coefficient of the inner surface increases. Indeed, the higher the reflection coefficient of the inner surface of the wrapping sheet, the greater the diffusion of natural or artificial light that reflects on such inner surface and generates a glare around the wrapping sheet itself, altering the visible profile of the wrapping sheet. This phenomenon, contrary to the previous example, is more frequent in conditions of bright natural or artificial light to which the inner surface is exposed. Also in this case, therefore, the positioning equipment is not able to correctly identify the extension and position of the wrapping sheet with respect to the predetermined coordinate system.

[0018] The applicant therefore understood that the core problem, in the aforementioned conditions of poor chromatic contrast between the inner surface of the wrapping sheet and the conveyor belt and / or high reflection coefficient of the aforementioned inner surface, lies in the difficulty of the optical acquisition system to accurately detect the outline or even just a portion of the outline of the wrapping sheet.

[0019] The Applicant verified that the use of high precision and accuracy optical acquisition systems, in addition to implying a significant increase in costs and a reduction in the robustness of the production line, is not always able to solve the problem.

[0020] Indeed, the performance of high precision and accuracy optical acquisition systems depends in any case on the light conditions to which the inner surface of the wrapping sheet is exposed, conditions that determine the resulting chromatic contrast between the inner surface and the conveyor belt and the reflection of light on said inner surface. In particular, a brighter light allows to improve the aforementioned contrast but increases the risk of glare in the case of a high reflection coefficient of the inner surface, and a weaker light reduces or eliminates this risk of glare but does not allow to precisely distinguish the inner surface of the wrapping sheet from the conveyor belt. The applicant also saw that a first solution to this problem is represented by the possibility of installing on the production line a conveyor belt of an appropriate colour based on the colour of the inner surface of the wrapping sheet to be processed, so as to have a sufficient contrast between the conveyor belt and the wrapping sheet. However, this first solution requires long machine downtimes necessary for the re-setup of the production line, which are not tolerable in particular for medium and small scale productions, such as the production of wrapped boxes intended for the luxury sector, in addition to requiring a large and unpredictable number of conveyor belts available to the operator. Furthermore, this first solution does not solve the problem of glare of the optical acquisition system by inner surfaces with a high reflection coefficient.

[0021] The applicant therefore perceived that the precision of the positioning equipment can be improved and made independent of the type of inner surface of the wrapping sheet, by contrasting and attenuating the effect of the light to which such inner surface is exposed. Hence, with reference to the automated production lines described above, the applicant realized that by using a lighting system placed behind the inner surface, in other words directed towards the outer surface of the wrapping sheet, the inner surface is backlit with respect to the optical acquisition system of the positioning equipment that shoots it. This allows the optical acquisition system to visualize the outline of the wrapping sheet and to accurately detect the outline of the wrapping sheet or even just a portion of this outline.

[0022] The Applicant finally found that a method and the related apparatus for wrapping boxes, which provide for positioning the wrapping sheet between the lighting system and the optical acquisition system in order to obtain a backlit image of this sheet or of a portion thereof, allow to achieve several advantages including that of maintaining a high precision of the positioning equipment, regardless of the type of inner surface of the wrapping sheet and of the light to which such inner surface is exposed.

[0023] In its first aspect, therefore, the present invention is directed to a method for wrapping a box with a wrapping sheet.

[0024] Preferably, the method comprises the step of arranging a supporting device having a first surface and a second surface opposed to each other.

[0025] Preferably, the method comprises the step of placing a wrapping sheet on the supporting device. This defines, on the first surface, a supporting area in contact with the sheet and a free area not in contact with said sheet. Preferably, the supporting area has a respective perimeter edge adjacent to the free area.

[0026] Preferably, the method comprises the step of transmitting a light radiation from a lighting system to an optical acquisition system.

[0027] Preferably the light radiation has at least an effective wavelength inside the infrared band.

[0028] Preferably the supporting device is at least partially transparent to the light radiation transmitted by the lighting system. In an equally preferred manner, the supporting device can be totally transparent to the light radiation transmitted by the lighting system.

[0029] Preferably the supporting device is transparent to the visible light, namely transparent to the human eye.

[0030] Preferably, the method comprises the step of positioning between the lighting system and the optical acquisition system the sheet placed on the supporting device. This prevents that part of the light radiation is transmitted from the lighting system to the optical acquisition system. Preferably, the method comprises the step of capturing by means of the optical acquisition system an image of at least one portion of the sheet placed on the supporting device. In an equally preferred manner, the method can comprise the step of capturing by means of the optical acquisition system an image of the whole sheet placed on the supporting device.

[0031] Preferably, the method comprises the step of positioning on the sheet, as a function of the captured image, a box to be wrapped. This allows to join the box and the sheet.

[0032] Preferably, the method comprises the step of moving the box joined to the sheet to a wrapping station. In a second aspect, the present invention concerns an apparatus for wrapping a cardboard box with a wrapping sheet.

[0033] Preferably, the apparatus comprises a lighting system adapted to transmit a light radiation having at least an effective wavelength inside the infrared band.

[0034] Preferably, the apparatus comprises an optical acquisition system adapted to receive said light radiation.

[0035] Preferably the lighting system and the optical acquisition system are part of a positioning equipment of the apparatus according to the present invention.

[0036] Preferably, the apparatus comprises a supporting device intended for supporting the wrapping sheet. Preferably the supporting device is placed between the lighting system and the optical acquisition system. Preferably the supporting device is at least partially transparent to said light radiation. In an equally preferred manner, the supporting device is fully transparent to said light radiation.

[0037] Thanks to the present solution, which provides a supporting device that is placed between the lighting system and the optical acquisition system and is partially or entirely transparent to the light radiation emitted by the lighting system, the intensity of the light radiation downstream of the supporting device (with respect to the direction of propagation of the light radiation) turns out to be a substantially binary quantity. In particular, the intensity of the light radiation is maximum at the free area of the supporting device not occupied by the wrapping sheet, since the light radiation is transmitted from the supporting device to the optical acquisition system in a substantially uniform manner over the entire free area, while it is minimal or zero at the supporting area of the supporting device occupied by the wrapping sheet, since the light radiation is largely or totally absorbed by the wrapping sheet in a substantially uniform manner over the entire supporting area. The wrapping sheet is therefore backlit with respect to the optical acquisition system of the positioning equipment, which sees for example a cutout with low light intensity, in particular a dark or black cutout, representative of the wrapping sheet or a portion thereof, which stands out against a high light intensity background, in particular a bright or white background.

[0038] The cutout of the wrapping sheet seen by the optical acquisition system is therefore in contrast and clearly visible with respect to the conveyor belt, regardless of the colours of the inner surface of the wrapping sheet and of the conveyor belt.

[0039] Furthermore, since the surface of the wrapping sheet seen by the optical acquisition system is not directly illuminated but in shadow, on the surface of the wrapping sheet, there is no reflection of direct light responsible for dazzling the optical acquisition system.

[0040] The Applicant therefore verified that the present solution is surprisingly capable of both solving the problem of a possible poor chromatic contrast between the inner surface of the wrapping sheet and the conveyor belt, and of counteracting the unwanted phenomenon of glare of the optical acquisition system.

[0041] The applicant also positively found that the solution according to the present invention has the advantage of being able to capture extremely sharp images, even at long distances, by emitting infrared light radiation that is invisible to the human eye. In this way the wrapping apparatus can also be placed in proximity to devices or components sensitive to ambient light, without any risk of interference with such devices or components and therefore removing the need for appropriate countermeasures, such as shielding.

[0042] In at least one of the aforementioned aspects, the present invention may additionally have at least one of the preferred features set forth below.

[0043] In one or more embodiments, the method comprises a tuning phase and one or more operational phases. Preferably said one or more operational phases follow the tuning phase.

[0044] Preferably the tuning phase comprises setting the light radiation emitted by the lighting system to a starting value, in particular as a function of a saturation value of the optical acquisition system. This allows setting, preferably once before the operational phases, the intensity of the light radiation emitted by the lighting system to an appropriate value which doesn’t saturate one or more sensors of the optical acquisition system, so that the acquisition of images of the sheet in backlight occurs without dazzling the optical acquisition system, in particular without glare due to receiving direct light emitted by the lighting system.

[0045] In one or more embodiments, the method comprises maintaining the intensity of the light radiation emitted by lighting system at the starting value, in particular during the following one or more operational phases.

[0046] Preferably, the method comprises identifying in the captured image a shadow region having a first light intensity, and a light region adjacent to the shadow region and having a second light intensity higher than the first light intensity. In this way the captured image provides binary information, in particular the presence of the wrapping sheet at the shadow region and the absence of the wrapping sheet at the bright region, and allows to identify in a precise and reliable manner the cutout of the wrapping sheet or of a portion of the wrapping.

[0047] Preferably, the method comprises locating, on the first surface of the supporting device, at least a piece of the perimeter edge of the supporting area as a function of the shadow region and light region identified in the captured image.

[0048] Preferably, the method comprises defining, on the wrapping sheet, a junction area as a function of the located piece of the perimeter edge.

[0049] Preferably, the positioning equipment of the apparatus according to the present invention comprises a transfer system. Preferably the transfer system is able to position a box to be wrapped on the sheet. In an equally preferred manner, the transfer system is able to move the box joined to the sheet from the supporting device to a wrapping station.

[0050] Preferably, the step of positioning a box to be wrapped on the sheet is executed by means of the transfer system.

[0051] Preferably, the step of positioning a box to be wrapped on the sheet is executed as a function of the junction area. Thanks to the precise and reliable identification of the cutout of the wrapping sheet, the positioning equipment is able to circumscribe within this cutout a precise area where the box to be wrapped has to be positioned, so that the coupling is optimized and the resulting wrapped box has an excellent aesthetic result, as required for wrapped boxes intended for the luxury sector.

[0052] In one or more embodiments, the box comprises a base and a plurality of lateral walls connected to said base.

[0053] Preferably, the step of positioning comprises at least one of translating the box and rotating the box so that the base is entirely positioned into the junction area. By combining translations and / or rotations, the positioning of the box allows both to bring the base of the box closer to the junction area of the wrapping sheet, and to orient this base as a consequence of any unwanted obliquities of the sheet, for example with respect to the edge of the supporting device (for example, due to the fact that the sheet has been positioned inappropriately on the supporting device or displaced while lying on the supporting device). In this way, any misalignments and offsets between the base of the box and the junction area of the wrapping sheet are counteracted and do not affect the resulting wrapped box.

[0054] In one or more embodiments, the lighting system transmits a light beam inside a wavelength base range.

[0055] Preferably the effective wavelength belongs to a wavelength working range. Preferably the wavelength working range is included inside the wavelength base range. In this way the lighting system can be chosen independently of its emission band, which can possibly be very wide (such as that of a common and cheap incandescent lamp) and not necessarily narrow and limited to the wavelength working range or even to the effective wavelength of the light radiation, advantageously reducing the design constraints without compromising the effectiveness of the method.

[0056] In one or more embodiments, the supporting device comprises at least a prime zone transparent to the wavelength working range, in particular to transmit a component of the light radiation having effective wavelength that belongs to said wavelength working range. Preferably the method comprises the step of positioning between the lighting system and the optical acquisition system the sheet placed on the supporting device at the prime zone. Thanks to the transparence of the prime zone to the wavelength working range, the light radiation having one or more effective wavelengths belonging to the wavelength working range is transmitted substantially without attenuation through the prime zone. In this way, the background against which the outline of the wrapping sheet seen by the optical acquisition system stands out appears particularly clear, for example bright or white, and therefore in clear contrast to this outline.

[0057] In one or more embodiments, the apparatus comprises an optical filter, in particular to filter radiations of the light beam having respective wavelengths outside the wavelength working range. Preferably, the optical filter is located between the lighting system and the first surface of the supporting device. In an equally preferred manner, the optical filter is located between the second surface and the optical acquisition system.

[0058] In one or more embodiments, the method comprises the step of filtering by means of an optical filtering device components of the light beam transmitted by the lighting system. Preferably such components have respective wavelengths that don’t belong to the wavelength working range. In this way it is possible to consider any lighting system, even one having a possibly very wide emission band such as that of a common and cheap incandescent lamp, implementing in any case a particularly efficient method. Thanks to the filtering, indeed, any light radiation having wavelengths different from the effective wavelengths and potentially interfering with the light radiation at the effective wavelength, are not transmitted to the optical acquisition system, so the image of the wrapping sheet on the supporting device is advantageously clear and well defined.

[0059] In one or more embodiments, the supporting device comprises a plurality of through holes extending from the first surface to the second surface.

[0060] In one or more embodiments, the apparatus comprises a suction system connected to the supporting device. Preferably the suction system is configured to suck air through one or more through holes of the plurality of through holes and hold the sheet on the supporting device.

[0061] Preferably the method comprises the step of activating the suction system connected to the supporting device, in particular to suck air through one or more through holes of the plurality of through holes, in order to hold the sheet on the supporting device. In this way it is possible to create a simple, effective and economical system for holding the wrapping sheet.

[0062] Preferably, the suction system comprises a suction pump and a suction chamber connected to the suction pump. Preferably, the suction system is connected to the supporting device through the suction chamber. In a more preferred manner, the suction system is connected to the supporting device through an upper wall of the suction chamber. Preferably the upper wall is provided with a plurality of suction openings. Preferably the upper wall is transparent to the visible light, namely transparent to the human eye, in order to allow the viewing of the content of the suction chamber. This way it can be checked that all the components inside the suction chamber are positioned and working correctly.

[0063] In one or more embodiments, the lighting system is located inside the suction chamber. Preferably, the upper wall is transparent to the wavelength working range, in particular to transmit a component of the light radiation having effective wavelength that belongs to the wavelength working range. In this way the light radiation having one or more effective wavelengths that belong to the wavelength working range is transmitted by the lighting system located inside the suction chamber substantially without attenuation through the upper wall. In this way, the background against which the outline of the covering sheet seen by the optical acquisition system stands out is particularly clear, for example bright or white, and therefore in clear contrast to that outline.

[0064] In one or more embodiments, the supporting device is movable.

[0065] Preferably, the supporting device can be driven, in particular to move the sheet in a forwarding direction. Preferably, the supporting device is one of a slat conveyor and a conveyor belt. In one or more embodiments, the apparatus comprises a drive unit connected to the supporting device, in particular to drive the supporting device.

[0066] Preferably the method comprises the step of driving the supporting device to position between the lighting system and the optical acquisition system the sheet placed on the supporting device.

[0067] Preferably, the method comprises the step of driving the supporting device to move the box joined to the sheet toward the wrapping station. In this way, the movement of the box joined to the wrapping sheet towards the wrapping station is carried out by this supporting device and is advantageously easy and effective.

[0068] In an alternative and equally preferred manner, the method comprises the step of picking by means of the transfer system the box joined to the sheet, in particular to move the box joined to the sheet from the supporting device to the wrapping station. In this way the wrapping station can be located in any position of the wrapping apparatus, in particular relative to the positioning equipment, since the transfer system is able to move in many directions, quickly and easily, the box joined to the wrapping sheet. In addition, thanks to the aforementioned transfer system, the movement speed of the box joined to the sheet towards the wrapping station is independent of the operating speed of the positioning equipment.

[0069] In one or more embodiments, the wrapping sheet comprises a main wall. Preferably the main wall defines the junction area of the wrapping sheet.

[0070] In one or more embodiments, the wrapping sheet comprises a plurality of panels.

[0071] Preferably the panels are connected to the junction area and foldable relative to the junction area.

[0072] In one or more embodiments, the wrapping sheet comprises a plurality of fold-over flaps. Preferably, each fold-over flap is connected to one of the panels and foldable relative to it.

[0073] In one or more embodiments, said at least one portion of sheet, an image of which is captured, comprises respective portions of two panels. In one or more embodiments, said at least one portion of sheet, an image of which is captured, comprises one of the fold-over flaps.

[0074] By appropriately selecting the portion of the sheet to capture the image of, it is possible to identify at least one exact point of the junction area in the captured image of the wrapping sheet, for instance the common point among two panels and the junction area or the common point among the junction area, a first panel and the fold-over flap of a second panel adjacent to the first panel. As a function of the exact point identified, the coupling of the box on the sheep occurs in a quick and exact way.

[0075] In one or more embodiments, the apparatus comprises a glue application device.

[0076] In one or more embodiments, the method comprises the step of applying an adhesive element on at least one portion of the wrapping sheet. Preferably, the adhesive element is one of a hot- melt glue, a cold glue, a vinyl glue, a cold vinyl glue, an animal glue.

[0077] Preferably, the adhesive element is applied on the junction area and on at least one of the panels and the flaps of the wrapping sheet.

[0078] In one or more embodiments, the lighting system comprises a plurality of light sources. Preferably, the lighting system comprises a matrix of light sources. Preferably, the lighting system comprises a light source having at least one of a LED emitter, an incandescent emitter and a fluorescent emitter.

[0079] Preferably, the light sources are movable relative to the supporting device independently of one another. In an equally preferred manner, the light sources are operable independently of one another.

[0080] Preferably, the method comprises the step of collecting at least one dimension of the supporting area.

[0081] In one or more embodiments, the method comprises the step of moving at least one of light sources as a function of said at least one dimension collected. In this way the area illuminated by the light radiation transmitted by the lighting system is optimized according to the size of the supporting area, in a simple and effective way.

[0082] In one or more embodiments, the method comprises the step of electing and activating a selection of the light sources as a function of said at least one dimension collected. In this way the area illuminated by the light radiation transmitted by the lighting system is optimized according to the size of the supporting area, with significant and advantageous energy savings due to the fact that the light sources intended to illuminate areas of the supporting device far from the one shot by the optical acquisition system are kept inactive.

[0083] It should be noted that some steps of the method described above may be independent of the specified order of execution, unless a sequence or contemporaneity between two or more steps is expressly indicated as necessary. Furthermore, some steps may be optional. Furthermore, some steps may be performed repetitively, or may be performed in series or in parallel with other steps of the method.

[0084] The features and advantages of the invention will become more apparent from the following detailed description of a preferred embodiment, illustrated by way of non-limiting example with reference to the accompanying drawings, in which: figure l is a top perspective view of a box to be wrapped and a wrapping sheet; figure 2 is a top view of the wrapping sheet of figure 1; figure 3 is a lateral schematic view of a part of the apparatus for wrapping a box with a wrapping sheet according to the present invention; figure 4 is a top view of a component of the apparatus according to the present invention; figure 5 is a top perspective schematic view of a further component of the apparatus according to the present invention; figure 6 is an exemplary representation of an image captured by an optical acquisition system of the apparatus according to the present invention; figure 7 is a diagram showing an example of emission spectrum of a lighting system of the apparatus according to the present invention. Figure 1 illustrates a box 100 to be wrapped, e.g. made of cardboard, having a rectangular base 101 and four lateral walls 102. The lateral walls 102 are connected both to the base 101 and to one another.

[0085] Figure 1 also illustrates a wrapping sheet 200 with known geometry (that is shape and extension), with a main wall that defines a junction area 201 having an inner surface 211 and an outer surface (the latter, not visible in figure) opposed to each other. The sheet 200 also comprises four panels 202 connected to the junction area 201 and foldable relative to it, and four fold-over flaps 203. Each fold-over flap of the fold-over flaps 203 is connected to one of the panels 202 and foldable relative to it, in particular two fold-over flaps 203 are connected to one single panel 202 (the lower horizontal panel, in figure 1) and two further fold-over flaps 203 are connected to another single panel 202 (the upper horizontal panel, in figure 1). The totality of the free sides of the panels 202 and of the fold-over flaps 203 of the sheet 200 constitutes a contour line or outline 240 of the sheet 200.

[0086] The junction area 201, one panel 202 (the left oblique panel, in figure 1) and one fold-over flap 203 immediately next to said panel 202 but not connected to it (the bottom left fold-over flap, in figure 1) intersect in a common point P that lies on the outline 240.

[0087] An apparatus for wrapping the cardboard box 100 with the wrapping sheet 200 comprises a gluing equipment (of a known type and not shown in the figures) to apply an adhesive element, for instance hot-melt glue, on the wrapping sheet 200. With specific reference to the example illustrated in figure 2, the wrapping sheet 200 coming out from the gluing equipment shows adhesive inserts 300 of hot-melt glue selectively dropped on the wrapping sheet 200 inner surface 211.

[0088] The apparatus according to the present invention comprises a lighting system 20 adapted to transmit a light radiation Bl, an optical acquisition system 30 adapted to receive said light radiation Bl, and a supporting device 10 intended to support the wrapping sheet 200 and operable to move said sheet 200 in a forwarding direction F. The lighting system 20 comprises a plurality of light sources 21, for instance a matrix of light sources 21, that are able to transmit a light beam B inside a wavelength base range A comprised between a minimum base wavelength LI and a maximum base wavelength L2. Inside the base range A, there is a wavelength working range comprised between a minimum working wavelength wl and a maximum working wavelength w2. The light radiation Bl is characterized by an effective wavelength wB which belongs to the working range . In the embodiment object of the present invention, the base range A corresponds to the infrared band, with minimum base wavelength LI equal to 780 nm and maximum base wavelength L2 equal to 1 mm, the working range is comprised between the minimum working wavelength wl equal to 870 nm and the maximum working wavelength w2 equal to 1300 nm, and the light radiation Bl has effective wavelength wB equal to 940 nm.

[0089] In the illustrated example, an optical filtering device 50 is placed downstream the light sources 21 with reference to the propagation direction of the light beam B. The optical filtering device 50 is able to filter and block the transmission of light beam B components that have respective wavelength that do not belong to the wavelength working range and potentially interfering with the light radiation Bl, for instance components having respective wavelengths lower than the minimum working wavelength wl, preferably comprised between the minimum base wavelength LI and the minimum working wavelength wl, and components having respective wavelengths higher than the maximum working wavelength w2, preferably comprised between the maximum working wavelength w2 and the maximum base wavelength L2.

[0090] The supporting device 10 is arranged between the lighting system 20 and the optical acquisition system 30 and is at least partially transparent to the light radiation BL In particular, the supporting device 10 is a movable conveyor belt, having any color, comprising a prime zone 14 transparent to the wavelength working range .

[0091] The conveyor belt 10 has a first surface 11, a second surface 12 opposed to the first surface 11, and a plurality of through holes 13 extending from the first surface 11 to the second surface 12. The first surface 11 is intended to receive the wrapping sheet 200, in particular at a supporting area 120 defined where there is a contact with the outer surface of said wrapping sheet 200.

[0092] The supporting area 120 has a respective perimeter edge 121, adjacent to a free area 220 defined on the first surface 11 where there is no contact with the wrapping sheet 200.

[0093] The supporting area 120 and at least part of the free area 220 are inside the prime zone 14.

[0094] The optical acquisition system 30 is directed toward the conveyor belt 10 and shoot a shooting area 15 (delimited with a dotted line in figure 4) of the first surface 11 of the conveyor belt 10, this shooting area 15 being entirely contained inside the prime zone 14.

[0095] The optical acquisition system 30 can comprise for instance an infrared camera able to receive the light radiation Bl, possibly also a receiving optical filter which is able to filter and block the transmission of ambient light components having respective wavelengths that do not belong to the wavelength working range and potentially interfering with the light radiation Bl.

[0096] The apparatus according to the present invention also comprises a suction system 60 with a suction pump 61 and a suction chamber 62. The suction chamber 62 is connected to the suction pump 61 and comprises an upper wall 620 provided with a plurality of through suction openings 621. The upper wall 620 is transparent to the wavelength working range .

[0097] The suction system 60 is connected to the conveyor belt 10 by means of the upper wall 620 of the suction chamber 62 and the suction openings 621 allow the air to be sucked by one or more through holes 13 of the conveyor belt 10 so that the sheet 200 is held on the conveyor belt 10.

[0098] In the illustrated embodiment, the lighting system 20 and the optical filtering device 50 are located inside the suction chamber 62, to the advantage of the compactness of the apparatus and without precluding its efficiency, thanks to the transparency of the upper wall 620 which allows the transmission of the light radiation Bl towards the optical acquisition system 30, substantially without attenuations.

[0099] The apparatus according to the present invention further comprises a transfer system 40 and a wrapping station 90. The transfer system 40 comprises for instance a robotic arm, a gripper or suction cups, preferably to position the box 100 to be wrapped on the sheet 200, to join the box 100 and the sheet 200, preferably to move the box 100 joined to the wrapping sheet 200 from the conveyor belt 10 to the wrapping station 90.

[0100] A processing and control unit 70 of the apparatus according to the present invention is connected to the gluing equipment, to the conveyor belt 10 (or to a drive unit, not shown in figure and connected to the conveyor belt 10 to drive the latter), to the lighting system 20, to the optical acquisition system 30, to the transfer system 40, to the suction system and to the wrapping station 90, to send control signals to each of them and receive respective data from each of them.

[0101] When the apparatus operates, the lighting system 20, opportunely activated by the processing and control unit 70, emits inside the suction chamber 62 the light beam B within the wavelengths base range A. The light beam B passes through the optical filtering device 50 which filters the light beam B components having respective wavelengths that do not belong to the working range di wavelengths. Hence, the optical filtering device 50 transmits only the radiations that belong to the wavelengths working range , comprising the light radiation Bl.

[0102] The light radiation Bl that comes out from the optical filtering device 50 then passes, substantially without attenuation, through the upper wall 620 of the suction chamber 62, which is transparent to the wavelengths working range .

[0103] To wrap a box 100, a wrapping sheet 200, having a known geometry stored in the processing and control unit 70, is placed on the conveyor belt 10 at the prime zone 14, so as to define inside the prime zone 14 the supporting area 120 in contact with the sheet 200 and the free area 220 not in contact with the sheet 200 on the first surface 11 of the conveyor belt 10. The supporting area 120 has a respective perimeter edge 121 adjacent to the free area 220. The perimeter edge 121 of the supporting area 120 is in contact with the outline 240 of the sheet 200.

[0104] The suction pump 61 is activated by the processing and control unit 70 to suck air through the suction chamber 62. In turn, the suction chamber 62 sucks air through the suction openings 621 of the upper wall 620 and from one or more through holes 13 of the conveyor belt 10, so as to hold the sheet 200 on the conveyor belt 10.

[0105] Having the wrapping sheet 200 firmly held on the conveyor belt 10, the gluing equipment (not shown) driven by the processing and control unit 70 drops an adhesive element, e.g. hot- melt glue, selectively on the inner surface 211 of the sheet 200, so has to have a pre-glued sheet 200.

[0106] The conveyor belt 10 (or the drive unit connected to it) is controlled by the processing and control unit 70 and driven to position between the lighting system 20 and the optical acquisition system 30 the pre-glued sheet 200 placed on the supporting device 10 at the prime zone 14. For instance, both a portion 250 (delimited by a dash-dot line in figure 2) of the preglued sheet 200, this portion 250 being in contact with a main section 125 of the supporting area 120, and a secondary section 225 of the free area 220 are shot in the shooting area 15.

[0107] The portion 250 comprises part of the junction area 201, a fold-over flap 203, part of two panels 202 and a segment 241 of the outline 240 of the pre-glued sheet 200. In particular, the segment 241 is in contact with a piece 122 of the perimeter edge 121 of the supporting area 120 and comprises the common point P where the junction area 201, one of the two panels 202 and the fold-over flap 203 intersect.

[0108] Since the prime zone 14 is transparent to the wavelength working range , the light radiation Bl passing through the prime zone 14 of the conveyor belt 10 at the free area 220 and in particular at its secondary section 225, not in contact with the sheet 200, reaches the optical acquisition system 30 substantially without attenuation. On the contrary, the light radiation Bl passing through the prime zone 14 of the conveyor belt 10 at the supporting area 120 and in particular at its main section 125, in contact with the sheet 200, is substantially totally absorbed by the sheet 200 itself and does not reach the optical acquisition system 30 at all.

[0109] Therefore, the optical acquisition system 30 captures a backlit image I of the portion 250 of the pre-glued sheet 200, placed on the conveyor belt 10.

[0110] The image I captured by the optical acquisition system 30 contains a clear and substantially uniform cutout, with low light intensity, representative of the portion 250 of the sheet 200, which stands out against a background which is also substantially uniform but with high light intensity, corresponding to the secondary section 225 of the free area 220.

[0111] The image I captured by the optical acquisition system 30 is then a substantially binary value. The cutout of the portion 250 of the wrapping sheet 200 seen by the optical acquisition system 30 turns out to be in contrast and clearly visible compared to the free area 220 of the conveyor belt 10, regardless of the colour of the inner surface 211 of the wrapping sheet 200 and of the colour of the conveyor belt 10.

[0112] In addition, since the portion 250 of the wrapping sheet 200 seen by the optical acquisition system 30 is in the shade relative to the optical acquisition system 30, there is no direct light or ambient light reflecting on the portion 250 of the wrapping sheet and so no glare phenomena of the optical acquisition system occur.

[0113] Advantageously, the present invention is not influenced by ambient light and minimizes, in some cases eliminates, the need to perform light correction cycles.

[0114] The processing and control unit 70 receives from the optical acquisition system 30 the captured image I and, in this image I, it identifies a shadow region R1 having low light intensity or a first light intensity LI, and a light region R2 adjacent to the shadow region R1 and having high light intensity or a second light intensity L2 higher than the first light intensity LI. As an alternative the processing and control unit 70 can identify, in the imagine I, a shadow region R1 having light intensity lower than or equal to the first light intensity LI, and a light region R2 adjacent to the shadow region R1 and having light intensity higher than the second light intensity L2, where the second light intensity L2 is higher than the first light intensity LI.

[0115] The shadow region R1 has a respective shadow outline R12 adjacent to the light region R2. The shadow outline R12 of the shadow region R1 is visible in the image I captured by the optical acquisition system 30 and is representative of the piece 122 of the perimeter edge 121 of the supporting area 120 in contact with the segment 241 of the outline 240 of the pre-glued sheet 200.

[0116] As a function of the shadow region R1 and of the light region R2 identified in the captured imagine I, the processing and control unit 70 detects the piece 122 of the perimeter edge 121 on the first surface 11 of the conveyor belt 10.

[0117] As a function of the piece 122, the processing and control unit 70 also detects the segment 241 of the outline 240 of the pre-glued sheet 200 and the common point P and, since the wrapping sheet 200 has a known geometry stored in the processing and control unit 70, the processing and control unit 70is able to define on the sheet 200 the junction area 201, in particular its location and orientation on the conveyor belt 10.

[0118] The processing and control unit 70 activate and control the transfer system 40 to pick the box 100 to be wrapped and, as a function of the acquired image I, positioning the box 100 on the wrapping sheet 200. In more details, as a function of the junction area 201 defined above, the transfer system 40 shifts the box 100 to bring it close to the position of the junction area 201 and rotates the box 100 so that the base 101 of the box 100 is correctly oriented to be entirely positioned into the junction area 201. Then the transfer system 40 further shifts the box 100 in order that the base 101 of the box 100 is in contact with the junction area 201 of the wrapping sheet 200. As a result the box 100 is joined to the sheet 200.

[0119] In the end, with reference to the illustrated example, the transfer system 40 driven by the processing and control unit 70 picks the box 100 joined to the wrapping sheet 200 and move them from the supporting device 10 to the wrapping station 90.

Claims

CLAIMS1. Method for wrapping a box with a wrapping sheet, the method comprising the following steps:- arranging a supporting device (10) having a first surface (11) and a second surface (12) opposed to each other;- placing a wrapping sheet (200) on said supporting device (10) to define, on said first surface (11), a supporting area (120) in contact with said sheet (200) and a free area (220) not in contact with said sheet (200), said supporting area (120) having a respective perimeter edge (121) adjacent to said free area (220);- transmitting a light radiation (Bl) from a lighting system (20) to an optical acquisition system (30), said light radiation (Bl) having at least an effective wavelength (wB) inside the infrared band, said supporting device (10) being at least partially transparent to said light radiation (Bl);- positioning between said lighting system (20) and said optical acquisition system (30) said sheet (200) placed on said supporting device (10), to prevent that part of said light radiation (Bl) is transmitted from said lighting system (20) to said optical acquisition system (30);- capturing by means of said optical acquisition system (30) an image (I) of at least one portion (250) of said sheet (200) placed on said supporting device (10);- as a function of said captured image (I), positioning a box (100) to be wrapped on said sheet (200), to join said box (100) and said sheet (200);- moving said box (100) joined to said sheet (200) to a wrapping station (90).

2. Method according to claim 1, further comprising the steps of:- identifying, in said captured image (I), a shadow region (Rl) having a first light intensity (LI), and a light region (R2) adjacent to said shadow region (Rl) and having a second light intensity (L2) higher than said first light intensity (LI);- locating, on said first surface (11) of said supporting device (10), at least a piece (122) of said perimeter edge (121) of said supporting area (120), as a function of said shadow region (Rl) and light region (R2) identified in said captured image (I);- defining, on said sheet (200), a junction area (201) as a function of said piece (122); said positioning a box (100) to be wrapped on said sheet (200) being carried out as a function of said junction area (201).

3. Method according to claim 2, wherein said box (100) comprises a base (101) and a plurality of lateral walls (102) connected to said base (101), said positioning comprising at least one between shifting said box (100) and rotating said box (100), so that said base (101) is entirely positioned into said junction area (201).

4. Method according to any preceding claim, wherein said lighting system (20) transmits a light beam (B) inside a wavelength base range (A), said effective wavelength (wB) belonging to a wavelength working range (Q) included inside said wavelength base range (A), and wherein said supporting device (10) comprises a prime zone (14) transparent to said wavelength working range (Q), the method comprising positioning between said lighting system (20) and said optical acquisition system (30) said sheet (200) placed on said supporting device (10) at said prime zone (14).

5. Method according to claim 4, further comprising filtering by means of an optical filtering device (50) components of said light beam (B) having respective wavelengths that do not belong to said wavelength working range (Q).

6. Method according to any preceding claim, wherein said supporting device (10) comprises a plurality of through holes (13) extending from said first surface (11) to said second surface (12), the method further comprising activating a suction system (60) connected to said supporting device (10) to suck air through one or more through holes (13) of said plurality of through holes (13), in order to hold said sheet (200) on said supporting device7. Method according to any preceding claim, wherein said supporting device (10) is movable, the method further comprising driving said supporting device (10) to position said sheet (200) placed on said supporting device (10) between said lighting system (20) and said optical acquisition system (30).

8. Method according to any preceding claim, further comprising picking by means of a transfer system (40) said box (100) joined to said sheet (200), to move said box (100) joined to said sheet (200) from said supporting device (10) to said wrapping station (90).

9. Method according to any preceding claim, wherein said wrapping sheet (200) comprises a junction area (201) and a plurality of panels (202) connected to said junction area (201) and foldable relative to said junction area (201), and wherein said at least one portion (250) of said sheet (200), an image (I) of which is captured, comprises respective portions of two of said panels (202).

10. Method according to claim 9, wherein said wrapping sheet (200) comprises a plurality of fold-over flaps (203), each fold-over flap (203) being connected to one of said panels (202) and foldable relative to it, and wherein said at least one portion (250) of said sheet (200), an image (I) of which is captured, comprises one of said fold-over flaps (203).

11. Method according to any preceding claim, wherein said lighting system (20) comprises a plurality of light sources (21) movable relative to said supporting device (10) independently of one another, the method further comprising the steps of:- collecting at least one dimension of said supporting area (120);- moving at least one of said light sources (21) as a function of said at least one dimension collected.

12. Method according to any preceding claim, wherein said lighting system (20) comprises a plurality of light sources (21) operable independently of one another, the method further comprising the steps of:- collecting at least one dimension of said supporting area (120);- electing and activating a selection of said light sources (21) as a function of said at least one dimension collected.

13. Apparatus for wrapping a cardboard box (100) with a wrapping sheet (200), said apparatus comprising:- a lighting system (20) adapted to transmit a light radiation (Bl) having at least an effective wavelength (wB) inside the infrared band;- an optical acquisition system (30) adapted to receive said light radiation (Bl);- a supporting device (10) placed between said lighting system (20) and optical acquisition system (30), said supporting device (10) being at least partially transparent to said light radiation (Bl) and intended to support said wrapping sheet (200).

14. Apparatus according to claim 13, wherein said supporting device (10) is operable to move said sheet (200) in a forwarding direction (F).

15. Apparatus according to claim 13 or 14, further comprising a suction system (60) connected to said supporting device (10), said supporting device (10) comprising a plurality of through holes (13), said suction system (60) being configured to suck air through one or more through holes (13) of said plurality of through holes (13) and hold said sheet (200) on said supporting device (10).

16. Apparatus according to claim 15, wherein said suction system (60) comprises a suction pump (61) and a suction chamber (62) connected to said suction pump (61), said suction system (60) being connected to said supporting device (10) through said suction chamber (62), and wherein said lighting system (20) is positioned inside said suction chamber (62).

17. Apparatus according to any claim 13 to 16, wherein said lighting system (20) comprises a plurality of light sources (21), said light sources (21) being movable relative to said supporting device (10) independently of one another, or operable independently of one another.

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