Packaging machine with sealant dispensing device

Abstract

A packaging machine for packaging household paper products, such as kitchen tissues and toilet rolls, by wrapping paper wrapping sheets around the products, the packaging machine comprising: a feeding station for continuously feeding product groups, including at least one product, one by one; a wrapping station for wrapping a paper wrapping sheet around the product group; a sealing device for sealing the paper wrapping sheet around the product group; a wrapping sheet supply station for supplying one wrapping sheet at a time towards the wrapping station along a sheet supply direction, comprising a dispensing device for applying a sealant to the paper wrapping sheet.

Description

Technical Field

[0001] The present invention relates to a packaging machine for paper products for household use; more specifically, the object of the present invention is a packaging machine for products (such as rolls of kitchen paper and toilet paper) wrapped in sheets of paper. Background Art

[0002] In the paper industry, paper products (especially rolls of toilet paper and kitchen paper) are usually wrapped in sheets of thermoplastic film, or in the case of a single roll, in a sheet of paper. The packaging containing a single roll is usually used for rolls of toilet paper, while the multi-roll packaging wrapped in a heat-sealable film is used for both rolls of toilet paper and kitchen paper. Generally, the single-roll packaging wrapped in paper film is not sealed, while the larger packaging wrapped in thermoplastic film is heat-sealed.

[0003] To manufacture these packages, the packaging machine has a conveyor which, in the case of multi-roll packaging, feeds rows of rolls arranged coaxially with respect to a horizontal axis to a station for grouping the rolls and forming groups of rolls arranged side by side in one or more layers. Then, the group of rolls is conveyed to a vertically moving elevator which lifts each group of rolls to a wrapping station. The wrapping station wraps the group of rolls in a wrapping film, thus completing the packaging of the rolls. An example of such a packaging machine is disclosed in patent documents WO2009060490 and EP12289669B1. This type of packaging is called primary packaging and is usually used for retail. The resulting packages are conveyed to secondary packaging where the packages are grouped and placed in large plastic bags. Examples of these packaging machines are disclosed in EP1442984, EP1771335. Finally, the bags containing the packages are placed on pallets and then sent to a warehouse or directly to wholesalers.

[0004] Generally, the group of rolls is packaged by wrapping a thermoplastic wrapping film (such as polyethylene or other synthetic polymers) around the group of rolls; wrapping the group of rolls around four sides and forming a kind of parallelepiped with rectangular faces open at two opposite sides. Then, the side flaps of the sheets protruding from the two sides are folded, thus completing the covering of the rolls. Finally, the creases of the thermoplastic film are stabilized by a heat seal made of a conveyor belt coated with Teflon after heating, as shown, for example, in EP1381543B1. In the case of packaging a single roll with a sheet of paper, the conveyor belt coated with Teflon after heating thermally activates an adhesive with which the entire surface of the sheet of paper is pre-treated.

[0005] One of the main drawbacks of the prior art systems is the use of a heated PTFE-coated conveyor belt, which is known to have poor energy efficiency due to resistance heating. In addition, the service life of the PTFE-coated conveyor belt is very short as it needs to be replaced frequently. The rapid wear of the PTFE-coated conveyor belt also causes significant variations in production as the efficiency of the conveyor belt drops sharply within a short period, resulting in a large amount of production waste. Moreover, in the case of packaging with paper sheets, the PTFE-coated conveyor belt cannot effectively transfer heat to the glue that should be reactivated; thus, in order to achieve a sufficient seal, the machine speed must be reduced, leading to a decrease in productivity. As an alternative, it is necessary to heat the conveyor belt more, resulting in further shortening its service life and consuming more energy. Another drawback of the PTFE-coated conveyor belt is that it cannot provide a uniform and sufficiently rigid contrast surface for the rolls to seal the creases of the wrapping sheets.

[0006] Despite the significant problems associated with using paper sheets instead of traditional thermoplastic films, the growing environmental awareness is increasingly driving the paper industry to use natural and recyclable materials (such as paper) to replace fossil-based materials (such as general plastic heat-sealable films or synthetic films). Summary of the Invention

[0007] An object of the present invention is to provide a machine for packaging products made of tissue paper or non-woven fabric, such as rolls of kitchen paper towels and toilet paper, napkins, handkerchiefs, wet wipes, and interleaved folded products, which can overcome the current limitations in using paper wrapping materials. More specifically, an object of the present invention is to provide a packaging machine for tissue paper products that is adapted to make the packaging more environmentally friendly and efficient while ensuring the flexibility of the packaging and the quality of the produced packages.

[0008] Another object of the present invention is to provide a packaging machine for packaging rolls and / or other paper products that uses more green and environmentally friendly packaging materials (such as paper) and overcomes all of the above drawbacks.

[0009] Another object of the present invention is to provide a packaging machine for tissue paper products (such as crepe paper and non-woven fabric products) that significantly reduces the use of glue or other sealants compared to the prior art.

[0010] These and other objects are achieved by a packaging machine for packaging paper products, which comprises:

[0011] o A supply station for successively supplying, one by one, a product group including at least one product;

[0012] o A wrapping station for wrapping a paper wrapping sheet around the product group;

[0013] o A sealing device for sealing the paper wrapping sheet around the product group;

[0014] o A wrapping sheet supply station for supplying, one by one, paper wrapping sheets along a sheet supply direction towards the wrapping station, including a dispensing device for applying a sealant to the paper wrapping sheets.

[0015] Each product group consists of at least one product and is wrapped in a single paper wrapping sheet.

[0016] In a preferred embodiment of the present invention, the wrapping sheet supply station is arranged upstream of the wrapping station along the sheet supply direction.

[0017] The wrapping sheet supply station for supplying the paper wrapping sheets to the supply station may include a cutting unit and an unwinding device. The cutting unit is for cutting individual paper wrapping sheets from a web material unwound from a reel, and the unwinding device is for unwinding the web material reel towards the cutting unit. The web material substantially corresponds to a continuous sequence of (actual) paper wrapping sheets divided by the cutting unit. Thus, in this document, the term "paper wrapping sheet" or "paper sheet" or "wrapping sheet" may also be used when referring to the web material around the wrapping sheet, unless referring to an individual paper sheet.

[0018] If the individual paper sheets are made of a paper web material unwound from a reel, the dispensing device may be positioned upstream or downstream of the cutting unit along the sheet supply direction, so that the sealant can be applied to the web material or to the individual sheets that have been cut.

[0019] The paper wrapping sheet (either individually or actually arranged in the web material) is defined by two parallel side edges and two side edges transverse to the sheet supply direction towards the wrapping station. When the sheet is cut from the web material, the side edges transverse to the sheet supply direction are obtained by cutting the web material.

[0020] The sealant is dispensed from the dispensing device, which includes at least one dispenser configured to:

[0021] o When the dispensing device is arranged upstream of the cutting unit, apply a line of sealant to an area of the web material corresponding to the paper wrapping sheet in a direction parallel to one of the two side edges parallel to the sheet supply direction, and the dispensing device includes at least one dispenser for applying a line of sealant in a direction parallel to each of the two side edges transverse to the sheet supply direction;

[0022] o When the dispensing device is arranged downstream of the cutting unit, a sealant line is applied to the single paper-wrapped sheet in a direction parallel to one of the two side edges parallel to the sheet supply direction, and the dispensing device includes at least one dispenser for applying a sealant line in a direction parallel to each of the two side edges transverse to the sheet supply direction.

[0023] These lines are continuous or discontinuous, and their length is equal to or less than the length of the corresponding side edge of the paper-wrapped sheet.

[0024] For example, the line can also be formed by several regions adjacent to each other along the line (each region is in contact with or very close to the adjacent region, for example, the distance is less than 10 mm). For example, the first region of the line can be achieved by a first dispenser applying sealant according to a first direction (for example, consistent with the sheet / web supply direction), and the second region adjacent to the first region is achieved by a second dispenser adjacent to the first dispenser and applying sealant according to the same first direction; the second dispenser is adjacent to the first dispenser according to a second direction opposite to the first direction (for example, orthogonal to the sheet / web material supply direction). In practice, the width of each region (for example, measured according to the direction orthogonal to the sheet / web material supply direction) is equal to the operating width of the dispenser, and the height (orthogonal to the width) is the result of the activation time of the dispenser on the moving sheet / web material: thus, the line is a set of these regions achieved by adjacent dispensers. Another line orthogonal to the above line and corresponding to the sum of the adjacent regions formed by each dispenser can be achieved, for example, according to a direction parallel to the sheet / web material supply direction, and its width is, for example, equal to the operating width of the dispenser. In this case, the height of the line is longer than the height of the line in the above example, and is achieved by the activation time of the dispenser on the moving sheet / web material being longer than that in the previous example.

[0025] These lines are provided on the paper-wrapped sheet at a distance between 0.5 mm and 50 mm, preferably between 1 mm and 25 mm, from the corresponding side edge or edge of the paper-wrapped sheet.

[0026] Advantageously, the dispenser used is of the coating type, or more generally, is a contact type for contacting the paper-wrapped sheet, for example, applying pressure to the paper-wrapped sheet. In other less preferred embodiments, other types of dispensers can be used, such as nozzles.

[0027] To improve the efficiency and productivity of the packaging machine, the dispensing device includes means for adjusting the height distance of the dispenser from the paper-wrapped sheet, and means for laterally adjusting the dispenser relative to the sheet supply direction.

[0028] According to a preferred embodiment, the dispensing device includes at least three dispensers.

[0029] Preferably, the dispensing device includes at least three dispensing units, at least two of which include a plurality of dispensers.

[0030] Preferably, the dispensers are aligned along a line orthogonal to the supply direction of the web material, and the dispensers are preferably translatable orthogonally to the supply direction.

[0031] The dispensing device is preferably associated with a sealant supply system.

[0032] Preferably, the supply system includes a valve for each dispenser, and the valve allows supply / non - supply to the corresponding dispenser.

[0033] Preferably, both the first dispensing unit and the second dispensing unit include a plurality of dispensers adjacent to each other along a line. The first unit is spaced apart from the second unit. The first unit and the second unit are adapted to dispense sealant within a first time interval, thereby creating two spaced - apart segments of a first sealant line, where each segment is formed by adjacent sealant regions, and where the third dispensing unit includes at least one dispenser adapted to dispense sealant within a second time interval longer than the first time interval, thereby creating a continuous sealant line orthogonal to the first line.

[0034] Preferably, the sealant supply system includes pumping means for supplying sealant to at least one dispenser, and the sealant supply rate varies depending on the supply speed of the web material onto which the sealant is to be applied or depending on the production speed of the packaging machine.

[0035] According to a preferred embodiment, the dispensing device is associated with a sealant supply device, which includes pumping means for supplying sealant to at least one dispenser, and the sealant supply rate can vary depending on the supply speed of the web material onto which the sealant is to be applied or depending on the production speed of the packaging machine.

[0036] The wrapper sheet supply station preferably includes detection means for detecting the position of the paper wrapper sheet along the sheet supply direction. The detection means for detecting the position of the paper wrapper sheet is preferably an encoder, although other suitable means can also be used.

[0037] A sensor is used to detect the position of the paper sheet or the position of the web material unwound from the reel, so that the dispensing device can apply the sealant in phase with the position of the wrapper sheet or the paper web material.

[0038] Preferably, the grammage of the paper wrapper sheet or the paper web material for realizing a single paper wrapper sheet is between 10 g / m 2 and 100 g / m2 between 10 μm and 500 μm in thickness.

[0039] Preferably, the dispensing device is adapted to dispense the sealant in such a way that the amount of sealant on each paper wrapping sheet is between 30% and 1% of the weight of the sheet, more preferably between 10% and 1% of the weight of the sheet, and even more preferably between 5% and 1% of the weight of the sheet.

[0040] Advantageously, the product supply station includes a lift for lifting the product group towards the wrapping station. During the lifting movement towards the wrapping station, the product group encounters a paper wrapping sheet arranged parallel to a plane transverse to the direction of group lifting. In this way, the paper wrapping sheet forms a partial wrap around the product group in the shape of an inverted "U".

[0041] The wrapping station includes a bottom folding device that can complete the partial inverted-U wrapping of the paper wrapping sheet around the product group, thereby forming a tubular structure or parallelepiped with an approximately rectangular face, open at two opposite parallel sides of the product group. Each of the two opposite parallel sides has a protruding hem that will be folded to complete the wrapping.

[0042] The crease under the product group formed by the bottom folding device is stabilized by a transverse sealing device.

[0043] To complete the packaging cycle, the wrapping station includes:

[0044] ο A bottom folding device for completing the partial wrapping of the wrapping sheet around the product group, forming a tubular structure open at opposite sides of the product group, the open tubular structure having hems of the wrapping sheet to be folded, the hems protruding from each of the two sides of the product group;

[0045] ο A front side folding device for each of the two sides of the product group to fold a part of the hem of the wrapping sheet against each side, thereby forming a front crease;

[0046] ο A rear side folding device for each of the two sides of the product group to fold a part of the hem of the wrapping sheet against each side, thereby forming a rear crease;

[0047] ο A top side folding device for each of the two sides of the product group to fold a part of the hem of the wrapping sheet against each side, thereby forming a top crease;

[0048] ο A bottom side folding device for each of the two sides of the product group to fold a part of the hem of the wrapping sheet against each side, thereby forming a bottom crease.

[0049] In some embodiments, the sealing station includes a supply channel and a pair of sealing members disposed opposite each other on both sides of the supply channel. Each sealing member preferably has a uniform sealing surface made of ferromagnetic material (or containing paramagnetic material) and is associated with a corresponding electromagnetic inductor. Preferably, each sealing member is driven between at least two return members. In other less efficient embodiments, the sealing members can be heated by other known methods (such as heat-resistant or infrared systems, etc.). These less efficient systems are typically associated with the use of a conveyor belt coated with polytetrafluoroethylene instead of ferromagnetic sealing members with a uniform surface.

[0050] In a further more preferred embodiment, at least one and preferably both of the pair of sealing members include a uniform flexible member of ferromagnetic material (or containing paramagnetic material). In this case, for example, the sealing member consists of a flexible ferromagnetic member having a uniform sealing surface.

[0051] The present invention also relates to a method of packaging a group of products with a paper-wrapped sheet, the products being, for example, toilet paper rolls, kitchen paper towels, napkins, handkerchiefs, and interleaved folded products, the method comprising the following steps:

[0052] o Continuously supplying one by one a group of products formed by at least one product;

[0053] o Supplying one by one paper-wrapped sheets along the sheet supply direction towards the wrapping station;

[0054] o Wrapping the paper-wrapped sheet around the group of products;

[0055] o Sealing the paper-wrapped sheet around the group of products;

[0056] o Preparing a wrapped sheet with a sealant and then wrapping the wrapped sheet around the group of products.

[0057] The described method can also prepare a paper-wrapped sheet with a sealant by means of at least one sealant dispenser.

[0058] The paper-wrapped sheet is preferably defined by two parallel side edges and two transverse side edges with respect to the sheet supply direction. The step of preparing a paper-wrapped sheet with a sealant provides for dispensing a line of sealant along one of the two side edges parallel to the sheet supply direction and a line of sealant along each of the two transverse side edges parallel to the sheet supply direction.

[0059] According to the method of the present invention, continuous or discontinuous lines can also be applied, the length of these lines being equal to or less than the length of the corresponding side edges of the paper-wrapped sheet, and these lines are preferably applied to the paper-wrapped sheet at a distance between 0.5 mm and 50 mm from the corresponding side edges.

[0060] If the individual paper-wrapped sheets are obtained from a web material unwound from a reel, the method includes using a cutting unit to cut the individual paper-wrapped sheets from the web material unwound from the reel.

[0061] In this case, the step of cutting the individual paper-wrapped sheets can occur before or after the step of preparing the paper-wrapped sheets with a sealant.

[0062] Advantageously, when required, the position of the wrapping sheet or the web material along the sheet supply direction can be determined, and then the sealant is applied, that is:

[0063] o when the step of cutting the wrapping sheet occurs before the step of preparing the paper-wrapped sheets with a sealant, the sealant is applied in coordination with the position of the wrapping sheet;

[0064] o when the step of cutting the wrapping sheet occurs after the step of preparing the paper-wrapped sheets with a sealant, the sealant is applied in coordination with the position of the web material.

[0065] In order to optimally seal the package, depending on the type and quality of the paper material or the individual sheet or web material, and / or depending on the specifications (format) of the package to be produced, the temperature of the heat-sealing surface should be between 100 °C and 400 °C.

[0066] In an improved embodiment, the supply channel of the sealing station includes a conveyor to move the product group forward along the sealing station in the product sealing direction. When the sealing member is power-driven, the product can move forward along the sealing station through the conveyor or the sealing member or both. In a configuration where the product group moves forward only through the sealing member, the conveyor can be replaced by a sliding surface.

[0067] To facilitate the forward movement of the product group leaving the wrapping station, the sealing station moves the product group forward at a speed higher than that of leaving the wrapping station.

[0068] To increase flexibility and productivity, the sealing station includes adjustment means for adjusting the mutual distance of the sealing members. The distance between the sealing surfaces can be adjusted, for example, according to the size of the product group.

[0069] Advantageously, the packaging machine includes an adjustment member for adjusting the sealing pressure.

[0070] To obtain more efficient heating, the inductor associated with each sealing element is supplied with an induction current having a frequency between 10 Hz and 500 kHz.

[0071] In this document, the term "uniform surface" refers to a surface that has no bumps, protrusions, depressions, or holes in the portion that comes into contact with the paper-wrapped sheet. For example, a uniform surface can be a smooth surface. Even more specifically, a smooth surface can be a surface that is smooth and continuous in the area that comes into contact with the roller set. Specifically, in this document, a "smooth surface" refers to a surface that cannot score the wrapping sheet during sealing (i.e., when the roller set is in contact with the sealing member with a certain pressure). A continuous sealing surface refers to a surface that comes into contact with the package to be sealed and has no discontinuous parts (i.e., edge regions, breaks, etc.).

[0072] For example, a uniform surface can be defined as a surface with a roughness less than 200 Ra. Therefore, when in contact with the package, the sealing surface should be a continuous surface with a roughness less than 200 Ra.

[0073] According to a preferred embodiment, the packaging machine includes a cooling device for cooling the sealant provided on the paper-wrapped sheet; the cooling device is preferably air-cooled and includes at least one air jet nozzle that is directed at the area occupied by at least one paper-wrapped sheet.

[0074] Preferably, the cooling device includes at least one air jet nozzle that is directed at a portion of the web material path that is downstream of the area where the sealant is applied and upstream of the cutting unit, preferably directed at the surface of the paper web material provided with the sealant.

[0075] Preferably, the cooling device is adapted to form a laminar air flow on the paper web material.

[0076] Preferably, the cooling device includes at least one surface that faces at least one portion of the web material path and, together with the web material, defines a channel for the air flow from at least one nozzle.

[0077] The nozzle is preferably a Coandă ( effect) nozzle. Description of the Drawings

[0078] The present invention will be better understood from the following description and drawings, which show non-limiting embodiments of the present invention. More specifically, in the drawings:

[0079] o Figure 1 is a schematic side view of a supply station for supplying a product (such as a roll) in a machine according to the present invention;

[0080] o Figure 2Schematic side view of a wrapping station in a machine according to the invention for wrapping a product (such as a roll);

[0081] o Figures 3 to 6 Shows the schematic sequence of lifting a product group and starting the wrapping of a wrapping sheet in the station of Figure 2 ;

[0082] o Figure 7A Schematic perspective view of a supply station in a machine according to the invention for supplying a wrapping sheet;

[0083] o Figure 7B Is Figure 7A Side view of the wrapping sheet supply station of

[0084] o Figure 8A Shows a first schematic view of a wrapping sheet supply station in a machine according to the invention, in which the direction of the sealant distribution system is different from Figure 7A the direction shown;

[0085] o Figure 8B Shows a first schematic view of a cooling device for cooling the sealant on a paper web / paper sheet, the cooling device being arranged along a linear part of the paper web path in a wrapping sheet supply station in a machine according to the invention;

[0086] o Figure 8C Shows a second schematic view of a cooling device for cooling the sealant on a paper web / sheet, the cooling device being arranged along several parts of the paper web path in different directions in a wrapping sheet supply station in a machine according to the invention;

[0087] o Figures 9A to 9G Shows the schematic sequence of folding a wrapping sheet with glue distribution around a product group;

[0088] o Figure 10 Shows a schematic view of the glue distribution on a wrapping sheet different from the previous figures;

[0089] o Figure 10A And Figure 10B Show respectively the schematic perspective view and top view of a package composed of a single-layer roll, the wrapping sheet having a glue distribution according to Figure 10 ;

[0090] o Figure 11A And Figure 11B Show respectively the schematic top view of a wrapping sheet with a glue distribution different from the previous figures, and the schematic view of the closed surface of a package with such a different glue distribution;

[0091] o Figure 12 Schematic isometric view of a sealing station of a machine according to the invention;

[0092] o Figure 13 is Figure 12 a schematic front view of a sealing station;

[0093] o Figure 14 is Figure 12 a schematic top view of a sealing station;

[0094] o Figure 15 is another schematic perspective view seen from the bottom of a sealing station of Figure 12 DETAILED DESCRIPTION

[0095] In Figure 1 a packaging machine 1 for packaging a product R, such as a paper roll, is shown. These rolls are made of tissue paper (such as toilet paper rolls or kitchen paper rolls). These rolls may have a cardboard core around which the tissue paper is wound, or they may not have a cardboard core, i.e., these rolls may be made of paper wound completely from the center to form a solid cylinder (so-called solid rolls), or they may have a cylindrical cavity, e.g., wound around a central hole in the absence of a core (so-called coreless rolls).

[0096] The packaging machine 1 is supplied by a product supply station 2, which may include a launching device 3 of a known type, such as that described in EP2763917B1. In this case, the launcher 3 includes one or more supply conveyors 4 that cooperate with a power-driven conveyor 5 that laterally engages the product R. In this particular case, the power-driven conveyor 5 is shown as being arranged laterally, but it should be understood that it may also be arranged in a different configuration, e.g., above and below the product R. The supply station 2 may consist of a plurality of supply channels arranged side by side, where each supply channel supplies a series of products R. The launcher 3 is controlled in such a way that a group G of products R (in this case rolls) is metered out successively towards a subsequent conveying member, which is also part of the supply station 2 for conveying the group G of products and will be described below.

[0097] ​In the example described, the launching device 3 successively meteredly distributes the groups G of product R onto the conveyor 7, which may have a sliding surface 8 (on which the groups G of product R slide) and a pair of flexible members 9 (such as chains), to which the pushers 10 are constrained. The pushers 10 are spaced apart to receive the groups G of product R and extend transversely to the supply direction of product R. Each pusher 10 is constrained to the flexible member 9 at its two ends. In this way, by appropriately moving the flexible member 9, the groups G of product R are moved forward, i.e., are pushed forward by the pushers 10 synchronously with the supply speed of the packaging machine 1. Then, the launching device 3 and the conveyor 7 are configured to group and meteredly distribute the groups G of product R of a desired size in a rhythmic manner.

[0098] The groups G of product R are conveyed from the conveyor 7 to the stratifying station 6, which is also part of the product supply station 2. The stratifying station 6 may include a conveyor 11, which has a swinging movement according to the double arrow f11 to distribute the individual groups G or layers of product R into the supply device 12. In this particular case, the supply device 12 includes two layers of product, but it should be understood that the stratification may have more than two layers of product, such as three layers or even more layers of product. If the packaging machine 1 is configured to produce single-layer packaging, the stratifying station 6 is clearly unnecessary.

[0099] The supply device 12 shown herein has pushing members for each product layer formed by a group G of individual products R. Similar to the conveyor 7, for each layer, the pushing members are respectively formed by sliding surfaces 13A, 13B and pushers 14A, 14B driven forward by corresponding flexible members 15A, 15B. The supply device 12 synchronously inserts each layer of product R onto the elevator 16. For example, the individual layers may be placed on the elevator 16 simultaneously or one by one.

[0100] Similar to the embodiment of the launcher 3 and the conveyor 7, this embodiment of the supply device 12 is given only as a non-limiting example, since completely different configurations may be used for grouping, meteredly distributing and stratifying the product.

[0101] The elevator 16 consists of a plate 16A, which receives and supports the groups G of the stratified product R and can move vertically along the lifting direction shown by the double arrow f16. The movement of the plate 16A can be achieved by a linkage crank-type mechanism (not shown in detail for simplicity) driven by a motor 17. Advantageously, the elevator 16 also includes a bottom stop 18, which can be adjusted along the double arrow f18 according to the length or depth of the groups G of product R. The depth of the groups G of product R may vary depending on the number of products R forming each column or depending on the length of the individual products R. As Figure 2As shown in the side view, the elevator 16 may further include side dams 21A, 21B, 21C, 21D disposed along two side flanks of the group G of products R to accommodate and accompany the group G of products R during lifting.

[0102] In the example shown, the launching device 3 groups two products R for each lane together with the conveyor 7, but it is obvious that a single product R or more than two products can also be grouped for each lane.

[0103] The elevator 16 sequentially lifts the group G of products R from the tiering height Qs to the wrapping height Qa of the wrapping station 19, which is arranged above the product supply station. During the lifting movement along the double arrow f16, the group G of products R encounters the paper wrapping sheet F arranged in a plane orthogonal to the lifting direction f16, and starts the wrapping cycle that will be described in more detail in Figures 3 to 6 . The paper wrapping sheet F is advantageously arranged at a horizontal level between the tiering height Qs and the wrapping height Qa.

[0104] The paper wrapping sheet F can be inserted into and positioned in the wrapping station 19 respectively through two openings 22 formed between the side dams 21A and 21C and between 21B and 21D, while being held at its two edges B1, B2 by the sheet supply member 20 (such as a conveyor belt). The formation of the paper wrapping sheet and its supply to the wrapping station 19 will be described in more detail below.

[0105] Now refer to Figures 3 to 6 and Figures 9A to 9G to describe the wrapping cycle. Specifically, Figure 3 shows the group G of products R arranged at the tiering height Qs. In Figure 4 , the group G of products R contacts the paper wrapping sheet F, and starts the wrapping of the paper wrapping sheet F around the top surface Fs and the side surface Fl of the group G of products R. In Figure 5 and Figure 9B , the group G of products R is at the wrapping height Qa, and is completely wrapped by the paper wrapping sheet around the top surface and the side surface, leaving two edges B1, B2 of the paper wrapping sheet F extending vertically downward, and if necessary, extending vertically downward with different lengths. At this time, the paper wrapping sheet partially wrapped around the group G of products R forms a shape similar to an inverted "U". Finally, in Figure 6 and Figure 9CIn it, the edges B1, B2 have been superposed on each other to complete the wrapping of the bottom surface of the group G of products R. The two edges B1, B2 have been superposed on each other by two bottom folding devices 25, 26, which are part of the wrapping station 2 and can be moved by their mutual movement along the respective arrows f25 and f26. Once the two edges B1 and B2 have been superposed on each other, while the group G of products R is supported by the movable bottom folding devices 25, 26, the elevator 16 can reverse the upward movement and descend back to the layering height Qs to receive a new group G of products R. At this time, as Figure 9C shown, the facing front Fa and back Fp of the group G of products R are free (exposed), and the side folds LI, L2 of the paper wrapping sheet F extend from the group G of products R substantially orthogonally to the front Fa and back Fp.

[0106] Then, the superposed edges B1, B2 are stabilized by a transverse sealing device 30, which is arranged downstream of the elevator along the wrapping direction fA. The transverse sealing device 30 can have an activation surface (i.e., heating surface), for example rectangular, coplanar with the sliding surface 23, the maximum dimension of which is orthogonal to the wrapping direction fA and faces the group G of products R. Preferably, the transverse sealing device 30 moves towards and away from the group G of products R orthogonally to the sliding surface 23 along the movement direction indicated by the double arrow f30. Specifically, when the transverse sealing device 30 has been brought to the group G of products R partially wrapped by the paper wrapping sheet F, it seals the package in the overlapping area of the edges B1, B2. The activation surface of the transverse sealing device 30 can be smooth or have a dotted texture and can be heated to a temperature between 100 °C and 350 °C. In some cases, the sealing of the overlapping edges B1 and B2 can occur when the group G of products R is stationary (i.e., it does not move forward along the wrapping direction fA), thus allowing the transverse sealing device 30 to remain in contact with the overlapping edges B1 and B2 for the necessary time. This allows the sealant S to be activated and seal (i.e., irreversibly enclose) the paper wrapping sheet F around the group G of products R, forming a tubular structure closed on the periphery, in contact with the side surfaces of the products R, and leaving at least partially protruding side folds L1 and L2 orthogonal to the side surfaces of the group G of products R, which will be described in more detail below.

[0107] In other cases, it is possible to make a transverse sealing device 30 perform, in addition to the movement orthogonal to the sliding surface 23, a movement parallel to the sliding surface 23 in order to seal the group G of products R while moving forward along the wrapping direction fA.

[0108] The lifting movement of the elevator 16 allows the group G of products R to be inserted at the wrapping height Qa into a space S having a width equal to or slightly less than the width of the group G of products R, which space is defined by the successive teeth 27.2 of a conveyor 27 forming part of the wrapping station 19. The conveyor 27 moves the group G of products R supported by the sliding surface 23 along the wrapping direction fA to effect the wrapping of the paper wrapping sheet F around the group G of products R. The teeth 27.2 are constrained to a flexible member 27.1 (such as a conveyor belt or a chain) which is driven between two pulleys 27.3, at least one of which is power-driven, so that the teeth 27.2 move along a closed path, the active branch of which (i.e., the branch where the wrapping of the paper wrapping sheet F is effected) is the lower branch.

[0109] The conveyor 27 can also be implemented in a different way. For example, the teeth 27.2 can be transported by carriages movable along guides. A linear motor controlled to receive and convey the group G of products R can be associated with each carriage. An example of such a conveyor 13 is described in IT1426528.

[0110] In other embodiments, the conveyor 27 can be configured, for example, to constrain the successive teeth 27.2 to a plurality of conveyor belts, each conveyor belt being independently power-driven so that the successive teeth 27.2 can move independently of each other. Such a configuration is disclosed in Italian Patent No. 102015000084892.

[0111] Once the group G of products R inserted into the space S is moved forward by the conveyor 27 along the wrapping direction fA, it passes through a folding device 28 which includes a top-side folding device Pls, a bottom-side folding device Pli, a front-side folding device Pla and a rear-side folding device Plp, which respectively form a top-side crease Pls', a bottom-side crease Pli', a front-side crease Pla' and a rear-side crease Plp', as Figures 9D - 9G successively shown. The top-side folding device Pls, the bottom-side folding device Pli and the front-side folding device Pla are generally fixed, while the rear-side folding device is movable along a double arrow Fplp. The movement of the rear-side folding device can be coordinated with the movement of the movable bottom folding devices 25, 26 so as to simultaneously produce their respective creases, or to produce the rear-side crease Plp' immediately after the two edges B1, B2 are overlapped. In addition, a single power drive can be used to move the movable bottom folding devices 25, 26 and the rear-side folding device Plp. In some cases, the rear-side folding device Plp can effect the corresponding folding before the group G of products R is moved by the conveyor 27. In other cases, the rear-side folding device Plp can effect the folding when the group G of products R has been moved by the conveyor 27.

[0112] Thus, the group G of product R moves forward along the direction fA through the folding device 28, allowing the folding side edges L1, L2 to form the side creases Pla’, Plp’, Pli’ and Pls’ of the paper wrapping sheet F on the front and back surfaces of the group G of product R, as Figures 9A - 9G shown. For example, this type of side folding member can also be implemented as described in EP1228966.

[0113] Below, with reference to Figure 7A and Figure 7B , the sheet supply station 31 for supplying the paper wrapping sheet F will be described, and this sheet supply station 31 supplies one sheet to the wrapping station 19 in sequence each time.

[0114] The sheet supply station 31 includes an unwinding device 38 to unwind the reel B of the paper web material N made of virgin fiber, recycled fiber or a mixture thereof. Preferably, the grammage of the paper web material N is between 10 g / m 2 and 100 g / m 2 , the thickness is between 10 μm and 500 μm, and more preferably between 20 μm and 100 μm. The unwinding device 38 may include a support device for holding the reel B to rotate around its longitudinal axis, and an actuating device for controlling the rotation of the reel B, for example by means of a conveyor belt in contact with the outer surface of the reel B or by connecting the axis of the reel B to a power drive system. The unwinding device can be of any known type, such as that shown in IT1274081.

[0115] The paper web material N can be conveyed by the idler rollers 32.1, 32.2, 32.3, 32.5, 32.5 and 32.6 along the supply path P in the supply direction fN to the cutting unit 37, which is arranged to cut the paper web material N into paper wrapping sheets F of a predetermined length. Along the supply path P of the paper web material N, a dispensing device 133 is provided upstream of the cutting unit 37, and this dispensing device 133 is arranged to apply a sealant S (such as glue) to the paper web material N. The sealant S can preferably be a heat-reactivatable glue, that is, it can have the following characteristics: it does not remain sticky once applied and is only activated during heat treatment. The advantage of this type of sealant is that even in the case of accidental contact between the sealant and the components of the packaging machine 1, it will not dirty the downstream devices (such as the wrapping station 19). Other types of glue can also be used, such as heat-activated glue or glue that is immediately activated and will not be reactivated once dried.

[0116] As described above, the grammage of the paper web material N can be between 10 g / m 2 and 100 g / m 2Between, the thickness can be between 10 μm and 500 μm, and preferably between 20 μm and 100 μm. It has been found that a significant reduction in the amount of sealant applied to the paper web material N (or to the individual cut sheets) is particularly advantageous. Specifically, it has been found that the amount of sealant S provided on each individual sheet (i.e., applied to the individual cut wrapper sheets, or applied to the web material N, a portion of which is cut to form individual wrapper sheets) is suitably less than 30% of the weight of a single sheet (e.g., between 30% and 1% of the weight of the individual sheets; in other words, assuming the weight of the sheet is 100, the weight of the sealant is between 30 and 1), more preferably less than 10% of the weight of a single sheet (e.g., between 10% and 1% of the weight of the individual sheets), and even more preferably less than 5% of the weight of a single sheet (e.g., between 5% and 1% of the weight of the individual sheets). The reduction in the amount of sealant also results in a very small sealant thickness (for the same application area), thus allowing, for example, the acceleration of the step of cooling the adhesive, which must be suitably cooled when it reaches the subsequent processing stations to avoid soiling them.

[0117] The dispensing device 33 may include one or more dispensers 33.1, 33.2, 33.3 disposed above the supply path P so as to apply the sealant S to the web material N in a controlled manner. Preferably, the dispensers 33.1, 33.2, 33.3 may be of the coating type, although other types of dispensers, such as spray dispensers, are not excluded. During the sealant application step, the dispensers (such as those of the coating type) are preferably in contact with the web material N and preferably press on the web material N. Of course, other types of dispensers (such as spray dispensers) may be spaced apart from the web material. The supply path P may preferably be flat in the portion where the sealant is applied. As shown, the dispensers 33.1, 33.2, 33.3 may be supported by a support structure 34 which consists of L-shaped brackets 39 constrained to a crossbar 39A, the ends of the crossbar being attached to two uprights 40. The support structure 34 may be of any other suitable type. The support structure 34 may include means (not shown) for adjusting the lateral position of the dispensers 33.1, 33.2, 33.3 relative to the supply direction fN of the web material N. For example, the L-shaped brackets 39 may slide along linear guides and be locked thereon by screws or other suitable systems. In another configuration (also not shown for simplicity), the L-shaped brackets 39 or generally the dispensers 33.1, 33.2, 33.3 may be adjusted by motors in order to simplify product changeover, i.e., the changeover to packages requiring paper wrapper sheets F of different sizes. Additionally, the dispensing device 33 may be adjusted in height manually or automatically relative to the supply path P. The dispensers 33.1, 33.2, 33.3 may be connected to an electronic control unit 45 (such as a PC or PLC) which manages the application step (i.e., the moments when the dispensers should apply the sealant S to the web material N and when they should not dispense the sealant).

[0118] Upstream of the dispensers 33.1, 33.2, 33.3 along the supply direction fN, the dispensing device 33 may include a phase detection system 36 for coordinating the application of the sealant S with the supply of the web material N. In practice, the web material N may include printed patterns, letters, barcodes, and markings for phase detection which may be visible or invisible on the outside of the package C. In the case where the printed pattern or marking is visible on the outside of the package, its position relative to the package surface must be precise and predetermined. Thus, in such a case, the sealant S must be applied in a manner synchronized with the supply of the web material N and thus with the individual paper wrapper sheets F. In Figures 7A - 7BIn the example, the coordination detection system 36 is implemented by an encoder 43, which can measure the amount by which the web material N moves forward along the supply direction fN. Alternatively, the encoder 43 can detect the position of the web material N to determine the position of a specific printed pattern design. Instead of the encoder 43, other systems or sensors can be used, such as a photocell that detects a given point on the web material N, or a vision system that detects and identifies the position of the web material N. In addition, combinations of these sensors can be used, such as a photocell and an encoder, a photocell and a vision system, etc. The coordination detection system 36 is also connected to an electronic control unit 45 to adjust the application of the sealant S to be coordinated with the forward movement of the web material N.

[0119] Downstream of the dispensing device 33, there is a cutting unit 37 (not shown in detail) to cut the web material N into wrapper sheets F of a predetermined length. The cutting unit 37 can be of the type described in EP1052209B1. The cutting unit 37 is preferably connected to and controlled by the electronic control unit 45 to perform the cutting of the web material N in coordination with the printed pattern (if any) and with the sealant S applied to the web material N. The cutting should also be coordinated with the web material N to form the paper wrapper sheets F of the desired length. Preferably, the cutting is of the "scissors" type and is performed by a rotating blade working in cooperation with a fixed mating blade, and the two blades are at least as wide as the web to be cut. Once cut and leaving the cutting unit 37, the paper wrapper sheets F are fed along the sheet supply direction fF, which is generally parallel to the supply direction fN of the web N, but when using a cutting unit with a different than preferred configuration (as shown in EP1052209B1), the sheet supply direction can also be different from the supply direction of the web (e.g., orthogonal).

[0120] In different configurations (not specifically shown in the figures), the cutting unit 37 can be provided upstream of the dispensing device 33, in which case it must be directly coordinated with the paper wrapper sheets F. Obviously, in this case, a coordination detection device 36 is also provided, and its operation is similar to the above operation. In this configuration, the dispensing of the sealant S and the supply of the paper wrapper sheets F can also be coordinated by a photocell that detects the lateral edge of the paper sheet moving forward along the sheet supply direction fF.

[0121] Generally speaking, in order to obtain sheets of the desired size, coordinated with any printed pattern and with the sealant S, it is necessary to alternately:

[0122] ο Coordinate the application of the sealant S with the web material N, and then coordinate the web material N with the cutting unit 37;

[0123] Coordinate the cutting unit 37 with the web material N, and then coordinate the paper wrapping sheet F with the dispensing device 33.

[0124] As Figure 10 shown in and FIG. 11, the application of the sealant S on the web material N can be performed in more than one configuration. For example, in Figure 10 , a paper wrapping sheet F defined by two parallel side edges and two side edges transverse to the supply direction fN is shown. The dispensing device 33 has applied a sealant line SCP to the paper wrapping sheet F along the side edge parallel to the supply direction fN, and sealant lines SCT along the two side edges transverse to the supply direction fN. The sealant lines SCP and SCT can be continuous or discontinuous, such as dotted lines. In Figure 10 's case, the line SCP is continuous, while the two lines SCT are respectively formed by alternating two sections SM1, SM2 with sealant and two sections ZL1 (possibly ZL2) without sealant. Preferably, the section ZL1 without sealant S between the two sections SM1, SM2 of the sealant S included in the same line SCT respectively corresponds to the parts of the sheet that will form the top side edge crease Pls' and the bottom side edge crease Pli' (so that there is no glue on the outer surface of the package). In Figures 9A - 9G 's complete wrapping sequence case, the line SCT is continuous (the glue (if any) on the outer surface of the package may not be activated or dried). Generally, the line SCT is applied so that there are sections of the sealant S between the front side edge crease Pla', the rear side edge crease Plp', the bottom side edge crease Pli' and the top side edge crease Pls', and its activation by means of the sealing station 40 will permanently stabilize the package C of the product R. The line SCP is applied to the paper wrapping sheet F so as to be located between the overlapping edges B1, B2, so that the sealant S can be heated by the transverse sealing device 30 and thus activated. As Figures 9A - 9G shown, the line SCT on each side of the package C can form an "H" - shaped seal. The horizontal section of the "H" shape is formed by the line SCT applied to the parts of the paper wrapping sheet F that constitute the top side edge crease Pls' and the bottom side edge crease Pli', if they are arranged to overlap each other. The vertical sections of the "H" shape are formed by the parts of the line SCT corresponding to the parts of the paper wrapping sheet F that form the front side edge crease Pla' and the rear side edge crease Plp'. If the line SCT is not arranged to completely overlap each other, the seal is rectangular, where the lower side is determined by the line SCT applied to the side of the paper wrapping sheet F that forms the top side edge crease Pls', the upper side is determined by the line SCT applied to the side of the paper wrapping sheet F that forms the bottom side edge crease Pli', and the two vertical sides are determined as in the previous case.

[0125] The lines SCP and SCT are typically applied generally parallel to the edge sides of the wrapping sheet F, although this is not strictly necessary. The width of the lines SCP and SCT can be between 5 mm and 80 cm. The width of the lines can also be adjusted based on the desired dimensions of the package C. The lines SCP and SCT can be applied at a distance between 0.5 mm and 50 mm, preferably between 1 mm and 25 mm, from the edge of the side of the paper wrapping sheet F.

[0126] The dispensers 33.1, 33.2, 33.3 can be configured to have different distributions of the sealant S. For example, instead of continuous or discontinuous sections of the line SCT, dotted sections or other shapes (such as triangles) can be applied, which, once the flaps L1 and L2 are folded, coincide with the overlapping area of the side creases, as Figure 11A and Figure 11B schematically shown in. Also, in this case, the purpose of applying the sealant S is to obtain a stably sealed package C for most of the area enclosed by the sealant S. In a preferred embodiment, the distribution of the sealant S is such that the package C is completely stably closed, preventing the product R from being contaminated or at least preventing its contact with external substances. The package C can have a convenient opening system or handle for facilitating the transportation of the package C, however, without changing the purpose and embodiments of the present invention. Examples of handles are described in EP1535846, while a convenient opening system is disclosed in EP2225159.

[0127] Figure 8A An example of the supply station 31 is shown, which is Figure 7A and Figure 7B a variant of the supply station shown in.

[0128] The reel B is unwound, and the web material N is conveyed by one or more rollers along the supply path P in the supply direction fN to the cutting unit 37, which is arranged to cut the web material N into paper wrapping sheets of a predetermined length. Along the supply path P of the web material N, a dispensing device 133 is provided upstream of the cutting unit 37, which is arranged to apply the sealant S (such as glue) to the web material N. As described above, the sealant S can be a heat-reactivatable adhesive. The path P is longer than Figure 7A and Figure 7B the paths, and includes, for example, a series of sections leaving the dispensing device 133, namely, a section P1 from bottom to top, a section P2 that is almost horizontal, a section P3 from top to bottom, a section P4 returning towards the dispensing device 133, and a final section P5 entering the cutting unit 37. The dispensing device 133 acts on the web material N along the section P1 from bottom to top.

[0129] The dispensing device 133 has at least three sealant dispensers, preferably arranged along a line orthogonal to the supply direction of the web material N. The dispensers are divided into at least two dispensing units, where at least one dispensing unit consists of a plurality of dispensers. Preferably, at least three dispensing units are provided, namely, a first dispensing unit 133.1, a second dispensing unit 133.2, and a third dispensing unit 133.3. The first dispensing unit includes a plurality of first dispensers 133.1', the second dispensing unit includes a plurality of second dispensers 133.2', and the third dispensing unit 133.3 includes a single dispenser 133.3'.

[0130] All the dispensers of the dispensing units are arranged on a crossbar 139A, which is orthogonal to the supply direction of the web material N and is arranged in a straight line. The dispensers of each dispensing unit are adjacent to each other along the crossbar 139A. The dispensing units can be spaced apart along the crossbar (so that the last dispenser of one dispensing unit is not adjacent to the first dispenser of the next dispensing unit). The position of the dispensers can be adjusted manually or by an automatic actuation system (schematically indicated by the arrow R1) along the crossbar 139A. The dispensers are preferably of the contact type for pressing the web material N so that the sealant can be applied. Thus, a system can be provided to move the crossbar towards / away from the web material N (schematically indicated by the arrow R2) (manually or automatically).

[0131] Each dispenser 133.1', 133.2', and 133.3' is operatively connected to a supply system W for supplying the sealant S, which supply system includes a plurality of conduits W1 (only some of which are schematically shown for simplicity in Figure 8A ), such that each dispenser has a respective conduit for supplying the sealant in a molten state, for example, from a tank W2, where the sealant is stored in the tank W2 in a molten state (e.g., due to the presence of an electric melter for melting solid sealant particles). Each dispenser is associated with a valve W3 (only a few of which are schematically shown for simplicity in Figure 8A ), which valve is, for example, an electromagnetic valve that allows the dispenser to supply / not supply, i.e., to apply the sealant to the web material or not to apply it to the web material.

[0132] The sealant supply system includes pumping equipment W4 operatively connected to the conduits W1, such as a supply pump. Appropriately, the supply pump can be of a type having a variable flow rate depending on the supply speed of the web material or depending on the production speed of the packaging machine, so as to control the amount of sealant applied to the web material N and ensure a sufficient flow rate of the sealant in order to apply an amount of sealant suitable for a specific purpose (e.g., the higher the increase in the production rate of the packaging machine measured in packages per minute, the greater the number of sheets to which the sealant needs to be applied per minute, which situation requires an increase in the flow rate of the sealant S to the dispensers). Everything is controlled by a control unit.

[0133] In this example, the sealant distribution is the same as Figure 10 . The first dispensing unit 133.1 and the second dispensing unit 133.2 apply the line SCT (i.e., the line orthogonal to the supply direction fN), while the third dispensing unit 133.3 applies the line SCP (i.e., the line parallel to the supply direction fN). More specifically, the first dispensing unit 133.1 applies the second segment SM2 of each line SCT, while the second control unit 133.2 applies the first segment SM1 of each line SCT. The distance between the first dispensing unit and the second dispensing unit substantially corresponds to the distance ZL1 between the segment SM1 and the segment SM2. Similarly, the distance between the second dispensing unit 133.2 and the third dispensing unit 133.3 substantially corresponds to the distance between the segment SM1 of the line SCT and the line SCP. In practice, each of the segments SM1 and SM2 is formed by several regions adjacent to each other along the line (each region is in contact with or very close to the adjacent region, e.g., the distance is less than 10 mm). For example, the first region Sx’ of the segment SM2 is applied by the first dispenser 133.1’ which applies the sealant in a first direction consistent with the sheet / web material supply direction fN, and the second region Sx” adjacent to the first region Sx’ is applied by the second dispenser 133.1’ which is adjacent to the first dispenser and applies the sealant in the same first direction; the second dispenser is adjacent to the first dispenser according to the second extension direction of the crossbar 139A which is orthogonal to the sheet / web material supply direction. This is the case for all dispensers of the first dispensing unit 133.1. The same applies to the segment SM1 of the line SCT which is achieved by the sealant regions adjacent to each other in series applied by the dispenser 133.2’.

[0134] In practice, the width of each region (e.g., measured along the direction orthogonal to the supply direction fN, i.e., parallel to the extension of the crossbar 139A) is equal to the operating width of the dispenser (i.e., e.g., approximately corresponding to the width of the nozzle / aperture of the dispenser), and the height (orthogonal to the width) is the result of the actuation time of the dispenser on the moving web material (the corresponding solenoid valve is opened to supply the molten sealant to the corresponding dispenser). Therefore, the line SCT or its segments can be regarded as a set of these regions formed by adjacent dispensers. Obviously, if a higher line SCT (direction fN) is required, it is sufficient to increase the opening time of the solenoid valves of the first dispensing unit and the second dispensing unit.

[0135] The line SCP orthogonal to the line SCT is arranged in a direction parallel to the supply direction fN of the sheet / web material, and its width is equal to the operating width of the dispenser. In this case, the height of the line SCP is greater than the height of the regions of the segments SM1 and SM2 that constitute the line SCT in the above example, because it is provided by actuating the dispenser (i.e., opening the corresponding solenoid valve) on the moving web material for a longer time than in the previous example (the line SCT). In this case, the line SCP is a continuous line and is not composed of adjacent (contiguous) regions. If a wider line SCP is required, one (or more) additional dispensers can be arranged beside the single dispenser 133.3' of the third dispensing unit 133.3.

[0136] Similarly, by increasing or decreasing the number of dispensers in each dispensing unit, the widths of the segments SM1 and SM2 can be changed. It is also possible to have multiple dispensers to cover the entire width of the sheet / web material, and the dispensers corresponding to the intersection regions where the sealant should not be applied can be deactivated or not enabled, or the corresponding solenoid valves can be kept closed all the time.

[0137] In Figure 8B for example, with reference to a station 31 similar to Figure 7A and 7B a cooling device K is also provided for cooling the sealant S applied to the web material N. The cooling device K is arranged along the path of the web material N downstream of the region where the sealant S is applied and upstream of the cutting unit 37.

[0138] The cooling device K includes, for example, one or more air injection nozzles K1, which are operably connected to an air distribution system schematically represented by K2 and are directed towards the web material N. The total jet or flow rate (in the case of multiple nozzles, the sum of the cross-sectional widths of the jets or flow rates) of the air injection nozzles transversely surrounds the entire web material N or only one or more parts of the web material (e.g., because the sealant S is applied to only one or more parts of the web material N).

[0139] For example, the cooling device K is adapted to form a laminar air flow Q on the web material N. For example, the cooling device K includes a plate having a surface K3 facing a part of the path of the web material N, and this surface defines a laminar air channel together with the web material. For example, the surface K3 can be flat and is generally parallel to the part of the path of the web material N that it faces.

[0140] For example, the sealant cooling device K can be similar to that described in EP1886950. Thus, the surface K3 can be flat and can be substantially parallel to that part of the path of the web material N it faces, and can have an air inlet portion K4 towards which the nozzle K1 points, and this air inlet portion converges towards that part of the path of the web material N and is continuously contiguous with the surface K3.

[0141] The cooling device K can include one or more Coandă effect nozzles K1, such as those described in EP1886950.

[0142] Figure 8C An example is shown in which, as Figure 8B shown, the cooling device K consists of several cooling elements K', for example in order to extend that part of the path of the web material N that is cooled. In this case, each cooling element K' is associated with a corresponding part of the path of the web material N, and preferably each cooling element is associated with a corresponding air injection nozzle K3.

[0143] Once the paper wrapping sheet F applied with the sealant S has been prepared in one of the aforementioned ways, the sheet moves forward along the sheet supply direction fF towards the wrapping station 19. In a preferred embodiment, the paper wrapping sheet F is held at two edges B1 and B2 by a supply member 20 (such as a conveyor belt) and is positioned orthogonally to the lifting direction f16, as described above. Such an embodiment is described, for example, in the patent document WO2021009339.

[0144] In Figures 12 to 15 , a sealing station 40 is shown, which is configured to seal the paper wrapping sheet F wrapped around the group G of products R forming the package C to be sealed. The sealing is achieved by heat-treating the creases of the previously formed paper wrapping sheet F. In practice, once the folding of the side flaps L1 and L2 has been completed, it is necessary to stabilize, for example, the front side flap crease Pla', the rear side flap crease Plp', the bottom side flap crease Pli' and the top side flap crease Pls' obtained according to the Figures 9A - 9G described packaging cycle, and this is obtained by heat-treating the planes F1, F2 of the Figure 9G package C.

[0145] The sealing station 40 includes a supply channel 41 for moving the package C to be sealed forward along the sealing direction fS, and the supply channel 41 is formed by a pair of sealing members 42A, 42B arranged opposite to each other on both sides thereof. The sealing members 42A, 42B may respectively include preferably uniform sealing surfaces 43A, 43B made of ferromagnetic material (or containing paramagnetic material). The sealing surfaces 43A, 43B are the parts of the sealing members that face and thus contact the package C to be sealed. In the case shown in the figure, the sealing members are respectively realized by belts 54A and 54B of ferromagnetic material (or containing paramagnetic material). In a variant of the present invention (not shown), each sealing member 42A, 42B may use two or more steel belts arranged vertically adjacent to each other. The total height of the steel belts of each sealing member 42A, 42B is at least equal to the height of the package C to be sealed.

[0146] Each of the sealing members 42A, 42B can be driven between return members 44A, 45A, 46A and 44B, 45B, 46B (such as pulleys or rollers), and for each sealing member, at least one of the return members is preferably power-driven. In this particular case, the return members 44A and 44B are driven by corresponding actuating devices M1 and M2 (such as gear motors) for supplying the package C to be sealed along the sealing direction fS. In different configurations, the sealing members 42A, 42B can be made idle, that is, without an actuating device, especially when the supply channel 41 includes a power-driven conveyor 47 for supplying the package C to be sealed along the sealing direction fS. In a preferred embodiment of the present invention, both the sealing members 42A, 42B and the conveyor 47 are power-driven. When the conveyor 47 is not power-driven, it can be replaced by a simple supply plane (such as an extension of the sliding surface 23). The conveyor 47 can be arranged at the package height Qa so as to receive the package C to be sealed without moving vertically relative to the sliding surface 23, and such a movement would move the crease to be sealed, thereby impairing the final quality of the package.

[0147] The sealing members 42A, 42B can be arranged close to the outlet of the packing station 19 (i.e., arranged continuously with the outlet of the packing station 19) so as to receive the package C to be sealed while the folding device 28 is still in partial contact with the newly formed crease, thereby forming a continuous or almost continuous passage between the folding device 28 and the sealing members 42A, 42B, and preventing the newly formed front side crease Pla’, rear side crease Plp’, bottom side crease Pli’ and top side crease Pls’ from deforming. Preferably, when the sealing members 42A, 42B and / or the conveyor 47 are driven by power, the package C to be sealed is received by feeding the package C to be sealed along the sealing direction fS at a speed equal to or preferably higher than the speed along the packing direction fA, so as to move the package C to be sealed away from the conveyor 27 and prevent the rotation of the teeth 27.2 around the pulley 27.3 from deforming the package C that still needs to be sealed and stabilized.

[0148] The sealing surfaces 43A, 43B of the sealing members 42A, 42B can be heated by induction, radiation or conduction. In the preferred embodiment shown herein, the sealing surfaces 43A, 43B are heated by induction of the electromagnetic induction devices 48A, 48B respectively, which include one or more induction coils 49A, 49B (or other circuits capable of generating a time-varying electromagnetic flux, the electromagnetic flux depending on the induction current passing through it). The induction coils 49A, 49B can be arranged to face the sealing surfaces 43A, 43B, or arranged on the opposite side, i.e., arranged within the region defined by the closed path determined by the sealing members 42A, 42B. For example, the induction coils 49A, 49B can be provided in the straight portions between the corresponding return members 45A, 46A and 45B, 46B. In other configurations, the induction coils 49A, 49B can be provided, for example, between the return members 44A, 46A and 44B, 46B or between the return members 44A, 45A and 44B, 45B. In the latter case, the induction coils 49A, 49B cannot be placed in front of the sealing surfaces 43A, 43B because it will be inside the supply channel 41; but it should be arranged on the opposite side, i.e., within the region defined by the sealing members 42A, 42B.

[0149] The corresponding generators or inverters 50A, 50B are associated with the electromagnetic induction devices 48A, 48B and are controlled to supply an electromagnetic induction current suitable for generating a time-varying electromagnetic flux to the induction coils 49A, 49B. As the sealing members 42A, 42B pass by, eddy currents are generated. The eddy currents heat the sealing members 42A, 42B by the Joule effect.

[0150] The inverters 50A, 50B operate at an operating frequency approximately equal to the resonant frequency of the circuits formed by the respective induction coils 49A, 49B. The operating frequency of the electromagnetic induction current generated by the inverters 50A, 50B is between 10 Hz and 500 kHz, more preferably between 100 Hz and 100 kHz.

[0151] To adjust the operating temperature of the sealing members 43A, 43B, a closed-loop control system can be used, which includes the inverters 50A, 50B and at least one temperature sensor of any type (such as a thermocouple, pyrometer, thermal camera or other suitable device), which is associated with the respective sealing members 42A, 42B and is connected to a control unit that controls the inverters 50A, 50B based on an appropriate control algorithm, thereby adjusting the temperature of the sealing surfaces 43A, 43B. The control unit can be a PC or a PLC 45, or a different control device, such as another PC or PLC or an industrial computer, microprocessor, computer network or any other suitable device.

[0152] The operating temperature of the sealing surfaces 43A, 43B can be between 100 °C and 400 °C, preferably between 150 °C and 300 °C. The operating temperature can vary greatly as it depends on the operating conditions of the packaging machine 1, the production speed, the type of paper wrapping sheet F, and the type and quality of the sealant S.

[0153] In order to increase the production flexibility of the packaging machine 1, the sealing station 40 includes adjusting means for adjusting the lateral distance between the sealing members 42A, 42B, thereby allowing the machine to adapt to the specifications of the package C to be manufactured. The adjusting means for adjusting the lateral distance between the sealing members 42A, 42B may include bases 51A, 51B which are movable laterally (i.e., preferably orthogonally to the sealing direction fS) along guides 52, 53. The bases 51A, 51B are slidably constrained to the guide rails 52, 53 by respective shoes 70, 71. When the packaging machine 1 is operating, the distance between the bases 51A, 51B is locked to hold the sealing members 42A, 42B in the desired position. The distance between the bases 51A, 51B is only unlocked when it is necessary to adjust the lateral position of the sealing members 42A, 42B, thereby widening or narrowing the supply channel 41. To adjust the distance between the sealing members, an actuator 73 (in this case a handwheel) is provided which rotates a worm 72 engaging nuts 74, 75 which are integral with the bases 51A, 51B respectively. The worm 72 preferably consists of two parts 72' and 72" having opposite thread directions, such that rotation of the worm 72 causes the bases 51A, 51B (and the corresponding sealing members 42A, 42B) to move towards and away from each other. The actuator 73 may also be an electric motor in order to automatically adjust the cross-sectional dimensions of the supply channel 41.

[0154] In order to achieve an optimal seal, a member 76 may be provided to adjust the sealing pressure, i.e., to apply a predetermined lateral sealing pressure to the package C as it moves along the supply channel 41. As Figure 15 better shown in, the sealing pressure adjusting member 76 is attached to each of the sealing members 42A, 42B and may include a sliding guide 77 integral with the bases 51A, 51B. The sliding guide 77 may be substantially parallel to the guide rails 52, 53. A slider 78 integral with the plate 80 on which the sealing members 42A, 42B are mounted is associated with the sliding guide 77. The bases 51A, 51B are connected to actuators 82, 83 respectively, which are preferably pneumatic or electric actuators, or any other type of actuator suitable for pushing the sealing members 42A, 42B towards each other. If the actuators are pneumatic, the sealing pressure may be adjusted by changing the air pressure, while if the actuators are electric or electromechanical, the control unit 45 or another dedicated control device may move the actuators by moving each of the bases 51A, 51B (and thus the sealing members 42A, 42B) towards or away from each other.

[0155] A tensioning device 60 may be provided for each of the sealing members 42A, 42B to tension the sealing members. In the case where each of the sealing members 42A, 42B consists of two or more bands made of ferromagnetic material (or containing paramagnetic material), a tensioning device 60 is provided for each band. The tensioning device 60 may be implemented by an idler roller 61 that is pressed against the corresponding sealing member 42A, 42B by a pneumatic actuator 62. Other types of actuators may also be used, such as an electric linear motor or other equivalent electromechanical device. If a pneumatic actuator is used, the tension of the corresponding sealing member 42A, 42B can be adjusted by adjusting the air pressure of each pneumatic actuator.

[0156] Preferably, in order to keep the distance between the sealing members 42A, 42B and the corresponding induction coils 49A, 49B constant, the tensioning device 60 may act on the corresponding sealing members 42A, 42B in a portion defined by two consecutive return members 45A, 46A and 45B, 46B and not including the corresponding induction coils 49A, 49B. For example, as shown in the figure, the tensioning device 60 acts on the portion between the return members 44A, 46A and 44B, 46B, while the induction coils 49A, 49B are placed in the portion between the return members 45A, 46A and 45B, 46B. In this way, the deformation caused by the tensioning device 60 on the sealing members 42A, 42B does not affect the portions of the sealing members 42A, 42B facing the induction coils 49A, 49B.

[0157] To achieve optimal sealing, some lateral pressure may be applied to the package C to be sealed as the package C moves along the supply channel 41. This can be achieved by supporting each base 51A, 51B on a slider along a lateral guide rail that is substantially orthogonal to the sealing direction fS and connecting each base 51A, 51B to a pneumatic or electric actuator or any other suitable actuator adapted to push the sealing members 42A, 42B towards each other. If the actuator is pneumatic, the sealing pressure can be adjusted by changing the pneumatic pressure, while if the actuator is electric or electromechanical, the PLC or PC 54 or another dedicated control device moves the actuator by moving each base 51A, 51B (and thus the sealing members 42A, 42B) towards or away from each other.

[0158] The fact of having uniform sealing surfaces 43A, 43B made of ferromagnetic material, such as steel, leads to better heat conduction and heat transfer from the member having the sealing surfaces 43A, 43B to the paper wrapping sheet F. If a compression (albeit very small) is applied to the package C to be sealed as it moves forward in the supply channel 41, a stretching effect is produced at the fold of the paper wrapping sheet F, increasing its aesthetic quality and facilitating the stabilization of the fold. In this way, the packaging can be improved both when it is sealed with a sealant S and when the paper wrapping sheet is free of sealant, because the stretching effect stabilizes the fold of the folds L1, L2 regardless of whether the sealant S is used or not. Finally, a material having a stiffness and hardness similar to steel in addition to being ferromagnetic allows a significantly higher durability than the prior art systems mentioned in the introduction.

[0159] In another embodiment (not shown), sealing members 42A, 42B are formed by flexible members (such as conveyor belts or chains), and sealing surfaces are constrained on the flexible members. The sealing surface can be realized by plates made of steel or other ferromagnetic materials (or containing paramagnetic materials) adjacent to each other. The flexible member can be driven around return members 44A, 45A, 46A and 44B, 45B, 46B, which is completely similar to the above-mentioned steel belt. In this case, the induction coil faces the sealing surface formed by the plate again, and eddy currents are induced on the sealing surface, as described above for the steel belt. In this case, the flexible member bearing the sealing surface can also be made of non-ferromagnetic materials (such as plastics or rubber), because the heated surface suitable for sealing package C is the heated surface of the plate, rather than the heated surface of the flexible member. In this technical solution, a tensioning device 60 very similar to the above can be provided to tension each sealing member 42A, 42B.

[0160] Finally, optionally, contrast means (contrast means, abutment) 90 can be provided to balance any bending when sealing member 42A, 42B contacts with packaging C to be sealed, especially when sealing member 42A, 42B is formed by band 54A and 54B made of ferromagnetic material or containing paramagnetic material.Contrast means 90 is placed on the opposite side relative to sealing surface 43A, 43B, and can include sliding means, band 54A and 54B slides on this sliding means.Sliding means is preferably coated with polytetrafluoroethylene or is made of polytetrafluoroethylene completely, to reduce the friction with band.Sliding means can be equipped with elastic element (such as spring), to allow to move in the direction orthogonal to the sealing direction fS.

[0161] It should be understood that the content shown is merely representative of possible non-limiting embodiments of the present invention, and these embodiments may vary in form and arrangement without departing from the scope of the concept on which the present invention is based. Any reference numerals in the appended claims are merely for ease of reading in accordance with the above description and the drawings, and do not limit the scope of protection in any way.

Claims

1. A packaging machine for wrapping a product group with a paper wrapping sheet, the products being such as toilet paper rolls, kitchen paper towels, napkins and interleaved folded products, the packaging machine comprising: o A supply station for continuously supplying the product group including at least one product one by one; o A wrapping station for wrapping the paper wrapping sheet around the product group; o Sealing means for sealing the paper wrapping sheet around the product group; and o A wrapping sheet supply station for supplying the paper wrapping sheets one by one towards the wrapping station along the sheet supply direction; Wherein the wrapping sheet supply station includes dispensing means for applying a sealant to the paper wrapping sheet.

2. The packaging machine according to claim 1, wherein, The wrapping sheet supply station is arranged upstream of the wrapping station along the sheet supply direction.

3. The packaging machine according to one or more of the preceding claims, wherein the sheet supply station includes: o A cutting unit for cutting out individual paper wrapping sheets from a web material unwound from a reel; o An unwinding device for unwinding the reel of the web material.

4. The packaging machine according to claim 3, wherein the dispensing means is arranged upstream or downstream of the cutting unit along the sheet supply direction.

5. The wrapping machine according to claim 4, wherein the dispensing device is arranged upstream of the cutting unit, and the paper wrapping sheet is delimited by two parallel side edges and two side edges transverse to the sheet supply direction towards the wrapping station, and wherein the dispensing device comprises: At least one dispenser configured to apply a sealant line to an area of the web material corresponding to the paper wrapping sheet in a direction parallel to one of the two side edges parallel to the sheet supply direction, and at least one dispenser for applying a sealant line in a direction parallel to each of the two side edges transverse to the sheet supply direction.

6. The wrapping machine according to claim 4, wherein the dispensing device is arranged downstream of the cutting unit, and the paper wrapping sheet is delimited by two parallel side edges and two side edges transverse to the sheet supply direction towards the wrapping station, and wherein the dispensing device comprises: At least one dispenser configured to apply a sealant line to an individual paper wrapping sheet in a direction parallel to one of the two side edges parallel to the sheet supply direction, and at least one dispenser for applying a sealant line in a direction parallel to each of the two side edges transverse to the sheet supply direction.

7. The packaging machine according to claim 5 or 6, wherein the line is continuous or discontinuous and has a length equal to or less than the length of the corresponding side edge of the paper wrapping sheet.

8. The packaging machine according to claim 5, 6 or 7, wherein the distance between the line and the corresponding side edge is between 0.5 mm and 50 mm, preferably between 1 mm and 25 mm.

9. The packaging machine according to one or more of the preceding claims, wherein the at least one dispenser is of the coating type; preferably of a type suitable for dispensing by contacting the surface to which the sealant is to be applied.

10. The packaging machine according to one or more of the preceding claims, wherein the dispensing means includes adjustment means for adjusting the distance between the at least one dispenser and the paper wrapping sheet, and adjustment means for adjusting the at least one dispenser transversely with respect to the wrapping sheet supply direction.

11. The wrapping machine according to one or more of the preceding claims, wherein the wrapper sheet supply station comprises a detection device for detecting the position of the paper wrapper sheet along the sheet supply direction, and the detection device for detecting the position of the paper wrapper sheet is preferably an encoder.

12. The wrapping machine according to claim 11, wherein the at least one dispenser applies the sealant in a coordinated manner with respect to the position of the paper wrapper sheet.

13. The wrapping machine according to one or more of the preceding claims, wherein the dispensing device comprises at least three dispensers; preferably, the dispensing device comprises at least three dispensing units, wherein at least two of the dispensing units comprise a plurality of dispensers; preferably, the dispensers are aligned along a line orthogonal to the web material supply direction, and the dispensers are preferably capable of translating orthogonally to the supply; preferably, the dispensing device is associated with a sealant supply system; preferably, for each dispenser, the supply system comprises a valve that allows supply / non - supply to the corresponding dispenser; preferably, the first dispensing unit and the second dispensing unit each comprise a plurality of dispensers adjacent to each other along a line, the first unit being spaced apart from the second unit, and the first unit and the second unit are adapted to dispense sealant in a first time interval, thereby creating two spaced - apart sections of a first sealant line, where each section is formed by adjacent sealant regions, and wherein the third dispensing group comprises at least one dispenser that is adapted to dispense sealant in a second time interval longer than the first time interval, thereby creating a continuous sealant line orthogonal to the first line; preferably, the sealant supply system comprises pumping means for supplying sealant to at least one dispenser, and the supply rate of the sealant varies depending on the supply speed of the web material onto which the sealant is to be applied.

14. The wrapping machine according to one or more of the preceding claims, wherein the dispensing device is associated with a sealant supply system, the supply system comprising pumping means for supplying the sealant to at least one dispenser, and the supply rate of the sealant can vary depending on the supply speed of the web material onto which the sealant is to be applied and / or depending on the production speed of the wrapping machine.

15. The wrapping machine according to one or more of the preceding claims, wherein the paper wrapping sheet preferably has a grammage between 10 g / m 2 and 100 g / m 2 and a thickness between 10 μm and 500 μm.

16. The wrapping machine according to one or more of the preceding claims, wherein the dispensing device is adapted to dispense the sealant in such a way that the amount of sealant on each paper wrapper sheet is between 30% and 1% of the weight of the sheet, more preferably between 10% and 1% of the weight of the sheet, and even more preferably between 5% and 1% of the weight of the sheet.

17. A wrapping machine according to one or more of the preceding claims, wherein the supply station for supplying product groups includes a lift for lifting the product groups towards the wrapping station, during the upward movement towards the wrapping station, the product groups contact a paper wrapping sheet arranged parallel to a plane transverse to the lifting direction of the product groups, and when the lift raises the product groups to the horizontal plane of the wrapping station, the paper wrapping sheet forms a partially wrapped shape in an inverted U shape around the product groups.

18. A wrapping machine according to one or more of the preceding claims, wherein the wrapping station includes: o A bottom folding device for completing the partial wrapping of the paper wrapping sheet around the product groups, forming a tubular structure open at opposite sides of the product groups, the open tubular structure having flanges of the paper wrapping sheet to be folded, the flanges extending from each of the two side edges of the product groups; o A front side edge folding device for each of the two side edges of the product groups to fold a part of the flange of the paper wrapping sheet against each side edge, thereby forming a front crease; o A rear side edge folding device for each of the two side edges of the product groups to fold a part of the flange of the paper wrapping sheet against each side edge, thereby forming a rear crease; o A top side edge folding device for each of the two side edges of the product groups to fold a part of the flange of the paper wrapping sheet against each side edge, thereby forming a top crease; o A bottom side edge folding device for each of the two side edges of the product groups to fold a part of the flange of the paper wrapping sheet against each side edge, thereby forming a bottom crease.

19. A wrapping machine according to one or more of the preceding claims, wherein the sealing station includes a supply channel and a pair of sealing members arranged opposite to each other on both sides of the supply channel, each sealing member having a uniform sealing surface made of a ferromagnetic material or containing a paramagnetic material, each sealing member is driven between at least two return members, and the sealing members are respectively associated with electromagnetic sensors.

20. A wrapping machine according to claim 18, wherein at least one member and preferably both members of the pair of sealing members are uniform flexible members made of a ferromagnetic material or containing a paramagnetic material.

21. A wrapping machine according to one or more of the preceding claims, including a cooling device for cooling the sealant applied to the paper wrapping sheet; the cooling device is preferably air-cooled and includes at least one air jet nozzle directed towards the area occupied by at least one paper wrapping sheet.

22. The wrapping machine according to claims 3 and 20, wherein the cooling device comprises at least one air jet nozzle that is directed towards a portion of the web material path that is downstream of the area where the sealant is applied and upstream of the cutting unit, preferably towards the surface of the paper web material that is provided with the sealant; preferably, the cooling device is adapted to form a laminar air flow on the paper web material; preferably, the cooling device comprises at least one surface that faces at least one portion of the web material path and that, together with the web material, defines a channel for the air flow from at least one nozzle; preferably, the nozzle is a Coandă effect nozzle.

23. A method for wrapping a group of sheet-packaged products with paper, the products being, for example, rolls of toilet paper, kitchen paper towels, napkins, handkerchiefs and interleaved folded products, the method comprising the following steps: o successively feeding, one by one, the group of products formed by at least one product; o successively forming and feeding, one by one, the paper wrapping sheets along the sheet feeding direction towards the wrapping station; o wrapping the paper wrapping sheets around the group of products; o sealing the paper wrapping sheets around the group of products, wherein, in the step of forming and feeding the paper wrapping sheets, a sealant is applied to the paper wrapping sheets.

24. The method according to claim 23, wherein the wrapping sheets with sealant are prepared by means of a sealant dispenser.

25. The method according to one or more of the preceding claims, wherein the paper wrapping sheets are defined by two parallel side edges and two transverse side edges with respect to the sheet feeding direction, and wherein the step of preparing the paper wrapping sheets with sealant provides for the dispensing of sealant lines along a direction parallel to one of the two side edges parallel to the sheet feeding direction, and along a direction parallel to each of the two transverse side edges with respect to the sheet feeding direction.

26. The method according to claim 25, wherein the lines are continuous or discontinuous and have a length equal to or less than the length of the corresponding side edges of the paper wrapping sheets.

27. The method according to one or more of claims 23 to 26, wherein the lines are applied to the paper wrapping sheets at a distance between 0.5 mm and 50 mm, preferably between 1 mm and 25 mm, from the corresponding side edges.

28. The method according to one or more of the preceding claims, comprising the step of cutting individual paper wrapping sheets from a web material unwound from a reel.

29. The method according to claim 23, wherein the step of forming the paper wrapping sheets comprises the step of unwinding a continuous paper wrapping web and the step of cutting the continuous web into individual paper wrapping sheets.

30. The method according to claim 29, when the step of cutting the wrapper sheet occurs before the step of preparing the paper wrapper sheet with the sealant, the method includes detecting the position of the paper wrapper sheet along the sheet supply direction and the step of applying the sealant in coordination with the position of the wrapper sheet; or when the step of cutting the wrapper sheet occurs after the step of preparing the paper wrapper sheet with the sealant, the method includes detecting the position of the web material and the step of applying the sealant in coordination with the position of the web material.

31. The method according to one or more of the preceding claims, including the step of cooling the sealant provided on the paper wrapper sheet by an air flow after the application of the sealant; if the sealant is applied to the wrapper sheet before the wrapper sheet is cut from the web material, it is preferred to perform the cooling step on the web material before the cutting step, or if the sealant is applied to separate individual sheets, perform the cooling step on each wrapper sheet; preferably, the cooling air flow is generated by the Coanda effect.

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