Patent Publication Number: US-2022219859-A1

Title: Interlocking packaging article and its forming method and apparatus

Description:
INVENTIVE FIELD 
     The present invention is included in the field of packaging articles such as trays or caps obtained from spread out or die-cut sheets, preferably made of cardboard, by folding suitable walls and flaps of said die-cut sheet. 
     BACKGROUND 
     Packaging articles are known in the state of the art, in particular trays or caps with flaps, suitable for different uses, such as for example for containing products packages. 
     In particular, in the following reference will be often made to trays used to contain bottles or other containers and used to facilitate their palletization and storage, without this being limiting for the invention. Reference will also be made to trays used as caps adapted to contain bottles or other containers and used to facilitate their palletization and storage. 
     The aforesaid trays or caps preferably have dimensions similar to those of a pallet or a fraction/portion of the pallet on which the products are to be stored. 
     Said trays or caps are preferably obtained from spread out cardboard sheets, also called die-cut sheets which, after exiting the die-cutting press, are suitably folded manually or by means of machines for forming the trays or caps. 
     In the following, we will talk about the tray, but said term also refers to the tray used as a cap, that is the cap. 
     The die-cut sheet generally comprises a base wall from which walls and flaps extend on which creasing/fold lines are defined to fold them and create the rimmed tray. 
     Tray forming machines generally provide for a warehouse in which the die-cut sheets are stacked and from which they are withdrawn to be placed inside the forming area where a plurality of forming walls are shaped in such a way as to obtain those folds from the spread out sheet defined by the creasing/fold lines previously made during die-cutting. 
     At the end of said operation, which is similar to a deep drawing operation, the flaps which rest on the adjacent walls of the tray are fixed to said walls generally by means of glue or staples in order to maintain the closed shape of a rimmed tray. 
     Said fixing systems by means of glue or staples, have the disadvantage of being expensive systems as they require to equip the machines for forming trays with complex equipment. 
     For example, the forming machines which provide for fixing the tray by gluing include melting devices for preparing the glue, applicators for distributing the glue in the gluing points and relative pipes, generally heated, for conveying the glue from the melter to the applicators. 
     In addition to the complexity and cost of these equipment, the management cost must also be considered and in particular in terms of energy for their operation, but also in terms of maintenance and glue supply. 
     Likewise also the forming machines which provide for fixing the tray by means of staples, require gun devices generally supplied with compressed air for the application of said staples. Also in this case, in addition to the cost of the equipment, its cost of energy management, maintenance, etc. is added. 
     Said fixing system also presents a problem linked to the risk of contaminating the product that is contained and stored in the tray. In fact said staples could fall for example inside said containers. 
     Furthermore, it should be noted that the aforesaid tray closing systems involve difficulties in the recycling of the material, once the cycle of use of the tray is finished, since the glue or the staples must be separated from the cardboard. 
     In the state of the art, tray interlocking systems are also known. 
     These systems are little used today, because they are made with complex interlocks that make it difficult to automate the closure of the tray inside forming machines. 
     Known interlocking systems are also made in such a way that they create overall encumbrances towards the inside of the formed tray. 
     This hinders the correct insertion of the containers in said trays. 
     In fact, once the tray has been formed, the containers, for example bottles or vases, are arranged inside it and placed on the base wall of the tray so as to form a layer of containers retained by the walls of the tray itself. The containers possibly occupy the entire base wall of the tray, making the most of its surface, in order to guarantee optimized storage both in terms of space and stability. 
     The presence of interlocking elements that protrude towards the inside of the tray can prevent the insertion of the container, generating falls of the article itself and instability of the layer. 
     Known interlocking systems also hinder the correct positioning of the cap on the containers. 
     In fact, once the cap is formed, it is placed above a layer of containers such as bottles or jars which are therefore retained in position by the walls of the cap itself. The containers, particularly if wide-mouthed jars, possibly occupy the entire base wall of the cap, making the most of its surface, in order to guarantee optimized storage both in terms of space and stability. The presence of interlocking elements which protrude towards the inside of the cap can prevent the insertion of the cap on the layer of containers, generating falls of the article itself and instability of the layer. 
     On the contrary, trays or caps made using glue or staple fixing systems, have an inner surface without obstructions or obstacles to the insertion of the containers. 
     However, the interlocking fixing system of the tray or cap has the big advantage that for its closure and fixing it does not require forming machines equipped with complex equipment, with high purchase, management and maintenance costs. 
     SUMMARY 
     The technical problem underlying the present invention is that of making available a packaging article which is structurally and functionally designed to overcome one or more of the limits set out above with reference to the known prior art. 
     In the context of the aforesaid problem, a main object of the invention is that of providing a packaging article which allows to keep an internal perimeter free from encumbrances. 
     A further object of the invention is also that of making available to the art a packaging article as part of a simple rational solution which, for manufacturing it, does not require complex equipment, with high purchase, management and maintenance costs. 
     These and other objects are reached by the characteristics of the invention as set forth in the independent claims. The dependent claims outline preferred and/or particularly advantageous aspects of the invention. 
     In particular, the present invention makes available a packaging article in particular made by means of a sheet of foldable material; said article comprising a base wall and sidewalls connected with the edges of said base wall by folding lines, wherein at least two preferably opposite sidewalls comprise an extension flap which protrudes from each end of said sidewalls and is connected thereto by a fold line, whereby the extension flap folds arranging itself in face-to-face relationship with a portion of the adjacent sidewalls. 
     Said packaging article comprises connection means for fixing the extension flap on the portion of the adjacent sidewalls, wherein said connection means comprise a male element and a female element configured in such a way that a portion of the male element, when inserted into the female element, protrudes towards the outside of the formed packaging article. 
     Thanks to this solution, the formed packaging article does not have protruding elements, that is, inside the base wall delimited by the walls, there are no elements that can hinder the insertion of the containers. 
     In fact, the male element of the interlocking means faces towards the outside of the packaging article, that is, towards the outside of the sidewalls. 
     Another aspect of the invention is that of making available a packaging article, in which the flap is fixed to the portion in such a way that the flap rests on the portion, remaining outside the packaging article. Preferably the flap is fixed to the portion so that the inner face of the flap, that is, the one facing the inside of the packaging article, rests on the outer face of the portion, that is, facing towards the outside of the packaging article. 
     Thanks to this solution it is possible to guarantee an easy insertion of the containers into the tray and/or cap formed, since there are no obstacles inside. In fact, the flaps are also external to the perimeter defined by the sidewalls. 
     To avoid having encumbrances inside the packaging article, the female element of the connection means is preferably formed on the extension flap, while the male element is preferably formed in the portion of the sidewalls. 
     A further advantage of the invention is that of enabling the formation of the packaging article without requiring complex and expensive methods or equipment for connecting the flaps to the sidewalls. 
     In fact, the method for manufacturing a packaging article by means of a sheet of foldable material provides for folding the sidewalls along fold lines and folding, the extension flaps which protrude from the ends of said sidewalls, arranging said extension flaps in face-to-face relationship with a portion of the adjacent sidewalls. 
     Said method provides for fixing each extension flap on the portion by exerting a thrust action on the connection means of the packaging article, with a movement directed from the inside towards the outside of the packaging article, and inserting the male element inside the female element so that a portion of said male element protrudes from the female element, towards the outside of the packaging article. 
     Likewise, the apparatus for manufacturing a packaging article, by means of a sheet of foldable material, provides forming means for folding the sidewalls along fold lines and folding, along a fold line, the extension flaps which protrude from the ends of said sidewalls, arranging said extension flaps in face-to-face relationship with a portion of the adjacent sidewalls. 
     Said apparatus provides for fixing each extension flap on the portion by means of thrust devices which act on the connection means of the packaging article, inserting the male element inside the female element, by means of a movement directed from the inside towards the outside of the packaging article so that a portion of said male element protrudes from the female element towards the outside of the packaging article. 
     Said objects and advantages are all achieved by the packaging article and relative method and forming apparatus, object of the present invention, which is characterized by what is provided in the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This and other features will be more apparent from the following description of some of the embodiments, illustrated purely by way of non-limiting example in the accompanying drawings. 
         FIG. 1 : illustrates an axonometric view of a packaging article formed according to the invention; 
         FIG. 2 : illustrates a die-cut spread out sheet for manufacturing a packaging article according to the invention; 
         FIG. 3 : illustrates an axonometric view of a tray formed according to the invention in which the containers are inserted; 
         FIG. 4 : illustrates an axonometric view of a cap formed according to the invention inserted on the containers; 
         FIG. 5 : shows a view from above of a packaging article formed according to the invention; 
         FIG. 6 : illustrates an axonometric view of a packaging article with thrust devices for the forming thereof; 
         FIG. 7 : an axonometric view of the possible steps of forming a packaging article according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With particular reference to  FIG. 1 , a packaging article  100  is shown, in particular a tray  200  and/or cap  300 , in its closed configuration, that is, formed and ready to receive, for example, the containers to be stored. 
     In the following, for simplicity&#39;s sake the talk will be about packaging article  100  to indifferently indicate a tray  200 , or a cap  300 . 
     Said packaging article  100  is made by means of a sheet  400  of foldable material which will be also called spread out die-cut sheet. 
     For example, cardboard sheets are generally widely used as this is a material with adequate resistance characteristics to support layers of containers arranged one above the other, to form a pallet. 
     In addition, cardboard is an easily recyclable and biodegradable material once the cycle of use of the packaging article  100  is finished. 
     An example of cardboard that can be used is corrugated cardboard. 
     Technically, corrugated cardboard is a sandwich consisting of two sheets of flat cardboard and one or more sheets of corrugated cardboard held together by adhesives. If there are two or more corrugated cardboard sheets, another flat cardboard sheet is placed therebetween. Hence, this is called corrugated cardboard with single, double wave etc. Each of the elements that make up a certain type of corrugated cardboard can be different in terms of material, thickness and weight and together with the others it influences the characteristics of the finished product. 
     Said packaging article  100  comprises a base wall  101 , sidewalls  110 ,  120  connected with edges  102  of said base wall  101  by fold lines  103 . 
     Said fold lines  103  or creasing lines are made during the die-cutting step of the spread out sheet  400  and will be used to define the correct positions in which the sheet  400  must be folded to make the closed or formed packaging article  100 . 
     In particular in the sector of palletizing glass bottles or jars, where trays  200  and/or caps  300  are widely used for palletizing said containers, the base wall  101  has a substantially rectangular shape. 
     The pallet is generally composed of the superposition of several trays  200  and/or caps  300 , wherein each tray  200  and/or cap  300  contains a layer of containers/packages. The size of the base wall  101  of the tray  200  and/or cap  300  is substantially similar to that of the pallet located on the base wall of the pallet which for example can be 1000×1200 mm or 800×1200, etc. 
     Alternatively for storage needs, the size of the base wall  101  can also be a portion or fraction of the pallet which is located at the base wall of the pallet. 
     Said base wall  101  preferably has chamfered corners  104 , reducing the presence of sharp edges in such a way as to facilitate the subsequent packaging steps of the pallet, known to a person skilled in the art. 
     In accordance with the aforesaid purposes, the packaging article  100  has two opposite sidewalls  110  and two opposite sidewalls  120 . 
     A preferred embodiment provides that the preferably opposite sidewalls  110  comprise an extension flap  111  which protrudes from one end  112  of said sidewalls  110  and connected thereto by a fold line  113 . 
     By means of said fold line  113 , during the step of forming from spread out sheet  400  to closed packaging article  100 , the extension flap  111  folds, arranging itself in face-to-face relationship with a portion  121  of the adjacent sidewalls  120 . 
     Indifferently, the extension flaps  111  can be included in the sidewalls  120  and in this case they will bend in a face-to-face relationship with a portion of the adjacent sidewalls  110 . 
     The fold line  113 , as shown in  FIG. 2 , can also be more than one in order to optimize the face-to-face superposition of the extension flap  111  with the portion  121 . 
     According to a feature of the invention, the sidewalls  110 ,  120  have a substantially rectangular shape and preferably all have the same height H′. 
     Furthermore, the flap  111  preferably has a height H equal to or smaller than the height H′ of the sidewalls  110 ,  120 . 
     Furthermore, the fold line  113  of the extension flap  111  is preferably substantially orthogonal to the base wall  101  when the packaging article  100  is closed or formed. 
     The flap  111 , as well as the sidewalls  110  and  120 , can have chamfers, recesses, protrusions and dimensions that an expert in the sector is able to define according to the folding and die-cutting needs both to optimize the use of the material that constitutes the sheet  400  and to optimize the forming of the tray  200 . Furthermore, also the folding of the extension flap  111  can take place by means of several fold lines  113 , so as to define a chamfered edge as an alternative to the one of 90° shown in the figures. 
     It is understood however that what is described above has a value of non limiting example, therefore, possible variants of detail that may be necessary for technical reasons and/or functional, are considered from now falling within the same protective scope defined by the claims indicated below. 
     According to an aspect of the invention, said packaging article  100  comprises connection means  130  for fixing the extension flap  111  on the portion  121  of the adjacent sidewalls  120 . 
     The fixing is preferably of the removable type. Said connection means  130  are therefore configured to allow the engagement/disengagement of the extension flap  111  from the portion  121 , unlike the fixing systems with glue or staples whose fixing can be defined as permanent. 
     In a formulation of the present invention, said interlocking means  130  comprise a male element  131  and a female element  132  arranged in such a way that a portion of the male element  131 , when inserted into the female element  132 , protrudes towards the outside of the packaging article  100 . 
     Therefore, towards the inside of the closed packaging article  100 , i.e. inside the base wall  101  delimited by the walls  110 ,  120 , there are no protruding elements that can hinder the insertion of the containers, since the male element  131  of the interlocking means  130  faces towards the outside of the packaging article  100 , that is towards the outside of the sidewalls  120 . 
     In fact, the containers, for example bottles or jars, standing on the base wall  101  of the tray  200 , generally form a layer, possibly occupying the entire base wall  101  of the tray  200  in order to make the most of its surface. This guarantees optimized storage both in terms of space and stability. 
     The presence of connection means  130  which protrude towards the inside of the tray  200  hinders the insertion of the container generating possible falls of the container itself and instability of the layer. 
     Similarly, when the packaging article  100  is used as a cap  300 , this is placed above a layer of containers, for example bottles or jars which are therefore retained in position by the walls of the cap  300  itself. The containers, particularly if wide-mouthed jars, possibly occupy the entire base wall  101  of the cap  200 , making the most of its surface, so as to guarantee optimized storage both in terms of space and stability. The presence of connection means  130  which protrude towards the outside of the cap  300  facilitates its insertion on the container layer, avoiding falls of the containers and instability of the layer. 
     To optimize said result, a possible embodiment of the packaging article  100  provides that the flap  111  is fixed to the portion  121  so that the flap  111  rests on the portion  121 , remaining outside the packaging article  100 . 
     In particular, the flap  111  is fixed to the portion  121  in such a way that the inner face  111   a  of the flap  111 , i.e. facing the inside of the packaging article  100 , rests on the outer face  121   a  of the portion  121 , i.e. facing towards the outside of the packaging article  100 . 
     Thanks to this solution it is possible to guarantee an easy insertion of the containers in the tray  200  and/or cap  300  closed, since there are no obstacles inside the tray  200  and/or cap  300 . In fact, with this solution, the flaps  111  are also external to the perimeter defined by the sidewalls  110 ,  120  as shown in  FIG. 5 . 
     According to a preferred embodiment, the female element  132  of the connection means  130  is formed on the extension flap  111 . 
     Said female element  132  preferably comprises a slit  132   a  carved on the extension flap  111 . 
     Therefore, during the die-cutting of the sheet  400 , in addition to the fold or creasing lines, an incision is also made on the extension flap  111  adapted to define a slit  132   a.    
     Said slit  132   a  remains completely inside the extension flap  111  and therefore does not extend to its edges. 
     According to an aspect of the invention, the female element  132  comprises at least one notch  132   b  on the side of the slit  132   a . Said notch  132   b  preferably has a length shorter than that of the slit  132   a.    
     Said notch  132   b  has the purpose of making the slit  132   a  more deformable in order to facilitate the insertion of the male  131 . 
     Also for this purpose, the female element  132  can comprise, at the ends of the slit  132   a , at least a further cut  132   c , orthogonal to said slit  132   a.    
       FIG. 2  shows a possible configuration of the female  132  in which the notch  132   b  is present on both sides of the slit  132   a.    
     A possible embodiment of the connection means  130  provides that the male element  131  is formed in the portion  121  of the adjacent sidewalls  120 . 
     In particular said male element  131  is shaped like a fin  131   a  carved in the portion  121  of the adjacent sidewalls  120  and connected by a fold line  131   b  to said portion  121 . 
     On a portion of the fold line  131   b  there may be a cut adapted to make the fin  131   a  more flexible. 
     Said fin  131   a  is shown in  FIGS. 1 and 2  with a possible embodiment which provides that said fin  131   a  comprises a first zone  131   c  having substantially the same height A as the fold line  131   b  and a second zone  131   d  which has height B greater than A, moving away from the fold line  131   b . In particular said second zone  131   d  can comprise two teeth  131   e  which preferably project symmetrically with respect to the first zone  131   c.    
     Furthermore, the height A of the first zone  131   c  is smaller than the length A′ of the slit  132   a  in order to guarantee the insertion thereof. Consequently, the second zone  131   d  has height B greater than the length A′ of the slit  132   a.    
     Said second zone  131   d  is configured to pass the slit  132   a  when the packaging article  100  is formed. 
     Therefore the teeth  131   e  are wider than the slit  132   a  itself and once inserted into the slit  132   a  they prevent their removal. 
     As shown in  FIGS. 1 and 3 , the slit  132   a , formed on the extension flap  111 , is preferably substantially parallel to the base wall  101  when the packaging article  100  is closed or formed. Consequently, in order to be able to be inserted into the corresponding slit  132   a , the fins  131   a  are also arranged horizontally. 
     Said embodiment, which provides that the slit  132   a  formed on the extension flap  111 , is arranged substantially parallel to the base wall  101  of the closed packaging article  100 , is particularly advantageous. 
     A first advantage is given by the fact that the slit  132   a  is not constrained by the height H of the extension flap  111 . Therefore also in an extension flap  111  having a low height H (about 40-60 mm), which is fixed to corresponding low sidewalls  120 , it is possible to make the slit  132   a  with the correct size for interlocking the male  131 . 
     Furthermore, said configuration can preferably have two preferred embodiments. 
     The first embodiment is provided, in particular, when the packaging article  100  is used as a tray  200 . 
     In this case the fins  131   a  are arranged horizontally and in such a way that the second zone  131   d  faces towards the base wall  101  of the closed tray  200 . 
     The advantage of this first embodiment is evident when said trays  200  are used to form a pallet made up of the superposition of several trays  200 , in which each tray  200  contains a layer of containers. Generally said pallets provide to be protected by a bag of plastic film which is inserted by special machines. The insertion of said bag, which has dimensions very similar to the pallet, takes place starting from the top of the pallet downwards. 
     The presence of horizontal slits  132   a  and of corresponding fins  131   a  protruding towards the outside from the tray  200  and in such a way that the second zone  131   d , faces towards the base wall  101 , facilitates the insertion of the bag, since this does not create obstacles to the insertion thereof, being positioned in the same insertion direction as said bag. 
     The second embodiment is provided, in particular, when the packaging article  100  is used as a cap  300 . 
     In this case the fins  131   a  are arranged horizontally and in such a way that the second zone  131   d  faces moving away from the base wall  101  of the closed cap  300 . 
     The advantage of this second embodiment is evident when said caps  300  are used to form a pallet made up of the superposition of several caps  300 , wherein each cap  300  contains a layer of containers. Generally also said pallets provide to be protected by a bag of plastic film which is inserted by special machines. The insertion of said bag, which has dimensions very similar to the pallet, takes place starting from the top of the pallet downwards. 
     The presence of horizontal slits  132   a  and of corresponding fins  131   a  protruding towards the outside from the cap  300  and so that the second zone  131   d , faces moving away from the base wall  101 , facilitates the insertion of the bag, since this does not create obstacles to the insertion thereof, being positioned in the same direction of insertion as said bag. 
     Alternative positions of the slit  132   a  such as orthogonal with respect to the base wall  101 , when the packaging article  100  is closed, however, fall within the scope of protection of the invention. 
     Said solution, shown in  FIG. 2 , can be advantageous for example when the height H of the extension flap  111  is high (for example about 100-300 mm) and is fixed to corresponding high sidewalls  120 . Said solution allows to obtain a better tightness of the interlock, and to avoid that the sidewalls  110  and  120  tend to open. 
     Connection means  130  can in fact be made in such a way that they develop in the direction of the height of the sidewalls  120  and/or of the extension flap  111 , so that the connection means  130  are adequate to guarantee a sufficient tightness of the fixing. 
     In fact, it should be considered that the packaging article  100  must maintain its shape even if subjected to any stresses present during the filling phase with containers and during the subsequent handling and storage phases. 
     However, any solution which may include, for example, a slit  132   a  inclined with respect to the base wall  101  of the packaging article  100  formed, or for example solutions which may provide more than one slit  132   a  and also arranged in different ways such as for example two slits  132   a  placed one orthogonal and one horizontal to the base wall  101 , for example formed like a cross, fall within the scope of protection of the invention. 
     The same applies to different conformations of the fins  131   a  which will be shaped from time to time to connect in a removable way in the slits  132   a.    
     In accordance with a further possible alternative embodiment, not shown in the figure, the packaging article  100  can provide that the flap  111  is fixed to the portion  121  in such a way that the flap  111  rests on the portion  121 , remaining inside the packaging article  100 . In particular said flap  111  is fixed to the portion  121  in such a way that the outer face  111   b  of the flap  111 , i.e. facing towards the outside of the packaging article  100 , rests on the inner face  121   b  of the portion  121 , i.e. facing towards the outside of the packaging article  100 . 
     Consequently, the female element  132  of the connection means  130  will be formed in the portion  121  of the sidewalls  120 , while the male element  131  will be carved on the extension flap  111 . 
     Also in this case the interlocking means  130  protrude facing towards the outside of the packaging article  100  and therefore do not hinder the insertion of the containers inside the tray  200  or the insertion of the cap  300  on the containers. In this solution, only the flap  111  remains inside the packaging article  100 , which in any case creates a reduced encumbrance being its thickness equal to that of the die-cut sheet  400 . 
     The spread out sheet  400  with characteristics such as to allow manufacturing the packaging article  100  according to the characteristics described above also forms the object of the invention. 
     The method for manufacturing a packaging article  100  by means of a sheet  400  of foldable material which provides for folding the sidewalls  110 ,  120  along fold lines  103  further forms an object of the invention. 
     Once folded, said sidewalls  110 ,  120  can be orthogonal or inclined with respect to the base wall  101 , for example with an inclination comprised between 45°-90°. 
     Said method provides for folding along the fold line  113  the extension flaps  111  which protrude from the ends  112  of said sidewalls  110 , arranging said extension flaps  111  in face-to-face relationship with a portion  121  of the adjacent sidewalls  120 . 
     Said method provides for fixing each extension flap  111  on the portion  121  by exerting a thrust action on the connection means  130  of the packaging article  100 , with a movement directed from the inside towards the outside of the packaging article  100 , and inserting the male element  131  inside the female element  132  so that a portion of said male element  131  projects from the female element  132  towards the outside of the packaging article  100 . 
     Said method provides for exerting the thrust action on the connection means  130  in a direction parallel and/or inclined with respect to the base wall  101 . 
     Furthermore, it provides for exerting a contrast action to retain the walls  120  and the flaps  111  in position during the thrust action on the connection means  130 . 
     Said method is applicable on tray forming machines both of the horizontal and vertical type known to a person skilled in the art. 
     The apparatus for manufacturing a packaging article  100  by means of a sheet  400  of foldable material which provides forming means for folding the sidewalls  110 ,  120  along fold lines  103  and folding along the fold line  113 , the extension flaps  111  which protrude from the ends  112  of said sidewalls  110 , arranging said extension flaps  111  in face-to-face relationship with a portion  121  of the adjacent sidewalls  120  forms the object of the invention. 
     The apparatus provides for fixing each extension flap  111  on the portion  121  by means of thrust devices  500  which act on the connection means  130  of the packaging article  100 . 
     Said thrust devices  500  are configured to insert the male element  131  inside the female element  132 , in particular in such a way that a portion of said male element  131  protrudes from the female element  132  towards the outside of the article of packaging  100 . 
     To do this, the thrust devices  500  preferably move in a direction which goes from the inside towards the outside of the packaging article  100 . 
     In particular, the thrust devices  500  exert the thrust action on the connection means  130  in a direction parallel and/or inclined with respect to the base wall  101 . 
     Said thrust devices  500  can comprise for example at least one actuator  501  of the for example electric, pneumatic, hydraulic type, etc. for the aforesaid movement. 
     Further, the thrust devices  500  can comprise sliders  502  whose shape is suitable for cooperating with the connection means  130  for fixing the extension flap  111  on the portion  121 . 
     Since the second zone  131   d  of the male element  131  has height B greater than the length A′ of the slit  132   a , the actuator  501  must act with sufficient force to ensure that the entire second zone  131   d  has passed the slit  132   a , when the packaging item  100  is formed. 
     According to an aspect of the invention, the thrust devices  500  are integral with the forming means. 
     According to a feature of the invention, the apparatus further comprises contrasting elements configured to retain the walls  120  and the flaps  111  in position during the movement of the thrust devices  500  on the connection means  130 , to carry out the insertion of the male element  131 , into the female element  132 . 
     Said thrust devices  500  are applicable on tray forming machines both of the horizontal and vertical type known to a person skilled in the art. 
     Thanks to said solution, the formation of the packaging article  100  does not require complex and expensive equipment. 
     It is understood however that what is described above has a value of non-limiting example, therefore, possible variants of detail that may be necessary for technical and/or functional reasons, are considered from now falling within the same protective scope defined by the claims indicated below.