Patent Publication Number: US-2022227029-A1

Title: Method and mold for molding a foamed plastic foldable container, and container manufactured thereby

Description:
CROSS-REFERENCE TO CO-RELATED PATENT APPLICATIONS 
     This application claims the priority of the Italian patent application no. 102019000007020 filed on 20 May 2019, the content of which is incorporated herein as reference. 
     TECHNICAL FIELD 
     The present invention relates to a method and to a mold for molding a foamed plastic foldable container, and to the container manufactured thereby. 
     STATE OF THE PRIOR ART 
     In particular, the present invention relates to a foldable container made of foamed plastic, for example polypropylene, polyethylene, polystyrene and their copolymers, of the type described in the document WO-A-2012028567. 
     The container has a parallelepiped shape, and comprises a first wall substantially flat, a pair of mutually facing second walls hinged to the first wall, and a pair of mutually facing third walls also hinged to the first wall. 
     The container can assume an upright working configuration, wherein the second walls and the third walls are in an upright configuration, i.e. the second walls are parallel to one another and perpendicular to the first wall and the third walls are parallel to one another and perpendicular to the first wall and to the second walls to allow the use of the container, and a flattened folded configuration, wherein the first wall, the second walls, and the third walls are mutually parallel and overlapping to reduce the size of the container and allow its transport and storage. 
     In the upright configuration, the container is cup-shaped and is closed by a lid mounted and blocked in a releasable manner on the second walls and on the third walls. 
     Since the closing of the known foamed plastic foldable containers of the type described above involves the use of a first mold for the manufacturing of the containers, the use of a second mold for the manufacturing of the lids, and the storage of both the containers and the lids, such containers are relatively complex and costly and involve relatively high management costs. 
     OBJECT OF THE INVENTION 
     The object of the present invention is to manufacture a mold for molding foamed plastic foldable containers which resolves the drawbacks described above and which is easy and economical to implement. 
     According to the present invention, a mold for molding foamed plastic foldable containers is manufactured according to what claimed in claims from  1  to  7 . 
     Moreover, the present invention relates to a method for molding foamed plastic foldable containers. 
     According to the present invention, a method for molding foamed plastic foldable containers is provided according to what claimed in claims from  8  to  14 . 
     Finally, the present invention relates to a foamed plastic foldable container. 
     According to the present invention, a foamed plastic foldable container is manufactured according to what claimed in claims from  15  to  19 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the attached drawings, which illustrate a non-limiting embodiment, wherein: 
         FIG. 1  is an exploded perspective view of a preferred embodiment of the mold and of the container according to the present invention; 
         FIG. 2  is a first cross-sectional schematic view, with parts removed for the sake of clarity, of the mold of  FIG. 1 ; 
         FIG. 3  is a second cross-sectional schematic view, with parts removed for the sake of clarity, of the mold of  FIG. 1 ; 
         FIG. 4  is a schematic perspective view, with parts in cross-section and parts removed for the sake of clarity, of a detail of the mold of  FIG. 1 ; 
       Figures from  5  to  8  are four schematic views in cross-section, with parts removed for the sake of clarity, of a detail of the mold of  FIG. 1  illustrated in four different working positions; 
         FIGS. 9 and 10  are four schematic perspective views of the container of  FIG. 1  illustrated in different configurations. 
     
    
    
     PREFERRED EMBODIMENT OF THE INVENTION 
     With reference to  FIGS. 1, 9, and 10 , reference number  1  refers, in its whole, to a mold designed to be installed in a machine (not illustrated) for molding foamed plastic, for instance polypropylene, polyethylene, polystyrene and their copolymers, for the manufacturing of a foldable container  2  having the shape of a parallelepiped box and configured for housing products (not illustrated) of a varied nature inside therein. 
     The container  2  comprises a substantially rectangular first wall  3 ; two mutually facing second walls  4  rotatably coupled to the wall  3  at respective connection hinges  5 ; two mutually facing third walls  6  rotatably coupled to the wall  3  at respective connections hinges  7  which are transverse to the hinges  5 ; and a closing wall  8 . 
     According to the preferred embodiment illustrated in the attached Figures, the wall  8  comprises two panels  9 , each of which is rotatably coupled to a corresponding wall  4  at a respective connection hinge  10 . According to a variant not illustrated, the wall  8  can be monolithic and hinged to one of the walls  4 . 
     According to the illustrations shown in  FIGS. 9 a , 9 b , 10 b  and 10 b   , the container  2  can assume a working or upright configuration ( FIG. 9 a   ), wherein the walls  4  are parallel to one another and perpendicular to the wall  3 ; the walls  6  are parallel to one another and perpendicular to the walls  3  and  4 ; and the wall  8  is movable between a closing position of the container  2 , wherein the wall  8  faces and is parallel to the wall  3 , and an opening position of the container  2 , wherein the wall  8  is turned outwards in order to leave the entry opening of the container  2  free. 
     In particular, in the opening position of the container  2 , the panels  9  can assume the position illustrated in  FIG. 9 b    or positions turned more towards the respective walls  4  to which they are hinged, up to a maximum rotation position, wherein each panel  9  is in contact with the respective wall  4  ( FIG. 10 a   ). 
     In particular, in the closing position of the container  2 , the panels  9  of the wall  8  are arranged in contact with the walls  4  at respective coupling faces  11 , which are arranged on opposite sides of, and contiguous with, the hinge  10  and are inclined with respect to larger faces  12  of the walls  4  and panels  9 . 
     According to the illustration shown in  FIG. 9 b   , the face  11  obtained on the panel  9  is contiguous with the inside face  12  of the panel  9 , i.e. with the face  12  which, in the closing position of the container  2 , is turned towards the inside of the container  2 , and the face  11  obtained on the panel  4  is contiguous with the inside surface  12  of the wall  4 . 
     Advantageously, moreover, the faces  11  are inclined with respect to the respective surfaces  12  of an angle such that the faces  11  are coplanar in the opening position of the container  2  illustrated in  FIG. 9 b   , which, as will become evident in the following, is a position of deformation of the container  2  by the mold  1 . 
     Furthermore, the container  2  can take a folded or flattened configuration ( FIG. 10 b   ), wherein the walls  6  are folded onto the wall  3 , the walls  4  are folded onto the walls  6 , and the panels  9  are folded onto the walls  4 . 
     Advantageously, according to the illustrations shown in  FIGS. 9 a  and 9 b   , each panel  9  is blocked in a releasable manner in its closing position by means of the engagement of a protrusion  13  obtained on the face  11  of the corresponding wall  4  parallel to the corresponding hinge  10  in a recess  14  obtained on the face  11  of the panel  9  and the engagement of a protrusion  15  obtained on each wall  6  parallel to the corresponding hinge  7  in a recess  16  obtained on the face  12  of the panel  9 . 
     The mold  1  comprises two half-molds  17  and  18  movable with respect to one another and towards a working molding position, wherein the half-mold  17  extends inside the half-mold  18  and the two half-molds  17  and  18  are coupled to one another in a fluid-tight manner to define a molding chamber  19  having the shape of the container  2  in its upright configuration and with the panels  9  arranged in their opening positions. 
     The half-mold  18  has the shape of a box-like body and comprises a bottom floor  20 , two lateral walls  21  perpendicular to the wall  20 , and two lateral walls  22  perpendicular to the walls  20  and  21 . 
     Furthermore, according to the illustrations shown in  FIGS. 1, 2, and 3 , the half-mold  18  comprises two upper walls  23 , which protrude outside the walls  21 , are perpendicular to the walls  21 , and define, together with the corresponding walls  21 , respective upper edges  23   a.    
     The half-mold  17  has the shape of a box-like body and comprises a bottom floor  24 , two lateral walls  25  perpendicular to the wall  24 , and two lateral walls  26  perpendicular to the walls  24  and  25 . 
     The half-mold  17  further comprises two upper walls  27 , which protrude outside the walls  25 , are perpendicular to the walls  25 , and are each connected to a corresponding wall  25  by the interposition of a joining wall  27   a.    
     The wall  27   a  is inclined with respect to the walls  25  and  27 , preferably but not necessarily at an angle of substantially 45°, and is coplanar with the corresponding edge  23   a.    
     The half-mold  17   b  is further provided at each edge defined between each pair of mutually adjacent walls  25 ,  26 , with a corresponding dividing flap  28 , which protrudes outside the half-mold  17 , and extends between the two half-molds  17  and  18  to separate each wall  4  of the container  2  from the adjacent wall  6 . 
     Furthermore, the mold  1  comprises a first forming assembly  29  configured to form the hinges  5  and  7  and a second forming assembly  30  configured to form the hinges  10 . 
     The forming assembly  29  comprises, for each hinge  5 ,  7 , a respective forming unit  31  comprising, in turn, a parting device  32  mounted outside the half-mold  18  and a compression device  33  mounted inside the half-mold  17  to cooperate with the parting device  32 . 
     With reference to  FIGS. 2, 3, and 4 , the device  32  comprises a blade  34 , which extends along the corresponding hinge  5 ,  7  parallel to the wall  3 , is substantially coplanar with the corresponding hinge  5 ,  7 , and is engaged in a sliding manner through the corresponding wall  21 ,  22 . 
     The blade  34  is moved by actuating cylinders  35  fixed to the half-mold  18  between a rearward position (not illustrated), wherein the blade  34  is arranged outside the chamber  19 , and a forward position ( FIGS. 2, 3, 4 ), wherein the blade  34  extends inside the chamber  19 . 
     The device  33  comprises a buffer  36 , which extends along the corresponding hinge  5 ,  7 , is inclined with respect to the corresponding wall  25 ,  26 , and is limited by an end face  37  parallel to an outside face  38  of the corresponding wall  25 ,  26 . 
     The buffer  36  is engaged in a sliding manner through the corresponding wall  25 ,  26 , and is moved by actuating cylinders  39  fixed to the half-mold  17  between a rearward position (not illustrated), wherein the buffer  36  extends outside the chamber  19  and limits inside the corresponding wall  25 ,  26  a variable-volume chamber (not illustrated) connected to the chamber  19 , and a forward position ( FIGS. 2 and 3 ), wherein the face  37  is arranged substantially coplanar with the face  38  of the corresponding wall  25 ,  26 . 
     According to the illustrations shown in  FIGS. 5, 6, 7, and 8 , the forming assembly  30  comprises, for each hinge  10 , a respective forming unit  40  comprising, in turn, a parting device  41  and a compression device  42  mounted on one of the two half-molds  17  or  18  and configured to cooperate with each other. In the example illustrated in the attached figures, the parting device  41  and the compression device  42  are mounted on the wall  27   a  of the half-mold  17 . 
     The device  42  comprises a compressor  43 , which preferably has the shape of a parallelepiped bar, extends along the corresponding hinge  10 , and is limited by a substantially flat end face  44 . 
     The compressor  43  engages the corresponding wall  27   a  in a sliding manner to define, together with the wall  27   a , a variable-volume chamber  45 , which extends on opposite sides of the corresponding edge  23   a , and communicates with the molding chamber  19 . 
     The compressor  43  is moved by two mutually parallel actuating cylinders  46  in a forward direction  47  perpendicular to the wall  27   a  from and towards a forward position ( FIGS. 7 and 8 ), wherein the face  44  is arranged substantially in contact with the edge  23   a  and the chamber  45  has a volume substantially equal to zero, and a rearward position ( FIGS. 5 and 6 ), wherein the chamber  45  has its maximum volume. 
     With respect to the foregoing statements, it should be specified that: 
     when the compressors  43  of the two forming units  40  are simultaneously arranged in their forward positions, the chamber  19  is divided into a lower portion  19   a  having the shape of the walls  3 ,  4 , and  6  and into two upper portions  19   b  each having the shape of a panel  9  of the wall  8 ; and when the compressors  43  of the two forming units  40  are arranged simultaneously in their rearward positions, the portion  19   a  communicates with the portions  19   b  by means of the corresponding chambers  45 . 
     The device  41  comprises a blade  48 , which extends along the corresponding hinge  10 , is parallel to the direction  47 , and is aligned with the edge  23   a  in the direction  47 . 
     The blade  48  is arranged on the same side of the compressor  43 , relative to the chamber  19 , and is engaged in a sliding manner through the compressor  43  in order to define, together with the compressor  43 , a variable-volume chamber  49  communicating with the chamber  19 . 
     The blade  48  is moved by two mutually parallel actuating cylinders  50  in the direction  47  between a rearward position ( FIG. 5 ), wherein the chamber  49  has its maximum volume and the portion  19   b  communicates with the portion  19   a  by means of the chamber  49 , and a forward position ( FIGS. 6 and 8 ), wherein the blade  48  is arranged substantially in contact with the edge  23   a , the chamber  49  has a volume substantially equal to zero, and the portion  19   b  is substantially separate from the portion  19   a.    
     The operation of the mold  1  will now be described with reference to  FIGS. 2  and from  5  to  8  and as of a moment when ( FIG. 6 ): 
     the two half-molds  17  and  18  are arranged in the molding working position and form the chamber  19  therebetween; 
     the compressor  43  of each forming unit  40  is arranged in its rearward position; and 
     the blade  48  of each forming unit  40  is arranged in its forward position. 
     When the compressor  43  of each forming unit  40  is arranged in its rearward position and the corresponding blade  48  is arranged in its forward position, the corresponding portion  19   b  is separated from the portion  19   a  and the corresponding chamber  45  is divided into two portions  45   a ,  45   b  connected to the portion  19   a  and, respectively, to the corresponding portion  19   b.    
     The plastic material is then fed into the portions  19   a  and  45   a  and into the portions  19   b  and  45   b  to form the walls  3 ,  4 , and  6  and the panels  9  of the wall  8 . 
     In this regard, since each blade  48  separates the section defined by the portion  19   a  and by the corresponding portion  45   a  from the section defined by the corresponding portions  19   b  and  45   b , the plastic material fed into the portions  19   a  and  45   a  can be different from the plastic material fed into the portions  19   b  and  45   b . In this way, the panels  9  of the closing wall  8  can be different, for example in colour, from the walls  3 ,  4 , and  6  of the container  2 . 
     Following, the hinges  5  and  7  are formed by the forming units  31  of the forming assembly  29  by combining the action of the blades  34  with the action of the buffers  36  as described and illustrated in the European patent EP-3057759-B1 incorporated here in its entirety as reference. 
     According to the illustrations shown in  FIGS. 7 and 8 , each hinge  10  is formed: 
     by moving the corresponding compressor  43  into its forward position to push into the portion  19   a  the plastic material contained in the corresponding portion  45   a  and push into the portion  19   b  the plastic material contained in the corresponding portion  45   b  and 
     by moving the corresponding blade  48  first into its rearward position to allow the plastic material to enter into the corresponding chamber  49  and, then, towards its forward position to compress the plastic material contained in the chamber  49  and form the hinge  10 . 
     With respect to the foregoing statements, it should be specified that, when the compressors  43  are moved into their forward positions and the blades  48  are moved first from their forward positions into their rearward positions and then from their rearward positions towards their forward positions, the plastic material is subjected to a flow of steam injected into the portion  19   a  and into the portions  19   b.    
     Therefore, the compression of the plastic material contained in the portions  45   a  and  45   b  against the areas of the portion  19   a  and, respectively,  19   b  contiguous with the edge  23   a  occurs during the vaporization phase of the plastic material; analogously, the compression of the plastic material contained in the chamber  49  against the edge  23   a  occurs during the vaporization phase of the plastic material. This allows obtaining along, and on either side of, the edge  23   a  a higher-density area which makes the resulting hinge  10  particularly robust and capable of resisting a substantially unlimited number of openings/closings of the corresponding panel  9  during the lifetime of the container  2 . 
     The mold  1  has some advantages mainly deriving from the fact that, at the end of the molding process, the container  2  is complete and provided with the closing wall  8  and, thus, does not involve the management, the storage, and the assembly of mutually separate pieces. 
     Moreover, the forming assembly  30  not only allows manufacturing an extremely robust hinge  10  along the edge  23   a  which connects the panels  9  to the rest of the container  2 , but it advantageously allows manufacturing the closing wall  8  with a different type of material, in particular of a different colour, than that of the other walls of the container. In the case of the illustrated example, wherein the closing wall  8  is composed of two panels  9 , the latter can be manufactured in the same colour or in a different one. This is possible due to the fact that the forming assembly  30 , in particular the parting device  32 , creates, during the feeding of the material into the molding chamber  19 , a clear separation between the portion  19   b  of the molding chamber  19  intended to form the closing wall  8 , i.e. the panels  9 , and the portion  19   a  of the molding chamber  19  intended to form the walls  3 ,  4  and  6 . 
     The description relating to the closing wall  8  is also valid, mutatis mutandis, for the other walls of the container  2 . In other words, it is possible to associate a forming assembly  30  also with the hinges that connect the walls  4  and the walls  6  to the bottom floor  3 . This way, it is possible to manufacture a container  2  having some or all the walls  3 ,  4 ,  6  and  8  in different colours between each other.