Abstract:
A food packaging solution features a food-containing tray to be frictionally retained within an outer sleeve. External flanges of the tray are each resiliently flexible from a normal default condition into a down-turned condition bent more downwardly away from the open top end of the tray than in the normal default condition, and the sleeve is shaped and dimensioned to accommodate the tray between the opposing side walls of the sleeve only when the flanges of the tray are in the down-turned condition. When received inside the sleeve, the resilient flanges of the tray bias themselves upwardly in a spring-like manner forcing their distal outer ends into tighter frictional engagement with the sleeve walls.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to food packaging, and more particularly to food packaging of the type employing an internal food-containing tray and a packing sleeve in which the food-containing tray is received. 
       BACKGROUND 
       [0002]    It is well known in the food packaging industry to package food containers inside open-ended sleeves of paperboard or similar material, in which case some type of mechanism must be included for preventing the containers from sliding out of the cardboard sleeves until such time as the end consumer wishes to remove them. Prior techniques include the formation of slits in the side walls of the sleeve near the top panel of the sleeve, and dimensioning of the food container such that a portion of the container projects through these slits to the exterior of the sleeve, thus blocking sliding of the container out of the sleeve. Another known solution for packing of tin-can containers within a sleeve is to provide a partially cut-out portions in the top or bottom panel of the sleeve that are folded into the interior of the sleeve in order to block the rims of respective cans from sliding toward respective open ends of the sleeve. These solutions increase the shape-complexity of the paperstock blank from which the sleeve is formed. 
         [0003]    U.S. Pat. No. 5,900,264 discloses a food package tray that is sold inside a paperstock sleeve, which is described as either including score lines for removing a panel of the sleeve for access to the food tray by the end consumer, or employing a friction fit of the sleeve over the tray. However, no details on the friction fit are given, and there is potential concern about the strength of a friction fit relying solely on frictional contact of the inside of the paperstock sleeve with the thin peripheral edge of a rigidly stationary external flange of the tray. Particularly, there is potential concern over whether this would be sufficient to confidently retain the tray within the sleeve until such time as the end consumer desires to slide the tray free of the surrounding sleeve. 
         [0004]    Applicant has developed an improved friction fit between a food package tray and surrounding sleeve. 
       SUMMARY OF THE INVENTION 
       [0005]    According to a first aspect of the invention there is provided a food packaging apparatus comprising: 
         [0006]    a tray having a floor panel, a plurality of perimeter walls upstanding from the floor panel around a perimeter thereof including an opposing pair of perimeter side walls, an open top end delimited by the perimeter walls at upper ends thereof, and a pair of external flanges projecting outwardly from the opposing pair of the perimeter side walls; 
         [0007]    a sleeve having a base panel, an opposing upper panel, a pair of opposing side walls spanning upwardly from the base panel to the upper panel to support said upper panel at upper ends of said side walls that are spaced above the base panel in order to define an internal space that is bound between the base panel, the upper panel and the pair of opposing side walls and that has an open end for sliding receipt of the tray into said internal space; 
         [0008]    wherein the external flanges of the tray are each resiliently flexible from a normal default condition into a down-turned condition bent more downwardly away from the open top end of the tray than in the normal default condition, and the sleeve is shaped and dimensioned to accommodate the tray between the opposing side walls of the sleeve only with the flanges of the tray in the down-turned condition. 
         [0009]    According to a second aspect of the invention there is provided a food packaging apparatus comprising: 
         [0010]    a tray having a floor panel, a plurality of perimeter walls upstanding from the floor panel around a perimeter thereof including an opposing pair of perimeter side walls, an open top end delimited by the perimeter walls at upper ends thereof, and a pair of resiliently flexible external flanges projecting outwardly from the opposing pair of perimeter side walls; 
         [0011]    a sleeve having a base panel, an opposing upper panel, a pair of opposing side walls spanning upwardly from the base panel to the opposing upper panel to support said upper panel at upper ends of said side walls that are spaced above the base panel in order to define an internal space that is bound between the base panel, the upper panel and the pair of opposing side walls and that has an open end for sliding receipt of the tray into said internal space; 
         [0012]    wherein a dimension of each side wall of the sleeve measured between an internal corner at an intersection of said side wall with the upper panel and an internal corner at an intersection of said side wall with the lower panel is less than a dimension of the tray that is measured between an external corner at an intersection of the floor panel of the tray with a respective one of the opposing pair of perimeter side walls and a top corner of a respective one of the external flanges at a distal end thereof opposite said perimeter side wall with said flange in the normal default condition. 
         [0013]    When the tray is received within the internal space of the sleeve, preferably it is maintained therein purely by way of a frictional engagement between the sleeve and the flanges of the tray. 
         [0014]    According to a third aspect of the invention there is provided a method of providing a frictional fit between a tray and a sleeve in a food packaging apparatus, the method comprising: 
         [0015]    providing a pair of external flanges on the tray that project outwardly from an opposing pair of perimeter walls thereof and that are resiliently flexible from a normal default condition to a down-turned condition bent more downwardly away from an open top end of the tray than in the normal default condition to enable receipt of said tray within an internal space of the sleeve that will accommodate the tray therein when the external flanges in the down-turned condition, but not when the external flanges are in the normal default condition. 
         [0016]    According to a fourth aspect of the invention there is provided a method of providing a frictional fit between a tray and a sleeve in a food packaging apparatus, the method comprising: 
         [0017]    for a tray having a pair of external flanges thereon that projecting outwardly from an opposing pair of perimeter walls of the tray and that are resiliently flexible from a normal default condition to a down-turned condition bent more downwardly away from an open top end of the tray than in the normal default condition, providing a sleeve with an internal space shaped and sized to enable receipt of said tray when the external flanges in the down-turned condition, but not when the external flanges are in the normal default condition. 
         [0018]    According to a fifth aspect of the invention there is provided a method of providing a frictional fit between a tray and a sleeve in a food packaging apparatus, the method comprising: 
         [0019]    providing the tray and the sleeve with prescribed dimensions in which a dimension of each of two opposing side walls of the sleeve measured between an internal corner at an intersection of said side wall with an upper panel of the sleeve and an internal corner at an intersection of said side wall with a lower panel of the sleeve is less than a dimension of the tray that is measured between an external corner at an intersection of a floor panel of the tray with a respective one of two opposing perimeter walls of the tray and a top corner at a distal end of a respective one of two resiliently flexible flanges that project from said opposing perimeter walls of said tray when said external flanges are in a normal default position with the tray situated outside the sleeve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    One embodiment of the invention will now be described in conjunction with the accompanying drawings in which: 
           [0021]      FIG. 1  is an exploded perspective view of a food packaging assembly of the present invention featuring a food-containing tray to be housed within an outer sleeve. 
           [0022]      FIG. 2A  is an end elevational view of the sleeve of  FIG. 1 . 
           [0023]      FIG. 2B  is an an end elevational view of the food-containing tray of  FIG. 1 . 
           [0024]      FIG. 3  is an end elevational view of the food-containing tray and sleeve once assembled, and showing an improved friction fit provided between the tray and sleeve by resiliently flexible flanges of the tray that self-bias themselves tightly against side walls of the sleeve. 
       
    
    
       [0025]    In the drawings like characters of reference indicate corresponding parts in the different figures. 
       DETAILED DESCRIPTION 
       [0026]      FIG. 1  shows a food packaging assembly of the present invention featuring a food tray  10  and a paperstock sleeve  12  in which the food tray is to be received. The food tray may contain any of a number of possible food products therein, for example which may be sealed in an air-tight manner within the tray by a plastic film (not shown) sealed in place over the open top end of the tray. 
         [0027]    The tray features a planar rectangular floor panel  14 , four planar perimeter walls  16   a,    16   b,    16   c,    16   d  upstanding from the floor panel  14  at the four perimeter edges thereof. One opposing pair of these walls are referred to as perimeter side walls  16   a,    16   b,  and the other opposing pair are referred to as perimeter end walls  16   c,    16   d.  In the illustrated embodiment, all of the perimeter walls angle slightly outwardly from the floor panel  14  moving upwardly therefrom, and thus each having a trapezoidal shape in their respective planes. Other embodiments may, for example, having rectangular perimeter walls standing perpendicular to the floor panel  14 . A respective external flange  18   a,    18   b,    18   c,    18   d  projects outwardly from each perimeter wall  16   a,    16   b,    16   c,    16   d  at the top end thereof that lies opposite the floor panel  14 . 
         [0028]    When the tray  10  resides outside the sleeve  12 , as shown in  FIG. 1 , the flanges  18   a,    18   b,    18   c,    18   d  lie in a plane coplanar with the open top end of the tray and parallel to the floor panel  12 , which denotes a normal default position of the flanges  18   a,    18   b,    18   c,    18   d.  However, each flange is resiliently pliable, whereby it can flex upwardly and downwardly relative to this default position about the axis defined by its connection to the top edge of the respective perimeter wall  16   a,    16   b,    16   c,    16   d . An open top end of the tray is delimited by the top ends of the four perimeter walls  16   a,    16   b,    16   c,    16   d  for access to the food containing area located atop the floor panel  14  and bound on all four sides by the same perimeter walls. 
         [0029]    The sleeve features a planar rectangular upper panel  20 , an opposing planar rectangular base or bottom panel  22  spaced therefrom in generally parallel relation thereto, and a pair of planar rectangular side walls  24   a,    24   b  that each join the base panel  22  to the upper panel  20  at a pair of matching respective edges of these panels. A hollow interior space is delimited between the upper panel  20 , base panel  22  and side walls  24   a,    24   b,  and is left open at both ends thereof (i.e. at the two sides of the rectangular base and upper panels that are unoccupied by side walls  24   a,    24   b ). The sleeve has a wider upper panel than base panel, and so the side walls angle outwardly in the upward direction to give the hollow interior of the sleeve a trapezoidal shape bound by the four panels and walls. To assemble the food packaging assembly, the tray  10  is slid into the hollow interior of the sleeve  12  in an axial direction A that is parallel to the four corner edges of the sleeve (each corner edge referring where of one of the side walls  24   a,    24   b  joins with either the upper panel  20  or base panel  22 ). The trapezoidal shape of the sleeve is in cross-sectional planes lying normal to the axial direction A. 
         [0030]    With reference to  FIG. 2 , a dimension D 1  of the sleeve  12  is measured between the two inside corner edges of each side wall  24   a,    24   b,  or in other words, is measured between the intersection of the side wall with the base panel  22  and the intersection of the side wall with the upper panel  20 . With the tray situated outside the sleeve, and its flanges thus in their normal default positions, a dimension D 2  of the tray is measured between the outside corner edge at the intersection of the tray&#39;s floor panel  12  with either of the perimeter side walls  16   a,    16   b,  and the top corner edge of the respective flange  18   a,    18   b  at the distal end thereof furthest from the perimeter side wall  16   a,    16   b.  Although not necessarily reflected to scale in the drawings, D 1  is less than D 2 . As a result, the tray  10  will not fit into the hollow interior space of the sleeve  12  while the resiliently flexible flanges  18   a,    18   b  of the perimeter side walls  16   a,    16   b  of the tray  12  are in their normal default positions lying parallel to the floor panel  12  and coplanar with the open top of the tray. 
         [0031]    Still referring to  FIG. 2 , an upper width W 1  of the sleeve  12  is measured between the top inside corner edges of the two side walls  24   a,    24   b  where they intersect with the upper panel  20 . An upper width W 2  of the tray is measured between the distal ends of the two side flanges  18   a,    18   b  when the flanges are in their normal default state. The upper sleeve width W 1  closely conforms to the upper tray width W 2 . 
         [0032]    Due to the pliability of the perimeter side wall flanges  18   a,    18   b,  the tray can be accommodated within the sleeve  12  by flexing these flanges  18   a,    18   b  downwardly from their normal default positions of  FIG. 2  into the downturned positions shown in  FIG. 3 , where the flanges bend or curve downwardly from their normal plane at the top end of the tray toward the plane of the tray floor  14 . This down-turning of the side flanges  18   a,    18   b  reduces the distance from the bottom corner edge of the perimeter side wall  16   a,    16   b  to the top corner edge of the respective side flange  18   a,    18   b  to an amount that is equal or slightly less than dimension D 1  of the sleeve, whereupon the tray can now slide into the hollow interior of the sleeve  12  through one of the open ends thereof. With the tray received inside the sleeve, as shown in  FIG. 3 , the resiliency of the side flanges  18   a,    18   b  acts to bias the distal ends of the flanges upwardly back toward the plane of their normal default position. Moving generally arcuately about the axis of the upper edge of the perimeter side wall  16   a,    16   b  to which the flange  18   a,    18   b  is attached, the distal end of the flange is forced outwardly against the side wall  24   a,    24   b  of the sleeve  12  under this upward biasing of the flange toward its default state. 
         [0033]    The resiliently flexible flanges thus provide spring-like action against the side walls  24   a,    24   b  of the sleeve  12  in order to provide stronger frictional engagement between the tray and sleeve in order to better retain the two in the assembled state until such time as intention removal of the tray is desired, at which point pulling of the tray axially outward from the interior of the sleeve with sufficient manual force will slide the downturned flanges along the side walls of the sleeve until the tray is fully withdrawn from same, at which the time the resilient flanges will spring back upward toward their normal default state lying parallel to the tray floor  14  and coplanar with the tray opening. 
         [0034]    Like the internal upper width W 1  of the sleeve  12  at the upper panel  20  and the external upper width W 2  of the tray at the open top end thereof, the lower internal width W 3  of the sleeve  12  between the corner edges of the base panel  22  thereof is generally equal to the lower external width W 4  of the tray between the corresponding corner edges of the floor panel  14  so that the bottom corners of the sleeve and the tray generally line up with one another, which avoids the creation of excess floor panel area that would otherwise reach out from the under the tray and could potentially bend or curve upward to compensate for the shortened side wall dimension D 1  of the sleeve and accommodate straightening out of the resilient flanges  18   a,    18   b  inside the sleeve, which could potentially defeat the above described spring-like frictional interaction between the tray flanges and the sleeve. 
         [0035]    As various modifications can be made in my invention as described above, and many different embodiments may be made within the scope of the claims without departure from same, it is intended that all matter contained in the specification shall be interpreted as illustrative only and not in a limiting sense.