Contoured clamshell container

Abstract

A clamshell container comprising a tray and a cover formed from a blank; the tray including a bottom and four curved side walls foldable upward from the four edges of the bottom along arcuate fold lines, the tray walls having defined corners inwardly offset relative to the center points of the walls; and a cover provided with corresponding walls, at least three of which are folded from arcuate fold lines along corresponding edges of a cover top panel and which define depending arcuate cover walls and a cover with a maximum width at transverse centerlines between opposed sets of walls and minimum widths at corners defined by the cover walls; the cover pivotally closing over the tray with the arced walls of the tray received within the arced walls of the cover and engaging therewith.

1 . A clamshell container of foldable paperboard particularly adapted for reception of a heated foodstuff, said container being configured for reduced utilization of paperboard and enhanced retention of heat, said container comprising a tray and a cover, each of generally rectangular configuration, said tray having a bottom with opposed side edges and opposed front and rear edges, said tray further including opposed laterally spaced front and rear walls folded upwardly respectively from said front and rear edges of said tray bottom, the laterally spaced relation between said front and rear walls being at a maximum at aligned opposed central sections of said front and rear walls, said front and rear walls having opposed end sections inwardly of the respective central sections and defining, relative to the space between the central sections, a reduced spacing between aligned and opposed respective end sections of said front and rear walls for close accommodation of said front and rear walls to a received foodstuff, said tray further including opposed laterally spaced side walls folded upward respectively from said opposed side edges of said tray bottom, the laterally spaced relation between said side walls being at a maximum at opposed central sections of said side walls, said side walls each having opposed end sections inward of the respective central sections and defining a reduced spacing at opposed respective end sections of said side walls for close accommodation of the side walls to a received foodstuff, said side walls at opposed ends thereof, joining to and forming corners with corresponding ends of said front and rear walls to define corners inwardly offset relative to said maximum spaced central sections and restricted corner air spaces within said tray for minimizing heat loss from a received heated foodstuff. 
   
   
       2 . The clamshell carton of  claim 1  wherein said tray walls each follow a constant arc along the corresponding edge of the tray bottom. 
   
   
       3 . The clamshell container of  claim 2  wherein said front, rear and side walls have upper edges and incline outward from said bottom to said upper edges. 
   
   
       4 . The clamshell container of  claim 3  wherein the edges of the tray bottom are defined by convex fold lines about which the walls fold upwardly and which define the arcs of the walls. 
   
   
       5 . The clamshell container of  claim 4  wherein said front and side walls maintain said constant arc from said tray bottom to the upper edges thereof, the arc of said rear wall at the corresponding edge of the tray bottom progressively decreasing upward from said tray bottom to the upper edge of said rear wall. 
   
   
       6 . The clamshell container of  claim 5  wherein said container cover includes a cover top defined by laterally spaced opposed side edges and laterally spaced opposed front and rear edges, opposed laterally spaced cover side walls folded from said top side edges, and opposed laterally spaced front and rear cover walls folded from said front and rear edges of said cover top, said front edge and said side edges of said cover top each being defined by a convex fold line about which the corresponding walls fold, said cover side and front walls being convex relative to said cover top with the arc of each of these walls being defined by the corresponding fold line between the wall and the top. 
   
   
       7 . The clamshell container of  claim 6  wherein said rear edge of said cover top is defined by a straight fold line, said cover rear wall being planar. 
   
   
       8 . The clamshell container of  claim 7  wherein said tray rear wall and said cover rear wall have common outer edges joined along a straight fold line providing hinge means between said cover and said tray for a selective closing of said cover over said tray. 
   
   
       9 . The clamshell container of  claim 8  wherein, upon a closing of said cover over said tray, said cover side and front walls overlie said tray side and front walls in intimate contact with the upper edges of said tray side and front walls, said cover front wall being of a substantially greater height than said tray front wall. 
   
   
       10 . A clamshell container formed of foldable paperboard and comprising a tray and a cover, said tray comprising a bottom panel with opposed side edges and opposed front and rear edges, a pair of transversely spaced side walls integral with and folded from said opposed side edges of said bottom panel along convex side fold lines, each side fold line defining an arcuate configuration to the corresponding side wall above said bottom panel, said tray further including transversely spaced front and rear walls respectively integral with and folded from the opposed front and rear edges of said bottom panel along a convex front fold line and a convex rear fold line, said front and rear fold lines defining an arcuate configuration to each of said front and rear walls above said bottom panel, said cover comprising a top panel, said top panel having opposed side edges and opposed front and rear edges, a pair of opposed transversely spaced cover side walls and a cover front wall integral with and folded from corresponding side and front edges of said top panel along fold lines convex relative to said top panel, and a cover rear wall opposed to and transversely spaced from said cover front wall, said cover rear wall being integral with and folded from a linear fold line defining said rear edge of said top panel, said tray rear wall and said cover rear wall having a common outer edge defined by a linear fold line forming a hinge joinder between said tray and said cover for selective closing of said cover over said tray. 
   
   
       11 . The clamshell container of  claim 10  wherein the transverse spacing between the walls of each pair of opposed walls of both the tray and the cover is at a maximum at the central point of each wall with this transverse spacing decreasing between each pair of opposed walls toward opposite ends of the walls of each pair of opposed walls, whereby the transverse spacing between corresponding ends of each pair of opposed walls is less than the transverse spacing between the corresponding center points of the same pair of opposed walls. 
   
   
       12 . The clamshell container of  claim 11  wherein the ends of each tray wall are joined to adjacent ends of adjoining walls to form four corners about said tray bottom, each corner defining an included angle of greater than 90°. 
   
   
       13 . A container blank foldable to define a tray and cover, said blank including a tray section and an aligned cover section, said tray section having a central bottom panel defined by a pair of opposed convex side wall fold lines, a convex front wall fold line and an opposed convex rear wall fold line, a pair of opposed side wall panels integral with said bottom panel and foldable relative thereto along said side wall fold lines, a front wall panel and a rear wall panel integral with said bottom panel and foldable relative thereto respectively along said front and rear wall fold lines, each convex wall fold line being at a transverse spacing from the opposed fold line which is at a maximum at transversely aligned center points of the opposed fold lines and which progressively decrease outward from the central points to a minimum spacing at transversely aligned ends of the opposed fold lines. 
   
   
       14 . The blank of  claim 13  wherein said cover section has a central top panel defined by a pair of opposed convex side wall fold lines, a front wall fold line and an opposed rear wall fold line, a pair of opposed cover side wall panels integral with said top panel and foldable relative thereto along said top panel side wall fold lines, a cover front wall panel and a cover rear wall panel integral with said top panel and foldable relative thereto respectively along the front and rear top panel fold lines. 
   
   
       15 . The blank of  claim 14  wherein said top panel front wall fold line is convex. 
   
   
       16 . The blank of  claim 15  wherein said cover rear wall fold line is linear, each cover convex wall fold line being at a transverse spacing from the opposed fold line which is at a maximum at transversely aligned center points of the opposed fold lines and which progressively decrease outward from the center points to a minimum spacing at transversely aligned ends of the opposed fold lines. 
   
   
       17 . The blank of  claim 16  wherein said rear wall panels of said tray section and said cover section have a common linear outer edge defined by a hinge-forming linear fold line. 
   
   
       18 . The blank of  claim 17  wherein said tray front wall panel has a concave arc outer edge, said cover front wall panel having a convex arc outer edge complementing the concave arc of the tray front wall panel outer edge. 
   
   
       19 . The blank of  claim 18  wherein the cover front wall is of a transverse width greater than that of the tray front wall panel to define an enhanced display surface in a folded container. 
   
   
       20 . The blank of  claim 19  wherein said tray side wall panels have arced outer edges, said cover side walls panels having arced outer edges complementing the arcs in the outer edges of the tray side wall panels for a simultaneous defining of these outer edges between duplicate blanks when simultaneously cutting multiple blanks.