Fiberboard flat with joined strengthened corners for setting up into an angular tray and the set-up tray

Claim 1

A flat for use in setting up a tray-like article which has a substantially flat wall with side walls at its periphery that are angularly disposed relative to each other and are connected at the angular joints there-between said flat comprising: a substantially flat wall portion of angular peripheral outline having scored fold lines adjacent all its edges; side-wall producing flaps attached to said flat wall portion around its periphery at the respective scored fold lines and having opposed ends; said flaps comprising first and second flaps alternating around the periphery of said flat wall portion with the first flaps extending outwardly from their respective scored fold lines in a substantially common plane with said flat wall portion and with the second flaps turned inwardly about their respective scored fold lines into overlapping relationship with said flat wall portion; and joint structures for connecting together adjacent ends of said first and second flaps and comprising: an outwardly extending tab on the end of the second flap; an inwardly folded connecting section on the adjacent end of the first flap carrying an inwardly extending tab which is in superimposed relationship and in flat contact with said second flap and being secured thereto; said outwardly extending tab extending outwardly in superimposed relationship and in flat contact with the said connecting section and being secured thereto; said outwardly extending tab being connected to said second flap at a scored joint fold line and said inwardly extending tab being connected to said connecting section at a scored joint fold line, the two scored joint fold lines being superimposed to provide a common joint fold line; said common joint fold line being in alignment with the fold line of said first flap which is a scored line; said connecting section being folded inwardly about a scored fold line at an angle relative to said common joint fold line; said inwardly extending tab extending beneath the second flap, being provided with an inner edge extending angularly from said corner fold line and being provided with an inward extension beyond the angular edge; said common joint scored fold lines being more pronounced than the other said scored fold lines; said flat wall portion being of quadrangular outline and the flaps being provided as opposed pairs of the first and second flaps with the flaps of the first pair extending outwardly in opposite directions and the flaps of the second pair extending inwardly towards each other, said angular scored fold line Being at an angle of 45* relative to said corner joint fold line, said outwardly extending tab having an outer edge disposed at an angle less than 45* relative to said common joint fold line so that said edge will be recessed inwardly of said angular scored fold line of said connecting section, said angular inner edge of said inner tab also being disposed at an angle of 45* relative to said corner fold line.