Paperboard container having in-fold panel engaged between expanding walls during erection

Abstract

A container of paperboard, corrugated craft paper or the like is provided with one or more walls that moves inwardly with erection of the container and bears against an in-fold flap of an adjacent wall, to square up and reinforce the container. In one arrangement, two opposite hollow walls of a rectilinear container expand inwardly against two inner in-fold flaps, during folding of outer in-fold flaps associated with the two hollow walls, into a position in the plane of the container bottom. Embodiments are disclosed with variations including multiple plies, center dividers, integral lid panels and tear-outs. The container preferably is produced in a knocked down flat shape with four sidewalls folded flat on one another. The container is erected into a rectangular shape by pressing its diagonally opposite corners toward one another. The inner in-fold flaps first are folded up into the plane of the container bottom, which can be done with ample clearance because the adjacent hollow walls are at first flat and retracted. The outer in-fold flaps have a parallelogram connection with the inner and outer panels of the hollow walls, causing the inner one of the panels to move inwardly against the inner in-fold flaps, eliminating the clearance as the outer in-fold flaps are rotated into the plane of the container bottom.

Dependencies are inferred from the claim text.