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.

What is claimed is:  
     
         1 . A container, comprising: 
 a wall panel made of sheet material, bounding an inner volume of the container, wherein said wall panel is movably expandable into the inner volume of the container during a phase of erection of the container;    an inside flap made of sheet material, arranged substantially perpendicular to the panel bounding the inner volume, the inside flap extending across at least part of the inner volume;    wherein the inside flap initially has clearance relative to the wall panel for insertion of the inside flap, and the wall panel is movable to engage against the inside flap after insertion of the inside panel.    
     
     
         2 . The container of  claim 1 , wherein the inside flap is integrally coupled to a further wall panel adjacent to said wall panel that is movably expandable.  
     
     
         3 . The container of  claim 2 , comprising a pair of opposite said wall panels, each being movably expandable into the inner volume, and a pair of opposite said inside flaps, each being coupled to one of two said further wall panels that extend between the opposite said wall panels.  
     
     
         4 . The container of  claim 1 , wherein the wall panel is an inner panel of a hollow wall further comprising an outer panel a top ledge and an in-fold flap.  
     
     
         5 . The container of  claim 4 , wherein the in-fold flap is an outer in-fold flap, and wherein the outer in-fold flap, the inner and outer panels and the top ledge form a collapsed parallelogram that is opened by folding-in the outer in-fold flap.  
     
     
         6 . The container of  claim 5 , wherein the inner panel is an integral extension of at top edge of a sidewall of the container, the outer in-fold flap is an integral extension at a bottom edge of said sidewall, and the inner in-fold flap is an integral extension at a bottom of an adjacent sidewall of the container.  
     
     
         7 . A container made of sheet material, comprising: 
 a plurality of wall panels connected along corner folds, the wall panels including two pairs of opposite spaced wall panels, one of said two pairs being front and rear wall panels, and the other of said two pairs being opposite spaced end wall panels perpendicular to the front and rear wall panels;    two sets of opposite in-fold flaps coupled respectively to an edge of one of the pairs of opposite spaced wall panels, one of said sets of in-fold flaps being outer in-fold flaps and the other of said sets being inner in-fold flaps, the inner in-fold flaps being foldable into a position between inner surfaces of the other of the pairs of opposite spaced wall panels;    wherein said other of the pairs of opposite spaced wall panels comprises two spaced panels forming part of a parallelogram with the outer in-fold flaps, whereby folding-in of the outer in-fold flaps separates the two spaced panels to provide an inwardly expanding hollow wall, and wherein an inner surface of the hollow wall bears against the inner in-fold flaps.