Corner post

An elongated corner post for use between the vertical corners of containers and products packaged therein consisting essentially of an integral rectangular tube and attached leg prepared from a single blank of paperboard or the like, said blank being of substantially rectangular configuration and divided along one of its dimensions by a plurality of parallel fold lines into a plurality of discrete panels of unequal width, at least two of said panels being arranged in overlapping engagement and secured to one another, the improvement wherein the formed corner post is normally stored and shipped in a substantially flat condition and manually erected into the tube and leg configuration at the point of use.

BACKGROUND OF INVENTION 
The present invention relates to the field of packaging and more 
particularly, it relates to corner posts that are used in containers for 
the purpose of cushioning and protecting products shipped in the 
containers from damage caused by external forces. 
It is customary to package bulky and heavy products in relatively 
lightweight but strong paperboard containers. However, during 
transportation, storage and handling of the packaged products the 
lightweight containers are subject to damage. Moreover, the vertical 
stacking strength of lightweight containers is not very great. Thus, 
damage can also occur to the packaged products when the containers are 
stacked high, either in a warehouse or in a transportation vehicle. 
To overcome some of the problems inherent with lightweight containers, it 
is customary to add corner posts to the containers. When provided at the 
corners of a container, the corner posts provide excellent stacking 
strength, and because the corner posts provide a space between the side 
walls of the container and the packaged product, damage from external 
blows is substantially reduced. 
DESCRIPTION OF PRIOR ART 
The art of corner post design is well developed as represented by the 
disclosures of the following United States Pat. Nos.: 3,072,313; 
3,613,985; 3,734,389; 3,780,929. 
However, a careful analysis of the patented corner posts will show that 
most prior art designs take the form of completely formed structures that 
are hard to handle and store, or the form of unfinished blanks from which 
the corner posts are built on site. For instance, the FIG. 4 corner post 
disclosed in U.S. Pat. No. 3,072,313 is bulky to handle and store. 
Meanwhile, the corner posts disclosed in U.S. Pat. No. 3,613,985 require 
considerable labor to set up which is generally unacceptable to the 
customer. 
In contrast to these prior efforts, the corner post of the present 
invention provides the user with a completely formed structure that needs 
only to be manipulated at the point of use to achieve its workable 
configuration. Moreover, the corner post of the present invention includes 
a provision wherein a part of the tubular portion thereof can be collapsed 
to clear handles, knobs or other projections on the surface of the 
packaged object.

SUMMARY OF INVENTION 
The corner post of the present invention consists of an integral 
rectangular tube and leg prepared from a single blank of paperboard or the 
like with only two folds and a single glue lap. The leg portion of the 
corner post is arranged to fit between one of the side walls of the 
container in which it is used and the packaged product, while the tube 
portion of the corner post is arranged to fit into the corner of the 
container to provide a cushioning space between the packaged product and 
an adjacent side wall of the container. 
Corrugated paperboard is the preferred material for the corner post blank 
and generally the blank is formed from several layers of paperboard 
(corrugated medium and linerboard) to produce a corner post of adequate 
strength. The corrugated material may be that conventionally used in 
forming containers or it may be impregnated or coated with a suitable 
moisture barrier material to resist the penetration of water. The corner 
post blank is divided by a plurality of fold lines (at least five) to 
produce a plurality of panels (at least six) each of which have different 
widths. The width of each individual panel may vary over a perscribed 
range but for the sake of the present invention, the variance in the width 
of each panel does not exceed a point which would prevent the folded and 
glued blank from being folded flat for shipment and storage. Thus, an 
important feature of the present invention lies in the fact that the fully 
assembled corner post can be folded flat for shipment to its point of use 
and then easily erected for use simply by manipulating the folded blank to 
form the rectangular tube portion of the corner post. Once the corner post 
is erected and inserted in a container between the container said ealls 
and the packaged product, it retains its shape as a result of being wedged 
into position. The corner post provides vertical stacking strength to the 
container both because of its shape and construction and also serves to 
provide a void space between the container side walls and the packaged 
product. Another important feature of the present invention is the 
provision whereby by applying selected cuts to the blank material, one or 
more parts of the erected tubular portion of the corner post can be 
collapsed to avoid knobs, handles or other projections on the packaged 
product. 
DETAILED DESCRIPTION 
Referring to the drawings, particularly FIGS. 1 and 1A, each illustrates a 
blank 20 of foldable sheet material, such as fiberboard, and more commonly 
multi-ply layers of corrugated paperboard, that can be used to fabricate 
the corner post of the present invention. The blank is of substantially 
rectangular configuration and is divided into a plurality of panels 
1,2,3,4,5 and 6 by a series of parallel fold lines 7,8,9,10 and 11. The 
scored fold lines 8,9,10 and 11 are preferably applied to one face of the 
blank while score line 7 is applied to the opposite face of the blank to 
facilitate the folding sequence of the blank. In addition, it is preferred 
that score lines 9,10 and 11 consist of alternating cuts and scores (or 
indentations) to further facilitate folding particularly where the blanks 
are formed of several layers of corrugated paperboard. The scored fold 
lines each define the marginal edges of the corner post panels 2,3,4,5 and 
6 and and a glue lap 1. A corner post is fabricated from the blanks of 
FIGS. 1 and 1A by first folding panel 6 about score line 11 to position 
panel 6 in face-to-face contact with panel 5. The two panels 5 and 6 can 
be adhered to one another but in the preferred embodiment they are simply 
held together by appropriate machinery well known in the trade. The next 
step in fabricating the corner post consists of applying a strip of 
adhesive 17 to the panel 6 in a predetermined location to align with glue 
lap 1. Subsequently, the group of panels 1,2,3 are folded over about fold 
line 9, and glue lap 1 is adhered to panel 6 to produce the collapsed 
corner post 21 as shown in FIG. 2. At this stage, the fabrication of the 
basic corner post is complete and it can be advantageously shipped to the 
user in the flattened condition for storage until used. Later, the corner 
post 21 is erected to its useable condition as shown in FIG. 3 by simply 
urging the two folds at 9 and 11 towards one another. When erected the 
corner post assumes a cross-sectional configuration substantially in the 
form of an integral rectangular tube (panels 2,3,4) and attached leg 
(panels 5,6). 
The various panels of the blank 20 are preferably of unequal width in order 
that the blank can be folded into its flattened configuration for shipment 
and still be erected into a useable condition. As an example, a corner 
post three feet in length with an attached leg about 5 inches in width 
could be formed from a 3/16 inch thick blank measuring 36 inches by 19 
15/16 inches. In this example, panel 6 would be about 4 13/16 inches 
wide, panel 5 about 5 inches wide, panel 4 and 3 3/8 inches wide, panel 3 
about 2 inches wide, and panel 2 about 3 inches wide and glue lap 1 about 
1 3/4 inches wide. In designing the corner post 21 for a particular 
application the width of panel 5 is first determined. With the design 
width of panel 5 established panel 6 cannot have a maximum width any 
greater than the width of panel 5 less the thickness of the blank 
material. Meanwhile, the minimum width of panel 6 cannot be less than the 
width of panel 5 minus the width of panel 3. Similarly, the maximum 
dimension of glue lap 1 cannot be greater than the width of panel 5 minus 
the width of panel 3, and the minimum width of glue lap 1 cannot be too 
small or a good bond between glue lap 1 and panel 6 will not be achieved. 
Panels 2,3, and 4 which form the integral rectangular tube of the corner 
post, are sized as follows: the width of panel 4 is equal to the width of 
panel 2 plus the thickness of the blank material plus the outside gain 
produced by the fold 9 between panels 3 and 4. In addition, the width of 
panels 1,2 and 3 cannot exceed the width of panels 4 and 5 or the formed 
structure is difficult to collapse. 
The blank is preferably die cut but other methods of manufacture could be 
used depending upon the desired configuration and ultimate use of the 
corner post. Where one or more portions of the tubular part of the corner 
post are to be collapsed, the cut lines 12 and 13 are applied to the 
panels 2,3 of the blank in a die cutting operation. The purpose of the 
collapsed sections of the corner post are to provide void areas in front 
of control knobs, handles or other projections on the packaged products to 
aid in collapsing portions of the corner post tube, and depending upon the 
thickness of the blank material, it is advisable to add double scores 9 
and 16 in the regions to be collapsed between panels 3 and 4. The double 
scores are preferably spaced apart an amount that is substantially equal 
to the thickness of the blank material. Thus, as applied to the blank the 
scores 9 and 16 do not appreciably affect the folding sequence for forming 
the corner post and for flattening the post structure for shipment and 
storage. However, when the corner post tube is manipulated in order to 
collapse selected portions, the paired fold lines 9,16 in the collapsed 
region assure a smooth and efficient operation. 
The corner posts of the present invention can be used several different 
ways. In some instances, the packaged product 23 is first placed in its 
shipping container 22 prior to insertion of the corner posts 21. FIG. 6 
illustrates schematically a typical product 13 in a container 22 with 
corner posts 21 at each corner. In the instance where the corner posts 21 
are inserted in the container after the packaged product, the posts must 
be inserted in such a manner that the uncollapsed portions of the tube do 
not have to clear any protruding parts of the packaged product. In other 
instances, where the product has handles or other projections that are 
spaced apart or located near the midpoint of the product, the corner posts 
21 can be erected, portions thereof selectively collapsed, and then the 
corner posts can be fitted to the product and strapped in place. Later, 
the shipping container can be wrapped around the protected product or the 
product can otherwise be placed in its container. 
It will be noted by those skilled in the art that the specification and 
drawing illustrate at least two embodiments of the present invention. 
Further, by practicing the disclosure set forth herein one could readily 
produce a corner post having a tubular part of any desired cross-sectional 
shape commensurate with the intended use. Moreover, where the packaged 
article had a plurality of handles, knobs or other projections, parts of 
the tubular portion could be made selectively collapsible by applying 
several spaced cuts in panels 2 and 3, to accommodate the product without 
imparing the function of the corner post. Other details of construction 
could also be altered without departing from the principles of the 
invention as defined in the appended claims.