Collapsible shipping container

A collapsible shipping container comprising a base portion, three walls which are hinged to the base at their respective lower edges, a fourth wall which assembles to the base by sliding into a channel, four identical corner posts having a pair of channels for sliding on to the vertical edges of the four sides, and a top lid. The hinges on the side walls allow the three hinged side panels to fold over onto each other in a tightly layered configuration. The hinges do not carry a load which allows the containers to be stacked. The corner posts have locking pins which fit into holes on the tops of the walls to firmly lock the walls together. Skids are provided on the bottom portion to allow the container to be picked up and moved by forklifts. The top lid holds the corner posts and completely encloses the collapsed container. Alternatively, the container may accept snap-in casters on the bottom.

BACKGROUND OF THE INVENTION 
The present invention relates generally to the field of containers for the 
transportation of general cargo, and in particular, to containers which 
may be collapsed into a compact configuration for storage or return to a 
point of origin. 
Shipping containers in which the walls fold to form a collapsed 
configuration are well known. Such containers have the advantages of 
allowing a compact folded configuration which facilitates storage and 
shipment. Quite commonly, a manufacturer ships parts to a distant point of 
assembly from which empty containers must be returned to the manufacturer. 
It is of course highly inefficient to ship empty containers; therefore, 
many attempts have been made to develop a collapsible container which 
demonstrates efficiency, durability, ease of use, minimum collapsed 
configuration, flexibility of use, and strength. 
One of the problems associated with the use of collapsible containers is 
ensuring that the unfolded configuration has the requisite degree of 
strength. Various patents disclose the use of corner posts to tie together 
the side panels in a collapsible shipping container. U.S. Pat. No. 
3,266,656 issued to Kridle on Aug. 16, 1966 for "Demountable Shipping 
Case" discloses a collapsible shipping container with a base having a 
flange around its outside edge, four rectangular side panels, four corner 
posts each having a pair of channels to receive the vertical edges of the 
side panels, and a cover. The side panels of Kridle, however, are not 
hinged and the corner posts do not disclose the use of pins to tie the 
side panels together. 
U.S. Pat. No. 4,174,045 issued to Heller on Nov. 13, 1979 for "Loading 
Platform" does, however, disclose corner posts which have a plate at the 
top with a slot to receive extensions formed in the top edges of the side 
panels. 
Another shipping container disclosing corner connectors is U.S. Pat. No. 
5,236,099 issued to Fties et al. on Aug. 17, 1993 for "Plastic Knock Down 
Bin-Pallet for Loading, Transporting and Storing Fruits, Vegetables, Fish 
or Other Foods." Fties et al. disclose corner connectors which have a pair 
of channels for interlocking with the side panels of a collapsible 
container. 
U.S. Pat. No. 3,401,814 issued to Chiswell on Sep. 17, 1968 for 
"Collapsible Shipping Container" discloses a container having a base and 
four corner posts, four detachable side panels and a roof section. The 
same type of corner posts are disclosed in U.S. Pat. No. 4,050,604 issued 
to Flanders on Sep. 27, 1977 for "Disassembleable, Reusable Container." In 
both of these patents, the corner posts are simple angle pieces which do 
not provide channels to receive the edges of the side panels. 
Many designs of collapsible shipping containers employ the concept of 
folding the side walls about hinges. Some of the problems associated with 
the use of hinges include the durability of the container and its 
strength, both in the collapsed and the unfolded configuration. One 
particular problem is to avoid the loading of the hinges which can promote 
premature failure in the fully unfolded configuration and which may limit 
the ability of the folded or collapsed configuration to be stacked for 
efficient shipment. The following are examples of patents for collapsible 
shipping containers in which some or all of the walls are hinged to the 
bottom portion. U.S. Pat. No. 4,858,779 issued to Zimmerlund on Aug. 22, 
1989 for "Container" is a somewhat complicated arrangement for folding the 
sides together to form a compact package. Zimmerlund does, however, 
recognize the problem of arranging the hinges so that the panels bear on 
one another and not on the hinge structure itself. 
U.S. Pat. No. 5,253,763 issued to Kirkley on Oct. 19, 1993 for "Collapsible 
Container" discloses a container in which two of the side walls are hinged 
and two of the side walls are removable for stacking onto the folded 
hinged sides. Kirkly does not disclose the use of corner posts and the 
appropriate stacked configuration is obtained by folding the side panels 
about central hinges. 
A final example of a shipping container in which the sides are hinged is 
U.S. Pat. No. 3,040,925 issued to Mills on Jun. 26, 1962 for "General 
Cargo Shipping Container." Mills recognizes the desirability of being able 
to open a side of a shipping container for easy loading and unloading. 
SUMMARY OF THE INVENTION 
The collapsible shipping container of the present invention comprises a 
base portion, three walls which are hinged to the base at their respective 
lower edges, a fourth wall which assembles to the base by sliding into a 
channel, four identical corner posts which have a pair of channels for 
sliding on to the vertical edges of the four sides, and a top lid. There 
are a number of significant features to various embodiments of the 
invention: (1) there are no loose parts or connectors required to assemble 
the container other than the parts mentioned above, (2) the hinges on the 
side walls are mounted on short "stub walls" raised above the base to 
allow the three hinged side panels to fold over onto each other in a 
tightly layered configuration, (3) the hinges on the side panels are 
designed so that they do not carry a load which allows the containers to 
be stacked, one on top of another, (4) the corner posts are provided with 
locking pins which fit into holes on the tops of the side panels to firmly 
lock the side panels together, and (5) skids are provided on the bottom 
portion to allow the container to be picked up and moved by forklifts. 
There are various other features to other embodiments of the invention; 
for example, the fully collapsed configuration of the container and the 
manner in which the top lid holds the corner posts and completely encloses 
the remaining portion of the collapsed container. Other features include 
the ability to stack the folded containers, sizing of the fully unfolded 
container to fit in semi-trailers or modular shipping containers, and the 
ability to accept snap-in casters on the bottom. 
To overcome the limitations and disadvantages of the prior art, it is an 
object of the present invention to provide for a collapsible shipping 
container which collapses to a minimum configuration which is efficient to 
store and ship. 
It is a further object of the present invention to provide for a 
collapsible shipping container which exhibits a high degree of strength 
and durability in both the collapsed and the fully unfolded configuration. 
It is an additional object of the present invention to provide for a 
collapsible shipping container which minimizes the number of parts 
required to assemble the shipping container in its fully unfolded 
configuration and provides means to store parts in such a way as to avoid 
or minimize the loss of loose parts and to avoid the need for tools to 
assemble and disassemble the container. 
It is a still further object of the present invention to provide for a 
collapsible shipping container which is so oriented and configured as to 
promote a natural and obvious mechanism for folding and unfolding the 
shipping container, thereby maximizing efficiency in using the invention. 
Further objects and advantages of the present invention will become 
apparent from the detailed description of the preferred embodiments 
considered in conjunction with the appended drawings as described 
following:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference may now be made to the drawings to describe the preferred 
embodiments. FIGS. 1, 2 and 3 illustrate the exterior appearance of the 
collapsible shipping container in the fully unfolded configuration. The 
collapsible shipping container comprises a base portion 10, a front wall 
11, a left side wall 12, a right side wall 13, a back wall 14, a top lid 
15, and four identical corner posts 16. 
The base portion 10 additionally comprises a plurality of skids 17 which 
allow the collapsible shipping container to be moved by forklift since the 
spaces under the collapsible shipping container defined by the skids 17 
allow access by forklift arms. In an alternative embodiment the 
collapsible shipping container may be provided with means to accept 
snap-in casters (not shown) of a type well known in the art so that the 
collapsible shipping container may be easily moved by rolling. 
Assembly of the collapsible shipping container from the fully collapsed 
configuration into the fully unloaded configuration as shown in FIGS. 1 
through 3 will be described more fully hereinafter. However, it may be 
conveniently noted at this point that the final step of assembly of the 
collapsible shipping container into the fully unfolded configuration 
involves placing the top lid 15 into position on top of and surrounding 
the tops of the fully unfolded and assembled walls 11, 12, 13 and 14. In 
order to secure the top lid 15 in position, a pair of latches 18 are 
provided. FIG. 2 shows one of the two latches 18 in relation to the right 
side wall 13. Not illustrated is the other one of the pair of latches 18 
in relation to the top lid 15 and the left side wall 12. 
In order to facilitate moving the collapsible shipping container in either 
the collapsed configuration or the fully unfolded configuration, as well 
as assisting in the operation of unfolding the collapsible shipping 
container, the top lid 15 is provided with a pair of handles 19. The 
handles 19 are sized so as not to interfere with stacking of the 
collapsible shipping container as will be described more fully 
hereinafter. 
As an additional aid in assembling the collapsible shipping container or 
moving the fully unfolded collapsible shipping container, the front wall 
11 is provided with a collapsible handle 20. The collapsible handle 20 
provides a convenient means for grasping and maneuvering the collapsible 
shipping container in the fully unfolded configuration. The collapsible 
handle 20 also assists in the assembly of the front wall 11 into the fully 
unfolded configuration as described more fully hereinafter. The 
collapsible handle 20 assumes a flattened shape so as not to interfere 
with the folding of the right side wall 13 onto the front wall 11 when the 
collapsible shipping container is folded. 
In addition to the features described above, the top lid 15 includes a pair 
of skid channels 21 which act as receptacles to receive the skids 17 so as 
to ensure the secure stacking of either the collapsed configuration of the 
collapsible shipping container or the fully unfolded configuration. 
Further, the base portion 10 also includes a floor 23 and a front wall 
channel 22 disposed on the upper front edge of the floor 23 to receive the 
bottom edge of the front wall 11. The preferred construction of the floor 
23 as well as the functioning of the front wall channel 22 will be 
described more fully below. 
The fully collapsed configuration of the collapsible shipping container is 
shown in FIG. 12. As may be seen from FIG. 6, the top lid 15, in addition 
to the features already described, is essentially a box with a top 30, 
four sides 31 depending downward therefrom and an open bottom. To proceed 
from the fully unfolded configuration shown in FIGS. 1 through 3 to the 
fully collapsed configuration shown in FIG. 12, the following steps occur. 
The latches 18 are disengaged and the top lid 15 is lifted off. The handles 
19 may assist in this process. The four corner posts 16 may be removed by 
sliding the corner posts 16 upward. The front wall 11 is at this point 
held in position only by its lower edge inserted into the front wall 
channel 22. The collapsible handle 20 may be used to assist in lifting the 
front wall 11 from the channel 22. The front wall 11 may then be placed on 
to the floor 23 of the base portion 10. The front wall 11 is sized to fit 
within the area bounded by the front wall channel 22, the left wall 12, 
the right wall 13 and the back wall 14. This sequence of folding has the 
advantage of allowing the stowage of the front wall 11 immediately upon 
its disassembly from the container. Likewise upon unfolding the walls the 
front wall 11 is available for assembly without the need to remove it and 
place it to one side while other assembly is completed. 
Next, the right wall 13 is folded over onto the front wall 11 as shown in 
FIG. 6. It should be noted that until either the left wall 12 or the right 
wall 13 are ready to be folded, the respective corner posts 16 may be left 
in position between the back wall 14 and the respective left wall 12 or 
right wall 13 until folding is commenced. 
Proceeding with FIGS. 4 and 5, the remainder of the folding may be 
described. FIG. 5 illustrates the stage in the folding process at which 
time the front wall 11 and the right wall 13 are fully collapsed. From 
this point any remaining corner posts 16 may be removed and the back wall 
14 folded onto the right wall 13 as shown in FIG. 4. The left wall 12 may 
then be folded onto the back wall 14. 
The stowing of the corner posts 16 may now be described with reference to 
FIG. 11. FIG. 11 shows the top lid 15 in a perspective view from the 
underside. As noted above, the top lid 15 is a box-like structure 
comprising a top 30 and four sides 31. The strength of the top lid 15 is 
enhanced by transverse structural members 40. The transverse structural 
members 40 are disposed on the underside of the top 30 between one pair of 
opposite sidewalls 31. The transverse structural members 40 are basically 
box beams, and due to their spacing, define a space between adjacent pairs 
of the transverse structural members 40, which is employed to receive the 
disassembled corner posts 16. As shown in FIG. 11, the disassembled corner 
posts 16 are held in position by a retaining arm 41 which is pivotally 
mounted to one transverse structural member 40 and received in a retaining 
bracket 42 located on an adjacent transverse structural member 40. 
After stowing the disassembled corner posts 16 into the top lid 15, the top 
lid 15 is placed over and on top of the fully collapsed base portion 10 
and walls 12, 13 and 14 in a telescopically sliding fashion which 
substantially surrounds the collapsed walls 11, 12, 13, and 14 with the 
box-like shape of the top lid 15. The result is the configuration shown in 
FIG. 12. The collapsible shipping container in the fully collapsed 
configuration shown in FIG. 12 may be easily stacked for efficient storage 
or shipment as shown in FIG. 13. FIG. 13 illustrates the manner in which 
the skids 17 are received in corresponding skid channels 21. 
Returning the collapsible shipping container to the fully unfolded 
configuration involves the reversal of the steps described above. The 
folding of the walls 12, 13 and 14 have been described generally above. 
The following describes the manner in which the walls 12, 13 and 14 are 
hinged to the base portion 10 so as to allow folding of the collapsible 
shipping container into a minimum configuration. The hinge mechanism of 
the present invention also assures that when fully unfolded the walls 12, 
13 and 14 carry any superimposed loads directly to the base portion 10 
without loading the hinges. Furthermore, the hinging mechanism of the 
present invention assures that when fully folded, any loads superimposed 
on the walls 12, 13 and 14 are carried directly to the base portion 10 
without loading the hinges. 
The hinge mechanism may be described with reference to FIGS. 7A through 7D. 
As noted above, the front wall 11 is assembled onto the base portion 10 by 
placing the lower edge of the front wall 11 into front wall channel 22. 
This arrangement is shown in a cross-sectional detail in FIG. 7D. It may 
be seen that any vertical load superimposed on the front wall 11 is passed 
directly through the front wall channel 22 to the floor 23 and thence to 
the skid 17. When unfolded, the same relationship holds with the walls 12, 
13 and 14 since the hinge is offset and allows the walls 12, 13, and 14 to 
bear directly on the "stub walls" to be described following. FIG. 7C 
illustrates the right side wall 13 in a sectional detail. In FIG. 7C the 
right side wall 13 is unfolded. The right side wall 13 bears directly onto 
a right side stub wall 50 which is attached to and bears on the floor 23 
and thence to the skid 17. The right side stub wall 50 is hingedly 
attached to the right side wall 13 by a right side hinge 60. The right 
side stub wall 50 has a height equal to the thickness of the front wall 
11. When the disassembled front wall 11 is placed in position on the floor 
23, the right side wall 13 may be folded about the right side hinge 60 
onto the front wall 11 so that any load superimposed on the right side 
wall 13 bears uniformly on the front wall 11 without loading the right 
side hinge 60. 
In a precisely analogous fashion as shown in FIG. 7b, the back wall 14 is 
hingedly attached through a back wall hinge 61 to a back stub wall 51 
which is affixed to the floor 23. Any load superimposed on the back wall 
14 in the unfolded configuration bears directly onto the back stub wall 51 
and thence to the floor 23 and the skid 17. The back stub wall 51 has a 
height equal to the combined thicknesses of the front wall 11 and right 
side wall 13 so that when folded over onto the right side wall 13, any 
load superimposed on the back wall 14 in the folded configuration bears 
uniformly onto the right side wall 13 and thence through the front wall 11 
to the floor 23 and the skid 17 without bearing on the back wall hinge 61. 
Continuing in analogous fashion to FIG. 7A, the left side wall 12 is 
hingedly attached to the left side stub wall 52 through the left side wall 
hinge 62. The left side stub wall 52 has a height equal to the combined 
thicknesses of the front wall 11, the right side wall 13 and the back wall 
14. In the unfolded configuration, any load superimposed on the left side 
wall 12 bears directly on the left side stub wall 52 and thence through 
the floor 23 to the skid 17. In the folded configuration, the left side 
wall 12 is folded about the left side wall hinge 62 onto the back wall 14 
and thence through the right side wall 13, front wall 11, floor 23 and 
skid 17 without loading the left side wall hinge 62. In the preferred 
embodiment, the thicknesses of the walls 11, 12, 13, and 14 are 
advantageously uniform and identical. In other embodiments, the 
thicknesses of the walls 11, 12, 13, and 14 may not be identical, but may 
be accomodated within the scope of the present invention by adjusting the 
height of the stub walls accordingly. 
While this folding arrangement has been described with the particular 
sequence of folding the right side wall 13, then the back wall 14, and 
finally the left side wall 12, the scope of the present invention is not 
so limited and is intended to encompass other sequences of folding. 
When the collapsible shipping container of the present invention is 
unfolded into the fully unfolded configuration, a primary consideration 
becomes the strength of the fully unfolded configuration. The corner post 
16 provides the requisite strength in two ways as illustrated in FIGS. 8 
and 9. For purposes of illustration, FIG. 8 will be taken to illustrate 
the manner in which a corner post 16 joins the back wall 14 and right wall 
13; however, the same principle applies to the use of the corner post 16 
to join any adjacent pair of walls. The corner post 16 comprises a pair of 
vertical channels 70. The vertical channels 70 are oriented at right 
angles so as to receive the vertical edges of adjacent walls (in the 
particular case illustrated in FIG. 8, back wall 14 and right wall 13). 
The corner post 16 is assembled to a pair of adjacent walls by vertically 
sliding the channel 70 over the respective edges of the adjacent side 
walls. This ensures that the adjacent side walls are firmly interlocked 
along their entire height. 
As shown in FIG. 9, however, an additional assurance of a strong and rigid 
container can be obtained by firmly interlocking adjacent wall panels at 
their respective top edges. For purposes of illustration, FIG. 9 
illustrates the manner in which a corner post 16 interlocks the left wall 
12 with the back wall 14. This is merely illustrative, however, and 
applies to the method of interlocking any adjacent pair of walls. As shown 
in FIG. 9, the corner post 16 is provided with a gusset 71 horizontally 
spanning the top of the corner post 16. The gusset 71 is provided with a 
pair of downward pointing pins 72. Each adjacent wall (12, 14 in this 
illustration) is provided with an opening 73 along its respective upper 
edge for receiving the downward pointing pins 72. The corner posts 16 are 
therefore employed to lock a pair of adjacent walls into position both by 
the sliding engagement of the channel 70 and by locking the pins 72 into 
the respective openings 73. By these two means, a thoroughly rigid and 
fully interlocked structure is achieved. 
Additional structural integrity is achieved by placing the top lid 15 onto 
the assembled structure so that the side walls 31 completely encompass the 
tops of the assembled walls and corner posts. As noted above, the top lid 
15 may then be locked into position by engagement of the latches 18. 
Additional structural integrity is achieved by the method of constructing 
the floor 23. As illustrated in FIG. 10, the floor 23 is assembled from a 
plurality of interlocking extrusions 75. This technique allows for ease in 
manufacture as well as providing great structural strength in an area of 
the collapsible shipping container which is likely to carry the heaviest 
load. 
As shown in elevation cross section in FIG. 10, each extrusion 75 is 
provided with a recess 90 along one edge of the extrusion 75. The recess 
90 has a convexly radiused upper rim 91 and a concavely radiused lower rim 
92. Further each extrusion 75 is provided with a tongue 93 along the 
opposite edge of the extrusion 75. The tongue 93 has a concavely radiused 
upper surface 94 and a convexly radiused lower surface 95. The elevation 
cross section of the recess 90 as shown in FIG. 10 is therefor 
complementary to the elevation cross section of the tongue 93. Assembly of 
a first extrusion 75 to a second extrusion 75 is accomplished by placing 
the second extrusion at angle to the first extrusion and fitting the 
tongue 93 of the second extrusion 75 into the recess 90 of the first 
extrusion. Tilting the second extrusion downward slides the tongue 93 into 
the recess 90 until the tongue 93 is fully seated in the recess 90 and the 
two extrusions 75 are firmly locked together as shown in FIG. 10. 
In order to use the collapsible shipping container for shipping 
merchandise, the container in the fully collapsed configuration as shown 
in FIG. 12 is assembled following the steps outlined above. The top lid 15 
is removed and the corner posts 16 are removed from the top lid 15. The 
left side wall 12 is unfolded as shown in FIG. 4 and the back wall 14 is 
unfolded as shown in FIG. 5. A corner post 16 is then placed in position 
engaging the left side wall 12 and the back wall 14. Next, the right side 
wall 13 is unfolded as shown in FIG. 6. An additional corner post 16 is 
used to assemble the right side wall 13 to the back wall 14. The front 
wall 11 is then removed and assembled into position in the channel 22. 
Alternatively, the front wall 11 may be removed and placed to one side so 
that the collapsible shipping container may be easily loaded through the 
gap left by the front wall 11. Once the collapsible shipping container is 
fully loaded, the container assembly may be completed by placing the front 
wall 11 in position in the front wall channel 22. The front wall 11 is 
then fixed into position by the assembly of a corner post between the 
front wall 11 and the left side wall 12 and between the front wall 11 and 
the right side wall 13. The final step to complete assembly of the fully 
loaded collapsible shipping container is to place the top lid 15 in 
position as shown in FIGS. 1 through 3. 
The fully assembled and loaded collapsible shipping container may be 
stacked using the skid 17 and skid channels 21 in precisely the same 
fashion as shown in FIG. 13 for the fully collapsed configuration. The 
collapsible shipping container may advantageously be sized so as to fit 
without wasted space in intermodular shipping containers which are of a 
standard size. A useful modular size would be 4 feet by 4 feet by 4 feet. 
However, the present invention is not limited to precisely this size and 
may advantageously be constructed in varying sizes. 
An advantage of the present invention is that it may be assembled without 
the use of bolts or similar fastening devices. All loose parts are 
minimized and easily stored, thereby minimizing the risk of loss. 
Furthermore, the entire assembly and disassembly process may be undertaken 
manually and without the need for any type of tools. 
The present invention has been described with reference to certain 
preferred and alternative embodiments which are intended to be exemplary 
only and not limiting to the full scope of the present invention as set 
forth in the appended claims.