CA1268431A - Heavy-duty shipping container for flowable bulk materials - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A heavy-auty shipping container for flowable bulk materials comprises an outer sleeve of multi-wall corrugated fibreboard extending vertically from a bottom edge to a top edge thereof and having a polygonal cross section made of plurality of sidewall panels. An inner sleeve which is substantally co-axial with the out sleeve has a cylindrical cross section and is also made of muiti-wall corrugated fibreboard. A multiplicity of false scores is formed on the inner surface of the inner sleeve upon its being bent into a cylindrical shape. The inner sleeve contacts the outer sleeve along the center of each side panel. The upper edge of the inner sleeve is initially positioned above the upper edge of the outer sleeve by a thickness which is less than the thickness of a bottom support pad positioned under the lower edge of the inner sleeve. With one container stacked on another, the inner sleeve of the lower container is pushed downwardly to deform the outer periphery of the bottom pad and bring the upper edges of the inner and outer sleeve into coplaner positions in their post-loading condition.
In this way, both the inner and outer sleeve contribute to the column strength of the container.

Description

~ ~ .

1;~6843~

HEAVY-DUTY SHIPPING CONTAINER
FOR FLO~ABLE BULK MATERIALS

BACKGROUND OF THE INVENTION

This invention relates to shipping containers for flowable substances and, more particularly, to heavy-duty shipping containers for the bulk transport of flowable bulk materials, including liquids, dry powders or granular substances, semi-solid materials such as grease, pastes or :
adhesives and, as well, highly viscous fluids, in volumes 10 of at least fifty-five gallons and in quantities of weight greater than four hundred-fifty pounds.
~:Shipping containers used fo~ the transport of ~;flowable bulk materials must accommodate extraordinary weight, due to the high density of the contained materials and, at the same time, must be designed to withstand damage that can result from the nonuniform and sometimes cyclic stresses caused by the material shifting during the handling and transport of the container. Even a minor puncture or cFack can cause the total loss of the flowable . :
;`:
', ,~

~ - , . ..

~ ,. ~ , . ... ~ .
: ~ . . . . . .; : ., - . -; ~

material. Heavy-duty shipping containers containing bulk flowable materials exceed the limits of manual handling capability and are typically mounted on pallets and handled by mechanical means such as fork lifts and hand-lift trucks.
Various types of containers and container materials have been designed for the transport of flowable bulk materials. Single wall (double face) corrugated fibreboard boxes, for example, have been used as inexpen-sive, disposable containers for light-duty applications.
Sucb fibreboard containers, where necessary, are waxed or provided with a plastic liner bag. As the volume and weight of the contained material increases, however, the pressure of the material within the container causes bulging of the sides of the container. This makes the container difficult to stack with other similar contain-ers. Furthermore, the bulging of the sides of the container significantly reduces the inherently limited column strength of single wall containers making this type of container unsuitable for stacking or heavy-duty applica-tion.
The term fibreboard is a general term applied to paperboard utilized in container manufacture. Paperboard refers to a wide variety of materials most commonly ~ade from wood pulp or paper stock. Containerboard refers to the paperboard components -- liner and corrugating material -- from which corrugated fibreboard is manufact-ured. Thus, the term fibreboard, as used in the packaging industry and in tbe present specification and claims, is intended to refer to a structure of paperboard material composed of various combined layers of containerboard in sheet and fluted form to add rigidity to the finished product. Fibreboard is generally more rigid than other types of paperboard, allowing it to be fabricated into ~: .

:
., -. ,~ :
. , . . ; - -~ .
,, :: . ~

- . ~, : : - : , ~: , - , , , . , ., -~L26843~

larger sized boxes that hold their shape and have substantial weight bearing capability.
Double or triple wall corrugated fibreboard, when made into shipping containers, provides many distinct 5 advantages for the packaging and transport of heavy loads. Double wall corrugated fibreboard comprises two corrugated sheets interposed between three flat facing or spaced liner sheets. In triple wall corrugated fibre-board, three corrugated sheets are interposed between four lO spaced facing or liner sheets. Triple wall corrugated fibreboard, in particular~ compares favorably with wood in rigidity and strength and, as well, in cost, and provides cushioning quality not found in wooden containers. In addition, triple wall corrugated fibreboard, relative to 15 other fibreboard materials, advantageously provides great column strength. The column strength of triple wall corrugated fibreboard containers permits stacking, one on top of the another, of containers containing heavy loads without excessive buckling or complete collapse of the 20 vertical walls. Triple wall corrugated fi~reboard also has great resistance against tearing.
Fibreboard shipping containers employing an outer multi-sided tubular member and a simularly configured inner reinforcement to strengthen the overall container 25 have been disclosed. See~ for example, U.S. Patents 3,159,326, 3,261,533 3,873,917, 3,937,392, 4,013,16~ and 4,41R,861.
In order to form multi-sided fibreboard tubes, it is necessary to form major score lines in the fibreboard to allow bending of the fibreboard along the edges of each panel of the container which is formed. However~ scoring ; adversely affects the container since the lateral stabil-ity of the container significantly decreases as the number of major score lines is increased. The major scoring of :

' -, -. .
~;
- -;:
. .

~431 the container typically permits the container, when empty, to be shipped in a ~nocked down, flat condition.
Circular cylindrical-shaped containers have long been regarded as the most efficient shape to use in containing liquids or dry flowable products. Paperboard designs utilizing circular cylindrical type containers, however, have been restricted to small capacity cylind-rical shapes typlified by the 55 gallon capacity spiral wound fibre drum. Producing larger containers of this type has proven impractical, on a commercial basis, due to a number of reasons including excessive ma~erial and fabrication costs and the unavailability of fabricating equipment. Moreover, the fibre drums are rigid and cannot be folded into a flattened state when empty. Since existing technology requires that these fibre drums ~e pre-erected at a central location and then shipped to and stored empty in an erected or pre-formed condition at user locations, the utilization of cylindrical fibre drums also presents handling, shipping, and storing difficulties.
Most importantly, the structural per~ormance and handling requirements of a fibre drum, as capacity climbs to the llO gallon to 380 gallon range, have exceeded the indus-try's ability to produce a readily available commercial product. Utilization of higher-strength reinforced plastic or metal drums has not provided a satisfactory alternative as such materials are typically more expen-sive, do not increase utilization of cubic storage space, when empty, and present a variety of disposal problems.
Thus, despite the efficiencies of circular cylindrical containment, corrugated ~ibreboard has not been generally used as a circular cylindrical container material. corrugated fibreboard, particularly in the heavier grades of multi-wall fibreboard capable of containing and supporting the weights and hydrostatic pressures produced by 110 to 380 gallons of contained ;' .

,, ~ -.

. .
..
- ::: ' liquid, or an equal volume and weight of flowable solids, does not lend itself to being fabricated into circular cylindrical shapes without substantial loss of key performance features of corrugated fibreboard, that is, top to bottom compression strength and lateral stability.

SUMMARY OF THE INVENTI~N

The invention is directed to a heavy-duty shipping container for bulk materials comprising an inner tubular sleeve of a multi-wall corrugated fibreboard of substantially circular cross section, adapted to contain a flowable bulk material, and an outer sleeve of polygonal cross section assembled about the inner sleeve for its full length, the outer member also being constructed of a multi-wall corrugated fibreboard. The inner circumferen-tial facing of the inner sleeve is formed with a pluralityof false scores extending lengthwise, i.e. substantially parallel to the length of the inner sleeve or parallel to the flutes or corrugations thereof.
The outer sleeve is preferably constructed of triple wall corrugated fibreboard and is preferably ; octagonal in cross section.
The inner sleeve is a corrugated fiberboard sleeve in the form of a right circular cylinder formed of a multi-wall corrugated fibreboard such as double wall or, ; 25 preferably, a triple wall corrugated fibreboard which has been subjected to a bending process to form the false scores randomly at intervals of one to six inches.
Preferably, the outer sleeve of the container is provided with bottom end flaps of single-wall corrugated fibreboard and is provided with a removable upper end cap formed from folded corrugated fibreboard.

... .

' ~` ' ; '' ,~; ~` `'` ' ~ ,, ~ : ', ~ :

~L26843~L

When formed, shipping containers made in accord-ance with the invention are designed to contain flowable materials in volumes of at least 55 gallons and weights exceeding four hundred-fifty pounds.
Shipping containers of the invention, in compar-ison to steel or fibre drums presently in use, per unit of volume are less costly on a material and fabrication basis. The shipping containers of the invention provide increased utilization of cubic storage space when the containers are being shipped or stored empty in that the - inventive shipping containers can be folded flat when not is use. Moreover, since tbe materials employed have recycle salvage value and, as well, are biodegradable, post-use disposal does not present problems associated with plastic and metallic containers.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding parts throughout the same, Figure 1 is a schematic perspective view of a shipping container, partly broken away, formed in accord-ance with the inqention;
Figure 2 is a top view of a shipping container, with the top cap removed, formed in accordance with an embodiment of the invention;
Figure 3 is an enlarged view of the encircled detail of Fig. 2;
Figure 4 is a section of a portion of a side and the bottom of the shipping container of Fig. l;
Figure 5 is a top plan view illustrating a blank, prior to false scoring, from which an inner sleeve of the shipping container may be formed;

' ' - ' :: ., :. '::. . . .. ..

: ~,, ,. : -:~, . - :
. .

~.,6~431 Figure 6 is a top plan view of a blank from which an outer sleeve of the shipping containers may be formed;
Figure 7 is a sectional view taken along line 7-7 of Fig. 6;
5- Figure 8 a perspective view showing on end flaps of and outer sleeve of the shipping containers; and . Figure 9 is an exploded schematic view, in perspective, illustrating a shipping assembly embodying the invention.

"

.~ .
~, . : .. ' ,' . ....... -~Z6~ 3~

DETAILED DESCRIPTION

The shipping container 10, as disclosed herein, is constructed with a right circular inner cylindrical sleeve 12 of a multi-wall corrugated fibreboard substant-ially coaxially received within an outer sleeve 14 of amulti-wall corrugated fibreboard which has a polygonal cross section as best shown in Figures 1, 2 and 3.
The inner sleeve 12 is a multi-wall corrugated fibreboard which may consist of a single wall or double wall corrugated fibreboard for certain applications. In accordance with the preferred embodiments of the inven-tion, the inner sleeve 12 is preferably composed of triple wall corrugated fibre~oard as is illustrated by Figure 4.
Corrugated fibreboard, particularly heavy grades such as double and triple wall corrugated fibreboard, when used for inner sleeve construction, dramatically increases the stacking strength of the overall container as compared to a solid fibre and single wall inner sleeves.
The inner sleeve 12, in the preferred embodiment, is formed from a flat sheet 11 of triple wall corrugated fibre~oard. The flat sheet 11, as shown in Figure 5, is first formed with two major score lines 13, 17, provided preferably at diametrically opposite locations on the assembled inner sleeve 12, to allow the inner sleeve to be shipped, when empty, in a knocked down condition, with a uniform folded slope. The flat sheet 11 is circularly shaped in a ~ending apparatus, such as a sheet metal roller or-a modified four bar slitter, by subjecting the corrugated sheet to a prebreaking process. The prebreak-ing process comprises passing the corrugated sheet througha curved path having a radius of curvature which causes the random formation of multiple scores 75, so-called false scores, running in the direction of the corrugations, on the smaller radius of the curved sheet.

, . - ~: ,. . . .

: . . ~ . , , . :

~L26~
g The randomly spaced false scores 75, which in the case of a triple wall corrugated fibreboard occur variously, approximately from one to six inches apart, help facili-tate the formation of a nearly perf~ct cylindrical shape of the inner sleeve 12, when the inner sleeve is placed within the outer polygonal sleeve, and filled with a liquid or flowable solid substance. Besides providing these random scores, the pre~reaking process also stretches the outer facing of the corrugated fibreboard sheet, and compresses the inner facing to the extent that when assembled into a sleeve, and secured by a glue joint, the sleeve, although it can be folded flat, maintains a circular cylindrical shape when erected. The end portions of the sheet, which comprises the circular inner sleeve, are overlapped and adhesively combined in a lap ~oint.
The outer circumferential facing of the inner sleeve is not creased or scored but remains smooth.
The randomly-spaced false scores 75 of the corrugated fibreboard sheet, when assembled into a sleeve configuration, extend generally parallel to the longi-tudinal axis of inner sleeve 12. As used herein, it should be understood that the terminology ~false scores-does not comprise score lines of the type which are formed with a s~oring tool but are the type of scores known in the fibreboard industry as ~false scores" whicb result from the application of prebreaking stress to sheetstock materials. As best shown in the enlarged detail view provided in Figure 3, the false scores only crease the innermost (on the small diameter side of the sleeve) facing of the inner sleeve 12 of triple wall fibreboard.
In comparison, the mechanical scores 13, 17 formed to allow folding of the inner sleeve blank crease the innermost facing and, as well, the intermediate facings and flutes of the triple wall fibreboard comprising the inner sleeve 12. It is critical that the described false ....

., : . : , scores be used to obtain the circl~lar configuration of the inner sleeve as, for example, use of a multiplicity of numerous mechanical score lines would debilitate the strength of the inner sleeve.
outer sleeve 14, in accordance with a preferred embodiment of the invention, comprises a tubular member having an octagonal cross section The outer sleeve 1~ is formed from a substantially rectangular sheet 16 of corrugated fibreboard, or equivalent, shown in Figure 6 The rectangular sheet 16 is die cut and scored for folding, by techniques well understood in the art, and includes a plurality of substantially rectangular wall panels 18, 20, 22, 24, 26, 28, 30 and 32, foldably con-nected to each other by lateral score lines 34, 36, 38, 40, 42, 44, 46 and a sealing flange 48 foldably connected to wall panel 32 via a lateral score line 50. End flaps 52, 54, 56, 58, 60, 62, 64, 66 are formed at one of the opposite edges of the respective wall panels and are foldable along score lines 51, 53, 55~ 57, 59, 61, 63, 65 20 which are formed on the end flap approximately one-eigth inch from the bottom edge 68 of the wall panels. The wall panels are preferably formed from triple wall corrugated fibreboard which, as shown in Figure 7, include three corrugated sheets 70, 72, 7~. The ridges of the corru-25 gated sheets are adhesively secured to liner sheets 76, 78, 80 and ~2. The end flaps are preferably formed of single wall corrugated fibreboard, as shown in Fig~ 8.
which is integral to the triple wall side wall panels.
The end panels may be formed on a triple wall combiner 30 machine as part of the combiner process in a manner well-known to those skilled in the corrugated fibreboard container industry.
The rectangular sheet 16 is bent along the lateral fold lines into the form of an octagon, when 35 viewed in cross section. The sealing flange 48 overlaps .

.

. .
.. ... , ~ .

~L2~3~

the exposed face of liner 76 and is adhesively secured thereto, in a known manner, to form outer sleeve 14. The end flaps are then sequentially folded inwardly of the outer sleeve 14 so that adjacent flaps overlie each other. The use of end flaps adds to the structural integ-rity of the container. The end flaps can be omitted and a lower end cap, similar to the upper end cap, employed with less favorable results. Alternatively, both a bottom end cap and bottom end flaps can be utilized.
The inner sleeve 12 is then inserted into the outer sleeve 14. The outer sleeve 14 is sized such that the wall of the inner sleeve 12 touches at approximately the mid-point of each of the walls of the outer sleeve 14 as typically shown at lS. Gaps 19 are formed between the inner sleeve 12 and the corners of the outer sleeve 14, the corners being defined by the lateral score lines between the wall panels of the outer sleeve 14.
Although the outer sleeve 14 is shown as octagon-al in cross section, it will be appreciated that any poly-gonal cross section may be utilized.
The container 10 is preferably closed at its topby a removable end cap ~0, which has a cross section similar to that of the outer sleeve and, thus, in the illustrated embodiment has an octagonal configuration.
25 End cap 90 has a downwardly extending peripherial side `
flanges ~2 which extend outside and are engageable with the ends of the outer sleeve below the upper edge of the outer sleeve 14. The end cap 90 is not a load bearing member and, therefore, may be formed from single wall corrugated fibre~oard.
Figure 9 illustrates a shipping assembly in accordance with the invention. A separate pallet 96 of conventional construction is employed beneath the shipping container to facilitate movement of the containers by a fork lift or hand lift truck.

A bottom pad 98 is preferably inserted into the outer sleeve 14 and rests upon the infolded end ~laps 52, 54, 56, 58, 60, 62, 64. The bottom pad 98, in the illust-rated embodiment, has an octagonal-shaped cross section and is designed to be closely received within the outer sleeve 14. The peripheral edges of the bottom pad 98 bear against the side walls of the outer sleeve 14. The bottom pad 98 is preferably composed of triple wall corrugated fibreboard.
A plastic liner bag 100 is preferably provided - within the inner sleeve 12 to lleak-proof the container.
The liner bag 100 precludes the flow of the contained materials between the interstices that may exist in between the end flaps and at the bottom pad. A suitable liner bag 100 can be made from a flexible plastic film material, such as polyethylene extruded film or the like.
In certain applications, a compressible top pad 102 with a circular cross section is provided as a filler to fill any head space or void area th~t may exist or occur, for example, due to incomplete filling, settling, or contraction of the contained material, between the liner bag 100 and the end cap 90. The top pad 102 is particularly suited for applications in which a liquid is contained as it prevents, or at least helps to reduce, the harmful sloshing or surging of the liquid which tends to occur during transit motion. However, the compressibility of the top pad 102 still allows expansion of the liquid, thereby releasing some of the hydrostatic or hydraulic pressures which would otherwise be exerted against the sidewalls and bottom of the container. The top pad 102 is preferably composed of triple ~all corrugated fibreboard or polyether foam. The periphery of the top pad bears against the inner surface of the inner sleeve 12.
Steel strapping 84 is employed to hold the shipping containers to the pallet 96~ In order to avoid .

,, -.

~2~3~31 damage to the end cap 90, inverted U-shaped steel strap-ping braces 86 are mounted across the end cap 90 intermed-iate of both the upper surface and side flanges 92 of the end cap and the strapping 84. Each strapping brace 86 consists of a flattened central elongated plate and - depending legs designed to overlie the top surface and flanges 92, respectively, of the end cap. The braces 8~
are provided with a greater width than the strapping 8~ in order to more evenly distribute the strap forces over the shipping container. The surface of the strapping brace 86 is preferably beaded in order to inhibit slippage between the strapping and the brace. ~hen the strapping braces 86 are tightened down by the strapping 8g, the inner sleeve 12 is positively seated against the bottom pad 98 to further stablize the contained load. The end flaps are held in place by the weight of the contained materials pressing down on the bottom pad and, in conjuction with the pressure of the strapping, provide a s~rengthening or resistance t~ lateral deflection at the bottom of the outer sleeve 14, which is tbe area that is most vulnerable to buckling or deflection.
A bottom spou~ fitment 88, as is known in the bag`
industry, may be provided. Tha fitment 88 extends through cutouts formed in the outer sleeve and the inner sleeve.
The fitment 88 is connected to the liner bag to allow gravity evacuation of the material contained within the liner bag 100. The fitment extends through aper~ures formed through the walls of the inner and outer sleeves.
Actual containers, built in accordance with the inventiont have been subjected to drop tests, vibration tests and high humidity compression tests with markedly successful test results. The following examples are ! illustrative and explanatory of portion of the invention~
EXAMP~E I
A shipping container ~as constructed according to the invention. The outer sleeve .

:, . , :

~, was formed of a triple wall 1500 AAA grade corrugated fibreboard. The outer sleeve had an octagonal cross section and was approxi-mately 40 inches across and 44 inches high.
The inner sleeve was also formed from triple wall 1500 (Beach puncture test rating) AAA
grade corrugated fibreboard material bent into a circular cylindrical shape with random scores. Single wall bottom end flaps were employed. An octagonal-shaped bottom pad formed from 0900 AAA grade corrugated fibreboard and a top end cap of 275~ single wall, fluted fibreboard was utilized to close the ends of the outer sleeYe ~ plastic liner bag, filled with 220 gallons of water, was inserted into the container. A top pad composed of a triple wall 0900 AAA grade corrugated fibreboard having an octa-gonal shape was placed on top of the liner bag to substantially fill the void between ` the liner bag and the top end cap. Three 3/4-inch x .020 inch size steel strappings were used to attach the con~ainer to a 2-way entry wooden pallet 44 x 44 inches. TWo straps were placed in the same direction and one strap was placed crosswise over the other two. Each strap was mounted on a five inch wide brace of 16 gauge beaded sheet metal with three-inch long legs.
The container was tested using a distri-bution cycle pa~terned after ASTM standard D-4169, distribution cycle no. 11 rail, ` trailer on flat car to simulate handling, vertical linear motion, loose-load-rotary ~` 35 motion vibration and rail switching. The ' liquid was retained within the liner bag without leakage throughout the entire test procedure.

(A) Handling Drc>p Test In the drop test, the container was raised six inches off of a concrete floor by means of a fork lift and dropped on edge.
The test was repeated on the opposite edge.
lQ No leakage occured.

(B) Vertical Linear Motion Vibration Tests The container was subjected to vertical linear motion vibration by placing i~ on the table of a vertical linear motion vibration tester having a table displacement of 1.0 inch. The low and medium vibration emported in vertical linear vibration testing simulates truck transit conditions and determines whether destructive resonance of the container will occur. The container was horizontally restrained. The container was placed on the table and subjected to 260 cpm for 40 minutes. The container was then placed on an a higher vibration machine, again restrained in the horizontal direction, and subjected to 40 minutes of vertical linear vibration at tbe following frequencies and displacements:

.

~B~

Test FrequencyDisPlacement (m~Fes) (hertz)(lnches) 13 0.12 21.8 0.07 33.3 0.05 1~ 36.3 0.02 No leakage occured throughout the vertical linear motion vi~ra~ion testing.

(C) Loose Load-Rotary Motion Vibration Test The container was also placed on a rotary motion vibration machine with a table displacement of 1.0 inch. The rotary vi~ration test simulates the side-to-side lS motion which commonly occurs in rail trans-port or piggy back shipments. The container was vibrated for twenty minutes at a frequency of 235 rpm. It was then rotated ninety degrees and vibrated for another twenty minutes at 235 rpm. No leakage occured.
:` ~
(D) Rail Switching-Incline Impact Test The container was placed on the dolly of an incline-impact machine for impact against !, ~;~ a bulkhead to simulate train car bumping. A
~` second container (also filled) was placed behind the first container. The container was subjected to one impact of 4 mph and two impacts of 6 mph. No leakage occured.
;
:

:-: ;, ~ , EXAMPLE II
A shipping container was constructed according to the invention ~as set forth in Example I) for testing after being subjected to adverse humidity conditions. A plastic liner bag was filled with 220 gallons of water and inserted into the container.
The container was conditioned for 72 hours at 90F and a relative humidity of 90~. After 72 hours the conditioned container was compression tested to si~ulate container stacking. A load was applied by a top platen travelling downwardly at a speed of O.S inch per minute until the container failed. Failure did not occur until a load of 8,600 pounds was reached.

EXAMPLE III
A container constructed as in Example I
was conditioned for 72 hours at 73F and a relative humidity of 50%. A plastic liner bag was filled with 220 gallons of water and inserted into the container. ~ load was applied as set forth in Example II. Failure of the container did not occur until a load of 18,000 pounds was reached.

It is a particular feature of the container according to the invention that the inner sleeve 12 may be filled with a bulk flow~ble material without bulging.
This is due to the circular cross section of the inner sleeve 12, which transmits the pressure from the flowable load, purely into hoop stress in the walls of the inner sleeve 12, inherently resisting any bulging of those walls.

. : -,: . ~
- . :.
.

The outer sleeve 14, clue to its construction from a double wall or triple wall corrugate~ fibreboara, is aaptea to resist endwise crushing loaas, permitting a number of such containers to be stackea one upon the other.
The enhanced capability of the heavy-duty shipping container to accommodate and withstand static ana cyclic loads is attributable to a structure which utilizes a circular multi-wall fibreboard inner sleeve and an outer multi-wall fibreboard container against which the inner sleeve bears. Constructions utilizing solia fibre or single wall (double face) corrugated fibreboara inner and outer sleeves are not suitea to use as heavy-duty shipping containers ana are outside of the scope of the invention.
The term "heavy auty" is used herein to aefine containers designe~ to accornr,lodate bulk flowable materials in volumes of at least 55 gallons and weights of 450 pounds and greater. ; ;~
The shipping container design described herein, when utilized in conjunction with a plastic liner bag, is suitable for liquiâs and dry, flowable products in volumes of 55 gallons up to 380 gallons, liquid measure. Liquids and suspensions which weigh as much as 12.5 lbs. per gallon and flowable dry solids which weigh as much as 115 lbs. per cubic foot can be effectively container in fibreboard containers of this design in those volumes.
The upper edge of inner sleeve 12 is initially positioned above the upper edge of outer sleeve 14, by an amount which is less than the thickness of bottom pad 98.
; This is done so that when bne conta1ner of the present ~ ~

.` .

invention is stackeo upon another, the lower container .iill -.ave its inner sleeve 12 pushed aownwarGly, deforming the outer ~eriphery or bottom paG ~. In this way, both the inner and the outer sleeves contribute tO the column strength of the lower container when the sleeves are in the post-loaded position.

-: i :'.-: ~ -:

. . .
.: : .~,. - .
,. : . :. , .

Claims (31)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heavy-duty shipping container for flowable bulk materials comprising:

an outer sleeve vertically extending between a bottom edge and a top edge, said outer sleeve having a polygonal cross-section and comprising a plurality of sidewall panels;

an inner sleeve, substantially coaxially mounted in the outer sleeve, and vertically extending between a bottom edge and a top edge, said inner sleeve having a substantially circular cross section;

the inner sleeve bearing centrally along each of the sidewall panels;

the inner sleeve and outer sleeve each comprising a multi-wall corrugated fibreboard; and support means, mounted within the outer sleeve and underlying the bottom edge of the inner sleeve, for positioning the top edge of the inner sleeve initially higher than the top edge of the outer sleeve, said support means being deformable responsive to pressure applied to the inner sleeve so that the inner sleeve moves downwardly to a post-loading position in which the top edges of the inner and outer sleeves are in the same horizontal plane, whereby each of the inner and outer sleeves can accom-modate a portion of the load of a similar container stacked thereon.

2. A heavy-duty shipping container according to claim 1 , wherein the support means comprises a bottom pad having a polygonal cross section complimentary to the cross section of the outer sleeve, said bottom pad having peripheral edges being of such size as to be continguous to the sidewall panels.

3. A heavy-duty shipping container according to claim 2 , wherein the bottom pad comprises corrugated fibreboard.

4. A heavy-duty shipping container according to claim 2 , wherein the bottom pad comprises triple wall corrugated fibreboard.

5. A heavy-duty shipping container according to claim 2, wherein the inner sleeve is flapless.

6. A heavy-duty shipping container according to claim 1, further comprising a bottom flap attached to each of the sidewall panels along a foldline along the bottom edge of the outer sleeve, the bottom flap underlying the supporting means.

7. A heavy-duty shipping container according to claim 1, wherein in the initial position the top edge of the inner sleeve extends higher than the top edge of the outer sleeve for a distance not exceeding the thickness of the bottom pad.

8. A heavy-duty shipping container according to claim 2, further comprising a bottom flap attached to each of the sidewall panels along a foldline along the bottom edge of the outer sleeve, the bottom flap underlying the supporting means.

9. A heavy-duty shipping container according to claim 8, wherein the inner sleeve is flapless.

10. A heavy-duty shipping container according to claim 6, wherein the bottom flap comprises single wall corrugated fibreboard.

11. A heavy-duty shipping container according to claim 3, in which each of the inner and outer sleeves comprises corrugated fibreboard having flutings which extend vertically and the bottom pad comprises flutings which extend normal relative to the flutings of the inner and outer sleeves.

12. A heavy-duty shipping container according to claim 2, wherein in the post-loading position the bottom pad includes a central position and peripheral position which is vertically depressed relative to the central portion, the bottom edge on the inner sleeve being mounted on the peripheral portion intermediate the central portion and the sidewall panels of the outer sleeve.

13. A heavy-duty shipping container according to claim 1, wherein the support means comprises bottom flaps connected along fold lines to the sidewall panels.

14. A heavy-duty shipping container for flowable bulk materials comprising:

an outer sleeve vertically extending between a bottom edge and a top edge, said outer sleeve having a polygonal cross-section and comprising a plurality of sidewall panels;

an inner sleeve, substantially coaxially mounted n the outer sleeve, and vertically extending between a bottom edge and a top edge, said inner sleeve having a substantially circular cross section;

the inner sleeve bearing centrally along each of the sidewall panels;

the inner sleeve and outer sleeve each comprising a multi-wall corrugated fibreboard;

support means, mounted within the outer sleeve and underlying the bottom edge of the inner sleeve, for positioning the top edge of the inner sleeve initially higher than the top edge of the outer sleeve, said support means being deformable responsive to pressure applied to the inner sleeve so that the inner sleeve moves downwardly to a post-loading position in which the top edges of the inner and outer sleeves are in the same horizontal plane, whereby each of the inner and outer sleeves can accommo-date a portion of the load of a similar container stacked atop the said container; and the inner sleeve having an inner circumferential facing with a multiplicity of false scores extending vertically along the sleeve.

15. A heavy-duty shipping container according to claim 14, wherein the inner sleeve comprises a triple wall corrugated fibreboard.

16. A heavy-duty shipping container according to claim 14, wherein the circular inner sleeve comprises a sheet of triple wall corrugated fibreboard formed by the steps of passing the sheet through a curved path so as to impart a curvature to the corrugated sheet to cause the randomly spaced formation of multiple false scores on the inner circumferential facing of the inner sleeve in the direction of the corrugations, overlapping edges of the sheet, and adhesively securing the overlapped edges to each other.

17. A heavy-duty shipping container according to claim 14, wherein the outer sleeve has an octagonal cross section.

18. A heavy-duty shipping container according to claim 14, wherein the outer sleeve comprises triple wall corrugated fibreboard and the inner sleeve comprises triple wall corrugated fibreboard.

19. A heavy-duty shipping container according to claim 18, wherein the outer sleeve has a octagonal cross section.

20. A heavy-duty shipping container according to claim 19, wherein the inner sleeve is formed by the steps of passing the sheet through a curved path so as to impart a curvature to the corrugated sheet to cause the randomly spaced formation of multiple false scores on the inner circumferential facing of the inner sleeve in the direc-tion of the corrugations, overlapping edges of the sheet, and adhesively securing the overlapped edges to each other.

21. A heavy-duty shipping container according to claim 20, wherein the false scores of the inner sleeve are spaced from one to six inches apart.

22. A heavy-duty shipping container according to claim 21, further comprising a plurality of bottom flaps, each bottom flap being foldably connected to a respective one of the sidewall panels at the bottom edge of the outer sleeve, each of the bottom flaps comprising a single wall corru- gated fibreboard, and each of the bottom flaps being folded inwardly of the outer sleeve beneath the support means.

23. A heavy-duty shipping container according to claim 22, further comprising a bottom pad, the bottom pad having an octagonal cross section, and the bottom pad being mounted on the bottom flaps intermediate the bottom flaps and the inner sleeve.

24. A heavy-duty shipping container according to claim 23, wherein the bottom pad has a peripheral edge mounted against the sidewall panels of the outer sleeve.

25. A heavy-duty shipping container according to claim 24, wherein the bottom pad comprises triple wall corrugated fibreboard.

26. A heavy-duty shipping container according to claim 25, further comprising bag means for containing the flowable materials mounted within and substantially filling the inner sleeve.

27. A heavy-duty shipping container according to claim 26, further comprising a top pad, and an end cap mounted on the top edges of the outer sleeve and inner sleeve, the top pad having a circular cross section, the top pad being mounted within the inner sleeve intermediate the bag means and the end cap, and wherein the top pad has a circular periphery in engagement with the inner sleeve.

28. A heavy-duty shipping container according to claim 27, wherein the top pad comprises a triple wall corrugated fibreboard panel.

29. A heavy-duty shipping container according to claim 27, wherein the top pad comprises a compressible polyether foam panel.

30. A heavy-duty shipping container according to claim 27, wherein the end cap has a cross section similar to the cross section of the outer sleeve, the end cap having peripheral side flanges which overlie the sidewall of the outer sleeve and further comprising a plurality of inverted U-shaped braces mounted to the end cap, each brace including a central portion overlying the end cap intermediate the flanges of the end cap and depending legs overlying opposite flanges of the end cap, a pallet, and strap means overlying the braces for holding the container to the pallet.

31. A heavy-duty shipping container according to claim 1 or 2 or 4 or 14 or 15 further comprising bag means for containing flowable materials within and substantially filling the inner sleeve.