United States Patent 3616943

A body such as a box may be stacked with substantial rigidity and provided with the capability of spacing and staggering by providing single and/or multiple rows of protuberances such as beads on upper and lower surfaces arranged so that the beads nest or interlock upon stacking.

Application Number:
Publication Date:
Filing Date:
W. R. Grace & Co. (Cambridge, MA)
Primary Class:
Other Classes:
206/509, 206/511, 206/821, 426/419, 446/128
International Classes:
B65D21/02; (IPC1-7): B65G1/14
Field of Search:
214/10.5 206
View Patent Images:
US Patent References:
3393858Rectangular collapsible carton for the shipment of bananas1968-07-23Heel
3371816Collapsible receptacle1968-03-05Ricci
3005282Toy building brick1961-10-24Christiansen
2849151Stacking container1958-08-26Heil

Foreign References:
Primary Examiner:
Forlenza, Gerald M.
Assistant Examiner:
Werner, Frank E.
I claim

1. A stackable body comprising; an upper surface and a lower surface each of said surfaces being capable of adjacentwise coincidence with at least one of them; at least one first row group comprising at least one row of equally spaced protuberances; at least one second row group comprising at least two rows of said equally spaced protuberances; the row groups being mounted on pads upon the body and oriented upon the surfaces so that upon stacking by adjacentwise coincidence of the surface the protuberances of each first row group are axially interposed between and in offset contact with the protuberances of a second row group.

2. The stackable body of claim 1 wherein the protuberances are of diminishing circular cross section and are equally spaced both axially and transaxially of the rows.

3. The stackable body of claim 2 wherein the protuberances are semispherical in shape.

4. The stackable body of claim 3 wherein the body is foamed agglutinated polystyrene granules.

5. The stackable body of claim 4 wherein an average of at least five granules extend across the greatest diameter of the protuberances.

6. A stackable body comprising an upper and lower surface, each of said surfaces being capable of adjacentwise coincidence with at least one of them; at least one first row group comprising at least one row of equally spaced protuberances; at least one second row group comprising at least two rows of said equally spaced protuberances; the row groups being oriented upon the surfaces so that upon stacking by adjacentwise coincidence of the surfaces the protuberances of each first row group are axially interposed between and in offset contact with the protuberances of the second row group and the protuberances are of diminishing circular cross section are equally spaced both axially and transaxially of the rows a distance such that the protuberances are interposed in contact without bottoming on the surfaces.

7. The stackable body of claim 6 wherein the body is rectangular in plan having a single planar upper surface and a single planar lower surface and having row groups extending parallel to one dimension of the rectangle along the edges thereof.

8. The stackable body of claim 7 further comprising a row group extending centrally of the rectangle and parallel to the other row groups.

9. The stackable body of claim 7 wherein the row groups are mounted on pads upon the body.


The invention relates to stackable bodies in particular to container boxes which are to be stacked wherein it is desired that a rigid stack or formation of stacks be formed. In particular, the invention relates to such bodies which may be stacked in staggered or overlapped formation to an optional degree with or without spaces between the bodies. In one particularly advantageous embodiment, boxes molded of foamed, agglutinated polystyrene beads are provided with the stacking means of the invention.

In the past it has been known to permit rigid stacking of bodies such as container boxes by shaping them so that some portion of the bottom of one container is captured by the top of another identical container, or visa versa, as in nesting. One common form is where the lower portion of the container is smaller than its upper portion, as by being tapered, and the latter has a cavity for receiving an identical container up to some desired depth. This form is excellent for forming single stacks of empty containers such as nested drinking cups. However, it is inefficient when it is desired to stack filled containers or solid bodies since the space needed to nest is not available for the basic purpose of the container or body. Furthermore, this stacking means only permits single stacks to be formed which must then, if a rigid multistack formation is desired, be joined by some other means such as tying or wrapping, e.g. if more than one stack is desired to be transported. If spacing is desired between containers this can be accomplished only by quite inconvenient spacers between stacks and spacing is effectively impractical within a stack.

Some of these problems have been alleviated by another form of stacking means in which projections or legs are provided at the bottom corners of the container and mating cavities in the top corners. This form permits spacing within a stack but is still ineffective for multistack formations. In addition, in cases where a high degree of rigidity or resistance to dislodgment is desired, it is necessary that the projections and mating cavities be relatively massive and deep thus consuming an undesirably large amount of space.

Other severe disadvantages are that the projections or legs interfere with conveyor systems, are easily broken especially if the container is dropped on a corner; and require careful preparation of the floor to assure equal support for all the legs. The cavities of such systems are often found to contain dirt or debris which interferes with proper functioning.

These and other problems are alleviated in the present invention as will be seen by the following discussion.


FIG. 1 is a perspective view showing the top of a box embodying the invention.

FIG. 2 is a perspective view showing the bottom of the box of FIG. 1.

FIG. 3 is a side view of the rows of interposed beads of the embodiment of FIG. 1.

FIG. 4 is an end view of the rows of interposed beads.

FIG. 5 is an elevation view of boxes of FIG. 1 vertically stacked.

FIG. 6 is a section view through line 6--6 of FIG. 3.

FIG. 7 is a side view of an alternate embodiment of the invention.

FIG. 8 is an end view of the embodiment of FIG. 7.

FIG. 9 is an elevation view of boxes of FIG. 1 stacked with offset and spacing.

FIG. 10 is a perspective schematic view of boxes embodying the invention cross-stacked in a solid formation.

FIG. 11 is a plan view of matrix of FIG. 10.

FIG. 12 is an elevational partially schematic view of another embodiment of the invention.


A stackable body is provided on upward- and downward-facing surfaces with groups of protuberances oriented in rows wherein upon stacking, the rows mate such that the protuberances of one row are axially interposed and offset between the protuberances of another row. The rows are parallel and the protuberances equally spaced so that the bodies may be stacked vertically aligned or may be staggered to form interconnected solid or spaced formations of stacks.


Referring to FIGS. 1 and 2 a form of the invention is shown as employed in a box 1 having an upper surface or top 2 and a lower surface or bottom 4. The top 2 might typically be a removable cover although that would have no consequence as regards the invention except that the cover should be fairly well secured to the box. Upon the top 2 is a series of pads 6 and upon the bottom 4 a series of similar pads 8. Extending from each of the pads 6 are two parallel rows 10 consisting of protuberances 12 in this particular embodiment in the shape of semispherical beads which can be more plainly seen by reference to FIGS. 3 and 4 and more particular mention of which will be made later. Extending from each of the pads 8 are three parallel rows 14 consisting of the same protuberances or beads 12 as in the rows 10. The sets of two and three rows may be conveniently referred to respectively as row groups 10 and 14 or alternatively as matrices. The row groups 10 and 14 are oriented on the upper and lower surfaces 2 and 4 respectively so that when boxes 1 are stacked as shown in FIG. 5 the rows are adjacent and interlock or nest in a manner now to be explained.

In order to exploit all the advantages of the invention all the rows must parallel and the beads must be equally spaced along the axis or the row as shown by the center distance X in FIG. 3. In the preferred embodiment where the protuberances are symmetrical in cross section, the transaxial distance between rows should be the same distance X as shown in FIG. 4. Assuming a datum position for the box 1 as being stacked in vertical alignment as shown in FIG. 5, then the upward-facing row groups 10 will be axially and transaxially offset one-half the center distance X (FIG. 3) from the beads of the downward-facing row groups 14 to be interposed between and in contact with them. The complete interlocking of the thus mating row groups is shown in partial section in FIG. 6 taken through the line 6--6 of FIG. 3. The dimension X may be chosen according to a number of factors which are apparent to those comprehending the invention. It is preferable that the beads be so spaced that contact be accomplished without bottoming that is, contacting the planar surface from which the opposing protuberances extend.

In order to effect the interposition of protuberances it is necessary as a minimum that one of the mating row groups have one row and that the other have two rows; or in other words, that one row group have at least one row and the other row group have at least one more row. As can be seen the interlocking effect will not resist vertical separation of stacked boxes but will resist horizontal movement. The relative resistance to dislodgement can be varied according to the number of rows in each mating row group, the ultimate number of interposed protuberances determining the total contact area and thereby the total force resisting rows dislodgement. The shape of the protuberances is also significant in effecting more or less strength in the stack. For example, the truncated cones 16 shown in FIGS. 7 and 8 would be more resistive than the beads shown in FIGS. 3 and 4. However, one of the essential advantages of the invention is that the protuberances be not easily deformed or broken and that they be of sufficient number to distribute the weight of the box evenly especially when they are not stacked and more importantly as to the bottom box in the stack. Thus they should not protrude excessively for it is in their number that the versatility, stacking strength, and other features of the invention are achieved rather than in their individual ability to resist horizontal movement. This advantage is best achieved when the extension or height of the protuberance is equal to or less than its cross distance or width at the place of joinder to the box.

It would also be possible to provide protuberances within the scope of the invention that would resist vertical dislodgement as well by shaping them for interference fit as by a terminal enlargement.

The bead or semispherical form 12 shown herein is particularly advantageous as the interposed beads show good interlocking and resistance to damage when the bead is hemispherical or less in its protrusion from the box.

This form is especially useful in boxes of foamed agglutinated polystyrene granules (commonly called beads, but not so here to avoid confusion) having been found to be superior to other forms in daily commercial use. The strength of a polystyrene body (of a given density) is most effected by the agglutination of the granules, for it is along the granule boundaries that failure usually occurs. Failure through fracture of the granules is considered to indicate the maximum achievable strength. Normally in production products, failure is at granule boundaries. It would seem then that for maximum strength the beads 12 should be formed of as few granules as possible which would also extend into the box. Thus the protuberance would have less area of granule boundaries and be less susceptible to damage. It has been found to the contrary, however, that such relatively large granules do not work well. They tend to bridge and fail to fill the mold cavity constituting the protuberance. In addition, it has been found that beads formed from a plurality of smaller granules have higher compressive strength and are stronger and more resistant to deformation or splitting at granule boundaries than a few larger granules as long as there is no easy starting point for granule boundary separation. Thus the semispherical bead 12 shown in FIG. 3 with at least about five and preferably about 6-8 polystyrene granules 18 across its width is exceptionally resistant to damage and may be conveniently molded while providing good stacking effectiveness. The truncated cones 16 of FigS. 7 and 8 are not as desirable because the sharp corner is an easy starting point for granule separation. Having described the form of the protuberances and their general and preferred function in stacking there will now be described some of the special capabilities available with the invention. FIG. 5 shows a stack in vertical alignment with maximum interlocking of the matrices. It is noted that the interlocking shown in FIGS. 5 and 9 is partially schematic since in practice, one row is partially hidden as in FIGS. 3 and 4. The boxes 1 can be staggered along the row in increments equal to the center distance X so as to form a staggered spaced formation such as in FIG. 9. The formation need not be spaced but may be solid as shown schematically in FIG. 10 where rectangular boxes having long sides 20 and short sides 22 and row groups as in FIG. 1 are stacked according to the pattern shown in FIG, 11 where the pattern is reversed in alternate levels. The overlap of row groups is shown by the dotted lines indicating a subsequent level where interlocking of protuberances takes place as shown in part in the shaded areas 24.

Ventilation and environmental control are available even with a solid formation by choosing an appropriate size and number of row groups so that there is some space between the interlocked protuberances. At a minimum the channel is the height of the protuberance. More effective ventilation and environmental control is possible by providing the open channels between row groups as described and shown herein, the pads 6 and 8 providing an increased spacing. By adoption of a staggered formation even greater ventilation is possible.

In a commercial application of this preferred embodiment polystyrene box is used for transporting frozen fish. The box is approximately 16× 12inches and has first row groups of two rows on its upper surface; one row group along each of the long sides and one down the center. These row groups are interrupted by a channel across the width at the center to essentially form the six row groups 10 shown in FIG. 1. Second similar row groups 14 are formed on the bottom surface, each having three rows. The beads are seven-sixteenths inch at their greatest diameter, are spaced one-half inch on center, and have a height of about one-eighth inch. The beads tend to become somewhat flattened in use which does not interfere with their nesting function and is in fact advantageous for overcoming irregularities when placing the box on a planar surface. The six first row groups 10 have 13 beads per row and six second row groups 14 have 14 beads per row. Another application of staggered formation is the ability to tightly pack fixed-size transports, such as trucks and trains by merely stacking the boxes at appropriate spacing to tightly pack the space. It is noted that if the center distance between rows of a row group is the same as that along the row axis, then it is possible to use the compound formation of FIGS. 10 and 11 where boxes are turned at right angles.

Rigid stacking of nonsymmetrical bodies can be achieved if mating surfaces are available such as in the embodiment shown in FIG, 12. All that is required is that each surface be capable of adjacentwise coincidence with at least one other surface.

The box 26 has on one side a flat surface 28 and on the other side two surfaces 30 and 32. When stacked, the flat surfaces 28 mate and the surfaces 30 and 32 mate by alternately inverting the boxes. Four row groups 34-40 are provided. It is possible in any case where a flat surface such as 28 is found to stagger and interconnect stacks, although this can be done only to a limited extent with the unsymmetrical surfaces 30 and 32 because the boxes cannot be stacked cross wise in the later case. So many variations are possible within the broad scope of the invention that further explication is unnecessary.