US3893567A

US3893567A - Vertical stacker

Info

Publication number: US3893567A
Application number: US280962A
Authority: US
Inventors: Paul Davis; David N Shore
Original assignee: Sweetheart Plastics
Current assignee: SWEETHEART PROPERTIES Inc; Solo Cup Operating Corp
Priority date: 1972-08-16
Filing date: 1972-08-16
Publication date: 1975-07-08
Anticipated expiration: 1992-07-08

Abstract

A thin wall, disposable, plastic container or cover having a nesting facility comprised of a lower shoulder, an upper shoulder, and an intermediate side wall. Protrusions are formed in the intermediate side wall which extend radially from the side wall the full axial extent of said side wall, and the circumferential width of the protrusions is equal to the space between them. In accordance with one embodiment of this invention, the different containers or covers are formed with different numbers of protrusions.

Description

United States Patent 1 Davis et al.

[ VERTICAL STACKER [75] Inventors: Paul Davis, Swampscott; David N.

Shore, Brookline, both of Mass.

[73] Assignee: Sweetheart Plastics, lnc.,

Wilmington, Mass.

[22] Filed: Aug. 16, 1972 [21] Appl. No.: 280,962

{52] US. Cl. 206/520; 229/15 B [51] Int. Cl. B6Sd 21/02 [58] Field of Search 220/97 C, 97 F; 229/l.5 B,

[56] References Cited UNITED STATES PATENTS 3,045,887 7/l962 Caine 229/15 B 3,06l,l39 10/1962 Edwards... 220/44 R 3,401,862 9/1968 Wanderer 229/l.5 B

[451 July 8,1975

3,484,018 12/1969 220/l.5 B 3,596,795 8/l97l D'Ercoll 229/15 H 3,654,076 4/1972 Hatch 220/97 C Primary Examiner-George E. Lowrance Attorney, Agent, or Firm-Wolf, Greenfield & Sacks [5 7 ABSTRACT A thin wall, disposable, plastic container or cover having a nesting facility comprised of a lower shoulder, an upper shoulder, and an intermediate side wall. Protrusions are formed in the intermediate side wall which extend radially from the side wall the full axial extent of said side wall, and the circumferential width of the protrusions is equal to the space between them. In accordance with one embodiment of this invention, the different containers or covers are formed with different numbers of protrusions.

8 Claims, 11 Drawing Figures la 24 24 I8 24 24 24 I8 VERTICAL STACKER This invention relates to nestable containers and covers and more particularly comprises a new and improved stacking facility for containers and covers, which prevent the articles from jamming when axial loads are applied to them.

BACKGROUND OF THE INVENTION In the past years considerable research and development has been directed to the design of stacking facilities in thin wall, nestable articles such as containers and covers to prohibit them from jamming when axial loads are applied to a stack of the nested articles. This work has been prompted by the rapidly growing use of disposable thermoformed plastic containers and covers, many of which are handled automatically in vending machines and in automatic filling equipment.

Most of the developments of stacking facilities for thin wall, thermoformed, plastic articles such as containers have been in the form of undercuts wherein the upper margin or shoulder of the undercut is supported at its inner edge by an upwardly and inwardly inclined intermediate wall, so as to create an interference between the upper and lower shoulders of adjacent containers, which interference exceeds the stock thickness of the plastic material.

There are certain disadvantages, however, to undercut stacking rings of that type. For example, undercuts make it difficult to remove the containers from the cavities after the containers are formed, and special strippers are necessary to eject the containers from the cavities. Another disadvantage of stacking facilities having undercuts is the difficulty in actually forming their details. And if the details of the stacking facilities are not formed well, the articles will likely jam when an axial load is applied.

One important object of this invention is to provide a stacking facility which is free of undercuts and which nevertheless maximizes the interference of the stacking rings of adjacent articles so as to minimize the possibility of jamming of adjacent articles.

In accordance with the present invention the stacking ring is composed ofa lower shoulder formed in the side wall, that may or may not be coincident with the article bottom. An upper shoulder is formed in the article side wall above the lower shoulder, and the axial space between the shoulders determines the pitch or stack height of the nested articles. An intermediate wall joins the outer edge of the lower shoulder and the inner edge of the upper shoulder, and this wall is either vertical or slightly inclined upwardly and outwardly with respect to the article axis. A plurality of protrusions are formed in the intermediate wall, which extend the full axial height thereof, and the protrusions are spaced apart about the intermediate wall a distance substantially equal to their own circumferential width. In accordance with one aspect of this invention, the articles which are intended to be nested together all have the abovespecified features, but in addition, the number of protrusions in adjacent articles in a nest are different.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side view of a pair of nested containers constructed in accordance with this invention and partially broken away to reveal their nesting facilities;

FIG. 2 is an enlarged fragmentary cross-sectional view of the nesting facilities of the two containers shown in FIG. 1',

FIG. 3 is a diagrammatic representation of the nesting facility of the cups in FIGS. 1 and 2;

FIGS. 4 and 5 are diagrammatic representations similar to FIG. 3 of other embodiments of this invention;

FIG. 6 is a diagrammatic representation of the manner in which the nesting rings of two identical contain ers of the type shown in FIGS. 1-3 cooperate to prevent jamming with the profiles offset for clarity;

FIG. 7 is a diagrammatic representation similar to FIG. 6 but showing the manner in which nesting rings of two dissimilar containers of the types shown in FIGS. 3 and 5 nest together;

FIG. 8 is an enlarged fragmentary view of two thin wall, plastic lids constructed in accordance with this in vention',

FIG. 9 is a fragmentary bottom view of one lid of FIG. 8;

FIG. 10 is a fragmentary bottom view of yet another lid in accordance with this invention; and

FIG. 11 is a diagrammatic representation of yet another container constructed in accordance with this invention.

DETAILED DESCRIPTION The container shown in FIG. I typically may be a 3.5 oz. container, and it has a side wall 10, bottom wall [2, rolled rim l4, and a nesting facility 16. The side and bottom walls are integrally formed (typically on thermoforming equipment) and the stock thickness may be in the range of 0.005 to 0.020 inches after forming. This stock thickness range is merely exemplary and is not intended in any way to limit the scope of this inven tion. However, as expressed in the introduction, this invention has particular application to thin wall, nestable containers where stock thickness itself is insufficient to provide positive nesting without some likelihood of jamming.

The nesting facility 16 shown in FIGS. 1-3 includes an upper shoulder 18, lower shoulder 20, and intermediate side wall 22. In this embodiment, the intermediate side wall 22 is vertically disposed (cylindrical with respect to the cup axis), but this wall may taper outwardly somewhat to create a draft in the container which would facilitate stripping from the mold. The wall 22 is not undercut, which would positively interfere with cup stripping after forming.

It will be appreciated that if the container shown in FIG. 1 about its entire circumference had upper and lower shoulders and intermediate side walls which were uninterrupted so that the radial width of the shoulders was uniform throughout a full 360, when two cups of like design were nested one in the other, the only interference between the upper and lower shoulders of the two adjacent containers would be the thickness of the stock, i.e. the thickness of vertical intermediate wall 22. If the stock thickness were in the range of 0.005 to 0.020 inches, and the material was a typical high impact styrene used in the disposable container industry, an axial load applied to the containers would cause the material in the nesting rings to distort, and the lower shoulder of the upper container would pass within intermediate wall 22 of the next lower container, and the two containers would jam together. When jammed, the cups cannot easily be stripped apart and likely will cause malfunctioning of vending mechanisms or feeding mechanisms which are intended to automatically feed the cups one at a time from the stack.

In accordance with the present invention, the intermediate wall 22 is provided about its circumference with protrusions 24 whose width is circumferentially equal to the space between the protrusions. That is, as shown in FIG. 3, the protrusion 24 measured from point A to point B is equal in circumferential width to the space between adjacent protrusions 24 measured from point B to point C.

In the embodiment shown, the protrusions 24 are described by

radii

26 and 28 and arcuate wall 30. The

radii

26 and 28 define relatively

sharp corners

32 and 34 with the cylindrical intermediate wall 22. The radii may be reversed so that they form sharp corners with the arcuate wall and merge smoothly with the intermediate wall 22. In this arrangement, the protrusions effectively extend radially in rather than out from the intermediate wall.

Typically the protrusions 24 may be approximately .040 inches, and the points A, B and C are determined by the intersection of an arc lying midway between the maximum depth of the protrusions and the circumferential intermediate wall 22; that is, an are 0.020 inch beyond the intermediate wall 22.

In the embodiment of FIG. 3, the distance A to B, and the distance B to C may be 36". Thus, about the entire circumference of the cup, five protrusions and five spaces are formed. In FIG. 6 the nesting rings of two such containers as shown in FIG. 3 are suggested, 18 out of phase with one another. When the two contain ers are out of phase one quarter cycle (one cycle being equal to the circumferential width of one protrusion and one intervening space) there is substantial interference between the uninterrupted portion of the upper shoulder of the lower container and the bottom wall of the protrusion of the upper container. Referring to FIG. 2, it will be noted that the lower wall 36 ofthe protrusion will rest upon the portion 38 of the upper shoul der supported by the portion of the intermediate side wall between protrusions. When the protrusions are made equal in circumferential width to the spaces between adjacent protrusions, maximum interference will exist between the upper shoulder of the bottom container and the lower shoulder of the container above, so long as they are out of phase with one another. And regardless of the relative angular positions of the two containers, the support given by the lower container to the upper one will be spaced equally about the con tainer circumference. It will be appreciated that the interference between the two containers is provided by the protrusion of the upper container resting on the gap between protrusions in the next lower container, and maximum interference is assured therefore only when the interrupted and uninterrupted portions are of equal circumferential width.

When adjacent containers in a nest are oriented with their depressions in phase with one another, the only resistance to jamming is derived from stock thickness, which is not dependable to maintain the cups readily separable from one another. While it is not likely that adjacent cups will become circumferentially aligned when stacked in random so that their protrusions and intermediate spaces are completely in phase, occasionally this may occur, and to further resist jamming, it is proposed to manufacture containers to be stacked together with different numbers of protrusions. This is illustrated in FIGS. 3, 4 and 5. In FIG. 3 as described above, one cycle composed of a protrusion and gap is 72, and five such combinations are present about the cup periphery. In FIG. 4 the cycle composed of protru sion and gap 52 is 5126, which provides 7 protrusions and 7 gaps about the cup periphery. In FIG. 5 the cycle composed of protrusion and gap 62 spans 40, and consequently 9 such pairs are provided about the cup periphery.

It is evident as shown in FIG. 7 that when a cup of the variety shown in FIG. 3 is placed immediately adjacent to and nested with a cup having a nesting ring as shown in FIG. 5, interference must exist between the upper shoulder of the lower container L and the lower shoulder of the upper container U, and the interference area exceeds the cross-sectional area of the stock. Even if protrusion 60 of the upper container is aligned with the protrusion 24 of the lower container at one point about the periphery, other protrusions will lie above and rest upon uninterrupted portions of the upper shoulder of the lower container. When the cups are dissimilar it is not possible to align all the protrusions of the upper container with protrusions below, as they are not of the same size or number. Similarly, when containers as shown in FIG. 4 are mixed with those in FIGS. 3 and 5, jamming of adjacent containers is also prevented. It is proposed that a multiple cavity mold be provided with different nesting rings having different numbers of protrusions. Typically a multi-cavity mold may include 6 or 7 different sizes of protrusions, and such a configuration will greatly reduce the likelihood of identical cups with like numbers of protrusions being nested im mediately adjacent one another when the cups are stacked.

From the foregoing description it will be appreciated that the several objects of this invention are achieved by the use of protrusions and gaps of equal size and by varying the number of protrusions and gaps in containers nested adjacent one another. In such an arrangement the likelihood ofjamming is virtually nil, and the cross sectional area of the interfering surfaces of upper and lower shoulders may equal or exceed that achieved in conventional undercut nesting rings typical of the prior art.

In FIGS. 8 and 9 this invention is shown embodied in a thin wall, disposable, plastic lid. In FIG. 8, two such lids are shown nested together in the manner of the two containers of FIG. 2. Thus, each lid which includes a closure wall 82, side wall 84, flange 86, and skirt 88 is also provided with a nesting recess 90 that functions in the same manner as the nesting facilities in the containers of FIGS. 1-5. The lid itself in combination with a container functions conventionally as a coverall lid to cover the rim and seal the container. The channel 92 defined by the flange 86, side wall 84, and skirt 88 receives the rim of the container and forms a seal with it.

The recess 90 is defined by an inner cylindrical wall 94 and a second outer cylindrical wall 96. Wall 96 is provided with protrusions 98 formed like the protrusions in the embodiments of FIGS. l-S. The circumferential width of each protrusion 98 is equal to the gap between the protrusions measured in the fashion described above in connection with the containers. When identical lids are nested together as shown in FIG. 8, lower wall 102 of the protrusion forms a lower shoulder which rests on the upper shoulder 100. If the width of the protrusions and gaps between protrusions are equal, uniformly distributed interference is achieved when the lids are nested together.

While the protrusions are shown in the embodiment of FIGS. 8 and 9 formed on the outer cylindrical wall 96 of the nesting recess 90, it is evident that the protrusions may be alternatively formed on the wall 94 as well. That arrangement is shown in the embodiment of FIG. 10, wherein nesting recess 110 has a continuous uninterrupted cylindrical outer wall 2 and an interrupted inner cylindrical wall I14 with protrusions H6. When the lids are nested together, protrusions 116 of the upper lid rest on the shoulder defined by the gap between the protrusions in the lower lid. Thus, the lids will nest in the same manner as the lids of FIG. 8.

As suggested above, the protrusions formed in the walls to assure nesting may either extend radially in or out from the circumferential intermediate wall. In FIG. 11 such an arrangement is shown for a container otherwise the same as the containers of FIGS. 1-5. In this embodiment, the intermediate side wall of the nesting ring 120 is provided with protrusions 122 formed at their ends by

arcuate walls

124 and 126. As in all the other embodiments, the circumferential width of the protrusions is equal to the space between them.

It will be appreciated that in the embodiments shown in FIGS. 8-11, different numbers of protrusions may be formed in different containers or lids to further insure against jamming. That is, the protrusions and the nesting recesses may be of different numbers as suggested in FIGS. 3-5 so that adjacent lids or containers in a nest may have different numbers of protrusions so as to positively prevent jamming.

Having described this invention in detail, those skilled in the art will appreciate that numerous modifications may be made of the invention without departing from its spirit. Therefore, I do not intend to limit the scope of this invention to the several embodiments illustrated and described. Rather, it is intended that the scope of this invention be determined by the appended claims and their equivalents.

What is claimed is:

l. A one-piece, thin wall, disposable, plastic article comprising an outwardly inclined axially extending wall and a transverse wall integral with the axially extending wall,

and a nesting facility formed in the axially extending wall, said nesting facility having a lower external shoulder and an upper internal shoulder,

a substantially vertical disposed intermediate wall section interconnecting the inner radial edge of one shoulder and the outer radial edge of the other,

a plurality of substantially vertically disposed protru sions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each protrusion has a circumferential width equal to the circumferential width of each intermediate wall portion between each protrusion, with said protrusions acting to provide a stacking interference at equally spaced portions about the circumference of the article when it is stacked with a similar article out of circumferential phase therewith,

said intermediate wall section being free of undercuts between the upper and lower shoulders.

2. In combination with the article of claim 1, at least one additional article nested therewith and characterized as set forth in said claim, said articles being further characterized by at least some of said articles having different numbers of protrusions.

3. A one-piece, thin wall, disposable, plastic article defined in claim 1 further characterized by said article being a container and said intermediate wall section lying in the axially extending wall.

4. A one-piece, thin wall, disposable, plastic article comprising,

an axially extending wall and a transverse wall integral with the axially extending wall,

a nesting facility formed in a recess in the transverse wall, said nesting facility having, a lower external shoulder and an upper internal shoulder.

a substantially vertically disposed intermediate wall section defining one side of said recess and interconnecting the inner radial edge of one shoulder and the outer radial edge of the other,

a plurality of substantially vertically disposed protrusions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each protrusion has a circumferential width equal to the circumferential width of each intermediate wall portion between each protrusion, with said protrusions acting to provide a stacking interference at equally spaced portions about the circumference of the article when it is stacked with a similar article out of cir cumferential phase therewith,

said intermediate wall section being free of undercuts between the upper and lower shouldersv 5. A one-piece, thin wall, disposable, plastic article as defined in claim 4 further characterized by said article being a lid and having a flange extending outwardly from said axially extending wall and having a skirt extending downwardly from the outer edge of the flange, said axially extending wall, flange, and skirt enclosing the rim of a container when fitted on itv 6. A one-piece, thin wall, disposable, plastic contamer comprising a bottom and an outwardly inclined upwardly extending side wall integrally formed from a thin sheet of plastic material and joined at a bottom edge, said container having a nesting facility characterized by:

a lower external shoulder formed in the side wall that may be coincident with the container bottom and an upper internal shoulder spaced above the lower shoulder in said side wall,

a substantially vertically disposed intermediate wall section interconnecting the inner radial edge of the upper shoulder and the outer radial edge of the lower shoulder, said intermediate wall having an inner diameter at the upper shoulder at least as great as the inner diameter at the lower shoulder,

a plurality of protrusions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each wall whose center is coincident with the axis of the container.

said protrusions being further characterized by radii which merge smoothly into the arcuate wall and define sharp corners with the intermediate wall.

8. In combination with the container of claim 6,

at least one additional container nested therewith and characterized as set forth in said claim, said containers being further characterized by at least some of said containers having different numbers of protrusions.

Claims

1. A one-piece, thin wall, disposable, plastic article comprising an outwardly inclined axially extending wall and a transverse wall integral with the axially extending wall, and a nesting facility formed in the axially extending wall, said nesting facility having a lower external shoulder and an upper internal shoulder, a substantially vertical disposed intermediate wall section interconnecting the inner radial edge of one shoulder and the outer radial edge of the other, a plurality of substantially vertically disposed protrusions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each protrusion has a circumferential width equal to the circumferential width of each intermediate wall portion between each protrusion, with said protrusions acting to provide a stacking interference at equally spaced portions about the circumference of the article when it is stacked with a similar article out of circumferential phase therewith, said intermediate wall section being free of undercuts between the upper and lower shoulders.

3. A one-piece, thin wall, disposable, plastic article as defined in claim 1 further characterized by said article being a container and said intermediate wall section lying in the axially extending wall.

4. A one-piece, thin wall, disposable, plastic article comprising, an axially extending wall and a transverse wall integral with the axially extending wall, a nesting facility formed in a recess in the transverse wall, said nesting facility having, a lower external shoulder and an upper internal shoulder, a substantially vertically disposed intermediate wall section defining one side of said recess and interconnecting the inner radial edge of one shoulder and the outer radial edge of the other, a plurality of substantially vertically disposed protrusions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each protrusion has a circumferential width equal to the circumferential width of each intermediate wall portion between each protrusion, with said protrusions acting to provide a stacking interference at equally spaced portions about the circumference of the article when it is stacked with a similar article out of circumferential phase therewith, said intermediate wall section being free of undercuts between the upper and lower shoulders.

5. A oNe-piece, thin wall, disposable, plastic article as defined in claim 4 further characterized by said article being a lid and having a flange extending outwardly from said axially extending wall and having a skirt extending downwardly from the outer edge of the flange, said axially extending wall, flange, and skirt enclosing the rim of a container when fitted on it.

6. A one-piece, thin wall, disposable, plastic container comprising a bottom and an outwardly inclined upwardly extending side wall integrally formed from a thin sheet of plastic material and joined at a bottom edge, said container having a nesting facility characterized by: a lower external shoulder formed in the side wall that may be coincident with the container bottom and an upper internal shoulder spaced above the lower shoulder in said side wall, a substantially vertically disposed intermediate wall section interconnecting the inner radial edge of the upper shoulder and the outer radial edge of the lower shoulder, said intermediate wall having an inner diameter at the upper shoulder at least as great as the inner diameter at the lower shoulder, a plurality of protrusions formed in the intermediate wall extending the full axial height thereof, said protrusions being spaced apart about the intermediate wall a distance substantially equal to the circumferential width of the protrusions so that each protrusion has a circumferential width equal to the circumferential width of each intermediate wall portion between each protrusion, with said protrusions acting to provide a stacking interference at equally spaced portions about the circumference of the article when it is stacked with a similar article out of circumferential phase therewith, said intermediate wall being free of undercuts between the upper and lower shoulders.

7. A one-piece, thin wall, disposable, plastic container as described in claim 6 further characterized by each of said protrusions being defined by an arcuate wall whose center is coincident with the axis of the container, said protrusions being further characterized by radii which merge smoothly into the arcuate wall and define sharp corners with the intermediate wall.

8. In combination with the container of claim 6, at least one additional container nested therewith and characterized as set forth in said claim, said containers being further characterized by at least some of said containers having different numbers of protrusions.