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Publication numberUS3735917 A
Publication typeGrant
Publication dateMay 29, 1973
Filing dateJun 18, 1971
Priority dateApr 27, 1971
Also published asDE2220274A1, DE2220274B2, DE2220274C3
Publication numberUS 3735917 A, US 3735917A, US-A-3735917, US3735917 A, US3735917A
InventorsWarburton R T
Original AssigneeMobil Oil
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Egg carton construction
US 3735917 A
A disposable carton formed of low cost material and adapted for the packaging of eggs and the like is formed with coacting elements of a cover and latching flap which, in combination, afford rigidity to those elements, guide the coacting elements on closure and provide for a secure latching susceptible of easy opening. Recesses are provided in cover and latching flap for guidance and rigidity. Latching is accomplished by a recess extending inwardly from the cover front wall to engage the underside of a latching bar of the flap, which is positioned above a substantially rectangular shaped recess in the latching flap.
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Description  (OCR text may contain errors)

United States Patent [191 Warburton [451 May 29,1973

[ EGG CARTON CONSTRUCTION [75] Inventor: Richard T. Warburton, Canandaigua, NY.

[22] Filed: June 18, 1971 [21] Appl. No.: 154,373

Related U.S. Application Data' [63] Continuation-impart of Ser. No. 137,915, April 27,

UNITED STATES PATENTS 3,207,409 9/1965 Reifers ..229/2.5

3,459,360 8/1969 Bagay ..229/45X 3 ,259,294 7/1966 3,465,947 9/1969 3,215,326 11/1965 Despres ..229/45X Primary Examiner-Donald F. Norton Attorney-Oswald G. Hayes, Andrew L. Gaboriault and James D. Tierney 5 7 ABSTRACT A disposable carton formed of low cost material and adapted for the packaging of eggs and the like is formed with coacting elements of a cover and latching flap which, in combination, afford rigidity to those elements, guide the coacting elements on closure and provide for a secure latching susceptible of easy opening. Recesses are provided in cover and latching flap for guidance and rigidity. Latching is accomplished by a recess extending inwardly from the cover front wall to engage the underside of a latching bar of the flap, which is positioned above a substantially rectangular shaped recess in the latching flap.

13 Claims, 9 Drawing Figures atented May 29, 1973 3,735,917

2 Sheets-Sheet l INVENTOR.

Patented May 29, 1973 2 Sheets-Sheet 2 INVENTOR. R/chard TWO/OUIIGfi EGG CARTON CONSTRUCTION CROSS REFERENCE TO RELATED APPLICATIONS The presentapplication is a continuation-in-part application of U. S. Pat. application Ser. No. 137,915, filed Apr. 27, 1971.

Copending U. S. application Ser. No. 15,108, filed Feb. 27, 1970 relates to egg carton structures.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is concerned with disposable cartons for packaging such merchandise as eggs and characteristically comprises a bottom tray portion formed to provide cells for the packaged goods, a top cover portion hinged to the rear of the tray and a latching flap hinged to the front of the tray. The latching flap is adapted to coact with the cover for retention of the closure. More particularly, the invention concerns the novel structure of the cover and latching flap to assure proper alignment on closing by automatic closure machinery and to afford rigidity to the elements; all in combination with a novel detent, i.e. inwardly projecting recess, and latching bar integrally formed with the cover and flap.

2. Description of the Prior Art Egg cartons of this general type have been common for many years. An early type is shown by Cox US. Pat. No. 2,517,465 in which the latching flap is exterior of the cover and provided with tabs insertable into slots in the front face of the cover. Cartons of the same general nature but having an inner latching element are shown by Schilling US. Pat. No. 2,600,130 in which the latching flap is extended to provide upper cells intended to afford greater protection to the packaged eggs. Schilling provides a friction type latch in which a protrusion in front of the flap engages a matching recess in the cover.

Many attempts have been made to improve on the Schilling carton by different specific configuration of latching mechanisms. Most of the subsequent development has eliminated the extension of the latching flap as an unnecessary precautionary structure, it being found that eggs supported in properly designed cells of the tray suffer little breakage during transit under any reasonable handling without the positive cell structure in an upper part of the carton.

For the most part, egg cartons are today filled and closed on automatic machinery which imposes certain restrictions on acceptable structures. A further restraint on acceptable structures is imposed by the characteristics of the material from which the carton is formed. Most such cartons are prepared on molding machinery from either wood pulp or thermoplastic material and the structure must be such that it can be formed from these inexpensive materials at high speed and readily stripped from the molds.

Each of the two types of material (pulp and thermoplastic) and the types of equipment on which these may be formed has its own idiosyncrasies to which the carton structure must accommodate.

Much of the effort toward design of molded egg cartons has been concerned with adaptation to molding machines, materials and techniques and to the demands of automatic filling and closing machinery.

A typical prior art improvement on the Schilling carton is shown by Reifers US. Pat. No. 2,990,094, provided with a latch having a protrusion on the outward face of the latching flap which enters into and engages the edge of a hole in the face of the cover. An outstanding character of this structure is that the protuberance of the flap extends downwardly when the carton is in extended position, as it exists in the mold, thus, facilitating formation of the protuberance in molding machinery. A sloping face of the cover makes it easy to strip from the mold a cover having a hole therethrough. It is a characteristic feature of the Reifers carton that the front surface of the cover has a high degree of flexibility necessary for proper latching and closure.

A somewhat different improvement of Schilling appears in Despres U.-S. Pat. No. 3,215,326 which utilizes a rigid front face of the cover and provides bridge elements in each of the cover and latching flap to engage in cavities of the other of these two coacting elements. A further modification of Schilling appears in Andrews US. Pat. No. 3,465,947 formed with re-entrant engaging surfaces on cover and flap to provide a positive latch of high security, but requiring special molding techniques to achieve the under-cuts in the elements. U. S. Pat. No. 3,539,092 to Dahlberg discloses a locking arrangement for cartons similar to the abovedescribed Despres patent.

SUMMARY OF THE INVENTION The improvement on Schillings structure, characterizing this invention, involves a combination of coacting elements in the front surface of the cover and in the latching flap capable of rapid and efficient formation on automatic molding machinery and affording significant advantages in filling, closing, shipping, marketing and household storage. The front of the cover and the latching flap are provided with a number of complementary recesses extending inwardly from the front of the carton and each defined by relatively flat recess surfaces connected to the front primary plane of each element (cover and flap) by webs essentially planar in nature and sloping sharply toward the recessed surface. This combination of webs and planes set at angles to each other provides a beam effect imparting a high degree of rigidity and strength to these elements. The nature of the recesses and the relatively great number employed, also act for guidance in closing of the carton as it contacts the closing members on automatic machinery. Such closing members tend to twist the elements engaged thereby, an effect counteracted by those complementary recesses, unobstructed by latches. As an additional assist to the aforedescribed guidance recesses, to insure positive engagement of the latching elements, the latching flap is characterized by the recess, which is located adjacent to and immediately below the latching bar of the flap, having a relatively large surface area, preferably rectangular in configuration. Such an enlarged recess insures that the relatively smaller inwardly projecting detent member on the front cover wall will seat properly in the latching flap latch recess, even though the carton closing operations may have twisted the latching elements out of proper alignment for positive latching. Such an arrangement substantially eliminates carton latching difficulties encountered as a result of the latching elements being provided in partial recesses but obstructed by latching elements which interfere with these recesses acting with full effectiveness for guidance purposes.

The inwardly projecting detent member on the front wall of the carton may assume a variety of configurations. For example, it may be substantially rectangular to conform symmetrically to the rectangular recess which it engages when the carton is in a closed and latched condition. The width dimension of such detent members must be sufficiently smaller than the width dimension of the rectangular locking flap recess to assure ease of entry of the detent and therefore proper locking engagement of the carton sections in the carton closed position. The symmetrical relationship of the rectangular recess in the flap member and the rectangular configuration of the inwardly projecting detent, although of a narrower dimension than that of the flap recess, offers the added advantage of assisting the complementary flap-cover wall guidance recesses in resisting forces applied to the ends of the carton which would otherwise result in lateral movement of the carton cover and cellular bottom sections with respect to one another.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are shown in the annexed drawings wherein FIGS. 1 and 2 are perspective views of one form of the carton in varying stages of closure;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a fragmentary view illustrating a form of the invention in which the latching mechanism is entirely shielded in the closed carton;

FIG. 5 is a sectional view taken along line 55 of FIG. 4;

FIGS. 6 and 7 are perspective views, similar to FIG. 1, showing other specific embodiments of the carton structures of the present invention;

FIG. 8, is a fragmentary view of a carton, similar to FIG. 4, showing still another embodiment of the cartons contemplated by the present invention;

FIG. 9 is a cross-sectional view of the carton section illustrated in FIG. 8 and taken on line 99 of FIG. 8.

DESCRIPTION OF PREFERRED EMBODIMENTS As shown in the drawings, the carton is constituted by a bottom tray portion 1, a cover 2, and a latching flap 3. The tray portion is formed to provide a plurality of cells 4 for reception of eggs and the like molded integrally with dividing surfaces and an upper flange 5 which may lie wholly in one plane. The cover 2 is formed integrally with the tray 1 and connected thereto by a portion of reduced thickness 6 constituting a hinge.

Similarly, the latching flap 3 is formed integrally with "the tray 1 and connected thereto by a line of reduced thickness 7 constituting a resilient hinge.

As formed in a mold, the three portions of the carton are in their greatest extended position such that the flange 8 of the cover lies in the same plane as flange 5 of the tray and the latching flap 3 lies extended out to the other side of the carton as formed. This imparts to the hinges 6 and 7 a bias toward extended position.

With particular reference to the cover 2, this is constituted by an upper surface 9 which, in the embodiment shown, is essentially planar except for a recess 10, essentially as shown. Molded integrally with the top surface 9 are side walls 11, a back wall 12 and a front wall 13. Formed in the front wall are recesses constituted by depressed surfaces 14 and webs 15 of a structure such as to impart to the front wall a high degree of strength and rigidity capable of supporting burdens of cartons stacked one above another and of maintaining alignment of the front surface for efficient action of the latching mechanism also characteristic of this invention. The latch elements of the cover are constituted by detents 16 formed of recessed surfaces and webs similar to those of the guiding elements, but terminating in a free edge 17.

Formed in the latching flap are recesses constituted by recessed surfaces 18 and webs l9 complementary to the recesses in the cover. It will be noted that the cover recesses and those flap recesses employed for guidance of the cover into locked engagement with the flap are wedge shaped and complementary in form. This structure assures that these guidance elements shall become engaged after cover is rotated into closed position and that as the flanges 5 and 8 approach contact, the complementary recesses fit snugly together and assure positive latch engagement.

The latching element of the latching flap is constituted by a rectangular recess which is shorter in extent, than those which impart strength and guidance. A recessed surface 20 is connected to the main body of the flap by webs 21. The essentially rectangular shaped recess terminates short of the upper edge of the flap to provide a latching bar 22 above the recess. Upon rotation of the cover to close position, the relatively small detent l6 enters into the relatively larger rectangular recess bounded by webs 21 and detent edge 17 engages the latching bar 22. This manner of closure is more fully illustrated in FIGS. 1, 2 and 3 showing how the rigid face of the cover presses the latching flap rearward against its resilient hinge until the latch elements are engaged, as in FIG. 3.

The embodiment shown in FIGS. 1 through 3 is characterized by a recess in the latching elements of the cover fully extending to the upper surface of the cover. These are readily formed by molding elements similar to those which form the guidance recesses. The detent is readily formed by cutting from such a recess a rectangular portion of the structure indicated generally at 23. This embodiment of the invention is readily formed on automatic thermoforming machinery followed by a cutting operation. I

An embodiment quite different in appearance, but identical in coaction of its elements, is illustrated in FIGS. 4 and 5 wherein the recess to provide detent 16 is not continuous to the top of the cover. By comparison of FIGS. 2 and 3 it will be seen that the only difference is that the latch is covered in the embodiment of FIGS. 4 and 5 when the carton is closed. A carton of this latter type is preferably formed by a thermoforming operation which molds the guidance and rigidity recesses followed by an operation of cutting a slit 24 in the face of the cover and depressing a portion below that slit to form the detent.

The embodiment of the egg carton structure illustrated in FIG. 6 is substantially the same as the carton structure illustrated in FIGS. 1 and 2, however, in the case of the carton shown in FIG. 6, detent member 16' is substantially rectangular in shape as contrasted to the wedge-shaped detent configuration of the carton illustrated in FIGS. 1 and 2. It will be noted that the rectangular configuration of the detent member 16 conforms substantially to the rectangular recess 20 of the carton locking flap. As hereinbefore disclosed, when the carton is in a closed and locked position, mating rectangular recesses and 16 assist in preventing lateral shifting of the carton cover section and bottom section during the handling of such cartons.

The carton illustrated in FIG. 7 is substantially identical to the carton of FIG. 6, however, it will be noted that the recess in the front wall of the carton cover above aperture 23 has a substantially rectangular configuration, i.e., the side walls of the recessare substantially parallel.

In still another embodiment of the carton structures of the present invention, as illustrated in FIG. 8, it will be noted that recess 27, located in the front wall of the carton above slit 24, tapers inwardly from the plane of the cover front wall so that the edge of recess 27 at the point immediately above slit 24 is substantially in the same plane as the front wall of the carton cover and progressively tapers inwardly from slit 24 to the top wall of the carton cover. Such an arrangement allows for individual cartons to be nested, one within the other, during storage or shipment thereof, more readily than the carton illustrated in FIG. 4.

In all of the embodiments of the carton latching mechanism hereinabove disclosed, although the embodiments may differ somewhat in their appearance, the coaction of the individual latching elements is identical.

To provide'stability of the carton when set on a flat surface, it is preferred that the bottom outward portion of the cells 4 be provided with feet 26.

Among some of the types of plastic materials which are suitable for fabrication into the carton structures of the present invention are polyolefins such as polyethylene, polypropylene, and polybutene; polystyrene; high impact polystyrene; polyurethane; polyvinylchloride and others. A particular material which has been found to be well suited for fabrication of the present carton structures is foamed polystyrene. The closed cell structure of the foamed polystyrene is a material which rapidly, reaches equilibrium with atmospheric moisture and therefore exerts no drying effect. The foam material itself is extremely light weight permitting ease of handling and transport.

As hereinbefore indicated, a preferred material employed in the formation of the carton structures of the present invention is plastic and in particular foam thermoplastic materials and especially polystyrene foam. The polystyrene foam may be' manufactured utilizing any one of the number of conventional extrusion techniques, for example, extrusion of foamable polystyrene beads, i.e., beads which have a blowing agent already incorporated in them prior to delivery to an extrusion apparatus or, for example, by direct injection extrusion techniques wherein a foaming agent is added to a molten mass of polystyrene contained within an extruder prior to extrusion thereof from a die orifice. See. U. S. Pat. No. 3,444,283, Carlson.

After the polystyrene foam sheet material has been produced utilizing conventional extrusion techniques as discussed above, it may be molded to form the carton structures of the present invention. In general, it is desirable to preheat the formed polystyrene sheet before it is molded in order to assure that the sheet will be at a sufficiently elevated temperature to permit rapid forming of the desired structure in the mold.

After preheating the formed polystyrene foam sheet, the cartons of the present invention may be conveniently formed utilizing a molding operation such as match molding, for example.

The process employed for forming the cartons may best be understood by a description of a specific embodiment as illustrated in the following example, how ever, such a description is solely for purposes of illustration and is not to be construed in a limiting sense. For example, the following embodiment sets forth rather specific process and operating conditions employed when preformed polystyrene foam is employed as the starting material for the structure and, of course, such conditions will normally vary when other plastic materials are employed.

EXAMPLE l A preformed sheet of polystyrene foam material with an average density of about 7 pounds per cubic ft. and approximately mils thick was fed into a radiant preheat oven and heated to a temperature of approximately 225F. Upon emerging from the preheat oven, the polystyrene sheet was approximately 200 mils thick as a result of the expanding action of the residual blowing agent, in this case pentane, which remains entrapped within the polystyrene cells after it is extruded. The residence time of the polystyrene-in the oven was approximately 5 to 20 seconds and the average line speed was about 15 ft. per minute. Immediately upon emergence from the preheat oven, the polystyrene foam sheet passes into a forming mold. The thermoforming mold employed is essentially a temperature controlled female mold maintained at about F. and a lower male forming member maintained at a temperature of about 100F. As the match mold is cycled, the upper and lower mold members are brought together forcing the heated polystyrene foam to assume the configuration of the mold members.

The shape of the molds and of the freshly molded carton is essentially that shown in FIG. 1 except that rectangular opening 23 has not been cut. As formed, the cover and flap in extended position as would appear on rotation of elements in FIG. 1 is as follows: the cover is rotated to the left to a position in which flange 8 lies in the same plane as flange 5 and the flap is rotated to the right until it also lies in that same plane.

Rectangular opening 23 is formed by a second operation in which the carton cover 2 is supported against a surface having a suitable die orifice and the openings 23 are cut out by punches.

In an alternative type of operation, the openings 23 may be formed in the mold by providing reciprocating elements in the female part of the mold which punch out the opening. Similar elements are used to form the embodiment shown in FIGS. 4 and 5. It will be immediately apparent that a female mold of fixed configuration which will form the recessed surfaces and webs of detent 16 would have a portion overlying that part of the front wall of the cover immediately above the detent 16.

Alternatively to forming the detent 16 in the embodiments of FIGS. 4 and 5 by a separately moving element in the mold, the freshly formed carton without such detent may be transferred to a second stage at which the slit 24 is cut and a heated element of suitable shape pressed against the carton to depress a portion under the slit, forming the detent 16.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

I claim:

1. In a carton adapted for the packaging of eggs and the like having 1. a bottom tray formed to define a plurality of cells for reception of packaged articles and of a depth such that said articles are enclosed thereby for a portion less that their vertical dimension as packaged,

2. a cover resiliently hinged to the rear upper edge of said tray and having side and end walls fixed to each other and to a top for said cover, all of such dimensions that the packaged articles are substantially enclosed when the edges of said tray, said front wall lying primarily in a plane sloping inwardly toward said top, and

3. a latching flap hinged to the front upper edge of said tray by resilient means biasing said flap toward a position outward of vertical from said front edge; said cover and said flap having coacting means associated therewith capable of engagement upon closure of the carton in a manner to maintain such closure;

the improvement which comprises a cover and latching flap to afford i. rigidity of flap and front wall of cover,

ii. guidance in closure for assurance of proper seating when closed, and

iii. positive engagement of latching elements; said configuration being characterized by:

a. at least one recess in said front wall defined by a wedge portion extending to and tapering outwardly toward the top of said cover and spaced inwardly from the primary plane of said wall, and rigidity-imparting webs connecting said wedge portion with the main body of said front wall lying in said primary plane,

b. at least one inwardly projecting detent in said front wall terminated by an edge intermediate said top and the lower edge of said front wall, and at least one recess in said flap complementary to said recess in said front wall and similarly defined by wedge portion and rigidity imparting webs whereby the cover is guided on closure, and

. at least one recess in said flap, said recess having a substantially rectangular configuration, terminated short of the upper edge of said flap by a latching bar extending along said edge and positioned in the primary plane of said flap arranged and adapted for contact with said detent on closure to depress the flap against resilience of its hinge and for engagement of said detent upon completion of closure.

2. A carton according to claim 1 having said detent formed by removal of a section of said wedge portion.

3. A carton according to claim 1 having said front wall of the cover continuous and lying in the primary plane thereof above said detent.

4. A carton according to claim 1 having a plurality of said recesses spaced along the front wall of said cover.

5. A carton according to claim 1 constituted of a foamed thermoplastic resin.

6. A carton according to claim 1 constituted of foamed polystyrene.

7. A carton according to claim 1 having three said recesses spaced along the front wall of said cover.

8. A carton according to claim 4 having said detent spaced between two of said recesses.

9. A carton according to claim 8 having three said recesses and two said detents.

10. A carton according to claim 9 constituted of foamed polystyrene.

11. A carton according to claim 1 wherein said inwardly projecting detent has a substantially rectangular configuration.

12. A carton according to claim 1 wherein the portion of said front cover wall above said detent is recessed inwardly.

13. A carton according to claim 12 wherein said inwardly recessed portion above said detent is substantially rectangular.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3207409 *Sep 4, 1962Sep 21, 1965Diamond Int CorpMolded pulp egg carton
US3215326 *Nov 20, 1963Nov 2, 1965Keyes Fibre CoMolded pulp carton latch
US3259294 *Jan 17, 1964Jul 5, 1966Skandinavisk Emballage AktieseMoulded pulp packing and method for producing same
US3459360 *Feb 12, 1968Aug 5, 1969Keyes Fibre CoLocking means for carton covers
US3465947 *Mar 5, 1968Sep 9, 1969British Petroleum CoContainers
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4612153 *Jul 12, 1984Sep 16, 1986Mobil Oil CorporationProcess and apparatus for thermoforming a thermoplastic carton having an aperture therein for latching the cover
US4625905 *Feb 20, 1986Dec 2, 1986Mobil Oil CorporationHinged cover carton
US4742953 *Sep 17, 1986May 10, 1988Mobil Oil CorporationHinged cover carton with inboard locking extensions
US7255231Dec 31, 2003Aug 14, 2007Pactiv CorporationEgg carton
US8991604 *Jan 11, 2012Mar 31, 2015Brødrene Hartmann A/SEgg package
US20050145529 *Dec 31, 2003Jul 7, 2005Andrews Alan P.Egg carton
US20140042169 *Jan 11, 2012Feb 13, 2014Brødrene Hartmann A/SEgg Package
WO2005065215A2 *Dec 22, 2004Jul 21, 2005Andrews Alan PEgg carton
U.S. Classification206/521.1
International ClassificationB65D85/30, B65D85/32
Cooperative ClassificationB65D85/324
European ClassificationB65D85/32D