US3361327A - Locking closure for a container and blank therefor - Google Patents

Description

LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFOR 2 Sheets-Sheet 1 Filed Aug. 11. 1965 INVENTOR 7 QObEF-YT L. WALDROP ATTORNEY- R; L. WALVDROP Jan. 2, 1968 LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFOR Filed Aug. 11, 1965 2 Sheets-Sheet ,2

. INVENTOR ROBERT L. WALDROP ATTORNEY5 United States Patent C) 3,361,327 LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFOR Robert L. Waldrop, Bon Air, Va., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed Aug. 11, 1965, Ser. No. 478,835 13 Claims. (Cl. 229-38) ABSTRACT OF THE DISCLOSURE This disclosure relates to a locking top closure for a container wherein such top closure is formed by folding extension flaps provided in adjoining vertical walls inwardly and substantially into a common plane. The locking closure has an outer flap which is folded and locked in position last and such locking closure is foolproof in that irrespective of the sequence used in folding the inner extension flaps in position a positive locking closure is always provided.

This invention pertains to an improved container closure and more particularly to a foolproof container locking closure and to an improved blank for making such container closure or the like.

Many of the containers, such as food containers, in current use, are opened to obtain access to the product carried therein by opening an exterior wall, such as the entire top thereof, and then reclosed to protect any remaining product. Such current containers generally are diflicult to re-close positively, while others have expensively produced closures, and still others will only provide closure by following procedures usually too inconvenient to be followed.

Accordingly, it is a feature of this invention to provide a closure for a container which is inexpensively and efiiciently produced without requiring special machinery.

Another feature of this invention is to provide means for easily opening a container by tearing away a portion of an exterior wall thereof while providing a positive closure for such exterior wall which is closable in a foolproof manner.

Another feature of this invention is to provide a foolproof locking closure for a container having an open top wherein the top is formed by cooperating extension flaps in a plurality of oppositely arranged side Walls forming such container and one of said extension flaps is defined as an outer flap provided with suitable projections therein and identification means on the outer side thereof, the projections assuring that it will intermesh with the remaining flaps to form said top while the identification means assuring it is the final flap to be closed.

Another feature of this invention is to provide score means in such outer flap to thereby provide greater flexibility therefor, and to assure easier cooperation with the extension flap means.

Therefore, it is an object of this invention to provide an improved container having one or more of the novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved container blank for such a container or the like.

Other objects, uses, and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIGURE 1 is a perspective view illustrating a container having the foolproof locking closure of this in- 3,361,327 Patented Jan. 2, 1968 vention and showing a sealing flap holding such container sealed prior to its initial opening.

FIGURE 2 is a perspective view of the upper portion of such container with the extension flaps forming the top thereof extended vertically and with the sealing flap torn away and held immediately above its tear line.

FIGURE 3 is a perspective View of the upper portion of such container showing the first step in one of the several possible foolproof ways of sequentially closing the extension flaps forming the top wall and illustrating the closure of a side wall flap first prior to closing the end wall flaps.

FIGURE 4 is a perspective view of the upper portion of such container illustrating the second step in which the end flaps are folded overlapping the side wall flap and showing the outer flap in its vertical position.

FIGURE 5 is a perspective view of the upper portion of such container showing the third step in which the outer extension flap is being inserted into centrally located elongated slit means defined by the other extension flaps in their folded positions.

FIGURE 6 is a perspective view of the upper portion of such container showing the outer flap in its closed position and the top of the container positively reclosed.

FIGURE 7 is a plan view of an improved container blank used to make the container of FIGURE 1 particularly showing the foolproof locking closure of this invention and showing the center portion of such blank broken away.

While the various features of this invention are hereinafter illustrated and described as being particularly adaptable for providing a reclosure for the top wall of a food container, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide foolproof reclosures for other walls and for any variety of articles that may be carried within such container.

Therefore, this invention is not to be limited to only the embodiments illustrated in the drawings because the drawings are merely utilized to illustrate one of the Wide variety of uses of this invention.

In the exemplary embodiment of the invention illustrated in FIGURE 1, a container 20 is provided having a sealed top which utilizes the foolproof locking closure of this invention.

Container 20 is initially opened, in this example, by tearing away an integral sealing strip in the top thereof permitting extension flaps in the vertical walls and forming such top to be folded outwardly for access to the food product therein. Container 20 may then be reclosed easily in a foolproof manner in that irrespective of the order of folding such extension flaps inwardly to form the container top the closure of this invention provides positive locking therefor.

Container 20 has side wall means shown as a plurality of six foldably connected Walls 21, 22, 23, 24, 25 and 26 which are preferably made from a single sheet of foldable material. Walls 21, 22, 23 and 24 have extension flap means extending therefrom and cooperating together to close the top of said container 20, illustrated as top wall 26.

An extension flap 34B and 31 extends from oppositely arranged end walls 21 and 22 respectively, while an extension flap 32 extends from first side wall 23 and extension flap 33 extends from oppositely arranged second side wall 24.

Each end wall extension flap 30 and 31 has its base defined by a score line 34 and 35 respectively at the top edge of associated walls 21 and 22, and the extension flap is the same width as its associated end wall.

The area of extension flap 30 is defined by a rectangular portion 33A and a right triangular portion 30B, each portion 30A and 3tlB lying with one of their sides along the base of extension flap 30, Le, along score line 34, and another of their sides adjoining on a common line. Right triangular portion 30B has its hypotenuse extending between one terminal end of the extension flap base and a point illustrated at 33 along the adjoining side common to right triangular portion 30B and rectangular portion 30A. Point 38 is generally along the middle portion of that side of area 30A which forms a part of the adjoining side. 7 Similarly the area of extension flap 31 is defined by a rectangular portion 31A and a right triangular portion 31B each lying with one of their sides along the base of flap 31 and another of their sides adjoining. Right triangular pOrtion 31B has its hypotenuse extending between the terminal end of its extension flap base, opposite a corresponding end in fiap 30, and a point illustrated at 39 along the adjoining side common to portions 31A and 31B.

The terminal end areas of each flap 30 and 31 extending outwardly beyond points 38 and 39 are generally rectangular in shape and provide support for outer flap 33.

Extension flap 32 in side wall 23 has its base defined by a score line 36 at the upper end of wall 23 and is generally coextensive in width with the width of side wall 23. Flap 32 has a generally rectangular cut-out illustrated at 37 at its terminal end and defined by U-shaped cut 58 in such flap.

It will be seen in FIGURES 3-6 that extension flaps 30, 31, and 32 are adapted for folding inwardly to define a centrally located elongated slit means or slot 40 in the container. The length of slot 49 is defined by the Width of the central portion of U-shaped out line 58. Furthermore, it will be apparent from the drawings that the length or extension of flap 32 from its base to its central outer edge as defined by the center portion of cut 58 is smaller than the height of each triangular portion normal to its respective adjoining side. This dimensioning defines the width of slot 40.

Extension flap 33 in side wall 24 is of generally rectangular configuration, and has its base defined by a score line 41 at the upper end of wall 24 while being generally coextensive in width with side Wall 24. Flap 33 has cut means or slits 42 defining a generally rectangular tear-off portion 43, used in this example as a sealing flap, coextensive with flap 33 and having a generally centrally located trapezoidal cut-out in one side thereof shown at 44. The wider parallel side of the trapezoidal cut-out in flap 33 coincides with the tear edge defined by slit portions 42A and 42B of slit means 42, such that upon tearing ofif sealing flap 43 a centrally located trapezoidal extension 45 is provided at the terminal end of the rectangular outer extension flap 33.

It will be seen therefore that the remaining area of flap 33 is defined by a generally trapezoidal portion 46 (see FIGURE 7 showing the container blank) flanked at either side by a pair of right triangular tab portions 47 and 48. Tab portions 47 and 48 are of equal height which is less than the height of trapezoidal portion 46 such that trapezoidal extension 45 extends outwardly beyond tabs 47 and 48.

Tab portions 47 and 48 are defined by symmetrically arranged score means or lines 47A and 48A respectively in outer fiap 33.

Score lines 47A and 48A are defined by extending each nonparallel side of the trapezoidal extension 45 inwardly to the end of the outer extension flap base (score line 41) adjacent thereto. Score lines 47A and 48A provide greater flexibility for the outer flap 33 during insertion of the trapezoidal extension 45 in slot 40.

To assure that flap 33 is folded last upon closing top 26, identification means, such as color coding, writing, or application of metal foil or the like is placed on the outer surface of flap 33. A user will realize immediately that flap 33 is the last one to be folded inwardly.

FIGURES 36 illustrate the various steps in one of the possible ways of folding extension flaps 30-33 to provide a positive foolproof closure for container 20. FIGURE 3 shows flap 32 folded inwardly first, followed by flaps 30 and 31 (FIGURE 4) and finally (FIGURE 5) outer flap 33 is folded inwardly showing the outer trapezoidal extension being inserted in slot 40.

Another way of folding the various extension flaps to reclose container 26 would be to fold flap 30 in position first, followed in succession by flaps 32, 31, and finally with flap 33. Similarly flap 31 may be folded in position first followed by fiaps 32, 30, and 33 in the order stated.

Still another way of reclosing the top wall of container 20 is to fold flaps 3t and 31 in position followed by flap 32 and then outer flap 33.

From the unique construction of the flaps 31, 32, 33, and 34 and their cooperation irrespective of the way in which they are sequentially overlapped to form top 26, it will be apparent that a foolproof closure is provided which provides a positive locking closure for container 20.

Sealing flap 43 keeps outer flap 33 in position and top 26 closed prior to initially opening container 20. Flap 43 is fastened to container 29 by suitable fastening means, for example glue or the like, associating only with flap 43. Upon tearing off sealing flap 43 the remaining flaps provide the positive locking closure as previously described.

While in the exemplary embodiment of the invention the sealing strip 43 is integral with flap 33 prior to being torn 01f, it will be appreciated that a container could be provided in which the sealing flap is separate.

Container 20 can be made in any suitable manner and made from any suitable foldable material. Itis preferably formed from the container blank 50, illustrated in FIGURE 7. Blank 50 is made of cardboard or the like having a side such as the exposed surface thereof laminated with metallic foil, such as aluminum-containing metallic foil, or the like, suitably colored, embossed, imprinted or remaining plain as desired.

Blank 50, in this example, is suitably cut and scored to define six foldably connected walls shown as walls 21, 22, 23, 24, 25, and 26. Walls 23, 21, 24, and 22 are defined and foldably interconnected by a series of parallel score lines 52, 53, 54 and 55.

Score means shown as score lines 34, 35, 36, and 41 in blank 50 define extension flaps 30, 31, 32, and 33, extending from walls 21, 22, 23, and 24 respectively. Each extension flap 30, 31, 32, and 33 is foldable about its base which is the same width as its associated wall and coincides with score lines 34, 35, 36, and 41 respectively.

Suitable cut and/or score means is provided in each extension flap defining its specific structural configuration as will be subsequently described, such configuration providing locking means. It will be seen that irrespective of the sequence of closing each extension flap upon assembling container 20 from blank 50, the top 26 of container 20 formed by such extension flaps is positively closed upon finally closing outer flap 33.

The foolproof locking closure for reclosing container 20 is provided after tearing away the sealing strip portion 43.

Walls 21 and 22 are designated as end walls in the assembled container having extension flaps 30 and 31 as previously mentioned. Extension flap 3% has its base'defined by score line 34 and its area defined by a rectangular portion 30A and a right triangular portion 308 lying with one of their sides along score line 34 and another of their sides adjoining. One side of rectangular portion 30A is defined by slit line 56 in blank 50'. The right triangular portion has its hypotenuse extending between one ter minal end of the extension flap base defined by fold line 34 and a point illustrated at 38 along the middle portion of a side of the rectangular portion 30A, which side coincides with the adjoining side. Similarly extension flap 31 has an area defined by a similar corresponding rectangular portion 31A and triangular portion 31B having one side along score line 35. One side of rectangular portion 31A is defined by a slit line 57 in blank 50 simi lar to slit line 56. The hypotenuse of portion 31B extends between a corresponding terminal end of score line 35 and point 39. It will be seen, therefore, that the remaining terminal end of each end wall extension flap 30 and 31 is generally rectangular in shape.

Score means defined as a score line 36 is provided in side wall 23 defining extension flap 32 coextensive therewith and extending therebeyond. Extension flap 32 has its base coinciding with score line 36.

A generally U-shaped cut 58 in the terminal end of extension flap 32 defines a rectangular cut-out therein and shown at 37. U-shaped cut 58 is dimensioned to assure proper cooperation with associated extension flaps. The outward extension of fiap 32 from its base 36 to its central outer edge defined by the center portion of U- shaped cut 58 is smaller than the height of each triangular portion 30B and 318 normal to its respective adjoining side.

The dimensioning and structural arrangement thus described assures that upon forming container 20 and folding flap 32 and flaps 30 and 31 inwardly to form a portion of top 26 an elongated slot 40 is defined having a width defined by cooperating flaps 30, 31, and 32 and a general length defined by the central portion of the U- shaped cut.

Score means defined as a score line 41 is provided at the upper end of side wall 24 and along with slit lines 56 and 57 define the inner portion of a generally rectangular extension flap coextensive therewith and extending beyond score line 41. The base of extension flap 33 coincides with score line 41 along its full length.

Cut means shown as slit line 42 having side slits 42A and 42B is provided in flap 33 defining a generally rectangular tear-off sealing strip portion 43 coextensive in width with the outer flap 33. Sealing strip 43 has a generally centrally located cut-out in one side thereof defined by slit line 42 and having the general shape of a trapezoid. The cut-out is centrally arranged along one edge of strip 43 with its wider parallel side thereof coinciding with the tear edge illustrated at 42A and 4213 at opposite sides of strip 43. It will be seen that upon tearing ofi? tear-off strip 43 a centrally located trapezoidal extension tongue 45 is provided at the terminal end of extension flap 33.

Upon assembling container 20 from blank 55 sealing strip 43 is torn away to open such container and the outer flap 33 assures, upon being finally closed, that irrespective of the inward folding sequence of the end wall and side wall extension flaps that the trapezoidal extension 45 will be inserted in the slot 40 to positively lock and close container 20.

Flap 33 has a pair of triangular portions 47 and 48 defined by score lines 47A and 48A respectively in the outer corners of the rectangular portion of the outer flap 33. Such triangular portions assure that top 26 of container 20 is positively closed.

Score lines 47A and 48A in flap 33 lie along lines defined by extending each nonparallel side of the trapezoidal extension 45 inwardly toward the end of the base of extension flap 33, which is defined by fold line 41, which is adjacent thereto.

Blank 50 has a closing tab 60 at one end thereof extending beyond score line 52. Score line 52 also defines one side of side wall 23 as previously mentioned.

In addition, as particularly illustrated in FIGURE 7, each wall 21, 22, 23, and 24 has a bottom forming flap at its opposite end defined by score lines 61, 62, 63, and 64 respectively in each wall and a series of parallel slits 6 65, 66, and 67 in blank 5! The bottom flaps cooperate to define the bottom 25 of the container 20 once blank 50 is folded to form a container. Closing tab 60' is fastened to side wall 22 along one of its sides by any suitable means such as glue or the like.

The terms bottom, or top wall, top, end wall, and side wall have been utilized in this description and the appended claims merely to define the position of the walls as shown in the drawings. It is to be understood, however, that the container as shown could be oriented in any manner.

Thus, it is seen that an inexpensive foolproof locking closure is provided for reclosing a container top after initially opening such top by tearing away a portion thereof which is integral with one of a plurality of extension fiaps which fold into a common plane to define such top. It will be seen that irrespective of the order of folding such extension flaps a positive locking closure is provided. Further, this invention provides an improved container blank for forming such container and closure or the like.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be used, all coming within the scope of the claims which follow.

What is claimed is:

1. A foolproof locking closure for reclosing a container after opening an exterior wall thereof comprising side wall means, extension flap means including an outer flap extending from said side wall means, a tear-off portion in the terminal end of said outer flap cooperating with said extension flap means to initially keep said container closed, said extension flap means cooperating with the remaining portion of said outer flap to close said exterior wall after the initial opening thereof, and locking means in said extension flap means cooperating with said outer flap such that irrespective of the sequence of closing said flap means a positive closure is provided for said container upon finally closing said outer flap.

2. A container locking closure as set forth in claim 1 including fastening means provided for association only with said tear-off portion to keep said container closed initially.

3. A foolproof locking closure for reclosing a container after opening an exterior wall thereof comprising, a plurality of side walls, extension flap means extending from said side walls and cooperating to close said exterior wall, with one of said extension flap means defining an outer extension flap, a tear-0i portion in the terminal end of said outer flap cooperating initially with said extension flap means to initially keep said container closed, said extension fiap means cooperating with the remaining portion of said outer flap to close said exterior wall after the initial opening thereof, and locking means in said exten sion fiap means cooperating with said outer flap such that irrespective of the sequence of closing said flap means a positive closure is provided for said container upon finally closing said outer flap.

4. A container locking closure as set forth in claim 3 comprising, cut means in said outer extension fiap defining said tear-off portion, said tear-off portion being of generally rectangular configuration and coextensive in width with said outer flap and having a generally centrally located trapezoidal cut-out in one side thereof with the wider parallel side of said trapezoidal cut-out coinciding with the tear edge of said rectangular tear-off portion, and fastening means provided for association only with said tear-off portion to keep said container closed initially.

5. A foolproof locking closure for reclosing a container top comprising, a pair of oppositely arranged end walls, an extension flap extending from each end wall and each having its base of the same width as its associated end Wall and having an area defined by a rectangular and a right triangular portion each lying with one of their sides adjoining, said triangular portion having its hypotetop.

nuse extendingbetween one terminal end of said base'and a point along said adjoining side, first and second oppositely arranged side walls, an extension flap in said first side Wall having-its base the same width as said first side wall and having a rectangular cut-out at it terminal end defined by a U-shaped cut therein, said extension flaps being adapted for folding inwardly to define centrally located elongated slit means, a generally rectangular extension flap in said second side wall having its base coextensive therewith and defining an outer extension flap, and cut means in said outer extension flap defining a generally rectangular tear-otf portion coextensive in'width with said outer flap and having a generally centrally located trapezoidal cut-out in one side thereof with the wider parallel side of said trapezoidal cut-out coinciding with the tear edge of said rectangular tear-off portion, such that upon tearing off said tear-off portion a centrally located trapezoidal extension is provided at the terminal end of said rectangular outer extension flap, said outer flap assuring upon being finally closed that irrespective of the inward folding sequence of said end wall and first side wall-extension flaps said trapezoidal extension is inserted in said slit means to reclose said container and the outer corners of said rectangular portion of said outer flap assure positive locking for said top.

6. A container locking closure as set forth in'claim includingfastening means provided for association with said tear-off portion to keep said container closed initially.

7. A container locking closure as set forth in claim 5 in which said outer fiap further comprises symmetrically arranged score means in the rectangular portion thereof along lines defined by extending each non-parallel side of said trapezoidal extension to the end of said outer extension flap base adjacent thereto, said score means providing greater flexibility for said outer flap during insertion of said trapezoidal extension in said slit means, and identification means on the outer surface of said outer flap assuring that it will be the final one to be folded to close said 8. A foolproof locking closure for reclosing a container top, said container being made from a singlesheet of foldable material comprising, a pair of oppositely arranged end walls, an extension flap extending from each end wall and each having its base of the same width as its associated end wall and having an area defined by a rectangular and a right triangular portion each lying with one of their sides adjoining, said triangular portion having its hypotenuse extending between one terminal end of said base and a point along said adjoining side, first and second oppositely arranged side Walls, an extension flap in said first side wall having its base the same width as said first side wall and having a U-shaped cut in its terminal end defining a generally rectangular cut-out, said extension flaps being adapted for folding inwardly to define centrally located elongate-d slit means, a generally rectangular extension flap in said second side Wall having its base coextensive therewith and defining an outer extension fiap, cut means in said outer extension flap defining a generally rectangular tear-off sealing flap portion coextensive in width with said outer flap and having a generally centrally located trapezoidal cut-out in one side thereof with the wider parallel side of said trapezoidal cut-out coinciding with the tear edge of said sealing flap, such that upon tearing off said sealing flap a centrally located trapezoidal extension tongue is provided at the terminal end of said rectangular outer extension flap, symmetrically arranged score means in said outer flap, and fastening means provided for association with said tear-off sealing flap portion to keep said container closed initially, whereby upon tearing away said sealing flap the remaining portion of said outer flap assures, upon being finally closed, that irrespective of the inward folding sequence of said end wall and first side wall extension flaps said trapezoidal extension is inserted in said slit means to reclose said container and the outer corners of saidv rect-angular portion of said outer wall assurepositive looking for said top while said score means provide flexibility, for easy insertion in said slit means.

9. A container blank being cut and scored to define a container having a top which is initially opened by tearing away a portion thereof and which has a foolproof locking closure for reclosing said top, said blank defining six foldably connected exterior Walls including a pair of end walls and first and second side Walls, score means in each end wall defining an extension flap therebeyond each extension flap having its base coinciding with said score means and of the same width as its associated end wall and having an area defined by a rectangular and a right triangular portion lying with one of their sides adjoining,

said right triangular portion having its hypotenuse extending between one terminal end of said base and a point along the middle portion of a side ofsaid rectangular portion which coincides with said adjoining side such that the terminal end of each end wall extension flap is gen-- erally rectangular, score means in said first side wall defining an extension flap coextensive therewith and extending therebeyond and having its base coinciding with said first side wall score means, a generally U-shaped cut in the terminal end of said'first side wall extension flap defining a rectangular cut-out at its terminal end, said extension flaps being adapted for folding inwardly to define centrally locate-d elongated slit means, score means in said second side wall defining a generally rectangular extension flap coextensive therewith and extending therebeyond and having its base coinciding with said second side wall score means, and cut means in said outer extension flap defining a generally rectangular tear-off sealing strip portion coextensive in width with said outer flap and having a generally centrally located trapezoidal cut-out in one side thereof, with the wider parallel side of said trapezoidal cut-out coinciding with the tear edge of said rectangular tear-off portion, such that upon tearing off said tearoif portion a centrally located trapezoidal extension tongue tongue is provided at the terminal end of said rectangular outer extension flap, whereby upon assembling said container from said blank said sealing strip is torn away to open said container top and said outer flap assures upon being finally closed that irrespective of the inward folding sequence of said end wall and first side wall extension flaps said trapezoidal extension is inserted in said slit means to reclose said container and the outer corners of said rectangular portion of said outer flap assure positive locking for said top. 7

10. A container blank is set forth in claim 9 in which said outer fiap includes symmetrically arranged score means in the outer rectangular portion thereof along lines defined by extending each nonparallel side of said trapezoidal extension to the end of the base of said outer extension flap adjacent thereto.

11. A container having a foolproof locking closure defining its top wall means comprising, a pair of oppositely arranged end walls, an extension flap extending. from each end wall, first and second oppositely arranged side walls, a first approximately U-shaped extension flap extending from said first side wall and having a base portion and a pair of identical outwardly extending leg portions, said first extension flap being foldable inwardly with said extension fiaps extending from saidend walls to define top wall means having substantially centrally located elongated slit means provided therein and said first extension" having an area defined by a generally trapezoidal central portion flanked by a pair of substantially identical right triangular tab portions each having a height less than the height of said trapezoidaltportionto thus define a trape-' zoidal extension arranged outwardly of said right triangular tab portions, and eachtof said right triangular tab' portions has a base portion which partially overlaps an associated one of said leg portions to provide a positive locking of said top wall means upon finally folding said outer extension flap in position and inserting said trape zoidal extension in said slit means irrespective of the prior folding sequence of said end wall and first side wall extension flaps.

12. A container closure as set forth in claim 11 in which said outer extension flap further comprises symmetrically arranged score means therein defining the hypotenuse of each of said triangular tab portions to provide greater flexibility therefor and assure easier cooperation with said extension flaps arranged therebeneath to provide said positive closure for said container.

13. A container blank being cut and scored and adapted to be assembled together to define a resulting container having an integral foolproof locking closure defining its top wall means, said blank comprising, a pair of end walls adapted to be oppositely arranged in said resulting container, an extension flap extending from each of said end walls, first and second side Walls adapted to be oppositely arranged in said resulting container, a first approximately U-sl1aped extension flap extending from said first side wall and having a base portion and a pair of identical outwardly extending leg portions, said first extension flap being adapted to be folded inwardly with said extension flaps extending from said end walls in said resulting carton to define top wall means having substantially centrally located elongated slit means provided therein and said first extension flap having said leg portions arranged adjacent opposite ends of said slit means and extending therebeyond toward said second side wall,

and an outer extension flap extending from said second side wall, said outer extension flap having an area defined by a generally trapezoidal central portion flanked by a pair of substantially identical right triangular tab portions each having a height less than the height of said trapezoidal portion to thus define a trapezoidal extension arranged outwardly of said right triangular tab portions, and each of said right triangular tab portions has a base portion which in said resulting container partially overlaps an associated one of said leg portions to assure apositive locking of said top wall means upon finally folding said outer extension flap of said resulting container in position and inserting said trapezoidal extension in said slit means irrespective of the prior folding sequence of said end wall and first side wall extension flaps.

References Cited UNITED STATES PATENTS 2,034,594 3/1936 Norris et a1 229--39 2,186,109 1/1940 Hultin 22951 2,390,412 12/ 1945 Axsherg 229-51 2,661,143 1/1953 Inman 229-37 2,685,400 8/ 1954 MacArthur [229-51 3,258,192 6/1966 Kelty 22939 FOREIGN PATENTS 449,968 7/ 1936 Great Britain. 714,683 9/1954 Great Britain.

DAVIS T. MOORHEAD, Primary Examiner.

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