US2718999A

US2718999A - Self-locking folding box construction

Info

Publication number: US2718999A
Application number: US280791A
Authority: US
Inventors: Frederick E Helmick
Original assignee: Baljak Corp
Current assignee: Baljak Corp
Priority date: 1952-04-05
Filing date: 1952-04-05
Publication date: 1955-09-27
Anticipated expiration: 1972-09-27

Description

Sept- 1955 F. E. HELMICK SELF-LOCKING FOLDING BOX CONSTRUCTION 2 Sheets-Sheet 1 Filed April 5, 1952 INVENTOR. Fr'eaer/ck E A's/mick Sept. 27, 1955 F. E. HELMICZK 2,718,999

SELF-LOCKING FOLDING BOX CONSTRUCTION Filed April 5, 1952 2 Sheets-Sheet 2 INVENTOR. Frederick E. Helm/ck 4M ATTORNEY United States Patent SELF-LOCKING FOLDING BOX CONSTRUCTION Frederick E. Helmick, Belmont, Califi, assignor, by mesue assignments, to Balj'ak Corporation, Wilmington, DeL, a corporation of Delaware Application April 5, 1952', Serial No. 280,7 9-1 4 Claims. (Cl. 229-35),

This invention relates to improvements. in cartons, boxes, trays, or other structures: made from blanks of cardboard, paperboard. or other suitable, fold'able sheet material hereinafter collectively referred to as boxes,

folding boxes.

More particularly, the invention applies-to gluel'esslyassembled folding boxes in which the box corners arelocked by means of a lock flap articulated to one wall panel and inserted into a cut in another wall panel which extends from the body of the other wall panel into a top flap articulated to the other wall panel along-a top: fold line.

Box corner constructions of this general type are favored for the packaging of frozen foods, and the corner lock is quite secure if the box is closed.

The folding of the top flap tends to close the locking cut tightly, since in the locked and closed box the locking cut extends from one panel into another panel lying at an angle thereto, and the lock flap which extends through the cut is locked in position firstly by frictional engage-- ment at the tightly closed cut, and secondly a locking tip on the lock flap is bent into an angular position with respect to the remainder of the lock flap by the folding of the top flap, and thus prevents the lock flap from being withdrawn from the cut.

Locks of the aforementioned type are satisfactory and secure as long as the top fla-pssometimes also referred to as dust flaps in the box artare folded. However, all previous corner constructions of this type, as far as I' am aware, have the disadvantage of being quite unreliable prior to the folding of the top flaps, particularly during the period of filling of the box with contents. In the case of frozen food boxes which are filled on automatic machinery, and especially in the case of boxes into which the contents are tightly packed, accidental opening of a corner lock amounts to a serious disturbance of the packaging procedure, since the box" in question must be removed f'rom the automatic machine. Frequently, the failing box jams before itsremoval, or otherwise disturbs the functioning of the machine. This requires temporary stopping of a whole line of machinery which generally comprises a box forming machine, a box filling machine, a box closing machine, and finally a box wrapping machine, allinterconnected by a common drive for synchronized operation.

The present invention provides an improvedcornerconstruction of the aforementioned type which is secure against accidental opening of the box corner from the time the box leaves the box forming machine. More particularly, the improved lock does not depend on the fold-- valuable in frozen food boxesdue to the inevitable-expamsion ofthe box contentsduring freezing-.

The reliability of the improved lock makesthe improved corner construction particularly suited for: handling on automatic filling and closing machinery, and it eliminates the previously experienced disturbances due to accidental opening of the box corners.

These and other features, objects and advantages-of the invention will appear more fully from the detailed description which follows, accompanied by drawings showing, for the purpose of illustration, a preferred embodiment of the invention.

The invention also consists in new and improved details of construction hereinafter set forth and claimed.

Although the characteristic features of the invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

Fig. 1 is a plan view of a flat box blank embodying the invention, the inside surface of the blank facing the observer;

Fig. 2 is a perspective View of the box blank of Fig. l in the process of assembly, but prior to the completion of the corner locks;

Fig. 3' is: a perspective view of the box shown in Fig. 2 after completion of the corner locks, but prior to folding of the top flaps, the box being ready for filling;

Fig. 4 is a perspective view of the box of Fig. 3 with thecorners locked and secured by folding of the top flaps; and

Fig. 5 is a perspective view of the inside. of the view being taken in the direction of arrow 5 in Fig. 4.

in the following description and in the claims, various. structural details will be identified by specific names for convenience. The names, however, are intended to be as generic. in their application as the art will permit. Corresponding reference characters refer to corresponding, parts in the several figures, of the drawings.

In the drawings accompanying, and forming part of; this specification, certain specific disclosure of the invention is; made for the purpose of explanation of broader aspects of the invention, but it is understood that the details may be modified in various respects without departure' from the: principles of, the invention and that the invention may be applied to other structures than the one shown.

The blank A. shown in Figure 1 may be cut and scored, inmultiple, from a large sheet or roll of paperboard or other suitable foldablematerial on an automatic cutting and? scoring machine. Only one sideof the blank need be decoratively finished or imprinted, since only one side of the blank is presented as the outside of the finished, box. If the box is to be: used for the packaging of frozen foods, waxed, or otherwise moisture-proofed stock is'used.

The blank. A is sub-divided by several scored. fold lines toprovide a main or bottom panel 11 to which side wall panels; 12 and 13 are articulated along

side fold lines

14 and 15. Front and

back panels

16 and 17 are ar-ticu latedto. the bottom panel 11 along foldlines 18 and- 19, respectively.

Lock flaps

20, 21, 22 and 23 are articulated to. the front and

back panels

16 and 17, respectively, along side fold.

lines

24, 25, 26 and 27, respectively. These side foldlines, are either aligned with, or slightly offset with respect to, thefold

lines

14 and 15 to compensate for the thickness, of the board, in a conventional manner.

Corner fl'aps

28, 29, 3t and 31 are articulated to the side wall panels 12' and 13, respectively, along

side fold lines

32, 33, 34 and 35-.

Top flaps

36 and 37 are articulated to the side wall panels 12 and 13- along

top fold lines

38 and 39, respect-ively.

A-cover panel 40 is articulated to the back panel: 11

.2 along a fold line 4-1 and a cover flap 42 extends hingedly from the cover panel along a fold line 43. The cover flap 42 has a two-pronged lock tab 44- of more or less conventional configuration for engagement with a tab locking cut 45 in the front panel 16.

The improved corner locks of the box blank comprise internal cuts of bent outline in the side wall panels and in the associated top flaps which engage lock tips on the respective lock flaps. In the illustrated embodiment the construction of all four box corners is alike and it will therefore be suflicient to describe one of the four

cuts

46, 47, 48 and 49, and one of the associated

lock tips

50, 51, 52 and 53.

The internal cut 47 is of bent outline and comprises a first portion 54 within the body of the side wall panel 12. The first portion extends to the top fold line and thence the cut continues into the body of the top flap 36, the continuing portion of the cut being numbered 55. It will be noted that the cut portion 55 extends at an angle with regard to the portion 54, and also forms an angle on with regard to the top fold line 38. An end portion 56 of the cut extends at an angle with respect to portion 55 and is preferably substantially parallel to the top fold line 355. The distance, or mean distance, of the end portion 56 from the top fold line 38 is indicated as h.

The internal cut 47 forms an internal tongue 53 in the side wall 12 and in the top flap 36. This internal tongue extends towards the adjacent box corner and is relatively easily deflected with regard to the remainder of the blank, as long as the wall panel 12 and its flap 36 lie in the same plane. It is evident, however, that this tongue will become rigid and inflexible when the flap 36 is bent with respect to the wall panel 12, as will later appear.

The internal tongues formed by

internal cuts

46, 48 and 49 are numbered 57, 59 and 69, respectively.

A lock tip 51 extends from the lock flap 22 for engagement with the internal cut 47. The lock tip may be a part of the panel proper of the lock flap 22, but is preferably articulated thereto along a tip fold line 61. The height of the tip above the fold line 61, or above the continuing edge 62 of the lock flap 22 is indicated as H and is greater than the distance h previously mentioned. These dimensions are based on the condition that the height of the

side wall panels

12 and 13 is substantially equal to the height of the front and

back wall panels

16 and 17, except for allowances for board thickness to facilitate folding.

The size relation may also be expressed in terms of distance from the respective fold lines which define the main panel 11. If so considered, the distance of the point of the lock tip 51 from the fold line 19, or its con tinuation, is greater than the distance of the end portion 56 of the internal cut from the fold line 14. The reasons for these particular dimensions will become apparent from a consideration of the assembly procedure.

The

lock tips

50, 52 and 53 may be articulated to their

respective flaps

20, 21 and 23 along

fold lines

63, 64 and 65, and the dimension of these tips with regard to their

respective cuts

46, 48 and 49 is the same as previously described in connection with the tip 51.

The formation of a box from the blank A may proceed as follows:

The corner flaps 28, 29, 3t} and 31 are first folded relatively to the

side wall panels

12 and 13 into substantially upright position. The

side wall panels

12 and 13 are then folded upright with respect to the bottom panel 11 along

fold lines

14 and 15. Substantially simultaneously, or shortly thereafter, the front and

back panels

16 and 17 are folded upright with respect to the bottom panel 11 along

fold lines

18 and 19, and the lock flaps 20, 21, 22 and 23 are folded into a position substantially parallel with the folded

side wall panels

12 and 13. The

internal tongues

57, 58, 59 and 60 are flexed towards the outside, causing the cuts to open so that the lock flaps 20, 21, 22 and 23 may enter between the outside surface of the side wall panels and the inside surface of the flexed tongues.

The resulting box structure is shown in Fig. 2. It will be noted that the four box corners are formed, but that they are not completely locked since the lock tips still lie on the outside of the respective top flaps. This is seen particularly well at 52 and 53.

As the next operation, the lock tips are pulled to the inside of the box. This is done by grasping either the lock tip at its base or by grasping the respective lock flap below the base of the lock tip and pulling it to the inside of the box until the lock tip snaps past the end portion 56 of the internal cut.

This operation is preferably performed by automatic machinery basically consisting of a plunger which forces the flat blank through a correspondingly shaped die. During the passage of the blank through the die the internal tongues are flexed outwardly, and the same mechanism which performs the flexing then grasps the lock flap or the lock tip which slides under it and pulls the tip towards the inside of the box. A preferred form of apparatus for this purpose is disclosed in the patent of John Pagendarm, No. 2,580,189, of December 25, 1951.

Fig. 3 illustrates the box with the corners locked, in the condition in which the box is discharged from the box forming mechanism disclosed in the Pagendarm patent. The box is now ready for filling. Its corners will not unlock, even if contents are packed in the box body with a certain amount of compression. The security of the lock is due to the fact that the lock tips extend beyond the confines of the internal cuts and thus cannot be withdrawn from the cuts without tearing of the board. The caliper of the board, as well as the grade of the board, is, of course, selected to withstand the stress to which the box is subjected during the normal handling by the box machinery, particularly by the filling machine.

The corner flaps 28, 29, 30 and 31 rest firmly against the adjacent front and back panels. They seal the corners sufficiently tight to permit A of water to stand in the box for hours without leaking.

After the box is filled, the top flaps 36 and 37 are folded into a position substantially parallel to the bottom panel 11 and the box cover is then closed and locked. Folding of the

top flaps

36 and 37 with respect to the

side walls

12 and 13 transforms the previously flat internal tongues into three-dimensional structures of angular cross-sections. In this process the portions of the internal tongues tend to return into the plane of the panels from which they were cut and a pinching action results at the point of entry of the lock flaps 20, 21, 22 and 23 into the respective cuts.

In addition, the

lock tips

50, 51, 52 and 53 are bent at right angles with respect to the lock flaps from which they extend. This is shown on an enlarged scale in the perspective Fig. 5 in which the lock tip 51 is shown bent along the crease line 61 with respect to the lock flap 22. The lock tip 51 underlies the top flap 36, and it is evident that even substantial pressure against the back wall panel 17 will not cause the tip 51 to dislodge from its proper position. If subsequently the box is opened, and the top flaps are folded upward into substantially the same plane as the

side walls

12 and 13, the lock is still secure, since the tips will either remain in their bent position or, even if folded fiat with the respective lock flap, they will still prevent unlocking of the box corner since the height H is greater than the available space h through which they would have to slip out.

The invention thus provides an improved corner construction of great strength which eliminates the difiiculties previously experienced with corner locks which tended to open prior to the folding of the top flaps.

What is claimed is:

1. A glueless corner construction for folding boxes fold line, said first wall panel having an internal cut of bent outline therein extending across said top fold line and forming a tongue from the stock of said first wall panel and said flap, said tongue pointing towards the box corner; a lock flap articulated to the side edge of said second Wall panel and folded into a position parallel with said first wall panel, said lock flap extending through said internal cut into a position partially inside said one wall panel, said lock flap having a tip thereon bordered by a locking edge engaging said out in the top flap in corner locking position, the distance from said top fold line to said tip being greater than the distance from the top fold line to the end of the cut in said top flap, said tip being forceable against the resistance of the stock from which it is formed from a position outside said top flap through said out into a position inside said top flap, thereby providing a secure lock even before folding of said top flap.

2. A glueless corner construction for folding boxes comprising, a main panel, a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line intersecting said first fold line at an angle, said panels being folded about said fold lines with respect to one another into a position in whichthey form a box corner, a top flap articulated to said first wall panel along a top fold line substantially parallel to said first fold line, said first wall panel having an internal cut of bent outline therein extending across said top fold line at an acute angle and into said top flap, the end portion of the out within said top flap being substantially parallel to said top fold line, said internal cut forming a tongue from the stock of both said first wall panel and said flap, said tongue pointing towards the box corner; a lock flap articulated to the side edge of said second wall panel and folded into a position parallel with said first wall panel, said lock flap extending through said internal cut into a position partially inside said one wall panel, said lock flap having a tip thereon bordered by a locking edge engaging said cut in the top flap in corner locking position, the distance from said top fold line to said tip being greater than the distance from said top fold line to the said parallel cut portion, said tip being forceable against the resistance of the stock from which it is formed from a position outside said top flap through said cut into a position inside said top flap, thereby providing a secure lock even before folding of said top flap.

3. A glueless corner construction for folding boxes comprising, a main panel, a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line intersecting said first fold line at an angle, said panels being foldable about said fold lines with respect to one another into a position in which they form a box corner, a top flap articulated to said first wall panel along a top fold line substantially parallel to said first fold line, said first wall panel having an internal cut of bent outline therein extending across said top fold line and forming a tongue from the stock of said first wall panel and said flap, said tongue pointing towards the box corner; a lock flap articulated to the side edge of said second wall panel and foldable into a position parallel with said one wall panel, said lock flap being insertable through said internal cut into a position partially inside said first wall panel; and a lock tip articulated to said lock flap along a tip fold line substantially parallel to said second fold line and in substantial registry with said top fold line when the panels are in corner forming position, the distance from said tip fold line to the end of the tip being greater than the distance from the top fold line to the end of the cut in the top flap, said tip being forceable against the resistance of the stock from which it is formed from a position outside said top flap through said out into a position inside said top flap, thereby providing a secure lock of the corner even before folding of the top flap and of the tip about their respective fold lines.

4. A glueless corner construction for folding boxes comprising, a main panel, a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line intersecting said first fold line at an angle, said panels being foldable about said fold lines with respect to one another into a position in which they form a box corner, a top flap articulated to said first wall panel along a top fold line substantially parallel to said first fold line, said first wall panel having an internal cut of bent outline therein extending across said top fold line at an acute angle and into said top flap, the end portion of the out within said top flap being substantially parallel to said top fold line, said internal cut forming a tongue from the stock of both said first wall panel and said flap, said tongue pointing towards the box corner; a lock flap articulated to the side edge of said second wall panel and foldable into a position parallel with said first wall panel, said lock flap being insertable through said internal cut into a position partially inside said one wall panel, and a lock tip articulated to said lock flap along a tip fold line substantially parallel to said second fold line and in substantial registry with said top fold line when the panels are in corner forming position, the distance from said tip fold line to the end of the tip being greater than the distance from the top fold line to said parallel cut portion, said tip being forceable against the resistance of the stock from which it is formed from a position outside said top flap through said cut into a position inside said top flap, thereby providing a secure lock of the corner even before folding of the top flap and of the tip about their respective fold lines.

References Cited in the file of this patent UNITED STATES PATENTS Re. 12,217 Webb May 3, 1904 1,592,374 Lytle July 13, 1926 2,536,384 Meller Jan. 2, 1951 2,553,870 Samsing May 22, 1951 2,617,580 Meller Nov. 11, 1952 FOREIGN PATENTS 555,273 France Mar. 19, 1923