GB2128962A - Moulded carton locking system - Google Patents

Abstract

A locking system used with a moulded carton e.g. for eggs has a lock flange 13 moulded in the upwardly projecting direction and attached to the base 11 of the carton and a protrusion 16 on the lock flange 13 which fits into an opening 17 in a cover 12. For additional engagement security, an indent 21 on the lower lip of the opening 17 engages the bottom surface 22 of the protrusion 16. A creased hinge line 23 joins the lock flange 13 and base 11 and compressive pressure exerted by abutments 40 maintains an engaging force of the protrusion 16 with the opening 17 through which it extends. <IMAGE>

Description

SPECIFICATION Moulded carton locking system This invention relates to cartons and more particularly to a locking system to maintain an egg carton in a closed position during handling and storage.

Egg cartons in prior art utilize locking devices to prevent spillage of eggs from the carton during handling of the cartons. These have been used on cartons of different materials including molded pulp material, paperboard, and various forms of molded plastic.

Locking systems utilizing beak-shaped locks are known in molded cartons wherein a beakshaped protrustion, projecting upwardly from the base, enters an opening or recess or the like on a side of the cover to hold the cover shut until the beak is pushed inward to release it from the cover. Structures of this type are shown in USP's 3,217,963; 3,276,656; 3,459,360; 3,469,764; 3,471,078; 3,531,039; 3,570,747; 3,572,578; 3,672,560; 3,672,693; and 3,749,235.

Without denigrating the prior structures, it should be noted that they, in general, do not provide sufficient egg protection from vertical forces because of the absence of a bracing flange. In addition, due to molding requirements, the "beak" has usually been so located that the material below the mating opening in the front wall of the cover easily tears. These prior cartons have not, in general, been formed with bracing flanges because of the difficulty in molding such a structure.

A further problem with a fixed male "beak" lock, is the need to target the location of the cover edge closely to the beak locking face, in order to effect easy and secure closure. Failure to properly target such locks may interfere with the requirements of automation handling.

The lock form of the present invention is operated like the familiar button lock of the prior art and is therefore easy and natural for consumers to use. It incorporates a minimally rotatable bracing flange to support the locking lugs.

This lock form may be used with a variety of different package configurations holding the different numbers of eggs of these configurations and operates with existing automation equipment used with all these configurations.

The lock form having an upright molded locking and bracing flange saves space during its manufacture and lowers costs. It saves space on the molding machine thus allowing more productivity per machine hour, and its construction permits it to be easily molded. It also saves space on erecting equipment which may be important on larger sizes near a critical fit.

Reliability of this new lock form is improved since the new lock is part of the nested portion and is less subject to damage than prior art extended forms. The bracing flange also helps to protect the carton from vertical compression which would cause egg breakage.

The lock form of the present invention produces more secure locking because of its greater tendency to remain engaged than extensively prefolded hinged locks of the prior art.

The lock of the present invention includes a lock flange which is molded upright as an extension of the natural nesting wall angle of the carton and can be mechanically pre-folded inwardly to establish the proper operational locking angle.

Unlike the famous molded button-lock cartons commonly in use today wherein the locking flat is molded in the same plane as the open carton, whereby in use the flap is rotated more than 90 to fit inside the carton cover. in the present carton the flange hinge is of a character which permits rotation of the upright molded flange only a maximum of about 40 , preferably not more than about 35'.

The connected web forming a bellows foldable connection of the new lock to the cell base, differs from prior art in its initially upright molded position-also in the fact that the new flap is only free to rotate inwardly through a bending range up to 40 from its initially molded position. Unlike prior art, the lock cannot be folded outward without destroying its function.

This limited movement is enough to insure that the lock can be moved to target to the cover during automation closure, overcoming the lack of targeting of the beak-type lock.

The lock flange in an embodiment of the present invention includes a protrusion or lug thereon engaging with a protrusion on the bottom edge of the lock opening for greater lock engagement and security.

The lock flange of the present invention also includes a hinge assembly with an area of reduced thickness which also interacts with the front cover wall.

The lock of an embodiment of the present invention also has further advantages of additional stacking strength, i.e. bracing, due to engagement of the top edge of the locking flange and cover.

In the lock of the present invention, abutment forms come into action as the lock flange is bent inward, forcing a stop to rotation of the lock flange and insuring continuing lock projection through the cover lock openings.

These as well as further advantages which are inherent in the invention will become more apparent from the following description, reference being had to the accompanying drawings wherein: Figure 1 is a side elevation of an egg carton embodying the lock of the present invention showing the carton in a wide open position; Figure 2 is a partial perspective enlarged view of the lock flap portion of Fig. 1 viewed from the outside of the carton; Figure 3 is a partial perspective further enlarged view of the lock flap portion of Figs.

1 and 2 viewed from the inside of the carton; Figure 4 is a section view of the lock flange of Fig. 3 along line IV-IV; Figure 5 is a reduced size, in comparison to Fig. 2, partial perspective view of a portion of the cover which fits over the lock flange of Figs. 1-4 as viewed from the outside of the cover of Fig. 1; Figure 6 is a partial sectioned view along lines VI-VI of Figs. 2 and 5 with the cover over the lock flange; Figures 7A-7B show the compression effect that forms a bellows fold in the thinned area of the lock structure; Figures 7C-7D show an alternative lock form in which the "thin bellows" area is not present-the lock rotation inward terminates when the lock flap shoulders contact the cell shoulders; Figure 8 is a sectional view of another embodiment showing the interrelationship between the locking elements; and Figure 9 is a partial perspective view of the front cover, showing the locking opening, in the embodiment of Fig. 8.

Referring first to Fig. 1, there is shown a side elevation of a molded carton 10 using the lock form of the present invention. In the illustrated case an egg carton is shown, although the lock form is not necessarily limited in its use to only egg cartons. Egg carton 10 has a base 11 with cover 1 2 attached hingedly to one longitudinal edge and a lock flange 1 3 along the opposite longitudinal edge in a position to lock cover 1 2 in a closed position.

As shown in more detail in Fig. 2, 3 and 6, lock flange 1 3 is hingedly connected to base 11. In the open position of Fig. 1, carton 10 is in the position for nesting of other cartons 10 within it. The upright molded lock flange 1 3 may optionally have an offset 1 5 along its top edge to aid in nesting of vertical flange sections 13.

Lock flange 1 3 has lock protrusions 1 6 along the top edge of lock flange 1 3 to coincide with lock openings 1 7 in cover 1 2 as shown in Figs. 5 and 6. Beneath each lock protrustion 1 6 on the lock flange 1 3 is a vertical depression 38' which serves to increase the depth of the horizontal bottom surface 22 of the lock protrustion 1 6.

One of the means of obtaining more secure locking of the cover 1 2 to lock flange 1 3 is illustrated in the shape of indent 21 in the bottom lip of lock opening 17. Indent 21 extends inwardly under bottom surface 22 of lock protrusion 1 6 and allows the cover 1 2 a better hold on lock protrustion 16.

When top cover 1 2 is closed downwardly on lock flange 13, lock flange 1 3 which has been in a substantially upright position must bend inwardly along a hinge line 23 and must only partially return when lock protrusion 1 6 passes into lock opening 1 7. To accomplish this smoothly, lock flange 1 3 must have sufficient flexibility to bend along hinge line 23 but must also have enough return force to keep all lock protrusions 1 6 extending into, and securely remaining in respective openings 17. Several hinge line formations that can produce this result are illustrated in Figs. 2, 4, 6 and 7A-7D.

Fig. 4 shows a cross-section through a lock flange 33 and hinge line 34 showing a thinned area 35 that slants inwardly of the carton 10 toward its top edge. This thinned area extends over lock flange indent designated by dimension line 36 in Fig. 3. Fig. 3 shows the rear of lock flange 33.

As the lock flange 33 is folded inwardly, scoring or bending is controlled by the thin area along dimension lines 37 which thin area is basically in tension along hinge line 34.

The thin material along dimension line 36 goes into compression as the lock flange indent tip 38, which constitutes the opposite side of the vertical depression 38', swings in, until indent tip 38 and the lower edge of the flange 13, connected at line 36, come to rest (see Fig. 2) against cylindrical abutment forms 40 at the top of the base 11 under the lock flange 33. Thus, the bottom outside edge of the flange 33 defines a scalloped edge 45 which, as the upper part of the flange 33 rotates inwardly becomes forced against the abutment forms 40, the latter acting as a flexible stop which, due to the memory of the material from which the carton is formed, creates a spring return action on the flange resisting further inward movement and driving the flange outwardly. This restricts the amount of fold angle possible for the lock, thus insuring that the lock will stay in a tight relationship with maximum projection of lock protrusion 16 through lock openings 17.

In Fig. 6 a similar bending action and return force takes place upon closing of the cover. In this case a crease is formed along hinge line 23.

Figs. 7A-7B schematically show the folding action of the preferred lock form. Here the hinge line is molded as a thin web 43 which folds like a bellows upon inward movement of the lock flange thus helping to create the return locking force. The resistance of making this bellows fold combines with the abutment of forms 40 to help insure lock return force.

Figs. 7C-7D schematically show alternative forms wherein wherein there is no hinge at all, i.e. instead, there is a gap 42, along the area corresponding to line 36 in Fig. 3.

Figs. 8 and 9 illustrate a variant of the locking elements, wherein the wall 52 of the front cover extending immediately above the locking opening extends in a plane spaced inwardly from the remainder of the front wall of the cover portion, so that the bottom forming edge 51 of such locking opening is spaced outwardly compared to the upper edge 53 of the opening. In addition, the vertical dimension, i.e. the height of the opening is reduced and as best seen in Fig. 8, the height of the locking lug 56 is greater than the height of the locking opening.

As the lock becomes engaged in the embodiment of Figs. 8 and 9, edge 51 deflects outwardly as it is pushed over the lug 56, and edge 53 falls behind the lug 56 to prevent inadvertent inward movement thereof. This variant therefore provides a double-acting lock, the engagement of the edge 51 with the bottom of the locking lug, in combination with the hinge urging the bracing flange in the forward direction, providing a first locking action; and the engagement of the back of the lug 56 with the lower part of the wall 52 providing a second locking effect. To effect opening of the carton, the edge 51 must be lifted over the locking lug 56, a motion most customers find natural.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.

Claims (6)

1. A locking system for a molded carton such as for an egg carton comprising a base of the carton, a cover hingedly connected to the said base, a lock flange attached to the opposite edge of said base from said cover and projecting upwardly at all times, a hinge portion along the juncture of said base and flange, a lock protrusion on said lock flange, a lock opening in said cover positioned to receive said lock protrusion, means to produce a force on said lock flange to keep said lock protrusion engaged in said lock opening, said force including a compressive force.

2. The locking system of Claim 1, wherein said means to produce a force comprises a crease on a hinge line connecting said lock flange to said base.

3. The locking system of Claim 1, wherein said means to produce a force comprises a web on a hinge line connecting said lock flange to said base and foldable into a bellows shape.

4. The locking system of Claim 1, further characterized by said lock opening having an indent on the lower lip of said lock engaging with said lock protrustion.

5. The locking system of Claim 1, further characterized by the front wall of the cover having a wall extending upwardly from the lock opening, said wall being spaced inwardly of the remainder of the front wall of said cover so that said wall above the opening is recessed, the height of the opening being less than the height of said lock protrusion, whereby when the carton is locked the upper part of the lock protrusion extends above and in front of the bottom of said recessed wall above the lock opening.

6. A moulded carton locking system substantially as herein described with reference to and as shown in the accompanying drawings.