LOCKING MECHANISMS FOR EGG CARTONS
United States Patent 3568916
Locking mechanisms for egg cartons having an integrally hinged tray and cover. The locking mechanism includes a locking flange that extends inwardly from the bottom of the cover's front wall and engages the underside of a protruding lip on the carton's tray when the carton is closed, and a depending flange that extends downwardly and outwardly from the inner edge of the locking flange to flex the locking flange over the protruding lip and into locking position as the tray and cover are moved into closed position.
US Patent References:
Egg cartons
Snow et al. - August 1968 - 3398875
Container with cam-latching top
Greatman - June 1966 - 3258186
Carton with cam-latching lid
Greatman - June 1966 - 3258187
Egg carton
Makowski et al. - January 1967 - 3298594
Egg carton and label
Pearl et al. - August 1968 - 3396895
Egg cartons
Snow et al. - August 1968 - 3398875
Container with cam-latching top
Greatman - June 1966 - 3258186
Carton with cam-latching lid
Greatman - June 1966 - 3258187
Egg carton
Makowski et al. - January 1967 - 3298594
Egg carton and label
Pearl et al. - August 1968 - 3396895
Application Number:
04/813616
Publication Date:
03/09/1971
Filing Date:
04/04/1969
View Patent Images:
Export Citation:
Assignee:
Sinclair-Koppers Company (Pittsburgh, PA)
Primary Class:
Other Classes:
206/521.800
International Classes:
B65D43/16; B65D85/32; B65D85/30; B65D45/00
Field of Search:
229/2.5,44,29 (M)/ 229/45
Primary Examiner:
Moorhead, Davis T.
Claims:
I claim
1. A packaging carton comprising a bottom section having a front wall and a rear wall; a cover section having a front wall and a rear wall; laterally extending flanges on the upper and lower edges of the walls of the bottom and cover sections, respectively, said flanges being in substantial abutting engagement with one another when the sections are in closed position; interlocking means on the front walls of the cover and bottom sections for releasably holding the carton closed, said interlocking means comprising:
2. The carton of claim 1, in the form of an egg carton, with the bottom section having a plurality of egg-accommodating cells.
3. The carton of claim 1, wherein the carton is of unitary molded construction.
4. The carton of claim 3, wherein the carton is formed of foamed polystyrene.
5. The carton of claim 1, wherein a portion of said bottom section's front wall flange is raised to form the longitudinal locking lip, and a portion of said cover section's front wall flange extends downwardly and outwardly to form the leading edge of the depending flange.
6. The carton of claim 5, wherein the locking lip and locking flange of the interlocking means extend substantially along the entire front walls of the bottom and top sections intermediate their ends.
7. The carton of claim 1, including a plurality of spaced interlocking means along the front walls of the bottom and cover sections.
8. The carton of claim 7, wherein portions of the bottom section's front wall flange are raised and recessed forming a plurality of locking lips, and corresponding portions of the cover section's front wall flange extend downwardly to form the leading edges of the depending flanges.
9. The carton of claim 8, wherein the leading edges of the depending flanges and the laterally-extending flanges are substantially coplanar vertically.
1. A packaging carton comprising a bottom section having a front wall and a rear wall; a cover section having a front wall and a rear wall; laterally extending flanges on the upper and lower edges of the walls of the bottom and cover sections, respectively, said flanges being in substantial abutting engagement with one another when the sections are in closed position; interlocking means on the front walls of the cover and bottom sections for releasably holding the carton closed, said interlocking means comprising:
2. The carton of claim 1, in the form of an egg carton, with the bottom section having a plurality of egg-accommodating cells.
3. The carton of claim 1, wherein the carton is of unitary molded construction.
4. The carton of claim 3, wherein the carton is formed of foamed polystyrene.
5. The carton of claim 1, wherein a portion of said bottom section's front wall flange is raised to form the longitudinal locking lip, and a portion of said cover section's front wall flange extends downwardly and outwardly to form the leading edge of the depending flange.
6. The carton of claim 5, wherein the locking lip and locking flange of the interlocking means extend substantially along the entire front walls of the bottom and top sections intermediate their ends.
7. The carton of claim 1, including a plurality of spaced interlocking means along the front walls of the bottom and cover sections.
8. The carton of claim 7, wherein portions of the bottom section's front wall flange are raised and recessed forming a plurality of locking lips, and corresponding portions of the cover section's front wall flange extend downwardly to form the leading edges of the depending flanges.
9. The carton of claim 8, wherein the leading edges of the depending flanges and the laterally-extending flanges are substantially coplanar vertically.
Description:
This invention relates to packaging cartons, and more particularly to new and improved locking mechanisms for molded egg cartons.
Molded cartons with various types of integrally molded locking mechanisms have been provided in the past for the packaging of eggs. Exemplary of one widely used type of locking mechanism provides a pair of lugs on the outer surface of a locking flap hingedly connected to the bottom tray of the carton that are matable with and extend through corresponding apertures in the front wall of the carton's lid to lock the lid to the tray.
Cartons utilizing this type of locking mechanism, however, have generally proven unsatisfactory to housewives and other users, because they are difficult to open and close. The lug-locking principle requires flexing of the carton's walls by the user during opening and closing to free the lugs from the apertures. Due to the inherent stiffness of the material used in the manufacture of such cartons, however, and the outward pressure of the packaged articles, it is difficult for the user to flex the structure sufficiently to allow clearance for easy opening and closing. Such difficulties, of course, are not only inconvenient to the user but render the carton and the packaged articles prone to be damaged during repeated opening and closing of the carton.
In accordance with the present invention, new and improved locking mechanisms are provided for a packaging carton in which the carton comprises a bottom section having a front wall and a rear wall; a cover section having a front wall and a rear wall; and a hinged connection between the cover and bottom sections' rear walls so that the cover can assume a closed-superimposed position with respect to the bottom section.
Interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. The interlocking means includes a longitudinal locking lip integral with and extending along at least a portion of the length of the top of the bottom section's front wall; a locking flange integral with and extending inwardly from and along a portion of the length of the bottom of the cover section's front wall adjacent the locking lip, the locking flange engaging the underside of the locking lip when the carton is closed to hold the sections together; and a depending flange integral with and extending downwardly and outwardly from the inner edge of the locking lip as the sections are moved into a closed position to flex the locking flange over the lip and into locking position.
Preferably, the packaging carton is an egg carton, and the carton and interlocking means are of unitary molded construction.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.
The accompanying drawings which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.
Of the drawings:
FIG. 1 is a fragmentary perspective view of the front of an egg carton in a partially open position and showing the locking mechanism of one embodiment of this invention;
FIG. 2 is a broken view in vertical section of the egg carton of FIG. 1 in an open position;
FIG. 3 is similar to FIG. 2 and shows a modification of the front wall of the carton's lid;
FIG. 4 is a fragmentary and enlarged view in vertical section of the front of the carton in FIG. 1 in a closed position;
FIG. 5 is a fragmentary perspective view of the front of an egg carton in a partially open position and showing another embodiment of the locking mechanism of this invention;
FIG. 6 is a broken view in vertical section of the egg carton of FIG. 5 in an open position; and
FIG. 7 is a fragmentary and enlarged view in vertical section of the front of the carton of FIG. 5 in a closed position.
Reference will now be made in detail to present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.
The packaging cartons illustrated in the drawings and contemplated for use with locking mechanisms of this invention are egg cartons having a cover section or lid 10 and a bottom section or tray 12. The cover and bottom sections' rear walls 14 and 16, respectively, are hingedly connected by an integral web 18. Bottom section 12 has a plurality of egg-accomodating cells 20 arranged in parallel rows. While the number and rows of cells may vary, the bottom section preferably consists of a dozen cells arranged in two parallel rows of six cells each.
A wide variety of materials may be used in the manufacture of the carton structures illustrated in the drawings. Molded paper pulp, pasteboard, plastic and the like, for example, may be used. A preferred material, however, is thermoplastic foam, such as, for example, foam polystyrene, or other polymers, such as polyethylene, polypropylene, polyvinylchloride, and the like. For purposes of illustration and as preferred embodiments, the drawings show egg cartons and locking mechanisms for the cartons of unitary construction produced by vacuum molding or match-molding techniques from a sheet of polystyrene foam.
In accordance with the invention, interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. The relationship between the interlocking means and the top and bottom sections of the carton, as shown in the drawings, will be used in the specification and claims for clarity, but it is to be understood that the interlocking means may be reversed with respect to the carton's sections without departing from the scope of this invention.
As embodied, the interlocking means includes a longitudinal locking lip 22 integral with and extending along at least a portion of the length of the top of bottom section's front wall 24, and a substantially horizontal locking flange 26 integral with and extending inwardly from and along a portion of the length of the bottom of the cover section's front wall 28 adjacent locking lip 22. The upper surface 30 of locking flange 26 engages the underside 32 of locking lip 22 when the carton is closed to lock the bottom and cover sections together.
A depending flange 34 integral with locking flange 26 extends downwardly and outwardly from the inner edge 36 of the locking flange to assist in the locking and unlocking of the locking mechanisms.
During closing of the cartons, the inner surface 38 of depending flange 34 engages the locking lip 22 and flexes locking flange 26 outwardly over the outer edge 40 of lip 22 until the flange is free to snap back into engagement with the underside of locking lip 22.
To open the container, the fingers are inserted between the bottom section's front wall 24 and depending flange 34, and the flange is pulled upwardly and outwardly to pull locking flange 26 out of engagement and over the outer edge 40 of locking lip 22.
As best shown in FIG. 1, there is provided an outwardly and laterally extending flange 42 that extends around the bottom of the cover section's rear wall, its sidewalls, and a portion of its front wall, and a corresponding flange 44 on the top of the bottom section's walls, the flanges 42 and 44 being in substantial flush load-bearing engagement when the carton is closed.
In accordance with one embodiment of this invention, and as shown in FIGS. 1--4, locking lip 22 and locking flange 26 of the interlocking means extend substantially along the entire front walls of the bottom and top sections. As best shown in FIG. 1, a portion of the bottom section's flange 44 is raised along the bottom section's front wall 24 intermediate its ends, and forms locking lip 22 of the interlocking means. Further, a portion of the cover section's flange 42 extends downwardly and outwardly along the section's front wall 28 and forms the leading edge 46 of the depending flange 34 of the interlocking means.
Thus, the upper surface 30 of locking flange 26 in this embodiment is above the plane of engagement between the cover and bottom sections' flanges 42 and 44, respectively, and approximately coplanar with locking lip 22 so that the flange snaps into engagement with the underside 32 of the lip during closing for more positive locking.
Preferably, and as best shown in FIG. 2, locking flange 26 and depending flange 34 are integrally molded with the cover section's front wall 28 from a single sheet of thermoplastic foam. A bulge 48 is thus provided in front wall 28 to permit flexing of locking flange 26, primarily around the juncture 50 between bulge 48 and front wall 28, over lip 22 during closing. Bulge 48 may be either rounded, as shown in FIG. 2, or of rectangular configuration, as shown in FIG. 3.
To effect a locking closure of the carton of FIGS. 1--4, cover section 10 is rotated about hinge 18 toward closing relationship with bottom section 12 and pressed downward until flanges 42 and 44 are in abutting engagement. As the carton is closing, locking flange 26 is flexed outwardly about juncture 50 by the inner surface 38 of depending flange 34 riding over the outer edge 40 of locking lip 22. When the carton is completely closed as shown in FIG. 4, locking flange 26 snaps back into engagement with the underside 32 of lip 22 to hold the sections together.
When it is desired to open the carton, flange 34 is grasped and pulled upwardly and outwardly. This results in locking flange 26 flexing about juncture 50 and being pulled out of engagement with locking lip 22.
In accordance with an alternative embodiment of this invention, and as shown in FIGS. 5--7, there is provided a plurality of intermittently spaced locking lips 22' and corresponding locking flanges 26' on the front walls of the carton similar to the single locking mechanism of the previous embodiment. As best shown in FIG. 5, the bottom section's flange 44 is raised and recessed at spaced intervals along the section's front wall intermediate its ends, and forms the plurality of locking lips 22' of the interlocking means. Similarly, the cover section's flange 42 includes a plurality of downwardly extending portions at spaced intervals along the section's front wall 28, and forms the leading edges 46' of the plurality of depending flanges 34' of the interlocking means. Between the plurality of spaced locking flanges and lips, the flanges 42 and 44 lie in abutting engagement with one another when the sections are in a closed-superimposed position.
Thus, the upper surface 30' of locking flanges 26' in this embodiment are above the plane of engagement between the cover and bottom sections' flanges 42 and 44, respectively, and are approximately coplanar with locking lips 22' so that they snap into engagement with the undersides 32' of lips 22' during closing for more positive locking.
Preferably, and as best shown in FIG. 6, locking flanges 26' and depending flanges 34' are integrally molded with the cover section's front wall 28 from a single sheet of thermoplastic foam. Hence, as in the previous embodiment, a bulge 48 is provided in front wall 28 to permit flexing of the locking flanges over the locking lips.
In this embodiment, and as best shown in FIG. 7, locking lips 22' are recessed so that the leading edges 46' of flanges 34' are substantially coplanar vertically with the leading edges of flanges 42 and 44. Hence, the locking mechanism of this embodiment does not project any singular element beyond the normal boundaries of the carton substantially preventing the carton from being accidentally opened during handling.
Locking of the carton is effected in a manner similar to the previous embodiment, cover section 10 being pressed down against bottom section 12 to cause locking flanges 26' to snap under and into engagement with their corresponding lips 22'.
To open the carton, the fingers are wedged between a number of flanges 34' and the bottom section's front wall 24, and the flanges are pulled upwardly and outwardly, pulling flanges 26' out of engagement with the locking lips.
To strengthen the interlocking means of this embodiment, locking flanges 26' and locking lips 22 are located adjacent the carton ribs 51 that form the egg-accommodating cells 20 in the carton.
It can be seen therefore that the bottom and cover sections of both embodiments can be easily, automatically, and positively locked together simply by moving the sections into closed position, and easily opened simply by pulling upwardly and outwardly on the interlocking means depending flange 34.
The integral web 18 connecting the rear walls 14 and 16 of the cover and bottom sections, respectively, of both embodiments is preferably doubly creased at 52 and 54 to provide a double hinge with a compressible midportion 56 between the creases that resiliently urges the cover and bottom sections apart so that locking flange 26 snaps tightly into engagement with the underside of the bottom section's protruding lip 22 when the carton is closed.
It is to be understood that the cartons described in the drawings and utilizing the locking mechanisms of this invention are preferred carton designs for eggs. The invention, however, is applicable to a variety of egg carton shapes and other similar cartons. An egg carton, for example, having three parallel rows of four egg-accommodating cells each could easily be used with the present locking mechanism.
The invention thus provides new and improved locking mechanisms for packaging cartons and particularly molded egg cartons. The locking mechanism facilitates the easy closing, positive locking, and easy opening of the cartons without the need for applying excessive pressure and without fear of damage to the cartons or their contents. Further, the locking mechanisms of this invention can be integrally molded with the egg carton from a single sheet of suitable material using conventional molding techniques.
The invention in its broader aspects is not limited to the specific details shown and described and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.
Molded cartons with various types of integrally molded locking mechanisms have been provided in the past for the packaging of eggs. Exemplary of one widely used type of locking mechanism provides a pair of lugs on the outer surface of a locking flap hingedly connected to the bottom tray of the carton that are matable with and extend through corresponding apertures in the front wall of the carton's lid to lock the lid to the tray.
Cartons utilizing this type of locking mechanism, however, have generally proven unsatisfactory to housewives and other users, because they are difficult to open and close. The lug-locking principle requires flexing of the carton's walls by the user during opening and closing to free the lugs from the apertures. Due to the inherent stiffness of the material used in the manufacture of such cartons, however, and the outward pressure of the packaged articles, it is difficult for the user to flex the structure sufficiently to allow clearance for easy opening and closing. Such difficulties, of course, are not only inconvenient to the user but render the carton and the packaged articles prone to be damaged during repeated opening and closing of the carton.
In accordance with the present invention, new and improved locking mechanisms are provided for a packaging carton in which the carton comprises a bottom section having a front wall and a rear wall; a cover section having a front wall and a rear wall; and a hinged connection between the cover and bottom sections' rear walls so that the cover can assume a closed-superimposed position with respect to the bottom section.
Interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. The interlocking means includes a longitudinal locking lip integral with and extending along at least a portion of the length of the top of the bottom section's front wall; a locking flange integral with and extending inwardly from and along a portion of the length of the bottom of the cover section's front wall adjacent the locking lip, the locking flange engaging the underside of the locking lip when the carton is closed to hold the sections together; and a depending flange integral with and extending downwardly and outwardly from the inner edge of the locking lip as the sections are moved into a closed position to flex the locking flange over the lip and into locking position.
Preferably, the packaging carton is an egg carton, and the carton and interlocking means are of unitary molded construction.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.
The accompanying drawings which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.
Of the drawings:
FIG. 1 is a fragmentary perspective view of the front of an egg carton in a partially open position and showing the locking mechanism of one embodiment of this invention;
FIG. 2 is a broken view in vertical section of the egg carton of FIG. 1 in an open position;
FIG. 3 is similar to FIG. 2 and shows a modification of the front wall of the carton's lid;
FIG. 4 is a fragmentary and enlarged view in vertical section of the front of the carton in FIG. 1 in a closed position;
FIG. 5 is a fragmentary perspective view of the front of an egg carton in a partially open position and showing another embodiment of the locking mechanism of this invention;
FIG. 6 is a broken view in vertical section of the egg carton of FIG. 5 in an open position; and
FIG. 7 is a fragmentary and enlarged view in vertical section of the front of the carton of FIG. 5 in a closed position.
Reference will now be made in detail to present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.
The packaging cartons illustrated in the drawings and contemplated for use with locking mechanisms of this invention are egg cartons having a cover section or lid 10 and a bottom section or tray 12. The cover and bottom sections' rear walls 14 and 16, respectively, are hingedly connected by an integral web 18. Bottom section 12 has a plurality of egg-accomodating cells 20 arranged in parallel rows. While the number and rows of cells may vary, the bottom section preferably consists of a dozen cells arranged in two parallel rows of six cells each.
A wide variety of materials may be used in the manufacture of the carton structures illustrated in the drawings. Molded paper pulp, pasteboard, plastic and the like, for example, may be used. A preferred material, however, is thermoplastic foam, such as, for example, foam polystyrene, or other polymers, such as polyethylene, polypropylene, polyvinylchloride, and the like. For purposes of illustration and as preferred embodiments, the drawings show egg cartons and locking mechanisms for the cartons of unitary construction produced by vacuum molding or match-molding techniques from a sheet of polystyrene foam.
In accordance with the invention, interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. The relationship between the interlocking means and the top and bottom sections of the carton, as shown in the drawings, will be used in the specification and claims for clarity, but it is to be understood that the interlocking means may be reversed with respect to the carton's sections without departing from the scope of this invention.
As embodied, the interlocking means includes a longitudinal locking lip 22 integral with and extending along at least a portion of the length of the top of bottom section's front wall 24, and a substantially horizontal locking flange 26 integral with and extending inwardly from and along a portion of the length of the bottom of the cover section's front wall 28 adjacent locking lip 22. The upper surface 30 of locking flange 26 engages the underside 32 of locking lip 22 when the carton is closed to lock the bottom and cover sections together.
A depending flange 34 integral with locking flange 26 extends downwardly and outwardly from the inner edge 36 of the locking flange to assist in the locking and unlocking of the locking mechanisms.
During closing of the cartons, the inner surface 38 of depending flange 34 engages the locking lip 22 and flexes locking flange 26 outwardly over the outer edge 40 of lip 22 until the flange is free to snap back into engagement with the underside of locking lip 22.
To open the container, the fingers are inserted between the bottom section's front wall 24 and depending flange 34, and the flange is pulled upwardly and outwardly to pull locking flange 26 out of engagement and over the outer edge 40 of locking lip 22.
As best shown in FIG. 1, there is provided an outwardly and laterally extending flange 42 that extends around the bottom of the cover section's rear wall, its sidewalls, and a portion of its front wall, and a corresponding flange 44 on the top of the bottom section's walls, the flanges 42 and 44 being in substantial flush load-bearing engagement when the carton is closed.
In accordance with one embodiment of this invention, and as shown in FIGS. 1--4, locking lip 22 and locking flange 26 of the interlocking means extend substantially along the entire front walls of the bottom and top sections. As best shown in FIG. 1, a portion of the bottom section's flange 44 is raised along the bottom section's front wall 24 intermediate its ends, and forms locking lip 22 of the interlocking means. Further, a portion of the cover section's flange 42 extends downwardly and outwardly along the section's front wall 28 and forms the leading edge 46 of the depending flange 34 of the interlocking means.
Thus, the upper surface 30 of locking flange 26 in this embodiment is above the plane of engagement between the cover and bottom sections' flanges 42 and 44, respectively, and approximately coplanar with locking lip 22 so that the flange snaps into engagement with the underside 32 of the lip during closing for more positive locking.
Preferably, and as best shown in FIG. 2, locking flange 26 and depending flange 34 are integrally molded with the cover section's front wall 28 from a single sheet of thermoplastic foam. A bulge 48 is thus provided in front wall 28 to permit flexing of locking flange 26, primarily around the juncture 50 between bulge 48 and front wall 28, over lip 22 during closing. Bulge 48 may be either rounded, as shown in FIG. 2, or of rectangular configuration, as shown in FIG. 3.
To effect a locking closure of the carton of FIGS. 1--4, cover section 10 is rotated about hinge 18 toward closing relationship with bottom section 12 and pressed downward until flanges 42 and 44 are in abutting engagement. As the carton is closing, locking flange 26 is flexed outwardly about juncture 50 by the inner surface 38 of depending flange 34 riding over the outer edge 40 of locking lip 22. When the carton is completely closed as shown in FIG. 4, locking flange 26 snaps back into engagement with the underside 32 of lip 22 to hold the sections together.
When it is desired to open the carton, flange 34 is grasped and pulled upwardly and outwardly. This results in locking flange 26 flexing about juncture 50 and being pulled out of engagement with locking lip 22.
In accordance with an alternative embodiment of this invention, and as shown in FIGS. 5--7, there is provided a plurality of intermittently spaced locking lips 22' and corresponding locking flanges 26' on the front walls of the carton similar to the single locking mechanism of the previous embodiment. As best shown in FIG. 5, the bottom section's flange 44 is raised and recessed at spaced intervals along the section's front wall intermediate its ends, and forms the plurality of locking lips 22' of the interlocking means. Similarly, the cover section's flange 42 includes a plurality of downwardly extending portions at spaced intervals along the section's front wall 28, and forms the leading edges 46' of the plurality of depending flanges 34' of the interlocking means. Between the plurality of spaced locking flanges and lips, the flanges 42 and 44 lie in abutting engagement with one another when the sections are in a closed-superimposed position.
Thus, the upper surface 30' of locking flanges 26' in this embodiment are above the plane of engagement between the cover and bottom sections' flanges 42 and 44, respectively, and are approximately coplanar with locking lips 22' so that they snap into engagement with the undersides 32' of lips 22' during closing for more positive locking.
Preferably, and as best shown in FIG. 6, locking flanges 26' and depending flanges 34' are integrally molded with the cover section's front wall 28 from a single sheet of thermoplastic foam. Hence, as in the previous embodiment, a bulge 48 is provided in front wall 28 to permit flexing of the locking flanges over the locking lips.
In this embodiment, and as best shown in FIG. 7, locking lips 22' are recessed so that the leading edges 46' of flanges 34' are substantially coplanar vertically with the leading edges of flanges 42 and 44. Hence, the locking mechanism of this embodiment does not project any singular element beyond the normal boundaries of the carton substantially preventing the carton from being accidentally opened during handling.
Locking of the carton is effected in a manner similar to the previous embodiment, cover section 10 being pressed down against bottom section 12 to cause locking flanges 26' to snap under and into engagement with their corresponding lips 22'.
To open the carton, the fingers are wedged between a number of flanges 34' and the bottom section's front wall 24, and the flanges are pulled upwardly and outwardly, pulling flanges 26' out of engagement with the locking lips.
To strengthen the interlocking means of this embodiment, locking flanges 26' and locking lips 22 are located adjacent the carton ribs 51 that form the egg-accommodating cells 20 in the carton.
It can be seen therefore that the bottom and cover sections of both embodiments can be easily, automatically, and positively locked together simply by moving the sections into closed position, and easily opened simply by pulling upwardly and outwardly on the interlocking means depending flange 34.
The integral web 18 connecting the rear walls 14 and 16 of the cover and bottom sections, respectively, of both embodiments is preferably doubly creased at 52 and 54 to provide a double hinge with a compressible midportion 56 between the creases that resiliently urges the cover and bottom sections apart so that locking flange 26 snaps tightly into engagement with the underside of the bottom section's protruding lip 22 when the carton is closed.
It is to be understood that the cartons described in the drawings and utilizing the locking mechanisms of this invention are preferred carton designs for eggs. The invention, however, is applicable to a variety of egg carton shapes and other similar cartons. An egg carton, for example, having three parallel rows of four egg-accommodating cells each could easily be used with the present locking mechanism.
The invention thus provides new and improved locking mechanisms for packaging cartons and particularly molded egg cartons. The locking mechanism facilitates the easy closing, positive locking, and easy opening of the cartons without the need for applying excessive pressure and without fear of damage to the cartons or their contents. Further, the locking mechanisms of this invention can be integrally molded with the egg carton from a single sheet of suitable material using conventional molding techniques.
The invention in its broader aspects is not limited to the specific details shown and described and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.