US3021993A - Carton lock - Google Patents

Description

Feb. 20, 1962 M. B. KENNEDY ETAL CARTON LOCK Filed June 2, 1960 Fig. 2

INVENTORS MANLE) B.Keuu5 y LEWIS B. A EXANDER Fig. 4 IO VAT TQRNEYS United States Patent Office 3,621,993 Patented Feb. 20, 1962 3,021,993 CARTON LOCK Manley B. Kennedy, Walla Walla, and Lewis B. Alexander, Sunnyside, Wash., assignors to American Can Company, New York, N.Y., a corporation of New Jersey Filed June 2, 1960, Ser. No. 33,574 3 Claims. (Cl. 229-36) This invention relates to an improved locking construction for a carton, in which opposed panels or walls of the carton are engaged together in a manner to substantially prevent their subsequent disengagement without mutilation of the carton forming material. Because such a locking operation is, as a matter of economic necessity, frequently required to be performed by high speed automatic equipment, it is essential that the locking operation be accomplished in a manner which does not interfere with the speed of operation and results in a lock having the desired characteristics. One problem which arises in a performance of this locking operation is caused by the relative flexibility of the paperboard material from which the carton is most commonly constructed, the paperboard being sufiiciently flexible so that stability of the members to be engaged is frequently inconsistent.

It is the principal object of this invention to provide an improved form of locking construction which imparts a greatly improved stability and flexibility to the carton material in the area of the locking elements, and to insure automatically positioning of the locking elements so that locking engagement is made certain. Other particular objects and advantages of the invention will become clear from the following description in connection with the appended drawings, in which:

FIGURE 1 is a plan view of a carton blank incorporating a preferred embodiment of the invention;

FIGURE 2 is a perspective view of a set-up carton made from the blank of FIGURE 1;

FIGURE 3 is an enlarged perspective view partially cut awa, of the female locking element of the carton as it is set up in position for locking engagement; and

FIGURE 4 is a cross sectional view taken along the lines 44 of FIGURE 3.

Referring first to FIGURE 1, the carton blank of this invention is made from a suitable material of foldable yet relatively still composition, such as paperboard, plastic, various laminated materials and the like. A preferred material, commonly employed, is paperboard having a thickness of from about .010 inch to .030 inch. The blank is suitably cut and scored along the hinging score lines 1 to 9 inclusive to provide a series of walls, panels and flaps including front wall or panel 10, bottom wall 11, rear wall 12, top or cover wall 13, locking panel 14, end walls 45, dust flaps 16 and glue flaps 17. Locking panel 14 has formed on the remote edge thereof an arrow-shaped male element 15 having laterally spaced locking barbs 15a at the lateral termini thereof. Front wall 10 has a female locking element formed therein by longitudinal cut lines or slits and lateral out line or slit 19, the area defined by these out lines providing a deflectable portion the function of which will be explained later herein. Positioned below (FIGURE 2) female cut line 19 is a pair of score lines 18, these score lines being positioned so that their upper ends terminate adjacent the lower ends of cut lines 20 and their lower ends terminate adjacent the inner ends of hinging score lines 1 and 2.

The aforementioned score lines dividing the walls and panels from each other provide a hinging relationship of these structural elements, so that the carton may be conventionally set up as shown in FIGURE 2. In this position, walls 10, 12 and 45 are erected perpendicularly to bottom wall 11, with glue flaps 17 folded inwardly into superposed position with respect to the inner surfaces of Walls 45, to which they may be attached by suitable adhesives as indicated in FIGURE 1, by staples, or by any other suitable means. Obviously, a conventional locking construction whereby flaps 17 were engaged with walls 45, alternatively could be employed. Dust flaps 16 are then folded to overlie bottom wall 11, and cover wall 13 is folded over to close the open top of the receptacle previously formed.

Referring also to FIGURE 3, it will be seen that as front wall '10 is erected perpendicularly to bottom wall 11, such as by a force A applied to wall 10, score lines 18 will provide in efiect a stiffening strut, serving to assist in the resistance to this folding motion of the portion of front wall 10 in the immediate vicinity of score lines 18. The interruption 26 in the score line hinge connecting wall 10 to wall 11, provided by the spacing beyond out line 19 between score lines 1 and 2, further increases the resistance of this portion of front panel 10 to the folding movement. The presence of female out line 19 prevents this resistance eflect from extending therebeyond into the area 25 of front wall 10 above cut wall 19, so that as the pressure is applied to erect front wall 10 a natural opening of the female locking element results, as graphically illustrated in FIGURE 3.

This automatic full opening of the female locking element provided by slit 19, and increased in magnitude by the presence of slits 24) presents a degree of entrance area which insures the entrance of male locking element 15, even under conditions of highest speed machine operation, as cover wall 13, with locking panel positioned substantially perpendicularly thereto, is brought into position to close the carton. After release of the plow or other means by which wall 10 is erected perpendicularly to wall 11, locking means 15 having just been inserted, the natural resilience of the carton material in the area 25 and in the area laterally just beyond cut lines 20 causes that area to attempt to snap back, and thus assures engagement of the edges of barbs 15a behind the terminal edges of slit 19, for positive locking engagement of panel 14 to wall 10. It will be seen that with respect to the direction of entrance of element 15 into cut line 19, score lines 18 lie beyond the female cut 19.

FIGURE 4 shows in enlarged section the strut forming characteristic of score lines 18, by which a significant stiffness is imparted to wall 10 to facilitate opening of the female locking means as previously described.

Having now described a preferred embodiment of the invention, it is to be understood that the obvious modifications thereof which will be apparent to those skilled in the art are also intended to be included within the scope of this invention, and that the invention therefore is to be limited only as set forth in the appended claims.

We claim:

1. A carton including a pair of opposed panels to be locked together, a wall member to which one of said panels is integrally connected along a hinge line defined by a line of weakness by which said one panel may be resistably hinged to lie at a substantial angle relative to the wall member, locking means comprising a pair of laterally spaced male members on the other of said panels and female means in said one of the panels comprising a laterally positioned cut line the edges of which are adapted to engage edges of said male members for locking enagement therewith, said hinge line being provided by a score line which is discontinuous in at least part of the area beyond said female cut line, the carton also including stiifening means integrally formed into said one panel beyond said cut line and adapted to facilitate opening of said female locking means by planar separation of the portions of said one panel lying to opposite sides of said out line for engagement therein of the male locking means upon the hingglng of said one panel relative to said wall member, said stiffening means comprising a pair of spaced, longitudinally directed score lines impressed into said one of the panels in the area between said female cat line and said discontinuity of the hinge score line.

2. A carton according to claim 1, in which the terminal ends of said stifiening score lines adjacent the female cut line are positioned intermediate the ends of said female out line.

4 A, n. a i t s a n 2! f th r, includilig a pair of spaced, longitudinally directed cut lines extending from and connected With said female cut line intermediate the ends thereof, saidtpair of cut lines extending in the direction away from said hinging score line. References Cited in the file of this patent UNITED STATES PATENTS 1,738,744 Walter Dec. '10, 1929 1,876,063 Kronenberger A Sept. 6, 1932 2,304,362 Huye Dec. 8, 1942 2,846,132 Carpenter Aug. 5, 1958 2,975,953 Muth Mar. 21,, 1961

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