Containers And Plastic Snap-closures Therefor For Use With Automatic Capping Machines

Abstract

A container and interengageable plastic snap-closure cap adapted for cooperative use with a conventional high speed automatic capping machine to provide positive liquid-tight sealing of the containers by capping them in rapid succession while they are transiting the machine. The cap is shaped for appropriate orientation in the cap-feeding chute of the machine and for pressure application on the container by the machine. The cap may be manually removed and resealed on the container.

Description

BACKGROUND OF THE INVENTION

Containers with plastic snap-closure caps which are manually removable and resealable are known in the art, but to our knowledge none of these containers and associated caps are capable of being sealably assembled in rapid succession in a conventional high speed capping machine.

In modern distribution of merchandise in sealed containers, such as foods in wide-mouthed jars, for example, the high speed capping machine has become indispensable and is universally used. These machines conventionally apply to the container a screw-type or other twist-type cap, usually made of steel. Although use of metallic caps adds substantially to packaging costs, this has been tolerated because of the economies effected in saving of labor and time by the high speed automatic capping equipment.

Conversion to the use of snap-on plastic caps, if this could be satisfactorily accomplished with an adequate seal, would provide a substantial cost saving. For use on containers of polyethylene or similar plastic, the use of snap-on caps of like plastic has the further advantage over steel screw caps in having compatible temperature coefficients of expansion. When steel screw caps are used on plastic containers, the considerable disparity between the temperature coefficients of expansion of steel and plastic tends to loosen the seal when exposed to wide changes of temperature.

SUMMARY OF THE INVENTION

A principal object of the present invention is to provide a container and associated resealable snap-on plastic cap adapted to be assembled together using conventional high speed container capping equipment for liquid-tight sealing of containers of food-stuffs or the like, automatically at high speeds.

Another object is to reduce the cost of automatic packaging of foods by providing adequately sealed containers having snap-on plastic caps instead of screw caps.

A further object is to provide reusable snap-on plastic caps which may be applied to containers by conventional high speed capping machines.

Still another object of the invention is to provide an inter-engagement of container neck and plastic snap-on cap which has a stout liquid-tight seal that cannot be inadvertently released.

Still a further object is to provide a simple and effective manually releasable labyrinth seal between a container and a plastic cap capable of being snap-applied thereon.

With these and other objects in view which will become apparent as the description proceeds, our invention is comprised essentially of a container and associated plastic cap in which there is a labyrinthine interengagement of the cap with the neck of the container and in which the caps are adapted to be automatically snap-applied on the containers in rapid succession by conventional high speed automatic capping machines.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary side-elevational view, partly in section, of a jar and cap assembly of the invention.

FIG. 2 is an enlarged fragmentary sectional view of the interengageable labyrinth of the assembly of FIG. 1.

FIG. 3 is a view, similar to that of FIG. 2, showing a modification of the container.

FIG. 4 is a fragmentary side-elevational view, partly in section, of the snap-on cap engaged by the cap-engaging button of an automatic capping machine.

FIG. 5 is a fragmentary side-elevational view, partly in section, of the snap-on cap engaged in the cap-applying chuck of an automatic capping machine.

FIG. 6 is a bottom view of the chuck of FIG. 5, with the cap shown in FIG. 5 removed from the chuck which is fragmented and sectioned to show a section on the line 6--6 of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, the numeral 10 indicates a wide-mouthed container or jar which may be of any suitably rigid material such as polyethylene, polypropylene, or other polyolefin, polystyrene, composition, glass, metal, or the like. However, a preferred material from the standpoint of economy is polyethylene which may be inexpensively molded by blow molding or injection.

The jar 10 terminates at the top in a cylindrical neck 12 whose exterior surface extends downwardly for a short distance to a flat shelf 14 projecting radially outward for a short distance to intersect a downwardly and outwardly extending conical surface or closing bevel 16. The surface 16 in turn intersects a downwardly and inwardly extending conical surface or release bevel 18, the intersection of the two bevels forming a relatively sharp annular ridge 20. The bevel 18 terminates in a lower cylindrical neck 22 extending downwardly to intersect an inwardly belled portion 24 of the jar 10.

The inward cylindrical surface of the neck 12 extends downwardly to an internal bead 26 below the shelf 14 and then curves outwardly and then inwardly, generally paralleling the conical outer surfaces 16 and 18, to form an annular groove 28 disposed radially inwardly of the ridge 20.

In the case of containers molded from flexible resilient plastic materials such as polyethylene, the outward surface of the neck 12 is curved radially inwardly just below its top surface to form an annular flexible flange 30, as shown in FIGS. 1 and 2, providing an additional sealing feature, as will be later explained. However, an adequate liquid-tight seal is provided when the cylindrical neck is an annulus of uniform thickness as shown for the neck 12' of the container 10' of FIG. 3. The uniform thickness shape of the neck 12' is used for containers formed of glass or other inherently rigid materials not having the flexibility required of the flange 30.

The cap or closure 40 is a circular molding of flexible, resilient and locally distortable plastic material such as polyethylene, or the like. The cap 40 has a flat top portion comprising a circular central button 42 and a coplanar annular pressure ring portion 44 outwardly spaced therefrom and extending to near the outer edge 46 of the cap. Between the button 42 and the ring 44, the top of the cap 40 is depressed to form a flat annulus 48. The depressed annulus 48 is joined to the button 42 and the ring 44 by annular sloping shoulders 50 and 52 respectively, and another downwardly sloping shoulder 54 joins the outward periphery of the ring 44 to the depressed rim 56 of the cap 40. The button 44, annulus 48 and shoulders 50 and 52 serve to stiffen the top portion of the cap and such stiffening may be augmented, if desired, by suitably thickening the annulus 48.

Depending from the outward edge of the rim 56 is a cylindrical flexible skirt 58 having an internal annular ridge 60 appropriately spaced downwardly from the top to engage and retain the container ridge 20. A cylindrical sealing projection 70 depends from the inside of the cap 40 near the outward part of the ring 44 and forms the inward wall of a cylindrical annular upward recess 72 in the under surface of the cap, the recess 72 having a flat top surface 74. An annular vertical surface 76 forms the outward wall of the recess 72 and joins a flat outward radial surface 78 forming the under surface of the shoulder 54 and the rim 56. The lower outward surface of the projection 70 is beveled inwardly at 80 for guiding the cap 40 into engagement with the neck 12.

When the cap 40 is properly engaged with the jar 10, the projection 70, recess 72, surface 78 and ridge 60, constituting the sealing labyrinth of the cap, in conjunction with the neck 12, shelf 14 and ridge 20, of the jar, form a durable liquid-tight seal. On snapping the cap into place on the jar, the inward surface of the neck 12 is guided by the bevel 80 into engagement with the outward surface of the projection 70 which deforms resiliently to provide a tight seal. Under a capping thrust applied uniformly to the top of the cap, as by an automatic capping machine, the ridge 60 slides downwardly along the closing bevel 16 with appropriate local deformation of the cap, until the ridge 60 is engaged by the ridge 20.

This action sealingly engages the inward surface of the neck 12 against the projection 70, the top surface of the neck 12 against the top surface 74 of the recess 72 and the flat shelf 14 of the neck 12 against the flat surface 78 of the cap 40, the plastic cap being resiliently locally deformed in the process to provide durable effective sealing.

In the case of the flexible flange 30 of the neck 12 of the plastic container 10 shown in FIGS. 1 and 2, in addition to the sealing engagement of the inward side of the neck 12 against the projection 70 and the top of the neck against the top surface 74 of the recess 72, the outward edge of the flange 30 is downwardly deformed against the top portion of the outward annular surface of the recess 72 to provide an extra sealing effect.

When it is desired to remove the cap 40, the skirt 58 is manually deformed by a strong localized radially outward pull to slide an initial portion of the ridge 60 upwardly along the release bevel 18. This action disengages the respective portion of the cap, after which disengagement of the entire cap proceeds quite easily because of the non-freezing characteristic of the plastic material.

The caps 40 may be readily manually applied to the jars 10 and may also be conveniently and efficiently applied thereon by conventional high speed automatic capping machines of the type having a hopper mechanism which delivers caps from a hopper into a chute from the outlet of which they are properly positioned for engagement by a cap-engaging head or button on a horizontally oscillating arm which transfers the respective cap into position for engagement by a rotating chuck that applies the caps to appropriately positioned respective jars. An automatic capping machine of this general type adaptable for applying the caps 40 to the jars 10 is disclosed in U.S. Pat. No. 2,434,053.

The hopper mechanism of the automatic capping machine may desirably be of conventional type generally as described in U.S. Pat. No. 2,625,313 for a hopper cap feeder having a rotatable disk plate, slanted to the vertical, which picks up caps from a supply in the hopper by means of in-and-out reciprocating cap pick-up members or pins arranged so that the pins can enter the hollow side of properly oriented caps. The caps picked up from the hopper by the extended pins are carried around on the disk to the chute inlet and are dropped therein by appropriate retraction of the pins.

The chuck of the automatic capping machine may desirably be of conventional type generally as described in U.S. Pat. No. 2,593,794 for a rotatable cap-applying chuck having an endless helical contractile spring for resiliently gripping the cap.

FIG. 4 shows the cap 40 engaging the cap-engaging head or transfer button 90 of the automatic capping machine referred to in the foregoing (not shown) after it has fully engaged the cap 40 upon its release from the chute outlet (not shown) in conventional manner. The inside surface of the skirt 58 is readily engaged by the pick-up pins (not shown) of the hopper mechanism (not shown) of the capping machine. The button 90 has a top annular rim portion 92 of a diameter to be comfortably engaged within the inside surface of the projection 60 of the skirt 58. The portion 92 has a bevel 94 at the top outer edge to facilitate engagement with the cap 40. The button 90 is provided with peripheral flange 96 extending outwardly below the portion 92, whose top surface 98 provides a seat for the skirt 58.

The transfer button 90 functions to position the cap 40 below and in registration with a cylindrical chuck 100 along its vertical axis as shown in FIG. 5. The chuck 100 is threadedly engaged near its periphery with a chuck body 102 suitably rotatable and cam-controlled for vertical movement in conventional manner for engaging and removing caps 40 from the transfer button 90 and then applying the caps to the containers 10 by a downward thrust, as will be further described.

The chuck 100 has an axial cylindrical bottom opening 104 above which is a larger similar opening 106 in which is seated a shock absorbing elastic disk 108, preferably of sponge rubber or the like. A radial annular channel 110, of rectangular shape in a section on a vertical plane containing the axis, is provided in the wall of the opening 104 for housing and retaining an endless helical contractile spring 112 and three retractile cap jaw elements 114. Each of the jaws 114 is a sector of an annulus having an annular circumferential groove 116 in its outer peripheral wall, which provides a seat for the spring 112. The abutting edges of the jaws 114 are provided with bevels 118 to facilitate removal of the jaws from the chuck 100. The jaws 114 have a slip fit in the channel 110 and are composed of Micarta, Bakelite, or other hard synthetic resin, or composition, which will readily slip on the outer surface of the skirt 58.

Each of the inward surfaces of the jaws 114 is provided at its lower end with a bevel 120 which, together with the sloping peripheral shoulder 54 of the cap, facilitates entry and centering of the cap 40 in the chuck.

The cap 40, engaged in the rotatable chuck 100 as shown in FIG. 5, is disposed in the capping machine in axial registration with and above a jar 40 (not shown), conventionally momentarily held firmly at rest while transiting the capping machine on its container conveying mechanism (not shown). Under control of its cam mechanism, the rotating chuck descends and applies a downward thrust, effectively snapping the cap 40 on the jar 10, and then lifts free. This snap engagement stops the rotation of the cap which thereupon slips freely in the rotating jaws 114 until the chuck rises and disengages, the capped container then continuing its transit on the conveyor.

Specimens of the container 10 of this invention, molded of polyethylene, were filled with liquid foods and were then capped with caps 40 of this invention, also molded of polyethylene, using a conventional high speed automatic capping machine, substantially as described in the foregoing. The machine used was a Model LC 120 Resina Automatic Screw Capping Machine manufactured by Resina Automatic Machinery Company, Inc. of Brooklyn, New York.

It was found that the caps 40 were snap applied to the jars 10 with complete success and that the rotation of the chuck caused no difficulty whatever, since the jaws 114 merely slipped on the cap skirt 58 after the snap engagement was accomplished.

Capping of filled jars 10 with caps 40 was also done with the chuck 100 disengaged from its rotational drive so that it reciprocated vertically in its normal manner, without rotating. It was found that the snap engagement of the caps on the jaws was also completely effective under this condition .

Claims

What is claimed is:

1. A container and interengageable plastic snap-closure therefor, in which said container has a generally cylindrical flat-topped neck with a topmost portion whose exterior surface extends generally downwardly to intersect an outwardly extending flat annular shelf which intersects a downwardly and outwardly extending conical bevel that in turn intersects a downwardly and inwardly extending conical bevel to form an external annular ridge, the lower bevel terminating at an intersection with a lower portion of said neck, the inward surface of said topmost neck portion extending cylindrically downwardly to a point below said shelf, and in which said closure is molded of flexible, resilient and locally distortable plastic and comprises a circular cap whose top surface includes an annular flat pressure ring extending to near the outer edge of said cap, a dependent cylindrical outer skirt having an internal annular ridge space downwardly from its top, the undersurface of said cap having a dependent annular cylindrical sealing projection disposed under said pressure ring and forming the inward wall of an upward annular cylindrical recess, said recess having a flat top surface and an outer wall intersecting an outwardly extending flat portion of said undersurface, the respective components of said neck and said cap being so proportioned that the flat top portion of said neck is liquid-tight sealingly engageable with said flat top surface of said recess, said inward cylindrical surface of the topmost portion of said neck is liquid-tight sealingly engageable with the inward cylindrical surface of said recess, said flat annular shelf is liquid-tight sealingly engageable with said outwardly extending flat portion of the undersurface of said cap and said internal ridge of said skirt is snap-engageable over said external ridge of said neck.

2. The invention set forth in claim 1 characterized in that said container is molded of flexible, resilient and locally distortable plastic, that the outward surface of said topmost portion of said neck is curved radially inwardly to form an outward annular flexible top flange, and that said flange is so proportioned as to be downwardly deformable against the top portion of the outward wall of said recess.