Container end closure

Abstract

A food dispensing container is disclosed which includes a fiber tube, a bottom end closure, and a self-locking top end closure. The top end closure includes a generally flat laterally extending end portion, and an annular skirt portion extending axially from the end portion. A plurality of locking means are disposed in positions of remotely spaced adjacency on the end closure for holding the skirt portion in the fiber tube. Each of the locking means includes a plurality of axially spaced locking barbs and a reinforcing strut extending between the end portion and the skirt portion which prevents radially inward deformation of the locking barbs. The skirt portion and the fiber tube are dimensioned to provide an interference fit, and the locking barbs locally stretch the fiber tube so that the resilience of the stretched fiber tube forces the fiber tube onto the locking barbs. The locking means are spaced 120.degree. apart, and the locking barbs each extend through an arc of only 3.degree., whereby the force of the locally stretched fiber tube is concentrated on a small area of the locking barbs.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to plastic end closures, and more particularly to a self-locking plastic end closure for use on a fiber tube.

Paper fiber tubes (that is, tubes which include layers of fiber material wound such as in a helix one upon the other and secured together by an adhesive) have become widely used for dispensing containers in the food packaging industry. The paper of such tubes may be plain or it may be coated, waxed, resin-impregnated, or combined with other foils or films to provide a satisfactory container for various types of food products. The tubes are cut to the desired length of the container, and a plastic end closure is placed on each end of the tube to form the container.

Each end closure includes a generally flat round end portion and an annular skirt which extends from the end portion and which is received within the tube. In order to hold the end closure on the tube and seal the interface of the end closure and the tube, an adhesive is applied to the inside of the tube or to the skirt of the end closure prior to assembly. Although such adhesively held end closures have achieved wide commercial acceptance, it is desirable to eliminate the step of applying the adhesive and to provide an end closure which is secured on the tube without the use of an adhesive. This problem has existed for many years, but a plastic end closure which could be pushed onto the end of a fiber tube without breaking and which could be satifactorily secured to the fiber tube without an adhesive has not been provided in the art prior to the present invention.

SUMMARY OF THE INVENTION

The present invention provides a self-locking end closure for use with a fiber tube. The end closure is of plastic and includes a generally flat laterally extending end portion. An annular skirt portion extends axially from the end portion, and the skirt portion has a generally smooth outer surface for being received within the tube.

A plurality of locking means are arranged in positions of remotely spaced adjacency 120.degree. apart on the end closure for securing the end closure onto the fiber tube. Each of the locking means includes a plurality of axially spaced locking barbs extending radially outwardly from the outer surface of the skirt portion and terminating in a sharp edge. A reinforcing strut extends from the closure end portion to the skirt portion immediately adjacent the locking barbs and prevents radially inward deformation of the locking barbs and of the skirt portion adjacent the locking barbs. In this manner, the circumferentially spaced locking barbs are not forced radially inwardly when the end closure is pushed axially onto the tube, but, instead, the locking barbs radially outwardly deform the tube to locally stretch the tube so that the resilience of the locally stretched tube urges the tube onto the sharp edges of the locking barbs.

The arcuate extent of the locking barbs of each locking means is less than ten degrees and in the preferred embodiment is not greater than 3.degree.. This feature concentrates the resilient force of the locally stretched tube on a small area of the locking barbs to force the tube onto the locking barbs, and minimizes the force required to assemble the end closure onto the fiber tube to prevent breakage of the plastic end closure during assembly. In this manner, the invention provides a self-locking plastic end closure which can be assembled onto a fiber tube without breaking and which is secured on the tube without the need for an adhesive.

DESCRIPTION OF THE PREFERRED EMBODIMENT

These and other aspects and advantages of the invention will become readily apparent to those skilled in the art upon an understanding of the preferred embodiment of the invention shown in the accompanying drawings, wherein:

FIG. 1 is a perspective view of a dispensing container according to the principles of the invention;

FIG. 2 is a side elevational view of the end closure for the top of the dispensing container shown in FIG. 1;

FIG. 3 is a bottom view of the end closure shown in FIG. 2;

FIG. 4 is a cross sectional view taken along reference view line 4--4 of FIG. 1;

FIG. 5 is an enlargement of a portion of FIG. 4 showing a portion of one of the locking means provided by the present invention; and

FIG. 6 is a cross sectional view taken along reference view line 6--6 of FIG. 4, but with the cross-hatch lines omitted for clarity.

Referring now to the drawings in greater detail, FIG. 1 is a perspective view of a dispensing container according to the principles of the invention. The dispensing container shown in FIG. 1 is particularly adapted for use with food products and includes a paper fiber tube 11. The tube 11 is well known in the art and includes layers of heavy kraft paper wound in a helix one upon the other and secured together by an adhesive. The dispensing container shown in FIG. 1 also includes a bottom end closure 12 and a top end closure 14 which are secured on the ends of the fiber tube 11 to close the ends. In actual use, one of the end closures is first secured on the fiber tube 11 to form an open ended can, the can which is so formed is filled with the product which is to be dispensed, and the other end closure is then placed on the open end of the can to form the dispensing container.

FIGS. 2, 3 and 4 show the top end closure 14 in greater detail. The end closure 14 includes a stationary cap 15 and a rotatable disc 16. The cap 15 and the disc 16 are each injection molded, and the cap 15 is preferably made of a medium impact styrene while the disc 16 is preferably made of a flexible polyethylene. This provides a stationary cap which is rigid and a rotatable disc which is flexible so that the disc can be snapped onto the cap without breakage.

As best seen in FIGS. 1 and 4, the rotatable disc 16 includes a large arcuate shaped opening 17 for pouring or for receiving a spoon and a plurality of smaller openings 18 for dispensing the contents of the container by shaking. The rotatable disc 16 also includes a depending axle portion 19 which is snapped into a suitable opening in the center of the stationary cap 15, and the disc 16 is rotated to bring the openings 17 or 18 into alignment with a suitable opening formed in the stationary cap 15 and described below.

The construction of the stationary cap 15 is shown in FIGS. 2, 3 and 4. The cap 15 includes a laterally extending end portion 23 and an annular skirt portion 24 extending axially from the end portion 23.

The end portion 23 includes a support portion 26, an axially recessed center portion 27, and a conical connecting portion 28 extending between the support portion 26 and the recessed center portion 27. The support portion 26 includes an annular groove 29 extending about its outer circumference for receiving a depending lip of the bottom end closure of another container (not shown) for stacking purposes in a well known manner. The axially recessed center portion 27 includes a removable tab 30 which is defined by a reduced thickness outline portion 31 so that the tab 30 can be removed in the manner disclosed in U.S. Letters Pat. No. 2,961,132 to permit dispensing the contents of the container through the large opening 17 or the smaller openings 18.

As shown in FIGS. 3 and 4, the skirt portion 24 is substantially cylindrical and extends axially from the end portion 23 for being received within the fiber tube 11. The skirt portion 24 includes an inner surface 33 and a smooth outer surface 34, and the free end of the outer surface 34 is tapered to provide an entrant surface to assist in the assembly of the end closure 14 onto the fiber tube 11. The diameter of the outer surface 34 is approximately three inches in the embodiment shown in the drawings.

As shown in FIGS. 2 through 5, the top end closure 14 also includes a plurality of locking means 35. The locking means 35 are arranged in positions of remotely spaced adjacency on the end closure 14, and the structure of each of the three locking means is identical. Each locking means includes a plurality of axially spaced locking barbs 40, 41, 42, 43 and 44 (FIG. 5), each of which extend radially outwardly approximately 0.015 inches from the outer surface 34 of the skirt portion 24 and each of which terminate at a sharp edge. Each locking means 35 also includes a reinforcing strut 50, and each reinforcing strut 50 extends from the portion of the inner surface 33 adjacent the locking barbs 40 through 44 radially inwardly to the support portion 26 and the recessed center portion 27 and the connecting portion 28.

When the top end closure 14 is to be assembled onto the fiber tube 11, it is properly aligned with the fiber tube 11 and is displaced axially onto the fiber tube 11. This is commonly done with automatic machinery which positions the end closure 14 and applies a force to the support portion 26 to push the end closure onto the fiber tube 11.

The inside diameter of the fiber tube 11 and the outside diameter of the outer surface 34 (that is, the diameter of the cylindrical portion of the outer surface 34 from which the locking barbs project) are dimensioned to provide an interference fit. When the end closure 14 is assembled onto the fiber tube 11, the projecting barbs of each of the locking means 35 deform the portion of the fiber tube 11 adjacent thereto radially outwardly to locally stretch the fiber tube 11 in the manner shown in FIG. 6. The reinforcing strut of each of the locking means 35 prevents radially inward deformation of the locking barbs when the end closure 14 is assembled on the tube 11 to insure such stretching of the fiber tube at the location of each of the locking means. This stretching of the fiber tube 11 forces the tube onto the barbs 40 through 44 and deeply embeds the barbs in the fiber tube 11 to lock the end closure 14 thereon.

As further shown in FIG. 3, the locking means 35 are remotely spaced about the circumference of the skirt portion 24, and the locking barbs of each locking means extend only through a small arc 53. The locking means are spaced apart by an arc of at least ninety degrees, and in the preferred embodiment the locking means are 120.degree. apart. The locking barbs of the locking means each extend through an arc of less than 10.degree., and in the preferred embodiment the locking barbs each extend through an arc of not greater than 3.degree.. This feature of the invention concentrates the resilient force created by the localized stretching of the fiber tube 11 on a small area to provide a self-locking end closure in which the locking barbs are embedded in the fiber tube in the manner illustrated in FIG. 5 even when the fiber tube 11 is constructed of relatively hard kraft paper. Furthermore, this feature of the invention also minimizes the axial force required to assemble the end closure 14 onto the fiber tube 11 to prevent breakage of the end closure during assembly.

Although a preferred embodiment of this invention is illustrated it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed and claimed herein.

Claims

What is claimed is:

1. In combination, an end closure and a fiber tube, said fiber tube including a generally cylindrical wall, and said end closure being plastic and including a laterally extending end portion, an annular skirt portion extending axially from said end portion, said skirt portion having an inner surface and a generally smooth outer surface being received within said tube wall, and a plurality of locking means disposed in positions of remotely spaced adjacency holding said skirt portion in said tube wall, each of said locking means including a plurality of axially spaced locking barbs, each of said barbs extending radially outwardly from said generally smooth outer surface and terminating at a sharp edge, reinforcing strut means extending from said end portion to said inner surface solely at a location immediately adjacent said locking barbs and preventing radially inward deformation of said locking barbs, said locking barbs locally deforming the portion of said tube wall adjacent said locking barbs radially outwardly to stretch said portion of said tube wall to a position radially outwardly of the remaining portions of said tube wall intermediate said barbs, and the resilience of said stretched tube wall urging said fiber tube onto said locking barbs whereby said locking barbs lock said end closure onto said fiber tube.

2. The combination in accordance with claim 1 wherein said locking barbs and reinforcing strut means each extend through an arc of less than ten degrees.

3. The combination in accordance with claim 2 wherein said locking barbs and reinforcing strut means each extend through an arc of not greater than 3.degree..

4. The combination in accordance with claim 2 wherein said locking means are at least 90.degree. apart.

5. The combination in accordance with claim 4 wherein said locking means are 120.degree. apart.

6. The combination in accordance with claim 1 wherein said end portion includes a generally flat axially recessed center portion, and each of said reinforcing struts extend between said inner surface adjacent said locking barbs and said recessed center portion.

7. The combination in accordance with claim 1 wherein said locking means provide the sole means for holding said end closure on said tube.

8. The combination in accordance with claim 1 wherein said outer surface of said skirt portion from which said locking barbs project and said cylindrical wall of said fiber tube are dimensioned to provide an interference fit therebetween.

9. A plastic end closure comprising a laterally extending end portion, an annular skirt portion extending axially from said end portion, said skirt portion having an inner surface and a generally smooth outer surface, a plurality of locking means disposed in positions of remotely spaced adjacency along said skirt portion, each of said locking means including a plurality of axially spaced locking barbs, each of said barbs extending radially outwardly from said generally smooth outer surface and terminating at a sharp edge, reinforcing strut means extending from said end portion to said inner surface solely at a location immediately adjacent said locking barbs and preventing radially inward deformation of said locking barbs, and said locking barbs and reinforcing strut means each extending through an arc of less than ten degrees.

10. A plastic end closure in accordance with claim 9 wherein said locking barbs and reinforcing strut means each extend through an arc of not greater than three degrees.