BACKGROUND OF THE INVENTION
Reference is made to my copending provisional application for letters patent, Serial No. 60/251,102, filed Dec. 5, 2000, from which a claim of priority is made.
This invention relates generally to the field of threaded closures for containers having a correspondingly threaded finish, typically, containers for soft drinks and the like. Such closures are normally provided with a tamper-indicating ring which is frangibly interconnected to a lower free edge of the closure which becomes at least partially disconnected from the closure when it is unthreaded. This connection indicates that the container has been at least partially opened after initial filling. In some cases, the ring remains attached to the container finish. In other cases, the ring splits and remains hingedly attached to the closure for recycling.
In the commonly used construction, the container finish is provided with an annular bead positioned beneath the lowermost portion of the threads, which bead engages inwardly flexed tabs on the inner surface of the tamper ring as the unthreading of the closure proceeds. The tabs are so constructed that they pass over the bead when the closure is installed. In one form of operation, commonly referred to as a first mode, the tabs are of relatively thick cross section and do not substantially flex during installation and removal of the closure, but merely pivot at a base portion along a line of interconnection relative to an annular inner surface of the tamper-indicating ring.
- SUMMARY OF THE INVENTION
It is desirable that the operative upper surface of the tabs engage a lower surface of the bead on the container finish as rapidly as possible once unthreading commences, so that the frangible bridges interconnecting the tamper-indicating ring with the cap element of the closure may be broken simultaneously with the breaking of the seal at the mouth of the container, so that unthreading operation proceeds relatively uninterruptedly thereafter. It is also desirable that there be as little radially-outward deflection of the tabs during installation as possible.
BRIEF DESCRIPTION OF THE DRAWINGS
Briefly stated, the invention contemplates the provision of a threaded closure of the type above-described in which the tabs are pivotally interconnected at a lower edge of the tamper-indicating ring after molding, and are subsequently seated in corresponding recesses in the inner surface of the tamper-indicating ring by pivoting the same from a relatively transversely-extending orientation to a relatively axially oriented one. When the closure is installed, the upper ends of the tabs are flexed within an annular recess provided by a relatively thin upper portion of the ring approximately 0.020 inch radially outwardly. When the corresponding bead on the container finish has been passed, the upper portion of the ring which has been radially outwardly stressed, contracts to urge the upper free end of the tabs radially inwardly to position the upper end immediately beneath a lower surface of the bead on the container finish, so that when an unthreading operation is commenced, the engagement of the tab with the bead produces an axial force which is immediately transmitted to the frangible bridges interconnecting the tamper-indicating ring with the cap element for prompt severance.
In the drawings, to which reference will be made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views.
FIG. 1 is a fragmentary schematic sectional view, partially in elevation, of an embodiment of the invention in installed condition upon a container finish.
FIG. 2 is a similar schematic sectional view showing the embodiment in detached condition.
FIG. 3 is an enlarged sectional view corresponding to the lower left-hand portion of FIG. 2.
FIG. 4 is a fragmentary sectional view corresponding to that seen in FIG. 2, showing certain of the component parts in altered relative position.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT
FIG. 5 is a sectional schematic view of an alternate form of the embodiment.
In accordance with the invention, the device, generally indicated by reference character 10 (FIG. 1) is shown in installed condition upon a threaded finish 11 of a soft drink or similar container 12. The finish includes a threaded cylindrical member 13 defining a mouth 14 of the container and having an outer surface 15 provided with a continuous thread 16. Disposed below a lower portion 17 of the threads is an annular bead 18 and an optional tamper resistant flange 19, all of which are known in the art, the details of which form no part of the present disclosure.
The device 10 includes a known cap element having a horizontally extending end wall 20 and a cylindrical side wall 21 having a threaded inner surface 22, as well as a serrated outer surface 23. A lower edge 24 thereof defines a slitting line 25 which operation forms frangible bridges (not shown) which interconnect the tamper-indicating ring 27, again, as known in the art.
The ring 27 includes a relatively thin walled upper portion 30 and a relatively thick walled lower portion 31 terminating in a lower free edge surface 32. An upper inner surface 33 defines an annular recess 34, which as will more fully appear, accommodates a portion of flexible resilient tabs. A lower inner surface 35 defines a plurality of generally rectangular recesses 36 which resiliently retain the tab elements 40 in upright condition.
The tab elements 40 are generally similar, and are distributed at substantially equal intervals along the inner periphery of the tamper-indicating ring. As seen in FIG. 1, they are each molded for convenience in transverse orientation, as indicated by reference character 41, to include an elongated main body 42 bounded by a lower surface 43, an inner surface 44, an outer surface 45, and having a pivotally interconnected edge 46. The tabs also include a tapered free end portion 47 bounded by an inner surface 48, an end surface 49 having an inner edge 49a, as well as an axially-oriented surface 50 and a radially-oriented surface 51 which define an outwardly extending projection 52 adapted to be seated within the annular recess 34.
After the molding operation of the device is completed, the tab elements 40 are moved from their radially inwardly extending horizontal position using devices known in the art for this purpose. With such movement, they are pushed into the axially-oriented condition in which they engage the respective recesses 36 to be retained for only limited pivotal movement about the edge surface 32.
When the closure is installed, a radial deflection of as little as 0.020 inch is required to enable the edge 49 a to pass the annular bead 18 on the container finish. The radially outwardly developed force is transmitted through the projection 52 of each tab to result in a momentary outward stress on the upper portion of the tamper-indicating ring. This stress is removed as soon as the bead has been passed, and the return force positions the free end of the tabs beneath the lower surface of the bead 18, so that when an unthreading operation is commenced, an axial force is immediately developed which results in the fracturing of the frangible bridges interconnecting the cap element with the tamper-indicating ring, in known manner.
Owing to the fact that the lower parts of the elongated tabs are substantially captivated by engagement of the same within corresponding recesses in the inner surface of the lower portion of the tamper-indicating ring, it is impossible for the tabs to operate in other than the so-called first mode of operation. The engagement of the tabs with the recesses is maintained not only by the provision of a force fit, but by the fact that the sides of the recesses lie in planes which converge radially inwardly toward the axis of the closure. The tabs can thus be made using less thermoplastic material, typically, polypropylene, than is normally the case in the manufacture of prior art closures having relatively thick tabs to ensure rigidity. Since the tabs will not normally possess a high degree of resiliency, the provision of a projection extending radially outwardly to contact an inner surface of the upper portion of the tamper-indicating ring provides the necessary radial force to ensure engagement of the free end of the tabs with an undersurface of the container finish bead. The fact that very little radial movement is required facilitates the installation of the closure, and the resilient contraction of the upper relatively thin portion of the tamper-indicating ring assures that the tabs will not clear the bead on the container finish when the closure is unthreaded.
Turning now to the alternate form of closure shown in FIG. 3, parts corresponding to those of the principal form have been designated by similar reference characters with the additional prefix “1”.
In the alternate form, the tab elements 140 are thicker, and are of generally rectangular cross section. To accommodate them, the upper portion 130 is substantially thinner in cross section relative to the lower portion 131. This form of the embodiment is particularly suited for use with relatively softer materials, such as polyethylene.
I wish it to be understood that I do not consider the invention to be limited to the precise details of structure shown and described in the specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.