US 3215297 A
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Description (OCR text may contain errors)
1965 D. D. ACTON ETAL 3,215,297
CLOSURE CAP Filed March 25, 1964 i .5. T n:
LWEXTQRS DAN/6L D Harv/Y GEORGE 1 566 2 'IIIIIIIIIIIIIIIIIIII/IIIIIII/I mm IIIIII ATTOP/Yiy United States Patent 3,215,297 CLOSURE CAP Daniel D. Acton and George J. Foss, Lancaster, Ohio,
assignors to Anchor Hocking Glass Corporation, Lancaster, Ohio, a corporation of Delaware Filed Mar. 25, 1964, Ser. No. 354,532 2 Claims. (Cl, 215-43) The present invention relates to an improved closure cap for sealing containers and more particularly to an improved closure cap formed of a combination of metal and plastic.
The improved closure cap has a relatively thin outer metal shell and a molded plastic liner covering the inner surfaces of the cap including the cap cover and the depending skirt. The novel design of this two-piece cap takes particular advantage of the individual characteristics of the metal and of the plastic to obtain the best combination of the stiffening and decorative features of metal with the improved sealing and corrosion resisting qualities of resilient plastic. As will be more fully described below, a unique combination of the materials is provided whereby an improved sealing action results between the inner plastic liner of the cap and the rim of the related container. An improved seal is provided between the cap and the container even where the container finish has minor irregularities and in addition an initial sealing and a subsequent resealing are provided with relatively low application and removal torques.
As will also be more fully described below the resilient plastic liner with its unique design also provides a closure with a long shelf or storage life wherein the resilient nature of the plastic reinforced by the more rigid metal shell cooperate with the container threads or lugs to prevent an accidental loss of seal. The plastic liner itself also provides a surface of exposure to the container contents which is inert with respect to virtually all regular foods or cosmetics or similar items which are normally packaged using such a closure cap.
Accordingly, it is an object of the present invention to provide an improved closure cap of metal and plastic which takes advantage of a combination of the differing characteristics of both materials to provide an improved cap.
Another object of the present invention is to provide an improved closure cap formed of plastic and metal and particularly adapted for providing a perfect seal with the container finish under conditions of relatively low application and removal torque.
Another object of the present invention is to provide an improved plastic and metal closure cap wherein a tight seal is obtained even with containers having rim dips or other minor imperfections in the sealing surfaces of the container rims.
Another object of the present invention is to provide a closure cap which has greater flexibility in conforming to the container finish and which is easier to apply and remove from a container.
Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employ ment of the invention in practice.
A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:
FIG. 1 is a perspective view partially in section of a preferred embodiment of the closure cap of the present invention;
3,2l5,297 Patented Nov. 2, 1965 FIG. 2 is an enlarged sectional view partially cut away of the closure cap of FIG. 1;
FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;
FIG. 4 is an enlarged fragmentary view of the closure cap of FIG. 1 illustrating the cap in sealing relationship with a container rim;
FIG. 5 is an enlarged fragmentary view of a sealing rib in engagement with a container rim;
FIG. 6 is a sectional view taken along line 66 of FIG. 4; and
FIG. 7 is an enlarged sectional view partially cut away of another embodiment of the closure cap of the present invention in sealing relationship with a container rim.
Referring now to the drawings which illustrate a preferred embodiment of the invention and more particularly to FIG. 1, the closure cap 1 has an outer metal shell 2 and an inner plastic liner or closure 4. The metal shell 2 has a cover 5 and a depending skirt 6 and is stamped from a lacquered piece of tinplate by methods and machines well known in the art. If desired, spaced tabs (not shown) may be formed in the lower edge 7 of the metal shell 2 to provide for a better interlock between the metal shell 2 and the plastic closure 4.
The plastic closure 4 is preferably formed separately from the metal shell 2 by injection molding. Although any suitable inert plastic having a resilient quality may be used in molding the plastic closure 4, it has been found preferable to use polyethylene.
During the molding process, threads 8 are formed on the inside of the plastic closure 4 which conform to corresponding threads on a container finish.
After the plastic closure 4 is formed, it is inserted into the metal shell 2 and the lower edge 7 of the metal shell 2 is turned in and is embedded in the lower edge 9 of the plastic closure 4. By embedding the exposed lower edge 7 of the metal shell 2 in the plastic closure 4, as shown in FIGURE 2, the lower edge 7 is protected from corroding and from the peeling of the lacquer from the shell 2. In addition, the embedded edge 7 firmly grips the plastic closure 4 to lock it in place within the metal shell 2.
As best illustrated in FIGS. 3 and 4, the plastic closure 4 has a sealing zone 15 depending from its cover portion 16 which engages the rim 17 of a container 12 to form a seal therewith. The sealing zone 15 is formed during the molding of the cap.
Preferably, the sealing zone 15 comprises concentric annular ribs 18 which have a wedge-like cross-section. A generally triangular cross-section 19 is preferred because it provides a minimum surface area contact between the ribs 18 and the container rim 17. Although a single sealing rib 18 is effective for smaller caps, two or more sealing ribs are preferred as this causes the sealing forces to be more evenly distributed.
The number of ribs actually used depends on the size of the closure cap. One or preferably two ribs are used on smaller caps while up to six ribs may be employed on larger caps.
The improved sealing action resulting from the tapered ribs 18 may be best understood by reference to FIGS. 5 and 6. As illustrated in FIG. 5, the rib 18 has its lower contact portion 13 positioned on a top surface of the container rim 17 and has a relatively flat annular portion of the cap cover 5 backing up and reinforcing the plastic rib 18 and the relatively thick plastic sealing zone 15. The metal cover 5 stiffens and reinforces the plastic so that application of the cap 1 to the sealed container with a relatively small sealing force on the cap sealing threads moves the rib 18 downwardly onto the container rim 17 with a relatively great sealing pressure at the small linelike contact area between the rib 18 and the container rim 17. As also illustrated in FIG. 5, the concentrated force applied to the sealing rim at its narrow line of contact is distributed by the upwardly flaring shape of the rib 18 so that the force is more or less equally distributed over a wider annular area of cover 5 as illustrated generally by the arrows 23. It is also clear that the metal covers being relatively stiff acts to maintain the rib 18 in its sealing contact after the seal is completed and during the storage period or shelf life of the sealed container even over relatively long periods.
FIG. 6' is a sectional view showing an arcuate section of the container rim 17 and illustrating a corresponding arcuate section of the plastic sealing rib 18 forced against the surface of the rim 17 after closure cap 1 has been applied to a container. The rib 18 is shown conforming to an irregular surface of rim 17 having a pronounced rim dip 27. The flexible nature of the plastic rib 18 together with the relative stiffness of the annular backup portion of the metal cover 5 cooperate to force line-like lower edge 13 of the sealing rib 18 into a tight seal along the entire surface of the container rim 17 as the lower edge 13 of the rib 18 conforms itself under the concentrated sealing forces resulting from the combination.
Minimum application and removal torques are also achieved with the above described sealing structure due to the small contact area between the ribs 18 and the container rim 17. This feature is of particular importance as it permits ready removal of the cap 1 by the user even after long storage periods.
FIG. 7 illustrates a modified embodiment of the closure cap of the present invention. The modified embodiment 20 differs in that the sealing ribs 21 and 22 have differing positions and sizes in order to accommodate them to a curved container rim 24. The outer longer rib 21 makes contact with the outer marginal surface 25 of the container rim 24 and the inner shorter rib 22 makes contact with the inner marginal portion 26 of the container rim 24.
' In other respects, the operation of the modified cap is the same as that of the embodiment of FIGS. l-6.
As illustrated in FIGS. 2 to 4 an annular flexing space 10 is preferably provided between the skirt 11 of the plastic closure 4 and the skirt 6 of the metal shell 2. This space is provided by a difference in the alignment of the metal shell 2 and of the skirt 11 of the plastic closure 4. A slight flare is normally provided in the metal skirt 6 during the stamping operation to facilitate the removal of the shell 2 from the stamping die. To this relatively slight taper is added an outward flare in the molded skirt 11 of the plastic closure 4. This provides the space 10 as illustrated in the FIG. 4 with an increasing width towards the cap top 5. The space 10 has been found to provide the below described improved sealing elfect with a flare between the cap skirt 6 and the plastic closure skirt 11 in a range of from about 1 to 1% degrees.
The space 10 between the two skirts 6 and 11 not only facilitates the assembly of the closure cap 1 but it also provides a greater tolerance in the closure 1 in accommodating for variations in the size and shape of a container.
For example, containers vary slightly in size and may be slightly enlarged due to limitations in their manufacture. Similarly, the shape of the container may be slightly out of round. While these variations are relatively minute, they can have an adverse effect on the quality of the seal of the container. The provision of a flexing space 10 between the skirt of the plastic closure 4 and the metal shell 2 not only renders these glass variations less critical, but also permits a better seal on the container with a uniform and satisfactorily low removal torque. The flexing space 10 permits the plastic closure 4 to yield and to adjust in shape to more precisely conform to the shape of the container finish 14. This yielding and adjusting supplements the inherent flexibility and resiliency of the plastic closure 4.
It will be seen that a novel and effective combination results from the plastic closure 4 supported within the metal shell 2. As described above, a relatively thick skirt portion 11 on the plastic closure 4 effectively engages the container threads due to its own resiliency and due to the spacing 10 provided between it and the outer metal shell 2 permitting controlled flexure. The same plastic closure 4 has the integral tapered ribs 18 formed on a plastic sealing zone 15 which is in direct contact with the supporting cover 5 of the metal shell 2 so that the forces generated by the application of the closure to the container threads are effectively concentrated in the line-like edges of the flexible sealing ribs where the sealing pressure is relatively large and highly concentrated and where the combined plastic and metal sealing zone retains the tight seal indefinitely over long periods of storage. Thus, the described combination of a metal shell and a plastic inner closure with varied spacing between the metal and the plastic and the novel sealing rib shape cooperate to provide the improved sealing and removal torque characteristics.
The metal shell may also be conveniently decorated by the usual lithographing methods before being shaped to enhance the appearance of the cap. The plastic insert is particularly useful for sealing products which require a protective coating to guard against deterioration of the exposed portions of the closure caps. The combination of metal and plastic in the cap described results in overall material savings of a significant amount.
As various changes may be made in the form, construction, and arrangement of the parts herein without departing from the spirit and scope of the invention, and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.
Having thus described our invention, we claim:
1. A composite closure cap for a container having a rim comprising the combination of a relatively thin metal outer shell having a cover and a depending skirt terminating in an inwardly rolled bead, a molded flexible plastic liner being relatively thick throughout and having a cover portion in engagement with the metal cover, a plurality of downwardly extending annular sealing ribs on the liner cover for engaging and sealing the container rim, said metal cover and said liner cover cooperating to press the annular ribs into sealing engagement with the rim and to confine deformation of the liner to the sealing ribs whereby the ribs seal dips occurring in the surface of the rim, said plastic liner further having a relatively thick depending skirt portion including container engaging threads, said plastic liner skirt being spaced from the metal skirt by an upwardly flared zone extending from a point adjacent the lowermost threads on said liner skirt to the metal cover portion and said plastic liner skirt terminating in a lower edge portion in which the rolled bead of the skirt is embedded for securing 'said liner against rotation and for sealing the edge of the bead against corrosion.
2. The closure cap according to claim 1 wherein the plurality of sealing ribs comprises an inner rib and a radially spaced outer rib, said outer rib being longer in height than the inner rib whereby the outer rib deflects outwardly and the inner rib deflects inwardly when engaging and sealing a container rim surface which is rounded in a radial direction.
References Cited by the Examiner UNITED STATES PATENTS 2,735,565 2/56 Wheaton et a1. 215-43 2,768,762 10/56 Guinet 21545 3,074,579 1/63 Miller.
FOREIGN PATENTS 526,174 6/56 Canada. 1,218,437 5/60 France.
FRANKLIN T. GARRETT, Primary Examiner. GEORGE O. RALSTON, Examiner.