Bottles and jars – Closures – Cap type
Patent
1990-10-30
1993-03-30
Shoap, Allan N.
Bottles and jars
Closures
Cap type
215329, 215350, 215351, 220296, B65D 4104
Patent
active
051976218
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a screw cap made from plastic according to the preamble of claim 1. These types of screw caps are manufactured in very large numbers by the injection molding process and are used to close off containers of the most varied kinds. Screw caps made of plastic have found an application mainly in the refreshment drinks branch, where the screw caps are screwed automatically onto the filled bottles on rapidly moving filling lines.
A problem with conventional screw caps occurs in that they must be screwed on with a definite application of torque, in order to ensure a sealed fit. Thereby, the screw movement is normally limited, since the bottle opening comes into contact with the base of the screw cap. The danger thus exists that the cap is screwed on with excessive torque, so that subsequently it can hardly be manually unscrewed. Overwinding of the threads can also occur in certain cases, since the bottle openings, especially in the case of glass bottles, can exhibit large variations of tolerance.
SUMMARY OF THE INVENTION
It is therefore a purpose of the invention to design the screw caps of the type mentioned in the introduction so that the screw-on movement is no longer limited, or no longer exclusively limited, by the base of the screw cap, and so that screwing on of the cap with too great a torque onto the container opening can be prevented. This purpose is achieved, according to the invention, with a screw cap exhibiting the characteristics of claim 1.
The brake element, arranged in the region of the helical line of the external thread of the container, arrests the screwing on procedure without the opening of the container, with full torque application, at the same time coming into contact with the screw cap base. When the external thread makes contact with the brake element, the screw-on force is transformed into a radial force component, since the external thread has a tendency to override the brake element and with that to be radially displaced outwards.
Depending on the design of the brake element and the elastic properties of the material, the rest position of the screw cap can be retarded. With that, it is especially advantageous if the brake element possesses an override surface which runs approximately parallel to the middle axis of the screw cap. Apart from that, the override surface can be inclined at an angle running through the middle axis of the screw cap. The override surface is thus formed like a ramp, onto which the external thread ascends with increasing radial tension.
The brake element can be integrated into the internal thread or it can be formed separately from the internal thread. The braking element can also possess a profile which is formed as a thread flank for the internal thread. The brake element obtains an additional function in this way. This function can be extended if the screw cap possesses one or more support ribs near the screw cap base to hold an inserted sealing disk in place, and if the braking element possesses a profile that runs in the plane of the support ribs. Thus, a part of the sealing disk rests upon the brake element.
The previously mentioned multi-function of the brake element can thus be especially easily achieved if, in plan, it possesses the shape of a wedge, which extends through a sector of at least 90 degrees. With that, the override surface is arranged on the wide end of the wedge which must possess a definite minimum width in order that the start of the external thread always strikes the brake element.
BRIEF DESCRIPTION OF THE DRAWINGS
A version of the invention is depicted in the drawings, and is more exactly described in the following section.
FIG. 1 is a cross-section through a screw cap according to the invention,
FIG. 2 is a cross-section through a screw cap, screwed onto a container opening according to FIG. 1,
FIG. 3 is a part-cross-section through the closure arrangement according to FIG. 2,
FIG. 4 is a variation of the screw cap inner wall on a slightly smaller scale.
FIG. 5 and FIG. 6 are
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Bartl Franz T.
Breuer Hans-Werner
Crown Cork AG
Schwarz Paul A.
Shoap Allan N.
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