US2164957A - Cap closure seal - Google Patents

Description

n Filed Dec. l, 1937 Kals SJreenhH Patented `lulry 4, 1939 UNITED STATES PATENT OFFICE Application December 1, 1937, Serial No. 177,444 In Sweden December 3, 1936 4 Claims.

This invention relates to closure caps for bottles and the like.

In conventional cap closures the circular top portion of the cap is tightened with or without insertion of a sealing gasket, against the bottlerim around the mouth. As is easily understood, perfect sealing depends on the radial width of that annular surface of the cap which contacts the bottle-rim and upon the pressure of the cap against the bottle-rim. It is, therefore, of paramount importance for a durable sealing that, after the capping operation, the cap is not displaced cr subject to any deformation impairing the two above mentioned factors.

In the conventional closures the circular top portion of the cap shell is usually plane or slightly convex, Consequently, in a cap shell of this type, the top portion offers little resistance to the forces, which, in case of overpressure in the bottle, tend to convex it. If the contents of the bottle have been introduced under overpressure and the bottle, before use, is stored for some considerable time or is subject to great variations in temperature, it happens that the upper portion oi' the cap assumes gradually a convex shape. This deforming of the cap may have the effect that the sealing against the bottle-rim is impaired partly by the reduction of the radial width of the contacting surface, partly by the decrease 30 of the cap pressure against the rim.

The present invention has for its object to improve the said closures in the respect mentioned preferably by giving both, the bottle-head, or more particularly the rim thereof around the mouth, and the cap shell, the latter before or during the capping operation, a continuously curved convex shape, which corresponds as closely as possible to the convex shape of the cap shell that may arise by the action of the overpressure in the bottle.

The invention is illustratively exemplied in the accompanying drawing, in which:

Figures l and 2 illustrate an embodiment of the invention.

Figure l is an elevation of the bottle neck before application of the cap.

Figure 2 is one half of an axial section on a larger scale through a bottle neck with a cap applied thereto.

Figure 3 shows a modied embodiment of the bottlehead, in elevation.

Figure 4 shows a sectional view of a cap of a known initial shape.

As shown in Figures l, 2 and 3 the rim I around the bottle-mouth is convex so that most of it,

when seen in axial section, approaches a spherical zone'. However, the invention is not limited to an exactly determined convex shape but includes all variations similar to the convex shape which a normal cap would assume under overpressure in the bottle. The contour of convexity may preferably have a radius, which is smaller than the diameter of the cap and the corresponding cross section respectively through the bottle-head, and the center of which is located within the bottle-mouth. The contour` of convexity may also be thought to be composed of several spherical arcs, provided the contour rises in a continuous curve towards the bottle-mouth, as is clearly shown in Figure 2. 'Ihe convexity terminates downwardly on the out-side of the bottle at the edge 2, the so-called sealing edge, with which the cap shell 3 (Figure 2) is, in known manner brought into engagement, during the capping operation by the skirt 4 of the cap shell being rolled in below the edge 2 into a groove 8. The said operation is, as usual, performed mechanically, generally by means of an elastic ring, provided in a capping head, which ring is compressed around the bottle-head, while the cap, by a plunger or the like, is pressed against the bottlemouth. The cap thus being subjected to a well adapted sealing pressure, it is deformed from its original shape, shown in Figure 4, under simultaneous shrinking and stretching, to fit snugly over the outer contour of the bottle-head. A corresponding change of shape is also effected on the sealing insertion 5 in the cap shell, in the cases where such insertions are used, see Figure 2. From Figure 2 it will be seen that the effective tightening surface of the rim extends, as shown in section, over the entire radial thickness .6 of the wall of the bottle neck.

To avoid with certainty the deforrnng` of the cap shell by overpressure in the container the `dome-shaped portion of the cap shell should have an altitude substantially equal to the radius of the mouth of the container.

From the foregoing it will be clear that a principal feature of the invention is to shape the rim of the bottle-neck and the top of the cap so as to substantially follow an imagined spherical segment.

The termination of the convex surface by a suitable sealing edge is of importance for an effective tightening against the convex rim and the application of the cap shell so that the same cannot lift itself from the bottle-head after the capping pressure has ceased. For this purpose it is also desirable that the skirt of the cap engage the edge around the bottle-mouth at each point of the edge. To replace the skirt by fingers grasping under the edge, as has previously been proposed, would' not at all suilice for a durable and reliable closure.

In order to obtain this edge the outside of the bottle-head may be shaped in many different Ways. For caps to be removed by being slit up, for example, by means of a tearing tab I3, the bottle-head may be shaped with a peripheral groove 8, Figure 1, as usual, or with a shoulder I2, according to Figure 3, extending around the mouth.

Finally, it is pointed out that the convexity of the bottle-head is not necessarily restricted to exactly the above described shape of the bottlehead for making possible the engagement of the cap shell; other suitable shapes may be used Within the scope of the present invention.

Of course, it is possible, when manufacturing the cap, to give to its top the required convex shape.

The combination of a convex bottle neck rim with a cap having a. dome-shaped top portion may also be used Without a sealing insertion.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In combination with a bottle neck, a closure cap comprising a continuously curved domeshaped top portion having its greatest inner periphery in contact with the greatest outer periphery of the bottle neck, said dome-shaped cap portion having an altitude substantially equal to the inner radius of the mouth of the bottle neck and being supported over the entire radial thickness of the Wall of the bottle neck.

2. A combination, as claimed in claim l, in which the greatest inner periphery of said dome- `shaped cap portion contacts the greatest outer periphery of the bottle neck in a horizontal plane below the level of the mouth of the bottle neck.

3. A combination, as claimed in claim 1, in which the upper rim of the bottle neck has a curved shape substantially corresponding to the inner surface of said dome-shaped cap portion.

4. A combination, as claimed in claim 1, comprising further a sealing insertion between the upper rim of said bottle neck and said domeshaped cap portion, the upper surface of said sealing insertion having a shape substantially corresponding to the inner surface of said domeshaped cap portion.

ROLF STEENHOFF.

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