DE2601771A1 - SCREW CAP FOR CONTAINER - Google Patents

Description

nt lawyers

BE 17'276

Walter Wiedmer plastic form, Näfels

Screw cap for containers

The invention relates to an elastic screw cap Material for containers, especially for bottles that are temporarily under internal pressure, with an external, an internal thread supporting and the mouth edge of the container to grip around certain cap part and one within the same lying, to engage in the mouth of the container certain middle part, which a curved, acted upon by the internal pressure Has disc.

It is already known screw caps for containers, in particular to be provided made of elastic material for bottles which have a thread on the container neck. Usually

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plastic is used for this purpose. In contrast to the plastic which is intended for closures, which are simply pressed onto the container and then with a snap action hold tight, the plastic for screw caps must be harder, but should not be too hard to ground; one A certain degree of hardness is required on the one hand because of the mechanical stress on the locking thread, and on the other hand must Nevertheless, a certain elasticity must be present, so that when screwing the closure on the container by adjusting the closure to any irregularities and tolerances of the container a good seal is achieved.

The previously known screw caps made of plastic have a thread that practically over the entire axial The depth of the inner wall of the closure is sufficient. You want to achieve a secure sealing of the container by the threads serve as a kind of labyrinth seal, even if the closure has a central part that when put on is introduced into the interior of the container neck in order to achieve a first seal there.

Now, however, on the standardized containers, especially on the standardized beverage bottles, the external thread is not up to the brought up the upper edge of the container neck. This is not possible because it would otherwise cause the thread to end abruptly sharp edges would arise, which would hinder the mechanical screwing as well as the unscrewing. The thread therefore ends somewhat below this edge, and there remains a short unthreaded end section, which is connected to the opposite Internal thread of the screwed-on closure of the previously known type forms a cavity, which a Can represent leak. Such a leak is, however, in both beverage bottles and liquids that generate gas pressure such as mineral water, must etc. are undesirable, but also, for example, for bottles that are used for pasta

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ization of their contents must be heated, with high Internal pressures arise. If part of the content can escape, there is a risk that it will cool down later Negative pressure is created in the bottle, which can suck in air from the outside.

The invention now provides for avoiding these disadvantages.

According to the invention, the screw cap is the one mentioned at the beginning Kind designed so that between the certain surface of the cap part to rest on the mouth edge and the Internal thread a sealing bead is arranged.

The invention is illustrated by way of example with reference to the accompanying drawing explained in more detail; show it:

1 shows a closure screwed onto a bottle, where in the left half only the closure, in the right half the closure and the bottle are shown in section, and

FIG. 2 shows a detail from FIG. 1 on a larger scale.

A beverage bottle 1 is provided with an external thread 2. This thread ends, as can be seen from the left half of FIG. 1, so far away from the upper edge 3 of the bottle 1, that a threadless section 4 remains. According to the manufacturing standards for beverage bottles, this has a Diameter which is slightly smaller than the core diameter of the external thread 2.

A screw cap 5 is screwed onto the external thread 2, It has an outer cap part 6 and a central part 7 lying within the same, which extends into the interior of the bottle 1 protrudes. The cap part 6 has an internal thread

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provided, while the middle part 7 has a sealing lip 9 and a washer 10 which is curved _{towards the inside of the bottle, that is, when viewed downward in the figure, f.}

As can be seen, because of the threadless section 4, the internal thread 8 of the closure 5 is not over the whole axial length of the cap part 6 formed. Rather, the internal thread 8 also ends like the external thread 2 of the bottle 1 at a certain distance from that surface 11 of the cap part 6, which when the closure is in place on the edge the bottle rests on. The area between this surface and the end of the external thread is defined by a bead 12 taken, which both against the section 4 and against that of this with the adjoining, the external thread 2 bearing portion formed shoulder 13 rests. (For the sake of clarity, distances are drawn between the cap and the bottle; in reality, of course, the closure rests seamlessly against the bottle).

A gas pressure, for example the pressure of carbonic acid, acts on the disk 10 inside the bottle; the resulting force is shown with an arrow P. Their action initially causes the lock to be raised slightly relative to the Bottle 1 within the tolerances between external thread 2 and internal thread ■ 8. If the pressure increases further, the vertical force P a further lifting of the transition point between the disc 10 and the cap part 6. Because of the toothing 2-8, however, the outer edge of the cap part 6 can no longer yield, and a deformation of the cap part occurs, which ^ · exaggerated in Fig. 2 with dashed lines is shown. With this deformation, the surface 11 of the cap part is raised at the mouth of the bottle 1 and takes thereby the dotted inclined position. This has the consequence that the transition point 14 between the surface 11 and the adjacent Bead 12 against the threadless section 4 of the bottle

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is pulled. As a result of this drawing by the distance d (which, as I said, is actually very small), the The bead is pressed more strongly against the threadless section 4, as a result of which the sealing effect is improved. Try with to pasteurizing bottles have confirmed this; at the same time it was found that by attaching the bead 12 and by the rounding of the transition point 14, which is as shown can be designed as a recess with a rounded base, a stress reduction in the cap part 6 is achieved as a result of which the earlier occasional tearing off of the cap part along one of this point to the outside Edge 15 leading level was avoided. Nevertheless, it is advisable not to round off said edge 15 too much and also not to deepen the transition point 14 too much, so that the cross-section of the cap part lying between these points, which has to absorb the greatest stresses, remains as the largest cross-section.

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Claims (1)

Patent claims Screw cap made of elastic material for containers, especially for bottles that are temporarily under internal pressure, with an external one Internal thread (8) carrying and the mouth edge (3) of the container (1) to encompass certain cap part (6) and a central part located within it and intended to engage in the mouth of the container (7), which has a curved disc (10) acted upon by internal pressure, characterized in that that between the to rest on the mouth edge (3) certain surface (11) of the cap part (6) and the Internal thread (8) a sealing bead (12) is arranged. 2. Screw closure according to claim 1, characterized in that the sealing bead (12) has a smallest Has diameter which is smaller than the smallest diameter of the internal thread (8). 3. Screw closure according to one of the preceding claims, characterized in that the transition point (14) between the bead (12) and said surface (11) of the cap part (6) is rounded. 4. Screw closure according to claim 3, characterized in that the transition point (14) as a recess with a rounded Reason is formed. 11/27/1975
Sb / dh / li 609837/0279