EP2646333A1

EP2646333A1 - Crown cork

Info

Publication number: EP2646333A1
Application number: EP11805665.4A
Authority: EP
Inventors: Aleksander SZYMAÑSKI
Original assignee: Can Pack Metal Closures Sp Z Oo
Current assignee: Can Pack Metal Closures Sp Z Oo
Priority date: 2010-12-01
Filing date: 2011-11-30
Publication date: 2013-10-09
Also published as: WO2012074421A1; PL218389B1; PL393100A1

Abstract

A crown cork constituting a cylindrical stamped piece (1) made of sheet steel, in which the side surface is bent outward and has a shape characteristic of a crown (2), with a seal (3) with a thickened surrounding ring formed into a convexity (4), which in cross - section has a shape close to that of a right triangle, where the hypotenuse and seal edge form two sections connected with each other by a gentle curve, characterised by the fact that length of the leg opposite to angle x measured from the intersection point of the straight line described by section (a) and that leg to vertex (5) is at minimum 1.16 mm, while the value of angle x ranges from 25° to 45°, ideally 37°.

Description

Crown cork

The invention concerns a seal for a crown cork, popularly called a "bottlecap" and primarily designed as a closure for bottles.

A crown cork is used to close bottles containing beverages, especially soft drinks. Its role is to ensure a leak-proof seal and prevent carbon dioxide loss in case of carbonated drinks.

Crown corks manufactured to date consist of two parts: a steel body made by press forming a disk punched out of thin sheet steel, giving the disk its cylindrical shape with the surface of the sides characteristically formed into regular teeth, and a plastic sealing disc fixed to the internal surface of cylinder bottom, the aim of which is to ensure a leak-proof seal in combination with the surface of the bottle neck. The seals used have various shapes.

For example, British patent specification GB 714981 A (Bouchon Couronne, FR, published 08/09/1954) concerning a crown cork for bottles, describes a packing piece consisting of a thicker, external ring with square cross-section, and thinner internal disc; in addition, this central plate may have ball-shaped shoulders.

Patent specification WO 2009/007777 (Bindschedler Thomas Jean Noel, Merin Caballero Alfredo Abel, published 15/01/2009) describes a crown cork for bottles in which the seal placed on the internal side of the panel contacts and seals with the bottle edges after crimping. A double or single lip may be provided on the seal edge. In the case of double lip, the seal edge contacts the internal and external parts of the bottle neck. The single lip seals with the internal part of the bottle neck.

Commonly known seals may also have the form of a flat, circular surface with edges contacting upper surface of the bottle neck.

In the aim of reducing the production costs of crown corks, efforts are being made to reduce the amount of material used in their manufacture, e.g. by decreasing the thickness of the sheet metal used to make the stamped steel piece that makes up the body of the closure. One negative effect of reduced thickness of the sheet metal used in manufacture of crown corks is a reduction of sealing properties. With thinner sheet metal, there is greater risk of loss of the leak-proof seal, and beverage leaks can result or, for soft drinks, carbon dioxide may be lost to below the limit permissible for a beverage for consumption.

The purpose of the invention is to provide a strong, safe bottle seal, even when using thin sheet metal in crown cork production.

This purpose has been achieved by equipping the crown cork with a specially designed seal to ensure durability of the closure.

Employing this solution according to the invention in question also improves the durability characteristics in closures manufactured using standard sheet metal thickness.

The crown closure according to the invention is a cylindrical stamped piece of thin sheet steel constituting body of the closure, with the side surface bent outward into a shape characteristic of a crown. Moreover, the closure contains a packing insert (seal) fixed to the internal surface of the cylindrical steel body bottom. The seal is a flat synthetic ring consisting of thin synthetic layer made up of a flat internal surface and a thickened external ring. The external ring is formed into convexity, so that its internal side wall extends vertically up to the top of that convexity. It then runs down diagonally, smoothly transitioning into the horizontal part ending with the seal edge. The cross-section of the external ring convexity has a shape close to that of a right triangle, in which hypotenuse forms with seal edge two sections connected with each other by a gentle curve. It is characteristic of the closure that the straight lines containing these sections form an acute angle x ranging from 25 to 45 degrees. It is also a characteristic of the closure that the length of the leg opposite to angle x, constituting the internal side wall of the ring, measured from the flat internal surface bend point to the vertex is a minimum of 1.16 mm.

In the optimal production variant, angle x is 37°.

Owing to its new shape, convexity vertex enters the neck, thus reducing the diameter of the surface exposed to the pressure of gas enclosed in bottle to the minimum possible. Its shape, described by specified characteristic dimensions, guarantees that the leak-proof seal is maintained during shifts of the steel body under a pressure load, especially for products subject to pasteurisation processes.

An example of the subject of the invention is shown in the illustrations, where Fig. 1 presents cross-section of the crown cork, and Fig. 2 shows the section of seal fragment with convexity.

The crown closure for bottles according to the invention consists of a stamped metal piece 1, with its side surface bent outward in form of a characteristic crown 2 used to clamp the closure onto the bottle neck. Seal 3 is placed on the internal side of the stamped piece L Seal 3 forms a layer of the material which is responsible for tight adhesion of the closure to the bottle neck, and thus for the hermetic seal of the bottle. Usually, packing piece 3 is made either of natural or synthetic rubber, or other thermoplastic material or elastomer.

At the place where seal 3 contacts upper bottle neck surface, seal 3 has convexity 4 with a cross-section shape close to that of a right triangle, in which the hypotenuse forms with edge of seal 3 two sections a and b linked by a gentle curve. Vertex 5 is the highest point of the convexity, whereas the internal flat surface of seal 3 is the thinnest layer.

After placing crown cork on the bottle neck, vertex 5 goes into the neck. The length of the leg opposite to angle J , measured from intersection point of the straight line described by section a and that leg to vertex 5^ is 1.16 mm minimum. HoweveT, the desired effect is also guaranteed for leg lengths ranging from 1.16 to 2 mm.

The optimal value of the acute angle between straight lines containing sections a and b is 37°, however ensuring tight closing boundary parameters of this angle range from 25° to 45° degrees.

In the part above empty bottle space, the layer of packing piece 3 forms a uniform, thin lining. The most often frequently applied thickness of this lining is 0.1 mm, however this value may be altered if necessary. The standard diameter of packing piece 3 measured in the distance between vertexes 5 is 19 mm, whereas diameter of the whole packing piece is usually 24.76 mm.

Advantages of this solution include the possibility of reducing the thickness of the sheet metal in order to obtain the same closure parameters as for the solution employed so far, which translates into an economic advantage for the production of closures of this type.

Claims

Patent claim

A crown closure constituting a cylindrical stamped piece made of sheet steel, in which the side surface is bent outward and has a shape characteristic of a crown, with a seal with a thickened surrounding ring formed into a convexity, which in cross-section has A shape close to that of a right triangle, where the hypotenuse and seal edge form two sections connected with each other by a gentle curve, characterised by the fact that length of the leg opposite to angle x measured from the intersection point of the straight line described by section (a) and that leg to vertex (5) is at minimum 1.16 mm, while the value of angle x ranges from 25° to 45°, ideally 37°.