GB2097380A

GB2097380A - Manufacture of necked containers, particularly glass bottles

Info

Publication number: GB2097380A
Application number: GB8113201A
Authority: GB
Original assignee: Rockware Glass Ltd
Current assignee: Ardagh Glass Ltd
Priority date: 1981-04-29
Filing date: 1981-04-29
Publication date: 1982-11-03
Also published as: GB2097380B

Abstract

The internal neck diameter of glass containers is made uniform by moulding the neck interior during parison-formation with annular ring 8 which forms the top of outer plunger 6. Inner plunger 7 is retracted while air is blown through 6 into mould cavity 5 to form the parison. <IMAGE>

Description

SPECIFICATION Manufacture of necked containers, particularly glass botties This invention relates to the manufacture of necked containers, particularly glass bottles.

Glass containers are conventionally manufactured on machines using moulding techniques involving blowing a hollow molten blob of glass against the inner wall of one or more moulds. In a particularly widely used system a glass blob is blown in a first moulding step to form a parison which is then blown in a second mould to form the final container. Contact of the molten glass with the mould walls cools the glass to a point at which the container may be removed from the final mould without losing its shape and subsequently it is allowed to cool under suitable conditions. Many millions of bottles and jars are made in this way every year and it is crucial to the economics of the manufacturing process that they are made by automatic machines with a very fast cycle time.

The use of blow moulding techniques of the type just noted leads to the production of containers with standardised external dimensions.

However, the internal dimensions may vary slightly from container to container. This is not usually a matter of any consequence since containers mass produced in this way do not have to be filled brim full and accordingly quite large tolerances on internal dimensions are often acceptable since they do not adversely affect the capacity of the bottle or jar, i.e. it will still hold the desired quantity of, for example, milk, beer, spirits or jam.

Although internal dimensional tolerances for bottles and jars can be quite wide, it is clearly desirable to keep them as narrow as possible, particularly if the containers are to be subsequently handled by automatic filling machinery and/or going to be subjected to a capping or other closure affixing process where variations in the internal diameter of the neck could adversely affect the smooth running of automatic machinery used for that purpose. The classical approach of sealing wine bottles with corks uses a compliant sealing member which takes up any variations in size but modern substitutes for corks such as plastics stoppers are easier to use if tight neck-size tolerances are observed in the manufacture of the glass container itself.In security closures for spirits bottles (to prevent refilling of empty or partially empty bottles with unauthorised additives) which are located within the neck portion of the bottle there is a particular need to work to Isw dimensional tolerances.

Quite clearly a low size tolerance may be set arbitrarily and all containers lying outside the tolerance limits may be rejected in order to produce sets of finished containers all within the tight tolerance. This is clearly uneconomic if the tolerance is not one easily achieved using the moulding techniques commonly practised.

We have now found that glass containers oF various types, particularly spirit bottles, may be produced with very tight dimensional tolerances on the neck opening by a standard moulding method if means are provided to define a moulding surface in the interior of the container aperture during the parison forming stage of moulding the container.

Thus according to a first feature of the present invention there is provided a method of manufacturing a container from a semi-molten mouldable material, particularly glass, wherein the container is formed by moulding a preform against the inner walls of a mould, wherein during at least one stage the inner wall of the container opening extending from the container aperture towards the interior of the container is in contact with a walldefining moulding member.

In the manufacture of glass containers using a so-called independent section or similar automatic blow moulding machine, this may be achieved by modifying the plug which normally enters slightly into the opening of the bottle in the first of the two moulding steps into two parts, a central part which may be retracted in order to allow blowing air into the interior of the gob to form the parison and an outer annular part which lies against the glass being moulded to define an inner, usually cylindrical, surface adjacent the container opening in the finally moulded container.

Thus according to a further feature of the present invention there is provided moulding apparatus for moulding a container from molten material, particularly glass, the apparatus including a two-part plug and two or more mould sections cooperating therewith, these sections and plug constituting when assembled together a moulding cavity for the container, wherein the plug is formed of a central portion and an outer portion, the central portion being retractable from within the outer portion to enable blowing air to be passed under pressure through the outer portion into the interior of the mould in order to force the material of the container against the walls of the so-assembled mould.

The invention is illustrated by way of example with reference to the accompanying drawings which show parts of a mould assembly for moulding glass bottles for bottling spirits.

In the drawings: Figure 1 is a longitudinal section through parts of a mould and mould cavity for moulding a whisky bottle; Figure 2 is a section similar to Figure 1 showing different stages in the operation of the mould assembly, two different stages of operation being drawn each side of the centre line of the mould.

Referring to the Figures, a so-called blank mould assembly includes mould members 1 and 2, a transfer sleeve 3 and a plunger unit 4.

Between the mould halves 1 and 2 is a moulding cavity 5, the lower end of which can be seen and it may be seen that it defines the external shape of the topmost portion of the neck of a whisky bottle.

In normal operation, the mould halves 1 and 2 would close round a molten glass gob and following withdrawal of the plunger 4 air would be blown into the interior of the blank mould in order to force the glass out against the walls of mould members 1 and 2 to form the parison.

According to the present invention, the plunger 4 has been constructed as an outer member 6 and an inner member 7 which may be moved axially relative to one another as well as moved axially together to bring them into the position shown in Figure 1. In operation, the members are brought together for the insertion of the gob into the blank mould, and subsequently the inner member 7 is withdrawn as shown in the lefthand side of Figure 2 and compressed air blown into the cavity via the member 6 to form the parison. During this forming, the outer surface of an annular ring 8 forming the portion of member 6 uppermost in the drawings, acts as a mould surface for the inner bore of the neck adjacent the opening. After blowing has formed the parison, member 6 is withdrawn to the position shown in the right hand side of Figure 2, and the bottle removed from the blank mould to the blow mould for final forming, following which it is removed from the mould and cooled.

It is found that using this technique, bottles can be produced at normal speeds but with a much smaller variation in neck bore size than previously.

Claims

CLAIMS 1. A method of manufacturing a container from a semi-molten mouldable material wherein the container is formed by moulding a preform against the inner walls of a mould wherein during at least one stage the inner wall of the container opening extending from the container aperture towards the interior of the container is in contact with a wall defining moulding member. 2. A method according to claim 1 wherein the mouldable material is glass, the container is formed by a two-stage moulding method and the inner wall of the container opening is in contact with a wall defining moulding member during the first moulding stage. 3. A method of manufacturing a container from a semi-molten mouldable material substantially as hereinbefore described with reference to the accompanying drawings. 4. Moulding apparatus for moulding a container from molten material the apparatus including a two-part plug and two or more mould sections cooperating therewith, these sections and plug constituting when assembled together a moulding cavity for the container, wherein the plug is formed of a central portion and an outer portion, the central portion being retractable from within the outer portion to enable blowing air to be passed under pressure through the outer portion into the interior of the mould in order to force the material of the container against the walls of the so assembled mould. 5. Apparatus according to claim 4 and constituting part of an independent section glass container moulding machine. 6. Apparatus according to claim 4 and substantially as hereinbefore described with reference to the accompanying drawings. New claims or amendments to claims filed on 20 April 1982 Superseded claims 1-6 New or amended claims:

1. Moulding apparatus for moulding a necked container from semi-molten mouldable material the apparatus including a two-part plug and two or more mould sections cooperating therewith, the mould sections and plug constituting when assembled together a mould cavity for the container with the plug extending into the neck portion of the mould cavity, wherein the plug is formed of a central portion and an outer portion, the central portion being retractable from within the outer portion to enable blowing air to be passed under pressure through the outer portion into the interior of the mould in order to force the mouldable material against the walls of the mould cavity of the so-assembled mould.

2. Apparatus according to claim 1 and constituting part of an independent section glass container moulding machine.

3. Apparatus according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

4. A method of manufacturing a necked container from a semi-molten mouldable material wherein the container is formed by moulding a preform against the walls of a mould cavity which method comprises, during at least one moulding stage, loading the preform into moulding apparatus as claimed in any one of claims 1 to 3, retracting the central portion of the plug from within the outer portion and blowing air under pressure through the outer portion into the interior of the mould in order to force the mouldable material against the walls of the mould cavity of the assembled mould.

5. A method according to claim 4 wherein the mouldable material is glass, the container is formed by a two-stage moulding method and there is used moulding apparatus as claimed in any one of claims 1 to 3 during the first moulding stage.

6. A method of manufacturing a necked container from a semi-molten mouldable material substantially as hereinbefore described with reference to the accompanying drawings.

7. A necked container manufactured by the method claimed in any one of claims 4 to 6.