DE3428191A1 - Process for producing a pressure-resistant packaging container - Google Patents

Abstract

A process for producing a container for packaging liquid under gas pressure is proposed. The container is to be made of a material the production of which requires less energy than that for comparable metal containers. When a composite material of plastic and aluminium is used, a high stability is achieved by first forming from a blank of composite material a sleeve (2), clamping the open ends (3) thereof and then stretching the sleeve longitudinally and transversely. Covers (4, 5), also consisting of a composite material, are sealed into the open ends. <IMAGE>

Description

Method for producing a pressure-resistant packaging

prior art container The invention is based on a method for producing a packaging container according to the preamble of the main claim. To the Production of cans is known, for example, from DE-AS 19 44 490, initially a cylindrical or conical body made from a blank of a flexible Roll the composite material and seal the overlapping edges together or weld seam. The open ends of the fuselage are made by heat-sealed seams Attached cover, which also consist of a composite material.

Such cans are heat sterilizable and especially for packaging usable from canned food; however, they are not resistant to pressures in the 3 range of 5 to 6 bar, which will occur with packaged carbonated beverages previously used cans made of metal, in particular aluminum, for its production a relatively large amount of energy has to be expended.

Advantages of the invention The method according to the invention with the characterizing Features of the main claim has the advantage that when using an expandable, for example from DE-PS 23 16 513 known composite material, for its production less energy than is necessary for sheet aluminum, pressure-resistant packaging containers can be produced that are much cheaper with the same capacity are known as aluminum cans. Such composites have a middle layer made of thin aluminum foil, which provides both barrier and carrier properties, and outer layers of plastic, at least one of which is biaxial stretched film, which acts as a stretching agent. When using such The composite material is strengthened by the longitudinal and transverse expansion, so that its resilience is increased. Furthermore, such containers are according to The contents can be easily crumpled up.

The measures listed in the subclaims are advantageous Further developments and improvements of the method specified in the main claim are possible.

Drawing The method according to the invention is illustrated using the figures explained in more detail in the drawing in the description below. It show figure g to 3 different stages in the formation of a container body in cross-section and FIG. 4 shows a container produced by the method in cross section.

Description of the invention For forming the hull 1 of a pressure-resistant A flexible composite material is used, in which between plastic layers, which act as a stretching agent, sealing medium and corrosion protection, an aluminum foil is arranged, which acts as a gas and moisture barrier and strengthens the composite and gives a certain rigidity. Such a composite material has, for example following structure (from inside to outside): polyethylene 50 / um thick, soft aluminum 60 / µm thick, stretched polyamide 30 / µm thick and stretched polypropylene 40 / µm thick. Printing ink and a heat-sealing lacquer can also be applied to the outside.

First, a blank is made from such a composite material a cylindrical sleeve with overlapping edges formed under the action be sealed by pressure and heat to form a longitudinal seam. The overlap seam can also be covered on the inside with a strip that opens up the inside is sealed. Alternatively, the plastic can be used in a known manner be pressed at the edge so that it flows over the aluminum cut edge and they covers.

To form a stable body 1 with narrowed ends 3, 4 is the sleeve 2 clamped tightly at its end.

For example, grippers 10, which have a mandrel ll with a slightly conical end 12 and a sleeve 13 surrounding it with a conically narrowed one End of 14 have. At its end face, the mandrel 11 has a diameter that is somewhat is smaller than the inner diameter of the composite material sleeve 2 and the end 14 the sleeve 13 has a smallest diameter, which is the outer diameter of the composite material sleeve 2 corresponds. To the Clamping the ends 3 of the composite sleeve 2 are first the sleeves 13 over a length of about 5 mm over the ends 3 of the Sleeve 2 pushed. Then the mandrels 11 are in the sleeves 13 against their ends 3 moved so that they are in the encompassed by the sleeves 13 ends 3 of the composite material sleeve 2 penetrate, thereby widening these ends 3 a little and narrowing them against the conically Press the ends 14 of the sleeves 13. Simultaneously with or after this gas-tight clamping the free ends 3 of the composite material sleeve 2 is equiaxed over the sleeves 13 a cylindrical hollow form 16 is pushed. Then a hole 15 in A pressure medium, preferably compressed air, is passed into the sleeve 2 to one of the mandrels 11 and a pressure built up at which the sleeve 2 inflates barrel-shaped with her However, the outer wall does not come into contact with the inside, or only with slight pressure the hollow form 16 arrives (Figure 2). Both or only one of the grippers will be on it 10 moved away from each other so that the sleeve 2 is stretched longitudinally while at the same time additional pressure medium is introduced into the sleeve 2.

After moving the two grippers 10 apart by a certain The distance is increased by further supply of pressure medium into the sleeve 2, the pressure in this further increased until they are also under transverse stretching of the material Assuming the shape of the finished hull 1 with its outside on the inside of the Hollow shape 26 is applied (Figure 3). For shaping a rounded transition between the ends 3 and the cylindrical part of the fuselage 1 adjoins the conical narrowed end 14 of the sleeves 13 a dome-shaped projection 17, which is from the hollow shape 16 is included.

In addition, it is noted that the individual processes also differ from one another can be carried out independently, for example in such a way that the sleeve first stretched longitudinally and then expanded by introducing a pressure medium will. Longitudinal stretching can also be dispensed with.

After the internal pressure in the fuselage 1 has been reduced, it is released, by first pulling the two mandrels 11 further apart, then the both sleeves 13 also move further apart and finally also the Hollow form 16 is withdrawn. When pulling off the sleeves 13 they are slightly conical shaped ends 3 of the body 1 from the conically narrowed ends 14 of the sleeves 13 temporarily elastically deformed.

To complete the container is first at one end 3 of the Fuselage 1 a bottom cover 4 and, after filling, a head cover 5 with the fuselage 1 connected. The covers 4, 5 have an outwardly curved mirror, one on its edge upstanding ring area 7 and an adjoining flange 8, which may have notches. The lids 4, 5 are in the flared ends of the fuselage 1 inserted, the flange 8 bent outwards around the ends 3 and the connection is sealed under the action of pressure and heat.

The lids 4, 5 are preformed by deep-drawing or deep-drawing and embossing. They also consist of a composite material whose structure is from the inside out on the outside, for example, is: polyethylene 50 μm thick, aluminum 30 μm thick and polyvinyl chloride 400 µm thick.

For making a container with a capacity. of 333 ml (= 12 oz) will first be a composite 1 ~ # Erkstoffrhülse 2 formed, whose diameter is 43 mm and whose length is 130 mm. Through longitudinal and transverse stretching around 30 0 each gives a hull with a length of around 158 mm. Different would also be of the same elongation in the longitudinal and transverse directions of the material a transverse expansion of more than 30% and a longitudinal expansion of correspondingly less, for example about 15% conceivable.

The expansion of the composite sleeve to a fuselage can also can be carried out with the soil already sealed in. This procedure can be carried out at the same time a leak test can be carried out on the container, which is open on one side.

- blank page -

Claims (5)

Claims 1. A method for producing a pressure-tight packaging container, in which a body with a longitudinal seam is formed from a composite packaging material and attached the ends of which are each attached to a cover, characterized in that both ends (3) of the fuselage (l) are tightly clamped into the fuselage (1) with a pressure medium Overpressure is introduced and the fuselage (1) is clamped by pulling the Ends (3) is stretched. 2. The method according to claim 1, characterized in that in the fuselage (l) First a certain overpressure is generated and then a longitudinal stretching is carried out while further pressure medium is supplied. 3. The method according to claim 2, characterized in that according to the Longitudinal stretching in the fuselage (.1) increases the pressure of the pressure medium to expand it will. 4. The method according to claim 3, characterized in that the body (i) is widened in a cylindrical hollow shape (.16). 5. The method according to any one of claims 1 to 4, characterized in that that the ends (3) of the body (1) with a conical mandrel (11) and a conical Sleeve (13) existing grippers (io) are clamped with conical expansion.