Method and apparatus for calibrating packaging containers

Abstract

Packaging containers for liquid contents, for example milk, are normally manufactured from laminated packaging material including a carrier or core layer of fibre material which is coated on each side with plastic layers. In order to facilitate folding of the material, this is normally provided with a pattern of weakening crease lines which facilitate the reforming into the desired packaging container configuration. A method of retroforming or calibrating a packaging container for realising more accurate final configuration, sharper fold lines and thereby for imparting to the packaging container improved steadiness and stability comprises the steps of surrounding the packaging container with a forming device adapted to the final configuration of the packaging container, and of displacing parts of the forming device towards one another so that the free space for the packaging container is briefly reduced. An apparatus for carrying the method according to the present invention into effect comprises a forming device with moving forming parts which, in the closed position, define a forming cavity of a volume which amounts to between 100 and 110 per cent of the theoretical minimum volume of a processed packaging container.

Dependencies are inferred from the claim text.