METHOD AND DEVICE IN A PACKAGING MACHINE FOR ACHIEVING A STABLE AND REPRODUCIBLE GEOMETRY OF A FORCED PREFORMED TUBULAR-SHAPED WEB

摘要

The invention relates to a method in a roll-fed packaging machine for achieving a stable and reproducible geometry of a forced preformed tubular-shaped web of a thin packaging material when a longitudinal sealing operation is performed to said tubular-shaped web creating a continuous tube. The method is characterized by engaging the tubular-shaped web with a curved envelope surface (9) of a retaining element (5), said envelope surface (9) being formed to at least partly encapsulate the consecutively formed tubular-shaped web, and the engagement being made by means of at least one sub atmospheric pressure drop. The invention also relates to a device for carrying out the method.