Method for transversally sealing a tube of packaging material using an ultrasonic sealing device, an anvil and an ultra-sonic sealing device

Abstract

A method for transversally sealing a packaging material tube, comprises placing a transversal sealing section of the tube between a sonotrode and an anvil. The transversal sealing section comprises a first two-layer sub-section, a three-layer sub-section and a second two-layer sub-section, transmitting ultrasonic acoustic vibrations, having a frequency and an amplitude, from the sonotrode into the transversal sealing section, thereby melting the plastic foil in the transversal sealing section, and pressing the tube together between the sonotrode and the anvil to bond the plastic foil such that transversal sealing is formed. The anvil has a ridge comprising various sub-sections for receiving various ones of the sub-sections of the tube, wherein the ridge has equal height in at least some of the sub-sections. The frequency, amplitude, pressure and paperboard properties are chosen to achieve equal temperature in the first two-layer sub-section, the three-layer sub-section and the second two-layer sub-section.