Transversal sealing system and a method for transversally sealing a tube of packaging material

A transversal sealing (TS) system for a packaging machine, said sealing system comprising

• an ultrasonic arrangement arranged to face an outside surface of a tube of packaging material from a first sealing direction, wherein the first sealing direction is perpendicular to a feeding direction of the tube, wherein the tube comprises a longitudinal sealing (LS) area in which at least two layers of packaging material are overlapping,
• an anvil arranged to face the outside surface from a second sealing direction, wherein the second sealing direction is opposite to the first sealing direction,
• wherein the ultrasonic arrangement comprises
• a sonotrode arranged to apply ultrasonic vibrations such that an inner layer of the packaging material is at least partly melted,
• a first pressure plate arranged next to the sonotrode and upstream the feeding direction of the tube, wherein the first pressure plate is non-oscillating,
• a second pressure plate arranged next to the sonotrode and downstream the feeding direction of the tube, wherein the second pressure plate is non-oscillating, and
• a third pressure plate placed in a groove in the sonotrode,
• wherein the sonotrode is arranged to provide a TS-LS overlap pressure in a TS-LS overlap area, the first pressure plate is arranged to provide a first pressure in a first area, placed upstream the TS-LS overlap area in the feeding direction, and the second pressure plate is arranged to provide a second pressure in a second area, placed downstream the TS-LS overlap area in the feeding direction.