Abstract: The invention concerns an ultrasonic device for sealing at least two superimposed sheets, said device comprising a sealing assembly consisting of two elements which are respectively an anvil and a sonotrode, arranged opposite each other so that their facing surfaces form an interstice for passing through the sheets to be sealed, said interstice having an inlet section and an outlet section, the sonotrode vibrating at high frequencies to emit ultrasonic waves, characterised in that means are provided for generating between the superimposed sheets and said sealing assembly a relative movement along a specific feeding direction relative to the sealing assembly, and the section of said passage interstice decreases between its inlet section and its outlet section, and at least one element of said sealing assembly comprises a projecting ridge emerging into said passage interstice and extending along a direction globally parallel to said feeding direction.

Abstract: The invention concerns an ultrasonic device (100) for sealing at least two superimposed sheets (1, 2), said device comprising a sealing assembly consisting of two elements which are respectively an anvil (102) and a sonotrode (101), arranged opposite each other so that their facing surfaces (101′, 102′) form an interstice (103) for passing through the sheets to be sealed, said interstice having an inlet section (104) and an outlet section (105), the sonotrode vibrating at high frequencies to emit ultrasonic waves, characterised in that means are provided for generating between the superimposed sheets and said sealing assembly a relative movement along a specific feeding direction (F) relative to the sealing assembly, and the section of said passage interstice decreases between its inlet section and its outlet section, and at least one element of said sealing assembly comprises a projecting ridge emerging into said passage interstice and extending along a direction globally parallel to said feeding

Abstract: The invention relates to an ultrasonic welding apparatus (100) for welding together at least two superposed sheets (1, 2) made of plastics material and traveling continuously along a predetermined path (F), the apparatus (100) being of the type comprising a sonotrode (101) and an anvil (102) disposed facing each other so that their facing surfaces (101′, 102′) define a through gap (102) through which two superposed sheets (1, 2) to be welded together pass, the gap having an inlet section (104) and an outlet section (105), the sonotrode (101) vibrating at high frequencies to emit ultrasound waves. According to the invention, the anvil is fixed and said facing surfaces of the sonotrode and of the anvil are generally plane and converge towards each other such that the section of said through gap decreases continuously between its inlet section and its outlet section.