Apparatus for forming and/or sealing a packaging unit

An apparatus for forming a packaging unit from a pair of parallel horizontal superimposed layers (1) of a heat-sealable material having a given longitudinal axis, comprising:

• (a) vertical anvil means (4) arranged below and extending normal to said material layers, said anvil means being sectional and including:
• (1) a vertical sealing anvil section (4a) having an upper surface (5) that is initially in engagement with the lower surface of the pair of superimposed layers;
• and
• (2) a vertical separating anvil section (4b) arranged adjacent said sealing anvil section and a coplanar therewith in a vertical plane extending parallel with the longitudinal axis of the heat sealable superimposed layers, said separating anvil section being vertically displaceable relative to said sealing anvil section and initially having a refracted first position in which the upper end surface thereof is spaced downwardly from the lower surface of the pair of superimposed layers;
• and
• (b) vertical sonotrode means (3) arranged above and extending normal to the superimposed layers at a location opposite said anvil means, the lower end surface of said sonotrode being normally in engagement with the upper surface of the pair of superimposed layers;
• (c) said sonotrode means being mounted for vertical movement relative to said sealing anvil section, said sonotrode means being operable when said separating anvil section is in said first position to produce a first ultrasonic pulse to effect welding together of the portions of the superimposed layers between said sealing anvil section and said sonotrode;
• (d) said separating anvil (4b) being vertically displaceable relative to said sealing anvil (4a) toward an extended second position in engagement with the bottom surface of the superimposed layers and in which the superimposed layers and the sonotrode means are displaced upwardly away from the upper end surface of said sealing anvil;
• (e) said sonotrode means being operable when said separating anvil is in said second position for producing a second ultrasonic pulse to sever the portion of the superimposed layers opposite said separating anvil section.