Apparatus to apply vibrations to partially or completely thermofusible articles

Ultrasonic apparatus for operation on material which is at least partially thermofusible, said apparatus comprising ultrasonic generator means including a low frequency generator, an electroacoustic transducer coupled to said generator, a sonotrode coupled to said transducer and constituting a working tool, a counter tool having an upper surface facing said sonotrode, such that the material to be operated on can be transported between the sonotrode and the counter tool, and support means for said transducer, sonotrode and counter tool, said support means comprising an aperiodic support member, said counter tool comprising a base and a projection on said base having an edge of substantially reduced width in relation to said base to constitute a counter bearing impact surface for said working tool permitting simultaneous cutting of the material and fusion of the resulting selvedges at the cut edges, said support member having a recess with a shape corresponding to the base of said counter tool, said base being slidably and demountably mounted in said recess in alignment with said sonotrode, said support member including a lower portion having said recess and an upper portion carrying said sonotrode and to which said transducer is secured.