Rotary ultrasonic sealer

Horn assembly adapted to be rotatably arranged in a housing (3) of a rotary ultrasonic sealer, and comprising a hollow shaft (1) having a longitudinal axis (2) and a horn (8) arranged coaxially in the hollow shaft (1) and connected to a converter (6) and preferably also a booster (7), the horn (8) being provided with a peripheral sealing area (13) outside an axially free end (12) of the hollow shaft (1) and the housing (3), and wherein the horn (8) is connected to the hollow shaft (1) by means of at least one annular, metallic support (11) extending radially outward from an outer face (14) of the horn (8) and retaining means so as to fixedly retain the horn (8) in the hollow shaft (1), said support (11) being arranged essentially in a point with minimum vibration amplitude in the longitudinal direction of the horn, wherein the at least one annular support (11) is corrugated in cross section such that at least two grooves (17, 18) and one ridge (19) arranged there between are provided between the inner face (10) of the hollow shaft (1) and the outer face (14) of the horn (8), the annular support (11) comprising a first leg (20) and a second leg (21) being interconnected at first ends thereof via a top part (22) and being provided a first bottom part (23) and a second bottom part (24), respectively, at second ends opposite the first ends, characterised in that the support (11) at its periphery comprises a conical surface (26) having a proximal end (61) and a distal end (63), which conical surface (26) is adapted to cooperate with a corresponding conical surface (27) for centring the support (11) with respect to the hollow shaft (1), when the horn (8) is retained in the hollow shaft (1) by means of the retaining means (30).